Circular RNAs (circRNAs) are a new class of noncoding singlestranded RNAs that differ from linear microRNAs (miRNAs), since they form covalently closed loop structures without free 3 0 poly(A) tails or 5 0 caps. circRNAs are the competitive endogenous RNAs (ceRNAs) by binding to miRNA through miRNA response elements (MREs) (i.e., "miRNA sponge"), thereby reducing the quantity of miRNA available to target mRNA, subsequently promoting mRNA stability or protein expression, which involves the initiation and progress of human diseases. Owing to these features of abundance, stability, conservative property, and tissue and stage specificity, widely distributing in the extracellular space and in various bodily fluids, circRNAs can be considered as potential biomarkers for various diseases. Here, we reviewed the promising circRNAs being disease biomarkers, focused on their regulatory function by acting as miRNA sponges, and described their roles in cancer, cardiovascular or neurodegenerative diseases, osteoarthritis, rheumatoid arthritis, diabetes, and other human aging-related diseases, which provide a new direction for pathogenesis, diagnosis, and treatment of human aging-related diseases.Circular RNAs (circRNAs) are a new class of noncoding singlestranded RNA, 1 characterized by covalently closed loop structures without free 3 0 poly(A) tails or 5 0 caps. These features differentiate them from linear RNAs, 2 long noncoding RNAs (lncRNAs), and mi-croRNAs (miRNAs). 3 Although circRNAs were first discovered in the 1990s in viruses, viroids, and tetrahymena, 4 little attention has been paid to their function. 4,5 At that time, they were considered abnormal products, resulting from splicing errors. 3,6 In addition, circRNAs are often found in low abundance, and the traditional methods used to study linear RNAs are not applicable. With recent developments in biochemical-enrichment methods, especially high-throughput RNA sequencing and circRNAs microarray, more than 30,000 circRNAs have been discovered. 7 They are widely expressed in yeasts, plants, protists, fruit flies, worms, zebrafish, mice, rats, and humans. 8 Compared with the levels of their linear isomers, circRNA expression levels can be increased by 10-fold or more, 9 an indication of their potential abundance. Owing to their distinctive structure, they can resist exonuclease activity and are extremely stable. 1 The average lifetime of a 3 0 / 5 0 -linked circRNA is 2$5 times longer than that of a linear mRNA. 1 In addition, the expression levels of circRNAs are tissue and stage specific, and a number of highly abundant circRNAs have been found to exist in human peripheral blood (PB), 10 indicating that circRNAs can act as biomarkers to screen, diagnose, characterize, and monitor various diseases. circRNAs have many biological functions, including regulating host gene splicing and transcription, 11 acting as miRNA 12 and protein sponges, 8 reacting with proteins, 13 and serving as protein-coding circRNAs. 14 Many studies [15][16][17] have indicated that circRNAs con...

Intravenous acetaminophen reduced pain after cardiac surgery, but not opioid consumption. Intravenous acetaminophen can be an effective analgesic adjunct in patients recovering from median sternotomy.

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