Sample records for peroxido acido ativado

  1. Stabilisation of μ-peroxido-bridged Fe(III) intermediates with non-symmetric bidentate N-donor ligands.


    Pap, József S; Draksharapu, Apparao; Giorgi, Michel; Browne, Wesley R; Kaizer, József; Speier, Gábor


    The spectroscopic characterisation of the (μ-1,2-peroxido)diiron(iii) species formed transiently upon reaction of [Fe(ii)(NN)3](2+) complexes with H2O2 by UV/vis absorption and resonance Raman spectroscopy is reported. The intermediacy of such species in the disproportionation of H2O2 is demonstrated.

  2. Novel ternary vanadium-betaine-peroxido species suppresses H-ras and matrix metalloproteinase-2 expression by increasing reactive oxygen species-mediated apoptosis in cancer cells.


    Petanidis, Savvas; Kioseoglou, Efrosini; Hadzopoulou-Cladaras, Margarita; Salifoglou, Athanasios


    Vanadium is known for its antitumorigenicity. Poised to investigate the impact of well-defined forms of vanadium on processes and specific biomolecules (oncogenes-proteins) involved in cancer cell physiology, a novel ternary V(V)-peroxido-betaine compound was employed in experiments targeting cell viability, apoptosis, reactive oxygen species (ROS) production, H-ras signaling, and matrix metalloproteinase-2 (MMP-2) expression in human breast cancer epithelial and lung adenocarcinoma cells. The results reveal that vanadium imparts a significant decrease in cancer cell viability, reducing H-ras and MMP-2 expression by increasing ROS-mediated apoptosis, distinctly emphasizing the nature, structure and properties of ternary ligands on vanadium anti-tumor activity and its future potential as a metallodrug.

  3. Some Biochemical Properties of an Acido-Thermophilic Archae-Bacterium Sulfolobus Acidocaldarius

    NASA Astrophysics Data System (ADS)

    Oshima, Tairo; Ohba, Masayuki; Wagaki, Takayoshi


    To elucidate the phylogenic status of archaebacteria, some basic cellular components of an acido-thermophilic archaebacterium,Sulfolobus acidocaldarius, were studied. Poly(A) containing RNA was present in the cells, and performed the role of mRNA in a cell-free extract of reticulocyte or the archaebacteria. Poly(A) containing RNA was also found in other archaebacterial cells. The absence of cap structure was suggested in these RNAs. The cell-free protein synthesis using the archaebacterial extract was inhibited by anisomycin, a specific inhibitor for eukaryotic ribosomes. Two unique membrane-bound ATPases were detected. Based on resistance to H+-ATPase inhibitors, these enzymes seemed not to be F0F1-ATPase.

  4. Assessing Metabolic Changes in Response to mTOR Inhibition in a Mantle Cell Lymphoma Xenograft Model Using AcidoCEST MRI

    PubMed Central

    Akhenblit, Paul J.; Hanke, Neale T.; Gill, Alexander; Persky, Daniel O.; Howison, Christine M.; Pagel, Mark D.; Baker, Amanda F.


    AcidoCEST magnetic resonance imaging (MRI) has previously been shown to measure tumor extracellular pH (pHe) with excellent accuracy and precision. This study investigated the ability of acidoCEST MRI to monitor changes in tumor pHe in response to therapy. To perform this study, we used the Granta 519 human mantle cell lymphoma cell line, which is an aggressive B-cell malignancy that demonstrates activation of the phosphatidylinositol-3-kinase/Akt/mammalian target of rapamycin (mTOR) pathway. We performed in vitro and in vivo studies using the Granta 519 cell line to investigate the efficacy and associated changes induced by the mTOR inhibitor, everolimus (RAD001). AcidoCEST MRI studies showed a statistically significant increase in tumor pHe of 0.10 pH unit within 1 day of initiating treatment, which foreshadowed a decrease in tumor growth of the Granta 519 xenograft model. AcidoCEST MRI then measured a decrease in tumor pHe 7 days after initiating treatment, which foreshadowed a return to normal tumor growth rate. Therefore, this study is a strong example that acidoCEST MRI can be used to measure tumor pHe that may serve as a marker for therapeutic efficacy of anticancer therapies. PMID:27140422

  5. Respiration gating and Bloch fitting improve pH measurements with acidoCEST MRI in an ovarian orthotopic tumor model

    PubMed Central

    Jones, Kyle M; Randtke, Edward A; Howison, Christine M; Pagel, Mark D


    We have developed a MRI method that can measure extracellular pH in tumor tissues, known as acidoCEST MRI. This method relies on the detection of Chemical Exchange Saturation Transfer (CEST) of iopamidol, an FDA-approved CT contrast agent that has two CEST signals. A log10 ratio of the two CEST signals is linearly correlated with pH, but independent of agent concentration, endogenous T1 relaxation time, and B1 inhomogeneity. Therefore, detecting both CEST effects of iopamidol during in vivo studies can be used to accurately measure the extracellular pH in tumor tissues. Past in vivo studies using acidoCEST MRI have suffered from respiration artifacts in orthotopic and lung tumor models that have corrupted pH measurements. In addition, the non-linear fitting method used to analyze results is unreliable as it is subject to over-fitting especially with noisy CEST spectra. To improve the technique, we have recently developed a respiration gated CEST MRI pulse sequence that has greatly reduced motion artifacts, and we have included both a prescan and post scan to remove endogenous CEST effects. In addition, we fit the results by parameterizing the contrast of the exogenous agent with respect to pH via the Bloch equations modified for chemical exchange, which is less subject to over-fitting than the non-linear method. These advances in the acidoCEST MRI technique and analysis methods have made pH measurements more reliable, especially in areas of the body subject to respiratory motion. PMID:27212783

  6. Respiration gating and Bloch fitting improve pH measurements with acidoCEST MRI in an ovarian orthotopic tumor model

    NASA Astrophysics Data System (ADS)

    Jones, Kyle M.; Randtke, Edward A.; Howison, Christine M.; Pagel, Mark D.


    We have developed a MRI method that can measure extracellular pH in tumor tissues, known as acidoCEST MRI. This method relies on the detection of Chemical Exchange Saturation Transfer (CEST) of iopamidol, an FDA-approved CT contrast agent that has two CEST signals. A log10 ratio of the two CEST signals is linearly correlated with pH, but independent of agent concentration, endogenous T1 relaxation time, and B1 inhomogeneity. Therefore, detecting both CEST effects of iopamidol during in vivo studies can be used to accurately measure the extracellular pH in tumor tissues. Past in vivo studies using acidoCEST MRI have suffered from respiration artifacts in orthotopic and lung tumor models that have corrupted pH measurements. In addition, the non-linear fitting method used to analyze results is unreliable as it is subject to over-fitting especially with noisy CEST spectra. To improve the technique, we have recently developed a respiration gated CEST MRI pulse sequence that has greatly reduced motion artifacts, and we have included both a prescan and post scan to remove endogenous CEST effects. In addition, we fit the results by parameterizing the contrast of the exogenous agent with respect to pH via the Bloch equations modified for chemical exchange, which is less subject to over-fitting than the non-linear method. These advances in the acidoCEST MRI technique and analysis methods have made pH measurements more reliable, especially in areas of the body subject to respiratory motion.

  7. Acido-basic control of the thermoelectric properties of poly(3,4-ethylenedioxythiophene)tosylate (PEDOT-Tos) thin films

    PubMed Central

    Khan, Zia Ullah; Bubnova, Olga; Jafari, Mohammad Javad; Brooke, Robert; Liu, Xianjie; Gabrielsson, Roger; Ederth, Thomas; Evans, Drew R.; Andreasen, Jens W.; Fahlman, Mats


    PEDOT-Tos is one of the conducting polymers that displays the most promising thermoelectric properties. Until now, it has been utterly difficult to control all the synthesis parameters and the morphology governing the thermoelectric properties. To improve our understanding of this material, we study the variation in the thermoelectric properties by a simple acido-basic treatment. The emphasis of this study is to elucidate the chemical changes induced by acid (HCl) or base (NaOH) treatment in PEDOT-Tos thin films using various spectroscopic and structural techniques. We could identify changes in the nanoscale morphology due to anion exchange between tosylate and Cl– or OH–. But, we identified that changing the pH leads to a tuning of the oxidation level of the polymer, which can explain the changes in thermoelectric properties. Hence, a simple acid–base treatment allows finding the optimum for the power factor in PEDOT-Tos thin films. PMID:27019715

  8. Somatostatin receptor-mediated tumor-targeting drug delivery using octreotide-PEG-deoxycholic acid conjugate-modified N-deoxycholic acid-O, N-hydroxyethylation chitosan micelles.


    Huo, Meirong; Zou, Aifeng; Yao, Chengli; Zhang, Yong; Zhou, Jianping; Wang, Jing; Zhu, Qinnv; Li, Jing; Zhang, Qiang


    In this study, a ligand-PEG-lipid conjugate, octreotide-polyethene glycol-deoxycholic acid (OCT(Phe)-PEG-DOCA, or OPD) was successfully synthesized and used as a targeting molecule for N-deoxycholic acid-O, N-hydroxyethylation chitosan (DAHC) micelles for efficient cancer therapy. DAHC micelles exhibited good loading capacities for doxorubicin (DOX), a model anti-cancer drug, and the modification of OPD showed no significant effect on drug load while slightly increasing the particle size and partly shielding the positive charges on the surface of micelles. Accelerated release rate of DOX from micelles were also observed after OPD modification and the release profile exhibited pH-sensitive properties. Compared with DAHC-DOX micelles, OPD-DAHC-DOX micelles exhibited significantly stronger cytotoxicity to MCF-7 cells (SSTRs overexpression) but with hardly any difference from WI-38 cells (no SSTRs expression). The results of flow cytometry and confocal laser scanning microscopy further revealed that OPD-DAHC-DOX micelles could be selectively taken into tumor cells by SSTRs-mediated endocytosis. In vivo investigation of micelles on nude mice bearing MCF-7 cancer xenografts confirmed that OPD-DAHC micelles possessed much higher tumor-targeting capacity than the DAHC control and exhibited enhanced anti-tumor efficacy and decreased systemic toxicity. These results suggest that OPD-DAHC micelles might be a promising anti-cancer drug delivery carrier for targeted cancer therapy.

  9. μ-η2:η2-Peroxido-bis­[nitratodioxido­bis(pyrrolidin-2-one)uranium(VI)

    PubMed Central

    Takao, Koichiro; Ikeda, Yasuhisa


    In the crystal structure of the title compound, [U2(NO3)2O4(O2)(C4H7NO)4], two UO2 2+ ions are connected by a μ-η2:η2-O2 unit. The O2 unit shows ‘side-on’ coordination to both U atoms. An inversion center is located at the midpoint of the O—O bond in the O2 unit, affording a centrosymmetrically expanded dimeric structure. The U—O(axial) bond lengths are 1.777 (4) Å and 1.784 (4) Å, indicating that the oxidation state of U is exclusively 6+, i.e., UO2 2+. Furthermore, the O—O distance is 1.492 (8) Å, which is typical of peroxide, O2 2–. The U atom is eight-coordinated in a hexa­gonal-bipyramidal geometry. The coordinating atoms of the nitrate and pyrrolidine-2-one ligands and the μ-η2:η2-O2 2– unit are located in the equatorial plane and form an irregular hexa­gon. An inter­molecular hydrogen bond is found between N—H of the pyrrolidine-2-one ligand and the coordinating O of the same ligand in a neighboring complex. A second inter­molecular hydrogen bond is found between the N—H of the other pyrrolidine-2-one ligand and one of the uranyl oxido atoms. PMID:21579030

  10. Acido, ergo sum: Holger Hydén--the neuroscientist in Cortázar's Hopscotch.


    Delgado, Guillermo; Estañol, Bruno


    The fictional Italian author Morelli is throughout the novel "Hopscotch" (1963) Julio Cortázar's alter ego. This character proposes an unoriginal literary hypothesis in chapter 62. There is an allusion to a particular Swedish that 'is working on a chemical theory of thought.' The Swedish neuroscientist under analysis is Holger Hydén (1917-2000), by then professor and chairman of the Department of Histology at the University of Göteborg. Hydén, who was the first to work in neurobiological micromethods, is mentioned by Morelli due to his participation in a symposium held at the end of January 1961, in San Francisco. His pioneering work will never be completely forgotten, because Hydén's neuroscientific legacy lives and will live in Cortázar's "Hopscotch".

  11. Tris(1,10-phenanthroline-κ2 N,N′)nickel(II) hexa­oxido-μ-peroxido-disulfate­(VI) N,N-dimethyl­formamide disolvate monohydrate

    PubMed Central

    Harvey, Miguel Angel; Suarez, Sebastián; Doctorovich, Fabio; Baggio, Ricardo


    The asymmetric unit of the title complex, [Ni(C12H8N2)3]S2O8·2C3H7NO·H2O, consists of a complex [Ni(phen)3]2+ cation and one isolated pds anion, with two DMF mol­ecules and one water mol­ecule as solvates (where phen is 1,10-phenanthroline, pds is the hexa­oxido-μ-peroxoido-di­sulf­ate dianion and DMF is dimethyl­formamide). The [Ni(phen)3]2+ cation is regular, with an almost ideal NiII bond-valence sum of 2.07 v.u. The group, as well as the water solvent mol­ecule, are well behaved in terms of crystallographic order, but the remaining three mol­ecules in the structure display different kinds of disorder, viz. the two DMF mol­ecules mimic a twofold splitting and the pds anion has both S atoms clamped at well-determined positions but with a not-too-well-defined central part. These peculiar behaviours are a consequence of the hydrogen-bonding inter­actions: the outermost SO3 parts of the pds anion are heavily connected to the complex cations via C—H⋯O hydrogen bonding, generating an [Ni(phen)3]pds network and providing for the stability of the terminal pds sites. Also, the water solvent mol­ecule is strongly bound to the structure (being a donor of two strong bonds and an acceptor of one) and is accordingly perfectly ordered. The peroxide O atoms in the pds middle region, instead, appear as much less restrained into their sites, which may explain their tendency to disorder. The cation–anion network leaves large embedded holes, amounting to about 28% of the total crystal volume, which are occupied by the DMF mol­ecules. The latter are weakly inter­acting with the rest of the structure, which renders them much more labile and, accordingly, prone to disorder. PMID:23476355

  12. Crystal structure of μ-peroxido-κ(4) O (1),O (2):O (1'),O (2')-bis-[(nitrato-κO)(2,2':6',2''-terpyridine-κ(3) N,N',N'')dioxidouranium(VI)].


    Kawasaki, Takeshi; Kitazawa, Takafumi


    In the title dimeric complex, [{UO2(NO3)(C15H11N3)}2O2], a peroxide ion bridges the two uran-yl(VI) [O=U=O](2+) ions. The O-O bond length of the peroxide is 1.485 (6) Å and the mid-point of this bond is located at the inversion centre of the dimer. The U atom exhibits a distorted hexa-gonal-bipyramidal coordination geometry with two uran-yl(VI) O atoms occupying the axial positions and one O atom of the monodentate nitrate ion, both O atoms of the peroxide ion and the three N atoms of the chelating tridentate 2,2':6',2''-terpyridine (terpy) ligand in the equatorial positions. Two of the N atoms of the terpy ligand lie above and below the mean plane containing the equatorial ligand atoms and the U atom [deviations from the mean plane: maximum 0.500 (2), minimum -0.472 (2) and r.m.s. = 0.2910 Å]. The dihedral angle between the terpy ligand and the mean plane is 35.61 (7)°. The bond lengths around the U atom decrease in the order U-N > U-Onitrate > U-Operoxo > U=O. The dimeric complexes pack in a three-dimensional network held together by weak π-π inter-actions [centroid-centroid distance = 3.659 (3) Å] between pyridyl rings of the terpy ligands in neighbouring dimers, together with inter-molecular C-H⋯O and C-H⋯π inter-actions. Weak intra-molecular C-H⋯O inter-actions are also observed.

  13. Acid—base behavior of aluminum and silicon oxides — a combination of two approaches: XPS and Lewis acido-basicity; rest potential and Brönsted acido-basicity

    NASA Astrophysics Data System (ADS)

    Casamassima, M.; Darque-Ceretti, E.; Etcheberry, A.; Aucouturier, M.


    In the frame of an investigation on adhesion phenomena between elastomers and oxide substrates, X-ray photoelectron spectroscopy (XPS) and rest electrochemical potential measurements have been used in order to attempt a characterization of the reactivity of various oxides. The first step of the study is a definition of donor/acceptor properties for a solid surface in an interactive model such as the Lewis one. In this case, the Fermi level is an appropriate parameter. An experimental approach is developed to estimate this parameter through photoelectronical data obtained by XPS. As proposed by Mullins and Averbach in 1988 in the case of Al and Si oxides, XPS allows an estimation of the Fermi energy EF, defined as the energy difference between the Fermi level and the upper occupied valence band. A classification of EF values is obtained for different samples of aluminum and silicon oxides; the donor (acceptor) behavior increases for decreasing (increasing) EF. The second step is the validation of the EF classification obtained by XPS. A potentiometric method is used to estimate the rest potential Eo in aqueous solution. The relationship between the Eo and the solution pH is a Nernst law for a large range of pH values, which means that the system is governed by acid-base interactions in Brönsted definition in the interfacial area. When the nature of the oxide substrate is modified, the translation of the Eo versus pH line can be correlated with the EF classification obtained previously. This confirms the relationship already reported between point of zero charge and EF. It can also be considered as a validation of the idea that XPS allows the classification of EF values for those oxides.

  14. Effects of acido-basic support properties on the catalytic hydrogenation of acetylene on gold nano-particles

    NASA Astrophysics Data System (ADS)

    Manda, Abdullah Ahmed

    Metallic gold nanoparticles supported on gamma-Al2O 3 and magnesia-alumina mixed oxide, with different magnesia content have been prepared by sol-gel method and characterized by different techniques (inductive coupled plasma-mass spectroscopy (ICP-MS), XRD, BET surface area analysis, transmission electron microscopy (TEM), CO2 and NH 3 temperature programmed desorption (TPD), H2 temperature programmed reduction (TPR) and FTIR of adsorbed CO2). Such systems were found to produce catalysts with controllable acidity, varying from catalyst possessing large density of acidic and low density of basic sites, others with acidic and basic sites of equal strength and density, and others with large basic and low acid sites densities, respectively. The catalytic assessment of the generated acidity was carried out using 2-propanol decomposition as a test reaction. The results obtained indicate that the presence of magnesia and reduced gold nanopartilces has imparted the catalysts, 1%Au/4%Mg-Al 2O3 and 1%Au/8%Mg-Al2O3, with significant base-catalytic properties. Acetylene hydrogenation and formation of coke deposits were investigated on a gold catalyst supported on gamma-Al2O3 and gold supported on alumina-magnisia mixed oxide with different gold content; 1%Au/gamma-Al 2O3, 1%Au/15%Mg-Al2O3, 2%Au/15%Mg-Al 2O3 and 4%Au/15%Mg-Al2O3. The effect of the H2/C2H2 ratio was studied over a range of values. The catalytic activity and selectivity towards ethylene and other products were investigated at different reaction temperatures. Acetylene hydrogenation was investigated in the presence and absence of ethylene in stream. It is investigated that the adsorption of the triple bond is preferred over the double bond and during selective catalytic (SCR) of C2H2 the two hydrocarbons do not compete for the same adsorption sites. The deactivation of catalysts was studied by temperature programmed oxidation (TPO). Higher content of coke over 1%Au/Al2O3 catalyst was investigated in contrast to the other catalysts in which the basisity of magnesia-alumina supports could have played an important role in inhibiting the acidic carbon formation by possessing smaller number and/or weaker acid sites.

