Objective To explore the impact of different delay time of umbilical cord ligation on the outcome of preterm infants.Methods A total of 266 preterm infants born in the obstetric department of this hospital from January 2021 to December 2022 were selected as the research subjects and divided into the in-stant group(umbilical cord ligation immediately after birth,n=53),30 s group(delayed umbilical cord liga-tion for 30 s,n=50),60 s group(delayed umbilical cord ligation for 60 s,n=55),90 s group(delayed umbili-cal cord ligation for 90 s,n=55)and 120 s group(delayed umbilical cord ligation for 120 s,n=52)according to the random number table method.The Hb and HCT levels and the incidence rates of anemia,blood transfu-sion,hyperbilirubinemia,intracranial hemorrhage,necrotizing enterocolitis(NEC)and bronchopulmonary dys-plasia(BPD)after birth were compared among 5 groups.Results The Hb and HCT levels at 24 h after birth in the 60,90,120 s groups were higher than those in the instant group and 30 s group,moreover the 120 s group was higher than the 60 s group and 90 s group,and the differences were statistically significant(P＜0.05).The anemia incidence rate and blood transfusion rate in the 60,90,120 s groups were lower than those in the instant group and 30 s group,and the differences were statistically significant(P＜0.05).The hyperbil-irubinemia incidence rate in the 120 s group was higher than that in the other 4 groups,and the difference was statistically significant(P＜0.05).The intracranial hemorrhage incidence rate in the 60,90,120 s groups were lower than those in the instant group and 30 s group,and the differences were statistically significant(P＜0.05).The NEC incidence rate in the 60 s and 90 s group was lower than that in the instant group and 30 s group,but the 120 s group was higher than that in the other 4 groups,and the differences were statistically significant(P＜0.05).The BPD incidence rate had no statistical difference among 5 groups(P＞0.05).Con-clusion Delayed umbilical cord ligation for 60 s or 90 s could improve the outcomes of preterm infants.

Objective To establish rabbit model of scoliosis induced with stable asymmetric lumbar loads. Methods Scoliosis was induced in 10 two-month-old New Zealand rabbits using 316L stainless steel springs placed between the unilateral transverse processes of L2 and L5. Serial radiographs were documented before and at 1, 4, 8, 9 and 12 weeks after the operation. At weeks, the rabbits were randomly divided into SR group (n=5) with the spring removed and SK group (n=5) without spring removal. Results All the rabbits survived the experiment with Cobb angle all greater than 10°at the end of the experiment. Significant changes were found in the Cobb angles and kyphotic angles at 1, 4 and 8 weeks after the operation (P<0.05). At 8 weeks, the Cobb angle, the kyphotic angle and the length of the spring were similar between SR and SK groups (P>0.05), and in the 4 weeks following spring removal in SR group, the Cobb angle and the kyphosis decreased significantly compared with those in SK group (P<0.05). Micro-CT showed that the BV/TV of the concave side was greater than that of the convex side. The length of the spring did not show obvious changes during the experiment (P>0.05). Conclusion Asymmetric lumbar loading is a convenient, time-saving, and highly reproducible approach for establishing rabbit models of scoliosis.

Objective To establish rabbit model of scoliosis induced with stable asymmetric lumbar loads. Methods Scoliosis was induced in 10 two-month-old New Zealand rabbits using 316L stainless steel springs placed between the unilateral transverse processes of L2 and L5. Serial radiographs were documented before and at 1, 4, 8, 9 and 12 weeks after the operation. At weeks, the rabbits were randomly divided into SR group (n=5) with the spring removed and SK group (n=5) without spring removal. Results All the rabbits survived the experiment with Cobb angle all greater than 10°at the end of the experiment. Significant changes were found in the Cobb angles and kyphotic angles at 1, 4 and 8 weeks after the operation (P<0.05). At 8 weeks, the Cobb angle, the kyphotic angle and the length of the spring were similar between SR and SK groups (P>0.05), and in the 4 weeks following spring removal in SR group, the Cobb angle and the kyphosis decreased significantly compared with those in SK group (P<0.05). Micro-CT showed that the BV/TV of the concave side was greater than that of the convex side. The length of the spring did not show obvious changes during the experiment (P>0.05). Conclusion Asymmetric lumbar loading is a convenient, time-saving, and highly reproducible approach for establishing rabbit models of scoliosis.