Objective To establish a dose-effect curve of premature condensation chromosome ring (PCC-R)in lymphocytes of human peripheral blood after exposed to high doses of Y-rays. Methods Peripheral blood samples was drawn from three healthy individuals, and exposed to 60Co γ-rays with doses between 0 and 30 Gy. The frequencies of PCC-R in premature condensation chromosome (PCC) cells obtained by Okadaic acid (OA) induction were calculated, and a dose-effect curve was fitted. Results PCC index tapered with dose. Frequencies of PCC-R per cell increased until 20 Gy, and then saturation was observed. The results were fitted to a lineal model up to 20 Gy: y = - 0.020 + 0.052D ,where y was the frequencies of PCC-R per cell, D was the radiation dose (Gy). Conclusins The highest dose could be estimated is 20 Gy by the dose-effect curve established with PCC-R method. Its utility and validity will be verified in the future application of radiation accident.

Objective     To investigate short-term outcomes of robot-assisted Heller-Dor myotomy (RAHM-Dor) for achalasia of cardia and our learning curve experience. Methods     The clinical data and recent follow-up results of 42 patients who received RAHM-Dor from November 2015 to January 2020 in the Department of Thoracic Surgery of the First Affiliated Hospital of Nanchang University were retrospectively analyzed, including 20 males and 22 females with a mean age of 40.8±18.4 years. Results    Dysphagia was the most common symptom, followed by heartburn and regurgitation. The mean operation time was 122.8±23.9 min. The mean blood loss was 47.5±32.7 mL. Two patients suffered mucosal injury, and successfully repaired by suturing during surgery. There was no esophageal fistula, conversion to an open operation or perioperative death in this series. The median length of hospital stay was 8 (6, 9) d. In all patients, the Stooler and Eckardt scores of postoperative 1, 6 and 12 months decreased compared to those of pre-operation (P<0.001). Conclusion     RAHM-Dor is a safe and feasible avenue for the treatment of achalasia of cardia, and can achieve a satisfying short-term results. The learning curve shows a transition to the standard stage from the learning stage after 16-18 operations.