Aiming to investigate the impacts of n-octanol addition on the oxidation reactivity,morphology and graphitization of diesel exhaust particles,soot samples were collected from a four-cylinder turbocharged diesel engine...Aiming to investigate the impacts of n-octanol addition on the oxidation reactivity,morphology and graphitization of diesel exhaust particles,soot samples were collected from a four-cylinder turbocharged diesel engine fueled with D100(neat diesel fuel),DO15(85%diesel and 15%n-octanol,V/V)and DO30(70%diesel and 30%n-octanol,V/V).All tests were conducted at two engine speeds of 1370 and 2150 r/min under a fixed torque of 125 N·m.The soot properties were characterized by thermogravimetric analyzer(TGA),transmission electron microscopy(TEM)and Raman spectroscopy(RS).The higher volatile organic fraction content,lower soot oxidation temperatures and lower activation energy from TGA results indicated that both the increasing n-octanol concentration and engine speed enhanced the soot oxidation reactivity.Additionally,quantitative analysis of TEM images showed that the soot derived from DO30 had the smallest primary particle diameters and fractal dimension,followed by those of soot produced by DO15 and D100.The RS results demonstrated that the n-octanol addition and higher engine speed led to a larger D1-FWHM(D1-full width at half maximum),A_(D1)/A_(T)(area ratio of D1 band and the total spectral)and A_(D3)/A_(T)(area ratio of D3 band and the total spectral)as well as a smaller L_(a)(crystallite width),revealing a lower degree of graphitization.Furthermore,the correlations between characterization parameters of soot properties and reactivity were nonlinear.展开更多
This study aims to analyze the influence of the polycyclic aromatic hydrocarbon(PAH)content in diesel on the physical and chemical properties of diesel soot particles.Four diesel fuels with different PAH content were ...This study aims to analyze the influence of the polycyclic aromatic hydrocarbon(PAH)content in diesel on the physical and chemical properties of diesel soot particles.Four diesel fuels with different PAH content were tested on a 11.6 L direct-injection diesel engine.The raw particulate matter(PM)before the after-treatment devices was collected using the thermophoresis sampling system and the filter sampling system.A transmission electron microscope and Raman spectrometer are used to analyze the physical properties of the soot particles,including morphology,primary particle size distribution,and graphitization degree.A Fourier transform infrared spectrometer and thermogravimetric analyzer are used to characterize the surface chemical composition and oxidation reactivity of soot particles,respectively.The results show that as the PAH content in the fuel decreases,the size of the primary soot particles decreases from 29.58 to 26.70 nm.The graphitization degree of soot particles first increases and then decreases,and the relative content of the aliphatic hydrocarbon functional groups of soot particles first decreases and then increases.The T_(10),T_(50),and T_(90) of soot from high-PAH fuel are 505.3,589.3,and 623.5℃,while those from low-PAH fuel are 480.1,557.5,and 599.2℃,respectively.This indicates that exhaust PM generated by the low-PAH fuel has poor oxidation reactivity.However,as the PAH content in fuel is further decreased,the excessively high cetane number may cause uneven mixing and incomplete combustion,leading to enhanced oxidation reactivity.展开更多
The aim of this study was to investigate the oxidation reactivity and behavior of exhaust particulate matter(PM)from diesel engines.PM samples from two diesel engines(1K,CY4102)with different emission levels were coll...The aim of this study was to investigate the oxidation reactivity and behavior of exhaust particulate matter(PM)from diesel engines.PM samples from two diesel engines(1K,CY4102)with different emission levels were collected by a thermophoretic system and a quartz filter.The oxidation reactivity,oxidation behaviors,and physicochemical properties of the PM samples were analyzed using thermogravimetric analysis(TGA),high-resolution transmission electron microscopy(HRTEM),Fourier-transform infrared spectrometry(FTIR),and Raman spectroscopy.The results showed that there was a great difference in the oxidation reactivity of soot particles emitted by the two different diesel engines.A qualitative analysis of the factors influencing oxidation reactivity showed that the nanostructure,degree of graphitization,and relative concentration of aliphatic C—H functional groups were the most important factors,whereas no significant correlation was found between the primary particle size and activation energy of the diesel soot.Based on the oxidation behavior analysis,the diesel soot particles exhibited both internal and surface oxidation modes during the oxidation process.Surface oxidation was dominant during the initial stage,and as oxidation progressed,the mode gradually changed to internal oxidation.Internal oxidation mode of soot particles from the 1K engine was significantly higher than that of CY4102.展开更多
Dimethyl carbonate(DMC)is an environmentally oxygenated compound which can be used efficiently for soot reduction.This paper compared the soot reduction,soot nanostructure and oxidation reactivity from inverse diffusi...Dimethyl carbonate(DMC)is an environmentally oxygenated compound which can be used efficiently for soot reduction.This paper compared the soot reduction,soot nanostructure and oxidation reactivity from inverse diffusion flames(IDFs)of the hydrocarbon fuels,namely n-heptane and isooctane doped with DMC.Effects of DMC additions on soot reduction were discussed.DMC addition is more effective for the soot reduction of n-heptane/DMC IDF than isooctane/DMC IDF.The morphology and nanostructures of soot particles were investigated by Transmission Electron Microscopy(TEM)and High Resolution TEM(HRTEM),and the soot graphitization and oxidation reactivity were analyzed by X-ray Diflfraction(XRD)and Thermogravimetric Analyzer(TGA),respectively.The results of HRTEM images showed that many larger aggregates were observed for the structures of soot particles from IDFs with DMC additions.The soot particles exhibited more liquid-like material,more amorphous,higher disorganized layers,and less graphitic than that of IDFs without DMC additions.With increasing of DMC blending rate,soot particles changed younger to have shorter fringe length,higher tortuosity,and greater fringe separation.Based on the XRD and TGA results,the degree of the soot graphitization level decreased;the soot mass lost significantly faster,and the soot become more reactive.展开更多
