Strong electron coupling of FeP4/Ni2P to boost highly-efficient electrochemical nitrate reduction to ammonia.

Electrochemical reduction of contaminated nitrate to ammonia (NRA) opens a new window for mass production of ammonia and the alleviation of energy crises and environmental pollution. However, fabricating effective catalysts for the NRA still faces significant challenges. Herein, a highly-efficient NRA catalyst, FeP4/Ni2P, was successfully constructed. The strong electron coupling at heterointerfaces of FeP4/Ni2P promoted the generation of abundant active hydrogen *H, inhibited the competition of the HER, accelerated the hydrogenation of the NRA. Benefiting from these, the catalyst displays good NRA catalytic activity in the neutral electrolyte, with the NH3 FE of 97.83 ± 0.091 %, NH3 selectivity of 98.67 ± 0.50 %, NH3 yield rate of 0.262 ± 0.01 mmol·h-1·cm-2, and NO3- conversion rate of 93.02 ± 0.14 %. The DFT theoretical calculations demonstrated that the FeP4/Ni2P heterointerfaces played a critical role in shearing the H-OH bonds of water, resulting in generating more active hydrogen as a key NRA hydrogenation source, and hindering the *H dimerization to form H2, enhancing the NH3 selectivity. This work has a certain reference value for designing excellent catalysts for the NRA.

Thymic self-antigen expression for immune tolerance and surveillance.

T cells are a group of lymphocytes that play a central role in the immune system, notably, eliminating pathogens and attacking cancer while being tolerant of the self. Elucidating how immune tolerance is ensured has become a significant research issue for understanding the pathogenesis of autoimmune diseases as well as cancer immunity. T cell immune tolerance is established mainly in the thymic medulla by the removal of self-responsive T cells and the generation of regulatory T cells, this process depends mainly on the expression of a variety of tissue restricted antigens (TRAs) by medullary thymic epithelial cells (mTECs). The expression of TRAs is known to be regulated by at least two independent factors, Fezf2 and Aire, which play non-redundant and complementary roles by different mechanisms. In this review, we introduce the molecular logic of thymic self-antigen expression that underlies T cell selection for the prevention of autoimmunity and the establishment of immune surveillance.

Overexpression of the immediate early response 5 gene increases the radiosensitivity of HeLa cells.

The effects of the immediate early response 5 (IER5) gene on the sensitivity of HeLa cells to radiation remain unclear. In the present study, stably transfected HeLa cells resulting in the knockdown or overexpression of IER5 were investigated. In addition, xenografts of normal, IER5-silenced and -overexpressed HeLa cells were injected into nude mice and examined. The results demonstrated that the radiosensitivity of the IER5-overexpressed HeLa cells was significantly increased compared with that of the normal and IER5-silenced cells. The upregulation of IER5 effectively decreased cell proliferation and IER5 silencing promoted cell proliferation compared with that in the normal HeLa cells. Following irradiation of the cells with IER5 knockdown, cell cycle was arrested at the G2/M phase and an increase in the proportion of S phase cells was observed. By contrast, the overexpression of IER5 led to an increase in the proportion of G1 phase cells. Furthermore, the upregulation of IER5 inhibited tumor growth in vivo. The present findings demonstrate that the IER5 gene affects the radiosensitivity of HeLa cells and serves an important role in cell proliferation, suggesting that this gene may be a potential radiotherapeutic target in cervical cancer.

Connexin43 Modulates X-Ray-Induced Pyroptosis in Human Umbilical Vein Endothelial Cells.

OBJECTIVE: Pyroptosis is an inflammatory form of programmed cell death. This phenomenon has been recently reported to play an important role in radiation-induced normal tissue injury. Connexin43 (Cx43) is a gap junction protein that regulates cell growth and apoptosis. In this study, we investigated the effect of Cx43 on X-ray-induced pyroptosis in the human umbilical vein endothelial cells (HUVECs). METHODS: HUVECs, Cx43 overexpression, and Cx43 knockdown strains were irradiated with 10 Gy. Proteins were detected using western blot analysis. Cell pyroptosis was evaluated using the fluorescence-labeled inhibitor of caspase assay (FLICA) and propidium iodide staining through flow cytometry and confocal microscopy. Cell morphology and cytotoxicity were detected by scanning electron microscopy and lactate dehydrogenase release assay, respectively. RESULTS: Irradiation with 10 Gy X-ray induced pyroptosis in the HUVECs and reduced Cx43 expression. The pyroptosis in the HUVECs was significantly attenuated by overexpression of Cx43 as it decreased the level of active caspase-1. However, interference of Cx43 expression with siRNA significantly promoted pyroptosis by increasing the active caspase-1 level. Pannexin1 (Panx1), a gap junction protein regulates pyroptosis, and its cleaved form is used to evaluate channel opening and active state. The level of cleaved Panx1 in the HUVECs and Cx43 knockdown strains increased in the presence of X-ray, but decreased in the Cx43 overexpression strains. Furthermore, interference of Panx1 with siRNA alleviated the upregulation of pyroptosis caused by Cx43 knockdown. CONCLUSION: Results suggest that single high-dose X-ray irradiation induces pyroptosis in the HUVECs. In addition, Cx43 regulates pyroptosis directly by activating caspase-1 or indirectly by cleaving Panx1.

Pharmacokinetics of Sijunzi decoction in rat plasma after oral administration using ultra-high-performance liquid chromatography electrospray ionization quadrupole-time of flight mass spectrometry.

