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Sample records for extracellularly generated reactive

  1. Singlet oxygen treatment of tumor cells triggers extracellular singlet oxygen generation, catalase inactivation and reactivation of intercellular apoptosis-inducing signaling.

    PubMed

    Riethmüller, Michaela; Burger, Nils; Bauer, Georg

    2015-12-01

    Intracellular singlet oxygen generation in photofrin-loaded cells caused cell death without discrimination between nonmalignant and malignant cells. In contrast, extracellular singlet oxygen generation caused apoptosis induction selectively in tumor cells through singlet oxygen-mediated inactivation of tumor cell protective catalase and subsequent reactivation of intercellular ROS-mediated apoptosis signaling through the HOCl and the NO/peroxynitrite signaling pathway. Singlet oxygen generation by extracellular photofrin alone was, however, not sufficient for optimal direct inactivation of catalase, but needed to trigger the generation of cell-derived extracellular singlet oxygen through the interaction between H2O2 and peroxynitrite. Thereby, formation of peroxynitrous acid, generation of hydroxyl radicals and formation of perhydroxyl radicals (HO2(.)) through hydroxyl radical/H2O2 interaction seemed to be required as intermediate steps. This amplificatory mechanism led to the formation of singlet oxygen at a sufficiently high concentration for optimal inactivation of membrane-associated catalase. At low initial concentrations of singlet oxygen, an additional amplification step needed to be activated. It depended on singlet oxygen-dependent activation of the FAS receptor and caspase-8, followed by caspase-8-mediated enhancement of NOX activity. The biochemical mechanisms described here might be considered as promising principle for the development of novel approaches in tumor therapy that specifically direct membrane-associated catalase of tumor cells and thus utilize tumor cell-specific apoptosis-inducing ROS signaling. PMID:26225731

  2. Singlet oxygen treatment of tumor cells triggers extracellular singlet oxygen generation, catalase inactivation and reactivation of intercellular apoptosis-inducing signaling☆

    PubMed Central

    Riethmüller, Michaela; Burger, Nils; Bauer, Georg

    2015-01-01

    Intracellular singlet oxygen generation in photofrin-loaded cells caused cell death without discrimination between nonmalignant and malignant cells. In contrast, extracellular singlet oxygen generation caused apoptosis induction selectively in tumor cells through singlet oxygen-mediated inactivation of tumor cell protective catalase and subsequent reactivation of intercellular ROS-mediated apoptosis signaling through the HOCl and the NO/peroxynitrite signaling pathway. Singlet oxygen generation by extracellular photofrin alone was, however, not sufficient for optimal direct inactivation of catalase, but needed to trigger the generation of cell-derived extracellular singlet oxygen through the interaction between H2O2 and peroxynitrite. Thereby, formation of peroxynitrous acid, generation of hydroxyl radicals and formation of perhydroxyl radicals (HO2.) through hydroxyl radical/H2O2 interaction seemed to be required as intermediate steps. This amplificatory mechanism led to the formation of singlet oxygen at a sufficiently high concentration for optimal inactivation of membrane-associated catalase. At low initial concentrations of singlet oxygen, an additional amplification step needed to be activated. It depended on singlet oxygen-dependent activation of the FAS receptor and caspase-8, followed by caspase-8-mediated enhancement of NOX activity. The biochemical mechanisms described here might be considered as promising principle for the development of novel approaches in tumor therapy that specifically direct membrane-associated catalase of tumor cells and thus utilize tumor cell-specific apoptosis-inducing ROS signaling. PMID:26225731

  3. Enzymatic Production of Extracellular Reactive Oxygen Species by Marine Microorganisms

    NASA Astrophysics Data System (ADS)

    Diaz, J. M.; Andeer, P. F.; Hansel, C. M.

    2014-12-01

    Reactive oxygen species (ROS) serve as intermediates in a myriad of biogeochemically important processes, including cell signaling pathways, cellular oxidative stress responses, and the transformation of both nutrient and toxic metals such as iron and mercury. Abiotic reactions involving the photo-oxidation of organic matter were once considered the only important sources of ROS in the environment. However, the recent discovery of substantial biological ROS production in marine systems has fundamentally shifted this paradigm. Within the last few decades, marine phytoplankton, including diatoms of the genus Thalassiosira, were discovered to produce ample extracellular quantities of the ROS superoxide. Even more recently, we discovered widespread production of extracellular superoxide by phylogenetically and ecologically diverse heterotrophic bacteria at environmentally significant levels (up to 20 amol cell-1 hr-1), which has introduced the revolutionary potential for substantial "dark" cycling of ROS. Despite the profound biogeochemical importance of extracellular biogenic ROS, the cellular mechanisms underlying the production of this ROS have remained elusive. Through the development of a gel-based assay to identify extracellular ROS-producing proteins, we have recently found that enzymes typically involved in antioxidant activity also produce superoxide when molecular oxygen is the only available electron acceptor. For example, large (~3600 amino acids) heme peroxidases are involved in extracellular superoxide production by a bacterium within the widespread Roseobacter clade. In Thalassiosira spp., extracellular superoxide is produced by flavoproteins such as glutathione reductase and ferredoxin NADP+ reductase. Thus, extracellular ROS production may occur via secreted and/or cell surface enzymes that modulate between producing and degrading ROS depending on prevailing geochemical and/or ecological conditions.

  4. Reactive oxidants and myeloperoxidase and their involvement in neutrophil extracellular traps.

    PubMed

    Parker, Heather; Winterbourn, Christine C

    2012-01-01

    Neutrophils release extracellular traps (NETs) in response to a variety of inflammatory stimuli. These structures are composed of a network of chromatin strands associated with a variety of neutrophil-derived proteins including the enzyme myeloperoxidase (MPO). Studies into the mechanisms leading to the formation of NETs indicate a complex process that differs according to the stimulus. With some stimuli an active nicotinamide adenine dinucleotide phosphate (NADPH) oxidase is required. However, assigning specific reactive oxygen species involved downstream of the oxidase is a difficult task and definitive proof for any single oxidant is still lacking. Pharmacological inhibition of MPO and the use of MPO-deficient neutrophils indicate active MPO is required with phorbol myristate acetate as a stimulus but not necessarily with bacteria. Reactive oxidants and MPO may also play a role in NET-mediated microbial killing. MPO is present on NETs and maintains activity at this site. Therefore, MPO has the potential to generate reactive oxidants in close proximity to trapped microorganisms and thus effect microbial killing. This brief review discusses current evidence for the involvement of reactive oxidants and MPO in NET formation and their potential contribution to NET antimicrobial activity. PMID:23346086

  5. Fosfomycin enhances phagocyte-mediated killing of Staphylococcus aureus by extracellular traps and reactive oxygen species

    PubMed Central

    Shen, Fengge; Tang, Xudong; Cheng, Wei; Wang, Yang; Wang, Chao; Shi, Xiaochen; An, Yanan; Zhang, Qiaoli; Liu, Mingyuan; Liu, Bo; Yu, Lu

    2016-01-01

    The successful treatment of bacterial infections is the achievement of a synergy between the host’s immune defences and antibiotics. Here, we examined whether fosfomycin (FOM) could improve the bactericidal effect of phagocytes, and investigated the potential mechanisms. FOM enhanced the phagocytosis and extra- or intracellular killing of S. aureus by phagocytes. And FOM enhanced the extracellular killing of S. aureus in macrophage (MФ) and in neutrophils mediated by extracellular traps (ETs). ET production was related to NADPH oxidase-dependent reactive oxygen species (ROS). Additionally, FOM increased the intracellular killing of S. aureus in phagocytes, which was mediated by ROS through the oxidative burst process. Our results also showed that FOM alone induced S. aureus producing hydroxyl radicals in order to kill the bacterial cells in vitro. In a mouse peritonitis model, FOM treatment increased the bactericidal extra- and intracellular activity in vivo, and FOM strengthened ROS and ET production from peritoneal lavage fluid ex vivo. An IVIS imaging system assay further verified the observed in vivo bactericidal effect of the FOM treatment. This work may provide a deeper understanding of the role of the host’s immune defences and antibiotic interactions in microbial infections. PMID:26778774

  6. Fosfomycin enhances phagocyte-mediated killing of Staphylococcus aureus by extracellular traps and reactive oxygen species.

    PubMed

    Shen, Fengge; Tang, Xudong; Cheng, Wei; Wang, Yang; Wang, Chao; Shi, Xiaochen; An, Yanan; Zhang, Qiaoli; Liu, Mingyuan; Liu, Bo; Yu, Lu

    2016-01-01

    The successful treatment of bacterial infections is the achievement of a synergy between the host's immune defences and antibiotics. Here, we examined whether fosfomycin (FOM) could improve the bactericidal effect of phagocytes, and investigated the potential mechanisms. FOM enhanced the phagocytosis and extra- or intracellular killing of S. aureus by phagocytes. And FOM enhanced the extracellular killing of S. aureus in macrophage (MФ) and in neutrophils mediated by extracellular traps (ETs). ET production was related to NADPH oxidase-dependent reactive oxygen species (ROS). Additionally, FOM increased the intracellular killing of S. aureus in phagocytes, which was mediated by ROS through the oxidative burst process. Our results also showed that FOM alone induced S. aureus producing hydroxyl radicals in order to kill the bacterial cells in vitro. In a mouse peritonitis model, FOM treatment increased the bactericidal extra- and intracellular activity in vivo, and FOM strengthened ROS and ET production from peritoneal lavage fluid ex vivo. An IVIS imaging system assay further verified the observed in vivo bactericidal effect of the FOM treatment. This work may provide a deeper understanding of the role of the host's immune defences and antibiotic interactions in microbial infections. PMID:26778774

  7. Extracellular ultrathin fibers sensitive to intracellular reactive oxygen species: Formation of intercellular membrane bridges

    SciTech Connect

    Jung, Se-Hui; Park, Jin-Young; Joo, Jung-Hoon; Kim, Young-Myeong; Ha, Kwon-Soo

    2011-07-15

    Membrane bridges are key cellular structures involved in intercellular communication; however, dynamics for their formation are not well understood. We demonstrated the formation and regulation of novel extracellular ultrathin fibers in NIH3T3 cells using confocal and atomic force microscopy. At adjacent regions of neighboring cells, phorbol 12-myristate 13-acetate (PMA) and glucose oxidase induced ultrathin fiber formation, which was prevented by Trolox, a reactive oxygen species (ROS) scavenger. The height of ROS-sensitive ultrathin fibers ranged from 2 to 4 nm. PMA-induced formation of ultrathin fibers was inhibited by cytochalasin D, but not by Taxol or colchicine, indicating that ultrathin fibers mainly comprise microfilaments. PMA-induced ultrathin fibers underwent dynamic structural changes, resulting in formation of intercellular membrane bridges. Thus, these fibers are formed by a mechanism(s) involving ROS and involved in formation of intercellular membrane bridges. Furthermore, ultrastructural imaging of ultrathin fibers may contribute to understanding the diverse mechanisms of cell-to-cell communication and the intercellular transfer of biomolecules, including proteins and cell organelles.

  8. Species-level variability in extracellular production rates of reactive oxygen species by diatoms

    NASA Astrophysics Data System (ADS)

    Schneider, Robin; Roe, Kelly; Hansel, Colleen; Voelker, Bettina

    2016-03-01

    Biological production and decay of the reactive oxygen species (ROS) hydrogen peroxide (H2O2) and superoxide (O2-) likely have significant effects on the cycling of trace metals and carbon in marine systems. In this study, extracellular production rates of H2O2 and O2- were determined for five species of marine diatoms in the presence and absence of light. Production of both ROS was measured in parallel by suspending cells on filters and measuring the ROS downstream using chemiluminescence probes. In addition, the ability of these organisms to break down O2- and H2O2 was examined by measuring recovery of O2- and H2O2 added to the influent medium. O2- production rates ranged from undetectable to 7.3 x 10-16 mol cell-1 hr-1, while H2O2 production rates ranged from undetectable to 3.4 x 10-16 mol cell-1 hr-1. Results suggest that extracellular ROS production occurs through a variety of pathways even amongst organisms of the same genus. Thalassiosira spp. produced more O2- in light than dark, even when the organisms were killed, indicating that O2- is produced via a passive photochemical process on the cell surface. The ratio of H2O¬2 to O2- production rates was consistent with production of H2O2 solely through dismutation of O2- for T. oceanica, while T. pseudonana made much more H2O2 than O2 . T. weissflogii only produced H2O2 when stressed or killed. P. tricornutum cells did not make cell-associated ROS, but did secrete H2O2-producing substances into the growth medium. In all organisms, recovery rates for killed cultures (94-100% H2O2; 10-80% O2-) were consistently higher than those for live cultures (65-95% H2O2; 10-50% O2-). While recovery rates for killed cultures in H2O2 indicate that nearly all H2O2 was degraded by active cell processes, O2- decay appeared to occur via a combination of active and passive processes. Overall, this study shows that the rates and pathways for ROS production and decay vary greatly among diatom species, even between those that are

  9. Species-Level Variability in Extracellular Production Rates of Reactive Oxygen Species by Diatoms.

    PubMed

    Schneider, Robin J; Roe, Kelly L; Hansel, Colleen M; Voelker, Bettina M

    2016-01-01

    Biological production and decay of the reactive oxygen species (ROS) hydrogen peroxide (H2O2) and superoxide (O[Formula: see text]) likely have significant effects on the cycling of trace metals and carbon in marine systems. In this study, extracellular production rates of H2O2 and O[Formula: see text] were determined for five species of marine diatoms in the presence and absence of light. Production of both ROS was measured in parallel by suspending cells on filters and measuring the ROS downstream using chemiluminescence probes. In addition, the ability of these organisms to break down O[Formula: see text] and H2O2 was examined by measuring recovery of O[Formula: see text] and H2O2 added to the influent medium. O[Formula: see text] production rates ranged from undetectable to 7.3 × 10(-16) mol cell(-1) h(-1), while H2O2 production rates ranged from undetectable to 3.4 × 10(-16) mol cell(-1) h(-1). Results suggest that extracellular ROS production occurs through a variety of pathways even amongst organisms of the same genus. Thalassiosira spp. produced more O[Formula: see text] in light than dark, even when the organisms were killed, indicating that O[Formula: see text] is produced via a passive photochemical process on the cell surface. The ratio of H2O2 to O[Formula: see text] production rates was consistent with production of H2O2 solely through dismutation of O[Formula: see text] for T. oceanica, while T. pseudonana made much more H2O2 than O[Formula: see text]. T. weissflogii only produced H2O2 when stressed or killed. P. tricornutum cells did not make cell-associated ROS, but did secrete H2O2-producing substances into the growth medium. In all organisms, recovery rates for killed cultures (94-100% H2O2; 10-80% O[Formula: see text]) were consistently higher than those for live cultures (65-95% H2O2; 10-50% O[Formula: see text]). While recovery rates for killed cultures in H2O2 indicate that nearly all H2O2 was degraded by active cell processes, O

  10. Species-Level Variability in Extracellular Production Rates of Reactive Oxygen Species by Diatoms

    PubMed Central

    Schneider, Robin J.; Roe, Kelly L.; Hansel, Colleen M.; Voelker, Bettina M.

    2016-01-01

    Biological production and decay of the reactive oxygen species (ROS) hydrogen peroxide (H2O2) and superoxide (O2-) likely have significant effects on the cycling of trace metals and carbon in marine systems. In this study, extracellular production rates of H2O2 and O2- were determined for five species of marine diatoms in the presence and absence of light. Production of both ROS was measured in parallel by suspending cells on filters and measuring the ROS downstream using chemiluminescence probes. In addition, the ability of these organisms to break down O2- and H2O2 was examined by measuring recovery of O2- and H2O2 added to the influent medium. O2- production rates ranged from undetectable to 7.3 × 10−16 mol cell−1 h−1, while H2O2 production rates ranged from undetectable to 3.4 × 10−16 mol cell−1 h−1. Results suggest that extracellular ROS production occurs through a variety of pathways even amongst organisms of the same genus. Thalassiosira spp. produced more O2- in light than dark, even when the organisms were killed, indicating that O2- is produced via a passive photochemical process on the cell surface. The ratio of H2O2 to O2- production rates was consistent with production of H2O2 solely through dismutation of O2- for T. oceanica, while T. pseudonana made much more H2O2 than O2-. T. weissflogii only produced H2O2 when stressed or killed. P. tricornutum cells did not make cell-associated ROS, but did secrete H2O2-producing substances into the growth medium. In all organisms, recovery rates for killed cultures (94–100% H2O2; 10–80% O2-) were consistently higher than those for live cultures (65–95% H2O2; 10–50% O2-). While recovery rates for killed cultures in H2O2 indicate that nearly all H2O2 was degraded by active cell processes, O2- decay appeared to occur via a combination of active and passive processes. Overall, this study shows that the rates and pathways for ROS production and decay vary greatly among diatom species, even

  11. Calcite formation in soft coral sclerites is determined by a single reactive extracellular protein.

    PubMed

    Rahman, M Azizur; Oomori, Tamotsu; Wörheide, Gert

    2011-09-01

    Calcium carbonate exists in two main forms, calcite and aragonite, in the skeletons of marine organisms. The primary mineralogy of marine carbonates has changed over the history of the earth depending on the magnesium/calcium ratio in seawater during the periods of the so-called "calcite and aragonite seas." Organisms that prefer certain mineralogy appear to flourish when their preferred mineralogy is favored by seawater chemistry. However, this rule is not without exceptions. For example, some octocorals produce calcite despite living in an aragonite sea. Here, we address the unresolved question of how organisms such as soft corals are able to form calcitic skeletal elements in an aragonite sea. We show that an extracellular protein called ECMP-67 isolated from soft coral sclerites induces calcite formation in vitro even when the composition of the calcifying solution favors aragonite precipitation. Structural details of both the surface and the interior of single crystals generated upon interaction with ECMP-67 were analyzed with an apertureless-type near-field IR microscope with high spatial resolution. The results show that this protein is the main determining factor for driving the production of calcite instead of aragonite in the biocalcification process and that -OH, secondary structures (e.g. α-helices and amides), and other necessary chemical groups are distributed over the center of the calcite crystals. Using an atomic force microscope, we also explored how this extracellular protein significantly affects the molecular-scale kinetics of crystal formation. We anticipate that a more thorough investigation of the proteinaceous skeleton content of different calcite-producing marine organisms will reveal similar components that determine the mineralogy of the organisms. These findings have significant implications for future models of the crystal structure of calcite in nature. PMID:21768106

  12. Calcite Formation in Soft Coral Sclerites Is Determined by a Single Reactive Extracellular Protein*

    PubMed Central

    Rahman, M. Azizur; Oomori, Tamotsu; Wörheide, Gert

    2011-01-01

    Calcium carbonate exists in two main forms, calcite and aragonite, in the skeletons of marine organisms. The primary mineralogy of marine carbonates has changed over the history of the earth depending on the magnesium/calcium ratio in seawater during the periods of the so-called “calcite and aragonite seas.” Organisms that prefer certain mineralogy appear to flourish when their preferred mineralogy is favored by seawater chemistry. However, this rule is not without exceptions. For example, some octocorals produce calcite despite living in an aragonite sea. Here, we address the unresolved question of how organisms such as soft corals are able to form calcitic skeletal elements in an aragonite sea. We show that an extracellular protein called ECMP-67 isolated from soft coral sclerites induces calcite formation in vitro even when the composition of the calcifying solution favors aragonite precipitation. Structural details of both the surface and the interior of single crystals generated upon interaction with ECMP-67 were analyzed with an apertureless-type near-field IR microscope with high spatial resolution. The results show that this protein is the main determining factor for driving the production of calcite instead of aragonite in the biocalcification process and that –OH, secondary structures (e.g. α-helices and amides), and other necessary chemical groups are distributed over the center of the calcite crystals. Using an atomic force microscope, we also explored how this extracellular protein significantly affects the molecular-scale kinetics of crystal formation. We anticipate that a more thorough investigation of the proteinaceous skeleton content of different calcite-producing marine organisms will reveal similar components that determine the mineralogy of the organisms. These findings have significant implications for future models of the crystal structure of calcite in nature. PMID:21768106

  13. Guanidino compounds generate reactive oxygen species.

    PubMed

    Mori, A; Kohno, M; Masumizu, T; Noda, Y; Packer, L

    1996-09-01

    Methylguanidine, guanidinoacetic acid and guanidinosuccinic acid are endogenous substances in body tissues. Extremely high levels of these substances are known to be related to the pathogenesis of epilepsy and renal failure such as uremia. In this study it was demonstrated that methylguanidine, guanidinoacetic acid and guanidinosuccinic acid, and arginine generate hydroxyl radicals in aqueous solution. These findings suggest that a high level of guanidino compounds accumulating near or within cells such as neurons (in an epileptogenic focus) or nephrons (in uremic patients) may cause free radical damage leading to these clinical disorders. Arginine may have a similar role in the pathogenesis of hyperarginemia. PMID:8886279

  14. Local control of reactive power by distributed photovoltaic generators

    SciTech Connect

    Chertkov, Michael; Turitsyn, Konstantin; Sulc, Petr; Backhaus, Scott

    2010-01-01

    High penetration levels of distributed photovoltaic (PV) generation on an electrical distribution circuit may severely degrade power quality due to voltage sags and swells caused by rapidly varying PV generation during cloud transients coupled with the slow response of existing utility compensation and regulation equipment. Although not permitted under current standards for interconnection of distributed generation, fast-reacting, VAR-capable PV inverters may provide the necessary reactive power injection or consumption to maintain voltage regulation under difficult transient conditions. As side benefit, the control of reactive power injection at each PV inverter provides an opportunity and a new tool for distribution utilities to optimize the performance of distribution circuits, e.g. by minimizing thermal losses. We suggest a local control scheme that dispatches reactive power from each PV inverter based on local instantaneous measurements of the real and reactive components of the consumed power and the real power generated by the PVs. Using one adjustable parameter per circuit, we balance the requirements on power quality and desire to minimize thermal losses. Numerical analysis of two exemplary systems, with comparable total PV generation albeit a different spatial distribution, show how to adjust the optimization parameter depending on the goal. Overall, this local scheme shows excellent performance; it's capable of guaranteeing acceptable power quality and achieving significant saving in thermal losses in various situations even when the renewable generation in excess of the circuit own load, i.e. feeding power back to the higher-level system.

  15. Competitive adsorption of Reactive Orange 16 and Reactive Brilliant Blue R on polyaniline/bacterial extracellular polysaccharides composite--a novel eco-friendly polymer.

    PubMed

    Janaki, V; Vijayaraghavan, K; Ramasamy, A K; Lee, Kui-Jae; Oh, Byung-Taek; Kamala-Kannan, Seralathan

    2012-11-30

    The performance of polyaniline/extracellular polymeric substances (Pn/EPS) composite as an adsorbent to remove the anionic reactive dyes, Reactive Brilliant Blue R (RBBR) and Reactive Orange 16 (RO), was investigated in single and binary systems. The pH(pzc) of Pn/EPS composite was calculated as 3.7 through potentiometric mass titration method. Electrostatic interaction between the dye anion and the nitrogen present in the polymer was identified as a major mechanism in adsorption process. Single component isotherms followed the Langmuir model with the maximum adsorption capacity of 0.5775 mmol g(-1) for RBBR and 0.4748 mmol g(-1) for RO. In binary system, both the reactive dye anions compete with each other and resulted in lower uptake. Binary adsorption data were interpreted well by the Sheindorf-Rehbun-Sheintuch equation as compared to extended Langmuir model with constant interaction factor. Kinetic analysis of single solute followed pseudo-first order model. Thermodynamic studies computed that RBBR and RO adsorption was endothermic, spontaneous, and feasible process. PMID:23036702

  16. Reactive oxygen species generation and signaling in plants

    PubMed Central

    Tripathy, Baishnab Charan; Oelmüller, Ralf

    2012-01-01

    The introduction of molecular oxygen into the atmosphere was accompanied by the generation of reactive oxygen species (ROS) as side products of many biochemical reactions. ROS are permanently generated in plastids, peroxisomes, mitochiondria, the cytosol and the apoplast. Imbalance between ROS generation and safe detoxification generates oxidative stress and the accumulating ROS are harmful for the plants. On the other hand, specific ROS function as signaling molecules and activate signal transduction processes in response to various stresses. Here, we summarize the generation of ROS in the different cellular compartments and the signaling processes which are induced by ROS. PMID:23072988

  17. The Role of Reactive Oxygen Species (ROS) in the Formation of Extracellular Traps (ETs) in Humans

    PubMed Central

    Stoiber, Walter; Obermayer, Astrid; Steinbacher, Peter; Krautgartner, Wolf-Dietrich

    2015-01-01

    Extracellular traps (ETs) are reticulate structures of extracellular DNA associated with antimicrobial molecules. Their formation by phagocytes (mainly by neutrophils: NETs) has been identified as an essential element of vertebrate innate immune defense. However, as ETs are also toxic to host cells and potent triggers of autoimmunity, their role between pathogen defense and human pathogenesis is ambiguous, and they contribute to a variety of acute and chronic inflammatory diseases. Since the discovery of ET formation (ETosis) a decade ago, evidence has accumulated that most reaction cascades leading to ET release involve ROS. An important new facet was added when it became apparent that ETosis might be directly linked to, or be a variant of, the autophagy cell death pathway. The present review analyzes the evidence to date on the interplay between ROS, autophagy and ETosis, and highlights and discusses several further aspects of the ROS-ET relationship that are incompletely understood. These aspects include the role of NADPH oxidase-derived ROS, the molecular requirements of NADPH oxidase-dependent ETosis, the roles of NADPH oxidase subtypes, extracellular ROS and of ROS from sources other than NADPH oxidase, and the present evidence for ROS-independent ETosis. We conclude that ROS interact with ETosis in a multidimensional manner, with influence on whether ETosis shows beneficial or detrimental effects. PMID:25946076

  18. Carrageenan-induced inflammation promotes ROS generation and neutrophil extracellular trap formation in a mouse model of peritonitis.

    PubMed

    Barth, Cristiane R; Funchal, Giselle A; Luft, Carolina; de Oliveira, Jarbas R; Porto, Bárbara N; Donadio, Márcio V F

    2016-04-01

    Neutrophil extracellular traps (NETs) are a combination of DNA fibers and granular proteins, such as neutrophil elastase (NE). NETs are released in the extracellular space in response to different stimuli. Carrageenan is a sulfated polysaccharide extracted from Chondrus crispus, a marine algae, used for decades in research for its potential to induce inflammation in different animal models. In this study, we show for the first time that carrageenan injection can induce NET release in a mouse model of acute peritonitis. Carrageenan induced NET release by viable neutrophils with NE and myeloperoxidase (MPO) expressed on DNA fibers. Furthermore, although this polysaccharide was able to stimulate reactive oxygen species (ROS) generation by peritoneal neutrophils, NADPH oxidase derived ROS were dispensable for NET formation by carrageenan. In conclusion, our results show that carrageenan-induced inflammation in the peritoneum of mice can induce NET formation in an ROS-independent manner. These results may add important information to the field of inflammation and potentially lead to novel anti-inflammatory agents targeting the production of NETs. PMID:26786873

  19. Reactive Oxygen Species (ROS) generation by lunar simulants

    NASA Astrophysics Data System (ADS)

    Kaur, Jasmeet; Rickman, Douglas; Schoonen, Martin A.

    2016-05-01

    The current interest in human exploration of the Moon and past experiences of Apollo astronauts has rekindled interest into the possible harmful effects of lunar dust on human health. In comparison to the Apollo-era explorations, human explorers may be weeks on the Moon, which will raise the risk of inhalation exposure. The mineralogical composition of lunar dust is well documented, but its effects on human health are not fully understood. With the aim of understanding the reactivity of dusts that may be encountered on geologically different lunar terrains, we have studied Reactive Oxygen Species (ROS) generation by a suite of lunar simulants of different mineralogical-chemical composition dispersed in water and Simulated Lung Fluid (SLF). To further explore the reactivity of simulants under lunar environmental conditions, we compared the reactivity of simulants both in air and inert atmosphere. As the impact of micrometeorites with consequent shock-induced stresses is a major environmental factor on the Moon, we also studied the effect of mechanical stress on samples. Mechanical stress was induced by hand crushing the samples both in air and inert atmosphere. The reactivity of samples after crushing was analyzed for a period of up to nine days. Hydrogen peroxide (H2O2) in water and SLF was analyzed by an in situ electrochemical probe and hydroxyl radical (•OH) by Electron Spin Resonance (ESR) spectroscopy and Adenine probe. Out of all simulants, CSM-CL-S was found to be the most reactive simulant followed by OB-1 and then JSC-1A simulant. The overall reactivity of samples in the inert atmosphere was higher than in air. Fresh crushed samples showed a higher level of reactivity than uncrushed samples. Simulant samples treated to create agglutination, including the formation of zero-valent iron, showed less reactivity than untreated simulants. ROS generation in SLF is initially slower than in deionized water (DI), but the ROS formation is sustained for as long as 7

  20. Disulfiram anti-cancer efficacy without copper overload is enhanced by extracellular H2O2 generation: antagonism by tetrathiomolybdate

    PubMed Central

    Calderon-Aparicio, Ali; Strasberg-Rieber, Mary; Rieber, Manuel

    2015-01-01

    Highlights exogenous SOD increases apoptosis by sub-toxic disulfiram without copper overload H2O2 generation from glucose oxidase also potentiates disulfiram toxicity N-acetylcysteine suppresses antitumor potentiation of DSF by H2O2 generation sub-toxic tetrathiomolybdate inhibits potentiation of DSF by SOD Background Cu/Zn superoxide dismutases (SODs) like the extracellular SOD3 and cytoplasmic SOD1 regulate cell proliferation by generating hydrogen peroxide (H2O2). This pro-oxidant inactivates essential cysteine residues in protein tyrosine phosphatases (PTP) helping receptor tyrosine kinase activation by growth factor signaling, and further promoting downstream MEK/ERK linked cell proliferation. Disulfiram (DSF), currently in clinical cancer trials is activated by copper chelation, being potentially capable of diminishing the copper dependent activation of MEK1/2 and SOD1/SOD3 and promoting reactive oxygen species (ROS) toxicity. However, copper (Cu) overload may occur when co-administered with DSF, resulting in toxicity and mutagenicity against normal tissue, through generation of the hydroxyl radical (•OH) by the Fenton reaction. Purpose To investigate: a) whether sub-toxic DSF efficacy can be increased without Cu overload against human melanoma cells with unequal BRAF(V600E) mutant status and Her2-overexpressing SKBR3 breast cancer cells, by increasing H2O2from exogenous SOD; b) to compare the anti-tumor efficacy of DSF with that of another clinically used copper chelator, tetrathiomolybdate (TTM) Results a) without copper supplementation, exogenous SOD potentiated sub-toxic DSF toxicity antagonized by sub-toxic TTM or by the anti-oxidant N-acetylcysteine; b) exogenous glucose oxidase, another H2O2 generator resembled exogenous SOD in potentiating sub-toxic DSF. Conclusions potentiation of sub-lethal DSF toxicity by extracellular H2O2 against the human tumor cell lines investigated, only requires basal Cu and increased ROS production, being unrelated to non

  1. Reactive microgliosis: extracellular μ-calpain and microglia-mediated dopaminergic neurotoxicity

    PubMed Central

    Levesque, Shannon; Wilson, Belinda; Gregoria, Vincent; Thorpe, Laura B.; Dallas, Shannon; Polikov, Vadim S.; Hong, Jau-Shyong

    2010-01-01

    Microglia, the innate immune cells in the brain, can become chronically activated in response to dopaminergic neuron death, fuelling a self-renewing cycle of microglial activation followed by further neuron damage (reactive microgliosis), which is implicated in the progressive nature of Parkinson’s disease. Here, we use an in vitro approach to separate neuron injury factors from the cellular actors of reactive microgliosis and discover molecular signals responsible for chronic and toxic microglial activation. Upon injury with the dopaminergic neurotoxin 1-methyl-4-phenylpyridinium, N27 cells (dopaminergic neuron cell line) released soluble neuron injury factors that activated microglia and were selectively toxic to dopaminergic neurons in mixed mesencephalic neuron-glia cultures through nicotinamide adenine dinucleotide phosphate oxidase. μ-Calpain was identified as a key signal released from damaged neurons, causing selective dopaminergic neuron death through activation of microglial nicotinamide adenine dinucleotide phosphate oxidase and superoxide production. These findings suggest that dopaminergic neurons may be inherently susceptible to the pro-inflammatory effects of neuron damage, i.e. reactive microgliosis, providing much needed insight into the chronic nature of Parkinson’s disease. PMID:20123724

  2. Phenazine production enhances extracellular DNA release via hydrogen peroxide generation in Pseudomonas aeruginosa

    PubMed Central

    Das, Theerthankar; Manefield, Mike

    2013-01-01

    In Pseudomonas aeruginosa eDNA is a crucial component essential for biofilm formation and stability. In this study we report that release of eDNA is influenced by the production of phenazine in P. aeruginosa. A ∆phzA-G mutant of P. aeruginosa PA14 deficient in phenazine production generated significantly less eDNA in comparison with the phenazine producing strains. The relationship between eDNA release and phenazine production is bridged via hydrogen peroxide (H2O2) generation and subsequent H2O2 mediated cell lysis and ultimately release of chromosomal DNA into the extracellular environment as eDNA. PMID:23710274

  3. Designer Extracellular Matrix Based on DNA-Peptide Networks Generated by Polymerase Chain Reaction.

    PubMed

    Finke, Alexander; Bußkamp, Holger; Manea, Marilena; Marx, Andreas

    2016-08-16

    Cell proliferation and differentiation in multicellular organisms are partially regulated by signaling from the extracellular matrix. The ability to mimic an extracellular matrix would allow particular cell types to be specifically recognized, which is central to tissue engineering. We present a new functional DNA-based material with cell-adhesion properties. It is generated by using covalently branched DNA as primers in PCR. These primers were functionalized by click chemistry with the cyclic peptide c(RGDfK), a peptide that is known to predominantly bind to αvβ3 integrins, which are found on endothelial cells and fibroblasts, for example. As a covalent coating of surfaces, this DNA-based material shows cell-repellent properties in its unfunctionalized state and gains adhesiveness towards specific target cells when functionalized with c(RGDfK). These cells remain viable and can be released under mild conditions by DNase I treatment. PMID:27410200

  4. Cis-urocanic acid inhibits bovine neutrophil generation of extracellular superoxide

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Neutrophils play a fundamental role in the host innate immune response during mastitis and other bacterial-mediated diseases of cattle through their ability to phagocytose and kill bacteria. The ability of neutrophils to kill bacteria is mediated through the generation of reactive oxygen species (R...

  5. Decolorization and biodegradation of reactive blue 220 textile dye by Lentinus crinitus extracellular extract.

    PubMed

    Niebisch, Carolina Heyse; Malinowski, Alexandre Knoll; Schadeck, Ruth; Mitchell, David A; Kava-Cordeiro, Vanessa; Paba, Jaime

    2010-08-15

    Studies were carried on the decolorization of the textile dye reactive blue 220 (RB220) by a novel isolate of Lentinus crinitus fungi. The optimal conditions for the production of destaining activity were obtained in media containing intermediate concentrations of ammonium oxalate and glucose (10 g L(-1)) as nitrogen and carbon sources, respectively, at 28 degrees C and pH 5.5. Maximum decolorization efficiency against RB220 achieved in this study was around 95%. Ultra-violet and visible (UV-vis) spectrophotometric analyses, before and after decolorization, suggest that decolorization was due to biodegradation. This effect was associated with a putative low molecular weight laccase (41 kDa) displaying good tolerance to a wide range of pH values, salt concentrations and temperatures, suggesting a potential role for this organism in the remediation of real dye containing effluents. PMID:20452721

  6. Extracellular ATP promotes stomatal opening of Arabidopsis thaliana through heterotrimeric G protein α subunit and reactive oxygen species.

    PubMed

    Hao, Li-Hua; Wang, Wei-Xia; Chen, Chen; Wang, Yu-Fang; Liu, Ting; Li, Xia; Shang, Zhong-Lin

    2012-07-01

    In recent years, adenosine tri-phosphate (ATP) has been reported to exist in apoplasts of plant cells as a signal molecule. Extracellular ATP (eATP) plays important roles in plant growth, development, and stress tolerance. Here, extracellular ATP was found to promote stomatal opening of Arabidopsis thaliana in light and darkness. ADP, GTP, and weakly hydrolyzable ATP analogs (ATPγS, Bz-ATP, and 2meATP) showed similar effects, whereas AMP and adenosine did not affect stomatal movement. Apyrase inhibited stomatal opening. ATP-promoted stomatal opening was blocked by an NADPH oxidase inhibitor (diphenylene iodonium) or deoxidizer (dithiothreitol), and was impaired in null mutant of NADPH oxidase (atrbohD/F). Added ATP triggered ROS generation in guard cells via NADPH oxidase. ATP also induced Ca(2+) influx and H(+) efflux in guard cells. In atrbohD/F, ATP-induced ion flux was strongly suppressed. In null mutants of the heterotrimeric G protein α subunit, ATP-promoted stomatal opening, cytoplasmic ROS generation, Ca(2+) influx, and H(+) efflux were all suppressed. These results indicated that eATP-promoted stomatal opening possibly involves the heterotrimeric G protein, ROS, cytosolic Ca(2+), and plasma membrane H(+)-ATPase. PMID:22138967

  7. Detecting, Visualizing and Quantitating the Generation of Reactive Oxygen Species in an Amoeba Model System

    PubMed Central

    Zhang, Xuezhi; Soldati, Thierry

    2013-01-01

    Reactive oxygen species (ROS) comprise a range of reactive and short-lived, oxygen-containing molecules, which are dynamically interconverted or eliminated either catalytically or spontaneously. Due to the short life spans of most ROS and the diversity of their sources and subcellular localizations, a complete picture can be obtained only by careful measurements using a combination of protocols. Here, we present a set of three different protocols using OxyBurst Green (OBG)-coated beads, or dihydroethidium (DHE) and Amplex UltraRed (AUR), to monitor qualitatively and quantitatively various ROS in professional phagocytes such as Dictyostelium. We optimised the beads coating procedures and used OBG-coated beads and live microscopy to dynamically visualize intraphagosomal ROS generation at the single cell level. We identified lipopolysaccharide (LPS) from E. coli as a potent stimulator for ROS generation in Dictyostelium. In addition, we developed real time, medium-throughput assays using DHE and AUR to quantitatively measure intracellular superoxide and extracellular H2O2 production, respectively. PMID:24300479

  8. A thermoresponsive bubble-generating liposomal system for triggering localized extracellular drug delivery.

    PubMed

    Chen, Ko-Jie; Liang, Hsiang-Fa; Chen, Hsin-Lung; Wang, Yucai; Cheng, Po-Yuan; Liu, Hao-Li; Xia, Younan; Sung, Hsing-Wen

    2013-01-22

    The therapeutic effectiveness of chemotherapy is optimal only when tumor cells are subjected to a maximum drug exposure. To increase the intratumoral drug concentration and thus the efficacy of chemotherapy, a thermoresponsive bubble-generating liposomal system is proposed for triggering localized extracellular drug delivery. The key component of this liposomal formulation is the encapsulated ammonium bicarbonate (ABC), which is used to create the transmembrane gradient needed for a highly efficient encapsulation of doxorubicin (DOX). At an elevated temperature (42 °C), decomposition of ABC generates CO(2) bubbles, creating permeable defects in the lipid bilayer that rapidly release DOX and instantly increase the drug concentration locally. Because the generated CO(2) bubbles are hyperechogenic, they also enhance ultrasound imaging. Consequently, this new liposomal system encapsulated with ABC may also provide an ability to monitor a temperature-controlled drug delivery process. PMID:23240550

  9. Generation of specific monoclonal antibodies against the extracellular loops of human claudin-3 by immunizing mice with target-expressing cells.

    PubMed

    Ando, Hiroshi; Suzuki, Masayo; Kato-Nakano, Mariko; Kawamoto, Shinobu; Misaka, Hirofumi; Kimoto, Naoya; Furuya, Akiko; Nakamura, Kazuyasu

    2015-01-01

    Human claudin-3 (CLDN3) is a tetraspanin transmembrane protein of tight junction structures and is known to be over-expressed in some malignant tumors. Although a specific monoclonal antibody (MAb) against the extracellular domains of CLDN3 would be a valuable tool, generation of such MAbs has been regarded as difficult using traditional hybridoma techniques, because of the conserved sequence homology of CLDN3s among various species. In addition, high sequence similarity is shared among claudin family members, and potential cross-reactivity of MAb should be evaluated carefully. To overcome these difficulties, we generated CLDN3-expressing Chinese hamster ovary and Sf9 cells to use an immunogens and performed cell-based screening to eliminate cross-reactive antibodies. As a result, we generated MAbs that recognized the extracellular loops of CLDN3 but not those of CLDN4, 5, 6, or 9. Further in vitro studies suggested that the isolated MAbs possessed the desired binding properties for the detection or targeting of CLDN3. PMID:25744656

  10. Complement factor H modulates the activation of human neutrophil granulocytes and the generation of neutrophil extracellular traps.

    PubMed

    Schneider, Andrea E; Sándor, Noémi; Kárpáti, Éva; Józsi, Mihály

    2016-04-01

    Factor H (FH) is a major inhibitor of the alternative pathway of complement activation in plasma and on certain host surfaces. In addition to being a complement regulator, FH can bind to various cells via specific receptors, including binding to neutrophil granulocytes through complement receptor type 3 (CR3; CD11b/CD18), and modulate their function. The cellular roles of FH are, however, poorly understood. Because neutrophils are important innate immune cells in inflammatory processes and the host defense against pathogens, we aimed at studying the effects of FH on various neutrophil functions, including the generation of extracellular traps. FH co-localized with CD11b on the surface of neutrophils isolated from peripheral blood of healthy individuals, and cell-bound FH retained its cofactor activity and enhanced C3b degradation. Soluble FH supported neutrophil migration and immobilized FH induced cell spreading. In addition, immobilized but not soluble FH enhanced IL-8 release from neutrophils. FH alone did not trigger the cells to produce neutrophil extracellular traps (NETs), but NET formation induced by PMA and by fibronectin plus fungal β-glucan were inhibited by immobilized, but not by soluble, FH. Moreover, in parallel with NET formation, immobilized FH also inhibited the production of reactive oxygen species induced by PMA and by fibronectin plus β-glucan. Altogether, these data indicate that FH has multiple regulatory roles on neutrophil functions. While it can support the recruitment of neutrophils, FH may also exert anti-inflammatory effects and influence local inflammatory and antimicrobial reactions, and reduce tissue damage by modulating NET formation. PMID:26938503

  11. Method for generating a highly reactive plasma for exhaust gas aftertreatment and enhanced catalyst reactivity

    DOEpatents

    Whealton, John H.; Hanson, Gregory R.; Storey, John M.; Raridon, Richard J.; Armfield, Jeffrey S.; Bigelow, Timothy S.; Graves, Ronald L.

    2002-01-01

    A method for non-thermal plasma aftertreatment of exhaust gases the method comprising the steps of providing short risetime, high frequency, high power bursts of low-duty factor microwaves sufficient to generate a plasma discharge and passing a gas to be treated through the discharge so as to cause dissociative reduction of the exhaust gases and enhanced catalyst reactivity through application of the pulsed microwave fields directly to the catalyst material sufficient to cause a polarizability catastrophe and enhanced heating of the metal crystallite particles of the catalyst, and in the presence or absence of the plasma. The invention also includes a reactor for aftertreatment of exhaust gases.

  12. Autophagy and Reactive Oxygen Species Are Involved in Neutrophil Extracellular Traps Release Induced by C. albicans Morphotypes

    PubMed Central

    Kenno, Samyr; Perito, Stefano; Mosci, Paolo; Vecchiarelli, Anna; Monari, Claudia

    2016-01-01

    Neutrophil extracellular traps (NETs) are a combination of DNA fibers and granular enzymes, such as elastase and myeloperoxidase. In this study, we demonstrate that Candida albicans hyphal (CAH) cells and yeast (CAY) cells induce differential amounts, kinetics and mechanisms of NET release. CAH cells induced larger quantities of NET compared to CAY cells and can stimulate rapid NET formation up to 4 h of incubation. CAY cells are, also, able to induce rapid NET formation, but this ability was lost at 4 h. Both reactive oxygen species (ROS) and autophagy are implicated in NET induced by CAH and CAY cells, but with a time-different participation of these two mechanisms. In particular, in the early phase (15 min) CAH cells stimulate NET via autophagy, but not via ROS, while CAY cells induce NET via both autophagy and ROS. At 4 h, only CAH cells stimulate NET formation using autophagy as well as ROS. Finally, we demonstrate that NET release, in response to CAH cells, involves NF-κB activation and is strongly implicated in hyphal destruction. PMID:27375599

  13. Autophagy and Reactive Oxygen Species Are Involved in Neutrophil Extracellular Traps Release Induced by C. albicans Morphotypes.

