Decreased osteogenesis of adult mesenchymal stem cel s by reactive oxygen species under cyclic stretch: a possible mechanism of age related osteoporosis

Age related defect of the osteogenic differentiation of mesenchymal stem cells（MSCs） plays a key role in osteoporosis. Mechanical loading is one of the most important physical stimuli for osteoblast differentiation.Here, we compared the osteogenic potential of MSCs from young and adult rats under three rounds of 2 h of cyclic stretch of 2.5% elongation at 1 Hz on 3 consecutive days. Cyclic stretch induced a significant osteogenic differentiation of MSCs from young rats, while a compromised osteogenesis in MSCs from the adult rats.Accordingly, there were much more reactive oxygen species（ROS） production in adult MSCs under cyclic stretch compared to young MSCs. Moreover, ROS scavenger N-acetylcysteine rescued the osteogenic differentiation of adult MSCs under cyclic stretch. Gene expression analysis revealed that superoxide dismutase 1（SOD1） was significantly downregulated in those MSCs from adult rats. In summary, our data suggest that reduced SOD1 may result in excessive ROS production in adult MSCs under cyclic stretch, and thus manipulation of the MSCs from the adult donors with antioxidant would improve their osteogenic ability.

Effects of Selenium Dioxide on Apoptosis, Bcl-2 and P53 Expression, Intracellular Reactive Oxygen Species and Calcium Level in Three Human Lung Cancer Cell Lines

To evaluate the anti-tumor effects of SeO2 and its mechanisms on three human lung cancer cell lines. Methods: Three lung cancer cells A549, GLC-82 and PG were treated with 3-30 μmol/L SeO2. Flow cytometry was used to detect apoptosis, and analyze the changes of expression of p53 and Bcl-2, as well as ROS and Ca^2+ level within cells. Results:SeO2 markedly inhibited cell proliferation and viability, and prompted apoptosis after 48 h treatment. SeO2 at 10 μmol/L induced 47.8% apoptosis in A549 cells, 40.8% in GLC-82 cells, 18.2% in PG cells. SeO2 at 30 μmol/L induced 37.8% apoposis in PG cells,but did not increase apoptotic raes in other two cells. SeO2 could down-regulate the mean fluorescent intensity of Bcl-2 from 65.8 to 9.6 in A549, but not in GLC-82 and in PG, cells, up-regulate wild type p53 level in all three cells. SeO2 decreased the ROS and Ca^2+ level markedly within three tested cells. Conclusion: SeO2 showed anti-tumor effect via apoptosis pathway in three lung cancer cell lines. The decrease of ROS and Ca^2+ level within cells as well as regulation of Bcl-2 and p53 expression may play important roles in above apoptotic procedure.

Cell metabolism pathways involved in the pathophysiological changes of diabetic peripheral neuropathy

Diabetic peripheral neuropathy is a common complication of diabetes mellitus.Elucidating the pathophysiological metabolic mechanism impels the generation of ideal therapies.However,existing limited treatments for diabetic peripheral neuropathy expose the urgent need for cell metabolism research.Given the lack of comprehensive understanding of energy metabolism changes and related signaling pathways in diabetic peripheral neuropathy,it is essential to explore energy changes and metabolic changes in diabetic peripheral neuropathy to develop suitable treatment methods.This review summarizes the pathophysiological mechanism of diabetic peripheral neuropathy from the perspective of cellular metabolism and the specific interventions for different metabolic pathways to develop effective treatment methods.Various metabolic mechanisms(e.g.,polyol,hexosamine,protein kinase C pathway)are associated with diabetic peripheral neuropathy,and researchers are looking for more effective treatments through these pathways.

