Sample records for ferrous bisglycinate chelate

  1. Safety Evaluation of Ferrous Bisglycinate Chelate

    Microsoft Academic Search

    R. B Jeppsen; J. F Borzelleca

    1999-01-01

    Ferrous bisglycinate chelate (FerrochelTMFerrochel is a proprietary trademake of Albion Laboratories, Inc.) is a highly stable chelate that can be added to most foods. Data from human and animal studies indicate that the ferrous iron is readily bioavailable with fewer side-effects than the more commonly used iron salts. The acute oral LD50 for male and female Sprague–Dawley (S-D) rats is

  2. Safety evaluation of ferrous bisglycinate chelate.

    PubMed

    Jeppsen, R B; Borzelleca, J F

    1999-07-01

    Ferrous bisglycinate chelate (Ferrochel) is a highly stable chelate that can be added to most foods. Data from human and animal studies indicate that the ferrous iron is readily bioavailable with fewer side-effects than the more commonly used iron salts. The acute oral LD50 for male and female Sprague-Dawley (S-D) rats is 2800 mg/kg body weight (560 mg/kg body weight iron [confidence limit (CL) 399-786] as the active ingredient). Male and female CD (Sprague Dawley-derived) rats were fed ferrous bisglycinate as a dietary admixture at doses of 0, 100, 250 and 500 mg/kg body weight/day. There were no biologically or statistically significant dose-related differences between the control and treated animals with respect to body weight gain, food consumption, food efficiency, behavioural effects, clinical chemistries, haematology, absolute and relative organ weights, or gross and microscopic findings. Hepatic non-heme iron concentrations were elevated, indicating that the ferrous iron had been absorbed. The no-observed-adverse-effect level (NOAEL) was 500 mg/kg body weight/day, the highest dose tested. PMID:10496373

  3. Treatment of mild non-chemotherapy-induced iron deficiency anemia in cancer patients: comparison between oral ferrous bisglycinate chelate and ferrous sulfate.

    PubMed

    Ferrari, Paola; Nicolini, Andrea; Manca, Maria Laura; Rossi, Giuseppe; Anselmi, Loretta; Conte, Massimo; Carpi, Angelo; Bonino, Ferruccio

    2012-09-01

    In cancer patients mild-moderate non-chemotherapy-induced iron deficiency anemia (IDA) is usually treated with oral iron salts, mostly ferrous sulfate. In this study, we compare efficacy and toxicity of oral ferrous bisglycinate chelate and ferrous sulfate in cancer patients with mild IDA. Twenty-four patients operated on for solid tumors (10 breast, 12 colorectal, 2 gastric), aged 61±10 years (range 45-75), with non-chemotherapy-induced hemoglobin (Hb) values between 10 and 12 g/dL and ferritin lower than 30 ng/mL were randomized to receive oral ferrous bisglycinate chelate, 28 mg per day for 20 days, and then 14 mg per day for 40 days (12 patients) (A group) or oral ferrous sulphate, 105 mg per day for 60 days (12 patients) (B group). Values of hemoglobin and ferritin obtained at diagnosis, 1 and 2 months from the beginning of treatment were compared. Adverse events (AEs) related to the two treatments were recorded. In the 12 patients treated with ferrous bisglycinate chelate, basal hemoglobin and ferritin values (mean±SD) were 11.6±0.8 g/dL and 16.1±8.0 ng/mL. After 2 months of treatment, they were 13.0±1.4 g/dL and 33.8±22.0 ng/mL, respectively (P=0.0003 and P=0.020). In the group treated with ferrous sulphate, hemoglobin and ferritin mean values were 11.3±0.6 g/dL and 19.0±6.4 ng/mL basally, and 12.7±0.70 g/dL and 40.8±28.1 ng/mL (P<0.0001 and P=0.017) after 2 months of treatment. AEs occurred in six cases. In all these six cases, two (17%) treated with ferrous bisglycinate chelate and four (33%) with ferrous sulphate, toxicity was grade 1. In conclusion, these data suggest that ferrous bisglycinate chelate has similar efficacy and likely lower GI toxicity than ferrous sulphate given at the conventional dose of 105 mg per day for the same time. PMID:22795809

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

    PubMed Central

    2014-01-01

    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

  5. Ferrous bisglycinate content and release in W 1\\/O\\/W 2 multiple emulsions stabilized by protein–polysaccharide complexes

    Microsoft Academic Search

    R. Jiménez-Alvarado; C. I. Beristain; L. Medina-Torres; A. Román-Guerrero; E. J. Vernon-Carter

    2009-01-01

    Ferrous bisglycinate aqueous solution was entrapped in the inner phase (W1) of water-in-oil-in-water (W1\\/O\\/W2) multiple emulsions. The primary ferrous bisglycinate aqueous solution-in-mineral oil (W1\\/O) emulsion contained 15% (w\\/w) ferrous bisglycinate, had a dispersed phase mass fraction of 0.5, and was stabilized with a mixture of Grindsted PGPR 90:Panodan SDK (6:4 ratio) with a total emulsifiers concentration of 5% (w\\/w). This

  6. Toddlers’ acceptance of whole maize meal porridge fortified with Ferrous Bisglycinate

    Microsoft Academic Search

    Adelia C Bovell-Benjamin; Lindsay H Allen; Jean-Xavier Guinard

    1999-01-01

    Consumer acceptance of maize fortified with ferrous bisglycinate (BIS), and with or without the antioxidant BHA, was measured in forty toddlers (6–24 months) and their mothers, as part of a research project investigating the suitability of BIS for use as an iron fortificant in developing countries. Porridge was prepared from unfortified maize (CTRL), or maize meal fortified with 30mg\\/kg iron

  7. The efficacy of ferrous bisglycinate and electrolytic iron as fortificants in bread in iron-deficient school children.

    PubMed

    van Stuijvenberg, Martha E; Smuts, Cornelius M; Wolmarans, Petronella; Lombard, Carl J; Dhansay, Muhammad A

    2006-03-01

    Food fortification is an important long-term strategy for addressing micronutrient deficiencies. Finding the ideal Fe fortification compound, however, remains a challenge. In the present study the effect of ferrous bisglycinate as fortificant in brown bread was compared with that of electrolytic Fe among Fe-deficient school children in a randomised controlled trial. Children (n 160), aged 6-11 years, with serum ferritin <20 microg/l, were randomly assigned to one of three treatment categories: (i) standard unfortified bread; (ii) bread with electrolytic Fe as fortificant; and (iii) bread with ferrous bisglycinate as fortificant. Each child received four slices of bread (120 g) on school days, which supplied an average of 3.66 mg elemental Fe per intervention day for 137 d (2.52 mg/d for 75 d and 5.04 mg/d for 62 d) over a period of 7.5 months. Hb, serum ferritin, serum Fe and transferrin saturation were measured at baseline and at the end of the intervention. Significant treatment effects were observed for Hb (P = 0.013), serum Fe (P = 0.041) and transferrin saturation (P = 0.042) in the ferrous bisglycinate group, but not in the electrolytic Fe group. There were no significant intervention effects for serum ferritin in either treatment group. Overall, ferrous bisglycinate as Fe fortificant in brown bread performed better than electrolytic Fe in a group of Fe-deficient school children over a period of 7.5 months. PMID:16512940

  8. An LC Ion-Pairing Method for the Determination of Fe(II) in Ferrous Bisglycinate Pharmaceutical Formulation

    Microsoft Academic Search

    Danieli Cátia Ceni; Laura Alegria Martins; Andréa Garcia Pereira; Pedro Eduardo Fröehlich; Ana Maria Bergold

    2009-01-01

    A reversed-phase ion-pairing liquid chromatographic method was developed and validated for the assay of Fe(II) in ferrous\\u000a bisglycinate (Fe-bis-gly) capsules using 4-(2-pyridylazo) resorcinol reagent. The analysis was carried out using a Gemini\\u000a RP-18 (150 mm × 4.6 mm I.D., particle size 5 ?m) analytical column; the mobile phase consisted of a mixture of acetonitrile–water\\u000a (28:72 v\\/v) containing 1 mM tetrabutylammonium hydrogensulfate and 1% phosphate buffer (pH

  9. Effect of Long-term Fortification of Whey Drink With Ferrous Bisglycinate on Anemia Prevalence in Children and Adolescents From Deprived Areas in Londrina, Paraná, Brazil

    Microsoft Academic Search

    Lúcia H. S Miglioranza; Tiemi Matsuo; Glenys M Caballero-Córdoba; Jane B Dichi; Edílson S Cyrino; Ivonete B. N Oliveira; Mary S Martins; Nívea M Polezer; Isaias Dichi

    2003-01-01

    ObjectiveFortification of food with iron is considered the best sustainable way of preventing iron deficiency when an appropriate diet is not available. The most difficult challenge is to find the ideal combination of iron fortification compound and food vehicle. We investigated the effect of cheese whey drink with 15% of frozen strawberry fortified with ferrous bisglycinate on hemoglobin values in

  10. Iron bioavailability in humans from breakfasts enriched with iron bis-glycine chelate, phytates and polyphenols.

    PubMed

    Layrisse, M; García-Casal, M N; Solano, L; Barón, M A; Arguello, F; Llovera, D; Ramírez, J; Leets, I; Tropper, E

    2000-09-01

    This study was conducted to determine the bioavailability of iron amino acid chelate (ferrochel) added to fortify breads prepared from either precooked corn flour or white wheat flour + cheese and margarine compared with the same basal breakfast enriched with either ferrous sulfate or iron-EDTA. The inhibitory effect of phytate and polyphenols on iron absorption from ferrochel was also tested. A total of 74 subjects were studied in five experiments. Iron absorption from ferrochel was about twice the absorption from ferrous sulfate (P: < 0.05). When ferrous sulfate and ferrochel were administered together or in different meals, absorption from ferrochel was about twice the absorption from ferrous sulfate (P: < 0.05). Polyphenols present in coffee and tea inhibited iron absorption in a dose-dependent manner. American-type coffee did not modify iron absorption significantly, whereas both espresso-type coffee and tea reduced iron absorption from ferrochel by 50% (P: < 0. 05). Ferrochel partially prevented the inhibitory effect of phytates. Because of its high solubility in aqueous solutions even at pH 6, its low interactions with food and high absorption, ferrochel is a suitable compound for food fortification. PMID:10958812

  11. Determination of the iron state in ferrous iron containing vitamins and dietary supplements: Application of Mössbauer spectroscopy

    Microsoft Academic Search

    M. I. Oshtrakh; O. B. Milder; V. A. Semionkin

    2006-01-01

    Determination of the iron state in commercially manufactured iron containing vitamins and dietary supplements is important for evaluation of pharmaceuticals quality. Mössbauer (nuclear gamma-resonance) spectroscopy was used for analyzing the iron state in commercial pharmaceutical products containing ferrous fumarate (FeC4H2O4), ferrous sulfate (FeSO4), ferrous bisglycinate chelate (Ferrochel®) and ferrous iron (hydrolyzed protein chelate). Mössbauer parameters and the iron states were

  12. Determination of the iron state in ferrous iron containing vitamins and dietary supplements: application of Mössbauer spectroscopy.

    PubMed

    Oshtrakh, M I; Milder, O B; Semionkin, V A

    2006-03-18

    Determination of the iron state in commercially manufactured iron containing vitamins and dietary supplements is important for evaluation of pharmaceuticals quality. Mössbauer (nuclear gamma-resonance) spectroscopy was used for analyzing the iron state in commercial pharmaceutical products containing ferrous fumarate (FeC(4)H(2)O(4)), ferrous sulfate (FeSO(4)), ferrous bisglycinate chelate (Ferrochel) and ferrous iron (hydrolyzed protein chelate). Mössbauer parameters and the iron states were determined for iron compounds in the studied pharmaceuticals. Various ferric and ferrous impurities were found in all of the commercial products. The quantities of ferric impurities exceeded the FDA limitation of 2% in products containing ferrous fumarate. The quantities of ferric impurities exceeded 58% and 30% in products containing ferrous bisglycinate chelate and ferrous iron (hydrolyzed protein chelate), respectively. The presence of ferrous and ferric impurities was not related to the ageing of the vitamins and dietary supplements. Two pharmaceutical products contained major iron compounds, the Mössbauer parameters of which did not correspond to the ferrous fumarate or ferrous bisglycinate chelate claimed by the manufacturer. PMID:16280229

  13. Effect of iron chelates on oil–water interface, stabilized by milk proteins: The role of phosphate groups and pH. Prediction of iron transfer from aqueous phase toward fat globule surface by changes of interfacial properties

    Microsoft Academic Search

    Tatiana Guzun-Cojocaru; Philippe Cayot; Camille Loupiac; Eliane Cases

    2010-01-01

    Iron incorporated into food systems induces oxidation and precipitation. The consequences are reduced bioavailability and a functional modification of other food components such as proteins. The iron-chelates such as ferrous bisglycinate represent a possibility to avoid side effects, since the iron is protected. The aim of this study is to investigate the effects of iron-chelates compounds on the properties of

  14. Ferrus Calcium Citrate Is Absorbed Better Than Iron Bisglycinate in Patients with Crohn's Disease, but Not in Healthy Controls

    Microsoft Academic Search

    Irit Chermesh; Ada Tamir; Alain Suissa; Rami Eliakim

    2006-01-01

    Our purpose was to compare the absorption of iron bisglycinate and ferrous calcium citrate in volunteers using an oral iron tolerance test. Twenty volunteers, 10 healthy controls and 10 with stable Crohn's disease, agreed to participate in the study. All were given 50 mg of elemental iron as iron bisglycinate or ferrous calcium citrate. Serum iron levels were monitored for 4 hr.

  15. Ferrus calcium citrate is absorbed better than iron bisglycinate in patients with Crohn's disease, but not in healthy controls.

    PubMed

    Chermesh, Irit; Tamir, Ada; Suissa, Alain; Eliakim, Rami

    2006-05-01

    Our purpose was to compare the absorption of iron bisglycinate and ferrous calcium citrate in volunteers using an oral iron tolerance test. Twenty volunteers, 10 healthy controls and 10 with stable Crohn's disease, agreed to participate in the study. All were given 50 mg of elemental iron as iron bisglycinate or ferrous calcium citrate. Serum iron levels were monitored for 4 hr. After a week, each received the other regimen. Using the area under the curve as indicator, the oral iron absorption test revealed that absorption of iron post-ingestion of ferrous calcium citrate was better than after ingestion of iron bisglycinate for the group as a whole (P < 0.03). Volunteers with Crohn's disease absorbed ferrous calcium citrate better than iron bisglycinate (P=0.005). No difference was noted in the absorption of either preparation by healthy volunteers. Ferrus calcium citrate is apparently more effective than iron bisglycinate in patients with Crohn's disease. PMID:16642425

  16. Inhibition of iron uptake from iron salts and chelates by divalent metal cations in intestinal epithelial cells.

    PubMed

    Yeung, Chi Kong; Glahn, Raymond P; Miller, Dennis D

    2005-01-12

    Iron chelates, namely, ferrous bisglycinate and ferric EDTA, are promising alternatives to iron salts for food fortification. The objectives of this study were to compare iron uptake from radiolabeled ferrous sulfate, ferrous ascorbate, ferrous bisglycinate, ferric chloride, ferric citrate, and ferric EDTA by Caco-2 cells with different iron status and in the presence of divalent metal cations. Iron-loaded Caco-2 cells, with reduced DMT-1 and elevated HFE mRNA levels, down-regulated uptake from ferrous ascorbate and bisglycinate but not from ferric compounds. Nevertheless, iron uptake from all compounds was markedly inhibited in the presence of 100-fold molar excess of Co2+ and Mn2+ cations, with ferrous compounds showing a greater percent reduction. Our results suggest that ferrous iron is the predominant form of iron taken up by intestinal epithelial cells and the DMT-1 pathway is the major pathway for uptake. Iron uptake from chelates appears to follow the same pathway as uptake from salts. PMID:15631519

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

    Microsoft Academic Search

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

    2008-01-01

    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

  18. Persulfate oxidation for in situ remediation of TCE. II. Activated by chelated ferrous ion

    Microsoft Academic Search

    Chenju Liang; Clifford J Bruell; Michael C Marley; Kenneth L Sperry

    2004-01-01

    In situ chemical oxidation (ISCO) is a technique used to remediate contaminated soil and groundwater systems. It has been postulated that sodium persulfate (Na2S2O8) can be activated by transition metal ions such as ferrous ion (Fe2+) to produce a powerful oxidant known as the sulfate free radical (SO4?) with a redox potential of 2.6 V, which can potentially destroy organic

  19. Strategies for utilizing ferrous*EDTA chelate as an additive in combined SO sub 2 /NO sub x aqueous scrubbing systems

    SciTech Connect

    Medelsohn, M.H.; Harkness, J.B.L.

    1990-01-01

    Ferrous*EDTA chelate has been found to be an effective scrubbing agent for nitric oxide gas. A major problem encountered in its practical application is that that ferrous ion oxidizes in solution to the ferric species, thus decreasing the NO{sub x} removal of the scrubbing solution. This paper discusses three strategies for overcoming this problem. Dow Chemical has studied the use of an electrolytic cell to reduce ferric ions to the corresponding ferrous species. Workers at the Pittsburgh Energy Technology Center have studied in situ bisulfite reduction of ferric ions to ferrous ions at elevated temperature (70{degrees}C). We have studied NO{sub x} removal from simulated flue gas mixtures under various oxidizing conditions and have found that addition of an organic, polyphenolic compound to an aqueous scrubbing solution containing Fe(II)*EDTA leads to a sustained NO{sub x} removal significantly higher than was found without the secondary additive. The improved performance of Fe(II)*EDTA under these conditions is attributed to the known capabilities of these organic compounds to both inhibit oxidation by dissolved oxygen and to rapidly reduce any ferric ions back to the original ferrous species. Advantages of a NO{sub x}-control process based upon an additive in an SO{sub 2}-control chemistry over serial processes are discussed. 10 refs., 6 figs.

  20. Analysis of the iron state in iron containing vitamins and dietary supplements by Mössbauer spectroscopy

    Microsoft Academic Search

    M. I. Oshtrakh; O. B. Milder; V. A. Semionkin

    2004-01-01

    An analysis of iron in some commercial products of vitamins and dietary supplements containing ferrous fumarate, ferrous bisglycinate chelate (Ferrochel®) and ferrous sulfate was made by Mössbauer spectroscopy. Various ferric and ferrous impurities were found. Two vitamin products contained major iron compounds that did not correspond to ferrous fumarate or ferrous bisglycinate chelate announced by the manufacturer.

  1. FERROUS GLYCINATE (PROCESSED WITH CITRIC ACID) First draft prepared by

    Microsoft Academic Search

    Gary Williams

    1. EXPLANATION The call for data for the sixty-first meeting referred to this substance as ferrous bisglycinate. The Committee decided that this name did not accurately describe the substance being evaluated and therefore agreed that it should be referred to as \\

  2. Mössbauer Spectroscopy of Iron Containing Vitamins and Dietary Supplements

    Microsoft Academic Search

    M. I. Oshtrakh; O. B. Milder; V. A. Semionkin

    2004-01-01

    Mssbauer spectroscopy was used to study various industrial samples of vitamins containing ferrous fumarate and ferrous bisglycinate\\u000a chelate (Ferrochel) and dietary supplements containing ferrous sulfate. The presence of small quantities of various ferric impurities was found.\\u000a Two vitamins contained major iron compounds that did not correspond to ferrous fumarate and ferrous bisglycinate chelate.

  3. Mössbauer Spectroscopy of Iron Containing Vitamins and Dietary Supplements

    Microsoft Academic Search

    M. I. Oshtrakh; O. B. Milder; V. A. Semionkin

    2004-01-01

    Mössbauer spectroscopy was used to study various industrial samples of vitamins containing ferrous fumarate and ferrous bisglycinate chelate (Ferrochel®) and dietary supplements containing ferrous sulfate. The presence of small quantities of various ferric impurities was found. Two vitamins contained major iron compounds that did not correspond to ferrous fumarate and ferrous bisglycinate chelate.

  4. Toxicology and safety of Ferrochel and other iron amino acid chelates.

    PubMed

    Jeppsen, R B

    2001-03-01

    Iron is estimated to be deficient in the diets of one fifth of the world's population. Iron is commonly provided as a supplemental nutrient in industrialized countries for uses of choice. In other countries of the world, it may be required as an overt addition to the diet to prevent iron deficiency. This may be accomplished through fortification of a common food. As a micronutrient, iron has a relatively narrow range of safety--whether given as a supplement or fortificant, it must be in a high enough dose to be appreciably absorbed, but low enough to avoid toxicity. This concern can be ameliorated by careful choice of the form of iron administered. A source of iron which has proven to be highly bioavailable, yet regulated by dietary need, is iron chelated with amino acids. The structural integrity and longevity of these compounds have been proven by valid chemical and instrumental tests. Proofs of safety of iron amino acid chelate in the dietary administration of iron to swine in both multigenerational and longevity studies are reported. Formal tests of toxicity utilizing ferrous bisglycinate chelate (Ferrochel) carried out in accordance to US-FDA guidelines are also summarized. Ferrochel has been demonstrated to have a No Observable Adverse Effect Level (NOAEL) of at least 500 mg per kg rat body weight, the highest dose tested. This and other results of the detailed toxicity test, as well as other tests of safety and efficacy, have resulted in the US-FDA acknowledging that this product is Generally Recognized As Safe (GRAS) under its approved conditions of use as a source of iron for food enrichment and fortification purposes. PMID:11688078

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

    PubMed

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

    2012-01-12

    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 Fe(2+) with a dissociation constant of ?10(-19)?M, with much weaker binding to Fe(3+) and other transition metals. HQBA inhibited proliferation of multiple cell lines in culture, and blocked the progression of established spontaneous cancers in two distinct genetically engineered mouse models of mammary cancer, MMTV-Wnt1 and MMTV-PyMT mice, without overt toxicity. HQBA may inhibit an iron-dependent factor that regulates cell-type-specific ?-catenin-driven transcription. It inhibits cancer cell proliferation independently of its effect on ?-catenin signaling, as it works equally well in MMTV-PyMT tumors and diverse ?-catenin-independent cell lines. HQBA is a promising specific intracellular Fe(2+) chelator with activity against spontaneous mouse mammary cancers. PMID:21666721

  6. Effect of iron chelators on placental uptake and transfer of iron in rat

    Microsoft Academic Search

    C. T. Wong; H. J. McArdle; E. H. Morgan

    1987-01-01

    The uptake of radiolabeled transferrin and iron by the rat placenta has been studied using two approaches. The first involved injection of a ferrous or ferric iron chelator followed by injection of label. Neither chelator decreased the amount of labelled transferrin in the placenta after 2-h incubation and only bipyridine, a ferrous iron chelator, inhibited iron transport to the fetus.

  7. 21 CFR 73.165 - Ferrous lactate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...2010-04-01 2010-04-01 false Ferrous lactate. 73.165 Section 73.165 Food...CERTIFICATION Foods § 73.165 Ferrous lactate. (a) Identity. The color additive ferrous lactate is the ferrous lactate defined in §...

  8. In vitro characteristics of 1-phenyl-3-methyl-4-acylpyrazol-5-ones iron chelators.

    PubMed

    Filipský, Tomáš; Mlad?nka, P?emysl; Macáková, Kate?ina; Hrdina, Radomír; Saso, Luciano; Marchetti, Fabio; Pettinari, Claudio

    2012-01-01

    Iron chelators represent a group of structurally different compounds sharing the ability of iron binding. The group has been evolving in recent years mainly due to novel experimental indications associated with variable requirements for iron chelators. A group of synthetic 1-phenyl-3-methyl-4-acyl-pyrazol-5-ones has been known for many years but data on their potential biological activity are rather limited. In this study, we analysed a series of these compounds for their iron-chelating properties as well as for their effects on iron based Fenton chemistry. For the former ferrozine spectrophotometric method and for the latter HPLC method with salicylic acid were used. All of the tested compounds were very efficient ferric chelators but their ferrous-chelating effects differed according to the acyl substitution. Notwithstanding various ferrous chelation activities, the individual Fe(2+)-affinities were not significantly different through pathophysiologically relevant pH conditions and some of the tested substances were more potent ferrous chelators at pH 4.5 than clinically used standard deferoxamine. Of particular interest is H(2)QpyQ /2,6-bis[4(1-phenyl-3-methylpyrazol-5-one)carbonyl]pyridine/ which iron-chelating affinity increased when pH was decreasing. In spite of ferrous chelation differences, most of the tested acylpyrazolones were similarly active powerful inhibitors of Fenton chemistry as deferoxamine. Conclusively, acylpyrazolones are efficient iron chelators and H(2)QpyQ may represent a prototype of novel specific chelators designated particularly for chelation at acidic conditions. PMID:21986369

  9. [Effectiveness of different iron supplementation strategies on hemoglobin and ferritin levels among schoolchildren in Teresina, Piauí State, Brazil].

    PubMed

    Dos Santos, Marize Melo; Nogueira, Nadir do Nascimento; Diniz, Alcides da Silva

    2007-07-01

    This study evaluated the effectiveness of supplementation with ferrous sulfate and iron bis-glycinate chelate on hemoglobin and serum ferritin levels among schoolchildren (7-11 years) of both sexes. A randomized community-based trial including 138 anemic children (hemoglobin < 11.5 g/dL) was conducted in Teresina, Piauí State, Brazil. Children were assigned to two treatment groups on an individual basis. One group (n = 71) received 40 mg iron as ferrous sulfate once weekly and the other group (n = 67) received 3.8 mg of iron bis-glycinate chelate-enriched cookies, 3x/week, for 8 weeks. The interventions showed a significant increase (p < 0.01) in hemoglobin levels (1.1g/dL) for children who received ferrous sulfate and 0.9 g/dl in those who received iron bis-glycinate chelate, although not significant in the inter-group comparison (p > 0.05). No effect was observed on body iron for either intervention (p > 0.05). Children with depleted iron stores (< 15 ng/mL) at the beginning of interventions showed increased serum ferritin concentrations after 8 weeks (p < 0.01), although no difference between treatments (p > 0.05) was observed. The results confirm the effectiveness of the iron supplementation interventions and corroborate the use of iron salts or ferrous bisglycinate chelate on a weekly basis to overcome iron deficiency and anemia. PMID:17572803

  10. Chlorite removal with ferrous ions

    Microsoft Academic Search

    Sabrina Sorlini; Carlo Collivignarelli

    2005-01-01

    Effective use of chlorine dioxide as an alternative disinfectant in water treatment may require removal of the byproduct chlorite ion (ClO?2). The goal of this research was to investigate the use of ferrous iron (Fe2+) for the chemical reduction of ClO?2 from drinking water in order to define the operating conditions, process efficiency with different pH conditions and organic carbon

  11. Variations of 57Fe hyperfine parameters in medicaments containing ferrous fumarate and ferrous sulfate

    NASA Astrophysics Data System (ADS)

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

    2010-04-01

    Several commercially available medicaments containing ferrous fumarate (FeC4H2O4) and ferrous sulfate (FeSO4), as a source of ferrous iron, were studied using a high velocity resolution Mössbauer spectroscopy. A comparison of the 57Fe hyperfine parameters revealed small variations for the main components in both medicaments indicating some differences in the ferrous fumarates and ferrous sulfates. It was also found that all spectra contained additional minor components probably related to ferrous and ferric impurities or to partially modified main components.

