Science.gov

Sample records for respiratory burst oxidase

  1. Respiratory burst oxidase of fertilization.

    PubMed Central

    Heinecke, J W; Shapiro, B M

    1989-01-01

    Partially reduced oxygen species are toxic, yet sea urchin eggs synthesize H2O2 in a "respiratory burst" at fertilization, as an extracellular oxidant to crosslink their protective surface envelopes. To study the biochemical mechanism for H2O2 production, we have isolated an NADPH-specific oxidase fraction from homogenates of unfertilized Strongylocentrotus purpuratus eggs that produces H2O2 when stimulated with Ca2+ and MgATP2-. Concentrations of free Ca2+ previously implicated in regulation of egg activation modulate the activity of the oxidase. Inhibitors were used to test the relevance of this oxidase to the respiratory burst of fertilization. Procaine, two phenothiazines, and N-ethylmaleimide (but not iodoacetamide) inhibited H2O2 production by the oxidase fraction and oxygen consumption by activated eggs. The ATP requirement suggested that protein kinase activity might regulate the respiratory burst of fertilization; consonant with this hypothesis, H-7 and staurosporine were inhibitory. The respiratory burst oxidase of fertilization is an NADPH:O2 oxidoreductase that appears to be regulated by a protein kinase; although it bears a remarkable resemblance to the neutrophil oxidase, unlike the latter it does not form O2- as its initial product. PMID:2537493

  2. Isolation of the respiratory burst oxidase: the role of a flavoprotein component.

    PubMed

    Parkinson, J F; Gabig, T G

    1988-12-01

    The article reviews the enzymatic and electron transfer properties of a low-potential FAD-dependent flavoprotein that is a component of the NADPH-dependent O2-.-generating respiratory burst oxidase of phagocytes. Current methods available for isolation of the respiratory burst oxidase and the flavoprotein component of the complex are also reviewed. These studies and data obtained from affinity-labeling of respiratory burst oxidase components, suggest that the flavoprotein has a molecular weight of 65-67 kD. The prevailing evidence suggests that the flavoprotein functions as a dehydrogenase/electron transferase and can directly catalyse NADPH-dependent O2-.formation when isolated. However, in neutrophil plasma membranes, the prevailing evidence suggests that the flavoprotein functions primarily to transfer electrons from NADPH to cytochrome b-245 and that this latter redox component is the catalytic side of O2-.formation. A working model for the arrangement of the flavoprotein and cytochrome b-245 components of the respiratory burst oxidase in neutrophil membranes is proposed.

  3. The respiratory burst oxidase of human neutrophils. Further studies of the purified enzyme.

    PubMed

    Glass, G A; DeLisle, D M; DeTogni, P; Gabig, T G; Magee, B H; Markert, M; Babior, B M

    1986-10-05

    A superoxide-forming oxidase from activated human neutrophil membranes was solubilized by two slightly different methods, then purified by "dye-affinity" chromatography. Kinetic studies of the purified preparations gave Vmax values of 5-10 mumol of O-2/min/mg of protein, and Km values for NADH and NADPH that were in reasonable agreement with values determined previously using particulate and crude solubilized preparations of the respiratory burst oxidase. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed prominent bands at 67, 48, and 32 kDa, together with some minor contaminants, whereas gel electrophoresis under non-denaturing conditions gave a single major band that when eluted and re-electrophoresed in the presence of sodium dodecyl sulfate showed bands at 67, 48, 32 kDa. We believe that all three bands represent oxidase components. The flavin content of the purified enzyme was 20.4 +/- 2.0 S.E. pmol of FAD/microgram of protein, whereas heme averaged 0.1 +/- 0.02 pmol/microgram and ubiquinone could not be detected. Assuming that the enzyme is composed of one 67-kDa subunit, one 48-kDa subunit, and one 32-kDa subunit (i.e. that its molecular mass is approximately 150 kDa), it can be calculated to have a turnover number of 700-1500 min-1, in agreement with a value reported previously for oxidase in a particulate O-2-forming system (Cross, A. R., Parkinson, J. F., and Jones, O. T. G. (1985) Biochem. J. 226, 881-884), and to contain the following quantities of redox carriers (mol/mol): FAD, 3.0; heme, 0.015; ubiquinone, less than 0.06. It remains to be determined whether this preparation represents the complete respiratory burst oxidase or is only the pyridine nucleotide dehydrogenating component of a more complex enzyme.

  4. Genome-Wide Analysis of Respiratory Burst Oxidase Homologs in Grape (Vitis vinifera L.)

    PubMed Central

    Cheng, Chenxia; Xu, Xiaozhao; Gao, Min; Li, Jun; Guo, Chunlei; Song, Junyang; Wang, Xiping

    2013-01-01

    Plant respiratory burst oxidase homolog (rboh) genes appear to play crucial roles in plant development, defense reactions and hormone signaling. In this study, a total of seven rboh genes from grape were identified and characterized. Genomic structure and predicted protein sequence analysis indicated that the sequences of plant rboh genes are highly conserved. Synteny analysis demonstrated that several Vvrboh genes were found in corresponding syntenic blocks of Arabidopsis, suggesting that these genes arose before the divergence of the respective lineages. The expression pattern of Vvrboh genes in different tissues was assessed by qRT-PCR and two were constitutively expressed in all tissues tested. The expression profiles were similarly analyzed following exposure to various stresses and hormone treatments. It was shown that the expression levels of VvrbohA, VvrbohB and VvrbohC1 were significantly increased by salt and drought treatments. VvrbohB, VvrbohC2, and VvrbohD exhibited a dramatic up-regulation after powdery mildew (Uncinula necator (Schw.) Burr.) inoculation, while VvrbohH was down-regulated. Finally, salicylic acid treatment strongly stimulated the expression of VvrbohD and VvrbohH, while abscisic acid treatment induced the expression of VvrbohB and VvrbohH. These results demonstrate that the expression patterns of grape rboh genes exhibit diverse and complex stress-response expression signatures. PMID:24351809

  5. Rapid deactivation of NADPH oxidase in neutrophils: continuous replacement by newly activated enzyme sustains the respiratory burst.

    PubMed

    Akard, L P; English, D; Gabig, T G

    1988-07-01

    The cell-free system for activation of the neutrophil NADPH oxidase allowed us to examine activation of the oxidase in the absence of its NADPH-dependent turnover. The covalent sulfhydryl-modifying reagent N-ethylmaleimide completely inhibited the activation step (Ki = 40 mumol/L) in the cell-free system but had no effect on turnover of the preactivated particulate NADPH oxidase (up to 1 mmol/L). When N-ethylmaleimide was added to intact neutrophils during the period of maximal O2 generation in response to stimuli that activate the respiratory burst (phorbol myristate acetate, f-Met-Leu-Phe, opsonized zymosan, arachidonic acid), O2- generation ceased within seconds. Study of components of the cell-free activation system indicated that the cytosolic cofactor was irreversibly inhibited by N-ethylmaleimide whereas the N-ethylmaleimide-treated, membrane-associated oxidase could be activated by arachidonate and control cytosolic cofactor. Likewise, the cell-free system prepared from intact neutrophils that had been briefly exposed to N-ethylmaleimide and then washed reflected the effects of N-ethylmaleimide on the isolated cell-free components: cytosolic cofactor activity was absent, but the membrane oxidase remained fully activatable. Thus inhibition of oxidase activation by N-ethylamaleimide unmasked a rapid deactivation step that was operative in intact neutrophils but not in isolated particulate NADPH oxidase preparations. The demonstrated specificity of N-ethylmaleimide for oxidase activation and lack of effect on turnover of the NADPH oxidase suggested that sustained O2- generation by intact neutrophils was a result of continued replenishment of a small pool of active oxidase. The existence of an inactive pool of NADPH oxidase molecules in particulate preparations from stimulated neutrophils was supported more directly by activating these preparations again in the cell-free system.

  6. The phosphorylation targets of p47phox, a subunit of the respiratory burst oxidase. Functions of the individual target serines as evaluated by site-directed mutagenesis.

    PubMed Central

    Faust, L R; el Benna, J; Babior, B M; Chanock, S J

    1995-01-01

    The respiratory burst oxidase of phagocytes and B lymphocytes catalyzes the reduction of oxygen to O2- at the expense of NADPH. Dormant in resting cells, the oxidase is activated by exposing the cells to appropriate stimuli. During activation, p47phox, a cytosolic oxidase subunit, becomes extensively phosphorylated on a number of serines located between S303 and S379. To determine whether this phosphorylation is necessary for oxidase activation, we examined phorbol-elicited oxidase activity in EBV-transformed B lymphoblasts deficient in p47phox after transfection with plasmids expressing various S-->A mutants of p47phox. The mutant containing S-->A mutations involving all serines between S303 and S379 [S(303-379)A] was not phosphorylated, did not translocate to plasma membrane during activation and was almost devoid of function. As to individual serines, S379 was of special interest because (a) p47 phox S379 was phosphorylated in phorbol-activated lymphoblasts expressing wild-type p47phox, and (b) p47phox S379A failed to translocate to the membrane, and was as functionless as p47phox S(303-379)A; other single S-->A mutations had little effect on oxidase activity. These findings suggest that the phosphorylation of S379 may be important for oxidase activation in whole cells. Images PMID:7657821

  7. Cloning and expression analysis of the Ccrboh gene encoding respiratory burst oxidase in Citrullus colocynthis and grafting onto Citrullus lanatus (watermelon).

    PubMed

    Si, Ying; Dane, Fenny; Rashotte, Aaron; Kang, Kwonkyoo; Singh, Narendra K

    2010-06-01

    A full-length drought-responsive gene Ccrboh, encoding the respiratory burst oxidase homologue (rboh), was cloned in Citrullus colocynthis, a very drought-tolerant cucurbit species. The robh protein, also named NADPH oxidase, is conserved in plants and animals, and functions in the production of reactive oxygen species (ROS). The Ccrboh gene accumulated in a tissue-specific pattern when C. colocynthis was treated with PEG, abscisic acid (ABA), salicylic acid (SA), jasmonic acid (JA), or NaCl, while the homologous rboh gene did not show any change in C. lanatus var. lanatus, cultivated watermelon, during drought. Grafting experiments were conducted using C. colocynthis or C. lanatus as the rootstock or scion. Results showed that the rootstock significantly affects gene expression in the scion, and some signals might be transported from the root to the shoot. Ccrboh in C. colocynthis was found to function early during plant development, reaching high mRNA transcript levels 3 d after germination. The subcellular location of Ccrboh was investigated by transient expression of the 35S::Ccrboh::GFP fusion construct in protoplasts. The result confirmed that Ccrboh is a transmembrane protein. Our data suggest that Ccrboh might be functionally important during the acclimation of plants to stress and also in plant development. It holds great promise for improving drought tolerance of other cucurbit species.

  8. ETHYLENE RESPONSE FACTOR 74 (ERF74) plays an essential role in controlling a respiratory burst oxidase homolog D (RbohD)-dependent mechanism in response to different stresses in Arabidopsis.

    PubMed

    Yao, Yuan; He, Run Jun; Xie, Qiao Li; Zhao, Xian Hai; Deng, Xiao Mei; He, Jun Bo; Song, Lili; He, Jun; Marchant, Alan; Chen, Xiao-Yang; Wu, Ai-Min

    2017-03-01

    Recent studies indicate that the ETHYLENE RESPONSE FACTOR VII (ERF-VII) transcription factor is an important regulator of osmotic and hypoxic stress responses in plants. However, the molecular mechanism of ERF-VII-mediated transcriptional regulation remains unclear. Here, we investigated the role of ERF74 (a member of the ERF-VII protein family) by examining the abiotic stress tolerance of an ERF74 overexpression line and a T-DNA insertion mutant using flow cytometry, transactivation and electrophoretic mobility shift assays. 35S::ERF74 showed enhanced tolerance to drought, high light, heat and aluminum stresses, whereas the T-DNA insertion mutant erf74 and the erf74;erf75 double mutant displayed higher sensitivity. Using flow cytometry analysis, we found that erf74 and erf74;erf75 lines lack the reactive oxygen species (ROS) burst in the early stages of various stresses, as a result of the lower expression level of RESPIRATORY BURST OXIDASE HOMOLOG D (RbohD). Furthermore, ERF74 directly binds to the promoter of RbohD and activates its expression under different abiotic stresses. Moreover, induction of stress marker genes and ROS-scavenging enzyme genes under various stress conditions is dependent on the ERF74-RbohD-ROS signal pathway. We propose a pathway that involves ERF74 acting as an on-off switch controlling an RbohD-dependent mechanism in response to different stresses, subsequently maintaining hydrogen peroxide (H2 O2 ) homeostasis in Arabidopsis.

  9. High atmospheric carbon dioxide-dependent alleviation of salt stress is linked to RESPIRATORY BURST OXIDASE 1 (RBOH1)-dependent H2O2 production in tomato (Solanum lycopersicum)

    PubMed Central

    Yi, Changyu; Yao, Kaiqian; Cai, Shuyu; Li, Huizi; Zhou, Jie; Xia, Xiaojian; Shi, Kai; Yu, Jingquan; Foyer, Christine Helen; Zhou, Yanhong

    2015-01-01

    Plants acclimate rapidly to stressful environmental conditions. Increasing atmospheric CO2 levels are predicted to influence tolerance to stresses such as soil salinity but the mechanisms are poorly understood. To resolve this issue, tomato (Solanum lycopersicum) plants were grown under ambient (380 μmol mol–1) or high (760 μmol mol–1) CO2 in the absence or presence of sodium chloride (100mM). The higher atmospheric CO2 level induced the expression of RESPIRATORY BURST OXIDASE 1 (SlRBOH1) and enhanced H2O2 accumulation in the vascular cells of roots, stems, leaf petioles, and the leaf apoplast. Plants grown with higher CO2 levels showed improved salt tolerance, together with decreased leaf transpiration rates and lower sodium concentrations in the xylem sap, vascular tissues, and leaves. Silencing SlRBOH1 abolished high CO2 -induced salt tolerance and increased leaf transpiration rates, as well as enhancing Na+ accumulation in the plants. The higher atmospheric CO2 level increased the abundance of a subset of transcripts involved in Na+ homeostasis in the controls but not in the SlRBOH1-silenced plants. It is concluded that high atmospheric CO2 concentrations increase salt stress tolerance in an apoplastic H2O2 dependent manner, by suppressing transpiration and hence Na+ delivery from the roots to the shoots, leading to decreased leaf Na+ accumulation. PMID:26417022

  10. High atmospheric carbon dioxide-dependent alleviation of salt stress is linked to RESPIRATORY BURST OXIDASE 1 (RBOH1)-dependent H2O2 production in tomato (Solanum lycopersicum).

    PubMed

    Yi, Changyu; Yao, Kaiqian; Cai, Shuyu; Li, Huizi; Zhou, Jie; Xia, Xiaojian; Shi, Kai; Yu, Jingquan; Foyer, Christine Helen; Zhou, Yanhong

    2015-12-01

    Plants acclimate rapidly to stressful environmental conditions. Increasing atmospheric CO2 levels are predicted to influence tolerance to stresses such as soil salinity but the mechanisms are poorly understood. To resolve this issue, tomato (Solanum lycopersicum) plants were grown under ambient (380 μmol mol(-1)) or high (760 μmol mol(-1)) CO2 in the absence or presence of sodium chloride (100mM). The higher atmospheric CO2 level induced the expression of RESPIRATORY BURST OXIDASE 1 (SlRBOH1) and enhanced H2O2 accumulation in the vascular cells of roots, stems, leaf petioles, and the leaf apoplast. Plants grown with higher CO2 levels showed improved salt tolerance, together with decreased leaf transpiration rates and lower sodium concentrations in the xylem sap, vascular tissues, and leaves. Silencing SlRBOH1 abolished high CO2 -induced salt tolerance and increased leaf transpiration rates, as well as enhancing Na(+) accumulation in the plants. The higher atmospheric CO2 level increased the abundance of a subset of transcripts involved in Na(+) homeostasis in the controls but not in the SlRBOH1-silenced plants. It is concluded that high atmospheric CO2 concentrations increase salt stress tolerance in an apoplastic H2O2 dependent manner, by suppressing transpiration and hence Na(+) delivery from the roots to the shoots, leading to decreased leaf Na(+) accumulation.

  11. Tamoxifen does not inhibit the swell activated chloride channel in human neutrophils during the respiratory burst

    SciTech Connect

    Ahluwalia, Jatinder

    2008-10-31

    Effective functioning of neutrophils relies upon electron translocation through the NADPH oxidase (NOX). The electron current generated (I{sub e}) by the neutrophil NADPH oxidase is electrogenic and rapidly depolarises the membrane potential in activated human neutrophils. Swelling activated chloride channels have been demonstrated in part to counteract the depolarisation generated by the NADPH oxidase I{sub e}. In the present study, the effects of inhibitors of swell activated chloride channels on ROS production and on the swelling activated chloride conductance was investigated in activated human neutrophils. Tamoxifen (10 {mu}M), a specific inhibitor for swell activated chloride channels in neutrophils, completely inhibited both the PMA and FMLP stimulated respiratory burst. This inhibition of the neutrophil respiratory burst was not due to the blocking effect of tamoxifen on the swelling activated chloride conductance in these cells. These results demonstrate that a tamoxifen insensitive swell activated chloride channel has important significance during the neutrophil respiratory burst.

  12. Proton stoichiometry associated with human neutrophil respiratory-burst reactions.

    PubMed

    Gabig, T G; Lefker, B A; Ossanna, P J; Weiss, S J

    1984-11-10

    Control of the intraphagosomal pH in neutrophils may be of importance in creating a microbicidal environment by regulating the activity of the O2-.-generating NADPH oxidase and the lysosomal enzymes discharged into this compartment. In this study, we examined the proton stoichiometry associated with the primary enzymatic reaction underlying the respiratory burst. A preparation of the neutrophil-derived, membrane oxidase consumed NADPH and generated O2-. with a stoichiometry of 1 NADPH:2 O2-. When the enzymatically produced O2-. was prevented from undergoing dismutation, net protons were released in an approximate 1:2 stoichiometry with O2-. generated. In contrast, when O2-. was allowed to dismutate to H2O2, net protons were consumed in a 1:1 stoichiometry with the accumulated H2O2. Thus, the delta pH associated with the NADPH oxidase-dependent production of O2-. was dictated by the fate of the generated radical. The consumption of the oxidase-generated H2O2 by the lysosomal enzyme myeloperoxidase resulted in the formation of HOCl which was trapped in the presence of taurine as the N-chloro derivative. The ratio of chlorinated product formed to H+ consumed was 1:1. The implications of these results are discussed in terms of the known intraphagosomal pH changes that occur following neutrophil stimulation. We conclude that the O2-.-generating oxidase plays a dual role in the phagosome by simultaneously creating an oxidizing environment that optimizes pH-dependent microbicidal processes.

  13. Diacylglycerol kinases activate tobacco NADPH oxidase-dependent oxidative burst in response to cryptogein.

    PubMed

    Cacas, Jean-Luc; Gerbeau-Pissot, Patricia; Fromentin, Jérôme; Cantrel, Catherine; Thomas, Dominique; Jeannette, Emmanuelle; Kalachova, Tetiana; Mongrand, Sébastien; Simon-Plas, Françoise; Ruelland, Eric

    2017-04-01

    Cryptogein is a 10 kDa protein secreted by the oomycete Phytophthora cryptogea that activates defence mechanisms in tobacco plants. Among early signalling events triggered by this microbial-associated molecular pattern is a transient apoplastic oxidative burst which is dependent on the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity of the RESPIRATORY BURST OXIDASE HOMOLOG isoform D (RBOHD). Using radioactive [(33) P]-orthophosphate labelling of tobacco Bright Yellow-2 suspension cells, we here provide in vivo evidence for a rapid accumulation of phosphatidic acid (PA) in response to cryptogein because of the coordinated onset of phosphoinositide-dependent phospholipase C and diacylglycerol kinase (DGK) activities. Both enzyme specific inhibitors and silencing of the phylogenetic cluster III of the tobacco DGK family were found to reduce PA production upon elicitation and to strongly decrease the RBOHD-mediated oxidative burst. Therefore, it appears that PA originating from DGK controls NADPH-oxidase activity. Amongst cluster III DGKs, the expression of DGK5-like was up-regulated in response to cryptogein. Besides DGK5-like is likely to be the main cluster III DGK isoform silenced in one of our mutant lines, making it a strong candidate for the observed response to cryptogein. The relevance of these results is discussed with regard to early signalling lipid-mediated events in plant immunity.

  14. ADP stimulates the respiratory burst without activation of ERK and AKT in rat alveolar macrophages.

    PubMed

    Gozal, E; Forman, H J; Torres, M

    2001-09-01

    Alveolar macrophages (AM) are the first line of defense against infection in the lungs. We previously showed that the production of superoxide and hydrogen peroxide, i.e., the respiratory burst, is stimulated by adenine nucleotides (ADP > ATP) in rat AM through signaling pathways involving calcium and protein kinase C. Here, we further show that ADP induces a rapid increase in the tyrosine phosphorylation of several proteins that was reduced by the tyrosine kinase inhibitor genistein, which also inhibited the respiratory burst. Interestingly, ADP did not trigger the activation of the mitogen-activated protein kinases ERK1 and ERK2, or that of protein kinase B/AKT, a downstream target of the phosphatidylinositol 3-kinase (PI3K) pathway. This is in contrast to another stimulus of the respiratory burst, zymosan-activated serum (ZAS), which activates both the ERK and PI3K pathways. Thus, this study demonstrates that the receptor for ADP in rat AM is not coupled to the ERK and AKT pathways and, that neither the ERK pathway nor AKT is essential to induce the activation of the NAPDH oxidase by ADP in rat AM while tyrosine kinases appeared to be required. The rate and amount of hydrogen peroxide released by the ADP-stimulated respiratory burst was similar to that produced by ZAS stimulation. The absence of ERK activation after ADP stimulation therefore suggests that hydrogen peroxide is not sufficient to activate the ERK pathway in rat AM. Nonetheless, as hydrogen peroxide was necessary for ERK activation by ZAS, this indicates that, in contrast to ADP, ZAS stimulates a pathway that is targeted by hydrogen peroxide and leads to ERK activation.

  15. Vanillin suppresses Kupffer cell-related colloidal carbon-induced respiratory burst activity in isolated perfused rat liver: anti-inflammatory implications.

    PubMed

    Galgani, José E; Núñez, Bárbara; Videla, Luis A

    2012-12-01

    The inhibition of NADPH oxidase has become a potential therapeutic target for oxidative stress-related diseases. We investigated whether vanillin modifies hepatic O(2) consumption associated with Kupffer cell functioning. The influence of vanillin on Kupffer cell functioning was studied in isolated perfused rat liver by colloidal carbon (CC) infusion (0.5 mg ml(-1)), concomitantly with sinusoidal efflux of lactate dehydrogenase (LDH) as an organ viability parameter. CC infusion increased the rate of O(2) consumption of the liver above basal values, an effect that represents the respiratory burst activity of Kupffer cells. However, CC-dependent respiratory burst activity was suppressed by previous infusion of 2 mM vanillin. Vanillin did not affect the liver CC uptake rate and liver sinusoidal efflux of LDH efflux. These findings, elicited by vanillin, were reproduced by the well-established NADPH oxidase inhibitor apocynin. In conclusion, vanillin suppresses the respiratory burst activity of Kupffer cells as assessed in intact liver, which may be associated with the inhibition of macrophage NADPH oxidase activity. Such a finding may have relevance in conditions underlying Kupffer cell-dependent up-regulation of the expression and release of pro-inflammatory mediators by redox-dependent mechanisms.

  16. Resveratrol and curcumin reduce the respiratory burst of Chlamydia-primed THP-1 cells.

    PubMed

    Deby-Dupont, Ginette; Mouithys-Mickalad, Ange; Serteyn, Didier; Lamy, Maurice; Deby, Carol

    2005-07-22

    The intracellular bacterium Chlamydia pneumoniae is involved in the inflammation process of atherosclerosis. We previously demonstrated that C. pneumonia infected monocytes (THP-1 cells) responded to stimulation by an increased respiratory burst linked to an increased NADPH oxidase (NOX) activity. We now tested agents acting on the assembly of the NOX subunits or on protein kinase C, a trigger of NOX activity. Apocynin, resveratrol, rutin, quercetin, curcumin, and tocopherols were tested. The cells were pre-incubated with Chlamydia and the agent for 19 h, and then stimulated with phorbol myristate acetate. The NOX activity was monitored by measuring the hydrogen peroxide production. Resveratrol and curcumin (10(-4)-10(-6) M) were better inhibitors than apocynin. alpha-Tocopherol was inactive, and gamma-tocopherol inhibitor at 10(-4) M only. Quercetin was inactive, and rutin a moderate but significant inhibitor. The inhibition by resveratrol was increased by 10(-6) M rutin or quercetin. Resveratrol and curcumin thus appeared to be interesting for atherosclerosis treatment.

  17. Inhibitory effects of leaf extracts of Stachytarpheta jamaicensis (Verbenaceae) on the respiratory burst of rat macrophages.

    PubMed

    Alvarez, Ezequiel; Leiro, José Manuel; Rodríguez, Melita; Orallo, Francisco

    2004-06-01

    The anti-oxidant effects of ethyl acetate (EAcE) and n-hexane extracts (nHE) of dried leaves of Stachytarpheta jamaicensis Vahl. (Verbenaceae) on the reactive oxygen species (ROS) generating during the respiratory burst of rat peritoneal macrophages were investigated. Only EAcE, at concentrations between 0.4 and 40 microg/ml, inhibited the extracellular release of oxygen radicals by resident peritoneal macrophages stimulated with phorbol-12-myristate 13-acetate (PMA). At concentrations above 40 microg/ml, EAcE inhibited the production of nitric oxide (NO) in macrophages stimulated in vivo with sodium thioglycollate then in vitro with lipopolysaccharide (LPS) and gamma-interferon (IFN-gamma). nHE extracts at concentrations between 0.4 and 40 microg/ml did not scavenge (O-)2 generated enzymatically by hypoxanthine/xanthine oxidase (HX/XO) system, but EAcE at the same concentrations showed potent (O-)2-scavenging activity. At 40 microg/ml, EAcE also inhibited XO activity. These results suggest that the EAcE extract of S. jamaicensis may be a potential pharmaceutical value in treatment of immunopathological diseases related to oxidative stress.

  18. Respiratory burst in alveolar macrophages exposed to urban particles is not a predictor of cytotoxicity.

    PubMed

    Breznan, Dalibor; Goegan, Patrick; Chauhan, Vinita; Karthikeyan, Subramanian; Kumarathasan, Prem; Cakmak, Sabit; Nadeau, Denis; Brook, Jeffrey R; Vincent, Renaud

    2013-06-01

    We examined the utility of respiratory burst measurements in alveolar macrophages to assess adverse cellular changes following exposure to urban particles. Cells were obtained by bronchioalveolar lavage of Fisher 344 rats and exposed (0-100 μg/well) to urban particles (EHC-93, SRM-1648, SRM-1649, PM2.5), the soluble (EHC-93sol) and insoluble (EHC-93insol) fractions of EHC-93 (EHC-93tot), mineral particles (TiO(2), SiO(2)) and metal oxides (iron III oxide, iron II/III oxide, copper II oxide, nickel II oxide). The particle-induced respiratory burst was measured by chemiluminescence for 2h after the addition of particles. The cells were then stimulated with phorbol 12-myristate 13-acetate (PMA), yeast Zymosan fragments (Zymosan), or lipopolysaccharide plus interferon-gamma (LPS/IFN-γ) and the stimulant-induced respiratory burst was measured. Independently of the potential of particles to induce directly a respiratory burst, exposure to most particles attenuated the subsequent stimulant-induced burst. The notable exception was SiO(2), which produced a strong respiratory burst upon contact with the macrophages and enhanced the subsequent response to PMA or LPS/IFN-γ. Based on the degree of inhibition of the stimulant-dependent respiratory burst, particles were clustered into groups of high (SRM-1649, iron III oxide), intermediate (EHC-93tot, EHC-93insol, SRM-1648, VERP, iron II/III oxide, copper II oxide), and low (EHC-93sol, SiO(2), TiO2 and nickel II oxide) potency. Across these clusters, the potency of the particles to inhibit the stimulant-dependent respiratory burst showed poor correlation with cytotoxicity determined by XTT reduction assay.

  19. Phagocyte respiratory burst activates macrophage erythropoietin signalling to promote acute inflammation resolution

    PubMed Central

    Luo, Bangwei; Wang, Jinsong; Liu, Zongwei; Shen, Zigang; Shi, Rongchen; Liu, Yu-Qi; Liu, Yu; Jiang, Man; Wu, Yuzhang; Zhang, Zhiren

    2016-01-01

    Inflammation resolution is an active process, the failure of which causes uncontrolled inflammation which underlies many chronic diseases. Therefore, endogenous pathways that regulate inflammation resolution are fundamental and of wide interest. Here, we demonstrate that phagocyte respiratory burst-induced hypoxia activates macrophage erythropoietin signalling to promote acute inflammation resolution. This signalling is activated following acute but not chronic inflammation. Pharmacological or genetical inhibition of the respiratory burst suppresses hypoxia and macrophage erythropoietin signalling. Macrophage-specific erythropoietin receptor-deficient mice and chronic granulomatous disease (CGD) mice, which lack the capacity for respiratory burst, display impaired inflammation resolution, and exogenous erythropoietin enhances this resolution in WT and CGD mice. Mechanistically, erythropoietin increases macrophage engulfment of apoptotic neutrophils via PPARγ, promotes macrophage removal of debris and enhances macrophage migration to draining lymph nodes. Together, our results provide evidences of an endogenous pathway that regulates inflammation resolution, with important implications for treating inflammatory conditions. PMID:27397585

  20. Alternative oxidase in the branched mitochondrial respiratory network: an overview on structure, function, regulation, and role.

    PubMed

    Sluse, F E; Jarmuszkiewicz, W

    1998-06-01

    Plants and some other organisms including protists possess a complex branched respiratory network in their mitochondria. Some pathways of this network are not energy-conserving and allow sites of energy conservation to be bypassed, leading to a decrease of the energy yield in the cells. It is a challenge to understand the regulation of the partitioning of electrons between the various energy-dissipating and -conserving pathways. This review is focused on the oxidase side of the respiratory chain that presents a cyanide-resistant energy-dissipating alternative oxidase (AOX) besides the cytochrome pathway. The known structural properties of AOX are described including transmembrane topology, dimerization, and active sites. Regulation of the alternative oxidase activity is presented in detail because of its complexity. The alternative oxidase activity is dependent on substrate availability: total ubiquinone concentration and its redox state in the membrane and O2 concentration in the cell. The alternative oxidase activity can be long-term regulated (gene expression) or short-term (post-translational modification, allosteric activation) regulated. Electron distribution (partitioning) between the alternative and cytochrome pathways during steady-state respiration is a crucial measurement to quantitatively analyze the effects of the various levels of regulation of the alternative oxidase. Three approaches are described with their specific domain of application and limitations: kinetic approach, oxygen isotope differential discrimination, and ADP/O method (thermokinetic approach). Lastly, the role of the alternative oxidase in non-thermogenic tissues is discussed in relation to the energy metabolism balance of the cell (supply in reducing equivalents/demand in energy and carbon) and with harmful reactive oxygen species formation.

  1. Reconstitution of the membrane-bound, ubiquinone-dependent pyruvate oxidase respiratory chain of Escherichia coli with the cytochrome d terminal oxidase

    SciTech Connect

    Koland, J.G.; Miller, M.J.; Gennis, R.B.

    1984-01-31

    Pyruvate oxidase is a flavoprotein dehydrogenase located on the inner surface of the Escherichia coli cytoplasmic membrane and coupled to the E. coli aerobic respiratory chain. The role of quinones in the pyruvate oxidase system is investigated, and a minimal respiratory chain is described consisting of only two pure proteins plus ubiquinone 8 incorporated in phospholipid vesicles. The enzymes used in this reconstitution are the flavorprotein and the recently purified E. coli cytochrome d terminal oxidase. The catalytic velocity of the reconstituted liposome system is about 30% of that observed when the flavoprotein is reconstituted with E. coli membranes. It is also shown that electron transport from pyruvate to oxygen in the liposome system generates a transmembrane potential of at least 180 mV (negative inside), which is sensitive to the uncouplers carbonyl cyanide p-(trichloromethoxy)phenylhydrazone and valinomycin. A transmembrane potential is also generated by the oxidation of ubiquinol 1 by the terminal oxidase in the absence of the flavoprotein. It is concluded that: the flavoprotein can directly reduce ubiquinone 8 within the phospholipid bilayer; menaquinone 8 will not effectively substitute for ubiquinone 8 in this electron-transfer chain; and the cytochrome d terminal oxidase functions as a ubiquinol 8 oxidase and serves as a coupling site in the E. coli aerobic respiratory chain. These investigations suggest a relatively simple organization for the E. coli respiratory chain.

  2. Reconstitution of the membrane-bound, ubiquinone-dependent pyruvate oxidase respiratory chain of Escherichia coli with the cytochrome d terminal oxidase.

    PubMed

    Koland, J G; Miller, M J; Gennis, R B

    1984-01-31

    Pyruvate oxidase is a flavoprotein dehydrogenase located on the inner surface of the Escherichia coli cytoplasmic membrane and coupled to the E. coli aerobic respiratory chain. In this paper, the role of quinones in the pyruvate oxidase system is investigated, and a minimal respiratory chain is described consisting of only two pure proteins plus ubiquinone 8 incorporated in phospholipid vesicles. The enzymes used in this reconstitution are the flavoprotein and the recently purified E. coli cytochrome d terminal oxidase. The catalytic velocity of the reconstituted liposome system is about 30% of that observed when the flavoprotein is reconstituted with E. coli membranes. It is also shown that electron transport from pyruvate to oxygen in the liposome system generates a transmembrane potential of at least 180 mV (negative inside), which is sensitive to the uncouplers carbonyl cyanide p-(tri-chloromethoxy)phenylhydrazone and valinomycin. A trans-membrane potential is also generated by the oxidation of ubiquinol 1 by the terminal oxidase in the absence of the flavoprotein. It is concluded that (1) the flavoprotein can directly reduce ubiquinone 8 within the phospholipid bilayer, (2) menaquinone 8 will not effectively substitute for ubiquinone 8 in this electron-transfer chain, and (3) the cytochrome d terminal oxidase functions as a ubiquinol 8 oxidase and serves as a "coupling site" in the E. coli aerobic respiratory chain. These investigations suggest a relatively simple organization for the E. coli respiratory chain.

  3. Methods: implementation of in vitro and ex vivo phagocytosis and respiratory burst function assessments in safety testing.

    PubMed

    Freebern, Wendy J; Bigwarfe, Tammy J; Price, Karen D; Haggerty, Helen G

    2013-01-01

    Functional innate immune assessments, including phagocytosis and respiratory burst, are at the forefront of immunotoxicology evaluation in pre-clinical animal species. Although in the clinic and in academic science, phagocytosis, and respiratory burst assessments have been reported for over two decades, the implementation of phagocytosis and respiratory burst analyses in toxicology safety programs is just recently gaining publicity. Discussed herein are general methods, both microtiter plate-based and flow cytometric-based, for assessing phagocytosis and respiratory burst in pre-clinical species including mouse, rat, dog, and monkey. This methods-centric discussion includes a review of technologies and descriptions of method applications, with examples of results from analyses testing reported inhibitors (rottlerin, wortmannin, and SB203580) of phagocytosis and respiratory burst. Justification of implementation, strategic experimental design planning, and feasibility aspects of evaluating test article effects on phagocytosis and respiratory burst function are described within the context of a case study. The case study involves investigation of the effects of a small molecule p38 kinase inhibitor, BMS-582949, on phagocytosis and respiratory burst functions in rat and monkey neutrophils and monocytes in vitro, as well as ex vivo in these innate immune cells from monkeys administered BMS-582949 during a 1-week repeat dose investigative study. The results of the in vitro and ex vivo assessments demonstrated that BMS-582949 inhibited phagocytosis and respiratory burst. These findings correlated with incidences of opportunistic infections observed in rat and monkey toxicity studies.

  4. Eros is a novel transmembrane protein that controls the phagocyte respiratory burst and is essential for innate immunity

    PubMed Central

    Thomas, David C.; Clare, Simon; Sowerby, John M.; Juss, Jatinder K.; Goulding, David A.; van der Weyden, Louise; Prakash, Ananth; Harcourt, Katherine; Mukhopadhyay, Subhankar; Antrobus, Robin; Bateman, Alex

    2017-01-01

    The phagocyte respiratory burst is crucial for innate immunity. The transfer of electrons to oxygen is mediated by a membrane-bound heterodimer, comprising gp91phox and p22phox subunits. Deficiency of either subunit leads to severe immunodeficiency. We describe Eros (essential for reactive oxygen species), a protein encoded by the previously undefined mouse gene bc017643, and show that it is essential for host defense via the phagocyte NAPDH oxidase. Eros is required for expression of the NADPH oxidase components, gp91phox and p22phox. Consequently, Eros-deficient mice quickly succumb to infection. Eros also contributes to the formation of neutrophil extracellular traps (NETS) and impacts on the immune response to melanoma metastases. Eros is an ortholog of the plant protein Ycf4, which is necessary for expression of proteins of the photosynthetic photosystem 1 complex, itself also an NADPH oxio-reductase. We thus describe the key role of the previously uncharacterized protein Eros in host defense. PMID:28351984

  5. Eros is a novel transmembrane protein that controls the phagocyte respiratory burst and is essential for innate immunity.

    PubMed

    Thomas, David C; Clare, Simon; Sowerby, John M; Pardo, Mercedes; Juss, Jatinder K; Goulding, David A; van der Weyden, Louise; Storisteanu, Daniel; Prakash, Ananth; Espéli, Marion; Flint, Shaun; Lee, James C; Hoenderdos, Kim; Kane, Leanne; Harcourt, Katherine; Mukhopadhyay, Subhankar; Umrania, Yagnesh; Antrobus, Robin; Nathan, James A; Adams, David J; Bateman, Alex; Choudhary, Jyoti S; Lyons, Paul A; Condliffe, Alison M; Chilvers, Edwin R; Dougan, Gordon; Smith, Kenneth G C

    2017-04-03

    The phagocyte respiratory burst is crucial for innate immunity. The transfer of electrons to oxygen is mediated by a membrane-bound heterodimer, comprising gp91phox and p22phox subunits. Deficiency of either subunit leads to severe immunodeficiency. We describe Eros (essential for reactive oxygen species), a protein encoded by the previously undefined mouse gene bc017643, and show that it is essential for host defense via the phagocyte NAPDH oxidase. Eros is required for expression of the NADPH oxidase components, gp91phox and p22phox Consequently, Eros-deficient mice quickly succumb to infection. Eros also contributes to the formation of neutrophil extracellular traps (NETS) and impacts on the immune response to melanoma metastases. Eros is an ortholog of the plant protein Ycf4, which is necessary for expression of proteins of the photosynthetic photosystem 1 complex, itself also an NADPH oxio-reductase. We thus describe the key role of the previously uncharacterized protein Eros in host defense.

  6. Respiratory burst activity of intestinal macrophages in normal and inflammatory bowel disease.

    PubMed Central

    Mahida, Y R; Wu, K C; Jewell, D P

    1989-01-01

    Macrophages isolated from normal mucosa (greater than 5 cm from tumour) and inflamed mucosa (from patients with inflammatory bowel disease) of colon and ileum were studied for their ability to undergo a respiratory burst as assessed by reduction of nitroblue tetrazolium to formazan. Using phorbol myristate acetate (PMA) and opsonised zymosan as triggers, only a minority (median: 8% for zymosan and 9% for PMA) of macrophages isolated from normal colonic mucosa demonstrated release of oxygen radicals. In contrast, a significantly greater (median: 17% for zymosan and 45% for PMA) proportion of macrophages isolated from inflamed colonic mucosa were able to undergo respiratory burst. Studies with normal and inflamed ileum showed similar results. Stimulation of macrophages isolated from normal colon with interferon-gamma produced only a small increase in the proportion of cells showing release of oxygen radicals. We conclude that the respiratory burst capacity of majority of macrophages isolated from normal colon and ileum is downregulated and a greater proportion of macrophages isolated from inflamed colon and ileum are able to undergo a respiratory burst. Images Fig. 2 PMID:2511088

  7. Effect of magnetic resonance imaging on human respiratory burst of neutrophils.

    PubMed

    Heine, J; Scheinichen, D; Jaeger, K; Herzog, T; Sümpelmann, R; Leuwer, M

    1999-03-05

    It is known that low intensity magnetic fields increase superoxide anion production during the respiratory burst of rat peritoneal neutrophils in vitro. We investigated whether the high intensity magnetic fields (1.5 T) during magnetic resonance imaging can influence the human neutrophil function under in vivo conditions. Blood samples were obtained from 12 patients immediately before and after magnetic resonance imaging (mean time 27.6(+/-11.4 min)). The induced respiratory burst was investigated by the intracellular oxidative transformation of dihydrorhodamine 123 to the fluorescent dye rhodamine 123 via flow cytometry. The respiratory burst was induced either with phorbol 12-myristate 13-acetate, Escherichia coli, N-formyl-methionyl-leucylphenylalanine or priming with tumor necrosis factor followed by FMLP stimulation. There was no significant difference between the respiratory burst before and after magnetic resonance imaging, irrespective of the stimulating agent. Short time exposure to a high intensity magnetic field during magnetic resonance imaging seems not to influence the production of radical species in living neutrophils.

  8. Repeatability of flow cytometric and classical measurement of phagocytosis and respiratory burst in bovine polymorphonuclear leukocytes.

    PubMed

    Kampen, Annette H; Tollersrud, Tore; Larsen, Stig; Roth, James A; Frank, Dagmar E; Lund, Arve

    2004-01-01

    Five methods for measurement of phagocytosis and respiratory burst activity of bovine blood polymorphonuclear leukocytes (PMNs) were evaluated. Eight cows were repeatedly sampled over a two week period and parallel samples tested in all five assays to assess the repeatability and stability of the methods. In the flow cytometric phagocytosis assay, ingestion of fluorescein labeled bacteria was measured, and in the flow cytometric assay for respiratory burst, oxidation of a dye by reactive oxygen species was recorded. In the classical assays, bactericidal effect on opsonized, live bacteria was quantified by the conversion of an indicator substance, superoxide anion production was assayed by the reduction of cytochrome c, whereas myeloperoxidase activity was determined with a radioactive iodination assay. The results showed that the Phagotest, Bursttest, cytochrome c and iodination assays gave repeatable results when samples were run in the same setup on the same day. Although day-to-day variability was significant in all assays, the described methods comprise a panel of useful tests for the evaluation of phagocytosis and respiratory burst activity in bovine PMNs. The flow cytometric methods represent a convenient alternative to the classical methods for measurement of phagocytosis and respiratory burst in bovine blood PMNs.

  9. A purification procedure for the soluble cytochrome oxidase and some other respiratory proteins from Pseudomonas aeruginosa.

    PubMed

    Parr, S R; Barber, D; Greenwood, C

    1976-08-01

    The production of the soluble cytochrome oxidase/nitrite reductase in the bacterium Pseudomonas aeruginosa is favoured by anaerobic conditions and the presence of KNO3(20g/l) in the culture medium. Of three methods commonly used for the disruption of bacterial suspensions (ultrasonication, liquid-shear homogenization and glass-bead grinding), sonication proved the most efficient in releasing the Pseudomonas cytochrome oxidase. A polarographic assay of Pseudomonas cytochrome oxidase activity with sodium ascorbate as substrate and NNN'N'-tetramethyl-p-phenylenediamine dihydrochloride as electron mediator is described. A purification procedure was developed which can be used on the small scale (40-litre cultures) or the large scale (400-litre cultures) and provides high yields of three respiratory-chain proteins, Pseudomonas cytochrome oxidase, cytochrome c551 and azurin, in a pure state. A typical preparation of 250g of Ps.aeruginosa cell paste yielded 180mg of Pseudomonas cytochrome oxidase, 81 mg of Pseudomonas cytochrome c551 and 275mg of Pseudomonas azurin.

  10. Disruption of the CYTOCHROME C OXIDASE DEFICIENT1 gene leads to cytochrome c oxidase depletion and reorchestrated respiratory metabolism in Arabidopsis.

    PubMed

    Dahan, Jennifer; Tcherkez, Guillaume; Macherel, David; Benamar, Abdelilah; Belcram, Katia; Quadrado, Martine; Arnal, Nadège; Mireau, Hakim

    2014-12-01

    Cytochrome c oxidase is the last respiratory complex of the electron transfer chain in mitochondria and is responsible for transferring electrons to oxygen, the final acceptor, in the classical respiratory pathway. The essentiality of this step makes it that depletion in complex IV leads to lethality, thereby impeding studies on complex IV assembly and respiration plasticity in plants. Here, we characterized Arabidopsis (Arabidopsis thaliana) embryo-lethal mutant lines impaired in the expression of the CYTOCHROME C OXIDASE DEFICIENT1 (COD1) gene, which encodes a mitochondria-localized PentatricoPeptide Repeat protein. Although unable to germinate under usual conditions, cod1 homozygous embryos could be rescued from immature seeds and developed in vitro into slow-growing bush-like plantlets devoid of a root system. cod1 mutants were defective in C-to-U editing events in cytochrome oxidase subunit2 and NADH dehydrogenase subunit4 transcripts, encoding subunits of respiratory complex IV and I, respectively, and consequently lacked cytochrome c oxidase activity. We further show that respiratory oxygen consumption by cod1 plantlets is exclusively associated with alternative oxidase activity and that alternative NADH dehydrogenases are also up-regulated in these plants. The metabolomics pattern of cod1 mutants was also deeply altered, suggesting that alternative metabolic pathways compensated for the probable resulting restriction in NADH oxidation. Being the first complex IV-deficient mutants described in higher plants, cod1 lines should be instrumental to future studies on respiration homeostasis.

  11. Bacterial N-formyl Peptides Reduce PMA- and E.coli-induced Neutrophil Respiratory Burst in Term Neonates and Adults.

    PubMed

    Stålhammar, Maria E; Douhan Håkansson, Lena; Sindelar, Richard

    2017-02-15

    Neutrophil migration and respiratory burst is the prerequisite for efficient first line defense against invading microorganisms. However, migration and respiratory burst can be compromised in adults and especially in newborn infants, where sustained neutrophil accumulation, uncontrolled burst and reduced scavenging of ROS might cause inadvertent tissue damage due to uncontrolled inflammation. The aim of this study was to investigate the modulatory effect of the chemoattractants formyl-methionyl-leucyl-phenylalanine (fMLP) and IL-8 on respiratory burst in neutrophils from term newborn infants and adults. Whole blood from the umbilical cord of 17 healthy term newborn infants delivered by caesarean section and from 17 healthy adults as reference was preincubated with fMLP or IL-8 and stimulated with PMA or E.coli bacteria. Respiratory burst was quantified by flow cytometry analysis of dihydrorhodamine 123 fluorescence. fMLP reduced the PMA-induced respiratory burst of neutrophils from newborn infants and adults by 12% and 21% respectively (p<0.05). E.coli-induced burst was also reduced by fMLP in neutrophils from newborn infants (10%; p<0.01) and adults (6%; p<0.05). No such changes were observed with IL-8. Similar respiratory burst in response to single stimulus with PMA or E.coli were observed in both newborn infants and adults. fMLP reduced PMA- and E.coli-induced respiratory burst of neutrophils in whole blood from term newborn infants as well as in adults. The reduced respiratory burst by fMLP might be a mechanism to reduce the detrimental effects of uncontrolled inflammation during neutrophil migration. This article is protected by copyright. All rights reserved.

  12. Functional biomimetic models for the active site in the respiratory enzyme cytochrome c oxidase.

    PubMed

    Collman, James P; Decréau, Richard A

    2008-11-07

    A functional analog of the active site in the respiratory enzyme, cytochrome c oxidase (CcO) reproduces every feature in CcO's active site: a myoglobin-like heme (heme a3), a distal tridentate imidazole copper complex (Cu(B)), a phenol (Tyr244), and a proximal imidazole. When covalently attached to a liquid-crystalline SAM film on an Au electrode, this functional model continuously catalyzes the selective four-electron reduction of dioxygen at physiological potential and pH, under rate-limiting electron flux (as occurs in CcO).

  13. Phagocytosis and Respiratory Burst Activity in Lumpsucker (Cyclopterus lumpus L.) Leucocytes Analysed by Flow Cytometry

    PubMed Central

    Haugland, Gyri T.; Jakobsen, Ragnhild Aakre; Vestvik, Nils; Ulven, Kristian; Stokka, Lene; Wergeland, Heidrun I.

    2012-01-01

    In the present study, we have isolated leucocytes from peripheral blood, head kidney and spleen from lumpsucker (Cyclopterus lumpus L.), and performed functional studies like phagocytosis and respiratory burst, as well as morphological and cytochemical analyses. Different leucocytes were identified, such as lymphocytes, monocytes/macrophages and polymorphonuclear cells with bean shaped or bilobed nuclei. In addition, cells with similar morphology as described for dendritic cells in trout were abundant among the isolated leucocytes. Flow cytometry was successfully used for measuring phagocytosis and respiratory burst activity. The phagocytic capacity and ability were very high, and cells with different morphology in all three leucocyte preparations phagocytised beads rapidly. Due to lack of available cell markers, the identity of the phagocytic cells could not be determined. The potent non-specific phagocytosis was in accordance with a high number of cells positive for myeloperoxidase, an enzyme involved in oxygen-dependent killing mechanism present in phagocytic cells. Further, high respiratory burst activity was present in the leucocytes samples, verifying a potent oxygen- dependent degradation. At present, the specific antibody immune response could not be measured, as immunoglobulin or B-cells have not yet been isolated. Therefore, analyses of the specific immune response in this fish species await further clarification. The present study presents the first analyses of lumpsucker immunity and also the first within the order Scopaeniformes. PMID:23112870

  14. Phagocytosis and respiratory burst activity in lumpsucker (Cyclopterus lumpus L.) leucocytes analysed by flow cytometry.

    PubMed

    Haugland, Gyri T; Jakobsen, Ragnhild Aakre; Vestvik, Nils; Ulven, Kristian; Stokka, Lene; Wergeland, Heidrun I

    2012-01-01

    In the present study, we have isolated leucocytes from peripheral blood, head kidney and spleen from lumpsucker (Cyclopterus lumpus L.), and performed functional studies like phagocytosis and respiratory burst, as well as morphological and cytochemical analyses. Different leucocytes were identified, such as lymphocytes, monocytes/macrophages and polymorphonuclear cells with bean shaped or bilobed nuclei. In addition, cells with similar morphology as described for dendritic cells in trout were abundant among the isolated leucocytes. Flow cytometry was successfully used for measuring phagocytosis and respiratory burst activity. The phagocytic capacity and ability were very high, and cells with different morphology in all three leucocyte preparations phagocytised beads rapidly. Due to lack of available cell markers, the identity of the phagocytic cells could not be determined. The potent non-specific phagocytosis was in accordance with a high number of cells positive for myeloperoxidase, an enzyme involved in oxygen-dependent killing mechanism present in phagocytic cells. Further, high respiratory burst activity was present in the leucocytes samples, verifying a potent oxygen- dependent degradation. At present, the specific antibody immune response could not be measured, as immunoglobulin or B-cells have not yet been isolated. Therefore, analyses of the specific immune response in this fish species await further clarification. The present study presents the first analyses of lumpsucker immunity and also the first within the order Scopaeniformes.

  15. A proposed interplay between peroxidase, amine oxidase and lipoxygenase in the wounding-induced oxidative burst in Pisum sativum seedlings.

    PubMed

    Roach, Thomas; Colville, Louise; Beckett, Richard P; Minibayeva, Farida V; Havaux, Michel; Kranner, Ilse

    2015-04-01

    Plant surfaces form the barrier between a plant and its environment. Upon damage, the wound healing process begins immediately and is accompanied by a rapid production of extracellular reactive oxygen species (ROS), essential in deterring pathogens, signalling responses and cell wall restructuring. Although many enzymes produce extracellular ROS, it is unclear if ROS-producing enzymes act synergistically. We characterised the oxidative burst of superoxide (O2(·-)) and hydrogen peroxide (H2O2) that follows wounding in pea (Pisum sativum L.) seedlings. Rates of ROS production were manipulated by exogenous application of enzyme substrates and inhibitors. The results indicate significant roles for di-amine oxidases (DAO) and peroxidases (Prx) rather than NADPH oxidase. The burst of O2(·-) was strongly dependent on the presence of H2O2 produced by DAO. Potential substrates released from wounded seedlings included linoleic acid that, upon exogenous application, strongly stimulated catalase-sensitive O2(·-) production. Moreover, a 65kD plasma membrane (PM) guaiacol Prx was found in the secretome of wounded seedlings and showed dependence on linoleic acid for O2(·-) production. Lipoxygenases are suggested to modulate O2(·-) production by consuming polyunsaturated fatty acids in the apoplast. Overall, a O2(·-)-producing mechanism involving H2O2-derived from DAO, linoleic acid and a PM-associated Prx is proposed.

  16. Origin of the phagocytic respiratory burst and its role in gut epithelial phagocytosis in a basal chordate.

    PubMed

    Yang, Ping; Huang, Shengfeng; Yan, Xinyu; Huang, Guangrui; Dong, Xiangru; Zheng, Tingting; Yuan, Dongjuan; Wang, Ruihua; Li, Rui; Tan, Ying; Xu, Anlong

    2014-05-01

    The vertebrate phagocytic respiratory burst (PRB) is a highly specific and efficient mechanism for reactive oxygen species (ROS) production. This mechanism is mediated by NADPH oxidase 2 (NOX2) and used by vertebrate phagocytic leukocytes to destroy internalized microbes. Here we demonstrate the presence of the PRB in a basal chordate, the amphioxus Branchiostoma belcheri tsingtauense (bbt). We show that using the antioxidant NAC to scavenge the production of ROS significantly decreased the survival rates of infected amphioxus, indicating that ROS are indispensable for efficient antibacterial responses. Amphioxus NOX enzymes and cytosolic factors were found to colocalize in the epithelial cells of the gill, intestine, and hepatic cecum and could be upregulated after exposure to microbial pathogens. The ROS production in epithelial cell lysates could be reconstructed by supplementing recombinant cytosolic factors, including bbt-p47phox, bbt-p67phox, bbt-p47phox, and bbt-Rac; the restored ROS production could be inhibited by anti-bbt-NOX2 and anti-bbt-p67phox antibodies. We also reveal that the gut epithelial lining cells of the amphioxus are competent at bacterial phagocytosis, and there is evidence that the PRB machinery could participate in the initiation of this phagocytic process. In conclusion, we report the presence of the classical PRB machinery in nonvertebrates and provide the first evidence for the possible role of PRB in epithelial cell immunity and phagocytosis.

  17. Increased respiratory restriction during phosphate-limited growth in transgenic tobacco cells lacking alternative oxidase.

    PubMed

    Parsons, H L; Yip, J Y; Vanlerberghe, G C

    1999-12-01

    We found that mitochondrial alternative oxidase (AOX) protein and the capacity for CN-resistant respiration are dramatically increased in wild-type tobacco (Nicotiana tabacum) suspension-cultured cells in response to growth under P limitation, and antisense (AS8) tobacco cells unable to induce AOX under these conditions have altered growth and metabolism. Specifically, we found that the respiration of AS8 cells was restricted during P-limited growth, when the potential for severe adenylate control of respiration (at the level of C supply to the mitochondrion and/or at the level of oxidative phosphorylation) is high due to the low cellular levels of ADP and/or inorganic P. As a result of this respiratory restriction, AS8 cells had altered growth, morphology, cellular composition, and patterns of respiratory C flow to amino acid synthesis compared with wild-type cells with abundant AOX protein. Also, AS8 cells under P limitation displayed high in vivo rates of generation of active oxygen species compared with wild-type cells. This difference could be abolished by an uncoupler of mitochondrial oxidative phosphorylation. Our results suggest that induction of non-phosphorylating AOX respiration (like induction of adenylate and inorganic P-independent pathways in glycolysis) is an important plant metabolic adaptation to P limitation. By preventing severe respiratory restriction, AOX acts to prevent both redirections in C metabolism and the excessive generation of harmful active oxygen species in the mitochondrion.

  18. Distinguishing the Roles of Thylakoid Respiratory Terminal Oxidases in the Cyanobacterium Synechocystis sp. PCC 68031[OPEN

    PubMed Central

    Ermakova, Maria; Huokko, Tuomas; Richaud, Pierre; Bersanini, Luca; Howe, Christopher J.; Lea-Smith, David J.; Peltier, Gilles

    2016-01-01

    Various oxygen-utilizing electron sinks, including the soluble flavodiiron proteins (Flv1/3), and the membrane-localized respiratory terminal oxidases (RTOs), cytochrome c oxidase (Cox) and cytochrome bd quinol oxidase (Cyd), are present in the photosynthetic electron transfer chain of Synechocystis sp. PCC 6803. However, the role of individual RTOs and their relative importance compared with other electron sinks are poorly understood, particularly under light. Via membrane inlet mass spectrometry gas exchange, chlorophyll a fluorescence, P700 analysis, and inhibitor treatment of the wild type and various mutants deficient in RTOs, Flv1/3, and photosystem I, we investigated the contribution of these complexes to the alleviation of excess electrons in the photosynthetic chain. To our knowledge, for the first time, we demonstrated the activity of Cyd in oxygen uptake under light, although it was detected only upon inhibition of electron transfer at the cytochrome b6f site and in ∆flv1/3 under fluctuating light conditions, where linear electron transfer was drastically inhibited due to impaired photosystem I activity. Cox is mostly responsible for dark respiration and competes with P700 for electrons under high light. Only the ∆cox/cyd double mutant, but not single mutants, demonstrated a highly reduced plastoquinone pool in darkness and impaired gross oxygen evolution under light, indicating that thylakoid-based RTOs are able to compensate partially for each other. Thus, both electron sinks contribute to the alleviation of excess electrons under illumination: RTOs continue to function under light, operating on slower time ranges and on a limited scale, whereas Flv1/3 responds rapidly as a light-induced component and has greater capacity. PMID:27208274

  19. Effect of 2-hydroxyethyl-methacrylate (HEMA) on the phagocytic and respiratory burst activity of human neutrophils and monocytes.

    PubMed

    Andersson, Jennie; Dahlgren, Ulf I

    2008-08-01

    Neutrophils and monocytes/macrophages (MØ), found in oral mucosa and gingival sulcus, phagocytose and kill bacteria using products produced during a respiratory burst. 2-Hydroxyethyl-methacrylate (HEMA) is a major component released from resin glass ionomer and dental adhesives. Hence, in pulp and gingiva, phagocytes can come into contact with unpolymerized HEMA monomers. The aim of this study was to examine the effects of exposure to HEMA on neutrophil and monocyte bactericidal function. Blood collected from five female volunteers was exposed in vitro to HEMA for 2 h and then phagocytosis, respiratory burst, and cellular integrity were measured using flow cytometry. Respiratory burst was quantified by measuring fluorescent rhodamine 123 generated via oxidation of dihydrorhodamine 123. Cellular membrane integrity was evaluated by staining with propidium iodide. The respiratory burst activity of the neutrophils was significantly decreased by exposure to 7.5 and 15 mM HEMA. No significant effect of HEMA was seen on the number of granulocytes or monocytes capable of performing respiratory burst. Furthermore, there was no significant effect of HEMA on the phagocytic activity of the monocytes or the granulocytes. In conclusion, HEMA did not affect the phagocytosis activity of neutrophils; however, the ability of the cells to kill internalized prey was significantly reduced.

  20. Alternative oxidase: a respiratory electron transport chain pathway essential for maintaining photosynthetic performance during drought stress.

    PubMed

    Vanlerberghe, Greg C; Martyn, Greg D; Dahal, Keshav

    2016-07-01

    Photosynthesis and respiration are the hubs of energy metabolism in plants. Drought strongly perturbs photosynthesis as a result of both diffusive limitations resulting from stomatal closure, and in some cases biochemical limitations that are associated with a reduced abundance of key photosynthetic components. The effects of drought on respiration, particularly respiration in the light (RL ), are less understood. The plant mitochondrial electron transport chain includes a non-energy conserving terminal oxidase called alternative oxidase (AOX). Several studies have shown that drought increases AOX transcript, protein and maximum capacity. Here we review recent studies comparing wild-type (WT) tobacco to transgenic lines with altered AOX protein amount. Specifically during drought, RL was compromised in AOX knockdown plants and enhanced in AOX overexpression plants, compared with WT. Significantly, these differences in RL were accompanied by dramatic differences in photosynthetic performance. Knockdown of AOX increased the susceptibility of photosynthesis to drought-induced biochemical limitations, while overexpression of AOX delayed the development of such biochemical limitations, compared with WT. Overall, the results indicate that AOX is essential to maintaining RL during drought, and that this non-energy conserving respiration maintains photosynthesis during drought by promoting energy balance in the chloroplast. This review also outlines several areas for future research, including the possibility that enhancement of non-energy conserving respiratory electron sinks may be a useful biotechnological approach to increase plant performance during stress.

  1. Mitotane alters mitochondrial respiratory chain activity by inducing cytochrome c oxidase defect in human adrenocortical cells.

    PubMed

    Hescot, Ségolène; Slama, Abdelhamid; Lombès, Anne; Paci, Angelo; Remy, Hervé; Leboulleux, Sophie; Chadarevian, Rita; Trabado, Séverine; Amazit, Larbi; Young, Jacques; Baudin, Eric; Lombès, Marc

    2013-06-01

    Mitotane, 1,1-dichloro-2-(o-chlorophenyl)-2-(p-chlorophenyl)ethane is the most effective medical therapy for adrenocortical carcinoma, but its molecular mechanism of action remains poorly understood. Although mitotane is known to have mitochondrial (mt) effects, a direct link to mt dysfunction has never been established. We examined the functional consequences of mitotane exposure on proliferation, steroidogenesis, and mt respiratory chain, biogenesis and morphology, in two human adrenocortical cell lines, the steroid-secreting H295R line and the non-secreting SW13 line. Mitotane inhibited cell proliferation in a dose- and a time-dependent manner. At the concentration of 50 μM (14 mg/l), which corresponds to the threshold for therapeutic efficacy, mitotane drastically reduced cortisol and 17-hydroxyprogesterone secretions by 70%. This was accompanied by significant decreases in the expression of genes encoding mt proteins involved in steroidogenesis (STAR, CYP11B1, and CYP11B2). In both H295R and SW13 cells, 50 μM mitotane significantly inhibited (50%) the maximum velocity of the activity of the respiratory chain complex IV (cytochrome c oxidase (COX)). This effect was associated with a drastic reduction in steady-state levels of the whole COX complex as revealed by blue native PAGE and reduced mRNA expression of both mtDNA-encoded COX2 (MT-CO2) and nuclear DNA-encoded COX4 (COX4I1) subunits. In contrast, the activity and expression of respiratory chain complexes II and III were unaffected by mitotane treatment. Lastly, mitotane exposure enhanced mt biogenesis (increase in mtDNA content and PGC1α (PPARGC1A) expression) and triggered fragmentation of the mt network. Altogether, our results provide first evidence that mitotane induced a mt respiratory chain defect in human adrenocortical cells.

  2. Solubilization of the O2(-)-forming activity responsible for the respiratory burst in human neutrophils.

    PubMed

    Gabig, T G; Kipnes, R S; Babior, B M

    1978-10-10

    On exposure to suitable activating agents, neutrophils sharply alter their oxygen metabolism, showing large increases in oxygen uptake, O2 and H2O2 production, and glucose consumption via the hexose monophosphate shunt. These metabolic alterations, which together are designated the "respiratory burst," are due to the activation of a system which catalyzes the reaction: 2O2 + NADPH leads to 2O2(-) + NADP. This O2(-)-forming system is found in a particulate fraction isolated from neutrophils which had been activated with opsonized zymosan. When these particles were treated with detergent under suitable conditions, the O2(-)-forming activity was released in a form which passed through a membrane filter capable of retaining species of Mr greater than 3000,000. Soluble O2(-)-forming activity was obtained from normal activated neutrophils, but not from normal resting neutrophils or from activated neutrophils obtained from patients with chronic granulomatous disease, an inherited condition in which the respiratory burst is defective. O2(-)production by the soluble system required a reduced pyridine nucleotide as electron donor, and showed a quadratic dependence on the concentration of the solubilized preparation.

  3. Effects of oxygen tension and pH on the respiratory burst of human neutrophils.

    PubMed

    Gabig, T G; Bearman, S I; Babior, B M

    1979-06-01

    The respiratory burst of human neutrophils was measured under conditions of hypoxia and low pH. O2 -- production by neutrophils activated with opsonized zymosan fell slowly as the oxygen concentration declined to 1%, then dropped more sharply, reaching negligible levels at oxygen concentrations less than 0.25%. Production was half maximal at an oxygen concentration of 0.35% (equivalent to approximately 10-microM dissolved oxygen). O2- production by the cell-free O2- -forming system prepared from zymosan-activated neutrophils showed a similar dependence on oxygen concentration. A drop in pH caused decreases in both oxygen consumption and O2-- production by zymosan-treated neutrophils, values at PH 6.0 being 10%--20% of those observed at pH 7.5. Experiments with the cell-free O2-- -forming system suggested that this decline in respiratory burst activity at low pH was due to inefficient activation of the O2-- -forming enzyme under acidic conditions.

  4. Photosystem II and terminal respiratory oxidases: molecular machines operating in opposite directions.

    PubMed

    Siletsky, Sergey A; Borisov, Vitaliy B; Mamedov, Mahir D

    2017-03-01

    In the thylakoid membrane of green plants, cyanobacteria and algae, photosystem II (PSII) uses light energy to split water and generate molecular oxygen. In the opposite process of the biochemical transformation of dioxygen, in heterotrophs, the terminal respiratory oxidases (TRO) are at the end of the respiratory chain in mitochondria and in plasma membrane of many aerobic bacteria reducing dioxygen back to water. Despite the different sources of free energy (light or oxidation of the substrates), energy conversion by these enzymes is based on the spatial organization of enzymatic reactions in which the conversion of water to dioxygen (and vice versa) involves the transfer of protons and electrons in opposite directions across the membrane, which is accompanied by generation of proton-motive force. Similar and distinctive features in structure and function of these important energy-converting molecular machines are described. Information about many fascinating parallels between the mechanisms of TRO and PSII could be used in the artificial light-driven water-splitting process and elucidation of energy conversion mechanism in protein pumps.

  5. The cytochrome bd-I respiratory oxidase augments survival of multidrug-resistant Escherichia coli during infection

    PubMed Central

    Shepherd, Mark; Achard, Maud E. S.; Idris, Adi; Totsika, Makrina; Phan, Minh-Duy; Peters, Kate M.; Sarkar, Sohinee; Ribeiro, Cláudia A.; Holyoake, Louise V.; Ladakis, Dimitrios; Ulett, Glen C.; Sweet, Matthew J.; Poole, Robert K.; McEwan, Alastair G.; Schembri, Mark A.

    2016-01-01

    Nitric oxide (NO) is a toxic free radical produced by neutrophils and macrophages in response to infection. Uropathogenic Escherichia coli (UPEC) induces a variety of defence mechanisms in response to NO, including direct NO detoxification (Hmp, NorVW, NrfA), iron-sulphur cluster repair (YtfE), and the expression of the NO-tolerant cytochrome bd-I respiratory oxidase (CydAB). The current study quantifies the relative contribution of these systems to UPEC growth and survival during infection. Loss of the flavohemoglobin Hmp and cytochrome bd-I elicit the greatest sensitivity to NO-mediated growth inhibition, whereas all but the periplasmic nitrite reductase NrfA provide protection against neutrophil killing and promote survival within activated macrophages. Intriguingly, the cytochrome bd-I respiratory oxidase was the only system that augmented UPEC survival in a mouse model after 2 days, suggesting that maintaining aerobic respiration under conditions of nitrosative stress is a key factor for host colonisation. These findings suggest that while UPEC have acquired a host of specialized mechanisms to evade nitrosative stresses, the cytochrome bd-I respiratory oxidase is the main contributor to NO tolerance and host colonisation under microaerobic conditions. This respiratory complex is therefore of major importance for the accumulation of high bacterial loads during infection of the urinary tract. PMID:27767067

  6. What doesn't kill you makes you stronger: the anti-inflammatory effect of neutrophil respiratory burst.

    PubMed

    Borregaard, Niels

    2014-01-16

    In this issue of Immunity, Campbell et al. (2014) demonstrate that hypoxia caused by the respiratory burst of infiltrating neutrophils activates hypoxia inducible factor (HIF) in epithelial cells and protects the mucosa cells in an experimental model of inflammatory bowel disease.

  7. Strboh A homologue of NADPH oxidase regulates wound-induced oxidative burst and facilitates wound-healing in potato tubers.

    PubMed

    Kumar, G N Mohan; Iyer, Suresh; Knowles, N Richard

    2007-12-01

    During 30-months of storage at 4 degrees C, potato (Solanum tuberosum L.) tubers progressively lose the ability to produce superoxide in response to wounding, resist microbial infection, and develop a suberized wound periderm. Using differentially aged tubers, we demonstrate that Strboh A is responsible for the wound-induced oxidative burst in potato and aging attenuates its expression. In vivo superoxide production and NADPH oxidase (NOX) activity from 1-month-old tubers increased to a maximum 18-24 h after wounding and then decreased to barely detectable levels by 72 h. Wounding also induced a 68% increase in microsomal protein within 18 h. These wound-induced responses were lost over a 25- to 30-month storage period. Superoxide production and NOX activity were inhibited by diphenylene iodonium chloride, a specific inhibitor of NOX, which in turn effectively inhibited wound-healing and increased susceptibility to microbial infection and decay in 1-month-old tubers. Wound-induced superoxide production was also inhibited by EGTA-mediated destabilization of membranes. The ability to restore superoxide production to EGTA-treated tissue with Ca(+2) declined with advancing tuber age, likely a consequence of age-related changes in membrane architecture. Of the five homologues of NOX (Strboh A-D and F), wounding induced the expression of Strboh A in 6-month-old tubers but this response was absent in tubers stored for 25-30 months. Strboh A thus mediates the initial burst of superoxide in response to wounding of potato tubers; loss of its expression increases the susceptibility to microbial infection and contributes to the age-induced loss of wound-healing ability.

  8. Bursting Types and Bifurcation Analysis in the Pre-Bötzinger Complex Respiratory Rhythm Neuron

    NASA Astrophysics Data System (ADS)

    Wang, Jing; Lu, Bo; Liu, Shenquan; Jiang, Xiaofang

    Many types of neurons and excitable cells could intrinsically generate bursting activity, even in an isolated case, which plays a vital role in neuronal signaling and synaptic plasticity. In this paper, we have mainly investigated bursting types and corresponding bifurcations in the pre-Bötzinger complex respiratory rhythm neuron by using fast-slow dynamical analysis. The numerical simulation results have showed that for some appropriate parameters, the neuron model could exhibit four distinct types of fast-slow bursters. We also explored the bifurcation mechanisms related to these four types of bursters through the analysis of phase plane. Moreover, the first Lyapunov coefficient of the Hopf bifurcation, which can decide whether it is supercritical or subcritical, was calculated with the aid of MAPLE software. In addition, we analyzed the codimension-two bifurcation for equilibria of the whole system and gave a detailed theoretical derivation of the Bogdanov-Takens bifurcation. Finally, we obtained expressions for a fold bifurcation curve, a nondegenerate Hopf bifurcation curve, and a saddle homoclinic bifurcation curve near the Bogdanov-Takens bifurcation point.

  9. Evidence for a Key Role of Cytochrome bo3 Oxidase in Respiratory Energy Metabolism of Gluconobacter oxydans

    PubMed Central

    Richhardt, Janine; Luchterhand, Bettina; Büchs, Jochen

    2013-01-01

    The obligatory aerobic acetic acid bacterium Gluconobacter oxydans oxidizes a variety of substrates in the periplasm by membrane-bound dehydrogenases, which transfer the reducing equivalents to ubiquinone. Two quinol oxidases, cytochrome bo3 and cytochrome bd, then catalyze transfer of the electrons from ubiquinol to molecular oxygen. In this study, mutants lacking either of these terminal oxidases were characterized. Deletion of the cydAB genes for cytochrome bd had no obvious influence on growth, whereas the lack of the cyoBACD genes for cytochrome bo3 severely reduced the growth rate and the cell yield. Using a respiration activity monitoring system and adjusting different levels of oxygen availability, hints of a low-oxygen affinity of cytochrome bd oxidase were obtained, which were supported by measurements of oxygen consumption in a respirometer. The H+/O ratio of the ΔcyoBACD mutant with mannitol as the substrate was 0.56 ± 0.11 and more than 50% lower than that of the reference strain (1.26 ± 0.06) and the ΔcydAB mutant (1.31 ± 0.16), indicating that cytochrome bo3 oxidase is the main component for proton extrusion via the respiratory chain. Plasmid-based overexpression of cyoBACD led to increased growth rates and growth yields, both in the wild type and the ΔcyoBACD mutant, suggesting that cytochrome bo3 might be a rate-limiting factor of the respiratory chain. PMID:23852873

  10. Assembly of respiratory complexes I, III, and IV into NADH oxidase supercomplex stabilizes complex I in Paracoccus denitrificans.

    PubMed

    Stroh, Anke; Anderka, Oliver; Pfeiffer, Kathy; Yagi, Takao; Finel, Moshe; Ludwig, Bernd; Schägger, Hermann

    2004-02-06

    Stable supercomplexes of bacterial respiratory chain complexes III (ubiquinol:cytochrome c oxidoreductase) and IV (cytochrome c oxidase) have been isolated as early as 1985 (Berry, E. A., and Trumpower, B. L. (1985) J. Biol. Chem. 260, 2458-2467). However, these assemblies did not comprise complex I (NADH:ubiquinone oxidoreductase). Using the mild detergent digitonin for solubilization of Paracoccus denitrificans membranes we could isolate NADH oxidase, assembled from complexes I, III, and IV in a 1:4:4 stoichiometry. This is the first chromatographic isolation of a complete "respirasome." Inactivation of the gene for tightly bound cytochrome c552 did not prevent formation of this supercomplex, indicating that this electron carrier protein is not essential for structurally linking complexes III and IV. Complex I activity was also found in the membranes of mutant strains lacking complexes III or IV. However, no assembled complex I but only dissociated subunits were observed following the same protocols used for electrophoretic separation or chromatographic isolation of the supercomplex from the wild-type strain. This indicates that the P. denitrificans complex I is stabilized by assembly into the NADH oxidase supercomplex. In addition to substrate channeling, structural stabilization of a membrane protein complex thus appears as one of the major functions of respiratory chain supercomplexes.