The cell cycle related apoptotic susceptibility to arsenic trioxide is associated with the level of reactive oxygen species

Double staining flow cytometry was performed using 7-amino actinomycin D and 6-carboxy-2',7'-dichlorodihydrofluorescein diacetate,to detect the level fluctuation of reactive oxygen species (ROS) during the cell cycle of normal NB4 cells. Our results showed that NB4 cells possessed higher level of ROS in G2/M phase than in G1 and S phases. Double staining flow cytometry,with TdT mediated dUTP nick end labeling (Tunel) and propidium iodide (PI),indicated that As2O3 (2 μM) could induce apoptosis in NB4 cells prevailingly from G2/M phase,and this efficacy was enhanced upon co-administration of 2,3-dimethoxy-1,4-naphthoquinone (DMNQ) (2.5 μM) which could produce the endogenous ROS. These results suggested that different ROS level in different cell cycle phases of NB4 cells might determin the selective induction of G2/M apoptosis and the cells' susceptibility to apoptosis by As2O3.

TaNF-YB11,a gene of NF-Y transcription factor family in Triticum aestivum,confers drought tolerance on plants via modulating osmolyte accumulation and reactive oxygen species homeostasis

Transcription factors(TFs)regulate diverse stress defensive-associated physiological processes and plant stress responses.We characterized TaNF-YB11,a gene of the NF-YB TF family in Triticum aestivum,in mediating plant drought tolerance.TaNF-YB11 harbors the conserved domains specified by its NF-YB partners and targets the nucleus after the endoplasmic reticulum(ER)assortment.Yeast two-hybrid assay indicated the interactions of TaNF-YB11 with TaNF-YA2 and TaNF-YC3,two proteins encoded by genes in the NF-YA and NF-YC families,respectively.These results suggested that the heterotrimer established among them further regulated downstream genes at the transcriptional level.The transcripts of TaNF-YB11 were promoted in roots and leaves under a 27-h drought regime.Moreover,its upregulated expression levels under drought were gradually restored following a recovery treatment,suggesting its involvement in plant drought response.TaNF-YB11 conferred improved drought tolerance on plants;the lines overexpressing target gene displayed improved phenotype and biomass compared with wild type(WT)under drought treatments due to enhancement of stomata closing,osmolyte accumulation,and cellular reactive oxygen species(ROS)homeostasis.Knockdown expression of TaP5CS2,a P5CS family gene modulating proline biosynthesis that showed upregulated expression in drought-challenged TaNF-YB11 lines,alleviated proline accumulation of plants treated by drought.Likewise,TaSOD2 and TaCAT3,two genes encoding superoxide dismutase(SOD)and catalase(CAT)that were upregulated underlying TaNF-YB11 regulation,played critical roles in ROS homeostasis via regulating SOD and CAT activities.RNA-seq analysis revealed that numerous genes associated with processes of‘cellular processes',‘environmental information processing',‘genetic information processing',‘metabolism',and‘organismal systems'modified transcription under drought underlying control of TaNF-YB11.These results suggested that the TaNF-YB11-mediated drought response is possibly accomplished through the target gene in modifying gene transcription at the global level,which modulates complicated biological processes related to drought response.TaNF-YB11 is essential in plant drought adaptation and a valuable target for molecular breeding of drought-tolerant cultivars in T.aestivum.

Overproduction of reactive oxygen species–obligatory or not for induction of apoptosis by anticancer drugs

Many studies demonstrate that conventional anticancer drugs elevate intracellular level of reactive oxygen species （ROS） and alter redox-homeostasis of cancer cells. It is widely accepted that anticancer effect of these chemotherapeutics is due to induction of oxidative stress and ROS-mediated apoptosis in cancer. On the other hand, the harmful side effects of conventional anticancer chemotherapy are also due to increased production of ROS and disruption of redox-homeostasis of normal cells and tissues. This article describes the mechanisms for triggering and modulation of apoptosis through ROS-dependent and ROS^independent pathways. We try to answer the question： ＂Is it possible to induce highly specific apoptosis only in cancer cells, without overproduction of ROS, as well as without harmful effects on normal cells and tissues？＂ The review also suggests a new therapeutic strategy for selective killing of cancer cells, without significant impact on viability of normal cells and tissues, by combining anticancer drugs with redox-modulators, affecting specific signaling pathways and avoiding oxidative stress.

