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1.
Artigo em Inglês | MEDLINE | ID: mdl-32052339

RESUMO

The widespread use of zinc oxide nanoparticles (ZnO NPs), the second most produced nanomaterial, inevitably leads to their release into the environment. In this study, dissolution and transformation of ZnO NPs in the presence of δ-MnO2, an abundant and ubiquitous manganese (Mn) oxide mineral, was investigated via a suite of techniques covering bulk to molecular scales. Dissolution kinetics indicated that the presence of δ-MnO2 significantly affected ZnO NP dissolution rate/trend and equilibrium Zn2+ concentration, which were found to be mainly dependent on the concentration and mass ratio of ZnO NPs and δ-MnO2. Approximately 300 mg ZnO NPs per g δ-MnO2 was expected for ZnO NP uptake at pH 7.0 via ZnO NP dissolution and surface Zn2+ adsorption. X-ray diffraction (XRD), ζ potential, high-resolution transmission electron microscopy (HR-TEM), and Zn K-edge X-ray absorption spectroscopy (XAS) results revealed that when the mole content of ZnO NPs was less than the total adsorption sites of δ-MnO2 surface, ZnO NPs were completely dissolved and adsorbed on δ-MnO2 surface in the form of inner-sphere complexes. A fraction of ZnO NPs persisted when the mole ratio of ZnO to δ-MnO2 further increased. These results suggest that the transformation and fate of ZnO NPs is affected by environment-relevant minerals such as Mn oxides due to their huge capacity of fixing dissolved metal cations at the surface or interlayer structure.

2.
Environ Pollut ; 260: 114046, 2020 Jan 25.
Artigo em Inglês | MEDLINE | ID: mdl-32014747

RESUMO

Hexavalent chromium has aroused a series of environmental concerns due to its high mobility and toxicity. Iron and manganese oxides usually coexist in the environments and influence the speciation and geochemical cycling of chromium. However, the interaction mechanism of iron-manganese oxides with dissolved Cr(VI) remains largely unknown. In this work, the interaction processes of dissolved Cr(VI) and manganite in the presence of goethite coating were investigated, and the effects of pH (2.0-9.0) and iron oxide content were also studied. Manganite-goethite composites were formed with uniform micromorphologies in the system of manganite and Fe(II). In the reaction system of single manganite and Cr(VI), manganite could only adsorb but not reduce Cr(VI), with the adsorption amount decreasing at higher pHs. In the reaction system of manganite-goethite composites and Cr(VI), adsorbed Cr(VI) was reduced to Cr(III) by Fe(II) on composites surface. The generated Cr(III) was then retained as Cr(OH)3 on the mineral surface. Goethite coating suppressed the re-oxidation of newly formed Cr(III) by manganite. The amounts of adsorbed Cr(VI) and generated Cr(III) increased with increasing iron oxide content, and increased first and then decreased with increasing pH. The Cr(III) formation and Cr(VI) adsorption amount reached the maximum at pH 5.0-6.0. The present work highlights the transformation and retention of Cr(VI) by iron-manganese oxides and provides potential implications for the use of such oxides in the remediation of Cr(VI) polluted waters and soils.

3.
J Hazard Mater ; 390: 122166, 2020 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-32004764

RESUMO

The speciation, toxicity and mobility of chromium (Cr) are significantly affected by natural iron-manganese nodules due to the adsorption and redox reactions in soils. However, the redox processes in oxic environments have received little attention. In this work, the interaction mechanism between Cr(III) and natural iron-manganese nodules was studied under oxic conditions, and the effects of chemical composition, dissolved oxygen concentration, pH, ionic strength and coexisting ions were further investigated. The results showed that iron-manganese nodules could effectively oxidize dissolved Cr(III), and most of the newly formed Cr(VI) was adsorbed on the surface of nodules. In iron-manganese nodules, manganese oxides mainly contributed to Cr(III) oxidation, and iron oxides facilitated the adsorption and immobilization of Cr(VI). In addition, Cr(III) could be catalytically oxidized to Cr(VI) on the surface of manganese oxides through the generation of Mn(III) intermediate or Mn(IV) oxides from released Mn(II) under oxic conditions. The oxidation rate of Cr(III) by the nodules decreased with increasing pH from 2.0 to 8.0, and increased with increasing ionic strength. This work reveals the adsorption and catalytic oxidation mechanism of Cr(III) by iron-manganese nodules in a simulated open system, and improves the understanding of the geochemical behavior of chromium in soils.