The extensive use of tetracycline hydrochloride(TCH)poses a threat to human health and the aquatic environment.Here,magnetic p-n Bi2WO6/CuFe2O4 catalyst was fabricated to efficiently remove TCH.The obtained Bi2WO6/CuF...The extensive use of tetracycline hydrochloride(TCH)poses a threat to human health and the aquatic environment.Here,magnetic p-n Bi2WO6/CuFe2O4 catalyst was fabricated to efficiently remove TCH.The obtained Bi2WO6/CuFe2O4 exhibited 92.1%TCH degradation efficiency and 50.7%and 35.1%mineralization performance for TCH and raw secondary effluent from a wastewater treatment plant in a photo-Fenton-like system,respectively.The remarkable performance was attributed to the fact that photogenerated electrons accelerated the Fe(III)/Fe(II)and Cu(II)/Cu(I)conversion for the Fenton-like reaction between Fe(II)/Cu(I)and H2O2,thereby generating abundant·OH for pollutant oxidation.Various environmental factors including H2O2 concentration,initial pH,catalyst dosage,TCH concentration and inorganic ions were explored.The reactive oxidation species(ROS)quenching results and electron spin resonance(ESR)spectra confirmed that·O2-and·OH were responsible for the dark and photo-Fenton-like systems,respectively.The degradation mechanisms and pathways of TCH were proposed,and the toxicity of products was evaluated.This work contributes a highly efficient and environmentally friendly catalyst and provides a clear mechanistic explanation for the removal of antibiotic pollutants in environmental remediation.展开更多
Self-limiting oxidation of nanowires has been previously described as a reaction- or diffusion-controlled process. In this letter, the concept of finite reactive region is introduced into a diffusion-controlled model,...Self-limiting oxidation of nanowires has been previously described as a reaction- or diffusion-controlled process. In this letter, the concept of finite reactive region is introduced into a diffusion-controlled model, based upon which a two-dimensional cylindrical kinetics model is developed for the oxidation of silicon nanowires and is extended for tungsten. In the model, diffusivity is affected by the expansive oxidation reaction induced stress. The dependency of the oxidation upon curvature and temperature is modeled. Good agreement between the model predictions and available experimental data is obtained. The de- veloped model serves to quantify the oxidation in two-dimensional nanostructures and is expected to facilitate their fabrication via thermal oxidation techniques.展开更多
The Cr-/Si-modified Ni Al Hf coatings were produced on single-crystal（SC） superalloy N5 by electron beam physical vapor deposition（EB-PVD）. The cyclic oxidation behavior of the coatings at 1100 °C was investi...The Cr-/Si-modified Ni Al Hf coatings were produced on single-crystal（SC） superalloy N5 by electron beam physical vapor deposition（EB-PVD）. The cyclic oxidation behavior of the coatings at 1100 °C was investigated. The microstructures of the oxide scales grown on the coatings were characterized by scanning electron microscope（SEM） with energy-dispersive X-ray spectrum（EDX）,electron probe micro-analyzer（EPMA） and X-ray diffraction（XRD）. The effects of Cr and Si on the cyclic oxidation behavior of the Ni Al Hf coatings were discussed. The addition of Si to the Ni Al Hf Cr coating not only reduces the oxidation rate but also enhances the oxide scale adherence.Owing to the addition of Si in the coating, the segregation of Cr and Mo beneath the oxide scale is effectively avoided,which contributes to enhancing oxide scale adherence.展开更多
As a case study, refined iron（Fe） speciation and quantitative characterization of the reductive reactivity of Fe（Ⅲ）oxides are combined to investigate Fe diagenetic processes in a core sediment from the eutrophic ...As a case study, refined iron（Fe） speciation and quantitative characterization of the reductive reactivity of Fe（Ⅲ）oxides are combined to investigate Fe diagenetic processes in a core sediment from the eutrophic Jiaozhou Bay.The results show that a combination of the two methods can trace Fe transformation in more detail and offer nuanced information on Fe diagenesis from multiple perspectives. This methodology may be used to enhance our understanding of the complex biogeochemical cycling of Fe and sulfur in other studies. Microbial iron reduction（MIR） plays an important role in Fe（Ⅲ） reduction over the upper sediments, while a chemical reduction by reaction with dissolved sulfide is the main process at a deeper（〉 12 cm） layer. The most bioavailable amorphous Fe（Ⅲ） oxides [Fe（Ⅲ）am] are the main source of the MIR, followed by poorly crystalline Fe（Ⅲ） oxides [Fe（Ⅲ）pc）]and magnetite. Well crystalline Fe（Ⅲ） oxides [Fe（Ⅲ）wc] have barely participated in Fe diagenesis. The importance of the MIR over the upper layer may be a combined result of the high availability of highly reactive Fe oxides and low availability of labile organic matter, and the latter is also the ultimate factor limiting sulfate reduction and sulfide accumulation in the sediments. Microbially reducible Fe（Ⅲ） [MR-Fe（Ⅲ）], which is quantified by kinetics of Fe（II）-oxide reduction, mainly consists of the most reactive Fe（Ⅲ）am and less reactive Fe（Ⅲ）pc. The bulk reactivity of the MR-Fe（Ⅲ） pool is equivalent to aged ferrihydrite, and shows down-core decrease due to preferential reduction of highly reactive phases of Fe oxides.展开更多
The reactions of anionic zirconium oxide clusters ZrxOy- with C2H6 and C4H10 are investi-gated by a time of flight mass spectrometer coupled with a laser vaporization cluster source.Hydrogen containing products Zr2O5H...The reactions of anionic zirconium oxide clusters ZrxOy- with C2H6 and C4H10 are investi-gated by a time of flight mass spectrometer coupled with a laser vaporization cluster source.Hydrogen containing products Zr2O5H- and Zr3O7H- are observed after the reaction. Den-sity functional theory calculations indicate that the hydrogen abstraction is favorable in the reaction of Zr2O5- with C2H6, which supports that the observed Zr2O5H- and Zr3O7H- are due to hydrogen atom abstraction from the alkane molecules. This work shows a newpossible pathway in the reaction of zirconium oxide cluster anions with alkane molecules.展开更多
To investigate the hypothesis that treatment with dimethyl fumarate (DMF) may ameliorate liver ischemia/reperfusion injury (I/RI). METHODSRats were divided into 3 groups: sham, control (CTL), and DMF. DMF (25 mg/kg, t...To investigate the hypothesis that treatment with dimethyl fumarate (DMF) may ameliorate liver ischemia/reperfusion injury (I/RI). METHODSRats were divided into 3 groups: sham, control (CTL), and DMF. DMF (25 mg/kg, twice/d) was orally administered for 2 d before the procedure. The CTL and DMF rats were subjected to ischemia for 1 h and reperfusion for 2 h. The serum alanine aminotransferase (ALT) and malondialdehyde (MDA) levels, adenosine triphosphate (ATP), NO × metabolites, anti-oxidant enzyme expression level, anti-inflammatory effect, and anti-apoptotic effect were determined. RESULTSHistological tissue damage was significantly reduced in the DMF group (Suzuki scores: sham: 0 ± 0; CTL: 9.3 ± 0.5; DMF: 2.5 ± 1.2; sham vs CTL, P < 0.0001; CTL vs DMF, P < 0.0001). This effect was associated with significantly lower serum ALT (DMF 5026 ± 2305 U/L vs CTL 10592 ± 1152 U/L, P = 0.04) and MDA (DMF 18.2 ± 1.4 μmol/L vs CTL 26.0 ± 1.0 μmol/L, P = 0.0009). DMF effectively improved the ATP content (DMF 20.3 ± 0.4 nmol/mg vs CTL 18.3 ± 0.6 nmol/mg, P = 0.02), myeloperoxidase activity (DMF 7.8 ± 0.4 mU/mL vs CTL 6.0 ± 0.5 mU/mL, P = 0.01) and level of endothelial nitric oxide synthase expression (DMF 0.38 ± 0.05-fold vs 0.17 ± 0.06-fold, P = 0.02). The higher expression levels of anti-oxidant enzymes (catalase and glutamate-cysteine ligase modifier subunit and lower levels of key inflammatory mediators (nuclear factor-kappa B and cyclooxygenase-2 were confirmed in the DMF group. CONCLUSIONDMF improved the liver function and the anti-oxidant and inflammation status following I/RI. Treatment with DMF could be a promising strategy in patients with liver I/RI.展开更多