    PubMed

    Kenno, Samyr; Perito, Stefano; Mosci, Paolo; Vecchiarelli, Anna; Monari, Claudia

    2016-01-01

    Neutrophil extracellular traps (NETs) are a combination of DNA fibers and granular enzymes, such as elastase and myeloperoxidase. In this study, we demonstrate that Candida albicans hyphal (CAH) cells and yeast (CAY) cells induce differential amounts, kinetics and mechanisms of NET release. CAH cells induced larger quantities of NET compared to CAY cells and can stimulate rapid NET formation up to 4 h of incubation. CAY cells are, also, able to induce rapid NET formation, but this ability was lost at 4 h. Both reactive oxygen species (ROS) and autophagy are implicated in NET induced by CAH and CAY cells, but with a time-different participation of these two mechanisms. In particular, in the early phase (15 min) CAH cells stimulate NET via autophagy, but not via ROS, while CAY cells induce NET via both autophagy and ROS. At 4 h, only CAH cells stimulate NET formation using autophagy as well as ROS. Finally, we demonstrate that NET release, in response to CAH cells, involves NF-κB activation and is strongly implicated in hyphal destruction. PMID:27375599

  14. Nucleotide receptor signaling in murine macrophages is linked to reactive oxygen species generation.

    PubMed

    Pfeiffer, Zachary A; Guerra, Alma N; Hill, Lindsay M; Gavala, Monica L; Prabhu, Usha; Aga, Mini; Hall, David J; Bertics, Paul J

    2007-05-15

    Macrophage activation is critical in the innate immune response and can be regulated by the nucleotide receptor P2X7. In this regard, P2X7 signaling is not well understood but has been implicated in controlling reactive oxygen species (ROS) generation by various leukocytes. Although ROS can contribute to microbial killing, the role of ROS in nucleotide-mediated cell signaling is unclear. In this study, we report that the P2X7 agonists ATP and 3'-O-(4-benzoyl) benzoic ATP (BzATP) stimulate ROS production by RAW 264.7 murine macrophages. These effects are potentiated in lipopolysaccharide-primed cells, demonstrating an important interaction between extracellular nucleotides and microbial products in ROS generation. In terms of nucleotide receptor specificity, RAW 264.7 macrophages that are deficient in P2X7 are greatly reduced in their capacity to generate ROS in response to BzATP treatment (both with and without LPS priming), thus supporting a role for P2X7 in this process. Because MAP kinase activation is key for nucleotide regulation of macrophage function, we also tested the hypothesis that P2X7-mediated MAP kinase activation is dependent on ROS production. We observed that BzATP stimulates MAP kinase (ERK1/ERK2, p38, and JNK1/JNK2) phosphorylation and that the antioxidants N-acetylcysteine and ascorbic acid strongly attenuate BzATP-mediated JNK1/JNK2 and p38 phosphorylation but only slightly reduce BzATP-induced ERK1/ERK2 phosphorylation. These studies reveal that P2X7 can contribute to macrophage ROS production, that this effect is potentiated upon lipopolysaccharide exposure, and that ROS are important participants in the extracellular nucleotide-mediated activation of several MAP kinase systems. PMID:17448897

  15. Generation of Reactive Oxygen Species from Silicon Nanowires

    PubMed Central

    Leonard, Stephen S; Cohen, Guy M; Kenyon, Allison J; Schwegler-Berry, Diane; Fix, Natalie R; Bangsaruntip, Sarunya; Roberts, Jenny R

    2014-01-01

    Processing and synthesis of purified nanomaterials of diverse composition, size, and properties is an evolving process. Studies have demonstrated that some nanomaterials have potential toxic effects and have led to toxicity research focusing on nanotoxicology. About two million workers will be employed in the field of nanotechnology over the next 10 years. The unknown effects of nanomaterials create a need for research and development of techniques to identify possible toxicity. Through a cooperative effort between National Institute for Occupational Safety and Health and IBM to address possible occupational exposures, silicon-based nanowires (SiNWs) were obtained for our study. These SiNWs are anisotropic filamentary crystals of silicon, synthesized by the vapor–liquid–solid method and used in bio-sensors, gas sensors, and field effect transistors. Reactive oxygen species (ROS) can be generated when organisms are exposed to a material causing cellular responses, such as lipid peroxidation, H2O2 production, and DNA damage. SiNWs were assessed using three different in vitro environments (H2O2, RAW 264.7 cells, and rat alveolar macrophages) for ROS generation and possible toxicity identification. We used electron spin resonance, analysis of lipid peroxidation, measurement of H2O2 production, and the comet assay to assess generation of ROS from SiNW and define possible mechanisms. Our results demonstrate that SiNWs do not appear to be significant generators of free radicals. PMID:25452695

  16. Khat (Catha edulis) generates reactive oxygen species and promotes hepatic cell apoptosis via MAPK activation.

    PubMed

    Abid, Morad Dirhem Naji; Chen, Juan; Xiang, Min; Zhou, Jie; Chen, Xiaoping; Gong, Feili

    2013-08-01

    A number of studies have suggested an association between khat (Catha edulis) chewing and acute liver lesions or chronic liver disease. However, little is known about the effects of khat on hepatic cells. In the current study, we investigated the mechanism behind khat-induced apoptosis in the L02 human hepatic cell line. We used cell growth inhibition assay, flow cytometry and Hoechst 33258 staining to measure hepatocyte apoptosis induced by khat. Western blot analysis was used to detect the expression levels of caspase-8 and -9, as well as those of Bax and Bcl-2. We also measured reactive oxygen species production. The results indicated that khat induced significant hepatocyte apoptosis in L02 cells. We found that khat activated caspase-8 and -9, upregulated Bax protein expression and downregulated Bcl-2 expression levels, which resulted in the coordination of apoptotic signals. Khat-induced hepatocyte apoptosis is primarily regulated through the sustained activation of the c-Jun NH2-terminal kinase (JNK) pathway and only partially via the extracellular signal-regulated kinase (ERK) cascade. Furthermore, the khat-induced reactive oxygen species (ROS) production and the activation of the ROS scavenger, N-acetyl-L-cysteine (NAC), attenuated the khat-induced activation of JNK and ERK. Our results demonstrate that khat triggers the generation of intracellular ROS and sequentially induces the sustainable activation of JNK, which in turn results in a decrease in cell viability and an increase in cell apoptosis. PMID:23708648

  17. Bioreductively Activated Reactive Oxygen Species (ROS) Generators as MRSA Inhibitors.

    PubMed

    Khodade, Vinayak S; Sharath Chandra, Mallojjala; Banerjee, Ankita; Lahiri, Surobhi; Pulipeta, Mallikarjuna; Rangarajan, Radha; Chakrapani, Harinath

    2014-07-10

    The number of cases of drug resistant Staphylococcus aureus infections is on the rise globally and new strategies to identify drug candidates with novel mechanisms of action are in urgent need. Here, we report the synthesis and evaluation of a series of benzo[b]phenanthridine-5,7,12(6H)-triones, which were designed based on redox-active natural products. We find that the in vitro inhibitory activity of 6-(prop-2-ynyl)benzo[b]phenanthridine-5,7,12(6H)-trione (1f) against methicillin-resistant Staphylococcus aureus (MRSA), including a panel of patient-derived strains, is comparable or better than vancomycin. We show that the lead compound generates reactive oxygen species (ROS) in the cell, contributing to its antibacterial activity. PMID:25050164

  18. Photosensitizing Nanoparticles and The Modulation of Reactive Oxygen Species generation

    NASA Astrophysics Data System (ADS)

    Tada, Dayane; Baptista, Mauricio

    2015-05-01

    The association of PhotoSensitizer (PS) molecules with nanoparticles (NPs) forming photosensitizing NPs, has emerged as a therapeutic strategy to improve PS tumor targeting, to protect PS from deactivation reactions and to enhance both PS solubility and circulation time. Since association with NPs usually alters PS photophysical and photochemical properties, photosensitizing NPs are an important tool to modulate reactive oxygen species (ROS) generation. Depending on the design of the photosensitizing NP, i.e., type of PS, the NP material and the method applied for the construction of the photosensitizing NP, the deactivation routes of the excited state can be controlled, allowing the generation of either singlet oxygen or other ROS. Controlling the type of generated ROS is desirable not only in biomedical applications, as in Photodynamic Therapy where the type of ROS affects therapeutic efficiency, but also in other technological relevant fields like energy conversion, where the electron and energy transfer processes are necessary to increase the efficiency of photoconversion cells. The current review highlights some of the recent developments in the design of Photosensitizing NPs aimed at modulating the primary photochemical events after light absorption.

  19. Quantitative assessment of reactive oxygen sonochemically generated by cavitation bubbles

    NASA Astrophysics Data System (ADS)

    Yasuda, Jun; Miyashita, Takuya; Taguchi, Kei; Yoshizawa, Shin; Umemura, Shin-ichiro

    2015-07-01

    Acoustic cavitation bubbles can induce not only a thermal bioeffect but also a chemical bioeffect. When cavitation bubbles collapse and oscillate violently, they produce reactive oxygen species (ROS) that cause irreversible changes to the tissue. A sonosensitizer can promote such ROS generation. A treatment method using a sonosensitizer is called sonodynamic treatment. Rose bengal (RB) is one of the sonosensitizers whose in vivo and in vitro studies have been reported. In sonodynamic treatment, it is important to produce ROS at a high efficiency. For the efficient generation of ROS, a triggered high-intensity focused ultrasound (HIFU) sequence has been proposed. In this study, cavitation bubbles were generated in a chamber where RB solution was sealed, and a high-speed camera captured the behavior of these cavitation bubbles. The amount of ROS was also quantified by a potassium iodide (KI) method and compared with high-speed camera pictures to investigate the effectiveness of the triggered HIFU sequence. As a result, ROS could be obtained efficiently by this sequence.

  20. Plasma-generated reactive oxygen species for biomedical applications

    NASA Astrophysics Data System (ADS)

    Sousa, J. S.; Hammer, M. U.; Winter, J.; Tresp, H.; Duennbier, M.; Iseni, S.; Martin, V.; Puech, V.; Weltmann, K. D.; Reuter, S.

    2012-10-01

    To get a better insight into the effects of reactive oxygen species (ROS) on cellular components, fundamental studies are essential to determine the nature and concentration of plasma-generated ROS, and the chemistry induced in biological liquids by those ROS. In this context, we have measured the absolute density of the main ROS created in three different atmospheric pressure plasma sources: two geometrically distinct RF-driven microplasma jets (μ-APPJ [1] and kinpen [2]), and an array of microcathode sustained discharges [3]. Optical diagnostics of the plasma volumes and effluent regions have been performed: UV absorption for O3 and IR emission for O2(a^1δ) [4]. High concentrations of both ROS have been obtained (10^14--10^17cm-3). The effect of different parameters, such as gas flows and mixtures and power coupled to the plasmas, has been studied. For plasma biomedicine, the determination of the reactive species present in plasma-treated liquids is of great importance. In this work, we focused on the measurement of the concentration of H2O2 and NOX radicals, generated in physiological solutions like NaCl and PBS.[4pt] [1] N. Knake et al., J. Phys. D: App. Phys. 41, 194006 (2008)[0pt] [2] K.D. Weltmann et al., Pure Appl. Chem. 82, 1223 (2010)[0pt] [3] J.S. Sousa et al., Appl. Phys. Lett. 97, 141502 (2010)[0pt] [4] J.S. Sousa et al., Appl. Phys. Lett. 93, 011502 (2008)

  1. Fabrication and biological evaluation of uniform extracellular matrix coatings on discontinuous photolithography generated micropallet arrays

    PubMed Central

    Gunn, Nicholas M.; Bachman, Mark; Li, Guann-Pyng; Nelson, Edward L.

    2010-01-01

    ABSTRACT/SYNOPSIS The recent identification of rare cell populations within tissues that are associated with specific biological behaviors, e.g., progenitor cells, has illuminated a limitation of current technologies to study such adherent cells directly from primary tissues. The micropallet array is a recently developed technology designed to address this limitation by virtue of its capacity to isolate and recover single adherent cells on individual micropallets. The capacity to apply this technology to primary tissues and cells with restricted growth characteristics, particularly adhesion requirements, is critically dependent upon the capacity to generate functional extracellular matrix (ECM) coatings. The discontinuous nature of the micropallet array surface provides specific constraints on the processes for generating the desired ECM coatings that are necessary to achieve the full functional capacity of the micropallet array. We have developed strategies, reported herein, to generate functional coatings with various ECM protein components: fibronectin, EHS tumor basement membrane extract, collagen, and laminin-5; confirmed by evaluation for rapid cellular adherence of four dissimilar cell types: fibroblast, breast epithelial, pancreatic epithelial, and myeloma. These findings are important for the dissemination and expanded use of micropallet arrays and similar microtechnologies requiring the integrated use of ECM protein coatings to promote cellular adherence. PMID:20648537

  2. Ascorbate and α-tocopherol differentially modulate reactive oxygen species generation by neutrophils in response to FcγR and TLR agonists.

    PubMed

    Chapple, Iain Lc; Matthews, John B; Wright, Helen J; Scott, Ann E; Griffiths, Helen R; Grant, Melissa M

    2013-01-01

    Periodontitis, a ubiquitous chronic inflammatory disease, is associated with reduced antioxidant defences and neutrophil hyperactivity in terms of reactive oxygen species (ROS) generation. Its phenotype is thus characterized by oxidative stress. We have determined the effect of antioxidant micronutrients ascorbate and α-tocopherol on neutrophil ROS generation. Peripheral neutrophils from periodontally-healthy individuals (n = 20) were challenged with phorbol myristate acetate, IgG-opsonised Staphylococcus aureus, Fusobacterium nucleatum or PBS in the presence and absence of micronutrients (50 µM). Total and extracellular ROS were measured by luminol and isoluminol chemiluminescence respectively. Total and extracellular unstimulated, baseline ROS generation was unaffected by α-tocopherol, but inhibited by ascorbate and a combination of both micronutrients. Fcγ-receptor (Fcγ-R)-stimulated total or extracellular ROS generation was not affected by the presence of individual micronutrients. However, the combination significantly reduced extracellular FcγR-stimulated ROS release. Neither micronutrient inhibited TLR-stimulated total ROS, but the combination caused inhibition. Ascorbate and the micronutrient combination, but not α-tocopherol, inhibited extracellular ROS release by TLR-stimulated cells. Such micronutrient effects in vivo could be beneficial in reducing collateral tissue damage in chronic inflammatory diseases, such as periodontitis, while retaining immune-mediated neutrophil function. PMID:22914919

  3. Plasma effects on the generation of reactive oxygen and nitrogen species in cancer cells in-vitro exposed by atmospheric pressure pulsed plasma jets

    NASA Astrophysics Data System (ADS)

    Kim, Sun Ja; Chung, T. H.

    2015-08-01

    Atmospheric pressure pulsed helium plasma jets are utilized for plasma-cell interactions. The effect of operating parameters such as applied voltage, pulse repetition frequency, and duty ratio on the generation of specific reactive oxygen and nitrogen species in gas and liquid phases and within cells is investigated. The apoptotic changes detected by terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick-end labeling assay in cells caused by plasma exposure are observed to correlate well with the levels of extracellular and intracellular reactive oxygen and nitrogen species.

  4. Reactive oxygen generated by Nox1 triggers the angiogenic switch

    PubMed Central

    Arbiser, Jack L.; Petros, John; Klafter, Robert; Govindajaran, Baskaran; McLaughlin, Elizabeth R.; Brown, Lawrence F.; Cohen, Cynthia; Moses, Marsha; Kilroy, Susan; Arnold, Rebecca S.; Lambeth, J. David

    2002-01-01

    The reactive oxygen-generating enzyme Nox1 transforms NIH 3T3 cells, rendering them highly tumorigenic and, as shown herein, also increases tumorigenicity of DU-145 prostate epithelial cells. Although Nox1 modestly stimulates cell division in both fibroblasts and epithelial cells, an increased mitogenic rate alone did not account fully for the marked tumorigenicity. Herein, we show that Nox1 is a potent trigger of the angiogenic switch, increasing the vascularity of tumors and inducing molecular markers of angiogenesis. Vascular endothelial growth factor (VEGF) mRNA becomes markedly up-regulated by Nox1 both in cultured cells and in tumors, and VEGF receptors (VEGFR1 and VEGFR2) are highly induced in vascular cells in Nox1-expressing tumors. Matrix metalloproteinase activity, another marker of the angiogenic switch, also is induced by Nox1. Nox1 induction of VEGF is eliminated by coexpression of catalase, indicating that hydrogen peroxide signals part of the switch to the angiogenic phenotype. PMID:11805326

  5. Reactive Transport Modeling of Acid Gas Generation and Condensation

    SciTech Connect

    G. Zhahg; N. Spycher; E. Sonnenthal; C. Steefel

    2005-01-25

    Pulvirenti et al. (2004) recently conducted a laboratory evaporation/condensation experiment on a synthetic solution of primarily calcium chloride. This solution represents one potential type of evaporated pore water at Yucca Mountain, Nevada, a site proposed for geologic storage of high-level nuclear waste. These authors reported that boiling this solution to near dryness (a concentration factor >75,000 relative to actual pore waters) leads to the generation of acid condensate (pH 4.5) presumably due to volatilization of HCl (and minor HF and/or HNO{sub 3}). To investigate the various processes taking place, including boiling, gas transport, and condensation, their experiment was simulated by modifying an existing multicomponent and multiphase reactive transport code (TOUGHREACT). This code was extended with a Pitzer ion-interaction model to deal with high ionic strength. The model of the experiment was set-up to capture the observed increase in boiling temperature (143 C at {approx}1 bar) resulting from high concentrations of dissolved salts (up to 8 m CaCl{sub 2}). The computed HCI fugacity ({approx} 10{sup -4} bars) generated by boiling under these conditions is not sufficient to lower the pH of the condensate (cooled to 80 and 25 C) down to observed values unless the H{sub 2}O mass fraction in gas is reduced below {approx}10%. This is because the condensate becomes progressively diluted by H{sub 2}O gas condensation. However, when the system is modeled to remove water vapor, the computed pH of instantaneous condensates decreases to {approx}1.7, consistent with the experiment (Figure 1). The results also show that the HCl fugacity increases, and calcite, gypsum, sylvite, halite, MgCl{sub 2}4H{sub 2}O and CaCl{sub 2} precipitate sequentially with increasing concentration factors.

  6. Generation of a novel transgenic rat model for tracing extracellular vesicles in body fluids.

    PubMed

    Yoshimura, Aya; Kawamata, Masaki; Yoshioka, Yusuke; Katsuda, Takeshi; Kikuchi, Hisae; Nagai, Yoshitaka; Adachi, Naoki; Numakawa, Tadahiro; Kunugi, Hiroshi; Ochiya, Takahiro; Tamai, Yoshitaka

    2016-01-01

    Extracellular vesicles (EVs) play an important role in the transfer of biomolecules between cells. To elucidate the intercellular transfer fate of EVs in vivo, we generated a new transgenic (Tg) rat model using green fluorescent protein (GFP)-tagged human CD63. CD63 protein is highly enriched on EV membranes via trafficking into late endosomes and is often used as an EV marker. The new Tg rat line in which human CD63-GFP is under control of the CAG promoter exhibited high expression of GFP in various body tissues. Exogenous human CD63-GFP was detected on EVs isolated from three body fluids of the Tg rats: blood serum, breast milk and amniotic fluid. In vitro culture allowed transfer of serum-derived CD63-GFP EVs into recipient rat embryonic fibroblasts, where the EVs localized in endocytic organelles. These results suggested that this Tg rat model should provide significant information for understanding the intercellular transfer and/or mother-child transfer of EVs in vivo. PMID:27539050

  7. Generation of a novel transgenic rat model for tracing extracellular vesicles in body fluids

    PubMed Central

    Yoshimura, Aya; Kawamata, Masaki; Yoshioka, Yusuke; Katsuda, Takeshi; Kikuchi, Hisae; Nagai, Yoshitaka; Adachi, Naoki; Numakawa, Tadahiro; Kunugi, Hiroshi; Ochiya, Takahiro; Tamai, Yoshitaka

    2016-01-01

    Extracellular vesicles (EVs) play an important role in the transfer of biomolecules between cells. To elucidate the intercellular transfer fate of EVs in vivo, we generated a new transgenic (Tg) rat model using green fluorescent protein (GFP)-tagged human CD63. CD63 protein is highly enriched on EV membranes via trafficking into late endosomes and is often used as an EV marker. The new Tg rat line in which human CD63-GFP is under control of the CAG promoter exhibited high expression of GFP in various body tissues. Exogenous human CD63-GFP was detected on EVs isolated from three body fluids of the Tg rats: blood serum, breast milk and amniotic fluid. In vitro culture allowed transfer of serum-derived CD63-GFP EVs into recipient rat embryonic fibroblasts, where the EVs localized in endocytic organelles. These results suggested that this Tg rat model should provide significant information for understanding the intercellular transfer and/or mother-child transfer of EVs in vivo. PMID:27539050

  8. Second harmonic generation microscopy analysis of extracellular matrix changes in human idiopathic pulmonary fibrosis

    PubMed Central

    Tilbury, Karissa; Hocker, James; Wen, Bruce L.; Sandbo, Nathan; Singh, Vikas; Campagnola, Paul J.

    2014-01-01

    Abstract. Patients with idiopathic fibrosis (IPF) have poor long-term survival as there are limited diagnostic/prognostic tools or successful therapies. Remodeling of the extracellular matrix (ECM) has been implicated in IPF progression; however, the structural consequences on the collagen architecture have not received considerable attention. Here, we demonstrate that second harmonic generation (SHG) and multiphoton fluorescence microscopy can quantitatively differentiate normal and IPF human tissues. For SHG analysis, we developed a classifier based on wavelet transforms, principle component analysis, and a K-nearest-neighbor algorithm to classify the specific alterations of the collagen structure observed in IPF tissues. The resulting ROC curves obtained by varying the numbers of principal components and nearest neighbors yielded accuracies of >95%. In contrast, simpler metrics based on SHG intensity and collagen coverage in the image provided little or no discrimination. We also characterized the change in the elastin/collagen balance by simultaneously measuring the elastin autofluorescence and SHG intensities and found that the IPF tissues were less elastic relative to collagen. This is consistent with known mechanical consequences of the disease. Understanding ECM remodeling in IPF via nonlinear optical microscopy may enhance our ability to differentiate patients with rapid and slow progression and, thus, provide better prognostic information. PMID:25134793

  9. Second harmonic generation microscopy analysis of extracellular matrix changes in human idiopathic pulmonary fibrosis.

    PubMed

    Tilbury, Karissa; Hocker, James; Wen, Bruce L; Sandbo, Nathan; Singh, Vikas; Campagnola, Paul J

    2014-08-01

    Patients with idiopathic fibrosis (IPF) have poor long-term survival as there are limited diagnostic/prognostic tools or successful therapies. Remodeling of the extracellular matrix (ECM) has been implicated in IPF progression; however, the structural consequences on the collagen architecture have not received considerable attention. Here, we demonstrate that second harmonic generation (SHG) and multiphoton fluorescence microscopy can quantitatively differentiate normal and IPF human tissues. For SHG analysis, we developed a classifier based on wavelet transforms, principle component analysis, and a K-nearest-neighbor algorithm to classify the specific alterations of the collagen structure observed in IPF tissues. The resulting ROC curves obtained by varying the numbers of principal components and nearest neighbors yielded accuracies of >95%. In contrast, simpler metrics based on SHG intensity and collagen coverage in the image provided little or no discrimination. We also characterized the change in the elastin/collagen balance by simultaneously measuring the elastin autofluorescence and SHG intensities and found that the IPF tissues were less elastic relative to collagen. This is consistent with known mechanical consequences of the disease. Understanding ECM remodeling in IPF via nonlinear optical microscopy may enhance our ability to differentiate patients with rapid and slow progression and, thus, provide better prognostic information. PMID:25134793

  10. Method for generating a highly reactive plasma for exhaust gas after treatment and enhanced catalyst reactivity

    SciTech Connect

    Whealton, John H.; Hanson, Gregory R.; Storey, John M.; Raridon, Richard J.; Armfield, Jeffrey S.; Bigelow, Timothy S.; Graves, Ronald L.

    2000-07-01

    This patent application describes a method and apparatus of exhaust gas remediation that enhance the reactivity of the material catalysts found within catalytic converters of cars, trucks, and power stations.

  11. Xanthohumol induces generation of reactive oxygen species and triggers apoptosis through inhibition of mitochondrial electron transfer chain complex I.

    PubMed

    Zhang, Bo; Chu, Wei; Wei, Peng; Liu, Ying; Wei, Taotao

    2015-12-01

    Xanthohumol is a prenylflavonoid extracted from hops (Humulus lupulus). It possesses anti-cancer and anti-inflammatory activities in vitro and in vivo, and offers therapeutic benefits for treatment of metabolic syndromes. However, the precise mechanisms underlying its pharmacological effects remain to be elucidated, together with its cellular target. Here, we provide evidence that xanthohumol directly interacts with the mitochondrial electron transfer chain complex I (NADH dehydrogenase), inhibits the oxidative phosphorylation, triggers the production of reactive oxygen species, and induces apoptosis. In addition, we show that as a result of the inhibition of the mitochondrial oxidative phosphorylation, xanthohumol exposure causes a rapid decrease of mitochondrial transmembrane potential. Furthermore, we showed that xanthohumol up-regulates the glycolytic capacity in cells, and thus compensates cellular ATP generation. Dissection of the multiple steps of aerobic respiration by extracellular flux assays revealed that xanthohumol specifically inhibits the activity of mitochondrial complex I, but had little effect on that of complex II, III and IV. Inhibition of complex I by xanthohumol caused the overproduction of reactive oxygen species, which are responsible for the induction of apoptosis in cancer cells. We also found that isoxanthohumol, the structural isomer of xanthohumol, is inactive to cells, suggesting that the reactive 2-hydroxyl group of xanthohumol is crucial for its targeting to the mitochondrial complex I. Together, the remodeling of cell metabolism revealed here has therapeutic potential for the use of xanthohumol. PMID:26453927

  12. Quantitative assessment of reactive oxygen species generation by cavitation incepted efficiently using nonlinear propagation effect

    NASA Astrophysics Data System (ADS)

    Yasuda, Jun; Yoshizawa, Shin; Umemura, Shin-ichiro

    2015-10-01

    Sonodynamic treatment is a treatment method that uses chemical bio-effect of cavitation bubbles. Reactive oxygen species that can kill cancerous tissue is induced by such chemical effect of cavitation bubbles and it is important to generate them efficiently for effective sonodynamic treatment. Cavitation cloud can be formed by an effect of nonlinear propagation and focus and in this study, it was experimentally investigated if cavitation cloud was useful for efficient generation of reactive oxygen species. As a result, it was demonstrated that cavitation cloud would be useful for efficient generation of reactive oxygen species.

  13. Two-Photon Photochemical Generation of Reactive Enediyne

    PubMed Central

    Poloukhtine, Andrei; Popik, Vladimir V.

    2008-01-01

    p-Quinoid cyclopropenone-containing enediyne precursor (1) has been synthesized by mono-cyclopropanation of one of the triple bonds in p-dimethoxy substituted 3,4-benzocyclodeca-1,5-diyne followed by oxidative demethylation. Cyclopropenone 1 is stable up to 90°C but readily produces reactive enediyne 2 upon single-photon (Φ300nm = 0.46) or two-photon (σ800 nm = 0.5 GM) photolysis. The photo-product 2 undergoes Bergman cyclization at 40°C with the life time of 88 h. PMID:16958537

  14. Reactive Carbonyl Species In Vivo: Generation and Dual Biological Effects

    PubMed Central

    Semchyshyn, Halyna M.

    2014-01-01

    Reactive carbonyls are widespread species in living organisms and mainly known for their damaging effects. The most abundant reactive carbonyl species (RCS) are derived from oxidation of carbohydrates, lipids, and amino acids. Chemical modification of proteins, nucleic acids, and aminophospholipids by RCS results in cytotoxicity and mutagenicity. In addition to their direct toxicity, modification of biomolecules by RCS gives rise to a multitude of adducts and cross links that are increasingly implicated in aging and pathology of a wide range of human diseases. Understanding of the relationship between metabolism of RCS and the development of pathological disorders and diseases may help to develop effective approaches to prevent a number of disorders and diseases. On the other hand, constant persistence of RCS in cells suggests that they perform some useful role in living organisms. The most beneficial effects of RCS are their establishment as regulators of cell signal transduction and gene expression. Since RCS can modulate different biological processes, new tools are required to decipher the precise mechanisms underlying dual effects of RCS. PMID:24634611

  15. Stratospheric ozone reactive chemicals generated by space launches worldwide

    SciTech Connect

    Brady, B.B.; Fournier, E.W.; Martin, L.R.; Cohen, R.B.

    1994-11-01

    We report quantities of inorganic chlorine compounds and aluminum oxide particles (Al203) deposited in the stratosphere and troposphere by solid rocket propelled launch vehicles. Totals are presented by launch vehicle type, summarized on an annual basis, and projected to the year 2010 using standard mission models. Data are given for Air Force, NASA (shuttle and expendable vehicles), the European Space Agency (ESA) (Ariane 5), and the Japanese Space Agency (H-1 and H-2). Whereas inorganic chlorine compounds released by solid rockets are directly related to stratospheric ozone depletion, much uncertainty surrounds reactivity of aluminum oxide particles. We also compare current and future effects of space launch on stratospheric ozone depletion with those of Ozone Depleting Chemicals (ODCs). As a baseline, we use projections of future ODC use by SMC, Air Force Materiel Command (AFMC), and the world. Relevant stratospheric chemistry is considered to make a legitimate comparison of ODC and solid rocket exhaust.

  16. Reactive oxygen species and hydrogen peroxide generation in cell migration

    PubMed Central

    Rudzka, Dominika A; Cameron, Jenifer M; Olson, Michael F

    2015-01-01

    Directional cell migration is a complex process that requires spatially and temporally co-ordinated regulation of actin cytoskeleton dynamics. In response to external cues, signals are transduced to elicit cytoskeletal responses. It has emerged that reactive oxygen species, including hydrogen peroxide, are important second messengers in pathways that influence the actin cytoskeleton, although the identities of key proteins regulated by hydrogen peroxide are largely unknown. We recently showed that oxidation of cofilin1 is elevated in migrating cells relative to stationary cells, and that the effect of this post-translational modification is to reduce cofilin1-actin binding and to inhibit filamentous-actin severing by cofilin1. These studies revealed that cofilin1 regulation by hydrogen peroxide contributes to directional cell migration, and established a template for discovering additional proteins that are regulated in an analogous manner. PMID:27066166

  17. Development of an Enhanced GenVARR™ (Generator Volt Ampere Reactive Reserve) System

    SciTech Connect

    Schatz, Joe E.

    2009-03-12

    Transmission system operators require near real time knowledge of reactive power capability to reliably operate large electric power transmission systems. Reactive power produced by, or capable of being produced by, a power generator is often estimated based on a series of mega volt amperes (MVA) capability curves for the generator. These curves indicate the ability of the generator to produce real and reactive power under a variety of conditions. In transmission planning and operating studies, it is often assumed, based on estimates for these capability curves, that the generator can provide its rated MVA capability output when needed for system stability However, generators may not always operate at levels depicted by the maximum MVA capability curve due to present constraints. Transmission system operators utilizing the generators’ capability curves for operation decisions regarding transmission system stability or for planning horizons may overestimate the capability of the generators to supply reactive power when required. Southern Company has enhanced GenVARR(TM), the system of plant data query, retrieval, and analysis and calculates the actual – not estimated -- remaining reactive power output capability. The remaining reactive output is considered spinning reserve and is displayed graphically to transmission control center and generating plant operators to identify real time VAR limits. GenVARR is capable of aggregating generators from a defined region, or other user selectable combinations, to represent the available reserves that the operators are specifically interested in. GenVARR(TM) has been put into live production operation and is expected to significantly improve the overall visibility of the reactive reserve capability of the system. This new version of GenVARR(TM) significantly enhances the products structure and performance, and enables links to other key transmission system operation tools.

  18. Method for generating a highly reactive plasma for exhaust gas aftertreatment and enhanced catalyst reactivity

    DOEpatents

    Whealton, John H.; Hanson, Gregory R.; Storey, John M.; Raridon, Richard J.; Armfield, Jeffrey S.; Bigelow, Timothy S.; Graves, Ronald L.

    2001-01-01

    A method for non-thermal plasma aftertreatment of exhaust gases the method comprising the steps of providing short risetime (about 40 ps), high frequency (about 5G hz), high power bursts of low-duty factor microwaves sufficient to generate a dielectric barrier discharge and passing a gas to treated through the discharge so as to cause dissociative reduction of the exhaust gases. The invention also includes a reactor for generating the non-thermal plasma.

  19. Generation of reactive oxygen radicals through bioactivation of mitomycin antibiotics.

    PubMed

    Pritsos, C A; Sartorelli, A C

    1986-07-01

    Mitomycin C (MC) is a naturally occurring anticancer agent which has been shown to be more cytotoxic to hypoxic tumor cells than to their aerobic counterparts. The mechanism of action of this agent is thought to involve biological reductive activation, to a species that alkylates DNA. A comparison of the cytotoxicity of MC to EMT6 tumor cells with that of the structural analogues porfiromycin (PM), N-(N',N'-dimethylaminomethylene)amine analogue of mitomycin C (BMY-25282), and N-(N',N'-dimethylaminomethylene)amine analogue of porfiromycin (BL-6783) has demonstrated that PM is considerably less cytotoxic to aerobic EMT6 cells than MC, whereas BMY-25282 and BL-6783 are significantly more toxic. The relative abilities of each of these compounds to generate oxygen free radicals following biological activation were measured. Tumor cell sonicates, reduced nicotinamide adenine dinucleotide phosphate-cytochrome c reductase, xanthine oxidase, and mitochondria were used as the biological reducing systems. All four mitomycin antibiotics produced oxygen radicals following biological reduction, a process that may account for the aerobic cytotoxicity of agents of this class. The generation of relative amounts of superoxide and hydroxyl radical were also measured in EMT6 cell sonicates. BMY-25282 and BL-6783 produced significantly greater quantities of oxygen free radicals with the EMT6 cell sonicate, reduced nicotinamide adenine dinucleotide phosphate-cytochrome c reductase, and mitochondria than did MC and PM. In contrast, BMY-25282 and BL-6783 did not generate detectable levels of free radicals in the presence of xanthine oxidase, whereas this enzyme was capable of generating free radicals with MC and PM as substrates. MC consistently produced greater amounts of free radicals than PM with all of the reducing systems. BMY-25282, BL-6783, and MC all generated hydroxyl radicals, while PM did not appear to form these radicals. The findings indicate that a correlation exists between

  20. Water-soluble fullerene materials for bioapplications: photoinduced reactive oxygen species generation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The photoinduced reactive oxygen species (ROS) generation from several water-soluble fullerenes was examined. Macromolecular or small molecular water-soluble fullerene complexes/derivatives were prepared and their 1O2 and O2•- generation abilities were evaluated by EPR spin-trapping methods. As a r...

  1. Extracellular respiration

    PubMed Central

    Gralnick, Jeffrey A.; Newman, Dianne K.

    2009-01-01

    Summary Although it has long been known that microbes can generate energy using diverse strategies, only recently has it become clear that a growing number involve electron transfer to or from extracellular substrates. The best-known example of what we will term ‘extracellular respiration’ is electron transfer between microbes and minerals, such as iron and manganese (hydr)oxides. This makes sense, given that these minerals are sparingly soluble. What is perhaps surprising, however, is that a number of substrates that might typically be classified as ‘soluble’ are also respired at the cell surface. There are several reasons why this might be the case: the substrate, in its ecological context, might be associated with a solid surface and thus effectively insoluble; the substrate, while soluble, might simply be too large to transport inside the cell; or the substrate, while benign in one redox state, might become toxic after it is metabolized. In this review, we discuss various examples of extracellular respiration, paying particular attention to what is known about the molecular mechanisms underlying these processes. As will become clear, much remains to be learned about the biochemistry, cell biology and regulation of extracellular respiration, making it a rich field of study for molecular microbiologists. PMID:17581115

  2. A flexible active and reactive power control strategy for a variable speed constant frequency generating system

    SciTech Connect

    Tang, Y.; Xu, L.

    1995-07-01

    Variable-speed constant-frequency generating systems are used in wind power, hydro power, aerospace, and naval power generations to enhance efficiency and reduce friction. In these applications, an attractive candidate is the slip power recovery system comprising of doubly excited induction machine or doubly excited brushless reluctance machine and PWM converters with a dc link. In this paper, a flexible active and reactive power control strategy is developed, such that the optimal torque-speed profile of the turbine can be followed and overall reactive power can be controlled, while the machine copper losses have been minimized. At the same time, harmonics injected into the power network has also been minimized. In this manner, the system can function as both a high-efficient power generator and a flexible reactive power compensator.

  3. Cardiac Extracellular Matrix Scaffold Generated Using Sarcomeric Disassembly and Antigen Removal.

    PubMed

    Papalamprou, Angela; Griffiths, Leigh G

    2016-04-01

    Xenogeneic cardiac extracellular matrix (cECM) scaffolds for reconstructive cardiac surgery applications have potential to overcome the limitations of current clinically utilized patch materials. A potentially ideal cECM scaffold would be immunologically acceptable while preserving the native cECM niche. Production of such a scaffold necessitates removal of cellular and antigenic components from cardiac tissue while preserving cECM structure/function properties. Existing decellularization methodologies predominantly utilize denaturing detergents which might irreversibly alter cECM material properties. To overcome potential deficiencies of current approaches, the effect of sarcomere relaxation and disassembly on resultant cECM scaffold cellularity was investigated. Additionally, the ability of sequential differential protein solubilization (antigen removal-AR) to reduce cECM scaffold antigenicity was examined. Sarcomeric relaxation and disassembly were necessary to achieve scaffold acellularity. All groups in which AR was employed displayed statistically significant decreases in residual antigenicity regardless of their degree of acellularity. AR combined with sarcomeric disassembly preserved structural, biochemical, mechanical and recellularization properties of the cECM scaffold. However, sodium dodecyl sulfate significantly altered cECM properties. This study demonstrates the importance of solubilizing cellular elements and antigenic components in a stepwise manner for production of a potentially ideal cECM scaffold and may have implications for future tissue engineering and regenerative medicine applications. PMID:26215309

  4. Evidence for extracellular, but not intracellular, generation of angiotensin II in the rat adrenal zona glomerulosa

    SciTech Connect

    Urata, H.; Khosla, M.C.; Bumpus, M.; Husain, A. )

    1988-11-01

    Based on the observation that high levels of renin and angiotensin II (Ang II) are found in the adrenal zona glomerulosa (ZG), it has been postulated that Ang II is formed intracellularly by the renin-converting enzyme cascade in this tissue. To test this hypothesis, the authors examined renin-angiotensin system components in subcellular fractions of the rat adrenal ZG. Renin activity and immunoreactive-Ang II (IR-Ang II) were observed in vesicular fractions but were not colocalized. In addition, angiotensinogen, angiotensin I, and converting enzyme were not observed in the renin or IR-Ang II-containing vesicular fractions. These data do not support the hypothesis that Ang II is formed intracellularly within the renin-containing vesicles of the ZG. Rather, since modulatable renin release from adrenal ZG slices was observed and renin activity was found in dense vesicular fractions (33-39% sucrose), it is likely that Ang II formation in the ZG is extracellular and initiated by the release of vesicular renin. In ZG lysomal fractions {sup 125}I-labeled Ang II was degraded to {sup 125}I-labeled des-(Phe{sup 8})Ang II. Since Ang II antibodies do not recognize des-(Phe{sup 8})Ang II, these finding explain why IR-Ang II in the ZG is due predominantly to Ang II and not to its C-terminal immunoreactive fragments.

  5. Dissolution and reactive oxygen species generation of inhaled cemented tungsten carbide particles in artificial human lung fluids

    NASA Astrophysics Data System (ADS)

    Stefaniak, A. B.; Leonard, S. S.; Hoover, M. D.; Virji, M. A.; Day, G. A.

    2009-02-01

    Inhalation of both cobalt (Co) and tungsten carbide (WC) particles is associated with development of hard metal lung disease (HMD) via generation of reactive oxygen species (ROS), whereas Co alone is sufficient to cause asthma via solubilization and hapten formation. We characterized bulk and aerodynamically size-separated W, WC, Co, spray dryer (pre-sintered), and chamfer grinder (post-sintered) powders. ROS generation was measured in the murine RAW 264.7 cell line using electron spin resonance. When dose was normalized to surface area, hydroxyl radical generation was independent of particle size, which suggests that particle surface chemistry may be an important exposure factor. Chamfer grinder particles generated the highest levels of ROS, consistent with the hypothesis that intimate contact of metals is important for ROS generation. In artificial extracellular lung fluid, alkylbenzyldimethylammonium chloride (ABDC), added to prevent mold growth during experiments, did not influence dissolution of Co (44.0±5.2 vs. 48.3±6.4%) however, dissolution was higher (p<0.05) in the absence of phosphate (62.0±5.4 vs. 48.3±6.4%). In artificial macrophage phagolysosomal fluid, dissolution of Co (36.2±10.4%) does not appear to be influenced (p=0.30) by the absence of glycine (29.8±2.1%), phosphate (39.6±8.6%), or ABDC (44.0±10.5%). These results aid in assessing and understanding Co and W inhalation dosimetry.

  6. Reactive uptake of HOCl to laboratory generated sea salt particles and nascent sea-spray aerosol

    NASA Astrophysics Data System (ADS)

    Campbell, N. R.; Ryder, O. S.; Bertram, T. H.

    2013-12-01

    Field observations suggest that the reactive uptake of HOCl on marine aerosol particles is an important source of chlorine radicals, particularly under low NOx conditions. However to date, laboratory measurements disagree on the magnitude of the reactive uptake coefficient for HOCl by a factor of 5 (γ(HOCl) ranges between 0.0004 and 0.0018), and there are no measurements of γ(HOCl) on nascent sea-spray aerosol. Here, we present measurements of the reactive uptake of HOCl to laboratory generated sodium chloride and sea-spray aerosol particles generated in a novel Marine Aerosol Reference Tank (MART), coupled to an entrained aerosol flow reactor and Chemical Ionization Mass Spectrometer (CIMS). Measurements of γ(HOCl) retrieved here are compared against those in the literature, and the role of organic coatings on nascent sea-spray aerosol is explored.

  7. The role of leukocyte-generated reactive metabolites in the pathogenesis of idiosyncratic drug reactions.

    PubMed

    Uetrecht, J P

    1992-01-01

    Evidence strongly suggests that many adverse drug reactions, including idiosyncratic drug reactions, involve reactive metabolites. Furthermore, certain functional groups, which are readily oxidized to reactive metabolites, are associated with a high incidence of adverse reactions. Most drugs can probably form reactive metabolites, but a simple comparison of covalent binding in vitro is unlikely to provide an accurate indication of the relative risk of a drug causing an idiosyncratic reaction because it does not provide an indication of how efficiently the metabolite is detoxified in vivo. In addition, the incidence and nature of adverse reactions associated with a given drug is probably determined in large measure by the location of reactive metabolite formation, as well as the chemical reactivity of the reactive metabolite. Such factors will determine which macromolecules the metabolites will bind to, and it is known that covalent binding to some proteins, such as those in the leukocyte membrane, is much more likely to lead to an immune-mediated reaction or other type of toxicity. Some reactive metabolites, such as acyl glucuronides, circulate freely and could lead to adverse reactions in almost any organ; however, most reactive metabolites have a short biological half-life, and although small amounts may escape the organ where they are formed, these metabolites are unlikely to reach sufficient concentrations to cause toxicity in other organs. Many idiosyncratic drug reactions involve leukocytes, especially agranulocytosis and drug-induced lupus. We and others have demonstrated that drugs can be metabolized by activated neutrophils and monocytes to reactive metabolites. The major reaction appears to be reaction with leukocyte-generated hypochlorous acid. Hypochlorous acid is quite reactive, and therefore it is likely that many other drugs will be found that are metabolized by activated leukocytes. Some neutrophil precursors contain myeloperoxidase and the NADPH

  8. The generation of hybrid electrospun nanofiber layer with extracellular matrix derived from human pluripotent stem cells, for regenerative medicine applications.

    PubMed

    Shtrichman, Ronit; Zeevi-Levin, Naama; Zaid, Rinat; Barak, Efrat; Fishman, Bettina; Ziskind, Anna; Shulman, Rita; Novak, Atara; Avrahami, Ron; Livne, Erella; Lowenstein, Lior; Zussman, Eyal; Itskovitz-Eldor, Joseph

    2014-10-01

    Extracellular matrix (ECM) has been utilized as a biological scaffold for tissue engineering applications in a variety of body systems, due to its bioactivity and biocompatibility. In the current study we developed a modified protocol for the efficient and reproducible derivation of mesenchymal progenitor cells (MPCs) from human embryonic stem cells as well as human induced pluripotent stem cells (hiPSCs) originating from hair follicle keratinocytes (HFKTs). ECM was produced from these MPCs and characterized in comparison to adipose mesenchymal stem cell ECM, demonstrating robust ECM generation by the excised HFKT-iPSC-MPCs. Exploiting the advantages of electrospinning we generated two types of electrospun biodegradable nanofiber layers (NFLs), fabricated from polycaprolactone (PCL) and poly(lactic-co-glycolic acid) (PLGA), which provide mechanical support for cell seeding and ECM generation. Elucidating the optimized decellularization treatment we were able to generate an available "off-the-shelf" implantable product (NFL-ECM). Using rat subcutaneous transplantation model we demonstrate that this stem-cell-derived construct is biocompatible and biodegradable and holds great potential for tissue regeneration applications. PMID:25185111

  9. ARSENIC SPECIES CAUSE RELEASE OF IRON FROM FERRITIN GENERATING REACTIVE OXYGEN SPECIES

    EPA Science Inventory

    ARSENIC SPECIES CAUSE RELEASE OF IRON FROM FERRITIN GENERATING REACTIVE OXYGEN SPECIES

    Arsenic-associated cancer (lung, bladder, skin, liver, kidney) remains a significant world- wide public health problem (e.g., Taiwan, Chile, Bangladesh, India, China and Thailand). Rece...

  10. Free IL-12p40 Monomer is a Polyfunctional Adapter for Generating Novel IL-12-Like Heterodimers Extracellularly

    PubMed Central

    Abdi, Kaveh; Singh, Nevil J.; Spooner, Eric; Kessler, Benedikt M.; Radaev, Sergei; Lantz, Larry; Xiao, Tsan Sam; Matzinger, Polly; Sun, Peter D.; Ploegh, Hidde L.