4.
J Hazard Mater ; 390: 122165, 2020 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-32006848

RESUMO

Fe-Mn nodules are widely distributed and regarded as excellent adsorbents for heavy metals. Their adsorption-desorption reactions with heavy metal ions are usually accompanied by redox processes. Herein, Fe-Mn nodules were used as adsorbents for Cd(II) and As(III,V) at a constant cell voltage under electrochemically controlled reduction and oxidation, respectively. The results showed that the adsorption performance for Cd(II) and As(III,V) was enhanced respectively due to the decrease and increase of Mn average oxidation state (Mn AOS) in Fe-Mn nodules. High birnessite content and Mn average oxidation state (Mn AOS) improved the adsorption of Cd(II) and As(III,V). The adsorption capacity for Cd(II) and total As increased with increasing voltage. With increasing pH, the adsorption capacity for Cd(II) increased first and then reached equilibrium, and that of total As decreased and then increased. The Cd(II) electrochemical adsorption capacity (129.9 mg g-1) and the removal efficiency for total As at 1.2 V (83.6 %) in As-containing wastewater at an initial concentration of 4.068 mg L-1 were remarkably higher than the corresponding inorganic adsorption performance (9.46 mg g-1 and 70.5 %, respectively). This work may further promote the application of natural Fe-Mn nodules in the adsorption of heavy metals from wastewaters.

5.
Chemosphere ; 247: 125822, 2020 Jan 06.
Artigo em Inglês | MEDLINE | ID: mdl-31927232

RESUMO

Manganese oxides are potentially used for the electrochemical removal of heavy metals from wastewater. However, little is known about the performance and mechanism of simultaneous electrosorption for multiple heavy metals, especially for coexisting anions and cations. In this work, birnessite-type manganese oxide was used for the electrochemical adsorption of coexisting Cd(II) cations and As(V) anions with a symmetrical electrode system, and the effects of the concentrations of coexisting metal ions and applied voltage were investigated. The results indicated that both the Cd(II) and As(V) adsorption capacity of birnessite increased in a mixed solution containing Cd(II) cations and As(V) anions, compared with that in single heavy metal solution. This synergistic effect was mainly ascribed to the formation of manganese arsenate precipitate and the reduction dissolution of birnessite on the cathode and the re-oxidation of Mn(II) with subsequently increased fresh adsorption sites on the anode. The electrochemical adsorption capacity for As(V) increased from 52.7 to 88.0 and 496.0 mmol kg-1 with increasing Cd(II) concentration from 0.1 to 1.5 mM, respectively, in the mixed solution containing 0.5 mM As(V). The removal efficiency of heavy metals increased first and then decreased with increasing voltage from 0 to 1.2 V. Under the optimum condition at 0.6 V for 12 h, the electrochemical adsorption capacity increased with increasing Cd(II) and As(V) concentrations and the highest capacity reached 2132.0 mmol kg-1 for Cd(II) and 1996.0 mmol kg-1 for As(V). This work provides a facile technique for the treatment of wastewaters containing metal anions and cations.

6.
Artigo em Inglês | MEDLINE | ID: mdl-31997248

RESUMO

Proton adsorption behavior on the surface of Al-substituted goethites as a function of pH and ionic strength was investigated and simulated with the multisite surface complexation (MUSIC) model. In addition, X-ray diffraction, X-ray photoelectron spectroscopy, and field emission scanning electron microscope were used to characterize the crystal structure, chemical composition, micromorphology, and surface properties of the Al-substituted goethite. Al substitution was found to affect the crystal structure and micromorphology of goethite. The morphological differences did not result in significant differences in PZC value but largely affected the surface charge values. Goethite surface charge capacity increased progressively with increasing amount of Al substitution, which was attributed to increases in the density of surface coordinated sites due to the increase in (021)/(110) face ratio. The optimization calculations enabled a satisfactory fitting of the titration data of both pure goethite and Al-substituted goethite, and the MUSIC model facilitated a more specific understanding of the charging behavior of Al-substituted goethite. The singly (≡FeOH-0.5 + ≡AlOH-0.5) and triply coordinated (≡Fe3O-0.5 + ≡AlFe2O-0.5) surface groups were most likely responsible for the basic charging behavior of goethite in the pH range of 4-10. All results indicate that the MUSIC model has excellent performance in characterizing Al-substituted goethite, and the model has promising application prospect in other substituted metal (hydr)oxides.