AIM: To investigate the mechanism of endoplasmic reticulum(ER) stress induction by an occult infection related hepatitis B virus S surface antigen(HBsAg)variant.METHODS: We used an HBsAg variant with lower secretion c...AIM: To investigate the mechanism of endoplasmic reticulum(ER) stress induction by an occult infection related hepatitis B virus S surface antigen(HBsAg)variant.METHODS: We used an HBsAg variant with lower secretion capacity, which was a KD variant from a Korean subject who was occultly infected with the genotype C. We compared the expression profiles of ER stress-related proteins between HuH-7 cells transfected with HBsAg plasmids of a wild-type and a KD variant using Western blot.RESULTS: Confocal microscopy indicated that the KD variant had higher levels of co-localization with ER than the wild-type HBsAg. The KD variant upregulated ER stress-related proteins and induced reactive oxygen species(ROS) compared to the wildtype via an increase in calcium. The KD variant also down-regulated anti-oxidant proteins(HO-1, catalase and SOD) compared to the wild-type, which indicates positive amplification loops of the ER-ROS axis. The KD variant also induced apoptotic cell death via the upregulation of caspase proteins(caspase 6, 9 and 12).Furthermore, the KD variant induced a higher level of nitric oxide than wild-type HBsAg via the up-regulation of the iNOS protein.CONCLUSION: Our data indicate that occult infection related HBsAg variants can lead to ER-derived oxidative stress and liver cell death in HuH-7 cells.展开更多
Amyloid beta（Aβ）-induced oxidative stress is a major pathologic hallmark of Alzheimer＇s disease. Cyanidin, a natural flavonoid compound, is neuroprotective against oxidative damage-mediated degeneration. However, ...Amyloid beta（Aβ）-induced oxidative stress is a major pathologic hallmark of Alzheimer＇s disease. Cyanidin, a natural flavonoid compound, is neuroprotective against oxidative damage-mediated degeneration. However, its molecular mechanism remains unclear. Here, we investigated the effects of cyanidin pretreatment against Aβ-induced neurotoxicity in PC12 cells, and explored the underlying mechanisms. Cyanidin pretreatment significantly attenuated Aβ-induced cell mortality and morphological changes in PC12 cells. Mechanistically, cyanidin effectively blocked apoptosis induced by Aβ, by restoring the mitochondrial membrane potential via upregulation of Bcl-2 protein expression. Moreover, cyanidin markedly protected PC12 cells from Aβ-induced DNA damage by blocking reactive oxide species and superoxide accumulation. These results provide evidence that cyanidin suppresses Aβ-induced cytotoxicity, by preventing oxidative damage mediated by reactive oxide species, which in turn inhibits mitochondrial apoptosis. Our study demonstrates the therapeutic potential of cyanidin in the prevention of oxidative stress-mediated Aβ neurotoxicity.展开更多
With continuous population and economic growth in the 21st century,plastic pollution is a major global issue.However,the health concern of microplastics/nanoplastics(MPs/NPs)decomposed from plastic wastes has drawn pu...With continuous population and economic growth in the 21st century,plastic pollution is a major global issue.However,the health concern of microplastics/nanoplastics(MPs/NPs)decomposed from plastic wastes has drawn public attention only in the recent decade.This article summarizes recent works dedicated to understanding the impact of MPs/NPs on the liver-the largest digestive organ,which is one of the primary routes that MPs/NPs enter human bodies.The interrelated mechanisms including oxidative stress,hepatocyte energy re-distribution,cell death and autophagy,as well as immune responses and inflammation,were also featured.In addition,the disturbance of microbiome and gut-liver axis,and the association with clinical diseases such as metabolic dysfunction-associated fatty liver disease,steatohepatitis,liver fibrosis,and cirrhosis were briefly discussed.Finally,we discussed potential directions in regard to this trending topic,highlighted current challenges in research,and proposed possible solutions.展开更多
This study was aimed at evaluating the anti-diabetic potential of passion fruit Passiflora edulis(EPE) extracts in diabetic rats, following Streptozotocin(STZ) induced oxidative stress. Thirty adult Wistar rats were d...This study was aimed at evaluating the anti-diabetic potential of passion fruit Passiflora edulis(EPE) extracts in diabetic rats, following Streptozotocin(STZ) induced oxidative stress. Thirty adult Wistar rats were divided into five groups, with six rats in each group. The control rats were injected intraperitoneally with citrate buffer(pH 4.5). The remaining groups of rats were administered single dose of 45 mg·kg-1 of STZ by intraperitoneal route to induce diabetes. The diabetic animals were treated with 250 and 500 mg·kg-1 of EPE and glibenclamide 0.6 mg·kg-1 for fifteen days by oral route. Blood glucose, end organ oxidative stress marker, and anti-oxidants were assayed. Further, histopathological investigation of pancreas was studied at the end of the experimentation. The results revealed that subacute administration of EPE significantly(P < 0.001) controlled the blood glucose level in the diabetic rats. In addition, EPE extract protected the end organs by restoring the anti-oxidants enzyme, significantly increasing super oxide dismutase level(SOD) and decreasing catalase(CAT) and TBARS level in visceral organs. In conclusion, that EPE extracts showed anti-diabetic and anti-oxidant potential against streptozotocin-induced diabetes.展开更多
Halobenzoquinones（HBQs） are an emerging class of halogenated disinfection byproducts（DBPs） in drinking water, which raised public concerns due to potential carcinogenic effects to human bladder. Our previous work ...Halobenzoquinones（HBQs） are an emerging class of halogenated disinfection byproducts（DBPs） in drinking water, which raised public concerns due to potential carcinogenic effects to human bladder. Our previous work demonstrated that HBQs and hydrogen peroxide（H_2O_2）together generated oxidative DNA damage via a metal-independent and intercalationenhanced oxidation mechanism in vitro. This study further investigated the efficiency of various HBQs to induce oxidative DNA damage in T24 bladder cancer cells. Compared with T24 cells without treatment（3.1 lesions per 10~6 d G）, the level of 8-oxo-7,8-dihydro-2′-deoxyguanosine（8-oxod G） significantly increased by 1.4, 3.2, 8.8, and 9.2 times after treatment with tetrabromo-1,4-benzoquinone（TBBQ）, terachloro-1,4-benzoquinone（TCBQ）,2,6-dichloro-1,4-benzoquinone（2,6-DCBQ） and 2,5-dichloro-1,4-benzoquinone（2,5-DCBQ） for24 hr, respectively. Interestingly, we found that the oxidative potency of HBQs in T24 cells（2,5-DCBQ ≈ 2,6-DCBQ 〉 TCBQ 〉 TBBQ） is inconsistent with that of in vitro ds DNA oxidation（TCBQ 〉 TBBQ 〉 2,5-DCBQ 〉 2,6-DCBQ）, suggesting HBQs induce oxidative lesions in cellular genomic DNA probably involved with a complex mechanism.展开更多