  15. Crystal Structure of ATVORF273, a New Fold for a Thermo- and Acido-Stable Protein from the Acidianus Two-Tailed Virus

    PubMed Central

    Felisberto-Rodrigues, Catarina; Blangy, Stéphanie; Goulet, Adeline; Vestergaard, Gisle; Cambillau, Christian; Garrett, Roger A.; Ortiz-Lombardía, Miguel


    Acidianus two-tailed virus (ATV) infects crenarchaea of the genus Acidianus living in terrestrial thermal springs at extremely high temperatures and low pH. ATV is a member of the Bicaudaviridae virus family and undergoes extra-cellular development of two tails, a process that is unique in the viral world. To understand this intriguing phenomenon, we have undertaken structural studies of ATV virion proteins and here we present the crystal structure of one of these proteins, ATV. ATV forms tetramers in solution and a molecular envelope is provided for the tetramer, computed from small-angle X-ray scattering (SAXS) data. The crystal structure has properties typical of hyperthermostable proteins, including a relatively high number of salt bridges. However, the protein also exhibits flexible loops and surface pockets. Remarkably, ATV displays a new protein fold, consistent with the absence of homologues of this protein in public sequence databases. PMID:23056221

  16. Crystal structure of μ-peroxido-κ4 O 1,O 2:O 1′,O 2′-bis­[(nitrato-κO)(2,2′:6′,2′′-terpyridine-κ3 N,N′,N′′)dioxidouranium(VI)

    PubMed Central

    Kawasaki, Takeshi; Kitazawa, Takafumi


    In the title dimeric complex, [{UO2(NO3)(C15H11N3)}2O2], a peroxide ion bridges the two uran­yl(VI) [O=U=O]2+ ions. The O—O bond length of the peroxide is 1.485 (6) Å and the mid-point of this bond is located at the inversion centre of the dimer. The U atom exhibits a distorted hexa­gonal–bipyramidal coordination geometry with two uran­yl(VI) O atoms occupying the axial positions and one O atom of the monodentate nitrate ion, both O atoms of the peroxide ion and the three N atoms of the chelating tridentate 2,2′:6′,2′′-terpyridine (terpy) ligand in the equatorial positions. Two of the N atoms of the terpy ligand lie above and below the mean plane containing the equatorial ligand atoms and the U atom [deviations from the mean plane: maximum 0.500 (2), minimum −0.472 (2) and r.m.s. = 0.2910 Å]. The dihedral angle between the terpy ligand and the mean plane is 35.61 (7)°. The bond lengths around the U atom decrease in the order U—N > U—Onitrate > U—Operoxo > U=O. The dimeric complexes pack in a three-dimensional network held together by weak π–π inter­actions [centroid–centroid distance = 3.659 (3) Å] between pyridyl rings of the terpy ligands in neighbouring dimers, together with inter­molecular C—H⋯O and C—H⋯π inter­actions. Weak intra­molecular C—H⋯O inter­actions are also observed. PMID:25995895

  17. The Role(s) of Heparan Sulfate Proteoglycan(s) in the wnt-1 Signaling Pathway

    DTIC Science & Technology


    and invertebrates , and are initiated by formation of a polysaccharide chain consisting of (D-glucuronic acido....N-acetyl-D- glucosamine...M.C. Ellis, T.B. Kornberg, and C.S. Goodman. 1989. Expression of Engrailed protein in arthropods, annelids and chordates . Cell 58: 955-968. Patel N.H

  18. Archaebakterien und Phylogenie der Organismen

    NASA Astrophysics Data System (ADS)

    Kandler, Otto


    The determination of the sequence similarity of the ribosomal 16 S RNA of many bacteria and a few higher organisms has shown that the methanogenic, halophilic, and acido-thermophilic organisms are phylogenetically separated from the kingdoms of the Eubacteria and Eukaryotes thus representing a third kingdom called “Archaebacteria”. Many biochemical and molecular biological features support this conclusion.

  19. Efficacy and safety of alendronic acid in the treatment of osteoporosis in children.


    Martín Siguero, Alberto; Áreas Del Águila, Vera Lucía; Franco Sereno, María Teresa; Fernández Marchante, Ana Isabel; Pérez Serrano, Raúl; Encinas Barrios, Carmen


    Objetivos: describir la efectividad y seguridad del uso de acido alendronico en el tratamiento de la osteoporosis en ninos y adolescentes, en condiciones distintas a las autorizadas en la ficha tecnica. Métodos: estudio retrospectivo (2008-2014) de todos los pacientes menores de 18 anos a los que se dispenso acido alendronico para esta indicacion. Los criterios para iniciar tratamiento fueron: densidad mineral osea con puntuacion Z-score ≤ -2,5 DE, antecedentes de fracturas oseas sin traumatismo previo y dolor persistente. Las variables recogidas fueron: demograficas, de tratamiento, clinicas y de seguridad. Se considero efectividad del tratamiento al aumento de la densidad mineral osea hasta obtener Z-score > -2,5 DE. Resultados: un total de 12 pacientes, 8 varones, con una media de edad de 11 anos (} 3 DE), fueron tratados con acido alendronico. Tras un tiempo medio de tratamiento de 2,15 anos (} 1,2 DE), se produjo aumento de la densidad mineral osea en todos los pacientes, 9 de los cuales obtuvieron Z-score > -2,5 DE, por lo que el farmaco se considero efectivo en el 75% de los casos. Ningun paciente presento fracturas oseas ni manifesto efectos adversos durante el tratamiento. Conclusiones: el acido alendronico incremento la densidad mineral osea y se tolero bien en todos los pacientes, por lo que se podria considerar como opcion terapeutica en el tratamiento de la osteoporosis infantil.

  20. Inhibition of fructan-fermenting equine fecal bacteria and Streptococcus bovis by hops (Humulus lupulus L.) ß-acid

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aims: The goals were to determine if the '-acid from hops (Humulus lupulus L.) could be used to control fructan fermentation by equine hindgut microorganisms, and to verify the antimicrobial mode of action on the Streptococcus bovis, which has been implicated in fructan fermentation, hindgut acidos...

  1. Amino alcohol-derived reduced Schiff base V(IV)O and V(V) compounds as catalysts for asymmetric sulfoxidation of thioanisole with hydrogen peroxide.


    Adão, Pedro; Kuznetsov, Maxim L; Barroso, Sónia; Martins, Ana M; Avecilla, F; Costa Pessoa, João


    We report the synthesis and characterization of several amino alcohol-derived reduced Schiff base ligands (AORSB) and the corresponding V(IV)O and V(V) complexes. Some of the related Schiff base variants (amino alcohol derived Schiff base = AOSB) were also prepared and characterized. With some exceptions, all compounds are formulated as dinuclear compounds {V(IV)O(L)}(2) in the solid state. Suitable crystals for X-ray diffraction were obtained for two of the AORSB compounds, as well as a rare X-ray structure of a chiral V(IV)O compound, which revealed a dinuclear {V(IV)O(AOSB)}(2) structure with a rather short V-V distance of 3.053(9) Å. Electron paramagnetic resonance (EPR), (51)V NMR, and density functional theory (DFT) studies were carried out to identify the intervenient species prior to and during catalytic reactions. The quantum-chemical DFT calculations were important to determine the more stable isomers in solution, to explain the EPR data, and to assign the (51)V NMR chemical shifts. The V(AORSB) and V(AOSB) complexes were tested as catalysts in the oxidation of thioanisole, with H(2)O(2) as the oxidant in organic solvents. In general, high conversions of sulfoxide were obtained. The V(AOSB) systems exhibited greater activity and enantioselectivity than their V(AORSB) counterparts. Computational and spectroscopic studies were carried out to assist in the understanding of the mechanistic aspects and the reasons behind such marked differences in activity and enantioselectivity. The quantum-chemical calculations are consistent with experimental data in the assessment of the differences in catalytic activity between V(AOSB) and V(AORSB) peroxido variants because the V(AORSB) peroxido transition states correspond to ca. 22 kJ/mol higher energy activation barriers than their V(AOSB) counterparts.



    Rubi Vargas, María; González Lomelí, Daniel; Terrazas Medina, Efraín A; Peralta Peña, Sandra L; Jordán Jinez, Ma Lourdes; Ruiz Paloalto, Ma Laura; Cupul Uicab, Lea A


    Introducción: estudios recientes sugieren que los niveles bajos de acidos grasos poliinsaturados omega-3 se relacionan con una mayor prevalencia de depresion; sin embargo, los resultados no son concluyentes. Objetivo: evaluar la asociacion entre el bajo consumo de acidos grasos omega-3 y la presencia de sintomas depresivos en jovenes universitarios del noroeste de Mexico. Métodos: se realizo un estudio transversal en una muestra de 706 universitarios de 18 a 24 anos de edad de ambos sexos. La presencia de sintomatologia depresiva se estimo con la escala de Depresion del Centro de Estudios Epidemiologicos (CES-D) empleando un punto de corte ≥ 24. El consumo semanal de acidos grasos alfalinolenico (ALA) y de eicosapentaenoico (EPA) mas docosahexaenoico (DHA) en mg/g de alimento se estimo por medio de un cuestionario de frecuencia de consumo de alimentos validado para la poblacion mexicana. La asociacion del consumo de omega-3 con la presencia de sintomas depresivos se evaluo con modelos de regresion logistica. Resultados: el 67% de los participantes fueron mujeres; en general, el 16,6% presentaron sintomatologia depresiva. El consumo bajo de ALA y EPA + DHA no se asocio con mayor prevalencia de sintomatologia depresiva antes y despues de ajustar por confusores. En aquellos casos con sintomatologia depresiva, los niveles ALA derivados solo de las nueces fueron significativamente menores. Conclusiones: en esta poblacion no se observo asociacion entre el bajo consumo de acidos grasos omega-3 y la sintomatologia depresiva. La posible asociacion entre el consumo de nueces y la sintomatologia depresiva requiere de mas estudios.

  3. [Hypomyelination with atrophy of the basal ganglia and cerebellum. Contribution of two new cases to a recently reported entity].


    Tomás-Vila, Miguel; Menor, Francisco; Ley-Martos, Myriam; Jumillas-Luján, M José; Marco-Hernández, Ana V; Barbero, Pedro


    Introduccion. La hipomielinizacion con atrofia de ganglios basales y de cerebelo (H-ABC) es una rara entidad descrita recientemente. Se presentan dos nuevos casos pertenecientes a una misma familia. Casos clinicos. Caso 1: niño de 17 meses con retraso grave en todas las areas, ausencia de lenguaje y de contacto visual. En la exploracion destacaba una microcefalia con tetraparesia espastica. En la resonancia magnetica cerebral se apreciaba atrofia cerebelosa de predominio vermiano con perdida de volumen de ambos nucleos del putamen y la cabeza del caudado, y patron de hipomielinizacion de la sustancia blanca. En la electromiografia se objetivo un patron de polineuropatia cronica de predominio motor. Presento un descenso de los valores de acido homovalinico y de acido 5-hidroxindolacetico. El tratamiento con levodopa/carbidopa no fue efectivo. Caso 2: niña de 11 meses, hermana del caso anterior. Presentaba un retraso grave en todas las areas y en la exploracion clinica se detecto una microcefalia con tetraparesia espastica. La resonancia magnetica cerebral mostro hallazgos superponibles a los del hermano, con hipomielinizacion, atrofia cerebelosa y afectacion putaminal y de ambos caudados; en la electromiografia, hallazgos compatibles con polineuropatia motora de caracter desmielinizante. Presento un descenso de los valores de acido homovalinico y acido 5-hidroxindolacetico en el liquido cefalorraquideo. El tratamiento con levodopa/carbidopa resulto ineficaz. Conclusiones. Estos dos nuevos casos ayudan a caracterizar mejor esta entidad y refuerzan la hipotesis del origen genetico del sindrome, dado que se trata de dos casos pertenecientes a una misma familia.

  4. DoD Electronic Data Interchange (EDI) Convention: ASC X12 Transaction Set 805 Contract Pricing Proposal (Version 003030)

    DTIC Science & Technology


    ASD(P&L)] memorandum of November 21, 1989, Subject: Production and Logistics Task Group for Data Protection. Publication of these conventions is based ...Mandatory Mandatory data elements are defined by ASC X12. Optional Optional data elements are used at the discretion of the sending party or are based upon...1993 is 545.00. It is a (Daft .aimuemme acido . has beo subhmitted to niapdowati e (-secode Al). add PKDDS [data debmot PDD1-48.00-All al Indicate doe

  5. Coagulopathy by Hypothermia and Acidosis: Mechanisms of Thrombin Generation and Fibrinogen Availability

    DTIC Science & Technology


    models in swines are based on concepts and procedures developed previously in other animals, particularly the dog; yet, they are superior to canine...degradation via different mech- anisms. Despite the differential effects, hypothermia and acido - sis lead to a consistent outcome: deficit in...hypothermia and acidoses revisited. J Trauma. 1997;42:857–861; discussion 861–862. 4. Ferrara A, MacArthur JD, Wright HK, Modlin IM, McMillen MA. Hypothermia

  6. [Use of fish oil lipid emulsions in hospitalized patients under 18 years old with abnormal results in liver tests associated with total parental nutrition].


    Giraldo Villa, Adriana; Henao Roldan, Catherine; García Loboguerrero, Fanny; Martínez Volkmar, María Isabel; Contreras Ramírez, Mónica María; Ruiz Navas, Patricia


    Introducción: La Nutricion Parental Total (NPT) prolongada esta asociada con complicaciones potencialmente mortales en la poblacion pediatrica como lo es la colestasis. Dentro del soporte nutricional, la fuente de acidos grasos, el contenido de fitoesteroles y la dosis de lipidos se han relacionado con el desarrollo de esta complicacion. Objetivo: Describir el comportamiento de las pruebas hepaticas en pacientes pediatricos con NPT en quienes se uso lipidos a base de acidos grasos omega 3 (omegavenR). Métodos: Estudio retrospectivo, en menores de 18 anos con tratamiento intravenoso por minimo 8 dias con acidos grasos omega 3. Los pacientes fueron inicialmente clasificados en dos grupos: colestasis y alteracion de pruebas hepaticas. Se evaluo el comportamiento de la transaminasa glutamico oxalacetica (TGO), transaminasa glutamico piruvica (TGP), bilirrubina total (BT), bilirrubina directa, gama glutamil transferasa (GGT) y fosfatasa alcalina (FA) antes y despues del tratamiento con omegaven R. Resultados: 33 pacientes cumplieron los criterios de inclusion. Al finalizar la administracion de omegavenR, 82,4% de los pacientes que presentaron inicialmente colestasis mostraron resolucion o mejoria. En el grupo de pacientes con alteracion de pruebas hepaticas 18,8% progresaron a colestasis. Conclusiones: Nuestro estudio sugiere que el uso de omegaven R en pacientes pediatricos con NPT y BD ≥ 2 mg/dL, parece revertir o mejorar la colestasis, mientras que en pacientes con alteracion de pruebas hepaticas aun no se tiene claro su efecto.

  7. [Status epilepticus in paediatrics: a retrospective study and review of the literature].


    Moreno-Medinilla, Esther E; Negrillo-Ruano, Rocío; Calvo-Medina, Rocío; Mora-Ramírez, M Dolores; Martínez-Antón, Jacinto L


    Introduccion. El estado epileptico (EE) es la emergencia neurologica mas frecuente en pediatria. Dada la posibilidad de secuelas neurologicas y mortalidad asociadas, requiere un tratamiento agresivo precoz. Pacientes y metodos. Estudio descriptivo retrospectivo a traves de la revision de historias clinicas de pacientes ingresados en nuestro hospital entre 2010-2013 con diagnostico de EE. El objetivo fue describir las caracteristicas epidemiologicas y el manejo de estos pacientes, asi como revisar la bibliografia disponible sobre este tema. Resultados. Hemos recogido 39 pacientes (25 varones) y 51 episodios de EE. Edad media: 4,8 años. Tenian enfermedad de base 22 pacientes. Dieciocho eran epilepticos conocidos y cinco tuvieron un EE previo. De los 51 episodios de EE, 33 fueron sintomaticos, 15 febriles y tres criptogenicos. Los tipos de EE fueron: 25 parciales (de ellos, 16 complejos) y 26 generalizados. El tratamiento de primera eleccion fue benzodiacepinas en 47 pacientes (40, diacepam), fenitoina en tres y acido valproico en uno. Veintisiete pacientes precisaron farmacos de segunda linea: 16, acido valproico; ocho, fenitoina; dos, fenobarbital; y uno, levetiracetam. Diez pacientes precisaron farmacos de tercera linea para la induccion del coma: el midazolam fue el mas utilizado en nuestro centro, seguido del tiopental y el propofol. Dos EE superrefractarios requirieron inmunoglobulinas y corticoides sistemicos por presentarse en el curso de encefalitis autoinmunes. Conclusiones. Debe plantearse el esquema terapeutico del EE desde el inicio de cualquier crisis convulsiva. El tratamiento es escalonado, con benzodiacepinas en la primera etapa, antiepilepticos de amplio espectro y disponibilidad intravenosa en la segunda (acido valproico, levetiracetam en el EE generalizado y fenitoina en el EE focal), mientras que el tercer nivel varia en funcion de la experiencia de cada equipo.

  8. [Simultaneous pulmonar, laryngeal and lingual affectation by Mycobacterium tuberculosis].


    Díaz Manzano, J A; Castillo Romero, J L; Padilla Romero, M J; Sánchez Laínez, J J; Castillo Aguilar, C; Cegarra Navarro, M F


    The incidence of tuberculosis has lately increased in developed countries. The most frequent affectation is the pulmonar one and in the ORL area the laryngeal. The lingual affectation is exceptional. We present a case of a man 39 years old, with bilateral pulmonar, left vocal cord and mobile tongue affectation, negative Mantoux, positive spit culture and presence of acido-alcohol resistent bacillus in lingual and laryngeal biopsies. After antituberculosis treatment during 6 months the laryngeal and lingual lesions disappeared. We have only found two cases published of simultaneous tuberculosis in these three localisations in the last 30 years.

  9. [Aetiology and treatment of epilepsy in a series of 1,557 patients].


