Determination of uric acid in biological samples by high performance liquid chromatography-electrospray ionization-tandem mass spectrometry and study on pathogenesis of pulmonary arterial hypertension in pulmonary artery endothelium cells

Pulmonary arterial hypertension (PAH) is a severe cardiovascular disease that can lead to vascular remodelling and hypertension. Clinical diagnosis of PAH is very difficult. Uric acid (UA) can act as a biological marker for screening of PAH in patients. Multiple studies have indicated that reactive oxygen species (ROS) play an important role in the development of PAH. Thus, it is important to study the relationship between UA and ROS based on the pathogenesis of PAH. For monitoring PAH, a high performance liquid chromatography-electrospray ionization-tandem mass spectrometry (HPLC-ESI-MS/MS) method was developed to measure the concentration of UA from rat models and pulmonary arterial endothelial cells (PAECs) models, which were induced by monocrotaline (MCT) and hypoxia, respectively. In addition, the treatment groups were treated by N-acetyl-l-cysteine (NAC), a ROS scavenger. With the confirmation from hematoxylin-eosin (H&E) staining, the HPLC-ESI-MS/MS method was adopted to successfully analyze the concentration of UA. In this study, for the first time, thymine was used as an internal standard (I.S.) of uric acid. The results showed that the UA concentration in the PAH groups was higher than that in the normal groups, while the UA concentration in the treatment groups decreased compared to that in the PAH group (p < 0.05). It was experimentally proven that the HPLC-ESI-MS/MS method is a rapid, efficient and reliable quantitative method to detect PAH. Furthermore, our results indicated that UA and ROS have a double-regulator role.

Thymine firstly was used as an internal standard for uric acid.     

Physiologically based pharmacokinetics model predicts the lack of inhibition by repaglinide on the metabolism of pioglitazone

Purpose: Repaglinide and pioglitazone are both CYP2C8 and CYP3A4 substrates. This study was to determine whether repaglinide has an inhibitory effect on the metabolism of pioglitazone in vitro, in silico and in vivo. Method: In vitro, the effect of repaglinide on the metabolism of pioglitazone was assessed in pooled human liver microsomes. In silico, an IVIVE‐PBPK linked model was built with Simcyp®. Then, a randomized, 2‐phase cross‐over clinical study was conducted in 12 healthy volunteers. Results: Repaglinide showed a strong inhibitory effect on the metabolism of pioglitazone in vitro (K_i = 0.0757 µm ), [I]/K_i > 0.1. The Simcyp® prediction ratios of AUC and C_max between the two treatment groups were both about 1.01. The pharmacokinetics of pioglitazone in clinical trials showed no significant difference between these two treatment groups (p > 0.05). Conclusion: Repaglinide has no significant inhibitory effect on the metabolism of pioglitazone in vivo, which is inconsistent with the in vitro results. The lack of an inhibitory effect was partly due to extensive plasma protein binding and to the high in vivo clearance of repaglinide, for the concentration of repaglinide in vivo was far smaller than in vitro. Copyright © 2015 John Wiley & Sons, Ltd.     

Increased brain uptake of venlafaxine loaded solid lipid nanoparticles by overcoming the efflux function and expression of P-gp

Venlafaxine (VLX) could be pumped out of the brain by P-glycoprotein (P-gp). Moreover, the expression of P-gp distributed in blood–brain barrier could be significantly induced by VLX. Thus, P-gp could be considered as the nature barrier for delivering of VLX to the brain. The aim of this study was to investigate whether the efflux function and increased expression of P-gp could be reversed by utilizing solid lipid nanoparticles (SLN). VLX solid lipid nanoparticles (VLX ? SLN) were prepared and evaluated. Pharmacokinetics and brain distribution of VLX in different formulations were conducted after oral or intravenous administration. P-gp efflux function to VLX was evaluated by the brain uptake amount of VLX, while P-gp expression was investigated by Western blotting. Results indicated that the entrapment, mean size and zata potential of VLX ? SLN was 74.9 ± 3.0 %, 186.3 ± 69.26 nm and ?22.8 ± 7.78 mv, respectively. After vein injection of VLX formulations, the brain uptake amount of VLX from VLX ? SLN was significantly higher than that of VLX solution, VLX solution with empty SLN (VLX+ empty SLN) and VLX solution with Verapamil (VLX + Ver), respectively. Furthermore, the protein mass of P-gp in VLX ? SLN treated group was the lowest among all the investigated groups. These results indicated that SLN could overcome P-gp and achieve brain target by intravenous administration.     