  11. Standardization of the antibody-dependent respiratory burst assay with human neutrophils and Plasmodium falciparum malaria.

    PubMed

    Llewellyn, David; Miura, Kazutoyo; Fay, Michael P; Williams, Andrew R; Murungi, Linda M; Shi, Jianguo; Hodgson, Susanne H; Douglas, Alexander D; Osier, Faith H; Fairhurst, Rick M; Diakite, Mahamadou; Pleass, Richard J; Long, Carole A; Draper, Simon J

    2015-09-16

    The assessment of naturally-acquired and vaccine-induced immunity to blood-stage Plasmodium falciparum malaria is of long-standing interest. However, the field has suffered from a paucity of in vitro assays that reproducibly measure the anti-parasitic activity induced by antibodies in conjunction with immune cells. Here we optimize the antibody-dependent respiratory burst (ADRB) assay, which assesses the ability of antibodies to activate the release of reactive oxygen species from human neutrophils in response to P. falciparum blood-stage parasites. We focus particularly on assay parameters affecting serum preparation and concentration, and importantly assess reproducibility. Our standardized protocol involves testing each serum sample in singlicate with three independent neutrophil donors, and indexing responses against a standard positive control of pooled hyper-immune Kenyan sera. The protocol can be used to quickly screen large cohorts of samples from individuals enrolled in immuno-epidemiological studies or clinical vaccine trials, and requires only 6 μL of serum per sample. Using a cohort of 86 samples, we show that malaria-exposed individuals induce higher ADRB activity than malaria-naïve individuals. The development of the ADRB assay complements the use of cell-independent assays in blood-stage malaria, such as the assay of growth inhibitory activity, and provides an important standardized cell-based assay in the field.

  12. Priming by grepafloxacin on respiratory burst of human neutrophils: its possible mechanism.

    PubMed

    Niwa, Masayuki; Kanamori, Yutaka; Hotta, Koichi; Matsuno, Hiroyuki; Kozawa, Osamu; Fujimoto, Sadaki; Uematsu, Toshihiko

    2002-10-01

    Grepafloxacin is a broad-spectrum fluoroquinolone derivative that has good tissue penetration. We demonstrated that grepafloxacin showed a priming effect on neutrophil respiratory burst, triggered by either a chemotactic factor N-formyl-methionyl-leucyl-phenylalanine (fMLP) or leukotriene B4 (LTB4), but not by the phorbol ester phorbol 12-myristate 13-acetate (PMA). The priming effect of grepafloxacin on fMLP-stimulated superoxide generation by human neutrophils correlated with the penetration of grepafloxacin into cells. Removal of extracellular grepafloxacin did not inhibit the priming effect on fMLP-stimulated superoxide generation. Furthermore, grepafloxacin induced the translocation of p47-phox and p67-phox to the membrane fraction of neutrophils, whereas tyrosine phosphorylation was hardly observed in neutrophils exposed to grepafloxacin. The priming effect of grepafloxacin on superoxide generation from neutrophils was not inhibited by treatment with pertussis toxin, a protein-tyrosine kinase inhibitor (ST-638) or a protein kinase C inhibitor (calphostin C), or chelation of extracellular calcium. Grepafloxacin did not change the fMLP receptor-binding properties. Taken together, these findings suggest that grepafloxacin evokes a priming effect on neutrophil superoxide generation intracellularly through the translocation of p47-phox and even p67-phox protein to the membrane fractions. GTP binding protein, protein-tyrosine phosphorylation and protein kinase C activation are not involved in the priming effect.

  13. Peritoneal macrophages from patients with cirrhotic ascites show impaired phagocytosis and vigorous respiratory burst

    PubMed Central

    Ahmed, Abdel Motaal M.; Bomford, Adrian; Nouri-Aria, Kayhan T.; Davies, Ted; Smith, Roger; Williams, Roger

    2011-01-01

    Cirrhotic patients (CPs) are susceptible to spontaneous bacterial peritonitis (SBP). Aim of this study was to examine if this susceptibility was related to peritoneal macrophages' (PMs) altered host defence. Absorbance of phagocytosed particles by PMs from CPs was lower than that of control (31.88% vs. 77.2%). Particle opsonisation increased the absorbance to 41% in CPs' PMs, and this value remains lower than the control; 77.2%. Respiratory burst (RB) was expressed as fluorescence index values, and these were higher in PMs from CPs than in controls (82 vs. 41, 73 vs. 26 and 71 vs. 26). IFN-γ made no further increase of RB values in PMs from CPs. CD14 expression was also higher in CPs' PMs. IFN-γ significantly downregulated CD14 expression in both CPs' PMs and control. Reduced phagocytosis by predominantly CD14-positive PMs from CPs could be related to intense RB. Findings suggest altered host defence that could contribute to susceptibility to SBP. PMID:24371553

  14. Influence of Rhodococcus equi on the respiratory burst of resident alveolar macrophages from horses

    SciTech Connect

    Brumbaugh, G.W.

    1986-01-01

    Rhodococcus equi is the etiologic agent of a devastating pneumonia of sporadic incidence in foals. The purpose of this study was to evaluate the influence of R. equi on the superoxide anion production, measured spectrophotometrically as the reduction of cytochrome C, and hexose monophosphate shunt activity, measured by /sup 14/CO/sub 2/ liberation from /sup 14/C-1-D-glucose, of alveolar macrophages from horses. Alveolar macrophages were harvested from 6 anesthetized, healthy, light-breed, adult horses by bronchoalveolar lavage. Following a randomized complete block design, the suspension of cells was divided into aliquots of 10/sup 6/ viable alveolar macrophages which were exposed to 1, 10 or 100 g. of opsonized R. equi or opsonized zymosan A at 37 C for 2 hours. In this study the respiratory burst of equine alveolar macrophages was only evidenced by the hexose monophosphate shunt activity and superoxide anion was not coincidentally produced. Rhodococcus equi did not adversely affect that response. The insignificant superoxide anion production by the alveolar macrophages suggests that this may not be a significant oxygen metabolite in those cells.

  15. Flow cytometry analyses of phagocytic and respiratory burst activities and cytochemical characterization of leucocytes isolated from wrasse (Labrus bergylta A.).

    PubMed

    Haugland, Gyri T; Rønneseth, Anita; Wergeland, Heidrun I

    2014-07-01

    We have isolated leucocytes from peripheral blood (PBL), head kidney (HKL) and spleen (SL) of wrasse (Labrus bergylta A.) and studied the innate immune responses phagocytosis and respiratory burst using flow cytometry. Further, we have characterized the phenotypic properties of the leucocytes by cytochemical staining. We could differentiate between several subsets of leucocytes; lymphocytes, monocytes/macrophages, neutrophils, eosinophils, basophils and small leucocytes that might be precursor or immature cells. One striking observation was the eosinophils which were present among HKL, PBL and SL. The neutrophils had rounded, bean shaped or bi-lobed nuclei and resembled neutrophils in Atlantic cod (Gadus morhua L.) and lumpsucker (Cyclopterus lumpus L.), but were different from the polymorphonucleated neutrophils in Atlantic salmon (Salmo salar L.) and humans. Basophils were observed, but they were rare. Phagocytosis and respiratory burst activities were detected among different cell types. Highest phagocytic activity was observed among monocytes/macrophages and small leucocytes. Several different subtypes had ability to perform an oxygen-dependent degradation of microbes, measured as respiratory burst activity. Knowledge of the basic properties of wrasse's leucocytes and innate immunology can benefit further studies on its adaptive immune responses.

  16. Flow cytometry assays of respiratory burst in Atlantic salmon (Salmo salar L.) and in Atlantic cod (Gadus morhua L.) leucocytes.

    PubMed

    Kalgraff, Cathrine A K; Wergeland, Heidrun I; Pettersen, Eirin Fausa

    2011-09-01

    The oxidation of dihydrorhodamine 123 (DHR) to the fluorescent rhodamine 123 (RHO) was detected using flow cytometry. This assay for detection of respiratory burst activity was established in peripheral blood leucocytes (PBL) and head kidney leucocytes (HKL) of Atlantic salmon and Atlantic cod. The leucocytes were stimulated by phorbol 12-myristate 13-acetate (PMA). For cod cells 10 times lower concentration of PMA had to be used compared to salmon cells, as higher concentrations were toxic and resulted in considerable cell death. The cells found to be RHO-positive were monocytes/macrophages and neutrophils based on the scatter dot plots, but for salmon also some small cells were found to have high fluorescence intensity both in the flow cytometry analyses and by fluorescence microscopy of cytospin preparations. The nature of these cells is not known. For cod leucocytes, such cells were not obvious. The instrument settings are a bit more demanding for cod, as cod cells die more easily compared to salmon cells. In both assays the limit between negative and positive cells has to be carefully considered. The presented flow cytometry protocols for measurements of respiratory burst in salmon and cod leucocytes can be applied in various studies where respiratory burst functions are involved, such as to verify if it is activated or suppressed in connection with infections and immunostimulation.

  17. Immunomodulatory activity of diethylcarbamazine on humoral, cellular cytokine response and respiratory burst in BALB/c mice.

    PubMed

    Medina-De la Garza, Carlos E; Guerrero-Ramírez, Graciela; García-Hernández, Marisela; Castro-Corona, M Angeles; Torres-López, Ernesto; Brattig, Norbert W; Salinas-Carmona, Mario C

    2012-06-01

    Diethylcarbamazine (DEC) is an anthelmintic piperazine derivative drug with putative immunomodulating properties, including increased platelet and granulocyte adhesion to parasites and enhanced production of cytokines. To further analyse these properties in a well-established animal model, we evaluated the effect of DEC on antibody, cellular cytokine response and respiratory burst in BALB/c mice. Animals were challenged with a thymus-dependent (tetanus toxoid, (TT)) and with a thymus-independent (lipopolysaccharide, (LPS)) antigen and treated with DEC for seven days with two different doses (50 mg/day and 500 mg/day). Serum was assessed for antibody production at 0, 4, 7, 14, 21 and 28 days after stimulation and at 0, 24 and 48 h for IL-2, IFN-γ, IL-10 and IL-12 release. Respiratory burst of neutrophils and monocytes from peripheral blood was measured by flow cytometry. We found low-dose treatment with DEC enhanced cytokine production vs. TT and antibody production vs. LPS, whereas a higher dose enhanced significantly the respiratory burst of both polymorphonuclear leukocytes and monocytes, with a significant higher effect on the former. Our results suggest a stimulating, dose-dependent immunomodulatory effect of DEC with a higher effect on the phagocytic cells.

  18. Respiratory burst facilitates the digestion of Escherichia coli killed by polymorphonuclear leukocytes.

    PubMed Central

    Weiss, J; Kao, L; Victor, M; Elsbach, P

    1987-01-01

    We examined factors that may limit degradation of bacterial protein of Escherichia coli S15 killed by polymorphonuclear leukocytes (PMN). Both human and rabbit PMN degraded up to 40% of [14C]amino acid-labeled protein of ingested and killed E. coli in 2 h as determined by loss of acid-precipitable radioactivity. In contrast, equally bactericidal broken-PMN preparations or isolated granules degraded only about 10% of bacterial protein regardless of pH. To determine whether activation of the respiratory burst contributes to digestion, we compared degradation by intact PMN in room air and under N2. Depletion of O2 by N2 flushing had no effect on the bactericidal activity of either human or rabbit PMN but reduced degradation by approximately 50%. Protein degradation during phagocytosis was also reduced in the presence of cyanide or azide, inhibitors of myeloperoxidase (MPO). PMN of two patients with chronic granulomatous disease ingested and killed E. coli S15 as well as did normal PMN but degraded bacterial protein as did normal PMN incubated under N2. The low degradative activity of PMN disrupted by sonication could be raised to nearly the level of intact PMN incubated in room air by preincubation of the PMN with 10(-7) M formyl-methionyl-leucyl-phenylalanine (fMLP) before sonication and by pretreatment of E. coli with MPO. Depletion of O2 or chloride during these preincubations with formyl-methionyl-leucyl-phenylalanine respectively, virtually abolished and markedly diminished stimulation of bacterial protein degradation. We conclude that enhanced MPO-mediated O2 metabolism of intact PMN plays a role in the digestion of killed E. coli. PMID:3305366

  19. Francisella noatunensis subsp. noatunensis replicates within Atlantic cod (Gadus morhua L.) leucocytes and inhibits respiratory burst activity.

    PubMed

    Vestvik, Nils; Rønneseth, Anita; Kalgraff, Cathrine A K; Winther-Larsen, Hanne C; Wergeland, Heidrun I; Haugland, Gyri T

    2013-09-01

    Francisella noatunensis subsp. noatunensis, causing granulomatosis in cod, has been shown to reside within cod immune cells, mainly within monocytes and macrophages. In the present study, we analysed the ability of the bacterium to replicate within adherent cells isolated from head kidney by in vitro infection of leucocytes. Two different technical approaches for flow cytometry analyses were performed for detection of intracellular bacteria. The presence of the wild type was assessed after identification by intracellular binding of specific antibodies to the pathogen. The other way was to use green fluorescent protein (GFP) transformed bacterium for infection studies allowing direct measurements of fluorescence from infected cells. By both methods we found an increase in fluorescence in infected cells, verifying bacterial replication, both after 4 and 28 h post infection in leucocytes isolated from head kidney (HKL). The GFP transformed bacterium was similar to the wild type in growth and infectivity pattern, showing that it can be a valuable tool for further studies of infection routes and pathology. Further, F. noatunensis subsp. noatunensis was found to inhibit respiratory burst activity, a potent pathogen killing mechanism, in cod leucocytes, but not in such cells from salmon. Our findings may indicate that inhibition of respiratory burst during Francisella infection is a key to its intracellular existence. This strategy seems to be conserved through evolution as it is also observed during infections in higher vertebrates caused by bacteria within the Francisella genus. The results presented here, showing the intracellular existence of Francisella, its replication within leucocytes and the inhibitory effect on respiratory burst, strongly support that these factors contribute to disease and pathology in infected cod. The intracellular replication shown in the present study might contribute to explain the problems of obtaining protective vaccines against

  20. Superoxide produced by activated neutrophils efficiently reduces the tetrazolium salt, WST-1 to produce a soluble formazan: a simple colorimetric assay for measuring respiratory burst activation and for screening anti-inflammatory agents.

    PubMed

    Tan, A S; Berridge, M V

    2000-04-21

    Activation of the respiratory burst of granulocytes and macrophages by invading microorganisms is a key first line cellular defence against infection. Failure to generate this response leads to persistent life-threatening infection unless appropriate antibiotic treatment is given. The respiratory burst of neutrophils is usually measured spectrophotometrically by following ferricytochrome c reduction, and histologically by using the tetrazolium salt, nitroblue tetrazolium, which is reduced intracellularly to an insoluble formazan. In both assays, reduction is mediated by superoxide generated via NADPH oxidase. Because ferricytochrome c has a high molecular mass and high background absorbance at 550 nm, the assay lacks sensitivity and is not ideally suited to microplate measurement. We have circumvented these limitations by using the cell-impermeable, sulfonated tetrazolium salt, WST-1, which exhibits very low background absorbance and is efficiently reduced by superoxide to a stable water-soluble formazan with high molar absorptivity. This has permitted adaptation of the WST-1 assay to microplate format while retaining sensitivity. Reduction of WST-1 by activated human peripheral blood neutrophils correlated closely with ferricytochrome c reduction across a range of PMA concentrations and with time of activation by PMA and fMLP. Reduction of WST-1 was inhibited by 98% by superoxide dismutase (20 microg/ml) and by 88% by the NADPH oxidase inhibitor, diphenyleneiodinium (10 microM) but was resistant to catalase, azide and the NADH oxidase inhibitor, resiniferatoxin. WST-1 and ferricytochrome c reduction were also compared using xanthine/xanthine oxidase to generate superoxide. Under optimised assay conditions, both WST-1 and ferricytochrome c reduction were directly proportional to added xanthine. WST-1 generated approximately 2-fold greater increase in absorbance than ferricytochrome c at their respective wavelengths, and this translated into increased assay

  1. Alternative Oxidase: A Mitochondrial Respiratory Pathway to Maintain Metabolic and Signaling Homeostasis during Abiotic and Biotic Stress in Plants

    PubMed Central

    Vanlerberghe, Greg C.

    2013-01-01

    Alternative oxidase (AOX) is a non-energy conserving terminal oxidase in the plant mitochondrial electron transport chain. While respiratory carbon oxidation pathways, electron transport, and ATP turnover are tightly coupled processes, AOX provides a means to relax this coupling, thus providing a degree of metabolic homeostasis to carbon and energy metabolism. Beside their role in primary metabolism, plant mitochondria also act as “signaling organelles”, able to influence processes such as nuclear gene expression. AOX activity can control the level of potential mitochondrial signaling molecules such as superoxide, nitric oxide and important redox couples. In this way, AOX also provides a degree of signaling homeostasis to the organelle. Evidence suggests that AOX function in metabolic and signaling homeostasis is particularly important during stress. These include abiotic stresses such as low temperature, drought, and nutrient deficiency, as well as biotic stresses such as bacterial infection. This review provides an introduction to the genetic and biochemical control of AOX respiration, as well as providing generalized examples of how AOX activity can provide metabolic and signaling homeostasis. This review also examines abiotic and biotic stresses in which AOX respiration has been critically evaluated, and considers the overall role of AOX in growth and stress tolerance. PMID:23531539

  2. Alternative oxidase: a mitochondrial respiratory pathway to maintain metabolic and signaling homeostasis during abiotic and biotic stress in plants.

    PubMed

    Vanlerberghe, Greg C

    2013-03-26

    Alternative oxidase (AOX) is a non-energy conserving terminal oxidase in the plant mitochondrial electron transport chain. While respiratory carbon oxidation pathways, electron transport, and ATP turnover are tightly coupled processes, AOX provides a means to relax this coupling, thus providing a degree of metabolic homeostasis to carbon and energy metabolism. Beside their role in primary metabolism, plant mitochondria also act as "signaling organelles", able to influence processes such as nuclear gene expression. AOX activity can control the level of potential mitochondrial signaling molecules such as superoxide, nitric oxide and important redox couples. In this way, AOX also provides a degree of signaling homeostasis to the organelle. Evidence suggests that AOX function in metabolic and signaling homeostasis is particularly important during stress. These include abiotic stresses such as low temperature, drought, and nutrient deficiency, as well as biotic stresses such as bacterial infection. This review provides an introduction to the genetic and biochemical control of AOX respiration, as well as providing generalized examples of how AOX activity can provide metabolic and signaling homeostasis. This review also examines abiotic and biotic stresses in which AOX respiration has been critically evaluated, and considers the overall role of AOX in growth and stress tolerance.

  3. Source and role of diacylglycerol formed during phagocytosis of opsonized yeast particles and associated respiratory burst in human neutrophils

    SciTech Connect

    Della Bianca, V.; Grzeskowiak, M.; Lissandrini, D.; Rossi, F. )

    1991-06-28

    The results presented in this paper demonstrate that in human neutrophils phagocytosis of C3b/bi and IgG-opsonized yeast particles is associated with activation of phospholipase D and that this reaction is the main source of diglycerides. The demonstration is based upon the following findings: (1) the challenge of neutrophils with these opsonized particles was followed by a rapid formation of (3H)alkyl-phosphatidic acid (( 3H)alkyl-PA) and (3H)alkyl-diglyceride (( 3H)alkyl-DG) in cells labeled with (3H)alkyl-lyso-phosphatidylcholine; (2) in the presence of ethanol (3H)alkyl-phosphatidylethanol was formed, and accumulation of (3H)alkyl-PA and (3H)alkyl-DG was depressed; (3) propranolol, by inhibiting the dephosphorylation of (3H)alkyl-PA, completely inhibited the accumulation of (3H)alkyl-DG and depressed by about 75% the formation of diglyceride mass. Evidence is also presented that phagocytosis of C3b/bi and IgG-opsonized yeast particles and associated respiratory burst can take place independently of diglyceride formation and of the activity of this second messenger on protein kinase C. In fact: (a) propranolol while completely inhibited the formation of diglyceride mass did not modify either the phagocytosis or respiratory burst; (b) these two processes were insensitive to staurosporine.

  4. Intracellular shunting of O{sub 2}{sup −} contributes to charge compensation and preservation of neutrophil respiratory burst in the absence of voltage-gated proton channel activity

    SciTech Connect

    Decleva, Eva; Menegazzi, Renzo; Fasolo, Alba; Defendi, Federica

    2013-07-15

    Proton efflux via voltage-gated proton channels (Hv1) is considered to mediate the charge compensation necessary to preserve NADPH oxidase activity during the respiratory burst. Using the Hv1 inhibitor Zn{sup 2+}, we found that the PMA-induced respiratory burst of human neutrophils is inhibited when assessed as extracellular production of O{sub 2}{sup −} and H{sub 2}O{sub 2}, in accordance with literature studies, but, surprisingly, unaffected when measured as oxygen consumption or total (extracellular plus intracellular) H{sub 2}O{sub 2} production. Furthermore, we show that inhibiting Hv1 with Zn{sup 2+} results in an increased production of intracellular ROS. Similar results, i.e. decreased extracellular and increased intracellular ROS production, were obtained using a human granulocyte-like cell line with severely impaired Hv1 expression. Acidic extracellular pH, which dampens proton efflux, also augmented intracellular production of H{sub 2}O{sub 2}. Zinc caused an increase in the rate but not in the extent of depolarization and cytosolic acidification indicating that mechanisms other than proton efflux take part in charge compensation. Our results suggest a hitherto unpredicted mechanism of charge compensation whereby, in the absence of proton efflux, part of O{sub 2}{sup −} generated within gp91{sup phox} in the plasma membrane is shunted intracellularly down electrochemical gradient to dampen excessive depolarization. This would preserve NADPH oxidase activity under conditions such as the inflammatory exudate in which the acidic pH hinders charge compensation by proton efflux. Highlights: • Neutrophils’ respiratory burst is not inhibited by the H{sup +} channel inhibitor Zn{sup 2+}. • Intracellular production of O{sub 2}{sup −} and H{sub 2}O{sub 2} is increased in the presence of Zn{sup 2+}. • Intracellular H{sub 2}O{sub 2} production is increased in H{sup +} channels knock-down cells. • Zn{sup 2+} increases the rate but not the extent of

  5. Voltage Gated Proton Channels Find Their Dream Job Managing the Respiratory Burst in Phagocytes

    PubMed Central

    DeCoursey, Thomas E.

    2011-01-01

    The voltage gated proton channel bears surprising resemblance to the voltage-sensing domain (S1–S4) of other voltage gated ion channels, but is a dimer with two conduction pathways. The proton channel seems designed for efficient proton extrusion from cells. In phagocytes, it facilitates the production of reactive oxygen species by NADPH oxidase. PMID:20134026

  6. The mitochondrial alternative oxidase Aox1 is needed to cope with respiratory stress but dispensable for pathogenic development in Ustilago maydis.

    PubMed

    Cárdenas-Monroy, Christian A; Pohlmann, Thomas; Piñón-Zárate, Gabriela; Matus-Ortega, Genaro; Guerra, Guadalupe; Feldbrügge, Michael; Pardo, Juan Pablo

    2017-01-01

    The mitochondrial alternative oxidase is an important enzyme that allows respiratory activity and the functioning of the Krebs cycle upon disturbance of the respiration chain. It works as a security valve in transferring excessive electrons to oxygen, thereby preventing potential damage by the generation of harmful radicals. A clear biological function, besides the stress response, has so far convincingly only been shown for plants that use the alternative oxidase to generate heat to distribute volatiles. In fungi it was described that the alternative oxidase is needed for pathogenicity. Here, we investigate expression and function of the alternative oxidase at different stages of the life cycle of the corn pathogen Ustilago maydis (Aox1). Interestingly, expression of Aox1 is specifically induced during the stationary phase suggesting a role at high cell density when nutrients become limiting. Studying deletion strains as well as overexpressing strains revealed that Aox1 is dispensable for normal growth, for cell morphology, for response to temperature stress as well as for filamentous growth and plant pathogenicity. However, during conditions eliciting respiratory stress yeast-like growth as well as hyphal growth is strongly affected. We conclude that Aox1 is dispensable for the normal biology of the fungus but specifically needed to cope with respiratory stress.

  7. The mitochondrial alternative oxidase Aox1 is needed to cope with respiratory stress but dispensable for pathogenic development in Ustilago maydis

    PubMed Central

    Piñón-Zárate, Gabriela; Matus-Ortega, Genaro; Guerra, Guadalupe; Feldbrügge, Michael; Pardo, Juan Pablo

    2017-01-01

    The mitochondrial alternative oxidase is an important enzyme that allows respiratory activity and the functioning of the Krebs cycle upon disturbance of the respiration chain. It works as a security valve in transferring excessive electrons to oxygen, thereby preventing potential damage by the generation of harmful radicals. A clear biological function, besides the stress response, has so far convincingly only been shown for plants that use the alternative oxidase to generate heat to distribute volatiles. In fungi it was described that the alternative oxidase is needed for pathogenicity. Here, we investigate expression and function of the alternative oxidase at different stages of the life cycle of the corn pathogen Ustilago maydis (Aox1). Interestingly, expression of Aox1 is specifically induced during the stationary phase suggesting a role at high cell density when nutrients become limiting. Studying deletion strains as well as overexpressing strains revealed that Aox1 is dispensable for normal growth, for cell morphology, for response to temperature stress as well as for filamentous growth and plant pathogenicity. However, during conditions eliciting respiratory stress yeast-like growth as well as hyphal growth is strongly affected. We conclude that Aox1 is dispensable for the normal biology of the fungus but specifically needed to cope with respiratory stress. PMID:28273139

  8. Effects of raspberry fruit extracts and ellagic acid on respiratory burst in murine macrophages.

    PubMed

    Raudone, Lina; Bobinaite, Ramune; Janulis, Valdimaras; Viskelis, Pranas; Trumbeckaite, Sonata

    2014-06-01

    The mechanism of action of polyphenolic compounds is attributed to their antioxidant, anti-inflammatory, and anti-proliferative properties and their effects on subcellular signal transduction, cell cycle impairment and apoptosis. A raspberry (Rubus idaeus L.) fruit extract contains various antioxidant active compounds, particularly ellagic acid (EA); however the exact intracellular mechanism of their action is not fully understood. The aim of the study was to evaluate the antioxidant effect of raspberry extracts, and that of ellagic acid by assessment of the production of the reactive oxygen species (ROS) by murine macrophage J774 cells. Raspberry extracts and their active compound EA did not affect or had very minor effects on cell viability. No significant difference in the ROS generation in arachidonic acid stimulated macrophages was determined for raspberry extracts and EA whereas in the phorbol-12 myristate-13 acetate model ROS generation was significantly (p < 0.05) reduced. Our observation that raspberry pomace extracts in vitro reduce ROS production in a J774 macrophage culture suggests that raspberry extract and ellagic acid mediated antioxidant effects may be due to the regulation of NADPH oxidase activity.

  9. May the variable magnetic field and pulse red light induce synergy effects in respiratory burst of neutrophils in vitro?

    NASA Astrophysics Data System (ADS)

    Nawrocka-Bogusz, H.; Jaroszyk, F.

    2011-12-01

    We investigated the effect of the red light (R) (630 nm), magnetic field (MF) and magnetic field combined with the red light (MF+R) upon reactive oxygen species (ROS) production by neutrophils in vitro. The object of the research was hydrogen peroxide (H2O2) formation during neutrophils respiratory burst or within steady-state. Blood from healthy volunteers was used for the purpose of the study. Flow cytometry method, using transformation of DCFH-DA (2'7'-dichlorofluorescin diacetate) to the fluorescent DCF (2'7'-dichlorofluorescin), was used for estimation of hydrogen peroxide production. The variable magnetic field of ELF range of the mean induction equals 26.7(μT), the red light at the energy density of 1.17(J/cm2) and their combination were applied for 30 minutes each. The fundamental frequency of pulses was 180÷ 195 Hz. A statistically significant decrease of H2O2 production by neutrophils was observed. The level of the decrease was in the range of 10-30% and was dependent on the kind of applied physical factors and whether neutrophils were stimulated or not. The observation showed that the variable magnetic field combined with red light do not induce the synergy effect.

  10. Factors influencing in vitro respiratory burst assays with head kidney leucocytes from rainbow trout, Oncorhynchus mykiss (Walbaum).

    PubMed

    Chettri, J K; Holten-Andersen, L; Buchmann, K

    2010-07-01

    Abstract Head kidney leucocytes are central elements in a number of in vivo and in vitro assays elucidating innate and adaptive immune mechanisms in teleosts following stimulation with various antigens. These systems are sensitive to several factors affecting the outcome of the assays. The present work describes the importance of temperature, cell concentration, exposure time and immune-modulatory molecules on the respiratory burst activity (RBA) of rainbow trout head kidney leucocytes in vitro. Some variation in RBA was observed among individual fish. However, use of cells pooled from four individuals produced satisfactory results following exposure to phorbol 12-myristate 13-acetate, zymosan and beta-glucan. Temperature was shown to have a significant effect on production of reactive radicals as illustrated by a high activity in cells maintained at 15-20 degrees C and a reduced activity at temperature extremes (1, 4 and 30 degrees C). Highest activity was found at a cell concentration of 1 x 10(7) cells mL(-1). Reactivity showed a clear decline when cells were exposed for more than 4 h. Moreover, incubation of cells with inhibitory substances viz., DiMePE2, cortisol and superoxide dismutase decreased the RBA. It is concluded that several biotic and abiotic factors should be taken into account when conducting RBA assays with head kidney leucocytes for elucidation of rainbow trout immune responses.

  11. Diet supplementation of Pediococcus pentosaceus in cobia (Rachycentron canadum) enhances growth rate, respiratory burst and resistance against photobacteriosis.

    PubMed

    Xing, Chen-Fu; Hu, Hung-Hsi; Huang, Jian-Bin; Fang, Han-Chun; Kai, Yu-Hsuan; Wu, Yu-Chi; Chi, Shau-Chi

    2013-10-01

    Cobia (Rachycentron canadum) is an economically important fish species for aquaculture in tropical and sub-tropical areas. Cobia aquaculture industry has severely damaged due to photobacteriosis caused by Photobacterium damselae subsp. piscicida (Pdp), especially in Taiwan. Antibiotics and vaccines have been applied to control Pdp infection, but the efficacy has been inconsistent. One species of lactic acid bacteria, Pediococcus pentosaceus strain 4012 (LAB 4012), was isolated from the intestine of adult cobia, and its culture supernatant can effectively inhibit Pdp growth in vitro. The acidic pH derived from metabolic acids in LAB culture supernatant was demonstrated to be an important factor for the suppression. After a 2-week feeding of LAB 4012, the growth rate of the fed cobia was 12% higher than that of the non-fed group, and the relative percentage of survival (RPS) of the fed cobia was found to be 74.4 in Pdp immersion challenge. In addition, the respiratory burst (RB) of peripheral blood leukocytes (PBL) in the LAB 4012-fed group was significantly higher than that of the non-fed group. Although feeding LAB 4012 did not improve specific antibody response in cobia after immunization with Pdp vaccine, it still significantly raised the survival rate by 22% over that of the non-fed group after Pdp immersion challenge. Judging by the quick induction of high protection against Pdp infection and promotion of growth in larvae, LAB 4012 was considered to be a viable probiotic for cobia aquaculture.

  12. The effects of oral consumption of selenium nanoparticles on chemotactic and respiratory burst activities of neutrophils in comparison with sodium selenite in sheep.

    PubMed

    Kojouri, Gholam Ali; Sadeghian, Sirous; Mohebbi, Abdonnaser; Mokhber Dezfouli, Mohammad Reza

    2012-05-01

    The present study was designed to compare the effects of nano-selenium and of sodium selenite on the chemotactic and respiratory burst activities of neutrophils in sheep. Fifteen sheep were randomly divided into three groups. Groups 1 and 2 received selenium nanoparticles (1 mg/kg) or sodium selenite (1 mg/kg) orally, respectively, for ten consecutive days, and the third group was considered as the control. To determine the chemotactic and respiratory burst activities of the neutrophils, the leading front assay and the NBT test were used on heparinized blood samples that were collected at different intervals (days 0, 10th, 20th, and 30th). The results obtained showed that the chemotactic activities in groups 1 and 2 increased significantly on the 10th, 20th, and 30th day, compared to day 0, and on the 20th day in comparison with the 10th day, while in group 2, there was a significant decrease on the 30th day compared to the 20th day. The chemotactic activities in group 1 were significantly higher than in group 2 on the 10th day and in the control group on the 10th, 20th, and 30th day, but the chemotactic activities in group 2 were significantly higher than those in the control group only on the 20th day. On the 30th day into the experiment, the respiratory bursts in groups 1 and 2 were significantly stronger in comparison with those at day 0. Overall, nano-selenium increased the chemotactic and respiratory burst activities more significantly than sodium selenite, which is suggestive of a stronger stimulatory effect of the Se nanoparticles on intracellular activities.

  13. Crystal structure of the membrane-exposed domain from a respiratory quinol oxidase complex with an engineered dinuclear copper center.

    PubMed

    Wilmanns, M; Lappalainen, P; Kelly, M; Sauer-Eriksson, E; Saraste, M

    1995-12-19

    Cytochrome oxidase is a membrane protein complex that catalyzes reduction of molecular oxygen to water and utilizes the free energy of this reaction to generate a transmembrane proton gradient during respiration. The electron entry site in subunit II is a mixed-valence dinuclear copper center in enzymes that oxidize cytochrome c. This center has been lost during the evolution of the quinoloxidizing branch of cytochrome oxidases but can be restored by engineering. Herein we describe the crystal structures of the periplasmic fragment from the wild-type subunit II (CyoA) of Escherichia coli quinol oxidase at 2.5-A resolution and of the mutant with the engineered dinuclear copper center (purple CyoA) at 2.3-A resolution. CyoA is folded as an 11-stranded mostly antiparallel beta-sandwich followed by three alpha-helices. The dinuclear copper center is located at the loops between strands beta 5-beta 6 and beta 9-beta 10. The two coppers are at a 2.5-A distance and symmetrically coordinated to the main ligands that are two bridging cysteines and two terminal histidines. The residues that are distinct in cytochrome c and quinol oxidases are around the dinuclear copper center. Structural comparison suggests a common ancestry for subunit II of cytochrome oxidase and blue copper-binding proteins.

  14. Spontaneous oscillatory burst activity in the piriform-amygdala region and its relation to in vitro respiratory activity in newborn rats.

    PubMed

    Onimaru, H; Homma, I

    2007-01-05

    The amygdala is important for the formation of emotions that are affected by olfactory information. The piriform cortex is involved in information processing related to olfaction. To investigate functional interactions between the piriform cortex and amygdala and their relation to medullary respiratory activity, we developed a novel in vitro preparation including the limbic system, brainstem, and spinal cord of newborn rats. With the use of optical and electrophysiologic recordings, we analyzed spontaneous neuronal activity in the piriform-amygdala complex in limbic-brainstem-spinal cord preparations from 0- to 1-day-old rats. For optical recordings, the preparation was stained with a voltage-sensitive dye, and inspiratory activity was monitored from the fourth cervical (C4) ventral root. Spontaneous oscillatory burst activity (up to 10/min) was detected from the rostral cut surface of limbic and para-limbic regions including the piriform cortex and amygdala. The burst activity initially appeared in the piriform cortex and then propagated to the amygdala. We averaged the imaging data in the limbic area with the use of C4 inspiratory activity as a trigger signal. The results suggest functional coupling of the rhythmic burst activity in the piriform-amygdala complex to medullary inspiratory activity, which was confirmed electrophysiologically by cross-correlation analysis of these signals. This rhythmic burst activity may be involved in the development of neuronal circuits that process information related to olfaction, emotion, and respiration.

  15. Comparative study of β-glucan induced respiratory burst measured by nitroblue tetrazolium assay and real-time luminol-enhanced chemiluminescence assay in common carp (Cyprinus carpio L.).

    PubMed

    Vera-Jimenez, N I; Pietretti, D; Wiegertjes, G F; Nielsen, M E

    2013-05-01

    The respiratory burst is an important feature of the immune system. The increase in cellular oxygen uptake that marks the initiation of the respiratory burst is followed by the production of reactive oxygen species (ROS) such as superoxide anion and hydrogen peroxide which plays a role in the clearance of pathogens and tissue regeneration processes. Therefore, the respiratory burst and associated ROS constitute important indicators of fish health status. This paper compares two methods for quantitation of ROS produced during the respiratory burst in common carp: the widely used, single-point measurement based on the intracellular reduction of nitroblue tetrazolium (NBT) and a real-time luminol-enhanced assay based on the detection of native chemiluminescence. Both assays allowed for detection of dose-dependent changes in magnitude of the respiratory burst response induced by β-glucans in head kidney cells of carp. However, whereas the NBT assay was shown to detect the production of only superoxide anions, the real-time luminol-enhanced assay could detect the production of both superoxide anions and hydrogen peroxide. Only the chemiluminescence assay could reliably record the production of ROS on a real-time scale at frequent and continual time intervals for time course experiments, providing more detailed information on the respiratory burst response. The real-time chemiluminescence assay was used to measure respiratory burst activity in macrophage and neutrophilic granulocyte-enriched head kidney cell fractions and total head kidney cell suspensions and proved to be a fast, reliable, automated multiwell microplate assay to quantitate fish health status modulated by β-glucans.

  16. Inhibitory effect of lactone fractions and individual components from three species of the Achillea millefolium complex of Bulgarian origin on the human neutrophils respiratory burst activity.

    PubMed

    Choudhary, Muhammad Iqbal; Jalil, Saima; Todorova, M; Trendafilova, A; Mikhova, B; Duddeck, H; Atta-ur-Rahman

    2007-09-01

    Achillea species are widely used in folk medicine for treatment of inflammatory diseases. The inhibitory effect on the human neutrophils respiratory burst activity of total extracts, their fractions and some main constituents of the flower heads from Achillea asplenifolia, A. collina and A. distans belonging to A. millefolium complex of Bulgarian origin, were tested by the modified method of Tan and Berridge. Seven from the investigated fractions showed activity similar or higher than that of indomethacine and might be evaluated as nonsteroidal anti-inflammatory agents.

  17. Study of the effects of salicylic acid on soybean mitochondrial lipids and respiratory properties using the alternative oxidase as a stress-reporter protein.

    PubMed

    Matos, Ana Rita; Mendes, Ana Teresa; Scotti-Campos, Paula; Arrabaça, João Daniel

    2009-12-01

    Biotic and abiotic stresses can lead to modifications in the lipid composition of cell membranes. Although mitochondria appear to be implicated in stress responses, little is known about the membrane lipid changes that occur in these organelles in plants. Besides cytochrome c oxidase, plant mitochondria have an alternative oxidase (AOX) that accepts electrons directly from ubiquinol, dissipating energy as heat. AOX upregulation occurs under a variety of stresses and its induction by salicylic acid (SA) has been observed in different plant species. AOX was also suggested to be used as a functional marker for cell reprogramming under stress. In the present study, we have used etiolated soybean (Glycine max (L.) Merr. cv Cresir) seedlings to study the effects of SA treatment on the lipid composition and the respiratory properties of hypocotyl mitochondria. AOX expression was studied in detail, as a reporter protein, to evaluate whether modifications in mitochondrial energy metabolism were occurring. In mitochondria extracted from SA-treated seedlings, AOX capacity and protein contents increased. Both AOX1 and AOX2b transcripts accumulated in response to SA, but with different kinetics. A reduction in external NADH oxidation capacity was observed, whereas succinate respiration remained unchanged. The phospholipid composition of mitochondria remained similar in control and SA-treated plants, but a reduction in the relative amount of linolenic acid was observed in phosphatidylcholine, phosphatidylethanolamine and cardiolipin. The possible causes of the fatty acid modifications observed, and the implications for mitochondrial metabolism are discussed.

  18. Disparate effects of interferon-gamma and tumor necrosis factor-alpha on early neutrophil respiratory burst and fungicidal responses to Candida albicans hyphae in vitro.

    PubMed Central

    Diamond, R D; Lyman, C A; Wysong, D R

    1991-01-01

    We examined effects of priming with recombinant human interferon-gamma (IFN) or tumor necrosis factor-alpha (TNF) on neutrophil responses to Candida albicans hyphae. Both cytokines increased early superoxide generation after hyphal stimulation. The more pronounced effects of TNF were accompanied by an augmented surface membrane depolarization rate and were insensitive to both pertussis toxin and calcium ion chelation, but were negated by concomitant incubation with puromycin or cycloheximide during priming. IFN augmented hyphal killing despite its only minor enhancement of early respiratory burst responses, but TNF reduced neutrophil fungicidal activity to nearly 40% below those by unprimed control cells even though it enhanced early superoxide responses more dramatically. Though TNF-primed neutrophils killed hyphae at normal initial rates, IFN-primed or even unprimed cells manifested more fungicidal sustained activity. These disparate consequences of cytokine priming on hyphal destruction were paralleled by differences in late generation of potentially candidacidal oxidants, hydrogen peroxide, and hypochlorous acid. IFN added during priming failed to correct TNF-associated functional defects in neutrophil anti-Candida responses. Thus, augmentation of early respiratory burst responses to oxidant-sensitive organisms need not necessarily reflect concomitant salutary effects on microbicidal activity. Images PMID:1846880

  19. Specific localization of the respiratory alternative oxidase in meristematic and xylematic tissues from developing soybean roots and hypocotyls.

    PubMed Central

    Hilal, M; Castagnaro, A; Moreno, H; Massa, E M

    1997-01-01

    We used tissue printing and specific immunostaining to examine the localization of the alternative oxidase (AOX) protein in correlation with measurements of AOX capacity. Selected root and hypocotyl regions were analyzed during the first 14 d of growth. It is shown that AOX protein is localized in the apical meristem and in developing xylem. The temporal pattern of expression is coincident with the evolution of AOX capacity. Data suggest that AOX expression is linked to xylem differentiation. Since heat is a major product of the alternative pathway, we speculate that thermogenesis is implicated in morphogenesis. PMID:9414560

  20. Pityriarubins, novel highly selective inhibitors of respiratory burst from cultures of the yeast Malassezia furfur: comparison with the bisindolylmaleimide arcyriarubin A.

    PubMed

    Krämer, Hans-Joachim; Kessler, Dino; Hipler, Ute-Christina; Irlinger, Bernhard; Hort, Wiebke; Bödeker, Rolf-Hasso; Steglich, Wolfgang; Mayser, Peter

    2005-12-01

    Pityriasis versicolor is the most common skin mycosis in humans worldwide. Yeasts of the genus Malassezia, particularly M. furfur, a saprophyte occurring widely on human skin, are generally regarded as the causative agents. M. furfur is able to convert tryptophan into a variety of indole alkaloids, some of them showing biological properties that correlate well with certain clinical features of pityriasis versicolor. This suggests a possible role for these compounds in the pathophysiology of the disease. We here report that the novel pityriarubins A, B and C, isolated from cultures of the yeast, inhibit respiratory burst in human neutrophils, activated by various agents, in a highly selective, unexpected manner. The release of 5-lipoxygenase products after challenge of neutrophils with the calcium ionophore A23187 is also inhibited in a dose-dependent manner. These activities reflect the close structural relationship of pityriarubins to bisindolylmaleimides, which have recently gained great interest as protein kinase inhibitors.

  1. NADPH Oxidase-Dependent NLRP3 Inflammasome Activation and its Important Role in Lung Fibrosis by Multiwalled Carbon Nanotubes.

    PubMed

    Sun, Bingbing; Wang, Xiang; Ji, Zhaoxia; Wang, Meiying; Liao, Yu-Pei; Chang, Chong Hyun; Li, Ruibin; Zhang, Haiyuan; Nel, André E; Xia, Tian

    2015-05-06

    The purpose of this paper is to elucidate the key role of NADPH oxidase in NLRP3 inflammasome activation and generation of pulmonary fibrosis by multi-walled carbon nanotubes (MWCNTs). Although it is known that oxidative stress plays a role in pulmonary fibrosis by single-walled CNTs, the role of specific sources of reactive oxygen species, including NADPH oxidase, in inflammasome activation remains to be clarified. In this study, three long aspect ratio (LAR) materials (MWCNTs, single-walled carbon nanotubes, and silver nanowires) are used to compare with spherical carbon black and silver nanoparticles for their ability to trigger oxygen burst activity and NLRP3 assembly. All LAR materials but not spherical nanoparticles induce robust NADPH oxidase activation and respiratory burst activity in THP-1 cells, which are blunted in p22(phox) -deficient cells. The NADPH oxidase is directly involved in lysosomal damage by LAR materials, as demonstrated by decreased cathepsin B release and IL-1β production in p22(phox) -deficient cells. Reduced respiratory burst activity and inflammasome activation are also observed in bone marrow-derived macrophages from p47(phox) -deficient mice. Moreover, p47(phox) -deficient mice have reduced IL-1β production and lung collagen deposition in response to MWCNTs. Lung fibrosis is also suppressed by N-acetyl-cysteine in wild-type animals exposed to MWCNTs.

  2. Peroxisomal polyamine oxidase and NADPH-oxidase cross-talk for ROS homeostasis which affects respiration rate in Arabidopsis thaliana

    PubMed Central

    Andronis, Efthimios A.; Moschou, Panagiotis N.; Toumi, Imene; Roubelakis-Angelakis, Kalliopi A.

    2014-01-01

    Homeostasis of reactive oxygen species (ROS) in the intracellular compartments is of critical importance as ROS have been linked with nearly all cellular processes and more importantly with diseases and aging. PAs are nitrogenous molecules with an evolutionary conserved role in the regulation of metabolic and energetic status of cells. Recent evidence also suggests that polyamines (PA) are major regulators of ROS homeostasis. In Arabidopsis the backconversion of the PAs spermidine (Spd) and spermine to putrescine and Spd, respectively, is catalyzed by two peroxisomal PA oxidases (AtPAO). However, the physiological role of this pathway remains largely elusive. Here we explore the role of peroxisomal PA backconversion and in particular that catalyzed by the highly expressed AtPAO3 in the regulation of ROS homeostasis and mitochondrial respiratory burst. Exogenous PAs exert an NADPH-oxidase dependent stimulation of oxygen consumption, with Spd exerting the strongest effect. This increase is attenuated by treatment with the NADPH-oxidase blocker diphenyleneiodonium iodide (DPI). Loss-of-function of AtPAO3 gene results to increased NADPH-oxidase-dependent production of superoxide anions (O2•− ), but not H2O2, which activate the mitochondrial alternative oxidase pathway (AOX). On the contrary, overexpression of AtPAO3 results to an increased but balanced production of both H2O2 and O2•− . These results suggest that the ratio of O2•− /H2O2 regulates respiratory chain in mitochondria, with PA-dependent production of O2•− by NADPH-oxidase tilting the balance of electron transfer chain in favor of the AOX pathway. In addition, AtPAO3 seems to be an important component in the regulating module of ROS homeostasis, while a conserved role for PA backconversion and ROS across kingdoms is discussed. PMID:24765099

  3. RhoA/ROCK downregulates FPR2-mediated NADPH oxidase activation in mouse bone marrow granulocytes.

    PubMed

    Filina, Julia V; Gabdoulkhakova, Aida G; Safronova, Valentina G

    2014-10-01

    Polymorphonuclear neutrophils (PMNs) express the high and low affinity receptors to formylated peptides (mFPR1 and mFPR2 in mice, accordingly). RhoA/ROCK (Rho activated kinase) pathway is crucial for cell motility and oxidase activity regulated via FPRs. There are contradictory data on RhoA-mediated regulation of NADPH oxidase activity in phagocytes. We have shown divergent Rho GTPases signaling via mFPR1 and mFPR2 to NADPH oxidase in PMNs from inflammatory site. The present study was aimed to find out the role of RhoA/ROCK in the respiratory burst activated via mFPR1 and mFPR2 in the bone marrow PMNs. Different kinetics of RhoA activation were detected with 0.1μM fMLF and 1μM WKYMVM operating via mFPR1 and mFPR2, accordingly. RhoA was translocated in fMLF-activated cells towards the cell center and juxtamembrane space versus uniform allocation in the resting cells. Specific inhibition of RhoA by CT04, Rho inhibitor I, weakly depressed the respiratory burst induced via mFPR1, but significantly increased the one induced via mFPR2. Inhibition of ROCK, the main effector of RhoA, by Y27632 led to the same effect on the respiratory burst. Regulation of mFPR2-induced respiratory response by ROCK was impossible under the cytoskeleton disruption by cytochalasin D, whereas it persisted in the case of mFPR1 activation. Thus we suggest RhoA to be one of the regulatory and signal transduction components in the respiratory burst through FPRs in the mouse bone marrow PMNs. Both mFPR1 and mFPR2 binding with a ligand trigger the activation of RhoA. FPR1 signaling through RhoA/ROCK increases NADPH-oxidase activity. But in FPR2 action RhoA/ROCK together with cytoskeleton-linked systems down-regulates NADPH-oxidase. This mechanism could restrain the reactive oxygen species dependent damage of own tissues during the chemotaxis of PMNs and in the resting cells.

  4. Effects of heat stress on respiratory burst, oxidative damage and SERPINH1 (HSP47) mRNA expression in rainbow trout Oncorhynchus mykiss.

    PubMed

    Wang, Yanni; Liu, Zhe; Li, Zhen; Shi, Haina; Kang, Yujun; Wang, Jianfu; Huang, Jinqiang; Jiang, Li

    2016-04-01

    For rainbow trout Oncorhynchus mykiss, high temperature is a major abiotic stress that limits its growth and productivity. In this study, spleen macrophage respiratory burst (RB), serum superoxide dismutase (SOD), serum malondialdehyde (MDA) and mRNA expression of the SERPINH1 (HSP47) gene in different tissues (liver, spleen, head kidney and heart) were measured in unstressed (18 °C) and heat-stressed (25 °C) fish. Spleen macrophage RB activity, serum SOD activity and MDA content all increased significantly (P < 0.05) during heat shock, and peaked at 8, 12 and 4 h, respectively. SERPINH1 mRNA expression responded in a time- and tissue-specific manner to heat stress, which was mainly reflected in the significant up-regulation in all tissues (P < 0.05) and greater expression in the liver than the other tissues (P < 0.05). During the heat-shock recovery period, the MDA content returned to the unstressed level. These results indicate that heat shock causes cell injury, induces oxidative damage and promotes SERPINH1 mRNA expression, which plays an important protective function during heat stress in O. mykiss. In practice, close attention should be given to temperature changes in O. mykiss production to reduce the effects of high temperature.

  5. Expression of alternative oxidase in tomato

    SciTech Connect

    Kakefuda, M.; McIntosh, L. )

    1990-05-01

    Tomato fruit ripening is characterized by an increase in ethylene biosynthesis, a burst in respiration (i.e. the climacteric), fruit softening and pigmentation. As whole tomatoes ripened from mature green to red, there was an increase in the alternative oxidase capacity. Aging pink tomato slices for 24 and 48 hrs also showed an increase of alternative oxidase and cytochrome oxidase capacities. Monoclonal antibodies prepared to the Sauromatum guttatum alternative oxidase were used to follow the appearance of alternative oxidase in tomato fruits. There is a corresponding increase in a 36kDa protein with an increase in alternative oxidase capacity. Effects of ethylene and norbornadiene on alternative oxidase capacity were also studied. We are using an alternative oxidase cDNA clone from potato to study the expression of mRNA in ripening and wounded tomatoes to determine if the gene is transcriptionally regulated.

  6. Increase of dietary vitamin C improves haemocyte respiratory burst response and growth of juvenile grass shrimp, Penaeus monodon, fed with high dietary copper.

    PubMed

    Lee, Min-Hsien; Shiau, Shi-Yen

    2003-04-01

    Effects of dietary vitamin C (l-ascorbyl-2-monophosphate-Mg, C2MP-Mg) on growth, tissue copper (Cu) accumulation, and haemocyte superoxide anion production of juvenile grass shrimp, Penaeus monodon, fed with either adequate or high (8 x adequate) dietary Cu were studied. Three experimental diets were used: basal diet supplemented with adequate levels of both C2MP-Mg (40 mg kg diet(-1)) and Cu (20mg kg diet(-1)) (NC-NCu); basal diet supplemented with adequate C2MP-Mg and high Cu (8 x adequate) (NC-HCu); and basal diet supplemented with high C2MP-Mg (5 x adequate) and high Cu (HC-HCu). These were each fed to triplicate groups of shrimp (mean initial weight: 0.29+/-0.01 g) for 8 weeks. Highest (P< 0.01) weight gain, feed efficiency (FE) and protein efficiency ratio (PER) were observed in shrimp fed NC-NCu diet, intermediate in shrimp fed HC-HCu diet, and lowest in shrimp fed NC-HCu diet. Cu concentrations in hepatopancreas, muscle and haemolymph were highest in shrimp fed NC-HCu diet, followed by shrimp fed HC-HCu diet, and lowest for shrimp fed NC-NCu diet. Survival, total haemocyte count (THC) and intracellular superoxide anion (O-2) production were higher in shrimp fed NC-NCu diet than shrimp fed NC-HCu diet, whereas hepatosomatic index (HSI) was higher in shrimp fed NC-HCu diet than shrimp fed NC-NCu diet. However, all these parameters were similar in shrimp fed NC-NCu diet and shrimp fed HC-HCu diet. These data suggest that increase of dietary vitamin C improved haemocyte respiratory burst response and growth and prevented tissue Cu accumulation in P. monodon fed with high dietary Cu.

  7. Effects of various extremely low frequency magnetic fields on the free radical processes, natural antioxidant system and respiratory burst system activities in the heart and liver tissues.

    PubMed

    Canseven, Ayse Gulnihal; Coskun, Sule; Seyhan, Nesrin

    2008-10-01

    Magnetic fields (MFs) can affect biological systems by increasing the release of free radicals that are able to alter cell defense systems and breakdown tissue homeostasis. In the present study, the effects of extremely low frequency (ELF) electromagnetic fields (EMF) were investigated on free radical levels, natural antioxidant systems and respiratory burst system activities in heart and liver tissues of guinea pigs exposed to 50 Hz MFs of 1, 2 and 3 mT for 4 h/day and 8 h/day for 5 days by measuring malondialdehyde (MDA), nitric oxide (NO), glutathione (GSH) levels and myeloperoxidase (MPO) activity. A total of sixty-two male guinea pigs, 10-12 weeks old were studied in seven groups as control and exposure groups: Group I (control), II (1 mT, 4 h/day), III (1 mT, 8 h/day), IV (2 mT, 4 h/day), V (2 mT, 8 h/day), VI (3 mT, 4 h/day), and VII (3 mT, 8 h/day). Controls were kept under the same conditions without any exposure to MF. MDA levels increased in liver in groups II and IV, but decreased in group VII for both liver and heart tissues. NOx levels declined in heart in groups II and III and in liver in groups III, V, and VI, but increased in liver in group VII. GSH levels increased in heart in groups II, IV, V, and in liver in groups V and VI and VI, but decreased in groups II and IV in liver. MPO activity decreased in liver in groups III, IV, VI and VII with respect to controls and in heart tissues in groups II, III and IV; however, there was a significant increase MPO activity in heart in group VII. From the results, it can be concluded that the intensity and exposure duration of MFs are among the effective conditions on the formation of free radicals and behaviour of antioxidant enzymes.

  8. The causes of reduced proton-pumping efficiency in type B and C respiratory heme-copper oxidases, and in some mutated variants of type A.

    PubMed

    Rauhamäki, Virve; Wikström, Mårten

    2014-07-01

    The heme-copper oxidases may be divided into three categories, A, B, and C, which include cytochrome c and quinol-oxidising enzymes. All three types are known to be proton pumps and are found in prokaryotes, whereas eukaryotes only contain A-type cytochrome c oxidase in their inner mitochondrial membrane. However, the bacterial B- and C-type enzymes have often been reported to pump protons with an H(+)/e(-) ratio of only one half of the unit stoichiometry in the A-type enzyme. We will show here that these observations are likely to be the result of difficulties with the measuring technique together with a higher sensitivity of the B- and C-type enzymes to the protonmotive force that opposes pumping. We find that under optimal conditions the H(+)/e(-) ratio is close to unity in all the three heme-copper oxidase subfamilies. A higher tendency for proton leak in the B- and C-type enzymes may result from less efficient gating of a proton pump mechanism that we suggest evolved before the so-called D-channel of proton transfer. There is also a discrepancy between results using whole bacterial cells vs. phospholipid vesicles inlaid with oxidase with respect to the observed proton pumping after modification of the D-channel residue asparagine-139 (Rhodobacter sphaeroides numbering) to aspartate in A-type cytochrome c oxidase. This discrepancy might also be explained by a higher sensitivity of proton pumping to protonmotive force in the mutated variant. This article is part of a Special Issue entitled: 18th European Bioenergetic Conference.

  9. Calcium-dependent protein kinases regulate the production of reactive oxygen species by potato NADPH oxidase.

    PubMed

    Kobayashi, Michie; Ohura, Ikuko; Kawakita, Kazuhito; Yokota, Naohiko; Fujiwara, Masayuki; Shimamoto, Ko; Doke, Noriyuki; Yoshioka, Hirofumi

    2007-03-01

    Reactive oxygen species (ROS) are implicated in plant innate immunity. NADPH oxidase (RBOH; for Respiratory Burst Oxidase Homolog) plays a central role in the oxidative burst, and EF-hand motifs in the N terminus of this protein suggest possible regulation by Ca(2+). However, regulatory mechanisms are largely unknown. We identified Ser-82 and Ser-97 in the N terminus of potato (Solanum tuberosum) St RBOHB as potential phosphorylation sites. An anti-phosphopeptide antibody (pSer82) indicated that Ser-82 was phosphorylated by pathogen signals in planta. We cloned two potato calcium-dependent protein kinases, St CDPK4 and St CDPK5, and mass spectrometry analyses showed that these CDPKs phosphorylated only Ser-82 and Ser-97 in the N terminus of St RBOHB in a calcium-dependent manner. Ectopic expression of the constitutively active mutant of St CDPK5, St CDPK5VK, provoked ROS production in Nicotiana benthamiana leaves. The CDPK-mediated ROS production was disrupted by knockdown of Nb RBOHB in N. benthamiana. The loss of function was complemented by heterologous expression of wild-type potato St RBOHB but not by a mutant (S82A/S97A). Furthermore, the heterologous expression of St CDPK5VK phosphorylated Ser-82 of St RBOHB in N. benthamiana. These results suggest that St CDPK5 induces the phosphorylation of St RBOHB and regulates the oxidative burst.

  10. Legume NADPH Oxidases Have Crucial Roles at Different Stages of Nodulation

    PubMed Central

    Montiel, Jesús; Arthikala, Manoj-Kumar; Cárdenas, Luis; Quinto, Carmen

    2016-01-01

    Plant NADPH oxidases, formerly known as respiratory burst oxidase homologues (RBOHs), are plasma membrane enzymes dedicated to reactive oxygen species (ROS) production. These oxidases are implicated in a wide variety of processes, ranging from tissue and organ growth and development to signaling pathways in response to abiotic and biotic stimuli. Research on the roles of RBOHs in the plant’s response to biotic stresses has mainly focused on plant-pathogen interactions; nonetheless, recent findings have shown that these oxidases are also involved in the legume-rhizobia symbiosis. The legume-rhizobia symbiosis leads to the formation of the root nodule, where rhizobia reduce atmospheric nitrogen to ammonia. A complex signaling and developmental pathway in the legume root hair and root facilitate rhizobial entrance and nodule organogenesis, respectively. Interestingly, several reports demonstrate that RBOH-mediated ROS production displays versatile roles at different stages of nodulation. The evidence collected to date indicates that ROS act as signaling molecules that regulate rhizobial invasion and also function in nodule senescence. This review summarizes discoveries that support the key and versatile roles of various RBOH members in the legume-rhizobia symbiosis. PMID:27213330

  11. Purification and characterization of a lipid thiobis ester from human neutrophil cytosol that reversibly deactivates the O2- -generating NADPH oxidase.

    PubMed

    Eklund, E A; Gabig, T G

    1990-05-25

    Intact neutrophils possess a cellular mechanism that efficiently deactivates the microbicidal O2-generating NADPH oxidase during the respiratory burst (Akard, L. P., English, D., and Gabig, T. G. (1988) Blood 72, 322-327). The present studies directed at identifying the molecular mechanism(s) involved in NADPH oxidase deactivation showed that a heat- and trypsin-insensitive species in the cytosolic fraction from normal unstimulated neutrophils was capable of deactivating the membrane-associated NADPH oxidase isolated from opsonized zymosan- or phorbol 12-myristate 13-acetate-stimulated neutrophils. This cytosolic species also deactivated the cell-free-activated oxidase. Deactivation by this cytosolic species occurred in the absence of NADPH-dependent catalytic turnover and was reversible, since NADPH oxidase activity could be subsequently reactivated in the cell-free system. The sedimentable particulate fraction from unstimulated neutrophils did not demonstrate deactivator activity. Deactivator activity was demonstrated in the neutral lipid fraction of neutrophil cytosol extracted with chloroform:methanol. Following complete purification of cytosolic deactivator activity by thin layer chromatography and reversed phase high performance liquid chromatography, the deactivator species was shown to be a lipid thiobis ester compound by mass spectroscopy. Cellular metabolism of this compound in human neutrophils may reveal a unique mechanism for enzymatic control of the NADPH oxidase system and thereby play an important role in regulation of the inflammatory response.

  12. Correction of Aberrant NADPH Oxidase Activity in Blood-Derived Mononuclear Cells from Type II Diabetes Mellitus Patients by a Naturally Fermented Papaya Preparation

    PubMed Central

    Dickerson, Ryan; Deshpande, Bhakthi; Gnyawali, Urmila; Lynch, Debbie; Gordillo, Gayle M.; Schuster, Dara; Osei, Kwame

    2012-01-01

    Abstract Supplementation of standardized fermented papaya preparation (FPP) to adult diabetic mice improves dermal wound healing outcomes. Peripheral blood mononuclear cells (PBMC) from type II diabetes mellitus (T2DM) patients elicit a compromised respiratory burst activity resulting in increased risk of infections for the diabetic patients. Aims: The objectives of the current study were to determine the effect of FPP supplementation on human diabetic PBMC respiratory burst activity and to understand underlying mechanisms of such action of FPP. Results: When stimulated with phorbol 12-myristate 13-acetate, the production of reactive oxygen species by T2DM PBMC was markedly compromised compared to that of the PBMC from non-DM donors. FPP treated ex vivo improved respiratory burst outcomes in T2DM PBMC. FPP treatment significantly increased phosphorylation of the p47phox subunit of NADPH oxidase. In addition, the protein and mRNA expression of Rac2 was potently upregulated after FPP supplemention. The proximal human Rac2 gene promoter is G–C rich and contains consensus binding sites for Sp1 and AP-1. While FPP had no significant effect on the AP-1 DNA binding activity, the Sp1 DNA binding activity was significantly upregulated in PBMC after treatment of the cells with FPP. Innovation: This work provided first evidence that compromised respiratory burst performance of T2DM PBMC may be corrected by a nutritional supplement. Conclusion: FPP can correct respiratory burst performance of T2DM PBMC via an Sp-1-dependant pathway. Studies testing the outcome of FPP supplementation in diabetic patients are warranted. Antioxid. Redox Signal. 17, 485–491. PMID:22369197

  13. The Respiratory Burst and Electrolyte Leakage Induced by Sulfhydryl Blockers in Egeria densa Leaves Are Associated with H2O2 Production and Are Dependent on Ca2+ Influx1

    PubMed Central

    Marrè, Maria Teresa; Amicucci, Enrica; Zingarelli, Luisa; Albergoni, Francesco; Marrè, Erasmo

    1998-01-01

    In leaves of Egeria densa Planchon, N-ethylmaleimide (NEM) and other sulfhydryl-binding reagents induce a temporary increase in nonmitochondrial respiration (ΔQO2) that is inhibited by diphenylene iodonium and quinacrine, two known inhibitors of the plasma membrane NADPH oxidase, and are associated with a relevant increase in electrolyte leakage (M. Bellando, S. Sacco, F. Albergoni, P. Rocco, M.T. Marré [1997] Bot Acta 110: 388–394). In this paper we report data indicating further analogies between the oxidative burst induced by sulfhydryl blockers in E. densa and that induced by pathogen-derived elicitors in animal and plant cells: (a) NEM- and Ag+-induced ΔQO2 was associated with H2O2 production and both effects depended on the presence of external Ca2+; (b) Ca2+ influx was markedly increased by treatment with NEM; (c) the Ca2+ channel blocker LaCl3 inhibited ΔQO2, electrolyte release, and membrane depolarization induced by the sulfhydryl reagents; and (d) LaCl3 also inhibited electrolyte leakage induced by the direct infiltration of the leaves with H2O2. These results suggest a model in which the interaction of sulfhydryl blockers with sulfhydryl groups of cell components would primarily induce an increase in the Ca2+ cytosolic concentration, followed by membrane depolarization and activation of a plasma membrane NADPH oxidase. This latter effect, producing active oxygen species, might further influence plasma membrane permeability, leading to the massive release of electrolytes from the tissue. PMID:9847112

  14. The respiratory burst and electrolyte leakage induced by sulfhydryl blockers in egeria densa leaves are associated with H2O2 production and are dependent on Ca2+ influx

    PubMed

    Marre; Amicucci; Zingarelli; Albergoni; Marre

    1998-12-01

    In leaves of Egeria densa Planchon, N-ethylmaleimide (NEM) and other sulfhydryl-binding reagents induce a temporary increase in nonmitochondrial respiration (DeltaQO2) that is inhibited by diphenylene iodonium and quinacrine, two known inhibitors of the plasma membrane NADPH oxidase, and are associated with a relevant increase in electrolyte leakage (M. Bellando, S. Sacco, F. Albergoni, P. Rocco, M.T. Marre [1997] Bot Acta 110: 388-394). In this paper we report data indicating further analogies between the oxidative burst induced by sulfhydryl blockers in E. densa and that induced by pathogen-derived elicitors in animal and plant cells: (a) NEM- and Ag+-induced DeltaQO2 was associated with H2O2 production and both effects depended on the presence of external Ca2+; (b) Ca2+ influx was markedly increased by treatment with NEM; (c) the Ca2+ channel blocker LaCl3 inhibited DeltaQO2, electrolyte release, and membrane depolarization induced by the sulfhydryl reagents; and (d) LaCl3 also inhibited electrolyte leakage induced by the direct infiltration of the leaves with H2O2. These results suggest a model in which the interaction of sulfhydryl blockers with sulfhydryl groups of cell components would primarily induce an increase in the Ca2+ cytosolic concentration, followed by membrane depolarization and activation of a plasma membrane NADPH oxidase. This latter effect, producing active oxygen species, might further influence plasma membrane permeability, leading to the massive release of electrolytes from the tissue.

  15. The terminal oxidases of Paracoccus denitrificans.

    PubMed

    de Gier, J W; Lübben, M; Reijnders, W N; Tipker, C A; Slotboom, D J; van Spanning, R J; Stouthamer, A H; van der Oost, J

    1994-07-01

    Three distinct types of terminal oxidases participate in the aerobic respiratory pathways of Paracoccus denitrificans. Two alternative genes encoding subunit I of the aa3-type cytochrome c oxidase have been isolated before, namely ctaDI and ctaDII. Each of these genes can be expressed separately to complement a double mutant (delta ctaDI, delta ctaDII), indicating that they are isoforms of subunit I of the aa3-type oxidase. The genomic locus of a quinol oxidase has been isolated: cyoABC. This protohaem-containing oxidase, called cytochrome bb3, is the only quinol oxidase expressed under the conditions used. In a triple oxidase mutant (delta ctaDI, delta ctaDII, cyoB::KmR) an alternative cytochrome c oxidase has been characterized; this cbb3-type oxidase has been partially purified. Both cytochrome aa3 and cytochrome bb3 are redox-driven proton pumps. The proton-pumping capacity of cytochrome cbb3 has been analysed; arguments for and against the active transport of protons by this novel oxidase complex are discussed.

  16. Prokaryotic orthologues of mitochondrial alternative oxidase and plastid terminal oxidase.

    PubMed

    McDonald, Allison E; Amirsadeghi, Sasan; Vanlerberghe, Greg C

    2003-12-01

    The mitochondrial alternative oxidase (AOX) and the plastid terminal oxidase (PTOX) are two similar members of the membrane-bound diiron carboxylate group of proteins. AOX is a ubiquinol oxidase present in all higher plants, as well as some algae, fungi, and protists. It may serve to dampen reactive oxygen species generation by the respiratory electron transport chain. PTOX is a plastoquinol oxidase in plants and some algae. It is required in carotenoid biosynthesis and may represent the elusive oxidase in chlororespiration. Recently, prokaryotic orthologues of both AOX and PTOX proteins have appeared in sequence databases. These include PTOX orthologues present in four different cyanobacteria as well as an AOX orthologue in an alpha-proteobacterium. We used PCR, RT-PCR and northern analyses to confirm the presence and expression of the PTOX gene in Anabaena variabilis PCC 7120. An extensive phylogeny of newly found prokaryotic and eukaryotic AOX and PTOX proteins supports the idea that AOX and PTOX represent two distinct groups of proteins that diverged prior to the endosymbiotic events that gave rise to the eukaryotic organelles. Using multiple sequence alignment, we identified residues conserved in all AOX and PTOX proteins. We also provide a scheme to readily distinguish PTOX from AOX proteins based upon differences in amino acid sequence in motifs around the conserved iron-binding residues. Given the presence of PTOX in cyanobacteria, we suggest that this acronym now stand for plastoquinol terminal oxidase. Our results have implications for the photosynthetic and respiratory metabolism of these prokaryotes, as well as for the origin and evolution of eukaryotic AOX and PTOX proteins.

  17. Alternative splicing and differential expression of two transcripts of nicotine adenine dinucleotide phosphate oxidase B gene from Zea mays.

    PubMed

    Lin, Fan; Zhang, Yun; Jiang, Ming-Yi

    2009-03-01

    With the exception of rice, little is known about the existence of respiratory burst oxidase homolog (rboh) gene in cereals. The present study reports the cloning and analysis of a novel rboh gene, termed ZmrbohB, from maize (Zea mays L.). The full-length cDNA of ZmrbohB encodes a 942 amino acid protein containing all of the respiratory burst oxidase homolog catalytically critical motifs. Alternative splicing of ZmrbohB has generated two transcript isoforms, ZmrbohB-alpha and -beta. Spliced transcript ZmrbohB-beta retains an unspliced intron 11 that carries a premature termination codon and probably leads to nonsense-mediated mRNA decay. Expression analysis showed that two splice isoforms were differentially expressed in various tissues and at different developmental stages, and the major product was ZmrbohB-alpha. The transcripts of ZmrbohB-alpha accumulated markedly when the maize seedlings were subjected to various abiotic stimuli, such as wounding, cold (4 degrees C), heat (40 degrees C), UV and salinity stress. In addition, several abiotic stimuli also affected the alternative splicing pattern of ZmrbohB except wounding. These results provide new insight into roles in the expression regulation of plant rboh genes and suggest that ZmrbohB gene may play a role in response to environmental stresses.

  18. Transcriptional coupling of synaptic transmission and energy metabolism: role of nuclear respiratory factor 1 in co-regulating neuronal nitric oxide synthase and cytochrome c oxidase genes in neurons.

    PubMed

    Dhar, Shilpa S; Liang, Huan Ling; Wong-Riley, Margaret T T

    2009-10-01

    Neuronal activity is highly dependent on energy metabolism; yet, the two processes have traditionally been regarded as independently regulated at the transcriptional level. Recently, we found that the same transcription factor, nuclear respiratory factor 1 (NRF-1) co-regulates an important energy-generating enzyme, cytochrome c oxidase, as well as critical subunits of glutamatergic receptors. The present study tests our hypothesis that the co-regulation extends to the next level of glutamatergic synapses, namely, neuronal nitric oxide synthase, which generates nitric oxide as a downstream signaling molecule. Using in silico analysis, electrophoretic mobility shift assay, chromatin immunoprecipitation, promoter mutations, and NRF-1 silencing, we documented that NRF-1 functionally bound to Nos1, but not Nos2 (inducible) and Nos3 (endothelial) gene promoters. Both COX and Nos1 transcripts were up-regulated by depolarizing KCl treatment and down-regulated by TTX-mediated impulse blockade in neurons. However, NRF-1 silencing blocked the up-regulation of both Nos1 and COX induced by KCl depolarization, and over-expression of NRF-1 rescued both Nos1 and COX transcripts down-regulated by TTX. These findings are consistent with our hypothesis that synaptic neuronal transmission and energy metabolism are tightly coupled at the molecular level.

  19. Identification of a thermolabile component of the human neutrophil NADPH oxidase. A model for chronic granulomatous disease caused by deficiency of the p67-phox cytosolic component.

    PubMed Central

    Erickson, R W; Malawista, S E; Garrett, M C; Van Blaricom, G; Leto, T L; Curnutte, J T

    1992-01-01

    Mild heating of human neutrophils inactivates the respiratory burst oxidase, producing a defect in superoxide production and bacterial killing comparable to that seen in patients afflicted with chronic granulomatous disease (CGD). We have now investigated the mechanism and specificity of this inactivation by examining the effect of mild heating on the known oxidase components: the membrane-bound subunits of the cytochrome b558 (gp91-phox and p22-phox) and the two cytosolic oxidase factors (p47-phox and p67-phox). Heating (46 degrees C for 7.5 min) caused intact neutrophils to lose greater than 85% of their capacity to produce superoxide, a defect which was localized to the cytosolic, but not the membrane, fraction. Complementation studies with CGD cytosols deficient in either p47-phox or p67-phox suggested that the defective component of heat-inactivated cytosol was p67-phox. This was confirmed by experiments showing that recombinant p67-phox, but not p47-phox, exhibited lability at 46 degrees C and completely reconstituted oxidase activity of heat-treated cytosol. These studies indicate that mild heating of either intact neutrophils or normal neutrophil cytosol results in a selective inactivation of p67-phox, providing a model oxidase system for the extremely rare p67-phox-deficient form of CGD. PMID:1314852

  20. When it is too hot for photosynthesis: heat-induced instability of photosynthesis in relation to respiratory burst, cell permeability changes and H₂O₂ formation.