Programmed cell death occurs in browning explants of Fraxinus mandshurica during somatic embryogenesis, but the underlying mechanism is unclear. In this study, single cotyledons of zygotic embryos of F. mandshurica we...Programmed cell death occurs in browning explants of Fraxinus mandshurica during somatic embryogenesis, but the underlying mechanism is unclear. In this study, single cotyledons of zygotic embryos of F. mandshurica were used as explants. Mitochondrial structure and function, caspase-3-like protease activity, hydrogen peroxide metabolism, and nitric oxide accumulation induced by high concentrations of sucrose and plant growth regulators were studied. The results show that plant growth regulators induced somatic embryogenesis and also promoted explant browning. High sucrose concentrations had similar effects. High concentrations of sucrose and plant growth regulators led to the accumulation of hydrogen peroxide and nitric oxide which induced changes in mitochondrial structure and function such as modifications in mitochondrial morphology, increased membrane permeability, decreased membrane potential, and the release of cytochrome c into the cytoplasm. An increase in caspase-3-like protease activity triggered programmed cell death in some browning explant cells. During somatic embryogenesis there were increased activities of superoxide dismutase, peroxidase, and catalase, which are associated with hydrogen peroxide metabolism and jointly maintain reactive oxygen species levels. Intracellular nitric oxide synthase and nitrate reductase activities were not significantly correlated with nitric oxide content. Instead, intracellular nitric oxide may be derived from non-enzymatic reactions. Our results indicate that hydrogen peroxide and nitric oxide may function as signals, playing key roles in somatic embryogenesis and programmed cell death of explant cells of F. mandshurica. The interaction between nitric oxide and reactive oxygen species determines the occurrence of programmed cell death in explant cells;somatic embryogenesis and programmed cell death are positively regulated by hydrogen peroxide. However, the regulation of nitric oxide is complex.展开更多
Per-and polyfluoroalkyl substances(PFAS)are found to have multiple adverse outcomes on human health.Recently,epidemiological and toxicological studies showed that exposure to PFAS had adverse impacts on pancreas and s...Per-and polyfluoroalkyl substances(PFAS)are found to have multiple adverse outcomes on human health.Recently,epidemiological and toxicological studies showed that exposure to PFAS had adverse impacts on pancreas and showed association with insulin abnormalities.To explore how PFAS may contribute to diabetes,we studied impacts of perfluorooctane sul-fonate(PFOS)on cell viability and insulin release capacity of pancreatic β cells by using in vivo and in vitro methods.We found that 28-day administration with PFOS(10 mg/(kg body weight·day))caused reductions of pancreas weight and islet size in male mice.PFOS admin-istration also led to lower serum insulin level both in fasting state and after glucose infusion among male mice.For cell-based in vitro bioassay,we used mouse β-TC-6 cancer cells and found 48-hr exposure to PFOS decreased the cell viability at 50 μmol/L.By measuring insulin content in supernatant,48-hr pretreatment of PFOS(100 μmol/L)decreased the insulin re-lease capacity of β-TC-6 cells after glucose stimulation.Although these concentrations were higher than the environmental concentration of PFOS,it might be reasonable for high con-centration of PFOS to exert observable toxic effects in mice considering mice had a faster removal efficiency of PFOS than human.PFOS exposure(50 μmol/L)to β-TC-6 cells induced intracellular accumulation of reactive oxidative specie(ROS).Excessive ROS induced the re-active toxicity of cells,which eventually invoke apoptosis and necrosis.Results in this study provide evidence for the possible causal link of exposure to PFOS and diabetes risk.展开更多
Heavy metal pollution has become a worldwide problem in aquaculture. We studied copper （Cu^2＋） accumulation and physiological responses of two red algae Gracilaria lemaneiformis and Gracilaria lichenoides from Chin...Heavy metal pollution has become a worldwide problem in aquaculture. We studied copper （Cu^2＋） accumulation and physiological responses of two red algae Gracilaria lemaneiformis and Gracilaria lichenoides from China under Cu^2＋ exposure of 0-500 μg/L in concentration. Compared with G. lemaneiformis, G. lichenoides was more capable in accumulating Cu^2＋, specifically, more Cu〉 on extracellular side （cell wall） than on intracellular side （cytoplasm） and in cell organelles （especially chloroplast, cell nucleus, mitochondria, and ribosome）. In addition, G. lichenoides contained more insoluble polysaccharide in cell wall, which might promote the extracellular Cu^2＋-binding as an efficient barrier against metal toxicity. Conversely, G. lemaneiformis was more vulnerable than G. lichenoides to Cu^2＋ toxin for decreases in growth, pigment （chlorophyll a, chlorophyll b, phycobiliprotein, and B-carotene） content, and photosynthetic activity. Moreover, more serious oxidative damages in G. lemaneiformis than in G. lichenoides, in accumulation of reactive oxidative species and malondialdehyde, and in electrolyte leakage, because of lower antioxidant enzyme （superoxide dismutase and glutathione reductase） activities. Therefore, G. lichenoides was less susceptible to Cu〉 stress than G. lemaneiformis.展开更多
Postoperative cognitive dysfunction is a crucial public health issue that has been increasingly studied in efforts to reduce symptoms or prevent its occurrence. However, effective advances remain lacking. Hyperbaric o...Postoperative cognitive dysfunction is a crucial public health issue that has been increasingly studied in efforts to reduce symptoms or prevent its occurrence. However, effective advances remain lacking. Hyperbaric oxygen preconditioning has proved to protect vital organs, such as the heart, liver, and brain. Recently, it has been introduced and widely studied in the prevention of postoperative cognitive dysfunction, with promising results. However, the neuroprotective mechanisms underlying this phenomenon remain controversial. This review summarizes and highlights the definition and application of hyperbaric oxygen preconditioning, the perniciousness and pathogenetic mechanism underlying postoperative cognitive dysfunction, and the effects that hyperbaric oxygen preconditioning has on postoperative cognitive dysfunction. Finally, we conclude that hyperbaric oxygen preconditioning is an effective and feasible method to prevent, alleviate, and improve postoperative cognitive dysfunction, and that its mechanism of action is very complex, involving the stimulation of endogenous antioxidant and anti-inflammation defense systems.展开更多
