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Sample records for binuclear non-heme iron

  1. Peroxo-Type Intermediates in Class I Ribonucleotide Reductase and Related Binuclear Non-Heme Iron Enzymes

    DEFF Research Database (Denmark)

    Kepp, Kasper Planeta; Bell, Caleb B.; Clay, MIchael D.;

    2009-01-01

    We have performed a systematic study of chemically possible peroxo-type intermediates occurring in the non-heme di-iron enzyme class la ribonucleotide reductase, using spectroscopically calibrated computational chemistry. Density functional computations of equilibrium structures, Fe-O and O...... in carboxylate conformations occurring during the O-2 reaction of this class of non-heme iron enzymes. Our procedure identifies and characterizes various possible candidates for peroxo intermediates experimentally observed along the ribonucleotide reductase dioxygen activation reaction. The study explores how...... water or a proton can bind to the di-iron site of ribonucleotide reductase and facilitate changes that affect the electronic structure of the iron sites and activate the site for further reaction. Two potential reaction pathways are presented: one where water adds to Fe1 of the cis-mu-1,2 peroxo...

  2. Systematic Perturbations of Binuclear Non-heme Iron Sites: Structure and Dioxygen Reactivity of de Novo Due Ferri Proteins.

    Science.gov (United States)

    Snyder, Rae Ana; Betzu, Justine; Butch, Susan E; Reig, Amanda J; DeGrado, William F; Solomon, Edward I

    2015-08-04

    DFsc (single-chain due ferri) proteins allow for modeling binuclear non-heme iron enzymes with a similar fold. Three 4A → 4G variants of DFsc were studied to investigate the effects of (1) increasing the size of the substrate/solvent access channel (G4DFsc), (2) including an additional His residue in the first coordination sphere along with three additional helix-stabilizing mutations [3His-G4DFsc(Mut3)], and (3) the three helix-stabilizing mutations alone [G4DFsc(Mut3)] on the biferrous structures and their O2 reactivities. Near-infrared circular dichroism and magnetic circular dichroism (MCD) spectroscopy show that the 4A → 4G mutations increase coordination of the diiron site from 4-coordinate/5-coordinate to 5-coordinate/5-coordinate, likely reflecting increased solvent accessibility. While the three helix-stabilizing mutations [G4DFsc(Mut3)] do not affect the coordination number, addition of the third active site His residue [3His-G4DFsc(Mut3)] results in a 5-coordinate/6-coordinate site. Although all 4A→ 4G variants have significantly slower pseudo-first-order rates when reacting with excess O2 than DFsc (∼2 s(-1)), G4DFsc and 3His-G4DFsc(Mut3) have rates (∼0.02 and ∼0.04 s(-1)) faster than that of G4DFsc(Mut3) (∼0.002 s(-1)). These trends in the rate of O2 reactivity correlate with exchange coupling between the Fe(II) sites and suggest that the two-electron reduction of O2 occurs through end-on binding at one Fe(II) rather than through a peroxy-bridged intermediate. UV-vis absorption and MCD spectroscopies indicate that an Fe(III)Fe(III)-OH species first forms in all three variants but converts into an Fe(III)-μ-OH-Fe(III) species only in the 2-His forms, a process inhibited by the additional active site His ligand that coordinatively saturates one of the iron centers in 3His-G4DFsc(Mut3).

  3. EPR of Mononuclear Non-Heme Iron Proteins

    OpenAIRE

    Gaffney, Betty J.

    2009-01-01

    Flexible geometry of three- to six-protein side-chain ligands to non-heme iron in proteins is the basis for widely diverse reactivites ranging from iron transport to redox chemistry. The gap between fixed states determined by x-ray analysis can be filled by spectroscopic study of trapped intermediates. EPR is a versatile and relatively quick approach to defining intermediate states in terms of the geometry and electronic structures of iron. A number of examples in which the iron chemistry of ...

  4. Non-heme iron as ferrous sulfate does not interact with heme iron absorption in humans.

    Science.gov (United States)

    Gaitán, Diego; Olivares, Manuel; Lönnerdal, Bo; Brito, Alex; Pizarro, Fernando

    2012-12-01

    The absorption of heme iron has been described as distinctly different from that of non-heme iron. Moreover, whether heme and non-heme iron compete for absorption has not been well established. Our objective was to investigate the potential competition between heme and non-heme iron as ferrous sulfate for absorption, when both iron forms are ingested on an empty stomach. Twenty-six healthy nonpregnant women were selected to participate in two iron absorption studies using iron radioactive tracers. We obtained the dose-response curve for absorption of 0.5, 10, 20, and 50 mg heme iron doses, as concentrated red blood cells. Then, we evaluated the absorption of the same doses, but additionally we added non-heme iron, as ferrous sulfate, at constant heme/non-heme iron molar ratio (1:1). Finally, we compare the two curves by a two-way ANOVA. Iron sources were administered on an empty stomach. One factor analysis showed that heme iron absorption was diminished just by increasing total heme iron (P heme iron as ferrous sulfate did not have any effect on heme iron absorption (P = NS). We reported evidence that heme and non-heme iron as ferrous sulfate does not compete for absorption. The mechanism behind the absorption of these iron sources is not clear.

  5. Invited award contribution for ACS Award in Inorganic Chemistry. Geometric and electronic structure contributions to function in bioinorganic chemistry: active sites in non-heme iron enzymes.

    Science.gov (United States)

    Solomon, E I

    2001-07-16

    Spectroscopy has played a major role in the definition of structure/function correlations in bioinorganic chemistry. The importance of spectroscopy combined with electronic structure calculations is clearly demonstrated by the non-heme iron enzymes. Many members of this large class of enzymes activate dioxygen using a ferrous active site that has generally been difficult to study with most spectroscopic methods. A new spectroscopic methodology has been developed utilizing variable temperature, variable field magnetic circular dichroism, which enables one to obtain detailed insight into the geometric and electronic structure of the non-heme ferrous active site and probe its reaction mechanism on a molecular level. This spectroscopic methodology is presented and applied to a number of key mononuclear non-heme iron enzymes leading to a general mechanistic strategy for O2 activation. These studies are then extended to consider the new features present in the binuclear non-heme iron enzymes and applied to understand (1) the mechanism of the two electron/coupled proton transfer to dioxygen binding to a single iron center in hemerythrin and (2) structure/function correlations over the oxygen-activating enzymes stearoyl-ACP Delta9-desaturase, ribonucleotide reductase, and methane monooxygenase. Electronic structure/reactivity correlations for O2 activation by non-heme relative to heme iron enzymes will also be developed.

  6. 21 CFR 862.1410 - Iron (non-heme) test system.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Iron (non-heme) test system. 862.1410 Section 862.1410 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... with widespread deposit in the tissues of two iron-containing pigments, hemosiderin and hemofuscin,...

  7. X-ray absorption spectroscopic studies of mononuclear non-heme iron enzymes

    Energy Technology Data Exchange (ETDEWEB)

    Westre, Tami E. [Stanford Univ., CA (United States)

    1996-01-01

    Fe-K-edge X-ray absorption spectroscopy (XAS) has been used to investigate the electronic and geometric structure of the iron active site in non-heme iron enzymes. A new theoretical extended X-ray absorption fine structure (EXAFS) analysis approach, called GNXAS, has been tested on data for iron model complexes to evaluate the utility and reliability of this new technique, especially with respect to the effects of multiple-scattering. In addition, a detailed analysis of the 1s→3d pre-edge feature has been developed as a tool for investigating the oxidation state, spin state, and geometry of iron sites. Edge and EXAFS analyses have then been applied to the study of non-heme iron enzyme active sites.

  8. X-ray absorption spectroscopic studies of mononuclear non-heme iron enzymes

    Energy Technology Data Exchange (ETDEWEB)

    Westre, T.E.

    1996-01-01

    Fe-K-edge X-ray absorption spectroscopy (XAS) has been used to investigate the electronic and geometric structure of the iron active site in non-heme iron enzymes. A new theoretical extended X-ray absorption fine structure (EXAFS) analysis approach, called GNXAS, has been tested on data for iron model complexes to evaluate the utility and reliability of this new technique, especially with respect to the effects of multiple-scattering. In addition, a detailed analysis of the 1s{yields}3d pre-edge feature has been developed as a tool for investigating the oxidation state, spin state, and geometry of iron sites. Edge and EXAFS analyses have then been applied to the study of non-heme iron enzyme active sites.

  9. Sugars increase non-heme iron bioavailability in human epithelial intestinal and liver cells.

    Directory of Open Access Journals (Sweden)

    Tatiana Christides

    Full Text Available Previous studies have suggested that sugars enhance iron bioavailability, possibly through either chelation or altering the oxidation state of the metal, however, results have been inconclusive. Sugar intake in the last 20 years has increased dramatically, and iron status disorders are significant public health problems worldwide; therefore understanding the nutritional implications of iron-sugar interactions is particularly relevant. In this study we measured the effects of sugars on non-heme iron bioavailability in human intestinal Caco-2 cells and HepG2 hepatoma cells using ferritin formation as a surrogate marker for iron uptake. The effect of sugars on iron oxidation state was examined by measuring ferrous iron formation in different sugar-iron solutions with a ferrozine-based assay. Fructose significantly increased iron-induced ferritin formation in both Caco-2 and HepG2 cells. In addition, high-fructose corn syrup (HFCS-55 increased Caco-2 cell iron-induced ferritin; these effects were negated by the addition of either tannic acid or phytic acid. Fructose combined with FeCl3 increased ferrozine-chelatable ferrous iron levels by approximately 300%. In conclusion, fructose increases iron bioavailability in human intestinal Caco-2 and HepG2 cells. Given the large amount of simple and rapidly digestible sugars in the modern diet their effects on iron bioavailability may have important patho-physiological consequences. Further studies are warranted to characterize these interactions.

  10. Heme and non-heme iron transporters in non-polarized and polarized cells

    Directory of Open Access Journals (Sweden)

    Yasui Yumiko

    2010-06-01

    Full Text Available Abstract Background Heme and non-heme iron from diet, and recycled iron from hemoglobin are important products of the synthesis of iron-containing molecules. In excess, iron is potentially toxic because it can produce reactive oxygen species through the Fenton reaction. Humans can absorb, transport, store, and recycle iron without an excretory system to remove excess iron. Two candidate heme transporters and two iron transporters have been reported thus far. Heme incorporated into cells is degraded by heme oxygenases (HOs, and the iron product is reutilized by the body. To specify the processes of heme uptake and degradation, and the reutilization of iron, we determined the subcellular localizations of these transporters and HOs. Results In this study, we analyzed the subcellular localizations of 2 isoenzymes of HOs, 4 isoforms of divalent metal transporter 1 (DMT1, and 2 candidate heme transporters--heme carrier protein 1 (HCP1 and heme responsive gene-1 (HRG-1--in non-polarized and polarized cells. In non-polarized cells, HCP1, HRG-1, and DMT1A-I are located in the plasma membrane. In polarized cells, they show distinct localizations: HCP1 and DMT1A-I are located in the apical membrane, whereas HRG-1 is located in the basolateral membrane and lysosome. 16Leu at DMT1A-I N-terminal cytosolic domain was found to be crucial for plasma membrane localization. HOs are located in smooth endoplasmic reticulum and colocalize with NADPH-cytochrome P450 reductase. Conclusions HCP1 and DMT1A-I are localized to the apical membrane, and HRG-1 to the basolateral membrane and lysosome. These findings suggest that HCP1 and DMT1A-I have functions in the uptake of dietary heme and non-heme iron. HRG-1 can transport endocytosed heme from the lysosome into the cytosol. These localization studies support a model in which cytosolic heme can be degraded by HOs, and the resulting iron is exported into tissue fluids via the iron transporter ferroportin 1, which is

  11. Effects of illumination and packaging on non-heme iron and color attributes of sliced ham.

    Science.gov (United States)

    Li, H; Li, C B; Xu, X L; Zhou, G H

    2012-08-01

    This study was designed to investigate effects of illumination and packaging on color of cooked cured sliced ham during refrigeration, and the possibility of decomposition of nitrosylheme under light and oxygen exposure. Three illumination levels and three packaging films with different oxygen transmission rates (OTRs) were used in two separate experiments during 35 days storage, and pH value, a* value, nitrosylheme, residual nitrite and non-heme iron were evaluated. Packaging OTRs had significant effects (P0.05) nitrosylheme concentration during storage. For both groups, storage time had a significant effect (Pheme iron in the packaging group were observed. Therefore, illumination level and packaging OTR had limited effects on overall pigment stability, but more discoloration and loss of redness occurred on the surface of products.

  12. Structural and Functional Models of Non-Heme Iron Enzymes : A Study of the 2-His-1-Carboxylate Facial Triad Structural Motif

    NARCIS (Netherlands)

    Bruijnincx, P.C.A.

    2007-01-01

    The structural and functional modeling of a specific group of non-heme iron enzymes by the synthesis of small synthetic analogues is the topic of this thesis. The group of non-heme iron enzymes with the 2-His-1-carboxylate facial triad has recently been established as a common platform for the activ

  13. Acute Copper and Ascorbic Acid Supplementation Inhibits Non-heme Iron Absorption in Humans.

    Science.gov (United States)

    Olivares, Manuel; Figueroa, Constanza; Pizarro, Fernando

    2016-08-01

    The objective of the study is to determine the effect of copper (Cu) plus the reducing agent ascorbic acid (AA) on the absorption of non-heme iron (Fe). Experimental study with block design in which each subject was his own control. After signing an informed consent, 14 adult women using an effective method of contraception and negative pregnancy test received 0.5 mg Fe, as ferrous sulfate, alone or with Cu, as copper sulfate, plus ascorbic acid (AA/Cu 2/1 molar ratio) at 4/1; 6/1 and 8/1 Cu/Fe molar ratios as an aqueous solution on days 1, 2, 14, and 15 of the study. Fe absorption was assessed by erythrocyte incorporation of iron radioisotopes (55)Fe and (59)Fe. Geometric mean (range ± SD) absorption of Fe at 4/1 and 6/1 Cu/Fe molar ratios (and AA/Cu 2/1 molar ratio) and Fe alone was 57.4 % (35.7-92.1 %), 64.2 % (45.8-89.9 %), and 38.8 % (20.4-73.8 %), respectively (ANOVA for repeated measures p absorption; however, Fe absorption at Cu/Fe 8/1 molar ratio was 47.3 % (27.7-80.8) (p = NS compared with Fe alone). It was expected that Fe absorption would have been equal or greater than at 4/1 and 6/1 molar ratios. Copper in the presence of ascorbic acid inhibits non-heme Fe absorption at Cu/Fe 8/1 molar ratio.

  14. A functional mimic of natural peroxidases : synthesis and catalytic activity of a non-heme iron/peptide hydroperoxide complex

    NARCIS (Netherlands)

    Choma, Christin T.; Schudde, Ebe P.; Kellogg, Richard M.; Robillard, George T.; Feringa, Ben L.

    1998-01-01

    Site-selective attachment of unprotected peptides to a non-heme iron complex is achieved by displacing two halides on the catalyst by peptide caesium thiolates. This coupling approach should be compatible with any peptide sequence provided there is only a single reduced cysteine. The oxidation activ

  15. Crystal Structure of the Non-heme Iron Dixoygenase PtlH in Pentalenolactone Biosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    You,Z.; Omura, S.; Ikeda, H.; Cane, D.; Jogl, G.

    2007-01-01

    The non-heme iron dioxygenase PtlH from the soil organism Streptomyces avermitilis is a member of the iron(II)/{alpha}-ketoglutarate-dependent dioxygenase superfamily and catalyzes an essential reaction in the biosynthesis of the sesquiterpenoid antibiotic pentalenolactone. To investigate the structural basis for substrate recognition and catalysis, we have determined the x-ray crystal structure of PtlH in several complexes with the cofactors iron, a-ketoglutarate, and the non-reactive enantiomer of the substrate, ent-1-deoxypentalenic acid, in four different crystal forms to up to 1.31 Angstroms resolution. The overall structure of PtlH forms a double-stranded barrel helix fold, and the cofactor-binding site for iron and a-ketoglutarate is similar to other double-stranded barrel helix fold enzymes. Additional secondary structure elements that contribute to the substrate-binding site in PtlH are not conserved in other double-stranded barrel helix fold enzymes. Binding of the substrate enantiomer induces a reorganization of the monoclinic crystal lattice leading to a disorder-order transition of a C-terminal {alpha}-helix. The newly formed helix blocks the major access to the active site and effectively traps the bound substrate. Kinetic analysis of wild type and site-directed mutant proteins confirms a critical function of two arginine residues in substrate binding, while simulated docking of the enzymatic reaction product reveals the likely orientation of bound substrate.

  16. 4-Nitrocatechol as a colorimetric probe for non-heme iron dioxygenases.

    Science.gov (United States)

    Tyson, C A

    1975-03-10

    4-Nitrocatechol is examined as an active site probe for non-heme iron dioxygenases and found to be of value, particularly with those containing iron in the Fe(II) oxidation state. 4-Nitrocatechol is astrong competitive inhibitor of substrate oxygenation by protocatechuate 3,4-dioxygenase, forming a reversible complex with this enzyme, and by pyrocatechase. The number of binding sites per enzyme molecule titrated spectrophotometrically with 4-nitrocatechol agrees with results from previous studies with either the principal substrate or other analogues, as expected of an effective probe. Despite these facts and the observation that both enzymes cleave the same substrates at the same carbon-carbon bond, the optical and electron paramagnetic resonance (EPR) spectra of their 4-nitrocatechol complexes are remarkably different. The 4-nitocatechol-protocatechuate 3,4-dioxygenase optical spectra resemble that of the 4-nitrocatecholate ion shifted 20 to 30 nm to longer wavelength. Concomitant with this change the EPR signal centered at g equal 4.28 shows increased rhombicity (g values at 4.74, 4.28, and 3.74). In contrast, the spectrum of the 4-nitrocatechol-pyrocatechase complex has a maximum at the same wavelength as that of a 1:1 solution of free Fe(II) and 4-nitrocatechol in the absence of enzyme after titration of the catecholic protons with base and the g equal 4.28 EPR signal is not resolved at liquid N-2 temperature. These changes are interpreted as resulting in part from a pronounced change in the ligand fields about the irons at the active sites which in the case of protocatechuate 3,4-dioxygenase leads to enzyme inactivation. The results also are the first indication that substrate analogues change their ionization form upon complexation with Fe (III) dioxygenases. The interaction of the probe with metapyrocatechase, an Fe(III) containing dioxygenase, and with several additional oxygenases and hydroperoxidases is also briefly examined. The probe is not specific

  17. Enhancement of non-heme iron absorption by anchovy (Engraulis japonicus) muscle protein hydrolysate involves a nanoparticle-mediated mechanism.

    Science.gov (United States)

    Wu, Haohao; Zhu, Suqin; Zeng, Mingyong; Liu, Zunying; Dong, Shiyuan; Zhao, Yuanhui; Huang, Hai; Lo, Y Martin

    2014-08-27

    The mechanisms by which meat enhances human absorption of non-heme iron remain unknown. Recently, anchovy (Engraulis japonicus) muscle protein hydrolysate (AMPH) was found to mediate the formation of nanosized ferric hydrolysis products in vitro. The current paper evaluates the effects of AMPH on the bioavailability and the intestinal speciation of non-heme iron in rats, followed by an investigation of cellular uptake pathways of in vitro-formed AMPH-stabilized nanosized ferric hydrolysis products (ANPs) by polarized human intestinal epithelial (Caco-2) cells. The hemoglobin regeneration efficiencies in anemic rats followed the order ferric citrate (9.79 ± 2.02%) iron in the groups of FC+AMPH, FeSO4, and ANPs were significantly lower than the corresponding hemoglobin regeneration efficiencies (P iron in intestinal iron absorption from FC+AMPH, FeSO4, and ANPs. Calcein-fluorescence measurements of the labile iron pool of polarized Caco-2 cells revealed the involvement of both divalent transporter 1 and endocytosis in apical uptake of ANPs, with endocytosis dominating at acidic extracellular pH. Overall, AMPH enhancement of non-heme iron absorption involves a nanoparticle-mediated mechanism.

  18. Interaction between Non-Heme Iron of Lipoxygenases and Cumene Hydroperoxide: Basis for Enzyme Activation, Inactivation, and Inhibition

    Energy Technology Data Exchange (ETDEWEB)

    Vahedi-Faridi, Ardeshir; Brault, Pierre-Alexandre; Shah, Priya; Kim, Yong-Wah; Dunham, William R.; Funk, Jr., Max O. (Toledo)

    2010-11-16

    Lipoxygenase catalysis depends in a critical fashion on the redox properties of a unique mononuclear non-heme iron cofactor. The isolated enzyme contains predominantly, if not exclusively, iron(II), but the catalytically active form of the enzyme has iron(III). The activating oxidation of the iron takes place in a reaction with the hydroperoxide product of the catalyzed reaction. In a second peroxide-dependent process, lipoxygenases are also inactivated. To examine the redox activation/inactivation dichotomy in lipoxygenase chemistry, the interaction between lipoxygenase-1 (and -3) and cumene hydroperoxide was investigated. Cumene hydroperoxide was a reversible inhibitor of the reaction catalyzed by lipoxygenase-1 under standard assay conditions at high substrate concentrations. Reconciliation of the data with the currently held kinetic mechanism requires simultaneous binding of substrate and peroxide. The enzyme also was both oxidized and largely inactivated in a reaction with the peroxide in the absence of substrate. The consequences of this reaction for the enzyme included the hydroxylation at C{beta} of two amino acid side chains in the vicinity of the cofactor, Trp and Leu. The modifications were identified by mass spectrometry and X-ray crystallography. The peroxide-induced oxidation of iron was also accompanied by a subtle rearrangement in the coordination sphere of the non-heme iron atom. Since the enzyme retains catalytic activity, albeit diminished, after treatment with cumene hydroperoxide, the structure of the iron site may reflect the catalytically relevant form of the cofactor.

  19. Interaction between non-heme iron of lipoxygenases and cumene hydroperoxide: basis for enzyme activation, inactivation, and inhibition.

    Science.gov (United States)

    Vahedi-Faridi, Ardeshir; Brault, Pierre-Alexandre; Shah, Priya; Kim, Yong-Wah; Dunham, William R; Funk, Max O

    2004-02-25

    Lipoxygenase catalysis depends in a critical fashion on the redox properties of a unique mononuclear non-heme iron cofactor. The isolated enzyme contains predominantly, if not exclusively, iron(II), but the catalytically active form of the enzyme has iron(III). The activating oxidation of the iron takes place in a reaction with the hydroperoxide product of the catalyzed reaction. In a second peroxide-dependent process, lipoxygenases are also inactivated. To examine the redox activation/inactivation dichotomy in lipoxygenase chemistry, the interaction between lipoxygenase-1 (and -3) and cumene hydroperoxide was investigated. Cumene hydroperoxide was a reversible inhibitor of the reaction catalyzed by lipoxygenase-1 under standard assay conditions at high substrate concentrations. Reconciliation of the data with the currently held kinetic mechanism requires simultaneous binding of substrate and peroxide. The enzyme also was both oxidized and largely inactivated in a reaction with the peroxide in the absence of substrate. The consequences of this reaction for the enzyme included the hydroxylation at C beta of two amino acid side chains in the vicinity of the cofactor, Trp and Leu. The modifications were identified by mass spectrometry and X-ray crystallography. The peroxide-induced oxidation of iron was also accompanied by a subtle rearrangement in the coordination sphere of the non-heme iron atom. Since the enzyme retains catalytic activity, albeit diminished, after treatment with cumene hydroperoxide, the structure of the iron site may reflect the catalytically relevant form of the cofactor.

  20. Cafestol to Tricalysiolide B and Oxidized Analogues: Biosynthetic and Derivatization Studies Using Non-heme Iron Catalyst Fe(PDP).

    Science.gov (United States)

    Bigi, Marinus A; Liu, Peng; Zou, Lufeng; Houk, K N; White, M Christina

    2012-12-01

    The tricalysiolides are a recently isolated class of diterpene natural products featuring the carbon backbone of the well-known coffee extract, cafestol. Herein we validate the use of our non-heme iron complex, Fe(PDP), as an oxidative tailoring enzyme mimic to test the proposal that this class of natural products derives from cafestol via cytochrome P-450-mediated furan oxidation. Thereafter, as predicted by computational analysis, C-H oxidation derivatization studies provided a novel 2° alcohol product as a single diastereomer.

  1. Dioxygen activation by a non-heme iron(II) complex: formation of an iron(IV)-oxo complex via C-H activation by a putative iron(III)-superoxo species.

    Science.gov (United States)

    Lee, Yong-Min; Hong, Seungwoo; Morimoto, Yuma; Shin, Woonsup; Fukuzumi, Shunichi; Nam, Wonwoo

    2010-08-11

    Iron(III)-superoxo intermediates are believed to play key roles in oxygenation reactions by non-heme iron enzymes. We now report that a non-heme iron(II) complex activates O(2) and generates its corresponding iron(IV)-oxo complex in the presence of substrates with weak C-H bonds (e.g., olefins and alkylaromatic compounds). We propose that a putative iron(III)-superoxo intermediate initiates the O(2)-activation chemistry by abstracting a H atom from the substrate, with subsequent generation of a high-valent iron(IV)-oxo intermediate from the resulting iron(III)-hydroperoxo species.

  2. Mononuclear non-heme iron enzymes with the 2-His-1-carboxylate facial triad: recent developments in enzymology and modeling studies

    NARCIS (Netherlands)

    Bruijnincx, P.C.A.; van Koten, G.; Klein Gebbink, R.J.M.

    2008-01-01

    Iron-containing enzymes are one of Nature’s main means of effecting key biological transformations. The mononuclear non-heme iron oxygenases and oxidases have received the most attention recently, primarily because of the recent availability of crystal structures of many different enzymes and the st

  3. Inclusion of guava enhances non-heme iron bioavailability but not fractional zinc absorption from a rice-based meal in adolescents

    Science.gov (United States)

    Assessing the bioavailability of non-heme iron and zinc is essential for recommending diets that meet the increased growth-related demand for these nutrients. We studied the bioavailability of iron and zinc from a rice-based meal in 16 adolescent boys and girls, 13–15 y of age, from 2 government-run...

  4. X-ray absorption spectroscopy of soybean lipoxygenase-1 : Influence of lipid hydroperoxide activation and lyophilization on the structure of the non-heme iron active site

    NARCIS (Netherlands)

    Vliegenthart, J.F.G.; Heijdt, L.M. van der; Feiters, M.C.; Navaratnam, S.; Nolting, H.-F.; Hermes, C.; Veldink, G.A.

    1992-01-01

    X-ray absorption spectra at the Fe K-edge of the non-heme iron site in Fe(II) as well as Fe(III) soybean lipoxygenase-1, in frozen solution or lyophilized, are presented; the latter spectra were obtained by incubation of the Fe(II) enzyme with its product hydroperoxide. An edge shift of about 23 eV

  5. Geometric and electronic structure contributions to function in non-heme iron enzymes.

    Science.gov (United States)

    Solomon, Edward I; Light, Kenneth M; Liu, Lei V; Srnec, Martin; Wong, Shaun D

    2013-11-19

    Mononuclear non-heme Fe (NHFe) enzymes play key roles in DNA repair, the biosynthesis of antibiotics, the response to hypoxia, cancer therapy, and many other biological processes. These enzymes catalyze a diverse range of oxidation reactions, including hydroxylation, halogenation, ring closure, desaturation, and electrophilic aromatic substitution (EAS). Most of these enzymes use an Fe(II) site to activate dioxygen, but traditional spectroscopic methods have not allowed researchers to insightfully probe these ferrous active sites. We have developed a methodology that provides detailed geometric and electronic structure insights into these NHFe(II) active sites. Using these data, we have defined a general mechanistic strategy that many of these enzymes use: they control O2 activation (and limit autoxidation and self-hydroxylation) by allowing Fe(II) coordination unsaturation only in the presence of cosubstrates. Depending on the type of enzyme, O2 activation either involves a 2e(-) reduced Fe(III)-OOH intermediate or a 4e(-) reduced Fe(IV)═O intermediate. Nuclear resonance vibrational spectroscopy (NRVS) has provided the geometric structure of these intermediates, and magnetic circular dichroism (MCD) has defined the frontier molecular orbitals (FMOs), the electronic structure that controls reactivity. This Account emphasizes that experimental spectroscopy is critical in evaluating the results of electronic structure calculations. Therefore these data are a key mechanistic bridge between structure and reactivity. For the Fe(III)-OOH intermediates, the anticancer drug activated bleomycin (BLM) acts as the non-heme Fe analog of compound 0 in heme (e.g., P450) chemistry. However BLM shows different reactivity: the low-spin (LS) Fe(III)-OOH can directly abstract a H atom from DNA. The LS and high-spin (HS) Fe(III)-OOHs have fundamentally different transition states. The LS transition state goes through a hydroxyl radical, but the HS transition state is activated for

  6. A novel non-heme iron-containing dioxygenase. Chloridazon-catechol dioxygenase from Phenylobacterium immobilis DSM 1986.

    Science.gov (United States)

    Müller, R; Schmitt, S; Lingens, F

    1982-07-01

    Previously we purified an enzyme from Phenylobacterium immobilis DSM 1986, which cleaves the catechol derivative of the herbicide Chloridazon [5-amino-4-chloro-2-phenyl-3 (2H)-pyridazinone] in the meta position. The enzyme, which could be crystallized, proved in Ouchterlony double-diffusion tests to consist of a single protein species. No cross-reaction was observed with other meta-cleaving enzymes. Its light absorption spectrum showed a maximum at 279 nm (epsilon = 310 mM -1 cm -1), shoulders at 289 nm and 275 nm and a very weak band at around 430 nm (epsilon = 1.14 mM -1 cm -1). The amino acid analysis showed a slight excess of acidic amino acids, in agreement with the pl of 4.5. Surprisingly the enzyme per se is completely inactive, although it contains one non-dialysable iron atom per submit. It has to be activated by preincubation with ferrous ions or ascorbate. The enzyme activated this way is autoxidizable and returns to its non-activated state in the presence of oxygen. During the reaction with the substrate, this inactivation seems to be enhanced about 100 times. Since this kind of activation and inactivation is not observed in other meta-cleaving enzymes, this enzyme seems to represent a new type of a non-heme iron dioxygenase. We tentatively propose the name Chloridazon-catechol dioxygenase for this enzyme.

  7. Non-heme induction of heme oxygenase-1 does not alter cellular iron metabolism.

    Science.gov (United States)

    Sheftel, Alex D; Kim, Sangwon F; Ponka, Prem

    2007-04-06

    The catabolism of heme is carried out by members of the heme oxygenase (HO) family. The products of heme catabolism by HO-1 are ferrous iron, biliverdin (subsequently converted to bilirubin), and carbon monoxide. In addition to its function in the recycling of hemoglobin iron, this microsomal enzyme has been shown to protect cells in various stress models. Implicit in the reports of HO-1 cytoprotection to date are its effects on the cellular handling of heme/iron. However, the limited amount of uncommitted heme in non-erythroid cells brings to question the source of substrate for this enzyme in non-hemolytic circumstances. In the present study, HO-1 was induced by either sodium arsenite (reactive oxygen species producer) or hemin or overexpressed in the murine macrophage-like cell line, RAW 264.7. Both of the inducers elicited an increase in active HO-1; however, only hemin exposure caused an increase in the synthesis rate of the iron storage protein, ferritin. This effect of hemin was the direct result of the liberation of iron from heme by HO. Cells stably overexpressing HO-1, although protected from oxidative stress, did not display elevated basal ferritin synthesis. However, these cells did exhibit an increase in ferritin synthesis, compared with untransfected controls, in response to hemin treatment, suggesting that heme levels, and not HO-1, limit cellular heme catabolism. Our results suggest that the protection of cells from oxidative insult afforded by HO-1 is not due to the catabolism of significant amounts of cellular heme as thought previously.

  8. Mononuclear non-heme iron enzymes with the 2-His-1-carboxylate facial triad: recent developments in enzymology and modeling studies.

    Science.gov (United States)

    Bruijnincx, Pieter C A; van Koten, Gerard; Klein Gebbink, Robertus J M

    2008-12-01

    Iron-containing enzymes are one of Nature's main means of effecting key biological transformations. The mononuclear non-heme iron oxygenases and oxidases have received the most attention recently, primarily because of the recent availability of crystal structures of many different enzymes and the stunningly diverse oxidative transformations that these enzymes catalyze. The wealth of available structural data has furthermore established the so-called 2-His-1-carboxylate facial triad as a new common structural motif for the activation of dioxygen. This superfamily of mononuclear iron(ii) enzymes catalyzes a wide range of oxidative transformations, ranging from the cis-dihydroxylation of arenes to the biosynthesis of antibiotics such as isopenicillin and fosfomycin. The remarkable scope of oxidative transformations seems to be even broader than that associated with oxidative heme enzymes. Not only are many of these oxidative transformations of key biological importance, many of these selective oxidations are also unprecedented in synthetic organic chemistry. In this critical review, we wish to provide a concise background on the chemistry of the mononuclear non-heme iron enzymes characterized by the 2-His-1-carboxylate facial triad and to discuss the many recent developments in the field. New examples of enzymes with unique reactivities belonging to the superfamily have been reported. Furthermore, key insights into the intricate mechanistic details and reactive intermediates have been obtained from both enzyme and modeling studies. Sections of this review are devoted to each of these subjects, i.e. the enzymes, biomimetic models, and reactive intermediates (225 references).

  9. Heme versus non-heme iron-nitroxyl {FeN(H)O}⁸ complexes: electronic structure and biologically relevant reactivity.

    Science.gov (United States)

    Speelman, Amy L; Lehnert, Nicolai

    2014-04-15

    Researchers have completed extensive studies on heme and non-heme iron-nitrosyl complexes, which are labeled {FeNO}(7) in the Enemark-Feltham notation, but they have had very limited success in producing corresponding, one-electron reduced, {FeNO}(8) complexes where a nitroxyl anion (NO(-)) is formally bound to an iron(II) center. These complexes, and their protonated iron(II)-NHO analogues, are proposed key intermediates in nitrite (NO2(-)) and nitric oxide (NO) reducing enzymes in bacteria and fungi. In addition, HNO is known to have a variety of physiological effects, most notably in the cardiovascular system. HNO may also serve as a signaling molecule in mammals. For these functions, iron-containing proteins may mediate the production of HNO and serve as receptors for HNO in vivo. In this Account, we highlight recent key advances in the preparation, spectroscopic characterization, and reactivity of ferrous heme and non-heme nitroxyl (NO(-)/HNO) complexes that have greatly enhanced our understanding of the potential biological roles of these species. Low-spin (ls) heme {FeNO}(7) complexes (S = 1/2) can be reversibly reduced to the corresponding {FeNO}(8) species, which are stable, diamagnetic compounds. Because the reduction is ligand (NO) centered in these cases, it occurs at extremely negative redox potentials that are at the edge of the biologically feasible range. Interestingly, the electronic structures of ls-{FeNO}(7) and ls-{FeNO}(8) species are strongly correlated with very similar frontier molecular orbitals (FMOs) and thermodynamically strong Fe-NO bonds. In contrast, high-spin (hs) non-heme {FeNO}(7) complexes (S = 3/2) can be reduced at relatively mild redox potentials. Here, the reduction is metal-centered and leads to a paramagnetic (S = 1) {FeNO}(8) complex. The increased electron density at the iron center in these species significantly decreases the covalency of the Fe-NO bond, making the reduced complexes highly reactive. In the absence of

  10. Synthesis of 5-hydroxyectoine from ectoine: crystal structure of the non-heme iron(II and 2-oxoglutarate-dependent dioxygenase EctD.

    Directory of Open Access Journals (Sweden)

    Klaus Reuter

    Full Text Available As a response to high osmolality, many microorganisms synthesize various types of compatible solutes. These organic osmolytes aid in offsetting the detrimental effects of low water activity on cell physiology. One of these compatible solutes is ectoine. A sub-group of the ectoine producer's enzymatically convert this tetrahydropyrimidine into a hydroxylated derivative, 5-hydroxyectoine. This compound also functions as an effective osmostress protectant and compatible solute but it possesses properties that differ in several aspects from those of ectoine. The enzyme responsible for ectoine hydroxylation (EctD is a member of the non-heme iron(II-containing and 2-oxoglutarate-dependent dioxygenases (EC 1.14.11. These enzymes couple the decarboxylation of 2-oxoglutarate with the formation of a high-energy ferryl-oxo intermediate to catalyze the oxidation of the bound organic substrate. We report here the crystal structure of the ectoine hydroxylase EctD from the moderate halophile Virgibacillus salexigens in complex with Fe(3+ at a resolution of 1.85 A. Like other non-heme iron(II and 2-oxoglutarate dependent dioxygenases, the core of the EctD structure consists of a double-stranded beta-helix forming the main portion of the active-site of the enzyme. The positioning of the iron ligand in the active-site of EctD is mediated by an evolutionarily conserved 2-His-1-carboxylate iron-binding motif. The side chains of the three residues forming this iron-binding site protrude into a deep cavity in the EctD structure that also harbours the 2-oxoglutarate co-substrate-binding site. Database searches revealed a widespread occurrence of EctD-type proteins in members of the Bacteria but only in a single representative of the Archaea, the marine crenarchaeon Nitrosopumilus maritimus. The EctD crystal structure reported here can serve as a template to guide further biochemical and structural studies of this biotechnologically interesting enzyme family.

  11. Synthesis of 5-hydroxyectoine from ectoine: crystal structure of the non-heme iron(II) and 2-oxoglutarate-dependent dioxygenase EctD.

    Science.gov (United States)

    Reuter, Klaus; Pittelkow, Marco; Bursy, Jan; Heine, Andreas; Craan, Tobias; Bremer, Erhard

    2010-05-14

    As a response to high osmolality, many microorganisms synthesize various types of compatible solutes. These organic osmolytes aid in offsetting the detrimental effects of low water activity on cell physiology. One of these compatible solutes is ectoine. A sub-group of the ectoine producer's enzymatically convert this tetrahydropyrimidine into a hydroxylated derivative, 5-hydroxyectoine. This compound also functions as an effective osmostress protectant and compatible solute but it possesses properties that differ in several aspects from those of ectoine. The enzyme responsible for ectoine hydroxylation (EctD) is a member of the non-heme iron(II)-containing and 2-oxoglutarate-dependent dioxygenases (EC 1.14.11). These enzymes couple the decarboxylation of 2-oxoglutarate with the formation of a high-energy ferryl-oxo intermediate to catalyze the oxidation of the bound organic substrate. We report here the crystal structure of the ectoine hydroxylase EctD from the moderate halophile Virgibacillus salexigens in complex with Fe(3+) at a resolution of 1.85 A. Like other non-heme iron(II) and 2-oxoglutarate dependent dioxygenases, the core of the EctD structure consists of a double-stranded beta-helix forming the main portion of the active-site of the enzyme. The positioning of the iron ligand in the active-site of EctD is mediated by an evolutionarily conserved 2-His-1-carboxylate iron-binding motif. The side chains of the three residues forming this iron-binding site protrude into a deep cavity in the EctD structure that also harbours the 2-oxoglutarate co-substrate-binding site. Database searches revealed a widespread occurrence of EctD-type proteins in members of the Bacteria but only in a single representative of the Archaea, the marine crenarchaeon Nitrosopumilus maritimus. The EctD crystal structure reported here can serve as a template to guide further biochemical and structural studies of this biotechnologically interesting enzyme family.

  12. Effects of proton acceptors on formation of a non-heme iron(IV)-oxo complex via proton-coupled electron transfer.

    Science.gov (United States)

    Nishida, Yusuke; Morimoto, Yuma; Lee, Yong-Min; Nam, Wonwoo; Fukuzumi, Shunichi

    2013-03-18

    Rates of formation of a non-heme iron(IV)-oxo complex, [Fe(IV)(O)(N4Py)](2+) (N4Py = N,N-bis(2-pyridylmethyl)-N-bis(2-pyridyl)methylamine), via electron-transfer oxidation of [Fe(III)(OH)(N4Py)](2+) in acetonitrile (MeCN) containing H2O (0.56 M) were accelerated as much as 390-fold by addition of proton acceptors such as CF3COO(-), TsO(-) (p-MeC6H4SO3(-)), NsO(-) (o-NO2C6H4SO3(-)), DNsO(-) (2,4-(NO2)2C6H3SO3(-)), and TfO(-) (CF3SO3(-)). The acceleration effect of proton acceptors increases with increasing basicity of the proton acceptors. The one-electron oxidation potential of [Fe(III)(OH)(N4Py)](2+) was shifted from 1.24 to 0.96 V vs SCE in the presence of TsO(-) (10 mM). The electron-transfer oxidation of Fe(III)-OH complex was coupled with the deprotonation process by proton acceptors in which deuterium kinetic isotope effects were observed when H2O was replaced by D2O.

  13. Catalytic Oxidation with a Non-Heme Iron Complex That Generates a Low-Spin FeIIIOOH Intermediate

    NARCIS (Netherlands)

    Roelfes, Gerard; Lubben, Marcel; Hage, Ronald; Que, Jr.; Feringa, Bernard

    2000-01-01

    The antitumor drug bleomycin (BLM) is proposed to act via a low-spin iron(III) hydroperoxide intermediate called “activated bleomycin”. To gain more insight into the mechanistic aspects of catalytic oxidation by these intermediates we have studied the reactivity of [(N4Py)Fe(CH3CN)](ClO4)2 (1) (N4Py

  14. Influence of Ligand Architecture in Tuning Reaction Bifurcation Pathways for Chlorite Oxidation by Non-Heme Iron Complexes

    NARCIS (Netherlands)

    Barman, Prasenjit; Faponle, Abayomi S; Vardhaman, Anil Kumar; Angelone, Davide; Löhr, Anna-Maria; Browne, Wesley R; Comba, Peter; Sastri, Chivukula V; de Visser, Sam P

    2016-01-01

    Reaction bifurcation processes are often encountered in the oxidation of substrates by enzymes and generally lead to a mixture of products. One particular bifurcation process that is common in biology relates to electron transfer versus oxygen atom transfer by high-valent iron(IV)-oxo complexes, whi

  15. Novel Three-Component Rieske Non-Heme Iron Oxygenase System Catalyzing the N-Dealkylation of Chloroacetanilide Herbicides in Sphingomonads DC-6 and DC-2

    Science.gov (United States)

    Chen, Qing; Wang, Cheng-Hong; Deng, Shi-Kai; Wu, Ya-Dong; Li, Yi; Yao, Li; Jiang, Jian-Dong; Yan, Xin; Li, Shun-Peng

    2014-01-01

    Sphingomonads DC-6 and DC-2 degrade the chloroacetanilide herbicides alachlor, acetochlor, and butachlor via N-dealkylation. In this study, we report a three-component Rieske non-heme iron oxygenase (RHO) system catalyzing the N-dealkylation of these herbicides. The oxygenase component gene cndA is located in a transposable element that is highly conserved in the two strains. CndA shares 24 to 42% amino acid sequence identities with the oxygenase components of some RHOs that catalyze N- or O-demethylation. Two putative [2Fe-2S] ferredoxin genes and one glutathione reductase (GR)-type reductase gene were retrieved from the genome of each strain. These genes were not located in the immediate vicinity of cndA. The four ferredoxins share 64 to 72% amino acid sequence identities to the ferredoxin component of dicamba O-demethylase (DMO), and the two reductases share 62 to 65% amino acid sequence identities to the reductase component of DMO. cndA, the four ferredoxin genes, and the two reductases genes were expressed in Escherichia coli, and the recombinant proteins were purified using Ni-affinity chromatography. The individual components or the components in pairs displayed no activity; the enzyme mixture showed N-dealkylase activities toward alachlor, acetochlor, and butachlor only when CndA-His6 was combined with one of the four ferredoxins and one of the two reductases, suggesting that the enzyme consists of three components, a homo-oligomer oxygenase, a [2Fe-2S] ferredoxin, and a GR-type reductase, and CndA has a low specificity for the electron transport component (ETC). The N-dealkylase utilizes NADH, but not NADPH, as the electron donor. PMID:24928877

  16. End-on and side-on peroxo derivatives of non-heme iron complexes with pentadentate ligands : Models for putative intermediates in biological iron/dioxygen chemistry

    NARCIS (Netherlands)

    Roelfes, G; Vrajmasu, [No Value; Ho, RYN; Rohde, JU; Zondervan, C; la Crois, RM; Schudde, EP; Lutz, M; Spek, AL; Hage, R; Feringa, BL; Munck, E; Que, L; Vrajmasu, Vladislav; Ho, Raymond Y.N.; Rohde, Jan-Uwe; Crois, Rene M. la; Spek, Anthony L.; Que, Jr.; Feringa, Bernard

    2003-01-01

    Mononuclear iron(III) species with end-on and side-on peroxide have been proposed or identified in the catalytic cycles of the antitumor drug bleomycin and a variety of enzymes, such as cytochrome P450 and Rieske dioxygenases, Only recently have biomimetic analogues of such reactive species been, ge

  17. A comparative DFT study of oxygen reduction reaction on mononuclear and binuclear cobalt and iron phthalocyanines

    Science.gov (United States)

    Chen, Xin; Li, Mengke; Yu, Zongxue; Ke, Qiang

    2016-12-01

    The oxygen reduction reaction (ORR) catalyzed by mononuclear and planar binuclear cobalt (CoPc) and iron phthalocyanine (FePc) catalysts is investigated in detail by density functional theory (DFT) methods. The calculation results indicate that the ORR activity of Fe-based Pcs is much higher than that of Co-based Pcs, which is due to the fact that the former could catalyze 4e- ORRs, while the latter could catalyze only 2e- ORRs from O2 to H2O2. The original high activities of Fe-based Pcs could be attributed to their high energy level of the highest occupied molecular orbital (HOMO), which could lead to the stronger adsorption energy between catalysts and ORR species. Nevertheless, the HOMO of Co-based Pcs is the ring orbital, not the 3 d Co orbital, thereby inhibiting the electron transfer from metal to adsorbates. Furthermore, compared with mononuclear FePc, the planar binuclear FePc has more stable structure in acidic medium and more suitable adsorption energy of ORR species, making it a promising non-precious electrocatalyst for ORR.

  18. Inhibitory effect of calcium on non-heme iron absorption may be related to translocation of DMT-1 at the apical membrane of enterocytes.

    Science.gov (United States)

    Thompson, Ben A V; Sharp, Paul A; Elliott, Ruan; Fairweather-Tait, Susan J

    2010-07-28

    Many studies show that calcium reduces iron absorption from single meals, but the underlying mechanism is not known. We tested the hypothesis that calcium alters the expression and/or functionality of iron transport proteins. Differentiated Caco-2 cells were treated with ferric ammonium citrate and calcium chloride, and ferritin, DMT-1, and ferroportin were quantified in whole-cell lysate and cell-membrane fractions. Calcium attenuated the iron-induced increase in cell ferritin levels in a dose-dependent manner; a significant decrease was seen at calcium concentrations of 1.25 and 2.5 mM but was only evident after a 16-24 h incubation period. Calcium and iron treatments decreased DMT-1 protein in Caco-2 cell membranes, although total DMT-1 in whole cell lysates was unchanged by either iron or calcium. No change was seen in ferroportin expression. Our data suggest that calcium reduces iron bioavailability by decreasing DMT-1 expression at the apical cell membrane, thereby downregulating iron transport into the cell.

  19. Influence of Cd{sup 2+} on the spin state of non-heme iron and on protein local motions in reactions centers from purple photosynthetic bacterium Rhodospirilium rubrum

    Energy Technology Data Exchange (ETDEWEB)

    Lipinska, M [Institute of Nuclear Physics PAN, 31-342 Krakow, Radzikowskiego 152 (Poland); Orzechowska, A [Institute of Physics, Jagiellonian University, 30-059 Krakow, Reymonta 4 (Poland); Fiedor, J; Slezak, T; Zajac, M; Matlak, K; Korecki, J; Halas, A; Burda, K [Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, 30-059 Krakow, Reymonta 19 (Poland); Chumakov, A I [European Synchrotron Radiation Facility, BP220, F-38043 Grenoble Cedex (France); Strzalka, K; Fiedor, L, E-mail: burda@novell.ftj.agh.edu.p [Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, 30-387 Krakow, Gronostajowa 7 (Poland)

    2010-03-01

    Non-heme Fe is a conservative component of the Q-type photosynthetic reaction centers but its function remains unknown. Applying Moessbauer spectroscopy we show that in Rhodospirillum rubrum the non-heme Fe exists mostly in a ferrous low spin state. The binding of Cd{sup 2+} ions in the vicinity of the quinone-Fe complex changes the high spin state of the non-heme Fe into a low spin one characterized by hyperfine parameters similar to those obtained for the non-heme Fe low spin state in untreated reaction centers, as confirmed by Moessbauer measurements. The nuclear inelastic scattering of synchrotron radiation experiments show that the contribution of vibrations at low energies, between 3-15 meV, activated at 240 K are damped in the bacterial reaction centers treated with CdCl{sub 2}. No influence of Cd{sup 2+} ions is observed on the soft vibrational states at 60 K. These results suggest that binding of cadmium cations within the reaction centers may enhance decoupling of the non-heme Fe from the surrounding protein matrix at temperatures higher than 200 K, what can explain the slowing down of electron transfer between the Q{sub A} and Q{sub B} quinones by Cd{sup 2+}.

  20. Oxygen-independent alkane formation by non-heme iron-dependent cyanobacterial aldehyde decarbonylase: investigation of kinetics and requirement for an external electron donor.

    Science.gov (United States)

    Eser, Bekir E; Das, Debasis; Han, Jaehong; Jones, Patrik R; Marsh, E Neil G

    2011-12-13

    Cyanobacterial aldehyde decarbonylase (cAD) is, structurally, a member of the di-iron carboxylate family of oxygenases. We previously reported that cAD from Prochlorococcus marinus catalyzes the unusual hydrolysis of aldehydes to produce alkanes and formate in a reaction that requires an external reducing system but does not require oxygen [Das et al. (2011) Angew. Chem. 50, 7148-7152]. Here we demonstrate that cADs from divergent cyanobacterial classes, including the enzyme from N. puntiformes that was reported to be oxygen dependent, catalyze aldehyde decarbonylation at a much faster rate under anaerobic conditions and that the oxygen in formate derives from water. The very low activity (<1 turnover/h) of cAD appears to result from inhibition by the ferredoxin reducing system used in the assay and the low solubility of the substrate. Replacing ferredoxin with the electron mediator phenazine methosulfate allowed the enzyme to function with various chemical reductants, with NADH giving the highest activity. NADH is not consumed during turnover, in accord with the proposed catalytic role for the reducing system in the reaction. With octadecanal, a burst phase of product formation, k(prod) = 3.4 ± 0.5 min(-1), is observed, indicating that chemistry is not rate-determining under the conditions of the assay. With the more soluble substrate, heptanal, k(cat) = 0.17 ± 0.01 min(-1) and no burst phase is observed, suggesting that a chemical step is limiting in the reaction of this substrate.

  1. Mechanistic insights on the ortho-hydroxylation of aromatic compounds by non-heme iron complex: a computational case study on the comparative oxidative ability of ferric-hydroperoxo and high-valent Fe(IV)═O and Fe(V)═O intermediates.

    Science.gov (United States)

    Ansari, Azaj; Kaushik, Abhishek; Rajaraman, Gopalan

    2013-03-20

    ortho-Hydroxylation of aromatic compounds by non-heme Fe complexes has been extensively studied in recent years by several research groups. The nature of the proposed oxidant varies from Fe(III)-OOH to high-valent Fe(IV)═O and Fe(V)═O species, and no definitive consensus has emerged. In this comprehensive study, we have investigated the ortho-hydroxylation of aromatic compounds by an iron complex using hybrid density functional theory incorporating dispersion effects. Three different oxidants, Fe(III)-OOH, Fe(IV)═O, and Fe(V)═O, and two different pathways, H-abstraction and electrophilic attack, have been considered to test the oxidative ability of different oxidants and to underpin the exact mechanism of this regiospecific reaction. By mapping the potential energy surface of each oxidant, our calculations categorize Fe(III)-OOH as a sluggish oxidant, as both proximal and distal oxygen atoms of this species have prohibitively high barriers to carry out the aromatic hydroxylation. This is in agreement to the experimental observation where Fe(III)-OOH is found not to directly attack the aromatic ring. A novel mechanism for the explicit generation of non-heme Fe(IV)═O and Fe(V)═O from isomeric forms of Fe(III)-OOH has been proposed where the O···O bond is found to cleave via homolytic (Fe(IV)═O) or heterolytic (Fe(V)═O) fashion exclusively. Apart from having favorable formation energies, the Fe(V)═O species also has a lower barrier height compared to the corresponding Fe(IV)═O species for the aromatic ortho-hydroxylation reaction. The transient Fe(V)═O prefers electrophilic attack on the benzene ring rather than the usual aromatic C-H activation step. A large thermodynamic drive for the formation of a radical intermediate is encountered in the mechanistic scene, and this intermediate substantially diminishes the energy barrier required for C-H activation by the Fe(V)═O species. Further spin density distribution and the frontier orbitals of

  2. Mononuclear non-heme iron(III) complexes of linear and tripodal tridentate ligands as functional models for catechol dioxygenases: Effect of -alkyl substitution on regioselectivity and reaction rate

    Indian Academy of Sciences (India)

    Mallayan Palaniandavar; Kusalendiran Visvaganesan

    2011-03-01

    Catechol dioxygenases are responsible for the last step in the biodegradation of aromatic molecules in the environment. The iron(II) active site in the extradiol-cleaving enzymes cleaves the C-C bond adjacent to the hydroxyl group, while the iron(III) active site in the intradiol-cleaving enzymes cleaves the C-C bond in between two hydroxyl groups. A series of mononuclear iron(III) complexes of the type [Fe(L)Cl3], where L is the linear -alkyl substituted bis(pyrid-2-ylmethyl)amine, -alkyl substituted -(pyrid-2-ylmethyl)ethylenediamine, linear tridentate 3N ligands containing imidazolyl moieties and tripodal ligands containing pyrazolyl moieties have been isolated and studied as structural and functional models for catechol dioxygenase enzymes. All the complexes catalyse the cleavage of catechols using molecular oxygen to afford both intra- and extradiol cleavage products. The rate of oxygenation depends on the solvent and the Lewis acidity of iron(III) center as modified by the sterically demanding -alkyl groups. Also, our studies reveal that stereo-electronic factors like the Lewis acidity of the iron(III) center and the steric demand of ligands, as regulated by the -alkyl substituents, determine the regioselectivity and the rate of dioxygenation. In sharp contrast to all these complexes, the pyrazole-containing tripodal ligand complexes yield mainly the oxidized product benzoquinone.

  3. Reversible dissociation and ligand-glutathione exchange reaction in binuclear cationic tetranitrosyl iron complex with penicillamine.

    Science.gov (United States)

    Syrtsova, Lidia; Sanina, Natalia; Lyssenko, Konstantin; Kabachkov, Evgeniy; Psikha, Boris; Shkondina, Natal'ja; Pokidova, Olesia; Kotelnikov, Alexander; Aldoshin, Sergey

    2014-01-01

    This paper describes a comparative study of the decomposition of two nitrosyl iron complexes (NICs) with penicillamine thiolic ligands [Fe2(SC5H11NO2)2(NO)4]SO4 ·5H2O (I) and glutathione- (GSH-) ligands [Fe2(SC10H17N3O6)2(NO)4]SO4 ·2H2O (II), which spontaneously evolve to NO in aqueous medium. NO formation was measured by a sensor electrode and by spectrophotometric methods by measuring the formation of a hemoglobin- (Hb-) NO complex. The NO evolution reaction rate from (I)  k 1 = (4.6 ± 0.1)·10(-3) s(-1) and the elimination rate constant of the penicillamine ligand k 2 = (1.8 ± 0.2)·10(-3) s(-1) at 25°C in 0.05 M phosphate buffer,  pH 7.0, was calculated using kinetic modeling based on the experimental data. Both reactions are reversible. Spectrophotometry and mass-spectrometry methods have firmly shown that the penicillamine ligand is exchanged for GS(-) during decomposition of 1.5·10(-4) M (I) in the presence of 10(-3) M GSH, with 76% yield in 24 h. As has been established, such behaviour is caused by the resistance of (II) to decomposition due to the higher affinity of iron to GSH in the complex. The discovered reaction may impede S-glutathionylation of the essential enzyme systems in the presence of (I) and is important for metabolism of NIC, connected with its antitumor activity.

  4. Synthesis, Structure and Characterization of a Novel Asymmetrical Half-sandwich Binuclear Iron Carborane Complex [η5-C5H3(t-Bu)2]2Fe2(CO)3Se2C2B10H10

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Halfsandwich iron dicarbonyl complex [η5-C5H3(t-Bu)2]Fe(CO)2Cl(1) reacts with 1, 2-dilithium diseleno carborane Li2Se2C2B10H10(2) to give a binuclear iron carborane complex [η5-C5H3(t-Bu)2]2Fe2(CO)3*Se2C2B10H10(3). The X-ray diffraction analysis of complex 3 reveals that one of the iron atoms is chiral.

  5. Engineering Non-Heme Mono- and Dioxygenases for Biocatalysis

    Directory of Open Access Journals (Sweden)

    Adi Dror

    2012-09-01

    Full Text Available Oxygenases are ubiquitous enzymes that catalyze the introduction of one or two oxygen atoms to unreactive chemical compounds. They require reduction equivalents from NADH or NADPH and comprise metal ions, metal ion complexes, or coenzymes in their active site. Thus, for industrial purposes, oxygenases are most commonly employed using whole cell catalysis, to alleviate the need for co-factor regeneration. Biotechnological applications include bioremediation, chiral synthesis, biosensors, fine chemicals, biofuels, pharmaceuticals, food ingredients and polymers. Controlling activity and selectivity of oxygenases is therefore of great importance and of growing interest to the scientific community. This review focuses on protein engineering of non-heme monooxygenases and dioxygenases for generating improved or novel functionalities. Rational mutagenesis based on x-ray structures and sequence alignment, as well as random methods such as directed evolution, have been utilized. It is concluded that knowledge-based protein engineering accompanied with targeted libraries, is most efficient for the design and tuning of biocatalysts towards novel substrates and enhanced catalytic activity while minimizing the screening efforts.

  6. Spin crossover and polymorphism in a family of 1,2-bis(4-pyridyl)ethene-bridged binuclear iron(II) complexes. A key role of structural distortions.

    Science.gov (United States)

    Matouzenko, Galina S; Jeanneau, Erwann; Verat, Alexander Yu; Bousseksou, Azzedine

    2011-10-07

    Two polymorphic modifications 1 and 3 of binuclear compound [{Fe(dpia)(NCS)(2)}(2)(bpe)] and pseudo-polymorphic modification [{Fe(dpia)(NCS)(2)}(2)(bpe)]·2CH(3)OH (2), where dpia = di-(2-picolyl)amine, bpe = 1,2-bis(4-pyridyl)ethene, were synthesized, and their structures, magnetic properties, and Mössbauer spectra were studied. Variable-temperature magnetic susceptibility measurements of three binuclear compounds show different types of magnetic behaviour. The complex 1 exhibits a gradual two-step spin crossover (SCO) suggesting the occurrence of the mixed [HS-LS] (HS: high spin, LS: low spin) pair at the plateau temperature (182 K), at which about 50% of the complexes undergoes a thermal spin conversion. The complex 2 displays an abrupt full one-step spin transition without hysteresis, centred at about 159 K. The complex 3 is paramagnetic over the temperature range 20-290 K. The single-crystal X-ray studies show that all three compounds are built up from the bpe-bridged binuclear molecules. The structure of 1 was solved for three spin isomers [HS-HS], [HS-LS], and [LS-LS] at three temperatures 300 K, 183 K, and 90 K. The crystal structures for 2 and 3 were determined for the [HS-HS] complexes at room temperature. The analysis of correlations between the structural characteristics and different types of magnetic behaviour for new 1-3 binuclear complexes, as well as for previously reported binuclear compounds, revealed that the SCO process (occurrence of full one-step, two-step, or partial (50%) SCO) is specified by the degree of distortion of the octahedral geometry of the [FeN(6)] core, caused by both packing and strain effects arising from terminal and/or bridging ligands. The comparison of the magnetic properties and the networks of intra- and inter-molecular interactions in the crystal lattice for the family of related SCO binuclear compounds suggests that the intermolecular interactions play a predominant role in the cooperativeness of the spin transition

  7. Non-heme iron oxygenases generate natural structural diversity in carbapenem antibiotics.

    Science.gov (United States)

    Bodner, Micah J; Phelan, Ryan M; Freeman, Michael F; Li, Rongfeng; Townsend, Craig A

    2010-01-13

    Carbapenems are a clinically important antibiotic family. More than 50 naturally occurring carbapenam/ems are known and are distinguished primarily by their C-2/C-6 side chains where many are only differentiated by the oxidation states of these substituents. With a limited palette of variations the carbapenem family comprises a natural combinatorial library, and C-2/C-6 oxidation is associated with increased efficacy. We demonstrate that ThnG and ThnQ encoded by the thienamycin gene cluster in Streptomyces cattleya oxidize the C-2 and C-6 moieties of carbapenems, respectively. ThnQ stereospecifically hydroxylates PS-5 (5) giving N-acetyl thienamycin (2). ThnG catalyzes sequential desaturation and sulfoxidation of PS-5 (5), giving PS-7 (7) and its sulfoxide (9). The enzymes are relatively substrate selective but are proposed to give rise to the oxidative diversity of carbapenems produced by S. cattleya, and orthologues likely function similarly in allied streptomyces. Elucidating the roles of ThnG and ThnQ will focus further investigations of carbapenem antibiotic biosynthesis.

  8. Assignment of Soret MLCT band of reduced form of copper binuclear cluster in cytochrome c oxidase film

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Low concentration of dithionite results in the reduction of Cu-Cu binuclear and heme a active sites of the cytochrome c oxidase thin solid film immersed in the acidic phosphate buffer, but Fe-Cu binuclear center keeps in the oxidation state. It manifests as a negative peak at 426 nm and a positive one at ~408 nm in the difference spectra induced by dithionite. The former implies decrease of the oxidized form of heme a center, that is, Fea3+→Fea2+. And the latter results from the contribution of metal-ligand charge transfer (MLCT) transition in the reduced binuclear Cu-Cu cluster, rather than from that of heme a center. This stronger Soret MLCT band must be helpful to overcoming the difficulty in distinguishing the weaker copper sign from the stronger one of iron when studying copper-iron protein.

  9. The "innocent" role of Sc3+ on a non-heme Fe catalyst in an O2 environment

    KAUST Repository

    Poater, Albert

    2014-01-01

    Density functional theory calculations have been used to investigate the reaction mechanism proposed for the formation of an oxoiron(iv) complex [Fe IV(TMC)O]2+ (P) (TMC = 1,4,8,11-tetramethylcyclam) starting from a non-heme reactant complex [FeII(TMC)]2+ (R) and O2 in the presence of acid H+ and reductant BPh4 -. We also addressed the possible role of redox-inactive Sc3+ as a replacement for H+ acid in this reaction to trigger the formation of P. Our computational results substantially confirm the proposed mechanism and, more importantly, support that Sc 3+ could trigger the O2 activation, mainly dictated by the availability of two electrons from BPh4 -, by forming a thermodynamically stable Sc3+-peroxo-Fe3+ core that facilitates O-O bond cleavage to generate P by reducing the energy barrier. These insights may pave the way to improve the catalytic reactivity of metal-oxo complexes in O2 activation at non-heme centers. This journal is © the Partner Organisations 2014.

  10. An autocatalytic radical chain pathway in formation of an iron(IV)-oxo complex by oxidation of an iron(II) complex with dioxygen and isopropanol.

    Science.gov (United States)

    Morimoto, Yuma; Lee, Yong-Min; Nam, Wonwoo; Fukuzumi, Shunichi

    2013-03-28

    Evidence of an autocatalytic radical chain pathway has been reported in formation of a non-heme iron(IV)-oxo complex by oxidation of an iron(II) complex with dioxygen and isopropanol in acetonitrile at 298 K. The radical chain reaction is initiated by hydrogen abstraction from isopropanol by the iron(IV)-oxo complex.

  11. Duodenal Cytochrome b (DCYTB in Iron Metabolism: An Update on Function and Regulation

    Directory of Open Access Journals (Sweden)

    Darius J. R. Lane

    2015-03-01

    Full Text Available Iron and ascorbate are vital cellular constituents in mammalian systems. The bulk-requirement for iron is during erythropoiesis leading to the generation of hemoglobin-containing erythrocytes. Additionally; both iron and ascorbate are required as co-factors in numerous metabolic reactions. Iron homeostasis is controlled at the level of uptake; rather than excretion. Accumulating evidence strongly suggests that in addition to the known ability of dietary ascorbate to enhance non-heme iron absorption in the gut; ascorbate regulates iron homeostasis. The involvement of ascorbate in dietary iron absorption extends beyond the direct chemical reduction of non-heme iron by dietary ascorbate. Among other activities; intra-enterocyte ascorbate appears to be involved in the provision of electrons to a family of trans-membrane redox enzymes; namely those of the cytochrome b561 class. These hemoproteins oxidize a pool of ascorbate on one side of the membrane in order to reduce an electron acceptor (e.g., non-heme iron on the opposite side of the membrane. One member of this family; duodenal cytochrome b (DCYTB; may play an important role in ascorbate-dependent reduction of non-heme iron in the gut prior to uptake by ferrous-iron transporters. This review discusses the emerging relationship between cellular iron homeostasis; the emergent “IRP1-HIF2α axis”; DCYTB and ascorbate in relation to iron metabolism.

  12. Redox-inactive metal ions promoted the catalytic reactivity of non-heme manganese complexes towards oxygen atom transfer.

    Science.gov (United States)

    Choe, Cholho; Yang, Ling; Lv, Zhanao; Mo, Wanling; Chen, Zhuqi; Li, Guangxin; Yin, Guochuan

    2015-05-21

    Redox-inactive metal ions can modulate the reactivity of redox-active metal ions in a variety of biological and chemical oxidations. Many synthetic models have been developed to help address the elusive roles of these redox-inactive metal ions. Using a non-heme manganese(II) complex as the model, the influence of redox-inactive metal ions as a Lewis acid on its catalytic efficiency in oxygen atom transfer was investigated. In the absence of redox-inactive metal ions, the manganese(II) catalyst is very sluggish, for example, in cyclooctene epoxidation, providing only 9.9% conversion with 4.1% yield of epoxide. However, addition of 2 equiv. of Al(3+) to the manganese(II) catalyst sharply improves the epoxidation, providing up to 97.8% conversion with 91.4% yield of epoxide. EPR studies of the manganese(II) catalyst in the presence of an oxidant reveal a 16-line hyperfine structure centered at g = 2.0, clearly indicating the formation of a mixed valent di-μ-oxo-bridged diamond core, Mn(III)-(μ-O)2-Mn(IV). The presence of a Lewis acid like Al(3+) causes the dissociation of this diamond Mn(III)-(μ-O)2-Mn(IV) core to form monomeric manganese(iv) species which is responsible for improved epoxidation efficiency. This promotional effect has also been observed in other manganese complexes bearing various non-heme ligands. The findings presented here have provided a promising strategy to explore the catalytic reactivity of some di-μ-oxo-bridged complexes by adding non-redox metal ions to in situ dissociate those dimeric cores and may also provide clues to understand the mechanism of methane monooxygenase which has a similar diiron diamond core as the intermediate.

  13. Non-heme manganese catalysts for on-demand production of chlorine dioxide in water and under mild conditions.

    Science.gov (United States)

    Hicks, Scott D; Kim, Doyeon; Xiong, Silei; Medvedev, Grigori A; Caruthers, James; Hong, Seungwoo; Nam, Wonwoo; Abu-Omar, Mahdi M

    2014-03-05

    Two non-heme manganese complexes are used in the catalytic formation of chlorine dioxide from chlorite under ambient temperature at pH 5.00. The catalysts afford up to 1000 turnovers per hour and remain highly active in subsequent additions of chlorite. Kinetic and spectroscopic studies revealed a Mn(III)(OH) species as the dominant form under catalytic conditions. A Mn(III)(μ-O)Mn(IV) dinuclear species was observed by EPR spectroscopy, supporting the involvement of a putative Mn(IV)(O) species. First-order kinetic dependence on the manganese catalyst precludes the dinuclear species as the active form of the catalyst. Quantitative kinetic modeling enabled the deduction of a mechanism that accounts for all experimental observations. The chlorine dioxide producing cycle involves formation of a putative Mn(IV)(O), which undergoes PCET (proton coupled electron-transfer) reaction with chlorite to afford chlorine dioxide. The ClO2 product can be efficiently removed from the aqueous reaction mixture via purging with an inert gas, allowing for the preparation of pure chlorine dioxide for on-site use and further production of chlorine dioxide.

  14. Iron accumulation with age, oxidative stress and functional decline.

    Directory of Open Access Journals (Sweden)

    Jinze Xu

    Full Text Available Identification of biological mediators in sarcopenia is pertinent to the development of targeted interventions to alleviate this condition. Iron is recognized as a potent pro-oxidant and a catalyst for the formation of reactive oxygen species in biological systems. It is well accepted that iron accumulates with senescence in several organs, but little is known about iron accumulation in muscle and how it may affect muscle function. In addition, it is unclear if interventions which reduced age-related loss of muscle quality, such as calorie restriction, impact iron accumulation. We investigated non-heme iron concentration, oxidative stress to nucleic acids in gastrocnemius muscle and key indices of sarcopenia (muscle mass and grip strength in male Fischer 344 X Brown Norway rats fed ad libitum (AL or a calorie restricted diet (60% of ad libitum food intake starting at 4 months of age at 8, 18, 29 and 37 months of age. Total non-heme iron levels in the gastrocnemius muscle of AL rats increased progressively with age. Between 29 and 37 months of age, the non-heme iron concentration increased by approximately 200% in AL-fed rats. Most importantly, the levels of oxidized RNA in gastrocnemius muscle of AL rats were significantly increased as well. The striking age-associated increase in non-heme iron and oxidized RNA levels and decrease in sarcopenia indices were all attenuated in the calorie restriction (CR rats. These findings strongly suggest that the age-related iron accumulation in muscle contributes to increased oxidative damage and sarcopenia, and that CR effectively attenuates these negative effects.

  15. Iron

    Science.gov (United States)

    Iron is a mineral that our bodies need for many functions. For example, iron is part of hemoglobin, a protein which carries ... It helps our muscles store and use oxygen. Iron is also part of many other proteins and ...

  16. Iron

    Science.gov (United States)

    ... of iron stored in the body become low, iron deficiency anemia sets in. Red blood cells become smaller and ... from the lungs throughout the body. Symptoms of iron deficiency anemia include tiredness and lack of energy, GI upset, ...

