Objective:To investigate the risk factors for severe postpartum hemorrhage (SPPH) during vaginal delivery of twin pregnancy.Methods:A retrospective analysis was conducted on clinical data from twin pregnancies ≥28 weeks′ gestation undergoing vaginal delivery at Peking University Third Hospital between January 2016 and December 2023. The twin pregnant women were divided into the SPPH group (postpartum hemorrhage ≥1 000 ml within 24 hours) with 22 cases and the non-SPPH group with 171 cases. The differences between the two groups were compared and the risk factors for SPPH were analyzed.Results:(1) The incidence of SPPH during vaginal delivery in twin pregnancies was 11.4% (22/193). The causes of SPPH included 12 cases (54.5%, 12/22) of simple uterine atony, 4 cases (18.2%, 4/22) of uterine atony combined with vaginal lacerations after forceps delivery, and 6 cases (27.3%, 6/22) of uterine atony combined with placental factors. (2) The age and postpartum hospital stay in the SPPH group were significantly higher than those in the non-SPPH group (all P<0.05). Compared to the non-SPPH group, the proportion of hypertensive disorders in pregnancy, accreta placenta implantation, and anemia in the SPPH group were significantly increased, and the birth weight of newborn 1st, the sum of the birth weights of two newborns, the duration of the second stage of labor, and the proportion of labor followed induction were also significantly increased (all P<0.05). (3) Multivariate analysis showed that age ≥38 years ( OR=16.785, 95% CI: 2.679-105.166; P=0.003), the second stage of labor ≥90 minutes ( OR=9.670, 95% CI: 2.532-36.930; P=0.001), hypertensive disorders in pregnancy ( OR=5.945, 95% CI: 1.702-20.761; P=0.005), and anemia ( OR=8.048, 95% CI: 2.086-31.049; P=0.002) were independent risk factors for SPPH in twin pregnancies during vaginal delivery. Conclusions:Anemia should be actively corrected during twin pregnancy. For twin pregnant women with advanced age, hypertensive disorders in pregnancy, or other risk factors of SPPH, if vaginal delivery is chosen, attention should be paid to the management of labor duration, dynamic assessment of the risk of postpartum hemorrhage, and proactive measures should be taken to ensure a smooth vaginal delivery and effectively reduce the incidence of SPPH.

Space radiation is the most important environmental harmful factor in long-term manned spaceflight and deep space exploration, and it may produce deterministic and stochastic effects on tissues and organs. In-depth research into the biological effects, mechanisms, and protective measures of space radiation is essential and serves as an important foundation for exploring radiation biology and promoting major manned space projects. Firstly, this review introduces the spatiotemporal distribution characteristics of space radiation during low-earth orbit flights, manned lunar landings, and deep space exploration missions, as well as the health risks and challenges it posed to astronauts. Then, it discusses medical requirements and exposure limits, risk assessment, and protection technologies included in the space radiation protection system established internationally and over 30 years of Chinese manned spaceflight departments. Finally, it outlines the subsequent work and prospects for further research.

Objective To investigate the effect of triptolide(TPL)on renal interstitial fibrosis in mice with unilateral ureteral obstruction(UUO)and its mechanism.Methods Six male C57BL/6J mice were randomly selected as the sham group,and 12 mice with UUO modeling were randomly divided into the model group(UUO)and the triptolide group(TPL).Changes in serum creatinine(SCr),blood urea nitrogen(BUN),and body weight were compared among the groups.Renal tissue specimens were collected at 14 d after UUO for HE and Masson staining.Immunohistochemistry staining was performed to observe the expression of α-smooth muscle actin(α-SMA)and fibronectin(Fn)in kidney tissues.Western blotting analysis was used to detect the protein expression levels of nucleotide combined with structure of oligomerization domain receptor protein 3(NLRP3),GSDMD,cGSDMD,IL-1β and IL-18.Results At week 1,the body weight of mice in the UUO and TPL groups significantly decreased compared with that in the sham group(P＜0.05).Body weight reduced in the TPL group compared with that in the Sham group at week 2(P＜0.01).There was no significant difference in body weight between the TPL and UUO groups.BUN levels did not differ significantly between the three groups.Compared with the sham group,the SCr level in the UUO group significantly increased[(15.680±1.508)μmol/L](P＜0.01).A reduction in SCr level was observed following TPL administration[(12.550±3.004)μmol/L](P＜0.05).HE staining showed that the renal tubules of mice in the UUO group were significantly dilated and atrophic,with interstitial edema and increased inflammatory cell infiltration,while the pathological damage of renal tissues was significantly alleviated after TPL treatment.Masson staining revealed that interstitial collagen deposition significantly increased in the UUO group(36.350±5.183)％(P＜0.01)and reduced after TPL administration(20.820±3.290)％(P＜0.01).Immunohistochemistry results demonstrated that the IOD levels of α-SMA(1.233±0.045)and Fn(1.337±0.045)were higher in UUO group mice than in the sham group,while the IOD levels of α-SMA(1.047±0.025)and Fn(1.113±0.021)were lower in the TPL group than in the UUO group(P＜0.05).Western blotting analysis indicated that the expression levels of NLRP3,cGSDMD,IL-1β and IL-18 in the UUO group mice were higher than those in the sham group,while the protein expression levels of the above-mentioned indicators significantly decreased after TPL treatment(P＜0.05).Conclusion TPL ameliorates renal interstitial fibrosis in mice with UUO by inhibiting NLRP3-mediated pyroptosis.

