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1

Effect of supplementation with ferrous sulfate or iron bis-glycinate chelate on ferritin concentration in Mexican schoolchildren: a randomized controlled trial  

PubMed Central

Background Iron deficiency is one of the most common nutritional deficiencies worldwide. It is more prevalent when iron requirements are increased during pregnancy and during growth spurts of infancy and adolescence. The last stage in the process of iron depletion is characterized by a decrease in hemoglobin concentration, resulting in iron deficiency anemia. Iron deficiency, even before it is clinically identified as anemia, compromises the immune response, physical capacity for work, and intellectual functions such as attention level. Therefore, interventions addressing iron deficiency should be based on prevention rather than on treatment of anemia. The aim of this study was to compare short- and medium-term effects on ferritin concentration of daily supplementation with ferrous sulfate or iron bis-glycinate chelate in schoolchildren with iron deficiency but without anemia. Methods Two hundred schoolchildren from public boarding schools in Mexico City who had low iron stores as assessed by serum ferritin concentration but without anemia were randomly assigned to a daily supplement of 30 mg/day of elemental iron as ferrous sulfate or iron bis-glycinate chelate for 12 weeks. Iron status was evaluated at baseline, one week post-supplementation (short term), and 6 months (medium term) after supplementation. Results Ferritin concentration increased significantly between baseline and post-supplementation as well as between baseline and 6 months after supplementation. One week post-supplementation no difference was found in ferritin concentration between iron compounds, but 6 months after supplementation ferritin concentration was higher in the group that received bis-glycinate chelate iron. However, there is no difference in the odds for low iron storage between 6 months after supplementation versus the odds after supplementation; nor were these odds different by type of supplement. Hemoglobin concentration did not change significantly in either group after supplementation. Conclusions Supplementing with 30 mg/d of elementary iron, either as ferrous sulfate or iron bis-glycinate chelate for 90 days, showed positive effects on increasing ferritin concentration in schoolchildren with low iron stores, and this effect persisted 6 months after supplementation. PMID:25023784

2014-01-01

2

Opinion on certain bisglycinates as sources of copper, zinc, calcium, magnesium and glycinate nicotinate as source of chromium in foods intended for the general population (including food supplements) and foods for particular nutritional uses1 Scientific Opinion of the Scientific Panel on Food Additives, Flavourings, Processing Aids and Materials in Contact with Food  

Microsoft Academic Search

SUMMARY Following a request from the European Commission, the Panel on Food Additives, Flavourings, Processing Aids and Materials in Contact with Food (AFC) was asked to deliver a scientific opinion on the use of copper bisglycinate chelate and chromium glycinate nicotinate as sources for respectively copper and chromium added for nutritional purposes to food supplements, and of calcium bisglycinate chelate

F. Aguilar; H. Autrup; S. Barlow; L. Castle; R. Crebelli; W. Dekant; K.-H. Engel; N. Gontard; D. Gott; S. Grilli; R. Gürtler; C. Larsen; C. Leclercq; F. X. Malcata; W. Mennes; M.-R. Milana; I. Pratt; I. Rietjens; P. Tobback

3

Comparative Study of Gastrointestinal Tract and Liver Toxicity of Ferrous Sulfate, Iron Amino Chelate and Iron Polymaltose Complex in Normal Rats  

Microsoft Academic Search

Iron deficiency is a common worldwide problem leading to several morbidities including anemia. Although oral iron is the first choice in iron deficiency therapy, it may produce gastrointestinal (GI) and liver disorders. The aim of our study was to evaluate: (1) acute toxicity (LD50) in different oral iron compounds such as ferrous sulfate (FS), iron amino chelate (AC) and iron

Jorge E. Toblli; Gabriel Cao; Leda Olivieri; Margarita Angerosa

2008-01-01

4

Modulation of Wnt\\/?-catenin signaling and proliferation by a ferrous iron chelator with therapeutic efficacy in genetically engineered mouse models of cancer  

Microsoft Academic Search

Using a screen for Wnt\\/?-catenin inhibitors, a family of 8-hydroxyquinolone derivatives with in vivo anti-cancer properties was identified. Analysis of microarray data for the lead compound N-((8-hydroxy-7-quinolinyl) (4-methylphenyl)methyl)benzamide (HQBA) using the Connectivity Map database suggested that it is an iron chelator that mimics the hypoxic response. HQBA chelates Fe2+ with a dissociation constant of ?10?19 M, with much weaker binding

G S Coombs; A A Schmitt; C A Canning; A Alok; I C C Low; N Banerjee; S Kaur; V Utomo; C M Jones; S Pervaiz; E J Toone; D M Virshup

2012-01-01

5

Structural, optical and dielectric studies of novel non-linear Bisglycine Lithium Nitrate piezoelectric single crystal  

NASA Astrophysics Data System (ADS)

The novel non-linear semiorganic Bisglycine Lithium Nitrate (BGLiN) single crystals were grown by slow evaporation technique. The structural analysis revealed that it belongs to non-centrosymmetric orthorhombic structure. The presence of various functional groups in the grown crystal was confirmed by FTIR and Raman analysis. Surface morphology of the grown crystal was studied by scanning electron microscopy. The optical studies show that crystal has good transmittance (more than 80%) in the entire visible region and a wide band gap (5.17 eV). The optical constants such as extinction coefficient (K), the reflectance (R) and refractive index (n) as a function of photon energy were calculated from the optical measurements. With the help of these optical constants the electric susceptibility (?c) and both the real (?r) and imaginary (?i) parts of the dielectric constants were also calculated which are required to develop optoelectronic devices. In photoluminescence studies, a broad emission band centered at 404 nm was found in addition to a small band at 352 nm. A broad transition (from 29 to 33 °C) was observed with low dielectric constant value. A high piezoelectric charge coefficient (d33) of 14 pC/N was measured at room temperature which implies its usefulness for various sensor applications. The second harmonic generation efficiency of crystal was found to be 1.5 times to that of KDP. From thermo gravimetric analysis and differential thermal analysis, thermal stability and melting point (246 °C) were investigated. The dielectric behavior, optical characterization, piezoelectric behavior and the non-linear optical properties of the Bisglycine Lithium Nitrate single crystals were reported for the first time which established the usefulness of these crystals for various piezo- and opto-electronics applications.

Dalal, Jyoti; Sinha, Nidhi; Kumar, Binay

2014-11-01

6

21 CFR 184.1315 - Ferrous sulfate.  

Code of Federal Regulations, 2010 CFR

... O, CAS Reg. No. 7782-63-0) is prepared by the action of sulfuric acid on iron. It occurs as pale, bluish-green crystals or granules. Progressive heating of ferrous sulfate heptahydrate produces ferrous sulfate (dried). Ferrous...

2010-04-01

7

21 CFR 184.1315 - Ferrous sulfate.  

... O, CAS Reg. No. 7782-63-0) is prepared by the action of sulfuric acid on iron. It occurs as pale, bluish-green crystals or granules. Progressive heating of ferrous sulfate heptahydrate produces ferrous sulfate (dried). Ferrous...

2014-04-01

8

21 CFR 184.1311 - Ferrous lactate.  

Code of Federal Regulations, 2013 CFR

...crystalline mass. It is prepared by reacting calcium lactate or sodium lactate with ferrous sulfate, direct reaction of lactic acid with iron filings, reaction of ferrous chloride with sodium lactate, or reaction of ferrous sulfate with...

2013-04-01

9

21 CFR 184.1311 - Ferrous lactate.  

Code of Federal Regulations, 2012 CFR

...crystalline mass. It is prepared by reacting calcium lactate or sodium lactate with ferrous sulfate, direct reaction of lactic acid with iron filings, reaction of ferrous chloride with sodium lactate, or reaction of ferrous sulfate with...

2012-04-01

10

21 CFR 184.1311 - Ferrous lactate.  

...crystalline mass. It is prepared by reacting calcium lactate or sodium lactate with ferrous sulfate, direct reaction of lactic acid with iron filings, reaction of ferrous chloride with sodium lactate, or reaction of ferrous sulfate with...

2014-04-01

11

Growth and characterization of bis-glycine sodium nitrate (BGSN), a novel semi-organic nonlinear optical crystal  

NASA Astrophysics Data System (ADS)

Single crystals of bis-glycine sodium nitrate (BGSN), a semi-organic nonlinear optical (NLO) material, have been grown by slow cooling method. Good optical quality single crystals with dimensions up to 1.6×1.6×1.0 cm 3 are obtained. Using a single-crystal diffractometer, the morphology of BGSN crystal was identified. Powder X-ray diffraction confirms the crystalline nature of BGSN. The grown crystals were characterized by optical transmission spectrum (UV) and FTIR studies. The NLO property of the crystal was confirmed by Kurtz second harmonic generation (SHG) test, and the output power generated by the crystal was compared with that of KDP. The thermal stability of the crystal was studied by thermo-gravimetric analysis (TGA), differential thermal analysis (DTA) and differential scanning calorimetry (DSC). Micro hardness study was carried out for different planes, and the anisotropy behavior of the crystal was observed.

Sankar, R.; Ragahvan, C. M.; Mohan Kumar, R.; Jayavel, R.

2007-11-01

12

Study of Vitamins and Dietary Supplements Containing Ferrous Fumarate and Ferrous Sulfate Using Moessbauer Spectroscopy  

SciTech Connect

A study of several samples of vitamins and dietary supplements containing ferrous fumarate and ferrous sulfate was carried out using Moessbauer spectroscopy with a high velocity resolution. A presence of ferrous and ferric impurities was revealed. Small variations of Moessbauer hyperfine parameters were found for both ferrous fumarates and ferrous sulfates in the investigated medicines.

Oshtrakh, M. I. [Faculty of Physical Techniques and Devices for Quality Control, Physical-Technical Department, Ural State Technical University-UPI, Ekaterinburg, 620002 (Russian Federation); Novikov, E. G.; Semionkin, V. A. [Faculty of Physical Techniques and Devices for Quality Control, Physical-Technical Department, Ural State Technical University-UPI, Ekaterinburg, 620002 (Russian Federation); Faculty of Experimental Physics, Physical-Technical Department, Ural State Technical University-UPI, Ekaterinburg, 620002 (Russian Federation); Dubiel, S. M. [Faculty of Physics and Computer Science, AGH University of Science and Technology, PL-30-059 Krakow (Poland)

2010-07-13

13

Study of Vitamins and Dietary Supplements Containing Ferrous Fumarate and Ferrous Sulfate Using Mössbauer Spectroscopy  

NASA Astrophysics Data System (ADS)

A study of several samples of vitamins and dietary supplements containing ferrous fumarate and ferrous sulfate was carried out using Mössbauer spectroscopy with a high velocity resolution. A presence of ferrous and ferric impurities was revealed. Small variations of Mössbauer hyperfine parameters were found for both ferrous fumarates and ferrous sulfates in the investigated medicines.

Oshtrakh, M. I.; Novikov, E. G.; Dubiel, S. M.; Semionkin, V. A.

2010-07-01

14

Wastewater treatment using ferrous sulfate  

SciTech Connect

Treatment of industrial wastewater with coagulants is used extensively in the thorough removal of emulsified tars and oils. The central plant laboratory at the Zhdanov Coke Works conducted investigations of the treatment of wastewater, subsequently used for quenching coke, with ferrous sulfate. Laboratory tests and subsequent industrial tests demonstrated the efficiency of the method. In order to further intensify the wastewater treatment process we conducted laboratory tests with the addition of certain quantities of other coagulation reagents, for example polyacrylamide (PAA) and caustic soda, in addition to the ferrous sulfate. The combined use of polyacrylamide and ferrous sulfate permits instant coagulation of the sludge and very rapid (5 to 10 min) clarification of the water. In addition, in this case the degree of purification of the water is less dependent on the initial concentration of impurities. The purification is also improved when caustic soda is added, raising the pH. From the data it is apparent that an identical degree of purification of the water may be achieved either by increasing the consumption of ferrous sulfate, or by adding PAA or NaOH. During industrial tests of the purification of wastewater with ferrous sulfate, we also investigated the resulting sludge. The use of ferrous sulfate causes a significant increase in its quantity (by a factor of 1.5 to 1.8) and in its oil content (by a factor of 2 to 2.5). The water content in the sludge decreases. The sludge (in the quantity of 0.6% of the charge) may be added to the coking charge.

Boetskaya, K.P.; Ioffe, E.M.

1980-01-01

15

21 CFR 184.1308 - Ferrous gluconate.  

Code of Federal Regulations, 2013 CFR

...greenish-yellow powder or granules. It is prepared by reacting hot solutions of barium or calcium gluconate with ferrous sulfate or by heating freshly prepared ferrous carbonate with gluconic acid in aqueous solution. (b) The ingredient...

2013-04-01

16

21 CFR 184.1308 - Ferrous gluconate.  

...greenish-yellow powder or granules. It is prepared by reacting hot solutions of barium or calcium gluconate with ferrous sulfate or by heating freshly prepared ferrous carbonate with gluconic acid in aqueous solution. (b) The ingredient...

2014-04-01

17

21 CFR 184.1308 - Ferrous gluconate.  

Code of Federal Regulations, 2012 CFR

...greenish-yellow powder or granules. It is prepared by reacting hot solutions of barium or calcium gluconate with ferrous sulfate or by heating freshly prepared ferrous carbonate with gluconic acid in aqueous solution. (b) The ingredient...

2012-04-01

18

21 CFR 184.1308 - Ferrous gluconate.  

Code of Federal Regulations, 2010 CFR

...reacting hot solutions of barium or calcium gluconate with ferrous sulfate or by heating freshly prepared ferrous carbonate with gluconic acid in aqueous solution. (b) The ingredient meets the specifications of the Food Chemcials Codex, 3d Ed....

2010-04-01

19

Hydroxypyridonate chelating agents  

DOEpatents

Chelating agents having 1-hydroxy-2-pyridinone (HOPO) and related moieties incorporated within their structures, including polydentate HOPO-substituted polyamines such as spermidine and spermine, and HOPO-substituted desferrioxamine. The chelating agents are useful in selectively removing certain cations from solution, and are particularly useful as ferric ion and actinide chelators. Novel syntheses of the chelating agents are provided.

Raymond, Kenneth N. (Berkeley, CA); Scarrow, Robert C. (Minneapolis, MN); White, David L. (Oakland, CA)

1987-01-01

20

Hydroxypyridonate chelating agents  

SciTech Connect

Chelating agents are disclosed having 1-hydroxy-2-pyridinone (HOPO) and related moieties incorporated within their structures, including polydentate HOPO-substituted polyamines such as spermidine and spermine, and HOPO-substituted desferrioxamine. The chelating agents are useful in selectively removing certain cations from solution, and are particularly useful as ferric ion and actinide chelators. Novel syntheses of the chelating agents are provided.

Raymond, K.N.; Scarrow, R.C.; White, D.L.

1987-10-06

21

The Rules of Ferrous Metallurgy  

PubMed Central

The ways in which the sciences have been delineated and categorized throughout history provide insights into the formation, stabilization, and establishment of scientific systems of knowledge. The Dresdener school’s approach for explaining and categorizing the genesis of the engineering disciplines is still valid, but needs to be complemented by further-reaching methodological and theoretical reflections. Pierre Bourdieu’s theory of social practice is applied to the question of how individual agents succeed in influencing decisively a discipline’s changing object orientation, institutionalisation and self-reproduction. Through the accumulation of social, cultural and economic capital, they succeed in realising their own organisational ideas and scientific programs. Key concepts for the analysis include the struggle for power and resources, monopolies of interpretation, and the degree of autonomy. A case study from the Aachener Technische Hochschule shows that the consolidation of ferrous metallurgy can be conceived as a symbolical struggle between Fritz Wüst, professor for ferrous metallurgy, and the German Iron and Steel Institute, leading to a construction of a system of differences in which scientists accepted being scientists rather than entrepreneurs, and entrepreneurs accepted becoming entrepreneurs and renounced science.

2010-01-01

22

Chelation in Metal Intoxication  

PubMed Central

Chelation therapy is the preferred medical treatment for reducing the toxic effects of metals. Chelating agents are capable of binding to toxic metal ions to form complex structures which are easily excreted from the body removing them from intracellular or extracellular spaces. 2,3-Dimercaprol has long been the mainstay of chelation therapy for lead or arsenic poisoning, however its serious side effects have led researchers to develop less toxic analogues. Hydrophilic chelators like meso-2,3-dimercaptosuccinic acid effectively promote renal metal excretion, but their ability to access intracellular metals is weak. Newer strategies to address these drawbacks like combination therapy (use of structurally different chelating agents) or co-administration of antioxidants have been reported recently. In this review we provide an update of the existing chelating agents and the various strategies available for the treatment of heavy metals and metalloid intoxications. PMID:20717537

Flora, Swaran J.S.; Pachauri, Vidhu

2010-01-01

23

Heterocyclic dithiocarbazate iron chelators: Fe coordination chemistry and biological activity.  

PubMed

The iron coordination and biological chemistry of a series of heterocyclic dithiocarbazate Schiff base ligands is reported with regard to their activity as Fe chelators for the treatment of Fe overload and also cancer. The ligands are analogous to tridentate heterocyclic hydrazone and thiosemicarbazone chelators we have studied previously which bear NNO and NNS donor sets. The dithiocarbazate Schiff base ligands in this work also are NNS chelators and form stable low spin ferric and ferrous complexes and both have been isolated. In addition an unusual hydroxylated ligand derivative has been identified via an Fe-induced oxidation reaction. X-ray crystallographic and spectroscopic characterisation of these complexes has been carried out and also the electrochemical properties have been investigated. All Fe complexes exhibit totally reversible Fe(III/II) couples in mixed aqueous solvents at potentials higher than found in analogous thiosemicarbazone Fe complexes. The ability of the dithiocarbazate Schiff base ligands to mobilise Fe from cells and also to prevent Fe uptake from transferrin was examined and all ligands were effective in chelating intracellular Fe relative to known controls such as the clinically important Fe chelator desferrioxamine. The Schiff base ligands derived from 2-pyridinecarbaldehyde were non-toxic to SK-N-MC neuroepithelioma (cancer) cells but those derived from the ketones 2-acetylpyridine and di-2-pyridyl ketone exhibited significant antiproliferative activity. PMID:22362375

Basha, Maram T; Chartres, Jy D; Pantarat, Namfon; Ali, Mohammad Akbar; Mirza, Aminul Huq; Kalinowski, Danuta S; Richardson, Des R; Bernhardt, Paul V

2012-06-01

24

Photomixotrophic growth of Rhodobacter capsulatus SB1003 on ferrous iron.  

PubMed

This study investigates the role iron oxidation plays in the purple non-sulfur bacterium Rhodobacter capsulatus SB1003. This organism is unable to grow photoautotrophically on unchelated ferrous iron [Fe(II)] despite its ability to oxidize chelated Fe(II). This apparent paradox was partly resolved by the discovery that SB1003 can grow photoheterotrophically on the photochemical breakdown products of certain ferric iron-ligand complexes, yet whether it could concomitantly benefit from the oxidation of Fe(II) to fix CO(2) was unknown. Here, we examine carbon fixation by stable isotope labeling of the inorganic carbon pool in cultures growing phototrophically on acetate with and without Fe(II). We show that R. capsulatus SB1003, an organism formally thought incapable of phototrophic growth on Fe(II), can actually harness the reducing power of this substrate and grow photomixotrophically, deriving carbon both from organic sources and from fixation of inorganic carbon. This suggests the possibility of a wider occurrence of photoferrotrophy than previously assumed. PMID:22212713

Kopf, S H; Newman, D K

2012-05-01

25

Effects of antacids, ferrous sulfate, and ranitidine on absorption of DR-3355 in humans.  

PubMed Central

This study examined the effects of widely used antacids (aluminum hydroxide, magnesium oxide, and calcium carbonate), ferrous sulfate, and ranitidine on the absorption of a fluorinated quinolone, (-)-(S)-9-fluoro-3-methyl-10-(4-methyl-1-piperazinyl)-7-oxo-2,3-dihydro- 7H- pyrido-[1,2,3,-de][1,4]benzoxazine-6-carboxylic acid hemihydrate (DR-3355), in healthy male volunteers enrolled in three separate randomized crossover studies. Study 1 used 100-mg doses of DR-3355 and concurrent doses of aluminum hydroxide (1 g) or magnesium oxide (500 mg), while study 2 used DR-3355 (100 mg) and concurrent ferrous sulfate (160 mg) or calcium carbonate (1 g). Study 3 used DR-3355 (100 mg) and concurrent ranitidine (150 mg). Each study included control doses of DR-3355 (100 mg) alone. When aluminum hydroxide, ferrous sulfate, and magnesium oxide were coadministered with DR-3355, the relative bioavailability of DR-3355 was decreased to 56, 81, and 78%, respectively, of that for DR-3355 (100 mg) alone. Urinary excretion of DR-3355 was also significantly decreased by coadministration of these drugs. Thus, the magnitude of the decrease in the area under the concentration-time curve for DR-3355 varied among antacids, and the ranking of their inhibitory effects correlated with previously reported rankings of stability constants for chelate formation. DR-3355 bioavailability was not influenced by the concurrent administration of calcium carbonate and ranitidine, indicating that changes in gastric pH do not affect DR-3355 absorption. PMID:1444308

Shiba, K; Sakai, O; Shimada, J; Okazaki, O; Aoki, H; Hakusui, H

1992-01-01

26

21 CFR 73.160 - Ferrous gluconate.  

Code of Federal Regulations, 2010 CFR

...gluconate is the ferrous gluconate defined in the Food Chemicals Codex, 3d Ed. (1981), pp. 122-123, which is incorporated...shall meet the specifications given in the Food Chemicals Codex, 3d Ed. (1981), which is incorporated by reference. The...

2010-04-01

27

Isolation and characterization of Fe(III)-chelate reductase gene LeFRO1 in tomato  

Microsoft Academic Search

Tomato is a model plant for studying molecular mechanisms of iron uptake and metabolism in strategy I plants (dicots and non-graminaceous monocots). Reduction of ferric to ferrous iron on the root surface is an obligatory process for iron acquisition from soil in these plants. LeFRO1 encoding an Fe(III)-chelate reductase protein was isolated from the tomato genome. We show that expression

Lihua Li; Xudong Cheng; Hong-Qing Ling

2004-01-01

28

A comparison of the bioavailability of ferrous fumarate and ferrous sulfate in non-anemic Mexican women and children consuming a sweetened maize and milk drink  

Microsoft Academic Search

Background\\/Objectives:Ferrous fumarate is recommended for the fortification of complementary foods based on similar iron absorption to ferrous sulfate in adults. Two recent studies in young children have reported that it is only 30% as well absorbed as ferrous sulfate. The objective of this study was to compare iron absorption from ferrous fumarate and ferrous sulfate in infants, young children and

M Harrington; C Hotz; C Zeder; G O Polvo; S Villalpando; M B Zimmermann; T Walczyk; J A Rivera; R F Hurrell

2011-01-01

29

Electron microscopy investigations of ferrous martensites  

Microsoft Academic Search

This paper is concerned with electron metallography of bcc or bet ferrous martensite in which particular attention is paid\\u000a to, the characterization of substructures., The transformation substructure is complex and new results are reported on multiple\\u000a {112} twinning. The factors controlling the martensitic substructure are evaluated and it is concluded that the strength and\\u000a deformation, characteristics of martensite are the

Gareth Thomas

1971-01-01

30

Rigid bifunctional chelating agents  

DOEpatents

Bicyclo›2.2.2! octane-2,3 diamine-N,N,N',N'-tetraacetic acids (BODTA) and bicyclo›2.2.1! heptane-2,3 diamine-N,N,N',N'-tetraacetic acid (BHDTA) are chelating agents useful in forming detectably labeled bioconjugate compounds for diagnostic and therapeutic purposes. New compounds and processes of forming BODTA and BHDTA are disclosed. Radioimmunoconjugates of the present invention show high and prolonged tumor uptake with low normal tissue uptakes.

Sweet, Mark P. (Coram, NY); Mease, Ronnie C. (Fairfax, VA); Srivastava, Suresh C. (Setauket, NY)

1998-07-21

31

Rigid bifunctional chelating agents  

DOEpatents

Bicyclo[2.2.2]octane-2,3 diamine-N,N,N',N'-tetraacetic acids (BODTA) and bicyclo[2.2.1]heptane-2,3 diamine-N,N,N',N'-tetraacetic acid (BHDTA) are chelating agents useful in forming detectably labeled bioconjugate compounds for diagnostic and therapeutic purposes. New compounds and processes of forming BODTA and BHDTA are disclosed. Radioimmunoconjugates of the present invention show high and prolonged tumor uptake with low normal tissue uptakes.

Sweet, Mark P. (Coram, NY); Mease, Ronnie C. (Fairfax, VA); Srivastava, Suresh C. (Setauket, NY)

2000-02-08

32

Inhibition of DNA synthesis in CCL 39 cells by impermeable iron chelators.  

PubMed

The synthesis of DNA in CCl 39 cells is inhibited by the presence of the Fe2+ chelator bathophenanthroline disulfonate (BPS) when growth is stimulated by thrombin EGF plus insulin, but not by fetal calf serum. The presence of transferrin and Fe3+ in fetal calf serum can be the basis for lack of BPS effect with serum. The impermeable Fe3+ chelator Tiron does not, by itself, inhibit growth factor induced DNA synthesis, but it induces together with BPS inhibition on fetal calf serum induced DNA synthesis. The combined effect of BPS and Tiron is similar to inhibition of DNA synthesis by impermeable polyvalent DTPA which can chelate both Fe2+ and Fe3+ but does not inhibit ribonucleotide reductase in intact cells. Ferrous iron that bind BPS can relieve the inhibition at stoichiometric concentration. Ferric iron also prevents the inhibition even though it does not bind BPS. BPS does not inhibit DNA synthesis in HeLa cells. BPS reacts with iron from CCl 39 cells but not from HeLa cells. Data show that iron available for impermeable external chelators is in the ferrous state, and that exogenous iron should be reduced before it reverses the inhibition. PMID:9063570

Alcaín, F J; Löw, H; Crane, F L

1997-02-01

33

Ferrous iron oxidation by anoxygenic phototrophic bacteria  

NASA Astrophysics Data System (ADS)

NATURAL oxidation of ferrous to ferric iron by bacteria such as Thiobacillus ferrooxidans or Gallionella ferruginea1, or by chemical oxidation2,3 has previously been thought always to involve molecular oxygen as the electron acceptor. Anoxic photochemical reactions4-6 or a photobiological process involving two photosystems7-9 have also been discussed as mechanisms of ferrous iron oxidation. The knowledge of such processes has implications that bear on our understanding of the origin of Precambrian banded iron formations10-14. The reducing power of ferrous iron increases dramatically at pH values higher than 2-3 owing to the formation of ferric hydroxy and oxyhydroxy compounds1,2,15 (Fig. 1). The standard redox potential of Fe3+/Fe2+ (E0 = +0.77 V) is relevant only under acidic conditions. At pH 7.0, the couples Fe(OH)3/Fe2+ (E'0 = -0.236V) or Fe(OH)3 + HCO-3FeCO3 (E'0 = +0.200 V) prevail, matching redox potentials measured in natural sediments9,16,17. It should thus be possible for Fe(n) around pH 7.0 to function as an electron donor for anoxygenic photosynthesis. The midpoint potential of the reaction centre in purple bacteria is around +0.45 V (ref. 18). Here we describe purple, non-sulphur bacteria that can indeed oxidize colourless Fe(u) to brown Fe(in) and reduce CO2 to cell material, implying that oxygen-independent biological iron oxidation was possible before the evolution of oxygenic photosynthesis.

Widdel, Friedrich; Schnell, Sylvia; Heising, Silke; Ehrenreich, Armin; Assmus, Bernhard; Schink, Bernhard

1993-04-01

34

Natural chelates for radionuclide decorporation  

DOEpatents

This invention relates to the method and resulting chelates of desorbing a radionuclide selected from thorium, uranium, and plutonium containing cultures in a bioavailable form involving pseudomonas or other microorganisms. A preferred microorganism is Pseudomonas aeruginosa which forms multiple chelates with thorium in the range of molecular weight 1000 to 1000 and also forms chelates with uranium of molecular weight in the area of 100 to 1000 and 1000 to 2000.

Premuzic, E.T.

1983-08-25

35

Chelation of cadmium.  

PubMed Central

The toxicity of cadmium is determined by chelation reactions: in vivo, Cd2+ exists exclusively in coordination complexes with biological ligands, or with administered chelating agents. The Cd2+ ion has some soft character, but it is not a typical soft ion. It has a high degree of polarizability, and its complexes with soft ligands have predominantly covalent bond characteristics. Cd2+ forms the most stable complexes with soft donor atoms (S much greater than N greater than 0). The coordination stereochemistry of Cd2+ is unusually varied, including coordination numbers from 2 to 8. Even though the Cd2+ ion is a d10 ion, disturbed coordination geometries are often seen. Generally, the stability of complexes increases with the number of coordination groups contributed by the ligand; consequently, complexes of Cd2+ with polydentate ligands containing SH groups are very stable. Cd2+ in metallothionein (MT) is coordinated with 4 thiolate groups, and the log stability constant is estimated to 25.5. Complexes between Cd2+ and low molecular weight monodentate or bidentate ligands, e.g., free amino acids (LMW-Cd), seem to exist very briefly, and Cd2+ is rapidly bound to high molecular weight proteins, mainly serum albumin. These complexes (HMW-Cd) are rapidly scavenged from blood, mainly by the liver, and Cd2+ is redistributed to MT. After about 1 day the Cd-MT complex (MT-Cd) almost exclusively accounts for the total retained dose of Cd2+, independent of the route of exposure. MT-Cd is slowly transferred to and accumulated in kidney cortex. The acute toxicity and interorgan distribution of parenterally administered Cd2+ are strongly influenced by preceding MT induction, or decreased capacity for MT synthesis; however, the gastrointestinal (GI) uptake of Cd2+ seems unaffected by preceding MT induction resulting in considerable capacity for Cd2+ chelation in intestinal mucosa, and this finding indicates that endogenous MT is not involved in Cd2+ absorption. The toxicity of parenterally administered Cd2+ is strongly enhanced when administered as complexes with NTA or STPP , but it is much decreased when administered as a complex with EDTA. In chronic oral exposure the toxicity and GI uptake of Cd2+ is not changed when Cd2+ is administered as a complex with the detergent formula chelating agents NTA, EDTA and STPP . The uptake of Cd2+ from ligated intestine in vivo was not affected by administration of Cd2+ as complexes with CYS or GSH, but significantly reduced by complexation with EDTA or BAL. The acute toxicity of orally administered Cd2+ is reduced when Cd2+ is administered as a complex with EDTA.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:6734560

Andersen, O

1984-01-01

36

21 CFR 184.1307a - Ferrous ascorbate.  

...ascorbate. (a) Ferrous ascorbate (CAS Reg. No. 24808-52-4) is a reaction product of ferrous hydroxide and ascorbic acid. It is a blue-violet product containing 16 percent iron. (b) The ingredient must be of a purity suitable...

2014-04-01

37

21 CFR 184.1307a - Ferrous ascorbate.  

Code of Federal Regulations, 2013 CFR

...ascorbate. (a) Ferrous ascorbate (CAS Reg. No. 24808-52-4) is a reaction product of ferrous hydroxide and ascorbic acid. It is a blue-violet product containing 16 percent iron. (b) The ingredient must be of a purity suitable...

2013-04-01

38

21 CFR 184.1307a - Ferrous ascorbate.  

Code of Federal Regulations, 2012 CFR

...ascorbate. (a) Ferrous ascorbate (CAS Reg. No. 24808-52-4) is a reaction product of ferrous hydroxide and ascorbic acid. It is a blue-violet product containing 16 percent iron. (b) The ingredient must be of a purity suitable...

2012-04-01

39

Continuous ferrous iron biooxidation in flooded packed bed reactors  

Microsoft Academic Search

In this paper the biological ferrous iron oxidation in flooded packed bed reactors is studied. Bacterial oxidation of ferrous iron is a potential industrial process for the treatment of acid mine drainage and in the regeneration of ferric iron as a leaching agent in hydrometallurgical processes.The aim of this work is the development of a reactor capable of attaining the

A. Mazuelos; R. Romero; I. Palencia; N. Iglesias; F. Carranza

1999-01-01

40

21 CFR 184.1307a - Ferrous ascorbate.  

Code of Federal Regulations, 2011 CFR

...ascorbate. (a) Ferrous ascorbate (CAS Reg. No. 24808-52-4) is a reaction product of ferrous hydroxide and ascorbic acid. It is a blue-violet product containing 16 percent iron. (b) The ingredient must be of a purity suitable...

2011-04-01

41

21 CFR 184.1307a - Ferrous ascorbate.  

Code of Federal Regulations, 2010 CFR

...ascorbate. (a) Ferrous ascorbate (CAS Reg. No. 24808-52-4) is a reaction product of ferrous hydroxide and ascorbic acid. It is a blue-violet product containing 16 percent iron. (b) The ingredient must be of a purity suitable...

2010-04-01

42

Removal of cyanides by complexation with ferrous compounds  

SciTech Connect

Alkaline chlorination, an oxidation process with chlorine (Cl{sub 2}) or hypochlorite (ClO{sup {minus}}), is the most widely accepted method of cyanide treatment. However, removal of cyanide from wastewater to the extent required by the effluent limits imposed by Federal and State regulatory authorities is practically impossible, especially when the majority of the cyanide is present as an iron-cyanide complex. One potential treatment method being further investigated uses ferrous (Fe{sup 2+}) compounds to react with free and complex cyanide ions and produce insoluble iron-cyanide complexes. However, sludges generated by this treatment method contain cyanide wastes which may be considered a hazardous waste by the US Environmental Protection Agency (US EPA). The studies reported in this paper demonstrate that ferrous (Fe{sup 2+}) precipitation can remove cyanide ions (both free and complex) to a concentration within the range of 1 to 2 mg/L. The wastewaters utilized in these tests were collected from a coke plant facility. Synthetic cyanide solutions were used in the studied as well. Ferrous compounds used in the studies included commercial-grade ferrous sulfate, commercial-grade ferrous chloride, and spent pickle liquor (containing ferrous ion). The desired effluent quality was successfully attained in the treatment of the above-mentioned wastewaters by using ferrous compounds as well as spent pickle liquor.

Varuntanya, C.P.; Zabban, W. [Chester Environmental, Moon Township, PA (United States)

1995-12-31

43

Ferrous iron oxidation and rusticyanin in halotolerant, acidophilic 'Thiobacillus prosperus'.  

PubMed

The halotolerant acidophile 'Thiobacillus prosperus' was shown to require chloride for growth. With ferrous iron as substrate, growth occurred at a rate similar to that of the well-studied acidophile Acidithiobacillus ferrooxidans. Previously, the salt (NaCl) requirement of 'T. prosperus' was not clear and its growth on ferrous iron was described as poor. A subtractive hybridization of cDNAs from ferrous-iron-grown and sulfur-grown 'T. prosperus' strain V6 led to identification of a cluster of genes similar to the rus operon reported to encode ferrous iron oxidation in A. ferrooxidans. However, the 'T. prosperus' gene cluster did not contain a homologue of cyc1, which is thought to encode a key cytochrome c in the pathway of electron transport from ferrous iron in A. ferrooxidans. Rusticyanin, another key protein in ferrous iron oxidation by A. ferrooxidans, was present in 'T. prosperus' at similar concentrations in cells grown on either ferrous iron or sulfur. PMID:19332831

Nicolle, James Le C; Simmons, Susan; Bathe, Stephan; Norris, Paul R

2009-04-01

44

Recycling ferrous sulfate via super-oxidant synthesis  

NASA Astrophysics Data System (ADS)

Hydrated ferrous sulfate, a by-product of the titanium-dioxide and steel-surface-treatment industries, is usually disposed of as waste at a significant extra cost for these industries. Due to tight environmental regulations in the European countries, waste disposal of ferrous sulfate will not be an acceptable solution in the near future. Consequently, the waste will have to be treated. Recently, ferrous sulfate was successfully used to synthesize a novel superoxidant material (potassium ferrate) containing iron in hexavalent state (FeVI). With ferrates synthesis, innovative applications are possible in different industrial sectors, such as treatment of water and wastewater and effluent decontamination.

Kanari, N.; Evrard, O.; Neveux, N.; Ninane, L.

2001-11-01

45

Hydroxypyridonate chelating agents and synthesis thereof  

DOEpatents

Chelating agents having 1-hydroxy-2-pyridinone (HOPO) and related moieties incorporated within their structures, including polydentate HOPO-substituted polyamines such as spermidine and spermine, and HOPO-substituted desferrioxamine. The chelating agents are useful in selectively removing certain cations from solution, and are particularly useful as ferric ion and actinide chelators. Novel syntheses of the chelating agents are provided. 4 tabs.

Raymond, K.N.; Scarrow, R.C.; White, D.L.

1985-11-12

46

Chelating Polymers and Environmental Remediation.  

National Technical Information Service (NTIS)

Although there are many approaches to clean up wastewater and soil contaminated with heavy metals and other industrial pollutants, remediation with chelating polymers is one of the most versatile and inexpensive methods. The polymer ligand's efficiency an...

N. E. Zander

2009-01-01

47

Metallic Recovery and Ferrous Melting Processes  

SciTech Connect

The effects of melting atmosphere and charge material type on the metallic and alloy recovery of ferrous charge materials were investigated in two sets of experiments (Tasks 1 and 2). In addition, thermodynamic studies were performed (Task 3) to determine the suitability of ladle treatment for the production of ductile iron using scrap charge materials high in manganese and sulfur. Task 1--In the first set of experiments, the charge materials investigated were thin steel scrap, thick steel scrap, cast iron scrap, and pig iron in the rusty and clean states. Melting atmospheres in this set of experiments were varied by melting with and without a furnace cover. In this study, it was found that neither covered melting nor melting clean (non-rusty) ferrous charge materials improved the metallic recovery over the recovery experienced with uncovered melting or rusty charge materials. However, the silicon and manganese recoveries were greater with covered melting and clean materials. Silicon and manganese in the molten iron react with oxygen dissolved in the iron from uncovered melting and oxidized iron (surface rust). Silica and manganese silicates are formed which float to the slag decreasing recoveries of silicon and manganese. Cast iron and pig iron had higher metallic recoveries than steel scrap. Carbon recovery was affected by the carbon content of the charge materials, and not by the melting conditions. Irons with higher silicon contents had higher silicon recovery than irons with lower silicon contents. Task 2--In the second set of experiments, briquetted turnings and borings were used to evaluate the effects of briquette cleanliness, carbon additions, and melting atmosphere on metallic and alloy recovery. The melting atmosphere in this set of experiments was varied by melting in air and with an argon atmosphere using the SPAL process. In this set of experiments, carbon additions to the briquettes were found to have the greatest effect on metallic and alloy recovery. The use of an argon atmosphere was also found to increase recoveries, but to a lesser extent than with carbon additions to the briquettes. Task 3--Finally, thermodynamic studies were carried out to evaluate the potential for removing manganese and sulfur from iron melts for the production of ferritic ductile iron. Thermodynamic calculations indicated that manganese and sulfur might be removed from iron melts by careful control of the temperature and slag. In laboratory tests however, it was shown that the removal of sulfur was much less successful than that indicated by the thermodynamic analyses.

Luis Trueba

2004-05-30

48

Pulsed laser surface hardening of ferrous alloys.  

SciTech Connect

A high power pulsed Nd:YAG laser and special optics were used to produce surface hardening on 1045 steel and gray cast iron by varying the process parameters. Unlike CO{sub 2} lasers, where absorptive coatings are required, the higher absorptivity of ferrous alloys at the Nd:YAG laser wavelength eliminates the necessity of applying a coating before processing. Metallurgical analysis of the treated tracks showed that very fine and hard martensitic microstructure (1045 steel) or inhomogeneous martensite (gray cast iron) were obtained without surface melting, giving maximum hardness of HRC 61 and HRC 40 for 1045 steel and gray cast iron respectively. The corresponding maximum case depths for both alloys at the above hardness are 0.6 mm. Gray cast iron was more difficult to harden without surface melting because of its lower melting temperature and a significantly longer time-at-temperature required to diffuse carbon atoms from the graphite flakes into the austenite matrix during laser heating. The thermal distortion was characterized in term of flatness changes after surface hardening.

Xu, Z.; Reed, C. B.; Leong, K. H.; Hunter, B. V.

1999-09-30

49

Ferrous iron sorption by hydrous metal oxides.  

PubMed

Ferrous iron is critical to a number of biogeochemical processes that occur in heterogeneous aquatic environments, including the abiotic reductive transformation of subsurface contaminants. The sorption of Fe(II) to ubiquitous soil minerals, particularly iron-free mineral phases, is not well understood. Colloidal TiO2, gamma-AlOOH, and gamma-Al2O2 were used as model hydrous oxides to investigate Fe(II) sorption to iron-free mineral surfaces. Rapid Fe(II) sorption during the first few hours is followed by a much slower uptake process that continues for extended periods (at least 30 days). For equivalent solution conditions, the extent of Fe(II) sorption decreases in the order TiO2 >gamma-Al2O3 >gamma-AlOOH. Short-term equilibrium sorption data measured over a wide range of conditions (pH, ionic strength, Fe(II)-to-sorbent ratio) are well described by the diffuse double layer model. Fe(II) sorption to TiO2 is best described by a single-site model that considers formation of two surface complexes, SOFe+ and SOFeOH0. For gamma-AlOOH and gamma-Al2O3, sorption data are best described by a two-site model that considers formation of SOFe+ complexes at weak- and strong-binding surface sites. Accurate description of sorption data for higher Fe(II) concentrations at alkaline pH conditions requires the inclusion of a Fe(II) surface precipitation reaction in the model formulation. The presence of common groundwater constituents (calcium, sulfate, bicarbonate, or fulvic acid) had no significant effect on Fe(II) sorption. These results demonstrate that iron-free soil minerals can exert a significant influence on Fe(II) sorption and speciation in heterogeneous aquatic systems. PMID:16337955

Nano, Genevieve Villaseñor; Strathmann, Timothy J

2006-05-15

50

Induction of Porphyrin Synthesis in Etiolated Bean Leaves by Chelators of Iron 12  

PubMed Central

Primary leaves of 7- to 9-day-old etiolated seedlings of Phaseolus vulgaris L. var. Red Kidney infiltrated in darkness with aqueous solutions of ?, ??-dipyridyl, o-phenanthroline, pyridine-2-aldoxime, pyridine-2-aldehyde, 8-hydroxyquinoline, or picolinic acid synthesize large amounts of magnesium protoporphyrin monomethyl ester and lesser amounts of magnesium protoporphyrin, protoporphyrin, and protochlorophyllide. Pigment formation proceeds in a linear manner for up to 21 hours after vacuum infiltration with 10 mm ?, ??-dipyridyl. Etiolated tissues of Zea mays L., Cucumis sativus L., and Pisum sativum L. respond in the same way to dipyridyl treatment. Compounds active in eliciting this response are aromatic heterocyclic nitrogenous bases which also act as bidentate chelators and form extremely stable complexes with iron; other metal ion chelators, such as ethylenediaminetetraacetic acid, salicylaldoxime, and sodium diethyldithiocarbamate, do not elicit any pigment synthesis. The ferrous, ferric, cobaltous, and zinc chelates of ?, ??-dipyridyl are similarly ineffective. If levulinic acid is supplied to etiolated bean leaves together with ?, ??-dipyridyl, porphyrin production is inhibited and ?-aminolevulinic acid accumulates in the tissue. Synthesis of porphyrins proceeds in the presence of 450 micrograms per milliliter chloramphenicol or 50 micrograms per milliliter cycloheximide with only partial diminution. We propose that heme or an iron-protein complex blocks the action of the enzyme(s) governing the synthesis of ?-aminolevulinic acid in etiolated leaves in the dark and that iron chelators antagonize this inhibition, leading to the biosynthesis of ?-aminolevulinic acid and porphyrins. PMID:16658677

Duggan, Jeffrey; Gassman, Merrill

1974-01-01

51

The scientific basis for chelation: animal studies and lead chelation.  

PubMed

This presentation summarizes several of the rodent and non-human studies that we have conducted to help inform the efficacy and clinical utility of succimer (meso-2,3-dimercaptosuccincinic acid) chelation treatment. We address the following questions: (1) What is the extent of body lead, and in particular brain lead reduction with chelation, and do reductions in blood lead accurately reflect reductions in brain lead? (2) Can succimer treatment alleviate the neurobehavioral impacts of lead poisoning? And (3) does succimer treatment, in the absence of lead poisoning, produce neurobehavioral deficits? Results from our studies in juvenile primates show that succimer treatment is effective at accelerating the elimination of lead from the body, but chelation was only marginally better than the complete cessation of lead exposure alone. Studies in lead-exposed adult primates treated with a single 19-day course of succimer showed that chelation did not measurably reduce brain lead levels compared to vehicle-treated controls. A follow-up study in rodents that underwent one or two 21-day courses of succimer treatment showed that chelation significantly reduced brain lead levels, and that two courses of succimer were significantly more efficacious at reducing brain lead levels than one. In both the primate and rodent studies, reductions in blood lead levels were a relatively poor predictor of reductions in brain lead levels. Our studies in rodents demonstrated that it is possible for succimer chelation therapy to alleviate certain types of lead-induced behavioral/cognitive dysfunction, suggesting that if a succimer treatment protocol that produced a substantial reduction of brain lead levels could be identified for humans, a functional benefit might be derived. Finally, we also found that succimer treatment produced lasting adverse neurobehavioral effects when administered to non-lead-exposed rodents, highlighting the potential risks of administering succimer or other metal-chelating agents to children who do not have elevated tissue lead levels. It is of significant concern that this type of therapy has been advocated for treating autism. PMID:24113857

Smith, Donald; Strupp, Barbara J

2013-12-01

52

Enhanced NO{sub x} removal in wet scrubbers using metal chelates. Final report, Volume 1  

SciTech Connect

Successful pilot plant tests of simultaneous removal of S0{sub 2} and NO{sub x} in a wet lime flue gas desulfurization system were concluded in December. The tests, at up to 1.5 MW(e) capacity, were conducted by the Cincinnati Gas and Electric Company and Dravo Lime Company for the US Department of Energy at a pilot facility at the Miami Fort station of CG&E near Cincinnati, Ohio. The pilot plant scrubbed a slipstream of flue gas from Unit 7, a 530 MW coal-fired electric generating unit. Tests were conducted in three phases between April and December. The technology tested was wet scrubbing with Thiosorbic{reg_sign} magnesium-enhanced lime for S0{sub 2} removal and simultaneous NO scrubbing with ferrous EDTA, a metal chelate. Magnesium-enhanced lime-based wet scrubbing is used at 20 full-scale high-sulfur coal-fired electric generating units with a combined capacity of 8500 NW. Ferrous EDTA reacts with nitric oxide, NO, which comprises about 95% of NO{sub x} from coal-fired boilers. In this report, although not precise, NO and NO{sub x} are used interchangably. A major objective of the tests was to combine NO{sub x} removal using ferrous EDTA, a developing technology, with SO{sub 2} removal using wet lime FGD, already in wide commercial use. If successful, this could allow wide application of this NO{sub x} removal technology.

Smith, K.; Lani, B.; Berisko, D.; Schultz, C.; Carlson, W. [Dravo Lime Co., Pittsburgh, PA (United States); Benson, L.B. [Radian Corp. (United States)

1992-12-01

53

The ferrous-oxy complex of human aromatase  

SciTech Connect

In this communication, we document the self-assembly of heterologously expressed truncated human aromatase (CYP19) into nanometer scale phospholipids bilayers (Nanodiscs). The resulting P450 CYP19 preparation is stable and can tightly associate with the substrate androstenedione to form a nearly complete high-spin ferric protein. Ferrous CYP19 in Nanodiscs was mixed anaerobically in a rapid-scan stopped-flow with atmospheric dioxygen and the formation of the ferrous-oxy complex observed. First order decay of the oxy-complex to release superoxide and regenerate the ferric enzyme was monitored kinetically. Surprisingly, the ferrous-oxy complex of aromatase is more stable than that of hepatic CYP3A4, opening the path to precisely determine the biochemical and biophysical properties of the reaction cycle intermediates in this important human drug target.

Grinkova, Yelena V.; Denisov, Ilia G. [Department of Biochemistry, Center for Biophysics and Computational Biology, University of Illinois, Urbana, IL 61801 (United States); Waterman, Michael R. [Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232-0146 (United States)], E-mail: michael.waterman@Vanderbilt.Edu; Arase, Miharu; Kagawa, Norio [Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232-0146 (United States); Sligar, Stephen G. [Department of Biochemistry, Center for Biophysics and Computational Biology, University of Illinois, Urbana, IL 61801 (United States)], E-mail: s-sligar@uiuc.edu

2008-07-25

54

Iron chelation and multiple sclerosis  

PubMed Central

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 1?, 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. PMID:24397846

Weigel, Kelsey J.; Lynch, Sharon G.; LeVine, Steven M.

2014-01-01

55

Transport of iron chelators and chelates across MDCK cell monolayers: implications for iron excretion during chelation therapy.  

PubMed

Iron chelators are effective at removing iron from the body in iron overload, but little is known about the handling of iron chelates by the kidney. We studied the transport of deferoxamine, deferasirox, and three hydroxypyridones, and their iron chelates, in polarized renal epithelial MDCK cells growing on Transwell inserts. Directional iron efflux was also studied in (59)Fe-loaded cells. The chelators were transported at comparable rates in the apical and basolateral directions and moved faster than their corresponding chelates, except for deferoxamine, which did not move from the basolateral to the apical side. In contrast, the chelates were transported faster in the apical-to-basolateral direction. More permeable chelators were more efficient at removing iron from iron-loaded cells compared with deferoxamine. Iron is preferentially removed from the basolateral side, and kinetic modeling suggests facilitated diffusion of chelates in some cases. Basolateral iron efflux is temperature-dependent and partially sensitive to ATP depletion. Polarized transport of chelates suggests the kidney may be involved in reabsorption of iron bound to chelators, with a temperature-sensitive facilitated removal of some iron complexes from the basolateral side. Further studies are warranted to determine if these processes may contribute to the observed nephrotoxicity of some iron chelators. PMID:20213118

Huang, Xi-Ping; Thiessen, Jake J; Spino, Michael; Templeton, Douglas M

2010-04-01

56

Controling externalities with asymmetric information: Ferrous Scrap Recycling and the Gold Rush Problem  

E-print Network

Controling externalities with asymmetric information: Ferrous Scrap Recycling and the Gold Rush #12;Controling externalities with asymmetric information: Ferrous Scrap Recycling and the Gold Rush features of the branch. After shedding light on the gold rush problem - the interplay between

Paris-Sud XI, Université de

57

76 FR 9810 - Agency Information Collection Activities: Comment Request for the Ferrous Metals Surveys (17 Forms)  

Federal Register 2010, 2011, 2012, 2013

...Request for the Ferrous Metals Surveys (17 Forms) AGENCY: U.S. Geological Survey...described below. This collection consists of 17 forms. As required by the Paperwork Reduction...1028-0068. Form Number: Various (17 forms). Title: Ferrous Metals...

2011-02-22

58

Luminescent lanthanide chelates and methods of use  

DOEpatents

The invention provides lanthanide chelates capable of intense luminescence. The celates comprise a lanthanide chelator covalently joined to a coumarin-like or quinolone-like sensitizer. Exemplary sensitzers include 2- or 4-quinolones, 2- or 4-coumarins, or derivatives thereof e.g. carbostyril 124 (7-amino-4-methyl-2-quinolone), coumarin 120 (7-amino-4-methyl-2-coumarin), coumarin 124 (7-amino-4-(trifluoromethyl)-2-coumarin), aminomethyltrimethylpsoralen, etc. The chelates form high affinity complexes with lanthanides, such as terbium or europium, through chelator groups, such as DTPA. The chelates may be coupled to a wide variety of compounds to create specific labels, probes, diagnostic and/or therapeutic reagents, etc. The chelates find particular use in resonance energy transfer between chelate-lanthanide complexes and another luminescent agent, often a fluorescent non-metal based resonance energy acceptor. The methods provide useful information about the structure, conformation, relative location and/or interactions of macromolecules.

Selvin, Paul R. (Berkeley, CA); Hearst, John (Berkeley, CA)

1997-01-01

59

21 CFR 184.1307c - Ferrous citrate.  

Code of Federal Regulations, 2010 CFR

...powder or white crystals. It is prepared from the reaction of sodium citrate with ferrous sulfate or by direct action of citric acid on iron filings. (b) The ingredient must be of a purity suitable for its intended use. (c) In...

2010-04-01

60

21 CFR 184.1307c - Ferrous citrate.  

...citrate (iron (II) citrate, (C6 H6 FeO7 ), CAS Reg. No. 23383-11-1) is a slightly colored powder or white crystals. It is prepared from the reaction of sodium citrate with ferrous sulfate or by direct action of citric acid on iron...

2014-04-01

61

21 CFR 184.1307c - Ferrous citrate.  

Code of Federal Regulations, 2013 CFR

...citrate (iron (II) citrate, (C6 H6 FeO7 ), CAS Reg. No. 23383-11-1) is a slightly colored powder or white crystals. It is prepared from the reaction of sodium citrate with ferrous sulfate or by direct action of citric acid on iron...

2013-04-01

62

21 CFR 184.1307c - Ferrous citrate.  

Code of Federal Regulations, 2011 CFR

...citrate (iron (II) citrate, (C6 H6 FeO7 ), CAS Reg. No. 23383-11-1) is a slightly colored powder or white crystals. It is prepared from the reaction of sodium citrate with ferrous sulfate or by direct action of citric acid on iron...

2011-04-01

63

Cu(II) - Catalyzed Hydrazine Reduction of Ferrous Nitrate  

SciTech Connect

This report discusses the results of a study of catalyzed hydrazine reduction of ferrous nitrate. It is apparent that there is a substantial reaction between hydrazine and nitrate ion (or nitric acid) to produce HN3 during both the reduction of Fe(III) and during storage at room temperature.

Karraker, D.G.

2001-10-15

64

LIMESTONE AND LIME NEUTRALIZATION OF FERROUS IRON ACID MINE DRAINAGE  

EPA Science Inventory

The U.S. Environmental Protection Agency conducted a 2-yr study on hydrated lime and rock-dust limestone neutralization of acid mine drainage containing ferrous iron at the EPA Crown Mine Drainage Control Field Site near Rivesville, West Virginia. The study investigated optimizat...

65

Comparative study of Ascofer®; and ferrous gluconate using Mössbauer spectroscopy with a high velocity resolution  

NASA Astrophysics Data System (ADS)

A comparative study of ferrous gluconate as well as fresh and outdated tablets of Ascofer®; was carried out using Mössbauer spectroscopy with a high velocity resolution. The obtained results revealed the presence of three ferrous and one ferric component in all investigated samples which may be related to ferrous gluconate molecules and ferric contamination and/or aging effect.

Oshtrakh, M. I.; Novikov, E. G.; Dubiel, S. M.; Semionkin, V. A.

2014-04-01

66

Ferrous iron-dependent drug delivery enables controlled and selective release of therapeutic  

E-print Network

Ferrous iron-dependent drug delivery enables controlled and selective release of therapeutic agents and cancer. Here, we describe a method to exploit aberrant levels of mobile ferrous iron (Fe parasites produce high concentrations of mobile ferrous iron as a consequence of their catabolism of host

Bogyo, Matthew

67

Dissolution of hematite in acidic oxalate solutions: the effect of ferrous ions addition  

Microsoft Academic Search

Studies on the dissolution of hematite in acidic oxalate solutions have shown that there is a strong relationship between dissolution rates and ferrous ion generation in the solution. The effects of temperature, pH of the solution, oxalate and ferrous ions concentration on the dissolution of hematite in acidic oxalate solutions containing ferrous ions were studied. It was found that the

D. Panias; M. Taxiarchou; I. Douni; I. Paspaliaris; A. Kontopoulos

1996-01-01

68

DETERMINATION OF THE RATES AND PRODUCTS OF FERROUS IRON OXIDATION IN ARSENIC-CONTAMINATED POND WATER.  

EPA Science Inventory

Dissolved ferrous iron and arsenic in the presence of insufficient oxygenated ground water is released into a pond. When the mixing of ferrous iron and oxygenated water within the pond occurs, the ferrous iron is oxidized and precipitated as an iron oxide. Groups of experiments...

69

Chelating agents in biological systems.  

PubMed Central

Chelation enables metals to be transported to or from vulnerable target sites, and to hinder or facilitate their carcinogenic potential. In the reverse sense, metals are capable of ligand scavenging via complexation or mixed complex formation--the latter being the result of interaction with binary complexes. Consequently, metal complexes can be utilized for the transport of selected organic chemotherapeutic drugs to target organs, or for the decorporation of those toxic organic compounds which are able, before or after metabolic activation, of reacting with metals or 1:1 metal complexes. It is emphasized that the degree to which metal ions interact in vivo should employ the conditional constants which take into account competition from other ions, especially Ca2+, H+, and OH-. The genotoxic consequences of the various chemical factors involved in chelation, along with examples: kinetics, stabilization of oxoidation states, lipophilicity, and mixed ligand formation, are discussed. PMID:6791916

Schubert, J

1981-01-01

70

Some Linguistic Detail on Chelation  

NASA Astrophysics Data System (ADS)

The term chelate was first applied by Morgan and Drew in 1920 to describe the heterocyclic rings formed from bidentate ligands bonding to a central atom. The history of the word ch_l_ is traced from its original Greek meaning through the Latin language to its anglicized form, chela. This word has a very rich history and has been cited by both Greek (Aristotle) and Latin (Cicero, Vergil) philosophers and poets.