  17. Iron

    DEFF Research Database (Denmark)

    Hansen, Jakob Bondo; Moen, I W; Mandrup-Poulsen, T

    2014-01-01

    The interest in the role of ferrous iron in diabetes pathophysiology has been revived by recent evidence of iron as an important determinant of pancreatic islet inflammation and as a biomarker of diabetes risk and mortality. The iron metabolism in the β-cell is complex. Excess free iron is toxic......, but at the same time, iron is required for normal β-cell function and thereby glucose homeostasis. In the pathogenesis of diabetes, iron generates reactive oxygen species (ROS) by participating in the Fenton chemistry, which can induce oxidative damage and apoptosis. The aim of this review is to present...... and discuss recent evidence, suggesting that iron is a key pathogenic factor in both type 1 and type 2 diabetes with a focus on inflammatory pathways. Pro-inflammatory cytokine-induced β-cell death is not fully understood, but may include iron-induced ROS formation resulting in dedifferentiation by activation...

  18. Alteration by irradiation and storage at amount of heme iron in poultry meat; Alteracoes provocadas pela irradiacao e armazenamento nos teores de ferro heme em carne de frango

    Energy Technology Data Exchange (ETDEWEB)

    Souza, Adriana Regia Marques de; Arthur, Valter Arthur [Centro de Energia Nuclear na Agricultura (CENA), Piracicaba, SP (Brazil). Lab. de Irradiacao de Alimentos e Radioentomologia; Canniatti-Brazaca, Solange Guidolin [Escola Superior de Agricultura Luiz de Queiroz (ESALQ/USP), Piracicaba, SP (Brazil). Dept. de Agroindustria, Alimentos e Nutricao]. E-mail: sgcbraza@esalq.usp.br

    2007-04-15

    Studies of irradiation and storage effects in chicken were carried out to discover the influence in iron heme, non-heme amount, color and total pigments. Chicken thighs and chicken breast were studied. These were irradiated to 0, 1 and 2 kGy stored by 14 days to 4 deg C in refrigerator. Determining the heme content and non-heme of meat was done using the colorimeter method and the Ferrozine reagent. The values of iron heme were influenced both by the irradiation and the storage, reducing the amount throughout the course of time. The iron non-heme was also influenced by the doses and the storage time, however the values increased throughout the course of time, because of the conversion of iron heme in non-heme. The color did not show that it was influenced by the studied doses, except for the storage, and the total number of pigments was affected by the irradiation and the time, reducing the values with the increase of storage. Irradiation was shown to be a good method to conserve iron. (author)

  19. The Effects of Cereals and Legumes on Iron Availability.

    Science.gov (United States)

    1982-06-01

    INACG Secretariat, a task force of specialists fromvarious fields met with representatives of the federal government, academia and industry to review...and prevalence of nutritional anemia worldwide. In ful- industry to review recent research findings. This filling this mandate, INACG sponsors...carbonates, oxalates, phos- to cause a decrease in the percentage absorption of phates and phytates (Bothwell et al., 1979). Many non-heme iron, but the

  20. Spectroscopic and computational studies of NTBC bound to the non-heme iron enzyme (4-hydroxyphenyl)pyruvate dioxygenase: active site contributions to drug inhibition.

    Science.gov (United States)

    Neidig, Michael L; Decker, Andrea; Kavana, Michael; Moran, Graham R; Solomon, Edward I

    2005-12-01

    (4-Hydroxyphenyl)pyruvate dioxygenase (HPPD) is an alpha-keto-acid-dependent dioxygenase which catalyzes the conversion of (4-hydroxyphenyl)pyruvate (HPP) to homogentisate as part of tyrosine catabolism. While several di- and tri-ketone alkaloids are known as inhibitors of HPPD and used commercially as herbicides, one such inhibitor, [2-nitro-4-(trifluoromethyl)benzoyl]-1,3-cyclohexanedione (NTBC), has also been used therapeutically to treat type I tyrosinemia and alkaptonuria in humans. To gain further insight into the mechanism of inhibition by NTBC, a combination of CD/MCD spectroscopy and DFT calculations of HPPD/Fe(II)/NTBC has been performed to evaluate the contribution of the Fe(II)-NTBC bonding interaction to the high affinity of this drug for the enzyme. The results indicate that the bonding of NTBC to Fe(II) is very similar to that for HPP, both involving similar pi-backbonding interactions between NTBC/HPP and Fe(II). Combined with the result that the calculated binding energy of NTBC is, in fact, approximately 3 kcal/mol less than that for HPP, the bidentate coordination of NTBC to Fe(II) is not solely responsible for its extremely high affinity for the enzyme. Thus, the pi-stacking interactions between the aromatic rings of NTBC and two phenyalanine residues, as observed in the crystallography of the HPPD/Fe(II)/NTBC complex, appear to be responsible for the observed high affinity of drug binding.

  1. Hydrolytic activity of -alkoxide/acetato-bridged binuclear Cu(II) complexes towards carboxylic acid ester

    Indian Academy of Sciences (India)

    Weidong Jiang; Bin Xu; Zhen Xiang; Shengtian Huang; Fuan Liu; Ying Wang

    2013-09-01

    Two -alkoxide/acetate-bridged small molecule binuclear copper(II) complexes were synthesized, and used to promote the hydrolysis of a classic carboxylic acid ester, -nitrophenyl picolinate (PNPP). Both binuclear complexes exhibited good hydrolytic reactivity, giving rise to . 15547- and 17462-fold acceleration over background value for PNPP hydrolysis at neutral conditions, respectively. For comparing, activities of the other two mononuclear analogues were evaluated, revealing that binuclear complexes show approximately 150- and 171-fold kinetic advantage over their mononuclear analogues.

  2. Binuclear ruthenium(II) complexes for amyloid fibrils recognition

    Energy Technology Data Exchange (ETDEWEB)

    Hanczyc, Piotr, E-mail: piotr.hanczyc@chalmers.se

    2014-12-05

    Highlights: • Interactions of binuclear ruthenium(II) complexes with amyloid fibrils. • Dimer ruthenium(II) compounds are sensitive amyloid fibrils biomarkers. • Recognition of amyloid-chromophore adducts by two-photon excited emission. - Abstract: Metal–organic compounds represent a unique class of biomarkers with promising photophysical properties useful for imaging. Here interactions of insulin fibrils with two binuclear complexes [μ-(11,11′-bidppz)(phen){sub 4}Ru{sub 2}]{sup 4+} (1) and [μ-C4(cpdppz)(phen){sub 4}Ru{sub 2}]{sup 4+} (2) are studied by linear dichroism (LD) and fluorescence. These ruthenium(II) compounds could provide a new generation of amyloid binding chromophores with long lived lifetimes, good luminescence quantum yields for the bound molecules and photo-stability useful in multiphoton luminescence imaging.

  3. Biochemical and Spectroscopic Characterization of the Non-Heme Fe(II)- and 2-Oxoglutarate-Dependent Ethylene-Forming Enzyme from Pseudomonas syringae pv. phaseolicola PK2.

    Science.gov (United States)

    Martinez, Salette; Hausinger, Robert P

    2016-11-01

    The ethylene-forming enzyme (EFE) from Pseudomonas syringae pv. phaseolicola PK2 is a member of the mononuclear non-heme Fe(II)- and 2-oxoglutarate (2OG)-dependent oxygenase superfamily. This enzyme is reported to simultaneously catalyze the conversion of 2OG into ethylene and three CO2 molecules and the Cδ hydroxylation of l-arginine (l-Arg) while oxidatively decarboxylating 2OG to form succinate and carbon dioxide. A new plasmid construct for expression in recombinant Escherichia coli cells allowed for the purification of large amounts of EFE with activity greater than that previously recorded. A variety of assays were used to quantify and confirm the identity of the proposed products, including the first experimental demonstration of l-Δ(1)-pyrroline-5-carboxylate and guanidine derived from 5-hydroxyarginine. Selected l-Arg derivatives could induce ethylene formation without undergoing hydroxylation, demonstrating that ethylene production and l-Arg hydroxylation activities are not linked. Similarly, EFE utilizes the alternative α-keto acid 2-oxoadipate as a cosubstrate (forming glutaric acid) during the hydroxylation of l-Arg, with this reaction unlinked from ethylene formation. Kinetic constants were determined for both ethylene formation and l-Arg hydroxylation reactions. Anaerobic UV-visible difference spectra were used to monitor the binding of Fe(II) and substrates to the enzyme. On the basis of our results and what is generally known about EFE and Fe(II)- and 2OG-dependent oxygenases, an updated model for the reaction mechanism is presented.

  4. Synthesis and Characterization of Binuclear Schiff Base Complexes of Nickel, Copper, and Manganese.

    Science.gov (United States)

    1983-11-04

    D-Ri35 493 SYNTHESIS AND CHRACTERILATION OF BINUCLEAR SCHIFF BASE i/i COMPLEXES OF NICK-.U) ROCHESTER UNIV NV DEPT OF CHEMISTRY B C WHITMIORE ET AL...RESEARCH Contract NOO014-83-K-0154 fl Task No. NR 634-742 TECHNICAL REPORT NO. 1 ,Z Synthesis and Characterization of Binuclear Schiff Base Complexes

  5. Isocyanide and Phosphine Oxide Coordination in Binuclear Chromium Pacman Complexes.

    Science.gov (United States)

    Stevens, Charlotte J; Nichol, Gary S; Arnold, Polly L; Love, Jason B

    2013-12-01

    The new binuclear chromium Pacman complex [Cr2(L)] of the Schiff base pyrrole macrocycle H4L has been synthesized and structurally characterized. Addition of isocyanide, C≡NR (R = xylyl, (t)Bu), or triphenylphosphine oxide donors to [Cr2(L)] gives contrasting chemistry with the formation of the new coordination compounds [Cr2(μ-CNR)(L)], in which the isocyanides bridge the two Cr(II) centers, and [Cr2(OPPh3)2(L)], a Cr(II) phosphine oxide adduct with the ligands exogenous to the cleft.

  6. Measuring the Orientation of Taurine in the Active Site of the Non-Heme Fe (II)/α-Ketoglutarate Dependent Taurine Hydroxylase (TauD) using Electron Spin Echo Envelope Modulation (ESEEM) Spectroscopy

    OpenAIRE

    Casey, Thomas M.; Grzyska, Piotr K.; Hausinger, Robert P.; McCracken, John

    2013-01-01

    The position and orientation of taurine near the non-heme Fe(II) center of the α-ketoglutarate (α-KG) dependent taurine hydroxylase (TauD) was measured using Electron Spin Echo Envelope Modulation (ESEEM) spectroscopy. TauD solutions containing Fe(II), α-KG, and natural abundance taurine or specifically deuterated taurine were prepared anaerobically and treated with nitric oxide (NO) to make an S=3/2 {FeNO}7 complex that is suitable for robust analysis with EPR spectroscopy. Using ratios of E...

  7. Iron Supplementation Reverses the Reduction of Hydroxymethylcytosine in Hepatic DNA Associated With Chronic Alcohol Consumption in Rats

    Science.gov (United States)

    Tammen, Stephanie A.; Park, Jung Eun; Shin, Phil Kyung; Friso, Simonetta; Chung, Jayong; Choi, Sang-Woon

    2016-01-01

    Background Alcohol is known to affect two epigenetic phenomena, DNA methylation and DNA hydroxymethylation, and iron is a cofactor of ten-eleven translocation (TET) enzymes that catalyze the conversion from methylcytosine to hydroxymethylcytosine. In the present study we aimed to determine the effects of alcohol on DNA hydroxymethylation and further effects of iron on alcohol associated epigenetic changes. Methods Twenty-four male Sprague-Dawley rats were fed either Lieber-DeCarli alcohol diet (36% calories from ethanol) or Lieber-DeCarli control diet along with or without iron supplementation (0.6% carbonyl iron) for 8 weeks. Hepatic non-heme iron concentrations were measured by colorimetric assays. Protein levels of hepatic ferritin and transferrin receptor were determined by Western blotting. Methylcytosine, hydroxymethylcytosine and unmodified cytosine in DNA were simultaneously measured by liquid chromatography/mass spectrometry method. Results Iron supplementation significantly increased hepatic non-heme iron contents (P iron significantly increased hepatic ferritin levels and decreased hepatic transferrin receptor levels (P iron supplementation to alcohol diet did not change DNA hydroxymethylation. There was no significant difference in methylcytosine levels, while unmodified cytosine levels were significantly increased in alcohol-fed groups compared to control (95.61% ± 0.08% vs. 95.26% ± 0.12%, P = 0.03), suggesting that alcohol further increases the conversion from hydroxymethylcytosine to unmodified cytosine. Conclusions Chronic alcohol consumption alters global DNA hydroxymethylation in the liver but iron supplementation reverses the epigenetic effect of alcohol. PMID:28053961

  8. High-valent iron in chemical and biological oxidations.

    Science.gov (United States)

    Groves, John T

    2006-04-01

    Various aspects of the reactivity of iron(IV) in chemical and biological systems are reviewed. Accumulated evidence shows that the ferryl species [Fe(IV)O](2+) can be formed under a variety of conditions including those related to the ferrous ion-hydrogen peroxide system known as Fenton's reagent. Early evidence that such a species could hydroxylate typical aliphatic C-H bonds included regioselectivities and stereospecificities for cyclohexanol hydroxylation that could not be accounted for by a freely diffusing hydroxyl radical. Iron(IV) porphyrin complexes are also found in the catalytic cycles of cytochrome P450 and chloroperoxidase. Model oxo-iron(IV) porphyrin complexes have shown reactivity similar to the proposed enzymatic intermediates. Mechanistic studies using mechanistically diagnostic substrates have implicated a radical rebound scenario for aliphatic hydroxylation by cytochrome P450. Likewise, several non-heme diiron hydroxylases, AlkB (Omega-hydroxylase), sMMO (soluble methane monooxygenase), XylM (xylene monooxygenase) and T4moH (toluene monooxygenase) all show clear indications of radical rearranged products indicating that the oxygen rebound pathway is a ubiquitous mechanism for hydrocarbon oxygenation by both heme and non-heme iron enzymes.

  9. Anionic access to silylated and germylated binuclear heterocycles.

    Science.gov (United States)

    Boddaert, Thomas; François, Cyril; Mistico, Laetitia; Querolle, Olivier; Meerpoel, Lieven; Angibaud, Patrick; Durandetti, Muriel; Maddaluno, Jacques

    2014-08-04

    A simple access to silylated and germylated binuclear heterocycles, based on an original anionic rearrangement, is described. A set of electron-rich and electron-poor silylated aromatic and heteroaromatic substrates were tested to understand the mechanism and the factors controlling this rearrangement, in particular its regioselectivity. This parameter was shown to follow the rules proposed before from a few examples. Then, the effect of the substituents borne by the silicon itself, in particular the selectivity of the ligand transfer, was studied. Additionally, this chemistry was extended to germylated substrates. A hypervalent germanium species, comparable to the putative intermediate proposed with silicon, seems to be involved. However, a pathway implicating the elimination of LiCH2Cl was observed for the first time with this element, leading to unexpected products of the benzo-oxa (or benzo-aza) germol-type.

  10. Iron Absorption from Two Milk Formulas Fortified with Iron Sulfate Stabilized with Maltodextrin and Citric Acid

    Science.gov (United States)

    Pizarro, Fernando; Olivares, Manuel; Maciero, Eugenia; Krasnoff, Gustavo; Cócaro, Nicolas; Gaitan, Diego

    2015-01-01

    Background: Fortification of milk formulas with iron is a strategy widely used, but the absorption of non-heme iron is low. The purpose of this study was to measure the bioavailability of two iron fortified milk formulas designed to cover toddlers’ nutritional needs. These milks were fortified with iron sulfate stabilized with maltodextrin and citric acid. Methods: 15 women (33–47 years old) participated in study. They received on different days, after an overnight fast, 200 mL of Formula A; 200 mL of Formula B; 30 mL of a solution of iron and ascorbic acid as reference dose and 200 mL of full fat cow’s milk fortified with iron as ferrous sulfate. Milk formulas and reference dose were labeled with radioisotopes 59Fe or 55Fe, and the absorption of iron measured by erythrocyte incorporation of radioactive Fe. Results: The geometric mean iron absorption corrected to 40% of the reference dose was 20.6% for Formula A and 20.7% for Formula B, versus 7.5% of iron fortified cow’s milk (p < 0.001). The post hoc Sheffé indeed differences between the milk formulas and the cow’s milk (p < 0.001). Conclusion: Formulas A and B contain highly bioavailable iron, which contributes to covering toddlers’ requirements of this micronutrient. PMID:26529007

  11. Iron Absorption from Two Milk Formulas Fortified with Iron Sulfate Stabilized with Maltodextrin and Citric Acid

    Directory of Open Access Journals (Sweden)

    Fernando Pizarro

    2015-10-01

    Full Text Available Background: Fortification of milk formulas with iron is a strategy widely used, but the absorption of non-heme iron is low. The purpose of this study was to measure the bioavailability of two iron fortified milk formulas designed to cover toddlers´ nutritional needs. These milks were fortified with iron sulfate stabilized with maltodextrin and citric acid. Methods: 15 women (33–47 years old participated in study. They received on different days, after an overnight fast, 200 mL of Formula A; 200 mL of Formula B; 30 mL of a solution of iron and ascorbic acid as reference dose and 200 mL of full fat cow’s milk fortified with iron as ferrous sulfate. Milk formulas and reference dose were labeled with radioisotopes 59Fe or 55Fe, and the absorption of iron measured by erythrocyte incorporation of radioactive Fe. Results: The geometric mean iron absorption corrected to 40% of the reference dose was 20.6% for Formula A and 20.7% for Formula B, versus 7.5% of iron fortified cow’s milk (p < 0.001. The post hoc Sheffé indeed differences between the milk formulas and the cow’s milk (p < 0.001. Conclusion: Formulas A and B contain highly bioavailable iron, which contributes to covering toddlers´ requirements of this micronutrient.

  12. Iron metabolism in hepcidin1 knockout mice in response to phenylhydrazine-induced hemolysis.

    Science.gov (United States)

    Masaratana, Patarabutr; Latunde-Dada, Gladys O; Patel, Neeta; Simpson, Robert J; Vaulont, Sophie; McKie, Andrew T

    2012-08-15

    Hepcidin, an iron regulatory peptide, plays a central role in the maintenance of systemic iron homeostasis by inducing the internalization and degradation of the iron exporter, ferroportin. Hepcidin expression in the liver is regulated in response to several stimuli including iron status, erythropoietic activity, hypoxia and inflammation. Hepcidin expression has been shown to be reduced in phenylhydrazine-treated mice, a mouse model of acute hemolysis. In this mouse model, hepcidin suppression was associated with increased expression of molecules involved in iron transport and recycling. The present study aims to explore whether the response to phenylhydrazine treatment is affected by hepcidin deficiency and/or the subsequently altered iron metabolism. Hepcidin1 knockout (Hamp(-/-)) and wild type mice were treated with phenylhydrazine or saline and parameters of iron homeostasis were determined 3 days after the treatment. In wild type mice, phenylhydrazine administration resulted in significantly reduced serum iron, increased tissue non-heme iron levels and suppressed hepcidin expression. The treatment was also associated with increases in membrane ferroportin protein levels and spleen heme oxygenase 1 mRNA expression. In addition, trends toward increased mRNA expression of duodenal iron transporters were also observed. In contrast, serum iron and tissue non-heme iron levels in Hamp(-/-) mice were unaffected by the treatment. Moreover, the effects of phenylhydrazine on the expression of ferroportin and duodenal iron transporters were not observed in Hamp(-/-) mice. Interestingly, mRNA levels of molecules involved in splenic heme uptake and degradation were significantly induced by Hamp disruption. In summary, our study demonstrates that the response to phenylhydrazine-induced hemolysis differs between wild type and Hamp(-/-) mice. This observation may be caused by the absence of hepcidin per se or the altered iron homeostasis induced by the lack of hepcidin in

  13. Applications of density functional theory to iron-containing molecules of bioinorganic interest.

    Science.gov (United States)

    Hirao, Hajime; Thellamurege, Nandun; Zhang, Xi

    2014-01-01

    The past decades have seen an explosive growth in the application of density functional theory (DFT) methods to molecular systems that are of interest in a variety of scientific fields. Owing to its balanced accuracy and efficiency, DFT plays particularly useful roles in the theoretical investigation of large molecules. Even for biological molecules such as proteins, DFT finds application in the form of, e.g., hybrid quantum mechanics and molecular mechanics (QM/MM), in which DFT may be used as a QM method to describe a higher prioritized region in the system, while a MM force field may be used to describe remaining atoms. Iron-containing molecules are particularly important targets of DFT calculations. From the viewpoint of chemistry, this is mainly because iron is abundant on earth, iron plays powerful (and often enigmatic) roles in enzyme catalysis, and iron thus has the great potential for biomimetic catalysis of chemically difficult transformations. In this paper, we present a brief overview of several recent applications of DFT to iron-containing non-heme synthetic complexes, heme-type cytochrome P450 enzymes, and non-heme iron enzymes, all of which are of particular interest in the field of bioinorganic chemistry. Emphasis will be placed on our own work.

  14. Accumulation of iron in the putamen predicts its shrinkage in healthy older adults: A multi-occasion longitudinal study.

    Science.gov (United States)

    Daugherty, Ana M; Raz, Naftali

    2016-03-01

    Accumulation of non-heme iron is believed to play a major role in neurodegeneration of the basal ganglia. In healthy aging, however, the temporal relationship between change in brain iron content and age-related volume loss is unclear. Here, we present the first long-term longitudinal multi-occasion investigation of changes in iron content and volume in the neostriatum in a sample of healthy middle-aged and older adults (N=32; ages 49-83years at baseline). Iron content, estimated via R2* relaxometry, increased in the putamen, but not the caudate nucleus. In the former, the rate of accumulation was coupled with change in volume. Moreover, greater baseline iron content predicted faster shrinkage and smaller volumes seven years later. Older age partially accounted for individual differences in neostriatal iron content and volume, but vascular risk did not. Thus, brain iron content may be a promising biomarker of impending decline in normal aging.

  15. Syntheses of Binuclear Copper(Ⅰ)Complexes Containing Benzimidazole

    Institute of Scientific and Technical Information of China (English)

    LIU Ying-Fan; ZHAO Dong; GUO Li-Bing; ZHENG Xin; SUN Yu-An

    2005-01-01

    A binuclear copper(Ⅰ) complex [Cu2(dppm)2(C7H6N2)2](NO3)2 (C7H6N2 = benzimidazole, dppm = Ph2PCH2PPh2) has been synthesized and characterized by X-ray crystallography.The crystal belongs to monoclinic, space group C2/c with a = 14.167(3), b = 21.209(4), c =20.680(4) A, β = 103.93(3)°, C32H28CuN3O3P2, Mr = 628.05, Z = 8,μ = 0.868 mm-1, V = 6031 (2)(。A)3,F(000) = 2592, Dc= 1.383 g/cm3, R = 0.0593 and wR = 0.1736.A total of 5297 independent reflec tions were collected, of which 3503 were observed with I > 2σ(I).The central copper atom is tri-coordinated by phosphorus atoms from bridging dppm and nitrogen atom from benzimidazole.In the coordination sphere, the bond lengths of Cu-P(1) and Cu-P(2) are 2.2607(17) and 2.2503(16)(。A),respectively and the P-Cu-P bond angle is 127.26(6)°.

  16. Effects of vitamin E on hematological iron status and non-heme iron content in rat%维生素E对大鼠血液铁状态和脑铁代谢的影响

    Institute of Scientific and Technical Information of China (English)

    肖德生; 刘淑杰; 蒋璐; 车力龙; 钱海; 曹惠芝

    2006-01-01

    目的:观察不同含量维生素E(VE)膳食对大鼠血液铁状态和脑铁贮存的影响.方法:雌性SD大鼠随机分为3组:VE缺乏组(LVE),正常含量VE组(NVE),补充VE组(HVE).喂养3个月后断头取血和脑组织,测定血液铁状态指标和各脑区非血红素铁(NHI)含量.结果:与NVE组相比,LVE组血红蛋白(Hb)浓度显著升高,总铁结合力(TIBC)显著增大,血浆铁浓度(PI)没有显著变化;HVE组Hb没有显著变化,但TIBC降低,PI升高,导致血浆铁饱和度升高.与NVE组相比,LVE组和HVE组下丘脑的NHI均显著降低,延髓NHI均显著升高,HVE组中脑的NHI显著升高,但LVE组没有显著变化,在两组其他脑区NHI含量均未发现显著变化.结论:膳食VE含量变化可改变血液铁状态和脑内铁稳态.

  17. Bimetallic Oxidation Catalysts. Oxygen Insertion into an Aryl–Hydrogen Bond of a Binuclear Copper(I) Complex

    NARCIS (Netherlands)

    Gelling, O.J.; Bolhuis, F. van; Meetsma, A.; Feringa, Bernard

    1988-01-01

    The binuclear copper(I) complex of 1,3-bis[N-(2-pyridylethyl)formimidoyl]benzene reacts with molecular oxygen to give a phenoxy- and hydroxy-bridged binuclear copper(II) complex; the structures of both complexes have been determined by X-ray crystallography.

  18. Mitochondrial iron metabolism and sideroblastic anemia.

    Science.gov (United States)

    Sheftel, Alex D; Richardson, Des R; Prchal, Josef; Ponka, Prem

    2009-01-01

    Sideroblastic anemias are a heterogeneous group of disorders, characterized by mitochondrial iron overload in developing red blood cells. The unifying characteristic of all sideroblastic anemias is the ring sideroblast, which is a pathological erythroid precursor containing excessive deposits of non-heme iron in mitochondria with perinuclear distribution creating a ring appearance. Sideroblastic anemias may be hereditary or acquired. Hereditary sideroblastic anemias are caused by defects in genes present on the X chromosome (mutations in the ALAS2, ABCB7, or GRLX5 gene), genes on autosomal chromosomes, or mitochondrial genes. Acquired sideroblastic anemias are either primary (refractory anemia with ring sideroblasts, RARS, representing one subtype of the myelodysplastic syndrome) or secondary due to some drugs, toxins, copper deficiency, or chronic neoplastic disease. The pathogenesis of mitochondrial iron loading in developing erythroblasts is diverse. Ring sideroblasts can develop as a result of a heme synthesis defect in erythroblasts (ALAS2 mutations), a defect in iron-sulfur cluster assembly, iron-sulfur protein precursor release from mitochondria (ABCB7 mutations), or by a defect in intracellular iron metabolism in erythroid cells (e.g. RARS).

  19. Dietary iron intake, body iron stores, and the risk of type 2 diabetes: a systematic review and meta-analysis

    Directory of Open Access Journals (Sweden)

    Bao Wei

    2012-10-01

    Full Text Available Abstract Background Excess iron has been shown to induce diabetes in animal models. However, the results from human epidemiologic studies linking body iron stores and iron intake to the risk of type 2 diabetes mellitus (T2DM are conflicting. In this study, we aimed to systematically evaluate the available evidence for associations between iron intake, body iron stores, and the risk of T2DM. Methods A systematic search of the PubMed/MEDLINE and EMBASE databases to the end of 22 April 2012 was performed, and reference lists of retrieved articles were screened. Two reviewers independently evaluated the eligibility of inclusion and extracted the data. Pooled relative risks (RRs and 95% confidence intervals (CIs were calculated using random-effects models. Results We reviewed 449 potentially relevant articles, and 11 prospective studies were included in the analysis. A meta-analysis of five studies gave a pooled RR for T2DM of 1.33 (95% CI 1.19 to 1.48; P0.001 in individuals with the highest level of heme iron intake, compared with those with the lowest level. The pooled RR for T2DM for a daily increment of 1 mg of heme iron intake was 1.16 (1.09 to 1.23, P0.001. Body iron stores, as measured by ferritin, soluble transferrin receptor (sTfR and the sTfR:ferritin ratio, were significantly associated with the risk of T2DM. The pooled RRs for T2DM in individuals with the highest versus the lowest intake of ferritin levels was 1.70 (1.27-2.27, P0.001 before adjustment for inflammatory markers and 1.63 (1.03-2.56, P = 0.036 after adjustment. We did not find any significant association of dietary intakes of total iron, non-heme, or supplemental iron intake with T2DM risk. Conclusion Higher heme iron intake and increased body iron stores were significantly associated with a greater risk of T2DM. Dietary total iron, non-heme iron, or supplemental iron intakes were not significantly associated with T2DM risk.

  20. Effect of dietary iron loading on recognition memory in growing rats.

    Science.gov (United States)

    Han, Murui; Kim, Jonghan

    2015-01-01

    While nutritional and neurobehavioral problems are associated with both iron deficiency during growth and overload in the elderly, the effect of iron loading in growing ages on neurobehavioral performance has not been fully explored. To characterize the role of dietary iron loading in memory function in the young, weanling rats were fed iron-loading diet (10,000 mg iron/kg diet) or iron-adequate control diet (50 mg/kg) for one month, during which a battery of behavioral tests were conducted. Iron-loaded rats displayed elevated non-heme iron levels in serum and liver, indicating a condition of systemic iron overload. In the brain, non-heme iron was elevated in the prefrontal cortex of iron-loaded rats compared with controls, whereas there was no difference in iron content in other brain regions between the two diet groups. While iron loading did not alter motor coordination or anxiety-like behavior, iron-loaded rats exhibited a better recognition memory, as represented by an increased novel object recognition index (22% increase from the reference value) than control rats (12% increase; P=0.047). Western blot analysis showed an up-regulation of dopamine receptor 1 in the prefrontal cortex from iron-loaded rats (142% increase; P=0.002). Furthermore, levels of glutamate receptors (both NMDA and AMPA) and nicotinic acetylcholine receptor (nAChR) were significantly elevated in the prefrontal cortex of iron-loaded rats (62% increase in NR1; 70% increase in Glu1A; 115% increase in nAChR). Dietary iron loading also increased the expression of NMDA receptors and nAChR in the hippocampus. These results support the idea that iron is essential for learning and memory and further reveal that iron supplementation during developmental and rapidly growing periods of life improves memory performance. Our investigation also demonstrates that both cholinergic and glutamatergic neurotransmission pathways are regulated by dietary iron and provides a molecular basis for the role of iron

  1. Effect of dietary iron loading on recognition memory in growing rats.

    Directory of Open Access Journals (Sweden)

    Murui Han

    Full Text Available While nutritional and neurobehavioral problems are associated with both iron deficiency during growth and overload in the elderly, the effect of iron loading in growing ages on neurobehavioral performance has not been fully explored. To characterize the role of dietary iron loading in memory function in the young, weanling rats were fed iron-loading diet (10,000 mg iron/kg diet or iron-adequate control diet (50 mg/kg for one month, during which a battery of behavioral tests were conducted. Iron-loaded rats displayed elevated non-heme iron levels in serum and liver, indicating a condition of systemic iron overload. In the brain, non-heme iron was elevated in the prefrontal cortex of iron-loaded rats compared with controls, whereas there was no difference in iron content in other brain regions between the two diet groups. While iron loading did not alter motor coordination or anxiety-like behavior, iron-loaded rats exhibited a better recognition memory, as represented by an increased novel object recognition index (22% increase from the reference value than control rats (12% increase; P=0.047. Western blot analysis showed an up-regulation of dopamine receptor 1 in the prefrontal cortex from iron-loaded rats (142% increase; P=0.002. Furthermore, levels of glutamate receptors (both NMDA and AMPA and nicotinic acetylcholine receptor (nAChR were significantly elevated in the prefrontal cortex of iron-loaded rats (62% increase in NR1; 70% increase in Glu1A; 115% increase in nAChR. Dietary iron loading also increased the expression of NMDA receptors and nAChR in the hippocampus. These results support the idea that iron is essential for learning and memory and further reveal that iron supplementation during developmental and rapidly growing periods of life improves memory performance. Our investigation also demonstrates that both cholinergic and glutamatergic neurotransmission pathways are regulated by dietary iron and provides a molecular basis for the

  2. High protein and iron-folate crackers supplementation on the iron status of pregnant women

    Directory of Open Access Journals (Sweden)

    Faisal Anwar

    2003-12-01

    Full Text Available Previous studies have revealed that several factors influenced the relatively low success of iron supplementation for pregnant women. The factors included poor distribution, low coverage and compliance, as well as low absorption. The aim of this study is to measure the iron status of pregnant women after consuming crackers containing fish powder and iron-folate. This study was carried out in the Purworejo district (Central Java from February through October 2002. Using a randomized controlled trial (RCT design, 70 pregnant women in their second-third month of pregnancy were recruited, and divided into two groups. Ten women dropped out during the study. The first group consisted of 28 women were given protein – iron enriched crackers (PIEC group, while the second group of 32 women were given iron–enriched crackers (IEC group for a total of 12 weeks. The results showed that the hemoglobin (Hb levels and serum transferrin receptors (sTfR of both groups were increased. Serum ferritins (SF of both groups were decreased. At the end of the study, the increase in Hb and sTfR levels between the two groups were significantly different, while the decrease in SF was not significantly different. Animal protein from fish powder tended to improve absorption of non-heme iron among pregnant women, resulting in improved Hb and sTfR levels. (Med J Indones 2003; 12: 243-6Keywords: pregnant women, anemia, iron deficiency, high protein crackers

  3. A fluorescent bis(benzoxazole) ligand: toward binuclear Zn(II)-Zn(II) assembly.

    Science.gov (United States)

    Chu, Qinghui; Medvetz, Doug A; Panzner, Matthew J; Pang, Yi

    2010-06-14

    A bis(benzoxazole) ligand (HL) has been synthesized, and its reaction with Zn(OAc)(2) has led to fluorescent complexes via formation of binuclear Zn(II)-Zn(II) cores. The ligand-to-metal ratio of the complexes varies from 1 : 1 to 2 : 1, depending on the reaction conditions. A large binding constant K = 8.3 x 10(20) [M(-3)] has been determined for the reaction L + Zn(2+)-->L(2):Zn(2)(2+). The result indicates that the bis(benzoxazole) ligand is a useful building block to construct a binuclear core. On the basis of X-ray analysis, the binuclear Zn(II)-Zn(II) distance in the complexes is determined to be approximately 3.22 A, which is quite comparable to that found in the enzymes (3.3 A). Absorption and fluorescence study shows that a subtle chemical environmental change within the binuclear core can induce a large optical response.

  4. Brain iron homeostasis.

    Science.gov (United States)

    Moos, Torben

    2002-11-01

    deficiency altered the cellular content of these proteins so that transferrin receptors were higher and ferritin lower. The transport of iron from brain to blood was addressed in the last part of the thesis. It was found that in the case of iron and transferrin, there is no evidence showing other significant routes of transport from the brain extracellular fluid into the blood than drainage to the ventricular system followed by export to the blood via the arachnoid villi. The turnover of transferrin in the CSF was found to be very high. For reasons mentioned above, transferrin of the CSF is of little significance for transport and cellular delivery of iron to transferrin receptor-expressing neurons. Instead, transferrin of the CSF probably plays a significant role for neutralization and export to the blood of metals, including iron. Once appearing in blood, transferrin of the CSF was degraded at the same rate as intravenously injected transferrin, which indicates that the transferrin of CSF is not altered to an extent that changes its catabolism during the passage from CSF to blood plasma. The metabolism of iron in the developing brain was found to differ markedly when compared to that of the adult brain. A developing regulated transfer of iron to the brain was reflected morphologically by a higher content of transferrin receptors and non-heme iron in endothelial cells of the developing rat brain than in the adult. Neurons had a very low level of transferrin receptors. After about 20 days of age, iron transport into the brain decreased rapidly, and transferrin receptors appeared on neurons. Iron and transferrin injected into the ventricular system of the developing brain were much more widely distributed in the brain parenchyma than in the adult brain. This high accumulation of substances injected into the ventricles in young animals is probably due to the lower rate of production and turnover of CSF, which will increase the time available for diffusion of proteins into the

  5. GASTROINTESTINAL TRACT AND IRON ABSORPTION: A REVIEW

    Directory of Open Access Journals (Sweden)

    Gladys O. LATUNDE-DADA

    2009-07-01

    Full Text Available

    Iron is an important element in many metabolic processes. The bioavailability of iron is a function of solubilization and reduction of Fe3+ in the stomach, hydrolysis, neutralization, ligand complexes and transport through the mucus layer of the intestine. The bioavailibility of non-heme Fe is determined by enhancers of iron absorption such as meat, amino acids, organic acids, antagonized by the inhibitors as bran, phytate and fibre. Haem Fe is absorbed directly as an intact metalloprotein porphyrin complex. The pathways of inorganic Fe into the mucosa cell Include endocytosis, electrogenic fatty acid mediated transcellular pathway, nonspecific paracellular permeation ar probably facilitated transcellular diffusion. The redox model proposes the reduction of Fe3+ by a transplasma membrane ferric reductase in lhe duodenal mucosa and the translocation of the Fe2+ across the cell probably by the nonesterified fatty acid. The mucin-mobilferrin-integrin pathway on the other hand involves the delivery of Fe-mucin complex in the lumen to the integrins of mucosa surface for translocation lo mobllferrin in the cytosol. The transfer of absorbed Fe iron from the mucosa into the blood is dependent on a number of regulatory intracellular and systemic factors

  6. Ab Initio Computation of Spin Orbit Coupling Effects on Magnetic Properties of Iron-Containing Complexes and Proteins

    Science.gov (United States)

    Aquino, Fredy; Rodriguez, Jorge H.

    2007-03-01

    Zero-Field Splittings (ZFS) in metalloproteins and other metal complexes arise from the combined action of crystalline fields acting on the metal valence electrons and spin-orbit coupling (SOC), a relativistic effect. The ab-initio calculation of ZFS parameters of metal-containing (bio)molecules is a challenging computational problem of practical relevance to metalloenzyme biochemistry, inorganic chemistry, and molecular-based bio- nanotechnology. We have implemented a methodology which treats the nonrelativistic electronic structure of magnetic (bio) molecules within the framework of spin density functional theory (SDFT) and adds the relativistic effects of SOC via perturbation theory (PT). This combined SDFT-PT approach allowed us to compute the ZFS parameters of iron-containing complexes and non-heme iron proteins with a good degree of accuracy. We also developed a semiquantitative approach to elucidate the physico-chemical origin of the magnitudes of ZFS parameters. We present results for biochemically relevant iron complexes and for nitric oxide-containing non-heme iron proteins, such as isopenicillin N synthase, which have unusually large ZFS. The computed ZFS parameters are in good agreement with experiment. Supported by NSF CAREER Award CHE- 0349189 (JHR).

  7. Measuring the orientation of taurine in the active site of the non-heme Fe(II)/α-ketoglutarate-dependent taurine hydroxylase (TauD) using electron spin echo envelope modulation (ESEEM) spectroscopy.

    Science.gov (United States)

    Casey, Thomas M; Grzyska, Piotr K; Hausinger, Robert P; McCracken, John

    2013-09-12

    The position and orientation of taurine near the non-heme Fe(II) center of the α-ketoglutarate (α-KG)-dependent taurine hydroxylase (TauD) was measured using Electron Spin Echo Envelope Modulation (ESEEM) spectroscopy. TauD solutions containing Fe(II), α-KG, and natural abundance taurine or specifically deuterated taurine were prepared anaerobically and treated with nitric oxide (NO) to make an S = 3/2 {FeNO}(7) complex that is suitable for robust analysis with EPR spectroscopy. Using ratios of ESEEM spectra collected for TauD samples having natural abundance taurine or deuterated taurine, (1)H and (14)N modulations were filtered out of the spectra and interactions with specific deuterons on taurine could be studied separately. The Hamiltonian parameters used to calculate the amplitudes and line shapes of frequency spectra containing isolated deuterium ESEEM were obtained with global optimization algorithms. Additional statistical analysis was performed to validate the interpretation of the optimized parameters. The strongest (2)H hyperfine coupling was to a deuteron on the C1 position of taurine and was characterized by an effective dipolar distance of 3.90 ± 0.25 Å from the {FeNO}(7) paramagnetic center. The principal axes of this C1-(2)H hyperfine coupling and nuclear quadrupole interaction tensors were found to make angles of 26 ± 5 and 52 ± 17°, respectively, with the principal axis of the {FeNO}(7) zero-field splitting tensor. These results are discussed within the context of the orientation of substrate taurine prior to the initiation of hydrogen abstraction.

  8. Conserved balance of hepatocyte nuclear DNA content in mononuclear and binuclear hepatocyte populations during the course of chronic viral hepatitis

    Institute of Scientific and Technical Information of China (English)

    Hidenori Toyoda; Takashi Kumada; Olivier Bregerie; Christian Brechot; Chantal Desdouets

    2006-01-01

    AIM: To analyze the percentages of hepatocytes with increased nuclear DNA content, i.e., tetraploid (4n) and octoploid (8n) nuclei, and then compared mononuclear and binuclear hepatocyte populations:METHODS: The percentages of mononuclear diploid(2n), 4n, and 8n hepatocytes and those of binuclear 2× 2n, 2 × 4n, and 2 × 8n hepatocytes were determined with a method that can simultaneously measure hepatocyte nuclear DNA content and binuclearity in 62patients with chronic hepatitis B or C. The percentage of 4n and 8n hepatocytes in the mononuclear hepatocyte population was compared with the percentage of 2 ×4n and 2 × 8n hepatocytes in the binuclear hepatocyte population.RESULTS: The percentages of 4n and 8n hepatocytes in mononuclear hepatocytes and 2 × 4n and 2 × 8n hepatocytes in binuclear hepatocytes were similar,regardless of the activity or fibrosis grade of chronic hepatitis and regardless of the infecting virus.CONCLUSION: The distribution of nuclear DNA content within mononuclear and binuclear hepatocyte populations was conserved during the course of chronic viral hepatitis.

  9. A switch in the electron transfer from heme a to binuclear centre of cytochrome c oxidase

    Institute of Scientific and Technical Information of China (English)

    王敖金; 徐建兴

    2002-01-01

    New experimental evidence that a switch controls the reduction of the heme a3-CuB binuclear centre has beenobserved in the N2-dried thin film of purified cytochrome oxidase. When immersing the enzyme film into the acidphosphate buffer with extremely low concentration of dithionite, a spectrum was given to show a reduction of heme awith no electrons resting on CuA. By increasing dithionite, electrons could be accumulated gradually on CuA, but thebinuclear centre still remains in the oxidized state. When the accumulation of electrons on CuA and/or heme a exceededa threshold, a turnover of reduction of the binuclear centre and oxidation of heme a occurred abruptly. This switch-likeaction is pH-dependent.

  10. Thioetherification of chloroheteroarenes: a binuclear catalyst promotes wide scope and high functional-group tolerance.

    Science.gov (United States)

    Platon, Mélanie; Wijaya, Novi; Rampazzi, Vincent; Cui, Luchao; Rousselin, Yoann; Saeys, Mark; Hierso, Jean-Cyrille

    2014-09-22

    A constrained binuclear palladium catalyst system affords selective thioetherification of a wide range of functionalized arenethiols with chloroheteroaromatic partners with the highest turnover numbers (TONs) reported to date and tolerates a large variety of reactive functions. The scope of this system includes the coupling of thiophenols with six- and five-membered 2-chloroheteroarenes (i.e., functionalized pyridine, pyrazine, quinoline, pyrimidine, furane, and thiazole) and 3-bromoheteroarenes (i.e., pyridine and furane). Electron-rich congested thiophenols and fluorinated thiophenols are also suitable partners. The coupling of unprotected amino-2-chloropyridines with thiophenol and the successful employment of synthetically valuable chlorothiophenols are described with the same catalyst system. DFT studies attribute the high performance of this binuclear palladium catalyst to the decreased stability of thiolate-containing resting states. Palladium loading was as low as 0.2 mol %, which is important for industrial application and is a step forward in solving catalyst activation/deactivation problems.

  11. Binuclear magnesium amidoborane complexes : characterization of a trinuclear thermal decomposition product

    NARCIS (Netherlands)

    Spielmann, Jan; Harder, Sjoerd

    2011-01-01

    The bis-beta-diketimine with a meta-phenylene bridge (META-H-2: DIPPN(H)CMeCHCMeN-C6H4-NCMeCHCMeN(H)DIPP; DIPP = 2,6-iPr-C6H3) reacted with two equivalents of nBu(2)Mg to give the bis-beta-diketiminate complex META-(MgnBu)(2). The latter binuclear magnesium complex was converted to META-[MgNH(iPr)BH

  12. Magnetic, electronic and electrochemical studies of mono and binuclear Cu(II) complexes using novel macrocyclic ligands.

    Science.gov (United States)

    Gupta, Nidhi; Gupta, Rachna; Chandra, Sulekh; Bawa, S S

    2005-04-01

    A series of new mono and binuclear copper (II) complexes [Cul]X(2)and [Cu(2)lX(2)] where 1 = L(1), L(2) and L(3) are the macrocyclic ligands. In mononuclear complexes the geometry of Cu(II) ion is distorted squareplanar and in binuclear complexes the geometry of Cu(II) is tetragonal. The synthesized complexes were characterized by spectroscopic (IR,UV-vis and ESR) techniques. Electrochemical studies of the complexes reveals that all the mononuclear Cu(II) complexes show a single quasireversible one-electron transfer reduction wave (E(pc) = -0.76 to -0.84V) and the binuclear complexes show two quasireversible one electron transfer reduction waves (E(pc)(1) = -0.86 to -1.01V, E(pc)(2) = -1.11 to -1.43V) in cathodic region. The ESR spectra of mononuclear complexes show four lines with nuclear hyperfine splittings with the observed g(11) values in the ranges 2.20-2.28, g( perpendicular) = 2.01-2.06 and A(11) = 125-273. The binuclear complexes show a broad ESR spectra with g = 2.10-2.11. The room temperature magnetic moment values for the mononuclear complexes are in the range [mu(eff) = 1.70-1.72BM] and for the binuclear complexes the range is [mu(eff) = 1.46-1.59BM].

  13. Intermittent hypoxia stimulates formation of binuclear neurons in brain cortex- a role of cell fusion in neuroprotection?

    Science.gov (United States)

    Paltsyn, Alexander A; Manukhina, Eugenia B; Goryacheva, Anna V; Downey, H Fred; Dubrovin, Ivan P; Komissarova, Svetlana V; Kubatiev, Aslan A

    2014-05-01

    Oligodendrocyte fusion with neurons in the brain cortex is a part of normal ontogenesis and is a possible means of neuroregeneration. Following such fusion, the oligodendrocyte nucleus undergoes neuron-specific reprogramming, resulting in the formation of binuclear neurons, which doubles the functional capability of the neuron. In this study, we tested the hypothesis that the formation of binuclear neurons is involved in long-term adaptation of the brain to intermittent hypobaric hypoxia, which is known to be neuroprotective. Rats were adapted to hypoxia in an altitude chamber at a simulated altitude of 4000 m above sea level for 14 days (30 min increasing to 4 h, daily). One micrometer sections of the left motor cortex were analyzed by light microscopy. Phases of the fusion and reprogramming process were recorded, and the number of binuclear neurons was counted for all section areas containing pyramidal neurons of layers III-V. For the control group subjected to sham hypoxia, the density of binuclear neurons was 4.49 ± 0.32 mm(2). In the hypoxia-adapted group, this density increased to 5.71 ± 0.39 mm(2) (P neurons did not differ from the number observed in the control group. We suggest that the increased content of binuclear neurons may serve as a structural basis for the neuroprotective effects of the adaptation to hypoxia.

  14. Comparison between the availability of iron in the presence of vitamin a and β-carotene in foods and medications

    Directory of Open Access Journals (Sweden)

    Fabiana Cristina Camargo Martini

    2011-06-01

    Full Text Available The objective of this work was to verify the availability of iron in the presence of vitamin A as components of foods and in combinations with medicines. The iron available was measured in the presence of vitamin A in foods - common bean (B, beef liver (Li and carrot (C - and medicines - Fer-In-Sol® (Fer (Mead Johnson, Arovit® (A (Roche and Neutrofer® (N (Sigma Pharma - as well as in combinations of both. β-carotene, vitamin A, total iron, heme and non heme iron, percentage of dialyzable iron and amount of dialyzable iron was determined. Vitamin A and β-carotene had a positive effect on the percentage of iron dialysis. Carrot and liver had a better percentage of dialyzable iron than their respective medicine at similar concentrations. Therefore, we can conclude that there has been an influence of vitamin A over the dialysis of iron, being the mixtures containing liver the ones which achieved the highest concentrations of dialyzable iron, and also that, according to the amounts needed to obtain the daily recommended intake of iron, they are good for consumption.

  15. Hydrolysis of p-Nitrophenyl Picolinate Catalyzed by Mono-and Binuclear Transition Metal Complexes with Polyether Bridged Dihydroxamic Acid

    Institute of Scientific and Technical Information of China (English)

    李建章; 李鸿波; 冯发美; 谢家庆; 李慎新; 周波; 秦圣英

    2005-01-01

    Two polyether bridged dihydroxamic acids and their mono-and binuclear manganese(Ⅱ), zinc(Ⅱ) complexes have been synthesized and employed as models to mimic hydrolase in catalytic hydrolysis of p-nitrophenyl picolinate (PNPP). The reaction kinetics and the mechanism of hydrolysis of PNPP have been investigated. The kinetic mathematical model for PNPP cleaved by the complexes has been proposed. The effects of the different central metal ion, mono-and binuclear metal, the pseudo-macrocyclic polyether constructed by polyethoxy group of the complexes, and reactive temperature on the rate for catalytic hydrolysis of PNPP have been examined. The results showed that the transition metal dthydroxamates exhibited high catalytic activity to the hydrolysis of PNPP, the catalytic activity of binuclear complexes was higher than that of mononuclear ones, and the pseudo-macrocyclic polyether might synergetically activate H20 coordinated to metal ion with central metal ion together and promote the catalytic hydrolysis of PNPP.

  16. Chromium-chromium interaction in a binuclear mixed-valent Cr(I)-Cr(II) complex.

    Science.gov (United States)

    Alzamly, Ahmed; Gorelsky, Serge I; Gambarotta, Sandro; Korobkov, Ilia; Le Roy, Jennifer; Murugesu, Muralee

    2014-11-03

    A mixed-valent Cr(I)-Cr(II) binuclear complex, {κ(1),κ(2),κ(3)-N,P,P-cyclo[(Ph)PCH2N(CH2Ph)CH2]}2(CrCl2)[Cr(μ-Cl)(AlClMe2)]·4toluene (1), of a P2N2 cyclic ligand was obtained upon treatment of the chromium precursor with alkylaluminum. Complex 1 was accessible from either its trivalent or divalent precursors, and density functional theory calculations revealed the presence of only σ- and π-orbital interactions in the Cr-Cr bond.

  17. Consumption of cow's milk as a cause of iron deficiency in infants and toddlers.

    Science.gov (United States)

    Ziegler, Ekhard E

    2011-11-01

    Consumption of cow's milk (CM) by infants and toddlers has adverse effects on their iron stores, a finding that has been well documented in many localities. Several mechanisms have been identified that may contribute to iron deficiency in this young population group. The most important of these is probably the low iron content of CM, which makes it difficult for infants to obtain the amounts of iron needed for growth. A second mechanism is the occult intestinal blood loss associated with CM consumption during infancy, a condition that affects about 40% of otherwise healthy infants. Loss of iron in the form of blood diminishes with age and ceases after the age of 1 year. A third mechanism is the inhibition of non-heme iron absorption by calcium and casein, both of which are present in high amounts in CM. Fortification of CM with iron, as practiced in some countries, can protect infants and toddlers against CM's negative effects on iron status. Consumption of CM produces a high renal solute load, which leads to a higher urine solute concentration than consumption of breast milk or formula, thereby narrowing the margin of safety during dehydrating events, such as diarrhea. The high protein intake from CM may also place infants at increased risk of obesity in later childhood. It is thus recommended that unmodified, unfortified CM not be fed to infants and that it be fed to toddlers in modest amounts only.

  18. Iron Chelation

    Science.gov (United States)

    Skip to main content Menu Donate Treatments Therapies Iron Chelation Iron chelation therapy is the main treatment ... have iron overload and need treatment. What is iron overload? Iron chelation therapy is used when you ...

  19. Alterações provocadas pela irradiação e armazenamento nos teores de ferro heme em carne de frango Alteration by irradiation and storage at amount of heme iron in poultry meat

    Directory of Open Access Journals (Sweden)

    Adriana Régia Marques de Souza

    2007-06-01

    Full Text Available Estudos sobre o efeito da irradiação e do armazenamento em carnes de frango foram realizados para se conhecer melhor sua influência nos teores de ferro heme, não-heme, cor e pigmentos totais. Foram estudados coxa e filé de peito de frango. Estes foram irradiados a 0, 1 e 2 kGy e armazenados por 14 dias a 4 °C em câmara refrigerada. A determinação do conteúdo de heme e não-heme de carnes foi realizada através do método colorimétrico, empregando-se o reagente Ferrozine. Os valores de ferro heme foram influenciados tanto pela irradiação quanto pelo armazenamento, diminuindo seus teores com o passar do tempo. O ferro não-heme também foi influenciado tanto pelas doses empregadas quanto pelo tempo de estocagem, porém aumentou seus valores com o passar do tempo, devido à conversão do heme em não-heme. A cor não se mostrou influenciada pelas doses estudadas, somente pela estocagem, e os pigmentos totais foram afetados tanto pela irradiação quanto pelo tempo, diminuindo seus valores com o aumento do tempo de armazenamento. A irradiação se mostrou um bom método para conservação do ferro, visto que aumentou os teores de acordo com o aumento das doses.Studies of irradiation and storage effects in chicken were carried out to discover the influence in iron heme, non-heme amount, color and total pigments. Chicken thighs and chicken breast were studied. These were irradiated to 0, 1 and 2 kGy stored by 14 days to 4 °C in refrigerator. Determining the heme content and non-heme of meat was done using the colorimeter method and the Ferrozine reagent. The values of iron heme were influenced both by the irradiation and the storage, reducing the amount throughout the course of time. The iron non-heme was also influenced by the doses and the storage time, however the values increased throughout the course of time, because of the conversion of iron heme in non-heme. The color did not show that it was influenced by the studied doses

  20. Oxo-group-14-element bond formation in binuclear uranium(V) Pacman complexes.

    Science.gov (United States)

    Jones, Guy M; Arnold, Polly L; Love, Jason B

    2013-07-29

    Simple and versatile routes to the functionalization of uranyl-derived U(V)-oxo groups are presented. The oxo-lithiated, binuclear uranium(V)-oxo complexes [{(py)3LiOUO}2(L)] and [{(py)3LiOUO}(OUOSiMe3)(L)] were prepared by the direct combination of the uranyl(VI) silylamide "ate" complex [Li(py)2][(OUO)(N")3] (N" = N(SiMe3)2) with the polypyrrolic macrocycle H4L or the mononuclear uranyl (VI) Pacman complex [UO2(py)(H2L)], respectively. These oxo-metalated complexes display distinct U-O single and multiple bonding patterns and an axial/equatorial arrangement of oxo ligands. Their ready availability allows the direct functionalization of the uranyl oxo group leading to the binuclear uranium(V) oxo-stannylated complexes [{(R3Sn)OUO}2(L)] (R = nBu, Ph), which represent rare examples of mixed uranium/tin complexes. Also, uranium-oxo-group exchange occurred in reactions with [TiCl(OiPr)3] to form U-O-C bonds [{(py)3LiOUO}(OUOiPr)(L)] and [(iPrOUO)2(L)]. Overall, these represent the first family of uranium(V) complexes that are oxo-functionalised by Group 14 elements.

  1. Structural diversity in binuclear complexes of alkaline earth metal ions with 4,6-diacetylresorcinol

    Science.gov (United States)

    Shebl, Magdy; Khalil, Saied M. E.; Taha, A.; Mahdi, M. A. N.

    2012-11-01

    A new series of binuclear and mixed-ligand complexes with the general formula: [M 2(LO)yClz]; where M = Mg(II), Ca(II), Sr(II) and Ba(II); H2L = 4,6-diacetylresorcinol, the secondary ligand L' = acetylacetone (acac), 8-hydroxyquinoline (8-HQ) or 2,2'-bipyridyl (Bipy), n = 0-2, m = 1, 2, x = 0, 1, 2, 4, y = 0, 2, 4, 5 and z = 0-2; have been synthesized. They have been characterized by the analytical and spectral methods (IR, 1H NMR and mass) as well as TGA and molar conductivity measurements. The spectroscopic and conductance data suggested that the H2L ligand behaves as a neutral, monobasic or dibasic tetradentate ligand, depending on the basicity of the secondary ligand, through the two phenolic and two carbonyl groups. Binuclear octahedral geometry has been assigned to all of the prepared complexes in various molar ratios 2:2; 2:2:2; 1:2:1 and 1:2:4 (L:M:L'). Molecular orbital calculations were performed for the ligands and their complexes using Hyperchem 7.52 program on the bases of PM3 level and the results were correlated with the experimental data. The ligand and some of its alkaline metal(II) complexes showed antibacterial activity towards some of Gram-positive and Gram-negative bacteria, yeast (Candida albicans) and fungus (Aspergillus fumigatus).

  2. Synergy and destructive interferences between local magnetic anisotropies in binuclear complexes

    Energy Technology Data Exchange (ETDEWEB)

    Guihéry, Nathalie; Ruamps, Renaud [Laboratoire de Chimie et Physique Quantiques, UMR5625, University of Toulouse 3, Paul Sabatier, 118 route de Narbonne, 31062 Toulouse (France); Maurice, Rémi [SUBATECH, IN2P3/EMN Nantes/University of Nantes, 4 rue Alfred Kastler, BP 20722 44307, Nantes, Cedex 3 (France); Graaf, Coen de [University Rovira i Virgili, Marcelli Domingo s/n, 43007 Tarragona (Spain)

    2015-12-31

    Magnetic anisotropy is responsible for the single molecule magnet behavior of transition metal complexes. This behavior is characterized by a slow relaxation of the magnetization for low enough temperatures, and thus for a possible blocking of the magnetization. This bistable behavior can lead to possible technological applications in the domain of data storage or quantum computing. Therefore, the understanding of the microscopic origin of magnetic anisotropy has received a considerable interest during the last two decades. The presentation focuses on the determination of the anisotropy parameters of both mono-nuclear and bi-nuclear types of complexes and on the control and optimization of the anisotropic properties. The validity of the model Hamiltonians commonly used to characterize such complexes has been questioned and it is shown that neither the standard multispin Hamiltonian nor the giant spin Hamiltonian are appropriate for weakly coupled ions. Alternative models have been proposed and used to properly extract the relevant parameters. Rationalizations of the magnitude and nature of both local anisotropies of single ions and the molecular anisotropy of polynuclear complexes are provided. The synergy and interference effects between local magnetic anisotropies are studied in a series of binuclear complexes.

  3. A New Strategy for Architecture of Robust Monolayer Based on Binuclear Palladium (II) Complex of Calix[4]arene Derivative

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A monolayer which is formed by a binuclear palladium complex of low rim methionine-disubstituted calix[4]arene exhibits extraordinary cohesiveness. Cohesiveness measurement and Brewster Angle Microscopy observation show that the monolayer is uniform and robust. This film is probably formed by self-assembly of precursor complex through strong chloride ion bridge between palladium centers.

  4. Dimethylphosphinate bridged binuclear Rh(i) catalysts for the alkoxycarbonylation of aromatic C-H bonds.

    Science.gov (United States)

    Iturmendi, Amaia; Sanz Miguel, Pablo J; Popoola, Saheed A; Al-Saadi, Abdulaziz A; Iglesias, Manuel; Oro, Luis A

    2016-11-14

    A variety of binuclear rhodium(i) complexes featuring two bridging dimethylphosphinate ligands ((CH3)2PO2(-)) have been prepared and tested in the alkoxycarbonylation of aromatic C-H bonds. The complex [Rh(μ-κO,O'-(CH3)2PO2)(cod)]2 has been prepared by a reaction of [Rh(μ-MeO)(cod)]2 with 2 equivalents of dimethylphosphinic acid. Binuclear complexes [Rh(μ-κO,O'-(CH3)2PO2)(CO)L]2 (L = PPh3, P(OMe)Ph2 and P(OPh)3) were obtained by carbonylation of the related mononuclear complexes [Rh(κO-(CH3)2PO2)(cod)(L)], which were prepared in situ by the reaction of [Rh(μ-κO,O'-(CH3)2PO2)(cod)]2 with 2 equivalents of L. Conversely, if L = IPr, the reaction of [Rh(μ-κO,O'-(CH3)2PO2)(CO)L]2 with carbon monoxide affords the mononuclear complex [Rh(κO-(CH3)2PO2)(CO)2IPr]. The subsequent reaction with trimethylamine N-oxide gives the corresponding binuclear complex [Rh(μ-κO,O'-(CH3)2PO2)(CO)(IPr)]2 by abstraction of one of the carbonyl ligands. Complexes [Rh(μ-κO,O'-(CH3)2PO2)(cod)]2 and [Rh(κO-(CH3)2PO2)(cod)(L)] (L = IPr, PPh3, P(OMe)Ph2, P(OPh)3) are active precatalysts in the alkoxycarbonylation of C-H bonds, with the ligand system playing a key role in the catalytic activity. The complexes that feature more labile Rh-L bonds give rise to better catalysts, probably due to the more straightforward substitution of L by a second carbonyl ligand, since a more electrophilic carbonyl carbon atom is more susceptible toward aryl migration. In fact, complexes [Rh(μ-κO,O'-(CH3)2PO2)(CO)2]2 and [Rh(μ-Cl)(CO)2]2, generated in situ from [Rh(μ-κO,O'-(CH3)2PO2)(cod)]2 and [Rh(μ-Cl)(cod)2]2, respectively, are the most active catalysts tested in this work.

  5. Aging-related changes in the iron status of skeletal muscle.

    Science.gov (United States)

    DeRuisseau, Keith C; Park, Young-Min; DeRuisseau, Lara R; Cowley, Patrick M; Fazen, Christopher H; Doyle, Robert P

    2013-11-01

    The rise in non-heme iron (NHI) concentration observed in skeletal muscle of aging rodents is thought to contribute to the development of sarcopenia. The source of the NHI has not been identified, nor have the physiological ramifications of elevated iron status in aged muscle been directly examined. Therefore, we assessed plantaris NHI and heme iron (HI) levels in addition to expression of proteins involved in iron uptake (transferrin receptor-1; TfR1), storage (ferritin), export (ferroportin; FPN), and regulation (iron regulatory protein-1 (IRP1) and -2 (IRP2)) of male F344xBN F1 rats (n=10/group) of various ages (8, 18, 28, 32, and 36 months) to further understand iron regulation in aging muscle. In a separate experiment, iron chelator (pyridoxal isonicotinoyl hydrazone; PIH) or vehicle was administered to male F344xBN F1 rats (n=8/group) beginning at 30 months of age to assess the impact on plantaris muscle mass and function at ~36 months of age. Principle findings revealed the increased NHI concentration in old age was consistent with concentrating effects of muscle atrophy and reduction in HI levels, with no change in the total iron content of the muscle. The greatest increase in muscle iron content occurred during the period of animal growth and was associated with downregulation of TfR1 and IRP2 expression. Ferritin upregulation did not occur until senescence and the protein remained undetectable during the period of muscle iron content elevation. Lastly, administration of PIH did not significantly (p>0.05) impact NHI or measures of muscle atrophy or contractile function. In summary, this study confirms that the elevated NHI concentration in old age is largely due to the loss in muscle mass. The increased muscle iron content during aging does not appear to associate with cytosolic ferritin storage, but the functional consequences of elevated iron status in old age remains to be determined.

  6. Study on catalytic oxidation of planar binuclear copper phthalocyanine on 2-mercaptoethanol

    Institute of Scientific and Technical Information of China (English)

    CHEN Wenxing; WEI Lili; WANG Jinqian; YAO Yuyuan; L(U) Shenshui; CHEN Shiliang

    2006-01-01

    Mononuclear copper phthalocyanine (CuPc) and binuclear copper phthalocyanine (Cu2Pc2) were synthesized by the phenylanhydride-urea route, and their catalytic oxidation activity on 2-mercaptoethanol was studied. Based on the experimental results, a catalytic mechanism of Cu2Pc2 on 2-mercaptoethanol has been proposed. Furthermore, the effects of pH, Cu2Pc2 concentration, and temperature on the catalytic oxidation activity were evaluated. The results showed that CuPc has no catalytic activity, while Cu2Pc2 has high catalytic oxidation activity towards 2-mercaptoethanol with the optimal activity at pH 11. The reaction can further be enhanced by increasing Cu2Pc2 concentration and temperature, due to its endothermic characteristics.

  7. A binuclear Fe(III)Dy(III) single molecule magnet. Quantum effects and models.

    Science.gov (United States)

    Ferbinteanu, Marilena; Kajiwara, Takashi; Choi, Kwang-Yong; Nojiri, Hiroyuki; Nakamoto, Akio; Kojima, Norimichi; Cimpoesu, Fanica; Fujimura, Yuichi; Takaishi, Shinya; Yamashita, Masahiro

    2006-07-19

    The binuclear [FeIII(bpca)(mu-bpca)Dy(NO3)4], having Single Molecule Magnet (SMM) properties, belonging to a series of isostructural FeIIILnIII complexes (Ln = Eu, Gd, Tb, Dy, Ho) and closely related FeIILnIII chain structures, was characterized in concise experimental and theoretical respects. The low temperature magnetization data showed hysteresis and tunneling. The anomalous temperature dependence of Mössbauer spectra is related to the onset of magnetic order, consistent with the magnetization relaxation time scale resulting from AC susceptibility measurements. The advanced ab initio calculations (CASSCF and spin-orbit) revealed the interplay of ligand field, spin-orbit, and exchange effects and probed the effective Ising nature of the lowest states, involved in the SMM and tunneling effects.

  8. Determination of the catalytic activity of binuclear metallohydrolases using isothermal titration calorimetry.

    Science.gov (United States)

    Pedroso, Marcelo M; Ely, Fernanda; Lonhienne, Thierry; Gahan, Lawrence R; Ollis, David L; Guddat, Luke W; Schenk, Gerhard

    2014-03-01

    Binuclear metallohydrolases are a large and diverse family of enzymes that are involved in numerous metabolic functions. An increasing number of members find applications as drug targets or in processes such as bioremediation. It is thus essential to have an assay available that allows the rapid and reliable determination of relevant catalytic parameters (k cat, K m, and k cat/K m). Continuous spectroscopic assays are frequently only possible by using synthetic (i.e., nonbiological) substrates that possess a suitable chromophoric marker (e.g., nitrophenol). Isothermal titration calorimetry, in contrast, affords a rapid assay independent of the chromophoric properties of the substrate-the heat associated with the hydrolytic reaction can be directly related to catalytic properties. Here, we demonstrate the efficiency of the method on several selected examples of this family of enzymes and show that, in general, the catalytic parameters obtained by isothermal titration calorimetry are in good agreement with those obtained from spectroscopic assays.

  9. Synthesis and Crystal Structure of a Binuclear Gadolinium(Ⅲ) Complex Bridged by Cucurbit[6]uril

    Institute of Scientific and Technical Information of China (English)

    Gui Ling ZHANG; Zhi Yong WU; Yan Tuan LI; Da Qi WANG; Jian Min DOU

    2006-01-01

    A new cucurbit[6]uril bridged binuclear complex {[Gd(H2O)6]2[Q6(H2O)]}Cl6·4H2O,where Q6 represents cucurbit[6]uril, has been synthesized and characterized by X-ray diffraction.The crystal structure shows that the complex has an extended cucurbit[6]uril-bridged structure consisting of two gadolinium(Ⅲ) ions, in which each gadolinium(Ⅲ) ion is coordinated with two neighboring carbonylic oxygen atoms of Q6 and six oxygen atoms of water molecules that leans toward one side of the portal. One disordered guest water molecule resides in the Q6 molecule cavity and occupies two different positions. Hydrogen bonds assemble the complex to three-dimensional supramolecular structure.

  10. A binuclear molybdenum oxyfluoride: μ-oxido-bis[(2,2′-bipyridylfluoridodioxidomolybdenum(VI

    Directory of Open Access Journals (Sweden)

    Paul DeBurgomaster

    2010-08-01

    Full Text Available The title compound, [Mo2F2O5(C10H8N22], is a centrosymmetric binuclear molybdenum(VI species with the metal atoms in a distorted octahedral environment. The coordination geometries of the symmetry-equivalent molybdenum sites are defined by the cis-terminal oxide groups and the N-atom donors of the bipyridyl ligand in the equatorial plane with axial F and bridging O atoms. The bridging O atom occupies a center of symmetry. The molecules stack in the a-axis direction, and the crystal packing is stabilized by weak intra- and intermolecular C—H...O and C—H...F hydrogen bonds.

  11. Caco-2 cell acquisition of dietary iron(III invokes a nanoparticulate endocytic pathway.

    Directory of Open Access Journals (Sweden)

    Dora I A Pereira

    Full Text Available Dietary non-heme iron contains ferrous [Fe(II] and ferric [Fe(III] iron fractions and the latter should hydrolyze, forming Fe(III oxo-hydroxide particles, on passing from the acidic stomach to less acidic duodenum. Using conditions to mimic the in vivo hydrolytic environment we confirmed the formation of nanodisperse fine ferrihydrite-like particles. Synthetic analogues of these (~ 10 nm hydrodynamic diameter were readily adherent to the cell membrane of differentiated Caco-2 cells and internalization was visualized using transmission electron microscopy. Moreover, Caco-2 exposure to these nanoparticles led to ferritin formation (i.e., iron utilization by the cells, which, unlike for soluble forms of iron, was reduced (p=0.02 by inhibition of clathrin-mediated endocytosis. Simulated lysosomal digestion indicated that the nanoparticles are readily dissolved under mildly acidic conditions with the lysosomal ligand, citrate. This was confirmed in cell culture as monensin inhibited Caco-2 utilization of iron from this source in a dose dependent fashion (p<0.05 whilet soluble iron was again unaffected. Our findings reveal the possibility of an endocytic pathway for acquisition of dietary Fe(III by the small intestinal epithelium, which would complement the established DMT-1 pathway for soluble Fe(II.

  12. Synthesis of Three Novel Chiral Binuclear Mn(Ⅲ)-Schiff-base Complexes and the Application in Asymmetric Epoxidation of trans-Stilbene

    Institute of Scientific and Technical Information of China (English)

    Yang SUN; Ning TANG; Xin Wen LIU; Wei Sheng LIU

    2004-01-01

    Three novel chiral binuclear Mn(Ⅲ)-Schiff-base complexes have been synthesized and the application of these complexes in the asymmetric epoxidation of trans-stilbene is described, catalytic mechanism is also discussed briefly.

  13. Structure and nuclearity of active sites in Fe-zeolites: comparison with iron sites in enzymes and homogeneous catalysts.

