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Chimeric RNA is a fusion transcript comprising of exon fragments from different genes. There are three splicing types: chromosome rearrangements, trans-splicing, cis-splicing, and the recently mentioned circular chimeric RNA. The traditional methods for the detection of chimeric RNA includes chromosome karyotype analysis, FISH, DNA microarray, etc., but their specificity, sensitivity and accuracy for the detection of chimeric RNA are poorly understood. With the development of sequencing technology, second-generation sequencing technology has shown strong data processing capabilities and can detect chimeric RNA through high-throughput sequence analysis. Currently, detection methods making use of high-throughput sequencing datasets includes FusionCatcher, SOAPfuse, EricScript, etc. For validation of the detected chimeric RNA, the commonly used methods include PCR, RPA, agarose gel electrophoresis, sanger sequencing, etc. The development of newly introduced techniques has led to the discovery of different novel chimeric RNA, the third and fourth generation sequencing has also been developed and nearly mature, and the sequencing technology taking PacBio as an example has also brought a new dawn to the discovery of chimeric RNA, but each of them has its advantages and disadvantages, mainly focusing on its cost, false positive rate, detection time, etc. This paper basically describes various different techniques that can be utilized for the detection and validation of chimeric RNA.
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Chimeric RNA is a fusion transcript composed of exons from two or more different genes and generated by chromosome rearrangement or RNA splicing. Chimeric RNAs have the potential to encode novel proteins or function as non-coding RNAs. Chimeric RNAs were ubiquitously expressed across different cancers and normal tissues. To date, mechanistic and functional studies of chimeric RNAs still remain unclear. Precise definition and terminology in the research field of chimeric RNA will be discussed in this review. The formation, classification and clinical significance of chimeric RNAs in cancer progression will be summarized. Previous studies showed that products of chimeric RNAs may play important roles in regulating cell proliferation, motility, invasion and apoptosis through encoded fusion proteins or long non-coding chimeric RNAs. In cancer, chimeric RNA and its encoded specific protein or non-coding RNA can regulate tumorigenesis by changing cell phenotypes or directly affecting gene expression or regulatory pathways, which have the potential to be important diagnostic biomarkers and therapeutic targets. In recent years, more and more cancer-specific chimeric RNAs have been discovered from multiple types of cancers and used as therapeutic targets due to their vital roles in disease prognosis. Therefore, this review will focus on the functions and applications of chimeric RNAs in different tumors, which can shed a light on cancer diagnosis and therapeutics from the new perspective.
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Traditionally, chimeric RNA is thought to be generated by chromosome rearrangement, and its products (RNAs and proteins) were once considered as unique features of cancer. However, with the advancement of next-generation sequencing technologies and the development of bioinformatics software tools, increasing numbers of chimeric RNAs are being identified from various RNA-Seq database. Recently, numerous chimeric RNAs were discovered in human normal tissues and cell lines, with physiological functions. Besides chromosome rearrangement, chimeric RNAs are formed by different molecular mechanisms, including trans-splicing, cis-splicing of adjacent genes. Chimeric RNAs, without chromosomal changes, are regulated at the transcriptional level, and they show specific physiological functions and regulation patterns. Their dysregulation may induce cell differentiation and tumorogenisis. In addition, chimeric RNAs also play roles in normal cell growth and/or migration, cell cycle and apoptosis, induce genomic aberration by influencing chromosome rearrangement, act as potential competitive endogenous RNA, and influence stem cell differentiation. The expression of chimeric RNAs in specific tissues and cell development stages has the potential to be used as diagnostic and therapeutic biomarkers. Histological mapping studies can improve the specificity of treatment for unique cell types, and the chimeric RNA provides a new perspective to achieve this goal. The widespread existence of chimeric RNAs suggests that they may extend the diversity of genomes in human and higher animals.