    Torres-Ferrús, Marta; Toledo, Manuel; González-Cuevas, Montserrat; Seró-Ballesteros, Laia; Santamarina, Esteban; Raspall-Chaure, Miquel; Sueiras-Gil, María; Cambrodí-Masip, Roser; Sarria, Silvana; Álvarez-Sabín, José; Salas-Puig, Javier


    Introduccion. La etiologia de la epilepsia es un determinante importante del tratamiento y el pronostico. Los avances diagnosticos y terapeuticos hacen pensar que la distribucion causal, el tratamiento y el pronostico de la poblacion con epilepsia se hayan podido ver modificados. Objetivo. Describir la distribucion sindromica, etiologica y el tratamiento farmacologico en los pacientes con epilepsia. Pacientes y metodos. Estudio descriptivo transversal de pacientes con epilepsia atendidos de manera consecutiva en la consulta de nuestra unidad de epilepsia. Se recogieron datos demograficos, de sindrome, etiologia y tratamiento farmacologico en el momento de la inclusion. Se analizaron los datos de modo conjunto y por grupos de edad. Resultados. Se incluyeron 1.557 pacientes, el 54% varones. El 73% de la muestra tenia una epilepsia focal, que era secundaria a una lesion estructural en el 56%. Las epilepsias generalizadas representaron el 20%. El 5% fue inclasificable. Por edad, la etiologia vascular predominaba en practicamente todos los grupos y su prevalencia aumentaba en relacion con la edad. Los farmacos antiepilepticos mas utilizados fueron acido valproico (29%), levetiracetam (27%) y carbamacepina (20%). El 70% de las epilepsias generalizadas y el 57% de las focales seguian tratamiento en monoterapia. Conclusiones. La prevalencia por grupos de edad fue similar a la descrita en paises desarrollados aunque se observo una menor prevalencia de epilepsias criptogenicas. Mas del 60% de los pacientes seguia monoterapia y el acido valproico fue el mas utilizado.

  10. First principle study of the surface reactivity of layered lithium oxides LiMO2 (M = Ni, Mn, Co)

    NASA Astrophysics Data System (ADS)

    Vallverdu, Germain; Minvielle, Marie; Andreu, Nathalie; Gonbeau, Danielle; Baraille, Isabelle


    LiNixMnyCo1 - x - yO2 compounds (NMC) are layered oxides widely used in commercial lithium-ion batteries at the positive electrode. Nevertheless surface reactivity of this material is still not well known. As a first step, based on first principle calculations, this study deals with the electronic properties and the surface reactivity of LiMO2 (M = Co, Ni, Mn) compounds, considering the behavior of each transition metal separately in the same R 3 ̅ mα-NaFeO2-type structure, the one of LiCoO2 and NMC. For each compound, after a brief description of the bare slab electronic properties, we explored the acido-basic and redox properties of the (110) and (104) surfaces by considering the adsorption of a gaseous probe. The chemisorption of SO2 produces both sulfite or sulfate species associated respectively to an acido-basic or a reduction process. These processes are localized on the transition metals of the first two layers of the surface. Although sulfate species are globally favored, a different behavior is obtained depending on both the surface and the transition metal considered. We conclude with a simple scheme which describes the reduction processes on the both surfaces in terms of formal oxidation degrees of transition metals.

  11. Study of the chemical mechanisms of the reaction of neutralization of calcium hydroxide by phosphoric acid

    NASA Astrophysics Data System (ADS)

    Elgadi, M.; Mejdoubi, E.; Elansari, L. L.; Essaddek, A.; Abouricha, S.; Lamhamdi, A.


    Calcium phosphates reported in this study, are prepared following an acido-basic reaction between phosphoric acid and calcium hydroxide. These phosphates are the brushite, tricalcium phosphate, hydroxyapatite and oxygenated apatite. The follow-up of the reaction by infra-red spectroscopy of absorption showed that the alkaline pH of calcium hydroxide solution, favours the formation of carbonated apatite, at the start of the reaction. Following the addition of phosphoric acid, the pH becomes increasingly favourable to the formation of the desired phase. The insertion of molecular oxygen in the apatitic tunnel is carried out by the use of hydrogen peroxide. The molecular oxygen rate in the apatite is then determined by volumetric analysis.

  12. Synthesis, Kinetics, and Photochemistry of the Chromium(III) DicyanoaquoEDTA Complex.

    DTIC Science & Technology


    carboxyl groups unattached, and protonated. Later, Hamn4 studied the acid- base equilibrium Cr(YH)(H 20) - Cr(Y)(H20)’. That the water in Cr(YH)(H 20...Thorneley et I’ 6 in an extensive study of acid- base and related equilibria, were unable to find evidence for the CrY" species. The EDTA complexes of...5) CrY)H(Ho2- 2- + Cr(Y)C(OH)(H 0) r(Y)(OH)2 + H pK -8.0 (Ref. 5) (6) Also, Cr(Y)(OH) + H20 - Cr(Y)(OH)" + H Pa 12.2 (Ref. 7) (7). Di- acido

  13. Group-specific PCR primers for the phylum Acidobacteria designed based on the comparative analysis of 16S rRNA gene sequences.


    Lee, Sang-Hoon; Cho, Jae-Chang


    We performed a comprehensive phylogenetic analysis of the phylum Acidobacteria and developed novel, group-specific PCR primers for Acidobacteria and its class-level subgroups. Acidobacterial 16S rRNA gene sequences deposited in the RDP database were used to construct a local database then subsequently analyzed. A total of 556 phylotypes were observed and the majority of the phylotypes belonged to five major subgroups (subgroups 1, 2, 3, 4, and 6), which comprised >80% of the acidobacterial sequences in the RDP database. Phylum-specific and subgroup-specific primers were designed from the consensus sequences of the phylotype sequences, and the specificities of the designed primers were evaluated both in silico and empirically for coverage and tolerance. The phylum-specific primer ACIDO, which was designed in this study, showed increased coverage for Acidobacteria, as compared to the previous phylum-specific primer 31F. However, the tolerance of the primer ACIDO for non-target sequences was slightly higher than that of the primer 31F. We also developed subgroup-specific PCR primers for the major subgroups of Acidobacteria, except for subgroup 4. Subgroup-specific primers S1, S2, and S3, which targeted subgroups 1, 2, and 3, respectively, showed high coverage for their target subgroups and low tolerance for non-target sequences. However, the primer S6 targeting subgroup 6 showed a lower specificity in its empirical evaluation than expected from the in silico results. The subgroup-specific primers, as well as the phylum-specific primer designed in this study, will be valuable tools in understanding the phylogenetic diversity and ecological niche of the phylum Acidobacteria and its subgroups.

  14. Binding of oxime group to uranyl ion.


    Tsantis, Sokratis T; Zagoraiou, Eirini; Savvidou, Aikaterini; Raptopoulou, Catherine P; Psycharis, Vassilis; Szyrwiel, Lukasz; Hołyńska, Małgorzata; Perlepes, Spyros P


    Currently, the leading approach for extraction of uranium from seawater is selective sorption of UO2(2+) ions onto a poly(acrylamidoxime) fiber. Amidoxime functional groups are the most studied extractant moieties for this application, but are not perfectly selective, and understanding how these groups (and more generally the oxime groups) interact with UO2(2+) and competing ions in seawater is an important step in designing better extractants. We have started a new research programme aiming at in-depth studies of the uranyl-oxime/amidoxime interactions and we report here our first results which cover aspects of the coordination chemistry of 2-pyridyl ketoximes towards UO2(2+). Detailed synthetic investigations of various UO2(2+)/mepaoH and UO2(2+)/phpaoH reaction systems (mepaoH is methyl 2-pyridyl ketoxime and phpaoH is phenyl 2-pyridyl ketoxime) have provided access to the complexes [UO2(mepao)2(MeOH)2]{[UO2(NO3)(mepao)(MeOH)2]}2 (), [UO2(mepao)2(MeOH)2] (), [(UO2)2(O2)(O2CMe)2(mepaoH)2] () and [UO2(phpao)2(MeOH)2] (). The peroxido group in , which was isolated without the addition of external peroxide sources, probably arises from a bis(aquo)- and/or bis(hydroxido)-bridged diuranyl precursor in solution followed by photochemical oxidation of the bridging groups. The U(VI) atom in the [UO2(NO3)(mepao)(MeOH)2] molecules of () is surrounded by one nitrogen and seven oxygen atoms in a very distorted hexagonal bipyramidal geometry; two oxygen atoms from the terminal MeOH ligands, two oxygen atoms from the bidentate chelating nitrato group, and the oxygen and nitrogen atoms from the η(2) oximate group of the 1.110 (Harris notation) mepao(-) ligand define the equatorial plane. This plane consists of two terminal MeOH ligands and two η(2) oximate groups in the [UO2(mepao)2(MeOH)2] molecule () of . The structure of the [UO2(mepao)2(MeOH)2] molecule that is present in is very similar to the structure of the corresponding molecule in . The structure of the dinuclear

  15. The Mediterranean diet and micronutrient levels in depressive patients.


    Ibarra, Olga; Gili, Margalida; Roca, Miguel; Vives, Margalida; Serrano, María Jesús; Pareja, Antonio; García-Campayo, Javier; Gómez-Juanes, Rocío; García-Toro, Mauro


    Introducción: Se ha comunicado una correlación inversa entre depresión y el nivel sérico de algunos micronutrientes (selenio, zinc, hierro, magnesio, vitamina B y acido fólico). Además, otros estudios han señalado que la suplementar de estos micronutrientes puede mejorar la depresión. La dieta mediterránea proporciona una suficiente cantidad de los micronutrientes mencionados, aunque ningún estudio ha probado si la prescripción de dicha dieta puede incrementar los niveles de micronutrientes en pacientes depresivos. Objetivo: Examinar el impacto de recomendar un patrón dietético mediterráneo en los niveles de micronutrientes de pacientes deprimidos. Material y Métodos: 77 pacientes ambulatorios se aleatorizaron entre un grupo de intervención (recomendaciones higiénico-dietéticas sobre dieta, ejercicio, sueño y exposición solar) y un grupo control. La evolución fue evaluada antes y después de los seis meses del periodo de intervención. Resultados: Los niveles de selenio y de zinc fueron ligeramente bajos en la determinación basal y el nivel de selenio correlacionaba inversamente con la severidad de la depresión (r=-0.233; p=0.041). El grupo activo evolucionó mejor de la clínica depresiva. Sin embargo, no se observaron diferencias significativas en los niveles de micronutrientes después de la prescripción del patrón de dieta mediterránea probablemente a causa de una insuficiente adherencia. Conclusión: Los niveles séricos de selenio, zinc, hierro, magnesio vitamina B12 y acido fólico no aumentaron en pacientes depresivos seis meses después de prescribir un patrón de dieta mediterránea.

  16. Glass transition of adsorbed stereoregular PPMA by inverse gas chromatography at infinite dilution

    NASA Astrophysics Data System (ADS)

    Hamieh, T.; Rezzaki, M.; Grohens, Y.; Schultz, J.


    In this paper, we used inverse gas chromatography (IGC) at infinite dilution that proved to be a powerful technique to determine glass transition and other transitions of PMMA adsorbed on α-alumina. We highlighted the glass transition temperature of the system PMMA/α-Al2O3 with defined polymer tacticity at various covered surface fractions. Thus, the Tg of the adsorbed isotactic PMMA increases strongly as compared to the bulk value. The study of the physical chemical properties of PMMA/α-alumina revealed an important difference in the acidic and basic behaviour, in Lewis terms, of aluminium oxide covered by various concentrations of PMMA. It appears that there is a stabilisation of the physical chemical properties of PMMA/α-Al2O3 for a surface coverage above 50%. This study also highlighted an important effect of the tacticity of the polymer on the acid-base character of the system PMMA/Al2O3. Dans cet article, nous montrons que la chromatographie gazeuse inverse (CGI) à dilution infinie se révèle être une technique très intéressante pour la détermination de la transition vitreuse de polymères stéréoréguliers adsorbés sur des substrats solides tels que l'alumine. Nous avons mis en évidence des transitions attribuées aux phénomènes de relaxation béta, transition vitreuse et autres transitions des systèmes PMMA/Al2O3 de tacticité définie à différents taux de recouvrement. Ainsi, la Tg du PMMA isotactique adsorbé augmente de façon significative par rapport a celle du polymère massique. L'étude des propriétés physico-chimiques du système PMMA/Al2O3, révèle une différence importante dans le comportement acido-basique, au sens de Lewis, de l'alumine pour de taux de recouvrement en PMMA variables. Il apparaît qu'il y a stabilisation des propriétés physico-chimiques de PMMA/Al2O3 pour un taux de recouvrement en PMMA supérieur à 50 %. Cette étude a montré également une influence importante de la tacticité du polymère sur le

  17. Adsorption mechanism of acids and bases in reversed-phase liquid chromatography in weak buffered mobile phases designed for liquid chromatography/mass spectrometry.


    Gritti, Fabrice; Guiochon, Georges


    The overloaded band profiles of five acido-basic compounds were measured, using weakly buffered mobile phases. Low buffer concentrations were selected to provide a better understanding of the band profiles recorded in LC/MS analyses, which are often carried out at low buffer concentrations. In this work, 10 microL samples of a 50 mM probe solution were injected into C(18)-bonded columns using a series of five buffered mobile phases at (SW)pH between 2 and 12. The retention times and the shapes of the bands were analyzed based on thermodynamic arguments. A new adsorption model that takes into account the simultaneous adsorption of the acidic and the basic species onto the endcapped adsorbent, predicts accurately the complex experimental profiles recorded. The adsorption mechanism of acido-basic compounds onto RPLC phases seems to be consistent with the following microscopic model. No matter whether the acid or the base is the neutral or the basic species, the neutral species adsorbs onto a large number of weak adsorption sites (their saturation capacity is several tens g/L and their equilibrium constant of the order of 0.1 L/g). In contrast, the ionic species adsorbs strongly onto fewer active sites (their saturation capacity is about 1g/L and their equilibrium constant of the order of a few L/g). From a microscopic point of view and in agreement with the adsorption isotherm of the compound measured by frontal analysis (FA) and with the results of Monte-Carlo calculations performed by Schure et al., the first type of adsorption sites are most likely located in between C(18)-bonded chains and the second type of adsorption sites are located deeper in contact with the silica surface. The injected concentration (50 mM) was too low to probe the weakest adsorption sites (saturation capacity of a few hundreds g/L with an equilibrium constant of one hundredth of L/g) that are located at the very interface between the C(18)-bonded layer and the bulk phase.

  18. Synthesis, characterization, reactivity and catalytic activity of oxidovanadium(IV), oxidovanadium(V) and dioxidovanadium(V) complexes of benzimidazole modified ligands.


    Maurya, Mannar R; Bisht, Manisha; Kumar, Amit; Kuznetsov, Maxim L; Avecilla, Fernando; Pessoa, João Costa


    The reaction between [V(IV)O(acac)(2)] and the ONN donor Schiff base obtained by the condensation of pyridoxal and 2-aminoethylbenzimidazole (Hpydx-aebmz, I) or 2-aminomethylbenzimidazole (Hpydx-ambmz, II) in equimolar amounts results in the formation of [V(IV)O(acac)(pydx-aebmz)] 1 and [V(IV)O(acac)(pydx-ambmz)] 2, respectively. The aerobic oxidation of the methanolic solution of 1 yielded [V(V)O(2)(pydx-aebmz)] 3 and its reaction with aqueous H(2)O(2) gave the oxidoperoxidovanadium(v) complex, [V(V)O(O(2))(pydx-aebmz)] 4. The formation of 4 in solution is also established by titrations of methanolic solutions of 1 with H(2)O(2). By titrating solutions of 3 and of 4 with aqueous H(2)O(2) several distinct V(V)-pydx-aebmz species also containing the peroxido ligand are detected. The full geometry optimization of all species envisaged was done using DFT methods for suitable model complexes. The (51)V NMR chemical shifts (δ(V)) have also been calculated, the theoretical data being used to support assignments of the experimental chemical shifts. The (51)V hyperfine coupling constants are calculated for 1, the obtained values being in good agreement with the experimental EPR data. Reaction between the V(IV)O(2+) exchanged zeolite-Y and Hpydx-aebmz and Hpydx-ambmz in refluxing methanol, followed by aerial oxidation results in the formation of the encapsulated V(V)O(2)-complexes, abbreviated herein as [V(V)O(2)(pydx-aebmz)]-Y 5 and [V(V)O(2)(pydx-ambmz)]-Y 6. The molecular structure of 1, determined by single crystal X-ray diffraction, confirms its distorted octahedral geometry with the ONN binding mode of the tridentate ligand, with one acetylacetonato group remaining bound to the V(IV)O-centre. Oxidation of styrene is investigated using some of these complexes as catalyst precursors with H(2)O(2) as oxidant. Under optimised reaction conditions for the conversion of styrene in acetonitrile, a maximum of 68% conversion of styrene (with [V(V)O(2)(pydx-aebmz)]-Y) and 65

  19. Survey of several methods deproteinizing human plasma before and within the chloroformate-mediated treatment of amino/carboxylic acids quantitated by gas chromatography.


    Hušek, Petr; Svagera, Zdeněk; Hanzlíková, Dagmar; Simek, Petr


    Trichloroacetic acid, perchloric acid, phosphotungstic acid, acetonitrile, methanol and some other organic solvents were evaluated for their ability to provide protein and lipid-free plasma supernatants. The residual proteins, total cholesterol and triacylglycerols were assayed in the supernatant on a Beckman Analyzer instrument. The free cholesterol and the neutral lipids were further analyzed by means of high-temperature GC analysis. The conditions for the deproteinizing step were optimized for minimal lipoprotein disruption. A substantial difference regarding contamination by the lipids was found if the plasma supernatant or the whole serum were treated with an alkyl chloroformate reagent. Three plasma sulfur amino acids and the aromatic ones were chosen as model compounds to evaluate compatibility of the precipitation methods with a subsequent methyl chloroformate-mediated derivatization and GC-MS analysis. The results of the total homocysteine assay matched well with that obtained using a commercial immunoassay. Precipitation with trichloroacetic acid has proven to be a method of choice for the analysis of the acido-basic analytes by GC-MS via chloroformates.

  20. Features of the hydrosilylation of polyfunctional methylvinyl- and methylhydrosiloxanes

    SciTech Connect

    Kopylov, V.M.; Kovyazine, T.G.; Buslaeva, T.M.; Sinitsyn, N.M.; Kireev, V.V.; Gorshkov, A.V.


    A study of the reactivity of polyfunctional methylvinyl- and methylhydrosiloxanes in the presence of platinum catalysts has shown that the reactivity of the Si-CH=CH/sub 2/ groups is unchanged, but that of the Si-H groups decreases as the extent of reaction of the functional groups increases. Examination of the influence of the type of catalysts, comprising H/sub 2/PtCl/sub 6/ x 6H/sub 2/O and tetraorganoammonium platinum salts, on the reactions of polyfunctional methylvinyl- and methylhydrosiloxanes has shown that the catalytic activity of the salts is lower than that of H/sub 2/PtCl/sub 6/ x 6H/sub 2/O, and varies over a wide range with changes in the organic radical in the tetraorganoammonium cation, the oxidation state of the platinum, and the nature of the acido ligand. In the presence of these tetraorganoammonium platinum salts, addition of silicon hydrides to methylvinylcycloxiloxanes takes place predominantly in the ..beta..-position. The PMR spectra of the addition products were obtained on Bruker WM-90 and WM-250 instruments, operating frequencies 90 and 250 MHz, in CCl/sub 4/ and CDCl/sub 3/, cyclohexane being used as internal standard.