    PubMed

    Hüve, Katja; Bichele, Irina; Rasulov, Bahtijor; Niinemets, Ulo

    2011-01-01

    Photosynthesis rate (A(n)) becomes unstable above a threshold temperature, and the recovery upon return to low temperature varies because of reasons not fully understood. We investigated responses of A(n), dark respiration and chlorophyll fluorescence to supraoptimal temperatures of varying duration and kinetics in Phaseolus vulgaris asking whether the instability of photosynthesis under severe heat stress is associated with cellular damage. Cellular damage was assessed by Evans blue penetration (enhanced membrane permeability) and by H₂O₂ generation [3,3'-diaminobenzidine 4HCl (DAB)-staining]. Critical temperature for dark fluorescence (F(0) ) rise (T(F)) was at 46-48 °C, and a burst of respiration was observed near T(F). However, A(n) was strongly inhibited already before T(F) was reached. Membrane permeability increased with temperature according to a switch-type response, with enhanced permeability observed above 48 °C. Experiments with varying heat pulse lengths and intensities underscored the threshold-type loss of photosynthetic function, and indicated that the degree of photosynthetic deterioration and cellular damage depended on accumulated heat-dose. Beyond the 'point of no return', propagation of cellular damage and reduction of photosynthesis continued upon transfer to lower temperatures and photosynthetic recovery was slow or absent. We conclude that instability of photosynthesis under severe heat stress is associated with time-dependent propagation of cellular lesions.

  1. The activation of the neutrophil respiratory burst by anti-neutrophil cytoplasm autoantibody (ANCA) from patients with systemic vasculitis requires tyrosine kinases and protein kinase C activation

    PubMed Central

    Radford, D J; Lord, J M; Savage, C O S

    1999-01-01

    The ability of antineutrophil cytoplasm autoantibodies (ANCA) from patients with systemic vasculitis to stimulate protein kinase C (PKC) and tyrosine kinases was examined in human neutrophils. Using the superoxide dismutase-inhibitable reduction of ferricytochrome C, the kinetics of ANCA-induced superoxide (O2−) production were characterized and subsequently manipulated by specific inhibitors of PKC and tyrosine kinases. With this approach, ANCA IgG, but not normal IgG or ANCA F(ab′)2 fragments caused a time and dose dependent release of O2− from TNF-α primed neutrophils. The kinetics of ANCA-induced O2− production showed an initial 10–15 min lag phase compared to the N-formyl-l-methionyl-l-leucyl-l-phenylalanine response, suggesting differences in the signalling pathways recruited by these two stimuli. Inhibitor studies revealed that ANCA-activation involved members of both the Ca2+-dependent and -independent PKC isoforms and also tyrosine kinases. ANCA IgG resulted in the translocation of the βII isoform of PKC at a time corresponding to the end of the lag phase of O2− production, suggesting that PKC activity may be instrumental in processes regulating the activity of the NADPH oxidase in response to ANCA. Tyrosine phosphorylation of numerous proteins also peaked 10–15 min after stimulation with ANCA but not normal IgG. These data suggest that PKC and tyrosine kinases regulate O2− production from neutrophils stimulated with autoantibodies from patients with systemic vasculitis. PMID:10540175

  2. Stimulation of cellular XTT reduction by cytochrome oxidase inhibitors.

    PubMed

    Kunimoto, S; Nosaka, C; Takeuchi, T

    1999-06-01

    XTT reducing activity by CHO and L1210 cells was found to be stimulated by the presence of cytochrome oxidase inhibitors such as NaN3 or KCN. Among the other respiratory chain inhibitors, antimycin A (a complex III inhibitor) and chlorpromazine inhibited cellular XTT reduction, and rotenone and malonate showed slight inhibition and no effect, respectively. It is suggested that XTT reduction is coupled with the respiratory chain via cytochrome c, which is located between complexes III and IV (cytochrome oxidase).

  3. [Alternative oxidase - never ending story].

    PubMed

    Szal, Bożena; Rychter, Anna M

    2016-01-01

    Investigations of plant cyanide resistant respiration lead to the discovery in mitochondrial respiratory chain of the second terminal oxidase, alternative oxidase (AOX). AOX transfers electrons from reduced ubiquinone to oxygen omitting two coupling places thus lowering energetic efficiency of respiration. The presence of AOX was shown in all plants and also in some fungi, mollusca and protista. In termogenic plants the activity of AOX is connected with heat production. In other organisms AOX activity is important for maintaining metabolic homeostasis (carbon metabolism, cell redox state and energy demand) and ROS homeostasis. In this article structure of plant AOX protein and the regulation on molecular levels was described. Possible role of AOX as stress marker was pointed and the possibility of using AOX in human gene therapy was discussed.

  4. Influenza infection suppresses NADPH oxidase-dependent phagocytic bacterial clearance and enhances susceptibility to secondary methicillin-resistant Staphylococcus aureus infection.

    PubMed

    Sun, Keer; Metzger, Dennis W

    2014-04-01

    Methicillin-resistant Staphylococcus aureus (MRSA) has emerged as a leading contributor to mortality during recent influenza pandemics. The mechanism for this influenza-induced susceptibility to secondary S. aureus infection is poorly understood. In this study, we show that innate antibacterial immunity was significantly suppressed during the recovery stage of influenza infection, even though MRSA superinfection had no significant effect on viral burdens. Compared with mice infected with bacteria alone, postinfluenza MRSA-infected mice exhibited impaired bacterial clearance, which was not due to defective phagocyte recruitment, but rather coincided with reduced intracellular reactive oxygen species levels in alveolar macrophages and neutrophils. NADPH oxidase is responsible for reactive oxygen species production during phagocytic bacterial killing, a process also known as oxidative burst. We found that gp91(phox)-containing NADPH oxidase activity in macrophages and neutrophils was essential for optimal bacterial clearance during respiratory MRSA infections. In contrast to wild-type animals, gp91(phox-/-) mice exhibited similar defects in MRSA clearance before and after influenza infection. Using gp91(phox+/-) mosaic mice, we further demonstrate that influenza infection inhibits a cell-intrinsic contribution of NADPH oxidase to phagocyte bactericidal activity. Taken together, our results establish that influenza infection suppresses NADPH oxidase-dependent bacterial clearance and leads to susceptibility to secondary MRSA infection.

  5. Hydrogen peroxide produced by NADPH oxidases increases proline accumulation during salt or mannitol stress in Arabidopsis thaliana.

    PubMed

    Ben Rejeb, Kilani; Lefebvre-De Vos, Delphine; Le Disquet, Isabel; Leprince, Anne-Sophie; Bordenave, Marianne; Maldiney, Régis; Jdey, Asma; Abdelly, Chedly; Savouré, Arnould

    2015-12-01

    Many plants accumulate proline, a compatible osmolyte, in response to various environmental stresses such as water deficit and salinity. In some stress responses, plants generate hydrogen peroxide (H2 O2 ) that mediates numerous physiological and biochemical processes. The aim was to study the relationship between stress-induced proline accumulation and H2 O2 production. Using pharmacological and reverse genetic approaches in Arabidopsis thaliana, we investigated the role of NADPH oxidases, Respiratory burst oxidase homologues (Rboh), in the induction of proline accumulation was investigated in response to stress induced by either 200 mM NaCl or 400 mM mannitol. Stress from NaCl or mannitol resulted in a transient increase in H2 O2 content accompanied by accumulation of proline. Dimethylthiourea, a scavenger of H2 O2 , and diphenylene iodonium (DPI), an inhibitor of H2 O2 production by NADPH oxidase, were found to significantly inhibit proline accumulation in these stress conditions. DPI also reduced the expression level of Δ(1) -pyrroline-5-carboxylate synthetase, the key enzyme involved in the biosynthesis of proline. Similarly, less proline accumulated in knockout mutants lacking either AtRbohD or AtRbohF than in wild-type plants in response to the same stresses. Our data demonstrate that AtRbohs (A. thaliana Rbohs) contribute to H2 O2 production in response to NaCl or mannitol stress to increase proline accumulation in this plant.

  6. Lipopolysaccharides elicit an oxidative burst as a component of the innate immune system in the seagrass Thalassia testudinum.

    PubMed

    Loucks, Kyle; Waddell, David; Ross, Cliff

    2013-09-01

    This study represents the first report characterizing the biological effects of a lipopolysaccharide (LPS) immune modulator on a marine vascular plant. LPS was shown to serve as a strong elicitor of the early defense response in the subtropical seagrass Thalassia testudinum Banks ex König and was capable of inducing an oxidative burst identified at the single cell level. The formation of reactive oxygen species (ROS), detected by a redox-sensitive fluorescent probe and luminol-based chemiluminescence, included a diphenyleneiodonium sensitive response, suggesting the involvement of an NADPH oxidase. A 900 bp cDNA fragment coding for this enzyme was sequenced and found to encode a NAD binding pocket domain with extensive homology to the Arabidopsis thaliana rbohF (respiratory burst oxidase homolog) gene. The triggered release of ROS occurred at 20 min post-elicitation and was dose-dependent, requiring a minimal threshold of 50 μg/mL LPS. Pharmacological dissection of the early events preceding ROS emission indicated that the signal transduction chain of events involved extracellular alkalinization, G-proteins, phospholipase A2, as well as K(+), Ca(2+), and anion channels. Despite exclusively thriving in a marine environment, seagrasses contain ROS-generating machinery and signal transduction components that appear to be evolutionarily conserved with the well-characterized defense response systems found in terrestrial plants.

  7. NADPH Oxidase-Dependent Superoxide Production in Plant Reproductive Tissues.

    PubMed

    Jiménez-Quesada, María J; Traverso, José Á; Alché, Juan de Dios

    2016-01-01

    In the life cycle of a flowering plant, the male gametophyte (pollen grain) produced in the anther reaches the stigmatic surface and initiates the pollen-pistil interaction, an important step in plant reproduction, which ultimately leads to the delivery of two sperm cells to the female gametophyte (embryo sac) inside the ovule. The pollen tube undergoes a strictly apical expansion characterized by a high growth rate, whose targeting should be tightly regulated. A continuous exchange of signals therefore takes place between the haploid pollen and diploid tissue of the pistil until fertilization. In compatible interactions, theses processes result in double fertilization to form a zygote (2n) and the triploid endosperm. Among the large number of signaling mechanisms involved, the redox network appears to be particularly important. Respiratory burst oxidase homologs (Rbohs) are superoxide-producing enzymes involved in a broad range of processes in plant physiology. In this study, we review the latest findings on understanding Rboh activity in sexual plant reproduction, with a particular focus on the male gametophyte from the anther development stages to the crowning point of fertilization. Rboh isoforms have been identified in both the male and female gametophyte and have proven to be tightly regulated. Their role at crucial points such as proper growth of pollen tube, self-incompatibility response and eventual fertilization is discussed.

  8. A Medicago truncatula NADPH oxidase is involved in symbiotic nodule functioning

    PubMed Central

    Marino, Daniel; Andrio, Emilie; Danchin, Etienne G J; Oger, Elodie; Gucciardo, Sébastien; Lambert, Annie; Puppo, Alain; Pauly, Nicolas

    2011-01-01

    Summary The plant plasma membrane-localized NADPH oxidases, known as respiratory burst oxidase homologues (RBOHs), appear to play crucial roles in plant growth and development. They are involved in important processes, such as root hair growth, plant defence reactions and abscisic acid signalling.Using sequence similarity searches, we identified seven putative RBOH-encoding genes in the Medicago truncatula genome. A phylogenetic reconstruction showed that Rboh gene duplications occurred in legume species. We analysed the expression of these MtRboh genes in different M. truncatula tissues: one of them, MtRbohA, was significantly up-regulated in Sinorhizobium meliloti-induced symbiotic nodules.MtRbohA expression appeared to be restricted to the nitrogen-fixing zone of the functional nodule. Moreover, using S. meliloti bacA and nifH mutants unable to form efficient nodules, a strong link between nodule nitrogen fixation and MtRbohA up-regulation was shown. MtRbohA expression was largely enhanced under hypoxic conditions. Specific RNA interference for MtRbohA provoked a decrease in the nodule nitrogen fixation activity and the modulation of genes encoding the microsymbiont nitrogenase.These results suggest that hypoxia, prevailing in the nodule-fixing zone, may drive the stimulation of MtRbohA expression, which would, in turn, lead to the regulation of nodule functioning. PMID:21155825

  9. Effect of naphthalene on cytochrome oxidase activity

    SciTech Connect

    Harmon, H.J.

    1988-01-01

    Previous reports have demonstrated that naphthalene inhibits oxygen consumption in Daphnia magna tissue culture cells, and intact mitochondria and submitochondrial particles. These studies were extended to algal mitochondrial respiration as well as photosynthetic activity. The authors were able to demonstrate the specific site of apparent respiratory inhibition to be coenzyme Q (ubiquinone, UQ) and later to demonstrate the molecular basis of this inhibition at ubiquinone. The authors previously could not demonstrate an effect of naphthalene on cytochrome oxidase activity. However, the observation that naphthalene can stimulate respiration in algae prompted the reinvestigation of the effect of naphthalene on the kinetics of cytochrome oxidase. Cytochrome oxidase is a multi-subunit membranous protein responsible for the oxidation of cytochrome c and the reduction of molecular oxygen to water. Because of the complicated nature and mechanism of this enzyme, the potential exists for multiple and possibly opposite effects of naphthalene on its function.

  10. Nicotinamide Effects Oxidative Burst Activity of Neutrophils in Patients with Poorly Controlled Type 2 Diabetes Mellitus

    PubMed Central

    Samanci, Tülay; Demirel, Gülderen Yanikkaya; Damci, Taner; Ilkova, Hasan

    2004-01-01

    Neutrophil functions are impaired in patients with diabetes mellitus. Bacterial phagocytosis and oxidative burst activity are reduced at high glucose concentrations in diabetic patients. Defects in neutrophil oxidative burst capacity are of multifactorial origin in diabetes mellitus and correlate with glucose levels. It has been reported that neutrophil NADPH oxidase activity is impaired and superoxide production is reduced in diabetic patients with or without any infections. Nicotinamide is a vitamin B3 derivative and a NAD precursor with immunomodulatory effects. In vitro studies demonstrated that nicotinamide increases NAD and NADH content of beta cells. The authors hypothesized that nicotinamide may restore the impaired oxidative burst capacity of neutrophils in diabetic patients by increasing the NADH content as an electron donor and possibly through NADPH oxidase activity of the cell. In order to test the hypothesis, this placebo-controlled and open study was designed to evaluate neutrophil functions in infection-free poorly controlled type 2 diabetic patients as compared to healthy subjects and assess the effects of nicotinamide on neutrophil phagocytosis as well as oxidative burst activity. Thirty patients with type 2 diabetes mellitus were enrolled in the study. Sixteen were females and 14 were males, with a mean age 58 ± 10. All patients were on sulphonylurea treatment and their hemoglobin A1c (HbA1c) levels were above 7.5%. The control group consisted of 10 voluntary healthy subjects. Diabetic and control subjects were not significantly different in terms of age, body mass index (BMI), leucocyte and neutrophil counts, C-reactive protein (CRP) level, and erythrocyte sedimentation rate (ESR), but HbA1c and fasting glucose levels were significantly higher in patients with diabetes mellitus. Phagocytic activity and respiratory burst indexes were measured by flow cytometric analyses as previously described by Rothe and Valet (Methods Enzyml., 233, 539–548

  11. Tomato SlRbohB, a member of the NADPH oxidase family, is required for disease resistance against Botrytis cinerea and tolerance to drought stress

    PubMed Central

    Li, Xiaohui; Zhang, Huijuan; Tian, Limei; Huang, Lei; Liu, Shixia; Li, Dayong; Song, Fengming

    2015-01-01

    NADPH oxidases (also known as respiratory burst oxidase homologs, Rbohs) are key enzymes that catalyze the generation of reactive oxygen species (ROS) in plants. In the present study, eight SlRboh genes were identified in tomato and their possible involvement in resistance to Botrytis cinerea and drought tolerance was examined. Expression of SlRbohs was induced by B. cinerea and Pseudomonas syringae pv. tomato but displayed distinct patterns. Virus-induced gene silencing based silencing of SlRbohB resulted in reduced resistance to B. cinerea but silencing of other SlRbohs did not affect the resistance. Compared to non-silenced plants, the SlRbohB-silenced plants accumulated more ROS and displayed attenuated expression of defense genes after infection with B. cinerea. Silencing of SlRbohB also suppressed flg22-induced ROS burst and the expression of SlLrr22, a marker gene related to PAMP-triggered immunity (PTI). Transient expression of SlRbohB in Nicotiana benthamiana led to enhanced resistance to B. cinerea. Furthermore, silencing of SlRbohB resulted in decreased drought tolerance, accelerated water loss in leaves and the altered expression of drought-responsive genes. Our data demonstrate that SlRbohB positively regulates the resistance to B. cinerea, flg22-induced PTI, and drought tolerance in tomato. PMID:26157450

  12. The NADH oxidase-Prx system in Amphibacillus xylanus.

    PubMed

    Niimura, Youichi

    2007-01-01

    Amphibacillus NADH oxidase belongs to a growing new family of peroxiredoxin-linked oxidoreductases including alkyl hydroperoxide reductase F (AhpF). Like AhpF it displays extremely high hydroperoxide reductase activity in the presence of a Prx, thus making up the NADH oxidase-Prx system. The NADH oxidase primarily catalyzes the reduction of oxygen by NADH to form H2O2, while the Prx immediately reduces H2O2 (or ROOH) to water (or ROH). Consequently, the NADH oxidase-Prx system catalyzes the reduction of both oxygen and hydrogen peroxide to water with NADH as the preferred electron donor. The NADH oxidase-Prx system is widely distributed in aerobically growing bacteria lacking a respiratory chain and catalase, and plays an important role not only in scavenging hydroperoxides but also in regenerating NAD in these bacteria.

  13. Analysis of PAMP-Triggered ROS Burst in Plant Immunity.

    PubMed

    Sang, Yuying; Macho, Alberto P

    2017-01-01

    The plant perception of pathogen-associated molecular patterns triggers a plethora of cellular immune responses. One of these responses is a rapid and transient burst of reactive oxygen species (ROS) mediated by plasma membrane-localized NADPH oxidases. The ROS burst requires a functional receptor complex and the contribution of several additional regulatory components. In laboratory conditions, the ROS burst can be detected a few minutes after the treatment with an immunogenic microbial elicitor. For these reasons, the elicitor-triggered ROS burst has been often exploited as readout to probe the contribution of plant components to early immune responses. Here, we describe a detailed protocol for the measurement of elicitor-triggered ROS burst in a simple, fast, and easy manner.

  14. Respiratory System

    MedlinePlus

    ... this page from the NHLBI on Twitter. The Respiratory System The respiratory system is made up of organs ... vessels, and the muscles that enable breathing. The Respiratory System Figure A shows the location of the respiratory ...

  15. Mitochondrial cytochrome c oxidase deficiency.

    PubMed

    Rak, Malgorzata; Bénit, Paule; Chrétien, Dominique; Bouchereau, Juliette; Schiff, Manuel; El-Khoury, Riyad; Tzagoloff, Alexander; Rustin, Pierre

    2016-03-01

    As with other mitochondrial respiratory chain components, marked clinical and genetic heterogeneity is observed in patients with a cytochrome c oxidase deficiency. This constitutes a considerable diagnostic challenge and raises a number of puzzling questions. So far, pathological mutations have been reported in more than 30 genes, in both mitochondrial and nuclear DNA, affecting either structural subunits of the enzyme or proteins involved in its biogenesis. In this review, we discuss the possible causes of the discrepancy between the spectacular advances made in the identification of the molecular bases of cytochrome oxidase deficiency and the lack of any efficient treatment in diseases resulting from such deficiencies. This brings back many unsolved questions related to the frequent delay of clinical manifestation, variable course and severity, and tissue-involvement often associated with these diseases. In this context, we stress the importance of studying different models of these diseases, but also discuss the limitations encountered in most available disease models. In the future, with the possible exception of replacement therapy using genes, cells or organs, a better understanding of underlying mechanism(s) of these mitochondrial diseases is presumably required to develop efficient therapy.

  16. Mitochondrial Cytochrome c Oxidase Deficiency

    PubMed Central

    Rak, Malgorzata; Bénit, Paule; Chrétien, Dominique; Bouchereau, Juliette; Schiff, Manuel; El-Khoury, Riyad; Tzagoloff, Alexander; Rustin, Pierre

    2016-01-01

    As with other mitochondrial respiratory chain components, marked clinical and genetic heterogeneity is observed in patients with a cytochrome c oxidase deficiency. This constitutes a considerable diagnostic challenge and raises a number of puzzling questions. So far, pathological mutations have been reported in more than 30 genes, in both mitochondrial and nuclear DNA, affecting either structural subunits of the enzyme or proteins involved in its biogenesis. In this review, we discuss the possible causes of the discrepancy between the spectacular advances made in the identification of the molecular bases of cytochrome oxidase deficiency and the lack of any efficient treatment in diseases resulting from such deficiencies. This brings back many unsolved questions related to the frequent delay of clinical manifestation, variable course and severity, and tissue-involvement often associated with these diseases. In this context, we stress the importance to study different models of these diseases, but also discuss the limitations encountered in most available disease models. In the future, with the possible exception of replacement therapy using genes, cells or organs, a better understanding of underlying mechanism(s) of these mitochondrial diseases is presumably required to develop efficient therapy. PMID:26846578

  17. Isolation and purification of the cytochrome oxidase of Azotobacter vinelandii.

    PubMed

    Jurtshuk, P; Mueller, T J; Wong, T Y

    1981-09-14

    A membrane-bound cytochrome oxidase for Azobacter vinelandii was purified 20-fold using a detergent-solubilization procedure. Activity was monitored using as ascorbate-TMPD oxidation assay. The oxidase was 'solubilized' from a sonic-type electron-transport particle (R3 fraction) using Triton X-100 and deoxycholate. Low detergent concentrations first solubilized the flavoprotein oxidoreductases, then higher concentrations of Triton X-100 and KCl solubilized the oxidase, which was precipitated at 27-70% (NH4)2SO4. The highly purified cytochrome oxidase has a V of 60-78 microgatom O consumed/min per mg protein. TMPD oxidation by the purified enzyme was inhibited by CO, KCN, NaN3 and NH2OH; NaNO2 (but not NaNO3) also had a potent inhibitory effect. Spectral analyses revealed two major hemoproteins, the c-type cytochrome c4 and cytochrome o; cytochromes a1 and d were not detected. The Azotobacter cytochrome oxidase is an integrated cytochrome c4-o complex, TMPD-dependent cytochrome oxidase activity being highest in preparations having a high c-type cytochrome content. This TMPD-dependent cytochrome oxidase serves as a major oxygen-activation site for the A. vinelandii respiratory chain. It appears functionally analogous to cytochrome a+a3 oxidase of mammalian mitochondria.

  18. How Long does a Burst Burst?

    NASA Astrophysics Data System (ADS)

    Zhang, Bin-Bin; Zhang, Bing; Murase, Kohta; Connaughton, Valerie; Briggs, Michael S.

    2014-05-01

    Several gamma-ray bursts (GRBs) last much longer (~hours) in γ-rays than typical long GRBs (~minutes), and it has recently been proposed that these "ultra-long GRBs" may form a distinct population, probably with a different (e.g., blue supergiant) progenitor than typical GRBs. However, Swift observations suggest that many GRBs have extended central engine activities manifested as flares and internal plateaus in X-rays. We perform a comprehensive study on a large sample of Swift GRBs with X-Ray Telescope observations to investigate GRB central engine activity duration and to determine whether ultra-long GRBs are unusual events. We define burst duration t burst based on both γ-ray and X-ray light curves rather than using γ-ray observations alone. We find that t burst can be reliably measured in 343 GRBs. Within this "good" sample, 21.9% GRBs have t burst >~ 103 s and 11.5% GRBs have t burst >~ 104 s. There is an apparent bimodal distribution of t burst in this sample. However, when we consider an "undetermined" sample (304 GRBs) with t burst possibly falling in the gap between GRB duration T 90 and the first X-ray observational time, as well as a selection effect against t burst falling into the first Swift orbital "dead zone" due to observation constraints, the intrinsic underlying t burst distribution is consistent with being a single component distribution. We found that the existing evidence for a separate ultra-long GRB population is inconclusive, and further multi-wavelength observations are needed to draw a firmer conclusion. We also discuss the theoretical implications of our results. In particular, the central engine activity duration of GRBs is generally much longer than the γ-ray T 90 duration and it does not even correlate with T 90. It would be premature to make a direct connection between T 90 and the size of the progenitor star.

  19. Burst-by-burst laser frequency monitor

    NASA Technical Reports Server (NTRS)

    Esproles, Carlos (Inventor)

    1994-01-01

    The invention is a system for real-time frequency monitoring and display of an RF burst where the burst frequency is analyzed and displayed on a burst-by-burst basis in order to allow for frequency control. Although the invention was made for monitoring the laser frequency of a LIDAR system, it has other applications where realtime monitoring is required. The novelty of the invention resides in the use of a counter that is reset at the beginning of each unit time of monitoring and then gated for a unit of time. The invention also has an LED bar graph for displaying the measure of frequency at the end of each unit time in either a bar length mode or a moving dot mode. In the latter mode, the operator makes necessary adjustments to maintain the dot at the center of the bar graph.

  20. A biochemical approach to study the role of the terminal oxidases in aerobic respiration in Shewanella oneidensis MR-1.

    PubMed

    Le Laz, Sébastien; Kpebe, Arlette; Bauzan, Marielle; Lignon, Sabrina; Rousset, Marc; Brugna, Myriam

    2014-01-01

    The genome of the facultative anaerobic γ-proteobacterium Shewanella oneidensis MR-1 encodes for three terminal oxidases: a bd-type quinol oxidase and two heme-copper oxidases, a A-type cytochrome c oxidase and a cbb 3-type oxidase. In this study, we used a biochemical approach and directly measured oxidase activities coupled to mass-spectrometry analysis to investigate the physiological role of the three terminal oxidases under aerobic and microaerobic conditions. Our data revealed that the cbb 3-type oxidase is the major terminal oxidase under aerobic conditions while both cbb 3-type and bd-type oxidases are involved in respiration at low-O2 tensions. On the contrary, the low O2-affinity A-type cytochrome c oxidase was not detected in our experimental conditions even under aerobic conditions and would therefore not be required for aerobic respiration in S. oneidensis MR-1. In addition, the deduced amino acid sequence suggests that the A-type cytochrome c oxidase is a ccaa 3-type oxidase since an uncommon extra-C terminal domain contains two c-type heme binding motifs. The particularity of the aerobic respiratory pathway and the physiological implication of the presence of a ccaa 3-type oxidase in S. oneidensis MR-1 are discussed.

  1. Changes in Activities of Respiratory Enzymes in Lungs of Guinea-pigs Exposed to Silica Dust: II. Comparison of the Effects of Quartz Dust and Lampblack on the Succinate Oxidase System

    PubMed Central

    Breyer, Maria G.; Kilroe-Smith, T. A.; Prinsloo, H.

    1964-01-01

    Kilroe-Smith and Breyer (1963) reported that in the early stages of silicosis in guinea-pigs exposed to the inhalation of quartz dust, before the formation of collagen, there were increases in the specific activities of the complete succinate oxidase system and succinate dehydrogenase. The effects on these enzymes of quartz dust have now been compared with the effects of the fibrogenically `inert' lampblack. Lampblack causes a slight increase in the specific activities of these enzymes but the effects are small compared to those caused by quartz. Lampblack also causes a much smaller increase in lung weight than quartz, thus the enzyme increases are roughly parallel to the rise in lung weight. It appears that the effects observed on the enzymes are part of the general pattern associated with the early stages of the development of silicosis. PMID:14106132

  2. Cox26 is a novel stoichiometric subunit of the yeast cytochrome c oxidase.

    PubMed

    Levchenko, Maria; Wuttke, Jan-Moritz; Römpler, Katharina; Schmidt, Bernhard; Neifer, Klaus; Juris, Lisa; Wissel, Mirjam; Rehling, Peter; Deckers, Markus

    2016-07-01

    The cytochrome c oxidase (COX) is the terminal enzyme of the respiratory chain. The complex accepts electrons from cytochrome c and passes them onto molecular oxygen. This process contributes to energy capture in the form of a membrane potential across the inner membrane. The enzyme complex assembles in a stepwise process from the three mitochondria-encoded core subunits Cox1, Cox2 and Cox3, which associate with nuclear-encoded subunits and cofactors. In the yeast Saccharomyces cerevisiae, the cytochrome c oxidase associates with the bc1-complex into supercomplexes, allowing efficient energy transduction. Here we report on Cox26 as a protein found in respiratory chain supercomplexes containing cytochrome c oxidase. Our analyses reveal Cox26 as a novel stoichiometric structural subunit of the cytochrome c oxidase. A loss of Cox26 affects cytochrome c oxidase activity and respirasome organization.

  3. The Terminal Oxidase Cytochrome bd Promotes Sulfide-resistant Bacterial Respiration and Growth

    PubMed Central

    Forte, Elena; Borisov, Vitaliy B.; Falabella, Micol; Colaço, Henrique G.; Tinajero-Trejo, Mariana; Poole, Robert K.; Vicente, João B.; Sarti, Paolo; Giuffrè, Alessandro

    2016-01-01

    Hydrogen sulfide (H2S) impairs mitochondrial respiration by potently inhibiting the heme-copper cytochrome c oxidase. Since many prokaryotes, including Escherichia (E.) coli, generate H2S and encounter high H2S levels particularly in the human gut, herein we tested whether bacteria can sustain sulfide-resistant O2-dependent respiration. E. coli has three respiratory oxidases, the cyanide-sensitive heme-copper bo3 enzyme and two bd oxidases much less sensitive to cyanide. Working on the isolated enzymes, we found that, whereas the bo3 oxidase is inhibited by sulfide with half-maximal inhibitory concentration IC50 = 1.1 ± 0.1 μM, under identical experimental conditions both bd oxidases are insensitive to sulfide up to 58 μM. In E. coli respiratory mutants, both O2-consumption and aerobic growth proved to be severely impaired by sulfide when respiration was sustained by the bo3 oxidase alone, but unaffected by ≤200 μM sulfide when either bd enzyme acted as the only terminal oxidase. Accordingly, wild-type E. coli showed sulfide-insensitive respiration and growth under conditions favouring the expression of bd oxidases. In all tested conditions, cyanide mimicked the functional effect of sulfide on bacterial respiration. We conclude that bd oxidases promote sulfide-resistant O2-consumption and growth in E. coli and possibly other bacteria. The impact of this discovery is discussed. PMID:27030302

  4. The Terminal Oxidase Cytochrome bd Promotes Sulfide-resistant Bacterial Respiration and Growth.

    PubMed

    Forte, Elena; Borisov, Vitaliy B; Falabella, Micol; Colaço, Henrique G; Tinajero-Trejo, Mariana; Poole, Robert K; Vicente, João B; Sarti, Paolo; Giuffrè, Alessandro

    2016-03-31

    Hydrogen sulfide (H2S) impairs mitochondrial respiration by potently inhibiting the heme-copper cytochrome c oxidase. Since many prokaryotes, including Escherichia (E.) coli, generate H2S and encounter high H2S levels particularly in the human gut, herein we tested whether bacteria can sustain sulfide-resistant O2-dependent respiration. E. coli has three respiratory oxidases, the cyanide-sensitive heme-copper bo3 enzyme and two bd oxidases much less sensitive to cyanide. Working on the isolated enzymes, we found that, whereas the bo3 oxidase is inhibited by sulfide with half-maximal inhibitory concentration IC50 = 1.1 ± 0.1 μM, under identical experimental conditions both bd oxidases are insensitive to sulfide up to 58 μM. In E. coli respiratory mutants, both O2-consumption and aerobic growth proved to be severely impaired by sulfide when respiration was sustained by the bo3 oxidase alone, but unaffected by ≤200 μM sulfide when either bd enzyme acted as the only terminal oxidase. Accordingly, wild-type E. coli showed sulfide-insensitive respiration and growth under conditions favouring the expression of bd oxidases. In all tested conditions, cyanide mimicked the functional effect of sulfide on bacterial respiration. We conclude that bd oxidases promote sulfide-resistant O2-consumption and growth in E. coli and possibly other bacteria. The impact of this discovery is discussed.

  5. The GLAST Burst Monitor

    NASA Technical Reports Server (NTRS)

    Meegan, Charles; Bhat, Narayana; Connaughton, Valerie; Briggs, Michael; Diehl, Roland; Fishman, Gerald; Greiner, Jochen; Kippen, R. Marc; vonKienlin, Andreas; Kouveliotou, Chryssa; Lichti, Giselher; Paciesas, William; Preece, Robert; Steinle, Helmut; Wilson-Hodge, Colleen

    2007-01-01

    The GLAST Burst Monitor (GBM) comprises an array of NaI and BGO scintillation detectors designed to enhance the scientific return from GLAST in the study of gamma-ray bursts (GRBs). By observing in the 10 keV to 30 MeV energy range, GBM extends the spectral coverage of GRBs more than 3 decades below the LAT energy threshold. GBM computes burst locations on-board, allowing repointing of the GLAST Observatory to place strong bursts within the LAT field-of-view to observe delayed high-energy emission.

  6. Propeller tone bursts

    NASA Technical Reports Server (NTRS)

    Succi, G. P.; Munro, D. H.; Ingard, K. U.

    1983-01-01

    Intense high frequency (25-38 kHz) tone bursts have been observed in acoustic tests of a scale model of a general aviation propeller. The amplitude of the tone burst is approximately equal to the amplitude of the propeller noise signature. The conditions necessary for the production of these tone bursts are described. The experiments indicate that the origin of these bursts is a periodic flow oscillation on the suction surface of the propeller blade tips which may be due to the interaction between an oscillating shock wave and a laminar boundary layer.

  7. Voltage-Gated Proton Channels as Novel Drug Targets: From NADPH Oxidase Regulation to Sperm Biology

    PubMed Central

    Demaurex, Nicolas; Krause, Karl-Heinz

    2015-01-01

    Abstract Significance: Voltage-gated proton channels are increasingly implicated in cellular proton homeostasis. Proton currents were originally identified in snail neurons less than 40 years ago, and subsequently shown to play an important auxiliary role in the functioning of reactive oxygen species (ROS)-generating nicotinamide adenine dinucleotide phosphate (NADPH) oxidases. Molecular identification of voltage-gated proton channels was achieved less than 10 years ago. Interestingly, so far, only one gene coding for voltage-gated proton channels has been identified, namely hydrogen voltage-gated channel 1 (HVCN1), which codes for the HV1 proton channel protein. Over the last years, the first picture of putative physiological functions of HV1 has been emerging. Recent Advances: The best-studied role remains charge and pH compensation during the respiratory burst of the phagocyte NADPH oxidase (NOX). Strong evidence for a role of HV1 is also emerging in sperm biology, but the relationship with the sperm NOX5 remains unclear. Probably in many instances, HV1 functions independently of NOX: for example in snail neurons, basophils, osteoclasts, and cancer cells. Critical Issues: Generally, ion channels are good drug targets; however, this feature has so far not been exploited for HV1, and hitherto no inhibitors compatible with clinical use exist. However, there are emerging indications for HV1 inhibitors, ranging from diseases with a strong activation of the phagocyte NOX (e.g., stroke) to infertility, osteoporosis, and cancer. Future Directions: Clinically useful HV1-active drugs should be developed and might become interesting drugs of the future. Antioxid. Redox Signal. 23, 490–513. PMID:24483328

  8. Respiratory acidosis

    MedlinePlus

    ... Names Ventilatory failure; Respiratory failure; Acidosis - respiratory Images Respiratory system References Effros RM, Swenson ER. Acid-base balance. In: Broaddus VC, Mason RJ, Ernst JD, et al, eds. Murray and Nadel's Textbook of Respiratory Medicine . 6th ed. Philadelphia, PA: Elsevier Saunders; 2016: ...

  9. Neutrino bursts from gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Paczynski, Bohdan; Xu, Guohong

    1994-01-01

    If gamma-ray bursts originate at cosmological distances, as strongly indicated by the results from Burst and Transient Source Experiment (BATSE) on the Compton Gamma-Ray Observatory (CGRO), then ultrarelativistic ejecta are the likely consequence of the highly super-Eddington luminosity of the sources. If the energy injection rate varies with time, then the Lorentz factor of the wind also varies, and the shells of ejected matter collide with each other. The collisions between baryons produce pions which decay into high-energy photons, electrons, electron positron pairs, and neutrino pairs. The bulk Lorentz factor of approximately 300 is required if our model is to be compatible with the observed millisecond variability. The strongest gamma-ray bursts are observed to deliver approximately 10(exp -4) ergs/sq cm in 100-200 keV photons. In our scenario more energy may be delivered in a neutrino burst. Typical neutrinos may be approximately 30 GeV if the protons have a Maxwellian energy distribution, and up to approximately TeV if the protons have a power-law distribution. Such neutrino bursts are close to the detection limit of the DUMAND II experiment.

  10. Respiration of bloodstream forms of the parasite Trypanosoma brucei brucei is dependent on a plant-like alternative oxidase.

    PubMed

    Clarkson, A B; Bienen, E J; Pollakis, G; Grady, R W

    1989-10-25

    CoQ links the sn-glycerol-3-phosphate dehydrogenase and oxidase components of the cyanide-insensitive, non-cytochrome-mediated respiratory system of bloodstream African trypanosomes. In this and other characteristics, their respiratory system is similar to the alternative oxidase of plants. The parasites contain 206 ng of CoQ9 mg protein-1 which co-sediments with respiratory activity. The redox state of this CoQ responds in a manner consistent with respiratory function: 60% being in the reduced form when substrate is available and the oxidase is blocked; 13% being in the reduced form when the oxidase is functioning and there is no substrate. The addition of CoQ to aceton-extracted cells stimulates salicylhydroxamic acid-sensitive respiration by 56%. After inhibition of respiration by digitonin-mediated dispersal of the electron transport components, liposomes restore 40% of respiratory activity while liposomes containing CoQ restore 66% of this activity. A less hydrophobic analogue, reduced decyl CoQ, serves as a direct substrate for the trypanosome oxidase supporting full salicylhydroxamic acid-sensitive respiration. After digitonin disruption of electron transport, the nonreduced form of this synthetic substrate can reestablish the chain by accepting electrons from dispersed sn-glycerol-3-phosphate dehydrogenase and transferring them to the dispersed oxidase. Similarities between the alternative oxidase of plants and the oxidase of the trypanosome respiratory system include: mitochondrial location, lack of oxidative phosphorylation, linkage of a dehydrogenase and an oxidase by CoQ, lack of sensitivity to a range of mitochondrial inhibitors, and sensitivity to a spectrum of inhibitors which selectively block transfer of electrons from reduced CoQ to the terminal oxidase but do not block electron transfer to the cytochrome bc1 complex of the mammalian cytochrome chain.

  11. SHEBA prompt burst dynamics

    SciTech Connect

    Kimpland, R.

    1997-12-31

    The Solution High-Energy Burst Assembly (SHEBA), located at the Los Alamos Critical Experiments Facility, is a homogeneous liquid-fueled reactor that is being prepared for prompt burst operation. As part of the preparations, a reactor safety study was performed in support of the new SHEBA experiment plan. This study looked at the maximum power, total energy yield, and maximum transient pressures that may occur in the reactor during prompt burst operation. The goal of this study is to analyze the neutronic and hydrodynamic behavior of the reactor during burst operation, and to ensure that prompt burst operation does not damage the reactor or exceed the safety envelope of the facility`s Safety Analysis Report (SAR).

  12. Gamma Ray Bursts - Observations

    NASA Technical Reports Server (NTRS)

    Gehrels, N.; Cannizzo, J. K.

    2010-01-01

    We are in an exciting period of discovery for gamma-ray bursts. The Swift observatory is detecting 100 bursts per year, providing arcsecond localizations and sensitive observations of the prompt and afterglow emission. The Fermi observatory is observing 250 bursts per year with its medium-energy GRB instrument and about 10 bursts per year with its high-energy LAT instrument. In addition, rapid-response telescopes on the ground are providing new capabilities to study optical emission during the prompt phase and spectral signatures of the host galaxies. The combined data set is enabling great advances in our understanding of GRBs including afterglow physics, short burst origin, and high energy emission.

  13. Use of a quantitative oxidase test for characterizing oxidative metabolism in bacteria.

    PubMed Central

    Jurtshuk, P; McQuitty, D N

    1976-01-01

    It was possible to quantitate the terminal oxidase(s) reaction using bacterial resting-cell suspensions and demonstrate the usefulness of this reaction for taxonomic purposes. Resting-cell suspensions of physiologically diverse bacteria were examined for their capabilities of oxidizing N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD) using a manometric assay. For organisms having this capability, it was possible to calculate the conventional TMPD oxidase Q(O2) value (microliters of O2 consumed per hour per milligram [dry weight]). All cultures were grown heterotrophically at 30 C, under identical nutritional conditions, and were harvested at the late-logarithmic growth phase. The TMPD oxidase Q(O2) values showed perfect correlation with the Kovacs oxidase test and, in addition, it was possible to define quantitatively that point which separated oxidase-positive from oxidase-negative bacteria. Oxidase-negative bacteria exhibited a TMPD oxidase Q(O2) value (after correcting for the endogenous by substraction) of less than or equal 33 and had an uncorrected TMPD/endogenous ratio of less than or equal 5. The TMPD oxidase Q(O2) values were also correlated with the data obtained for the Hugh-Leifson Oxferm test. In general, bacteria that exhibited a respiratory mechanism had high TMPD oxidase values, whereas fermentative organsims had low TMPD oxidase activity. All exceptions to this are noted. This quantitative study also demonstrated that organisms that (i) lack a type c cytochrome, or (ii) lack a cytochrome-containing electron transport system, like the lactic acid bacteria, exhibited low or negligible TMPD oxidase Q(O2) values. From the 79 bacterial species (36 genera) examined, it appears that this quantitative oxidase test has taxonomic value that can differentiate the oxidative relationships between bacteria at the subspecies, species, and genera levels. PMID:1275489

  14. Arabidopsis alternative oxidase sustains Escherichia coli respiration.

    PubMed Central

    Kumar, A M; Söll, D

    1992-01-01

    Glutamyl-tRNA reductase, encoded by the hemA gene, is the first enzyme in porphyrin biosynthesis in many organisms. Hemes, important porphyrin derivatives, are essential components of redox enzymes, such as cytochromes. Thus a hemA Escherichia coli strain (SASX41B) is deficient in cytochrome-mediated aerobic respiration. Upon complementation of this strain with an Arabidopsis thaliana cDNA library, we isolated a clone which permitted the SASX41B strain to grow aerobically. The clone encodes the gene for Arabidopsis alternative oxidase, whose deduced amino acid sequence was found to have 71% identity with that of the enzyme from the voodoo lily, Sauromatum guttatum. The Arabidopsis protein is expressed as a 31-kDa protein in E. coli and confers on this organism cyanide-resistant growth, which in turn is sensitive to salicylhydroxamate. This implies that a single polypeptide is sufficient for alternative oxidase activity. Based on these observations we propose that a cyanide-insensitive respiratory pathway operates in the transformed E. coli hemA strain. Introduction of this pathway now opens the way to genetic/molecular biological investigations of alternative oxidase and its cofactor. Images PMID:1438286

  15. Proton transfer in ba(3) cytochrome c oxidase from Thermus thermophilus.

    PubMed

    von Ballmoos, Christoph; Adelroth, Pia; Gennis, Robert B; Brzezinski, Peter

    2012-04-01

    The respiratory heme-copper oxidases catalyze reduction of O(2) to H(2)O, linking this process to transmembrane proton pumping. These oxidases have been classified according to the architecture, location and number of proton pathways. Most structural and functional studies to date have been performed on the A-class oxidases, which includes those that are found in the inner mitochondrial membrane and bacteria such as Rhodobacter sphaeroides and Paracoccus denitrificans (aa(3)-type oxidases in these bacteria). These oxidases pump protons with a stoichiometry of one proton per electron transferred to the catalytic site. The bacterial A-class oxidases use two proton pathways (denoted by letters D and K, respectively), for the transfer of protons to the catalytic site, and protons that are pumped across the membrane. The B-type oxidases such as, for example, the ba(3) oxidase from Thermus thermophilus, pump protons with a lower stoichiometry of 0.5 H(+)/electron and use only one proton pathway for the transfer of all protons. This pathway overlaps in space with the K pathway in the A class oxidases without showing any sequence homology though. Here, we review the functional properties of the A- and the B-class ba(3) oxidases with a focus on mechanisms of proton transfer and pumping.

  16. Respiratory papillomas

    PubMed Central

    Alagusundaramoorthy, Sayee Sundar; Agrawal, Abhinav

    2016-01-01

    Papillomas are known to occur in the lower respiratory tract. They are however, rare compared to their occurrence in the upper respiratory tract. These are generally exophytic tumors in the more proximal upper airways however cases with more distal location with an inverted growth pattern have also been described in the literature. These can be solitary or multiple and multifocality associated with multiple papillomas in the upper respiratory/aerodigestive tract. The four major types of respiratory papillomas are (1) Recurrent respiratory papillomas, (2) solitary squamous papillomas, (3) solitary glandular papillomas, (4) mixed papillomas. We review the incidence, etiopathology, diagnosis, and possible treatment modalities and algorithms for these respiratory papillomas. PMID:27625447

  17. Succinate oxidase in Neurospora.

    PubMed

    West, D J; Woodward, D O

    1973-02-01

    Two kinetically distinct states of succinate oxidase have been detected in the mitochondria of Neruospora crassa. One state has a K(m) for succinate of 4.1 x 10(-3)m, and the other has a K(m) for succinate of 3.5 x 10(-4)m. The high K(m) state was found in freshly extracted mitochondria from either 20- or 72-hr mycelium. However, the succinate oxidase activity in mitochondria from 20-hr mycelium rapidly deteriorated in vitro, leaving a stable residual activity with the lower K(m) for succinate. Adenosine triphosphate (ATP) plus Mg(2+) stabilized the high K(m) state in these preparations. The high K(m) state of succinate oxidase was further characterized by a two- to threefold increase in activity over the pH range 6.6 to 8.0 and by classical competitive inhibition by fumarate and malonate. By contrast, the low K(m) state of succinate oxidase showed a relatively flat response to pH over the range 6.6 to 8.0 and a nonclassical pattern of inhibition by fumarate and malonate, as shown by nonlinear plots of reciprocal velocity versus reciprocal substrate concentration in the presence of inhibitor or reciprocal velocity versus inhibitor concentration at fixed substrate concentrations. The relationship of mycelial age to the in vitro stability of succinate oxidase is considered with reference to probable changes in the relative pool sizes of extra- and intramitochondrial ATP in response to changes in the rate of glycolysis.

  18. Activation of the human neutrophil NADPH oxidase results in coupling of electron carrier function between ubiquinone-10 and cytochrome b559.

    PubMed

    Gabig, T G; Lefker, B A

    1985-04-10

    The enzymatic activity underlying the respiratory burst in human neutrophils was examined in a subcellular fraction with high specific activity and shown to be a membrane-associated complex of a flavoprotein, ubiquinone-10, and cytochrome b559 in an approximate 1.3:1:2 molar ratio. Study of the redox poise of these electron carriers indicated that electron flow in the intact complex from unstimulated cells proceeded: NADPH----E-FAD----ubiquinone-10. Similar studies on the complex prepared from stimulated neutrophils indicated that electron flow proceeded: NADPH----E-FAD----ubiquinone-10----cytochrome b559----oxygen. The active enzyme complex was inhibited by p-chloromercuribenzoate. Inhibition persisted after removal of excess inhibitor, was reversed by dithiothreitol, and could be blocked by prior addition of substrate (NADPH). Inhibition of the active oxidase complex by p-chloromercuribenzoate also inhibited electron flow from NADPH to all purported electron carriers in the chain (i.e. E-FAD, ubiquinone-10, and cytochrome b559). We conclude that activation of the oxidase enzyme complex in the intact neutrophil resulted in linkage of electron carrier function between endogenous ubiquinone-10 and cytochrome b559 and was without demonstrable effect on proximal electron flow. The p-chloromercuribenzoate sensitive site(s) proximal to the initial electron acceptor (E-FAD) did not appear to be altered by the cellular activation process.

  19. Spatiotemporal Production of Reactive Oxygen Species by NADPH Oxidase Is Critical for Tapetal Programmed Cell Death and Pollen Development in Arabidopsis[C][W

    PubMed Central

    Xie, Hong-Tao; Wan, Zhi-Yuan; Li, Sha; Zhang, Yan

    2014-01-01

    Male sterility in angiosperms has wide applications in agriculture, particularly in hybrid crop breeding and gene flow control. Microspores develop adjacent to the tapetum, a layer of cells that provides nutrients for pollen development and materials for pollen wall formation. Proper pollen development requires programmed cell death (PCD) of the tapetum, which requires transcriptional cascades and proteolytic enzymes. Reactive oxygen species (ROS) also affect tapetal PCD, and failures in ROS scavenging cause male sterility. However, many aspects of tapetal PCD remain unclear, including what sources generate ROS, whether ROS production has a temporal pattern, and how the ROS-producing system interacts with the tapetal transcriptional network. We report here that stage-specific expression of NADPH oxidases in the Arabidopsis thaliana tapetum contributes to a temporal peak of ROS production. Genetic interference with the temporal ROS pattern, by manipulating RESPIRATORY-BURST OXIDASE HOMOLOG (RBOH) genes, affected the timing of tapetal PCD and resulted in aborted male gametophytes. We further show that the tapetal transcriptional network regulates RBOH expression, indicating that the temporal pattern of ROS production intimately connects to other signaling pathways regulated by the tapetal transcriptional network to ensure the proper timing of tapetal PCD. PMID:24808050

  20. Type III burst pair

    NASA Astrophysics Data System (ADS)

    Ning, Zongjun; Fu, Qijun; Lu, Quankang

    2000-05-01

    We present a special solar radio burst detected on 5 January 1994 using the multi-channel (50) spectrometer (1.0-2.0 GHz) of the Beijing Astronomical Observatory (BAO). Sadly, the whole event could not be recorded since it had a broader bandwidth than the limit range of the instrument. The important part was obtained, however. The event is composed of a normal drift type III burst on the lower frequency side and a reverse drift type III burst appearing almost simultaneously on the high side. We call the burst type III a burst pair. It is a typical characteristic of two type III bursts that they are morphologically symmetric about some frequency from 1.64 GHz to 1.78 GHz on the dynamic spectra records, which indicates that there are two different electron beams from the same acceleration region travelling simultaneously in opposite directions (upward and downward). A magnetic reconnection mode is a nice interpretation of type III burst pair since the plasma beta β~=0.01 is much less than 1 and the beams have velocity of about 1.07×10^8 cm s^-1 after leaving the reconnection region if we assume that the ambient magnetic field strength is about 100 G.

  1. Type III burst pair.

    NASA Astrophysics Data System (ADS)

    Zongjun, Ning; Fu, Qijun; Quankang, Lu

    2000-05-01

    Presents a special solar radio burst detected on 5 January 1994 using the multi-channel (50) spectrometer (1.0 - 2.0 GHz) of the Beijing Astronomical Observatory. Sadly, the whole event could not be recorded since it had a broader bandwidth than the limit range of the instrument. The important part was obtained, however. The event is composed of a normal drift type III burst on the lower frequency side and a reverse drift type III burst appearing almost simultaneously on the high side. The authors call the burst type III a burst pair. It is a typical characteristic of two type III bursts that they are morphologically symmetric about some frequency from 1.64 GHz to 1.78 GHz on the dynamic spectra records, which indicates that there are two different electron beams from the same acceleration region travelling simultaneously in opposite directions (upward and downward). A magnetic reconnection mode is an interpretation of type III burst pair.

  2. Purification and characterization of the cytochrome c oxidase from Rhodopseudomonas sphaeroides.

    PubMed

    Gennis, R B; Casey, R P; Azzi, A; Ludwig, B

    1982-06-15

    When grown aerobically in the dark, Rhodopseudomonas sphaeroides develops a respiratory chain similar to that in mitochondria and the photosynthetic apparatus is suppressed. The aa3-type cytochrome c oxidase from Rps. sphaeroides has been purified in Triton X-100 by affinity chromatography with Sepharose 4B coupled to yeast cytochrome c. The oxidase contains 14 nmol heme a/mg protein and is composed of three polypeptide subunits with relative molecular masses of 45000, 37000 and 35000. The enzyme is highly active in the presence of detergents, with a maximal velocity of 300 s-1/mol oxidase using either yeast or horse-heart cytochrome c. The Rps. sphaeroides oxidase is cross-reactive with antibodies directed against the oxidases from Paracoccus denitrificans and Saccharomyces cerevisiae. A particularly close relationship is indicated in the case of P. denitrificans. The Rps. sphaeroides oxidase has been incorporated into phospholipid vesicles. The resulting oxidase in these vesicles demonstrates high enzymatic activity and a respiratory control ratio of 5. Using these vesicles, no evidence for proton extrusion accompanying cytochrome c oxidation was observed. The data suggest that the Rps. sphaeroides oxidase does not function as a proton pump.

  3. Theta-Burst LTP

    PubMed Central

    Larson, John; Munkácsy, Erin

    2014-01-01

    This review covers the spatial and temporal rules governing induction of hippocampal long-term potentiation (LTP) by theta-burst stimulation. Induction of LTP in field CA1 by high frequency stimulation bursts that resemble the burst discharges (complex-spikes) of hippocampal pyramidal neurons involves a multiple-step mechanism. A single burst is insufficient for LTP induction because it evokes both excitatory and inhibitory currents that partially cancel and limit postsynaptic depolarization. Bursts repeated at the frequency (~5 Hz) of the endogenous theta rhythm induce maximal LTP, primarily because this frequency disables feed-forward inhibition and allows sufficient postsynaptic depolarization to activate voltage-sensitive NMDA receptors. The disinhibitory process, referred to as “priming”, involves presynaptic GABA autoreceptors that inhibit GABA release. Activation of NMDA receptors allows a calcium flux into dendritic spines that serves as the proximal trigger for LTP. We include new data showing that theta-burst stimulation is more efficient than other forms of stimulation for LTP induction. In addityion, we demonstrate that associative interactions between synapses activated during theta-bursts are limited to major dendritic domains since such interactions occur within apical or basal dendritic trees but not between them. We review evidence that recordings of electrophysiological responses during theta burst stimulation can help to determine if experimental manipulations that affect LTP do so by affecting events antecedent to the induction process, such as NMDA receptor activation, or downstream signaling cascades that result from postsynaptic calcium fluxes. Finally, we argue that theta-burst LTP represents a minimal model for stable, non-decremental LTP that is more sensitive to a variety of experimental manipulations than is LTP induced by other stimulation paradigms. PMID:25452022

  4. Respiratory Failure

    MedlinePlus

    Respiratory failure happens when not enough oxygen passes from your lungs into your blood. Your body's organs, ... brain, need oxygen-rich blood to work well. Respiratory failure also can happen if your lungs can' ...

  5. Respiratory system

    NASA Technical Reports Server (NTRS)

    Bartlett, R. G., Jr.

    1973-01-01

    The general anatomy and function of the human respiratory system is summarized. Breathing movements, control of breathing, lung volumes and capacities, mechanical relations, and factors relevant to respiratory support and equipment design are discussed.

  6. On vortex bursting

    NASA Technical Reports Server (NTRS)

    Werle, H.

    1984-01-01

    Vortex bursting is studied by means of visualization. The physical behavior of the phenomenon is emphasized, and its similarity with boundary layer separation or wake bursting becomes apparent. The essential influence of an increasing pressure gradient on the initiation, the position and the type of bursting is clearly confirmed. The evolution of the phenomena as a function of several parameters is analyzed in the case of delta wings, alone or installed on aircraft models, and compared with the results of similar wind tunnel or flight tests.

  7. Expression of alternative oxidase in Drosophila ameliorates diverse phenotypes due to cytochrome oxidase deficiency.

    PubMed

    Kemppainen, Kia K; Rinne, Juho; Sriram, Ashwin; Lakanmaa, Matti; Zeb, Akbar; Tuomela, Tea; Popplestone, Anna; Singh, Satpal; Sanz, Alberto; Rustin, Pierre; Jacobs, Howard T

    2014-04-15

    Mitochondrial dysfunction is a significant factor in human disease, ranging from systemic disorders of childhood to cardiomyopathy, ischaemia and neurodegeneration. Cytochrome oxidase, the terminal enzyme of the mitochondrial respiratory chain, is a frequent target. Lower eukaryotes possess alternative respiratory-chain enzymes that provide non-proton-translocating bypasses for respiratory complexes I (single-subunit reduced nicotinamide adenine dinucleotide dehydrogenases, e.g. Ndi1 from yeast) or III + IV [alternative oxidase (AOX)], under conditions of respiratory stress or overload. In previous studies, it was shown that transfer of yeast Ndi1 or Ciona intestinalis AOX to Drosophila was able to overcome the lethality produced by toxins or partial knockdown of complex I or IV. Here, we show that AOX can provide a complete or substantial rescue of a range of phenotypes induced by global or tissue-specific knockdown of different cIV subunits, including integral subunits required for catalysis, as well as peripheral subunits required for multimerization and assembly. AOX was also able to overcome the pupal lethality produced by muscle-specific knockdown of subunit CoVb, although the rescued flies were short lived and had a motility defect. cIV knockdown in neurons was not lethal during development but produced a rapidly progressing locomotor and seizure-sensitivity phenotype, which was substantially alleviated by AOX. Expression of Ndi1 exacerbated the neuronal phenotype produced by cIV knockdown. Ndi1 expressed in place of essential cI subunits produced a distinct residual phenotype of delayed development, bang sensitivity and male sterility. These findings confirm the potential utility of alternative respiratory chain enzymes as tools to combat mitochondrial disease, while indicating important limitations thereof.

  8. Respiratory alkalosis

    MedlinePlus

    ... shortness of breath. Alternative Names Alkalosis - respiratory Images Respiratory system References Effros RM, Swenson ER. Acid-base balance. In: Broaddus VC, Mason RJ, Ernst JD, et al, eds. Murray and Nadel's Textbook of Respiratory Medicine . 6th ed. Philadelphia, PA: Elsevier Saunders; 2016: ...

  9. Induction of reactive oxygen species and the potential role of NADPH oxidase in hyperhydricity of garlic plantlets in vitro.

    PubMed

    Tian, Jie; Cheng, Yaqi; Kong, Xiangyu; Liu, Min; Jiang, Fangling; Wu, Zhen

    2017-01-01

    Hyperhydricity is a physiological disorder associated with oxidative stress. Reactive oxygen species (ROS) generation in plants is initiated by various enzymatic sources, including plasma membrane-localized nicotinamide adenine dinucleotide phosphate (NADPH) oxidases, cell wall-bound peroxidase (POD), and apoplastic polyamine oxidase (PAO). The origin of the oxidative burst associated with hyperhydricity remains unknown. To investigate the role of NADPH oxidases, POD, and PAO in ROS production and hyperhydricity, exogenous hydrogen peroxide (H2O2) and inhibitors of each ROS-producing enzyme were applied to explore the mechanism of oxidative stress induction in garlic plantlets in vitro. A concentration of 1.5 mM H2O2 increased endogenous ROS production and hyperhydricity occurrence and enhanced the activities of NADPH oxidases, POD, and PAO. During the entire treatment period, NADPH oxidase activity increased continuously, whereas POD and PAO activities exhibited a transient increase and subsequently declined. Histochemical and cytochemical visualization demonstrated that specific inhibitors of each enzyme effectively suppressed ROS accumulation. Moreover, superoxide anion generation, H2O2 content, and hyperhydric shoot frequency in H2O2-stressed plantlets decreased significantly. The NADPH oxidase inhibitor was the most effective at suppressing superoxide anion production. The results suggested that NADPH oxidases, POD, and PAO were responsible for endogenous ROS induction. NADPH oxidase activation might play a pivotal role in the oxidative burst in garlic plantlets in vitro during hyperhydricity.

  10. INTEGRAL burst alert service

    NASA Technical Reports Server (NTRS)

    Pedersen, H.; Jennings, D.; Mereghetti, S.; Teegarden, B.

    1997-01-01

    The detection, accurate positioning, and spectral analysis of cosmic gamma ray bursts is an objective of the International Gamma Ray Astrophysics Laboratory (INTEGRAL) mission. Due to their unpredictable nature, gamma ray bursts can only be observed in serendipity mode. In order to allow and promote multiwavelength follow-up observations of such events, it is desirable to make the information available to the astrophysics community with a minimum delay through the use of Internet. Ideally, the data dissemination should occur within a few seconds of the start of the burst event so that follow up observations can proceed while gamma rays are still being emitted. The technical feasibility of building such a system to disseminate INTEGRAL burst alerts in real time is currently under consideration, the preliminary results of which are presented. It is concluded that such an alert service is technically feasible.

  11. GLAST's GBM Burst Trigger

    NASA Technical Reports Server (NTRS)

    Band, D.; Briggs, M.; Connaughton, V.; Kippen, M.; Preece, R.

    2003-01-01

    The GLAST Burst Monitor (GBM) will detect and localize bursts for the GLAST mission, and provide the spectral and temporal context in the traditional 10 keV to 25 MeV band for the high energy observations by the Large Area Telescope (LAT). The GBM will use traditional rate triggers in up to three energy bands, and on a variety of timescales between 16 ms and 16 s.

  12. The proton pump of heme-copper oxidases.

    PubMed

    Papa, S; Capitanio, N; Glaser, P; Villani, G

    1994-05-01

    Proton pumping heme-copper oxidases represent the terminal, energy-transfer enzymes of respiratory chains in prokaryotes and eukaryotes. The CuB-heme a3 (or heme o) binuclear center, associated with the largest subunit I of cytochrome c and quinol oxidases, is directly involved in the coupling between dioxygen reduction and proton pumping. The role of the other subunits is less clear. The following aspects will be covered in this paper: i) the efficiency of coupling in the mitochondrial aa3 cytochrome c oxidase. In particular, the effect of respiratory rate and protonmotive force on the H+/e- stoichiometry and the role of subunit IV; ii) mutational analysis of the aa3 quinol oxidase of Bacillus subtilis addressed to the role of subunit III, subunit IV and specific residues in subunit I; iii) possible models of the protonmotive catalytic cycle at the binuclear center. The observations available suggest that H+/e- coupling is based on the combination of protonmotive redox catalysis at the binuclear center and co-operative proton transfer in the protein.

  13. A mutant of Pseudomonas aeruginosa that lacks c-type cytochromes has a functional cyanide-insensitive oxidase.

    PubMed

    Ray, A; Williams, H D

    1996-01-01

    Using transposon mutagenesis and screening for the loss of the ability to oxidise the artificial electron donor N,N,N',N'-tetramethyl-p-phenylenediamine, we have isolated a mutant of Pseudomonas aeruginosa that lacks all c-type cytochromes. This mutant is unable to grow anaerobically with nitrate as a terminal electron acceptor. Analysis of its respiratory function indicates that the mutant has lost its cytochrome c oxidase-terminated respiratory pathway but the cyanide-insensitive oxidase-terminated branch remains functional. Complementation of the mutant by in vivo cloning led to recovery of the wild-type characteristics. These data are consistent with the idea that the cyanide-insensitive respiratory pathway does not contain haem c and that the pathway's terminal oxidase is a quinol oxidase.

  14. Respiratory alkalosis.

    PubMed

    Foster, G T; Vaziri, N D; Sassoon, C S

    2001-04-01

    Respiratory alkalosis is an extremely common and complicated problem affecting virtually every organ system in the body. This article reviews the various facets of this interesting problem. Respiratory alkalosis produces multiple metabolic abnormalities, from changes in potassium, phosphate, and calcium, to the development of a mild lactic acidosis. Renal handling of the above ions is also affected. The etiologies may be related to pulmonary or extrapulmonary disorders. Hyperventilation syndrome is a common etiology of respiratory alkalosis in the emergency department setting and is a diagnosis by exclusion. There are many cardiac effects of respiratory alkalosis, such as tachycardia, ventricular and atrial arrhythmias, and ischemic and nonischemic chest pain. In the lungs, vasodilation occurs, and in the gastrointestinal system there are changes in perfusion, motility, and electrolyte handling. Therapeutically, respiratory alkalosis is used for treatment of elevated intracranial pressure. Correction of a respiratory alkalosis is best performed by correcting the underlying etiology.

  15. Cytochrome c oxidase-intermediate fibres: importance in understanding the pathogenesis and treatment of mitochondrial myopathy.

    PubMed

    Murphy, Julie L; Ratnaike, Thiloka E; Shang, Ersong; Falkous, Gavin; Blakely, Emma L; Alston, Charlotte L; Taivassalo, Tanja; Haller, Ronald G; Taylor, Robert W; Turnbull, Doug M

    2012-08-01

    An important diagnostic muscle biopsy finding in patients with mitochondrial DNA disease is the presence of respiratory-chain deficient fibres. These fibres are detected as cytochrome c oxidase-deficient following a sequential cytochrome c oxidase-succinate dehydrogenase reaction, often in a mosaic pattern within a population of cytochrome c oxidase-normal fibres. Detailed analysis of muscle biopsies from patients with various mitochondrial DNA defects shows that a spectrum of deficiency exists, as there are a large number of fibres which do not correspond to being either completely cytochrome c oxidase-normal (brown staining) or cytochrome c oxidase-deficient (blue staining). We have used a combination of histochemical and immunocytochemical techniques to show that a population of cytochrome c oxidase-intermediate reacting fibres are a gradation between normal and deficient fibres. We show that cytochrome c oxidase-intermediate fibres also have different genetic characteristics in terms of amount of mutated and wild-type mtDNA, and as such, may represent an important transition between respiratory normal and deficient fibres. Assessing changes in intermediate fibres will be crucial to evaluating the responses to treatment and in particular to exercise training regimes in patients with mitochondrial DNA disease.

  16. A Burst to See

    NASA Astrophysics Data System (ADS)

    2008-04-01

    On 19 March, Nature was particularly generous and provided astronomers with the wealth of four gamma-ray bursts on the same day. But that was not all: one of them is the most luminous object ever observed in the Universe. Despite being located in a distant galaxy, billions of light years away, it was so bright that it could have been seen, for a brief while, with the unaided eye. ESO PR Photo 08a/08 ESO PR Photo 08a/08 The REM Telescope and TORTORA Camera Gamma-ray bursts (GRBs) are short flashes of energetic gamma-rays lasting from less than a second to several minutes. They release a tremendous quantity of energy in this short time making them the most powerful events since the Big Bang. It is now widely accepted that the majority of the gamma-ray bursts signal the explosion of very massive, highly evolved stars that collapse into black holes. Gamma-ray bursts, which are invisible to our eyes, are discovered by telescopes in space. After releasing their intense burst of high-energy radiation, they become detectable for a short while in the optical and in the near-infrared. This 'afterglow' fades very rapidly, making detailed analysis possible for only a few hours after the gamma-ray detection. This analysis is important in particular in order to determine the GRB's distance and, hence, intrinsic brightness. The gamma-ray burst GRB 080319B was detected by the NASA/STFC/ASI Swift satellite. "It was so bright that it almost blinded the Swift instruments for a while," says Guido Chincarini, Italian principal investigator of the mission. A bright optical counterpart was soon identified in the Boötes Constellation (the "Bear Driver" or "Herdsman"). A host of ground-based telescopes reacted promptly to study this new object in the sky. In particular, the optical emission was detected by a few wide-field cameras on telescopes that constantly monitor a large fraction of the sky, including the TORTORA camera in symbiosis with the 0.6-m REM telescope located at La Silla

  17. Fast Radio Bursts

    NASA Astrophysics Data System (ADS)

    Kaspi, Victoria M.

    2017-01-01

    Fast Radio Bursts (FRBs) are a recently discovered phenomenon consisting of short (few ms) bursts of radio waves that have dispersion measures that strongly suggest an extragalactic and possibly cosmological origin. Current best estimates for the rate of FRBs is several thousand per sky per day at radio frequencies near 1.4 GHz. Even with so high a rate, to date, fewer than 20 FRBs have been reported, with one source showing repeated bursts. In this talk I will describe known FRB properties including what is known about the lone repeating source, as well as models for the origin of these mysterious events. I will also describe the CHIME radio telescope, currently under construction in Canada. Thanks to its great sensitivity and unprecedented field-of-view, CHIME promises major progress on FRBs.

  18. The Glast Burst Monitor

    NASA Technical Reports Server (NTRS)

    Meegan, Charles

    2000-01-01

    The Gamma-Ray Large Area Space Telescope (GLAST) will include a secondary instrument to augment the observatory's capabilities for GRB studies. The GLAST Burst Monitor (GBK is a collaboration between Marshall Space Flight Center, the University of Huntsville, Alabama, and the Max Plank Institute for Extraterrestrial Physics. The purpose of the GBM is to extend energy coverage below the main instrument's lower limit of about 20 MeV, and to provide an on-board burst trigger and approximate location. The instrument consists of twelve NaI detectors and two BGO detectors. This combination provides energy coverage from a few keV up to about 30 MeV.

  19. Interplanetary Type IV Bursts

    NASA Astrophysics Data System (ADS)

    Hillaris, A.; Bouratzis, C.; Nindos, A.

    2016-08-01

    We study the characteristics of moving type IV radio bursts that extend to hectometric wavelengths (interplanetary type IV or type {IV}_{{IP}} bursts) and their relationship with energetic phenomena on the Sun. Our dataset comprises 48 interplanetary type IV bursts observed with the Radio and Plasma Wave Investigation (WAVES) instrument onboard Wind in the 13.825 MHz - 20 kHz frequency range. The dynamic spectra of the Radio Solar Telescope Network (RSTN), the Nançay Decametric Array (DAM), the Appareil de Routine pour le Traitement et l' Enregistrement Magnetique de l' Information Spectral (ARTEMIS-IV), the Culgoora, Hiraso, and the Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation (IZMIRAN) Radio Spectrographs were used to track the evolution of the events in the low corona. These were supplemented with soft X-ray (SXR) flux-measurements from the Geostationary Operational Environmental Satellite (GOES) and coronal mass ejections (CME) data from the Large Angle and Spectroscopic Coronagraph (LASCO) onboard the Solar and Heliospheric Observatory (SOHO). Positional information of the coronal bursts was obtained by the Nançay Radioheliograph (NRH). We examined the relationship of the type IV events with coronal radio bursts, CMEs, and SXR flares. The majority of the events (45) were characterized as compact, their duration was on average 106 minutes. This type of events was, mostly, associated with M- and X-class flares (40 out of 45) and fast CMEs, 32 of these events had CMEs faster than 1000 km s^{-1}. Furthermore, in 43 compact events the CME was possibly subjected to reduced aerodynamic drag as it was propagating in the wake of a previous CME. A minority (three) of long-lived type {IV}_{{IP}} bursts was detected, with durations from 960 minutes to 115 hours. These events are referred to as extended or long duration and appear to replenish their energetic electron content, possibly from electrons escaping from the corresponding coronal

  20. The oxidative burst reaction in mammalian cells depends on gravity.

    PubMed

    Adrian, Astrid; Schoppmann, Kathrin; Sromicki, Juri; Brungs, Sonja; von der Wiesche, Melanie; Hock, Bertold; Kolanus, Waldemar; Hemmersbach, Ruth; Ullrich, Oliver

    2013-12-20

    Gravity has been a constant force throughout the Earth's evolutionary history. Thus, one of the fundamental biological questions is if and how complex cellular and molecular functions of life on Earth require gravity. In this study, we investigated the influence of gravity on the oxidative burst reaction in macrophages, one of the key elements in innate immune response and cellular signaling. An important step is the production of superoxide by the NADPH oxidase, which is rapidly converted to H2O2 by spontaneous and enzymatic dismutation. The phagozytosis-mediated oxidative burst under altered gravity conditions was studied in NR8383 rat alveolar macrophages by means of a luminol assay. Ground-based experiments in "functional weightlessness" were performed using a 2 D clinostat combined with a photomultiplier (PMT clinostat). The same technical set-up was used during the 13th DLR and 51st ESA parabolic flight campaign. Furthermore, hypergravity conditions were provided by using the Multi-Sample Incubation Centrifuge (MuSIC) and the Short Arm Human Centrifuge (SAHC). The results demonstrate that release of reactive oxygen species (ROS) during the oxidative burst reaction depends greatly on gravity conditions. ROS release is 1.) reduced in microgravity, 2.) enhanced in hypergravity and 3.) responds rapidly and reversible to altered gravity within seconds. We substantiated the effect of altered gravity on oxidative burst reaction in two independent experimental systems, parabolic flights and 2D clinostat / centrifuge experiments. Furthermore, the results obtained in simulated microgravity (2D clinorotation experiments) were proven by experiments in real microgravity as in both cases a pronounced reduction in ROS was observed. Our experiments indicate that gravity-sensitive steps are located both in the initial activation pathways and in the final oxidative burst reaction itself, which could be explained by the role of cytoskeletal dynamics in the assembly and function

  1. The oxidative burst reaction in mammalian cells depends on gravity

    PubMed Central

    2013-01-01

    Gravity has been a constant force throughout the Earth’s evolutionary history. Thus, one of the fundamental biological questions is if and how complex cellular and molecular functions of life on Earth require gravity. In this study, we investigated the influence of gravity on the oxidative burst reaction in macrophages, one of the key elements in innate immune response and cellular signaling. An important step is the production of superoxide by the NADPH oxidase, which is rapidly converted to H2O2 by spontaneous and enzymatic dismutation. The phagozytosis-mediated oxidative burst under altered gravity conditions was studied in NR8383 rat alveolar macrophages by means of a luminol assay. Ground-based experiments in “functional weightlessness” were performed using a 2 D clinostat combined with a photomultiplier (PMT clinostat). The same technical set-up was used during the 13th DLR and 51st ESA parabolic flight campaign. Furthermore, hypergravity conditions were provided by using the Multi-Sample Incubation Centrifuge (MuSIC) and the Short Arm Human Centrifuge (SAHC). The results demonstrate that release of reactive oxygen species (ROS) during the oxidative burst reaction depends greatly on gravity conditions. ROS release is 1.) reduced in microgravity, 2.) enhanced in hypergravity and 3.) responds rapidly and reversible to altered gravity within seconds. We substantiated the effect of altered gravity on oxidative burst reaction in two independent experimental systems, parabolic flights and 2D clinostat / centrifuge experiments. Furthermore, the results obtained in simulated microgravity (2D clinorotation experiments) were proven by experiments in real microgravity as in both cases a pronounced reduction in ROS was observed. Our experiments indicate that gravity-sensitive steps are located both in the initial activation pathways and in the final oxidative burst reaction itself, which could be explained by the role of cytoskeletal dynamics in the assembly and

  2. The GLAST Burst Monitor

    NASA Technical Reports Server (NTRS)

    Meegan, Charles A.