7.
Sci Total Environ ; 703: 135678, 2020 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-31771850

RESUMO

Arsenite (As(III)) is generally removed by adsorption or coprecipitation after being oxidized to arsenate (As(V)). Electrocoagulation is regarded as an effective and environment-friendly method for arsenic (As) removal from wastewater. However, some disadvantages including the passivation of electrode and high energy consumption limit its wide application. Herein, a multi-cycle galvanostatic charge-discharge technique was employed to remove aqueous As(III) using hematite prepared through a microwave-assisted hydrothermal reaction. When charge-discharge experiments were conducted at the potential window of -0.8-0 V (vs. SCE) in As(III) solution with NaCl as the background electrolyte, ClO- intermediates and the counter electrode at high potential contributed much to As(III) oxidation. As(V) was adsorbed on ferrihydrite generated from the re-oxidation of released Fe2+, forming FeAsO4 precipitate. A higher removal ratio of As(T) was achieved at initial pH 7.0 compared with that at initial pH 5.0 and 9.0. When the hematite mass was 4, 10 and 15 mg, the removal ratio of As(T) reached 55.2%, 79.6% and 98.6% after 600 cycles of charge-discharge. The periodic redox reactions of hematite electrodes occurred in each charge-discharge process, effectively avoiding the passivation of electrode. Additionally, the electrochemical system can be used as a supercapacitor for power output. The present work provides a novel strategy for high-efficiency As(III) immobilization and removal from aqueous solution.

8.
Environ Pollut ; 256: 113462, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31706772

RESUMO

Natural birnessite-like minerals are commonly enriched in various transitional metals (TMs), which greatly modify the mineral structure and properties. However few studies are yet conducted systematically on the effects of TM doping on birnessite reactivity towards Cr(III) oxidation. In the present study, the transformation behaviors of Cr(III) on Co-, Ni-, V-containing birnessites were investigated. Co and Ni doping generally decrease the mineral crystalline sizes and hydrodynamic sizes (DH) while V-doping greatly decreases the crystalline sizes but not the DH, owing to particle aggregation. Co and Ni firstly decrease and then increase the mineral zeta potentials (ζ) at pH4 while V decreases ζ. Electrochemical specific capacitances for Co-containing birnessites are gradually reduced, while those for Ni-doped birnessites are slightly reduced and for V-doped birnessites increased, which have a positively linear relationship with the amounts of Cr(III) oxidized by these samples. Cr(III) removal efficiencies from solution by these Co-, Ni- and V-containing birnessites are 26-51%, ∼62-72% and ∼96-100%, respectively, compared to ∼92% by pure birnessite. Cr(III) oxidation kinetics analysis demonstrates the gradual decrease of Mn(IV) and concurrent increase of Mn(III) and the adsorption of mainly Cr(III) on mineral surfaces. A negatively linear relationship exists between birnessite lateral sizes and the proportions of Mn(IV/III) consumed to oxidize Cr(III). Apparent initial Cr(III) oxidation rate (kobs) for Co-containing birnessites are greatly reduced, while those for Ni-doped samples moderately decreased and for V-doped samples first increased and then decreased. A positively or negatively linear relationship exists between kobs or the amount of Mn(II) released and the mineral Mn(IV) content respectively. Cr(III) oxidation probably initiates from layer edge sites of Ni-doped birnessites but the vacancies of Co- and V-containing birnessites. These results provide insights into the reaction mechanisms of Cr(III) with natural birnessite-like minerals.

9.
J Exp Med ; 217(1)2020 Jan 06.
Artigo em Inglês | MEDLINE | ID: mdl-31636135

RESUMO

Follicular helper T (Tfh) cells provide essential help for humoral immune response. Transcriptional factor Bcl6 is the master regulator for Tfh generation and is induced very early after T cell activation in a CD28-dependent manner, but how CD28 signal promotes Bcl6 early expression remains unknown. Here we found that CD28 signal quickly induces expression of the H3K36me2 methytransferase Nsd2, which is required for Bcl6 expression as early as the first cell division after T cell activation. Nsd2 deficiency in T cells leads to decreased Bcl6 expression, impaired Tfh generation, compromised germinal center response, and delayed virus clearance. Ectopic Bcl6 expression rescues the Tfh defect of Nsd2 KO cells. ICOS signal is dispensable for early Nsd2 induction but required for sustained Nsd2 expression, which is critical for Tfh maintenance. Overexpression of Nsd2 increases Bcl6 expression and enhances Tfh generation; 4-mo-old mice even develop spontaneous Tfh. Overall, our study reveals Nsd2 as a critical epigenetic regulator for Tfh differentiation.