    2014-01-01

    IL-12p40 partners with the p35 and p19 polypeptides to generate the heterodimeric cytokines IL-12 and IL-23 respectively. These cytokines play critical and distinct roles in host defense. The assembly of these heterodimers is thought to take place within the cell, resulting in the secretion of fully functional cytokines. Although the p40 subunit alone can also be rapidly secreted in response to inflammatory signals, its biological significance remains unclear. Here, we show that the secreted p40 monomer can generate de novo IL-12-like activities by combining extracellulary with p35 released from other cells. Surprisingly, an unbiased proteomic analysis reveals multiple such extracellular binding partners for p40 in the serum of mice after an endotoxin challenge. We biochemically validate the binding of one of these novel partners—the CD5 antigen-like glycoprotein CD5L— to the p40 monomer. Nevertheless, the assembled p40-CD5L heterodimer does not recapitulate the biological activity of IL-12. These findings underscore the plasticity of secreted free p40 monomer, suggesting that p40 functions as an adapter which is able to generate multiple de novo composites in combination with other locally available polypeptide partners, post secretion. PMID:24821971

  11. New Aspects on the Structure of Neutrophil Extracellular Traps from Chronic Obstructive Pulmonary Disease and In Vitro Generation

    PubMed Central

    Krautgartner, Wolf-Dietrich; Klappacher, Michaela; Kofler, Barbara; Steinbacher, Peter; Vitkov, Ljubomir; Grabcanovic-Musija, Fikreta; Studnicka, Michael

    2014-01-01

    Polymorphonuclear neutrophils have in recent years attracted new attention due to their ability to release neutrophil extracellular traps (NETs). These web-like extracellular structures deriving from nuclear chromatin have been depicted in ambiguous roles between antimicrobial defence and host tissue damage. NETs consist of DNA strands of varying thickness and are decorated with microbicidal and cytotoxic proteins. Their principal structure has in recent years been characterised at molecular and ultrastructural levels but many features that are of direct relevance to cytotoxicity are still incompletely understood. These include the extent of chromatin decondensation during NET formation and the relative amounts and spatial distribution of the microbicidal components within the NET. In the present work, we analyse the structure of NETs found in induced sputum of patients with acutely exacerbated chronic obstructive pulmonary disease (COPD) using confocal laser microscopy and electron microscopy. In vitro induced NETs from human neutrophils serve for purposes of comparison and extended analysis of NET structure. Results demonstrate that COPD sputa are characterised by the pronounced presence of NETs and NETotic neutrophils. We provide new evidence that chromatin decondensation during NETosis is most extensive and generates substantial amounts of double-helix DNA in ‘beads-on-a-string’ conformation. New information is also presented on the abundance and location of neutrophil elastase (NE) and citrullinated histone H3 (citH3). NE occurs in high densities in nearly all non-fibrous constituents of the NETs while citH3 is much less abundant. We conclude from the results that (i) NETosis is an integral part of COPD pathology; this is relevant to all future research on the etiology and therapy of the disease; and that (ii) release of ‘beads-on-a-string’ DNA studded with non-citrullinated histones is a common feature of in vivo NETosis; this is of relevance to both

  12. Generation of reactive oxygen species by interaction between antioxidants used as food additive and metal ions.

    PubMed

    Iwasaki, Yusuke; Oda, Momoko; Tsukuda, Yuri; Nagamori, Yuki; Nakazawa, Hiroyuki; Ito, Rie; Saito, Koichi

    2014-01-01

    Food additives, such as preservatives, sweeteners, coloring agents, and flavoring agents, are widely used in food manufacturing. However, their combined effects on the human body are not known. The purpose of this study was to examine whether combinations of antioxidants and metal ions generate reactive oxygen species (ROS) under in vitro conditions using electron spin resonance (ESR). Among the metal ions examined, only iron and copper generated ROS in the presence of antioxidants. Moreover, certain phenolic antioxidants having pro-oxidant activity induced DNA oxidation and degradation via the generation of high levels of ROS in the presence of copper ion, resulting in complete degradation of DNA in vitro. PMID:25212818

  13. A novel mechanism of generating extracellular vesicles during apoptosis via a beads-on-a-string membrane structure

    PubMed Central

    Atkin-Smith, Georgia K.; Tixeira, Rochelle; Paone, Stephanie; Mathivanan, Suresh; Collins, Christine; Liem, Michael; Goodall, Katharine J.; Ravichandran, Kodi S.; Hulett, Mark D.; Poon, Ivan K.H.

    2015-01-01

    Disassembly of apoptotic cells into smaller fragments (a form of extracellular vesicle called apoptotic bodies) can facilitate removal of apoptotic debris and intercellular communication. However, the mechanism underpinning this process is unclear. While observing monocytes undergoing apoptosis by time-lapse microscopy, we discovered a new type of membrane protrusion that resembles a ‘beads-on-a-string' structure. Strikingly, the ‘beads' are frequently sheared off the ‘string' to form apoptotic bodies. Generation of apoptotic bodies via this mechanism can facilitate a sorting process and results in the exclusion of nuclear contents from apoptotic bodies. Mechanistically, generation of ‘beads-on-a-string' protrusion is controlled by the level of actomyosin contraction and apoptopodia formation. Furthermore, in an unbiased drug screen, we identified the ability of sertraline (an antidepressant) to block the formation of ‘beads-on-a-string' protrusions and apoptotic bodies. These data uncover a new mechanism of apoptotic body formation in monocytes and also compounds that can modulate this process. PMID:26074490

  14. Trace heavy metal ions promoted extracellular electron transfer and power generation by Shewanella in microbial fuel cells.

    PubMed

    Xu, Yu-Shang; Zheng, Tao; Yong, Xiao-Yu; Zhai, Dan-Dan; Si, Rong-Wei; Li, Bing; Yu, Yang-Yang; Yong, Yang-Chun

    2016-07-01

    Although microbial fuel cells (MFCs) is considered as one of the most promising technology for renewable energy harvesting, low power output still accounts one of the bottlenecks and limits its further development. In this work, it is found that Cu(2+) (0.1μgL(-1)-0.1mgL(-1)) or Cd(2+) (0.1μgL(-1)-1mgL(-1)) significantly improve the electricity generation in MFCs. The maximum power output achieved with trace level of Cu(2+) (∼6nM) or Cd(2+) (∼5nM) is 1.3 times and 1.6 times higher than that of the control, respectively. Further analysis verifies that addition of Cu(2+) or Cd(2+) effectively improves riboflavin production and bacteria attachment on the electrode, which enhances bacterial extracellular electron transfer (EET) in MFCs. These results unveil the mechanism for power output enhancement by Cu(2+) or Cd(2+) addition, and suggest that metal ion addition should be a promising strategy to enhance EET as well as power generation of MFCs. PMID:27038263

  15. Effect of fluticasone propionate on neutrophil chemotaxis, superoxide generation, and extracellular proteolytic activity in vitro.

    PubMed Central

    Llewellyn-Jones, C. G.; Hill, S. L.; Stockley, R. A.

    1994-01-01

    BACKGROUND--Corticosteroids are widely used in the treatment of many inflammatory conditions but the exact mode of action on neutrophil function is uncertain. Fluticasone propionate is a new topically active synthetic steroid which can be measured in body fluids and which undergoes first pass metabolism. METHODS--The effects of fluticasone propionate on the function of neutrophils isolated from normal, healthy control subjects and on the chemotactic activity of sputum sol phase were assessed. RESULTS--Preincubation of neutrophils with fluticasone propionate reduced the chemotactic response to 10(-8) mol/l F-Met-Leu-Phe (FMLP) and to a 1:5 dilution of sputum sol phase in a dose dependent manner. Furthermore, when fluticasone propionate was added to sputum from eight patients with stable chronic obstructive bronchitis the chemotactic activity of a 1:5 dilution of the sol phase fell from a mean (SE) value of 22.2 (1.21) cells/field to 19.6 (0.89), 17.1 (0.74), and 11.9 (0.6) cells field at 1 mumol/l, 10 mumol/l, and 100 mumol/l, respectively. In further experiments fluticasone propionate preincubated with neutrophils inhibited fibronectin degradation by resting cells and by cells stimulated by FMLP (15.2% inhibition of resting cells, 5.1% inhibition of stimulated cells with 1 mumol/l fluticasone propionate, 24% and 18.7% inhibition respectively at 100 mumol/l fluticasone propionate. Fluticasone propionate had no effect on generation of superoxide anion by resting or stimulated cells. CONCLUSIONS--These results indicate that fluticasone propionate has a direct suppressive effect on several aspects of neutrophil function and may suggest a role for this agent in the modulation of neutrophil mediated damage to connective tissue. PMID:8202875

  16. Silver nanoparticles rapidly induce atypical human neutrophil cell death by a process involving inflammatory caspases and reactive oxygen species and induce neutrophil extracellular traps release upon cell adhesion.

    PubMed

    Liz, Rafael; Simard, Jean-Christophe; Leonardi, Laurien Bruna Araújo; Girard, Denis

    2015-09-01

    Inflammation is one of the major toxic effects reported in response to in vitro or in vivo nanoparticle (NP) exposure. Among engineered NPs, silver nanoparticles (AgNPs) are very attractive for the development of therapeutic strategies, especially because of their antimicrobial properties. In humans, neutrophils, key players in inflammation, are the most abundant blood leukocytes that spontaneously undergo apoptosis, a central cell death mechanism regulating inflammation. The aim of this study was to evaluate the effect of AgNPs on neutrophil apoptosis. Transmission electronic microscopy reveals that AgNPs rapidly penetrate inside neutrophils. AgNPs induced atypical cell death where the cell volume increased and the cell surface expression of CD16 remained unaltered unlike apoptotic neutrophils where cell shrinkage and loss of CD16 are typically observed. The AgNP-induced atypical cell death is distinct from necrosis and reversed by a pancaspase inhibitor or by inhibitors of the inflammatory caspase-1 and caspase-4. In addition, AgNPs induced IL-1β production inhibited by caspase-1 and caspase-4 inhibitors and also induced caspase-1 activity. Reactive oxygen species (ROS) production was increased by AgNPs and the atypical cell death was inhibited by the antioxidant n-acetylcysteine. Under similar experimental conditions, adhesion of neutrophils leads to neutrophil extracellular trap (NET) release induced by AgNPs. However, this process was not reversed by caspase inhibitors. We conclude that AgNPs rapidly induced an atypical cell death in neutrophils by a mechanism involving caspase-1, -4 and ROS. However, in adherent neutrophils, AgNPs induced NET release and, therefore, are novel agents able to trigger NET release. PMID:26241783

  17. Generation of reactive oxidative species from thermal treatment of sugar solutions.

    PubMed

    Wang, Qingyang; Durand, Erwann; Elias, Ryan J; Tikekar, Rohan V

    2016-04-01

    Sugars, prominently fructose, have been shown to accelerate the degradation of food components during thermal treatment. Yet, the mechanism by which this occurs is not well understood. Fructose and glucose have been reported to undergo autoxidation to generate reactive oxidative species (ROS) under physiological conditions; however, information on ROS generation during thermal treatment is limited. We observed that hydrogen peroxide was generated during thermal treatment (up to 70 °C) of aqueous solutions of fructose and glucose (up to 10% w/v), with significantly higher concentrations observed in fructose solutions. The rate of generation of hydrogen peroxide increased with temperature, pH, oxygen concentration and the presence of phosphate buffer. Singlet oxygen was also detected in fructose and glucose solutions prepared in phosphate buffer. Results of this study indicated that fructose and glucose undergo oxidation during thermal treatment resulting in generation of ROS that may have deleterious effects on food components. PMID:26593495

  18. Reactive species in non-equilibrium atmospheric-pressure plasmas: Generation, transport, and biological effects

    NASA Astrophysics Data System (ADS)

    Lu, X.; Naidis, G. V.; Laroussi, M.; Reuter, S.; Graves, D. B.; Ostrikov, K.

    2016-05-01

    Non-equilibrium atmospheric-pressure plasmas have recently become a topical area of research owing to their diverse applications in health care and medicine, environmental remediation and pollution control, materials processing, electrochemistry, nanotechnology and other fields. This review focuses on the reactive electrons and ionic, atomic, molecular, and radical species that are produced in these plasmas and then transported from the point of generation to the point of interaction with the material, medium, living cells or tissues being processed. The most important mechanisms of generation and transport of the key species in the plasmas of atmospheric-pressure plasma jets and other non-equilibrium atmospheric-pressure plasmas are introduced and examined from the viewpoint of their applications in plasma hygiene and medicine and other relevant fields. Sophisticated high-precision, time-resolved plasma diagnostics approaches and techniques are presented and their applications to monitor the reactive species and plasma dynamics in the plasma jets and other discharges, both in the gas phase and during the plasma interaction with liquid media, are critically reviewed. The large amount of experimental data is supported by the theoretical models of reactive species generation and transport in the plasmas, surrounding gaseous environments, and plasma interaction with liquid media. These models are presented and their limitations are discussed. Special attention is paid to biological effects of the plasma-generated reactive oxygen and nitrogen (and some other) species in basic biological processes such as cell metabolism, proliferation, survival, etc. as well as plasma applications in bacterial inactivation, wound healing, cancer treatment and some others. Challenges and opportunities for theoretical and experimental research are discussed and the authors' vision for the emerging convergence trends across several disciplines and application domains is presented to

  19. Fibrinogen cleavage by the Streptococcus pyogenes extracellular cysteine protease and generation of antibodies that inhibit enzyme proteolytic activity.

    PubMed

    Matsuka, Y V; Pillai, S; Gubba, S; Musser, J M; Olmsted, S B

    1999-09-01

    The extracellular cysteine protease from Streptococcus pyogenes is a virulence factor that plays a significant role in host-pathogen interaction. Streptococcal protease is expressed as an inactive 40-kDa precursor that is autocatalytically converted into a 28-kDa mature (active) enzyme. Replacement of the single cysteine residue involved in formation of the enzyme active site with serine (C192S mutation) abolished detectable proteolytic activity and eliminated autocatalytic processing of zymogen to the mature form. In the present study, we investigated activity of the wild-type (wt) streptococcal protease toward human fibrinogen and bovine casein. The former is involved in blood coagulation, wound healing, and other aspects of hemostasis. Treatment with streptococcal protease resulted in degradation of the COOH-terminal region of fibrinogen alpha chain, indicating that fibrinogen may serve as an important substrate for this enzyme during the course of human infection. Polyclonal antibodies generated against recombinant 40- and 28-kDa (r40- and r28-kDa) forms of the C192S streptococcal protease mutant exhibited high enzyme-linked immunosorbent assay titers but demonstrated different inhibition activities toward proteolytic action of the wt enzyme. Activity of the wt protease was readily inhibited when the reaction was carried out in the presence of antibodies generated against r28-kDa C192S mutant. Antibodies produced against r40-kDa C192S mutant had no significant effect on proteolysis. These data suggest that the presence of the NH(2)-terminal prosegment prevents generation of functionally active antibodies and indicate that inhibition activity of antibodies most likely depends on their ability to bind the active-site region epitope(s) of the protein. PMID:10456870

  20. Fibrinogen Cleavage by the Streptococcus pyogenes Extracellular Cysteine Protease and Generation of Antibodies That Inhibit Enzyme Proteolytic Activity

    PubMed Central

    Matsuka, Yury V.; Pillai, Subramonia; Gubba, Siddeswar; Musser, James M.; Olmsted, Stephen B.

    1999-01-01

    The extracellular cysteine protease from Streptococcus pyogenes is a virulence factor that plays a significant role in host-pathogen interaction. Streptococcal protease is expressed as an inactive 40-kDa precursor that is autocatalytically converted into a 28-kDa mature (active) enzyme. Replacement of the single cysteine residue involved in formation of the enzyme active site with serine (C192S mutation) abolished detectable proteolytic activity and eliminated autocatalytic processing of zymogen to the mature form. In the present study, we investigated activity of the wild-type (wt) streptococcal protease toward human fibrinogen and bovine casein. The former is involved in blood coagulation, wound healing, and other aspects of hemostasis. Treatment with streptococcal protease resulted in degradation of the COOH-terminal region of fibrinogen α chain, indicating that fibrinogen may serve as an important substrate for this enzyme during the course of human infection. Polyclonal antibodies generated against recombinant 40- and 28-kDa (r40- and r28-kDa) forms of the C192S streptococcal protease mutant exhibited high enzyme-linked immunosorbent assay titers but demonstrated different inhibition activities toward proteolytic action of the wt enzyme. Activity of the wt protease was readily inhibited when the reaction was carried out in the presence of antibodies generated against r28-kDa C192S mutant. Antibodies produced against r40-kDa C192S mutant had no significant effect on proteolysis. These data suggest that the presence of the NH2-terminal prosegment prevents generation of functionally active antibodies and indicate that inhibition activity of antibodies most likely depends on their ability to bind the active-site region epitope(s) of the protein. PMID:10456870

  1. Deleting the Redundant TSH Receptor C-Peptide Region Permits Generation of the Conformationally Intact Extracellular Domain by Insect Cells.

    PubMed

    Chen, Chun-Rong; Salazar, Larry M; McLachlan, Sandra M; Rapoport, Basil

    2015-07-01

    The TSH receptor (TSHR) extracellular domain (ECD) comprises a N-terminal leucine-rich repeat domain and an hinge region (HR), the latter contributing to ligand binding and critical for receptor activation. The crystal structure of the leucine-rich repeat domain component has been solved, but previous attempts to generate conformationally intact complete ECD or the isolated HR component for structural analysis have failed. The TSHR HR contains a C-peptide segment that is removed during spontaneous TSHR intramolecular cleavage into disulfide linked A- and B-subunits. We hypothesized that deletion of the redundant C-peptide would overcome the obstacle to generating conformationally intact TSHR ECD protein. Indeed, lacking the C-peptide region, the TSHR ECD (termed ECD-D1) and the isolated HR (termed HR-D1) were secreted into medium of insect cells infected with baculoviruses coding for these modified proteins. The identities of TSHR ECD-D1 and HR-D1 were confirmed by ELISA and immunoblotting using TSHR-specific monoclonal antibodies. The TSHR-ECD-D1 in conditioned medium was folded correctly, as demonstrated by its ability to inhibit radiolabeled TSH binding to the TSH holoreceptor. The TSHR ECD-D1 purification was accomplished in a single step using a TSHR monoclonal antibody affinity column, whereas the HR-D1 required a multistep protocol with a low yield. In conclusion, we report a novel approach to generate the TSHR ECD, as well as the isolated HR in insect cells, the former in sufficient amounts for structural studies. However, such studies will require previous complexing of the ECD with a ligand such as TSH or a thyroid-stimulating antibody. PMID:25860033

  2. Generation of reactive oxygen species and radiation response in lymphocytes and tumor cells.

    PubMed

    Shankar, Bhavani; Kumar, S Santosh; Sainis, K B

    2003-10-01

    Several types of lymphoid and myeloid tumor cells are known to be relatively resistant to radiation-induced apoptosis compared to normal lymphocytes. The intracellular generation of reactive oxygen species was measured in irradiated spleen cells from C57BL/6 and BALB/c mice and murine tumor cells (EL-4 and P388) by flow cytometry using dichlorodihydrofluoresceindiacetate and dihydrorhodamine 123 as fluorescent probes. The amount of reactive oxygen species generated per cell was low in the tumor cells compared to spleen cells exposed to 1 to 10 Gy of gamma radiation. This could be due to the higher total antioxidant levels in tumor cells compared to normal cells. Further, the changes in mitochondrial membrane potential and cytoplasmic Ca2+ content were appreciable in lymphocytes even at a dose of 1 Gy. In EL-4 cells, no such changes were observed at any of the doses used. About 65% of spleen cells underwent apoptosis 24 h after 1 Gy irradiation. However, under the same conditions, EL-4 and P388 cells failed to undergo apoptosis, but they accumulated in G2/M phase. Thus the intrinsic radioresistance of tumor cells may be due to a decreased generation of reactive oxygen species after irradiation and down-regulation of the subsequent events leading to apoptosis. PMID:12968927

  3. Scavenging activity of "beta catechin" on reactive oxygen species generated by photosensitization of riboflavin.

    PubMed

    Kumari, M V; Yoneda, T; Hiramatsu, M

    1996-05-01

    "beta CATECHIN", a preparation containing green tea extract, ascorbic acid, sunflower seed extract, dunaliella carotene and natural vitamin E, has been designed as a model "universal antioxidant" that offers protection via its scavenging action on a wide range of free radicals, both water-soluble and fat-soluble. Reactive oxygen species like singlet oxygen, hydroxyl and superoxide radicals, are often generated in biological systems during photosensitized oxidation reactions. We report on the simultaneous effect of "beta CATECHIN" on active oxygen species generated during the photosensitized oxidation of riboflavin using 2,2,6,6-tetramethyl-4-piperidone (TMPD) as a "spin-trapping" agent. The intensities of the resulting stable nitroxide radical adduct, 2,2,6,6-tetramethyl-4-piperidone-1-oxyl (TEMPONE), were detected by electron spin resonance (ESR) spectroscopy. Results show simultaneous, nonspecific and complete scavenging action of reactive oxygen species generated in our in vitro model system by "beta CATECHIN". It is therefore suggested that "beta CATECHIN" could offer protection against free radical insult and in preventing cancer and other diseases that are mediated by reactive oxygen species. PMID:8739038

  4. TNFα-Induced Apoptosis Enabled by CCN1/CYR61: Pathways of Reactive Oxygen Species Generation and Cytochrome c Release

    PubMed Central

    Juric, Vladislava; Chen, Chih-Chiun; Lau, Lester F.

    2012-01-01

    Although TNFα is a strong inducer of apoptosis, its cytotoxicity in most normal cells in vitro requires blockade of NFκB signaling or inhibition of de novo protein synthesis, typically by the addition of cycloheximide. However, several members of CCN (CYR61/CTGF/NOV) family of extracellular matrix proteins enable TNFα-dependent apoptosis in vitro without inhibiting NFκB or de novo protein synthesis, and CCN1 (CYR61) is essential for optimal TNFα cytotoxicity in vivo. Previous studies showed that CCN1 unmasks the cytotoxicity of TNFα by binding integrins αvβ5, α6β1, and the cell surface heparan sulfate proteoglycan syndecan 4 to induce the accumulation of a high level of reactive oxygen species (ROS), leading to a biphasic activation of JNK necessary for apoptosis. Here we show for the first time that CCN1 interacts with the low density lipoprotein receptor-related protein 1 (LRP1) in a protein complex, and that binding to LRP1 is critical for CCN1-induced ROS generation and apoptotic synergism with TNFα. We also found that neutral sphingomyelinase 1 (nSMase1), which contributes to CCN1-induced ROS generation, is required for CCN1/TNFα-induced apoptosis. Furthermore, CCN1 promotes the activation of p53 and p38 MAPK, which mediate enhanced cytochrome c release to amplify the cytotoxicity of TNFα. By contrast, LRP1, nSMase1, p53, and p38 MAPK are not required when TNFα-dependent apoptosis is facilitated by the presence of cycloheximide, indicating that they function in the CCN1 signaling pathway that converges with TNFα-induced signaling events. Since CCN1/CYR61 is a physiological regulator of TNFα cytotoxicity at least in some contexts, these findings may reveal important mediators of TNFα-induced apoptosis in vivo and identify potential therapeutic targets for thwarting TNFα-dependent tissue damage. PMID:22363611

  5. Multilayer Heterojunction Anodes for Saline Wastewater Treatment: Design Strategies and Reactive Species Generation Mechanisms.

    PubMed

    Yang, Yang; Shin, Jieun; Jasper, Justin T; Hoffmann, Michael R

    2016-08-16

    Multilayer heterojunction SbSn/CoTi/Ir anodes, which consist of Ir0.7Ta0.3O2 bottom layers coated onto a titanium base, Co-TiO2 interlayers, and overcoated discrete Sb-SnO2 islands, were prepared by spray pyrolysis. The Ir0.7Ta0.3O2 bottom layer serves as an Ohmic contact to facilitate electron transfer from semiconductor layers to the Ti base. The Co-TiO2 interlayer and overcoated Sb-SnO2 islands enhance the evolution of reactive chlorine. The surficial Sb-SnO2 islands also serve as the reactive sites for free radical generation. Experiments coupled with computational kinetic simulations show that while ·OH and Cl· are initially produced on the SbSn/CoTi/Ir anode surface, the dominant radical formed in solution is the dichlorine radical anion, Cl2·(-). The steady-state concentration of reactive radicals is 10 orders of magnitude lower than that of reactive chlorine. The SbSn/CoTi/Ir anode was applied to electrochemically treat human wastewater. These test results show that COD and NH4(+) can be removed after 2 h of electrolysis with minimal energy consumption (370 kWh/kg COD and 383 kWh/kg NH4(+)). Although free radical species contribute to COD removal, anodes designed to enhance reactive chlorine production are more effective than those designed to enhance free radical production. PMID:27402194

  6. Prooxidant action of knipholone anthrone: copper dependent reactive oxygen species generation and DNA damage.

    PubMed

    Habtemariam, S; Dagne, E

    2009-07-01

    Knipholone (KP) and knipholone anthrone (KA) are natural 4-phenylanthraquinone structural analogues with established differential biological activities including in vitro antioxidant and cytotoxic properties. By using DNA damage as an experimental model, the comparative Cu(II)-dependent prooxidant action of these two compounds were studied. In the presence of Cu(II) ions, the antioxidant KA (3.1-200 microM) but not KP (6-384 microM) caused a concentration-dependent pBR322 plasmid DNA strand scission. The DNA damage induced by KA could be abolished by reactive oxygen species scavengers, glutathione and catalase as well as EDTA and a specific Cu(I) chelator bathocuproine disulfonic acid. In addition to Cu(II) chelating activity, KA readily reduces Cu(II) to Cu(I). Copper-dependent generation of reactive oxygen species and the subsequent macromolecular damage may be involved in the antimicrobial and cytotoxic activity of KA. PMID:19345716

  7. Comparison of stainless and mild steel welding fumes in generation of reactive oxygen species

    PubMed Central

    2010-01-01

    Background Welding fumes consist of a wide range of complex metal oxide particles which can be deposited in all regions of the respiratory tract. The welding aerosol is not homogeneous and is generated mostly from the electrode/wire. Over 390,000 welders were reported in the U.S. in 2008 while over 1 million full-time welders were working worldwide. Many health effects are presently under investigation from exposure to welding fumes. Welding fume pulmonary effects have been associated with bronchitis, metal fume fever, cancer and functional changes in the lung. Our investigation focused on the generation of free radicals and reactive oxygen species from stainless and mild steel welding fumes generated by a gas metal arc robotic welder. An inhalation exposure chamber located at NIOSH was used to collect the welding fume particles. Results Our results show that hydroxyl radicals (.OH) were generated from reactions with H2O2 and after exposure to cells. Catalase reduced the generation of .OH from exposed cells indicating the involvement of H2O2. The welding fume suspension also showed the ability to cause lipid peroxidation, effect O2 consumption, induce H2O2 generation in cells, and cause DNA damage. Conclusion Increase in oxidative damage observed in the cellular exposures correlated well with .OH generation in size and type of welding fumes, indicating the influence of metal type and transition state on radical production as well as associated damage. Our results demonstrate that both types of welding fumes are able to generate ROS and ROS-related damage over a range of particle sizes; however, the stainless steel fumes consistently showed a significantly higher reactivity and radical generation capacity. The chemical composition of the steel had a significant impact on the ROS generation capacity with the stainless steel containing Cr and Ni causing more damage than the mild steel. Our results suggest that welding fumes may cause acute lung injury. Since type of

  8. Secretoglobin 1A1 and 1A1A Differentially Regulate Neutrophil Reactive Oxygen Species Production, Phagocytosis and Extracellular Trap Formation

    PubMed Central

    Côté, Olivier; Clark, Mary Ellen; Viel, Laurent; Labbé, Geneviève; Seah, Stephen Y. K.; Khan, Meraj A.; Douda, David N.; Palaniyar, Nades; Bienzle, Dorothee

    2014-01-01

    Secretoglobin family 1A member 1 (SCGB 1A1) is a small protein mainly secreted by mucosal epithelial cells of the lungs and uterus. SCGB 1A1, also known as club (Clara) cell secretory protein, represents a major constituent of airway surface fluid. The protein has anti-inflammatory properties, and its concentration is reduced in equine recurrent airway obstruction (RAO) and human asthma. RAO is characterized by reversible airway obstruction, bronchoconstriction and neutrophilic inflammation. Direct effects of SCGB 1A1 on neutrophil functions are unknown. We have recently identified that the SCGB1A1 gene is triplicated in equids and gives rise to two distinct proteins. In this study we produced the endogenously expressed forms of SCGBs (SCGB 1A1 and 1A1A) as recombinant proteins, and analyzed their effects on reactive oxygen species production, phagocytosis, chemotaxis and neutrophil extracellular trap (NET) formation ex vivo. We further evaluated whether NETs are present in vivo in control and inflamed lungs. Our data show that SCGB 1A1A but not SCGB 1A1 increase neutrophil oxidative burst and phagocytosis; and that both proteins markedly reduce neutrophil chemotaxis. SCGB 1A1A reduced chemotaxis significantly more than SCGB 1A1. NET formation was significantly reduced in a time- and concentration-dependent manner by SCGB 1A1 and 1A1A. SCGB mRNA in bronchial biopsies, and protein concentration in bronchoalveolar lavage fluid, was lower in horses with RAO. NETs were present in bronchoalveolar lavage fluid from horses with exacerbated RAO, but not in fluid from horses with RAO in remission or in challenged healthy horses. These findings indicate that SCGB 1A1 and 1A1A have overlapping and diverging functions. Considering disparities in the relative abundance of SCGB 1A1 and 1A1A in airway secretions of animals with RAO suggests that these functional differences may contribute to the pathogenesis of RAO and other neutrophilic inflammatory lung diseases. PMID:24777050

  9. Hypoxia induces adipocyte differentiation of adipose-derived stem cells by triggering reactive oxygen species generation.

    PubMed

    Kim, Ji Hye; Kim, Seok-Ho; Song, Seung Yong; Kim, Won-Serk; Song, Sun U; Yi, TacGhee; Jeon, Myung-Shin; Chung, Hyung-Min; Xia, Ying; Sung, Jong-Hyuk

    2014-01-01

    Generation of reactive oxygen species (ROS) by NADPH oxidase 4 (Nox4) induces the proliferation and migration of adipose-derived stem cells (ASCs). However, the functional role of mitochondrial ROS (mtROS) generation in ASCs is unknown. Therefore, we have investigated whether hypoxia induces the differentiation of ASCs via ROS generation. We also have tried to identify the cellular mechanisms of ROS generation underlying adipocyte differentiation. Hypoxia (2%) and ROS generators, such as antimycin and rotenone, induced adipocyte differentiation, which was attenuated by an ROS scavenger. Although Nox4 generates ROS and regulates proliferation of ASCs, Nox4 inhibition or Nox4 silencing did not inhibit adipocyte differentiation; indeed fluorescence intensity of mito-SOX increased in hypoxia, and treatment with mito-CP, a mtROS scavenger, significantly reduced hypoxia-induced adipocyte differentiation. Phosphorylation of Akt and mTOR was induced by hypoxia, while inhibition of these molecules prevented adipocyte differentiation. Thus hypoxia induces adipocyte differentiation by mtROS generation, and the PI3K/Akt/mTOR pathway is involved. PMID:23956071

  10. Light Emitting Diode-Generated Blue Light Modulates Fibrosis Characteristics: Fibroblast Proliferation, Migration Speed, and Reactive Oxygen Species Generation

    PubMed Central

    Mamalis, Andrew; Garcha, Manveer; Jagdeo, Jared

    2016-01-01

    Background and Objective Blue light is part of the visible light spectrum that does not generate harmful DNA adducts associated with skin cancer and photoaging, and may represent a safer therapeutic modality for treatment of keloid scars and other fibrotic skin diseases. Our laboratory previously demonstrated that light-emitting diode (LED) red and infrared light inhibits proliferation of skin fibroblasts. Moreover, different wavelengths of light can produce different biological effects. Furthermore, the effects of LED blue light (LED-BL) on human skin fibroblasts are not well characterized. This study investigated the effects of LED-BL on human skin fibroblast proliferation, viability, migration speed, and reactive oxygen-species (ROS) generation. Methods and Materials Irradiation of adult human skin fibroblasts using commercially-available LED-BL panels was performed in vitro, and modulation of proliferation and viability was quantified using the trypan blue dye exclusion assay, migratory speed was assessed using time-lapse video microscopy, and intracellular ROS generation was measured using the dihydrorhodamine flow cytometry assay. Statistical differences between groups were determined by ANOVA and Student s t-test. Results Human skin fibroblasts treated with LED-BL fluences of 5, 30, 45, and 80 J/cm2 demonstrated statistically significant dose-dependent decreases in relative proliferation of 8.4%, 29.1%, 33.8%, 51.7%, and 55.1%, respectively, compared to temperature and environment matched bench control plates, respectively. LED-BL fluences of 5, 30, 45 and 80 J/cm2 decreased fibroblast migration speed to 95 ± 7.0% (p = 0.64), 81.3 ± 5.5% (p = 0.021), 48.5 ± 2.7% (p < 0.0001), and 32.3 ± 1.9% (p < 0.0001), respectively, relative to matched controls. LED fluences of 5, 10, 30, and 80 J/cm2 resulted in statistically significant increases in reactive oxygen species of 110.4%, 116.6%, 127.5%, and 130%, respectively, relative to bench controls. Conclusion At

  11. Preferential Extracellular Generation of the Active Parkinsonian Toxin MPP+ by Transporter-Independent Export of the Intermediate MPDP+

    PubMed Central

    Pape, Regina; Meiser, Johannes; Karreman, Christiaan; Strittmatter, Tobias; Odermatt, Meike; Cirri, Erica; Friemel, Anke; Ringwald, Markus; Pasquarelli, Noemi; Ferger, Boris; Brunner, Thomas; Marx, Andreas; Möller, Heiko M.; Hiller, Karsten; Leist, Marcel

    2015-01-01

    Abstract Aims: 1-Methyl-4-phenyl-tetrahydropyridine (MPTP) is among the most widely used neurotoxins for inducing experimental parkinsonism. MPTP causes parkinsonian symptoms in mice, primates, and humans by killing a subpopulation of dopaminergic neurons. Extrapolations of data obtained using MPTP-based parkinsonism models to human disease are common; however, the precise mechanism by which MPTP is converted into its active neurotoxic metabolite, 1-methyl-4-phenyl-pyridinium (MPP+), has not been fully elucidated. In this study, we aimed to address two unanswered questions related to MPTP toxicology: (1) Why are MPTP-converting astrocytes largely spared from toxicity? (2) How does MPP+ reach the extracellular space? Results: In MPTP-treated astrocytes, we discovered that the membrane-impermeable MPP+, which is generally assumed to be formed inside astrocytes, is almost exclusively detected outside of these cells. Instead of a transporter-mediated export, we found that the intermediate, 1-methyl-4-phenyl-2,3-dihydropyridinium (MPDP+), and/or its uncharged conjugate base passively diffused across cell membranes and that MPP+ was formed predominately by the extracellular oxidation of MPDP+ into MPP+. This nonenzymatic extracellular conversion of MPDP+ was promoted by O2, a more alkaline pH, and dopamine autoxidation products. Innovation and Conclusion: Our data indicate that MPTP metabolism is compartmentalized between intracellular and extracellular environments, explain the absence of toxicity in MPTP-converting astrocytes, and provide a rationale for the preferential formation of MPP+ in the extracellular space. The mechanism of transporter-independent extracellular MPP+ formation described here indicates that extracellular genesis of MPP+ from MPDP is a necessary prerequisite for the selective uptake of this toxin by catecholaminergic neurons. Antioxid. Redox Signal. 23, 1001–1016. PMID:26413876

  12. The analysis of a reactive hydromagnetic internal heat generating poiseuille fluid flow through a channel.

    PubMed

    Hassan, A R; Maritz, R

    2016-01-01

    In this paper, the analysis of a reactive hydromagnetic Poiseuille fluid flow under different chemical kinetics through a channel in the presence of a heat source is carried out. An exothermic reaction is assumed while the concentration of the material is neglected. The Adomian decomposition method together with Pade approximation technique are used to obtain the solutions of the governing nonlinear non-dimensional differential equations. Effects of various physical parameters on the velocity and temperature fields of the fluid flow are investigated. The entropy generation analysis, irreversibility distribution ratio, Bejan number and the conditions for thermal criticality for different chemical kinetics are also presented. PMID:27563527

  13. Electrical stimulation of human embryonic stem cells: cardiac differentiation and the generation of reactive oxygen species.

    PubMed

    Serena, Elena; Figallo, Elisa; Tandon, Nina; Cannizzaro, Christopher; Gerecht, Sharon; Elvassore, Nicola; Vunjak-Novakovic, Gordana

    2009-12-10

    Exogenous electric fields have been implied in cardiac differentiation of mouse embryonic stem cells and the generation of reactive oxygen species (ROS). In this work, we explored the effects of electrical field stimulation on ROS generation and cardiogenesis in embryoid bodies (EBs) derived from human embryonic stem cells (hESC, line H13), using a custom-built electrical stimulation bioreactor. Electrical properties of the bioreactor system were characterized by electrochemical impedance spectroscopy (EIS) and analysis of electrical currents. The effects of the electrode material (stainless steel, titanium-nitride-coated titanium, titanium), length of stimulus (1 and 90 s) and age of EBs at the onset of electrical stimulation (4 and 8 days) were investigated with respect to ROS generation. The amplitude of the applied electrical field was 1 V/mm. The highest rate of ROS generation was observed for stainless steel electrodes, for signal duration of 90 s and for 4-day-old EBs. Notably, comparable ROS generation was achieved by incubation of EBs with 1 nM H(2)O(2). Cardiac differentiation in these EBs was evidenced by spontaneous contractions, expression of troponin T and its sarcomeric organization. These results imply that electrical stimulation plays a role in cardiac differentiation of hESCs, through mechanisms associated with the intracellular generation of ROS. PMID:19720058

  14. Compensation for Harmonic Currents and Reactive Power in Wind Power Generation System using PWM Inverter

    NASA Astrophysics Data System (ADS)

    Shinohara, Katsuji; Shinhatsubo, Kurato; Iimori, Kenichi; Yamamoto, Kichiro; Saruban, Takamichi; Yamaemori, Takahiro

    In recent year, consciousness of environmental problems is enhancing, and the price of the electric power purchased by an electric power company is established expensive for the power plant utilizing the natural energy. So, the introduction of the wind power generation is promoted in Japan. Generally, squirrel-cage induction machines are widely used as a generator in wind power generation system because of its small size, lightweight and low-cost. However, the induction machines do not have a source of excitation. Thus, it causes the inrush currents and the instantaneous voltage drop when the generator is directly connected to a power grid. To reduce the inrush currents, an AC power regulator is used. Wind power generations are frequently connected to and disconnected from the power grid. However, when the inrush currents are reduced, harmonic currents are caused by phase control of the AC power regulator. And the phase control of AC power regulator cannot control the power factor. Therefore, we propose the use of the AC power regulator to compensate for the harmonic currents and reactive power in the wind power generation system, and demonstrate the validity of its system by simulated and experimental results.

  15. Complex coordinated extracellular metabolism: Acid phosphatases activate diluted human leukocyte proteins to generate energy flow as NADPH from purine nucleotide ribose.

    PubMed

    Hibbs, John B; Vavrin, Zdenek; Cox, James E

    2016-08-01

    Complex metabolism is thought to occur exclusively in the crowded intracellular environment. Here we report that diluted enzymes from lysed human leukocytes produce extracellular energy. Our findings involve two pathways: the purine nucleotide catabolic pathway and the pentose phosphate pathway, which function together to generate energy as NADPH. Glucose6P fuel for NADPH production is generated from structural ribose of purine ribonucleoside monophosphates, ADP, and ADP-ribose. NADPH drives glutathione reductase to reduce an oxidized glutathione disulfide-glutathione redox couple. Acid phosphatases initiate ribose5P salvage from purine ribonucleoside monophosphates, and transaldolase controls the direction of carbon chain flow through the nonoxidative branch of the pentose phosphate pathway. These metabolic control points are regulated by pH. Biologically, this energy conserving metabolism could function in perturbed extracellular spaces. PMID:26895212

  16. Complex coordinated extracellular metabolism: Acid phosphatases activate diluted human leukocyte proteins to generate energy flow as NADPH from purine nucleotide ribose

    PubMed Central

    Hibbs, John B.; Vavrin, Zdenek; Cox, James E.

    2016-01-01

    Complex metabolism is thought to occur exclusively in the crowded intracellular environment. Here we report that diluted enzymes from lysed human leukocytes produce extracellular energy. Our findings involve two pathways: the purine nucleotide catabolic pathway and the pentose phosphate pathway, which function together to generate energy as NADPH. Glucose6P fuel for NADPH production is generated from structural ribose of purine ribonucleoside monophosphates, ADP, and ADP-ribose. NADPH drives glutathione reductase to reduce an oxidized glutathione disulfide-glutathione redox couple. Acid phosphatases initiate ribose5P salvage from purine ribonucleoside monophosphates, and transaldolase controls the direction of carbon chain flow through the nonoxidative branch of the pentose phosphate pathway. These metabolic control points are regulated by pH. Biologically, this energy conserving metabolism could function in perturbed extracellular spaces. PMID:26895212

  17. Chemically reactive species in liquids generated by atmospheric-pressure plasmas and their roles in plasma medicine

    NASA Astrophysics Data System (ADS)

    Hamaguchi, Satoshi

    2013-07-01

    Plasmas whose gas temperatures are close to room temperature may be generated in ambient air or a gas at atmospheric pressure with the use of low-frequency high voltage or low-power radio-frequency (RF) or microwave power applied to electrodes. Such plasmas can serve as a powerful source of free radicals and/or chemically reactive species that arise from atoms and molecules of the ambient gas. Recently use of such plasmas for medical purposes has attracted much attention as they can be implemented in possible medical devices that can cause blood coagulation, heal wounds, facilitate angiogenesis, sterilize surgical devices as well as living tissues without harming healthy cells, and selectively inactivate cancer cells. Especially of interest among reactive species generated by atmospheric-pressure plasmas (APP) are reactive oxygen species (ROS) and reactive nitrogen species (RNS) that are generated in liquid phase. Since most living tissues and cells are immersed in liquids (such as blood or culture media), reactive species generated by APPs in the gas phase are transported to the liquid phase and possibly converted to different types of reactive species therein before causing some influence on the tissues or cells. In this study, the rate equations are solved to evaluate concentrations of various reactive species in pure water that are originated by plasma reactions in atmosphere and possible effects of such species (including ROS/RNS) on living tissues and cells are discussed.

  18. Chemically reactive species in liquids generated by atmospheric-pressure plasmas and their roles in plasma medicine

    SciTech Connect

    Hamaguchi, Satoshi

    2013-07-11

    Plasmas whose gas temperatures are close to room temperature may be generated in ambient air or a gas at atmospheric pressure with the use of low-frequency high voltage or low-power radio-frequency (RF) or microwave power applied to electrodes. Such plasmas can serve as a powerful source of free radicals and/or chemically reactive species that arise from atoms and molecules of the ambient gas. Recently use of such plasmas for medical purposes has attracted much attention as they can be implemented in possible medical devices that can cause blood coagulation, heal wounds, facilitate angiogenesis, sterilize surgical devices as well as living tissues without harming healthy cells, and selectively inactivate cancer cells. Especially of interest among reactive species generated by atmospheric-pressure plasmas (APP) are reactive oxygen species (ROS) and reactive nitrogen species (RNS) that are generated in liquid phase. Since most living tissues and cells are immersed in liquids (such as blood or culture media), reactive species generated by APPs in the gas phase are transported to the liquid phase and possibly converted to different types of reactive species therein before causing some influence on the tissues or cells. In this study, the rate equations are solved to evaluate concentrations of various reactive species in pure water that are originated by plasma reactions in atmosphere and possible effects of such species (including ROS/RNS) on living tissues and cells are discussed.

  19. Symbiotic lactobacilli stimulate gut epithelial proliferation via Nox-mediated generation of reactive oxygen species

    PubMed Central

    Jones, Rheinallt M; Luo, Liping; Ardita, Courtney S; Richardson, Arena N; Kwon, Young Man; Mercante, Jeffrey W; Alam, Ashfaqul; Gates, Cymone L; Wu, Huixia; Swanson, Phillip A; Lambeth, J David; Denning, Patricia W; Neish, Andrew S

    2013-01-01

    The resident prokaryotic microbiota of the metazoan gut elicits profound effects on the growth and development of the intestine. However, the molecular mechanisms of symbiotic prokaryotic–eukaryotic cross-talk in the gut are largely unknown. It is increasingly recognized that physiologically generated reactive oxygen species (ROS) function as signalling secondary messengers that influence cellular proliferation and differentiation in a variety of biological systems. Here, we report that commensal bacteria, particularly members of the genus Lactobacillus, can stimulate NADPH oxidase 1 (Nox1)-dependent ROS generation and consequent cellular proliferation in intestinal stem cells upon initial ingestion into the murine or Drosophila intestine. Our data identify and highlight a highly conserved mechanism that symbiotic microorganisms utilize in eukaryotic growth and development. Additionally, the work suggests that specific redox-mediated functions may be assigned to specific bacterial taxa and may contribute to the identification of microbes with probiotic potential. PMID:24141879

  20. UVB dependence of quantum dot reactive oxygen species generation in common skin cell models

    PubMed Central

    MORTENSEN, LUKE J.; FAULKNOR, RENEA; RAVICHANDRAN, SUPRIYA; ZHENG, HONG; DELOUISE, LISA A.

    2015-01-01

    Studies have shown that UVB can slightly increase the penetration of nanoparticles through skin and significantly alter skin cell biology, thus it is important to understand if and how UVB may impact subsequent nanoparticle skin cell interactions. The research presented herein evaluates the effect of UVB on quantum dot (QD) uptake and reactive oxygen species (ROS) generation in primary keratinocytes, primary melanocytes, and related cell lines. QD exposure induced cell type dependent ROS responses increased by pre-exposing cells to UVB and correlated with the level of QD uptake. Our results suggest that keratinocytes may be at greater risk for QD induced ROS generation than melanocytes, and raise awareness about the differential cellular effects that topically applied nanomaterials may have on UVB exposed skin. PMID:26485933

  1. UVB Dependence of Quantum Dot Reactive Oxygen Species Generation in Common Skin Cell Models.

    PubMed

    Mortensen, Luke J; Faulknor, Renea; Ravichandran, Supriya; Zheng, Hong; DeLouise, Lisa A

    2015-09-01

    Studies have shown that UVB can slightly increase the penetration of nanoparticles through skin and significantly alter skin cell biology, thus it is important to understand if and how UVB may impact subsequent nanoparticle skin cell interactions. The research presented herein evaluates the effect of UVB on quantum dot (QD) uptake and reactive oxygen species (ROS) generation in primary keratinocytes, primary melanocytes, and related cell lines. QD exposure induced cell type dependent ROS responses increased by pre-exposing cells to UVB and correlated with the level of QD uptake. Our results suggest that keratinocytes may be at greater risk for QD induced ROS generation than melanocytes, and raise awareness about the differential cellular effects that topically applied nanomaterials may have on UVB exposed skin. PMID:26485933

  2. Berberine-induced apoptosis in human prostate cancer cells is initiated by reactive oxygen species generation

    SciTech Connect

    Meeran, Syed M.; Katiyar, Suchitra; Katiyar, Santosh K.

    2008-05-15

    Phytochemicals show promise as potential chemopreventive or chemotherapeutic agents against various cancers. Here we report the chemotherapeutic effects of berberine, a phytochemical, on human prostate cancer cells. The treatment of human prostate cancer cells (PC-3) with berberine induced dose-dependent apoptosis but this effect of berberine was not seen in non-neoplastic human prostate epithelial cells (PWR-1E). Berberine-induced apoptosis was associated with the disruption of the mitochondrial membrane potential, release of apoptogenic molecules (cytochrome c and Smac/DIABLO) from mitochondria and cleavage of caspase-9,-3 and PARP proteins. This effect of berberine on prostate cancer cells was initiated by the generation of reactive oxygen species (ROS) irrespective of their androgen responsiveness, and the generation of ROS was through the increased induction of xanthine oxidase. Treatment of cells with allopurinol, an inhibitor of xanthine oxidase, inhibited berberine-induced oxidative stress in cancer cells. Berberine-induced apoptosis was blocked in the presence of antioxidant, N-acetylcysteine, through the prevention of disruption of mitochondrial membrane potential and subsequently release of cytochrome c and Smac/DIABLO. In conclusion, the present study reveals that the berberine-mediated cell death of human prostate cancer cells is regulated by reactive oxygen species, and therefore suggests that berberine may be considered for further studies as a promising therapeutic candidate for prostate cancer.