  1. Gas-phase structures and thermochemistry of neutral histidine and its conjugated acid and base.


    Riffet, Vanessa; Bouchoux, Guy


    Extensive exploration of the conformational space of neutral, protonated and deprotonated histidine has been conducted at the G4MP2 level. Theoretical protonation and deprotonation thermochemistry as well as heats of formation of gaseous histidine and its ionized forms have been calculated at the G4 level considering either the most stable conformers or an equilibrium population of conformers at 298 K. These theoretical results were compared to evaluated experimental determinations. Recommended proton affinity and protonation entropy deduced from these comparisons are PA(His) = 980 kJ mol(-1) and ΔpS(His) ∼ 0 J mol(-1) K(-1), thus leading to a gas-phase basicity value of GB(His) = 947.5 kJ mol(-1). Similarly, gas phase acidity parameters are ΔacidH(o)(His) = 1373 kJ mol(-1), ΔacidS(His) ∼ 10 J mol(-1) K(-1) and ΔacidG(o)(His) = 1343 kJ mol(-1). Computed G4 heats of formation values are equal to -290, 265 and -451 kJ mol(-1) for gaseous neutral histidine and its protonated and deprotonated forms, respectively. The present computational data correct, and complete, previous thermochemical parameter estimates proposed for gas-phase histidine and its acido-basic properties.

  2. Noble-metal-based catalysts supported on zeolites and macro-mesoporous metal oxide supports for the total oxidation of volatile organic compounds.


    Barakat, Tarek; Rooke, Joanna C; Tidahy, Haingomalala Lucette; Hosseini, Mahsa; Cousin, Renaud; Lamonier, Jean-François; Giraudon, Jean-Marc; De Weireld, Guy; Su, Bao-Lian; Siffert, Stéphane


    The use of porous materials to eliminate volatile organic compounds (VOCs) has proven very effective towards achieving sustainability and environmental protection goals. The activity of zeolites and macro-mesoporous metal-oxide supports in the total oxidation of VOCs has been investigated, with and without noble-metal deposition, to develop highly active catalyst systems where the formation of by-products was minimal. The first catalysts employed were zeolites, which offered a good activity in the oxidation of VOCs, but were rapidly deactivated by coke deposition. The effects of the acido-basicity and ionic exchange of these zeolites showed that a higher basicity was related to exchanged ions with lower electronegativities, resulting in better catalytic performances in the elimination of VOCs. Following on from this work, noble metals were deposited onto macro-mesoporous metal-oxide supports to form mono and bimetallic catalysts. These were then tested in the oxidation of toluene to study their catalytic performance and their deactivation process. PdAu/TiO(2) and PdAu/TiO(2) -ZrO(2) 80/20 catalysts demonstrated the best activity and life span in the oxidation of toluene and propene and offered the lowest temperatures for a 50 % conversion of VOCs and the lowest coke content after catalytic testing. Different characterization techniques were employed to explain the changes occurring in catalyst structure during the oxidation of toluene and propene.

  3. An environmentally friendly method to remove and utilize the highly toxic strychnine in other products based on proton-transfer complexation

    NASA Astrophysics Data System (ADS)

    Adam, Abdel Majid A.; Refat, Moamen S.; Saad, Hosam A.; Hegab, Mohamed S.


    The study of toxic and carcinogenic substances represents one of the most demanding areas in human safety, due to their repercussions for public health. There is great motivation to remove and utilize these substances in other products instead of leaving them contaminate the environment. One potentially toxic compound for humans is strychnine (Sy). In the present study, we attempted to establish a quick, simple, direct and efficient method to remove and utilize discarded Sy in other products based on proton-transfer complexation. First, Sy was reacted with the acido organic acceptors PA, DNBA and CLA. Then, the resultant salts were direct carbonized into carbon materials. Also, this study provides an insight into the structure and morphology of the obtained products by a range of physicochemical techniques, such as UV-visible, IR, 1H NMR and 13C NMR spectroscopies; XRD; SEM; TEM; and elemental and thermal analyses. Interestingly, the complexation of Sy with the PA or DNBA acceptor leads to a porous carbon material, while its complexation with CLA acceptor forms non-porous carbon product.

  4. Dietary potential renal Acid load in venezuelan children.


    López-Sayers, Mayerling; Bernal, Jennifer; López, Michelle


    Objetivo: Determinar y analizar la carga acida potencial renal de la dieta (Potential Renal Acid Load PRAL) y el patron de alimentacion de ninos entre 1 a 6 anos aparentemente sanos. Métodos: Se seleccionaron segun conveniencia a padres de 52 ninos asistentes a una consulta de ninos sanos. La calidad de la dieta y el patron de alimentacion se evaluo mediante un recordatorio de 24 horas y un cuestionario de frecuencia de alimentos. Se calculo la ingesta de macronutrientes y grupos de alimentos, como carnes, lacteos, frutas y verduras. La ingesta de nutrientes se comparo con las recomendaciones de energia y nutrientes. El PRAL se determino segun el metodo de Remer y Manz, para determinar la carga acida de la dieta. Se aplico estadistica descriptiva y correlaciones entre el PRAL, nutrientes y grupos de alimentos. Resultados: La ingesta de proteinas, de leche y de carnes fue elevada, mientras que la ingesta de rutas y hortalizas fue baja. El PRAL fue positivo en 92% de los ninos, se asocio con mayor ingesta de energia, proteinas, grasas, carne y lacteos. La ingesta de proteinas fue > 2,5 g/kg/ dia en 46,2% de los ninos. Los grupos de alimentos con mayor desequilibrio debido a exceso fueron la carne y los productos lacteos, mientras que por deficit fue el grupo de frutas y hortalizas. Conclusión: La dieta se caracteriza por una elevada carga de acido o PRAL, lo que aumenta el riesgo de acidosis sistemica y sus consecuencias metabolicas.

  5. Operation of the ISO-DALT system: Seventh edition

    SciTech Connect

    Tollaksen, S.L.; Anderson, N.L.; Anderson, N.G.


    The ISO-DALT system of two-dimensional electrophoresis was developed as a series of modifications of the original technique of O'Farrell. We have written a series of recipes and more detailed laboratory procedures that incorporate refinements and ''tricks of the trade'' as they have developed during our use of the system. The present collection is the seventh version in this series and represents the state of art as of May 1984. The seventh edition has been prepared to incorporate the changes that we have found helpful, as well as to add a few new sections such as silver staining, transfer gels, ACIDOs, and BASOs. Although these directions are specific for our laboratory, we hope that they will be helpful in other laboratories as well. Although some disagreement still exists, we recommend that gel patterns be oriented with acid isoelectric points (pIs) to the left and high sodium dodecyl sulfate (SDS) molecular weights at the top. This results in a system of pI and molecular weight values that run according to the Cartesian convention and facilitates the use of the charge and molecular weight standards described herein. 67 refs., 14 figs.

  6. Origin of highly active metal-organic framework catalysts: defects? Defects!


    Canivet, J; Vandichel, M; Farrusseng, D


    This article provides a comprehensive review of the nature of catalytic sites in MOFs. In the last decade, a number of striking studies have reported outstanding catalytic activities of MOFs. In all cases, the authors were intrigued as it was unexpected from the ideal structure. We demonstrate here that (surface) defects are at the origin of the catalytic activities for the reported examples. The vacancy of ligands or linkers systematically generates (surface) terminations which can possibly show Lewis and/or Brønsted acido-basic features. The engineering of catalytic sites at the nodes by the creation of defects (on purpose) appears today as a rational approach for the design of active MOFs. Similarly to zeolite post-treatments, post-modifications of MOFs by linker or metal cation exchange appear to be methods of choice. Despite the mild acidity of defective MOFs, we can account for very active MOFs in a number of catalytic applications which show higher performances than zeolites or benchmark catalysts.

  7. Molluscicidal activity of various solvent extracts from Solanum nigrum var. villosum L. aerial parts against Galba truncatula

    PubMed Central

    Hammami, H.; Mezghani-Jarraya, R.; Damak, M.; Ayadi, A.


    Molluscicidal activity of Solanum nigrum var. villosum (morelle velue) extracts and their fractions were tested against the mollusca gastropoda Galba truncatula intermediate host of Fasciola hepatica. The results indicated that the hydro-methanol (MeOH-H2O) immature fruit extract possess the highest molluscicidal activity (LC50 = 3.96 mg/L) against Galba truncatula compared with other tested compounds. After acido-basic treatment, the methanolic extract fraction isolated from the immature fruits and the richest in alkaloids was the most toxic (LC50 = 1.65 mg/L). The fractions richest in saponosides obtained from the hydromethanolic and methanolic extracts of immature fruits showed interesting molluscicidal activities (LC50 = 6.15 mg/L and LC50 = 7.91 mg/L, respectively). The observed molluscicide activity could be attributed to the presence of alkaloids or saponosides. So, the immature fruits of Solanum nigrum var. villosum could be substrates of choice for molluscicide activity. In addition, total alkaloids and saponosides present in this plant deserve further investigations in order to identify the active principles and demonstrate their activities on mollusks in their natural habitat. According to the World Health Organization’s guidelines on screening for plant molluscicides, use of these fractions may add to the arsenal of methods to control snail transmitting fasciolosis in tropical and Third World countries where fasciolosis is a common disease. PMID:21395207

  8. Sorption of selenium anionic species on apatites and iron oxides from aqueous solutions.


    Duc, Myriam; Lefevre, Gregory; Fedoroff, Michel; Jeanjean, Janine; Rouchaud, J C; Monteil-Rivera, Fanny; Dumonceau, Jacques; Milonjic, Slobodan


    The sorption of selenite and selenate ions from aqueous solutions was investigated on hydroxyapatite, fluorapatite, goethite and hematite, in order to simulate the behavior of radioactive selenium in natural or artificial sorbing media. Correlation studies with acido-basic properties and solubility of the solids were also performed. The sorption is pH dependant, but these solids are very efficient for retaining selenite at pH values generally encountered in natural waters, with however higher K(d) values for oxides than apatites. Selenate ions are much less sorbed than selenite. Several methods such as electron microscopy and spectroscopic techniques were used to identify the sorption mechanisms. In the case of hydroxyapatite, sorption proceeds by substitution of phosphate groups in the lattice of the apatite crystal in the superficial layers of the solid. In the case of goethite and hematite, sorption can be interpreted and modeled by a surface complexation process, but there is a discrepancy between sorption site densities for selenite and for protons.

  9. Structures of nitrato-(2-hydroxybenzaldehydo) (2,2 Prime -bipyridyl)copper and nitrato-(2-hydroxy-5-nitrobenzaldehydo)(2,2 Prime -bipyridyl)copper

    SciTech Connect

    Chumakov, Yu. M.; Paladi, L. G.; Antosyak, B. Ya.; Simonov, Yu. A.; Tsapkov, V. I.; Bocelli, G.; Gulea, A. P.; Ginju, D.; Palomares-Sanchez, S. A.


    Nitrato-(2-hydroxy-5-nitrobenzaldehydo)(2,2 Prime -bipyridyl)copper (I) and nitrato-(2-hydroxybenzaldehydo)(2,2 Prime -bipyridyl)copper (II) were synthesized and characterized by X-ray diffraction. The coordination polyhedron of the central copper atom in complex I can be described as a distorted tetragonal pyramid whose base is formed by the phenol and carbonyl oxygen atoms of the monodeprotonated 2-hydroxy-5nitrobenzaldehyde molecule and the nitrogen atoms of the 2,2 Prime -bipyridyl ligand and whose apex is occupied by the oxygen atom of the nitrato group. In the crystal structure, complexes I are linked by the acido ligands and the NO{sub 2} groups of the aldehyde molecule into infinite chains. In complex II, the central copper atom is coordinated by 2-hydroxybenzaldehyde, 2,2 Prime -bipyridyl, and the nitrato group, resulting in the formation of centrosymmetric dimers. The coordination polyhedron of the central copper atom can be described as a bipyramid (4 + 1 + 1) with the same base as in complex I. The axial vertices of the bipyramid are occupied by the oxygen atom of the nitrato group and the bridging phenol oxygen atom of the adjacent complex related to the initial complex by a center of symmetry. In the crystal structure, complexes II are hydrogen bonded into infinite chains.

  10. A prototype of volume-controlled tidal liquid ventilator using independent piston pumps.


    Robert, Raymond; Micheau, Philippe; Cyr, Stéphane; Lesur, Olivier; Praud, Jean-Paul; Walti, Hervé


    Liquid ventilation using perfluorochemicals (PFC) offers clear theoretical advantages over gas ventilation, such as decreased lung damage, recruitment of collapsed lung regions, and lavage of inflammatory debris. We present a total liquid ventilator designed to ventilate patients with completely filled lungs with a tidal volume of PFC liquid. The two independent piston pumps are volume controlled and pressure limited. Measurable pumping errors are corrected by a programmed supervisor module, which modifies the inserted or withdrawn volume. Pump independence also allows easy functional residual capacity modifications during ventilation. The bubble gas exchanger is divided into two sections such that the PFC exiting the lungs is not in contact with the PFC entering the lungs. The heating system is incorporated into the metallic base of the gas exchanger, and a heat-sink-type condenser is placed on top of the exchanger to retrieve PFC vapors. The prototype was tested on 5 healthy term newborn lambs (<5 days old). The results demonstrate the efficiency and safety of the prototype in maintaining adequate gas exchange, normal acido-basis equilibrium, and cardiovascular stability during a short, 2-hour total liquid ventilator. Airway pressure, lung volume, and ventilation scheme were maintained in the targeted range.

  11. Self-powered biosensor for ascorbic acid with a Prussian blue electrochromic display.


    Zloczewska, Adrianna; Celebanska, Anna; Szot, Katarzyna; Tomaszewska, Dorota; Opallo, Marcin; Jönsson-Niedziolka, Martin


    We report on the development of a nanocarbon based anode for sensing of ascorbic acid (AA). The oxidation of AA on this anode occurs at a quite low overpotential which enables the anode to be connected to a biocathode to form an ascorbic acid/O2 biofuel cell that functions as a self-powered biosensor. In conjunction with a Prussian blue electrochromic display the anode can also work as a truly self-powered sensor. The oxidation of ascorbic acid at the anode leads to a reduction of the Prussian blue in the display. The reduced form of Prussian blue, called Prussian white, is transparent. The rate of change from blue to colourless is dependent on the concentration of ascorbic acid. The display can easily be regenerated by connecting it to the biocathode which returns the Prussian blue to its oxidized form. In this way we have created the first self-powered electrochromic sensor that gives quantitative information about the analyte concentration. This is demonstrated by measuring the concentration of ascorbic acid in orange juice. The reported quantitative read-out electrochromic display can serve as a template for the creation of cheap, miniturizable sensors for other relevant analytes.

  12. Inhibition of Neutral red photolysis with different antioxidants.


    Rimpapa, Zlatan; Sofić, Emin; Sapcanin, Aida; Toromanović, Jasmin; Tahirović, Ismet


    Neutral red is a dye the azine structure which has been used as an acido-base indicator and a dye in histochemistry. In 1960 Goldhaber introduced Neutral red into the medium of resorbing bone cultures to localize the osteoclast in the living cultures. Using time-lapse microcinematography in order to follow the osteoclasts, he reported excellent contrast could be obtained with Neutral red due to the avidity of osteoclasts for this dye. Unfortunately, however, the photodynamic effect resulting from subsequent exposure of these cultures to light precluded this approach, and again in 1963. it was observed that the death of the osteoclasts was probably due to a photodynamic effect related to the dye in the cell, the presence of oxygen and the frequent exposure of light by our time-lapse photography. VIS and UV irradiation induced photolysis of Neutral red, and from Neutral red cation produced with photons a Neutral red radical. This Neutral red radical can be inhibited with action of an antioxidant, such as melatonin, glutathione, ascorbic acid, E vitamin, etc. We developed an assay with Neutral red photolysis which utilizes a VIS and UV irradiation technique for quantification the inhibition of photolysis with action of an antioxidant. In this method Neutral red acts double, as a free radical generator and as a photosensitizer.

  13. Development of a screening method for the analysis of organic pollutants in water using dual stir bar sorptive extraction-thermal desorption-gas chromatography-mass spectrometry.


    Tölgyessy, Peter; Vrana, Branislav; Krascsenits, Zoltán


    The development of a method for screening of organic compounds with a wide range of physico-chemical properties in water, based on dual stir bar sorptive extraction coupled with thermal desorption and gas chromatography-mass spectrometry (dual SBSE-TD-GC-MS) is described. The investigated water sample is divided into two aliquots and extracted with stir bar sorptive extraction at two different conditions: using addition of methanol or sodium chloride, respectively. Following extraction, the two stir bars are inserted into the same glass thermal desorption liner and are simultaneously desorbed and analysed by GC-MS. The method optimisation was performed using 45 environmentally harmful substances with different volatilities (boiling point from 193 to 495°C), polarity (logK(ow) from 2.17 to 8.54) and acido-basic properties. The majority of model compounds was selected from the EU list of priority substances in the field of water policy and from the US EPA method 625, respectively. Optimisation was performed for extraction parameters (sample volume, extraction time, stirring rate, addition of modifiers) as well as for the thermal desorption conditions (desorption flow, desorption time, cryofocusing temperature). Performance characteristics (recovery, repeatability, carryover, linearity, limits of detection and quantification) were determined for the optimised method. An example of analysis of a contaminated groundwater sample is presented.

  14. Sulfoquinovose synthase – an important enzyme in the N-glycosylation pathway of Sulfolobus acidocaldarius

    PubMed Central

    Meyer, Benjamin H.; Zolghadr, Behnam; Peyfoon, Elham; Pabst, Martin; Panico, Maria; Morris, Howard R.; Haslam, Stuart M.; Messner, Paul; Schäffer, Christina; Dell, Anne; Albers, Sonja-Verena


    Summary Recently, the Surface (S)-layer glycoprotein of the thermoacidophilic crenarchaeote Sulfolobus acido-caldarius was found to be N-glycosylated with a heterogeneous family of glycans, with the largest having a composition Glc1Man2GlcNAc2 plus 6-sulfoquinovose. However, genetic analyses of genes involved in the N-glycosylation process in Crenarchaeota were missing so far. In this study we identify a gene cluster involved in the biosynthesis of sulfoquinovose and important for the assembly of the S-layer N-glycans. A successful markerless in-frame deletion of agl3 resulted in a decreased molecular mass of the S-layer glycoprotein SlaA and the flagellin FlaB, indicating a change in the N-glycan composition. Analyses with nanoLC ES-MS/MS confirmed the presence of only a reduced trisaccharide structure composed of Man1GlcNAc2, missing the sulfoquinovose, a mannose and glucose. Biochemical studies of the recombinant Agl3 confirmed the proposed function as a UDP-sulfoquinovose synthase. Furthermore, S. acidocaldarius cells lacking agl3 had a significantly lower growth rate at elevated salt concentrations compared with the background strain, underlining the importance of the N-glycosylation to maintain an intact and stable cell envelope, to enable the survival of S. acidocaldarius in its extreme environment. PMID:22059775

  15. [Phenotypic variations in Aicardi-Goutieres syndrome caused by RNASEH2B gene mutations: report of two new cases].