  12. Chelation in Metal Intoxication

    PubMed Central

    Flora, Swaran J.S.; Pachauri, Vidhu

    2010-01-01

    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

  13. The Chelate Effect Redefined.

    ERIC Educational Resources Information Center

    da Silva, J. J. R. Frausto

    1983-01-01

    Discusses ambiguities of the accepted definition of the chelate effect, suggesting that it be defined in terms of experimental observation rather than mathematical abstraction. Indicates that the effect depends on free energy change in reaction, ligand basicity, pH of medium, type of chelates formed, and concentration of ligands in solution. (JN)

  14. Chelates and Stability

    Microsoft Academic Search

    Sameh K. Morcos

    Extracellular gadolinium-based MRI contrast media are all chelates containing Gd ions (Gd3+). Free gadolinium is highly toxic and can cause splenic degeneration, central lobular necrosis of the liver, enzyme inhibition,\\u000a calcium channel blocking and a variety of haematological abnormalities (\\u000a Dawson 1999; \\u000a Desreux and Gilsoul 1999). Therefore, it is crucially important that Gd3+ should be strongly attached to a chelate

  15. Ferrous iron oxidation by anoxygenic phototrophic bacteria

    Microsoft Academic Search

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

    1993-01-01

    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

  16. Effects of some naturally occurring iron ion chelators on in vitro superoxide radical formation

    Microsoft Academic Search

    Tomihiro Hirai; Kazuaki Fukushima; Kazumasa Kumamoto; Hideo Iwahashi

    2005-01-01

    The effects of some naturally occurring iron ion chelators and their derivatives on the electron transfer from ferrous ions\\u000a to oxygen molecules were examined by measuring oxygen consumption rates. Of the compounds examined, quinolinic acid, fusaric\\u000a acid, and 2-pyridinecarboxylic acid repressed the oxygen consumption, whereas chlorogenic acid, caffeic acid, gallic acid,\\u000a catechol l-?-(3,4-dihydroxyphenyl) alanine, and xanthurenic acid accelerated it. Theoretical

  17. Determination of ferrous and ferric iron in aqueous biological solutions.

    PubMed

    Pepper, S E; Borkowski, M; Richmann, M K; Reed, D T

    2010-03-24

    A solvent extraction method was employed to determine ferrous and ferric iron in aqueous samples. Fe(3+) is selectively extracted into the organic phase (n-heptane) using HDEHP (bis(2-ethylhexyl) hydrogen phosphate) and is then stripped using a strong acid. After separation, both oxidation states and the total iron content were determined directly by ICP-MS analysis. This extraction method was refined to allow determination of both iron oxidation states in the presence of strong complexing ligands, such as citrate, NTA and EDTA. The accuracy of the method was verified by crosschecking using a refinement of the ferrozine assay. Presented results demonstrate the ability of the extraction method to work in a microbiological system in the presence of strong chelating agents following the bioreduction of Fe(3+) by the Shewanella alga BrY. Based on the results we report, a robust approach was defined to separately analyze Fe(3+) and Fe(2+) under a wide range of potential scenarios in subsurface environments where radionuclide/metal contamination may coexist with strongly complexing organic contaminants. PMID:20206007

  18. Rigid bifunctional chelating agents

    DOEpatents

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

    2000-02-08

    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.

  19. Rigid bifunctional chelating agents

    DOEpatents

    Sweet, M.P.; Mease, R.C.; Srivastava, S.C.

    1998-07-21

    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.

  20. Rigid bifunctional chelating agents

    DOEpatents

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

    1998-07-21

    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.

  1. 46 CFR 56.60-3 - Ferrous materials.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...SYSTEMS AND APPURTENANCES Materials § 56.60-3 Ferrous materials. (a) Ferrous pipe used for salt water service must be protected against corrosion by hotdip galvanizing or by the use of extra heavy schedule material. (b)...

  2. Stability Studies of Waste Produced in Pilot-Plant Testing using Ferrous-EDTA and Magnesium-Enhanced Lime for Combined Sulfur-Dioxide\\/Nitrogen Oxides Removal

    Microsoft Academic Search

    M. H. Mendelsohn; C. D. Livengood

    1998-01-01

    A pilot-plant-scale study of combined sulfur dioxide\\/nitrogen oxides (SO2\\/NOx) 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® lime process along with Argonne National Laboratory's (ANL's) patented process for combined SO2\\/NOx removal using the chelate ferrous·ethylenediaminetetraacetate (Fe·EDTA). For approximately nine

  3. Uranium (VI) - Chromotropic Acid Chelate

    Microsoft Academic Search

    Samir K. Banerji; Arun K. Dey

    1963-01-01

    DISODIUM- 1:8-dihydroxy naphthalene-3:6-disulphonate (trivial name chromotropic acid-sodium salt)yields coloured lakes with various cations1. Investigations of chelates of chromotropic acid with iron (III)2 and titanium (IV)3,4 have already been made. Sommer et al. have extensively examined chelates of titanium with chromotropic acid and various polyphenols5-7 and have discussed the structure of the metal chelates. The use of chromotropic acid in the

  4. Natural chelates for radionuclide decorporation

    DOEpatents

    Premuzic, E.T.

    1983-08-25

    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.

  5. Chelation of cadmium.

    PubMed Central

    Andersen, O

    1984-01-01

    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

  6. A contemporary microbially maintained subglacial ferrous "ocean".

    PubMed

    Mikucki, Jill A; Pearson, Ann; Johnston, David T; Turchyn, Alexandra V; Farquhar, James; Schrag, Daniel P; Anbar, Ariel D; Priscu, John C; Lee, Peter A

    2009-04-17

    An active microbial assemblage cycles sulfur in a sulfate-rich, ancient marine brine beneath Taylor Glacier, an outlet glacier of the East Antarctic Ice Sheet, with Fe(III) serving as the terminal electron acceptor. Isotopic measurements of sulfate, water, carbonate, and ferrous iron and functional gene analyses of adenosine 5'-phosphosulfate reductase imply that a microbial consortium facilitates a catalytic sulfur cycle. These metabolic pathways result from a limited organic carbon supply because of the absence of contemporary photosynthesis, yielding a subglacial ferrous brine that is anoxic but not sulfidic. Coupled biogeochemical processes below the glacier enable subglacial microbes to grow in extended isolation, demonstrating how analogous organic-starved systems, such as Neoproterozoic oceans, accumulated Fe(II) despite the presence of an active sulfur cycle. PMID:19372431

  7. Antioxidant Potential ofEcklonia cavaon Reactive Oxygen Species Scavenging, Metal Chelating, Reducing Power and Lipid Peroxidation Inhibition

    Microsoft Academic Search

    Mahinda Senevirathne; Soo-Hyun Kim; Nalin Siriwardhana; Jin-Hwan Ha; Ki-Wan Lee; You-Jin Jeon

    2006-01-01

    The antioxidative potential of different fractions (respective organic and aqueous fractions of n-hexane, chloroform and ethyl acetate) of 70% methanol extract of Ecklonia cava(a brown seaweed) was evaluated using 1,1-diphenyl-2-picrylhydrazyl (DPPH), superoxide anion, hydrogen peroxide, hydroxyl radical, nitric oxide, ferrous ion chelating, reducing power and lipid peroxidation inhibition (conjugated diene hydroperoxide and thiobarbituric acid-reactive substances production) assays. The 70% methanol

  8. Evaluating ferrous iron for chlorite ion removal

    Microsoft Academic Search

    Gregory H. Hurst; William R. Knocke

    1997-01-01

    Effective use of chlorine dioxide as an alternative disinfectant in water treatment may require removal of the by-product chlorite ion (Clo??). This study evaluated the effect of alkaline conditions (pH 7-10) and the presence-absence of dissolved oxygen on the ability of ferrous iron [Fe(II)] to reduce Clo??ion to chloride ion (Cl-). Fe(II) dosing from 3.5-4,0 mg Fe(II) per mg Clo??

  9. Removal of copper from ferrous scrap

    DOEpatents

    Blander, M.; Sinha, S.N.

    1990-05-15

    A process for removing copper from ferrous or other metal scrap in which the scrap is contacted with a polyvalent metal sulfide slag in the presence of an excess of copper-sulfide forming additive to convert the copper to copper sulfide which is extracted into the slag to provide a ratio of copper in the slag to copper in the metal scrap of at least about 10.

  10. Removal of copper from ferrous scrap

    DOEpatents

    Blander, M.; Sinha, S.N.

    1987-07-30

    A process for removing copper from ferrous or other metal scrap in which the scrap is contacted with a polyvalent metal sulfide slag in the presence of an excess of copper-sulfide forming additive to convert the copper to copper sulfide which is extracted into the slag to provide a ratio of copper in the slag to copper in the metal scrap of at least about 10.

  11. Removal of copper from ferrous scrap

    DOEpatents

    Blander, Milton (12833 S. 82nd Ct., Palos Park, IL 60464); Sinha, Shome N. (5748 Drexel, 2A, Chicago, IL 60637)

    1990-01-01

    A process for removing copper from ferrous or other metal scrap in which the scrap is contacted with a polyvalent metal sulfide slag in the presence of an excess of copper-sulfide forming additive to convert the copper to copper sulfide which is extracted into the slag to provide a ratio of copper in the slag to copper in the metal scrap of at least about 10.

  12. Novel polycatecholamide chelating agents

    DOEpatents

    Weitl, F.L.; Raymond, K.N.

    1981-08-24

    Novel polybenzamide compounds useful for in vitro or in vivo chelation are described. Formulas of the compounds are given. To prepare them polyamines are reacted with 2,3-dimethoxy benzoyl chloride unsubstituted or substituted with SO/sub 3/H, SO/sub 3/M, NO/sub 2/, CO/sub 2/H or CO/sub 2/M as desired is reacted with a polyamine in an inert solvent then demethylated with BBr/sub 3/ or BCl/sub 3/ in an inert solvent. Where compounds symmetrically substituted on the terminal N's are desired, the polyamine is first reductively alkylated by reaction with an aldehyde or ketone and the resulting Schiff base is hydrogenated.

  13. Polycatecholamide chelating agents

    DOEpatents

    Weitl, F.L.; Raymond, K.N.

    1984-04-10

    Novel polybenzamide compounds useful for in vitro or in vivo chelation are described. The compounds have the formula given in patent. Polyamines are reacted with 2,3-dimethoxy benzoyl chloride unsubstituted or substituted with SO[sub 3]H, SO[sub 3]M, NO[sub 2], CO[sub 2]H or CO[sub 2]M as desired is reacted with a polyamine in an inert solvent then demethylated with BBr[sub 3] or BCl[sub 3] in an inert solvent. Where compounds symmetrically substituted on the terminal N's are desired, the polyamine is first reductively alkylated by reaction with an aldehyde or ketone and the resulting Schiff base is hydrogenated. No Drawings

  14. Polycatecholamide chelating agents

    DOEpatents

    Weitl, Frederick L. (Martinez, CA); Raymond, Kenneth N. (Berkeley, CA)

    1984-01-01

    Novel polybenzamide compounds useful for in vitro or in vivo chelation are described. The compounds have the formula ##STR1## Polyamines are reacted with 2,3-dimethoxy benzoyl chloride unsubstituted or substituted with SO.sub.3 H, SO.sub.3 M, NO.sub.2, CO.sub.2 H or CO.sub.2 M as desired is reacted with a polyamine in an inert solvent then demethylated with BBr.sub.3 or BCl.sub.3 in an inert solvent. Where compounds symmetrically substituted on the terminal N's are desired, the polyamine is first reductively alkylated by reaction with an aldehyde or ketone and the resulting Schiff base is hydrogenated.

  15. Ferrous-activated persulfate oxidation of arsenic(III) and diuron in aquatic system.

    PubMed

    Zhou, Lei; Zheng, Wei; Ji, Yuefei; Zhang, Jinfeng; Zeng, Chao; Zhang, Ya; Wang, Qi; Yang, Xi

    2013-12-15

    In situ chemical oxidation (ISCO) can be an effective technology for the remediation of soil and groundwater polluted by organic and inorganic contaminants. This study investigated the oxidation of arsenic(III) (As(III)) and diuron using ferrous activated persulfate-based ISCO. The results indicated that Fe(II)/persulfate oxidation could be an effective method to oxidize As(III) and diuron. Effects of pH, S2O8(2-) and Fe(II) amounts on the destruction of As(III) and diuron were examined in batch experiments. Acidic conditions favored the removal of As(III) and diuron. Four chelating agents, citric acid (CA), Na2S2O3, diethylene triamine pentaacetic acid (DTPA) and ethylene diamine tetraacetic acid disodium (EDTA-Na2) were used in attempt to maintain the quantity of ferrous ion in solution. In our experiments, CA and Na2S2O3 were found to be more effective than DTPA and EDTA-Na2. Our results also revealed a widely practical prospect of inorganic chelating agent Na2S2O3. Hydroxyl and sulfate radical were determined to play key roles in the oxidation process by using ethanol and tertiary butanol as molecular probes. Oxidation of As(III) yielded As(V) via the electron-transfer reaction. In the oxidation process of diuron, a stepwise nucleophilic substitution of chlorine by hydroxyl and a stepwise oxidation process of the methyl on the dimethylurea group by hydroxyl and sulfate radical were proposed. PMID:24220194

  16. Influence of high dietary iron as ferrous carbonate and ferrous sulfate on iron metabolism in young calves.

    PubMed

    McGuire, S O; Miller, W J; Gentry, R P; Neathery, M W; Ho, S Y; Blackmon, D M

    1985-10-01

    Twelve intact male Holstein calves averaging 90 kg and 12 wk of age were fed one of three dietary treatments for 28 d. The diets were A) control, B) control plus 1000 ppm iron as ferrous carbonate, and C) control plus 1000 ppm iron as ferrous sulfate monohydrate. Calves were dosed orally on d 15 of the treatment period with 1 mCi of iron-59. Neither source of added iron had a significant effect on weight gains, feed consumption, hemoglobin, packed cell volume, serum total iron, serum total iron-binding capacity, unbound iron-binding capacity, serum copper, tissue copper, fecal dry matter, or a consistent effect on fecal pH. The ferrous carbonate had no significant effect on stable zinc or stable iron in any tissue studied. Calves fed ferrous sulfate had higher average stable iron in most tissues and significantly more in the small intestine. Tissue zinc was lower in spleen and pancreas of ferrous sulfate-fed calves. Both sources of added iron sharply reduced iron-59 in serum, whole blood, and body tissues. The reduction was substantially greater in calves fed the ferrous sulfate iron. Iron in ferrous sulfate had a higher biological availability than that in the ferrous carbonate; however, bioavailability of the ferrous carbonate iron appeared to be substantial and considerably more than that noted in previous studies in which a different source of ferrous carbonate was used. The maximum safe level of dietary iron is materially influenced by the source of iron with a higher tolerance indicated for ferrous carbonated than ferrous sulfate monohydrate. PMID:4067037

  17. Sputter Yield Measurement of Ferrous Metals & Alloys

    NASA Astrophysics Data System (ADS)

    Denieffe, Kieran; Mahony, C. M. O.; Maguire, P. D.; Baby, A.

    2009-10-01

    Sputter yield measurements for bulk Co, Fe & Ni are published [1]; however no values are available for ferrous metal alloys. Here we present the results of a study of the sputter yields of thin film ferromagnetic alloys CoFe & NiFe. We also investigate the sputtering of polyamide, used for masking in microelectronics, but with no published sputter yields to our knowledge. We used a 13.56 MHz plasma ion source to bombard biased samples with 50 eV to 1k eV Ar^+ ions. The ion flux was measured by a Faraday cup & the etch rate with a sensitive quartz crystal microbalance (QCM) modified for rf use, allowing multiple real-time measurements without breaking vacuum. The QCM was calibrated via profilometry & weight loss measurements; flux values were validated using a retarding field analyzer. A mass/energy analyser was used to measure ion energy distributions, showed the FWHM spread of beam energy to be 4eV. Measurements show that although Y values & threshold energies of the thin film alloys differ to those published for bulk ferrous metals, they do exhibit similar Y v ion energy trends.[4pt] [1] Laegreid N, Wehner G. 1961 J Appl Phys 32 p365

  18. 21 CFR 184.1307d - Ferrous fumarate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...of Specific Substances Affirmed as GRAS § 184.1307d Ferrous fumarate. (a) Ferrous fumarate (iron (II) fumarate, (C4 H2 FeO4 ), CAS Reg. No. 141-01-5) is an odorless, reddish-orange to reddish-brown powder. It may...

  19. A case of ferrous sulfate addition enhancing chalcopyrite leaching

    Microsoft Academic Search

    Naoki Hiroyoshi; Masahiko Hirota; Tsuyoshi Hirajima; Masami Tsunekawa

    1997-01-01

    It is generally accepted that ferric ions as an oxidant are effective for leaching chalcopyrite but ferrous ions contribute to the leaching only as a source of ferric ions. However, this paper found that several chalcopyrite samples were more effectively leached in ferrous sulfate solution than in ferric sulfate solution. Chalcopyrite samples from four different sources were leached in 0.1

  20. Influence of High Dietary Iron as Ferrous Carbonate and Ferrous Sulfate on Iron Metabolism in Young Calves[1] and [2

    Microsoft Academic Search

    S. O. Mcguire; W. J. Miller; R. P. Gentry; M. W. Neathery; S. Y. Ho; D. M. Blackmon

    1985-01-01

    Twelve intact male Holstein calves averaging 90 kg and 12 wk of age were fed one of three dietary treatments for 28 d. The diets were A) control, B) control plus 1000 ppm iron as ferrous carbonate, and C) control plus 1000 ppm iron as ferrous sulfate monohydrate. Calves were dosed orally on d 15 of the treatment period with

  1. Inhibition of [3H]MK-801 binding by ferrous (II) but not ferric (III) ions in a manner different from that by sodium nitroprusside (II) in rat brain synaptic membranes.

    PubMed

    Shuto, M; Ogita, K; Minami, T; Maeda, H; Yoneda, Y

    1997-08-01

    The addition of sodium nitroprusside (SNP) significantly inhibited binding of (+)-5- [3H]methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine ([3H]MK-801) to an ion channel associated with the N-methyl-D-aspartate (NMDA) receptor in a concentration-dependent manner at concentrations of >1 microM in rat brain synaptic membranes not extensively washed. However, neither S-nitroso-N-acetylpenicillamine nor S-nitroso-L-glutathione inhibited binding even at 100 microM. Of the two compounds structurally related to SNP (II), similarly potent inhibition was induced by potassium ferrocyanide (II) but not by potassium ferricyanide (III). In addition, ferrous chloride (II) induced much more potent inhibition of binding than ferric chloride (III), at a similar concentration range. In contrast, iron chelators prevented the inhibition by ferrous chloride (II) without markedly affecting that by SNP (II) and potassium ferrocyanide (II). Pretreatment with ferrous chloride (II) also led to potent inhibition of [3H]MK-801 binding in a manner insensitive to subsequent addition of the iron chelators. Pretreatment with Triton X-100 resulted in significant potentiation of the ability of ferrous chloride (II) to inhibit [3H]MK-801 binding irrespective of the addition of agonists, moreover, although binding of other radioligands to the non-NMDA receptors was unaltered after pretreatment first with Triton X-100 and then with ferrous chloride (II). These results suggest that ferrous ions (II) may interfere selectively with opening processes of the NMDA channel through mechanisms entirely different from those underlying the inhibition by both SNP (II) and potassium ferrocyanide (II) in rat brain. PMID:9231735

  2. Effects of Iron Chelators, Iron Salts, and Iron Oxide Nanoparticles on the Proliferation and the Iron Content of Oligodendroglial OLN-93 Cells

    Microsoft Academic Search

    Michaela Hohnholt; Mark Geppert; Ralf Dringen

    2010-01-01

    The oligodendroglial cell line OLN-93 was used as model system to investigate the consequences of iron deprivation or iron\\u000a excess on cell proliferation. Presence of ferric or ferrous iron chelators inhibited the proliferation of OLN-93 cells in\\u000a a time and concentration dependent manner, while the application of a molar excess of ferric ammonium citrate (FAC) prevented\\u000a the inhibition of proliferation

  3. Iron chelators and iron toxicity

    Microsoft Academic Search

    Gary M. Brittenham

    2003-01-01

    Iron chelation may offer new approaches to the treatment and prevention of alcoholic liver disease. With chronic excess, either iron or alcohol alone may individually injure the liver and other organs. In combination, each exaggerates the adverse effects of the other. In alcoholic liver disease, both iron and alcohol contribute to the production of hepatic fibrosis through their effects on

  4. Iron chelation and multiple sclerosis

    PubMed Central

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

    2014-01-01

    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

  5. Metallic Recovery and Ferrous Melting Processes

    SciTech Connect

    Luis Trueba

    2004-05-30

    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.

  6. Crystallography of TWIP Steel Graduate Institute of Ferrous Technology

    E-print Network

    Cambridge, University of

    Crystallography of TWIP Steel By Bo Qin Graduate Institute of Ferrous Technology Pohang University this problem. A physical model based on the mathematical geometry of crystallography of mechanical twinning has

  7. Chelation therapy for iron overload

    Microsoft Academic Search

    James C. Barton

    2007-01-01

    Iron overload is characterized by excessive iron deposition and consequent injury and dysfunction of the heart, liver, anterior\\u000a pituitary, pancreas, and joints. Because physiologic mechanisms to excrete iron are very limited, patients with iron overload\\u000a and its complications need safe, effective therapy that is compatible with their coexisting medical conditions. The availability\\u000a of three licensed iron chelation drugs (one parenteral,

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

    Microsoft Academic Search

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

    2010-01-01

    Iron chelators are effective at removing iron from the body in iron overload, but little is known about the handling of iron\\u000a chelates by the kidney. We studied the transport of deferoxamine, deferasirox, and three hydroxypyridones, and their iron\\u000a chelates, in polarized renal epithelial MDCK cells growing on Transwell inserts. Directional iron efflux was also studied\\u000a in 59Fe-loaded cells. The

  9. Shortened forms of provocative lead chelation

    Microsoft Academic Search

    Rosemary K. Sokas; Joyce Atleson; James P. Keogh

    1988-01-01

    Shortened urinary lead collections following provocative chelation have been standardized for pediatric patients, but have not been considered adequate for adults. This study compared shortened urine collections for lead excretion post chelation with standard 24-hour collections. Thirty-five patients without known current lead exposure and with serum creatinine measurements less than 2 mg\\/dL were hospitalized and had provocative chelation performed as

  10. [Ferrous-manganese oxidizing bacteria from the nature water].

    PubMed

    Qin, Song-yan; Ma, Fang; Huang, Peng

    2008-06-01

    Glass slides were hanged into a canal to acquire the ferrous-manganese oxidizing bacteria settled bio-film. Two isolated methods for ferrous-manganese oxidizing bacteria with special iron-manganese oxidizing matrix from the bio-film were tested. Element component of bacteria product and sheath structure of bacteria were analyzed. With two methods, plate cultivation and the novel semi-solid in situ cultivation method, strains belong to Family Leptothrix were isolated. XRF showed that the amorphous iron and manganese were two major metal elements of the precipitation formed by one strain of Leptothrix spp.. Through the microscope observation, one strain of Family Leptothrix was determined to form branch-like structured sheath, while another strain formed spider web-like structured sheath. Those isolated bacteria provide model strains for future testing of FISH probe and PCR primer of ferrous-manganese oxidizing bacteria. PMID:18763517

  11. Use of ferrous fumarate to fortify foods for infants and young children.

    PubMed

    Hurrell, Richard

    2010-09-01

    Ferrous fumarate is currently recommended for use in the fortification of foods for infants and young children. This recommendation is based on the compound's good sensory properties and on results from isotope studies in adults that reported similar iron absorption values for ferrous fumarate and ferrous sulphate (relative bioavailability [RBV] of ferrous fumarate, 100). However, later isotope studies conducted on both iron-replete and iron-deficient young children found that iron absorption from ferrous fumarate was only about 30% of that achieved from ferrous sulphate (RBV, 30). The reasons for the differences observed in adults compared with children are unclear but could be related to the following factors: lower iron status in children resulting in greater iron absorption via upregulation from ferrous sulphate but not from ferrous fumarate; reduced gastric acid secretion in children leading to retarded dissolution of ferrous fumarate; or an influence of added ascorbic acid on RBV. Ferrous fumarate-fortified complementary foods have been demonstrated to improve iron status in iron-deficient infants and, more recently, to prevent iron deficiency equally as well as ferrous sulphate in iron-replete infants. However, current evidence indicates that iron-deficient infants and young children may absorb iron from ferrous fumarate less well than iron from ferrous sulfate and that, for equivalent efficacy, complementary foods targeted at such infants and young children should contain more iron in the form of fumarate. PMID:20796217

  12. Ascorbate status modulates reticuloendothelial iron stores and response to deferasirox iron chelation in ascorbate-deficient rats.

    PubMed

    Brewer, Casey; Otto-Duessel, Maya; Lykkesfeldt, Jens; Nick, Hanspeter; Wood, John C

    2012-10-01

    Iron chelation is essential to patients on chronic blood transfusions to prevent toxicity from iron overload and remove excess iron. Deferasirox (DFX) is the most commonly used iron chelator in the United States; however, some patients are relatively refractory to DFX therapy. We postulated that vitamin C supplementation would improve the availability of transfusional iron to DFX treatment by promoting iron's redox cycling, increasing its soluble ferrous form and promoting its release from reticuloendothelial cells. Osteogenic dystrophy rats (n = 54) were given iron dextran injections for 10 weeks. Cardiac and liver iron levels were measured after iron loading (n = 18), 12 weeks of sham chelation (n = 18), and 12 weeks of DFX chelation (n = 18) at 75 mg/kg/day. Ascorbate supplementation of 150 ppm, 900 ppm, and 2250 ppm was used in the chow to mimic a broad range of ascorbate status; plasma ascorbate levels were 5.4 ± 1.9, 8.2 ± 1.4, 23.6 ± 9.8 ?M, respectively (p < 0.0001). The most severe ascorbate deficiency produced reticuloenthelial retention, lowering total hepatic iron by 29% at the end of iron loading (p < 0.05) and limiting iron redistribution from cardiac and hepatic macrophages during 12 weeks of sham chelation. Most importantly, ascorbate supplementation at 2250 ppm improved DFX efficiency, allowing DFX to remove 21% more hepatic iron than ascorbate supplementation with 900 ppm or 150 ppm (p < 0.05). We conclude that vitamin C status modulates the release of iron from the reticuloendothelial system and correlates positively with DFX chelation efficiency. Our findings suggest that ascorbate status should be probed in patients with unsatisfactory response to DFX. PMID:22713799

  13. 40 CFR 464.30 - Applicability; description of the ferrous casting subcategory.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Applicability; description of the ferrous casting subcategory. 464.30 Section 464.30...STANDARDS (CONTINUED) METAL MOLDING AND CASTING POINT SOURCE CATEGORY Ferrous Casting Subcategory § 464.30 Applicability;...

  14. 40 CFR 464.30 - Applicability; description of the ferrous casting subcategory.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Applicability; description of the ferrous casting subcategory. 464.30 Section 464.30...GUIDELINES AND STANDARDS METAL MOLDING AND CASTING POINT SOURCE CATEGORY Ferrous Casting Subcategory § 464.30 Applicability;...