Effect of dietary supplementation of vitamin C on growth, reactive oxygen species, and antioxidant enzyme activity of Apostichopus japonicus(Selenka) juveniles exposed to nitrite

Different amounts of vitamin C were added to diets fed to juveniles(2.5 ± 0.15 g) of sea cucumber Apostichopus japonic u s(Selenka) in an attempt to reduce the stress response of specimens exposed to nitrite stress. A commercial feed was used as the control diet and three experimental diets were made by supplementing 1 000, 1 500, or 2 000 mg vitamin C/kg diet to control diet separately in a 45-day experiment. Sea cucumbers were exposed to three different levels(0.5, 1.0, and 1.5 mg/L) of nitrite stress for 4, 8, and 12 h at four time intervals(0, 15, 30, and 45 d). Growth of the animals was recorded during the experiment. Reactive oxygen species(ROS)(i.e. hydroxyl free radical(-OH), malondialdehyde(MDA) and total antioxidant capacity(T-AOC)) and antioxidant enzyme activities(i.e., superoxide dismutase(SOD) and catalase(CAT)) were measured. Response surface methodology(RSM) was used to analyze the effect of multiple factors on ROS indices and enzyme activities. Weight gain(WG) and special growth rate(SGR) of vitamin C supplementation groups were significantly higher than those of control group( P< 0.05). The levels of-OH and MDA increased under exposure time extending and nitrite concentration increasing, whereas T-AOC level decreased. SOD and CAT activities increased at 4 h and 8 h and decreased at 12 h. During the days in which the animal consumed experimental diets, the levels of-OH and MDA decreased and that of T-AOC increased. This result suggests that diets containing vitamin C could reduce the nitrite stress response in the animals and increase their antioxidant capacity. The multifactor regression equation of growth performance, ROS indices, and duration of feeding results suggest that vitamin C supplementation of 1 400–2 000 mg/kg diet for 29–35 days could reduce effectively the effects of nitrite exposure.

亚硒酸钠通过增加ROS抑制PI3K/AKT通路改善肺癌PC-9/GR细胞对吉非替尼的耐药性

目的:探讨亚硒酸钠对肺癌耐药细胞PC-9/GR增殖、凋亡的影响,研究其是否能改善吉非替尼耐药及可能机制。方法:不同浓度(0、5、10、20、40μmol/L)亚硒酸钠处理细胞24、36、48 h后,CCK-8法检测亚硒酸钠对细胞增殖的影响并选择合适浓度用于后续实验。不同浓度(0、2.5、5、10、20、40μmol/L)吉非替尼单药及联合亚硒酸钠(6μmol/L)处理细胞48 h,分别计算半数抑制浓度(IC50),得出亚硒酸钠对PC-9/GR逆转倍数;流式细胞术检测各组细胞凋亡;DCFH-DA法检测细胞内ROS水平;Western blot实验检测各组细胞中p-PI3K、p-AKT、Bax、Bcl-2表达水平。结果:随亚硒酸钠浓度升高及作用时间延长,细胞增殖抑制率逐渐升高(P<0.05);单药吉非替尼组的IC50值为16.051μmol/L,联合亚硒酸钠后IC50值为5.406μmol/L,表明亚硒酸钠能够逆转吉非替尼的耐药,其逆转耐药倍数为2.969倍。与吉非替尼和亚硒酸钠单药组相比,联合治疗组的细胞凋亡率显著升高,ROS水平及Bax蛋白表达上调,p-PI3K、p-AKT、Bcl-2表达下调,经N-乙酰半胱氨酸(NAC)消除ROS后抵消了亚硒酸钠对PI3K/AKT通路的抑制作用(P<0.05)。结论:亚硒酸钠联合吉非替尼能提高肺腺癌耐药细胞的敏感性,抑制细胞的增殖,同时诱导细胞凋亡,这一过程可能通过ROS依赖性下调PI3K/AKT通路的表达实现。

ROS Balance Autoregulating Core-Shell CeO_(2)@ZIF-8/Au Nanoplatform for Wound Repair