    2004-01-01

    The Gamma Ray Large Area Space Telescope (GLAST) observatory, scheduled for launch in 2007, comprises the Large Area Telescope (LAT) and the GLAST Burst Monitor (GBM). spectral changes that are known to occur within GRBs. between the NASA Marshall Space Flight Center, the University of Alabama in Huntsville, and the Max Planck Institute for Extraterrestrial Physics. It consists of an array of NaI and BGO scintillation detectors operating in the 10 kev to 25 MeV range. The field of view includes the entire unocculted sky when the observatory is pointing close to the zenith. The GBM will enhance LAT observations of GRBs by extending the spectral coverage into the range of current GRB databases, and will provide a trigger for reorienting the spacecraft to observe delayed emission from bursts outside the LAT field of view. GBM is expected to trigger on about 200 bursts per year, and will provide on-board locations of strong bursts accurate to better than 10 degrees.

  3. The Double Firing Burst

    NASA Astrophysics Data System (ADS)

    2008-09-01

    Astronomers from around the world combined data from ground- and space-based telescopes to paint a detailed portrait of the brightest explosion ever seen. The observations reveal that the jets of the gamma-ray burst called GRB 080319B were aimed almost directly at the Earth. Uncovering the disc ESO PR Photo 28/08 A Gamma-Ray Burst with Two Jets Read more on this illuminating blast in the additional story. GRB 080319B was so intense that, despite happening halfway across the Universe, it could have been seen briefly with the unaided eye (ESO 08/08). In a paper to appear in the 11 September issue of Nature, Judith Racusin of Penn State University, Pennsylvania (USA), and a team of 92 co-authors report observations across the electromagnetic spectrum that began 30 minutes before the explosion and followed it for months afterwards. "We conclude that the burst's extraordinary brightness arose from a jet that shot material almost directly towards Earth at almost the speed of light - the difference is only 1 part in 20 000," says Guido Chincarini, a member of the team. Gamma-ray bursts are the Universe's most luminous explosions. Most occur when massive stars run out of fuel. As a star collapses, it creates a black hole or neutron star that, through processes not fully understood, drives powerful gas jets outward. As the jets shoot into space, they strike gas previously shed by the star and heat it, thereby generating bright afterglows. The team believes the jet directed toward Earth contained an ultra-fast component just 0.4 degrees across (this is slightly smaller than the apparent size of the Full Moon). This jet is contained within another slightly less energetic jet about 20 times wider. The broad component is more typical of other bursts. "Perhaps every gamma-ray burst has a narrow jet, but astronomers miss it most of the time," says team member Stefano Covino. "We happened to view this monster down the barrel of the very narrow and energetic jet, and the chance for

  4. Alternative oxidase: distribution, induction, properties, structure, regulation, and functions.

    PubMed

    Rogov, A G; Sukhanova, E I; Uralskaya, L A; Aliverdieva, D A; Zvyagilskaya, R A

    2014-12-01

    The respiratory chain in the majority of organisms with aerobic type metabolism features the concomitant existence of the phosphorylating cytochrome pathway and the cyanide- and antimycin A-insensitive oxidative route comprising a so-called alternative oxidase (AOX) as a terminal oxidase. In this review, the history of AOX discovery is described. Considerable evidence is presented that AOX occurs widely in organisms at various levels of organization and is not confined to the plant kingdom. This enzyme has not been found only in Archaea, mammals, some yeasts and protists. Bioinformatics research revealed the sequences characteristic of AOX in representatives of various taxonomic groups. Based on multiple alignments of these sequences, a phylogenetic tree was constructed to infer their possible evolution. The ways of AOX activation, as well as regulatory interactions between AOX and the main respiratory chain are described. Data are summarized concerning the properties of AOX and the AOX-encoding genes whose expression is either constitutive or induced by various factors. Information is presented on the structure of AOX, its active center, and the ubiquinone-binding site. The principal functions of AOX are analyzed, including the cases of cell survival, optimization of respiratory metabolism, protection against excess of reactive oxygen species, and adaptation to variable nutrition sources and to biotic and abiotic stress factors. It is emphasized that different AOX functions complement each other in many instances and are not mutually exclusive. Examples are given to demonstrate that AOX is an important tool to overcome the adverse aftereffects of restricted activity of the main respiratory chain in cells and whole animals. This is the first comprehensive review on alternative oxidases of various organisms ranging from yeasts and protists to vascular plants.

  5. Burst Populations and Detector Sensitivity

    NASA Technical Reports Server (NTRS)

    Band, David L.

    2003-01-01

    The F(sub T) (peak bolometric photon flux) vs. E(sub p) (peak energy) plane is a powerful tool to compare the burst populations detected by different detectors. Detector sensitivity curves in this plane demonstrate which burst populations the detectors will detect. For example, future CZT-based detectors will show the largest increase in sensitivity for soft bursts, and will be particularly well- suited to study X-ray rich bursts and X-ray Flashes. Identical bursts at different redshifts describe a track in the F(sub T)-E(sub p) plane.

  6. A repeating fast radio burst

    NASA Astrophysics Data System (ADS)

    Spitler, L. G.; Scholz, P.; Hessels, J. W. T.; Bogdanov, S.; Brazier, A.; Camilo, F.; Chatterjee, S.; Cordes, J. M.; Crawford, F.; Deneva, J.; Ferdman, R. D.; Freire, P. C. C.; Kaspi, V. M.; Lazarus, P.; Lynch, R.; Madsen, E. C.; McLaughlin, M. A.; Patel, C.; Ransom, S. M.; Seymour, A.; Stairs, I. H.; Stappers, B. W.; van Leeuwen, J.; Zhu, W. W.

    2016-03-01

    Fast radio bursts are millisecond-duration astronomical radio pulses of unknown physical origin that appear to come from extragalactic distances. Previous follow-up observations have failed to find additional bursts at the same dispersion measure (that is, the integrated column density of free electrons between source and telescope) and sky position as the original detections. The apparent non-repeating nature of these bursts has led to the suggestion that they originate in cataclysmic events. Here we report observations of ten additional bursts from the direction of the fast radio burst FRB 121102. These bursts have dispersion measures and sky positions consistent with the original burst. This unambiguously identifies FRB 121102 as repeating and demonstrates that its source survives the energetic events that cause the bursts. Additionally, the bursts from FRB 121102 show a wide range of spectral shapes that appear to be predominantly intrinsic to the source and which vary on timescales of minutes or less. Although there may be multiple physical origins for the population of fast radio bursts, these repeat bursts with high dispersion measure and variable spectra specifically seen from the direction of FRB 121102 support an origin in a young, highly magnetized, extragalactic neutron star.

  7. A repeating fast radio burst.

    PubMed

    Spitler, L G; Scholz, P; Hessels, J W T; Bogdanov, S; Brazier, A; Camilo, F; Chatterjee, S; Cordes, J M; Crawford, F; Deneva, J; Ferdman, R D; Freire, P C C; Kaspi, V M; Lazarus, P; Lynch, R; Madsen, E C; McLaughlin, M A; Patel, C; Ransom, S M; Seymour, A; Stairs, I H; Stappers, B W; van Leeuwen, J; Zhu, W W

    2016-03-10

    Fast radio bursts are millisecond-duration astronomical radio pulses of unknown physical origin that appear to come from extragalactic distances. Previous follow-up observations have failed to find additional bursts at the same dispersion measure (that is, the integrated column density of free electrons between source and telescope) and sky position as the original detections. The apparent non-repeating nature of these bursts has led to the suggestion that they originate in cataclysmic events. Here we report observations of ten additional bursts from the direction of the fast radio burst FRB 121102. These bursts have dispersion measures and sky positions consistent with the original burst. This unambiguously identifies FRB 121102 as repeating and demonstrates that its source survives the energetic events that cause the bursts. Additionally, the bursts from FRB 121102 show a wide range of spectral shapes that appear to be predominantly intrinsic to the source and which vary on timescales of minutes or less. Although there may be multiple physical origins for the population of fast radio bursts, these repeat bursts with high dispersion measure and variable spectra specifically seen from the direction of FRB 121102 support an origin in a young, highly magnetized, extragalactic neutron star.

  8. Respiratory Therapists

    MedlinePlus

    ... programs typically include courses in human anatomy and physiology, chemistry, physics, microbiology, pharmacology, and math. Other courses ... and math skills. Respiratory therapists must understand anatomy, physiology, and other sciences and be able to calculate ...

  9. Jovian type III radio bursts

    NASA Technical Reports Server (NTRS)

    Kurth, W. S.; Gurnett, D. A.; Scarf, F. L.

    1989-01-01

    Radio bursts have been observed in the Voyager plasma wave data from Jupiter that bear a striking resemblance to solar type III radio bursts. The emissions lie in the frequency range near 10 kHz, have durations of a minute or so, and occur in a set of periodically spaced bursts. The spacing between primary bursts is typically 15 min, but the bursts may have additional components which recur on time scales of about 3 min. The similarity with solar type III radio bursts suggests a source mechanism involving the movement of energetic electrons through a density gradient in the plasma surrounding Jupiter. The periodicity of bursts suggests Io may be involved in the generation of waves, since the timing is similar to the Alfven wave travel time from one hemisphere to the other through the Io torus.

  10. Regulation and Function of Versatile Aerobic and Anaerobic Respiratory Metabolism in Pseudomonas aeruginosa

    PubMed Central

    Arai, Hiroyuki

    2011-01-01

    Pseudomonas aeruginosa is a ubiquitously distributed opportunistic pathogen that inhabits soil and water as well as animal-, human-, and plant-host-associated environments. The ubiquity would be attributed to its very versatile energy metabolism. P. aeruginosa has a highly branched respiratory chain terminated by multiple terminal oxidases and denitrification enzymes. Five terminal oxidases for aerobic respiration have been identified in the P. aeruginosa cells. Three of them, the cbb3-1 oxidase, the cbb3-2 oxidase, and the aa3 oxidase, are cytochrome c oxidases and the other two, the bo3 oxidase and the cyanide-insensitive oxidase, are quinol oxidases. Each oxidase has a specific affinity for oxygen, efficiency of energy coupling, and tolerance to various stresses such as cyanide and reactive nitrogen species. These terminal oxidases are used differentially according to the environmental conditions. P. aeruginosa also has a complete set of the denitrification enzymes that reduce nitrate to molecular nitrogen via nitrite, nitric oxide (NO), and nitrous oxide. These nitrogen oxides function as alternative electron acceptors and enable P. aeruginosa to grow under anaerobic conditions. One of the denitrification enzymes, NO reductase, is also expected to function for detoxification of NO produced by the host immune defense system. The control of the expression of these aerobic and anaerobic respiratory enzymes would contribute to the adaptation of P. aeruginosa to a wide range of environmental conditions including in the infected hosts. Characteristics of these respiratory enzymes and the regulatory system that controls the expression of the respiratory genes in the P. aeruginosa cells are overviewed in this article. PMID:21833336

  11. Respiratory arsenate reductase as a bidirectional enzyme

    USGS Publications Warehouse

    Richey, C.; Chovanec, P.; Hoeft, S.E.; Oremland, R.S.; Basu, P.; Stolz, J.F.

    2009-01-01

    The haloalkaliphilic bacterium Alkalilimnicola ehrlichii is capable of anaerobic chemolithoautotrophic growth by coupling the oxidation of arsenite (As(III)) to the reduction of nitrate and carbon dioxide. Analysis of its complete genome indicates that it lacks a conventional arsenite oxidase (Aox), but instead possesses two operons that each encode a putative respiratory arsenate reductase (Arr). Here we show that one homolog is expressed under chemolithoautotrophic conditions and exhibits both arsenite oxidase and arsenate reductase activity. We also demonstrate that Arr from two arsenate respiring bacteria, Alkaliphilus oremlandii and Shewanella sp. strain ANA-3, is also biochemically reversible. Thus Arr can function as a reductase or oxidase. Its physiological role in a specific organism, however, may depend on the electron potentials of the molybdenum center and [Fe–S] clusters, additional subunits, or constitution of the electron transfer chain. This versatility further underscores the ubiquity and antiquity of microbial arsenic metabolism.

  12. Pathophysiology and Treatments of Oxidative Injury in Ischemic Stroke: Focus on the Phagocytic NADPH Oxidase 2

    PubMed Central

    Carbone, Federico; Teixeira, Priscila Camillo; Braunersreuther, Vincent; Mach, François; Vuilleumier, Nicolas

    2015-01-01

    Abstract Significance: Phagocytes play a key role in promoting the oxidative stress after ischemic stroke occurrence. The phagocytic NADPH oxidase (NOX) 2 is a membrane-bound enzyme complex involved in the antimicrobial respiratory burst and free radical production in these cells. Recent Advances: Different oxidants have been shown to induce opposite effects on neuronal homeostasis after a stroke. However, several experimental models support the detrimental effects of NOX activity (especially the phagocytic isoform) on brain recovery after stroke. Therapeutic strategies selectively targeting the neurotoxic ROS and increasing neuroprotective oxidants have recently produced promising results. Critical Issues: NOX2 might promote carotid plaque rupture and stroke occurrence. In addition, NOX2-derived reactive oxygen species (ROS) released by resident and recruited phagocytes enhance cerebral ischemic injury, activating the inflammatory apoptotic pathways. The aim of this review is to update evidence on phagocyte-related oxidative stress, focusing on the role of NOX2 as a potential therapeutic target to reduce ROS-related cerebral injury after stroke. Future Directions: Radical scavenger compounds (such as Ebselen and Edaravone) are under clinical investigation as a therapeutic approach against stroke. On the other hand, NOX inhibition might represent a promising strategy to prevent the stroke-related injury. Although selective NOX inhibitors are not yet available, nonselective compounds (such as apocynin and fasudil) provided encouraging results in preclinical studies. Whereas additional studies are needed to better evaluate this therapeutic potential in human beings, the development of specific NOX inhibitors (such as monoclonal antibodies, small-molecule inhibitors, or aptamers) might further improve brain recovery after stroke. Antioxid. Redox Signal. 23, 460–489. PMID:24635113

  13. The effects of mutation of the anr gene on the aerobic respiratory chain of Pseudomonas aeruginosa.

    PubMed

    Ray, A; Williams, H D

    1997-11-15

    The anr gene of Pseudomonas aeruginosa encodes a transcriptional regulator of anaerobic gene expression, homologous to the Fnr protein of Escherichia coli. We report here that Anr has a role in regulating the activity of the aerobic respiratory chain of P. aeruginosa. Strains with internal deletions in their anr gene had lowered levels of membrane bound cytochromes whilst the activity of the cytochrome c oxidase, cytochrome co (likely to be a cytochrome cbb3-type oxidase), and the cyanide-insensitive respiratory pathway was markedly higher than in the wild-type strains. These data, and the finding that provision of multiple copies of the anr gene led to severe repression of these respiratory activities, suggest that Anr is a repressor of aerobic respiratory pathways and possibly the terminal oxidases themselves. In contrast, Anr activated cytochrome c peroxidase, a respiratory chain linked enzyme induced under low oxygen conditions.

  14. [Respiratory distress].

    PubMed

    Galili, D; Garfunkel, A; Elad, S; Zusman, S P; Malamed, S F; Findler, M; Kaufman, E

    2002-01-01

    Dental treatment is usually conducted in the oral cavity and in very close proximity to the upper respiratory airway. The possibility of unintentionally compromising this airway is high in the dental environment. The accumulation of fluid (water or blood) near to the upper respiratory airway or the loosening of teeth fragmentations and fallen dental instruments can occur. Also, some of the drugs prescribed in the dental practice are central nervous system depressants and some are direct respiratory drive depressors. For this reason, awareness of the respiratory status of the dental patient is of paramount importance. This article focuses on several of the more common causes of respiratory distress, including airway obstruction, hyperventilation, asthma, bronchospasm, pulmonary edema, pulmonary embolism and cardiac insufficiency. The common denominator to all these conditions described here is that in most instances the patient is conscious. Therefore, on the one hand, valuable information can be retrieved from the patient making diagnosis easier than when the patient is unconscious. On the other hand, the conscious patient is under extreme apprehension and stress under such situations. Respiratory depression which occurs during conscious sedation or following narcotic analgesic medication will not be dealt with in this article. Advanced pain and anxiety control techniques such as conscious sedation and general anesthesia should be confined only to operators who undergo special extended training.

  15. Lysyl oxidase in colorectal cancer.

    PubMed

    Cox, Thomas R; Erler, Janine T

    2013-11-15

    Colorectal cancer is the third most prevalent form of cancer worldwide and fourth-leading cause of cancer-related mortality, leading to ~600,000 deaths annually, predominantly affecting the developed world. Lysyl oxidase is a secreted, extracellular matrix-modifying enzyme previously suggested to act as a tumor suppressor in colorectal cancer. However, emerging evidence has rapidly implicated lysyl oxidase in promoting metastasis of solid tumors and in particular colorectal cancer at multiple stages, affecting tumor cell proliferation, invasion, and angiogenesis. This emerging research has stimulated significant interest in lysyl oxidase as a strong candidate for developing and deploying inhibitors as functional efficacious cancer therapeutics. In this review, we discuss the rapidly expanding body of knowledge concerning lysyl oxidase in solid tumor progression, highlighting recent advancements in the field of colorectal cancer.

  16. Functional genomics identifies negative regulatory nodes controlling phagocyte oxidative burst

    PubMed Central

    Graham, Daniel B.; Becker, Christine E.; Doan, Aivi; Goel, Gautam; Villablanca, Eduardo J.; Knights, Dan; Mok, Amanda; Ng, Aylwin C.Y.; Doench, John G.; Root, David E.; Clish, Clary B.; Xavier, Ramnik J.

    2015-01-01

    The phagocyte oxidative burst, mediated by Nox2 NADPH oxidase-derived reactive oxygen species, confers host defense against a broad spectrum of bacterial and fungal pathogens. Loss-of-function mutations that impair function of the Nox2 complex result in a life-threatening immunodeficiency, and genetic variants of Nox2 subunits have been implicated in pathogenesis of inflammatory bowel disease (IBD). Thus, alterations in the oxidative burst can profoundly impact host defense, yet little is known about regulatory mechanisms that fine-tune this response. Here we report the discovery of regulatory nodes controlling oxidative burst by functional screening of genes within loci linked to human inflammatory disease. Implementing a multi-omics approach, we define transcriptional, metabolic and ubiquitin-cycling nodes controlled by Rbpj, Pfkl and Rnf145, respectively. Furthermore, we implicate Rnf145 in proteostasis of the Nox2 complex by endoplasmic reticulum-associated degradation. Consequently, ablation of Rnf145 in murine macrophages enhances bacterial clearance, and rescues the oxidative burst defects associated with Ncf4 haploinsufficiency. PMID:26194095

  17. The coordinate regulation of multiple terminal oxidases by the Pseudomonas putida ANR global regulator.

    PubMed

    Ugidos, Ana; Morales, Gracia; Rial, Eduardo; Williams, Huw D; Rojo, Fernando

    2008-07-01

    Pseudomonas putida KT2440 contains a branched aerobic respiratory chain with multiple terminal oxidases. Their relative proportion varies according to environmental conditions. The role of the oxygen-responsive ANR global regulator on expression of these terminal oxidases was analysed. During exponential growth in a highly aerated complete medium, ANR activated expression of the Cbb3-1 terminal oxidase (equivalent to Pseudomonas aeruginosa Cbb3-2), but had little role on expression of other terminal oxidases. In early stationary phase, or under oxygen limitation, inactivation of the anr gene led to increased expression of the bo(3)-type cytochrome (Cyo) and cyanide-insensitive (CIO) terminal oxidases, and to a much lower expression of Cbb3-1. DNase I footprints identified ANR binding sites at the promoters for these oxidases. Their location suggests that ANR is a transcriptional activator of Cbb3-1 genes and a repressor of CIO genes, consistent with expression data. ANR binding sites at the promoter for Cyo genes suggests a complex regulation in combination with other factors. Therefore, ANR coordinates expression of Cyo, CIO and Cbb3-1, but does not influence cytochrome aa3 and Cbb3-2 terminal oxidases under the conditions analysed. Functional assays showed that Cyo has a leading role during aerobic exponential growth, while Cbb3-1 becomes very important in stationary phase.

  18. Aspartate oxidase plays an important role in Arabidopsis stomatal immunity.

    PubMed

    Macho, Alberto P; Boutrot, Freddy; Rathjen, John P; Zipfel, Cyril

    2012-08-01

    Perception of pathogen-associated molecular patterns (PAMPs), such as bacterial flagellin (or the peptide flg22), by surface-localized receptors activates defense responses and subsequent immunity. In a previous forward-genetic screen aimed at the identification of Arabidopsis (Arabidopsis thaliana) flagellin-insensitive (fin) mutants, we isolated fin4, which is severely affected in flg22-triggered reactive oxygen species (ROS) bursts. Here, we report that FIN4 encodes the chloroplastic enzyme ASPARTATE OXIDASE (AO), which catalyzes the first irreversible step in the de novo biosynthesis of NAD. Genetic studies on the role of NAD have been hindered so far by the lethality of null mutants in NAD biosynthetic enzymes. Using newly identified knockdown fin alleles, we found that AO is required for the ROS burst mediated by the NADPH oxidase RBOHD triggered by the perception of several unrelated PAMPs. AO is also required for RBOHD-dependent stomatal closure. However, full AO activity is not required for flg22-induced responses that are RBOHD independent. Interestingly, although the fin4 mutation dramatically affects RBOHD function, it does not affect functions carried out by other members of the RBOH family, such as RBOHC and RBOHF. Finally, we determined that AO is required for stomatal immunity against the bacterium Pseudomonas syringae. Altogether, our work reveals a novel specific requirement for AO activity in PAMP-triggered RBOHD-dependent ROS burst and stomatal immunity. In addition, the availability of viable mutants for the chloroplastic enzyme AO will enable future detailed studies on the role of NAD metabolism in different cellular processes, including immunity, in Arabidopsis.

  19. Alternative oxidase of potato is an integral membrane protein synthesized de novo during aging of tuber slices. [Solanum tuberosum

    SciTech Connect

    Hiser, C.; McIntosh, L. )

    1990-05-01

    The rise in alternative respiratory capacity upon aging of potato (Solanum tuberosum) tuber slices is correlated with changes in mitochondrial membrane protein composition and a requirement for cytoplasmic protein synthesis. However, the lack of an antibody specific to the alternative oxidase has, until recently, prevented examination of the alternative oxidase protein(s) itself. We have employed a monoclonal antibody raised against the Sauromatum guttatum alternative oxidase to investigate developmental changes in the alternative pathway of aging potato slice mitochondria and to characterize the potato alternative oxidase by one- and two-dimensional gel electrophoresis. The relative levels of a 36 kilodalton protein parallel the rise in alternative path capacity. A plausible interpretation is that this alternative oxidase protein is synthesized de novo during aging of potato slices.

  20. Identification of prokaryotic homologues indicates an endosymbiotic origin for the alternative oxidases of mitochondria (AOX) and chloroplasts (PTOX).

    PubMed

    Atteia, Ariane; van Lis, Robert; van Hellemond, Jaap J; Tielens, Aloysius G M; Martin, William; Henze, Katrin

    2004-04-14

    The alternative oxidase is a ubiquinol oxidase that has been found to date in the mitochondrial respiratory chain of plants, some fungi and protists. Because of its sparse distribution among eukaryotic lineages and because of its diversity in regulatory mechanisms, the origin of AOX has been a mystery, particularly since no prokaryotic homologues have previously been identified. Here we report the identification of a gene encoding a clear homologue of the mitochondrial alternative oxidase in an alpha-proteobacterium, and the identification of three cyanobacterial genes that encode clear homologues of the plastid-specific alternative oxidase of plants and algae. These findings suggest that the eukaryotic nuclear genes for the alternative oxidases of mitochondria and chloroplasts were acquired via endosymbiotic gene transfer from the eubacterial ancestors of these two organelles, respectively.

  1. NADPH Oxidases in Vascular Pathology

    PubMed Central

    Konior, Anna; Schramm, Agata; Czesnikiewicz-Guzik, Marta

    2014-01-01

    Abstract Significance: Reactive oxygen species (ROS) play a critical role in vascular disease. While there are many possible sources of ROS, nicotinamide adenine dinucleotide phosphate (NADPH) oxidases play a central role. They are a source of “kindling radicals,” which affect other enzymes, such as nitric oxide synthase endothelial nitric oxide synthase or xanthine oxidase. This is important, as risk factors for atherosclerosis (hypertension, diabetes, hypercholesterolemia, and smoking) regulate the expression and activity of NADPH oxidases in the vessel wall. Recent Advances: There are seven isoforms in mammals: Nox1, Nox2, Nox3, Nox4, Nox5, Duox1 and Duox2. Nox1, Nox2, Nox4, and Nox5 are expressed in endothelium, vascular smooth muscle cells, fibroblasts, or perivascular adipocytes. Other homologues have not been found or are expressed at very low levels; their roles have not been established. Nox1/Nox2 promote the development of endothelial dysfunction, hypertension, and inflammation. Nox4 may have a role in protecting the vasculature during stress; however, when its activity is increased, it may be detrimental. Calcium-dependent Nox5 has been implicated in oxidative damage in human atherosclerosis. Critical Issues: NADPH oxidase-derived ROS play a role in vascular pathology as well as in the maintenance of normal physiological vascular function. We also discuss recently elucidated mechanisms such as the role of NADPH oxidases in vascular protection, vascular inflammation, pulmonary hypertension, tumor angiogenesis, and central nervous system regulation of vascular function and hypertension. Future Directions: Understanding the role of individual oxidases and interactions between homologues in vascular disease is critical for efficient pharmacological regulation of vascular NADPH oxidases in both the laboratory and clinical practice. Antioxid. Redox Signal. 20, 2794–2814. PMID:24180474

  2. Autophagy protein Rubicon mediates phagocytic NADPH oxidase activation in response to microbial infection or TLR stimulation.

    PubMed

    Yang, Chul-Su; Lee, Jong-Soo; Rodgers, Mary; Min, Chan-Ki; Lee, June-Yong; Kim, Hee Jin; Lee, Kwang-Hoon; Kim, Chul-Joong; Oh, Byungha; Zandi, Ebrahim; Yue, Zhenyu; Kramnik, Igor; Liang, Chengyu; Jung, Jae U

    2012-03-15

    Phagocytosis and autophagy are two important and related arms of the host's first-line defense against microbial invasion. Rubicon is a RUN domain containing cysteine-rich protein that functions as part of a Beclin-1-Vps34-containing autophagy complex. We report that Rubicon is also an essential, positive regulator of the NADPH oxidase complex. Upon microbial infection or Toll-like-receptor 2 (TLR2) activation, Rubicon interacts with the p22phox subunit of the NADPH oxidase complex, facilitating its phagosomal trafficking to induce a burst of reactive oxygen species (ROS) and inflammatory cytokines. Consequently, ectopic expression or depletion of Rubicon profoundly affected ROS, inflammatory cytokine production, and subsequent antimicrobial activity. Rubicon's actions in autophagy and in the NADPH oxidase complex are functionally and genetically separable, indicating that Rubicon functions in two ancient innate immune machineries, autophagy and phagocytosis, depending on the environmental stimulus. Rubicon may thus be pivotal to generating an optimal intracellular immune response against microbial infection.

  3. Gamma Ray Bursts

    NASA Technical Reports Server (NTRS)

    Gehrels, Neil; Meszaros, Peter

    2012-01-01

    Gamma-ray bursts (GRBs) are bright flashes of gamma-rays coming from the cosmos. They occur roughly once per day ,last typically lOs of seconds and are the most luminous events in the universe. More than three decades after their discovery, and after pioneering advances from space and ground experiments, they still remain mysterious. The launch of the Swift and Fermi satellites in 2004 and 2008 brought in a trove of qualitatively new data. In this review we survey the interplay between these recent observations and the theoretical models of the prompt GRB emission and the subsequent afterglows.

  4. UWB dual burst transmit driver

    SciTech Connect

    Dallum, Gregory E; Pratt, Garth C; Haugen, Peter C; Zumstein, James M; Vigars, Mark L; Romero, Carlos E

    2012-04-17

    A dual burst transmitter for ultra-wideband (UWB) communication systems generates a pair of precisely spaced RF bursts from a single trigger event. An input trigger pulse produces two oscillator trigger pulses, an initial pulse and a delayed pulse, in a dual trigger generator. The two oscillator trigger pulses drive a gated RF burst (power output) oscillator. A bias driver circuit gates the RF output oscillator on and off and sets the RF burst packet width. The bias driver also level shifts the drive signal to the level that is required for the RF output device.

  5. Isolation of ubiquinol oxidase from Paracoccus denitrificans and resolution into cytochrome bc1 and cytochrome c-aa3 complexes.

    PubMed

    Berry, E A; Trumpower, B L

    1985-02-25

    An enzyme complex with ubiquinol-cytochrome c oxidoreductase, cytochrome c oxidase, and ubiquinol oxidase activities was purified from a detergent extract of the plasma membrane of aerobically grown Paracoccus denitrificans. This ubiquinol oxidase consists of seven polypeptides and contains two b cytochromes, cytochrome c1, cytochrome aa3, and a previously unreported c-type cytochrome. This c-type cytochrome has an apparent Mr of 22,000 and an alpha absorption maximum at 552 nm. Retention of this c cytochrome through purification presumably accounts for the independence of ubiquinol oxidase activity on added cytochrome c. Ubiquinol oxidase can be separated into a 3-subunit bc1 complex, a 3-subunit c-aa3 complex, and a 57-kDa polypeptide. This, together with detection of covalently bound heme and published molecular weights of cytochrome c1 and the subunits of cytochrome c oxidase, allows tentative identification of most of the subunits of ubiquinol oxidase with the prosthetic groups present. Ubiquinol oxidase contains cytochromes corresponding to those of the mitochondrial bc1 complex, cytochrome c oxidase complex, and a bound cytochrome c. Ubiquinol-cytochrome c oxidoreductase activity of the complex is inhibited by inhibitors of the mitochondrial bc1 complex. Thus it seems likely that the pathway of electron transfer through the bc1 complex of ubiquinol oxidase is similar to that through the mitochondrial bc1 complex. The number of polypeptides present is less than half the number in the corresponding mitochondrial complexes. This structural simplicity may make ubiquinol oxidase from P. denitrificans a useful system with which to study the mechanisms of electron transfer and energy transduction in the bc1 and cytochrome c oxidase sections of the respiratory chain.

  6. [Alternative oxidase in industrial fungi].

    PubMed

    Gu, Shuai; Liu, Qiang; He, Hao; Li, Shuang

    2015-01-01

    Filamentous fungi have been used in industrial fermentation extensively. Based on non-phosphorylating electron transport process, alternative respiration pathway (ARP) acts as an energy overflow, which can balance carbon metabolism and electron transport, allow the continuance of tricarboxylic acid cycle without the formation of ATP, and permit the turnover of carbon skeletons. Alternative respiration pathway also plays an important role in the stress response of fungi and the physiological function of conditioned pathogen. Alternative oxidase (AOX) is the terminal oxidase responsible for the activity of alternative respiration pathway, which exists widely in higher plants, parts of fungi and algae. Owing to the property that alternative oxidase (AOX) is sensitive to salicylhydroxamic acid (SHAM) and insensitive to conventional inhibitors of cytochrome respiration, alternative respiration pathway by AOX is also named as cyanide-resistant respiration (CRR). In recent years, the study of the alternative respiration pathway and alternative oxidase has been a hot topic in the area involving cellular respiration metabolism. In this review we summarized the latest research advances about the functions of alternative respiration pathway and alternative oxidase in industrial fungi.

  7. A ROS-Assisted Calcium Wave Dependent on the AtRBOHD NADPH Oxidase and TPC1 Cation Channel Propagates the Systemic Response to Salt Stress1[OPEN

    PubMed Central

    Evans, Matthew J.; Choi, Won-Gyu

    2016-01-01

    Plants exhibit rapid, systemic signaling systems that allow them to coordinate physiological and developmental responses throughout the plant body, even to highly localized and quickly changing environmental stresses. The propagation of these signals is thought to include processes ranging from electrical and hydraulic networks to waves of reactive oxygen species (ROS) and cytoplasmic Ca2+ traveling throughout the plant. For the Ca2+ wave system, the involvement of the vacuolar ion channel TWO PORE CHANNEL1 (TPC1) has been reported. However, the precise role of this channel and the mechanism of cell-to-cell propagation of the wave have remained largely undefined. Here, we use the fire-diffuse-fire model to analyze the behavior of a Ca2+ wave originating from Ca2+ release involving the TPC1 channel in Arabidopsis (Arabidopsis thaliana). We conclude that a Ca2+ diffusion-dominated calcium-induced calcium-release mechanism is insufficient to explain the observed wave transmission speeds. The addition of a ROS-triggered element, however, is able to quantitatively reproduce the observed transmission characteristics. The treatment of roots with the ROS scavenger ascorbate and the NADPH oxidase inhibitor diphenyliodonium and analysis of Ca2+ wave propagation in the Arabidopsis respiratory burst oxidase homolog D (AtrbohD) knockout background all led to reductions in Ca2+ wave transmission speeds consistent with this model. Furthermore, imaging of extracellular ROS production revealed a systemic spread of ROS release that is dependent on both AtRBOHD and TPC1. These results suggest that, in the root, plant systemic signaling is supported by a ROS-assisted calcium-induced calcium-release mechanism intimately involving ROS production by AtRBOHD and Ca2+ release dependent on the vacuolar channel TPC1. PMID:27261066

  8. A ROS-Assisted Calcium Wave Dependent on the AtRBOHD NADPH Oxidase and TPC1 Cation Channel Propagates the Systemic Response to Salt Stress.

    PubMed

    Evans, Matthew J; Choi, Won-Gyu; Gilroy, Simon; Morris, Richard J

    2016-07-01

    Plants exhibit rapid, systemic signaling systems that allow them to coordinate physiological and developmental responses throughout the plant body, even to highly localized and quickly changing environmental stresses. The propagation of these signals is thought to include processes ranging from electrical and hydraulic networks to waves of reactive oxygen species (ROS) and cytoplasmic Ca(2+) traveling throughout the plant. For the Ca(2+) wave system, the involvement of the vacuolar ion channel TWO PORE CHANNEL1 (TPC1) has been reported. However, the precise role of this channel and the mechanism of cell-to-cell propagation of the wave have remained largely undefined. Here, we use the fire-diffuse-fire model to analyze the behavior of a Ca(2+) wave originating from Ca(2+) release involving the TPC1 channel in Arabidopsis (Arabidopsis thaliana). We conclude that a Ca(2+) diffusion-dominated calcium-induced calcium-release mechanism is insufficient to explain the observed wave transmission speeds. The addition of a ROS-triggered element, however, is able to quantitatively reproduce the observed transmission characteristics. The treatment of roots with the ROS scavenger ascorbate and the NADPH oxidase inhibitor diphenyliodonium and analysis of Ca(2+) wave propagation in the Arabidopsis respiratory burst oxidase homolog D (AtrbohD) knockout background all led to reductions in Ca(2+) wave transmission speeds consistent with this model. Furthermore, imaging of extracellular ROS production revealed a systemic spread of ROS release that is dependent on both AtRBOHD and TPC1 These results suggest that, in the root, plant systemic signaling is supported by a ROS-assisted calcium-induced calcium-release mechanism intimately involving ROS production by AtRBOHD and Ca(2+) release dependent on the vacuolar channel TPC1.

  9. L-carnosine modulates respiratory burst and reactive oxygen species production in neutrophil biochemistry and function: may oral dosage form of non-hydrolized dipeptide L-carnosine complement anti-infective anti-influenza flu treatment, prevention and self-care as an alternative to the conventional vaccination?

    PubMed

    Babizhayev, Mark A; Deyev, Anatoliy I; Yegorov, Yegor E

    2014-05-01

    Influenza A is a viral disease of global dimension, presenting with high morbidity and mortality in annual epidemics, and in pandemics which are of infrequent occurrence but which have very high attack rates. Influenza vaccines of the future must be directed toward use of conserved group-specific viral antigens, such as are present in transitional proteins which are exposed during the fusion of virus to the host cell. Influenza probes revealed a continuing battle for survival between host and parasite in which the host population updates the specificity of its pool of humoral immunity by contact with and response to infection with the most recent viruses which possess altered antigenic specificity in their hemagglutinin (HA) ligand. It is well known that the HA protein is found on the surface of the influenza virus particle and is responsible for binding to receptors on host cells and initiating infection. Polymorphonuclear neutrophils (PMN) have been reported to be involved in the initial host response to influenza A virus (IAV). Early after IAV infection, neutrophils infiltrate the airway probably due to release of chemokines that attract PMN. Clearly, severe IAV infection is characterized by increased neutrophil influx into the lung or upper respiratory tract. Carnosine (β-alanyl-L-histidine) and anserine (N-β-alanyl-1-methyl-L-histidine) are found in skeletal muscle of most vertebrates, including those used for food; for example, 100 g of chicken breast contains 400 mg (17.6 mmol/L) of carnosine and 1020 mg (33.6 mmol/l) of anserine. Carnosine-stimulated respiratory burst in neutrophils is a universal biological mechanism of influenza virus destruction. Our own studies revealed previously unappreciated functional effects of carnosine and related histidine containing compounds as a natural biological prevention and barrier against Influenza virus infection, expand public understanding of the antiviral properties of imidazole-containing dipeptide based

  10. Respiratory Home Health Care

    MedlinePlus

    ... Healthy Living > Living With Lung Disease > Respiratory Home Health Care Font: Aerosol Delivery Oxygen Resources Immunizations Pollution Nutrition ... Disease Articles written by Respiratory Experts Respiratory Home Health Care Respiratory care at home can contribute to improved ...

  11. Pathophysiological Approaches of Acute Respiratory Distress syndrome: Novel Bases for Study of Lung Injury

    PubMed Central

    Castillo, R.L; Carrasco Loza, R; Romero-Dapueto, C

    2015-01-01

    Experimental approaches have been implemented to research the lung damage related-mechanism. These models show in animals pathophysiological events for acute respiratory distress syndrome (ARDS), such as neutrophil activation, reactive oxygen species burst, pulmonary vascular hypertension, exudative edema, and other events associated with organ dysfunction. Moreover, these approaches have not reproduced the clinical features of lung damage. Lung inflammation is a relevant event in the develop of ARDS as component of the host immune response to various stimuli, such as cytokines, antigens and endotoxins. In patients surviving at the local inflammatory states, transition from injury to resolution is an active mechanism regulated by the immuno-inflammatory signaling pathways. Indeed, inflammatory process is regulated by the dynamics of cell populations that migrate to the lung, such as neutrophils and on the other hand, the role of the modulation of transcription factors and reactive oxygen species (ROS) sources, such as nuclear factor kappaB and NADPH oxidase. These experimental animal models reproduce key components of the injury and resolution phases of human ALI/ARDS and provide a methodology to explore mechanisms and potential new therapies. PMID:26312099

  12. Swift's 500th Gamma Ray Burst

    NASA Video Gallery

    On April 13, 2010, NASA's Swift Gamma-ray Burst Explorer satellite discovered its 500th burst. Swift's main job is to quickly localize each gamma-ray burst (GRB), report its position so that others...

  13. Bursts de raios gama

    NASA Astrophysics Data System (ADS)

    Braga, J.

    2003-02-01

    Nos últimos anos, graças principalmente aos dados obtidos pelo Compton Gamma-Ray Observatory e pelo satélite ítalo-holandês BeppoSAX, grandes avanços foram obtidos no nosso conhecimento sobre os fascinantes e enigmáticos fenômenos conhecidos por "bursts"de raios gama. Neste trabalho é feita uma revisão sobre a fenomenologia desses misteriosos objetos e são apresentados os desenvolvimentos recentes nessa área palpitante da astrofísica moderna, ressaltando tanto os resultados observacionais obtidos até o momento quanto os modelos teóricos propostos para explixá-los.

  14. Quantum key based burst confidentiality in optical burst switched networks.

    PubMed

    Balamurugan, A M; Sivasubramanian, A

    2014-01-01

    The optical burst switching (OBS) is an emergent result to the technology concern that could achieve a feasible network in future. They are endowed with the ability to meet the bandwidth requirement of those applications that require intensive bandwidth. There are more domains opening up in the OBS that evidently shows their advantages and their capability to face the future network traffic. However, the concept of OBS is still far from perfection facing issues in case of security threat. The transfer of optical switching paradigm to optical burst switching faces serious downfall in the fields of burst aggregation, routing, authentication, dispute resolution, and quality of service (QoS). This paper deals with employing RC4 (stream cipher) to encrypt and decrypt bursts thereby ensuring the confidentiality of the burst. Although the use of AES algorithm has already been proposed for the same issue, by contrasting the two algorithms under the parameters of burst encryption and decryption time, end-to-end delay, it was found that RC4 provided better results. This paper looks to provide a better solution for the confidentiality of the burst in OBS networks.

  15. Quantum Key Based Burst Confidentiality in Optical Burst Switched Networks

    PubMed Central

    Balamurugan, A. M.; Sivasubramanian, A.

    2014-01-01

    The optical burst switching (OBS) is an emergent result to the technology concern that could achieve a feasible network in future. They are endowed with the ability to meet the bandwidth requirement of those applications that require intensive bandwidth. There are more domains opening up in the OBS that evidently shows their advantages and their capability to face the future network traffic. However, the concept of OBS is still far from perfection facing issues in case of security threat. The transfer of optical switching paradigm to optical burst switching faces serious downfall in the fields of burst aggregation, routing, authentication, dispute resolution, and quality of service (QoS). This paper deals with employing RC4 (stream cipher) to encrypt and decrypt bursts thereby ensuring the confidentiality of the burst. Although the use of AES algorithm has already been proposed for the same issue, by contrasting the two algorithms under the parameters of burst encryption and decryption time, end-to-end delay, it was found that RC4 provided better results. This paper looks to provide a better solution for the confidentiality of the burst in OBS networks. PMID:24578663

  16. Respiratory Distress

    NASA Technical Reports Server (NTRS)

    1976-01-01

    The University of Miami School of Medicine asked the Research Triangle Institute for assistance in improvising the negative pressure technique to relieve respiratory distress in infants. Marshall Space Flight Center and Johnson Space Center engineers adapted this idea to the lower-body negative-pressure system seals used during the Skylab missions. Some 20,000 babies succumb to respiratory distress in the U.S. each year, a condition in which lungs progressively lose their ability to oxygenate blood. Both positive and negative pressure techniques have been used - the first to force air into lungs, the second to keep infant's lungs expanded. Negative pressure around chest helps the baby expand his lungs and maintain proper volume of air. If doctors can keep the infant alive for four days, the missing substance in the lungs will usually form in sufficient quantity to permit normal breathing. The Skylab chamber and its leakproof seals were adapted for medical use.

  17. CtaM Is Required for Menaquinol Oxidase aa3 Function in Staphylococcus aureus

    PubMed Central

    Schurig-Briccio, Lici A.; Gerdes, Svetlana Y.; Gennis, Robert B.

    2016-01-01

    ABSTRACT Staphylococcus aureus is the leading cause of skin and soft tissue infections, bacteremia, osteomyelitis, and endocarditis in the developed world. The ability of S. aureus to cause substantial disease in distinct host environments is supported by a flexible metabolism that allows this pathogen to overcome challenges unique to each host organ. One feature of staphylococcal metabolic flexibility is a branched aerobic respiratory chain composed of multiple terminal oxidases. Whereas previous biochemical and spectroscopic studies reported the presence of three different respiratory oxygen reductases (o type, bd type, and aa3 type), the genome contains genes encoding only two respiratory oxygen reductases, cydAB and qoxABCD. Previous investigation showed that cydAB and qoxABCD are required to colonize specific host organs, the murine heart and liver, respectively. This work seeks to clarify the relationship between the genetic studies showing the unique roles of the cydAB and qoxABCD in virulence and the respiratory reductases reported in the literature. We establish that QoxABCD is an aa3-type menaquinol oxidase but that this enzyme is promiscuous in that it can assemble as a bo3-type menaquinol oxidase. However, the bo3 form of QoxABCD restricts the carbon sources that can support the growth of S. aureus. In addition, QoxABCD function is supported by a previously uncharacterized protein, which we have named CtaM, that is conserved in aerobically respiring Firmicutes. In total, these studies establish the heme A biosynthesis pathway in S. aureus, determine that QoxABCD is a type aa3 menaquinol oxidase, and reveal CtaM as a new protein required for type aa3 menaquinol oxidase function in multiple bacterial genera. PMID:27406563

  18. Burst Detector Sensitivity: Past, Present and Future

    NASA Technical Reports Server (NTRS)

    Band, David L.

    2005-01-01

    I compare the burst detection sensitivity of CGRO's BATSE, Swift's BAT, the GLAST Burst Monitor (GBM) and EXIST as a function of a burst s spectrum and duration. A detector's overall burst sensitivity depends on its energy sensitivity and set of accumulations times (Delta)t; these two factors shape the detected burst population. For example, relative to BATSE, the BAT s softer energy band decreases the detection rate of short, hard bursts, while the BAT s longer accumulation times increase the detection rate of long, soft bursts. Consequently, Swift is detecting long, low fluence bursts (2-3 x fainter than BATSE).

  19. Respiratory chain proteins.

    PubMed

    Kadenbach, B; Schneyder, B; Mell, O; Stroh, S; Reimann, A

    1991-01-01

    Mammalian mitochondrial DNA codes for 13 proteins, which are all components of energy transducing enzyme complexes of the respiratory chain, i.e. the complexes which translocate protons across the inner mitochondrial membrane. The number of subunits of these enzyme complexes increase with increasing evolutionary stage of the organism. The additional nuclear coded subunits of the enzyme complexes from higher organisms are involved in the regulation of respiration, as demonstrated by the influence of intraliposomal ATP and ADP on the reconstituted cytochrome c oxidase (COX) from bovine heart. This regulation is not found with the reconstituted enzyme from P. denitrificans, which lacks the nuclear coded subunits. Some of the nuclear coded subunits occur in tissue-specific isoforms, as reported for COX and NADH dehydrogenase. Tissue-specific regulation of COX activity is also demonstrated by the differential effects of intraliposomal ADP on the kinetics of reconstituted COX from bovine liver and heart, which differ in subunits VIa, VIIa and VIII. At least 3 different COX isozymes occur in bovine liver, heart or skeletal muscle and smooth muscle. An evolutionary relationship between COX subunits VIa and VIc and between VIIa and VIIb is suggested based on the crossreactivity of monoclonal antibodies, amino acid sequence homology and hybridization at low stringency of PCR-amplified cDNAs for subunits VIa-1, VIa-h and VIc from the rat.

  20. The Respiratory Chain of Alkaliphilic Bacteria

    SciTech Connect

    Terry Ann Krulwich

    2008-01-29

    Alkaliphilic bacteria that grow at extremely high pH are confronted by particular bioenergetic problems in carrying out oxidative phosphorylation. This project focused on the properties and adaptations of the respiratory chain. The respiratory chain as a whole, the redox poises of its components and several individual complexes of the respiratory chain of alkaliphilic Bacillus pseudofirmus OF4 have been characterized as part of this project and, importantly, this project has helped support the development of genetic tools that make B. pseudofirmus OF4 the most genetically tractable and, hence, most bioenergetically characterized extreme alkaliphile. Evidence has been obtained for a pivotal role of the cca3-type terminal oxidase in oxidative phosphorylation, especially at high pH and motifs that may be relevant to that special role have been identified.

  1. Gamma-ray burst populations

    NASA Astrophysics Data System (ADS)

    Virgili, Francisco Javier

    Over the last fifty years the field of gamma-ray bursts has shown incredible growth, but the amassing of data has also left observers and theorists alike wondering about some of the basic questions surrounding these phenomena. Additionally, these events show remarkable individuality and extrema, ranging in redshift throughout the observable universe and over ten orders of magnitude in energy. This work focuses on analyzing groups of bursts that are different from the general trend and trying to understand whether these bursts are from different intrinsic populations and if so, what can be said about their progenitors. This is achieved through numerical Monte Carlo simulations and statistical inference in conjunction with current GRB observations. Chapter 1 gives a general introduction of gamma-ray burst theory and observations in a semi-historical context. Chapter 2 provides an introduction to the theory and practical issues surrounding the numerical simulations and statistics. Chapters 3--5 are each dedicated to a specific problem relating to a different type of GRB population: high-luminosity v. low-luminosity bursts, constraints from high-redshift bursts, and Type I v. Type II bursts. Chapter 6 follows with concluding remarks.

  2. Concept for LEU Burst Reactor

    SciTech Connect

    Klein, Steven Karl; Kimpland, Robert Herbert

    2016-03-07

    Design and performance of a proposed LEU burst reactor are sketched. Salient conclusions reached are the following: size would be ~1,500 kg or greater, depending on the size of the central cavity; internal stresses during burst require split rings for relief; the reactor would likely require multiple control and safety rods for fine control; the energy spectrum would be comparable to that of HEU machines; and burst yields and steady-state power levels will be significantly greater in an LEU reactor.

  3. The Burst of the Century

    NASA Astrophysics Data System (ADS)

    Fruchter, Andrew

    2014-09-01

    The extraordinarily bright GRB 130427A has provided a multiwavelength data set unprecedented in the history of the field. However the light curve of this burst, like that of the large majority of LAT bursts, shows a puzzling lack of a jet break (the hallmark of a collimated outflow). We propose to continue our long-term monitoring of this GRB through to the end of 2015. A detection of a jet break will give us a direct measure of the absolute energy of the burst; its absence will effectively rule out a rotating neutron star as the central engine of the GRB.

  4. Respiratory processes in non-photosynthetic plastids

    PubMed Central

    Renato, Marta; Boronat, Albert; Azcón-Bieto, Joaquín

    2015-01-01

    Chlororespiration is a respiratory process located in chloroplast thylakoids which consists in an electron transport chain from NAD(P)H to oxygen. This respiratory chain involves the NAD(P)H dehydrogenase complex, the plastoquinone pool and the plastid terminal oxidase (PTOX), and it probably acts as a safety valve to prevent the over-reduction of the photosynthetic machinery in stress conditions. The existence of a similar respiratory activity in non-photosynthetic plastids has been less studied. Recently, it has been reported that tomato fruit chromoplasts present an oxygen consumption activity linked to ATP synthesis. Etioplasts and amyloplasts contain several electron carriers and some subunits of the ATP synthase, so they could harbor a similar respiratory process. This review provides an update on the study about respiratory processes in chromoplasts, identifying the major gaps that need to be addressed in future research. It also reviews the proteomic data of etioplasts and amyloplasts, which suggest the presence of a respiratory electron transport chain in these plastids. PMID:26236317

  5. 30 CFR 57.3461 - Rock bursts.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Rock bursts. 57.3461 Section 57.3461 Mineral...-Underground Only § 57.3461 Rock bursts. (a) Operators of mines which have experienced a rock burst shall— (1) Within twenty four hours report to the nearest MSHA office each rock burst which: (i) Causes persons...

  6. 30 CFR 57.3461 - Rock bursts.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Rock bursts. 57.3461 Section 57.3461 Mineral...-Underground Only § 57.3461 Rock bursts. (a) Operators of mines which have experienced a rock burst shall— (1) Within twenty four hours report to the nearest MSHA office each rock burst which: (i) Causes persons...

  7. 30 CFR 57.3461 - Rock bursts.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Rock bursts. 57.3461 Section 57.3461 Mineral...-Underground Only § 57.3461 Rock bursts. (a) Operators of mines which have experienced a rock burst shall— (1) Within twenty four hours report to the nearest MSHA office each rock burst which: (i) Causes persons...

  8. 30 CFR 57.3461 - Rock bursts.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Rock bursts. 57.3461 Section 57.3461 Mineral...-Underground Only § 57.3461 Rock bursts. (a) Operators of mines which have experienced a rock burst shall— (1) Within twenty four hours report to the nearest MSHA office each rock burst which: (i) Causes persons...

  9. 30 CFR 57.3461 - Rock bursts.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Rock bursts. 57.3461 Section 57.3461 Mineral...-Underground Only § 57.3461 Rock bursts. (a) Operators of mines which have experienced a rock burst shall— (1) Within twenty four hours report to the nearest MSHA office each rock burst which: (i) Causes persons...

  10. Burst interference in TDMA radio systems

    NASA Astrophysics Data System (ADS)

    Lei, Z.; Chen, M.-X.; Feher, K.

    1985-12-01

    Burst interference is inherent in TDMA subscriber radio and satellite communications systems. Spectral and interference properties of burst modulated signals are investigated. Owing to the burst mode operation of the TDMA system its spectrum spreads; this spread increases with the increase of burst gating rate and the decrease of the burst length. A theoretical derivation of the Pe = f(Eb/N0; I) performance, computer simulation and experimental results of IJF-OQPSK and conventional QPSK burst operated systems are presented. The performance of these systems in the presence of burst mode TDMA co-channel and adjacent channel interference (I) is evaluated.

  11. Cytochrome cbb3 of Thioalkalivibrio is a Na+-pumping cytochrome oxidase

    PubMed Central

    Muntyan, Maria S.; Cherepanov, Dmitry A.; Malinen, Anssi M.; Bloch, Dmitry A.; Sorokin, Dimitry Y.; Severina, Inna I.; Ivashina, Tatiana V.; Lahti, Reijo; Muyzer, Gerard; Skulachev, Vladimir P.

    2015-01-01

    Cytochrome c oxidases (Coxs) are the basic energy transducers in the respiratory chain of the majority of aerobic organisms. Coxs studied to date are redox-driven proton-pumping enzymes belonging to one of three subfamilies: A-, B-, and C-type oxidases. The C-type oxidases (cbb3 cytochromes), which are widespread among pathogenic bacteria, are the least understood. In particular, the proton-pumping machinery of these Coxs has not yet been elucidated despite the availability of X-ray structure information. Here, we report the discovery of the first (to our knowledge) sodium-pumping Cox (Scox), a cbb3 cytochrome from the extremely alkaliphilic bacterium Thioalkalivibrio versutus. This finding offers clues to the previously unknown structure of the ion-pumping channel in the C-type Coxs and provides insight into the functional properties of this enzyme. PMID:26056262

  12. X-ray bursts: Observation versus theory

    NASA Technical Reports Server (NTRS)

    Lewin, W. H. G.

    1981-01-01

    Results of various observations of common type I X-ray bursts are discussed with respect to the theory of thermonuclear flashes in the surface layers of accreting neutron stars. Topics covered include burst profiles; irregular burst intervals; rise and decay times and the role of hydrogen; the accuracy of source distances; accuracy in radii determination; radius increase early in the burst; the super Eddington limit; temperatures at burst maximum; and the role of the magnetic field.

  13. Lysyl oxidase in cancer research.

    PubMed

    Perryman, Lara; Erler, Janine T

    2014-01-01

    Metastasis is the main reason for cancer-associated deaths and therapies are desperately needed to target the progression of cancer. Lysyl oxidase (LOX) plays a pivotal role in cancer progression, including metastasis, and is therefore is an attractive therapeutic target. In this review we will breakdown the process of cancer progression and the various roles that LOX plays has in the advancement of cancer. We will highlight why LOX is an exciting therapeutic target for the future.

  14. Decameter Type III-Like Bursts

    NASA Astrophysics Data System (ADS)

    Melnik, V. N.; Konovalenko, A. A.; Rutkevych, B. P.; Rucker, H. O.; Dorovskyy, V. V.; Abranin, E. P.; Lecacheux, A.; Brazhenko, A. I.; Stanislavskyy, A. A.

    2007-12-01

    Starting from 1960s Type III-like bursts (Type III bursts with high drift rates) in a wide frequency range from 300 to 950MHz have been observed. These new bursts observed at certain frequency being compared to the usual Type III bursts at the same frequency show similar behaviour but feature frequency drift 2-6 times higher than the normal bursts. In this paper we report the first observations of Type III-like bursts in decameter range, carried out during summer campaigns 2002 - 2004 at UTR-2 radio telescope. The circular polarization of the bursts was measured by the radio telescope URAN-2 in 2004. The observed bursts are analyzed and compared with usual Type III bursts in the decameter range. From the analysis of over 1100 Type III-like bursts, their main parameters have been found. Characteristic feature of the observed bursts is similar to Type III-like bursts at other frequencies, i.e. measured drift rates (5-10 MHz/s) of this bursts are few times larger than that for usual Type III bursts, and their durations (1-2 s) are few times smaller than that for usual Type III bursts in this frequency band.

  15. [Respiratory allergies].

    PubMed

    Chiriac, Anca Mirela; Demoly, Pascal

    2013-04-01

    Respiratory allergies represent a global and public health problem, due to their prevalence (still increasing), morbidity, impact on the quality of life and costs for the society. They mainly concern rhinitis (or rhinoconjunctivitis) and asthma. The diagnosis of allergy is dependent on a history of symptoms on exposure to an allergen together with the detection of allergen-specific IgE. Accurate diagnosis of allergies opens up therapeutic options that are otherwise not appropriate, such as allergen immunotherapy and allergen avoidance, that are prescribed following a stepwise approach. It has been a century since the first trial in specific immunotherapy was performed and this still remains the only disease modifying treatment for allergic individuals. In terms of route of administration, sublingual immunotherapy represents a good alternative to subcutaneous immunotherapy, considering its proven efficacy and better safety profile.

  16. Unique targeting of cytosolic phospholipase A2 to plasma membranes mediated by the NADPH oxidase in phagocytes

    PubMed Central

    Shmelzer, Zeev; Haddad, Nurit; Admon, Ester; Pessach, Itai; Leto, Thomas L.; Eitan-Hazan, Zahit; Hershfinkel, Michal; Levy, Rachel

    2003-01-01

    Cytosolic phospholipase A2 (cPLA2)–generated arachidonic acid (AA) has been shown to be an essential requirement for the activation of NADPH oxidase, in addition to its being the major enzyme involved in the formation of eicosanoid at the nuclear membranes. The mechanism by which cPLA2 regulates NADPH oxidase activity is not known, particularly since the NADPH oxidase complex is localized in the plasma membranes of stimulated cells. The present study is the first to demonstrate that upon stimulation cPLA2 is transiently recruited to the plasma membranes by a functional NADPH oxidase in neutrophils and in granulocyte-like PLB-985 cells. Coimmunoprecipitation experiments and double labeling immunofluorescence analysis demonstrated the unique colocalization of cPLA2 and the NADPH oxidase in plasma membranes of stimulated cells, in correlation with the kinetic burst of superoxide production. A specific affinity in vitro binding was detected between GST-p47phox or GST-p67phox and cPLA2 in lysates of stimulated cells. The association between these two enzymes provides the molecular basis for AA released by cPLA2 to activate the assembled NADPH oxidase. The ability of cPLA2 to regulate two different functions in the same cells (superoxide generation and eicosanoid production) is achieved by a novel dual subcellular localization of cPLA2 to different targets. PMID:12913107

  17. The interaction of intrinsic dynamics and network topology in determining network burst synchrony.

    PubMed

    Gaiteri, Chris; Rubin, Jonathan E

    2011-01-01

    The pre-Bötzinger complex (pre-BötC), within the mammalian respiratory brainstem, represents an ideal system for investigating the synchronization properties of complex neuronal circuits via the interaction of cell-type heterogeneity and network connectivity. In isolation, individual respiratory neurons from the pre-BötC may be tonically active, rhythmically bursting, or quiescent. Despite this intrinsic heterogeneity, coupled networks of pre-BötC neurons en bloc engage in synchronized bursting that can drive inspiratory motor neuron activation. The region's connection topology has been recently characterized and features dense clusters of cells with occasional connections between clusters. We investigate how the dynamics of individual neurons (quiescent/bursting/tonic) and the betweenness centrality of neurons' positions within the network connectivity graph interact to govern network burst synchrony, by simulating heterogeneous networks of computational model pre-BötC neurons. Furthermore, we compare the prevalence and synchrony of bursting across networks constructed with a variety of connection topologies, analyzing the same collection of heterogeneous neurons in small-world, scale-free, random, and regularly structured networks. We find that several measures of network burst synchronization are determined by interactions of network topology with the intrinsic dynamics of neurons at central network positions and by the strengths of synaptic connections between neurons. Surprisingly, despite the functional role of synchronized bursting within the pre-BötC, we find that synchronized network bursting is generally weakest when we use its specific connection topology, which leads to synchrony within clusters but poor coordination across clusters. Overall, our results highlight the relevance of interactions between topology and intrinsic dynamics in shaping the activity of networks and the concerted effects of connectivity patterns and dynamic heterogeneities.

  18. Lungs and Respiratory System

    MedlinePlus

    ... Your 1- to 2-Year-Old Lungs and Respiratory System KidsHealth > For Parents > Lungs and Respiratory System Print ... ll have taken at least 600 million breaths. Respiratory System Basics All of this breathing couldn't happen ...

  19. Lungs and Respiratory System

    MedlinePlus

    ... Your 1- to 2-Year-Old Lungs and Respiratory System KidsHealth > For Parents > Lungs and Respiratory System A ... ll have taken at least 600 million breaths. Respiratory System Basics All of this breathing couldn't happen ...

  20. Enhanced expression of Rhizobium etli cbb₃ oxidase improves drought tolerance of common bean symbiotic nitrogen fixation.

    PubMed

    Talbi, C; Sánchez, C; Hidalgo-Garcia, A; González, E M; Arrese-Igor, C; Girard, L; Bedmar, E J; Delgado, M J

    2012-09-01

    To investigate the involvement of Rhizobium etli cbb(3) oxidase in the response of Phaseolus vulgaris to drought, common bean plants were inoculated with the R. etli strain, CFNX713, overexpressing this oxidase in bacteroids (cbb(3)(+)) and subjected to drought conditions. The negative effect of drought on plant and nodule dryweight, nitrogen content, and nodule functionality was more pronounced in plants inoculated with the wild-type (WT) strain than in those inoculated with the cbb(3)(+) strain. Regardless of the plant treatment, bacteroids produced by the cbb(3)(+) strain showed higher respiratory capacity than those produced by the WT strain. Inoculation of plants with the cbb(3)(+) strain alleviated the negative effect of a moderate drought on the respiratory capacity of bacteroids and the energy charge of the nodules. Expression of the FixP and FixO components of the cbb(3) oxidase was higher in bacteroids of the cbb(3)(+) strain than in those of the WT strain under all experimental conditions. The decline in sucrose synthase activity and the decrease in dicarboxylic acids provoked by moderate drought stress were more pronounced in nodules from plants inoculated with the WT strain than in those inoculated with the cbb(3)(+) strain. Taken together, these results suggest that inoculation of plants with a R. etli strain having enhanced expression of cbb(3) oxidase in bacteroids reduces the sensitivity of P. vulgaris-R. etli symbiosis to drought and can modulate carbon metabolism in nodules.

  1. Heterogeneity in Short Gamma-Ray Bursts

    NASA Technical Reports Server (NTRS)

    Norris, Jay P.; Gehrels Neil; Scargle, Jeffrey D.

    2011-01-01

    We analyze the Swift/BAT sample of short gamma-ray bursts, using an objective Bayesian Block procedure to extract temporal descriptors of the bursts' initial pulse complexes (IPCs). The sample comprises 12 and 41 bursts with and without extended emission (EE) components, respectively. IPCs of non-EE bursts are dominated by single pulse structures, while EE bursts tend to have two or more pulse structures. The medians of characteristic timescales - durations, pulse structure widths, and peak intervals - for EE bursts are factors of approx 2-3 longer than for non-EE bursts. A trend previously reported by Hakkila and colleagues unifying long and short bursts - the anti-correlation of pulse intensity and width - continues in the two short burst groups, with non-EE bursts extending to more intense, narrower pulses. In addition we find that preceding and succeeding pulse intensities are anti-correlated with pulse interval. We also examine the short burst X-ray afterglows as observed by the Swift/XRT. The median flux of the initial XRT detections for EE bursts (approx 6 X 10(exp -10) erg / sq cm/ s) is approx > 20 x brighter than for non-EE bursts, and the median X-ray afterglow duration for EE bursts (approx 60,000 s) is approx 30 x longer than for non-EE bursts. The tendency for EE bursts toward longer prompt-emission timescales and higher initial X-ray afterglow fluxes implies larger energy injections powering the afterglows. The longer-lasting X-ray afterglows of EE bursts may suggest that a significant fraction explode into more dense environments than non-EE bursts, or that the sometimes-dominant EE component efficiently p()wers the afterglow. Combined, these results favor different progenitors for EE and non-EE short bursts.

  2. HETEROGENEITY IN SHORT GAMMA-RAY BURSTS

    SciTech Connect

    Norris, Jay P.; Gehrels, Neil

    2011-07-01

    We analyze the Swift/BAT sample of short gamma-ray bursts, using an objective Bayesian Block procedure to extract temporal descriptors of the bursts' initial pulse complexes (IPCs). The sample is comprised of 12 and 41 bursts with and without extended emission (EE) components, respectively. IPCs of non-EE bursts are dominated by single pulse structures, while EE bursts tend to have two or more pulse structures. The medians of characteristic timescales-durations, pulse structure widths, and peak intervals-for EE bursts are factors of {approx}2-3 longer than for non-EE bursts. A trend previously reported by Hakkila and colleagues unifying long and short bursts-the anti-correlation of pulse intensity and width-continues in the two short burst groups, with non-EE bursts extending to more intense, narrower pulses. In addition, we find that preceding and succeeding pulse intensities are anti-correlated with pulse interval. We also examine the short burst X-ray afterglows as observed by the Swift/X-Ray Telescope (XRT). The median flux of the initial XRT detections for EE bursts ({approx}6x10{sup -10} erg cm{sup -2} s{sup -1}) is {approx}>20x brighter than for non-EE bursts, and the median X-ray afterglow duration for EE bursts ({approx}60,000 s) is {approx}30x longer than for non-EE bursts. The tendency for EE bursts toward longer prompt-emission timescales and higher initial X-ray afterglow fluxes implies larger energy injections powering the afterglows. The longer-lasting X-ray afterglows of EE bursts may suggest that a significant fraction explode into denser environments than non-EE bursts, or that the sometimes-dominant EE component efficiently powers the afterglow. Combined, these results favor different progenitors for EE and non-EE short bursts.

  3. Physiology and pathophysiology of respiratory arrest by cyanide poisoning

    SciTech Connect

    Klimmek, R.

    1993-05-13

    Respiratory arrest, preceded by hyperventilation, is the primary cause of death in acute cyanide poisoning. Hyperventilation followed by apnea is also observed without intoxication. Hyperventilation and apnea in untoxicated subjects and animals are analyzed for the underlying physiological and biochemical changes and compared with those found during cyanide poisoning. The study reveals that the respiratory autoregulation appears to be the same under both conditions. Respiratory arrest is controlled by cerebral PCO2 and can occur without hypoxia or inhibition of cytochrome oxidase. It is postulated that respiratory arrest is a 'desperate act' thrust on the respiratory neurons by a critical exhaustion of their energy store (ATP) due to the rapid firing in the period of hyperventilation. The point of no return may be reached when anoxia and/or partial inhibition of cytochrome oxidase prevent the neurons from replenishing the ATP store. The formation of Fe3+ cyanide complexes. exemplified by the metHb producer DMAP, appears to give the best results with regard to the restoration of spontaneous respiration. The study of respiratory autoregulation may also be helpful in developing and understanding other therapeutic approaches.

  4. The Respiratory Chain of Plant Mitochondria

    PubMed Central

    Storey, Bayard T.

    1971-01-01

    Energy-linked reverse electron transport from succinate to endogenous NAD in tightly coupled mung bean (Phaseolus aureus) mitochondria may be driven by ATP if the two terminal oxidases of these mitochondria are inhibited, or may be driven by the free energy of succinate oxidation. This reaction is specific to the first site of energy conservation of the respiratory chain; it does not occur in the presence of uncoupler. If mung bean mitochondria become anaerobic during oxidation of succinate, their endogenous NAD becomes reduced in the presence of uncoupler, provided that both inorganic phosphate (Pi) and ATP are present. No reduction occurs in the absence of Pi, even in the presence of ATP added to provide a high phosphate potential. If fluorooxaloacetate is present in the uncoupled, aerobic steady state, no reduction of endogenous NAD occurs on anaerobiosis; this compound is an inhibitor of malate dehydrogenase. This result implies that endogenous NAD is reduced by malate formed from the fumarate generated during succinate oxidation. The source of free energy is most probably the endogenous energy stores in the form of acetyl CoA, or intermediates convertible to acetyl CoA, which removes the oxaloacetate formed from malate, thus driving the reaction towards reduction of NAD. In the absence of Pi and presence of oligomycin, oxidation of succinate by the alternative cyanide-insensitive oxidase pathway, in the presence of sulfide to inhibit cytochrome oxidase, does not reduce endogenous NAD, either in the aerobic steady state or in anaerobiosis. Under these conditions, only the reversed electron transport pathway from succinate to endogenous NAD is active and ATP cannot interact with the respiratory chain. The source of energy for NAD reduction must come from the respiratory chain, and this result shows that oxidation of succinate through the alternate pathway does not provide this energy. PMID:16657863

  5. Diazotrophic specific cytochrome c oxidase required to overcome light stress in the cyanobacterium Nostoc muscorum.

    PubMed

    Bhargava, Santosh; Chouhan, Shweta

    2016-01-01

    Diazotrophic, filamentous and heterocystous cyanobacterium Nostoc muscorum perform photosynthesis in vegetative whereas nitrogen fixation occurs in heterocyst only. However, despite their metabolic plasticity, respiration takes place both in vegetative cells and heterocysts. The role of the respiratory electron transport system and terminal oxidases under light stress is not evident so far. As compared to the diazotrophically grown cultures, the non-diazotrophically grown cultures of the N. muscorum show a slight decrease in their growth, chlorophyll a contents and photosynthetic O2 evolution under light stress. Whereas respiratory O2 uptake under identical stress condition increases several fold. Likewise, nitrogen fixing enzyme i.e. nitrogenase over-expresses itself under light stress condition. The terminal enzyme of respiratory electron transport chain i.e. cytochrome c oxidase shows more activity under light stress, whilst light stress has no impact on Ca(++)-dependent ATPase activity. This leads to the conclusion that under light stress, cytochrome c oxidase plays a vital role in mitigating given light stress.

  6. Relative contributions of mitochondria and NADPH oxidase to deoxycorticosterone acetate-salt hypertension in mice.

    PubMed

    Zhang, Aihua; Jia, Zhanjun; Wang, Ningning; Tidwell, Tyson J; Yang, Tianxin

    2011-07-01

    We assessed the relative contribution of the mitochondrial respiratory chain and NADPH (nicotinamide adenine dinucleotide phosphate) oxidase to deoxycorticosterone acetate (DOCA)-salt hypertension in mice. The daily mean arterial pressure was monitored by radiotelemetry in DOCA-salt-treated mice given vehicle or the mitochondrial respiratory chain complex I inhibitor rotenone. This treatment produced remarkable attenuation of DOCA-salt hypertension. Similar results were obtained with other inhibitors of mitochondrial function, including 5-hydroxydecanoate (specific for mitochondrial potassium-ATP channels), benzylguanidine (complexes I and III), and the cell-permeable manganese tetrakis (4-benzoic acid) porphyrin (a mimic of mitochondrial superoxide dismutase). In parallel with the blood pressure-lowering effect of rotenone, the DOCA-salt-induced increases in urinary 8-isoprostane excretion and in reactive oxygen species production of isolated kidney mitochondria were both significantly attenuated. Conversely, the DOCA-salt-induced reduction of urinary nitrate/nitrite excretion was significantly elevated. Following DOCA-salt treatment, mice deficient in NADPH oxidase subunits gp91(phox) or p47(phox) exhibited a partial attenuation of the hypertensive response at early but not later time points. Thus, the mitochondrial respiratory chain is a major source of oxidative stress in DOCA-salt hypertension, whereas NADPH oxidase may have a relatively minor role during the early stage of hypertension.

  7. Amplitude-Modulated Bursting: A Novel Class of Bursting Rhythms

    NASA Astrophysics Data System (ADS)

    Vo, Theodore; Kramer, Mark A.; Kaper, Tasso J.

    2016-12-01

    We report on the discovery of a novel class of bursting rhythms, called amplitude-modulated bursting (AMB), in a model for intracellular calcium dynamics. We find that these rhythms are robust and exist on open parameter sets. We develop a new mathematical framework with broad applicability to detect, classify, and rigorously analyze AMB. Here we illustrate this framework in the context of AMB in a model of intracellular calcium dynamics. In the process, we discover a novel family of singularities, called toral folded singularities, which are the organizing centers for the amplitude modulation and exist generically in slow-fast systems with two or more slow variables.

  8. Sympathetic network drive during water deprivation does not increase respiratory or cardiac rhythmic sympathetic nerve activity.

    PubMed

    Holbein, Walter W; Toney, Glenn M

    2013-06-15

    Effects of water deprivation on rhythmic bursting of sympathetic nerve activity (SNA) were investigated in anesthetized, bilaterally vagotomized, euhydrated (control) and 48-h water-deprived (WD) rats (n = 8/group). Control and WD rats had similar baseline values of mean arterial pressure, heart rate, end-tidal CO2, and central respiratory drive. Although integrated splanchnic SNA (sSNA) was greater in WD rats than controls (P < 0.01), analysis of respiratory rhythmic bursting of sSNA revealed that inspiratory rhythmic burst amplitude was actually smaller (P < 0.005) in WD rats (+68 ± 6%) than controls (+208 ± 20%), and amplitudes of the early expiratory (postinspiratory) trough and late expiratory burst of sSNA were not different between groups. Further analysis revealed that water deprivation had no effect on either the amplitude or periodicity of the cardiac rhythmic oscillation of sSNA. Collectively, these data indicate that the increase of sSNA produced by water deprivation is not attributable to either increased respiratory or cardiac rhythmic burst discharge. Thus the sympathetic network response to acute water deprivation appears to differ from that of chronic sympathoexcitation in neurogenic forms of arterial hypertension, where increased respiratory rhythmic bursting of SNA and baroreflex adaptations have been reported.