Haworth, Daniel T.

1998-01-01

71

Phosphonated chelates for nuclear imaging.  

PubMed

A series of bis-, tris- and tetra-phosphonated pyridine ligands is presented. In view of their potential use as chelates for radiopharmaceutical applications, the physico-chemical properties of the ligands and of their Co(ii), Ni(ii), Cu(ii), and Zn(ii) complexes were studied by means of potentiometry and UV-Vis absorption spectroscopy. The pKa values of the ligands and of the complexes, as well as the stability constants for the formation of the complexes, are presented. The kinetic aspects of the formation of Cu(ii) complexes and of their dissociation in acidic media were studied by means of stopped flow experiments, and the stability of the Cu(ii) complex toward reduction to Cu(i) was investigated by cyclic voltammetry and by titration with different reducing agents. The different thermodynamic and kinetic aspects of the polyphosphonated ligands were compared with regard to the impact of the number of phosphonic acid functions. Considering the very promising properties for complexation, preliminary SPECT/CT imaging experiments were carried out on mice with (99m)Tc using the bis- and tetra-phosphonated ligands L(2) and L(1). Finally, a bifunctional version of chelate L(1), L*, was used to label MTn12, a rat monoclonal antibody with both specificity and relatively high affinity for murine tenascin-C. The labeling was monitored by MALDI/MS spectrometry and the affinity of the labeled antibody was checked by immunostaining experiments. After chelation with (99m)Tc, the (99m)Tc-L*-MTn12 antibody was injected into a transgenic mouse with breast cancer and the biodistribution of the labeled antibody was followed by SPECT/CT imaging. PMID:25338628

Abada, Sabah; Lecointre, Alexandre; Christine, Câline; Ehret-Sabatier, Laurence; Saupe, Falk; Orend, Gertraud; Brasse, David; Ouadi, Ali; Hussenet, Thomas; Laquerrière, Patrice; Elhabiri, Mourad; Charbonnière, Loïc J

2014-12-21

72

Chelators for investigating zinc metalloneurochemistry.  

PubMed

The physiology and pathology of mobile zinc signaling has become an important topic in metalloneurochemistry. To study the action of mobile zinc effectively, specialized tools are required that probe the temporal and positional changes of zinc ions within live tissue and cells. In the present article we describe the design and implementation of selective zinc chelators as antagonists to interrogate the function of mobile zinc, with an emphasis on the pools of vesicular zinc in the terminals of hippocampal mossy fiber buttons. PMID:23478014

Radford, Robert J; Lippard, Stephen J

2013-04-01

73

Beliefs about chelation among thalassemia patients  

PubMed Central

Background Understanding patients’ views about medication is crucial to maximize adherence. Thalassemia is a congenital blood disorder requiring chronic blood transfusions and daily iron chelation therapy. Methods The Beliefs in Medicine Questionnaire (BMQ) was used to assess beliefs in chelation in thalassemia patients from North America and London in the Thalassemia Longitudinal Cohort (TLC) of the Thalassemia Clinical Research Network (TCRN). Chelation adherence was based on patient report of doses administered out of those prescribed in the last four weeks. Results Of 371 patients (ages 5-58y, mean 24y), 93% were transfused and 92% receiving chelation (26% deferoxamine (DFO; a slow subcutaneous infusion via portable pump), 63% oral, 11% combination). Patients expressed high “necessity” for transfusion (96%), DFO chelation (92%) and oral chelation (89%), with lower “concern” about treatment (48%, 39%, 19% respectively). Concern about oral chelation was significantly lower than that of DFO (p<0.001). Self-reported adherence to chelation was not associated with views about necessity or concerns, but negatively correlated with perceived sensitivity to DFO (Sensitive Soma scale; r=?0.23, p=0.01) and side effects of oral chelation (r=?0.14, p=0.04). High ferritin iron levels, potentially indicating lower adherence, were found in 41% of patients reporting low necessity of oral chelation compared to 24% reporting high necessity (p=0.048). Concerns about treatment were associated with lower quality of life and more symptoms of anxiety and depression. Conclusions Despite their requirement for multimodal therapy, thalassemia patients have positive views about medicine, more so than in other disease populations. Patients may benefit from education about the tolerability of chelation and strategies to effectively cope with side effects, both of which might be beneficial in lowering body iron burden. Clinicaltrials.gov identifier NCT00661804 PMID:23216870

2012-01-01

74

Exploring copper chelation in Alzheimer's disease protein  

NASA Astrophysics Data System (ADS)

Alzheimer's disease (AD) is a neurodegenerative disorder affecting millions of aging people in the U.S. alone. Clinical studies have indicated that metal chelation is a promising new approach in alleviating the symptoms of AD. Our study explores the as yet undetermined mechanism of copper chelation in amyloid-?, a protein implicated in AD. The structure of amyloid-? is derived from experimental results and incorporates a planar copper-ion-binding structure in a semi-solvated state. We investigate the chelation process using the nudged elastic band method implemented in our ab initio real-space multigrid code. We find that an optimal sequence of unbonding and rebonding events as well as proton transfers are required for a viable chelation process. These findings provide fundamental insight into the process of chelation that may lead to more effective AD therapies.

Rose, Frisco; Hodak, Miroslav; Bernholc, Jerry

2012-02-01

75

Ferrous iron uptake by a magnesium transport system is toxic for Escherichia coli and Salmonella typhimurium.  

PubMed Central

At low magnesium concentrations, Escherichia coli and Salmonella typhimurium LT2 accumulate ferrous iron independent of the ferrous iron transport system feo. Mutant strains with mutations in the magnesium transport gene corA accumulated less ferrous iron than the parent strains. corA+ and corA strains also differed in their sensitivity to ferrous iron under oxic conditions. corA mutants were more resistant to ferrous iron than their parent corA+ strains. Part of the ferrous iron accumulated can be chased by the addition of magnesium. Much less iron was chased when ferric iron was taken up by the siderophore ferrichrome. These results may indicate that the intracellular metabolism of the iron taken up by these systems differs and that it depends on the uptake route of the iron. PMID:9324273

Hantke, K

1997-01-01

76

Inhibitory effect of iron-oxidizing bacteria on ferrous-promoted chalcopyrite leaching  

PubMed

It is generally accepted that iron-oxidizing bacteria, Thiobacillus ferrooxidans, enhance chalcopyrite leaching. However, this article details a case of the bacteria suppressing chalcopyrite leaching. Bacterial leaching experiments were performed with sulfuric acid solutions containing 0 or 0.04 mol/dm3 ferrous sulfate. Without ferrous sulfate, the bacteria enhance copper extraction and oxidation of ferrous ions released from chalcopyrite. However, the bacteria suppressed chalcopyrite leaching when ferrous sulfate was added. This is mainly due to the bacterial consumption of ferrous ions which act as a promoter for chalcopyrite oxidation with dissolved oxygen. Coprecipitation of copper ions with jarosite formed by the bacterial ferrous oxidation also causes the bacterial suppression of copper extraction. Copyright 1999 John Wiley & Sons, Inc. PMID:10397886

Hiroyoshi; Hirota; Hirajima; Tsunekawa

1999-08-20

77

Oral mucosal ulceration due to ferrous sulphate tablets: report of a case.  

PubMed

Recurrent oral ulceration due to underlying iron-deficiency anaemia is already recognized. However, this case report describes a 78-year-old lady who developed severe ulceration of the tongue and floor of the mouth as a result of the treatment of iron-deficiency anaemia with ferrous sulphate tablets. Withdrawal of the ferrous sulphate tablets and replacement with ferrous fumarate syrup led to resolution of the lesion. PMID:17209540

Jones, Terry A; Parmar, Satyesh C

2006-12-01

78

Natural chelating agents for radionuclide decorporation  

DOEpatents

This invention relates to the production of metal-binding compounds useful for the therapy of heavy metal poisoning, for biological mining and for decorporation of radionuclides. The present invention deals with an orderly and effective method of producing new therapeutically effective chelating agents. This method uses challenge biosynthesis for the production of chelating agents that are specific for a particular metal. In this approach, the desired chelating agents are prepared from microorganisms challenged by the metal that the chelating agent is designed to detoxify. This challenge induces the formation of specific or highly selective chelating agents. The present invention involves the use of the challenge biosynthetic method to produce new complexing/chelating agents that are therapeutically useful to detoxify uranium, plutonium, thorium and other toxic metals. The Pseudomonas aeruginosa family of organisms is the referred family of microorganisms to be used in the present invention to produce the new chelating agent because this family is known to elaborate strains resistant to toxic metals.

Premuzic, E.T.

1985-06-11

79

Mercury emission and behavior in primary ferrous metal production  

NASA Astrophysics Data System (ADS)

Ferrous metal production is thought to be a major mercury emission source because it uses large amounts of coal and iron ore, which contain trace amounts of mercury impurities. However, there is limited information about mercury emissions during the production process. In this study, we focused on the coke-oven process, sintering furnace process, and blast furnace process. We measured the mercury concentration in the raw materials, products, and byproducts to estimate the amount of mercury emitted and to investigate the behavior of mercury during the processes. Average mercury concentrations were 30.8 ?g kg -1 in 54 samples of iron ore and 59.9 ?g kg -1 in 33 samples of coal. The total mercury used for ferrous metal production in Japan was estimated to be 8.45 tons in 2005, with 4.07 tons from iron ore, 3.76 tons from coal, and 0.478 tons from limestone. Emissions from the sintering process accounted for more than 90% of the total emissions, and mercury in the exhaust gas was reduced using an activated coke tower and desulfurization equipment installed downstream of an electrostatic precipitator. When byproduct gas generated from coke-oven and blast furnace processes were included, mercury emissions estimates based on actual measurements were 4.08 tons y -1 (in 2005). Thus, about 50% of the mercury input in ferrous metal production was emitted to the atmosphere. The emission factor was calculated as 0.0488 g Hg ton -1 for crude steel production. The introduction of activated coke tower or desulfurization equipment in sintering furnace facilities would reduce mercury emissions.

Fukuda, Naomichi; Takaoka, Masaki; Doumoto, Shingo; Oshita, Kazuyuki; Morisawa, Shinsuke; Mizuno, Tadao

2011-07-01

80

Overview of Lightweight Ferrous Materials: Strategies and Promises  

NASA Astrophysics Data System (ADS)

Reducing the density of steels is a novel approach for weight reduction of automobiles to improve fuel efficiency. In this overview article, strategies for the development of lightweight steels are presented with a focus on bulk ferrous alloys. The metallurgical principles of these steels and their mechanical properties of relevance to automotive applications are discussed. Some of the engineering aspects highlighting the possible problems related to mass production of these steels are also considered. Application prospects of these steels vis-à-vis standard automotive steels are shown.

Rana, Radhakanta; Lahaye, Chris; Ray, Ranjit Kumar

2014-08-01

81

Overview of Lightweight Ferrous Materials: Strategies and Promises  

NASA Astrophysics Data System (ADS)

Reducing the density of steels is a novel approach for weight reduction of automobiles to improve fuel efficiency. In this overview article, strategies for the development of lightweight steels are presented with a focus on bulk ferrous alloys. The metallurgical principles of these steels and their mechanical properties of relevance to automotive applications are discussed. Some of the engineering aspects highlighting the possible problems related to mass production of these steels are also considered. Application prospects of these steels vis-à-vis standard automotive steels are shown.

Rana, Radhakanta; Lahaye, Chris; Ray, Ranjit Kumar

2014-09-01

82

Self-diffusion of iron and sulfur in ferrous sulfide  

Microsoft Academic Search

By use of radiotracer techniques, the iron self-diffusion coefficient in ferrous sulfide single crystals above 620 K was found to be D = D0d exp {-[(81±4) + (84±20)d]\\/RT}where the exponential units are kJ\\/mole, D0 is 1.7± 0.1×10-2 and 3.0±0.2 × 10-2 cm2 sec-1for diffusion in the a- and c-directions, respectively, and d is the deviation from stoichiometry as given in

R. H. Condit; R. R. Hobbins; C. E. Birchenall

1974-01-01

83

Wear study of carbide reinforced P/M ferrous composites  

SciTech Connect

Ferrous alloys have been used for decades as wear resistant materials for applications where severe wear (primarily abrasion) has been a problem. Irons and steels have an advantage in these applications because they can be alloyed with various elements to create structures which are quite harder than the iron matrix. For example, martensitic matrices can be developed as well as carbide structures (consisting usually of Cr-, Nb- or V-based carbides or some other complex carbide structure). However, these materials are usually made through melt/solidification techniques which can sometimes limit the type, volume fraction, and morphology of the carbide. In P/M processing these factors can be ignored in most instances. This paper will discuss the abrasive and impact-abrasive wear behavior of one class of wear resistant materials based on TiC. The materials removal mechanisms will be discussed with emphasis on microstructure-wear interactions. The results will be compared to traditional wear resistant ferrous based alloys.

Hawk, Jeffrey A.; Dogan, Omer N.; Wilson, Rick D.

2000-10-01

84

Analyzing the International Exergy Flow Network of Ferrous Metal Ores  

PubMed Central

This paper employs an un-weighted and weighted exergy network to study the properties of ferrous metal ores in countries worldwide and their evolution from 2002 to 2012. We find that there are few countries controlling most of the ferrous metal ore exports in terms of exergy and that the entire exergy flow network is becoming more heterogeneous though the addition of new nodes. The increasing of the average clustering coefficient indicates that the formation of an international exergy flow system and regional integration is improving. When we contrast the average out strength of exergy and the average out strength of currency, we find both similarities and differences. Prices are affected largely by human factors; thus, the growth rate of the average out strength of currency has fluctuated acutely in the eleven years from 2002 to 2012. Exergy is defined as the maximum work that can be extracted from a system and can reflect the true cost in the world, and this parameter fluctuates much less. Performing an analysis based on the two aspects of exergy and currency, we find that the network is becoming uneven. PMID:25188407

Qi, Hai; An, Haizhong; Hao, Xiaoqing; Zhong, Weiqiong; Zhang, Yanbing

2014-01-01

85

Chelation Therapy and Diamond Blackfan Anemia  

MedlinePLUS

... up in the body, a condition called iron overload. Eventually, after dozens of transfusions, the iron will ... red blood cells that carries oxygen. Fortunately, iron overload and organ damage can be prevented with chelation ...

86

Chelate derivatives as protectors against tissue injury  

US Patent & Trademark Office Database

Derivatives useful in the protection of living organisms against damage due to free radical reactions derived from methoxypolyethylene glycols (MPEG), which are modified by chemically attaching chelating groups in an amide or amine linkage to the nonmethyl end of the polymer. Such chelating groups include ethylene-diamine tetraacetic acid (EDTA), diethylene triamine pentaacetic acid (DTPA), and ethylene glycol aminoethyl ether tetraacetic acid (EGTA), and pharmacologically acceptable salts or esters thereof.

2000-02-01

87

Fluid extraction using carbon dioxide and organophosphorus chelating agents  

DOEpatents

Methods for extracting metalloid and metal species from a solid or liquid material by exposing the material to a fluid solvent, particularly supercritical CO{sub 2}, and a chelating agent are described. The chelating agent forms a chelate with the species, the chelate being soluble in the fluid to allow removal of the species from the material. In preferred embodiments the extraction solvent is supercritical CO{sub 2} and the chelating agent comprises an organophosphorous chelating agent, particularly sulfur-containing organophosphorous chelating agents, including mixtures of chelating agents. Examples of chelating agents include monothiophosphinic acid, di-thiophosphinic acid, phosphine sulfite, phosphorothioic acid, and mixtures thereof. The method provides an environmentally benign process for removing metal and metalloids from industrial waste solutions, particularly acidic solutions. Both the chelate and the supercritical fluid can be regenerated and the contaminant species recovered to provide an economic, efficient process. 1 fig.

Smart, N.G.; Wai, C.M.; Lin, Y.; Kwang, Y.H.

1998-11-24

88

Iron reverses impermeable chelator inhibition of DNA synthesis in CCl 39 cells.  

PubMed

Treatment of Chinese hamster lung fibroblasts (CCl 39 cells) with the impermeable iron(II) chelator bathophenanthroline disulfonate (BPS) inhibits DNA synthesis when cell growth is initiated with growth factors including epidermal growth factor plus insulin, thrombin, or ceruloplasmin, but not with 10% fetal calf serum. The BPS treatment inhibits transplasma membrane electron transport. The treatment leads to release of iron from the cells as determined by BPS iron(II) complex formation over 90 min. Growth factor stimulation of DNA synthesis and electron transport are restored by addition of di- or trivalent iron to the cells in the form of ferric ammonium citrate, ferrous ammonium sulfate, or diferric transferrin. The effect with BPS differs from the inhibition of growth by hydroxyurea, which acts on the ribonucleotide reductase, or diethylenetriaminepentaacetic acid, which is another impermeable chelating agent, in that these agents inhibit growth in 10% fetal calf serum. The BPS effect is consistent with removal of iron from a site on the cell surface that controls DNA synthesis. PMID:8058732

Alcain, F J; Löw, H; Crane, F L

1994-08-16

89

Iron reverses impermeable chelator inhibition of DNA synthesis in CCl 39 cells.  

PubMed Central

Treatment of Chinese hamster lung fibroblasts (CCl 39 cells) with the impermeable iron(II) chelator bathophenanthroline disulfonate (BPS) inhibits DNA synthesis when cell growth is initiated with growth factors including epidermal growth factor plus insulin, thrombin, or ceruloplasmin, but not with 10% fetal calf serum. The BPS treatment inhibits transplasma membrane electron transport. The treatment leads to release of iron from the cells as determined by BPS iron(II) complex formation over 90 min. Growth factor stimulation of DNA synthesis and electron transport are restored by addition of di- or trivalent iron to the cells in the form of ferric ammonium citrate, ferrous ammonium sulfate, or diferric transferrin. The effect with BPS differs from the inhibition of growth by hydroxyurea, which acts on the ribonucleotide reductase, or diethylenetriaminepentaacetic acid, which is another impermeable chelating agent, in that these agents inhibit growth in 10% fetal calf serum. The BPS effect is consistent with removal of iron from a site on the cell surface that controls DNA synthesis. PMID:8058732

Alcain, F J; Löw, H; Crane, F L

1994-01-01

90

Iron Reverses Impermeable Chelator Inhibition of DNA Synthesis in CCl39 Cells  

NASA Astrophysics Data System (ADS)

Treatment of Chinese hamster lung fibro-blasts (CCl 39 cells) with the impermeable iron(II) chelator bathophenanthroline disulfonate (BPS) inhibits DNA synthesis when cell growth is initiated with growth factors including epidermal growth factor plus insulin, thrombin, or ceruloplasmin, but not with 10% fetal calf serum. The BPS treatment inhibits transplasma membrane electron transport. The treatment leads to release of iron from the cells as determined by BPS iron(II) complex formation over 90 min. Growth factor stimulation of DNA synthesis and electron transport are restored by addition of di- or trivalent iron to the cells in the form of ferric ammonium citrate, ferrous ammonium sulfate, or diferric transferrin. The effect with BPS differs from the inhibition of growth by hydroxyurea, which acts on the ribonucleotide reductase, or diethylenetriaminepentaacetic acid, which is another impermeable chelating agent, in that these agents inhibit growth in 10% fetal calf serum. The BPS effect is consistent with removal of iron from a site on the cell surface that controls DNA synthesis.

Alcain, Francisco J.; Low, Hans; Crane, Frederick L.

1994-08-01

91

Clean ferrous casting technology research. Final technical report, September 29, 1993--December 31, 1995  

SciTech Connect

This report details results of a 30-month program to develop methods of making clean ferrous castings, i.e., castings free of inclusions and surface defects. The program was divided into 3 tasks: techniques for producing clean steel castings, electromagnetic removal of inclusions from ferrous melts, and study of causes of metal penetration in sand molds in cast iron.

Piwonka, T.S. [ed.

1996-01-01

92

Ferrous Ferric Chloride Induces the Differentiation of Cultured Mouse Epidermal Melanocytes Additionally with Herbal Medicines  

Microsoft Academic Search

Ferrous ferric chloride (FFC) is a special form of aqueous iron that is a complex of ferrous chloride and ferric chloride and participates in oxidation and reduction reactions. My previous study showed that FFC stimulated the proliferation and differentiation of cultured epidermal melanoblasts or melanocytes derived from newborn mice. However, it is not known whether FFC stimulates the proliferation and

Tomohisa Hirobe

2009-01-01

93

Current use of chelation in American health care.  

PubMed

The National Center for Health Statistics estimates that more than 100,000 Americans receive chelation each year, although far fewer than 1 % of these cases are managed by medical toxicologists. Unfortunately, fatalities have been reported after inappropriate chelation use. There are currently 11 FDA-approved chelators available by prescription although chelation products may also be obtained through compounding pharmacies and directly over the internet. Promotion of chelation training is prominent on some alternative and complementary medicine websites. PMID:24113860

Wax, Paul M

2013-12-01

94

Ferrous versus Ferric Oral Iron Formulations for the Treatment of Iron Deficiency: A Clinical Overview  

PubMed Central

Iron deficiency anaemia represents a major public health problem, particularly in infants, young children, pregnant women, and females with heavy menses. Oral iron supplementation is a cheap, safe, and effective means of increasing haemoglobin levels and restoring iron stores to prevent and correct iron deficiency. Many preparations are available, varying widely in dosage, formulation (quick or prolonged release), and chemical state (ferrous or ferric form). The debate over the advantages of ferrous versus ferric formulations is ongoing. In this literature review, the tolerability and efficacy of ferrous versus ferric iron formulations are evaluated. We focused on studies comparing ferrous sulphate preparations with ferric iron polymaltose complex preparations, the two predominant forms of iron used. Current data show that slow-release ferrous sulphate preparations remain the established and standard treatment of iron deficiency, irrespective of the indication, given their good bioavailability, efficacy, and acceptable tolerability demonstrated in several large clinical studies. PMID:22654638

Santiago, Palacios

2012-01-01

95

Iron (FeII) Chelation, Ferric Reducing Antioxidant Power, and Immune Modulating Potential of Arisaema jacquemontii (Himalayan Cobra Lily)  

PubMed Central

This study explored the antioxidant and immunomodulatory potential of ethnomedicinally valuable species, namely, Arisaema jacquemontii of north-western Himalayan region. The tubers, leaves, and fruits of this plant were subjected to extraction using different solvents. In vitro antioxidant studies were performed in terms of chelation power on ferrous ions and FRAP assay. The crude methanol extract of leaves was found to harbour better chelating capacity (58% at 100??g/mL) and reducing power (FRAP value 1085.4 ± 0.11??MFe3+/g dry wt.) than all the other extracts. The crude methanol extract was thus further partitioned with solvents to yield five fractions. Antioxidant study of fractions suggested that the methanol fraction possessed significant chelation capacity (49.7% at 100??g/mL) and reducing power with FRAP value of 1435.4??M/g dry wt. The fractions were also studied for immune modulating potential where it was observed that hexane fraction had significant suppressive effect on mitogen induced T-cell and B-cell proliferation and remarkable stimulating effect on humoral response by 141% and on DTH response by 168% in immune suppressed mice as compared to the controls. Therefore, it can be concluded that A. jacquemontii leaves hold considerable antioxidant and immunomodulating potential and they can be explored further for the identification of their chemical composition for a better understanding of their biological activities. PMID:24895548

Sudan, Rasleen; Bhagat, Madhulika; Singh, Jasvinder; Koul, Anupurna

2014-01-01

96

SteelMATTER: An Interactive Website for Ferrous Metallurgy  

NSDL National Science Digital Library

SteelMATTER is a "series of interactive educational software resources aimed at helping students understand the key concepts and relationships in ferrous metallurgy." Guided Study is the main section of the site, which describes the six stages of steel production. Starting the guided study can be slightly confusing because of poor site organization; instead of taking users directly to the first stage, an interactive quiz is presented before any material is covered. However, this can easily be bypassed by clicking the Raw Materials link at the bottom of the page. From this point, the site provides a good, step-by-step overview of the processes involved in making steel. There are also numerous Java applets accessible from the main page that simulate many metallurgy processes.

2000-01-01

97

Regulation of the Periplasmic [Fe] Hydrogenase by Ferrous Iron in Desulfovibrio vulgaris (Hildenborough)  

PubMed Central

The periplasmic [Fe] hydrogenase from the sulfate-reducing bacterium Desulfovibrio vulgaris (Hildenborough) DSM 8303 was found to be regulated by ferrous iron availability. During growth with 5 ppm of iron, the enzyme derepressed and the specific activity increased approximately fourfold, whereas the presence of 100 ppm of ferrous iron repressed the enzyme. The repression-derepression phenomenon with ferrous iron was found to be operative when the cells were cultured under either hydrogen or nitrogen gas. This is the first reported case showing that the hydrogenase enzyme is regulated by iron, and the implications of this finding relative to the corrosion industry are discussed. PMID:16348873

Bryant, Richard D.; Van Ommen Kloeke, Fintan; Laishley, Edward J.

1993-01-01

98

Competitive Position of Natural Gas: Ferrous Metal Heat Treating and Atmosphere Generation Applications.  

National Technical Information Service (NTIS)

Market profiles were developed to define current heat treating technologies and to characterize the application and use of each technology in the ferrous metal heat treating industry. Important cost and performance parameters associated with each technolo...

G. S. Koch, H. McDermott, F. H. Klareich

1987-01-01

99

76 FR 31357 - Agency Information Collection Activities: Comment Request for the Ferrous Metals Surveys  

Federal Register 2010, 2011, 2012, 2013

...DEPARTMENT OF THE INTERIOR U.S. Geological Survey [USGS-GX11LR000F60100] Agency Information...Activities: Comment Request for the Ferrous Metals Surveys AGENCY: U.S. Geological Survey (USGS), Interior. ACTION: Notice of a...

2011-05-31

100

Stability of vitamin B1 in Ultra Rice in the presence of encapsulated ferrous fumarate.  

PubMed

Food fortification with iron is effective in combating iron-deficiency anemia. As iron is reactive, it can destroy micronutrients, contribute to poor taste, and discolor the food. Encapsulation could be used to prevent the reaction of iron with food components. The stability of thiamin (vitamin B1) and its effects on organoleptic properties in Ultra Rice were investigated in the presence of encapsulated ferrous fumarate. The preparation of simulated rice grains did not affect the solubility of encapsulated ferrous fumarate in simulated gastric juice. After 20 weeks at 40 degrees C/ approximately 100% relative humidity, essentially all of the vitamin B1 and ferrous iron were retained. Antioxidants were effective in preventing the loss of thiamin and retarding oxidative rancidity catalyzed by ferrous iron. This study demonstrated the feasibility of incorporating both iron and vitamin B1 in a stable Ultra Rice formulation. Inclusion of other stable B vitamins in the formulation should be also feasible. PMID:17886086

Li, Yao; Diosady, Levente L; Jankowski, Shirley

2008-02-01

101

Current approach to iron chelation in children.  

PubMed

Transfusion-dependent children, mostly with thalassaemia major, but also and occasionally to a more significant degree, with inherited bone marrow failures, can develop severe iron overload in early life. Moreover, chronic conditions associated with ineffective erythropoiesis, such as non-transfusion-dependent thalassaemia (NTDT), may lead to iron overload through increased gut absorption of iron starting in childhood. Currently, the goal of iron chelation has shifted from treating iron overload to preventing iron accumulation and iron-induced end-organ complications, in order to achieve a normal pattern of complication-free survival and of quality of life. New chelation options increase the likelihood of achieving these goals. Timely initiation, close monitoring and continuous adjustment are the cornerstones of optimal chelation therapy in children, who have a higher transfusional requirements compared to adults in order to reach haemoglobin levels adequate for normal growth and development. Despite increased knowledge, there are still uncertainties about the level of body iron at which iron chelation therapy should be started and about the appropriate degree of iron stores' depletion. PMID:24646011

Aydinok, Yesim; Kattamis, Antonis; Viprakasit, Vip

2014-06-01

102

Thermal Stability of Chelated Indium Activable Tracers  

SciTech Connect

The thermal stability of indium tracer chelated with organic ligands ethylenediaminetetraacetic acid (EDTA) and nitrilotriacetic acid (NTA) was measured for reservoir temperatures of 150, 200, and 240 C. Measurements of the soluble indium concentration was made as a function of time by neutron activation analysis. From the data, approximate thermal decomposition rates were estimated. At 150 C, both chelated tracers were stable over the experimental period of 20 days. At 200 C, the InEDTA concentration remained constant for 16 days, after which the thermal decomposition occurred at a measured rate constant of k = 0.09 d{sup -1}. The thermal decomposition of InNTA at 200 C showed a first order reaction with a measured rate constant of k = 0.16 d{sup -1}. At 240 C, both indium chelated tracers showed rapid decomposition with rate constants greater than 1.8 d{sup -1}. The data indicate that for geothermal reservoir with temperatures up to about 200 C, indium chelated tracers can be used effectively for transit times of at least 20 days. These experiments were run without reservoir rock media, and do not account for concomitant loss of indium tracer by adsorption processes.

Chrysikopoulos, Costas; Kruger, Paul

1986-01-21

103

Electrochemistry of Metal Chelates in Nonaqueous Media  

Microsoft Academic Search

A systematic account is given of experimental data on the electrochemical coordination reactions of compounds of metals with organic ligands in non-aqueous media. Attention is concentrated on the results of polarographic studies on the so-called inert chelate complexes. The influence of the nature of the metal and the ligand on the mechanism of the electrode reaction is discussed. The bibliography

German K. Budnikov; T. V. Troepol'skaya

1979-01-01

104

New Advances in Iron Chelation Therapy  

Microsoft Academic Search

The emergence of new chelators is likely to have a major impact on the treatment of thalassemia major, sickle cell disease and other hematologic disorders for which regular red cell transfusions are required either to correct severe anemia or to prevent major complications of the underlying disease. In compari- son with deferoxamine, which requires prolonged parenteral infusion to achieve negative

Alan R. Cohen

105

Allylations of chelated enolates using dienyl substrates.  

PubMed

Isomerization-free reactions of dienyl carbonates (1-3) with chelated amino acid ester enolates at -78 degrees C provide important information concerning the mechanism of these dienylations. The formation of regioisomeric products can be explained by competing SN2/SN2' reactions, and the product distribution can be influenced by proper choice of the reaction conditions. PMID:18183999

Basak, Sankar; Kazmaier, Uli

2008-02-01

106

Friction and wear of some ferrous-base metallic glasses  

NASA Technical Reports Server (NTRS)

Sliding friction experiments, X-ray photoelectron spectroscopy (XPS) analysis, and electron microscopy and diffraction studies were conducted with ferrous base metallic glasses (amorphous alloys) in contact with aluminum oxide at temperatures to 750 C in a vacuum. Sliding friction experiments were also conducted in argon and air atmospheres. The results of the investigation indicate that the coefficient of friction increases with increasing temperature to 350 C in vacuum. The increase in friction is due to an increase in adhesion resulting from surface segregation of boric oxide and/or silicon oxide to the surface of the foil. Above 500 C the coefficient of friction decreased rapidly. The decrease correlates with the segregation of boron nitride to the surface. Contaminants can come from the bulk of the material to the surface upon heating and impart boric oxide and/or silicon oxide at 350 C and boron nitride above 500 C. The segregation of contaminants is responsible for the friction behavior. The amorphous alloys have superior wear resistance to crystalline 304 stainless steel. The relative concentrations of the various constituents at the surfaces of the amorphous alloys are very different from the nominal bulk compositions.

Miyoshi, K.; Buckley, D. H.

1983-01-01

107

Friction and wear of some ferrous-base metallic glasses  

NASA Technical Reports Server (NTRS)

Sliding friction experiments, X-ray photoelectron spectroscopy (XPS) analysis, and electron microscopy and diffraction studies were conducted with ferrous base metallic glasses (amorphous alloys) in contact with aluminium oxide at temperatures to 750 C in a vacuum. Sliding friction experiments were also conducted in argon and air atmospheres. The results of the investigation indicate that the coefficient of friction increases with increasing temperature to 350 C in vacuum. The increase in friction is due to an increase in adhesion resulting from surface segregation of boric oxide and/or silicon oxide to the surface of the foil. Above 500 C the coefficient of friction decreased rapidly. The decrease correlates with the segregation of boron nitride to the surface. Contaminants can come from the bulk of the material to the surface upon heating and impart boric oxide and/or silicon oxide at 350 C and boron nitride above 500 C. The segregation of contaminants is responsible for the friction behavior. The amorphous alloys have superior wear resistance to crystalline 304 stainless steel. The relative concentrations of the various constituents at the surfaces of the amorphous alloys are very different from the nominal bulk compositions.

Miyoshi, K.; Buckley, D. H.

1984-01-01

108

Development of cast ferrous alloys for Stirling engine application  

NASA Technical Reports Server (NTRS)

Low cost cast ferrous base alloys that can be used for cylinder and regenerator housing components of the Stirling engine were investigated. The alloys must meet the requirements of high strength and thermal fatigue resistance to approximately 1500 F, compatibility and low permeability with hydrogen, good elevated temperature oxidation/corrosion resistance, and contain a minimum of strategic elements. The phase constituents of over twenty alloy iterations were examined by X-ray diffraction. These alloy candidates were further screened for their tensile and stress rupture strength and surface stability in air at 1450 and 1600 F, respectively. Two alloys, NASAUT 1G (Fe-10Mn-20Cr-1.5C-1.0Si) and NASAUT 4G (Fe-15Mn-12Cr-3Mo-1.5C-1.0Si-1.0Nb), were chosen for more extensive elevated temperature testing. These alloys were found to exhibit nearly equivalent elevated temperature creep strength and oxidation resistance. Silicon present in these alloys at the 1 w/o level permitted the achievement of oxide scale adherence to 1600 F without loss of strength (or ductility) as was noted for equivalent additions of aluminum.

Lemkey, F. D.

1982-01-01

109

Ferrous\\/ferric Mossbauer analysis of simulated nuclear waste glass with and without computer fitting  

Microsoft Academic Search

Wet-chemical and ⁵⁷Fe Mossbauer analyses of ferrous\\/ferric ratios in complex borosilicate and simple silicate glasses were compared. The results support the validity of the colorimetric wet-chemical procedure and establish a linear calibration for the Mossbauer data. The resulting correlation indicates that using area ratios from Mossbauer spectra will overestimate the proportion of ferrous iron by a factor of 1.2. The

DON S. GOLDMAN; DEBORAH E. BEWLEY

1985-01-01

110

Functional characterization of LIT1, the Leishmania amazonensis ferrous iron transporter  

Microsoft Academic Search

Leishmania amazonensis LIT1 was identified based on homology with IRT1, a ferrous iron transporter from Arabidopsis thaliana. ?lit1L. amazonensis are defective in intracellular replication and lesion formation in vivo, a virulence phenotype attributed to defective intracellular iron acquisition. Here we functionally characterize LIT1, directly demonstrating that it functions as a ferrous iron membrane transporter from the ZIP family. Conserved residues

Ismaele Jacques; Norma W. Andrews; Chau Huynh

2010-01-01

111

Matching chelators to radiometals for radiopharmaceuticals.  

PubMed

Radiometals comprise many useful radioactive isotopes of various metallic elements. When properly harnessed, these have valuable emission properties that can be used for diagnostic imaging techniques, such as single photon emission computed tomography (SPECT, e.g.(67)Ga, (99m)Tc, (111)In, (177)Lu) and positron emission tomography (PET, e.g.(68)Ga, (64)Cu, (44)Sc, (86)Y, (89)Zr), as well as therapeutic applications (e.g.(47)Sc, (114m)In, (177)Lu, (90)Y, (212/213)Bi, (212)Pb, (225)Ac, (186/188)Re). A fundamental critical component of a radiometal-based radiopharmaceutical is the chelator, the ligand system that binds the radiometal ion in a tight stable coordination complex so that it can be properly directed to a desirable molecular target in vivo. This article is a guide for selecting the optimal match between chelator and radiometal for use in these systems. The article briefly introduces a selection of relevant and high impact radiometals, and their potential utility to the fields of radiochemistry, nuclear medicine, and molecular imaging. A description of radiometal-based radiopharmaceuticals is provided, and several key design considerations are discussed. The experimental methods by which chelators are assessed for their suitability with a variety of radiometal ions is explained, and a large selection of the most common and most promising chelators are evaluated and discussed for their potential use with a variety of radiometals. Comprehensive tables have been assembled to provide a convenient and accessible overview of the field of radiometal chelating agents. PMID:24173525

Price, Eric W; Orvig, Chris

2014-01-01

112

Mechanism of Ferrous Iron Binding and Oxidation by Ferritin from a Pennate Diatom*  

PubMed Central

A novel ferritin was recently found in Pseudo-nitzschia multiseries (PmFTN), a marine pennate diatom that plays a major role in global primary production and carbon sequestration into the deep ocean. Crystals of recombinant PmFTN were soaked in iron and zinc solutions, and the structures were solved to 1.65–2.2-? resolution. Three distinct iron binding sites were identified as determined from anomalous dispersion data from aerobically grown ferrous soaked crystals. Sites A and B comprise the conserved ferroxidase active site, and site C forms a pathway leading toward the central cavity where iron storage occurs. In contrast, crystal structures derived from anaerobically grown and ferrous soaked crystals revealed only one ferrous iron in the active site occupying site A. In the presence of dioxygen, zinc is observed bound to all three sites. Iron oxidation experiments using stopped-flow absorbance spectroscopy revealed an extremely rapid phase corresponding to Fe(II) oxidation at the ferroxidase site, which is saturated after adding 48 ferrous iron to apo-PmFTN (two ferrous iron per subunit), and a much slower phase due to iron core formation. These results suggest an ordered stepwise binding of ferrous iron and dioxygen to the ferroxidase site in preparation for catalysis and a partial mobilization of iron from the site following oxidation. PMID:23548912

Pfaffen, Stephanie; Abdulqadir, Raz; Le Brun, Nick E.; Murphy, Michael E. P.

2013-01-01

113

Chelation therapy after the Trial to Assess Chelation Therapy: results of a unique trial  

PubMed Central

Purpose of review EDTA chelation therapy has been in off-label use for the treatment of atherosclerosis. We review the results of the first large-scale randomized trial of this treatment. Recent findings The trial to assess chelation therapy was a $30 million National Institutes of Health-funded study of the safety and efficacy of EDTA-based chelation infusions in 1708 post-myocardial infarction (MI) patients. The trial to assess chelation therapy demonstrated a significant (P?=?0.035) 18% reduction in a combined primary endpoint of death, MI, stroke, coronary revascularization, or hospitalization for angina. In diabetic patients the benefit was more extreme, with a 41% relative reduction in risk (P?=?0.0002) and a 43% reduction in total mortality (P?=?0.011). Safety data were favorable. A reduction of oxidative stress by chelation of toxic metals has been proposed as a possible mechanism of action. Summary Recent research suggests that EDTA chelation may be a well-tolerated and effective treatment for post-MI patients. Future replication and mechanistic studies are important prior to implementation in all post-MI patients. PMID:25023079

Avila, Maria D.; Escolar, Esteban; Lamas, Gervasio A.

2014-01-01

114

Cold-Drawn Bioabsorbable Ferrous and Ferrous Composite Wires: An Evaluation of Mechanical Strength and Fatigue Durability  

NASA Astrophysics Data System (ADS)

Yield strengths exceeding 1 GPa with elastic strains exceeding 1 pct were measured in novel bioabsorbable wire materials comprising high-purity iron (Fe), manganese (Mn), magnesium (Mn), and zinc (Zn), which may enable the development of self-expandable, bioabsorbable, wire-based endovascular stents. The high strength of these materials is attributed to the fine microstructure and fiber textures achieved through cold drawing techniques. Bioabsorbable vascular stents comprising nutrient metal compositions may provide a means to overcome the limitations of polymer-based bioabsorbable stents such as excessive strut thickness and poor degradation rate control. Thin, 125- ?m wires comprising combinations of ferrous alloys surrounding a relatively anodic nonferrous core were manufactured and tested using monotonic and cyclic techniques. The strength and durability properties are tested in air and in body temperature phosphate-buffered saline, and then they were compared with cold-drawn 316L stainless steel wire. The antiferromagnetic Fe35Mn-Mg composite wire exhibited more than 7 pct greater elasticity (1.12 pct vs 1.04 pct engineering strain), similar fatigue strength in air, an ultimate strength of more than 1.4 GPa, and a toughness exceeding 35 mJ/mm3 compared with 30 mJ/mm3 for 316L.

Schaffer, Jeremy E.; Nauman, Eric A.; Stanciu, Lia A.

2012-08-01

115

Chelating materials immobilizing carboxymethylated pentaethylenehexamine and polyethyleneimine as ligands.  

PubMed

This article presents an overview of our recent progress on the development of chelating materials. Carboxymethylated pentaethylenehexamine (CM-PEHA) and polyethyleneimine (CM-PEI) as chelating ligands show excellent performance for the solid-phase extraction of trace elements. Chelating resins immobilizing these ligands can be readily prepared by immobilizing PEHA and PEI on methacrylate resins and then carboxymethylating them. Chelating fiber can also be prepared with a wet spinning technique using a mixture of a viscose solution and a solution containing fine particulate CM-PEHA resin or CM-PEI. The potentials of these chelating materials for the separation and preconcentration of trace elements are outlined. PMID:24420242

Kagaya, Shigehiro; Inoue, Yoshinori

2014-01-01

116

Ultrafine Particulate Ferrous Iron and Anthracene Associations with Mitochondrial Dysfunction  

SciTech Connect

The ultrafine size fraction of ambient particles (ultrafine particles, UFP, diameter < 100 nm) has been identified as being far more potent in their adverse health effects than their larger counterparts, yet, the detailed mechanisms for why UFP display such distinctive toxicity are not well understood. In the present study, ambient UFP were exposed to mitochondria while monitoring electron transport chain (ETC) activity as a model system for biochemical toxicity. UFP samples were collected in rural (Ellensburg, WA) and urban environments (Seattle, WA) and chemically characterized for total trace metals, ferrous (Fe(II)) and easily reducible ferric (Fe(III)) iron, polycyclic aromatic hydrocarbons, and surface constituents with X-ray photoelectron spectroscopy (XPS). Low doses of UFP (8 µg mL-1) caused a decrease in mitochondrial ETC function compared to controls in 94% of the samples after The 20 min of exposure. Significant correlations exist between initial %ETC inhibition (0-10 min) and Fe(II) (R=0.55, P=0.03, N=15), anthracene (R=0.74, P<0.01, N=13), and %C-O surface bonds (R=0.56, P=0.03, N=15), whereby anthracene and %C-O correlate as well (R=0.58, P=0.03, N=14). No significant associations were identified with total Fe and other trace metals. Results from this study indicate that the redox active fraction of Fe as well as the abundance of anthracene-related, C-O containing, surface structures may contribute to the initial detrimental behavior of UFP, thus supporting the idea that the Fe(II)/Fe(III) and certain efficient hydroquinone/quinone redox pairs may play an important role likely due to their potential to produce reactive oxygen species (ROS).

Faiola, Celia; Johansen, Anne M.; Rybka, Sara; Nieber, Annika; Thomas-Bradley, Carin; Bryner, Stephanie; Johnston, Justin M.; Engelhard, Mark H.; Nachimuthu, Ponnusamy; Owens, Kalyn S.

2011-04-20

117

Melting of low-level radioactive non-ferrous metal for release  

SciTech Connect

Siempelkamp Nukleartechnik GmbH has gained lots of experience from melting ferrous metals for recycling in the nuclear cycle as well as for release to general reuse. Due to the fact that the world market prices for non-ferrous metals like copper, aluminium or lead raised up in the past and will remain on a high level, recycling of low-level contaminated or activated metallic residues from nuclear decommissioning becomes more important. Based on the established technology for melting of ferrous metals in a medium frequency induction furnace, different melt treatment procedures for each kind of non-ferrous metals were developed and successfully commercially converted. Beside different procedures also different melting techniques such as crucibles, gas burners, ladles etc. are used. Approximately 340 Mg of aluminium, a large part of it with a uranium contamination, have been molten successfully and have met the release criteria of the German Radiation Protection Ordinance. The experience in copper and brass melting is based on a total mass of 200 Mg. Lead melting in a special ladle by using a gas heater results in a total of 420 Mg which could be released. The main goal of melting of non-ferrous metals is release for industrial reuse after treatment. Especially for lead, a cooperation with a German lead manufacturer also for recycling of non releasable lead is being planned. (authors)

Quade, Ulrich; Kluth, Thomas; Kreh, Rainer [Siempelkamp Nukleartechnik GmbH (Germany)

2007-07-01

118

Evaluation of the treatment of chromite ore processing residue by ferrous sulfate and asphalt.  

PubMed

The effectiveness of the treatment of chromite ore processing residue (COPR) with ferrous sulfate and encapsulation into asphalt were explored separately and in combination. The asphalt treatment was conducted by mixing COPR or ferrous sulfate pretreated COPR with varying amounts of asphalt. To assess the efficacy of the treatment, the leachability of toxicity characteristic leaching procedure (TCLP) total chromium (Cr) from all treated samples was determined for curing periods up to 16 months. X-ray absorption near edge structure (XANES) analyses were also performed to evaluate the Cr(6+) concentration in the selected samples. The combination treatment of ferrous sulfate and the encapsulation of the treated COPR into asphalt reduced the TCLP total Cr concentration to lower than the regulatory limit of 5mg/L for Cr contaminated soils, after 16 months. However, the Cr concentrations were still higher than the universal treatment standards (UTS) of 0.6 mg/L for hazardous waste. On the other hand, treatment with ferrous sulfate alone or the encapsulation of the COPR in asphalt failed to meet the TCLP total Cr concentration of 5mg/L, after 16 months. XANES analyses results showed that more than 75% Cr(6+) reduction was achieved upon pretreatment with ferrous sulfate. PMID:18992990

Moon, Deok Hyun; Wazne, Mahmoud; Koutsospyros, Agamemnon; Christodoulatos, Christos; Gevgilili, Halil; Malik, Moinuddin; Kalyon, Dilhan M

2009-07-15

119

Ferrous iron-induced luminol chemiluminescence: a method for hydroxyl radical study.  

PubMed

We have investigated the chemiluminescence signal of the ferrous iron in the presence of the luminol and lucigenin. Ferrous, but not ferric, iron produced a transient signal in the presence of luminol, but not lucigenin. Ferrous iron-induced luminol chemiluminescence was significantly inhibited in a concentration-dependent manner by superoxide dismutase (SOD) and catalase. Specific hydroxyl radical scavengers, mannitol and dimethyl sulfoxide (DMSO), also markedly attenuated the ferrous iron-induced chemiluminescence. Additionally, antioxidants, urate, ascorbate, and methionine produced concentration-dependent significant inhibitions in this chemiluminescence. These results show that the hydroxyl radical generation is dependent on simultaneous formation of superoxide and hydrogen peroxide (H2O2). Ferrous iron does not generate a chemiluminescence signal in the presence of lucigenin suggesting that the formation of a hydroxyl radical is responsible for the luminol chemiluminescence. Thus, the present study has established a simple and inexpensive cell-free screening method for monitoring the scavenging effects of drugs on the hydroxyl radical. PMID:9741393

Yildiz, G; Demiryürek, A T

1998-04-01

120

Evaluation of Ferric and Ferrous Iron Therapies in Women with Iron Deficiency Anaemia  

PubMed Central

Introduction. Different ferric and ferrous iron preparations can be used as oral iron supplements. Our aim was to compare the effects of oral ferric and ferrous iron therapies in women with iron deficiency anaemia. Methods. The present study included 104 women diagnosed with iron deficiency anaemia after evaluation. In the evaluations performed to detect the aetiology underlying the iron deficiency anaemia, it was found and treated. After the detection of the iron deficiency anaemia aetiology and treatment of the underlying aetiology, the ferric group consisted of 30 patients treated with oral ferric protein succinylate tablets (2 × 40?mg elemental iron/day), and the second group consisted of 34 patients treated with oral ferrous glycine sulphate tablets (2 × 40?mg elemental iron/day) for three months. In all patients, the following laboratory evaluations were performed before beginning treatment and after treatment. Results. The mean haemoglobin and haematocrit increases were 0.95?g/dL and 2.62% in the ferric group, while they were 2.25?g/dL and 5.91% in the ferrous group, respectively. A significant difference was found between the groups regarding the increase in haemoglobin and haematocrit values (P < 0.05). Conclusion. Data are submitted on the good tolerability, higher efficacy, and lower cost of the ferrous preparation used in our study. PMID:25006339

Berber, Ilhami; Erkurt, Mehmet Ali; Aydogdu, Ismet; Kuku, Irfan

2014-01-01

121

Iron chelation by polyamidoamine dendrimers: a second-order kinetic model for metal-amine complexation.  

PubMed

This study presents a kinetic model of the chelation of iron ions by generation 4 hydroxyl-terminated polyamidoamine (PAMAM) with ethylenediamine core (G4-OH). The coordination processes of iron ions from ferric chloride, FeCl(3), and ferrous bromide, FeBr(2), to G4-OH dendrimers were analyzed using ultraviolet-visible (UV-vis) spectroscopy, proton nuclear magnetic resonance ((1)H NMR) spectroscopy, and liquid chromatography-mass spectrometry (LC-MS). In the visible region, a charge-transfer was observed when the dendrimer was added to a ferric chloride solution. This phenomenon is a ligand-to-metal charge-transfer (LMCT) between the free electron group of the dendrimer's internal amines and the dehalogenated iron ion that takes 2 h to complete at room temperature. Analysis of potential rate laws and diffusion effects led to a second-order kinetic model for this reaction. By measuring the rate coefficients as a function of temperature (22-37 °C), an apparent activation energy of 41.5 kJ/mol was obtained using the Arrhenius method. The results of this study will fuel research of PAMAM dendrimers for environmental, pharmaceutical, and materials applications. PMID:21995617

Mankbadi, Michael R; Barakat, Mohamed A; Ramadan, Mohamed H; Woodcock, H Lee; Kuhn, John N

2011-11-24

122

Chelators whose affinity for calcium is decreased by illumination  

NASA Technical Reports Server (NTRS)

The present invention discloses a group of calcium chelating compounds which have a descreased affinity for calcium following illumination. These new compounds contain a photolabile nitrobenzyl derivative coupled to a tetracarboxylate Ca.sup.2+ chelating parent compound having the octacoordinate chelating groups characteristic of EGTA or BAPTA. In a first form, the new compounds are comprised of a BAPTA-like chelator coupled to a single 2-nitrobenzyl derivative, which in turn is a photochemical precursor of a 2-nitrosobenzophenone. In a second form, the new compounds are comprised of a BAPTA-like chelator coupled to two 2-nitrobenzyl derivatives, themselves photochemical prcursors of the related 2-nitrosobenzophenones. The present invention also discloses a novel method for preparing 1-hydroxy- or 1-alkoxy-1-(2-nitroaryl)-1-aryl methanes. Methanes of this type are critical to the preparation of, or actually constitute, the photolabile Ca.sup.2+ chelating compounds disclosed and claimed herein.

Tsien, Roger Y. (Inventor); Grynkiewicz, Grzegorz (Inventor); Minta, Akwasi (Inventor)

1987-01-01

123

Electron-transfer reduction of 1-deoxy-1-nitroalditols to glycamines with ferrous hydroxide.  

PubMed

Treatment of eight different 1-deoxy-1-nitroalditols with freshly prepared ferrous hydroxide at ambient temperature provides the corresponding glycamines that were isolated in 81-94% yields as salts with TFA. Under such modified reaction conditions, the retro-Henry reaction of the starting compounds is significantly suppressed due to the amphoteric character of the reducing agent in water. Lower, 58-75% yields were obtained by the classical process with ferrous sulfate in aqueous ammonia and employing an improved purification procedure for the product glycamines by irreversible capture of sulfate ions with barium carbonate. PMID:23123574

Pribulová, Božena; Petrušová, Mária; Smrti?ová, Hana; Petruš, Ladislav

2012-12-01

124

A rapid, simple questionnaire to assess gastrointestinal symptoms after oral ferrous sulphate supplementation  

PubMed Central

Background Oral iron supplementation is often associated with rapid onset of gastrointestinal side-effects. The aim of this study was to develop and trial a short, simple questionnaire to capture these early side-effects and to determine which symptoms are more discriminating. Methods The study was a double-blind placebo-controlled randomized parallel trial with one week treatment followed by one week wash-out. Subjects were randomized into two treatment groups (n?=?10/group) to receive either ferrous sulphate (200 mg capsules containing 65 mg of iron) or placebo, both to be taken at mealtimes twice daily during the treatment period. Subjects completed the questionnaires daily for 14 days. The questionnaire included gastrointestinal symptoms commonly reported to be associated with the oral intake of ferrous iron salts (i.e. nausea, vomiting, heartburn, abdominal pain, diarrhoea, and constipation). Results Seventy five per cent of participants reporting the presence of one or more symptoms in the first week of the study were in the ferrous sulphate group. In the second week of the study (i.e. wash-out), 67% of the participants reporting one or more symptom(s) were in the ferrous sulphate group. In the first week of the study (treatment) the number of symptoms reported by participants in the ferrous sulphate group (mean?±?SEM?=?6.7?±?1.7) was significantly higher than that for participants in the placebo group (1.2?±?0.5) (p?=?0.01). In the second week of the study (wash-out) the number of symptoms reported by participants in the ferrous sulphate group (4.6?±?2.0) appeared higher than for participants in the placebo group (1.0?±?0.7) although this did not reach significance (p?=?0.12). Events for which the gastrointestinal symptom questionnaire was most discriminatory between ferrous sulphate and placebo groups were: heartburn, abdominal pain and the presence of black stools (all p???0.03). Conclusions A tool for the detection of commonly-occurring side effects should not require large study numbers to be effective. With just 10 subjects per group (iron or placebo), this simple questionnaire measures gastrointestinal side-effects associated with oral iron (ferrous sulphate) supplementation, and would be appropriate for use in intervention studies or clinical trials. Trial registration ClinicalTrials.gov Identifier: NCT02146053 (21/05/2014). PMID:24899360

2014-01-01

125

Development of an intelligent control system for ferrous iron oxidation by Thiobacillus ferrooxidans  

SciTech Connect

An intelligent control system (ICS) is being developed for ferrous iron oxidation by Thiobacillus ferroxidans. The ICS provides compterized data acquisition and control of process variables (temperature, Eh, pH, dissolved oxygen and carbon dioxide concentrations, and dilution rate) to maintain the ferrous iron oxidation at the highest possible rate. The ICS uses fuzzy logic for analysis of data inputs and implementation of control strategies. This paper provides preliminary information on the development of the ICS and its operation. 17 refs., 3 figs.

Light, M.D.; Torma, A.E.; Cordes, G.A.

1991-01-01

126

Metal regeneration of iron chelates in nitric oxide scrubbing  

DOEpatents

The present invention relates to a process of using metal particles to reduce NO to NH{sub 3}. More specifically, the invention concerns an improved process to regenerate iron (II) (CHELATE) by reduction of iron (II) (CHELATE) (NO) complex, which process comprises: (a) contacting an aqueous solution containing iron (II) (CHELATE) (NO) with metal particles at between about 20 and 90 C to reduce NO present, produce ammonia or an ammonium ion, and produce free iron (II) (CHELATE) at a pH of between about 3 and 8. The process is useful to remove NO from flue gas and reduce pollution. 34 figs.

Chang, S.G.; Littlejohn, D.; Shi, Y.

1997-08-19

127

Metal-binding polymesr as chelating agents  

E-print Network

nanoparticles (3B) aged at 90 °C for 45 min. x xi List of Tables: Table 1-1: Properties of FDA-approved iron chelators. Table 2-1: Reaction conditions and swelling behavior of hydrogel at pH=6. Table 2-2: Kinetic... and clinical development.20 7 Figure 1-4: Binding interactions between polymeric ammonium compounds and phosphate anions. Reprinted with permission from Elsevier.19 Cross-linked polyallylamine was approved in the United States by the FDA under...

Mohammadi, Zahra

2011-04-11

128

A Comparative Study of Iron Bioavailability from Cocoa Supplemented with Ferric Pyrophosphate or Ferrous Fumarate in Rats  

Microsoft Academic Search

Background: Food iron fortification can be a good strategy to prevent iron deficiency. Iron bioavailability from cocoa powder enriched with ferric pyrophosphate encapsulated in liposomes or ferrous fumarate was assessed in rats. Methods: Three groups of rats consumed during 28 days either a control diet or two diets prepared with ferric pyrophosphate- or ferrous fumarate-enriched cocoa powder as the unique

S. Navas-Carretero; B. Sarriá; A. M. Pérez-Granados; S. Schoppen; M. Izquierdo-Pulido; M. P. Vaquero

2007-01-01

129

Iodine stability in iodized salt dual fortified with microencapsulated ferrous fumarate made by an extrusion-based encapsulation process  

Microsoft Academic Search

The development of a novel, extrusion-based process for making microencapsulated ferrous fumarate for salt double fortification has been reported earlier. This paper focuses on the results of a one-year storage test, specifically the stability of both iodine and ferrous iron in the double fortified salt (DFS) samples prepared using optimal formulations of the iron premix. The study was devised to

Yao O. Li; Levente L. Diosady; Annie S. Wesley

2010-01-01

130

Water Pollution Control Act of 1972. Economic Impacts. Non-Ferrous Metals Industry.  

