Publications by authors named "Hang An"

11 Publications

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Associations between endocrine-disrupting heavy metals in maternal hair and gestational diabetes mellitus: A nested case-control study in China.

Environ Int 2021 Jul 24;157:106770. Epub 2021 Jul 24.

Institute of Reproductive and Child Health, Peking University/ Key Laboratory of Reproductive Health, National Health Commission of the People's Republic of China, Beijing 100191, PR China; Department of Epidemiology and Biostatistics, School of Public Health, Peking University, Beijing 100191, PR China.

Background: Exposure to environmental endocrine disruptors (EDCs) may lead to abnormal glucose metabolism and, potentially, gestational diabetes mellitus (GDM).

Objective: We investigated the association between five endocrine-disrupting heavy metals (EDHMs), i.e., arsenic (As), cadmium (Cd), lead (Pb), mercury (Hg), and tin (Sn), in maternal hair and the risk of GDM.

Methods: We conducted a nested case-control study including 335 GDM cases and 343 controls without GDM based on a prospective birth cohort established in Beijing, China. Concentrations of EDHMs were analyzed in maternal hair. Log-binomial regression and multiple linear regression were used to estimate the associations between the hair concentrations of single metals and the risk of GDM, while weighted quantile sum (WQS) regression for their mixed effects.

Results: The median concentrations of Hg (0.442 vs. 0.403 μg/g) and Sn (0.171 vs. 0.140 μg/g) in the case group were significantly higher than those in the control group. No differences were found between the two groups for the other three metals. After adjusting for confounders, the prevalence ratio (PR; highest vs. lowest tertile) of GDM risk for Hg was 1.27 (95% confidence interval [CI]: 1.05-1.54), while that for Sn was 1.26 (95% CI: 1.04-1.53). Among women with a body mass index < 24 kg/m, the PR (highest vs. lowest tertile) of GDM for Sn was 1.38 (95% CI: 1.09-1.75). The effect of exposure to the five EDHMs on the risk of GDM was estimated by WQS regression: Sn and Hg made the largest contributions to the WQS index (40.9% and 40.3%, respectively).

Conclusion: High maternal levels of EDHMs, particularly Sn and Hg, may promote the development of GDM.
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http://dx.doi.org/10.1016/j.envint.2021.106770DOI Listing
July 2021

Associations between blood heavy metal(loid)s and serum heme oxygenase-1 in pregnant women: Do their distribution patterns matter?

Environ Pollut 2021 Oct 29;286:117249. Epub 2021 Apr 29.

Institute of Reproductive and Child Health, Peking University/ Key Laboratory of Reproductive Health, National Health Commission of the People's Republic of China, Beijing, 100191, PR China; Department of Epidemiology and Biostatistics, School of Public Health, Peking University, Beijing, 100191, PR China.

The relationship between heavy metal(loid)s exposure and oxidative stress damage is a matter of research interest. Our study aimed to investigate the distribution patterns of the nine heavy metal(loid)s in blood of pregnant women, including four toxic heavy metal(loid)s [arsenic (As), cadmium (Cd), lead (Pb) and mercury (Hg)] and five typical heavy metal(loid)s [manganese (Mn), cobalt (Co), copper (Cu), zinc (Zn), and selenium (Se)] in blood. Blood samples of 348 women were collected and their concentrations in the serum (sr) and blood cells (bc) were measured, as well as serum heme oxygenase-1 (HO-1) (an oxidative stress marker). Total blood (tb) concentrations of these metal(loid)s and serum-to-blood cell concentration ratios (sr/bc) were further calculated. We found Cu mainly accumulated in the serum compared to the blood cells with Cu = 2.30, whereas Co, Se, and As evenly distributed between these two fractions. Other metal(loid)s mainly concentrated in the blood cells. Co, Cu, Cu, Mn, Zn, Cd, Co, Cu, Mn, Zn, Cd, and Cu were negatively associated with serum HO-1, whereas As, As, As, Zn, Cd, and Hg were positively, indicating of their potential toxicity. We concluded that the distribution patterns of blood heavy metal(loid)s, in particular for Cd, Hg and Zn, which either increased in serum or decreased in blood cells, might be associated with elevated serum oxidative stress, should be considered in environmental health assessments.
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http://dx.doi.org/10.1016/j.envpol.2021.117249DOI Listing
October 2021

Distribution of mercury in serum and blood cells and risk of spontaneous preterm birth: A nested case-control study in China.