Objective To investigate whether intracellular amyloid β （iAβ） induces toxicity in wild type （WT） and APP/PS1 mice, a mouse model of Alzheimer＇s disease. Methods Different forms of Aβ aggregates were microinje...Objective To investigate whether intracellular amyloid β （iAβ） induces toxicity in wild type （WT） and APP/PS1 mice, a mouse model of Alzheimer＇s disease. Methods Different forms of Aβ aggregates were microinjected into cultured WT or APP/PS1 mouse hippocampal neurons. TUNEL staining was performed to examine neuronal cell death. Reactive oxidative species （ROS） were measured by MitoSOXTM Red mitochondrial superoxide indicator. Results Crude, monomer and protofibrilAβ induced more toxicity inAPP/PS1 neurons than in WT neurons. ROS are involved in mediating the vulnerability of APP/PS1 neurons to iAβ toxicity. Conclusion Oxidative stress may mediate cell death induced by iAβ in neurons.展开更多
基金supported by National Natural Science Foundation of China(No.51776162)Natural Science Basic Research Program of Shaanxi(No.2020JM-044)Fundamental Research Funds for the Central Universities(No.xzy032019002)。
文摘Aiming to investigate the impacts of n-octanol addition on the oxidation reactivity,morphology and graphitization of diesel exhaust particles,soot samples were collected from a four-cylinder turbocharged diesel engine fueled with D100(neat diesel fuel),DO15(85%diesel and 15%n-octanol,V/V)and DO30(70%diesel and 30%n-octanol,V/V).All tests were conducted at two engine speeds of 1370 and 2150 r/min under a fixed torque of 125 N·m.The soot properties were characterized by thermogravimetric analyzer(TGA),transmission electron microscopy(TEM)and Raman spectroscopy(RS).The higher volatile organic fraction content,lower soot oxidation temperatures and lower activation energy from TGA results indicated that both the increasing n-octanol concentration and engine speed enhanced the soot oxidation reactivity.Additionally,quantitative analysis of TEM images showed that the soot derived from DO30 had the smallest primary particle diameters and fractal dimension,followed by those of soot produced by DO15 and D100.The RS results demonstrated that the n-octanol addition and higher engine speed led to a larger D1-FWHM(D1-full width at half maximum),A_(D1)/A_(T)(area ratio of D1 band and the total spectral)and A_(D3)/A_(T)(area ratio of D3 band and the total spectral)as well as a smaller L_(a)(crystallite width),revealing a lower degree of graphitization.Furthermore,the correlations between characterization parameters of soot properties and reactivity were nonlinear.
基金National Key Research and Development Program of China(2017YFB0306605)Key Laboratory of Engines at Tianjin University(Grant No.K2022-06).
文摘This study aims to analyze the influence of the polycyclic aromatic hydrocarbon(PAH)content in diesel on the physical and chemical properties of diesel soot particles.Four diesel fuels with different PAH content were tested on a 11.6 L direct-injection diesel engine.The raw particulate matter(PM)before the after-treatment devices was collected using the thermophoresis sampling system and the filter sampling system.A transmission electron microscope and Raman spectrometer are used to analyze the physical properties of the soot particles,including morphology,primary particle size distribution,and graphitization degree.A Fourier transform infrared spectrometer and thermogravimetric analyzer are used to characterize the surface chemical composition and oxidation reactivity of soot particles,respectively.The results show that as the PAH content in the fuel decreases,the size of the primary soot particles decreases from 29.58 to 26.70 nm.The graphitization degree of soot particles first increases and then decreases,and the relative content of the aliphatic hydrocarbon functional groups of soot particles first decreases and then increases.The T_(10),T_(50),and T_(90) of soot from high-PAH fuel are 505.3,589.3,and 623.5℃,while those from low-PAH fuel are 480.1,557.5,and 599.2℃,respectively.This indicates that exhaust PM generated by the low-PAH fuel has poor oxidation reactivity.However,as the PAH content in fuel is further decreased,the excessively high cetane number may cause uneven mixing and incomplete combustion,leading to enhanced oxidation reactivity.
基金the SINOPEC(124015)and the State Key Laboratory of Engines at Tianjin University(No.K2022-06).
文摘The aim of this study was to investigate the oxidation reactivity and behavior of exhaust particulate matter(PM)from diesel engines.PM samples from two diesel engines(1K,CY4102)with different emission levels were collected by a thermophoretic system and a quartz filter.The oxidation reactivity,oxidation behaviors,and physicochemical properties of the PM samples were analyzed using thermogravimetric analysis(TGA),high-resolution transmission electron microscopy(HRTEM),Fourier-transform infrared spectrometry(FTIR),and Raman spectroscopy.The results showed that there was a great difference in the oxidation reactivity of soot particles emitted by the two different diesel engines.A qualitative analysis of the factors influencing oxidation reactivity showed that the nanostructure,degree of graphitization,and relative concentration of aliphatic C—H functional groups were the most important factors,whereas no significant correlation was found between the primary particle size and activation energy of the diesel soot.Based on the oxidation behavior analysis,the diesel soot particles exhibited both internal and surface oxidation modes during the oxidation process.Surface oxidation was dominant during the initial stage,and as oxidation progressed,the mode gradually changed to internal oxidation.Internal oxidation mode of soot particles from the 1K engine was significantly higher than that of CY4102.
基金This work was supported by the National Natural Science Foundation of China(51706103,51822605,51776181)the Fundamental Research Funds for the Central Universities,China(CEPE2019010,30920031103)+1 种基金the Open Project of State Key Laboratory of Clean Energy Utilization,Zhejiang University,China(ZJUCEU2017011)Bo Jiang thanks the great support given by the China Scholarship Council(201906845024).
文摘Dimethyl carbonate(DMC)is an environmentally oxygenated compound which can be used efficiently for soot reduction.This paper compared the soot reduction,soot nanostructure and oxidation reactivity from inverse diffusion flames(IDFs)of the hydrocarbon fuels,namely n-heptane and isooctane doped with DMC.Effects of DMC additions on soot reduction were discussed.DMC addition is more effective for the soot reduction of n-heptane/DMC IDF than isooctane/DMC IDF.The morphology and nanostructures of soot particles were investigated by Transmission Electron Microscopy(TEM)and High Resolution TEM(HRTEM),and the soot graphitization and oxidation reactivity were analyzed by X-ray Diflfraction(XRD)and Thermogravimetric Analyzer(TGA),respectively.The results of HRTEM images showed that many larger aggregates were observed for the structures of soot particles from IDFs with DMC additions.The soot particles exhibited more liquid-like material,more amorphous,higher disorganized layers,and less graphitic than that of IDFs without DMC additions.With increasing of DMC blending rate,soot particles changed younger to have shorter fringe length,higher tortuosity,and greater fringe separation.Based on the XRD and TGA results,the degree of the soot graphitization level decreased;the soot mass lost significantly faster,and the soot become more reactive.