  3. Controllable generation of reactive oxygen species by femtosecond-laser irradiation

    NASA Astrophysics Data System (ADS)

    Yan, Wei; He, Hao; Wang, Yintao; Wang, Yisen; Hu, Minglie; Wang, Chingyue

    2014-02-01

    Femtosecond lasers have been advancing Biophotonics research in the past two decades with multiphoton microscopy, microsurgery, and photodynamic therapy. Nevertheless, laser irradiation is identified to bring photodamage to cells via reactive oxygen species (ROS) generation with unclear mechanism. Meanwhile, currently in biological researches, there is no effective method to provide controllable ROS production precisely, which originally is leaked from mitochondria during respiration and plays a key role in a lot of important cellular processes and cellular signaling pathways. In this study, we show the process of how the tightly focused femtosecond-laser induces ROS generation solely in mitochondria at the very beginning and then release to cytosol if the stimulus is intense enough. At certain weak power levels, the laser pulses induce merely moderate Ca2+ release but this is necessary for the laser to generate ROS in mitochondria. Cellular original ROS are also involved with a small contribution. When the power is above a threshold, ROS are then released to cytosol, indicating photodamage overwhelming cellular repair ability. The mechanisms in those two cases are quite different. Those results clarify parts of the mechanism in laser-induced ROS generation. Hence, it is possible to further this optical scheme to provide controllable ROS generation for ROS-related biological researches including mitochondrial diseases and aging.

  4. Controllable generation of reactive oxygen species by femtosecond-laser irradiation

    SciTech Connect

    Yan, Wei; He, Hao Wang, Yintao; Wang, Yisen; Hu, Minglie; Wang, Chingyue

    2014-02-24

    Femtosecond lasers have been advancing Biophotonics research in the past two decades with multiphoton microscopy, microsurgery, and photodynamic therapy. Nevertheless, laser irradiation is identified to bring photodamage to cells via reactive oxygen species (ROS) generation with unclear mechanism. Meanwhile, currently in biological researches, there is no effective method to provide controllable ROS production precisely, which originally is leaked from mitochondria during respiration and plays a key role in a lot of important cellular processes and cellular signaling pathways. In this study, we show the process of how the tightly focused femtosecond-laser induces ROS generation solely in mitochondria at the very beginning and then release to cytosol if the stimulus is intense enough. At certain weak power levels, the laser pulses induce merely moderate Ca{sup 2+} release but this is necessary for the laser to generate ROS in mitochondria. Cellular original ROS are also involved with a small contribution. When the power is above a threshold, ROS are then released to cytosol, indicating photodamage overwhelming cellular repair ability. The mechanisms in those two cases are quite different. Those results clarify parts of the mechanism in laser-induced ROS generation. Hence, it is possible to further this optical scheme to provide controllable ROS generation for ROS-related biological researches including mitochondrial diseases and aging.

  5. Photochemistry of Dissolved Black Carbon Released from Biochar: Reactive Oxygen Species Generation and Phototransformation.

    PubMed

    Fu, Heyun; Liu, Huiting; Mao, Jingdong; Chu, Wenying; Li, Qilin; Alvarez, Pedro J J; Qu, Xiaolei; Zhu, Dongqiang

    2016-02-01

    Dissolved black carbon (BC) released from biochar can be one of the more photoactive components in the dissolved organic matter (DOM) pool. Dissolved BC was mainly composed of aliphatics and aromatics substituted by aromatic C-O and carboxyl/ester/quinone moieties as determined by solid-state nuclear magnetic resonance. It underwent 56% loss of absorbance at 254 nm, almost complete loss of fluorescence, and 30% mineralization during a 169 h simulated sunlight exposure. Photoreactions preferentially targeted aromatic and methyl moieties, generating CH2/CH/C and carboxyl/ester/quinone functional groups. During irradiation, dissolved BC generated reactive oxygen species (ROS) including singlet oxygen and superoxide. The apparent quantum yield of singlet oxygen was 4.07 ± 0.19%, 2-3 fold higher than many well-studied DOM. Carbonyl-containing structures other than aromatic ketones were involved in the singlet oxygen sensitization. The generation of superoxide apparently depended on electron transfer reactions mediated by silica minerals in dissolved BC, in which phenolic structures served as electron donors. Self-generated ROS played an important role in the phototransformation. Photobleaching of dissolved BC decreased its ability to further generate ROS due to lower light absorption. These findings have significant implications on the environmental fate of dissolved BC and that of priority pollutants. PMID:26717492

  6. Autophagy-related Gene 7 (ATG7) and Reactive Oxygen Species/Extracellular Signal-regulated Kinase Regulate Tetrandrine-induced Autophagy in Human Hepatocellular Carcinoma*

    PubMed Central

    Gong, Ke; Chen, Chao; Zhan, Yao; Chen, Yan; Huang, Zebo; Li, Wenhua

    2012-01-01

    Tetrandrine, a bisbenzylisoquinoline alkaloid isolated from the broadly used Chinese medicinal herb Stephaniae tetrandrae, exhibits potent antitumor effects and has the potential to be used as a cancer chemotherapeutic agent. We previously reported that high concentrations of tetrandrine induce apoptosis in liver cancer cells. Here, we found that in human hepatocellular carcinoma (HCC) cells, a low dose of tetrandrine (5 μm) induced the expression of LC3-II, resulted in the formation of acidic autophagolysosome vacuoles (AVOs), and caused a punctate fluorescence pattern with the GFP-LC3 protein, which all are markers for cellular autophagy. Tetrandrine induced the production of intracellular reactive oxygen species (ROS), and treatment with ROS scavengers significantly abrogated the tetrandrine-induced autophagy. These results suggest that the generation of ROS plays an important role in promoting tetrandrine-induced autophagy. Tetrandrine-induced mitochondrial dysfunction resulted in ROS accumulation and autophagy. ROS generation activated the ERK MAP kinase, and the ERK signaling pathway at least partially contributed to tetrandrine-induced autophagy in HCC cells. Moreover, we found that tetrandrine transcriptionally regulated the expression of autophagy related gene 7 (ATG7), which promoted tetrandrine-induced autophagy. In addition to in vitro studies, similar results were also observed in vivo, where tetrandrine caused the accumulation of ROS and induced cell autophagy in a tumor xenograft model. Interestingly, tetrandrine treatment also induced autophagy in a ROS-dependent manner in C. elegans muscle cells. Therefore, these findings suggest that tetrandrine is a potent autophagy agonist and may be a promising clinical chemotherapeutic agent. PMID:22927446

  7. No evidence for role of extracellular choline-acetyltransferase in generation of gamma oscillations in rat hippocampal slices in vitro.

    PubMed

    Hollnagel, J O; ul Haq, R; Behrens, C J; Maslarova, A; Mody, I; Heinemann, U

    2015-01-22

    Acetylcholine (ACh) is well known to induce persistent γ-oscillations in the hippocampus when applied together with physostigmine, an inhibitor of the ACh degrading enzyme acetylcholinesterase (AChE). Here we report that physostigmine alone can also dose-dependently induce γ-oscillations in rat hippocampal slices. We hypothesized that this effect was due to the presence of choline in the extracellular space and that this choline is taken up into cholinergic fibers where it is converted to ACh by the enzyme choline-acetyltransferase (ChAT). Release of ACh from cholinergic fibers in turn may then induce γ-oscillations. We therefore tested the effects of the choline uptake inhibitor hemicholinium-3 (HC-3) on persistent γ-oscillations either induced by physostigmine alone or by co-application of ACh and physostigmine. We found that HC-3 itself did not induce γ-oscillations and also did not prevent physostigmine-induced γ-oscillation while washout of physostigmine and ACh-induced γ-oscillations was accelerated. It was recently reported that ChAT might also be present in the extracellular space (Vijayaraghavan et al., 2013). Here we show that the effect of physostigmine was prevented by the ChAT inhibitor (2-benzoylethyl)-trimethylammonium iodide (BETA) which could indicate extracellular synthesis of ACh. However, when we tested for effects of extracellularly applied acetyl-CoA, a substrate of ChAT for synthesis of ACh, physostigmine-induced γ-oscillations were attenuated. Together, these findings do not support the idea that ACh can be synthesized by an extracellularly located ChAT. PMID:25453770

  8. Lactobacillus rhamnosus blocks inflammatory signaling in vivo via reactive oxygen species generation.

    PubMed

    Lin, Patricia W; Myers, Loren E S; Ray, Laurie; Song, Shuh-Chyung; Nasr, Tala R; Berardinelli, Andrew J; Kundu, Kousik; Murthy, Niren; Hansen, Jason M; Neish, Andrew S

    2009-10-15

    Uncontrolled inflammatory responses in the immature gut may play a role in the pathogenesis of many intestinal inflammatory syndromes that present in newborns or children, such as necrotizing enterocolitis (NEC), idiopathic inflammatory bowel diseases (IBD), or infectious enteritis. Consistent with previous reports that murine intestinal function matures over the first 3 weeks of life, we show that inflammatory signaling in the neonatal mouse gut increases during postnatal maturation, with peak responses occurring at 2-3 weeks. Probiotic bacteria can block inflammatory responses in cultured epithelia by inducing the generation of reactive oxygen species (ROS), which inhibit NF-kappaB activation through oxidative inactivation of the key regulatory enzyme Ubc12. We now report for the first time that the probiotic Lactobacillus rhamnosus GG (LGG) can induce ROS generation in intestinal epithelia in vitro and in vivo. Intestines from immature mice gavage fed LGG exhibited increased GSH oxidation and cullin-1 deneddylation, reflecting local ROS generation and its resultant Ubc12 inactivation, respectively. Furthermore, prefeeding LGG prevented TNF-alpha-induced intestinal NF-kappaB activation. These studies indicate that LGG can reduce inflammatory signaling in immature intestines by inducing local ROS generation and may be a mechanism by which probiotic bacteria can prevent NEC in premature infants or reduce the severity of IBD in children. PMID:19660542

  9. Redox cycling and generation of reactive oxygen species in commercial infant formulas.

    PubMed

    Boatright, William L; Crum, Andrea D

    2016-04-01

    Three nationally prominent commercial powdered infant formulas generated hydrogen peroxide, ranging from 10.46 to 11.62 μM, when prepared according to the manufacturer's instructions. Treating infant formulas with the chelating agent diethylene triamine pentaacetic acid (DTPA) significantly reduced H2O2 generation. In contrast, the addition of disodium ethylenediaminetetraacetic acid (EDTA) elevated the level of H2O2 generated in the same infant formulas by approximately 3- to 4-fold above the untreated infant formulas. The infant formulas contained ascorbate radicals ranging from about 138 nM to 40 nM. Treatment with catalase reduced the ascorbate radical contents by as much as 67%. Treatment with DTPA further reduced ascorbate radical signals to below quantifiable levels in most samples, further implicating the involvement of transition metal redox cycling in reactive oxygen species (ROS) formation. Supportive evidence of the generation of ROS is provided using luminol-enhanced luminescence (LEL) in both model mixtures of ascorbic acid and in commercial infant formulas. PMID:26593482

  10. Impact of plasma jet vacuum ultraviolet radiation on reactive oxygen species generation in bio-relevant liquids

    NASA Astrophysics Data System (ADS)

    Jablonowski, H.; Bussiahn, R.; Hammer, M. U.; Weltmann, K.-D.; von Woedtke, Th.; Reuter, S.

    2015-12-01

    Plasma medicine utilizes the combined interaction of plasma produced reactive components. These are reactive atoms, molecules, ions, metastable species, and radiation. Here, ultraviolet (UV, 100-400 nm) and, in particular, vacuum ultraviolet (VUV, 10-200 nm) radiation generated by an atmospheric pressure argon plasma jet were investigated regarding plasma emission, absorption in a humidified atmosphere and in solutions relevant for plasma medicine. The energy absorption was obtained for simple solutions like distilled water (dH2O) or ultrapure water and sodium chloride (NaCl) solution as well as for more complex ones, for example, Rosewell Park Memorial Institute (RPMI 1640) cell culture media. As moderate stable reactive oxygen species, hydrogen peroxide (H2O2) was studied. Highly reactive oxygen radicals, namely, superoxide anion (O2•-) and hydroxyl radicals (•OH), were investigated by the use of electron paramagnetic resonance spectroscopy. All species amounts were detected for three different treatment cases: Plasma jet generated VUV and UV radiation, plasma jet generated UV radiation without VUV part, and complete plasma jet including all reactive components additionally to VUV and UV radiation. It was found that a considerable amount of radicals are generated by the plasma generated photoemission. From the experiments, estimation on the low hazard potential of plasma generated VUV radiation is discussed.

  11. Impact of plasma jet vacuum ultraviolet radiation on reactive oxygen species generation in bio-relevant liquids

    SciTech Connect

    Jablonowski, H.; Hammer, M. U.; Reuter, S.; Bussiahn, R.; Weltmann, K.-D.; Woedtke, Th. von

    2015-12-15

    Plasma medicine utilizes the combined interaction of plasma produced reactive components. These are reactive atoms, molecules, ions, metastable species, and radiation. Here, ultraviolet (UV, 100–400 nm) and, in particular, vacuum ultraviolet (VUV, 10–200 nm) radiation generated by an atmospheric pressure argon plasma jet were investigated regarding plasma emission, absorption in a humidified atmosphere and in solutions relevant for plasma medicine. The energy absorption was obtained for simple solutions like distilled water (dH{sub 2}O) or ultrapure water and sodium chloride (NaCl) solution as well as for more complex ones, for example, Rosewell Park Memorial Institute (RPMI 1640) cell culture media. As moderate stable reactive oxygen species, hydrogen peroxide (H{sub 2}O{sub 2}) was studied. Highly reactive oxygen radicals, namely, superoxide anion (O{sub 2}{sup •−}) and hydroxyl radicals ({sup •}OH), were investigated by the use of electron paramagnetic resonance spectroscopy. All species amounts were detected for three different treatment cases: Plasma jet generated VUV and UV radiation, plasma jet generated UV radiation without VUV part, and complete plasma jet including all reactive components additionally to VUV and UV radiation. It was found that a considerable amount of radicals are generated by the plasma generated photoemission. From the experiments, estimation on the low hazard potential of plasma generated VUV radiation is discussed.

  12. Corrosion-induced gas generation in a nuclear waste repository: Reactive geochemistry and multiphase flow effect

    SciTech Connect

    Xu, T.; Senger, R.; Finsterle, S.

    2008-10-15

    Corrosion of steel canisters, stored in a repository for spent fuel and high-level nuclear wastes, leads to the generation and accumulation of hydrogen gas in the backfilled emplacement tunnels, which may significantly affect long-term repository safety. Previous studies used H{sub 2} generation rates based on the volume of the waste or canister material and the stoichiometry of the corrosion reaction. However, iron corrosion and H{sub 2} generation rates vary with time, depending on factors such as amount of iron, water availability, water contact area, and aqueous and solid chemistry. To account for these factors and feedback mechanisms, we developed a chemistry model related to iron corrosion, coupled with two-phase (liquid and gas) flow phenomena that are driven by gas-pressure buildup associated with H{sub 2} generation and water consumption. Results indicate that by dynamically calculating H{sub 2} generation rates based on a simple model of corrosion chemistry, and by coupling this corrosion reaction with two-phase flow processes, the degree and extent of gas pressure buildup could be much smaller compared to a model that neglects the coupling between flow and reactive transport mechanisms. By considering the feedback of corrosion chemistry, the gas pressure increases initially at the canister, but later decreases and eventually returns to a stabilized pressure that is slightly higher than the background pressure. The current study focuses on corrosion under anaerobic conditions for which the coupled hydrogeochemical model was used to examine the role of selected physical parameters on the H{sub 2} gas generation and corresponding pressure buildup in a nuclear waste repository. The developed model can be applied to evaluate the effect of water and mineral chemistry of the buffer and host rock on the corrosion reaction for future site-specific studies.

  13. Measurements of UV-generated free radicals/reactive oxygen species (ROS) in skin

    NASA Astrophysics Data System (ADS)

    Herrling, Th.; Jung, K.; Fuchs, J.

    2006-03-01

    Free radicals/reactive oxygen species (ROS) generated in skin by UV irradiation were measured by electron spin resonance (ESR). To increase the sensitivity of measurement the short life free radicals/ROS were scavenged and accumulated by using the nitroxyl probe 3-carboxy-2,2,5,5-tetrametylpyrrolidine-1-oxyl (PCA). The spatial distribution of free radicals/ROS measured in pig skin biopsies with ESR imaging after UV irradiation corresponds to the intensity decay of irradiance in the depth of the skin. The main part of free radicals/ROS were generated by UVA (320-400 nm) so that the spatial distribution of free radicals reaches up to the lower side of the dermis. In vivo measurements on human skin were performed with a L-band ESR spectrometer and a surface coil integrating the signal intensities from all skin layers to get a sufficient signal amplitude. Using this experimental arrangement the protection of UVB and UVA/B filter against the generation of free radicals/ROS in skin were measured. The protection against ROS and the repair of damages caused by them can be realized with active antioxidants characterized by a high antioxidative power (AP). The effect of UV filter and antioxidants corresponding to their protection against free radicals/ROS in skin generated by UVAB irradiation can be quantified by the new radical sun protection factor (RSF). The RSF indicates the increase of time for staying in the sun to generate the same number of free radicals/ROS in the skin like for the unprotected skin. Regarding the amount of generated free radicals/ROS in skin as an biophysical endpoint the RSF characterizes both the protection against UVB and UVA radiation.

  14. Generation of Reactive Oxygen and Anti-Oxidant Species by Hydrodynamically-Stressed Suspensions of Morinda citrofolia

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The generation of reactive oxygen species (ROS) by plant cell suspension cultures, in response to the imposition of both biotic and abiotic stress, is well-documented. This study investigated the generation of hydrogen peroxide by hydrodynamically-stressed cultures of Morinda citrifolia, over a 5-ho...

  15. Internally Generated Reactivation of Single Neurons in Human Hippocampus During Free Recall

    PubMed Central

    Gelbard-Sagiv, Hagar; Mukamel, Roy; Harel, Michal; Malach, Rafael; Fried, Itzhak

    2009-01-01

    The emergence of memory, a trace of things past, into human consciousness is one of the greatest mysteries of the human mind. Whereas the neuronal basis of recognition memory can be probed experimentally in human and nonhuman primates, the study of free recall requires that the mind declare the occurrence of a recalled memory (an event intrinsic to the organism and invisible to an observer). Here, we report the activity of single neurons in the human hippocampus and surrounding areas when subjects first view cinematic episodes consisting of audiovisual sequences and again later when they freely recall these episodes. A subset of these neurons exhibited selective firing, which often persisted throughout and following specific episodes for as long as 12 seconds. Verbal reports of memories of these specific episodes at the time of free recall were preceded by selective reactivation of the same hippocampal and entorhinal cortex neurons. We suggest that this reactivation is an internally generated neuronal correlate for the subjective experience of spontaneous emergence of human recollection. PMID:18772395

  16. Manipulating the selection forces during affinity maturation to generate cross-reactive HIV antibodies

    PubMed Central

    Wang, Shenshen; Mata-Fink, Jordi; Kriegsman, Barry; Hanson, Melissa; Irvine, Darrell J.; Eisen, Herman N.; Burton, Dennis R.; Wittrup, K. Dane; Kardar, Mehran; Chakraborty, Arup K.

    2015-01-01

    Summary Generation of potent antibodies by a mutation-selection process called affinity maturation is a key component of effective immune responses. Antibodies that protect against highly mutable pathogens must neutralize diverse strains. Developing effective immunization strategies to drive their evolution requires understanding how affinity maturation happens in an enviroment where variants of the same antigen are present. We present an in silico model of affinity maturation driven by antigen variants which reveals that induction of cross-reactive antibodies often occurs with low probability because conflicting selection forces, imposed by different antigen variants, can frustrate affinity maturation. We describe how variables such as temporal pattern of antigen administration influence the outcome of this frustrated evolutionary process. Our calculations predict, and experiments in mice with variant gp120 constructs of the HIV envelope protein confirm, that sequential immunization with antigen variants is preferred over a cocktail for induction of cross-reactive antibodies focused on the shared CD4 binding site epitope. PMID:25662010

  17. Cytotoxicity of InP/ZnS quantum dots related to reactive oxygen species generation.

    SciTech Connect

    Chibli, H.; Carlini, L.; Park, S.; Dimitrijevic, N. M.; Nadeau, J. L.

    2011-01-01

    Indium phosphide (InP) quantum dots (QDs) have emerged as a presumably less hazardous alternative to cadmium-based particles, but their cytotoxicity has not been well examined. Although their constituent elements are of very low toxicity to cells in culture, they nonetheless exhibit phototoxicity related to generation of reactive oxygen species by excited electrons and/or holes interacting with water and molecular oxygen. Using spin-trap electron paramagnetic resonance (EPR) spectroscopy and reporter assays, we find a considerable amount of superoxide and a small amount of hydroxyl radical formed under visible illumination of biocompatible InP QDs with a single ZnS shell, comparable to what is seen with CdTe. A double thickness shell reduces the reactive oxygen species concentration approximately two-fold. Survival assays in five cell lines correspondingly indicate a distinct reduction in toxicity with the double-shell InP QDs. Toxicity varies significantly across cell lines according to the efficiency of uptake, being overall significantly less than what is seen with CdTe or CdSe/ZnS. This indicates that InP QDs are a useful alternative to cadmium-containing QDs, while remaining capable of electron-transfer processes that may be undesirable or which may be exploited for photosensitization applications.

  18. Fucoidan protects ARPE-19 cells from oxidative stress via normalization of reactive oxygen species generation through the Ca²⁺-dependent ERK signaling pathway.

    PubMed

    Li, Xiaoxia; Zhao, Haiyan; Wang, Qingfa; Liang, Hongyan; Jiang, Xiaofeng

    2015-05-01

    Diabetic retinopathy (DR) is a common complication of diabetes mellitus (DM) and it is the main cause of loss of vision. In previous years, interest in the biological activities of marine organisms has intensified. The effect of fucoidan from the seaweed Fucus vesiculosus on the molecular mechanisms of numerous diseases has been studied, while to date, its effect on DR was yet to be investigated. Therefore, the aim of the present study was to evaluate the role of fucoidan in DR. The human retinal pigment epithelial cell line ARPE‑19 was exposed to high D‑glucose in the presence or absence of fucoidan. Cell viability was monitored using MTT and lactate dehydrogenase assays. The intracellular reactive oxygen species (ROS) generation was measured using fluorescence spectrophotometry. Cell apoptosis was measured by flow cytometry using Annexin V‑fluorescein isothiocyanate staining. Ca2+ influx was measured with a calcium imaging system and the activation of the extracellular signal‑regulated kinase (ERK) protein was evaluated using western blot analysis. The non‑toxic fucoidan protected ARPE‑19 cells from high glucose‑induced cell death and normalized high glucose‑induced generation of ROS. Fucoidan also inhibited high glucose‑induced cell apoptosis, as well as the Ca2+ influx and ERK1/2 phosphorylation in ARPE‑19 cells. Taken together, these findings indicated that fucoidan protects ARPE‑19 cells against high glucose‑induced oxidative damage via normalization of ROS generation through the Ca2+‑dependent ERK signaling pathway. PMID:25606812

  19. Wear Particles Impair Antimicrobial Activity Via Suppression of Reactive Oxygen Species Generation and ERK1/2 Phosphorylation in Activated Macrophages.

    PubMed

    Chen, Weishen; Li, Ziqing; Guo, Ying; Zhou, Yuhuan; Zhang, Yangchun; Luo, Guotian; Yang, Xing; Li, Chaohong; Liao, Weiming; Sheng, Puyi

    2015-01-01

    Implant-related infection (IRI) is closely related to the local immunity of peri-implant tissues. The generation of reactive oxygen species (ROS) in activated macrophages plays a prominent role in the innate immune response. In previous studies, we indicated that implant wear particles promote endotoxin tolerance by decreasing the release of proinflammatory cytokines. However, it is unclear whether ROS are involved in the damage of the local immunity of peri-implant tissues. In the present study, we assessed the mechanism of local immunosuppression using titanium (Ti) particles and/or lipopolysaccharide (LPS) to stimulate RAW 264.7 cells. The results indicate that the Ti particles induced the generation of a moderate amount of ROS through nicotinamide adenine dinucleotide phosphate oxidase-1, but not through catalase. Pre-exposure to Ti particles inhibited ROS generation and extracellular-regulated protein kinase activation in LPS-stimulated macrophages. These findings indicate that chronic stimulation by Ti particles may lead to a state of oxidative stress and persistent inflammation, which may result in the attenuation of the immune response of macrophages to bacterial components such as LPS. Eventually, immunosuppression develops in peri-implant tissues, which may be a risk factor for IRI. PMID:25577344

  20. Tks5-dependent, Nox-mediated Generation of Reactive Oxygen Species is Necessary for Invadopodia Formation*

    PubMed Central

    Diaz, Begoña; Shani, Gidon; Pass, Ian; Anderson, Diana; Quintavalle, Manuela; Courtneidge, Sara A.

    2009-01-01

    Invadopodia are actin-rich membrane protrusions of cancer cells which facilitate pericellular proteolysis and invasive behavior. We show here that reactive oxygen species (ROS) generated by the NADPH oxidase (Nox) system are necessary for invadopodia formation and function. The invadopodia protein Tks5 is structurally related to p47phox, a Nox component in phagocytic cells. Knockdown of Tks5 reduces total ROS levels in cancer cells. Furthermore, Tks5 and p22phox can associate with each other, suggesting that Tks5 is part of the Nox complex. Tyrosine phosphorylation of Tks5 and Tks4, but not other Src substrates, is reduced by Nox inhibition. We propose that Tks5 facilitates the production of ROS necessary for invadopodia formation, and that in turn ROS modulates Tks5 tyrosine phosphorylation in a positive feedback loop. PMID:19755709

  1. Reactive oxygen species generated from skeletal muscles are required for gecko tail regeneration.

    PubMed

    Zhang, Qing; Wang, Yingjie; Man, Lili; Zhu, Ziwen; Bai, Xue; Wei, Sumei; Liu, Yan; Liu, Mei; Wang, Xiaochuan; Gu, Xiaosong; Wang, Yongjun

    2016-01-01

    Reactive oxygen species (ROS) participate in various physiological and pathological functions following generation from different types of cells. Here we explore ROS functions on spontaneous tail regeneration using gecko model. ROS were mainly produced in the skeletal muscle after tail amputation, showing a temporal increase as the regeneration proceeded. Inhibition of the ROS production influenced the formation of autophagy in the skeletal muscles, and as a consequence, the length of the regenerating tail. Transcriptome analysis has shown that NADPH oxidase (NOX2) and the subunits (p40(phox) and p47(phox)) are involved in the ROS production. ROS promoted the formation of autophagy through regulation of both ULK and MAPK activities. Our results suggest that ROS produced by skeletal muscles are required for the successful gecko tail regeneration. PMID:26853930

  2. Hemoglobin fructation promotes heme degradation through the generation of endogenous reactive oxygen species

    NASA Astrophysics Data System (ADS)

    Goodarzi, M.; Moosavi-Movahedi, A. A.; Habibi-Rezaei, M.; Shourian, M.; Ghourchian, H.; Ahmad, F.; Farhadi, M.; Saboury, A. A.; Sheibani, N.

    2014-09-01

    Protein glycation is a cascade of nonenzymatic reactions between reducing sugars and amino groups of proteins. It is referred to as fructation when the reducing monosaccharide is fructose. Some potential mechanisms have been suggested for the generation of reactive oxygen species (ROS) by protein glycation reactions in the presence of glucose. In this state, glucose autoxidation, ketoamine, and oxidative advance glycation end products (AGEs) formation are considered as major sources of ROS and perhaps heme degradation during hemoglobin glycation. However, whether fructose mediated glycation produces ROS and heme degradation is unknown. Here we report that ROS (H2O2) production occurred during hemoglobin fructation in vitro using chemiluminescence methods. The enhanced heme exposure and degradation were determined using UV-Vis and fluorescence spectrophotometry. Following accumulation of ROS, heme degradation products were accumulated reaching a plateau along with the detected ROS. Thus, fructose may make a significant contribution to the production of ROS, glycation of proteins, and heme degradation during diabetes.

  3. Reactive oxygen species generated from skeletal muscles are required for gecko tail regeneration

    PubMed Central

    Zhang, Qing; Wang, Yingjie; Man, Lili; Zhu, Ziwen; Bai, Xue; Wei, Sumei; Liu, Yan; Liu, Mei; Wang, Xiaochuan; Gu, Xiaosong; Wang, Yongjun

    2016-01-01

    Reactive oxygen species (ROS) participate in various physiological and pathological functions following generation from different types of cells. Here we explore ROS functions on spontaneous tail regeneration using gecko model. ROS were mainly produced in the skeletal muscle after tail amputation, showing a temporal increase as the regeneration proceeded. Inhibition of the ROS production influenced the formation of autophagy in the skeletal muscles, and as a consequence, the length of the regenerating tail. Transcriptome analysis has shown that NADPH oxidase (NOX2) and the subunits (p40phox and p47phox) are involved in the ROS production. ROS promoted the formation of autophagy through regulation of both ULK and MAPK activities. Our results suggest that ROS produced by skeletal muscles are required for the successful gecko tail regeneration. PMID:26853930

  4. p53 activation contributes to patulin-induced nephrotoxicity via modulation of reactive oxygen species generation

    PubMed Central

    Jin, Huan; Yin, Shutao; Song, Xinhua; Zhang, Enxiang; Fan, Lihong; Hu, Hongbo

    2016-01-01

    Patulin is a major mycotoxin found in fungal contaminated fruits and their derivative products. Previous studies showed that patulin was able to induce increase of reactive oxygen species (ROS) generation and oxidative stress was suggested to play a pivotal role in patulin-induced multiple toxic signaling. The objective of the present study was to investigate the functional role of p53 in patulin-induced oxidative stress. Our study demonstrated that higher levels of ROS generation and DNA damage were induced in wild-type p53 cell lines than that found in either knockdown or knockout p53 cell lines in response to patulin exposure, suggesting p53 activation contributed to patulin-induced ROS generation. Mechanistically, we revealed that the pro-oxidant role of p53 in response to patulin was attributed to its ability to suppress catalase activity through up-regulation of PIG3. Moreover, these in vitro findings were further validated in the p53 wild-type/knockout mouse model. To the best of our knowledge, this is the first report addressing the functional role of p53 in patulin-induced oxidative stress. The findings of the present study provided novel insights into understanding mechanisms behind oxidative stress in response to patulin exposure. PMID:27071452

  5. Estimation of reactive power export and import capability for non-utility generators

    SciTech Connect

    Nolan, G.J.; Winge, D.E.; Khalafalla, E.B.; Swartley, B.S.; Arnold, E.H.

    1995-12-31

    Non-utility generators (NUGs) are typically required by their electric power sales agreement to have the capability to supply power to the purchasing utility near unity power factor. With the advent of large combustion turbine generators, many NUGs are simple or combined cycle facilities with generating capacities in excess of low megawatts. Utilities are recognizing that these large NUG facilities can be significant contributors to the reactive power (megavars-Mvars) flow needed to support system requirements and transmission level grid voltages. NUGs are now being dispatched for Mvar export and import activities to meet utility requirements. The ability of a NUG to export or import Mvars is highly dependent on the actual transmission intertie voltage level. Unless plant specific studies are performed, this can be difficult to ascertain for the NUG`s operating and engineering personnel. This paper presents a method, based on system load flow studies, for estimating the capacity of a NUG to export or import Mvars at a given transmission intertie voltage level. It also explores other key variables which determine the ability of a NUG to export or import VARS. This methodology can be used to aid operating personnel at existing facilities or as a guide during the design of a new facility.

  6. Urea degradation by electrochemically generated reactive chlorine species: products and reaction pathways.

    PubMed

    Cho, Kangwoo; Hoffmann, Michael R

    2014-10-01

    This study investigated the transformation of urea by electrochemically generated reactive chlorine species (RCS). Solutions of urea with chloride ions were electrolyzed using a bismuth doped TiO2 (BiOx/TiO2) anode coupled with a stainless steel cathode at applied anodic potentials (Ea) of either +2.2 V or +3.0 V versus the normal hydrogen electrode. In NaCl solution, the current efficiency of RCS generation was near 30% at both potentials. In divided cell experiments, the pseudo-first-order rate of total nitrogen decay was an order of magnitude higher at Ea of +3.0 V than at +2.2 V, presumably because dichlorine radical (Cl2(-)·) ions facilitate the urea transformation primary driven by free chlorine. Quadrupole mass spectrometer analysis of the reactor headspace revealed that N2 and CO2 are the primary gaseous products of the oxidation of urea, whose urea-N was completely transformed into N2 (91%) and NO3(-) (9%). The higher reaction selectivity with respect to N2 production can be ascribed to a low operational ratio of free available chlorine to N. The mass-balance analysis recovered urea-C as CO2 at 77%, while CO generation most likely accounts for the residual carbon. In light of these results, we propose a reaction mechanism involving chloramines and chloramides as reaction intermediates, where the initial chlorination is the rate-determining step in the overall sequence of reactions. PMID:25219459

  7. Surface functionalization of titanium dioxide nanoparticles: Photo-stability and reactive oxygen species (ROS) generation

    NASA Astrophysics Data System (ADS)

    Louis, Kacie M.

    Metal oxide nanoparticles are becoming increasingly prevalent in society for applications of sunscreens, cosmetics, paints, biomedical imaging, and photovoltaics. Due to the increased surface area to volume ratio of nanoparticles compared to bulk materials, it is important to know the health and safety impacts of these materials. One mechanism of toxicity of nominally "safe" materials such as TiO 2 is through the photocatalytic generation of reactive oxygen species (ROS). ROS production and ligand degradation can affect the bioavailability of these particles in aqueous organisms. We have investigated ROS generation by functionalized TiO2 nanoparticles and its influence on aggregation and bioavailability and toxicity to zebrafish embryos/larvae. For these studies we investigated anatase TiO2 nanoparticles. For application purposes and solution stability, the TiO2 nanoparticles were functionalized with a variety of ligands such as citrate, 3,4-dihydroxybenzaldehyde, and ascorbate. We quantitatively examined the amount of ROS produced in aqueous solution using fluorescent probes and see that more ROS is produced under UV light than in the dark control. Our measurements show that TiO2 toxicity reaches a maximum for nanoparticles with smaller diameters, and is correlated with surface area dependent changes in ROS generation. In an effort to reduce toxicity through control of the surface and surface ligands, we synthesized anatase nanoparticles of different sizes, functionalized them with different ligands, and examined the resulting ROS generation and ligand stability. Using a modular ligand containing a hydrophobic inner region and a hydrophilic outer region, we synthesized water-stable nanoparticles, via two different chemical reactions, having much-reduced ROS generation and thus reduced toxicity. These results suggest new strategies for making safer nanoparticles while still retaining their desired properties. We also examine the degradation of the different ligands

  8. Reactive Oxygen Species Generation Linked to Sources of Atmospheric Particulate Matter and Cardiorespiratory Effects.

    PubMed

    Bates, Josephine T; Weber, Rodney J; Abrams, Joseph; Verma, Vishal; Fang, Ting; Klein, Mitchel; Strickland, Matthew J; Sarnat, Stefanie Ebelt; Chang, Howard H; Mulholland, James A; Tolbert, Paige E; Russell, Armistead G

    2015-11-17

    Exposure to atmospheric fine particulate matter (PM2.5) is associated with cardiorespiratory morbidity and mortality, but the mechanisms are not well understood. We assess the hypothesis that PM2.5 induces oxidative stress in the body via catalytic generation of reactive oxygen species (ROS). A dithiothreitol (DTT) assay was used to measure the ROS-generation potential of water-soluble PM2.5. Source apportionment on ambient (Atlanta, GA) PM2.5 was performed using the chemical mass balance method with ensemble-averaged source impact profiles. Linear regression analysis was used to relate PM2.5 emission sources to ROS-generation potential and to estimate historical levels of DTT activity for use in an epidemiologic analysis for the period of 1998-2009. Light-duty gasoline vehicles (LDGV) exhibited the highest intrinsic DTT activity, followed by biomass burning (BURN) and heavy-duty diesel vehicles (HDDV) (0.11 ± 0.02, 0.069 ± 0.02, and 0.052 ± 0.01 nmol min(-1) μg(-1)source, respectively). BURN contributed the largest fraction to total DTT activity over the study period, followed by LDGV and HDDV (45, 20, and 14%, respectively). DTT activity was more strongly associated with emergency department visits for asthma/wheezing and congestive heart failure than PM2.5. This work provides further epidemiologic evidence of a biologically plausible mechanism, that of oxidative stress, for associations of adverse health outcomes with PM2.5 mass and supports continued assessment of the utility of the DTT activity assay as a measure of ROS-generating potential of particles. PMID:26457347

  9. REACTIVE OXYGEN SPECIES GENERATION BY THE ETHYLENE-BIS-DITHIOCARBAMATE (EBDC) FUNGICIDE MANCOZEB AND ITS CONTRIBUTION TO NEURONAL TOXICITY IN MESENCEPHALIC CELLS

    PubMed Central

    Domico, Lisa M.; Cooper, Keith R.; Bernard, Laura P.; Zeevalk, Gail D.

    2007-01-01

    Previous in vitro studies in our laboratory have shown that mancozeb (MZ) and maneb (MB), both widely used EBDC fungicides, are equipotent neurotoxicants that produce cell loss in mesencephalic dopaminergic and GABAergic cells after an acute 24 h exposure. Mitochondrial uncoupling and inhibition were associated with fungicide exposure. Inhibition of mitochondrial respiration is known to increase free radical production. Here the mechanism(s) of neuronal damage associated with MZ exposure was further explored by determining the role that reactive oxygen species (ROS) played in toxicity. Damage to mesencephalic dopamine and GABA cell populations were significantly attenuated when carried out in the presence of ascorbate or SOD indicative of a free radical mediated contribution to toxicity. ROS generation monitored by H2O2 production using Amplex Red increased in a dose-dependent manner in response to MZ. Inhibition of intracellular catalase with aminotriazole had little effect on H2O2 generation, whereas exogenously added catalase significantly reduced H2O2 production demonstrating a large extracellular contribution to ROS generation. Conversely, cells preloaded with the ROS indicator dye DCF showed significant MZ-induced ROS production, demonstrating an increase in intracellular ROS. Both the organic backbone of MZ as well as its associated Mn ion, but not Zn ion were responsible and required for H2O2 generation. The functionally diverse NADPH oxidase inhibitors, diphenylene iodonium chloride, apocynin, and 4-(2-aminoethyl)benzene- sulfonyl fluoride hydrochloride significantly attenuated H2O2 production by MZ. In growth medium lacking cells, MZ produced little H2O2, but enhanced H2O2 generation when added with xanthine plus xanthine oxidase whereas, in cultured cells, allopurinol partially attenuated H2O2 production by MZ. Minocycline, an inhibitor of microglial activation, modestly reduced H2O2 formation in mesencephalic cells. In contrast, neuronal enriched

  10. Cytotoxicity and reactive oxygen species generation from aggregated carbon and carbonaceous nanoparticulate materials

    PubMed Central

    Garza, Kristine M; Soto, Karla F; Murr, Lawrence E

    2008-01-01

    We have investigated the cytotoxicity and reactive oxygen species (ROS) generation for indoor and outdoor soots: candle, wood, diesel, tire, and natural gas burner soots – along with surrogate black carbon, various multiwall carbon nanotube aggregate materials, TiO2 (anatase) and chrysotile asbestos as reference materials. All soots were observed utilizing TEM and FESEM to be composed of aggregated, primary spherules (20–80 nm diameter) forming complex, branched fractal structures. These spherules were composed of intercalated, turbostratic arrangements of curved graphene fragments with varying concentrations of polycyclic aromatic hydrocarbon (PAH) isomers. In vitro cultures with an immortalized human lung epithelial carcinoma cell line (A549) treated with these materials showed decreased cell viability and variations in ROS production, with no correlations to PAH content. The data demonstrate that soots are cytotoxic and that cytotoxicity is not related to PAH content but is related to ROS generation, suggesting that soot induces cellular oxidative stress and that cell viability assays can be indicators of ROS production. PMID:18488419

  11. Generation of Reactive Oxygen Species via NOXa Is Important for Development and Pathogenicity of Mycosphaerella graminicola

    PubMed Central

    Choi, Yoon-E; Lee, Changsu

    2016-01-01

    The ascomycete fungus Mycosphaerella graminicola (synonym Zymoseptoria tritici) is an important pathogen of wheat causing economically significant losses. The primary nutritional mode of this fungus is thought to be hemibiotrophic. This pathogenic lifestyle is associated with an early biotrophic stage of nutrient uptake followed by a necrotrophic stage aided possibly by production of a toxin or reactive oxygen species (ROS). In many other fungi, the genes CREA and AREA are important during the biotrophic stage of infection, while the NOXa gene product is important during necrotrophic growth. To test the hypothesis that these genes are important for pathogenicity of M. graminicola, we employed an over-expression strategy for the selected target genes CREA, AREA, and NOXa, which might function as regulators of nutrient acquisition or ROS generation. Increased expressions of CREA, AREA, and NOXa in M. graminicola were confirmed via quantitative real-time PCR and strains were subsequently assayed for pathogenicity. Among them, the NOXa over-expression strain, NO2, resulted in significantly increased virulence. Moreover, instead of the usual filamentous growth, we observed a predominance of yeast-like growth of NO2 which was correlated with ROS production. Our data indicate that ROS generation via NOXa is important to pathogenicity as well as development in M. graminicola. PMID:27103853

  12. Cytotoxicity and reactive oxygen species generation from aggregated carbon and carbonaceous nanoparticulate materials.

    PubMed

    Garza, Kristine M; Soto, Karla F; Murr, Lawrence E

    2008-01-01

    We have investigated the cytotoxicity and reactive oxygen species (ROS) generation for indoor and outdoor soots: candle, wood, diesel, tire, and natural gas burner soots--along with surrogate black carbon, various multiwall carbon nanotube aggregate materials, TiO2 (anatase) and chrysotile asbestos as reference materials. All soots were observed utilizing TEM and FESEM to be composed of aggregated, primary spherules (20-80 nm diameter) forming complex, branched fractal structures. These spherules were composed of intercalated, turbostratic arrangements of curved graphene fragments with varying concentrations ofpolycyclic aromatic hydrocarbon (PAH) isomers. In vitro cultures with an immortalized human lung epithelial carcinoma cell line (A549) treated with these materials showed decreased cell viability and variations in ROS production, with no correlations to PAH content. The data demonstrate that soots are cytotoxic and that cytotoxicity is not related to PAH content but is related to ROS generation, suggesting that soot induces cellular oxidative stress and that cell viability assays can be indicators of ROS production. PMID:18488419

  13. Generation of Reactive Oxygen Species via NOXa Is Important for Development and Pathogenicity of Mycosphaerella graminicola.

    PubMed

    Choi, Yoon-E; Lee, Changsu; Goodwin, Stephen B

    2016-03-01

    The ascomycete fungus Mycosphaerella graminicola (synonym Zymoseptoria tritici) is an important pathogen of wheat causing economically significant losses. The primary nutritional mode of this fungus is thought to be hemibiotrophic. This pathogenic lifestyle is associated with an early biotrophic stage of nutrient uptake followed by a necrotrophic stage aided possibly by production of a toxin or reactive oxygen species (ROS). In many other fungi, the genes CREA and AREA are important during the biotrophic stage of infection, while the NOXa gene product is important during necrotrophic growth. To test the hypothesis that these genes are important for pathogenicity of M. graminicola, we employed an over-expression strategy for the selected target genes CREA, AREA, and NOXa, which might function as regulators of nutrient acquisition or ROS generation. Increased expressions of CREA, AREA, and NOXa in M. graminicola were confirmed via quantitative real-time PCR and strains were subsequently assayed for pathogenicity. Among them, the NOXa over-expression strain, NO2, resulted in significantly increased virulence. Moreover, instead of the usual filamentous growth, we observed a predominance of yeast-like growth of NO2 which was correlated with ROS production. Our data indicate that ROS generation via NOXa is important to pathogenicity as well as development in M. graminicola. PMID:27103853

  14. Rapid hydrogen gas generation using reactive thermal decomposition of uranium hydride.

    SciTech Connect

    Kanouff, Michael P.; Van Blarigan, Peter; Robinson, David B.; Shugard, Andrew D.; Gharagozloo, Patricia E.; Buffleben, George M.; James, Scott Carlton; Mills, Bernice E.

    2011-09-01

    Oxygen gas injection has been studied as one method for rapidly generating hydrogen gas from a uranium hydride storage system. Small scale reactors, 2.9 g UH{sub 3}, were used to study the process experimentally. Complimentary numerical simulations were used to better characterize and understand the strongly coupled chemical and thermal transport processes controlling hydrogen gas liberation. The results indicate that UH{sub 3} and O{sub 2} are sufficiently reactive to enable a well designed system to release gram quantities of hydrogen in {approx} 2 seconds over a broad temperature range. The major system-design challenge appears to be heat management. In addition to the oxidation tests, H/D isotope exchange experiments were performed. The rate limiting step in the overall gas-to-particle exchange process was found to be hydrogen diffusion in the {approx}0.5 {mu}m hydride particles. The experiments generated a set of high quality experimental data; from which effective intra-particle diffusion coefficients can be inferred.