    Science.gov (United States)

    Zecchina, Adriano; Rivallan, Mickaël; Berlier, Gloria; Lamberti, Carlo; Ricchiardi, Gabriele

    2007-07-21

    Fe-ZSM-5 and Fe-silicalite zeolites efficiently catalyse several oxidation reactions which find close analogues in the oxidation reactions catalyzed by homogeneous and enzymatic compounds. The iron centres are highly dispersed in the crystalline matrix and on highly diluted samples, mononuclear and dinuclear structures are expected to become predominant. The crystalline and robust character of the MFI framework has allowed to hypothesize that the catalytic sites are located in well defined crystallographic positions. For this reason these catalysts have been considered as the closest and best defined heterogeneous counterparts of heme and non heme iron complexes and of Fenton type Fe(2+) homogeneous counterparts. On this basis, an analogy with the methane monooxygenase has been advanced several times. In this review we have examined the abundant literature on the subject and summarized the most widely accepted views on the structure, nuclearity and catalytic activity of the iron species. By comparing the results obtained with the various characterization techniques, we conclude that Fe-ZSM-5 and Fe-silicalite are not the ideal samples conceived before and that many types of species are present, some active and some other silent from adsorptive and catalytic point of view. The relative concentration of these species changes with thermal treatments, preparation procedures and loading. Only at lowest loadings the catalytically active species become the dominant fraction of the iron species. On the basis of the spectroscopic titration of the active sites by using NO as a probe, we conclude that the active species on very diluted samples are isolated and highly coordinatively unsaturated Fe(2+) grafted to the crystalline matrix. Indication of the constant presence of a smaller fraction of Fe(2+) presumably located on small clusters is also obtained. The nitrosyl species formed upon dosing NO from the gas phase on activated Fe-ZSM-5 and Fe-silicalite, have been analyzed

  14. Binuclear zirconocene cations with μ-CH3-bridges in homogeneous Ziegler-Natta catalyst systems

    OpenAIRE

    Beck, Stefan; Prosenc, Marc-Heinrich; Brintzinger, Hans-Herbert; Goretzki, Ralf; Herfert, Norbert; Fink, Gerhard

    1996-01-01

    Binuclear zirconocene cations are observed by 1H-NMR in C6D6 solutions containing B(C6F5)3 and an excess of a zirconocene dimethyl complex. The CH3-bridged cation [((C5H5)2ZrCH3)2(μ-CH3)]+, solvent-separated from the anion H3CB(C6F5)−3, is present in equilibrium with (C5H5)2Zr(CH3)2 and the mononuclear ion pair [(C5H5)2ZrCH+3***H3CB(C6F5)−3]; in more concentrated solutions, a binuclear ion pair [((C5H5)2ZrCH3)2(μ-CH3)+***H3CB(C6F5)−3] is the dominant species. Similar equilibria are observe...

  15. Assessment of the role of α-lipoic acid against the oxidative stress of induced iron overload

    Directory of Open Access Journals (Sweden)

    Yasser F. Ali

    2015-01-01

    Full Text Available This work was aimed to study the protective role of α-lipoic acid against the oxidative damage of induced iron overload. Iron (Fe overload is a complication of the treatment, by chronic transfusion, of a number of genetic diseases associated with inadequate red cell production (anemias and of other genetic diseases that lead to excessive iron absorption from the diet. Male rats were injected ip with 5 mg/kg body weight ferrous sulfate for 50 days. The animals were injected ip with α-lipoic acid 20 mg per kg body weight for 21 days. Serum iron, Total Iron Binding Capacity (TIBC, Malonyldialdehyde (MDA, Electron paramagnetic resonance (EPR spectroscopy, UV-visible absorption spectrum of hemoglobin and osmotic fragility were studied. Results showed significant increase in serum iron, total iron binding capacity, and malonyldialdehyde levels in iron-loaded rats. Treatment with lipoic acid (LA resulted in decreasing serum iron and TIBC levels by 47%and 29% respectively. At the same time the lipoic acid decreased the level of the MDA in liver, brain and plasma by 54%, 42% and 74% respectively. Also LA diminished the effect of iron-induced free radicals on erythrocyte membrane integrity; it decreased the elevated average osmotic fragility and decreased the elevated rate of hemolysis. Results from UV-visible spectrophotometric measurement of hemoglobin revealed that no oxidative changes of hemoglobin occurred in iron-loaded rats. EPR spectra showed increased in non-heme ferric ions Fe+3 and free radicals in iron-loaded rats. Whereas the injection of the lipoic acid leads to decreased in such toxic result. In conclusion, these observations suggested that lipoic acid might be a beneficial antioxidant that can be effective for limiting damage from oxidative stress of iron overload.

  16. Synthesis and Structural Determination of Binuclear Nine-Coordinate K4[Y2(Httha)2]·14H2O

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A Y3+ complex with triethylenetetraaminehexaacetic acid was prepared and its composition and structure were determined as K4[Y2(Httha)2]*14H2O by elemental analysis and single-crystal X-ray four circle diffraction analysis. In the binuclear complex, the two YN3O6 parts all form nine-coordinate monocapped square anti prismatic structures. There are a lot of water molecules in the unit cell which form hydrogen bonds.

  17. The synthesis and characterization of organometallic copolymers with Mn-Re binuclear transition-metal group in the side chain

    Institute of Scientific and Technical Information of China (English)

    XU; Zhi; FENG; Gang; BAI; Zhifeng; MA; Yongqiang; CHANG; Weixing; LI; Jing

    2006-01-01

    Novel organometallic copolymers with Mn-Re binuclear transition-metal groups in the side chain are synthesized and characterized. The structure and properties of the copolymers are characterized by GPC, DSC, TG, NMR, FT-IR, UV-Vis spectra and elemental analysis. The glass transition temperature and UV-Vis spectra properties of these three organometallic copolymers are found to be different from the normal polystyrene. New synthetic strategy for the synthesis of organometallic copolymer is developed.

  18. Electrocatalytic oxidation of methanol at platinum electrode modified with Eu-Fe cyanide-bridged binuclear complexes

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The electrocatalytic oxidation of methanol at the platinum electrode modified with Eu-Fe cyanide-bridged binuclear complexes (Eu-Fe film) was investigated for the first time by cyclic voltammetry.Compared with the bare platinum electrode,the results showed that the modified electrode had excellent electrocatalytic activity for the oxidation of methanol;the oxidation peak potential shifted more negatively and the peak current increased about twenty times.The electrooxidation of methanol at the modified el...

  19. Lipidomic analysis links mycobactin synthase K to iron uptake and virulence in M. tuberculosis.

    Directory of Open Access Journals (Sweden)

    Cressida A Madigan

    2015-03-01

    Full Text Available The prolonged survival of Mycobacterium tuberculosis (M. tb in the host fundamentally depends on scavenging essential nutrients from host sources. M. tb scavenges non-heme iron using mycobactin and carboxymycobactin siderophores, synthesized by mycobactin synthases (Mbt. Although a general mechanism for mycobactin biosynthesis has been proposed, the biological functions of individual mbt genes remain largely untested. Through targeted gene deletion and global lipidomic profiling of intact bacteria, we identify the essential biochemical functions of two mycobactin synthases, MbtK and MbtN, in siderophore biosynthesis and their effects on bacterial growth in vitro and in vivo. The deletion mutant, ΔmbtN, produces only saturated mycobactin and carboxymycobactin, demonstrating an essential function of MbtN as the mycobactin dehydrogenase, which affects antigenicity but not iron uptake or M. tb growth. In contrast, deletion of mbtK ablated all known forms of mycobactin and its deoxy precursors, defining MbtK as the essential acyl transferase. The mbtK mutant showed markedly reduced iron scavenging and growth in vitro. Further, ΔmbtK was attenuated for growth in mice, demonstrating a non-redundant role of hydroxamate siderophores in virulence, even when other M. tb iron scavenging mechanisms are operative. The unbiased lipidomic approach also revealed unexpected consequences of perturbing mycobactin biosynthesis, including extreme depletion of mycobacterial phospholipids. Thus, lipidomic profiling highlights connections among iron acquisition, phospholipid homeostasis, and virulence, and identifies MbtK as a lynchpin at the crossroads of these phenotypes.

  20. Synthesis, structure and photophysical properties of a binuclear Zn(II) complex based on 8-hydroxyquinoline ligand with naphthyl unit

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Guozan, E-mail: yuanguozan@163.com [School of Chemistry and Chemical Engineering, Anhui University of Technology, Maanshan 243002 (China); State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, Fujian (China); Shan, Weilong; Chen, Jiangbo; Tian, Yulan; Wang, Haitao [School of Chemistry and Chemical Engineering, Anhui University of Technology, Maanshan 243002 (China)

    2015-04-15

    A 2-substituted-8-hydroxyquinoline ligand (E)-2-[2-naphthyl-ethenyl]-8-hydroxyquinoline (HL) was synthesized and characterized by LC–MS, NMR spectroscopy, elemental analysis and single-crystal X-ray diffraction. Using a solvothermal method, a binuclear complex [Zn{sub 2}L{sub 4}] (1) was fabricated by self-assembly of Zn(II) ion with ligand HL. X-ray structural analysis shows that the binuclear Zn(II) units are linked into 1D chain along the b axis via aromatic stacking. The coordination assembly of zinc salt and HL in solutions was investigated by UV–vis and photoluminescence (PL). Additionally, we also studied the thermal stability and photophysical properties of (fluorescent emission and lifetime) complex 1. The experimental results show that the complex 1 emits yellow luminescence in the solid state. - Highlights: • Ligand HL and binuclear complex 1 were synthesized and characterized. • Complex 1 features a 2D network constructed by non-covalent interactions. • Complex 1 emits yellow luminescence in the solid state.

  1. Accurate computation and interpretation of spin-dependent properties in metalloproteins

    Science.gov (United States)

    Rodriguez, Jorge

    2006-03-01

    Nature uses the properties of open-shell transition metal ions to carry out a variety of functions associated with vital life processes. Mononuclear and binuclear iron centers, in particular, are intriguing structural motifs present in many heme and non-heme proteins. Hemerythrin and methane monooxigenase, for example, are members of the latter class whose diiron active sites display magnetic ordering. We have developed a computational protocol based on spin density functional theory (SDFT) to accurately predict physico-chemical parameters of metal sites in proteins and bioinorganic complexes which traditionally had only been determined from experiment. We have used this new methodology to perform a comprehensive study of the electronic structure and magnetic properties of heme and non-heme iron proteins and related model compounds. We have been able to predict with a high degree of accuracy spectroscopic (Mössbauer, EPR, UV-vis, Raman) and magnetization parameters of iron proteins and, at the same time, gained unprecedented microscopic understanding of their physico-chemical properties. Our results have allowed us to establish important correlations between the electronic structure, geometry, spectroscopic data, and biochemical function of heme and non- heme iron proteins.

  2. Electrochemistry of Simple Organometallic Models of Iron-Iron Hydrogenases in Organic Solvent and Water.

    Science.gov (United States)

    Gloaguen, Frederic

    2016-01-19

    Synthetic models of the active site of iron-iron hydrogenases are currently the subjects of numerous studies aimed at developing H2-production catalysts based on cheap and abundant materials. In this context, the present report offers an electrochemist's view of the catalysis of proton reduction by simple binuclear iron(I) thiolate complexes. Although these complexes probably do not follow a biocatalytic pathway, we analyze and discuss the interplay between the reduction potential and basicity and how these antagonist properties impact the mechanisms of proton-coupled electron transfer to the metal centers. This question is central to any consideration of the activity at the molecular level of hydrogenases and related enzymes. In a second part, special attention is paid to iron thiolate complexes holding rigid and unsaturated bridging ligands. The complexes that enjoy mild reduction potentials and stabilized reduced forms are promising iron-based catalysts for the photodriven evolution of H2 in organic solvents and, more importantly, in water.

  3. Iron Acquisition Pathways as Targets for Antitubercular Drugs.

    Science.gov (United States)

    Meneghetti, Fiorella; Villa, Stefania; Gelain, Arianna; Barlocco, Daniela; Chiarelli, Laurent Roberto; Pasca, Maria Rosalia; Costantino, Luca

    2016-01-01

    Tuberculosis nowadays ranks as the second leading cause of death from an infectious disease worldwide. In the last twenty years, this disease has again started to spread mainly for the appearance of multi-drug resistant forms. Therefore, new targets are needed to address the growing emergence of bacterial resistance and for antitubercular drug development. Efficient iron acquisition is crucial for the pathogenesis of Mycobacterium tuberculosis, because it serves as cofactor in many essential biological processes, including DNA biosynthesis and cellular respiration. Bacteria acquire iron chelating non-heme iron from the host using the siderophore mycobactins and carboxymycobactins and by the uptake of heme iron released by damaged red blood cells, through several acquisition systems. Drug discovery focused its efforts on the inhibition of MbtI and MbtA, which are are two enzymes involved in the mycobactin biosynthetic pathway. In particular, MbtI inhibitors have been studied in vitro, while MbtA inhibitors showed activity also in infected mice. Another class of compounds, MmpL3 inhibitors, showed antitubercular activity in vitro and in vivo, but their mechanism of action seems to be off-target. Some compounds inhibiting 4'-phosphopantetheinyl transferase were discovered but not tested on in vivo assays. The available data reported in this study based on inhibitors and gene deletion studies, suggest that targeting iron acquisition systems could be considered a promising antitubercular strategy. Due to their redundancy, the relative importance of each pathway for Mycobacterium tuberculosis survival has still to be determined. Thus, in vivo studies with new, potent and specific inhibitors are needed to highlight target selection.

  4. Pyrolyzed binuclear-cobalt-phthalocyanine as electrocatalyst for oxygen reduction reaction in microbial fuel cells.

    Science.gov (United States)

    Li, Baitao; Wang, Mian; Zhou, Xiuxiu; Wang, Xiujun; Liu, Bingchuan; Li, Baikun

    2015-10-01

    A novel platinum (Pt)-free cathodic materials binuclear-cobalt-phthalocyanine (Bi-CoPc) pyrolyzed at different temperatures (300-1000 °C) were examined as the oxygen reduction reaction (ORR) catalysts, and compared with unpyrolyzed Bi-CoPc/C and Pt cathode in single chamber microbial fuel cells (SCMFCs). The results showed that the pyrolysis process increased the nitrogen abundance on Bi-CoPc and changed the nitrogen types. The Bi-CoPc pyrolyzed at 800 °C contained a significant amount of pyrrolic-N, and exhibited a high electrochemical catalytic activity. The power density and current density increased with temperature: Bi-CoPc/C-800 > Bi-CoPc/C-1000 > Bi-CoPc/C-600 > Bi-CoPc/C-300 > Bi-CoPc/C. The SCMFC with Bi-CoPc/C-800 cathode had a maximum power density of 604 mW m(-2). The low cost Bi-CoPc compounds developed in this study showed a potential in air-breathing MFC systems, with the proper pyrolysis temperature being chosen.

  5. A Novel Binuclear Cu(Ⅱ) Complex with Nitroxide Radicals Exhibiting Ferromagnetic Interactions

    Institute of Scientific and Technical Information of China (English)

    刘尚远; 陈毅雯; 高东昭

    2012-01-01

    A new binuclear Cu(Ⅱ) complex with nitronyl nitroxide radicals [Cu(NIT3Py)2Cl2]2(NIT3Py = 2-(3'-pyridinyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) has been synthesized and structurally characterized by X-ray diffraction analysis.It crystallizes in monoclinic,space group C2/c with a = 38.483(4),b = 7.2450(8),c = 27.559(3) ,β = 134.0180(10)°,V = 5525.6(10) 3,C48H64Cl4Cu2N12O8,Mr = 1206.00,Z = 4,Dc = 1.450 g/cm3,μ(MoKα) = 1.025 mm-1,F(000) = 2504,S = 1.066,the final R = 0.0471 and wR = 0.1121 for 3286 observed reflections(I 2σ(I)).The title complex consists of centrosymmetric dinuclear units [Cu(NIT3Py)2Cl2]2,in which the copper ions are square-pyramidally coordinated by two pyridyl nitrogen atoms of two radical ligands and three chlorine anions,two of which bridge the copper ions.The magnetic measurements show ferromagnetic interactions between the copper ions and the radical ligands.

  6. Synthesis and antitumor activity of iodo-bridged-binuclear platinum complex

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Iodo-bridged binuclear platinum(II) com- plex[Pt((◇)-NH2)I2]2(BPA) has been synthesized and characterized by elemental analysis, conductivity, differential thermal analysis, IR, UV and 1HNMR spectra techniques. The cytotoxicity of the complex was tested by MTT and SRB assays. The results show that complex BPA demonstrates better cytotoxicity than that of the clinically established cisplatin against EJ, HCT-8, BGC-823, HL-60 and MCF-7 cell lines. The complex BPA at concentrations of 1.00 and 2.00 μmol/L induces G1 cell cycle arrest in HL-60 cells. The level of total platinum bound to DNA in HL-60 cells is significantly higher than that of cisplatin under the same experimental conditions. Acute toxicity experimental results indiacte that LD50 of BPA is 815.3 mg/kg by intraperitoneal administration. BPA at dose of 12 mg/kg significantly inhibits the growth of nude mice implanted by human A2780 and HCT-116 carcinomas, and inhibition rate is similar to that of cisplatin at dose of 4 mg/kg by intraperitoneal administration. BPA at dose of 20 mg/kg inhibits the growth of nude mice implanted by human A549 carcinomas, but there was no significant statistical difference.

  7. Effect of cerebral amyloid angiopathy on brain iron, copper, and zinc in Alzheimer's disease.

    Science.gov (United States)

    Schrag, Matthew; Crofton, Andrew; Zabel, Matthew; Jiffry, Arshad; Kirsch, David; Dickson, April; Mao, Xiao Wen; Vinters, Harry V; Domaille, Dylan W; Chang, Christopher J; Kirsch, Wolff

    2011-01-01

    Cerebral amyloid angiopathy (CAA) is a vascular lesion associated with Alzheimer's disease (AD) present in up to 95% of AD patients and produces MRI-detectable microbleeds in many of these patients. It is possible that CAA-related microbleeding is a source of pathological iron in the AD brain. Because the homeostasis of copper, iron, and zinc are so intimately linked, we determined whether CAA contributes to changes in the brain levels of these metals. We obtained brain tissue from AD patients with severe CAA to compare to AD patients without evidence of vascular amyloid-β. Patients with severe CAA had significantly higher non-heme iron levels. Histologically, iron was deposited in the walls of large CAA-affected vessels. Zinc levels were significantly elevated in grey matter in both the CAA and non-CAA AD tissue, but no vascular staining was noted in CAA cases. Copper levels were decreased in both CAA and non-CAA AD tissues and copper was found to be prominently deposited on the vasculature in CAA. Together, these findings demonstrate that CAA is a significant variable affecting transition metals in AD.

  8. Heme iron uptake by Caco-2 cells is a saturable, temperature sensitive and modulated by extracellular pH and potassium.

    Science.gov (United States)

    Arredondo, Miguel; Kloosterman, Janneke; Núñez, Sergio; Segovia, Fabián; Candia, Valeria; Flores, Sebastián; Le Blanc, Solange; Olivares, Manuel; Pizarro, Fernando

    2008-11-01

    It is known that heme iron and inorganic iron are absorbed differently. Heme iron is found in the diet mainly in the form of hemoglobin and myoglobin. The mechanism of iron absorption remains uncertain. This study focused on the heme iron uptake by Caco-2 cells from a hemoglobin digest and its response to different iron concentrations. We studied the intracellular Fe concentration and the effect of time, K+ depletion, and cytosol acidification on apical uptake and transepithelial transport in cells incubated with different heme Fe concentrations. Cells incubated with hemoglobin-digest showed a lower intracellular Fe concentration than cells grown with inorganic Fe. However, uptake and transepithelial transport of Fe was higher in cells incubated with heme Fe. Heme Fe uptake had a low Vmax and Km as compared to inorganic Fe uptake and did not compete with non-heme Fe uptake. Heme Fe uptake was inhibited in cells exposed to K+ depletion or cytosol acidification. Heme oxygenase 1 expression increased and DMT1 expression decreased with higher heme Fe concentrations in the media. The uptake of heme iron is a saturable and temperature-dependent process and, therefore, could occur through a mechanism involving both a receptor and the endocytic pathway.

  9. One-dimensional Polymers Constructed with Binuclear Copper(Ⅱ) α,β-Unsaturated Carboxylates Bridged by 4,4'-Bipyridine

    Institute of Scientific and Technical Information of China (English)

    刘萍; 王尧宇; 李东升; 栾新军; 高松; 史启祯

    2005-01-01

    A methanol solution of 4,4'-bipyridine reacts with Cu2A4(H2O)2 to yield coordination polymers of general formula: [Cu2A4(bipy)]n [A: CH2=C(Me)CO2- (1), CH2=CHCO2- (2); bipy: 4,4'-bipyridine]. They were characterized by elemental analyses, IR spectra and thermal analyses. The X-ray structure analyses of 1 show a one-dimensional chain structure where the binuclear structural units Cu2[CH2=C(Me)CO2]4 are bridged by 4,4'-bipyridine molecules. Furthermore, the binuclear units between adjacent layers can form micropores. The temperature-dependent magnetic susceptibility of 1 indicates that the strong antiferromagnetic interaction exists between copper(Ⅱ) atoms in the binuclear units.

  10. Iron repletion relocalizes hephaestin to a proximal basolateral compartment in polarized MDCK and Caco2 cells

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Seung-Min [Department of Biological Sciences, University of Columbia, NY (United States); Department of Nutritional Science and Toxicology, University of California, Berkeley, CA (United States); Attieh, Zouhair K. [Department of Laboratory Science and Technology, American University of Science and Technology, Ashrafieh (Lebanon); Department of Nutritional Science and Toxicology, University of California, Berkeley, CA (United States); Son, Hee Sook [Department of Food Science and Human Nutrition, College of Human Ecology, Chonbuk National University (Korea, Republic of); Department of Nutritional Science and Toxicology, University of California, Berkeley, CA (United States); Chen, Huijun [Medical School, Nanjing University, Nanjing 210008, Jiangsu Province (China); Department of Nutritional Science and Toxicology, University of California, Berkeley, CA (United States); Bacouri-Haidar, Mhenia [Department of Biology, Faculty of Sciences (I), Lebanese University, Hadath (Lebanon); Department of Nutritional Science and Toxicology, University of California, Berkeley, CA (United States); Vulpe, Chris D., E-mail: vulpe@berkeley.edu [Department of Nutritional Science and Toxicology, University of California, Berkeley, CA (United States)

    2012-05-11

    Highlights: Black-Right-Pointing-Pointer Hephaestin localizes in the perinuclear space in non-polarized cells. Black-Right-Pointing-Pointer Hephaestin localizes in the perinuclear space in iron deficient and polarized cells. Black-Right-Pointing-Pointer Hephaestin with apical iron moves near to basolateral membrane of polarized cells. Black-Right-Pointing-Pointer Peri-basolateral location of hephaestin is accessible to the extracellular space. Black-Right-Pointing-Pointer Hephaestin is involved in iron mobilization from the intestine to circulation. -- Abstract: While intestinal cellular iron entry in vertebrates employs multiple routes including heme and non-heme routes, iron egress from these cells is exclusively channeled through the only known transporter, ferroportin. Reduced intestinal iron export in sex-linked anemia mice implicates hephaestin, a ferroxidase, in this process. Polarized cells are exposed to two distinct environments. Enterocytes contact the gut lumen via the apical surface of the cell, and through the basolateral surface, to the body. Previous studies indicate both local and systemic control of iron uptake. We hypothesized that differences in iron availability at the apical and/or basolateral surface may modulate iron uptake via cellular localization of hephaestin. We therefore characterized the localization of hephaestin in two models of polarized epithelial cell lines, MDCK and Caco2, with varying iron availability at the apical and basolateral surfaces. Our results indicate that hephaestin is expressed in a supra-nuclear compartment in non-polarized cells regardless of the iron status of the cells and in iron deficient and polarized cells. In polarized cells, we found that both apical (as FeSO{sub 4}) and basolateral iron (as the ratio of apo-transferrin to holo-transferrin) affect mobilization of hephaestin from the supra-nuclear compartment. We find that the presence of apical iron is essential for relocalization of hephaestin to a

  11. Post-divorce custody arrangements and binuclear family structures of Flemish adolescents

    Directory of Open Access Journals (Sweden)

    An Katrien Sodermans

    2013-03-01

    Full Text Available BACKGROUND Because of the tendency towards equal parental rights in post-divorce custody decisions, the number of children living partially in two households after divorce has increased. Because of this evolution, traditional family typologies have been challenged. OBJECTIVE In this study, we want to describe the post-divorce custody arrangements and family configurations of Flemish adolescents (between 12 and 18 years old. METHODS We use four waves of the Leuven Adolescents and Families Study, a yearly survey in which adolescents are questioned at school about their family life, family relationships and various dimensions of their wellbeing. Our research sample consists of 1525 adolescents who experienced a parental break-up. First, we present information on the proportion of adolescents in different custody arrangements, according to divorce cohort, age and sex. Next, we describe post-divorce family configurations, according to the custody arrangement and different criteria of co-residence between children and step-parents. RESULTS We observe a higher proportion of adolescents spending at least 33Š of time in both parental households (shared residence for more recent divorce cohorts. A large proportion of adolescents is living with a new partner of the mother or father, but there are important differences, according to the criteria used to define stepfamily configurations. CONCLUSIONS The relatively high incidence figures of children in shared residence challenge the current dichotomous post-divorce family concept in terms of single parent families and stepfamilies. Family typologies applying a binuclear perspective are therefore increasingly meaningful and necessary. In addition, shared residence increases the chance of co-residence with at least one step-parent, and increases the proportion of children with a part-time residential stepmother.

  12. Iron deficiency.

    Science.gov (United States)

    Scrimshaw, N S

    1991-10-01

    The world's leading nutritional problem is iron deficiency. 66% of children and women aged 15-44 years in developing countries have it. Further, 10-20% of women of childbearing age in developed countries are anemic. Iron deficiency is identified with often irreversible impairment of a child's learning ability. It is also associated with low capacity for adults to work which reduces productivity. In addition, it impairs the immune system which reduces the body's ability to fight infection. Iron deficiency also lowers the metabolic rate and the body temperature when exposed to cold. Hemoglobin contains nearly 73% of the body's iron. This iron is always being recycled as more red blood cells are made. The rest of the needed iron does important tasks for the body, such as binds to molecules that are reservoirs of oxygen for muscle cells. This iron comes from our diet, especially meat. Even though some plants, such as spinach, are high in iron, the body can only absorb 1.4-7% of the iron in plants whereas it can absorb 20% of the iron in red meat. In many developing countries, the common vegetarian diets contribute to high rates of iron deficiency. Parasitic diseases and abnormal uterine bleeding also promote iron deficiency. Iron therapy in anemic children can often, but not always, improve behavior and cognitive performance. Iron deficiency during pregnancy often contributes to maternal and perinatal mortality. Yet treatment, if given to a child in time, can lead to normal growth and hinder infections. However, excess iron can be damaging. Too much supplemental iron in a malnourished child promotes fatal infections since the excess iron is available for the pathogens use. Many countries do not have an effective system for diagnosing, treating, and preventing iron deficiency. Therefore a concerted international effort is needed to eliminate iron deficiency in the world.

  13. Oxidative demethylation in monooxygenase model systems. Competing pathways for binuclear and helical multinuclear copper(I) complexes

    NARCIS (Netherlands)

    Gelling, O.J.; Feringa, Bernard

    1990-01-01

    The ligand 2,6-bis[N-(2-pyridylethyl)formimidoyl]-1-methoxybenzene (2,6-BPB-1-OCH3) (4) reacts with Cu(CH3CN)4BF4 to form novel binuclear copper(I) complexes [Cu2(2,6-BPB-1-OCH3)(BF4)2(CH3CN)4] (11) and [Cu2(2,6-BPB-1-OCH3)(BF4)2(CH2Cl2)0.5] (14), or the helical polynuclear copper(1) complex [Cu(2,6

  14. Novel planar binuclear zinc phthalocyanine sensitizer for dye-sensitized solar cells: Synthesis and spectral, electrochemical, and photovoltaic properties

    Science.gov (United States)

    Zhu, Baiqing; Zhang, Xuejun; Han, Mingliang; Deng, Pengfei; Li, Qiaoling

    2015-01-01

    A planar binuclear zinc phthalocyanine was newly synthesized for use in dye-sensitized solar cells, based on Schiff base and asymmetric amino zinc phthalocyanine. The novel compounds were characterized using FTIR, UV-Vis, 1H NMR, cyclic voltammetry and elemental analysis. From the reduction and oxidation behavior, it is proved that APC and bi-NPC have negative LUMO levels and positive HOMO levels, satisfying the energy gap rule, and can be employed as sensitizers for dye-sensitized solar cells (DSSCs) applications.

  15. Substrate-promoted formation of a catalytically competent binuclear center and regulation of reactivity in a glycerophosphodiesterase from Enterobacter aerogenes.

    Science.gov (United States)

    Hadler, Kieran S; Tanifum, Eric A; Yip, Sylvia Hsu-Chen; Mitić, Natasa; Guddat, Luke W; Jackson, Colin J; Gahan, Lawrence R; Nguyen, Kelly; Carr, Paul D; Ollis, David L; Hengge, Alvan C; Larrabee, James A; Schenk, Gerhard

    2008-10-29

    The glycerophosphodiesterase (GpdQ) from Enterobacter aerogenes is a promiscuous binuclear metallohydrolase that catalyzes the hydrolysis of mono-, di-, and triester substrates, including some organophosphate pesticides and products of the degradation of nerve agents. GpdQ has attracted recent attention as a promising enzymatic bioremediator. Here, we have investigated the catalytic mechanism of this versatile enzyme using a range of techniques. An improved crystal structure (1.9 A resolution) illustrates the presence of (i) an extended hydrogen bond network in the active site, and (ii) two possible nucleophiles, i.e., water/hydroxide ligands, coordinated to one or both metal ions. While it is at present not possible to unambiguously distinguish between these two possibilities, a reaction mechanism is proposed whereby the terminally bound H2O/OH(-) acts as the nucleophile, activated via hydrogen bonding by the bridging water molecule. Furthermore, the presence of substrate promotes the formation of a catalytically competent binuclear center by significantly enhancing the binding affinity of one of the metal ions in the active site. Asn80 appears to display coordination flexibility that may modulate enzyme activity. Kinetic data suggest that the rate-limiting step occurs after hydrolysis, i.e., the release of the phosphate moiety and the concomitant dissociation of one of the metal ions and/or associated conformational changes. Thus, it is proposed that GpdQ employs an intricate regulatory mechanism for catalysis, where coordination flexibility in one of the two metal binding sites is essential for optimal activity.

  16. Binuclear Cu(II and Co(II Complexes of Tridentate Heterocyclic Shiff Base Derived from Salicylaldehyde with 4-Aminoantipyrine

    Directory of Open Access Journals (Sweden)

    Omar Hamad Shihab Al-Obaidi

    2012-01-01

    Full Text Available New binuclear Co(II and Co(II complexes of ONO tridentate heterocyclic Schiff base derived from 4-aminoantipyrine with salicylaldehyde have been synthesized and characterized on the bases of elemental analysis, UV-Vis., FT-IR, and also by aid of molar conductivity measurements, magnetic measurements, and melting points. It has been found that the Schiff bases with Cu(II or Co(II ion forming binuclear complexes on (1 : 1 “metal : ligand” stoichiometry. The molar conductance measurements of the complexes in DMSO correspond to be nonelectrolytic nature for all prepared complexes. Distorted octahedral environment is suggested for metal complexes. A theoretical treatment of the formation of complexes in the gas phase was studied, and this was done by using the HyperChem-6 program for the molecular mechanics and semi-empirical calculations. The free ligand and its complexes have been tested for their antibacterial activities against two types of human pathogenic bacteria: the first type (Staphylococcus aureus is Gram positive and the second type (Escherichia coli is Gram negative (by using agar well diffusion method. Finally, it was found that compounds show different activity of inhibition on growth of the bacteria.

  17. Crystal Structure of Phosphatidylglycerophosphatase (PGPase), a Putative Membrane-Bound Lipid Phosphatase, Reveals a Novel Binuclear Metal Binding Site and Two Proton Wires

    Energy Technology Data Exchange (ETDEWEB)

    Kumaran,D.; Bonnano, J.; Burley, S.; Swaminathan, S.

    2006-01-01

    Phosphatidylglycerophosphatase (PGPase), an enzyme involved in lipid metabolism, catalyzes formation of phosphatidylglycerol from phosphatidylglycerophosphate. Phosphatidylglycerol is a multifunctional phospholipid, found in the biological membranes of many organisms. Here, we report the crystal structure of Listeria monocytogenes PGPase at 1.8 Angstroms resolution. PGPase, an all-helical molecule, forms a homotetramer. Each protomer contains an independent active site with two metal ions, Ca{sup 2+} and Mg{sup 2+}, forming a hetero-binuclear center located in a hydrophilic cavity near the surface of the molecule. The binuclear center, conserved ligands, metal-bound water molecules, and an Asp-His dyad form the active site. The catalytic mechanism of this enzyme is likely to proceed via binuclear metal activated nucleophilic water. The binuclear metal-binding active-site environment of this structure should provide insights into substrate binding and metal-dependent catalysis. A long channel with inter-linked linear water chains, termed 'proton wires', is observed at the tetramer interface. Comparison of similar water chain structures in photosynthetic reaction centers (RCs), Cytochrome f, gramicidin, and bacteriorhodopsin, suggests that PGPase may conduct protons via proton wires.

  18. Six Zn(II) and Cd(II) coordination polymers assembled from a similar binuclear building unit: tunable structures and luminescence properties.

    Science.gov (United States)

    Zhang, Liyan; Rong, Lulu; Hu, Guoli; Jin, Suo; Jia, Wei-Guo; Liu, Ji; Yuan, Guozan

    2015-04-21

    Six Zn(ii) and Cd(ii) coordination polymers were constructed by treating a 2-substituted 8-hydroxyquinolinate ligand containing a pyridyl group with zinc or cadmium salts, and characterized by a variety of techniques. Interestingly, based on a similar binuclear Zn(ii) or Cd(ii) building unit, the supramolecular structures of the six coordination polymers () exhibit an unprecedented structural diversification due to the different choices of metal salts. and represent a novel 2D framework containing 1D infinite right- and left-handed helical chains. and are 2D coordination frameworks based on binuclear Cd(ii) building units. For and , the L ligands can bridge binuclear building units forming a 1D infinite chain. Interestingly, the adjacent Cd2O2 planes of the 1D chain in are in parallel with each other, while the dihedral angle between the two Zn2O2 planes in is 83.43°. Photoluminescence properties revealed that the six coordination polymers exhibit redshifted emission maximum compared with the free ligand HL, which can be ascribed to an increased conformational rigidity and the fabrication of coplanar binuclear building units M2L2 in . Coordination polymers also display distinct fluorescence lifetimes and quantum yields because of their different metal centers and supramolecular structures.

  19. Iron Homeostasis and Nutritional Iron Deficiency123

    OpenAIRE

    2011-01-01

    Nonheme food ferritin (FTN) iron minerals, nonheme iron complexes, and heme iron contribute to the balance between food iron absorption and body iron homeostasis. Iron absorption depends on membrane transporter proteins DMT1, PCP/HCP1, ferroportin (FPN), TRF2, and matriptase 2. Mutations in DMT1 and matriptase-2 cause iron deficiency; mutations in FPN, HFE, and TRF2 cause iron excess. Intracellular iron homeostasis depends on coordinated regulation of iron trafficking and storage proteins enc...

  20. Gastric digestion of pea ferritin and modulation of its iron bioavailability by ascorbic and phytic acids in caco-2 cells

    Institute of Scientific and Technical Information of China (English)

    Satyanarayana Bejjani; Raghu Pullakhandam; Ravinder Punjal; K Madhavan Nair

    2007-01-01

    AIM: To understand the digestive stability and mechanism of release and intestinal uptake of pea ferritin iron in caco-2 cell line model.METHODS: Pea seed ferritin was purified using salt fractionation followed by gel filtration chromatography.The bioavailability of ferritin iron was assessed using coupled in vitro digestion/Caco-2 cell model in the presence or absence of ascorbic acid and phytic acid.Caco-2 cell ferritin formation was used as a surrogate marker of iron uptake. Structural changes of pea ferritin under simulated gastric pH were characterized using electrophoresis, gel filtration and circular dichroism spectroscopy.RESULTS: The caco-2 cell ferritin formation was significantly increased (P < 0.001) with FeSO4 (19.3±9.8 ng/mg protein) and pea ferritin (13.9 ± 6.19 ng/mg protein) compared to the blank digest (3.7 ± 1.8 ng/mg protein). Ascorbic acid enhanced while phytic acid decreased the pea ferritin iron bioavailability. However,either in the presence or absence of ascorbic acid, the ferritin content of caco-2 cells was significantly less with pea ferritin than with FeSO4. At gastric pH, no band corresponding to ferritin was observed in the presence of pepsin either on native PAGE or SDS-PAGE. Gel filtration chromatography and circular dichroism spectroscopy revealed a pH dependent loss of quaternary and secondary structure.CONCLUSION: Under gastric conditions, the iron core of pea ferritin is released into the digestive medium due to acid induced structural alterations and dissociation of protein. The released iron interacts with dietary factors leading to modulation of pea ferritin iron bioavailability,resembling the typical characteristics of non-heme iron.

  1. Spectral and Electroluminescent Properties of Binuclear Zinc Complexes with Halogen-Substituted Derivatives of 1,2,4-Triazole

    Science.gov (United States)

    Kopylova, T. N.; Degtyarenko, K. M.; Samsonova, L. G.; Gadirov, R. M.; Gusev, A. N.; Shul'gin, V. F.; Meshkova, S. B.

    2015-03-01

    Spectral properties of binuclear zinc complexes in chloroform solutions and polyvinylcarbazole (PVC) films are investigated. It is demonstrated that incorporation of a halogen atom (chlorine or bromine) in a ligand benzene ring leads to a small shift of the spectrum toward the red region and a reduction of the fluorescence quantum yield. The fluorescence and phosphorescence spectra at T = 77K are investigated. The fluorescence undergoes a blue shift of about 30 nm and multiply increases in the intensity, and the phosphorescence is observed at 540-580 nm. The phosphorescence lifetime is estimated. The electroluminescent properties of metal complexes in structures with thermal vacuum spin coating of complexes and in PVC films are investigated.

  2. [Decolorization of reactive blue P-3R with microsphere-supported binuclear Manganese complex as a novel heterogeneous CWPO catalyst].

    Science.gov (United States)

    Song, Min; Zhang, Lin-Ping; Zhong, Yi; Xu, Hong; Mao, Zhi-Ping

    2015-03-01

    Binuclear manganese complex (MnL), with high catalytic activity, was encapsulated into ethyl cellulose microspheres via a microencapsulation technique. The characterization of the catalyst through ICP, UV-VIS, SEM and TEM revealed that MnL was well distributed within the ethyl cellulose matrix. The results of UV-VIS confirmed the structural integrity of MnL after the encapsulation process. The MnL loaded microspheres exhibited an excellent catalytic property in the oxidative decolorization of Reactive Blue P-3R, which was used to simulate the dyestuff wastewater. The dye solution was completely decolorized under the catalyzing action of these microspheres. What's more, these MnL loaded microspheres could be reused for at least 4 times and the decolorization degree of Reactive Blue P-3R was maintained above 70%. The results demonstrated the potential application of the microsphere-supported MnL as a novel heterogeneous CWPO catalyst for the decolorization of wastewater containing dyestuff.

  3. Synthesis and Crystal Structure of Binuclear and Pentanuclear Nickel(II Complexes Containing 4-(salicylaldiminatoantipyrine Schiff base

    Directory of Open Access Journals (Sweden)

    Mohamed N. EL-Kaheli

    2015-11-01

    Full Text Available The new title binuclear Ni (II compound  (1 and the novel pentanuclear Ni (II cluster {[   } (2 are formed from the reaction of an asymmetric Schiff base ligand L (L = 4-(salicylaldiminatoantipyrine with Ni .4  in the former or Ni(ClO42.6H2O in presence of malonate in the later.  Complex (1 consists of ( ]+ cation and one uncoordinated tetraphenylborate anion.  The cation adopts a distorted octahedral arrangement around each metal center.  In the binuclear unit both Ni(II ions are linked through two phenolate (µ2-O oxygen atoms of L, and two oxygen atoms of a  bridging carboxylate group. Each Ni (II coordinates to four oxygen atoms at the basal plane, two oxygen atoms from two bridging phenolate groups, one from pyrazolone ring and the last of an aqua molecule, and at the axial positions to a bridging carboxylate-O atom and an azomethine nitrogen atom.  In the pentanuclear cluster (2 consisting of [ ]+2 cation and two tetraphenylborate anions, the core of the cation is assembled by four [Ni( ] units, linked to the central Ni-ion by two bridging water molecules. The resulting coordination sphere for the external symmetry related nickel ions is a pseudo octahedron.  The central Ni-atom unusually adopts dodecahedron geometry through its coordination to eight bridging water molecules. In complex (1 each Ni-atom is coordinated to one tridentate L ligand and in complex (2 each [Ni ( ] unit is coordinated to two bidentate L ligands.  Inter-and intramolecular hydrogen bonds are present in both crystal structures.

  4. Iron load

    Directory of Open Access Journals (Sweden)

    Filippo Cassarà

    2013-03-01

    Full Text Available Recent research addressed the main role of hepcidin in the regulation of iron metabolism. However, while this mechanism could be relevant in causing iron load in Thalassemia Intermedia and Sickle-Cell Anemia, its role in Thalassemia Major (TM is marginal. This is mainly due to the high impact of transfusional requirement into the severe increase of body iron. Moreover, the damage of iron load may be worsened by infections, as HCV hepatitis, or liver and endocrinological damage. One of the most relevant associations was found between splenectomy and increase of risk for mortality due,probably, to more severe iron load. These issues suggest as morbidity and mortality of this group of patients they do not depend only by our ability in controlling heart damage but even in preventing or treating particular infections and complications. This finding is supported by the impairment of survival curves in patients with complications different from heart damage. However, because, during recent years different direct and indirect methods to detect iron overload in patients affected by secondary hemochromatosis have been implemented, our ability to maintain under control iron load is significantly improved. Anyway, the future in iron load management remains to be able to have an iron load map of our body for targeting chelation and other medical treatment according to the single organ damage.

  5. Expression of iron-related proteins in the duodenum is up-regulated in patients with chronic inflammatory disorders

    Directory of Open Access Journals (Sweden)

    Molly Jacob

    2015-01-01

    Full Text Available Mechanisms responsible for derangements in iron homeostasis in chronic inflammatory conditions are not entirely clear. The aim of this study was to test the hypothesis that inflammation affects expression of iron-related proteins in the duodenum and monocytes in patients with chronic inflammatory disorders, thus contributing to dysregulated iron homeostasis. Duodenal mucosal samples and peripheral blood monocytes obtained from patients with chronic inflammatory disorders, viz. ulcerative colitis (UC, Crohn’s disease (CD and rheumatoid arthritis (RA, were used for gene and protein expression studies. Haemoglobin levels were significantly lower and serum C-reactive protein (CRP levels significantly higher in those in the disease groups. Gene expression of several iron-related proteins in the duodenum was significantly up-regulated in patients with UC and CD. In those with UC, it was found that protein expression of divalent metal transporter (DMT1 and ferroportin, which are involved in absorption of dietary non-heme iron, was also significantly higher in the duodenal mucosa. Gene expression of the duodenal proteins of interest correlated positively with one another and negatively with haemoglobin. Gene expression of iron-related proteins in monocytes was studied in patients with UC and found to be unaffected. In a separate group of patients with UC, serum hepcidin levels were found to be significantly lower than in control subjects. In conclusion, expression of iron related proteins was up-regulated in the duodenum of patients with chronic inflammatory conditions in this study. The effects appeared to be secondary to anemia and the consequent erythropoietic drive.

  6. Iron refractory iron deficiency anemia

    OpenAIRE

    De Falco, Luigia; Sanchez, Mayka; Silvestri, Laura; Kannengiesser, Caroline; Muckenthaler, Martina U; Iolascon, Achille; Gouya, Laurent; Camaschella, Clara; Beaumont, Carole

    2013-01-01

    Iron refractory iron deficiency anemia is a hereditary recessive anemia due to a defect in the TMPRSS6 gene encoding Matriptase-2. This protein is a transmembrane serine protease that plays an essential role in down-regulating hepcidin, the key regulator of iron homeostasis. Hallmarks of this disease are microcytic hypochromic anemia, low transferrin saturation and normal/high serum hepcidin values. The anemia appears in the post-natal period, although in some cases it is only diagnosed in ad...

  7. Bipyridine, an iron chelator, does not lessen intracerebral iron-induced damage or improve outcome after intracerebral hemorrhagic stroke in rats.

    Science.gov (United States)

    Caliaperumal, Jayalakshmi; Wowk, Shannon; Jones, Sarah; Ma, Yonglie; Colbourne, Frederick

    2013-12-01

    Iron chelators, such as the intracellular ferrous chelator 2,2'-bipyridine, are a potential means of ameliorating iron-induced injury after intracerebral hemorrhage (ICH). We evaluated bipyridine against the collagenase and whole-blood ICH models and a simplified model of iron-induced damage involving a striatal injection of FeCl2 in adult rats. First, we assessed whether bipyridine (25 mg/kg beginning 12 h post-ICH and every 12 h for 3 days) would attenuate non-heme iron levels in the brain and lessen behavioral impairments (neurological deficit scale, corner turn test, and horizontal ladder) 7 days after collagenase-induced ICH. Second, we evaluated bipyridine (20 mg/kg beginning 6 h post-ICH and then every 24 h) on edema 3 days after collagenase infusion. Body temperature was continually recorded in a subset of these rats beginning 24 h prior to ICH until euthanasia. Third, bipyridine was administered (as per experiment 2) after whole-blood infusion to examine tissue loss, neuronal degeneration, and behavioral impairments at 7 days post-stroke, as well as body temperature for 3 days post-stroke. Finally, we evaluated whether bipyridine (25 mg/kg given 2 h prior to surgery and then every 12 h for 3 days) lessens tissue loss, neuronal death, and behavioral deficits after striatal FeCl2 injection. Bipyridine caused a significant hypothermic effect (maximum drop to 34.6 °C for 2-5 h after each injection) in both ICH models; however, in all experiments bipyridine-treated rats were indistinguishable from vehicle controls on all other measures (e.g., tissue loss, behavioral impairments, etc.). These results do not support the use of bipyridine against ICH.

  8. Cast irons

    CERN Document Server

    1996-01-01

    Cast iron offers the design engineer a low-cost, high-strength material that can be easily melted and poured into a wide variety of useful, and sometimes complex, shapes. This latest handbook from ASM covers the entire spectrum of one of the most widely used and versatile of all engineered materials. The reader will find the basic, but vital, information on metallurgy, solidification characteristics, and properties. Extensive reviews are presented on the low-alloy gray, ductile, compacted graphite, and malleable irons. New and expanded material has been added covering high-alloy white irons used for abrasion resistance and high-alloy graphitic irons for heat and corrosion resistance. Also discussed are melting furnaces and foundry practices such as melting, inoculation, alloying, pouring, gating and rising, and molding. Heat treating practices including stress relieving, annealing, normalizing, hardening and tempering, autempering (of ductile irons), and surface-hardening treatments are covered, too. ASM Spec...

  9. Binuclear Schiff Base Complexes of m-Xylylenebis(2-(1,3-Propanedi (2-Pyridinealdmine))) and M-Xylylenebis(2-(1,3-Propanedi(2-Pyrrolealdmine))).

    Science.gov (United States)

    1983-11-04

    H;-13 50 I LEAR SCHIFF BASE COMPLEXES OF / M-XYLYLENEBIS(2-(IiC-PROPRNEOI (2-PYRID. (U) ROCHESTER UNIV NY DEPT OF CHEMIISTRY B C WHITMORE ET AL S...1963-A %4. •N V OFFICE OF NAVAL RESEARCH Contract NOO014-83-K-0154 Task No. NR 634-742 TECHNICAL REPORT NO. 2 Binuclear Schiff Base Complexes of m

  10. Nano optical sensor binuclear Pt-2-pyrazinecarboxylic acid -bipyridine for enhancement of the efficiency of 3-nitrotyrosine biomarker for early diagnosis of liver cirrhosis with minimal hepatic encephalopathy.

    Science.gov (United States)

    Attia, M S; Al-Radadi, Najlaa S

    2016-12-15

    A new, precise, and very selective method for increasing the impact and assessment of 3-nitrotyrosine (3-Nty) as a biomarker for early diagnosis of liver cirrhosis with minimal hepatic encephalopathy (MHE) disease was developed. The method depends on the formation of the ion pair associate between 3-nitrotyrosine and the optical sensor binuclear Pt-2-pyrazinecarboxylic acid (pca)-Bipyridine (bpy) complex doped in sol-gel matrix in buffer solution of pH 7.3. The binuclear Pt (pca)(bpy) has +II net charge which is very selective and sensitive for [3-Nty](-2) at pH 7.3 in serum sample of liver cirrhosis with MHE diseases. 3-nitrotyrosine (3-Nty) quenches the luminescence intensity of the nano optical sensor binuclear Pt(pca) (bpy) at 528nm after excitation at 370nm, pH 7.3. The remarkable quenching of the luminescence intensity at 528nm of nano binuclear Pt(pca) (bpy) doped in sol-gel matrix by various concentrations of the 3-Nty was successfully used as an optical sensor for the assessment of 3-Nty in different serum samples of (MHE) in patients with liver cirrhosis. The calibration plot was achieved over the concentration range 1.85×10(-5) - 7.95×10(-10)molL(-1) 3-Nty with a correlation coefficient of (0.999) and a detection limit of (4.7×10(-10)molL(-1)). The method increases the sensitivity (93.75%) and specificity (96.45%) of 3-Nty as a biomarker for early diagnosis of liver cirrhosis with MHE in patients.

  11. Synthesis and characterization of bioactive binuclear transition metal complexes of Schiff base ligand derived from 4-amino-pyrimidine-2-one, diacetyl and glycine

    Directory of Open Access Journals (Sweden)

    Srivastava Abhay Nanda

    2014-01-01

    Full Text Available A series of novel binuclear transition metal complexes was synthesized by reaction of a Schiff base ligand (1-Methyl-2-(2-oxo-1,2-dihydro-pyrimidin-4-ylimino-propylideneamino-acetic acid (LaH derived from 4-amino-pyrimidine-2-one, diacetyl, glycine and corresponding chloride salt of Cu(II, Ni(II, Co(II and Zn(II metals in 1:1 (metal : ligand molar ratio. The compounds were characterized by elemental analyses, molar conductance measurement, magnetic moment measurement and various spectral studies viz. IR, UV-visible, 1H-NMR, 13C-NMR, EPR and ESI-MS. Molar conductance measurement data revealed non-electrolytic nature of metal complexes. Electronic absorption spectral data, electronic paramagnetic resonance parameters and magnetic moment values revealed an octahedral geometry for binuclear metal complexes. Cyclic voltammetric study of Ni(II complex shows a couple of one electron anodic responses near 0.70 V and 1.10 V. In vitro biological activity of Schiff base ligand and binuclear complexes has been checked against bacteria (Staphylococcus aureus, Bacillus subtilis, Escherichia coli and Salmonella typhi and fungi (Candida albicans and Candida parapsilosis to assess their antibacterial and antifungal properties.

  12. Mono- and binuclear copper(I) complexes of thionucleotide analogues and their catalytic activity on the synthesis of dihydrofurans.

    Science.gov (United States)

    Charalampou, D C; Kourkoumelis, N; Karanestora, S; Hadjiarapoglou, L P; Dokorou, V; Skoulika, S; Owczarzak, A; Kubicki, M; Hadjikakou, S K

    2014-08-18

    The reaction of copper(I) halides with 2-thiouracil (TUC), 6-methyl-2-thiouacil (MTUC), and 4-methyl-2-mercaptopyrimidine (MPMTH) in the presence of triphenylphosphine (tpp) in a 1:1:2 molar ratio results in a mixed-ligand copper(I) complex with the formulas [Cu2(tpp)4(TUC)Cl] (1), [Cu2(tpp)4(MTUC)Cl] (2), [Cu(tpp)2(MPMTH)Cl]·(1)/2CH3OH (3), [Cu(tpp)2(MTUC)Br] (4), and [Cu(tpp)2(MTUC)I]·(1)/2CH3CN (5). The complexes have been characterized by FT-IR, (1)H NMR, and UV-vis spectroscopic techniques and single-crystal X-ray crystallography. Complexes 1 and 2 are binuclear copper(I) complexes. Two phosphorus atoms from tpp ligands are coordinated to the copper(I) ions, forming two units that are linked to each other by a deprotonated TUC or MTUC chelating ligand through a sulfur bridge. A linear Cu-S-Cu moiety is formed. The tetrahedral geometry around the metal centers is completed by the nitrogen-donor atom from the TUC or MTUC ligand for the one unit, while for the other one, it is completed by the chloride anion. Two phosphorus atoms from two tpp ligands, one sulfur atom from MPMTH or MTUC ligand, and one halide anion (Cl, Br, and I) form a tetrahedron around the copper ion in 3-5 and two polymorphic forms of 4 (4a and 4b). In all of the complexes, either mono- or binuclear intramolecular O-H···X hydrogen bonds enhance the stability of the structures. On the other hand, in almost all cases of mononuclear complexes (with the exception of a symmetry-independent molecule in 4a), intermolecular NH···O hydrogen-bonding interactions lead to dimerization. Complexes 1-5 were studied for their catalytic activity for the intermolecular cycloaddition of iodonium ylides toward dihydrofuran formation by HPLC, (1)H NMR, and LC-HRMS spectroscopic techniques. The results show that the geometry and halogen and ligand types have a strong effect on the catalytic properties of the complexes. The highest yield of dihydrofurans was obtained when "linear" complexes 1 and 2 were

  13. Syntheses and Crystal Structures of Mono- and Binuclear Copper( Ⅱ ) Mixed-ligand Complexes Involving Schiff Base

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The mononuclear copper(Ⅱ) complex [Cu(L)(2-AP)] 1 and binuclear copper(Ⅱ)complex [Cu(L)(py)]2 2 (L = C1oH1 1O5NS, taurine o-vanillin, py = prydine, 2-AP = 2-aminopyridine)with mixed ligand have been synthesized and characterized by X-ray diffraction method. Crystal data for 1: orthorhombic, space group Pbca with a = 11.921(4), b = 15.816(6), c = 17.076(6) (A), V=3219.7(19) (A)3, C15H17CuN3O5S, Z = 8, Mr = 414.92, Dc = 1.712 g/cm3,μ(MoKα) = 1.520 mm-1,F(000) = 1704, the final R = 0.0300 and wR = 0.0705 for 2840 observed reflections with I > 2σ(I);and crystal data for 2: monoclinic, space group P21/c with a = 7.929(3), b = 17.038(5), c = 11.734(4)(A), β = 98.162(6)°, V = 1569.1 (9) (A)3, C15H16CuN2O5S, Z = 4, Mr = 399.90, Dc = 1.693 g/cm3, F(000)= 820,μ(MoKα) = 1.554 mm-1, the final R = 0.0351 and wR = 0.0848 for 2767 observed reflections (I > 2o(I)). The molecular structure of complex 1 consists of one tetra-coordinated Cu(Ⅱ) atom generating a slightly distorted square plane, and a one-dimensional chain structure is formed by intermolecular hydrogen bonds. Complex 2 consists of a diphenolic hydroxyl O-bridged binuclear copper(Ⅱ) structure. The crystal structures of complexes 1 and 2 reveal that the coordinate copper centers are bound to both nitrogen and oxygen atom donors. The usual N,O-trans arrangement of ligands is observed in both cases.

  14. DNA Binding and Cleavage Activity of Binuclear Metal Complexes with Benzil-α-Monoxime Thiosemicarbzone

    Directory of Open Access Journals (Sweden)

    M. S. Surendra Babu

    2011-01-01

    Full Text Available Transition metal complexes of copper(II, nickel(II, cobalt(II and iron(II with benzil-α-monoxime thiosemicarbazone (BMOT have been synthesized and characterized by molar conductance, magnetic moments, IR, electronic and ESR spectroscopy. Electrochemical behaviors of these complexes were investigated by cyclic voltammetric studies. The nuclease activity of these complexes has been investigated on double-stranded pBR322 circular plasmid DNA by using the gel electrophoresis experiments in presence and absence of oxidant (H2O2. In the absence of oxidant DNA cleavage by hydrolytically was observed a less discernable, whereas in presence of oxidant (H2O2 all complexes showed increased nuclease activity.

  15. METABOLISM OF IRON STORES

    OpenAIRE

    Saito, Hiroshi

    2014-01-01

    ABSTRACT Remarkable progress was recently achieved in the studies on molecular regulators of iron metabolism. Among the main regulators, storage iron, iron absorption, erythropoiesis and hepcidin interact in keeping iron homeostasis. Diseases with gene-mutations resulting in iron overload, iron deficiency, and local iron deposition have been introduced in relation to the regulators of storage iron metabolism. On the other hand, the research on storage iron metabolism has not advanced since th...

  16. Health effects of different dietary iron intakes: a systematic literature review for the 5th Nordic Nutrition Recommendations

    Directory of Open Access Journals (Sweden)

    Magnus Domellöf

    2013-07-01

    ID and IDA in pregnant women can be effectively prevented by iron supplementation at a dose of 40 mg/day from week 18–20 of gestation. There is probable evidence that a high intake of heme iron, but not total dietary, non-heme or supplemental iron, is associated with increased risk of type 2 diabetes (T2D and gestational diabetes. Conclusions : Overall, the evidence does not support a change of the iron intakes recommended in the NNR 4. However, one could consider adding recommendations for infants below 6 months of age, low birth weight infants and pregnant women.

  17. Iron Dextran Injection

    Science.gov (United States)

    ... allergic to iron dextran injection; any other iron injections such as ferric carboxymaltose (Injectafer), ferumoxytol (Feraheme), iron sucrose (Venofer), or sodium ferric gluconate (Ferrlecit);any other ...

  18. Synthesis, characterization and spectrochemical studies on a few binuclear -oxo molybdenum(V) complexes of pyrimidine derived Schiff base ligands

    Indian Academy of Sciences (India)

    Samik Gupta; Somnath Roy; Tarak Nath Mandal; Kinsuk Das; Sangita Ray; Ray J Butcher; Susanta Kumar Kar

    2010-03-01

    Ten new binuclear singly oxo-bridged molybdenum complexes (complexes 1-10) were prepared using five pyrimidine derived Schiff base ligands and two Mo(V) precursors (NH4)2MoOCl5 and (NH4)2MoOBr5. The ligands are prepared by the condensation of 4,6-dimethyl 2-hydrazino pyrimidine with salicylaldehyde (for HL1), -hydroxy acetophenone (for HL2) and substituted salicylaldehydes (for HL3, HL4 and HL5) respectively. These ligands are already reported as good donors for Mo(VI) state. The -oxo Mo(V) complexes reported here bears a distorted octahedral geometry around each Mo atom with either N2O2Cl or N2O2Br chromophores. Fine variations in the spectroscopic behaviour of the complexes are observed in accordance with the varying electron donating properties of the ligands. All the complexes are unstable in solution and X-ray quality crystal of complex 1 could be isolated. All the complexes are characterized by IR and UV-Vis spectra.

  19. Synthesis and Antibacterial Activities of Sulfur-Containing Bissalicylaldehyde Schiff Base and Binuclear Nickel(II Nanorod Complex

    Directory of Open Access Journals (Sweden)

    Xiao-Lan Yang

    2013-01-01

    Full Text Available Nickel(II acetate tetrahydrate was treated with the ligand CH2(H2sal-sbdt2 in methanol heated at reflux to yield a novel binuclear Ni(II nanorod complex of the formula CH2{Ni(II(sal-sbdt(H2O}2. The ligand of CH2(H2sal-sbdt2 was derived from 5,5′-methylene-bissalicylaldehyde and S-benzyldithiocarbazate. The complex was characterized by elemental analysis, UV-Vis, FT-IR spectra, thermal analysis (TG-DSC, and scanning electron microscopy (SEM. The nickel(II was coordinated by imino nitrogen, thiolato sulfur, and phenolic oxygen from the Schiff base ligand, and oxygen from the coordinated water, respectively. The pyrolysis reactions in the thermal decomposition process of the complex, the experimental, and calculated percentage mass loss were also given. The Ni(II complex belonged to nanocrystalline metal complex, and the average size of the nanorod complex was about 30 nm × 150 nm. The antibacterial activities were screened for the Schiff base ligand and the Ni(II nanorod complex against four bacteria: Staphylococcus aureus, Escherichia coli, Bacillus subtilis, and Staphylococcus epidermidis. Both the ligand of CH2(H2sal-sbdt2 and the Ni(II complex had the most intense antibacterial activities against Escherichia coli.

  20. Synthesis and Crystal Structure of Binuclear Silver(Ⅰ)Complex with 2-nitro-(2-pyridylsulfanylmethyl)benzene

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The reaction of 2-nitro-(2-pyridylsulfanylmethyl)benzene L with silver nitrate produces a centrosymmetric binuclear complex bis(2-nitro-(2-pyridylsulfanylmethyl)benzene-N,S)-bis(nitrato-O,O)-disilver(Ⅰ), [AgLNO3]2 1. The crystal is of triclinic, space group P1, with a = 7.383(3), b = 8.340(3), c = 12.003(4) A, a = 95.069(6), β = 93.498(5), γ = 102.734(6)°, C24H2oAg2N6-O10S2, Mr= 832.32, V= 715.6(4) A3, Z = 1, Dc = 1.931 g/cm3, F(000) = 412, μ = 1.581 mm-1, R=0.0351 and wR = 0.0749 Each silver atom is tetrahedrally coordinated by two O atoms from bidentate nitrate, one S atom from a ligand and one N atom from another ligand. Furthermore, AgAg interactions have been observed in the complex.

  1. Visible Light Absorption of Binuclear TiOCoII Charge-Transfer UnitAssembled in Mesoporous Silica

    Energy Technology Data Exchange (ETDEWEB)

    Han, Hongxian; Frei, Heinz

    2007-01-30

    Grafting of CoII(NCCH3)2Cl2 onto mesoporous Ti-MCM-41 silicain acetonitrile solution affords binuclear Ti-O-CoII sites on the poresurface under complete replacement of the precursor ligands byinteractions with anchored Ti centers and the silica surface. The CoIIligand field spectrum signals that the Co centers are anchored on thepore surface in tetrahedral coordination. FT-infrared action spectroscopyusing ammonia gas adsorption reveals Co-O-Si bond modes at 831 and 762cm-1. No Co oxide clusters are observed in the as-synthesized material.The bimetallic moieties feature an absorption extending from the UV intothe visible to about 600 nm which is attributed to the TiIV-O-CoII?3TiIII-O-CoIII metal-to-metal charge-transfer (MMCT) transition. Thechromophore is absent in MCM-41 containing Ti and Co centers isolatedfrom each other; this material was synthesized by grafting CoII onto aTi-MCM-41 sample with the Ti centers protected by a cyclopentadienylligand. The result indicates that the appearance of the charge-transferabsorption requires that the metal centers are linked by an oxo bridge,which is additionally supported by XANES spectroscopy. The MMCTchromophore of Ti-O-CoII units has sufficient oxidation power to serve asvisible light electron pump for driving multi-electron transfer catalystsof demanding uphill reactions such as water oxidation.

  2. Exogenous bridge and tautomer effects on magnetic interaction of binuclear copper(II) complexes of μ-phenolato Schiff bases

    Institute of Scientific and Technical Information of China (English)

    程鹏; 廖代正; 阎世平; 姜宗慧; 王耕霖; 王磊光; 劳学军; 姚心侃; 王宏根; 王国雄

    1996-01-01

    Four enol-form binuclear copper complexes with different exogenous bridges, [Cu2(L)(μ-Cl)] (1), [Cu(L)(μ-N3)]· DMF (2), [Cu2(L)(μ-OCH3)] (3) and [Cu2(L)(μ-C3H3N2)]· 1/2C2H5OH (4), where L is the trivalence anion of binucleating ligand 2,6-diformyl-4-methylphenol di(tenzoylhydrazone), have been synthesized and characterized. Crystal data for complex (3) are as follows: space group P1- , a=0.8294(1), 6=0.9333(3), c= 1.473 6(6) nm, α=79.51(3)°, β=80.93(2)°,γ=81.32(2)°, Z=1. The magnetic measurements indicated that the effect of exogenous bridging ligands on magnetic interaction is corresponding to that in spectrochemical series. The effect of enol- and keto-form tautomer on magnetic interaction was explained from the point of view of structural factors and electron effects by using molecular mechanks and quantum chemistry calculations.

  3. Synthesis and Characterization of an Unexpected Asymmetric Binuclear Copper(Ⅰ) Complex Containing 4-Vinyl-pyridine

    Institute of Scientific and Technical Information of China (English)

    JIANG, Kai(蒋凯); ZHAO, Dong(赵东); GUO, Li-Bing(郭利兵); ZHANG, Chuan-Jian(张传建); YANG, Rui-Na(杨瑞娜)

    2004-01-01

    The asymmetric binuclear copper(Ⅰ) complex [Cu2(dppm)2(C7H7N)(μ-HCOO)](NO3) (dppm=Ph2PCH2PPh2, C7H7N=4-vinyl-pyridine) has been prepared and characterized by physicochemical and spectroscopic methods. The complex is photoluminescent at room temperature. It crystallizes in triclinic system, space group P-1 with a= 1.2719(3) nm, b= 1.8637(4) nm, c= 1.1656(2) nm, α=97.16(3)°, β= 104.94(3)°, γ=89.39(3)°, V=2.648.1(9) nm3, Dc= 1.390 gbcm-3, Z=2, μ=0.974 mm-1, R=0.0483 for 5716 independently observed reflections with I>2σ(I).The structure consists of [Cu2(dppm)2(C7H7N)(μ-HCOO)]+cations and nitrate anions. The copper atoms show different coordination modes: Cu(1) displays a distorted trigonal and Cu(2) a tetrahedred geometry.

  4. X-ray and DFT studies of a mono- and binuclear copper(II) ionic compound containing a Schiff base.

    Science.gov (United States)

    Langer, Vratislav; Mach, Pavol; Gyepesová, Dalma; Andrezálová, Lucia; Kohútová, Mária

    2012-11-01

    In the structure of trans-bis(ethanol-κO)tetrakis(1H-imidazole-κN(3))copper(II) bis[μ-N-(2-oxidobenzylidene)-D,L-glutamato]-κ(4)O(1),N,O(2'):O(2');κ(4)O(2'):O(1),N,O(2')-bis[(1H-imidazole-κN(3))cuprate(II)], [Cu(C(3)H(4)N(2))(4)(C(2)H(6)O)(2)][Cu(2)(C(15)H(14)N(3)O(5))(2)], both ions are located on centres of inversion. The cation is mononuclear, showing a distorted octahedral coordination, while the anion is a binuclear centrosymmetric dimer with a square-pyramidal copper(II) coordination. An extensive three-dimensional hydrogen-bonding network is formed between the ions. According to B3LYP/6-31G* calculations, the two equivalent components of the anion are in doublet states (spin density located mostly on Cu(II) ions) and are coupled as a triplet, with only marginal preference over an open-shell singlet.

  5. Iron Sucrose Injection

    Science.gov (United States)

    Iron sucrose injection is used treat iron-deficiency anemia (a lower than normal number of red blood cells due ... and may cause the kidneys to stop working). Iron sucrose injection is in a class of medications called iron ...

  6. Iron deficiency

    DEFF Research Database (Denmark)

    Schou, Morten; Bosselmann, Helle; Gaborit, Freja

    2015-01-01

    BACKGROUND: Both iron deficiency (ID) and cardiovascular biomarkers are associated with a poor outcome in heart failure (HF). The relationship between different cardiovascular biomarkers and ID is unknown, and the true prevalence of ID in an outpatient HF clinic is probably overlooked. OBJECTIVES.......043). CONCLUSION: ID is frequent in an outpatient HF clinic. ID is not associated with cardiovascular biomarkers after adjustment for traditional confounders. Inflammation, but not neurohormonal activation is associated with ID in systolic HF. Further studies are needed to understand iron metabolism in elderly HF...

  7. Iron Polymerization and Arsenic Removal During In-Situ Iron Electrocoagulation in Synthetic Bangladeshi Groundwater

    Science.gov (United States)

    van Genuchten, C. M.; Pena, J.; Addy, S.; Gadgil, A.

    2010-12-01

    Millions of people worldwide are exposed to arsenic-contamination in groundwater drinking supplies. The majority of affected people live in rural Bangladesh. Electrocoagulation (EC) using iron electrodes is a promising arsenic removal strategy that is based on the generation of iron precipitates with a high affinity for arsenic through the electrochemical dissolution of a sacrificial iron anode. Many studies of iron hydrolysis in the presence of co-occurring ions in groundwater such as PO43-, SiO44-, and AsO43- suggest that these ions influence the polymerization and formation of iron oxide phases. However, the combined impact of these ions on precipitates generated by EC is not well understood. X-ray absorption spectroscopy (XAS) was used to examine EC precipitates generated in synthetic Bangladeshi groundwater (SBGW). The iron oxide structure and arsenic binding geometry were investigated as a function of EC operating conditions. As and Fe k-edge spectra were similar between samples regardless of the large range of current density (0.02, 1.1, 5.0, 100 mA/cm2) used during sample generation. This result suggests that current density does not play a large role in the formation EC precipitates in SBGW. Shell-by-shell fits of Fe K-edge data revealed the presence of a single Fe-Fe interatomic distance at approximately 3.06 Å. The absence of longer ranged Fe-Fe correlations suggests that EC precipitates consist of nano-scale chains (polymers) of FeO6 octahedra sharing equatorial edges. Shell-by-shell fits of As K-edge spectra show arsenic bound in primarily bidentate, binuclear corner sharing complexes. In this coordination geometry, arsenic prevents the formation of FeO6 corner-sharing linkages, which are necessary for 3-dimensional crystal growth. The individual and combined effects of other anions, such as PO43- and SiO44- present in SBGW are currently being investigated to determine the role of these ions in stunting crystal growth. The results provided by this

  8. Functional diversification of the RING finger and other binuclear treble clef domains in prokaryotes and the early evolution of the ubiquitin system.

