Calcitriol reverses age-related hypertension via downregulating renal AP1/AT1R pathway through regulating mitochondrial function.

BACKGROUND: The vitamin D level in the blood is associated with the incidence of hypertension. The present study investigated whether or not calcitriol, an active form of vitamin D, reverses age-related hypertension. METHODS: Young (3-month-old) and aged (12-month-old) C57BL/6 male mice were administered with or without calcitriol at 150 ng/kg per day by oral gavage for 8 weeks. Blood pressure was measured by tail-cuff plethysmography and telemetry, and superoxide production in renal tissue was assessed by fluorescence imaging, and the protein expression of AP1/AT1R signaling pathway was examined by Western blot. RESULTS: We showed that 24-hour renal sodium excretion was impaired and blood pressure was increased in aged mice, which was related to the enhancement of renal AT1R expression and function. In addition, the expression of transcription factor AP1 (a dimer of c-Fos and c-Jun) and the binding of AP1 to the AT1R promoter region was significantly enhanced, accompanied by decreased nuclear translocation of Nrf2, abnormal mitochondrial function including decreased ATP production, NAD+/NADH ratio and mtDNA copy numbers, and increased reactive oxygen species. Calcitriol increased 24-hour urinary sodium excretion and reduced blood pressure in aged mice. Mechanically, calcitriol increased the nuclear translocation of Nrf2, improved mitochondrial function, reduced AP1 binding ability to AT1R promoter, which reversed enhanced AT1R expression and function, and lowered blood pressure in aged mice. CONCLUSIONS: Our findings indicated that calcitriol reversed age-related hypertension via downregulating renal AP1/AT1R pathway through regulating mitochondrial function. Thus, calcitriol may be a valuable therapeutic strategy for age-related hypertension.

Improving the adsorption performance of urea by using polyhydroxy groups to modify two-dimensional Ti3C2Tx.

Wearable artificial kidney can provide continuous dynamic dialysis for uremia patients. For the sake of practical application, the critical step is to find an adsorbent that can effectively remove urea and have excellent biological compatibility. The layered Ti3C2Tx (DL-Ti3C2Tx) with high specific surface area and good dispersion was prepared by a two-step etching method. From the first principles calculation, urea can be adsorbed by different groups (-F, -O, -OH) on the surface of Ti3C2Tx, among which -OH has the greatest binding energy to urea. Therefore, DL-Ti3C2Tx was modified with different alkali solutions (KOH, NaOH, LiOH) to introduce -OH on the surface, which can increase the adsorption capacity of urea. The experimental results showed that DL-Ti3C2Tx (LiOH-Ti3C2Tx) after treated by LiOH had the highest urea adsorption efficiency, and the urea removal rate of LiOH-Ti3C2Tx was still higher than 92% when the urea concentration was 500 mg/L. In the Simulated dialysate, Ti3C2Tx treated with three kinds of alkali solutions still maintained a good adsorption efficiency for urea, and still had a certain adsorption capacity after recycling for four times. Biocompatibility experiments showed that Ti3C2Tx in different concentrations did not cause hemolysis of erythrocyte, and had no obvious damage to vascular endothelial cells. This study greatly improves the urea adsorption efficiency of MXene, which has a broad application prospect in the selection of adsorbent for wearable artificial kidney.

Macroporous honeycomb-like magnesium oxide fabricated as long-life and outstanding Pb(II) adsorbents combined with mechanism insight.

The macroporous honeycomb-like MgO (MHM) had been successfully prepared by hard template method using polystyrene (PS) spheres with different particle sizes of about 400, 600, and 800 nm, respectively. The adsorption performance (3700, 3470, and 3087 mg/g) and specific surface areas (64.0, 51.4, and 34.4 m2/g) of MHM materials were inversely proportional to their pore diameters. Among the prepared MHM materials, MHM-400 exhibited the most excellent adsorption performance of 3700 mg/g towards Pb(II) at 25 °C. In this study, the macropore size in MHM played a major role in the adsorption process; Dubinin-Radushkevich (D-R) model further indicated that Pb(II) removal by MHM-400 was dominated by chemical adsorption. The thermodynamic analysis (ΔG0 < 0, ΔH0 > 0, and ΔS0 > 0) revealed that the Pb(II) adsorption was spontaneous and endothermic. After storing for 360 days, the Pb(II) removal efficiency of MHM-400 was still higher than 98.2%, exhibiting ultra-long life for Pb(II) capture. MHM-400 also exhibited high anti-interference ability towards typically coexisting ions (Na+ and K+). According to the density functional theory (DFT) calculation, the Pb could be adsorbed on the top site of the oxygen atom at the surface of the cubic MgO (200) plane; the adsorption energy (Ead) was 0.159 eV. The XRD and FTIR analyses revealed the further formation of Pb3(CO3)2(OH)2 and PbO after Pb(II) adsorption. Furthermore, MHM-400 could effectively remove both Cd(II) and Pb(II) ions from wastewater within 20 min, and the adsorption efficiency achieved > 99%, suggesting that MHM-400 was a potential material for effective Pb(II) removal.