  9. Cloning and Analysis of the Alternative Oxidase Gene of Neurospora Crassa

    PubMed Central

    Li, Q.; Ritzel, R. G.; McLean, LLT.; McIntosh, L.; Ko, T.; Bertrand, H.; Nargang, F. E.

    1996-01-01

    Mitochondria of Neurospora crassa contain a cyanide-resistant alternative respiratory pathway in addition to the cytochrome pathway. The alternative oxidase is present only when electron flow through the cytochrome chain is restricted. Both genomic and cDNA copies for the alternative oxidase gene have been isolated and analyzed. The sequence of the predicted protein is homologous to that of other species. The mRNA for the alternative oxidase is scarce in wild-type cultures grown under normal conditions, but it is abundant in cultures grown in the presence of chloramphenicol, an inhibitor of mitochondrial protein synthesis, or in mutants deficient in mitochondrial cytochromes. Thus, induction of alternative oxidase appears to be at the transcriptional level. Restriction fragment length polymorphism mapping of the isolated gene demonstrated that it is located in a position corresponding to the aod-1 locus. Sequence analysis of mutant aod-1 alleles reveals mutations affecting the coding sequence of the alternative oxidase. The level of aod-1 mRNA in an aod-2 mutant strain that had been grown in the presence of chloramphenicol was reduced several fold relative to wild-type, supporting the hypothesis that the product of aod-2 is required for optimal expression of aod-1. PMID:8770590

  10. Amyloid-β peptide binds to cytochrome C oxidase subunit 1.

    PubMed

    Hernandez-Zimbron, Luis Fernando; Luna-Muñoz, Jose; Mena, Raul; Vazquez-Ramirez, Ricardo; Kubli-Garfias, Carlos; Cribbs, David H; Manoutcharian, Karen; Gevorkian, Goar

    2012-01-01

    Extracellular and intraneuronal accumulation of amyloid-beta aggregates has been demonstrated to be involved in the pathogenesis of Alzheimer's disease (AD). However, the precise mechanism of amyloid-beta neurotoxicity is not completely understood. Previous studies suggest that binding of amyloid-beta to a number of macromolecules has deleterious effects on cellular functions. Mitochondria were found to be the target for amyloid-beta, and mitochondrial dysfunction is well documented in AD. In the present study we have shown for the first time that Aβ 1-42 bound to a peptide comprising the amino-terminal region of cytochrome c oxidase subunit 1. Phage clone, selected after screening of a human brain cDNA library expressed on M13 phage and bearing a 61 amino acid fragment of cytochrome c oxidase subunit 1, bound to Aβ 1-42 in ELISA as well as to Aβ aggregates present in AD brain. Aβ 1-42 and cytochrome c oxidase subunit 1 co-immunoprecipitated from mitochondrial fraction of differentiated human neuroblastoma cells. Likewise, molecular dynamics simulation of the cytochrome c oxidase subunit 1 and the Aβ 1-42 peptide complex resulted in a reliable helix-helix interaction, supporting the experimental results. The interaction between Aβ 1-42 and cytochrome c oxidase subunit 1 may explain, in part, the diminished enzymatic activity of respiratory chain complex IV and subsequent neuronal metabolic dysfunction observed in AD.

  11. Amyloid-β Peptide Binds to Cytochrome C Oxidase Subunit 1

    PubMed Central

    Hernandez-Zimbron, Luis Fernando; Luna-Muñoz, Jose; Mena, Raul; Vazquez-Ramirez, Ricardo; Kubli-Garfias, Carlos; Cribbs, David H.; Manoutcharian, Karen; Gevorkian, Goar

    2012-01-01

    Extracellular and intraneuronal accumulation of amyloid-beta aggregates has been demonstrated to be involved in the pathogenesis of Alzheimer's disease (AD). However, the precise mechanism of amyloid-beta neurotoxicity is not completely understood. Previous studies suggest that binding of amyloid-beta to a number of macromolecules has deleterious effects on cellular functions. Mitochondria were found to be the target for amyloid-beta, and mitochondrial dysfunction is well documented in AD. In the present study we have shown for the first time that Aβ 1–42 bound to a peptide comprising the amino-terminal region of cytochrome c oxidase subunit 1. Phage clone, selected after screening of a human brain cDNA library expressed on M13 phage and bearing a 61 amino acid fragment of cytochrome c oxidase subunit 1, bound to Aβ 1–42 in ELISA as well as to Aβ aggregates present in AD brain. Aβ 1–42 and cytochrome c oxidase subunit 1 co-immunoprecipitated from mitochondrial fraction of differentiated human neuroblastoma cells. Likewise, molecular dynamics simulation of the cytochrome c oxidase subunit 1 and the Aβ 1–42 peptide complex resulted in a reliable helix-helix interaction, supporting the experimental results. The interaction between Aβ 1–42 and cytochrome c oxidase subunit 1 may explain, in part, the diminished enzymatic activity of respiratory chain complex IV and subsequent neuronal metabolic dysfunction observed in AD. PMID:22927926

  12. Chimera states in bursting neurons

    NASA Astrophysics Data System (ADS)

    Bera, Bidesh K.; Ghosh, Dibakar; Lakshmanan, M.

    2016-01-01

    We study the existence of chimera states in pulse-coupled networks of bursting Hindmarsh-Rose neurons with nonlocal, global, and local (nearest neighbor) couplings. Through a linear stability analysis, we discuss the behavior of the stability function in the incoherent (i.e., disorder), coherent, chimera, and multichimera states. Surprisingly, we find that chimera and multichimera states occur even using local nearest neighbor interaction in a network of identical bursting neurons alone. This is in contrast with the existence of chimera states in populations of nonlocally or globally coupled oscillators. A chemical synaptic coupling function is used which plays a key role in the emergence of chimera states in bursting neurons. The existence of chimera, multichimera, coherent, and disordered states is confirmed by means of the recently introduced statistical measures and mean phase velocity.

  13. Bursts in discontinuous Aeolian saltation

    PubMed Central

    Carneiro, M. V.; Rasmussen, K. R.; Herrmann, H. J.

    2015-01-01

    Close to the onset of Aeolian particle transport through saltation we find in wind tunnel experiments a regime of discontinuous flux characterized by bursts of activity. Scaling laws are observed in the time delay between each burst and in the measurements of the wind fluctuations at the fluid threshold Shields number θc. The time delay between each burst decreases on average with the increase of the Shields number until sand flux becomes continuous. A numerical model for saltation including the wind-entrainment from the turbulent fluctuations can reproduce these observations and gives insight about their origin. We present here also for the first time measurements showing that with feeding it becomes possible to sustain discontinuous flux even below the fluid threshold. PMID:26073305

  14. Monoamine Oxidase Inhibitors: Clinical Review

    PubMed Central

    Remick, Ronald A.; Froese, Colleen

    1990-01-01

    Monoamine oxidase inhibitors (MAOIs) are effective antidepressant agents. They are increasingly and effectively used in a number of other psychiatric and non-psychiatric medical syndromes. Their potential for serious toxicity (i.e., hypertensive reaction) is far less than original reports suggest, and newer reversible substrate-specific MAOIs may offer even less toxicity. The author reviews the pharmacology, mechanism of action, clinical indications, and dosing strategies of MAOIs. The common MAOI side-effects (hypotension, weight gain, sexual dysfunction, insomnia, daytime sedation, myoclonus, and hypertensive episodes) are described and management techniques suggested. Recent clinical developments involving MAOIs are outlined. PMID:21233984

  15. The Swift Burst Alert Telescope

    NASA Astrophysics Data System (ADS)

    Parsons, A.; Barthelmy, S.; Barbier, L.; Gehrels, N.; Palmer, D.; Tueller, J.; Fenimore, E.; BAT Engineering Team

    2000-10-01

    The Swift Gamma Ray Burst MIDEX is a multiwavelength observatory scheduled to be launched in September 2003 to study gamma-ray bursts (GRBs) and their x-ray and optical afterglow emission. Swift will exploit these newly discovered GRB afterglow characteristics to make a comprehensive study of ~ 1000 GRBs and use the afterglow phenomenon as a tool for probing their source and evolution. Swift will also be able to use GRBs to probe the early Universe. The Burst Alert Telescope (BAT), a large coded aperture instrument with a wide field-of-view (FOV), provides the gamma-ray burst triggers and locations for the Swift Mission. BAT will observe and locate hundreds of bursts per year to better than 4 arc minutes accuracy. Using this prompt burst location information, Swift can slew quickly (within 20 - 70 s) to point on-board x-ray (XRT) and optical (UVOT) instrumentation at the burst for continued afterglow studies. The BAT instrument consists of a large (5200 cm2) hard x-ray detector plane positioned one meter away from an even larger (2.6 m2) coded aperture mask. The BAT detector plane consists of 128 CdZnTe semiconductor detector modules each containing 256 individual, planar 4 mm x 4 mm x 2 mm CdZnTe detectors that are read out by a pair of XA1 Application Specific Integrated Circuits (ASICs). The BAT mask will be constructed using 5 mm x 5 mm x 1 mm lead tiles attached to a self-supporting 0.4 g/cm2 substrate fabricated from Kevlar fiber/honeycomb materials. With 4 mm square focal plane detector elements and 5 mm square mask pixels, BAT will have angular resolution better than 22 arc minutes and will determine GRB source locations to ~ 4 arc minutes for bursts detected at 5 sigma or brighter. A full description of the BAT instrument and its capabilities will be presented along with results from performance tests of prototype detector modules.

  16. Resource Sharing Controls Gene Expression Bursting.

    PubMed

    Caveney, Patrick M; Norred, S Elizabeth; Chin, Charles W; Boreyko, Jonathan B; Razooky, Brandon S; Retterer, Scott T; Collier, C Patrick; Simpson, Michael L

    2017-02-17

    Episodic gene expression, with periods of high expression separated by periods of no expression, is a pervasive biological phenomenon. This bursty pattern of expression draws from a finite reservoir of expression machinery in a highly time variant way, i.e., requiring no resources most of the time but drawing heavily on them during short intense bursts, that intimately links expression bursting and resource sharing. Yet, most recent investigations have focused on specific molecular mechanisms intrinsic to the bursty behavior of individual genes, while little is known about the interplay between resource sharing and global expression bursting behavior. Here, we confine Escherichia coli cell extract in both cell-sized microfluidic chambers and lipid-based vesicles to explore how resource sharing influences expression bursting. Interestingly, expression burst size, but not burst frequency, is highly sensitive to the size of the shared transcription and translation resource pools. The intriguing implication of these results is that expression bursts are more readily amplified than initiated, suggesting that burst formation occurs through positive feedback or cooperativity. When extrapolated to prokaryotic cells, these results suggest that large translational bursts may be correlated with large transcriptional bursts. This correlation is supported by recently reported transcription and translation bursting studies in E. coli. The results reported here demonstrate a strong intimate link between global expression burst patterns and resource sharing, and they suggest that bursting plays an important role in optimizing the use of limited, shared expression resources.

  17. WRKY Transcription Factors Phosphorylated by MAPK Regulate a Plant Immune NADPH Oxidase in Nicotiana benthamiana[OPEN

    PubMed Central

    Adachi, Hiroaki; Nakano, Takaaki; Miyagawa, Noriko; Ishihama, Nobuaki; Yoshioka, Miki; Katou, Yuri; Yaeno, Takashi

    2015-01-01

    Pathogen attack sequentially confers pattern-triggered immunity (PTI) and effector-triggered immunity (ETI) after sensing of pathogen patterns and effectors by plant immune receptors, respectively. Reactive oxygen species (ROS) play pivotal roles in PTI and ETI as signaling molecules. Nicotiana benthamiana RBOHB, an NADPH oxidase, is responsible for both the transient PTI ROS burst and the robust ETI ROS burst. Here, we show that RBOHB transactivation mediated by MAPK contributes to R3a/AVR3a-triggered ETI (AVR3a-ETI) ROS burst. RBOHB is markedly induced during the ETI and INF1-triggered PTI (INF1-PTI), but not flg22-tiggered PTI (flg22-PTI). We found that the RBOHB promoter contains a functional W-box in the R3a/AVR3a and INF1 signal-responsive cis-element. Ectopic expression of four phospho-mimicking mutants of WRKY transcription factors, which are MAPK substrates, induced RBOHB, and yeast one-hybrid analysis indicated that these mutants bind to the cis-element. Chromatin immunoprecipitation assays indicated direct binding of the WRKY to the cis-element in plants. Silencing of multiple WRKY genes compromised the upregulation of RBOHB, resulting in impairment of AVR3a-ETI and INF1-PTI ROS bursts, but not the flg22-PTI ROS burst. These results suggest that the MAPK-WRKY pathway is required for AVR3a-ETI and INF1-PTI ROS bursts by activation of RBOHB. PMID:26373453

  18. Immunological comparison of sulfite oxidase

    SciTech Connect

    Pollock, V.; Barber, M.J. )

    1991-03-11

    Polyclonal antibodies (rabbit), elicited against FPLC-purified chicken and rat liver sulfite oxidase (SO), have been examined for inhibition and binding to purified chicken (C), rat (R), bovine (B), alligator (A) and shark (S) liver enzymes. Anti-CSO IgG cross-reacted with all five enzymes, with varying affinities, in the order CSO=ASO{gt}RSO{gt}BSO{gt}SSO. Anti-ROS IgG also cross-reacted with all five enzymes in the order RSO{gt}CSO=ASO{gt}BSO{gt}SSO. Anti-CSO IgG inhibited sulfite:cyt. c reductase (S:CR), sulfite:ferricyanide reductase (S:FR) and sulfite:dichlorophenolindophenol reductase (S:DR) activities of CSO to different extents (S:CR{gt}S:FR=S:DR). Similar differential inhibition was found for anti-ROS IgG and RSO S:CR, S:FR and S:DR activities. Anti-CSO IgG inhibited S:CR activities in the order CSO=ASO{much gt}SSO{gt}BSO. RSO was uninhibited. For anti-RSO IgG the inhibition order was RSO{gt}SSO{gt}BSO{gt}ASO. CSO was uninhibited. Anti-CSO and RSO IgGs partially inhibited Chlorella nitrate reductase (NR). Minor cross-reactivity was found for xanthine oxidase. Common antigenic determinants for all five SO's and NR are indicated.

  19. Cosmology: Home of a fast radio burst

    NASA Astrophysics Data System (ADS)

    Lorimer, Duncan

    2016-02-01

    Our understanding of fast radio bursts -- intense pulses of radio waves -- and their use as cosmic probes promises to be transformed now that one burst has been associated with a galaxy of known distance from Earth. See Letter p.453

  20. Terminal oxidase mutants of the cyanobacterium Synechocystis sp. PCC 6803 show increased electrogenic activity in biological photo-voltaic systems.

    PubMed

    Bradley, Robert W; Bombelli, Paolo; Lea-Smith, David J; Howe, Christopher J

    2013-08-28

    Biological photo-voltaic systems are a type of microbial fuel cell employing photosynthetic microbes at the anode, enabling the direct transduction of light energy to electrical power. Unlike the anaerobic bacteria found in conventional microbial fuel cells that use metals in the environment as terminal electron acceptors, oxygenic photosynthetic organisms are poorly adapted for electron transfer out of the cell. Mutant strains of the cyanobacterium Synechocystis sp. PCC 6803 were created in which all combinations of the three respiratory terminal oxidase complexes had been inactivated. These strains were screened for the ability to reduce the membrane-impermeable soluble electron acceptor ferricyanide, and the results were compared to the performance of the mutants in a biological photo-voltaic system. Deletion of the two thylakoid-localised terminal oxidases, the bd-quinol oxidase and cytochrome c oxidase resulted in a 16-fold increase in ferricyanide reduction rate in the dark compared to the wild-type. A further improvement to a 24-fold increase was seen upon deletion of the remaining "alternative respiratory terminal oxidase". These increases were reflected in the peak power generated in the biological photo-voltaic systems. Inactivation of all three terminal oxidase complexes resulted in a substantial redirection of reducing power; in the dark the equivalent of 10% of the respiratory electron flux was channelled to ferricyanide, compared to less than 0.2% in the wild-type. Only minor improvements in ferricyanide reduction rates over the wild-type were seen in illuminated conditions, where carbon dioxide is preferentially used as an electron sink. This study demonstrates the potential for optimising photosynthetic microbes for direct electrical current production.

  1. Gamma-ray burst observations

    NASA Technical Reports Server (NTRS)

    Atteia, J.-L.

    1993-01-01

    The most important observational characteristics of gamma-ray bursts are reviewed, with emphasis on X-ray and gamma-ray data. The observations are used to derive some basic properties of the sources. The sources are found to be isotropically distributed; the burster population is limited in space, and the edge of the distribution is visible.

  2. The Mystery of Gamma-Ray Bursts

    NASA Technical Reports Server (NTRS)

    Fishman, Gerald J.

    1998-01-01

    Gamma-ray bursts remain on of the greatest mysteries in astrophysics in spite of recent observational advances and intense theoretical work. Although some of the basic properties of bursts were known 25 years ago, new and more detailed observations have been made by the BATSE (Burst and Transient Source Experiment) experiment on the Compton Gamma Ray Observatory in the past five years. Recent observations of bursts and some proposed models will be discussed.

  3. Alternative oxidase in animals: unique characteristics and taxonomic distribution.

    PubMed

    McDonald, Allison E; Vanlerberghe, Greg C; Staples, James F

    2009-08-01

    Alternative oxidase (AOX), a ubiquinol oxidase, introduces a branch point into the respiratory electron transport chain, bypassing complexes III and IV and resulting in cyanide-resistant respiration. Previously, AOX was thought to be limited to plants and some fungi and protists but recent work has demonstrated the presence of AOX in most kingdoms of life, including animals. In the present study we identified AOX in 28 animal species representing nine phyla. This expands the known taxonomic distribution of AOX in animals by 10 species and two phyla. Using bioinformatics we found AOX gene sequences in members of the animal phyla Porifera, Placozoa, Cnidaria, Mollusca, Annelida, Nematoda, Echinodermata, Hemichordata and Chordata. Using reverse-transcriptase polymerase chain reaction (RT-PCR) with degenerate primers designed to recognize conserved regions of animal AOX, we demonstrated that AOX genes are transcribed in several animals from different phyla. An analysis of full-length AOX sequences revealed an amino acid motif in the C-terminal region of the protein that is unique to animal AOXs. Animal AOX also lacks an N-terminal cysteine residue that is known to be important for AOX enzyme regulation in plants. We conclude that the presence of AOX is the ancestral state in animals and hypothesize that its absence in some lineages, including vertebrates, is due to gene loss events.

  4. Data on cytochrome c oxidase assembly in mice and human fibroblasts or tissues induced by SURF1 defect.

    PubMed

    Kovářová, Nikola; Pecina, Petr; Nůsková, Hana; Vrbacký, Marek; Zeviani, Massimo; Mráček, Tomáš; Viscomi, Carlo; Houštěk, Josef

    2016-06-01

    This paper describes data related to a research article entitled "Tissue- and species-specific differences in cytochrome c oxidase assembly induced by SURF1 defects" [1]. This paper includes data of the quantitative analysis of individual forms of respiratory chain complexes I, III and IV present in SURF1 knockout (SURF1 (-/-) ) and control (SURF1 (+/+) ) mouse fibroblasts and tissues and in fibroblasts of human control and patients with SURF1 gene mutation. Also it includes data demonstrating response of complex IV, cytochrome c oxidase (COX), to reversible inhibition of mitochondrial translation in SURF1 (-/-) mouse and SURF1 patient fibroblast cell lines.

  5. Involvement of alternative oxidase in the regulation of sensitivity of Sclerotinia sclerotiorum to the fungicides azoxystrobin and procymidone.

    PubMed

    Xu, Ting; Wang, Ya-Ting; Liang, Wu-Sheng; Yao, Fei; Li, Yong-Hong; Li, Dian-Rong; Wang, Hao; Wang, Zheng-Yi

    2013-06-01

    Sclerotinia sclerotiorum is a filamentous fungal pathogen that can infect many economically important crops and vegetables. Alternative oxidase is the terminal oxidase of the alternative respiratory pathway in fungal mitochondria. The function of alternative oxidase was investigated in the regulation of sensitivity of S. sclerotiorum to two commercial fungicides, azoxystrobin and procymidone which have different fungitoxic mechanisms. Two isolates of S. sclerotiorum were sensitive to both fungicides. Application of salicylhydroxamic acid, a specific inhibitor of alternative oxidase, significantly increased the values of effective concentration causing 50% mycelial growth inhibition (EC50) of azoxystrobin to both S. sclerotiorum isolates, whereas notably decreased the EC50 values of procymidone. In mycelial respiration assay azoxystrobin displayed immediate inhibitory effect on cytochrome pathway capacity, but had no immediate effect on alternative pathway capacity. In contrast, procymidone showed no immediate impact on capacities of both cytochrome and alternative pathways in the mycelia. However, alternative oxidase encoding gene (aox) transcript and protein levels, alternative respiration pathway capacity of the mycelia were obviously increased by pre-treatment for 24 h with both azoxystrobin and procymidone. These results indicate that alternative oxidase was involved in the regulation of sensitivity of S. sclerotiorum to the fungicides azoxystrobin and procymidone, and that both fungicides could affect aox gene expression and the alternative respiration pathway capacity development in mycelia of this fungal pathogen.

  6. Relationship of cytochrome caa sub 3 from Thermus thermophilus to other heme- and copper-containing terminal oxidases

    SciTech Connect

    Mather, M.W.; Springer, P.; Fee, J.A.

    1990-01-01

    Cytochrome oxidases are a key component of the energy metabolism of most aerobic organisms from mammals to bacteria. They are the final enzyme of the membrane associated respiratory chain responsible for converting the chemical energy of reduced substrates to a transmembrane electrochemical potential, which issused by the cell for a wide variety of energy-requiring processes. The most widely studied oxidase is the cytochrome c oxidase of the mammalian mitochondrion. This complex, integral membrane protein contains 13 subunits and four canonical metal centers: heme center a and a{sub 3}; copper centers CU{sub A} and CU{sub B}. It is responsible for electron transfer from reduced chytochrome c to dioxygen with the concomitant reduction of dioxygen to water and the coupled vectorial transfer of protons across the mitochondrial membrane. In this communication we will describe preliminary results of DNA sequencing experiments with the cytochrome caa{sub 3} oxidase, initially undertaken to determine the nature of the subunits of this oxidase and shed light on the distribution of the metal centers. We will speculate on oxidase gene and protein structures and evolutionary relationships in the light of these results and recent sequencing results from other groups. 47 refs., 4 figs., 1 tab.

  7. Comparison of brain mitochondrial cytochrome c oxidase activity with cyanide LD(50) yields insight into the efficacy of prophylactics.

    PubMed

    Marziaz, Mandy L; Frazier, Kathryn; Guidry, Paul B; Ruiz, Robyn A; Petrikovics, Ilona; Haines, Donovan C

    2013-01-01

    Cyanide inhibits cytochrome c oxidase, the terminal oxidase of the mitochondrial respiratory pathway, therefore inhibiting the cell oxygen utilization and resulting in the condition of histotoxic anoxia. The enzyme rhodanese detoxifies cyanide by utilizing sulfur donors to convert cyanide to thiocyanate, and new and improved sulfur donors are actively sought as researchers seek to improve cyanide prophylactics. We have determined brain cytochrome c oxidase activity as a marker for cyanide exposure for mice pre-treated with various cyanide poisoning prophylactics, including sulfur donors thiosulfate (TS) and thiotaurine (TT3). Brain mitochondria were isolated by differential centrifugation, the outer mitochondrial membrane was disrupted by a maltoside detergent, and the decrease in absorbance at 550 nm as horse heart ferrocytochrome c (generated by the dithiothreitol reduction of ferricytochrome c) was oxidized was monitored. Overall, the TS control prophylactic treatment provided significant protection of the cytochrome c oxidase activity. The TT3-treated mice showed reduced cytochrome c oxidase activity even in the absence of cyanide. In both treatment series, addition of exogenous Rh did not significantly enhance the prevention of cytochrome c oxidase inhibition, but the addition of sodium nitrite did. These findings can lead to a better understanding of the protection mechanism by various cyanide antidotal systems.

  8. The Mystery of Gamma-Ray Bursts

    NASA Technical Reports Server (NTRS)

    Fishman, Gerald J.

    2004-01-01

    Gamma-ray bursts remain one of the greatest mysteries in astrophysics. Observations of gamma-ray bursts made by the BATSE experiment on the Compton Gamma-Ray Observatory will be described. Most workers in the field now believe that they originate from cosmological distances. This view has been reinforced by observations this year of several optical afterglow counterparts to gamma-ray bursts. A summary of these recent discoveries will be presented, along with their implications for models of the burst emission mechanism and the energy source of the bursts.

  9. Metabolic control analysis of the bc1 complex of Saccharomyces cerevisiae: effect on cytochrome c oxidase, respiration and growth rate.

    PubMed Central

    Boumans, H; Berden, J A; Grivell, L A; van Dam, K

    1998-01-01

    A number of strains varying in steady-state level of assembled bc1 complex were used to test the conclusions from inhibitor titration experiments with isolated mitochondria that, in cells of Saccharomyces cerevisiae grown on non-fermentable carbon sources, the control coefficient of the bc1 complex on the mitochondrial respiratory capacity equals 1 and the respiratory chain consists of supermolecular respiratory units [Boumans, Grivell and Berden (1998) J. Biol. Chem. 273, 4872-4877]. In addition, the control coefficient of mitochondrial respiration on the growth rate was determined. It was found that a reduced level of bc1 complex is accompanied by an almost parallel decrease in steady-state level of cytochrome c oxidase. Since the linear relationship between level of active bc1 complex and respiratory capacity still holds, it is concluded that cytochrome c oxidase has disappeared from respiratory units that are already deficient in the bc1 complex and that the cytochrome c oxidase in a respiratory unit is destabilized when the bc1 complex is deficient. The control coefficient of the bc1 complex, and thus of mitochondrial electron-transfer capacity, on respiration of intact cells (without uncoupler added) is 0.20. Addition of uncoupler results in an increase in the coefficient to 0.36. Thus changing the respiratory state changes the distribution of control, increasing the control coefficient of electron-transfer activity as the respiratory state goes towards State 3u. Rates of growth of the strains on different carbon sources were determined and subsequently fitted to calculate control coefficients of the bc1 complex (and therefore of the respiratory capacity) on growth. Little variation was found between lactate-, ethanol- and glycerol-containing media, control coefficients being around 0.18 at pH 5. At pH 7 the control coefficient increased to 0.57, indicative of a higher dependence of the cell on ATP derived from oxidative phosphorylation. During growth on

  10. Solar Radio Bursts and Space Weather

    NASA Technical Reports Server (NTRS)

    Gopalswamy, Natchimuthuk,

    2012-01-01

    Radio bursts from the Sun are produced by electron accelerated to relativistic energies by physical processes on the Sun such as solar flares and coronal mass ejections (CMEs). The radio bursts are thus good indicators of solar eruptions. Three types of nonthermal radio bursts are generally associated with CMEs. Type III bursts due to accelerated electrons propagating along open magnetic field lines. The electrons are thought to be accelerated at the reconnection region beneath the erupting CME, although there is another view that the electrons may be accelerated at the CME-driven shock. Type II bursts are due to electrons accelerated at the shock front. Type II bursts are also excellent indicators of solar energetic particle (SEP) events because the same shock is supposed accelerate electrons and ions. There is a hierarchical relationship between the wavelength range of type /I bursts and the CME kinetic energy. Finally, Type IV bursts are due to electrons trapped in moving or stationary structures. The low frequency stationary type IV bursts are observed occasionally in association with very fast CMEs. These bursts originate from flare loops behind the erupting CME and hence indicate tall loops. This paper presents a summary of radio bursts and their relation to CMEs and how they can be useful for space weather predictions.

  11. Observations of Gamma-Ray Bursts

    NASA Technical Reports Server (NTRS)

    Fishman, G. J.

    1995-01-01

    Some basic observed properties of gamma-ray bursts are reviewed. Although some properties were known 25 years ago, new and more detailed observations have been made by the Compton Observatory in the past three years. The new observation with the greatest impact has been the observed isotropic distribution of bursts along with a deficiency of weak bursts which would be expected from a homogeneous burst distribution. This is not compatible with any known Galactic population of objects. Gamma-ray bursts show an enormous variety of burst morphologies and a wide spread in burst durations. The spectra of gamma-ray bursts are characterized by rapid variations and peak power which is almost entirely in the gamma-ray energy range. Delayed gamma-ray burst photons extending to GeV energies have been detected for the first time. A time dilation effect has also been reported to be observed in gamma-ray, bursts. The observation of a gamma-ray burst counterpart in another wavelength region has yet to be made.

  12. Dietary inhibitors of monoamine oxidase A.

    PubMed

    Dixon Clarke, Sarah E; Ramsay, Rona R

    2011-07-01

    Inhibition of monoamine oxidase is one way to treat depression and anxiety. The information now available on the pharmacokinetics of flavonoids and of the components of tobacco prompted an exploration of whether a healthy diet (with or without smoking) provides active compounds in amounts sufficient to partially inhibit monoamine oxidase. A literature search was used to identify dietary monoamine oxidase inhibitors, the levels of these compounds in foods, the pharmacokinetics of the absorption and distribution, and tissue levels observed. An estimated daily intake and the expected tissue concentrations were compared with the measured efficacies of the compounds as inhibitors of monoamine oxidases. Norharman, harman and quercetin dietary presence, pharmacokinetics, and tissue levels were consistent with significant levels reaching neuronal monoamine oxidase from the diet or smoking; 1,2,3,4-tetrahydroisoquinoline, eugenol, 1-piperoylpiperidine, and coumarin were not. Quercetin was equipotent with norharman as a monoamine oxidase A inhibitor and its metabolite, isorhamnetin, also inhibits. Total quercetin was the highest of the compounds in the sample diet. Although bioavailability was variable depending on the source, a healthy diet contains amounts of quercetin that might give sufficient amounts in brain to induce, by monoamine oxidase A inhibition, a small decrease in neurotransmitter breakdown.

  13. Inactivation of the Pseudomonas putida cytochrome o ubiquinol oxidase leads to a significant change in the transcriptome and to increased expression of the CIO and cbb3-1 terminal oxidases.

    PubMed

    Morales, Gracia; Ugidos, Ana; Rojo, Fernando

    2006-10-01

    Pseudomonas putida KT2440 contains a branched aerobic respiratory chain with several terminal oxidases. Inactivation of the cyo terminal ubiquinol oxidase has little effect on growth rate but is known to relieve the inhibition by global control that modulates induction of genes required to assimilate alkanes in cells growing in the presence of preferred carbon sources. We show that inactivation of other terminal oxidases has no effect on regulation of the alkane degradation pathway, which points to cyo as the oxidase that transmits a regulatory signal related to the activity of the electron transport chain. Using a genome-wide DNA microarray we found that inactivation of cyo has a significant effect on the transcriptome, supporting that it participates in global regulation of gene expression. Among the genes affected stand out those coding for transporters of organic acids, porins, transcriptional regulators and terminal oxidases. Real-time reverse transcription polymerase chain reaction (RT-PCR) showed that, in cells growing exponentially in a complete medium, the absence of cyo was compensated by increased expression of the cyanide-insensitive and cbb3-1 terminal oxidases, while cbb3-2 and aa3 oxidases remained unaffected. When cells enter into stationary phase cyo levels decrease and inhibition of the alkane degradation genes ceases. This was paralleled by upregulation of the cyanide-insensitive, cbb3-1, cbb3-2 and aa3 terminal oxidases. The results suggest that P. putida adapts the composition of the electron transport chain not only to optimize energy generation, but also to influence the transcriptome profile of the cell through global control of gene expression.

  14. Do gamma-ray burst sources repeat?

    NASA Technical Reports Server (NTRS)

    Meegan, Charles A.; Hartmann, Dieter H.; Brainerd, J. J.; Briggs, Michael S.; Paciesas, William S.; Pendleton, Geoffrey; Kouveliotou, Chryssa; Fishman, Gerald; Blumenthal, George; Brock, Martin

    1995-01-01

    The demonstration of repeated gamma-ray bursts from an individual source would severely constrain burst source models. Recent reports (Quashnock and Lamb, 1993; Wang and Lingenfelter, 1993) of evidence for repetition in the first BATSE burst catalog have generated renewed interest in this issue. Here, we analyze the angular distribution of 585 bursts of the second BATSE catalog (Meegan et al., 1994). We search for evidence of burst recurrence using the nearest and farthest neighbor statistic and the two-point angular correlation function. We find the data to be consistent with the hypothesis that burst sources do not repeat; however, a repeater fraction of up to about 20% of the observed bursts cannot be excluded.

  15. Structural insights into sulfite oxidase deficiency.

    PubMed

    Karakas, Erkan; Wilson, Heather L; Graf, Tyler N; Xiang, Song; Jaramillo-Busquets, Sandra; Rajagopalan, K V; Kisker, Caroline

    2005-09-30

    Sulfite oxidase deficiency is a lethal genetic disease that results from defects either in the genes encoding proteins involved in molybdenum cofactor biosynthesis or in the sulfite oxidase gene itself. Several point mutations in the sulfite oxidase gene have been identified from patients suffering from this disease worldwide. Although detailed biochemical analyses have been carried out on these mutations, no structural data could be obtained because of problems in crystallizing recombinant human and rat sulfite oxidases and the failure to clone the chicken sulfite oxidase gene. We synthesized the gene for chicken sulfite oxidase de novo, working backward from the amino acid sequence of the native chicken liver enzyme by PCR amplification of a series of 72 overlapping primers. The recombinant protein displayed the characteristic absorption spectrum of sulfite oxidase and exhibited steady state and rapid kinetic parameters comparable with those of the tissue-derived enzyme. We solved the crystal structures of the wild type and the sulfite oxidase deficiency-causing R138Q (R160Q in humans) variant of recombinant chicken sulfite oxidase in the resting and sulfate-bound forms. Significant alterations in the substrate-binding pocket were detected in the structure of the mutant, and a comparison between the wild type and mutant protein revealed that the active site residue Arg-450 adopts different conformations in the presence and absence of bound sulfate. The size of the binding pocket is thereby considerably reduced, and its position relative to the cofactor is shifted, causing an increase in the distance of the sulfur atom of the bound sulfate to the molybdenum.

  16. Genistein effect on xanthine oxidase activity.

    PubMed

    Sumbayev, V V

    2001-01-01

    Genistein was defined to be an allosteric xanthine oxidase inhibitor in the concentrations 0.1-4.0 microM and xanthine oxidase activator with superoxide scavenging activity in the concentrations 5.0 microM and higher. But the most effective allosteric binding with the highest affinity was observed in the genistein concentrations 0.1-1.0 microM. Intraperitoneum injections of genistein (500 micrograms/kg) during three days with the interval 24 hours decrease xanthine oxidase activity in the liver, lung and brain of the Vistar rats.

  17. Upper respiratory tract (image)

    MedlinePlus

    The major passages and structures of the upper respiratory tract include the nose or nostrils, nasal cavity, mouth, throat (pharynx), and voice box (larynx). The respiratory system is lined with a mucous membrane that ...

  18. Avian respiratory system disorders

    USGS Publications Warehouse

    Olsen, G.H.

    1989-01-01

    Diagnosing and treating respiratory diseases in avian species requires a basic knowledge about the anatomy and physiology of this system in birds. Differences between mammalian and avian respiratory system function, diagnosis, and treatment are highlighted.

  19. MSFC Respiratory Protection Services

    NASA Technical Reports Server (NTRS)

    CoVan, James P.

    1999-01-01

    An overview of the Marshall Space Flight Center Respiratory Protection program is provided in this poster display. Respiratory protection personnel, building, facilities, equipment, customers, maintenance and operational activities, and Dynatech fit testing details are described and illustrated.

  20. Phasic Motor Activity of Respiratory and Non-Respiratory Muscles in REM Sleep

    PubMed Central

    Fraigne, Jimmy J.; Orem, John M.

    2011-01-01

    Objectives: In this study, we quantified the profiles of phasic activity in respiratory muscles (diaphragm, genioglossus and external intercostal) and non-respiratory muscles (neck and extensor digitorum) across REM sleep. We hypothesized that if there is a unique pontine structure that controls all REM sleep phasic events, the profiles of the phasic twitches of different muscle groups should be identical. Furthermore, we described how respiratory parameters (e.g., frequency, amplitude, and effort) vary across REM sleep to determine if phasic processes affect breathing. Methods: Electrodes were implanted in Wistar rats to record brain activity and muscle activity of neck, extensor digitorum, diaphragm, external intercostal, and genioglossal muscles. Ten rats were studied to obtain 313 REM periods over 73 recording days. Data were analyzed offline and REM sleep activity profiles were built for each muscle. In 6 animals, respiratory frequency, effort, amplitude, and inspiratory peak were also analyzed during 192 REM sleep periods. Results: Respiratory muscle phasic activity increased in the second part of the REM period. For example, genioglossal activity increased in the second part of the REM period by 63.8% compared to the average level during NREM sleep. This profile was consistent between animals and REM periods (η2 = 0.58). This increased activity seen in respiratory muscles appeared as irregular bursts and trains of activity that could affect rythmo-genesis. Indeed, the increased integrated activity seen in the second part of the REM period in the diaphragm was associated with an increase in the number (28.3%) and amplitude (30%) of breaths. Non-respiratory muscle phasic activity in REM sleep did not have a profile like the phasic activity of respiratory muscles. Time in REM sleep did not have an effect on nuchal activity (P = 0.59). Conclusion: We conclude that the concept of a common pontine center controlling all REM phasic events is not supported by our

  1. Cytochrome c oxidase loses catalytic activity and structural integrity during the aging process in Drosophila melanogaster

    SciTech Connect

    Ren, Jian-Ching; Rebrin, Igor; Klichko, Vladimir; Orr, William C.; Sohal, Rajindar S.

    2010-10-08

    Research highlights: {yields} Cytochrome c oxidase loses catalytic activity during the aging process. {yields} Abundance of seven nuclear-encoded subunits of cytochrome c oxidase decreased with age in Drosophila. {yields} Cytochrome c oxidase is specific intra-mitochondrial site of age-related deterioration. -- Abstract: The hypothesis, that structural deterioration of cytochrome c oxidase (CcO) is a causal factor in the age-related decline in mitochondrial respiratory activity and an increase in H{sub 2}O{sub 2} generation, was tested in Drosophila melanogaster. CcO activity and the levels of seven different nuclear DNA-encoded CcO subunits were determined at three different stages of adult life, namely, young-, middle-, and old-age. CcO activity declined progressively with age by 33%. Western blot analysis, using antibodies specific to Drosophila CcO subunits IV, Va, Vb, VIb, VIc, VIIc, and VIII, indicated that the abundance these polypeptides decreased, ranging from 11% to 40%, during aging. These and previous results suggest that CcO is a specific intra-mitochondrial site of age-related deterioration, which may have a broad impact on mitochondrial physiology.

  2. Respiratory Syncytial Virus

    MedlinePlus

    ... Your 1- to 2-Year-Old Respiratory Syncytial Virus KidsHealth > For Parents > Respiratory Syncytial Virus A A A What's in this article? About ... RSV When to Call the Doctor en español Virus respiratorio sincitial About RSV Respiratory syncytial (sin-SISH- ...

  3. Lungs and Respiratory System

    MedlinePlus

    ... A Week of Healthy Breakfasts Shyness Lungs and Respiratory System KidsHealth > For Teens > Lungs and Respiratory System Print ... didn't breathe, you couldn't live. Lungs & Respiratory System Basics Each day we breathe about 20,000 ...

  4. Lungs and Respiratory System

    MedlinePlus

    ... A Week of Healthy Breakfasts Shyness Lungs and Respiratory System KidsHealth > For Teens > Lungs and Respiratory System A ... didn't breathe, you couldn't live. Lungs & Respiratory System Basics Each day we breathe about 20,000 ...

  5. Prokaryotic origins for the mitochondrial alternative oxidase and plastid terminal oxidase nuclear genes.

    PubMed

    Finnegan, Patrick M; Umbach, Ann L; Wilce, Jackie A

    2003-12-18

    The mitochondrial alternative oxidase is a diiron carboxylate quinol oxidase (Dox) found in plants and some fungi and protists, but not animals. The plastid terminal oxidase is distantly related to alternative oxidase and is most likely also a Dox protein. Database searches revealed that the alpha-proteobacterium Novosphingobium aromaticivorans and the cyanobacteria Nostoc sp. PCC7120, Synechococcus sp. WH8102 and Prochlorococcus marinus subsp. pastoris CCMP1378 each possess a Dox homolog. Each prokaryotic protein conforms to the current structural models of the Dox active site and phylogenetic analyses suggest that the eukaryotic Dox genes arose from an ancestral prokaryotic gene.

  6. Proton slippage in cytochrome c oxidase of Paracoccus denitrificans. Membrane-potential measurements with the two-subunit and three-subunit enzyme.

    PubMed

    Steverding, D; Köhnke, D; Ludwig, B; Kadenbach, B

    1993-03-15

    Isolated cytochrome c oxidase from Paracoccus denitrificans, containing either two or three subunits, was reconstituted into liposomes and the membrane potential was measured at different rates of respiration using a triphenylmethylphosponium bromide electrode. Both enzymes revealed a non-linear increase of the membrane potential with increasing respiratory rates. The ratios of the respiratory rates of the two proton pumps decreased with increasing membrane potential, suggesting slippage of proton pumping, as has been shown before with two cytochrome c oxidases from bovine heart, differing in H+/e- stoichiometries due to chemical modification [Steverding, D. & Kadenbach, B. (1991) J. Biol. Chem. 266, 8097-8101]. The data suggest that slippage of proton pumping represents an intrinsic property of cytochrome c oxidase associated with the two catalytic subunits, I and II.

  7. Activation of polyphenol oxidase of chloroplasts.

    PubMed

    Tolbert, N E

    1973-02-01

    Polyphenol oxidase of leaves is located mainly in chloroplasts isolated by differential or sucrose density gradient centrifugation. This activity is part of the lamellar structure that is not lost on repeated washing of the plastids. The oxidase activity was stable during prolonged storage of the particles at 4 C or -18 C. The Km (dihydroxyphenylalanine) for spinach leaf polyphenol oxidase was 7 mm by a spectrophotometric assay and 2 mm by the manometric assay. Polyphenol oxidase activity in the leaf peroxisomal fraction, after isopycnic centrifugation on a linear sucrose gradient, did not coincide with the peroxisomal enzymes but was attributed to proplastids at nearly the same specific density.Plants were grouped by the latency properties for polyphenol oxidase in their isolated chloroplasts. In a group including spinach, Swiss chard, and beet leaves the plastids immediately after preparation from fresh leaves required a small amount of light for maximal rates of oxidation of dihydroxyphenylalanine. Polyphenol oxidase activity in the dark or light increased many fold during aging of these chloroplasts for 1 to 5 days. Soluble polyphenol oxidase of the cytoplasm was not so stimulated. Chloroplasts prepared from stored leaves were also much more active than from fresh leaves. Maximum rates of dihydroxyphenylalanine oxidation were 2 to 6 mmoles x mg(-1) chlorophyll x hr(-1). Equal stimulation of latent polyphenol oxidase in fresh or aged chloroplasts in this group was obtained by either light, an aged trypsin digest, 3-(4-chlorophenyl)-1, 1-dimethylurea, or antimycin A. A variety of other treatments did not activate or had little effect on the oxidase, including various peptides, salts, detergents, and other proteolytic enzymes.Activation of latent polyphenol oxidase in spinach chloroplasts by trypsin amounted to as much as 30-fold. The trypsin activation occurred even after the trypsin had been treated with 10% trichloroacetic acid, 1.0 n HCl or boiled for 30

  8. Characteristics of cytochrome oxidase activity in visual system neurons in kittens reared in conditions of flashing illumination.

    PubMed

    Merkul'eva, N S; Makarov, F N

    2005-10-01

    The studies reported here addressed the effects of flashing (15 Hz) lights on the metabolic activity of visual system neurons in animals reared in condition of crepuscular illumination. Activity of the respiratory enzyme cytochrome oxidase was detected in the cortex of visual areas 17 and 18 and in the lateral geniculate body in kittens. The results showed that kittens subjected to this stimulation, unlike intact kittens and kittens reared in conditions of crepuscular illumination, showed a change in the pattern of cytochrome oxidase distribution in cortical field 17 consisting of the appearance of alternating areas of increased and decreased enzyme activity in layers III and IV. In cortical field 18 and the lateral geniculate body, experimental kittens showed no changes in the cytochrome oxidase activity distribution pattern. It is suggested that flashing illumination leads to disturbance of the balance in activity in the Y and X conducting channels of the visual system.

  9. [Peculiarities of cytochrome oxidase activity in the visual cortex neurons of kittens reared under the conditions of flickering illumination].

    PubMed

    Merkul'eva, N S; Makarov, F N

    2004-01-01

    The objective of this study was to analyze the influence of the light flickering with the frequency of 15 Hz, on the neuronal metabolic activity in kittens reared under the conditions of mesopic illumination. The method for demonstration of a respiratory enzyme cytochrome oxidase was used to study the visual cortex areas 17 and 18 and the lateral geniculate nucleus. It was shown that in kittens that were subjected to this stimulation as opposed to intact animals and to kittens reared under the conditions of mesopic illumination, specific changes in pattern of cytochrome oxidase distribution in area 17 took place. This change was manifested by the appearance of alternating zones of increased and decreased enzyme activity in layers III and IV. Within the cortical area 18 and lateral geniculate nucleus, no changes in the pattern of cytochrome oxidase activity distribution were detected in experimental kittens. It is suggested that flickering illumination results in disequilibrium of Y- and X-visual pathway activity.

  10. [Music and respiratory pathology].

    PubMed

    Herer, B

    2001-04-01

    Musical performance, especially in singers and wind instrument players, depends on an effective pulmonary function. Performing artists may be seriously impaired by respiratory diseases that, comparatively, may produce only modest inconvenience for non-musicians. The report of two cases of respiratory diseases occurring in musicians herein provides an introduction to a review of the interactions between music and the human respiratory system. The following points are considered: epidemiological data; pulmonary function in musicians; favorable effects of music on the respiratory system; description of the main respiratory problems that may affect musicians.

  11. Azide inhibition of urate oxidase.

    PubMed

    Gabison, Laure; Colloc'h, Nathalie; Prangé, Thierry

    2014-07-01

    The inhibition of urate oxidase (UOX) by azide was investigated by X-ray diffraction techniques and compared with cyanide inhibition. Two well characterized sites for reagents are present in the enzyme: the dioxygen site and the substrate-binding site. To examine the selectivity of these sites towards azide inhibition, several crystallization conditions were developed. UOX was co-crystallized with azide (N3) in the presence or absence of either uric acid (UA, the natural substrate) or 8-azaxanthine (8AZA, a competitive inhibitor). In a second set of experiments, previously grown orthorhombic crystals of the UOX-UA or UOX-8AZA complexes were soaked in sodium azide solutions. In a third set of experiments, orthorhombic crystals of UOX with the exchangeable ligand 8-nitroxanthine (8NXN) were soaked in a solution containing uric acid and azide simultaneously (competitive soaking). In all assays, the soaking periods were either short (a few hours) or long (one or two months). These different experimental conditions showed that one or other of the sites, or the two sites together, could be inhibited. This also demonstrated that azide not only competes with dioxygen as cyanide does but also competes with the substrate for its enzymatic site. A model in agreement with experimental data would be an azide in equilibrium between two sites, kinetically in favour of the dioxygen site and thermodynamically in favour of the substrate-binding site.

  12. Azide inhibition of urate oxidase

    PubMed Central

    Gabison, Laure; Colloc’h, Nathalie; Prangé, Thierry

    2014-01-01

    The inhibition of urate oxidase (UOX) by azide was investigated by X-ray diffraction techniques and compared with cyanide inhibition. Two well characterized sites for reagents are present in the enzyme: the dioxygen site and the substrate-binding site. To examine the selectivity of these sites towards azide inhibition, several crystallization conditions were developed. UOX was co-crystallized with azide (N3) in the presence or absence of either uric acid (UA, the natural substrate) or 8-azaxanthine (8AZA, a competitive inhibitor). In a second set of experiments, previously grown orthorhombic crystals of the UOX–UA or UOX–8AZA complexes were soaked in sodium azide solutions. In a third set of experiments, orthorhombic crystals of UOX with the exchangeable ligand 8-nitroxanthine (8NXN) were soaked in a solution containing uric acid and azide simultaneously (competitive soaking). In all assays, the soaking periods were either short (a few hours) or long (one or two months). These different experimental conditions showed that one or other of the sites, or the two sites together, could be inhibited. This also demonstrated that azide not only competes with dioxygen as cyanide does but also competes with the substrate for its enzymatic site. A model in agreement with experimental data would be an azide in equilibrium between two sites, kinetically in favour of the dioxygen site and thermodynamically in favour of the substrate-binding site. PMID:25005084

  13. The plastid terminal oxidase: its elusive function points to multiple contributions to plastid physiology.

    PubMed

    Nawrocki, Wojciech J; Tourasse, Nicolas J; Taly, Antoine; Rappaport, Fabrice; Wollman, Francis-André

    2015-01-01

    Plastids have retained from their cyanobacterial ancestor a fragment of the respiratory electron chain comprising an NADPH dehydrogenase and a diiron oxidase, which sustain the so-called chlororespiration pathway. Despite its very low turnover rates compared with photosynthetic electron flow, knocking out the plastid terminal oxidase (PTOX) in plants or microalgae leads to severe phenotypes that encompass developmental and growth defects together with increased photosensitivity. On the basis of a phylogenetic and structural analysis of the enzyme, we discuss its physiological contribution to chloroplast metabolism, with an emphasis on its critical function in setting the redox poise of the chloroplast stroma in darkness. The emerging picture of PTOX is that of an enzyme at the crossroads of a variety of metabolic processes, such as, among others, the regulation of cyclic electron transfer and carotenoid biosynthesis, which have in common their dependence on the redox state of the plastoquinone pool, set largely by the activity of PTOX in darkness.

  14. Flexibility in photosynthetic electron transport: a newly identified chloroplast oxidase involved in chlororespiration.

    PubMed

    Cournac, L; Josse, E M; Joët, T; Rumeau, D; Redding, K; Kuntz, M; Peltier, G

    2000-10-29

    Besides electron transfer reactions involved in the 'Z' scheme of photosynthesis, alternative electron transfer pathways have been characterized in chloroplasts. These include cyclic electron flow around photosystem I (PS I) or a respiratory chain called chlororespiration. Recent work has supplied new information concerning the molecular nature of the electron carriers involved in the non-photochemical reduction of the plastoquinone (PQ) pool. However, until now little is known concerning the nature of the electron carriers involved in PQ oxidation. By using mass spectrometric measurement of oxygen exchange performed in the presence of 18O-enriched O2 and Chlamydomonas mutants deficient in PS I, we show that electrons can be directed to a quinol oxidase sensitive to propyl gallate but insensitive to salicyl hydroxamic acid. This oxidase has immunological and pharmacological similarities with a plastid protein involved in carotenoid biosynthesis.

  15. Three brainstem areas involved in respiratory rhythm generation in bullfrogs

    PubMed Central

    Baghdadwala, Mufaddal I; Duchcherer, Maryana; Paramonov, Jenny; Wilson, Richard J A

    2015-01-01

    an additional brainstem region that generates the priming phase. This Priming Area extends rostral and caudal of the Lung Area and is distinct from the Buccal Area. Using AMPA microinjections and reversible synaptic blockade, we demonstrate selective excitation and ablation (respectively) of priming phase activity. We also demonstrate that the Priming Area contains neurons active selectively during the priming phase. Thus, we propose that three distinct neuronal components generate the multiphase respiratory motor pattern produced by the frog brainstem: the buccal, priming and powerstroke burst generators. This raises the possibility that a similar multi-burst generator architecture mediates the three distinct phases of ventilation in mammals. PMID:25952282

  16. Stirling Colgate and Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Lamb, Donald

    2014-10-01

    Even before the discovery of gamma-ray bursts (GRBs), Stirling Colgate proposed that bursts of x rays and gamma rays might be produced by a relativistic shock created in the supernova explosion of a massive star. We trace the scientific story of GRBs from their detection to the present, highlighting along the way Stirling's interest in them and his efforts to understand them. We summarize our current understanding that short, soft, repeating bursts are produced by magnetic neutron stars; short, hard bursts are produced by the mergers of neutron star-neutron star binaries; and long, hard bursts are produced by the core collapse of massive stars that have lost their hydrogen and helium envelopes. We then discuss some important open questions about GRBs and how they might be answered. We conclude by describing the recent serendipitous discovery of an x-ray burst of exactly the kind he proposed, and the insights into core collapse supernovae and GRBs that it provided.

  17. Hardness/intensity correlations among BATSE bursts

    NASA Technical Reports Server (NTRS)

    Paciesas, William S.; Pendleton, Geoffrey N.; Kouveliotou, Chryssa; Fishman, Gerald J.; Meegan, Charles A.; Wilson, Robert B.

    1992-01-01

    Conclusions about the nature of gamma-ray bursts derived from the size-frequency distribution may be altered if a significant correlation exists between burst intensity and spectral shape. Moreover, if gamma-ray bursts have a cosmological origin, such a correlation may be expected to result from the expansion of the universe. We have performed a rudimentary search of the BATSE bursts for hardness/intensity correlations. The range of spectral shapes was determined for each burst by computing the ratio of the intensity in the range 100-300 keV to that in 55-300 keV. We find weak evidence for the existence of a correlation, the strongest effect being present when comparing the maximum hardness ratio for each burst with its maximum rate.

  18. Burst interference in TDMA radio systems

    NASA Astrophysics Data System (ADS)

    Lei, Z.; Chen, M.-X.; Feher, K.

    Analytical and experimental studies show that burst interference in TDMA systems causes spectral spreading, which depends on the gating rate and duty cycle of the burst. A probability-of-error performance study of IJF (intersymbol and jitter-free) OQPSK systems in the presence of burst interference signals shows that the higher gating rate or smaller duty cycle of the burst will introduce more degradation because of increased spectral spreading. It is concluded that the transmitted power of the burst signal should be limited more strictly than that of CW signals, because the burst interference causes more degradation in the performance of the desired channel than nonburst interference with the same (C/I)mean.

  19. Transitions to Synchrony in Coupled Bursting Neurons

    NASA Astrophysics Data System (ADS)

    Dhamala, Mukeshwar; Jirsa, Viktor K.; Ding, Mingzhou

    2004-01-01

    Certain cells in the brain, for example, thalamic neurons during sleep, show spike-burst activity. We study such spike-burst neural activity and the transitions to a synchronized state using a model of coupled bursting neurons. In an electrically coupled network, we show that the increase of coupling strength increases incoherence first and then induces two different transitions to synchronized states, one associated with bursts and the other with spikes. These sequential transitions to synchronized states are determined by the zero crossings of the maximum transverse Lyapunov exponents. These results suggest that synchronization of spike-burst activity is a multi-time-scale phenomenon and burst synchrony is a precursor to spike synchrony.

  20. ArxA, a new clade of arsenite oxidase within the DMSO reductase family of molybdenum oxidoreductases

    USGS Publications Warehouse

    Zargar, Kamrun; Conrad, Alison; Bernick, David L.; Lowe, Todd M.; Stolc, Viktor; Hoeft, Shelley; Oremland, Ronald S.; Stolz, John; Saltikov, Chad W.

    2012-01-01

    Arsenotrophy, growth coupled to autotrophic arsenite oxidation or arsenate respiratory reduction, occurs only in the prokaryotic domain of life. The enzymes responsible for arsenotrophy belong to distinct clades within the DMSO reductase family of molybdenum-containing oxidoreductases: specifically arsenate respiratory reductase, ArrA, and arsenite oxidase, AioA (formerly referred to as AroA and AoxB). A new arsenite oxidase clade, ArxA, represented by the haloalkaliphilic bacterium Alkalilimnicola ehrlichii strain MLHE-1 was also identified in the photosynthetic purple sulfur bacterium Ectothiorhodospira sp. strain PHS-1. A draft genome sequence of PHS-1 was completed and an arx operon similar to MLHE-1 was identified. Gene expression studies showed that arxA was strongly induced with arsenite. Microbial ecology investigation led to the identification of additional arxA-like sequences in Mono Lake and Hot Creek sediments, both arsenic-rich environments in California. Phylogenetic analyses placed these sequences as distinct members of the ArxA clade of arsenite oxidases. ArxA-like sequences were also identified in metagenome sequences of several alkaline microbial mat environments of Yellowstone National Park hot springs. These results suggest that ArxA-type arsenite oxidases appear to be widely distributed in the environment presenting an opportunity for further investigations of the contribution of Arx-dependent arsenotrophy to the arsenic biogeochemical cycle.

  1. Spectral features of solar gradual microwave bursts.

    NASA Astrophysics Data System (ADS)

    Yao, J.-X.

    The author presents data and spectral analysis of five solar gradual microwave bursts (GMB's), which are associated with the gradual hard X-ray bursts (GHB's). The durations of GMB's are about tens of minutes and are longer than that of impulsive bursts (5 min.) and the sources of GMB's are high in the corona. Therefore, one may attribute the long durations and spectral index decrease to the high radio sources.

  2. Ceramic Matrix Composite Vane Subelement Burst Testing

    NASA Technical Reports Server (NTRS)

    Brewer, David N.; Verrilli, Michael; Calomino, Anthony

    2006-01-01

    Burst tests were performed on Ceramic Matrix Composite (CMC) vane specimens, manufactured by two vendors, under the Ultra Efficient Engine Technology (UEET) project. Burst specimens were machined from the ends of 76mm long vane sub-elements blanks and from High Pressure Burner Rig (HPBR) tested specimens. The results of burst tests will be used to compare virgin specimens with specimens that have had an Environmental Barrier Coating (EBC) applied, both HPBR tested and untested, as well as a comparison between vendors.

  3. A Gamma-Ray Burst Trigger Toolkit

    NASA Technical Reports Server (NTRS)

    Band, David L.; White, Nicholas E. (Technical Monitor)

    2002-01-01

    The detection rate of a gamma-ray burst detector can be increased by using a count rate trigger with many accumulation times DELTAt and energy bands DELTAE Because a burst's peak flux varies when averaged over different DELTAt and DELTAE the nominal sensitivity (the numerical value of the peak flux) of a trigger system is less important than how much fainter a burst could be at the detection threshold as DELTAt and DELTAE are changed. The relative sensitivity of different triggers can be quantified by referencing the detection threshold back to the peak flux for a fiducial value of DELTAt and DELTA E. This mapping between peak flux values for different sets of DELTAt and DELTAE varies from burst to burst. Quantitative estimates of the burst detection rate for a given detector and trigger system can be based on the observed rate at a measured peak flux value in this fiducial trigger. Predictions of a proposed trigger's burst detection rate depend on the assumed burst population, and these predictions can be wildly in error for triggers that differ significantly from previous missions. I base the fiducial rate on the BATSE observations: 550 bursts per sky above a peak flux of 0.3 ph per square centimeter per second averaged over DELTAt=1.024 sec and DELTAE=50-300 keV. Using a sample of 100 burst lightcurves I find that triggering on any value of DELTAt that is a multiple of 0.064 sec decreases the average threshold peak flux on the 1.024 sec timescale by a factor of 0.6. Extending DELTAE to lower energies includes the large flux of the X-ray background, increasing the background count rate. Consequently a low energy DELTAE is advantageous only for very soft bursts. Whether a large fraction of the population of bright bursts is soft is disputed; the new population of X-ray Flashes is soft but relatively faint.

  4. Ballerina - pirouettes in search of gamma bursts

    NASA Astrophysics Data System (ADS)

    Brandt, S.; Lund, N.; Pedersen, H.; Hjorth, J.; BALLERINA Collaboration

    1999-09-01

    The cosmological origin of gamma ray bursts has now been established with reasonable certainty. Many more bursts will need to be studied to establish the typical distance scale, and to map out the large diversity in properties which have been indicated by the first handful of events. We are proposing Ballerina, a small satellite to provide accurate positions and new data on the gamma-ray bursts. We anticipate a detection rate an order of magnitude larger than obtained from Beppo-SAX.

  5. ASPARTATE OXIDASE Plays an Important Role in Arabidopsis Stomatal Immunity1[W][OA

    PubMed Central

    Macho, Alberto P.; Boutrot, Freddy; Rathjen, John P.; Zipfel, Cyril

    2012-01-01

    Perception of pathogen-associated molecular patterns (PAMPs), such as bacterial flagellin (or the peptide flg22), by surface-localized receptors activates defense responses and subsequent immunity. In a previous forward-genetic screen aimed at the identification of Arabidopsis (Arabidopsis thaliana) flagellin-insensitive (fin) mutants, we isolated fin4, which is severely affected in flg22-triggered reactive oxygen species (ROS) bursts. Here, we report that FIN4 encodes the chloroplastic enzyme ASPARTATE OXIDASE (AO), which catalyzes the first irreversible step in the de novo biosynthesis of NAD. Genetic studies on the role of NAD have been hindered so far by the lethality of null mutants in NAD biosynthetic enzymes. Using newly identified knockdown fin alleles, we found that AO is required for the ROS burst mediated by the NADPH oxidase RBOHD triggered by the perception of several unrelated PAMPs. AO is also required for RBOHD-dependent stomatal closure. However, full AO activity is not required for flg22-induced responses that are RBOHD independent. Interestingly, although the fin4 mutation dramatically affects RBOHD function, it does not affect functions carried out by other members of the RBOH family, such as RBOHC and RBOHF. Finally, we determined that AO is required for stomatal immunity against the bacterium Pseudomonas syringae. Altogether, our work reveals a novel specific requirement for AO activity in PAMP-triggered RBOHD-dependent ROS burst and stomatal immunity. In addition, the availability of viable mutants for the chloroplastic enzyme AO will enable future detailed studies on the role of NAD metabolism in different cellular processes, including immunity, in Arabidopsis. PMID:22730426

  6. Helium bubble bursting in tungsten

    SciTech Connect

    Sefta, Faiza; Juslin, Niklas; Wirth, Brian D.

    2013-12-28

    Molecular dynamics simulations have been used to systematically study the pressure evolution and bursting behavior of sub-surface helium bubbles and the resulting tungsten surface morphology. This study specifically investigates how bubble shape and size, temperature, tungsten surface orientation, and ligament thickness above the bubble influence bubble stability and surface evolution. The tungsten surface is roughened by a combination of adatom “islands,” craters, and pinholes. The present study provides insight into the mechanisms and conditions leading to various tungsten topology changes, which we believe are the initial stages of surface evolution leading to the formation of nanoscale fuzz.

  7. Bursts in inclined layer convection

    NASA Astrophysics Data System (ADS)

    Busse, F. H.; Clever, R. M.

    2000-08-01

    A new instability of longitudinal rolls in an inclined fluid layer heated from below is analyzed in the case of the Prandtl number P=0.71. The instability assumes the form of subharmonic undulations and evolves into a spatially chaotic pattern when the angle of inclination is of the order of 20°. The chaotic state rapidly decays and longitudinal rolls recover until the next burst of chaotic convection occurs. The theoretical findings closely correspond to recent experimental observations by Daniels et al. [Phys. Rev. Lett. (to be published)].

  8. The mitochondrial respiratory chain of Ustilago maydis.

    PubMed

    Juárez, Oscar; Guerra, Guadalupe; Martínez, Federico; Pardo, Juan Pablo

    2004-10-04

    Ustilago maydis mitochondria contain the four classical components of the electron transport chain (complexes I, II, III, and IV), a glycerol phosphate dehydrogenase, and two alternative elements: an external rotenone-insensitive flavone-sensitive NADH dehydrogenase (NDH-2) and an alternative oxidase (AOX). The external NDH-2 contributes as much as complex I to the NADH-dependent respiratory activity, and is not modulated by Ca2+, a regulatory mechanism described for plant NDH-2, and presumed to be a unique characteristic of the external isozyme. The AOX accounts for the 20% residual respiratory activity after inhibition of complex IV by cyanide. This residual activity depends on growth conditions, since cells grown in the presence of cyanide or antimycin A increase its proportion to about 75% of the uninhibited rate. The effect of AMP, pyruvate and DTT on AOX was studied. The activity of AOX in U. maydis cells was sensitive to AMP but not to pyruvate, which agrees with the regulatory characteristics of a fungal AOX. Interestingly, the presence of DTT during cell permeabilisation protected the enzyme against inactivation. The pathways of quinone reduction and quinol oxidation lack an additive behavior. This is consistent with the competition of the respiratory components of each pathway for the quinol/quinone pool.

  9. Neutron Stars and Thermonuclear X-ray Bursts

    NASA Technical Reports Server (NTRS)

    Bhattacharyya, Supid

    2007-01-01

    This viewgraph presentation describes neutron stars and thermonuclear x ray bursts. The contents include: 1) Neutron Stars: why do we care?; 2) Thermonuclear Bursts: why do we care?; 3) Neutron Stars: Mass, Radius and Spin: a. Continuum Spectroscopy of Bursts b. Spectral Lines from Bursts c. Timing Properties of Bursts; 4) Neutron Star Atmosphere: Thermonuclear Flame Spreading; and 5) Future Prospects and Conclusions.

  10. Transcriptional burst frequency and burst size are equally modulated across the human genome

    SciTech Connect

    Dar, Roy D.; Simpson, Michael L; Weinberger, Leor S.; Razooky, B; Cox, Chris D.; McCollum, James M.; Trimeloni, Tom; Singh, A

    2012-01-01

    Gene expression occurs either as an episodic process, characterized by pulsatile bursts or as a constitutive, Poisson-like accumulation of gene products. It is not clear which mode of gene expression (constitutive versus bursty) predominates across a genome or how transcriptional dynamics are influenced by genomic position and promoter sequence. Here, we use time-lapse fluorescence microscopy, building off of theoretical studies that exploit the time-resolved structure of stochastic fluctuations in gene expression, to develop a three-dimensional method for mapping underlying gene-regulatory mechanisms. Over 8,000 individual human genomic loci were analyzed, and at virtually all loci, episodic bursting as opposed to constitutive expression was found to be the predominant mode of expression. Quantitative analysis of the expression dynamics at these 8,000 loci indicates that both frequency and size of transcriptional bursts vary equally across the human genome independent of promoter sequence. Strikingly, weaker expression loci modulate burst frequency to increase activity, while stronger expression loci modulate burst size to increase activity. Transcriptional activators, such as TNF, generate similar patterns of change in burst frequency and burst size. In summary, transcriptional bursting dominates across the human genome, both burst frequency and burst size vary by chromosomal location, and transcriptional activators alter burst frequency and burst size, depending on the expression level of the locus.

  11. NADPH oxidase expression in active multiple sclerosis lesions in relation to oxidative tissue damage and mitochondrial injury.

    PubMed

    Fischer, Marie T; Sharma, Rakhi; Lim, Jamie L; Haider, Lukas; Frischer, Josa M; Drexhage, Joost; Mahad, Don; Bradl, Monika; van Horssen, Jack; Lassmann, Hans

    2012-03-01

    Multiple sclerosis is a chronic inflammatory disease of the central nervous system, associated with demyelination and neurodegeneration. The mechanisms of tissue injury are poorly understood, but recent data suggest that mitochondrial injury may play an important role in this process. Mitochondrial injury can be triggered by reactive oxygen and nitric oxide species, and we recently provided evidence for oxidative damage of oligodendrocytes and dystrophic axons in early stages of active multiple sclerosis lesions. In this study, we identified potential sources of reactive oxygen and nitrogen species through gene expression in carefully staged and dissected lesion areas and by immunohistochemical analysis of protein expression. Genome-wide microarrays confirmed mitochondrial injury in active multiple sclerosis lesions, which may serve as an important source of reactive oxygen species. In addition, we found differences in the gene expression levels of various nicotinamide adenine dinucleotide phosphate oxidase subunits between initial multiple sclerosis lesions and control white matter. These results were confirmed at the protein level by means of immunohistochemistry, showing upregulation of the subunits gp91phox, p22phox, p47phox, nicotinamide adenine dinucleotide phosphate oxidase 1 and nicotinamide adenine dinucleotide phosphate oxidase organizer 1 in activated microglia in classical active as well as slowly expanding lesions. The subunits gp91phox and p22phox were constitutively expressed in microglia and were upregulated in the initial lesion. In contrast, p47phox, nicotinamide adenine dinucleotide phosphate oxidase 1 and nicotinamide adenine dinucleotide phosphate oxidase organizer 1 expression were more restricted to the zone of initial damage or to lesions from patients with acute or early relapsing/remitting multiple sclerosis. Double labelling showed co-expression of the nicotinamide adenine dinucleotide phosphate oxidase subunits in activated microglia and

  12. NADPH oxidase expression in active multiple sclerosis lesions in relation to oxidative tissue damage and mitochondrial injury

    PubMed Central

    Fischer, Marie T.; Sharma, Rakhi; Lim, Jamie L.; Haider, Lukas; Frischer, Josa M.; Drexhage, Joost; Mahad, Don; Bradl, Monika; van Horssen, Jack

    2012-01-01

    Multiple sclerosis is a chronic inflammatory disease of the central nervous system, associated with demyelination and neurodegeneration. The mechanisms of tissue injury are poorly understood, but recent data suggest that mitochondrial injury may play an important role in this process. Mitochondrial injury can be triggered by reactive oxygen and nitric oxide species, and we recently provided evidence for oxidative damage of oligodendrocytes and dystrophic axons in early stages of active multiple sclerosis lesions. In this study, we identified potential sources of reactive oxygen and nitrogen species through gene expression in carefully staged and dissected lesion areas and by immunohistochemical analysis of protein expression. Genome-wide microarrays confirmed mitochondrial injury in active multiple sclerosis lesions, which may serve as an important source of reactive oxygen species. In addition, we found differences in the gene expression levels of various nicotinamide adenine dinucleotide phosphate oxidase subunits between initial multiple sclerosis lesions and control white matter. These results were confirmed at the protein level by means of immunohistochemistry, showing upregulation of the subunits gp91phox, p22phox, p47phox, nicotinamide adenine dinucleotide phosphate oxidase 1 and nicotinamide adenine dinucleotide phosphate oxidase organizer 1 in activated microglia in classical active as well as slowly expanding lesions. The subunits gp91phox and p22phox were constitutively expressed in microglia and were upregulated in the initial lesion. In contrast, p47phox, nicotinamide adenine dinucleotide phosphate oxidase 1 and nicotinamide adenine dinucleotide phosphate oxidase organizer 1 expression were more restricted to the zone of initial damage or to lesions from patients with acute or early relapsing/remitting multiple sclerosis. Double labelling showed co-expression of the nicotinamide adenine dinucleotide phosphate oxidase subunits in activated microglia and

  13. Early steps in the oxidative burst induced by cadmium in cultured tobacco cells (BY-2 line).

    PubMed

    Olmos, Enrique; Martínez-Solano, Juan R; Piqueras, Abel; Hellín, Eladio

    2003-01-01

    The rapid generation of H(2)O(2) by Cd(2+)-treated plant cells was investigated in cultured tobacco (Nicotiana tabacum L.) BY-2 cells. The starting point for the generation of H(2)O(2) has been located at the cell plasma membrane using cytochemical methods. Treatment of the cells with diphenyleneiodonium (DPI) and imidazol, both inhibitors of the neutrophil NADPH oxidase, prevented the generation of H(2)O(2) induced by Cd(2+). These data suggest the involvement of an NADPH oxidase-like enzyme leading to H(2)O(2) production through O(2)(*-) dismutation by superoxide dismutase enzymes. To investigate the implication of Ca(2+) channels in a Cd(2+)-induced oxidative burst, different inhibitors of Ca(2+) channels were used. Only La(3+) totally inhibited the generation of H(2)O(2) induced by Cd(2+). However, verapamil and nifedipine, inhibitors of Ca(2+) channels, were not effective. Calmodulin or a Ca(2+)-dependent protein kinase is also implicated in the signal transduction sequence, based on the results obtained with two types of calmodulin antagonists, fluphenazine and N-(-6-amino-hexyl)-5-chloro-1-naphthalenesulphonamide (W-7) and staurosporine, an inhibitor of protein kinases. However, neomycin, an inhibitor of the phosphoinositide cycle, did not inhibit the generation of H(2)O(2) induced by Cd(2+), suggesting mainly an induction of the oxidative burst mediated by calmodulin and/or calmodulin-dependent proteins.

  14. Proton exit channels in bovine cytochrome c oxidase.

    PubMed

    Popović, Dragan M; Stuchebrukhov, Alexei A

    2005-02-10

    Cytochrome c oxidase (CcO) is the terminal transmembrane enzyme of the respiratory electron transport chain in aerobic cells. It catalyzes the reduction of oxygen to water and utilizes the free energy of the reduction reaction for proton pumping, a process which results in a membrane electrochemical proton gradient. Although the structure of the enzyme has been solved for several organisms, the molecular mechanism of proton pumping and proton exit pathways remain unknown. In our previous work, the continuum electrostatic calculations were employed to evaluate the electrostatic potential, energies, and protonation state of bovine cytochrome c oxidase for different redox states of the enzyme. A possible mechanism of oxygen reduction and proton pumping via His291 was proposed. In this paper, using electrostatic calculations, we examine the proton exit pathways in the enzyme. By monitoring the changes of the protonation states, proton affinities, and energies of electrostatic interactions between the titratable groups in different redox states of CcO, we identified the clusters of strongly interacting residues. Using these data, we detected four possible proton exit points on the periplasmic side of the membrane (Lys171B/Asp173B, His24B/Asp25B, Asp51, and Asp300). We then were able to trace the proton exit pathways and to evaluate the energy profiles along the paths. On the basis of energetic considerations and the conservation of the residues in a protein sequence, the most likely exit pathway is one via the Lys171B/Asp173B site. The obtained results are fully consistent with our His291 model of proton pumping, and provide a rationale for the absence of proton leaking in CcO between the pumping strokes.

