Subject recruitment is an important part of clinical researches. It should follow the ethical principles of fairness and representativeness. The recruitment process should pay attention to protecting the privacy of sub-jects. Various recruitment materials must be approved by the ethics committee before use. Whether could recruit el-igible subjects during Phase I clinical trials will have a significant impact on the results, which should attract the relevant persons′attention including the ethics committee, researchers, clinical research associate and the sponsor.

Objective To detect the content of plasma ctDNA and the mutation rate of BRAF V600E in plasma of patients with thyroid carcinoma ,and to explore its clinical significance. Methods Plasma ctDNA was extracted from 16 patients with thyroid carcinoma and 59 patients with benign thyroid nodules by using the blood genomic DNA Extraction Kit. The ctDNA content was detected by fluorescence quantitative PCR ,and the mutation of circulating BRAF V600E was detected by PCR and sequencing. Then the clinical significance was analyzed by combined detection analysis. Results The content of ctDNA in thyroid cancer group was significantly higher than that in benign nodule group (P < 0.01). BRAF V600E mutation detection showed that the mutation rate was 43.75%,but benign nodules had no mutation. Parallel combined detection improved the sensitivity and the specific-ity of the combined detection was higher. Conclusion Combined detection of ctDNA and BRAF V600E in plasma is helpful for differential diagnosis of benign and malignant thyroid nodules.

Objective To investigate the methods of screening specific aptamers for (EpCAM)Gpositive prostate cancer (PCa)cells by cellGSELEX technique.Methods A random DNA library was designed to screen EpCAMGspecific DNA aptamers from human prostate cancer cells expressing EpCAM molecule by cellGSELEX technique.After 12 rounds of in vitro screening,DNA products were cloned and sequenced.Flow cytometry and cellular immunofluorescence were used to detect the specific binding ability of aptamers to target cells.Results Two aptamers of Ep1 and Ep2 were selected.Both of them could specifically bind to EpCAMGpositive cancer cells LNCap,PCG3 ,DU1 45 , and HEK293T cells transfected with target molecule.The binding rates of Ep1 were 61.0%,74.3%,5 9.1% and 60.3%.The binding rates of Ep2 were 65.1%,77.8%,54.2% and 58.3%.Neither of them could bind to HEK293T cells transfected with empty vector with the binding rate of 5.4% in Ep1 and 3.3% in Ep2,respectively.Flow cytometry analysis and confocal images indicated that the EpCAM aptamers could specifically recognize human PCa cells expressing EpCAM,but could not bind to EpCAMGnegative cells.Conclusion EpCAM aptamers derived from cellGSELEX technology can recognize and bind to EpCAMGpositive PCa cells specifically,which may provide new ideas for the specific diagnosis and targeted therapy of prostate cancer,and lay an experimental basis for the other specific diagnosis and treatment schemes of malignant tumors.

Objective:To analyze the viral nucleic acid and cytokines in 12 children with 2019-nCoV infection.Methods:Clinical and laboratory data of the children diagnosed with 2019-nCoV infection in Guangzhou Women and Children′s Medical Center from January to April 2020 were retrospectively analyzed. Throat and anal swabs were collected on alternate days for the detection of 2019-nCoV nucleic acid by fluorescence quantitative PCR. Flow cytometry was used to detect serum cytokines including IFN-γ, IL-1β, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, IL-12p70, IL-17A, IL-17F, IL-22, TNF-α and TNF-β during the early (both throat and anal swab tests were positive), the intermediate (throat swab test was negative, while anal swab test remained positive), and the convalescence (both throat and anal swab tests were negative) stages of infection.Results:A total of 12 children were enrolled in this study. The male-to-female ratio was 5∶1. The average age was (7.0±4.3) years. There were two asymptomatic, five mild and five common cases. No severe or critical cases were involved. Initially, throat and anal swab nucleic acid tests were simultaneously positive in nine children newly diagnosed in our hospital and the median time of viral shedding in throat swab was longer than that in throat swab [32 (4.5, 45.0) d vs 3 (2, 9) d, Z=11.0, P=0.010]. The median difference of viral shedding time between anal swab and pharyngeal swab was 25.5 (1.5, 42.8) d. The overall levels of serum cytokines IL-17A, IL -4 and IL-5 in different stages of the disease (early, intermediate and convalescence stage) were statistically different ( Z or F, P values were 8.33, 0.016; 5.36, 0.010 and 6.56, 0.004, respectively), and a significant increase was observed in the intermediate stage of infection. IL-17F, IL-2 and IL-22 were all increased during the infection, but there was no significant statistical difference among the three stages ( P>0.05). Conclusions:It was noted that intestinal viral shedding needed a longer time. Although the infectivity has not been determined, higher requirements have been put forward for disease prevention and control. Cytokines secreted by Th2 and Th17 cells were involved in the immune response in children with non-severe 2019-nCoV infection. Monitoring viral shedding and cytokine changes in pediatric patients would be conducive to disease assessment.