Sijunzi decoction (SJZD) is one of the most well-known traditional Chinese herbal formulations. This study elucidates the pharmacokinetics of SJZD in rat plasma after the administration of a single oral dose of 3 mL/kg using ultra-high-performance liquid chromatography electrospray ionization quadrupole-time of flight mass spectrometry (UHPLC-ESI-Q-TOF/MS) with bergapten as an internal standard. The separation was performed on an Agilent Zorbax Eclipse Plus C18 column (2.1 × 50 mm, 1.8 µm) by elution with acetonitrile and water (containing 0.1% formic acid) at a flow rate of 0.3 mL/min. Electrospray ionization in positive and negative ion modes was used to quantify six compounds, with monitored ion m/z values of 249.1397 [M + H]+ and 529.3857 [M + H]+ for atractylenolide III (ATL-III) and pachymic acid (PA), respectively, and m/z of 1107.6638 [M - H]- , 991.5746 [M - H + HCOO]- , 821.3714 [M - H]- , 469.3315 [M - H]- for ginsenoside Rb1, Re, glycyrrhizic acid (GL), and glycyrrhetinic acid (GA), respectively. The calibration curves for ginsenoside Rb1 , Re, ATL-III, PA, GL and GA were 0.0015-0.75, 0.001-0.5, 0.0004-0.2, 0.003-0.9, 0.0015-0.3 and 0.001-1.5 µg/mL, respectively. The intra- and inter-day precisions (RSD) were <14.3%. The rapid, sensitive and specific UHPLC-ESI-Q-TOF/MS method developed and validated in this study was successfully applied to the simultaneous determination of the six components of SJZD using rat plasma for pharmacokinetic studies after oral administration.

Ferulic Acid Mitigates Radiation Injury in Human Umbilical Vein Endothelial Cells In Vitro via the Thrombomodulin Pathway.

Cell death and tissue injury occur as a result of radiation accidents and radiotherapy. The role of endothelial cell damage in mediating radiation-induced acute tissue injury has been extensively studied. We previously demonstrated that ferulic acid (FA) mitigates radiation-induced hematopoietic injury in mice and lessens radiation-induced oxidative damage in human umbilical vein endothelial cells (HUVECs). The purpose of the current study was to determine whether FA can protect HUVECs from radiation toxicity in a cell model via the thrombomodulin (Thbd) pathway, an anti-radiation pathway with anticoagulant, anti-inflammatory and antioxidant properties. HUVEC culture media was supplemented with FA 12 h before 4 Gy 60Co gamma irradiation. At 30 min postirradiation, the FA media was refreshed, then renewed once daily. HUVEC injury was assessed at day 5 postirradiation through cell proliferation analysis. Ferulic acid significantly ameliorated HUVEC radiation injury, as evidenced by increases in cell viability and angiogenesis and decreases in G2/M cell cycle arrest and levels of high mobility group box 1 protein (HMGB1), interleukin (IL)-6 and IL-8. These findings can be attributed to the effect of FA on the Thbd promoter, resulting in increased expression of Thbd and activated protein C with associated radioprotection. These observations indicate that FA intervention significantly ameliorates HUVEC radiation injury via the Thbd pathway. Therefore, FA could be further developed as a potential agent to mitigate radiation-induced damage.

[Pilot study of PTEN deletion affecting the expression of Cu/Zn SOD].

OBJECTIVE: To investigate whether the deletion of PTEN affects the expression of Cu/Zn SOD and the related biology. METHODS: Protein and mRNA expression levels of PTEN, P-Akt, Cu/Zn SOD in the control immortalized wild type mouse embryonic fibroblast cells (PTEN+/+) and PTEN-null cells (PTEN-/-) were evaluated by Western blot and Northern blot respectively. The level of superoxide anions were detected using fluorescent probes. The DNA damage was documented by single cell alkalescence gel assay. MTT was used to study the effect of H2O2 on the proliferation of cells. RESULTS: The expression of Cu/Zn SOD was down regulated at both protein and mRNA levels, and the level of superoxide anions increased in the PTEN-null cells (PTEN-/-). The phosphorylation level of Akt kinase was up-regulated and the antiproliferative effect of H2O2 decreased in PTEN-/- cells. Furthermore, DNA damage was observed significantly severer in both the blank control and H2O2 treated groups than that in the PTEN+/+ cells. CONCLUSIONS: Deletion of PTEN affects the expression of Cu/Zn SOD. As a result, reactive oxygen species (ROS) keep at a high level, along with decrease of accumulated oxidative damage and the antiproliferative effect of ROS.

PTEN deletion leads to deregulation of antioxidants and increased oxidative damage in mouse embryonic fibroblasts.

Despite the significance of oxidative damage in carcinogenesis, the molecular mechanisms that lead to increased susceptibility to oxidative stress are not well understood. We now report a link between loss of protection against oxidative damage and loss of function of PTEN, a highly mutated tumor suppressor gene in a variety of human tumors. Using two-dimensional gel electrophoresis, combined with Western and Northern blot analyses, we found that PTEN deficiency in mouse embryonic fibroblasts (MEFs) displays deregulated expression of several antioxidant enzymes, including peroxiredoxins 1, 2, 5, and 6 and Cu, Zn superoxide dismutase. In these Pten-deleted MEFs, the basal levels of reactive oxygen species (ROS) were increased, and both the basal level and the ROS-induced oxidative damage of DNA were increased, as evidenced by increased levels of hydrogen peroxide (H2O2), superoxide anion, 8-hydroxy-2'-deoxyguanosine, and DNA double-strand breaks. We further show that Pten deletion is correlated with resistance to H2O2-induced expression of several antioxidants. These findings suggest an essential role for PTEN in maintaining the normal redox state of mouse embryonic fibroblasts against oxidative damage. They also provide a molecular link between PTEN, whose inactivation is known to be involved in a variety of human tumors, and antioxidants, whose perturbation leads to oxidative damage of cells.