  15. Derived amino acid sequences of the nosZ gene (respiratory N2O reductase) from Alcaligenes eutrophus, Pseudomonas aeruginosa and Pseudomonas stutzeri reveal potential copper-binding residues. Implications for the CuA site of N2O reductase and cytochrome-c oxidase.

    PubMed

    Zumft, W G; Dreusch, A; Löchelt, S; Cuypers, H; Friedrich, B; Schneider, B

    1992-08-15

    The nosZ genes encoding the multicopper enzyme nitrous oxide reductase of Alcaligenes eutrophus H16 and the type strain of Pseudomonas aeruginosa were cloned and sequenced for structural comparison of their gene products with the homologous product of the nosZ gene from Pseudomonas stutzeri [Viebrock, A. & Zumft, W. G. (1988) J. Bacteriol. 170, 4658-4668] and the subunit II of cytochrome-c oxidase (COII). Both types of enzymes possess the CuA binding site. The nosZ genes were identified in cosmid libraries by hybridization with an internal 1.22-kb PstI fragment (NS220) of nosZ from P. stutzeri. The derived amino acid sequences indicate unprocessed gene products of 70084 Da (A. eutrophus) and 70695 Da (P. aeruginosa). The N-terminal sequences of the NosZ proteins have the characteristics of signal peptides for transport. A homologous domain, extending over at least 50 residues, is shared among the three derived NosZ sequences and the CuA binding region of 32 COII sequences. Only three out of nine cysteine residues of the NosZ protein (P. stutzeri) are invariant. Cys618 and Cys622 are assigned to a binuclear center, A, which is thought to represent the CuA site of NosZ and is located close to the C terminus. Two conserved histidines, one methionine, one aspartate, one valine and two aromatic residues are also part of the CuA consensus sequence, which is the domain homologous between the two enzymes. The CuA consensus sequence, however, lacks four strictly conserved residues present in all COII sequences. Cys165 is likely to be a ligand of a second binuclear center, Z, for which we assume mainly histidine coordination. Of 23 histidine residues in NosZ (P. stutzeri), 14 are invariant, 7 of which are in regions with a degree of conservation well above the 50% positional identity between the Alcaligenes and Pseudomonas sequences. Conserved tryptophan residues are located close to several potential copper ligands. Trp615 may contribute to the observed quenching of

  16. Role of apoptosis-inducing factor, proline dehydrogenase, and NADPH oxidase in apoptosis and oxidative stress

    PubMed Central

    Natarajan, Sathish Kumar; Becker, Donald F

    2012-01-01

    Flavoproteins catalyze a variety of reactions utilizing flavin mononucleotide or flavin adenine dinucleotide as cofactors. The oxidoreductase properties of flavoenzymes implicate them in redox homeostasis, oxidative stress, and various cellular processes, including programmed cell death. Here we explore three critical flavoproteins involved in apoptosis and redox signaling, ie, apoptosis-inducing factor (AIF), proline dehydrogenase, and NADPH oxidase. These proteins have diverse biochemical functions and influence apoptotic signaling by unique mechanisms. The role of AIF in apoptotic signaling is two-fold, with AIF changing intracellular location from the inner mitochondrial membrane space to the nucleus upon exposure of cells to apoptotic stimuli. In the mitochondria, AIF enhances mitochondrial bioenergetics and complex I activity/assembly to help maintain proper cellular redox homeostasis. After translocating to the nucleus, AIF forms a chromatin degrading complex with other proteins, such as cyclophilin A. AIF translocation from the mitochondria to the nucleus is triggered by oxidative stress, implicating AIF as a mitochondrial redox sensor. Proline dehydrogenase is a membrane-associated flavoenzyme in the mitochondrion that catalyzes the rate-limiting step of proline oxidation. Upregulation of proline dehydrogenase by the tumor suppressor, p53, leads to enhanced mitochondrial reactive oxygen species that induce the intrinsic apoptotic pathway. NADPH oxidases are a group of enzymes that generate reactive oxygen species for oxidative stress and signaling purposes. Upon activation, NADPH oxidase 2 generates a burst of superoxide in neutrophils that leads to killing of microbes during phagocytosis. NADPH oxidases also participate in redox signaling that involves hydrogen peroxide-mediated activation of different pathways regulating cell proliferation and cell death. Potential therapeutic strategies for each enzyme are also highlighted. PMID:22593641

  17. Early complications. Respiratory failure.

    PubMed

    Zwischenberger, J B; Alpard, S K; Bidani, A

    1999-08-01

    Pulmonary complications following thoracic surgery are common and associated with significant morbidity and mortality. Respiratory failure after pneumonectomy occurs in approximately 5% to 15% of cases and significantly increases patient mortality. Strategies for ventilator support are based on the nature of the underlying complication and the pathophysiology of respiratory failure. This article describes the cause and pathophysiology of respiratory failure and pulmonary embolus postpneumonectomy. Diagnosis, management, and innovative therapies are also reviewed.

  18. Air bubble bursting effect of lotus leaf.

    PubMed

    Wang, Jingming; Zheng, Yongmei; Nie, Fu-Qiang; Zhai, Jin; Jiang, Lei

    2009-12-15

    In this paper, a phenomenon of air bubbles quickly bursting within several milliseconds on a "self-cleaning" lotus leaf was described. This observation prompted the synthesis of artificial surfaces similar to that of the lotus leaf. The artificial leaf surfaces, prepared by photolithography and wet etching, showed a similar air bubble bursting effect. Smooth and rough silicon surfaces with an ordered nanostructure or patterned microstructure were utilized to study the contribution of the micro/nano hierarchical structures to this phenomenon of air bubble bursting. Air bubbles were found to burst on some superhydrophobic surfaces with microstructure (within 220 ms). However, air bubbles burst much more rapidly (within 13 ms) on similar surfaces with micro/nanostructure. The height, width, and spacing of hierarchical structures could also affect air bubble bursting, and the effect of the height was more obvious. When the height of hierarchical structures was around the height found in natural lotus papillae, the width and spacing were significant for air bubble bursting. An original model was proposed to further evaluate the reason why the micro/nano hierarchical rough structures had an excellent air bubble bursting effect, and the validity of the model was theoretically demonstrated.

  19. Backscattering of solar electron burst distributions

    NASA Astrophysics Data System (ADS)

    Skoug, R. M.; Steinberg, J. T.; Anderson, B. R.; de Koning, C. A.; Gosling, J. T.; McComas, D. J.

    2008-12-01

    Solar electron bursts are frequently observed in the ACE/SWEPAM suprathermal electron measurements at energies below 1.4 keV. Approximately 1/3 of such events show backstreaming electrons, which are typically observed after a 1-2 hour delay following burst onset and travel back towards the Sun along the magnetic field direction. These backstreaming particles are likely produced by scattering of the solar electron burst particles beyond the ~1 AU spacecraft location. Our previous studies have shown that transient solar burst electrons exhibit a greater degree of pitch angle scattering than does the steady-state solar wind electron strahl, which could result in turning back of the burst electrons. From the delays observed between the onset of the bursts and the backstreaming, we infer that burst electrons are turned back sunward at a field-aligned distance of less than 1 AU beyond the spacecraft. In this study we compare the fluxes and energy spectra of backstreaming particles with those of the outgoing burst particles. In addition, we compare the angular widths of the two electron beams. These comparisons provide an indication of the relative importance of magnetic mirroring and focusing, scattering in pitch angle, and scattering in energy for determining the character of the observed electron distributions.

  20. Astronomy: Radio burst caught red-handed

    NASA Astrophysics Data System (ADS)

    Falcke, Heino

    2017-01-01

    For almost a decade, astronomers have observed intense bursts of radio waves from the distant cosmos whose origins were unknown. The source of one such burst has now been identified, but this has only deepened the mystery. See Letter p.58

  1. The Burst Mode of Protostellar Accretion

    NASA Astrophysics Data System (ADS)

    Vorobyov, E. I.; Basu, Shantanu

    2006-10-01

    We present new numerical simulations in the thin disk approximation that characterize the burst mode of protostellar accretion. The burst mode begins upon the formation of a centrifugally balanced disk around a newly formed protostar. It comprises prolonged quiescent periods of low accretion rate (typically <~10-7 Msolar yr-1) that are punctuated by intense bursts of accretion (typically >~10-4 Msolar yr-1, with duration <~100 yr) during which most of the protostellar mass is accumulated. The accretion bursts are associated with the formation of dense protostellar/protoplanetary embryos, which are later driven onto the protostar by the gravitational torques that develop in the disk. Gravitational instability in the disk, driven by continuing infall from the envelope, is shown to be an effective means of transporting angular momentum outward and mass inward to the protostar. We show that the disk mass always remains significantly less than the central protostar's mass throughout this process. The burst phenomenon is robust enough to occur for a variety of initial values of rotation rate and frozen-in (supercritical) magnetic field and a variety of density-temperature relations. Even in cases where the bursts are nearly entirely suppressed, a moderate increase in cloud size or rotation rate can lead to vigorous burst activity. We conclude that most (if not all) protostars undergo a burst mode of evolution during their early accretion history, as inferred empirically from observations of FU Orionis variables.

  2. Physics issues of gamma ray burst emissions

    NASA Technical Reports Server (NTRS)

    Liang, Edison

    1987-01-01

    The critical physics issues in the interpretation of gamma-ray-burst spectra are reviewed. An attempt is made to define the emission-region parameter space satisfying the maximum number of observational and theoretical constraints. Also discussed are the physical mechanisms responsible for the bursts that are most consistent with the above parameter space.

  3. Autaptic Connections Shift Network Excitability and Bursting

    PubMed Central

    Wiles, Laura; Gu, Shi; Pasqualetti, Fabio; Parvesse, Brandon; Gabrieli, David; Bassett, Danielle S.; Meaney, David F.

    2017-01-01

    We examine the role of structural autapses, when a neuron synapses onto itself, in driving network-wide bursting behavior. Using a simple spiking model of neuronal activity, we study how autaptic connections affect activity patterns, and evaluate if controllability significantly affects changes in bursting from autaptic connections. Adding more autaptic connections to excitatory neurons increased the number of spiking events and the number of network-wide bursts. We observed excitatory synapses contributed more to bursting behavior than inhibitory synapses. We evaluated if neurons with high average controllability, predicted to push the network into easily achievable states, affected bursting behavior differently than neurons with high modal controllability, thought to influence the network into difficult to reach states. Results show autaptic connections to excitatory neurons with high average controllability led to higher burst frequencies than adding the same number of self-looping connections to neurons with high modal controllability. The number of autapses required to induce bursting was lowered by adding autapses to high degree excitatory neurons. These results suggest a role of autaptic connections in controlling network-wide bursts in diverse cortical and subcortical regions of mammalian brain. Moreover, they open up new avenues for the study of dynamic neurophysiological correlates of structural controllability. PMID:28266594

  4. The human respiratory gate

    NASA Technical Reports Server (NTRS)

    Eckberg, Dwain L.

    2003-01-01

    Respiratory activity phasically alters membrane potentials of preganglionic vagal and sympathetic motoneurones and continuously modulates their responsiveness to stimulatory inputs. The most obvious manifestation of this 'respiratory gating' is respiratory sinus arrhythmia, the rhythmic fluctuations of electrocardiographic R-R intervals observed in healthy resting humans. Phasic autonomic motoneurone firing, reflecting the throughput of the system, depends importantly on the intensity of stimulatory inputs, such that when levels of stimulation are low (as with high arterial pressure and sympathetic activity, or low arterial pressure and vagal activity), respiratory fluctuations of sympathetic or vagal firing are also low. The respiratory gate has a finite capacity, and high levels of stimulation override the ability of respiration to gate autonomic responsiveness. Autonomic throughput also depends importantly on other factors, including especially, the frequency of breathing, the rate at which the gate opens and closes. Respiratory sinus arrhythmia is small at rapid, and large at slow breathing rates. The strong correlation between systolic pressure and R-R intervals at respiratory frequencies reflects the influence of respiration on these two measures, rather than arterial baroreflex physiology. A wide range of evidence suggests that respiratory activity gates the timing of autonomic motoneurone firing, but does not influence its tonic level. I propose that the most enduring significance of respiratory gating is its use as a precisely controlled experimental tool to tease out and better understand otherwise inaccessible human autonomic neurophysiological mechanisms.

  5. Burst suppression probability algorithms: state-space methods for tracking EEG burst suppression

    NASA Astrophysics Data System (ADS)

    Chemali, Jessica; Ching, ShiNung; Purdon, Patrick L.; Solt, Ken; Brown, Emery N.

    2013-10-01

    Objective. Burst suppression is an electroencephalogram pattern in which bursts of electrical activity alternate with an isoelectric state. This pattern is commonly seen in states of severely reduced brain activity such as profound general anesthesia, anoxic brain injuries, hypothermia and certain developmental disorders. Devising accurate, reliable ways to quantify burst suppression is an important clinical and research problem. Although thresholding and segmentation algorithms readily identify burst suppression periods, analysis algorithms require long intervals of data to characterize burst suppression at a given time and provide no framework for statistical inference. Approach. We introduce the concept of the burst suppression probability (BSP) to define the brain's instantaneous propensity of being in the suppressed state. To conduct dynamic analyses of burst suppression we propose a state-space model in which the observation process is a binomial model and the state equation is a Gaussian random walk. We estimate the model using an approximate expectation maximization algorithm and illustrate its application in the analysis of rodent burst suppression recordings under general anesthesia and a patient during induction of controlled hypothermia. Main result. The BSP algorithms track burst suppression on a second-to-second time scale, and make possible formal statistical comparisons of burst suppression at different times. Significance. The state-space approach suggests a principled and informative way to analyze burst suppression that can be used to monitor, and eventually to control, the brain states of patients in the operating room and in the intensive care unit.

  6. FRBCAT: The Fast Radio Burst Catalogue

    NASA Astrophysics Data System (ADS)

    Petroff, E.; Barr, E. D.; Jameson, A.; Keane, E. F.; Bailes, M.; Kramer, M.; Morello, V.; Tabbara, D.; van Straten, W.

    2016-09-01

    Here, we present a catalogue of known Fast Radio Burst sources in the form of an online catalogue, FRBCAT. The catalogue includes information about the instrumentation used for the observations for each detected burst, the measured quantities from each observation, and model-dependent quantities derived from observed quantities. To aid in consistent comparisons of burst properties such as width and signal-to-noise ratios, we have re-processed all the bursts for which we have access to the raw data, with software which we make available. The originally derived properties are also listed for comparison. The catalogue is hosted online as a Mysql database which can also be downloaded in tabular or plain text format for off-line use. This database will be maintained for use by the community for studies of the Fast Radio Burst population as it grows.

  7. Backstreaming Electrons Associated With Solar Electron Bursts

    NASA Astrophysics Data System (ADS)

    Skoug, R. M.; Steinberg, J. T.; de Koning, C. A.; Gosling, J. T.; McComas, D. J.

    2007-12-01

    Solar electron bursts are frequently observed in the ACE/SWEPAM suprathermal electron measurements at energies below 1.4 keV. A significant fraction of such events show backscattered electrons, beginning after the burst onset and traveling back towards the Sun along the magnetic field direction. Such backscattered particles imply a scattering mechanism beyond the spacecraft location. Some bursts also show backstreaming conic distributions, implying mirroring at magnetic field enhancements beyond the spacecraft. Here we present a study of these backstreaming particles during solar electron events. We examine the occurrence of backstreaming electrons and their relationship to other burst characteristics such as pitch angle width, duration, and energy range. We also investigate the time delay between burst onset and the appearance of backscattered electrons, including energy and pitch-angle dispersion. We examine the pitch angle distribution and energy dependence of backstreaming electrons, and consider possible origins of these electron distributions and their relationship to solar wind structure beyond the spacecraft.

  8. Ginga Gamma-Ray Burst Line Occurrence

    NASA Technical Reports Server (NTRS)

    Band, David

    1998-01-01

    The purpose of this project is the statistical evaluation of the occurrence of spectral lines in the gamma-ray burst spectra detected by the Ginga burst detector, and the comparison of the Ginga results to the BATSE observations. Two significant line features were detected in the Ginga bursts, but thus far none have been detected in the bursts BATSE detected. These line features may indicate the presence of strong magnetic fields in bursts, and therefore are important physical diagnostics of the conditions in the plasma which radiates the observed gamma-rays. The issue is whether there is a discrepancy between the Ginga and BATSE results; the potential discrepancy must be evaluated statistically. Even if BATSE line detections are announced, the statistical methodology we have developed can be used to estimate the rate at which different types of spectral features occur.

  9. Gamma ray bursts: a 1983 overview

    SciTech Connect

    Cline, T.L.

    1983-10-01

    Gamma ray burst observations are reviewed with mention of new gamma-ray and optical transient measurements and with discussions of the controversial, contradictory and unresolved issues that have recently emerged: burst spectra appear to fluctuate in time as rapidly as they are measured, implying that any one spectrum may be incorrect. Energy spectra can be obligingly fitted to practically any desired shape, implying, in effect, that no objective spectral resolution exists at all. Burst fluxes and temporal quantities, including the total event energy, are characterized very differently with differing instruments, implying that even elementary knowledge of their properties is instrumentally subjective. Finally, the log N-log S determinations are deficient in the weak bursts, while there is no detection of a source direction anisotropy, implying that Ptolemy was right or that burst source distance estimates are basically guesswork. These issues may remain unsolved until vastly improved instruments are flown.

  10. Gamma Ray Bursts: a 1983 Overview

    NASA Technical Reports Server (NTRS)

    Cline, T. L.

    1983-01-01

    Gamma ray burst observations are reviewed with mention of new gamma-ray and optical transient measurements and with discussions of the controversial, contradictory and unresolved issues that have recently emerged: burst spectra appear to fluctuate in time as rapidly as they are measured, implying that any one spectrum may be incorrect; energy spectra can be obligingly fitted to practically any desired shape, implying, in effect, that no objective spectral resolution exists at all; burst fluxes and temporal quantities, including the total event energy, are characterized very differently with differing instruments, implying that even elementary knowledge of their properties is instrumentally subjective; finally, the log N-log S determinations are deficient in the weak bursts, while there is no detection of a source direction anisotropy, implying that Ptolemy was right or that burst source distance estimates are basically guesswork. These issues may remain unsolved until vastly improved instruments are flown.

  11. Microsecond flares in gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Schaefer, Bradley E.; Cohen, Justin; Teegarden, Bonnard J.; Cline, Thomas L.; Fishman, Gerald J.; Meegan, Charles A.; Wilson, Robert B.; Paciesas, William S.; Pendleton, Geoffrey N.; Matteson, James L.

    1993-01-01

    It has been suggested that gamma-ray burst light curves may consist of many superposed flares with a duration shorter than 30/microsec. If true, the implications for the interpretation of burst data are enormous. With the launch of the Compton Gamma-Ray Observatory, four predictions of Mitrofanov's (1989) suggestion can be tested. Our results which contradict this suggestion are (1) the photon arrival times are not correlated between independent detectors, (2) the spectral hardness and intensity does not depend on the detector area, (3) the bursts seen by detectors which measure photon positions do not see microsecond flares, and (4) burst positions deduced from detectors with different projected areas are close to the positions deduced from time-of-flight differences between separated spacecraft. We conclude, therefore, that gamma-ray bursts are not composed of microsecond flares.

  12. Spatiotemporal chaos from bursting dynamics

    SciTech Connect

    Berenstein, Igal; De Decker, Yannick

    2015-08-14

    In this paper, we study the emergence of spatiotemporal chaos from mixed-mode oscillations, by using an extended Oregonator model. We show that bursting dynamics consisting of fast/slow mixed mode oscillations along a single attractor can lead to spatiotemporal chaotic dynamics, although the spatially homogeneous solution is itself non-chaotic. This behavior is observed far from the Hopf bifurcation and takes the form of a spatiotemporal intermittency where the system locally alternates between the fast and the slow phases of the mixed mode oscillations. We expect this form of spatiotemporal chaos to be generic for models in which one or several slow variables are coupled to activator-inhibitor type of oscillators.

  13. Modulation of mitochondrial protein phosphorylation by soluble adenylyl cyclase ameliorates cytochrome oxidase defects

    PubMed Central

    Acin-Perez, Rebeca; Salazar, Eric; Brosel, Sonja; Yang, Hua; Schon, Eric A; Manfredi, Giovanni

    2009-01-01

    Phosphorylation of respiratory chain components has emerged as a mode of regulation of mitochondrial energy metabolism, but its mechanisms are still largely unexplored. A recently discovered intramitochondrial signalling pathway links CO2 generated by the Krebs cycle with the respiratory chain, through the action of a mitochondrial soluble adenylyl cyclase (mt-sAC). Cytochrome oxidase (COX), whose deficiency causes a number of fatal metabolic disorders, is a key mitochondrial enzyme activated by mt-sAC. We have now discovered that the mt-sAC pathway modulates mitochondrial biogenesis in a reactive oxygen species dependent manner, in cultured cells and in animals with COX deficiency. We show that upregulation of mt-sAC normalizes reactive oxygen species production and mitochondrial biogenesis, thereby restoring mitochondrial function. This is the first example of manipulation of a mitochondrial signalling pathway to achieve a direct positive modulation of COX, with clear implications for the development of novel approaches to treat mitochondrial diseases. PMID:20049744

  14. Observing a Burst with Sunglasses

    NASA Astrophysics Data System (ADS)

    2003-11-01

    Unique Five-Week VLT Study of the Polarisation of a Gamma-Ray Burst Afterglow "Gamma-ray bursts (GRBs)" are certainly amongst the most dramatic events known in astrophysics. These short flashes of energetic gamma-rays, first detected in the late 1960's by military satellites, last from less than one second to several minutes. GRBs have been found to be situated at extremely large ("cosmological") distances. The energy released in a few seconds during such an event is larger than that of the Sun during its entire lifetime of more than 10,000 million years. The GRBs are indeed the most powerful events since the Big Bang known in the Universe, cf. ESO PR 08/99 and ESO PR 20/00. During the past years circumstantial evidence has mounted that GRBs signal the collapse of extremely massive stars, the so-called hypernovae. This was finally demonstrated some months ago when astronomers, using the FORS instrument on ESO's Very Large Telescope (VLT), documented in unprecedented detail the changes in the spectrum of the light source ("the optical afterglow") of the gamma-ray burst GRB 030329 (cf. ESO PR 16/03). A conclusive and direct link between cosmological gamma-ray bursts and explosions of very massive stars was provided on this occasion. Gamma-Ray Burst GRB 030329 was discovered on March 29, 2003 by NASA's High Energy Transient Explorer spacecraft. Follow-up observations with the UVES spectrograph at the 8.2-m VLT KUEYEN telescope at the Paranal Observatory (Chile) showed the burst to have a redshift of 0.1685 [1]. This corresponds to a distance of about 2,650 million light-years, making GRB 030329 the second-nearest long-duration GRB ever detected. The proximity of GRB 030329 resulted in very bright afterglow emission, permitting the most extensive follow-up observations of any afterglow to date. A team of astronomers [2] led by Jochen Greiner of the Max-Planck-Institut für extraterrestrische Physik (Germany) decided to make use of this unique opportunity to study the

  15. Living with Respiratory Failure

    MedlinePlus

    ... smoking. Emotional Issues and Support Living with respiratory failure may cause fear, anxiety, depression, and stress. Talk about how you feel with your health care team. Talking to a professional counselor also can ... to living with respiratory failure. You can see how other people who have ...

  16. Respiratory Care Therapist.

    ERIC Educational Resources Information Center

    Ohio State Univ., Columbus. Center on Education and Training for Employment.

    This document, which is designed for use in developing a tech prep competency profile for the occupation of respiratory care therapist, lists technical competencies and competency builders for 18 units pertinent to the health technologies cluster in general as well as those specific to the occupation of respiratory care therapist. The following…

  17. Purification of the Alpha Glycerophosphate Oxidase From Trypanosomes.

    DTIC Science & Technology

    1992-08-01

    is the purifica- tion of the glycerphosphate oxidase from the terminal oxidase in bloodstream trypanosomes. African trypanosomiasis remains one of the...oxidase from the terminal oxidase in bloodstream trypanosomes. African trypanosomiasis remains one of the major diseases in the world today, affecting...interest as a possible target for drug chemotherapy . At present only suramin and organic arsenicals remain as the mainstay of chemotherapy , despite their

  18. Regulation of cytochrome c oxidase by adenylic nucleotides. Is oxidative phosphorylation feedback regulated by its end-products?

    PubMed

    Beauvoit, B; Rigoulet, M

    2001-01-01

    Cytochrome c oxidase, which catalyzes an irreversible step of the respiratory chain, is one of the rate-controlling steps of oxidative phosphorylation on isolated mitochondria. The rate of electron transfer through the complex is primarily controlled by the associated thermodynamic forces, i.e., the span in redox potential between oxygen and cytochrome c and the protonmotive force. However, the electron flux also depends on the various kinetic effectors, including adenylic nucleotides. Although the number of binding sites for ATP and ADP on cytochrome oxidase is still a matter of debate, experiments performed on the solubilized and reconstituted enzyme provide strong functional evidence that the mammalian cytochrome c oxidase binds adenylic nucleotides on both sides of the inner membrane. These effects include modification in cytochrome c affinity, allosteric inhibition and changes in proton pumping efficiency. Immunological studies have pointed out the role of subunit IV and that of an ATP-binding protein, subunit VIa, in these kinetic regulations. In yeast, the role of the nuclear-encoded subunits in assembly and regulation of the cytochrome c oxidase has been further substantiated by using gene-disruption analysis. Using a subunit VIa-null mutant, the consequences of the ATP regulation on oxidative phosphorylation have been further investigated on isolated mitochondria. Taken together, the data demonstrate that there are multiple regulating sites for ATP on the yeast cytochrome oxidase with respect to the location (matrix versus cytosolic side), kinetic effect (activation versus inhibition) and consequence on the flow-force relationships. The question is therefore raised as to the physiological meaning of such feedback regulation of the respiratory chain by ATP in the control and regulation of cellular energy metabolism.

  19. Transcriptional burst frequency and burst size are equally modulated across the human genome

    PubMed Central

    Dar, Roy D.; Razooky, Brandon S.; Singh, Abhyudai; Trimeloni, Thomas V.; McCollum, James M.; Cox, Chris D.; Simpson, Michael L.; Weinberger, Leor S.

    2012-01-01

    Gene expression occurs either as an episodic process, characterized by pulsatile bursts, or as a constitutive process, characterized by a Poisson-like accumulation of gene products. It is not clear which mode of gene expression (constitutive versus bursty) predominates across a genome or how transcriptional dynamics are influenced by genomic position and promoter sequence. Here, we use time-lapse fluorescence microscopy to analyze 8,000 individual human genomic loci and find that at virtually all loci, episodic bursting—as opposed to constitutive expression—is the predominant mode of expression. Quantitative analysis of the expression dynamics at these 8,000 loci indicates that both the frequency and size of the transcriptional bursts varies equally across the human genome, independent of promoter sequence. Strikingly, weaker expression loci modulate burst frequency to increase activity, whereas stronger expression loci modulate burst size to increase activity. Transcriptional activators such as trichostatin A (TSA) and tumor necrosis factor α (TNF) only modulate burst size and frequency along a constrained trend line governed by the promoter. In summary, transcriptional bursting dominates across the human genome, both burst frequency and burst size vary by chromosomal location, and transcriptional activators alter burst frequency and burst size, depending on the expression level of the locus. PMID:23064634

  20. The Case of the Disappearing Spindle Burst

    PubMed Central

    Tiriac, Alexandre; Blumberg, Mark S.

    2016-01-01

    Sleep spindles are brief cortical oscillations at 10–15 Hz that occur predominantly during non-REM (quiet) sleep in adult mammals and are thought to contribute to learning and memory. Spindle bursts are phenomenologically similar to sleep spindles, but they occur predominantly in early infancy and are triggered by peripheral sensory activity (e.g., by retinal waves); accordingly, spindle bursts are thought to organize neural networks in the developing brain and establish functional links with the sensory periphery. Whereas the spontaneous retinal waves that trigger spindle bursts in visual cortex are a transient feature of early development, the myoclonic twitches that drive spindle bursts in sensorimotor cortex persist into adulthood. Moreover, twitches—and their associated spindle bursts—occur exclusively during REM (active) sleep. Curiously, despite the persistence of twitching into adulthood, twitch-related spindle bursts have not been reported in adult sensorimotor cortex. This raises the question of whether such spindle burst activity does not occur in adulthood or, alternatively, occurs but has yet to be discovered. If twitch-related spindle bursts do occur in adults, they could contribute to the calibration, maintenance, and repair of sensorimotor systems. PMID:27119028

  1. Spectral evolution of gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Band, D.; Matteson, J.; Ford, L.; Schaefer, B.; Teegarden, B.; Cline, T.; Paciesas, W.; Pendleton, G.; Fishman, G.; Meegan, C.

    1992-01-01

    BATSE's Spectral Detectors provide a series of high resolution spectra over the duration of a gamma-ray burst; fits to these spectra show the evolution of the continuum as the burst progresses. The burst continuum can usually be fit by the spectral form AE sup alpha exp(-E/kT) from around 25 keV to more than 3 MeV, with varying trends in the value and evolution of the spectral parameters. As a result of limited statistics for E greater than 1 - 2 MeV in the individual spectra, a high energy power law is not required. Only long duration strong bursts can be studied by fitting a series of spectra, and therefore our conclusions concern only this class of burst. The bursts we analyzed tend to be characterized by a hard-to-soft trend both for individual intensity spikes and for the burst as a whole: the hardness leads the count rate in spectra which resolve the temporal variations, while the hardness of successive spikes decreases. We also summarize the performance of the Spectral Detectors and the development of analysis tools to date.

  2. Observational properties of decameter type IV bursts

    NASA Astrophysics Data System (ADS)

    Melnik, Valentin; Brazhenko, Anatoly; Rucker, Helmut; Konovalenko, Alexander; Briand, Carine; Dorovskyy, Vladimir; Zarka, Philippe; Frantzusenko, Anatoly; Panchenko, Michael; Poedts, Stefan; Zaqarashvili, Teimuraz; Shergelashvili, Bidzina

    2013-04-01

    Oscillations of decameter type IV bursts were registered during observations of solar radio emission by UTR-2, URAN-2 and NDA in 2011-2012. Large majority of these bursts were accompanied by coronal mass ejections (CMEs), which were observed by SOHO and STEREO in the visible light. Only in some cases decameter type IV bursts were not associated with CMEs. The largest periods of oscillations P were some tens of minutes. There were some modes of long periods of oscillations simultaneously. Periods of oscillations in flux and in polarization profiles were close. Detailed properties of oscillations at different frequencies were analyzed on the example of two type IV bursts. One of them was observed on April 7, 2011 when a CME happened. Another one (August 1, 2011) was registered without any CME. The 7 April type IV burst had two periods in the frames 75-85 and 35-85 minutes. Interesting feature of these oscillations is decreasing periods with time. The observed decreasing rates dP/dt equaled 0.03-0.07. Concerning type IV burst observed on August 1, 2011 the period of its oscillations increases from 17 min. at 30 MHz to 44 min. at 10 MHz. Connection of type IV burst oscillations with oscillations of magnetic arches and CMEs at corresponding altitudes are discussed. The work is fulfilled in the frame of FP7 project "SOLSPANET".

  3. Activation of group I metabotropic glutamate receptors enhances persistent sodium current and rhythmic bursting in main olfactory bulb external tufted cells

    PubMed Central

    Ennis, Matthew

    2013-01-01

    Rhythmically bursting olfactory bulb external tufted (ET) cells are thought to play a key role in synchronizing glomerular network activity to respiratory-driven sensory input. Whereas spontaneous bursting in these cells is intrinsically generated by interplay of several voltage-dependent currents, bursting strength and frequency can be modified by local intrinsic and centrifugal synaptic input. Activation of metabotropic glutamate receptors (mGluRs) engages a calcium-dependent cation current (ICAN) that increases rhythmic bursting, but mGluRs may also modulate intrinsic mechanisms involved in bursting. Here, we used patch-clamp electrophysiology in rat olfactory bulb slices to investigate whether mGluRs modulate two key intrinsic currents involved in ET cell burst initiation: persistent sodium (INaP) and hyperpolarization-activated cation (Ih) currents. Using a BAPTA-based internal solution to block ICAN, we found that the mGluR1/5 agonist DHPG enhanced INaP but did not alter Ih. INaP enhancement consisted of increased current at membrane potentials between −60 and −50 mV and a hyperpolarizing shift in activation threshold. Both effects would be predicted to shorten the interburst interval. In agreement, DHPG modestly depolarized (∼3.5 mV) ET cells and increased burst frequency without effect on other major burst parameters. This increase was inversely proportional to the basal burst rate such that slower ET cells exhibited the largest increases. This may enable ET cells with slow intrinsic burst rates to pace with faster sniff rates. Taken with other findings, these results indicate that multiple neurotransmitter mechanisms are engaged to fine-tune rhythmic ET cell bursting to context- and state-dependent changes in sniffing frequency. PMID:24225539

  4. Development report for dual-burst disks

    SciTech Connect

    Fusco, A.M.

    1996-11-01

    Burst disks, commonly used in pressure relief applications, were studied as single-use valves. A dual-burst disk design was chosen for primary investigation for systems involving separation of gases of two significantly different pressures. The two disks are used to seal either end of a piston cavity that has a different cross-sectional area on each side. Different piston surface areas are used to maintain hydrostatic equilibrium, P{sub 1}A{sub 1} = P{sub 2}A{sub 2}. The single-use valve functions when the downstream pressure is reduced to approximately atmospheric pressure, creating a pressure differential that causes the burst disks to fail. Several parameters were studied to determine the optimum design of the burst disk. These parameters include thickness, diameter, area/pressure ratio, scoring, and disk geometry. The disk material was limited to 304L stainless steel. Factors that were considered essential to the optimization of the design were robustness, manufacturability, and burst pressure variability. The thicknesses of the disks that were studied range from 0.003 in. to 0.010 in. A model for predicting burst pressures of the burst disks was derived. The model combines membrane stress theory with force/displacement data to predict the burst pressure of various designs to within {+-}10%. This model results from studies that characterize the behavior of individual small and large disks. Welding techniques used to join the dual-disk assembly are discussed. Laser welds are used to join and seal the disks to the bulkhead. These welds were optimized for repeatability and robustness. Resistance upset welding is suggested for joining the dual-disk assembly to the pressure vessel body. Resistance upset weld parameters were developed for this particular design so as to minimize the side effects on the burst-disk performance and to provide high-quality welds.

  5. The First Mammalian Aldehyde Oxidase Crystal Structure

    PubMed Central

    Coelho, Catarina; Mahro, Martin; Trincão, José; Carvalho, Alexandra T. P.; Ramos, Maria João; Terao, Mineko; Garattini, Enrico; Leimkühler, Silke; Romão, Maria João

    2012-01-01

    Aldehyde oxidases (AOXs) are homodimeric proteins belonging to the xanthine oxidase family of molybdenum-containing enzymes. Each 150-kDa monomer contains a FAD redox cofactor, two spectroscopically distinct [2Fe-2S] clusters, and a molybdenum cofactor located within the protein active site. AOXs are characterized by broad range substrate specificity, oxidizing different aldehydes and aromatic N-heterocycles. Despite increasing recognition of its role in the metabolism of drugs and xenobiotics, the physiological function of the protein is still largely unknown. We have crystallized and solved the crystal structure of mouse liver aldehyde oxidase 3 to 2.9 Å. This is the first mammalian AOX whose structure has been solved. The structure provides important insights into the protein active center and further evidence on the catalytic differences characterizing AOX and xanthine oxidoreductase. The mouse liver aldehyde oxidase 3 three-dimensional structure combined with kinetic, mutagenesis data, molecular docking, and molecular dynamics studies make a decisive contribution to understand the molecular basis of its rather broad substrate specificity. PMID:23019336

  6. An oxidase road to platelet adhesion.

    PubMed

    Krause, Diane S

    2016-03-17

    Platelet adhesion to collagen via collagen receptors is an important part of thrombosis. In this issue of Blood, Matsuura et al identify collagen receptors as previously unrecognized targets of the extracellular enzyme lysyl oxidase (LOX), the level of which is increased in myeloproliferative neoplasms (MPNs) and other conditions associated with pathological thromboses.

  7. Polyphenol oxidase activity in annual forage clovers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Polyphenol oxidase (PPO)-mediated phenol reactions in red clover (Trifolium pratense L.) bind forage protein and reduce proteolysis, producing beneficial effects on forage protein degradability, silage fermentation, and soil-N cycling. We evaluated PPO activity in seven previously untested annual c...

  8. A colorimetric assay for cytokinin oxidase.

    PubMed

    Libreros-Minotta, C A; Tipton, P A

    1995-11-01

    A simple and rapid colorimetric assay for cytokinin oxidase is described. The assay is based on the formation of a Schiff base between the enzymatic reaction product 3-methyl-2-butenal and p-aminophenol. The assay is effective in the submicromolar concentration range and can be used in crude plant extracts as well as in more highly purified preparations.

  9. Exploiting algal NADPH oxidase for biophotovoltaic energy.

    PubMed

    Anderson, Alexander; Laohavisit, Anuphon; Blaby, Ian K; Bombelli, Paolo; Howe, Christopher J; Merchant, Sabeeha S; Davies, Julia M; Smith, Alison G

    2016-01-01

    Photosynthetic microbes exhibit light-dependent electron export across the cell membrane, which can generate electricity in biological photovoltaic (BPV) devices. How electrons are exported remains to be determined; the identification of mechanisms would help selection or generation of photosynthetic microbes capable of enhanced electrical output. We show that plasma membrane NADPH oxidase activity is a significant component of light-dependent generation of electricity by the unicellular green alga Chlamydomonas reinhardtii. NADPH oxidases export electrons across the plasma membrane to form superoxide anion from oxygen. The C. reinhardtii mutant lacking the NADPH oxidase encoded by RBO1 is impaired in both extracellular superoxide anion production and current generation in a BPV device. Complementation with the wild-type gene restores both capacities, demonstrating the role of the enzyme in electron export. Monitoring light-dependent extracellular superoxide production with a colorimetric assay is shown to be an effective way of screening for electrogenic potential of candidate algal strains. The results show that algal NADPH oxidases are important for superoxide anion production and open avenues for optimizing the biological component of these devices.

  10. Oxidative stress in rats fed a high-fat high-sucrose diet and preventive effect of polyphenols: Involvement of mitochondrial and NAD(P)H oxidase systems.

    PubMed

    Feillet-Coudray, C; Sutra, T; Fouret, G; Ramos, J; Wrutniak-Cabello, C; Cabello, G; Cristol, J P; Coudray, C

    2009-03-01

    Mitochondrial and NADPH oxidase systems and oxidative stress were investigated in 12 week high-fat high-sucrose (HFHS) diet-fed rats. A protective effect of wine polyphenol (PP) extract was also examined. In liver, maximal activities of CII and CII+III mitochondrial complexes were decreased but NADPH oxidase expression (p22(phox) and p47(phox)) and NADPH oxidase-dependent superoxide anion production were not modified, whereas oxidative stress (lipid and protein oxidation products and antioxidant systems) was increased with HFHS diet. In muscle, anion superoxide production was slightly increased while mitochondrial complex activities and lipid and protein oxidation products were not modified with HFHS diet. In heart, NADPH oxidase expression and superoxide anion production were increased, and maximal activity of mitochondrial respiratory chain complexes or oxidative stress parameters were not modified. Wine polyphenol extract had an inhibiting effect on liver oxidative stress and on heart NADPH oxidase expression and superoxide anion production, and on induction of hepatic steatosis with HFHS diet. Induction of mitochondrial dysfunction could be a primary event in the development of oxidative stress in liver, while in skeletal muscle and in heart the NADPH oxidase system seems to be mainly involved in oxidative stress. Wine polyphenol extract was shown to partially prevent oxidative stress in liver and heart tissues and to nearly completely prevent steatosis development in liver.

  11. Burst Oscillations: Watching Neutron Stars Spin

    NASA Technical Reports Server (NTRS)

    Strohmayer, Tod

    2010-01-01

    It is now almost 15 years since the first detection of rotationally modulated emission from X-ray bursting neutron stars, "burst oscillations," This phenomenon enables us to see neutron stars spin, as the X-ray burst flux asymmetrically lights up the surface. It has enabled a new way to probe the neutron star spin frequency distribution, as well as to elucidate the multidimensional nature of nuclear burning on neutron stars. I will review our current observational understanding of the phenomenon, with an eye toward highlighting some of the interesting remaining puzzles, of which there is no shortage.

  12. Eddy current technique for predicting burst pressure

    DOEpatents

    Petri, Mark C.; Kupperman, David S.; Morman, James A.; Reifman, Jaques; Wei, Thomas Y. C.

    2003-01-01

    A signal processing technique which correlates eddy current inspection data from a tube having a critical tubing defect with a range of predicted burst pressures for the tube is provided. The method can directly correlate the raw eddy current inspection data representing the critical tubing defect with the range of burst pressures using a regression technique, preferably an artificial neural network. Alternatively, the technique deconvolves the raw eddy current inspection data into a set of undistorted signals, each of which represents a separate defect of the tube. The undistorted defect signal which represents the critical tubing defect is related to a range of burst pressures utilizing a regression technique.

  13. The terminal quinol oxidase of the hyperthermophilic archaeon Acidianus ambivalens exhibits a novel subunit structure and gene organization.

    PubMed Central

    Purschke, W G; Schmidt, C L; Petersen, A; Schäfer, G

    1997-01-01

    A terminal quinol oxidase has been isolated from the plasma membrane of the crenarchaeon Acidianus ambivalens (DSM 3772) (formerly Desulfurolobus ambivalens), cloned, and sequenced. The detergent-solubilized complex oxidizes caldariella quinol at high rates and is completely inhibited by cyanide and by quinolone analogs, potent inhibitors of quinol oxidases. It is composed of at least five different subunits of 64.9, 38, 20.4, 18.8, and 7.2 kDa; their genes are located in two different operons. doxB, the gene for subunit I, is located together with doxC and two additional small open reading frames (doxE and doxF) in an operon with a complex transcription pattern. Two other genes of the oxidase complex (doxD and doxA) are located in a different operon and are cotranscribed into a common 1.2-kb mRNA. Both operons exist in duplicate on the genome of A. ambivalens. Only subunit I exhibits clear homology to other members of the superfamily of respiratory heme-copper oxidases; however, it reveals 14 transmembrane helices. In contrast, the composition of the accessory proteins is highly unusual; none is homologous to any known accessory protein of cytochrome oxidases, nor do homologs exist in the databases. DoxA is classified as a subunit II equivalent only by analogy of molecular size and hydrophobicity pattern to corresponding polypeptides of other oxidases. Multiple alignments and phylogenetic analysis of the heme-bearing subunit I (DoxB) locate this oxidase at the bottom of the phylogenetic tree, in the branch of heme-copper oxidases recently suggested to be incapable of superstoichiometric proton pumping. This finding is corroborated by lack of the essential amino acid residues delineating the putative H+-pumping channel. It is therefore concluded that A. ambivalens copes with its strongly acidic environment simply by an extreme turnover of its terminal oxidase, generating a proton gradient only by chemical charge separation. PMID:9023221

  14. Structure–function characterization reveals new catalytic diversity in the galactose oxidase and glyoxal oxidase family

    PubMed Central

    Yin, DeLu (Tyler); Urresti, Saioa; Lafond, Mickael; Johnston, Esther M.; Derikvand, Fatemeh; Ciano, Luisa; Berrin, Jean-Guy; Henrissat, Bernard; Walton, Paul H.; Davies, Gideon J.; Brumer, Harry

    2015-01-01

    Alcohol oxidases, including carbohydrate oxidases, have a long history of research that has generated fundamental biological understanding and biotechnological applications. Despite a long history of study, the galactose 6-oxidase/glyoxal oxidase family of mononuclear copper-radical oxidases, Auxiliary Activity Family 5 (AA5), is currently represented by only very few characterized members. Here we report the recombinant production and detailed structure–function analyses of two homologues from the phytopathogenic fungi Colletotrichum graminicola and C. gloeosporioides, CgrAlcOx and CglAlcOx, respectively, to explore the wider biocatalytic potential in AA5. EPR spectroscopy and crystallographic analysis confirm a common active-site structure vis-à-vis the archetypal galactose 6-oxidase from Fusarium graminearum. Strikingly, however, CgrAlcOx and CglAlcOx are essentially incapable of oxidizing galactose and galactosides, but instead efficiently catalyse the oxidation of diverse aliphatic alcohols. The results highlight the significant potential of prospecting the evolutionary diversity of AA5 to reveal novel enzyme specificities, thereby informing both biology and applications. PMID:26680532

  15. Inhibition of rat fat cell lipolysis by monoamine oxidase and semicarbazide-sensitive amine oxidase substrates.

    PubMed

    Visentin, Virgile; Prévot, Danielle; Marti, Luc; Carpéné, Christian

    2003-04-18

    It has been demonstrated that amine oxidase substrates stimulate glucose transport in cardiomyocytes and adipocytes, promote adipogenesis in pre-adipose cell lines and lower blood glucose in diabetic rats. These insulin-like effects are dependent on amine oxidation by semicarbazide-sensitive amine oxidase or by monoamine oxidase. The present study aimed to investigate whether amine oxidase substrates also exhibit another insulin-like property, the inhibition of lipolysis. We therefore tested the influence of tyramine and benzylamine on lipolytic activity in rat adipocytes. These amines did not modify basal lipolysis but dose-dependently counteracted the stimulation induced by lipolytic agents. The response to 10 nM isoprenaline was totally inhibited by tyramine 1 mM. The blockade produced by inhibition of amine oxidase activity or by 1 mM glutathione suggested that the generation of oxidative species, which occurs during amine oxidation, was involved in tyramine antilipolytic effect. Among the products resulting from amine oxidation, only hydrogen peroxide was antilipolytic in a manner that was potentiated by vanadate, as for tyramine or benzylamine. Antilipolytic responses to tyramine and to insulin were sensitive to wortmannin. These data suggest that inhibition of lipolysis is a novel insulin-like effect of amine oxidase substrates which is mediated by hydrogen peroxide generated during amine oxidation.

  16. Cox1 mutation abrogates need for Cox23 in cytochrome c oxidase biogenesis

    PubMed Central

    Dela Cruz, Richard; Jeong, Mi-Young; Winge, Dennis R.

    2016-01-01

    Cox23 is a known conserved assembly factor for cytochrome c oxidase, although its role in cytochrome c oxidase (CcO) biogenesis remains unresolved. To gain additional insights into its role, we isolated spontaneous suppressors of the respiratory growth defect in cox23∆ yeast cells. We recovered independent colonies that propagated on glycerol/lactate medium for cox23∆ cells at 37°C. We mapped these mutations to the mitochondrial genome and specifically to COX1 yielding an I101F substitution. The I101F Cox1 allele is a gain-of-function mutation enabling yeast to respire in the absence of Cox23. CcO subunit steady-state levels were restored with the I101F Cox1 suppressor mutation and oxygen consumption and CcO activity were likewise restored. Cells harboring the mitochondrial genome encoding I101F Cox1 were used to delete genes for other CcO assembly factors to test the specificity of the Cox1 mutation as a suppressor of cox23∆ cells. The Cox1 mutant allele fails to support respiratory growth in yeast lacking Cox17, Cox19, Coa1, Coa2, Cox14 or Shy1, demonstrating its specific suppressor activity for cox23∆ cells.

  17. A self-adapting approach for the detection of bursts and network bursts in neuronal cultures.

    PubMed

    Pasquale, Valentina; Martinoia, Sergio; Chiappalone, Michela

    2010-08-01

    Dissociated networks of neurons typically exhibit bursting behavior, whose features are strongly influenced by the age of the culture, by chemical/electrical stimulation or by environmental conditions. To help the experimenter in identifying the changes possibly induced by specific protocols, we developed a self-adapting method for detecting both bursts and network bursts from electrophysiological activity recorded by means of micro-electrode arrays. The algorithm is based on the computation of the logarithmic inter-spike interval histogram and automatically detects the best threshold to distinguish between inter- and intra-burst inter-spike intervals for each recording channel of the array. An analogous procedure is followed for the detection of network bursts, looking for sequences of closely spaced single-channel bursts. We tested our algorithm on recordings of spontaneous as well as chemically stimulated activity, comparing its performance to other methods available in the literature.

  18. Coronatine Inhibits Stomatal Closure through Guard Cell-Specific Inhibition of NADPH Oxidase-Dependent ROS Production

    PubMed Central

    Toum, Laila; Torres, Pablo S.; Gallego, Susana M.; Benavídes, María P.; Vojnov, Adrián A.; Gudesblat, Gustavo E.

    2016-01-01

    Microbes trigger stomatal closure through microbe-associated molecular patterns (MAMPs). The bacterial pathogen Pseudomonas syringae pv. tomato (Pst) synthesizes the polyketide toxin coronatine, which inhibits stomatal closure by MAMPs and by the hormone abscisic acid (ABA). The mechanism by which coronatine, a jasmonic acid-isoleucine analog, achieves this effect is not completely clear. Reactive oxygen species (ROS) are essential second messengers in stomatal immunity, therefore we investigated the possible effect of coronatine on their production. We found that coronatine inhibits NADPH oxidase-dependent ROS production induced by ABA, and by the flagellin-derived peptide flg22. This toxin also inhibited NADPH oxidase-dependent stomatal closure induced by darkness, however, it failed to prevent stomatal closure by exogenously applied H2O2 or by salicylic acid, which induces ROS production through peroxidases. Contrary to what was observed on stomata, coronatine did not affect the oxidative burst induced by flg22 in leaf disks. Additionally, we observed that in NADPH oxidase mutants atrbohd and atrbohd/f, as well as in guard cell ABA responsive but flg22 insensitive mutants mpk3, mpk6, npr1-3, and lecrk-VI.2-1, the inhibition of ABA stomatal responses by both coronatine and the NADPH oxidase inhibitor diphenylene iodonium was markedly reduced. Interestingly, coronatine still impaired ABA-induced ROS synthesis in mpk3, mpk6, npr1-3, and lecrk-VI.2-1, suggesting a possible feedback regulation of ROS on other guard cell ABA signaling elements in these mutants. Altogether our results show that inhibition of NADPH oxidase-dependent ROS synthesis in guard cells plays an important role during endophytic colonization by Pst through stomata. PMID:28018388

  19. Other Community Respiratory Viruses.

    PubMed

    Wunderink, Richard G

    2017-03-01

    Polymerase chain reaction-based diagnosis has become the standard for viral pneumonia and other respiratory tract infections. Expansion of respiratory viral panels (RVPs) outside of influenza and, possibly, respiratory syncytial virus has led to the ability to diagnose viral infections for which no approved specific antiviral treatment exists. Careful clinical evaluation of the patient with a positive RVP is, therefore, critical given the limited repertoire of treatments. Generic treatments with intravenous immunoglobulin, ribavirin, and interferons may benefit select severe viral pneumonia patients, whereas cidofovir has activity for severe adenoviral pneumonia.

  20. Respiratory medicine of reptiles.

    PubMed

    Schumacher, Juergen

    2011-05-01

    Noninfectious and infectious causes have been implicated in the development of respiratory tract disease in reptiles. Treatment modalities in reptiles have to account for species differences in response to therapeutic agents as well as interpretation of diagnostic findings. Data on effective drugs and dosages for the treatment of respiratory diseases are often lacking in reptiles. Recently, advances have been made on the application of advanced imaging modalities, especially computed tomography for the diagnosis and treatment monitoring of reptiles. This article describes common infectious and noninfectious causes of respiratory disease in reptiles, including diagnostic and therapeutic regimen.

  1. Bursting the Taylor cone bubble

    NASA Astrophysics Data System (ADS)

    Pan, Zhao; Truscott, Tadd

    2014-11-01

    A soap bubble fixed on a surface and placed in an electric field will take on the shape of a cone rather than constant curvature (dome) when the electrical field is not present. The phenomenon was introduced by J. Zeleny (1917) and studied extensively by C.T. Wilson & G.I. Taylor (1925). We revisit the Taylor cone problem by studying the deformation and bursting of soap bubbles in a point charge electric field. A single bubble takes on the shape of a cone in the electric field and a high-speed camera equipped with a micro-lens is used to observe the unsteady dynamics at the tip. Rupture occurs as a very small piece of the tip is torn away from the bubble toward the point charge. Based on experiments, a theoretical model is developed that predicts when rupture should occur. This study may help in the design of foam-removal techniques in engineering and provide a better understanding of an electrified air-liquid interface.

  2. Gamma-Ray Burst Progenitors

    NASA Astrophysics Data System (ADS)

    Levan, Andrew; Crowther, Paul; de Grijs, Richard; Langer, Norbert; Xu, Dong; Yoon, Sung-Chul

    2016-12-01

    We review our current understanding of the progenitors of both long and short duration gamma-ray bursts (GRBs). Constraints can be derived from multiple directions, and we use three distinct strands; (i) direct observations of GRBs and their host galaxies, (ii) parameters derived from modelling, both via population synthesis and direct numerical simulation and (iii) our understanding of plausible analog progenitor systems observed in the local Universe. From these joint constraints, we describe the likely routes that can drive massive stars to the creation of long GRBs, and our best estimates of the scenarios that can create compact object binaries which will ultimately form short GRBs, as well as the associated rates of both long and short GRBs. We further discuss how different the progenitors may be in the case of black hole engine or millisecond-magnetar models for the production of GRBs, and how central engines may provide a unifying theme between many classes of extremely luminous transient, from luminous and super-luminous supernovae to long and short GRBs.

  3. Gamma-ray burst cosmology

    NASA Astrophysics Data System (ADS)

    Wang, F. Y.; Dai, Z. G.; Liang, E. W.

    2015-08-01

    Gamma-ray bursts (GRBs) are the most luminous electromagnetic explosions in the Universe, which emit up to 8.8 × 1054 erg isotropic equivalent energy in the hard X-ray band. The high luminosity makes them detectable out to the largest distances yet explored in the Universe. GRBs, as bright beacons in the deep Universe, would be the ideal tool to probe the properties of high-redshift universe: including the cosmic expansion and dark energy, star formation rate, the reionization epoch and the metal enrichment history of the Universe. In this article, we review the luminosity correlations of GRBs, and implications for constraining the cosmological parameters and dark energy. Observations show that the progenitors of long GRBs are massive stars. So it is expected that long GRBs are tracers of star formation rate. We also review the high-redshift star formation rate derived from GRBs, and implications for the cosmic reionization history. The afterglows of GRBs generally have broken power-law spectra, so it is possible to extract intergalactic medium (IGM) absorption features. We also present the capability of high-redshift GRBs to probe the pre-galactic metal enrichment and the first stars.

  4. Overview Animation of Gamma-ray Burst

    NASA Video Gallery

    Gamma-ray bursts are the most luminous explosions in the cosmos. Astronomers think most occur when the core of a massive star runs out of nuclear fuel, collapses under its own weight, and forms a b...

  5. POPULATION SYNTHESIS AND GAMMA RAY BURST PROGENITORS

    SciTech Connect

    C. L. FREYER

    2000-12-11

    Population synthesis studies of binaries are always limited by a myriad of uncertainties from the poorly understood effects of binary mass transfer and common envelope evolution to the many uncertainties that still remain in stellar evolution. But the importance of these uncertainties depends both upon the objects being studied and the questions asked about these objects. Here I review the most critical uncertainties in the population synthesis of gamma-ray burst progenitors. With a better understanding of these uncertainties, binary population synthesis can become a powerful tool in understanding, and constraining, gamma-ray burst models. In turn, as gamma-ray bursts become more important as cosmological probes, binary population synthesis of gamma-ray burst progenitors becomes an important tool in cosmology.

  6. Expected Performance of the GLAST Burst Monitor

    NASA Technical Reports Server (NTRS)

    Meegan, Charles; Fishman, Gerald; Kouveliotou, Chryssa; Wilson-Hodge, Colleen; Paciesas, William; Preece, Robert; Briggs, Michael; Bhat, Narayana; Connaughton, Valerie; Greiner, Jochen; vonKienlin, Andreas; Diehl, Roland; Steinle, Helmut; Bissaldi, Elisabetta; Kippen, R. Marc

    2007-01-01

    The GLAST Burst Monitor (GBM) will enhance LAT observations of GRBs by extending the spectral coverage from the LAT threshold down to approx. 8 kev, and will provide a trigger for re-orienting the spacecraft to observe delayed emission from selected bursts outside the LAT field of view. GBM consists of twelve NaI scintillation detectors operating in the 8 kev to 1 MeV energy range and two BGO scintillation detectors operating in the 150 keV to 30 MeV energy range. Detector resolution, effective area, and angular response have been determined by calibrations. Analyses indicate that the on-board burst threshold will be approx. 0.7 photon/cm2/s and the on-board burst localization accuracy will typically be better than 8 degrees.

  7. Impulsive solar X-ray bursts

    NASA Technical Reports Server (NTRS)

    Crannell, C. J.; Frost, K. J.; Maetzler, C.; Ohki, K.; Saba, J. L.

    1977-01-01

    A set of 22 simple, impulsive solar flares, identified in the OSO-5 hard X-ray data, were analyzed together with coincident microwave and meterwave radio observations. The rise times and fall times of the X-ray bursts are found to be highly correlated and effectively equal, strongly suggesting a flare energizing mechanism that is reversible. The good time resolution available for these observations reveals that the microwave emission is influenced by an additional process, evident in the tendency of the microwave emission to peak later and decay more slowly than the symmetric X-ray bursts. Meterwave emission is observed in coincidence with the 5 events which show the strongest time correlation between the X-ray and microwave burst structure. This meterwave emission is characterized by U-burst radiation, indicating confinement of the flare source.

  8. The Gamma-Ray Burst Next Door

    NASA Technical Reports Server (NTRS)

    Wanjek, Christopher

    2003-01-01

    I hesitate to spawn a thousand bad sci-fi flicks, but here it goes: Scientists now say that some gamma-ray bursts, the most powerful explosions in the universe, originate in nearby galaxy clusters. If one were to occur nearby, it could wipe out life on Earth. Fortunately, the chances of mass extinction are slimmer than the Chicago Cubs meeting the Boston Red Sox in the World Series (. . . and the Red Sox winning). But a new analysis of over 1400 archived gamma-ray bursts reveals that about 100 bursts originated within 325 million light-years of Earth, and not billions of light-years away as previously thought. If so, there's no reason why a burst couldn't go off in our galaxy.

  9. NASA's Swift Sees 'Dual Personality' Burst

    NASA Video Gallery

    These animations illustrate two wildly different explanations for GRB 101225A, better known as the "Christmas burst." First, a solitary neutron star in our own galaxy shreds and accretes an approac...

  10. CMEs and frequency cutoff of solar bursts

    NASA Astrophysics Data System (ADS)

    Stanislavsky, Al.; Konovalenko, Al.; Koval, Ar.; Volvach, Y.; Zarka, P.

    2016-05-01

    Radio observations of solar bursts with high-frequency cutoff by the radio telescope UTR-2 (near Kharkiv, Ukraine) at 8-33 MHz on 17-19 August 2012 are presented. Such cutoff may be attributed to the emergence of the burst sources behind limb of the Sun with respect to an observer on the Earth. The events are strongly associated with solar eruptions occurred in a new active region. Ray tracing simulations show that the CMEs play a constructive role for the behind-limb bursts to be detected in ground-based observations. Likely, due to tunnel-like cavities with low density in CMEs, the radio emission of behind-limb solar bursts can be directed towards the Earth.

  11. GLAST Burst Monitor Trigger Classification Algorithm

    NASA Technical Reports Server (NTRS)

    Perrin, D. J.; Sidman, E. D.; Meegan, C. A.; Briggs, M. S.; Connaughton, V.

    2004-01-01

    The Gamma Ray Large Area Space Telescope (GLAST), currently set for launch in the first quarter of 2007, will consist of two instruments, the GLAST Burst Monitor (GBM) and the Large Area Telescope (LAT). One of the goals of the GBM is to identify and locate gamma-ray bursts using on-board software. The GLAST observatory can then be re-oriented to allow observations by the LAT. A Bayesian analysis will be used to distinguish gamma-ray bursts from other triggering events, such as solar flares, magnetospheric particle precipitation, soft gamma repeaters (SGRs), and Cygnus X-1 flaring. The trigger parameters used in the analysis are the burst celestial coordinates, angle from the Earth's horizon, spectral hardness, and the spacecraft geomagnetic latitude. The algorithm will be described and the results of testing will be presented.

  12. Transverse Bursts in Inclined Layer Convection: Experiment

    NASA Astrophysics Data System (ADS)

    Daniels, Karen; Wiener, Richard; Bodenschatz, Eberhard

    2002-03-01

    We report experimental results on inclined layer convection in a fluid of Prandtl number σ ≈ 1. A codimension-two point divides regions of buoyancy-driven convection (longitudinal rolls) at lower angles from shear-driven convection (transverse rolls) at higher angles (Daniels et al. PRL 84: 5320, 2000). In the region of buoyancy-driven convection, near the codimension-two point, we observe longitudinal rolls with intermittent, localized, subharmonic transverse bursts. The patterns are spatiotemporally chaotic. With increasing temperature difference the bursts increase in duration and number. We examine the details of the bursting process (e.g. the energy of longitudinal, transverse, and mixed modes) and compare our results to bursting processes in other systems. This work is supported by the National Science Foundation under grant DMR-0072077 and the IGERT program in nonlinear systems, grant DGE-9870631.

  13. Optimal Codes for the Burst Erasure Channel

    NASA Technical Reports Server (NTRS)

    Hamkins, Jon

    2010-01-01

    Deep space communications over noisy channels lead to certain packets that are not decodable. These packets leave gaps, or bursts of erasures, in the data stream. Burst erasure correcting codes overcome this problem. These are forward erasure correcting codes that allow one to recover the missing gaps of data. Much of the recent work on this topic concentrated on Low-Density Parity-Check (LDPC) codes. These are more complicated to encode and decode than Single Parity Check (SPC) codes or Reed-Solomon (RS) codes, and so far have not been able to achieve the theoretical limit for burst erasure protection. A block interleaved maximum distance separable (MDS) code (e.g., an SPC or RS code) offers near-optimal burst erasure protection, in the sense that no other scheme of equal total transmission length and code rate could improve the guaranteed correctible burst erasure length by more than one symbol. The optimality does not depend on the length of the code, i.e., a short MDS code block interleaved to a given length would perform as well as a longer MDS code interleaved to the same overall length. As a result, this approach offers lower decoding complexity with better burst erasure protection compared to other recent designs for the burst erasure channel (e.g., LDPC codes). A limitation of the design is its lack of robustness to channels that have impairments other than burst erasures (e.g., additive white Gaussian noise), making its application best suited for correcting data erasures in layers above the physical layer. The efficiency of a burst erasure code is the length of its burst erasure correction capability divided by the theoretical upper limit on this length. The inefficiency is one minus the efficiency. The illustration compares the inefficiency of interleaved RS codes to Quasi-Cyclic (QC) LDPC codes, Euclidean Geometry (EG) LDPC codes, extended Irregular Repeat Accumulate (eIRA) codes, array codes, and random LDPC codes previously proposed for burst erasure

  14. A Non-Triggered Burst Supplement to the BATSE Gamma-Ray Burst Catalogs

    NASA Technical Reports Server (NTRS)

    Kommers, J.; Lewin, W. H.; Kouveliotou, C.; vanParadijs, J.; Pendleton, G. N.; Meegan, C. A.; Fishman, G. J.

    1998-01-01

    The Burst and Transient Source Experiment (BATSE) on the Compton Gamma Ray Observatory detects gamma-ray bursts (GRBs) with a real-time burst detection (or "trigger") system running onboard the spacecraft. Under some circumstances, however, a GRB may not activate the onboard burst trigger. For example, the burst may be too faint to exceed the onboard detection threshold, or it may occur while the onboard burst trigger is disabled for technical reasons. This paper is a catalog of such "non-triggered" GRBs that were detected in a search of the archival continuous data from BATSE. It lists 873 non-triggered bursts that were recorded between 1991 December 9.0 and 1997 December 17.0. For each burst, the catalog gives an estimated source direction, duration, peak flux, and fluence. Similar data are presented for 50 additional bursts of unknown origin that were detected in the 25-50 keV range; these events may represent the low-energy "tail" of the GRB spectral distribution. This catalog increases the number of GRBs detected with BATSE by 48% during the time period covered by the search.

  15. QoS-guaranteed burst transmission for VoIP service over optical burst switching networks

    NASA Astrophysics Data System (ADS)

    Tachibana, Takuji; Kasahara, Shoji

    2007-08-01

    We propose a burst transmission method that guarantees the voice over Internet protocol (VoIP) service. The proposed method consists of three techniques: round-robin burst assembly with slotted scheduling, priority control with void filling, and hop-based preemption. Each technique is utilized so that the burst loss probability and the burst transmission delay satisfy VoIP quality of service (QoS). We evaluate by simulation the performance of the proposed method in NSFNET with 14 nodes. Numerical examples show that our proposed method is effective for guaranteeing the VoIP QoS while accommodating a large number of VoIP users.

  16. Progress Report: Pressure Vessel Burst Test Study

    DTIC Science & Technology

    1994-08-01

    report is provided on a program developed to study through test and analysis, the characteristics of blast waves and fragmentation generated by ruptured ...vessels were composite overwrapped pressure vessels ( COPV ) and were cut with a shaped charge (no groove) around its center. The burst location on the...and the shaped charge cut area (shown with dotted lines). BURST INITIATION Longitudinal stress in the circumferential grooves (for developing axial

  17. Localizing the Fast Radio Burst 121102

    NASA Astrophysics Data System (ADS)

    Chatterjee, Shami; Wharton, Robert; Law, Casey J.; Hessels, Jason; Burke-Spolaor, Sarah; Bower, Geoffrey C.; Abruzzo, Matthew W.; Bassa, Cees; Butler, Bryan J.; Cordes, James M.; Paul, Demorest; Kaspi, Victoria M.; McLaughlin, Maura; Ransom, Scott M.; Scholz, Paul; Seymour, Andrew; Spitler, Laura; Tendulkar, Shriharsh P.; PALFA Survey Team; VLA+AO FRB121102 Simultaneous Campaign Team; EVN FRB121102 Campaign Team

    2017-01-01

    The precise localization of a fast radio burst and the identification of its host counterpart would allow constraints on their distances and energetics, and enable us to discriminate between various origin scenarios, from the local and mundane to the cosmological and exotic. Here we report on the results of an ongoing localization campaign on the repeating fast radio burst source, FRB 121102, with the VLA, Arecibo, and other telescopes.

  18. Gamma-Ray Burst Class Properties

    NASA Technical Reports Server (NTRS)

    Hakkila, Jon; Haglin, David J.; Pendleton, Geoffrey N.; Mallozzi, Robert S.; Meegan, Charles A.; Roiger, Richard J.

    2000-01-01

    Guided by the supervised pattern recognition algorithm C4.5 developed by Quinlan in 1986, we examine the three gamma-ray burst classes identified by Mukherjee et al. in 1998. C4.5 provides strong statistical support for this classification. However, with C4.5 and our knowledge of the Burst and Transient Source Experiment (BATSE) instrument, we demonstrate that class 3 (intermediate fluence, intermediate duration, soft) does not have to be a distinct source population: statistical/systematic errors in measuring burst attributes combined with the well-known hardness/intensity correlation can cause low peak flux class 1 (high fluence, long, intermediate hardness) bursts to take on class 3 characteristics naturally. Based on our hypothesis that the third class is not a distinct one, we provide rules so that future events can be placed in either class 1 or class 2 (low fluence, short, hard). We find that the two classes are relatively distinct on the basis of Band's work in 1993 on spectral parameters alpha, beta, and E (sub peak) alone. Although this does not indicate a better basis for classification, it does suggest that different physical conditions exist for class 1 and class 2 bursts. In the process of studying burst class characteristics, we identify a new bias affecting burst fluence and duration measurements. Using a simple model of how burst duration can be underestimated, we show how this fluence duration bias can affect BATSE measurements and demonstrate the type of effect it can have on the BATSE fluence versus peak flux diagram.

  19. Variable Protostellar Accretion with Episodic Bursts

    NASA Astrophysics Data System (ADS)

    Vorobyov, Eduard I.; Basu, Shantanu

    2015-06-01

    We present the latest development of the disk gravitational instability and fragmentation model, originally introduced by us to explain episodic accretion bursts in the early stages of star formation. Using our numerical hydrodynamics model with improved disk thermal balance and star-disk interaction, we computed the evolution of protostellar disks formed from the gravitational collapse of prestellar cores. In agreement with our previous studies, we find that cores of higher initial mass and angular momentum produce disks that are more favorable to gravitational instability and fragmentation, while a higher background irradiation and magnetic fields moderate the disk tendency to fragment. The protostellar accretion in our models is time-variable, thanks to the nonlinear interaction between different spiral modes in the gravitationally unstable disk, and can undergo episodic bursts when fragments migrate onto the star owing to the gravitational interaction with other fragments or spiral arms. Most bursts occur in the partly embedded Class I phase, with a smaller fraction taking place in the deeply embedded Class 0 phase and a few possible bursts in the optically visible Class II phase. The average burst duration and mean luminosity are found to be in good agreement with those inferred from observations of FUors. The model predicts the existence of two types of bursts: the isolated ones, showing well-defined luminosity peaks separated with prolonged periods (˜ {{10}4} yr) of quiescent accretion, and clustered ones, demonstrating several bursts occurring one after another during just a few hundred years. Finally, we estimate that 40%-70% of the star-forming cores can display bursts after forming a star-disk system.

  20. Search for absorption edges in superexpansion bursts

    NASA Astrophysics Data System (ADS)

    in't Zand, Jean

    2013-09-01

    Our goal is to measure with the LETGS a series of bright type-I X-ray bursts with strong photospheric radius expansion ('superexpansion') to search for absorption edges due to the ashes of nuclear burning. We request a quick TOO, to be triggered by ISS-MAXI and Swift-BAT, with a total exposure time of 100 ks to obtain the detection of about 10 bursts.

  1. GAMCIT: A gamma ray burst detector

    NASA Technical Reports Server (NTRS)

    Surka, Derek M.; Grunsfeld, John M.; Warneke, Brett A.

    1992-01-01

    The origin of celestial gamma ray bursts remains one of the great mysteries of modern astrophysics. The GAMCIT Get-Away-Special payload is designed to provide new and unique data in the search for the sources of gamma ray bursts. GAMCIT consists of three gamma ray detectors, an optical CCD camera, and an intelligent electronics system. This paper describes the major components of the system, including the electronics and structural designs.

  2. Supernovae and gamma-ray bursts connection

    SciTech Connect

    Valle, Massimo Della

    2015-12-17

    I’ll review the status of the Supernova/Gamma-Ray Burst connection. Several pieces of evidence suggest that long duration Gamma-ray Bursts are associated with bright SNe-Ic. However recent works suggest that GRBs might be produced in tight binary systems composed of a massive carbon-oxygen cores and a neutron star companion. Current estimates of the SN and GRB rates yield a ratio GRB/SNe-Ibc in the range ∼ 0.4% − 3%.

  3. Further observations of the burst source MXB 1728-34

    NASA Technical Reports Server (NTRS)

    Hoffman, J. A.; Lewin, W. H. G.; Doty, J.

    1977-01-01

    MXB 1728-34 has been observed by the SAS 3 observatory on eight occasions. It was bursting 95-100 per cent of the time, with burst intervals from 4 to 8 hr. The burst intervals were not correlated with the burst intensities. Seven relatively hard bursts occurring in July 1976 were all observed at energies up to about 30 keV. Following each of these bursts, enhanced X-ray emission was observed for several minutes, with a much softer spectrum than that of the bursts themselves. No periodic pulsations were observed from the associated steady source.

  4. Mitochondrial cytochrome c oxidase: mechanism of action and role in regulating oxidative phosphorylation.

    PubMed

    Wilson, David F; Vinogradov, Sergei A

    2014-12-15

    Mitochondrial oxidative phosphorylation has a central role in eukaryotic metabolism, providing the energy (ATP) required for survival. Regulation of this important pathway is, however, still not understood, largely due to limitations in the ability to measure the essential metabolites, including oxygen (pO2, oxygen pressure), ADP, and AMP. In addition, neither the mechanism of oxygen reduction by mitochondrial cytochrome c oxidase nor how its rate is controlled is understood, although this enzyme determines the rate of oxygen consumption and thereby the rate of ATP synthesis. Cytochrome c oxidase is responsible for reduction of molecular oxygen to water using reducing equivalents donated by cytochrome c and for site 3 energy coupling in oxidative phosphorylation. A mechanism-based model of the cytochrome c oxidase reaction is presented in which transfer of reducing equivalents from the lower- to the higher-potential region of the coupling site occurs against an opposing energy barrier, Q. The steady-state rate equation is fitted to data for the dependence of mitochondrial respiratory rate on cytochrome c reduction, oxygen pressure (pO2), and [ATP]/[ADP][Pi] at pH 6.5 to 8.35 (where Pi is inorganic phosphate). The fit of the rate expression to the experimental data is very good for all experimental conditions. Levels of the intermediates in oxygen reduction in the oxidase reaction site have been calculated. An intermediate in the reaction, tentatively identified as peroxide, bridged between the iron and copper atoms of the reaction site has a central role in coupling mitochondrial respiration to the [ATP]/[ADP][Pi].

  5. Physics of Gamma Ray Burst Sources

    NASA Technical Reports Server (NTRS)

    Meszaros, Peter

    2004-01-01

    During this grant period, the physics of gamma-ray bursts was investigated. A number of new results have emerged. The importance of pair formation in high compactness burst spectra may help explain x-ray flashes; a universal jet shape is a likely explanation for the distribution of jet break times; gravitational waves may be copiously produced both in short bursts from compact mergers and in long bursts arising from collapsars; x-ray iron lines are likely to be due to interaction with the stellar atmosphere of the progenitor; prompt optical flashes from reverse shocks will give diagnostics on the Lorentz factor and the environment; GeV and TeV emission from bursts may be expected in the external shock; etc. The group working with the PI included postdocs Dr. Bing Zhang (now assistant professor at University of Nevada); Dr. Shiho Kobayashi; graduate student Lijun Gou; collaborators Drs. Tim Kallman and Martin Rees. Meszaros shared with Rees and Dr. Bohan Paczynsky the AAS Rossi Prize in 2000 for their work on the theory of gamma ray bursts. The refereed publications and conference proceedings resulting from this research are summarized below. The PI gave a number of invited talks at major conferences, also listed.