Reactive oxygen species(ROS)plays important roles in living organisms.While ROS is a double-edged sword,which can eliminate drug-resistant bacteria,but excessive levels can cause oxidative damage to cells.A core–shell nanozyme,Ce O_(2)@ZIF-8/Au,has been crafted,spontaneously activating both ROS generating and scavenging functions,achieving the multifaceted functions of eliminating bacteria,reducing inflammation,and promoting wound healing.The Au Nanoparticles(NPs)on the shell exhibit high-efficiency peroxidase-like activity,producing ROS to kill bacteria.Meanwhile,the encapsulation of Ce O_(2) core within ZIF-8 provides a seal for temporarily limiting the superoxide dismutase and catalase-like activities of Ce O_(2) nanoparticles.Subsequently,as the ZIF-8 structure decomposes in the acidic microenvironment,the Ce O_(2) core is gradually released,exerting its ROS scavenging activity to eliminate excess ROS produced by the Au NPs.These two functions automatically and continuously regulate the balance of ROS levels,ultimately achieving the function of killing bacteria,reducing inflammation,and promoting wound healing.Such innovative ROS spontaneous regulators hold immense potential for revolutionizing the field of antibacterial agents and therapies.

Disinfection Kinetics and Contribution of Reactive Oxygen Species When Eliminating Bacteria with TiO_(2) Induced Photocatalysis

Titania (TiO2) induced photocatalysis has been widely investigated and applied as a disinfection strategy in many industrial and clinical applications. Reactive oxygen species (ROS), including hydroxyl radicals (&8226OH), superoxide radicals () and hydrogen peroxide (H2O2), generated in the photocatalytic reaction process are considered to be the active components prompting the bactericidal effect. In the present work, the kinetics of photocatalytic inactivation of Staphylococcus epidermidis and specific contributions of &#8226OH, and H2O2 to the bactericidal process were studied using two disinfection settings sutilizing photocatalytic resin-TiO2 nanocomposite surfaces and suspended TiO2 nanoparticles, respectively. In antibacterial tests against S. epidermidis with a layer of bacterial suspension on the resin-TiO2 surfaces, H2O2 was found to be the most efficient ROS component contributing to the antibacterial effect. Disinfection kinetics showed a two-step behavior with an initial region having a lower disinfection rate followed by a higher rate region after 10 min of UV irradiation. By contrast, in antibacterial tests with suspended bacteria and photocatalytic TiO2 nanoparticles, &#8226OH and H2O2 showed equal significance in the bacterial inactivation having a typical Chick-Watson disinfection kinetics behavior with a steady disinfection rate. The results contribute to the understanding of the bactericidal mechanism and kinetics of photocatalytic disinfection that are essential for designing specific antibacterial applications of photocatalytic materials.

Regulating Signal Pathway Triggers Circular Reactive Oxygen Species Production to Augment Oxidative Stress with Enzyme-Activated Nanoparticles

Regulating antioxidative stress pathways to augment oxidative stress and enhance antitumor therapy is highly desirable but very challenging.Herein,we initiated a multifunctional nanoparticle to regulate the Keap1-Nrf2 antioxidative stress pathway to promote cancer cell apoptosis.The OPFV-SnMP@GE11 nanoparticles were assembled by enzyme-activated OPFV-TLQ,tin mesoporphyrin(SnMP),and DSPEPEG-GE11.OPFV-SnMP@GE11 accumulated at tumor sites through specific targeting with GE11.OPFV-TLQ was specifically reduced to a photosensitizer OPFVNH2 by endocellular NAD(P)H:quinone oxidoreductase 1(NQO1).Under irradiation,OPFV-NH2 greatly produced reactive oxygen species(ROS)through a type I mechanism,which activated the Keap1-Nrf2 signal pathway and enhanced the transcription of NQO1,resulting in a continuous and explosive generation of ROS.Additionally,SnMP inhibited the activity of heme oxygenase-1(HO-1),further depressing antioxidative stress.This strategy provides insight into the regulation of the signal pathway to amplify oxidative stress,paving the way to studying the molecular mechanisms of cellular activities to enhance cancer therapy.

