Exposure to Asian dust within a few days of delivery is associated with placental abruption in Japan: a case-crossover study

OBJECTIVE

Asian dust is a natural phenomenon in which dust particles are transported from desert areas in China and Mongolia to East Asia. Short-term exposure to Asian dust has been associated with cardiovascular disease through mechanisms such as systemic inflammation. Because inflammation is a potential trigger of placental abruption, exposure may also lead to abruption. We examined whether exposure to Asian dust was associated with abruption.

DESIGN

A bi-directional, time-stratified case-crossover design.

SETTING AND POPULATION

From the Japan Perinatal Registry Network database, we identified 3014 patients who delivered singleton births in hospitals in nine Japanese prefectures from 2009 to 2014 with a diagnosis of placental abruption.

METHODS

Asian dust levels were measured at Light Detection and Ranging monitoring stations, and these measurements were used to define the Asian dust days. As there was no information on the onset day of abruption, we assumed this day was the day before delivery (lag1).

MAIN OUTCOME MEASURES

Placental abruption.

RESULTS

During the study period, the Asian dust days ranged from 15 to 71 days, depending on the prefecture. The adjusted odds ratio of placental abruption associated with exposure to Asian dust was 1.4 (95% confidence interval = 1.0, 2.0) for cumulative lags of 1-2 days. Even after adjustment for co-pollutant exposures, this association did not change substantially.

CONCLUSIONS

In this Japanese multi-area study, exposure to Asian dust was associated with an increased risk of placental abruption.

TWEETABLE ABSTRACT

Exposure to environmental factors such as Asian dust may be a trigger of placental abruption.

Inhibition of AHR transcription by NF1C is affected by a single-nucleotide polymorphism, and is involved in suppression of human uterine endometrial cancer

Involvement of the aryl hydrocarbon receptor (AHR) in carcinogenesis has been suggested in many studies. Upregulation of AHR has been reported in some cancer species, and an association between single-nucleotide polymorphisms (SNPs) of AHR and cancer risk or cancer development has also been reported. This evidence suggests the involvement of some specific SNPs in AHR transcriptional regulation in the process of carcinogenesis or cancer development, but there have been no studies to elucidate the mechanism involved. In this study, we identified the transcription factor Nuclear Factor 1-C (NF1C) as a candidate to regulate AHR transcription in a polymorphism-dependent manner. SNP rs10249788 was included in a consensus binding site for NF1C. Our results suggested that NF1C preferred the C allele to the T allele at rs10249788 for binding. Forced expression of NF1C suppressed the activity of the AHR promoter with C at rs10249788 stronger than that with T. Moreover, expression analysis of human uterine endometrial cancer (HEC) specimens showed greater upregulation of AHR and downregulation of NF1C than those of normal endometrium specimens. Sequence analysis showed HEC patients at advanced stages tended to possess T/T alleles more frequently than healthy women. We also demonstrated that NF1C suppressed proliferation, motility and invasion of HEC cells. This function was at least partially mediated by AHR. This study is the first to report that a polymorphism on the AHR regulatory region affected transcriptional regulation of the AHR gene in vitro. Because NF1C is a tumor suppressor, our new insights into AHR deregulation and its polymorphisms could reveal novel mechanisms of genetic susceptibility to cancer.

Effect of transient TCDD exposure on immortalized human trophoblast-derived cell lines

Low level, antenatal exposure to dioxins is associated with low birth weight, which in turn is associated with long-term sequelae. We exposed the human extravillous cytotrophoblast (EVT) lines HTR-8/SV40 and TCL1 to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and assessed cell growth, invasion, and differentiation. TCDD had no effect on cell proliferation, invasion, or tube formation in Matrigel. The EVT-derived cells expressed a functional aryl hydrocarbon receptor protein; however, TCDD exposure did not alter expression levels of proteins involved in EVT differentiation in early pregnancy, including hypoxia-inducible factor 1A (HIF1A), vascular endothelial growth factor (VEGF), Integrin A1, A6, and AVB3. These results suggest that the reduction in fetal weight induced by dioxin is not the result of vascular remodeling via EVT dysfunction.

Diurnal changes in the power spectral characteristics of eye movements and heart rate variability in the human fetus at term

It is well known that 1/f characteristics in power spectral patterns exist in various biological factors including heart rate variability. In the present study, we tried to elucidate the diurnal variation in spectral properties of eye movement and heart rate variability in the human fetus at term, via continuous 24-h observation of both these parameters. Studied were five uncomplicated fetuses at term. We observed eye movement and fetal heart rate (FHR) with real-time ultrasound and Doppler cardiotocograph, respectively, and analyzed the diurnal change in spectral properties, using the maximum entropy method. In four of five cases, the slope values of power spectra for both eye movement frequency and FHR, ranging approximately between 0.5 and 1.8, indicated diurnal variation, where the slopes tended to have high values during the day and low values at night. These findings suggest that, in the human fetus at term, eye movement and FHR are under the control of a common central mechanism, and this center changes its complexity as seen through diurnal rhythm.

Diurnal variation of eye movement and heart rate variability in the human fetus at term

To elucidate diurnal variations in eye movement and fetal heart rate (FHR) variability in the term fetus, we observed these two parameters continuously for 24 h, using real-time ultrasound and Doppler cardiotocograph, respectively. Studied were five uncomplicated fetuses at term. The time series data of the presence and absence of eye movement and mean FHR value for each 1 min were analyzed using the maximum entropy method (MEM) and subsequent nonlinear least squares fitting. According to the power value of eye movement, all five cases were classified into two groups: three cases in the large power group and two cases in the small power group. The acrophases of eye movement and FHR variability in the large power group were close, thereby implying the existence of a diurnal rhythm in both these parameters and also that they are synchronized. In the small power group, the acrophases were separated. The synchronization of eye movement and FHR variability in the large power group suggests that these phenomena are governed by a common central mechanism related to diurnal rhythm generation.