  6. Voyager observations of Jovian millisecond radio bursts

    NASA Technical Reports Server (NTRS)

    Alexander, J. K.; Desch, M. D.

    1984-01-01

    Voyager Planetary Radio Astronomy data collected over 30-day intervals centered on the two close encounters with Jupiter were utilized to study the characteristics of millisecond-duration radio bursts (s-bursts) at frequencies between 5 and 15 MHz. In this frequency range, s-bursts are found to occur almost independently of Central Meridian Longitude and to depend entirely on the phase of Io with respect to the observer's planetocentric line of sight. Individual bursts typically cover a total frequency range of about 1.5 to 3 MHz, and they are usually strongly circularly polarized. Most bursts in a particular s-burst storm will exhibit the same polarization sense (either right-hand or left-hand), and there is some evidence for a systematic pattern in which one polarizations sense is preferred over the other as a function of Io phase and Central Meridian Longitude. These data are all suggestive of a radio source that is located along the instantaneous Io flux tube and that extends over a linear dimension of 5000 km along the field lines in both the northern and southern Hemispheres.

  7. Phase analysis method for burst onset prediction

    NASA Astrophysics Data System (ADS)

    Stellino, Flavio; Mazzoni, Alberto; Storace, Marco

    2017-02-01

    The response of bursting neurons to fluctuating inputs is usually hard to predict, due to their strong nonlinearity. For the same reason, decoding the injected stimulus from the activity of a bursting neuron is generally difficult. In this paper we propose a method describing (for neuron models) a mechanism of phase coding relating the burst onsets with the phase profile of the input current. This relation suggests that burst onset may provide a way for postsynaptic neurons to track the input phase. Moreover, we define a method of phase decoding to solve the inverse problem and estimate the likelihood of burst onset given the input state. Both methods are presented here in a unified framework, describing a complete coding-decoding procedure. This procedure is tested by using different neuron models, stimulated with different inputs (stochastic, sinusoidal, up, and down states). The results obtained show the efficacy and broad range of application of the proposed methods. Possible applications range from the study of sensory information processing, in which phase-of-firing codes are known to play a crucial role, to clinical applications such as deep brain stimulation, helping to design stimuli in order to trigger or prevent neural bursting.

  8. The microbiota of the respiratory tract: gatekeeper to respiratory health.

    PubMed

    Man, Wing Ho; de Steenhuijsen Piters, Wouter A A; Bogaert, Debby

    2017-03-20

    The respiratory tract is a complex organ system that is responsible for the exchange of oxygen and carbon dioxide. The human respiratory tract spans from the nostrils to the lung alveoli and is inhabited by niche-specific communities of bacteria. The microbiota of the respiratory tract probably acts as a gatekeeper that provides resistance to colonization by respiratory pathogens. The respiratory microbiota might also be involved in the maturation and maintenance of homeostasis of respiratory physiology and immunity. The ecological and environmental factors that direct the development of microbial communities in the respiratory tract and how these communities affect respiratory health are the focus of current research. Concurrently, the functions of the microbiome of the upper and lower respiratory tract in the physiology of the human host are being studied in detail. In this Review, we will discuss the epidemiological, biological and functional evidence that support the physiological role of the respiratory microbiota in the maintenance of human health.

  9. Respiratory Syncytial Virus

    MedlinePlus

    ... respiratory syncytial virus (RSV) using indirect immunofluorescence technique. Biology & Genetics For more than 50 years, NIAID’s commitment ... Nucleotide Polymorphism Phylogenetics & Ontology Proteomics & Protein Analysis Systems Biology Data Portals Software Applications BCBB Mobyle Interface Designer ( ...

  10. Respiratory Syncytial Virus Infections

    MedlinePlus

    Respiratory syncytial virus (RSV) causes mild, cold-like symptoms in adults and older healthy children. It can cause serious problems in ... tests can tell if your child has the virus. There is no specific treatment. You should give ...

  11. Respiratory muscle plasticity.

    PubMed

    Rowley, Katharine L; Mantilla, Carlos B; Sieck, Gary C

    2005-07-28

    Plasticity of respiratory muscles must be considered in the context of their unique physiological demands. The continuous rhythmic activation of respiratory muscles makes them among the most active in the body. Respiratory muscles, especially the diaphragm, are non-weight-bearing, and thus, in contrast to limb muscles, are not exposed to gravitational effects. Perturbations in normal activation and load known to induce plasticity in limb muscles may not cause similar adaptations in respiratory muscles. In this review, we explore the structural and functional properties of the diaphragm muscle and their response to alterations in load and activity. Overall, relatively modest changes in diaphragm structural and functional properties occur in response to perturbations in load or activity. However, disruptions in the normal influence of phrenic innervation by frank denervation, tetrodotoxin nerve block and spinal hemisection, induce profound changes in the diaphragm, indicating the substantial trophic influence of phrenic motoneurons on diaphragm muscle.

  12. Noninvasive respiratory monitoring

    SciTech Connect

    Nochomovitz, M.L.; Cherniack, N.S.

    1986-01-01

    This book contains 10 selections. Some of the titles are: Transcutaneous Monitoring of Respiratory Gases; Computed Tomography of the Chest; Measurement and Monitoring of Exhaled Carbon Dioxide; Oximetry; and Ultrasonic Evaluation of the Chest Wall and Pleura.

  13. What Causes Respiratory Failure?

    MedlinePlus

    ... Conditions Causing Respiratory Failure Figure A shows the location of the lungs, airways, diaphragm, rib cage, pulmonary arteries, brain, and spinal cord ... STATEMENT FOIA NO FEAR ACT OIG CONTACT US ...

  14. Molecular mechanisms of generation for nitric oxide and reactive oxygen species, and role of the radical burst in plant immunity.

    PubMed

    Yoshioka, Hirofumi; Asai, Shuta; Yoshioka, Miki; Kobayashi, Michie

    2009-10-31

    Rapid production of nitric oxide (NO) and reactive oxygen species (ROS) has been implicated in the regulation of innate immunity in plants. A potato calcium-dependent protein kinase (StCDPK5) activates an NADPH oxidase StRBOHA to D by direct phosphorylation of N-terminal regions, and heterologous expression of StCDPK5 and StRBOHs in Nicotiana benthamiana results in oxidative burst. The transgenic potato plants that carry a constitutively active StCDPK5 driven by a pathogen-inducible promoter of the potato showed high resistance to late blight pathogen Phytophthora infestans accompanied by HR-like cell death and H(2)O(2) accumulation in the attacked cells. In contrast, these plants showed high susceptibility to early blight necrotrophic pathogen Alternaria solani, suggesting that oxidative burst confers high resistance to biotrophic pathogen, but high susceptibility to necrotrophic pathogen. NO and ROS synergistically function in defense responses. Two MAPK cascades, MEK2-SIPK and cytokinesis-related MEK1-NTF6, are involved in the induction of NbRBOHB gene in N. benthamiana. On the other hand, NO burst is regulated by the MEK2-SIPK cascade. Conditional activation of SIPK in potato plants induces oxidative and NO bursts, and confers resistance to both biotrophic and necrotrophic pathogens, indicating the plants may have obtained during evolution the signaling pathway which regulates both NO and ROS production to adapt to wide-spectrum pathogens.

  15. Bd oxidase homologue of photosynthetic purple sulfur bacterium Allochromatium vinosum is co-transcribed with a nitrogen fixation related gene.

    PubMed

    Dincturk, H Benan; Demir, Volkan; Aykanat, Tutku

    2011-02-01

    Purple sulfur bacteria, which are known to be the most ancient among anoxygenic phototrophs, play an important role in the global sulfur cycle. Allochromatium vinosum oxidizes reduced sulfur compounds such as hydrogen sulfide, elemental sulfur and thiosulfide. At low oxygen concentrations, A. vinosum can grow chemotrophically using oxygen as the terminal electron acceptor. Being also a nitrogen fixer, A. vinosum is faced with the paradox of co-existence of aerobic metabolism and nitrogen fixation. Due to growth difficulties, only a few studies have dealt with the aerobic metabolism of the organism and, until now, there has been no information about the genes involved in the respiratory metabolism of purple sulfur bacteria. In this article we show the first terminal oxidase gene for A. vinosum. The presence of a Bd type of quinol oxidase is necessary to protect nitrogenases against the inhibitory effects of oxygen. In this case, a nitrogen fixation related gene is part of the cyd operon and this gene is co-transcribed with cydAB genes. Bd oxidase of A. vinosum may be the earliest form of oxidase where the function of the enzyme is to scavenge the contaminant oxygen during nitrogen fixation. This may be an important clue about the early evolution of oxygenic photosynthesis, perhaps as a protective mechanism for nitrogen fixation.

  16. Polyphenols decreased liver NADPH oxidase activity, increased muscle mitochondrial biogenesis and decreased gastrocnemius age-dependent autophagy in aged rats.

    PubMed

    Laurent, Caroline; Chabi, Beatrice; Fouret, Gilles; Py, Guillaume; Sairafi, Badie; Elong, Cecile; Gaillet, Sylvie; Cristol, Jean Paul; Coudray, Charles; Feillet-Coudray, Christine

    2012-09-01

    This study explored major systems of reactive oxygen species (ROS) production and their consequences on oxidative stress, mitochondriogenesis and muscle metabolism in aged rats, and evaluated the efficiency of 30-day oral supplementation with a moderate dose of a red grape polyphenol extract (RGPE) on these parameters. In the liver of aged rats, NADPH oxidase activity was increased and mitochondrial respiratory chain complex activities were altered, while xanthine oxidase activity remained unchanged. In muscles, only mitochondrial activity was modified with aging. The oral intake of RGPE decreased liver NADPH oxidase activity in the aged rats without affecting global oxidative stress, suggesting that NADPH oxidase was probably not the dominant detrimental source of production of O(2)·(-) in the liver. Interestingly, RGPE supplementation increased mitochondrial biogenesis and improved antioxidant status in the gastrocnemius of aged rats, while it had no significant effect in soleus. RGPE supplementation also decreased age-dependent autophagy in gastrocnemius of aged rats. These results extended existing findings on the beneficial effects of RGPE on mitochondriogenesis and muscle metabolism in aged rats.

  17. Investigation of Factors Affecting Aerobic and Respiratory Growth in the Oxygen-Tolerant Strain Lactobacillus casei N87

    PubMed Central

    Ianniello, Rocco G.; Matera, Attilio; Genovese, Francesco; Parente, Eugenio; Ricciardi, Annamaria

    2016-01-01

    Aerobic and respiratory cultivations provide benefits for some lactic acid bacteria (LAB). Growth, metabolites, enzymatic activities (lactate dehydrogenase; pyruvate and NADH oxidases, NADH peroxidase; catalase), antioxidant capability and stress tolerance of Lactobacillus casei N87 were evaluated in anaerobic, aerobic and respiratory (aerobiosis with heme and menaquinone supplementation) batch cultivations with different dissolved oxygen (DO) concentrations. The expression of pox (pyruvate oxidase) and cydABCD operon (cytochrome bd oxidase complex) was quantified by quantitative Real Time polymerase chain reaction. Respiration increased biomass production compared to anaerobiosis and unsupplemented aerobiosis, and altered the central metabolism rerouting pyruvate away from lactate accumulation. All enzymatic activities, except lactate dehydrogenase, were higher in respiratory cultures, while unsupplemented aerobiosis with 60% of DO promoted H2O2 and free radical accumulation. Respiration improved the survival to oxidative and freeze-drying stresses, while significant numbers of dead, damaged and viable but not cultivable cells were found in unsupplemented aerobic cultures (60% DO). Analysis of gene expression suggested that the activation of aerobic and respiratory pathways occurred during the exponential growth phase, and that O2 and hemin induced, respectively, the transcription of pox and cydABCD genes. Respiratory cultivation might be a natural strategy to improve functional and technological properties of L. casei. PMID:27812097

  18. Phylogenetic trends in respiratory rhythmogenesis: insights from ectothermic vertebrates.

    PubMed

    Kinkead, Richard

    2009-08-31

    Understanding the neural substrate driving breathing has puzzled physiologists for more than a century. The discovery of the pre-Bötzinger complex (preBötC) in newborn rodents as a structure with a unique physiological function in respiratory rhythm generation was an important progress in respiratory neurobiology that stimulated much research. Owing to the extensive literature describing the location, organisation, and function of the preBötC mainly in newborn rodents, this structure has become the point of reference in studies addressing respiratory rhythm generation in other mammals and various classes of vertebrates. This paper reviews recent progress made in non-mammalian vertebrates in our understanding of the location and function of the neural networks driving respiratory activity. As in newborn rodents, data from lampreys, air breathing fish, and amphibians show that the production of eupnea is the result of interactions between multiple (at least two) rhythmogenic networks. These networks are located in anatomically distinct areas and show different functional properties in terms of their ability to produce (or not) bursting activity in the absence of synaptic inputs (e.g. pacemaker neurons) and their sensitivity to specific neuromodulators such as substance P, somatostatin, and opioids. Current data indicate that respiratory rhythmogenesis is a phylogenetically ancient function that was highly conserved throughout evolution and that a comparative approach remains important to derive broader biological principles and a more comprehensive view.

  19. Modeling gamma-ray bursts

    NASA Astrophysics Data System (ADS)

    Maxham, Amanda

    Discovered serendipitously in the late 1960s, gamma-ray bursts (GRBs) are huge explosions of energy that happen at cosmological distances. They provide a grand physical playground to those who study them, from relativistic effects such as beaming, jets, shocks and blastwaves to radiation mechanisms such as synchrotron radiation to galatic and stellar populations and history. Through the Swift and Fermi space telescopes dedicated to observing GRBs over a wide range of energies (from keV to GeV), combined with accurate pinpointing that allows ground based follow-up observations in the optical, infrared and radio, a rich tapestry of GRB observations has emerged. The general picture is of a mysterious central engine (CE) probably composed of a black hole or neutron star that ejects relativistic shells of matter into intense magnetic fields. These shells collide and combine, releasing energy in "internal shocks" accounting for the prompt emission and flaring we see and the "external shock" or plowing of the first blastwave into the ambient surrounding medium has well-explained the afterglow radiation. We have developed a shell model code to address the question of how X-ray flares are produced within the framework of the internal shock model. The shell model creates randomized GRB explosions from a central engine with multiple shells and follows those shells as they collide, merge and spread, producing prompt emission and X-ray flares. We have also included a blastwave model, which can constrain X-ray flares and explain the origin of high energy (GeV) emission seen by the Fermi telescope. Evidence suggests that gamma-ray prompt emission and X-ray flares share a common origin and that at least some flares can only be explained by long-lasting central engine activity. We pay special attention to the time history of central engine activity, internal shocks, and observed flares. We calculate the gamma-ray (Swift/BAT band) and X-ray (Swift/XRT band) lightcurves for arbitrary

  20. [Involvement of hydrogen peroxide in the regulation of coexpression of alternative oxidase and rotenone-insensitive NADH dehydrogenase in tomato leaves and calluses].

    PubMed

    Eprintsev, A T; Mal'tseva, E V; Shatskikh, A S; Popov, V N

    2011-01-01

    The involvement of active oxygen forms in the regulation of the expression of mitochondrial respiratory chain components, which are not related to energy storing, has been in vitro and in vivo studied in Lycopersicum esculentum L. The highest level of transcription of genes encoding alternative oxidase and NADH dehydrogenase has been observed in green tomato leaves. It has been shown that even low H2O2 concentrations activate both aoxlalpha and ndb1 genes, encoding alternative oxidase and external mitochondrial rotenone-insensitive NADH dehydrogenase, respectively. According to our results, in the case of an oxidative stress, alternative oxidase and NADH dehydrogenase are coexpressed in tomato plant tissues, and active oxygen forms serve as the secondary messengers of their coexpression.

  1. Stimulation of Respiratory Motor Output and Ventilation in a Murine Model of Pompe Disease by Ampakines

    PubMed Central

    ElMallah, Mai K.; Pagliardini, Silvia; Turner, Sara M.; Cerreta, Anthony J.; Falk, Darin J.; Byrne, Barry J.; Greer, John J.

    2015-01-01

    Pompe disease results from a mutation in the acid α-glucosidase gene leading to lysosomal glycogen accumulation. Respiratory insufficiency is common, and the current U.S. Food and Drug Administration–approved treatment, enzyme replacement, has limited effectiveness. Ampakines are drugs that enhance α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor responses and can increase respiratory motor drive. Recent work indicates that respiratory motor drive can be blunted in Pompe disease, and thus pharmacologic stimulation of breathing may be beneficial. Using a murine Pompe model with the most severe clinical genotype (the Gaa−/− mouse), our primary objective was to test the hypothesis that ampakines can stimulate respiratory motor output and increase ventilation. Our second objective was to confirm that neuropathology was present in Pompe mouse medullary respiratory control neurons. The impact of ampakine CX717 on breathing was determined via phrenic and hypoglossal nerve recordings in anesthetized mice and whole-body plethysmography in unanesthetized mice. The medulla was examined using standard histological methods coupled with immunochemical markers of respiratory control neurons. Ampakine CX717 robustly increased phrenic and hypoglossal inspiratory bursting and reduced respiratory cycle variability in anesthetized Pompe mice, and it increased inspiratory tidal volume in unanesthetized Pompe mice. CX717 did not significantly alter these variables in wild-type mice. Medullary respiratory neurons showed extensive histopathology in Pompe mice. Ampakines stimulate respiratory neuromotor output and ventilation in Pompe mice, and therefore they have potential as an adjunctive therapy in Pompe disease. PMID:25569118

  2. Stimulation of Respiratory Motor Output and Ventilation in a Murine Model of Pompe Disease by Ampakines.

    PubMed

    ElMallah, Mai K; Pagliardini, Silvia; Turner, Sara M; Cerreta, Anthony J; Falk, Darin J; Byrne, Barry J; Greer, John J; Fuller, David D

    2015-09-01

    Pompe disease results from a mutation in the acid α-glucosidase gene leading to lysosomal glycogen accumulation. Respiratory insufficiency is common, and the current U.S. Food and Drug Administration-approved treatment, enzyme replacement, has limited effectiveness. Ampakines are drugs that enhance α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor responses and can increase respiratory motor drive. Recent work indicates that respiratory motor drive can be blunted in Pompe disease, and thus pharmacologic stimulation of breathing may be beneficial. Using a murine Pompe model with the most severe clinical genotype (the Gaa(-/-) mouse), our primary objective was to test the hypothesis that ampakines can stimulate respiratory motor output and increase ventilation. Our second objective was to confirm that neuropathology was present in Pompe mouse medullary respiratory control neurons. The impact of ampakine CX717 on breathing was determined via phrenic and hypoglossal nerve recordings in anesthetized mice and whole-body plethysmography in unanesthetized mice. The medulla was examined using standard histological methods coupled with immunochemical markers of respiratory control neurons. Ampakine CX717 robustly increased phrenic and hypoglossal inspiratory bursting and reduced respiratory cycle variability in anesthetized Pompe mice, and it increased inspiratory tidal volume in unanesthetized Pompe mice. CX717 did not significantly alter these variables in wild-type mice. Medullary respiratory neurons showed extensive histopathology in Pompe mice. Ampakines stimulate respiratory neuromotor output and ventilation in Pompe mice, and therefore they have potential as an adjunctive therapy in Pompe disease.

  3. Natural Compounds as Modulators of NADPH Oxidases

    PubMed Central

    2013-01-01

    Reactive oxygen species (ROS) are cellular signals generated ubiquitously by all mammalian cells, but their relative unbalance triggers also diseases through intracellular damage to DNA, RNA, proteins, and lipids. NADPH oxidases (NOX) are the only known enzyme family with the sole function to produce ROS. The NOX physiological functions concern host defence, cellular signaling, regulation of gene expression, and cell differentiation. On the other hand, increased NOX activity contributes to a wide range of pathological processes, including cardiovascular diseases, neurodegeneration, organ failure, and cancer. Therefore targeting these enzymatic ROS sources by natural compounds, without affecting the physiological redox state, may be an important tool. This review summarizes the current state of knowledge of the role of NOX enzymes in physiology and pathology and provides an overview of the currently available NADPH oxidase inhibitors derived from natural extracts such as polyphenols. PMID:24381714

  4. Lysyl Oxidase and the Tumor Microenvironment

    PubMed Central

    Wang, Tong-Hong; Hsia, Shih-Min; Shieh, Tzong-Ming

    2016-01-01

    The lysyl oxidase (LOX) family of oxidases contains a group of extracellular copper-dependent enzymes that catalyze the cross-linking of collagen and elastin by oxidation, thus maintaining the rigidity and structural stability of the extracellular matrix (ECM). Aberrant expression or activation of LOX alters the cellular microenvironment, leading to many diseases, including atherosclerosis, tissue fibrosis, and cancer. Recently, a number of studies have shown that LOX is overexpressed in most cancers and that it is involved in the regulation of tumor progression and metastasis. In contrast, a few reports have also indicated the tumor-suppressing role of LOX. In this short review, we discuss recent research on the correlations between LOX and cancer. Further, the role of LOX in tumor microenvironment remodeling, tumorigenesis, and metastasis and the underlying mechanisms have also been elucidated. PMID:28036074

  5. The respiratory chains of four strains of the alkaliphilic Bacillus clausii.

    PubMed

    Abbrescia, A; Martino, P L; Panelli, D; Sardanelli, A M; Papa, S; Alifano, P; Palese, L L; Gaballo, A

    2014-01-01

    A comparative analysis of terminal respiratory enzymes has been performed on four strains of Bacillus clausii used for preparation of a European probiotic. These four strains originated most probably from a common ancestor through early selection of stable clones for industrial propagation. They exhibit a low level of intra-specific diversity and a high degree of genomic conservation, making them an attractive model to study the different bioenergetics behaviors of alkaliphilic bacilli. The analysis of the different bioenergetics responses has been carried out revealing striking differences among the strains. Two out of the four strains have shown a functional redundancy of the terminal part of the respiratory chain. The biochemical data correlate with the expression level of the mRNA of cytochrome c oxidase and quinol oxidase genes (heme-copper type). The consequences of these different bioenergetics behaviors are also discussed.

  6. Lysyl oxidase mediates hypoxic control of metastasis.

    PubMed

    Erler, Janine T; Giaccia, Amato J

    2006-11-01

    Hypoxic cancer cells pose a great challenge to the oncologist because they are especially aggressive, metastatic, and resistant to therapy. Recently, we showed that elevation of the extracellular matrix protein lysyl oxidase (LOX) correlates with metastatic disease and is essential for hypoxia-induced metastasis. In an orthotopic rodent model of breast cancer, a small-molecule or antibody inhibitor of LOX abolished metastasis, offering preclinical validation of this enzyme as a therapeutic target.

  7. Ligand interactions with galactose oxidase: mechanistic insights.

    PubMed Central

    Whittaker, M M; Whittaker, J W

    1993-01-01

    Interactions between galactose oxidase and small molecules have been explored using a combination of optical absorption, circular dichroism, and electron paramagnetic resonance (EPR) spectroscopies to detect complex formation and characterize the products. Anions bind directly to the cupric center in both active and inactive galactose oxidase, converting to complexes with optical and EPR spectra that are distinctly different from those of the starting aquo enzyme. Azide binding is coupled to stoichiometric proton uptake by the enzyme, reflecting the generation of a strong base (pKa > 9) in the active site anion adduct. At low temperature, the aquo enzyme converts to a form that exhibits the characteristic optical and EPR spectra of an anion complex, apparently reflecting deprotonation of the coordinated water. Anion binding results in a loss of the optical transition arising from coordinated tyrosine, implying displacement of the axial tyrosine ligand on forming the adduct. Nitric oxide binds to galactose oxidase, forming a specific complex exhibiting an unusual EPR spectrum with all g values below 2. The absence of Cu splitting in this spectrum and the observation that the cupric EPR signal from the active site metal ion is not significantly decreased in the complex suggest a nonmetal interaction site for NO in galactose oxidase. These results have been interpreted in terms of a mechanistic scheme where substrate binding displaces a tyrosinate ligand from the active site cupric ion, generating a base that may serve to deprotonate the coordinated hydroxyl group of the substrate, activating it for oxidation. The protein-NO interactions may probe a nonmetal O2 binding site in this enzyme. PMID:8386015

  8. Imaging Monoamine Oxidase in the Human Brain

    SciTech Connect

    Fowler, J. S.; Volkow, N. D.; Wang, G-J.; Logan, Jean

    1999-11-10

    Positron emission tomography (PET) studies mapping monoamine oxidase in the human brain have been used to measure the turnover rate for MAO B; to determine the minimum effective dose of a new MAO inhibitor drug lazabemide and to document MAO inhibition by cigarette smoke. These studies illustrate the power of PET and radiotracer chemistry to measure normal biochemical processes and to provide information on the effect of drug exposure on specific molecular targets.

  9. Tetrazolium Oxidase Polymorphism in Rainbow Trout

    PubMed Central

    Cederbaum, Stephen D.; Yoshida, Akira

    1972-01-01

    Tetrazolium oxidase from the blood and liver of rainbow trout was found to be genetically polymorphic. The inheritance pattern of the liver enzyme was compatible only with a one locus-two allele hypothesis. The enzymes in the blood while having an electrophoretically identical polymorphism could differ genotypically from that of the liver in a given fish. The significance of these findings to the understanding of the evolution of the salmonid genome is discussed. PMID:4675090

  10. Method and apparatus for coherent burst ranging

    DOEpatents

    Wachter, Eric A.; Fisher, Walter G.

    1998-01-01

    A high resolution ranging method is described utilizing a novel modulated waveform, hereafter referred to as coherent burst modulation. In the coherent burst method, high frequency modulation of an acoustic or electromagnetic transmitter, such as a laser, is performed at a modulation frequency. This modulation frequency is transmitted quasi-continuously in the form of interrupted bursts of radiation. Energy from the transmitter is directed onto a target, interacts with the target, and the returning energy is collected. The encoded burst pattern contained in the collected return signal is detected coherently by a receiver that is tuned so as to be principally sensitive to the modulation frequency. The receiver signal is processed to determine target range using both time-of-flight of the burst envelope and phase shift of the high frequency modulation. This approach effectively decouples the maximum unambiguous range and range resolution relationship of earlier methods, thereby allowing high precision ranging to be conducted at arbitrarily long distances using at least one burst of encoded energy. The use of a receiver tuned to the high frequency modulation contained within the coherent burst vastly improves both sensitivity in the detection of the target return signal and rejection of background interferences, such as ambient acoustic or electromagnetic noise. Simultaneous transmission at several energies (or wavelengths) is possible by encoding each energy with a separate modulation frequency or pattern; electronic demodulation at the receiver allows the return pattern for each energy to be monitored independently. Radial velocity of a target can also be determined by monitoring change in phase shift of the return signal as a function of time.

  11. Method and apparatus for coherent burst ranging

    DOEpatents

    Wachter, E.A.; Fisher, W.G.

    1998-04-28

    A high resolution ranging method is described utilizing a novel modulated waveform, hereafter referred to as coherent burst modulation. In the coherent burst method, high frequency modulation of an acoustic or electromagnetic transmitter, such as a laser, is performed at a modulation frequency. This modulation frequency is transmitted quasi-continuously in the form of interrupted bursts of radiation. Energy from the transmitter is directed onto a target, interacts with the target, and the returning energy is collected. The encoded burst pattern contained in the collected return signal is detected coherently by a receiver that is tuned so as to be principally sensitive to the modulation frequency. The receiver signal is processed to determine target range using both time-of-flight of the burst envelope and phase shift of the high frequency modulation. This approach effectively decouples the maximum unambiguous range and range resolution relationship of earlier methods, thereby allowing high precision ranging to be conducted at arbitrarily long distances using at least one burst of encoded energy. The use of a receiver tuned to the high frequency modulation contained within the coherent burst vastly improves both sensitivity in the detection of the target return signal and rejection of background interferences, such as ambient acoustic or electromagnetic noise. Simultaneous transmission at several energies (or wavelengths) is possible by encoding each energy with a separate modulation frequency or pattern; electronic demodulation at the receiver allows the return pattern for each energy to be monitored independently. Radial velocity of a target can also be determined by monitoring change in phase shift of the return signal as a function of time. 12 figs.

  12. A biomechanical study on burst mechanisms of plant fruit: stress analysis of pericarps before bursting.

    PubMed

    Endo, Yasuhiro; Sakamoto, Jiro; Kashiwano, Yuki; Yokota, Hideo; Nakamura, Sakiko; Kinoshita, Eichiro

    2010-10-01

    Bursting of fruit is a very interesting biomechanical phenomenon because its mechanism is directly related to the plant's reproduction. A plant that produces fruit that bursts powerfully and spreads the seeds widely has the advantage of reproduction without relying on other mechanisms such as transportation of fruit by insects. The structures of many types of fruit have likely been optimized by evolution, although the structure itself appears rather simplistic. Strain energy is stored in each pericarp because of growth deformation, swelling or desiccation just before bursting. Throughout these changes, the mechanical stress of the pericarps is at equilibrium. At the instant of bursting, the stored strain energy is released very rapidly. Quick and wide motion of the pericarps in a certain direction is advantageous for throwing the seed a long distance. The motion and deformation of bursting pericarps depend on their tissue structure and mechanical stress condition just before the burst. We tracked the bursting motion by using a high-speed camera. Then we calculated the pre-burst stress generated in a pericarp of Impatiens by using the finite-element method. The boundary condition obtained by experiments using a high-speed video camera is given, and the stress was calculated using reverse deformation analysis. The stress distribution of the pericarp is effective in causing the pericarp motion to throw the seeds far away.

  13. A Nontriggered Burst Supplement to the BATSE Gamma-Ray Burst Catalogs

    NASA Technical Reports Server (NTRS)

    Kommers, Jefferson M.; Lewin, Walter H. G.; Kouveliotou, Chryssa; vanParadijs, Jan; Pendleton, Geoffrey N.; Meegan, Charles A.; Fishman, Gerald J.

    2001-01-01

    The Burst and Transient Source Experiment (BATSE) on the Compton Gamma Ray Observatory detects gamma-ray bursts (GRBs) with a real-time burst detection (or "trigger") system running onboard the spacecraft. Under some circumstances, however, a GRB may not activate the on-board burst trigger. For example, the burst may be too faint to exceed the on-board detection threshold, or it may occur while the on-board burst trigger is disabled for technical reasons. This paper describes a catalog of 873 "nontriggered" GRBs that were detected in a search of the archival continuous data from BATSE recorded between 1991 December 9.0 and 1997 December 17.0. For each burst, the catalog gives an estimated source direction, duration, peak flux, and fluence. Similar data are presented for 50 additional bursts of unknown origin that were detected in the 25-50 keV range; these events may represent the low-energy "tail" of the GRB spectral distribution. This catalog increases the number of GRBs detected with BATSE by 48% during the time period covered by the search.

  14. Xanthine dehydrogenase to xanthine oxidase conversion in ischemic rat intestine

    SciTech Connect

    McKelvey, T.G.; Engerson, T.D.; Elmore, C.R.; Jones, H.P. )

    1990-02-26

    The ischemic conversion of the NADH-producing xanthine dehydrogenase (XDH) to an oxidase form, that produces both superoxide radical and hydrogen peroxide, has been proposed as an important step in initiating oxygen radical-mediated ischemia-reperfusion injury. It has also been reported that two forms of converted oxidase are produced in ischemic rat liver; a reversible xanthine oxidase produced through sulfhydryl oxidation, that can be reconverted to XDH by incubation with 10mM dithiothreitol (Dtt) at 37{degrees}C, and a Dtt-irreversible oxidase produced via proteolysis. The authors report that increased oxidase in the ischemic rat intestine results from significant increases in both the Dtt-reversible and Dtt-irreversible forms of xanthine oxidase. Total oxidase activity (Irreversible + Dtt-reversible) was 19% of the total enzyme activity (XDH + XO) in control ileum and distal jejunum, increased to 26% after 1 hour of ischemia at 37{degrees}C, and significantly to 36% after 1.5 hours. After 3 hours 73% of the activity was in the oxidase form. Irreversible oxidase comprised 15% of the total activity in control intestine, significantly increased to 25% after 2 hours, and further to 42% after 3 hours. Dtt-reversible oxidase was 3% of the total activity in controls, increased to 13% after 1.5 hours, and significantly to 29% after 2 hours.

  15. Hypoglossal Neuropathology and Respiratory Activity in Pompe Mice

    PubMed Central

    Sandhu, Milapjit S.; Elmallah, Mai K.; Falk, Darin J.; Lane, Michael A.; Reier, Paul J.; Byrne, Barry J.; Fuller, David D.

    2011-01-01

    Pompe disease is a lysosomal storage disorder associated with systemic deficiency of acid α-glucosidase (GAA). Respiratory-related problems in Pompe disease include hypoventilation and upper airway dysfunction. Although these problems have generally been attributed to muscular pathology, recent work has highlighted the potential role of central nervous system (CNS) neuropathology in Pompe motor deficiencies. We used a murine model of Pompe disease to test the hypothesis that systemic GAA deficiency is associated with hypoglossal (XII) motoneuron pathology and altered XII motor output during breathing. Brainstem tissue was harvested from adult Gaa−/− mice and the periodic acid Schiff method was used to examine neuronal glycogen accumulation. Semi-thin (2 μm) plastic sections showed widespread medullary neuropathology with extensive cytoplasmic glycogen accumulation in XII motoneuron soma. We next recorded efferent XII bursting in anesthetized and ventilated Gaa−/− and B6/129 mice both before and after bilateral vagotomy. The coefficient of variation of respiratory cycle duration was greater in Gaa−/− compared to B6/129 mice (p < 0.01). Vagotomy caused a robust increase in XII inspiratory burst amplitude in B6/129 mice (239 ± 44% baseline; p < 0.01) but had little impact on burst amplitude in Gaa−/− mice (130 ± 23% baseline; p > 0.05). We conclude that CNS GAA deficiency results in substantial glycogen accumulation in XII motoneuron cell bodies and altered XII motor output. Therapeutic strategies targeting the CNS may be required to fully correct respiratory-related deficits in Pompe disease. PMID:21747768

  16. Mutations in the Arabidopsis gene IMMUTANS cause a variegated phenotype by inactivating a chloroplast terminal oxidase associated with phytoene desaturation.

    PubMed Central

    Carol, P; Stevenson, D; Bisanz, C; Breitenbach, J; Sandmann, G; Mache, R; Coupland, G; Kuntz, M

    1999-01-01

    The immutans (im) mutant of Arabidopsis shows a variegated phenotype comprising albino and green somatic sectors. We have cloned the IM gene by transposon tagging and show that even stable null alleles give rise to a variegated phenotype. The gene product has amino acid similarity to the mitochondrial alternative oxidase. We show that the IM protein is synthesized as a precursor polypeptide that is imported into chloroplasts and inserted into the thylakoid membrane. The albino sectors of im plants contain reduced levels of carotenoids and increased levels of the carotenoid precursor phytoene. The data presented here are consistent with a role for the IM protein as a cofactor for carotenoid desaturation. The suggested terminal oxidase function of IM appears to be essential to prevent photooxidative damage during early steps of chloroplast formation. We propose a model in which IM function is linked to phytoene desaturation and, possibly, to the respiratory activity of the chloroplast. PMID:9878632

  17. Two NADPH oxidase isoforms are required for sexual reproduction and ascospore germination in the filamentous fungus Podospora anserina.

    PubMed

    Malagnac, Fabienne; Lalucque, Hervé; Lepère, Gersende; Silar, Philippe

    2004-11-01

    NADPH oxidases are enzymes that produce reactive oxygen species (ROS) using electrons derived from intracellular NADPH. In plants and mammals, ROS have been proposed to be second messengers that signal defence responses or cell proliferation. By inactivating PaNox1 and PaNox2, two genes encoding NADPH oxidases, we demonstrate the crucial role of these enzymes in the control of two key steps of the filamentous fungus Podospora anserina life cycle. PaNox1 mutants are impaired in the differentiation of fruiting bodies from their progenitor cells, and the deletion of the PaNox2 gene specifically blocks ascospore germination. Furthermore, we show that PaNox1 likely acts upstream of PaASK1, a MAPKKK previously implicated in stationary phase differentiation and cell degeneration. Using nitro blue tetrazolium (NBT) and diaminobenzidine (DAB) assays, we detect a regulated secretion of both superoxide and peroxide during P. anserina vegetative growth. In addition, two oxidative bursts are shown to occur during fruiting body development and ascospore germination. Analysis of mutants establishes that PaNox1, PaNox2, and PaASK1, as well as a still unknown additional source of ROS, modulate these secretions. Altogether, our data point toward a role for NADPH oxidases in signalling fungal developmental transitions with respect to nutrient availability. These enzymes are conserved in other multicellular eukaryotes, suggesting that early eukaryotes were endowed with a redox network used for signalling purposes.

  18. QKD-Based Secured Burst Integrity Design for Optical Burst Switched Networks

    NASA Astrophysics Data System (ADS)

    Balamurugan, A. M.; Sivasubramanian, A.; Parvathavarthini, B.

    2016-03-01

    The field of optical transmission has undergone numerous advancements and is still being researched mainly due to the fact that optical data transmission can be done at enormous speeds. It is quite evident that people prefer optical communication when it comes to large amount of data involving its transmission. The concept of switching in networks has matured enormously with several researches, architecture to implement and methods starting with Optical circuit switching to Optical Burst Switching. Optical burst switching is regarded as viable solution for switching bursts over networks but has several security vulnerabilities. However, this work exploited the security issues associated with Optical Burst Switching with respect to integrity of burst. This proposed Quantum Key based Secure Hash Algorithm (QKBSHA-512) with enhanced compression function design provides better avalanche effect over the conventional integrity algorithms.

  19. FRB121102: statistics of burst properties compared to the fast radio burst population

    NASA Astrophysics Data System (ADS)

    Seymour, Andrew; Michilli, Daniele; McLaughlin, Maura; Chatterjee, Shami; Hessel, Jason; Spolaor, Sarah; Paul, Demorest; Scholz, Paul; Spitler, Laura; Tendulkar, Shriharsh P.; PALFA Survey Team; VLA+AO FRB121102 Simultaneous Campaign Team; EVN FRB121102 Campaign Team

    2017-01-01

    Fast Radio Bursts (FRBs) are millisecond-long radio events with dispersion measures that exceed that expected from our Galaxy. Therefore the FRB source is anticipated to be extragalactic and highly energetic. Until recently, these were only observed as one-off events. This was until multiple bursts were observed at the Arecibo Observatory from FRB 121102. I will present the most recent burst statistics from FRB 121102's follow-up observations. Understanding the distribution of all burst characteristics can eliminate some of the proposed mechanisms to FRB 121102’s burst events. Not only that, comparing these values to the rest of the FRB population can give insight as to whether FRB 121102 is distinct from the rest of the FRB population.

  20. Herringbone bursts associated with type II solar radio emission

    NASA Technical Reports Server (NTRS)

    Cairns, I. H.; Robinson, R. D.

    1987-01-01

    Detailed observations of the herringbone (HB) fine structure on type II solar radio bursts are presented. Data from the Culgoora radiospectrograph, radiometer and radioheliograph are analyzed. The characteristic spectral profiles, frequency drift rates and exciter velocities, fluxes, source sizes, brightness temperatures, and polarizations of individual HB bursts are determined. Correlations between individual bursts within the characteristic groups of bursts and the properties of the associated type II bursts are examined. These data are compatible with HB bursts being radiation at multiples of the plasma frequency generated by electron streams accelerated by the type II shock. HB bursts are physically distinct phenomena from type II and type III bursts, differing significantly in emission processes and/or source conditions; this conclusion indicates that many of the presently available theoretical ideas for HB bursts are incorrect.

  1. Oscillations During Thermonuclear X-ray Bursts

    NASA Technical Reports Server (NTRS)

    Strohmayer, Tod E.; White, Nicholas E. (Technical Monitor)

    2001-01-01

    High amplitude, nearly coherent X-ray brightness oscillations during thermonuclear X-ray bursts were discovered with the Rossi X-ray Timing Explorer (RXTE) in early 1996. Spectral and timing evidence strongly supports the conclusion that these oscillations are caused by rotational modulation of the burst emission and that they reveal the spin frequency of neutron stars in low mass X-ray binaries, a long sought goal of X-ray astronomy. Studies carried out over the past year have led to the discovery of burst oscillations in four new sources, bringing to ten the number with confirmed burst oscillations. I review the status of our knowledge of these oscillations and indicate how they can be used to probe the physics of neutron stars. For a few burst oscillation sources it has been proposed that the strongest and most ubiquitous frequency is actually the first overtone of the spin frequency and hence that two nearly antipodal hot spots are present on the neutron star. This inference has important implications for both the physics of thermonuclear burning as well as the mass - radius relation for neutron stars, so its confirmation is crucial. I discuss recent attempts to confirm this hypothesis for 4U 1636-53, the source for which a signal at the putative fundamental (290Hz) has, been claimed.

  2. Superfine Structure of Jovian Millisecond Radio Bursts

    NASA Astrophysics Data System (ADS)

    Rucker, H. O.; Litvinenko, G.; Taubenschuss, U.; Leitner, M.; Lecacheux, A.; Konovalenko, A.

    2004-05-01

    Jupiter decameter (DAM) radio emission mainly consists of wide-band radio storms with time scales in seconds (L-bursts) and milliseconds (S-bursts), the latter comprising a series of short pulses with duration of a few to tens of milliseconds, and strongly controlled by the satellite Io. First in-depth analysis of the subpulse structure was made by Carr and Reyes (1999) with the discovery of successive deep envelope modulations, with time resolution better than 30 microseconds, and during these subpulse periods the discovery of phase coherence. Recent observations by means of the newly developed waveform receiver (at present unsurpassed in spectral resolution) and connected to the decameter world-largest radio telescope UTR-2 (Kharkov) yielded waveform measurements of Jovian S-bursts which have been analyzed by the wavelet analysis method. Main outcome of the present investigation is the detection of clear signatures of microsecond modulations, providing evidence of a superfine burst structure with the following parameters: a) instantaneous frequency band of one separated microsecond pulse of 100 to 300 kHz, b) time duration of one separated micropulse of 6 to 15 microseconds, and c) time interval between closest subsequent microsecond pulses of 5 to 25 microseconds. The apparent frequency drift of a millisecond burst evidently results from sequentially decreasing frequencies of subsequent subpulses, each representing an island of phase coherent gyrating electron bunches.

  3. Transverse Bursts in Inclined Layer Convection: Theory

    NASA Astrophysics Data System (ADS)

    Bodenschatz, Eberhard; Brink, Jeandrew; Pesch, Werner

    2002-03-01

    We report theoretical and computational results on thermally driven inclined layer convection. For small Prandtl number fluids, experiments have reported bursting phenomena at both small angles, strong driving and high angles, weak driving (Daniels et al. PRL 84: 5320, 2000). Theoretically, the small angle, strong driving case was described by Clever and Busse (Physics of Fluids 12: 2137, 2000) and was connected to a subharmonic instability. At large angles, close to the codimension-two point, intermittent, localized, transverse subharmonic bursts occur at weak driving. Qualitatively, the bursts draw energy from the roll modes, exhaust them while growing, and die out when they are unable to find a new attractor. We investigate a connection between the small- and large-angle bursts. Using Galerkin methods and direct simulations of the underlying Boussinesq equations, we examine the extent to which they are related to a linear instability of the roll pattern. We address a possible connection to the shear flow turbulent bursts observed in Taylor-Couette flow. In addition, we present a theoretical analysis of the small Prandtl number case, for which the codimension-two point moves to zero angle. This work is supported by a Cornell Graduate Student Fellowship and by the National Science Foundation under grant DMR-0072077.

  4. GRB Catalog: Bursts from Vela to Swift

    NASA Technical Reports Server (NTRS)

    Angelini, L.

    2008-01-01

    Gamma ray burst (GRB) astronomy started when the first event was recorded on July 2, 1967 by Vela 4a and 4b. Since then many missions have flown experiments capable of detecting GRBs. The events collected by these older experiments are mostly available in paper copy, each containing a few ten to a few hundred bursts. No systematic effort in cataloging of these bursts has been available. In some cases the information is unpublished and in others difficult to retrieve. The first major GRB catalog was obtained by GRO with the BATSE experiment. It contains more than 2000 bursts and includes homogeneous information for each of the bursts. With the launch of Swift, the first Gamma-ray/X-ray mission dedicated to the study of GRBs and their afterglows, a wealth of information is collected by the Swift instrument as well as from ground-based telescopes. This talk will describe the efforts to create a comprehensive GRBCAT and its current status and future prospective.

  5. Substrate specificity of guinea pig liver aldehyde oxidase and bovine milk xanthine oxidase for methyl- and nitrobenzaldehydes.

    PubMed

    Veskoukis, Aristidis S; Kouretas, Demetrios; Panoutsopoulos, Georgios I

    2006-01-01

    Both aldehyde oxidase and xanthine oxidase catalyze the oxidation of a wide range of N-heterocycles and aldehydes. These enzymes are important in the oxidation of N-heterocyclic xenobiotics, whereas their role in the oxidation of xenobiotic aldehydes is usually ignored. The present investigation describes the interaction of methyl- and nitrosubstituted benzaldehydes, in the ortho-, meta- and parapositions, with guinea pig liver aldehyde oxidase and bovine milk xanthine oxidase. The kinetic constants showed that most substituted benzaldehydes are excellent substrates of aldehyde oxidase with lower affinities for xanthine oxidase. Low Km values for aldehyde oxidase were observed with most benzaldehydes tested, with 3-nitrobenzaldehyde having the lowest Km value and 3-methylbenzaldehyde being the best substrate in terms of substrate efficiency (Ks). Additionally, low Km values for xanthine oxidase were found with most benzaldehydes tested. However, all benzaldehydes also had low Vmax values, which made them poor substrates of xanthine oxidase. It is therefore possible that aldehyde oxidase may be critical in the oxidation of xenobiotic and endobiotic derived aldehydes and its role in such reactions should not be ignored.

  6. Investigating the role of the physiological isoform switch of cytochrome c oxidase subunits in reversible mitochondrial disease.

    PubMed

    Boczonadi, Veronika; Giunta, Michele; Lane, Maria; Tulinius, Mar; Schara, Ulrike; Horvath, Rita

    2015-06-01

    Reversible infantile respiratory chain deficiency is characterised by spontaneous recovery of mitochondrial myopathy in infants. We studied whether a physiological isoform switch of nuclear cytochrome c oxidase subunits contributes to the age-dependent manifestation and spontaneous recovery in reversible mitochondrial disease. Some nuclear-encoded subunits of cytochrome c oxidase are present as tissue-specific isoforms. Isoforms of subunits COX6A and COX7A expressed in heart and skeletal muscle are different from isoforms expressed in the liver, kidney and brain. Furthermore, in skeletal muscle both the heart and liver isoforms of subunit COX7A have been demonstrated with variable levels, indicating that the tissue-specific expression of nuclear-encoded subunits could provide a basis for the fine-tuning of cytochrome c oxidase activity to the specific metabolic needs of the different tissues. We demonstrate a developmental isoform switch of COX6A and COX7A subunits in human and mouse skeletal muscle. While the liver type isoforms are more present soon after birth, the heart/muscle isoforms gradually increase around 3 months of age in infants, 4 weeks of age in mice, and these isoforms persist in muscle throughout life. Our data in follow-up biopsies of patients with reversible infantile respiratory chain deficiency indicate that the physiological isoform switch does not contribute to the clinical manifestation and to the spontaneous recovery of this disease. However, understanding developmental changes of the different cytochrome c oxidase isoforms may have implications for other mitochondrial diseases. This article is part of a Directed Issue entitled: Energy Metabolism Disorders and Therapies.

  7. Steps towards a mechanistic understanding of respiratory temperature responses.

    PubMed

    Kruse, Jörg; Rennenberg, Heinz; Adams, Mark A

    2011-02-01

    Temperature crucially affects the speed of metabolic processes in poikilotherm organisms, including plants. The instantaneous temperature responses of O(2)-reduction and CO(2)-release can be approximated by Arrhenius kinetics, even though respiratory gas exchange of plants is the net effect of many constituent biochemical processes. Nonetheless, the classical Arrhenius equation must be modified to account for a dynamic response to measurement temperatures. We show that this dynamic response is readily explained by combining Arrhenius and Michaelis-Menten kinetics, as part of a fresh appraisal of metabolic interpretations of instantaneous temperature responses. In combination with recent experimental findings, we argue that control of mitochondrial electron flow is shared among cytochrome oxidase and alternative oxidase under in vivo conditions, and is continuously coordinated. In this way, upstream carbohydrate metabolism and downstream electron transport appear to be optimized according to the demand of ATP, TCA-cycle intermediates and anabolic reducing power under differing metabolic states. We provide a link to the 'Growth and Maintenance Paradigm' of respiration and argue that respiratory temperature responses can be used as a tool to probe metabolic states of plant tissue, such that we can learn more about the mechanisms that govern longer-term acclimatization responses of plant metabolism.

  8. NAD(P)H oxidase and renal epithelial ion transport

    PubMed Central

    Schreck, Carlos

    2011-01-01

    A fundamental requirement for cellular vitality is the maintenance of plasma ion concentration within strict ranges. It is the function of the kidney to match urinary excretion of ions with daily ion intake and nonrenal losses to maintain a stable ionic milieu. NADPH oxidase is a source of reactive oxygen species (ROS) within many cell types, including the transporting renal epithelia. The focus of this review is to describe the role of NADPH oxidase-derived ROS toward local renal tubular ion transport in each nephron segment and to discuss how NADPH oxidase-derived ROS signaling within the nephron may mediate ion homeostasis. In each case, we will attempt to identify the various subunits of NADPH oxidase and reactive oxygen species involved and the ion transporters, which these affect. We will first review the role of NADPH oxidase on renal Na+ and K+ transport. Finally, we will review the relationship between tubular H+ efflux and NADPH oxidase activity. PMID:21270341

  9. The obligate respiratory supercomplex from Actinobacteria.

    PubMed

    Kao, Wei-Chun; Kleinschroth, Thomas; Nitschke, Wolfgang; Baymann, Frauke; Neehaul, Yashvin; Hellwig, Petra; Richers, Sebastian; Vonck, Janet; Bott, Michael; Hunte, Carola

    2016-10-01

    Actinobacteria are closely linked to human life as industrial producers of bioactive molecules and as human pathogens. Respiratory cytochrome bcc complex and cytochrome aa3 oxidase are key components of their aerobic energy metabolism. They form a supercomplex in the actinobacterial species Corynebacterium glutamicum. With comprehensive bioinformatics and phylogenetic analysis we show that genes for cyt bcc-aa3 supercomplex are characteristic for Actinobacteria (Actinobacteria and Acidimicrobiia, except the anaerobic orders Actinomycetales and Bifidobacteriales). An obligatory supercomplex is likely, due to the lack of genes encoding alternative electron transfer partners such as mono-heme cyt c. Instead, subunit QcrC of bcc complex, here classified as short di-heme cyt c, will provide the exclusive electron transfer link between the complexes as in C. glutamicum. Purified to high homogeneity, the C. glutamicum bcc-aa3 supercomplex contained all subunits and cofactors as analyzed by SDS-PAGE, BN-PAGE, absorption and EPR spectroscopy. Highly uniform supercomplex particles in electron microscopy analysis support a distinct structural composition. The supercomplex possesses a dimeric stoichiometry with a ratio of a-type, b-type and c-type hemes close to 1:1:1. Redox titrations revealed a low potential bcc complex (Em(ISP)=+160mV, Em(bL)=-291mV, Em(bH)=-163mV, Em(cc)=+100mV) fined-tuned for oxidation of menaquinol and a mixed potential aa3 oxidase (Em(CuA)=+150mV, Em(a/a3)=+143/+317mV) mediating between low and high redox potential to accomplish dioxygen reduction. The generated molecular model supports a stable assembled supercomplex with defined architecture which permits energetically efficient coupling of menaquinol oxidation and dioxygen reduction in one supramolecular entity.

  10. New decoding methods of interleaved burst error-correcting codes

    NASA Astrophysics Data System (ADS)

    Nakano, Y.; Kasahara, M.; Namekawa, T.

    1983-04-01

    A probabilistic method of single burst error correction, using the syndrome correlation of subcodes which constitute the interleaved code, is presented. This method makes it possible to realize a high capability of burst error correction with less decoding delay. By generalizing this method it is possible to obtain probabilistic method of multiple (m-fold) burst error correction. After estimating the burst error positions using syndrome correlation of subcodes which are interleaved m-fold burst error detecting codes, this second method corrects erasure errors in each subcode and m-fold burst errors. The performance of these two methods is analyzed via computer simulation, and their effectiveness is demonstrated.

  11. The first BATSE gamma-ray burst catalog

    NASA Technical Reports Server (NTRS)

    Fishman, Gerald J.; Meegan, Charles A.; Wilson, Robert B.; Brock, Martin N.; Horack, John M.; Kouveliotou, Chryssa; Howard, Sethanne; Paciesas, William S.; Briggs, Michael S.; Pendleton, Geoffrey N.

    1994-01-01

    The Burst and Transient Source Experiment on the Compton Gamma-Ray Observatory detected 260 cosmic gamma-ray bursts during the period 19 Apr 1991 to 5 Mar 1992. This paper presents the occurrence times, locations, peak count rates, peak fluxes, fluences, durations, and plots of time histories for these bursts. The angular distribution is consistent with isotropy. The intensity distribution shows a deficit in the number of weak bursts, which is not consistent with a homogeneous distribution of burst sources in Euclidean space. The duration distribution shows evidence for a separate class of bursts with durations less than about 2 seconds.

  12. A continuum model of transcriptional bursting

    PubMed Central

    Corrigan, Adam M; Tunnacliffe, Edward; Cannon, Danielle; Chubb, Jonathan R

    2016-01-01

    Transcription occurs in stochastic bursts. Early models based upon RNA hybridisation studies suggest bursting dynamics arise from alternating inactive and permissive states. Here we investigate bursting mechanism in live cells by quantitative imaging of actin gene transcription, combined with molecular genetics, stochastic simulation and probabilistic modelling. In contrast to early models, our data indicate a continuum of transcriptional states, with a slowly fluctuating initiation rate converting the gene between different levels of activity, interspersed with extended periods of inactivity. We place an upper limit of 40 s on the lifetime of fluctuations in elongation rate, with initiation rate variations persisting an order of magnitude longer. TATA mutations reduce the accessibility of high activity states, leaving the lifetime of on- and off-states unchanged. A continuum or spectrum of gene states potentially enables a wide dynamic range for cell responses to stimuli. DOI: http://dx.doi.org/10.7554/eLife.13051.001 PMID:26896676

  13. Arc burst pattern analysis fault detection system

    NASA Technical Reports Server (NTRS)

    Russell, B. Don (Inventor); Aucoin, B. Michael (Inventor); Benner, Carl L. (Inventor)

    1997-01-01

    A method and apparatus are provided for detecting an arcing fault on a power line carrying a load current. Parameters indicative of power flow and possible fault events on the line, such as voltage and load current, are monitored and analyzed for an arc burst pattern exhibited by arcing faults in a power system. These arcing faults are detected by identifying bursts of each half-cycle of the fundamental current. Bursts occurring at or near a voltage peak indicate arcing on that phase. Once a faulted phase line is identified, a comparison of the current and voltage reveals whether the fault is located in a downstream direction of power flow toward customers, or upstream toward a generation station. If the fault is located downstream, the line is de-energized, and if located upstream, the line may remain energized to prevent unnecessary power outages.

  14. Gamma-Ray Burst Intensity Distributions

    NASA Technical Reports Server (NTRS)

    Band, David L.; Norris, Jay P.; Bonnell, Jerry T.

    2004-01-01

    We use the lag-luminosity relation to calculate self-consistently the redshifts, apparent peak bolometric luminosities L(sub B1), and isotropic energies E(sub iso) for a large sample of BATSE bursts. We consider two different forms of the lag-luminosity relation; for both forms the median redshift, for our burst database is 1.6. We model the resulting sample of burst energies with power law and Gaussian dis- tributions, both of which are reasonable models. The power law model has an index of a = 1.76 plus or minus 0.05 (95% confidence) as opposed to the index of a = 2 predicted by the simple universal jet profile model; however, reasonable refinements to this model permit much greater flexibility in reconciling predicted and observed energy distributions.

  15. Unveiling the secrets of gamma ray bursts

    NASA Astrophysics Data System (ADS)

    Gomboc, Andreja

    2012-07-01

    Gamma Ray Bursts are unpredictable and brief flashes of gamma rays that occur about once a day in random locations in the sky. Since gamma rays do not penetrate the Earth's atmosphere, they are detected by satellites, which automatically trigger ground-based telescopes for follow-up observations at longer wavelengths. In this introduction to Gamma Ray Bursts we review how building a multi-wavelength picture of these events has revealed that they are the most energetic explosions since the Big Bang and are connected with stellar deaths in other galaxies. However, in spite of exceptional observational and theoretical progress in the last 15 years, recent observations raise many questions which challenge our understanding of these elusive phenomena. Gamma Ray Bursts therefore remain one of the hottest topics in modern astrophysics.

  16. Prompt Radio Emission from Gamma Ray Bursts

    NASA Astrophysics Data System (ADS)

    Gotthardt, Noelle

    2010-02-01

    Gamma-ray bursts have been observed, but these enigmatic objects are yet unexplained. These short duration events are undoubtedly due to high-energy events. Fading optical emission and even radio emission has been observed from such events, but prompt radio emission from these events would be very useful in pinning down the physics of the bursts, the nature of the progenitor object,and possibly the medium in which it occurs. If these phenomena occur at large redshifts, there is the possibility that the observations could probe the Epoch of Reionization, or the intergalactic medium. A number of models have been proposed to explain the gamma-ray bursts, ranging from compact object mergers, to maser-like coherent emission. These models are not well constrained by current observations. Prompt radio emission may be detected by a transient radio array. I will discuss a planned search for such signals by the Eight-meter-wavelength Transient Array (ETA). )

  17. Fuzzy correlations of gamma-ray bursts

    NASA Technical Reports Server (NTRS)

    Hartmann, Dieter H.; Linder, Eric V.; Blumenthal, George R.

    1991-01-01

    The origin of gamma-ray bursts is not known, both in the sense of the nature of the source emitting the radiation and literally, the position of the burst on the sky. Lacking unambiguously identified counterparts in any wavelength band studied to date, statistical approaches are required to determine the burster distance scale. Angular correlation analysis is one of the most powerful tools in this regard. However, poor detector resolution gives large localization errors, effectively beam smearing the positions. The resulting fuzzy angular correlation function is investigated and the generic isotropization that smearing induces on any intrinsic clustering is discussed. In particular, the extent to which gamma-ray burst observations by the BATSE detector aboard the Gamma-Ray Observatory might recover an intrinsic source correlation is investigated.

  18. Theory of type IIIb solar radio bursts

    NASA Technical Reports Server (NTRS)

    Smith, R. A.; De La Noe, J.

    1976-01-01

    During the initial space-time evolution of an electron beam injected into the corona, the strong beam-plasma interaction occurs at the head of the beam, leading to the amplification of a quasi-monochromatic large-amplitude plasma wave that stabilizes by trapping the beam particles. Oscillation of the trapped particles in the wave troughs amplifies sideband electrostatic waves. The sidebands and the main wave subsequently decay to observable transverse electromagnetic waves through the parametric decay instability. This process gives rise to the elementary striation bursts. Owing to velocity dispersion in the beam and the density gradient of the corona, the entire process may repeat at a finite number of discrete plasma levels, producing chains of elementary bursts. All the properties of the type IIIb bursts are accounted for in the context of the theory.

  19. Interaction function of coupled bursting neurons

    NASA Astrophysics Data System (ADS)

    Xia, Shi; Jiadong, Zhang

    2016-06-01

    The interaction functions of electrically coupled Hindmarsh-Rose (HR) neurons for different firing patterns are investigated in this paper. By applying the phase reduction technique, the phase response curve (PRC) of the spiking neuron and burst phase response curve (BPRC) of the bursting neuron are derived. Then the interaction function of two coupled neurons can be calculated numerically according to the PRC (or BPRC) and the voltage time course of the neurons. Results show that the BPRC is more and more complicated with the increase of the spike number within a burst, and the curve of the interaction function oscillates more and more frequently with it. However, two certain things are unchanged: ϕ = 0, which corresponds to the in-phase synchronization state, is always the stable equilibrium, while the anti-phase synchronization state with ϕ = 0.5 is an unstable equilibrium. Project supported by the National Natural Science Foundation of China (Grant Nos. 11272065 and 11472061).

  20. Respiratory factors limiting exercise.

    PubMed

    Bye, P T; Farkas, G A; Roussos, C

    1983-01-01

    The question of respiratory factors limiting exercise has been examined in terms of possible limitations arising from the function of gas exchange, the respiratory mechanics, the energetics of the respiratory muscles, or the development of respiratory muscle fatigue. Exercise capacity is curtailed in the presence of marked hypoxia, and this is readily observed in patients with chronic airflow limitation and interstitial lung disease and in some athletes at high intensities of exercise. In patients with interstitial lung disease, gas exchange abnormality--partly the result of diffusion disequilibrium for oxygen transfer--occurs during exercise despite abnormally high ventilations. In contrast, in certain athletes arterial hypoxemia has been documented during heavy exercise, apparently as a result of relative hypoventilation. During strenuous exercise the maximum expiratory flow volume curves are attained both by patients with chronic airflow limitation and by normal subjects, in particular when they breathe dense gas, so that a mechanical constraint is imposed on further increases in ventilation. Similarly, the force velocity characteristics of the inspiratory muscles may also impose a constraint to further increases in inspiratory flows that affects the ability to increase ventilation. In addition, the oxygen cost of maintaining high ventilations is large. Analysis of results from blood flow experiments reveal a substantial increase in blood flow to the respiratory muscles during exercise, with the result that oxygen supply to the rest of the body may be lessened. Alternatively, high exercise ventilations may not be sustained indefinitely owing to the development of respiratory muscle fatigue that results in hypoventilation and reduced arterial oxygen tension.

  1. Swift Burst Alert Telescope (BAT) Instrument Response

    NASA Technical Reports Server (NTRS)

    Parsons, A.; Hullinger, D.; Markwardt, C.; Barthelmy, S.; Cummings, J.; Gehrels, N.; Krimm, H.; Tueller, J.; Fenimore, E.; Palmer, D.

    2004-01-01

    The Burst Alert Telescope (BAT), a large coded aperture instrument with a wide field-of-view (FOV), provides the gamma-ray burst triggers and locations for the Swift Gamma-Ray Burst Explorer. In addition to providing this imaging information, BAT will perform a 15 keV - 150 keV all-sky hard x-ray survey based on the serendipitous pointings resulting from the study of gamma-ray bursts and will also monitor the sky for transient hard x-ray sources. For BAT to provide spectral and photometric information for the gamma-ray bursts, the transient sources and the all-sky survey, the BAT instrument response must be determined to an increasingly greater accuracy. In this talk, we describe the BAT instrument response as determined to an accuracy suitable for gamma-ray burst studies. We will also discuss the public data analysis tools developed to calculate the BAT response to sources at different energies and locations in the FOV. The level of accuracy required for the BAT instrument response used for the hard x-ray survey is significantly higher because this response must be used in the iterative clean algorithm for finding fainter sources. Because the bright sources add a lot of coding noise to the BAT sky image, fainter sources can be seen only after the counts due to the bright sources are removed. The better we know the BAT response, the lower the noise in the cleaned spectrum and thus the more sensitive the survey. Since the BAT detector plane consists of 32768 individual, 4 mm square CZT gamma-ray detectors, the most accurate BAT response would include 32768 individual detector response functions to separate mask modulation effects from differences in detector efficiencies! We describe OUT continuing work to improve the accuracy of the BAT instrument response and will present the current results of Monte Carlo simulations as well as BAT ground calibration data.

  2. Cytochrome o (cyoABCDE) and d (cydAB) oxidase gene expression in Escherichia coli is regulated by oxygen, pH, and the fnr gene product

    SciTech Connect

    Cotter, P.A.; Gunsalus, R.P. ); Chepuri, V.; Gennis, R.B. )

    1990-11-01

    The aerobic respiratory chain of Escherichia coli contains two terminal oxidases that catalyze the oxidation of ubiquinol-8 and the reduction of oxygen to water. They are the cytochrome o oxidase complex encoded by cyoABCDE and the cytochrome d oxidase complex encoded by cydAB. To determine how these genes are regulated in response to a variety of environmental stimuli, including oxygen, we examined their expression by using lacZ protein fusions in wild-type and fnr mutant strains of E. coli. Based on the pattern of anaerobic cydAB expression observed, we propose the existence of a second, as yet unidentified, regulatory element that must function either to activate cydAB expression as oxygen becomes limiting or to repress cydAB expression aerobically. Whereas cytochrome o oxidase encoded by cyoABCDE appears to be produced only under oxygen-rich growth conditions, in keeping with its biochemical properties, cytochrome d oxidase is expressed moderately aerobically and is elevated yet further when oxygen becomes limiting so that the organism can cope better under oxygen starvation conditions. We also examined cyoABCDE and cydAB expression in response to growth on alternative carbon compounds and to changes in the culture medium pH and osmolarity.

  3. Investigation of primordial black hole bursts using interplanetary network gamma-ray bursts

    DOE PAGES

    Ukwatta, Tilan Niranjan; Hurley, Kevin; MacGibbon, Jane H.; ...

    2016-07-25

    The detection of a gamma-ray burst (GRB) in the solar neighborhood would have very important implications for GRB phenomenology. The leading theories for cosmological GRBs would not be able to explain such events. The final bursts of evaporating primordial black holes (PBHs), however, would be a natural explanation for local GRBs. We present a novel technique that can constrain the distance to GRBs using detections from widely separated, non-imaging spacecraft. This method can determine the actual distance to the burst if it is local. We applied this method to constrain distances to a sample of 36 short-duration GRBs detected bymore » the Interplanetary Network (IPN) that show observational properties that are expected from PBH evaporations. These bursts have minimum possible distances in the 1013–1018 cm (7–105 au) range, which are consistent with the expected PBH energetics and with a possible origin in the solar neighborhood, although none of the bursts can be unambiguously demonstrated to be local. Furthermore, assuming that these bursts are real PBH events, we estimate lower limits on the PBH burst evaporation rate in the solar neighborhood.« less

  4. Investigation of primordial black hole bursts using interplanetary network gamma-ray bursts

    SciTech Connect

    Ukwatta, Tilan Niranjan; Hurley, Kevin; MacGibbon, Jane H.; Svinkin, D. S.; Aptekar, R. L.; Golenetskii, S. V.; Frederiks, D. D.; Pal'Shin, V. D.; Goldsten, J.; Boynton, W.; Kozyrev, A. S.; Rau, A.; von Kienlin, A.; Zhang, X.; Connaughton, V.; Yamaoka, K.; Ohno, M.; Ohmori, N.; Feroci, M.; Cline, T.; Gehrels, N.; Krimm, H. A.; McTiernan, J.

    2016-07-25

    The detection of a gamma-ray burst (GRB) in the solar neighborhood would have very important implications for GRB phenomenology. The leading theories for cosmological GRBs would not be able to explain such events. The final bursts of evaporating primordial black holes (PBHs), however, would be a natural explanation for local GRBs. We present a novel technique that can constrain the distance to GRBs using detections from widely separated, non-imaging spacecraft. This method can determine the actual distance to the burst if it is local. We applied this method to constrain distances to a sample of 36 short-duration GRBs detected by the Interplanetary Network (IPN) that show observational properties that are expected from PBH evaporations. These bursts have minimum possible distances in the 1013–1018 cm (7–105 au) range, which are consistent with the expected PBH energetics and with a possible origin in the solar neighborhood, although none of the bursts can be unambiguously demonstrated to be local. Furthermore, assuming that these bursts are real PBH events, we estimate lower limits on the PBH burst evaporation rate in the solar neighborhood.

  5. BATSE observations of gamma-ray burst spectra. 2: Peak energy evolution in bright, long bursts

    NASA Technical Reports Server (NTRS)

    Ford, L. A.; Band, D. L.; Matteson, J. L.; Briggs, M. S.; Pendleton, G. N.; Preece, R. D.; Paciesas, W. S.; Teegarden, B. J.; Palmer, D. M.; Schaefer, B. E.

    1995-01-01

    We investigate spectral evolution in 37 bright, long gamma-ray bursts observed with the Burst and Transient Source Experiment (BATSE) spectroscopy detectors. High-resolution spectra are chracterized by the energy of the peak of nu F(sub nu), and the evolution of this quantity is examined relative to the emission intensity. In most cases it is found that this peak energy either rises with or slightly precedes major intensity increases and softens for the remainder of the pulse. Interpulse emission is generally harder early in the burst. For bursts with multiple intensity pulses, later spikes tend to be softer than earlier ones, indicating that the energy of the peak of nu F(sub nu) is bounded by an envelope which decays with time. Evidence is found that bursts in which the bulk of the flux comes well after the event which triggers the instrument tend to show less peak energy variability and are not as hard as several bursts in which the emission occurs promptly after the trigger. Several recently proposed burst models are examined in light of these results and no qualitative conflicts with the observations presented here are found.

  6. Co-regulation of mitochondrial respiration by proline dehydrogenase/oxidase and succinate.

    PubMed

    Hancock, Chad N; Liu, Wei; Alvord, W Gregory; Phang, James M

    2016-03-01

    Proline dehydrogenase/oxidase (PRODH/POX) is a mitochondrial protein critical to multiple stress pathways. Because of the roles of PRODH/POX in signaling, and its shared localization to the mitochondrial inner membrane with the electron transport chain (ETC), we investigated whether there was a direct relationship between PRODH/POX and regulation of the ETC. We found that PRODH/POX binds directly to CoQ1 and that CoQ1-dependent PRODH/POX activity required functional Complex III and Complex IV. PRODH/POX supported respiration in living cells during nutrient stress; however, expression of PRODH/POX resulted in an overall decrease in respiratory fitness. Effects on respiratory fitness were inhibited by DHP and NAC, indicating that these effects were mediated by PRODH/POX-dependent reactive oxygen species (ROS) generation. PRODH/POX expression resulted in a dose-dependent down-regulation of Complexes I-IV of the ETC, and this effect was also mitigated by the addition of DHP and NAC. We found that succinate was an uncompetitive inhibitor of PRODH/POX activity, inhibited ROS generation by PRODH/POX, and alleviated PRODH/POX effects on respiratory fitness. The findings demonstrate novel cross-talk between proline and succinate respiration in vivo and provide mechanistic insights into observations from previous animal studies. Our results suggest a potential regulatory loop between PRODH/POX and succinate in regulation of mitochondrial respiration.

  7. Processor Reformats Data For Transmission In Bursts

    NASA Technical Reports Server (NTRS)

    Steele, Glen F.

    1991-01-01

    Data-processor-and-buffer electronic system receives audio signals digitized in first standard format at relatively low data rate, rearranges data for transmission in bursts in second standard format at relatively high rate, stores second-format bursts, and releases them at higher rate upon request. Conceived for asynchronous, one-way transmission of digitized speech in outer-space communications, concept of system applied in other digital communication systems in which data transmitted from low-rate sources to high-rate sinks not synchronized with sources.

  8. Noise from aerial bursts of fireworks

    NASA Technical Reports Server (NTRS)

    Maglieri, D. J.; Henderson, H. R.

    1973-01-01

    A study was made recording the pressure time histories of the aerial bursts of mortars of various sizes launched during an actual fireworks display. The peak overpressure and duration of blast noise as well as the energy spectral density are compared with the characteristics of a blasting cap and of an F-104 aircraft at a Mach number of 1.4 and an altitude of 42,000 ft. Noise levels of the fireworks aerial bursts peaked 15 decibels below levels deemed damaging to hearing.

  9. Supernovae and Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Livio, Mario; Panagia, Nino; Sahu, Kailash

    2001-07-01

    Participants; Preface; Gamma-ray burst-supernova relation B. Paczynski; Observations of gamma-ray bursts G. Fishman; Fireballs T. Piran; Gamma-ray mechanisms M. Rees; Prompt optical emission from gamma-ray bursts R. Kehoe, C. Akerlof, R. Balsano, S. Barthelmy, J. Bloch, P. Butterworth, D. Casperson, T. Cline, S. Fletcher, F. Frontera, G. Gisler, J. Heise, J. Hills, K. Hurley, B. Lee, S. Marshall, T. McKay, A. Pawl, L. Piro, B. Priedhorsky, J. Szymanski and J. Wren; X-ray afterglows of gamma-ray bursts L. Piro; The first year of optical-IR observations of SN1998bw I. Danziger, T. Augusteijn, J. Brewer, E. Cappellaro, V. Doublier, T. Galama, J. Gonzalez, O. Hainaut, B. Leibundgut, C. Lidman, P. Mazzali, K. Nomoto, F. Patat, J. Spyromilio, M. Turatto, J. Van Paradijs, P. Vreeswijk and J. Walsh; X-ray emission of Supernova 1998bw in the error box of GRB980425 E. Pian; Direct analysis of spectra of type Ic supernovae D. Branch; The interaction of supernovae and gamma-ray bursts with their surroundings R. Chevalier; Magnetars, soft gamma-ray repeaters and gamma-ray bursts A. Harding; Super-luminous supernova remnants Y. -H. Chu, C. -H. Chen and S. -P. Lai; The properties of hypernovae: SNe Ic 1998bw, 1997ef, and SN IIn 1997cy K. Nomoto, P. Mazzali, T. Nakamura, K. Iwanmoto, K. Maeda, T. Suzuki, M. Turatto, I. Danziger and F. Patat; Collapsars, Gamma-Ray Bursts, and Supernovae S. Woosley, A. MacFadyen and A. Heger; Pre-supernova evolution of massive stars N. Panagia and G. Bono; Radio supernovae and GRB 980425 K. Weiler, N. Panagia, R. Sramek, S. Van Dyk, M. Montes and C. Lacey; Models for Ia supernovae and evolutionary effects P. Hoflich and I. Dominguez; Deflagration to detonation A. Khokhlov; Universality in SN Iae and the Phillips relation D. Arnett; Abundances from supernovae F. -K. Thielemann, F. Brachwitz, C. Freiburghaus, S. Rosswog, K. Iwamoto, T. Nakamura, K. Nomoto, H. Umeda, K. Langanke, G. Martinez-Pinedo, D. Dean, W. Hix and M. Strayer; Sne, GRBs, and the

  10. Simmer analysis of prompt burst energetics experiments

    SciTech Connect

    Hitchcock, J.T.