    Science.gov (United States)

    Burroughs, A Maxwell; Iyer, Lakshminarayan M; Aravind, L

    2011-07-01

    Recent studies point to a diverse assemblage of prokaryotic cognates of the eukaryotic ubiquitin (Ub) system. These systems span an entire spectrum, ranging from those catalyzing cofactor and amino acid biosynthesis, with only adenylating E1-like enzymes and ubiquitin-like proteins (Ubls), to those that are closer to eukaryotic systems by virtue of possessing E2 enzymes. Until recently E3 enzymes were unknown in such prokaryotic systems. Using contextual information from comparative genomics, we uncover a diverse group of RING finger E3s in prokaryotes that are likely to function with E1s, E2s, JAB domain peptidases and Ubls. These E1s, E2s and RING fingers suggest that features hitherto believed to be unique to eukaryotic versions of these proteins emerged progressively in such prokaryotic systems. These include the specific configuration of residues associated with oxyanion-hole formation in E2s and the C-terminal UFD in the E1 enzyme, which presents the E2 to its active site. Our study suggests for the first time that YukD-like Ubls might be conjugated by some of these systems in a manner similar to eukaryotic Ubls. We also show that prokaryotic RING fingers possess considerable functional diversity and that not all of them are involved in Ub-related functions. In eukaryotes, other than RING fingers, a number of distinct binuclear (chelating two Zn atoms) and mononuclear (chelating one zinc atom) treble clef domains are involved in Ub-related functions. Through detailed structural analysis we delineated the higher order relationships and interaction modes of binuclear treble clef domains. This indicated that the FYVE domain acquired the binuclear state independently of the other binuclear forms and that different treble clef domains have convergently acquired Ub-related functions independently of the RING finger. Among these, we uncover evidence for notable prokaryotic radiations of the ZF-UBP, B-box, AN1 and LIM clades of treble clef domains and present

  9. Synthesis, spectroscopic and biological activities studies of acyclic and macrocyclic mono and binuclear metal complexes containing a hard-soft Schiff base

    Science.gov (United States)

    Abou-Hussein, Azza A. A.; Linert, Wolfgang

    Mono- and bi-nuclear acyclic and macrocyclic complexes with hard-soft Schiff base, H2L, ligand derived from the reaction of 4,6-diacetylresorcinol and thiocabohydrazide, in the molar ratio 1:2 have been prepared. The H2L ligand reacts with Co(II), Ni(II), Cu(II), Zn(II), Mn(II) and UO2(VI) nitrates, VO(IV) sulfate and Ru(III) chloride to get acyclic binuclear complexes except for VO(IV) and Ru(III) which gave acyclic mono-nuclear complexes. Reaction of the acyclic mono-nuclear VO(IV) and Ru(III) complexes with 4,6-diacetylresorcinol afforded the corresponding macrocyclic mono-nuclear VO(IV) and Ru(IIII) complexes. Template reactions of the 4,6-diacetylresorcinol and thiocarbohydrazide with either VO(IV) or Ru(III) salts afforded the macrocyclic binuclear VO(IV) and Ru(III) complexes. The Schiff base, H2L, ligand acts as dibasic with two NSO-tridentate sites and can coordinate with two metal ions to form binuclear complexes after the deprotonation of the hydrogen atoms of the phenolic groups in all the complexes, except in the case of the acyclic mononuclear Ru(III) and VO(IV) complexes, where the Schiff base behaves as neutral tetradentate chelate with N2S2 donor atoms. The ligands and the metal complexes were characterized by elemental analysis, IR, UV-vis 1H-NMR, thermal gravimetric analysis (TGA) and ESR, as well as the measurements of conductivity and magnetic moments at room temperature. Electronic spectra and magnetic moments of the complexes indicate the geometries of the metal centers are either tetrahedral, square planar or octahedral. Kinetic and thermodynamic parameters were calculated using Coats-Redfern equation, for the different thermal decomposition steps of the complexes. The ligands and the metal complexes were screened for their antimicrobial activity against Staphylococcus aureus as Gram-positive bacteria, and Pseudomonas fluorescens as Gram-negative bacteria in addition to Fusarium oxysporum fungus. Most of the complexes exhibit mild

  10. Iron bioavailability from commercially available iron supplements

    OpenAIRE

    2015-01-01

    Purpose Iron deficiency anaemia (IDA) is a global public health problem. Treatment with the standard of care ferrous iron salts may be poorly tolerated, leading to non-compliance and ineffective correction of IDA. Employing supplements with higher bioavailability might permit lower doses of iron to be used with fewer side effects, thus improving treatment efficacy. Here, we compared the iron bioavailability of ferrous sulphate tablets with alternative commercial iron products, including th...

  11. Transdermal iron replenishment therapy.

    Science.gov (United States)

    Modepalli, Naresh; Shivakumar, H N; Kanni, K L Paranjothy; Murthy, S Narasimha

    2015-01-01

    Iron deficiency anemia is one of the major nutritional deficiency disorders. Iron deficiency anemia occurs due to decreased absorption of iron from diet, chronic blood loss and other associated diseases. The importance of iron and deleterious effects of iron deficiency anemia are discussed briefly in this review followed by the transdermal approaches to deliver iron. Transdermal delivery of iron would be able to overcome the side effects associated with conventional oral and parenteral iron therapy and improves the patient compliance. During preliminary investigations, ferric pyrophosphate and iron dextran were selected as iron sources for transdermal delivery. Different biophysical techniques were explored to assess their efficiency in delivering iron across the skin, and in vivo studies were carried out using anemic rat model. Transdermal iron delivery is a promising approach that could make a huge positive impact on patients suffering with iron deficiency.

  12. Highly Selective Salicylate Membrane Electrode Based on N,N'-(Aminoethyl)ethylenediamide Bis(2-salicylideneimine) Binuclear Copper(Ⅱ) Complex as Neutral Carrier

    Institute of Scientific and Technical Information of China (English)

    SUN, Ai-Li; CHAI, Ya-Qin; YUAN, Ruo; GUI, Guo-Feng

    2006-01-01

    A new ion selective electrode for salicylate based on N,N'-(aminoethyl)ethylenediamide bis(2-salicylideneimine)binuclear copper(Ⅱ) complex [Cu(Ⅱ)2-AEBS] as an ionophore was developed. The electrode has a linear range from 1.0 × 10-1 to 5.0 × 10-7 mol· L-1 with a near-Nemstian slope of (-55 ± 1) mV/decade and a detection limit of 2.0 ×10-7 mol·L-1 in phosphorate buffer solution of pH 5.0 at 25 ℃. It shows good selectivity for Sal and displays anti-Hofmeister selectivity sequence: Sal- > SCN-> ClO4-> I- > NO2- > Br- > NO3- > Cl- > SO32- > SO42-The proposed sensor based on binuclear copper(Ⅱ)complex has a fast response time of 5-10 s and can be used for at least 2 months without any major deviation. The response mechanism is discussed in view of the alternating current (AC) impedance technique and the UV-vis spectroscopy technique. The effect of the electrode membrane compositions and the experimental conditions were studied. The electrode has been successfully used for the determination of salicylate ion in drug pharmaceutical preparations.

  13. Binuclear and tetranuclear Mn(II) clusters in coordination polymers derived from semirigid tetracarboxylate and N-donor ligands: syntheses, new topology structures and magnetism

    Science.gov (United States)

    Li, Xiao-Ling; Liu, Guang-Zhen; Xin, Ling-Yun; Wang, Li-Ya

    2017-02-01

    Two topologically new Mn(II) coordination polymers, namely {[Mn2(H4ipca)(4,4‧-bpy)1.5(CH3CH2OH)0.5(H2O)1.5]·0.5CH3CH2OH·2.5H2O}n (1) and {Mn4(H4ipca)2(bze)(H2O)4}n (2) were prepared by the solvothermal reactions of Mn(II) acetate with 5-(2',3'-dicarboxylphenoxy)isophthalic acid (H4ipca) in the presence of different N-donor coligands (4,4‧-bpy=4,4‧-bipyridyl and bze=1, 4-bis(1-imidazoly)benzene). The single crystal X-ray diffractions reveal that two complexes display 3D metal-organic frameworks with binuclear and tetranuclear Mn(II) units, respectively. Complex 1 features a (3,4,6)-connected porous framework based on dinuclear Mn(II) unit with the (4.52)2(42.68.83.92)(52.8.92.10) new topology, and complex 2 possesses a (3,8)-connected network based on tetranuclear Mn(II) unit with the (42.6)2(44.614.77.82.9) new topology. Magnetic analyses indicate that both two compounds show weak antiferromagnetic interactions within binuclear and tetranuclear Mn(II) units.

  14. Structural, spectral and biological studies of binuclear tetradentate metal complexes of N 3O Schiff base ligand synthesized from 4,6-diacetylresorcinol and diethylenetriamine

    Science.gov (United States)

    Emara, Adel A. A.

    2010-09-01

    The binuclear Schiff base, H 2L, ligand was synthesized by reaction of 4,6-diacetylresorcinol with diethylenetriamine in the molar ratio 1:2. The coordination behavior of the H 2L towards Cu(II), Ni(II), Co(II), Zn(II), Fe(III), Cr(III), VO(IV) and UO 2(VI) ions has been investigated. The elemental analyses, magnetic moments, thermal studies and IR, electronic, 1H NMR, ESR and mass spectra were used to characterize the isolated ligand and its metal complexes. The ligand acts as dibasic with two N 3O-tetradentate sites and can coordinate with two metal ions to form binuclear complexes. The bonding sites are the nitrogen atoms of the azomethine and amine groups and the oxygen atoms of the phenolic groups. The metal complexes exhibit either square planar, tetrahedral, square pyramid or octahedral structures. The Schiff base ligand and its metal complexes were tested against four pathogenic bacteria ( Staphylococcus aureus and Streptococcus pyogenes) as Gram-positive bacteria, and ( Pseudomonas fluorescens and Pseudomonas phaseolicola) as Gram-negative bacteria and two pathogenic fungi ( Fusarium oxysporum and Aspergillus fumigatus) to assess their antimicrobial properties. Most of the complexes exhibit mild antibacterial and antifungal activities against these organisms.

  15. Mononuclear thiocyanate containing nickel(II) and binuclear azido bridged nickel(II) complexes of N4-coordinate pyrazole based ligand: Syntheses, structures and magnetic properties

    Science.gov (United States)

    Solanki, Ankita; Monfort, Montserrat; Kumar, Sujit Baran

    2013-10-01

    Two mononuclear nickel(II) complexes [NiL1(NCS)2] (1) and [NiL2(NCS)2] (2) and two azido bridged binuclear nickel(II) complexes [Ni(()2()2] (3) and [Ni(()2()2] (4), where L1, L2, L1‧ and L2‧ are N,N-diethyl-N‧,N‧-bis((3,5-dimethyl-1H-pyrazol-1-yl)methyl)ethane-1,2-diamine (L1), N,N-bis((1H-pyrazol-1-yl)methyl)-N‧,N‧-diethylethane-1,2-diamine (L2), N,N-diethyl-N‧-((3,5-dimethyl-1H-pyrazol-1-yl)methyl)ethane-1,2-diamine (L1‧) and N-((1H-pyrazol-1-yl)methyl)-N‧,N‧-diethylethane-1,2-diamine (L2‧) have been synthesized and characterized by microanalyses and physico-chemical methods. Single crystal X-ray diffraction analyses revealed that complexes 1 and 2 are mononuclear NCS- containing Ni(II) complex with octahedral geometry and complexes 3 and 4 are end-on (μ-1,1) azido bridged binuclear Ni(II) complexes with distorted octahedral geometry. Variable temperature magnetic studies of the complexes 3 and 4 display ferromagnetic interaction with J values 19 and 32 cm-1, respectively.

  16. Iron and iron derived radicals

    Energy Technology Data Exchange (ETDEWEB)

    Borg, D.C.; Schaich, K.M.

    1987-04-01

    We have discussed some reactions of iron and iron-derived oxygen radicals that may be important in the production or treatment of tissue injury. Our conclusions challenge, to some extent, the usual lines of thought in this field of research. Insofar as they are born out by subsequent developments, the lessons they teach are two: Think fastexclamation Think smallexclamation In other words, think of the many fast reactions that can rapidly alter the production and fate of highly reactive intermediates, and when considering the impact of competitive reactions on such species, think how they affect the microenvironment (on the molecular scale) ''seen'' by each reactive molecule. 21 refs., 3 figs., 1 tab.

  17. Iron(III) complexes of certain tetradentate phenolate ligands as functional models for catechol dioxygenases

    Indian Academy of Sciences (India)

    Mallayan Palaniandavar; Marappan Velusamy; Ramasamy Mayilmurugan

    2006-11-01

    Catechol 1,2-dioxygenase (CTD) and protocatechuate 3,4-dioxygenase (PCD) are bacterial non-heme iron enzymes, which catalyse the oxidative cleavage of catechols to cis, cis-muconic acids with the incorporation of molecular oxygen via a mechanism involving a high-spin ferric centre. The iron(III) complexes of tripodal phenolate ligands containing N3O and N2O2 donor sets represent the metal binding region of the iron proteins. In our laboratory iron(III) complexes of mono- and bisphenolate ligands have been studied successfully as structural and functional models for the intradiol-cleaving catechol dioxygenase enzymes. The single crystal X-ray crystal structures of four of the complexes have been determined. One of the bis-phenolato complexes contains a FeN2O2Cl chromophore with a novel trigonal bipyramidal coordination geometry. The Fe-O-C bond angle of 136.1° observed for one of the iron(III) complex of a monophenolate ligand is very similar to that in the enzymes. The importance of the nearby sterically demanding coordinated -NMe2 group has been established and implies similar stereochemical constraints from the other ligated amino acid moieties in the 3,4-PCD enzymes, the enzyme activity of which is traced to the difference in the equatorial and axial Fe-O(tyrosinate) bonds (Fe-O-C, 133, 148°). The nature of heterocyclic rings of the ligands and the methyl substituents on them regulate the electronic spectral features, FeIII/FeII redox potentials and catechol cleavage activity of the complexes. Upon interacting with catecholate anions, two catecholate to iron(III) charge transfer bands appear and the low energy band is similar to that of catechol dioxygenase-substrate complex. Four of the complexes catalyze the oxidative cleavage of H2DBC by molecular oxygen to yield intradiol cleavage products. Remarkably, the more basic N-methylimidazole ring in one of the complexes facilitates the rate-determining productreleasing phase of the catalytic reaction. The present

  18. Spectroscopic and biological studies of new binuclear metal complexes of a tridentate ONS hydrazone ligand derived from 4-amino-6-methyl-3-thioxo-3,4-dihydro-1,2,4-triazin-5(2H)-one and 4,6-diacetylresorcinol.

    Science.gov (United States)

    Adly, Omima M I; Emara, Adel A A

    2014-11-11

    The binuclear hydrazone, H2L, ligand derived from 4-amino-6-methyl-3-thioxo-3,4-dihydro-1,2,4-triazin-5(2H)-one and 4,6-diacetylresorcinol, in the molar ratio 2:1, and its copper(II), nickel(II), cobalt(II), zinc(II), cadmium(II), cerium(III), iron(III), oxovanadium(IV) and dioxouranium(VI) complexes have been synthesized. Structures of the ligand and its metal complexes were characterized by elemental analyses, spectral (infrared, electronic, mass, 1H NMR and ESR) data, magnetic susceptibility, molar conductivity measurements and thermal gravimetric analysis (TGA). The ligand acts as dibasic with two ONS tridentate sites. The bonding sites are the azomethine nitrogen, phenolate oxygen and sulfur atoms. The metal complexes exhibit different geometrical arrangements such as square planer, tetrahedral and octahedral. The Coats-Redfern equation was used to calculate the kinetic and thermodynamic parameters for the different thermal decomposition steps of some complexes. The ligand and its metal complexes showed antimicrobial activity towards Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis), Gram-negative bacteria (Salmonella typhimurium and Escherichia coli), yeast (Candida albicans) and fungus (Aspergillus fumigatus). Structural parameters of the ligand and its metal complexes were theoretically computed on the basis of semiempirical PM3 level, and the results were correlated with their experimental data.

  19. Spectroscopic and biological studies of new binuclear metal complexes of a tridentate ONS hydrazone ligand derived from 4-amino-6-methyl-3-thioxo-3,4-dihydro-1,2,4-triazin-5(2H)-one and 4,6-diacetylresorcinol

    Science.gov (United States)

    Adly, Omima M. I.; Emara, Adel A. A.

    2014-11-01

    The binuclear hydrazone, H2L, ligand derived from 4-amino-6-methyl-3-thioxo-3,4-dihydro-1,2,4-triazin-5(2H)-one and 4,6-diacetylresorcinol, in the molar ratio 2:1, and its copper(II), nickel(II), cobalt(II), zinc(II), cadmium(II), cerium(III), iron(III), oxovanadium(IV) and dioxouranium(VI) complexes have been synthesized. Structures of the ligand and its metal complexes were characterized by elemental analyses, spectral (infrared, electronic, mass, 1H NMR and ESR) data, magnetic susceptibility, molar conductivity measurements and thermal gravimetric analysis (TGA). The ligand acts as dibasic with two ONS tridentate sites. The bonding sites are the azomethine nitrogen, phenolate oxygen and sulfur atoms. The metal complexes exhibit different geometrical arrangements such as square planer, tetrahedral and octahedral. The Coats-Redfern equation was used to calculate the kinetic and thermodynamic parameters for the different thermal decomposition steps of some complexes. The ligand and its metal complexes showed antimicrobial activity towards Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis), Gram-negative bacteria (Salmonella typhimurium and Escherichia coli), yeast (Candida albicans) and fungus (Aspergillus fumigatus). Structural parameters of the ligand and its metal complexes were theoretically computed on the basis of semiempirical PM3 level, and the results were correlated with their experimental data.

  20. Iron and stony-iron meteorites

    DEFF Research Database (Denmark)

    Benedix, Gretchen K.; Haack, Henning; McCoy, T. J.

    2014-01-01

    Without iron and stony-iron meteorites, our chances of ever sampling the deep interior of a differentiated planetary object would be next to nil. Although we live on a planet with a very substantial core, we will never be able to sample it. Fortunately, asteroid collisions provide us with a rich...... sampling of the deep interiors of differentiated asteroids. Iron and stony-iron meteorites are fragments of a large number of asteroids that underwent significant geological processing in the early solar system. Parent bodies of iron and some stony-iron meteorites completed a geological evolution similar...

  1. Iron and Your Child

    Science.gov (United States)

    ... extra iron in their diets. People following a vegetarian diet might also need additional iron. What's Iron ... as Whole Milk? About Anemia Minerals What's a Vegetarian? Word! Anemia Anemia Food Labels Vitamins and Minerals ...

  2. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... or an inability to absorb enough iron from food. Overview Iron-deficiency anemia is a common type ... of the condition. Treatments may include dietary changes, medicines, and surgery. Severe iron-deficiency anemia may require ...

  3. Genetics Home Reference: iron-refractory iron deficiency anemia

    Science.gov (United States)

    ... refractory iron deficiency anemia iron-refractory iron deficiency anemia Enable Javascript to view the expand/collapse boxes. ... All Close All Description Iron-refractory iron deficiency anemia is one of many types of anemia , which ...

  4. An iron 13S-lipoxygenase with an α-linolenic acid specific hydroperoxidase activity from Fusarium oxysporum.

    Directory of Open Access Journals (Sweden)

    Florian Brodhun

    Full Text Available Jasmonates constitute a family of lipid-derived signaling molecules that are abundant in higher plants. The biosynthetic pathway leading to plant jasmonates is initiated by 13-lipoxygenase-catalyzed oxygenation of α-linolenic acid into its 13-hydroperoxide derivative. A number of plant pathogenic fungi (e.g. Fusarium oxysporum are also capable of producing jasmonates, however, by a yet unknown biosynthetic pathway. In a search for lipoxygenase in F. oxysporum, a reverse genetic approach was used and one of two from the genome predicted lipoxygenases (FoxLOX was cloned. The enzyme was heterologously expressed in E. coli, purified via affinity chromatography, and its reaction mechanism characterized. FoxLOX was found to be a non-heme iron lipoxygenase, which oxidizes C18-polyunsaturated fatty acids to 13S-hydroperoxy derivatives by an antarafacial reaction mechanism where the bis-allylic hydrogen abstraction is the rate-limiting step. With α-linolenic acid as substrate FoxLOX was found to exhibit a multifunctional activity, because the hydroperoxy derivatives formed are further converted to dihydroxy-, keto-, and epoxy alcohol derivatives.

  5. Iron-refractory iron deficiency anemia.

    Science.gov (United States)

    Yılmaz Keskin, Ebru; Yenicesu, İdil

    2015-03-05

    Iron is essential for life because it is indispensable for several biological reactions, such as oxygen transport, DNA synthesis, and cell proliferation. Over the past few years, our understanding of iron metabolism and its regulation has changed dramatically. New disorders of iron metabolism have emerged, and the role of iron as a cofactor in other disorders has begun to be recognized. The study of genetic conditions such as hemochromatosis and iron-refractory iron deficiency anemia (IRIDA) has provided crucial insights into the molecular mechanisms controlling iron homeostasis. In the future, these advances may be exploited to improve treatment of both genetic and acquired iron disorders. IRIDA is caused by mutations in TMPRSS6, the gene encoding matriptase-2, which downregulates hepcidin expression under conditions of iron deficiency. The typical features of this disorder are hypochromic, microcytic anemia with a very low mean corpuscular volume of erythrocytes, low transferrin saturation, no (or inadequate) response to oral iron, and only a partial response to parenteral iron. In contrast to classic iron deficiency anemia, serum ferritin levels are usually low-normal, and serum or urinary hepcidin levels are inappropriately high for the degree of anemia. Although the number of cases reported thus far in the literature does not exceed 100, this disorder is considered the most common of the "atypical" microcytic anemias. The aim of this review is to share the current knowledge on IRIDA and increase awareness in this field.

  6. Iron-Refractory Iron Deficiency Anemia

    Science.gov (United States)

    Yılmaz Keskin, Ebru; Yenicesu, İdil

    2015-01-01

    Iron is essential for life because it is indispensable for several biological reactions, such as oxygen transport, DNA synthesis, and cell proliferation. Over the past few years, our understanding of iron metabolism and its regulation has changed dramatically. New disorders of iron metabolism have emerged, and the role of iron as a cofactor in other disorders has begun to be recognized. The study of genetic conditions such as hemochromatosis and iron-refractory iron deficiency anemia (IRIDA) has provided crucial insights into the molecular mechanisms controlling iron homeostasis. In the future, these advances may be exploited to improve treatment of both genetic and acquired iron disorders. IRIDA is caused by mutations in TMPRSS6, the gene encoding matriptase-2, which downregulates hepcidin expression under conditions of iron deficiency. The typical features of this disorder are hypochromic, microcytic anemia with a very low mean corpuscular volume of erythrocytes, low transferrin saturation, no (or inadequate) response to oral iron, and only a partial response to parenteral iron. In contrast to classic iron deficiency anemia, serum ferritin levels are usually low-normal, and serum or urinary hepcidin levels are inappropriately high for the degree of anemia. Although the number of cases reported thus far in the literature does not exceed 100, this disorder is considered the most common of the “atypical” microcytic anemias. The aim of this review is to share the current knowledge on IRIDA and increase awareness in this field. PMID:25805669

  7. Iron from Zealandic bog iron ore -

    DEFF Research Database (Denmark)

    Lyngstrøm, Henriette Syrach

    2011-01-01

    og geologiske materiale, metallurgiske analyser og eksperimentel arkæologiske forsøg - konturerne af en jernproduktion med udgangspunkt i den sjællandske myremalm. The frequent application by archaeologists of Werner Christensen’s distribution map for the occurrence of bog iron ore in Denmark (1966...... are sketched of iron production based on bog iron ore from Zealand....

  8. Liver iron transport

    Institute of Scientific and Technical Information of China (English)

    Ross M Graham; Anita CG Chua; Carly E Herbison; John K Olynyk; Debbie Trinder

    2007-01-01

    The liver plays a central role in iron metabolism. It is the major storage site for iron and also expresses a complex range of molecules which are involved in iron transport and regulation of iron homeostasis. An increasing number of genes associated with hepatic iron transport or regulation have been identified. These include transferrin receptors (TFR1 and 2), a ferrireductase (STEAP3), the transporters divalent metal transporter-1 (DMT1) and ferroportin (FPN) as well as the haemochromatosis protein, HFE and haemojuvelin (HJV),which are signalling molecules. Many of these genes also participate in iron regulatory pathways which focus on the hepatic peptide hepcidin. However, we are still only beginning to understand the complex interactions between liver iron transport and iron homeostasis. This review outlines our current knowledge of molecules of iron metabolism and their roles in iron transport and regulation of iron homeostasis.

  9. Native iron

    DEFF Research Database (Denmark)

    Brooks, Charles Kent

    2015-01-01

    System, was reduced. The oxidized outer layers of the Earth have formed by two processes. Firstly, water is decomposed to oxygen and hydrogen by solar radiation in the upper parts of the atmosphere, the light hydrogen diffusing to space, leaving oxygen behind. Secondly, plants, over the course......We live in an oxidized world: oxygen makes up 22 percent of the atmosphere and by reacting with organic matter produces most of our energy, including the energy our bodies use to function: breathe, think, move, etc. It has not always been thus. Originally the Earth, in common with most of the Solar......, hematite, or FeO.Fe2O3, magnetite), with carbon in the form of coke. This is carried out in a blast furnace. Although the Earth's core consists of metallic iron, which may also be present in parts of the mantle, this is inaccessible to us, so we must make our own. In West Greenland, however, some almost...

  10. Synthesis, structure, biochemical, and docking studies of a new dinitrosyl iron complex [Fe2(μ-SC4H3SCH2)2(NO)4

    Science.gov (United States)

    Davidovich, P. B.; Fischer, A. I.; Korchagin, D. V.; Panchuk, V. V.; Shchukarev, A. V.; Garabadzhiu, A. V.; Belyaev, A. N.

    2015-07-01

    A new dinitrosyl iron complex of binuclear structure [Fe2(μ-S-2-methylthiophene)2(NO)4] was first synthesized and structurally characterized by XRD and theoretical methods. Using caspase-3 as an example it was shown that [Fe2(μ-S-2-methylthiophene)2(NO)4] and its analog [Fe2(μ-S-2-methylfurane)2(NO)4] can inhibit the action of active site cysteine proteins; the difference in inhibitory activity was explained by molecular docking studies. Biochemical and in silico studies give grounds that the biological activity of dinitrosyl iron complexes is a μ-SR bridging ligand structure function. Thus the rational design strategy of [Fe2(μ-SR)2(NO)4] complexes can be applied to make NO prodrugs with high affinity to therapeutically significant targets involved in cancer and inflammation.

  11. [Iron-refractory iron deficiency anemia].

    Science.gov (United States)

    Kawabata, Hiroshi

    2016-02-01

    The major causes of iron deficiency anemia (IDA) include iron loss due to bleeding, increased iron requirements, and decreased iron absorption by the intestine. The most common cause of IDA in Japanese women is iron loss during menstruation. Autoimmune atrophic gastritis and Helicobacter pylori infection can also cause IDA by reducing intestinal iron absorption. In addition to these common etiologies, germline mutations of TMPRSS6 can cause iron-refractory IDA (IRIDA). TMPRSS6 encodes matriptase-2, a membrane-bound serine protease primarily expressed in the liver. Functional loss of matriptase-2 due to homozygous mutations results in an increase in the expression of hepcidin, which is the key regulator of systemic iron homeostasis. The serum hepcidin increase in turn leads to a decrease in iron supply from the intestine and macrophages to erythropoietic cells. IRIDA is microcytic and hypochromic, but decreased serum ferritin is not observed as in IDA. IRIDA is refractory to oral iron supplementation, but does respond to intravenous iron supplementation to some extent. Because genetic testing is required for the diagnoses of IRIDA, a considerable number of cases may go undiagnosed and may thus be overlooked.

  12. Serum iron test

    Science.gov (United States)

    Fe+2; Ferric ion; Fe++; Ferrous ion; Iron - serum; Anemia - serum iron; Hemochromatosis - serum iron ... A blood sample is needed. Iron levels are highest in the morning. Your health care provider will likely have you do this test in the morning.

  13. Iron deficiency anemia

    Science.gov (United States)

    Anemia - iron deficiency ... iron from old red blood cells. Iron deficiency anemia develops when your body's iron stores run low. ... You may have no symptoms if the anemia is mild. Most of the time, ... slowly. Symptoms may include: Feeling weak or tired more often ...

  14. Nutritional iron deficiency

    NARCIS (Netherlands)

    Zimmermann, M.B.; Hurrell, R.F.

    2007-01-01

    Iron deficiency is one of the leading risk factors for disability and death worldwide, affecting an estimated 2 billion people. Nutritional iron deficiency arises when physiological requirements cannot be met by iron absorption from diet. Dietary iron bioavailability is low in populations consuming

  15. Iron stress in plants.

    Science.gov (United States)

    Connolly, Erin L; Guerinot, Mary

    2002-07-30

    Although iron is an essential nutrient for plants, its accumulation within cells can be toxic. Plants, therefore, respond to both iron deficiency and iron excess by inducing expression of different gene sets. Here, we review recent advances in the understanding of iron homeostasis in plants gained through functional genomic approaches

  16. Iron stress in plants

    OpenAIRE

    Connolly, Erin L.; Guerinot, Mary Lou

    2002-01-01

    Although iron is an essential nutrient for plants, its accumulation within cells can be toxic. Plants, therefore, respond to both iron deficiency and iron excess by inducing expression of different gene sets. Here, we review recent advances in the understanding of iron homeostasis in plants gained through functional genomic approaches.

  17. Urinary iron excretion test in iron deficiency anemia.

    Directory of Open Access Journals (Sweden)

    Kimura,Ikuro

    1980-02-01

    Full Text Available A urinary iron excretion test was carried out in 22 patients with iron deficiency anemia. The iron excretion index was significantly higher in patients with intractable iron deficiency anemia compared with normal subjects and anemic patients who were responsive to iron therapy. The findings suggest that iron excretion may be a factor that modulates the response of patients to iron therapy.

  18. Synthesis, Characterization, Spectroscopic and Electrochemical Properties of New Mono-and Binuclear Copper(Ⅰ) Complexes with Substituted 2,2'-Bipyridine

    Institute of Scientific and Technical Information of China (English)

    CAO, Qian-Yong(曹迁永); GAN, Xin(甘欣); FU, Wen-Fu(傅文甫)

    2004-01-01

    The mono- and binuclear Cu(Ⅰ) complexes with substituted 2,2'-bipyridine and iodide ligands, [CuL2]BF4 (L=4-methoxycarbonyl-6-(4-methylphenyl)-2,2'-bipyridine (a), 6-(4-hydroxymethylphenyl)-2,2'-bipyridine (b) and 6-(4-methoxylphenyl)-2,2'-bipyridine (c)) and [Cu2(μ-I)2L2] were prepared, and the crystal structures of the complexes were obtained from signal-crystal X-ray diffractional analysis. The spectroscopic properties of the complexes in dichloromethane are dominated by low energy MLCT bands from 360 to 650 nm. The electrochemical studies of mononuclear complexes reveal that the complexes have stable copper(Ⅰ) state.

  19. A robust metal-organic framework constructed from alkoxo-bridged binuclear nodes and hexamethylenetetramine spacers: crystal structure and sorption studies.

    Science.gov (United States)

    Ilyes, Elena; Florea, Mihaela; Madalan, Augustin M; Haiduc, Ionel; Parvulescu, Vasile I; Andruh, Marius

    2012-08-06

    A neutral 3D metal-organic framework, (3)(∞)[Cu(2)(mand)(2)(hmt)]·H(2)O (1), was constructed from binuclear Cu(2)O(2) alkoxo-bridged nodes, generated by the doubly deprotonated mandelic acid. The nodes are connected by hexamethylenetetramine (hmt) spacers, which act as biconnective bridging ligands, and by carboxylato groups. Channels are observed along the crystallographic c axis. The water molecules from the channels can be easily removed, preserving the architecture of the crystal, which is stable up to 280 °C. The Langmuir surface area was found to be 610 m(2) g(-1). The sorption ability of 1 was investigated using H(2) and CO(2).

  20. Density functional theory calculations on the complexation of p-arsanilic acid with hydrated iron oxide clusters: structures, reaction energies, and transition states.

    Science.gov (United States)

    Adamescu, Adrian; Hamilton, Ian P; Al-Abadleh, Hind A

    2014-07-31

    Aromatic organoarsenicals, such as p-arsanilic acid (pAsA), are still used today as feed additives in the poultry and swine industries in developing countries. Through the application of contaminated litter as a fertilizer, these compounds enter the environment and interact with reactive soil components such as iron and aluminum oxides. Little is known about these surface interactions at the molecular level. We report density functional theory (DFT) calculations on the energies, optimal geometries, and vibrational frequencies for hydrated pAsA/iron oxide complexes, as well as changes in Gibbs free energy, enthalpy, and entropy for various types of ligand exchange reactions leading to both inner- and outer-sphere complexes. Similar calculations using arsenate are also shown for comparison, along with activation barriers and transition state geometries between inner-sphere complexes. Minimum energy calculations show that the formation of inner- and outer-sphere pAsA/iron oxide complexes is thermodynamically favorable, with the monodentate mononuclear complexes being the most favorable. Interatomic As-Fe distances are calculated to be between 3.3 and 3.5 Å for inner-sphere complexes and between 5.2 and 5.6 Å for outer-sphere complexes. In addition, transition state calculations show that activation energies greater than 23 kJ/mol are required to form the bidentate binuclear pAsA/iron oxide complexes, and that formation of arsenate bidentate binuclear complexes is thermodynamically -rather than kinetically- driven. Desorption thermodynamics using phosphate ions show that reactions are most favorable using HPO4(2-) species. The significance of our results for the overall surface complexation mechanism of pAsA and arsenate is discussed.

  1. Axial ligand modulation of the electronic structures of binuclear copper sites: analysis of paramagnetic 1H NMR spectra of Met160Gln Cu(A).

    Science.gov (United States)

    Fernández, C O; Cricco, J A; Slutter, C E; Richards, J H; Gray, H B; Vila, A J

    2001-11-28

    Cu(A) is an electron-transfer copper center present in heme-copper oxidases and N2O reductases. The center is a binuclear unit, with two cysteine ligands bridging the metal ions and two terminal histidine residues. A Met residue and a peptide carbonyl group are located on opposite sides of the Cu2S2 plane; these weaker ligands are fully conserved in all known Cu(A) sites. The Met160Gln mutant of the soluble subunit II of Thermus thermophilus ba3 oxidase has been studied by NMR spectroscopy. In its oxidized form, the binuclear copper is a fully delocalized mixed-valence pair, as are all natural Cu(A) centers. The faster nuclear relaxation in this mutant suggests that a low-lying excited state has shifted to higher energies compared to that of the wild-type protein. The introduction of the Gln residue alters the coordination mode of His114 but does not affect His157, thereby confirming the proposal that the axial ligand-to-copper distances influence the copper-His interactions (Robinson, H.; Ang, M. C.; Gao, Y. G.; Hay, M. T.; Lu, Y.; Wang, A. H. Biochemistry 1999, 38, 5677). Changes in the hyperfine coupling constants of the Cys beta-CH2 groups are attributed to minor geometrical changes that affect the Cu-S-C(beta)-H(beta) dihedral angles. These changes, in addition, shift the thermally accessible excited states, thus influencing the spectral position of the Cys beta-CH2 resonances. The Cu-Cys bonds are not substantially altered by the Cu-Gln160 interaction, in contrast to the situation found in the evolutionarily related blue copper proteins. It is possible that regulatory subunits in the mitochondrial oxidases fix the relative positions of thermally accessible Cu(A) excited states by tuning axial ligand interactions.

  2. Precise investigation of the axial ligand substitution mechanism on a hydrogenphosphato-bridged lantern-type platinum(III) binuclear complex in acidic aqueous solution.

    Science.gov (United States)

    Iwatsuki, Satoshi; Mizushima, Chiho; Morimoto, Naoyuki; Muranaka, Shinji; Ishihara, Koji; Matsumoto, Kazuko

    2005-10-31

    Detailed equilibrium and kinetic studies on axial water ligand substitution reactions of the "lantern-type" platinum(III) binuclear complex, [Pt(2)(mu-HPO(4))(4)(H(2)O)(2)](2)(-), with halide and pseudo-halide ions (X(-) = Cl(-), Br(-), and SCN(-)) were carried out in acidic aqueous solution at 25 degrees C with I = 1.0 M. The diaqua Pt(III) dimer complex is in acid dissociation equilibrium in aqueous solution with -log K(h1) = 2.69 +/- 0.04. The consecutive formation constants of the aquahalo complex () and the dihalo complex () were determined spectrophotometrically to be log = 2.36 +/- 0.01 and log = 1.47 +/- 0.01 for the reaction with Cl(-) and log = 2.90 +/- 0.04 and log = 2.28 +/- 0.01 for the reaction with Br(-), respectively. In the kinetic measurements carried out under the pseudo-first-order conditions with a large excess concentration of halide ion compared to that of Pt(III) dimer (C(X)()- > C(Pt)), all of the reactions proceeded via a one-step first-order reaction, which is a contrast to the consecutive two-step reaction for the amidato-bridged platinum(III) binuclear complexes. The conditional first-order rate constant (k(obs)) depended on C(X)()- as well as the acidity of the solution. From kinetic analyses, the rate-limiting step was determined to be the first substitution process that forms the monohalo species, which is in rapid equilibrium with the dihalo complex. The reaction with 4-penten-1-ol was also kinetically investigated to examine the reactivity of the lantern complex with olefin compounds.

  3. Reaction mechanism for the highly efficient catalytic decomposition of peroxynitrite by the amphipolar iron(III) corrole 1-Fe.

    Science.gov (United States)

    Avidan-Shlomovich, Shlomit; Gross, Zeev

    2015-07-21

    The amphipolar iron(III) corrole 1-Fe is one of the most efficient catalysts for the decomposition of peroxynitrite, the toxin involved in numerous diseases. This research focused on the mechanism of that reaction at physiological pH, where peroxynitrite is in equilibrium with its much more reactive conjugated acid, by focusing on the elementary steps involved in the catalytic cycle. Kinetic investigations uncovered the formation of a reaction intermediate in a process that is complete within a few milliseconds (k1 ∼ 3 × 10(7) M(-1) s(-1) at 5 °C, about 7 orders of magnitude larger than the first order rate constant for the non-catalyzed process). Multiple evidence points towards iron-catalyzed homolytic O-O bond cleavage to form nitrogen dioxide and hydroxo- or oxo-iron(iv) corrole. The iron(iv) intermediate was found to decay via multiple pathways that proceed at similar rates (k2 about 10(6) M(-1) s(-1)): reaction with nitrogen dioxide to form nitrate, nitration of the corrole macrocyclic, and dimerization to binuclear iron(iv) corrole. Catalysis in the presence of substrates affects the decay of the iron intermediate by either oxidative nitration (phenolic substrates) or reduction (ascorbate). A large enough excess of ascorbate accelerates the catalytic decomposition of PN by 1-Fe by orders of magnitude, prevents other decay routes of the iron intermediate, and eliminates nitration products as well. This suggests that the beneficial effect of the iron corrole under the reducing conditions present in most biological media might be even larger than in the purely chemical system. The acquired mechanistic insight is of prime importance for the design of optimally acting catalysts for the fast and safe decomposition of reactive oxygen and nitrogen species.

  4. 武警某执勤部队膳食铁与血脂水平的相关性研究%Associations between intake of dietary iron and blood lipid in soldiers of Armed Police Forces

    Institute of Scientific and Technical Information of China (English)

    楚琳; 王磊; 李严; 李卉

    2015-01-01

    Objective To investigate the associations between intake of the dietary iron and blood lipid in the soldiers of Armed Police Forces .Methods Dietary survey for 3 days by dietary weighing method was made and the total iron content , heme-iron and non heme-iron intakes were counted in 115 soldiers.Fasting total cholesterol (TC), triglycerides (TG), HDL cholesterol (HDL-C) and LDL cholesterol ( LDL-C) were also measured .Logistic regression models and one-way ANOVA were used to assess associa-tions and prevalence between the total iron content , heme-iron and non heme-iron intakes and dyslipidemia risks after adjusting for age , BMI and energy consumption .Results The average iron intake was higher than the Chinese DRIs value .The total dietary iron , heme iron and non-heme iron contents were 47.1mg, 26.5mg and 19.9mg, respectively.The total dietary iron content and heme-iron were positively associated with the blood total cholesterol ( TC) , triglycerides ( TG) , and low density lipoprotein cholesterol ( LDL-C) ( P<0.05).With increasing dietary iron content and heme-iron, dyslipidemia risks were significantly increased .Conclusion Dietary iron from animal foods may have a bad effect on the blood lipid levels .%目的:研究武警某执勤部队战士膳食铁与血脂间的关系,为进一步提供合理膳食结构、保持机体血脂代谢平衡提供理论基础。方法115名战士作为调查对象,采用3 d称重法对其食堂伙食供应情况连续调查,计算其食物总铁元素、动物来源的血红素铁及植物来源的非血红素铁摄入量;取空腹静脉血,全自动生化分析仪检测血浆总胆固醇( total cholesterol , TC)、三酰甘油(triglycerides,TG)、高密度脂蛋白胆固醇(HDL cholesterol,HDL-C)和低密度脂蛋白胆固醇(LDL cholesterol, LDL-C),采用多元回归分析食物总铁元素、动物性食物来源的血红蛋白铁,以及植物性食物来源的非血红蛋白铁摄

  5. Iron supplements (image)

    Science.gov (United States)

    The mineral iron is an essential nutrient for humans because it is part of blood cells, which carry oxygen to all body cells. There is no conclusive evidence that iron supplements contribute to heart attacks.

  6. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... easily treated condition that occurs if you don't have enough iron in your body. Low iron ... can occur if your red blood cells don't contain enough hemoglobin (HEE-muh-glow-bin). Hemoglobin ...

  7. Binuclear cobalt(II), nickel(II), copper(II) and palladium(II) complexes of a new Schiff-base as ligand: synthesis, structural characterization, and antibacterial activity.

    Science.gov (United States)

    Geeta, B; Shravankumar, K; Reddy, P Muralidhar; Ravikrishna, E; Sarangapani, M; Reddy, K Krishna; Ravinder, V

    2010-11-01

    A binucleating new Schiff-base ligand with a phenylene spacer, afforded by the condensation of glycyl-glycine and o-phthalaldehyde has been served as an octadentate N₄O₄ ligand in designing some binuclear complexes of cobalt(II), nickel(II), copper(II), and palladium(II). The binding manner of the ligand to the metal and the composition and geometry of the metal complexes were examined by elemental analysis, conductivity measurements, magnetic moments, IR, ¹H, ¹³C NMR, ESR and electronic spectroscopies, and TGA measurements. There are two different coordination/chelation environments present around two metal centers of each binuclear complex. The composition of the complexes in the coordination sphere was found to be [M₂(L)(H(2)O)₄] (where M=Co(II) and Ni(II)) and [M₂(L)] (where M=Cu(II) and Pd(II)). In the case of Cu(II) complexes, ESR spectra provided further information to confirm the binuclear structure and the presence of magnetic interactions. All the above metal complexes have shown moderate to good antibacterial activity against Gram-positive and Gram-negative bacteria.

  8. Iron age: novel targets for iron overload.

    Science.gov (United States)

    Casu, Carla; Rivella, Stefano

    2014-12-05

    Excess iron deposition in vital organs is the main cause of morbidity and mortality in patients affected by β-thalassemia and hereditary hemochromatosis. In both disorders, inappropriately low levels of the liver hormone hepcidin are responsible for the increased iron absorption, leading to toxic iron accumulation in many organs. Several studies have shown that targeting iron absorption could be beneficial in reducing or preventing iron overload in these 2 disorders, with promising preclinical data. New approaches target Tmprss6, the main suppressor of hepcidin expression, or use minihepcidins, small peptide hepcidin agonists. Additional strategies in β-thalassemia are showing beneficial effects in ameliorating ineffective erythropoiesis and anemia. Due to the suppressive nature of the erythropoiesis on hepcidin expression, these approaches are also showing beneficial effects on iron metabolism. The goal of this review is to discuss the major factors controlling iron metabolism and erythropoiesis and to discuss potential novel therapeutic approaches to reduce or prevent iron overload in these 2 disorders and ameliorate anemia in β-thalassemia.

  9. Mechanism of Arsenic Sequestration in High-Iron Sediments

    Science.gov (United States)

    Root, R. A.; Campbell, K. M.; Hering, J. G.; O'Day, P. A.

    2005-12-01

    iron(III) oxides or reduced iron(II,III) oxide, were not observed in the sediments. EXAFS data showed that the arsenic within sediments is bonded directly to iron octahedra as binuclear bidentate complexes. Within the sediments, arsenic reduces from As(V) to As(III) at or just below the sediment/water interface, but there is no significant change in local bonding of arsenic observed in the EXAFS. Likewise, there are no apparent changes in iron mineralogy or oxidation state as a function of depth. Based on the mineralogy and surface complexation observed, the potential for release of arsenic into the sediment porewaters should be small. However, gel probe analysis has shown that arsenic is released to the porewaters at depth. Previous studies at this site, and the new sequential extraction and XAS data, indicate that the mechanism of arsenic release is not a consequence of the transformation of As(V) to As(III), but is a result of reductive dissolution of the host iron phase.

  10. Iron deficiency anemia

    OpenAIRE

    Naigamwalla, Dinaz Z.; Webb, Jinelle A.; Giger, Urs

    2012-01-01

    Iron is essential to virtually all living organisms and is integral to multiple metabolic functions. The most important function is oxygen transport in hemoglobin. Iron deficiency anemia in dogs and cats is usually caused by chronic blood loss and can be discovered incidentally as animals may have adapted to the anemia. Severe iron deficiency is characterized by a microcytic, hypochromic, potentially severe anemia with a variable regenerative response. Iron metabolism and homeostasis will be ...

  11. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... the NHLBI on Twitter. What Is Iron-Deficiency Anemia? Español Iron-deficiency anemia is a common, easily ... Featured Video Living With and Managing Iron-Deficiency Anemia 05/18/2011 This video—presented by the ...

  12. Iron-Deficiency Anemia

    Science.gov (United States)

    ... the NHLBI on Twitter. What Is Iron-Deficiency Anemia? Español Iron-deficiency anemia is a common, easily ... Featured Video Living With and Managing Iron-Deficiency Anemia 05/18/2011 This video—presented by the ...

  13. Iron-Deficiency Anemia

    Science.gov (United States)

    ... page from the NHLBI on Twitter. What Is Iron-Deficiency Anemia? Español Iron-deficiency anemia is a common, ... Content: NEXT >> Featured Video Living With and Managing Iron-Deficiency Anemia 05/18/2011 This video—presented by ...

  14. Binuclear Cu(A) Formation in Biosynthetic Models of Cu(A) in Azurin Proceeds via a Novel Cu(Cys)2His Mononuclear Copper Intermediate.

    Science.gov (United States)

    Chakraborty, Saumen; Polen, Michael J; Chacón, Kelly N; Wilson, Tiffany D; Yu, Yang; Reed, Julian; Nilges, Mark J; Blackburn, Ninian J; Lu, Yi

    2015-10-06

    Cu(A) is a binuclear electron transfer (ET) center found in cytochrome c oxidases (CcOs), nitrous oxide reductases (N₂ORs), and nitric oxide reductase (NOR). In these proteins, the Cu(A) centers facilitate efficient ET (kET > 10⁴s⁻¹) under low thermodynamic driving forces (10-90 mV). While the structure and functional properties of Cu(A) are well understood, a detailed mechanism of the incorporation of copper into the protein and the identity of the intermediates formed during the Cu(A) maturation process are still lacking. Previous studies of the Cu(A) assembly mechanism in vitro using a biosynthetic model Cu(A) center in azurin (Cu(A)Az) identified a novel intermediate X (Ix) during reconstitution of the binuclear site. However, because of the instability of Ix and the coexistence of other Cu centers, such as Cu(A)' and type 1 copper centers, the identity of this intermediate could not be established. Here, we report the mechanism of Cu(A) assembly using variants of Glu114XCuAAz (X = Gly, Ala, Leu, or Gln), the backbone carbonyl of which acts as a ligand to the Cu(A) site, with a major focus on characterization of the novel intermediate Ix. We show that Cu(A) assembly in these variants proceeds through several types of Cu centers, such as mononuclear red type 2 Cu, the novel intermediate Ix, and blue type 1 Cu. Our results show that the backbone flexibility of the Glu114 residue is an important factor in determining the rates of T2Cu → Ix formation, suggesting that Cu(A) formation is facilitated by swinging of the ligand loop, which internalizes the T2Cu capture complex to the protein interior. The kinetic data further suggest that the nature of the Glu114 side chain influences the time scales on which these intermediates are formed, the wavelengths of the absorption peaks, and how cleanly one intermediate is converted to another. Through careful understanding of these mechanisms and optimization of the conditions, we have obtained Ix in ∼80

  15. Macrophages and Iron Metabolism.

    Science.gov (United States)

    Soares, Miguel P; Hamza, Iqbal

    2016-03-15

    Iron is a transition metal that due to its inherent ability to exchange electrons with a variety of molecules is essential to support life. In mammals, iron exists mostly in the form of heme, enclosed within an organic protoporphyrin ring and functioning primarily as a prosthetic group in proteins. Paradoxically, free iron also has the potential to become cytotoxic when electron exchange with oxygen is unrestricted and catalyzes the production of reactive oxygen species. These biological properties demand that iron metabolism is tightly regulated such that iron is available for core biological functions while preventing its cytotoxic effects. Macrophages play a central role in establishing this delicate balance. Here, we review the impact of macrophages on heme-iron metabolism and, reciprocally, how heme-iron modulates macrophage function.

  16. [Iron function and carcinogenesis].

    Science.gov (United States)

    Akatsuka, Shinya; Toyokuni, Shinya

    2016-07-01

    Though iron is an essential micronutrient for humans, the excess state is acknowledged to be associated with oncogenesis. For example, iron overload in the liver of the patients with hereditary hemocromatosis highly increases the risk of hepatocellular carcinoma. Also, as to asbestos-related mesothelioma, such kinds of asbestos with a higher iron content are considered to be more carcinogenic. Iron is a useful element, which enables fundamental functions for life such as oxygen carrying and electron transport. However, in the situation where organisms are unable to have good control of it, iron turns into a dangerous element which catalyzes generation of reactive oxygen. In this review, I first outline the relationships between iron and cancer in general, then give an explanation about iron-related animal carcinogenesis models.

  17. Biodisponibilidade de ferro em diferentes compostos para leitões desmamados aos 21 dias de idade Bioavailability of iron in different compounds for piglets weaned at 21 days old

    Directory of Open Access Journals (Sweden)

    Maria Lúcia Cocato

    2008-12-01

    Full Text Available Avaliou-se a biodisponibilidade de ferro de diferentes compostos visando sua utilização em dietas para leitões desmamados. Utilizaram-se 44 leitões (7 não-anêmicos e 37 anêmicos desmamados aos 21 dias de idade (7,3 ± 1,8 kg e distribuídos em dois grupos: grupo não-anêmico e grupo anêmico. Durante sete dias, os animais do grupo não-anêmico receberam dieta com FeSO4.7H2O (sulfato ferroso hepta-hidratado na dose de 100 mg/kg e os do grupo anêmico, dieta sem ferro (Iron bioavailability from different compounds was evaluated to be used in diets for weaned piglets. Forty four piglets (7 non-anemic and 37 anemic weaned at 21 days old (7.3 ± 1.8 kg were distributed into two groups: non-anemic group and anemic group. During seven days, the animals from non-anemic group were fed diet with ferrous sulfate hepthydrate (FeSO4.7H2O in the dose of 100 mg/kg and of the anemic group, diet without iron (<15 mg/kg diet. On the seventh day, after the determination blood hemoglobin concentration and diagnosed with anemia, piglets were grouped according to product of the weight (kg × hemoglobin (g/dL and individually housed, for 13 days in cages for digestibility studies, where they were fed with six diets based on corn and powdered milk: three standard diets with FeSO4.7H2O in equivalent amount of 80, 150 and 200 mg Fe/kg diet; two experimental diets, one with iron (150 mg/kg in form of FeSO4 microencapsulated with carboxymethylcellulose and other chelated with methionine, and a control diet with iron (100 mg/kg. In the days 0, 3, 6, 9 and 13 of the repletion period, the animals were weighed for performance evaluation and blood was collected to determine the hemoglobin concentration. At the end, the animals were slaughtered and liver was collected for determination of total iron concentrations, Fe-heme and Fe non-heme. Liver concentrations of Fe-heme, Fe non-heme and Fe-total did not differ among animals, however, the control group showed excess of

  18. New rat models of iron sucrose-induced iron overload.

    Science.gov (United States)

    Vu'o'ng Lê, Bá; Khorsi-Cauet, Hafida; Villegier, Anne-Sophie; Bach, Véronique; Gay-Quéheillard, Jérôme

    2011-07-01

    The majority of murine models of iron sucrose-induced iron overload were carried out in adult subjects. This cannot reflect the high risk of iron overload in children who have an increased need for iron. In this study, we developed four experimental iron overload models in young rats using iron sucrose and evaluated different markers of iron overload, tissue oxidative stress and inflammation as its consequences. Iron overload was observed in all iron-treated rats, as evidenced by significant increases in serum iron indices, expression of liver hepcidin gene and total tissue iron content compared with control rats. We also showed that total tissue iron content was mainly associated with the dose of iron whereas serum iron indices depended essentially on the duration of iron administration. However, no differences in tissue inflammatory and antioxidant parameters from controls were observed. Furthermore, only rats exposed to daily iron injection at a dose of 75 mg/kg body weight for one week revealed a significant increase in lipid peroxidation in iron-treated rats compared with their controls. The present results suggest a correlation between iron overload levels and the dose of iron, as well as the duration and frequency of iron injection and confirm that iron sucrose may not play a crucial role in inflammation and oxidative stress. This study provides important information about iron sucrose-induced iron overload in rats and may be useful for iron sucrose therapy for iron deficiency anemia as well as for the prevention and diagnosis of iron sucrose-induced iron overload in pediatric patients.

  19. Novel binuclear μ-oxo diruthenium complexes combined with ibuprofen and ketoprofen: Interaction with relevant target biomolecules and anti-allergic potential.

    Science.gov (United States)

    Seuanes, Gabriela Campos; Moreira, Mariete Barbosa; Petta, Tânia; de Moraes Del Lama, Maria Perpétua Freire; de Moraes, Luiz Alberto Beraldo; de Oliveira, Anderson Rodrigo Moraes; Naal, Rose Mary Zumstein Georgetto; Nikolaou, Sofia

    2015-12-01

    This work presents the synthesis and characterization of two novel binuclear ruthenium compounds of general formula [Ru2O(carb)2(py)6](PF6)2, where py=pyridine and carb are the non-steroidal anti-inflammatory drugs ibuprofen (1) and ketoprofen (2). Both complexes were characterized by ESI-MS/MS spectrometry. The fragmentation patterns, which confirm the proposed structures, are presented. Besides that, compounds 1 and 2 present the charge transfer transitions within 325-330nm; and the intra-core transitions around 585nm, which is the typical spectra profile for [Ru2O] analogues. This suggests the carboxylate bridge has little influence in their electronic structure. The effects of the diruthenium complexes on Ig-E mediated mast cell activation were evaluated by measuring the enzyme β-hexosaminidase released by mast cells stimulated by antigen. The inhibitory potential of the ketoprofen complex against mast cell stimulation suggests its promising application as a therapeutic agent for treating or preventing IgE-mediated allergic diseases. In addition, in vitro metabolism assays had shown that the ibuprofen complex is metabolized by the cytochrome P450 enzymes.

  20. Antioxidation and DNA-binding properties of binuclear lanthanide(III) complexes with a Schiff base ligand derived from 8-hydroxyquinoline-7-carboxaldehyde and benzoylhydrazine.

    Science.gov (United States)

    Liu, Yongchun; Zhang, Kejun; Wu, Yun; Zhao, Junying; Liu, Jianning

    2012-08-01

    8-Hydroxyquinoline-7-carboxaldehyde (8-HQ-7-CA), Schiff-base ligand 8-hydroxyquinoline-7-carboxaldehyde benzoylhydrazone, and binuclear complexes [LnL(NO(3))(H(2)O)(2)](2) were prepared from the ligand and equivalent molar amounts of Ln(NO(3))·6H(2)O (Ln=La(3+), Nd(3+), Sm(3+), Eu(3+), Gd(3+), Dy(3+), Ho(3+), Er(3+), Yb(3+), resp.). Ligand acts as dibasic tetradentates, binding to Ln(III) through the phenolate O-atom, N-atom of quinolinato unit, and C=N and -O-C=N- groups of the benzoylhydrazine side chain. Dimerization of this monomeric unit occurs through the phenolate O-atoms leading to a central four-membered (LnO)(2) ring. Ligand and all of the Ln(III) complexes can strongly bind to CT-DNA through intercalation with the binding constants at 10(5)-10(6) M(-1). Moreover, ligand and all of the Ln(III) complexes have strong abilities of scavenging effects for hydroxyl (HO·) radicals. Both the antioxidation and DNA-binding properties of Ln(III) complexes are much better than that of ligand.

  1. Mono-nuclear copper complexes mimicking the intermediates for the binuclear copper center of the subunit II of cytochrome oxidase: a peptide based approach.

    Science.gov (United States)

    Dutta Gupta, Dwaipayan; Usharani, Dandamudi; Mazumdar, Shyamalava

    2016-11-28

    Three stable copper complexes of peptides derived from the copper ion binding loop of the subunit II of cytochrome c oxidase have been prepared and characterized by various spectroscopic techniques. These stable copper complexes of peptides were found to exhibit cysteine, histidine and/or methionine ligation, which has predominant σ-contribution in the Cys-Cu charge transfer. The copper(ii) peptide complexes showed type-2 EPR spectra, which is uncommon in copper-cysteinate complexes. UV-visible spectra, Raman and EPR results support a tetragonal structure of the coordination geometry around the copper ion. The copper complex of the 9-amino acid peptide suggested the formation of a 'red' copper center while the copper complexes of the 12- and 11-amino acid peptides showed the formation of a 'green' copper center. The results provide insights on the first stable models of the copper complexes formed in the peptide scaffold that mimic the mono-nuclear copper bound protein intermediates proposed during the formation of the binuclear Cu2S2 core of the enzyme. These three copper complexes of peptides derived from the metal ion binding loop of the CuA center of the subunit II of cytochrome c oxidase showed novel spectroscopic properties which have not so far been reported in any stable small complex.

  2. Spectral characterization, optical band gap calculations and DNA binding of some binuclear Schiff-base metal complexes derived from 2-amino-ethanoic acid and acetylacetone

    Science.gov (United States)

    Hussien, Mostafa A.; Nawar, Nagwa; Radwan, Fatima M.; Hosny, Nasser Mohammed

    2015-01-01

    Bi-nuclear metal complexes derived from the reaction of Cu(II), Co(II), Ni(II) and Zn(II) acetates with the Schiff-base ligand (H2L) resulted from the condensation of 2-amino-ethanoic acid (glycine) and acetylacetone have been synthesized and characterized by elemental analyses, Raman spectra, FT-IR, ES-MS, UV-Vis., 1H NMR, ESR, thermal analyses (TG, DTG and DTA) and magnetic measurements. The results showed that, the Schiff base ligand can bind two metal ions in the same time. It coordinates to the first metal ion as mono-negative bi-dentate through azomethine nitrogen and enolic carbonyl after deprotonation. At the same time, it binds to the second metal ion via carboxylate oxygen after deprotonation. The thermodynamic parameters E∗, ΔH∗, ΔG∗ and ΔS∗ have been calculated by Coats-Redfern (CR) and Horowitz-Metzger (HM) methods. The optical band gaps of the isolated complexes have been calculated from absorption spectra and the results indicated semi-conducting nature of the investigated complexes. The interactions between the copper (II) complex and calf thymus DNA (CT-DNA) have been studied by UV spectra. The results confirm that the Cu(II) complex binds to CT-DNA.

  3. A Selective Membrane Electrode for Thiocyanate Ion Based on a Bis-taurine-salicylic Binuclear Copper(Ⅱ) Complex as Ionophore

    Institute of Scientific and Technical Information of China (English)

    王福昌; 柴雅琴; 袁若; 陈春华; 戴建远; 徐岚

    2005-01-01

    The response characteristics of a new potentiometric membrane electrode with unique selectivity towards thiocyanate ion were reported. The electrode was prepared by incorporating bis-taurine-salicylic binuclear copper(Ⅱ) complex into a plasticized PVC-membrane. The resulting electrode exhibits anti-Hofmeister selectivity sequence: SCN->I-> ClO4- >Sal-> NO3- > NO2- >Br->Cl-> SO3- > SO42- and a near-Nernstian potential linear range for thiocyanate from 1.0×10-1 to 1.0× 10-6 mol·L-1 with a detection limit of 8.0× 10-7 mol·L-1 and a slope of - 56.5 mV/PCSCN- in phosphate buffer solution of pH 5.0 at 20 ℃. The UV/Vis spectra, IR spectroscopy and AC impedance studies showed that the excellent selectivity to thiocyanate was related to the unique interaction between the central metal and the analyte and a steric effect associated with the structure of the carrier. The electrode was successfully applied to the determination of thiocyanate in waste water and human urine samples.

  4. Analytical development of a binuclear oxo-manganese complex bio-inspired on oxidase enzyme for doping control analysis of acetazolamide.

    Science.gov (United States)

    Machini, Wesley B S; Teixeira, Marcos F S

    2016-05-15

    A bio-inspired electrochemical sensor using a binuclear oxo-manganese complex was evaluated and applied in the detection of a substance associated with doping in sports: acetazolamide (ACTZ). Investigation was made of the influence of different experimental variables on the electrocatalytic oxidation of ACTZ by the bio-inspired sensor, such as pH and interfering species. The bio-inspired sensor showed the best response in the range from 5.00×10(-9) to 7.00×10(-8) mol L(-1) ACTZ, with a linear range from 5.00×10(-9) to 2.50×10(-8) mol L(-1) and a detection limit of 4.76×10(-9) mol L(-1). The sensor exhibited characteristics similar to the Michaelis-Menten model of an enzymatic electrode, due to the use of a multinucleated complex of manganese with μ-oxo units, which was able to mimic the properties of enzymes with manganese as a cofactor in their composition, such as Mn-containing oxidase. The determination of ACTZ with the bio-inspired sensor was evaluated using three different synthetic biological fluids (plasma, saliva, and urine), demonstrating its viability for use with real samples. The analysis of ACTZ in real urine samples using the bio-inspired sensor, simulating the method adopted by the World Anti-Doping Agency, which revealed viable, suggesting a new and promising platform to be used in these analysis.

  5. Synthesis, spectroscopic, thermal and DFT calculations of 2-(3-amino-2-hydrazono-4-oxothiazolidin-5-yl) acetic acid binuclear metal complexes.

    Science.gov (United States)

    Hassan, Walid M I; Badawy, M A; Mohamed, Gehad G; Moustafa, H; Elramly, Salwa

    2013-07-01

    The binuclear complexes of 2-(3-amino-2-hydrazono-4-oxothiazolidin-5-yl) acetic acid ligand (HL) with Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) ions were prepared and their stoichiometry was determined by elemental analysis. The stereochemistry of the studied series of metal complexes was established by analyzing their infrared, (1)H NMR spectra and the magnetic moment measurements. According to the elemental analysis data, the complexes were found to have the formulae [Fe2L(H2O)8]Cl5 and [M2L(H2O)8]Cl3 (M=Co(II), Ni(II), Cu(II) and Zn(II)). The present analyses demonstrate that all metal ions coordinated to the ligand via O(9), O(11), N(16) and N(18) atoms. Thermal decomposition studies of the ligand-metal complexes have been performed to verify the status of water molecules present in these metal complexes and their general decomposition pattern. Density Functional Theory (DFT) calculations at the B3LYP/6-31G(*) level of theory have been carried out to investigate the equilibrium geometry of the ligand and complexes. Moreover, charge density distribution, extent of distortion from regular geometry, dipole moment and orientation have been performed and discussed.

  6. Synthesis, crystal structure and magnetic properties of the binuclear copper (Ⅱ) complex of a new bis ( 1,4, 7, 10-tetraazacy-clododecane) ligand

    Institute of Scientific and Technical Information of China (English)

    XU, Qiang(徐强); DU, Miao(杜淼); ZHANG, Ruo-Hua(张若桦); SHEN, Hao-Yu(沈昊宇); BU, Xian-He(卜显和); BU, Wei-Ming(卜卫名)

    2000-01-01

    A new binucleating macrocyclic ligand 2,6-bis(1,4,7, 10-te-traazacyclododecan-10-ylmethyl)methoxy-benzene (L) and its binuclearcopper(Ⅱ) complex, [Cu2LBr2] (ClO4)2 · 3H2O (1), was prepared and the structure was determined by Xray crystallography. Complex 1 crystallizes in monoclinic crystal system, P21/n space group with a = 0.8206(3), b =2.0892(8), c=2.3053(7) nm, β=95.83(2)°, V=3.932nm3, Mr=1017.57, Z=4, Dc=1.692g/cm3, and R=0.0489, Rw=0.0552 for 6571 observed reflections with I≥2σ(Ⅰ). Both of the copper(Ⅱ) centers are coordinated by four amine nitrogen donors of cyclen subunits and a bromide anion, and each copper(H) ion is in a square-pyramidal coordination environment. Variable temperature magnetic susceptibility studies indicate that there exists weak intramolecular antiferro- magnetic coupling ( - 2J= 2.06 cm-1) between the two copper(Ⅱ) centers.Keyword Binuclear copper(Ⅱ) complex, crystal structure,antiferro-magnetic coupling, binucleating macrocyclic ligand

  7. DNA-binding, catalytic oxidation, C—C coupling reactions and antibacterial activities of binuclear Ru(II thiosemicarbazone complexes: Synthesis and spectral characterization

    Directory of Open Access Journals (Sweden)

    Arumugam Manimaran

    2012-07-01

    Full Text Available New hexa-coordinated binuclear Ru(II thiosemicarbazone complexes of the type {[(B(EPh3(COClRu]2L} (where, E = P or As; B = PPh3 or AsPh3 or pyridine; L = mononucleating NS donor of N-substituted thiosemicarbazones have been synthesized and characterized by elemental analysis, FT-IR, UV–vis and 31P{1H} NMR cyclic voltammetric studies. The DNA-binding studies of Ru(II complexes with calf thymus DNA (CT-DNA were investigated by UV–vis, viscosity measurements, gel-electrophoresis and fluorescence spectroscopy. The new complexes have been used as catalysts in C—C coupling reaction and in the oxidation of alcohols to their corresponding carbonyl compounds by using NMO as co-oxidant and molecular oxygen (O2 atmosphere at ambient temperature. Further, the new binucleating thiosemicarbazone ligands and their Ru(II complexes were also screened for their antibacterial activity against Klebsiella pneumoniae, Shigella sp., Micrococcus luteus, Escherichia coli and Salmonella typhi. From this study, it was found out that the activity of the complexes almost reaches the effectiveness of the conventional bacteriocide.

  8. Studies with an immobilized metal affinity chromatography cassette system involving binuclear triazacyclononane-derived ligands: automation of batch adsorption measurements with tagged recombinant proteins.

    Science.gov (United States)

    Petzold, Martin; Coghlan, Campbell J; Hearn, Milton T W

    2014-07-18

    This study describes the determination of the adsorption isotherms and binding kinetics of tagged recombinant proteins using a recently developed IMAC cassette system and employing automated robotic liquid handling procedures for IMAC resin screening. These results confirm that these new IMAC resins, generated from a variety of different metal-charged binuclear 1,4,7-triaza-cyclononane (tacn) ligands, interact with recombinant proteins containing a novel N-terminal metal binding tag, NT1A, with static binding capacities similar to those obtained with conventional hexa-His tagged proteins, but with significantly increased association constants. In addition, higher kinetic binding rates were observed with these new IMAC systems, an attribute that can be positively exploited to increase process productivity. The results from this investigation demonstrate that enhancements in binding capacities and affinities were achieved with these new IMAC resins and chosen NT1A tagged protein. Further, differences in the binding performances of the bis(tacn) xylenyl-bridged ligands were consistent with the distance between the metal binding centres of the two tacn moieties, the flexibility of the ligand and the potential contribution from the aromatic ring of the xylenyl group to undergo π/π stacking interactions with the tagged proteins.

  9. Synthesis, Characterization, and Biological Studies of Binuclear Copper(II Complexes of (2E-2-(2-Hydroxy-3-Methoxybenzylidene-4N-Substituted Hydrazinecarbothioamides

    Directory of Open Access Journals (Sweden)

    P. Murali Krishna

    2013-01-01

    Full Text Available Four novel binuclear copper(II complexes [1–4] of (2E-2-(2-hydroxy-3-methoxybenzylidene-4N-substituted hydrazinecarbothioamides, (OH(OCH3C6H4CH=NNHC(SNHR, where R = H (L1, Me (L2, Et (L3, or Ph (L4, have been synthesized and characterized. The FT-IR spectral data suggested the attachment of copper(II ion to ligand moiety through the azomethine nitrogen, thioketonic sulphur, and phenolic-O. The spectroscopic characterization indicates the dissociation of dimeric complex into mononuclear [Cu(LCl] units in polar solvents like DMSO, where L is monoanionic thiosemicarbazone. The DNA binding properties of the complexes with calf thymus (CT DNA were studied by spectroscopic titration. The complexes show binding affinity to CT DNA with binding constant (Kb values in the order of 106 M−1. The ligands and their metal complexes were tested for antibacterial and antifungal activities by agar disc diffusion method. Except for complex 4, all complexes showed considerable activity almost equal to the activity of ciprofloxacin. These complexes did not show any effect on Gram-negative bacteria, whereas they showed moderate activity for Gram-positive strains.

  10. Inhibition of Aβ42 peptide aggregation by a binuclear ruthenium(II)-platinum(II) complex: Potential for multi-metal organometallics as anti-amyloid agents.

    Science.gov (United States)

    Kumar, Amit; Moody, Lamaryet; Olaivar, Jason F; Lewis, Nerissa A; Khade, Rahul L; Holder, Alvin A; Zhang, Yong; Rangachari, Vijayaraghavan

    2010-08-23

    Design of inhibitors for amyloid-β (Aβ) peptide aggregation has been widely investigated over the years towards developing viable therapeutic agents for Alzheimer's disease (AD). The biggest challenge seems to be inhibiting Aβ aggregation at the early stages of aggregation possibly at the monomeric level, as oligomers are known to be neurotoxic. In this regard, exploiting the metal chelating property of Aβ to generate molecules that can overcome this impediment presents some promise. Recently, one such metal complex containing Pt(II) ([Pt(BPS)Cl(2)]) was reported to effectively inhibit Aβ42 aggregation and toxicity (1). This complex was able bind to Aβ42 at the N-terminal part of the peptide and triggered a conformational change resulting in effective inhibition. In the current report, we have generated a mixed-binuclear metal complex containing Pt(II) and Ru(II) that inhibited Aβ42 aggregation at an early stage of aggregation and seemed to have different modes of interaction than the previously reported Pt(II) complex, suggesting an important role of the second metal center. This 'proof-of-concept' compound will help in developing more effective molecules against Aβ aggregation by modifying the two metal centers as well as their ligands, which will open doors to new rationale for Aβ inhibition.