  15. 40 CFR 464.30 - Applicability; description of the ferrous casting subcategory.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Applicability; description of the ferrous casting subcategory. 464.30 Section 464.30...STANDARDS (CONTINUED) METAL MOLDING AND CASTING POINT SOURCE CATEGORY Ferrous Casting Subcategory § 464.30 Applicability;...

  16. 40 CFR 464.30 - Applicability; description of the ferrous casting subcategory.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Applicability; description of the ferrous casting subcategory. 464.30 Section 464.30...STANDARDS (CONTINUED) METAL MOLDING AND CASTING POINT SOURCE CATEGORY Ferrous Casting Subcategory § 464.30 Applicability;...

  17. Orange but not apple juice enhances ferrous fumarate absorption in small children

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ferrous fumarate is a common, inexpensive iron form increasingly used instead of ferrous sulfate as a food iron supplement. However, few data exist as to whether juices enhance iron absorption from ferrous fumarate. We studied 21 children, ages 4.0 to 7.9 years using a randomized crossover design. S...

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

    E-print Network

    Bogyo, Matthew

    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

  19. Enhancement of chalcopyrite leaching by ferrous ions in acidic ferric sulfate solutions

    Microsoft Academic Search

    Naoki Hiroyoshi; Hajime Miki; Tsuyoshi Hirajima; Masami Tsunekawa

    2001-01-01

    The effects of ferrous ions on chalcopyrite oxidation with ferric ions in 0.1 mol dm?3 sulfuric acid solutions were investigated by leaching experiments at 303 K in nitrogen. With high cupric ion concentrations, the chalcopyrite oxidation was enhanced by high concentrations of ferrous ions and copper extraction was mainly controlled by the concentration ratio of ferrous to ferric ions or

  20. Pyrogallol red-molybdate: a reversible, metal chelate stain for detection of proteins immobilized on membrane supports.

    PubMed

    Shojaee, N; Patton, W F; Lim, M J; Shepro, D

    1996-04-01

    Certain metal complexes selectively interact with proteins immobilized on solid-phase membrane supports to form brightly colored products. The metal chelates form protein-dye complexes in the presence of metal ions at acidic pH but are eluted from the proteins by immersing membranes in a solution of basic pH that contains other chelating agents. The reversible nature of the protein staining procedure allows for subsequent biochemical analyses, such as immunoblotting, N-terminal and internal protein sequencing. Among the metal complexes evaluated to date, the triazine dye-ferrous complexes (ferene S, ferrozine) and the ferrocyanide-ferric complexes provide the most sensitive detection of proteins immobilized on membranes. While the pyrogallol red-molybdate complex is commonly used in solution-based total protein assays, its utility as a reversible stain for proteins immobilized on membranes has not been reported. Pyrogallol red-molybdate complexes readily stain proteins on nitrocellulose and polyvinyl difluoride membranes with similar sensitivity as ferrozine-ferrous complexes. Analysis of charge-fractionated carrier ampholytes and synthetic polymers of different L-amino acids indicate that binding is prominently via protonated alpha and epsilon-amino side chains. Carbamylation of amino groups in bovine serum albumin substantially diminishes pyrogallol red-molybdate binding to the protein. The stain is reversible, resistant to chemical interference, and compatible with immunoblotting. PMID:8738328

  1. Chelators affecting iron absorption in mice.

    PubMed

    Kontoghiorghes, G J

    1990-12-01

    The effect of natural and synthetic chelators on iron (59Fe) absorption in mice has been studied in three different experiments using single or repeated intragastric administrations of chelator iron (59Fe) complexes of different chelator doses. The amount of 59Fe in whole animals, their excretions and also distribution of 59Fe in blood, liver, spleen and heart was measured at one, three and eight weeks following the 59Fe-chelator administrations and compared to controls which received the same amount of iron (59Fe) but no chelator. 2-Hydroxy-4-methoxypyridine-1-oxide and maltol, which form lipophilic iron complexes, were found to cause an increase of 59Fe absorption while other chelators caused a decrease either by precipitating iron eg. 2-hydroxypyridine-1-oxide or by forming non absorbable soluble iron complexes eg. desferrioxamine, mimosine, EDTA. 1,2-Dimethyl-3-hydroxypyrid-4-one caused a decrease in iron absorption at a high dose (10 mg) by comparison to the control group but it did not significantly alter iron absorption at a lower dose (2 mg). It is suggested that natural and synthetic iron chelating compounds influence the absorption of iron and some may have a use in the treatment of diseases associated with gastro-intestinal iron absorption imbalance. PMID:2095129

  2. Enhanced NO{sub x} removal in wet scrubbers using metal chelates. Final report, Volume 2

    SciTech Connect

    NONE

    1992-12-01

    Successful pilot plant tests of simultaneous removal of SO{sub 2} and NO{sub x} in a wet lime flue gas desulfurization system were concluded in December. The test, 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 plant 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 SO{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 MW. Ferrous EDTA reacts with nitric oxide, NO, which comprises about 96% of NO{sub x} from coal-fired boilers. In this report, although not precise, NO and NO{sub x} are used interchangeably. 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. Volume 2 covers: description and results of NO{sub x} removal tests; and description and results of waste characterization studies.

  3. Development of iron chelators for Cooley's anemia. Final report

    Microsoft Academic Search

    W. H. Crosby; R. Green

    1982-01-01

    Iron chelators were screened in an iron-loaded rat model using selective radioiron probes. In all experiments, chelators D and F, in that order, induced significant loss of radioiron compared with controls. However, use of chelator D was associated with side effects, and resulted in the death of some animals. There was some evidence that chelator A also caused iron loss

  4. Partition coefficients of cobalt chelates and chelating agents between aqueous solutions and supercritical carbon dioxide

    Microsoft Academic Search

    F Gervais; C Perre; S Sarrade; L Barna; P Moszkowicz; S Barguès

    2003-01-01

    Distribution (or partition) coefficients (Dx) of several chelating agents and cobalt-chelates between aqueous phases and SC CO2 were determined. ?-Diketones and dithiocarbamates fluorinated or not were the investigated chelating agents for cobalt. Different solute concentrations and different aqueous phase pH values were experienced for fixed operating conditions at 270 bar pressure and 50°C temperature. The results obtained were compared with

  5. Fluid extraction using carbon dioxide and organophosphorus chelating agents

    DOEpatents

    Smart, Neil G. (Moscow, ID); Wai, Chien M. (Moscow, ID); Lin, Yuehe (Moscow, ID); Kwang, Yak Hwa (Moscow, ID)

    1998-01-01

    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.

  6. Questions and Answers on Unapproved Chelation Products

    MedlinePLUS

    ... 4. Why did FDA take this action? Companies marketing unapproved OTC chelation products with unsubstantiated treatment claims violate the Federal Food, Drug, and Cosmetic Act. Although some of these ...

  7. Heme Coordination States of Unfolded Ferrous Cytochrome c

    Microsoft Academic Search

    Enrica Droghetti; Silke Oellerich; Peter Hildebrandt; Giulietta Smulevich

    2006-01-01

    The structural changes of ferrous Cyt-c that are induced by binding to SDS micelles, phospholipid vesicles, DeTAB, and GuHCl as well as by high temperatures and changes in the pH have been studied by RR and UV-Vis absorption spectroscopies. Four species have been identified in which the native methionine-80 ligand is removed from the heme iron. This coordination site is

  8. Chromate removal from aqueous wastes by reduction with ferrous ion

    Microsoft Academic Search

    L. E. Eary; Dhanpat Rai

    1988-01-01

    Experimental measurements of reaction stoichiometries indicate that optimum conditions for chromate removal from oxygenated, 25°C aqueous wastes by reduction with ferrous ion occur at pH less than 10.0 in solutions containing the following anions: ClOâ⁻, Cl⁻, F⁻, NOâ⁻, and POâ\\/sup 3 -\\/. At pH greater than 10.0 and at lower pH in solutions that contain greater than 10⁻⁴ M total

  9. Removing Chlorite by the Addition of Ferrous Iron

    Microsoft Academic Search

    Angela Iatrou; William R. Knocke

    1992-01-01

    The application of chlorine dioxide in water treatment has been limited because of concerns about the health effects of residual chlorite (CKV) and chlorate. This study investigated the feasibility of using ferrous iron (Fe[II]) to reduce chlorite concentrations. Laboratory tests indicated a required reaction stoichiometry of 3.0-3.1 mg Fe(II)\\/mg ClO??. The reaction rate was rapid for pH values of 5

  10. Ferrous sulfate liposomes: preparation, stability and application in fluid milk

    Microsoft Academic Search

    Shuqin Xia; Shiying Xu

    2005-01-01

    The effects of cholesterol and Tween 80 on the physical stability of empty liposomes were investigated. Results showed that the physical stability of liposomes, including electrostatic and steric stability, was improved by addition of cholesterol and Tween 80. Liposomes prepared by different methods, thin-film hydration, thin-film sonication, reverse-phase evaporation and freeze-thawing, were tested for their capacity to encapsulate ferrous sulfate.

  11. A model for ferrous-promoted chalcopyrite leaching

    Microsoft Academic Search

    Naoki Hiroyoshi; Hajime Miki; Tsuyoshi Hirajima; Masami Tsunekawa

    2000-01-01

    Oxidative leaching of chalcopyrite with dissolved oxygen and\\/or with ferric ions is promoted by high concentrations of ferrous ions in sulfuric acid solutions containing cupric ions. This paper proposes a reaction model to interpret this phenomenon and the thermodynamics of the leaching is discussed.The model considers the leaching to take place in two steps: (1) reduction of chalcopyrite to Cu2S

  12. Iron Reverses Impermeable Chelator Inhibition of DNA Synthesis in CCl39 Cells

    NASA Astrophysics Data System (ADS)

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

    1994-08-01

    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.

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

    PubMed Central

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

    2014-01-01

    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

  14. Iron (FeII) chelation, ferric reducing antioxidant power, and immune modulating potential of Arisaema jacquemontii (Himalayan Cobra Lily).

    PubMed

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

    2014-01-01

    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 ? MFe(3+)/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

  15. Topical applications of iron chelators in photosensitization.

    PubMed

    Juzeniene, Asta; Juzenas, Petras; Iani, Vladimir; Moan, Johan

    2007-12-01

    Generation of the reactive oxygen species (ROS) in skin by exposure to ultraviolet (UV) radiation induces a number of cutaneous pathologies such as skin cancer, photosensitization, and photoaging among others. Skin iron catalyzes UV generation of ROS. Topical application of iron chelators reduces erythema, epidermal and dermal hypertrophy, wrinkle formation, tumour appearance. It has been proposed that iron chelators can be useful agents against damaging effects of both short- and long-term UV exposure. A better understanding of the action mechanisms of iron chelators, might be useful to developing effective anticancer and antiphotoaging cosmetic products. Iron chelators may lead to accumulation of protoporphyrin IX (PpIX), a strong photosensitizer. The action of iron chelators in skin, related to PpIX increase has not yet been thoroughly studied. Therefore, we have investigated the formation of PpIX in normal mouse skin after topical application of creams containing metal chelators. The amount and distribution of porphyrins formed was determined by means of non-invasive fluorescence spectroscopy. Deferoxamine (DF), ethylenediaminetetraacetic acid (EDTA), 1,2-diethyl-3-hydroxypyridin-4-one (CP94), but not meso-2,3-dimercaptosuccinic acid (DMSA), caused increased accumulation of endogenous porphyrins in the skin. Fluorescence excitation and emission spectroscopy confirmed that PpIX was the main fluorescent species. The amount of PpIX accumulated in skin under the present conditions was not large enough to produce any significant erythema after light exposure. Further studies are needed to evaluate the role of PpIX induced by iron chelators used, against photoaging and cancer prevention. PMID:18046481

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

    SciTech Connect

    Hiroyoshi, Naoki; Hirota, Masahiko; Hirajima, Tsuyoshi; Tsunekawa, Masami

    1999-08-20

    A substantial amount of copper is obtained by dump leaching of low-grade ore that would otherwise become waste. 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/dm{sup 3} 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.

  17. Method and apparatus for back-extracting metal chelates

    DOEpatents

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

    1998-08-11

    A method is described for extracting metal and metalloid species from a solid or liquid substrate using a supercritical fluid solvent containing one or more chelating agents followed by back-extracting the metal and metalloid species from the metal and metalloid chelates formed thereby. The back-extraction acidic solution is performed utilizing an acidic solution. Upon sufficient exposure of the metal and metalloid chelates to the acidic solution, the metal and metalloid species are released from the chelates into the acid solution, while the chelating agent remains in the supercritical fluid solvent. The chelating agent is thereby regenerated and the metal and metalloid species recovered. 3 figs.

  18. Iron mobilization using chelation and phlebotomy.

    PubMed

    Flaten, Trond Peder; Aaseth, Jan; Andersen, Ole; Kontoghiorghes, George J

    2012-06-01

    Knowledge of the basic mechanisms involved in iron metabolism has increased greatly in recent years, improving our ability to deal with the huge global public health problems of iron deficiency and overload. Several million people worldwide suffer iron overload with serious clinical implications. Iron overload has many different causes, both genetic and environmental. The two most common iron overload disorders are hereditary haemochromatosis and transfusional siderosis, which occurs in thalassaemias and other refractory anaemias. The two most important treatment options for iron overload are phlebotomy and chelation. Phlebotomy is the initial treatment of choice in haemochromatosis, while chelation is a mainstay in the treatment of transfusional siderosis. The classical iron chelator is deferoxamine (Desferal), but due to poor gastrointestinal absorption it has to be administered intravenously or subcutaneously, mostly on a daily basis. Thus, there is an obvious need to find and develop new effective iron chelators for oral use. In later years, particularly two such oral iron chelators have shown promise and have been approved for clinical use, namely deferiprone (Ferriprox) and deferasirox (Exjade). Combined subcutaneous (deferoxamine) and oral (deferiprone) treatment seems to hold particular promise. PMID:22565013

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

    PubMed

    Jones, Terry A; Parmar, Satyesh C

    2006-12-01

    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

  20. Combined SO{sub 2}/NO{sub x} control using ferrous{center_dot}EDTA and a secondary additive in a lime-based aqueous scrubber system

    SciTech Connect

    Mendelsohn, M.H.; Livengood, C.D.; Harkness, J.B.L.

    1991-12-01

    Integration of NO{sub x} control into existing flue-gas desulfurization (FGD) systems addresses site-specific control requirements while minimizing retrofit difficulties. Argonne has studied the use of the metal-chelate additives, such as ferrous{center_dot}EDTA in various wet FGD chemistries, to promote combined SO{sub 2}/NO{sub x} scrubbing. A major process problem is oxidation of the iron to the ferric species, leading to a significant decrease in NO{sub x}-removal capability. Argonne discovered a class of organic compounds that, when used with ferrous{center_dot}EDTA in a sodium carbonate chemistry, could maintain high levels of NO{sub x} removal. However, those antioxidant/reducing agents are not effective in a lime-based chemistry, and a broader investigation of antioxidants was initiated. This paper discusses results of that investigation, which found a practical antioxidant/reducing agent capable of maintaining NO{sub x} removals of about 50% (compared with about 15% without the agent) in a lime-based FGD chemistry with FE(II){center_dot}EDTA. 5 refs., 10 figs.

  1. Mercury emission and behavior in primary ferrous metal production

    NASA Astrophysics Data System (ADS)

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

    2011-07-01

    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.

  2. Objectives and Methods of Iron Chelation Therapy

    PubMed Central

    Hershko, C.; Abrahamov, A.; Konijn, A. M.; Breuer, W.; Cabantchik, I. Z.; Pootrakul, P.; Link, G.

    2003-01-01

    Recent developments in the understanding of the molecular control of iron homeostasis provided novel insights into the mechanisms responsible for normal iron balance. However in chronic anemias associated with iron overload, such mechanisms are no longer sufficient to offer protection from iron toxicity, and iron chelating therapy is the only method available for preventing early death caused mainly by myocardial and hepatic damage. Today, long-term deferoxamine (DFO) therapy is an integral part of the management of thalassemia and other transfusion-dependent anemias, with a major impact on well-being and survival. However, the high cost and rigorous requirements of DFO therapy, and the significant toxicity of deferiprone underline the need for the continued development of new and improved orally effective iron chelators. Within recent years more than one thousand candidate compounds have been screened in animal models. The most outstanding of these compounds include deferiprone (L1); pyridoxal isonicotinoyl hydrazone (PIH) and; bishydroxy- phenyl thiazole. Deferiprone has been used extensively as a substitute for DFO in clinical trials involving hundreds of patients. However, L1 treatment alone fails to achieve a negative iron balance in a substantial proportion of subjects. Deferiprone is less effective than DFO and its potential hepatotoxicity is an issue of current controversy. A new orally effective iron chelator should not necessarily be regarded as one displacing the presently accepted and highly effective parenteral drug DFO. Rather, it could be employed to extend the scope of iron chelating strategies in a manner analogous with the combined use of medications in the management of other conditions such as hypertension or diabetes. Coadministration or alternating use of DFO and a suitable oral chelator may allow a decrease in dosage of both drugs and improve compliance by decreasing the demand on tedious parenteral drug administration. Combined use of DFO and L1 has already been shown to result in successful depletion of iron stores in patients previously failing to respond to single drug therapy, and to lead to improved compliance with treatment. It may also result in a “shuttle effect” between weak intracellular chelators and powerful extracellular chelators or exploit the entero-hepatic cycle to promote fecal iron excretion. All of these innovative ways of chelator usage are now awaiting evaluation in experimental models and in the clinical setting. PMID:18365050

  3. Microwave Absorption Characteristics of Conventionally Heated Nonstoichiometric Ferrous Oxide

    Microsoft Academic Search

    Zhiwei Peng; Jiann-Yang Hwang; Joe Mouris; Ron Hutcheon; Xiang Sun

    2011-01-01

    The temperature dependence of the microwave absorption of conventionally heated nonstoichiometric ferrous oxide (Fe0.925O) was characterized via the cavity perturbation technique between 294 K and 1373 K (21 °C and 1100 °C). The complex relative permittivity and permeability\\u000a of the heated Fe0.925O sample slightly change with temperature from 294 K to 473 K (21 °C to 200 °C). The dramatic variations of permittivity and\\u000a permeability of the sample

  4. Self-diffusion of iron and sulfur in ferrous sulfide

    Microsoft Academic Search

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

    1974-01-01

    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

  5. Overview of Lightweight Ferrous Materials: Strategies and Promises

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

    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.

  6. Overview of Lightweight Ferrous Materials: Strategies and Promises

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

    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.

  7. Chelates of cerium (IV), their preparation and gasoline containing said chelates

    Microsoft Academic Search

    Hartle

    1977-01-01

    A gasoline motor fuel having improved antiknock characteristics is obtained by incorporating a novel chelate of cerium (IV) in the gasoline. Examples of the novel chelates of cerium (IV) inclued ps ceric 2,4-hexanedionate; ceric 3,5-octanedionate; ceric 2,2-dimethyl-3,5-heptanedionate; ceric 2,6-dimethyl-3,5-heptanedionate; and ceric 2,2,6,6-tetramethyl-3,5-heptanedionate. The chelates of cerium(IV) are prepared by a novel oxidative ligand exchange reaction between cerous acetylacetonate and a

  8. Lanthanide Chelates as a Tool in Nucleic Acid Chemistry

    PubMed Central

    Mukkala, Veli-Matti; Takalo, Harri; Liitti, Päivi; Kankare, Jouko; Kuusela, Satu

    1994-01-01

    The potentiality of lanthanide chelates as photoluminescent markers and cleaving agents of nucleic acids is discussed, the main emphasis being on the chelates derived from aromatic nitrogen bases. PMID:18476232

  9. Deferiprone iron chelation as a novel therapy for experimental mucormycosis

    Microsoft Academic Search

    Ashraf S. Ibrahim; John E. Edwards Jr; Yue Fu; Brad Spellberg

    2006-01-01

    Objectives: Patients treated with the iron chelator deferoxamine are known to be more susceptible to mucormycosis. However, while deferoxamine is an iron chelator from the perspective of the human host, deferoxamine actually serves as a siderophore, delivering free iron to Rhizopus oryzae, the major cause of mucormycosis. Other iron chelators, including deferiprone, which do not deliver iron to R. oryzae

  10. Iron mobilization from ferritin using alpha-oxohydroxy heteroaromatic chelators.

    PubMed Central

    Kontoghiorghes, G J

    1986-01-01

    Several alpha-oxohydroxy heteroaromatic chelators have been shown to mobilize iron from horse spleen ferritin. Although the reactions were slow, taking up to 3 days to reach completion, the amounts of iron mobilized were higher than those reported for other chelators. These results increase the prospects for the clinical use of alpha-oxohydroxy chelators in the treatment of iron overload. PMID:3954731

  11. The chelation of nonheme iron within sickle erythrocytes by the hydroxypyridinone chelator CP094.

    PubMed

    Hartley, A; Rice-Evans, C

    1992-09-01

    Nonheme, nonferritin iron has been detected in membrane preparations from sickle erythrocytes and has been suggested to catalyze free radical reactions in these cells contributing to the development of membrane oxidation. In this study the hydroxypyridinone iron chelator, CP094, currently being evaluated as a potentially therapeutic chelator, and desferrioxamine have been studied for their abilities to chelate the nonheme iron within intact sickle erythrocytes under physiological conditions. The results suggest that CP094 can enter sickle erythrocytes, chelate nonheme iron and suppress membrane lipid peroxidation within a timescale in which desferrioxamine does not enter the cells. Suppression of lipid peroxidation showed no protective effect in an in vitro system inducing the formation of irreversibly sickled cells. PMID:1497355

  12. New chelation therapies and emerging chelating drugs for the treatment of iron overload.

    PubMed

    Kontoghiorghes, George J

    2006-03-01

    Iron chelation therapy using deferoxamine or deferiprone (L1) is effective for the treatment of most transfused iron-loaded patients. The combination administration of deferiprone in the daytime and deferoxamine in the night appears to be universally effective in rapidly achieving negative iron balance. The cardiac iron removal effect of deferiprone increases the prospects of longer survival in beta-thalassaemia patients. New chelators have reached the stage of clinical development such as deferitrin, 1-allyl-2-methyl-3-hydroxypyrid-4-one (L1NAll) and the starch deferoxamine polymers. Deferasirox has received a conditional approval in the US under the FDA-accelerated approval regulations, but needs further verification of its efficacy and safety. Future iron chelation therapies are likely to be based on combinations of chelating drugs. PMID:16503822

  13. Analyzing the international exergy flow network of ferrous metal ores.

    PubMed

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

    2014-01-01

    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

  14. Chelated Indium Activable Tracers for Geothermal Reservoirs

    E-print Network

    Stanford University

    SGP-TR-99 Chelated Indium Activable Tracers for Geothermal Reservoirs Constantinos V. Indium was se1ecti:d to be the most promising activable tracer. The thermal stability of indium tracer of the soluble indium concentration was made as a f'unction of time by neutron activation analysis. From the data

  15. Metal chelate catalysts for fuel cells

    NASA Astrophysics Data System (ADS)

    Darby, R.; Yamana, M.; Dhar, H.; White, R.

    1982-10-01

    Various modified forms of several organometallic chelate compounds were synthesized and tested for their activity and stability as oxygen reduction electrocatalysts in sulfuric acid electrolyte. The most active catalysts found were cobalt tetraazaannulene (CoTAA), iron phthalocyanine (FePc) and cobalt tetraphenylporphyrin (CoTPP). However, these catalysts have limited stability in strong acids.

  16. Metal chelate catalysts for fuel cells

    Microsoft Academic Search

    R. Darby; M. Yamana; H. Dhar; R. White

    1982-01-01

    Various modified forms of several organometallic chelate compounds were synthesized and tested for their activity and stability as oxygen reduction electrocatalysts in sulfuric acid electrolyte. The most active catalysts found were cobalt tetraazaannulene (CoTAA), iron phthalocyanine (FePc) and cobalt tetraphenylporphyrin (CoTPP). However, these catalysts have limited stability in strong acids.

  17. Deferiprone Chelation Therapy for Thalassemia Major

    Microsoft Academic Search

    R. Galanello; S. Campus

    2009-01-01

    Iron overload is one of the major causes of morbidity in patients with thalassemia major. Deferiprone (DFP), an orally active iron chelator, emerged from an extensive search for new drugs to treat iron overload. Comparative studies have shown that at comparable doses the efficacy of DFP in removing body iron is similar to that of desferoxamine (DFO). In retrospective and

  18. Deferitazole, a new orally active iron chelator.

    PubMed

    Hider, Robert C; Kong, Xiaole; Abbate, Vincenzo; Harland, Rachel; Conlon, Kelly; Luker, Tim

    2015-03-21

    Following a systematic search of desferrithiocin analogs, a polyether derivative, deferitazole (formerly FBS0701), has entered into phase 1 and 2 clinical trials with promising biological properties. However, until now, detailed physicochemical properties of this chelator have not been reported. The compound displays a high affinity and selectivity for iron(III) as demonstrated by the log??2 = 33.39 ± 0.03 and the pFe(3+) value of 22.3. Two equilibrating isomeric forms of the iron(III) complex exist under biological conditions. Deferitazole also binds the trivalent metals Al(III) and La(III) with high affinity; log??2 values, 26.68 and 21.55 respectively. The affinity of deferitazole for divalent cations is somewhat lower, with the exception of Cu(II) which possesses a log??2 value of 25.5; deferitazole scavenges iron from labile sources such as citrate and albumin with efficiencies comparable with those of other therapeutic iron chelators, including deferasirox, deferiprone and desferrioxamine. The Fe(III)(deferitazole)2 is stable under physiological conditions and does not redox cycle. The high affinity of deferitazole for iron(III) renders it unlikely that this chelator will lead to the redistribution of iron and consequently deferitazole shows considerable promise as a therapeutic iron(III) chelator. PMID:25687725

  19. Thermal Stability of Chelated Indium Activable Tracers

    SciTech Connect

    Chrysikopoulos, Costas; Kruger, Paul

    1986-01-21

    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.

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

    SciTech Connect

    Piwonka, T.S. [ed.

    1996-01-01

    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.