    1982-03-01

    The Prompt Burst Energetics experiments are designed to measure the pressure behavior of fuel and coolant as working fluids during a hypothetical prompt burst disassembly in an LMFBR. The work presented in this report consists of a parametric study of PBE-5S, a fresh oxide fuel experiment, using SIMMER-II. The various pressure sources in the experiment are examined, and the dominant source identified as incondensable contaminant gasses in the fuel. The important modeling uncertainties and limitations of SIMMER-II as applied to these experiments are discussed.

  11. Exploratory depth-of-burst experiments

    SciTech Connect

    Reichenbach, H.; Behrens, K.; Kuhl, A.

    1991-12-12

    This report describes the first small-scale explosion experiments with aerated grout (i.e., YTONG). Apart from data referring to crater depth and volume versus depth of burst (DOB), isobaric DOB curves in the range of 1.5 psi {le} p {le} 15 psi were established. The comparison with previous HOB values shows that the ground range to a given overpressure is considerably reduced with increasing depth of burst. The authors plan to continue the airblast investigations with different types of soil materials.

  12. Mimicking a SURF1 allele reveals uncoupling of cytochrome c oxidase assembly from translational regulation in yeast.

    PubMed

    Reinhold, Robert; Bareth, Bettina; Balleininger, Martina; Wissel, Mirjam; Rehling, Peter; Mick, David U

    2011-06-15

    Defects in mitochondrial energy metabolism lead to severe human disorders, mainly affecting tissues especially dependent on oxidative phosphorylation, such as muscle and brain. Leigh Syndrome describes a severe encephalomyopathy in infancy, frequently caused by mutations in SURF1. SURF1, termed Shy1 in Saccharomyces cerevisiae, is a conserved assembly factor for the terminal enzyme of the respiratory chain, cytochrome c oxidase. Although the molecular function of SURF1/Shy1 is still enigmatic, loss of function leads to cytochrome c oxidase deficiency and reduced expression of the central subunit Cox1 in yeast. Here, we provide insights into the molecular mechanisms leading to disease through missense mutations in codons of the most conserved amino acids in SURF1. Mutations affecting G(124) do not compromise import of the SURF1 precursor protein but lead to fast turnover of the mature protein within the mitochondria. Interestingly, an Y(274)D exchange neither affects stability nor localization of the protein. Instead, SURF1(Y274D) accumulates in a 200 kDa cytochrome c oxidase assembly intermediate. Using yeast as a model, we demonstrate that the corresponding Shy1(Y344D) is able to overcome the stage where cytochrome c oxidase assembly links to the feedback regulation of mitochondrial Cox1 expression. However, Shy1(Y344D) impairs the assembly at later steps, most apparent at low temperature and exhibits a dominant-negative phenotype upon overexpression. Thus, exchanging the conserved tyrosine (Y(344)) with aspartate in yeast uncouples translational regulation of Cox1 from cytochrome c oxidase assembly and provides evidence for the dual functionality of Shy1.

  13. Tumor necrosis factor receptor-associated protein 1 improves hypoxia-impaired energy production in cardiomyocytes through increasing activity of cytochrome c oxidase subunit II.

    PubMed

    Xiang, Fei; Ma, Si-Yuan; Zhang, Dong-Xia; Zhang, Qiong; Huang, Yue-Sheng

    2016-10-01

    Tumor necrosis factor receptor-associated protein 1 protects cardiomyocytes against hypoxia, but the underlying mechanisms are not completely understood. In the present study, we used gain- and loss-of-function approaches to explore the effects of tumor necrosis factor receptor-associated protein 1 and cytochrome c oxidase subunit II on energy production in hypoxic cardiomyocytes. Hypoxia repressed ATP production in cultured cardiomyocytes, whereas overexpression of tumor necrosis factor receptor-associated protein 1 significantly improved ATP production. Conversely, knockdown of tumor necrosis factor receptor-associated protein 1 facilitated the hypoxia-induced decrease in ATP synthesis. Further investigation revealed that tumor necrosis factor receptor-associated protein 1 induced the expression and activity of cytochrome c oxidase subunit II, a component of cytochrome c oxidase that is important in mitochondrial respiratory chain function. Moreover, lentiviral-mediated overexpression of cytochrome c oxidase subunit II antagonized the decrease in ATP synthesis caused by knockdown of tumor necrosis factor receptor-associated protein 1, whereas knockdown of cytochrome c oxidase subunit II attenuated the increase in ATP synthesis caused by overexpression of tumor necrosis factor receptor-associated protein 1. In addition, inhibition of cytochrome c oxidase subunit II by a specific inhibitor sodium azide suppressed the ATP sy nthesis induced by overexpressed tumor necrosis factor receptor-associated protein 1. Hence, tumor necrosis factor receptor-associated protein 1 protects cardiomyocytes from hypoxia at least partly via potentiation of energy generation, and cytochrome c oxidase subunit II is one of the downstream effectors that mediates the tumor necrosis factor receptor-associated protein 1-mediated energy generation program.

  14. Spectral Tests of the Homogeneity of Gamma-Ray Bursts

    NASA Technical Reports Server (NTRS)

    Band, David L.

    1999-01-01

    We proposed to determine whether the spectral-hardness-intensity relation found when comparing dim and bright bursts is also found within the set of bright bursts. In the simplest cosmological burst paradigm all bursts have the same intrinsic brightness (they are "standard candles") and the faintest BATSE bursts are at a redshift of approx. 1. The cumulative intensity distribution, which is a -3/2 power law at the bright end but flatter at the low intensity end, is explained by the cosmological curvature of space. Thus bursts at the bright end should be at such low redshifts that they do not suffer cosmological redshifting of their spectra or time dilation of their lightcurves. The spectral-hardness and burst intensity are correlated when dim and bright bursts are compared, consistent with cosmological redshifting. However, the actual redshifts of a number of bursts have been determined, showing that bursts are not standard candles, and that their redshifts are frequently greater than approx. 1; the maximum redshift is 3.4! Consequently many bright bursts are at redshifts where cosmological effects are significant. We had proposed to determine A,hether the redshifting effect continued into the bright bursts; even moderately bright bursts should be at cosmological distances.

  15. Individual variation in hepatic aldehyde oxidase activity.

    PubMed

    Al-Salmy, H S

    2001-04-01

    Aldehyde oxidase (AO) is a molybdo-flavo enzyme expressed predominantly in the liver, lung, and kidney. AO plays a major role in oxidation of aldehydes, as well as oxidation of various N-heterocyclic compounds of pharmacological and toxicological importance including antiviral (famciclovir), antimalarial (quinine), antitumour (methotrexate), and nicotine. The aim of this study was to investigate cytosolic aldehyde oxidase activity in human liver. Cytosolic AO was characterised using both the metabolism of N-[(2-dimethylamino)ethyl] acridine-4-carboxamide (DACA) and benzaldehyde to form DACA-9(10H)-acridone (quantified by HPLC with fluorescence detection) and benzoic acid (quantified spectrophotometrically). Thirteen livers (10 female, 3 male) were examined. The intrinsic clearance (Vmax/Km) of DACA varied 18-fold (0.03-0.50 m/min/mg). Vmax ranged from 0.20-3.10 nmol/ min/mg, and Km ranged from 3.5-14.2 microM. In the same specimens, the intrinsic clearance for benzaldehyde varied 5-fold (0.40-1.8 ml/min/mg). Vmax ranged from 3.60-12.6 nmol/min/mg and Km ranged from 3.6-14.6 microM. Furthermore, there were no differences in AO activity between male and female human livers, nor was there any relationship to age of donor (range 29-73 years), smoking status, or disease status. In conclusion, our results showed that there are variations in AO activity in human liver. These variations in aldehyde oxidase activity might reflect individual variations or they might be due to AO stability during processing and storage.

  16. Nox NADPH Oxidases and the Endoplasmic Reticulum

    PubMed Central

    Araujo, Thaís L.S.; Abrahão, Thalita B.

    2014-01-01

    Abstract Significance: Understanding isoform- and context-specific subcellular Nox reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase compartmentalization allows relevant functional inferences. This review addresses the interplay between Nox NADPH oxidases and the endoplasmic reticulum (ER), an increasingly evident player in redox pathophysiology given its role in redox protein folding and stress responses. Recent Advances: Catalytic/regulatory transmembrane subunits are synthesized in the ER and their processing includes folding, N-glycosylation, heme insertion, p22phox heterodimerization, as shown for phagocyte Nox2. Dual oxidase (Duox) maturation also involves the regulation by ER-resident Duoxa2. The ER is the activation site for some isoforms, typically Nox4, but potentially other isoforms. Such location influences redox/Nox-mediated calcium signaling regulation via ER targets, such as sarcoendoplasmic reticulum calcium ATPase (SERCA). Growing evidence suggests that Noxes are integral signaling elements of the unfolded protein response during ER stress, with Nox4 playing a dual prosurvival/proapoptotic role in this setting, whereas Nox2 enhances proapoptotic signaling. ER chaperones such as protein disulfide isomerase (PDI) closely interact with Noxes. PDI supports growth factor-dependent Nox1 activation and mRNA expression, as well as migration in smooth muscle cells, and PDI overexpression induces acute spontaneous Nox activation. Critical Issues: Mechanisms of PDI effects include possible support of complex formation and RhoGTPase activation. In phagocytes, PDI supports phagocytosis, Nox activation, and redox-dependent interactions with p47phox. Together, the results implicate PDI as possible Nox organizer. Future Directions: We propose that convergence between Noxes and ER may have evolutive roots given ER-related functional contexts, which paved Nox evolution, namely calcium signaling and pathogen killing. Overall, the interplay between

  17. Powerful Radio Burst Indicates New Astronomical Phenomenon

    NASA Astrophysics Data System (ADS)

    2007-09-01

    Astronomers studying archival data from an Australian radio telescope have discovered a powerful, short-lived burst of radio waves that they say indicates an entirely new type of astronomical phenomenon. Region of Strong Radio Burst Visible-light (negative greyscale) and radio (contours) image of Small Magellanic Cloud and area where burst originated. CREDIT: Lorimer et al., NRAO/AUI/NSF Click on image for high-resolution file ( 114 KB) "This burst appears to have originated from the distant Universe and may have been produced by an exotic event such as the collision of two neutron stars or the death throes of an evaporating black hole," said Duncan Lorimer, Assistant Professor of Physics at West Virginia University (WVU) and the National Radio Astronomy Observatory (NRAO). The research team led by Lorimer consists of Matthew Bailes of Swinburne University in Australia, Maura McLaughlin of WVU and NRAO, David Narkevic of WVU, and Fronefield Crawford of Franklin and Marshall College in Lancaster, Pennsylvania. The astronomers announced their findings in the September 27 issue of the online journal Science Express. The startling discovery came as WVU undergraduate student David Narkevic re-analyzed data from observations of the Small Magellanic Cloud made by the 210-foot Parkes radio telescope in Australia. The data came from a survey of the Magellanic Clouds that included 480 hours of observations. "This survey had sought to discover new pulsars, and the data already had been searched for the type of pulsating signals they produce," Lorimer said. "We re-examined the data, looking for bursts that, unlike the usual ones from pulsars, are not periodic," he added. The survey had covered the Magellanic Clouds, a pair of small galaxies in orbit around our own Milky Way Galaxy. Some 200,000 light-years from Earth, the Magellanic Clouds are prominent features in the Southern sky. Ironically, the new discovery is not part of these galaxies, but rather is much more distant

  18. Inhibition of NADPH oxidase activation by 4-(2-aminoethyl)-benzenesulfonyl fluoride and related compounds.

    PubMed

    Diatchuk, V; Lotan, O; Koshkin, V; Wikstroem, P; Pick, E

    1997-05-16

    The elicitation of an oxidative burst in phagocytes rests on the assembly of a multicomponental complex (NADPH oxidase) consisting of a membrane-associated flavocytochrome (cytochrome b559), representing the redox element responsible for the NADPH-dependent reduction of oxygen to superoxide (O-2), two cytosolic components (p47(phox), p67(phox)), and the small GTPase Rac (1 or 2). We found that 4-(2-aminoethyl)-benzenesulfonyl fluoride (AEBSF), an irreversible serine protease inhibitor, prevented the elicitation of O-2 production in intact macrophages and the amphiphile-dependent activation of NADPH oxidase in a cell-free system, consisting of solubilized membrane or purified cytochrome b559 combined with total cytosol or a mixture of recombinant p47(phox), p67(phox), and Rac1. AEBSF acted at the activation step and did not interfere with the ensuing electron flow. It did not scavenge oxygen radicals and did not affect assay reagents. Five other serine protease inhibitors (three irreversible and two reversible) were found to lack an inhibitory effect on cell-free activation of NADPH oxidase. A structure-function study of AEBSF analogues demonstrated that the presence of a sulfonyl fluoride group was essential for inhibitory activity and that compounds containing an aminoalkylbenzene moiety were more active than amidinobenzene derivatives. Exposure of the membrane fraction or of purified cytochrome b559, but not of cytosol or recombinant cytosolic components, to AEBSF, in the presence of a critical concentration of the activating amphiphile lithium dodecyl sulfate, resulted in a marked impairment of their ability to support cell-free NADPH oxidase activation upon complementation with untreated cytosol or cytosolic components. Kinetic analysis of the effect of varying the concentration of each of the three cytosolic components on the inhibitory potency of AEBSF indicated that this was inversely related to the concentrations of p47(phox) and, to a lesser degree, p67

  19. Separation of putrescine oxidase and spermidine oxidase in foetal bovine serum with the aid of a specific radioactive assay of spermidine oxidase.

    PubMed Central

    Gahl, W A; Vale, A M; Pitot, H C

    1980-01-01

    1. A sensitive and specific assay for spermidine oxidase is described. The method involves the separation of [14C]spermidine (substrate) from [14C]putrescine (product) and other 14C-labelled products on a Dowex 50 cation-exchange column: 92% of the putrescine applied to the column was eluted by 2.3 M-HCl, but this treatment left 96% of the spermidine bound to the column. Unchanged spermidine could be removed from the column by elution with 6 M-HCl. 2. By means of this assay, foetal and adult bovine serum were each shown to contain spermidine oxidase activity, putrescine being a major product of the oxidation of spermidine by the serum enzymes. 3. In foetal bovine serum, spermidine oxidase activity is separable from putrescine oxidase activity by chromatography on a cadaverine-Sephadex column, by gel filtration and by ion-exchange column chromatography. Putrescine oxidase was purified 1900-fold and spermidine oxidase 130-fold by these procedures. The former oxidized putrescine but not spermidine, and spermidine oxidase exhibited no activity with putrescine as substrate. PMID:7406861

  20. [Respiratory complications after transfusion].

    PubMed

    Bernasinski, M; Mertes, P-M; Carlier, M; Dupont, H; Girard, M; Gette, S; Just, B; Malinovsky, J-M

    2014-05-01

    Respiratory complications of blood transfusion have several possible causes. Transfusion-Associated Circulatory Overload (TACO) is often the first mentioned. Transfusion-Related Acute Lung Injury (TRALI), better defined since the consensus conference of Toronto in 2004, is rarely mentioned. French incidence is low. Non-hemolytic febrile reactions, allergies, infections and pulmonary embolism are also reported. The objective of this work was to determine the statistical importance of the different respiratory complications of blood transfusion. This work was conducted retrospectively on transfusion accidents in six health centers in Champagne-Ardenne, reported to Hemovigilance between 2000 and 2009 and having respiratory symptoms. The analysis of data was conducted by an expert committee. Eighty-three cases of respiratory complications are found (316,864 blood products). We have counted 26 TACO, 12 TRALI (only 6 cases were identified in the original investigation of Hemovigilance), 18 non-hemolytic febrile reactions, 16 cases of allergies, 5 transfusions transmitted bacterial infections and 2 pulmonary embolisms. Six new TRALI were diagnosed previously labeled TACO for 2 of them, allergy and infection in 2 other cases and diagnosis considered unknown for the last 2. Our study found an incidence of TRALI 2 times higher than that reported previously. Interpretation of the data by a multidisciplinary committee amended 20% of diagnoses. This study shows the imperfections of our system for reporting accidents of blood transfusion when a single observer analyses the medical records.

  1. Obesity and respiratory diseases.

    PubMed

    Zammit, Christopher; Liddicoat, Helen; Moonsie, Ian; Makker, Himender

    2010-10-20

    The obesity epidemic is a global problem, which is set to increase over time. However, the effects of obesity on the respiratory system are often underappreciated. In this review, we will discuss the mechanical effects of obesity on lung physiology and the function of adipose tissue as an endocrine organ producing systemic inflammation and effecting central respiratory control. Obesity plays a key role in the development of obstructive sleep apnea and obesity hypoventilation syndrome. Asthma is more common and often harder to treat in the obese population, and in this study, we review the effects of obesity on airway inflammation and respiratory mechanics. We also discuss the compounding effects of obesity on chronic obstructive pulmonary disease (COPD) and the paradoxical interaction of body mass index and COPD severity. Many practical challenges exist in caring for obese patients, and we highlight the complications faced by patients undergoing surgical procedures, especially given the increased use of bariatric surgery. Ultimately, a greater understanding of the effects of obesity on the respiratory disease and the provision of adequate health care resources is vital in order to care for this increasingly important patient population.

  2. Obesity and respiratory diseases

    PubMed Central

    Zammit, Christopher; Liddicoat, Helen; Moonsie, Ian; Makker, Himender

    2010-01-01

    The obesity epidemic is a global problem, which is set to increase over time. However, the effects of obesity on the respiratory system are often underappreciated. In this review, we will discuss the mechanical effects of obesity on lung physiology and the function of adipose tissue as an endocrine organ producing systemic inflammation and effecting central respiratory control. Obesity plays a key role in the development of obstructive sleep apnea and obesity hypoventilation syndrome. Asthma is more common and often harder to treat in the obese population, and in this study, we review the effects of obesity on airway inflammation and respiratory mechanics. We also discuss the compounding effects of obesity on chronic obstructive pulmonary disease (COPD) and the paradoxical interaction of body mass index and COPD severity. Many practical challenges exist in caring for obese patients, and we highlight the complications faced by patients undergoing surgical procedures, especially given the increased use of bariatric surgery. Ultimately, a greater understanding of the effects of obesity on the respiratory disease and the provision of adequate health care resources is vital in order to care for this increasingly important patient population. PMID:21116339

  3. Textbook of respiratory medicine

    SciTech Connect

    Murray, J.F.; Nadel, J.

    1987-01-01

    This book presents a clinical reference of respiratory medicine. It also details basic science aspects of pulmonary physiology and describes recently developed, sophisticated diagnostic tools and therapeutic methods. It also covers anatomy, physiology, pharmacology, and pathology; microbiologic, radiologic, nuclear medicine, and biopsy methods for diagnosis.

  4. Respiratory muscle plasticity.

    PubMed

    Gransee, Heather M; Mantilla, Carlos B; Sieck, Gary C

    2012-04-01

    Muscle plasticity is defined as the ability of a given muscle to alter its structural and functional properties in accordance with the environmental conditions imposed on it. As such, respiratory muscle is in a constant state of remodeling, and the basis of muscle's plasticity is its ability to change protein expression and resultant protein balance in response to varying environmental conditions. Here, we will describe the changes of respiratory muscle imposed by extrinsic changes in mechanical load, activity, and innervation. Although there is a large body of literature on the structural and functional plasticity of respiratory muscles, we are only beginning to understand the molecular-scale protein changes that contribute to protein balance. We will give an overview of key mechanisms regulating protein synthesis and protein degradation, as well as the complex interactions between them. We suggest future application of a systems biology approach that would develop a mathematical model of protein balance and greatly improve treatments in a variety of clinical settings related to maintaining both muscle mass and optimal contractile function of respiratory muscles.

  5. Middle East respiratory syndrome.

    PubMed

    Zumla, Alimuddin; Hui, David S; Perlman, Stanley

    2015-09-05

    Middle East respiratory syndrome (MERS) is a highly lethal respiratory disease caused by a novel single-stranded, positive-sense RNA betacoronavirus (MERS-CoV). Dromedary camels, hosts for MERS-CoV, are implicated in direct or indirect transmission to human beings, although the exact mode of transmission is unknown. The virus was first isolated from a patient who died from a severe respiratory illness in June, 2012, in Jeddah, Saudi Arabia. As of May 31, 2015, 1180 laboratory-confirmed cases (483 deaths; 40% mortality) have been reported to WHO. Both community-acquired and hospital-acquired cases have been reported with little human-to-human transmission reported in the community. Although most cases of MERS have occurred in Saudi Arabia and the United Arab Emirates, cases have been reported in Europe, the USA, and Asia in people who travelled from the Middle East or their contacts. Clinical features of MERS range from asymptomatic or mild disease to acute respiratory distress syndrome and multiorgan failure resulting in death, especially in individuals with underlying comorbidities. No specific drug treatment exists for MERS and infection prevention and control measures are crucial to prevent spread in health-care facilities. MERS-CoV continues to be an endemic, low-level public health threat. However, the virus could mutate to have increased interhuman transmissibility, increasing its pandemic potential.

  6. THE FIVE YEAR FERMI/GBM MAGNETAR BURST CATALOG

    SciTech Connect

    Collazzi, A. C.; Kouveliotou, C.; Horst, A. J. van der; Younes, G. A.; Kaneko, Y.; Göğüş, E.; Lin, L.; Granot, J.; Finger, M. H.; Chaplin, V. L.; Huppenkothen, D.; Watts, A. L.; Kienlin, A. von; Baring, M. G.; Gruber, D.; Bhat, P. N.; Gibby, M. H.; and others

    2015-05-15

    Since launch in 2008, the Fermi Gamma-ray Burst Monitor (GBM) has detected many hundreds of bursts from magnetar sources. While the vast majority of these bursts have been attributed to several known magnetars, there is also a small sample of magnetar-like bursts of unknown origin. Here, we present the Fermi/GBM magnetar catalog, providing the results of the temporal and spectral analyses of 440 magnetar bursts with high temporal and spectral resolution. This catalog covers the first five years of GBM magnetar observations, from 2008 July to 2013 June. We provide durations, spectral parameters for various models, fluences, and peak fluxes for all the bursts, as well as a detailed temporal analysis for SGR J1550–5418 bursts. Finally, we suggest that some of the bursts of unknown origin are associated with the newly discovered magnetar 3XMM J185246.6+0033.7.

  7. Swift's Christmas Burst From Blue Supergiant Star Explosion

    NASA Video Gallery

    GRB 101225A, better known as the "Christmas burst," was an unusually long-lasting gamma-ray burst. Because its distance was not measured, astronomers came up with two radically different interpreta...

  8. Gamma-Ray Bursts in the Swift Era

    NASA Technical Reports Server (NTRS)

    Gehrels, Neil; Ramirez-Ruiz, E.; Fox, D. B.

    2010-01-01

    With its rapid-response capability and multiwavelength complement of instruments, the Swift satellite has transformed our physical understanding of gamma-ray bursts. Providing high-quality observations of hundreds of bursts, and facilitating a wide range of follow-up observations within seconds of each event, Swift has revealed an unforeseen richness in observed burst properties, shed light on the nature of short-duration bursts, and helped realize the promise of gamma-ray bursts as probes of the processes and environments of star formation out to the earliest cosmic epochs. These advances have opened new perspectives on the nature and properties of burst central engines, interactions with the burst environment from microparsec to gigaparsec scales, and the possibilities for non-photonic signatures. Our understanding of these extreme cosmic sources has thus advanced substantially; yet more than forty years after their discovery, gamma-ray bursts continue to present major challenges on both observational and theoretical fronts.

  9. Power Enhancement Cavity for Burst-Mode Laser Pulses

    SciTech Connect

    Liu, Yun

    2015-01-01

    We demonstrate a novel optical cavity scheme and locking method that can realize the power enhancement of picosecond UV laser pulses operating at a burst mode with arbitrary burst (macropulse) lengths and repetition rates.

  10. Statistical Properties of SGR 1806-20 Bursts

    NASA Technical Reports Server (NTRS)

    Gogus, E.; Woods, P.; Kouveliotou, C.; VanParadijs, J.; Briggs, M. S.; Duncan, R. C.; Thompson, C.

    1999-01-01

    We find that the fluence distribution of bursts observed with each instrument are well described by power laws with indices 1.43, 1.67 and 1.76 respectively. The distribution of time intervals between successive bursts from SGR 1806-20 is described by a lognormal function with peak at 97 s. There is no correlation between burst intensity and either the waiting times till the next burst or the time elapsed since the previous burst, We find a correlation between the duration and fluence of the bursts, but with substantial scatter. In all these statistical properties, SGR bursts resemble self-organized critical systems, such as earthquakes and solar flares. Our results thus support the hypothesis that the energy source for SGR bursts is crustquakes due to the magnetic field of the neutron star, rather than any accretion- or nuclear-power.

  11. The Five Year Fermi/GBM Magnetar Burst Catalog

    NASA Astrophysics Data System (ADS)

    Collazzi, A. C.; Kouveliotou, C.; van der Horst, A. J.; Younes, G. A.; Kaneko, Y.; Göğüş, E.; Lin, L.; Granot, J.; Finger, M. H.; Chaplin, V. L.; Huppenkothen, D.; Watts, A. L.; von Kienlin, A.; Baring, M. G.; Gruber, D.; Bhat, P. N.; Gibby, M. H.; Gehrels, N.; McEnery, J.; van der Klis, M.; Wijers, R. A. M. J.

    2015-05-01

    Since launch in 2008, the Fermi Gamma-ray Burst Monitor (GBM) has detected many hundreds of bursts from magnetar sources. While the vast majority of these bursts have been attributed to several known magnetars, there is also a small sample of magnetar-like bursts of unknown origin. Here, we present the Fermi/GBM magnetar catalog, providing the results of the temporal and spectral analyses of 440 magnetar bursts with high temporal and spectral resolution. This catalog covers the first five years of GBM magnetar observations, from 2008 July to 2013 June. We provide durations, spectral parameters for various models, fluences, and peak fluxes for all the bursts, as well as a detailed temporal analysis for SGR J1550-5418 bursts. Finally, we suggest that some of the bursts of unknown origin are associated with the newly discovered magnetar 3XMM J185246.6+0033.7.

  12. THE FERMI-GBM X-RAY BURST MONITOR: THERMONUCLEAR BURSTS FROM 4U 0614+09

    SciTech Connect

    Linares, M.; Chakrabarty, D.; Connaughton, V.; Bhat, P. N.; Briggs, M. S.; Preece, R.; Jenke, P.; Kouveliotou, C.; Wilson-Hodge, C. A.; Camero-Arranz, A.; Finger, M.; Paciesas, W. S.; Beklen, E.; Von Kienlin, A.

    2012-12-01

    Thermonuclear bursts from slowly accreting neutron stars (NSs) have proven difficult to detect, yet they are potential probes of the thermal properties of the NS interior. During the first year of a systematic all-sky search for X-ray bursts using the Gamma-ray Burst Monitor aboard the Fermi Gamma-ray Space Telescope we have detected 15 thermonuclear bursts from the NS low-mass X-ray binary 4U 0614+09 when it was accreting at nearly 1% of the Eddington limit. We measured an average burst recurrence time of 12 {+-} 3 days (68% confidence interval) between 2010 March and 2011 March, classified all bursts as normal duration bursts and placed a lower limit on the recurrence time of long/intermediate bursts of 62 days (95% confidence level). We discuss how observations of thermonuclear bursts in the hard X-ray band compare to pointed soft X-ray observations and quantify such bandpass effects on measurements of burst radiated energy and duration. We put our results for 4U 0614+09 in the context of other bursters and briefly discuss the constraints on ignition models. Interestingly, we find that the burst energies in 4U 0614+09 are on average between those of normal duration bursts and those measured in long/intermediate bursts. Such a continuous distribution in burst energy provides a new observational link between normal and long/intermediate bursts. We suggest that the apparent bimodal distribution that defined normal and long/intermediate duration bursts during the last decade could be due to an observational bias toward detecting only the longest and most energetic bursts from slowly accreting NSs.

  13. NADPH Oxidase Promotes Neutrophil Extracellular Trap Formation in Pulmonary Aspergillosis

    PubMed Central

    Röhm, Marc; Grimm, Melissa J.; D'Auria, Anthony C.; Almyroudis, Nikolaos G.

    2014-01-01

    NADPH oxidase is a crucial enzyme in antimicrobial host defense and in regulating inflammation. Chronic granulomatous disease (CGD) is an inherited disorder of NADPH oxidase in which phagocytes are defective in generation of reactive oxidant intermediates. Aspergillus species are ubiquitous, filamentous fungi, which can cause invasive aspergillosis, a major cause of morbidity and mortality in CGD, reflecting the critical role for NADPH oxidase in antifungal host defense. Activation of NADPH oxidase in neutrophils can be coupled to the release of proteins and chromatin that comingle in neutrophil extracellular traps (NETs), which can augment extracellular antimicrobial host defense. NETosis can be driven by NADPH oxidase-dependent and -independent pathways. We therefore undertook an analysis of whether NADPH oxidase was required for NETosis in Aspergillus fumigatus pneumonia. Oropharyngeal instillation of live Aspergillus hyphae induced neutrophilic pneumonitis in both wild-type and NADPH oxidase-deficient (p47phox−/−) mice which had resolved in wild-type mice by day 5 but progressed in p47phox−/− mice. NETs, identified by immunostaining, were observed in lungs of wild-type mice but were absent in p47phox−/− mice. Using bona fide NETs and nuclear chromatin decondensation as an early NETosis marker, we found that NETosis required a functional NADPH oxidase in vivo and ex vivo. In addition, NADPH oxidase increased the proportion of apoptotic neutrophils. Together, our results show that NADPH oxidase is required for pulmonary clearance of Aspergillus hyphae and generation of NETs in vivo. We speculate that dual modulation of NETosis and apoptosis by NADPH oxidase enhances antifungal host defense and promotes resolution of inflammation upon infection clearance. PMID:24549323

  14. Multicopper oxidase-1 orthologs from diverse insect species have ascorbate oxidase activity.

    PubMed

    Peng, Zeyu; Dittmer, Neal T; Lang, Minglin; Brummett, Lisa M; Braun, Caroline L; Davis, Lawrence C; Kanost, Michael R; Gorman, Maureen J

    2015-04-01

    Members of the multicopper oxidase (MCO) family of enzymes can be classified by their substrate specificity; for example, ferroxidases oxidize ferrous iron, ascorbate oxidases oxidize ascorbate, and laccases oxidize aromatic substrates such as diphenols. Our previous work on an insect multicopper oxidase, MCO1, suggested that it may function as a ferroxidase. This hypothesis was based on three lines of evidence: RNAi-mediated knock down of Drosophila melanogaster MCO1 (DmMCO1) affects iron homeostasis, DmMCO1 has ferroxidase activity, and DmMCO1 has predicted iron binding residues. In our current study, we expanded our focus to include MCO1 from Anopheles gambiae, Tribolium castaneum, and Manduca sexta. We verified that MCO1 orthologs have similar expression profiles, and that the MCO1 protein is located on the basal surface of cells where it is positioned to oxidize substrates in the hemolymph. In addition, we determined that RNAi-mediated knock down of MCO1 in A. gambiae affects iron homeostasis. To further characterize the enzymatic activity of MCO1 orthologs, we purified recombinant MCO1 from all four insect species and performed kinetic analyses using ferrous iron, ascorbate and two diphenols as substrates. We found that all of the MCO1 orthologs are much better at oxidizing ascorbate than they are at oxidizing ferrous iron or diphenols. This result is surprising because ascorbate oxidases are thought to be specific to plants and fungi. An analysis of three predicted iron binding residues in DmMCO1 revealed that they are not required for ferroxidase or laccase activity, but two of the residues (His374 and Asp380) influence oxidation of ascorbate. These two residues are conserved in MCO1 orthologs from insects and crustaceans; therefore, they are likely to be important for MCO1 function. The results of this study suggest that MCO1 orthologs function as ascorbate oxidases and influence iron homeostasis through an unknown mechanism.

  15. Multicopper oxidase-1 orthologs from diverse insect species have ascorbate oxidase activity

    PubMed Central

    Peng, Zeyu; Dittmer, Neal T.; Lang, Minglin; Brummett, Lisa M.; Braun, Caroline L.; Davis, Lawrence C.; Kanost, Michael R.; Gorman, Maureen J.

    2015-01-01

    Members of the multicopper oxidase (MCO) family of enzymes can be classified by their substrate specificity; for example, ferroxidases oxidize ferrous iron, ascorbate oxidases oxidize ascorbate, and laccases oxidize aromatic substrates such as diphenols. Our previous work on an insect multicopper oxidase, MCO1, suggested that it may function as a ferroxidase. This hypothesis was based on three lines of evidence: RNAi-mediated knock down of Drosophila melanogaster MCO1 (DmMCO1) affects iron homeostasis, DmMCO1 has ferroxidase activity, and DmMCO1 has predicted iron binding residues. In our current study, we expanded our focus to include MCO1 from Anopheles gambiae, Tribolium castaneum, and Manduca sexta. We verified that MCO1 orthologs have similar expression profiles, and that the MCO1 protein is located on the basal surface of cells where it is positioned to oxidize substrates in the hemolymph. In addition, we determined that RNAi-mediated knock down of MCO1 in A. gambiae affects iron homeostasis. To further characterize the enzymatic activity of MCO1 orthologs, we purified recombinant MCO1 from all four insect species and performed kinetic analyses using ferrous iron, ascorbate and two diphenols as substrates. We found that all of the MCO1 orthologs are much better at oxidizing ascorbate than they are at oxidizing ferrous iron or diphenols. This result is surpring because ascorbate oxidases are thought to be specific to plants and fungi. An analysis of three predicted iron binding residues in DmMCO1 revealed that they are not required for ferroxidase or laccase activity, but two of the residues (His374 and Asp380) influence oxidation of ascorbate. These two residues are conserved in MCO1 orthologs from insects and crustaceans; therefore, they are likely to be important for MCO1 function. The results of this study suggest that MCO1 orthologs function as ascorbate oxidases and influence iron homeostasis through an unknown mechanism. PMID:25701385

  16. Serotonergic mechanisms are necessary for central respiratory chemoresponsiveness in situ

    PubMed Central

    Corcoran, Andrea E.; Richerson, George B.; Harris, Michael B.

    2013-01-01

    Evidence from in vivo and in vitro experiments conclude that serotonin (5-HT) neurons are involved in and play an important role in central respiratory CO2/H+ chemosensitivity. This study was designed to assess the importance of 5-HT neurons and 5-HT receptor activation in the frequency and amplitude components of the hypercapnic response of the respiratory network in the unanesthetized perfused in situ juvenile rat brainstem preparation that exhibits patterns of phrenic nerve discharge similar to breathing in vivo. Exposure to a hypercapnic perfusate increased phrenic burst frequency and/or amplitude, the neural correlates of breathing frequency and tidal volume in vivo. Hypercapnic responses were also assessed during exposure to ketanserin (5-HT2 receptor antagonist), and 8-OH-DPAT (inhibiting 5-HT neurons via 5-HT1A autoreceptors). Neither of these drugs substantially altered baseline activity, however, both abolished hypercapnic responses of the respiratory network. These data illustrate that 5-HT neurons and 5-HT receptor activation are not required for respiratory rhythm generation per se, but are critical for CO2 responses in situ, supporting the hypothesis that 5-HT neurons play an important role in central ventilatory chemosensitivity in vivo. PMID:23454177

  17. Search for bursts in air shower data

    NASA Technical Reports Server (NTRS)

    Bruce, T. E. G.; Clay, R. W.; Dawson, B. R.; Protheroe, R. J.; Blair, D. G.; Cinquini, P.

    1985-01-01

    There have been reports in recent years of the possible observation of bursts in air shower data. If such events are truly of an astrophysical nature then, they represent an important new class of phemonenon since no other bursts have been observed above the MeV level. The spectra of conventional gamma ray bursts are unknown at higher energies but their observed spectra at MeV energies appear generally to exhibit a steepening in the higher MeV range and are thus unlikely to extrapolate to measurable fluxes at air shower energies. An attempt has been made to look for deviations from randomness in the arrival times of air showers above approx. 10 to the 14th power eV with a number of systems and results so far are presented here. This work will be continued for a substantial period of ime with a system capable of recording bursts with multiple events down to a spacing of 4 microns. Earlier data have also been searched for the possible association of air shower events with a glitch of the Vela pulsar.

  18. Gamma-Ray Bursts and Cosmology

    NASA Technical Reports Server (NTRS)

    Norris, Jay P.

    2003-01-01

    The unrivalled, extreme luminosities of gamma-ray bursts (GRBs) make them the favored beacons for sampling the high redshift Universe. To employ GRBs to study the cosmic terrain -- e.g., star and galaxy formation history -- GRB luminosities must be calibrated, and the luminosity function versus redshift must be measured or inferred. Several nascent relationships between gamma-ray temporal or spectral indicators and luminosity or total energy have been reported. These measures promise to further our understanding of GRBs once the connections between the luminosity indicators and GRB jets and emission mechanisms are better elucidated. The current distribution of 33 redshifts determined from host galaxies and afterglows peaks near z $\\sim$ 1, whereas for the full BATSE sample of long bursts, the lag-luminosity relation predicts a broad peak z $\\sim$ 1--4 with a tail to z $\\sim$ 20, in rough agreement with theoretical models based on star formation considerations. For some GRB subclasses and apparently related phenomena -- short bursts, long-lag bursts, and X-ray flashes -- the present information on their redshift distributions is sparse or entirely lacking, and progress is expected in Swift era when prompt alerts become numerous.

  19. ASTRONOMY: Neighborhood Gamma Ray Burst Boosts Theory.

    PubMed

    Schilling, G

    2000-07-07

    Titanic explosions that emit powerful flashes of energetic gamma rays are one of astronomy's hottest mysteries. Now an analysis of the nearest gamma ray burst yet detected has added weight to the popular theory that they are expelled during the death throes of supermassive stars.

  20. Bursts of Chromosome Changes Drive TNBC.

    PubMed

    2016-10-01

    A recent study suggests that complex genomic rearrangements in triple-negative breast cancer cells occur through a "Big Bang" model-early, short bursts of copy number aberrations, rather than progressive accumulation over time. Afterward, these aberrations are stably maintained in a handful of clones that expand to form the tumor mass.

  1. Short-burst oxygen therapy for COPD patients: a 6-month randomised, controlled study.

    PubMed

    Eaton, T; Fergusson, W; Kolbe, J; Lewis, C A; West, T

    2006-04-01

    Short-burst oxygen therapy (SBOT) remains widely advocated for patients with chronic obstructive pulmonary disease (COPD), despite a lack of supporting evidence. The aim of this randomised, double-blind, placebo-controlled, parallel group study was to determine whether SBOT improves health-related quality of life (HRQL) or reduces acute healthcare utilisation in patients discharged following an acute exacerbation of COPD. Consecutive patients were screened; 78 of 331 were eligible for randomisation to cylinder oxygen, cylinder air or usual care following discharge. Patients were elderly with high acute healthcare utilisation, forced expiratory volume in one second of <1 L and had dyspnoea limiting daily activity but were not hypoxaemic at rest. Over the 6-month study period, there were no significant differences between patient groups in HRQL (Chronic Respiratory Questionnaire (CRQ), 36-item Short-Form Health Survey, Hospital Anxiety and Depression Scale) except for CRQ emotion domain. There were no significant differences in acute healthcare utilisation. Time to readmission was greatest in the usual care group. Cylinder use was high initially, but rapidly fell to very low levels within weeks in both cylinder oxygen and air groups. In conclusion, the availability of short-burst oxygen therapy for chronic obstructive pulmonary disease patients discharged from hospital following an acute exacerbation did not improve health-related quality of life or reduce acute healthcare utilisation. These results provide no support for the widespread use of short-burst oxygen therapy.

  2. Short-burst oxygen immediately before and after exercise is ineffective in nonhypoxic COPD patients.

    PubMed

    Lewis, C A; Eaton, T E; Young, P; Kolbe, J

    2003-10-01

    Short-burst oxygen therapy (SBOT) remains an unproven treatment for reduction of exertional dyspnoea in chronic obstructive pulmonary disease (COPD). This study aimed to assess whether SBOT before exercise reduces dyspnoea or improves performance, and whether SBOT after exercise reduces dyspnoea during recovery. Twenty-two clinically stable COPD patients (mean forced expiratory volume in one second 34% predicted, mean resting saturation 94%) attended a respiratory gymnasium and undertook four 6-min walk (6MW) tests at each of two sessions, 1 week apart. Cylinder air or oxygen was administered single-blind in random order for 5 min prior to the first two 6MW and during recovery following the final two 6MW. Dyspnoea was self-rated by subjects using the modified Borg scale. There was no significant difference in mean 6MW distance or final Borg score for air and oxygen given before exercise. There was also no significant difference in mean time-to-resting Borg score for air and oxygen given after exercise. Only two subjects demonstrated a clinically significant and consistent reduction in dyspnoea for oxygen compared with air either before or after exercise. Overall, short-burst oxygen therapy neither reduced dyspnoea nor improved performance. This study does not support the use of short-burst oxygen therapy either immediately before or after exercise.

  3. Constraints of the Luminosities of Gamma-Ray Bursts

    NASA Astrophysics Data System (ADS)

    Hakkila, J.; Meegan, C.; Horack, J.; Pendleton, G.; Briggs, M.; Paciesas, W.; Emslie, G.; Mallozzi, R.

    1995-09-01

    Constraints are found on the gamma-ray burst luminosity function from an analysis of the combined BATSE/PVO intensity distribution. If bursts originate in an extended Galactic halo, then the intrinsic luminosity range is narrow, with bursts spanning only a factor of five or less in luminosity. If bursts originate in a simple Friedmann cosmology with Ω = 1 and Λ = 0, then very few luminosity constraints exist.

  4. Limited Practice Respiratory Care Course.

    ERIC Educational Resources Information Center

    Anderson, Amy L.

    This 36-46 hour basic respiratory care course has been designed to enhance the skills of health professionals in providing limited respiratory care during those hours when a respiratory care practitioner is not available. Persons taking the course are assumed to have a basic knowledge of anatomy and physiology, administration of medications, and…

  5. Your Lungs and Respiratory System

    MedlinePlus

    ... dientes Video: Getting an X-ray Your Lungs & Respiratory System KidsHealth > For Kids > Your Lungs & Respiratory System Print A A A What's in this article? ... in your body, and they work with your respiratory system to allow you to take in fresh air, ...

  6. BurstMem: A High-Performance Burst Buffer System for Scientific Applications

    SciTech Connect

    Wang, Teng; Oral, H Sarp; Wang, Yandong; Settlemyer, Bradley W; Atchley, Scott; Yu, Weikuan

    2014-01-01

    The growth of computing power on large-scale sys- tems requires commensurate high-bandwidth I/O system. Many parallel file systems are designed to provide fast sustainable I/O in response to applications soaring requirements. To meet this need, a novel system is imperative to temporarily buffer the bursty I/O and gradually flush datasets to long-term parallel file systems. In this paper, we introduce the design of BurstMem, a high- performance burst buffer system. BurstMem provides a storage framework with efficient storage and communication manage- ment strategies. Our experiments demonstrate that BurstMem is able to speed up the I/O performance of scientific applications by up to 8.5 on leadership computer systems.

  7. X-ray observations of the burst source MXB 1728 - 34

    NASA Technical Reports Server (NTRS)

    Basinska, E. M.; Lewin, W. H. G.; Sztajno, M.; Cominsky, L. R.; Marshall, F. J.

    1984-01-01

    Where sufficient information has been obtained, attention is given to the maximum burst flux, integrated burst flux, spectral hardness, rise time, etc., of 96 X-ray bursts observed from March 1976 to March 1979. The integrated burst flux and the burst frequency appear to be correlated; the longer the burst interval, the larger the integrated burst flux, as expected on the basis of simple thermonuclear flash models. The maximum burst flux and the integrated burst flux are strongly correlated; for low flux levels their dependence is approximately linear, while for increasing values of the integrated burst flux, the flux at burst maximum saturates and reaches a plateau.

  8. Xanthine oxidase inhibitors from Garcinia esculenta twigs.

    PubMed

    Zhu, Lun-Lun; Fu, Wen-Wei; Watanabe, Shimpei; Shao, Yi-Nuo; Tan, Hong-Sheng; Zhang, Hong; Tan, Chang-Heng; Xiu, Yan-Feng; Norimoto, Hisayoshi; Xu, Hong-Xi

    2014-12-01

    The EtOAc-soluble portion of the 80 % (v/v) EtOH extract from the twigs of Garcinia esculenta exhibited strong xanthine oxidase inhibition in vitro. Bioassay-guided purification led to the isolation of 1,3,6,7-tetrahydroxyxanthone (3) and griffipavixanthone (8) as the main xanthine oxidase inhibitors, along with six additional compounds (1, 2, 4-7), including two new compounds (1 and 2). This enzyme inhibition was dose dependent with an IC50 value of approximately 1.2 µM for 3 and 6.3 µM for 8. The inhibitory activity of 3 was stronger than the control allopurinol (IC50 value: 5.3 µM). To our knowledge, compound 8 is the first bixanthone that demonstrated potent XO inhibitory activity in vitro. The structures of the new compounds were established by spectroscopic analysis, and the optical properties and absolute stereochemistry of racemic (±) esculentin A (2) were further determined by the calculation of the DP4 probability and analysis of its MTPA ester derivatives.

  9. Solar S-bursts at Frequencies of 10 - 30 MHz

    NASA Astrophysics Data System (ADS)

    Melnik, V. N.; Konovalenko, A. A.; Rucker, H. O.; Dorovskyy, V. V.; Abranin, E. P.; Lecacheux, A.; Lonskaya, A. S.

    2010-06-01

    Solar S-bursts observed by the radio telescope UTR-2 in the period 2001 - 2002 are studied. The bursts chosen for a detailed analysis occurred in the periods 23 - 26 May 2001, 13 - 16 and 27 - 39 July 2002 during three solar radio storms. More than 800 S-bursts were registered in these days. Properties of S-bursts are studied in the frequency band 10 - 30 MHz. All bursts were always observed against a background of other solar radio activity such as type III and IIIb bursts, type III-like bursts, drift pairs and spikes. Moreover, S-bursts were observed during days when the active region was situated near the central meridian. Characteristic durations of S-bursts were about 0.35 and 0.4 - 0.6 s for the May and July storms, respectively. For the first time, we found that the instantaneous frequency width of S-bursts increased with frequency linearly. The dependence of drift rates on frequency followed the McConnell dependence derived for higher frequencies. We propose a model of S-bursts based on the assumption that these bursts are generated due to the confluence of Langmuir waves with fast magnetosonic waves, whose phase and group velocities are equal.

  10. 46 CFR 154.554 - Cargo hose: Bursting pressure.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Cargo hose: Bursting pressure. 154.554 Section 154.554... Hose § 154.554 Cargo hose: Bursting pressure. Cargo hose that may be exposed to the pressure in the cargo tank, the cargo pump discharge, or the vapor compressor discharge must have a bursting pressure...

  11. 46 CFR 154.554 - Cargo hose: Bursting pressure.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 5 2012-10-01 2012-10-01 false Cargo hose: Bursting pressure. 154.554 Section 154.554... Hose § 154.554 Cargo hose: Bursting pressure. Cargo hose that may be exposed to the pressure in the cargo tank, the cargo pump discharge, or the vapor compressor discharge must have a bursting pressure...

  12. 46 CFR 154.554 - Cargo hose: Bursting pressure.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 5 2011-10-01 2011-10-01 false Cargo hose: Bursting pressure. 154.554 Section 154.554... Hose § 154.554 Cargo hose: Bursting pressure. Cargo hose that may be exposed to the pressure in the cargo tank, the cargo pump discharge, or the vapor compressor discharge must have a bursting pressure...

  13. 46 CFR 154.554 - Cargo hose: Bursting pressure.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 5 2013-10-01 2013-10-01 false Cargo hose: Bursting pressure. 154.554 Section 154.554... Hose § 154.554 Cargo hose: Bursting pressure. Cargo hose that may be exposed to the pressure in the cargo tank, the cargo pump discharge, or the vapor compressor discharge must have a bursting pressure...

  14. Gamma ray bursts: Current status of observations and theory

    NASA Technical Reports Server (NTRS)

    Meegan, Charles A.

    1990-01-01

    Gamma ray bursts display a wide range of temporal and spectral characteristics, but typically last several seconds and emit most of their energy in a low energy, gamma ray region. The burst sources appear to be isotropically distributed on the sky. Several lines of evidence suggest magnetic neutron stars as sources for bursts. A variety of energy sources and emission mechanisms are proposed.

  15. 47 CFR 90.250 - Meteor burst communications.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Meteor burst communications. 90.250 Section 90... PRIVATE LAND MOBILE RADIO SERVICES Non-Voice and Other Specialized Operations § 90.250 Meteor burst communications. Meteor burst communications may be authorized for the use of private radio stations subject...

  16. 47 CFR 90.250 - Meteor burst communications.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Meteor burst communications. 90.250 Section 90... PRIVATE LAND MOBILE RADIO SERVICES Non-Voice and Other Specialized Operations § 90.250 Meteor burst communications. Meteor burst communications may be authorized for the use of private radio stations subject...

  17. 47 CFR 90.250 - Meteor burst communications.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Meteor burst communications. 90.250 Section 90... PRIVATE LAND MOBILE RADIO SERVICES Non-Voice and Other Specialized Operations § 90.250 Meteor burst communications. Meteor burst communications may be authorized for the use of private radio stations subject...

  18. 47 CFR 90.250 - Meteor burst communications.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Meteor burst communications. 90.250 Section 90... PRIVATE LAND MOBILE RADIO SERVICES Non-Voice and Other Specialized Operations § 90.250 Meteor burst communications. Meteor burst communications may be authorized for the use of private radio stations subject...

  19. 47 CFR 90.250 - Meteor burst communications.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Meteor burst communications. 90.250 Section 90... PRIVATE LAND MOBILE RADIO SERVICES Non-Voice and Other Specialized Operations § 90.250 Meteor burst communications. Meteor burst communications may be authorized for the use of private radio stations subject...

  20. Temperature-dependent bursting pattern analysis by modified Plant model

    PubMed Central

    2014-01-01

    Many electrophysiological properties of neuron including firing rates and rhythmical oscillation change in response to a temperature variation, but the mechanism underlying these correlations remains unverified. In this study, we analyzed various action potential (AP) parameters of bursting pacemaker neurons in the abdominal ganglion of Aplysia juliana to examine whether or not bursting patterns are altered in response to temperature change. Here we found that the inter-burst interval, burst duration, and number of spike during burst decreased as temperature increased. On the other hand, the numbers of bursts per minute and numbers of spikes per minute increased and then decreased, but interspike interval during burst firstly decreased and then increased. We also tested the reproducibility of temperature-dependent changes in bursting patterns and AP parameters. Finally we performed computational simulations of these phenomena by using a modified Plant model composed of equations with temperature-dependent scaling factors to mathematically clarify the temperature-dependent changes of bursting patterns in burst-firing neurons. Taken together, we found that the modified Plant model could trace the ionic mechanism underlying the temperature-dependent change in bursting pattern from experiments with bursting pacemaker neurons in the abdominal ganglia of Aplysia juliana. PMID:25051923

  1. Climate change and respiratory disease: European Respiratory Society position statement.

    PubMed

    Ayres, J G; Forsberg, B; Annesi-Maesano, I; Dey, R; Ebi, K L; Helms, P J; Medina-Ramón, M; Windt, M; Forastiere, F

    2009-08-01

    Climate change will affect individuals with pre-existing respiratory disease, but the extent of the effect remains unclear. The present position statement was developed on behalf of the European Respiratory Society in order to identify areas of concern arising from climate change for individuals with respiratory disease, healthcare workers in the respiratory sector and policy makers. The statement was developed following a 2-day workshop held in Leuven (Belgium) in March 2008. Key areas of concern for the respiratory community arising from climate change are discussed and recommendations made to address gaps in knowledge. The most important recommendation was the development of more accurate predictive models for predicting the impact of climate change on respiratory health. Respiratory healthcare workers also have an advocatory role in persuading governments and the European Union to maintain awareness and appropriate actions with respect to climate change, and these areas are also discussed in the position statement.

  2. Molecular Evolution of Cytochrome bd Oxidases across Proteobacterial Genomes

    PubMed Central

    Degli Esposti, Mauro; Rosas-Pérez, Tania; Servín-Garcidueñas, Luis Eduardo; Bolaños, Luis Manuel; Rosenblueth, Monica; Martínez-Romero, Esperanza

    2015-01-01

    This work is aimed to resolve the complex molecular evolution of cytochrome bd ubiquinol oxidase, a nearly ubiquitous bacterial enzyme that is involved in redox balance and bioenergetics. Previous studies have created an unclear picture of bd oxidases phylogenesis without considering the existence of diverse types of bd oxidases. Integrated approaches of genomic and protein analysis focused on proteobacteria have generated a molecular classification of diverse types of bd oxidases, which produces a new scenario for interpreting their evolution. A duplication of the original gene cluster of bd oxidase might have occurred in the ancestors of extant α-proteobacteria of the Rhodospirillales order, such as Acidocella, from which the bd-I type of the oxidase might have diffused to other proteobacterial lineages. In contrast, the Cyanide-Insensitive Oxidase type may have differentiated into recognizable subtypes after another gene cluster duplication. These subtypes are widespread in the genomes of α-, β-, and γ-proteobacteria, with occasional instances of lateral gene transfer. In resolving the evolutionary pattern of proteobacterial bd oxidases, this work sheds new light on the basal taxa of α-proteobacteria from which the γ-proteobacterial lineage probably emerged. PMID:25688108

  3. Detection and characterization of a multicopper oxidase from Nitrosomonas europaea.

    PubMed

    Lawton, Thomas J; Rosenzweig, Amy C

    2011-01-01

    Blue copper oxidase (BCO) is a multicopper oxidase (MCO) found in Nitrosomonas europaea as well as in other ammonia-oxidizing organisms. In this chapter, we detail methods used to detect, isolate, and characterize BCO from N. europaea. A method for identifying and classifying MCOs commonly found in nitrifiers based on primary sequence is also described.

  4. Immunological identification of the alternative oxidase of Neurospora crassa mitochondria.

    PubMed Central

    Lambowitz, A M; Sabourin, J R; Bertrand, H; Nickels, R; McIntosh, L

    1989-01-01

    Neurospora crassa mitochondria use a branched electron transport system in which one branch is a conventional cytochrome system and the other is an alternative cyanide-resistant, hydroxamic acid-sensitive oxidase that is induced when the cytochrome system is impaired. We used a monoclonal antibody to the alternative oxidase of the higher plant Sauromatum guttatum to identify a similar set of related polypeptides (Mr, 36,500 and 37,000) that was associated with the alternative oxidase activity of N. crassa mitochondria. These polypeptides were not present constitutively in the mitochondria of a wild-type N. crassa strain, but were produced in high amounts under conditions that induced alternative oxidase activity. Under the same conditions, mutants in the aod-1 gene, with one exception, produced apparently inactive alternative oxidase polypeptides, whereas mutants in the aod-2 gene failed to produce these polypeptides. The latter findings support the hypothesis that aod-1 is a structural gene for the alternative oxidase and that the aod-2 gene encodes a component that is required for induction of alternative oxidase activity. Finally, our results indicate that the alternative oxidase is highly conserved, even between plant and fungal species. Images PMID:2524649

  5. Lysyl oxidase activity in human normal skins and postburn scars.

    PubMed

    Hayakawa, T; Hino, N; Fuyamada, H; Nagatsu, T; Aoyama, H

    1976-09-06

    Lysyl oxidase activity of human normal skins derived from the frontal thighs of 33 subjects showed large variations and the mean value was 11 455 +/- 7 172 (S.D.) cpm/g of wet weight tissue. The age of lesion affected the lysyl oxidase activity in postburn scars. Granulation tissues showed a fairly low activity; however, the activity increased sharply within 2--3 months, and reached a significantly higher value than that of normal skin. The high level of activity continued for up to 2--3 years, then gradually decreased to normal range after 5 years or so. Lysyl oxidase activity was detected only after 4 M urea treatment of tissues. Benzylamine oxidase activity also showed large variations in both normal skins and postburn scars, with mean values of: 0.128 +/- 0.077 (S.D.) and 0.145 +/- 0.090 (S.D.) mmol/g of wet weight/h, respectively. No correlation was observed between lysyl oxidase and benzylamine oxidase activities. The granulation tissues showed significantly high values of benzylamine oxidase activity in contrast to the low values of lysyl oxidase activity.

  6. Protein phosphorylation and prevention of cytochrome oxidase inhibition by ATP: coupled mechanisms of energy metabolism regulation

    PubMed Central

    Acin-Perez, Rebeca; Gatti, Domenico L.; Bai, Yidong; Manfredi, Giovanni

    2011-01-01

    Summary Rapid regulation of oxidative phosphorylation is crucial for mitochondrial adaptation to swift changes in fuels availability and energy demands. An intra-mitochondrial signaling pathway regulates cytochrome oxidase (COX), the terminal enzyme of the respiratory chain, through reversible phosphorylation. We find that PKA-mediated phosphorylation of a COX subunit dictates mammalian mitochondrial energy fluxes, and identify the specific residue (S58) of COX subunit IV-1 (COXIV-1) that is involved in this mechanism of metabolic regulation. Using protein mutagenesis, molecular dynamics simulations, and induced fit docking, we show that mitochondrial energy metabolism regulation by phosphorylation of COXIV-1 is coupled with prevention of COX allosteric inhibition by ATP. This regulatory mechanism is essential for efficient oxidative metabolism and cell survival. We propose that S58 COXIV-1 phosphorylation has evolved as a metabolic switch that allows mammalian mitochondria to rapidly toggle between energy utilization and energy storage. PMID:21641552

  7. Path correlation considered prioritized burst segmentation for quality of service support in optical burst switching networks

    NASA Astrophysics Data System (ADS)

    Hou, Rui; Changyue, Jiana; He, Tingting; Yu, Jianwei; Lei, Bo; Mao, Tengyue

    2013-04-01

    Burst segmentation (BS) is a high-efficiency contention resolution scheme in bufferless optical burst switching (OBS) networks. A prioritized BS scheme for quality of service (QoS) support is developed. Unlike the existing work on the BS scheme, the proposed BS model considers path-correlated factors, such as path length, the adjoining paths carrying traffic on a given path, and the multipriority traffic coming from all paths. Byte loss probability for high-priority and low-priority bursts under the time-based assembly approach and the length-based assembly approach to estimate the performance of the proposed BS scheme by comparing the cumulative distribution function of a burst length in an OBS ingress node (source) with that in an egress node (destination) is introduced. A preemptive BS policy for different priority bursts is proposed to support the QoS of the OBS network. Finally, a simulation is given to validate the proposed analytical model in an existing OBS network with two priority bursts. It is shown that the proposed BS scheme can realize the service differentiation for multipriority traffic under the consideration of network topology-dependent parameters.

  8. Evaluation of a burst aggregation method in an optical burst switched agile all-photonic network

    NASA Astrophysics Data System (ADS)

    Parveen, Sonia; Radziwilowicz, Robert; Paredes, Sofia A.; Hall, Trevor J.

    2005-09-01

    This paper presents a burst aggregation method for an Agile All-Photonic Network (AAPN) operating under an asynchronous burst switched mode. The model combines both the timer-based and threshold-based approaches into a single composite burst assembly mechanism. This is evaluated semi-analytically for fixed length packets and Poisson arrivals and used as a special case to verify a more general OPNET Modeler simulation. The dependence of the blocking probability on different burst aggregation parameters is observed as well. The same procedure is extended to 'encapsulate' (aggregate) variable packet length traffic into 'envelopes' (bursts) matched to the time slots in an AAPN operating in a synchronous time-slotted mode. Results are presented for an emulation of this process using real IP network traffic from the local LAN using two encapsulation methods that differ depending upon whether 'envelope' boundaries are allowed to cross constituent packets or otherwise. Bandwidth utilization was measured for different encapsulation parameters and it is confirmed that the model with the boundaries allowed to cross packets (i.e., the model with packet segmentation) is more bandwidth-efficient even if the processing delay is slightly larger. The successful operation of the emulation system suggests as well that a simple, low-cost software implementation would be suitable to perform the burst/slot aggregation process in AAPN.

  9. Positional characteristics of meter-decameter wavelength bursts associated with hard X-ray bursts

    NASA Technical Reports Server (NTRS)

    Kundu, M. R.; Gergely, T. E.; Kane, S. R.

    1982-01-01

    Isolated and grouped type III bursts have been observed in temporal association with impulsive hard X-ray bursts in the 26-154 keV range, down to frequencies as low as 30 MHz and out to a distance of 3.1 solar radii from the disk center. The bursts occurred in regions whose electron density may have been as much as 20 times higher than that of the Newkirk-Saito model. The present observations indicate that electron acceleration/injection occurs over a region covering a wide range of magnetic field lines. It is noted that, of the two gradual hard X-ray bursts observed in association with type IV bursts, one was accompanied by a type II event, while the other was not, although both exhibited the same characteristics. It is suggested that the gradual burst associated with a type IV only involved electrons which are trapped in the plasmoid which produces the meter-decameter emission, while another fraction of the population is trapped in the low-lying loops which produce the hard X-ray and centimeter radiation.

  10. The dark bursts population in a complete sample of bright Swift long gamma-ray bursts

    NASA Astrophysics Data System (ADS)

    Melandri, A.; Sbarufatti, B.; D'Avanzo, P.; Salvaterra, R.; Campana, S.; Covino, S.; Vergani, S. D.; Nava, L.; Ghisellini, G.; Ghirlanda, G.; Fugazza, D.; Mangano, V.; Capalbi, M.; Tagliaferri, G.

    2012-04-01

    We study the properties of the population of optically dark events present in a carefully selected complete sample of bright Swift long gamma-ray bursts. The high level of completeness in redshift of our sample (52 objects out of 58) allows us to establish the existence of a genuine dark population, and we are able to estimate the maximum fraction of dark burst events (˜30 per cent) expected for the whole class of long gamma-ray burst. The redshift distribution of this population of dark bursts is similar to that of the whole sample. Interestingly, the rest-frame X-ray luminosity (and the de-absorbed X-ray flux) of the subclass of dark bursts is slightly higher than the average luminosity of the non-dark events. At the same time, the prompt properties do not differ and the optical flux of dark events is at the lower tail of the optical flux distribution, corrected for Galactic absorption. All these properties suggest that dark bursts events generate in much denser environments with respect to normal bright events. We can therefore exclude the high-z and the low-density scenarios and conclude that the major cause of the origin of optically dark events is the dust extinction.

  11. Identification, expression, and taxonomic distribution of alternative oxidases in non-angiosperm plants.

    PubMed

    Neimanis, Karina; Staples, James F; Hüner, Norman P A; McDonald, Allison E

    2013-09-10

    Alternative oxidase (AOX) is a terminal ubiquinol oxidase present in the respiratory chain of all angiosperms investigated to date, but AOX distribution in other members of the Viridiplantae is less clear. We assessed the taxonomic distribution of AOX using bioinformatics. Multiple sequence alignments compared AOX proteins and examined amino acid residues involved in AOX catalytic function and post-translational regulation. Novel AOX sequences were found in both Chlorophytes and Streptophytes and we conclude that AOX is widespread in the Viridiplantae. AOX multigene families are common in non-angiosperm plants and the appearance of AOX1 and AOX2 subtypes pre-dates the divergence of the Coniferophyta and Magnoliophyta. Residues involved in AOX catalytic function are highly conserved between Chlorophytes and Streptophytes, while AOX post-translational regulation likely differs in these two lineages. We demonstrate experimentally that an AOX gene is present in the moss Physcomitrella patens and that the gene is transcribed. Our findings suggest that AOX will likely exert an influence on plant respiration and carbon metabolism in non-angiosperms such as green algae, bryophytes, liverworts, lycopods, ferns, gnetophytes, and gymnosperms and that further research in these systems is required.

  12. The complex roles of NADPH oxidases in fungal infection

    PubMed Central

    Hogan, Deborah; Wheeler, Robert T.

    2014-01-01

    Summary NADPH oxidases play key roles in immunity and inflammation that go beyond the production of microbicidal reactive oxygen species (ROS). The past decade has brought a new appreciation for the diversity of roles played by ROS in signaling associated with inflammation and immunity. NADPH oxidase activity affects disease outcome during infections by human pathogenic fungi, an important group of emerging and opportunistic pathogens that includes Candida, Aspergillus and Cryptococcus species. Here we review how alternative roles of NADPH oxidase activity impact fungal infection and how ROS signaling affects fungal physiology. Particular attention is paid to roles for NADPH oxidase in immune migration, immunoregulation in pulmonary infection, neutrophil extracellular trap formation, autophagy and inflammasome activity. These recent advances highlight the power and versatility of spatiotemporally controlled redox regulation in the context of infection, and point to a need to understand the molecular consequences of NADPH oxidase activity in the cell. PMID:24905433

  13. The calcium-dependent protein kinase CPK28 negatively regulates the BIK1-mediated PAMP-induced calcium burst

    PubMed Central

    Monaghan, Jacqueline; Matschi, Susanne; Romeis, Tina; Zipfel, Cyril

    2015-01-01

    Plants are protected from microbial infection by a robust immune system. Two of the earliest responses mediated by surface-localized immune receptors include an increase in cytosolic calcium (Ca2+) and a burst of apoplastic reactive oxygen species (ROS). The Arabidopsis plasma membrane-associated cytoplasmic kinase BIK1 is an immediate convergent substrate of multiple surface-localized immune receptors that is genetically required for the PAMP-induced Ca2+ burst and directly regulates ROS production catalyzed by the NADPH oxidase RBOHD. We recently demonstrated that Arabidopsis plants maintain an optimal level of BIK1 through a process of continuous degradation regulated by the Ca2+-dependent protein kinase CPK28. cpk28 mutants accumulate more BIK1 protein and display enhanced immune signaling, while plants over-expressing CPK28 accumulate less BIK1 protein and display impaired immune signaling. Here, we show that CPK28 additionally contributes to the PAMP-induced Ca2+ burst, supporting its role as a negative regulator of BIK1. PMID:26039480

  14. Type III Radio Burst Duration and SEP Events

    NASA Technical Reports Server (NTRS)

    Gopalswamy, N.; Makela, P.; Xie, H.

    2010-01-01

    Long-duration (>15 min), low-frequency (<14 MHz) type III radio bursts have been reported to be indicative of solar energetic particle events. We measured the durations of type III bursts associated with large SEP events of solar cycle 23. The Type III durations are distributed symmetrically at 1 MHz yielding a mean value of approximately 33 min (median = 32 min) for the large SEP events. When the SEP events with ground level enhancement (GLE,) are considered, the distribution is essentially unchanged (mean = 32 min, median = 30 min). To test the importance of type III bursts in indicating SEP events, we considered a set of six type III bursts from the same active region (AR 10588) whose durations fit the "long duration" criterion. We analyzed the coronal mass ejections (CMEs), flares, and type II radio bursts associated with the type III bursts. The CMEs were of similar speeds and the flares are also of similar size and duration. All but one of the type III bursts was not associated with a type II burst in the metric or longer wavelength domains. The burst without type II burst also lacked a solar energetic particle (SEP) event at energies >25 MeV. The 1-MHz duration of the type III burst (28 rein) is near the median value of type III durations found for gradual SEP events and ground level enhancement (GLE) events. Yet, there was no sign of SEP events. On the other hand, two other type III bursts from the same active region had similar duration but accompanied by WAVES type 11 bursts; these bursts were also accompanied by SEP events detected by SOHO/ERNE. This study suggests that the type III burst duration may not be a good indicator of an SEP event, consistent with the statistical study of Cliver and Ling (2009, ApJ ).

  15. Genotypic Variation in Cytokinin Oxidase from Phaseolus Callus Cultures 1

    PubMed Central

    Kaminek, Miroslav; Armstrong, Donald J.

    1990-01-01

    Genotypic variation in cytokinin oxidase has been detected in enzyme preparations from Phaseolus vulgaris L. cv Great Northern and Phaseolus lunatus L. cv Kingston callus cultures. Although cytokinin oxidase preparations from Great Northern and Kingston callus tissues appear to have very similar substrate specificities, the cytokinin oxidase activities from the two callus tissues were found to differ in a number of other properties. The cytokinin oxidase from P. vulgaris cv Great Northern callus tissue exhibited a pH optimum of 6.5 (bisTris) and had a strong affinity for the lectin concanavalin A. The cytokinin oxidase from P. lunatus cv Kingston callus tissue exhibited a pH optimum of 8.4 (Taps) and did not bind to concanavalin A. The two enzymes also differed in position of elution when chromatographed on DEAE-cellulose. Both cytokinin oxidase activities exhibited enhanced activity and lower pH optima in the presence of copper-imidazole complexes, but the optimum copper-imidazole ratio and the magnitude of enhancement differed for the two activities. In both callus tissues, transient increases in the supply of exogenous cytokinins induced increases in cytokinin oxidase activity. The differences in pH optima and in glycosylation (as evidenced by the observed difference in lectin affinity) of the cytokinin oxidases from Great Northern and Kingston callus tissues suggest that the compartmentation of cytokinin oxidase may differ in the two callus tissues. The possibility that enzyme compartmentation and isozyme variation in cytokinin oxidase may play a role in the regulation of cytokinin degradation in plant tissues is discussed in relation to known differences in the rates of cytokinin degradation in Great Northern and Kingston callus tissues. Images Figure 6 PMID:16667652

  16. Respiratory fluid mechanics

    NASA Astrophysics Data System (ADS)

    Grotberg, James B.

    2011-02-01

    This article covers several aspects of respiratory fluid mechanics that have been actively investigated by our group over the years. For the most part, the topics involve two-phase flows in the respiratory system with applications to normal and diseased lungs, as well as therapeutic interventions. Specifically, the topics include liquid plug flow in airways and at airway bifurcations as it relates to surfactant, drug, gene, or stem cell delivery into the lung; liquid plug rupture and its damaging effects on underlying airway epithelial cells as well as a source of crackling sounds in the lung; airway closure from "capillary-elastic instabilities," as well as nonlinear stabilization from oscillatory core flow which we call the "oscillating butter knife;" liquid film, and surfactant dynamics in an oscillating alveolus and the steady streaming, and surfactant spreading on thin viscous films including our discovery of the Grotberg-Borgas-Gaver shock.

  17. [Asbestos and respiratory diseases].

    PubMed

    Scherpereel, Arnaud

    2016-01-01

    Previous occupational asbestos exposure (more rarely environmental or domestic exposure) may induce various pleural and/or pulmonary, benign or malignant diseases, sometimes with a very long latency for malignant mesothelioma (MM). Asbestos has been widely extracted and used in Western countries and in emerging or developing countries, resulting in a peak of MM incidence in France around 2020 and likely in a world pandemic of asbestos-induced diseases. These patients have mostly benign respiratory diseases (pleural plugs) but may also be diagnosed with lung cancer or malignant pleural mesothelioma, and have a global poor outcome. New therapeutic tools (targeted therapies, immunotherapy…) with first promising results are developed. However, it is crucial to obtain a full ban of asbestos use worldwide, and to do a regular follow-up of asbestos-exposed subjects, mostly if they are already diagnosed with benign respiratory diseases. Finally, new cancers (larynx and ovary) were recently added to the list of asbestos-induced tumors.

  18. Respiratory fluid mechanics

    PubMed Central

    Grotberg, James B.

    2011-01-01

    This article covers several aspects of respiratory fluid mechanics that have been actively investigated by our group over the years. For the most part, the topics involve two-phase flows in the respiratory system with applications to normal and diseased lungs, as well as therapeutic interventions. Specifically, the topics include liquid plug flow in airways and at airway bifurcations as it relates to surfactant, drug, gene, or stem cell delivery into the lung; liquid plug rupture and its damaging effects on underlying airway epithelial cells as well as a source of crackling sounds in the lung; airway closure from “capillary-elastic instabilities,” as well as nonlinear stabilization from oscillatory core flow which we call the “oscillating butter knife;” liquid film, and surfactant dynamics in an oscillating alveolus and the steady streaming, and surfactant spreading on thin viscous films including our discovery of the Grotberg–Borgas–Gaver shock. PMID:21403768

  19. Respiratory fluid mechanics.

    PubMed

    Grotberg, James B

    2011-02-01

    This article covers several aspects of respiratory fluid mechanics that have been actively investigated by our group over the years. For the most part, the topics involve two-phase flows in the respiratory system with applications to normal and diseased lungs, as well as therapeutic interventions. Specifically, the topics include liquid plug flow in airways and at airway bifurcations as it relates to surfactant, drug, gene, or stem cell delivery into the lung; liquid plug rupture and its damaging effects on underlying airway epithelial cells as well as a source of crackling sounds in the lung; airway closure from "capillary-elastic instabilities," as well as nonlinear stabilization from oscillatory core flow which we call the "oscillating butter knife;" liquid film, and surfactant dynamics in an oscillating alveolus and the steady streaming, and surfactant spreading on thin viscous films including our discovery of the Grotberg-Borgas-Gaver shock.

  20. Ocular tropism of respiratory viruses.

    PubMed

    Belser, Jessica A; Rota, Paul A; Tumpey, Terrence M

    2013-03-01

    Respiratory viruses (including adenovirus, influenza virus, respiratory syncytial virus, coronavirus, and rhinovirus) cause a broad spectrum of disease in humans, ranging from mild influenza-like symptoms to acute respiratory failure. While species D adenoviruses and subtype H7 influenza viruses are known to possess an ocular tropism, documented human ocular disease has been reported following infection with all principal respiratory viruses. In this review, we describe the anatomical proximity and cellular receptor distribution between ocular and respiratory tissues. All major respiratory viruses and their association with human ocular disease are discussed. Research utilizing in vitro and in vivo models to study the ability of respiratory viruses to use the eye as a portal of entry as well as a primary site of virus replication is highlighted. Identification of shared receptor-binding preferences, host responses, and laboratory modeling protocols among these viruses provides a needed bridge between clinical and laboratory studies of virus tropism.