Objective　 To investigate the profile of telomerase and telomerase RNA expression in nasopharyngeal carcinogenesis (NPC) induced by N,N'dinitrosopi perazine (DNP) and examined histolofically. Methods Nasopharyngeal carcinomas o f rats were induced by DNP and examined histologically. PCR-ELISA and nested R T -PCR were used to assay telomerase and telomerase RNA expression at different s tages in the nasopharyngeal tissues of rats. Results　 During the carcinogenesis p rocess, telomerase activity increased along with the formation of a nasopharynge al carcinoma. Telomerase expression was positively related with nasopharyngeal c arcinogenesis. Telomerase RNA expression was present and did not change during t he NPC process. Expression of telomease RNA was earlier than telomerase activat ion. Telomerase activation and telomerase RNA expressin were also detected in th e pre-cancerous nasopharyngeal lesions. Conclusion　 Telomerase activation may p articipate in the onset and progression of NPC, and is an early step in NPC.

Purpose To explore the subcortical structure characteristics in autism spectrum disorder(ASD)aged 12-18 years old and the developmental characteristics of abnormal regions with age.Materials and Methods A total of 102 adolescents aged 12-18 years old meeting the diagnostic criteria for ASD in diagnostic and statistical manual,fifth edition and 42 gender and age matched typically developing controls were enrolled from March 2013 to January 2021 in Peking University Sixth Hospital.Structural magnetic resonance imaging scans were performed on all participants.The freeSurfer software was used to process the 3D T1 images of all participants and segment the subcortical regions.Covariance analysis was performed to compare the volumes of subcortical regions between the two groups.Analysis of variance and covariance were used to explore the developmental differences of brain regions with significant group differences within the ASD and control groups in the age groups of 12-13,14-15 and 16-18,as well as between the ASD and control groups in these age groups.Results Compared to the control group,the volumes of the right caudate,right pallidum,left hippocampus,and corpus callosum anterior region were significantly increased in the ASD group(F=4.522,5.955,7.191,5.326,P<0.05).The volume of the corpus callosum anterior region showed significant differences among the aged 12-13,14-15 and 16-18 years groups of the control group(F=5.248,P=0.01),while there was no significant difference among these three groups of the ASD group(F=2.345,P=0.101).Conclusion Adolescents with ASD aged 12-18 years show abnormalities in multiple subcortical structures,and the developmental characteristics of the corpus callosum anterior region are different from typically developing controls,suggesting that the brains of adolescents with ASD have distinct developmental features.