10.
Artigo em Inglês | MEDLINE | ID: mdl-31350057

RESUMO

OBJECTIVE: To evaluate the efficacy and safety of leflunomide (LEF) as induction treatment in a series of Takayasu arteritis (TA) patients based on a Chinese cohort. METHOD: Fifty-six patients from the East China TA cohort treated with LEF for at least 3 months were enrolled in this study, including the naïve LEF treatment patients (n = 41) and the cyclophosphamide (CYC)-resistant LEF treatment patients (n = 15). Data in clinical features, NIH score and angiography were collected. Response to treatment was assessed by rates of complete remission (CR) and partial remission (PR) and response rate (RR) after 6 and 12 months of treatment. RESULTS: The total CR rate and RR were 67.86% and 83.93% after 6 months, and 55.36% and 69.64% after 12 months, respectively. ESR and CRP levels and NIH scores decreased significantly after 12 months of LEF treatment (P < 0.05). Patients of CYC-resistant switched to LEF and reached the CR of 60.00% (9/15) and RR of 86.67% (13/15) after 6 months, and 73.33% (11/15) and 80.00% (12/15) after 12 months, respectively, with decrease in NIH scores (all P < 0.05). After following up for 14.44 ± 6.86 months, 48 patients (85.71%) continued LEF treatment with good tolerance. One patient died from progression of TA after 2 months, 2 patients relapsed, and 3 patients with side effects were switched to other immunosuppressive agents. CONCLUSIONS: LEF led to a quick induction and sustained remission of TA, especially in refractory cases, and therefore, should be considered as an alternative treatment for TA.

11.
Environ Sci Technol ; 53(15): 8854-8861, 2019 Aug 06.
Artigo em Inglês | MEDLINE | ID: mdl-31313923

RESUMO

Ferrihydrite commonly occurs in soils and sediments, especially in acid mine drainage (AMD). Solar irradiation may affect Fe(II)-catalyzed transformation of metastable ferrihydrite to more stable iron oxides on AMD surface. We investigated the Fe(II)-catalyzed transformation process and mechanism of ferrihydrite under light irradiation. In nitrogen atmosphere, Fe2+aq could be oxidized to goethite and lepidocrocite by hydroxyl radical (OH•), superoxide radical (O2•-) and hole (hvb+) generated from ferrihydrite under ultraviolet (UV) irradiation (300-400 nm) at pH 6.0, and O2•- and hvb+ were mainly responsible for Fe2+aq oxidation. In addition, the ligand-to-metal charge-transfer (LMCT) process between Fe(II) and ferrihydrite could be promoted by UV irradiation. Goethite proportion increased with increasing Fe2+aq concentration. Both visible (vis) and solar irradiation could also lead to the oxidation of Fe2+aq to goethite and lepidocrocite, and the proportion of lepidocrocite increased with increasing light intensity. Fe2+aq was photochemically oxidized to schwertmannite at pH 3.0 and 4.5, and the oxidation rate was higher than that under dark conditions in air. The photochemical oxidation rate of Fe2+aq decreased in the presence of humic acid. This study facilitates a better understanding of the formation and transformation of iron oxides in natural environments and ancient Earth.


Assuntos
Ferro , Energia Solar , Compostos Férricos , Oxirredução , Água
12.
Sci Total Environ ; 684: 694-704, 2019 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-31174097