Objective:To investigate the risk factors for severe postpartum hemorrhage (SPPH) during vaginal delivery of twin pregnancy.Methods:A retrospective analysis was conducted on clinical data from twin pregnancies ≥28 weeks′ gestation undergoing vaginal delivery at Peking University Third Hospital between January 2016 and December 2023. The twin pregnant women were divided into the SPPH group (postpartum hemorrhage ≥1 000 ml within 24 hours) with 22 cases and the non-SPPH group with 171 cases. The differences between the two groups were compared and the risk factors for SPPH were analyzed.Results:(1) The incidence of SPPH during vaginal delivery in twin pregnancies was 11.4% (22/193). The causes of SPPH included 12 cases (54.5%, 12/22) of simple uterine atony, 4 cases (18.2%, 4/22) of uterine atony combined with vaginal lacerations after forceps delivery, and 6 cases (27.3%, 6/22) of uterine atony combined with placental factors. (2) The age and postpartum hospital stay in the SPPH group were significantly higher than those in the non-SPPH group (all P<0.05). Compared to the non-SPPH group, the proportion of hypertensive disorders in pregnancy, accreta placenta implantation, and anemia in the SPPH group were significantly increased, and the birth weight of newborn 1st, the sum of the birth weights of two newborns, the duration of the second stage of labor, and the proportion of labor followed induction were also significantly increased (all P<0.05). (3) Multivariate analysis showed that age ≥38 years ( OR=16.785, 95% CI: 2.679-105.166; P=0.003), the second stage of labor ≥90 minutes ( OR=9.670, 95% CI: 2.532-36.930; P=0.001), hypertensive disorders in pregnancy ( OR=5.945, 95% CI: 1.702-20.761; P=0.005), and anemia ( OR=8.048, 95% CI: 2.086-31.049; P=0.002) were independent risk factors for SPPH in twin pregnancies during vaginal delivery. Conclusions:Anemia should be actively corrected during twin pregnancy. For twin pregnant women with advanced age, hypertensive disorders in pregnancy, or other risk factors of SPPH, if vaginal delivery is chosen, attention should be paid to the management of labor duration, dynamic assessment of the risk of postpartum hemorrhage, and proactive measures should be taken to ensure a smooth vaginal delivery and effectively reduce the incidence of SPPH.

Space radiation is the most important environmental harmful factor in long-term manned spaceflight and deep space exploration, and it may produce deterministic and stochastic effects on tissues and organs. In-depth research into the biological effects, mechanisms, and protective measures of space radiation is essential and serves as an important foundation for exploring radiation biology and promoting major manned space projects. Firstly, this review introduces the spatiotemporal distribution characteristics of space radiation during low-earth orbit flights, manned lunar landings, and deep space exploration missions, as well as the health risks and challenges it posed to astronauts. Then, it discusses medical requirements and exposure limits, risk assessment, and protection technologies included in the space radiation protection system established internationally and over 30 years of Chinese manned spaceflight departments. Finally, it outlines the subsequent work and prospects for further research.