Dichloroacetic Acid (DCA)-Induced Cytotoxicity in Human Breast Cancer Cells Accompanies Changes in Mitochondrial Membrane Permeability and Production of Reactive Oxygen Species

Cancer cells utilize cytosolic glycolysis for their energy production even in the presence of adequate levels of oxygen (Warbug effect) due to mitochondrial defects. Dichloroacetic acid (DCA) shifts cytosolic glucose metabolism to aerobic oxidation by inhibiting mitochondrial pyruvate dehydrogenase kinase (PDK) and increasing pyruvate uptake. Therefore, DCA has potential in reversing the glycolytic metabolism defect in cancerous cells. DCA is also known to induce apoptosis in a number of cancer cell lines, the mechanism of which is not well understood. In this study, an attempt has been made to investigate the effects of DCA on aggressive human breast cancer (MCF-7) cells as compared with less aggressive mouse osteoblastic (MC3T3) cells. Cell cytotoxicity was determined by MTT, crystal violet and Trypan blue exclusion assays. Western blot was used to detect any changes in the expression of apoptotic markers. Flow cytometry was used to measure apoptotic and necrotic effects of DCA. Mitochondrial integrity was determined by change in mitochondrial membrane potential (Δψm), whereas oxidative damage was determined by production of reactive oxygen species (ROS). DCA caused a concentration-dependent cytotoxicity both in MCF-7 and MC3T3 cell lines. MCF-7 cells were most affected. Flow cytometry results showed a significantly higher apoptosis in MCF-7 even at lower concentrations of DCA. However, higher concentrations of DCA were necrotic. Western blotting showed an increased expression of Mn-SOD-1 upon DCA treatment. Further, DCA decreased Δψm and increased ROS production. The effects of DCA were more pronounced on MCF-7 cells as compared to MC3T3 cells. Our results suggest that DCA-induced cytotoxicity in cancerous cells is mediated via changes in Δψm and production of ROS.

橙皮苷抑制ROS/NLRP3通路改善小鼠急性支气管炎的作用机制研究

目的从活性氧簇(ROS)/NOD样受体家族蛋白3(NLRP3)通路,探讨橙皮苷对急性支气管炎小鼠支气管组织损伤的影响及相关作用机制。方法取C57BL/6小鼠100只,用随机数字表法分为正常对照组、模型组、橙皮苷组(36 mg·kg^(-1),灌胃)、ROS/NLRP3通路激活剂(三甲胺N-氧化物)组、橙皮苷+三甲胺N-氧化物组,每组20只;用香烟暴露法制备模型,末次给药后观察小鼠一般行为,检测肺泡灌洗液中炎症细胞数量及炎症因子白细胞介素1β(IL-1β)、白细胞介素18(IL-18)水平,肺组织中氧化应激产物髓过氧化物酶(MPO)、丙二醛(MDA)水平;氨水引咳法测咳嗽潜伏期及咳嗽次数;取支气管肺组织,HE染色法测组织病理变化;流式细胞仪测ROS含量;免疫组化法测NLRP3阳性表达水平;Western Blot法测IL-1β、IL-18、超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、硫氧还蛋白结合蛋白(TXNIP)、凋亡相关斑点样蛋白(ASC)、凋亡前体蛋白(pro-Caspase-1)、半胱天冬酶-1(Caspase-1)水平。结果与正常对照组比,模型组小鼠咳嗽症状加重,支气管肺泡灌洗液中炎症细胞数目及炎症因子水平升高,支气管肺组织炎症反应及氧化应激加重,ROS/NLRP3通路及其相关蛋白表达升高(P<0.05)。橙皮苷可抑制ROS/NLRP3通路及其相关蛋白表达,缓解小鼠咳嗽症状,减轻炎症及氧化应激反应(P<0.05)。ROS/NLRP3通路激活剂-三甲胺N-氧化物可逆转橙皮苷上述作用(P<0.05)。结论橙皮苷可能通过抑制ROS/NLRP3通路活化,改善急性支气管炎小鼠支气管肺组织炎症及氧化应激损伤,缓解咳嗽症状。

