Background and purpose:As a new and important radiotherapy technique,intensity-modulated radiation therapy(IMRT) has been widely used in the clinic,but it requires longer time to deliver for one treatment session.The purpose of this study was to investigate the radiobiological effects of CNE and A549 cell lines irradiated by IMRT model.Methods:Part Ⅰ:The radiobiological characteristics of CNE and A549 cell lines were studied with standard clonogenic assays,using standard liner-quadratic model and incomplete repair model to fit the dose-survival curves.Part Ⅱ:a total dose of 8 Gy was given in two fractions with different interfraction intervals to compare the differences of cell surviving fractions(SF).Part Ⅲ:fractionated irradiation of 2 Gy,2 Gy?2,2 Gy?3,2 Gy?4 were given with one fraction per day simulating clinical dose-time-fractionation pattern in 2,20 and 40 min per fraction,respectively.Results:The ?/? of CNE and A549 was 1.76 and 12.41 Gy,respectively;the cell surviving fractions increased when the interfraction interval was longer,The values of SF2 were 0.0237 and 0.0243 in 2 min irradiation group,0.0304 and 0.0296 in 20 min irradiation group,and increased to 0.0378 and 0.0359 in 40 min irradiation group,respectively.Conclusion:The prolonged fraction delivery time would significantly decrease theradiobiological effects,it is strongly recommended that the delivery time be kept as short as possible,or do appropriate dose compensation.

We present a case report of a healthy neonate born by vaginal delivery to a woman who had recovered from COVID-19 after 37 days of discharge. The pregnant woman had fever, cough, and chills at 33 +1 gestational weeks and was diagnosed with COVID-19 by coronavirus nucleic acid test one day later. She recovered and was discharged after a series of treatment, and the 2019 novel coronavirus nucleic acid test and pulmonary CT were negative at the 2nd and 4th weeks after being discharged. The patient was admitted in early labor at 38 +4 gestational weeks and delivered a healthy newborn vaginally at that day. Both the mother and the baby were in good condition. All the maternal or neonatal specimens taken immediately after birth in the delivery room for 2019 novel coronavirus nucleic acid tests were negative, including the maternal pharynx, rectal and cervical secretions, amniotic fluid, an neonatal pharynx and rectal swabs. The qualitative examination of 2019 novel coronavirus antibodies in the maternal venous blood test showed that both IgG and IgM were positive. While the same test for neonatal cord blood and femoral vein blood showed negative results. No inflammatory reaction was found in the placenta and immunohistochemistry detection of novel coronavirus N protein was negative. The mother and newborn were observed postnatally and treated in the same ward, neither of them had fever, cough or fatigue, and were discharged three days after delivery. The qualitative examination of 2019 novel coronavirus antibodies (IgM and IgG) in the femoral vein blood of the nenonate 27 days old showed negative results.

Objective    To investigate the early clinical results of MitraClip system in domestic patients. Methods     We retrospectively analyzed the clinical data of 36 patients who underwent transcatheter edge-to-edge repair procedure using MitraClip system in Beijing Fuwai Hospital, Shenzhen Fuwai Hospital and Fuwai Yunnan Cardiovascular Hospital between January and June 2021. There were 24 males and 12 females, with a median age of 70 (47-86) years. Ten (27.8%) patients had 3+ mitral regurgitation (MR) and 26 (72.2%) patients had 4+ MR preoperatively. Results    All procedures were successfully performed. The reduction in MR was 2+ at least immediately after surgery, and 91.7% of patients had MR≤2+ at 3 days postoperatively. There was no statistical difference in left ventricular ejection fraction change postoperatively. Forward velocity and peak gradient of mitral valve were increased after the procedure. Mean gradient of mitral valve were increased at 3 days postoperatively than immediately after surgery (P<0.001). Two patients had acute pericardial effusion intraoperatively, and received pericardial puncture and drainage immediately. Conclusion    MitraClip system has been applied well in domestic patients and can significantly improve MR. This sutdy has a good consistency with foreign studies, and the early results are satisfactory.