  1. EFFECT OF HEAT TRANSFER ON CORROSION OF FERROUS ALLOYS IN BOILER WATERS

    Microsoft Academic Search

    W. E. Berry; F. W. Fink

    1963-01-01

    A survey was made of the effect of heat transfer on the corrosion ; behavior of ferrous alloys in boiler waters, particularly as applied to liquid-; metal-heated steam generators. The results showed that ferrous alloy boiler ; tubes may fail during operation from general corrosion, Oâ pitting, on-load ; pitting, caustic embrittlement, chloride stress-corrosion cracking, or corrosion ; fatigue. All

  2. A Mössbauer and X-ray powder diffraction study of some ferrous hematinics.

    PubMed

    Coe, E M; Bowen, L H; Bereman, R D

    1995-06-01

    Iron deficiency anemia is a relatively common illness that can arise from a number of different causes. Three ferrous salts are usually used in its treatment: ferrous fumarate, gluconate, and sulfate. They are administered orally and are relatively well tolerated. These hematinics have been studied by Mössbauer spectroscopy and X-ray powder diffraction, and can easily be distinguished by both techniques. It was found that the two ferrous sulfates studied (Eckerd and SmithKline Beckman Co.) most closely resemble the monohydrate by comparison of the X-ray powder pattern with those of the JCPDS. Both the ferrous fumarate (Femiron) and gluconate (Spring Valley) had approximately 10% ferric iron present. To the authors' knowledge, this is the first reported Mössbauer spectrum for ferrous fumarate. PMID:7500090

  3. Chelation therapy in workers with lead exposure.

    PubMed Central

    Royce, S; Rosenberg, J

    1993-01-01

    Occupational lead overexposure remains a major problem. To evaluate the settings in which physicians appropriately prescribe chelation therapy for lead exposure, 7 cases were identified from physician phone calls and mandatory laboratory reporting of elevated blood lead levels to the California Department of Health Services. In the 2 workers with the highest blood lead levels (both of whom had severe symptoms), treatment was indicated. Physicians inappropriately prescribed chelating agents to workers with ongoing lead exposure as prophylaxis against rising blood lead levels and to treat atherosclerotic heart disease. Workers' personal physicians identified lead overexposure in 5 of the 7 cases. Workplace lead medical surveillance programs mandated by the federal Occupational Safety and Health Administration were inadequate in all 5 of the workplaces where information was available. PMID:8317123

  4. Anacardic acids and ferric ion chelation.

    PubMed

    Tsujimoto, Kazuo; Hayashi, Akio; Ha, Tae Joung; Kubo, Isao

    2007-01-01

    6-Pentadeca(e)nylsalicylic acids isolated from the cashew Anacardium occidentale L. (Anacardiaceae), commonly known as anacardic acids, inhibited the linoleic acid peroxidation catalyzed by soybean lipoxygenase-1 (EC 1.13.11.12, type 1) competitively without prooxidant effects. Their parent compound, salicylic acid, did not have this inhibitory activity up to 800 pm, indicating that the pentadeca(e)nyl group is an essential element to elicit the activity. The inhibition is attributed to its ability to chelate iron in the enzyme. Thus, anacardic acids chelate iron in the active site of the enzyme and then the hydrophobic tail portion slowly begins to interact with the hydrophobic domain close to the active site. Formation of the anacardic acids-ferric ion complex was detected in the ratio of 2:1 as the base peak in the negative ion electrospray ionization mass spectrometry. Hence, anacardic acids inhibit both Eox and Ered forms. PMID:18069245

  5. Federal regulation of unapproved chelation products.

    PubMed

    Lee, Charles E

    2013-12-01

    Chelation products can be helpful in the treatment of metal poisoning. However, many unapproved products with unproven effectiveness and safety are marketed to consumers, frequently via the internet. This paper describes the primary responsibility of the Health Fraud and Consumer Outreach Branch of the United States Food and Drug Administration to identify and address health fraud products. Efforts to prevent direct and indirect hazards to the population's health through regulatory actions are described. PMID:24197664

  6. Enzymes and chelating agent in cotton pretreatment

    Microsoft Academic Search

    Em??lia Csiszár; Anita Losonczi; George Szakács; István Rusznák; László Bezúr; Johanna Reicher

    2001-01-01

    Desized cotton fabric and cotton seed-coat fragments (impurities) have been treated with commercial cellulase (Celluclast 1.5 L), hemicellulase–pectinase (Viscozyme 120 L) and xylanase (Pulpzyme HC) enzymes. Seed-coat fragments hydrolyzed much faster than the cotton fabric itself. This relative difference in hydrolysis rates makes possible a direct enzymatic removal of seed-coat fragments from desized cotton fabric. Addition of chelating agents such

  7. Blood disorders: future trends in iron chelation.

    PubMed

    Jordan, D; Kontoghiorghes, G

    The treatment of iron overload in thalassaemic patients has for some time involved long periods of subcutaneous drug therapy. The inconvenience of sporting a portable syringe driver for up to ten hours at a time has led to reduced patient compliance rates, particularly among adolescent and teenage groups. Dorothy Jordan and George Kontoghiorghes describe a recent breakthrough which could result in many patients being able to resort to oral iron chelation therapy. PMID:2124864

  8. Controversies surrounding iron chelation therapy for MDS.

    PubMed

    Leitch, Heather A

    2011-01-01

    The myelodysplastic syndromes (MDS) are characterized by cytopenias and acute myeloid leukemia risk. Most MDS patients eventually require transfusion of red blood cells for anemia, placing them at risk of iron overload (IOL). In beta-thalassemia major, transfusional IOL leads to organ dysfunction and death, however, with iron chelation therapy survival improved to near normal and organ function was improved. In lower risk MDS, several non-randomized studies suggest an adverse effect of IOL on survival, and that lowering iron minimizes this impact and may improve organ function. While guidelines for MDS generally recommend chelation in selected lower risk patients, data are emerging suggesting IOL may impact adversely on the outcome of higher risk MDS and stem cell transplantation (SCT) and that lowering iron may be beneficial in these patients. Trials to determine whether these effects are truly from lowering iron are currently enrolling. Chelation is costly and potentially toxic, and in MDS should be initiated after weighing potential risks and benefits for each patient until more definitive data are available. In this paper, data on the impact of IOL in MDS and SCT, possible mechanisms of iron toxicity such as oxidative stress, and the impact of lowering iron on organ function and survival are reviewed. PMID:21030120

  9. Effects of iron polymaltose complex, ferrous fumarate and ferrous sulfate treatments in anemic pregnant rats, their fetuses and placentas.

    PubMed

    Toblli, Jorge E; Cao, Gabriel; Oliveri, Leda; Angerosa, Margarita

    2013-06-01

    Although oral iron preparations are widely prescribed to prevent and to treat iron deficiency anemia in pregnancy, comparative data on their effects to the mother, fetus and placenta are limited. In this study, the effects of oral iron polymaltose complex (IPC), ferrous fumarate (FF) and ferrous sulfate (FS) were compared in anemic pregnant rats, their fetuses and placentas. Hematological variables and oxidative stress markers in the liver, heart and kidneys of the dams and fetuses as well as the markers for oxidative stress, inflammation and hypoxia in placentas were assessed. Pregnancy outcome was measured by number of fetuses, and by neonate and placental weight. All therapies were comparably effective in correcting anemia. FS and FF, but not IPC, resulted in liver damage in dams and oxidative stress in dams, fetuses and placentas. FS group presented the highest catalase and GPx levels in dams, fetuses and placentas. IPC, but not FF or FS, restored normal TNF-? and IL6 expression levels in placentas whereas FS-treated animals presented the highest cytokine levels, suggesting a local inflammatory reaction. Anemia-induced high levels of HIF-1? were partially lowered by IPC and FF but further elevated by FS. Most of the negative effects associated with IDA were resolved by IPC treatment. Especially FS treatment was found to elicit hepatic damage in the dams, oxidative stress in the dams, fetuses and placenta as well as inflammation and high levels of HIF-1? in the placenta. Pregnancy outcome of FFand FS-treated animals was worse than that of IPC-treated animals. PMID:23547731

  10. Transport Kinetics of Iron Chelators and Their Chelates in Caco-2 Cells

    Microsoft Academic Search

    Xi-Ping Huang; M. Spino; J. J. Thiessen

    2006-01-01

    \\u000a Purpose  Caco-2 monolayers were used to contrast the bidirectional transport of iron chelators and their chelates and to estimate fundamental\\u000a kinetics associated with their intestinal absorption.\\u000a \\u000a \\u000a \\u000a Methods  Bidirectional transport was studied at 37C and pH 7.4 using 500-?M concentrations. Monolayer integrity was tested via transepithelial\\u000a electrical resistance and sodium fluorescein permeability. Apical and basolateral analysis provided mass balance evidence.\\u000a Apparent permeability coefficient

  11. Chelators whose affinity for calcium is decreased by illumination

    NASA Technical Reports Server (NTRS)

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

    1987-01-01

    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.

  12. The iron chelating cardioprotective prodrug dexrazoxane does not affect the cell growth inhibitory effects of bleomycin.

    PubMed

    Wu, Xing; Patel, Daywin; Hasinoff, Brian B

    2004-11-01

    The clinical use of bleomycin is limited by a dose-dependent pulmonary toxicity. Bleomycin is thought to be growth inhibitory by virtue of its ability to oxidatively damage DNA through its complex with iron. Our previous preclinical studies showed that bleomycin-induced pulmonary toxicity can be reduced by pretreatment with the doxorubicin cardioprotective agent dexrazoxane. Dexrazoxane is thought to protect against iron-based oxygen radical damage through the iron chelating ability of its hydrolyzed metabolite ADR-925, an analog of ethylenediaminetetraacetic acid (EDTA). ADR-925 quickly and effectively displaced either ferrous or ferric iron from its complex with bleomycin. This result suggests that dexrazoxane may have the potential to antagonize the iron-dependent growth inhibitory effects of bleomycin. A study was undertaken to determine if dexrazoxane could antagonize bleomycin-mediated cytotoxicity using a CHO-derived cell line (DZR) that was highly resistant to dexrazoxane through a threonine-48 to isoleucine mutation in topoisomerase IIalpha. Dexrazoxane is also a cell growth inhibitor that acts through its ability to inhibit the catalytic activity of topoisomerase II. Thus, the DZR cell line allowed us to examine the cell growth inhibitory effects of bleomycin in the presence of dexrazoxane without the confounding effect of dexrazoxane inhibiting cell growth. The cell growth inhibitory effects of bleomycin were unaffected by pretreating DZR cells with dexrazoxane. These results suggest that dexrazoxane may be clinically used in combination with bleomycin as a pulmonary protective agent without adversely affecting the antitumor activity of bleomycin. PMID:15522409

  13. Chelators as antidotes of metal toxicity: therapeutic and experimental aspects.

    PubMed

    Blanusa, Maja; Varnai, Veda M; Piasek, Martina; Kostial, Krista

    2005-01-01

    The effects of chelating drugs used clinically as antidotes to metal toxicity are reviewed. Human exposure to a number of metals such as lead, cadmium, mercury, manganese, aluminum, iron, copper, thallium, arsenic, chromium, nickel and platinum may lead to toxic effects, which are different for each metal. Similarly the pharmacokinetic data, clinical use and adverse effects of most of the chelating drugs used in human metal poisoning are also different for each chelating drug. The chelating drugs with worldwide application are dimercaprol (BAL), succimer (meso-DMSA), unithiol (DMPS), D-penicillamine (DPA), N-acetyl-D-penicillamine (NAPA), calcium disodium ethylenediaminetetraacetate (CaNa(2)EDTA), calcium trisodium or zinc trisodium diethylenetriaminepentaacetate (CaNa(3)DTPA, ZnNa(3)DTPA), deferoxamine (DFO), deferiprone (L1), triethylenetetraamine (trientine), N-acetylcysteine (NAC), and Prussian blue (PB). Several new synthetic homologues and experimental chelating agents have been designed and tested in vivo for their metal binding effects. These include three groups of synthetic chelators, namely the polyaminopolycarboxylic acids (EDTA and DTPA), the derivatives of BAL (DMPS, DMSA and mono- and dialkylesters of DMSA) and the carbodithioates. Many factors have been shown to affect the efficacy of the chelation treatment in metal poisoning. Within this context it has been shown in experiments using young and adult animals that metal toxicity and chelation effects could be influenced by age. These findings may have a bearing in the design of new therapeutic chelation protocols for metal toxicity. PMID:16305472

  14. Metal regeneration of iron chelates in nitric oxide scrubbing

    DOEpatents

    Chang, Shih-Ger (El Cerrito, CA); Littlejohn, David (Oakland, CA); Shi, Yao (Berkeley, CA)

    1997-08-19

    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.degree. and 90.degree. 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.

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

    PubMed

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

    2008-02-01

    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

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

    Microsoft Academic Search

    Ismaele Jacques; Norma W. Andrews; Chau Huynh

    2010-01-01

    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

  17. Identification and characterization of agent for reductive dechlorination in mixtures of ferrous iron and Portland cement 

    E-print Network

    Ko, Sae Bom

    2001-01-01

    IDENTIFICATION AND CHARACTERIZATION OF AGENT FOR REDUCTIVE DECHLORINATION IN MIXTURES OF FERROUS IRON AND PORTLAND CEMENT A Thesis by SAE BOM KO Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment... of the requirements for the degree of MASTER OF SC1ENCE December 2001 Major Subject: Civil Engineering IDENTIFICATION AND CHARACTERIZATION OF AGENT FOR REDUCTIVE DECHLORINATION IN MIXTURES OF FERROUS IRON AND PORTLAND CEMENT A Thesis by SAE BOM KO Submitted...

  18. An enzymatic approach to bifunctional chelating agents.

    PubMed

    Minazzi, Paolo; Lattuada, Luciano; Menegotto, Ivan G; Giovenzana, Giovanni B

    2014-09-21

    Bifunctional chelating agents (BFCAs) combine the complexing properties of a multidentate ligand with the presence of a free reactive functional group, mainly devoted to conjugation purposes. Indeed, products obtained by conjugation of a BFCA to a biomolecule and coordination of a suitable metal ion are widely applied in medicine nowadays as diagnostic and therapeutic agents. BFCAs are generally prepared through multi-step syntheses and with extensive application of protection-deprotection strategies, due to the large number of functional groups involved. Hydrolytic enzymes, with their unique chemoselectivity, provided the best results in the preparation of three different BFCAs based on very useful and well known ligand platforms. PMID:25060174

  19. Friction and wear of some ferrous-base metallic glasses

    NASA Technical Reports Server (NTRS)

    Miyoshi, K.; Buckley, D. H.

    1983-01-01

    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.

  20. Cell cycle synchronisation by 3-hydroxypyridin-4-one iron chelators

    Microsoft Academic Search

    Katharine P. Hoyes; John B. Porter

    1996-01-01

    We describe a protocol for the synchronisation of normal and tumour cells grown in suspension cultures using 3-hydroxypyridin-4-one iron chelators. These compounds inhibit ribonucleotide reductase, one of the rate limiting enzymes in DNA synthesis, and so block the cell cycle in late G1 phase. After removal of the chelator or repletion of cellular iron, cells progress through the cycle and

  1. Influence of iron chelation on the antioxidant activity of flavonoids

    Microsoft Academic Search

    Saskia A. B. E van Acker; Georgette Plemper van Balen; Aalt Bast; Wim J. F van der Vijgh

    1998-01-01

    The antioxidant activity of flavonoids is believed to be caused by a combination of iron chelation and free radical scavenging activities. Several authors have attempted to separate the iron chelation and scavenging activity of flavonoids in order to study these processes individually. There are, however, several contradictions in the literature, and the outcome largely depends on the experimental conditions and

  2. Reusable chelating resins concentrate metal ions from highly dilute solutions

    NASA Technical Reports Server (NTRS)

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

    1966-01-01

    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.

  3. Iron chelators induce autophagic cell death in multiple myeloma cells.

    PubMed

    Pullarkat, Vinod; Meng, Zhuo; Donohue, Cecile; Yamamoto, Vicky N; Tomassetti, Sarah; Bhatia, Ravi; Krishnan, Amrita; Forman, Stephen J; Synold, Timothy W

    2014-08-01

    We examined the antineoplastic effects of the iron chelators, deferasirox and deferoxamine in multiple myeloma cell lines as well as primary myeloma cells. These iron chelators showed marked antiproliferative activity as well as cytotoxicity toward myeloma cell lines and deferasirox was cytotoxic to bone marrow plasma cells from myeloma patients. We also demonstrate that autophagy induced by iron deprivation is the dominant mechanism that mediates the cytotoxicity of iron chelators in multiple myeloma. Exposure to iron chelators led to repression of mTOR signaling as evidenced by decreased phosphorylation of its target p70S6 kinase. Iron chelation, in particular with deferasirox has the potential to be readily translated to a clinical trial for multiple myeloma. PMID:24998390

  4. Clawing Back: Broadening the Notion of Metal Chelators in Medicine

    PubMed Central

    Franz, Katherine J.

    2013-01-01

    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

  5. Chelating Agents and the Regulation of Metal Ions

    PubMed Central

    Bulman, Robert A.

    1994-01-01

    Up to about the early 1980s it was perhaps still possible to summarize in a review of a moderate length the development of the medicinal applications of chelation chemistry and the exploitation of such chemistry in regulating the metal ion concentrations in the body. However, in the last few years there has a great surge in the development of chelation chemistry and its usage in medicine and related areas of life sciences research. It is no longer the case that such a review primarily concentrates upon the use of chelating agents in removing toxic metals from the body but it must now cover the use of chelating agents in the imaging procedures nuclear medicine and magnetic resonance imaging (MRI), the use of chelating agents in unravelling the biochemistry of reactive oxidative species (ROS) and the control and measurement of intracellular calcium ions. It is in the recent applications that there have been the greatest developments over the last ten years. PMID:18476223

  6. Chelation of cadmium by combining deferasirox and deferiprone in rats.

    PubMed

    Jamilaldin Fatemi, S; Saljooghi, Amir Shokooh; Balooch, Faezeh Dahooee; Iranmanesh, Marzieh; Golbafan, Mohammad Reza

    2011-05-01

    The present research aimed to characterize the potential efficiency of two chelators after cadmium administration for 60 days following two dose levels of 20 and 40 mg/kg body weight daily to male rats. However, the hypothesis that the two chelators might be more efficient as combined therapy than as single therapy in removing cadmium from the body was considered. In this way, two known chelators deferasirox and deferiprone (L(1)) were chosen and tested in the acute rat model. Two chelators were given orally as a single or combined therapy for the period of a week. Cadmium and iron concentrations in various tissues were determined by graphite furnace and flame atomic absorption spectrometry methods, respectively. The combined chelation therapy results show that Deferasirox and L(1) are able to remove cadmium ions from the body while iron concentration returned to the normal level and symptoms are also decreased. PMID:21245204

  7. Ultrafine Particulate Ferrous Iron and Anthracene Associations with Mitochondrial Dysfunction

    SciTech Connect

    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

    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).

  8. In vitro chelating, cytotoxicity, and blood compatibility of degradable poly(ethylene glycol)-based macromolecular iron chelators

    Microsoft Academic Search

    Nicholas A. A. Rossi; Ibrahim Mustafa; John K. Jackson; Helen M. Burt; Sonja A. Horte; Mark D. Scott; Jayachandran N. Kizhakkedathu

    2009-01-01

    Desferrioxamine (DFO) is used to treat an excess accumulation of iron in the body and is currently the most commonly used iron chelator for the treatment of ‘iron overload’ disorder. However, the disadvantages of DFO surround its high toxicity and very short plasma half-life. Here, the detailed in vitro evaluation of a novel class of high molecular weight iron chelators

  9. Studies on intermolecular interactions of metal chelate complexes. Part X. Interactions of metal chelates with ozone

    Microsoft Academic Search

    Nicola D. Yordanov; Yulian Karadzhov

    1985-01-01

    The interactions of more than forty metal chelate complexes, dithiocarbamates, dithiophosphates and acetylacetonates, with ozone are studied in homogeneous phase and the stoichiometry and the rate constants of the reactions estimated. Most powerful ozone deactivators are nickel(II) and copper(II) dithiocarbamate and dithiophosphate complexes interacting with 6.5 moles ozone per mole of the ligand with rate constant >06m · I-1 ·

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

    PubMed Central

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

    2014-01-01

    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

  11. Chelation: harnessing and enhancing heavy metal detoxification--a review.

    PubMed

    Sears, Margaret E

    2013-01-01

    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

  12. Synthetic and natural iron chelators: therapeutic potential and clinical use

    PubMed Central

    Hatcher, Heather C; Singh, Ravi N; Torti, Frank M; Torti, Suzy V

    2013-01-01

    Iron-chelation therapy has its origins in the treatment of iron-overload syndromes. For many years, the standard for this purpose has been deferoxamine. Recently, considerable progress has been made in identifying synthetic chelators with improved pharmacologic properties relative to deferoxamine. Most notable are deferasirox (Exjade®) and deferiprone (Ferriprox®), which are now available clinically. In addition to treatment of iron overload, there is an emerging role for iron chelators in the treatment of diseases characterized by oxidative stress, including cardiovascular disease, atherosclerosis, neurodegenerative diseases and cancer. While iron is not regarded as the underlying cause of these diseases, it does play an important role in disease progression, either through promotion of cellular growth and proliferation or through participation in redox reactions that catalyze the formation of reactive oxygen species and increase oxidative stress. Thus, iron chelators may be of therapeutic benefit in many of these conditions. Phytochemicals, many of which bind iron, may also owe some of their beneficial properties to iron chelation. This review will focus on the advances in iron-chelation therapy for the treatment of iron-overload disease and cancer, as well as neurodegenerative and chronic inflammatory diseases. Established and novel iron chelators will be discussed, as well as the emerging role of dietary plant polyphenols that effectively modulate iron biochemistry. PMID:21425984

  13. [Peroxidation of lecithin in the presence of dihydroquercetin and its complex with ferrous iron ions].

    PubMed

    Shatalin, Iu V; Shmarev, A N

    2010-01-01

    The ability of the flavonoid dihydroquercetin to prevent or accelerate the accumulation of reactive oxygen species and the metabolites of oxidative stress, carbonyl compounds has been studied. It has been shown on a model of oxidation of lecithin that dihydroquercetin exhibits a prooxidant effect in the alkaline region of pH, whereas at neutral and acidic pH values dihydroquercetin is an effective antioxidant. In the presence of ferrous iron ions, which catalyze the Fenton's reaction, dihydroquercetin forms a complex with metal that shows the antioxidant activity in the region of high pH values. It has been found that the oxidation of lecithin in the presence of 20-200 microM ferrous iron is inhibited by dihydroquercetin to a concentration of 3.2 mM. At higher concentration of dihydroquercetin in the presence of ferrous iron, the accumulation of malonic dialdehyde occurs, indicating the presence of the prooxidant activity of dihydroquercetin. PMID:20184144

  14. Lactoferrin efficacy versus ferrous sulfate in curing iron disorders in pregnant and non-pregnant women.

    PubMed

    Paesano, R; Berlutti, F; Pietropaoli, M; Goolsbee, W; Pacifici, E; Valenti, P

    2010-01-01

    Iron homeostasis in pregnancy compensates for increased iron requirements and in women of child-bearing age for iron loss in menses. Oral administration of ferrous sulfate, prescribed to cure iron deficiency (ID) and ID anemia (IDA), often fails to increase hematological parameters and causes adverse effects. Recently, we demonstrated safety and efficacy of bovine lactoferrin (bLf) in pregnant women suffering from ID/IDA. Two clinical trials were conducted on pregnant and non-pregnant women of child-bearing age suffering from ID/IDA. In both trials, women received oral administration of bLf 100 mg/twice/day (Arm A), or ferrous sulfate 520 mg/day (Arm B). Hematological parameters, serum IL-6 and prohepcidin were assayed before and after therapy. Unlike ferrous sulfate, bLf increased hematological parameters (P less than 0.0001). In pregnant women, bLf decreased serum IL-6 (P less than 0.0001), and increased prohepcidin (P=0.0007). In non-pregnant women bLf did not change the low IL-6 levels while it increased prohepcidin (P less than 0.0001). Ferrous sulfate increased IL-6 (P less than 0.0001) and decreased prohepcidin (P=0.093). bLf established iron homeostasis by modulating serum IL-6 and prohepcidin synthesis, whereas ferrous sulfate increased IL-6 and failed to increase hematological parameters and prohepcidin. bLf is a more effective and safer alternative than ferrous sulfate for treating ID and IDA. PMID:20646353

  15. Ferrous iron oxidation by foam immobilized Acidithiobacillus ferrooxidans: Experiments and modeling.

    PubMed

    Jaisankar, S; Modak, J M

    2009-01-01

    Ferrous iron bio-oxidation by Acidithiobacillus ferrooxidans immobilized on polyurethane foam was investigated. Cells were immobilized on foams by placing them in a growth environment and fully bacterially activated polyurethane foams (BAPUFs) were prepared by serial subculturing in batches with partially bacterially activated foam (pBAPUFs). The dependence of foam density on cell immobilization process, the effect of pH and BAPUF loading on ferrous oxidation were studied to choose operating parameters for continuous operations. With an objective to have high cell densities both in foam and the liquid phase, pretreated foams of density 50 kg/m(3) as cell support and ferrous oxidation at pH 1.5 to moderate the ferric precipitation were preferred. A novel basket-type bioreactor for continuous ferrous iron oxidation, which features a multiple effect of stirred tank in combination with recirculation, was designed and operated. The results were compared with that of a free cell and a sheet-type foam immobilized reactors. A fivefold increase in ferric iron productivity at 33.02 g/h/L of free volume in foam was achieved using basket-type bioreactor when compared to a free cell continuous system. A mathematical model for ferrous iron oxidation by Acidithiobacillus ferrooxidans cells immobilized on polyurethane foam was developed with cell growth in foam accounted by an effectiveness factor. The basic parameters of simulation were estimated using the experimental data on free cell growth as well as from cell attachment to foam under nongrowing conditions. The model predicted the phase of both oxidation of ferrous in shake flasks by pBAPUFs as well as by fully activated BAPUFs for different cell loadings in foam. Model for stirred tank basket bioreactor predicted within 5% both transient and steady state of the experiments closely for the simulated dilution rates. Bio-oxidation at high Fe(2+) concentrations were simulated with experiments when substrate and product inhibition coefficients were factored into cell growth kinetics. PMID:19610075

  16. New insights into novel inhibitors against deoxyhypusine hydroxylase from plasmodium falciparum: compounds with an iron chelating potential.