    Ortiz-Madinaveitia, Saturnino; Conejo-Moreno, David; López-Pisón, Javier; Peña-Segura, José Luis; Serrano-Madrid, M Luisa; Durán-Palacios, Ingrid C; Peláez-Cabo, Pilar


    Introduccion. El sindrome de Aicardi-Goutieres es un trastorno inmunitario raro debido a mutaciones en siete genes que codifican proteinas llamadas TREX1, el complejo ribonucleasa H2, SAMHD1, ADAR e IFIH1 (MAD5), las cuales estan implicadas en el metabolismo de los acidos nucleicos. A continuacion se presentan dos nuevos casos por mutacion en el gen RNASEH2B, uno de los cuales presenta una mutacion no descrita hasta la fecha. Casos clinicos. Caso 1: varon que consulto porque desde los 5 meses, coincidiendo con cuadros febriles de repeticion, presentaba perdida de los items madurativos adquiridos hasta la fecha. Caso 2: niño de 4 meses que desde los 2 meses mostraba gran irritabilidad con dificultades en la alimentacion, asociado a un grave retraso psicomotor. En ambos casos se constato un aumento de las pterinas en el liquido cefalorraquideo, principalmente de la neopterina, con calcificaciones en los ganglios basales. El diagnostico se confirmo mediante secuenciacion del gen RNASEH2B; el caso 2 presentaba una mutacion no descrita en la literatura medica. Conclusiones. Los casos corresponden a la descripcion clasica realizada por Aicardi-Goutieres. Debe tenerse en cuenta este sindrome ante un paciente con un cuadro de encefalopatia subaguda de comienzo en el primer año de vida, distonia/espasticidad en grado variable e importante afectacion/regresion del desarrollo psicomotor, especialmente si asocia aumento de las pterinas (neopterina) en el liquido cefalorraquideo y calcificaciones en los ganglios basales.

  16. Molluscicidal activity of various solvent extracts from Solanum nigrum var. villosum L. aerial parts against Galba truncatula.


    Hammami, H; Mezghani-Jarraya, R; Damak, M; Ayadi, A


    Molluscicidal activity of Solanum nigrum var. villosum (morelle velue) extracts and their fractions were tested against the mollusca gastropoda Galba truncatula intermediate host of Fasciola hepatica. The results indicated that the hydro-methanol (MeOH-H2O) immature fruit extract possess the highest molluscicidal activity (LC50 = 3.96 mg/L) against Galba truncatula compared with other tested compounds. After acido-basic treatment, the methanolic extract fraction isolated from the immature fruits and the richest in alkaloids was the most toxic (LC50 = 1.65 mg/L). The fractions richest in saponosides obtained from the hydromethanolic and methanolic extracts of immature fruits showed interesting molluscicidal activities (LC50 = 6.15 mg/L and LC50 = 7.91 mg/L, respectively). The observed molluscicide activity could be attributed to the presence of alkaloids or saponosides. So, the immature fruits of Solanum nigrum var. villosum could be substrates of choice for molluscicide activity. In addition, total alkaloids and saponosides present in this plant deserve further investigations in order to identify the active principles and demonstrate their activities on mollusks in their natural habitat. According to the World Health Organization's guidelines on screening for plant molluscicides, use of these fractions may add to the arsenal of methods to control snail transmitting fasciolosis in tropical and Third World countries where fasciolosis is a common disease.

  17. Molecular epidemiology of human cases of tuberculosis by Mycobacterium bovis in Mexico.


    Milián-Suazo, Feliciano; Pérez-Guerrero, Laura; Arriaga-Díaz, Camila; Escartín-Chávez, Minerva


    The purpose of this study was to evaluate the role of Mycobacterium bovis in human cases of tuberculosis (TB) in an endemic area of the disease in cattle. Sputum, urine and other tissue samples were obtained from: (1) TB-symptomatic patients, (2) dairy farm workers and (3) abattoir workers. Samples of macroscopic lesions suspicious of TB were also obtained from cattle at slaughter in the same geographic area. A total of 562 human samples were collected: 255 from symptomatic patients, 218 from farm workers and 93 from abattoir workers. Samples were analysed by the bacillus acido-alcohol resitant (BAAR) and polymerase chain reaction (PCR) tests and cultured in Stonebrink and Löwenstein-Jensen. Spoligotyping was performed in all isolates obtained by culture and the DNA obtained by PCR. From the total number of human cases, 34 (6%) showed M. bovis spoligotype; eight spoligotypes from cattle showed an identical pattern to three spoligotypes from humans; a different set of spoligotypes from cattle (n = 8) had only one spacer difference to a set of spoligotypes from humans (n = 2). These results provide further evidence that infected cattle represent a risk to public health and support previous reports about the role of M. bovis in Mexican patients. There is no doubt that genotyping M. bovis isolates collected from cattle may have a substantial impact on our understanding of the epidemiology of TB.

  18. The effect of pH on the synthesis of stable Cu2O/CuO nanoparticles by sol-gel method in a glycolic medium

    NASA Astrophysics Data System (ADS)

    Zayyoun, N.; Bahmad, L.; Laânab, L.; Jaber, B.


    In this work, we demonstrate that using a glycolic medium, both stable CuO and Cu2O nanoparticles can be elaborated from Cu colloidal particles by adjusting their chemical environment, in particular the acido-basicity of the solution. In this context, the effect of pH on the sol-gel synthesis of Cu2O/CuO NPs was investigated. XRD results confirmed the formation of pure Cu2O with a cubic structure at lower pH (pH ≤ 6), whereas the pure monoclinic CuO was formed at higher pH (pH ≥ 12). TEM image indicates that the as-formed CuO NPs in basic pH are spherical in shape and their average size is found to be in the range of 4.5 nm. However, the as-obtained Cu2O NPs in acid pH are cubical, with an average diameter of about 3 nm, and agglomerated into large spherical particles under the effect of ethylene glycol. Using the UV-Vis spectroscopy, the measured band gap energies of the prepared Cu2O and CuO NPs are 2.07 and 4.08 eV respectively. FTIR results confirm the purity of the synthesized CuO and Cu2O nanoparticles.

  19. [Benign myoclonic epilepsy in infancy: natural history and behavioral and cognitive outcome].


    Domínguez-Carral, Jana; García-Peñas, Juan José; Pérez-Jiménez, M Ángeles; Fournier-Del Castillo, M Concepción; Carreras-Sáez, Inmaculada; Jiménez-Echevarría, Saioa


    Introduccion. La epilepsia mioclonica benigna del lactante (EMBL) es un sindrome electroclinico de caracteristicas homogeneas y bien definidas, considerado clasicamente de buen pronostico. Sin embargo, en los ultimos años se han publicado estudios con resultados variables en cuanto a evolucion neuropsicologica. Objetivo. Analizar la evolucion natural y el pronostico neurocognitivo y conductual de los pacientes con EMBL. Pacientes y metodos. Estudio retrospectivo de 10 pacientes con EMBL, con un periodo de seguimiento de mas de cinco años, durante los cuales se realizo una evaluacion neurocognitiva y conductual. Resultados. En el 60% de los pacientes las crisis se controlaron con acido valproico en monoterapia, y el 80% no presento nuevas crisis durante su seguimiento. El cociente intelectual de la cohorte se situo entre 74 y 93; tres pacientes tuvieron un cociente intelectual en rango de inteligencia limite, y seis, en rango de inteligencia media-baja. Nueve pacientes cumplieron criterios de trastorno por deficit de atencion/hiperactividad y dos asociaban otro trastorno del aprendizaje, uno de ellos trastorno de aprendizaje no verbal, y el otro, trastorno especifico de la lectoescritura. Todos los pacientes presentaron datos de pobre coordinacion motriz y visuoespacial, y tres fueron diagnosticados de trastorno de conducta. Conclusiones. El termino 'benigno' en la EMBL debe utilizarse con precaucion en cuanto a su pronostico neurocognitivo y conductual. El inicio precoz y un peor control de las crisis podrian suponer factores de riesgo de evolucion neuropsicologica desfavorable.

  20. [The essence of essential tremor: neurochemical bases].


    Gironell, A; Marin-Lahoz, J


    Introduccion. El temblor esencial es el trastorno del movimiento mas frecuente en el adulto. Se ha considerado una enfermedad benigna, pero puede ocasionar una importante discapacidad fisica y psicosocial. El tratamiento farmacologico sigue siendo poco satisfactorio. Su etiologia, fisiopatologia y anatomia siguen sin conocerse del todo. Objetivo. El conocimiento de las bases neuroquimicas es fundamental para el desarrollo de terapias mas eficaces. Se revisan los conocimientos actuales en este campo a fin de incentivar nuevas investigaciones e ideas que permitan mejorar la comprension de la enfermedad y que fomenten el desarrollo de nuevas terapias farmacologicas. Desarrollo. Se revisan los trabajos realizados hasta la fecha en humanos y en modelos animales de neurotransmisores (acido gamma-aminobutirico, glutamato, noradrenalina, serotonina, adenosina), proteinas y otros fenomenos neuroquimicos, como los canales de calcio de tipo T en el temblor esencial. Conclusiones. Se han descrito cuatro disfunciones neuroquimicas que acontecerian basicamente en el cerebelo y el nucleo olivar inferior: alteracion del sistema gabergico, aumento del rebote postinhibitorio mediante corrientes de calcio de tipo T, disminucion de los mecanismos de inhibicion neuronal y aumento de la actividad de los neurotransmisores excitatorios. Estas disfunciones neuroquimicas comportarian un aumento de la actividad de las neuronas profundas cerebelosas con actividad oscilatoria, que se trasladaria al nucleo del talamo y a la corteza motora, y comportarian la aparicion del temblor. Son necesarios nuevos estudios para poder confirmar estas hipotesis y seguir avanzando para conseguir tratamientos farmacologicos mas eficaces para los pacientes con temblor esencial.

  1. Assessment of carbonic anhydrase IX expression and extracellular pH in B-cell lymphoma cell line models

    PubMed Central

    Chen, Liu Qi; Howison, Christine M.; Spier, Catherine; Stopeck, Alison T.; Malm, Scott W.; Pagel, Mark D.; Baker, Amanda F.


    The expression of carbonic anhydrase (CA IX) and it’s relation to acidosis in lymphomas has not been widely studied. We investigated the protein expression of CA IX in a human B-cell lymphoma tissue microarray, and in Raji, Ramos, and Granta 519 lymphoma cell lines and tumor models, while also investigating the relation with hypoxia. An imaging method, acidoCEST MRI, was used to estimate lymphoma xenograft extracellular pH (pHe). Our results showed that clinical lymphoma tissues and cell line models in vitro and in vivo had moderate CA IX expression. Although in vitro studies showed that CA IX expression was induced by hypoxia, in vivo studies did not show this correlation. Untreated lymphoma xenograft tumor pHe had acidic fractions, and an Acidity Score was qualitatively correlated with CA IX expression. Therefore, CA IX is expressed in B-cell lymphomas and is qualitatively correlated with extracellular acidosis in xenograft tumor models. PMID:25130478

  2. Tuberculose pulmonaire à Brazzaville en hospitalisation pneumologique: impact du diagnostic tardif à l’infection au VIH sur les anomalies radiographiques

    PubMed Central

    Bemba, Esthel Lee Presley; Bopaka, Régis Gothard; Moyikoua, Régis; Ossibi-Ibara, Rolland; Ebenga-Somboko, Norela Bibiane; Toungou, Syn Nerval; Matondot, Paunel God’hervé; Ossale-Abacka, Boris Kevin; Okemba-Okombi, Franck Hardain; Mboussa, Joseph


    L’objectif de notre étude était de décrire les différents aspects radiographiques de la tuberculose pulmonaire selon le degré de l’immunodépression chez les patients VIH. Nous rapportons une étude rétrospective de 80 patients VIH positif non traités présentant une tuberculose pulmonaire, hospitalisés dans le service de Pneumo-phtisiologie de Brazzaville de Janvier 2013 à Janvier 2014. Notre échantillon était composé de 44 femmes (55%) et 36 hommes (45%) soit un sex ratio de 0,81. La moyenne d’âge était de 37,5±9,17ans, la moyenne du Taux de CD4 était de 153,13±86,6cell/mm3. La microscopie des expectorations à la recherche des bacilles acido-alcoolo-résistants était positive dans 75% des cas chez les patients ayant un taux de lymphocytes T CD4>200cell/ mm3. Les adénopathies médiastinales, les atteintes moyennes, inferieures du champ pulmonaire et la miliaire étaient plus fréquentes chez les patients ayant un taux de lymphocytes T CD4< 200cell/ mm3. L’immunodépression sévère est significativement associée à la présentation radiographique atypique de la tuberculose. PMID:27800112

  3. Cardiovascular risk factors in children and adolescents with anxiety disorders and their association with disease severity.


    Cheuiche Pires, Gabriela; Camboim Rockett, Fernanda; Abrahão Salum Júnior, Giovanni; Gus Manfro, Gisele; Bosa, Vera Lúcia


    Introducción: Evidencias sugieren que la ansiedad es una prediciente independiente de los eventos cardiovasculares adversos. Entretanto, pocos estudios evaluaron la presencia de factores de riesgo (FR) para estas enfermedades en ninos y adolescentes. Objetivos: Identificar la prevalencia de FR cardiovasculares en ninos y adolescentes diagnosticados con disturbio de ansiedad y su asociacion con la gravedad de la enfermedad. Metodología: Estudio transversal que avaluo FR nutricional, antropometricos, % de gordura corporal (CG), presion arterial (PA), nivel de actividad fisica y escalas de sintomas y gravedad de la ansiedad. Resultados: 65 ninos y adolescentes (8.6 } 1.7 anos) fueron incluidos en el estudio. Cuanto a los FR, el consumo excesivo de acidos grasos saturados (52.3%), indice de masa corporal alto (50.8%), PA alterada (50.8%) y la falta de ejercicio fisico (50.0%) fueron los mas prevalecientes. Hubo asociacion significativa entre la mayor gravedad del disturbio y el acumulo de ≥ 6 FR (p=0,026), exceso de gordura abdominal medida por la circunferencia de cintura (p=0.019) y por el indice de conicidad (p=0.053) y exceso en el % GC (p=0.044). Conclusión: Los resultados encontrados indican que hay una alta prevalencia de FR cardiovascular en la amuestra estudiada y los pacientes mas graves presentaron mayor riesgo. La caracterizacion del perfil de riesgo en las poblaciones con predisposicion a las enfermedades cardiovasculares es crucial para la elaboracion de estrategias de intervencion que oportunicen la reduccion en la prevalencia de estas enfermedades.

  4. Niche specialization of terrestrial archaeal ammonia oxidizers.


    Gubry-Rangin, Cécile; Hai, Brigitte; Quince, Christopher; Engel, Marion; Thomson, Bruce C; James, Phillip; Schloter, Michael; Griffiths, Robert I; Prosser, James I; Nicol, Graeme W


    Soil pH is a major determinant of microbial ecosystem processes and potentially a major driver of evolution, adaptation, and diversity of ammonia oxidizers, which control soil nitrification. Archaea are major components of soil microbial communities and contribute significantly to ammonia oxidation in some soils. To determine whether pH drives evolutionary adaptation and community structure of soil archaeal ammonia oxidizers, sequences of amoA, a key functional gene of ammonia oxidation, were examined in soils at global, regional, and local scales. Globally distributed database sequences clustered into 18 well-supported phylogenetic lineages that dominated specific soil pH ranges classified as acidic (pH <5), acido-neutral (5 ≤ pH <7), or alkalinophilic (pH ≥ 7). To determine whether patterns were reproduced at regional and local scales, amoA gene fragments were amplified from DNA extracted from 47 soils in the United Kingdom (pH 3.5-8.7), including a pH-gradient formed by seven soils at a single site (pH 4.5-7.5). High-throughput sequencing and analysis of amoA gene fragments identified an additional, previously undiscovered phylogenetic lineage and revealed similar pH-associated distribution patterns at global, regional, and local scales, which were most evident for the five most abundant clusters. Archaeal amoA abundance and diversity increased with soil pH, which was the only physicochemical characteristic measured that significantly influenced community structure. These results suggest evolution based on specific adaptations to soil pH and niche specialization, resulting in a global distribution of archaeal lineages that have important consequences for soil ecosystem function and nitrogen cycling.

  5. pH as a Driver for Ammonia-Oxidizing Archaea in Forest Soils.


    Stempfhuber, Barbara; Engel, Marion; Fischer, Doreen; Neskovic-Prit, Ganna; Wubet, Tesfaye; Schöning, Ingo; Gubry-Rangin, Cécile; Kublik, Susanne; Schloter-Hai, Brigitte; Rattei, Thomas; Welzl, Gerhard; Nicol, Graeme W; Schrumpf, Marion; Buscot, Francois; Prosser, James I; Schloter, Michael


    In this study, we investigated the impact of soil pH on the diversity and abundance of archaeal ammonia oxidizers in 27 different forest soils across Germany. DNA was extracted from topsoil samples, the amoA gene, encoding ammonia monooxygenase, was amplified; and the amplicons were sequenced using a 454-based pyrosequencing approach. As expected, the ratio of archaeal (AOA) to bacterial (AOB) ammonia oxidizers' amoA genes increased sharply with decreasing soil pH. The diversity of AOA differed significantly between sites with ultra-acidic soil pH (<3.5) and sites with higher pH values. The major OTUs from soil samples with low pH could be detected at each site with a soil pH <3.5 but not at sites with pH >4.5, regardless of geographic position and vegetation. These OTUs could be related to the Nitrosotalea group 1.1 and the Nitrososphaera subcluster 7.2, respectively, and showed significant similarities to OTUs described from other acidic environments. Conversely, none of the major OTUs typical of sites with a soil pH >4.6 could be found in the ultra- and extreme acidic soils. Based on a comparison with the amoA gene sequence data from a previous study performed on agricultural soils, we could clearly show that the development of AOA communities in soils with ultra-acidic pH (<3.5) is mainly triggered by soil pH and is not influenced significantly by the type of land use, the soil type, or the geographic position of the site, which was observed for sites with acido-neutral soil pH.

  6. [Learning disorders in neurofibromatosis type 1].