RESUMO

The interactions between low-molecular weight organic acids (LMWOAs) and selenium (Se) on mineral/water interfaces affect the release, immobilization and bioavailability of Se in nature. Herein, the effects of three environmentally relevant LMWOAs (i.e., oxalic (Oxa), succinic (Suc) and citric (Cit) acids) on Se(IV) adsorption to goethite under oxic conditions were investigated using batch experiments, speciation fractionation, and ATR-FTIR and XPS analyses. The LMWOAs exhibited a competitive-synergistic coupling effect on Se(IV) adsorption to goethite, which inhibited the adsorption rate of Se(IV) by 14.1, 13.3 and 8.0 times. However, immobilization of Se(IV) was simultaneously enhanced by 39.1%, 34.6% and 14.1% in the following order Oxa > Suc > Cit. The results obtained by fractionation of the adsorbed Se(IV) revealed that the enhancement was due to surface binding as well as speciation transformation from ligand-exchangeable Se(IV) into residual fractions, which increased by approximately 18% in the presence of the LMWOAs. The dissolution of goethite significantly improved due to the LMWOAs and decreased to different degrees as the concentration of Se(IV) increased. The monodentate mononuclear complexes (58.2%) and Lewis base sites bonded Se (41.8%) were the predominant surface species of Se(IV) in goethite-Se(IV) system. The ATR-FTIR and high-resolution XPS analyses demonstrated that the formation of ≡FeO(SeO)O-CO surface complexes (22.8-27.0%) occurred in the presence of LMWOAs, which could be closely correlated with the interface-mediated reduction of Se(IV). In addition, the predominant mechanism for the formation of residual Se is LMWOA specific, in which ferric selenite-like precipitation was dominant for Suc (10.6%) and Cit (11.6%) and reduction was dominant for Oxa (17.5%). Overall, LMWOAs play an important role in Se(IV) immobilization and speciation transformation and may facilitate understanding the Se bioavailability in rhizosphere soils under oxic conditions.

13.
Opt Express ; 27(11): 15548-15564, 2019 May 27.
Artigo em Inglês | MEDLINE | ID: mdl-31163750

RESUMO

When applied inside Earth's atmosphere, the star tracker is sensitive to sky background produced by atmospheric scattering and stray light. The shot noise induced by the strong background reduces star detection capability and even makes it completely out of operation. To improve the star detection capability, an attitude-correlated frames adding (ACFA) approach is proposed in this paper. Firstly, the attitude changes of the star tracker are measured by three gyroscope units (GUs). Then the mathematical relationship between the image coordinates at different time and the attitude changes of the star tracker is constructed (namely attitude-correlated transformation, ACT). Using the ACT, the image regions in different frames that correspond to the same star can be extracted and added to the current frame. After attitude-correlated frames adding, the intensity of the star signal increases by n times, while the shot noise increases by n~n/2 times due to its stochastic characteristic. Consequently, the signal-to-noise ratio (SNR) of the star image enhances by a factor of n~2n. Simulations and experimental results indicate that the proposed method can effectively improve the star detection ability. Hence, there are more dim stars detected and used for attitude determination. In addition, the star centroiding error induced by the background noise can also be reduced.

14.
Environ Pollut ; 252(Pt B): 1193-1201, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31252117

RESUMO

Evaluating the fate and transport of nanoparticles (NPs) in the subsurface environment is critical for predicting the potential risks to both of the human health and environmental safety. It is believed that numerous environmental factors conspire to control the transport dynamics of nanoparticles, yet the effects of organic phosphates on nanoparticles transport remain largely unknown. In this work, we quantified the transport process of TiO2 nanoparticle (nTiO2) and their retention patterns in water-saturated sand columns under various myo-inositol hexakisphosphate (IHP) or phosphate (Pi) concentrations (0-180 µM P), ferrihydrite coating fractions (λ, 0-30%), ionic strengths (1-50 mM KCl), and pH values (4-8). The transport of nTiO2 was enhanced at increased P concentration due to the enhanced colloidal stability. As compared with Pi at the equivalent P level, IHP showed stronger effect on the electrokinetic properties of nTiO2 particles due to its relatively more negative charge and higher adsorption affinity, thereby facilitating the nTiO2 transport (and thus reduced retention) in porous media. At the IHP concentration of 5 µM, the retention of nTiO2 increased with increasing λ and ionic strength, while decreased with pH. In addition, the retention profiles of nTiO2 showed a typical hyperexponential pattern for most scenarios mainly due to the unfavorable attachment, and can be well described by a hybrid mathematical model that coupled convection dispersion equations with a two-site kinetic model and DLVO theory. These quantitative estimations revealed the importance of IHP on affecting the transport of nTiO2 typically in phosphorus-enriched environments. It provides new insights into advanced understanding of the co-transport of nanoparticles and phosphorus in natural systems, essential for both nanoparticle exposure and water eutrophication.