基金supported by the National Natural Science Foundation of China(Nos.51678270,21872063)111 Project of Jilin University,China(No.B16020)。
文摘The extensive use of tetracycline hydrochloride(TCH)poses a threat to human health and the aquatic environment.Here,magnetic p-n Bi2WO6/CuFe2O4 catalyst was fabricated to efficiently remove TCH.The obtained Bi2WO6/CuFe2O4 exhibited 92.1%TCH degradation efficiency and 50.7%and 35.1%mineralization performance for TCH and raw secondary effluent from a wastewater treatment plant in a photo-Fenton-like system,respectively.The remarkable performance was attributed to the fact that photogenerated electrons accelerated the Fe(III)/Fe(II)and Cu(II)/Cu(I)conversion for the Fenton-like reaction between Fe(II)/Cu(I)and H2O2,thereby generating abundant·OH for pollutant oxidation.Various environmental factors including H2O2 concentration,initial pH,catalyst dosage,TCH concentration and inorganic ions were explored.The reactive oxidation species(ROS)quenching results and electron spin resonance(ESR)spectra confirmed that·O2-and·OH were responsible for the dark and photo-Fenton-like systems,respectively.The degradation mechanisms and pathways of TCH were proposed,and the toxicity of products was evaluated.This work contributes a highly efficient and environmentally friendly catalyst and provides a clear mechanistic explanation for the removal of antibiotic pollutants in environmental remediation.
基金financial support of this work by the National Natural Science Foundation of China(11472149)the Tsinghua University Initiative Scientific Research Program(2014z22074)
文摘Self-limiting oxidation of nanowires has been previously described as a reaction- or diffusion-controlled process. In this letter, the concept of finite reactive region is introduced into a diffusion-controlled model, based upon which a two-dimensional cylindrical kinetics model is developed for the oxidation of silicon nanowires and is extended for tungsten. In the model, diffusivity is affected by the expansive oxidation reaction induced stress. The dependency of the oxidation upon curvature and temperature is modeled. Good agreement between the model predictions and available experimental data is obtained. The de- veloped model serves to quantify the oxidation in two-dimensional nanostructures and is expected to facilitate their fabrication via thermal oxidation techniques.
基金financially supported by the National Basic Research Program of China (Nos. 2012CB625100 and 2010CB631200)the National Natural Science Foundation of China (No. 51231001)
文摘The Cr-/Si-modified Ni Al Hf coatings were produced on single-crystal（SC） superalloy N5 by electron beam physical vapor deposition（EB-PVD）. The cyclic oxidation behavior of the coatings at 1100 °C was investigated. The microstructures of the oxide scales grown on the coatings were characterized by scanning electron microscope（SEM） with energy-dispersive X-ray spectrum（EDX）,electron probe micro-analyzer（EPMA） and X-ray diffraction（XRD）. The effects of Cr and Si on the cyclic oxidation behavior of the Ni Al Hf coatings were discussed. The addition of Si to the Ni Al Hf Cr coating not only reduces the oxidation rate but also enhances the oxide scale adherence.Owing to the addition of Si in the coating, the segregation of Cr and Mo beneath the oxide scale is effectively avoided,which contributes to enhancing oxide scale adherence.
基金The National Natural Science Foundation of China under contract Nos 41576078 and 41276069the Shandong Province Natural Science Foundation of China under contract No.ZR2015DM006the National Key Research and Development Program of China under contract No.2016YFA0601301
文摘As a case study, refined iron（Fe） speciation and quantitative characterization of the reductive reactivity of Fe（Ⅲ）oxides are combined to investigate Fe diagenetic processes in a core sediment from the eutrophic Jiaozhou Bay.The results show that a combination of the two methods can trace Fe transformation in more detail and offer nuanced information on Fe diagenesis from multiple perspectives. This methodology may be used to enhance our understanding of the complex biogeochemical cycling of Fe and sulfur in other studies. Microbial iron reduction（MIR） plays an important role in Fe（Ⅲ） reduction over the upper sediments, while a chemical reduction by reaction with dissolved sulfide is the main process at a deeper（〉 12 cm） layer. The most bioavailable amorphous Fe（Ⅲ） oxides [Fe（Ⅲ）am] are the main source of the MIR, followed by poorly crystalline Fe（Ⅲ） oxides [Fe（Ⅲ）pc）]and magnetite. Well crystalline Fe（Ⅲ） oxides [Fe（Ⅲ）wc] have barely participated in Fe diagenesis. The importance of the MIR over the upper layer may be a combined result of the high availability of highly reactive Fe oxides and low availability of labile organic matter, and the latter is also the ultimate factor limiting sulfate reduction and sulfide accumulation in the sediments. Microbially reducible Fe（Ⅲ） [MR-Fe（Ⅲ）], which is quantified by kinetics of Fe（II）-oxide reduction, mainly consists of the most reactive Fe（Ⅲ）am and less reactive Fe（Ⅲ）pc. The bulk reactivity of the MR-Fe（Ⅲ） pool is equivalent to aged ferrihydrite, and shows down-core decrease due to preferential reduction of highly reactive phases of Fe oxides.
基金This work was supported by the Chinese Academy of Sciences （Hundred Talents Fund）, the National Natural Science Foundation of China （No.20703048 and No.20803083）, and the Center of Molecular Science Foundation of Institute of Chemistry, Chinese Academy of Sciences （No.CMS-LX200902）.
文摘The reactions of anionic zirconium oxide clusters ZrxOy- with C2H6 and C4H10 are investi-gated by a time of flight mass spectrometer coupled with a laser vaporization cluster source.Hydrogen containing products Zr2O5H- and Zr3O7H- are observed after the reaction. Den-sity functional theory calculations indicate that the hydrogen abstraction is favorable in the reaction of Zr2O5- with C2H6, which supports that the observed Zr2O5H- and Zr3O7H- are due to hydrogen atom abstraction from the alkane molecules. This work shows a newpossible pathway in the reaction of zirconium oxide cluster anions with alkane molecules.
文摘To investigate the hypothesis that treatment with dimethyl fumarate (DMF) may ameliorate liver ischemia/reperfusion injury (I/RI). METHODSRats were divided into 3 groups: sham, control (CTL), and DMF. DMF (25 mg/kg, twice/d) was orally administered for 2 d before the procedure. The CTL and DMF rats were subjected to ischemia for 1 h and reperfusion for 2 h. The serum alanine aminotransferase (ALT) and malondialdehyde (MDA) levels, adenosine triphosphate (ATP), NO × metabolites, anti-oxidant enzyme expression level, anti-inflammatory effect, and anti-apoptotic effect were determined. RESULTSHistological tissue damage was significantly reduced in the DMF group (Suzuki scores: sham: 0 ± 0; CTL: 9.3 ± 0.5; DMF: 2.5 ± 1.2; sham vs CTL, P < 0.0001; CTL vs DMF, P < 0.0001). This effect was associated with significantly lower serum ALT (DMF 5026 ± 2305 U/L vs CTL 10592 ± 1152 U/L, P = 0.04) and MDA (DMF 18.2 ± 1.4 μmol/L vs CTL 26.0 ± 1.0 μmol/L, P = 0.0009). DMF effectively improved the ATP content (DMF 20.3 ± 0.4 nmol/mg vs CTL 18.3 ± 0.6 nmol/mg, P = 0.02), myeloperoxidase activity (DMF 7.8 ± 0.4 mU/mL vs CTL 6.0 ± 0.5 mU/mL, P = 0.01) and level of endothelial nitric oxide synthase expression (DMF 0.38 ± 0.05-fold vs 0.17 ± 0.06-fold, P = 0.02). The higher expression levels of anti-oxidant enzymes (catalase and glutamate-cysteine ligase modifier subunit and lower levels of key inflammatory mediators (nuclear factor-kappa B and cyclooxygenase-2 were confirmed in the DMF group. CONCLUSIONDMF improved the liver function and the anti-oxidant and inflammation status following I/RI. Treatment with DMF could be a promising strategy in patients with liver I/RI.