    Garcia-Penas, J J


    Introduccion. Los deficits neurocognitivos y las dificultades de aprendizaje representan las complicaciones neurologicas mas frecuentes de la neurofibromatosis tipo 1 (NF1) en la edad pediatrica y son responsables de una importante morbilidad evolutiva. Los niños con NF1 muestran alteraciones en atencion, percepcion visual, lenguaje, funciones ejecutivas, logros academicos y conducta. Los estudios en modelos animales sugieren que las alteraciones de aprendizaje en la NF1 se relacionan con una potenciacion de la actividad Ras que conduce a un incremento de la inhibicion mediada por el acido gamma-aminobutirico (GABA) y a una disminucion de la potenciacion sinaptica a largo plazo. Objetivo. Describir la frecuencia, gravedad, tipologia y evolucion natural de los deficits neurocognitivos especificos de la NF1. Desarrollo. Los trastornos neurocognitivos y conductuales afectan al 50-80% de los niños con NF1. Se pueden definir tres subtipos de perfiles cognitivos en la NF1, incluyendo trastorno de aprendizaje global, trastorno especifico de aprendizaje y trastorno por deficit de atencion/hiperactividad aislado. Los deficits cognitivos mas frecuentes se relacionan con la alteracion visuoespacial, aunque tambien son importantes las alteraciones de la memoria de trabajo y de la funcion ejecutiva asociadas con la disfuncion de la corteza prefrontal. Conclusiones. Existe una gran frecuencia global de problemas cognitivos en la NF1, lo cual implica que la disfuncion neurocognitiva sea la mayor complicacion medica que afecta la calidad de vida de estos pacientes. El diagnostico y el tratamiento precoces de los trastornos de aprendizaje en estos niños son basicos para conseguir un mejor desempeño academico.

  7. [Long-term effect of policosanol on the functional recovery of non-cardioembolic ischemic stroke patients: a one year study].


    Sanchez, J; Illnait, J; Mas, R; Mendoza, S; Fernandez, L; Mesa, M; Vega, H; Fernandez, J; Reyes, P; Ruiz, D


    Introduccion. El ictus es una causa principal de mortalidad y discapacidad. El policosanol ha sido eficaz en modelos de isquemia cerebral. Este estudio investiga si el tratamiento a largo plazo con policosanol, añadido a la terapia con acido acetilsalicilico (AAS), dentro de los 30 dias posteriores a un ictus, es mejor que el placebo + AAS en la recuperacion de los pacientes. Pacientes y metodos. Estudio aleatorizado, doble ciego, controlado con placebo. Se incluyeron 80 pacientes (edad media: 69 años) que sufrieron un ictus en los 30 dias previos y con una puntuacion de 2-4 en la escala de Rankin modificada (mRS). Se distribuyeron aleatoriamente en dos grupos y recibieron policosanol + AAS o placebo + AAS durante 12 meses. Resultados. El tratamiento con policosanol + AAS disminuyo significativamente la puntuacion en la mRS desde el primer control intermedio (1,5 meses). El efecto del tratamiento incluso mejoro con la terapia a largo plazo. El numero de pacientes que alcanzaron valores de mRS menores o iguales a 1 fue superior en el grupo de policosanol + AAS (87,5%) que en el de placebo + AAS (0%). El tratamiento con policosanol + AAS aumento significativamente el indice de Barthel, disminuyo el colesterol LDL y aumento el colesterol HDL frente a placebo + AAS. Conclusiones. El tratamiento a largo plazo (12 meses) con policosanol + AAS fue mas efectivo que el tratamiento con placebo + AAS en la recuperacion funcional de los pacientes despues de sufrir un ictus isquemico no cardioembolico de moderada gravedad.

  8. [Electrical status epilepticus during sleep: a retrospective multi-centre study of 29 cases].


    Lorenzo-Ruiz, María; Miguel-Martin, Beatriz; García-Pérez, Asunción; Martínez-Granero, Miguel A; Aguilera-Albesa, Sergio; Yoldi-Petri, M Eugenia; Sánchez-Ruiz de Gordoa, Javier; Castro-De Castro, Pedro; Sánchez-Carpintero, Rocío


    Introduccion. El estado epileptico electrico durante el sueño (ESES) es un sindrome epileptico caracterizado por la presencia de descargas epilepticas tipo punta-onda lenta de manera muy persistente durante el sueño no REM. En la actualidad, el manejo de esta patologia es heterogeneo y no hay estudios controlados con los tratamientos utilizados, ni se ha comprobado si estos mejoran la evolucion cognitiva de los pacientes. Pacientes y metodos. Se revisan los pacientes diagnosticados de ESES durante 15 años en cuatro centros hospitalarios, se recoge la presentacion clinica, el manejo terapeutico y la evolucion clinica, y se compara con la bibliografia. Resultados. Se seleccionaron 29 pacientes con ESES, 20 de ellos idiopatico y 26 de ellos generalizado. Los farmacos con los que se consiguio mayor control de la actividad electrica fueron los corticoides/hormona adrenocorticotropa (ACTH), el clobazam y el levetiracetam. La mediana de duracion del ESES en los casos primarios fue de seis meses, y en los secundarios, el doble. El 45% de los pacientes mantuvo un cociente intelectual normal y un 40% presento en la evolucion discapacidad cognitiva de diferente grado. Conclusiones. El pronostico neuropsicologico evolutivo suele ser desfavorable y la evolucion cognitiva parece estar en relacion con la duracion del ESES y el area donde este concentrada la actividad epileptica, lo que sugiere que el mal pronostico, si se trata precozmente, se puede evitar. Los antiepilepticos mas frecuentemente utilizados son el acido valproico, la etosuximida y el levetiracetam, y en nuestra muestra tambien se utilizaron con frecuencia el clobazam y la lamotrigina. Los farmacos mas eficaces para el control del ESES fueron los corticoides/ACTH, el clobazam y el levetiracetam.

  9. Low temperature alkaline pH hydrolysis of oxygen-free Titan tholins

    NASA Astrophysics Data System (ADS)

    Brassé, C.; Buch, A.; Raulin, F.; Coll, P.; Poch, O.; Ramirez, S.


    Titan, the largest moon of Saturn, is known for its dense and nitrogen-rich atmosphere. The organic aerosols which are produced in Titan's atmosphere are objects of astrobiological interest. In this paper we focus on their potential chemical evolution when they reach the surface and interact with putative ammonia-water cryomagma[1]. In this context we have studied the evolution of alkaline pH hydrolysis of Titan tholins (produced by an experimental setup using a plasma DC discharge named PLASMA) at ambient and low temperature. However, we identified oxygenated molecules in non-hydrolyzed tholins meaning that oxygen gets in the PLASMA reactor during the tholins synthesis [2]. Following this preliminary study the synthesis protocol has been improved by isolating the whole device in a specially designed glove box which protect the PLASMA experiment from the laboratory atmosphere. After confirming the non-presence of oxygen in tholins produced with this new experimental setup, the study of oxygen-free tholins' evolution has been carried out. A recent study shows that the subsurface ocean may contain a lower fraction of ammonia (about 5wt% or less [3]), as previously described by other teams [2,4]. Thus new hydrolysis experiments will take this lower value into account. Additionally, a new report [5] provides upper and lower limits for the bulk content of Titan's interior for various gas species. It also shows that most of them are likely stored and dissolved in the subsurface water ocean. But considering the plausible acido-alkaline properties of the ammonia-water ocean, additional species could be dissolved in the ocean and present in the magma. They were also included in our hydrolysis experiments. Taking into account these new data, four different hydrolysis have been applied to oxygen-free tholins. For each type of hydrolysis, we also follow the influence of the hydrolysis temperature on the organic molecules production. The preliminary qualitative and quantitative

  10. [Control of epilepsy in adult patients with tuberous sclerosis].


    Gallardo-Tur, Alejandro; García-Martín, Guillermina; Chamorro-Muñoz, María Isabel; Romero-Godoy, Jorge; Romero-Acebal, Manuel


    Introduccion. La esclerosis tuberosa es una enfermedad genetica cuyas manifestaciones principales son la formacion de tumores neuroectodermicos, que asocia epilepsia secundaria muy frecuentemente. Objetivo. Describir el perfil epileptico, el control, la frecuencia de crisis y la efectividad del tratamiento en pacientes adultos con esclerosis tuberosa. Pacientes y metodos. Estudio descriptivo en el que se han incluido pacientes adultos (mayores de 14 anos) con diagnostico confirmado de esclerosis tuberosa. Se ha analizado la frecuencia y tipos de crisis. Se ha realizado un estudio y contabilizacion de los diferentes farmacos antiepilepticos en cada paciente, la frecuencia de uso de cada principio activo y un estudio comparativo entre control de crisis y tipo de terapia. Resultados. De 19 adultos estudiados, tuvieron crisis epilepticas 16 (84%). Presentaron control de crisis completo, crisis esporadicas y crisis frecuentes el 44%, 25% y 31%, respectivamente. Hubo frecuencia de crisis focales, generalizadas y ambas en el 38%, 6% y 25%, respectivamente. Estaban en tratamiento con farmacos antiepilepticos en monoterapia, biterapia y triterapia el 38%, 44% y 19%, respectivamente. El mas consumido globalmente fue el levetiracetam, seguido de la carbamacepina y el acido valproico. En monoterapia, el mas frecuente fue la carbamacepina, con mayor proporcion de control completo. Conclusiones. La epilepsia en la esclerosis tuberosa es relativamente benigna, y se consigue un aceptable control en la mayoria de casos con un numero de antiepilepticos acorde con lo aconsejado en las guias de tratamiento. Se observa estabilidad de lesiones, y no hay malignizacion en nuestra serie. El bajo numero de la muestra limita el estudio, pero se observan proporciones similares de efectividad del tratamiento respecto a otra serie publicada.

  11. [Folate and iron in fertile age women from a Venezuelan community affected by incidence of neural tube defects].


    Mariela, Montilva; Jham, Papale; Nieves, García-Casal María; Yelitza, Berné; Yudith, Ontiveros; Lourdes, Durán


    The objective of this transversal study was to determine folate and iron nutritional status of women in fertile age from Municipio Jiménez, Lara State, Venezuela. The sampling was probabilistic by conglomerates from the urban and rural areas, selecting 15 conglomerates from which women between 12 and 45 years (269), were studied. After signing informed consent, participating were interviewed for personal data, antecedents related to folate and iron, socioeconomic data (Graffar-Mendez Castellano method and unsatisfied basic needs). In blood sample was determined Hemoglobin, and Erythrocytic Folate (FE). Serum was obtained to determine Ferritin and Serum Folate (FS). 53.53% of the sample presented low FS levels, 10.78% were FS deficient. Severe FE deficiency was present in 80.7% of the cases, moderate deficiency affected 5.9%. For both tests, median was higher for women in treatment with Acido Fólico or pregnant (p = 0.000), median for FE was higher for adults (p = 0.001) and in non poor women (p = 0.011). There were no significant differences for coffee, alcohol, anticonceptive consumption, urban or rural resident or socioeconomic strata. The prevalence of anemia was 11.2% being significantly more frequent in adults than in adolescents (p = 0.029) and in urban women (p = 0.042). Low ferritin were found in 37.3% of the sample, the effect of different variables was not statistically significant. In conclusion, there is a high prevalence of iron and folate deficiencies in women of fertile age from Municipio Jiménez, which could constitute a conditioning factor for the appearance of neural tube defects.

  12. 13,16-Dimethyl Octacosanedioic Acid (iso-Diabolic Acid), a Common Membrane-Spanning Lipid of Acidobacteria Subdivisions 1 and 3 ▿ †

    PubMed Central

    Sinninghe Damsté, Jaap S.; Rijpstra, W. Irene C.; Hopmans, Ellen C.; Weijers, Johan W. H.; Foesel, Bärbel U.; Overmann, Jörg; Dedysh, Svetlana N.


    The distribution of membrane lipids of 17 different strains representing 13 species of subdivisions 1 and 3 of the phylum Acidobacteria, a highly diverse phylum of the Bacteria, were examined by hydrolysis and gas chromatography-mass spectrometry (MS) and by high-performance liquid chromatography-MS of intact polar lipids. Upon both acid and base hydrolyses of total cell material, the uncommon membrane-spanning lipid 13,16-dimethyl octacosanedioic acid (iso-diabolic acid) was released in substantial amounts (22 to 43% of the total fatty acids) from all of the acidobacteria studied. This lipid has previously been encountered only in thermophilic Thermoanaerobacter species but bears a structural resemblance to the alkyl chains of bacterial glycerol dialkyl glycerol tetraethers (GDGTs) that occur ubiquitously in peat and soil and are suspected to be produced by acidobacteria. As reported previously, most species also contained iso-C15 and C16:1ω7C as major fatty acids but the presence of iso-diabolic acid was unnoticed in previous studies, most probably because the complex lipid that contained this moiety was not extractable from the cells; it could only be released by hydrolysis. Direct analysis of intact polar lipids in the Bligh-Dyer extract of three acidobacterial strains, indeed, did not reveal any membrane-spanning lipids containing iso-diabolic acid. In 3 of the 17 strains, ether-bound iso-diabolic acid was detected after hydrolysis of the cells, including one branched GDGT containing iso-diabolic acid-derived alkyl chains. Since the GDGT distribution in soils is much more complex, branched GDGTs in soil likely also originate from other (acido)bacteria capable of biosynthesizing these components. PMID:21515715

  13. [Characteristics of patients with refractory epilepsy attended in a tertiary referral center in Costa Rica].


    Sanabria-Castro, A; Henriquez-Varela, F; Lara-Maier, S; Monge-Bonilla, C; Sittenfeld-Appel, M


    Introduccion. El 30% de los pacientes con epilepsia presenta convulsiones recurrentes, porcentaje que representa aproximadamente a 15 millones de personas en el mundo y constituye una poblacion escasamente descrita. Objetivo. Caracterizar sociodemografica y clinicamente la poblacion de pacientes diagnosticados con epilepsia refractaria en un hospital terciario de Costa Rica. Pacientes y metodos. Se analizan los registros medicos de los pacientes con epilepsia refractaria valorados en la unidad de epilepsia del Hospital San Juan de Dios de la Caja Costarricense del Seguro Social desde agosto de 2012 a octubre de 2014. Resultados. Se incluyen los expedientes clinicos de 91 pacientes. La edad media de inicio fue de 13,1 ± 11,1 años. Las crisis secundariamente generalizadas constituyen el tipo predominante (81,3%), la etiologia mas frecuente es la esclerosis mesial temporal (48,3%) y la mayoria de los pacientes presentaba examenes neurologicos normales y valoraciones neuro­psicologicas normales o bajas. Alrededor de la mitad (48,8%) de los pacientes habia sido medicada con un rango de 4-6 farmacos antiepilepticos, y los mas prescritos fueron lamotrigina, carbamacepina, acido valproico y fenitoina. Las principales recomendaciones en estos pacientes fueron: optimizacion de tratamiento, neurocirugia y reingreso. Se observan diferencias entre la edad de inicio y el sexo, la frecuencia de las crisis y el sexo, el tiempo de evolucion de la patologia y la cantidad de tratamientos fallidos, y el tiempo de evolucion de la enfermedad y la ocupacion. Conclusiones. Las caracteristicas sociodemograficas, el manejo de los pacientes, los farmacos antiepilepticos utilizados y las diferencias encontradas son similares a las descritas en otras latitudes.

  14. [Mango: agroindustrial aspects, nutritional/functional value and health effects].


    Wall-Medrano, Abraham; Olivas-Aguirre, Francisco J; Velderrain-Rodriguez, Gustavo R; González-Aguilar, A; de la Rosa, Laura A; López-Díaz, Jose A; Álvarez-Parrilla, Emilio


    Objetivo: Revisar y discutir la información más reciente sobre el valor agroindustrial, funcional y nutricional de uno de los frutos de mayor cultivo, exportación y consumo en México: el Mango. Métodos: Se realizó una búsqueda en diversas bases de datos (PubMed, Cochrane, ScienceDirect) y documentos de libre acceso (Google Scholar) sobre Mangifera indica L. Esta información fue posteriormente sub-clasificada en aspectos agroindustriales, nutricionales, funcionales y efectos a la salud. Resultados: Uno de cada veinte mangos consumidos mundialmente, es mexicano. “Ataulfo” es la variedad la de mayor importancia agronómica. El procesamiento mínimo de su pulpa (MP) genera residuos de cáscara (MC) y semilla con alto potencial nutracéutico. MP y MC son buenas fuentes de ascorbato, fructosa, fibra dietarias soluble (MP, almidones y ramnogalacturonanos) e insoluble (MC, ligninas y hemicelulosa) y lípidos funcionales (MP). MP y MC poseen un perfil de compuestos fenólicos (CF) monoméricos (MP) como el acido gálico y el protocatehuico y poliméricos (MC) como la -PGG asociados con efectos anti-obesigénicos, anti-inflamatorios, anti-cancerigenos y anti-diabeticos. Estos beneficios son dependientes de la bioaccesibilidad (liberación de su matriz alimentaria) y destino metabólico (biodisponibilidad) de estos CF. Discusión: El mango resulta una valiosa fuente de compuestos antioxidantes con comprobado beneficio a la salud. Sin embargo, factores como la variedad, temporalidad de cultivos, tratamientos pre y post-cosecha, extracción de bioactivos y algunas barreras fisiológicas pueden modificar su potencial nutracéutico.

  15. [Prevalence, type of epilepsy and use of antiepileptic drugs in primary care].


    Fernández-Suárez, Elena; Villa-Estébanez, Rubén; Garcia-Martinez, Alberto; Fidalgo-González, José A; Zanabili Al-Sibbai, Ahmad A; Salas-Puig, Javier


    Introduccion. La epilepsia es una enfermedad con gran repercusion social y economica. La prevalencia deberia ser usada como la base mas importante para planificar la prevencion secundaria y terciaria. Objetivos. Identificar los pacientes con diagnostico de epilepsia en un centro de atencion primaria y determinar la prevalencia, las caracteristicas demograficas, el tipo de sindrome epileptico y el uso de los farmacos antiepilepticos. Pacientes y metodos. Estudio descriptivo transversal retrospectivo. Incluyo 196 pacientes con diagnostico de epilepsia pertenecientes a un centro de salud y revision de la historia clinica hospitalaria, con el estudio de las variables sociodemograficas y clinicofarmacologicas. Resultados. Prevalencia de epilepsia: 8,4/1.000 habitantes. Edad media: 50,3 años. Sexo: 52,6%, hombres. Ambito: 79,6%, urbano. Antecedentes familiares de epilepsia: 14,8%. Tipo de epilepsia: focal sintomatica por ictus (14,3%), generalizada idiopatica (13,8%), focal criptogenica (8,7%), no clasificada (31,1%). Edad media al inicio de la crisis: 31,6 años. Comorbilidad neurologica o psiquiatrica: 62,8%. Ultima revision: el 18,9% sin tratamiento antiepileptico, el 56,6% en monoterapia y el 24,5% en politerapia. Libres de crisis: 76,5%. Farmacos mas prescritos: acido valproico, carbamacepina, fenitoina, lamotrigina y levetiracetam. Un 78,6% sin efectos secundarios. Fallecimiento: 4,1%. Conclusiones. La prevalencia de pacientes con epilepsia fue de 8,4/1.000 habitantes y predomina la focal sintomatica por ictus. Casi un tercio de los pacientes referia algun factor desencadenante de crisis, principalmente consumo de alcohol o fiebre. Predomina la monoterapia, los efectos secundarios son escasos y, en la ultima revision, la mayoria se hallaba libre de crisis.