    PubMed

    von Koschitzky, Imke; Gerhardt, Heike; Lämmerhofer, Michael; Kohout, Michal; Gehringer, Matthias; Laufer, Stefan; Pink, Mario; Schmitz-Spanke, Simone; Strube, Christina; Kaiser, Annette

    2015-06-01

    Deoxyhypusine hydroxylase (DOHH) is a dinuclear iron enzyme required for hydroxylation of the aminobutyl side chain of deoxyhypusine in eukaryotic translation initiation factor 5A (eIF-5A), the second step in hypusine biosynthesis. DOHH has been recently identified in P. falciparum and P. vivax. Both enzymes have very peculiar features including E-Z type HEAT-like repeats and a diiron centre in their active site. Both proteins share only 26 % amino acid identity to the human paralogue. Hitherto, no X-ray structure exists from either enzyme. However, structural predictions based on the amino acid sequence of the active site in comparison to the human enzyme show that four conserved histidine and glutamate residues provide the coordination sites for chelating the ferrous iron ions. Recently, we showed that P. vivax DOHH is inhibited by zileuton (N-[1-(1-benzothien-2-yl)ethyl]-N-hydroxyurea), a drug that is known for inhibiting human 5-lipoygenase (5-LOX) by the complexation of ferrous iron. A novel discovery program was launched to identify inhibitors of the P. falciparum DOHH from the Malaria Box, consisting of 400 chemical compounds, which are highly active in the erythrocytic stages of Malaria infections. In a first visual selection for potential ligands of ferrous iron, three compounds from different scaffold classes namely the diazonapthyl benzimidazole MMV666023 (Malaria Box plate A, position A03), the bis-benzimidazole MMV007384 (plate A, position B08), and a 1,2,5,-oxadiazole MMV665805 (plate A, position C03) were selected and subsequently evaluated in silico for their potential to complex iron ions. As a proof of principle, a bioanalytical assay was performed and the inhibition of hypusine biosynthesis was determined by GC-MS. All tested compounds proved to be active in this assay and MMV665805 exhibited the strongest inhibitory effect. Notably, the results were in accordance with the preliminary quantum-mechanical calculations suggesting the strongest iron complexation capacity for MMV665805. This compound might be a useful tool as well as a novel lead structure for inhibitors of P. falciparum DOHH. PMID:25715757

  17. Synthesis of magnetite nanoparticles by thermal decomposition of ferrous oxalate dihydrate

    Microsoft Academic Search

    Andre Angermann; Jörg Töpfer

    2008-01-01

    Two different polymorphs of ferrous oxalate dihydrate were synthesized by precipitation of ferrous ions with oxalic acid:\\u000a ?-Fe(C2O4) · 2H2O with a monoclinic unit cell is obtained after precipitation and ageing at 90 °C, whereas the orthorhombic ?-type is formed\\u000a after precipitation at room temperature. The morphology of the oxalate crystals can be tailored from prismatic crystals of\\u000a the ?-polymorph over star-like aggregates

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

    Microsoft Academic Search

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

    2007-01-01

    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

  19. Chelators at the cancer coalface: desferrioxamine to Triapine and beyond.

    PubMed

    Yu, Yu; Wong, Jacky; Lovejoy, David B; Kalinowski, Danuta S; Richardson, Des R

    2006-12-01

    The importance of iron and copper in cancer biology has been well established. Iron plays a fundamental role in cellular proliferation and copper has been shown to be a significant cofactor for angiogenesis. Early observations with the chelator used for the treatment of iron overload, desferrioxamine, showed that it had promise as an anticancer agent. These results sparked great interest in the possibility of developing more effective iron chelators for cancer therapy. The recent entry into clinical trials of the iron-binding drug, Triapine, provides evidence of the potential of this antitumor strategy. Likewise, chelators originally designed to treat disorders of copper overload, such as penicillamine, trientine, and tetrathiomolybdate, have also emerged as potential anticancer drugs, as they are able to target the key angiogenic cofactor, copper. In this review, we will discuss the development of these and other chelators that show potential as anticancer agents. PMID:17145804

  20. Metal chelate process to remove pollutants from fluids

    DOEpatents

    Chang, S.G.T.

    1994-12-06

    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.

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

    DOEpatents

    Raymond, K.; Xu, J.

    1999-04-06

    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.

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

    DOEpatents

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

    1999-01-01

    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.

  3. Comparing potential copper chelation mechanisms in Parkinson's disease protein

    NASA Astrophysics Data System (ADS)

    Rose, Frisco; Hodak, Miroslav; Bernholc, Jerry

    2011-03-01

    We have implemented the nudged elastic band (NEB) as a guided dynamics framework for our real-space multigrid method of DFT-based quantum simulations. This highly parallel approach resolves a minimum energy pathway (MEP) on the energy hypersurface by relaxing intermediates in a chain-of-states. As an initial application we present an investigation of chelating agents acting on copper ion bound to ? -synuclein, whose misfolding is implicated in Parkinson's disease (PD). Copper ions are known to act as highly effective misfolding agents in a-synuclein and are thus an important target in understanding PD. Furthermore, chelation therapy has shown promise in the treatment of Alzheimer's and other neuro-degenerative diseases with similar metal-correlated pathologies. At present, our candidate chelating agents include nicotine, curcumin and clioquinol. We examine their MEP activation barriers in the context of a PD onset mechanism to assess the viability of various chelators for PD remediation.

  4. Cell assay using a two-photon-excited europium chelate

    PubMed Central

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

    2011-01-01

    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

  5. Current status of iron overload and chelation with deferasirox

    Microsoft Academic Search

    V. P. Choudhry; Rahul Naithani

    2007-01-01

    A large number of complications in thalassemia major are due mainly to iron overload. Deferoxamine in iron-overloaded patients\\u000a has established that chelation therapy, when given at an adequate dose, reduces iron-related complications. Parenteral administration\\u000a and the daily nuisance of an infusion pump hinder the optimal compliance. Deferiprone is moderately effective oral iron chelator.\\u000a Arthralgia and cytopenias constitute the main side

  6. Light Emitting Diodes Prepared from Terbium?Immobilized Polyurea Chelates

    Microsoft Academic Search

    Jeremiah K. Mwaura; Mathew K. Mathai; Changqing Chen; Fotios Papadimitrakopoulos

    2003-01-01

    This article describes the synthesis and application of poly(1,4?phenylene?2,6?pyridylurea) (MCPU) as a charge transporting and rare earth metal chelating host matrix for organic light emitting diodes (OLEDs). The chelation between MCPU and Terbium (Tb) (the rare earth metal used in this study), is facile in nature and persists in thin films obtained by spin coating onto various substrates. Multiple polymer

  7. Chelation of bismuth by combining desferrioxamine and deferiprone in rats.

    PubMed

    Tubafard, S; Fatemi, S J

    2008-05-01

    Consumption and production of bismuth compounds are increasing, however, a little information on the toxic effect and also the effective method in removal of bismuth compounds are available. The present research aimed to characterize the potential efficiency of two chelators after bismuth administration for 55A days following two dose levels of 20 and 40A mg/kg body weight daily to male rats. However, we found abnormalities after bismuth administration in clinical signs, such as body weight, kidneys and liver damages, a black line on gums and skin reactions. Furthermore, the hypothesis that the two chelators might be more efficient as combined therapy than as single therapy in removing bismuth from the body was considered. Along this line, two known chelators deferiprone (1, 2-dimethy1-3-hydroxypyride-4-one, L(1)) and desferrioxamine (DFO) were chosen and tested in the acute rat model. Chelators were given orally (L(1)) or intraperitoneally (DFO) as a single or combined therapy for the period of a week. Doses of L(1) and DFO were 110A mg/kg body weight in experiments. Bismuth and iron concentrations in various tissues were determined by graphite furnace and flame atomic absorption spectrometry, respectively. The combined chelation therapy results show that DFO and L(1) are able to remove bismuth ions from the body, whereas iron concentration returned to the normal level and symptoms are also decreased. DFO was more effective than L1 in reducing bismuth concentration in tissues. The efficiency of DFOA +A L(1) is more than DFO or L(1) in removing bismuth from organs. Our results are indicative that the design procedure might be useful for preliminary in-vivo testing of the efficiency of chelating agents. Results of combined chelators' treatment should be confirmed in a different experimental model before extrapolation to other systems. This testing procedure of course does not provide all the relevant answers for efficiency of chelating agents in bismuth toxicity. PMID:19022876

  8. New iron chelators in anthracycline-induced cardiotoxicity

    Microsoft Academic Search

    Helena Kaiserová; TomᚠŠim?nek; Martin Št?rba; Gertjan J. M. den Hartog; Ladislava Schröterová; Olga Popelová; Vladimír Geršl; Eva Kvasni?ková; Aalt Bast

    2007-01-01

    The use of anthracycline anticancer drugs is limited by a cumulative, dose-dependent cardiac toxicity. Iron chelation has\\u000a long been considered as a promising strategy to limit this unfavorable side effect, either by restoring the disturbed cellular\\u000a iron homeostasis or by removing redox-active iron, which may promote anthracycline-induced oxidative stress. Aroylhydrazone\\u000a lipophilic iron chelators have shown promising results in the rabbit

  9. Phenolic ethylenediamine derivatives: a study of orally effective iron chelators

    Microsoft Academic Search

    C. Hershko; R. W. Grady; G. Link

    1984-01-01

    Of 35 potential iron chelators screened for in vivo activity in rats, a group of phenolic compounds with excellent chelating properties were identified. These included N,N'-ethylene-bis(o-hydroxyphenylglycine) (EHPG), N,N'-Bis(o-hydroxybenzyl)-ethylenediamine diacetic acid (HBED), and their respective dimethyl esters (dmEHPG and dmHBED). All four phenolic compounds produced a marked increase in the fecal excretion of hepatocellular radioiron. This amounted to 42% of total

  10. Iron Chelation and the Ventilatory Response to Hypoxia

    Microsoft Academic Search

    Mieczyslaw Pokorski; Justyna Antosiewicz; Camillo Di Giulio; Sukhamay Lahiri

    Chelation of iron in in vitro carotid body emulates the effects of hypoxia. The role iron plays in in vivo ventilatory responses\\u000a is unclear. In the current study we addressed this issue by examining the effects of chronic iron chelation on the hypoxic\\u000a ventilatory response in 9 conscious Wistar rats. Acute responses to 14 and 9% O2in N2 were recorded

  11. Iron chelators as therapeutic agents against Pneumocystis carinii.

    PubMed Central

    Weinberg, G A

    1994-01-01

    Iron plays a critical role in host-parasite interactions, and iron chelators have been demonstrated to serve as effective adjunct therapeutic agents against malaria. The effects of the parenteral iron chelator deferoxamine (DFO) on the growth of rat-derived Pneumocystis carinii were studied in a human fibroblast cell culture model and in two in vivo models of experimental infection. In addition, the effects of the investigational oral iron chelator CP20 and its 3-hydroxypyridin-4-one analogs CP51, CP94, and CP96 on the growth of P. carinii in vitro were assessed. DFO suppressed the growth of P. carinii in vitro in a dose-dependent manner, and daily injections of DFO markedly reduced the intensity of P. carinii infection in both mice and rats. Cell cultures treated with iron chelators that are administered orally to humans also showed substantial P. carinii growth inhibition. Reduction of P. carinii numbers after iron chelator therapy correlated with alterations in P. carinii morphology, as viewed by transmission electron microscopy. Since the use of current anti-P. carinii drugs is limited by toxicity or incomplete efficacy, or both, the role of iron chelation as adjunctive anti-P. carinii chemotherapy merits additional investigation. Images PMID:8067783

  12. Chelating ligands for nanocrystals' surface functionalization.

    PubMed

    Querner, Claudia; Reiss, Peter; Bleuse, Joël; Pron, Adam

    2004-09-22

    A new family of ligands for the surface functionalization of CdSe nanocrystals is proposed, namely alkyl or aryl derivatives of carbodithioic acids (R-C(S)SH). The main advantages of these new ligands are as follows: they nearly quantitatively exchange the initial surface ligands (TOPO) in very mild conditions; they significantly improve the resistance of nanocrystals against photooxidation because of their ability of strong chelate-type binding to metal atoms; their relatively simple preparation via Grignard intermediates facilitates the development of new bifunctional ligands containing, in addition to the anchoring carbodithioate group, a second function, which enables the grafting of molecules or macromolecules of interest on the nanocrystal surface. To give an example of this approach, we report, for the first time, the grafting of an electroactive oligomer from the polyaniline family-aniline tetramer-on CdSe nanocrystals after their functionalization with 4-formyldithiobenzoic acid. The grafting proceeds via a condensation reaction between the aldehyde group of the ligand and the terminal primary amine group of the tetramer. The resulting organic/inorganic hybrid exhibits complete extinction of the fluorescence of its constituents, indicating efficient charge or energy transfer between the organic and the inorganic semiconductors. PMID:15366904

  13. Use of > 1:1 Chelator:Iron Ratios and Strong Iron(III) Chelators in Hydroponic Solutions for Barley

    Microsoft Academic Search

    Paul F. Bell; G. L. Kerven; D. G. Edwards; C. J. Asher

    2005-01-01

    This study examined two guidelines for preparing hydroponic solutions to ensure adequate iron (Fe) for Poaceae plants: (1) not to add chelator in excess of Fe concentrations and (2) to use only weaker forms of Fe(III) chelators. Barley was grown in low-Fe solutions for 9 d and transferred to Fe-spiked nutrient solutions at pH 8.1 containing ligand:Fe ? M concentrations

  14. Effective chelation of iron in beta thalassaemia with the oral chelator 1,2-dimethyl-3-hydroxypyrid-4-one

    Microsoft Academic Search

    G J Kontoghiorghes; M A Aldouri; A V Hoffbrand; J Barr; B Wonke; T Kourouclaris; L Sheppard

    1987-01-01

    The main iron chelator used for transfusional iron overload is desferrioxamine, which is expensive, has toxic side effects, and has to be given subcutaneously. An orally active iron chelator is therefore required. The effects of oral 1,2-dimethyl-3-hydroxypyrid-4-one on urinary iron excretion were studied in eight patients who had received multiple transfusions: four had myelodysplasia and four beta thalassaemia major. Different

  15. ELECTRODE MEASUREMENT OF REDOX POTENTIAL IN ANAEROBIC FERRIC/FERROUS CHLORIDE SYSTEMS

    EPA Science Inventory

    The behaviour of two inert redox electrodes (Pt and wax-impregnated graphite) was investigated in anaerobic ferrous and ferric chloride solutions in order to establish if these electrodes respond to the Fe3+/Fe2+ couple in a Nernstian manner. A new method fo...

  16. ELECTRODE MEASUREMENT OF REDOX POTENTIAL IN ANAEROBIC FERRIC/FERROUS CHLORIDE SYSTEMS

    EPA Science Inventory

    The behavior of two inert redox electrodes (Pt and wax-impregnated graphite) was investigated in anaerobic ferrous and ferric chloride solutions in order to establish if these electrodes respond to the FE3/Fe2+ couple in a Nernstian nanner. ew method for determining dissolved fer...

  17. Sintering of powder mixtures and the growth of ferrous powder metallurgy

    Microsoft Academic Search

    K. S Narasimhan

    2001-01-01

    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;

  18. Energy conservation and efficiency in Giprokoks designs at Ukrainian ferrous-metallurgical enterprises

    SciTech Connect

    M.I. Fal'kov [Giprokoks, the State Institute for the Design of Coke-Industry Enterprises, Kharkov (Ukraine)

    2009-07-15

    Energy conditions at Ukrainian ferrous-metallurgical enterprises are analyzed. Measures to boost energy conservation and energy efficiency are proposed: specifically, the introduction of systems for dry slaking of coke; and steam-gas turbines that employ coke-oven gas or a mixture of gases produced at metallurgical enterprises. Such turbines may be built from Ukrainian components.

  19. Iron Bioavailability from Pate Enriched with Encapsulated Ferric Pyrophosphate or Ferrous Gluconate in Rats

    Microsoft Academic Search

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

    2007-01-01

    Fortifying food with iron has been widely studied as a strategy to prevent iron deficiency anaemia. This work comparatively assessed the bioavailability of two forms of iron, ferrous gluconate or ferric pyrophosphate encapsulated in liposomes (lipofer®), when used as fortificants in meat pate. Three groups of growing rats consumed during 28 days either a control diet (AIN-93G), or two diets

  20. Biological oxidation of ferrous sulphate by Thiobacillus ferrooxidans: a review on the kinetic aspects

    Microsoft Academic Search

    M. Nemati; S. T. L. Harrison; G. S. Hansford; C. Webb

    1998-01-01

    Biological oxidation of ferrous sulphate by Thiobacillus ferrooxidans has proved to be a significant step in the bioleaching of sulphide minerals and treatment of acid mine drainage. The same bioreaction also has beneficial applications in the desulphurization of coal and removal of hydrogen sulphide from gaseous effluents. Owing to the numerous potential industrial applications, the process of biocatalytic oxidation of

  1. Health risk for children from lead and cadmium near a non-ferrous smelter in Bulgaria

    Microsoft Academic Search

    A. B. Fischer; R. Georgieva; V. Nikolova; J. Halkova; A. Bainova; V. Hristeva; D. Penkov; D. Alandjiisk

    2003-01-01

    In an interdisciplinary approach the exposure to lead and cadmium of the population living in the vicinity of a Bulgarian non-ferrous metallurgical plant was studied to determine the routes of exposure. Two exposed villages situated 4 and 6 km SW and W, respectively, – in the plume of the plant's emissions – and a village for comparison situated 14 km

  2. Ceric and ferrous dosimeters show precision for 50-5000 rad range

    NASA Technical Reports Server (NTRS)

    Frigerio, N. A.; Henry, V. D.

    1968-01-01

    Ammonium thiocyanate, added to the usual ferrous sulfate dosimeter solution, yielded a very stable, precise and temperature-independent system eight times as sensitive as the classical Fricke system in the 50 to 5000 rad range. The ceric dosimeters, promising for use in mixed radiation fields, respond nearly independently of LET.

  3. COMBINATION LIMESTONE-LIME NEUTRALIZATION OF FERROUS IRON ACID MINE DRAINAGE

    EPA Science Inventory

    Studies were conducted on ferrous-iron acid mine drainage (AMD) treatment by a two-step neutralization process in which rock-dust limestone was mixed with the influent AMD and then hydrated lime was added in a polishing reactor. This combination treatment process resulted in reag...

  4. ANALYSIS OF FERRIC AND FERROUS IONS IN SOIL EXTRACTS BY ION CHROMATOGRAPHY

    EPA Science Inventory

    A method using ion chromatography (IC) for the analysis of ferrous (Fe 2+) and ferric (Fe 3+) ions in soil extracts has been developed. This method uses an ion exchange column with detection at 520 nm after post-column derivatization. Selectivity is achieved by using an anionic...

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

    Microsoft Academic Search

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

    2011-01-01

    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

  6. 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 ...

  7. Ferrous Carbonyl Dithiolates as Precursors to FeFe, FeCo, and FeMn Carbonyl Dithiolates

    PubMed Central

    2015-01-01

    Reported are complexes of the formula Fe(dithiolate)(CO)2(diphos) and their use to prepare homo- and heterobimetallic dithiolato derivatives. The starting iron dithiolates were prepared by a one-pot reaction of FeCl2 and CO with chelating diphosphines and dithiolates, where dithiolate = S2(CH2)22– (edt2–), S2(CH2)32– (pdt2–), S2(CH2)2(C(CH3)2)2– (Me2pdt2–) and diphos = cis-C2H2(PPh2)2 (dppv), C2H4(PPh2)2 (dppe), C6H4(PPh2)2 (dppbz), C2H4[P(C6H11)2]2 (dcpe). The incorporation of 57Fe into such building block complexes commenced with the conversion of 57Fe into 57Fe2I4(iPrOH)4, which then was treated with K2pdt, CO, and dppe to give 57Fe(pdt)(CO)2(dppe). NMR and IR analyses show that these complexes exist as mixtures of all-cis and trans-CO isomers, edt2– favoring the former and pdt2– the latter. Treatment of Fe(dithiolate)(CO)2(diphos) with the Fe(0) reagent (benzylideneacetone)Fe(CO)3 gave Fe2(dithiolate)(CO)4(diphos), thereby defining a route from simple ferrous salts to models for hydrogenase active sites. Extending the building block route to heterobimetallic complexes, treatment of Fe(pdt)(CO)2(dppe) with [(acenaphthene)Mn(CO)3]+ gave [(CO)3Mn(pdt)Fe(CO)2(dppe)]+ ([3d(CO)]+). Reduction of [3d(CO)]+ with BH4– gave the Cs-symmetric ?-hydride (CO)3Mn(pdt)(H)Fe(CO)(dppe) (H3d). Complex H3d is reversibly protonated by strong acids, the proposed site of protonation being sulfur. Treatment of Fe(dithiolate)(CO)2(diphos) with CpCoI2(CO) followed by reduction by Cp2Co affords CpCo(dithiolate)Fe(CO)(diphos) (4), which can also be prepared from Fe(dithiolate)(CO)2(diphos) and CpCo(CO)2. Like the electronically related (CO)3Fe(pdt)Fe(CO)(diphos), these complexes undergo protonation to afford the ?-hydrido complexes [CpCo(dithiolate)HFe(CO)(diphos)]+. Low-temperature NMR studies indicate that Co is the kinetic site of protonation. PMID:24803716

  8. Ferrous Carbonyl Dithiolates as Precursors to FeFe, FeCo, and FeMn Carbonyl Dithiolates.

    PubMed

    Carroll, Maria E; Chen, Jinzhu; Gray, Danielle E; Lansing, James C; Rauchfuss, Thomas B; Schilter, David; Volkers, Phillip I; Wilson, Scott R

    2014-02-24

    Reported are complexes of the formula Fe(dithiolate)(CO)2(diphos) and their use to prepare homo- and heterobimetallic dithiolato derivatives. The starting iron dithiolates were prepared by a one-pot reaction of FeCl2 and CO with chelating diphosphines and dithiolates, where dithiolate = S2(CH2)2 (2-) (edt(2-)), S2(CH2)3 (2-) (pdt(2-)), S2(CH2)2(C(CH3)2)(2-) (Me2pdt(2-)) and diphos = cis-C2H2(PPh2)2 (dppv), C2H4(PPh2)2 (dppe), C6H4(PPh2)2 (dppbz), C2H4[P(C6H11)2]2 (dcpe). The incorporation of (57)Fe into such building block complexes commenced with the conversion of (57)Fe into (57)Fe2I4( (i) PrOH)4, which then was treated with K2pdt, CO, and dppe to give (57)Fe(pdt)(CO)2(dppe). NMR and IR analyses show that these complexes exist as mixtures of all-cis and trans-CO isomers, edt(2-) favoring the former and pdt(2-) the latter. Treatment of Fe(dithiolate)(CO)2(diphos) with the Fe(0) reagent (benzylideneacetone)Fe(CO)3 gave Fe2(dithiolate)(CO)4(diphos), thereby defining a route from simple ferrous salts to models for hydrogenase active sites. Extending the building block route to heterobimetallic complexes, treatment of Fe(pdt)(CO)2(dppe) with [(acenaphthene)Mn(CO)3](+) gave [(CO)3Mn(pdt)Fe(CO)2(dppe)](+) ([3d(CO)](+)). Reduction of [3d(CO)](+) with BH4 (-) gave the C s -symmetric ?-hydride (CO)3Mn(pdt)(H)Fe(CO)(dppe) (H3d). Complex H3d is reversibly protonated by strong acids, the proposed site of protonation being sulfur. Treatment of Fe(dithiolate)(CO)2(diphos) with CpCoI2(CO) followed by reduction by Cp2Co affords CpCo(dithiolate)Fe(CO)(diphos) (4), which can also be prepared from Fe(dithiolate)(CO)2(diphos) and CpCo(CO)2. Like the electronically related (CO)3Fe(pdt)Fe(CO)(diphos), these complexes undergo protonation to afford the ?-hydrido complexes [CpCo(dithiolate)HFe(CO)(diphos)](+). Low-temperature NMR studies indicate that Co is the kinetic site of protonation. PMID:24803716

  9. Bifunctional Chelates Optimized for Molecular MRI

    PubMed Central

    2015-01-01

    Important requirements for exogenous dyes or contrast agents in magnetic resonance imaging (MRI) include an effective concentration of paramagnetic or superparamagnetic ions at the target to be imaged. We report the concise synthesis and characterization of several new enantiopure bifunctional derivatives of (?1R,?4R,?7R,?10R)-?1,?4,?7,?10-tetramethyl-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTMA) (and their 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) analogues as controls) that can be covalently attached to a contrast agent delivery system using either click or peptide coupling chemistry. Gd complexes of these derivatives can be attached to delivery systems while maintaining optimal water residence time for increased molecular imaging sensitivity. Long chain biotin (LC-biotin) derivatives of the Eu(III) and Gd(III) chelates associated with avidin are used to demonstrate higher efficiencies. Variable-temperature relaxometry, 17O NMR, and nuclear magnetic resonance dispersion (NMRD) spectroscopy used on the complexes and biotin–avidin adducts measure the influence of water residence time and rotational correlation time on constrained and unconstrained systems. The Gd(III)-DOTMA derivative has a shorter water residence time than the Gd(III)-DOTA derivative. Compared to the constrained Gd(III)-DOTA derivatives, the rotationally constrained Gd(III)-DOTMA derivative has ?40% higher relaxivity at 37 °C, which could increase its sensitivity as an MRI agent as well as reduce the dose of the targeting agent. PMID:24933389

  10. The magnesium chelation step in chlorophyll biosynthesis

    SciTech Connect

    Weinstein, J.

    1990-11-01

    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.

  11. Ferric-salicylaldehyde isonicotinoyl hydrazone, a synthetic iron chelate, alleviates defective iron utilization by reticulocytes of the Belgrade rat.

    PubMed

    Garrick, L M; Gniecko, K; Hoke, J E; al-Nakeeb, A; Ponka, P; Garrick, M D

    1991-03-01

    The Belgrade rat has a hypochromic, microcytic anemia inherited as an autosomal recessive mutation. Although transferrin binds normally to reticulocytes and internalizes normally, iron accumulation into cells and heme is much slower than normal. We have investigated the role of the transferrin cycle in this mutant by bypassing transferrin iron delivery with the iron chelate ferric salicylaldehyde isonicotinoyl hydrazone (Fe-SIH). Fe-SIH increases iron uptake into heme by Belgrade reticulocytes, restoring it almost to normal levels. This increase indicates that Fe-SIH delivers iron to a step in iron utilization that is after the Belgrade defect. Depleting reticulocytes of transferrin did not alter these observations. Failure to achieve above normal rates of iron incorporation could indicate damage due to chronic intracellular iron deficiency. Also, iron delivery by Fe-SIH restored globin synthesis to near-normal levels in Belgrade reticulocytes. The rates of glycine incorporation into porphyrin and heme in Belgrade reticulocytes incubated with Fe2-transferrin or Fe-SIH paralleled the rates of iron incorporation into heme. These data are consistent with the concept that iron availability limits protoporphyrin formation in rat reticulocytes. The protoporphyrin used for heme synthesis is provided by de novo synthesis and not by a pool of pre-existing protoporphyrin. The Belgrade defect occurs in the movement of iron from transferrin to a step prior to the ferrous state and insertion into heme. This defect diminishes the synthesis of heme and, consequently, that of protoporphyrin and globin. PMID:2022700

  12. Antiproliferative and iron chelating efficiency of the new bis-8-hydroxyquinoline benzylamine chelator S1 in hepatocyte cultures.

    PubMed

    Lescoat, Gérard; Léonce, Stéphane; Pierré, Alain; Gouffier, Lucie; Gaboriau, François

    2012-01-25

    If a new generation of iron chelators specifically devoted for cancer chemotherapy emerged these last years, any of them has not yet been approved at this time. Accordingly, there is a need to optimize new chelating molecules for iron chelation therapy and cancer treatment. So, the objective of the present investigation was to characterize the antiproliferative activity and the iron chelating capacity of the iron chelator S1 [bis-N-(8-hydroxyquinoline-5-ylmethyl)benzylamine]. Its effects were compared to O-trensox which binds ferric iron with a very high affinity (pFe(3+)=29.5). For this purpose, primary rat hepatocyte stimulated by EGF and human hepatoma HepaRG cell cultures were used. In these models, the anti-proliferative effect, the inhibition of DNA synthesis and the iron-chelating efficiency of increasing concentrations of S1 and O-trensox (0 up to 200 ?M) were investigated. In the two cell culture models, we observed that S1 was about 100 times more efficient than O-trensox and the antiproliferative effect of S1 in HepaRG cells appeared at concentrations as low as 0.1 ?M without cytotoxicity. Moreover, the stoichiometry of S1 for iron seemed to be in the range S1/Fe(3+)=1. Using the calcein fluorescence assay, we demonstrated that the affinity of S1 for iron was better than that of O-trensox since it was at least two times more effective to restore the fluorescence of calcein previously quenched by iron. So, the iron chelating efficiency of S1 could explain at least partially its higher anti-proliferative effect compared to O-trensox. Finally, these results suggest that molecules such as S1 may constitute a promising starting point to improve cancer treatment. PMID:22197641

  13. Ab Initio Coordination Chemistry for Nickel Chelation Motifs

    PubMed Central

    Jesu Jaya Sudan, R.; Lesitha Jeeva Kumari, J.; Sudandiradoss, C.

