Folic Acid Supplementation and the Association between Maternal Airborne Particulate Matter Exposure and Preterm Delivery: A National Birth Cohort Study in China.

BACKGROUND: Potential modification of the association between maternal particulate matter (PM) exposure and preterm delivery (PTD) by folic acid (FA) supplementation has not been studied. OBJECTIVE: We examined whether FA supplementation could reduce the risk of PTD associated with maternal exposure to PM in ambient air during pregnancy. METHOD: In a cohort study covering 30 of the 31 provinces of mainland China in 2014, 1,229,556 primiparas of Han ethnicity were followed until labor. We collected information on their FA supplementation and pregnancy outcomes and estimated each participant's exposure to PM with diameters of ≤10µm (PM10), 2.5µm (PM2.5), and 1µm (PM1) using satellite remote-sensing based models. Cox proportional hazard regression models were used to examine interactions between FA supplementation and PM exposures, after controlling for individual characteristics. RESULTS: Participants who initiated FA ≥3 months prior to pregnancy (38.1%) had a 23% [hazard ratio (HR)=0.77 (95% CI: 0.76, 0.78)] lower risk of PTD than women who did not use preconception FA. Participants with PM concentrations in the highest quartile had a higher risk of PTD [HR=1.29 (95% CI: 1.26, 1.32) for PM1, 1.52 (95% CI: 1.46, 1.58) for PM2.5, and 1.22 (95% CI: 1.17, 1.27) for PM10] than those with exposures in the lowest PM quartiles. Estimated associations with a 10-µg/m3 increase in PM1 and PM2.5 were significantly lower among women who initiated FA ≥3 months prior to pregnancy [HR=1.09 (95% CI: 1.08, 1.10) for both exposures] than among women who did not use preconception FA [HR=1.12 (95% CI: 1.11, 1.13) for both exposures; pinteraction<0.001]. The corresponding association was also significantly lower for a 10-µg/m3 increase in PM10 [HR=1.03 (95% CI: 1.02, 1.03) for FA ≥3 months before pregnancy vs. 1.04 (95% CI: 1.03, 1.04) for no preconception FA; pinteraction<0.001]. CONCLUSION: Our findings require confirmation in other populations, but they suggest that initiating FA supplementation ≥3 months prior to pregnancy may lessen the risk of PTD associated with PM exposure during pregnancy among primiparas of Han ethnicity. https://doi.org/10.1289/EHP6386.

Tissue microarrays in pathological examination of apoptotic acinar cells induced by dexamethasone in the pancreas of rats with severe acute pancreatitis.

BACKGROUND: The good therapeutic effects of large dose of dexamethasone on severe acute pancreatitis (SAP) patients have been proved. This study was designed to investigate the influence of dexamethasone on apoptosis of acinar cells in the pancreas of rats with SAP and the protein expression of the apoptosis-regulating genes Bax and Bcl-2. METHODS: Ninety Sprague-Dawley rats with SAP were randomly divided into a model group and a dexamethasone treated group (45 rats in each group), and another 45 rats formed the sham operation group. Survival rates were calculated and gross pathological changes in the pancreas of each group were observed under a light microscope 3, 6 and 12 hours after operation. Tissue microarray technology was applied to prepare pancreatic tissue sections. The changes in Bax and Bcl-2 protein expression levels of pancreatic tissues from each group were assessed by immunohistochemical staining, and TUNEL staining was used to evaluate changes in apoptosis index. RESULTS: The model and treated groups did not differ in mortality at each time point. The pathological score for the pancreas in the treated group was significantly lower than that in the model group at 3 and 6 hours. The positive rates of Bax protein expression in the head and tail of the pancreas in the treated group at all time points were all markedly higher than those of the model group. The positive rate of Bcl-2 protein expression in the head of the pancreas in the treated group was significantly higher than that of the model group at 3 hours. TUNEL staining showed that the pancreas head and tail apoptosis indices of the treated group were markedly higher than those of the model group after 6 hours. CONCLUSIONS: Apoptosis may be a protective response to pancreatic cell injury. The mechanism of action of dexamethasone in treating SAP may be related to the apoptosis of acinar cells in the pancreas induced by apoptosis-regulating genes such as Bax and Bcl-2. The advantages of tissue microarrays in pathological examination of the pancreas include saving of time and energy, efficiency and highly representative.

Study of the protective effects of dexamethasone on multiple organ injury in rats with severe acute pancreatitis.

CONTEXT: Pancreas, lung, kidney and liver injury has been proven to play an important role in severe acute pancreatitis. OBJECTIVE: To observe the protective effects of dexamethasone on multiple organs (pancreas, lung, kidney and liver) in rats with severe acute pancreatitis. ANIMALS: One hundred and thirty-five Sprague-Dawley rats. DESIGN: Ninety rats were prepared as severe acute pancreatitis models and were randomly divided into a control group and the dexamethasone treatment group (45 rats in each group). Another 45 rats were selected to be the sham operation group. Each group was randomly subdivided into 3 subgroups which were observed at 3, 6, and 12 h after surgery (15 rats in each subgroup). MAIN OUTCOME MEASURES: The survival, gross and pathological findings under the light microscope, and the pathological scores of multiple organs in each group were recorded. RESULTS: There was no significant difference in survival between the dexamethasone treatment group and the control group (P=0.494). The pancreas pathological score was significantly lower in the dexamethasone treatment group than in the control group at the various time intervals (overall: P<0.001; 3 h: P=0.019; 6 h: P=0.010, 12 h: P<0.001). The lung pathological score was significantly lower in the dexamethasone treatment group than in the control group at 6 and 12 h (P=0.023 and P<0.001, respectively). The kidney (P<0.001) and liver (P=0.009) pathological scores were also significantly lower in the overall dexamethasone treatment group than in the overall control group, but significant differences were found only in some time intervals (kidney: 6 and 12 h, P=0.006 and P=0.044, respectively; liver: 12 h, P=0.046). CONCLUSION: Intravenous injection of dexamethasone can alleviate pancreas, lung, kidney and liver injury of rats with severe acute pancreatitis and may have protective effects on multiple organ injury.