National Technical Information Service (NTIS)

The requirements of the Federal Water Pollution Control Act Amendments of 1972 will alter the cost structure of non-ferrous smelters and refineries (primarily aluminum, copper, lead and zinc). In the short run, impacted plants may not feel immediate effec...

L. W. Lee, R. A. Leone, C. Smith

1975-01-01

131

Sintering of powder mixtures and the growth of ferrous powder metallurgy  

Microsoft Academic Search

Advances in the understanding of sintering of powder mixtures contributed significantly to the growth of ferrous powder metallurgy industry. Solid-state sintering and liquid-phase activated sintering play an important role in the sintering of powder mixtures. In this paper, sintering of iron powder with graphite; iron powder with copper and graphite; iron powder with nickel and graphite; iron powder with phosphorus;

K. S Narasimhan

2001-01-01

132

A mechanism of abiotic immobilization of nitrate in forest ecosystems: the ferrous wheel hypothesis  

E-print Network

A mechanism of abiotic immobilization of nitrate in forest ecosystems: the ferrous wheel hypothesis Research Center, PO Box 296, Woods Hole, MA 02543, USA, {Department of Soil, Water and Environmental immobilization of nitrate is parti- cularly perplexing because the thermodynamics of nitrate reduction in soils

Chorover, Jon

133

ORGANIC EMISSIONS FROM FERROUS METALLURGICAL INDUSTRIES: COMPILATION OF EMISSION FACTORS AND CONTROL TECHNOLOGIES  

EPA Science Inventory

The report gives results of a review and analysis of the information and data available in the public domain on organic emissions from the ferrous metallurgy industry, specifically the iron and steel, iron foundry, and ferroalloy industries. Emission sources and information gaps ...

134

A kinetic model for biological oxidation of ferrous iron by Thiobacillus ferrooxidans.  

PubMed

The kinetics of bacterial oxidation of ferrous iron in the presence of Thiobacillus ferrooxidans cells were studied using an initial-rate method. Measurements of the redox potential of the solution during the oxidation of ferrous iron were used to assess the initial rate of the reaction. Effects on the rate of reaction were determined for ferrous iron concentration in the range 0.25 to 30 kg m(-3), bacterial concentration in the range 3.25 x 10(7) to 4.47 x 10(8) cells mL(-1), and temperature in the range 20 to 35 degrees C. Using these experimental results and an approach based on Michaelis-Menten kinetics, a model for biological oxidation of ferrous iron was developed. The model, which incorporates terms for the effect of temperature and substrate and cell inhibition, was successfully used to simulate the full range of experimental data obtained. (c) 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 53: 478-486, 1997. PMID:18634043

Nemati, M; Webb, C

1997-03-01

135

Stabilization of Pb and As in soils by applying combined treatment with phosphates and ferrous iron.  

PubMed

The chemical immobilization of Pb and As in contaminated soil from Lavrion, Greece, using monocalcium phosphate and ferrous sulfate as stabilizing agents was investigated. Monocalcium phosphate was added to contaminated soil at PO(4) to Pb molar ratios equal to 0, 0.5, 1, 1.5 and 2.5, whereas ferrous sulfate was added at Fe to As molar ratios equal to 0, 2.5, 5, 10 and 20. Phosphates addition to contaminated soil decreased Pb leachability, but resulted in significant mobilization of As. Simultaneous immobilization of Pb and As was obtained only when soil was treated with mixtures of phosphates and ferrous sulfate. Arsenic uptake by plants was also seen to increase when soil was treated only with phosphates, but co-addition of ferrous sulfate was efficient in maintaining As phytoaccumulation at low levels. The addition of at least 1.5M/M phosphates and 10M/M iron sulfate to soil reduced the dissolved levels of Pb and As in the water extracts to values in compliance with the EU drinking water standards. However, both additives contributed in the acidification of soil, decreasing pH from 7.8 to values as low as 5.6 and induced the mobilization of pH sensitive elements, such as Zn and Cd. PMID:20116921

Xenidis, Anthimos; Stouraiti, Christina; Papassiopi, Nymphodora

2010-05-15

136

Chemical decontamination of process equipment using recyclable chelating agents  

Microsoft Academic Search

The Babcock and Wilcox Company is performing research and development in the application of chelating chemicals to dissolve uranium compounds and other actinide species from the surfaces of DOE process equipment. A chelating system specific for the removal of uranium and other actinides will be applied to the component selected for full-scale demonstration of the process. After application of the

1994-01-01

137

Chelation Treatment for Autism Spectrum Disorders: A Systematic Review  

ERIC Educational Resources Information Center

Chelation treatment is used to eliminate specific metals from the body, such as mercury. It has been hypothesized that mercury poisoning may be a factor in autism and data suggest that perhaps 7% of individuals with autism spectrum disorder (ASD) have received chelation treatment. It would therefore seem timely to review studies investigating the…

Davis, Tonya N.; O'Reilly, Mark; Kang, Soyeon; Lang, Russell; Rispoli, Mandy; Sigafoos, Jeff; Lancioni, Giulio; Copeland, Daelynn; Attai, Shanna; Mulloy, Austin

2013-01-01

138

Reusable chelating resins concentrate metal ions from highly dilute solutions  

NASA Technical Reports Server (NTRS)

Column chromatographic method uses new metal chelating resins for recovering heavy-metal ions from highly dilute solutions. The absorbed heavy-metal cations may be removed from the chelating resins by acid or base washes. The resins are reusable after the washes are completed.

Bauman, A. J.; Weetal, H. H.; Weliky, N.

1966-01-01

139

Clawing Back: Broadening the Notion of Metal Chelators in Medicine  

PubMed Central

The traditional notion of chelation therapy is the administration of a chemical agent to remove metals from the body. But formation of a metal-chelate can have biological ramifications that are much broader than metal elimination. Exploring these other possibilities could lead to pharmacological interventions that alter the concentration, distribution, or reactivity of metals in targeted ways for therapeutic benefit. This review highlights recent examples that showcase four general strategies of using principles of metal chelation in medicinal contexts beyond the traditional notion of chelation therapy. These strategies include altering metal biodistribution, inhibiting specific metalloenzymes associated with disease, enhancing the reactivity of a metal complex to promote cytotoxicity, and conversely, passivating the reactivity of metals by site-activated chelation to prevent cytotoxicity. PMID:23332666

Franz, Katherine J.

2013-01-01

140

Effects of additives and chelating agents on electroless copper plating  

NASA Astrophysics Data System (ADS)

In this study, ethylenediaminetetraacetic acid (EDTA), triethanolamine (TEA), and ethylenediamine (En) were adopted herein as additives or chelating agents in electroless copper plating, with formaldehyde as the reduction agent. Linear sweep voltammetry was successfully applied to analyze the potential shift of copper complexes and the adsorption capability of chelating agents on a surface. Moreover, the grain size and surface roughness of copper were investigated using atomic force microscopy (AFM). The experimental results for a dual-chelating-agent system indicated that EDTA plays an important role in chelating, while the main effect of TEA is adsorption on copper surfaces to inhibit formaldehyde oxidation. Meanwhile, ethylenediamene is a prominent refining agent owing to its markedly higher adsorption strength on copper surfaces than formaldehyde and TEA. The analyses including linear sweep voltammetry, AFM, and XRD are effective to explore the effect of chelating agents and additives on electroless copper plating and deposits.

Lin, Yi-Mao; Yen, Shi-Chern

2001-07-01

141

Chelating versatility of toxic metal resistant microorganisms  

SciTech Connect

Thorium- and uranium-resistant strains of Pseudomonas aeruginosa when grown in high concentration of these metals (100 to 1000 ppM) in citrate- or succinate-containing media produce several chelating agents. Crude extracts of the metal-induced products, when tested for their toxicity and decorporation potential from mammalian tissues have shown that their efficiency is comparable to DTPA (Diethylene triamine pentaacetic acid) and DFOA (Desferrioxamine). Washed biomass of P. aeruginosa also bioaccumulates heavy metals. Bioaccumulation is selective and several microorganisms have been tested for selective adsorption of uranium, thorium, cobalt, chromium, manganese, tin, and platinum. The results have shown that P. aeruginosa CSU has a preference for uranium, while P. aeruginosa PAO-1 and P. fluorescens exhibit a preference for thorium, and Aspergillus niger is selective for chromium and thorium. 8 refs., 3 figs., 2 tabs.

Premuzic, E.T.; Lin, M.

1985-05-01

142

Liposomal Cu-64 labeling method using bifunctional chelators: poly(ethylene glycol) spacer and chelator effects.  

PubMed

Two bifunctional Cu-64 chelators (BFCs), (6-(6-(3-(2-pyridyldithio)propionamido)hexanamido)benzyl)-1,4,8,11-tetraazacyclotetradecane-1,4,8,11-tetraacetic acid (TETA-PDP) and 4-(2-(2-pyridyldithioethyl)ethanamido)-11-carboxymethyl-1,4,8,11-tetraazabicyclo(6.6.2)hexadecane (CB-TE2A-PDEA), were synthesized and conjugated to long-circulating liposomes (LCLs) via attachment to a maleimide lipid. An in vitro stability assay of (64)Cu-TETA, (64)Cu-TETA-PEG2k, and (64)Cu-CB-TE2A-PEG2k liposomes showed that more than 86% of the radioactivity remains associated with the liposomal fraction after 48 h of incubation with mouse serum. The in vivo time activity curves (TAC) for the three liposomal formulations showed that approximately 50% of the radioactivity cleared from the blood pool in 16-18 h. As expected, the in vivo biodistribution and TAC data obtained at 48 h demonstrate that the clearance of radioactivity from the liver slows with the incorporation of a poly(ethylene glycol)-2k (PEG2k) brush. Our data suggest that (64)Cu-TETA and (64)Cu-CB-TE2A are similarly stable in the blood pool and accumulation of radioactivity in the liver and spleen is not related to the stability of Cu-64 chelator complex; however, clearance of Cu-64 from the liver and spleen are faster when injected as (64)Cu-TETA-chelated liposomes rather than (64)Cu-CB-TE2A-chelated liposomes. PMID:20568726

Seo, Jai Woong; Mahakian, Lisa M; Kheirolomoom, Azadeh; Zhang, Hua; Meares, Claude F; Ferdani, Riccardo; Anderson, Carolyn J; Ferrara, Katherine W

2010-07-21

143

Chelation: Harnessing and Enhancing Heavy Metal Detoxification--A Review  

PubMed Central

Toxic metals such as arsenic, cadmium, lead, and mercury are ubiquitous, have no beneficial role in human homeostasis, and contribute to noncommunicable chronic diseases. While novel drug targets for chronic disease are eagerly sought, potentially helpful agents that aid in detoxification of toxic elements, chelators, have largely been restricted to overt acute poisoning. Chelation, that is multiple coordination bonds between organic molecules and metals, is very common in the body and at the heart of enzymes with a metal cofactor such as copper or zinc. Peptides glutathione and metallothionein chelate both essential and toxic elements as they are sequestered, transported, and excreted. Enhancing natural chelation detoxification pathways, as well as use of pharmaceutical chelators against heavy metals are reviewed. Historical adverse outcomes with chelators, lessons learned in the art of using them, and successes using chelation to ameliorate renal, cardiovascular, and neurological conditions highlight the need for renewed attention to simple, safe, inexpensive interventions that offer potential to stem the tide of debilitating, expensive chronic disease. PMID:23690738

Sears, Margaret E.

2013-01-01

144

Possible Association of Ferrous Phosphates and Ferric Sulfates in S-rich Soil on Mars  

NASA Astrophysics Data System (ADS)

NASA Mars Exploration Rover (MER) Spirit explored Gusev Crater to look for signs of ancient aqueous activity, assess past environmental conditions and suitability for life. Spirit excavated light-toned, S-rich soils at several locations. These are likely of hydrothermal, possibly fumarolic origin. At a location dubbed Paso Robles the light-toned soil was also rich in P - a signature from surrounding rock. While S is mainly bound in ferric hydrated sulfates [1], the mineralogy of P is ill-constrained [2]. P is a key element for life and its mineralogy constrains its availability. Ferrous phases observed in Paso Robles Mössbauer spectra may represent olivine and pyroxene from surrounding basaltic soil [1] or ferrous phosphate minerals [3]. Phosphate is well-known to complex and stabilize Fe 2+ against oxidation to Fe 3+ . Schröder et al. [3] proposed a formation pathway of ferrous phosphate/ferric sulfate associations: sulfuric acid reacts with basalt containing apatite, forming CaSO4 and phosphoric acid. The phosphoric and/or excess sulfuric acid reacts with olivine, forming Fe2+-phosphate and sulfate. The phosphate is less soluble and precipitates. Ferrous sulfate remains in solution and is oxidized as pH increases. To verify this pathway, we dissolved Fe2+-chloride and Na-phosphate salts in sulfuric acid inside an anoxic glovebox. The solution was titrated to pH 6 by adding NaOH when a first precipitate formed, which was ferrous phosphate according to Mössbauer spectroscopy (MB). At that point the solution was removed from the glovebox and allowed to evaporate in the presence of atmospheric oxygen, leading to the oxidation of Fe2+. The evaporation rate was controlled by keeping the suspensions at different temperatures; pH was monitored during the evaporation process. The final precipitates were analyzed by MB and X-Ray Fluorescence (XRF), comparable to MER MB and Alpha Particle X-ray Spectrometer instrument datasets, and complementary techniques such as X-ray diffraction. Fourier Transform Infrared spectroscopy measurements to compare to MER miniature thermal emission spectrometer data are planned. We observed differences depending on the heat source during evaporation. The closest match to Martian data on the basis of Mössbauer spectra was achieved with a suspension evaporated at 80°C on a hot plate, i.e. heated from below with a temperature gradient in the bottle. The Fe2+/FeT ratio matched, and ferrous phases were all phosphate. When heated in a water bath, i.e. without a temperature gradient in the bottle, Fe2+/FeT ratios increased and ferrous sulfates precipitated also. These results indicate that the Martian light-toned S-rich deposits formed by evaporation on the surface where temperature gradients would be expected rather than underground. They confirm that ferrous phosphate/ferric sulfate associations are possible on Mars and could be preserved in the oxygen-free Martian atmosphere. References: [1] Morris et al., J.Geophys. Res. 111 (2006) E02S13; [2] Ming et al., J. Geophys. Res. 111 (2006) E02S12; [3] Schröder et al., GSA Annual Meeting 2008, Paper No. 171-3.

Mao, J.; Schroeder, C.; Haderlein, S.

2012-12-01

145

Ferrous arrowheads and their oil quench hardening: Some early Indian evidence  

NASA Astrophysics Data System (ADS)

A wide variety of ferrous arrowheads were in use in ancient India. Several typical chemical analyses of arrowheads found from archaeological excavation carried out at Kaushambi are reported in this paper. The average carbon content of these arrowheads varied from as low as 0.1 wt.% to approximately 0.9 wt.%. Literary evidence for oil quench hardening of ferrous arrowheads, as reported in famous Sanskrit epics—the R?m?yana and the Mah?bh?rata—have been discussed in this paper. This type of quench hardening was intentionally adopted as it helped in preventing distortion and formation of quench cracks in arrowheads. The oil quench-hardened arrowheads were rubbed on stones to sharpen them, which also brought about tempering of martensite due to frictional heat.

Dube, R. K.

2008-05-01

146

Mathematical model of the oxidation of ferrous iron by a biofilm of Thiobacillus ferrooxidans.  

PubMed

Microbial oxidation of ferrous iron may be a viable alternative method of producing ferric sulfate, which is a reagent used for removal of H(2)S from biogas. The paper introduces a kinetic study of the biological oxidation of ferrous iron by Thiobacillus ferrooxidans immobilized on biomass support particles (BSP) composed of polyurethane foam. On the basis of the data obtained, a mathematical model for the bioreactor was subsequently developed. In the model described here, the microorganisms adhere by reversible physical adsorption to the ferric precipitates that are formed on the BSP. The model can also be considered as an expression for the erosion of microorganisms immobilized due to the agitation of the medium by aeration. PMID:12153298

Mesa, M M; Macías, M; Cantero, D

2002-01-01

147

A spectrochemical walk: single-site perturbation within a series of six-coordinate ferrous complexes.  

PubMed

A series of ferrous complexes with the pentadentate ligand 2,6-(bis-(bis-2-pyridyl)methoxymethane)pyridine (PY5) was prepared and examined. PY5 binds ferrous iron in a square-pyramidal geometry, leaving a single coordination site accessible for complexation of a wide range of monodentate exogenous ligands: [Fe(II)(PY5)(X)](n+), X = MeOH, H(2)O, MeCN, pyridine, Cl-, OBz-, N(3)-, MeO-, PhO-, and CN-. The spin-states of these ferrous complexes are extremely sensitive to the nature of the single exogenous ligand; the spectroscopic and structural properties correlate with their high-spin (hs) or low-spin (ls) electronic ground state. Systematic metrical trends within six crystallographic structures clearly indicate a preferred conformational binding mode of the PY5 ligand. The relative binding affinities of the exogenous ligands in MeOH indicate that exogenous ligand charge is the primary determinant of the binding affinity; the [Fe(II)(PY5)](2+) unit preferentially binds anionic ligands over neutral ligands. At parity of charge, strong-field ligands are preferentially bound over weak-field ligands. In MeOH, the pK(a) of the exogenously ligated MeOH in [Fe(PY5)(MeOH)](2+) (9.1) limits the scope of exogenous ligands, as strongly basic ligands preferentially deprotonate [Fe(PY5)(MeOH)](2+) to yield [Fe(PY5)(OMe)](1+) rather than ligate to the ferrous center. Exogenous ligation by a strongly basic ligand, however, can be achieved in polar aprotic solvents. PMID:12206687

Goldsmith, Christian R; Jonas, Robert T; Cole, Adam P; Stack, T Daniel P

2002-09-01

148

Laser beam welding non-ferrous metals. (Latest citations from METADEX). Published Search  

SciTech Connect

The bibliography contains citations concerning techniques and the evaluation of laser beam welding of non-ferrous metals. Welding parameters, such as incident laser power and welding speed, are reviewed in relation to their characterization of weld microstructure. Weld examination techniques are cited, including macrophotography, light and electron microscopy, and microhardness profiling. (Contains a minimum of 170 citations and includes a subject term index and title list.)

Not Available

1994-09-01

149

Advanced Oxidation Protein Products, Ferrous Oxidation in Xylenol Orange, and Malondialdehyde Levels in Thyroid Cancer  

Microsoft Academic Search

Aims and Background  The oxidation of protein plays an essential role in the pathogenesis of an important number of degenerative and cancer diseases,\\u000a which is now widely recognized. The aim is to examine advanced oxidation protein products (AOPPs), lipid peroxidation products\\u000a malondialdehyde (MDA), and ferrous oxidation in xylenol orange (FOX) in blood samples of papillary thyroid cancer patients\\u000a compared with healthy

Funda Kosova; Bahad?r Çetin; Melih Ak?nc?; Sabahattin Aslan; Zeki Ar?; Aylin Sepici; Nilgün Altan; Abdullah Çetin

2007-01-01

150

Operational pH in packed-bed reactors for ferrous ion bio-oxidation  

Microsoft Academic Search

The flooded packed-bed bioreactor plays a major role in the field of applications of ferrous ion bio-oxidation. The pH is an important variable in the control of this type of reactor, upon which the functionality of biofilm depends.In the present work, five continuous flooded packed-bed reactors have been inoculated with mixed cultures (Acidithiobacillus ferrooxidans and Leptospirillum ferooxidans) and fed with

A. Mazuelos; F. Carranza; R. Romero; N. Iglesias; E. Villalobo

2010-01-01

151

Immobilization of Acidithiobacillus ferrooxidans by a PVA–boric acid method for ferrous sulphate oxidation  

Microsoft Academic Search

Acidithiobacillus ferrooxidans was immobilized in poly(vinyl alcohol) (PVA) by a PVA–boric acid method, and spherical beads of uniform size were produced. Biooxidation of ferrous iron by immobilized cells was investigated in repeated batch culture and continuous operation in a laboratory scale packed-bed bioreactor. During repeated batch culture, the cell-immobilized gels were stable and showed high constant iron-oxidizing activity. In continuous

Zhong-er Long; Yunhong Huang; Zhaoling Cai; Wei Cong; Fan Ouyang

2004-01-01

152

Stress corrosion cracking of several high strength ferrous and nickel alloys  

NASA Technical Reports Server (NTRS)

The stress corrosion cracking resistance of several high strength ferrous and nickel base alloys has been determined in a sodium chloride solution. Results indicate that under these test conditions Multiphase MP35N, Unitemp L605, Inconel 718, Carpenter 20Cb and 20Cb-3 are highly resistant to stress corrosion cracking. AISI 410 and 431 stainless steels, 18 Ni maraging steel (250 grade) and AISI 4130 steel are susceptible to stress corrosion cracking under some conditions.

Nelson, E. E.

1971-01-01

153

Plutonium-uranium separation in the Purex process using mixtures of hydroxylamine nitrate and ferrous sulfamate  

Microsoft Academic Search

Laboratory studies, followed by plant operation, established that a mixture of hydroxylamine nitrate (HAN) and ferrous sulfamate (FS) is superior to FS used alone as a reductant for plutonium in the Purex first cycle. FS usage has been reduced by about 70% (from 0.12 to 0.04M) compared to the pre-1978 period. This reduced the volume of neutralized waste due to

J. M. McKibben; D. F. Chostner; E. G. Orebaugh

2010-01-01

154

Characterization of Two Different Five-Coordinate Soluble Guanylate Cyclase Ferrous–Nitrosyl Complexes †  

Microsoft Academic Search

ABSTRACT: Soluble guanylate cyclase (sGC), a hemoprotein, is the primary nitric oxide (NO) receptor in higher eukaryotes. The binding of NO to sGC leads to the formation of a five-coordinate ferrous-nitrosyl complex,and a several hundred-fold increase in cGMP synthesis. NO activation of sGC is influenced by GTP and the allosteric activators YC-1 and BAY 41-2272. Electron paramagnetic resonance (EPR) spectroscopy

Emily R. Derbyshire; Alexander Gunn; Mohammed Ibrahim; Thomas G. Spiro; R. David Britt; Michael A. Marletta

2008-01-01

155

In Situ Chemical Stabilization of Arsenic-Contaminated Soils Using Ferrous Sulfate  

Microsoft Academic Search

In this paper, a probe into the stabilization effects of ferrous sulfate (FeSO4) came from two aspects-stabilization efficiency and leachate content. Fe\\/As molar ratio, arsenic pollution intensity, soil pH, reacted time interval, competitive ions, such as sulfate(SO42-), phosphate(PO43-) and zinc ion(Zn2+), were studied in order to discuss their effects on the stabilization of arsenic. Results show that ,to all different

Huimin Zhao; Huanzhen Zhang; Min Tang; Fei Li

2010-01-01

156

3-hydroxy-2(1H)-pyridinone chelating agents  

DOEpatents

Disclosed is a series of improved chelating agents and the chelates formed from these agents, which are highly effective upon both injection and oral administration. Several of the most effective are of low toxicity. These chelating agents incorporate within their structure 3-hydroxy-2-pyridinone (3,2-HOPO) moieties with a substituted carbamoyl group ortho to the hydroxy group of the hydroxypyridinone ring. The electron-withdrawing carbamoyl group increases the acidity, as well as the chemical stability towards oxidation and reduction, of the hydroxypyridinones. In the metal complexes of the chelating agents, the amide protons form very strong hydrogen bonds with the adjacent HOPO oxygen donor, making these complexes very stable at physiological conditions. The terminal N-substituents provide a certain degree of lipophilicity to the 3,2-HOPO, increasing oral activity.

Raymond, Kenneth (Berkeley, CA); Xu, Jide (Berkeley, CA)

1999-01-01

157

3-hydroxy-2(1H)-pyridinone chelating agents  

DOEpatents

Disclosed is a series of improved chelating agents and the chelates formed from these agents, which are highly effective upon both injection and oral administration. Several of the most effective are of low toxicity. These chelating agents incorporate within their structure 3-hydroxy-2-pyridinone (3,2-HOPO) moieties with a substituted carbamoyl group ortho to the hydroxy group of the hydroxypyridinone ring. The electron-withdrawing carbamoyl group increases the acidity, as well as the chemical stability towards oxidation and reduction, of the hydroxypyridinones. In the metal complexes of the chelating agents, the amide protons form very strong hydrogen bonds with the adjacent HOPO oxygen donor, making these complexes very stable at physiological conditions. The terminal N-substituents provide a certain degree of lipophilicity to the 3,2-HOPO, increasing oral activity. 2 figs.

Raymond, K.; Xu, J.

1999-04-06

158

Metal chelate process to remove pollutants from fluids  

DOEpatents

The present invention relates to improved methods using an organic iron chelate to remove pollutants from fluids, such as flue gas. Specifically, the present invention relates to a process to remove NO[sub x] and optionally SO[sub 2] from a fluid using a metal ion (Fe[sup 2+]) chelate wherein the ligand is a dimercapto compound wherein the --SH groups are attached to adjacent carbon atoms (HS--C--C--SH) or (SH--C--CCSH) and contain a polar functional group so that the ligand of DMC chelate is water soluble. Alternatively, the DMC is covalently attached to a water insoluble substrate such as a polymer or resin, e.g., polystyrene. The chelate is regenerated using electroreduction or a chemical additive. The dimercapto compound bonded to a water insoluble substrate is also useful to lower the concentration or remove hazardous metal ions from an aqueous solution. 26 figures.

Chang, S.G.T.

1994-12-06

159

Metal chelate process to remove pollutants from fluids  

DOEpatents

The present invention relates to improved methods using an organic iron chelate to remove pollutants from fluids, such as flue gas. Specifically, the present invention relates to a process to remove NO.sub.x and optionally SO.sub.2 from a fluid using a metal ion (Fe.sup.2+) chelate wherein the ligand is a dimercapto compound wherein the --SH groups are attached to adjacent carbon atoms (HS--C--C--SH) or (SH--C--CCSH) and contain a polar functional group so that the ligand of DMC chelate is water soluble. Alternatively, the DMC' is covalently attached to a water insoluble substrate such as a polymer or resin, e.g., polystyrene. The chelate is regenerated using electroreduction or a chemical additive. The dimercapto compound bonded to a water insoluble substrate is also useful to lower the concentration or remove hazardous metal ions from an aqueous solution.

Chang, Shih-Ger T. (El Cerrito, CA)

1994-01-01

160

Cell assay using a two-photon-excited europium chelate  

PubMed Central

We report application of two-photon excitation of europium chelates to immunolabeling of epidermal growth factor receptor (EGFR) cell surface proteins on A431 cancer cells. The europium chelates are excited with two photons of infrared light and emit in the visible. Europium chelates are conjugated to antibodies for EGFR. A431 (human epidermoid carcinoma) cells are labeled with this conjugate and imaged using a multiphoton microscope. To minimize signal loss due to the relatively long-lived Eu3+ emission, the multiphoton microscope is used with scanning laser two-photon excitation and non-scanning detection with a CCD. The chelate labels show very little photobleaching (less than 1% during continuous illumination in the microscope for 20 minutes) and low levels of autofluorescence (less than 1% of the signal from labeled cells). The detection limit of the europium label in the cell assay is better than 100 zeptomoles. PMID:21833362

Xiao, Xudong; Haushalter, Jeanne P.; Kotz, Kenneth T.; Faris, Gregory W.

2011-01-01

161

Research paper Simultaneous metal chelate affinity purification and endotoxin  

E-print Network

Research paper Simultaneous metal chelate affinity purification and endotoxin clearance 22 June 2006 Abstract Endotoxins are frequent contaminants of recombinant proteins produced in Escherichia coli. Due to their adverse effects, endotoxins have to be removed from recombinant proteins prior

Lebendiker, Mario

162

EPR Characterisation of the Ferrous Nitrosyl Complex Formed within the Oxygenase Domain of NO Synthase  

PubMed Central

Nitric oxide is produced in mammals by a class of enzymes called NO synthases (NOSs). It plays a central role in cellular signalling but also has deleterious effects, as it leads to the production of reactive oxygen and nitrogen species. NO forms a relatively stable adduct with ferrous haem proteins, which, in the case of NOS, is also a key catalytic intermediate. Despite extensive studies on the ferrous nitrosyl complex of other haem proteins (in particular myoglobin), little characterisation has been performed in the case of NOS. We report here a temperature-dependent EPR study of the ferrous nitrosyl complex of the inducible mammalian NOS and the bacterial NOS-like protein from Bacillus subtilis. The results show that the overall behaviours are similar to those observed for other haem proteins, but with distinct ratios between axial and rhombic forms in the case of the two NOS proteins. The distal environment appears to control the existence of the axial form and the evolution of the rhombic form. PMID:23943262

Santolini, Jerome; Marechal, Amandine; Boussac, Alain; Dorlet, Pierre

2013-01-01

163

Stable intermediate-spin ferrous iron in lower-mantle perovskite  

SciTech Connect

The lower mantle is dominated by a magnesium- and iron-bearing mineral with the perovskite structure. Iron has the ability to adopt different electronic configurations, and transitions in its spin state in the lower mantle can significantly influence mantle properties and dynamics. However, previous studies aimed at understanding these transitions have provided conflicting results. Here we report the results of high-pressure (up to 110 GPa) and high-temperature (up to 1,000 K) experiments aimed at understanding spin transitions of iron in perovskite at lower-mantle conditions. Our Moessbauer and nuclear forward scattering data for two lower-mantle perovskite compositions demonstrate that the transition of ferrous iron from the high-spin to the intermediate-spin state occurs at approximately 30 GPa, and that high temperatures favour the stability of the intermediate-spin state. We therefore infer that ferrous iron adopts the intermediate-spin state throughout the bulk of the lower mantle. Our X-ray data show significant anisotropic compression of lower-mantle perovskite containing intermediate-spin ferrous iron, which correlates strongly with the spin transition. We predict spin-state heterogeneities in the uppermost part of the lower mantle associated with sinking slabs and regions of upwelling. These may affect local properties, including thermal and electrical conductivity, deformation (viscosity) and chemical behaviour, and thereby affect mantle dynamics.

McCammon, C.; Kantor, I.; Narygina, O.; Rouquette, J.; Ponkratz, U.; Sergueev, I.; Mezouar, M.; Prakapenka, V.; Dubrovinsky, L. (Bayreuth); (ESRF); (UC)

2008-11-10

164

LITERATURE REVIEW: REDUCTION OF NP(V) TO NP (IV)-ALTERNATIVES TO FERROUS SULFAMATE  

SciTech Connect

The baseline approach to control of Np oxidation in UREX and PUREX separation processes is the reduction of Np(V) and Np(VI) to Np(IV) using ferrous sulfamate. Use of this reagent results in increased sulfur and iron concentrations in the liquid waste streams from the process. Presence of these two elements, especially sulfur, increases the complexity of the development of wasteforms for immobilizing these effluents. Investigations are underway to identify reductants that eliminate sulfur and iron from the Np reduction process. While there are a variety of chemical reductants that will reduce Np to Np(IV) in nitric acid media, the reaction rates for most are so slow that the reductants are not be feasible for use in an operating plant process. In an attempt to identify additional alternatives to ferrous sulfamate, a literature search and review was performed. Based on the results of the literature review, it is concluded that photochemical and catalytic processes should also be investigated to test the utility of these two approaches. The catalytic process could be investigated for use in conjunction with chemical oxidants to speed the reaction rates for reductants that react slowly, but would otherwise be appropriate replacements for ferrous sulfamate. The photochemical approach, which has received little attention during the past few decades, also shows promise, especially the photocatalytic approach that includes a catalyst, such as Pt supported on SiC, which can be used in tandem with an oxidant, for Np reduction.

Kessinger, G.; Kyser, E.; Almond, P.

2009-09-28

165

Ferrous iron-dependent drug delivery enables controlled and selective release of therapeutic agents in vivo.  

PubMed

The precise targeting of cytotoxic agents to specific cell types or cellular compartments is of significant interest in medicine, with particular relevance for infectious diseases and cancer. Here, we describe a method to exploit aberrant levels of mobile ferrous iron (Fe(II)) for selective drug delivery in vivo. This approach makes use of a 1,2,4-trioxolane moiety, which serves as an Fe(II)-sensitive "trigger," making drug release contingent on Fe(II)-promoted trioxolane fragmentation. We demonstrate in vivo validation of this approach with the Plasmodium berghei model of murine malaria. Malaria parasites produce high concentrations of mobile ferrous iron as a consequence of their catabolism of host hemoglobin in the infected erythrocyte. Using activity-based probes, we successfully demonstrate the Fe(II)-dependent and parasite-selective delivery of a potent dipeptidyl aminopeptidase inhibitor. We find that delivery of the compound in its Fe(II)-targeted form leads to more sustained target inhibition with greatly reduced off-target inhibition of mammalian cathepsins. This selective drug delivery translates into improved efficacy and tolerability. These findings demonstrate the utility of a purely chemical means to achieve selective drug targeting in vivo. This approach may find useful application in parasitic infections and more broadly in any disease state characterized by aberrant production of reactive ferrous iron. PMID:24145449

Deu, Edgar; Chen, Ingrid T; Lauterwasser, Erica M W; Valderramos, Juan; Li, Hao; Edgington, Laura E; Renslo, Adam R; Bogyo, Matthew

2013-11-01

166

Chelation in metal intoxication XVI. Influence of chelating agents on chromate poisoned rats  

SciTech Connect

The ability of selective polyaminocarboxylic acids and common drugs to reduce the body burden of chromium and restore Cr induced biochemical alterations in chromate intoxicated rats was investigated. 1,2 Cychlohexylene dinitrilotetraacetic acid (CDTA) and triethylenetetramine hexacetic acid (TTHA) were more effective than p-aminosalicylic acid (PAS) and isoniazid (INH) in enhancing urinary excretion of Cr, lowering hepatic and blood levels of Cr and restoring inhibited activity of hepatic aldolase. The chromate antidotal property of chelators seem to be related to the combination of nitrogen and oxygen as the electron donating centres.

Tandon, S.K.; Srivastava, L.

1985-01-01

167

Chelated Ruthenium Catalysts for Z-Selective Olefin Metathesis  

PubMed Central

We report the development of ruthenium-based metathesis catalysts with chelating N-heterocyclic carbene (NHC) ligands which catalyze highly Z-selective olefin metathesis. A very simple and convenient synthetic procedure of such a catalyst has been developed. An intramolecular C-H bond activation of the NHC ligand, which is promoted by anion ligand substitution, forms the appropriate chelate for stereo- controlled olefin metathesis. PMID:21563826

Endo, Koji; Grubbs, Robert H.

2011-01-01

168

Structure and energetics of solvated ferrous and ferric ions: Car-Parrinello molecular dynamics in the DFT+U formalism  

E-print Network

We implemented a rotationally-invariant Hubbard U extension to density-functional theory in the Car-Parrinello molecular dynamics framework, with the goal of bringing the accuracy of the DFT+U approach to finite-temperature simulations, especially for liquids or solids containing transition-metal ions. First, we studied the effects on the Hubbard U on the static equilibrium structure of the hexa-aqua ferrous and ferric ions, and the inner-sphere reorganization energy for the electron-transfer reaction between aqueous ferrous and ferric ions. It is found that the reorganization energy is increased, mostly as a result of the Fe-O distance elongation in the hexa-aqua ferrous ion. Second, we performed a first-principles molecular dynamics study of the solvation structure of the two aqueous ferrous and ferric ions. The Hubbard term is found to change the Fe-O radial distribution function for the ferrous ion, while having a negligible effect on the aqueous ferric ion. Moreover, the frequencies of vibrations between Fe and oxygen atoms in the first-solvation shell are shown to be unaffected by the Hubbard corrections for both ferrous and ferric ions.

P. H. -L. Sit; Matteo Cococcioni; Nicola Marzari

2007-01-12

169

Lead chelation to immobilised Symphytum officinale L. (comfrey) root tannins.  

PubMed

Reported correlations between tannin level and metal accumulation within plant tissues suggest that metal-chelating tannins may help plants to tolerate toxic levels of heavy metal contaminants. This paper supports such correlations using a new method that demonstrated the ability of plant tannins to chelate heavy metals, and showed that the relative levels of tannins in tissues were quantitatively related to lead chelation in vitro. Using this in vitro metal chelation method, we showed that immobilised tannins prepared from lateral roots of Symphytum officinale L., that contained high tannin levels, chelated 3.5 times more lead than those from main roots with lower tannin levels. This trend was confirmed using increasing concentrations of tannins from a single root type, and using purified tannins (tannic acid) from Chinese gallnuts. This study presents a new, simple, and reliable method that demonstrates direct lead-tannin chelation. In relation to phytoremediation, it also suggests that plant roots with more 'built-in' tannins may advantageously accumulate more lead. PMID:19477483

Chin, Lily; Leung, David W M; Harry Taylor, H

2009-07-01

170

Modeling ferrous ferric iron chemistry with application to martian surface geochemistry  

NASA Astrophysics Data System (ADS)

The Mars Global Surveyor, Mars Exploration Rover, and Mars Express missions have stimulated considerable thinking about the surficial geochemical evolution of Mars. Among the major recent mission findings are the presence of jarosite (a ferric sulfate salt), which requires formation from an acid-sulfate brine, and the occurrence of hematite and goethite on Mars. Recent ferric iron models have largely focused on 25 °C, which is a major limitation for models exploring the geochemical history of cold bodies such as Mars. Until recently, our work on low-temperature iron-bearing brines involved ferrous but not ferric iron, also obviously a limitation. The objectives of this work were to (1) add ferric iron chemistry to an existing ferrous iron model (FREZCHEM), (2) extend this ferrous/ferric iron geochemical model to lower temperatures (<0 °C), and (3) use the reformulated model to explore ferrous/ferric iron chemistries on Mars. The FREZCHEM model is an equilibrium chemical thermodynamic model parameterized for concentrated electrolyte solutions using the Pitzer approach for the temperature range from <-70 to 25 °C and the pressure range from 1 to 1000 bars. Ferric chloride and sulfate mineral parameterizations were based, in part, on experimental data. Ferric oxide/hydroxide mineral parameterizations were based exclusively on Gibbs free energy and enthalpy data. New iron parameterizations added 23 new ferrous/ferric minerals to the model for this Na-K-Mg-Ca-Fe(II)-Fe(III)-H-Cl-SO 4-NO 3-OH-HCO 3-CO 3-CO 2-O 2-CH 4-H 2O system. The model was used to develop paragenetic sequences for Rio Tinto waters on Earth and a hypothetical Martian brine derived from acid weathering of basaltic minerals. In general, model simulations were in agreement with field evidence on Earth and Mars in predicting precipitation of stable iron minerals such as jarosites, goethite, and hematite. In addition, paragenetic simulations for Mars suggest that other iron minerals such as lepidocrocite, schwertmannite, ferricopiapite, copiapite, and bilinite may also be present on the surface of Mars. Evaporation or freezing of the Martian brine led to similar mineral precipitates. However, in freezing, compared to evaporation, the following key differences were found: (1) magnesium sulfates had higher hydration states; (2) there was greater total aqueous sulfate (SO 4T = SO 4 + HSO 4) removal; and (3) there was a significantly higher aqueous Cl/SO 4T ratio in the residual Na-Mg-Cl brine. Given the similarities of model results to observations, alternating dry/wet and freeze/thaw cycles and brine migration could have played major roles in vug formation, Cl stratification, and hematite concretion formation on Mars.

Marion, Giles M.; Kargel, Jeffrey S.; Catling, David C.

2008-01-01

171

Modeling aqueous ferrous iron chemistry at low temperatures with application to Mars  

USGS Publications Warehouse

Major uncertainties exist with respect to the aqueous geochemical evolution of the Martian surface. Considering the prevailing cryogenic climates and the abundance of salts and iron minerals on Mars, any attempt at comprehensive modeling of Martian aqueous chemistry should include iron chemistry and be valid at low temperatures and high solution concentrations. The objectives of this paper were to (1) estimate ferrous iron Pitzer-equation parameters and iron mineral solubility products at low temperatures (from < 0 ??C to 25 ??C), (2) incorporate these parameters and solubility products into the FREZCHEM model, and (3) use the model to simulate the surficial aqueous geochemical evolution of Mars. Ferrous iron Pitzer-equation parameters were derived in this work or taken from the literature. Six new iron minerals [FeCl2??4H2O, FeCl2??6H2O, FeSO4??H2O, FeSO4??7H2O, FeCO3, and Fe(OH)3] were added to the FREZCHEM model bringing the total solid phases to 56. Agreement between model predictions and experimental data are fair to excellent for the ferrous systems: Fe-Cl, Fe-SO4, Fe-HCO3, H-Fe-Cl, and H-Fe-SO4. We quantified a conceptual model for the aqueous geochemical evolution of the Martian surface. The five stages of the conceptual model are: (1) carbonic acid weathering of primary ferromagnesian minerals to form an initial magnesium-iron-bicarbonate-rich solution; (2) evaporation and precipitation of carbonates, including siderite (FeCO3), with evolution of the brine to a concentrated NaCl solution; (3) ferrous/ferric iron oxidation; (4) either evaporation or freezing of the brine to dryness; and (5) surface acidification. What began as a dilute Mg-Fe-HCO3 dominated leachate representing ferromagnesian weathering evolved into an Earth-like seawater composition dominated by NaCl, and finally into a hypersaline Mg-Na-SO4-Cl brine. Weathering appears to have taken place initially under conditions that allowed solution of ferrous iron [low O2(g)], but later caused oxidation of iron [high O2(g)]. Surface acidification and/or sediment burial can account for the minor amounts of Martian surface carbonates. This model rests on a large number of assumptions and is therefore speculative. Nevertheless, the model is consistent with current understanding concerning surficial salts and minerals based on Martian meteorites, Mars lander data, and remotely-sensed spectral analyses. ?? 2003 Elsevier Ltd.

Marion, G.M.; Catling, D.C.; Kargel, J.S.

2003-01-01

172

Potential of Presep(®) PolyChelate as a chelating resin: comparative study with some aminocarboxylic acid-type resins.  

PubMed

The potential of Presep(®) PolyChelate as a chelating resin was studied in detail. The chelating resin with extraction capacity for Cu of 0.30 mmol L(-1) could quantitatively extract Cd, Co, Cu, Fe, Mo, Ni, Pb, V, and Zn at pH 4 or 5.5; however, only very scant amounts of Na, K, Mg, and Ca were captured at pH levels below 7. The quantitative extraction could be achieved in 100 - 1000 mL of artificial seawater and at a flow rate of 3 - 30 mL min(-1). The performance of Presep(®) PolyChelate was compared to the other aminocarboxylic acid-type chelating resins, including Nobias Chelate-PA1, Chelex 100, Muromac B-1, Lewatit TP 207, and NTA Superflow, under the same conditions. The solid-phase extraction of the nine elements in the certified reference material (ES-L-1, ground water) and a commercially available table salt was also demonstrated. PMID:24212740

Kagaya, Shigehiro; Saeki, Yumi; Morishima, Daiki; Shirota, Riko; Kajiwara, Takehiro; Kato, Toshifumi; Gemmei-Ide, Makoto

2013-01-01

173

The magnesium chelation step in chlorophyll biosynthesis  

SciTech Connect

In photosynthetic organisms, the biogenesis of energy transducing membranes requires the coordinate synthesis of prosthetic groups, proteins, and various lipids. Two of the major prosthetic groups, chlorophyll and heme, share a common biosynthetic pathway that diverges at the point of metal insertion into protoporphyrin IX (Proto). Insertion of iron leads to the formation of hemes, while insertion of magnesium is the first step unique to chlorophyll formation. This project is directed toward identifying the enzyme(s) responsible for magnesium chelation and elucidating the mechanism which regulates the flux of precursors through the branch point enzymes in isolated chloroplasts. Using intact chloroplasts from greening cucumber cotyledons, we have confirmed the ATP requirement for Mg-Proto formation. Use of non-hydrolyzable ATP analogs, uncouplers and ionophores has led to the conclusions that ATP hydrolysis is necessary, but that this hydrolysis is not linked to the requirement for membrane intactness by transmembrane ion gradients or electrical potentials. The enzyme(s) are flexible with respect to the porphyrin substrate specificity, accepting porphyrins with -vinyl, -ethyl, or -H substituents at the 2 and 4 positions. The activity increases approximately four-fold during greening. Possible physiological feedback inhibitors such as heme, protochlorophyllide, and chlorophyllide had no specific effect on the activity. The activity has now been assayed in barely, corn and peas, with the system from peas almost ten-fold more active than the cucumber system. Work is continuing in pea chloroplasts with the development of a continuous assay and investigation of the feasibility of characterizing an active, organelle-free preparation. 6 figs.

Weinstein, J.

1990-11-01

174

Regional siderosis: a new challenge for iron chelation therapy  

PubMed Central

The traditional role of iron chelation therapy has been to reduce body iron burden via chelation of excess metal from organs and fluids and its excretion via biliary-fecal and/or urinary routes. In their present use for hemosiderosis, chelation regimens might not be suitable for treating disorders of iron maldistribution, as those are characterized by toxic islands of siderosis appearing in a background of normal or subnormal iron levels (e.g., sideroblastic anemias, neuro- and cardio-siderosis in Friedreich ataxia- and neurosiderosis in Parkinson's disease). We aimed at clearing local siderosis from aberrant labile metal that promotes oxidative damage, without interfering with essential local functions or with hematological iron-associated properties. For this purpose we introduced a conservative mode of iron chelation of dual activity, one based on scavenging labile metal but also redeploying it to cell acceptors or to physiological transferrin. The “scavenging and redeployment” mode of action was designed both for correcting aberrant iron distribution and also for minimizing/preventing systemic loss of chelated metal. We first examine cell models that recapitulate iron maldistribution and associated dysfunctions identified with Friedreich ataxia and Parkinson's disease and use them to explore the ability of the double-acting agent deferiprone, an orally active chelator, to mediate iron scavenging and redeployment and thereby causing functional improvement. We subsequently evaluate the concept in translational models of disease and finally assess its therapeutic potential in prospective double-blind pilot clinical trials. We claim that any chelator applied to diseases of regional siderosis, cardiac, neuronal or endocrine ought to preserve both systemic and regional iron levels. The proposed deferiprone-based therapy has provided a paradigm for treating regional types of siderosis without affecting hematological parameters and systemic functions. PMID:24427136

Cabantchik, Zvi Ioav; Munnich, Arnold; Youdim, Moussa B.; Devos, David

2013-01-01

175

The role of chelation in the treatment of other metal poisonings.  

PubMed

These proceedings will review the role of chelation in five metals-aluminum, cadmium, chromium, cobalt, and uranium-in order to illustrate various chelation concepts. The process of "chelation" can often be oversimplified, leading to incorrect assumptions and risking patient harm. For chelation to be effective, two critical assumptions must be fulfilled: the presumed "metal toxicity" must correlate with a given body or a particular compartment burden, and reducing this compartmental or the body burden (through chelation) attenuates toxicity. Fulfilling these assumptions requires an established dose-response relationship, a validated, reproducible means of toxicity assessment (clinical, biochemical, or radiographical), and an appropriate assessment mechanisms of body or compartment burden. While a metal might "technically" be capable of chelation (and readily demonstrable in urine or feces), this is an insufficient endpoint. Clinical relevance must be affirmed. Deferoxamine is an accepted chelator for appropriately documented aluminum toxicity. There is a very minimal treatment window in order to address chelation in cadmium toxicity. In acute toxicity, while no definitive chelation benefit is described, succimer (DMSA), diethylenetriaminepentaacetate (DTPA), and potentially ethylenediaminetetraacetic acid (EDTA) have been considered. In chronic toxicity, chelation is unsupported. There is little evidence to suggest that currently available chromium chelators are efficacious. Similarly, scant human evidence exists with which to provide recommendation for cobalt chelation. DTPA has been recommended for cobalt radionuclide chelation, although DMSA, EDTA, and N-acetylcysteine have also been suggested. DTPA is unsupported for uranium chelation. Sodium bicarbonate is currently recommended, although animal evidence is conflicting. PMID:24113858

Smith, Silas W

2013-12-01

176

Highly regioselective hydroformylation with hemispherical chelators.  

PubMed

The hemispherical diphosphites (R,R)- or (S,S)-5,11,17,23-tetra-tert-butyl-25,27-di(OR)-26,28-bis(1,1'-binaphthyl-2,2'-dioxyphosphanyloxy)calix[4]arene (R=OPr, OCH(2)Ph, OCH(2)-naphtyl, O-fluorenyl; R=H, R'=OPr) (L(R)), all with C(2) symmetry, have been synthesised starting from the appropriate di-O-alkylated calix[4]arene precursor. In the presence of [Rh(acac)(CO)(2)], these ligands straightforwardly provide chelate complexes in which the metal centre sits in a molecular pocket defined by two naphthyl planes related by the C(2) axis and the two apically situated R groups. Hydroformylation of octene with the L(Pr)/Rh system turned out to be highly regioselective, the linear-to-branched (l:b) aldehyde ratio reaching 58:1. The l:b ratio significantly increased when the propyl groups were replaced by -CH(2)Ph (l:b=80) or -CH(2)naphthyl (l:b=100) groups, that is, with substituents able to sterically interact with the apical metal sites, but without inducing an opening of the cleft nesting the catalytic centre. The trend to preferentially form the aldehyde the shape of which fits with the shape of the catalytic pocket was further confirmed in the hydroformylation of styrene, for which, in contrast to catalysis with conventional diphosphanes, the linear aldehyde was the major product (up to ca. 75 % linear aldehyde). In the hydroformylation of trans-2-octene with the L(benzyl)/Rh system, combined isomerisation/hydroformylation led to a remarkably high l:b aldehyde ratios of 25, thus showing that isomerisation is more effective than hydroformylation. Unusually large amounts of linear products were also observed with all the above diphosphites in the tandem hydroformylation/amination of styrene (l:b of ca. 3:1) as well as in the hydroformylation of allyl benzyl ether (l:b ratio up to 20). PMID:18686280

Sémeril, David; Matt, Dominique; Toupet, Loïc

2008-01-01

177

3-hydroxy-2(1H)-pyridinone chelating agents  

DOEpatents

Disclosed is a series of improved metal chelating agents, which are highly effective upon both injection and oral administration; several of the most effective are of low toxicity. These chelating agents incorporate within their structure 1-hydroxy-2-pyridinone (1,2-HOPO) and 3-hydroxy-2-pyridinone (3,2-HOPO) moieties with a substituted carbamoyl group ortho to the hydroxy or oxo groups of the hydroxypyridinone ring. The electron-withdrawing carbamoyl group increases the acidity of the hydroxypyridinones. In the metal complexes of the chelating agents, the amide protons form very strong hydrogen bonds with its adjacent HOPO oxygen donor, making these complexes very stable at physiological conditions. The terminal N-substituents provides a certain degree of lipophilicity to the 3,2-HOPO, increasing oral activity. Also disclosed is a method of making the chelating agents and a method of producing a known compound, 3-hydroxy-1-alkyl-2(1H)pyridinone, used as a precursor to the chelating agent, safely and in large quantities. 2 figs.

Raymond, K.N.; Xu, J.

1997-04-29

178

3-hydroxy-2(1H)-pyridinone chelating agents  

DOEpatents

Disclosed is a series of improved metal chelating agents, which are highly effective upon both injection and oral administration; several of the most effective are of low toxicity. These chelating agents incorporate within their structure 1-hydroxy-2-pyridinone (1,2-HOPO) and 3-hydroxy-2-pyridinone (3,2-HOPO) moieties with a substituted carbamoyl group ortho to the hydroxy or oxo groups of the hydroxypyridinone ring. The electron-withdrawing carbamoyl group increases the acidity of the hydroxypyridinones. In the metal complexes of said chelating agents, the amide protons form very strong hydrogen bonds with its adjacent HOPO oxygen donor, making these complexes very stable at physiological conditions. The terminal N-substituents provides a certain degree of lipophilicity to said 3,2-HOPO, increasing oral activity. Also disclosed is a method of making the chelating agents and a method of producing a known compound, 3-hydroxy-1-alkyl-2(1H)pyridinone, used as a precursor to the chelating agent, safely and in large quantities.

Raymond, Kenneth N. (Berkeley, CA); Xu, Jide (Berkeley, CA)

1997-01-01

179

Elucidating the Role of Ferrous Ion Cocatalyst in Enhancing Dilute Acid Pretreatment of Lignocellulosic Biomass  

SciTech Connect

Recently developed iron cocatalyst enhancement of dilute acid pretreatment of biomass is a promising approach for enhancing sugar release from recalcitrant lignocellulosic biomass. However, very little is known about the underlying mechanisms of this enhancement. In the current study, our aim was to identify several essential factors that contribute to ferrous ion-enhanced efficiency during dilute acid pretreatment of biomass and to initiate the investigation of the mechanisms that result in this enhancement. During dilute acid and ferrous ion cocatalyst pretreatments, we observed concomitant increases in solubilized sugars in the hydrolysate and reducing sugars in the (insoluble) biomass residues. We also observed enhancements in sugar release during subsequent enzymatic saccharification of iron cocatalyst-pretreated biomass. Fourier transform Raman spectroscopy showed that major peaks representing the C-O-C and C-H bonds in cellulose are significantly attenuated by iron cocatalyst pretreatment. Imaging using Prussian blue staining indicated that Fe{sup 2+} ions associate with both cellulose/xylan and lignin in untreated as well as dilute acid/Fe{sup 2+} ion-pretreated corn stover samples. Analyses by scanning electron microscopy and transmission electron microscopy revealed structural details of biomass after dilute acid/Fe{sup 2+} ion pretreatment, in which delamination and fibrillation of the cell wall were observed. By using this multimodal approach, we have revealed that (1) acid-ferrous ion-assisted pretreatment increases solubilization and enzymatic digestion of both cellulose and xylan to monomers and (2) this pretreatment likely targets multiple chemistries in plant cell wall polymer networks, including those represented by the C-O-C and C-H bonds in cellulose.

Wei, H.; Donohoe, B. S.; Vinzant, T. B.; Ciesielski, P. N.; Wang, W.; Gedvilas, L. M.; Zeng, Y.; Johnson, D. K.; Ding, S. Y.; Himmel, M. E.; Tucker, M. P.

2011-01-01

180

Characterization of a Ferrous Iron-Responsive Two-Component System in Nontypeable Haemophilus influenzae  

PubMed Central

Nontypeable Haemophilus influenzae (NTHI), an opportunistic pathogen that is commonly found in the human upper respiratory tract, has only four identified two-component signal transduction systems. One of these, an ortholog to the QseBC (quorum-sensing Escherichia coli) system, was characterized. This system, designated firRS, was found to be transcribed in an operon with a gene encoding a small, predicted periplasmic protein with an unknown function, ygiW. The ygiW-firRS operon exhibited a unique feature with an attenuator present between ygiW and firR that caused the ygiW transcript level to be 6-fold higher than the ygiW-firRS transcript level. FirRS induced expression of ygiW and firR, demonstrating that FirR is an autoactivator. Unlike the QseBC system of E. coli, FirRS does not respond to epinephrine or norepinephrine. FirRS signal transduction was stimulated when NTHI cultures were exposed to ferrous iron or zinc but was unresponsive to ferric iron. Notably, the ferrous iron-responsive activation only occurred when a putative iron-binding site in FirS and the key phosphorylation aspartate in FirR were intact. FirRS was also activated when cultures were exposed to cold shock. Mutants in ygiW, firR, and firS were attenuated during pulmonary infection, but not otitis media. These data demonstrate that the H. influenzae strain 2019 FirRS is a two-component regulatory system that senses ferrous iron and autoregulates its own operon. PMID:22961857

Steele, Kendra H.; O'Connor, Lauren H.; Burpo, Nicole; Kohler, Katharina

2012-01-01

181

Elucidating the role of ferrous ion cocatalyst in enhancing dilute acid pretreatment of lignocellulosic biomass  

PubMed Central

Background Recently developed iron cocatalyst enhancement of dilute acid pretreatment of biomass is a promising approach for enhancing sugar release from recalcitrant lignocellulosic biomass. However, very little is known about the underlying mechanisms of this enhancement. In the current study, our aim was to identify several essential factors that contribute to ferrous ion-enhanced efficiency during dilute acid pretreatment of biomass and to initiate the investigation of the mechanisms that result in this enhancement. Results During dilute acid and ferrous ion cocatalyst pretreatments, we observed concomitant increases in solubilized sugars in the hydrolysate and reducing sugars in the (insoluble) biomass residues. We also observed enhancements in sugar release during subsequent enzymatic saccharification of iron cocatalyst-pretreated biomass. Fourier transform Raman spectroscopy showed that major peaks representing the C-O-C and C-H bonds in cellulose are significantly attenuated by iron cocatalyst pretreatment. Imaging using Prussian blue staining indicated that Fe2+ ions associate with both cellulose/xylan and lignin in untreated as well as dilute acid/Fe2+ ion-pretreated corn stover samples. Analyses by scanning electron microscopy and transmission electron microscopy revealed structural details of biomass after dilute acid/Fe2+ ion pretreatment, in which delamination and fibrillation of the cell wall were observed. Conclusions By using this multimodal approach, we have revealed that (1) acid-ferrous ion-assisted pretreatment increases solubilization and enzymatic digestion of both cellulose and xylan to monomers and (2) this pretreatment likely targets multiple chemistries in plant cell wall polymer networks, including those represented by the C-O-C and C-H bonds in cellulose. PMID:22074910

2011-01-01

182

Clean Ferrous Casting Technology Research. Annual report, September 29, 1993--September 28, 1994  

SciTech Connect

This annual report covers work performed in the first year of research on Clean Ferrous Casting Technology Research. During this year the causes of penetration of cast iron in sand molds were defined and a program which predicts the occurrence of penetration was written and verified in commercial foundries. Calculations were made to size a reaction chamber to remove inclusions from liquid steel using electromagnetic force and the chamber was built. Finally, significant progress was made in establishing pouring practices which avoid re-oxidation of steel during pouring application of revised pouring practices have led to reduced inclusion levels in commercially poured steel castings.