Ecotoxicol Environ Saf 2021 Jul 20;217:112228. Epub 2021 Apr 20.

Institute of Geographic Sciences and Natural Resources Research, CAS, Beijing 100101, PR China. Electronic address:

The relationship between maternal mercury (Hg) intake and the risk of spontaneous preterm birth (SPB) remains unclear. We conducted a nested case-control study from a prospective cohort in Shanxi Province, China, to explore their associations. In total, 126 pregnant women with SPB (cases) and 348 controls with term delivery were included. We measured the Hg concentrations in their serum (Hg) and blood cell (Hg) fractions and calculated the concentration ratio of Hg in serum to Hg in blood cells (Hg). We found that only the Hg in the case group was slightly higher than that in control group. The OR of Hg associated with SPB risk was 1.57 [95%CI: 0.99-2.46] with adjusting confounders. After stratification by sampling time, the association above was only statistically significant in the first trimester. High Hg may increase the risk of SPB in the first trimester among women with relatively low Hg exposure.
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http://dx.doi.org/10.1016/j.ecoenv.2021.112228DOI Listing
July 2021

Impact of gestational hypertension and preeclampsia on low birthweight and small-for-gestational-age infants in China: A large prospective cohort study.

J Clin Hypertens (Greenwich) 2021 04 28;23(4):835-842. Epub 2021 Jan 28.

Institute of Reproductive and Child Health, Chinese National Health Commission Key Laboratory of Reproductive Health, Peking University Health Science Center, Beijing, China.

Studies have shown that maternal blood pressure level is associated with neonatal birthweight, but the results are not exactly consistent. As the most common hypertensive disorders during pregnancy, the mechanism of gestational hypertension and pre-eclampsia that affect fetal growth remain unclear. Our objective was to examine the association of gestational hypertension and pre-eclampsia with the risk of low birthweight (LBW) and small-for-gestational-age (SGA). Data were obtained from the China-US Collaborative Project for Neural Tube Defects Prevention, a large population-based cohort study. We selected participants who were registered in two southern provinces, had exact information on gestational blood pressure and pregnancy outcomes, and were not affected by chronic hypertension. Logistic regression was used to adjust for the effects of the main potential confounders, including age, body mass index, education, occupation, ethnicity, folic acid use, and parity. The overall incidences of LBW and SGA were 2.25% and 5.86%, respectively. The incidences of LBW/SGA were 3.58%/7.58% and 6.02%/10.67% for gestational hypertension and pre-eclampsia group, relative to 2.11%/5.68% and 2.16%/5.74% for normal group. The adjusted odds ratios associated with gestational hypertension/pre-eclampsia were 1.77 (95% CI: 1.63, 1.92)/3.01 (95% CI: 2.67, 3.40) for LBW and 1.40 (95% CI: 1.32, 1.48)/2.02 (95% CI: 1.84, 2.22) for SGA, respectively. The early onset of gestational hypertension/pre-eclampsia appeared to be a relatively more detrimental exposure window for both LBW and SGA. Our results support an association between gestational hypertension or pre-eclampsia and the increased risk of LBW and SGA.
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http://dx.doi.org/10.1111/jch.14176DOI Listing
April 2021

Precipitation controls seed bank size and its role in alpine meadow community regeneration with increasing altitude.

Glob Chang Biol 2020 Oct 22;26(10):5767-5777. Epub 2020 Jul 22.

