Objective To determine the effect of prolonged hyperoxia on neonatal rat lung. Methods Full term and premature newborn SD rats were continuosly exposed to 85% oxygen or room air 7 and 14 days after birth.The activities of 3 different kinds of antioxidant enzyme (AOE) including superoxide dismutase(SOD), glutathion peroxidase (GP) and catalase (CAT) in supernatant fractions of lung homogenates were assessed after 7 and 14 days of exposure. So was the lung hydroproline content. Results (1)AOE acctivitis: Except CAT activity at 14 days of exposure, others AOE activities in O 2 exposed rat pups were significantly higher than those in air exposed controls (P

Objective:To investigate the effects of different concentrations of hydrogen peroxide (H 2O 2) on the expression of histone deacetylase-2(HDAC-2) and mitogen activated protein kinases phosphatases-1(MKP-1) in A549 cells. Methods:The experimental models of A549 cells were established by intervening of different concentrations of H 2O 2(0, 100, 200, 400, 600, 800 μmol/L)for 2 h, 4 h, 8 h, 12 h and 24 h, respectively.The survival rate of A549 cells was detected by thiazolyl blue(MTT) assay, and the apoptosis of A549 cells was tested by lactic dehydrogenase(LDH) assay.The expression of HDAC-2 and MKP-1 protein was detected by Western blot. Results:(1)MTT results showed that compared with the control group (H 2O 2 was 0 μmol/L), the survival rate of A549 cells was decreased with the increase of H 2O 2 concentration at 2 h, 4 h, 8 h, 12 h, 24 h and 48 h. (2)LDH results showed that, compared with the control group, the inhibition rate of A549 cells increased with the increase of H 2O 2 concentration at 2 h, 4 h, 8 h, 12 h, 24 h and 48 h. (3)The expression of HDAC-2 protein decreased ( F=14.588, P<0.01), and the expression of MKP-1 protein increased ( F=64.297, P<0.01) in a concentration-dependent manner with the increase of H 2O 2 concentration at 12 h after H 2O 2 treatment. Conclusions:H 2O 2 participates in oxidative stress injury of lung cells by regulating the expression of HDAC-2 and MKP-1.

Bronchopulmonary dysplasia (BPD) is a common chronic respiratory complication in preterm infants without fully understand the mechanism or effective treatment, which could significantly affect the survival rate and prognosis of these infants. Studies have confirmed that epigenetic mechanisms, including histone modification, non-coding RNA and DNA methylation may play an essential role in the onset and development of BPD. And most related epigenetic changes are reversible, which might serve as a potential target for BPD treatment. Therefore, further studies on epigenetics will shed light on a better understanding of the pathogenesis, prevention, and treatment of BPD.

[Objective] To analyze the influence of the cycle length of hepatitis B surface antigen (HBsAg) double reagent positive samples collected from voluntary blood donors in Guangzhou on the detection results. [Methods] A total of 127 044 blood samples from voluntary blood donors at Guangzhou Blood Center from August 10 to December 9, 2023 were selected. Two ELISA reagents were used for HBsAg detection, and samples with HBsAg double reagent positive and S/CO values<10 were tested continuously for 7 days to observe the changes in their S/CO values. [Results] A total of 505 HBsAg double reagent positive samples were detected, of which 52 had S/CO values less than 10. After 7 consecutive days of uninterrupted testing, the S/CO values of Wantai (median 5 decreased to 3) and Xinchuang (median 5 decreased to 3) showed an overall downward trend, and the HBsAg missed detection rate showed an upward trend (from 0 on the first day to 1/10 000 on the seventh day). A total of 13 cases had negative double reagent test results within the 7-day testing cycle. [Conclusion] With the extension of the detection cycle, the S/CO value of HBsAg detection shows a downward trend, and the missed detection rate of HBsAg shows an upward trend. Samples used for HBsAg detection should be tested promptly after sampling to improve the quality of blood testing.