Assuntos
Modelos Químicos , Nanopartículas/química , Adsorção , Compostos Férricos , Concentração de Íons de Hidrogênio , Cinética , Modelos Teóricos , Concentração Osmolar , Fosfatos/química , Fósforo , Ácido Fítico , Porosidade , Quartzo , Dióxido de Silício/química , Titânio/química , Água
15.
Front Immunol ; 10: 884, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31068949

RESUMO

Objectives: To determine the relationship between bone marrow edema (BME), synovitis, and bone erosion longitudinally using a collagen induced arthritis mice (CIA) model and to explore the potential pathogenic role of BME in bone erosion. Methods: CIA was induced in DBA/1J mice. BME and corresponding clinical symptoms of arthritis and synovitis during the different time points of CIA development were assayed by magnetic resonance imaging (MRI), arthritis sore, and histologic analyses. The expression of osteoclasts (OCs), OCs-related cytokines, and immune cells in bone marrow were determined by flow cytometry, immunohistochemistry, immunofluorescence staining, and real-time PCR. The OCs formation was estimated using in vitro assays. Results: MRI detected BME could emerge at day 25 in 70% mice after the first immunization (n = 10), when there were not any arthritic symptoms, histological or MRI synovitis. At day 28, BME occurred in 90% mice whereas the arthritic symptom and histological synovitis were only presented in 30 and 20% CIA mice at that time (n = 10). The emergence of BME was associated with an increased bone marrow OCs number and an altered distribution of OCs adherent to subchondral bone surface, which resulted in increased subchondral erosion and decreased trabecular bone number during the CIA process. Obvious marrow environment changes were identified after BME emergence, consisting of multiple OCs related signals, including highly expressed RANKL, increased proinflammatory cytokines and chemokines, and highly activated T cells and monocytes. Conclusions: BME reflects a unique marrow "osteoclastic environment," preceding the arthritic symptoms and synovitis during the development of CIA.

16.
Clin Exp Rheumatol ; 2019 May 22.
Artigo em Inglês | MEDLINE | ID: mdl-31140393

RESUMO

OBJECTIVES: Systemic inflammation is very closely linked to the increased risk of cardiovascular diseases (CVD) in rheumatoid arthritis (RA). We investigated the cardiac changes during the development of arthritis in collagen-induced arthritis (CIA) mice to explore the potential role of inflammation on cardiac dysfunction in RA. METHODS: Arthritis severity was evaluated using clinical indices, micro-computed tomography and histopathology. Cardiac function was determined by transthoracic echocardiography at weeks 5, 7, 9 and 11 after immunisation in mice. At week 7 (day 50), mice joints and hearts were removed for pathological study, and cardiomyocytes and cardiac fibroblasts were isolated using Langendorff perfusion method ex vivo to measure the expression of inflammatory and cardiac-related genes by real time PCR. The expression of key molecule in cardiac dysfunction (ß-MHC) was also tested in H9c2 cardiomyocyte treated with sera derived from CIA mice or RA patients. RESULTS: At day 50 after immunisation, cardiac function in CIA mice was prominently reduced as evidenced by decreased ejection fraction (EF) and fractional shortening (FS), increased left ventricular end-systolic volume (LVESV) and internal systolic diameter (LVIDs). Accordingly, enhanced inflammatory cell infiltration and fibrosis were identified in ventricular tissues pathologically, and increased inflammatory gene expression including TNF-α, IL-6, IL-17 and MMP3 was detected in isolated ventricular cardiomyocytes and cardiac fibroblasts from CIA mice. Furthermore, H9c2 cells treated with sera from CIA mice or RA patients exhibited high levels of ß-MHC. CONCLUSIONS: Joint inflammation is associated with an obvious cardiac dysfunction and enhanced inflammation infiltration and inflammatory cytokine production in cardiomyocytes and cardiac fibroblasts during CIA development. Our data provide the direct evidence that inflammation contributes to the development of cardiac diseases in RA patients.