Low-temperature Plasma Promotes Fibroblast Proliferation in Wound Healing by ROS-activated NF-κB Signaling Pathway

Low-temperature plasma（LTP） has shown great promise in wound healing,although the underlying mechanism remains poorly understood.In the present study,an argon atmospheric pressure plasma jet was employed to treat L929 murine fibroblasts cultured in vitro and skin wounds in BALB/c mice.The in vitro analysis revealed that treatment of fibroblasts with LTP for 15 s resulted in a significant increase in cell proliferation,secretion of epidermal growth factor（EGF） and transforming growth factor-β1（TGF-β1）,production of intracellular reactive oxygen species（ROS）,and the percentage of cells in S phase,protein expression of phosphorylated p65（P-p65） and cyclin D1,but a noted decrease in the protein expression of inhibitor kappa B（IκB）.The in vivo experiments demonstrated that 30-s LTP treatment enhanced the number of fibroblasts and the ability of collagen synthesis,while 50-s treatment led to the opposite outcomes.These results suggested that LTP treatment promotes the fibroblast proliferation in wound healing by inducing the generation of ROS,upregulating the expression of P-p65,downregulating the expression of IκB,and activating the NF-κB signaling pathway and consequently altering cell cycle progression（increased DNA synthesis in S phage）.

益气活血托毒方对慢性非细菌性前列腺炎大鼠ROS、GSH-Px、MDA的影响

目的:观察益气活血托毒方对慢性非细菌性前列腺炎大鼠活性氧(ROS)、谷胱甘肽过氧化物酶(GSH-Px)、丙二醛(MDA)的影响,探究益气活血托毒方治疗慢性非细菌性前列腺炎的作用机制。方法:选用48只SPF级健康SD雄性大鼠,随机分为空白组、模型组、塞来昔布组、益气活血托毒方组,每组12只。通过切除睾丸结合雌激素诱导制备慢性非细菌性前列腺炎模型大鼠,造模成功后给予各组大鼠相应药物干预,连续给药4周后处死,取前列腺组织。记录前列腺质量计算前列腺指数,采用HE染色观察前列腺组织病理变化,化学荧光法检测ROS浓度,比色法测定超氧化物歧化酶(SOD)、GSH-Px、MDA水平。结果:空白组大鼠前列腺组织结构完整、间质未见扩张和炎症细胞浸润;模型组大鼠前列腺组织结构破坏明显、间质水肿、炎症细胞弥漫性浸润;与模型组比较,益气活血托毒方组、塞来昔布组大鼠前列腺组织结构及间质水肿不同程度恢复且炎症细胞浸润减轻。模型组大鼠前列腺指数低于空白组(P<0.01);益气活血托毒方组、塞来昔布组大鼠前列腺指数与模型组比较,差异无统计学意义(P>0.05)。模型组大鼠血清ROS、MDA水平高于空白组(P<0.01),血清SOD、GSH-Px水平低于空白组(P<0.01);益气活血托毒方组、塞来昔布组大鼠血清ROS、MDA水平均低于模型组(P<0.01),血清GSH-Px水平均高于模型组(P<0.01);塞来昔布组大鼠血清SOD水平高于模型组(P<0.05);益气活血托毒方组大鼠血清SOD水平与模型组比较,差异无统计学意义(P>0.05)。结论:益气活血托毒方能改善慢性非细菌性前列腺炎模型大鼠前列腺病理结构,降低ROS、MDA水平,升高GSH-Px水平,改善氧化应激状态,恢复前列腺组织功能。

Effect of Foliar GA_(3) and ABA Applications on Reactive Oxygen Metabolism in Black Currants (Ribes nigrum L.) During Bud Para-dormancy and Secondary Bud Burst