    2015-01-01

    Chelation therapy is one of the most appreciated methods in the treatment of metal induced disease predisposition. Coordination chemistry provides a way to understand metal association in biological structures. In this work we have implemented coordination chemistry to study nickel coordination due to its high impact in industrial usage and thereby health consequences. This paper reports the analysis of nickel coordination from a large dataset of nickel bound structures and sequences. Coordination patterns predicted from the structures are reported in terms of donors, chelate length, coordination number, chelate geometry, structural fold and architecture. The analysis revealed histidine as the most favored residue in nickel coordination. The most common chelates identified were histidine based namely HHH, HDH, HEH and HH spaced at specific intervals. Though a maximum coordination number of 8 was observed, the presence of a single protein donor was noted to be mandatory in nickel coordination. The coordination pattern did not reveal any specific fold, nevertheless we report preferable residue spacing for specific structural architecture. In contrast, the analysis of nickel binding proteins from bacterial and archeal species revealed no common coordination patterns. Nickel binding sequence motifs were noted to be organism specific and protein class specific. As a result we identified about 13 signatures derived from 13 classes of nickel binding proteins. The specifications on nickel coordination presented in this paper will prove beneficial for developing better chelation strategies. PMID:25985439

  14. Effective iron chelation practice for patients with ?-thalassemia major.

    PubMed

    Carson, Susan M; Martin, Marie B

    2014-02-01

    Chronic blood transfusion is the only treatment for severe anemia in patients with ?-thalassemia major. However, red blood cell transfusions lead to iron overload and subsequent organ damage because of the toxic effects of iron. The heart is particularly vulnerable to iron toxicity, and heart failure is the leading cause of death among these patients. Iron chelation therapy prevents or reverses iron loading, thereby reducing the risk of complications from excess iron. Serum ferritin and liver iron concentration often are used to gauge the risk of organ iron overload, but these measurements may not correlate well with cardiac iron load. Magnetic resonance imaging (MRI) is a noninvasive diagnostic tool that can provide a more direct measure of iron concentration in both the heart and liver. Cardiac iron determined by MRI is expressed as a function of T2*, in which higher values represent lower concentrations. Changes in T2* are used to assess the effectiveness of iron chelation and to adjust therapy. Early treatment and compliance are keys to successful therapy. Nursing strategies to optimize chelation therapy include identifying patients who are at risk for developing organ damage, developing chelation plans, promoting compliance, and educating patients. The efficacy and safety of iron chelators, as well as nursing best practices, are reviewed. PMID:24476732

  15. 3-hydroxy-2(1H)-pyridinone chelating agents

    DOEpatents

    Raymond, K.N.; Xu, J.

    1997-04-29

    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.

  16. 3-hydroxy-2(1H)-pyridinone chelating agents

    DOEpatents

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

    1997-01-01

    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.

  17. Essential Metalloelement Chelates Facilitate Repair of Radiation Injury

    PubMed Central

    Soderberg, Lee S. F.; Chang, Louis W.; Walker, Richard B.

    2001-01-01

    Treatment with essential metalloelement (Cu, Fe, Mn, and Zn) chelates or combinations of them before and/or after radiation injury is a useful approach to overcoming radiation injury. No other agents are known to increase survival when they are used to treat after irradiation, in a radiorecovery treatment paradigm. These chelates may be useful in facilitating de novo syntheses of essential metalloelement-dependent enzymes required to repair radiation injury. Reports of radioprotection, which involves treatment before irradiation, with calcium-channel blockers, acyl Melatonin homologs, and substituted anilines, which may serve as chelating agents after biochemical modification in vivo, as well as Curcumin, which is a chelating agent, have been included in this review. These inclusions are intended to suggest additional approaches to combination treatments that may be useful in facilitating radiation recovery. These approaches to radioprotection and radiorecovery offer promise in facilitating recovery from radiation-induced injury experienced by patients undergoing radiotherapy for neoplastic disease and by individuals who experience environmental, occupational, or accidental exposure to ultraviolet, x-ray, or ?-ray radiation. Since there are no existing treatments of radiation-injury intended to facilitate tissue repair, studies of essential metalloelement chelates and combinations of them, as well as combinations of them with existing organic radioprotectants, seem worthwhile. PMID:18475999

  18. Iron chelation and the ventilatory response to hypoxia.

    PubMed

    Pokorski, Mieczyslaw; Antosiewicz, Justyna; Di Giulio, Camillo; Lahiri, Sukhamay

    2009-01-01

    Chelation of iron in in vitro carotid body emulates the effects of hypoxia. The role iron plays in in vivo ventilatory responses is unclear. In the current study we addressed this issue by examining the effects of chronic iron chelation on the hypoxic ventilatory response in 9 conscious Wistar rats. Acute responses to 14 and 9% O(2)in N(2) were recorded in the same rat before and then after 7 and 14 days of continuous iron chelation. Iron chelation was carried out with ciclopirox olamine (CPX) in a dose of 20 mg/kg daily, i.p. Ventilation was recorded with whole body plethysmography. We found that the peak hypoxic ventilation (V(E) achieved during 14 and 9% hypoxia was lower by 239.6+/-55.4(SE) and 269.6.2+/-69.2 ml min(-1)kg(-1), respectively, in the rats treated with CPX for 7 days. The decreases were not intensified by a longer duration of iron chelation. CPX failed to alter hypoxic sensitivity, assessed from the gain of peak V(E) with increasing strength of the hypoxic stimulus. In conclusion, we believe we have shown that iron is operational in shaping the hypoxic ventilatory response, but is not liable to be the underlying determinant of the hypoxic chemoreflex. PMID:19536484

  19. Molecular nanotechnologies of gelatin-immobilization using macrocyclic metal chelates

    PubMed Central

    Mikhailov, Oleg V.

    2014-01-01

    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

  20. Inflammation induced by photocoagulation laser is minimized by copper chelators.

    PubMed

    Cui, Jing Z; Wang, Xue-Feng; Hsu, Lena; Matsubara, Joanne A

    2009-07-01

    The effect of trientine hydrochloride (TRIEN), a copper-selective chelating agent, on retinal inflammation induced by photocoagulation laser treatment was studied. Nine Long-Evans rats were treated with TRIEN (0.5 mmol/kg per day, intraperitoneal injection) for 9 days. On day 8, each animal underwent unilateral photocoagulation laser treatment with an argon dye laser. On day 9, animals were killed and the eyes processed for immunohistochemistry and light microscopy. In the TRIEN-treated group, retinal thickness and number of macrophages (ED-1) were both significantly lower than in the saline-treated, control group exposed to laser photocoagulation. The results support the hypothesis that selective copper chelation prior to laser treatment may inhibit ocular inflammation. The results suggest that pretreatment with a selective copper-chelating compound can minimize retinal inflammation secondary to laser photocoagulation treatment, which may improve overall outcome of photocoagulation treatment for diabetic retinopathy. PMID:18566852

  1. Polyvalent metal ion chelating agents for xanthan solutions

    SciTech Connect

    Miller, J.W.; Tate, B.E.

    1984-08-21

    A stable xanthan solution with superior filterability and subterranean injectivity characteristics comprises biopolymer and a chelating agent selected from aliphatic alpha-hydroxy acids having from about 2-7 carbon atoms; aliphatic and aromatic beta-keto compounds having from about 4-9 carbon atoms; or 2- and 4-pyrones having a hydroxyl group alpha to the carbonyl and having 5 or 6 carbon atoms; said chelating agent being present in an amount of at least about 1.0 ppm of the total solution. A method of enhancing oil recovery comprising employing as a mobility control solution in oil-bearing formations a mixture of xanthan biopolymer and a chelating agent is also disclosed.

  2. Inositol hexaphosphate: a potential chelating agent for uranium.

    PubMed

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

    2007-01-01

    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

  3. Iron chelation inhibits the development of pulmonary vascular remodeling.

    PubMed

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

    2012-11-01

    Reactive oxygen species (ROS) have been implicated in the pathogenesis of pulmonary hypertension. Because iron is an important regulator of ROS biology, this study examined the effects 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 the 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

  4. Gas and liquid chromatography of metal chelates of pentamethylene dithiocarbamate

    Microsoft Academic Search

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

    2002-01-01

    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.

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

    PubMed

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

    2014-01-01

    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

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Dube, R. K.

    2008-05-01

    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.

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

    MedlinePLUS

    ... a trained health professional. What did the chelation infusions contain? For TACT, the active, 10-component, chelation ... of normal saline and 1.2% dextrose. The infusions were prepared at a central pharmacy for the ...

  9. Investigation of transformation of ferrous phases in 6XXX alloys during homogenizing annealing

    NASA Astrophysics Data System (ADS)

    Bryantsev, P.; Samoshina, M.

    2012-02-01

    The only operation of heat treatment of 6XXX alloys before extrusion is homogenizing annealing. The presence of needle particles of ?-Al5FeSi in a billet for extrusion negatively affects the limit extrusion rate and surface quality of extruded products. Passage of the phase transformation of ferrous phases is the main limiting factor in the length of homogenizing annealing. In this work the method of quantitative phase transformation analysis is proposed for estimation the completeness of the homogenizing annealing.

  10. Structural Basis of the Ferrous Iron Specificity of the Yeast Ferroxidase, Fet3p †

    Microsoft Academic Search

    Christopher S. Stoj; Anthony J. Augustine; Lynn Zeigler; Edward I. Solomon; Daniel J. Kosman

    2006-01-01

    Fet3p is a multicopper oxidase (MCO) that functions together with the iron permease, Ftr1p, to support high-affinity Fe uptake in yeast. Fet3p is a ferroxidase that, like ceruloplasmin and hephaestin, couples the oxidation of 4 equiv of FeII to the reduction of O2 to 2H2O. The ferrous iron specificity of this subclass of MCO proteins has not been delineated by

  11. Removal of chlorine dioxide disinfection by-products by ferrous salts

    Microsoft Academic Search

    A Katz; N Narkis

    2001-01-01

    Chlorine dioxide when used as an effective disinfectant forms undesirable disinfection by-products, i.e. chlorite and chlorate ions. The aim of this research was to study the removal of these ions by ferrous ions in the presence or absence of oxygen. The efficiency of Fe+2 for ClO?2 and ClO?3 removal was followed by a determination of their initial and final concentrations,

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

    Microsoft Academic Search

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

    2004-01-01

    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

  13. Lactoferrin efficacy versus ferrous sulfate in curing iron deficiency and iron deficiency anemia in pregnant women

    Microsoft Academic Search

    Rosalba Paesano; Francesca Berlutti; Miriam Pietropaoli; Fabrizio Pantanella; Enrica Pacifici; William Goolsbee; Piera Valenti

    2010-01-01

    Iron deficiency (ID) and iron deficiency anemia (IDA) are the most common iron disorders throughout the world. ID and IDA,\\u000a particularly caused by increased iron requirements during pregnancy, represent a high risk for preterm delivery, fetal growth\\u000a retardation, low birth weight, and inferior neonatal health. Oral administration of ferrous sulfate to cure ID and IDA in\\u000a pregnancy often fails to

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

    SciTech Connect

    Not Available

    1994-09-01

    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.)

  15. Effect of ferrous ion on photo heterotrophic hydrogen production by Rhodobacter sphaeroides

    Microsoft Academic Search

    Heguang Zhu; Herbert H. P. Fang; Tong Zhang; Lee A. Beaudette

    2007-01-01

    The effect of ferrous ion (0–3.2mg\\/l) on photo heterotrophic hydrogen production was studied in batch culture using sodium lactate as substrate. The results showed that hydrogen production by Rhodobacter sphaeroides was significantly suppressed when Fe2+ was limited. Hydrogen production increased linearly with an increase in Fe2+ concentration in the range of 0–1.6mg\\/l; reaching a maximum at 2.4mg\\/l. When hydrogen production

  16. Stress corrosion cracking of several high strength ferrous and nickel alloys

    NASA Technical Reports Server (NTRS)

    Nelson, E. E.

    1971-01-01

    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.

  17. Ferrous intraocular foreign bodies retained in the posterior segment: management options and results

    Microsoft Academic Search

    Viktória Mester; Ferenc Kuhn

    1998-01-01

    Purpose: Analysis of traditional versus comprehensive management techniques for eyes with ferrous IOFBs in the posterior segment.\\u000a Patients and methods: Retrospective review of 30 eyes undergoing IOFB removal by EM and of 34 eyes managed by PPV techniques. Results: Vitreous hemorrhage occurred commonly (EM group: 40%, PPV group: 50%). Only in the EM group did the intervention cause iatrogenic\\u000a vitreous

  18. The characterisation of structural and antioxidant properties of isoflavone metal chelates

    Microsoft Academic Search

    Stephen Dowling; Fiona Regan; Helen Hughes

    2010-01-01

    Isoflavone metal chelates are of interest as isoflavones act as oestrogen mimics. Metal interactions may enhance isoflavones biological properties so understanding isoflavone metal chelation is important for the commercial application of isoflavones. This work aimed to determine if isoflavones, daidzein (4',7-dihydroxyisoflavone) and genistein (4',5,7-trihydroxyisoflavone) could chelate with metals as isoflavone chelates. Biochanin A (4'-methoxy-5,7-dihydroxyisoflavone) was also examined for it's ability

  19. New developments in the processing of the non ferrous metal fraction of car scrap

    SciTech Connect

    Dalmijn, W.L.; Houwelingen, J.A. van [Delft Univ. of Technology (Netherlands). Faculty of Mining and Petroleum Engineering

    1995-12-31

    The processing of scrap and scrap cars starts with size reduction by a hammermill, or shredder. After the liberation the magnetic fraction is removed. The remaining nonmagnetic fraction mixed with other materials is screened and each fraction is processed separately. The increased use of plastic has a negative effect on the recovery of metals and waste production. At Huron Valley, Belleville Michigan, USA, the non-ferrous fraction from 5 million obsolete cars per year, containing 200,000 tons of non-ferrous metal, is processed. Aluminium is recovered with a heavy medium separation process and concentrated with eddy current separators. The remaining heavy non-ferrous fraction is concentrated by a new combination of eddy current separation and image processing. After this separation process the zinc fraction is melted and refined and the copper, brass, stainless steel and other high-quality concentrates are sold to the secondary industries. The recycling of car scrap has become an important source of metals and materials for the secondary materials processing industry.

  20. Isolation and characterization of an acidophilic, heterotrophic bacterium capable of oxidizing ferrous iron.

    PubMed Central

    Johnson, D B; Ghauri, M A; Said, M F

    1992-01-01

    A heterotrophic bacterium, isolated from an acidic stream in a disused pyrite mine which contained copious growths of "acid streamers," displayed characteristics which differentiated it from previously described mesophilic acidophiles. The isolate was obligately acidophilic, with a pH range of 2.0 to 4.4 and an optimum pH of 3.0. The bacterium was unable to fix carbon dioxide but oxidized ferrous iron, although at a slower rate than either Thiobacillus ferrooxidans or Leptospirillum ferrooxidans. Elemental sulfur and manganese(II) were not oxidized. In liquid media, the isolate produced macroscopic streamerlike growths. Microscopic examination revealed that the bacterium formed long (greater than 100 microns) filaments which tended to disintegrate during later growth stages, producing single, motile cells and small filaments. The isolate did not appear to utilize the energy from ferrous iron oxidation. Both iron (ferrous or ferric) and an organic substrate were necessary to promote growth. The isolate displayed a lower tolerance to heavy metals than other iron-oxidizing acidophiles, and growth was inhibited by exposure to light. There was evidence of extracellular sheath production by the isolate. In this and some other respects, the isolate resembles members of the Sphaerotilus-Leptothrix group of filamentous bacteria. The guanine-plus-cytosine content of the isolate was 62 mol%, which is less than that recorded for Sphaerotilus-Leptothrix spp. and greater than those of L. ferrooxidans and most T. ferrooxidans isolates. Images PMID:1622207

  1. Stable intermediate-spin ferrous iron in lower-mantle perovskite

    SciTech Connect

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

    2008-11-10

    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.

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

    SciTech Connect

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

    2009-09-28

    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.

  3. Lactoferrin efficacy versus ferrous sulfate in curing iron deficiency and iron deficiency anemia in pregnant women.

    PubMed

    Paesano, Rosalba; Berlutti, Francesca; Pietropaoli, Miriam; Pantanella, Fabrizio; Pacifici, Enrica; Goolsbee, William; Valenti, Piera

    2010-06-01

    Iron deficiency (ID) and iron deficiency anemia (IDA) are the most common iron disorders throughout the world. ID and IDA, particularly caused by increased iron requirements during pregnancy, represent a high risk for preterm delivery, fetal growth retardation, low birth weight, and inferior neonatal health. Oral administration of ferrous sulfate to cure ID and IDA in pregnancy often fails to increase hematological parameters, causes adverse effects and increases inflammation. Recently, we have demonstrated safety and efficacy of oral administration of 30% iron saturated bovine lactoferrin (bLf) in pregnant women suffering from ID and IDA. Oral administration of bLf significantly increases the number of red blood cells, hemoglobin, total serum iron and serum ferritin already after 30 days of the treatment. The increasing of hematological values by bLf is related to the decrease of serum IL-6 and the increase of serum hepcidin, detected as prohepcidin, whereas ferrous sulfate increases IL-6 and fails to increase hematological parameters and prohepcidin. bLf is a more effective and safer alternative than ferrous sulfate for treating ID and IDA in pregnant women. PMID:20407805

  4. Iron and pH-responsive FtrABCD ferrous iron utilization system of Bordetella species

    PubMed Central

    Brickman, Timothy J.; Armstrong, Sandra K.

    2012-01-01

    Summary A putative operon encoding an uncharacterized ferrous iron transport (FtrABCD) system was previously identified in cDNA microarray studies. In growth studies using buffered medium at pH values ranging from pH 6.0 to 7.6, Bordetella pertussis and Bordetella bronchiseptica FtrABCD system mutants showed dramatic reductions in growth yields under iron-restricted conditions at pH 6.0, but had no growth defects at pH 7.6. Supplementation of culture medium with 2 mM ascorbate reductant was inhibitory to alcaligin siderophore-dependent growth at pH 7.6, but had a neglible effect on FtrABCD system-dependent iron assimilation at pH 6.0 consistent with its predicted specificity for ferrous iron. Unlike Bordetella siderophore-dependent and haem iron transport systems, and in agreement with its hypothesized role in transport of inorganic iron from periplasm to cytoplasm, FtrABCD system function did not require the TonB energy transduction complex. Gene fusion analysis revealed that ftrABCD promoter activity was maximal under iron-restricted growth conditions at acidic pH. The pH of human airway surface fluids ranges from pH 5.5 to 7.9, and the FtrABCD system may supply ferrous iron necessary for Bordetella growth in acidic host microenvironments in which siderophores are ineffective for iron retrieval. PMID:22924881

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

    SciTech Connect

    Sit, P H L.; Cococcioni, Matteo; Marzari, Nicola N.

    2007-09-01

    The research described in this product was performed in part in the Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory. 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 hexaaqua 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.

  6. Amine-and Ether-Chelated Aryllithium ReagentssStructure and Dynamics

    E-print Network

    Reich, Hans J.

    Amine- and Ether-Chelated Aryllithium ReagentssStructure and Dynamics Hans J. Reich,* Wayne S (2, 3) and 5-, 6-, and 7-ring chelating ether (4, 5, 6) ortho substituents have been examined, and the effects of solvent additives. The 5- and 6-ring ether chelates (4, 5) compete well with THF, but the 6

  7. EDTA Chelation Therapy, Without Added Vitamin C, Decreases Oxidative DNA Damage and Lipid Peroxidation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Chelation therapy is thought to not only remove contaminating metals, but also to decrease free radical production. However, in standard EDTA chelation therapy high doses of vitamin C with potential prooxidant effects are often added to the chelation solution. We demonstrated previously that the in...

  8. Regeneration of chelated iron liquid redox sulfur recovery sorbents. Topical report, March 1995

    Microsoft Academic Search

    DeBerry

    1995-01-01

    Chelated iron liquid redox processes promise economical removal of hydrogen sulfide from natural gas with recovery of solid sulfur. After reaction, the iron chelate must be regenerated with air. The rates and mechanisms of these regeneration reactions are important because chemical degradation of the chelating agent, which occurs during air regeneration, is a major problem. The objective of this project

  9. Heavy metal stabilization in municipal solid waste incineration flyash using heavy metal chelating agents

    Microsoft Academic Search

    Jiang Jianguo; Wang Jun; Xu Xin; Wang Wei; Deng Zhou; Zhang Yan

    2004-01-01

    Heavy metal chemical stabilization with synthesized heavy metal chelating agent was assessed for flyash from municipal solid waste incinerator. Flyash can contain heavy metals (e.g. Pb, Cd) which can leach. A new kind of heavy metal chelating agent showed more attractive competition than inorganic chemicals in stabilizing flyash. The synthesizing method of this kind of heavy metal chelating agent was

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

    PubMed Central

    Andersen, Ole; Aaseth, Jan

    2002-01-01

    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

  11. A rapid assay for evaluation of iron-chelating agents in rats

    Microsoft Academic Search

    M. J. Pippard; D. K. Johnson; C. A. Finch

    1981-01-01

    The animal assay of potential new iron-chelating agents is at present dependent on cumbersome and imprecise iron balance studies in hypertransfused rodents. We report the development of a radioisotope assay in intact rats based on the transient labeling by ferritin 59Fe of the main source of chelatable iron within hepatocytes. The isotope was maximally available to chelators during the first

  12. Sandstone Acidizing Using Chelating Agents and their Interaction with Clays 

    E-print Network

    George, Noble Thekkemelathethil 1987-

    2013-01-09

    . The substitution of seawater in place of deionized water for mixing purposes also led to an increased conductivity of the core implying GLDA is compatible with seawater. In the static solubility tests, chelates were mixed with HF acid at various concentrations...

  13. THE INTERACTION BETWEEN METALS AND CHELATING AGENTS IN MAMMALIAN SPERMATOZOA

    Microsoft Academic Search

    I. G. WHITE

    1956-01-01

    Several studies have been made on the bacteriostatic and fungicidal properties of oxine (8-hydroxyquinoline) and other chelating agents, and it has been suggested that they might act, in part at least, by depriving cells of essential trace metals (Albert, 1951; Martell & Calvin, 1952). In an attempt to determine the trace element requirements of mammalian spermatozoa, White (1955) investigated the

  14. Efficacy of reversal of aortic calcification by chelating agents

    PubMed Central

    Lei, Yang; Sinha, Aditi; Vyavahare, Naren

    2013-01-01

    Elastin specific medial vascular calcification, termed Monckeberg’s sclerosis has been recognized as a major risk factor for various cardiovascular events. We hypothesize that chelating agents, such as disodium ethylene diamine tetraacetic acid (EDTA), diethylene triamine pentaacetic acid (DTPA) and sodium thiosulfate (STS) might reverse elastin calcification by directly removing calcium (Ca) from calcified tissues into soluble calcium complexes. We assessed the chelating ability of EDTA, DTPA, and STS on removal of calcium from hydroxyapatite (HA) powder, calcified porcine aortic elastin, and calcified human aorta in vitro. We show that both EDTA and DTPA could effectively remove calcium from HA and calcified tissues, while STS was not effective. The tissue architecture was not altered during chelation. In the animal model of aortic elastin-specific calcification, we further show that local periadventitial delivery of EDTA loaded in to poly (lactic-co-glycolic acid) (PLGA) nanoparticles regressed elastin specific calcification in the aorta. Collectively, the data indicate that elastin-specific medial vascular calcification could be reversed by chelating agents. PMID:23963635

  15. Hydroxamate recognition during iron transport from hydroxamate-iron chelates

    Microsoft Academic Search

    A. H. Haydon; W. B. Davis; E. L. Arceneaux; B. R. Byers

    1973-01-01

    Kinetics of radioactive iron transport from three structurally different ; secondary hydroxandate-iron chelates (schizokineniron, produced by Bacillus ; megaterium ATCC 19213; Desferaliron, produced by an actinomycete; and aerobactin-; iron, produced by Aerobacter aerogenes 62-1) revealed that B. megateriurm SK 11 ; (a mutant that cannot synthesize schizokinen) has a specific transport system for ; utilization of ferric hydroxamates with a

  16. Aluminium and iron in the brain—prospects for chelation

    Microsoft Academic Search

    Robert R Crichton; Anne Florence; Roberta J Ward

    2002-01-01

    Aluminium and iron both accumulate in the brain in the course of ageing. We first briefly review how aluminium may interfere with iron metabolism through its interaction with iron homeostatic mechanisms. Then we present comparative data on the chelation of brain aluminium and iron in appropriate animal models of loading with the two metals. With both desferrioxamine (DFO) B and

  17. SWELLING OF A CHELATING MACROPOROUS RESIN DURING METAL ION EXCHANGE

    Microsoft Academic Search

    F. Mijangos; M. Ortueta; I. Aguirre

    2000-01-01

    The kinetics of heavy metal ion exchange onto a commercial chelating resin was investigated from the standpoint of the swelling-shrinking experienced by the resin bead during the overall ion exchange process. Temporal measurements of the volume variations were carried out for every step of an operational cycle, metal load, elution and regeneration of the ion exchanger, using a microreactor mainly

  18. Effect of iron chelation on inflammatory joint disease

    Microsoft Academic Search

    F J Andrews; C J Morris; G Kondratowicz; D R Blake

    1987-01-01

    Mild iron deficiency induced by treatment with the iron chelator desferrioxamine reduced the incidence and severity of joint inflammation associated with adjuvant disease in rats but did not alter the local primary inflammatory response or the systemic sequelae. Both rats treated with desferrioxamine and control rats showed increased levels of alpha 1 acid glycoprotein, characteristic pathological changes in the liver

  19. Chelation of thallium by combining deferasirox and desferrioxamine in rats.

    PubMed

    Shokooh Saljooghi, Amir; Babaie, Maryam; Delavar Mendi, Fatemeh; Zahmati, Maliheh; Shokooh Saljooghi, Zoheir

    2013-09-10

    The hypothesis that two known chelators deferasirox (4-[3,5-bis(2-hydroxyphenyl)-1,2,4-triazol-1-yl]-benzoic acid) and desferrioxamine (DFO) might be more efficient as combined treatment than as monotherapies in removing thallium from the body was tested in a new acute rat model. 7-week-old male Wistar rats received chelators: deferasirox (orally), DFO (intraperitoneal; i.p.), or deferasirox + DFO as 75 or 150 mg/kg dose half an hour after a single i.p. administration of 8 mg thallium/kg body weight in the form of chloride. Serum thallium concentration, urinary thallium, and iron excretions were determined by graphite furnace atomic absorption spectrometry. Both chelators were effective only at the higher dose level, while DFO was more effective than deferasirox in enhancing urinary thallium excretion, deferasirox was more effective than DFO in enhancing urinary iron excretion. In the combined treatment group, deferasirox did not increase the DFO effect on thallium and DFO did not increase the effect of deferasirox on iron elimination. Our results support the usefulness of this animal model for preliminary in vivo testing of thallium chelators. Urinary values were more useful because of the high variability of serum results. PMID:24021432

  20. Chelation of aluminum by combining deferasirox and deferiprone in rats.

    PubMed

    Saljooghi, Amir Shokooh

    2012-09-01

    The hypothesis that two known chelators deferasirox and deferiprone (L1) might be more efficient as combined treatment than as single therapies in removing aluminum from the body was tested in a new acute rat model. Seven-week-old male Wistar rats received chelators: deferasirox (orally [p.o.]), L1 (p.o.) or deferasirox + L1 as 100 or 200 mg/kg dose half an hour after a single intraperitoneal administration of 6 mg Al/kg body weight in the form of chloride. Serum aluminum concentration, urinary aluminum and iron excretions were determined by graphite furnace atomic absorption spectrometry. Both chelators were effective only at the higher dose level. While deferasirox was more effective than L1 in enhancing urinary aluminum excretion, L1 was more effective than deferasirox in enhancing urinary iron excretion. In the combined treatment group, deferasirox did not increase the L1 effect on aluminum and L1 did not increase the effect of deferasirox on iron elimination. Our results support the usefulness of this animal model for preliminary in vivo testing of aluminum chelators. Urinary values were more useful due to the high variability of serum results. PMID:22025507

  1. Comparison of 24-month outcomes in chelated and non-chelated lower-risk patients with myelodysplastic syndromes in a prospective registry.

