Enhanced Nitrite-Mediated Relaxation of Placental Blood Vessels Exposed to Hypoxia Is Preserved in Pregnancies Complicated by Fetal Growth Restriction

Nitric oxide (NO) is essential in the control of fetoplacental vascular tone, maintaining a high flow−low resistance circulation that favors oxygen and nutrient delivery to the fetus. Reduced fetoplacental blood flow is associated with pregnancy complications and is one of the major causes of fetal growth restriction (FGR). The reduction of dietary nitrate to nitrite and subsequently NO may provide an alternative source of NO in vivo. We have previously shown that nitrite induces vasorelaxation in placental blood vessels from normal pregnancies, and that this effect is enhanced under conditions of hypoxia. Herein, we aimed to determine whether nitrite could also act as a vasodilator in FGR. Using wire myography, vasorelaxant effects of nitrite were assessed on pre-constricted chorionic plate arteries (CPAs) and veins (CPVs) from normal and FGR pregnancies under normoxic and hypoxic conditions. Responses to the NO donor, sodium nitroprusside (SNP), were assessed in parallel. Nitrate and nitrite concentrations were measured in fetal plasma. Hypoxia significantly enhanced vasorelaxation to nitrite in FGR CPAs (p < 0.001), and in both normal (p < 0.001) and FGR (p < 0.01) CPVs. Vasorelaxation to SNP was also potentiated by hypoxia in both normal (p < 0.0001) and FGR (p < 0.01) CPVs. However, compared to vessels from normal pregnancies, CPVs from FGR pregnancies showed significantly lower reactivity to SNP (p < 0.01). Fetal plasma concentrations of nitrate and nitrite were not different between normal and FGR pregnancies. Together, these data show that nitrite-mediated vasorelaxation is preserved in FGR, suggesting that interventions targeting this pathway have the potential to improve fetoplacental blood flow in FGR pregnancies.     

DFT Study to Reduce TCDD by B12N12 Nano-Cage: A Comparison of Calculating Spectroscopic Properties with NMR and NBO

ABSTRACT

According to human studies, one of the most hazardous chlorinated organic compounds is tetrachlorodibenzodioxin (TCDD). These studies have found an association between TCDD and lung cancer, soft-tissue sarcomas, lymphomas, stomach carcinomas, and so on. One of the aims of this research is to identify and reduce these pollutants by boron nitride nano-cages (B₁₂N₁₂-NC) with T_h symmetry. First, the sensitivity of B₁₂N₁₂-NC is investigated for two types of TCDD (2,3,7,8-TCDD and 1,3,7,9-TCDD) using GAMESS-US program package with B3LYP/6–31++G(d) levels. According to the calculated data, B₁₂N₁₂-NC is more sensitive to 1,3,7,9-TCDD. Then, it is simulated to calculate the geometric optimize structure, electronic properties, thermodynamics properties; nuclear magnetic resonance studies and the natural bonding orbital analysis are conducted separately for B₁₂N₁₂-NC and 1,3,7,9-TCDD, and when closed TCDD approaches nano-cage, steps of its conversion into intermediate (2,4-dichlorophenol) and finally to aliphatic compound (2-chloroprop-2-en-ol and 1-chloropropene) are shown. According to the results, most changes are observed in the transition state of these interactions, which indicates that the nano-adsorbent (B₁₂N₁₂-NC) is suitable for identifying and reducing dioxin compounds.