  16. [The prevalence of obesity and metabolic syndrome in paediatric patients with epilepsy treated in monotherapy with valproic acid].


    Carmona-Vazquez, C R; Ruiz-Garcia, M; Pena-Landin, D M; Diaz-Garcia, L; Greenawalt, S R


    Introduccion. El acido valproico (VPA) es un antiepileptico util para controlar diferentes tipos de epilepsia. Tiene efectos colaterales y se asocia a incremento del peso corporal y a alteraciones metabolicas y endocrinas, entre ellas sindrome metabolico. Objetivo. Conocer la prevalencia de la obesidad y el sindrome metabolico en pacientes pediatricos con epilepsia tratados en monoterapia con VPA. Pacientes y metodos. Estudio transversal, observacional, analitico. Se estudiaron pacientes tratados con VPA entre 2010-2014, y se midio el indice de masa corporal (IMC), el perimetro abdominal, la presion arterial, la glucosa, los trigliceridos y las lipoproteinas de alta densidad (HDL), en busqueda de obesidad y sindrome metabolico. La obesidad se definio con un IMC mayor del percentil 95; el sindrome metabolico, con al menos tres de los siguientes criterios: perimetro abdominal mayor del percentil 90, presion arterial sistemica mayor del percentil 90, trigliceridos mayores de 110 mg/dL y HDL menor de 40 mg/dL. Resultados. Se estudiaron 47 pacientes con una edad media de 10,1 ± 4 años; el 51,06% eran varones. Ocho (17%) desarrollaron obesidad y, de ellos, dos (25%), sindrome metabolico. Tres pacientes desarrollaron sobrepeso (6%). Observamos diferencias estadisticamente significativas de media de edad comparados con los grupos de IMC, donde los pacientes obesos eran adolescentes (ANOVA; p = 0,0001), y aquellos que tomaban mas VPA al dia eran los obesos (ANOVA; p = 0,024). Conclusiones. Los pacientes tratados con VPA que se convierten en obesos pueden desarrollar sindrome metabolico. Requieren una monitorizacion cuidadosa y, ante la presencia de ganancia de peso, se debera valorar la retirada del farmaco.

  17. Methanotrophic activity and diversity of methanotrophs in volcanic geothermal soils at Pantelleria (Italy)

    NASA Astrophysics Data System (ADS)

    Gagliano, A. L.; D'Alessandro, W.; Tagliavia, M.; Parello, F.; Quatrini, P.


    Volcanic and geothermal systems emit endogenous gases by widespread degassing from soils, including CH4, a greenhouse gas twenty-five times as potent as CO2. Recently, it has been demonstrated that volcanic or geothermal soils are not only a source of methane, but are also sites of methanotrophic activity. Methanotrophs are able to consume 10-40 Tg of CH4 a-1 and to trap more than 50% of the methane degassing through the soils. We report on methane microbial oxidation in the geothermally most active site of Pantelleria (Italy), Favara Grande, whose total methane emission was previously estimated at about 2.5 Mg a-1 (t a-1). Laboratory incubation experiments with three top-soil samples from Favara Grande indicated methane consumption values of up to 59.2 nmol g-1 soil d.w. h-1. One of the three sites, FAV2, where the highest oxidation rate was detected, was further analysed on a vertical soil profile, the maximum methane consumption was measured in the top-soil layer, and values greater than 6.23 nmol g-1 h-1 were still detected up to a depth of 13 cm. The highest consumption rate was measured at 37 °C, but a still detectable consumption at 80 °C (> 1.25 nmol g-1 h-1) was recorded. The soil total DNA extracted from the three samples was probed by Polymerase Chain Reaction (PCR) using standard proteobacterial primers and newly designed verrucomicrobial primers, targeting the unique methane monooxygenase gene pmoA; the presence of methanotrophs was detected at sites FAV2 and FAV3, but not at FAV1, where harsher chemical-physical conditions and negligible methane oxidation were detected. The pmoA gene libraries from the most active site (FAV2) pointed to a high diversity of gammaproteobacterial methanotrophs, distantly related to Methylocaldum-Metylococcus genera, and the presence of the newly discovered acido-thermophilic Verrucomicrobia methanotrophs. Alphaproteobacteria of the genus Methylocystis were isolated from enrichment cultures under a methane

  18. Prise en charge diagnostique et thérapeutique de la tuberculose ganglionnaire en Tunisie

    PubMed Central

    Ben Brahim, Hajer; Kooli, Ikbel; Aouam, Abir; Toumi, Adnene; Loussaief, Chawki; Koubaa, Jamel; Chakroun, Mohamed


    La tuberculose ganglionnaire est la localisation extra-pulmonaire la plus fréquente de la tuberculose. Nous nous proposons dans ce travail d’étudier les modalités diagnostiques, thérapeutiques et évolutives de cette localisation. Il s'agit d'une étude rétrospective portant sur 100 cas de tuberculose ganglionnaire. L’âge moyen était de 35 ± 15 ans (15-85 ans). Aucun malade n’était VIH positif. L'aire cervicale était la plus touchée (93 cas). L'intradermo-réaction à la tuberculine était positive dans 76/91 cas (83,5%). L'examen bactériologique des prélèvements au niveau des ganglions atteints avait mis en évidence des bacilles acido-alcoolo-résistants à l'examen direct dans 2/31 cas (6,4%) et la culture avait isolé Mycobacteruim tuberculosis dans 1/31 cas (3,2%). La cytoponction ganglionnaire (FNAC) était évocatrice de tuberculose dans 35/42 cas (83,3%). La biopsie ganglionnaire était réalisée dans 69 cas et avait permis de retenir le diagnostic de tuberculose dans tous les cas. La FNAC, comparativement à la biopsie, avait permis de raccourcir significativement le délai de la prise en charge (15,1 vs 22,8 jours; p=0,001) et la durée d'hospitalisation (17,3 vs 24,6; p=0,004). La durée moyenne du traitement antituberculeux était de 9,8 ± 4,6 mois (7 à 44 mois). Le traitement chirurgical initial avait raccourci significativement la durée du traitement médical. Il n'avait pas d'impact sur le taux de guérison. Nous avons noté 10 cas de réponse paradoxale aux antituberculeux, quatre cas de résistance clinique et une rechute dans deux cas. La tuberculose ganglionnaire pose un problème diagnostique et thérapeutique. La microbiologie est d'un faible apport. La FNAC est un moyen diagnostique très utiles dans les pays endémiques et à faibles ressources. Un traitement médical seul permet d’éviter les inconvénients de la chirurgie. PMID:25829976

  19. Mucilaginibacter paludis gen. nov., sp. nov. and Mucilaginibacter gracilis sp. nov., pectin-, xylan- and laminarin-degrading members of the family Sphingobacteriaceae from acidic Sphagnum peat bog.


    Pankratov, Timofei A; Tindall, Brian J; Liesack, Werner; Dedysh, Svetlana N


    Two facultatively aerobic, heterotrophic bacteria capable of degrading pectin, xylan, laminarin and some other polysaccharides were obtained from the acidic Sphagnum peat bog Bakchar, in western Siberia, Russia, and were designated strains TPT18(T) and TPT56(T). Cells of these isolates are Gram-negative, non-motile, long rods that are covered by large capsules. On ageing, they transform into spherical L-forms. Strains TPT18(T) and TPT56(T) are acido- and psychrotolerant organisms capable of growth at pH 4.2-8.2 (with an optimum at pH 6.0-6.5) and at 2-33 degrees C (with an optimum at 20 degrees C). The major fatty acids are iso-C(15 : 0), anteiso-C(15 : 0), iso-C(17 : 0) 3-OH and summed feature 3 (iso-C(15 : 0) 2-OH and/or C(16 : 1)omega7c); the quinones are MK-7 and MK-6. Comparative 16S rRNA gene sequence analysis revealed that the novel strains share 97 % sequence similarity and belong to the family Sphingobacteriaceae; however, they are related only distantly to members of the genera Pedobacter (91.8-93.3 % similarity) and Sphingobacterium (89.6-91.2 % similarity). The DNA G+C content of strains TPT18(T) and TPT56(T) is 42.4 and 46.1 mol%, respectively. The low DNA-DNA hybridization value (42 %) and a number of phenotypic differences between strains TPT18(T) and TPT56(T) indicated that they represent two separate species. Since the two isolates are clearly distinct from all currently described members of the family Sphingobacteriaceae, we propose a novel genus, Mucilaginibacter gen. nov., containing two novel species, Mucilaginibacter gracilis sp. nov. and Mucilaginibacter paludis sp. nov. The type strains of Mucilaginibacter gracilis and Mucilaginibacter paludis are respectively TPT18(T) (=ATCC BAA-1391(T) =VKM B-2447(T)) and TPT56(T) (=ATCC BAA-1394(T) =VKM B-2446(T)).

  20. [Isolation and identification of Mycobacterium tuberculosis from the urine samples by conventional and molecular methods].


    Aslan, Gönül; Doruk, Erdal; Emekdaş, Gürol; Serin, M Sami; Direkel, Sahin; Bayram, Gül; Durmaz, Riza


    Genitourinary tuberculosis presents a challenge in diagnosis and treatment due to variations in clinical and radiological signs, insufficient patient history and difficulty in the isolation of the bacilli. The aim of this study was to isolate and identify Mycobacterium tuberculosis from the urine samples obtained from patients with suspected urinary tuberculosis admitted to our hospital by using Ehrlich-Ziehl-Neelsen (EZN), culture and polymerase chain reaction-restriction analysis (PCR-RFLP) methods. A total of 1004 urine samples collected from 437 patients who were admitted to our hospital between January 2004-July 2006, were inoculated on Löwenstein-Jensen (LJ) and/or BACTEC 12B (Becton Dickinson, USA) after decontamination and, direct preparations stained with EZN method were evaluated microscopically. M. tuberculosis complex (MTC) and mycobacteria other than tuberculosis (MOTT) were differentiated by nitro-alpha-acetylamino-beta-hydroxypropiophenone (NAP) test and the susceptibility testing for the MTC strains to primary antituberculosis drugs were performed by BACTEC 460 TB (Becton Dickinson, USA) system. PCR-RFLP method was performed for the identification of Mycobacterium spp. Twenty-two (5%) patients have yielded positive results by at least one of the conventional methods (EZN, LJ and/or BACTEC). Fifteen samples were positive for acido-resistant bacilli (ARB) by EZN method, and 17 samples were positive for mycobacterial growth in the cultures. Ten of 22 patients were found positive by both of the methods, while seven were culture positive but ARB negative and five were culture negative but ARB positive. These five patients received BCG treatment because of the presence of bladder tumor. Twelve (70.5%) of 17 strains isolated from culture were identified as MTC, while five (29.4%) were identified as M. fortuitum. Of 12 MTC isolates, eight (66.7%) were found susceptible to all of the antituberculosis agents, while one was found resistant to isoniazide (INH

  1. Rachianesthésie pour césarienne: facteurs de risque d'apparition de scores d'Apgar inférieur à 7 chez les nouveau-nés malgaches

    PubMed Central

    Rasolonjatovo, Tsiorintsoa Yvonne; Ravololonirina, Bako Minosoa Gilberthe; Randriamanantany, Zely Arivelo; Raveloson, Nasolotsiry Enintsoa


    Introduction La rachianesthésie est courante en obstétrique. L'hypotension artérielle maternelle apparaît dans 50-80%. Elle affecte l’équilibre acido-basique et l’état clinique du nouveau-né. Pour y remédier, l'usage de vasoconstricteurs est incontournable. L’éphédrine était de loin de premier choix en obstétrique. Dans les pays développés, elle est co-administrée avec la phényléphrine. A Madagascar, seule l’éphédrine reste disponible. Notre étude consiste à déterminer les facteurs de risque d'apparition du score d'Apgar inférieur à 7 chez les nouveau-nés. Méthodes Une étude rétrospective transversale, analytique, était effectuée à la Maternité de Befelatanana, Antananarivo Madagascar (Décembre 2010-Décembre 2011). Nous avons inclus 344 césariennes opérées sous rachianesthésie. Le critère principal de jugement était l'observation de score d'Apgar inférieur ou égal à 7 à la première minute. Les données étaient analysées sur logiciel Epi Info version 6.04 (IC à 95%, p bilatéral < 0.05). Résultats Le score d'Apgar était inférieur ou égal à 7 dans 42%. Les facteurs de risque retrouvés étaient la césarienne en urgence, la dose d’éphédrine dépassant 30mg ainsi que la baisse de la pression artérielle diastolique supérieure à 10% par rapport à sa valeur initiale (p respectif <<0.05). Conclusion La précarité de l’état clinique des nouveau-nés à la naissance est multifactorielle. La baisse de la pression artérielle diastolique associée à une dose élevée d’éphédrine est néfaste. De plus, l'augmentation de la catécholaminémie maternelle puis fœtale l'aggrave. PMID:25821536

  2. Methanotrophic activity and bacterial diversity in volcanic-geothermal soils at Pantelleria island (Italy)

    NASA Astrophysics Data System (ADS)

    Gagliano, A. L.; D'Alessandro, W.; Tagliavia, M.; Parello, F.; Quatrini, P.


    Volcanic and geothermal systems emit endogenous gases by widespread degassing from soils, including CH4, a greenhouse gas twenty-five times as potent as CO2. Recently, it has been demonstrated that volcanic/geothermal soils are source of methane, but also sites of methanotrophic activity. Methanotrophs are able to consume 10-40 Tg of CH4 a-1 and to trap more than 50% of the methane degassing through the soils. We report on methane microbial oxidation in the geothermally most active site of Pantelleria island (Italy), Favara Grande, whose total methane emission was previously estimated in about 2.5 t a-1. Laboratory incubation experiments with three top-soil samples from Favara Grande indicated methane consumption values up to 950 ng g-1 dry soil h-1. One of the three sites, FAV2, where the highest oxidation rate was detected, was further analysed on a vertical soil profile and the maximum methane consumption was measured in the top-soil layer but values > 100 ng g-1 h-1 were maintained up to a depth of 15 cm. The highest consumption rate was measured at 37 °C, but a still recognizable consumption at 80 °C (> 20 ng g-1 h-1) was recorded. In order to estimate the bacterial diversity, total soil DNA was extracted from Favara Grande and analysed using a Temporal Temperature Gradient gel Electrophoresis (TTGE) analysis of the amplified bacterial 16S rRNA gene. The three soil samples were probed by PCR using standard proteobacterial primers and newly designed verrucomicrobial primers targeting the unique methane monooxygenase gene pmoA; the presence of methanotrophs was detected in sites FAV2 and FAV3, but not in FAV1, where harsher chemical-physical conditions and negligible methane oxidation were detected. The pmoA gene libraries from the most active site FAV2 pointed out a high diversity of gammaproteobacterial methanotrophs distantly related to Methylococcus/Methylothermus genera and the presence of the newly discovered acido-thermophilic methanotrophs

  3. Overloaded elution band profiles of ionizable compounds in reversed-phase liquid chromatography: Influence of the competition between the neutral and the ionic species

    SciTech Connect

    Gritti, Fabrice; Guiochon, Georges A


    The parameters that affect the shape of the band profiles of acido-basic compounds under moderately overloaded conditions (sample size less than 500 nmol for a conventional column) in RPLC are discussed. Only analytes that have a single pK{sub a} are considered. In the buffer mobile phase used for their elution, their dissociation may, under certain conditions, cause a significant pH perturbation during the passage of the band. Two consecutive injections (3.3 and 10 {micro}L) of each one of three sample solutions (0.5, 5, and 50 mM) of ten compounds were injected on five C{sub 18}-bonded packing materials, including the 5 {micro}m Xterra-C{sub 18} (121 {angstrom}), 5 {micro}m Gemini-C{sub 18} (110 {angstrom}), 5 {micro}m Luna-C{sub 18}(2) (93 {angstrom}), 3.5 {micro}m Extend-C{sub 18} (80 {angstrom}), and 2.7 {micro}m Halo-C{sub 18} (90 {angstrom}). The mobile phase was an aqueous solution of methanol buffered at a constant {sub W}{sup W}pH of 6, with a phosphate buffer. The total concentration of the phosphate groups was constant at 50 mM. The methanol concentration was adjusted to keep all the retention factors between 1 and 10. The compounds injected were phenol, caffeine, 3-phenyl 1-propanol, 2-phenyl butyric acid, amphetamine, aniline, benzylamine, p-toluidine, procainamidium chloride, and propranololium chloride. Depending on the relative values of the analyte pK{sub a} and the buffer solution pH, these analytes elute as the neutral, the cationic, or the anionic species. The influence of structural parameters such as the charge, the size, and the hydrophobicity of the analytes on the shape of its overloaded band profile is discussed. Simple but general rules predict these shapes. An original adsorption model is proposed that accounts for the unusual peak shapes observed when the analyte is partially dissociated in the buffer solution during its elution.

  4. Evaluation of the implementation of the Xpert® MTB/RIF assay in Fiji.


    Gounder, A; Gounder, S; Reid, S A


    Contexte : Tous les tests Xpert® MTB/RIF réalisés dans les trois centres de traitement anti-tuberculeux aux Fidji entre juin 2012 et février 2013.Objectifs : Déterminer 1) le nombre de tests Xpert réalisés dans chaque centre, 2) l'association entre la qualité des crachats et le résultat du test Xpert, 3) l'accord entre Xpert et la microscopie des crachats acido alcoolo résistant (AFB) et la culture, et 4) le taux d'erreurs.Schéma : Revue rétrosp ective de dossiers.Résultats : Un total de 415 tests Xpert a été réalisé pendant la période d'étude. Mycobacterium tuberculosis a été détecté dans 69 (16.6%) échantillons. Aucune résistance à la rifampicine n'a été décelée. M. tuberculosis a été identifié dans 60 (18,7%) échantillons de crachats de bonne qualité. Un total de 43 (10,4%) erreurs sont survenues pendant la période d'étude. M. tuberculosis a été identifié dans 10 (2,9%) spécimens à frottis négatif. Il y a eu une concordance substantielle et presque parfaite entre les résultats du Xpert et ceux de la microscopie AFB (κ = 0,793) et de la culture (κ = 0,818), respectivement.Conclusion : En dépit de la bonne corrélation entre Xpert et les deux autres tests mise en évidence dans l'étude, Xpert ne peut toujours pas remplacer les tests de diagnostic de routine utilisés en première intention aux Fidji, en raison de contraintes logistiques et de problèmes de pérennité. Il est nécessaire de réaliser une évaluation ultérieure de la performance de ce test sur une période plus longue afin de mesurer sa valeur diagnostique dans la détection de cas à frottis négatif, Xpert positif aux Fidji.

