Based on the competition reaction of target protein, aptamer probe, padlock probe and complementary sequence, a highly sensitive fluorescent aptasensor was developed in this study in combination with rolling circle amplification. In the absence of target protein, the ligation-rolling circle amplification reaction was repressed because the complementary sequence hybridized with aptamer probe to form double-stranded duplex. While in the presence of target protein, the target molecules bound specifically with aptamer probe, inducing displacement of the complementary sequence and hybridization with padlock probe. The padlock probe was circularized with the assistance of E. coli DNA ligase, and the rolling circle amplification process could be accomplished by Phi 29 DNA polymerase. The amplification product contained thousands of repeated sequences which could hybridize with the loop of molecular beacon ( the detection probes) , resulting in a significant fluorescence signal. The effects of length of complementary DNA ( CDNA ) sequence and concentration of padlock probe were investigated. Under the optimized experimental conditions, the model target protein thrombin could be highly sensitively detected by the proposed aptasensing system in a linear range of 0 . 067-32 . 4 nmol/L with a detection limit of 0 . 03 nmol/L ( approximately 90 amol target molecules). Moreover, the presented sensing method was universal for other target analysis by skillfully design of the sequence of aptamer probe and related oligonucleotides.

Objective To evaluate the efficacy difference of different embolization agents in transcatheter embolization for treating massive hemoptysis caused by systemic pulmonary circulation shunt(SPS). Methods The clinical and imaging data in 98 patients with hemoptysis complicating SPS,including bronchodilator in 72 cases,pulmonary tuberculosis in 18 cases and lung carcinoma in 8 cases. All cases were treated with bronchial arterial embolization (BAE). According to different used embolization agents, the cases were divided into the gelfoam group and polyvinyl alcohol(PVA)grains embolization group. All cases were followed up at postoperative 1 d,1,3,6 months as well as 1,2 years. The data were analyzed by using Ridit test. Results Ninety-eight cases of massive hemoptysis were confirmed by DSA,among them,84 cases were complicating pulmonary artery fistula, 18 cases were pulmonary venous fistula and 2 cases were mixed fistula; 32 cases were simple BPS, 62 cases were pulmonary circulation fistula existed in the bronchial arteries and non-bronchial artery and 4 cases were simple non-BPS. The two groups had no complications such as embolism,paraplegia,esophagus-trachea fistula and skin ischemic necrosis. The follow up on postoperative 1 d, at postoperative 1, 3,6 months and at postoperative 1,2 years indicated that among 48 cases in the gelfoam group, 20 cases were cured, 18 cases were significantly effective,6 cases were effective and 4 cases were ineffective,the effective rate was 91.7 % ;among 50 cases in the PVA grain embolization group, 38 cases were cured, 8 cases were significantly effective,4 cases were effective and O case was ineffective, the effective rate was 100%. Moreove no severe complications such as ectopic embolism, paraplegia, esophagus-trachea fistula and skin ischemic necrosis occurred. The difference between the two groups had statistical significance by Ridit analysis. Conclusion Transcatheter embolization for treating massive hemoptysis caused by SPS is safe and reliable,has small trauma, using PVA grains embolization can reduce the long term recurrence rate of hemoptysis.