  11. Antibacterial Activities of Newly Synthesized Azo Anils And its Oxalato-Bridged Binuclear {Cu(II and Zn(II} Complexes

    Directory of Open Access Journals (Sweden)

    M. Ameen

    2014-12-01

    Full Text Available Novel oxalato-bridged binuclear metal {Cu(II and Zn(II} complexes; [{(L1M(II}2OX] (L1= 2-({2-hydroxy-5-[(4-nitrophenyldiazenyl]benzylidene}aminobenzoic acid, OX = oxalate and [{(L2M(II}2OX], (L2 = 2-{[(2-hydroxyphenylimino]methyl}-4-[(4-nitrophenyldiazenyl] phenol, OX = oxalate were synthesized. Azo anils and corresponding Metal {Cu((II and Zn(II} complexes were characterised by Elemental Combustion System, Atomic Absorption Spectroscopy (AAS, Fourier Transform Infrared (FTIR spectroscopy, UV-Visible, Spectroscopy and 13C-1H-Nuclear Magnetic Resonance spectroscopy. Elemental Analyses, FTIR and UV-Vis were used for structural characterization of metal complexes and distorted octahedral geometry for M(II complexes came into being. The antibacterial activities of azo anils ligands, oxalate ion, CuCl2.2H2O, Zn(CH3COO2.2H2O and metal {Cu(II and Zn(II} complexes against gram-positive (Bacillis subtilis and gram-negative (Escherichia coli were evaluated. The antibacterial activities were performed to asses inhibition potential of ligand and their metal {Cu(II and Zn(II} complexes. The results revealed that antibacterial activities of azo anils become more pronounced when free ligands were coordinated to central metal atom.

  12. Iron chelating agents for iron overload diseases

    Directory of Open Access Journals (Sweden)

    Guido Crisponi

    2014-09-01

    Full Text Available Although iron is an essential element for life, an excessive amount may become extremely toxic both for its ability to generate reactive oxygen species, and for the lack in humans of regulatory mechanisms for iron excretion. Chelation therapy has been introduced in clinical practice in the seventies of last century to defend thalassemic patients from the effects of iron overload and, in spite of all its limitations, it has dramatically changed both life expectancy and quality of life of patients. It has to be considered that the drugs in clinical use present some disadvantages too, this makes urgent new more suitable chelating agents. The requirements of an iron chelator have been better and better defined over the years and in this paper they will be discussed in detail. As a final point the most interesting ligands studied in the last years will be presented.

  13. Towards advanced structural analysis of iron oxide clusters on the surface of γ-Al2O3 using EXAFS

    Science.gov (United States)

    Boubnov, Alexey; Roppertz, Andreas; Kundrat, Matthew D.; Mangold, Stefan; Reznik, Boris; Jacob, Christoph R.; Kureti, Sven; Grunwaldt, Jan-Dierk

    2016-11-01

    Iron oxide centres are structurally investigated in 0.1% Fe/γ-Al2O3, which is known as highly active catalyst, for instance in the oxidation of CO. The sample was characterised by using X-ray absorption spectroscopy (XAS) in terms of X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS), Mössbauer spectroscopy, X-ray diffraction (XRD) and transmission electron microscopy (TEM). These analyses evidenced high dispersion of the iron oxide entities without significant presence of bulk-like aggregates associated with the low Fe content of the catalyst. A library of structural models of Al2O3-supported surface Fe was created as input for EXAFS fitting. Additionally, several model structures of Fe substituting Al ions in bulk γ-Al2O3 were created with optimised geometry based on density-functional theory (DFT) calculations. From EXAFS refinement of the best 8 out of 24 models, it was found that the trivalent Fe ions are coordinated by 4-5 oxygen atoms and are located on octahedral lattice sites of the exposed surfaces of γ-Al2O3. These iron oxide species exist mainly as a mixture of monomeric and binuclear species and due to the low concentration represent suitable model systems as alternative to single crystal systems for structure-function relationships.

  14. The ubiquity of iron.

    Science.gov (United States)

    Frey, Perry A; Reed, George H

    2012-09-21

    The importance of iron in living systems can be traced to the many complexes within which it is found, to its chemical mobility in undergoing oxidation-reduction reactions, and to the abundance of iron in Earth's crust. Iron is the most abundant element, by mass, in the Earth, constituting about 80% of the inner and outer cores of Earth. The molten outer core is about 8000 km in diameter, and the solid inner core is about 2400 km in diameter. Iron is the fourth most abundant element in Earth's crust. It is the chemically functional component of mononuclear iron complexes, dinuclear iron complexes, [2Fe-2S] and [4Fe-4S] clusters, [Fe-Ni-S] clusters, iron protophorphyrin IX, and many other complexes in protein biochemistry. Metals such as nickel, cobalt, copper, and manganese are present in the crust and could in principle function chemically in place of iron, but they are scarce in Earth's crust. Iron is plentiful because of its nuclear stability in stellar nuclear fusion reactions. It seems likely that other solid planets, formed by the same processes as Earth, would also foster the evolution of life and that iron would be similarly important to life on those planets as it is on Earth.

  15. Iron deficiency anaemia.

    Science.gov (United States)

    Lopez, Anthony; Cacoub, Patrice; Macdougall, Iain C; Peyrin-Biroulet, Laurent

    2016-02-27

    Anaemia affects roughly a third of the world's population; half the cases are due to iron deficiency. It is a major and global public health problem that affects maternal and child mortality, physical performance, and referral to health-care professionals. Children aged 0-5 years, women of childbearing age, and pregnant women are particularly at risk. Several chronic diseases are frequently associated with iron deficiency anaemia--notably chronic kidney disease, chronic heart failure, cancer, and inflammatory bowel disease. Measurement of serum ferritin, transferrin saturation, serum soluble transferrin receptors, and the serum soluble transferrin receptors-ferritin index are more accurate than classic red cell indices in the diagnosis of iron deficiency anaemia. In addition to the search for and treatment of the cause of iron deficiency, treatment strategies encompass prevention, including food fortification and iron supplementation. Oral iron is usually recommended as first-line therapy, but the most recent intravenous iron formulations, which have been available for nearly a decade, seem to replenish iron stores safely and effectively. Hepcidin has a key role in iron homoeostasis and could be a future diagnostic and therapeutic target. In this Seminar, we discuss the clinical presentation, epidemiology, pathophysiology, diagnosis, and acute management of iron deficiency anaemia, and outstanding research questions for treatment.

  16. Colour Metallography of Cast Iron

    Institute of Scientific and Technical Information of China (English)

    Zhou Jiyang; Liu Jincheng

    2010-01-01

    @@ Chapter 3 Spheroidal Graphite Cast Iron(I) Spheroidal Graphite Cast Iron, SG iron in short, refers to the cast iron in which graphite precipitates as spheroidal shape during solidification of liquid iron. The graphite in common commercial cast iron can only be changed from flake to spheroidal shape by spheroidising treatment. Since spheroidal graphite reduces the cutting effect of stress concentration, the metal matrix strength of SG iron can be applied around 70%-90%, thus the mechanical property of SG iron is significantly superior to other cast irons;even the tensile strength of SG iron is higher than that carbon steel.

  17. Iron and Stony-iron Meteorites

    Science.gov (United States)

    Haack, H.; McCoy, T. J.

    2003-12-01

    Without iron and stony-iron meteorites, our chances of ever sampling the deep interior of a differentiated planetary object would be next to nil. Although we live on a planet with a very substantial core, we will never be able to sample it. Fortunately, asteroid collisions provide us with a rich sampling of the deep interiors of differentiated asteroids.Iron and stony-iron meteorites are fragments of a large number of asteroids that underwent significant geological processing in the early solar system. Parent bodies of iron and some stony-iron meteorites completed a geological evolution similar to that continuing on Earth - although on much smaller length- and timescales - with melting of the metal and silicates, differentiation into core, mantle, and crust, and probably extensive volcanism. Iron and stony-iron meteorites are our only available analogues to materials found in the deep interiors of Earth and other terrestrial planets. This fact has been recognized since the work of Chladni (1794), who argued that stony-iron meteorites must have originated in outer space and fallen during fireballs and that they provide our closest analogue to the material that comprises our own planet's core. This chapter deals with our current knowledge of these meteorites. How did they form? What can they tell us about the early evolution of the solar system and its solid bodies? How closely do they resemble the materials from planetary interiors? What do we know and don't we know?Iron and stony-iron meteorites constitute ˜6% of meteorite falls (Grady, 2000). Despite their scarcity among falls, iron meteorites are our only samples of ˜75 of the ˜135 asteroids from which meteorites originate ( Keil et al., 1994; Scott, 1979; Meibom and Clark, 1999; see also Chapter 1.05), suggesting that both differentiated asteroids and the geologic processes that produced them were common.Despite the highly evolved nature of iron and stony-iron meteorites, their chemistry provides important

  18. Colour Metallography of Cast Iron

    Institute of Scientific and Technical Information of China (English)

    Zhou Jiyang; Liu Jincheng

    2010-01-01

    @@ Spheroidal Graphite Cast Iron(Ⅳ) 3.7 Segregation of SG iron The non-uniform distribution of solute elements during solidification results in the micro segregation of SG iron.As for the redistribution of elements in the phases of the solidification structure,there is no intrinsic difference between SG iron and grey iron[132].

  19. Austempered Ductile Iron Machining

    Science.gov (United States)

    Pilc, Jozef; Šajgalík, Michal; Holubják, Jozef; Piešová, Marianna; Zaušková, Lucia; Babík, Ondrej; Kuždák, Viktor; Rákoci, Jozef

    2015-12-01

    This article deals with the machining of cast iron. In industrial practice, Austempered Ductile Iron began to be used relatively recently. ADI is ductile iron that has gone through austempering to get improved properties, among which we can include strength, wear resistance or noise damping. This specific material is defined also by other properties, such as high elasticity, ductility and endurance against tenigue, which are the properties, that considerably make the tooling characteristic worse.

  20. Iron and the athlete.

    Science.gov (United States)

    Suedekum, Natalie A; Dimeff, Robert J

    2005-08-01

    Iron is an important mineral necessary for many biologic pathways. Different levels of deficiency can occur in the athlete, resulting in symptoms that range from none to severe fatigue. Iron deficiency without anemia may adversely affect athletic performance. Causes of iron deficiency include poor intake, menstrual losses, gastrointestinal and genitourinary losses due to exercise-induced ischemia or organ movement, foot strike hemolysis, thermohemolysis, and sweat losses. A higher incidence of deficiency occurs in female athletes compared with males.

  1. Recalling the Iron Girls

    Institute of Scientific and Technical Information of China (English)

    1998-01-01

    The phrase "iron girl" is symbolic of an era. Widely used in the 1960s and the early 1970s, it was a term that described women who, in the spirit of sexual equality, found in themselves a physical strength that surpassed their psychologi cal expectations. With their might and power, they proved to society that women could do everything that men could. The title of "iron girl" was their pride.The well-known writer Fan Xiaoqing, was one such iron girl. She says the "iron girls" were nothing less than a quest for perfection.

  2. Iron, Meat and Health

    Directory of Open Access Journals (Sweden)

    Catherine Geissler

    2011-02-01

    Full Text Available This article is a summary of the publication “Iron and Health” by the Scientific Advisory Committee on Nutrition (SACN to the U.K. Government (2010, which reviews the dietary intake of iron and the impact of different dietary patterns on the nutritional and health status of the U.K. population. It concludes that several uncertainties make it difficult to determine dose-response relationships or to confidently characterize the risks associated with iron deficiency or excess. The publication makes several recommendations concerning iron intakes from food, including meat, and from supplements, as well as recommendations for further research.

  3. Physics of iron

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, O.

    1993-10-01

    This volume comprises papers presented at the AIRAPT Conference, June 28 to July 1993. The iron sessions at the meeting were identified as the Second Ironworkers Convention. The renewal of interest stems from advances in technologies in both diamond-anvil cell (DAC) and shock wave studies as well as from controversies arising from a lack of consensus among both experimentalists and theoreticians. These advances have produced new data on iron in the pressure-temperature regime of interest for phase diagrams and for temperatures of the core/mantle and inner-core/outer-core boundaries. Particularly interesting is the iron phase diagram inferred from DAC studies. A new phase, {beta}, with a {gamma}-{beta}-{epsilon} triple point at about 30 GPa and 1190 K, and possible sixth phase, {omega}, with an {epsilon}-{Theta}-melt triple point at about 190 GPa and 4000 K are deemed possible. The importance of the equation of state of iron in consideration of Earth`s heat budget and the origin of its magnetic field invoke the interest of theoreticians who argue on the basis of molecular dynamics and other first principles methods. While the major thrust of both meetings was on the physics of pure iron, there was notable contributions on iron alloys. Hydrogen-iron alloys, iron-sulfur liquids, and the comparability to rhenium in phase diagram studies are discussed. The knowledge of the physical properties of iron were increased by several contributions.

  4. Iron overload and immunity

    Institute of Scientific and Technical Information of China (English)

    Gra(c)a Porto; Maria De Sousa

    2007-01-01

    Progress in the characterization of genes involved in the control of iron homeostasis in humans and in mice has improved the definition of iron overload and of the cells affected by it. The cell involved in iron overload with the greatest effect on immunity is the macrophage.Intriguing evidence has emerged, however, in the last 12 years indicating that parenchymal iron overload is linked to genes classically associated with the immune system. This review offers an update of the genes and proteins relevant to iron metabolism expressed in cells of the innate immune system, and addresses the question of how this system is affected in clinical situations of iron overload. The relationship between iron and the major cells of adaptive immunity, the T lymphocytes,will also be reviewed. Most studies addressing this last question in humans were performed in the clinical model of Hereditary Hemochromatosis. Data will also be reviewed demonstrating how the disruption of molecules essentially involved in adaptive immune responses result in the spontaneous development of iron overload and how they act as modifiers of iron overload.

  5. Benefits and harms of iron supplementation in iron-deficient and iron-sufficient children.

    Science.gov (United States)

    Domellöf, Magnus

    2010-01-01

    Due to high iron requirements, young children are at risk for iron deficiency anemia. Iron supplements are therefore often recommended, especially since iron deficiency anemia in children is associated with poor neurodevelopment. However, in contrast to most other nutrients, excess iron cannot be excreted by the human body and it has recently been suggested that excessive iron supplementation of young children may have adverse effects on growth, risk of infections, and even on cognitive development. Recent studies support that iron supplements are beneficial in iron-deficient children but there is a risk of adverse effects in those who are iron replete. In populations with a low prevalence of iron deficiency, general supplementation should therefore be avoided. Iron-fortified foods can still be generally recommended since they seem to be safer than medicinal iron supplements, but the level of iron fortification should be limited. General iron supplementation is recommended in areas with a high prevalence of iron deficiency, with the exception of malarious areas where a cautious supplementation approach needs to be adopted, based either on screening or a combination of iron supplements and infection control measures. More studies are urgently needed to better determine the risks and benefits of iron supplementation and iron-fortified foods given to iron-deficient and iron-sufficient children.

  6. N-Heterocyclic Carbene (NHC) Binuclear Gold Complexes Catalyzed Aminoarylation of Olefins%氮杂环卡宾双核金络合物催化的胺芳基化反应

    Institute of Scientific and Technical Information of China (English)

    张睿; 徐琴; 施敏

    2012-01-01

    N-Heterocyclic carbene(NHC) binuclear gold complexes and mononuclear gold complex have been successfully prepared from 1,1’-binaphthalenyl-2,2’-diamine(BINAM) in good yields.Their structures have been unambiguously determined by spectroscopic data and X-ray diffraction.On the basis of X-ray diffraction,a weak interaction between Au-Au has been identified in the N-heterocyclic carbene(NHC) binuclear gold complex 4b,in which the distance of Au(I)-Au(I) is 4.190.We also found that NHC-binuclear gold complex 4b is a more effective catalyst than that of NHC-mononuclear gold complex in the aminoarylation of olefins under identical conditions.Based on these experimental data,the improved yield of aminoarylation is possibly attributed to the weak Au(I)-Au(I) interaction in the N-heterocyclic carbene(NHC) binuclear gold complex 4b.A plausible reaction mechanism has been proposed on the basis of previous literature.The reaction procedure is quite simple.When NHC-gold(I) catalyst 4b(3 mol%,3.0 μmol) was dissolved in solvent(2.0 mL) in a flame-dried Schlenk tube equipped with a septum cap and stirring bar,the additive AgSbF6(6.0 μmol) was added under argon,and then the mixture was stirred under argon at room temperature for 10 min.Alkylamine(0.1 mmol),arylboronic acid(0.2 mmol),and selectfluor(0.2 mmol) were added,and then the reaction mixture was stirred at 60 ℃ for 12 h.The crude product was concentrated under reduced pressure,and purified by flash chromatography on silica gel(eluent: EtOAc/petroleum ether=1/16) to yield the pure corresponding product.Recently,a number of bis(gold) vinyl species have been isolated from homogeneous gold catalysis and have been identified as the key intermediate in the catalytic process.Meanwhile,binuclear gold complexes have been also realized as the key species in the homogeneous gold catalysis recently.In this paper,we first disclosed that the N

  7. [Iron deficiency and digestive disorders].

    Science.gov (United States)

    Cozon, G J N

    2014-11-01

    Iron deficiency anemia still remains problematic worldwide. Iron deficiency without anemia is often undiagnosed. We reviewed, in this study, symptoms and syndromes associated with iron deficiency with or without anemia: fatigue, cognitive functions, restless legs syndrome, hair loss, and chronic heart failure. Iron is absorbed through the digestive tract. Hepcidin and ferroportin are the main proteins of iron regulation. Pathogenic micro-organisms or intestinal dysbiosis are suspected to influence iron absorption.

  8. Theoretical and experimental spectroscopic studies of the first highly luminescent binuclear hydrocinnamate of Eu(III), Tb(III) and Gd(III) with bidentate 2,2'-bipyridine ligand

    Energy Technology Data Exchange (ETDEWEB)

    Marques, Lippy F.; Correa, Charlane C.; Garcia, Humberto C. [Departamento de Química-ICE, Universidade Federal de Juiz de Fora, Juiz de Fora-MG 36036-330 (Brazil); Martins Francisco, Thiago [Departamento de Física-ICEx, Universidade Federal de Minas Gerais, Pampulha, Belo Horizonte-MG 30123-970 (Brazil); Ribeiro, Sidney J.L. [Instituto de Química, Universidade Estadual Paulista Júlio de Mesquita Filho-UNESP, CP 355, Araraquara-SP 14801-970 (Brazil); Dutra, José Diogo L.; Freire, Ricardo O. [Pople Computational Chemistry Laboratory, Departamento de Química, Universidade Federal de Sergipe, São Cristóvão-SE 49100-000 (Brazil); Machado, Flávia C., E-mail: flavia.machado@ufjf.edu.br [Departamento de Química-ICE, Universidade Federal de Juiz de Fora, Juiz de Fora-MG 36036-330 (Brazil)

    2014-04-15

    In this paper, the synthesis of three new binuclear lanthanide (III) complexes [Ln{sub 2}(cin){sub 6}(bpy){sub 2}] (Ln=Eu (1), Tb (2), Gd (3), cin=hydrocinnamate anion; bpy=2,2'-bipyridine), and their complete characterization, including single crystal X-ray diffraction, FTIR spectroscopy and thermal analysis (TGA/DTA) are reported. In especial, photophysical properties of Eu(III) complex have been studied in detail via both theoretical and experimental approaches. Crystal structures of 1–3 reveal that all compounds are isostructural and that each lanthanide ion is nine-coordinated by oxygen and nitrogen atoms in an overall distorted tricapped trigonal-prismatic geometry. Eu(III) complex structure was also calculated using the Sparkle model for lanthanide complexes and the intensity parameters (Ω{sub 2}, Ω{sub 4}, and Ω{sub 6}), calculated from the experimental data and from Sparkle/PM3 model. The theoretical emission quantum efficiencies obtained for Sparkle/PM3 structures are in excellent agreement with the experimental values, clearly attesting to the efficacy of the theoretical models. The theoretical procedure applied here shows that the europium binuclear compound displays a quantum yield about 65% suggesting that the system can be excellent for the development of efficient luminescent devices. Highlights: • First binuclear Ln{sup 3+}-hydrocinnamate have been synthesized and characterized. • Eu{sup 3+}, Tb{sup 3+} and Gd{sup 3+} complexes photoluminescence properties were investigated. • Theoretical approaches for Eu{sup 3+} complex luminescence has been performed. • An energy level diagram is used to establish the ligand-to-metal energy transfer. • 65% Quantum yield suggests an excellent system for luminescent devices.

  9. Structural, molecular orbital and optical characterizations of binuclear mixed ligand copper (II) complex of phthalate with N,N,N',N'-tetramethylethylenediamine and its applications.

    Science.gov (United States)

    Taha, A; Farag, A A M; Ammar, A H; Ahmed, H M

    2014-09-15

    A new binuclear mixed ligand complex, [Cu2(Phth)(Me4en)2(H2O)2(NO3)2]·H2O (where, Phth=phthalate, and (Me4en)=N,N,N',N'tetramethylethylenediamine) was synthesized and characterized using analytical, spectral, magnetic, molar conductance, thermal gravimetric analysis (TGA), X-ray diffraction (XRD) and transmission electron microscope (TEM) measurements. The XRD data of Cu(II)-complex was analyzed on the basis of Williamson-Hall (W-H) and compared with TEM results. The results indicate that the complex is well crystalline and correspond to hexagonal crystal structure. Analysis of the absorption coefficient near the absorption edge reveals that the optical band gaps are indirect allowed transition with values of 1.17 and 1.78 eV. The d-d absorption bands of the complex (dissolved in various solvents) exhibit a color changes (solvatochromic). Specific and non-specific interactions of solvent molecules with the complex were investigated using Multiple Linear Regression Analysis (MLRA). Transient photocurrent characteristics of Cu(II)-complex/n-Si heterojunctions indicate that photocurrent under illumination increase with increasing of light intensity and explained by continuous distribution of traps. Structural parameters of the free ligands and their Cu(II)-complex were calculated on the basis of semi-empirical PM3 level and compared with the experimental data. The present copper (II) complex was screened for its antimicrobial activity against some Gram-positive and Gram-negative bacteria and fungus strain.

  10. A binuclear complex constituted by diethyldithiocarbamate and copper(I) functions as a proteasome activity inhibitor in pancreatic cancer cultures and xenografts.

    Science.gov (United States)

    Han, Jinbin; Liu, Luming; Yue, Xiaoqiang; Chang, Jinjia; Shi, Weidong; Hua, Yongqiang

    2013-12-15

    It is a therapeutic strategy for cancers including pancreatic to inhibit proteasome activity. Disulfiram (DSF) may bind copper (Cu) to form a DSF-Cu complex. DSF-Cu is capable of inducing apoptosis in cancer cells by inhibiting proteasome activity. DSF is rapidly converted to diethyldithiocarbamate (DDTC) within bodies. Copper(II) absorbed by bodies is reduced to copper(I) when it enters cells. We found that DDTC and copper(I) could form a binuclear complex which might be entitled DDTC-Cu(I), and it had been synthesized by us in the laboratory. This study is to investigate the anticancer potential of this complex on pancreatic cancer and the possible mechanism. Pancreatic cancer cell lines, SW1990, PANC-1 and BXPC-3 were used for in vitro assays. Female athymic nude mice grown SW1990 xenografts were used as animal models. Cell counting kit-8 (cck-8) assay and flow cytometry were used for analyzing apoptosis in cells. A 20S proteasome assay kit was used in proteasome activity analysis. Western blot (WB) and immunohistochemistry (IHC) and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assays were used in tumor sample analysis. The results suggest that DDTC-Cu(I) inhibit pancreatic cancer cell proliferation and proteasome activity in vitro and in vivo. Accumulation of ubiquitinated proteins, and increased p27 as well as decreased NF-κB expression were detected in tumor tissues of DDTC-Cu(I)-treated group. Our data indicates that DDTC-Cu(I) is an effective proteasome activity inhibitor with the potential to be explored as a drug for pancreatic cancer.

  11. Synthesis, spectroscopic studies, molecular modeling and antimicrobial activity of binuclear Co(II) and Cu(II) complexes of 4,6-diacetylresorcinol

    Science.gov (United States)

    Shebl, Magdy; Khalil, Saied M. E.; Taha, A.; Mahdi, M. A. N.

    2013-09-01

    Reactions of 4,6-diacetylresorcinol with different cobalt(II) and copper(II) salts viz., OAc-, Cl-, NO3- and SO42-, yielded a new series of binuclear metal complexes. Reactions of the ligand with these metal ions in the presence of a secondary ligand (L‧) [O,O-donor; acetylacetone, N,O-donor; 8-hydroxyquinoline or N,N-donor; 1,10-phenanthroline and N,N,N‧,N‧-tetramethylethylenediamine] in 1:2:2 (L:M:L‧) molar ratio yielded mixed-ligand complexes with different molar ratios. The metal complexes were characterized by elemental and thermal analyses, IR, electronic, ESR and mass spectra as well as conductivity and magnetic susceptibility measurements. The analytical and spectroscopic data suggested that the H2L ligand behaves as a neutral, monobasic or dibasic tetradentate ligand, depending on the type of the anion and secondary ligand used, through the two phenolic and two carbonyl groups. Electronic spectra, magnetic and conductivity measurements showed that all complexes are octahedral with non-electrolytic nature. The profile of ESR spectra of copper(II) complexes suggested the octahedral geometry and the spin Hamiltonian parameters of the complexes were calculated and discussed. Molecular orbital calculations were performed for metal complexes using Hyperchem 7.52 program on the bases of PM3 level and the results correlated with the experimental data. The free ligand and some of its metal complexes showed antimicrobial activity towards some of Gram-positive and Gram-negative bacteria, yeast (Candida albicans) and fungus (Aspergillus fumigatus).

  12. Structural, molecular orbital and optical characterizations of binuclear mixed ligand copper (II) complex of phthalate with N,N,N‧,N‧-tetramethylethylenediamine and its applications

    Science.gov (United States)

    Taha, A.; Farag, A. A. M.; Ammar, A. H.; Ahmed, H. M.

    2014-09-01

    A new binuclear mixed ligand complex, [Cu2(Phth)(Me4en)2(H2O)2(NO3)2]·H2O (where, Phth = phthalate, and (Me4en) = N,N,N‧,N‧tetramethylethylenediamine) was synthesized and characterized using analytical, spectral, magnetic, molar conductance, thermal gravimetric analysis (TGA), X-ray diffraction (XRD) and transmission electron microscope (TEM) measurements. The XRD data of Cu(II)-complex was analyzed on the basis of Williamson-Hall (W-H) and compared with TEM results. The results indicate that the complex is well crystalline and correspond to hexagonal crystal structure. Analysis of the absorption coefficient near the absorption edge reveals that the optical band gaps are indirect allowed transition with values of 1.17 and 1.78 eV. The d-d absorption bands of the complex (dissolved in various solvents) exhibit a color changes (solvatochromic). Specific and non-specific interactions of solvent molecules with the complex were investigated using Multiple Linear Regression Analysis (MLRA). Transient photocurrent characteristics of Cu(II)-complex/n-Si heterojunctions indicate that photocurrent under illumination increase with increasing of light intensity and explained by continuous distribution of traps. Structural parameters of the free ligands and their Cu(II) - complex were calculated on the basis of semi-empirical PM3 level and compared with the experimental data. The present copper (II) complex was screened for its antimicrobial activity against some Gram-positive and Gram-negative bacteria and fungus strain.

  13. Mixed-ligand binuclear copper(II) complex of 5-methylsalicylaldehyde and 2,2'-bipyridyl: Synthesis, crystal structure, DNA binding and nuclease activity

    Indian Academy of Sciences (India)

    Perumal Gurumoorthy; Jayaram Ravichandran; Aziz Kalilur Rahiman

    2014-05-01

    A new mixed-ligand binuclear copper(II) complex [Cu(MS)(bpy)]2.(ClO4)2, built of 5-methylsalicylaldehyde and 2,2'-bipyridyl has been synthesized and characterized by using elemental analysis, IR and UV-Vis spectroscopy. Crystal structure of the complex shows that copper(II) ion lies in a square pyramidal coordination environment. The structure consists of two symmetrical half units in which the copper(II) ion of one half unit connected with the phenolate oxygen atom of other half unit along with one perchlorate anion in the crystal lattice as free molecule. Presence of uncoordinated perchlorate anion was also confirmed by IR spectroscopy. Absorption spectroscopy exhibits d-d transition at 628 nm, which further supports the square pyramidal geometry around the copper(II) ions. EPR spectrum of the copper(II) complex at room temperature shows a broad signal without any splitting pattern at ∥ = 2.26, ⊥ = 2.03 and the magnetic moment (eff = 1.31 BM) obtained at room temperature indicate an antiferromagnetic interaction between the two copper(II) ions through phenoxide-bridge. Binding studies reveal that the complex possesses good binding propensity (b = 5.2 ± 1.7 × 104 M-1) and bind to nitrogenous bases of DNA through intercalation. Nuclease activity of the complex with pBR322 DNA shows that the effect of hydrolytic cleavage is dose-dependent and the oxidative cleavage indicates the involvement of hydroxyl radical and singlet-oxygen as reactive oxygen species.

  14. Embryonic neural inducing factor churchill is not a DNA-binding zinc finger protein: solution structure reveals a solvent-exposed beta-sheet and zinc binuclear cluster.

    Science.gov (United States)

    Lee, Brian M; Buck-Koehntop, Bethany A; Martinez-Yamout, Maria A; Dyson, H Jane; Wright, Peter E

    2007-08-31

    Churchill is a zinc-containing protein that is involved in neural induction during embryogenesis. At the time of its discovery, it was thought on the basis of sequence alignment to contain two zinc fingers of the C4 type. Further, binding of an N-terminal GST-Churchill fusion protein to a particular DNA sequence was demonstrated by immunoprecipitation selection assay, suggesting that Churchill may function as a transcriptional regulator by sequence-specific DNA binding. We show by NMR solution structure determination that, far from containing canonical C4 zinc fingers, the protein contains three bound zinc ions in novel coordination sites, including an unusual binuclear zinc cluster. The secondary structure of Churchill is also unusual, consisting of a highly solvent-exposed single-layer beta-sheet. Hydrogen-deuterium exchange and backbone relaxation measurements reveal that Churchill is unusually dynamic on a number of time scales, with the exception of regions surrounding the zinc coordinating sites, which serve to stabilize the otherwise unstructured N terminus and the single-layer beta-sheet. No binding of Churchill to the previously identified DNA sequence could be detected, and extensive searches using DNA sequence selection techniques could find no other DNA sequence that was bound by Churchill. Since the N-terminal amino acids of Churchill form part of the zinc-binding motif, the addition of a fusion protein at the N terminus causes loss of zinc and unfolding of Churchill. This observation most likely explains the published DNA-binding results, which would arise due to non-specific interaction of the unfolded protein in the immunoprecipitation selection assay. Since Churchill does not appear to bind DNA, we suggest that it may function in embryogenesis as a protein-interaction factor.

  15. Synthesis, characterization, biological evaluation and docking studies of macrocyclic binuclear manganese(II) complexes containing 3,5-dinitrobenzoyl pendant arms.

    Science.gov (United States)

    Arthi, P; Shobana, S; Srinivasan, P; Mitu, L; Kalilur Rahiman, A

    2015-05-15

    A series of bis(phenoxo) bridged binuclear manganese(II) complexes of the type [Mn2L(1-3)](ClO4)2 (1-3) containing 3,5-dinitrobenzoyl pendant-arms have been synthesized by cyclocondensation of 2,6-diformyl-4-R-phenols (where R=CH3, C(CH3)3 or Br) with 2,2'-3,5-dinitrobenzoyliminodi(ethylamine) trihydrochloride in the presence of manganese(II) perchlorate. The IR spectra of complexes indicate the presence of uncoordinated perchlorate anions. The UV-Vis spectra of complexes suggest the distorted octahedral geometry around manganese(II) nuclei. The EPR spectra of Mn(II) complexes show a broad signal with g value 2.03-2.04, which is characteristic for octahedral high spin Mn(2+) complex. The observed room temperature magnetic moment values of the Mn(II) complexes (5.60-5.62B.M.) are less than the normal value (5.92B.M.), indicating weak antiferromagnetic coupling interaction between the two metal ions. Electrochemical studies of the complexes show two distinct quasi-reversible one electron transfer processes in the cathodic (E(1)pc=-0.73 to -0.76V, E(2)pc=-1.30 to -1.36V), and anodic (E(1)pa=1.02-1.11V, E(2)pa=1.32-1.79V) potential regions. Antibacterial efficacy of complexes have been screened against four Gram (-ve) and two Gram (+ve) bacterial strains. The DNA interaction studies suggest that these complexes bind with CT-DNA by intercalation, giving the binding affinity in the order 1>2>3. All the complexes display significant cleavage activity against circular plasmid pBR322 DNA. Docking simulation was performed to insert complexes into the crystal structure of EGFR tyrosine kinase and B-DNA at active site to determine the probable binding mode.

  16. Thin Wall Iron Castings

    Energy Technology Data Exchange (ETDEWEB)

    J.F. Cuttino; D.M. Stefanescu; T.S. Piwonka

    2001-10-31

    Results of an investigation made to develop methods of making iron castings having wall thicknesses as small as 2.5 mm in green sand molds are presented. It was found that thin wall ductile and compacted graphite iron castings can be made and have properties consistent with heavier castings. Green sand molding variables that affect casting dimensions were also identified.

  17. Total iron binding capacity

    Science.gov (United States)

    ... the intestines not properly absorbing vitamin B12 ( pernicious anemia ) Sickle cell anemia Risks There is very little risk involved with ... test Hemoglobin Hemolytic anemia Iron deficiency anemia Pernicious anemia Serum iron test Sickle cell anemia Review Date 2/11/2016 Updated by: ...

  18. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... Blood Tests Blood Transfusion Restless Legs Syndrome Send a link to NHLBI to someone by E-MAIL | ... Iron-Deficiency Anemia? Español Iron-deficiency anemia is a common, easily treated condition that occurs if you ...

  19. Iron deficiency in childhood

    NARCIS (Netherlands)

    Uijterschout, L.

    2015-01-01

    Iron deficiency (ID) is the most common micronutrient deficiency in the world. Iron is involved in oxygen transport, energy metabolism, immune response, and plays an important role in brain development. In infancy, ID is associated with adverse effects on cognitive, motor, and behavioral development

  20. Colour Metallography of Cast Iron

    Institute of Scientific and Technical Information of China (English)

    Zhou Jiyang; Liu Jincheng

    2011-01-01

    White Cast Iron (Ⅰ) White cast iron or ‘white iron' refers to the type of cast iron in which all of the carbon exists as carbide;there is no graphite in the as-cast structure and the fractured surface shows a white colour.White cast iron can be divided in three classes:· Normal white cast iron — this iron contains only C,Si,Mn,P and S,with no other alloying elements.· Low-alloy white cast iron — the total mass fraction of alloying elements is less than 5%.

  1. Iron replacement therapy

    DEFF Research Database (Denmark)

    Nielsen, Ole Haagen; Coskun, Mehmet; Weiss, Günter

    2016-01-01

    PURPOSE OF REVIEW: Approximately, one-third of the world's population suffers from anemia, and at least half of these cases are because of iron deficiency. With the introduction of new intravenous iron preparations over the last decade, uncertainty has arisen when these compounds should...... be administered and under which circumstances oral therapy is still an appropriate and effective treatment. RECENT FINDINGS: Numerous guidelines are available, but none go into detail about therapeutic start and end points or how iron-deficiency anemia should be best treated depending on the underlying cause...... of iron deficiency or in regard to concomitant underlying or additional diseases. SUMMARY: The study points to major issues to be considered in revisions of future guidelines for the true optimal iron replacement therapy, including how to assess the need for treatment, when to start and when to stop...

  2. Iron(III) complexes of 2-(1H-benzo[d]imidazol-2-yl)phenol and acetate or nitrate as catalysts for epoxidation of olefins with hydrogen peroxide

    Science.gov (United States)

    Dutta, Amit Kumar; Samanta, Suvendu; Dutta, Supriya; Lucas, C. Robert; Dawe, Louise N.; Biswas, Papu; Adhikary, Bibhutosh

    2016-07-01

    Cheap and environmentally friendly Fe(III) catalysts [Fe(L)2(CH3COO)] (1) and [Fe(L)2(NO3)]·2CH3OH (2) where HL = 2-(1H-benzo[d]imidazol-2-yl)phenol for epoxidation of olefins have been developed. The catalysts have been characterized by elemental analyses, IR, UV-Vis spectroscopy and by X-ray crystallography. The X-ray structures reveal mononuclear compounds having a bidentate acetate or nitrate in 1 and 2, respectively. Catalytic epoxidations of styrene and cyclohexene have been carried out homogeneously by using 30% aqueous hydrogen peroxide in acetonitrile in the presence of catalytic amounts of 1 or 2. Yields of the respective epoxides were fair (1) to good (2) and selectivities were good in all cases although 2 produced two to three times the yield, depending on the substrate, than 1 and higher selectivity as well. A hypothesis for these differences in catalytic efficacy between 1 and 2 that is consistent with mechanistic details of related enzymatic and biomimetic model systems is proposed. Herein we report [Fe(L)2(NO3)]·2CH3OH (2) as the first structurally characterized non-heme iron epoxidation catalyst with a bidentate nitrate ligand.

  3. A time-resolved iron-specific X-ray absorption experiment yields no evidence for an Fe2+ --> Fe3+ transition during QA- --> QB electron transfer in the photosynthetic reaction center.

    Science.gov (United States)

    Hermes, Sabine; Bremm, Oliver; Garczarek, Florian; Derrien, Valerie; Liebisch, Peter; Loja, Paola; Sebban, Pierre; Gerwert, Klaus; Haumann, Michael

    2006-01-17

    Previous time-resolved FTIR measurements suggested the involvement of an intermediary component in the electron transfer step Q(A)- --> Q(B) in the photosynthetic reaction center (RC) from Rhodobacter sphaeroides [Remy and Gerwert (2003) Nat. Struct. Biol. 10, 637]. By a kinetic X-ray absorption experiment at the Fe K-edge we investigated whether oxidation occurs at the ferric non-heme iron located between the two quinones. In isolated reaction centers with a high content of functional Q(B), at a time resolution of 30 micros and at room temperature, no evidence for transient oxidation of Fe was obtained. However, small X-ray transients occurred, in a similar micro- to millisecond time range as in the IR experiments, which may point to changes in the Fe ligand environment due to the charges on Q(A)- and Q(B)-. In addition, VIS measurements agree with the IR data and do not exclude an intermediate in the Q(A)- --> Q(B) transition.

  4. Iron and the endurance athlete.

    Science.gov (United States)

    Hinton, Pamela S

    2014-09-01

    Iron is a trace mineral that is highly significant to endurance athletes. Iron is critical to optimal athletic performance because of its role in energy metabolism, oxygen transport, and acid-base balance. Endurance athletes are at increased risk for suboptimal iron status, with potential negative consequences on performance, because of the combination of increased iron needs and inadequate dietary intake. This review paper summarizes the role of iron in maximal and submaximal exercise and describes the effects of iron deficiency on exercise performance. Mechanisms that explain the increased risk of iron deficiency in endurance athletes, including exercise-associated inflammation and hepcidin release on iron sequestration, are described. Information on screening athletes for iron deficiency is presented, and suggestions to increase iron intake through diet modification or supplemental iron are provided.

  5. From Iron Bowl to Iron Stomach

    Institute of Scientific and Technical Information of China (English)

    MICHAEL; L.; O’NEAL

    2009-01-01

    A few decades ago, "Iron Bowl" referred to not having to go hungry in China if you were employed by the Agovernment. The government gave you a job that secured the filling of one’s rice bowl. This concept and practice did create loyalty, as the times were hard. China has moved far past those times to become the

  6. 21 CFR 310.518 - Drug products containing iron or iron salts.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 5 2010-04-01 2010-04-01 false Drug products containing iron or iron salts. 310... Drug products containing iron or iron salts. Drug products containing elemental iron or iron salts as...) that contains iron or iron salts for use as an iron source shall bear the following statement:...

  7. HYSCORE Analysis of the Effects of Substrates on Coordination of Water to the Active Site Iron in Tyrosine Hydroxylase.

    Science.gov (United States)

    McCracken, John; Eser, Bekir E; Mannikko, Donald; Krzyaniak, Matthew D; Fitzpatrick, Paul F

    2015-06-23

    Tyrosine hydroxylase is a mononuclear non-heme iron monooxygenase found in the central nervous system that catalyzes the hydroxylation of tyrosine to yield L-3,4-dihydroxyphenylalanine, the rate-limiting step in the biosynthesis of catecholamine neurotransmitters. Catalysis requires the binding of tyrosine, a tetrahydropterin, and O₂ at an active site that consists of a ferrous ion coordinated facially by the side chains of two histidines and a glutamate. We used nitric oxide as a surrogate for O₂ to poise the active site iron in an S = ³/₂ {FeNO}⁷ form that is amenable to electron paramagnetic resonance (EPR) spectroscopy. The pulsed EPR method of hyperfine sublevel correlation (HYSCORE) spectroscopy was then used to probe the ligands at the remaining labile coordination sites on iron. For the complex formed by the addition of tyrosine and nitric oxide, TyrH/NO/Tyr, orientation-selective HYSCORE studies provided evidence of the coordination of one H₂O molecule characterized by proton isotropic hyperfine couplings (A(iso) = 0.0 ± 0.3 MHz) and dipolar couplings (T = 4.4 and 4.5 ± 0.2 MHz). These data show complex HYSCORE cross peak contours that required the addition of a third coupled proton, characterized by an A(iso) of 2.0 MHz and a T of 3.8 MHz, to the analysis. This proton hyperfine coupling differed from those measured previously for H₂O bound to {FeNO}⁷ model complexes and was assigned to a hydroxide ligand. For the complex formed by the addition of tyrosine, 6-methyltetrahydropterin, and NO, TyrH/NO/Tyr/6-MPH₄, the HYSCORE cross peaks attributed to H₂O and OH⁻ for the TyrH/NO/Tyr complex were replaced by a cross peak due to a single proton characterized by an A(iso) of 0.0 MHz and a dipolar coupling (T = 3.8 MHz). This interaction was assigned to the N₅ proton of the reduced pterin.

  8. Colour Metallography of Cast Iron

    Institute of Scientific and Technical Information of China (English)

    Zhou Jiyang; Liu Jincheng

    2009-01-01

    @@ This book consists of five sections:Chapter 1 Introduction,Chapter 2 Grey Iron,Chapter 3 Ductile Iron,Chapter 4Vermicular Cast Iron,and Chapter 5 White Cast Iron. CHINA FOUNDRY publishs this book in several parts serially,starting from the first issue of 2009.

  9. Colour Metallography of Cast Iron

    Institute of Scientific and Technical Information of China (English)

    Zhou Jiyang; Ph.D Liu Jincheng

    2010-01-01

    @@ Note: This book consists of five sections: Chapter 1 Introduction, Chapter 2 Grey Iron, Chapter 3 Spheroidal Graphite Cast Iron, Chapter 4 Vermicular Cast Iron, and Chapter 5 White Cast Iron. CHINA FOUNDRY publishes this book in several parts serially, starting from the first issue of 2009.

  10. In situ treatment of arsenic contaminated groundwater by aquifer iron coating: Experimental study

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Xianjun, E-mail: xjxie@cug.edu.cn [State Key Laboratory of Biogeology and Environmental Geology, School of Environmental Studies, China University of Geosciences, 430074 Wuhan (China); Wang, Yanxin, E-mail: yx.wang@cug.edu.cn [State Key Laboratory of Biogeology and Environmental Geology, School of Environmental Studies, China University of Geosciences, 430074 Wuhan (China); Pi, Kunfu [State Key Laboratory of Biogeology and Environmental Geology, School of Environmental Studies, China University of Geosciences, 430074 Wuhan (China); Liu, Chongxuan [State Key Laboratory of Biogeology and Environmental Geology, School of Environmental Studies, China University of Geosciences, 430074 Wuhan (China); Pacific Northwest National Laboratory, Richland, WA 99354 (United States); Li, Junxia; Liu, Yaqing; Wang, Zhiqiang; Duan, Mengyu [State Key Laboratory of Biogeology and Environmental Geology, School of Environmental Studies, China University of Geosciences, 430074 Wuhan (China)

    2015-09-15

    In situ arsenic removal from groundwater by an aquifer iron coating method has great potential to be a cost effective and simple groundwater remediation technology, especially in rural and remote areas where groundwater is used as the main water source for drinking. The in situ arsenic removal technology was first optimized by simulating arsenic removal in various quartz sand columns under anoxic conditions. The effectiveness was then evaluated in an actual high-arsenic groundwater environment. The arsenic removal mechanism by the coated iron oxide/hydroxide was investigated under different conditions using scanning electron microscopy (SEM)/X-ray absorption spectroscopy, electron probe microanalysis, and Fourier transformation infrared spectroscopy. Aquifer iron coating method was developed via a 4-step alternating injection of oxidant, iron salt and oxygen-free water. A continuous injection of 5.0 mmol/L FeSO{sub 4} and 2.5 mmol/L NaClO for 96 h can form a uniform goethite coating on the surface of quartz sand without causing clogging. At a flow rate of 7.2 mL/min of the injection reagents, arsenic (as Na{sub 2}HAsO{sub 4}) and tracer fluorescein sodium to pass through the iron-coated quartz sand column were approximately at 126 and 7 column pore volumes, respectively. The retardation factor of arsenic was 23.0, and the adsorption capacity was 0.11 mol As per mol Fe. In situ arsenic removal from groundwater in an aquifer was achieved by simultaneous injections of As(V) and Fe(II) reagents. Arsenic fixation resulted from a process of adsorption/co-precipitation with fine goethite particles by way of bidentate binuclear complexes. Therefore, the study results indicate that the high arsenic removal efficiency of the in situ aquifer iron coating technology likely resulted from the expanded specific surface area of the small goethite particles, which enhanced arsenic sorption capability and/or from co-precipitation of arsenic on the surface of goethite particles

  11. Sorptive Uptake Studies of an Aryl-Arsenical with Iron Oxide Composites on an Activated Carbon Support

    Directory of Open Access Journals (Sweden)

    Jae H. Kwon

    2014-03-01

    Full Text Available Sorption uptake kinetics and equilibrium studies for 4-hydroxy-3-nitrobenzene arsonic acid (roxarsone was evaluated with synthetic magnetite (Mag-P, commercial magnetite (Mag-C, magnetite 10%, 19%, and 32% composite material (CM-10, -19, -32 that contains granular activated carbon (GAC, and synthetic goethite at pH 7.00 in water at 21 °C for 24 h. GAC showed the highest sorptive removal of roxarsone and the relative uptake for each sorbent material with roxarsone are listed in descending order as follows: GAC (471 mg/g > goethite (418 mg/g > CM-10 (377 mg/g CM-19 (254 mg/g > CM-32 (227 mg/g > Mag-P (132 mg/g > Mag-C (29.5 mg/g. The As (V moiety of roxarsone is adsorbed onto the surface of the iron oxide/oxyhydrate and is inferred as inner-sphere surface complexes; monodentate-mononuclear, bidentate-mononuclear, and bidentate-binuclear depending on the protolytic speciation of roxarsone. The phenyl ring of roxarsone provides the primary driving force for the sorptive interaction with the graphene surface of GAC and its composites. Thus, magnetite composites are proposed as multi-purpose adsorbents for the co-removal of inorganic and organic arsenicals due to the presence of graphenic and iron oxide active adsorption sites.

  12. Iron in diet

    Science.gov (United States)

    ... rich in vitamin C ( such as citrus, strawberries, tomatoes, and potatoes) also increase iron absorption. Cooking foods ... Vomiting Headache Weight loss Shortness of breath Grayish color to the skin

  13. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... chest pain, and other symptoms. Severe iron-deficiency anemia can lead to heart problems, infections, problems with growth and development in children, and other complications. Infants and young children and ...

  14. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... Events Spokespeople Email Alerts E-Newsletters About NHLBI Organization NHLBI Director Budget, Planning, & Legislative Advisory Committees Jobs ... food. Overview Iron-deficiency anemia is a common type of anemia . The term "anemia" usually refers to ...

  15. Iron-Deficiency Anemia

    Medline Plus

    Full Text Available ... CAUSES WHO IS AT RISK SIGNS & SYMPTOMS DIAGNOSIS TREATMENTS PREVENTION LIVING WITH CLINICAL TRIALS LINKS Related Topics ... Doctors usually can successfully treat iron-deficiency anemia. Treatment will depend on the cause and severity of ...

  16. Ocean iron fertilization

    Digital Repository Service at National Institute of Oceanography (India)

    Naqvi, S.W.A.; Smetacek, V.

    In 2009 and 2010, an Indo-German scientific expedition dusted the ocean with iron to stimulate the biological pump that captures atmosphereic carbon dioxide. Two onboard scientists tell the story of this controversial project. Besides raising...

  17. Ferrous Sulfate (Iron)

    Science.gov (United States)

    ... is used to treat or prevent iron-deficiency anemia, a condition that occurs when the body has ... and pharmacist what prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking or ...

  18. Iron and Your Child

    Science.gov (United States)

    ... red blood cell that carries oxygen from the lungs to the body. Iron gives hemoglobin the strength ... dried beans and peas dried fruits leafy dark green ... serving coffee or tea at mealtime — both contain tannins that reduce the ...

  19. Iron deficiency and iron deficiency anemia in women.

    Science.gov (United States)

    Coad, Jane; Pedley, Kevin

    2014-01-01

    Iron deficiency is one of the most common nutritional problems in the world and disproportionately affects women and children. Stages of iron deficiency can be characterized as mild deficiency where iron stores become depleted, marginal deficiency where the production of many iron-dependent proteins is compromised but hemoglobin levels are normal and iron deficiency anemia where synthesis of hemoglobin is decreased and oxygen transport to the tissues is reduced. Iron deficiency anemia is usually assessed by measuring hemoglobin levels but this approach lacks both specificity and sensitivity. Failure to identify and treat earlier stages of iron deficiency is concerning given the neurocognitive implications of iron deficiency without anemia. Most of the daily iron requirement is derived from recycling of senescent erythrocytes by macrophages; only 5-10 % comes from the diet. Iron absorption is affected by inhibitors and enhancers of iron absorption and by the physiological state. Inflammatory conditions, including obesity, can result in iron being retained in the enterocytes and macrophages causing hypoferremia as a strategic defense mechanism to restrict iron availability to pathogens. Premenopausal women usually have low iron status because of iron loss in menstrual blood. Conditions which further increase iron loss, compromise absorption or increase demand, such as frequent blood donation, gastrointestinal lesions, athletic activity and pregnancy, can exceed the capacity of the gastrointestinal tract to upregulate iron absorption. Women of reproductive age are at particularly high risk of iron deficiency and its consequences however there is a controversial argument that evolutionary pressures have resulted in an iron deficient phenotype which protects against infection.

  20. Colour Metallography of Cast Iron

    Institute of Scientific and Technical Information of China (English)

    Zhou Jiyang; Liu Jincheng

    2011-01-01

    @@ Vermicular graphite cast iron(VG iron for short in the following sections)is a type of cast iron in which the graphite is intermediate in shape between flake and spheroidal.Compared with the normal flake graphite in grey iron, the graphite in VG iron is shorter and thicker and shows a curved, more rounded shape.Because its outer contour is exactly like a worm, hence it is called vermicular graphite.

  1. Iron-Air Rechargeable Battery

    Science.gov (United States)

    Narayan, Sri R. (Inventor); Prakash, G.K. Surya (Inventor); Kindler, Andrew (Inventor)

    2014-01-01

    Embodiments include an iron-air rechargeable battery having a composite electrode including an iron electrode and a hydrogen electrode integrated therewith. An air electrode is spaced from the iron electrode and an electrolyte is provided in contact with the air electrode and the iron electrodes. Various additives and catalysts are disclosed with respect to the iron electrode, air electrode, and electrolyte for increasing battery efficiency and cycle life.

  2. Iron isomaltoside 1000: a new intravenous iron for treating iron deficiency in chronic kidney disease

    DEFF Research Database (Denmark)

    Wikström, Björn; Bhandari, Sunil; Barany, Peter;

    2011-01-01

    Patients with chronic kidney disease (CKD) often suffer from iron deficiency anemia necessitating treatment with intravenous iron. This study was designed to assess the safety of iron isomaltoside 1000 (Monofer) in CKD patients. The secondary objective was to assess its effect on iron deficiency...... anemia....

  3. Arsenic adsorption by iron-aluminium hydroxide coated onto macroporous supports: Insights from X-ray absorption spectroscopy and comparison with granular ferric hydroxides.

    Science.gov (United States)

    Suresh Kumar, Prashanth; Flores, Roxana Quiroga; Sjöstedt, Carin; Önnby, Linda

    2016-01-25

    This paper evaluates the arsenic adsorption characteristics of a macroporous polymer coated with coprecipitated iron-aluminium hydroxides (MHCMP). The MHCMP adsorbent-composite fits best with a pseudo-second order model for As(III) and a pseudo-first order kinetic model for As(V). The MHCMP shows a maximum adsorption capacity of 82.3 and 49.6 mg As/g adsorbent for As(III) and As(V) ions respectively, and adsorption followed the Langmuir model. Extended X-ray absorption fine structure showed that binding of As(III) ions were confirmed to take place on the iron hydroxides coated on the MHCMP, whereas for As(V) ions the binding specificity could not be attributed to one particular metal hydroxide. As(III) formed a bidentate mononuclear complex with Fe sites, whereas As(V) indicated on a bidentate binuclear complex with Al sites or monodentate with Fe sites on the adsorbent. The column experiments were run in a well water spiked with a low concentration of As(III) (100 μg/L) and a commercially available adsorbent (GEH(®)102) based on granular iron-hydroxide was used for comparison. It was found that the MHCMP was able to treat 7 times more volume of well water as compared to GEH(®)102, maintaining the threshold concentration of less than 10 μg As/L, indicating that the MHCMP is a superior adsorbent.

  4. Iron-Refractory Iron Deficiency Anemia

    OpenAIRE

    Ebru Yılmaz Keskin; İdil Yenicesu

    2015-01-01

    Demir, oksijenin taşınması, DNA sentezi ve hücre çoğalması gibi çeşitli biyolojik reaksiyonlar için vazgeçilmez olduğundan, yaşam için zorunludur. Demir metabolizması ve bu elementin düzenlenmesiyle ilgili bilgilerimiz, son yıllarda belirgin şekilde değişmiştir. Demir metabolizması ile ilgili yeni bozukluklar tanımlanmış ve demirin başka bozuklukların kofaktörü olduğu anlaşılmaya başlamıştır. Hemokromatozis ve demir tedavisine dirençli demir eksikliği anemisi (IRIDA; “iron-refractory iron def...

  5. Synthesis, spectroscopic characterization and antimicrobial activity of binuclear metal complexes of a new asymmetrical Schiff base ligand: DNA binding affinity of copper(II) complexes.

    Science.gov (United States)

    Shebl, Magdy

    2014-01-03

    The 1:1 condensation of o-acetoacetylphenol and 1,2-diaminopropane under condition of high dilution gives the mono-condensed Schiff base, (E)-3-(1-aminopropan-2-ylimino)-1-(2-hydroxyphenyl)butan-1-one. The mono-condensed Schiff base has been used for further condensation with isatin to obtain the new asymmetrical dicompartmental Schiff base ligand, (E)-3-(2-((E)-4-(2-hydroxyphenyl)-4-oxobutan-2-ylideneamino) propylimino)indolin-2-one (H3L) with a N2O3 donor set. Reactions of the ligand with metal salts give a series of new binuclear complexes. The ligand and its metal complexes were characterized by elemental analyses, IR, (1)H and (13)C NMR, electronic, ESR and mass spectra, conductivity and magnetic susceptibility measurements as well as thermal analyses. The analytical and spectroscopic tools showed that the complexes can be formulated as: [(HL)(VO)2(SO4)(H2O)]·4H2O, [(HL)Fe2Cl4(H2O)3]·EtOH, [(HL)Fe2(ox)Cl2(H2O)3]·2H2O, [(L)M2(OAc)(H2O)m]·nH2O; M=Co, Ni or Cu, m=4, 0 and n=2, 3, [(HL)Cu2Cl]Cl·6H2O and [(L)(UO2)2(OAc)(H2O)3]·6H2O. The metal complexes exhibited octahedral geometrical arrangements except copper complexes that exhibited tetrahedral geometries and uranyl complex in which the metal ion is octa-coordinated. The Schiff base and its metal complexes were evaluated for antimicrobial activity against Gram positive bacteria (Staphylococcus aureus), Gram negative bacteria (Escherichia coli) and fungi (Candida albicans and Aspergillus flavus). The ligand and some of its complexes were found to be biologically active. The DNA-binding properties of the copper complexes (6 and 7) have been investigated by electronic absorption, fluorescence and viscosity measurements. The results obtained indicate that these complexes bind to DNA via an intercalation binding mode with an intrinsic binding constant, Kb of 1.34×10(4) and 2.5×10(4) M(-1), respectively.

  6. Synthesis, characterization, biological evaluation and docking studies of macrocyclic binuclear manganese(II) complexes containing 3,5-dinitrobenzoyl pendant arms

    Science.gov (United States)

    Arthi, P.; Shobana, S.; Srinivasan, P.; Mitu, L.; Kalilur Rahiman, A.

    2015-05-01

    A series of bis(phenoxo) bridged binuclear manganese(II) complexes of the type [Mn2L1-3](ClO4)2 (1-3) containing 3,5-dinitrobenzoyl pendant-arms have been synthesized by cyclocondensation of 2,6-diformyl-4-R-phenols (where R = sbnd CH3, sbnd C(CH3)3 or sbnd Br) with 2,2‧-3,5-dinitrobenzoyliminodi(ethylamine) trihydrochloride in the presence of manganese(II) perchlorate. The IR spectra of complexes indicate the presence of uncoordinated perchlorate anions. The UV-Vis spectra of complexes suggest the distorted octahedral geometry around manganese(II) nuclei. The EPR spectra of Mn(II) complexes show a broad signal with g value 2.03-2.04, which is characteristic for octahedral high spin Mn2+ complex. The observed room temperature magnetic moment values of the Mn(II) complexes (5.60-5.62 B.M.) are less than the normal value (5.92 B.M.), indicating weak antiferromagnetic coupling interaction between the two metal ions. Electrochemical studies of the complexes show two distinct quasi-reversible one electron transfer processes in the cathodic (E1pc = -0.73 to -0.76 V, E2pc = -1.30 to -1.36 V), and anodic (E1pa = 1.02-1.11 V, E2pa = 1.32-1.79 V) potential regions. Antibacterial efficacy of complexes have been screened against four Gram (-ve) and two Gram (+ve) bacterial strains. The DNA interaction studies suggest that these complexes bind with CT-DNA by intercalation, giving the binding affinity in the order 1 > 2 > 3. All the complexes display significant cleavage activity against circular plasmid pBR322 DNA. Docking simulation was performed to insert complexes into the crystal structure of EGFR tyrosine kinase and B-DNA at active site to determine the probable binding mode.

  7. A binuclear complex constituted by diethyldithiocarbamate and copper(I) functions as a proteasome activity inhibitor in pancreatic cancer cultures and xenografts

    Energy Technology Data Exchange (ETDEWEB)

    Han, Jinbin, E-mail: hanjinbin@gmail.com [Department of Integrative Oncology, Fudan University Shanghai Cancer Center, Shanghai 200032 (China); Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032 (China); Shanghai Clinical Center, Chinese Academy of Sciences/Xuhui Central Hospital, Shanghai 200031 (China); Liu, Luming, E-mail: llm1010@163.com [Department of Integrative Oncology, Fudan University Shanghai Cancer Center, Shanghai 200032 (China); Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032 (China); Yue, Xiaoqiang [Department of Traditional Chinese Medicine, Changhai Hospital, Second Military Medical University, Shanghai 200433 (China); Chang, Jinjia [Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032 (China); Department of Medical Oncology, Fudan University Shanghai Cancer Center, Shanghai 200032 (China); Shi, Weidong; Hua, Yongqiang [Department of Integrative Oncology, Fudan University Shanghai Cancer Center, Shanghai 200032 (China); Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032 (China)

    2013-12-15

    It is a therapeutic strategy for cancers including pancreatic to inhibit proteasome activity. Disulfiram (DSF) may bind copper (Cu) to form a DSF–Cu complex. DSF–Cu is capable of inducing apoptosis in cancer cells by inhibiting proteasome activity. DSF is rapidly converted to diethyldithiocarbamate (DDTC) within bodies. Copper(II) absorbed by bodies is reduced to copper(I) when it enters cells. We found that DDTC and copper(I) could form a binuclear complex which might be entitled DDTC–Cu(I), and it had been synthesized by us in the laboratory. This study is to investigate the anticancer potential of this complex on pancreatic cancer and the possible mechanism. Pancreatic cancer cell lines, SW1990, PANC-1 and BXPC-3 were used for in vitro assays. Female athymic nude mice grown SW1990 xenografts were used as animal models. Cell counting kit-8 (cck-8) assay and flow cytometry were used for analyzing apoptosis in cells. A 20S proteasome assay kit was used in proteasome activity analysis. Western blot (WB) and immunohistochemistry (IHC) and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assays were used in tumor sample analysis. The results suggest that DDTC–Cu(I) inhibit pancreatic cancer cell proliferation and proteasome activity in vitro and in vivo. Accumulation of ubiquitinated proteins, and increased p27 as well as decreased NF-κB expression were detected in tumor tissues of DDTC–Cu(I)-treated group. Our data indicates that DDTC–Cu(I) is an effective proteasome activity inhibitor with the potential to be explored as a drug for pancreatic cancer. - Highlights: • A new structure of DDTC–Cu(I) was reported for the first time. • DDTC–Cu(I) dissolved directly in water was for in vitro and in vivo uses. • DDTC–Cu(I) demonstrated significant anticancer effect in vitro and in vivo. • DDTC–Cu(I) is capable of inhibiting proteasome activity in vitro and in vivo.

  8. Iron Absorption in Drosophila melanogaster

    Science.gov (United States)

    Mandilaras, Konstantinos; Pathmanathan, Tharse; Missirlis, Fanis

    2013-01-01

    The way in which Drosophila melanogaster acquires iron from the diet remains poorly understood despite iron absorption being of vital significance for larval growth. To describe the process of organismal iron absorption, consideration needs to be given to cellular iron import, storage, export and how intestinal epithelial cells sense and respond to iron availability. Here we review studies on the Divalent Metal Transporter-1 homolog Malvolio (iron import), the recent discovery that Multicopper Oxidase-1 has ferroxidase activity (iron export) and the role of ferritin in the process of iron acquisition (iron storage). We also describe what is known about iron regulation in insect cells. We then draw upon knowledge from mammalian iron homeostasis to identify candidate genes in flies. Questions arise from the lack of conservation in Drosophila for key mammalian players, such as ferroportin, hepcidin and all the components of the hemochromatosis-related pathway. Drosophila and other insects also lack erythropoiesis. Thus, systemic iron regulation is likely to be conveyed by different signaling pathways and tissue requirements. The significance of regulating intestinal iron uptake is inferred from reports linking Drosophila developmental, immune, heat-shock and behavioral responses to iron sequestration. PMID:23686013

  9. Iron Absorption in Drosophila melanogaster

    Directory of Open Access Journals (Sweden)

    Fanis Missirlis

    2013-05-01

    Full Text Available The way in which Drosophila melanogaster acquires iron from the diet remains poorly understood despite iron absorption being of vital significance for larval growth. To describe the process of organismal iron absorption, consideration needs to be given to cellular iron import, storage, export and how intestinal epithelial cells sense and respond to iron availability. Here we review studies on the Divalent Metal Transporter-1 homolog Malvolio (iron import, the recent discovery that Multicopper Oxidase-1 has ferroxidase activity (iron export and the role of ferritin in the process of iron acquisition (iron storage. We also describe what is known about iron regulation in insect cells. We then draw upon knowledge from mammalian iron homeostasis to identify candidate genes in flies. Questions arise from the lack of conservation in Drosophila for key mammalian players, such as ferroportin, hepcidin and all the components of the hemochromatosis-related pathway. Drosophila and other insects also lack erythropoiesis. Thus, systemic iron regulation is likely to be conveyed by different signaling pathways and tissue requirements. The significance of regulating intestinal iron uptake is inferred from reports linking Drosophila developmental, immune, heat-shock and behavioral responses to iron sequestration.

  10. [Iron deficiency and iron deficiency anemia are global health problems].

    Science.gov (United States)

    Dahlerup, Jens; Lindgren, Stefan; Moum, Björn

    2015-03-10

    Iron deficiency and iron deficiency anemia are global health problems leading to deterioration in patients' quality of life and more serious prognosis in patients with chronic diseases. The cause of iron deficiency and anemia is usually a combination of increased loss and decreased intestinal absorption and delivery from iron stores due to inflammation. Oral iron is first line treatment, but often hampered by intolerance. Intravenous iron is safe, and the preferred treatment in patients with chronic inflammation and bowel diseases. The goal of treatment is normalisation of hemoglobin concentration and recovery of iron stores. It is important to follow up treatment to ensure that these objectives are met and also long-term in patients with chronic iron loss and/or inflammation to avoid recurrence of anemia.

  11. A randomized trial of iron isomaltoside versus iron sucrose in patients with iron deficiency anemia.

    Science.gov (United States)

    Derman, Richard; Roman, Eloy; Modiano, Manuel R; Achebe, Maureen M; Thomsen, Lars L; Auerbach, Michael

    2017-03-01

    Iron deficiency anemia (IDA) is common in many chronic diseases, and intravenous (IV) iron offers a rapid and efficient iron correction. This trial compared the efficacy and safety of iron isomaltoside and iron sucrose in patients with IDA who were intolerant of, or unresponsive to, oral iron. The trial was an open-label, comparative, multi-center trial. Five hundred and eleven patients with IDA from different causes were randomized 2:1 to iron isomaltoside or iron sucrose and followed for 5 weeks. The cumulative dose of iron isomaltoside was based on body weight and hemoglobin (Hb), administered as either a 1000 mg infusion over more than 15 minutes or 500 mg injection over 2 minutes. The cumulative dose of iron sucrose was calculated according to Ganzoni and administered as repeated 200 mg infusions over 30 minutes. The mean cumulative dose of iron isomaltoside was 1640.2 (standard deviation (SD): 357.6) mg and of iron sucrose 1127.9 (SD: 343.3) mg. The primary endpoint was the proportion of patients with a Hb increase ≥2 g/dL from baseline at any time between weeks 1-5. Both non-inferiority and superiority were confirmed for the primary endpoint, and a shorter time to Hb increase ≥2 g/dL was observed with iron isomaltoside. For all biochemical efficacy parameters, faster and/or greater improvements were found with iron isomaltoside. Both treatments were well tolerated; 0.6% experienced a serious adverse drug reaction. Iron isomaltoside was more effective than iron sucrose in achieving a rapid improvement in Hb. Furthermore, iron isomaltoside has an advantage over iron sucrose in allowing higher cumulative dosing in fewer administrations. Both treatments were well tolerated in a broad population with IDA.

  12. Iron deficiency and cognitive functions

    Directory of Open Access Journals (Sweden)

    Jáuregui-Lobera I

    2014-11-01

    Full Text Available Ignacio Jáuregui-Lobera Department of Nutrition and Bromatology, Pablo de Olavide University, Seville, Spain Abstract: Micronutrient deficiencies, especially those related to iodine and iron, are linked to different cognitive impairments, as well as to potential long-term behavioral changes. Among the cognitive impairments caused by iron deficiency, those referring to attention span, intelligence, and sensory perception functions are mainly cited, as well as those associated with emotions and behavior, often directly related to the presence of iron deficiency anemia. In addition, iron deficiency without anemia may cause cognitive disturbances. At present, the prevalence of iron deficiency and iron deficiency anemia is 2%–6% among European children. Given the importance of iron deficiency relative to proper cognitive development and the alterations that can persist through adulthood as a result of this deficiency, the objective of this study was to review the current state of knowledge about this health problem. The relevance of iron deficiency and iron deficiency anemia, the distinction between the cognitive consequences of iron deficiency and those affecting specifically cognitive development, and the debate about the utility of iron supplements are the most relevant and controversial topics. Despite there being methodological differences among studies, there is some evidence that iron supplementation improves cognitive functions. Nevertheless, this must be confirmed by means of adequate follow-up studies among different groups. Keywords: iron deficiency, anemia, cognitive functions, supplementation

  13. Iron prophylaxis during pregnancy -- how much iron is needed? A randomized dose- response study of 20-80 mg ferrous iron daily in pregnant women

    DEFF Research Database (Denmark)

    Milman, Nils; Bergholt, Thomas; Eriksen, Lisbeth

    2005-01-01

    To determine the lowest dose of iron preventative of iron deficiency and iron deficiency anemia in pregnancy.......To determine the lowest dose of iron preventative of iron deficiency and iron deficiency anemia in pregnancy....

  14. Oral iron chelators.

    Science.gov (United States)

    Kwiatkowski, Janet L

    2010-02-01

    Effective chelation therapy can prevent or reverse organ toxicity related to iron overload, yet cardiac complications and premature death continue to occur, largely related to difficulties with compliance in patients who receive parenteral therapy. The use of oral chelators may be able to overcome these difficulties and improve patient outcomes. A chelator's efficacy at cardiac and liver iron removal and side-effect profile should be considered when tailoring individual chelation regimens. Broader options for chelation therapy, including possible combination therapy, should improve clinical efficacy and enhance patient care.

  15. Iron deficiency anemia in children.

    Science.gov (United States)

    Subramaniam, Girish; Girish, Meenakshi

    2015-06-01

    Iron deficiency is not just anemia; it can be responsible for a long list of other manifestations. This topic is of great importance, especially in infancy and early childhood, for a variety of reasons. Firstly, iron need is maximum in this period. Secondly, diet in infancy is usually deficient in iron. Thirdly and most importantly, iron deficiency at this age can result in neurodevelopmental and cognitive deficits, which may not be reversible. Hypochromia and microcytosis in a complete blood count (CBC) makes iron deficiency anemia (IDA) most likely diagnosis. Absence of response to iron should make us look for other differential diagnosis like β thalassemia trait and anemia of chronic disease. Celiac disease is the most important cause of true IDA not responding to oral iron therapy. While oral ferrous sulphate is the cheapest and most effective therapy for IDA, simple nonpharmacological and pharmacological measures can go a long way in prevention of iron deficiency.