The secondary bud burst can cause around 10%-20%yield losses in black currants,an economically important crop in parts of Europe,Asia and North America.The metabolism of reactive oxygen species(ROS)has been linked to bud dormancy and its early release(secondary bud burst)in several fruit crops.But the relationship between ROS metabolism and the secondary bud burst is still not well understood in black currants.In the present study,two black currant cultivars(Adelinia and Heifeng)with opposing tendency of exhibiting the secondary bud burst were sprayed with abscisic acid(ABA)and gibberellic acid(GA_(3))to either inhibit or induce the secondary bud burst.The results showed that ABA inhibited the secondary bud burst by reducing the contents of ROS(H_(2)O_(2),O_(2)-·)in buds;decreasing the activities of superoxide dismutase(SOD),peroxidase(POD)and catalase(CAT);and increasing the contents of oxidized glutathione(GSSG)and ascorbic acid(AsA).GA_(3) effectively induced the secondary bud burst by increasing ROS contents;increasing the activities of several antioxidant enzymes,such as SOD,POD,CAT,glutathione reductase(GR),ascorbate peroxidase(APX)and the contents of reduced glutathione(GSH);and decreasing the contents of AsA.The experimental results showed that GA_(3) treatment increased the content of ROS,accelerated the metabolism of reactive oxygen species,and promoted the second burst of black currants.However,ROS metabolism was at a low level under ABA treatment,and the buds remained dormant.These results suggested that ROS metabolism might play an important role in the two black currants of the secondary bud burst.

Impact of Beijing’s“Coal to Electricity”program on ambient PM_(2.5) and the associated reactive oxygen species(ROS)

The Beijing“Coal to Electricity”program provides a unique opportunity to explore air quality impacts by replacing residential coal burning with electrical appliances.In this study,the atmospheric ROS(Gas-phase ROS and Particle-phase ROS,abbreviated to G-ROS and P-ROS)were measured by an online instrument in parallel with concurrent PM_(2.5) sample collections analyzed for chemical composition and cellular ROS in a baseline year(Coal Use Year-CUY)and the first year following implementation of the“Coal to Electricity”program(Coal Ban Year-CBY).The results showed PM_(2.5) concentrations had no significant difference between the two sampling periods,but the activities of G-ROS,P-ROS,and cellular ROS in CBY were 8.72 nmol H_(2)O_(2)/m^(3),9.82 nmol H 2 O 2/m 3,and 2045.75μg UD/mg PM higher than in CUY.Six sources were identified by factor-analysis from the chemical components of PM_(2.5).Secondary sources(SECs)were the dominant source of PM_(2.5) in the two periods,with 15.90%higher contribution in CBY than in CUY.Industrial Emission&Coal Combustion sources(Ind.&CCs),mainly from regional transport,also increased significantly in CBY.The contributions of Aged Sea Salt&Residential Burning sources to PM_(2.5) decreased 5.31% from CUY to CBY.The correlation results illustrated that Ind.&CCs had significant positive correlations with atmospheric ROS,and SECs significantly associated with cellular ROS,especially nitrates(r=0.626,p=0.000).Therefore,the implementation of the“Coal to Electricity”program reduced PM_(2.5) contributions from coal and biomass combustion,but had little effect on the improvement of atmospheric and cellular ROS.

Anti-diabetic potential of apigenin,luteolin,and baicalein via partially activating PI3K/Akt/GLUT-4 signaling pathways in insulin-resistant HepG2 cells

Dietary flavonoids are abundant in natural plants and possess multiple pharmacological and nutritional activities.In this study,apigenin,luteolin,and baicalein were chosen to evaluate their anti-diabetic effect in high-glucose and dexamethasone induced insulin-resistant(IR)HepG2 cells.All flavonoids improves the glucose consumption and glycogen synthesis abilities in IR-HepG2 cells via activating glucose transporter protein 4(GLUT4)and phosphor-glycogen synthase kinase(GSK-3β).These fl avonoids signifi cantly inhibited the production of reactive oxygen species(ROS)and advanced glycation end-products(AGEs),which were closely related to the suppression of the phosphorylation form of NF-κB and P65.The expression levels of insulin receptor substrate-1(IRS-1),insulin receptor substrate-2(IRS-2)and phosphatidylinositol 3-kinase(PI3K)/protein kinase B(Akt)pathway in IR-HepG2 cells were all partially activated by the fl avonoids,with variable effects.Furthermore,the intracellular metabolic conditions of the fl avonoids were also evaluated.