基金Supported by National Research Foundation of Korea grant funded by the Korea government(MEST),No.2013-005810
文摘AIM: To investigate the mechanism of endoplasmic reticulum(ER) stress induction by an occult infection related hepatitis B virus S surface antigen(HBsAg)variant.METHODS: We used an HBsAg variant with lower secretion capacity, which was a KD variant from a Korean subject who was occultly infected with the genotype C. We compared the expression profiles of ER stress-related proteins between HuH-7 cells transfected with HBsAg plasmids of a wild-type and a KD variant using Western blot.RESULTS: Confocal microscopy indicated that the KD variant had higher levels of co-localization with ER than the wild-type HBsAg. The KD variant upregulated ER stress-related proteins and induced reactive oxygen species(ROS) compared to the wildtype via an increase in calcium. The KD variant also down-regulated anti-oxidant proteins(HO-1, catalase and SOD) compared to the wild-type, which indicates positive amplification loops of the ER-ROS axis. The KD variant also induced apoptotic cell death via the upregulation of caspase proteins(caspase 6, 9 and 12).Furthermore, the KD variant induced a higher level of nitric oxide than wild-type HBsAg via the up-regulation of the iNOS protein.CONCLUSION: Our data indicate that occult infection related HBsAg variants can lead to ER-derived oxidative stress and liver cell death in HuH-7 cells.
基金supported by the Natural Science Foundation of Shandong Province of China,No.ZR2014HM046(to ZCZ)
文摘Amyloid beta（Aβ）-induced oxidative stress is a major pathologic hallmark of Alzheimer＇s disease. Cyanidin, a natural flavonoid compound, is neuroprotective against oxidative damage-mediated degeneration. However, its molecular mechanism remains unclear. Here, we investigated the effects of cyanidin pretreatment against Aβ-induced neurotoxicity in PC12 cells, and explored the underlying mechanisms. Cyanidin pretreatment significantly attenuated Aβ-induced cell mortality and morphological changes in PC12 cells. Mechanistically, cyanidin effectively blocked apoptosis induced by Aβ, by restoring the mitochondrial membrane potential via upregulation of Bcl-2 protein expression. Moreover, cyanidin markedly protected PC12 cells from Aβ-induced DNA damage by blocking reactive oxide species and superoxide accumulation. These results provide evidence that cyanidin suppresses Aβ-induced cytotoxicity, by preventing oxidative damage mediated by reactive oxide species, which in turn inhibits mitochondrial apoptosis. Our study demonstrates the therapeutic potential of cyanidin in the prevention of oxidative stress-mediated Aβ neurotoxicity.
文摘With continuous population and economic growth in the 21st century,plastic pollution is a major global issue.However,the health concern of microplastics/nanoplastics(MPs/NPs)decomposed from plastic wastes has drawn public attention only in the recent decade.This article summarizes recent works dedicated to understanding the impact of MPs/NPs on the liver-the largest digestive organ,which is one of the primary routes that MPs/NPs enter human bodies.The interrelated mechanisms including oxidative stress,hepatocyte energy re-distribution,cell death and autophagy,as well as immune responses and inflammation,were also featured.In addition,the disturbance of microbiome and gut-liver axis,and the association with clinical diseases such as metabolic dysfunction-associated fatty liver disease,steatohepatitis,liver fibrosis,and cirrhosis were briefly discussed.Finally,we discussed potential directions in regard to this trending topic,highlighted current challenges in research,and proposed possible solutions.
文摘This study was aimed at evaluating the anti-diabetic potential of passion fruit Passiflora edulis(EPE) extracts in diabetic rats, following Streptozotocin(STZ) induced oxidative stress. Thirty adult Wistar rats were divided into five groups, with six rats in each group. The control rats were injected intraperitoneally with citrate buffer(pH 4.5). The remaining groups of rats were administered single dose of 45 mg·kg-1 of STZ by intraperitoneal route to induce diabetes. The diabetic animals were treated with 250 and 500 mg·kg-1 of EPE and glibenclamide 0.6 mg·kg-1 for fifteen days by oral route. Blood glucose, end organ oxidative stress marker, and anti-oxidants were assayed. Further, histopathological investigation of pancreas was studied at the end of the experimentation. The results revealed that subacute administration of EPE significantly(P < 0.001) controlled the blood glucose level in the diabetic rats. In addition, EPE extract protected the end organs by restoring the anti-oxidants enzyme, significantly increasing super oxide dismutase level(SOD) and decreasing catalase(CAT) and TBARS level in visceral organs. In conclusion, that EPE extracts showed anti-diabetic and anti-oxidant potential against streptozotocin-induced diabetes.
基金supported by the Ministry of Science and Technology of China(Nos.2016YFA0203102,2016YFC0900301 and 2014CB932003)the National Natural Science Foundation of China(Nos.21375142,21321004,and 21435008)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB14030000)
文摘Halobenzoquinones（HBQs） are an emerging class of halogenated disinfection byproducts（DBPs） in drinking water, which raised public concerns due to potential carcinogenic effects to human bladder. Our previous work demonstrated that HBQs and hydrogen peroxide（H_2O_2）together generated oxidative DNA damage via a metal-independent and intercalationenhanced oxidation mechanism in vitro. This study further investigated the efficiency of various HBQs to induce oxidative DNA damage in T24 bladder cancer cells. Compared with T24 cells without treatment（3.1 lesions per 10~6 d G）, the level of 8-oxo-7,8-dihydro-2′-deoxyguanosine（8-oxod G） significantly increased by 1.4, 3.2, 8.8, and 9.2 times after treatment with tetrabromo-1,4-benzoquinone（TBBQ）, terachloro-1,4-benzoquinone（TCBQ）,2,6-dichloro-1,4-benzoquinone（2,6-DCBQ） and 2,5-dichloro-1,4-benzoquinone（2,5-DCBQ） for24 hr, respectively. Interestingly, we found that the oxidative potency of HBQs in T24 cells（2,5-DCBQ ≈ 2,6-DCBQ 〉 TCBQ 〉 TBBQ） is inconsistent with that of in vitro ds DNA oxidation（TCBQ 〉 TBBQ 〉 2,5-DCBQ 〉 2,6-DCBQ）, suggesting HBQs induce oxidative lesions in cellular genomic DNA probably involved with a complex mechanism.