  5. The role of extremophile in the redox reaction of Fe and As relating with the formation of secondary phase mineral in extreme environment, Norris Geyser Basin, Yellowstone National Park, USA

    NASA Astrophysics Data System (ADS)

    Koo, T. H.; Kim, J. Y.; Park, K. R.; Jung, D. H.; Geesey, G. G.; Kim, J. W.


    Redox reaction associated with microbial elemental respiration is a ubiquitous process in sediments and suspended particles at various temperatures or pH/Eh conditions. Particularly, changes in elemental redox states (structural or dissolved elemental form) induced by microbial respiration result in the unexpected biogeochemical reactions in the light of biotic/abiotic mineralization. The objective of the present study is, therefore to investigate the secondary phase mineralization through a-/biogeochemical Fe and As redox cycling in the acido-hyperhtermal Norris Geyser Basin (NGB) in Yellowstone National Park, USA, typical of the extreme condition. X-ray diffraction, scanning electron microscope with energy dispersive x-ray spectroscopy, X-ray absorption near edge structure, inductively coupled plasma-atomic emission spectrometer and liquid chromatography with ICP-mass spectroscopy with filtrated supernatant were performed for the mineralogical and hydro-geochemical analysis. The clay slurry collected from the active hot-spring of the NGB area (pH=3.5 and Temperature=78 ℃) was incubated with ("enrichment") or without the growth medium ("natural"). The control was prepared in the same condition except adding the glutaraldehyde to eliminate the microbial activity. The secondary phase mineral formation of the oxidative phase of Fe and As, and K identified as 'Pharmacosiderite' only appeared in the enrichment set suggesting a role of extremophiles in the mineral formation. The considerable population of Fe-oxidizer (Metallosphera yellowstonensis MK-1) and As-oxidizer (Sulfurihydrogenibium sp.) was measured by phylogenetic analysis in the present study area. The inhibition of As-oxidation in the low pH conditions was reported in the previous study, however the As-redox reaction was observed and consequently, precipitated the Pharmacosiderite only in the enrichment set suggesting a biotic mineralization. The present study collectively suggests that the microbial

  6. Tuberculosis diagnostics in Fiji: how reliable is culture?


    Reddy, M; Gounder, S; Reid, S A


    Contexte : L'examen microscopique de crachats à la recherche de bacilles acido-alcoolo résistants (AFB) et la culture de Mycobacterium tuberculosis sont des examens de première intention dans le diagnostic de la tuberculose (TB). La contamination des cultures de TB réduit la fiabilité du diagnostic.Objectif: Examiner les facteurs associés à la contamination des cultures de TB aux Fidji et les performances relatives de la culture et de l'AFB.Méthodes : Tous les examens réalisés au Laboratoire de Référence des Mycobacterium de Daulakao aux Fidji de 2010 à 2012 ont été inclus. Les variables comprenaient les résultats de l'AFB et de la culture, l'âge et le type de spécimen, le centre d'examen ayant envoyé l'échantillon et l'âge du patient.Résultats: Des 5708 spécimens enregistrés, 70% comprenaient à la fois les résultats du frottis AFB et de la culture. Une contamination est survenue dans 421 spécimens et 2,7% d'entre eux étaient soit dégradés, soit sans résultats. L'accord entre les deux tests était modéré (κ = 0,577). La culture avait plus de chances d'être positive quand le score du frottis AFB était plus élevé. La contamination de la culture était associée à la distance par rapport au laboratoire de référence, à l'âge de l'échantillon et à des facteurs liés à l'opérateur.Conclusion : Une plus grande rapidité de transmission des échantillons de crachats depuis le centre d'examens anti-tuberculeux ou l'adjonction de conservateurs aux spécimens de crachats pourrait amener une diminution du taux de contamination des cultures. L'introduction de techniques de cultures liquides combinée à la culture sur milieu Ogawa augmentera la sensibilité du diagnostic de la TB aux Fidji.

  7. Arthrite à pneumocoque chez un adulte immunocompétent

    PubMed Central

    Chemsi, Hicham; Chadli, Maryama; Sekhsokh, Yassine


    Les infections à pneumocoques sont avant tout respiratoires, ORL et méningées. Les infections ostéoarticulaires à pneumocoque ont la particularité de survenir dans moins de 20% des cas chez l'adulte sain. Habituellement, un ou plusieurs facteurs favorisants sont retrouvés. Toutefois, nous rapportons lors de cette observation le cas d'une arthrite à Streptococcus pneumoniae chez un adulte immunocompétent sans facteurs prédisposant. Patient âgé de 66 ans, diabétique de type II, a été hospitalisé pour une décompensation acido-cétosique et une monoarthrite du genou droit. Ce patient était fébrile (39°C) et présentait un genou droit inflammatoire en flexion avec rougeur et chaleur locale et un choc rotulien. Une ponction articulaire avec d'autres examens ont été réalisés pour confirmation d'une arthrite septique à pneumocoque. Le résultat de la ponction articulaire réalisée a montré un liquide jaune citron trouble avec 480 000 leucocytes/mm3 à prédominance polynucléaires neutrophiles. L'examen direct a montré des coccis à Gram positif en diplocoque, la culture a permis d'isoler un Streptococcus pneumoniae sensible à la pénicilline G. L’évolution clinique et biologique de l'arthrite du genou était favorable. Un déficit immunitaire, un asplénisme anatomique ou fonctionnel peuvent être en cause. L'alcoolisme est un facteur favorisant mais le mécanisme n'est pas clairement élucidé. La présence de matériel prothétique, peut favoriser une localisation septique. Ces facteurs de risque doivent être systématiquement recherchés, notamment en cas d'infection grave ou récidivante, une antibioprophylaxie ou une vaccination pouvant être proposées chez les sujets à haut risque. PMID:26327976

  8. Zinc, cadmium, and copper mobility and accumulation in reeds (Phragmites australis) in urban sediments from two stormwater infiltration basins

    NASA Astrophysics Data System (ADS)

    Bedell, J.-P.; Saulais, S.; Delolme, C.


    Infiltration basins are stormwater management techniques that are widely used to reduce stormwater volume. The settling of stormwater particles leads to a contaminated sediment layer at the basin surface. Phragmites australis used in constructed wetlands are widely present in infiltration basins. Such plant can play a role on the fate of heavy metals either directly by their uptake or indirectly by modification of physico-chemical characteristics of the sediment. The aim of this study is to assess Zn, Cd and Cu potential mobility and their bioaccumulation by reeds during plant's growth in urban sediments offering two different geochemical contexts. Methodology is based on the monitoring (in june, august and december) of physico-chemical characteristics of sediment deposit in two basins. These basins, "Minerve" and "Grézieu", located on both sides of Lyon city are characteristic of two different geochemical context. "Minerve" is in the east and "Grézieu" in the west part. The geology of the eastern part of Lyon is characterized by carbonated fluvio-glacial deposits. In the western part, the subsoil is mainly composed of gneiss and granit. Moreover, 20 cm of gravel and a sand layer were initially added at the surface of the "Grézieu" basin. In "Minerve", a clay material was initially added and a filter trench was built along the basin to allow water infiltration. We characterized the sediment deposit by the identification of their geochemical characteristics (Zn, Cu, Cd, total content, pH, CEC, C/N, carbonates and major elements contents …). Then we studied the potential mobility of the three metals by single chemical extraction (CaCl2 for the exchangeable phase, acetate buffer for the acido-soluble phase and diethylenetriamine-pentaacetic acid (DTPA) for the fraction associated to the organic matter). The accumulation of Zn, Cd and Cu in aerial parts and roots of the reeds was also measured. The results show clearly that "Grézieu" sediment is more enriched in

  9. Effet de la substitution du cuivre par du lithium sur les proprietes de l'oxyde spinelle lithium(x)cuivre(y-x)cobalt(3-y)oxygen(4) etudie pour l'electrocatalyse de la reaction de degagement de l'oxygene en milieu alcalin

    NASA Astrophysics Data System (ADS)

    Fatih, Khalid

    L'electrolyse de l'eau demeure la seule technologie industrielle de generation de l'hydrogene et de l'oxygene tres purs sans rejet de CO2 dans l'atmosphere, ce qui le rend tres attrayant par rapport a la combustion de carburants fossiles qui provoque presentement de serieux problemes environnementaux. Dans le but d'ameliorer le rendement de ce procede, nous avons developpe de nouveaux materiaux d'anode peu couteux, a base de l'oxyde mixte CuyCo3-yO 4, qui possedent une cinetique rapide pour la reaction de degagement de l'oxygene (RDO). Cette reaction suscite un interet particulier en raison de la surtension d'activation relativement elevee a l'anode qui cause la principale perte de rendement du procede. Une etude systematique a ete effectuee sur la substitution du Cu par du Li (0 a 40%), afin d'elucider les proprietes electrocatalytiques des oxydes LixCuy-xCo3-yO4. Ces oxydes, prepares sous forme de poudres par decomposition thermique des nitrates precurseurs entre 300 et 500°C, ont montre (DRX et FTIR) une structure spinelle inverse non-stcechiometrique avec une diminution du volume de la maille cristalline. La surface specifique par BET est d'environ 6 m2 g-1. Le pcn, obtenu par titrage acido-basique, a indique une diminution de la force du lien M-OH avec le taux du Li dans l'oxyde. Les analyses par XPS, realisees sur des films d'oxyde prepares par nebulisation reactive sur un substrat lisse de nickel, revelent un enrichissement de la surface en Cu a partir de 30% Li, et la presence des cations de surface Co2+, Co3+, Cu +, Cu2+ et Cu3+. La concentration de ce dernier montre un maximum a 10 et 20% Li. Suite a la substitution du Cu par du Li, la compensation de la charge serait assuree principalement par la formation d'especes Cu3+ pour les oxydes contenant jusqu'a 20% Li, et par la formation d'especes Co3+ aux taux de substitution superieurs. Les micrographies MEB montrent une morphologie hemispherique des particules d'oxyde reparties uniformement sur le substrat

  10. Peak shapes of acids and bases under overloaded conditions in reversed-phase liquid chromatography, with weakly buffered mobile phases of various pH: A thermodynamic interpretation

    SciTech Connect

    Gritti, Fabrice; Guiochon, Georges A


    We measured overloaded band profiles for a series of nine compounds (phenol, caffeine, 3-phenyl 1-propanol, 2-phenylbutyric acid, amphetamine, aniline, benzylamine, p-toluidine, and procainamidium chloride) on columns packed with four different C{sub 18}-bonded packing materials: XTerra-C{sub 18}, Gemini-C{sub 18}, Luna-C{sub 18}(2), and Halo-C{sub 18}, using buffered methanol-water mobile phases. The {sub W}{sup S}pH of the mobile phase was increased from 2.6 to 11.3. The buffer concentration (either phosphate, acetate, or carbonate buffers) was set constant at values below the maximum concentration of the sample in the band. The influence of the surface chemistry of the packing material on the retention and the shape of the peaks was investigated. Adsorbents having a hybrid inorganic/organic structure tend to give peaks exhibiting moderate or little tailing. The retention and the shape of the band profiles can easily be interpreted at {sub W}{sup S}pHs that are well above or well below the {sub W}{sup S}pK{sub a} of the compound studied. In contrast, the peak shapes in the intermediary pH range (i.e., close to the compound {sub W}{sup S}pK{sub a}) have rarely been studied. These shapes reveal the complexity of the competitive adsorption behavior of couples of acido-basic conjugated compounds at {sub W}{sup S}pHs that are close to their {sub W}{sup S}pK{sub a}. They also reveal the role of the buffer capacity on the resulting peak shape. With increasing {sub W}{sup S}pH, the overloaded profiles are first langmuirian (isotherm type I) at low {sub W}{sup S}pHs, they become S-shaped (isotherm type II), then anti-langmuirian (isotherm type III), S-shaped again at intermediate {sub W}{sup S}pHs, and finally return to a langmuirian shape at high {sub W}{sup S}pHs. A new general adsorption isotherm model that takes into account the dissociation equilibrium of conjugated acidic and basic species in the bulk mobile phase accounts for these transient band shapes. An

  11. Facteurs de risque de mortalité par tuberculose pulmonaire

    PubMed Central

    Janah, Hicham; Souhi, Hicham; Kouismi, Hatim; Mark, Karima; Zahraoui, Rachida; Benamor, Jouda; Soualhi, Mona; Bourkadi, Jamal Eddine


    La tuberculose est une maladie infectieuse transmissible provoquée par myco-bacterium tuberculosis (bacille de Koch ou BK). Elle représente, selon les estimations del'Organisation Mondiale de la Santé (OMS), l'une des pathologies infectieuses causant le plus de décès au niveau mondial avec plus de 1 million de décès par an. Pour déterminer les facteurs de risque de mortalité au cours de la tuberculose pulmonaire à microscopie positive nous avons mené une étude rétrospective portant sur tous les cas de tuberculose pulmonaire à microscopie positive et qui étaient décédés au cours de leur hospitalisation. Cette étude a colligé 1803 cas de tuberculose sur une période de 2 ans et demi dont 46 sont décédés. La prévalence de décès est de 2,55%. La population se répartit en 32 hommes et 14 femmes. L’âge moyen était de 53ans ± 17 ans. Le tabagisme était retrouvé chez la moitié des cas. Une comorbidité était retrouvée dans 43%, avec 17% de diabète. Le délai de diagnostic avait une médiane de 60 jours avec percentile (30j; 105j). La symptomatologie clinique était dominée par la toux, la dyspnée et les expectorations soit respectivement: 97,8%, 69,6% et 67,4% des cas. Sur le plan radiologique les lésions étaient diffuses et bilatérales dans 76,1% des cas. Tous les patients étaient mis sous SRHZ. 11% avaient présenté une toxicité aux antibacillaires (de type hépatiques dans 3 cas et neurologiques dans 2 cas). Le délai médian de décès était de 8,5 jours (5j; 17j). Les causes de décès retrouvées étaient: Une hépatite fulminante (3 cas), une décompensation acido-cétosique (3 cas), un SDRA (2 cas), des hémoptysies foudroyantes (2 cas), et respectivement un cas secondaire à une décompensation de BPCO, une décompensation cardiaque, une hypoglycémie et un tableau d'anasarque. Cette étude suggère que le terrain, le retard diagnostique et les effets secondaires du traitement sont les principaux facteurs de risque de

  12. Effects of Long-Term Acid-Mine Drainage Contamination on Diversity and Activity of Sulfate-Reducing Bacteria in a Natural Salt Marsh.

    NASA Astrophysics Data System (ADS)

    Moreau, J. W.; Banfield, J. F.


    -grained black muds that are distinguishable from coarser pyrite cinders, and exhibit a noticeably strong sulfide odor. Aero- and halo-tolerant SRB were enriched from circumneutral pH cores, and we hypothesize that acido-tolerant SRB may also be present. Analysis of restriction fragment length polymorphism of whole community 16S rDNA extracted from each core shows an expected increase in diversity between acidic and circumneutal sediments, and clone libraries from both contaminated and uncontaminated marsh sediments are being compared to assess the impact of long-term contamination. References: Webb et al. 1998, J. Appl. Microbio., 84, 240-248; Moreau et al. 2003, Amer. Min., in review; URS Corp. 2001, Report 51.09967067.00.

  13. Assessment of a sequential extraction protocol by examining solution chemistry and mineralogical evolution

    NASA Astrophysics Data System (ADS)

    Maubec, Nicolas; Pauwels, Hélène; Noël, Hervé; Bourrat, Xavier


    of them are able to leach several solid phases. In this context, the aim of the present study is to investigate the effectiveness and the selectivity of different reagents for metal extraction from target geochemical fraction. It is based on solid analyses with the use of X-ray diffraction and a scanning electron microscopy (SEM) coupled to a microRaman spectrometer in conjunction with chemical analyses of extracting solutions at each step. This methodology provides the opportunity to assess more accurately the effect of each reagent. The study focuses on extraction of Cu and Zn from sediment samples collected at two sites from river banks and characterized by presence of Quartz, Feldspar K, Micas, Kaolinite but with differences regarding accessory phases (pyrite, organic matter, iron oxy- hydroxide, calcite). The interaction of the samples with eight different reagents was assessed and compared (Ca(NO3)2 and CaCl2 for the exchangeable fraction; buffered solutions of sodium acetate/acetic acid at pH = 5.5 and pH = 5 for the acido-soluble fraction; hydroxylamine hydrochloride and a solution of ammonium oxalate/oxalic acid for reducible fraction; hydrogen peroxide and sodium hypochlorite for the oxidizable fraction. In-depth characterization of solid residue at each step allowed proposing the best protocol for both metals. Anderson, P., Davidson, C. M., Duncan, A. L., Littlejohn, D., Ure, A. M., and Garden, L. M. (2000). Column leaching and sorption experiments to assess the mobility of potentially toxic elements in industrially contaminated land. Journal of Environmental Monitoring, 2. Arey, J. S., Seaman, J. C., and Bertsch, P. M. (1999). Immobilization of uranium in contaminated sediments by hydroxyapatite addition. Environmental Science & Technology, 33, 337-342. Brannon, J. M., and Patrick, W. H. (1987). Fixation, transformation, and mobilization of arsenic in sediments.Environmental Science & Technology, 21, 450-459. Cornu, S., and Clozel, B. (2000). Extractions

  14. The extreme environments and their microbes as models for extraterrestrial life

    NASA Astrophysics Data System (ADS)

    Seckbach, J.; Oren, A.; Chela-Flores, J.


    Life exists almost everywhere on Earth. Presence of liquid water is a prerequisite for life (Oren, 2008). Living organisms are not only found in `normal' habitats (from the anthropocentric view). Many types, especially of microorganisms, not only tolerate harsh environmental conditions, but even thive in them. Such organisms that resist very harsh physical and chemical conditions in their habitats are termed `extremophiles'. Some extremophilic microorganisms are able to overcome more than one type of extreme conditions in their environment. For example, some `polyextremophiles' grow under hundreds of atmospheres of hydrostatic pressure (barophiles) and at very low, or alternatively at very high temperatures. In many hot springs there are acido-thermophiles that tolerate elevated temperatures and very low pH levels (e.g. the Cyanidium caldarium group, see Seckbach 1994). Members of Cyanidium are able to thrive in pure CO2, a condition not tolerated by most algae (Seckbach et al., 1970). Some thermophilic Archaea grow at temperatures up to 1130C and possibly even higher. In the Arctic and Antarctic regions and in the permafrost region in Siberia there are cold-loving microorganisms (psychrophiles) which are able to grow at -200C. Many types of Bacteria and Archaea tolerate extreme dryness, and spores of Bacillus and relatives that have been encapsulated within salt crystals may have survived in a dormant state for thousands and even millions of years, and still can be revived today. Other extremophiles tolerate salt concentrations up to saturation. Halophilic microorganisms such as found in the Dead Sea or in the Great Salt Lake have developed different strategies to cope with the high osmotic pressure of their environment. Some (e.g. the unicellular green alga Dunaliella salina) balance the salts in their medium by accumulating organic compounds such as glycerol. Others (halophilic Archaea of the order Halobacteriales, as well as a few representatives of the