  15. PKCα promotes generation of reactive oxygen species via DUOX2 in hepatocellular carcinoma

    SciTech Connect

    Wang, Jiajun; Shao, Miaomiao; Liu, Min; Peng, Peike; Li, Lili; Wu, Weicheng; Wang, Lan; Duan, Fangfang; Zhang, Mingming; Song, Shushu; Jia, Dongwei; Ruan, Yuanyuan; Gu, Jianxin

    2015-08-07

    Hepatocellular carcinoma (HCC) remains the second leading cause of cancer-related death worldwide, and elevated rates of reactive oxygen species (ROS) have long been considered as a hallmark of almost all types of cancer including HCC. Protein kinase C alpha (PKCα), a serine/threonine kinase among conventional PKC family, is recognized as a major player in signal transduction and tumor progression. Overexpression of PKCα is commonly observed in human HCC and associated with its poor prognosis. However, how PKCα is involved in hepatocellular carcinogenesis remains not fully understood. In this study, we found that among the members of conventional PKC family, PKCα, but not PKCβI or βII, promoted ROS production in HCC cells. PKCα stimulated generation of ROS by up-regulating DUOX2 at post-transcriptional level. Depletion of DUOX2 abrogated PKCα-induced activation of AKT/MAPK pathways as well as cell proliferation, migration and invasion in HCC cells. Moreover, the expression of DUOX2 and PKCα was well positively correlated in both HCC cell lines and patient samples. Collectively, our findings demonstrate that PKCα plays a critical role in HCC development by inducing DUOX2 expression and ROS generation, and propose a strategy to target PKCα/DUOX2 as a potential adjuvant therapy for HCC treatment. - Highlights: • PKCα promotes the generation of ROS in hepatocellular carcinoma. • PKCα induces ROS production by up-regulating DUOX2 at post-transcriptional level. • DUOX2 is required for PKCα-induced AKT/MAPK activation and tumor progression in HCC. • The expression of PKCα is positively correlated with DUOX2 in HCC.

  16. TGF-β1 stimulates mitochondrial oxidative phosphorylation and generation of reactive oxygen species in cultured mouse podocytes, mediated in part by the mTOR pathway

    PubMed Central

    Abe, Yoshifusa; Sakairi, Toru; Beeson, Craig

    2013-01-01

    Transforming growth factor (TGF)-β has been associated with podocyte injury; we have examined its effect on podocyte bioenergetics. We studied transformed mouse podocytes, exposed to TGF-β1, using a label-free assay system, Seahorse XF24, which measures oxygen consumption rates (OCR) and extracellular acidification rates (ECAR). Both basal OCR and ATP generation-coupled OCR were significantly higher in podocytes exposed to 0.3–10 ng/ml of TGF-β1 for 24, 48, and 72 h. TGF-β1 (3 ng/ml) increased oxidative capacity 75%, and 96% relative to control after 48 and 72 h, respectively. ATP content was increased 19% and 30% relative to control after a 48- and 72-h exposure, respectively. Under conditions of maximal mitochondrial function, TGF-β1 increased palmitate-driven OCR by 49%. Thus, TGF-β1 increases mitochondrial oxygen consumption and ATP generation in the presence of diverse energy substrates. TGF-β1 did not increase cell number or mitochondrial DNA copy number but did increase mitochondrial membrane potential (MMP), which could explain the OCR increase. Reactive oxygen species (ROS) increased by 32% after TGF-β1 exposure for 48 h. TGF-β activated the mammalian target of rapamycin (mTOR) pathway, and rapamycin reduced the TGF-β1-stimulated increases in OCR, ECAR, ATP generation, cellular metabolic activity, and protein generation. Our data suggest that TGF-β1, acting, in part, via mTOR, increases mitochondrial MMP and OCR, resulting in increased ROS generation and that this may contribute to podocyte injury. PMID:24049142

  17. Inhibitory effects of hypo-osmotic stress on extracellular carbonic anhydrase and photosynthetic efficiency of green alga Dunaliella salina possibly through reactive oxygen species formation.

    PubMed

    Liu, Wenhua; Ming, Yao; Li, Ping; Huang, Zhongwen

    2012-05-01

    In this study, Dunaliella salina (D. salina) maintained in 30‰ salinity for more than two years was exposed to the salinities of 5‰, 10‰, 20‰, 30‰ (control) in order to investigate oxidative burst and it's possible connection with extracellular carbonic anhydrase (CA) under hypo-osmotic stress (low salinity). The results indicated that intracellular ROS contents increased significantly when cells were exposed to salinity of 5 and 10‰, and the increase also occurred at 20‰ salinity. The activity of extracellular CA and its gene (P60) expression decreased significantly when cells were exposed to salinity of 5-20‰. Data from H₂O₂ treatments hinted that ROS production was possibly one of the factors affecting CA, including enzyme activity and gene expression levels. Significant inhibition of effective quantum efficiency of PSII and photosynthetic oxygen evolution rate were observed with the increase of ROS production and decline of CA activities. Taken together, hypo-osmotic stresses could induce ROS production in D. salina, and CA enzyme activities and expression levels were consequently inhibited. As a result, algal photosynthesis and oxygen evolution were inhibited. PMID:22377429

  18. Effect of reactive oxygen species (ROS) generating system for control of airborne microorganisms in meat processing environment

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The effectiveness of reactive oxygen species (ROS) generating AirOcare equipment on the reduction of airborne bacteria in a meat processing environment was determined. Serratia marcescens and lactic acid bacteria (Lactococcus lactis subsp. lactis and Lactobacillus plantarum) were used to artificiall...

  19. Efficient generation of cavitation bubbles and reactive oxygen species using triggered high-intensity focused ultrasound sequence for sonodynamic treatment

    NASA Astrophysics Data System (ADS)

    Yasuda, Jun; Yoshizawa, Shin; Umemura, Shin-ichiro

    2016-07-01

    Sonodynamic treatment is a method of treating cancer using reactive oxygen species (ROS) generated by cavitation bubbles in collaboration with a sonosensitizer at a target tissue. In this treatment method, both localized ROS generation and ROS generation with high efficiency are important. In this study, a triggered high-intensity focused ultrasound (HIFU) sequence, which consists of a short, extremely high intensity pulse immediately followed by a long, moderate-intensity burst, was employed for the efficient generation of ROS. In experiments, a solution sealed in a chamber was exposed to a triggered HIFU sequence. Then, the distribution of generated ROS was observed by the luminol reaction, and the amount of generated ROS was quantified using KI method. As a result, the localized ROS generation was demonstrated by light emission from the luminol reaction. Moreover, it was demonstrated that the triggered HIFU sequence has higher efficiency of ROS generation by both the KI method and the luminol reaction emission.

  20. Generation of Functional Insulin-Producing Cells From Mouse Embryonic Stem Cells Through 804G Cell-Derived Extracellular Matrix and Protein Transduction of Transcription Factors

    PubMed Central

    Kaitsuka, Taku; Noguchi, Hirofumi; Shiraki, Nobuaki; Kubo, Takuya; Wei, Fan-Yan; Hakim, Farzana; Kume, Shoen

    2014-01-01

    Embryonic stem (ES) and induced pluripotent stem (iPS) cells have potential applications to regenerative medicine for diabetes; however, a useful and safe way to generate pancreatic β cells has not been developed. In this study, we tried to establish an effective method of differentiation through the protein transduction of three transcription factors (Pdx1, NeuroD, and MafA) important to pancreatic β cell development. The method poses no risk of unexpected genetic modifications in target cells. Transduction of the three proteins induced the differentiation of mouse ES and mouse iPS cells into insulin-producing cells. Furthermore, a laminin-5-rich extracellular matrix efficiently induced differentiation under feeder-free conditions. Cell differentiation was confirmed with the expression of the insulin 1 gene in addition to marker genes in pancreatic β cells, the differentiated cells secreted glucose-responsive C-peptide, and their transplantation restored normoglycemia in diabetic mice. Moreover, Pdx1 protein transduction had facilitative effects on differentiation into pancreatic endocrine progenitors from human iPS cells. These results suggest the direct delivery of recombinant proteins and treatment with laminin-5-rich extracellular matrix to be useful for the generation of insulin-producing cells. PMID:24292793

  1. Neutrophil Extracellular Traps Identification in Tegumentary Lesions of Patients with Paracoccidioidomycosis and Different Patterns of NETs Generation In Vitro.

    PubMed

    Della Coletta, Amanda Manoel; Bachiega, Tatiana Fernanda; de Quaglia e Silva, Juliana Carvalho; Soares, Ângela Maria Victoriano de Campos; De Faveri, Julio; Marques, Silvio Alencar; Marques, Mariângela Esther Alencar; Ximenes, Valdecir Farias; Dias-Melicio, Luciane Alarcão

    2015-01-01

    Paracoccidioidomycosis (PCM) is a systemic mycosis, endemic in most Latin American countries, especially in Brazil. It is caused by the thermo-dimorphic fungus of the genus Paracoccidioides (Paracoccidioides brasiliensis and Paracoccidioides lutzii). Innate immune response plays a crucial role in host defense against fungal infections, and neutrophils (PMNs) are able to combat microorganisms with three different mechanisms: phagocytosis, secretion of granular proteins, which have antimicrobial properties, and the most recent described mechanism called NETosis. This new process is characterized by the release of net-like structures called Neutrophil Extracellular Traps (NETs), which is composed of nuclear (decondensed DNA and histones) and granular material such as elastase. Several microorganisms have the ability of inducing NETs formation, including gram-positive and gram-negative bacteria, viruses and some fungi. We proposed to identify NETs in tegumentary lesions of patients with PCM and to analyze the interaction between two strains of P. brasiliensis and human PMNs by NETs formation in vitro. In this context, the presence of NETs in vivo was evidenced in tegumentary lesions of patients with PCM by confocal spectrum analyzer. Furthermore, we showed that the high virulent P. brasiliensis strain 18 (Pb18) and the lower virulent strain Pb265 are able to induce different patterns of NETs formation in vitro. The quantification of extracellular DNA corroborates the idea of the ability of P. brasiliensis in inducing NETs release. In conclusion, our data show for the first time the identification of NETs in lesions of patients with PCM and demonstrate distinct patterns of NETs in cultures challenged with fungi in vitro. The presence of NETs components both in vivo and in vitro open new possibilities for the detailed investigation of immunity in PCM. PMID:26327485

  2. Neutrophil Extracellular Traps Identification in Tegumentary Lesions of Patients with Paracoccidioidomycosis and Different Patterns of NETs Generation In Vitro

    PubMed Central

    Della Coletta, Amanda Manoel; Bachiega, Tatiana Fernanda; de Quaglia e Silva, Juliana Carvalho; Soares, Ângela Maria Victoriano de Campos; De Faveri, Julio; Marques, Silvio Alencar; Marques, Mariângela Esther Alencar; Ximenes, Valdecir Farias; Dias-Melicio, Luciane Alarcão

    2015-01-01

    Paracoccidioidomycosis (PCM) is a systemic mycosis, endemic in most Latin American countries, especially in Brazil. It is caused by the thermo-dimorphic fungus of the genus Paracoccidioides (Paracoccidioides brasiliensis and Paracoccidioides lutzii). Innate immune response plays a crucial role in host defense against fungal infections, and neutrophils (PMNs) are able to combat microorganisms with three different mechanisms: phagocytosis, secretion of granular proteins, which have antimicrobial properties, and the most recent described mechanism called NETosis. This new process is characterized by the release of net-like structures called Neutrophil Extracellular Traps (NETs), which is composed of nuclear (decondensed DNA and histones) and granular material such as elastase. Several microorganisms have the ability of inducing NETs formation, including gram-positive and gram-negative bacteria, viruses and some fungi. We proposed to identify NETs in tegumentary lesions of patients with PCM and to analyze the interaction between two strains of P. brasiliensis and human PMNs by NETs formation in vitro. In this context, the presence of NETs in vivo was evidenced in tegumentary lesions of patients with PCM by confocal spectrum analyzer. Furthermore, we showed that the high virulent P. brasiliensis strain 18 (Pb18) and the lower virulent strain Pb265 are able to induce different patterns of NETs formation in vitro. The quantification of extracellular DNA corroborates the idea of the ability of P. brasiliensis in inducing NETs release. In conclusion, our data show for the first time the identification of NETs in lesions of patients with PCM and demonstrate distinct patterns of NETs in cultures challenged with fungi in vitro. The presence of NETs components both in vivo and in vitro open new possibilities for the detailed investigation of immunity in PCM. PMID:26327485

  3. Controlled intracellular generation of reactive oxygen species in human mesenchymal stem cells using porphyrin conjugated nanoparticles

    NASA Astrophysics Data System (ADS)

    Lavado, Andrea S.; Chauhan, Veeren M.; Alhaj Zen, Amer; Giuntini, Francesca; Jones, D. Rhodri E.; Boyle, Ross W.; Beeby, Andrew; Chan, Weng C.; Aylott, Jonathan W.

    2015-08-01

    Nanoparticles capable of generating controlled amounts of intracellular reactive oxygen species (ROS), that advance the study of oxidative stress and cellular communication, were synthesized by functionalizing polyacrylamide nanoparticles with zinc(ii) porphyrin photosensitisers. Controlled ROS production was demonstrated in human mesenchymal stem cells (hMSCs) through (1) production of nanoparticles functionalized with varying percentages of Zn(ii) porphyrin and (2) modulating the number of doses of excitation light to internalized nanoparticles. hMSCs challenged with nanoparticles functionalized with increasing percentages of Zn(ii) porphyrin and high numbers of irradiations of excitation light were found to generate greater amounts of ROS. A novel dye, which is transformed into fluorescent 7-hydroxy-4-trifluoromethyl-coumarin in the presence of hydrogen peroxide, provided an indirect indicator for cumulative ROS production. The mitochondrial membrane potential was monitored to investigate the destructive effect of increased intracellular ROS production. Flow cytometric analysis of nanoparticle treated hMSCs suggested irradiation with excitation light signalled controlled apoptotic cell death, rather than uncontrolled necrotic cell death. Increased intracellular ROS production did not induce phenotypic changes in hMSC subcultures.Nanoparticles capable of generating controlled amounts of intracellular reactive oxygen species (ROS), that advance the study of oxidative stress and cellular communication, were synthesized by functionalizing polyacrylamide nanoparticles with zinc(ii) porphyrin photosensitisers. Controlled ROS production was demonstrated in human mesenchymal stem cells (hMSCs) through (1) production of nanoparticles functionalized with varying percentages of Zn(ii) porphyrin and (2) modulating the number of doses of excitation light to internalized nanoparticles. hMSCs challenged with nanoparticles functionalized with increasing percentages of Zn

  4. In situ generation of functionality in a reactive haloalkane-based ligand for the design of new porous coordination polymers.

    PubMed

    Kanoo, Prakash; Matsuda, Ryotaro; Sato, Hiroshi; Li, Liangchun; Jeon, Hyung Joon; Kitagawa, Susumu

    2013-10-01

    Herein, we report new porous coordination polymers (PCPs) via a facile synthetic approach called "in situ generation of functionality in the ligand". Upon a synthetic process of PCPs, a neutral (-CH2OH) or a cationic functionality (-CH2-[4,4'-bipyridine](+)) was generated on a isophthalate ligand from a reactive haloalkane (-CH2Br) moiety, affording two new PCPs. The PCPs have two-dimensional layered structures with large potential solvent-accessible voids for CO2 adsorption. PMID:24016100

  5. Cryptococcus neoformans capsule protects cell from oxygen reactive species generated by antimicrobial photodynamic inactivation

    NASA Astrophysics Data System (ADS)

    Prates, Renato Araujo; Hamblin, Michael R.; Kato, Ilka T.; Fuchs, Beth; Mylonakis, Eleytherios; Simões Ribeiro, Martha; Tegos, George

    2011-03-01

    Antimicrobial photodynamic inactivation (APDI) is based on the utilization of substances that can photosensitize biological tissues and are capable of being activated in the presence of light. Cryptococcus neoformans is an yeast surrounded by a capsule composed primarily of glucoronoxylomannan that plays an important role in its virulence. This yeast causes infection on skin, lungs and brain that can be associated with neurological sequelae and neurosurgical interventions, and its conventional treatment requires prolonged antifungal therapy, which presents important adverse effects. The aim of this study was to evaluate the protective effect of Cryptococcus neoformans capsule against reactive oxygen species generated by APDI. Cryptococcus neoformans KN99α, which is a strain able to produce capsule, and CAP59 that does not present capsule production were submitted to APDI using methylene blue (MB), rose bengal (RB), and pL-ce6 as photosensitizers (PS). Then microbial inactivation was evaluated by counting colony form units following APDI and confocal laser scanning microscopy (CLSM) illustrated localization as well as the preferential accumulation of PS into the fungal cells. C. neoformans KN99α was more resistant to APDI than CAP59 for all PSs tested. CLSM showed incorporation of MB and RB into the cytoplasm and a preferential uptake in mitochondria. A nuclear accumulation of MB was also observed. Contrarily, pL-ce6 appears accumulated in cell wall and cell membrane and minimal florescence was observed inside the fungal cells. In conclusion, the ability of C. neoformans to form capsule enhances survival following APDI.

  6. Determination of photochemically-generated reactive oxygen species in natural water.

    PubMed

    Zhan, Manjun

    2009-01-01

    Reactive oxygen species (ROS) can be produced by interactions between sunlight and light-absorbing substances in natural water environment. ROS may participate in the indirect photolysis of trace organic pollutants, therefore resulting in changes in their environmental fates and ecological risks in natural water systems. Bisphenol A (BPA), an endocrine-disrupting chemical, exits widely in natural waters. The photodegradation of BPA promoted by ROS (*OH, 1O2, HO2*/O2(*-)), which were produced on the excitation of ubiquitous constituents (such as nitrate ion, humic substances and Fe(III)-oxalate complexes) in natural water under simulated solar radiation was investigated. Both molecular probe method and electron spin resonance (ESR) test were used for the characterization of the generated ROS. It was found that *OH was photochemically produced in the presence of nitrate ions, humic substances and Fe(III)-oxalate complexes and that 102 was produced with the presence of humic substances. The steady-state concentrations of *OH was 1.27x10(-14) mol/L in a nitrate solution, and the second-order rate constant of BPA with *OH was 1.01 x 10(10) L/(mol x s). PMID:19634440

  7. Incorporating Geochemical And Microbial Kinetics In Reactive Transport Models For Generation Of Acid Rock Drainage

    NASA Astrophysics Data System (ADS)

    Andre, B. J.; Rajaram, H.; Silverstein, J.

    2010-12-01

    diffusion model at the scale of a single rock is developed incorporating the proposed kinetic rate expressions. Simulations of initiation, washout and AMD flows are discussed to gain a better understanding of the role of porosity, effective diffusivity and reactive surface area in generating AMD. Simulations indicate that flow boundary conditions control generation of acid rock drainage as porosity increases.

  8. Evidence for the generation of reactive oxygen species from hydroquinone and benzoquinone: Roles in arsenite oxidation.

    PubMed

    Qin, Wenxiu; Wang, Yujun; Fang, Guodong; Wu, Tongliang; Liu, Cun; Zhou, Dongmei

    2016-05-01

    Natural organic matter (NOM) significantly affects the fate, bioavailability, and toxicity of arsenic in the environment. In the present study, we investigated the oxidation of As(III) in the presence of hydroquinone (HQ) and benzoquinone (BQ), which were selected as model quinone moieties for NOM. It was found that As(III) was oxidized to As(V) in the presence of HQ or BQ at neutral conditions, and the oxidation efficiency of As(III) increased from 33% to 92% in HQ solutions and from 0 to 80% in BQ solutions with pH increasing from 6.5 to 8.5. The oxidation mechanism was further explored with electron spin resonance (ESR) technique. The results showed that semiquinone radicals (SQ(-)) were generated from the comproportionation reaction between BQ and HQ, which mediated the formation of superoxide anion (O2(-)), hydrogen peroxide (H2O2) and hydroxyl radical (OH). Both the SQ(-), H2O2 and OH contributed to the oxidation of As(III). The increase of pH favored the formation of SQ(-), and thus promoted the generation of reactive oxygen species (ROS) as well as As(III) oxidation. Increasing concentrations of HQ and BQ from 0.1 to 1.0 mM enhanced As(III) oxidation from 65% to 94% and from 10% to 53%, respectively. The findings of this study facilitate our understanding of the fate and transformation of As(III) in organic-rich aquatic environments and highlight quinone moieties as the potential oxidants for As(III) in the remediation of arsenic contaminated sites. PMID:26891359

  9. A Porous Tissue Engineering Scaffold Selectively Degraded by Cell-Generated Reactive Oxygen Species

    PubMed Central

    Martin, John R.; Gupta, Mukesh K.; Page, Jonathan M.; Yu, Fang; Davidson, Jeffrey M.; Guelcher, Scott A.

    2014-01-01

    Biodegradable tissue engineering scaffolds are commonly fabricated from poly(lactide-co-glycolide) (PLGA) or similar polyesters that degrade by hydrolysis. PLGA hydrolysis generates acidic breakdown products that trigger an accelerated, autocatalytic degradation mechanism that can create mismatched rates of biomaterial breakdown and tissue formation. Reactive oxygen species (ROS) are key mediators of cell function in both health and disease, especially at sites of inflammation and tissue healing, and induction of inflammation and ROS are natural components of the in vivo response to biomaterial implantation. Thus, polymeric biomaterials that are selectively degraded by cell-generated ROS may have potential for creating tissue engineering scaffolds with better matched rates of tissue in-growth and cell-mediated scaffold biodegradation. To explore this approach, a series of poly(thioketal) (PTK) urethane (PTK-UR) biomaterial scaffolds were synthesized that degrade specifically by an ROS-dependent mechanism. PTK-UR scaffolds had significantly higher compressive moduli than analogous poly(ester urethane) (PEUR) scaffolds formed from hydrolytically-degradable ester-based diols (p < 0.05). Unlike PEUR scaffolds, the PTK-UR scaffolds were stable under aqueous conditions out to 25 weeks but were selectively degraded by ROS, indicating that their biodegradation would be exclusively cell-mediated. The in vitro oxidative degradation rates of the PTK-URs followed first-order degradation kinetics, were significantly dependent on PTK composition (p < 0.05), and correlated to ROS concentration. In subcutaneous rat wounds, PTK-UR scaffolds supported cellular infiltration and granulation tissue formation, followed first-order degradation kinetics over 7 weeks, and produced significantly greater stenting of subcutaneous wounds compared to PEUR scaffolds. These combined results indicate that ROS-degradable PTK-UR tissue engineering scaffolds have significant advantages over analogous

  10. The phosphorylation status of extracellular-regulated kinase 1/2 in astrocytes and neurons from rat hippocampus determines the thrombin-induced calcium release and ROS generation.

    PubMed

    Zündorf, Gregor; Reiser, Georg

    2011-12-01

    Challenge of protease-activated receptors induces cytosolic Ca(2+) concentration ([Ca(2+) ](c)) increase, mitogen-activated protein kinase activation and reactive oxygen species (ROS) formation with a bandwidth of responses in individual cells. We detected in this study in situ the thrombin-induced [Ca(2+) ](c) rise and ROS formation in dissociated hippocampal astrocytes and neurons in a mixed culture. In identified cells, single cell responses were correlated with extracellular-regulated kinase (ERK)1/2 phosphorylation level. On average, in astrocytes, thrombin induced a transient [Ca(2+) ](c) rise with concentration-dependent increase in amplitude and extrusion rate and high ERK1/2 phosphorylation level. Correlation analysis of [Ca(2+) ](c) response characteristics of single astrocytes reveals that astrocytes with nuclear phosphoERK1/2 localization have a smaller Ca(2+) amplitude and extrusion rate compared with cells with a cytosolic phosphoERK1/2 localization. In naive neurons, without thrombin challenge, variable ERK1/2 phosphorylation patterns are observed. ROS were detected by hydroethidine. Only in neurons with increased ERK1/2 phosphorylation level, we see sustained intracellular rise in fluorescence of the dye lasting over several minutes. ROS formation was abolished by pre-incubation with the NADPH oxidase inhibitor apocynin. Additionally, thrombin induced an immediate, transient hydroethidine fluorescence increase. This was interpreted as NADPH oxidase-mediated O(2) (•-) -release into the extracellular milieu, because it was decreased by pre-incubation with apocynin, and could be eluted by superfusion. In conclusion, the phosphorylation status of ERK1/2 determines the thrombin-dependent [Ca(2+) ](c) increase and ROS formation and, thus, influences the capacity of thrombin to regulate neuroprotection or neurodegeneration. PMID:21988180

  11. Endothelial-cell apoptosis induced by cleaved high-molecular-weight kininogen (HKa) is matrix dependent and requires the generation of reactive oxygen species

    PubMed Central

    Sun, Danyu; McCrae, Keith R.

    2006-01-01

    High–molecular-weight kininogen (HK) is an abundant plasma protein that plays a central role in activation of the kallikrein-kinin system. Cleavage of HK by plasma kallikrein results in release of the nonapeptide bradykinin (BK), leaving behind cleaved high–molecular-weight kininogen (HKa). Previous studies have demonstrated that HKa induces apoptosis of proliferating endothelial cells and inhibits angiogenesis in vivo, activities mediated primarily through its domain 5. However, the mechanisms by which these effects occur are not well understood. Here, we demonstrate that HKa induces apoptosis of endothelial cells cultured on gelatin, vitronectin, fibronectin, or laminin but not collagen type I or IV. The ability of HKa to induce endothelial-cell apoptosis is dependent on the generation of intracellular reactive oxygen species and associated with depletion of glutathione and peroxidation of endothelial-cell lipids, effects that occur only in cells cultured on matrix proteins permissive for HKa-induced apoptosis. Finally, the ability of HKa to induce endothelial-cell apoptosis is blocked by the addition of reduced glutathione or N-acetylcysteine. These studies demonstrate a unique role for oxidant stress in mediating the activity of an antiangiogenic polypeptide and highlight the importance of the extracellular matrix in regulating endothelial-cell survival. PMID:16418331

  12. In vitro elastogenesis: instructing human vascular smooth muscle cells to generate an elastic fiber-containing extracellular matrix scaffold.

    PubMed

    Hinderer, Svenja; Shena, Nian; Ringuette, Léa-Jeanne; Hansmann, Jan; Reinhardt, Dieter P; Brucker, Sara Y; Davis, Elaine C; Schenke-Layland, Katja

    2015-06-01

    Elastic fibers are essential for the proper function of organs including cardiovascular tissues such as heart valves and blood vessels. Although (tropo)elastin production in a tissue-engineered construct has previously been described, the assembly to functional elastic fibers in vitro using human cells has been highly challenging. In the present study, we seeded primary isolated human vascular smooth muscle cells (VSMCs) onto 3D electrospun scaffolds and exposed them to defined laminar shear stress using a customized bioreactor system. Increased elastin expression followed by elastin deposition onto the electrospun scaffolds, as well as on newly formed fibers, was observed after six days. Most interestingly, we identified the successful deposition of elastogenesis-associated proteins, including fibrillin-1 and -2, fibulin-4 and -5, fibronectin, elastin microfibril interface located protein 1 (EMILIN-1) and lysyl oxidase (LOX) within our engineered constructs. Ultrastructural analyses revealed a developing extracellular matrix (ECM) similar to native human fetal tissue, which is composed of collagens, microfibrils and elastin. To conclude, the combination of a novel dynamic flow bioreactor and an electrospun hybrid polymer scaffold allowed the production and assembly of an elastic fiber-containing ECM. PMID:25784676

  13. Manipulation of environmental oxygen modifies reactive oxygen and nitrogen species generation during myogenesis

    PubMed Central

    McCormick, Rachel; Pearson, Timothy; Vasilaki, Aphrodite

    2016-01-01

    Regulated changes in reactive oxygen and nitrogen species (RONS) activities are important in maintaining the normal sequence and development of myogenesis. Both excessive formation and reduction in RONS have been shown to affect muscle differentiation in a negative way. Cultured cells are typically grown in 20% O2 but this is not an appropriate physiological concentration for a number of cell types, including skeletal muscle. The aim was to examine the generation of RONS in cultured skeletal muscle cells under a physiological oxygen concentration condition (6% O2) and determine the effect on muscle myogenesis. Primary mouse satellite cells were grown in 20% or 6% O2 environments and RONS activity was measured at different stages of myogenesis by real-time fluorescent microscopy using fluorescent probes with different specificities i.e. dihydroethidium (DHE), 4-amino-5-methylamino-2′,7′-difluorofluorescein diacetate (DAF-FM DA) and 5-(and-6)-chloromethyl-2′,7′ -dichlorodihydrofluorescein diacetate (CM-DCFH-DA). Data demonstrate that satellite cell proliferation increased when cells were grown in 6% O2 compared with 20% O2. Myoblasts grown in 20% O2 showed an increase in DCF fluorescence and DHE oxidation compared with myoblasts grown at 6% O2. Myotubes grown in 20% O2 also showed an increase in DCF and DAF-FM fluorescence and DHE oxidation compared with myotubes grown in 6% O2. The catalase and MnSOD contents were also increased in myoblasts and myotubes that were maintained in 20% O2 compared with myoblasts and myotubes grown in 6% O2. These data indicate that intracellular RONS activities in myoblasts and myotubes at rest are influenced by changes in environmental oxygen concentration and that the increased ROS may influence myogenesis in a negative manner. PMID:26827127

  14. Cancer Therapy by Catechins Involves Redox Cycling of Copper Ions and Generation of Reactive Oxygen species.

    PubMed

    Farhan, Mohd; Khan, Husain Yar; Oves, Mohammad; Al-Harrasi, Ahmed; Rehmani, Nida; Arif, Hussain; Hadi, Sheikh Mumtaz; Ahmad, Aamir

    2016-02-01

    Catechins, the dietary phytochemicals present in green tea and other beverages, are considered to be potent inducers of apoptosis and cytotoxicity to cancer cells. While it is believed that the antioxidant properties of catechins and related dietary agents may contribute to lowering the risk of cancer induction by impeding oxidative injury to DNA, these properties cannot account for apoptosis induction and chemotherapeutic observations. Catechin (C), epicatechin (EC), epigallocatechin (EGC) and epigallocatechin-3-gallate (EGCG) are the four major constituents of green tea. In this article, using human peripheral lymphocytes and comet assay, we show that C, EC, EGC and EGCG cause cellular DNA breakage and can alternatively switch to a prooxidant action in the presence of transition metals such as copper. The cellular DNA breakage was found to be significantly enhanced in the presence of copper ions. Catechins were found to be effective in providing protection against oxidative stress induced by tertbutylhydroperoxide, as measured by oxidative DNA breakage in lymphocytes. The prooxidant action of catechins involved production of hydroxyl radicals through redox recycling of copper ions. We also determined that catechins, particularly EGCG, inhibit proliferation of breast cancer cell line MDA-MB-231 leading to a prooxidant cell death. Since it is well established that tissue, cellular and serum copper levels are considerably elevated in various malignancies, cancer cells would be more subject to redox cycling between copper ions and catechins to generate reactive oxygen species (ROS) responsible for DNA breakage. Such a copper dependent prooxidant cytotoxic mechanism better explains the anticancer activity and preferential cytotoxicity of dietary phytochemicals against cancer cells. PMID:26861392

  15. Manipulation of environmental oxygen modifies reactive oxygen and nitrogen species generation during myogenesis.

    PubMed

    McCormick, Rachel; Pearson, Timothy; Vasilaki, Aphrodite

    2016-08-01

    Regulated changes in reactive oxygen and nitrogen species (RONS) activities are important in maintaining the normal sequence and development of myogenesis. Both excessive formation and reduction in RONS have been shown to affect muscle differentiation in a negative way. Cultured cells are typically grown in 20% O2 but this is not an appropriate physiological concentration for a number of cell types, including skeletal muscle. The aim was to examine the generation of RONS in cultured skeletal muscle cells under a physiological oxygen concentration condition (6% O2) and determine the effect on muscle myogenesis. Primary mouse satellite cells were grown in 20% or 6% O2 environments and RONS activity was measured at different stages of myogenesis by real-time fluorescent microscopy using fluorescent probes with different specificities i.e. dihydroethidium (DHE), 4-amino-5-methylamino-2',7'-difluorofluorescein diacetate (DAF-FM DA) and 5-(and-6)-chloromethyl-2',7' -dichlorodihydrofluorescein diacetate (CM-DCFH-DA). Data demonstrate that satellite cell proliferation increased when cells were grown in 6% O2 compared with 20% O2. Myoblasts grown in 20% O2 showed an increase in DCF fluorescence and DHE oxidation compared with myoblasts grown at 6% O2. Myotubes grown in 20% O2 also showed an increase in DCF and DAF-FM fluorescence and DHE oxidation compared with myotubes grown in 6% O2. The catalase and MnSOD contents were also increased in myoblasts and myotubes that were maintained in 20% O2 compared with myoblasts and myotubes grown in 6% O2. These data indicate that intracellular RONS activities in myoblasts and myotubes at rest are influenced by changes in environmental oxygen concentration and that the increased ROS may influence myogenesis in a negative manner. PMID:26827127

  16. Cancer Therapy by Catechins Involves Redox Cycling of Copper Ions and Generation of Reactive Oxygen Species

    PubMed Central

    Farhan, Mohd; Khan, Husain Yar; Oves, Mohammad; Al-Harrasi, Ahmed; Rehmani, Nida; Arif, Hussain; Hadi, Sheikh Mumtaz; Ahmad, Aamir

    2016-01-01

    Catechins, the dietary phytochemicals present in green tea and other beverages, are considered to be potent inducers of apoptosis and cytotoxicity to cancer cells. While it is believed that the antioxidant properties of catechins and related dietary agents may contribute to lowering the risk of cancer induction by impeding oxidative injury to DNA, these properties cannot account for apoptosis induction and chemotherapeutic observations. Catechin (C), epicatechin (EC), epigallocatechin (EGC) and epigallocatechin-3-gallate (EGCG) are the four major constituents of green tea. In this article, using human peripheral lymphocytes and comet assay, we show that C, EC, EGC and EGCG cause cellular DNA breakage and can alternatively switch to a prooxidant action in the presence of transition metals such as copper. The cellular DNA breakage was found to be significantly enhanced in the presence of copper ions. Catechins were found to be effective in providing protection against oxidative stress induced by tertbutylhydroperoxide, as measured by oxidative DNA breakage in lymphocytes. The prooxidant action of catechins involved production of hydroxyl radicals through redox recycling of copper ions. We also determined that catechins, particularly EGCG, inhibit proliferation of breast cancer cell line MDA-MB-231 leading to a prooxidant cell death. Since it is well established that tissue, cellular and serum copper levels are considerably elevated in various malignancies, cancer cells would be more subject to redox cycling between copper ions and catechins to generate reactive oxygen species (ROS) responsible for DNA breakage. Such a copper dependent prooxidant cytotoxic mechanism better explains the anticancer activity and preferential cytotoxicity of dietary phytochemicals against cancer cells. PMID:26861392

  17. Nucleic acid reactivity : challenges for next-generation semiempirical quantum models

    PubMed Central

    Huang, Ming; Giese, Timothy J.; York, Darrin M.

    2016-01-01

    Semiempirical quantum models are routinely used to study mechanisms of RNA catalysis and phosphoryl transfer reactions using combined quantum mechanical/molecular mechanical methods. Herein, we provide a broad assessment of the performance of existing semiempirical quantum models to describe nucleic acid structure and reactivity in order to quantify their limitations and guide the development of next-generation quantum models with improved accuracy. Neglect of diatomic diffierential overlap (NDDO) and self-consistent density-functional tight-binding (SCC-DFTB) semiempirical models are evaluated against high-level quantum mechanical benchmark calculations for seven biologically important data sets. The data sets include: proton affinities, polarizabilities, nucleobase dimer interactions, dimethyl phosphate anion, nucleoside sugar and glycosidic torsion conformations, and RNA phosphoryl transfer model reactions. As an additional baseline, comparisons are made with several commonly used density-functional models, including M062X and B3LYP (in some cases with dispersion corrections). The results show that, among the semiempirical models examined, the AM1/d-PhoT model is the most robust at predicting proton affinities. AM1/d-PhoT and DFTB3-3ob/OPhyd reproduce the MP2 potential energy surfaces of 6 associative RNA phosphoryl transfer model reactions reasonably well. Further, a recently developed linear-scaling “modified divide-and-conquer” model exhibits the most accurate results for binding energies of both hydrogen bonded and stacked nucleobase dimers. The semiempirical models considered here are shown to underestimate the isotropic polarizabilities of neutral molecules by approximately 30%. The semiempirical models also fail to adequately describe torsion profiles within the dimethyl phosphate anion, the nucleoside sugar ring puckers, and the rotations about the nucleoside glycosidic bond. The modeling of pentavalent phosphorus, particularly with thio

  18. Nucleic acid reactivity: challenges for next-generation semiempirical quantum models.

    PubMed

    Huang, Ming; Giese, Timothy J; York, Darrin M

    2015-07-01

    Semiempirical quantum models are routinely used to study mechanisms of RNA catalysis and phosphoryl transfer reactions using combined quantum mechanical (QM)/molecular mechanical methods. Herein, we provide a broad assessment of the performance of existing semiempirical quantum models to describe nucleic acid structure and reactivity to quantify their limitations and guide the development of next-generation quantum models with improved accuracy. Neglect of diatomic differential overlap and self-consistent density-functional tight-binding semiempirical models are evaluated against high-level QM benchmark calculations for seven biologically important datasets. The datasets include: proton affinities, polarizabilities, nucleobase dimer interactions, dimethyl phosphate anion, nucleoside sugar and glycosidic torsion conformations, and RNA phosphoryl transfer model reactions. As an additional baseline, comparisons are made with several commonly used density-functional models, including M062X and B3LYP (in some cases with dispersion corrections). The results show that, among the semiempirical models examined, the AM1/d-PhoT model is the most robust at predicting proton affinities. AM1/d-PhoT and DFTB3-3ob/OPhyd reproduce the MP2 potential energy surfaces of 6 associative RNA phosphoryl transfer model reactions reasonably well. Further, a recently developed linear-scaling "modified divide-and-conquer" model exhibits the most accurate results for binding energies of both hydrogen bonded and stacked nucleobase dimers. The semiempirical models considered here are shown to underestimate the isotropic polarizabilities of neutral molecules by approximately 30%. The semiempirical models also fail to adequately describe torsion profiles for the dimethyl phosphate anion, the nucleoside sugar ring puckers, and the rotations about the nucleoside glycosidic bond. The modeling of pentavalent phosphorus, particularly with thio substitutions often used experimentally as mechanistic

  19. FRAS1-related extracellular matrix 3 (FREM3) single-nucleotide polymorphism effects on gene expression, amygdala reactivity and perceptual processing speed: An accelerated aging pathway of depression risk

    PubMed Central

    Nikolova, Yuliya S.; Iruku, Swetha P.; Lin, Chien-Wei; Conley, Emily Drabant; Puralewski, Rachel; French, Beverly; Hariri, Ahmad R.; Sibille, Etienne

    2015-01-01

    The A allele of the FRAS1-related extracellular matrix protein 3 (FREM3) rs7676614 single nucleotide polymorphism (SNP) was linked to major depressive disorder (MDD) in an early genome-wide association study (GWAS), and to symptoms of psychomotor retardation in a follow-up investigation. In line with significant overlap between age- and depression-related molecular pathways, parallel work has shown that FREM3 expression in postmortem human brain decreases with age. Here, we probe the effect of rs7676614 on amygdala reactivity and perceptual processing speed, both of which are altered in depression and aging. Amygdala reactivity was assessed using a face-matching BOLD fMRI paradigm in 365 Caucasian participants in the Duke Neurogenetics Study (DNS) (192 women, mean age 19.7 ± 1.2). Perceptual processing speed was indexed by reaction times in the same task and the Trail Making Test (TMT). The effect of rs7676614 on FREM3 mRNA brain expression levels was probed in a postmortem cohort of 169 Caucasian individuals (44 women, mean age 50.8 ± 14.9). The A allele of rs7676614 was associated with blunted amygdala reactivity to faces, slower reaction times in the face-matching condition (p < 0.04), as well as marginally slower performance on TMT Part B (p = 0.056). In the postmortem cohort, the T allele of rs6537170 (proxy for the rs7676614 A allele), was associated with trend-level reductions in gene expression in Brodmann areas 11 and 47 (p = 0.066), reminiscent of patterns characteristic of older age. The low-expressing allele of another FREM3 SNP (rs1391187) was similarly associated with reduced amygdala reactivity and slower TMT Part B speed, in addition to reduced BA47 activity and extraversion (p < 0.05). Together, these results suggest common genetic variation associated with reduced FREM3 expression may confer risk for a subtype of depression characterized by reduced reactivity to environmental stimuli and slower perceptual processing speed, possibly suggestive of

  20. Procyanidins from Nelumbo nucifera Gaertn. Seedpod induce autophagy mediated by reactive oxygen species generation in human hepatoma G2 cells.

    PubMed

    Duan, Yuqing; Xu, Hui; Luo, Xiaoping; Zhang, Haihui; He, Yuanqing; Sun, Guibo; Sun, Xiaobo

    2016-04-01

    In this study, autophagic effect of procyanidins from lotus (Nelumbo nucifera Gaertn.) seedpod (LSPCs) on human hepatoma G2 (HepG2) cells, and the inherent correlation between autophagic levels and reactive oxygen species (ROS) generation were investigated. The results showed that LSPCs increased monodansylcadaverine (MDC) fluorescence intensity and LC3-I/LC3-II conversion in HepG2 cells. In addition, the typically autophagic characteristics (autophagosomes and autolysosomes) were observed in LSPCs-treated cells, but not found in the cells treated with autophagy inhibitor 3-methyladenine (3-MA). Furthermore, the elevated ROS level was in line with the increasing of autophagy activation caused by LSPCs, however, both 3-MA and the ROS scavenger N-acetylcyteine (NAC) inhibitors effectively suppressed the autophagy and ROS generation triggered by LSPCs. As a result, these results indicated that LSPCs induced HepG2 cell autophagy in a time- and dose-dependent manner, and promoted reactive oxygen species (ROS) generation on HepG2 cells. Moreover, we found that LSPCs caused DNA damage, S phase arrest and the decrement of mitochondria membrane potential (MMP) which were associated with ROS generation. In summary, our findings demonstrated that the LSPCs-induced autophagy and autophagic cell death were triggered by the ROS generation in HepG2 cells, which might be associated with ROS generation through the mitochondria-dependent signaling way. PMID:27044822

  1. Interaction of Platelet Activating Factor, Reactive Oxygen Species Generated by Xanthine Oxidase, and Leukocytes in the Generation of Hepatic Injury After Shock/Resuscitation

    PubMed Central

    Yamakawa, Yasuhiko; Takano, Manabu; Patel, Mayur; Tien, Nevin; Takada, Tadahiro; Bulkley, Gregory B.

    2000-01-01

    Objective To evaluate the putative relation of platelet activating factor (PAF), xanthine oxidase, reactive oxidants, and leukocytes in the pathogenesis of hepatic injury after shock/resuscitation (S/R) in vivo. Background Reactive oxygen metabolites generated by xanthine oxidase at reperfusion have been found to trigger postischemic injury in many organs, including the liver. However, the precise linear sequence of the mechanism of consequent hepatic injury after S/R remains to be characterized. Methods Unheparinized male rats were bled to a mean blood pressure of 45 ± 3 mmHg. After 2 hours of shock, they were resuscitated by reinfusion of shed blood (anticoagulated with citrate-phosphate-dextrose) and crystalloid and observed for the next 6 or 24 hours. Results S/R caused the oxidation of hepatic glutathione and generated centrolobular leukocyte accumulation at 6 hours, followed by predominantly centrolobular hepatocellular injury at 24 hours. Each of these components was attenuated by PAF inhibition with WEB 2170, xanthine oxidase inhibition with allopurinol, antioxidant treatment with N-acetylcysteine, or severe leukopenia induced by vinblastine. In each case, the degree of leukocyte accumulation at 6 hours correlated with the hepatocellular injury seen at 24 hours. However, xanthine oxidase inhibition with allopurinol failed to attenuate further the small level of residual hepatocellular injury seen in leukopenic rats. Conclusion These findings suggest that reactive oxidants generated by xanthine oxidase at reperfusion, stimulated by PAF, mediate hepatocellular injury by triggering leukocyte accumulation, primarily within the centrolobular sinusoids. PMID:10714632

  2. From Microbiology to Cancer Biology: The Rid Protein Family Prevents Cellular Damage Caused by Endogenously Generated Reactive Nitrogen Species

    PubMed Central

    Downs, Diana M.; Ernst, Dustin C.

    2015-01-01

    Summary The Rid family of proteins is highly conserved and broadly distributed throughout the domains of life. Genetic and biochemical studies, primarily in Salmonella enterica, have defined a role for RidA in responding to endogenously generated reactive metabolites. The data show that 2-aminoacrylate (2AA), a reactive enamine intermediate generated by some pyridoxal 5′-phosphate (PLP)-dependent enzymes, accumulates in the absence of RidA. The accumulation of 2AA leads to covalent modification and inactivation of several enzymes involved in essential metabolic processes. This review describes the 2AA hydrolyzing activity of RidA and the effect of this biochemical activity on the metabolic network, which impacts organism fitness. The reported activity of RidA and the consequences encountered in vivo when RidA is absent have challenged fundamental assumptions in enzymology, biochemistry and cell metabolism regarding the fate of transiently-generated reactive enamine intermediates. The current understanding of RidA in Salmonella and the broad distribution of Rid family proteins provide exciting opportunities for future studies to define metabolic roles of Rid family members from microbes to man. PMID:25620221

  3. Photovoltaic solar system connected to the electric power grid operating as active power generator and reactive power compensator

    SciTech Connect

    Albuquerque, Fabio L.; Moraes, Adelio J.; Guimaraes, Geraldo C.; Sanhueza, Sergio M.R.; Vaz, Alexandre R.