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<p><b>BACKGROUND</b>The emergency department (ED) has a pivotal influence on the management of acute heart failure (AHF), but data concerning current ED management are scarce. This Beijing AHF Registry Study investigated the characteristics, ED management, and short- and long-term clinical outcomes of AHF.</p><p><b>METHODS</b>This prospective, multicenter, observational study consecutively enrolled 3335 AHF patients who visited 14 EDs in Beijing from January 1, 2011, to September 23, 2012. Baseline data on characteristics and management were collected in the EDs. Follow-up data on death and readmissions were collected until November 31, 2013, with a response rate of 92.80%. The data were reported as median (interquartile range) for the continuous variables, or as number (percentage) for the categorical variables.</p><p><b>RESULTS</b>The median age of the enrolled patients was 71 (58-79) years, and 46.84% were women. In patients with AHF, coronary heart disease (43.27%) was the most common etiology, and myocardium ischemia (30.22%) was the main precipitant. Most of the patients in the ED received intravenous treatments, including diuretics (79.28%) and vasodilators (74.90%). Fewer patients in the ED received neurohormonal antagonists, and 25.94%, 31.12%, and 33.73% of patients received angiotensin converting enzyme inhibitors/angiotensin receptor blockers, beta-blockers, and spironolactone, respectively. The proportions of patients who were admitted, discharged, left against medical advice, and died were 55.53%, 33.58%, 7.08%, and 3.81%, respectively. All-cause mortalities at 30 days and 1 year were 15.30% and 32.27%, respectively.</p><p><b>CONCLUSIONS</b>Substantial details on characteristics and ED management of AHF were investigated. The clinical outcomes of AHF patients were dismal. Thus, further investigations of ED-based therapeutic approaches for AHF are needed.</p>
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<p><b>OBJECTIVE</b>To study the effects of comprehensive interventions in community on smoking, chronic bronchitis, and asthma in rural areas of Beijing.</p><p><b>METHODS</b>Twenty-three villages in rural areas of Beijing were randomly divided into interventional (13 villages) and control villages (10 villages) in 1992. Comprehensive interventions including education of former-smokers and improvement of living environment were carried out in the interventional villages, and none was done in the control villages. In April 2000, surveys on smoking, chronic bronchitis, and asthma were carried out among 34,436 participants aged 15 or more in the interventional and control villages. During the same period, knowledge on prevention from chronic obstructive pulmonary diseases (COPD), living environments, and smoking were assessed among 1658 high-risk individuals of COPD at baseline and following-up period.</p><p><b>RESULTS</b>The scores of knowledge and improvement on living environments in the interventional villages were significantly higher than those in control villages (P < 0.001). The decrease rate of smoking and current smoking rate in the interventional villages were significantly higher than in the control villages (0.4% vs -0.8%, P < 0.001; 2.4% vs 1.3%, P < 0.001) in men, while not different in women (P > 0.05). Among never smokers at baseline, the accumulated incidence of smoking among people aged 15 to 24 from 1993 to 2000 was significantly lower in the interventional villages than in the control villages in men (18.9% vs 23.7%, P = 0.005) and in women (0% vs 0.7%, P = 0.005). Daily cigarettes smoked by smokers in the interventional villages were less than in control villages in both men (14.8 +/- 7.0 vs 17.2 +/- 8.2 cigs daily, P < 0.001) and women (12.8 +/- 6.9 vs 13.4 +/- 7.2 cigs daily, P = 0.088). The increase of prevalence of chronic bronchitis in the interventional villages was less than in the control villages (men: 0.9% vs 1.3%, P = 0.012; women: 0.1% vs 0.3%, P = 0.003). After the age factor is adjusted, odds ratio (OR) for accumulated incidence of chronic bronchitis from 1993 to 2000 in the interventional villages were 0.80 (95%CI: 0.60-1.07) for men, 0.76 (95%CI: 0.45-1.28) in women. The OR for asthma was not significant in both men and women.</p><p><b>CONCLUSIONS</b>Comprehensive interventions in community may improve knowledge of COPD prevention and living environments, decrease the smoking rate, cigarettes smoked per day, and incidence of chronic bronchitis, but have no significant effects on asthma.</p>