肌肽对局灶性脑缺血大鼠bcl-2、bax表达的影响

目的研究肌肽对局灶性脑缺血大鼠缺血皮质区B淋巴细胞瘤/白血病-2(bcl-2)、bcl-2相关蛋白X(bax)表达的影响。方法 30只SPF级雄性SD大鼠随机分为假手术组、模型组和肌肽组,每组10只。模型组和肌肽组以线栓法制作大鼠永久性脑缺血模型,肌肽组于造模后予肌肽水溶液灌胃[1 000 mg/(kg·d)],其余2组予等量生理盐水灌胃。分别于造模后清醒时、24 h、72 h通过神经功能缺损评分观察神经功能,于72 h采用2,3,5-三苯基氯化四氮唑(TTC)染色观察脑梗死体积、HE染色观察病理形态学改变,并用免疫组化法检测bcl-2和bax表达。结果肌肽组神经功能评分72 h较模型组降低(P<0.05);脑组织缺血损伤病理学改变轻于模型组;脑梗死体积72 h较模型组减小(P<0.01);脑缺血后72 h与假手术组相比,模型组bcl-2表达下降、bax表达上升、bcl-2/bax比值下降(均P<0.05);经肌肽处理后bcl-2表达上升、bax表达下降,bcl-2/bax比值上升(P<0.01或P<0.05)。结论肌肽处理能提高bcl-2表达、降低bax表达及提高bcl-2/bax比值,这可能是肌肽发挥神经保护作用的分子机制之一。     

HPLC法测定左卡尼汀注射液的含量及有关物质

目的:建立简便快捷的左卡尼汀注射液含量及有关物质测定方法。方法:采用AlltechBrava Amino色谱柱(250 mm×4.6 mm,5μm),柱温40℃,以0.01 mol·L-1磷酸盐缓冲液-乙腈(25∶75)为流动相,流速1.0 m L·min-1,检测波长205 nm。结果:左卡尼汀与各有关物质及降解产物色谱峰分离度良好,各杂质峰互不干扰。左卡尼汀、杂质A、杂质B、杂质C、杂质D质量浓度分别在436.2~2 617、3.5~87.4、2.8~56、1.79~44.8、2.54~50.8μg·m L-1范围内线性关系良好,平均回收率(n=9)分别为100.0%、100.1%、101.6%、95.7%和102.5%,其定量限(S/N=10)分别为167.50、4.20、22.40、60.48和30.48 ng。结论:方法学验证结果表明,本法可用于左卡尼汀注射液的质量控制。     

The relationship between Cd‐induced autophagy and lysosomal activation in WRL‐68 cells