Stefanescu, D.M.; Lane, A.M.; Giese, S.R.; Pattabhi, R.; El-Kaddah, N.H.; Griffin, J.; Bates, C.E.; Piwonka, T.S.

1994-10-01

183

Friction and surface chemistry of some ferrous-base metallic glasses  

NASA Technical Reports Server (NTRS)

The friction properties of some ferrous-base metallic glasses were measured both in argon and in vacuum to a temperature of 350 C. The alloy surfaces were also analyzed with X-ray photoelectron spectroscopy to identify the compounds and elements present on the surface. The results of the investigation indicate that even when the surfaces of the amorphous alloys, or metallic glasses, are atomically clean, bulk contaminants such as boric oxide and silicon dioxide diffuse to the surfaces. Friction measurements in both argon and vacuum indicate that the alloys exhibit higher coefficients of friction in the crystalline state than they do in the amorphous state.

Miyoshi, K.; Buckley, D. H.

1982-01-01

184

Characterization of Jarosite Formed upon Bacterial Oxidation of Ferrous Sulfate in a Packed-Bed Reactor †  

PubMed Central

A packed-bed bioreactor with activated-carbon particles as a carrier matrix material inoculated with Thiobacillus ferrooxidans was operated at a pH of 1.35 to 1.5 to convert ferrous sulfate to ferric sulfate. Despite the low operating pH, trace amounts of precipitates were produced in both the reactor and the oxidized effluent. X-ray diffraction and chemical analyses indicated that the precipitates were well-ordered potassium jarosite. The chemical analyses also revealed a relative deficiency of Fe and an excess of S in the reactor sample compared with the theoretical composition of potassium jarosite. Images PMID:16347799

Grishin, Sergei I.; Bigham, Jerry M.; Tuovinen, Olli H.

1988-01-01

185

Hydrocracking with molten zinc chloride catalyst containing 2-12% ferrous chloride  

DOEpatents

In a process for hydrocracking heavy aromatic polynuclear carbonaceous feedstocks to produce hydrocarbon fuels boiling below about 475.degree. C. by contacting the feedstocks with hydrogen in the presence of a molten zinc chloride catalyst and thereafter separating at least a major portion of the hydrocarbon fuels from the spent molten zinc chloride catalyst, an improvement comprising: adjusting the FeCl.sub.2 content of the molten zinc chloride to from about 2 to about 12 mol percent based on the mixture of ferrous chloride and molten zinc chloride.

Zielke, Clyde W. (McMurray, PA); Bagshaw, Gary H. (Library, PA)

1981-01-01

186

Stabilization/solidification of waste ferrous sulphate from titanium dioxide production by fluidized bed combustion product.  

PubMed

A treatment procedure to allow the disposal of waste ferrous sulphate was developed. This waste contains sulphuric acid and originates from titanium dioxide production. The process is based on simultaneous neutralization and stabilization/solidification (S/S) of the waste by means of fluidized bed combustion product (FBC-P). The prepared stabilized waste specimens have a solid matrix and their batch leachates display practically neutral pH and also satisfactory conductivity values. The leachate composition is notable in its absence of toxic metals and even iron. PMID:11150128

Vondruska, M; Bednarik, V; Sild, M

2001-01-01

187

Iron chelation inhibits the development of pulmonary vascular remodeling  

PubMed Central

Reactive oxygen species (ROS) have been implicated in the pathogenesis of pulmonary hypertension. Since iron is an important regulator of ROS biology, the present study examined the effect of iron chelation on the development of pulmonary vascular remodeling. The administration of an iron chelator, deferoxamine, to rats prevented chronic hypoxia-induced pulmonary hypertension and pulmonary vascular remodeling. Various iron chelators inhibited growth of cultured pulmonary artery smooth muscle cells. Protein carbonylation, an important iron-dependent biological event, was promoted in association with pulmonary vascular remodeling and cell growth. A proteomic approach identified that Rho GDP-dissociation inhibitor (a negative regulator of RhoA) is carbonylated. In human plasma, the protein carbonyl content was significantly higher in patients with idiopathic pulmonary arterial hypertension than in healthy controls. These results suggest that iron plays an important role in the ROS-dependent mechanism underlying the development of pulmonary hypertension. PMID:22974762

Wong, Chi-Ming; Preston, Ioana R.; Hill, Nicholas S.; Suzuki, Yuichiro J.

2012-01-01

188

Inositol hexaphosphate: a potential chelating agent for uranium.  

PubMed

Chelation therapy is an optimal method to reduce the radionuclide-related risks. In the case of uranium incorporation, the treatment of choice is so far i.v infusion of a 1.4% sodium bicarbonate solution, but the efficacy has been proved to be not very high. In this study, we examine the efficacy of some substances: bicarbonate, citrate, diethylenetriamine pentaacetic acid (DTPA), ethidronate (EHBP) and inositol hexaphosphate (phytic acid) to chelate uranium using a test developed by Braun et al. Different concentrations of phytic acid, an abundant component of plant seeds that is widely distributed in animal cells and tissues in substantial levels, were tested and compared to the same concentrations of sodium citrate, bicarbonate, EHBP and DTPA. The results showed a strong affinity of inositol hexaphosphate for uranium, suggesting that it could be an effective chelating agent for uranium in vivo. PMID:17627956

Cebrian, D; Tapia, A; Real, A; Morcillo, M A

2007-01-01

189

Molecular nanotechnologies of gelatin-immobilization using macrocyclic metal chelates  

PubMed Central

This article is a review of recent developments in the self-assembled nanostructures based on chelate coordination compounds. Molecular nanotechnologies of self-assembly of 3d-element aza- and thiazametalmacrocyclic complexes that happen in nanoreactors on the basis of metal hexacyanoferrate(II) gelatin-immobilized matrix under their contact with water solutions containing various (N,O,S)-donor atomic ligands and organic compounds having one or two carbonyl groups have been considered in this review. It has been noted that the assortment of macrocyclic metal chelates obtained as a result of using molecular nanotechnologies in such specific conditions considerably differs from the assortment of metal chelates formed at the conditions traditional for chemical synthesis. PMID:24516711

Mikhailov, Oleg V.

2014-01-01

190

Aluminium leaching using chelating agents as compositions of food.  

PubMed

In this work, we study aluminium (Al) leaching using three chelating agents (lactic acid, oxalic acid, and citric acid) that are commonly found in foods and beverages. We test acids, sodium, potassium and lithium salts of these three chelating agents. Aluminium concentrations are determined by using Graphite Furnace Atomic Absorption Spectrometry (GFAAS) after a one hour incubation of the aluminium with the chelating agent. We study three concentrations corresponding to the lower, median, and to the higher levels of these substances that are commonly found in consumable foods. We select ambient and boiling temperatures for the incubation. We found that at ambient temperature, the variation of Al leaching depends on the chemical form. Al leaching is significantly higher at 100 degrees C than at the ambient temperature. The salty form for the composition releases more Al than the acidic form. PMID:17434655

Karbouj, Rim

2007-09-01

191

Conformational and spectroscopic investigation of 3-hydroxyflavone-aluminium chelates  

NASA Astrophysics Data System (ADS)

3-Hydroxyflavone (3HF), which is the simplest molecule of the flavonol class, possesses chelating properties towards Al(III). Spectrophotometric methods have shown that the 3HF molecule forms an Al(3HF) 2 complex in pure methanol. The structure of this complex, obtained by quantum semi-empirical AM1 method, indicated that complexed 3HF adopts a pyronium form. Structural and electronic modifications induced by chelation are illustrated by the important frequency shifts observed between free and complexed 3HF FT-Raman spectra and by the chemical shifts variations in the 13C NMR spectra of the two species. Complexes with the same stoichiometry were formed when AcO - or MeO - are present in the medium. However, in acidic medium the chelate composition is Al 2(3HF).

Boudet, Anne-Charlotte; Cornard, Jean-Paul; Merlin, Jean-Claude

2000-03-01

192

Ferrous Analysis.  

ERIC Educational Resources Information Center

Elements covered in this review include: aluminum, antimony, arsenic, bismuth, boron, calcium, carbon, chromium, cobalt, copper, hydrogen, iron, lead, magnesium, manganese, molybdenum, nickel, niobium, nitrogen, oxygen, phosphorus, platinum, rare earths, silicons, sulfur, tin, titanium, tungsten, vanadium, zinc, and zirconium. Analytical methods…

Straub, William A.

1989-01-01

193

Heavy metal displacement in chelate-irrigated soil during phytoremediation  

NASA Astrophysics Data System (ADS)

Heavy metals in wastewater sewage sludge (biosolids), applied to land, contaminate soils. Phytoremediation, the use of plants to clean up toxic heavy metals, might remove them. Chelating agents are added to soil to solubilize the metals for enhanced phytoextraction. Yet no studies follow the displacement and leaching of heavy metals in soil with and without roots following solubilization with chelates. The objective of this work was to determine the mobility of heavy metals in biosolids applied to the surface of soil columns (76 cm long; 17 cm diam.) with or without plants (barley; Hordeum vulgare L.). Three weeks after barley was planted, all columns were irrigated with the disodium salt of the chelating agent, EDTA (ethylenediamine tetraacetic acid) (0.5 g/kg soil). Drainage water, soil, and plants were analyzed for heavy metals (Cd, Cu, Fe, Mn, Ni, Pb, Zn). Total concentrations of the heavy metals in all columns at the end of the experiment generally were lower in the top 30 cm of soil with EDTA than without EDTA. The chelate increased concentrations of heavy metals in shoots. With or without plants, the EDTA mobilized Cd, Fe, Mn, Ni, Pb, and Zn, which leached to drainage water. Drainage water from columns without EDTA had concentrations of these heavy metals below detection limits. Only Cu did not leach in the presence of EDTA. Even though roots retarded the movement of Cd, Fe, Mn, Ni, Pb, and Zn through the EDTA-treated soil from 1 d (Cd) to 5 d (Fe), the drainage water from columns with EDTA had concentrations of Cd, Fe, Mn, and Pb that exceeded drinking water standards by 1.3, 500, 620, and 8.6 times, respectively. Because the chelate rendered Cd, Fe, Mn, Ni, Pb, and Zn mobile, it is suggested that the theory for leaching of soluble salts, put forward by Nielsen and associates in 1965, could be applied to control movement of the heavy metals for maximum uptake during chelate-assisted phytoremediation.

Madrid, F.; Liphadzi, M. S.; Kirkham, M. B.

2003-03-01

194

Combinational chelation therapy abrogates lead-induced neurodegeneration in rats  

SciTech Connect

Lead, a ubiquitous and potent neurotoxicant causes oxidative stress which leads to numerous neurobehavioral and physiological alterations. The ability of lead to bind sulfhydryl groups or compete with calcium could be one of the reasons for its debilitating effects. In the present study, we addressed: i) if chelation therapy could circumvent the altered oxidative stress and prevent neuronal apoptosis in chronic lead-intoxicated rats, ii) whether chelation therapy could reverse biochemical and behavioral changes, and iii) if mono or combinational therapy with captopril (an antioxidant) and thiol chelating agents (DMSA/MiADMSA) is more effective than individual thiol chelator in lead-exposed rats. Results indicated that lead caused a significant increase in reactive oxygen species, nitric oxide, and intracellular free calcium levels along with altered behavioral abnormalities in locomotor activity, exploratory behavior, learning, and memory that were supported by changes in neurotransmitter levels. A fall in membrane potential, release of cytochrome c, and DNA damage indicated mitochondrial-dependent apoptosis. Most of these alterations showed significant recovery following combined therapy with captopril with MiADMSA and to a smaller extend with captopril + DMSA over monotherapy with these chelators. It could be concluded from our present results that co-administration of a potent antioxidant (like captopril) might be a better treatment protocol than monotherapy to counter lead-induced oxidative stress. The major highlight of the work is an interesting experimental evidence of the efficacy of combinational therapy using an antioxidant with a thiol chelator in reversing neurological dystrophy caused due to chronic lead exposure in rats.

Pachauri, Vidhu; Saxena, Geetu; Mehta, Ashish; Mishra, Deepshikha [Division of Pharmacology and Toxicology, Defence Research and Development Establishment, Jhansi Road, Gwalior-474 001 (India); Flora, Swaran J.S. [Division of Pharmacology and Toxicology, Defence Research and Development Establishment, Jhansi Road, Gwalior-474 001 (India)], E-mail: sjsflora@hotmail.com

2009-10-15

195

Iron chelating strategies in systemic metal overload, neurodegeneration and cancer.  

PubMed

Iron is a trace element required for normal performance of cellular processes. Because both the deficiency and excess of this metal are dangerous, its absorption, distribution and accumulation must be tightly regulated. Disturbances of iron homeostasis and an increase in its level may lead to overload and neurodegenerative diseases. Phlebotomy was for a long time the only way of removing excess iron. But since there are many possible disadvantages of this method, chelation therapy seems to be a logical approach to remove toxic levels of iron. In clinical use, there are three drugs: desferrioxamine, deferiprone and deferasirox. FBS0701, a novel oral iron chelator, is under clinical trials with very promising results. Developing novel iron-binding chelators is an urgent matter, not only for systemic iron overload, but also for neurodegenerative disorders, such as Parkinson's disease. Deferiprone is also used in clinical trials in Parkinson's disease. In neurodegenerative disorders the main goal is not only to remove iron from brain tissues, but also its redistribution in system. Few chelators are tested for their potential use in neurodegeneration, such as nonhalogeneted derivatives of clioquinol. Such compounds gave promising results in animal models of neurodegenerative diseases. Drugs of possible use in neurodegeneration must meet certain criteria. Their development includes the improvement in blood brain barrier permeability, low toxicity and the ability to prevent lipid peroxidation. One of the compounds satisfying these requirements is VK28. In rat models it was able to protect neurons in very low doses without significantly changing the iron level in liver or serum. Also iron chelators able to regulate activity of monoamine oxidase were tested. Polyphenols and flavonoids are able to prevent lipid peroxidation and demonstrate neuroprotective activity. While cancer does not involve true iron overload, neoplastic cells have a higher iron requirement and are especially prone to its depletion. It was shown, that desferrioxamine and deferasirox are antiproliferative agents active in several types of cancer. Very potent compounds with possible use as anticancer drugs are thiosemicarbazones. They are able to inhibit ribonucleotide reductase, an enzyme involved in DNA synthesis. Because the relationship between the development of overload / neurodegenerative disorders, or cancer, and iron are very complex, comprehension of the mechanisms involved in the regulation of iron homeostasis is a crucial factor in the development of new pharmacological strategies based on iron chelation. In view of various factors closely involved in pathogenesis of such diseases, designing multifunctional metal-chelators seems to be the most promising approach, but it requires a lot of effort. In this perspective, the review summarizes systemic iron homeostasis, and in brain and cancer cells, iron dysregulation in neurodegenerative disease and possible chelation strategies in the treatment of metal systemic overload, neurodegeneration and cancer. PMID:25005181

Gumienna-Kontecka, Elzbieta; Pyrkosz-Bulska, Monika; Szebesczyk, Agnieszka; Ostrowska, Malgorzata

2014-01-01

196

Removal of phenol from saline water by polyamine chelating resin.  

PubMed

Removal of phenol from saline water was carried out with chelating resin. A polyamine chelating resin, Diaion CR-20, removed phenol compounds selectively from industrial wastewater containing 2% salt. From saline water containing 20 mg/L phenol, 70% of the phenol was removed. After treatment, phenol was eluted from the resin by aqueous NaOH, and the resin could also be regenerated by heating in air. Diaion CR-20 adsorbed phenol even in the presence of FeCl3, indicating that treatment with this resin of wastewater containing metal can remove phenol and metal cations in a single step. PMID:24185065

Yamada, Arisa; Matsui, Akihiro; Tsuji, Hideyuki

2013-01-01

197

Gas and liquid chromatography of metal chelates of pentamethylene dithiocarbamate  

Microsoft Academic Search

Capillary GC and HPLC of metal chelates of pentamethylene dithiocarbamate were examined. Copper(II), nickel(II), cobalt(III), iron(III), manganese(II) and chromium(III) chelates formed in slightly acidic media (pH 5) were extracted in methyl isobutyl ketone or chloroform. Capillary GC elution and separation was carried out on methylsilicone DB-1 column (25 m×0.2 mm I.D.) with film thickness 0.25 ?m. Electron-capture detection was used.

M. A Arain; M. Y Khuhawar; M. I Bhanger

2002-01-01

198

Studies with Ferrous Sulfamate and Alternate Reductants for 2nd Uranium Cycle  

SciTech Connect

A wide range of miniature mixer-settler tests were conducted to determine the source of iron and sulfur contamination in the uranium product stream (''1EU'') of H Canyon's 2nd Uranium Cycle. The problem was reproduced on the laboratory scale mixer-settlers by changing the feed location of ferrous sulfamate from stage D4 to stage D1. Other process variables effected no change. It was later determined that ferrous sulfamate (FS) solids had plugged the FS line to stage D4, causing FS to backup a ventline and enter the Canyon process at stage D1. Pluggage was almost certainly due to precipitation of FS solids during extended process downtime. During the search for the root cause, tests showed that FS solids were quite small (1-10 mm), and a portion of them could bypass the current Canyon prefilter (3-mm). Also, additional tests were done to find an alternate means of reducing and thereby removing plutonium and neptunium from the uranium product. These tests showed that FS was a more effective reductant than either ascorbic acid or a hydroxylamine nitrate (HAN) / dilute FS combination.

Crowder, M.L.

2003-01-15

199

Effects of ferrous and manganese ions on anammox process in sequencing batch biofilm reactors.  

PubMed

Ferrous and manganese ions, as essential elements, significantly affect the synthesis of Haem-C, which participates in the energy metabolism and proliferation of anammox bacteria. In this study, two identical sequencing batch biofilm reactors were used to investigate the effects of ferrous and manganese ions on nitrogen removal efficiency and the potential of metal ions serving as electron donor/acceptors in the anammox process. Fluorescence in situ hybridization analysis was applied to investigate the microbial growth. Results showed that the nitrogen removal increased at high concentrations of Fe(2+) and Mn(2+) and the maximum removal efficiency was nearly 95% at Fe(2+) 0.08 mmol/L and Mn(2+) 0.05 mmol/L, which is nearly 15% and 8% higher than at the lowest Fe(2+) and Mn(2+) concentrations (0.04 and 0.0125 mmol/L). The stabilities of the anammox reactor and the anammox bacterial growth were also enhanced with the elevated Fe(2+) and Mn(2+) concentrations. The Fe(2+) and Mn(2+) were consumed by anammox bacteria along with the removal of ammonia and nitrite. Stoichiometry analysis showed Fe(2+) could serve as an electron donor for NO(-)3-N in the anammox process. Nitrate could be reduced with Fe(2+) serving as the electron donor in the anammox system, which causes the value of NO(-)2-N/NH(-)4-N to decrease with the increasing of N-removal efficiency. PMID:25079633

Huang, Xiaoli; Gao, Dawen; Peng, Sha; Tao, Yu

2014-05-01

200

Olfactory ferric and ferrous iron absorption in iron-deficient rats  

PubMed Central

The absorption of metals from the nasal cavity to the blood and the brain initiates an important route of occupational exposures leading to health risks. Divalent metal transporter-1 (DMT1) plays a significant role in the absorption of intranasally instilled manganese, but whether iron uptake would be mediated by the same pathway is unknown. In iron-deficient rats, blood 59Fe levels after intranasal administration of the radioisotope in the ferrous form were significantly higher than those observed for iron-sufficient control rats. Similar results were obtained when ferric iron was instilled intranasally, and blood levels of 59Fe were even greater in the iron-deficient rats compared with the amount of ferrous iron absorbed. Experiments with Belgrade (b/b) rats showed that DMT1 deficiency limited ferric iron uptake from the nasal cavity to the blood compared with +/b controls matched for iron deficiency. These results indicate that olfactory uptake of ferric iron by iron-deficient rats involves DMT1. Western blot experiments confirmed that DMT1 levels are significantly higher in iron-deficient rats compared with iron-sufficient controls in olfactory tissue. Thus the molecular mechanism of olfactory iron absorption is regulated by body iron status and involves DMT1. PMID:22492739

Ruvin Kumara, V. M.

2012-01-01

201

Expression, purification and functional reconstitution of FeoB, the ferrous iron transporter from Pseudomonas aeruginosa.  

PubMed

The FeoB Fe(II) transporter from the drug resistant pathogen, Pseudomonas aeruginosa is essential for ferrous iron transport and is implicated in virulence and biofilm development. Hence it is an attractive target for the development of new anti-infective drugs. FeoB is an intriguing protein that consists of a cytosolic N-terminal GTPase domain and an integral membrane domain which most likely acts as ferrous iron permease. Characterisation of FeoB is critical for developing therapeutics aimed at inhibiting this protein. However, structural and functional analysis of FeoB is hampered by the lack of high yield homogenously pure protein which is monodisperse, stable and active in solution. Here we describe the optimised procedure for the recombinant expression of FeoB from P. aeruginosa and provide an evaluation of the most favourable purification, pH and detergent conditions. The functional reconstitution of FeoB in liposomes is also described. This represents the first detailed procedure for obtaining a pure, active and stable FeoB solution in milligram quantities which would be amenable to biochemical, biophysical and structural studies. PMID:24993789

Seyedmohammad, Saeed; Born, Diana; Venter, Henrietta

2014-09-01

202

Degradation kinetics of TNT in the presence of six mineral surfaces and ferrous iron.  

PubMed

Trinitrotoluene (TNT), a nitroaromatic explosive, is a commonly encountered groundwater contaminant in the United States that can pose a human health risk, even at very low aqueous concentrations. This study describes the process characteristics of abiotic degradation of dissolved TNT in the presence of ferrous iron (Fe2+) and six different minerals-processes relevant to a more complete understanding of reduced iron technologies in TNT cleanup. Kinetic degradation batch reactions involving combinations of TNT, ferrous iron, six minerals with varying cation exchange capacity, and two pH buffers were performed. The rate of TNT degradation was quantified using high performance liquid chromatography (HPLC). Unbuffered reactions between TNT, Fe2+, and magnetite, pyrite, quartz, and goethite/quartz were insignificant. However, unbuffered reactions between TNT, Fe2+, and calcite and siderite proceeded rapidly to completion. The difference in reaction rates was attributable to the elevated pH in the presence of the latter minerals. For reactions performed in buffered systems with pH 7.4, degradation followed a second-order kinetics rate law. For reactions in buffered systems with pH 9.0, the reactions proceeded to completion almost instantaneously. The presence of the mineral solid surface was necessary for TNT reduction to proceed, with the most rapid reaction rates occurring in the presence of a suspected hydroxy solid phase that formed at high pH. PMID:15961226

Nefso, E K; Burns, S E; McGrath, C J

2005-08-31

203

Selective Inhibition of the Oxidation of Ferrous Iron or Sulfur in Thiobacillus ferrooxidans  

PubMed Central

The oxidation of either ferrous iron or sulfur by Thiobacillus ferrooxidans was selectively inhibited or controlled by various anions, inhibitors, and osmotic pressure. Iron oxidation was more sensitive than sulfur oxidation to inhibition by chloride, phosphate, and nitrate at low concentrations (below 0.1 M) and also to inhibition by azide and cyanide. Sulfur oxidation was more sensitive than iron oxidation to the inhibitory effect of high osmotic pressure. These differences were evident not only between iron oxidation by iron-grown cells and sulfur oxidation by sulfur-grown cells but also between the iron and sulfur oxidation activities of the same iron-grown cells. Growth experiments with ferrous iron or sulfur as an oxidizable substrate confirmed the higher sensitivity of iron oxidation to inhibition by phosphate, chloride, azide, and cyanide. Sulfur oxidation was actually stimulated by 50 mM phosphate or chloride. Leaching of Fe and Zn from pyrite (FeS2) and sphalerite (ZnS) by T. ferrooxidans was differentially affected by phosphate and chloride, which inhibited the solubilization of Fe without significantly affecting the solubilization of Zn. PMID:10698768

Harahuc, Lesia; Lizama, Hector M.; Suzuki, Isamu

2000-01-01

204

The photochemical origins of life and photoreaction of ferrous ion in the archaean oceans  

NASA Technical Reports Server (NTRS)

A general argument is made for the photochemical origins of life. A constant flux of free energy is required to maintain the organized state of matter called life. Solar photons are the unique source of the large amounts of energy probably required to initiate this organization and certainly required for the evolution of life to occur. The completion of this argument will require the experimental determination of suitable photochemical reactions. It is shown that biogenetic porphyrins readily photooxidize substrates and emit hydrogen in the presence of a catalyst. These results are consistent with the Granick hypothesis, which relates a biosynthetic pathway to its evolutionary origin. It has been shown that photoexcitation of ferrous ion at neutral pH with near ultraviolet light produces hydrogen with high quantum yield. This same simple system may reduce carbon dioxide to formaldehyde and further products. These reactions offer a solution to the dilemma confronting the Oparin-Urey-Miller model of the chemical origin of life. If carbon dioxide is the main form of carbon on the primitive earth, the ferrous photoreaction may provide the reduced carbon necessary for the formation of amino acids and other biogenic molecules. These results suggest that this progenitor of modern photosynthesis may have contributed to the chemical origins of life.

Mauzerall, David C.

1990-01-01

205

Efficient near ultraviolet light induced formation of hydrogen by ferrous hydroxide. [in primitive earth  

NASA Technical Reports Server (NTRS)

A possible origin of early hydrogen by UV-induced photoreduction of ferrous ions was investigated by measuring the rate of H2 formation from irradiated FeSO4 solutions as a function of pH and the range of UV sources. It was found that, in addition to the known reaction in acid solution which decreases in yield with increasing pH and requires far-UV light, there is an efficient reaction occurring between pH 6 and 9 which utilizes near-UV light (of a 200-W mercury arc lamp). This latter reaction is a linear function of both the concentration of Fe(2+) and the light intensity. These results support the suggestion of Braterman et al. (1983) that the near-UV-driven photooxidation of ferrous ions may be responsible for the origin of the banded iron formations on the early earth. The efficient photoreaction could also explain the source of reducing equivalents for CO2 reduction.

Borowska, Zofia K.; Mauzerall, David C.

1987-01-01

206

Kinetics of the ferrous/ferric electrode reaction in the absence of chloride catalysis  

SciTech Connect

The kinetics of the ferrous ferric redox electrode reaction has been investigated by many workers as a simple, uncomplicated charge transfer reaction which seems ideal for testing experimental techniques and charge transfer theories. However, it has only recently been understood that very small traces of chloride can have a considerable effect on the reaction rate. The relation between the chloride content of the solution and the rate constant of the ferrous/ferric reaction on a gold electrode in perchloric acid solutions is confirmed in this work. The chloride effect free apparent standard rate constant is found to be 2.2 x 10/sup -5/ cm s/sup -1/, which is two to three orders of magnitude smaller than the rate constants normally reported for this reaction if the chloride content of the solution is not scrupulously controlled. Measurements were carried out by using two different in situ methods for cleaning the working electrode surface rather than employing extensive solution purification. In the first method the measuring electrode was potentiostated at sufficiently negative potentials to desorb the chloride from the surface followed by a potential step to the equilibrium potential and a pulse measurement of the kinetics. In the second method chloride ions were removed from the surface before and during the kinetic measurement by continuous oxidation of chromous ions added in small concentration to the test solution. Good agreement was found among the rate constants determined by these methods and a reported rate constant determined in ultraclean solution.

Hung, N.C.; Nagy, Z.

1987-09-01

207

Prospects for Ukrainian ferrous metals in the post-soviet period  

USGS Publications Warehouse

Two specialists on the mineral industries of the countries of the former USSR survey current problems confronting producers of ferrous metals in Ukraine and future prospects for domestic production and exports. A series of observations documenting the importance of ferrous metals production to Ukraine's economy is followed by sections describing investment plans and needs in the sector, and the role played by Ukraine within the iron and steel industry of the Soviet Union. The focus then turns to assessment of the current regional and global competitive position of Ukrainian producers for each of the major commodities of the sector-iron ore, manganese ore, ferroalloys, steel, and the products of the machine manufacturing and metal working industries. In conclusion, the paper discusses a potential regional industrial integration strategy analogous to that employed in the United States' Great Lakes/Midwest region, which possesses similar types of iron ore deposits and similar transport cost advantages and metallurgical and manufacturing industries. Journal of Economic Literature, Classification Numbers: F14, L61, L72. 1 table, 26 references.

Levine, R.M.; Bond, A.R.

1998-01-01

208

The effect of titanium and phosphorus on ferric/ferrous ratio in silicate melts: an experimental study  

NASA Astrophysics Data System (ADS)

The effect of TiO2 and P2O5 on the ferric/ferrous ratio in silicate melts was investigated in model silicate melts at air conditions in the temperature range 1,400-1,550 °C at 1-atm total pressure. The base composition of the anorthite-diopside eutectic composition was modified with 10 wt % Fe2O3 and variable amounts of TiO2 (up to 30 wt %) or P2O5 (up to 20 wt %). Some compositions also contained higher SiO2 concentrations to compare the role of SiO2, TiO2, and P2O5 on the Fe3+/Fe2+ ratio. The ferric/ferrous ratio in experimental glasses was analyzed using a wet chemical technique with colorimetric detection of ferrous iron. It is shown that at constant temperature, an increase in SiO2, TiO2, and P2O5 content results in a decrease in the ferric/ferrous ratio. The effects of TiO2 and SiO2 on the Fe3+/Fe2+ ratio was found to be almost identical. In contrast, adding P2O5 was found to decrease ferric/ferrous ratio much more effectively than adding silica. The results were compared with the predictions from the published empirical equations forecasting Fe3+/Fe2+ ratio. It was demonstrated that the effects of TiO2 are minor but that the effects of P2O5 should be included in models to better describe ferric/ferrous ratio in phosphorus-bearing silicate melts. Based on our observations, the determination of the prevailing fO2 in magmas from the Fe3+/Fe2+ ratio in natural glasses using empirical equations published so far is discussed critically.

Borisov, Alexander; Behrens, Harald; Holtz, Francois

2013-12-01

209

Chemical Fixation of Trace Elements in Coal Fly Ash using Ferrous Sulfate Treatment  

NASA Astrophysics Data System (ADS)

Coal fired electric power plants produce 50% of the electricity consumed in the US and generate large volumes of fly ash and other coal combustion by-products (CCBs). The majority of the CCB materials are disposed of in surface impoundments and landfills located throughout the US. Fly ash contains trace elements such as As, B, Cr, Mo, Ni, Se, Sr and V which can have a negative impact on the environment due to leaching by acid rain and groundwater with time. The potential release of these toxic trace elements into the environment is a big concern for the US power industry due to the high cost involved in lining the old and existing ash disposal sites. As a result, simple and effective treatment techniques are needed to stabilize the coal combustion by-products produced by power plants in the ash disposal sites and also to increase the use of coal fly ash for beneficial purposes. This paper reports the results of batch experiments designed to chemically treat coal fly ash with ferrous sulfate solution by promoting the formation of insoluble iron oxy- hydroxide phases that immobilize the toxic trace elements. Four fly ash samples, three acidic (HA, HB and MA) and one alkaline (PD), were treated with a ferrous sulfate (FS) solution (322 ppm Fe) and a ferrous sulfate + calcium carbonate (FS+CC) solution (322 ppm Fe and 28 ppm CaCO3) at solid:liquid ratios of 1:3 and 1:30. The effectiveness of this treatment technique was evaluated by the batch sequential leaching of treated and untreated coal fly ash samples using a synthetic acid rain (SAR) solution (USEPA Method 1312B) and also by a 7-step sequential chemical extraction procedure (SCEP) to understand the mechanism of treatment. The unbuffered FS solution at the 1:30 ratio was highly successful in reducing the mobility of the oxyanionic trace elements As (24-91%), Cr (82-97%), Mo (79-100%), Se (41-87%) and V (55-100%). However, the unbuffered FS treatment failed to reduce the mobility of B, Ni and Sr for the acidic fly ash samples. The buffered FS + CC solution greatly increased the mobility of the oxyanionic trace elements in the acidic fly ash samples, except for Cr in HA and HB fly ash. The buffered FS+CC solution reduced the mobility of all the trace elements except Ni in the alkaline PD fly ash. The ferrous sulfate treatment can be applied directly to the fresh fly ash produced in the electric power plants as well as to the fly ash already placed in the ash disposal facilities. A preliminary estimate indicates that ferrous sulfate treatment of fly ash at a power plant would be cost effective.

Bhattacharyya, S.; Donahoe, R. J.

2008-12-01

210

Questions and Answers: The NIH Trial of EDTA Chelation Therapy for Coronary Heart Disease  

MedlinePLUS

... still attain the treatment. What did the chelation infusions contain? For TACT, the active, 10-component chelation ... normal saline and 1.2 percent dextrose. The infusions for the study were prepared at a central ...

211

Adverse effects of iron supplementation: a comparative trial of a wax-matrix iron preparation and conventional ferrous sulfate tablets.  

PubMed

The acceptability of supplemental iron delivered from a wax-matrix tablet of ferrous sulfate was compared with that of a conventional ferrous sulfate tablet in a single-blind, parallel-group study. Both tablets were formulated to deliver 50 mg of elemental iron. The incidence of adverse effects was found to be significantly greater among 272 subjects taking the conventional tablets than among 271 subjects taking the wax-matrix preparation. Eighty-one percent of the subjects taking the wax-matrix preparation experienced no severe or moderate side effects as compared with only 50% of those taking the conventional tablets. PMID:4053146

Brock, C; Curry, H; Hanna, C; Knipfer, M; Taylor, L

1985-01-01

212

Synthesis and antiproliferating activity of iron chelators of hydroxyamino-1,3,5-triazine family  

Microsoft Academic Search

We synthesized and evaluated new specific tridentate iron(III) chelators of 2,6-bis[hydroxyamino]-1,3,5-triazine (BHT) family for use in iron deprivation cancer therapy. Physical properties of BHT chelators are easily customizable allowing easy penetration through cellular membranes. Antiproliferative activity of new BHT chelators was studied on MDA-MB-231 and MiaPaCa cells and compared to a clinically available new oral iron chelator, deferasirox (DFX). The

Daekyu Sun; Galina Melman; Nickolas J. LeTourneau; Allison M. Hays; Artem Melman

2010-01-01

213

Evaluation of intakes of transuranics influenced by chelation therapy  

SciTech Connect

Once an intake of transuranics occurs, there are only three therapeutic procedures available to the physician for reducing the intake and mitigating the dose: excision of material from wounds, removal of material from the lungs with lavage, and chelation therapy. The only chelation agents approved in the United States for the treatment of occupational intakes of transuranics are the zinc and calcium salts of diethylene-triamine-pentaacetic acid, better known as Zn-DTPA and Ca-DTPA. In the past 35 years, approximately 3000 doses of DTPA have been administrated to over 500 individuals who had intakes of transuranics. The drug is considered to be quiet safe and has few side effects. For the internal dosimetrist, perhaps the most important aspects of chelation therapy is that if enhances the excretion rate of a transuranic and perturbs the shape of the urinary excretion curve. These perturbations last for months and are so great that standard urinary excretion models cannot be used to evaluate the intake. We review here a method for evaluating intakes of transuranics influenced by chelation therapy that has been used with some degree of success at the Savannah River Site for over 20 years.

LaBone, T.R.

1994-02-01

214

Role of thermodynamic and kinetic parameters in gadolinium chelate stability.  

PubMed

In recent years there has been a renewed interest in the physicochemical properties of gadolinium chelates (GC). The aim of this review is to discuss the physicochemical properties of marketed GC with regard to possible biological consequences. GC can be classified according to three key molecular features: 1) the nature of the chelating moiety: either macrocyclic molecules in which Gd(3+) is caged in the preorganized cavity of the ligand, or linear, open-chain molecules; 2) ionicity: the ionicity of the molecule varies from neutral to tri-anionic agents; and 3) the presence or absence of an aromatic lipophilic moiety, which has a profound impact on the biodistribution of the GC. These parameters can also explain why GC differ considerably with regard to their thermodynamic stability constants and kinetic stability, as demonstrated by numerous studies. The concept of thermodynamic and kinetic stability is critically discussed, as it remains somewhat controversial, especially in predicting the amount of free gadolinium that may result from decomplexation of chelates in physiologic or pathologic situations. This review examines the possibility that the high kinetic stability provided by the macrocyclic structure combined with a high thermodynamic stability (reinforced by ionicity for macrocyclic chelates) can minimize the amount of free Gd(3+) released in the body. J. Magn. Reson. Imaging 2009;30:1249-1258. (c) 2009 Wiley-Liss, Inc. PMID:19938037

Idée, Jean-Marc; Port, Marc; Robic, Caroline; Medina, Christelle; Sabatou, Monique; Corot, Claire

2009-12-01

215

Fate and transport of ethylenediaminetetraacetate chelated contaminants in subsurface environments  

Microsoft Academic Search

Decontamination efforts during weapons production has historically involved the generation of mixed waste that was composed of organically chelated radionuclides. Waste disposal has traditionally involved shallow land burial, and not until recently has the subsurface migration of the organically complexed contaminants (co-contaminants) become a significant concern. The objective of this study was to provide an improved understanding of the geochemical

P. M. Jardine; D. L. Taylor

1995-01-01

216

Purification of Carboxypeptidase B by Zinc Chelate Chromatography  

Microsoft Academic Search

A method is described to purify pancreatic carboxypeptidases B (CPB), removing contaminating endoproteinases that interfere with use of CPB for carboxy-terminal analysis or modification of proteins. The separation uses zinc chelate chromatography and is based on the property that CPB has higher affinity for immobilized zinc ions than do serine proteinases such as trypsin and chymotrypsin. which are abundant endoproteolytic

G. L. Hortin; B. L. Gibson

1989-01-01

217

Synthesis and metal complexation properties of bisbenzospiropyran chelators in water  

Microsoft Academic Search

As a step towards developing a light-controlled reversible binding switch based on photochromic bisbenzospiropyran for investigating intracellular calcium signaling, substituted bisbenzospiropyran and phenolic chelators were synthesized and examined for metal binding strength. The complexation of these compounds with alkaline earth and zinc ions in methanol and buffer was characterized using NMR and luminescence spectroscopies. An increased length of convergent ligands

Satish Kumar; Cindy Chau; Gordon Chau; Alison McCurdy

2008-01-01

218

Sandstone Acidizing Using Chelating Agents and their Interaction with Clays  

E-print Network

................................................................. 87 3.2.3 Illite ............................................................................................. 102 3.2.3.1 Supernatant Analysis ....................................................... 102 3.2.3.2 Solid Analysis... ............................................................. 101 Figure 82 Silicon Concentration in Supernatant Plotted as a Function of HF Acid Concentrations for all Three Chelates Subjected to Static Solubility Tests with Illite ............................................................... 106...

George, Noble Thekkemelathethil 1987-

2013-01-09

219

ORIGINAL ARTICLE Chelated iron sources are inhibitors of Pseudomonas  

E-print Network

is a ubiquitous, Gram-negative human pathogen responsible for a variety of infections in immunocompromised humans-chelated iron were able to effectively thwart biofilm production in P. aeruginosa PA14 and in 20 clinical in an Anderson cascade impactor model of parti- cle size distribution in the human lung. Conclusions: Ferric

Hergenrother, Paul J.

220

ORIGINAL PAPER Chelators enhanced biocide inhibition of planktonic  

E-print Network

ORIGINAL PAPER Chelators enhanced biocide inhibition of planktonic sulfate-reducing bacterial of planktonic SRB growth. Desulfovibrio vulgaris ATCC 7757 and Desulfovibrio desulfuricans ATCC 14563 were grown was combined with glutaraldehyde or THPS, each of them enhanced the biocide inhibition of planktonic SRB growth

Gu, Tingyue

221

Screening Strategies for Iron Chelators in Serum Free Media  

Microsoft Academic Search

A variety of iron chelators, including recombinant human transferrin, were evaluated as replacements to holo human transferrin\\u000a on a number of industrially relevant cell lines (MDCK, BHK-21 and Vero). The results showed that short term screening over\\u000a one passage is not necessarily adequate to select a suitable transferrin replacement.

Joanne Keenan; Dermot Pearson; Martin Clynes

222

TREATMENT OF HEXAVALENT CHROMIUM IN CHROMITE ORE PROCESSING SOLID WASTE USING A MIXED REDUCTANT SOLUTION OF FERROUS SULFATE AND SODIUM DITHIONITE  

EPA Science Inventory

We developed a method for disseminating ferrous iron in the subsurface to enhance chemical reduction of hexavalent chromium (Cr(VI)) in a chromite ore processing solid waste derived from the production of ferrochrome alloy. The method utilizes ferrous sulfate (FeSO4) in combinati...

223

Field-Portable Immunoassay Instruments and Reagents to Measure Chelators and Mobile Forms of Uranium  

SciTech Connect

A collaborator in the Chemistry Department at Tulane University, Dr. Harry Ensley, has synthesized a new bifunctional chelator with specificity for ionic mercury (Hg2+) and methymercury (MeHg+). These chelators are based upon phenantholine derivative containing sulfhydryl functional groups. Experiments are underway to generate protein conjugates of this chelator to use in immunizations and screening.

Blake, Diane A.

2005-06-01

224

Lipophilic aroylhydrazone chelator HNTMB and its multiple effects on ovarian cancer cells  

Microsoft Academic Search

BACKGROUND: Metal chelators have gained much attention as potential anti-cancer agents. However, the effects of chelators are often linked solely to their capacity to bind iron while the potential complexation of other trace metals has not been fully investigated. In present study, we evaluated the effects of various lipophilic aroylhydrazone chelators (AHC), including novel compound HNTMB, on various ovarian cancer

Kyu Kwang Kim; Thilo S Lange; Rakesh K Singh; Laurent Brard

2010-01-01

225

Molecular mechanisms of in vivo metal chelation: implications for clinical treatment of metal intoxications.  

PubMed Central

Successful in vivo chelation treatment of metal intoxication requires that a significant fraction of the administered chelator in fact chelate the toxic metal. This depends on metal, chelator, and organism-related factors (e.g., ionic diameter, ring size and deformability, hardness/softness of electron donors and acceptors, route of administration, bioavailability, metabolism, organ and intra/extracellular compartmentalization, and excretion). In vivo chelation is not necessarily an equilibrium reaction, determined by the standard stability constant, because rate effects and ligand exchange reactions considerably influence complex formation. Hydrophilic chelators most effectively promote renal metal excretion, but they complex intracellular metal deposits inefficiently. Lipophilic chelators can decrease intracellular stores but may redistribute toxic metals to, for example, the brain. In chronic metal-induced disease, where life-long chelation may be necessary, possible toxicity or side effects of the administered chelator may be limiting. The metal selectivity of chelators is important because of the risk of depletion of the patient's stores of essential metals. Dimercaptosuccinic acid and dimercaptopropionic sulfonate have gained more general acceptance among clinicians, undoubtedly improving the management of many human metal intoxications, including lead, arsenic, and mercury compounds. Still, development of new safer chelators suited for long-term oral administration for chelation of metal deposits (mainly iron), is an important research challenge for the future. PMID:12426153

Andersen, Ole; Aaseth, Jan

2002-01-01

226

Tests of stability on waste produced in pilot plant testing using ferrous{center_dot}EDTA and magnesium-enhanced lime for combined SO{sub 2}/NO{sub x} removal  

SciTech Connect

A pilot-plant-scale study of combined sulfur dioxide/nitrogen oxides (SO{sub 2}/NO{sub x}) removal has been performed by the Dravo Lime Company at the Cincinnati Gas and Electric Company`s Miami Fort Station in North Bend, Ohio. This study used Dravo`s patented Thiosorbic{reg_sign} lime process, utilizing a magnesium-enhanced lime, along with Argonne National Laboratory`s (ANL`s) patented ARGONOX metal-chelate additive, ferrous{center_dot}ethylenediaminetetraacetic acid (Fe{center_dot}EDTA). For approximately nine months, scrubbing tests were carried out, and waste samples were collected. Waste testing at ANL involved two types of long-term chemical stability experiments. In one experiment, the gas-phase composition above several different samples was studied by mass spectrometry over a period of about 22 months. Significant changes were noted for oxygen (O{sub 2}), carbon dioxide (CO{sub 2}), and hydrogen sulfide (H{sub 2}S) gases. The other experiment involved solid-phase leaching using the Toxicity Characteristic Leaching Procedure (TCLP). Samples were stored for up to 14 months before leaching. Then each leachate was tested for total Kjeldahl nitrogen and for some nitrogen-containing species. Total leachable nitrogen was found to stabilize after about the first seven months of storage.

Mendelsohn, M.H.; Livengood, C.D.

1994-03-01

227

Chelator induced phytoextraction and in situ soil washing of Cu.  

PubMed

In a soil column experiment, we investigated the effect of 5 mmol kg(-1) soil addition of citric acid, ethylenediamine tetraacetate (EDTA), diethylenetriamine-pentaacetate (DTPA) and [S,S]-stereoisomer of ethylenediamine-disuccinate (EDDS) on phytoextraction of Cu from a vineyard soil with 162.6 mg kg(-1) Cu, into the test plant Brassica rapa var. pekinensis. We also examined the use of a horizontal permeable barrier, composed of layers of nutrient enriched sawdust and apatite, for reduction of chelator induced Cu leaching. The addition of all chelators, except citric acid, enhanced Cu mobility and caused leaching of 19.5-23% of initial total Cu from the soil column. However, Cu plant uptake did not increase accordingly; the most effective was the EDDS treatment, in which plant Cu concentration reached 37.8 +/-1.3 mg kg(-1) Cu and increased by 3.3-times over the control treatment. The addition of none of the chelators in the concentration range from 5 to 15 mmol kg(-1) exerted any toxic effect on respiratory soil microorganisms. When EDDS was applied into the columns with horizontal permeable barriers, only 0.53 +/- 0.32% of the initial total Cu was leached. Cu (36.7%) was washed from the 18 cm soil layer above the barrier and accumulated in the barrier. Our results indicate that rather than for a reduction of Cu leaching during rather ineffective chelate induced Cu phytoextraction, horizontal permeable barriers could be more effective in a new remediation technique of controlled in situ soil washing of Cu with biodegradable chelates. PMID:15312945

Kos, Bostjan; Lestan, Domen

2004-11-01

228

Dissolution of Nickel Ferrite in Aqueous Solutions Containing Oxalic Acid and Ferrous Salts.  

PubMed

The dissolution of nickel ferrite in oxalic acid and in ferrous oxalate-oxalic acid aqueous solution was studied. Nickel ferrite was synthesized by thermal decomposition of a mixed tartrate; the particles were shown to be coated with a thin ferric oxide layer. Dissolution takes place in two stages, the first one corresponding to the dissolution of the ferric oxide outer layer and the second one being the dissolution of Ni(1.06)Fe(1.96)O(4). The kinetics of dissolution during this first stage is typical of ferric oxides: in oxalic acid, both a ligand-assisted and a redox mechanism operates, whereas in the presence of ferrous ions, redox catalysis leads to a faster dissolution. The rate dependence on both oxalic acid and on ferrous ion is described by the Langmuir-Hinshelwood equation; the best fitting corresponds to K(1)(ads)=25.6 mol(-1) dm(-3) and k(1)(max)=9.17x10(-7) mol m(-2) s(-1) and K(2)(ads)=37.1x10(3) mol(-1) dm(-3) and k(2)(max)=62.3x10(-7) mol m(-2) s(-1), respectively. In the second stage, Langmuir-Hinshelwood kinetics also describes the dissolution of iron and nickel from nickel ferrite, with K(1)(ads)=20.8 mol(-1) dm(3) and K(2)(ads)=1.16x10(5) mol(-1) dm(3). For iron, k(1)(max)=1.02x10(-7) mol of Fe m(-2) s(-1) and k(2)(max)=2.38x10(-7) mol of Fe m(-2) s(-1); for nickel, the rate constants k(1)(max) and k(2)(max) are 2.4 and 1.79 times smaller, respectively. The factor 1.79 agrees nicely with the stoichiometric ratio, whereas the factor 2.4 implies the accumulation of some nickel in the residual particles. The rate of nickel dissolution in oxalic acid is higher than that in bunsenite by a factor of 8, whereas hematite is more reactive by a factor of 9 (in the absence of Fe(II)) and 27 (in the presence of Fe (II)). It may be concluded that oxalic acid operates to dissolve iron, and the ensuing disruption of the solid framework accelerates the release of nickel. Copyright 2000 Academic Press. PMID:11254279

Figueroa, Carlos A.; Sileo, Elsa E.; Morando, Pedro J.; Blesa, Miguel A.

2000-05-15

229

Iron fortification technology development: new approaches.  

PubMed

The objective of our fortification technology development has been to deliver meaningful levels of bioavailable iron via commonly consumed foods and beverages without compromising taste, appearance, and stability. However, fortification of foods is accompanied with unsolved problems such as unacceptable taste, color, stability, and bioavailability. To solve these problems, we developed a fortification technology that prevents the iron-mediated undesirable taste and appearance of the final product while preserving stability and bioavailability. Iron was stabilized by applying principles of colloid chemistry (encapsulation), chelation, and electrochemical chemistry (redox modulation). Results from color and sensory evaluations showed that formulation of products using the new fortification technology known as "GrowthPlus" eliminated detrimental effects on taste, appearance, and product stability. Bioavailability evaluation using animal models and human subjects showed the GrowthPlus technology does not interfere with the bioavailability of iron from either ferrous bis-glycinate or ferrous fumarate. Multiple intervention trials showed that repeated consumption of the redox stabilized iron in the form of a powdered fruit beverage increased iron status indicators (hemoglobin and ferritin) and reduced iron deficiency anemia significantly in school children, adolescent girls, and pregnant women. PMID:16549477

Mehansho, Haile

2006-04-01

230

Chemical Cleaning of a Brass-Tubed Turbine Condenser after Five Years of Operation with Ferrous Sulphate Dosing.  

National Technical Information Service (NTIS)

The purpose of chemically cleaning the brass-tubed turbine condenser was to remove the ferrous oxide layer and corrosion products which are mainly copper oxide Cu sub 2 O. Laboratory tests were conducted where 1 m long pieces of tube were installed in a s...

H. Gutberlet

1983-01-01

231

Spectroscopic characterization of nitrosylheme in nitric oxide complexes of ferric and ferrous cytochrome c' from photosynthetic bacteria.  

PubMed

Reactions of ferric and ferrous cytochromes c' from four photosynthetic bacteria (Rhodobacter capsulatus ATCC 11166, Rhodopseudomonas palustris ATCC 17001, Rhodospirillum rubrum ATCC 11170, and Chromatium vinosum ATCC 17899) with nitric oxide have been investigated by electronic absorption and electron paramagnetic resonance spectroscopies. The heme iron(III) of these ferric cytochromes c' has been recently reported to be in a quantum mechanically admixed (S = 5/2, 3/2) state [Fujii, S., Yoshimura, T., Kamada, H., Yamaguchi, K., Suzuki, S., Shidara, S. and Takakuwa, S. (1995) Biochim. Biophys. Acta 1251, 161-169]. The affinity of ferric cytochromes c' for NO among these bacterial species (C. vinosum > Rps. palustris approximately Rb. capsulatus > R. rubrum) was apparently related to the S = 3/2 content in the or der. In the reaction of ferrous cytochrome c' with NO, six- and five-coordinated nitrosylhemes, which represent species with and without a ligand at the axial position trans to nitrosyl group, have been formed. The content of six-coordinated nitrosylheme in NO-ferrous cytochrome c' has been determined to be Rb. capsulatus approximately Rps. palustris > C. vinosum < R rubrum, suggesting that a stability of iron-to-histidine bond decreases with this order. The NO reactions of ferric and ferrous cytochromes c' from photosynthetic bacteria have been compared with those of cytochromes c' from denitrifying bacteria. PMID:8547347

Yoshimura, T; Fujii, S; Kamada, H; Yamaguchi, K; Suzuki, S; Shidara, S; Takakuwa, S

1996-01-01

232

A new method for preparation of magnetite from iron oxyhydroxide or iron oxide and ferrous salt in aqueous solution  

NASA Astrophysics Data System (ADS)

In this study, a new method is proposed for the preparation of Fe 3O 4 from iron oxyhydroxides (goethite, akaganeite, lepidocrocite, feroxyhyte and ferrihydrite) or iron oxide (hematite) and ferrous salt in aqueous solution. The product is magnetite with various particle sizes. Products are characterized by X-ray powder diffraction, IR spectra and vibrating sample magnetometery.

Kahani, S. A.; Jafari, M.

2009-07-01

233

Arsenic Encapsulation Using Portland Cement With Ferrous Sulfate/Lime And Terra-BondTM Technologies - Microcharacterization And Leaching Studies  

EPA Science Inventory

This work reports the results of an investigation on the treatment and encapsulation of arsenic-containing materials by Portland cement with ferrous sulfate and lime (PFL) and Terra-BondTM, a commercially available patented technology. The arsenic materials treated we...

234

INJECTION OF A FERROUS SULFATE/SODIUM DITHIONITE REDUCTANT FOR IN-SITU TREATMENT OF HEXAVALENT CHROMIUM  

EPA Science Inventory

An in situ pilot study was conducted to evaluate the performance of a ferrous iron-based reductant solution in treating hexavalent chromium within a saturated zone source area at a former industrial site in Charleston, South Carolina (USA). The hexavalent source area, consisting...

235

Modelling of ferrous sulphate oxidation by Thiobacillus ferrooxidans in discontinuous culture: Influence of temperature, pH and agitation rate  

Microsoft Academic Search

This paper studies the temperature effect on the specific growth rate of the microorganisms (?c) as particular aspect of the mathematical relationships between ?c of Thiobacillus ferrooxidans and the concentrations of substrate (ferrous iron) and product (ferric iron). Until now, there have been few studies of this relationship; also, there has been little work studying the influence of temperature on

JoséManuel Gómez; Domingo Cantero

1998-01-01

236

Use of a Ferrous Sulfate - Sodium Dithionite Blend to Treat a Dissolved Phase Cr(VI) Plume  

EPA Science Inventory

A field study was conducted to evaluate the use of a combination of sodium dithionite and ferrous sulfate in creating an in situ redox zone for treatment of a dissolved phase Cr(VI) plume at a former industrial site. The reductant blend was injected into the path of a dissolved ...

237

Application of cross-flow ultrafiltration for the determination of colloidal abundances in suboxic ferrous-rich ground waters  

E-print Network

Application of cross-flow ultrafiltration for the determination of colloidal abundances in suboxic ferrous-rich ground waters Martin Hassellöv a,b,, Ken O. Buesseler a , Steven M. Pike a , Minhan Dai a-flow ultrafiltration (CFF) system equipped with a 1 kDa CFF membrane. By purging the CFF system with nitrogen

Buesseler, Ken

238

Plutonium-uranium separation in the Purex process using mixtures of hydroxylamine nitrate and ferrous sulfamate  

SciTech Connect

Laboratory studies, followed by plant operation, established that a mixture of hydroxylamine nitrate (HAN) and ferrous sulfamate (FS) is superior to FS used alone as a reductant for plutonium in the Purex first cycle. FS usage has been reduced by about 70% (from 0.12 to 0.04M) compared to the pre-1978 period. This reduced the volume of neutralized waste due to FS by 194 liters/metric ton of uranium (MTU) processed. The new flowsheet also gives lower plutonium losses to waste and at least comparable fission product decontamination. To achieve satisfactory performance at this low concentration of FS, the acidity in the 1B mixer-settler was reduced by using a split-scrub - a low acid scrub in stage one and a higher acid scrub in stage three - to remove acid from the solvent exiting the 1A centrifugal contactor. 8 references, 14 figures, 1 table.

McKibben, J.M.; Chostner, D.F.; Orebaugh, E.G.

1983-11-01

239

Iron oxide and hydroxide precipitation from ferrous solutions and its relevance to Martian surface mineralogy  

NASA Astrophysics Data System (ADS)

Experiments were performed to examine if the ubiquitousness of a weak magnetic component in all Martian surface fines tested with the Viking Landers can be attributed to ferric iron precipitation in aqueous solution under oxidizing conditions at neutral pH. Ferrous solutions were mixed in deionized water and various minerals were added to separate liquid samples. The iron-bearing additives included hematite, goethite, magnetite, maghemite, lepidocrocite and potassium bromide blank at varying concentrations. IR spectroscopic scans were made to identify any precipitates resulting from bubbling oxygen throughout the solutions; the magnetic properties of the precipitates were also examined. The data indicated that the lepidocrocite may have been preferentially precipitated, then aged to maghemite. The process would account for the presumed thin residue of maghemite on the present Martian surface, long after abundant liquid water on the Martian surface vanished.