锰超氧化物歧化酶的催化原理与酶活性调节机制

锰超氧化物歧化酶(MnSOD)催化两分子超氧自由基歧化为分子氧和过氧化氢。超氧自由基被Mn~(3+)SOD氧化成分子氧的反应以扩散的方式进行。超氧自由基被Mn~(2+)SOD还原为过氧化氢的反应以快循环和慢循环两条途径平行进行。在慢循环途径中,Mn~(2+)SOD与超氧自由基形成产物抑制复合物,然后该复合物被质子化而缓慢释放出过氧化氢。在快循环途径中,超氧自由基直接被Mn~(2+)SOD转化为产物过氧化氢,快速循环有利于酶的复活与周转。本文提出温度是调节锰超氧化物歧化酶进入慢速或者快速循环催化途径的关键因素。随着在生理温度范围内的温度升高,慢速循环成为整个催化反应的主流,因而生理范围内的温度升高反而抑制该酶的活性。锰超氧化物歧化酶的双相酶促动力学特性可以用该酶保守活性中心的温度依赖性配位模型进行合理化解释。当温度降低时,1个水分子(或者OH~-)接近Mn、甚至与Mn形成配位键,从而干扰超氧自由基与Mn形成配位键而避免形成产物抑制。因此在低温下该酶促反应主要在快循环通路中进行。最后阐述了几种化学修饰模式对该酶的调节,说明锰超氧化物歧化酶受到多种形式的快速调节(变构调节与化学修饰)。这些快速调节直接改变酶的活化状态,进而调节细胞中超氧自由基和过氧化氢的平衡与流量,为揭示锰超氧化物歧化酶和超氧自由基的生理作用提供新理论。

银耳多糖对人软骨细胞的增殖效应和抗炎作用

目的:骨关节炎(Osteoarthritis,OA)是一种常见的慢性关节性疾病,本研究旨在探究银耳多糖对骨关节炎细胞模型人软骨细胞T/C-28a2的增殖效应和抗炎作用。方法:通过MTT(3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide)和结晶紫染色实验检测银耳多糖对T/C-28a2细胞增殖活力和细胞毒性的影响;用脂多糖(Lipopolysaccharide,LPS)处理T/C-28a2细胞建立骨炎症模型,酶联免疫吸附测定(Enzyme-linked immunosorbent assay,ELISA)检测药物处理后细胞白介素-6(Interleukin-6,IL-6)的表达;利用蛋白免疫印迹(Western blot)检测药物处理后相关骨保护因子和炎症因子的表达;通过ROS活性氧释放实验检测药物对细胞的氧化应激水平和抗炎症反应。结果:银耳多糖能够促进人软骨细胞T/C-28a2的增殖活力,且没有明显的细胞毒性;使用LPS刺激软骨细胞模拟骨炎症的环境,药物处理后发现银耳多糖和硫酸软骨素处理能减少IL-6分泌从而抑制炎症发生;进一步Western blot检测发现银耳多糖刺激后,相关骨保护因子(Osteoprotegerin,OPG)的表达上调,而促凋亡相关蛋白Bax、细胞外信号调节激酶(Extracellular-signal-regulated kinases,ERK-MAPK)和核内转录因子κB(Nuclear factor-kappaB,NF-κB)的表达下调。活性氧(Reactive oxygen species,ROS)释放实验结果显示,银耳多糖和硫酸软骨素能够抑制细胞内ROS水平,抑制炎症反应的发生。结论:银耳多糖具有抑制骨关节炎的效用,可以在一定程度上保护软骨组织,抵抗细胞凋亡。本研究初步探讨了银耳多糖的抗炎作用及机制,为开发银耳多糖作为抗炎药物提供初步的实验依据。