State Key Laboratory of Grassland and Agro-ecosystems, School of Life Sciences, Lanzhou University, Lanzhou, P.R. China.

The Tibetan Plateau has undergone significant climate warming in recent decades, and precipitation has also become increasingly variable. Much research has explored the effects of climate change on vegetation on this plateau. As potential vegetation buried in the soil, the soil seed bank is an important resource for ecosystem restoration and resilience. However, almost no studies have explored the effects of climate change on seed banks and the mechanisms of these effects. We used an altitudinal gradient to represent a decrease in temperature and collected soil seed bank samples from 27 alpine meadows (3,158-4,002 m) along this gradient. A structural equation model was used to explore the direct effects of mean annual precipitation (MAP) and mean annual temperature (MAT) on the soil seed bank and their indirect effects through aboveground vegetation and soil environmental factors. The species richness and abundance of the aboveground vegetation varied little along the altitudinal gradient, while the species richness and density of the seed bank decreased. The similarity between the seed bank and aboveground vegetation decreased with altitude; specifically, it decreased with MAP but was not related to MAT. The increase in MAP with increasing altitude directly decreased the species richness and density of the seed bank, while the increase in MAP and decrease in MAT with increasing altitude indirectly increased and decreased the species richness of the seed bank, respectively, by directly increasing and decreasing the species richness of the plant community. The size of the soil seed bank declined with increasing altitude. Increases in precipitation directly decreased the species richness and density and indirectly decreased the species richness of the seed bank with increasing elevation. The role of the seed bank in aboveground plant community regeneration decreases with increasing altitude, and this process is controlled by precipitation but not temperature.
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http://dx.doi.org/10.1111/gcb.15260DOI Listing
October 2020

Environmental titanium exposure and reproductive health: Risk of low birth weight associated with maternal titanium exposure from a nested case-control study in northern China.

Ecotoxicol Environ Saf 2021 Jan 18;208:111632. Epub 2020 Nov 18.

Institute of Reproductive and Child Health, Peking University/Key Laboratory of Reproductive Health, National Health Commission of the People's Republic of China, Beijing 100191, PR China; Department of Epidemiology and Biostatistics, School of Public Health, Peking University, Beijing 100191, PR China.

Titanium (Ti) is commonly used in additives in the form of titanium dioxide (TiO). However, our understanding of the effect of Ti on reproductive health remains limited. This nested case-control study, performed in a Ti mining exposure field, investigated the association between maternal blood Ti concentration and the risk of low birth weight (LBW), as well as the potential biological mechanism. A total of 45 women who delivered LBW infants (cases) and 352 women with normal birth weight infants (controls) were included. We collected maternal peripheral blood samples in the first or early second trimester to measure Ti concentration in serum (Ti) and blood cells (Ti), as well as inflammatory, lipid, and oxidative stress biomarkers thereof. The demographic characteristics of the women included in the study were also obtained. The results showed that the median total blood Ti concentration (Ti) in the case group was significantly higher than that in the control group (134 vs. 129 ng/mL, P = 0.039). A higher Ti level was associated with a greater risk of LBW [odds ratio = 2.62; 95% confidence interval (CI): 1.16-5.90], but no such association was observed for Ti or Ti after adjusting for potential confounders. The serum lipid biomarkers TC, TG, and total lipids (TL) were all negatively associated with Ti and Ti. Serum 8-OHdG was positively associated with Ti. We concluded that a high Ti during early pregnancy may increase the risk of LBW. Lipid metabolism and oxidative stress may play an important role in the adverse health effects associated with Ti exposure. Thus, our results merit more attention to the probable adverse effects of titanium exposure during pregnancy.
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http://dx.doi.org/10.1016/j.ecoenv.2020.111632DOI Listing
January 2021

Potential interference on the lipid metabolisms by serum copper in a women population: A repeated measurement study.

Sci Total Environ 2021 Mar 1;760:143375. Epub 2020 Nov 1.