Posey-Dowty, J.; Moskowitz, B.; Crerar, D.; Hargraves, R.; Tanenbaum, L.; Dowty, E.

1986-04-01

240

X-ray Spectroscopic Study of Solvent Effects on the Ferrous and Ferric Hexacyanide Anions.  

PubMed

We present an Fe K? resonant inelastic X-ray scattering (RIXS) and X-ray emission (XES) study of ferrous and ferric hexacyanide dissolved in water and ethylene glycol. We observe that transitions below the absorption edge show that the solvent has a distinct effect on the valence electronic structure. In addition, both the RIXS and XES spectra show a stabilization of the 2p levels when dissolved in water. Using molecular dynamics simulations, we propose that this effect arises from the hydrogen-bonding interactions between the complex and nearby solvent molecules. This withdraws electron density from the ligands, stabilizing the complex but also causing a slight increase in ?-backbonding. PMID:25223627

Penfold, T J; Reinhard, M; Rittmann-Frank, M H; Tavernelli, I; Rothlisberger, U; Milne, C J; Glatzel, P; Chergui, M

2014-10-01

241

Evaluation of a ferrous benzoic xylenol orange transparent PVA cryogel radiochromic dosimeter.  

PubMed

A stable cryogel dosimeter was prepared using ferrous benzoic xylenol orange (FBX) in a transparent poly-(vinyl alcohol) (PVA) cryogel matrix. Dose response was evaluated for different numbers of freeze-thaw cycles (FTCs), different concentrations of PVA, and ratios of water/dimethyl sulfoxide. Linear relationships between dose and absorbance were obtained in the range of 0-1000 cGy for all formulations. Increasing the concentration of PVA and number of FTCs resulted in increased absorbance and sensitivity. The effects of energy and dose rate were also evaluated. No significant dose rate dependence was observed over the range 1.05 to 6.33 Gy min(-1). No energy response was observed over photon energies of 6, 10, and 18 MV. PMID:24619200

Eyadeh, Molham M; Farrell, Thomas J; Diamond, Kevin R

2014-04-01

242

Evaluation of a ferrous benzoic xylenol orange transparent PVA cryogel radiochromic dosimeter  

NASA Astrophysics Data System (ADS)

A stable cryogel dosimeter was prepared using ferrous benzoic xylenol orange (FBX) in a transparent poly-(vinyl alcohol) (PVA) cryogel matrix. Dose response was evaluated for different numbers of freeze-thaw cycles (FTCs), different concentrations of PVA, and ratios of water/dimethyl sulfoxide. Linear relationships between dose and absorbance were obtained in the range of 0-1000 cGy for all formulations. Increasing the concentration of PVA and number of FTCs resulted in increased absorbance and sensitivity. The effects of energy and dose rate were also evaluated. No significant dose rate dependence was observed over the range 1.05 to 6.33 Gy min-1. No energy response was observed over photon energies of 6, 10, and 18 MV.

Eyadeh, Molham M.; Farrell, Thomas J.; Diamond, Kevin R.

2014-04-01

243

In situ synthesis of TiC reinforcements in ferrous matrix  

SciTech Connect

The addition of ceramic particles to ferrous matrix dramatically changes the properties of the alloy and consequently its behavior in services. By judicious selection of hard carbides such as TiC in iron matrix, it is possible to design metal matrix composites which can withstand high abrasive wear environments. In this paper the authors highlight a novel in situ technique of producing TiC reinforcements in iron matrix. The paper also discusses the highly exothermic chemical reaction of TiC formation which is moderated by the availability of carbon in the molten metal. Shrinking core model to explain the reaction paths, solidification rate and rate limiting steps in the formation of TiC are proposed. The paper concludes with the definite note on the crystallographic growth direction of in situ produced TiC in the matrix.

Raghunath, C.; Bhat, M.S. [Univ. of Arizona, Tucson, AZ (United States). Dept. of Materials Science and Engineering

1995-08-01

244

Mechanism of formation of magnetite from ferrous hydroxide in aqueous corrosion processes  

NASA Astrophysics Data System (ADS)

The stoichiometric conditions for the formation of ferrous hydroxide Fe(OH)2, by mixing Fe2+ ions with caustic soda NaOH, leads by oxidation to magnetite, irrelevant of the foreign anions, e.g. Cl- or SO4 2-, as demonstrated from Mössbauer spectroscopy. The electrochemical potential Eh and pH value of the initial conditions correspond to the drastic change from basic to acidic medium, observed when varying the initial Fe2+/OH- ratio. Mössbauer analysis of the end products of oxidation at various temperatures shows that magnetite is only obtained at stoichiometry at very low temperature, but extends off stoichiometry at higher temperatures. The mechanism of formation of magnetite through an intermediate compound is discussed.

Olowe, A. A.; Rezel, D.; Génin, J. M. R.

1989-03-01

245

Inhibition of bacterial oxidation of ferrous iron by lead nitrate in sulfate-rich systems  

USGS Publications Warehouse

Inhibition of bacterial oxidation of ferrous iron (Fe(II)) by Pb(NO3)2 was investigated with a mixed culture of Acidithiobacillus ferrooxidans. The culture was incubated at 30 °C in ferrous-sulfate medium amended with 0–24.2 mM Pb(II) added as Pb(NO3)2. Anglesite (PbSO4) precipitated immediately upon Pb addition and was the only solid phase detected in the abiotic controls. Both anglesite and jarosite (KFe3(SO4)2(OH)6) were detected in inoculated cultures. Precipitation of anglesite maintained dissolved Pb concentrations at 16.9–17.6 ?M regardless of the concentrations of Pb(NO3)2 added. Fe(II) oxidation was suppressed by 24.2 mM Pb(NO3)2 addition even when anglesite was removed before inoculation. Experiments with 0–48 mM KNO3 demonstrated that bacterial Fe(II) oxidation decreased as nitrate concentration increased. Therefore, inhibition of Fe(II) oxidation at 24.2 mM Pb(NO3)2 addition resulted from nitrate toxicity instead of Pb addition. Geochemical modeling that considered the initial precipitation of anglesite to equilibrium followed by progressive oxidation of Fe(II) and the precipitation of jarosite and an amorphous iron hydroxide phase, without allowing plumbojarosite to precipitate were consistent with the experimental time-series data on Fe(II) oxidation under biotic conditions. Anglesite precipitation in mine tailings and other sulfate-rich systems maintains dissolved Pb concentrations below the toxicity threshold of A. ferrooxidans.

Wang, Hongmei; Gong, Linfeng; Cravotta, Charles A.; Yang, Xiaofen; Tuovinen, Olli H.; Dong, Hailiang; Fu, Xiang

2013-01-01

246

Functional characterization of LIT1, the Leishmania amazonensis ferrous iron transporter.  

PubMed

Leishmania amazonensis LIT1 was identified based on homology with IRT1, a ferrous iron transporter from Arabidopsis thaliana. Deltalit1L. amazonensis are defective in intracellular replication and lesion formation in vivo, a virulence phenotype attributed to defective intracellular iron acquisition. Here we functionally characterize LIT1, directly demonstrating that it functions as a ferrous iron membrane transporter from the ZIP family. Conserved residues in the predicted transmembrane domains II, IV, V and VII of LIT1 are essential for iron transport in yeast, including histidines that were proposed to function as metal ligands in ZIP transporters. LIT1 also contains two regions within the predicted intracellular loop that are not found in Arabidopsis IRT1. Deletion of region I inhibited LIT1 expression on the surface of Leishmania promastigotes. Deletion of region II did not interfere with LIT1 trafficking to the surface, but abolished its iron transport capacity when expressed in yeast. Mutagenesis revealed two motifs within region II, HGHQH and TPPRDM, that are independently required for iron transport by LIT1. D263 was identified as a key residue required for iron transport within the TPPRDM motif, while P260 and P261 were dispensable. Deletion of proline-rich regions within region I and between regions I and II did not affect iron transport in yeast, but in L. amazonensis were not able to rescue the intracellular growth of Deltalit1 parasites, or their ability to form lesions in mice. These results are consistent with a potential role of the unique intracellular loop of LIT1 in intracellular regulation by Leishmania-specific factors. PMID:20025906

Jacques, Ismaele; Andrews, Norma W; Huynh, Chau

2010-03-01

247

Altered APP Carboxyl-Terminal Processing Under Ferrous Iron Treatment in PC12 Cells  

PubMed Central

Amyloid-? peptide (A?), generated by proteolytic cleavage of the amyloid precursor protein (APP), plays a pivotal role in the pathogenesis of Alzheimer's disease (AD). The key step in the generation of A? is cleavage of APP by beta-site APP-cleaving enzyme 1 (BACE1). Levels of BACE1 are increased in vulnerable regions of the AD brain, but the underlying mechanism is unknown. In the present study, we reported the effects of ferrous ions at subtoxic concentrations on the mRNA levels of BACE1 and a-disintegrin-and-metalloproteinase 10 (ADAM10) in PC12 cells and the cell responses to ferrous ions. The cell survival in PC12 cells significantly decreased with 0 to 0.3 mM FeCl2, with 0.6 mM FeCl2 treatment resulting in significant reductions by about 75%. 4,6-diamidino-2-phenylindole (DAPI) staining showed that the nuclei appeared fragmented in 0.2 and 0.3 mM FeCl2. APP-?-carboxyl terminal fragment (APP-?-CTF) associations with ADAM10 and APP-?-CTF with BACE1 were increased. Levels of ADAM10 and BACE1 mRNA increased in response to the concentrations of 0.25 mM, respectively. In addition, p-ERK and p-Bad (S112, S155) expressions were increased, suggesting that APP-CTF formation is related to ADAM10/BACE1 expression. Levels of Bcl-2 protein were increased, but significant changes were not observed in the expression of Bax. These data suggest that ion-induced enhanced expression of AMDA10/BACE1 could be one of the causes for APP-?/?-CTF activation. PMID:23776394

Kim, Chi Hyun

2013-01-01

248

Chelating compounds as potential flash rust inhibitors and melamine & aziridine cure of acrylic colloidal unimolecular polymers (CUPs)  

NASA Astrophysics Data System (ADS)

Waterborne coatings on ferrous substrates usually show flash rusting which decreases the adhesion of the coating and the corrosion products can form a stain. Chelating compounds were investigated as potential flash rust inhibitors. Compounds being evaluated include amine alcohols, diamines and sulfur containing amines. A new corrosion inhibitor 2,5-bis(thioaceticacid)-1,3,4-thiadiazole (H2ADTZ) was synthesized and its performance characteristics were evaluated. It was noted that the observed structure of 1,3,4-thiadiazolidine-2,5-dithione (also known as 2,5-dimercapto-1,3,4-thiadiazole (DMTD or DMcT)) has been previously reported in three different tautomeric forms including -dithiol and -dithione. The relative stability of each form as well as the synthesis and characterization of the structures of mono- and dialkylated forms of 5-mercapto-1,3,4-thiadiazole-2(3H)-thione (MTT) were examined. The methods of X-ray crystallography, NMR spectroscopy and ab-initio electronic structure calculations were combined to understand the reactivity and structure of each compound. Polymers were synthesized with a 1:7 or 1:8 ratio of acrylic acid to acrylate monomers to produce an acid rich resin. The polymers were reduced and solvent stripped to produce Colloidal Unimolecular Polymers (CUPs). These particles are typically 3-9 nanometers in diameter depending upon the molecular weight. They were then formulated into a clear coating with either a melamine (bake) or an aziridine (ambient cure) and then cured. The melamine system was solvent free, a near zero VOC and the aziridine system was very low to near zero VOC. The coatings were evaluated for their MEK resistance, adhesion, hardness, gloss, flexibility, wet adhesion, abrasion and impact resistance properties.

Mistry, Jigar Kishorkumar

249

Iron chelation: a potential therapeutic strategy in oesophageal cancer.  

PubMed

Raised intracellular iron has been identified as a potential aetiological factor in the development of several epithelial malignancies, including those of the gastrointestinal tract. The mechanism behind this increase is thought to include disorders of iron uptake and storage. Several iron chelators have been identified as potential anti-tumour agents, with much work undertaken to ascertain the exact mode of action. Despite this, there is little known about the role that these drugs play in the cellular iron metabolism of oesophageal cancer. Consequently, the present study looks to review the relationship of two clinically important iron-chelating agents, deferoxamine and deferasirox, on cellular iron uptake and storage in oesophageal squamous and adenocarcinoma. This provides important evidence for the debate about the role these agents have in the clinical management of such tumours. PMID:23278384

Keeler, B D; Brookes, M J

2013-03-01

250

MULTIDENTATE TEREPHTHALAMIDATE AND HYDROXYPYRIDONATE LIGANDS: TOWARDS NEW ORALLY ACTIVE CHELATORS  

SciTech Connect

The limitations of current therapies for the treatment of iron overload or radioisotope contamination have stimulated efforts to develop new orally bioavailable iron and actinide chelators. Siderophore-inspired tetradentate, hexadentate and octadentate terephthalamidate and hydroxypyridonate ligands were evaluated in vivo as selective and efficacious iron or actinide chelating agents, with several metal loading and ligand assessment procedures, using {sup 59}Fe, {sup 238}Pu, and {sup 241}Am as radioactive tracers. The compounds presented in this study were compared to commercially available therapeutic sequestering agents [deferoxamine (DFO) for iron and diethylenetriaminepentaacetic acid (DPTA) for actinides] and are unrivaled in terms of affinity, selectivity and decorporation efficacy, which attests to the fact that high metal affinity may overcome the low bioavailability properties commonly associated to multidenticity.

Abergel, Rebecca J.; Raymond, Kenneth N.

2011-07-13

251

Doping of graphene nanomeshes by ion-chelation  

NASA Astrophysics Data System (ADS)

Graphene nanomeshes (GNM's) are formed by the creation of a superlattice of pores in graphene. Depending upon the pore shape, size, superlattice constant and symmetry, GNM's can be semimetallic, or semiconducting with a fractional eV band gap, allowing them to be fruitfully employed in applications that pristine graphene cannot. In this work, first principles calculations are used to study the doping of semiconducting GNM's using a chemically motivated approach. It is shown that ion-chelation leads to a stable doping of the GNM's, and that it occurs within a rigid band doping picture. Such chelated or ``crown'' GNM structures are thus stable, high mobility semiconducting materials which can serve as building blocks for novel graphene-based nanoelectronics applications.

Maarouf, Ahmed; Nistor, Razvan; Afzali, Ali; Kuroda, Marcelo; Newns, Dennis; Martyna, Glenn

2013-03-01

252

Ulceration of the oral mucosa following direct contact with ferrous sulfate in elderly patients: a case report and a review of the French National Pharmacovigilance Database  

PubMed Central

Objective To report a series of cases of ulceration of the oral mucosa linked to direct contact with ferrous sulfate in elderly patients. Case summary The first case report concerns the occurrence of widespread oral ulceration in an 87-year-old woman with Alzheimer’s disease. The ulceration extended from the side of the tongue to the floor of the mouth. No clear explanation was found and various local treatments were ineffective. Once it was realized that the ferrous sulfate tablets (given as an iron supplement) were crushed prior to administration (due to the patient’s deglutition disorder), withdrawal of this treatment led to rapid resolution of the ulceration. Nine other cases of oral ulcerations associated with ferrous sulfate were identified in the French National Pharmacovigilance Database. All but one of the patients were over 80 years of age and the youngest patient (a 54-year-old) had dysphagia associated with facial paralysis. Discussion Only two other reports of oral ulceration due to ferrous sulfate have been published to date. Mucosal toxicity of ferrous sulfate (which is probably related to oxidative stress) has previously been reported for the hypopharynx, the esophageal lumen, and (after inhalation of a tablet) the tracheobronchial tree. Conclusion The mucosal toxicity of ferrous sulfate must be taken into account when deglutition disorders are present (as in elderly patients) and appropriate pharmaceutical formulations (such as syrups) should be administered to at-risk patients. The use of iron salts other than ferrous sulfate could be considered. PMID:24812499

Liabeuf, Sophie; Gras, Valerie; Moragny, Julien; Laroche, Marie-Laure; Andrejak, Michel

2014-01-01

253

Extraction of heavy metals from soils using biodegradable chelating agents.  

PubMed

Metal pollution of soils is widespread across the globe, and the clean up of these soils is a difficulttask. One possible remediation technique is ex-situ soil washing using chelating agents. Ethylenediaminetetraacetic acid (EDTA) is a very effective chelating agent for this purpose but has the disadvantage that it is quite persistent in the environment due to its low biodegradability. The aim of our work was to investigate the biodegradable chelating agents [S,S]-ethylenediaminedisuccinic acid (EDDS), iminodisuccinic acid (IDSA), methylglycine diacetic acid (MGDA), and nitrilotriacetic acid (NTA) as potential alternatives and compare them with EDTA for effectiveness. Kinetic experiments showed for all metals and soils that 24 h was the optimum extraction time. Longer times only gave minor additional benefits for heavy metal extraction but an unwanted increase in iron mobilization. For Cu at pH 7, the order of the extraction efficiency for equimolar ratios of chelating agent to metal was EDDS > NTA> IDSA > MGDA > EDTA and for Zn it was NTA > EDDS > EDTA >MGDA > IDSA. The comparatively low efficiency of EDTA resulted from competition between the heavy metals and co-extracted Ca. For Pb the order of extraction was EDTA > NTA >EDDS due to the much stronger complexation of Pb by EDTA compared to EDDS. At higher concentration of complexing agent, less difference between the agents was found and less pH dependence. There was an increase in heavy metal extraction with decreasing pH, but this was offset by an increase in Ca and Fe extraction. In sequential extractions EDDS extracted metals almost exclusively from the exchangeable, mobile, and Mn-oxide fractions. We conclude that the extraction with EDDS at pH 7 showed the best compromise between extraction efficiency for Cu, Zn, and Pb and loss of Ca and Fe from the soil. PMID:14968886

Tandy, Susan; Bossart, Karin; Mueller, Roland; Ritschel, Jens; Hauser, Lukas; Schulin, Rainer; Nowack, Bernd

2004-02-01

254

Chelate-Assisted Heavy Metal Movement Through the Root Zone  

NASA Astrophysics Data System (ADS)

Chelating agents are added to soil as a means to mobilize heavy metals for plant uptake during phytoremediation. Yet almost no studies follow the displacement of heavy metals through the vadose zone following solubilization with chelating agents. The objective of this work was to determine the movement of heavy metals through the soil profile and their absorption by barley (Hordeum vulgare L.) in a soil amended with biosolids and in the presence of a chelating agent (EDTA). Twelve columns 75 cm in height and 17 in diameter were packed with a Haynie very fine sandy loam (coarse-silty, mixed, calcareous, mesic Mollic Udifluvents) and watered with liquid biosolids applied at the surface at a rate of 120 kg N/ha. Three weeks after plants germinated, soil was irrigated with a solution of the disodium salt of EDTA added at a rate of 0.5 g/kg soil. Four treatments were imposed: columns with no plants and no EDTA; columns with no plants plus EDTA; columns with plants and no EDTA; and columns with plants and EDTA. Columns were watered intensively for 35 days until two pore volumes of water had been added, and the leachates were collected daily. With or without plants, columns with EDTA had lower total concentrations of Cu, Zn, Cd, Ni, and Pb in the surface 20 cm than columns without EDTA. Concentrations of the heavy metals in this layer were not afffected by the presence of roots. Iron in leachate was followed as an indicator metal for movement to groundwater. No iron appeared in the leachate without EDTA, either in the columns with plants or without plants. The peak concentration of iron in the leachate occurred three days earlier in the columns without plants and EDTA compared to the columns with plants and EDTA. The results indicated the importance of vegetation on retarding heavy metal leaching to groundwater during chelate-facilitated phytoremediation.

Kirkham, M.; Madrid, F.; Liphadzi, M. S.

2001-12-01

255

Targeting Chelatable Iron as a Therapeutic Modality in Parkinson's Disease  

PubMed Central

Abstract Aims: The pathophysiological role of iron in Parkinson's disease (PD) was assessed by a chelation strategy aimed at reducing oxidative damage associated with regional iron deposition without affecting circulating metals. Translational cell and animal models provided concept proofs and a delayed-start (DS) treatment paradigm, the basis for preliminary clinical assessments. Results: For translational studies, we assessed the effect of oxidative insults in mice systemically prechelated with deferiprone (DFP) by following motor functions, striatal dopamine (HPLC and MRI-PET), and brain iron deposition (relaxation-R2*-MRI) aided by spectroscopic measurements of neuronal labile iron (with fluorescence-sensitive iron sensors) and oxidative damage by markers of protein, lipid, and DNA modification. DFP significantly reduced labile iron and biological damage in oxidation-stressed cells and animals, improving motor functions while raising striatal dopamine. For a pilot, double-blind, placebo-controlled randomized clinical trial, early-stage Parkinson's patients on stabilized dopamine regimens enrolled in a 12-month single-center study with DFP (30?mg/kg/day). Based on a 6-month DS paradigm, early-start patients (n=19) compared to DS patients (n=18) (37/40 completed) responded significantly earlier and sustainably to treatment in both substantia nigra iron deposits (R2* MRI) and Unified Parkinson's Disease Rating Scale motor indicators of disease progression (p<0.03 and p<0.04, respectively). Apart from three rapidly resolved neutropenia cases, safety was maintained throughout the trial. Innovation: A moderate iron chelation regimen that avoids changes in systemic iron levels may constitute a novel therapeutic modality for PD. Conclusions: The therapeutic features of a chelation modality established in translational models and in pilot clinical trials warrant comprehensive evaluation of symptomatic and/or disease-modifying potential of chelation in PD. Antioxid. Redox Signal. 21, 195–210. PMID:24251381

Moreau, Caroline; Devedjian, Jean Christophe; Kluza, Jerome; Petrault, Maud; Laloux, Charlotte; Jonneaux, Aurelie; Ryckewaert, Gilles; Garcon, Guillaume; Rouaix, Nathalie; Duhamel, Alain; Jissendi, Patrice; Dujardin, Kathy; Auger, Florent; Ravasi, Laura; Hopes, Lucie; Grolez, Guillaume; Firdaus, Wance; Sablonniere, Bernard; Strubi-Vuillaume, Isabelle; Zahr, Noel; Destee, Alain; Corvol, Jean-Christophe; Poltl, Dominik; Leist, Marcel; Rose, Christian; Defebvre, Luc; Marchetti, Philippe; Cabantchik, Z. Ioav; Bordet, Regis

2014-01-01

256

Flue gas desulfurization/denitrification using metal-chelate additives  

DOEpatents

A method of simultaneously removing SO.sub.2 and NO from oxygen-containing flue gases resulting from the combustion of carbonaceous material by contacting the flue gas with an aqueous scrubber solution containing an aqueous sulfur dioxide sorbent and an active metal chelating agent which promotes a reaction between dissolved SO.sub.2 and dissolved NO to form hydroxylamine N-sulfonates. The hydroxylamine sulfonates are then separated from the scrubber solution which is recycled.

Harkness, John B. L. (Naperville, IL); Doctor, Richard D. (Glen Ellyn, IL); Wingender, Ronald J. (Deerfield, IL)

1986-01-01

257

Removal of Trace Contaminants from Water Using New Chelating Resins  

Microsoft Academic Search

The modification of cross?linked polyacrylamide (CPAAm) and incorporation of methyl thiourea (MeTU) or phenyl thiourea (PhTU) group were utilized in the preparation of two new chelating resins CPAAm?EDA?MeTU (resin I) and CPAAM?EDA?PhTU (resin II), [EDA=ethylenediamine]. The prepared resins were characterized by elemental analysis and IR spectroscopy. The sorption behaviors of Cd(II), Pb(II), and Zn(II) ions on the prepared resins were

Mohammed A. Sharaf; Said A. Sayed; Ahmed A. Younis; A. B. Farag; Hassan A. Arida

2007-01-01

258

Chelate-Enhanced Phytoremediation of Soils Polluted with Heavy Metals  

Microsoft Academic Search

In general, hyperaccumulators are low biomass, slow-growing plants. High biomass non-hyperaccumulator plants by themselves are not a valid alternative for phytoextraction as they also have many limitations, such as small root uptake and little root-to-shoot translocation. In this context, chemically-induced phytoextraction (based on the fact that the application of certain chemicals, mostly chelating agents, to the soil significantly enhances metal

I. Alkorta; J. Hernández-Allica; J. M. Becerril; I. Amezaga; I. Albizu; M. Onaindia; C. Garbisu

2004-01-01

259

Flue gas desulfurization/denitrification using metal-chelate additives  

DOEpatents

A method of simultaneously removing SO/sub 2/ and NO from oxygen-containing flue gases resulting from the combustion of carbonaceous material by contacting the flue gas with an aqueous scrubber solution containing an aqueous sulfur dioxide sorbent and an active metal chelating agent which promotes a reaction between dissolved SO/sub 2/ and dissolved NO to form hydroxylamine N-sulfonates. The hydroxylamine sulfonates are then separated from the scrubber solution which is recycled. 3 figs.

Harkness, J.B.L.; Doctor, R.D.; Wingender, R.J.

1985-08-05

260

Phosphate compounds as iron chelators in animal cell cultures  

Microsoft Academic Search

Summary  We have studied the capacity of a number of phosphate compounds to act in the double role as a phosphate source and a detoxifier\\u000a of ferric chloride hydroxo compounds, i.e. as Fe(III) chelators. The tested compounds were: orthophosphate, trimetaphosphate,\\u000a ?-glycerophosphate, ?-glycerophosphate, phytic acid, and phosphorylcholine; the test organism the ciliate protozoonTetrahymena thermophila, an animal cell; and the nutrient medium was

Leif Rasmussen; Hans Toftlund

1986-01-01

261

Antibacterial and antibiofilm effects of iron chelators against Prevotella intermedia.  

PubMed

Prevotella intermedia, a major periodontopathogen, has been shown to be resistant to many antibiotics. In the present study, we examined the effect of the FDA-approved iron chelators deferoxamine (DFO) and deferasirox (DFRA) against planktonic and biofilm cells of P. intermedia in order to evaluate the possibility of using these iron chelators as alternative control agents against P. intermedia. DFRA showed strong antimicrobial activity (MIC and MBC values of 0.16 mg ml(-1)) against planktonic P. intermedia. At subMICs, DFRA partially inhibited the bacterial growth and considerably prolonged the bacterial doubling time. DFO was unable to completely inhibit the bacterial growth in the concentration range tested and was not bactericidal. Crystal violet binding assay for the assessment of biofilm formation by P. intermedia showed that DFRA significantly decreased the biofilm-forming activity as well as the biofilm formation, while DFO was less effective. DFRA was chosen for further study. In the ATP-bioluminescent assay, which reflects viable cell counts, subMICs of DFRA significantly decreased the bioactivity of biofilms in a concentration-dependent manner. Under the scanning electron microscope, P. intermedia cells in DFRA-treated biofilm were significantly elongated compared to those in untreated biofilm. Further experiments are necessary to show that iron chelators may be used as a therapeutic agent for periodontal disease. PMID:23329319

Moon, Ji-Hoi; Kim, Cheul; Lee, Hee-Su; Kim, Sung-Woon; Lee, Jin-Yong

2013-09-01

262

Prevention by chelating agents of metal-induced developmental toxicity.  

PubMed

Chelating agents such as calcium disodium ethylenediaminetetraacetate (EDTA), 2,3-dimercaptopropanol (BAL), or D-penicillamine (D-PA) have been widely used for the past 4 decades as antidotes for the treatment of acute and chronic metal poisoning. In recent years, meso-2,3-dimercaptosuccinic acid (DMSA), sodium 2,3-dimercapto-1-propanesulfonate (DMPS) and sodium 4,5-dihydroxybenzene-1,3-disulfonate (Tiron) have also shown to be effective to prevent against toxicity induced by a number of heavy metals. The purpose of the present article was to review the protective activity of various chelating agents against the embryotoxic and teratogenic effects of well-known developmental toxicants (arsenic, cadmium, lead, mercury, uranium, and vanadium). DMSA and DMPS were found to be effective in alleviating arsenate- and arsenite-induced teratogenesis, whereas BAL afforded only some protection against arsenic-induced embryo/fetal toxicity. Also, DMSA, DMPS, and Tiopronin were effective in ameliorating methyl mercury-induced developmental toxicity. Although the embryotoxic and teratogenic effects of vanadate were significantly reduced by Tiron, no significant amelioration of uranium-induced embryotoxicity was observed after treatment with this chelator. PMID:7795320

Domingo, J L

1995-01-01

263

Deferiprone, an orally deliverable iron chelator, ameliorates experimental autoimmune encephalomyelitis.  

PubMed

The iron chelator, Desferal, suppressed disease activity of experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis (MS), and it has been tested in pilot trials for MS. The administration regimen of Desferal is cumbersome and prone to complications. Orally-deliverable, iron chelators have been developed that circumvent these difficulties, and the objective of this study was to test an oral chelator in EAE. SJL mice with active EAE were randomly assigned to receive deferiprone (150 mg/kg) or vehicle (water) 2x/day via gavage. EAE mice given deferiprone had significantly less disease activity and lower levels of inflammatory cell infiltrates (revealed by H&E staining) than EAE mice administered vehicle. T-cell infiltration, assessed by anti-CD3 immunohistochemical staining, also was reduced, although not significantly. Splenocytes cultured from naïve SJL mice were stimulated with anti-CD3 and anti-CD28 with or without 250 microM deferiprone. While approximately 39% of costimulated splenocytes without deferiprone underwent division, only approximately 2.8% of costimulated splenocytes with deferiprone divided and the latter cells were only 53% as viable as the former. Deferiprone had no effect on proliferation or viability of cells that were not costimulated. In summary, deferiprone effectively suppressed active EAE disease and it inhibited T-cell function. PMID:17967839

Mitchell, K M; Dotson, A L; Cool, K M; Chakrabarty, A; Benedict, S H; LeVine, S M

2007-11-01

264

Mercury removal in utility wet scrubber using a chelating agent  

DOEpatents

A method for capturing and reducing the mercury content of an industrial flue gas such as that produced in the combustion of a fossil fuel or solid waste adds a chelating agent, such as ethylenediaminetetraacetic acid (EDTA) or other similar compounds like HEDTA, DTPA and/or NTA, to the flue gas being scrubbed in a wet scrubber used in the industrial process. The chelating agent prevents the reduction of oxidized mercury to elemental mercury, thereby increasing the mercury removal efficiency of the wet scrubber. Exemplary tests on inlet and outlet mercury concentration in an industrial flue gas were performed without and with EDTA addition. Without EDTA, mercury removal totaled 42%. With EDTA, mercury removal increased to 71%. The invention may be readily adapted to known wet scrubber systems and it specifically provides for the removal of unwanted mercury both by supplying S.sup.2- ions to convert Hg.sup.2+ ions into mercuric sulfide (HgS) and by supplying a chelating agent to sequester other ions, including but not limited to Fe.sup.2+ ions, which could otherwise induce the unwanted reduction of Hg.sup.2+ to the form, Hg.sup.0.

Amrhein, Gerald T. (Louisville, OH)

2001-01-01

265

Personalization of multiple sclerosis treatments: using the chelation therapy approach.  

PubMed

Though Multiple Sclerosis (MS) sufferers are probably genetically predisposed, toxic metal poisoning (TMP) does seem an increasingly likely environmental trigger. The technique for measuring and clearing TMP was chelation therapy using ethylene-diamine-tetracetic acid (EDTA), which revealed aluminum accumulation in both cases. The first patient, initially benefiting from removing dental fillings that had leaked mercury, also showed gadolinium accumulation from scan contrast medium, and a genomic deficiency of glutathione transferase M1. Glutathione production was impaired and hence also liver detoxification functions. The personal protocol involved glutathione administration and deutrosulfazyme to enhance oxygenation and alleviate oxidative stress. As aluminum began to clear with EDTA infusion, the extracellular/intracellular water ratio was carefully monitored, and carbohydrates limited. In the second case, aluminum poisoning responded to EDTA chelation therapy with eicosapentaenoic acid (EPA)/docosahexaenoic acid (DHA), multivitamins, and glutathione administration, again followed by deutrosulfazyme, water ratio control, and dietary correction. The two personalized protocols presented here tend to confirm the hypothesis of TMP as an environmental or iatrogenic trigger for MS, especially when inadequate detoxification lies at the root. Cleansing by chelation therapy, properly understood, can be efficacious, especially bearing in mind the altered cellular water ratio. PMID:23906103

Zanella, Sante Guido; Roberti di Sarsina, Paolo

2013-01-01

266

Chelation therapy in Wilson's disease: from D-penicillamine to the design of selective bioinspired intracellular Cu(I) chelators.  

PubMed

Wilson's disease is an orphan disease due to copper homeostasis dysfunction. Mutations of the ATP7B gene induces an impaired functioning of a Cu-ATPase, impaired Cu detoxification in the liver and copper overload in the body. Indeed, even though copper is an essential element, which is used as cofactor by many enzymes playing vital roles, it becomes toxic when in excess as it promotes cytotoxic reactions leading to oxidative stress. In this perspective, human copper homeostasis is first described in order to explain the mechanisms promoting copper overload in Wilson's disease. We will see that the liver is the main organ for copper distribution and detoxification in the body. Nowadays this disease is treated life-long by systemic chelation therapy, which is not satisfactory in many cases. Therefore the design of more selective and efficient drugs is of great interest. A strategy to design more specific chelators to treat localized copper accumulation in the liver will then be presented. In particular we will show how bioinorganic chemistry may help in the design of such novel chelators by taking inspiration from the biological copper cell transporters. PMID:22327203

Delangle, Pascale; Mintz, Elisabeth

2012-06-01

267

Depassivation of aged Fe0 by ferrous ions: implications to contaminant degradation.  

PubMed

Investigation of the effects of ferrous iron (Fe(II)) on the ability of aged (iron oxide coated) Fe(0) to degrade trichloroethylene (TCE) has revealed that, while neither aged Fe(0) nor Fe(II) separately were able to degrade TCE, approximately 95% of the TCE present was degraded after exposure to a mixture of aged Fe(0) and Fe(II) for 21 days. The rates of TCE degradation increased with an increase in Fe(II) concentration from 0 to 1.6 mM and then reached a relative plateau. Results of Fe(II) "adsorption" studies revealed that the equilibrium pH decreased significantly with an increase in Fe(II) concentration. Proton release during adsorption of Fe(II) to iron oxide coatings was identified as being responsible for promotion of surface dissolution and, concomitantly, enhancement in extent of TCE reduction by aged Fe(0). Results of open circuit potential analysis and Tafel plot measurement showed that the corrosion potential of aged Fe(0) (E(corr)) in the presence of Fe(II) decreased to levels similar to that of Fe(0)/Fe(2+), while significant increase in corrosion current (I(corr)) and decrease in polarization resistance (Rp) were found with an increase in Fe(II) concentration. The fact that the effects of different Fe(II) concentrations on the E(corr), I(corr), and Rp was decoupled from their effects on TCE degradation by aged Fe(0) suggested that the enhancement of TCE degradation in the presence of Fe(II) was attributable to the dissolution of the Fe(III) oxyhydroxide layer coating the aged Fe(0). While the presence of Fe(II) may also lead to transformation of the Fe(III) (oxy)hydroxide coating to more crystalline phases, the rate of reduction of compounds such as TCE by Fe(II) associated with the Fe(III) (oxy)hydroxide coating is substantially slower than that mediated by Fe(0). These findings provide new insight into the molecular-scale interaction of aged Fe(0) and ferrous iron with particular implications for sustaining the reactivity of Fe(0)-mediated degradation of contaminants in iron-bearing environments. PMID:24195471

Liu, Tongxu; Li, Xiaomin; Waite, T David

2013-12-01

268

Determining Oxygen Isotopic Fractionation between the ferrous sulfate, melanterite, and aqueous sulfate  

NASA Astrophysics Data System (ADS)

Studying regions on Earth that are analogous to Mars serve as case studies for studying astrobiology and planetary surface rock formation processes. Rio Tinto, Spain is very rich in iron sulfates, and has an environment that is possibly very similar to the former environment on Mars. Certain bacteria play significant roles in accelerating pyrite oxidation rates, the products of which contribute to the formation of ferrous sulfates, such as melanterite. During mineral crystallization in an aqueous solution, there are systematic isotopic differences between dissolved species and solid phases. Quantifying this fractionation enables isotopic analysis to be used to trace the original isotopic signature of the dissolved species. Isotope fractionation has been determined for minerals such as gypsum and epsomite, and from these results and theoretical predictions, it is expected that melanterite, a mineral potentially found on Mars, would be more enriched in oxygen-18 relative to the aqueous solution from which it crystallized.Thus, determining the oxygen-18 isotopic fractionation between melanterite and dissolved sulfate has many potential benefits for understanding surface processes on Mars and its past environment. To investigate the oxygen isotope fractionation for melanterite, acidic aqueous solutions saturated with dissolved hydrated ferrous sulfate were evaporated at 25 deg C and 40 deg C and under different conditions to induce different evaporation rates. During evaporation, the aqueous solution and crystallized melanterite were sampled at different stages. Oxygen-18 isotopic compositions were then measured. However, the fractionations observed in the experiments were opposite from predictions. At 25 deg C without enhanced evaporation, the dissolved sulfate was +5.5 per mil relative to the solid, while at 40 deg C it was +4.3 per mil. With enhanced evaporation, fractionation was +2.1 per mil, while at 40 deg C it was +3.6 per mil. In addition, at 40 deg C, evaporation rates and fractionation were larger than at 25 deg C. Because no Rayleigh fractionation was observed, this system was not in equilibrium, and was most likely dominated by kinetics. Because of the unexpected results, further research will be conducted on the oxygen isotope fractionation of melanterite.

Shulaker, D. Z.; Kohl, I.; Coleman, M. L.

2011-12-01

269

Prevention and treatment of aluminum toxicity including chelation therapy: status and research needs.  

PubMed

The prevention and treatment of aluminum (Al) accumulation and toxicity are reviewed. Recommendations to further our understanding of desferrioxamine (deferoxamine, DFO) treatment and to develop more effective chelation approaches are provided. Reduction of Al accumulation and toxicity may benefit end-stage renal disease (ESRD) patients and perhaps those suffering from specific neurodegenerative disorders as well as workers with Al-induced neurocognitive disorders. The clearance of Al may be increased by extracorporeal chelation, renal transplantation, perhaps complexation with simple ligands such as silicon (Si), and systemic chelation therapy. The abilities of extracorporeal chelation and Si to reduce Al accumulation require further evaluation. Although it may not be possible to design Al-specific chelators, chelators with greater Al selectivity are desired. Aluminum-selective chelation might be achieved by targeted chelator distribution or by the use of adjuvants with the chelator. The ability of carboxylic acids to facilitate Al elimination, under specific conditions, warrants further study. Desferrioxamine does not produce significant biliary Al excretion. A chelator with this property may be useful in ESRD patients. The necessity for an Al chelator to distribute extravascularly to be effective is unknown and should be determined to guide the selection of alternatives to DFO. The lack of oral efficacy and occasional side effects of DFO encourage identification of orally effective, safer Al chelators. The bidentate 3-hydroxypyridin-4-ones are currently the most encouraging alternatives to DFO. They have been shown to increase urinary Al excretion in rats and rabbits, but to have toxicity comparable to, or greater than, DFO. Their toxicity may relate to incomplete metal complexation. The ability of orally effective chelators to increase absorption of chelated metal from the gastrointestinal (Gl) tract needs to be evaluated. Orally effective, safe Al chelators would be of benefit to peritoneal dialysis patients and those with neurodegenerative disorders, if Al chelation therapy is indicated. The reduction of Alzheimer's disease (AD) progression and the reversal of Al-induced behavioral deficits and neurofibrillary tangles by DFO encourage further study of Al chelation therapy for selected neurodegenerative disorders. PMID:8772805

Yokel, R A; Ackrill, P; Burgess, E; Day, J P; Domingo, J L; Flaten, T P; Savory, J

1996-08-30

270

Synergistic De-colorization of CanLan-Green Solution with Attapulgite-Ferrous Sulfate Composite Coagulator  

NASA Astrophysics Data System (ADS)

Attapulgite clay has strong adsorptive ability, excellent chemical stability and biological safety, thus has attracted more and more attention in application for environmental field recently. In this study, 0.01 g/L Canlan-Green solution was prepared as treatment target, and the optimal preparation conditions of attapulgite-ferrous sulfate composite coagulator were obtained by methods of heat pretreatment, high temperature calcination and orthogonal experiments; Then the best dosage of composite coagulator for de-colorization of CanLan-Green solution was determined via inspecting factors as pH, reaction temperature, settlement time, reaction time, agitation rate etc. Compared with conventional coagulator ferrous sulfate, composite coagulator possesses advantages of less dosage, excellent decolorization performance, speediness, better settlement ability, cheaper and safer and so on. It proves to be an ideal inorganic composite coagulator choice.

Han, Hong; Gu, Xu; Li, Dong; Zhou, Sumin; Jiang, Saibo; Lu, Humei

2010-11-01

271

Leaching of zinc sulfide by Thiobacillus ferrooxidans: bacterial oxidation of the sulfur product layer increases the rate of zinc sulfide dissolution at high concentrations of ferrous ions.  

PubMed

This paper reports the results of leaching experiments conducted with and without Thiobacillus ferrooxidans at the same conditions in solution. The extent of leaching of ZnS with bacteria is significantly higher than that without bacteria at high concentrations of ferrous ions. A porous layer of elemental sulfur is present on the surfaces of the chemically leached particles, while no sulfur is present on the surfaces of the bacterially leached particles. The analysis of the data using the shrinking-core model shows that the chemical leaching of ZnS is limited by the diffusion of ferrous ions through the sulfur product layer at high concentrations of ferrous ions. The analysis of the data shows that diffusion through the product layer does not limit the rate of dissolution when bacteria are present. This suggests that the action of T. ferrooxidans in oxidizing the sulfur formed on the particle surface is to remove the barrier to diffusion by ferrous ions. PMID:10583978

Fowler, T A; Crundwell, F K

1999-12-01

272

Novel electrochemical-enzymatic model which quantifies the effect of the solution Eh on the kinetics of ferrous iron oxidation with Acidithiobacillus ferrooxidans.  

PubMed

The influence of solution Eh on the rate of ferrous iron oxidation by Acidithiobacillus ferrooxidans is characterized. The experimental approach was based on the use of a two-chamber bioelectrochemical cell, which can determine the ferrous iron oxidation rate at controlled potential. Results enabled the formulation of a novel kinetic model, which incorporates the effect of solution Eh in an explicit form but still integrates the effect of ferrous iron concentration and ferric inhibition. The results showed that at Eh values below 650 mV (standard hydrogen electrode, SHE) the bacterial oxidative activity is mainly dependent on ferrous iron concentration. At Eh values between 650 and 820 mV (SHE) the oxidation rate is mainly controlled by ferric inhibition. Over 820 mV (SHE) the bacterial oxidative activity is strongly inhibited by the Eh increase, being completely inhibited at Eh = 840 mV (SHE). PMID:12226860

Meruane, G; Salhe, C; Wiertz, J; Vargas, T

2002-11-01

273

Application research of ferrous matrix composites in roller ring used in high-speed wire\\/bar rolling mill  

Microsoft Academic Search

Tungsten carbide particle (WCP) reinforced ferrous matrix composites roller rings were fabricated by centrifugal casting. The microstructures, properties and application effect of the composites roller rings were investigated by SEM, TEM and various property testers. The experimental results show that the WCP were uniformly distributed in outer reinforced-layer (working-layer) of 20–50mm in thickness and their volume fraction reached 60–80vol.%; there

Yanpei Song; Xiuqing Li; Shuangxu Bi

2010-01-01

274

Novel atmospheric scorodite synthesis by oxidation of ferrous sulfate solution. Part II. Effect of temperature and air  

Microsoft Academic Search

We have previously reported a novel method for producing stable scorodite (FeAsO4·2H2O) under atmospheric conditions in which ferrous sulfate was oxidized by oxygen in the presence of high concentrations of arsenic(V). This work examines the effects of reaction temperature (95, 70, 50 °C) and the oxidizing agent (air, pure oxygen gas) to optimize scorodite formation in a practical process. Crystalline scorodite

T. Fujita; R. Taguchi; M. Abumiya; M. Matsumoto; E. Shibata; T. Nakamura

2008-01-01

275

Isotopic characterisation of lead in contaminated soils from the vicinity of a non-ferrous metal smelter near Plovdiv, Bulgaria  

Microsoft Academic Search

Soil samples from the vicinity of a non-ferrous metal smelter near Plovdiv, Bulgaria contained very high concentrations of cadmium, lead and zinc (up to 140, 4900 and 5900mgkg?1, respectively). A roadside soil in a relatively uncontaminated area also contained high concentrations of the same metals (24, 1550 and 1870mgkg?1, respectively) indicating that the transport of ores could be a source

Jeffrey R. Bacon; Nikolai S. Dinev

2005-01-01

276

Alginate Inhibits Iron Absorption from Ferrous Gluconate in a Randomized Controlled Trial and Reduces Iron Uptake into Caco-2 Cells  

PubMed Central

Previous in vitro results indicated that alginate beads might be a useful vehicle for food iron fortification. A human study was undertaken to test the hypothesis that alginate enhances iron absorption. A randomised, single blinded, cross-over trial was carried out in which iron absorption was measured from serum iron appearance after a test meal. Overnight-fasted volunteers (n?=?15) were given a test meal of 200 g cola-flavoured jelly plus 21 mg iron as ferrous gluconate, either in alginate beads mixed into the jelly or in a capsule. Iron absorption was lower from the alginate beads than from ferrous gluconate (8.5% and 12.6% respectively, p?=?0.003). Sub-group B (n?=?9) consumed the test meals together with 600 mg calcium to determine whether alginate modified the inhibitory effect of calcium. Calcium reduced iron absorption from ferrous gluconate by 51%, from 11.5% to 5.6% (p?=?0.014), and from alginate beads by 37%, from 8.3% to 5.2% (p?=?0.009). In vitro studies using Caco-2 cells were designed to explore the reasons for the difference between the previous in vitro findings and the human study; confirmed the inhibitory effect of alginate. Beads similar to those used in the human study were subjected to simulated gastrointestinal digestion, with and without cola jelly, and the digestate applied to Caco-2 cells. Both alginate and cola jelly significantly reduced iron uptake into the cells, by 34% (p?=?0.009) and 35% (p?=?0.003) respectively. The combination of cola jelly and calcium produced a very low ferritin response, 16.5% (p<0.001) of that observed with ferrous gluconate alone. The results of these studies demonstrate that alginate beads are not a useful delivery system for soluble salts of iron for the purpose of food fortification. Trial Registration ClinicalTrials.gov NCT01528644 PMID:25391138

Wawer, Anna A.; Harvey, Linda J.; Dainty, Jack R.; Perez-Moral, Natalia; Sharp, Paul; Fairweather-Tait, Susan J.

2014-01-01

277

Effects of Fetal Bovine Serum on Ferrous IonInduced Oxidative Stress in Pheochromocytoma (PC12) Cells  

Microsoft Academic Search

Ferrous ion (Fe2+) has been considered to be a cause of neuronal oxidative injury. Since body fluids contain protein and serum is an essential component of tissue culture medium, we have examined the role of serum protein on Fe2+-mediated oxidative stress using PC12 cells and rat cerebral cortices. Fe2+ or the combination of ascorbate and Fe2+ increased concentrations of thiobarbituric

Jin H. Song; Michael S. Harris; Seon H. Shin

2001-01-01

278

Identification of active agents for tetrachloroethylene degradation in Portland cement slurry containing ferrous iron.  

PubMed

Experimental studies were designed to identify the active agents in Fe(II)-based degradative solidification/stabilization (Fe(II)-DS/S) that are responsible for the degradation of tetrachloroethylene (PCE) as well as the conditions that enhance the formation of these active agents. First, the conditions that lead to maximizing production of the active agents were identified by measuring the ability of various chemical mixtures to degrade PCE. Results showed that Fe(II), Fe(III), and Cl were the elements most closely associated with high degradation rates. In addition to elemental composition, unknown factors associated with the formation of solid phases could also be important in determining the extent of formation of active reducing agents. Second, instrumental analysis techniques (XRD, SEM, SEM-EDS) were used to identify compounds in chemical mixtures that were observed to have high activities for PCE degradation. SEM-EDS analysis indicated that Fe was associated with hexagonal particles, which is the typical shape of several AFm phases in hydrated Portland cement that are composed of calcium, aluminum/iron, hydroxide, and possibly other anions. No Fe-containing solid phases could be identified. Therefore, it appears that AFm phases are the most likely active agents for PCE degradation in mixtures containing Portland cement or its acid extract. Mixtures without cement did not form the same solid phases but were observed to form ferrous hydroxide as a major solid phase. PMID:17874793

Ko, Saebom; Batchelor, Bill

2007-08-15

279

First-principles study of intermediate-spin ferrous iron in the Earth's lower mantle  

E-print Network

Spin crossover of iron is of central importance in solid Earth geophysics. It impacts all physical properties of minerals that altogether constitute $\\sim 95$ vol\\% of the Earth's lower mantle: ferropericlase [(Mg,Fe)O] and Fe-bearing magnesium silicate (MgSiO$_3$) perovskite. Despite great strides made in the past decade, the existence of intermediate-spin (IS) state in ferrous iron (Fe$^{2+}$) (with total electron spin $S=1$) and its possible role in the pressure-induced spin crossover in these lower-mantle minerals still remain controversial. Using density functional theory $+$ self-consistent Hubbard $U$ (DFT$+U_{sc}$) calculations, we investigate all possible types of IS states of Fe$^{2+}$ in (Mg,Fe)O and (Mg,Fe)SiO$_3$ perovskite. Among the possible IS states in these minerals, the most probable IS state has an electronic configuration that significantly reduces the electron overlap and the iron nuclear quadrupole splitting (QS). These most probable IS states, however, are still energetically disfavore...

Hsu, Han

2014-01-01

280

Ferrous iron uptake by Bifidobacterium bifidum var. pennsylvanicus: the effect of metals and metabolic inhibitors.  

PubMed

Ferrous iron uptake studies in Bifidobacterium bifidum var. pennsylvanicus were carried out in a well-defined salt solution termed "modified Hanks solution" at both high iron concentrations (LAFIUS conditions) and low concentrations (HAFIUS conditions). Various divalent metals, Mn2+, Zn2+, Ni2+ and Cu2+, inhibited iron uptake under HAFIUS conditions in a non-competitive manner, and in a pseudo-competitive manner under LAFIUS conditions. Cr2+ had no effect. Co2+ inhibited iron uptake competitively under HAFIUS conditions. Metabolic affectors that inhibited iron uptake both under HAFIUS and LAFIUS conditions were: tetraphenylphosphonium chloride, diethylstilbesterol, vanadate, carbonylcyanide-m-chlorophenyl-hydrazone, and a mixture of valinomycin and nigericin. Substances that stimulated iron uptake were KCl, valinomycin, and nigericin. Iron uptake under LAFIUS conditions in piperazine-buffered modified Hanks solution was higher than that in the acetate-buffered solution, and acetate inhibited iron uptake in the piperazine buffer. HAFIUS showed no difference. It is concluded that iron uptake in bifidobacteria is driven by an ATPase-dependent proton-motive force and that both the pH gradient and membrane potential are involved in this process. Mn2+, Zn2+, Ni2+, and Cu2+ may be transported via LAFIUS, but not HAFIUS. HAFIUS may transport only Co2+ in addition to Fe2+. PMID:3038634

Bezkorovainy, A; Solberg, L; Poch, M; Miller-Catchpole, R

1987-01-01

281

Lung cancer in a non-ferrous smelter: the role of cadmium.  

PubMed Central

Lung cancer mortality was examined in a cohort of 4393 men employed at a zinc-lead-cadmium smelter. There was an excess of lung cancer (overall SMR = 124.5, 95% confidence interval 107-144) which was particularly evident for those employed for more than 20 years. A statistically significant trend in SMRs with increasing duration of employment was apparent. Quantitative estimates of exposure to cadmium and ordinal rankings for lead, arsenic, zinc, sulphur dioxide, and dust were used to calculate cumulative exposures from job histories. Matched logistic regression was used to compare the cumulative exposures of cases of lung cancer to those of controls matched for date of birth and date of starting work and surviving at the time of death of the matched cases. The increasing risk of lung cancer associated with increasing duration of employment could not be accounted for by cadmium and did not appear to be restricted to any particular process or department. Although lung cancer mortality was associated with estimates of cumulative exposure to arsenic and to lead, it was not possible to determine whether the increased risk might be due to arsenic, lead, or to other contaminants in the smelter. These results are compared with findings from other non-ferrous smelters. PMID:3395580

Ades, A E; Kazantzis, G

1988-01-01

282

THE THERMAL DECOMPOSITION OF THE 5,7-DIHALO-8QUINOLINOL RARE EARTH METAL CHELATES  

Microsoft Academic Search

S>The thermal decomposition of the 5,7-dichloro-, 5,7dibromo- and 5,7-; diiodo-8-quinolinol chelates of La, Ce, Pr, Nd, Sm, and Y was investigated on the ; thermobalance. The chelates decomposed in the temperature range from 65 to 125 ; deg C while the oxide levels were obtained from 395 to 805 deg C. Although the ; chelate thermal stability temperatures varied little

W Wendlandt

1957-01-01

283

Validation of the spectrophotometric determination of omeprazole and pantoprazole sodium via their metal chelates  

Microsoft Academic Search

Spectrophotometric procedures for the determination of two irriversible proton pump inhibitors, omeprazole (OMZ) and pantoprazole (PNZ) sodium have been developed, the procedures are based on the formation of 2:1 chelates of both drugs with different metal ions. Pantoprazole sodium is quantified by a stability-indicating procedure through chelation with iron (III) in aqueous-ethanol medium to form an orange chelate picked at

F Salama; N El-Abasawy; S. A Abdel Razeq; M. M. F Ismail; M. M Fouad

2003-01-01

284

Azide, cyanide, fluoride, imidazole and pyridine binding to ferric and ferrous native horse heart cytochrome c and to its carboxymethylated derivative: A comparative study  

Microsoft Academic Search

Azide, cyanide, fluoride, imidazole, and pyridine binding to ferric and ferrous native horse heart cytochrome c and to its carboxymethylated derivative has been investigated, from the thermodynamic viewpoint, at pH 7.5 and 25.0°C. Ligand affinity for ferric and ferrous carboxymethylated cytochrome c is higher by about 30- and 400-fold, respectively, than that observed for the native protein. The results here

Franca Viola; Silvio Aime; Massimo Coletta; Alessandro Desideri; Mauro Fasano; Silvia Paoletti; Cataldo Tarricone; Paolo Ascenzi

1996-01-01

285

Advances in transient (pulsed) eddy current for inspection of multi-layer aluminum structures in the presence of ferrous fasteners  

NASA Astrophysics Data System (ADS)

An experimental investigation of the electromagnetic processes underlying transient (pulsed) eddy current inspection of aircraft wing structures in the vicinity of ferrous fasteners is performed. The separate effects of transient excitation of ferrous fastener and eddy currents induced in the surrounding aluminum structure are explored using a transmit-receive configuration with transient excitation of a steel rod, an aluminum plate with a bore hole and a steel rod through the bore hole. Observations are used to interpret results from a coupled driving and differential coil sensing unit applied to detect fatigue cracks emanating from bolt holes in aluminum structures with ferrous fasteners present. In particular, it is noted that abrupt magnetization of the fastener, by the probe's central driving unit, can transfer flux and consequently, induce strong eddy current responses deep within the aluminum structure in the vicinity of the bore hole. Rotation of the probe, centered over the fastener, permits detection of subsurface discontinuities, such as cracks, by the pair of differentially connected pickup coils.

Desjardins, D. R.; Vallières, G.; Whalen, P. P.; Krause, T. W.

2012-05-01

286

Zinc chelation reduces hippocampal neurogenesis after pilocarpine-induced seizure.  

PubMed

Several studies have shown that epileptic seizures increase hippocampal neurogenesis in the adult. However, the mechanism underlying increased neurogenesis after seizures remains largely unknown. Neurogenesis occurs in the subgranular zone (SGZ) of the hippocampus in the adult brain, although an understanding of why it actively occurs in this region has remained elusive. A high level of vesicular zinc is localized in the presynaptic terminals of the SGZ. Previously, we demonstrated that a possible correlation may exist between synaptic zinc localization and high rates of neurogenesis in this area after hypoglycemia. Using a lithium-pilocarpine model, we tested our hypothesis that zinc plays a key role in modulating hippocampal neurogenesis after seizure. Then, we injected the zinc chelator, clioquinol (CQ, 30 mg/kg), into the intraperitoneal space to reduce brain zinc availability. Neuronal death was detected with Fluoro Jade-B and NeuN staining to determine whether CQ has neuroprotective effects after seizure. The total number of degenerating and live neurons was similar in vehicle and in CQ treated rats at 1 week after seizure. Neurogenesis was evaluated using BrdU, Ki67 and doublecortin (DCX) immunostaining 1 week after seizure. The number of BrdU, Ki67 and DCX positive cell was increased after seizure. However, the number of BrdU, Ki67 and DCX positive cells was significantly decreased by CQ treatment. Intracellular zinc chelator, N,N,N0,N-Tetrakis (2-pyridylmethyl) ethylenediamine (TPEN), also reduced seizure-induced neurogenesis in the hippocampus. The present study shows that zinc chelation does not prevent neurodegeneration but does reduce seizure-induced progenitor cell proliferation and neurogenesis. Therefore, this study suggests that zinc has an essential role for modulating hippocampal neurogenesis after seizure. PMID:23119054

Kim, Jin Hee; Jang, Bong Geom; Choi, Bo Young; Kwon, Lyo Min; Sohn, Min; Song, Hong Ki; Suh, Sang Won

2012-01-01

287

Chelate Assisted, Pressurized, Liquid Extraction for the Removal of Adsorbed Metal Contaminants From Soils.  

