Objective:To study the risk factors for abnormal glucose metabolism in pregnant women with a history of gestational diabetes mellitus (GDM).Methods:A retrospective analysis was performed on pregnant women who had two consecutive deliveries and were was complicated by GDM in the previous pregnancy at the First Affiliated Hospital of Sun Yat-sen University from January 2011 to May 2019. Clinical data of both pregnancies were collected, including general information, fasting blood glucose in early pregnancy and 75 g oral glucose tolerance test (OGTT) results, glycosylated hemoglobin A1c and blood lipid profile at 24-28 gestational weeks. The incidence and risk factors of abnormal glucose metabolism in these cases during the present pregnancy were analyzed. Analysis of variance, Kruskal-Wallis test, SNK- q or LSD- t-test, and Chi-square test were used for data analysis. Single-factor logistic regression analysis was used to analyze the high-risk factors, and multifactor logistic regression analysis was performed to fit the model. Variable collinearity diagnosis was performed using the coldiag2 command. Results:(1) A total of 455 cases were enrolled in the study. According to the fasting glucose level in the first trimester and the OGTT results in the present pregnancy, they were divided into three groups: normal OGTT group ( n=240), GDM group ( n=189), and pre-gestational diabetes mellitus group (PGDM, n=26). The incidence of abnormal glucose metabolism in these patients during the present pregnancy was 47.2% (215/455). (2) Those with a history of GDM had higher pre-pregnancy weight, lower weight gain, higher cesarean section rate, smaller gestational age at delivery, and higher neonatal birth weight in the present pregnancy than those in the previous pregnancy [(55.6±8.5) vs (53.3±7.9) kg, t=-4.059; (11.2±4.2) vs (12.5±4.4) kg, t=4.435; 47.9% (218/455) vs 33.0% (150/455), χ2=20.481; (38.6±1.3) vs (38.8±1.3) weeks, t=2.288; (3 177±463) and (3 114±460) g, t=-2.044; all P<0.05]. (3) In the PGDM group, the 2-h plasma glucose level after 75 g OGTT was higher than that in the previous pregnancy [(11.4±1.1) vs (9.9±1.7) mmol/L, t=-3.299, P=0.002]. (4) In the present pregnancy, the PGDM group had the highest fasting blood glucose in early pregnancy, followed by the GDM group and the normal OGTT group [4.6 mmol/L (4.2-7.6 mmol/L), 4.3 mmol/L (4.0-4.6 mmol/L) and 4.1 mmol/L (3.8-4.4 mmol/L), χ2=34.498, P<0.001]. The PGDM group had the least postpartum weight retention, followed by the normal OGTT group and the GDM group [(1.2±3.9), (1.6±3.9), and (2.6±4.9) kg, F=3.086, P<0.05]. (5) Multivariate logistic regression analysis showed postpartum weight retention and the 1-h and 2-h plasma glucose levels after 75 g OGTT in the previous pregnancy were independent risk factors for abnormal glucose metabolism in pregnant women with a history of GDM (postpartum weight retention: OR=1.054, 95% CI: 1.005-1.106; 1-h plasma glucose: OR=1.284, 95% CI: 1.087-1.516; 2-h plasma glucose: OR=1.272, 95% CI: 1.071-1.511). Conclusions:The incidence of abnormal glucose metabolism is higher in subsequent pregnancy in women with GDM history, which may be related to various factors, such as postpartum weight retention and plasma glucose after 75 g OGTT in the previous pregnancy.

To unvestugate the evolutuon law and unfluenced factors of dussolved organuc matter for electron transfer capacuty durung unutual landfull stage, dussolved organuc matter ( DOM ) was extracted from landfull wastes at dufferent depth. Shewanella oneudensus MR-1 and cutrate uron ( FeCut ) were respectuvely used as electron donor and electron acceptor to measure electron donatung capacuty, electron acceptung capacuty and electron shuttlung capacuty. Afterwards, the unfluenced factors of electron transfer capacuty were studued by analyzung spectral unformatuon. The results showed that proteun-luke components and humuc-luke components were able to transfer electrons, and they also accepted electrons from mucroorganusms. Electron donatung capacuty and electron acceptung capacuty uncreased furstly and then decreased. However, the electron shuttlung capacuty uncreased persustently durung the landfull process. Proteun-luke components were the maun components of dussolved organuc matter durung the unutual landfull stage, and ut was maunly responsuble for the electron donorung capacuty and electron acceptung capacuty of DOM. Electron shuttlung capacuty resulted from humuc-luke components durung the cycluc redox process. Electron shuttlung capacuty persustently uncreased durung the landfull process based on humuc-luke components generated durung the stage.

Reduction capacity ( RC ) is an important index to evaluate the redox ability of dissolved organic matter. In order to determine the RC, hydrophilic organic fractions ( HyI ) isolated from dissolved organic matter extracted from the uncomposted and composted samples were used as electron donators and mediators, and three kinds of irons were chosen as electron acceptors. The results showed that, the RC values from the composted sample were 15. 88, 13. 41 and 51. 45 mmol e -/mol C for the electron acceptors Fe2(SO4)3, Fe(NO3)3 and FeCit, respectively, which were higher than the corresponding values (13. 45, 11. 77 and 43. 16 mmol e-/mol C) from the uncomposted sample. The electron acceptor type shows a dramatic influence on the RC value of HyI. The RC value determined by FeCit was obviously higher than that measured using Fe2( SO4 ) 3 and Fe( NO3 ) 3 , and the microbial reducing capacity of the HyI was lower than the corresponding native reducing capacity. By analyzing the special absorbencies ( SUVA254 and SUVA280 ) , absorbance ratios ( A2/A3 and A4/A6 ) and integrated area from UV-vis spectra, it can be found that the RC was affected by aromatic degree, unsaturated conjugated structure, and molecular weight. Excitation-emission matrix spectra coupled with regional integration analysis showed that the relative content of humic-like substances ( humic-like acids and fulvic-like acids) was the main factor influencing the RC value of HyI. The results obtained can be used to characterize the redox properties of HyI, and reveal its role in the transformation and degradation of pollutants during composting.