Objective To investigate the effect of triptolide(TPL)on renal interstitial fibrosis in mice with unilateral ureteral obstruction(UUO)and its mechanism.Methods Six male C57BL/6J mice were randomly selected as the sham group,and 12 mice with UUO modeling were randomly divided into the model group(UUO)and the triptolide group(TPL).Changes in serum creatinine(SCr),blood urea nitrogen(BUN),and body weight were compared among the groups.Renal tissue specimens were collected at 14 d after UUO for HE and Masson staining.Immunohistochemistry staining was performed to observe the expression of α-smooth muscle actin(α-SMA)and fibronectin(Fn)in kidney tissues.Western blotting analysis was used to detect the protein expression levels of nucleotide combined with structure of oligomerization domain receptor protein 3(NLRP3),GSDMD,cGSDMD,IL-1β and IL-18.Results At week 1,the body weight of mice in the UUO and TPL groups significantly decreased compared with that in the sham group(P＜0.05).Body weight reduced in the TPL group compared with that in the Sham group at week 2(P＜0.01).There was no significant difference in body weight between the TPL and UUO groups.BUN levels did not differ significantly between the three groups.Compared with the sham group,the SCr level in the UUO group significantly increased[(15.680±1.508)μmol/L](P＜0.01).A reduction in SCr level was observed following TPL administration[(12.550±3.004)μmol/L](P＜0.05).HE staining showed that the renal tubules of mice in the UUO group were significantly dilated and atrophic,with interstitial edema and increased inflammatory cell infiltration,while the pathological damage of renal tissues was significantly alleviated after TPL treatment.Masson staining revealed that interstitial collagen deposition significantly increased in the UUO group(36.350±5.183)％(P＜0.01)and reduced after TPL administration(20.820±3.290)％(P＜0.01).Immunohistochemistry results demonstrated that the IOD levels of α-SMA(1.233±0.045)and Fn(1.337±0.045)were higher in UUO group mice than in the sham group,while the IOD levels of α-SMA(1.047±0.025)and Fn(1.113±0.021)were lower in the TPL group than in the UUO group(P＜0.05).Western blotting analysis indicated that the expression levels of NLRP3,cGSDMD,IL-1β and IL-18 in the UUO group mice were higher than those in the sham group,while the protein expression levels of the above-mentioned indicators significantly decreased after TPL treatment(P＜0.05).Conclusion TPL ameliorates renal interstitial fibrosis in mice with UUO by inhibiting NLRP3-mediated pyroptosis.

Objective:To compare the pregnancy outcomes of surviving fetuses in monochorionic diam-niotic(MCDA)twin pregnancies after selective feticide or spontaneous single intrauterine fetal demise(sIUFD),and to explore the influencing factors of prognosis.Methods:A total of 219 cases of intra-uterine death of one fetus in MCDA twin pregnancies admitted to Peking University Third Hospital from September 2010 to August 2021 were collected.According to the mode of fetal death,they were divided into the spontaneous sIUFD group(120 cases)and the selective feticide group(99 cases).Data on the maternal conditions during pregnancy,the situation of the intrauterine-dead fetus,and pregnancy out-comes were collected for retrospective case-analysis.Results:The live-birth rates of surviving fetuses in the spontaneous sIUFD group and the selective feticide group were 85.0％and 81.8％respectively,and the total perinatal survival rates of surviving fetuses were 73.3％and 81.8％respectively,and there were no statistically significant differences.Compared with the spontaneous sIUFD group,the selective feticide group had a greater gestational week at delivery,and lower rate of preterm birth before 37 weeks,neonatal asphyxia,and early neonatal mortality.Using the gestational week at delivery as the outcome variable,Cox regression analysis showed that the mode of fetal death was not a risk factor affecting the gestational week at delivery of the surviving fetus,while gestational hypertension and the gestational week of fetal death were independent risk factors affecting the gestational week at delivery of the surviving fetus.Using preterm birth before 37 weeks,intrauterine death of the surviving fetus,and abnormal neonatal cranial ultrasound as outcome variables respectively,unconditional logistic regression analysis showed that the mode of fetal death,the gestational week of fetal death,the position of the dead fetus,and fetal complications were independent risk factors affecting the outcomes of the above-mentioned survi-ving fetuses.According to the results of the univariate analysis,the above risk factors were included in the multivariate regression analysis,and the results were the same as those of the univariate analysis.Conclusion:For MCDA twin pregnancy patients with severe twin-related complications,the prognosis of surviving fetuses after selective feticide is better.The proactive intrauterine intervention and treatment are of great significance for improving the prognosis of surviving fetuses.