E-print Network

??Chelate Assisted, Pressurized, Liquid Extraction (CAPLE) has been developed in our laboratory as an efficient, separation-based, extraction methodology for heavy metals in soils. Unlike current… (more)

Marshall, Karen L.

2000-01-01

288

Chelation and determination of labile iron in primary hepatocytes by pyridinone fluorescent probes  

PubMed Central

A series of fluorescent iron chelators has been synthesized such that a fluorescent function is covalently linked to a 3-hydroxypyridin-4-one. In the present study, the fluorescent iron chelators were loaded into isolated rat hepatocytes. The intracellular fluorescence was not only quenched by an addition of a highly lipophilic 8-hydroxyquinoline–iron(III) complex but also was dequenched by the addition of an excess of the membrane-permeable iron chelator CP94 (1,2-diethyl-3-hydroxypyridin-4-one). The time course of uptake of iron and iron chelation in single, intact cells was recorded on-line by using digital fluorescence microscopy. Intracellular concentrations of various fluorescent iron chelators were determined by using a spectrofluorophotometer subsequent to lysis of probe-loaded cells and were found to depend on their partition coefficients; the more hydrophobic the compound, the higher the intracellular concentration. An ex situ calibration method was used to determine the chelatable iron pool of cultured rat hepatocytes. CP655 (7-diethylamino-N-[(5-hydroxy-6-methyl-4-oxo-1,4-dihydropyridin-3-yl)methyl]-N-methyl-2-oxo-2H-chromen-3-carboxamide), which is a moderately lipophilic fluorescent chelator, was found to be the most sensitive probe for monitoring chelatable iron, as determined by the intracellular fluorescence increase induced by the addition of CP94. The concentration of the intracellular chelatable iron pool in hepatocytes was determined by this probe to be 5.4±1.3 ?M. PMID:16336208

Ma, Yongmin; de Groot, Herbert; Liu, Zudong; Hider, Robert C.; Petrat, Frank

2005-01-01

289

Efficacy, Tolerability, and Acceptability of Iron Hydroxide Polymaltose Complex versus Ferrous Sulfate: A Randomized Trial in Pediatric Patients with Iron Deficiency Anemia  

PubMed Central

Iron polymaltose complex (IPC) offers similar efficacy with superior tolerability to ferrous sulfate in adults, but randomized trials in children are rare. In a prospective, open-label, 4-month study, 103 children aged >6 months with iron deficiency anemia (IDA) were randomized to IPC once daily or ferrous sulfate twice daily, (both 5?mg iron/kg/day). Mean increases in Hb to months 1 and 4 with IPC were 1.2 ± 0.9?g/dL and 2.3 ± 1.3?g/dL, respectively, (both P = 0.001 versus baseline) and 1.8 ± 1.7?g/dL and 3.0 ± 2.3?g/dL with ferrous sulfate (both P = 0.001 versus baseline) (n.s. between groups). Gastrointestinal adverse events occurred in 26.9% and 50.9% of IPC and ferrous sulfate patients, respectively (P = 0.012). Mean acceptability score at month 4 was superior with IPC versus ferrous sulfate (1.63 ± 0.56 versus 2.14 ± 0.75, P = 0.001). Efficacy was comparable with IPC and ferrous sulfate over a four-month period in children with IDA, but IPC was associated with fewer gastrointestinal adverse events and better treatment acceptability. PMID:22121379

Yasa, Beril; Agaoglu, Leyla; Unuvar, Emin

2011-01-01

290

Chelate-modified polymers for atmospheric gas chromatography  

NASA Technical Reports Server (NTRS)

Chromatographic materials were developed to serve as the stationary phase of columns used in the separation of atmospheric gases. These materials consist of a crosslinked porous polymer matrix, e.g., a divinylbenzene polymer, into which has been embedded an inorganic complexed ion such as N,N'-ethylene-bis-(acetylacetoniminato)-cobalt (2). Organic nitrogenous bases, such as pyridine, may be incorporated into the chelate polymer complexes to increase their chromatographic utility. With such materials, the process of gas chromatography is greatly simplified, especially in terms of time and quantity of material needed for a gas separation.

Christensen, W. W.; Mayer, L. A.; Woeller, F. H. (inventors)

1980-01-01

291

Mesoporous organosilica nanotubes containing a chelating ligand in their walls  

NASA Astrophysics Data System (ADS)

We report the synthesis of organosilica nanotubes containing 2,2'-bipyridine chelating ligands within their walls, employing a single-micelle-templating method. These nanotubes have an average pore diameter of 7.8 nm and lengths of several hundred nanometers. UV-vis absorption spectra and scanning transmission electron microscopy observations of immobilized nanotubes with an iridium complex on the bipyridine ligands showed that the 2,2'-bipyridine groups were homogeneously distributed in the benzene-silica walls. The iridium complex, thus, immobilized on the nanotubes exhibited efficient catalytic activity for water oxidation using Ce4+, due to the ready access of reactants to the active sites in the nanotubes.

Liu, Xiao; Goto, Yasutomo; Maegawa, Yoshifumi; Ohsuna, Tetsu; Inagaki, Shinji

2014-11-01

292

Chelating polymers for recovery of uranium from seawater  

SciTech Connect

Despite the low concentration of uranium in seawater (3.3 ppb), a special emphasis has been placed on its recovery. Although the concentration is low, it has been estimated that the world's oceans contain about 4 x 10[sup 9] tons of uranium - theoretically an unlimited supply of nuclear fuel. Adsorption has been considered to be a technically feasible procedure for a uranium recovery process with regard to economic and environmental impacts. The present paper restricts its coverage to those applications using chelating polymeric resins containing amidoxime groups as the most promising adsorbent. 72 refs., 8 figs., 1 tab.

Kabay, N. (Ege Univ., Izmir (Turkey)); Egawa, Hiroaki (Kumamoto Univ. (Japan))

1994-01-01

293

Human studies with the chelating agents, DMPS and DMSA.  

PubMed

Meso-2,3-dimercaptosuccinic acid (DMSA) is bound to plasma albumin in humans and appears to be excreted in the urine as the DMSA-cysteine mixed disulfide. The pharmacokinetics of DMSA have been determined after its administration to humans po. For the blood, the tmax and t1/2 were 3.0 h + 0.45 SE and 3.2 h + 0.56 SE, respectively. The Cmax was 26.2 microM + 4.7 SE. To determine whether dental amalgams influence the human body burden of mercury, we gave volunteers the sodium salt of 2,3-dimercaptopropane-1-sulfonic acid (DMPS). The diameters of dental amalgams of the subjects were determined to obtain the amalgam score. Administration of 300 mg DMPS by mouth increased the mean urinary mercury excretion of subjects over a 9 h period. There was a positive correlation between the amount of mercury excreted and the amalgam score. DMPS might be useful for increasing the urinary excretion of mercury and thus increasing the significance and reliability of this measure of mercury exposure. DMSA analogs have been designed and synthesized in attempts to increase the uptake by cell membranes of the DMSA prototype chelating agents. The i.v. administration of the monomethyl ester of DMSA, the dimethyl ester of DMSA or the zinc chelate of dimethyl DMSA increases the biliary excretion of platinum and cadmium in rats. PMID:1331491

Aposhian, H V; Maiorino, R M; Rivera, M; Bruce, D C; Dart, R C; Hurlbut, K M; Levine, D J; Zheng, W; Fernando, Q; Carter, D

1992-01-01

294

Iron chelation: a potential therapeutic strategy in oesophageal cancer  

PubMed Central

Raised intracellular iron has been identified as a potential aetiological factor in the development of several epithelial malignancies, including those of the gastrointestinal tract. The mechanism behind this increase is thought to include disorders of iron uptake and storage. Several iron chelators have been identified as potential anti-tumour agents, with much work undertaken to ascertain the exact mode of action. Despite this, there is little known about the role that these drugs play in the cellular iron metabolism of oesophageal cancer. Consequently, the present study looks to review the relationship of two clinically important iron-chelating agents, deferoxamine and deferasirox, on cellular iron uptake and storage in oesophageal squamous and adenocarcinoma. This provides important evidence for the debate about the role these agents have in the clinical management of such tumours. Linked Article This article is a commentary on Ford et al., pp. 1316–1328 of this issue. To view this paper visit http://dx.doi.org/10.1111/bph.12045 PMID:23278384

Keeler, BD; Brookes, MJ

2013-01-01

295

Chelators in the Treatment of Iron Accumulation in Parkinson's Disease  

PubMed Central

Iron is an essential element in the metabolism of all cells. Elevated levels of the metal have been found in the brains of patients of numerous neurodegenerative disorders, including Parkinson's disease (PD). The pathogenesis of PD is largely unknown, although it is thought through studies with experimental models that oxidative stress and dysfunction of brain iron homeostasis, usually a tightly regulated process, play significant roles in the death of dopaminergic neurons. Accumulation of iron is present at affected neurons and associated microglia in the substantia nigra of PD patients. This additional free-iron has the capacity to generate reactive oxygen species, promote the aggregation of ?-synuclein protein, and exacerbate or even cause neurodegeneration. There are various treatments aimed at reversing this pathologic increase in iron content, comprising both synthetic and natural iron chelators. These include established drugs, which have been used to treat other disorders related to iron accumulation. This paper will discuss how iron dysregulation occurs and the link between increased iron and oxidative stress in PD, including the mechanism by which these processes lead to cell death, before assessing the current pharmacotherapies aimed at restoring normal iron redox and new chelation strategies undergoing research. PMID:22754573

Mounsey, Ross B.; Teismann, Peter

2012-01-01

296

Copper chelation represses the vascular response to injury  

PubMed Central

The induction of an acute inflammatory response followed by the release of polypeptide cytokines and growth factors from peripheral blood monocytes has been implicated in mediating the response to vascular injury. Because the Cu2+-binding proteins IL-1? and fibroblast growth factor 1 are exported into the extracellular compartment in a stress-dependent manner by using intracellular Cu2+ to facilitate the formation of S100A13 heterotetrameric complexes and these signal peptideless polypeptides have been implicated as regulators of vascular injury in vivo, we examined the ability of Cu2+ chelation to repress neointimal thickening in response to injury. We observed that the oral administration of the Cu2+ chelator tetrathiomolybdate was able to reduce neointimal thickening after balloon injury in the rat. Interestingly, although immunohistochemical analysis of control neointimal sections exhibited prominent staining for MAC1, IL-1?, S100A13, and the acidic phospholipid phosphatidylserine, similar sections obtained from tetrathiomolybdate-treated animals did not. Further, adenoviral gene transfer of the IL-1 receptor antagonist during vascular injury also significantly reduced the area of neointimal thickening. Our data suggest that intracellular copper may be involved in mediating the response to injury in vivo by its ability to regulate the stress-induced release of IL-1? by using the nonclassical export mechanism employed by human peripheral blood mononuclear cells in vitro. PMID:12754378

Mandinov, Lazar; Mandinova, Anna; Kyurkchiev, Stanimir; Kyurkchiev, Dobroslav; Kehayov, Ivan; Kolev, Vihren; Soldi, Raffaella; Bagala, Cinzia; de Muinck, Ebo D.; Lindner, Volkhard; Post, Mark J.; Simons, Michael; Bellum, Stephen; Prudovsky, Igor; Maciag, Thomas

2003-01-01

297

Branched polymeric media: boron-chelating resins from hyperbranched polyethylenimine.  

PubMed

Extraction of boron from aqueous solutions using selective resins is important in a variety of applications including desalination, ultrapure water production, and nuclear power generation. Today's commercial boron-selective resins are exclusively prepared by functionalization of styrene-divinylbenzene (STY-DVB) beads with N-methylglucamine to produce resins with boron-chelating groups. However, such boron-selective resins have a limited binding capacity with a maximum free base content of 0.7 eq/L, which corresponds to a sorption capacity of 1.16 ± 0.03 mMol/g in aqueous solutions with equilibrium boron concentration of ?70 mM. In this article, we describe the synthesis and characterization of a new resin that can selectively extract boron from aqueous solutions. We show that branched polyethylenimine (PEI) beads obtained from an inverse suspension process can be reacted with glucono-1,5-D-lactone to afford a resin consisting of spherical beads with high density of boron-chelating groups. This resin has a sorption capacity of 1.93 ± 0.04 mMol/g in aqueous solution with equilibrium boron concentration of ?70 mM, which is 66% percent larger than that of standard commercial STY-DVB resins. Our new boron-selective resin also shows excellent regeneration efficiency using a standard acid wash with a 1.0 M HCl solution followed by neutralization with a 0.1 M NaOH solution. PMID:22827255

Mishra, Himanshu; Yu, Changjun; Chen, Dennis P; Goddard, William A; Dalleska, Nathan F; Hoffmann, Michael R; Diallo, Mamadou S

2012-08-21

298

Luminescence of carbazolyl-containing polymers doped with iridium chelates  

NASA Astrophysics Data System (ADS)

White light emission is shown to be obtainable at room temperature through the mixing of poly-N-vinylcarbazole (PVC) host fluorescence with fac-tris(2-phenylpyridyl)Ir(III) [Ir(ppy)3] and bis[2-(2'-benzothienyl)pyridinato-N,C3'](acetylacetonate)iridium (III) [Btp2Ir(acac)] dopant phosphorescence whereas at very low temperature through the superposition of poly-N-epoxypropyl-3,6-dibromocarbazole (3,6-DBrPEPC) host and Btp2Ir(acac) dopant phosphorescence emissions. The balance between basic colors is adjusted by the variation of triplet-emitter dopant concentrations. Spin-allowed singlet-singlet energy transfer from the host to iridium chelate dopants by the Forster mechanism is the dominant process in PVC. Spin-forbidden triplet-singlet transfer by the Forster mechanism from the host to the dopant occurs at low temperatures in 3,6-DBrPEPC due to strong spin-orbit coupling induced by the heavy bromine atoms. Spin-allowed transfer from the same host’s triplet excited state to the iridium chelate occurs via electron exchange at high temperatures.

Skryshevskii, Yu. A.

2008-05-01

299

Reciprocal Allosteric Modulation of Carbon Monoxide and Warfarin Binding to Ferrous Human Serum Heme-Albumin  

PubMed Central

Human serum albumin (HSA), the most abundant protein in human plasma, could be considered as a prototypic monomeric allosteric protein, since the ligand-dependent conformational adaptability of HSA spreads beyond the immediate proximity of the binding site(s). As a matter of fact, HSA is a major transport protein in the bloodstream and the regulation of the functional allosteric interrelationships between the different binding sites represents a fundamental information for the knowledge of its transport function. Here, kinetics and thermodynamics of the allosteric modulation: (i) of carbon monoxide (CO) binding to ferrous human serum heme-albumin (HSA-heme-Fe(II)) by warfarin (WF), and (ii) of WF binding to HSA-heme-Fe(II) by CO are reported. All data were obtained at pH 7.0 and 25°C. Kinetics of CO and WF binding to the FA1 and FA7 sites of HSA-heme-Fe(II), respectively, follows a multi-exponential behavior (with the same relative percentage for the two ligands). This can be accounted for by the existence of multiple conformations and/or heme-protein axial coordination forms of HSA-heme-Fe(II). The HSA-heme-Fe(II) populations have been characterized by resonance Raman spectroscopy, indicating the coexistence of different species characterized by four-, five- and six-coordination of the heme-Fe atom. As a whole, these results suggest that: (i) upon CO binding a conformational change of HSA-heme-Fe(II) takes place (likely reflecting the displacement of an endogenous ligand by CO), and (ii) CO and/or WF binding brings about a ligand-dependent variation of the HSA-heme-Fe(II) population distribution of the various coordinating species. The detailed thermodynamic and kinetic analysis here reported allows a quantitative description of the mutual allosteric effect of CO and WF binding to HSA-heme-Fe(II). PMID:23555601

Bocedi, Alessio; De Sanctis, Giampiero; Ciaccio, Chiara; Tundo, Grazia R.; Di Masi, Alessandra; Fanali, Gabriella; Nicoletti, Francesco P.; Fasano, Mauro; Smulevich, Giulietta; Ascenzi, Paolo; Coletta, Massimo

2013-01-01

300

Warfarin modulates the nitrite reductase activity of ferrous human serum heme-albumin.  

PubMed

Human serum heme-albumin (HSA-heme-Fe) displays reactivity and spectroscopic properties similar to those of heme proteins. Here, the nitrite reductase activity of ferrous HSA-heme-Fe [HSA-heme-Fe(II)] is reported. The value of the second-order rate constant for the reduction of [Formula: see text] to NO and the concomitant formation of nitrosylated HSA-heme-Fe(II) (i.e., k on) is 1.3 M(-1) s(-1) at pH 7.4 and 20 °C. Values of k on increase by about one order of magnitude for each pH unit decrease between pH 6.5 to 8.2, indicating that the reaction requires one proton. Warfarin inhibits the HSA-heme-Fe(II) reductase activity, highlighting the allosteric linkage between the heme binding site [also named the fatty acid (FA) binding site 1; FA1] and the drug-binding cleft FA2. The dissociation equilibrium constant for warfarin binding to HSA-heme-Fe(II) is (3.1 ± 0.4) × 10(-4) M at pH 7.4 and 20 °C. These results: (1) represent the first evidence for the [Formula: see text] reductase activity of HSA-heme-Fe(II), (2) highlight the role of drugs (e.g., warfarin) in modulating HSA(-heme-Fe) functions, and (3) strongly support the view that HSA acts not only as a heme carrier but also displays transient heme-based reactivity. PMID:24037275

Ascenzi, Paolo; Tundo, Grazia R; Fanali, Gabriella; Coletta, Massimo; Fasano, Mauro

2013-12-01

301

Reciprocal allosteric modulation of carbon monoxide and warfarin binding to ferrous human serum heme-albumin.  

PubMed

Human serum albumin (HSA), the most abundant protein in human plasma, could be considered as a prototypic monomeric allosteric protein, since the ligand-dependent conformational adaptability of HSA spreads beyond the immediate proximity of the binding site(s). As a matter of fact, HSA is a major transport protein in the bloodstream and the regulation of the functional allosteric interrelationships between the different binding sites represents a fundamental information for the knowledge of its transport function. Here, kinetics and thermodynamics of the allosteric modulation: (i) of carbon monoxide (CO) binding to ferrous human serum heme-albumin (HSA-heme-Fe(II)) by warfarin (WF), and (ii) of WF binding to HSA-heme-Fe(II) by CO are reported. All data were obtained at pH 7.0 and 25°C. Kinetics of CO and WF binding to the FA1 and FA7 sites of HSA-heme-Fe(II), respectively, follows a multi-exponential behavior (with the same relative percentage for the two ligands). This can be accounted for by the existence of multiple conformations and/or heme-protein axial coordination forms of HSA-heme-Fe(II). The HSA-heme-Fe(II) populations have been characterized by resonance Raman spectroscopy, indicating the coexistence of different species characterized by four-, five- and six-coordination of the heme-Fe atom. As a whole, these results suggest that: (i) upon CO binding a conformational change of HSA-heme-Fe(II) takes place (likely reflecting the displacement of an endogenous ligand by CO), and (ii) CO and/or WF binding brings about a ligand-dependent variation of the HSA-heme-Fe(II) population distribution of the various coordinating species. The detailed thermodynamic and kinetic analysis here reported allows a quantitative description of the mutual allosteric effect of CO and WF binding to HSA-heme-Fe(II). PMID:23555601

Bocedi, Alessio; De Sanctis, Giampiero; Ciaccio, Chiara; Tundo, Grazia R; Di Masi, Alessandra; Fanali, Gabriella; Nicoletti, Francesco P; Fasano, Mauro; Smulevich, Giulietta; Ascenzi, Paolo; Coletta, Massimo

2013-01-01

302

Computational methods for intramolecular electron transfer in a ferrous-ferric iron complex  

SciTech Connect

The limitations of common theoretical and molecular computational approaches for predicting electron transfer quantities were assessed, using an archetypal bridged ferrous-ferric electron transfer system in aqueous solution. The basis set effect on the magnitude of the electronic coupling matrix element computed using the quasi-diabatic method was carefully examined, and it was found that the error related to a poor basis set could exceed the thermal energy at room temperature. A range of approaches to determining the external (solvent) reorganization energy were also investigated. Significant improvements from the Marcus continuum model can be obtained by including dipolar Born-Kirkwood-Onsager correction. In this regard we also found that Klamt’s Conductor-Like Screening Model (COSMO) yields estimations of the external reorganization energy similar to those obtained with explicit solvent molecular dynamics simulations, if the fast-frequency modes are neglected, which makes it an attractive alternative to laborious umbrella sampling simulations. As expected, dielectric saturation observed in the first solvation shell decreases the curvature of the potential energy surface, but it nonetheless remains a quadratic function of the reaction coordinate. The linearity of solvent response to the charge redistribution was assessed by analyzing the energy gap autocorrelation function as well as the solvent density and dipole moment fluctuations. Molecular dynamics was also used to evaluate the sign and magnitude of the solvent reorganization entropy, to determine its effect on the predicted electron transfer rate. Finally, we present a simple way of estimating the vibration frequency along the reaction coordinate, which also enables prediction of the mass dependent isotopic signature of electron-transfer reactions.

Zarzycki, Piotr P.; Kerisit, Sebastien N.; Rosso, Kevin M.

2011-07-29

303

5-Aminolevulinic acid combined with ferrous iron enhances the expression of heme oxygenase-1.  

PubMed

5-Aminolevulinic acid (5-ALA) is the naturally occurring metabolic precursor of heme. Heme negatively regulates the Maf recognition element (MARE) binding- and repressing-activity of the Bach1 transcription factor through its direct binding to Bach1. Heme oxygenase (HO)-1 is an inducible enzyme that catalyzes the rate-limiting step in the oxidative degradation of heme to free iron, biliverdin and carbon monoxide. These metabolites of heme protect against apoptosis, inflammation and oxidative stress. Monocytes and macrophages play a critical role in the initiation, maintenance and resolution of inflammation. Therefore, the regulation of inflammation in macrophages is an important target under various pathophysiological conditions. In order to address the question of what is responsible for the anti-inflammatory effects of 5-ALA, the induction of HO-1 expression by 5-ALA and sodium ferrous citrate (SFC) was examined in macrophage cell line (RAW264 cells). HO-1 expression induced by 5-ALA combined with SFC (5-ALA/SFC) was partially inhibited by MEK/ERK and p38 MAPK inhibitor. The NF-E2-related factor 2 (Nrf2) was activated and translocated from the cytosol to the nucleus in response to 5-ALA/SFC. Nrf2-specific siRNA reduced the HO-1 expression. In addition, 5-ALA/SFC increased the intracellular levels of heme in cells. The increased heme indicated that the inactivation of Bach1 by heme supports the upregulation of HO-1 expression. Taken together, our data suggest that the exposure of 5-ALA/SFC to RAW264 cells enhances the HO-1 expression via MAPK activation along with the negative regulation of Bach1. PMID:24530569

Nishio, Yoshiaki; Fujino, Masayuki; Zhao, Mingyi; Ishii, Takuya; Ishizuka, Masahiro; Ito, Hidenori; Takahashi, Kiwamu; Abe, Fuminori; Nakajima, Motowo; Tanaka, Tohru; Taketani, Shigeru; Nagahara, Yukitoshi; Li, Xiao-Kang

2014-04-01

304

Rapid anaerobic benzene oxidation with a variety of chelated Fe(III) forms  

Microsoft Academic Search

Techniques for stimulating aromatic hydrocarbon degradation in anaerobic portions of contaminated aquifers could be helpful in restoring polluted groundwater. Some studies have suggested that chelated Fe (III) might be an alternative electron acceptor that could be used instead of o2 for the bioremediation of aquifers contaminated with aromatic hydrocarbons. However, for this to be feasible an appropriate form of chelated

DEREK R. LOVLEY; JOAN C. WOODWARD; F. H. Chapelle

1996-01-01

305

Removal of heavy metals from a chelated solution with electrolytic foam separation  

SciTech Connect

An experimental study was conducted on the chelation and electrolytic foam separation of trace amounts of copper, nickel, zinc, and cadmium from a synthetic chelated metal wastewater. Sodium ethylenediaminetetraacetate (EDTA), citrate, sodium diethyldithiocarbamate (NDDTC), and potassium ethyl xanthate (KEtX) were used with sodium dodecylsulfate (NaDS) as a foam-producing agent. Experimental results from an electrolytic foam separation process showed that chelating agents NDDTC and KEtX, due to their higher chelating strength and hydrophobic property, can efficiently separate Cu and Ni from chelated compounds (Cu, Ni/EDTA, and Cu, Ni/citrate). In a Cu-EDTA-NDDTC system with a chelating agent/metal ratio of 4, the residual Cu(II) concentration is 0.7 mg/L. The effects of chelating agent types and different chelating agents concentrations on the removal of metal ions were studied. The effect of NaDS dosage on flotation behavior and the efficiency of metal removal were also investigated.

Min-Her Leu; Juu-En Chang; Ming-Sheng Ko [National Cheng Kung Univ., Taiwan (China)

1994-11-01

306

Enhancing uranium solubilization in soils by citrate, EDTA, and EDDS chelating amendments  

Microsoft Academic Search

A systematic study was made of the effects of three soil amendments on the solubilization of uranium from a granitic soil. The aim was to optimize solubilization so as to enhance bioavailability for the purposes of remediation. The three amendments tested were with citrate, EDTA, and EDDS as chelating agents. The effects of pH, chelator concentration, and leaching time were

J. C. Lozano; P. Blanco Rodríguez; F. Vera Tomé; C. Prieto Calvo

307

The Design and Synthesis of Highly Branched and Spherically Symmetric Fluorinated Macrocyclic Chelators  

PubMed Central

Two novel, highly fluorinated macrocyclic chelators with highly branched and spherically symmetric fluorocarbon moieties have been designed and efficiently synthesized. This is achieved by conjugating a spherically symmetric fluorocarbon moiety to the macrocyclic chelator DOTA, with or without a flexible oligo-oxyethylene linker between these two parts. As a result of the spherical symmetry, all 27 fluorine atoms in each fluorinated chelator give a sharp singlet 19F NMR signal. The hydrophilicity and the 19F relaxation behavior of fluorinated chelators can be modulated by the insertion of a flexible linker between the fluorocarbon moiety and the macrocyclic linker. These chelators serve as prototypes for 1H-19F dual-nuclei magnetic resonance imaging agents. PMID:20585414

Jiang, Zhong-Xing; Yu, Y. Bruce

2010-01-01

308

Role of pH in metal adsorption from aqueous solutions containing chelating agents on chitosan  

SciTech Connect

The role of pH in adsorption of Cu(II) from aqueous solutions containing chelating agents on chitosan was emphasized. Four chelating agents including ethylenediaminetetraacetic acid (EDTA), citric acid, tartaric acid, and sodium gluconate were used. It was shown that the adsorption ability of Cu(II) on chitosan from its chelated solutions varied significantly with pH variations. The competition between coordination of Cu(II) with unprotonated chitosan and electrostatic interaction of the Cu(II) chelates with protonated chitosan took place because of the change in solution pH during adsorption. The maximum adsorption capacity was obtained within each optimal pH range determined from titration curves of the chelated solutions. Coordination of Cu(II) with the unprotonated chitosan was found to dominate at pH below such an optimal pH value.

Wu, F.C.; Tseng, R.L. [Lien Ho Junior Coll. of Technology, Maio-Li (Taiwan, Province of China). Dept. of Chemical Engineering and Environmental Engineering] [Lien Ho Junior Coll. of Technology, Maio-Li (Taiwan, Province of China). Dept. of Chemical Engineering and Environmental Engineering; Juang, R.S. [Yuan Ze Univ., Chung-li (Taiwan, Province of China)] [Yuan Ze Univ., Chung-li (Taiwan, Province of China)

1999-01-01

309

Toward resolving the unsettled role of iron chelation therapy in myelodysplastic syndromes.  

PubMed

Transfusion dependent low risk myelodysplastic syndromes (MDS) patients, eventually develop iron overload. Iron toxicity, via oxidative stress, can damage cellular components and impact organ function. In thalassemia major patients, iron chelation therapy lowered iron levels with recovery of cardiac and liver functions and significant improvement in survival. Several noncontrolled studies show inferior survival in MDS patients with iron overload, including an increase in transplant-related mortality and infection risk while iron chelation appears to improve survival in both lower risk MDS patients and in stem cell transplant settings. Collated data are presented on the pathophysiological impact of iron overload; measuring techniques and chelating agents' therapy positive impact on hematological status and overall survival are discussed. Although suggested by retrospective analyses, the lack of clear prospective data of the beneficial effects of iron chelation on morbidity and survival, the role of iron chelation therapy in MDS patients remains controversial. PMID:24641787

Merkel, Drorit G; Nagler, Arnon

2014-07-01

310

Chelation Shows Benefit in Diabetic Patients After Heart Attack, But Findings Do Not Support Its Routine Use  

MedlinePLUS

... years). They were assigned randomly to receive 40 infusions of either the disodium EDTA chelation solution or ... Participants also were randomly assigned to receive 40 infusions of either the disodium EDTA chelation solution or ...

311

Clinically Approved Iron Chelators Influence Zebrafish Mortality, Hatching Morphology and Cardiac Function  

PubMed Central

Iron chelation therapy using iron (III) specific chelators such as desferrioxamine (DFO, Desferal), deferasirox (Exjade or ICL-670), and deferiprone (Ferriprox or L1) are the current standard of care for the treatment of iron overload. Although each chelator is capable of promoting some degree of iron excretion, these chelators are also associated with a wide range of well documented toxicities. However, there is currently very limited data available on their effects in developing embryos. In this study, we took advantage of the rapid development and transparency of the zebrafish embryo, Danio rerio to assess and compare the toxicity of iron chelators. All three iron chelators described above were delivered to zebrafish embryos by direct soaking and their effects on mortality, hatching and developmental morphology were monitored for 96 hpf. To determine whether toxicity was specific to embryos, we examined the effects of chelator exposure via intra peritoneal injection on the cardiac function and gene expression in adult zebrafish. Chelators varied significantly in their effects on embryo mortality, hatching and morphology. While none of the embryos or adults exposed to DFO were negatively affected, ICL -treated embryos and adults differed significantly from controls, and L1 exerted toxic effects in embryos alone. ICL-670 significantly increased the mortality of embryos treated with doses of 0.25 mM or higher and also affected embryo morphology, causing curvature of larvae treated with concentrations above 0.5 mM. ICL-670 exposure (10 µL of 0.1 mM injection) also significantly increased the heart rate and cardiac output of adult zebrafish. While L1 exposure did not cause toxicity in adults, it did cause morphological defects in embryos at 0.5 mM. This study provides first evidence on iron chelator toxicity in early development and will help to guide our approach on better understanding the mechanism of iron chelator toxicity. PMID:25329065

Hamilton, Jasmine L.; Hatef, Azadeh; Imran ul-haq, Muhammad; Nair, Neelima; Unniappan, Suraj; Kizhakkedathu, Jayachandran N.

2014-01-01

312

Near-infrared spectra of ferrous mineral mixtures and methods for their identification in planetary surface spectra  

NASA Astrophysics Data System (ADS)

Iron-bearing minerals are a major component of planetary surfaces, and many can be identified by their characteristic absorption bands in the near-infrared (NIR). Here we present laboratory NIR spectra of a wide range of common Fe-bearing minerals (e.g., olivines, pyroxenes), glasses, and mineral/glass mixtures. We then use this suite of spectra to evaluate the effects of mixtures on mineral detection methods, including olivine and pyroxene spectral indices developed for the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) onboard Mars Reconnaissance Orbiter. We find that although these indices can be compromised by minerals with atypical compositions, mineral mixtures, and the presence of other ferrous minerals, these issues can generally be mitigated by visual inspection of the spectra. However, a special case occurs when the mineral or mixture in question is spectrally indistinguishable from a more common mineral. In particular, we show that spectra of high-calcium pyroxene mixed with Fe-bearing glass can be virtually indistinguishable from common Fe-bearing olivine compositions. This effect, combined with the fact that Fe-bearing glass is generally much more difficult to detect than other ferrous minerals, may be causing glass occurrences on planetary surfaces to be underreported. In support of this hypothesis, we use Mars Express OMEGA observations to show that previous olivine detections in the north polar sand sea on Mars are actually more consistent with local mixing of glass and pyroxene. To address these issues, we present an alternative ferrous mineral identification method based on the position and shape of the 1 and 2 ?m iron absorption bands, which are sensitive to mineralogy, composition, and mineral mixtures in planetary surface spectra, including glass and mixtures with glass. Using Chandrayaan-1 Moon Mineralogy Mapper (M3) observations of Aristarchus Crater on the Moon, we show that these band parameters can reveal subtle spectral variations and can produce mineralogical maps at an exceptional level of detail.

Horgan, Briony H. N.; Cloutis, Edward A.; Mann, Paul; Bell, James F.

2014-05-01

313

Major role for FeoB in Campylobacter jejuni ferrous iron acquisition, gut colonization, and intracellular survival.  

PubMed

To assess the importance of ferrous iron acquisition in Campylobacter physiology and pathogenesis, we disrupted and characterized the Fe2+ iron transporter, FeoB, in Campylobacter jejuni NCTC 11168, 81-176, and ATCC 43431. The feoB mutant was significantly affected in its ability to transport 55Fe2+. It accumulated half the amount of iron than the wild-type strain during growth in an iron-containing medium. The intracellular iron of the feoB mutant was localized in the periplasmic space versus the cytoplasm for the wild-type strain. These results indicate that the feoB gene of C. jejuni encodes a functional ferrous iron transport system. Reverse transcriptase PCR analysis revealed the cotranscription of feoB and Cj1397, which encodes a homolog of Escherichia coli feoA. C. jejuni 81-176 feoB mutants exhibited reduced ability to persist in human INT-407 embryonic intestinal cells and porcine IPEC-1 small intestinal epithelial cells compared to the wild type. C. jejuni NCTC 11168 feoB mutant was outcompeted by the wild type for colonization and/or survival in the rabbit ileal loop. The feoB mutants of the three C. jejuni strains were significantly affected in their ability to colonize the chick cecum. And finally, the three feoB mutants were outcompeted by their respective wild-type strains for infection of the intestinal tracts of colostrum-deprived piglets. Taken together, these results demonstrate that FeoB-mediated ferrous iron acquisition contributes significantly to colonization of the gastrointestinal tract during both commensal and infectious relationship, and thus it plays an important role in Campylobacter pathogenesis. PMID:16988218

Naikare, Hemant; Palyada, Kiran; Panciera, Roger; Marlow, Denver; Stintzi, Alain

2006-10-01

314

O{sub 2}-mediated oxidation of ferrous nitrosylated human serum heme-albumin is limited by nitrogen monoxide dissociation  

SciTech Connect

Research highlights: {yields} Human serum heme-albumin displays globin-like properties. {yields} O{sub 2}-mediated oxidation of ferrous nitrosylated human serum heme-albumin. {yields} Allosteric modulation of human serum heme-albumin reactivity. {yields} Rifampicin is an allosteric effector of human serum heme-albumin. {yields} Human serum heme-albumin is a ROS and NOS scavenger. -- Abstract: Human serum heme-albumin (HSA-heme-Fe) displays globin-like properties. Here, kinetics of O{sub 2}-mediated oxidation of ferrous nitrosylated HSA-heme-Fe (HSA-heme-Fe(II)-NO) is reported. Values of the first-order rate constants for O{sub 2}-mediated oxidation of HSA-heme-Fe(II)-NO (i.e., for ferric HSA-heme-Fe formation) and for NO dissociation from HSA-heme-Fe(II)-NO (i.e., for NO replacement by CO) are k = 9.8 x 10{sup -5} and 8.3 x 10{sup -4} s{sup -1}, and h = 1.3 x 10{sup -4} and 8.5 x 10{sup -4} s{sup -1}, in the absence and presence of rifampicin, respectively, at pH = 7.0 and T = 20.0 {sup o}C. The coincidence of values of k and h indicates that NO dissociation represents the rate limiting step of O{sub 2}-mediated oxidation of HSA-heme-Fe(II)-NO. Mixing HSA-heme-Fe(II)-NO with O{sub 2} does not lead to the formation of the transient adduct(s), but leads to the final ferric HSA-heme-Fe derivative. These results reflect the fast O{sub 2}-mediated oxidation of ferrous HSA-heme-Fe and highlight the role of drugs in modulating allosterically the heme-Fe-atom reactivity.

Ascenzi, Paolo, E-mail: ascenzi@uniroma3.it [Interdepartmental Laboratory of Electron Microscopy, University Roma Tre, Via della Vasca Navale 79, I-00146 Roma (Italy) [Interdepartmental Laboratory of Electron Microscopy, University Roma Tre, Via della Vasca Navale 79, I-00146 Roma (Italy); National Institute for Infectious Diseases I.R.C.C.S. 'Lazzaro Spallanzani', Via Portuense 292, I-00149 Roma (Italy); Gullotta, Francesca; Gioia, Magda; Coletta, Massimo [Department of Experimental Medicine and Biochemical Sciences, University of Roma 'Tor Vergata', Via Montpellier 1, I-00133 Roma (Italy) [Department of Experimental Medicine and Biochemical Sciences, University of Roma 'Tor Vergata', Via Montpellier 1, I-00133 Roma (Italy); Interuniversity Consortium for the Research on the Chemistry of Metals in Biological Systems, Piazza Umberto I 1, I-87100 Bari (Italy); Fasano, Mauro [Department of Structural and Functional Biology, and Center of Neuroscience, University of Insubria, Via Alberto da Giussano 12a, I-21052 Busto Arsizio, VA (Italy)] [Department of Structural and Functional Biology, and Center of Neuroscience, University of Insubria, Via Alberto da Giussano 12a, I-21052 Busto Arsizio, VA (Italy)

2011-03-04

315

Iron chelation therapy in myelodysplastic syndromes: where do we stand?  

PubMed Central

Anemia leading to transfusion dependency (TD) and iron overload (IO) is commonly observed in patients with myelodysplastic syndromes (MDS). In MDS, TD and IO have been retrospectively associated with inferior survival and worse clinical outcomes, including cardiac, hepatic and endocrine dysfunction, and, in some analyses, with leukemic progression and infectious complications. Although suggested by retrospective analyses, clear prospective documentation of the beneficial effects of iron chelation therapy (ICT) on organ function and survival in MDS patients with TD and IO is currently lacking. Consequently, the role of ICT in MDS patients with TD and IO remains a very controversial aspect in the management of MDS. In this review, the authors summarize the current knowledge regarding IO in MDS and the role of ICT. PMID:23991926

Mitchell, Mhairi; Gore, Steven D; Zeidan, Amer M

2014-01-01

316

Control of cytoplasmic calcium with photolabile tetracarboxylate 2-nitrobenzhydrol chelators.  

PubMed Central

This paper introduces nitr-2, a new Ca2+ chelator designed to release Ca2+ upon illumination with near UV (300-400 nm) light. Before illumination nitr-2 has Ca2+ dissociation constants of 160 and 630 nM in 0.1 and 0.3 M ionic strength respectively; after photoconversion to a nitrosobenzophenone the values shift to 7 and 18 microM, high enough to liberate substantial amounts of Ca2+ under intracellular conditions. The speed of release is limited by a dark reaction with rate constant 5 s-1. Aplysia central neurons injected with nitr-2 and exposed to UV light exhibit two separate Ca2+-dependent membrane currents: one carried by potassium ions and one a nonspecific cation current. A quantitative estimate of the spatial distribution of intracellular [Ca2+] changes in large cells filled with a high concentration of nitr-2 and exposed to an intense UV flash is offered. PMID:3098316

Tsien, R Y; Zucker, R S

1986-01-01

317

Synthesis, characterization and some adsorption properties of TMMA chelating resin  

NASA Astrophysics Data System (ADS)

In order to separate U(VI) ions and lanthanide ions from acidic media, N, N, N', N'-tetramethylmalonamide, (TMMA), chelating resin was synthesized by chemically bonding the functional group to the main chain of chloromethylstyrene-divinylbenzene copolymer. Characterization of the resin in terms of IR, solid-NMR, porosity and elemental analysis suggested that TMMA was uniformly linked to the polymer particles following the expected synthetic scheme and that the introduction ratio was ca. 75%. The uptake behavior of Ce(III) ions and of U(VI) ions from different acidic media were investigated using the batch technique. The kinetic and equilibrium studies showed that the obtained resin is promising for the proposed separation.

Nogami, M.; Ismail, I. M.; Yamaguchi, M.; Suzuki, K.

2003-02-01

318

Employment of a macrocyclic amine bifunctional chelate to label antibodies  

SciTech Connect

Conjugation of antibodies (ABs) with bifunction chelates (BFCs) is an effective method to produce immunodiagnostic and immunotherapeutic agents. Most BFCs employ multidentate acetate ligands to chelate metallic radionuclides. The authors have designed a BFC where a cyclam analogue tetradentate macrocyclic amine (MA) is the complexing moiety, MA was linked to the AB using a 3 step process. The epsilon-amine groups on the AB was conjugated using m-maleimidobenzoyl-N-hydroxysuccinimide ester. A MA derivative with a free thiol group was added to produce the final product. The conjugated AB was used to bind Cu-64 (tl/2=12hr). Cu-64 was used because of its availability and because its analog Cu-67 can be used therapeutically. The effects of conjugation and radiolabeling on the denaturation of rabbit-anti-HSA antibodies were determined by affinity chromatography and molecular exclusion HPLC. Non-specific binding (NSB) was minimized by washing the labeled conjugated ABs bound to a Sepharose-HSA affinity column with 1 mM EDTA. No exchange of Cu-64 from the MA to EDTA occured in greater than or equal to 72 hrs while most NSB Cu-64 was exchangeable. An average of 0.5 +- 0.2 BFC groups per AB can be conjugated with 65% active AB remaining. A series of experiments demonstrated that labeling the BFC with Tc-99m prior to conjugation was effective in attaching Tc-99m to the ABs with less than or equal to 10% denaturation. These results indicate the efficacy of MA based BFCs for producing radiocopper and Tc-99m labeled ABs.

Franz, J.; Barefield, E.K.; Freeman, G.M.; Volkert, W.A.; Holmes, R.A.

1985-05-01

319

Arsenite sequestration by nanosized ferrous minerals after bioreduction of arsenic-sorbed lepidocrocite by Shewanella putrefaciens  

NASA Astrophysics Data System (ADS)

X-ray absorption spectroscopy was used in combination with high resolution transmission electron microscopy, X-ray powder diffraction, and Mössbauer spectroscopy to obtain detailed information on arsenic and iron speciation in the products of anaerobic reduction of pure and As(V)- or As(III)-adsorbed lepidocrocite (?-FeOOH) by Shewanella putrefaciens ATCC 12099. We found that this strain is capable of using both Fe(III) in lepidocrocite and As(V) in solution or adsorbed on lepidocrocite surfaces as electron acceptors. Bioreduction of lepidocrocite in the absence of arsenic resulted in the formation of hydroxycarbonate green rust 1 [FeII4FeIII2(OH)12CO3: GR1(CO3)], which completely converted into ferrous- carbonate hydroxide (FeII2(OH)2CO3: FCH). Bioreduction of As(III)-adsorbed lepidocrocite also led to the formation of GR1(CO3) prior to formation of FCH, but the presence of As(III) slows down this transformation, leading to the co-occurrence of both phases. At the end of this experiment, As(III) was found to be adsorbed on the surfaces of GR1(CO3) and FCH. Bioreduction of As(V)-bearing lepidocrocite led directly to the formation of FCH in association with nanometer-sized particles of a minor As-rich Fe(OH)2 phase, with no evidence for green rust formation. At the end of this experiment, As(V) was fully converted to As(III) and dominantly sorbed at the surface of the Fe(OH)2 nanoparticles as oligomers binding to the edges of Fe(OH)6 octahedra in the octahedral layers of Fe(OH)2. These multinuclear As(III) surface complexes are characterized by As-As pairs at a distance of 3.32 ± 0.02 Å and by As-Fe pairs at a distance of 3.50 ± 0.02 Å and represent a new form of As(III) surface complexes. Chemical analyses show that the majority of As(III) produced in the experiments with As present is associated with iron-bearing hydroxycarbonate or hydroxide solids, reinforcing the idea that, at least under some circumstances, bacterial reduction can promote As(III) sequestration instead of mobilizing it into solution.

Ona-Nguema, G.; Morin, G.; Wang, Y.; Juillot, F.; Abdelmoula, M.; Ruby, C.; Guyot, F.; Calas, G.; Brown, G.

2008-12-01

320

Fine and ultrafine emission dynamics from a ferrous foundry cupola furnace.  

PubMed

Aerosol size distributions from ferrous foundry cupola furnaces vary depending on semicontinuous process dynamics, time along the tap-to-tap cycle, dilution ratio, and the physical and chemical nature of the charge and fuel. All of these factors result in a highly time-dependent emission of particulate matter (PM) 2.5 pm or less in aerodynamic diameter (PM2.5)--even on a mass concentration basis. Control measures are frequently taken on the basis of low-reliability parameters such as emission factors and loosely established mass ratios of PM2.5 to PM 10 microm or less in aerodynamic diameter (PM1.0). The new environmental requirements could entail unexpected and undesired drawbacks and uncertainties in the meaning and effectiveness of process improvement measures. The development of process-integrated and flue-gas cleaning measures for reduction of particle emissions requires a better knowledge of generation mechanisms during melting. Available aerosol analyzers expand the range of control issues to be tackled and contribute to greatly reduce the uncertainty of engineering decisions on trace pollutant control. This approach combines real-time size distribution monitoring and cascade impactors as preseparators for chemical or morphological analysis. The results allow for establishing a design rationale and performance requirement for control devices. A number size distribution below 10 microm in aerodynamic equivalent diameter was chosen as the main indicator of charge influence and filter performance. Size distribution is trimodal, with a coarse mode more than 12 microm that contributes up to 30% of the total mass. A temporal series for these data leads to identification of the most relevant size ranges for a specific furnace (e.g., the most penetrating size range). In this cupola, this size range is between 0.32 and 0.77 microm of aerodynamic equivalent diameter and defines the pollution control strategy for metals concentrating within this size range. Scrap quality effect is best monitored at less than 0.2 microm in aerodynamic equivalent diameter and has been confirmed as strongly dependent on the physical state of the charge. PMID:20480855

Meléndez, Antton; García, Estibaliz; Carnicer, Pedro; Pena, Egoitz; Larrión, Miren; Legarreta, Juan Andres; Gutiérrez-Cañas, Cristina

2010-05-01

321

Hydrogen peroxide-independent generation of superoxide by plant peroxidase: hypotheses and supportive data employing ferrous ion as a model stimulus  

PubMed Central

When plants are threaten by microbial attacks or treated with elicitors, alkalization of extracellular space is often induced and thus pH-dependent extracellular peroxidase-mediated oxidative burst reportedly takes place, especially at the site of microbial challenge. However, direct stimulus involved in activation of peroxidase-catalyzed oxidative burst has not been identified to date. Here, we would like to propose a likely role for free ferrous ion in reduction of ferric native peroxidase into ferrous enzyme intermediate which readily produces superoxide anion via mechanism involving Compound III, especially under alkaline condition, thus, possibly contributing to the plant defense mechanism. Through spectroscopic and chemiluminescence (CL) analyses of reactions catalyzed by horseradish peroxidase (HRP), the present study proposed that plant peroxidase-catalyzed production of superoxide anion can be stimulated in the absence of conventional peroxidase substrates but in the presence of free ferrous ion. PMID:25071789

Kimura, Makoto; Umemoto, Yosuke; Kawano, Tomonori

2014-01-01

322

N-Acetylcysteine Protects Rats with Chronic Renal Failure from Gadolinium-Chelate Nephrotoxicity  

PubMed Central

The aim of this study was to evaluate the effect of Gd-chelate on renal function, iron parameters and oxidative stress in rats with CRF and a possible protective effect of the antioxidant N-Acetylcysteine (NAC). Male Wistar rats were submitted to 5/6 nephrectomy (Nx) to induced CRF. An ionic - cyclic Gd (Gadoterate Meglumine) was administrated (1.5 mM/KgBW, intravenously) 21 days after Nx. Clearance studies were performed in 4 groups of anesthetized animals 48 hours following Gd- chelate administration: 1? Nx (n?=?7); 2? Nx+NAC (n?=?6); 3? Nx+Gd (n?=?7); 4?Nx+NAC+Gd (4.8 g/L in drinking water), initiated 2 days before Gd-chelate administration and maintained during 4 days (n?=?6). This group was compared with a control. We measured glomerular filtration rate, GFR (inulin clearance, ml/min/kg BW), proteinuria (mg/24 hs), serum iron (µg/dL); serum ferritin (ng/mL); transferrin saturation (%), TIBC (µg/dL) and TBARS (nmles/ml). Normal rats treated with the same dose of Gd-chelate presented similar GFR and proteinuria when compared with normal controls, indicating that at this dose Gd-chelate is not nephrotoxic to normal rats. Gd-chelate administration to Nx-rats results in a decrease of GFR and increased proteinuria associated with a decrease in TIBC, elevation of ferritin serum levels, transferrin oversaturation and plasmatic TBARS compared with Nx-rats. The prophylactic treatment with NAC reversed the decrease in GFR and the increase in proteinuria and all alterations in iron parameters and TBARS induced by Gd-chelate. NAC administration to Nx rat did not modify the inulin clearance and iron kinetics, indicating that the ameliorating effect of NAC was specific to Gd-chelate. These results suggest that NAC can prevent Gd-chelate nephrotoxicity in patients with chronic renal failure. PMID:22815709

Pereira, Leonardo Victor Barbosa; Shimizu, Maria Heloisa Massola; Rodrigues, Lina Paola Miranda Ruiz; Leite, Claudia Costa; Andrade, Lucia; Seguro, Antonio Carlos

2012-01-01

323

Study of the dose response of the system ferrous ammonium sulfate-sucrose-xylenol orange in acid aqueous solution  

NASA Astrophysics Data System (ADS)

An aqueous solution of ammonium ferrous sulfate-sucrose-xylenol orange in sulfuric acid (FSX) is proposed as a dosimetric system for the processes of gamma irradiation in a range between 0.3 and 6 Gy. This system is based on the indirect oxidation of ferrous ion by an organic compound (sucrose) to ferric ion and on the formation of a color complex of Fe3+ in an acidic medium with xylenol orange (a dye). After gamma radiation, an observable change occurs in the color of the system. Irradiation was executed at three different temperatures (13 °C, 22 °C, and 40 °C). A spectrometric readout method at 585 nm was employed to evaluate the system's dose response. In all of the cases analyzed, the responses had a linear behavior, and a slight effect of irradiation temperature was observed. Post-irradiation response was also evaluated and showed the stability of the solutions 24 h after the irradiation. The results obtained suggest that FSX might be used as a dosimeter for low doses of gamma irradiation because it provides a stable signal, good reproducibility, and an accessible technique for analysis.

Juarez-Calderon, J. M.; Negron-Mendoza, A.; Ramos-Bernal, S.

2014-11-01

324

(Bifunctional chelates of Rh-105, Au-199, and other metallic radionuclides as potential radiotherapeutic agents)  

SciTech Connect

Progress during this period is reported under the following headings: Diethylenetriamine based and related bifunctional chelating agents and their complexation with Rh-105, Au-198, Pd-109, cu-67, In-111, and Co-57; studies of Pd-109, Rh-105 and Tc-99m with bifunctional chelates based on phenylenediamine; establishment of an appropriate protein assay method for conjugated proteins; studies of new bifunctional Bi, Tri and tetradentate amine oxime ligands with Rh-105; IgG and antibody B72.3 conjugation studies by HPLC Techniques with bifunctional metal chelates; and progress on ligand systems for Au(III).

Not Available

1991-01-01

325

[Bifunctional chelates of Rh-105, Au-199, and other metallic radionuclides as potential radiotherapeutic agents  

SciTech Connect

Progress during this period is reported under the following headings: Diethylenetriamine based and related bifunctional chelating agents and their complexation with Rh-105, Au-198, Pd-109, cu-67, In-111, and Co-57; studies of Pd-109, Rh-105 and Tc-99m with bifunctional chelates based on phenylenediamine; establishment of an appropriate protein assay method for conjugated proteins; studies of new bifunctional Bi, Tri and tetradentate amine oxime ligands with Rh-105; IgG and antibody B72.3 conjugation studies by HPLC Techniques with bifunctional metal chelates; and progress on ligand systems for Au(III).

Not Available

1991-12-31

326

The potential application of iron chelators for the treatment of neurodegenerative diseases.  

PubMed

Many forms of neurodegenerative disease, for instance Alzheimer's disease, Parkinson's disease, Friedreich's ataxia, Hallervorden Spatz syndrome and macular degeneration, are associated with elevated levels of redox active metals in the brain and eye. A logical therapeutic approach therefore, is to remove the toxic levels of these metals, copper and iron in particular, by selective chelation. The increased number of iron-selective chelators now available for clinical use has enhanced interest in this type of therapy. This review summarises the recent developments in the design of chelators for treatment of neurodegenerative disease, identifies some of the essential properties for such molecules and suggests some future strategies. PMID:21344071

Hider, Robert C; Roy, Sourav; Ma, Yong Min; Le Kong, Xiao; Preston, Jane

2011-03-01

327

Radiolabeled technetium chelates for use in renal function determinations  

DOEpatents

The present invention is directed to novel radiopharmaceutical imaging agents incorporating Tc-99m as a radiolabel. In particular, the novel imaging agents disclosed herein have relatively high renal extraction efficiencies, and hence are useful for conducting renal function imaging procedures. The novel Tc-99m compounds of a present invention have the following general formula: ##STR1## wherein X is S or N; and wherein Y is --H or wherein Y is ##STR2## and where R.sub.1 is --H, --CH.sub.3, or --CH.sub.2 CH.sub.3 ; R.sub.2 is --H, --CH.sub.2 CO.sub.2 H, --CH.sub.2 CONH.sub.2, --CH.sub.2 CH.sub.2 CO.sub.2 H, --CH.sub.2 CH.sub.2 CONH.sub.2, --CH.sub.3, --CH.sub.2 CH.sub.3, CH.sub.2 C.sub.6 H.sub.5, or --CH.sub.2 OH; and Z is --H, --CO.sub.2 H, --CONH.sub.2, --SO.sub.3 H, --SO.sub.2 NH.sub.2, or --CONHCH.sub.2 CO.sub.2 H; and the Tc is Tc-99m; and water-soluble salts thereof. Of the foregoing, the presently preferred Tc-99m compound of the present invention is Tc-99m-mercaptoacetylglycylglycylglycine (Tc-99m-MAGGG). The present invention is also directed to novel chelating agents that may be reacted with Tc-99m to form the foregoing compounds. Such novel chelating agents have the following general formula. ##STR3## where X and Y have the same definitions as above, and wherein Y' is --H.sub.2 when X is N, or wherein Y' is --H, or a suitable protective group such as --COCH.sub.3, --COC.sub.6 H.sub.5, --CH.sub.2 NHCOCH.sub.3, --COCF.sub.3, or --COCH.sub.2 OH when X is S. The present invention also provides methods for preparing and using the novel Tc-99m compounds.

Fritzberg, Alan (Edmonds, WA); Kasina, Sudhaker (Kirkland, WA); Johnson, Dennis L. (Las Cruces, NM)

1994-01-01

328

Radiolabeled technetium chelates for use in renal function determinations  

DOEpatents

The present invention is directed to novel radiopharmaceutical imaging agents incorporating Tc-99m as a radiolabel. In particular, the novel imaging agents disclosed herein have relatively high renal extraction efficiencies, and hence are useful for conducting renal function imaging procedures. The novel Tc-99m compounds of a present invention have the following general formula: ##STR1## wherein X is S or N; and wherein Y is--H or wherein Y is ##STR2## and where R.sub.1 is --H, --CH.sub.3, or --CH.sub.2 CH.sub.3 ; R.sub.2 is --H, --CH.sub.2 CO.sub.2 H, --CH.sub.2 CONH.sub.2, --CH.sub.2 CH.sub.2 CO.sub.2 H, --CH.sub.2 CH.sub.2 CONH.sub.2, --CH.sub.3, --CH.sub.2 CH.sub.3, CH.sub.2 C.sub.6 H.sub.5, or --CH.sub.2 OH; and Z is --H, --CO.sub.2 H, --CONH.sub.2, --SO.sub.3 H, --SO.sub.2 NH.sub.2, or --CONHCH.sub.2 CO.sub.2 H; and the Tc is Tc-99m; and water-soluble salts thereof. Of the foregoing, the presently preferred Tc-99m compound of the present invention is Tc-99m-mercaptoacetylglycylglycylglycine (Tc-99m-MAGGG). The present invention is also directed to novel chelating agents that may be reacted with Tc-99m to form the foregoing compounds. Such novel chelating agents have the following general formula. ##STR3## where X and Y have the same definitions as above, and wherein Y' is --H.sub.2 when X is N, or wherein Y' is --H, or a suitable protective group such as --COCH.sub.3, --COC.sub.6 H.sub.5, --CH.sub.2 NHCOCH.sub.3, --COCF.sub.3, or --COCH.sub.2 OH when X is S. The present invention also provides methods for preparing and using the novel Tc-99m compounds.