17.
Oxid Med Cell Longev ; 2019: 2691514, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30992737

RESUMO

Background and Aims: Vascular smooth muscle cells (VSMCs) are central components of atherosclerotic plaque. Loss of VSMCs through apoptotic cell death can cause fibrous cap thinning, necrotic core formation, and calcification that may destabilize plaque. Elevated glucocorticoid levels caused by psychological stress promote VSMC apoptosis and can exacerbate atherosclerosis in mice and humans. Changes in the levels of antiapoptosis microRNA-25 (miR-25) have been linked with heart disease, inflammation, VSMC phenotype, oxidative stress, and apoptosis. Here, we investigated the pathways and mechanisms of glucocorticoid-induced apoptosis of mouse VSMCs and the protective role of miR-25. Methods: Primary mouse VSMCs were cultured +/- corticosterone for 48 h. Apoptosis, ROS, apoptotic protein activities, miR-25, MOAP1, a miR-25 target, and p70S6 kinase were quantified at intervals. The roles of miR-25 were assessed by treating cells with lenti-pre-miR-25 and anti-miR-25. Results: VSMC apoptosis, caspase-3 activity, and Bax were increased by corticosterone, and cell death was paralleled by marked loss of miR-25. Protection was conferred by pre-miR-25 and exacerbated by anti-miR-25. Pre-miR-25 conferred reduced expression of the proapoptotic protein MOAP1, and the protective effects of pre-miR-25 were abrogated by overexpressing MOAP1. The antiapoptotic effects of miR-25 were paralleled by inhibition of the p70S6K pathway, a convergence target for the survival signaling pathways, and protection by pre-miR-25 was abrogated by the p70S6k inhibitor rapamycin. Conclusions: MicroRNA-25 blocks corticosterone-induced VSMC apoptosis by targeting MOAP1 and the p70S6k pathway. Therapeutic manipulation of miR-25 may reduce atherosclerosis and unstable plaque formation associated with chronic stress.


Assuntos
Corticosterona/farmacologia , MicroRNAs/metabolismo , Miócitos de Músculo Liso/efeitos dos fármacos , Miócitos de Músculo Liso/metabolismo , Proteínas Adaptadoras de Transdução de Sinal/biossíntese , Animais , Apoptose/efeitos dos fármacos , Proteínas Reguladoras de Apoptose/biossíntese , Regulação para Baixo/efeitos dos fármacos , Camundongos , Camundongos Endogâmicos C57BL , Miócitos de Músculo Liso/citologia , Estresse Oxidativo/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismo , Proteínas Quinases S6 Ribossômicas 70-kDa/metabolismo
18.
Environ Pollut ; 250: 118-126, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30991280

RESUMO

Metal-resistant bacteria can survive exposure to high metal concentrations without any negative impact on their growth. Biosorption is considered to be one of the more effective detoxification mechanisms acting in most bacteria. However, molecular-scale characterization of metal biosorption by wild metal-resistant bacteria has been limited. In this study, the Pb(II) biosorption behavior of Serratia Se1998 isolated from Pb-contaminated soil was investigated through macroscopic and microscopic techniques. A four discrete site non-electrostatic model fit the potentiometric titration data best, suggesting a distribution of phosphodiester, carboxyl, phosphoryl, and amino or hydroxyl groups on the cell surface. The presence of these functional groups was verified by the attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, which also indicated that carboxyl and phosphoryl sites participated in Pb(II) binding simultaneously. The negative enthalpy (-9.11 kJ mol-1) and large positive entropy (81.52 J mol-1 K-1) of Pb(II) binding with the bacteria suggested the formation of inner-sphere complexes by an exothermic process. X-ray absorption fine structure (XAFS) analysis further indicated monodentate inner-sphere binding of Pb(II) through formation of C-O-Pb and P-O-Pb bonds. We inferred that C-O-Pb bonds formed on the flagellar surfaces, establishing a self-protective barrier against exterior metal stressors. This study has important implications for an improved understanding of metal-resistance mechanisms in wild bacteria and provides guidance for the construction of genetically engineered bacteria for remediation purposes.