Objective:To compare the pregnancy outcomes of surviving fetuses in monochorionic diam-niotic(MCDA)twin pregnancies after selective feticide or spontaneous single intrauterine fetal demise(sIUFD),and to explore the influencing factors of prognosis.Methods:A total of 219 cases of intra-uterine death of one fetus in MCDA twin pregnancies admitted to Peking University Third Hospital from September 2010 to August 2021 were collected.According to the mode of fetal death,they were divided into the spontaneous sIUFD group(120 cases)and the selective feticide group(99 cases).Data on the maternal conditions during pregnancy,the situation of the intrauterine-dead fetus,and pregnancy out-comes were collected for retrospective case-analysis.Results:The live-birth rates of surviving fetuses in the spontaneous sIUFD group and the selective feticide group were 85.0％and 81.8％respectively,and the total perinatal survival rates of surviving fetuses were 73.3％and 81.8％respectively,and there were no statistically significant differences.Compared with the spontaneous sIUFD group,the selective feticide group had a greater gestational week at delivery,and lower rate of preterm birth before 37 weeks,neonatal asphyxia,and early neonatal mortality.Using the gestational week at delivery as the outcome variable,Cox regression analysis showed that the mode of fetal death was not a risk factor affecting the gestational week at delivery of the surviving fetus,while gestational hypertension and the gestational week of fetal death were independent risk factors affecting the gestational week at delivery of the surviving fetus.Using preterm birth before 37 weeks,intrauterine death of the surviving fetus,and abnormal neonatal cranial ultrasound as outcome variables respectively,unconditional logistic regression analysis showed that the mode of fetal death,the gestational week of fetal death,the position of the dead fetus,and fetal complications were independent risk factors affecting the outcomes of the above-mentioned survi-ving fetuses.According to the results of the univariate analysis,the above risk factors were included in the multivariate regression analysis,and the results were the same as those of the univariate analysis.Conclusion:For MCDA twin pregnancy patients with severe twin-related complications,the prognosis of surviving fetuses after selective feticide is better.The proactive intrauterine intervention and treatment are of great significance for improving the prognosis of surviving fetuses.

Objective::To establish the Chinese population's amniotic fluid deepest vertical pocket (DVP) reference curves for dichorionic twin pregnancies and to investigate DVP links with adverse perinatal outcomes.Methods::This retrospective cohort study, conducted at Peking University Third Hospital from August 2011 to December 2020, used data from 375 women aged 20 to 45 years who had dichorionic twin pregnancies that were confirmed through first-trimester ultrasound. After exclusions, reference curves were developed using 318 women with 3,299 DVP scans, and the data analyzed included maternal demographics, pregnancy outcomes, ultrasound measurements, and neonatal information. DVPs were assessed via ultrasound at regular intervals and grouped by gestational age (GA) for analyses. Linear mixed models were used to create amniotic fluid reference curves. Associations between abnormalities and adverse perinatal outcomes were examined using Chi-squared or Fisher's exact tests. Logistic regression provided both crude and adjusted odds ratios, adjusting for pre-pregnancy weight, age, ethnicity, parity, and conception mode. Significance was set at P < 0.05 with 95% confidence intervals (CI), and the analyses were conducted using SPSS ver. 26.0 (IBM Corp., Armonk, NY) and SAS ver. 9.4 (SAS Institute Inc., Cary, NC, USA) software. Results::DVP increased from the first trimester to a maximum at 26 weeks (95% confidence interval ( CI), 2.7-8.3 cm for twin 1 and 2.8-7.9 cm for twin 2) and then decreased gradually toward term. Differences between twins 1 and 2 were significant after 26 weeks (95% CI for twin 1: 5.3, 5.5; 95% CI for twin 2: 4.4, 4.5; P < 0.010). Polyhydramnios of twin 1 increased the risk of large for GA. Oligohydramnios of twin 1 increased the risk of small for GA. Polyhydramnios of twin 2 increased the risk of small for GA, premature birth, and neonatal complications. Oligohydramnios of twin 2 increased the risk of preeclampsia, hypertensive disorder complicating pregnancy, and premature rupture of membranes. Conclusion::Reference curves for twin amniotic fluid volumes vary by GA and differ between twins, with potential implications for pregnancy outcomes.

Objective:To provide clues for in-depth research on radiation protection in deep space exploration missions by reviewing the biological effects of space radiation and biological protection technologies. Literature resource and selection 　Domestic and abroad relevant literatures were searched and reviewed. Literature quotation 　Thirty-nine papers published in China and abroad were cited. Literature synthesis 　Space radiation is the most important environmental harmful factor that affects the health and mission completion of astronauts in deep space exploration missions. It can cause multiple organ cancers throughout the body, degenerative diseases of cardiovascular, central nervous systems, and ocular lens, and acute radiation syndrome of the bone marrow, brain, and gastrointestinal tracts. The effect mechanisms include free radical production, oxidative stress, DNA and other biomolecular breaks, inflammation, cell apoptosis, and bystander effects. Biological protection can be carried out according to the characteristics of the mechanism at different stages of the development of space radiation effects. Conclusions:Deep space radiation can cause health risks such as cancer, degeneration, and acute radiation syndrome, which can be mainly protected and alleviated by reducing free radicals, promoting DNA repair, and inhibiting cell apoptosis.