This study shows that Cd induces autophagy in the human's embryonic normal liver cell line (WRL‐68). The expression of LC3B‐II and the mature cathepsin L were analyzed by Western blotting. The autophagosomes and lysosomes were directly visualized by electron microscopy and confocal microscopy analysis in Cd‐exposed WRL‐68 cells. In this study, we first found that autophagy induced the activation of lysosomal function in WRL‐68 cells. The lysosomal activation was markedly decreased when the cells were co‐treated with 3‐MA (an inhibitor of autophagy). Secondly, we provided the evidence that the activation of lysosomal function depended on autophagosome–lysosome fusion. The colocalization of lysosome‐associated membrane protein‐2 (LAMP2) and GFP‐LC3 was significantly reduced, when they were treated with thapsigargin (an inhibitor of autophagosome–lysosome fusion). We demonstrated that deletion or blockage of the autophagosome–lysosome fusion process effectively diminished lysosomal activation, which suggests that lysosomal activation occurring in the course of autophagy is dependent on autophagosome–lysosome fusion. Thirdly, we provided evidence that the activation of lysosomal function was associated with lysosomal acid. We investigated the relationship between autophagosome–lysosome fusion and pH in acidic compartments by visualizing fusion process in WRL‐68 cells. This suggests that increasing pH in acidic compartments in WRL‐68 cells inhibits the autophagosome–lysosome fusion. Finally, we found that the activation of lysosomal function was associated with Ca²⁺ stores and the intracellular Ca²⁺ channels or pumps were possibly pH‐dependent. Copyright © 2015 John Wiley & Sons, Ltd.     

(Ba,Sr)TiO3:RE perovskite phosphors (RE = Dy,Eu): nitrate pyrolysis synthesis,enhanced photoluminescence,and reversible emission against heating

A series of (Ba,Sr)TiO₃ phosphors singly doped with Eu³⁺ and Dy³⁺ were successfully synthesized using the nitrate pyrolysis method at 750 °C. Eu³⁺ or Dy³⁺ single-doped BaTiO₃ retained the tetragonal crystal structure of the host, while the Sr²⁺-substituted (Ba,Sr)TiO₃:RE³⁺ (RE³⁺ = Eu³⁺ or Dy³⁺) experienced a phase transformation from tetragonal to cubic phase with a unit cell shrinkage. For Eu³⁺ doped phosphors, BaTiO₃:xEu³⁺ (x = 0.02–0.10) exhibited red photoluminescence and the highest intensity of emission belonged to the optimal-doped BaTiO₃:xEu³⁺ (x = 8 mol%). Moreover, the substitution of 30 mol% Sr²⁺ for Ba²⁺ (that is Ba_0.7Sr_0.3TiO₃:xEu³⁺, x = 8 mol%) further enhanced the emission intensity of BaTiO₃:xEu³⁺ (x = 8 mol%). For Dy³⁺ doped phosphors, BaTiO₃:xDy³⁺ (x = 0.02–0.10) showed yellow photoluminescence and the highest light intensity was from the optimal-doped BaTiO₃:xDy³⁺ (x = 4 mol%). In addition, the substitution of 20 mol% Sr²⁺ for Ba²⁺ (the phosphor Ba_0.8Sr_0.2TiO₃:xDy³⁺, x = 4 mol%) induced further increase in emission intensity of BaTiO₃:xDy³⁺ (x = 4 mol%). The emission intensities at higher temperature of 100 °C retained about 70% and 90% of the initial values at room temperature (RT) for the optimal BaTiO₃:xEu³⁺ (x = 8 mol%) and BaTiO₃:xDy³⁺ (x = 4 mol%) phosphors, respectively, while the emission intensities at the temperature of 100 °C retained about 60% and 80% of the initial intensities at RT for the optimal Sr²⁺-substituted Ba_0.7Sr_0.3TiO₃:xEu³⁺ (x = 8 mol%) and Ba_0.8Sr_0.2TiO₃:xDy³⁺ (x = 4 mol%) phosphors, respectively. It is worth noting that on cooling down to RT again from 210 °C, the BaTiO₃:xDy³⁺ (x = 4 mol%) phosphor exhibited excellent luminescent thermal stability (with a high activation energy of 0.387 eV) and the strongest recovery (∼95%) of PL emission among the series of phosphors. The as-prepared phosphors with optimal compositions would be good candidates for the applications in lighting, display, and related fields.

Eu³⁺ and Dy³⁺ doped (Ba,Sr)TiO₃ red and yellow phosphors were synthesized respectively. Substituting of Sr²⁺ for Ba²⁺ further enhance emission. BaTiO₃:0.04Dy³⁺ possess an excellent thermal stability and the strongest emission recovery of 95% among the phosphors.