  16. Hepcidin Suppresses Brain Iron Accumulation by Downregulating Iron Transport Proteins in Iron-Overloaded Rats.

    Science.gov (United States)

    Du, Fang; Qian, Zhong-Ming; Luo, Qianqian; Yung, Wing-Ho; Ke, Ya

    2015-08-01

    Iron accumulates progressively in the brain with age, and iron-induced oxidative stress has been considered as one of the initial causes for Alzheimer's disease (AD) and Parkinson's disease (PD). Based on the role of hepcidin in peripheral organs and its expression in the brain, we hypothesized that this peptide has a role to reduce iron in the brain and hence has the potential to prevent or delay brain iron accumulation in iron-associated neurodegenerative disorders. Here, we investigated the effects of hepcidin expression adenovirus (ad-hepcidin) and hepcidin peptide on brain iron contents, iron transport across the brain-blood barrier, iron uptake and release, and also the expression of transferrin receptor-1 (TfR1), divalent metal transporter 1 (DMT1), and ferroportin 1 (Fpn1) in cultured microvascular endothelial cells and neurons. We demonstrated that hepcidin significantly reduced brain iron in iron-overloaded rats and suppressed transport of transferrin-bound iron (Tf-Fe) from the periphery into the brain. Also, the peptide significantly inhibited expression of TfR1, DMT1, and Fpn1 as well as reduced Tf-Fe and non-transferrin-bound iron uptake and iron release in cultured microvascular endothelial cells and neurons, while downregulation of hepcidin with hepcidin siRNA retrovirus generated opposite results. We concluded that, under iron-overload, hepcidin functions to reduce iron in the brain by downregulating iron transport proteins. Upregulation of brain hepcidin by ad-hepcidin emerges as a new pharmacological treatment and prevention for iron-associated neurodegenerative disorders.

  17. Colour Metallography of Cast Iron

    Institute of Scientific and Technical Information of China (English)

    Zhou Jiyang

    2009-01-01

    @@ Grey Iron(Ⅲ) 2.5 Crystallization of the LTF during final stage of eutectic solidification of grey iron In the final stage of eutectic solidification, eutectic cells grow gradually into large sizes; the liquid iron between the cells enters the last stage of solidification. At this time, the region of the remaining liquid iron is called last to freeze volume, LTF in short, as shown in Fig.2-39.

  18. Single-step substitution of all the α, β-positions in pyrrole: choice of binuclear versus multinuclear complex of the novel polydentate ligand.

    Science.gov (United States)

    Ghorai, Debasish; Mani, Ganesan

    2014-04-21

    The α and β-positions of pyrrole were substituted with 3,5-dimethylpyrazolylmethyl groups in a single step that involved the reaction between 2,5-dimethylaminomethylpyrrole and 3,5-dimethylpyrazole-1-carbinol, affording 2,3,4,5-tetrakis(3,5-dimethylpyrazol-1-ylmethyl)pyrrole LH in 40% yield. The coordination chemistry of this new polydentate ligand LH was explored by synthesizing several Pd(II), Cu(I), and Ag(I) complexes. When LH was used as a neutral ligand with [Pd(COD)Cl2], AgBF4, and CuX (X = Cl and I), compartmental type binuclear Pd(II) and Ag(I) complexes such as [Pd2Cl4(μ-C4HN-2,3,4,5-(CH2Me2pz)4-N,N,N,N)] and [Ag2(μ-C4HN-2,3,4,5-(CH2Me2pz)4-N,N,N,N)(CH3CN)2](2+)[BF4(-)]2 and cage-like copper(I) complexes [Cu2(μ-X)(μ-C4HN-2,3,4,5-(CH2Me2pz)4-N,N,N,N)](+)[CuX2](-) (X = Cl and I) containing a halide ion bridging in a bent fashion were obtained, respectively. Conversely, when the same metal precursors were treated with LH in the presence of n-BuLi, the multinuclear complexes [Pd2Cl3(μ-C4N-2,3,4,5-(CH2Me2pz)4-N,N,N,N,N)], [(Cu2(μ-I){μ-C4N-2,3,4,5-(CH2Me2pz)4-N,N,N,N,N})2Cu](+)I(-), and [Ag4(μ-C4N-2,3,4,5-(CH2Me2pz)4-N,N,N,N)2](2+)[BF4(-)]2 were obtained. In addition, the treatment of LH with [Pd(OAc)2] gave the mononuclear complex, [Pd(OAc)(C4N-2,3,4,5-(CH2Me2pz)4-N,N,N)]. The chloride analogue of this complex was obtained by the reaction of LH with [Pd(COD)Cl2] in the presence of triethylamine. The structures of all complexes were determined by single-crystal X-ray diffraction analyses, which revealed interesting structural features, including pyrazole arms adopting different conformations with respect to the pyrrole ring plane and linear two- and three-coordinated copper(I) and silver(I) atoms exhibiting weak interactions between the metal and the pyrrolic carbon atoms and Ag(I)···Ag(I) interactions. The observed shorter metal pyrrolide nitrogen (M-N) bond distances and the elongation of the C-C double and single bond distances of the pyrrole

  19. Synthesis and X-ray structure analysis of a new binuclear Schiff base Co(II) complex with the ligand N,N'-bis(3-methoxysalicylidene)-1,4-butanediamine

    Energy Technology Data Exchange (ETDEWEB)

    Nasr-Esfahani, M., E-mail: m-nasresfahani@iaun.ac.ir [Islamic Azad University, Najafabad Branch, Department of Materials Science and Engineering (Iran, Islamic Republic of)

    2009-12-15

    The title binuclear complex, tris[N,N-bis(3-methoxysalicylidene)-1,4-diaminobutane] dicobalt(II), C{sub 60}H{sub 70}Co{sub 2}N{sub 6}O{sub 15}, was prepared by the reaction of the tetradentate Schiff base ligand bis(3-methoxysalicylidene)-1,4-diaminobutane and Co(CH{sub 3}COO){sub 2} . 4H{sub 2}O in a ethanol solution and structurally characterized by single-crystal X-ray diffraction. This complex has a dinuclear structure where two Co(II) ions are bridged by one N{sup 0},N'-bis(3-methoxysalicylidene)-1,4-diaminobutane. The two Co(II) ions, have two distorted octahedral coordination involving two O and two N atoms.

  20. Cytotoxicity of copper(II)-complexes with some S-alkyl derivatives of thiosalicylic acid. Crystal structure of the binuclear copper(II)-complex with S-ethyl derivative of thiosalicylic acid

    Science.gov (United States)

    Nikolić, Miloš V.; Mijajlović, Marina Ž.; Jevtić, Verica V.; Ratković, Zoran R.; Novaković, Slađana B.; Bogdanović, Goran A.; Milovanović, Jelena; Arsenijević, Aleksandar; Stojanović, Bojana; Trifunović, Srećko R.; Radić, Gordana P.

    2016-07-01

    The spectroscopically predicted structure of the obtained copper(II)-complex with S-ethyl derivative of thiosalicylic acid was confirmed by X-ray structural study and compared to previously reported crystal structure of the Cu complex with S-methyl derivative. Single crystals suitable for X-ray measurements were obtained by slow crystallization from a water solution. Cytotoxic effects of S-alkyl (R = benzyl (L1), methyl (L2), ethyl (L3), propyl (L4) and butyl (L5)) derivatives of thiosalicylic acid and the corresponding binuclear copper(II)-complexes on murine colon carcinoma cell lines, CT26 and CT26.CL25 and human colon carcinoma cell line HCT-116 were reported here. The analysis of cancer cell viability showed that all the tested complexes had low cytotoxic effect on murine colon carcinoma cell lines, but several times higher cytotoxicity on normal human colon carcinoma cells.

  1. Phytases for improved iron absorption

    DEFF Research Database (Denmark)

    Nielsen, Anne Veller Friis; Meyer, Anne S.

    2016-01-01

    Phytase enzymes present an alternative to iron supplements, because they have been shown to improve iron absorption by means of catalysing the degradation of a potent iron absorption inhibitor: phytic acid. Phytic acid is a hexaphosphate of inositol and is particularly prevalent in cereal grains,...

  2. Iron deficiency and cardiovascular disease

    NARCIS (Netherlands)

    von Haehling, Stephan; Jankowska, Ewa A.; van Veldhuisen, Dirk J.; Ponikowski, Piotr; Anker, Stefan D.

    2015-01-01

    Iron deficiency affects up to one-third of the world's population, and is particularly common in elderly individuals and those with certain chronic diseases. Iron excess can be detrimental in cardiovascular illness, and research has now also brought anaemia and iron deficiency into the focus of card

  3. Iron deficiency anemia in children

    OpenAIRE

    Pochinok, T. V.

    2016-01-01

    In the article the role of iron in the human body is highlighted. The mechanism of development of iron deficiency states, their consequences and the basic principles of diagnosis and correction of children of different ages are shown.Key words: children, iron deficiency anemia, treatment.

  4. 不对称结构双核铜(I)配合物的合成、反应与荧光光谱%Synthesis, Reaction and Luminescence of Asymmetric Binuclear Copper(I) Complex

    Institute of Scientific and Technical Information of China (English)

    赵东; 孙雨安; 刘应凡; 张传建

    2005-01-01

      Asymmetric binuclear copper(I) complex has been synthesized by the reaction between [Cu(dppm)(ClO4)]2 and 4-vinylpyridine [dppm= bis(diphenylphosphino) methane, C7H7N=4-vinylpyridine] and characterized by specific elemental analyses, 31P NMR and luminescence analysis. The X-ray crystal structure of the title complex shows that dppm and acetylide coordinate as bridging bidentate ligands to the Cu(I) atoms, and 4-vinylpyridine as monodentate ligand. The ClO4- ion is free in the newly prepared binuclear copper(I) complex.%  通过配位催化反应首次合成了含双二苯基膦甲烷(dppm)和4-乙烯吡啶(C7H7N)混合配体的具有不对称结构双核铜(I)配合物[Cu2(dppm)2(CH2=CH-C5H4N)2(µ-C≡CH)](ClO4),并经X射线结构分析和荧光光谱表征了配合物的结构特征。结构分析表明,dppm 作为桥式双齿配体、4-乙烯吡啶作为单齿配体,小分子乙炔以桥式配位分别与铜原子形成四面体配位结构,高氯酸根离子位于配合物外界。

  5. Extracting phosphoric iron under laboratorial conditions smelting bog iron ores

    Science.gov (United States)

    Török, B.; Thiele, A.

    2013-12-01

    In recent years it has been indicated by archaeometric investigations that phosphoric-iron (P-iron, low carbon steel with 0,5-1,5wt% P), which is an unknown and unused kind of steel in the modern industry, was widely used in different parts of the world in medieval times. In this study we try to explore the role of phosphorus in the arhaeometallurgy of iron and answer some questions regarding the smelting bog iron ores with high P-content. XRF analyses were performed on bog iron ores collected in Somogy county. Smelting experiments were carried out on bog iron ores using a laboratory model built on the basis of previously conducted reconstructed smelting experiments in copies of excavated furnaces. The effect of technological parameters on P-content of the resulted iron bloom was studied. OM and SEM-EDS analyses were carried out on the extracted iron and slag samples. On the basis of the material analyses it can be stated that P-iron is usually extracted but the P-content is highly affected by technological parameters. Typical microstructures of P-iron and of slag could also be identified. It could also be established that arsenic usually solved in high content in iron as well.

  6. Iron, transferrin and myelinogenesis

    Science.gov (United States)

    Sergeant, C.; Vesvres, M. H.; Devès, G.; Baron, B.; Guillou, F.

    2003-09-01

    Transferrin (Tf), the iron binding protein of vertebrates serum, is known to be synthesized by oligodendrocytes (Ols) in the central nervous system. It has been postulated that Tf is involved in Ols maturation and myelinogenesis. This link is particularly important in the understanding of a severe human pathology: the multiple sclerosis, which remains without efficient treatment. We generated transgenic mice containing the complete human Tf gene and extensive regulatory sequences from the 5 ' and 3 ' untranslated regions that specifically overexpress Tf in Ols. Brain cytoarchitecture of the transgenic mice appears to be normal in all brain regions examined, total myelin content is increased by 30% and motor coordination is significantly improved when compared with non-transgenic littermates. Tf role in the central nervous system may be related to its affinity for metallic cations. Normal and transgenic mice were used for determination of trace metals (iron, copper and zinc) and minerals (potassium and calcium) concentration in cerebellum and corpus callosum. The freeze-dried samples were prepared to allow proton-induced X-ray emission and Rutherford backscattering spectrometry analyses with the nuclear microprobe in Bordeaux. Preliminary results were obtained and carbon distribution was revealed as a very good analysis to distinguish precisely the white matter region. A comparison of metallic and mineral elements contents in brain between normal and transgenic mice shows that iron, copper and zinc levels remained constant. This result provides evidence that effects of Tf overexpression in the brain do not solely relate to iron transport.

  7. State of the iron

    DEFF Research Database (Denmark)

    Reinisch, Walter; Staun, Michael; Bhandari, Sunil

    2013-01-01

    Iron deficiency anemia (IDA) frequently occurs in patients suffering from inflammatory bowel disease (IBD) and negatively impacts their quality of life. Nevertheless, the condition appears to be both under-diagnosed and undertreated. Regular biochemical screening of patients with IBD for anemia...

  8. Development of iron aluminides

    Energy Technology Data Exchange (ETDEWEB)

    Viswanathan, S.; Sikka, V.K.; Andleigh, V.K. [and others

    1995-06-01

    The primary reason for the poor room-temperature ductility of Fe{sub 3}Al-based alloys is generally accepted to be environmental embrittlement due to hydrogen produced by the reaction of aluminum with water vapor present in the test atmosphere. In the as-cast condition, another possible reason for the low room-temperature ductility is the large grain size (0.5 to 3 mm) of the cast material. While recent studies on iron aluminides in the wrought condition have led to higher room-temperature ductility and increased high-temperature strength, limited studies have been conducted on iron aluminides in the as-cast condition. The purpose of this study was to induce grain refinement of the as-cast alloy through alloying additions to the melt and study the effect on room-temperature ductility as measured by the strain corresponding to the maximum stress obtained in a three-point bend test. A base charge of Fe-28% Al-5% Cr alloy was used; as in previous studies this ternary alloy exhibited the highest tensile ductility of several alloys tested. Iron aluminide alloys are being considered for many structural uses, especially for applications where their excellent corrosion resistance is needed. Several alloy compositions developed at ORNL have been licensed to commercial vendors for development of scale-up procedures. With the licensees and other vendors, several applications for iron aluminides are being pursued.

  9. The New Iron Man

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Sinosteel wins a hard-fought victory in the marathon battle for Australia’s Midwest Sinosteel Corp.,one of China’s larg- est steelmakers,has finally clinched its AU$1.36 billion($1.31 billion) takeover of Midwest Corp.,a Perth (Australia)-based iron ore miner,after a

  10. New insights into iron deficiency and iron deficiency anemia.

    Science.gov (United States)

    Camaschella, Clara

    2017-02-13

    Recent advances in iron metabolism have stimulated new interest in iron deficiency (ID) and its anemia (IDA), common conditions worldwide. Absolute ID/IDA, i.e. the decrease of total body iron, is easily diagnosed based on decreased levels of serum ferritin and transferrin saturation. Relative lack of iron in specific organs/tissues, and IDA in the context of inflammatory disorders, are diagnosed based on arbitrary cut offs of ferritin and transferrin saturation and/or marker combination (as the soluble transferrin receptor/ferritin index) in an appropriate clinical context. Most ID patients are candidate to traditional treatment with oral iron salts, while high hepcidin levels block their absorption in inflammatory disorders. New iron preparations and new treatment modalities are available: high-dose intravenous iron compounds are becoming popular and indications to their use are increasing, although long-term side effects remain to be evaluated.

  11. Nutritional iron deficiency: the role of oral iron supplementation.

    Science.gov (United States)

    Lachowicz, J I; Nurchi, V M; Fanni, D; Gerosa, C; Peana, M; Zoroddu, M A

    2014-01-01

    Nutritional iron deficiency represents a relevant health problem mainly in developing countries. Children and pregnant women represent the main target of this disease, and the low amount of bio-available iron mostly depends on plant-based diets. Iron deficiency may have serious consequences, with severe impairment of the immune function leading to infectious diseases. The brain development in embryos and fetuses during gestation can be greatly affected by iron deficiency of the mother with heavy outcomes on the cognition status of children. A better understanding of molecular pathways involved in iron absorption and metabolism are the basis for new strategies for developing a therapy for iron deficiency. Different therapeutic strategies are summarized, and iron fortification appears the best tool.

  12. 49 CFR 192.373 - Service lines: Cast iron and ductile iron.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Service lines: Cast iron and ductile iron. 192.373... Regulators, and Service Lines § 192.373 Service lines: Cast iron and ductile iron. (a) Cast or ductile iron... cast iron pipe or ductile iron pipe is installed for use as a service line, the part of the...

  13. Iron-fortified milk can improve iron status in young women with low iron stores

    NARCIS (Netherlands)

    Scholz-Ahrens, K.E.; Schaafsma, G.; Kip, P.; Elbers, F.; Boeing, H.; Schrezenmeir, J.

    2004-01-01

    A considerable proportion of the populations of developing and industrialised nations does not meet the recommended daily allowance for iron and are thus at risk of chronic iron-deficiency anaemia. In a placebo-controlled, double-blind study we investigated whether supplementation with iron-enriched

  14. Genetic defects of iron transport.

    Science.gov (United States)

    Bannerman, R M

    1976-09-01

    Five genetic traits in man and laboratory animals have major effects on iron transport. The heterogeneous condition, hemochromatosis, in some families appears to segregate as a Mendelian trait, and is associated with defective control of intestinal iron absorption. In the very rare human autosomal recessive trait, atransferrinemia, there is an almost total lack of transferrin and gross maldistribution of iron through the body. In mice, sex-linked anemia (an X-linked recessive trait) causes iron deficiency through defective iron absorption, at the "exit" step; a similar defect probably exists in placental iron transfer. In microcytic anemia of mice, an autosomal recessive trait, iron absorption is also impaired because of a defect of iron entry into cells, which is probably generalized. Belgrade rat anemia, less understood at present, also may involve a major disorder of iron metabolism. Study of these mutations has provided new knowledge of iron metabolism and its genetic control Their phenotypic interaction with nutritional factors, especially the form and quantity of iron in the diet, may provide new insights for the study of nutrition.

  15. High efficiency iron electrode and additives for use in rechargeable iron-based batteries

    Energy Technology Data Exchange (ETDEWEB)

    Narayan, Sri R.; Prakash, G. K. Surya; Aniszfeld, Robert; Manohar, Aswin; Malkhandi, Souradip; Yang, Bo

    2017-02-21

    An iron electrode and a method of manufacturing an iron electrode for use in an iron-based rechargeable battery are disclosed. In one embodiment, the iron electrode includes carbonyl iron powder and one of a metal sulfide additive or metal oxide additive selected from the group of metals consisting of bismuth, lead, mercury, indium, gallium, and tin for suppressing hydrogen evolution at the iron electrode during charging of the iron-based rechargeable battery. An iron-air rechargeable battery including an iron electrode comprising carbonyl iron is also disclosed, as is an iron-air battery wherein at least one of the iron electrode and the electrolyte includes an organosulfur additive.

  16. Osmundiron, cleaved iron bars and slags (Osmundjern, kloder og kalotslagger)

    DEFF Research Database (Denmark)

    Buchwald, Vagn Fabritius

    1996-01-01

    Investigation of so-called Osmund iron, iron bars and slags from iron production in the medieval ages.......Investigation of so-called Osmund iron, iron bars and slags from iron production in the medieval ages....

  17. Combustion iron distribution and deposition

    Science.gov (United States)

    Luo, Chao; Mahowald, N.; Bond, T.; Chuang, P. Y.; Artaxo, P.; Siefert, R.; Chen, Y.; Schauer, J.

    2008-03-01

    Iron is hypothesized to be an important micronutrient for ocean biota, thus modulating carbon dioxide uptake by the ocean biological pump. Studies have assumed that atmospheric deposition of iron to the open ocean is predominantly from mineral aerosols. For the first time we model the source, transport, and deposition of iron from combustion sources. Iron is produced in small quantities during fossil fuel burning, incinerator use, and biomass burning. The sources of combustion iron are concentrated in the industrialized regions and biomass burning regions, largely in the tropics. Model results suggest that combustion iron can represent up to 50% of the total iron deposited, but over open ocean regions it is usually less than 5% of the total iron, with the highest values (ocean biogeochemistry the bioavailability of the iron is important, and this is often estimated by the fraction which is soluble (Fe(II)). Previous studies have argued that atmospheric processing of the relatively insoluble Fe(III) occurs to make it more soluble (Fe(II)). Modeled estimates of soluble iron amounts based solely on atmospheric processing as simulated here cannot match the variability in daily averaged in situ concentration measurements in Korea, which is located close to both combustion and dust sources. The best match to the observations is that there are substantial direct emissions of soluble iron from combustion processes. If we assume observed soluble Fe/black carbon ratios in Korea are representative of the whole globe, we obtain the result that deposition of soluble iron from combustion contributes 20-100% of the soluble iron deposition over many ocean regions. This implies that more work should be done refining the emissions and deposition of combustion sources of soluble iron globally.

  18. Studies on the pathogenesis in iron deficiency anemia Part 1. Urinary iron excretion in iron deficiency anemia patients and rats in various iron states

    OpenAIRE

    1991-01-01

    In the "iron excretion test" , urinary iron excretion after injection of saccharated iron oxide has been reported to be accelerated in relapsing idiopathic iron deficiency anemia. To determine the relevance of urinary iron excretion to clinical factors other than iron metabolism, 15 clinical parameters were evaluated. The serum creatinine level was positively and the serum albumin level was negatively correlated with urinary iron excretion, showing coefficients of r=0.97,-0.86 respectively, a...

  19. Iron deficiency or anemia of inflammation?

    OpenAIRE

    Nairz, Manfred; Theurl, Igor; Wolf, Dominik; Weiss, Günter

    2016-01-01

    Summary Iron deficiency and immune activation are the two most frequent causes of anemia, both of which are based on disturbances of iron homeostasis. Iron deficiency anemia results from a reduction of the body’s iron content due to blood loss, inadequate dietary iron intake, its malabsorption, or increased iron demand. Immune activation drives a diversion of iron fluxes from the erythropoietic bone marrow, where hemoglobinization takes place, to storage sites, particularly the mononuclear ph...

  20. Iron and Prochlorococcus

    Science.gov (United States)

    2009-06-01

    some cyanobacteria has been investigated through culture-based and genomic approaches (Ferreira and Straus, 1994; Katoh et al, 2001; Kutzki, 1998...numerically abundant marine cyanobacterium, Prochlorococcus. With its minimal genome and ubiquity in the global ocean, Prochlorococcus represents a model...then examined the molecular basis for the ability of MIT9313 to grow at lower iron concentrations than MED4 by assessing whole- genome transcription

  1. Iron Curtains ?

    OpenAIRE

    Maria Vlček

    2010-01-01

    This paper explores the emotional and multi-sensorial dimensions of care within a transnational family separated by the Iron Curtain during the Cold War. It will argue that processes of supportive and compassionate engagement amongst transnational kin are not only shaped by long-distance communication, financial support and practical help within specific political and economic contexts, but also by personal desires and interpersonal conflict. The dialectics of proximity and distance are explo...

  2. Iron deficiency and cardiovascular disease.

    Science.gov (United States)

    von Haehling, Stephan; Jankowska, Ewa A; van Veldhuisen, Dirk J; Ponikowski, Piotr; Anker, Stefan D

    2015-11-01

    Iron deficiency affects up to one-third of the world's population, and is particularly common in elderly individuals and those with certain chronic diseases. Iron excess can be detrimental in cardiovascular illness, and research has now also brought anaemia and iron deficiency into the focus of cardiovascular medicine. Data indicate that iron deficiency has detrimental effects in patients with coronary artery disease, heart failure (HF), and pulmonary hypertension, and possibly in patients undergoing cardiac surgery. Around one-third of all patients with HF, and more than one-half of patients with pulmonary hypertension, are affected by iron deficiency. Patients with HF and iron deficiency have shown symptomatic improvements from intravenous iron administration, and some evidence suggests that these improvements occur irrespective of the presence of anaemia. Improved exercise capacity has been demonstrated after iron administration in patients with pulmonary hypertension. However, to avoid iron overload and T-cell activation, it seems that recipients of cardiac transplantations should not be treated with intravenous iron preparations.

  3. Flare Plasma Iron Abundance

    Science.gov (United States)

    Dennis, Brian R.; Dan, Chau; Jain, Rajmal; Schwartz, Richard A.; Tolbert, Anne K.

    2008-01-01

    The equivalent width of the iron-line complex at 6.7 keV seen in flare X-ray spectra suggests that the iron abundance of the hottest plasma at temperatures >approx.10 MK may sometimes be significantly lower than the nominal coronal abundance of four times the photospheric value that is commonly assumed. This conclusion is based on X-ray spectral observations of several flares seen in common with the Ramaty High Energy Solar Spectroscopic Imager (RHESSI) and the Solar X-ray Spectrometer (SOXS) on the second Indian geostationary satellite, GSAT-2. The implications of this will be discussed as it relates to the origin of the hot flare plasma - either plasma already in the corona that is directly heated during the flare energy release process or chromospheric plasma that is heated by flare-accelerated particles and driven up into the corona. Other possible explanations of lower-than-expected equivalent widths of the iron-line complex will also be discussed.

  4. Iron homeostasis: new players, newer insights.

    Science.gov (United States)

    Edison, Eunice S; Bajel, Ashish; Chandy, Mammen

    2008-12-01

    Although iron is a relatively abundant element in the universe, it is estimated that more than 2 billion people worldwide suffer from iron deficiency anemia. Iron deficiency results in impaired production of iron-containing proteins, the most prominent of which is hemoglobin. Cellular iron deficiency inhibits cell growth and subsequently leads to cell death. Hemochromatosis, an inherited disorder results in disproportionate absorption of iron and the extra iron builds up in tissues resulting in organ damage. As both iron deficiency and iron overload have adverse effects, cellular and systemic iron homeostasis is critically important. Recent advances in the field of iron metabolism have led to newer understanding of the pathways involved in iron homeostasis and the diseases which arise from alteration in the regulators. Although insight into this complex regulation of the proteins involved in iron homeostasis has been obtained mainly through animal studies, it is most likely that this knowledge can be directly extrapolated to humans.

  5. Intestinal Iron Homeostasis and Colon Tumorigenesis

    Directory of Open Access Journals (Sweden)

    Yatrik M. Shah

    2013-06-01

    Full Text Available Colorectal cancer (CRC is the third most common cause of cancer-related deaths in industrialized countries. Understanding the mechanisms of growth and progression of CRC is essential to improve treatment. Iron is an essential nutrient for cell growth. Iron overload caused by hereditary mutations or excess dietary iron uptake has been identified as a risk factor for CRC. Intestinal iron is tightly controlled by iron transporters that are responsible for iron uptake, distribution, and export. Dysregulation of intestinal iron transporters are observed in CRC and lead to iron accumulation in tumors. Intratumoral iron results in oxidative stress, lipid peroxidation, protein modification and DNA damage with consequent promotion of oncogene activation. In addition, excess iron in intestinal tumors may lead to increase in tumor-elicited inflammation and tumor growth. Limiting intratumoral iron through specifically chelating excess intestinal iron or modulating activities of iron transporter may be an attractive therapeutic target for CRC.

  6. Microbial reduction of iron ore

    Science.gov (United States)

    Hoffmann, Michael R.; Arnold, Robert G.; Stephanopoulos, Gregory

    1989-01-01

    A process is provided for reducing iron ore by treatment with microorganisms which comprises forming an aqueous mixture of iron ore, microorganisms operable for reducing the ferric iron of the iron ore to ferrous iron, and a substrate operable as an energy source for the microbial reduction; and maintaining the aqueous mixture for a period of time and under conditions operable to effect the reduction of the ore. Preferably the microorganism is Pseudomonas sp. 200 and the reduction conducted anaerobically with a domestic wastewater as the substrate. An aqueous solution containing soluble ferrous iron can be separated from the reacted mixture, treated with a base to precipitate ferrous hydroxide which can then be recovered as a concentrated slurry.

  7. The irony of iron -- biogenic iron oxides as an iron source to the ocean

    Directory of Open Access Journals (Sweden)

    David eEmerson

    2016-01-01

    Full Text Available Primary productivity in at least a third of the sunlit open ocean is thought to be iron-limited. Primary sources of dissolved iron (dFe to the ocean are hydrothermal venting, flux from the sediments along continental margins, and airborne dust. This article provides a general review of sources of hydrothermal and sedimentary iron to the ocean, and speculates upon the role that iron-cycling microbes play in controlling iron dynamics from these sources. Special attention is paid to iron-oxidizing bacteria (FeOB that live by oxidizing iron and producing biogenic iron oxides as waste products. The presence and ubiquity of FeOB both at hydrothermal systems and in sediments is only beginning to be appreciated. The biogenic oxides they produce have unique properties that could contribute significantly to the dynamics of dFe in the ocean. Changes in the physical and chemical characteristics of the ocean due to climate change and ocean acidification will undoubtedly impact the microbial iron cycle. A better understanding of the contemporary role of microbes in the iron cycle will help in predicting how these changes could ultimately influence marine primary productivity.

  8. Iron deficiency in the young athlete.

    Science.gov (United States)

    Rowland, T W

    1990-10-01

    Although overt anemia is uncommon, depletion of body iron stores is common among adolescent female athletes. Poor dietary iron intake, menstruation, and increased iron losses associated with physical training all appear to be important factors. Whether nonanemic iron deficiency can impair exercise performance is uncertain. Nonetheless, athletes with low ferritin levels are at risk for impaired erythropoiesis and should receive therapeutic iron supplementation.

  9. Pathogenic Mechanisms Underlying Iron Deficiency and Iron Overload: New Insights for Clinical Application

    OpenAIRE

    Kotze, MJ; van Velden, DP; van Rensburg, SJ; Erasmus, R

    2009-01-01

    Iron uptake, utilisation, release and storage occur at the gene level. Individuals with variant forms of genes involved in iron metabolism may have different requirements for iron and are likely to respond differently to the same amount of iron in the diet, a concept termed nutrigenetics. Iron deficiency, iron overload and the anemia of inflammation are the commonest iron-related disorders. While at least four types of hereditary iron overload have been identified to date, our knowledge of th...

  10. Iron in Skin of Mice with Three Etiologies of Systemic Iron Overload

    OpenAIRE

    2005-01-01

    In human hemochromatosis, tissue toxicity is a function of tissue iron levels. Despite reports of skin toxicity in hemochromatosis, little is known about iron levels in skin of individuals with systemic iron overload. We measured skin iron and studied skin histology in three mouse models of systemic iron overload: mice with a deletion of the hemochromatosis (Hfe) gene, mice fed a high iron diet, and mice given parenteral injections of iron. In Hfe−/− mice, iron content in the epidermis and de...

  11. Management of Iron Deficiency Anemia

    OpenAIRE

    Jimenez, Kristine; Kulnigg-Dabsch, Stefanie; Gasche, Christoph

    2015-01-01

    Anemia affects one-fourth of the world’s population, and iron deficiency is the predominant cause. Anemia is associated with chronic fatigue, impaired cognitive function, and diminished well-being. Patients with iron deficiency anemia of unknown etiology are frequently referred to a gastroenterologist because in the majority of cases the condition has a gastrointestinal origin. Proper management improves quality of life, alleviates the symptoms of iron deficiency, and reduces the need for blo...

  12. Iron fortification and iron supplementation are cost-effective interventions to reduce iron deficiency in four subregions of the world

    NARCIS (Netherlands)

    C. Knai; M. Sharan; R.M.P.M. Baltussen (Rob)

    2004-01-01

    textabstractIron deficiency is the most common and widespread nutritional disorder in the world, affecting millions of people in both nonindustrialized and industrialized countries. We estimated the costs, effects, and cost-effectiveness of iron supplementation and iron fortificati

  13. Chemiluminescence of iron-chlorophyllin.

    Science.gov (United States)

    Nagoshi, Toshimasa; Ohno, Osamu; Kotake, Tomohiko; Igarashi, Shukuro

    2005-01-01

    The iron-chlorophyllin complex was found to be chemiluminescent (CL) in an acetonitrile (22%)/water mixed solvent. In the presence of hydrogen peroxide, when iron-chlorophyllin was added to the mixed solvent, a sharp CL signal immediately appeared. Also, analysis of the absorption spectra revealed decomposition of iron-chlorophyllin (based on decrease in absorbance at 396 nm), hence iron-chlorophyllin is the CL substance. Moreover, the CL intensity decreased in the presence of potassium thiocyanate (KSCN), indicating that the axial coordinative position of iron-chlorophyllin acts as a point of catalytic activation. In addition, when fluorophores were present with iron-chlorophyllin CL, their CL intensity values were similar to or greater than that of the well-known trichlorophenylperoxalate ester (TCPO) CL. Thus, during the decomposition reaction of iron-chlorophyllin, the latter transfers its energy to the coexisting fluorophores. Moreover, since the decomposed compound in this CL reaction had a fluorescence, it was found that the iron-chlorophyllin also functions as an energy donor. Therefore, the iron-chlorophyllin complex acts not only as a CL substance, but also as a catalyst and energy donor in the reaction.

  14. Iron Deficiency Anemia in Pregnancy.

    Science.gov (United States)

    Breymann, Christian

    2015-10-01

    Anemia is a common problem in obstetrics and perinatal care. Any hemoglobin below 10.5 g/dL can be regarded as true anemia regardless of gestational age. Reasons for anemia in pregnancy are mainly nutritional deficiencies, parasitic and bacterial diseases, and inborn red blood cell disorders such as thalassemias. The main cause of anemia in obstetrics is iron deficiency, which has a worldwide prevalence between estimated 20%-80% and consists of a primarily female population. Stages of iron deficiency are depletion of iron stores, iron-deficient erythropoiesis without anemia, and iron deficiency anemia, the most pronounced form of iron deficiency. Pregnancy anemia can be aggravated by various conditions such as uterine or placental bleedings, gastrointestinal bleedings, and peripartum blood loss. In addition to the general consequences of anemia, there are specific risks during pregnancy for the mother and the fetus such as intrauterine growth retardation, prematurity, feto-placental miss ratio, and higher risk for peripartum blood transfusion. Besides the importance of prophylaxis of iron deficiency, the main therapy options for the treatment of pregnancy anemia are oral iron and intravenous iron preparations.

  15. 46 CFR 56.60-10 - Cast iron and malleable iron.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Cast iron and malleable iron. 56.60-10 Section 56.60-10... APPURTENANCES Materials § 56.60-10 Cast iron and malleable iron. (a) The low ductility of cast iron and malleable iron should be recognized and the use of these metals where shock loading may occur should...

  16. 49 CFR 192.489 - Remedial measures: Cast iron and ductile iron pipelines.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Remedial measures: Cast iron and ductile iron... for Corrosion Control § 192.489 Remedial measures: Cast iron and ductile iron pipelines. (a) General graphitization. Each segment of cast iron or ductile iron pipe on which general graphitization is found to...

  17. Iron-Refractory Iron Deficiency Anemia

    Directory of Open Access Journals (Sweden)

    Ebru Yılmaz Keskin

    2015-03-01

    Full Text Available Demir, oksijenin taşınması, DNA sentezi ve hücre çoğalması gibi çeşitli biyolojik reaksiyonlar için vazgeçilmez olduğundan, yaşam için zorunludur. Demir metabolizması ve bu elementin düzenlenmesiyle ilgili bilgilerimiz, son yıllarda belirgin şekilde değişmiştir. Demir metabolizması ile ilgili yeni bozukluklar tanımlanmış ve demirin başka bozuklukların kofaktörü olduğu anlaşılmaya başlamıştır. Hemokromatozis ve demir tedavisine dirençli demir eksikliği anemisi (IRIDA; “iron-refractory iron deficiency anemia” gibi genetik durumlar üzerinde yapılan çalışmalar, vücuttaki demir dengesini kontrol eden moleküler mekanizmalar ile ilgili önemli ipuçları sunmuştur. Bu ilerlemeler, gelecekte, hem genetik hem de kazanılmış demir bozukluklarının daha etkili şekilde tedavi edilmesi amacıyla kullanılabilir. IRIDA, demir eksikliği ile giden durumlarda, hepsidin üretimini baskılayan matriptaz-2’yi kodlayan TMPRSS6 genindeki mutasyonlardan kaynaklanmaktadır. Hastalığın tipik özellikleri, hipokrom, mikrositer anemi, çok düşük ortalama eritrosit hacmi, oral demir tedavisine yanıtsızlık (veya yetersiz yanıt ve parenteral demire kısmi yanıttır. Klasik demir eksikliği anemisinin aksine, serum ferritin değeri genellikle hafif düşük ya da normal aralıkta; serum ve idrar hepsidin değerleri ise, aneminin derecesi ile orantısız şekilde yüksek bulunur. Şimdiye kadar literatürde bildirilmiş olguların sayısı 100’ü geçmediği halde, IRIDA’nın, “atipik” mikrositik anemilerin en sık nedeni olduğu düşünülmektedir. Bu derlemenin amacı, IRIDA hakkındaki güncel bilgileri araştırıcılar ile paylaşmak ve bu alandaki farkındalıklarını arttırmaktır.

  18. Iron oxide surfaces

    Science.gov (United States)

    Parkinson, Gareth S.

    2016-03-01

    The current status of knowledge regarding the surfaces of the iron oxides, magnetite (Fe3O4), maghemite (γ-Fe2O3), haematite (α-Fe2O3), and wüstite (Fe1-xO) is reviewed. The paper starts with a summary of applications where iron oxide surfaces play a major role, including corrosion, catalysis, spintronics, magnetic nanoparticles (MNPs), biomedicine, photoelectrochemical water splitting and groundwater remediation. The bulk structure and properties are then briefly presented; each compound is based on a close-packed anion lattice, with a different distribution and oxidation state of the Fe cations in interstitial sites. The bulk defect chemistry is dominated by cation vacancies and interstitials (not oxygen vacancies) and this provides the context to understand iron oxide surfaces, which represent the front line in reduction and oxidation processes. Fe diffuses in and out from the bulk in response to the O2 chemical potential, forming sometimes complex intermediate phases at the surface. For example, α-Fe2O3 adopts Fe3O4-like surfaces in reducing conditions, and Fe3O4 adopts Fe1-xO-like structures in further reducing conditions still. It is argued that known bulk defect structures are an excellent starting point in building models for iron oxide surfaces. The atomic-scale structure of the low-index surfaces of iron oxides is the major focus of this review. Fe3O4 is the most studied iron oxide in surface science, primarily because its stability range corresponds nicely to the ultra-high vacuum environment. It is also an electrical conductor, which makes it straightforward to study with the most commonly used surface science methods such as photoemission spectroscopies (XPS, UPS) and scanning tunneling microscopy (STM). The impact of the surfaces on the measurement of bulk properties such as magnetism, the Verwey transition and the (predicted) half-metallicity is discussed. The best understood iron oxide surface at present is probably Fe3O4(100); the structure is

  19. Iron and iron-related proteins in asbestosis.

    Science.gov (United States)

    ABSTRACT: We tested the postulate that iron homeostasis is altered among patients diagnosed to have asbestosis. Lung tissue from six individuals diagnosed to have had asbestosis at autopsy was stained for iron, ferritin, divalent metal transporter 1 (DMT1), and ferroportin 1 (FP...

  20. Core-shell iron-iron oxide nanoparticles

    DEFF Research Database (Denmark)

    Kuhn, Luise Theil; Bojesen, A.; Timmermann, L.

    2004-01-01

    We present studies of the magnetic properties of core-shell iron-iron oxide nanoparticles. By combining Mossbauer and X-ray absorption spectroscopy we have been able to measure the change from a Fe3O4-like to a gamma-Fe2O3-like composition from the interface to the surface. Furthermore, we have...

  1. Amorphous iron (II) carbonate

    DEFF Research Database (Denmark)

    Sel, Ozlem; Radha, A.V.; Dideriksen, Knud;

    2012-01-01

    exothermic than that of amorphous calcium carbonate (ACC). This suggests that enthalpy of crystallization in carbonate systems is ionic-size controlled, which may have significant implications in a wide variety of conditions, including geological sequestration of anthropogenic carbon dioxide.......Abstract The synthesis, characterization and crystallization energetics of amorphous iron (II) carbonate (AFC) are reported. AFC may form as a precursor for siderite (FeCO3). The enthalpy of crystallization (DHcrys) of AFC is similar to that of amorphous magnesium carbonate (AMC) and more...

  2. Iron-Deficiency Anemia (For Parents)

    Science.gov (United States)

    ... Your 1- to 2-Year-Old Iron-Deficiency Anemia KidsHealth > For Parents > Iron-Deficiency Anemia Print A ... common nutritional deficiency in children. About Iron-Deficiency Anemia Every red blood cell in the body contains ...

  3. Iron Meteorites and Upwelling in Antarctica

    Science.gov (United States)

    Gourlay, B. S.; Behr, E.; Mardon, A.; Behr, E.

    2016-09-01

    In Antarctica, a meteorite stranding zone, stone meteorites are more common than iron. Dr. Evatt's team suggests that the heat conductivity of iron may be opposing the upwelling effects so iron meteorites sink under the ice unlike the stone ones.

  4. Iron-Deficiency Anemia (For Parents)

    Science.gov (United States)

    ... Your 1- to 2-Year-Old Iron-Deficiency Anemia KidsHealth > For Parents > Iron-Deficiency Anemia A A ... common nutritional deficiency in children. About Iron-Deficiency Anemia Every red blood cell in the body contains ...

  5. Hunting for Iron Ore Bargains

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    One of China’s leading steel mills has turned to smaller mines for long-term, lowcost iron ore supplies china’s oldest steel producer is looking to South America to fulfill its iron ore needs in the face of rising prices from

  6. Colour Metallography of Cast Iron

    Institute of Scientific and Technical Information of China (English)

    Zhou Jiyang; Liu Jincheng

    2010-01-01

    @@ Spheroidal Graphite Cast Iron(Ⅲ) 3.6 Solidification morphology of SG iron Solidification morphology refers to the description of change,distribution and interrelationship of the solidification structures such as graphite spheroids,austenite,eutectic cells,etc.[99

  7. The Pharmacokinetics and Pharmacodynamics of Iron Preparations

    Directory of Open Access Journals (Sweden)

    Susanna Burckhardt

    2011-01-01

    Full Text Available Standard approaches are not appropriate when assessing pharmacokinetics of iron supplements due to the ubiquity of endogenous iron, its compartmentalized sites of action, and the complexity of the iron metabolism. The primary site of action of iron is the erythrocyte, and, in contrast to conventional drugs, no drug-receptor interaction takes place. Notably, the process of erythropoiesis, i.e., formation of new erythrocytes, takes 3−4 weeks. Accordingly, serum iron concentration and area under the curve (AUC are clinically irrelevant for assessing iron utilization. Iron can be administered intravenously in the form of polynuclear iron(III-hydroxide complexes with carbohydrate ligands or orally as iron(II (ferrous salts or iron(III (ferric complexes. Several approaches have been employed to study the pharmacodynamics of iron after oral administration. Quantification of iron uptake from radiolabeled preparations by the whole body or the erythrocytes is optimal, but alternatively total iron transfer can be calculated based on known elimination rates and the intrinsic reactivity of individual preparations. Degradation kinetics, and thus the safety, of parenteral iron preparations are directly related to the molecular weight and the stability of the complex. High oral iron doses or rapid release of iron from intravenous iron preparations can saturate the iron transport system, resulting in oxidative stress with adverse clinical and subclinical consequences. Appropriate pharmacokinetics and pharmacodynamics analyses will greatly assist our understanding of the likely contribution of novel preparations to the management of anemia.

  8. The pharmacokinetics and pharmacodynamics of iron preparations.

    Science.gov (United States)

    Geisser, Peter; Burckhardt, Susanna

    2011-01-04

    Standard approaches are not appropriate when assessing pharmacokinetics of iron supplements due to the ubiquity of endogenous iron, its compartmentalized sites of action, and the complexity of the iron metabolism. The primary site of action of iron is the erythrocyte, and, in contrast to conventional drugs, no drug-receptor interaction takes place. Notably, the process of erythropoiesis, i.e., formation of new erythrocytes, takes 3-4 weeks. Accordingly, serum iron concentration and area under the curve (AUC) are clinically irrelevant for assessing iron utilization. Iron can be administered intravenously in the form of polynuclear iron(III)-hydroxide complexes with carbohydrate ligands or orally as iron(II) (ferrous) salts or iron(III) (ferric) complexes. Several approaches have been employed to study the pharmacodynamics of iron after oral administration. Quantification of iron uptake from radiolabeled preparations by the whole body or the erythrocytes is optimal, but alternatively total iron transfer can be calculated based on known elimination rates and the intrinsic reactivity of individual preparations. Degradation kinetics, and thus the safety, of parenteral iron preparations are directly related to the molecular weight and the stability of the complex. High oral iron doses or rapid release of iron from intravenous iron preparations can saturate the iron transport system, resulting in oxidative stress with adverse clinical and subclinical consequences. Appropriate pharmacokinetics and pharmacodynamics analyses will greatly assist our understanding of the likely contribution of novel preparations to the management of anemia.

  9. Iron deficiency in blood donors

    Directory of Open Access Journals (Sweden)

    Armando Cortés

    2005-03-01

    Full Text Available Context: Blood donation results in a substantial loss of iron (200 to 250 mg at each bleeding procedure (425 to 475 ml and subsequent mobilization of iron from body stores. Recent reports have shown that body iron reserves generally are small and iron depletion is more frequent in blood donors than in non-donors. Objective: The aim of this study was to evaluate the frequency of iron deficiency in blood donors and to establish the frequency of iron deficiency in blood donors according to sex, whether they were first-time or multi-time donors. Design: From march 20 to April 5, 2004, three hundred potential blood donors from Hemocentro del Café y Tolima Grande were studied. Diagnostic tests: Using a combination of biochemical measurements of iron status: serum ferritin (RIA, ANNAR and the hemoglobin pre and post-donation (HEMOCUE Vital technology medical . Results: The frequency of iron deficiency in potential blood donors was 5%, and blood donors accepted was 5.1%; in blood donors rejected for low hemoglobin the frequency of iron deficiency was 3.7% and accepted blood donors was 1.7% in male and 12.6% in female. The frequency of iron deficiency was higher in multi-time blood donors than in first-time blood donors, but not stadistic significative. Increase nivel accepted hemoglobina in 1 g/dl no incidence in male; in female increase of 0.5 g/dl low in 25% blood donors accepted with iron deficiency, but increased rejected innecesary in 16.6% and increased is 1 g/dl low blood donors female accepted in 58% (7/12, but increased the rejected innecesary in 35.6%. Conclusions: We conclude that blood donation not is a important factor for iron deficiency in blood donors. The high frequency of blood donors with iron deficiency found in this study suggests a need for a more accurate laboratory trial, as hemoglobin or hematocrit measurement alone is not sufficient for detecting and excluding blood donors with iron deficiency without anemia, and ajustes hacia

  10. Pathology of hepatic iron overload

    Institute of Scientific and Technical Information of China (English)

    Yves Deugnier; Bruno Turlin

    2007-01-01

    Although progress in imaging and genetics allow for a noninvasive diagnosis of most cases of genetic iron overload, liver pathology remains often useful (1) to assess prognosis by grading fibrosis and seeking for associated lesions and (2) to guide the etiological diagnosis, especially when no molecular marker is available.Then, the type of liver siderosis (parenchymal, mesenchymal or mixed) and its distribution throughout the lobule and the liver are useful means for suggesting its etiology: HLA-linked hemochromatosis gene (HFE) hemochromatosis or other rare genetic hemochromatosis,nonhemochromatotic genetic iron overload (ferroportin disease, aceruloplasminemia), or iron overload secondary to excessive iron supply, inflammatory syndrome,noncirrhotic chronic liver diseases including dysmetabolic iron overload syndrome, cirrhosis, and blood disorders.

  11. Iron and Mechanisms of Neurotoxicity

    Directory of Open Access Journals (Sweden)

    Gabriela A. Salvador

    2011-01-01

    Full Text Available The accumulation of transition metals (e.g., copper, zinc, and iron and the dysregulation of their metabolism are a hallmark in the pathogenesis of several neurodegenerative diseases. This paper will be focused on the mechanism of neurotoxicity mediated by iron. This metal progressively accumulates in the brain both during normal aging and neurodegenerative processes. High iron concentrations in the brain have been consistently observed in Alzheimer's (AD and Parkinson's (PD diseases. In this connection, metalloneurobiology has become extremely important in establishing the role of iron in the onset and progression of neurodegenerative diseases. Neurons have developed several protective mechanisms against oxidative stress, among them, the activation of cellular signaling pathways. The final response will depend on the identity, intensity, and persistence of the oxidative insult. The characterization of the mechanisms mediating the effects of iron-induced increase in neuronal dysfunction and death is central to understanding the pathology of a number of neurodegenerative disorders.

  12. Comparative study of oral iron and intravenous iron sucrose for the treatment of iron deficiency anemia in pregnancy

    Directory of Open Access Journals (Sweden)

    Apurva Garg

    2016-12-01

    Full Text Available Background: The aim of this study was to compare the efficacy and safety of iron sucrose with oral iron in the treatment of iron deficiency anemia of pregnancy. Methods: An interventional comparative study was conducted at Jhalawar Medical College, Jhalawar involving 80 pregnant women with iron deficiency anemia from March 2016 to August 2016. Inclusion criteria were gestational age between 24-32 weeks with established iron deficiency anemia, with hemoglobin between 7-10g/dl. Target Hemoglobin was 11 g/dl. In intravenous iron sucrose group iron sucrose dose was calculated from following formula: total iron dose required (mg = 2.4 x body weight in Kg x (target Hb – Patient’s Hb g/dl + 500. In oral iron, group patient received ferrous-sulphate 335 mg daily BD. Hb level were reviewed at 2, 4, 6 weeks. Results: Change in Hemoglobin level from baseline significantly higher in IV iron group than oral iron group. In IV iron, group mean value of baseline Hb was 8.07±0.610 g/dl and in oral iron group was 8.48±0.741 g/dl. At the end of 6-week mean hemoglobin in IV iron sucrose was 10.66±0.743 g/dl and in oral iron group was 10.08±0.860 g/dl. Conclusions: Intravenous iron sucrose elevates more Hb than oral iron, with less adverse effects.

  13. Microbial acquisition of iron from ferric iron bearing minerals

    Energy Technology Data Exchange (ETDEWEB)

    Hersman, L.E. [Los Alamos National Lab., NM (United States); Sposito, G. [Univ. of California, Berkeley, CA (United States)

    1998-12-31

    This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Iron is a universal requirement for all life forms. Although the fourth most abundant element in the geosphere, iron is virtually insoluble at physiological pH in oxidizing environments, existing mainly as very insoluble oxides and hydroxides. Currently it is not understood how iron is solubilized and made available for biological use. This research project addressed this topic by conducting a series of experiments that utilized techniques from both soil microbiology and mineral surface geochemistry. Microbiological analysis consisted of the examination of metabolic and physiological responses to mineral iron supplements. At the same time mineral surfaces were examined for structural changes brought about by microbially mediated dissolution. The results of these experiments demonstrated that (1) bacterial siderophores were able to promote the dissolution of iron oxides, (2) that strict aerobic microorganisms may use anaerobic processes to promote iron oxide dissolution, and (3) that it is possible to image the surface of iron oxides undergoing microbial dissolution.

  14. The zinc binuclear cluster activator AlcR is able to bind to single sites but requires multiple repeated sites for synergistic activation of the alcA gene in Aspergillus nidulans.

    Science.gov (United States)

    Panozzo, C; Capuano, V; Fillinger, S; Felenbok, B

    1997-09-01

    The alcA gene which is part of the recently identified ethanol regulon, is one of the most strongly inducible genes in Aspergillus nidulans. Its transcriptional activation is mediated by the AlcR transactivator which contains a DNA-binding domain belonging to the C6 zinc binuclear cluster family. AlcR differs from the other members of this family by several features, the most striking characteristic being its binding to both symmetric and asymmetric DNA sites with the same apparent affinity. However, AlcR is also able to bind to a single site with high affinity, suggesting that unlike the other C6 proteins, AlcR binds as a monomer. In this report, we show that AlcR targets, to be functional in vivo, have to be organized as inverted or direct repeats. In addition, we show a strong synergistic activation of alcA transcription in which the number and the position of the AlcR-binding sites are crucial. The fact that the AlcR unit for in vitro binding is a single site whereas the in vivo functional unit is a repeat opens the question of the mechanism of the strong alcA transactivation. These results show that AlcR displays both in vitro and in vivo a new range of binding specificity and provides a novel example in the C6 zinc cluster protein family.

  15. Synthesis, crystal structure and properties of binuclear manganese complex [(bipy)2Mn2(μ-O)(μ-Ac)2(H2O)2](ClO4)2

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Binuclear manganese complex [(bipy)2Mn2(μ-O)(μ-Ac)2(H2O)2](ClO4)2 was synthesized by the reaction of MnAc3·2H2O with 2,2′- -bipyridine in the HAc-NaAc buffer (pH = 4.0). X-ray diffraction result for the single crystal shows that the crystal is monoclinic, space group C2/C, with a = 3.408 2(7), b = 0.864 4(2), c = 2.174 9(4) nm, β=105.2°,V =6.186(2) nm3, Z = 8. There are two very strong peaks of UV-Vis spectrum in the range of 400-600 nm, which are similar to those of Mn catalase and Mn ribonuleotide reductase extracted from organisms. Cyclic voltammogram shows that the complex in CH3CN undergoes quasi-reversible one-electron reduction and oxidation at E1/2=1.15 V.

  16. The binuclear nickel center in the A-cluster of acetyl-CoA synthase (ACS) and two biomimetic dinickel complexes studied by X-ray absorption and emission spectroscopy

    Science.gov (United States)

    Schrapers, P.; Mebs, S.; Ilina, Y.; Warner, D. S.; Wörmann, C.; Schuth, N.; Kositzki, R.; Dau, H.; Limberg, C.; Dobbek, H.; Haumann, M.

    2016-05-01

    Acetyl-CoA synthase (ACS) is involved in the bacterial carbon oxide conversion pathway. The binuclear nickel sites in ACS enzyme and two biomimetic synthetic compounds containing a Ni(II)Ni(II) unit (1 and 2) were compared using XAS/XES. EXAFS analysis of ACS proteins revealed similar Ni-N/O/S bond lengths and Ni-Ni/Fe distances as in the crystal structure in oxidized ACS, but elongated Ni-ligand bonds in reduced ACS, suggesting more reduced nickel species. The XANES spectra of ACS and the dinickel complexes showed overall similar shapes, but less resolved pre-edge and edge features in ACS, attributed to more distorted square-planar nickel sites in particular in reduced ACS. DFT calculation of pre-edge absorption and Kβ2,5 emission features reproduced the experimental spectra of the synthetic complexes, was sensitive even to the small geometry differences in 1 and 2, and indicated low-spin Ni(II) sites. Comparison of nickel sites in proteins and biomimetic compounds is valuable for deducing structural and electronic differences in response to ligation and redox changes.

  17. The Regulation of Iron Absorption and Homeostasis

    Science.gov (United States)

    Wallace, Daniel F

    2016-01-01

    Iron is an essential element in biology, required for numerous cellular processes. Either too much or too little iron can be detrimental, and organisms have developed mechanisms for balancing iron within safe limits. In mammals there are no controlled mechanisms for the excretion of excess iron, hence body iron homeostasis is regulated at the sites of absorption, utilisation and recycling. This review will discuss the discoveries that have been made in the past 20 years into advancing our understanding of iron homeostasis and its regulation. The study of iron-associated disorders, such as the iron overload condition hereditary haemochromatosis and various forms of anaemia have been instrumental in increasing our knowledge in this area, as have cellular and animal model studies. The liver has emerged as the major site of systemic iron regulation, being the location where the iron regulatory hormone hepcidin is produced. Hepcidin is a negative regulator of iron absorption and recycling, achieving this by binding to the only known cellular iron exporter ferroportin and causing its internalisation and degradation, thereby reducing iron efflux from target cells and reducing serum iron levels. Much of the research in the iron metabolism field has focussed on the regulation of hepcidin and its interaction with ferroportin. The advances in this area have greatly increased our knowledge of iron metabolism and its regulation and have led to the development of novel diagnostics and therapeutics for iron-associated disorders.

  18. Southern Ocean Iron Experiment (SOFex)

    Energy Technology Data Exchange (ETDEWEB)

    Coale, Kenneth H.

    2005-07-28

    The Southern Ocean Iron Experiment (SOFeX) was an experiment decades in the planning. It's implementation was among the most complex ship operations that SIO has been involved in. The SOFeX field expedition was successful in creating and tracking two experimentally enriched areas of the Southern Ocean, one characterized by low silicic acid, one characterized by high silicic acid. Both experimental sites were replete with abundant nitrate. About 100 scientists were involved overall. The major findings of this study were significant in several ways: (1) The productivity of the southern ocean is limited by iron availability. (2) Carbon uptake and flux is therefore controlled by iron availability (3) In spite of low silicic acid, iron promotes non-silicious phytoplankton growth and the uptake of carbon dioxide. (4) The transport of fixed carbon from the surface layers proceeds with a C:N ratio that would indicate differential remineralization of nitrogen at shallow depths. (5) These finding have major implications for modeling of carbon export based on nitrate utilization. (6) The general results of the experiment indicate that, beyond other southern ocean enrichment experiments, iron inputs have a much wider impact of productivity and carbon cycling than previously demonstrated. Scientific presentations: Coale, K., Johnson, K, Buesseler, K., 2002. The SOFeX Group. Eos. Trans. AGU 83(47) OS11A-0199. Coale, K., Johnson, K. Buesseler, K., 2002. SOFeX: Southern Ocean Iron Experiments. Overview and Experimental Design. Eos. Trans. AGU 83 (47) OS22D-01. Buesseler, K.,et al. 2002. Does Iron Fertilization Enhance Carbon Sequestration? Particle flux results from the Southern Ocean Iron Experiment. Eos. Trans. AGU 83 (47), OS22D-09. Johnson, K. et al. 2002. Open Ocean Iron Fertilization Experiments From IronEx-I through SOFeX: What We Know and What We Still Need to Understand. Eos. Trans. AGU 83 (47), OS22D-12. Coale, K. H., 2003. Carbon and Nutrient Cycling During the

  19. Iron Mountain Electromagnetic Results

    Energy Technology Data Exchange (ETDEWEB)

    Gail Heath

    2012-07-01

    Iron Mountain Mine is located seventeen miles northwest of Redding, CA. After the completion of mining in early 1960s, the mine workings have been exposed to environmental elements which have resulted in degradation in water quality in the surrounding water sheds. In 1985, the EPA plugged ore stoops in many of the accessible mine drifts in an attempt to restrict water flow through the mine workings. During this process little data was gathered on the orientation of the stoops and construction of the plugs. During the last 25 years, plugs have begun to deteriorate and allow acidic waters from the upper workings to flow out of the mine. A team from Idaho National Laboratory (INL) performed geophysical surveys on a single mine drift and 3 concrete plugs. The project goal was to evaluate several geophysical methods to determine competence of the concrete plugs and orientation of the stopes.

  20. Iron bromide vapor laser

    Science.gov (United States)

    Sukhanov, V. B.; Shiyanov, D. V.; Trigub, M. V.; Dimaki, V. A.; Evtushenko, G. S.

    2016-03-01

    We have studied the characteristics of a pulsed gas-discharge laser on iron bromide vapor generating radiation with a wavelength of 452.9 nm at a pulse repetition frequency (PRF) of 5-30 kHz. The maximum output power amounted to 10 mW at a PRF within 5-15 kHz for a voltage of 20-25 kV applied to electrodes of the discharge tube. Addition of HBr to the medium produced leveling of the radial profile of emission. Initial weak lasing at a wavelength of 868.9 nm was observed for the first time, which ceased with buildup of the main 452.9-nm line.

  1. Iron Curtains ?

    Directory of Open Access Journals (Sweden)

    Maria Vlček

    2010-12-01

    Full Text Available This paper explores the emotional and multi-sensorial dimensions of care within a transnational family separated by the Iron Curtain during the Cold War. It will argue that processes of supportive and compassionate engagement amongst transnational kin are not only shaped by long-distance communication, financial support and practical help within specific political and economic contexts, but also by personal desires and interpersonal conflict. The dialectics of proximity and distance are explored through a focus on uses of communication technology, emotional interaction during visits, long-distance engagement through distinct sensorial experiences, and imaginary interaction through the dynamics of internalised presence. The auto/biographical analysis is mainly based on letters, faxes, diaries, interviews and personal memories.

  2. High temperature oxidation of iron-iron oxide core-shell nanowires composed of iron nanoparticles.

    Science.gov (United States)

    Krajewski, M; Brzozka, K; Lin, W S; Lin, H M; Tokarczyk, M; Borysiuk, J; Kowalski, G; Wasik, D

    2016-02-07

    This work describes an oxidation process of iron-iron oxide core-shell nanowires at temperatures between 100 °C and 800 °C. The studied nanomaterial was synthesized through a simple chemical reduction of iron trichloride in an external magnetic field under a constant flow of argon. The electron microscopy investigations allowed determining that the as-prepared nanowires were composed of self-assembled iron nanoparticles which were covered by a 3 nm thick oxide shell and separated from each other by a thin interface layer. Both these layers exhibited an amorphous or highly-disordered character which was traced by means of transmission electron microscopy and Mössbauer spectroscopy. The thermal oxidation was carried out under a constant flow of argon which contained the traces of oxygen. The first stage of process was related to slow transformations of amorphous Fe and amorphous iron oxides into crystalline phases and disappearance of interfaces between iron nanoparticles forming the studied nanomaterial (range: 25-300 °C). After that, the crystalline iron core and iron oxide shell became oxidized and signals for different compositions of iron oxide sheath were observed (range: 300-800 °C) using X-ray diffraction, Raman spectroscopy and Mössbauer spectroscopy. According to the thermal gravimetric analysis, the nanowires heated up to 800 °C under argon atmosphere gained 37% of mass with respect to their initial weight. The structure of the studied nanomaterial oxidized at 800 °C was mainly composed of α-Fe2O3 (∼ 93%). Moreover, iron nanowires treated above 600 °C lost their wire-like shape due to their shrinkage and collapse caused by the void coalescence.

  3. Technology of Iron Carbide Synthesis

    Institute of Scientific and Technical Information of China (English)

    M.Bahgat

    2006-01-01

    Iron carbides are very promising metallurgical products and can be used for steelmaking process, where it plays as an alternative raw material with significant economic advantages. Also it has many other applications,e.g. catalysts, magnets, sensors. The present review investigates the different properties and uses of the iron carbides. The commercial production and the different varieties for the iron carbides synthesis (gaseous carburization, mechanochemical synthesis, laser pyrolysis, plasma pyrolysis, chemical vapor deposition and ion implantation) were reviewed. Also the effect of different factors on the carburization process like gas composition, raw material, temperature, reaction time, catalyst presence and sulfur addition was indicated.

  4. Austempered ductile iron process development

    Science.gov (United States)

    Gupta, C. D.; Keough, J. R.; Pramstaller, D. M.

    1986-11-01

    Pressure from imports and material substitution has severly affected demand for domestic iron industry products. It is estimated that the potential market for Austempered Ductile Iron (ADI) is as large as the market for carburized and/or through hardened forgings. The primary interest in ADI is generated by the economics of process. Improved machinability and reduced processing costs as well as interesting physical properties has created an enormous interest in all metalworking industries towards ADI. The development of gas-fired austempering processes and resoluton of technical and economic uncertainities concerning the process will help improve the outlook for iron founderies.

  5. [Phosphate metabolism and iron deficiency].

    Science.gov (United States)

    Yokoyama, Keitaro

    2016-02-01

    Autosomal dominant hypophosphatemic rickets(ADHR)is caused by gain-of-function mutations in FGF23 that prevent its proteolytic cleavage. Fibroblast growth factor 23(FGF23)is a hormone that inhibits renal phosphate reabsorption and 1,25-dihydroxyvitamin D biosynthesis. Low iron status plays a role in the pathophysiology of ADHR. Iron deficiency is an environmental trigger that stimulates FGF23 expression and hypophosphatemia in ADHR. It was reported that FGF23 elevation in patients with CKD, who are often iron deficient. In patients with nondialysis-dependent CKD, treatment with ferric citrate hydrate resulted in significant reductions in serum phosphate and FGF23.

  6. Magnetic study of iron sorbitol

    Energy Technology Data Exchange (ETDEWEB)

    Lazaro, F.J. E-mail: osoro@posta.unizar.es; Larrea, A.; Abadia, A.R.; Romero, M.S

    2002-09-01

    A magnetic study of iron sorbitol, an iron-containing drug to treat the iron deficiency anemia is presented. Transmission electron microscopy reveals that the system contains nanometric particles with an average diameter of 3 nm whose composition is close to two-line ferrihydrite. The characterisation by magnetisation and AC susceptibility measurements indicates superparamagnetic behaviour with progressive magnetic blocking starting at 8 K. The quantitative analysis of the magnetic results indicates that the system consists of an assembly of very small magnetic moments, presumably originated by spin uncompensation of the antiferromagnetic nanoparticles, with Arrhenius type magnetic dynamics.

  7. Hydrolysis of soybean protein improves iron bioavailability

    Science.gov (United States)

    Iron is an important trace metal element in human body. Iron deficiency affects human health, especially pregnant women and children. Soybean protein is a popular food in Asia and can contain a high amount of iron (145.70±0.74 ug/g); however, it is usually reported as an inhibitor of iron absorption...

  8. Iron incorporation and post-malaria anaemia

    Science.gov (United States)

    Iron supplementation is employed to treat post-malarial anaemia in environments where iron deficiency is common. Malaria induces an intense inflammatory reaction that stalls reticulo-endothelial macrophagal iron recycling from haemolysed red blood cells and inhibits oral iron absorption, but the mag...

  9. Placental iron uptake and its regulation

    NARCIS (Netherlands)

    M. Bierings (Marc)

    1989-01-01

    textabstractIron transport in pregnancy is an active one-way process, from mother to fetus. Early in gestation fetal iron needs are low, and so is trans-placental transport, but as erythropoiesis develops, rising fetal iron needs are met by trans-placental iron transport. Apparently, the fetus is pr

  10. Iron excess in recreational marathon runners

    NARCIS (Netherlands)

    Mettler, S.; Zimmermann, M.B.

    2010-01-01

    Background/Objectives: Iron deficiency and anemia may impair athletic performance, and iron supplements are commonly consumed by athletes. However, iron overload should be avoided because of the possible long-term adverse health effects. Methods: We investigated the iron status of 170 male and femal

  11. 21 CFR 522.1182 - Iron injection.

    Science.gov (United States)

    2010-04-01

    ... equivalent of: (1) 100 milligrams (mg) of elemental iron derived from: (i) Ferric hydroxide; (ii) Ferric oxide; or (iii) Elemental iron. (2) 200 mg of elemental iron derived from ferric hydroxide. (b) Sponsors... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Iron injection. 522.1182 Section 522.1182 Food...

  12. Reductive iron assimilation and intracellular siderophores assist extracellular siderophore-driven iron homeostasis and virulence

    Science.gov (United States)

    Iron is an essential nutrient and prudent iron acquisition and management are key traits of a successful pathogen. Fungi use nonribosomally synthesized secreted iron chelators (siderophores) or Reductive Iron Assimilation (RIA) mechanisms to acquire iron in a high affinity manner. Previous studies...

  13. Towards advanced structural analysis of iron oxide clusters on the surface of γ-Al{sub 2}O{sub 3} using EXAFS

    Energy Technology Data Exchange (ETDEWEB)

    Boubnov, Alexey [Institute for Chemical Technology and Polymer Chemistry, Karlsruhe Institute of Technology, Kaiserstr. 12, D-76131 Karlsruhe (Germany); Institute of Catalysis Research and Technology, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen (Germany); Roppertz, Andreas [Institute of Energy Process Engineering and Chemical Engineering, Chair of Reaction Engineering, Technical University of Freiberg, Fuchsmuehlenweg 9, D-09599 Freiberg (Germany); Kundrat, Matthew D. [Center for Functional Nanostructures and Institute of Physical Chemistry, Karlsruhe Institute of Technology, Kaiserstr. 12, D-76131 Karlsruhe (Germany); Mangold, Stefan [Institut für Beschleunigerphysik und Technologie (IBPT), Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen (Germany); Reznik, Boris [Institute of Applied Geosciences, Karlsruhe Institute of Technology, Kaiserstr. 12, D-76131 Karlsruhe (Germany); Jacob, Christoph R. [Center for Functional Nanostructures and Institute of Physical Chemistry, Karlsruhe Institute of Technology, Kaiserstr. 12, D-76131 Karlsruhe (Germany); Institute of Physical and Theoretical Chemistry, TU Braunschweig, Hans-Sommer-Str. 10, D-38106 Braunschweig (Germany); Kureti, Sven [Institute of Energy Process Engineering and Chemical Engineering, Chair of Reaction Engineering, Technical University of Freiberg, Fuchsmuehlenweg 9, D-09599 Freiberg (Germany); Grunwaldt, Jan-Dierk, E-mail: grunwaldt@kit.edu [Institute for Chemical Technology and Polymer Chemistry, Karlsruhe Institute of Technology, Kaiserstr. 12, D-76131 Karlsruhe (Germany); Institute of Catalysis Research and Technology, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen (Germany)

    2016-11-15

    Highlights: • Analysis of isolated and oligomeric FeOx (x = 4, 5) on Al{sub 2}O{sub 3} by XANES and EXAFS. • Iron is trivalent and is mainly located at octahedral lattice sites of Al{sub 2}O{sub 3}. • Low Fe loading (0.1%) guarantees high dispersion of catalytically active iron sites. • Surface Fe-cluster on Al{sub 2}O{sub 3} and DFT-optimised Fe-doped Al{sub 2}O{sub 3} as input models for EXAFS. • Interactions of iron with support are well-accounted for using realistic models. - Abstract: Iron oxide centres are structurally investigated in 0.1% Fe/γ-Al{sub 2}O{sub 3}, which is known as highly active catalyst, for instance in the oxidation of CO. The sample was characterised by using X-ray absorption spectroscopy (XAS) in terms of X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS), Mössbauer spectroscopy, X-ray diffraction (XRD) and transmission electron microscopy (TEM). These analyses evidenced high dispersion of the iron oxide entities without significant presence of bulk-like aggregates associated with the low Fe content of the catalyst. A library of structural models of Al{sub 2}O{sub 3}-supported surface Fe was created as input for EXAFS fitting. Additionally, several model structures of Fe substituting Al ions in bulk γ-Al{sub 2}O{sub 3} were created with optimised geometry based on density-functional theory (DFT) calculations. From EXAFS refinement of the best 8 out of 24 models, it was found that the trivalent Fe ions are coordinated by 4–5 oxygen atoms and are located on octahedral lattice sites of the exposed surfaces of γ-Al{sub 2}O{sub 3}. These iron oxide species exist mainly as a mixture of monomeric and binuclear species and due to the low concentration represent suitable model systems as alternative to single crystal systems for structure-function relationships.