Fritzberg, Alan (Edmonds, WA); Kasina, Sudhakar (Kirkland, WA); Johnson, Dennis L. (Las Cruces, NM)

1990-01-01

329

Soil Remediation of an Arsenic-Contaminated Site With Ferrous Sulfate and Type V Portland Cement  

NASA Astrophysics Data System (ADS)

High levels of arsenic are present in a site adjacent to San Francisco Bay (in East Palo Alto, CA) as a consequence of the activity of a former pesticide manufacturing plant. Most of the readily accessible arsenic at the site has been removed by remedial excavation and surface capping. In-situ fixation of residual arsenic was performed close to the source about 10 years ago where arsenic values in capped soils ranged from 500 to 5000 mg kg-1. The fixation method consisted of the addition of ferrous sulfate (3% w/w), type V Portland cement (10% w/w) and water. Both products were mixed with the contaminated soil to a treatment depth between 1.5 and 9 meters. The treated soil was then capped to prevent weathering. This long-term amended soil offers an opportunity to compare the processes that prevent microbial arsenic reduction and control the immobilization of arsenic in the treated soils versus natural soils, and to study the aging effects of arsenic sorption. Solid phase characterization of soil samples from both the field and controlled laboratory experiments were carried out to study the speciation and bioavailability of arsenic and to ascertain the mechanisms of the arsenic immobilization in the treated soil. These methods included physical description by field observations, X-ray diffraction (XRD), scanning electron microscopy with energy dispersive spectroscopy, total elemental concentrations, and solid phase fractionation by sequential extraction. Both synchrotron X-ray absorption spectroscopy (XAS) and XRD measurements were used to determine oxidation state of arsenic and iron and host phases present in the soil. The remedial treatment was successful in immobilizing the arsenic in the contaminated soil, and decreasing its leachability. Measurements taken at short aging times (during the first month) showed that the treatment was effective in reducing leachable arsenic as evidenced by the TCLP wet test (< 5 mg l-1 leached). The field amendment influenced arsenic speciation. The treated soil in both field samples and short-term laboratory experiments contained only As(V), suggesting that the microbial reduction of arsenic is prevented in the amended soils. Natural soils from cores adjacent to the amended soils contained both As(III) and As(V), and sulfides associated with the arsenic. The addition of Portland cement to soils caused alkaline conditions and pH buffering, changing the pH from 7 before the treatment to 12 afterwards. Calcium and iron sulfates are typical precipitates of iron sulfate and cement applications. Our characterizations suggest that arsenate was incorporated into new phases, either as solid solutions with sulfate or as localized arsenate phases. Arsenic incorporated into these less soluble phases is resistant to desorption and leaching, particularly under changing subsurface conditions.

Illera, V.; O'Day, P. A.; Rivera, N.; Root, R.; Rafferty, M. T.; Vlassopoulos, D.

2005-12-01

330

Chelating stability of an amphoteric chelating polymer flocculant with Cu(II), Pb(II), Cd(II), and Ni(II).  

PubMed

The absorption spectra of Cu(2+), Pb(2+), Cd(2+), and Ni(2+) chelates of an amphoteric chelating polymer flocculant (ACPF) were measured by ultraviolet spectrophotometry, and their compositions and stability constants (?) were calculated. ACPF exhibited three apparent absorption peaks at 204, 251, and 285 nm. The CSS(-) group of ACPF reacted with Cu(2+), Ni(2+), Pb(2+), and Cd(2+) to form ACPF-Cu(2+), ACPF-Ni(2+), ACPF-Pb(2+), and ACPF-Cd(2+) chelates, respectively, according to a molar ratio of 2:1. The maximum absorption peaks of ACPF-Cu(2+), ACPF-Ni(2+), ACPF-Pb(2+), and ACPF-Cd(2+) appeared at 319, 326, 310, and 313.5 nm, respectively. The maximum absorption peaks of the chelates showed significant red shifting compared with the absorption peaks of ACPF. The ? values of the ACPF-Cu(2+), ACPF-Pb(2+), ACPF-Cd(2+), and ACPF-Ni(2+) chelates were (1.37±0.35)×10(12), (3.26±0.39)×10(11), (2.05±0.27)×10(11), and (3.04±0.45)×10(10), respectively. The leaching rate of heavy metal ions from the chelating precipitates decreased with increasing pH. ACPF-Cu(2+), ACPF-Ni(2+), ACPF-Pb(2+), and ACPF-Cd(2+) were very stable at pH?5.6. Cu(2+), Ni(2+), Pb(2+), and Cd(2+) concentrations in the leaching liquors were lower than the corresponding limits specified by the Integrated Wastewater Discharge Standard of China. PMID:24144830

Liu, Lihua; Li, Yanhong; Liu, Xing; Zhou, Zhihua; Ling, Yulin

2014-01-24

331

Chelating stability of an amphoteric chelating polymer flocculant with Cu(II), Pb(II), Cd(II), and Ni(II)  

NASA Astrophysics Data System (ADS)

The absorption spectra of Cu2+, Pb2+, Cd2+, and Ni2+ chelates of an amphoteric chelating polymer flocculant (ACPF) were measured by ultraviolet spectrophotometry, and their compositions and stability constants (?) were calculated. ACPF exhibited three apparent absorption peaks at 204, 251, and 285 nm. The sbnd CSS- group of ACPF reacted with Cu2+, Ni2+, Pb2+, and Cd2+ to form ACPF-Cu2+, ACPF-Ni2+, ACPF-Pb2+, and ACPF-Cd2+ chelates, respectively, according to a molar ratio of 2:1. The maximum absorption peaks of ACPF-Cu2+, ACPF-Ni2+, ACPF-Pb2+, and ACPF-Cd2+ appeared at 319, 326, 310, and 313.5 nm, respectively. The maximum absorption peaks of the chelates showed significant red shifting compared with the absorption peaks of ACPF. The ? values of the ACPF-Cu2+, ACPF-Pb2+, ACPF-Cd2+, and ACPF-Ni2+ chelates were (1.37 ± 0.35) × 1012, (3.26 ± 0.39) × 1011, (2.05 ± 0.27) × 1011, and (3.04 ± 0.45) × 1010, respectively. The leaching rate of heavy metal ions from the chelating precipitates decreased with increasing pH. ACPF-Cu2+, ACPF-Ni2+, ACPF-Pb2+, and ACPF-Cd2+ were very stable at pH ? 5.6. Cu2+, Ni2+, Pb2+, and Cd2+ concentrations in the leaching liquors were lower than the corresponding limits specified by the Integrated Wastewater Discharge Standard of China.

Liu, Lihua; Li, Yanhong; Liu, Xing; Zhou, Zhihua; Ling, Yulin

2014-01-01

332

Bifunctional chelates of RH-105 and AU199 as potential radiotherapeutic agents  

SciTech Connect

Research is presented on new bifunctional chelating ligand systems with stability on the macroscopic and radiochemical levels. The synthesis of the following complexes are described: rhodium 105, palladium 109, and gold 198.

Droege, P.

1997-03-01

333

Efficient bifunctional gallium-68 chelators for positron emission tomography: tris(hydroxypyridinone) ligands  

PubMed Central

A new tripodal tris(hydroxypyridinone) bifunctional chelator for gallium allows easy production of 68Ga-labelled proteins rapidly under mild conditions in high yields at exceptionally high specific activity and low concentration. PMID:21623436

Berry, David J.; Ma, Yongmin; Ballinger, James R.; Tavare, Richard; Koers, Alexander; Sunassee, Kavitha; Zhou, Tao; Nawaz, Saima; Mullen, Gregory E. D.; Hider, Robert C.; Blower, Philip J.

2014-01-01

334

CONTROL OF CHELATOR-BASED UPSETS IN SURFACE FINISHING SHOP WASTE WATER TREATMENT SYSTEMS  

EPA Science Inventory

Actual surface finishing shop examples are used to illustrate the use of process chemistry understanding and analyses to identify immediate, interim and permanent response options for industrial waste water treatment plant (IWTP) upset problems caused by chelating agents. There i...

335

MRI sensing based on the displacement of paramagnetic ions from chelated complexes  

E-print Network

We introduce a mechanism for ion sensing by MRI in which analytes compete with paramagnetic ions for binding to polydentate chelating agents. Displacement of the paramagnetic ions results in alteration of solvent interaction ...

Atanasijevic, Tatjana

336

Fast, Cell-Compatible Click Chemistry with Copper-Chelating Azides for Biomolecular Labeling  

E-print Network

Bring your own copper: Copper-chelating azides undergo much faster click reactions (CuAAC) than nonchelating azides under a variety of biocompatible conditions. This kinetic enhancement allows site-specific protein labeling ...

Uttamapinant, Chayasith

337

CELLULAR MECHANISM OF INTESTINAL PERMEABILITY ALTERATIONS PRODUCED BY CHELATION DEPLETION  

PubMed Central

The absorption of phenolsulfonphthalein (phenol red) was used as a measure in vivo of intestinal permeability in anesthetized rats. A chelating agent, sodium ethylenediaminetetraacetate (NaEDTA), placed in the lumen evoked a fivefold increase in membrane permeability; at the same time the mucosal content of magnesium and calcium decreased significantly. Making either magnesium or calcium available to the luminal surface of the membrane in isotonic solution restored normal permeability and brought the cation contents above the original levels. Electron micrographs of tissues treated in vivo with NaEDTA revealed (a) rounded swellings on the microvilli in the area of the junctional complexes between adjacent epithelial cells, (b) widening of intercellular channels particularly in the region of the intermediate junctions (zonulae adhaerentes), and (c) loss of architectural detail in the region of the desmosomes (maculae adhaerentes) with separation of their dense borders. All of these alterations in fine structure could be reversed by in vivo cation replacements which reinstated normal permeability. The implications of these findings on mechanisms of fluid transport across epithelial membranes are discussed, and a working hypothesis for the role of divalent cations in membrane permeability regulation is presented. PMID:4962241

Cassidy, M. M.; Tidball, C. S.

1967-01-01

338

Chelating water-soluble polymers for waste minimization  

SciTech Connect

Within the DOE complex and in industry there is a tremendous need for advanced metal ion recovery and waste minimization techniques. This project sought to employ capabilities for ligand-design and separations chemistry in which one can develop and evaluate water- soluble chelating polymers for recovering actinides and toxic metals from various process streams. Focus of this work was (1) to develop and select a set of water-soluble polymers suitable for a selected waste stream and (2) demonstrate this technology in 2 areas: removal of (a) actinides and toxic RCRA metals from waste water and (b) recovery of Cu and other precious metals from industrial process streams including from solid catalysts and aqueous waste streams. The R&D was done in 4 phases for each of the 2 target areas: polymer synthesis for scaleup, equipment assembly, process demonstration at a DOE or industrial site, and advanced ligand/polymer synthesis. The TA- 50 site at Los Alamos was thought to be appropriate due to logistics and to its being representative of similar problems throughout the DOE complex.

Smith, B.; Cournoyer, M.; Duran, B.; Ford, D.; Gibson, R.; Lin, M. [Los Alamos National Lab., NM (United States); Meck, A.; Robinson, P. [N,P Energy, Inc. (United States); Robison, T. [Los Alamos National Lab., NM (United States)

1996-11-01

339

Multifunctional iron-chelators with protective roles against neurodegenerative diseases.  

PubMed

The multifactorial nature of Alzheimer's disease (AD), and the absence of a disease modifying drug, makes the development of new multifunctional drugs an attractive therapeutic strategy. Taking into account the hallmarks of AD patient brains, such as low levels of acetylcholine, misfolding of proteins and associated beta-amyloid (A?) aggregation, oxidative stress and metal dyshomeostasis, we have developed a series of compounds that merge three different approaches: metal attenuation, anti-A? aggregation and anti-acetylcholinesterase activity. Therefore, 3-hydroxy-4-pyridinone (3,4-HP) and benzothiazole molecular moieties were selected as starting frameworks due to their well known affinity for iron and A? peptides, respectively. The linkers between these two main functional groups were selected on the basis of virtual screening, so that the final molecule could further inhibit the acetylcholinesterase, responsible for the cholinergic losses. We describe herein the design and synthesis of the new hybrid compounds, followed by the assessment of solution properties, namely iron chelation and anti-oxidant capacity. The compounds were bioassayed for their capacity to inhibit AChE, as well as self- and Zn mediated-A?(1-42) aggregation. Finally, we assessed their effects on the viability of neuronal cells stressed with A?(42). PMID:23487286

Nunes, Andreia; Marques, Sérgio M; Quintanova, Catarina; Silva, Diana F; Cardoso, Sandra M; Chaves, Sílvia; Santos, M Amélia

2013-05-01

340

Alzheimer's beta-amyloid peptide: affinity for metal chelates.  

PubMed

Alzheimer's amyloid peptide, A beta(1-42) and its fragments, A beta(1-28) and A beta(1-16), were chromatographed on IDA-M(II) columns (M: Cu2+, Ni2+ and Zn2+). The retention of A beta(1-42) and its fragments on IDA-Cu(II) could not be reversed in decreasing a gradient of pH, from 7.0 to 4.0. All A beta peptides were recovered from IDA-Ni(II) columns in a decreasing pH gradient from 7.0 to 4.0, within the pH range from 5.6 to 5.1. A beta(1-42) peptide was strongly retained on IDA-Zn(II) at pH 4.0, but its A beta(1-28) and A beta(1-16) were only transiently retained on IDA-Zn(II) columns when applied at pH 6.1. We submit that histidine clusters, residing both in the Alzheimer's beta-amyloid peptide and in most of the APP/APLP superfamily of proteins, constitute high-affinity binding sites for immobilized metal chelates. PMID:9516042

Balakrishnan, R; Parthasarathy, R; Sulkowski, E

1998-02-01

341

Introducing a new azoaromatic pincer ligand. Isolation and characterization of redox events in its ferrous complexes.  

PubMed

The isolation and complete characterization of a new bis-azoaromatic ligand, 2,6-bis(phenylazo)pyridine (L), are described, and its coordination to iron(II) is reported. A pseudo-trigonal-bipyramidal mixed-ligand complex of iron(II), FeLCl2 (1), and a homoleptic octahedral iron complex, mer-[Fe(L)2]ClO4 [2]ClO4, have been synthesized from L and FeCl2 or hydrated Fe(ClO4)2, respectively, in boiling methanol. Determination of the X-ray crystallographic structure together with magnetic data (? 5.06 ?B) and Mössbauer analysis of 1 established a high-spin Fe(II) complex ligated by one neutral 2,6-bis(phenylazo)pyridine ligand. The X-ray crystallographic structure (showing dN-N > 1.30 Å), Mössbauer data, and magnetic susceptibility measurements (? 1.65 ?B) as well as a nearly isotropic EPR signal with only a small metal contribution at g = 1.968, on the other hand, suggest a low-spin Fe(II) complex with a one-electron-reduced radical ligand coordination in [2]ClO4. The ligand and the metal complexes have well-behaved redox properties, with the ligand(s) functioning as the redox-active site(s) responsible for redox events. The uncoordinated ligand, L, displays a reversible one-electron wave at -1.07 V and a quasi-reversible wave at -1.39 V. The partially reduced ligand L(•-) shows a single-line EPR spectrum at g = 2.001, signifying that L(•-) is a free radical. While complex 1 shows a reversible reduction at -0.08 V and an irreversible cathodic response at -0.98 V, the bis-chelate [2]ClO4 undergoes a reversible one-electron oxidation at 0.54 V and three successive reversible one-electron reductions at -0.18, -0.88, and -1.2 V, all occurring at the ligands without affecting the metal ion oxidation state. The electronic structures of the parent monocationic complex [2](+) and its oxidized and reduced forms, generated by exhaustive electrolyses, have been characterized by using a host of spectroscopic techniques and density functional theory (DFT). It is found that the 2,6-bis(phenylazo)pyridine ligand (L) is truly redox noninnocent and is capable of coordinating transition-metal centers in its neutral ([L](0)), monoanionic monoradical ([L(•)](-)), and dianionic diradical ([L(••)](2-)) forms. PMID:24742026

Ghosh, Pradip; Samanta, Subhas; Roy, Suman K; Demeshko, Serhiy; Meyer, Franc; Goswami, Sreebrata

2014-05-01

342

Rapid anaerobic benzene oxidation with a variety of chelated Fe(III) forms  

USGS Publications Warehouse

Fe(III) chelated to such compounds as EDTA, N-methyliminodiacetie acid, ethanol diglycine, humic acids, and phosphates stimulated benzene oxidation coupled to Fe(III) reduction in anaerobic sediments from a petroleum- contaminated aquifer as effectively as or more effectively than nitrilotriacetic acid did in a previously demonstrated stimulation experiment. These results indicate that many forms of chelated Fe(III) might be applicable to aquifer remediation.

Lovley, D.R.; Woodward, J.C.; Chapelle, F.H.

1996-01-01

343

Purification of human copper, zinc superoxide dismutase by copper chelate affinity chromatography  

SciTech Connect

Copper, zinc superoxide dismutase was isolated from human red blood cell hemolysate by DEAE-Sepharose and copper chelate affinity chromatography. Enzyme preparations had specific activities ranging from 3400 to 3800 U/mg and recoveries were approximately 60% of the enzyme activity in the lysate. Copper chelate affinity chromatography resulted in a purification factor of about 60-fold. The homogeneity of the superoxide dismutase preparation was analyzed by sodium dodecyl sulfate-gel electrophoresis, analytical gel filtration chromatography, and isoelectric focusing.

Weslake, R.J.; Chesney, S.L.; Petkau, A.; Friesen, A.D.

1986-05-15

344

Reversal of cadmium induced oxidative stress by chelating agent, antioxidant or their combination in rat  

Microsoft Academic Search

The influence of an antioxidant agent such as N-acetyl cysteine (NAC) or mannitol on the cadmium chelating ability of monoisoamyl 2,3-dimercaptosuccinate (MiADMS) was investigated in cadmium pre-exposed rats. This ester of 2,3-dimercaptosuccinic acid (DMSA), an accepted drug for lead poisoning, being lipophilic in nature was expected to be an efficient cadmium chelator. The treatment of cadmium intoxicated animals with MiADMS

S. K Tandon; S Singh; S Prasad; K Khandekar; V. K Dwivedi; M Chatterjee; N Mathur

2003-01-01

345

In search of a viable reaction pathway in the chelation of a metallo-protein  

Microsoft Academic Search

Misfolded metallo-proteins are potential causal agents in the onset of neuro-degenerative diseases, such as Alzheimer's and Parkinson's Diseases (PD). Experimental results involving metal chelation have shown significant promise in symptom reduction and misfolding reversal. We explore, through atomistic simulations, potential reaction pathways for the chelation of Cu^2+ from the metal binding site in our representation of a partially misfolded alpha-synuclein,

Frisco Rose; Miroslav Hodak; Jerry Bernholc

2010-01-01

346

Chelation therapy and cardiovascular disease: connecting scientific silos to benefit cardiac patients.  

PubMed

Medical practitioners have treated atherosclerotic disease with chelation therapy for over 50 years. Lack of strong of evidence led conventional practitioners to abandon its use in the 1960s and 1970s. This relegated chelation therapy to complementary and alternative medicine practitioners, who reported good anecdotal results. Concurrently, the epidemiologic evidence linking xenobiotic metals with cardiovascular disease and mortality gradually accumulated, suggesting a plausible role for chelation therapy. On the basis of the continued use of chelation therapy without an evidence base, the National Institutes of Health released a Request for Applications for a definitive trial of chelation therapy. The Trial to Assess Chelation Therapy (TACT) was formulated as a 2 × 2 factorial randomized controlled trial of intravenous EDTA-based chelation vs. placebo and high-dose oral multivitamins and multiminerals vs. oral placebo. The composite primary endpoint was death, reinfarction, stroke, coronary revascularization, or hospitalization for angina. A total of 1708 post-MI patients who were 50 years or older with a creatinine of 2.0 or less were enrolled and received 55,222 infusions of disodium EDTA or placebo with a median follow-up of 55 months. Patients were on evidence-based post-MI medications including statins. EDTA proved to be safe. EDTA chelation therapy reduced cardiovascular events by 18%, with a 5-year number needed to treat (NNT) of 18. Prespecified subgroup analysis revealed a robust benefit in patients with diabetes mellitus with a 41% reduction in the primary endpoint (5-year NNT = 6.5), and a 43% 5-year relative risk reduction in all-cause mortality (5-year NNT = 12). The magnitude of benefit is such that it suggests urgency in replication and implementation, which could, due to the excellent safety record, occur simultaneously. PMID:25106084

Peguero, Julio G; Arenas, Ivan; Lamas, Gervasio A

2014-08-01

347

The synthesis and evaluation of 2,3-dihydroxyterephthalamides as actinide chelators  

Microsoft Academic Search

The 2,3-dihydroxyterephthalamides are characterized as chelators for actinide(IV) ions and are investigated as potential nuclear waste remediation agents. Chapter One details the nuclear waste situation in the United States: the formation of nuclear waste, the reason waste cannot remain in its current state, and current approaches to nuclear waste remediation are covered. The properties of the 2,3-dihydroxyterephthalamides as Fe(III) chelators

Christine Julia Gramer

2001-01-01

348

Desferrithiocin analogue iron chelators: iron clearing efficiency, tissue distribution, and renal toxicity  

Microsoft Academic Search

The current solution to iron-mediated damage in transfusional iron overload disorders is decorporation of excess unmanaged\\u000a metal, chelation therapy. The clinical development of the tridentate chelator deferitrin (1, Table 1) was halted due to nephrotoxicity. It was then shown by replacing the 4?-(HO) of 1 with a 3,6,9-trioxadecyloxy group, the nephrotoxicity could be ameliorated. Further structure–activity relationship studies\\u000a have established that

Raymond J. Bergeron; Jan Wiegand; Neelam Bharti; James S. McManis; Shailendra Singh

2011-01-01

349

Soft Chelating Irrigation Protocol Optimizes Bonding Quality of Resilon\\/Epiphany Root Fillings  

Microsoft Academic Search

This study was designed to test the impact of either a strong (MTAD) or a soft (1-hydroxyethylidene-1, 1-bisphosphonate [HEPB]) chelating solution on the bond strength of Resilon\\/Epiphany root fillings. Both 17% EDTA and the omission of a chelator in the irrigation protocol were used as reference treatments. Forty extracted human upper lateral incisors were prepared using different irrigation protocols (n

Gustavo De-Deus; Fátima Namen; João Galan; Matthias Zehnder

2008-01-01

350

Chromium uptake by Spirodela polyrrhiza (L. ) Schleiden in relation to metal chelators and pH  

SciTech Connect

This paper reports the influence of metal chelators, ethylenediaminetetraacetic acid (EDTA) and salicylic acid, and pH on the accumulation of Cr by S. polyrrhiza under the laboratory conditions. This also includes the results of K.D. pond water treatment study by cultured fronds of S. polyrrhiza. In view of the occurrence of metal chelators in natural waters and pH variation the present study would enable to assess the performance of this species under the influence of these factors.

Tripathi, R.D.; Chandra, P. (National Botanical Research Inst., Lucknow (India))

1991-11-01

351

The role of chelation in the treatment of arsenic and mercury poisoning.  

PubMed

Chelation for heavy metal intoxication began more than 70 years ago with the development of British anti-lewisite (BAL; dimercaprol) in wartime Britain as a potential antidote the arsenical warfare agent lewisite (dichloro[2-chlorovinyl]arsine). DMPS (unithiol) and DMSA (succimer), dithiol water-soluble analogs of BAL, were developed in the Soviet Union and China in the late 1950s. These three agents have remained the mainstay of chelation treatment of arsenic and mercury intoxication for more than half a century. Animal experiments and in some instances human data indicate that the dithiol chelators enhance arsenic and mercury excretion. Controlled animal experiments support a therapeutic role for these chelators in the prompt treatment of acute poisoning by arsenic and inorganic mercury salts. Treatment should be initiated as rapidly as possible (within minutes to a few hours), as efficacy declines or disappears as the time interval between metal exposure and onset of chelation increases. DMPS and DMSA, which have a higher therapeutic index than BAL and do not redistribute arsenic or mercury to the brain, offer advantages in clinical practice. Although chelation following chronic exposure to inorganic arsenic and inorganic mercury may accelerate metal excretion and diminish metal burden in some organs, potential therapeutic efficacy in terms of decreased morbidity and mortality is largely unestablished in cases of chronic metal intoxication. PMID:24178900

Kosnett, Michael J

2013-12-01

352

Mathematical modeling of the effects of aerobic and anaerobic chelate bioegradation on actinide speciation.  

SciTech Connect

Biodegradation of natural and anthropogenic chelating agents directly and indirectly affects the speciation, and, hence, the mobility of actinides in subsurface environments. We combined mathematical modeling with laboratory experimentation to investigate the effects of aerobic and anaerobic chelate biodegradation on actinide [Np(IV/V), Pu(IV)] speciation. Under aerobic conditions, nitrilotriacetic acid (NTA) biodegradation rates were strongly influenced by the actinide concentration. Actinide-chelate complexation reduced the relative abundance of available growth substrate in solution and actinide species present or released during chelate degradation were toxic to the organisms. Aerobic bio-utilization of the chelates as electron-donor substrates directly affected actinide speciation by releasing the radionuclides from complexed form into solution, where their fate was controlled by inorganic ligands in the system. Actinide speciation was also indirectly affected by pH changes caused by organic biodegradation. The two concurrent processes of organic biodegradation and actinide aqueous chemistry were accurately linked and described using CCBATCH, a computer model developed at Northwestern University to investigate the dynamics of coupled biological and chemical reactions in mixed waste subsurface environments. CCBATCH was then used to simulate the fate of Np during anaerobic citrate biodegradation. The modeling studies suggested that, under some conditions, chelate degradation can increase Np(IV) solubility due to carbonate complexation in closed aqueous systems.

Banaszak, J.E.; VanBriesen, J.; Rittmann, B.E.; Reed, D.T.

1998-03-19

353

Cytotoxicity and Mutagenicity Study of Waste and Purified Water Samples from Electroplating Industries Prepared by Use of Ferrous Sulfate and Wood Fly Ash  

Microsoft Academic Search

Toxicological safety of the new purification method for electroplating wastewaters (EWW) has been assessed. Method utilizes waste by–product ferrous sulfate and wood fly ash to scavenge heavy metals from EWW. Energy dispersive X–ray fluorescence (EDXRF) analysis of all samples met the law requirements for safe depositing of waste into the environment. The toxicity study consisted of determination of frequency of

Ksenija Durgo; Višnja Oreš?anin; Tea Horvat; Luka Mikeli?; Jasna Franeki? ?oli?; Stipe Luli?

2005-01-01

354

Enhancement of the photocatalytic activity of Ferrous Oxide by doping onto the nano-clinoptilolite particles towards photodegradation of tetracycline.  

PubMed

Photodegradation of tetracycline (TC) aqueous solution by FeO doped onto nano-clinoptilolite particles was investigated using a high pressure Hg lamp as radiation source. Nano-particles of clinoptilolite were prepared using ball-milling of micro crystals of zeolite. The pretreated nano-particles ion exchanged in a ferrous solution and the Fe(II)-exchanged form was calcined at 450°C. All samples were characterized by FT-IR, DRS, SEM and XRD. The degradation extent was determined via UV-Vis absorption spectroscopy and COD. Based on the study of the effect of key operating parameters, the optimal conditions were determined to reach the higher efficiency of the process. The best photocatalytic activity was obtained in presence of the catalyst containing 5.4% FeO. PMID:24875881

Nezamzadeh-Ejhieh, Alireza; Shirzadi, Arezoo

2014-07-01

355

Surface chemistry, microstructure and friction properties of some ferrous-base metallic glasses at temperatures to 750 C  

NASA Technical Reports Server (NTRS)

X-ray photoelectron spectroscopy analysis, transmission electron microscopy, diffraction studies, and sliding friction experiments were conducted with ferrous-base metallic glasses in sliding contact with aluminum oxide at temperatures from room to 750 C in a vacuum of 30 nPa. The results indicate that there is a significant temperature influence on the friction properties, surface chemistry, and microstructure of metallic glasses. The relative concentrations of the various constituents at the surface of the sputtered specimens were very different from the normal bulk compositions. Contaminants can come from the bulk of the material to the surface upon heating and impart boric oxide and silicon oxide at 350 C and boron nitride above 500 C. The coefficient of friction increased with increasing temperature to 350 C. Above 500 C the coefficient of friction decreased rapidly. The segregation of contaminants may be responsible for the friction behavior.

Miyoshi, K.; Buckley, D. H.

1982-01-01

356

Optimisation of polymer coating process for microencapsulating ferrous fumarate for salt double fortification with iodine and iron.  

PubMed

An extrusion-based encapsulation process has been developed for making salt grain-sized iron premix for salt fortification. The first step of extrusion agglomeration process has been studied and reported previously. The focus of this study is on the optimisation of the colour-masking and polymer coating steps. Several colour-masking techniques and polymer encapsulants were investigated at various encapsulation levels. Salt samples prepared by blending the resulting iron premixes with iodised salt retained more than 90% of the original iodine and more than 93% of the ferrous iron after 3 months storage at 35°C and 60% relative humidity (RH). Hydrophilic coatings such as hydroxypropyl methyl cellulose (HPMC) offered more protection at the 10% encapsulation level compared to other coating materials studied. All iron premix formulations exhibited high particle density, good bioavailability and acceptable organoleptic properties. The process using the most effective formulations and optimised operation parameters is ready for pilot scale testing and field studies. PMID:22873200

Yadava, Divya; Olive Li, Yao; Diosady, Levente L; Wesley, Annie S

2012-01-01

357

The discovery of ferrous bottom water conditions in the sealed mid-Proterozoic marine basin, northern part of North China Block: implications to evolution of ocean chemistry  

NASA Astrophysics Data System (ADS)

How the ferrous deep water keep as long as one billion years and why sulfidic water wedge come out near the terrestrial sources supplementary zone are the focus of the evolution of ocean chemistry in mid-Proterozoic. The study of the sealed mid-Proterozoic marine basin found that the low level of pyrite in the black shale of Kuancheng where is far from the terrestrial sources supplementary zone, nevertheless, the level of black shale of Jixian where is far near the terrestrial sources supplementary zone is higher. This may reflect that the shallow-to-deep sulfate concentration gradient the sealed marine basin. The ferrous and deficit of sulfidic bottom water conditions in the sealed marine basin is the great advances in the study. It was proved that the existence of Supercontinent Nuna made the aerobic weathering and the importation of sulfate dropping to the critical point though the bottom water is ferrous in the case of sufficient terrestrial sources supplementary. Due to the long-term stabilization of Supercontinent Nuna, it is possible that the ferrous bottom water conditions in the open ocean in mid-Proterozoic. It is referential for how the global tectonics control the evolution of ocean. The focus for the study of the evolution of ocean chemistry in mid-Proterozoic is how the ferruginous deep water can maintain as long as one billion years, and why sulfidic water wedge would come out near the terrestrial sources region. The present work on the sealed mid-Proterozoic marine basin found the trace level of pyrite exists in the black shale of Kuancheng far away from the terrestrial source region. Nevertheless pyrite is more abundant in the black shale of Jixian nearer from the terrestrial source. This may reflect that the shallow-to-deep sulfate concentration gradient in the sealed marine basin. However the most significant discovery in present work is that the prevailing ferrous bottom water conditions in the sealed marine basin deficit of any sulfidic indicators. Based on comprehensive evidences, we conclude that it was the occurrence of Supercontinent Nuna that decrease the aerobic weathering and sulfate input to a certain critical point that make ferrous bottom water condition in the sealed marine basin possible. The existence of Supercontinent Nuna would be also one of the reason for the wide-spread ferrous condition in the open ocean during that time. The discovery of this work would be of value for exploring the effects of global tectonic development on the evolution of chemistry of paleo-oceans.

Wang, S.; Huang, Y.; Zhang, S.; Shi, X.

2013-12-01

358

Solution structure of Escherichia coli FeoA and its potential role in bacterial ferrous iron transport.  

PubMed

Iron is an indispensable nutrient for most organisms. Ferric iron (Fe(3+)) predominates under aerobic conditions, while during oxygen limitation ferrous (Fe(2+)) iron is usually present. The Feo system is a bacterial ferrous iron transport system first discovered in Escherichia coli K-12. It consists of three genes, feoA, feoB, and feoC (yhgG). FeoB is thought to be the main transmembrane transporter while FeoC is considered to be a transcriptional regulator. Using multidimensional nuclear magnetic resonance (NMR) spectroscopy, we have determined the solution structure of E. coli FeoA. The structure of FeoA reveals a Src-homology 3 (SH3)-like fold. The structure is composed of a ?-barrel with two ?-helices where one helix is positioned over the barrel. In comparison to the standard eukaryotic SH3 fold, FeoA has two additional ?-helices. FeoA was further characterized by heteronuclear NMR dynamics measurements, which suggest that it is a monomeric, stable globular protein. Model-free analysis of the NMR relaxation results indicates that a slow conformational dynamic process is occurring in ?-strand 4 that may be important for function. (31)P NMR-based GTPase activity measurements with the N-terminal domain of FeoB (NFeoB) indicate a higher GTP hydrolysis rate in the presence of potassium than with sodium. Further enzymatic assays with NFeoB suggest that FeoA may not act as a GTPase-activating protein as previously proposed. These findings, together with bioinformatics and structural analyses, suggest that FeoA may have a different role, possibly interacting with the cytoplasmic domain of the highly conserved core portion of the FeoB transmembrane region. PMID:23104801

Lau, Cheryl K Y; Ishida, Hiroaki; Liu, Zhihong; Vogel, Hans J

2013-01-01

359

Effects of exogenous chelators on phytoavailability and toxicity of Pb in Zinnia elegans Jacq.  

PubMed

Chelate-enhanced phytoremediation is considered as an effective method for the extraction of lead (Pb) by plants. However, more detailed studies are needed to evaluate the effect of exogenous chelators on phytoavailability and toxicity of Pb in plants, then to find out the proper applied concentration of chelators to minimize the combined toxicity to the plants and maximize phytoavailable Pb. To clarify these questions, the seed germination test of Zinnia elegans Jacq. exposed to solutions containing Pb and four types of chelators including sodium ethylenediamine tetra-acetic acid (Na2EDTA), oxalic acid, tartaric acid and citric acid was observed. The results showed that the roots and shoots treated with equimolar chelators and Pb were longer than those treated with half and two folds of the molar concentrations of Pb. The growth of seedlings was inhibited by surplus addition of chelators, and the toxicity of complexes was less than that of Pb and chelators. In particular, 2.4 mM EDTA and 1.2 mM oxalic acid significantly (P<0.05) increased Pb uptake when the seeds were treated with 2.4 mM Pb. In the 4.8 mM Pb solution, Pb accumulation in the seedlings was markedly (P<0.05) increased by 4.8 mM EDTA, 2.4 mM tartaric acid, 4.8 mM tartaric acid and 2.4 mM citric acid, and amounted to 6752.4, 6453.8, 6541.4 and 6598.3 microg g(-1), respectively. With the superfluous addition of chelators, Pb accumulation in the seedlings decreased in a concentration-dependent manner. When Pb was used at 2.4 mM, an equimolar concentration of EDTA not only increased Pb uptake but also stimulated the seedling growth. Thus, chelating agents in their appropriately concentrations could counteract Pb toxicity, but superfluous chelators resulted in less Pb uptake and growth inhibition of the seedlings. PMID:17254705

Cui, Shuang; Zhou, Qi-xing; Wei, Shu-he; Zhang, Wei; Cao, Lei; Ren, Li-ping

2007-07-19

360

Chelation of intracellular calcium blocks insulin action in the adipocyte  

SciTech Connect

The hypothesis that intracellular Ca/sup 2 +/ is an essential component of the intracellular mechanism of insulin action in the adipocyte was evaluated. Cells were loaded with the Ca/sup 2 +/ chelator quin-2, by preincubating them with quin-2 AM, the tetrakis(acetoxymethyl) ester of quin-2. Quin-2 loading inhibited insulin-stimulated glucose transport without affecting basal activity. The ability of insulin to stimulate glucose uptake in quin-2-loaded cells could be partially restored by preincubating cells with buffer supplemented with 1.2 mM CaCl/sub 2/ and the Ca/sup 2 +/ ionophore A23187. These conditions had no effect on basal activity and omission of CaCl/sub 2/ from the buffer prevented the restoration of insulin-stimulated glucose uptake by A23187. Quin-2 loading also inhibited insulin-stimulated glucose oxidation and the ability of insulin to inhibit cAMP-stimulated lipolysis without affecting their basal activities. Incubation of cells with 100 ..mu..M quin-2 or quin-2 AM had no effect on intracellular ATP concentration or the specific binding of /sup 125/I=labeled insulin to adipocytes. These findings suggest that intracellular Ca/sup 2 +/ is an essential component in the coupling of the insulin-activated receptor complex to cellular physiological/metabolic machinery. Furthermore, differing quin-2 AM dose-response profiles suggest the presence of dual Ca/sup 2 +/-dependent pathways in the adipocyte. One involves insulin stimulation of glucose transport and oxidation, whereas the other involves the antilipolytic action of insulin.

Pershadsingh, H.A.; Shade, D.L.; Delfert, D.M.; McDonald, J.M.

1987-02-01

361

Modulation of hippocampal synaptic transmission by low concentrations of cell-permeant Ca 2+ chelators: effects of Ca 2+ affinity, chelator structure and binding kinetics  

Microsoft Academic Search

Calcium chelators are commonly used for fluorescence and electrophysiological studies of neuronal Ca2+ signalling. Recently, they have also been used as neuroprotectants. Since they buffer calcium ions, these agents also modify the same signals which are being studied. These properties may be used to modulate Ca2+ signals such as those involved in synaptic transmission, and may explain their neuroprotective mechanism.

I Spigelman; M Tymianski; C. M Wallace; P. L Carlen; A. A Velumian

1996-01-01

362

Significance of serum glucocorticoid and chelatable zinc in depression and cognition in zinc deficiency.  

PubMed

Dietary zinc deficiency elicits neuropsychological symptoms and cognitive dysfunction. To pursue the mechanisms of these symptoms, in the present study, the relationship among serum glucocorticoid, chelatable zinc in the synaptic cleft and brain function based on behavior was examined in young rats fed a zinc-deficient diet for 4 weeks. Serum glucocorticoid level was significantly increased in zinc-deficient rats. However, the induction of in vivo dentate gyrus LTP and object recognition memory were not affected in zinc-deficient rats. Chelatable zinc levels were decreased in the stratum lucidum of the hippocampal CA3, but not in the molecular layer of the dentate gyrus. It is reported that dentate gyrus LTP and object recognition memory are affected in clioquinol (30mg/kg)-administered rats, in which chelatable zinc is significantly decreased in the molecular layer of the dentate gyrus. Thus, the significant decrease in chelatable zinc in the molecular layer of the dentate gyrus may be required for object recognition memory deficit in zinc deficiency. On the other hand, the time of grooming in the open-field test was decreased in zinc-deficient rats. Immobility time in the forced swim test was increased in zinc-deficient rats, but not in clioquinol-administered rats, in which chelatable zinc was more markedly decreased than in zinc-deficient rats, suggesting that the lack of chelatable zinc does not increase depression-like behavior. These results suggest that the chronic increase in serum glucocorticoid level is involved in the increase in depression-like behavior rather than the decrease in chelatable zinc after 4-week zinc deficiency. PMID:21946308

Takeda, Atsushi; Tamano, Haruna; Ogawa, Taisuke; Takada, Shunsuke; Ando, Masaki; Oku, Naoto; Watanabe, Mitsugu

2012-01-01

363

Iron: Mammalian defense systems, mechanisms of disease, and chelation therapy approaches  

Microsoft Academic Search

During the past 6 decades, much attention has been devoted to understanding the uses, metabolism and hazards of iron in living systems.1 A great variety of heme and non-heme iron-containing enzymes have been characterized in nearly all forms of life. The existence of both ferrous and ferric ions in low- and high-spin configuration, as well as the ability of the

G. J. Kontoghiorghes; E. D. Weinberg

1995-01-01

364

Public health department response to mercury poisoning: the importance of biomarkers and risks and benefits analysis for chelation therapy.  

PubMed

Chelation therapy is often used to treat mercury poisoning. Public health personnel are often asked about mercury toxicity and its treatment. This paper provides a public health department response to use of a mercury-containing cosmetic in Minnesota, a perspective on two unpublished cases of chelation treatment for postulated mercury toxicity, and comments on the use of a nonsystemic treatment for removal of mercury following the Iraqi seed coat poisoning incident. Physicians should evaluate sources of exposure, biomarkers, and risks and benefits before recommending chelation therapy for their patients. Potential risks to chelation therapy and its little understood subtle or latent effects are areas of public health concern. PMID:24197663

McKay, Charles A

2013-12-01

365

PHARMACOLOGICAL PROPERTIES OF ORALLY AVAILABLE, AMPHIPATHIC POLYAMINOCARBOXYLIC ACID CHELATORS FOR ACTINIDE DECORPORATION  

PubMed Central

Commonly used water-soluble polyaminocarboxylic acid (PACA) chelators, such as (EDTA) and DTPA, require intravenous or subcutaneous administration due to their poor bioavailability. The bioavailability of PACAs can be improved by the addition of differing lengths of alkyl side chains that alter amphipathic properties. Orally administered amphipathic triethylenetetramine pentaacetic acid (TT) compounds are efficacious for decorporation of Pu and Am. The synthesis, efficacy, binding affinities, and some initial pharmacokinetics properties of amphipathic TT chelators are reviewed. 14C-Labeled C12TT and C22TT chelators are reasonably well absorbed from the intestine and have a substantial biliary/fecal excretion pathway, unlike DTPA, which is mostly excreted in the urine. Whole body retention times are increased as a function of increasing lipophilicity. Neutron-induced autoradiography studies demonstrate that the oral administration of the chelators can substantially inhibit the redistribution of 239Pu in skeletal tissues. In summary, amphipathic TT-based chelators have favorable bioavailability, have a significant biliary excretion pathway, have demonstrated efficacy for americium and plutonium and are thus good candidates for further development. Furthermore, some of the pharmacological properties can be manipulated by changing the lengths of the alkyl side chains and this may have some advantage for decorporation of certain metals and radionuclides. PMID:20699705

Miller, Scott C.; Wang, Xuli; Bowman, Beth M.

2010-01-01

366

Iron Chelators with Topoisomerase-Inhibitory Activity and Their Anticancer Applications  

PubMed Central

Abstract Significance: Iron and topoisomerases are abundant and essential cellular components. Iron is required for several key processes such as DNA synthesis, mitochondrial electron transport, synthesis of heme, and as a co-factor for many redox enzymes. Topoisomerases serve as critical enzymes that resolve topological problems during DNA synthesis, transcription, and repair. Neoplastic cells have higher uptake and utilization of iron, as well as elevated levels of topoisomerase family members. Separately, the chelation of iron and the cytotoxic inhibition of topoisomerase have yielded potent anticancer agents. Recent Advances: The chemotherapeutic drugs doxorubicin and dexrazoxane both chelate iron and target topoisomerase 2 alpha (top2?). Newer chelators such as di-2-pyridylketone-4,4,-dimethyl-3-thiosemicarbazone and thiosemicarbazone -24 have recently been identified as top2? inhibitors. The growing list of agents that appear to chelate iron and inhibit topoisomerases prompts the question of whether and how these two distinct mechanisms might interplay for a cytotoxic chemotherapeutic outcome. Critical Issues: While iron chelation and topoisomerase inhibition each represent mechanistically advantageous anticancer therapeutic strategies, dual targeting agents present an attractive multi-modal opportunity for enhanced anticancer tumor killing and overcoming drug resistance. The commonalities and caveats of dual inhibition are presented in this review. Future Directions: Gaps in knowledge, relevant biomarkers, and strategies for future in vivo studies with dual inhibitors are discussed. Antioxid. Redox Signal. 00, 000–000. PMID:22900902

2013-01-01

367

Comparison of various iron chelators and prochelators as protective agents against cardiomyocyte oxidative injury  

PubMed Central

Oxidative stress is a common denominator of numerous cardiovascular disorders. Free cellular iron catalyzes formation of highly toxic hydroxyl radicals and iron chelation may thus be an effective therapeutic approach. However, using classical iron chelators in diseases without iron overload poses risks that necessitate more advanced approaches, such as prochelators that are activated to chelate iron only under disease-specific oxidative stress conditions. In this study, three cell membrane-permeable iron chelators (clinically-used deferasirox and experimental SIH and HAPI) and five boronate-masked prochelator analogs were evaluated for their ability to protect cardiac cells against oxidative injury induced by hydrogen peroxide. Whereas the deferasirox-derived agents TIP and TRA-IMM displayed negligible protection and even considerable toxicity, aroylhydrazone prochelators BHAPI and BSIH-PD provided significant cytoprotection and displayed lower toxicity following prolonged cellular exposure compared to their parent chelators HAPI and SIH, respectively. Overall, the most favorable properties in terms of protective efficiency and low inherent cytotoxicity were observed with aroylhydrazone prochelator BSIH. BSIH efficiently protected both H9c2 rat cardiomyoblast-derived cells as well as isolated primary rat cardiomyocytes against hydrogen peroxide-induced mitochondrial and lysosomal dysregulation and cell death. At the same time, BSIH was non-toxic at concentrations up to its solubility limit (600 µM) and 72-hour incubation. Hence, BSIH merits further investigation for prevention and/or treatment of cardiovascular disorders associated with a known (or presumed) component of oxidative stress. PMID:24992833

Jansová, Hana; Machá?ek, Miloslav; Wang, Qin; Hašková, Pavlína; Jirkovská, Anna; Pot??ková, Eliška; Kielar, Filip; Franz, Katherine J.; Šim?nek, Tomáš

2014-01-01

368

Heavy metal bioavailability and chelate mobilization efficiency in an assisted phytoextraction process.  

PubMed

The heavy metal bioavailable fraction of a soil is a core parameter to verify the potential risks of contaminant exposure to organisms or plants. The purpose of the present work is to identify the bioavailable metal fraction in soils treated with chelates. This fraction was evaluated directly by analyzing metal concentrations in soil solution and indirectly using sequential extraction procedures. The metal bioavailable fraction was compared with metal accumulated in plant leaves, grown in both untreated and chelate-treated reactors. In order to verify the effect of the readily and slowly biodegradable chelates [S,S]-ethylenediaminedisuccinic acid (EDDS), methylglycine diacetic acid (MGDA), and ethylenediaminetetraacetic acid (EDTA) on metal speciation in soils, a simulation of chelate treatment was made and metal concentrations in different soil compartments before and after the simulation were compared. Lead concentration in the soil solution was positively correlated with metal concentration in the test plants. The soluble fraction showed the best correlation with metal concentration in soil solution. The simulation of the chelate treatment demonstrated that EDTA and EDDS were able to extract part of the organic- and sulfide-bound fraction, which are less available to plants. PMID:18253843

Cao, Alessia; Cappai, Giovanna; Carucci, Alessandra; Lai, Tiziana

2008-04-01

369

Application of anion-exchange resin to remove lipophilic chelates from liposomes  

SciTech Connect

Lipophilic chelates such as 8-hydroxyquinoline, acetylacetone, and tropolone are useful to load high levels of radioactive cations into the inner aqueous compartments of liposomes for investigating the fate of liposomes by the technique of gamma imaging or gamma-ray perturbed angular correlation measurements. However, if lipophilic chelates are not completely removed from liposomes the very same lipophilic chelates can also cause leakage of the entrapped cations from liposomes. Thus, it is essential to make sure that all the lipophilic chelates are removed from liposomes after the loading process. The results of the present study show that more than 99.85% of acetylacetone in liposomal suspension can be removed by a minicolumn of AG1-X8 (phosphate form) anion exchange resin. Virtually all the 8-hydroxyquinoline and tropolone in liposomal suspension are adsorbed tightly to the resin. The procedure is rapid, and the dilution of liposomes is minimal. For experiments involving high levels of gamma-emitting radionuclides, the cleaning up process of removing lipophilic chelates from liposomes can be conveniently operated behind a lead glass.

Choi, H.O.; Hwang, K.J.

1986-07-01

370

Four-coordinate organoboron compounds with a ?-conjugated chelate ligand for optoelectronic applications.  

PubMed

Four-coordinate organoboron compounds with a ?-conjugated chelate backbone have emerged recently as highly attractive materials for a number of applications including use as emitters and electron-transport materials for organic light-emitting diodes (OLEDs) or organic field transistors, photoresponsive materials, and sensory and imaging materials. Many applications of this class of boron compounds stem from the electronic properties of the ?-conjugated chelate backbone. Charge-transfer transitions from an aromatic substituent attached to the boron center of the ?-conjugated chelate backbone and steric congestion have also been found to play important roles in the luminescent and photochromic properties of the four-coordinate boron compounds. This article provides an update-to-date account on the application aspects of this important class of compounds in materials science with the emphasis on OLED applications and photochromic switching. PMID:21604707

Rao, Ying-Li; Wang, Suning

2011-12-19

371

Zn2+ chelation improves recovery by delaying spreading depression-like events  

PubMed Central

We previously reported Zn2+ chelation improved recovery of synaptic potentials after transient oxygen and glucose deprivation in brain slices. Such an effect could be due to reduced accumulation of Zn2+ in postsynaptic neurons, or could also be due to prevention of the onset of spreading depression-like events. A combination of optical and electrical recording was used here to demonstrate that Zn2+ chelation is effective because it delays spreading depression-like events. If the duration of oxygen/glucose deprivation was sufficient to generate a spreading depression-like event, irrecoverable Ca2+-dependent loss of synaptic potentials occurred, regardless of Zn2+ availability. These results identify a key mechanism underlying protective effects of Zn2+ chelation, and emphasize the importance of evaluating spreading depression-like events in studies of neuroprotection. PMID:20856149

Carter, Russell E.; Weiss, John H.; Shuttleworth, C. William

2010-01-01

372

Radiopharmaceutical stannic Sn-117m chelate compositions and methods of use  

DOEpatents

Radiopharmaceutical compositions including .sup.117m Sn labeled stannic (Sn.sup.4+) chelates are provided. The chelates are preferably polyhydroxycarboxylate, such as oxalates, tartrates, citrates, malonates, gluconates, glucoheptonates and the like. Methods of making .sup.117m Sn-labeled (Sn.sup.4+) polyhydroxycarboxylic chelates are also provided. The foregoing pharmaceutical compositions can be used in methods of preparing bone for scintigraphical analysis, for radiopharmaceutical skeletal imaging, treatment of pain resulting from metastatic bone involvement, treatment of primary bone cancer, treatment of cancer resulting from metastatic spread to bone from other primary cancers, treatment of pain resulting from rheumatoid arthritis, treatment of bone/joint disorders and to monitor radioactively the skeletal system.

Srivastava, Suresh C. (Setauket, NY); Meinken, George E. (Middle Island, NY)

2001-01-01

373

Copper extraction from chloride solutions with mixtures of solvating and chelating reagents  

SciTech Connect

Equimolar mixtures of N,N,N{prime},N{prime}-tetrahexylpyridine-3,5-dicarboxamide (L) with 2-hydroxy-5-t-octylbenzophenone oxime or 1-phenyldecane-1,3-dione (HB), were used to extract copper from chloride solutions of various concentration of chloride ions. Chloride ions were then scrubbed out with water or ammoniacal solutions and copper was transferred from the solvate CuCl{sub 2}L{sub 2} to chelate CuB{sub 2}. Both studied systems permit effective extraction of copper and removal of chloride ions from the organic phase. Some protonation of solvating reagent L occurs, however, when copper is stripped from the chelate with hydroxyoxime. This negative effect can be suppressed when 1-phenyldecane-1,3-dione is used as a chelating agent. The scrubbing of chloride ions must be then carried out with ammoniacal solutions to avoid simultaneous stripping of copper.

Borowiak-Resterna, A.; Szymanowski, J.

2000-01-01

374

Immobilization of BMP-2 on a nano-hydroxyapatite-coated titanium surface using a chitosan calcium chelating agent.  

PubMed

We conducted experiments to determine the most effective calcium chelating agents for use in enhancing adhesion of human bone marrow mesenchymal stem cells (BM-MSCs) on nano-hydroxyapatite (nHAp)-coated titanium substrates by covalently immobilizing bone morphogenetic protein-2 (BMP-2). The quantity of amine groups on the chitosan chelated surface was 7 µg/surface area, and it was 1.4 µg/surface area on the alendronate chelated surface. The quantity of BMP-2 on the BMP-2 immobilized surface chelated with chitosan (4 ng/surface area) was higher than that on BMP-2 immobilized surface chelated with alendronate (2.2 ng/surface area). Contact angles of the nHAp-coated titanium, alendronate chelated, chitosan chelated, and BMP-2 immobilized surfaces chelated with alendronate were 68.8 ± 3.6°, 78.2 ± 1.9°, 74.8 ± 5.2°, and 76.0 ± 2.5°, respectively. The contact angle of the BMP-2 immobilized surface chelated with chitosan was significantly lower (56.2 ± 2.0°) than that of any of the other groups. BM-MSCs on the chitosan surface and BMP-2 immobilized on the surface chelated with chitosan appeared to be healthy and showed a spindle-like fibroblastic morphology. In addition, BM-MSCs on these surfaces appeared to have the ability to differentiate into bone-forming cells. We suggest that chitosan can be used as an effective calcium chelating agent for implants. PMID:23661555

Kim, Sung-Hyun; Park, Jung-Keug; Hong, Kug-Sun; Jung, Hyun-Suk; Seo, Young-Kwon

2013-07-01

375

Bioavailability study of dried microencapsulated ferrous sulfate--SFE 171--by means of the prophylactic-preventive method.  

PubMed

Microencapsulated ferrous sulfate with soy lecithin (SFE-171) has been used as an iron source for the fortification of milk and dairy products. With the purpose to extend the use of this agent to other kind of foods or even to pharmaceutical preparations for oral administration, the SFE-171 was turned into a fluid powder (SFE-171-P) by means of vacuum drying. The iron bioavailability (BioFe) of SFE-171-P was evaluated in this work by means of the prophylactic-preventive method in rats, using ferrous sulfate as reference standard. Both iron sources were separately added to a basal diet of low iron content in a concentration of 10 mg iron/kg diet. Two groups of 10 weaned rats 25 days old received the fortified diets during 28 days, while a third group of the same size received the basal diet without iron additions. The weights and haemoglobin concentrations (HbC) of every animal were determined before and after the treatment, thus allowing the calculation of the mass of iron incorporated into haemoglobin (HbFe) during this period. The BioFe of the iron sources were obtained as the percentage ratio between the HbFe and the mass of iron consumed by each animal. The results were also given as Relative Biological Value (RBV), which relates the BioFe of the studied source with that of the reference standard. The liver iron concentration (LIC) of each animal was determined at the end of the experiment in order to evaLuate the influence of the studied iron sources on the liver iron stores. SFE-171-P presented BioFe, RBV and LIC values of (47 +/- 7)%, 109% and (46.6 +/- 3.4) mg/kg respectively, while the corresponding values for the reference standard were of (43 +/- 7)%, 100% and (45.0 +/- 4.7) mg/kg. These results show that the drying process used to produce the SFE-171-P does not affect its bioavailability, which is also adequate for the potential use of this product in food fortification or with pharmaceutical purposes. PMID:11846015

Lysionek, A E; Zubillaga, M B; Salgueiro, M J; Caro, R A; Weill, R; Boccio, J R

2001-01-01

376

The development of diabetes mellitus and chronic liver disease in long term chelated beta thalassaemic patients.  

PubMed Central

We studied 29 patients with thalassaemia major who had received intensive chelation for between 6.2 and 8.8 years. All patients had normal oral glucose tolerance tests before subcutaneous chelation therapy was introduced and 22 of 29 patients had normal liver function tests. At the end of the period of study 12 patients still had normal oral glucose tolerance (7 with normal liver function tests and 5 with chronic active hepatitis). On the other hand, 11 patients had developed impaired glucose tolerance tests (3 patients had normal liver function tests, 5 with chronic active hepatitis and 3 with cirrhosis), and 6 patients had developed frank diabetes mellitus (one with chronic active hepatitis and 5 with cirrhosis). Patients with chronic active hepatitis showed 91% positivity for one or more hepatitis B markers whilst all patients with cirrhosis were positive. Ferritin levels before subcutaneous chelation in patients with normal oral glucose tolerance tests were lower than in those patients with abnormal oral glucose tolerance or diabetes (P less than 0.05) but none had normal serum ferritin levels. In addition, a positive correlation was found between glucose area under the curve after chelation therapy and serum ferritin levels (r = 0.47, P less than 0.01). It is apparent that long term chelation therapy does not prevent the development of abnormal oral glucose tolerance in chronically transfused patients. More intensive chelation therapy is needed to prevent tissue damage. Chronic liver disease may have an important role to play in the deterioration of glucose tolerance. PMID:3543913

De Sanctis, V.; D'Ascola, G.; Wonke, B.