Institute of Reproductive and Child Health, Peking University, Beijing 100191, PR China; Department of Epidemiology and Biostatistics, School of Public Health, Peking University, Beijing 100191, PR China; Key Laboratory of Reproductive Health, National Health Commission of the People's Republic of China, Beijing 100191, PR China. Electronic address:

The relationship between excess copper (Cu) intake and lipid metabolic disorders is not well-studied, and most studies on this topic have a cross-sectional design. Here, we investigated the relationship between Cu exposure and blood lipid metabolism in women population, as well as potential mediation effects of oxidative stress and inflammation, using a repeated-measurement study. A total of 35 women in northern China were included, and each individual was visited for five times. Blood samples were collected, and the following serum biomarkers were analyzed: heme oxygenase-1 (HO-1), monocyte chemotactic protein-1 (MCP-1), interleukin (IL)-6, IL-8, and lipids [triglycerides (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL), high-density lipoprotein cholesterol (HDL), and lipoprotein(a) (Lp(a))]. A linear mixed-effect model was used to analyze the associations between Cu and the individual biomarkers in serum. The results showed that Cu was positively associated with TG (β = 0.0007, P = 0.01), TC (β = 0.0006, P = 0.002), LDL (β = 0.0004, P ≤ 0.001), and Lp(a) (β = 0.0004, P = 0.01), but not associated with HDL (β = 0.0001, P = 0.19). Likewise, serum Cu was positively associated with HO-1 (β = 0.0004, P = 0.03) and negatively associated with MCP-1 (β = -0.0006, P = 0.003) and IL-8 (β = -0.002, P = 0.03). Among the biomarkers of oxidative stress, inflammation, and lipids in serum, only IL-8 was negatively associated with HDL (β = -0.0004, P = 0.009). No other associations were observed. We conclude that high Cu exposure may elevate blood lipid levels as well as disturb processes related to oxidative stress and inflammation responses.
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http://dx.doi.org/10.1016/j.scitotenv.2020.143375DOI Listing
March 2021

Preconception blood pressure and risk of gestational hypertension and preeclampsia: a large cohort study in China.

Hypertens Res 2020 09 22;43(9):956-962. Epub 2020 Apr 22.

Institute of Reproductive and Child Health/Ministry of Health Key Laboratory of Reproductive Health, Peking University Health Science Center, Beijing, China.

Our objective was to examine whether high blood pressure in the preconception period was associated with gestational hypertension and preeclampsia in Chinese women. Data were obtained from the China-US Collaborative Project for Neural Tube Defects Prevention, a large population-based cohort study. We included 45,628 women who were registered before pregnancy in seven counties in South China. Blood pressure was measured during registration by trained health care workers, and other health-related information was recorded prospectively. We used logistic regression to evaluate the associations between preconception blood pressure and the risk of gestational hypertension and preeclampsia, adjusting for potential confounders. The prevalence of hypertension in the preconception study population was 4.57% (2083/45,628). The incidences of gestational hypertension and preeclampsia were 11.95% and 4.08%, respectively, in the hypertension group and 8.60% and 2.28%, respectively, in the nonhypertension group. Compared with the nonhypertension group, the hypertension group showed a significantly increased risk for gestational hypertension [adjusted risk ratio (RR) = 1.40, 95% confidence interval (CI): 1.22-1.60] and preeclampsia [adjusted RR = 1.75, 95% CI: 1.39-2.19]. When participants with normal blood pressure were used as the reference, the adjusted ORs for gestational hypertension were 1.48 (95% CI: 1.37-1.59), 1.70 (95% CI: 1.44-2.01), and 1.29 (95% CI: 1.02-1.64), and for preeclampsia, the adjusted ORs were 1.55 (95% CI: 1.35-1.78), 1.95 (95% CI: 1.46-2.60), and 1.99 (95% CI: 1.39-2.85) for the participants with prehypertension, stage 1 hypertension, and stage 2 hypertension, respectively. Our results support an association between hypertension or higher blood pressure prior to pregnancy and an increased risk of gestational hypertension and preeclampsia.
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http://dx.doi.org/10.1038/s41440-020-0438-9DOI Listing
September 2020

The impact of preconception body mass index on cervical length: a prospective cohort study in China.