  14. Iron deficiency anemia in heart failure.

    Science.gov (United States)

    Arora, Natasha P; Ghali, Jalal K

    2013-07-01

    Anemia and iron deficiency are quite prevalent in patients with heart failure (HF) and may overlap. Both anemia and iron deficiency are associated with worse symptoms and adverse clinical outcomes. In the past few years, there has been an enormous interest in the subject of iron deficiency and its management in patients with HF. In this review, the etiology and relevance of iron deficiency, iron metabolism in the setting of HF, studies on iron supplementation in patients with HF and potential cardiovascular effects of subclinical iron overload are discussed.

  15. Directly observed iron supplementation for control of iron deficiency anemia

    Directory of Open Access Journals (Sweden)

    Mohan Bairwa

    2017-01-01

    Full Text Available Anemia is major public health problem affecting 1.6 billion people worldwide. The poor compliance of iron supplementation remains main contributor for high prevalence of anemia. The current paper reviewed the effectiveness of direct observation of oral iron supplementation on anemia. A systematic search was performed through electronic databases and local libraries. Search strategies used subject headings and key words “directly observed” and “iron supplementation.” Searches were sought through April 2014. A total of 14 articles were included in the study. Findings were presented in three categories. First, all of those reported an improvement in compliance of iron supplementation. Second, reduction in the prevalence of anemia was reported by all and third, all except one reported increased blood hemoglobin level. Directly observed an iron supplementation is an effective approach for prevention and management of anemia in vulnerable groups. However, larger trials are needed before concluding that scaling up directly observed iron supplementation through community health volunteers would be beneficial.

  16. Iron metabolism in the mononuclear phagocyte system

    Institute of Scientific and Technical Information of China (English)

    Weina Kong; Xianglin Duan; Zhenhua Shi; Yanzhong Chang

    2008-01-01

    The maintenance of body iron homeostasis requires the coordination of multiple regulatory mechanisms of iron metabolism.The mononuclear phagocyte system (MPS,composed of monocytes,macrophages,and their precursor cells) is crucial in the maintenance of iron homeostasis.Recycling of iron is carried out by specialized macrophages via engulfment of aged erythrocytes.The iron stores of macrophages depend on the levels of recovered and exported iron.However,the molecular mechanisms underlying iron homeostasis in macrophages are poorly understood.Recent studies characterizing the function and regulation of natural resistance-associated macrophage protein 1 (Nrampl),divalent metal transporter 1 (DMTI),HLA-linked hemechromatosis gene (HFE),ferroportin 1 (FPN1),and hepcidin are rapidly expanding our knowledge on the molecular level of MPS iron handling.These studies are deepening our understanding about the molecular mechanism of iron homeostasis and iron-related diseases.

  17. IRON-TOLERANT CYANOBACTERIA: IMPLICATIONS FOR ASTROBIOLOGY

    Science.gov (United States)

    Brown, Igor I.; Allen, Carlton C.; Mummey, Daniel L.; Sarkisova, Svetlana A.; McKay, David S.

    2006-01-01

    The review is dedicated to the new group of extremophiles - iron tolerant cyanobacteria. The authors have analyzed earlier published articles about the ecology of iron tolerant cyanobacteria and their diversity. It was concluded that contemporary iron depositing hot springs might be considered as relative analogs of Precambrian environment. The authors have concluded that the diversity of iron-tolerant cyanobacteria is understudied. The authors also analyzed published data about the physiological peculiarities of iron tolerant cyanobacteria. They made the conclusion that iron tolerant cyanobacteria may oxidize reduced iron through the photosystem of cyanobacteria. The involvement of both Reaction Centers 1 and 2 is also discussed. The conclusion that iron tolerant protocyanobacteria could be involved in banded iron formations generation is also proposed. The possible mechanism of the transition from an oxygenic photosynthesis to an oxygenic one is also discussed. In the final part of the review the authors consider the possible implications of iron tolerant cyanobacteria for astrobiology.

  18. Phytases for Improved Iron Absorption

    DEFF Research Database (Denmark)

    Nielsen, Anne Veller Friis; Nyffenegger, Christian; Meyer, Anne S.

    2014-01-01

    Microbial phytases (EC 3.1.3.8) catalyse dephosphorylation of phytic acid, which is the primary storage compound for phosphorous in cereal kernels. The negatively charged phosphates in phytic acid chelate iron (Fe3+) and thus retards iron bioavailability in humans 1. Supplementation of microbial...... phytase can improve iron absorption from cereal-based diets 2. In order for phytase to catalyse iron release in vivo the phytase must be robust to low pH and proteolysis in the gastric ventricle. Our work has compared the robustness of five different microbial phytases, evaluating thermal stability......, activity retention, and extent of dephosphorylation of phytic acid in a simulated low pH/pepsin gastric environment. The five phytases responded differently to the robustness parameters: The Peniophora lycii phytase (Ronozyme NP) was the most thermostable, but the least robust enzyme at low pH, whereas...

  19. Iron pnictide superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Tegel, Marcus Christian

    2011-03-22

    The scope of this dissertation therefore has not only been the synthesis of various new superconducting and non-superconducting iron pnictides of several structural families but also their in-depth crystallographic and physical characterisation. In Chapters 3 - 6, the family of the ZrCuSiAs-type (1111) compounds is subject of discussion. The solid solution series La(Co{sub x}Fe{sub 1-x})PO is analysed regarding magnetic and superconducting properties and the new compounds EuMnPF and REZnPO, as well as the new superconductor parent compound SrFeAsF are presented. Chapters 7 - 9 are dedicated to the new iron arsenide superconductors of the ThCr{sub 2}Si{sub 2}-type (122 family). Therein, also the discovery of the first superconductor in this structural family, Ba{sub 0.6}K{sub 0.4}Fe{sub 2}As{sub 2}, is unveiled. A detailed examination of the complete solid solution series (Ba{sub 1-x}K{sub x})Fe{sub 2}As{sub 2} is presented. Moreover, the crystallographic phase transitions of the closely related compounds SrFe{sub 2}As{sub 2} and EuFe{sub 2}As{sub 2} are characterised and the superconductors Sr{sub 1-x}K{sub x}Fe{sub 2}As{sub 2} and Ca{sub 1-x}Na{sub x}Fe{sub 2}As{sub 2} are examined for magnetic and phononic excitations. In Chapter 10, the redetermined crystal structure of the superconductor Fe(Se{sub 1-x}Te{sub x}) (11-type) is presented from a chemist's point of view. Chapters 11 - 14 look into the superconducting and non-superconducting iron arsenides of more complex structural families (32522-type and 21311-type). Therein, crystallographic and magnetic details of Sr{sub 3}Sc{sub 2}O{sub 5}Fe{sub 2}As{sub 2} are presented and Ba{sub 2}ScO{sub 3}FeAs and Sr{sub 2}CrO{sub 3}FeAs, the first two members of the new 21311-type are portrayed. Sr{sub 2}CrO{sub 3}FeAs is looked at in close detail with various methods, so e.g. the spin structure of the magnetically ordered compound is solved and a possible reason for the absence of superconductivity in this compound

  20. Targeting Iron Deficiency Anemia in Heart Failure.

    Science.gov (United States)

    Saraon, Tajinderpal; Katz, Stuart D

    2016-01-01

    Iron deficiency is common in heart failure (HF) patients, and is associated with increased risk of adverse clinical outcomes. Clinical trials of intravenous iron supplementation in iron-deficient HF patients have demonstrated short-term improvement in functional capacity and quality of life. In some trials, the benefits of iron supplementation were independent of the hemoglobin levels. Additional investigations of iron supplementation are needed to characterize the mechanisms contributing to clinical benefit and long-term safety in HF.

  1. The Pharmacokinetics and Pharmacodynamics of Iron Preparations

    OpenAIRE

    Susanna Burckhardt; Peter Geisser

    2011-01-01

    Standard approaches are not appropriate when assessing pharmacokinetics of iron supplements due to the ubiquity of endogenous iron, its compartmentalized sites of action, and the complexity of the iron metabolism. The primary site of action of iron is the erythrocyte, and, in contrast to conventional drugs, no drug-receptor interaction takes place. Notably, the process of erythropoiesis, i.e., formation of new erythrocytes, takes 3−4 weeks. Accordingly, serum iron concentration and area under...

  2. Streamlining Iron and Steel Production

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Eliminating unproductive iron and steel facilities is vital to environmental protection and sustainable development of this industry The Chinese Government is once again shutting down unproductive plants in tune with its green policy and the march toward sustainable development.This time it’s the iron and steel industry to feel the brunt of the Chinese Government’s stringent measures. The deafening buzz of factory floors have

  3. Iron deficiency and cognitive functions

    OpenAIRE

    Jáuregui-Lobera I

    2014-01-01

    Ignacio Jáuregui-Lobera Department of Nutrition and Bromatology, Pablo de Olavide University, Seville, Spain Abstract: Micronutrient deficiencies, especially those related to iodine and iron, are linked to different cognitive impairments, as well as to potential long-term behavioral changes. Among the cognitive impairments caused by iron deficiency, those referring to attention span, intelligence, and sensory perception functions are mainly cited, as well as those associated with...

  4. Iron, Oxidative Stress and Gestational Diabetes

    Directory of Open Access Journals (Sweden)

    Taifeng Zhuang

    2014-09-01

    Full Text Available Both iron deficiency and hyperglycemia are highly prevalent globally for pregnant women. Iron supplementation is recommended during pregnancy to control iron deficiency. The purposes of the review are to assess the oxidative effects of iron supplementation and the potential relationship between iron nutrition and gestational diabetes. High doses of iron (~relative to 60 mg or more daily for adult humans can induce lipid peroxidation in vitro and in animal studies. Pharmaceutical doses of iron supplements (e.g., 10× RDA or more for oral supplements or direct iron supplementation via injection or addition to the cell culture medium for a short or long duration will induce DNA damage. Higher heme-iron intake or iron status measured by various biomarkers, especially serum ferritin, might contribute to greater risk of gestational diabetes, which may be mediated by iron oxidative stress though lipid oxidation and/or DNA damage. However, information is lacking about the effect of low dose iron supplementation (≤60 mg daily on lipid peroxidation, DNA damage and gestational diabetes. Randomized trials of low-dose iron supplementation (≤60 mg daily for pregnant women are warranted to test the relationship between iron oxidative stress and insulin resistance/gestational diabetes, especially for iron-replete women.

  5. Maximum stellar iron core mass

    Indian Academy of Sciences (India)

    F W Giacobbe

    2003-03-01

    An analytical method of estimating the mass of a stellar iron core, just prior to core collapse, is described in this paper. The method employed depends, in part, upon an estimate of the true relativistic mass increase experienced by electrons within a highly compressed iron core, just prior to core collapse, and is significantly different from a more typical Chandrasekhar mass limit approach. This technique produced a maximum stellar iron core mass value of 2.69 × 1030 kg (1.35 solar masses). This mass value is very near to the typical mass values found for neutron stars in a recent survey of actual neutron star masses. Although slightly lower and higher neutron star masses may also be found, lower mass neutron stars are believed to be formed as a result of enhanced iron core compression due to the weight of non-ferrous matter overlying the iron cores within large stars. And, higher mass neutron stars are likely to be formed as a result of fallback or accretion of additional matter after an initial collapse event involving an iron core having a mass no greater than 2.69 × 1030 kg.

  6. [Genetics of hereditary iron overload].

    Science.gov (United States)

    Le Gall, Jean-Yves; Jouanolle, Anne-Marie; Fergelot, Patricia; Mosser, Jean; David, Véronique

    2004-01-01

    The classification of hereditary abnormalities of iron metabolism was recently expanded and diversified. Genetic hemochromatosis now corresponds to six diseases, namely classical hemochromatosis HFE 1; juvenile hemochromatosis HFE 2 due to mutations in an unidentified gene on chromosome 1; hemochromatosis HFE 3 due to mutations in the transferrin receptor 2 (TfR2); hemochromatosis HFE 4 caused by a mutation in the H subunit of ferritin; and hemochromatosis HFE 6 whose gene is hepcidine (HAMP). Systemic iron overload is also associated with aceruloplasminemia, atransferrinemia and the "Gracile" syndrome caused by mutations in BCS1L. The genes responsible for neonatal and African forms of iron overload are unknown. Other genetic diseases are due to localized iron overload: Friedreich's ataxia results from the expansion of triple nucleotide repeats within the frataxin (FRDA) gene; two forms of X-linked sideroblastic anemia are due to mutations within the delta aminolevulinate synthetase (ALAS 2) or ABC-7 genes; Hallervorden-Spatz syndrome is caused by a pantothenate kinase 2 gene (PANK-2) defect; neuroferritinopathies; and hyperferritinemia--cataract syndrome due to a mutation within the L-ferritin gene. In addition to this wide range of genetic abnormalities, two other features characterize these iron disorders: 1) most are transmitted by an autosomal recessive mechanism, but some, including hemochromatosis type 4, have dominant transmission; and 2) most correspond to cytosolic iron accumulation while some, like Friedreich's ataxia, are disorders of mitochondrial metabolism.

  7. Ferritins: furnishing proteins with iron.

    Science.gov (United States)

    Bradley, Justin M; Le Brun, Nick E; Moore, Geoffrey R

    2016-03-01

    Ferritins are a superfamily of iron oxidation, storage and mineralization proteins found throughout the animal, plant, and microbial kingdoms. The majority of ferritins consist of 24 subunits that individually fold into 4-α-helix bundles and assemble in a highly symmetric manner to form an approximately spherical protein coat around a central cavity into which an iron-containing mineral can be formed. Channels through the coat at inter-subunit contact points facilitate passage of iron ions to and from the central cavity, and intrasubunit catalytic sites, called ferroxidase centers, drive Fe(2+) oxidation and O2 reduction. Though the different members of the superfamily share a common structure, there is often little amino acid sequence identity between them. Even where there is a high degree of sequence identity between two ferritins there can be major differences in how the proteins handle iron. In this review we describe some of the important structural features of ferritins and their mineralized iron cores, consider how iron might be released from ferritins, and examine in detail how three selected ferritins oxidise Fe(2+) to explore the mechanistic variations that exist amongst ferritins. We suggest that the mechanistic differences reflect differing evolutionary pressures on amino acid sequences, and that these differing pressures are a consequence of different primary functions for different ferritins.

  8. Management of Iron Deficiency Anemia

    Science.gov (United States)

    Jimenez, Kristine; Kulnigg-Dabsch, Stefanie

    2015-01-01

    Anemia affects one-fourth of the world’s population, and iron deficiency is the predominant cause. Anemia is associated with chronic fatigue, impaired cognitive function, and diminished well-being. Patients with iron deficiency anemia of unknown etiology are frequently referred to a gastroenterologist because in the majority of cases the condition has a gastrointestinal origin. Proper management improves quality of life, alleviates the symptoms of iron deficiency, and reduces the need for blood transfusions. Treatment options include oral and intravenous iron therapy; however, the efficacy of oral iron is limited in certain gastrointestinal conditions, such as inflammatory bowel disease, celiac disease, and autoimmune gastritis. This article provides a critical summary of the diagnosis and treatment of iron deficiency anemia. In addition, it includes a management algorithm that can help the clinician determine which patients are in need of further gastrointestinal evaluation. This facilitates the identification and treatment of the underlying condition and avoids the unnecessary use of invasive methods and their associated risks. PMID:27099596

  9. Host iron status and iron supplementation mediate susceptibility to erythrocytic stage Plasmodium falciparum.

    Science.gov (United States)

    Clark, Martha A; Goheen, Morgan M; Fulford, Anthony; Prentice, Andrew M; Elnagheeb, Marwa A; Patel, Jaymin; Fisher, Nancy; Taylor, Steve M; Kasthuri, Raj S; Cerami, Carla

    2014-07-25

    Iron deficiency and malaria have similar global distributions, and frequently co-exist in pregnant women and young children. Where both conditions are prevalent, iron supplementation is complicated by observations that iron deficiency anaemia protects against falciparum malaria, and that iron supplements increase susceptibility to clinically significant malaria, but the mechanisms remain obscure. Here, using an in vitro parasite culture system with erythrocytes from iron-deficient and replete human donors, we demonstrate that Plasmodium falciparum infects iron-deficient erythrocytes less efficiently. In addition, owing to merozoite preference for young erythrocytes, iron supplementation of iron-deficient individuals reverses the protective effects of iron deficiency. Our results provide experimental validation of field observations reporting protective effects of iron deficiency and harmful effects of iron administration on human malaria susceptibility. Because recovery from anaemia requires transient reticulocytosis, our findings imply that in malarious regions iron supplementation should be accompanied by effective measures to prevent falciparum malaria.

  10. In vitro bioavailability of iron from the heme analogue sodium iron chlorophyllin.

    Science.gov (United States)

    Miret, Silvia; Tascioglu, Serpil; van der Burg, Monique; Frenken, Leon; Klaffke, Werner

    2010-01-27

    The use of heme analogues from vegetable origin could provide an alternative iron source of potentially high bioavailability. Sodium iron chlorophyllin is a water-soluble semisynthetic chlorophyll derivative where the magnesium in the porphyrin ring has been substituted by iron. We have used an in vitro model that combines gastric and intestinal digestion followed by intestinal iron uptake in Caco-2 cells to determine the bioavailability of iron from sodium iron chlorophyllin. Our results demonstrate that sodium iron chlorophyllin is stable under simulated gastrointestinal conditions and is able to deliver bioavailable iron to Caco-2 cells. Similar to the heme, the bioavailability of iron from sodium iron chlorophyllin is dependent on the food matrix, and it was inhibited by calcium. Potentially, sodium iron chlorophyllin could be used as an iron fortificant from vegetable origin with high bioavailability.

  11. 49 CFR 192.487 - Remedial measures: Distribution lines other than cast iron or ductile iron lines.

    Science.gov (United States)

    2010-10-01

    ... cast iron or ductile iron lines. 192.487 Section 192.487 Transportation Other Regulations Relating to... iron or ductile iron lines. (a) General corrosion. Except for cast iron or ductile iron pipe, each... the purpose of this paragraph. (b) Localized corrosion pitting. Except for cast iron or ductile...

  12. Iron biofortification and homeostasis in transgenic cassava roots expressing an algal iron assimilatory protein, FEA1

    OpenAIRE

    2012-01-01

    We have engineered the starchy root crop cassava (Manihot esculenta) to express the Chlamydomonas reinhardtii iron assimilatory protein, FEA1, in roots to enhance its nutritional qualities. Iron levels in mature cassava storage roots were increased from 10 to 36 ppm in the highest iron accumulating transgenic lines. These iron levels are sufficient to meet the minimum daily requirement for iron in a 500 gm meal. Significantly, the expression of the FEA1 protein did not alter iron levels in l...

  13. The impact of maternal iron deficiency and iron deficiency anemia on child’s health

    OpenAIRE

    Abu-Ouf, Noran M.; Jan, Mohammed M.

    2015-01-01

    Iron deficiency anemia is extremely common, particularly in the developing world, reaching a state of global epidemic. Iron deficiency during pregnancy is one of the leading causes of anemia in infants and young children. Many women go through the entire pregnancy without attaining the minimum required intake of iron. This review aims to determine the impact of maternal iron deficiency and iron deficiency anemia on infants and young children. Extensive literature review revealed that iron def...

  14. Mononuclear and Binuclear Ruthenium(II) Complexes Containing 2,2'-Bipyridine or 1,10-Phenanthroline and Pyrazole-3,5-Bis(benzimidazole). Synthesis, Structure, Isomerism, Spectroscopy, and Proton-Coupled Redox Activity.

    Science.gov (United States)

    Baitalik, Sujoy; Flörke, Ulrich; Nag, Kamalaksha

    1999-07-12

    A number of mixed-ligand mononuclear and binuclear ruthenium(II) complexes of composition [(bpy)(2)Ru(H(3)pzbzim)](ClO(4))(2).2H(2)O (1), [(phen)(2)Ru(H(3)pzbzim)](ClO(4))(2).3H(2)O (2), [(bpy)(2)Ru(H(2)pzbzim)Ru(bpy)(2)](ClO(4))(3).5H(2)O (3), [(phen)(2)Ru(H(2)pzbzim)Ru(phen)(2)](ClO(4))(3).4H(2)O (4), [(bpy)(2)Ru(H(2)pzbzim)Ru(phen)(2)](ClO(4))(3).4H(2)O (5), [(bpy)(2)Ru(pzbzim)Ru(bpy)(2)](ClO(4)).3H(2)O (6), and [(phen)(2)Ru(pzbzim)Ru(phen)(2)](ClO(4)).2H(2)O (7), where H(3)pzbzim = pyrazole-3,5-bis(benzimidazole), bpy = 2,2'-bipyridine, and phen = 1,10-phenanthroline, have been prepared and characterized. Complexes 3-5 isolated as mixtures of diastereoisomers have been separated by fractional recrystallization. In the cases of 3 and 4, the meso (LambdaDelta) and racemate (rac) (LambdaLambda, DeltaDelta) forms, and for 5, two enantiomeric pairs [(LambdaDelta, DeltaLambda) and (LambdaLambda, DeltaDelta)] have been obtained. These, as well as the meso and rac diastereoisomers of 6, have been characterized by (1)H and (13)C NMR spectroscopy. The crystal structure of the meso (LambdaDelta) form of 3 (C(57)H(53)N(14)Cl(3)O(17)Ru(2)) has been determined, which crystallizes in the monoclinic space group P2(1)/c with a = 11.672(2) Å, b = 41.696(9) Å, c = 12.871(2) Å, beta = 90.03(2)(o), and Z = 4. The acid-base and redox chemistry of the binuclear complexes has been studied over the pH range 1-12 in acetonitrile-water (3:2) medium. The equilibrium constants of the species involving protonation and deprotonation of the benzimidazole NH protons and the metal oxidation states covering +2 and +3 have been evaluated by spectrophotometric and cyclic voltammetric measurements. During spectrophotometric titrations of the complexes with cerium(IV), the metal-to-ligand charge transfer transitions are replaced by the newly generated ligand-to-metal charge transfer transition. The luminescence spectra of the complexes in solution (at 298 K) and in frozen glass (at 77 K) and

  15. Electrochemically fabricated zero-valent iron, iron-nickel, and iron-palladium nanowires for environmental remediation applications.

    Science.gov (United States)

    Yoo, B Y; Hernandez, S C; Koo, B; Rheem, Y; Myung, N V

    2007-01-01

    Monodisperse crystalline zero-valent iron, iron-nickel, iron-palladium nanowires were synthesised using template-directed electrodeposition methods. Prior to nanowire fabrication, alumina nanotemplates with controlled pore structure (e.g. pore diameter and porosity) were fabricated by anodising high purity aluminium foil in sulphuric acid. After fabrication of alumina nanotemplates, iron, iron-nickel and iron-palladium nanowires were electrodeposited within the pore structure. The dimensions of nanowires including diameter and length were precisely controlled by pore diameter of anodised alumina and deposition rate and time. The composition, crystal structure and orientation were controlled by adjusting electrodeposition parameters including applied current density and solution compositions.

  16. Iron deficiency and iron excess damage mitochondria and mitochondrial DNA in rats.

    Science.gov (United States)

    Walter, Patrick B; Knutson, Mitchell D; Paler-Martinez, Andres; Lee, Sonia; Xu, Yu; Viteri, Fernando E; Ames, Bruce N

    2002-02-19

    Approximately two billion people, mainly women and children, are iron deficient. Two studies examined the effects of iron deficiency and supplementation on rats. In study 1, mitochondrial functional parameters and mitochondrial DNA (mtDNA) damage were assayed in iron-deficient (mitochondrial respiratory control ratios and increased levels of oxidants in polymorphonuclear-leukocytes, as assayed by dichlorofluorescein (P mitochondrial malfunction. Although excess iron has been known to cause oxidative damage, the observation of oxidant-induced damage to mitochondria from iron deficiency has been unrecognized previously. Untreated iron deficiency, as well as excessive-iron supplementation, are deleterious and emphasize the importance of maintaining optimal iron intake.

  17. Hepcidin: regulation of the master iron regulator

    Science.gov (United States)

    Rishi, Gautam; Wallace, Daniel F.; Subramaniam, V. Nathan

    2015-01-01

    Iron, an essential nutrient, is required for many diverse biological processes. The absence of a defined pathway to excrete excess iron makes it essential for the body to regulate the amount of iron absorbed; a deficiency could lead to iron deficiency and an excess to iron overload and associated disorders such as anaemia and haemochromatosis respectively. This regulation is mediated by the iron-regulatory hormone hepcidin. Hepcidin binds to the only known iron export protein, ferroportin (FPN), inducing its internalization and degradation, thus limiting the amount of iron released into the blood. The major factors that are implicated in hepcidin regulation include iron stores, hypoxia, inflammation and erythropoiesis. The present review summarizes our present knowledge about the molecular mechanisms and signalling pathways contributing to hepcidin regulation by these factors. PMID:26182354

  18. Shigella Iron Acquisition Systems and their Regulation.

    Science.gov (United States)

    Wei, Yahan; Murphy, Erin R

    2016-01-01

    Survival of Shigella within the host is strictly dependent on the ability of the pathogen to acquire essential nutrients, such as iron. As an innate immune defense against invading pathogens, the level of bio-available iron within the human host is maintained at exceeding low levels, by sequestration of the element within heme and other host iron-binding compounds. In response to sequestration mediated iron limitation, Shigella produce multiple iron-uptake systems that each function to facilitate the utilization of a specific host-associated source of nutrient iron. As a mechanism to balance the essential need for iron and the toxicity of the element when in excess, the production of bacterial iron acquisition systems is tightly regulated by a variety of molecular mechanisms. This review summarizes the current state of knowledge on the iron-uptake systems produced by Shigella species, their distribution within the genus, and the molecular mechanisms that regulate their production.

  19. Synthesis, structural characterization, solution behavior, and in vitro antiproliferative properties of a series of gold complexes with 2-(2'-pyridyl)benzimidazole as ligand: comparisons of gold(III) versus gold(I) and mononuclear versus binuclear derivatives.

    Science.gov (United States)

    Serratrice, Maria; Cinellu, Maria A; Maiore, Laura; Pilo, Maria; Zucca, Antonio; Gabbiani, Chiara; Guerri, Annalisa; Landini, Ida; Nobili, Stefania; Mini, Enrico; Messori, Luigi

    2012-03-05

    A variety of gold(III) and gold(I) derivatives of 2-(2'-pyridyl)benzimidazole (pbiH) were synthesized and fully characterized and their antiproliferative properties evaluated in a representative ovarian cancer cell line. The complexes include the mononuclear species [(pbi)AuX(2)] (X = Cl, 1; OAc, 2), [(pbiH)AuCl] (3), [(pbiH)Au(PPh(3))][PF(6)] (4-PF(6)), and [(pbi)Au(L)] (L = PPh(3), 5; TPA, 6), and the binuclear gold(I)/gold(I) and gold(I)/gold(III) derivatives [(PPh(3))(2)Au(2)(μ(2)-pbi)][PF(6)] (10-PF(6)), [ClAu(μ(3)-pbi)AuCl(2)] (7),and [(PPh(3))Au(μ(3)-pbi)AuX(2)][PF(6)] (X = Cl, 8-PF(6); OAc, 9-PF(6)). The molecular structures of 6, 7, and 10-PF(6) were determined by X-ray diffraction analysis. The chemical behavior of these compounds in solution was analyzed both by cyclic voltammetry in DMF and absorption UV-vis spectroscopy in an aqueous buffer. Overall, the stability of these gold compounds was found to be acceptable for the cellular studies. For all complexes, relevant antiproliferative activities in vitro were documented against A2780 human ovarian carcinoma cells, either resistant or sensitive to cisplatin, with IC(50) values falling in the low micromolar or even in the nanomolar range. The investigated gold compounds were found to overcome resistance to cisplatin to a large degree. Results are interpreted and discussed in the frame of current knowledge on cytotoxic and antitumor gold compounds.

  20. Binuclear copper(II), cobalt(II) and nickel(II) complexes of N1-ethyl-N2-(pyridin-2-yl) hydrazine-1,2-bis(carbothioamide): structural, spectral, pH-metric and biological studies.

    Science.gov (United States)

    El-Gammal, O A; Abu El-Reash, G M; El-Gamil, M M

    2012-10-01

    Binuclear Cu(II), Co(II) and Ni(II) complexes derived from N(1)-ethyl-N(2)-(pyridin-2-yl) hydrazine-1,2-bis(carbothioamide) (H(2)PET) have been prepared and characterized by elemental analysis, spectral (IR, UV-vis, EI mass, ESR and (1)HNMR) and magnetic measurements. The isolated complexes assigned the general formula, [M(HPET)(H(2)O)(n)Cl](2)·xH(2)O where M=Cu(II), Co(II) and Ni(II), n=2, 1, 0 and x=0, 0.5 and 0, respectively. IR data revealed that the ligand behaves as monobasic tridentate through (CN)(py), (C-S) and new azomethine, (NC)(∗) groups in the Co(II) complex but in Cu(II) complex, the ligand coordinate via both (CS) groups, one of them in thiol form as well as the new azomethine group. In Ni(II) complex, H(2)PET acts as NSNS monobasic tetradente via (CN)(py), (C-S), (CS) and the new azomethine, (NC)(∗) groups. An octahedral geometry is proposed for all complexes. pH- metric titration was carried out in 50% dioxane-water mixture at 298, 308 and 318 °K, respectively and the dissociation constant of the ligand as well as the stability constants of its complexes were evaluated. Also the kinetic and thermodynamic parameters for the different thermal decomposition steps of the complexes were determined by Coats-Redfern and Horowitz-Metzger methods. Moreover, the anti-oxidant, anti-hemolytic, and cytotoxic activities of the compounds have been tested.

  1. Antibacterial, antibiofilm and antioxidant screening of copper(II)-complexes with some S-alkyl derivatives of thiosalicylic acid. Crystal structure of the binuclear copper(II)-complex with S-propyl derivative of thiosalicylic acid

    Science.gov (United States)

    Bukonjić, Andriana M.; Tomović, Dušan Lj.; Nikolić, Miloš V.; Mijajlović, Marina Ž.; Jevtić, Verica V.; Ratković, Zoran R.; Novaković, Slađana B.; Bogdanović, Goran A.; Radojević, Ivana D.; Maksimović, Jovana Z.; Vasić, Sava M.; Čomić, Ljiljana R.; Trifunović, Srećko R.; Radić, Gordana P.

    2017-01-01

    The spectroscopically predicted structure of the obtained copper(II)-complex with S-propyl derivative of thiosalicylic acid was confirmed by X-ray structural study. The binuclear copper(II)-complex with S-propyl derivative of thiosalicylic acid crystallized in two polymorphic forms with main structural difference in the orientation of phenyl rings relative to corresponding carboxylate groups. The antibacterial activity was tested determining the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) by using microdilution method. The influence on bacterial biofilm formation was determined by tissue culture plate method. In general, the copper(II)-complexes manifested a selective and moderate activity. The most sensitive bacteria to the effects of Cu(II)-complexes was a clinical isolate of Pseudomonas aeruginosa. For this bacteria MIC and biofilm inhibitory concentration (BIC) values for all tested complexes were in the range or better than the positive control, doxycycline. Also, for the established biofilm of clinical isolate Staphylococcus aureus, BIC values for the copper(II)-complex with S-ethyl derivative of thiosalicylic acid,[Cu2(S-et-thiosal)4(H2O)2] (C3) and copper(II)-complex with S-butyl derivative of thiosalicylic acid, [Cu2(S-bu-thiosal)4(H2O)2] (C5) were in range or better than the positive control. All the complexes acted better against Gram-positive bacteria (Staphylococcus aureus and Staphylococcus aureus ATCC 25923) than Gram-negative bacteria (Proteus mirabilis ATCC 12453, Pseudomonas aeruginosa, and P. aeruginosa ATCC 27855). The complexes showed weak antioxidative properties tested by two methods (1,1-diphenyl-2-picrylhydrazyl (DPPH) and reducing power assay).

  2. Study of the manganese (II) manganese (III) complexes with quinaldic acid in aprotic medium, mononuclear and binuclear species produced under these conditions and possible formation of radical species upon oxidation or reduction of the ligand

    Energy Technology Data Exchange (ETDEWEB)

    Bodini, E.M.; Funes, M.M.; Valle, M.A. del; Arancibia, V. [Departamento de Quimica Analitica y Electroquimica, Facultad de Quimica, Universidad Catolica de Chile (Switzerland)

    1996-11-01

    The redox chemistry of the ligand Quinaldic acid (2-QA), its monoanion and its complexes with manganese (II) and manganese (III) has studied in dimethylsulphoxide using electrochemical, spectroscopic and magnetic measurements. The protonated ligand is reduce at -1.28 V vs SCE with the transfer of one equivalent of charge the resulting solution presents oxidation peaks at -0.02 V, +0.32 V and +1.14 V vs SCE which is indicative that both radical and dimeric species are involved in the oxidation processes. The combination of the monoanion of the ligand with Mn(II) in a 1:2 mole ratio forms a stable complex which presents a magnetic susceptibility of 5.90B.M. and conditional formation constant of 1.71 x 10``8 M``-2. Its oxidation at +0.76 V vs SCE yields a brown complex of Mn(III) with a magnetic susceptibility of 4.80 B.M. The voltammetric behaviour of the latter species indicates that is probably binuclear. This complex is reduced at +0.60 V vs SCE generating a Mn(II)-Mn(III) mixed-valance complex, and a second reduction at -0.40 V vs SCE regenerating the mononuclear Mn(II) complex. The mixed-valance complex decomposes quickly generating the corresponding Mn(II) and Mn(III) monomers. On the other hand, in the presence of this metal ion as counter-ion, both its +2 or +3 oxidation state, the monoanion of the ligand shows reduction processes that might lead to the stabilization of radical species. the voltammetric and spectroscopic characterization if these species is described. The results may be useful to the understanding of the charge transfer mechanism in biological systems. (Author) 26 refs.

  3. Retinal iron homeostasis in health and disease

    Directory of Open Access Journals (Sweden)

    Delu eSong

    2013-06-01

    Full Text Available Iron is essential for life, but excess iron can be toxic. As a potent free radical creator, iron generates hydroxyl radicals leading to significant oxidative stress. Since iron is not excreted from the body, it accumulates with age in tissues, including the retina, predisposing to age-related oxidative insult. Both hereditary and acquired retinal diseases are associated with increased iron levels. For example, retinal degenerations have been found in hereditary iron overload disorders, like aceruloplasminemia, Friedreich’s ataxia, and pantothenate kinase-associated neurodegeneration. Similarly, mice with targeted mutation of the iron exporter ceruloplasmin and its homolog hephaestin showed age-related retinal iron accumulation and retinal degeneration with features resembling human age-related macular degeneration (AMD. Post mortem AMD eyes have increased levels of iron in retina compared to age-matched healthy donors. Iron accumulation in AMD is likely to result, in part, from inflammation, hypoxia, and oxidative stress, all of which can cause iron dysregulation. Fortunately, it has been demonstrated by in vitro and in vivo studies that iron in the retinal pigment epithelium and retina is chelatable. Iron chelation protects photoreceptors and retinal pigment epithelial cells (RPE in a variety of mouse models. This has therapeutic potential for diminishing iron-induced oxidative damage to prevent or treat AMD.

  4. Fatal anaphylactic reaction to iron sucrose in pregnancy

    Directory of Open Access Journals (Sweden)

    Ajay Mishra

    2013-01-01

    Full Text Available Iron-deficiency anemia in pregnancy can have serious deleterious effects for both mother and fetus. Parenteral iron therapy in iron-deficiency anemia is recommended in patients where oral iron therapy is ineffective due to malabsorption states and non-compliance. Compared to oral iron therapy, intravenous iron results in much more rapid resolution of iron-deficiency anemia with minimal adverse reactions. Iron sucrose has a favorable safety profile and is an alternative to other forms of parenteral iron therapy in correction of iron stores depletion. Immune mechanisms and iron agent releasing bioactive, partially unbound iron into the circulation, resulting in oxidative stress appears to cause severe adverse reactions. Although iron sucrose has a favorable safety profile in comparison to other parenteral iron preparations, this report highlights a fatal anaphylactic shock to iron sucrose in a pregnant woman with severe iron deficiency non-compliant to oral iron therapy.

  5. Colour Metallography of Cast Iron

    Institute of Scientific and Technical Information of China (English)

    By Zhou Jiyang; Professor

    2011-01-01

    5.5 Eutectic crystallisation of white iron When undercooled below the eutectic line ECF in the Fe-C phase diagram,liquid iron will start eutectic transformation (crystallization):eutectic liquid → cementite + austenite.Eutectic crystallisation is an important stage during the crystallization of white iron.At this stage,the nucleation and growth of eutectic cells (consisting of carbide or cementite + austenite) occur.The carbide in eutectic cells (or eutectic carbide) is the main hard and brittle phase structure which has an important effect on the properties of white iron.If there is no primary carbide in the structure,the effect of eutectic carbide is more prominent.5.5.1 Thermodynamics and kinetics of eutectic crystallisationWhether a eutectic melt follows the meta-stable system to crystallise as carbide + austenite,or follows the stable system to crystallise as graphite + austenite eutectic,is dependent on the nucleation and growth of the two high carbon phases (carbide and graphite),namely,on thermodynamic and kinetic conditions.Figure 5-23 shows the comparison of thermodynamic driving forces of the two eutectics.The two lines in the lower section of the figure represent the free energy of the two eutectics respectively and GL is the free energy of the undercooled iron melt.It is easy to see that the iron melt has the highest free energy and the graphiteaustenite has the lowest free energy;so,following a stable system,the thermodynamic condition favours the crystallisation of graphite-austenite eutectic from the iron melt.

  6. Accelerated dissolution of iron oxides in ice

    Directory of Open Access Journals (Sweden)

    D. Jeong

    2012-11-01

    Full Text Available Iron dissolution from mineral dusts and soil particles is vital as a source of bioavailable iron in various environmental media. In this work, the dissolution of iron oxide particles trapped in ice was investigated as a new pathway of iron supply. The dissolution experiments were carried out in the absence and presence of various organic complexing ligands under dark condition. In acidic pH conditions (pH 2, 3, and 4, the dissolution of iron oxides was greatly enhanced in the ice phase compared to that in water. The dissolved iron was mainly in the ferric form, which indicates that the dissolution is not a reductive process. The extent of dissolved iron was greatly affected by the kind of organic complexing ligands and the surface area of iron oxides. The iron dissolution was most pronounced with high surface area iron oxides and in the presence of strong iron binding ligands. The enhanced dissolution of iron oxides in ice is mainly ascribed to the "freeze concentration effect", which concentrates iron oxide particles, organic ligands, and protons in the liquid like ice grain boundary region and accelerates the dissolution of iron oxides. The ice-enhanced dissolution effect gradually decreased when decreasing the freezing temperature from −10 to −196 °C, which implies that the presence and formation of the liquid-like ice grain boundary region play a critical role. The proposed phenomenon of enhanced dissolution of iron oxides in ice may provide a new pathway of bioavailable iron production. The frozen atmospheric ice with iron-containing dust particles in the upper atmosphere thaws upon descending and may provide bioavailable iron upon deposition onto the ocean surface.

  7. Accelerated dissolution of iron oxides in ice

    Directory of Open Access Journals (Sweden)

    D. Jeong

    2012-08-01

    Full Text Available Iron dissolution from mineral dusts and soil particles is vital as a source of bioavailable iron in various environmental media. In this work, the dissolution of iron oxide particles trapped in ice was investigated as a~new pathway of iron supply. The dissolution experiments were carried out in the absence and presence of various organic complexing ligands under dark condition. In acidic pH conditions (pH 2, 3, and 4, the dissolution of iron oxides was greatly enhanced in the ice phase compared to that in water. The dissolved iron was mainly in the ferric form, which indicates that the dissolution is not a reductive process. The extent of dissolved iron was greatly affected by the kind of organic complexing ligands and the type of iron oxides. The iron dissolution was most pronounced with high surface area iron oxides and in the presence of strong iron binding ligands. The enhanced dissolution of iron oxides in ice is mainly ascribed to the "freeze concentration effect", which concentrates iron oxide particles, organic ligands, and protons in the liquid-like ice grain boundary region and accelerates the dissolution of iron oxides. The ice-enhanced dissolution effect gradually decreased when decreasing the freezing temperature from −10 °C to −196 °C, which implies that the presence and formation of the liquid-like ice grain boundary region play a critical role. The proposed phenomenon of enhanced dissolution of iron oxides in ice may provide a new pathway of bioavailable iron production. The frozen atmospheric ice with iron-containing dust particles in the upper atmosphere thaws upon descending and may provide bioavailable iron upon deposition onto the ocean surface.

  8. BESITY AND IRON DEFICIENCY. ONE MORE COMORBIDITY?

    Directory of Open Access Journals (Sweden)

    L. I. L.I. Dvoretsky

    2015-01-01

    Full Text Available Iron defi ciency is one of comorbidity in patients with obesity, which allows you to select a particular phenotype (“iron defi ciency” obesity. There is strong evidence of the pathogenetic link between iron defi ciency and the presence of systemic infl ammation associated with obesity. Data on the frequency and pathogenic form of anemia ( iron defi ciency or anemia of chronic disease , obesity are not unique. Further research of iron status in obese patients is needed to decide on the feasibility and methods of correction of disorders of iron metabolism , in particular in the preparation of patients for bariatric surgery.

  9. Cast iron - a predictable material

    Directory of Open Access Journals (Sweden)

    Jorg C. Sturm

    2011-02-01

    Full Text Available High strength compacted graphite iron (CGI or alloyed cast iron components are substituting previously used non-ferrous castings in automotive power train applications. The mechanical engineering industry has recognized the value in substituting forged or welded structures with stiff and light-weight cast iron castings. New products such as wind turbines have opened new markets for an entire suite of highly reliable ductile iron cast components. During the last 20 years, casting process simulation has developed from predicting hot spots and solidification to an integral assessment tool for foundries for the entire manufacturing route of castings. The support of the feeding related layout of the casting is still one of the most important duties for casting process simulation. Depending on the alloy poured, different feeding behaviors and self-feeding capabilities need to be considered to provide a defect free casting. Therefore, it is not enough to base the prediction of shrinkage defects solely on hot spots derived from temperature fields. To be able to quantitatively predict these defects, solidification simulation had to be combined with density and mass transport calculations, in order to evaluate the impact of the solidification morphology on the feeding behavior as well as to consider alloy dependent feeding ranges. For cast iron foundries, the use of casting process simulation has become an important instrument to predict the robustness and reliability of their processes, especially since the influence of alloying elements, melting practice and metallurgy need to be considered to quantify the special shrinkage and solidification behavior of cast iron. This allows the prediction of local structures, phases and ultimately the local mechanical properties of cast irons, to asses casting quality in the foundry but also to make use of this quantitative information during design of the casting. Casting quality issues related to thermally driven

  10. Iron isotope composition of some Archean and Proterozoic iron formations

    Science.gov (United States)

    Planavsky, Noah; Rouxel, Olivier J.; Bekker, Andrey; Hofmann, Axel; Little, Crispin T. S.; Lyons, Timothy W.

    2012-03-01

    Fe isotopes can provide new insight into redox-dependent biogeochemical processes. Precambrian iron formations (IF) are deserving targets for Fe isotope studies because they are composed predominantly of authigenic Fe phases and record a period of unprecedented iron deposition in Earth's history. We present Fe isotope data for bulk samples from 24 Archean and Proterozoic IF and eight Phanerozoic Fe oxide-rich deposits. These data reveal that many Archean and early Paleoproterozoic iron formations were a sink for isotopically heavy Fe, in contrast to later Proterozoic and Phanerozoic Fe oxide-rich rocks. The positive δ56Fe values in IF are best explained by delivery of particulate ferric oxides formed in the water column to the sediment-water interface. Because IF are a net sink for isotopically heavy Fe, there must be a corresponding pool of isotopically light Fe in the sedimentary record. Earlier work suggested that Archean pyritic black shales were an important part of this light sink before 2.35 billion years ago (Ga). It is therefore likely that the persistently and anomalously low δ56Fe values in shales are linked with the deposition of isotopically heavy Fe in IF in the deeper parts of basins. IF deposition produced a residual isotopically light dissolved Fe pool that was captured by pyritic Fe in shales. Local dissimilatory Fe reduction in porewater and associated diagenetic reactions resulting in pyrite and carbonate precipitation may have further enhanced Fe isotope heterogeneity in marine sediments, and an 'iron shuttle' may have transported isotopically light Fe from shelf sediments to the basin. Nevertheless, water-column processing of hydrothermally delivered Fe likely had the strongest influence on the bulk iron isotope composition of Archean and Paleoproterozoic iron formations and other marine sediments.

  11. What´s cheapest, intravenous iron sucrose- or intravenous iron carboxymaltose treatment in IBD patients?

    DEFF Research Database (Denmark)

    Bager, Palle; Dahlerup, Jens Frederik

    for a total of iron-dose was to 233€ to reduce the numbers of infusion from 7 till 2.    Conclusion: The cost of choosing iron carboxymaltose rather than iron sucrose in treatment of iron deficiency in IBD differs depending of the economic perspective chosen. Only the Budget Impact Analysis showed iron......  What´s cheapest, intravenous iron sucrose- or intravenous iron carboxymaltose treatment in IBD patients? It dependent on the economic evaluation perspective!   Aim: To evaluate the health care cost for intravenous iron sucrose (Venofer®, Vifor) and intravenous iron carboxymaltose (Ferinject......®, Vifor) treatment to IBD patients in an outpatient setting.   Background: Intravenous iron sucrose can be given as a maximum of 200 mg Fe++ per infusion vs. intravenous iron carboxymaltose that can be given as a maximum of 1000 mg Fe++ in a single infusion leading to fewer infusions and visits. The drug...

  12. Inoculation Effects of Cast Iron

    Directory of Open Access Journals (Sweden)

    E. Fraś

    2012-12-01

    Full Text Available The paper presents a solidification sequence of graphite eutectic cells of A and D types, as well as globular and cementite eutectics. The morphology of eutectic cells in cast iron, the equations for their growth and the distances between the graphite precipitations in A and D eutectic types were analyzed. It is observed a critical eutectic growth rate at which one type of eutectic transformed into another. A mathematical formula was derived that combined the maximum degree of undercooling, the cooling rate of cast iron, eutectic cell count and the eutectic growth rate. One type of eutectic structure turned smoothly into the other at a particular transition rate, transformation temperature and transformational eutectic cell count. Inoculation of cast iron increased the number of eutectic cells with flake graphite and the graphite nodule count in ductile iron, while reducing the undercooling. An increase in intensity of inoculation caused a smooth transition from a cementite eutectic structure to a mixture of cementite and D type eutectic structure, then to a mixture of D and A types of eutectics up to the presence of only the A type of eutectic structure. Moreover, the mechanism of inoculation of cast iron was studied.

  13. Combination therapies in iron chelation

    Directory of Open Access Journals (Sweden)

    Raffaella Origa

    2014-12-01

    Full Text Available The availability of oral iron chelators and new non-invasive methods for early detection and treatment of iron overload, have significantly improved the life expectancy and quality of life of patients with b thalassemia major. However, monotherapy is not effective in all patients for a variety of reasons. We analyzed the most relevant reports recently published on alternating or combined chelation therapies in thalassemia major with special attention to safety aspects and to their effects in terms of reduction of iron overload in different organs, improvement of complications, and survival. When adverse effects, such as gastrointestinal upset with deferasirox or infusional site reactions with deferoxamine are not tolerable and organ iron is in an acceptable range, alternating use of two chelators (drugs taken sequentially on different days, but not taken on the same day together may be a winning choice. The association deferiprone and deferoxamine should be the first choice in case of heart failure and when dangerously high levels of cardiac iron exist. Further research regarding the safety and efficacy of the most appealing combination treatment, deferiprone and deferasirox, is needed before recommendations for routine clinical practice can be made.

  14. Graphite Formation in Cast Iron

    Science.gov (United States)

    Stefanescu, D. M.

    1985-01-01

    In the first phase of the project it was proven that by changing the ratio between the thermal gradient and the growth rate for commercial cast iron samples solidifying in a Bridgman type furnace, it is possible to produce all types of graphite structures, from flake to spheroidal, and all types of matrices, from ferritic to white at a certain given level of cerium. KC-135 flight experiments have shown that in a low-gravity environment, no flotation occurs even in spheroidal graphite cast irons with carbon equivalent as high as 5%, while extensive graphite flotation occurred in both flake and spheroidal graphite cast irons, in high carbon samples solidified in a high gravity environment. This opens the way for production of iron-carbon composite materials, with high carbon content (e.g., 10%) in a low gravity environment. By using KC-135 flights, the influence of some basic elements on the solidification of cast iron will be studied. The mechanism of flake to spheroidal graphite transition will be studied, by using quenching experiments at both low and one gravity for different G/R ratios.

  15. Alginate-Iron Speciation and Its Effect on In Vitro Cellular Iron Metabolism.

    Directory of Open Access Journals (Sweden)

    Richard D Horniblow

    Full Text Available Alginates are a class of biopolymers with known iron binding properties which are routinely used in the fabrication of iron-oxide nanoparticles. In addition, alginates have been implicated in influencing human iron absorption. However, the synthesis of iron oxide nanoparticles employs non-physiological pH conditions and whether nanoparticle formation in vivo is responsible for influencing cellular iron metabolism is unclear. Thus the aims of this study were to determine how alginate and iron interact at gastric-comparable pH conditions and how this influences iron metabolism. Employing a range of spectroscopic techniques under physiological conditions alginate-iron complexation was confirmed and, in conjunction with aberration corrected scanning transmission electron microscopy, nanoparticles were observed. The results infer a nucleation-type model of iron binding whereby alginate is templating the condensation of iron-hydroxide complexes to form iron oxide centred nanoparticles. The interaction of alginate and iron at a cellular level was found to decrease cellular iron acquisition by 37% (p < 0.05 and in combination with confocal microscopy the alginate inhibits cellular iron transport through extracellular iron chelation with the resulting complexes not internalised. These results infer alginate as being useful in the chelation of excess iron, especially in the context of inflammatory bowel disease and colorectal cancer where excess unabsorbed luminal iron is thought to be a driver of disease.

  16. Direct Biohydrometallurgical Extraction of Iron from Ore

    Energy Technology Data Exchange (ETDEWEB)

    T.C. Eisele

    2005-10-01

    A completely novel approach to iron extraction was investigated, based on reductive leaching of iron by anaerobic bacteria. Microorganisms were collected from an anaerobic bog where natural seepage of dissolved iron was observed. This mixed culture was used to reduce insoluble iron in a magnetite ore to the soluble ferrous (Fe{sup +2}) state. While dissolution rates were slow, concentrations of dissolved iron as high as 3487 mg/l could be reached if sufficient time was allowed. A factorial study of the effects of trace nutrients and different forms of organic matter indicated that the best dissolution rates and highest dissolved iron concentrations were achieved using soluble carbohydrate (sucrose) as the bacterial food source, and that nutrients other than nitrogen, phosphorus, potassium, sodium, and acetate were not necessary. A key factor in reaching high levels of dissolved iron was maintaining a high level of carbon dioxide in solution, since the solubility of iron carbonates increases markedly as the quantity of dissolved carbon dioxide increases. Once the iron is dissolved, it has been demonstrated that the ferrous iron can then be electroplated from solution, provided that the concentration of iron is sufficiently high and the hydrogen ion concentration is sufficiently low. However, if the leaching solution is electrolyzed directly, organic matter precipitates at the cathode along with the metallic iron. To prevent this problem, the ferrous iron should be separated from the bulk solution in a more concentrated, purified form. One route to accomplishing this is to take advantage of the change in solubility of ferrous iron as a function of carbon dioxide concentration. By cycling the concentration of carbon dioxide in solution, it is possible to produce an iron-rich concentrate that should be suitable for electrolysis. This represents the first viable hydrometallurgical method for leaching iron directly from ore and producing metallic iron.

  17. Tetranuclear iron(III) complexes of an octadentate pyridine-carboxylate ligand and their catalytic activity in alkane oxidation by hydrogen peroxide.

    Science.gov (United States)

    Gutkina, Elena A; Trukhan, Vladimir M; Pierpont, Cortlandt G; Mkoyan, Shaen; Strelets, Vladimir V; Nordlander, Ebbe; Shteinman, Albert A

    2006-01-21

    oxidation catalysts. Catalytic reactions carried out with alkane substrate molecules and hydrogen peroxide predominantly gave alcohols. High stereospecificity in the oxidation of cis-1,2-dimethylcyclohexane supports the metal-based molecular mechanism of O-insertion into C-H bonds postulated for non-heme iron enzymes such as methane monooxygenase.

  18. Missing Fe: hydrogenated iron nanoparticles

    CERN Document Server

    Bilalbegovic, G; Mohacek-Grosev, V

    2016-01-01

    Although it was found that the FeH lines exist in the spectra of some stars, none of the spectral features in the ISM have been assigned to this molecule. We suggest that iron atoms interact with hydrogen and produce Fe-H nanoparticles which sometimes contain many H atoms. We calculate infrared spectra of hydrogenated iron nanoparticles using density functional theory methods and find broad, overlapping bands. Desorption of H2 could induce spinning of these small Fe-H dust grains. Some of hydrogenated iron nanoparticles posses magnetic and electric moments and should interact with electromagnetic fields in the ISM. Fe_nH_m nanoparticles could contribute to the polarization of the ISM and the anomalous microwave emission. We discuss the conditions required to form FeH and Fe_nH_m in the ISM.

  19. Missing Fe: hydrogenated iron nanoparticles

    Science.gov (United States)

    Bilalbegović, G.; Maksimović, A.; Mohaček-Grošev, V.

    2017-03-01

    Although it was found that the FeH lines exist in the spectra of some stars, none of the spectral features in the interstellar medium (ISM) have been assigned to this molecule. We suggest that iron atoms interact with hydrogen and produce Fe-H nanoparticles which sometimes contain many H atoms. We calculate infrared spectra of hydrogenated iron nanoparticles using density functional theory methods and find broad, overlapping bands. Desorption of H2 could induce spinning of these small Fe-H dust grains. Some of hydrogenated iron nanoparticles possess magnetic and electric moments and should interact with electromagnetic fields in the ISM. FenHm nanoparticles could contribute to the polarization of the ISM and the anomalous microwave emission. We discuss the conditions required to form FeH and FenHm in the ISM.

  20. Estimation of dietary iron bioavailability from food iron intake and iron status.

    Directory of Open Access Journals (Sweden)

    Jack R Dainty

    Full Text Available Currently there are no satisfactory methods for estimating dietary iron absorption (bioavailability at a population level, but this is essential for deriving dietary reference values using the factorial approach. The aim of this work was to develop a novel approach for estimating dietary iron absorption using a population sample from a sub-section of the UK National Diet and Nutrition Survey (NDNS. Data were analyzed in 873 subjects from the 2000-2001 adult cohort of the NDNS, for whom both dietary intake data and hematological measures (hemoglobin and serum ferritin (SF concentrations were available. There were 495 men aged 19-64 y (mean age 42.7±12.1 y and 378 pre-menopausal women (mean age 35.7±8.2 y. Individual dietary iron requirements were estimated using the Institute of Medicine calculations. A full probability approach was then applied to estimate the prevalence of dietary intakes that were insufficient to meet the needs of the men and women separately, based on their estimated daily iron intake and a series of absorption values ranging from 1-40%. The prevalence of SF concentrations below selected cut-off values (indicating that absorption was not high enough to maintain iron stores was derived from individual SF concentrations. An estimate of dietary iron absorption required to maintain specified SF values was then calculated by matching the observed prevalence of insufficiency with the prevalence predicted for the series of absorption estimates. Mean daily dietary iron intakes were 13.5 mg for men and 9.8 mg for women. Mean calculated dietary absorption was 8% in men (50th percentile for SF 85 µg/L and 17% in women (50th percentile for SF 38 µg/L. At a ferritin level of 45 µg/L estimated absorption was similar in men (14% and women (13%. This new method can be used to calculate dietary iron absorption at a population level using data describing total iron intake and SF concentration.

  1. Iron Chelation and Multiple Sclerosis

    Directory of Open Access Journals (Sweden)

    Kelsey J. Weigel

    2014-01-01

    Full Text Available Histochemical and MRI studies have demonstrated that MS (multiple sclerosis patients have abnormal deposition of iron in both gray and white matter structures. Data is emerging indicating that this iron could partake in pathogenesis by various mechanisms, e.g., promoting the production of reactive oxygen species and enhancing the production of proinflammatory cytokines. Iron chelation therapy could be a viable strategy to block iron-related pathological events or it can confer cellular protection by stabilizing hypoxia inducible factor 1α, a transcription factor that normally responds to hypoxic conditions. Iron chelation has been shown to protect against disease progression and/or limit iron accumulation in some neurological disorders or their experimental models. Data from studies that administered a chelator to animals with experimental autoimmune encephalomyelitis, a model of MS, support the rationale for examining this treatment approach in MS. Preliminary clinical studies have been performed in MS patients using deferoxamine. Although some side effects were observed, the large majority of patients were able to tolerate the arduous administration regimen, i.e., 6–8 h of subcutaneous infusion, and all side effects resolved upon discontinuation of treatment. Importantly, these preliminary studies did not identify a disqualifying event for this experimental approach. More recently developed chelators, deferasirox and deferiprone, are more desirable for possible use in MS given their oral administration, and importantly, deferiprone can cross the blood–brain barrier. However, experiences from other conditions indicate that the potential for adverse events during chelation therapy necessitates close patient monitoring and a carefully considered administration regimen.

  2. Disassembling iron availability to phytoplankton

    Directory of Open Access Journals (Sweden)

    Yeala eShaked

    2012-04-01

    Full Text Available The bioavailability of iron to microorganisms and its underlying mechanisms have far reaching repercussions to many natural systems and diverse fields of research, including ocean biogeochemistry, carbon cycling and climate, harmful algal blooms, soil and plant research, bioremediation, pathogenesis and medicine. Within the framework of ocean sciences, short supply and restricted bioavailability of Fe to phytoplankton is thought to limit primary production and curtail atmospheric CO2 drawdown in vast ocean regions. Yet a clear-cut definition of bioavailability remains elusive, with elements of iron speciation and kinetics, phytoplankton physiology, light, temperature and microbial interactions, to name a few, all intricately intertwined into this concept. Here, in a synthesis of published and new data, we attempt to disassemble the complex concept of iron bioavailability to phytoplankton by individually exploring some of its facets. We distinguish between the fundamentals of bioavailability - the acquisition of Fe-substrate by phytoplankton - and added levels of complexity involving interactions among organisms, iron and ecosystem processes. We first examine how phytoplankton acquire free and organically-bound iron, drawing attention to the pervasiveness of the reductive uptake pathway in both prokaryotes and eukaryotes. Turning to acquisition rates, we propose to view the availability of various Fe-substrates to phytoplankton as spectrum rather than an absolute all or nothing. We then demonstrate the use of uptake rate constants to make comparisons across different studies, organisms, Fe compounds and environments, and for gauging the contribution of various Fe substrates to phytoplankton growth in situ. Last, we describe the influence of aquatic microorganisms on iron chemistry and fate by way of organic complexation and bio-mediated redox transformations and examine the bioavailability of these bio-modified Fe species.

  3. Disassembling iron availability to phytoplankton.

    Science.gov (United States)

    Shaked, Yeala; Lis, Hagar

    2012-01-01

    The bioavailability of iron to microorganisms and its underlying mechanisms have far reaching repercussions to many natural systems and diverse fields of research, including ocean biogeochemistry, carbon cycling and climate, harmful algal blooms, soil and plant research, bioremediation, pathogenesis, and medicine. Within the framework of ocean sciences, short supply and restricted bioavailability of Fe to phytoplankton is thought to limit primary production and curtail atmospheric CO(2) drawdown in vast ocean regions. Yet a clear-cut definition of bioavailability remains elusive, with elements of iron speciation and kinetics, phytoplankton physiology, light, temperature, and microbial interactions, to name a few, all intricately intertwined into this concept. Here, in a synthesis of published and new data, we attempt to disassemble the complex concept of iron bioavailability to phytoplankton by individually exploring some of its facets. We distinguish between the fundamentals of bioavailability - the acquisition of Fe-substrate by phytoplankton - and added levels of complexity involving interactions among organisms, iron, and ecosystem processes. We first examine how phytoplankton acquire free and organically bound iron, drawing attention to the pervasiveness of the reductive uptake pathway in both prokaryotic and eukaryotic autotrophs. Turning to acquisition rates, we propose to view the availability of various Fe-substrates to phytoplankton as a spectrum rather than an absolute "all or nothing." We then demonstrate the use of uptake rate constants to make comparisons across different studies, organisms, Fe-compounds, and environments, and for gaging the contribution of various Fe-substrates to phytoplankton growth in situ. Last, we describe the influence of aquatic microorganisms on iron chemistry and fate by way of organic complexation and bio-mediated redox transformations and examine the bioavailability of these bio-modified Fe species.

  4. [Iron concentration and acceptation of yoghurt prepared in casting iron pots (iron migration and acceptation of yogurt)].

    Science.gov (United States)

    Quintaes, Késia Diego; Almeyda Haj-Isa, Niurka M; Morgano, Marcelo Antônio

    2005-12-01

    Food fortification is an interesting strategy to treat and prevent iron anemia. This study aims to quantify the iron in yoghurt, with gelatin and sugar and without, prepared in iron and glass containers. Sensorial test was use to evaluate the acceptance and preference of the both products. The yoghurt was prepared in containers of iron and glass with UHT milk, powder milk and natural industrialized yoghurt. After fermentation, half of the product received addition of sugar and strawberry flavor gelatin. The collected samples get the total iron quantified by ICP OES. Sensorial analysis involving 105 consumers was use to determine the acceptance and preference of the products. 0,018 and 0,882mg of iron per 100g added in the natural yoghurt prepared in the glass and in the iron pots, respectively. The yoghurt with gelatin presented 0,037 and 1,302mg of iron per 100g when prepared in the glass and in the iron pots, respectively. The preference was low for the yoghurt prepared in the iron pot (29,5%), but when added strawberry gelatin it was about 51,5%. The yoghurt prepared in iron pots, is easily home made and adds important amount of iron. Add gelatin and sugar can favored its consumption.

  5. The 'iron salute' in haemochromatosis.

    Science.gov (United States)

    Romas, Evange

    2009-03-01

    The presentation of haemochromatosis is typified by abdominal pain, arthralgia and fatigue or weakness. Arthropathy may be the major presenting feature. The detection of an osteoarthritis-like process involving the metacarpophalangeal (MCP) and wrist joints in middle aged men should signal the possibility of under lying haemochromatosis. Other joints such as the shoulder, hip,knee or ankle may be affected. However, the preferential involvement of the second and third MCP joints is striking and may provide the opportunity for early identification of iron overload disease. The "iron salut" can be an efficient screening tool for this MCP joint arthropathy but it is not well known by clinicians.

  6. Complexed iron removal from groundwater

    Energy Technology Data Exchange (ETDEWEB)

    Munter, R.; Ojaste, H.; Sutt, J. [Tallinn Technical University, Tallinn (Estonia). Dept. of Environmental & Chemical Technology

    2005-07-01

    The paper demonstrates an intensive work carried out and results obtained on the pilot plant of the City of Kogalym Water Treatment Station (Tjumen, Siberia, Russian Federation) to elaborate on a contemporary nonreagent treatment technology for the local iron-rich groundwater. Several filter materials (Birm, Pyrolox, hydroanthracite, Everzit, granulated activated carbon) and chemical oxidants (ozone, chlorine, hydrogen peroxide, oxygen, and potassium permanganate) were tested to solve the problem with complexed iron removal from groundwater. The final elaborated technology consists of raw water intensive aeration in the gas-degas treatment unit followed by sequential filtration through hydroanthracite and the special anthracite Everzit.

  7. Characterization of iron in airborne particulate matter

    Science.gov (United States)

    Tavares, F. V. F.; Ardisson, J. D.; Rodrigues, P. C. H.; Brito, W.; Macedo, W. A. A.; Jacomino, V. M. F.

    2014-01-01

    In this work soil samples, iron ore and airborne atmospheric particulate matter (PM) in the Metropolitan Region of Belo Horizonte (MRBH), State of Minas Gerais, Brazil, are investigated with the aim of identifying if the sources of the particulate matter are of natural origin, such as, resuspension of particles from soil, or due to anthropogenic origins from mining and processing of iron ore. Samples were characterized by powder X-ray diffraction, X-ray fluorescence and 57Fe-Mössbauer spectroscopy. The results showed that soil samples studied are rich in quartz and have low contents of iron mainly iron oxide with low crystallinity. The samples of iron ore and PM have high concentration of iron, predominantly well crystallized hematite. 57Fe-Mössbauer spectroscopy confirmed the presence of similar iron oxides in samples of PM and in the samples of iron ore, indicating the anthropogenic origin in the material present in atmosphere of the study area.

  8. Thermodynamics and Charging of Interstellar Iron Nanoparticles

    CERN Document Server

    Hensley, Brandon S

    2016-01-01

    Interstellar iron in the form of metallic iron nanoparticles may constitute a component of the interstellar dust. We compute the stability of iron nanoparticles to sublimation in the interstellar radiation field, finding that iron clusters can persist down to a radius of $\\simeq 4.5\\,$\\AA, and perhaps smaller. We employ laboratory data on small iron clusters to compute the photoelectric yields as a function of grain size and the resulting grain charge distribution in various interstellar environments, finding that iron nanoparticles can acquire negative charges particularly in regions with high gas temperatures and ionization fractions. If $\\gtrsim 10\\%$ of the interstellar iron is in the form of ultrasmall iron clusters, the photoelectric heating rate from dust may be increased by up to tens of percent relative to dust models with only carbonaceous and silicate grains.

  9. Iron status and the female athlete.

    Science.gov (United States)

    McClung, James P

    2012-06-01

    Iron deficiency (ID) is the most prevalent micronutrient deficiency disorder in the world. In the developed world, the greatest prevalence of ID and iron deficiency anemia (IDA) occurs in premenopausal women. Premenopausal women experience ID and IDA due to inadequate consumption of dietary iron coupled with iron losses through physiologic processes such as menstruation. Further, female athletes may experience an elevated risk of ID and IDA, as hepcidin, a peptide hormone that inhibits iron absorption and sequesters iron in the macrophage, may rise in response to physical activity. Declines in physical and cognitive performance have been demonstrated in female athletes with ID and IDA. Performance decrements are attenuated as iron status improves. This review will focus on iron status in female athletes, and will include a review of nutritional countermeasures to prevent ID and IDA.

  10. Too Much Iron Linked to Gestational Diabetes

    Science.gov (United States)

    ... fullstory_161946.html Too Much Iron Linked to Gestational Diabetes Supplements should only be given to pregnant women ... an increased risk of developing diabetes during pregnancy (gestational diabetes), begging the question whether routine recommendations of iron ...

  11. Thermodynamics and Charging of Interstellar Iron Nanoparticles

    Science.gov (United States)

    Hensley, Brandon S.; Draine, B. T.

    2017-01-01

    Interstellar iron in the form of metallic iron nanoparticles may constitute a component of the interstellar dust. We compute the stability of iron nanoparticles to sublimation in the interstellar radiation field, finding that iron clusters can persist down to a radius of ≃4.5 Å, and perhaps smaller. We employ laboratory data on small iron clusters to compute the photoelectric yields as a function of grain size and the resulting grain charge distribution in various interstellar environments, finding that iron nanoparticles can acquire negative charges, particularly in regions with high gas temperatures and ionization fractions. If ≳10% of the interstellar iron is in the form of ultrasmall iron clusters, the photoelectric heating rate from dust may be increased by up to tens of percent relative to dust models with only carbonaceous and silicate grains.

  12. Iron: a pathological mediator of Alzheimer disease?

    Science.gov (United States)

    Bishop, Glenda M; Robinson, Stephen R; Liu, Quan; Perry, George; Atwood, Craig S; Smith, Mark A

    2002-01-01

    Brains from patients with Alzheimer disease (AD) show a disruption in the metabolism of iron, such that there is an accumulation of iron in senile plaques, and an altered distribution of iron transport and storage proteins. One of the earliest events in AD is the generation of oxidative stress, which may be related to the generation of free radicals by the excess iron that is observed in the disease. Iron has also been shown to mediate the in vitro toxicity of amyloid-beta peptide, and the presence of iron in most in vitro systems could underlie the toxicity that is normally attributed to amyloid-beta in these studies. In contrast, several recent studies have suggested that amyloid-beta may decrease oxidative stress and decrease the toxicity of iron. Continued examination of the complex interactions that occur between iron and amyloid-beta may assist in the elucidation of the mechanisms that underlie the neurodegeneration that leads to dementia in AD.

  13. Fatal overdose of iron tablets in adults.

    Science.gov (United States)

    Abhilash, Kundavaram P P; Arul, J Jonathan; Bala, Divya

    2013-09-01

    Acute iron toxicity is usually seen in children with accidental ingestion of iron-containing syrups. However, the literature on acute iron toxicity with suicidal intent in adults is scant. We report, the first instance of two adults with fatal ingestion of a single drug overdose with iron tablets from India. Two young adults developed severe gastro-intestinal bleeding and fulminant hepatic failure 48 h after deliberate consumption of large doses of iron tablets. Serum iron levels measured 36 h after ingestion were normal presumably due to the redistribution of iron to the intracellular compartment. Despite aggressive supportive management in medical intensive care unit of a tertiary care hospital, the patients succumbed to the toxic doses of iron.

  14. Iron, hepcidin and the metal connection.

    Directory of Open Access Journals (Sweden)

    Olivier eLoréal

    2014-06-01

    Full Text Available Identification of new players in iron metabolism, such as hepcidin, which regulates ferroportin and divalent metal transporter 1 expression, has improved our knowledge of iron metabolism and iron-related diseases. However, from both experimental data and clinical findings, iron-related proteins appear to also be involved in the metabolism of other metals, especially divalent cations. Reports have demonstrated that some metals may affect, directly or indirectly, the expression of proteins involved in iron metabolism. Throughout their lives, individuals are exposed to various metals during personal and/or occupational activities. Therefore, better knowledge of the connections between iron and other metals could improve our understanding of iron-related diseases, especially the variability in phenotypic expression, as well as a variety of diseases in which iron metabolism is secondarily affected. Controlling the metabolism of other metals could represent a promising innovative therapeutic approach.