基金This work was supported by the Fundamental Research Funds for the Central Universities(2572018BW02)the Innovation Project of State Key Laboratory of Tree Genetics and Breeding(2016C01)+1 种基金the National Key R&D Program of China(2017YFD0600600)the National Natural Science Foundation of China(31400535 and 31570596).
文摘Programmed cell death occurs in browning explants of Fraxinus mandshurica during somatic embryogenesis, but the underlying mechanism is unclear. In this study, single cotyledons of zygotic embryos of F. mandshurica were used as explants. Mitochondrial structure and function, caspase-3-like protease activity, hydrogen peroxide metabolism, and nitric oxide accumulation induced by high concentrations of sucrose and plant growth regulators were studied. The results show that plant growth regulators induced somatic embryogenesis and also promoted explant browning. High sucrose concentrations had similar effects. High concentrations of sucrose and plant growth regulators led to the accumulation of hydrogen peroxide and nitric oxide which induced changes in mitochondrial structure and function such as modifications in mitochondrial morphology, increased membrane permeability, decreased membrane potential, and the release of cytochrome c into the cytoplasm. An increase in caspase-3-like protease activity triggered programmed cell death in some browning explant cells. During somatic embryogenesis there were increased activities of superoxide dismutase, peroxidase, and catalase, which are associated with hydrogen peroxide metabolism and jointly maintain reactive oxygen species levels. Intracellular nitric oxide synthase and nitrate reductase activities were not significantly correlated with nitric oxide content. Instead, intracellular nitric oxide may be derived from non-enzymatic reactions. Our results indicate that hydrogen peroxide and nitric oxide may function as signals, playing key roles in somatic embryogenesis and programmed cell death of explant cells of F. mandshurica. The interaction between nitric oxide and reactive oxygen species determines the occurrence of programmed cell death in explant cells;somatic embryogenesis and programmed cell death are positively regulated by hydrogen peroxide. However, the regulation of nitric oxide is complex.
基金This work was supported by the National Natural Science Foundation of China(Nos.U20A20133,21777187)the Royal Society International Collaboration Award for Research Professors(No.IC160121).
文摘Per-and polyfluoroalkyl substances(PFAS)are found to have multiple adverse outcomes on human health.Recently,epidemiological and toxicological studies showed that exposure to PFAS had adverse impacts on pancreas and showed association with insulin abnormalities.To explore how PFAS may contribute to diabetes,we studied impacts of perfluorooctane sul-fonate(PFOS)on cell viability and insulin release capacity of pancreatic β cells by using in vivo and in vitro methods.We found that 28-day administration with PFOS(10 mg/(kg body weight·day))caused reductions of pancreas weight and islet size in male mice.PFOS admin-istration also led to lower serum insulin level both in fasting state and after glucose infusion among male mice.For cell-based in vitro bioassay,we used mouse β-TC-6 cancer cells and found 48-hr exposure to PFOS decreased the cell viability at 50 μmol/L.By measuring insulin content in supernatant,48-hr pretreatment of PFOS(100 μmol/L)decreased the insulin re-lease capacity of β-TC-6 cells after glucose stimulation.Although these concentrations were higher than the environmental concentration of PFOS,it might be reasonable for high con-centration of PFOS to exert observable toxic effects in mice considering mice had a faster removal efficiency of PFOS than human.PFOS exposure(50 μmol/L)to β-TC-6 cells induced intracellular accumulation of reactive oxidative specie(ROS).Excessive ROS induced the re-active toxicity of cells,which eventually invoke apoptosis and necrosis.Results in this study provide evidence for the possible causal link of exposure to PFOS and diabetes risk.
基金Supported by the Society Development Program of the Natural Science Foundation of Jiangsu Province in China (No.BS2002016)
文摘Heavy metal pollution has become a worldwide problem in aquaculture. We studied copper （Cu^2＋） accumulation and physiological responses of two red algae Gracilaria lemaneiformis and Gracilaria lichenoides from China under Cu^2＋ exposure of 0-500 μg/L in concentration. Compared with G. lemaneiformis, G. lichenoides was more capable in accumulating Cu^2＋, specifically, more Cu〉 on extracellular side （cell wall） than on intracellular side （cytoplasm） and in cell organelles （especially chloroplast, cell nucleus, mitochondria, and ribosome）. In addition, G. lichenoides contained more insoluble polysaccharide in cell wall, which might promote the extracellular Cu^2＋-binding as an efficient barrier against metal toxicity. Conversely, G. lemaneiformis was more vulnerable than G. lichenoides to Cu^2＋ toxin for decreases in growth, pigment （chlorophyll a, chlorophyll b, phycobiliprotein, and B-carotene） content, and photosynthetic activity. Moreover, more serious oxidative damages in G. lemaneiformis than in G. lichenoides, in accumulation of reactive oxidative species and malondialdehyde, and in electrolyte leakage, because of lower antioxidant enzyme （superoxide dismutase and glutathione reductase） activities. Therefore, G. lichenoides was less susceptible to Cu〉 stress than G. lemaneiformis.
基金supported by the Special Research Foundation of Doctoral Course in Colleges and Universities of China in 2013,No.20133420110009
文摘Postoperative cognitive dysfunction is a crucial public health issue that has been increasingly studied in efforts to reduce symptoms or prevent its occurrence. However, effective advances remain lacking. Hyperbaric oxygen preconditioning has proved to protect vital organs, such as the heart, liver, and brain. Recently, it has been introduced and widely studied in the prevention of postoperative cognitive dysfunction, with promising results. However, the neuroprotective mechanisms underlying this phenomenon remain controversial. This review summarizes and highlights the definition and application of hyperbaric oxygen preconditioning, the perniciousness and pathogenetic mechanism underlying postoperative cognitive dysfunction, and the effects that hyperbaric oxygen preconditioning has on postoperative cognitive dysfunction. Finally, we conclude that hyperbaric oxygen preconditioning is an effective and feasible method to prevent, alleviate, and improve postoperative cognitive dysfunction, and that its mechanism of action is very complex, involving the stimulation of endogenous antioxidant and anti-inflammation defense systems.
基金supported by grants from the National Basic Research Development Program of the Ministry of Science and Technology of China (2009CB941301)Roche Research Grant, Peking University President Research Grant and the Recruiting Research Grant, Ministry of Education of China
文摘Objective To investigate whether intracellular amyloid β （iAβ） induces toxicity in wild type （WT） and APP/PS1 mice, a mouse model of Alzheimer＇s disease. Methods Different forms of Aβ aggregates were microinjected into cultured WT or APP/PS1 mouse hippocampal neurons. TUNEL staining was performed to examine neuronal cell death. Reactive oxidative species （ROS） were measured by MitoSOXTM Red mitochondrial superoxide indicator. Results Crude, monomer and protofibrilAβ induced more toxicity inAPP/PS1 neurons than in WT neurons. ROS are involved in mediating the vulnerability of APP/PS1 neurons to iAβ toxicity. Conclusion Oxidative stress may mediate cell death induced by iAβ in neurons.