    2010-07-15

    In the case of photovoltaic (PV) systems acting as distributed generation (DG) systems, the DC energy that is produced is fed to the grid through the power-conditioning unit (inverter). The majority of contemporary inverters used in DG systems are current source inverters (CSI) operating at unity power factor. If, however, we assume that voltage source inverters (VSI) can replace CSIs, we can generate reactive power proportionally to the remaining unused capacity at any given time. According to the theory of instantaneous power, the inverter reactive power can be regulated by changing the amplitude of its output voltage. In addition, the inverter active power can be adjusted by modifying the phase angle of its output voltage. Based on such theory, both the active power supply and the reactive power compensation (RPC) can be carried out simultaneously. When the insolation is weak or the PV modules are inoperative at night, the RPC feature of a PV system can still be used to improve the inverter utilisation factor. Some MATLAB simulation results are included here to show the feasibility of the method. (author)

  4. Identification of cross-reactive single-domain antibodies against serum albumin using next-generation DNA sequencing.

    PubMed

    Henry, Kevin A; Tanha, Jamshid; Hussack, Greg

    2015-10-01

    Antibodies that cross-react with multiple isoforms or homologue of a given protein are often desirable, especially in therapeutic applications. Here, we report the identification of several unique, clonally unrelated, single-domain antibodies (sdAbs) that bind to multiple serum albumin orthologues (human, rhesus, rat and mouse) with low-to-medium nanomolar affinity from a llama immunized only with human serum albumin. Using single-round panning of a phage-displayed sdAb library against serum albumins and next-generation DNA sequencing, we were able to predict patterns of sdAb reactivity to the albumins of different species with ∼90% accuracy. We expect this strategy to be generally applicable for identifying cross-reactive sdAbs, particularly when these exist at low frequency and/or are poorly enriched by panning. Moreover, the sdAbs identified here are of potential interest for serum half-life extension of biologics. PMID:26319004

  5. Lysophosphatidic acid induces reactive oxygen species generation by activating protein kinase C in PC-3 human prostate cancer cells

    SciTech Connect

    Lin, Chu-Cheng; Lin, Chuan-En; Lin, Yueh-Chien; Ju, Tsai-Kai; Huang, Yuan-Li; Lee, Ming-Shyue; Chen, Jiun-Hong; Lee, Hsinyu

    2013-11-01

    Highlights: •LPA induces ROS generation through LPA{sub 1} and LPA{sub 3}. •LPA induces ROS generation by activating PLC. •PKCζ mediates LPA-induced ROS generation. -- Abstract: Prostate cancer is one of the most frequently diagnosed cancers in males, and PC-3 is a cell model popularly used for investigating the behavior of late stage prostate cancer. Lysophosphatidic acid (LPA) is a lysophospholipid that mediates multiple behaviors in cancer cells, such as proliferation, migration and adhesion. We have previously demonstrated that LPA enhances vascular endothelial growth factor (VEGF)-C expression in PC-3 cells by activating the generation of reactive oxygen species (ROS), which is known to be an important mediator in cancer progression. Using flow cytometry, we showed that LPA triggers ROS generation within 10 min and that the generated ROS can be suppressed by pretreatment with the NADPH oxidase (Nox) inhibitor diphenylene iodonium. In addition, transfection with LPA{sub 1} and LPA{sub 3} siRNA efficiently blocked LPA-induced ROS production, suggesting that both receptors are involved in this pathway. Using specific inhibitors and siRNA, phospholipase C (PLC) and protein kinase C (PKC) were also suggested to participate in LPA-induced ROS generation. Overall, we demonstrated that LPA induces ROS generation in PC-3 prostate cancer cells and this is mediated through the PLC/PKC/Nox pathway.

  6. Calcium-dependent trichosanthin-induced generation of reactive oxygen species involved in apoptosis of human choriocarcinoma cells

    NASA Astrophysics Data System (ADS)

    Zhang, Chunyang; Ma, Hui; Chen, Die Yan

    2001-04-01

    The type-I ribosome-inactivating protein trichosanthin (TCS) has a broad spectrum of biological and pharmacological activities, including abortifacient, anti-tumor and anti-HIV. We found for the first time that TCS induced production of reactive oxygen species (ROS) in JAR cells by using fluorescent probe 2',7'-dichlorofluorescin diacetate with confocal laser scanning microscopy. TCS-induced ROS showed dependence on the increase in intracellular calcium and on the presence of extracellular calcium. The production of ROS increased rapidly after the application of TCS, which paralleled TCS-indued increase in intracellular calcium monitored using fluo 3-AM, suggesting that TCS-induced ROS might mediate by the increase in intracellular Ca2PLU concentration. Simultaneous observation of the nuclear morphological changes and production of ROS in JAR cells with two-photon laser scanning microscopy and confocal laser scanning microscopy revealed that ROS involved in the apoptosis of JAR cells, which was confirmed by that antioxidant (alpha) -tocopherol prevented TCS-induced ROS formation and cell death. The finding that calcium-dependent TCS-induced ROS involved in the apoptosis of JAR cells might provide new insight into the anti-tumor and anti-HIV mechanism of TCS.

  7. An assay for pro-oxidant reactivity based on phenoxyl radicals generated by laccase.

    PubMed

    Moţ, Augustin Cătălin; Coman, Cristina; Miron, Carmen; Damian, Grigore; Sarbu, Costel; Silaghi-Dumitrescu, Radu

    2014-01-15

    A transient species may be detected with UV-vis and EPR spectroscopy during turnover of a laccase with quercetin; this species is assigned as a quercetin-derived radical, based on EPR spectra as well the observed UV-vis similarities (a 540nm centred band) with previously reported data. The rates of formation and decay of this species correlate well (r=0.9946) with the pro-oxidant reactivity manifested by flavonoids in the presence of laccase. An assay for the pro-oxidant reactivity of natural products is hence proposed based on the results reported here; its application is demonstrated for a series of pure compounds as well as for several propolis extracts. This assay has the advantages of using a biologically relevant process (haemoglobin oxidation), and not requiring the addition of oxidising agents such as peroxide or superoxide. Correlations, or the lack thereof, between the pro-oxidant parameters and the redox potentials, antioxidant capacities and lipophilicities, were analysed. The laccase employed in our study does display reactivity-related similarities to a range of other proteins, including human plasma ceruloplasmin. PMID:24054233

  8. Direct and Indirect Co-culture of Chondrocytes and Mesenchymal Stem Cells for the Generation of Polymer/Extracellular Matrix Hybrid Constructs

    PubMed Central

    Levorson, Erica J.; Santoro, Marco; Kasper, F. Kurtis; Mikos, Antonios G.

    2014-01-01

    In this work, the influence of direct cell-cell contact in co-cultures of mesenchymal stem cells (MSCs) and chondrocytes for the improved deposition of cartilage-like extracellular matrix (ECM) within nonwoven fibrous poly(∊ -caprolactone) (PCL) scaffolds was examined. To this end, chondrocytes and MSCs were either co-cultured in direct contact by mixing on a single PCL scaffold or via indirect co-culture whereby the two cell types were seeded on separate scaffolds which were then cultured together in the same system either statically or under media perfusion in a bioreactor. In static cultures, the chondrocyte scaffold of an indirectly co-cultured group generated significantly greater amounts of glycosaminoglycan and collagen than the direct co-culture group initially seeded with the same number of chondrocytes. Furthermore, improved ECM production was linked to greater cellular proliferation and distribution throughout the scaffold in static culture. In perfusion cultures, flow had a significant effect on the proliferation of the chondrocytes. The ECM contents within the chondrocyte containing scaffolds of the indirect co-culture groups either approximated or surpassed the amounts generated within the direct co-culture group. Additionally, within bioreactor culture there were indications that chondrocytes had an influence on the chondrogenesis of MSCs as evidenced by increases in cartilaginous ECM synthetic capacity. This work demonstrates that it is possible to generate PCL/ECM hybrid scaffolds for cartilage regeneration by utilizing the factors secreted by two different cell types, chondrocytes and MSCs, even in the absence of juxtacrine signaling. PMID:24365703

  9. Functional implications of mitochondrial reactive oxygen species generated by oncogenic viruses

    PubMed Central

    Choi, Young Bong; Harhaj, Edward William

    2014-01-01

    Between 15–20% of human cancers are associated with infection by oncogenic viruses. Oncogenic viruses, including HPV, HBV, HCV and HTLV-1, target mitochondria to influence cell proliferation and survival. Oncogenic viral gene products also trigger the production of reactive oxygen species which can elicit oxidative DNA damage and potentiate oncogenic host signaling pathways. Viral oncogenes may also subvert mitochondria quality control mechanisms such as mitophagy and metabolic adaptation pathways to promote virus replication. Here, we will review recent progress on viral regulation of mitophagy and metabolic adaptation and their roles in viral oncogenesis. PMID:25580106

  10. Oxidation-extraction spectrometry of reactive oxygen species (ROS) generated by chlorophyllin magnesium (Chl-Mg) under ultrasonic irradiation

    NASA Astrophysics Data System (ADS)

    Guo, Yuwei; Cheng, Chunping; Wang, Jun; Jin, Xudong; Liu, Bin; Wang, Zhiqiu; Gao, Jingqun; Kang, Pingli

    2011-09-01

    In order to examine the mechanism and process of sonodynamic reaction, the chlorophyllin magnesium (Chl-Mg) acting as a sonosensitizer was irradiated by ultrasound, and the generation of reactive oxygen species (ROS) were detected by the method of oxidation-extraction spectrometry (OES). That is, under ultrasonic irradiation in the presence of Chl-Mg, the 1,5-diphenyl carbazide (DPCI) is oxidized by generated ROS into 1,5-diphenyl carbazone (DPCO), which can be extracted by mixed organic solvent and display a obvious visible absorption at 563 nm wavelength. Besides, the generation conditions of ROS were also reviewed. The results demonstrated that the quantities of generated ROS increased with the increase of ultrasonic irradiation time, Chl-Mg concentration and DPCI concentration. Finally, several radical scavengers (l-Histidine (His), 2,6-Di-tert-butyl-methylphenol (BHT) and Vitamin C (VC)) were used to determine the kind of the generated ROS. It was found that at least the hydroxyl radical (OH) and singlet oxygen ( 1O 2) were generated in the presence of Chl-Mg under ultrasonic irradiation. It is wish that this paper might offer some valuable references for the study on the mechanism of SDT and the application of Chl-Mg in tumor treatment.

  11. Next-generation re-sequencing of genes involved in increased platelet reactivity in diabetic patients on acetylsalicylic acid.

    PubMed

    Postula, Marek; Janicki, Piotr K; Eyileten, Ceren; Rosiak, Marek; Kaplon-Cieslicka, Agnieszka; Sugino, Shigekazu; Wilimski, Radosław; Kosior, Dariusz A; Opolski, Grzegorz; Filipiak, Krzysztof J; Mirowska-Guzel, Dagmara

    2016-06-01

    The objective of this study was to investigate whether rare missense genetic variants in several genes related to platelet functions and acetylsalicylic acid (ASA) response are associated with the platelet reactivity in patients with diabetes type 2 (T2D) on ASA therapy. Fifty eight exons and corresponding introns of eight selected genes, including PTGS1, PTGS2, TXBAS1, PTGIS, ADRA2A, ADRA2B, TXBA2R, and P2RY1 were re-sequenced in 230 DNA samples from T2D patients by using a pooled PCR amplification and next-generation sequencing by Illumina HiSeq2000. The observed non-synonymous variants were confirmed by individual genotyping of 384 DNA samples comprising of the individuals from the original discovery pools and additional verification cohort of 154 ASA-treated T2DM patients. The association between investigated phenotypes (ASA induced changes in platelets reactivity by PFA-100, VerifyNow and serum thromboxane B2 level [sTxB2]), and accumulation of rare missense variants (genetic burden) in investigated genes was tested using statistical collapsing tests. We identified a total of 35 exonic variants, including 3 common missense variants, 15 rare missense variants, and 17 synonymous variants in 8 investigated genes. The rare missense variants exhibited statistically significant difference in the accumulation pattern between a group of patients with increased and normal platelet reactivity based on PFA-100 assay. Our study suggests that genetic burden of the rare functional variants in eight genes may contribute to differences in the platelet reactivity measured with the PFA-100 assay in the T2DM patients treated with ASA. PMID:26599574

  12. A LAIR-1 insertion generates broadly reactive antibodies against malaria variant antigens

    PubMed Central

    Abdi, Abdirahman; Perez, Mathilde Foglierini; Geiger, Roger; Tully, Claire Maria; Jarrossay, David; Maina Ndungu, Francis; Wambua, Juliana; Bejon, Philip; Fregni, Chiara Silacci; Fernandez-Rodriguez, Blanca; Barbieri, Sonia; Bianchi, Siro; Marsh, Kevin; Thathy, Vandana; Corti, Davide; Sallusto, Federica

    2016-01-01

    Plasmodium falciparum antigens expressed on the surface of infected erythrocytes are important targets of naturally acquired immunity against malaria, but their high number and variability provide the pathogen with a powerful means of escape from host antibodies1–4. Although broadly reactive antibodies against these antigens could be useful as therapeutics and in vaccine design, their identification has proven elusive. Here, we report the isolation of human monoclonal antibodies that recognize erythrocytes infected by different P. falciparum isolates and opsonize these cells by binding to members of the RIFIN family. These antibodies acquired broad reactivity through a novel mechanism of insertion of a large DNA fragment between the V and DJ segments. The insert, which is both necessary and sufficient for binding to RIFINs, encodes the entire 100 amino acid collagen-binding domain of LAIR-1, an Ig superfamily inhibitory receptor encoded on chromosome 19. In each of the two donors studied, the antibodies are produced by a single expanded B cell clone and carry distinct somatic mutations in the LAIR-1 domain that abolish binding to collagen and increase binding to infected erythrocytes. These findings illustrate, with a biologically relevant example, a novel mechanism of antibody diversification by interchromosomal DNA transposition and demonstrate the existence of conserved epitopes that may be suitable candidates for the development of a malaria vaccine. PMID:26700814

  13. A LAIR1 insertion generates broadly reactive antibodies against malaria variant antigens.

    PubMed

    Tan, Joshua; Pieper, Kathrin; Piccoli, Luca; Abdi, Abdirahman; Foglierini, Mathilde; Geiger, Roger; Tully, Claire Maria; Jarrossay, David; Ndungu, Francis Maina; Wambua, Juliana; Bejon, Philip; Fregni, Chiara Silacci; Fernandez-Rodriguez, Blanca; Barbieri, Sonia; Bianchi, Siro; Marsh, Kevin; Thathy, Vandana; Corti, Davide; Sallusto, Federica; Bull, Peter; Lanzavecchia, Antonio

    2016-01-01

    Plasmodium falciparum antigens expressed on the surface of infected erythrocytes are important targets of naturally acquired immunity against malaria, but their high number and variability provide the pathogen with a powerful means of escape from host antibodies. Although broadly reactive antibodies against these antigens could be useful as therapeutics and in vaccine design, their identification has proven elusive. Here we report the isolation of human monoclonal antibodies that recognize erythrocytes infected by different P. falciparum isolates and opsonize these cells by binding to members of the RIFIN family. These antibodies acquired broad reactivity through a novel mechanism of insertion of a large DNA fragment between the V and DJ segments. The insert, which is both necessary and sufficient for binding to RIFINs, encodes the entire 98 amino acid collagen-binding domain of LAIR1, an immunoglobulin superfamily inhibitory receptor encoded on chromosome 19. In each of the two donors studied, the antibodies are produced by a single expanded B-cell clone and carry distinct somatic mutations in the LAIR1 domain that abolish binding to collagen and increase binding to infected erythrocytes. These findings illustrate, with a biologically relevant example, a novel mechanism of antibody diversification by interchromosomal DNA transposition and demonstrate the existence of conserved epitopes that may be suitable candidates for the development of a malaria vaccine. PMID:26700814

  14. Extracellular calcium sensing and extracellular calcium signaling

    NASA Technical Reports Server (NTRS)

    Brown, E. M.; MacLeod, R. J.; O'Malley, B. W. (Principal Investigator)

    2001-01-01

    The cloning of a G protein-coupled extracellular Ca(2+) (Ca(o)(2+))-sensing receptor (CaR) has elucidated the molecular basis for many of the previously recognized effects of Ca(o)(2+) on tissues that maintain systemic Ca(o)(2+) homeostasis, especially parathyroid chief cells and several cells in the kidney. The availability of the cloned CaR enabled the development of DNA and antibody probes for identifying the CaR's mRNA and protein, respectively, within these and other tissues. It also permitted the identification of human diseases resulting from inactivating or activating mutations of the CaR gene and the subsequent generation of mice with targeted disruption of the CaR gene. The characteristic alterations in parathyroid and renal function in these patients and in the mice with "knockout" of the CaR gene have provided valuable information on the CaR's physiological roles in these tissues participating in mineral ion homeostasis. Nevertheless, relatively little is known about how the CaR regulates other tissues involved in systemic Ca(o)(2+) homeostasis, particularly bone and intestine. Moreover, there is evidence that additional Ca(o)(2+) sensors may exist in bone cells that mediate some or even all of the known effects of Ca(o)(2+) on these cells. Even more remains to be learned about the CaR's function in the rapidly growing list of cells that express it but are uninvolved in systemic Ca(o)(2+) metabolism. Available data suggest that the receptor serves numerous roles outside of systemic mineral ion homeostasis, ranging from the regulation of hormonal secretion and the activities of various ion channels to the longer term control of gene expression, programmed cell death (apoptosis), and cellular proliferation. In some cases, the CaR on these "nonhomeostatic" cells responds to local changes in Ca(o)(2+) taking place within compartments of the extracellular fluid (ECF) that communicate with the outside environment (e.g., the gastrointestinal tract). In others

  15. Antioxidant defence systems and generation of reactive oxygen species in osteosarcoma cells with defective mitochondria: effect of selenium.

    PubMed

    Wojewoda, Marta; Duszyński, Jerzy; Szczepanowska, Joanna

    2010-01-01

    Mitochondrial diseases originate from mutations in mitochondrial or nuclear genes encoding for mitochondrial proteome. Neurogenic muscle weakness, ataxia and retinitis pigmentosa (NARP) syndrome is associated with the T8993G transversion in ATP6 gene which results in substitution at the very conservative site in the subunit 6 of mitochondrial ATP synthase. Defects in the mitochondrial respiratory chain and the ATPase are considered to be accompanied by changes in the generation of reactive oxygen species (ROS). This study aimed to elucidate effects of selenium on ROS and antioxidant system of NARP cybrid cells with 98% of T8993G mutation load. We found that selenium decreased ROS generation and increased the level and activity of antioxidant enzymes such as glutathione peroxidase (GPx) and thioredoxin reductase (TrxR). Therefore, we propose selenium to be a promising therapeutic agent not only in the case of NARP syndrome but also other diseases associated with mitochondrial dysfunctions and oxidative stress. PMID:20138159

  16. Oxidation of Levafix CA reactive azo-dyes in industrial wastewater of textile dyeing by electro-generated Fenton's reagent.

    PubMed

    El-Desoky, Hanaa S; Ghoneim, Mohamed M; El-Sheikh, Ragaa; Zidan, Naglaa M

    2010-03-15

    The indirect electrochemical removal of pollutants from effluents has become an attractive method in recent years. Removal (decolorization and mineralization) of Levafix Blue CA and Levafix Red CA reactive azo-dyes from aqueous media by electro-generated Fenton's reagent (Fe(2+)/H(2)O(2)) using a reticulated vitreous carbon cathode and a platinum gauze anode was optimized. Progress of oxidation (decolorization and mineralization) of the investigated azo-dyes with time of electro-Fenton's reaction was monitored by UV-visible absorbance measurements, Chemical oxygen demand (COD) removal and HPLC analysis. The results indicated that the electro-Fenton's oxidation system is efficient for treatment of such types of reactive dyes. Oxidation of each of the investigated azo-dyes by electro-generated Fenton's reagent up to complete decolorization and approximately 90-95% mineralization was achieved. Moreover, the optimized electro-Fenton's oxidation was successfully applied for complete decolorization and approximately 85-90% mineralization of both azo-dyes in real industrial wastewater samples collected from textile dyeing house at El-Mahalla El-Kobra, Egypt. PMID:19926217

  17. Extracellular guanosine regulates extracellular adenosine levels

    PubMed Central

    Cheng, Dongmei; Jackson, Travis C.; Verrier, Jonathan D.; Gillespie, Delbert G.

    2013-01-01

    The aim of this investigation was to test the hypothesis that extracellular guanosine regulates extracellular adenosine levels. Rat preglomerular vascular smooth muscle cells were incubated with adenosine, guanosine, or both. Guanosine (30 μmol/l) per se had little effect on extracellular adenosine levels. Extracellular adenosine levels 1 h after addition of adenosine (3 μmol/l) were 0.125 ± 0.020 μmol/l, indicating rapid disposition of extracellular adenosine. Extracellular adenosine levels 1 h after addition of adenosine (3 μmol/l) plus guanosine (30 μmol/l) were 1.173 ± 0.061 μmol/l, indicating slow disposition of extracellular adenosine. Cell injury increased extracellular levels of endogenous adenosine and guanosine, and the effects of cell injury on endogenous extracellular adenosine were modulated by altering the levels of endogenous extracellular guanosine with exogenous purine nucleoside phosphorylase (converts guanosine to guanine) or 8-aminoguanosine (inhibits purine nucleoside phosphorylase). Extracellular guanosine also slowed the disposition of extracellular adenosine in rat preglomerular vascular endothelial cells, mesangial cells, cardiac fibroblasts, and kidney epithelial cells and in human aortic and coronary artery vascular smooth muscle cells and coronary artery endothelial cells. The effects of guanosine on adenosine levels were not mimicked or attenuated by 5-iodotubericidin (adenosine kinase inhibitor), erythro-9-(2-hydroxy-3-nonyl)-adenine (adenosine deaminase inhibitor), 5-aminoimidazole-4-carboxamide (guanine deaminase inhibitor), aristeromycin (S-adenosylhomocysteine hydrolase inhibitor), low sodium (inhibits concentrative nucleoside transporters), S-(4-nitrobenzyl)−6-thioinosine [inhibits equilibrative nucleoside transporter (ENT) type 1], zidovudine (inhibits ENT type 2), or acadesine (known modulator of adenosine levels). Guanosine also increases extracellular inosine, uridine, thymidine, and cytidine, yet decreases

  18. High osmotic pressure increases reactive oxygen species generation in rabbit corneal epithelial cells by endoplasmic reticulum

    PubMed Central

    Wang, Peng; Sheng, Minjie; Li, Bing; Jiang, Yaping; Chen, Yihui

    2016-01-01

    Tear high osmotic pressure (HOP) has been recognized as the core mechanism underlying ocular surface inflammation, injury and symptoms and is closely associated with many ocular surface diseases, especially dry eye. The endoplasmic reticulum (ER) is a multi-functional organelle responsible for protein synthesis, folding and transport, biological synthesis of lipids, vesicle transport and intracellular calcium storage. Accumulation of unfolded proteins and imbalance of calcium ion in the ER would induce ER stress and protective unfolded protein response (UPR). Many studies have demonstrated that ER stress can induce cell apoptosis. However, the association between tear HOP and ER stress has not been studied systematically. In the present study, rabbit corneal epithelial cells were treated with HOP and results showed that the production of reactive oxygen species increased markedly, which further activated the ER signaling pathway and ultimately induced cell apoptosis. These findings shed new lights on the pathogenesis and clinical treatment of dry eye and other ocular surface diseases. PMID:27158374

  19. Influence of ionic liquid and ionic salt on protein against the reactive species generated using dielectric barrier discharge plasma

    PubMed Central

    Attri, Pankaj; Sarinont, Thapanut; Kim, Minsup; Amano, Takaaki; Koga, Kazunori; Cho, Art E.; Ha Choi, Eun; Shiratani, Masaharu

    2015-01-01

    The presence of salts in biological solution can affect the activity of the reactive species (RS) generated by plasma, and so they can also have an influence on the plasma-induced sterilization. In this work, we assess the influence that diethylammonium dihydrogen phosphate (DEAP), an ionic liquid (IL), and sodium chloride (NaCl), an ionic salt (IS), have on the structural changes in hemoglobin (Hb) in the presence of RS generated using dielectric barrier discharge (DBD) plasma in the presence of various gases [O2, N2, Ar, He, NO (10%) + N2 and Air]. We carry out fluorescence spectroscopy to verify the generation of •OH with or without the presence of DEAP IL and IS, and we use electron spin resonance (ESR) to check the generation of H• and •OH. In addition, we verified the structural changes in the Hb structure after treatment with DBD in presence and absence of IL and IS. We then assessed the structural stability of the Hb in the presence of IL and IS by using molecular dynamic (MD) simulations. Our results indicate that the IL has a strong effect on the conservation of the Hb structure relative to that of IS against RS generated by plasma. PMID:26656857

  20. Influence of ionic liquid and ionic salt on protein against the reactive species generated using dielectric barrier discharge plasma

    NASA Astrophysics Data System (ADS)

    Attri, Pankaj; Sarinont, Thapanut; Kim, Minsup; Amano, Takaaki; Koga, Kazunori; Cho, Art E.; Ha Choi, Eun; Shiratani, Masaharu

    2015-12-01

    The presence of salts in biological solution can affect the activity of the reactive species (RS) generated by plasma, and so they can also have an influence on the plasma-induced sterilization. In this work, we assess the influence that diethylammonium dihydrogen phosphate (DEAP), an ionic liquid (IL), and sodium chloride (NaCl), an ionic salt (IS), have on the structural changes in hemoglobin (Hb) in the presence of RS generated using dielectric barrier discharge (DBD) plasma in the presence of various gases [O2, N2, Ar, He, NO (10%) + N2 and Air]. We carry out fluorescence spectroscopy to verify the generation of •OH with or without the presence of DEAP IL and IS, and we use electron spin resonance (ESR) to check the generation of H• and •OH. In addition, we verified the structural changes in the Hb structure after treatment with DBD in presence and absence of IL and IS. We then assessed the structural stability of the Hb in the presence of IL and IS by using molecular dynamic (MD) simulations. Our results indicate that the IL has a strong effect on the conservation of the Hb structure relative to that of IS against RS generated by plasma.

  1. Effect of plasma jet diameter on the efficiency of reactive oxygen and nitrogen species generation in water

    NASA Astrophysics Data System (ADS)

    Oh, Jun-Seok; Kakuta, Maito; Furuta, Hiroshi; Akatsuka, Hiroshi; Hatta, Akimitsu

    2016-06-01

    The plasma jet generation of reactive oxygen and nitrogen species (RONS) in solution is important in biology, medicine, and disinfection. Studies using a wide variety of plasma jet devices have been carried out for this purpose, making it difficult to compare the performance between devices. In this study, we compared the efficiency of RONS generation in deionized (DI) water between 3.7-mm- and 800-µm-sized helium (He) plasma jets (hereafter mm-jet and µm-jet, respectively) at different treatment distances and times. The efficiency of RONS generation was determined by considering the total amount of RONS generated in DI water with respect to the input energy and gas consumption. We found that the mm-jet generated 20% more RONS in the DI water than the µm-jet at the optimized distance. However, when the input power and He gas consumption were taken into account, we discovered that the µm-jet was 5 times more efficient in generating RONS in the DI water. Under the parameters investigated in this study, the concentration of RONS continued to increase as a function of treatment time (up to 30 min). However treatment distance had a marked effect on the efficiency of RONS generation: treatment distances of 25 and 30 mm were optimal for the mm-jet and µm-jet, respectively. Our method of comparing the efficiency of RONS generation in solution between plasma jets could be used as a reference protocol for the development of efficient plasma jet sources for use in medicine, biology, and agriculture.

  2. Mechanisms of rapid reactive oxygen species generation in response to cytosolic Ca2+ or Zn2+ loads in cortical neurons.

    PubMed

    Clausen, Aaron; McClanahan, Taylor; Ji, Sung G; Weiss, John H

    2013-01-01

    Excessive "excitotoxic" accumulation of Ca(2+) and Zn(2+) within neurons contributes to neurodegeneration in pathological conditions including ischemia. Putative early targets of these ions, both of which are linked to increased reactive oxygen species (ROS) generation, are mitochondria and the cytosolic enzyme, NADPH oxidase (NOX). The present study uses primary cortical neuronal cultures to examine respective contributions of mitochondria and NOX to ROS generation in response to Ca(2+) or Zn(2+) loading. Induction of rapid cytosolic accumulation of either Ca(2+) (via NMDA exposure) or Zn(2+) (via Zn(2+)/Pyrithione exposure in 0 Ca(2+)) caused sharp cytosolic rises in these ions, as well as a strong and rapid increase in ROS generation. Inhibition of NOX activation significantly reduced the Ca(2+)-induced ROS production with little effect on the Zn(2+)- triggered ROS generation. Conversely, dissipation of the mitochondrial electrochemical gradient increased the cytosolic Ca(2+) or Zn(2+) rises caused by these exposures, consistent with inhibition of mitochondrial uptake of these ions. However, such disruption of mitochondrial function markedly suppressed the Zn(2+)-triggered ROS, while partially attenuating the Ca(2+)-triggered ROS. Furthermore, block of the mitochondrial Ca(2+) uniporter (MCU), through which Zn(2+) as well as Ca(2+) can enter the mitochondrial matrix, substantially diminished Zn(2+) triggered ROS production, suggesting that the ROS generation occurs specifically in response to Zn(2+) entry into mitochondria. Finally, in the presence of the sulfhydryl-oxidizing agent 2,2'-dithiodipyridine, which impairs Zn(2+) binding to cytosolic metalloproteins, far lower Zn(2+) exposures were able to induce mitochondrial Zn(2+) uptake and consequent ROS generation. Thus, whereas rapid acute accumulation of Zn(2+) and Ca(2+) each can trigger injurious ROS generation, Zn(2+) entry into mitochondria via the MCU may do so with particular potency. This may be of

  3. Generation of reactive oxygen species (ROS) is a key factor for stimulation of macrophage proliferation by ceramide 1-phosphate

    SciTech Connect

    Arana, Lide; Gangoiti, Patricia; Ouro, Alberto; Rivera, Io-Guane; Ordonez, Marta; Trueba, Miguel; Lankalapalli, Ravi S.; Bittman, Robert; Gomez-Munoz, Antonio

    2012-02-15

    We previously demonstrated that ceramide 1-phosphate (C1P) is mitogenic for fibroblasts and macrophages. However, the mechanisms involved in this action were only partially described. Here, we demonstrate that C1P stimulates reactive oxygen species (ROS) formation in primary bone marrow-derived macrophages, and that ROS are required for the mitogenic effect of C1P. ROS production was dependent upon prior activation of NADPH oxidase by C1P, which was determined by measuring phosphorylation of the p40phox subunit and translocation of p47phox from the cytosol to the plasma membrane. In addition, C1P activated cytosolic calcium-dependent phospholipase A{sub 2} and protein kinase C-{alpha}, and NADPH oxidase activation was blocked by selective inhibitors of these enzymes. These inhibitors, and inhibitors of ROS production, blocked the mitogenic effect of C1P. By using BHNB-C1P (a photolabile caged-C1P analog), we demonstrate that all of these C1P actions are caused by intracellular C1P. It can be concluded that the enzyme responsible for C1P-stimulated ROS generation in bone marrow-derived macrophages is NADPH oxidase, and that this enzyme is downstream of PKC-{alpha} and cPLA{sub 2}-{alpha} in this pathway. -- Highlights: Black-Right-Pointing-Pointer Ceramide 1-phosphate (C1P) stimulates reactive oxygen species (ROS) formation. Black-Right-Pointing-Pointer The enzyme responsible for ROS generation by C1P in macrophages is NADPH oxidase. Black-Right-Pointing-Pointer NADPH oxidase lies downstream of cPLA{sub 2}-{alpha} and PKC-{alpha} in this pathway. Black-Right-Pointing-Pointer ROS generation is essential for the stimulation of macrophage proliferation by C1P.

  4. Phenethyl isothiocyanate inhibits growth of human chronic myeloid leukemia K562 cells via reactive oxygen species generation and caspases.

    PubMed

    Wang, Yating; Wei, Sixi; Wang, Jishi; Fang, Qin; Chai, Qixiang

    2014-07-01

    Phenethyl isothiocyanate (PEITC), a potential cancer chemopreventive constituent of cruciferous vegetables, including watercress, has been reported to inhibit cancer cell growth by arresting the cell cycle and inducing apoptosis in various human cancer cell models. However, the role of PEITC in the inhibition of human chronic myeloid leukemia (CML) K562 cell growth and its underlying mechanisms have yet to be elucidated. In the present study, PEITC was found to induce cell death through the induction of reactive oxygen species (ROS) stress and oxidative damage. Heme oxygenase‑1 (HO‑1), which participates in the development of numerous tumors and the sensitivity of these tumors to chemotherapeutic drugs, plays a protective role by modulating oxidative injury. Therefore, the present study assessed the inhibitory effect of PEITC on K562 cells and whether HO‑1 facilitated cell apoptosis and ROS generation. PEITC was found to suppress cell growth and cause apoptosis by promoting Fas and Fas ligand expression, increasing ROS generation and by the successive release of cytochrome c as well as the activation of caspase‑9 and caspase‑3. PEITC was also combined with the HO‑1 inhibitor zinc protoporphyrin IX and the inducer hemin to assess whether HO‑1 determines cell survival and ROS generation. The results of the present study suggest that PEITC may be a potential anti‑tumor compound for CML therapy, and that HO‑1 has a critical function in PEITC‑induced apoptosis and ROS generation. PMID:24788892

  5. Energy conversion, redox catalysis and generation of reactive oxygen species by respiratory complex I.

    PubMed

    Hirst, Judy; Roessler, Maxie M

    2016-07-01

    Complex I (NADH:ubiquinone oxidoreductase) is critical for respiration in mammalian mitochondria. It oxidizes NADH produced by the Krebs' tricarboxylic acid cycle and β-oxidation of fatty acids, reduces ubiquinone, and transports protons to contribute to the proton-motive force across the inner membrane. Complex I is also a significant contributor to cellular oxidative stress. In complex I, NADH oxidation by a flavin mononucleotide, followed by intramolecular electron transfer along a chain of iron-sulfur clusters, delivers electrons and energy to bound ubiquinone. Either at cluster N2 (the terminal cluster in the chain) or upon the binding/reduction/dissociation of ubiquinone/ubiquinol, energy from the redox process is captured to initiate long-range energy transfer through the complex and drive proton translocation. This review focuses on current knowledge of how the redox reaction and proton transfer are coupled, with particular emphasis on the formation and role of semiquinone intermediates in both energy transduction and reactive oxygen species production. This article is part of a Special Issue entitled Respiratory complex I, edited by Volker Zickermann and Ulrich Brandt. PMID:26721206

  6. Diminished Macrophage Apoptosis and Reactive Oxygen Species Generation after Phorbol Ester Stimulation in Crohn's Disease

    PubMed Central

    Palmer, Christine D.; Rahman, Farooq Z.; Sewell, Gavin W.; Ahmed, Afshan; Ashcroft, Margaret; Bloom, Stuart L.; Segal, Anthony W.; Smith, Andrew M.

    2009-01-01

    Background Crohn's Disease (CD) is a chronic relapsing disorder characterized by granulomatous inflammation of the gastrointestinal tract. Although its pathogenesis is complex, we have recently shown that CD patients have a systemic defect in macrophage function, which results in the defective clearance of bacteria from inflammatory sites. Methodology/Principal Findings Here we have identified a number of additional macrophage defects in CD following diacylglycerol (DAG) homolog phorbol-12-myristate-13-acetate (PMA) activation. We provide evidence for decreased DNA fragmentation, reduced mitochondrial membrane depolarization, impaired reactive oxygen species production, diminished cytochrome c release and increased IL-6 production compared to healthy subjects after PMA exposure. The observed macrophage defects in CD were stimulus-specific, as normal responses were observed following p53 activation and endoplasmic reticulum stress. Conclusion These findings add to a growing body of evidence highlighting disordered macrophage function in CD and, given their pivotal role in orchestrating inflammatory responses, defective apoptosis could potentially contribute to the pathogenesis of CD. PMID:19907654

  7. Ligation of Glycophorin A Generates Reactive Oxygen Species Leading to Decreased Red Blood Cell Function

    PubMed Central

    Khoory, Joseph; Estanislau, Jessica; Elkhal, Abdallah; Lazaar, Asmae; Melhorn, Mark I.; Brodsky, Abigail; Illigens, Ben; Hamachi, Itaru; Kurishita, Yasutaka; Ivanov, Alexander R.; Shevkoplyas, Sergey; Shapiro, Nathan I.; Ghiran, Ionita C.

    2016-01-01

    Acute, inflammatory conditions associated with dysregulated complement activation are characterized by significant increases in blood concentration of reactive oxygen species (ROS) and ATP. The mechanisms by which these molecules arise are not fully understood. In this study, using luminometric- and fluorescence-based methods, we show that ligation of glycophorin A (GPA) on human red blood cells (RBCs) results in a 2.1-fold, NADPH-oxidase-dependent increase in intracellular ROS that, in turn, trigger multiple downstream cascades leading to caspase-3 activation, ATP release, and increased band 3 phosphorylation. Functionally, using 2D microchannels to assess membrane deformability, GPS-ligated RBCs travel 33% slower than control RBCs, and lipid mobility was hindered by 10% using fluorescence recovery after photobleaching (FRAP). These outcomes were preventable by pretreating RBCs with cell-permeable ROS scavenger glutathione monoethyl ester (GSH-ME). Our results obtained in vitro using anti-GPA antibodies were validated using complement-altered RBCs isolated from control and septic patients. Our results suggest that during inflammatory conditions, circulating RBCs significantly contribute to capillary flow dysfunctions, and constitute an important but overlooked source of intravascular ROS and ATP, both critical mediators responsible for endothelial cell activation, microcirculation impairment, platelet activation, as well as long-term dysregulated adaptive and innate immune responses. PMID:26784696

  8. Reactive-power compensation of coal mining excavators by using a new-generation STATCOM

    SciTech Connect

    Bilgin, H.F.; Ermis, M.; Kose, K.N.; Cadirci, I.; Acik, A.; Demirci, T.; Terciyanli, A.; Kocak, C.; Yorukoglu, M.

    2007-01-15

    This paper deals with the development and implementation of a current-source-converter-based static synchronous compensator (CSC-STATCOM) applied to the volt-ampere-reactive (VAR) compensation problem of coal mining excavators. It is composed of a +/- 750-kVAR full-bridge CSC with selective harmonic elimination, a low-pass input filter tuned to 200 Hz, and a Delta/Y-connected coupling transformer for connection to medium-voltage load bus. Each power semiconductor switch is composed of an asymmetrical integrated gate commutated thyristor (IGCT) connected in series with a reverse-blocking diode and switched at 500 Hz to eliminate 5th, 7th, 11th, and 13th current harmonics produced by the CSC. Operating principles, power stage, design of dc link, and input filter are also described in this paper. It has been verified by field tests that the developed STATCOM follows rapid fluctuations in nearly symmetrical lagging and leading VAR consumption of electric excavators, resulting in nearly unity power factor on monthly basis, and the harmonic current spectra in the lines of CSC-STATCOM at the point of common coupling comply with the IEEE Standard 519-1992.

  9. Colloidal gold nanorings for improved photodynamic therapy through field-enhanced generation of reactive oxygen species

    NASA Astrophysics Data System (ADS)

    Hu, Yue; Yang, Yamin; Wang, Hongjun; Du, Henry

    2013-02-01

    Au nanostructures that exhibit strong localized surface plasmon resonance (SPR) have excellent potential for photo-medicine, among a host of other applications. Here, we report the synthesis and use of colloidal gold nanorings (GNRs) with potential for enhanced photodynamic therapy of cancer. The GNRs were fabricated via galvanic replacement reaction of sacrificial Co nanoparticles in gold salt solution with low molecular weight (Mw = 2,500) poly(vinylpyrrolidone) (PVP) as a stabilizing agent. The size and the opening of the GNRs were controlled by the size of the starting Co particles and the concentration of the gold salt. UV-Vis absorption measurements indicated the tunability of the SPR of the GNRs from 560 nm to 780 nm. MTT assay showed that GNRs were non-toxic and biocompatible when incubated with breast cancer cells as well as the healthy counterpart cells. GNRs conjugated with 5-aminolevulinic acid (5-ALA) photosensitizer precursor led to elevated formation of reactive oxygen species and improved efficacy of photodynamic therapy of breast cancer cells under light irradiation compared to 5-ALA alone. These results can be attributed to significantly enhance localized electromagnetic field of the GNRs.

  10. Advanced glycation end products delay corneal epithelial wound healing through reactive oxygen species generation.

    PubMed

    Shi, Long; Chen, Hongmei; Yu, Xiaoming; Wu, Xinyi

    2013-11-01

    Delayed healing of corneal epithelial wounds is a serious complication in diabetes. Advanced glycation end products (AGEs) are intimately associated with the diabetic complications and are deleterious to the wound healing process. However, the effect of AGEs on corneal epithelial wound healing has not yet been evaluated. In the present study, we investigated the effect of AGE-modified bovine serum albumin (BSA) on corneal epithelial wound healing and its underlying mechanisms. Our data showed that AGE-BSA significantly increased the generation of intracellular ROS in telomerase-immortalized human corneal epithelial cells. However, the generation of intracellular ROS was completely inhibited by antioxidant N-acetylcysteine (NAC), anti-receptor of AGEs (RAGE) antibodies, or the inhibitor of NADPH oxidase. Moreover, AGE-BSA increased NADPH oxidase activity and protein expression of NADPH oxidase subunits, p22phox and Nox4, but anti-RAGE antibodies eliminated these effects. Furthermore, prevention of intracellular ROS generation using NAC or anti-RAGE antibodies rescued AGE-BSA-delayed epithelial wound healing in porcine corneal organ culture. In conclusion, our results demonstrated that AGE-BSA impaired corneal epithelial wound healing ex vivo. AGE-BSA increased intracellular ROS generation through NADPH oxidase activation, which accounted for the delayed corneal epithelial wound healing. These results may provide better insights for understanding the mechanism of delayed healing of corneal epithelial wounds in diabetes. PMID:23955437

  11. Lysosomal membrane permeabilization: Carbon nanohorn-induced reactive oxygen species generation and toxicity by this neglected mechanism

    SciTech Connect

    Yang, Mei; Zhang, Minfang; Tahara, Yoshio; Chechetka, Svetlana; Miyako, Eijiro; Iijima, Sumio; Yudasaka, Masako

    2014-10-01

    Understanding the molecular mechanisms responsible for the cytotoxic effects of carbon nanomaterials is important for their future biomedical applications. Carbon nanotubular materials induce the generation of reactive oxygen species (ROS), which causes cell death; however, the exact details of this process are still unclear. Here, we identify a mechanism of ROS generation that is involved in the apoptosis of RAW264.7 macrophages caused by excess uptake of carbon nanohorns (CNHs), a typical type of carbon nanotubule. CNH accumulated in the lysosomes, where they induced lysosomal membrane permeabilization (LMP) and the subsequent release of lysosomal proteases, such as cathepsins, which in turn caused mitochondrial dysfunction and triggered the generation of ROS in the mitochondria. The nicotinamide adenine dinucleotide phosphate oxidase was not directly involved in CNH-related ROS production, and the ROS generation cannot be regulated by mitochondrial electron transport chain. ROS fed back to amplify the mitochondrial dysfunction, leading to the subsequent activation of caspases and cell apoptosis. Carbon nanotubules commonly accumulate in the lysosomes after internalization in cells; however, lysosomal dysfunction has not attracted much attention in toxicity studies of these materials. These results suggest that LMP, a neglected mechanism, may be the primary reason for carbon nanotubule toxicity. - Highlights: • We clarify an apoptotic mechanism of RAW264.7 cells caused by carbon nanohorns. • In the meantime, the mechanism of CNH-induced ROS generation is identified. • LMP is the initial factor of CNH-induced ROS generation and cell death. • Cathepsins work as mediators that connect LMP and mitochondrial dysfunction.

  12. Hierarchical Testing with Automated Document Generation for Amanzi, ASCEM's Subsurface Flow and Reactive Transport Simulator

    NASA Astrophysics Data System (ADS)

    Moulton, J. D.; Steefel, C. I.; Yabusaki, S.; Castleton, K.; Scheibe, T. D.; Keating, E. H.; Freedman, V. L.

    2013-12-01

    The Advanced Simulation Capabililty for Environmental Management (ASCEM) program is developing an approach and open-source tool suite for standardized risk and performance assessments at legacy nuclear waste sites. These assessments use a graded and iterative approach, beginning with simplified highly abstracted models, and adding geometric and geologic complexity as understanding is gained. To build confidence in this assessment capability, extensive testing of the underlying tools is needed. Since the tools themselves, such as the subsurface flow and reactive-transport simulator, Amanzi, are under active development, testing must be both hierarchical and highly automated. In this presentation we show how we have met these requirements, by leveraging the python-based open-source documentation system called Sphinx with several other open-source tools. Sphinx builds on the reStructured text tool docutils, with important extensions that include high-quality formatting of equations, and integrated plotting through matplotlib. This allows the documentation, as well as the input files for tests, benchmark and tutorial problems, to be maintained with the source code under a version control system. In addition, it enables developers to build documentation in several different formats (e.g., html and pdf) from a single source. We will highlight these features, and discuss important benefits of this approach for Amanzi. In addition, we'll show that some of ASCEM's other tools, such as the sampling provided by the Uncertainty Quantification toolset, are naturally leveraged to enable more comprehensive testing. Finally, we will highlight the integration of this hiearchical testing and documentation framework with our build system and tools (CMake, CTest, and CDash).

  13. Generation, Characterization, and Tunable Reactivity of Organometallic Fragments Bound to a Protein Ligand.

    PubMed

    Key, Hanna M; Clark, Douglas S; Hartwig, John F

    2015-07-01

    Organotransition metal complexes catalyze important synthetic transformations, and the development of these systems has rested on the detailed understanding of the structures and elementary reactions of discrete organometallic complexes bound to organic ligands. One strategy for the creation of new organometallic systems is to exploit the intricate and highly structured ligands found in natural metalloproteins. We report the preparation and characterization of discrete rhodium and iridium fragments bound site-specifically in a κ(2)-fashion to the protein carbonic anhydrase as a ligand. The reactions of apo human carbonic anhydrase with [Rh(nbd)2]BF4 or [M(CO)2(acac)] (M=Rh, Ir) form proteins containing Rh or Ir with organometallic ligands. A colorimetric assay was developed to quantify rapidly the metal occupancy at the native metal-binding site, and (15)N-(1)H NMR spectroscopy was used to establish the amino acids to which the metal is bound. IR spectroscopy and EXAFS revealed the presence and number of carbonyl ligands and the number total ligands, while UV-vis spectroscopy provided a signature to readily identify species that had been fully characterized. Exploiting these methods, we observed fundamental stoichiometric reactions of the artificial organometallic site of this protein, including reactions that simultaneously form and cleave metal-carbon bonds. The preparation and reactivity of these artificial organometallic proteins demonstrate the potential to study a new genre of organometallic complexes for which the rates and outcomes of organometallic reactions can be controlled by genetic manipulation of the protein scaffold. PMID:26020584

  14. Generation of reactive astrocytes from NG2 cells is regulated by sonic hedgehog.

    PubMed

    Honsa, Pavel; Valny, Martin; Kriska, Jan; Matuskova, Hana; Harantova, Lenka; Kirdajova, Denisa; Valihrach, Lukas; Androvic, Peter; Kubista, Mikael; Anderova, Miroslava

    2016-09-01

    NG2 cells, a fourth glial cell type in the adult mammalian central nervous system, produce oligodendrocytes in the healthy nervous tissue, and display wide differentiation potential under pathological conditions, where they could give rise to reactive astrocytes. The factors that control the differentiation of NG2 cells after focal cerebral ischemia (FCI) are largely unknown. Here, we used transgenic Cspg4-cre/Esr1/ROSA26Sortm14(CAG-tdTomato) mice, in which tamoxifen administration triggers the expression of red fluorescent protein (tomato) specifically in NG2 cells and cells derived therefrom. Differentiation potential (in vitro and in vivo) of tomato-positive NG2 cells from control or postischemic brains was determined using the immunohistochemistry, single cell RT-qPCR and patch-clamp method. The ischemic injury was induced by middle cerebral artery occlusion, a model of FCI. Using genetic fate-mapping method, we identified sonic hedgehog (Shh) as an important factor that influences differentiation of NG2 cells into astrocytes in vitro. We also manipulated Shh signaling in the adult mouse brain after FCI. Shh signaling activation significantly increased the number of astrocytes derived from NG2 cells in the glial scar around the ischemic lesion, while Shh signaling inhibition caused the opposite effect. Since Shh signaling modifications did not change the proliferation rate of NG2 cells, we can conclude that Shh has a direct influence on the differentiation of NG2 cells and therefore, on the formation and composition of a glial scar, which consequently affects the degree of the brain damage. GLIA 2016;64:1518-1531. PMID:27340757

  15. Reactive Oxygen Species Generation by Lunar Simulants in Simulated Lung Fluid

    NASA Astrophysics Data System (ADS)

    Schoonen, M. A.; Kaur, J.; Rickman, D.