    PubMed

    Lyons, Roger M; Marek, Billie J; Paley, Carole; Esposito, Jason; Garbo, Lawrence; DiBella, Nicholas; Garcia-Manero, Guillermo

    2014-02-01

    This 5-year, prospective registry enrolled 600 lower-risk MDS patients (pts) with transfusional iron overload. Clinical outcomes were compared between chelated and nonchelated pts. At baseline, cardiovascular comorbidities were more common in non-chelated pts, and MDS therapy was more common in chelated pts. At 24 months, chelation was associated with longer median overall survival (52.2 months vs. 104.4 months; p<.0001) and a trend toward longer leukemia-free survival and fewer cardiac events. No differences in safety were apparent between groups. Limitations of this analysis included, varying time from diagnosis and duration of chelation, and the fact that the decision to chelate may have been influenced by pt clinical status. PMID:24314590

  2. Iron chelation studies using desferrioxamine and the potential oral chelator, 1,2-dimethyl-3-hydroxypyrid-4-one, in normal and iron loaded rats.

    PubMed Central

    Kontoghiorghes, G J; Sheppard, L; Hoffbrand, A V; Charalambous, J; Tikerpae, J; Pippard, M J

    1987-01-01

    A novel iron chelator, 1,2-dimethyl-3-hydroxypyrid-4-one, and desferrioxamine were compared for their ability to remove iron and for their site of action in iron release in rats. Repeated intraperitoneal injections of the chelators in rats with widespread tissue labelling by 59Fe derived from transferrin showed comparable 59Fe mobilisation by each chelator in normal and iron loaded rats. Specific labelling of a chelatable "cold" iron pool in hepatocytes by 59Fe derived from ferritin showed this pool to be equally accessible to parenteral doses of both chelators and also to oral 1,2-dimethyl-3-hydroxypyrid-4-one, which is an effective oral iron chelating agent that removes iron from parenchymal cells. This and other alpha-ketohydroxypyridines need further development as potential therapeutic agents in human iron overload. PMID:3584483

  3. Iron chelation studies using desferrioxamine and the potential oral chelator, 1,2-dimethyl-3-hydroxypyrid-4-one, in normal and iron loaded rats

    Microsoft Academic Search

    G J Kontoghiorghes; L Sheppard; A V Hoffbrand; J Charalambous; J Tikerpae; M J Pippard

    1987-01-01

    A novel iron chelator, 1,2-dimethyl-3-hydroxypyrid-4-one, and desferrioxamine were compared for their ability to remove iron and for their site of action in iron release in rats. Repeated intraperitoneal injections of the chelators in rats with widespread tissue labelling by 59Fe derived from transferrin showed comparable 59Fe mobilisation by each chelator in normal and iron loaded rats. Specific labelling of a

  4. The proceedings of the 20th International Conference on Chelation held in the USA: advances on new and old chelation therapies.

    PubMed

    Kontoghiorghes, George J

    2013-01-01

    New developments on chelation have been discussed during the 20th International Conference on Chelation in Grand Rapids, MI, USA, which could affect the treatments of millions of patients worldwide. The complete treatment of transfusional iron overload in thalassaemia using the deferiprone (L1) and deferoxamine combination is a paradigm to be followed in the treatment of many other metal toxicity conditions. Encouraging results from clinical testing increased the prospects of the application of L1 as a pharmaceutical chelator antioxidant in renal, neurodegenerative and other conditions. The development of new chelators for the detoxification of heavy and radioactive metals is in the final stages of approval for clinical use. EDTA chelation for heavy metal detoxification has been used in millions of patients worldwide in the last 50 years and continues to attract many categories of patients because of low toxicity and therapeutic benefits. Major changes on chelation therapy policy have been introduced by the FDA in the USA in the last few years, including the approval of L1 in 2011, the release of reports with 2474 fatalities which include thalassaemia and sickle cell anaemia patients in the period 2007-2011 in the case of deferasirox and the reappraisal of EDTA chelation therapy by NIH for patients who have suffered myocardial infraction. Major controversies in the use of chelating drugs worldwide include the risk/benefit assessment of different chelation protocols for different conditions and the commercial conflicts between generic and patented drugs. PMID:22900514

  5. Fractionation and identification of Alaska pollock skin collagen-derived mineral chelating peptides.

    PubMed

    Guo, Lidong; Harnedy, Pádraigín A; O'Keeffe, Martina B; Zhang, Li; Li, Bafang; Hou, Hu; FitzGerald, Richard J

    2015-04-15

    Peptides with the ability to chelate dietary minerals have been reported to have potential as functional food ingredients. A collagen tryptic hydrolysate (CTH), previously shown to chelate iron, was further investigated for the presence of Ca, Fe and Cu chelating peptides. Sequential purification steps, including immobilised metal affinity chromatography (IMAC) and gel permeation chromatography (GPC) were employed for the separation of chelating peptides. GPC analysis showed that the mineral chelating peptides were mainly between 500 and 2000 Da. Subsequent identification was carried out using UPLC-ESI-QTOF MS/MS. Overall, 10 sequences were identified as potential chelating peptides. The Ca, Fe and Cu chelating activity of GPAGPHGPPG was 11.52±2.23 nmol/?mol, 1.71±0.17 nmol/?mol and 0.43±0.02 ?mol/?mol, respectively. This study identifies collagen as a good source of peptides with potential applications as functional ingredients in the management of mineral deficiencies. PMID:25466056

  6. Method of radioactively labeling diagnostic and therapeutic agents containing a chelating group

    SciTech Connect

    Stavrianopoulos, J.G.

    1987-11-17

    A method of forming a therapeutic or diagnostic agent labeled with a radioactive metal ion is described, which comprises: (A) contacting; (1) an unlabeled therapeutic or diagnostic agent comprising: (a) a molecularly recognizable portion attached to, (b) a chelating portion capable of substantially chelating with the radioactive metal ion, wherein the chelating portion is not a part of the molecularly recognizable portion, with (2) an ion transfer material having the radioactive metal ion bound thereto and having a binding affinity for the radioactive metal ion less than the binding affinity of the chelating portion for the radioactive metal ion. The chelating portion is unchelated or is chelated with a second metal having a binding affinity with the chelating portion less than the binding affinity of the radioactive metal ion, whereby a radiolabeled therapeutic or diagnostic agent is formed by the contacting; and (B) separating the radiolabeled therapeutic or diagnostic agent from the ion transfer material.

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

    PubMed Central

    2011-01-01

    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

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

    SciTech Connect

    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

    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.

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

    SciTech Connect

    Bates, C.E.; Griffin, J.; Giese, S.R.; Lane, A.M. [and others

    1996-01-31

    This is the final report covering work performed on research into methods of attaining clean ferrous castings. In this program methods were developed to minimize the formation of inclusions in steel castings by using a variety of techniques which decreased the tendency for inclusions to form during melting, casting and solidification. In a second project, a reaction chamber was built to remove inclusions from molten steel using electromagnetic force. Finally, a thorough investigation of the causes of sand penetration defects in iron castings was completed, and a program developed which predicts the probability of penetration formation and indicates methods for avoiding it.

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

    DOEpatents

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

    1981-01-01

    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.

  11. [Modification of MSWI fly ash by using anionic chelating surfactant].

    PubMed

    Zhang, Hou-Hu; Qian, Guang-Ren; Zhang, Xiao-Lan

    2005-07-01

    This paper aims at the reutilization and stabilization of municipal solid waste incineration (MSWI) fly ash to produce a high value added product. The effects of anionic chelating surfactants on the surface modification and fixing capacity of MSWI fly ash were primarily explored. Based on the indexes of active ratio and analysis of IR-spectrometer, the active ratio of ACS1 modified fly ash can be found higher than 95% under the condition of surfactant dosage at 7.0mL/100g fly ash, modification time at 15min and temperature at 75 degrees C . Moreover, Anionic chelating surfactant shows a strong fixing capacity for heavy metals by the United States Environmental Protection Agency's Toxicity Characteristic Leaching Procedure (TCLP). PMID:16212196

  12. Multidentate terephthalamidate and hydroxypyridonate ligands: towards new orally active chelators.

    PubMed

    Abergel, Rebecca J; Raymond, Kenneth N

    2011-01-01

    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 (59)Fe, (238)Pu, and (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. PMID:21599440

  13. A novel antimycobacterial compound acts as an intracellular iron chelator.

    PubMed

    Dragset, Marte S; Poce, Giovanna; Alfonso, Salvatore; Padilla-Benavides, Teresita; Ioerger, Thomas R; Kaneko, Takushi; Sacchettini, James C; Biava, Mariangela; Parish, Tanya; Argüello, José M; Steigedal, Magnus; Rubin, Eric J

    2015-04-01

    Efficient iron acquisition is crucial for the pathogenesis of Mycobacterium tuberculosis. Mycobacterial iron uptake and metabolism are therefore attractive targets for antitubercular drug development. Resistance mutations against a novel pyrazolopyrimidinone compound (PZP) that is active against M. tuberculosis have been identified within the gene cluster encoding the ESX-3 type VII secretion system. ESX-3 is required for mycobacterial iron acquisition through the mycobactin siderophore pathway, which could indicate that PZP restricts mycobacterial growth by targeting ESX-3 and thus iron uptake. Surprisingly, we show that ESX-3 is not the cellular target of the compound. We demonstrate that PZP indeed targets iron metabolism; however, we found that instead of inhibiting uptake of iron, PZP acts as an iron chelator, and we present evidence that the compound restricts mycobacterial growth by chelating intrabacterial iron. Thus, we have unraveled the unexpected mechanism of a novel antimycobacterial compound. PMID:25645825

  14. Pathophysiological and clinical aspects of iron chelation therapy in MDS.

    PubMed

    Gattermann, Norbert

    2012-01-01

    The majority of patients with myelodysplastic syndromes (MDS) become transfusion-dependent during the course of disease and may thus develop transfusional iron overload. As a further contributor to iron overload there is increased absorption of dietary iron from the gut, as a consequence of ineffective erythropoiesis. Compared with thalassemia, it is less clear how frequent patients with MDS develop clinical complications of iron overload, and whether the accumulation of iron shortens their survival. This review aims to summarize our current knowledge of the detrimental effects of transfusional iron overload in MDS, point out the risks associated with iron-induced oxidative stress, describe the tools available for diagnosing iron overload, indicate the treatment options with currently available iron chelators, and discuss the measurement of labile plasma iron (LPI) as a tool to monitor the efficacy of iron chelation therapy. PMID:22571702

  15. Improved paramagnetic chelate for molecular imaging with MRI

    NASA Astrophysics Data System (ADS)

    Winter, Patrick; Athey, Phillip; Kiefer, Garry; Gulyas, Gyongyi; Frank, Keith; Fuhrhop, Ralph; Robertson, David; Wickline, Samuel; Lanza, Gregory

    2005-05-01

    The relaxivity and transmetallation of two lipophilic paramagnetic chelates incorporated onto perfluorocarbon nanoparticles, i.e., gadolinium-methoxy-tetraazacyclododecane-tetraacetic acid phosphatidylethanolamine (Gd-MeO-DOTA-PE) and gadolinium-methoxy-tetraazacyclododecane-tetraacetic acid triglycine phosphatidylethanolamine (Gd-MeO-DOTA-triglycine-PE (Gd-MeO-DOTA-triglycine-PE)), were compared to a prototypic gadolinium-diethylene-triamine-pentaacetic acid bis-oleate (Gd-DTPA-BOA) paramagnetic formulation. Nanoparticles with MeO-DOTA-based chelates demonstrated higher relaxivity (40% higher for Gd-MeO-DOTA-PE and 55% higher for Gd-MeO-DOTA-triglycine-PE) and less transmetallation than the original Gd-DTPA-BOA-based agent.

  16. Neurodegenerative diseases and therapeutic strategies using iron chelators.

    PubMed

    Ward, Roberta J; Dexter, David T; Crichton, Robert R

    2015-07-01

    This review will summarise the current state of our knowledge concerning the involvement of iron in various neurological diseases and the potential of therapy with iron chelators to retard the progression of the disease. We first discuss briefly the role of metal ions in brain function before outlining the way by which transition metal ions, such as iron and copper, can initiate neurodegeneration through the generation of reactive oxygen and nitrogen species. This results in protein misfolding, amyloid production and formation of insoluble protein aggregates which are contained within inclusion bodies. This will activate microglia leading to neuroinflammation. Neuroinflammation plays an important role in the progression of the neurodegenerative diseases, with activated microglia releasing pro-inflammatory cytokines leading to cellular cell loss. The evidence for metal involvement in Parkinson's and Alzheimer's disease as well as Friedreich's ataxia and multiple sclerosis will be presented. Preliminary results from trials of iron chelation therapy in these neurodegenerative diseases will be reviewed. PMID:25716300

  17. MULTIDENTATE TEREPHTHALAMIDATE AND HYDROXYPYRIDONATE LIGANDS: TOWARDS NEW ORALLY ACTIVE CHELATORS

    SciTech Connect

    Abergel, Rebecca J.; Raymond, Kenneth N.

    2011-07-13

    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.

  18. Challenges Associated with Metal Chelation Therapy in Alzheimer's Disease

    PubMed Central

    Hegde, Muralidhar L.; Bharathi, P.; Suram, Anitha; Venugopal, Chitra; Jagannathan, Ramya; Poddar, Pankaj; Srinivas, Pullabhatla; Sambamurti, Kumar; Rao, Kosagisharaf Jagannatha; Scancar, Janez; Messori, Luigi; Zecca, Luigi; Zatta, Paolo

    2010-01-01

    A close association between brain metal dishomeostasis and the onset and/or progression of Alzheimer's disease (AD) has been clearly established in a number of studies, although the underlying biochemical mechanisms remain obscure. This observation renders chelation therapy an attractive pharmacological option for the treatment of this disease. However, a number of requirements must be fulfilled in order to adapt chelation therapy to AD so that the term “metal targeted strategies” seems now more appropriate. Indeed, brain metal redistribution rather than brain metal scavenging and removal is the major goal of this type of intervention. The most recent developments in metal targeted strategies for AD will be discussed using, as useful examples, clioquinol, curcumin, and epigallocatechin, and the future perspectives will also be outlined. PMID:19363258

  19. Iron overload and chelation therapy in myelodysplastic syndromes.

    PubMed

    Temraz, Sally; Santini, Valeria; Musallam, Khaled; Taher, Ali

    2014-07-01

    Iron overload remains a concern in MDS patients especially those requiring recurrent blood transfusions. The consequence of iron overload may be more relevant in patients with low and intermediate-1 risk MDS who may survive long enough to experience such manifestations. It is a matter of debate whether this overload has time to yield organ damage, but it is quite evident that cellular damage and DNA genotoxic effect are induced. Iron overload may play a critical role in exacerbating pre-existing morbidity or even unmask silent ones. Under these circumstances, iron chelation therapy could play an integral role in the management of these patients. This review entails an in depth analysis of iron overload in MDS patients; its pathophysiology, effect on survival, associated risks and diagnostic options. It also discusses management options in relation to chelation therapy used in MDS patients and the impact it has on survival, hematologic response and organ function. PMID:24529413

  20. Flue gas desulfurization/denitrification using metal-chelate additives

    DOEpatents

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

    1985-08-05

    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.

  1. Capillary gas chromatography of metal chelates of diethyl dithiocarbamates

    Microsoft Academic Search

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

    2002-01-01

    Summary  Capillary GC of metal chelates of diethyl dithiocarbamate (DDTC) was examined on a methylsilicone DB-1 column, (25 meter,\\u000a 0.2 mm. i.d) with a film thickness of 0.25 ?m. Elution was carried out at the initial column temperature of 180C and programmed\\u000a at 5C min?1 to 260C. Detection was by FID or ECD. Symmetrical peaks with base line separation were obtained

  2. Extraction of heavy metals from soils using biodegradable chelating agents.

    PubMed

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

    2004-02-01

    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

  3. Crystal-Field Splitting in Yb3+ Chelates

    Microsoft Academic Search

    W. G. Perkins; G. A. Crosby

    1965-01-01

    Optical absorption and emission spectra of trivalent ytterbium in various chelates are reported. The experimental energy levels of Yb3+ are compared with predictions of electrostatic crystal-field theory and of a contact model of ligand-field theory. Good agreement is found between theory and experiment for the electrostatic crystal-field calculation. Poorer agreement is obtained using the ligand-field contact model calculation. The crystal-field

  4. Chelate-Enhanced Phytoremediation of Soils Polluted with Heavy Metals

    Microsoft Academic Search

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

    2004-01-01

    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

  5. Iron chelators ICL670 and 311 inhibit HIV1 transcription

    Microsoft Academic Search

    Zufan Debebe; Tatyana Ammosova; Marina Jerebtsova; Joseph Kurantsin-Mills; Xiaomei Niu; Sharroya Charles; Des R. Richardson; Patricio E. Ray; Victor R. Gordeuk; Sergei Nekhai

    2007-01-01

    HIV-1 replication is induced by an excess of iron and iron chelation by desferrioxamine (DFO) inhibits viral replication by reducing proliferation of infected cells. Treatment of cells with DFO and 2-hydroxy-1-naphthylaldehyde isonicotinoyl hydrazone (311) inhibit expression of proteins that regulate cell-cycle progression, including cycle-dependent kinase 2 (CDK2). Our recent studies showed that CDK2 participates in HIV-1 transcription and viral replication

  6. Deferasirox: Oral, once daily iron chelator — an expert opinion

    Microsoft Academic Search

    M. B. Agarwal

    2010-01-01

    Iron overload is a serious and potentially fatal condition that results from multiple blood transfusions required over a long\\u000a period of time to treat certain types of anemias such as, that caused by ?-thalassemia, sickle cell disease and myelodysplastic\\u000a syndrome. Deferoxamine, which has been used since four decades as an iron chelator has limited efficacy due to its demanding\\u000a therapeutic

  7. Activation of rotavirus RNA polymerase by calcium chelation

    Microsoft Academic Search

    J. Cohen; J. Laporte; A. Charpilienne; R. Scherrer

    1979-01-01

    Summary Two types of particles were isolated during purification of rotavirus. Dense (D) particles have a density of 1.38 in CsCl and exhibit spontaneously a fully active endogenous transcriptase. Light (L) particles (density 1.36 in CsCl) need to be treated with chelating agents to show a polymerase activity. The activation process of L particles was studied under strictly controlled monovalent,

  8. EFFECT OF TEMPERATURE ON THE SORPTION OF CHELATED RADIONUCLIDES.

    USGS Publications Warehouse

    Maest, Ann S.; Crerar, David A.; Dillon, Edward C.; Trehu, Stephen M.; Rountree, Tamara N.

    1985-01-01

    Temperature effects in the near-field radioactive waste disposal environment can result in changes in the adsorptive capacity and character of the substrate and the chemistry of the reacting fluids. This work examines the effect of temperature on 1) the kinetics of radionuclide sorption onto clays from 25 degree -75 degree C and 2) the degradation and metal-binding ability of two organic complexing agents found in chelated radioactive wastes and natural groundwaters.

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

    NASA Astrophysics Data System (ADS)

    Mistry, Jigar Kishorkumar

    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.

  10. Hydroxyurea could be a good clinically relevant iron chelator.

    PubMed

    Italia, Khushnooma; Colah, Roshan; Ghosh, Kanjaksha

    2013-01-01

    Our previous study showed a reduction in serum ferritin of ?-thalassemia patients on hydroxyurea therapy. Here we aimed to evaluate the efficacy of hydroxyurea alone and in combination with most widely used iron chelators like deferiprone and deferasirox for reducing iron from experimentally iron overloaded mice. 70 BALB/c mice received intraperitonial injections of iron-sucrose. The mice were then divided into 8 groups and were orally given hydroxyurea, deferiprone or deferasirox alone and their combinations for 4 months. CBC, serum-ferritin, TBARS, sTfr and hepcidin were evaluated before and after iron overload and subsequently after 4 months of drug therapy. All animals were then killed. Iron staining of the heart and liver tissue was done using Perl's Prussian Blue stain. Dry weight of iron in the heart and liver was determined by atomic absorption spectrometry. Increased serum-ferritin, TBARS, hepcidin and dry weight of iron in the liver and heart showed a significant reduction in groups treated with iron chelators with maximum reduction in the group treated with a combination of deferiprone, deferasirox and hydroxyurea. Thus hydroxyurea proves its role in reducing iron from iron overloaded mice. The iron chelating effect of these drugs can also be increased if given in combination. PMID:24349400

  11. Hydroxyurea Could Be a Good Clinically Relevant Iron Chelator

    PubMed Central

    Italia, Khushnooma; Colah, Roshan; Ghosh, Kanjaksha

    2013-01-01

    Our previous study showed a reduction in serum ferritin of ?-thalassemia patients on hydroxyurea therapy. Here we aimed to evaluate the efficacy of hydroxyurea alone and in combination with most widely used iron chelators like deferiprone and deferasirox for reducing iron from experimentally iron overloaded mice. 70 BALB/c mice received intraperitonial injections of iron-sucrose. The mice were then divided into 8 groups and were orally given hydroxyurea, deferiprone or deferasirox alone and their combinations for 4 months. CBC, serum-ferritin, TBARS, sTfr and hepcidin were evaluated before and after iron overload and subsequently after 4 months of drug therapy. All animals were then killed. Iron staining of the heart and liver tissue was done using Perl’s Prussian Blue stain. Dry weight of iron in the heart and liver was determined by atomic absorption spectrometry. Increased serum-ferritin, TBARS, hepcidin and dry weight of iron in the liver and heart showed a significant reduction in groups treated with iron chelators with maximum reduction in the group treated with a combination of deferiprone, deferasirox and hydroxyurea. Thus hydroxyurea proves its role in reducing iron from iron overloaded mice. The iron chelating effect of these drugs can also be increased if given in combination. PMID:24349400

  12. Regeneration of the heart in diabetes by selective copper chelation.

    PubMed

    Cooper, Garth J S; Phillips, Anthony R J; Choong, Soon Y; Leonard, Bridget L; Crossman, David J; Brunton, Dianne H; Saafi, 'Etuate L; Dissanayake, Ajith M; Cowan, Brett R; Young, Alistair A; Occleshaw, Christopher J; Chan, Yih-Kai; Leahy, Fiona E; Keogh, Geraldine F; Gamble, Gregory D; Allen, Grant R; Pope, Adèle J; Boyd, Peter D W; Poppitt, Sally D; Borg, Thomas K; Doughty, Robert N; Baker, John R

    2004-09-01

    Heart disease is the major cause of death in diabetes, a disorder characterized by chronic hyperglycemia and cardiovascular complications. Although altered systemic regulation of transition metals in diabetes has been the subject of previous investigation, it is not known whether changed transition metal metabolism results in heart disease in common forms of diabetes and whether metal chelation can reverse the condition. We found that administration of the Cu-selective transition metal chelator trientine to rats with streptozotocin-induced diabetes caused increased urinary Cu excretion compared with matched controls. A Cu(II)-trientine complex was demonstrated in the urine of treated rats. In diabetic animals with established heart failure, we show here for the first time that 7 weeks of oral trientine therapy significantly alleviated heart failure without lowering blood glucose, substantially improved cardiomyocyte structure, and reversed elevations in left ventricular collagen and beta(1) integrin. Oral trientine treatment also caused elevated Cu excretion in humans with type 2 diabetes, in whom 6 months of treatment caused elevated left ventricular mass to decline significantly toward normal. These data implicate accumulation of elevated loosely bound Cu in the mechanism of cardiac damage in diabetes and support the use of selective Cu chelation in the treatment of this condition. PMID:15331567

  13. Modification of MSW fly ash by anionic chelating surfactant.

    PubMed

    Qian, Guangren; Zhang, Houhu; Zhang, Xiaolan; Chui, Peng-Cheong

    2005-05-20

    This paper elucidates a study on the re-utilization and stabilization of municipal solid waste (MSW) fly ash in producing a high value-added product by the surface modification of anionic chelating surfactant on the particles. After modification, MSW fly ash can be expected using as a filler of ultra-high molecular weight polymers. The effects of anionic chelating surfactants (ACS) on surface modification of MSW fly ash and fixing capacity for heavy metals were explored. Meanwhile, the interaction mechanism between surfactants and MSW fly ash was suggested. The results showed that anionic chelating surfactants can be used to effectively modify MSW fly ash particles and achieve a high active ratio. At the same time, they also exhibited a strong fixing capacity for heavy metals. Of the two modified MSW fly ash, ED3A-modified MSW fly ash has a much higher active ratio than MAP-modified MSW fly ash at over 95%, although its fixing capacity for heavy metals was a shade lower than MAP-modified MSW fly ash. PMID:15885429

  14. Mercury removal in utility wet scrubber using a chelating agent

    DOEpatents

    Amrhein, Gerald T. (Louisville, OH)

    2001-01-01

    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.

  15. Effectiveness of chelation therapy with time after acute uranium intoxication.

    PubMed

    Domingo, J L; Ortega, A; Llobet, J M; Corbella, J

    1990-01-01

    The effect of increasing the time interval between acute uranium exposure and chelation therapy was studied in male Swiss mice. Gallic acid, 4,5-dihydroxy-1,3- benzenedisulfonic acid (Tiron), diethylenetriaminepentaacetic acid (DTPA), and 5-aminosalicylic acid (5-AS) were administered ip at 0, 0.25, 1, 4, and 24 hr after sc injection of 10 mg/kg of uranyl acetate dihydrate. Chelating agents were given at doses equal to one-fourth of their respective LD50 values. Daily elimination of uranium into urine and feces was determined for 4 days after which time the mice were killed, and the concentration of uranium was measured in kidney, spleen, and bone. The excretion of uranium was especially rapid in the first 24 hr. Treatment with Tiron or gallic acid at 0, 0.25, or 1 hr after uranium exposure significantly increased the total excretion of the metal. In kidney and bone, only administration of Tiron at 0, 0.25, or 1 hr after uranium injection, or gallic acid at 1 hr after uranium exposure significantly reduced tissue uranium concentrations. Treatment at later times (4 to 24 hr) did not increase the total excretion of the metal and did not decrease the tissue uranium concentrations 4 days after uranyl acetate administration. The results show that the length of time before initiating chelation therapy for acute uranium intoxication greatly influences the effectiveness of this therapy. PMID:2307325

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

    PubMed

    Zanella, Sante Guido; Roberti di Sarsina, Paolo

    2013-01-01

    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

  17. Prevention by chelating agents of metal-induced developmental toxicity.

    PubMed

    Domingo, J L

    1995-01-01

    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

  18. Carboxylate-containing chelating agent interactions with amorphous chromium hydroxide: Adsorption and dissolution

    NASA Astrophysics Data System (ADS)

    Carbonaro, Richard F.; Gray, Benjamin N.; Whitehead, Charles F.; Stone, Alan T.