  15. Development of a clothing iron safety device.

    Science.gov (United States)

    Beers, Ryan; Anthamatten, Mitchell; Reid, Dixie; Kahn, Steven A; Lentz, Christopher W

    2009-01-01

    Contact burns from clothing irons are a common injury seen in children. These injuries occur when an unattended iron is within reach of toddlers in its upright position. In a previous study, the authors have shown that the surface of an iron takes 90 minutes to cool below the epidermal injury threshold of 49 degrees C. The authors have constructed an "iron shoe" to shield the iron surface from young hands during cooling. The device is intended to set the cooling iron in its down position providing additional protection. The device will insulate the iron surface to avoid the fire hazard when positioned in this manner. A silicone polymer was used to create an "iron shoe." This polymer is stable at temperatures up to 370 degrees C. The device included sidewalls to shield the edges from contact. Thermal analysis of the device was conducted using an inexpensive and expensive iron. Thermocouples were placed on the iron surface and below the iron shoe. The irons were heated to its maximum temperature, placed in the shoe and then unplugged. Temperature cooling curves were obtained from the thermocouples. The experiment was repeated by measuring the temperature difference between the iron edge and the shoe sidewalls. The surface of both expensive and inexpensive irons reached a maximum of 205 degrees C. The temperature below the iron shoe reached a maximum of 49 degrees C (inexpensive) and 60 degrees C (expensive). The iron edge temperature reached a maximum of 188 degrees C (inexpensive) and 154 degrees C (expensive). The shoe sidewall temperature achieved a maximum of 52 degrees C (inexpensive) and 49 degrees C (expensive). Both expensive and inexpensive irons reach temperatures over 200 degrees C. The silicone "iron shoe" effectively shielded the surface and edge of both irons and approached the epidermal injury threshold of 49 degrees C. The temperature beneath the expensive iron did exceed 49 degrees C, but because the intention of the device is to place the iron in

  16. The Iron-Iron Carbide Phase Diagram: A Practical Guide to Some Descriptive Solid State Chemistry.

    Science.gov (United States)

    Long, Gary J.; Leighly, H. P., Jr.

    1982-01-01

    Discusses the solid state chemistry of iron and steel in terms of the iron-iron carbide phase diagram. Suggests that this is an excellent way of introducing the phase diagram (equilibrium diagram) to undergraduate students while at the same time introducing the descriptive solid state chemistry of iron and steel. (Author/JN)

  17. An aqueous non-heme Fe(iv)oxo complex with a basic group in the second coordination sphere

    DEFF Research Database (Denmark)

    Vad, Mads Sørensen; Lennartson, Anders; Nielsen, Anne;

    2012-01-01

    The Fe(iv)oxo complex of a coordinatively flexible multidentate mono-carboxylato ligand is obtained by the one electron oxidation of a low spin Fe(iii) precursor in water.......The Fe(iv)oxo complex of a coordinatively flexible multidentate mono-carboxylato ligand is obtained by the one electron oxidation of a low spin Fe(iii) precursor in water....

  18. Triazacyclophane (TAC)-scaffolded histidine and aspartic acid residues as mimics of non-heme metalloenzyme active sites

    NARCIS (Netherlands)

    Albada, H.B.; Soulimani, F.; Jacobs, H.J.F.; Versluis, C.; Weckhuysen, B.M.; Liskamp, R.M.J.

    2012-01-01

    We describe the synthesis and coordination behaviour to copper(II) of two close structural triazacyclophane-based mimics of two often encountered aspartic acid and histidine containing metalloenzyme active sites. Coordination of these mimics to copper(I) and their reaction with molecular oxygen lead

  19. Development of Sintered Iron Driving Bands

    Directory of Open Access Journals (Sweden)

    R. P. Khanna

    1974-07-01

    Full Text Available The present investigation reports some detailed studies carried out on the development testing and proving of sintered Iron Driving Bands. Sintering studies on two different types of iron powders together with a few Fe-Cu compositions have been made and based on the results there of, parameters for development iron driving bands have been standardised. The results obtained clearly demonstrate that substitution of copper by sintered iron is highly practicable alternative.

  20. Iron supplementation and the female soldier.

    Science.gov (United States)

    Johnson, Anthony E

    2006-04-01

    Twenty-two percent of women in the United States are iron deficient. Iron deficiency adversely affects immune function as well as physical and cognitive performance. Although the risk of developing iron deficiency is high for female soldiers, this risk can be minimized with proper nutritional guidance. Recommended dietary modifications include (1) heme iron consumption, (2) ingestion of vitamin C and protein with meals, and (3) discontinued tea and coffee consumption with meals.

  1. The role of ceruloplasmin in iron metabolism.

    Science.gov (United States)

    Roeser, H P; Lee, G R; Nacht, S; Cartwright, G E

    1970-12-01

    The importance of ceruloplasmin in iron metabolism was studied in swine made hypoceruloplasminemic by copper deprivation. When the plasma ceruloplasmin level fell below 1% of normal, cell-to-plasma iron flow became sufficiently impaired to cause hypoferremia, even though total body iron stores were normal. When ceruloplasmin was administered to such animals, plasma iron increased immediately and continued to rise at a rate proportional to the logarithm of the ceruloplasmin dose. The administration of inorganic copper induced increases in plasma iron only after ceruloplasmin appeared in the circulation. Thus, ceruloplasmin appeared to be essential to the normal movement of iron from cells to plasma. Studies designed to define the mechanism of action of ceruloplasmin were based on the in vitro observation that ceruloplasmin behaves as an enzyme (ferroxidase) that catalyzes oxidation of ferrous iron. Retention of injected ferrous iron in the plasma of ceruloplasmin-deficient swine was significantly less than that of ferric iron, reflecting impaired transferrin iron binding. Rat ceruloplasmin, which has little ferroxidase activity, was much less effective than porcine or human ceruloplasmin in inducing increases in plasma iron. These observations suggest that ceruloplasmin acts by virtue of its ferroxidase activity. Eight patients with Wilson's disease were evaluated in order to investigate iron metabolism in a disorder characterized by reduced ceruloplasmin levels. Evidence of iron deficiency was found in six of these, and in five of the six, plasma ceruloplasmin was less than 5% of normal. In comparison, the two patients without evidence of iron deficiency had ceruloplasmin levels of 11 and 18% of normal. It is suggested that iron deficiency tends to occur in those patients with Wilson's disease who have the severest degrees of hypoceruloplasminemia, possibly because of defective transfer of iron from intestinal mucosal cells to plasma.

  2. An unprecedented binuclear cadmium dithiocarbamate adduct: bis[μ2-N-(2-hydroxyethyl-N-isopropylcarbamodithioato-κ3S:S,S′]bis{[N-(2-hydroxyethyl-N-isopropylcarbamodithioato-κ2S,S′](3-{(1E-[(E-2-(pyridin-3-ylmethylidenehydrazin-1-ylidene]methyl}pyridine-κNcadmium]} dihydrate

    Directory of Open Access Journals (Sweden)

    Hadi D. Arman

    2016-09-01

    Full Text Available The asymmetric unit in the title binuclear compound, [Cd(C6H12NOS22(C12H10N4]2·2H2O, comprises a CdII atom, two dithiocarbamate (dtc anions, a monodentate 3-pyridinealdazine ligand and a lattice water molecule. The binuclear molecule is constructed by the application of inversion symmetry. One dtc ligand simultaneously chelates one cadmium atom and bridges the centrosymmetric mate, while the other dtc ligand is chelating only. This leads to a centrosymmetric [Cd(dtc2]2 core to which are appended two 3-pyridinealdazine ligands. The resulting NS5 donor set is based on an octahedron. The three-dimensional molecular packing is sustained by hydroxyl-O—H(hydroxyl and water-O—H...O(hydroxyl hydrogen bonding, leading to supramolecular layers parallel to (101 which are connected by water-O—H...N(pyridyl hydrogen bonding; additional C—H...O, S π(chelate ring interactions are also evident. The retention of the central [Cd(dtc2]2 core upon adduct formation is unprecedented in the structural chemistry of the zinc-triad dithiocarbamates.

  3. Iron requirements of infants and toddlers

    DEFF Research Database (Denmark)

    Domellöf, Magnus; Braegger, Christian; Campoy, Cristina

    2014-01-01

    Iron deficiency (ID) is the most common micronutrient deficiency worldwide and young children are a special risk group since their rapid growth leads to high iron requirements. Risk factors associated with a higher prevalence of iron deficiency anemia (IDA) include low birth weight, high cow's milk...

  4. [Iron and performance in elite athletes].

    Science.gov (United States)

    Romagnoli, Elisa; Cristani, Alessandro

    2006-09-01

    The negative relationship between performance and iron deficiency anemia is well known. There is still debate in the literature on the exercise-induced iron loss and if low iron store, even in the absence of frank anemia, can adversely affected performance of elite athletes. We analyse the physiologic changes induced by strong exercise, the diagnostic problems and therapeutic supplementation.

  5. The Luster of Iron Ore Prices

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    China battles its way out of an iron ore stalemate by finding alternative supplier After months of seesawing, China’s iron ore negotiators appear to be breaking through the tight encirclement of suppliers. On August 17, the China Iron and Steel Association (CISA) announced that Fortescue

  6. Iron mobilization using chelation and phlebotomy

    DEFF Research Database (Denmark)

    Flaten, T. P.; Aaseth, J.; Andersen, Ole;

    2012-01-01

    Knowledge of the basic mechanisms involved in iron metabolism has increased greatly in recent years, improving our ability to deal with the huge global public health problems of iron deficiency and overload. Several million people worldwide suffer iron overload with serious clinical implications....

  7. Iron bioaccumulation in mycelium of Pleurotus ostreatus.

    Science.gov (United States)

    Almeida, Sandra M; Umeo, Suzana H; Marcante, Rafael C; Yokota, Meire E; Valle, Juliana S; Dragunski, Douglas C; Colauto, Nelson B; Linde, Giani A

    2015-03-01

    Pleurotus ostreatus is able to bioaccumulate several metals in its cell structures; however, there are no reports on its capacity to bioaccumulate iron. The objective of this study was to evaluate cultivation variables to increase iron bioaccumulation in P. ostreatus mycelium. A full factorial design and a central composite design were utilized to evaluate the effect of the following variables: nitrogen and carbon sources, pH and iron concentration in the solid culture medium to produce iron bioaccumulated in mycelial biomass. The maximum production of P. ostreatus mycelial biomass was obtained with yeast extract at 2.96 g of nitrogen L (-1) and glucose at 28.45 g L (-1) . The most important variable to bioaccumulation was the iron concentration in the cultivation medium. Iron concentration at 175 mg L (-1) or higher in the culture medium strongly inhibits the mycelial growth. The highest iron concentration in the mycelium was 3500 mg kg (-1) produced with iron addition of 300 mg L (-1) . The highest iron bioaccumulation in the mycelium was obtained in culture medium with 150 mg L (-1) of iron. Iron bioaccumulation in P. ostreatus mycelium is a potential alternative to produce non-animal food sources of iron.

  8. Genetics Home Reference: African iron overload

    Science.gov (United States)

    ... instructions for making a protein called ferroportin. This protein is involved in the process of iron absorption in the body. Iron from the diet is absorbed through the walls of the small intestine. Ferroportin then transports iron from the small intestine ...

  9. Intravenous iron supplementation in children on hemodialysis.

    NARCIS (Netherlands)

    Leijn, E.; Monnens, L.A.H.; Cornelissen, E.A.M.

    2004-01-01

    BACKGROUND: Children with end-stage renal disease (ESRD) on hemodialysis (HD) are often absolute or functional iron deficient. There is little experience in treating these children with intravenous (i.v.) iron-sucrose. In this prospective study, different i.v. iron-sucrose doses were tested in child

  10. Iron Deficiency in Autism and Asperger Syndrome.

    Science.gov (United States)

    Latif, A.; Heinz, P.; Cook, R.

    2002-01-01

    Retrospective analysis of the full blood count and, when available, serum ferritin measurements of 96 children (52 with autism and 44 with Asperger syndrome) found six autistic children had iron deficiency and 12 of the 23 autistic children with serum ferritin measures were iron deficient. Far fewer Asperger children were iron deficient. Results…

  11. Iron bioaccumulation in mycelium of Pleurotus ostreatus

    Directory of Open Access Journals (Sweden)

    Sandra M. Almeida

    2015-03-01

    Full Text Available Pleurotus ostreatus is able to bioaccumulate several metals in its cell structures; however, there are no reports on its capacity to bioaccumulate iron. The objective of this study was to evaluate cultivation variables to increase iron bioaccumulation in P. ostreatusmycelium. A full factorial design and a central composite design were utilized to evaluate the effect of the following variables: nitrogen and carbon sources, pH and iron concentration in the solid culture medium to produce iron bioaccumulated in mycelial biomass. The maximum production of P. ostreatus mycelial biomass was obtained with yeast extract at 2.96 g of nitrogen L−1 and glucose at 28.45 g L−1. The most important variable to bioaccumulation was the iron concentration in the cultivation medium. Iron concentration at 175 mg L−1 or higher in the culture medium strongly inhibits the mycelial growth. The highest iron concentration in the mycelium was 3500 mg kg−1 produced with iron addition of 300 mg L−1. The highest iron bioaccumulation in the mycelium was obtained in culture medium with 150 mg L−1 of iron. Iron bioaccumulation in P. ostreatus mycelium is a potential alternative to produce non-animal food sources of iron.

  12. Ligand iron catalysts for selective hydrogenation

    Science.gov (United States)

    Casey, Charles P.; Guan, Hairong

    2010-11-16

    Disclosed are iron ligand catalysts for selective hydrogenation of aldehydes, ketones and imines. A catalyst such as dicarbonyl iron hydride hydroxycyclopentadiene) complex uses the OH on the five member ring and hydrogen linked to the iron to facilitate hydrogenation reactions, particularly in the presence of hydrogen gas.

  13. Micromilling enhances iron bioaccessibility from wholegrain wheat.

    Science.gov (United States)

    Latunde-Dada, G O; Li, X; Parodi, A; Edwards, C H; Ellis, P R; Sharp, P A

    2014-11-19

    Cereals constitute important sources of iron in human diet; however, much of the iron in wheat is lost during processing for the production of white flour. This study employed novel food processing techniques to increase the bioaccessibility of naturally occurring iron in wheat. Iron was localized in wheat by Perl's Prussian blue staining. Soluble iron from digested wheat flour was measured by a ferrozine spectrophotometric assay. Iron bioaccessibility was determined using an in vitro simulated peptic-pancreatic digestion, followed by measurement of ferritin (a surrogate marker for iron absorption) in Caco-2 cells. Light microscopy revealed that iron in wheat was encapsulated in cells of the aleurone layer and remained intact after in vivo digestion and passage through the gastrointestinal tract. The solubility of iron in wholegrain wheat and in purified wheat aleurone increased significantly after enzymatic digestion with Driselase, and following mechanical disruption using micromilling. Furthermore, following in vitro simulated peptic-pancreatic digestion, iron bioaccessibility, measured as ferritin formation in Caco-2 cells, from micromilled aleurone flour was significantly higher (52%) than from whole aleurone flour. Taken together our data show that disruption of aleurone cell walls could increase iron bioaccessibility. Micromilled aleurone could provide an alternative strategy for iron fortification of cereal products.

  14. Mitochondrial Iron-Sulfur Cluster Activity and Cytosolic Iron Regulate Iron Traffic in Saccharomyces cerevisiae*

    Science.gov (United States)

    Wofford, Joshua D.; Lindahl, Paul A.

    2015-01-01

    An ordinary differential equation-based mathematical model was developed to describe trafficking and regulation of iron in growing fermenting budding yeast. Accordingly, environmental iron enters the cytosol and moves into mitochondria and vacuoles. Dilution caused by increasing cell volume is included. Four sites are regulated, including those in which iron is imported into the cytosol, mitochondria, and vacuoles, and the site at which vacuolar FeII is oxidized to FeIII. The objective of this study was to determine whether cytosolic iron (Fecyt) and/or a putative sulfur-based product of iron-sulfur cluster (ISC) activity was/were being sensed in regulation. The model assumes that the matrix of healthy mitochondria is anaerobic, and that in ISC mutants, O2 diffuses into the matrix where it reacts with nonheme high spin FeII ions, oxidizing them to nanoparticles and generating reactive oxygen species. This reactivity causes a further decline in ISC/heme biosynthesis, which ultimately gives rise to the diseased state. The ordinary differential equations that define this model were numerically integrated, and concentrations of each component were plotted versus the concentration of iron in the growth medium and versus the rate of ISC/heme biosynthesis. Model parameters were optimized by fitting simulations to literature data. The model variant that assumed that both Fecyt and ISC biosynthesis activity were sensed in regulation mimicked observed behavior best. Such “dual sensing” probably arises in real cells because regulation involves assembly of an ISC on a cytosolic protein using Fecyt and a sulfur species generated in mitochondria during ISC biosynthesis and exported into the cytosol. PMID:26306041

  15. Effect of intravenous iron supplementation on iron stores in non-anemic iron-deficient patients with hereditary hemorrhagic telangiectasia

    Directory of Open Access Journals (Sweden)

    Torbjörn Karlsson

    2016-03-01

    Full Text Available In hereditary hemorrhagic telangiectasia (HHT, frequent episodes of nasal and gastrointestinal bleeding commonly lead to irondeficiency with or without anemia. In the retrospective study presented here we assessed the iron stores, as determined by analysis of plasma ferritin, during oral and intravenous iron supplementation, respectively, in a population of iron-deficient non-anemic HHT patients who were inadequately iron-repleted by oral supplementation. A switch from oral to intravenous iron supplementation was associated with a significant increase in ferritin in this patient population.

  16. Iron, Anemia, and Iron Deficiency Anemia among Young Children in the United States

    OpenAIRE

    Gupta, Priya M.; Perrine, Cria G.; Zuguo Mei; Scanlon, Kelley S.

    2016-01-01

    Iron deficiency and anemia are associated with impaired neurocognitive development and immune function in young children. Total body iron, calculated from serum ferritin and soluble transferrin receptor concentrations, and hemoglobin allow for monitoring of the iron and anemia status of children in the United States. The purpose of this analysis is to describe the prevalence of iron deficiency (ID), anemia, and iron deficiency anemia (IDA) among children 1–5 years using data from the 2007–201...

  17. Effects of digoxin on cardiac iron content in rat model of iron overload

    OpenAIRE

    Nasri, Hamid Reza; Shahouzehi, Beydolah; Masoumi-Ardakani, Yaser; Iranpour, Maryam

    2016-01-01

    BACKGROUND Plasma iron excess can lead to iron accumulation in heart, kidney and liver. Heart failure is a clinical widespread syndrome. In thalassemia, iron overload cardiomyopathy is caused by iron accumulation in the heart that leads to cardiac damage and heart failure. Digoxin increases the intracellular sodium concentration by inhibition of Na+/K+-ATPase that affects Na+/Ca2+ exchanger (NCX), which raises intracellular calcium and thus attenuates heart failure. The mechanism of iron upta...

  18. Atmospheric iron deposition: global distribution, variability, and human perturbations.

    Science.gov (United States)

    Mahowald, Natalie M; Engelstaedter, Sebastian; Luo, Chao; Sealy, Andrea; Artaxo, Paulo; Benitez-Nelson, Claudia; Bonnet, Sophie; Chen, Ying; Chuang, Patrick Y; Cohen, David D; Dulac, Francois; Herut, Barak; Johansen, Anne M; Kubilay, Nilgun; Losno, Remi; Maenhaut, Willy; Paytan, Adina; Prospero, Joseph M; Shank, Lindsey M; Siefert, Ronald L

    2009-01-01

    Atmospheric inputs of iron to the open ocean are hypothesized to modulate ocean biogeochemistry. This review presents an integration of available observations of atmospheric iron and iron deposition, and also covers bioavailable iron distributions. Methods for estimating temporal variability in ocean deposition over the recent past are reviewed. Desert dust iron is estimated to represent 95% of the global atmospheric iron cycle, and combustion sources of iron are responsible for the remaining 5%. Humans may be significantly perturbing desert dust (up to 50%). The sources of bioavailable iron are less well understood than those of iron, partly because we do not know what speciation of the iron is bioavailable. Bioavailable iron can derive from atmospheric processing of relatively insoluble desert dust iron or from direct emissions of soluble iron from combustion sources. These results imply that humans could be substantially impacting iron and bioavailable iron deposition to ocean regions, but there are large uncertainties in our understanding.

  19. Iron oxides in human spleen.

    Science.gov (United States)

    Kopáni, Martin; Miglierini, Marcel; Lančok, Adriana; Dekan, Július; Čaplovicová, Mária; Jakubovský, Ján; Boča, Roman; Mrazova, Hedviga

    2015-10-01

    Iron is an essential element for fundamental cell functions and a catalyst for chemical reactions. Three samples extracted from the human spleen were investigated by scanning (SEM) and transmission electron microscopy (TEM), Mössbauer spectrometry (MS), and SQUID magnetometry. The sample with diagnosis of hemosiderosis (H) differs from that referring to hereditary spherocytosis and the reference sample. SEM reveals iron-rich micrometer-sized aggregate of various structures-tiny fibrils in hereditary spherocytosis sample and no fibrils in hemochromatosis. Hematite and magnetite particles from 2 to 6 μm in TEM with diffraction in all samples were shown. The SQUID magnetometry shows different amount of diamagnetic, paramagnetic and ferrimagnetic structures in the tissues. The MS results indicate contribution of ferromagnetically split sextets for all investigated samples. Their occurrence indicates that at least part of the sample is magnetically ordered below the critical temperature. The iron accumulation process is different in hereditary spherocytosis and hemosiderosis. This fact may be the reason of different iron crystallization.

  20. Dynamic transition in supercritical iron.

    Science.gov (United States)

    Fomin, Yu D; Ryzhov, V N; Tsiok, E N; Brazhkin, V V; Trachenko, K

    2014-11-26

    Recent advance in understanding the supercritical state posits the existence of a new line above the critical point separating two physically distinct states of matter: rigid liquid and non-rigid gas-like fluid. The location of this line, the Frenkel line, remains unknown for important real systems. Here, we map the Frenkel line on the phase diagram of supercritical iron using molecular dynamics simulations. On the basis of our data, we propose a general recipe to locate the Frenkel line for any system, the recipe that importantly does not involve system-specific detailed calculations and relies on the knowledge of the melting line only. We further discuss the relationship between the Frenkel line and the metal-insulator transition in supercritical liquid metals. Our results enable predicting the state of supercritical iron in several conditions of interest. In particular, we predict that liquid iron in the Jupiter core is in the "rigid liquid" state and is highly conducting. We finally analyse the evolution of iron conductivity in the core of smaller planets such as Earth and Venus as well as exoplanets: as planets cool off, the supercritical core undergoes the transition to the rigid-liquid conducting state at the Frenkel line.

  1. Working with the "Iron Hammer"

    Institute of Scientific and Technical Information of China (English)

    1996-01-01

    CUTTING short her education and abandoning an annual income of several hundred thousand US dollars, Lang Ping, known to fans as the "Iron Hammer", returned from the United States to coach China’s National Women’s Volleyball Team. This news caused an enormous sensation comparable to the stir she used to raise when she won, together with her teammates, championship for

  2. Transformation rate between ferritin and hemosiderin assayed by serum ferritin kinetics in patients with normal iron stores and iron overload.

    Science.gov (United States)

    Saito, Hiroshi; Hayashi, Hisao

    2015-11-01

    Ferritin iron, hemosiderin iron, total iron stores and transformation rate were determined by serum ferritin kinetics. The transformation rate between ferritin and hemosiderin is motivated by the potential difference between them. The transformer determines transformation rate according to the potential difference in iron mobilization and deposition. The correlations between transformation rate and iron stores were studied in 11 patients with chronic hepatitis C (CHC), 1 patent with treated iron deficiency anemia (TIDA), 9 patients with hereditary hemochromatosis (HH) and 4 patients with transfusion-dependent anemia (TD). The power regression curve of approximation showed an inverse correlation between transformation rate and ferritin iron, hemosiderin iron in part and total iron stores in HH. Such an inverse correlation between transformation rate and iron stores implies that the larger the amount of iron stores, the smaller the transformation of iron stores. On the other hand, a minimal inverse correlation between transformation rate and ferritin iron and no correlation between transformation rate and hemosiderin iron or total iron stores in CHC indicate the derangement of storage iron metabolism in the cells with CHC. Radio-iron fixation on the iron storing tissue in iron overload was larger than that in normal subjects by ferrokinetics. This is consistent with the inverse correlation between transformation rate and total iron stores in HH. The characteristics of iron turnover between ferritin and hemosiderin were disclosed from the correlation between transformation rate and ferritin iron, hemosiderin iron or total iron stores.

  3. Efficacy of iron-fortified whole maize flour on iron status of schoolchildren in Kenya: a randomised controlled trial

    NARCIS (Netherlands)

    Andang'o, P.E.A.; Osendarp, S.J.M.; Ayah, R.; West, C.E.; Mwaniki, D.; Wolf, de C.A.; Kraaijenhagen, R.; Kok, F.J.; Verhoef, H.

    2007-01-01

    Background Sodium iron edetic acid (NaFeEDTA) might be a more bioavailable source of iron than electrolytic iron, when added to maize flour. We aimed to assess the effect, on children's iron status, of consumption of whole maize flour fortified with iron as NaFeEDTA or electrolytic iron. Methods 516

  4. Iron, anemia and hepcidin in malaria

    Directory of Open Access Journals (Sweden)

    Natasha eSpottiswoode

    2014-05-01

    Full Text Available Malaria and iron have a complex but important relationship. Plasmodium proliferation requires iron, both during the clinically silent liver stage of growth and in the disease-associated phase of erythrocyte infection. Precisely how the protozoan acquires its iron from its mammalian host remains unclear, but iron chelators can inhibit pathogen growth in vitro and in animal models. In humans, iron deficiency appears to protect against severe malaria, while iron supplementation increases risks of infection and disease. Malaria itself causes profound disturbances in physiological iron distribution and utilization, through mechanisms that include hemolysis, release of heme, dyserythropoiesis, anemia, deposition of iron in macrophages, and inhibition of dietary iron absorption. These effects have significant consequences. Malarial anemia is a major global health problem, especially in children, that remains incompletely understood and is not straightforward to treat. Furthermore, the changes in iron metabolism during a malaria infection may modulate susceptibility to coinfections. The release of heme and accumulation of iron in granulocytes may explain increased vulnerability to non-typhoidal Salmonella during malaria. The redistribution of iron away from hepatocytes and into macrophages may confer host resistance to superinfection, whereby blood-stage parasitemia prevents the development of a second liver-stage Plasmodium infection in the same organism. Key to understanding the pathophysiology of iron metabolism in malaria is the activity of the iron regulatory hormone hepcidin. Hepcidin is upregulated during blood-stage parasitemia and likely mediates much of the iron redistribution that accompanies disease. Understanding the regulation and role of hepcidin may offer new opportunities to combat malaria and formulate better approaches to treat anemia in the developing world.

  5. Treatment of iron deficiency anemia: are monomeric iron compounds suitable for parenteral administration?

    Science.gov (United States)

    Gupta, A; Crumbliss, A L

    2000-11-01

    Iron deficiency is the most common nutritional problem worldwide, especially in the developing countries. Oral iron supplementation programs have failed because of noncompliance and gastrointestinal toxicity, thereby necessitating parenteral administration of iron. For parenteral administration, only iron-carbohydrate complexes are currently used, because monomeric iron salts release free iron, thereby causing oxidant injury. However, iron-carbohydrate complexes also have significant toxicity, and they are expensive. We have proposed the hypothesis that monomeric iron salts can be safely administered by the parenteral route if iron is tightly complexed to the ligand, thereby causing clinically insignificant release of free iron, and the kinetic properties of the compound allow rapid transfer of iron to plasma transferrin. A detailed analysis of the physicochemical and kinetic properties reveals that ferric iron complexed to pyrophosphate or acetohydroxamate anions may be suitable for parenteral administration. We have demonstrated that infusion of ferric pyrophosphate into the circulation via the dialysate is safe and effective in maintaining iron balance in patients undergoing maintenance hemodialysis. Parenteral administration of monomeric iron compounds is a promising approach to the treatment of iron deficiency in the general population and merits further investigation.

  6. Synthesis and electrochemical and spectroscopic properties of a series of binuclear and trinuclear ruthenium and palladium complexes based on a new bridging ligand containing terpyridyl and catechol binding sites

    Energy Technology Data Exchange (ETDEWEB)

    Whittle, B.; Everest, N.S.; Howard, C.; Ward, M.D. [Univ. of Bristol (United Kingdom)

    1995-04-12

    The ligand 4{prime}-(3,4-dimethoxyphenyl)-2,2{prime}:6{prime},2{double_prime}-terpyridine (L{sup 2}), containing a terpyridyl binding site and a masked catechol binding site, was prepared by a standard Kroehnke-type synthesis. From this the complexes [Ru(terpy)-(L{sup 2})][PF{sub 6}]{sub 2} (1) and [Ru(L{sup 2}){sub 2}][PF{sub 6}]{sub 2} (2), containing one and two dimethoxyphenyl substituents, were prepared: demethylation with BBr{sub 3} afforded [Ru(terpy)(H{sub 2}L{sup 1})][PF{sub 6}]{sub 2} (3) and [Ru(H{sub 2}L{sup 1}){sub 2}][PF{sub 6}]{sub 2} (4), respectively, which have one or two free catechol binding sites pendant from the [Ru(terpy){sub 2}]{sup 2+} core. Binuclear complexes (based on 3) and trinuclear complexes (based on 4) were then prepared by attachment of other metal fragments at the catechol sites. In [Ru(terpy)({mu}-L{sup 1})Ru(bipy){sub 2}][PF{sub 6}]{sub 3} (5) and [Ru({mu}-L{sup 1}){sub 2}(Ru(bipy){sub 2}){sub 2}][PF{sub 6}]{sub 4} (6) the pendant (Ru(bipy){sub 2}(O-O)){sup n+} sites (O-O = catecholate, n = 0; o-benzosemiquinone, n = 1; o-benzoquinone, n = 2) are redox active and may be reversibly interconverted between the three oxidation levels. In [Ru(terpy)({mu}-L{sup 1})Pd(bipy)][PF{sub 6}]{sub 2} (7), [Ru({mu}-L{sup 1}){sub 2}(Pd(bipy)){sub 2}][PF{sub 6}]{sub 2} (8), [Ru(terpy)({mu}-L{sup 1})Pd(4,4{prime}-{sup t}Bu{sub 2}-bipy)][PF{sub 6}]{sub 2} (9), and [Ru({mu}-L{sup 1}){sub 2}(Pd(4,4{prime}-{sup t}Bu{sub 2}-bipy)){sub 2}][PF{sub 6}]{sub 2} (10) the pendant (Pd(bipy)(catecholate)) fragments are known to be photocatalysts for production of {sup 1}O{sub 2} in their own right. Electrochemical and UV/vis studies were performed on all complexes and consistently indicate the presence of interactions between the components in 5-10. The EPR spectrum of 6 (which contains two semiquinone radicals) shows that the two spins are coupled by an exchange interaction.

  7. 席夫碱大环双核锌配合物的合成与表征%Synthesis and crystal structure of macrocyclic Schiff base binuclear zinc( Ⅱ )complex

    Institute of Scientific and Technical Information of China (English)

    康海霞; 马宁; 傅玉琴; 李森兰

    2012-01-01

    A tetraaza macrocyclic Schiff base was synthesized through the reaction of acetone and ethylenediamine by the catalysis of perchloric acid. The Schiff base reacted with ZnO and NaN3 to form a binuclear zinc ( Ⅱ ) macrocyclic complex. The complex was characterized by infrared spectrum and X-Ray single crystal diffraction. It belongs to monoclinic system with space groupC2/c,α = 2.4914(2)nm,b = 1.4 9748(13)nm,c=1.26800(11)nm;β=l02. 1900( 10)°;v=4. 6240(7)nm3 ,Z=4,Dc = 1.482 Mg/m\\Mr = 1032.03 ,F(000)= 2160,final R=0.0506,wR = 0. 1434. The Zinc atom is five-coordinated by five nitrogen atoms(four nitrogen atoms come from the Schiff base and one nitrogen atom comes from the azido anion). As a result, a slightly distorted triangle double-cone geometry forms.%本文用丙酮和乙二胺在高氯酸催化下合成了四氮杂十四环席夫碱(1),并用此化合物(1)与氧化锌和叠氮化钠反应,生成锌的双核大环配合物.通过X-射线单晶衍射和红外光谱对其进行了结构表征.该配合物属单斜晶系,C2/c空间群,晶胞参数为a=2.4914 (2) nm,b=1.4 9748 (13) nm,c=1.26800( 11 )nm;β=102.1900(10)°;v=4.6240(7) nm3,Z=4,Dc=1.482Mg/m3,Mr=1032.03,F(000)=2160,最终R=0.0506,wR=0.1434.该配合物中锌原子是五配位,它们分别和大环配体上的4个氮原子及叠氮根负离子两端的氮原子配位形成畸变的三角双锥构型.

  8. 新型双核阳离子离子液体催化合成庚二酸二乙酯%SYNTHESIS OF DIETHYL PIMELATE BY A NEW IONIC LIQUID WITH BINUCLEAR CATIONS

    Institute of Scientific and Technical Information of China (English)

    赵振贵; 李华; 赵蕾

    2011-01-01

    A new ionic liquid with strong acid binuclear cations, namely, N, N'-alkyl-(3-methyl)-diimidazolium hydrogen sulfate, is used for the esterification of 1,7-pimelic acid and ethanol.The products and ionic liquids can be separated by simple methods.The esterification products could be easily separated in high yield from the reaction system via simple phase separation.The effects of the reaction conditions on the reaction results, such as the amount of catalyst, molar ratio of acid and alcohol, reaction time, etc, were examined and the optimal, conditions were obtained through orthogonally designed experiments based on single-factor experiments.The optimal conditions were found as follows: n(C2H5OH)∶ n(C7H1204)=3∶ 1, 11.1% catalyst , 5.5 h and 108 ℃.Under the optimal reaction conditions, the yield was 97.81%.Separated from the products, the ionic liquids could be reused for 5 times and the yields were up to 96.65%.Compared with the concentrated sulfuric acid, the traditional catalyst, the ionic liquids have the advantages of excellent stability, less pollution, less side reaction, good repeatability, and no organic solvent being required as water carrying agent.%制备一种新型强酸性双核阳离子离子液体N,N'-烷基-(3-甲基)-二咪唑硫酸氢盐,用于1,7-庚二酸和乙醇的酯化反应,通过简单的处理就可以实现产品和离子液体的分离.采用单因素和正交实验考察了催化剂用量、反应时间、反应温度和醇酸比对反应的影响,最佳反应条件为:n(CHOH):n(CHO)=3:1、催化剂用量11.1%、反应时间5.5 h、反应温度108℃,庚二酸二乙酯收率为97.81%.离子液体重复使用 5 次,庚二酸二乙酯的收率均在96.65%以上.

  9. Myelodysplastic Syndromes and Iron Chelation Therapy

    Science.gov (United States)

    Angelucci, Emanuele; Urru, Silvana Anna Maria; Pilo, Federica; Piperno, Alberto

    2017-01-01

    Over recent decades we have been fortunate to witness the advent of new technologies and of an expanded knowledge and application of chelation therapies to the benefit of patients with iron overload. However, extrapolation of learnings from thalassemia to the myelodysplastic syndromes (MDS) has resulted in a fragmented and uncoordinated clinical evidence base. We’re therefore forced to change our understanding of MDS, looking with other eyes to observational studies that inform us about the relationship between iron and tissue damage in these subjects. The available evidence suggests that iron accumulation is prognostically significant in MDS, but levels of accumulation historically associated with organ damage (based on data generated in the thalassemias) are infrequent. Emerging experimental data have provided some insight into this paradox, as our understanding of iron-induced tissue damage has evolved from a process of progressive bulking of organs through high-volumes iron deposition, to one of ‘toxic’ damage inflicted through multiple cellular pathways. Damage from iron may, therefore, occur prior to reaching reference thresholds, and similarly, chelation may be of benefit before overt iron overload is seen. In this review, we revisit the scientific and clinical evidence for iron overload in MDS to better characterize the iron overload phenotype in these patients, which differs from the classical transfusional and non-transfusional iron overload syndrome. We hope this will provide a conceptual framework to better understand the complex associations between anemia, iron and clinical outcomes, to accelerate progress in this area. PMID:28293409

  10. Cancer cells with irons in the fire.

    Science.gov (United States)

    Bystrom, Laura M; Rivella, Stefano

    2015-02-01

    Iron is essential for the growth and proliferation of cells, as well as for many biological processes that are important for the maintenance and survival of the human body. However, excess iron is associated with the development of cancer and other pathological conditions, due in part to the pro-oxidative nature of iron and its damaging effects on DNA. Current studies suggest that iron depletion may be beneficial for patients that have diseases associated with iron overload or other iron metabolism disorders that may increase the risk for cancer. On the other hand, studies suggest that cancer cells are more vulnerable to the effects of iron depletion and oxidative stress in comparison to normal cells. Therefore, cancer patients might benefit from treatments that alter both iron metabolism and oxidative stress. This review highlights the pro-oxidant effects of iron, the relationship between iron and cancer development, the vulnerabilities of the iron-dependent cancer phenotype, and how these characteristics may be exploited to prevent or treat cancer.

  11. Parkinson's Disease: The Mitochondria-Iron Link.

    Science.gov (United States)

    Muñoz, Yorka; Carrasco, Carlos M; Campos, Joaquín D; Aguirre, Pabla; Núñez, Marco T

    2016-01-01

    Mitochondrial dysfunction, iron accumulation, and oxidative damage are conditions often found in damaged brain areas of Parkinson's disease. We propose that a causal link exists between these three events. Mitochondrial dysfunction results not only in increased reactive oxygen species production but also in decreased iron-sulfur cluster synthesis and unorthodox activation of Iron Regulatory Protein 1 (IRP1), a key regulator of cell iron homeostasis. In turn, IRP1 activation results in iron accumulation and hydroxyl radical-mediated damage. These three occurrences-mitochondrial dysfunction, iron accumulation, and oxidative damage-generate a positive feedback loop of increased iron accumulation and oxidative stress. Here, we review the evidence that points to a link between mitochondrial dysfunction and iron accumulation as early events in the development of sporadic and genetic cases of Parkinson's disease. Finally, an attempt is done to contextualize the possible relationship between mitochondria dysfunction and iron dyshomeostasis. Based on published evidence, we propose that iron chelation-by decreasing iron-associated oxidative damage and by inducing cell survival and cell-rescue pathways-is a viable therapy for retarding this cycle.

  12. Milk versus medicine for the treatment of iron deficiency anaemia in hospitalised infants

    OpenAIRE

    Wall, C.; Grant, C.; Taua, N; Wilson, C.; Thompson, J.

    2005-01-01

    Aims: To compare iron fortified follow-on milk (iron follow-on), iron fortified partially modified cows' milk (iron milk), and iron medicine for the treatment of iron deficiency anaemia (IDA) in hospitalised infants.

  13. Radiation stability of iron nanoparticles irradiated with accelerated iron ions

    Energy Technology Data Exchange (ETDEWEB)

    Uglov, V.V., E-mail: uglov@bsu.by [Belarusian State University, Nezavisimosty ave., 4, Minsk 220030 (Belarus); Tomsk Polytechnic University, Lenina ave., 2a, Tomsk 634028 (Russian Federation); Remnev, G.E., E-mail: remnev06@mail.ru [Tomsk Polytechnic University, Lenina ave., 2a, Tomsk 634028 (Russian Federation); Kvasov, N.T.; Safronov, I.V.; Shymanski, V.I. [Belarusian State University, Nezavisimosty ave., 4, Minsk 220030 (Belarus)

    2015-07-01

    Highlights: • Dynamic processes in nanoparticles after ion irradiation were studied. • The mechanism of the enhanced radiation stability of nanoparticles was showed. • The criteria of the enhanced radiation stability of nanoparticles was proposed. - Abstract: In the present work the dynamic processes occurring in a nanoscale iron particle exposed to irradiation with iron ions of different energies are studied in detailed. It is shown that the elastic and thermoelastic crystal lattice responses to irradiation form force factors affecting the evolution of defect-impurity system, which, in turn, leads to a decrease in the number of structural defects. Quantitative estimations of the spatial distribution of defects resulting in their migration to the surface were obtained. Such self-organization of nanoparticles exposed to ionizing radiation can be used as a basis for the production of radiation-resistant nanostructured materials capable of sustaining a long-term radiation influence.

  14. Iron in haemoglobinopathies and rare anaemias

    Directory of Open Access Journals (Sweden)

    John Porter

    2014-12-01

    Full Text Available Iron overload in haemoglobinopathies and rare anaemias may develop from increased iron absorption secondary to hepcidin suppression, and/or from repeated blood transfusions. While the accumulation of body iron load from blood transfusion is inevitable and predictable from the variable rates of transfusion in the different conditions, there are some important differences in the distribution of iron overload and its consequences between these. Transfusion-dependent thalassaemia (TDT is the best described condition in which transfusional overload occurs. Initially iron loads into macrophages, subsquently hepatocytes, and then the endocrine system including the anterior pituiatry and finally the myocardium. The propensity to extrahepatic iron spread increases with rapid transfusion and with inadequate chelation therapy but there is considerable interpatient and interpopulation variability in this tendency. The conduits though which iron is delivered to tissues is through non transferrin iron species (NTBI which are taken into liver, endocrine tissues and myocardium through L-type calcium channells and possibly through other channells. Recent work by the MSCIO group1 suggests that levels of NTBI are determined by three mechanisms: i increasing with iron overload; ii increasing with ineffective erythropoieis; iii and decreasing when level of transferrin iron utilisation is high. In TDT all three mechanisms increase NTBI levels because transferrin iron utilisation is suppressed by hypertransfusion. It is hypothesized that the transfusion regimen and target mean Hb may have a key impact on NTBI levels because high transfusion regimes may suppress the ‘sink’ effect of the erythron though decreased clearance of transferrin iron. In sickle cell disease (SCD without blood transfusion the anaemia results mainly from haemolysis rather than from ineffective erythropoiesis.2 Thus there is a tendency to iron depletion because of urinary iron loss from

  15. Iron supplementation for female athletes: effects on iron status and performance outcomes.

    Science.gov (United States)

    DellaValle, Diane M

    2013-01-01

    Iron is an essential micronutrient involved in oxidative metabolism and critical to exercise performance. The prevalence of iron deficiency (ID) is much higher in active women for a variety of reasons, and poor iron status has been shown to be detrimental to overall health as well as physical performance. Iron status can be assessed using a number of indicators; however clinical cut-offs for active populations remain controversial. Randomized, placebo-controlled supplementation trials of iron-depleted female athletes have shown that oral iron supplementation in doses of 100-mg FeSO4·d (approximately 20 mg elemental iron) improves iron status and may improve measures of physical performance. It is recommended that female athletes most at risk of ID be screened at the beginning of and during the training season using hemoglobin and serum ferritin, and appropriate dietary and/or supplementation recommendations be made to those with compromised iron status.

  16. Iron regulatory proteins control a mucosal block to intestinal iron absorption.

    Science.gov (United States)

    Galy, Bruno; Ferring-Appel, Dunja; Becker, Christiane; Gretz, Norbert; Gröne, Hermann-Josef; Schümann, Klaus; Hentze, Matthias W

    2013-03-28

    Mammalian iron metabolism is regulated systemically by the hormone hepcidin and cellularly by iron regulatory proteins (IRPs) that orchestrate a posttranscriptional regulatory network. Through ligand-inducible genetic ablation of both IRPs in the gut epithelium of adult mice, we demonstrate that IRP deficiency impairs iron absorption and promotes mucosal iron retention via a ferritin-mediated "mucosal block." We show that IRP deficiency does not interfere with intestinal sensing of body iron loading and erythropoietic iron need, but rather alters the basal expression of the iron-absorption machinery. IRPs thus secure sufficient iron transport across absorptive enterocytes by restricting the ferritin "mucosal block" and define a basal set point for iron absorption upon which IRP-independent systemic regulatory inputs are overlaid.

  17. Iron Regulatory Proteins Control a Mucosal Block to Intestinal Iron Absorption

    Directory of Open Access Journals (Sweden)

    Bruno Galy

    2013-03-01

    Full Text Available Mammalian iron metabolism is regulated systemically by the hormone hepcidin and cellularly by iron regulatory proteins (IRPs that orchestrate a posttranscriptional regulatory network. Through ligand-inducible genetic ablation of both IRPs in the gut epithelium of adult mice, we demonstrate that IRP deficiency impairs iron absorption and promotes mucosal iron retention via a ferritin-mediated “mucosal block.” We show that IRP deficiency does not interfere with intestinal sensing of body iron loading and erythropoietic iron need, but rather alters the basal expression of the iron-absorption machinery. IRPs thus secure sufficient iron transport across absorptive enterocytes by restricting the ferritin “mucosal block” and define a basal set point for iron absorption upon which IRP-independent systemic regulatory inputs are overlaid.

  18. Effects of heme iron enriched peptide on iron deficiency anemia in rats.

    Science.gov (United States)

    Tang, Ning; Chen, Le-qun; Zhuang, Hong

    2014-02-01

    The present study aims to investigate whether a daily intake of heme iron enriched peptide obtained from bovine hemoglobin is effective in alleviating iron deficiency anemia (IDA). Wistar rats were randomly divided into six groups: a control group, an anemic group not treated, and anemic groups treated with FeSO4 or with the heme iron enriched peptide at low, moderate or high doses. The rats in the anemic groups were fed on a low-iron diet to establish the iron deficiency anemia model. After the model had been established, different doses of heme iron enriched peptide were given to the rats once a day via intragastric administration. After the iron supplement administration, it was observed that heme iron enriched peptide had effective restorative action returning the hemoglobin, red blood cells, hematocrit, mean corpuscular volume, mean corpuscular hemoglobin concentration and serum iron in IDA animals to normal values or better. In addition, compared with FeSO4, higher Fe bioavailability and fewer side effects were observed. The rats in the moderate dose group had the highest apparent Fe absorption. Moreover, in vivo antioxidant activity was also observed, enhancing the activities of antioxidant enzymes and reduced malondialdehyde levels in IDA rats. Furthermore, the heme iron enriched peptide also exhibited strong in vitro antioxidant activities. In conclusion, heme iron enriched peptide significantly alleviated iron deficiency anemia, and exhibited strong in vitro and in vivo antioxidant activities. This suggests that heme iron enriched peptide might be exploited as a safe, efficient new iron supplement.

  19. Reductive denitrification using zero-valent iron and bimetallic iron.

    Science.gov (United States)

    Choi, Jeong-Hak; Shinb, Won Sik; Choi, Sang June; Kim, Young-Hun

    2009-08-01

    A study of reductive denitrification of nitrate was conducted. Microscale zero-valent iron (ZVI) and palladium-coated iron (Pd/Fe) were used in the reduction of nitrate with variable pH. The solution pH was controlled by an auto controlling system instead of chemical buffers. Higher reduction rates were achieved with lower pH and lower pH gave the pseudo-first-order kinetics while it was close to the zero-order reaction when the pH of the solution was becoming high and nitrate concentration was higher. As it took several hours to convert intermediates to ammonia completely, the assumption, under which mass loss calculated from the measured ammonia concentration right after the reaction was the mass of nitrogen evolved, could lead to overestimation of the nitrogen selectivity. The current study confirmed that the palladium coating on the iron could increase the nitrogen selectivity, and the Pd/Fe system could also achieve the advantages of coupling of electron source and catalyst with regard to the engineering aspects.

  20. Inevitable iron loss by human adolescents, with calculations of the requirement for absorbed iron.

    Science.gov (United States)

    Fomon, Samuel J; Drulis, Jean M; Nelson, Steven E; Serfass, Robert E; Woodhead, Jerold C; Ziegler, Ekhard E

    2003-01-01

    In growing individuals, the requirement for absorbed iron consists of iron needed for growth and iron needed to replace inevitable iron loss. We were able to estimate inevitable iron loss by adolescents because total body iron of the adolescents had been enriched with the stable isotope, (58)Fe, as the result of earlier studies of iron absorption. During an interval beginning at least 1.56 y after isotope administration (a time sufficient for complete mixing of the isotope with total body iron) and extending for no less than 3.29 y, we determined the isotopic enrichment of circulating iron. On the basis of several assumptions, we calculated total body (58)Fe and total body iron at the beginning and end of the interval. Because of complete mixing of the isotope with total body iron, fractional total (58)Fe loss was the same as fractional loss of total iron. In males, the fractional loss of iron was 9.70%/y and the quantitative loss was 256 mg/y or 0.70 mg/d. In females, the fractional loss of iron was 14.60%/y and the quantitative loss was 306 mg/y or 0.84 mg/d. Using several assumptions, we then calculated that the iron requirement for growth during this interval was 0.76 mg/d for males and 0.31 mg/d for females. Adding the iron loss to the iron requirement for growth, the requirement for absorbed iron was estimated to be 1.46 mg/d for males and 1.15 mg/d for females.

  1. Iron deficiency in sports - definition, influence on performance and therapy

    OpenAIRE

    Clénin, German; Cordes, Mareike; Huber, Andreas; Schumacher, Yorck Olaf; Noack, Patrick; Scales, John; Kriemler, Susi

    2015-01-01

    Iron deficiency is frequent among athletes. All types of iron deficiency may affect physical performance and should be treated. The main mechanisms by which sport leads to iron deficiency are increased iron demand, elevated iron loss and blockage of iron absorption due to hepcidin bursts. As a baseline set of blood tests, haemoglobin, haematocrit, mean cellular volume, mean cellular haemoglobin and serum ferritin levels help monitor iron deficiency. In healthy male and female athletes >15 yea...

  2. Atmospheric iron deposition: global distribution, variability, and human perturbations

    OpenAIRE

    N. Mahowald; S. Engelstaedter; Luo, C; Sealy, A.; Artaxo, P.; Benitez-Nelson, C.R.; Bonnet, S.; Chen, Y.; Chuang, P. Y.; Cohen, D.; Dulac, F.; B. Herut; Johansen, A.M.; N. Kubilay; Losno, R.

    2009-01-01

    Atmospheric inputs of iron to the open ocean are hypothesized to modulate ocean biogeochemistry. This review presents an integration of available observations of atmospheric iron and iron deposition, and also covers bioavailable iron distributions. Methods for estimating temporal variability in ocean deposition over the recent past are reviewed. Desert dust iron is estimated to represent 95% of the global atmospheric iron cycle, and combustion sources of iron are responsible for the remaining...

  3. Adiposity in women and children from transition countries predicts decreased iron absorption, iron deficiency and a reduced response to iron fortification

    NARCIS (Netherlands)

    Zimmermann, M.B.; Zeder, C.; Muthayya, S.; Winichagoon, P.; Chaouki, N.; Aeberli, I.; Hurrell, R.F.

    2008-01-01

    Background: Overweight is increasing in transition countries, while iron deficiency remains common. In industrialized countries, greater adiposity increases risk of iron deficiency. Higher hepcidin levels in obesity may reduce dietary iron absorption. Therefore, we investigated the association betwe

  4. Nitrate-dependent iron oxidation limits iron transport in anoxic ocean regions

    DEFF Research Database (Denmark)

    Scholz, Florian; Löscher, Carolin; Fiskal, Annika;

    2016-01-01

    campaign the water column featured two distinct redox boundaries separating oxic from nitrate-reducing (i.e., nitrogenous) water and nitrogenous from weakly sulfidic water. The sulfidic water mass in contact with the shelf sediment contained elevated iron concentrations>300 nM. At the boundary between...... sulfidic and nitrogenous conditions, iron concentrations dropped sharply to ... to the activity of known iron-oxidizing bacteria. Collectively, our data suggest that iron oxidation and removal is induced by nitrate-reducing microbes, either enzymatically through anaerobic iron oxidation or by providing nitrite for an abiotic reaction. Given the important role that iron plays in nitrogen...

  5. Iron-tolerant Cyanobacteria as a Tool to Study Terrestrial and Extraterrestrial Iron Deposition

    Science.gov (United States)

    Brown, I. I.; Mummey, D.; Cooksey, K. E.; McKay, D. S.

    2005-01-01

    We are investigating biological mechanisms of terrestrial iron deposition as analogs for Martian hematite recently confirmed by. Possible terrestrial analogs include iron oxide hydrothermal deposits, rock varnish, iron-rich laterites, ferricrete soils, moki balls, and banded iron formations (BIFs). With the discovery of recent volcanic activity in the summit craters of five Martian volcanoes, renewed interest in the iron dynamics of terrestrial hydrothermal environments and associated microorganisms is warranted. In this study we describe a new genus and species of CB exhibiting elevated dissolved iron tolerance and the ability to precipitate hematite on the surface of their exopolymeric sheathes.

  6. [Iron deficiency in the elderly].

    Science.gov (United States)

    Helsen, Tuur; Joosten, Etienne

    2016-06-01

    Anemia is a common diagnosis in the geriatric population, especially in institutionalized and hospitalized elderly. Most common etiologies for anemia in elderly people admitted to a geriatric ward are iron-deficiency anemia and anemia associated with chronic disease. Determination of serum ferritin is the most used assay in the differential diagnosis, despite low sensitivity and moderate specificity. New insights into iron homeostasis lead to new diagnostic assays such as serum hepcidin, serum transferrin receptor and reticulocyte hemoglobin equivalent.Importance of proper diagnosis and treatment for this population is large since there is a correlation between anemia and morbidity - mortality. Anemia is usually defined as hemoglobin less than 12 g/dl for women and less than 13 g/dl for men. There is no consensus for which hemoglobinvalue an investigation into underlying pathology is obligatory. This needs to be evaluated depending on functional condition of the patient.

  7. A new layered iron fluorophosphate

    Indian Academy of Sciences (India)

    Amitava Choudhury

    2002-04-01

    A new iron fluorophosphate of the composition, [C6N4H21] [Fe2F2(HPO4)3][H2PO4]·2H2O, I has been prepared by the hydrothermal route. This compound contains iron fluorophosphate layers and the H2PO$_{4}^{-}$ anions are present in the interlayer space along with the protonated amine and water molecules. The compound crystallizes in the monoclinic space group 21/. ( = 13.4422(10) Å, = 9.7320(10) Å, = 18.3123(3) Å, = 92.1480 °, = 2393.92(5) Å3, = 4, = 719.92, calc = 1.997 g cm-3, 1 = 0.03 and 2 = 0.09).

  8. Avaliação por métodos in vitro e in vivo da biodisponibilidade de sulfato ferroso microencapsulado In vitro and in vivo evaluation of iron bioavailability from microencapsulated ferrous sulfate

    Directory of Open Access Journals (Sweden)

    Maria Lucia Cocato

    2007-06-01

    .1%, 3.4 (standard deviation=0.1% and 3.6 (standard deviation=0.0% for FeSO4.7H2O, Ferlim and Fe0 respectively (p0.05. The absorption percentages of the relative biological value of FeSO4.7H2O were 94.2 (standard deviation=23.8% for the Ferlim group and 79.7 (standard deviation=26.6% for the Fe0 group; the differences were not significant (p>0.05. In numerical values (p>0.05, the Fe0 group presented the lowest mean relative biological value absorption (% and concentration of total iron, heme iron and non-heme iron in the liver. CONCLUSION: Microencapsulation of ferrous sulfate with alginate retains its bioavailability therefore it is a good alternative for the fortification of solid mixtures.

  9. Hereditary iron and copper deposition

    DEFF Research Database (Denmark)

    Aaseth, Jan; Flaten, Trond Peder; Andersen, Ole

    2007-01-01

    Hereditary deposition of iron (primary haemochromatosis) or copper (Wilson's disease) are autosomal recessive metabolic disease characterized by progressive liver pathology and subsequent involvement of various other organs. The prevalence of primary haemochromatosis is approximately 0.5%, about...... can be successfully treated, emphasizing the importance of early diagnosis. Serum ferritin values, transferrin saturation and genetic analysis are used when diagnosing haemochromatosis. The diagnostics of Wilson's disease depends on the use of urinary copper values, serum ceruloplasmin and liver...

  10. Disassembling Iron Availability to Phytoplankton

    OpenAIRE

    2012-01-01

    The bioavailability of iron to microorganisms and its underlying mechanisms have far reaching repercussions to many natural systems and diverse fields of research, including ocean biogeochemistry, carbon cycling and climate, harmful algal blooms, soil and plant research, bioremediation, pathogenesis, and medicine. Within the framework of ocean sciences, short supply and restricted bioavailability of Fe to phytoplankton is thought to limit primary production and curtail atmospheric CO2 drawdow...

  11. Disassembling iron availability to phytoplankton

    OpenAIRE

    2012-01-01

    The bioavailability of iron to microorganisms and its underlying mechanisms have far reaching repercussions to many natural systems and diverse fields of research, including ocean biogeochemistry, carbon cycling and climate, harmful algal blooms, soil and plant research, bioremediation, pathogenesis and medicine. Within the framework of ocean sciences, short supply and restricted bioavailability of Fe to phytoplankton is thought to limit primary production and curtail atmospheric CO2 drawdown...

  12. Iron-Tolerant Cyanobacteria: Ecophysiology and Fingerprinting

    Science.gov (United States)

    Brown, I. I.; Mummey, D.; Lindsey, J.; McKay, D. S.

    2006-01-01

    Although the iron-dependent physiology of marine and freshwater cyanobacterial strains has been the focus of extensive study, very few studies dedicated to the physiology and diversity of cyanobacteria inhabiting iron-depositing hot springs have been conducted. One of the few studies that have been conducted [B. Pierson, 1999] found that cyanobacterial members of iron depositing bacterial mat communities might increase the rate of iron oxidation in situ and that ferrous iron concentrations up to 1 mM significantly stimulated light dependent consumption of bicarbonate, suggesting a specific role for elevated iron in photosynthesis of cyanobacteria inhabiting iron-depositing hot springs. Our recent studies pertaining to the diversity and physiology of cyanobacteria populating iron-depositing hot springs in Great Yellowstone area (Western USA) indicated a number of different isolates exhibiting elevated tolerance to Fe(3+) (up to 1 mM). Moreover, stimulation of growth was observed with increased Fe(3+) (0.02-0.4 mM). Molecular fingerprinting of unialgal isolates revealed a new cyanobacterial genus and species Chroogloeocystis siderophila, an unicellular cyanobacterium with significant EPS sheath harboring colloidal Fe(3+) from iron enriched media. Our preliminary data suggest that some filamentous species of iron-tolerant cyanobacteria are capable of exocytosis of iron precipitated in cytoplasm. Prior to 2.4 Ga global oceans were likely significantly enriched in soluble iron [Lindsay et al, 2003], conditions which are not conducive to growth of most contemporary oxygenic cyanobacteria. Thus, iron-tolerant CB may have played important physiological and evolutionary roles in Earths history.

  13. Iron incorporation and post-malaria anaemia.

    Directory of Open Access Journals (Sweden)

    Conor P Doherty

    Full Text Available BACKGROUND: Iron supplementation is employed to treat post-malarial anaemia in environments where iron deficiency is common. Malaria induces an intense inflammatory reaction that stalls reticulo-endothelial macrophagal iron recycling from haemolysed red blood cells and inhibits oral iron absorption, but the magnitude and duration of these effects are unclear. METHODOLOGY/PRINCIPAL FINDINGS: We examined the red blood cell incorporation of oral administered stable isotopes of iron and compared incorporation between age matched 18 to 36 months old children with either anaemia post-malaria (n = 37 or presumed iron deficiency anaemia alone (n = 36. All children were supplemented for 30 days with 2 mg/kg elemental iron as liquid iron sulphate and administered (57Fe and (58Fe on days 1 and 15 of supplementation respectively. (57Fe and(58Fe incorporation were significantly reduced (8% vs. 28%: p<0.001 and 14% vs. 26%: p = 0.045 in the malaria vs. non-malaria groups. There was a significantly greater haemoglobin response in the malaria group at both day 15 (p = 0.001 and 30 (p<0.000 with a regression analysis estimated greater change in haemoglobin of 7.2 g/l (s.e. 2.0 and 10.1 g/l (s.e. 2.5 respectively. CONCLUSION/SIGNIFICANCE: Post-malaria anaemia is associated with a better haemoglobin recovery despite a significant depressant effect on oral iron incorporation which may indicate that early erythropoetic iron need is met by iron recycling rather than oral iron. Supplemental iron administration is of questionable utility within 2 weeks of clinical malaria in children with mild or moderate anaemia.

  14. Iron, phytoplankton growth, and the carbon cycle.

    Science.gov (United States)

    Street, Joseph H; Paytan, Adina

    2005-01-01

    Iron is an essential nutrient for all living organisms. Iron is required for the synthesis of chlorophyll and of several photosynthetic electron transport proteins and for the reduction of CO2, SO4(2-), and NO3(-) during the photosynthetic production of organic compounds. Iron concentrations in vast areas of the ocean are very low (iron in oxic seawater. Low iron concentrations have been shown to limit primary production rates, biomass accumulation, and ecosystem structure in a variety of open-ocean environments, including the equatorial Pacific, the subarctic Pacific and the Southern Ocean and even in some coastal areas. Oceanic primary production, the transfer of carbon dioxide into organic carbon by photosynthetic plankton (phytoplankton), is one process by which atmospheric CO2 can be transferred to the deep ocean and sequestered for long periods of time. Accordingly, iron limitation of primary producers likely plays a major role in the global carbon cycle. It has been suggested that variations in oceanic primary productivity, spurred by changes in the deposition of iron in atmospheric dust, control atmospheric CO2 concentrations, and hence global climate, over glacial-interglacial timescales. A contemporary application of this "iron hypothesis" promotes the large-scale iron fertilization of ocean regions as a means of enhancing the ability of the ocean to store anthropogenic CO2 and mitigate 21st century climate change. Recent in situ iron enrichment experiments in the HNLC regions, however, cast doubt on the efficacy and advisability of iron fertilization schemes. The experiments have confirmed the role of iron in regulating primary productivity, but resulted in only small carbon export fluxes to the depths necessary for long-term sequestration. Above all, these experiments and other studies of iron biogeochemistry over the last two decades have begun to illustrate the great complexity of the ocean system. Attempts to engineer this system are likely to

  15. Siderophores: More than Stealing Iron

    Directory of Open Access Journals (Sweden)

    Judith Behnsen

    2016-11-01

    Full Text Available Siderophores are small molecular iron chelators that are produced by microbes and whose most notable function is to sequester iron from the host and provide this essential metal nutrient to microbes. Recent studies have proposed additional, noncanonical roles for siderophores, including the acquisition of noniron metals and modulation of host functions. Recently, Holden et al. (V. I. Holden, P. Breen, S. Houle, C. M. Dozois, and M. A. Bachman, mBio 7:e01397-16, 2016, http://dx.doi.org/10.1128/mBio.01397-16 showed that siderophores secreted by Klebsiella pneumoniae during lung infection induce stabilization of the transcription factor HIF-1α, increase the expression of proinflammatory cytokines in the lung, and promote dissemination of K. pneumoniae to the spleen. Thus, their study demonstrated novel roles for siderophores in vivo, beyond iron sequestration. The interaction of siderophores with host cells further promotes the pathogenicity of K. pneumoniae and is likely relevant for other pathogens that also secrete siderophores in the host.

  16. IRON CONTENT OF FOOD COOKED IN IRON UTENSILS: A TRADITIONAL INDIAN WAY

    Directory of Open Access Journals (Sweden)

    Bibifatima Bawakhan

    2016-08-01

    Full Text Available BACKGROUND Since most of the Indian population depends on vegetarian diet, prevalence of iron deficiency status is higher in India compared to other developing countries. In spite of many national programs and treatment options available in correcting this, the incidence is increasing due to poor patient compliance and intolerance to treatment. This study was an effort to show how iron content of Indian food can be increased just by following the traditional way of cooking. OBJECTIVE To compare the iron levels in the Jowar roti cooked in iron and non-iron utensils. METHODOLOGY A cross-sectional study was conducted at KIMS, Hubli. Jowar rotis were prepared from equal quantity of jowar flour in iron and non-iron tawa. Another sample of roti was prepared in iron tawa after treating with lemon juice. Six samples were homogenised and filtered. The filtrates were replicated and analysed for iron levels by FerroZine method. RESULTS In the present study, we found no change in iron levels in the roti prepared in non-iron utensil, 1.45 and 1.94 fold increase in the roti prepared in new iron tawa without water boiled in it and with water boiled in it for dough preparation respectively when compared with iron levels of plain jowar flour. There was 5.77 fold rise in iron levels in lemon juice treated roti which signifies the bioavailability of iron in food. The study showed statistical significance at ‘p’- value < 0.05. CONCLUSION Several studies have shown the similar results and this was done to strengthen the findings in our staple food. Hence, the daily iron requirement can be met easily and effectively by taking the food cooked with lemon juice in iron utensils.

  17. Nitrate-dependent iron oxidation limits iron transport in anoxic ocean regions

    Science.gov (United States)

    Scholz, Florian; Löscher, Carolin R.; Fiskal, Annika; Sommer, Stefan; Hensen, Christian; Lomnitz, Ulrike; Wuttig, Kathrin; Göttlicher, Jörg; Kossel, Elke; Steininger, Ralph; Canfield, Donald E.

    2016-11-01

    Iron is an essential element for life on Earth and limits primary production in large parts of the ocean. Oxygen-free continental margin sediments represent an important source of bioavailable iron to the ocean, yet little of the iron released from the seabed reaches the productive sea surface. Even in the anoxic water of oxygen minimum zones, where iron solubility should be enhanced, most of the iron is rapidly re-precipitated. To constrain the mechanism(s) of iron removal in anoxic ocean regions we explored the sediment and water in the oxygen minimum zone off Peru. During our sampling campaign the water column featured two distinct redox boundaries separating oxic from nitrate-reducing (i.e., nitrogenous) water and nitrogenous from weakly sulfidic water. The sulfidic water mass in contact with the shelf sediment contained elevated iron concentrations >300 nM. At the boundary between sulfidic and nitrogenous conditions, iron concentrations dropped sharply to nitrate reduction (narG). Part of this upregulation was related to the activity of known iron-oxidizing bacteria. Collectively, our data suggest that iron oxidation and removal is induced by nitrate-reducing microbes, either enzymatically through anaerobic iron oxidation or by providing nitrite for an abiotic reaction. Given the important role that iron plays in nitrogen fixation, photosynthesis and respiration, nitrate-dependent iron oxidation likely represents a key-link between the marine biogeochemical cycles of nitrogen, oxygen and carbon.

  18. Deferasirox and deferiprone remove cardiac iron in the iron-overloaded gerbil

    Science.gov (United States)

    WOOD, JOHN C.; OTTO-DUESSEL, MAYA; GONZALEZ, IGNACIO; AGUILAR, MICHELLE I.; SHIMADA, HIRO; NICK, HANSPETER; NELSON, MARVIN; MOATS, REX

    2010-01-01

    Introduction Deferasirox effectively controls liver iron concentration; however, little is known regarding its ability to remove stored cardiac iron. Deferiprone seems to have increased cardiac efficacy compared with traditional deferoxamine therapy. Therefore, the relative efficacy of deferasirox and deferiprone were compared in removing cardiac iron from iron-loaded gerbils. Methods Twenty-nine 8- to 10-week-old female gerbils underwent 10 weekly iron dextran injections of 200 mg/kg/week. Prechelation iron levels were assessed in 5 animals, and the remainder received deferasirox 100 mg/kg/D po QD (n = 8), deferiprone 375 mg/kg/D po divided TID (n = 8), or sham chelation (n = 8), 5 days/week for 12 weeks. Results Deferasirox reduced cardiac iron content 20.5%. No changes occurred in cardiac weight, myocyte hypertrophy, fibrosis, or weight-to-dry weight ratio. Deferasirox treatment reduced liver iron content 51%. Deferiprone produced comparable reductions in cardiac iron content (18.6% reduction). Deferiprone-treated hearts had greater mass (16.5% increase) and increased myocyte hypertrophy. Deferiprone decreased liver iron content 24.9% but was associated with an increase in liver weight and water content. Conclusion Deferasirox and deferiprone were equally effective in removing stored cardiac iron in a gerbil animal model, but deferasirox removed more hepatic iron for a given cardiac iron burden. PMID:17145573

  19. Malabsorption of iron as a cause of iron deficiency anemia in postmenopausal women

    Science.gov (United States)

    Qamar, Khansa; Saboor, Muhammad; Qudsia, Fatima; Khosa, Shafi Muhammad; Moinuddin; Usman, Muhammad

    2015-01-01

    Objective: Malabsorption is one of the causes of iron deficiency anemia in postmenopausal women. The main objective of this study was to access the frequency of malabsorption in iron deficient anemic postmenopausal women. Methods: A total of 123 postmenopausal women were enrolled in the study. Of these 123 women, 50 were included as ‘control group’ and 73 patients with comparable severity of anemia were the ‘patient group’. Two tablets of ferrous sulfate (200 mg/tablet) along with one tablet of vitamin C (500 mg) were given to all participants. Serum iron levels were determined on samples collected from all participants before and after the administration of ferrous sulfate. Difference between before and after serum iron levels of normal and patients were compared. Results: No change in serum iron between sample one and sample two represented malabsorption. Out of 73, 5 postmenopausal anemic patients showed no change in their serum iron level after the administration of ferrous sulfate. This study shows that frequency of malabsorption of iron in postmenopausal women is 6.8%. Conclusion: Malabsorption should be considered as a prevalent cause of iron deficiency anemia in postmenopausal women. It should be properly diagnosed and iron response should be monitored properly in postmenopausal women with IDA after oral iron therapy. If a postmenopausal woman does not show any response to oral iron therapy, she should be evaluated for iron loss (blood loss and/or malabsorption). Intravenous route should be used for the administration of iron in these patients. PMID:26101480

  20. Iron overload thalassemic cardiomyopathy: Iron status assessment and mechanisms of mechanical and electrical disturbance due to iron toxicity

    OpenAIRE

    Lekawanvijit, Suree; Chattipakorn, Nipon

    2009-01-01

    Patients with thalassemia major have inevitably suffered from complications of the disease, due to iron overload. Among such complications, cardiomyopathy is the leading cause of morbidity and mortality (63.6% to 71%). The major causes of death in this group of patients are congestive heart failure and fatal cardiac tachyarrhythmias leading to sudden cardiac death. The free radical-mediated pathway is the principal mechanism of iron toxicity. The consequent series of events caused by iron ove...