    2015-12-01

    The current interest in human exploration of the Moon and other airless planetary bodies has rekindled research into the harmful effects of Lunar dust on human health. Our team has evaluated the spontaneous formation of Reactive Oxygen Species (ROS; hydroxyl radicals, superoxide, and hydrogen peroxide) of a suite of lunar simulants when dispersed in deionized water. Of these species, hydroxyl radical reacts almost immediately with any biomolecule leading to oxidative damage. Sustained production of OH radical as a result of mineral exposure can initiate or enhance disease. The results in deionized water indicate that mechanical stress and the absence of molecular oxygen and water, important environmental characteristics of the lunar environment, can lead to enhanced production of ROS in general. On the basis of the results with deionized water, a few of the simulants were selected for additional studies to evaluate the formation of hydrogen peroxide, a precursor of hydroxyl radical in Simulated Lung Fluid. These simulants dispersed in deionized water typically produce a maximum in H2O2 within 10 to 40 minutes. However, experiments in SLF show a slow steady increase in H2O2 concentration that has been documented to continue for as long as 7 hours. Control experiments with one simulant demonstrate that the rise in H2O2 depends on the availability of dissolved O2. We speculate that this continuous rise in oxygenated SLF might be a result of metal ion-mediated oxidation of organic components, such as glycine in SLF. Ion-mediated oxidation essentially allows dissolved molecular oxygen to react with dissolved organic compounds by forming a metal-organic complex. Results of separate experiments with dissolved Fe, Ni, and Cu and speciation calculations support this notion.

  16. Testosterone improves erectile function through inhibition of reactive oxygen species generation in castrated rats

    PubMed Central

    Li, Rui; Meng, Xianghu; Zhang, Yan; Wang, Tao; Yang, Jun; Niu, Yonghua; Cui, Kai; Wang, Shaogang

    2016-01-01

    Testosterone is overwhelmingly important in regulating erectile physiology. However, the associated molecular mechanisms are poorly understood. The purpose of this study was to explore the effects and mechanisms of testosterone in erectile dysfunction (ED) in castrated rats. Forty male Sprague-Dawley rats were randomized to four groups (control, sham-operated, castration and castration-with-testosterone-replacement). Reactive oxygen species (ROS) production was measured by dihydroethidium (DHE) staining. Erectile function was assessed by the recording of intracavernous pressure (ICP) and mean arterial blood pressure (MAP). Protein expression levels were examined by western blotting. We found that castration reduced erectile function and that testosterone restored it. Nitric oxide synthase (NOS) activity was decrease in the castrated rats, and testosterone administration attenuated this decrease (each p < 0.05). The testosterone, dihydrotestosterone, cyclic guanosine monophosphate (cGMP) and cyclic adenosine monophosphate (cAMP) concentrations were lower in the castrated rats, and testosterone restored these levels (each p < 0.05). Furthermore, the cyclooxygenase-2 (COX-2) and prostacyclin synthase (PTGIS) expression levels and phospho-endothelial nitric oxide synthase (p-eNOS, Ser1177)/endothelial nitric oxide synthase (eNOS) ratio were reduced in the castrated rats compared with the controls (each p < 0.05). In addition, the p40phox and p67phox expression levels were increased in the castrated rats, and testosterone reversed these changes (each p < 0.05). Overall, our results demonstrate that testosterone ameliorates ED after castration by reducing ROS production and increasing the activity of the eNOS/cGMP and COX-2/PTGIS/cAMP signaling pathways. PMID:27168996

  17. Nanopore formation process in artificial cell membrane induced by plasma-generated reactive oxygen species.

    PubMed

    Tero, Ryugo; Yamashita, Ryuma; Hashizume, Hiroshi; Suda, Yoshiyuki; Takikawa, Hirofumi; Hori, Masaru; Ito, Masafumi

    2016-09-01

    We investigated morphological change of an artificial lipid bilayer membrane induced by oxygen radicals which were generated by non-equilibrium atmospheric pressure plasma. Neutral oxygen species, O((3)Pj) and O2((1)Δg), were irradiated of a supported lipid bilayer existing under a buffer solution at various conditions of dose time and distances, at which the dose amounts of the oxygen species were calculated quantitatively. Observation using an atomic force microscope and a fluorescence microscope revealed that dose of the neutral oxygen species generated nanopores with the diameter of 10-50 nm in a phospholipid bilayer, and finally destructed the bilayer structure. We found that protrusions appeared on the lipid bilayer surface prior to the formation of nanopores, and we attributed the protrusions to the precursor of the nanopores. We propose a mechanism of the pore formation induced by lipid oxidation on the basis of previous experimental and theoretical studies. PMID:27216034

  18. Newly synthesized bis-benzimidazole compound 8 induces apoptosis, autophagy and reactive oxygen species generation in HeLa cells.

    PubMed

    Chu, Naying; Yao, Guodong; Liu, Yuan; Cheng, Maosheng; Ikejima, Takashi

    2016-09-01

    Compound 8 (C8) is a newly synthesized bis-benzimidazole derivative and exerts significant anti-tumor activity in vitro. Previous studies demonstrated that C8 induced apoptosis and autophagy in human promyelocytic leukemia HL60 cells. However, cytotoxicity study on human peripheral blood mononuclear cells (hPBMC) showed that C8 exhibited less toxicity in normal cells. In this study, the molecular mechanism of C8 on human cervical carcinoma HeLa cells was investigated. The results showed that C8 inhibited the growth of HeLa cells and triggered both apoptotic and autophagic cell death. Subsequent experiment also indicated that reactive oxygen species (ROS) generation was induced in C8-treated HeLa cells. Since ROS scavenger decreased the ratio of apoptotic and autophagic cells, ROS generation contributed to C8-induced apoptosis and autophagy. Furthermore, inhibitors of apoptosis and autophagy also reduced ROS generation, respectively. Autophagy inhibition increased cell growth compared to C8-treated group and attenuated apoptotic cell death, indicating that C8-induced autophagy promoted apoptosis for cell death. However, the percentage of autophagic cells was enhanced when limiting apoptosis process. Taken together, C8 induced ROS-mediated apoptosis and autophagy in HeLa cells, autophagy promoted apoptosis but the former was antagonized by the latter. The data also gave us a new perspective on the anti-tumor effect of C8. PMID:27497983

  19. Peroxiredoxin 1 knockdown sensitizes cancer cells to reactive oxygen species-generating drugs - an alternative approach for chemotherapy.

    PubMed

    He, Tiantian; Hatem, Elie; Vernis, Laurence; Huang, Meng-Er

    2014-10-01

    Peroxiredoxins have multiple cellular functions as major antioxidants, signaling regulators and tumor suppressors. Peroxiredoxin 1 (PRX1) is the most abundant among the six isoforms of human peroxiredoxins, catalyzing the reduction of peroxides utilizing thioredoxin 1as an electron donor. PRX1 is frequently over-expressed in various cancer cells, which is thought to be associated with carcinogenesis, metastasis and resistance to radiotherapy or chemotherapy. We investigated how modulations of intracellular redox system, especially PRX1, affect cancer cell sensitivity to reactive oxygen species (ROS)-generating drugs. We observed that stable and transient Prx1 knockdown (Prx1-) significantly enhances HeLa cell sensitivity to β-lapachone (β-lap), a potential anticancer agent, and to other ROS-generating molecules. ROS accumulation played a crucial role in drug-enhanced Prx1- cell death. For β-lap, Prx1- cells sensitization is achieved through combined action of accumulation of ROS and enhancement of mitogen-activated protein kinase pathway activation. The effect of other ROS-inducing drugs on Prx1- cell survival will also be presented and discussed. Taken together, our data provide evidence that PRX1 could be an interesting anticancer target and modulation of intracellular redox states through PRX1 inhibition could be an alternative approach to enhance cancer cell sensitivity to ROS-generating drugs. PMID:26461286

  20. Neutrophil extracellular traps as a new paradigm in innate immunity: friend or foe?

    PubMed

    Cooper, Paul R; Palmer, Lisa J; Chapple, Iain L C

    2013-10-01

    The discovery of neutrophil extracellular traps in 2004 opened a fascinating new chapter in immune-mediated microbial killing. Brinkman et al. demonstrated that neutrophils, when catastrophically stimulated, undergo a novel form of programmed cell death (neutrophil extracellular trap formation) whereby they decondense their entire nuclear chromatin/DNA and release the resulting structure into the cytoplasm to mix with granule-derived antimicrobial peptides before extruding these web-like structures into the extracellular environment. The process requires the activation of the granule enzyme peptidyl arginine deiminase-4, the formation of reactive oxygen species (in particular hypochlorous acid), the neutrophil microtubular system and the actin cytoskeleton. Recent work by Yousefi et al. demonstrated that exposure to different agents for shorter stimulation periods resulted in neutrophil extracellular trap release from viable granulocytes, and that such neutrophil extracellular traps comprised mitochondrial DNA rather than nuclear DNA and were also capable of microbial entrapment and destruction. Deficiency in NADPH-oxidase production (as found in patients with chronic granulomatous disease) results in an inability to produce neutrophil extracellular traps and, along with their failure to produce antimicrobial reactive oxygen species, these patients suffer from severe, and sometimes life-threatening, infections. However, conversely the release of nuclear chromatin into tissues is also potentially autoimmunogenic and is now associated with the generation of anti-citrullinated protein antibodies in seropositive rheumatoid arthritis. Other neutrophil-derived nuclear and cytoplasmic contents are also pathogenic, either through direct effects on tissues or via autoimmune processes (e.g. autoimmune vasculitis). In this review, we discuss the plant origins of a highly conserved innate immune method of microbial killing, the history and biology of neutrophil extracellular

  1. Reactive molecular dynamics of network polymers: Generation, characterization and mechanical properties

    NASA Astrophysics Data System (ADS)

    Shankar, Chandrashekar

    The goal of this research was to gain a fundamental understanding of the properties of networks created by the ring opening metathesis polymerization (ROMP) of dicyclopentadiene (DCPD) used in self-healing materials. To this end we used molecular simulation methods to generate realistic structures of DCPD networks, characterize their structures, and determine their mechanical properties. Density functional theory (DFT) calculations, complemented by structural information derived from molecular dynamics simulations were used to reconstruct experimental Raman spectra and differential scanning calorimetry (DSC) data. We performed coarse-grained simulations comparing networks generated via the ROMP reaction process and compared them to those generated via a RANDOM process, which led to the fundamental realization that the polymer topology has a unique influence on the network properties. We carried out fully atomistic simulations of DCPD using a novel algorithm for recreating ROMP reactions of DCPD molecules. Mechanical properties derived from these atomistic networks are in excellent agreement with those obtained from coarse-grained simulations in which interactions between nodes are subject to angular constraints. This comparison provides self-consistent validation of our simulation results and helps to identify the level of detail necessary for the coarse-grained interaction model. Simulations suggest networks can classified into three stages: fluid-like, rubber-like or glass-like delineated by two thresholds in degree of reaction alpha: The onset of finite magnitudes for the Young's modulus, alphaY, and the departure of the Poisson ration from 0.5, alphaP. In each stage the polymer exhibits a different predominant mechanical response to deformation. At low alpha < alphaY it flows. At alpha Y < alpha < alphaP the response is entropic with no change in internal energy. At alpha > alphaP the response is enthalpic change in internal energy. We developed graph theory

  2. Nitric oxide reactivity of [2Fe-2S] clusters leading to H2S generation.

    PubMed

    Tran, Camly T; Williard, Paul G; Kim, Eunsuk

    2014-08-27

    The crosstalk between two biologically important signaling molecules, nitric oxide (NO) and hydrogen sulfide (H2S), proceeds via elusive mechanism(s). Herein we report the formation of H2S by the action of NO on synthetic [2Fe-2S] clusters when the reaction environment is capable of providing a formal H(•) (e(-)/H(+)). Nitrosylation of (NEt4)2[Fe2S2(SPh)4] (1) in the presence of PhSH or (t)Bu3PhOH results in the formation of (NEt4)[Fe(NO)2(SPh)2] (2) and H2S with the concomitant generation of PhSSPh or (t)Bu3PhO(•). The amount of H2S generated is dependent on the electronic environment of the [2Fe-2S] cluster as well as the type of H(•) donor. Employment of clusters with electron-donating groups or H(•) donors from thiols leads to a larger amount of H2S evolution. The 1/NO reaction in the presence of PhSH exhibits biphasic decay kinetics with no deuterium kinetic isotope effect upon PhSD substitution. However, the rates of decay increase significantly with the use of 4-MeO-PhSH or 4-Me-PhSH in place of PhSH. These results provide the first chemical evidence to suggest that [Fe-S] clusters are likely to be a site for the crosstalk between NO and H2S in biology. PMID:25113815

  3. Generation and reactivation of T-cell receptor A joining region pseudogenes in primates

    SciTech Connect

    Thiel, C.; Lanchbury, J.S.; Otting, N.

    1996-06-01

    Tandemly duplicated T-cell receptor (Tcr) AJ (J{alpha}) segments contribute significantly to TCRA chain junctional region diversity in mammals. Since only limited data exists on TCRA diversity in nonhuman primates, we examined the TCRAJ regions of 37 chimpanzee and 71 rhesus macaque TCRA cDNA clones derived from inverse polymerase chain reaction on peripheral blood mononuclear cell cDNA of healthy animals. Twenty-five different TCRAJ regions were characterized in the chimpanzee and 36 in the rhesus macaque. Each bears a close structural relationship to an equivalent human TCRAJ region. Conserved amino acid motifs are shared between all three species. There are indications that differences between nonhuman primates and humans exist in the generation of TCRAJ pseudogenes. The nucleotide and amino acid sequences of the various characterized TCRAJ of each species are reported and we compare our results to the available information on human genomic sequences. Although we provide evidence of dynamic processes modifying TCRAJ segments during primate evolution, their repertoire and primary structure appears to be relatively conserved. 21 refs., 2 figs.

  4. Effect of Structural Transformation of Nanoparticulate Zero-Valent Iron on Generation of Reactive Oxygen Species.

    PubMed

    He, Di; Ma, Jinxing; Collins, Richard N; Waite, T David

    2016-04-01

    While it has been recognized for some time that addition of nanoparticlate zerovalent iron (nZVI) to oxygen-containing water results in both corrosion of Fe(0) and oxidation of contaminants, there is limited understanding of either the relationship between transformation of nZVI and oxidant formation or the factors controlling the lifetime and extent of oxidant production. Using Fe K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy, we show that while nZVI particles are transformed to ferrihydrite then lepidocrocite in less than 2 h, oxidant generation continues for up to 10 h. The major products (Fe(II) and H2O2) of the reaction of nZVI with oxygenated water are associated, for the most part, with the surface of particles present with these surface-associated Fenton reagents inducing oxidation of a target compound (in this study, (14)C-labeled formate). Effective oxidation of formate only occurred after formation of iron oxides on the nZVI surface with the initial formation of high surface area ferrihydrite facilitating rapid and extensive adsorption of formate with colocation of this target compound and surface-associated Fe(II) and H2O2 apparently critical to formate oxidation. Ongoing formate oxidation long after nZVI is consumed combined with the relatively slow consumption of Fe(II) and H2O2 suggest that these reactants are regenerated during the nZVI-initiated heterogeneous Fenton process. PMID:26958862

  5. Picosecond Spectroscopy of Reactive Intermediates: Generation and Dynamics of Arylmethyl Ions and Radicals in Solution.

    NASA Astrophysics Data System (ADS)

    Schmidt, Jeffrey Allan

    A detailed experimental description is presented of a practical and relatively inexpensive approach for two simultaneous and independent types of picosecond spectroscopic measurements. Two data collection subsystems, (1) a picosecond pump-probe transient absorption/emission spectrometer and (2) a streak camera system for time-dependent measurements of absorption and emission, were developed as independent subsystems within an integrated system based on a single mode-locked Nd:YAG laser which concurrently supplies each subsystem with picosecond pulses. Considerations concerning electrical and optical interfacing between the two subsystems are discussed. With these two subsystems, picosecond-pulsed photolyses of diphenylmethyl chloride, diphenylmethyl bromide, triphenylmethyl chloride, triphenylmethyl bromide, and triphenylacetyl chloride in acetonitrile, methylene chloride, and cyclohexane were studied. The dependence of the yields of radicals and ions are discussed with respect to the nature of the starting compound and the solvent. Ion-pair dynamics were monitored with subsystems 1 and 2. Microscopic rate constants for the collapse of the contact ion pair (CIP), separation of the CIP, and reformation of the CIP from the separated ions were calculated. The photophysics and photochemistry of the triphenylmethyl radical generated from triphenylmethyl chloride, and triphenylacetyl chloride, and tert-butyl triphenylperacetate in solution were studied by means of a unique three-pulse picosecond transient absorption technique. The emission lifetime of the excited triphenylmethyl radical was measured as a function of solvent polarity with subsystem 2. These data were collectively used to gain an understanding of the electronically excited triphenylmethyl radical.

  6. Phloretin induces cell cycle arrest and apoptosis of human glioblastoma cells through the generation of reactive oxygen species.

    PubMed

    Liu, Yuanyuan; Fan, Chenghe; Pu, Lv; Wei, Cui; Jin, Haiqiang; Teng, Yuming; Zhao, Mingming; Yu, Albert Cheung Hoi; Jiang, Feng; Shu, Junlong; Li, Fan; Peng, Qing; Kong, Jian; Pan, Bing; Zheng, Lemin; Huang, Yining

    2016-06-01

    Phloretin, a flavonoid present in various plants, has been reported to exert anticarcinogenic effects. However, the mechanism of its chemo-preventive effect on human glioblastoma cells is not fully understood. This study aimed to investigate the molecular mechanism of phloretin and its associated chemo-preventive effect in human glioblastoma cells. The results indicate that phloretin inhibited cell proliferation by inducing cell cycle arrest at the G0-G1 phase and induced apoptosis of human glioblastoma cells. Phloretin-induced cell cycle arrest was associated with increased expression of p27 and decreased expression of cdk2, cdk4, cdk6, cyclinD and cyclinE. Moreover, the PI3K/AKT/mTOR signaling cascades were suppressed by phloretin in a dose-dependent manner. In addition, phloretin triggered the mitochondrial apoptosis pathway and generated reactive oxygen species (ROS). This was accompanied by the up-regulation of Bax, Bak and c-PARP and the down-regulation of Bcl-2. The antioxidant agents N-acetyl-L-cysteine and glutathione weakened the effect of phloretin on glioblastoma cells. In conclusion, these results demonstrate that phloretin exerts potent chemo-preventive activity in human glioblastoma cells through the generation of ROS. PMID:26983952

  7. Caudatin induces caspase-dependent apoptosis in human glioma cells with involvement of mitochondrial dysfunction and reactive oxygen species generation.

    PubMed

    Zhu, Liang-Zhen; Hou, Ya-Jun; Zhao, Ming; Yang, Ming-Feng; Fu, Xiao-Ting; Sun, Jing-Yi; Fu, Xiao-Yan; Shao, Lu-Rong; Zhang, Hui-Fang; Fan, Cun-Dong; Gao, Hong-Li; Sun, Bao-Liang

    2016-08-01

    Caudatin as one species of C-21 steroidal from Cynanchum bungei decne displays potential anticancer activity. However, the underlying mechanisms remain elusive. In the present study, the growth suppressive effect and mechanism of caudatin on human glioma U251 and U87 cells were evaluated in vitro. The results indicated that caudatin significantly inhibited U251 and U87 cell growth in both a time- and dose-dependent manner. Flow cytometry analysis revealed that caudatin-induced cell growth inhibition was achieved by induction of cell apoptosis, as convinced by the increase of Sub-G1 peak, PARP cleavage and activation of caspase-3, caspase-7 and caspase-9. Caudatin treatment also resulted in mitochondrial dysfunction which correlated with an imbalance of Bcl-2 family members. Further investigation revealed that caudatin triggered U251 cell apoptosis by inducing reactive oxygen species (ROS) generation through disturbing the redox homeostasis. Moreover, pretreatment of caspase inhibitors apparently weakens caudatin-induced cell killing, PARP cleavage and caspase activation and eventually reverses caudatin-mediated apoptosis. Importantly, caudatin significantly inhibited U251 tumour xenografts in vivo through induction of cell apoptosis involving the inhibition of cell proliferation and angiogenesis, which further validate its value in combating human glioma in vivo. Taken together, the results described above all suggest that caudatin inhibited human glioma cell growth by induction of caspase-dependent apoptosis with involvement of mitochondrial dysfunction and ROS generation. PMID:27184666

  8. Apoptosis induction of U937 human leukemia cells by diallyl trisulfide induces through generation of reactive oxygen species

    PubMed Central

    2012-01-01

    Background Diallyl trisulfide (DATS) is one of the major constituents in garlic oil and has demonstrated various pharmacological activities, including antimicrobial, antihyperlipidemic, antithrombotic, and anticancer effects. However, the mechanisms of antiproliferative activity in leukemia cells are not fully understood. In this study, the apoptotic effects of DATS were investigated in human leukemia cells. Results Results of this study indicated that treatment with DATS resulted in significantly inhibited leukemia cell growth in a concentration- and time-dependent manner by induction of apoptosis. In U937 cells, DATS-induced apoptosis was correlated with down-regulation of Bcl-2, XIAP, and cIAP-1 protein levels, cleavage of Bid proteins, activation of caspases, and collapse of mitochondrial membrane potential. The data further demonstrated that DATS increased intracellular reactive oxygen species (ROS) generation, which was attenuated by pretreatment with antioxidant N-acetyl-l-cysteine (NAC), a scavenger of ROS. In addition, administration of NAC resulted in significant inhibition of DATS-induced apoptosis by inhibiting activation of caspases. Conclusions The present study reveals that the cytotoxicity caused by DATS is mediated by generation of ROS and subsequent activation of the ROS-dependent caspase pathway in U937 leukemia cells. PMID:22578287

  9. Bcl-2 overexpression inhibits generation of intracellular reactive oxygen species and blocks adriamycin-induced apoptosis in bladder cancer cells.

    PubMed

    Kong, Chui-Ze; Zhang, Zhe

    2013-01-01

    Resistance to induction of apoptosis is a major obstacle for bladder cancer treatment. Bcl-2 is thought to be involved in anti-apoptotic signaling. In this study, we investigated the effect of Bcl-2 overexpression on apoptotic resistance and intracellular reactive oxygen species (ROS) generation in bladder cancer cells. A stable Bcl-2 overexpression cell line, BIU87-Bcl-2, was constructed from human bladder cancer cell line BIU87 by transfecting recombinant Bcl-2 [pcDNA3.1(+)-Bcl-2]. The sensitivity of transfected cells to adriamycin (ADR) was assessed by MTT assay. Apoptosis was examined by flow cytometry and acridine orange fluorescence staining. Intracellular ROS was determined using flow cytometry, and the activities of superoxide dismutase (SOD) and catalase (CAT) were also investigated by the xanthinoxidase and visible radiation methods using SOD and CAT detection kits. The susceptibility of BIU87-Bcl-2 cells to ADR treatment was significantly decreased as compared with control BIU87 cells. Enhanced expression of Bcl-2 inhibited intracellular ROS generation following ADR treatment. Moreover, the suppression of SOD and CAT activity induced by ADR treatment was blocked in the BIU87-Bcl-2 case but not in their parental cells. The overexpression of Bcl-2 renders human bladder cancer cells resistant to ADR-induced apoptosis and ROS might act as an important secondary messenger in this process. PMID:23621258

  10. Protective effects of α-tocopherol and ascorbic acid against cardol-induced cell death and reactive oxygen species generation in Staphylococcus aureus.

    PubMed

    Murata, Wakae; Tanaka, Toshio; Kubo, Isao; Fujita, Ken-ichi

    2013-06-01

    Cardol (C₁₅:₃), isolated from cashew (Anacardium occidentale L.) nut shell liquid, has been shown to exhibit bactericidal activity against various strains of Staphylococcus aureus, including methicillin-resistant strains. The maximum level of reactive oxygen species generation was detected at around the minimum bactericidal concentration of cardol, while reactive oxygen species production drastically decreased at doses above the minimum bactericidal concentration. The primary response for bactericidal activity around the bactericidal concentration was noted to primarily originate from oxidative stress such as intracellular reactive oxygen species generation. High doses of cardol (C₁₅:₃) were shown to induce leakage of K⁺ from S. aureus cells, which may be related to the decrease in reactive oxygen species. Antioxidants such as α-tocopherol and ascorbic acid restricted reactive oxygen species generation and restored cellular damage induced by the lipid. Cardol (C₁₅:₃) overdose probably disrupts the native membrane-associated function as it acts as a surfactant. The maximum antibacterial activity of cardols against S. aureus depends on their log P values (partition coefficient in octanol/water) and is related to their similarity to those of anacardic acids isolated from the same source. PMID:23670625

  11. Apogossypolone targets mitochondria and light enhances its anticancer activity by stimulating generation of singlet oxygen and reactive oxygen species

    PubMed Central

    Hu, Zhe-Yu; Wang, Jing; Cheng, Gang; Zhu, Xiao-Feng; Huang, Peng; Yang, Dajun; Zeng, Yi-Xin

    2011-01-01

    Apogossypolone (ApoG2), a novel derivative of gossypol, has been shown to be a potent inhibitor of antiapoptotic Bcl-2 family proteins and to have antitumor activity in multiple types of cancer cells. Recent reports suggest that gossypol stimulates the generation of cellular reactive oxygen species (ROS) in leukemia and colorectal carcinoma cells; however, gossypol-mediated cell death in leukemia cells was reported to be ROS-independent. This study was conducted to clarify the effect of ApoG2-induced ROS on mitochondria and cell viability, and to further evaluate its utility as a treatment for nasopharyngeal carcinoma (NPC). We tested the photocytotoxicity of ApoG2 to the poorly differentiated NPC cell line CNE-2 using the ROS-generating TL/10 illumination system. The rapid ApoG2-induced cell death was partially reversed by the antioxidant N-acetyl-L-cysteine (NAC), but the ApoG2-induced reduction of mitochondrial membrane potential (MMP) was not reversed by NAC. In the presence of TL/10 illumination, ApoG2 generated massive amounts of singlet oxygen and was more effective in inhibiting cell growth than in the absence of illumination. We also determined the influence of light on the anti-proliferative activity of ApoG2 using a CNE-2–xenograft mouse model. ApoG2 under TL/10 illumination healed tumor wounds and suppressed tumor growth more effectively than ApoG2 treatment alone. These results indicate that the ApoG2-induced CNE-2 cell death is partly ROS-dependent. ApoG2 may be used with photodynamic therapy (PDT) to treat NPC. PMID:21192843

  12. Induction of reactive oxygen species generation inhibits epithelial-mesenchymal transition and promotes growth arrest in prostate cancer cells.

    PubMed

    Das, Trinath P; Suman, Suman; Damodaran, Chendil

    2014-07-01

    Oxidative stress is one causative factor of the pathogenesis and aggressiveness of most of the cancer types, including prostate cancer (CaP). A moderate increase in reactive oxygen species (ROS) induces cell proliferation whereas excessive amounts of ROS promote apoptosis. In this study, we explored the pro-oxidant property of 3,9-dihydroxy-2-prenylcoumestan (psoralidin [pso]), a dietary agent, on CaP (PC-3 and C4-2B) cells. Pso greatly induced ROS generation (more than 20-fold) that resulted in the growth inhibition of CaP cells. Overexpression of anti-oxidant enzymes superoxide dismutase 1 (SOD1), SOD2, and catalase, or pretreatment with the pharmacological inhibitor N-acetylcysteine (NAC) significantly attenuated both pso-mediated ROS generation and pso-mediated growth inhibition in CaP cells. Furthermore, pso administration significantly inhibited the migratory and invasive property of CaP cells by decreasing the transcription of β-catenin, and slug, which promote epithelial-mesenchymal transition (EMT), and by concurrently inducing E-cadherin expression in CaP cells. Pso-induced ROS generation in CaP cells resulted in loss of mitochondrial membrane potential, cytochrome-c release, and activation of caspase-3 and -9 and poly (ADP-ribose) polymerase (PARP), which led to apoptosis. On the other hand, overexpression of anti-oxidants rescued pso-mediated effects on CaP cells. These findings suggest that increasing the threshold of intracellular ROS could prevent or treat CaP growth and metastasis. PMID:23475579

  13. Complex I-mediated reactive oxygen species generation: modulation by cytochrome c and NAD(P)+ oxidation-reduction state.

    PubMed Central

    Kushnareva, Yulia; Murphy, Anne N; Andreyev, Alexander

    2002-01-01

    Several lines of evidence indicate that mitochondrial reactive oxygen species (ROS) generation is the major source of oxidative stress in the cell. It has been shown that ROS production accompanies cytochrome c release in different apoptotic paradigms, but the site(s) of ROS production remain obscure. In the current study, we demonstrate that loss of cytochrome c by mitochondria oxidizing NAD(+)-linked substrates results in a dramatic increase of ROS production and respiratory inhibition. This increased ROS production can be mimicked by rotenone, a complex I inhibitor, as well as other chemical inhibitors of electron flow that act further downstream in the electron transport chain. The effects of cytochrome c depletion from mitoplasts on ROS production and respiration are reversible upon addition of exogenous cytochrome c. Thus in these models of mitochondrial injury, a primary site of ROS generation in both brain and heart mitochondria is proximal to the rotenone inhibitory site, rather than in complex III. ROS production at complex I is critically dependent upon a highly reduced state of the mitochondrial NAD(P)(+) pool and is achieved upon nearly complete inhibition of the respiratory chain. Redox clamp experiments using the acetoacetate/L-beta-hydroxybutyrate couple in the presence of a maximally inhibitory rotenone concentration suggest that the site is approx. 50 mV more electronegative than the NADH/NAD(+) couple. In the absence of inhibitors, this highly reduced state of mitochondria can be induced by reverse electron flow from succinate to NAD(+), accounting for profound ROS production in the presence of succinate. These results lead us to propose a model of thermodynamic control of mitochondrial ROS production which suggests that the ROS-generating site of complex I is the Fe-S centre N-1a. PMID:12180906

  14. Cell uptake, intracellular distribution, fate and reactive oxygen species generation of polymer brush engineered CeO2-x NPs

    NASA Astrophysics Data System (ADS)

    Qiu, Yuan; Rojas, Elena; Murray, Richard A.; Irigoyen, Joseba; Gregurec, Danijela; Castro-Hartmann, Pablo; Fledderman, Jana; Estrela-Lopis, Irina; Donath, Edwin; Moya, Sergio E.

    2015-04-01

    Cerium Oxide nanoparticles (CeO2-x NPs) are modified with polymer brushes of negatively charged poly (3-sulfopropylmethacrylate) (PSPM) and positively charged poly (2-(methacryloyloxy)ethyl-trimethylammonium chloride) (PMETAC) by Atom Transfer Radical Polymerisation (ATRP). CeO2-x NPs are fluorescently labelled by covalently attaching Alexa Fluor® 488/Fluorescein isothiocyanate to the NP surface prior to polymerisation. Cell uptake, intracellular distribution and the impact on the generation of intracellular Reactive Oxygen Species (ROS) with respect to CeO2-x NPs are studied by means of Raman Confocal Microscopy (CRM), Transmission Electron Microscopy (TEM) and Inductively Coupled Plasma Mass Spectroscopy (ICP-MS). PSPM and PMETAC coated CeO2-x NPs show slower and less uptake compared to uncoated Brush modified NPs display a higher degree of co-localisation with cell endosomes and lysosomes after 24 h of incubation. They also show higher co-localisation with lipid bodies when compared to unmodified CeO2-x NPs. The brush coating does not prevent CeO2-x NPs from displaying antioxidant properties.Cerium Oxide nanoparticles (CeO2-x NPs) are modified with polymer brushes of negatively charged poly (3-sulfopropylmethacrylate) (PSPM) and positively charged poly (2-(methacryloyloxy)ethyl-trimethylammonium chloride) (PMETAC) by Atom Transfer Radical Polymerisation (ATRP). CeO2-x NPs are fluorescently labelled by covalently attaching Alexa Fluor® 488/Fluorescein isothiocyanate to the NP surface prior to polymerisation. Cell uptake, intracellular distribution and the impact on the generation of intracellular Reactive Oxygen Species (ROS) with respect to CeO2-x NPs are studied by means of Raman Confocal Microscopy (CRM), Transmission Electron Microscopy (TEM) and Inductively Coupled Plasma Mass Spectroscopy (ICP-MS). PSPM and PMETAC coated CeO2-x NPs show slower and less uptake compared to uncoated Brush modified NPs display a higher degree of co-localisation with cell

  15. Combustion-derived flame generated ultrafine soot generates reactive oxygen species and activates Nrf2 antioxidants differently in neonatal and adult rat lungs

    PubMed Central

    2013-01-01

    Background Urban particulate matter (PM) has been epidemiologically correlated with multiple cardiopulmonary morbidities and mortalities, in sensitive populations. Children exposed to PM are more likely to develop respiratory infections and asthma. Although PM originates from natural and anthropogenic sources, vehicle exhaust rich in polycyclic aromatic hydrocarbons (PAH) can be a dominant contributor to the PM2.5 and PM0.1 fractions and has been implicated in the generation of reactive oxygen species (ROS). Objectives Current studies of ambient PM are confounded by the variable nature of PM, so we utilized a previously characterized ethylene-combusted premixed flame particles (PFP) with consistent and reproducible physiochemical properties and 1) measured the oxidative potential of PFP compared to ambient PM, 2) determined the ability of PFPs to generate oxidative stress and activate the transcription factor using in vitro and ex vivo models, and 3) we correlated these responses with antioxidant enzyme expression in vivo. Methods We compared oxidative stress response (HMOX1) and antioxidant enzyme (SOD1, SOD2, CAT, and PRDX6) expression in vivo by performing a time-course study in 7-day old neonatal and young adult rats exposed to a single 6-hour exposure to 22.4 μg/m3 PFPs. Results We showed that PFP is a potent ROS generator that induces oxidative stress and activates Nrf2. Induction of the oxidative stress responsive enzyme HMOX1 in vitro was mediated through Nrf2 activation and was variably upregulated in both ages. Furthermore, antioxidant enzyme expression had age and lung compartment variations post exposure. Of particular interest was SOD1, which had mRNA and protein upregulation in adult parenchyma, but lacked a similar response in neonates. Conclusions We conclude that PFPs are effective ROS generators, comparable to urban ambient PM2.5, that induce oxidative stress in neonatal and adult rat lungs. PFPs upregulate a select set of antioxidant enzymes in

  16. Methodological considerations of electron spin resonance spin trapping techniques for measuring reactive oxygen species generated from metal oxide nanomaterials

    PubMed Central

    Jeong, Min Sook; Yu, Kyeong-Nam; Chung, Hyun Hoon; Park, Soo Jin; Lee, Ah Young; Song, Mi Ryoung; Cho, Myung-Haing; Kim, Jun Sung

    2016-01-01

    Qualitative and quantitative analyses of reactive oxygen species (ROS) generated on the surfaces of nanomaterials are important for understanding their toxicity and toxic mechanisms, which are in turn beneficial for manufacturing more biocompatible nanomaterials in many industrial fields. Electron spin resonance (ESR) is a useful tool for detecting ROS formation. However, using this technique without first considering the physicochemical properties of nanomaterials and proper conditions of the spin trapping agent (such as incubation time) may lead to misinterpretation of the resulting data. In this report, we suggest methodological considerations for ESR as pertains to magnetism, sample preparation and proper incubation time with spin trapping agents. Based on our results, each spin trapping agent should be given the proper incubation time. For nanomaterials having magnetic properties, it is useful to remove these nanomaterials via centrifugation after reacting with spin trapping agents. Sonication for the purpose of sample dispersion and sample light exposure should be controlled during ESR in order to enhance the obtained ROS signal. This report will allow researchers to better design ESR spin trapping applications involving nanomaterials. PMID:27194379

  17. Methodological considerations of electron spin resonance spin trapping techniques for measuring reactive oxygen species generated from metal oxide nanomaterials

    NASA Astrophysics Data System (ADS)

    Jeong, Min Sook; Yu, Kyeong-Nam; Chung, Hyun Hoon; Park, Soo Jin; Lee, Ah Young; Song, Mi Ryoung; Cho, Myung-Haing; Kim, Jun Sung

    2016-05-01

    Qualitative and quantitative analyses of reactive oxygen species (ROS) generated on the surfaces of nanomaterials are important for understanding their toxicity and toxic mechanisms, which are in turn beneficial for manufacturing more biocompatible nanomaterials in many industrial fields. Electron spin resonance (ESR) is a useful tool for detecting ROS formation. However, using this technique without first considering the physicochemical properties of nanomaterials and proper conditions of the spin trapping agent (such as incubation time) may lead to misinterpretation of the resulting data. In this report, we suggest methodological considerations for ESR as pertains to magnetism, sample preparation and proper incubation time with spin trapping agents. Based on our results, each spin trapping agent should be given the proper incubation time. For nanomaterials having magnetic properties, it is useful to remove these nanomaterials via centrifugation after reacting with spin trapping agents. Sonication for the purpose of sample dispersion and sample light exposure should be controlled during ESR in order to enhance the obtained ROS signal. This report will allow researchers to better design ESR spin trapping applications involving nanomaterials.

  18. Induction of apoptosis by three marine algae through generation of reactive oxygen species in human leukemic cell lines.

    PubMed

    Huang, Huey-Lan; Wu, Shwu-Li; Liao, Hui-Fen; Jiang, Chii-Ming; Huang, Ray-Ling; Chen, Yu-Yawn; Yang, Yuh-Cheng; Chen, Yu-Jen

    2005-03-01

    In this study, we examined the antitumor effect of marine algae extracts on human hepatoma and leukemia cells. Ethyl acetate extracts from Colpomenia sinuosa (Cs-EA), Halimeda discoidae (Hd-EA), and Galaxaura oblongata (Go-EA) directly inhibited the growth of human hepatoma HuH-7 cells and leukemia U937 and HL-60 cells in a time- and dose-dependent manner. Specifically, these algae extracts induced apoptosis of U937 and HL-60 cells as evaluated by detection of hypodiploid cells using flow cytometry and observation of condensed and fragmented nuclei in algae extract-treated cells. Intracellular reactive oxygen species (ROS), especially hydrogen peroxide and superoxide anion, were increased about 2-3-fold in U937 cells treated with Cs-EA for 3-5 h. Interestingly, antioxidant N-acetylcysteine effectively blocked Cs-EA-, Hd-EA-, and Go-EA-induced apoptosis, suggesting that ROS is a key mediator in the apoptotic signaling pathway. In conclusion, our results show that algae extracts induce apoptosis in human leukemia cells through generation of ROS. PMID:15740073

  19. Methodological considerations of electron spin resonance spin trapping techniques for measuring reactive oxygen species generated from metal oxide nanomaterials.

    PubMed

    Jeong, Min Sook; Yu, Kyeong-Nam; Chung, Hyun Hoon; Park, Soo Jin; Lee, Ah Young; Song, Mi Ryoung; Cho, Myung-Haing; Kim, Jun Sung

    2016-01-01

    Qualitative and quantitative analyses of reactive oxygen species (ROS) generated on the surfaces of nanomaterials are important for understanding their toxicity and toxic mechanisms, which are in turn beneficial for manufacturing more biocompatible nanomaterials in many industrial fields. Electron spin resonance (ESR) is a useful tool for detecting ROS formation. However, using this technique without first considering the physicochemical properties of nanomaterials and proper conditions of the spin trapping agent (such as incubation time) may lead to misinterpretation of the resulting data. In this report, we suggest methodological considerations for ESR as pertains to magnetism, sample preparation and proper incubation time with spin trapping agents. Based on our results, each spin trapping agent should be given the proper incubation time. For nanomaterials having magnetic properties, it is useful to remove these nanomaterials via centrifugation after reacting with spin trapping agents. Sonication for the purpose of sample dispersion and sample light exposure should be controlled during ESR in order to enhance the obtained ROS signal. This report will allow researchers to better design ESR spin trapping applications involving nanomaterials. PMID:27194379

  20. Salinomycin simultaneously induces apoptosis and autophagy through generation of reactive oxygen species in osteosarcoma U2OS cells.

    PubMed

    Kim, Sang-Hun; Choi, Young-Jun; Kim, Kwang-Youn; Yu, Sun-Nyoung; Seo, Young-Kyo; Chun, Sung-Sik; Noh, Kyung-Tae; Suh, Jeung-Tak; Ahn, Soon-Cheol

    2016-04-29

    Salinomycin, a polyether antibiotic, acts as a highly selective potassium ionophore. It was reported to anticancer activity on various cancer cell lines. In this study, salinomycin was examined on apoptosis and autophagy through generation of reactive oxygen species (ROS) in osteosarcoma U2OS cells. Apoptosis, autophagy, mitochondrial membrane potential (MMP) and ROS were analyzed using flow cytometry. Also, expressions of apoptosis- and autophagy-related proteins were determined by western blotting. As a result, salinomycin triggered apoptosis of U2OS cells, which was accompanied by change of MMP and cleavage of caspases-3 and poly (ADP-ribose) polymerase. And salinomycin increased the expression of autophagy-related protein and accumulation of acidic vesicular organelles (AVO). Salinomycin-induced ROS production promotes both apoptosis and autophagy, as evidenced by the result that treatment of N-acetyl-l-cysteine (NAC), a ROS scavenger, attenuated both apoptosis and autophagy. In addition, inhibition of autophagy by 3-methyladenine (3 MA) enhanced the salinoymcin-induced apoptosis. Taken together, these results suggested that salinomycin-induced autophagy, as a survival mechanism, might be a potential strategy through ROS regulation in cancer therapy. PMID:27033598

  1. Cell uptake, intracellular distribution, fate and reactive oxygen species generation of polymer brush engineered CeO(2-x) NPs.

    PubMed

    Qiu, Yuan; Rojas, Elena; Murray, Richard A; Irigoyen, Joseba; Gregurec, Danijela; Castro-Hartmann, Pablo; Fledderman, Jana; Estrela-Lopis, Irina; Donath, Edwin; Moya, Sergio E

    2015-04-21

    Cerium Oxide nanoparticles (CeO(2-x) NPs) are modified with polymer brushes of negatively charged poly (3-sulfopropylmethacrylate) (PSPM) and positively charged poly (2-(methacryloyloxy)ethyl-trimethylammonium chloride) (PMETAC) by Atom Transfer Radical Polymerisation (ATRP). CeO(2-x) NPs are fluorescently labelled by covalently attaching Alexa Fluor® 488/Fluorescein isothiocyanate to the NP surface prior to polymerisation. Cell uptake, intracellular distribution and the impact on the generation of intracellular Reactive Oxygen Species (ROS) with respect to CeO(2-x) NPs are studied by means of Raman Confocal Microscopy (CRM), Transmission Electron Microscopy (TEM) and Inductively Coupled Plasma Mass Spectroscopy (ICP-MS). PSPM and PMETAC coated CeO(2-x) NPs show slower and less uptake compared to uncoated Brush modified NPs display a higher degree of co-localisation with cell endosomes and lysosomes after 24 h of incubation. They also show higher co-localisation with lipid bodies when compared to unmodified CeO(2-x) NPs. The brush coating does not prevent CeO(2-x) NPs from displaying antioxidant properties. PMID:25789459

  2. A mutation in the mitochondrial protein UQCRB promotes angiogenesis through the generation of mitochondrial reactive oxygen species

    SciTech Connect

    Chang, Junghwa; Jung, Hye Jin; Jeong, Seung Hun; Kim, Hyoung Kyu; Han, Jin; Kwon, Ho Jeong

    2014-12-12

    Highlights: • We constructed mitochondrial protein UQCRB mutant stable cell lines on the basis of a human case report. • These mutant cell lines exhibit pro-angiogenic activity with enhanced VEGF expression. • Proliferation of mutant cell lines was regulated by UQCRB inhibitors. • UQCRB may have a functional role in angiogenesis. - Abstract: Ubiquinol-cytochrome c reductase binding protein (UQCRB) is one of the subunits of mitochondrial complex III and is a target protein of the natural anti-angiogenic small molecule terpestacin. Previously, the biological role of UQCRB was thought to be limited to the maintenance of complex III. However, the identification and validation of UQCRB as a target protein of terpestacin enabled the role of UQCRB in oxygen sensing and angiogenesis to be elucidated. To explore the biological role of this protein further, UQCRB mutant stable cell lines were generated on the basis of a human case report. We demonstrated that these cell lines exhibited glycolytic and pro-angiogenic activities via mitochondrial reactive oxygen species (mROS)-mediated HIF1 signal transduction. Furthermore, a morphological abnormality in mitochondria was detected in UQCRB mutant stable cell lines. In addition, the proliferative effect of the UQCRB mutants was significantly regulated by the UQCRB inhibitors terpestacin and A1938. Collectively, these results provide a molecular basis for UQCRB-related biological processes and reveal potential key roles of UQCRB in angiogenesis and mitochondria-mediated metabolic disorders.

  3. Low-Level Laser Therapy Activates NF-kB via Generation of Reactive Oxygen Species in Mouse Embryonic Fibroblasts

    PubMed Central

    Huang, Ying-Ying; Tomkinson, Elizabeth M.; Sharma, Sulbha K.; Kharkwal, Gitika B.; Saleem, Taimur; Mooney, David; Yull, Fiona E.; Blackwell, Timothy S.; Hamblin, Michael R.