Enhanced removal of ammonia nitrogen from rare earth wastewater by NaCl modified vermiculite: Performance and mechanism.

Wastewater from rare earth mining (WREM) is very harmful to environment and human health due to its high concentration of ammonia nitrogen (NH3-N). It is therefore necessary and urgent to find a low-cost and convenient technique to remove high concentration of NH3-N from WREM. In this study, Natural powdered vermiculite (NV) was modified with seven sodium chloride (NaCl) solutions, and seven kinds of sodium chloride modified vermiculite (Na-V) were obtained. The NH3-N adsorption performance of Na-V is greatly improved compared with NV. Among them, vermiculite modified with 180 g/L NaCl yielded the highest ammonium adsorption capacity (Qm, 11.569 mg/g), which was 63.43% higher than NZ (Qm, 7.079 mg/g). The characterizations of 180-Na-V confirmed the removal mechanism of NH3-N that the improved capacity of modified vermiculite was attributed to its higher mesoporous volume and ion-exchange capacity, which are the result of sodium-ion exchange and Interlayer effect from high concentration of NaCl. The adsorption isotherms and kinetics were respectively best consistent with Langmuir model and the pseudo-second-order (PSO) model. The adsorption capacity (3.808 mg/g) of vermiculite after 5 cycles could still maintain 75.09% of the initial adsorption capacity (5.071 mg/g). A large amount of Na-V had little effect on pH of water, which meet the requirements of practical application. Including pH, dosage, coexisting ions, the effects of other factors on ammonium adsorption were also determined. This study provides a new method for vermiculite to remove high concentration of NH3-N.

Template synthesis of ordered mesoporous MgO with superior adsorption for Pb(II) and Cd(II).

Ordered mesoporous MgO was synthesized via template method by using magnesium nitrate as a precursor and amphiphilic triblock copolymer Pluronic F127 as a template. The products were characterized by X-ray powder diffraction (XRD) and transmission electron microscopy (TEM), and the Brunauer-Emmett-Teller (BET) method was used to calculate the specific surface areas. The effects of aging time, relative humidity, and magnesium nitrate content on the morphology and textural properties of the products were studied. When the aging time was 36 h and the relative humidity was 40%, the ordered mesoporous MgO with uniform pore sizes (3.2 nm), high specific surface areas (517.2 m2/g), and high pore volumes (0.42 cm3/g) were obtained. Furthermore, the adsorption properties of ordered mesoporous MgO as adsorbent for removal of Pb(II) and Cd(II) ions were studied. The adsorption kinetics and isotherm data agreed well with pseudo-second-order model and Langmuir model, indicating that the adsorption of heavy metal ions on the ordered mesoporous MgO was mainly chemical and homogeneous adsorption. The maximum adsorption capacities for Pb(II) and Cd(II) ions were up to 3073.5 mg/g and 1485.1 mg/g, respectively.

Facile synthesis of hollow mesoporous MgO spheres via spray-drying with improved adsorption capacity for Pb(II) and Cd(II).

Spherical-like MgO nanostructures have been synthesized efficiently via spray-drying combined with calcination using magnesium acetate as magnesium source. The products were characterized by means of X-ray powder diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and the specific surface areas were calculated using the Brunauer-Emmett-Teller (BET) method. The obtained spherical-like MgO nanostructures exhibit uniform pore sizes (7.7 nm) and high specific surface areas (180 m2 g-1). The adsorption kinetics and isotherm data agree well with pseudo-second-order model and Langmuir model, indicating the monolayer chemisorption of heavy metal ions. The spherical-like MgO nanostructures exhibited high adsorption performance for Pb(II) and Cd(II) ions, and the maximum adsorption capacities were up to 5214 mg g-1 and 4187 mg g-1, respectively. These values are much higher than those reported MgO-based adsorbents. Moreover, in less than 10 min, Pb(II) and Cd(II) ions in solution can be almost removed, which means that the spherical-like MgO possesses a high adsorption rate. XRD and FTIR analysis revealed the adsorption mechanism of Pb(II) and Cd(II) ions on MgO, which was mainly due to hydroxyl functional groups and ion exchange between Mg and heavy metal ions on the surface of MgO. These favorable performances recommend that the synthesized spherical-like MgO nanostructures would be a potential adsorbent for rapid removal of heavy metal ions from wastewater.

Facile synthesis of hierarchical hollow mesoporous Ag/WO3 spheres with high photocatalytic performance.

Hollow mesoporous tungsten trioxide spheres (HMTTS) have been synthesized by spray drying method combined with proper calcination and Ag/HMTTS are prepared on the basis of a silver mirror reaction. HMTTS are composed of nanoparticles with diameter of 20-70 nm. The accumulation of nanoparticles generates pores with the mean pore size of about 45 nm. The formation mechanism of hollow mesoporous structure is studied in this work. Ag in WO3 narrows the band gap and derceases the recombination possibility of the photogenerated electron-hole pairs, which enhance photocatalytic activity of Ag/WO3 composites. The degradation rate of methylene blue is 98.16% under UV light illumination for 75 min and 49.07% under visible light irradiation for 150 min by Ag/WO3 composites.