Biclustering of transcriptome sequencing data reveals human tissue-specific circular RNAs.

BACKGROUND: Emerging evidence has been experimentally confirmed the tissue-specific expression of circRNAs (circRNAs). Global identification of human tissue-specific circRNAs is crucial for the functionality study, which facilitates the discovery of circRNAs for potential diagnostic biomarkers. RESULTS: In this study, circRNA back-splicing junctions were identified from 465 publicly available transcriptome sequencing samples. The number of reads aligned to these identified junctions was normalized with the read length and sequence depth for each sample. We generated 66 models representing enriched circRNAs among human tissue transcriptome through biclustering algorithm. The result provides thousands of newly identified human tissue-specific circRNAs. CONCLUSIONS: This result suggests that expression of circRNAs is not prompted by random splicing error but serving molecular functional roles. We also identified circRNAs enriched within circulating system, which, along with identified tissue-specific circRNAs, can serve as potential diagnostic biomarkers.

Central nervous system infection in patients with postirradiated nasopharyngeal carcinoma: a case-controlled study.

BACKGROUND: It has been assumed that postirradiated nasopharyngeal carcinoma (NPC) patients are prone to central nervous system (CNS) infection. OBJECTIVE: The purpose of this study was to better understand this clinical entity. METHODS: From September 1989 to May 2006, we conducted a retrospective study of 18 postirradiated NPC patients with CNS infection including brain abscess, cavernous sinus thrombosis, epidural abscess, and meningitis in our institute. During the same period, 18 NPC patients without CNS infection who were matched for tumor stage, age, and gender with the study group were randomly selected from the cancer registry at our hospital and enrolled as the control group. All medical records of these patients were evaluated. RESULTS: The local tumor relapse rate, nasopharyngeal radiotherapy dose, and skull base osteoradionecrosis were all significantly higher in patients with CNS infection (p = 0.003, 0.011, and 0.001, respectively). Although the incidences of otitis media and chronic rhinosinusitis were higher in patients with CNS infection, there were no significant differences between the two groups (p = 0.469 and 0.568, respectively). The in-hospital mortality was 61.1%, and the overall mortality of CNS infection was 83.3%. There was a significant difference in overall survival rate between the two groups (p = 0.001). CONCLUSIONS: Postirradiated NPC patients with skull base osteoradionecrosis are prone to have CNS infection. CNS infection is an adverse prognostic factor in postirradiated NPC patients.