Assuntos
Bactérias/metabolismo , Metais/toxicidade , Espectroscopia de Infravermelho com Transformada de Fourier , Espectroscopia por Absorção de Raios X , Adsorção/fisiologia , Bactérias/crescimento & desenvolvimento , Farmacorresistência Bacteriana , Chumbo/toxicidade , Desintoxicação por Sorção
19.
Clin Exp Rheumatol ; 2019 Apr 11.
Artigo em Inglês | MEDLINE | ID: mdl-31025923

RESUMO

OBJECTIVES: Rheumatoid arthritis (RA) is characterised by the overproduction of autoantibodies such as rheumatoid factor (RF) and anti-cyclic citrullinated peptide (anti-CCP) antibody. T follicular helper (Tfh) cells are a specialised Th subset that provides signals to B cells, promoting the secretion of antibodies. Our previous studies showed that the frequency of circulating Tfh cells were markedly increased in RA patients and positively correlated with disease activity and the levels of anti-CCP autoantibody. Adiponectin (AD) is an adipokine secreted mainly by adipocytes. Our previous work has demonstrated that AD is highly expressed in the inflamed synovial joint tissue and correlates closely with progressive bone erosion in RA patients. However, it remains unknown whether AD aggravates the severity of RA via modulating Tfh cells. This study aims to investigate whether AD exerts effect on Tfh cells in RA. METHODS: CD4+ T cells were purified from peripheral blood mononuclear cells (PBMCs) of healthy controls (HC), and adiponectin receptor 1 (AdipoR1) expression on the surface of CD4+CXCR5+PD-1+ (Tfh) cells was detected by flow cytometry. Purified HC CD4+ T cells were cultured with different concentration fetal bovine serun (FBS) in the presence or absence of AD. The percentages of Tfh cells were analysed by flow cytometry. RA or osteoarthritis (OA) fibroblast-like synoviocytes (FLSs) were stimulated with AD for 72h and then co-cultured with HC CD4+ T cells through cell-to-cell contact or in a transwell system. The percentages of Tfh cells were analysed by flow cytometry and the levels of soluble factors such as interleukin-(IL)-6, IL-21, IL-12 and IFNγ in the supernatants were determined by Human Magnetic Bead Panel or Enzyme linked immunosorbent assay (ELISA). Then anti-IL-6 antibody and/or anti-IL-21 antibody was added to the co-culture system, and the percentages of Tfh cells were analysed by flow cytometry. The frequency of Tfh cells in the joint tissue of collagen-induced arthritis (CIA) mice was examined by flow cytometry. The mRNA expression of Tfh cell transcription factors and functional molecules such as B-cell lymphoma 6 (Bcl-6), B lymphocyte maturation protein 1 (Blimp-1), IL-6, IL-21, IL-12 and IFNγ in the joints of CIA mice were detected by real time PCR (RT-PCR). RESULTS: Adiponectin receptor 1 (AdipoR1) expression was detected on the surface of Tfh cells. However, in the present study, we did not find that AD has a direct effect on Tfh cell generation in vitro. Nonetheless, AD-stimulated RA FLSs could promote Tfh cell generation, predominantly via IL-6 production. And this upregulated effect was partially abolished upon neutralising IL-6. Finally, intraarticular injection of AD aggravated synovial inflammation with increased frequency of Tfh cells in the joints of AD-treated CIA mice. CONCLUSIONS: Our study demonstrated that AD-stimulated RA FLSs promote Tfh cell generation, which is mainly mediated by the secretion of soluble factor IL-6. This finding reveals a novel mechanism for AD in RA pathogenesis.

20.
J Hazard Mater ; 374: 26-34, 2019 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-30978627

RESUMO

Aqueous hexavalent chromium (Cr(VI)) poses serious threats to ecological environments. Magnetite is a potential adsorbent for Cr(VI). However, its adsorption capacity is limited due to the formation of Fe(III) oxide coating on magnetite surface. Herein, constant potential reduction was conducted to improve the Cr(VI) removal capacity of magnetite, and the influence of pH, potential, and supporting electrolytes including KNO3, KCl, and K2SO4 on the adsorption capacity was also investigated. The results showed that the highest Cr(VI) reduction percentage reached 93.7% with a total Cr removal capacity of 514.7 mg g-1 at optimized pH 2 and -0.2 V (vs. SCE) in supporting electrolyte of KNO3. Cr(VI) was reduced to Cr(III) on the surface of magnetite due to the direct electrochemical reduction at low potentials and reduction by Fe2+aq electrochemically generated from magnetite. The Cr(III) was subsequently removed and easily separated due to the formation of Cr(OH)3 precipitate on magnetite surface when KNO3 and KCl were used as supporting electrolyte; however, when K2SO4 was used instead, Cr(OH)3 precipitate was not observed. The decrease in pH and electrical potential was found to facilitate the reduction and removal of Cr(VI). This work proposes a facile method to enhance Cr(VI) removal by iron oxides.

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