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 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 investigate the effect of prenatal dexamethasone on short-term outcomes and long-term neurological development in late preterm infants with twin pregnancy.Methods:A total of 315 pregnant women with twin pregnancy and their preterm infants who delivered in Peking University Third Hospital from January 2019 to December 2022 were retrospectively analyzed. The clinical data of pregnant women and preterm infants were collected. They were divided into non-medication group (93 pregnant women and 186 preterm infants), medication after 34 weeks group (123 pregnant women and 246 preterm infants), and medication before 34 weeks group (99 pregnant women and 198 preterm infants). Short-term outcomes of preterm infants were analyzed, including the incidence of neonatal respiratory distress syndrome (NRDS), wet lung, hypoglycemia, neonatal septicemia, intraventricular hemorrhage (IVH), bronchopulmonary dysplasia (BPD) and neonatal necrotizing enterocolitis (NEC). "Ages and Stages Questionnaire-Third Edition (ASQ-3) scale" was used to follow up the late neurological development of preterm infants at the corrected age of 6-54 months, and the level of neurological development was compared.Results:(1) General conditions: the gestational age at delivery in the non-medication group [36.1 weeks (35.6, 36.6 weeks)] was later than that in the medication after 34 weeks group [36.1 weeks (35.2, 36.4 weeks)] and medication before 34 weeks group [35.2 weeks (34.2, 36.2 weeks)] groups, and the differences were statistically significant (all P<0.05). After correcting for gestational age, there was no significant difference in birth weight among the three groups ( H=3.808, P=0.149). There were no significant differences in gender and the proportion of small for gestational age among the three groups (all P>0.05). (2) Short-term outcome: the incidence of wet lung was 7.0% (13/186), 11.0% (27/246) and 16.2% (32/198) in the non-medication group, medication after 34 weeks group and medication before 34 weeks group, respectively, and the difference was statistically significant ( P=0.018). There were no significant differences in the incidence rates of NRDS, hypoglycemia, sepsis, IVH, BPD, and NEC among the three groups (all P>0.05). Logistic regression analysis with gestational age and newborn birth weight as confounding factors showed that early gestational age ( OR=0.884, 95% CI: 0.837-0.933, P<0.001) and increased incidence of selective intrauterine growth restriction type I ( OR=2.967, 95% CI: 1.153-7.639, P=0.024) could both lead to an increased incidence of wet lung. (3) Long-term outcomes: a total of 109 pregnant women completed the follow-up, and 218 preterm infants with a corrected age of 6-54 months at the end of follow-up were enrolled, including 86 cases in the non-medication group, 66 cases in the medication after 34 weeks group, and 66 cases in the medication before 34 weeks group. There were no significant differences in the scores of communication, gross motor, fine motor, problem solving and personal-social among the three groups (all P>0.05). Conclusion:Prenatal administration of a single course of dexamethasone does not affect the neonatal birth weight and short-term outcomes of twin late preterm infants, and has no adverse effect on the neurological development of twin late preterm infants with a corrected age of 6-54 months.

Objective:To explore the produced-radiation brain damage in simulated solar particle events and to provide evidence for health risk assessment of radiation from manned deep space exploration.Methods:According to the main characteristics of solar particle events, mice were treated with total body irradiation (TBI) with 90 MeV protons in a dose range from 0.1 to 2 Gy, with irradiation dose of 0, 0.1, 0.3, 0.5, 1, 2 Gy, respectively. At 3 and 7 d after irradiation, the behavior of mice was examined using balance beam tests, rotarod tests, and new object recognition tests. Then, the density of dendritic spines and the number of Nissl bodies in the hippocampus were measured using Golgi and Nissl staining. The superoxide dismutase (SOD) activity, malondialdehyde (MDA) content, and neurotransmitter content in brain tissue were detected using the WST-8 method, TBA method, and high pressure liquid chromatography (HPLC), respectively. Besides, cell apoptosis was determined using the TUNEL method, and the dose-response relationship, a function of dose change with damage index, was analyzed using linear and linear square fitting method. Finally, the minimum radiation dose causing a significant change in all indicators of brain damage was determined as the brain damage threshold.Results:Compared to the control group, 1 Gy proton irradiation result ed in a significant decrease in the density of filopod dendritic spines ( t = 1.82, 2.30, P < 0.05) and a significant increase in abnormal Nissl bodies in the CA1 region ( t = 2.44, 3.77, P < 0.05). At 3 and 7 d after irradiation, as well as a significant increase in the DA ( t = 2.52, P<0.05) and Glu contents ( t = 4.04, P < 0.05) on day 7. In contrast, 2 Gy proton irradiation result ed in a decrease in SOD activity on day 3 ( t = 3.44, P < 0.05), and an increase in the MDA content ( t = 1.90, 2.14, P < 0.05), hippocampal cell apoptosis (t = 3.91, 3.54, P < 0.05), and 5-HT levels ( t = 2.81, 2.69, P < 0.05), together with a decrease in climbing time in the rotarod tests ( t = 2.85, 2.64, P<0.05) and propensity to recognize new objects ( t = 2.87, 2.84, P < 0.05) on days 3 and 7. Furthermore, a dose-response relationship was observed in the dose range from 0.1 to 2 Gy ( R2=0.74-0.99). Conclusions:The dose threshold of 90 MeV protons inducing brain damage in mice is inferred to be 1 Gy, and 14 dose-response models are developed, providing a biological basis for organ dose capping and risk assessment of crew experiencing short-term deep space flights.