J Matern Fetal Neonatal Med 2019 Dec 18:1-5. Epub 2019 Dec 18.

Institute of Reproductive and Child Health/Ministry of Health, Key Laboratory of Reproductive Health, Peking University Health Science Center, Beijing, China.

To assess the relationship between preconception body mass index (BMI) and cervical length (CL). Data was collected from a prospective cohort study conducted in Beijing, China. A total of 4843 qualified women participated in this study, whose health-related information was recorded at the very beginning and their cervical length was measured with transvaginal ultrasound examination during 22-24 gestational weeks. Logistic regression was used to evaluate the relationship between preconception BMI and cervical length, after adjusting for potential confounders. Of all the participants in the analysis, 580 (12.0%) women had a short cervical length (CL less than 30 mm). After adjusting for the age and parity status, the adjusted odds ratios of short CL for underweight: adjusted OR = 1.28 (95% CI: 1.02, 1.60); overweight: adjusted OR = 0.74 (95% CI: 0.55, 0.99); obesity: adjusted OR = 0.38 (95% CI: 0.17, 0.88) compared with normal weight. The mean CL in underweight, normal weight, overweight and obesity group demonstrated a significant linear increased trend (33.47, 34.16 and 34.96 mm, respectively) ( < .05), dependent of age and parity. This research revealed that low preconception BMI women were more likely to have a short CL.
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http://dx.doi.org/10.1080/14767058.2019.1704245DOI Listing
December 2019

Comparative systems biology reveals allelic variation modulating Tocochromanol profiles in Barley (Hordeum vulgare L.).

PLoS One 2014 12;9(5):e96276. Epub 2014 May 12.

Crop Biosciences, General Mill, Inc., Kannapolis, North Carolina, United States of America, formerly USDA-ARS, Small Grains and Potato Germplasm Research Unit, Aberdeen, Idaho, United States of America.

Tocochromanols are recognized for nutritional content, plant stress response, and seed longevity. Here we present a systems biological approach to characterize and develop predictive assays for genes affecting tocochromanol variation in barley. Major QTL, detected in three regions of a SNP linkage map, affected multiple tocochromanol forms. Candidate genes were identified through barley/rice orthology and sequenced in genotypes with disparate tocochromanol profiles. Gene-specific markers, designed based on observed polymorphism, mapped to the originating QTL, increasing R2 values at the respective loci. Polymorphism within promoter regions corresponded to motifs known to influence gene expression. Quantitative PCR analysis revealed a trend of increased expression in tissues grown at cold temperatures. These results demonstrate utility of a novel method for rapid gene identification and characterization, and provide a resource for efficient development of barley lines with improved tocochromanol profiles.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0096276PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4018352PMC
January 2015

Suppression of Root-knot Nematode Populations with Selected Rapeseed Cultivars as Green Manure.

J Nematol 1991 Apr;23(2):170-4

Meloidogyne chitwoodi races 1 and 2 and M. hapla reproduced on 12 cultivars of Brassica napus and two cultivars of B. campestris. The mean reproductive factors (Rf), Rf = Pf at 55 days / 5,000, for the three nematodes were 8.3, 2.2, and 14.3, respectively. All three nematodes reproduced more efficiently (P < 0.05) on B. campestris than on B. napus. Amending M. chitwoodi-infested soil in plastic bags with chopped shoots of Jupiter rapeseed reduced the nematode population more (P < 0.05) than amendment with wheat shoots. Incorporating Jupiter shoots to soil heavily infested with M. chitwoodi in microplots reduced the nematode population more (P < 0.05) than fallow or corn shoot treatments. The greatest reduction in nematode population density was attained by cropping rapeseed for 2 months and incorporating it into the soil as a green manure.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2619149PMC
April 1991
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