Chronic intermittent hypoxia (IH) contributes to obstructive sleep apnea (OSA)-related cardiovascular diseases through increasing oxidative stress. It has been widely recognized that estradiol decreases the risk for cardiovascular disease, but the estrogen replacement therapy is limited for its side effects. Thioredoxin (Trx) and its endogenous inhibitor, thioredoxin-interacting protein (Txnip), are associated with the protective effect of estradiol in some conditions. In this study, we aimed to explore whether estradiol could protect against IH-induced vascular injury, and the possible effect of Trx-1/Txnip in this process. Forty-eight adult female C57/BL6J mice were randomly divided into 4 groups, ovariectomy combined with IH group, sham operation combined with IH group, IH group and the control group. The mice treated with IH for 8 hrs/day, and 28 days. IH induced the injury of aorta, and ovariectomized mice were more prone to the IH-induced aortic injury, with higher level of oxidative stress. In vitro, estradiol increased Trx-1 level, but decreased the level of Txnip and oxidative stress in human umbilical vein endothelial cells (HUVECs) treated with IH for 16 hrs. Knock-down of Txnip by specific siRNA rescued oxidative stress and apoptosis. In conclusion, estradiol protects against IH-induced vascular injury, partially through the regulation of Trx-1/Txnip pathway.

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The boehmite (AlOOH) sol derived from aluminium isopropoxide was synthesized by Yoldas method. The physicochemical process and phase transition of AlOOH were investigated by TG-DSC, N2 adsorption-desorption, XRD and TEM. The results showed that upon heating, AlOOH lost the physicsorbed water first, and then lost the chemisorbed water at 242 °C, and the dehydroxylation occurred at 361 °C. The BET surface area, total pore volume and pore diameter increased, since the waters were lost. The orthorhombic AlOOH transformed to the cubic γ-Al2O3 at 361 °C, the cubic η-Al2O3 appeared after 484 °C, the monoclinic θ-Al2O3 and rhombohedral α-Al2O3 appeared after 1026 °C, and it totally turned into α-Al2O3 at 1237 °C.