    2011-01-01

    Background Despite over forty years of investigation on low-level light therapy (LLLT), the fundamental mechanisms underlying photobiomodulation at a cellular level remain unclear. Methodology/Principal Findings In this study, we isolated murine embryonic fibroblasts (MEF) from transgenic NF-kB luciferase reporter mice and studied their response to 810 nm laser radiation. Significant activation of NF-kB was observed at fluences higher than 0.003 J/cm2 and was confirmed by Western blot analysis. NF-kB was activated earlier (1 hour) by LLLT compared to conventional lipopolysaccharide treatment. We also observed that LLLT induced intracellular reactive oxygen species (ROS) production similar to mitochondrial inhibitors, such as antimycin A, rotenone and paraquat. Furthermore, we observed similar NF-kB activation with these mitochondrial inhibitors. These results, together with inhibition of laser induced NF-kB activation by antioxidants, suggests that ROS play an important role in the laser induced NF-kB signaling pathways. However, LLLT, unlike mitochondrial inhibitors, induced increased cellular ATP levels, which indicates that LLLT also upregulates mitochondrial respiration. Conclusion We conclude that LLLT not only enhances mitochondrial respiration, but also activates the redox-sensitive NFkB signaling via generation of ROS. Expression of anti-apoptosis and pro-survival genes responsive to NFkB could explain many clinical effects of LLLT. PMID:21814580

  4. Organic aerosols associated with the generation of reactive oxygen species (ROS) by water-soluble PM2.5.

    PubMed

    Verma, Vishal; Fang, Ting; Xu, Lu; Peltier, Richard E; Russell, Armistead G; Ng, Nga Lee; Weber, Rodney J

    2015-04-01

    We compare the relative toxicity of various organic aerosol (OA) components identified by an aerosol mass spectrometer (AMS) based on their ability to generate reactive oxygen species (ROS). Ambient fine aerosols were collected from urban (three in Atlanta, GA and one in Birmingham, AL) and rural (Yorkville, GA and Centerville, AL) sites in the Southeastern United States. The ROS generating capability of the water-soluble fraction of the particles was measured by the dithiothreitol (DTT) assay. Water-soluble PM extracts were further separated into the hydrophobic and hydrophilic fractions using a C-18 column, and both fractions were analyzed for DTT activity and water-soluble metals. Organic aerosol composition was measured at selected sites using a high-resolution time-of-flight AMS. Positive matrix factorization of the AMS spectra resolved the organic aerosol into isoprene-derived OA (Isop_OA), hydrocarbon-like OA (HOA), less-oxidized oxygenated OA, (LO-OOA), more-oxidized OOA (MO-OOA), cooking OA (COA), and biomass burning OA (BBOA). The association of the DTT activity of water-soluble PM2.5 (WS_DTT) with these factors was investigated by linear regression techniques. BBOA and MO-OOA were most consistently linked with WS_DTT, with intrinsic water-soluble activities of 151 ± 20 and 36 ± 22 pmol/min/μg, respectively. Although less toxic, MO-OOA was most widespread, contributing to WS_DTT activity at all sites and during all seasons. WS_DTT activity was least associated with biogenic secondary organic aerosol. The OA components contributing to WS_DTT were humic-like substances (HULIS), which are abundantly emitted in biomass burning (BBOA) and include highly oxidized OA from multiple sources (MO-OOA). Overall, OA contributed approximately 60% to the WS_DTT activity, with the remaining probably from water-soluble metals, which were mostly associated with the hydrophilic WS_DTT fraction. PMID:25748105

  5. Mitochondrial handling of excess Ca2+ is substrate-dependent with implications for reactive oxygen species generation

    PubMed Central

    Aldakkak, Mohammed; Stowe, David F.; Dash, Ranjan K.; Camara, Amadou K.S.

    2012-01-01

    Aim The mitochondrial electron transport chain is the major source of reactive oxygen species (ROS) during cardiac ischemia. Several mechanisms modulate ROS production; one is mitochondrial Ca2+ uptake. Here we sought to elucidate the effects of extra-mitochondrial Ca2+ (e[Ca2+]) on ROS production (measured as H2O2 release) from complexes I and III. Results Mitochondria, isolated from guinea pig hearts, were pre-incubated with increasing concentrations of CaCl2 and then energized with the complex I substrate Na+-pyruvate or the complex II substrate Na+-succinate. Mitochondrial H2O2 release rates were assessed after giving either rotenone or antimycin A to inhibit complex I or III, respectively. After pyruvate, mitochondria maintained a fully polarized membrane potential (Δψ, assessed using rhodamine 123) and were able to generate NADH (assessed using autofluorescence) even with excess e[Ca2+] (assessed using CaGreen-5N), whereas they remained partially depolarized and did not generate NADH after succinate. This partial Δψ depolarization with succinate was accompanied by a large release of H2O2 (assessed using amplex red/horseradish peroxidase) with later addition of antimycin A. In the presence of excess e[Ca2+], adding cyclosporine A to inhibit mitochondrial permeability transition pore (mPTP) opening restored Δψ and significantly decreased antimycin A-induced H2O2 release. Conclusions Succinate accumulates during ischemia to become the major substrate utilized by cardiac mitochondria. The inability of mitochondria to maintain a fully polarized Δψ under excess e[Ca2+] when succinate, but not pyruvate, is the substrate may indicate a permeabilization of the mitochondrial membrane which enhances H2O2 emission from complex III during ischemia. PMID:23010495

  6. A new algorithm for real-time optimal dispatch of active and reactive power generation retaining nonlinearity

    SciTech Connect

    Roy, L.; Rao, N.D.

    1983-04-01

    This paper presents a new method for optimal dispatch of real and reactive power generation which is based on cartesian coordinate formulation of economic dispatch problem and reclassification of state and control variables associated with generator buses. The voltage and power at these buses are classified as parametric and functional inequality constraints, and are handled by reduced gradient technique and penalty factor approach respectively. The advantage of this classification is the reduction in the size of the equality constraint model, leading to less storage requirement. The rectangular coordinate formulation results in an exact equality constraint model in which the coefficient matrix is real, sparse, diagonally dominant, smaller in size and need be computed and factorized once only in each gradient step. In addition, Lagragian multipliers are calculated using a new efficient procedure. A natural outcome of these features is the solution of the economic dispatch problem, faster than other methods available to date in the literature. Rapid and reliable convergence is an additional desirable characteristic of the method. Digital simulation results are presented on several IEEE test systems to illustrate the range of application of the method visa-vis the popular Dommel-Tinney (DT) procedure. It is found that the proposed method is more reliable, 3-4 times faster and requires 20-30 percent less storage compared to the DT algorithm, while being just as general. Thus, owing to its exactness, robust mathematical model and less computational requirements, the method developed in the paper is shown to be a practically feasible algorithm for on-line optimal power dispatch.

  7. Copper ions strongly activate the phosphoinositide-3-kinase/Akt pathway independent of the generation of reactive oxygen species.

    PubMed

    Ostrakhovitch, Elena A; Lordnejad, Mohammad Reza; Schliess, Freimut; Sies, Helmut; Klotz, Lars-Oliver

    2002-01-15

    Copper is implicated in metabolic disorders, such as Wilson's disease or Alzheimer's disease. Analysis of signaling pathways regulating cellular survival and function in response to a copper stress is crucial for understanding the pathogenesis of such diseases. Exposure of human skin fibroblasts or HeLa cells to Cu(2+) resulted in a dose- and time-dependent activation of the antiapoptotic kinase Akt/protein kinase B, starting at concentrations as low as 3 microM. Only Cu(II), but not Cu(I), had this effect. Activation of Akt was accompanied by phosphorylation of a downstream target of Akt, glycogen synthase kinase-3. Inhibitors of phosphoinositide-3-kinase (PI3K) completely blocked activation of Akt by Cu(2+), indicating a requirement of PI3K for Cu(2+)-induced activation of Akt. Indeed, cellular PI3K activity was strongly enhanced after exposure to Cu(2+). Copper ions may lead to the formation of reactive oxygen species, such as hydrogen peroxide. Activation of Akt by hydrogen peroxide or growth factors is known to proceed via the activation growth factor receptors. In line with this, pretreatment with inhibitors of growth factor receptor tyrosine kinases blocked activation of Akt by hydrogen peroxide and growth factors, as did a src-family tyrosine kinase inhibitor or the broad-spectrum tyrosine kinase inhibitor genistein. Activation of Akt by Cu(2+), however, remained unimpaired, implying (i) that tyrosine kinase activation is not involved in Cu(2+) activation of Akt and (ii) that activation of the PI3K/Akt pathway by Cu(2+) is initiated independently of that induced by reactive oxygen species. Comparison of the time course of the oxidation of 2',7'-dichlorodihydrofluorescein in copper-treated cells with that of Akt activation led to the conclusion that production of hydroperoxides cannot be an upstream event in copper-induced Akt activation. Rather, both activation of Akt and generation of ROS are proposed to occur in parallel, regulating cell survival after a

  8. C-terminal domain of rodent intestinal mucin Muc3 is proteolytically cleaved in the endoplasmic reticulum to generate extracellular and membrane components.

    PubMed Central

    Wang, Rongquan; Khatri, Ismat A; Forstner, Janet F

    2002-01-01

    Although human MUC3 and rodent Muc3 are both membrane-associated intestinal mucins, the present study has explored the possibility that rodent Muc3 might exist in soluble as well as membrane forms. No evidence was obtained for the existence of soluble splice variants; however, experiments with heterologous cells transfected with cDNA encoding the 381-residue C-terminal domain of rodent Muc3 showed that a definitive proteolytic cleavage occurs during processing in the endoplasmic reticulum. The products consisted of a V5-tagged 30 kDa extracellular glycopeptide and a Myc-tagged 49 kDa membrane-associated glycopeptide. Throughout their cellular transport to the plasma membrane, the two fragments remained associated by non-covalent SDS-sensitive interactions. Site-specific mutagenesis pinpointed the need for glycine and serine residues in the cleavage sequence Leu-Ser-Lys-Gly-Ser-Ile-Val-Val, which is localized between the two epidermal-growth-factor-like motifs of the mucin. A similar cleavage sequence (Phe-Arg-Pro-Gly downward arrow Ser-Val-Val-Val, where downward arrow signifies the cleavage site) has been reported in human MUC1 and analogous sites are present in human MUC3, MUC12 and MUC17. Thus early proteolytic cleavage may be a conserved characteristic of many membrane-associated mucins, possibly as a prelude to later release of their large extracellular domains at cell surfaces. PMID:12027806

  9. The role of water and structure on the generation of reactive oxygen species in peptide/hypericin complexes.

    PubMed

    Souza, Márcia I; Silva, Emerson R; Jaques, Ygor M; Ferreira, Fabio F; Fileti, Eudes E; Alves, Wendel A

    2014-07-01

    Hybrid associates formed between peptide assemblies and fluorophores are attractive mainly because of their unique properties for biomedical applications. Recently, we demonstrated that the production of reactive oxygen species (ROS) by hypericin and their stability in excited states are enhanced upon conjugation with l,l-diphenylalanine microtubes (FF-MNTs). Although the detailed mechanisms responsible for improving the photophysical properties of ROS remain unclear, tentative hypotheses have suggested that the driving force is the growth of overall dipolar moments ascribed either to coupling between aligned H2O dipoles within the ordered structures or to the organization of hypericin molecules on peptide interfaces. To provide new insights on ROS activity in hypericin/FF-MNTs hybrids and further explore the role of water in this respect, we present results obtained from investigations on the behavior of these complexes organized into different crystalline arrangements. Specifically, we monitored and compared the photophysical performance of hypericin bound to FF-MNTs with peptides organized in both hexagonal (water-rich) and orthorhombic (water-free) symmetries. From a theoretical perspective, we present the results of new molecular dynamics simulations that highlight the distinct hypericin/peptide interaction at the interface of FF-MNTs for the different symmetries. As a conclusion, we propose that although water enhances photophysical properties, the organization induced by peptide structures and the availability of a hydrophobic environment surrounding the hypericin/peptide interface are paramount to optimizing ROS generation. The findings presented here provide useful basic research insights for designing peptide/fluorophore complexes with outstanding technological potential. PMID:24845629

  10. Reactivation of Endogenous Genes and Epigenetic Remodeling Are Barriers for Generating Transgene-Free Induced Pluripotent Stem Cells in Pig

    PubMed Central

    Choi, Kwang-Hwan; Park, Jin-Kyu; Son, Dongchan; Hwang, Jae Yeon; Lee, Dong-Kyung; Ka, Hakhyun; Park, Joonghoon; Lee, Chang-Kyu

    2016-01-01

    Cellular reprogramming of committed cells into a pluripotent state can be induced by ectopic expression of genes such as OCT4, SOX2, KLF4, and MYC. Reprogrammed cells can be maintained by activating endogenous pluripotent networks without transgene expression. Although various research groups have attempted to generate pig induced pluripotent stem cells (iPSCs), authentic iPSCs have not be obtained, instead showing dependence on transgene expression. In this study, iPSCs were derived from porcine fetal fibroblasts via drug-inducible vectors carrying human transcription factors (OCT4, SOX2, KLF4, and MYC). Therefore, this study investigated characteristics of iPSCs and reprogramming mechanisms in pig. The iPSCs were stably maintained over an extended period with potential in vitro differentiation into three germ layers. In addition, the pluripotent state of iPSCs was regulated by modulating culture conditions. They showed naive- or primed-like pluripotent states in LIF or bFGF supplemented culture conditions, respectively. However, iPSCs could not be maintained without ectopic expression of transgenes. The cultured iPSCs expressed endogenous transcription factors such as OCT4 and SOX2, but not NANOG (a known gateway to complete reprogramming). Endogenous genes related to mesenchymal-to-epithelial transition (DPPA2, CDH1, EPCAM, and OCLN) were not sufficiently reactivated, as measured by qPCR. DNA methylation analysis for promoters of OCT4, NANOG, and XIST showed that epigenetic reprogramming did not occur in female iPSCs. Based on our results, expression of exogenous genes could not sufficiently activate the essential endogenous genes and remodel the epigenetic milieu to achieve faithful pluripotency in pig. Accordingly, investigating iPSCs could help us improve and develop reprogramming methods by understanding reprogramming mechanisms in pig. PMID:27336671

  11. Generation of reactive oxygen species by a novel berberine–bile acid analog mediates apoptosis in hepatocarcinoma SMMC-7721 cells

    SciTech Connect

    Li, Qingyong; Zhang, Li; Zu, Yuangang; Liu, Tianyu; Zhang, Baoyou; He, Wuna

    2013-04-19

    Graphical abstract: - Highlights: • Anticancer effects of B4, a novel berberine–bile acid analog, were tested. • B4 inhibited cell proliferation in hepatocellular carcinoma cells. • It also stimulated mitochondrial ROS production and membrane depolarization. • Effects of B4 were inhibited by a non-specific ROS scavenger. • Regulation of ROS generation may be a strategy for treating hepatic carcinoma. - Abstract: 2,3-Methenedioxy-9-O-(3′α,7′α-dihydroxy-5′β-cholan-24′-propy-lester) berberine (B4) is a novel berberine–bile acid analog synthesized in our laboratory. Previously, we showed that B4 exerted greater cytotoxicity than berberine in several human cancer cell lines. Therefore, we further evaluated the mechanism governing its anticancer actions in hepatocellular carcinoma SMMC-7721 cells. B4 inhibited the proliferation of SMMC-7721 cells, and stimulated reactive oxygen species (ROS) production and mitochondrial membrane depolarization; anti-oxidant capacity was reduced. B4 also induced the release of cytochrome c from the mitochondria to the cytosol and an increase in poly ADP-ribose polymerase (PARP) cleavage products, reflective of caspase-3 activation. Moreover, B4 induced the nuclear translocation of apoptosis-inducing factor (AIF) and a rise in DNA fragmentation. Pretreatment with the anti-oxidant N-acetylcysteine (NAC) inhibited B4-mediated effects, including cytotoxicity, ROS production, mitochondrial membrane depolarization increase in intracellular Ca{sup 2+}, cytochrome c release, PARP cleavage, and AIF translocation. Our data suggest that B4 induces ROS-triggered caspase-dependent and caspase-independent apoptosis pathways in SMMC-7721 cells and that ROS production may be a specific potential strategy for treating hepatic carcinoma.

  12. Reactivation of Endogenous Genes and Epigenetic Remodeling Are Barriers for Generating Transgene-Free Induced Pluripotent Stem Cells in Pig.

    PubMed

    Choi, Kwang-Hwan; Park, Jin-Kyu; Son, Dongchan; Hwang, Jae Yeon; Lee, Dong-Kyung; Ka, Hakhyun; Park, Joonghoon; Lee, Chang-Kyu

    2016-01-01

    Cellular reprogramming of committed cells into a pluripotent state can be induced by ectopic expression of genes such as OCT4, SOX2, KLF4, and MYC. Reprogrammed cells can be maintained by activating endogenous pluripotent networks without transgene expression. Although various research groups have attempted to generate pig induced pluripotent stem cells (iPSCs), authentic iPSCs have not be obtained, instead showing dependence on transgene expression. In this study, iPSCs were derived from porcine fetal fibroblasts via drug-inducible vectors carrying human transcription factors (OCT4, SOX2, KLF4, and MYC). Therefore, this study investigated characteristics of iPSCs and reprogramming mechanisms in pig. The iPSCs were stably maintained over an extended period with potential in vitro differentiation into three germ layers. In addition, the pluripotent state of iPSCs was regulated by modulating culture conditions. They showed naive- or primed-like pluripotent states in LIF or bFGF supplemented culture conditions, respectively. However, iPSCs could not be maintained without ectopic expression of transgenes. The cultured iPSCs expressed endogenous transcription factors such as OCT4 and SOX2, but not NANOG (a known gateway to complete reprogramming). Endogenous genes related to mesenchymal-to-epithelial transition (DPPA2, CDH1, EPCAM, and OCLN) were not sufficiently reactivated, as measured by qPCR. DNA methylation analysis for promoters of OCT4, NANOG, and XIST showed that epigenetic reprogramming did not occur in female iPSCs. Based on our results, expression of exogenous genes could not sufficiently activate the essential endogenous genes and remodel the epigenetic milieu to achieve faithful pluripotency in pig. Accordingly, investigating iPSCs could help us improve and develop reprogramming methods by understanding reprogramming mechanisms in pig. PMID:27336671

  13. Low level laser therapy activates NF-kB via generation of reactive oxygen species in mouse embryonic fibroblasts

    NASA Astrophysics Data System (ADS)

    Chen, Aaron Chih-Hao; Arany, Praveen R.; Huang, Ying-Ying; Tomkinson, Elizabeth M.; Saleem, Taimur; Yull, Fiona E.; Blackwell, Timothy S.; Hamblin, Michael R.

    2009-02-01

    Despite over forty years of investigation on low-level light therapy (LLLT), the fundamental mechanisms underlying photobiomodulation remain unclear. In this study, we isolated murine embryonic fibroblasts (MEF) from transgenic NF-kB luciferase reporter mice and studied their response to 810-nm laser radiation. Significant activation of NFkB was observed for fluences higher than 0.003 J/cm2. NF-kB activation by laser was detectable at 1-hour time point. Moreover, we demonstrated that laser phosphorylated both IKK α/β and NF-kB 15 minutes after irradiation, which implied that laser activates NF-kB via phosphorylation of IKK α/β. Suspecting mitochondria as the source of NF-kB activation signaling pathway, we demonstrated that laser increased both intracellular reactive oxygen species (ROS) by fluorescence microscopy with dichlorodihydrofluorescein and ATP synthesis by luciferase assay. Mitochondrial inhibitors, such as antimycin A, rotenone and paraquat increased ROS and NF-kB activation but had no effect on ATP. The ROS quenchers N-acetyl-L-cysteine and ascorbic acid abrogated laser-induced NF-kB and ROS but not ATP. These results suggested that ROS might play an important role in the signaling pathway of laser induced NF-kB activation. However, the western blot showed that antimycin A, a mitochondrial inhibitor, did not activate NF-kB via serine phosphorylation of IKK α/β as the laser did. On the other hand, LLLT, unlike mitochondrial inhibitors, induced increased cellular ATP levels, which indicates that light also upregulates mitochondrial respiration. ATP upregulation reached a maximum at 0.3 J/cm2 or higher. We conclude that LLLT not only enhances mitochondrial respiration, but also activates the redox-sensitive transcription factor NF-kB by generating ROS as signaling molecules.

  14. A photoreducible copper(II)-tren complex of practical value: generation of a highly reactive click catalyst.

    PubMed

    Harmand, Lydie; Lambert, Romain; Scarpantonio, Luca; McClenaghan, Nathan D; Lastécouères, Dominique; Vincent, Jean-Marc

    2013-11-25

    A detailed study on the photoreduction of the copper(II) precatalyst 1 to generate a highly reactive cuprous species for the copper(I)-catalyzed alkyne-azide cycloaddition (CuAAC) click reaction is presented. For the photoactive catalyst described herein, the activation is driven by a photoinduced electron transfer (PET) process harnessing a benzophenone-like ketoprofenate chromophore as a photosensitizer, which is equally the counterion. The solvent is shown to play a major role in the Cu(II) to Cu(I) reduction process as the final electron source, and the influence of the solvent nature on the photoreduction efficiency has been studied. Particular attention was paid to the use of water as a potential solvent, aqueous media being particularly appealing for CuAAC processes. The ability to solubilize the copper-tren complexes in water through the formation of inclusion complexes with β-CDs is demonstrated. Data is also provided on the fate of the copper(I)-tren catalytic species when reacting with O2, O2 being used to switch off the catalysis. These data show that partial oxidation of the secondary benzylamine groups of the ligand to benzylimines occurs. Preliminary results show that when prolonged irradiation times are employed a Cu(I) to Cu(0) over-reduction process takes place, leading to the formation of copper nanoparticles (NPs). Finally, the main objective of this work being the development of photoactivable catalysts of practical value for the CuAAC, the catalytic, photolatent, and recycling properties of 1 in water and organic solvents are reported. PMID:24127367

  15. Reactive oxygen and nitrogen (ROS and RNS) species generation and cell death in tomato suspension cultures--Botrytis cinerea interaction.

    PubMed

    Pietrowska, E; Różalska, S; Kaźmierczak, A; Nawrocka, J; Małolepsza, U

    2015-01-01

    This article reports events connected to cell survival and Botrytis cinerea infection development in cell suspension cultures of two tomato cultivars which show different levels of susceptibility to the pathogen: cv. Corindo (more susceptible) and cv. Perkoz (less susceptible). In parallel changes in reactive oxygen (ROS) and nitrogen (RNS) species generation and in S-nitrosoglutathione reductase (GSNOR) activity were studied. In vivo staining methods with acridine orange (AO) and ethidium bromide (EB) as well as fluorescent microscopy were used to assess tomato and B. cinerea cells death. The biochemical studies of ROS and RNS concentrations in plant cell extract were complemented by in vivo ROS and nitric oxide (NO) imaging using nitro blue tetrazolium (NBT), diaminobenzidine (DAB) and diaminofluorescein diacetate (DAF-DA) staining methods, and confocal microscope technique. B. cinerea infection proceeded slower in Perkoz cell cultures. It was evidenced by measuring the pathogen conidia germination and germination tube development in which nuclei revealing cell death dominated. Two different types of tomato cell death were observed: cells with necrotic nuclei dominated in Corindo whereas in Perkoz cells with characteristic of vacuolar death type prevailed. In Perkoz cells, constitutive levels of NO and S-nitrosothiols (SNO) were significantly higher and hydrogen peroxide (H₂O₂) and superoxide anion (O₂(-)) concentrations were slightly higher as compared with Corindo cells. Moreover, increases in these molecule concentrations as a result of B. cinerea inoculation were observed in both, Perkoz and Corindo cell cultures. The enzymatic GSNOR activity seems to be an important player in controlling the SNO level in tomato cells. Involvements of the studied compounds in molecular mechanisms of tomato resistance to B. cinerea are discussed in the paper. PMID:25064634

  16. Silver nanoparticles synthesized from Adenium obesum leaf extract induced DNA damage, apoptosis and autophagy via generation of reactive oxygen species.

    PubMed

    Farah, Mohammad Abul; Ali, Mohammad Ajmal; Chen, Shen-Ming; Li, Ying; Al-Hemaid, Fahad Mohammad; Abou-Tarboush, Faisal Mohammad; Al-Anazi, Khalid Mashay; Lee, Joongku

    2016-05-01

    Silver nanoparticles (AgNPs) are an important class of nanomaterial used for a wide range of industrial and biomedical applications. Adenium obesum is a plant of the family Apocynaceae that is rich in toxic cardiac glycosides; however, there is scarce information on the anticancer potential of its AgNPs. We herein report the novel biosynthesis of AgNPs using aqueous leaf extract of A. obesum (AOAgNPs). The synthesis of AOAgNPs was monitored by color change and ultraviolet-visible spectroscopy (425 nm). It was further characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and transmission electron microscopy (TEM). The FTIR spectra for the AOAgNPs indicated the presence of terpenoids, long chain fatty acids, secondary amide derivatives and proteins that could be responsible for the reduction and capping of the formed AOAgNPs. X-ray diffraction confirmed the crystallinity of the AgNPs. The TEM images revealed mostly spherical particles in the size range of 10-30 nm. The biological properties of novel AOAgNPs were investigated on MCF-7 breast cancer cells. Cell viability was determined by the MTT assay. Generation of reactive oxygen species (ROS), DNA damage, induction of apoptosis and autophagy were assessed. A dose-dependent decrease in the cell viability was observed. The IC50 value was calculated as 217 μg/ml. Both qualitative and quantitative evaluation confirmed about a 2.5 fold increase in the generation of ROS at the highest concentration of 150 μg/ml. A significant (p<0.05) increase in the DNA damage evaluated by comet assay was evident. Flow cytometry revealed an increase in the apoptotic cells (24%) in the AOAgNPs treated group compared to the control. Acridine orange staining of acidic vesicles in exposed cells confirmed the induction of autophagy. These findings suggest that AOAgNPs increased the level of ROS resulting in heightened the DNA damage, apoptosis and autophagy in MCF-7 cells. PMID:26852099

  17. α-Tocopherol protects keratinocytes against ultraviolet A irradiation by suppressing glutathione depletion, lipid peroxidation and reactive oxygen species generation

    PubMed Central

    WU, CHI-MING; CHENG, YA-LI; DAI, YOU-HUA; CHEN, MEI-FEI; WANG, CHEE-CHAN

    2014-01-01

    This study aimed to investigate whether α-tocopherol is able to protect keratinocytes against ultraviolet A (UVA) radiation by increasing glutathione (γ-glutamylcysteinylglycine; GSH) levels or decreasing lipid peroxidation and reactive oxygen species (ROS) generation. The cell survival fraction was 43.6% when keratinocytes were irradiated with UVA at a dose of 8 J/cm2. α-Tocopherol was added prior to UVA irradiation and the cell viability was assayed. The cell survival fractions were 60.2, 77.1, 89.0, 92.9 and 96.2% when α-tocopherol was added at concentrations of 2.9, 5.9, 8.8, 11.8 and 14.7 IU/ml, respectively. These results suggested that α-tocopherol is capable of protecting keratinocytes against UVA irradiation. Furthermore, the levels of GSH, lipid peroxidation and ROS were measured. The levels of GSH were 0.354 and 0.600 mmol/g protein in keratinocytes irradiated with UVA (8 J/cm2) and in non-irradiated cells, respectively, whereas they were 0.364, 0.420, 0.525, 0.540 and 0.545 mmol/g protein when α-tocopherol was added at concentrations of 2.9, 5.9, 8.8, 11.8 and 14.7 IU/ml, respectively. The levels of lipid peroxidation were 20.401 or 5.328 μmol/g [malondialdehyde (MDA)/protein] in keratinocytes irradiated with UVA (8 J/cm2) and in non-irradiated cells, respectively, whereas they were 11.685, 6.544, 5.847, 4.390 and 2.164 μmol/g (MDA/protein) when α-tocopherol was added at concentrations of 2.9, 5.9, 8.8, 11.8 and 14.7 IU/ml, respectively. The levels of ROS were 3,952.17 or 111.87 1/mg protein in keratinocytes irradiated with UVA (8 J/cm2) and in non-irradiated cells, respectively, whereas they were 742.48, 579.36, 358.16, 285.63 and 199.82 1/mg protein when α-tocopherol was added at concentrations of 2.9, 5.9, 8.8, 11.8 and 14.7 IU/ml, respectively. These findings suggested that α-tocopherol protects keratinocytes against UVA irradiation, possibly through increasing the levels of GSH or decreasing the levels of lipid peroxidation and ROS

  18. Phototoxicity of nano titanium dioxides in HaCaT keratinocytes—Generation of reactive oxygen species and cell damage

    SciTech Connect

    Yin, Jun-Jie; Liu, Jun; Ehrenshaft, Marilyn; Roberts, Joan E.; Fu, Peter P.; Mason, Ronald P.; Zhao, Baozhong

    2012-08-15

    Nano-sized titanium dioxide (TiO{sub 2}) is among the top five widely used nanomaterials for various applications. In this study, we determine the phototoxicity of TiO{sub 2} nanoparticles (nano-TiO{sub 2}) with different molecular sizes and crystal forms (anatase and rutile) in human skin keratinocytes under UVA irradiation. Our results show that all nano-TiO{sub 2} particles caused phototoxicity, as determined by the MTS assay and by cell membrane damage measured by the lactate dehydrogenase (LDH) assay, both of which were UVA dose- and nano-TiO{sub 2} dose-dependent. The smaller the particle size of the nano-TiO{sub 2} the higher the cell damage. The rutile form of nano-TiO{sub 2} showed less phototoxicity than anatase nano-TiO{sub 2}. The level of photocytotoxicity and cell membrane damage is mainly dependent on the level of reactive oxygen species (ROS) production. Using polyunsaturated lipids in plasma membranes and human serum albumin as model targets, and employing electron spin resonance (ESR) oximetry and immuno-spin trapping as unique probing methods, we demonstrated that UVA irradiation of nano-TiO{sub 2} can induce significant cell damage, mediated by lipid and protein peroxidation. These overall results suggest that nano-TiO{sub 2} is phototoxic to human skin keratinocytes, and that this phototoxicity is mediated by ROS generated during UVA irradiation. Highlights: ► We evaluate the phototoxicity of nano-TiO{sub 2} with different sizes and crystal forms. ► The smaller the particle size of the nano-TiO{sub 2} the higher the cell damage. ► The rutile form of nano-TiO{sub 2} showed less phototoxicity than anatase nano-TiO{sub 2}. ► ESR oximetry and immuno-spin trapping techniques confirm UVA-induced cell damage. ► Phototoxicity is mediated by ROS generated during UVA irradiation of nano-TiO{sub 2}.

  19. Reactive oxygen species generated by PAH o-quinones cause change-in-function mutations in p53.

    PubMed

    Yu, Deshan; Berlin, Jesse A; Penning, Trevor M; Field, Jeffrey

    2002-06-01

    Polycyclic aromatic hydrocarbons (PAHs) in tobacco smoke may cause human lung cancer via metabolic activation to ultimate carcinogens. p53 is one of the most commonly mutated tumor suppressor genes in this disease. An analysis of the p53 mutational database shows that G to T transversions are a signature mutation of lung cancer. Aldo-keto reductases (AKRs) activate PAH trans-dihydrodiol proximate carcinogens to yield their corresponding reactive and redox-active o-quinones, e.g., benzo[a]pyrene-7,8-dione (BP-7,8-dione). We employed a yeast reporter system to determine whether PAH o-quinones or the ROS they generate cause change-in-function mutations in p53. N-Methyl-N-nitroso-N'-nitro-guanidine, a standard alkylating mutagen was used as a positive control. MNNG caused a dose-dependent increase in mutant yeast colonies and at the highest concentrations 8-14% of the yeast colonies were mutated and were characterized by G:C to A:T transitions in the p53 DNA binding domain. Treatment of p53 cDNA with micromolar concentrations of (+/-)-anti-7,8-dihydroxy-9alpha,10alpha-epoxy-7,8,9,10-tetrahydro-benzo[a]pyrene, (anti-BPDE, an ultimate carcinogen) or sub-micromolar concentrations of BP-7,8-dione in the presence of redox-cycling conditions (NADPH and CuCl(2)) also caused p53 mutations in a dose-dependent manner. We found that no mutants were observed with PAH o-quinones or NADPH alone. p53 mutagenesis by BP-7,8-dione was attenuated by ROS scavengers and completely abrogated by a combination of superoxide dismutase and catalase, indicating that both superoxide anion and hydroxyl radicals were the responsible mutagens. The bulk of the mutations detected were single-point mutations and were not random in occurrence. Over 46% of BP-7,8-dione-induced mutations were G:C to T:A transversions, consistent with the formation of 8-oxo-dGuo or its secondary oxidation products. In addition, 25% of these mutations were at hotspots in p53 which are known to be mutated in lung cancer

  20. Program for certification of waste from contained firing facility: Establishment of waste as non-reactive and discussion of potential waste generation problems

    SciTech Connect

    Green, L.; Garza, R.; Maienschein, J.; Pruneda, C.

    1997-09-30

    Debris from explosives testing in a shot tank that contains 4 weight percent or less of explosive is shown to be non-reactive under the specified testing protocol in the Code of Federal Regulations. This debris can then be regarded as a non-hazardous waste on the basis of reactivity, when collected and packaged in a specified manner. If it is contaminated with radioactive components (e.g. depleted uranium), it can therefore be disposed of as radioactive waste or mixed waste, as appropriate (note that debris may contain other materials that render it hazardous, such as beryllium). We also discuss potential waste generation issues in contained firing operations that are applicable to the planned new Contained Firing Facility (CFF). The goal of this program is to develop and document conditions under which shot debris from the planned Contained Firing Facility (CFF) can be handled, shipped, and accepted for waste disposal as non-reactive radioactive or mixed waste. This report fulfills the following requirements as established at the outset of the program: 1. Establish through testing the maximum level of explosive that can be in a waste and still have it certified as non-reactive. 2. Develop the procedure to confirm the acceptability of radioactive-contaminated debris as non-reactive waste at radioactive waste disposal sites. 3. Outline potential disposal protocols for different CFF scenarios (e.g. misfires with scattered explosive).

  1. Application of simultaneous active and reactive power modulation of superconducting magnetic energy storage unit to damp turbine-generator subsynchronous oscillations

    SciTech Connect

    Wu, Chijui; Lee, Yuangshung )

    1993-03-01

    An active and reactive power (P-Q) simultaneous control scheme which is based on a superconducting magnetic energy storage (SMES) unit is designed to damp out the subsynchronous resonant (SSR) oscillations of a turbine-generator unit. In order to suppress unstable torsional mode oscillations, a proportional-integral-derivative (PID) controller is employed to modulate the active and reactive power input/output of the SMES unit according to speed deviation of the generator shaft. The gains of the proposed PID controller are determined by pole assignment approach based on modal control theory. Eigenvalue analysis of the studied system shows that the PID controller is quite effective over a wide range of operating conditions. Dynamic simulations using the nonlinear system model are also performed to demonstrate the damping effect of the proposed control scheme under disturbance conditions.

  2. Sum-Frequency Generation Spectroscopy for Studying Organic Layers at Water-Air Interfaces: Microlayer Monitoring and Surface Reactivity

    NASA Astrophysics Data System (ADS)

    Laß, Kristian; Kleber, Joscha; Bange, Hermann; Friedrichs, Gernot

    2015-04-01

    The sea surface microlayer, according to commonly accepted terminology, comprises the topmost millimetre of the oceanic water column. It is often enriched with organic matter and is directly influenced by sunlight exposure and gas exchange with the atmosphere, hence making it a place for active biochemistry and photochemistry as well as for heterogeneous reactions. In addition, surface active material either is formed or accumulates directly at the air-water interface and gives rise to very thin layers, sometimes down to monomolecular thickness. This "sea surface nanolayer" determines the viscoelastic properties of the seawater surface and thus may impact the turbulent air-sea gas exchange rates. To this effect, this small scale layer presumably plays an important role for large scale changes of atmospheric trace gas concentrations (e.g., by modulating the ocean carbon sink characteristics) with possible implications for coupled climate models. To date, detailed knowledge about the composition, structure, and reactivity of the sea surface nanolayer is still scarce. Due to its small vertical dimension and the small amount of material, this surfactant layer is very difficult to separate and analyse. A way out is the application of second-order nonlinear optical methods, which make a direct surface-specific and background-free detection of this interfacial layer possible. In recent years, we have introduced the use of vibrational sum frequency generation (VSFG) spectroscopy to gain insight into natural and artificial organic monolayers at the air-water interface. In this contribution, the application of VSFG spectroscopy for the analysis of the sea surface nanolayer will be illustrated. Resulting spectra are interpreted in terms of layer composition and surfactant classes, in particular with respect to carbohydrate-containing molecules such as glycolipids. The partitioning of the detected surfactants into soluble and non-soluble ("wet" and "dry") surfactants will be

  3. Evaluation of reactive oxygen species generating AirOcare system for reducing airborne microbial populations in a meat processing plant

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The microbial contamination of meat and meat products is of continuing concern to the meat industry and regulatory agencies. Air has been established as a source of microbial contamination in slaughter and processing facilities. The objective of this research was to determine the efficacy of reactiv...

  4. Extracellular toxicity of 6-hydroxydopamine on PC12 cells.

    PubMed

    Blum, D; Torch, S; Nissou, M F; Benabid, A L; Verna, J M

    2000-04-14

    6-hydroxydopamine (6-OHDA) is usually thought to cross cell membrane through dopamine uptake transporters, to inhibit mitochondrial respiration and to generate intracellular reactive oxygen species. In this study, we show that the anti-oxidants catalase, glutathione and N-acetyl-cysteine are able to reverse the toxic effects of 6-OHDA. These two latter compounds considerably slow down 6-OHDA oxidation in a cell free system suggesting a direct chemical interaction with the neurotoxin. Moreover, desipramine does not protect PC12 cells and 6-OHDA is also strongly toxic towards non-catecholaminergic C6 and NIH3T3 cells. These results thus suggest that 6-OHDA toxicity on PC12 cells mainly involves an extracellular process. PMID:10754220

  5. UV Light-Induced Generation of Reactive Oxygen Species and Antimicrobial Properties of Cellulose Fabric Modified by 3,3',4,4'-Benzophenone Tetracarboxylic Acid.

    PubMed

    Hou, Aiqin; Feng, Guanchen; Zhuo, Jingyuan; Sun, Gang

    2015-12-23

    3,3',4,4'-Benzophenone tetracarboxylic acid (BPTCA) could directly react with hydroxyl groups on cellulose to form ester bonds. The modified cotton fabrics not only provided good wrinkle-free and ultraviolet (UV) protective functions, but also exhibited important photochemical properties such as producing reactive oxygen species (ROS) including hydroxyl radicals (HO(•)) and hydrogen peroxide (H2O2) under UV light exposure. The amounts of the produced hydroxyl radical and hydrogen peroxide were measured, and photochemical reactive mechanism of the BPTCA treated cellulose was discussed. The results reveal that the fabrics possess good washing durability in generation of hydroxyl radicals and hydrogen peroxide. The cotton fabrics modified with different concentrations of BPTCA and cured at an elevated temperature demonstrated excellent antimicrobial activities, which provided 99.99% antibacterial activities against both E. coli and S. aureus. The advanced materials have potential applications in medical textiles and biological material fields. PMID:26636826

  6. NADPH oxidase-mediated generation of reactive oxygen species: A new mechanism for X-ray-induced HeLa cell death

    SciTech Connect

    Liu Qing; He Xiaoqing; Liu Yongsheng; Du Bingbing; Wang Xiaoyan; Zhang Weisheng; Jia Pengfei; Dong Jingmei; Ma Jianxiu; Wang Xiaohu; Li Sha; Zhang Hong

    2008-12-19

    Oxidative damage is an important mechanism in X-ray-induced cell death. Radiolysis of water molecules is a source of reactive oxygen species (ROS) that contribute to X-ray-induced cell death. In this study, we showed by ROS detection and a cell survival assay that NADPH oxidase has a very important role in X-ray-induced cell death. Under X-ray irradiation, the upregulation of the expression of NADPH oxidase membrane subunit gp91{sup phox} was dose-dependent. Meanwhile, the cytoplasmic subunit p47{sup phox} was translocated to the cell membrane and localized with p22{sup phox} and gp91{sup phox} to form reactive NADPH oxidase. Our data suggest, for the first time, that NADPH oxidase-mediated generation of ROS is an important contributor to X-ray-induced cell death. This suggests a new target for combined gene transfer and radiotherapy.

  7. Allicin protects rat cardiomyoblasts (H9c2 cells) from hydrogen peroxide-induced oxidative injury through inhibiting the generation of intracellular reactive oxygen species.

    PubMed

    Chan, Jackie Yan-Yan; Tsui, Hei-Tung; Chung, Ivan Ying-Ming; Chan, Robbie Yat-Kan; Kwan, Yiu-Wa; Chan, Shun-Wan

    2014-11-01

    Oxidative stress is considered an important factor that promotes cell death in response to a variety of pathophysiological conditions. This study investigated the antioxidant properties of allicin, the principle ingredient of garlic, on preventing oxidative stress-induced injury. The antioxidant capacities of allicin were measured by using 1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging assay and hydrogen peroxide (H(2)O(2))-induced cell damage on H9c2 cardiomyoblasts. Allicin (0.3-10 μM) pre-incubation could concentration-dependently attenuate the intracellular reactive oxygen species (ROS) increase induced by H(2)O(2) on H9c2 cells. It could also protect H9c2 cells against H(2)O(2)-induced cell damage. However, the DPPH free radical scavenging activity of allicin was shown to be low. Therefore, it is believed that the protective effect of allicin on H9c2 cells could inhibit intracellular ROS production instead of scavenging extracellular H(2)O(2) or free radicals. For the observed protective effect on H9c2 cells, allicin might also be effective in reducing free radical-induced myocardial cell death in ischemic condition. PMID:24945597

  8. Sexual Preferences in Nutrient Utilization Regulate Oxygen Consumption and Reactive Oxygen Species Generation in Schistosoma mansoni: Potential Implications for Parasite Redox Biology.

    PubMed

    Oliveira, Matheus P; Correa Soares, Juliana B R; Oliveira, Marcus F

    2016-01-01

    Schistosoma mansoni, one of the causative agents of human schistosomiasis, has a unique antioxidant network that is key to parasite survival and a valuable chemotherapeutic target. The ability to detoxify and tolerate reactive oxygen species increases along S. mansoni development in the vertebrate host, suggesting that adult parasites are more exposed to redox challenges than young stages. Indeed, adult parasites are exposed to multiple redox insults generated from blood digestion, activated immune cells, and, potentially, from their own parasitic aerobic metabolism. However, it remains unknown how reactive oxygen species are produced by S. mansoni metabolism, as well as their biological effects on adult worms. Here, we assessed the contribution of nutrients and parasite gender to oxygen utilization pathways, and reactive oxygen species generation in whole unpaired adult S. mansoni worms. We also determined the susceptibilities of both parasite sexes to a pro-oxidant challenge. We observed that glutamine and serum importantly contribute to both respiratory and non-respiratory oxygen utilization in adult worms, but with different proportions among parasite sexes. Analyses of oxygen utilization pathways revealed that respiratory rates were high in male worms, which contrast with high non-respiratory rates in females, regardless nutritional sources. Interestingly, mitochondrial complex I-III activity was higher than complex IV specifically in females. We also observed sexual preferences in substrate utilization to sustain hydrogen peroxide production towards glucose in females, and glutamine in male worms. Despite strikingly high oxidant levels and hydrogen peroxide production rates, female worms were more resistant to a pro-oxidant challenge than male parasites. The data presented here indicate that sexual preferences in nutrient metabolism in adult S. mansoni worms regulate oxygen utilization and reactive oxygen species production, which may differently contribute

  9. Sexual Preferences in Nutrient Utilization Regulate Oxygen Consumption and Reactive Oxygen Species Generation in Schistosoma mansoni: Potential Implications for Parasite Redox Biology

    PubMed Central

    Oliveira, Matheus P.; Correa Soares, Juliana B. R.; Oliveira, Marcus F.

    2016-01-01

    Schistosoma mansoni, one of the causative agents of human schistosomiasis, has a unique antioxidant network that is key to parasite survival and a valuable chemotherapeutic target. The ability to detoxify and tolerate reactive oxygen species increases along S. mansoni development in the vertebrate host, suggesting that adult parasites are more exposed to redox challenges than young stages. Indeed, adult parasites are exposed to multiple redox insults generated from blood digestion, activated immune cells, and, potentially, from their own parasitic aerobic metabolism. However, it remains unknown how reactive oxygen species are produced by S. mansoni metabolism, as well as their biological effects on adult worms. Here, we assessed the contribution of nutrients and parasite gender to oxygen utilization pathways, and reactive oxygen species generation in whole unpaired adult S. mansoni worms. We also determined the susceptibilities of both parasite sexes to a pro-oxidant challenge. We observed that glutamine and serum importantly contribute to both respiratory and non-respiratory oxygen utilization in adult worms, but with different proportions among parasite sexes. Analyses of oxygen utilization pathways revealed that respiratory rates were high in male worms, which contrast with high non-respiratory rates in females, regardless nutritional sources. Interestingly, mitochondrial complex I-III activity was higher than complex IV specifically in females. We also observed sexual preferences in substrate utilization to sustain hydrogen peroxide production towards glucose in females, and glutamine in male worms. Despite strikingly high oxidant levels and hydrogen peroxide production rates, female worms were more resistant to a pro-oxidant challenge than male parasites. The data presented here indicate that sexual preferences in nutrient metabolism in adult S. mansoni worms regulate oxygen utilization and reactive oxygen species production, which may differently contribute

  10. Generation of reactive oxygen species from 5-aminolevulinic acid and Glutamate in cooperation with excited CdSe/ZnS QDs

    NASA Astrophysics Data System (ADS)

    Duong, Hong Dinh; Lee, Jee Won; Rhee, Jong Il

    2014-08-01

    CdSe/ZnS quantum dots (QDs) can be joined in the reductive pathway involving the electron transfer to an acceptor or in the oxidative pathway involving the hole transfer to a donor. They were exploited in the oxidation reactions of 5-aminolevulinic acid (ALA) and glutamate (GLU) for the generation of reactive oxygen species (ROS) such as hydroxyl radical (HO●) and superoxide anion (O2 ● -). Fast and highly efficient oxidation reactions of ALA to produce HO● and of GLU to produce O2 ●- were observed in the cooperation of mercaptopropionic acid (MPA)-capped CdSe/ZnS QDs under LED irradiation. Fluorescence spectroscopy and electron spin resonance (ESR) spectroscopy were used to evaluate the generation of different forms of ROS. Confocal fluorescent microscopic images of the size and morphology of HeLa cells confirmed the ROS generation from ALA or GLU in cooperation with CdSe/ZnS QDs under LED irradiation.