1986-01-01

377

Chelator-induced phytoextraction of zinc and copper by rice seedlings.  

PubMed

Solution culture was carried to investigate capacity of synthetic aminopolycarboxylic acids (ethylenediamine tetraacetate, N-hydroxyethylenediaminetriacetic acid, and diethylenetriamine-pentaacetate) for enhancing botanical removal and transport of heavy metals (Cu and Zn) by plants. Biodegradable organic acids (citric acid, malic acid, and oxalic acid) were also selected as alternatives to compare them with synthesized chelating agents for effectiveness. Young rice seedlings (Oryza sativa L. cv. XZX 45) were grown in nutrient solutions treated with single or combined metal solutions in presence or absence of chelating compounds. Calculation by chemical equilibrium program VISUAL MINTEQ showed that different chelating compounds had various complex potential with Cu(2+) and Zn(2+) ions, in which synthetic chelators exhibited higher complexed capability than biodegradable organic acids. All applied synthetic aminopolycarboxylic acids significantly decreased removal of metal from nutrient solution (p < 0.01), while more or less effects of organic acids supplied on biosorptive potential were observed with all treatments (p > 0.05), compared with the treatment without metal ligands. Synthetic aminopolycarboxylic acids significantly decreased metal concentrations in plant materials in all treatments (p < 0.01). However, biodegradable organic acids decreased metal concentrations in roots (p < 0.01), but enhanced them in shoots (p < 0.01). Results obtained indicated that synthetic aminopolycarboxylic acids decreased uptake of metals by rice seedlings, but translocation of metals complexed within plant materials was evident. Although exogenous biodegradable organic acids showed negligible effect on botanical removal of metals, metals complexed with organic acids was more mobile than those complexed with other chelating agents. These information collected here had important implication for the use of biodegradable metal chelators in transport of essential micronutrients in plant nutrition. PMID:24442416

Yu, Xiao-Zhang; Wang, Dun-Qiu; Zhang, Xue-Hong

2014-05-01

378

Design and synthesis of chelating diamide sorbents for the separation of lanthanides  

SciTech Connect

A nanoporous sorbent designed around chelating iminodiacetamide (“IDA-Amide”) moiety was made on mesoporous silica (MCM-41) and evaluated for lanthanide separations (Ce3+, Nd3+, Eu3+, Gd3+, and Lu3+). The effects of solution pH on lanthanide binding were studied, as well as sorption kinetics, and competition from other metal ions. The IDA-Amide SAMMS® demonstrated an interesting difference in the kinetics of sorption of the lanthanide ions in the order of Lu3+ > Eu3+ > Gd3+ > Nd3+ > Ce3+ . The close proximity of the ligands in the IDA-Amide SAMMS® may allow for multiple metal-ligand interactions (“macromolecular chelation”).

Fryxell, Glen E.; Chouyyok, Wilaiwan; Rutledge, Ryan D.

2011-06-01

379

Hyperbranched chelating polymers for the polymer-assisted ultrafiltration of boric acid  

SciTech Connect

Two hyperbranched chelating polymers, glucoheptonamide derivatives of dendrimetric poly(amido amine) and poly(ethylene imine), were employed in polymer-assisted ultrafiltration and concentration of boron from aqueous feed streams. For feeds containing approximately 1 mM B (10 ppm), volume reduction factors of 20 were observed in cyclic adsorption-desorption. The concentrations of both polymers declined due to permeation through an ultrafiltration membrane with pore sizes which should have retained them. Acid-catalyzed hydrolysis of the amide linkages between the polymer backbone and the chelating side groups is implicated in this loss of polymer mass and effectiveness.

Smith, B.M.; Todd, P.; Bowman, C.N. [Univ. of Colorado, Boulder, CO (United States). Dept. of Chemical Engineering] [Univ. of Colorado, Boulder, CO (United States). Dept. of Chemical Engineering

1999-07-01

380

Removal of nickel by chelating drugs from the organs of nickel poisoned rats  

SciTech Connect

The chelating drugs namely ethylenediamine tetraacetic acid (EDTA), 1,2,cyclohexylenediamine tetraacetic acid (CDTA), hydroxyethylenediamine triacetic acid (HEDTA) diethylenetriamine pentaacetic acid (DTPA), and triethylenetetraamine hexaacetic acid (TTHA), were examined for the mobilization of nickel from body organs of sham operated and partially hepatectomized rats in early nickel poisoning. These chelating drugs successfully reduced the body burden of nickel from both the nickel treated experimental groups. EDTA was relatively more effective in reducing the hepatic content of nickel while CDTA and HEDTA were more effective in reducing its renal content. These drugs also reduced nickel burden in heart and lung to variable degrees.

Dwivedi, P.P.; Athar, M.; Hasan, S.K.; Srivastava, R.C.

1986-01-01

381

Recent advances in chelator design and labelling methodology for (68) Ga radiopharmaceuticals.  

PubMed

Gallium-68 has the potential to become the technetium-99m of positron emission tomography with ideal decay characteristics and a long-lived parent isotope for generator production. The work in the area of (68) Ga is focused on two key areas: (1) synthesis of a library of bifunctional chelators, which can be quickly radiolabelled to form kinetically inert complexes under mild conditions compatible with biomolecules and (2) development of radiosynthetic methodologies for clinical use and to facilitate radiolabelling of a wide range of chelators under mild conditions. Recent advances in these areas, with particular focus on the past 3?years, are covered herein. PMID:24497011

Burke, Benjamin P; Clemente, Gonçalo S; Archibald, Stephen J

2014-04-01

382

Hepatobiliary delivery of polyaminopolycarboxylate chelates: Synthesis and characterization of a cholic acid conjugate of EDTA and biodistribution and imaging studies with its indium-111 chelate  

SciTech Connect

A conjugate in which the steroid nucleus of cholic acid was linked to EDTA via an 11-atom spacer was obtained by reacting the succinimidyl ester of cholic acid with the amine formed by reaction of a benzyl isothiocyanate derivative of EDTA with N-(tert-butoxycarbonyl)ethylenediamine and subsequent deprotection. Potentiometric titration studies with model complexes showed that the EDTA moiety retained the ability to form 1:1 chelates of high thermodynamic stability, although formation constants were some 3-4 log K units lower for complexes of the conjugate than for the analogous chelates with underivatized EDTA. A complex formed between the cholic acid-EDTA conjugate and 111InIII was clearly rapidly into the liver when injected iv into mice, with subsequent excretion from the liver into the gastrointestinal tract being complete within 1 h of injection. Radioscintigraphic imaging studies conducted in a rabbit given the 111In-labeled conjugate also showed early liver uptake followed by rapid clearance from the liver into the intestine, with good visualization of the gallbladder in images obtained at 20-25 min postinjection. It is concluded that conjugation to cholic acid provides a useful means for the hepatobiliary delivery of EDTA chelates that otherwise exhibit predominantly extracellular distribution and renal clearance.

Betebenner, D.A.; Carney, P.L.; Zimmer, A.M.; Kazikiewicz, J.M.; Bruecher, E.S.; Sherry, A.D.; Johnson, D.K. (Abbott Laboratories, Abbott Park, Illinois (USA))

1991-03-01

383

Dual fortification of salt with iodine and iron: a randomized, double-blind, controlled trial of micronized ferric pyrophosphate and encapsulated ferrous fumarate in southern India  

Microsoft Academic Search

Background:Dual fortification of salt with iodine and iron could be a sustainable approach to combating iodine and iron deficiencies. Objective:We compared the efficacy of dual-fortified salt (DFS) made by using 2 proposed contrasting formulas-one fortifying with iron as micronized ground ferric pyrophosphate (MGFePP) and the other with iron as encapsulated ferrous fumarate (EFF)-with the efficacy of iodized salt (IS) in

M. Andersson; P. Thankachan; S. Muthayya; R. B. Goud; A. V. Kurpad; R. F. Hurrell

2008-01-01

384

Nuclear resonance vibrational spectroscopy applied to [Fe(OEP)(NO)] : the vibrational assignments of five-coordinate ferrous heme-nitrosyls and implications for electronic structure  

Microsoft Academic Search

This study presents Nuclear Resonance Vibrational Spectroscopy (NRVS) data on the five-coordinate (5C) ferrous heme-nitrosyl complex [Fe(OEP)(NO)] (1, OEP² = octaethylporphyrinato dianion) and the corresponding ¹N¹O labeled complex. The obtained spectra identify two isotope sensitive features at 522 and 388 cm¹, which shift to 508 and 381 cm¹, respectively, upon isotope labeling. These features are assigned to the Fe-NO stretch

Nicolai Lehnert; Mary Grace I. Galinato; Florian Paulat; George B. Richter-Addo; Wolfgang Sturhahn; Nan Xu; Jiyong Zhao

2010-01-01

385

Development of ceramic material and filtering element technology for disk vacuum filtering units used in dewatering ferrous and nonferrous metal ore concentrates  

Microsoft Academic Search

Question of reducing expenditure for producing a production unit may be resolved by means of filtering elements made of porous\\u000a permeable ceramic materials with a controlled pore size created using the newest technology. Methodology is presented for\\u000a creating sector filtering elements made of porous permeable ceramic based on electrocorundum for disk vacuum filtering units\\u000a used extensively in ferrous and nonferrous

B. L. Krasnyi; V. P. Tarasovskii; A. B. Krasnyi

2009-01-01

386

Characterization of radionuclide-chelating agent complexes found in low-level radioactive decontamination waste. Literature review  

SciTech Connect

The US Nuclear Regulatory Commission is responsible for regulating the safe land disposal of low-level radioactive wastes that may contain organic chelating agents. Such agents include ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), picolinic acid, oxalic acid, and citric acid, and can form radionuclide-chelate complexes that may enhance the migration of radionuclides from disposal sites. Data from the available literature indicate that chelates can leach from solidified decontamination wastes in moderate concentration (1--100 ppm) and can potentially complex certain radionuclides in the leachates. In general it appears that both EDTA and DTPA have the potential to mobilize radionuclides from waste disposal sites because such chelates can leach in moderate concentration, form strong radionuclide-chelate complexes, and can be recalcitrant to biodegradation. It also appears that oxalic acid and citric acid will not greatly enhance the mobility of radionuclides from waste disposal sites because these chelates do not appear to leach in high concentration, tend to form relatively weak radionuclide-chelate complexes, and can be readily biodegraded. In the case of picolinic acid, insufficient data are available on adsorption, complexation of key radionuclides (such as the actinides), and biodegradation to make definitive predictions, although the available data indicate that picolinic acid can chelate certain radionuclides in the leachates.

Serne, R.J.; Felmy, A.R.; Cantrell, K.J.; Krupka, K.M.; Campbell, J.A.; Bolton, H. Jr.; Fredrickson, J.K. [Pacific Northwest National Lab., Richland, WA (United States)

1996-03-01

387

Influence of chelating ligands on bioavailability and mobility of iron in plant growth media and their effect on radish growth  

Microsoft Academic Search

In this study, the effects of chelating ligands on iron movement in growth medium, iron bioavailability, and growth of radish sprouts (Raphanus sativus) were investigated. Iron is an important nutrient for plant growth, yet the insoluble state of iron hydroxides in alkaline conditions decreases its bioavailability. Iron chelates increase iron uptake and have been used in agriculture to correct iron

H. Hasegawa; M. Azizur Rahman; K. Saitou; M. Kobayashi; C. Okumura

2011-01-01

388

Improvement of Oxidative and Metabolic Parameters by Cellfood Administration in Patients Affected by Neurodegenerative Diseases on Chelation Treatment  

PubMed Central

Objective. This prospective pilot study aimed at evaluating the effects of therapy with antioxidant compounds (Cellfood, and other antioxidants) on patients affected by neurodegenerative diseases (ND), who displayed toxic metal burden and were subjected to chelation treatment with the chelating agent calcium disodium ethylenediaminetetraacetic acid (CaNa2EDTA or EDTA). Methods. Two groups of subjects were studied: (a) 39 patients affected by ND and (b) 11 subjects unaffected by ND (controls). The following blood parameters were analyzed before and after three months' treatment with chelation + Cellfood or chelation + other antioxidants: oxidative status (reactive oxygen species, ROS; total antioxidant capacity, TAC; oxidized LDL, oxLDL; glutathione), homocysteine, vitamin B12, and folate. Results. After 3-months' chelation + Cellfood administration oxLDL decreased, ROS levels were significantly lower, and TAC and glutathione levels were significantly higher than after chelation + other antioxidants treatment, both in ND patients and in controls. Moreover, homocysteine metabolism had also improved in both groups. Conclusions. Chelation + Cellfood treatment was more efficient than chelation + other antioxidants improving oxidative status and homocysteine metabolism significantly in ND patients and controls. Although limited to a small number of cases, this study showed how helpful antioxidant treatment with Cellfood was in improving the subjects' metabolic conditions. PMID:25114898

Fulgenzi, Alessandro; Giuseppe, Rachele De; Bamonti, Fabrizia; Ferrero, Maria Elena

2014-01-01

389

Flow Analysis Method Using Chelating CIM Monolithic Disks for Monitoring Dissolved Labile Copper in Environmental Water Samples  

Microsoft Academic Search

A low pressure flow analysis system incorporating a chelating monolithic disc for the selective retention and elution of Cu(II) from within environmental samples, is reported. Three monolithic discs were modified with either picolinic acid, dipicolinic acid, or dodecyliminodiacetic acid and the extraction and elution efficiency of Cu(II) on the three chelating phases compared. The dipicolinic acid disc showed the highest

Éadaoin Tyrrell; Pavel N. Nesterenko; Brett Paull

2006-01-01

390

Isotopic characterisation of lead in contaminated soils from the vicinity of a non-ferrous metal smelter near Plovdiv, Bulgaria.  

PubMed

Soil samples from the vicinity of a non-ferrous metal smelter near Plovdiv, Bulgaria contained very high concentrations of cadmium, lead and zinc (up to 140, 4900 and 5900 mg kg(-1), respectively). A roadside soil in a relatively uncontaminated area also contained high concentrations of the same metals (24, 1550 and 1870 mg kg(-1), respectively) indicating that the transport of ores could be a source of contamination. Even though the lead isotope ratios in all the samples fell within a very narrow range (for example, 1.186-1.195 for (206)Pb/(207)Pb), the samples could be differentiated into three distinct groups: ores ((206)Pb/(207)Pb and (208)Pb/(207)Pb ratios of 1.1874-1.1884 and 2.4755-2.4807, respectively), current deposition (1.1864 and 2.4704-2.4711, respectively) and local background (1.1927-1.1951 and 2.4772-2.4809, respectively). Although most of the current deposition has its origin in the ores used at the smelter, up to 12% could be from other sources such as petrol lead. PMID:15589652

Bacon, Jeffrey R; Dinev, Nikolai S

2005-03-01

391

Coupling fast water exchange to slow molecular tumbling in Gd3+ chelates: why faster is not always better  

PubMed Central

The influence of dynamics on solution state structure is a widely overlooked consideration in chemistry. Variations in Gd3+ chelate hydration with changing coordination geometry and dissociative water exchange kinetics substantially impact the effectiveness (or relaxivity) of mono-hydrated Gd3+ chelates as T1-shortening contrast agents for MRI. Theory shows that relaxivity is highly dependent upon the Gd3+-water proton distance (rGdH) and yet this distance is almost never considered as a variable in assessing the relaxivity of a Gd3+ chelate as a potential contrast agent. The consequence of this omission can be seen when considering the relaxivity of isomeric Gd3+ chelates that exhibit different dissociative water exchange kinetics. The results described herein show that the relaxivity of a chelate with ‘optimal’ dissociative water exchange kinetics is actually lower than that of an isomeric chelate with ‘sub-optimal’ dissociative water exchange. When the rate of molecular tumbling of these chelates is slowed, an approach that has long been understood to increase relaxivity, the observed difference in relaxivity is increased with the more rapidly exchanging (‘optimal’) chelate exhibiting lower relaxivity than the ‘sub-optimally’ exchanging isomer. The difference between the chelates arises from a non-field dependent parameter: either the hydration number (q) or rGdH. For solution state Gd3+ chelates, changes in the values of q and rGdH are indistinguishable. These parametric expressions simply describe the hydration state of the chelate – i.e. the number and position of closely associating water molecules. The hydration state (q/rGdH6) of a chelate is intrinsically linked to its dissociative water exchange rate kex and the interrelation of these parameters must be considered when examining the relaxivity of Gd3+ chelates. The data presented herein indicates that the changes in the hydration parameter (q/rGdH6) associated with changing dissociative water exchange kinetics has a profound effect on relaxivity and suggest that achieving the highest relaxivities in monohydrated Gd3+ chelates is more complicated than simply “optimizing” dissociative water exchange kinetics. PMID:23841587

Avedano, Stefano; Botta, Mauro; Haigh, Julian S.; Longo, Dario; Woods, Mark

2013-01-01

392

Chelation and permeation of heavy metals using affinity membranes from cellulose acetate–chitosan blends  

Microsoft Academic Search

Affinity membranes have attracted the attention of membrane researchers especially in the field of wastewater treatment specifically in removing heavy metals by chelation from aqueous solutions. In the present work, several membranes are made from either cellulose di-acetate (CA) or CA together with chitosan (CS) solutions, the CS prepared in our lab from shrimp shells or from readymade shrimp or

M. M. Naim; H. E. M. Abdel Razek

2012-01-01

393

Lanthanide Chelates as Bilayer Alignment Tools in NMR Studies of Membrane-Associated Peptides  

NASA Astrophysics Data System (ADS)

Theequimolar complex, consisting of the lipid-like, amphiphilic chelating agent 1,11-bis[distearylamino]-diethylenetriamine pentaacetic acid (DTPA-18) and Tm 3+, is shown by deuterium ( 2H) NMR to be useful in aligning bicelle-like model membranes, consisting of dimyristoylphosphatidylcholine (DMPC) and dihexanoylphosphatidylcholine (DHPC). As shown previously (1996, R. S. Prosser et al., J. Am. Chem. Soc. 118, 269-270), in the absence of chelate, the lanthanide ions bind loosely with the lipid phosphate groups and confer the membrane with a sufficient positive magnetic anisotropy to result in parallel alignment (i.e., average bilayer normal along the field). Apparently, DTPA-18 sequesters the lanthanide ions and inserts into the phospholipid bilayer in such a manner that bilayer morphology is preserved over a wide temperature range (35-70°C). The inherent paramagnetic shifts and line broadening effects are illustrated by 2H NMR spectra of the membrane binding peptide, Leu-enkephalin (Lenk- d2, Tyr-(Gly- d2)-Gly-Phe-Leu-OH), in the presence of varying concentrations of Tm 3+, and upon addition of DTPA-18. Two conclusions could be drawn from this study: (1) The addition of Tm 3+ to the bicelle system is consistent with a conformational change in the surface associated peptide, and this effect is shown to be reversed by addition of the chelate, and (2) The paramagnetic shifts are shown to be significantly reduced by addition of chelate.

Prosser, R. S.; Bryant, H.; Bryant, R. G.; Vold, Regitze R.

1999-12-01

394

Management of transfusional iron overload - differential properties and efficacy of iron chelating agents  

PubMed Central

Regular red cell transfusion therapy ameliorates disease-related morbidity and can be lifesaving in patients with various hematological disorders. Transfusion therapy, however, causes progressive iron loading, which, if untreated, results in endocrinopathies, cardiac arrhythmias and congestive heart failure, hepatic fibrosis, and premature death. Iron chelation therapy is used to prevent iron loading, remove excess accumulated iron, detoxify iron, and reverse some of the iron-related complications. Three chelators have undergone extensive testing to date: deferoxamine, deferasirox, and deferiprone (although the latter drug is not currently licensed for use in North America where it is available only through compassionate use programs and research protocols). These chelators differ in their modes of administration, pharmacokinetics, efficacy with regard to organ-specific iron removal, and adverse-effect profiles. These differential properties influence acceptability, tolerability and adherence to therapy, and, ultimately, the effectiveness of treatment. Chelation therapy, therefore, must be individualized, taking into account patient preferences, toxicities, ongoing transfusional iron intake, and the degree of cardiac and hepatic iron loading. PMID:22287873

Kwiatkowski, Janet L

2011-01-01

395

SPECTROSCOPY, MODELING AND COMPUTATION OF METAL CHELATE SOLUBILITY IN SUPERCRITICAL CO2  

EPA Science Inventory

The objectives of this project are to gain a fundamental understanding of the solubility and stability of metal chelates in supercritical CO2. Extraction with CO2 is a excellent way to remove organic compounds from soils, sludges and aqueous solutions and recent research has demo...

396

Chelating polymers and related supports for separation and preconcentration of trace metals.  

PubMed

This review is concerned mainly with the applications of chelating polymeric resins for the separation and concentration of trace metals from oceans, rivers, streams and other natural systems. Commercially available resins, specially prepared polymers and a selection of other sorbents are described and their uses outlined. Special emphasis is placed on the preconcentration of uranium from sea-water. PMID:18964972

Kantipuly, C; Katragadda, S; Chow, A; Gesser, H D

1990-05-01

397

The impact of succimer chelation on blood cadmium in children with background exposures: a randomized trial.  

PubMed

Succimer lowers blood lead concentrations in children, and the structure of succimer chelates of lead and cadmium are similar. Using blood samples from a randomized trial of succimer for lead poisoning, however, we found that succimer did not lower blood cadmium in children with background exposure. PMID:23601497

Cao, Yang; Chen, Aimin; Bottai, Matteo; Caldwell, Kathleen L; Rogan, Walter J

2013-08-01

398

Modern Chemistry Techniques Applied to Metal Behavior and Chelation in Medical and Environmental Systems ? Final Report  

SciTech Connect

This report details the research and findings generated over the course of a 3-year research project funded by Lawrence Livermore National Laboratory (LLNL) Laboratory Directed Research and Development (LDRD). Originally tasked with studying beryllium chemistry and chelation for the treatment of Chronic Beryllium Disease and environmental remediation of beryllium-contaminated environments, this work has yielded results in beryllium and uranium solubility and speciation associated with toxicology; specific and effective chelation agents for beryllium, capable of lowering beryllium tissue burden and increasing urinary excretion in mice, and dissolution of beryllium contamination at LLNL Site 300; {sup 9}Be NMR studies previously unstudied at LLNL; secondary ionization mass spec (SIMS) imaging of beryllium in spleen and lung tissue; beryllium interactions with aerogel/GAC material for environmental cleanup. The results show that chelator development using modern chemical techniques such as chemical thermodynamic modeling, was successful in identifying and utilizing tried and tested beryllium chelators for use in medical and environmental scenarios. Additionally, a study of uranium speciation in simulated biological fluids identified uranium species present in urine, gastric juice, pancreatic fluid, airway surface fluid, simulated lung fluid, bile, saliva, plasma, interstitial fluid and intracellular fluid.

Sutton, M; Andresen, B; Burastero, S R; Chiarappa-Zucca, M L; Chinn, S C; Coronado, P R; Gash, A E; Perkins, J; Sawvel, A M; Szechenyi, S C

2005-02-03

399

The Potential of Iron Chelators of the Pyridoxal Isonicotinoyl Hydrazone Class as Effective Antiproliferative Agents  

Microsoft Academic Search

acid hydrazides. The effects of these chelators were as- sessed using the human NB cell line, SK-N-MC. Although PIH was far more effective than DFO at preventing Fe uptake from transferrin, it was less effective than DFO at preventing cellular proliferation (DFO IDSO = 22 pmol\\/L; PIH ID50 = 75 RON (Fe) IS ESSENTIAL for cellular growth and divi- sion,

D. R. Richardson; E. H. Tran; P. Ponka

1995-01-01

400

Differential in vitro and cellular effects of iron chelators for hypoxia inducible factor hydroxylases.  

PubMed

Hypoxia inducible factor 1? (HIF-1?), an essential transcriptional factor, is negatively regulated by two different types of oxygen and Fe(2+) -dependent HIF hydroxylases, proline hydroxylase (PHD) and factor inhibiting HIF (FIH), under normoxia. Iron chelators have therefore been used for inducing HIF-1? expression by inhibiting the hydroxylases. In this study, the iron chelators displayed differential effects for PHD and FIH in cells depending on their iron specificity and membrane permeability rather than their in vitro potencies. The membrane permeability of the strict Fe(2+) -chelator potentially inhibited both hydroxylases, whereas the membrane impermeable one showed no inhibitory effect in cells. In contrast, the depletion of the extracellular Fe(3+) ion was mainly correlated to PHD inhibition, and the membrane permeable one elicited low efficacy for both enzymes in cells. The 3'-hydroxyl group of quercetin, a natural flavonoid, was critical for inhibition of intracellular hydroxylases. Since the 3'-methylation of quercetin is induced by catechol-O-methyl transferase, the enzyme may regulate the intracellular activity of quercetin. These data suggest that the multiple factors of iron-chelators may be responsible for regulating the intracellular activity HIF hydroxylases. PMID:23097160

Cho, Eun A; Song, Hyun Kyung; Lee, Sang-Hyeup; Chung, Bong Hyun; Lim, Heon Man; Lee, Myung Kyu

2013-04-01

401

Biodegradable chelating agents for industrial, domestic, and agricultural applications-a review.  

PubMed

Aminopolycarboxylates, like ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA), are chelating agents widely used in several industrial, agricultural, and domestic applications. However, the fact that they are not biodegradable leads to the presence of considerable amounts in aquatic systems, with serious environmental consequences. The replacement of these compounds by biodegradable alternatives has been the object of study in the last three decades. This paper reviews the most relevant studies towards the use of environmentally friendly chelating agents in a large number of applications: oxidative bleaching, detergents and cleaning compositions, scale prevention and reduction, remediation of soils, agriculture, electroplating, waste treatment, and biocides. Nitrilotriacetic acid (NTA), ethylenediaminedisuccinic acid (EDDS), and iminodisuccinic acid (IDS) are the most commonly suggested to replace the nonbiodegradable chelating agents. Depending on the application, the requirements for metal complexation might differ. Metal chelation ability of the most promising compounds [NTA, EDDS, IDS, methylglycinediacetic acid (MGDA), L-glutamic acid N,N-diacetic acid (GLDA), ethylenediamine-N,N'-diglutaric acid (EDDG), ethylenediamine-N,N'-dimalonic acid (EDDM), 3-hydroxy-2,2-iminodisuccinic acid (HIDS), 2-hydroxyethyliminodiacetic acid (HEIDA), pyridine-2,6-dicarboxylic acid (PDA)] with Fe, Mn, Cu, Pb, Cd, Zn, Ca, and Mg was simulated by computer calculations. The advantages or disadvantages of each compound for the most important applications were discussed. PMID:24554295

Pinto, Isabel S S; Neto, Isabel F F; Soares, Helena M V M

2014-10-01

402

[Remediation of Cu-Pb-contaminated loess soil by leaching with chelating agent and biosurfactant].  

PubMed

Because of its strong chelation, solubilization characteristics, the chelating agents and biosurfactant are widely used in remediation of heavy metals and organic contaminated soils. Ethylenediamine tetraacetic acid (EDTA), citric acid (CIT) and dirhamnolipid (RL2) were selected as the eluent. Batch experiments and column experiments were conducted to investigate the leaching effect of the three kinds of eluent, as well as the mixture of biosurfactant and chelating agent for Cu, Pb contaminated loess soil. The results showed that the leaching efficiencies of different eluent on Cu, Pb contaminated loess soil followed the sequence of EDTA > CIT > RL2. At an eluent concentration of 0.02 mol x L(-1), the Cu leaching efficiency was 62.74% (EDTA), 52.28% (CIT) and 15.35% (RL2), respectively; the Pb leaching efficiency was 96.10% (EDTA), 23.08% (CIT) and 14.42% (RL2), respectively. When the concentration of RL2 was 100 CMC, it had synergistic effects on the other two kinds of chelating agent in Cu leaching, and when the concentration of RL2 was 200 CMC, it had antagonism effects. The effect of RL2 on EDTA in Pb leaching was similar to that in Cu leaching. Pb leaching by CIT was inhibited in the presence of RL2. EDTA and CIT could effectively remove Cu and Pb in exchangeable states, adsorption states, carbonate salts and organic bound forms; RL2 could effectively remove Cu and Pb in exchangeable and adsorbed states. PMID:23798147

Liu, Xia; Wang, Jian-Tao; Zhang, Meng; Wang, Li; Yang, Ya-Ti

2013-04-01

403

Formation Damage due to Iron Precipitation in Acidizing Operations and Evaluating GLDA as a Chelating Agent  

E-print Network

solubility in 15 wt% HCl. However, its solubility in 28 wt% HCl is low and it is not readily biodegradable. In this study we studied the formation damage caused by iron precipitation in acidizing operations and tested the chelate L-glutamic acid, N...

Mittal, Rohit

2012-02-14

404

68Ga chelating bioorthogonal tetrazine polymers for the multistep labeling of cancer biomarkers†  

PubMed Central

We have developed a 68Ga metal chelating bioorthogonal tetrazine dextran probe that is highly reactive with trans-cyclooctene modified monoclonal antibodies for multistep imaging applications. Confocal microscopy and positron emission tomography (PET) were used to characterize the dextran probe in vitro and in vivo. PMID:24589653

Yang, Jun; Vera, David R.; Devaraj, Neal K.

2014-01-01

405

Complex Inhibition of Tyrosinase by Thiol-Composed Cu Chelators: A Clue for Designing Whitening Agents  

Microsoft Academic Search

The inhibition of tyrosinase has attracted considerable attention for potential medicinal and cosmetic applications, as well as in agriculture. This study investigated the inhibition effects of thiol-associated Cu chelators and deduced a strategy for designing and\\/or selecting tyrosinase inhibitors. Among the several compounds tested, dithioglycerine (DTGC) was selected for further experiments on the inhibition kinetics on tyrosinase. Different types of

Yong-Doo Park; You-Jeong Lyou; Hwa-Sun Hahn; Myong-Joon Hahn; Jun-Mo Yang

2006-01-01

406

Chelation of neurotoxic zinc levels does not improve neurobehavioral outcome after traumatic brain injury  

PubMed Central

Increases of synaptically released zinc and intracellular accumulation of zinc in hippocampal neurons after traumatic or ischemic brain injury is neurotoxic and chelation of zinc has been shown to reduce neurodegeneration. Although our previous studies showed that zinc chelation in traumatically brain-injured rats correlated with an increase in whole-brain expression of several neuroprotective genes and reduced numbers of apoptotic neurons, the effect on functional outcome has not been determined, and the question of whether this treatment may actually be clinically relevant has not been answered. In the present study, we show that treatment of TBI rats with the zinc chelator calcium EDTA reduces the numbers of injured, Fluoro-Jade- positive neurons in the rat hippocampus 24 hours after injury but does not improve neurobehavioral outcome (spatial memory deficits) two weeks post-injury. Our data suggest that zinc chelation, despite providing short-term histological neuroprotection, fails to improve long-term functional outcome, perhaps because long-term disruptions in homeostatic levels of zinc adversely influence hippocampus-dependent spatial memory. PMID:18556117

Hellmich, Helen L.; Eidson, Kristine; Cowart, Jeremy; Crookshanks, Jeanna; Boone, Deborah K.; Shah, Syed; Uchida, Tatsuo; DeWitt, Douglas S.; Prough, Donald S.

2008-01-01

407

A family of hydroxypyrone ligands designed and synthesized as iron chelators.  

PubMed

The use of chelating agents for iron and aluminum in different clinical applications has found increasing attention in the last thirty years. Desferal, deferiprone and deferasirox, chelating agents nowadays in use, are based on hydroxamic groups, hydroxyl-substituted pyridinones or aromatic ring systems. With the aim of designing new chelators, we synthesized a series of kojic acid derivatives composed by two kojic units joined by linkers variously substituted. The huge advantages of these molecules are that they are easy and cheap to produce. Preliminary works on complex formation equilibria of the first group of ligands with iron and aluminium highlighted extremely good pMe values and gave evidence of the ability to scavenge iron from inside cells. On these bases a second set of bis-kojic ligands, whose linkers between the kojic chelating moieties are differentiated both in terms of type and size, has been designed, synthesized and characterized. The structural characterization of these new ligands is presented, and the protonation and iron(III) complex formation equilibria studied by potentiometry, UV-Visible spectrophotometry, electrospray ionization mass (ESI-MS) and (1)H NMR spectroscopy will be described and discussed. PMID:23859830

Toso, Leonardo; Crisponi, Guido; Nurchi, Valeria M; Crespo-Alonso, Miriam; Lachowicz, Joanna I; Santos, M Amelia; Marques, Sergio M; Niclós-Gutiérrez, Juan; González-Pérez, Josefa M; Domínguez-Martín, Alicia; Choquesillo-Lazarte, Duane; Szewczuk, Zbigniew

2013-10-01

408

Searching for new aluminium chelating agents: a family of hydroxypyrone ligands.  

PubMed

Attention is devoted to the role of chelating agents in the treatment of aluminium related diseases. In fact, in spite of the efforts that have drastically reduced the occurrence of aluminium dialysis diseases, they so far constitute a cause of great medical concern. The use of chelating agents for iron and aluminium in different clinical applications has found increasing attention in the last thirty years. With the aim of designing new chelators, we synthesized a series of kojic acid derivatives containing two kojic units joined by different linkers. A huge advantage of these molecules is that they are cheap and easy to produce. Previous works on complex formation equilibria of a first group of these ligands with iron and aluminium highlighted extremely good pMe values and gave evidence of the ability to scavenge iron from inside cells. On these bases a second set of bis-kojic ligands, whose linkers between the kojic chelating moieties are differentiated both in terms of type and size, has been designed, synthesized and characterized. The aluminium(III) complex formation equilibria studied by potentiometry, electrospray ionization mass spectroscopy (ESI-MS), quantum-mechanical calculations and (1)H NMR spectroscopy are here described and discussed, and the structural characterization of one of these new ligands is presented. The in vivo studies show that these new bis-kojic derivatives induce faster clearance from main organs as compared with the monomeric analog. PMID:24200878

Toso, Leonardo; Crisponi, Guido; Nurchi, Valeria M; Crespo-Alonso, Miriam; Lachowicz, Joanna I; Mansoori, Delara; Arca, Massimiliano; Santos, M Amélia; Marques, Sérgio M; Gano, Lurdes; Niclós-Gutíerrez, Juan; González-Pérez, Josefa M; Domínguez-Martín, Alicia; Choquesillo-Lazarte, Duane; Szewczuk, Zbigniew

2014-01-01

409

BEHAVIORAL CONSEQUENCES OF CHELATOR ADMINISTRATION IN ACUTE CADMIUM TOXICITY (JOURNAL VERSION)  

EPA Science Inventory

The conditioned flavor-aversion paradigm was used to assess the toxicity of acutely administered cadmium and the interaction of cadmium with the heavy-metal chelating agents dimercaprol (BAL) and dimercaptosuccinic acid (DMSA). Shortly after consuming saccharin, rats received cad...

410

662 American Society of Hematology Supportive care and chelation therapy in MDS  

E-print Network

662 American Society of Hematology Supportive care and chelation therapy in MDS: are we saving rate of apoptosis leads to peripheral cytopenias. Anemia is the most frequent cytopenia seen in MDS of MDS are diagnosed per year in the US. Most patients will eventually require transfusions; therefore

Strynadka, Natalie

411

Chelation of molybdenum in Medicago sativa (alfalfa) grown on reclaimed mine tailings.  

PubMed

Extraction and analytical procedures were developed from 1999 to 2005 for the chemical investigation of molybdenum (Mo) in aerial portions of alfalfa ( Medicago sativa L.) grown on a reclaimed mine tailings site at the Highland Valley Copper Mine in British Columbia, Canada. The purification procedures were guided by colorimetric analyses specific for Mo. The Mo levels in freeze-dried plant samples exceeded 100 ppm, which is more than 20 times the maximum level recommended for livestock feed. In contrast to previous work, which detected the inorganic molybdate anion (MoO4(2-)) in alfalfa from the site, the present study identified the major pool of Mo as a chelate bound to malic acid in five sources of plant material. However, the inorganic form of Mo was characterized in aqueous tailings samples, but once imbibed by vegetation, the anion was chelated to the alpha-hydroxy organic acid. Synthetic chelates were synthesized to differentiate the Mo-malate complex from the Mo-citrate by 95Mo NMR. Crystal structure of the synthetic Mo-malate determined that the Mo was bound to two malato ligands as Na 2[MoO2(malate) 2] x 5H2O, which confirmed the structure of the isolates deduced by 95Mo NMR. The chelation of Mo at the site may well explain the apparent lack of long-term clinical effects in cattle grazing the site. PMID:18543934

Steinke, D R; Majak, W; Sorensen, T S; Parvez, M

2008-07-01

412

Chelator-induced bioextraction of heavy metals from artificially contaminated soil by mushroom (Coprinus comatus)  

Microsoft Academic Search

This study investigated the potential use of chelator-induced bioextraction of heavy metals from soil by Coprinus comatus in a pot experiment. Two production waves of the mushroom were obtained to determine biomass and metal concentration. The application of ethylenediaminetetraacetic acid (EDTA) or nitrilotriacetate (NTA) slightly inhibited the growth of C. comatus, but significantly enhanced the accumulation of heavy metals in

Feng Cen; Lan Chen; Yuanjia Hu; Heng Xu

2011-01-01

413

Chelator-induced bioextraction of heavy metals from artificially contaminated soil by mushroom (Coprinus comatus)  

Microsoft Academic Search

This study investigated the potential use of chelator-induced bioextraction of heavy metals from soil by Coprinus comatus in a pot experiment. Two production waves of the mushroom were obtained to determine biomass and metal concentration. The application of ethylenediaminetetraacetic acid (EDTA) or nitrilotriacetate (NTA) slightly inhibited the growth of C. comatus, but significantly enhanced the accumulation of heavy metals in

Feng Cen; Lan Chen; Yuanjia Hu; Heng Xu

2012-01-01

414

Modeling manganese removal in chelating polymer-assisted membrane separation systems for water treatment  

Microsoft Academic Search

The removal of manganese from groundwater, using water-soluble chelating polymers such as polyacrylic acid (PAA) in combination with ultrafiltration (UF), was investigated. The effects of the solution pH and polymer dosages on the manganese removal were evaluated, and the removal efficiency was modeled considering the relevant chemical equilibria. In the absence of polymer, manganese removal with UF membranes alone was

Sang-Chul Han; Kwang-Ho Choo; Sang-June Choi; Mark M. Benjamin

2007-01-01

415

Induced formation of chelating agents by Pseudomonas aeruginosa grown in presence of thorium and uranium  

Microsoft Academic Search

Chelating agents produced by microorganisms enhance the dissolution of iron and increase its mobility and bioavailability. Since there are some similarities in the biological behavior of ferric, thorium and uranuyl ions, microorganisms resistant to thorium and uranium and capable of growing in their presence may produce sequestering agents for these metals in a manner similar to those produced for iron.

E. T. Premuzic; A. J. Francis; M. Lin; J. Schubert

1985-01-01

416

Lumbar spinal ganglia enhancement after Gadolinium chelate administration: a radio-histological correlation  

Microsoft Academic Search

: The aim of the present study was to assess the frequency of enhancement of lumbar spinal ganglia after Gadolinium chelate injection in patients without radiculopathy, and to correlate the enhancement with histology. This study is based on the analysis of MR lumbar examinations conducted on 18 patients without radicular symptoms, or previous surgery of the lumbar spine, or disease

X. Demondion; X. Leroy; F. Lapègue; A. Drizenko; J.-P. Francke; A. Cotten

2002-01-01

417

In vitro screening of Fe(2+) -chelating effect by a Fenton's reaction-luminol chemiluminescence system.  

PubMed

In vitro screening of a Fe(2+) -chelating effect using a Fenton's reaction-luminol chemiluminescence (CL) system is described. The luminescence between the reactive oxygen species generated by the Fenton's reaction and luminol was decreased on capturing Fe(2+) using a chelator. The proposed method can prevent the consumption of expensive seed compounds (drug discovery candidates) owing to the high sensitivity of CL detection. Therefore, the assay could be performed using small volumes of sample solution (150??L) at micromolar concentrations. After optimization of the screening conditions, the efficacies of conventional chelators such as ethylenediaminetetraacetic acid (EDTA), diethylentriaminepentaacetic acid (DETAPAC), deferoxamine, deferiprone and 1,10-phenanthroline were examined. EC50 values for these compounds (except 1,10-phenanthroline) were in the range 3.20?±?0.87 to 9.57?±?0.64??M (n?=?3). Rapid measurement of the Fe(2+) -chelating effect with an assay run time of a few minutes could be achieved using the proposed method. In addition, the specificity of the method was discussed. Copyright © 2014 John Wiley & Sons, Ltd. PMID:24403191

Wada, Mitsuhiro; Komatsu, Hiroaki; Ikeda, Rie; Aburjai, Talal A; Alkhalil, Suleiman M; Kuroda, Naotaka; Nakashima, Kenichiro

2014-11-01

418

Ab initio design of chelating ligands relevant to Alzheimer's disease: influence of metalloaromaticity.  

PubMed

Evidence supporting the role of metal ions in Alzheimer's disease (AD) has rendered metal ion chelation as a promising therapeutic treatment. The rational design of efficient chelating ligands requires, however, a good knowledge of the electronic and molecular structure of the complexes formed. In the present work, the coordinative properties of a set of chelating ligands toward Cu(II) have been analyzed by means of DFT(B3LYP) calculations. Special attention has been paid to the aromatic behavior of the metalated rings of the complex and its influence on the chelating ability of the ligand. Ligands considered have identical metal binding sites (through N/O coordination) and only differ on the kind and size of the aromatic moieties. Results indicate that there is a good correlation between the stability constants (log ?(2)) and the degree of metalloaromaticity determined through the I(NG) and HOMA indices; that is, the higher the metalloaromaticity, the larger the log ?(2) value. MOs and aromaticity descriptors confirm that present complexes exhibit Möbius metalloaromaticity. Detailed analysis of the nature of the Cu(II)-ligand bonding, performed through an energy decomposition analysis, indicates that ligands with less aromatic moieties have the negative charge more localized in the metalated ring, thus increasing their ?-donor character and the metalloaromaticity of the complexes they form. PMID:21699142

Rimola, Albert; Alí-Torres, Jorge; Rodríguez-Rodríguez, Cristina; Poater, Jordi; Matito, Eduard; Solà, Miquel; Sodupe, Mariona

2011-11-17

419

Growth and Decay: An Experiment Demonstrating Radioactivity Relationships and Chelate Solvent Extraction Separations.  

ERIC Educational Resources Information Center

The separation of lead and bismuth by chelate solvent extraction is of interest because of the simplicity which the use of radiotracers allows in its demonstration. Theoretical background information, procedures, materials needed, and typical results are provided for an experiment involving the extraction. (JN)

Downey, D. M.; And Others

1984-01-01

420

Copper chelation selectively kills colon cancer cells through redox cycling and generation of reactive oxygen species  

PubMed Central

Background Metals including iron, copper and zinc are essential for physiological processes yet can be toxic at high concentrations. However the role of these metals in the progression of cancer is not well defined. Here we study the anti-tumor activity of the metal chelator, TPEN, and define its mechanism of action. Methods Multiple approaches were employed, including cell viability, cell cycle analysis, multiple measurements of apoptosis, and mitochondrial function. In addition we measured cellular metal contents and employed EPR to record redox cycling of TPEN–metal complexes. Mouse xenografts were also performed to test the efficacy of TPEN in vivo. Results We show that metal chelation using TPEN (5?M) selectively induces cell death in HCT116 colon cancer cells without affecting the viability of non-cancerous colon or intestinal cells. Cell death was associated with increased levels of reactive oxygen species (ROS) and was inhibited by antioxidants and by prior chelation of copper. Interestingly, HCT116 cells accumulate copper to 7-folds higher levels than normal colon cells, and the TPEN-copper complex engages in redox cycling to generate hydroxyl radicals. Consistently, TPEN exhibits robust anti-tumor activity in vivo in colon cancer mouse xenografts. Conclusion Our data show that TPEN induces cell death by chelating copper to produce TPEN-copper complexes that engage in redox cycling to selectively eliminate colon cancer cells. PMID:25047035

2014-01-01

421

Spectroscopy, modeling and computation of metal chelate solubility in supercritical CO{sub 2}  

SciTech Connect

The overall objectives of this project were to gain a fundamental understanding of the solubility and phase behavior of metal chelates in supercritical CO{sub 2}. Extraction with CO{sub 2} is an excellent way to remove organic compounds from soils, sludges and aqueous solutions, and recent research has demonstrated that, together with chelating agents, it is a viable way to remove metals, as well. In this project the authors sought to gain fundamental knowledge that is vital to computing phase behavior, and modeling and designing processes using CO{sub 2} to separate organics and metal compounds from DOE mixed wastes. The overall program was a comprehensive one to measure, model and compute the solubility of metal chelate complexes in supercritical CO{sub 2} and CO{sub 2}/cosolvent mixtures. Through a combination of phase behavior measurements, spectroscopy and the development of a new computational technique, the authors have achieved a completely reliable way to model metal chelate solubility in supercritical CO{sub 2} and CO{sub 2}/co-contaminant mixtures. Thus, they can now design and optimize processes to extract metals from solid matrices using supercritical CO{sub 2}, as an alternative to hazardous organic solvents that create their own environmental problems, even while helping in metals decontamination.

J. F. Brennecke; M. A. Stadtherr

1999-12-10

422

Trace element analysis of natural water samples by neutron activation analysis with chelating resin  

Microsoft Academic Search

Procedures are described to preconcentrate the trace elements in 100, 200, or 500 mL of natural water into a solid sample of approximately half a gram by using a chelating resin. These procedures are applicable to both freshwater and seawater and leave the transition metals and other elements of interest essentially free from the alkali metals, the alkaline earth metals,

R. R. Greenberg; H. M. Kingston

1983-01-01

423

Chelation ion chromatography of metal ions using high performance substrates dynamically modified with heterocyclic carboxylic acids  

Microsoft Academic Search

This study shows that stable high efficiency metal chelating substrates can be formed from neutral stationary phases by dynamically loading with low molecular weight complexing agents present in the mobile phase. Three complexing pyridine carboxylic acids, namely, picolinic, dipicolinic and quinaldic acids were used to dynamically coat both a C18silica gel and a polystyrene resin and the separation performance compared

M. J Shaw; S. J Hill; P Jones

1999-01-01

424

Study on the Selectivity of Benzoylation of Metal Chelates of Sucrose  

Microsoft Academic Search

A study of the selectivity of metal chelate-directed benzoylation of sucrose dianion, relative to unchelated sucrose anion, was conducted as part of a study on new synthetic approaches to the high-potency sweetener sucralose. Ionic complexes of sucrose with various metal ions were prepared in DMF and the resulting complexes reacted at low temperature with benzoic anhydride. Cobalt and manganese salts

Juan L. Navia; Richard A. Roberts; Robert E. Wingard Jr

1995-01-01

425

In vitro growth inhibition of mastitis causing bacteria by phenolics and metal chelators  

Microsoft Academic Search

Antimicrobial activities of three phenolic compounds and four metal chelators were tested at 0, 250, 500, and 1000 ppm in vitro against four major mastitis-causing bacteria, Streptococcus agalactiae, Staphylococcus aureus, Klebsiella pnuemoniae, and Escherichia coli. Overall, butylated hydroxyanisole and tert-butylhydroquinone showed the greatest antimicrobial activity. These phenolics were bactericidal at 250 to 500 ppm against all four bacteria tested. The

B. P. Chew; L. W. Tjoelker; T. S. Tanaka

1985-01-01

426

Self-assembled thin films of semiconducting zinc (II) and terbium (III) chelates for optoelectronics applications  

NASA Astrophysics Data System (ADS)

Metallorganic thin films with semi-conducting properties, based on zinc chelation with 8,8'-dihydroxy-5,5'-bisquinoline were fabricated via a reactive self-assembly technique. An accelerated film growth was observed with assemblies done using organo-zinc (ZnEt 2, Zn(CH3COO)2, and Zn(CF3COO) 2) salts, compared to a slower growth with ZnCl2, and ZnBr 2. The film growth properties were characterized through various spectroscopic and microscopy techniques. The accelerated growth observed is presently explained via a secondary self-assembly process of labile zinc-precursors stabilized within cavities formed in the primary structure. Light emitting diodes were fabricated from the zinc chelates, which presently exhibit limited quantum efficiencies. A metal-chelating polyurethane-urea based on 2,6-diaminopyridine and 1,6-diisocyanato hexane and chain extended with polyethylene oxide was assembled with a terbium salt to produce luminescent multilayer chelate films, via a novel anhydrous layer-by-layer self-assembly process. UV-Vis spectroscopy and spectroscopic ellipsometry indicate a monotonic but complex increase in film thickness relative to the number of layers. These assemblies show a strong green emission, characteristic of luminescent terbium (Tb3+) chelates. Light emitting diodes from a terbium chelating fully conjugated polyurea, poly(1,4-phenylene-2,6-pyridylurea) were fabricated and electrical properties characterized. The photo-physical properties of these metal chelating pyridyl-based aromatic were also investigated. In their solution state and upon prolonged exposure to 365 nm UV-radiation, these low and high molecular weight compounds were found to cleave the urea linkage nearly quantitatively, generating corresponding amine terminated subunits and CO2 NMR, UV/Vis absorption and fluorescence spectroscopy characterization of the photo-cleavage processes were delineated as a function of UV dose, O2 and water. Experimental results support a light-assisted hydrolysis of the urea bond as the most plausible photo-cleavage mechanism.

Mwaura, Jeremiah Kamau

427

Predictors of dimercaptosuccinic acid chelatable lead and tibial lead in former organolead manufacturing workers  

PubMed Central

OBJECTIVES: To identify predictors of tibial and dimercaptosuccinic acid (DMSA) chelatable lead in 543 organolead manufacturing workers with past exposure to organic and inorganic lead. METHODS: In this cross sectional study, tibial lead (by 109Cd K-shell x ray fluorescence), DMSA chelatable lead (4 hour urinary lead excretion after oral administration of 10 mg/kg), and several exposure measures were obtained on study participants, mean (SD) age 57.6 (7.6) years. RESULTS: Tibial lead concentrations ranged from -1.6 to 52.0 micrograms lead/g bone mineral, with a mean (SD) of 14.4 (9.3) micrograms/g. DMSA chelatable lead ranged from 1.2 to 136 micrograms, with a mean (SD) of 19.3 (17.2) micrograms. In a multiple linear regression model of tibial lead, age (p < 0.01), duration of exposure (p < 0.01), current (p < 0.01) and past (p = 0.05) cigarette smoking, and diabetes (p = 0.01) were all independent positive predictors, whereas height (p = 0.03), and exercise inducing sweating (p = 0.04) were both negative predictors. The final regression model accounted for 31% of the variance in tibial lead concentrations; 27% was explained by age and duration of exposure alone. DMSA chelatable lead was directly associated with tibial lead (p = 0.01), cumulative exposure to inorganic lead (y.microgram/m3, p = 0.01), current smoking (p < 0.01), and weight (p < 0.01), and negatively associated with diabetes (p = 0.02). The final model accounted for 11% of the variance in chelatable lead. When blood lead was added to this model of DMSA chelatable lead, tibial lead, cumulative exposure to inorganic lead, and diabetes were no longer significant; blood lead accounted for the largest proportion of variance (p < 0.001); and the total model r2 increased to 19%. CONCLUSIONS: The low proportions of variance explained in models of both tibial and chelatable lead suggest that other factors are involved in the deposition of lead in bone and soft tissue. In epidemiological studies of the health effects of lead, evaluation of associations with both these measures may allow inferences to be made about whether health effects are likely to be recent, and thus potentially reversible, or chronic, and thus possibly irreversible. The data also provide direct evidence that in men the total amount of lead in the body that is bioavailable declines with age.   PMID:10341742

Schwartz, B. S.; Stewart, W. F.; Todd, A. C.; Links, J. M.

1999-01-01

428

f-Element Ion Chelation in Highly Basic Media - Final Report  

SciTech Connect

A large body of data has been collected over the last fifty years on the chemical behavior of f-element ions. The ions undergo rapid hydrolysis reactions in neutral or basic aqueous solutions that produce poorly understood oxide-hydroxide species; therefore, most of the fundamental f-element solution chemistry has allowed synthetic and separations chemists to rationally design advanced organic chelating ligands useful for highly selective partitioning and separation of f-element ions from complex acidic solution matrices. These ligands and new examples under development allow for the safe use and treatment of solutions containing highly radioactive species. This DOE/EMSP project was undertaken to address the following fundamental objectives: (1) study the chemical speciation of Sr and lanthanide (Ln) ions in basic aqueous media containing classical counter anions found in waste matrices; (2) prepare pyridine N-oxide phosphonates and phosphonic acids that might act as selective chelator s for Ln ions in model basic pH waste streams; (3) study the binding of the new chelators toward Ln ions and (4) examine the utility of the chelators as decontamination and dissolution agents under basic solution conditions. The project has been successful in attacking selected aspects of the very difficult problems associated with basic pH solution f-element waste chemistry. In particular, the project has (1) shed additional light on the initial stages of Ln ion sol-gel-precipitate formulation under basic solution conditions; (2) generated new families of pyridine phosphonic acid chelators; (3) characterized the function of the chelators and (4) examined their utility as oxide-hydroxide dissolution agents. These findings have contributed significantly to an improved understanding of the behavior of Ln ions in basic media containing anions found in typical waste sludges as well as to the development of sludge dissolution agents. The new chelating reagents are easily made and could be prepared in quantities suitable for large scale decontamination and dissolution processes involving sludges. Further studies will be required to assess specific performance in actinide ion bearing wastes.

Paine, R.T.

2000-12-12

429

Transition metal-chelating surfactant micelle templates for facile synthesis of mesoporous silica nanoparticles  

SciTech Connect

Highly ordered mesoporous silica nanoparticles with tunable morphology and pore-size are prepared by the use of a transition metal-chelating surfactant micelle complex using Co{sup 2+}, Ni{sup 2+}, Cu{sup 2+}, and Zn{sup 2+} ions. These metal ions formed a metal-P123 micelle complex in an aqueous solution, while the metal ions are chelated to the hydrophilic domain such as the poly(ethylene oxide) group of a P123 surfactant. The different complexation abilities of the utilized transition metal ions play an important role in determining the formation of nano-sized ordered MSNs due to the different stabilization constant of the metal-P123 complex. Consequently, from a particle length of 1700 nm in the original mesoporous silica materials, the particle length of ordered MSNs through the metal-chelating P123 micelle templates can be reduced to a range of 180-800 nm. Furthermore, the variation of pore size shows a slight change from 8.8 to 6.6 nm. In particular, the Cu{sup 2+}-chelated MSNs show only decreased particle size to 180 nm. The stability constants for the metal-P123 complex are calculated on the basis of molar conductance measurements in order to elucidate the formation mechanism of MSNs by the metal-chelating P123 complex templates. In addition, solid-state {sup 29}Si, {sup 13}C-NMR and ICP-OES measurements are used for quantitative characterization reveal that the utilized metal ions affect only the formation of a metal-P123 complex in a micelle as a template. - Graphical abstract: Metal-chelating surfactant micelle templates support a simple and facile preparations of size-tunable ordered MSNs. Black-Small-Square Highlights: Black-Right-Pointing-Pointer Facile preparation of mesoporous silica nanoparticles (MSNs) was achieved by metal-chelating surfactant micelle complex using Co{sup 2+}, Ni{sup 2+}, Cu{sup 2+}, and Zn{sup 2+} ions. Black-Right-Pointing-Pointer Different complexation of metal ions plays an important role in determining the formation of nano-sized ordered MSNs. Black-Right-Pointing-Pointer Systematic characterization of the synthesized materials was achieved by solid-state {sup 29}Si and {sup 13}C-NMR techniques, BET, FT-IR, and XPS. Black-Right-Pointing-Pointer Stability constants for the metal-P123 complex are calculated on the basis of molar conductance measurements in order to elucidate the formation mechanism.

Lee, Hye Sun [Korea Institute of Ceramic Engineering and Technology, Seoul 153-801 (Korea, Republic of); Department of Materials Science and Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of); Kim, Won Hee; Lee, Jin Hyung [Korea Institute of Ceramic Engineering and Technology, Seoul 153-801 (Korea, Republic of); Choi, Doo Jin [Department of Materials Science and Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of); Jeong, Young-Keun [National Core Research Center for Hybrid Materials Solution, Pusan National University, Pusan 609-735 (Korea, Republic of); Chang, Jeong Ho, E-mail: jhchang@kicet.re.kr [Korea Institute of Ceramic Engineering and Technology, Seoul 153-801 (Korea, Republic of)

2012-01-15

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Synthesis and radiolabeling of chelator-RNA aptamer bioconjugates with copper-64 for targeted molecular imaging  

PubMed Central

Ribonucleic acid (RNA) aptamers with high affinity and specificity for cancer-specific cell-surface antigens are promising reagents for targeted molecular imaging of cancer using positron emission tomography (PET). For this application,