    2008-07-01

    Anthropogenic chelating agents and biological chelating agents produced by indigenous organisms may dissolve Cr III (hydr)oxides in soils and sediments. The resulting dissolved Cr III-chelating agent complexes are more readily transported through porous media, thereby spreading contamination. With this work, we examine chelating agent-assisted dissolution of amorphous chromium hydroxide (ACH) by the (amino)carboxylate chelating agents iminodiacetic acid (IDA), nitrilotriacetic acid (NTA), tricarballylic acid (TCA), citric acid (CIT), ethylenediaminetetraacetic acid (EDTA), trans-1,2-cyclohexanediaminetetraacetic acid (CDTA), and trimethylenediaminetetraacetic acid (TMDTA). The extent of chelating agent adsorption onto ACH increased quickly over the first few hours, and then increased more gradually until a constant extent was attained. The extent of chelating agent adsorption versus pH followed "ligand-like" behavior. All chelating agents with the exception of TCA and IDA effectively dissolved significant amounts of ACH within 10 days from pH 4.0 to 9.4. IDA dissolved ACH below pH 6.5 and above pH 7.5. Rates of ACH dissolution normalized to the extent of chelating agent adsorption were pH dependent. IDA, NTA, CIT, and CDTA exhibited an increase in normalized dissolution rate with decreasing pH. EDTA and TMDTA exhibited a maximum in normalized dissolution rate near pH 8.5. Use of acetic acid as a pH buffer in experiments decreased the extent of chelating agent adsorption for IDA, NTA, and CIT but increased normalized rates of chelating agent-assisted dissolution for all chelating agents except EDTA. The results from this study provide the necessary information to calculate the extents and time scales of ACH dissolution in the presence of (amino)carboxylate chelating agents.

  19. Ferrous Analysis.

    ERIC Educational Resources Information Center

    Straub, William A.

    1989-01-01

    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…

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

    NASA Astrophysics Data System (ADS)

    Borisov, Alexander; Behrens, Harald; Holtz, Francois

    2013-12-01

    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.

  1. Prospects for Ukrainian ferrous metals in the post-soviet period

    USGS Publications Warehouse

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

    1998-01-01

    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.

  2. Effects of copper, with and without ferrous sulfide, and antibiotics on the performance of pigs.

    PubMed

    Ribeiro de Lima, F; Stahly, T S; Cromwell, G L

    1981-02-01

    Three trials were conducted with 252 pigs to determine the effects of the dietary additions of Cu (250 ppm as copper sulfate), with and without sulfide (500 ppm as ferrous sulfide), and antibiotics (55 ppm chlortetracycline or 27.5 ppm virginiamycin) on the performance and liver Cu stores of growing-finishing pigs. Single additions of Cu, chlortetracycline or virginiamycin to a 16% protein, corn-soybean meal-based diet improved daily gains by 4.0, 4.2 and 3.4% and feed to gain ratios by .3, 2.9, and 1.3%, respectively, in comparison with those of pigs fed the control diet. The addition of ferrous sulfide to the high Cu diets reduced liver Cu stores from 278 to 21 ppm, a level approaching that of the control pigs, and increased the growth response to supplemental Cu by 4.0%. The inclusion of both Cu and an antibiotic in the diet in the in the absence or presence of sulfide resulted in daily gains in feed to gain ratios similar to those of pigs receiving a single antimicrobial agent. These data suggest that the growth-promoting effects of Cu and chlortetracycline or Cu and virginiamycin are not additive in the growing-finishing pig allowed to consume feed ad libitum. PMID:6792177

  3. Removal of chlorine dioxide disinfection by-products by ferrous salts.

    PubMed

    Katz, A; Narkis, N

    2001-01-01

    Chlorine dioxide when used as an effective disinfectant forms undesirable disinfection by-products, i.e. chlorite and chlorate ions. The aim of this research was to study the removal of these ions by ferrous ions in the presence or absence of oxygen. The efficiency of Fe+2 for ClO2- and ClO3- removal was followed by a determination of their initial and final concentrations, pH and delta Fe+2 consumed/delta ClO2- removed ratios. The optimal weight ratio of delta Fe+2 consumed/delta ClO2- removed for complete ClO2 removal was found to be close to the theoretical calculated value of 3.31. It was proved that ferrous salts can reduce chlorite ions to harmless Cl- ions. This method can be recommended as a part of ClO2 disinfection to ensure safe drinking water, with no harm to water consumers and to the environment. PMID:11257863

  4. Olfactory ferric and ferrous iron absorption in iron-deficient rats

    PubMed Central

    Ruvin Kumara, V. M.

    2012-01-01

    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

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

    PubMed

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

    2014-05-01

    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

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

    NASA Technical Reports Server (NTRS)

    Mauzerall, David C.

    1990-01-01

    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.

  7. Full-scale implementation of the sodium sulfide/ferrous sulfate treatment process. Final report, October 1987-March 1989

    SciTech Connect

    Beller, J.M.; Carpenter, G.S.; McAtee, R.E.; Pryfogle, P.A.; Suciu, D.F.

    1989-09-01

    In Phase I, jar and dynamic testing showed that the sodium sulfide/ferrous sulfate process was a viable method for reducing hexavalent chromium and removing heavy metals from the Tinker AFB industrial wastewater with a significant decrease in sludge production and treatment costs. In Phase II pilot-plant field verification studies were conducted to evaluate the chemical and physical parameters of the chromium reduction process, the precipitation and clarification process, and the activated sludge system. Sludge production was evaluated and compared to the sulfuric acid/sulfur dioxide/lime process. The impact of and procedure for change-over to the sodium sulfide/ferrous sulfate process were also investigated.

  8. An experimental study for enhancing the catalytic effects of various copper forms on the oxidation of ferrous iron.

    PubMed

    Babak, Manizhe Moradi Shahre; Goharrizi, Ataallah Soltani; Mirzaei, Mohammad; Roayaei, Emad

    2013-01-01

    In this research the catalytic effect of copper compounds (ionic, oxide and oxide nanopowder) on the oxidation of ferrous iron by aeration was studied experimentally. When copper exists in solution, the oxidation rate of iron(II) will increase. The experimental results showed that the oxidation rate increases with an increasing copper concentration. From the experimental data it can be determined that the copper oxide nanopowder is the most effective for the oxidation reaction among the used copper forms. Aeration is the most economical oxidation method when water exhibits a high ferrous iron concentration. PMID:23530309

  9. Approaching 'Kit-Type' Labelling with (68) Ga: The DATA Chelators.

    PubMed

    Seemann, Johanna; Waldron, Bradley P; Roesch, Frank; Parker, David

    2015-06-01

    The DATA chelators are a novel class of tri-anionic ligands based on 6-amino-1,4-diazepine-triacetic acid, which have been introduced recently for the chelation of (68) Ga. Compared with macrocyclic chelators based on the cyclen scaffold (i.e., DOTA, DO3A, and DO2A derivatives), DATA chelators undergo quantitative radiolabelling more rapidly and under milder conditions. In this study, a systematic evaluation of the labelling of four DATA chelators-DATA(M) , DATA(P) , DATA(Ph) , and DATA(PPh) -with (68) Ga is presented. The results highlight the extraordinary potential of this new class of chelators for application in molecular imaging using (68) Ga positron emission tomography (PET). PMID:25899500

  10. 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...

  11. Comparison of measures of lead exposure, dose, and chelatable lead burden after provocative chelation in organolead workers.

    PubMed Central

    Schwartz, B S; McGrail, M P; Stewart, W; Pluth, T

    1994-01-01

    OBJECTIVES--To describe 6 h urinary lead excretion (6 h PbU) after 1 g intravenous ethylene diamine tetraacetic acid (EDTA) in organolead manufacturing workers with mixed exposure to organic and inorganic lead; to determine the predictors of lead excretion (PbU); and to determine the extent to which internal lead stores and ongoing external exposure govern blood concentrations of lead (PbB). METHODS--A case series of 21 active workers were studied. Personal industrial hygiene data, grouped by 29 exposure zones, in combination with personal interviews about work location and times were used to derive several measures of recent and cumulative exposure to organic and inorganic lead. The average exposure intensities assigned to the 29 zones ranged from 4 to 119 micrograms/m3 (0.02-0.57 mumol/m3 as lead) for organic lead and from 1 to 56 micrograms/m3 (0.004-0.27 mumol/m3) for inorganic lead. RESULTS--After controlling for age, 6 h PbU was significantly and positively correlated with summary measures of PbB--for example, lifetime peak PbB, time weighted PbB--and zinc protoporphyrin concentrations--for example, lifetime peak zinc protoporphyrin, time weighted zinc protoporphyrin--but not with measures of estimated external exposure--for example, duration of exposure and cumulative exposure to inorganic or organic lead. Among workers with higher chelatable lead burdens (6 h PbU > or = 212.4 micrograms (1.03 mumol) divided at the median), there was no apparent relation between recent inorganic lead exposure and PbB at the time of chelation. Among workers with lower chelatable lead burdens (6 h PbU < 212.4 micrograms (1.03 mumol) however, there was a significant relation between exposure and effect between recent exposure to inorganic lead and PbBs. CONCLUSION--These findings are consistent with the concept of physiological dampening. The high chelatable lead burden, a source of internal exposure, dampens the effect of external exposure on PbBs. The data suggest that in organolead workers with high chelatable lead burdens, PbBs may be more influenced by internal lead stores than by variations in airborne exposure to organic and inorganic lead. PMID:8000491

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

    Microsoft Academic Search

    W Wendlandt

    1957-01-01

    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

  13. Metal chelates of N,N'-dihydroxyethyl-N,N'-ethylenediaminedisuccinic acid and selected metal ions 

    E-print Network

    Hampton, Joan Martiner

    1972-01-01

    . At high pH, Ni(II), Co(II) and especially Cu(II) appeared to form in- soluble hydroxo chelates. Iron ( III) appeared to form soluble hydroxo chelates at high pH when the ratio of metal to ligand was 1:l. The values obtained for the formation constants...'-ethylene- diaminedisuccinic acid and its mag- nesium, calcium, manganese and lead chelates. . . page 13 2 ~ Potentiometric equilibrium curves of NgN'-dihydroxyethyl-N ~ N'-ethylene diaminedisuccinic acid and its copper, nickel and iron (I I I) chelates...

  14. Correlation of molecular structure with fluorescence spectra in rare earth chelates. I.

    NASA Technical Reports Server (NTRS)

    Bjorklund, S.; Degnan, J.; Filipescu, N.; Mcavoy, N.

    1968-01-01

    Rare earth chelates fluorescence spectra correlation with molecular structure, analyzing emission spectrum internal Stark splitting of tetramethylammonium tetrakis /dibenzoylmethido/europate microcrystals

  15. Transfusional iron overload and iron chelation therapy in thalassemia major and sickle cell disease.

    PubMed

    Marsella, Maria; Borgna-Pignatti, Caterina

    2014-08-01

    Iron overload is an inevitable consequence of blood transfusions and is often accompanied by increased iron absorption from the gut. Chelation therapy is necessary to prevent the consequences of hemosiderosis. Three chelators, deferoxamine, deferiprone, and deferasirox, are presently available and a fourth is undergoing clinical trials. The efficacy of all 3 available chelators has been demonstrated. Also, many studies have shown the efficacy of the combination of deferoxamine plus deferiprone as an intensive treatment of severe iron overload. Alternating chelators can reduce adverse effects and improve compliance. Adherence to therapy is crucial for good results. PMID:25064709

  16. A randomised double-blind study comparing sodium feredetate with ferrous fumarate in anaemia in pregnancy.

    PubMed

    Sarkate, Pankaj; Patil, Amrapali; Parulekar, Shashank; Rege, N N; Samant, B D; Lokhande, Jaisen; Gupta, Ashwaria; Kulkarni, Kamlakar

    2007-05-01

    Iron deficiency anaemia is a major health problem in India especially in women of reproductive age group. The World Health Organisation recommends that the haemoglobin concentration should not fall below 11.0 g/dl at any time during pregnancy. The aim of study was to compare the efficacy and safety of two doses of sodium feredetate with ferrous fumarate in improving haemoglobin profile in pregnant anaemic women. Pregnant women with gestation period between 12 and 26 weeks having serum haemoglobin < 10 g/dl, serum ferritin levels less than 12 microg/l were included in the study. Patients were divided into 3 groups and drugs administered accordingly. A total of 48 patients were available for analysis which included 37 patients who had completed all the visits up to 75 days follow-up and 11 patients who were treatment failures. In group A combination of sodium feredetate (containing 33 mg of elemental iron) along with vitamin B12 (15 microg) and folic acid (1.5 mg) was administered twice a day. In group B combination of sodium feredetate (containing 66 mg of elemental iron) along with vitamin B12 (15 microg) and folic acid (1.5 mg) was administered twice a day. In group C combination of ferrous fumarate (containing 100 mg of elemental iron) along with vitamin B12 (15 microg) and folic acid (1.5 mg) was administered twice a day. Patients were evaluated for Hb, RBC count, MCV, MCH and MCHC at day 0, 30, 45, 60 and 75. Serum ferritin, serum iron, TIBC and transferrin saturation were assessed at recruitment and end study. Mean rise of haemoglobin at the completion of study, over that of basal values was 1.79 g/dl (0.71 to 2.87, 95% CI, p < 0.05) in group A, 1.84 g/dl (0.82 to 2.86, 95% CI, p < 0.05) in group B and 1.63 g/dl (0.38 to 2.88, 95% CI, p < 0.05) in group C. Safety assessment was done by doing liver and kidney function test at the time of recruitment and end study. Low doses of sodium feredetate (33 mg and 66 mg of elemental iron given twice daily) produce comparable results as higher dose of ferrous fumarate (100 mg elemental iron given twice daily). As there were no adverse effects reported with sodium feredetate, it can be concluded from this study that this new formulation appears to be effective in improving haemoglobin profile in pregnant anaemic women and is tolerated well. PMID:17915799

  17. Protonation of ferrous dinitrogen complexes containing a diphosphine ligand with a pendent amine.

    PubMed

    Heiden, Zachariah M; Chen, Shentan; Mock, Michael T; Dougherty, William G; Kassel, W Scott; Rousseau, Roger; Bullock, R Morris

    2013-04-01

    The addition of acids to ferrous dinitrogen complexes [FeX(N2)(P(Et)N(Me)P(Et))(dmpm)](+) (X = H, Cl, or Br; P(Et)N(Me)P(Et) = Et2PCH2N(Me)CH2PEt2; and dmpm = Me2PCH2PMe2) gives protonation at the pendent amine of the diphosphine ligand rather than at the dinitrogen ligand. This protonation increased the ?N2 band of the complex by 25 cm(-1) and shifted the Fe(II/I) couple by 0.33 V to a more positive potential. A similar IR shift and a slightly smaller shift of the Fe(II/I) couple (0.23 V) was observed for the related carbonyl complex [FeH(CO)(P(Et)N(Me)P(Et))(dmpm)](+). [FeH(P(Et)N(Me)P(Et))(dmpm)](+) was found to bind N2 about three times more strongly than NH3. Computational analysis showed that coordination of N2 to Fe(II) centers increases the basicity of N2 (vs free N2) by 13 and 20 pKa units for the trans halides and hydrides, respectively. Although the iron center increases the basicity of the bound N2 ligand, the coordinated N2 is not sufficiently basic to be protonated. In the case of ferrous dinitrogen complexes containing a pendent methylamine, the amine site was determined to be the most basic site by 30 pKa units compared to the N2 ligand. The chemical reduction of these ferrous dinitrogen complexes was performed in an attempt to increase the basicity of the N2 ligand enough to promote proton transfer from the pendent amine to the N2 ligand. Instead of isolating a reduced Fe(0)-N2 complex, the reduction resulted in isolation and characterization of HFe(Et2PC(H)N(Me)CH2PEt2)(P(Et)N(Me)P(Et)), the product of oxidative addition of the methylene C-H bond of the P(Et)N(Me)P(Et) ligand to Fe. PMID:23506204

  18. Inhibition of pitting in ferrous materials by carbonate as a function of temperature and alkalinity

    SciTech Connect

    Adamy, S.T.; Cala, F.R. [Church and Dwight Co., Inc., Princeton, NJ (United States)

    1999-09-01

    The ability of bicarbonate and carbonate salts to inhibit pitting in ferrous materials was studied in aerated alkaline solutions at 60 C. These conditions were used in order that the systems would be representative of typical aqueous metal cleaning systems. Even though ferrous materials generally have been regarded as exhibiting a low susceptibility to corrosion at pH values > 10, it was shown that for C4140 (UNS G41400), increasing the temperature to 60 C at pH 10 increased the overall corrosion rate (as measured by linear polarization) by about 20 times to 100 times compared with the rate at room temperature. Addition of potassium bicarbonate/potassium carbonate (KHCO{sub 3}/K{sub 2}CO{sub 3}) to the solution significantly reduced the corrosion rate. The influence of temperature at pH values of 11 to 13 on overall corrosion rate was very minor. To investigate the influence of alloy type, electrochemical experiments were performed at pH 11 at 60 C on gray cast iron type G-2 class 40 (UNS F12801), C4140 carbon steel, C1008 carbon steel (UNS G10080), and unalloyed iron. In cyclic polarization studies, pitting was observed in C4140 and in the cast iron solutions at pH 11 when only sodium hydroxide (NaOH) was present. Inclusion of KHCO{sub 3} and K{sub 2}CO{sub 3} inhibited the pitting. The threshold concentration to inhibit pitting in cast iron was 2 orders of magnitude higher than in the case of C4140. C1008 and iron showed no visible tendency to pit even when no carbonate was present. The tendency to exhibit localized corrosion was therefore more prevalent in materials with a higher amount of carbon, although scanning electron microscopy (SEM) indicated that features in the initial surfaces also may have contributed to relative corrosion susceptibilities. Analyses via x-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) indicated the probable presence of ferrous carbonate (FeCO{sub 3}) in the form of amorphous particulates on sample surfaces. Additional crystalline substances were found that were probably potassium and NaOH salts.

  19. Treatment of superficial siderosis with iron chelation therapy

    PubMed Central

    Cummins, Gemma; Crundwell, Gemma; Baguley, David; Lennox, Graham

    2013-01-01

    Superficial siderosis is caused by recurrent haemorrhage in the subarachnoid space leading to haemosiderin deposition. It typically causes the triad of ataxia, deafness and myelopathy. We report a patient who developed superficial siderosis following neurosurgery for syringomyelia and who had an improvement in his hearing and mobility following treatment with a new iron chelation therapy that can penetrate the blood–brain barrier. It provides an intriguing insight into a therapy that could potentially modify the course of this rare neurodegenerative disorder. Further studies are required to assess the clinical efficacy of deferiprone in superficial siderosis. PMID:23843408

  20. Treatment of superficial siderosis with iron chelation therapy.

    PubMed

    Cummins, Gemma; Crundwell, Gemma; Baguley, David; Lennox, Graham

    2013-01-01

    Superficial siderosis is caused by recurrent haemorrhage in the subarachnoid space leading to haemosiderin deposition. It typically causes the triad of ataxia, deafness and myelopathy. We report a patient who developed superficial siderosis following neurosurgery for syringomyelia and who had an improvement in his hearing and mobility following treatment with a new iron chelation therapy that can penetrate the blood-brain barrier. It provides an intriguing insight into a therapy that could potentially modify the course of this rare neurodegenerative disorder. Further studies are required to assess the clinical efficacy of deferiprone in superficial siderosis. PMID:23843408

  1. Iron-Chelating Therapy for Transfusional Iron Overload

    PubMed Central

    Brittenham, Gary M.

    2011-01-01

    A 16-year-old boy with sickle cell anemia undergoes routine screening with transcranial Doppler ultrasonography to assess the risk of stroke. This examination shows an abnormally elevated blood-flow velocity in the middle cerebral artery. The hemoglobin level is 7.2 g per deciliter, the reticulocyte count is 12.5%, and the fetal hemoglobin level is 8.0%. Long-term treatment with red-cell transfusion is initiated to prevent stroke. A hematologist recommends prophylactic iron-chelating therapy. PMID:21226580

  2. IMPROVEMENT OF MAGNETICALLY SEPARATED FERROUS CONCENTRATE BY SHREDDING: A PERFORMANCE TEST. TEST NO. 4.07, RECOVERY 1, NEW ORLEANS

    EPA Science Inventory

    This report describes a series of test runs in which ferrous product magnetically recovered from municipal waste was further shredded in a small (50 hp) hammermill to free attached or entrapped contaminant. A belt magnet was then used to separate metal from the liberated contamin...

  3. CHARACTERIZATION OF RESIDUAL STRESSES IN FERROUS COMPONENTS BY MAGNETIC ANISOTROPY MEASUREMENTS USING A HALL EFFECT SENSOR ARRAY PROBE

    Microsoft Academic Search

    C. C. H. Lo

    2011-01-01

    A new surface sensor probe comprising an angular array of Hall effect sensors has been developed for characterization of residual stresses in ferrous materials by means of stress-induced magnetic anisotropy measurements. The sensor probe applies a radially spreading ac magnetic field to a test sample, and detects stray fields in different directions simultaneously to determine the principal stress axes. In

  4. Characterization of Residual Stresses in Ferrous Components by Magnetic Anisotropy Measurements Using a Hall Effect Sensor Array Probe

    Microsoft Academic Search

    C. C. H. Lo

    2011-01-01

    A new surface sensor probe comprising an angular array of Hall effect sensors has been developed for characterization of residual stresses in ferrous materials by means of stress-induced magnetic anisotropy measurements. The sensor probe applies a radially spreading ac magnetic field to a test sample, and detects stray fields in different directions simultaneously to determine the principal stress axes. In

  5. Rotating biological contactor for biochemical ferrous iron oxidation in the treatment of coal mine drainage. Master's thesis

    Microsoft Academic Search

    Olem

    1975-01-01

    Pilot scale testing of the rotating biological contactor for the oxidation of ferrous iron in acid coal mine drainage has shown the process to be dependable, efficient, and economically comparable to purely chemical methods of iron oxidation. The 0.5 meter device consisted of four sets of plastic discs affixed to a centralized shaft. As the discs rotated half immersed in

  6. Formation and characterization of an all-ferrous Rieske cluster and stabilization of the [2Fe-2S]0

    E-print Network

    Ullmann, G. Matthias

    of coupled reactions at iron­sulfur clusters and of the factors that determine the relative stabilities of their different oxidation states are discussed. Iron­sulfur (FeS) clusters are essential to all forms of life /0 couple is 1.0 V below the [2Fe-2S]2 /1 couple. The two cluster-bound ferrous irons are both high

  7. Characterization of Water Coordination to Ferrous Nitrosyl Complexes with fac-N2O, cis-N2O2, and N2O3 Donor Ligands.

    PubMed

    McCracken, John; Cappillino, Patrick J; McNally, Joshua S; Krzyaniak, Matthew D; Howart, Michael; Tarves, Paul C; Caradonna, John P

    2015-07-01

    Electron paramagnetic resonance (EPR) experiments were done on a series of S = (3)/2 ferrous nitrosyl model complexes prepared with chelating ligands that mimic the 2-His-1-carboxylate facial triad iron binding motif of the mononuclear nonheme iron oxidases. These complexes formed a comparative family, {FeNO}(7)(N2Ox)(H2O)3-x with x = 1-3, where the labile coordination sites for the binding of NO and solvent water were fac for x = 1 and cis for x = 2. The continuous-wave EPR spectra of these three complexes were typical of high-spin S = (3)/2 transition-metal ions with resonances near g = 4 and 2. Orientation-selective hyperfine sublevel correlation (HYSCORE) spectra revealed cross peaks arising from the protons of coordinated water in a clean spectral window from g = 3.0 to 2.3. These cross peaks were absent for the {FeNO}(7)(N2O3) complex. HYSCORE spectra were analyzed using a straightforward model for defining the spin Hamiltonian parameters of bound water and showed that, for the {FeNO}(7)(N2O2)(H2O) complex, a single water conformer with an isotropic hyperfine coupling, Aiso = 0.0 ± 0.3 MHz, and a dipolar coupling of T = 4.8 ± 0.2 MHz could account for the data. For the {FeNO}(7)(N2O)(H2O)2 complex, the HYSCORE cross peaks assigned to coordinated water showed more frequency dispersion and were analyzed with discrete orientations and hyperfine couplings for the two water molecules that accounted for the observed orientation-selective contour shapes. The use of three-pulse electron spin echo envelope modulation (ESEEM) data to quantify the number of water ligands coordinated to the {FeNO}(7) centers was explored. For this aspect of the study, HYSCORE spectra were important for defining a spectral window where empirical integration of ESEEM spectra would be the most accurate. PMID:26090963

  8. Gold nanoparticles functionalised with fast water exchanging Gd3+ chelates: linker effects on the relaxivity.

    PubMed

    Ferreira, Miguel F; Gonçalves, Janaina; Mousavi, Bibimaryam; Prata, Maria I M; Rodrigues, Sérgio P J; Calle, Daniel; López-Larrubia, Pilar; Cerdan, Sebastian; Rodrigues, Tiago B; Ferreira, Paula M; Helm, Lothar; Martins, José A; Geraldes, Carlos F G C

    2015-03-01

    The relaxivity displayed by Gd(3+) chelates immobilized onto gold nanoparticles is the result of the complex interplay between the nanoparticle size, the water exchange rate and the chelate structure. In this work we study the effect of the length of ?-thioalkyl linkers, anchoring fast water exchanging Gd(3+) chelates onto gold nanoparticles, on the relaxivity of the immobilized chelates. Gold nanoparticles functionalized with Gd(3+) chelates of mercaptoundecanoyl and lipoyl amide conjugates of the DO3A-N-(?-amino)propionate chelator were prepared and studied as potential CA for MRI. High relaxivities per chelate, of the order of magnitude 28-38 mM(-1) s(-1) (30 MHz, 25 °C), were attained thanks to simultaneous optimization of the rotational correlation time and of the water exchange rate. Fast local rotational motions of the immobilized chelates around connecting linkers (internal flexibility) still limit the attainable relaxivity. The degree of internal flexibility of the immobilized chelates seems not to be correlated with the length of the connecting linkers. Biodistribution and MRI studies in mice suggest that the in vivo behavior of the gold nanoparticles was determined mainly by size. Small nanoparticles (HD = 3.9 nm) undergo fast renal clearance and avoidance of the RES organs while larger nanoparticles (HD = 4.8 nm) undergo predominantly hepatobiliary excretion. High relaxivities, allied to chelate and nanoparticle stability and fast renal clearance in vivo suggest that functionalized gold nanoparticles hold great potential for further investigation as MRI contrast agents. This study contributes to a better understanding of the effect of linker length on the relaxivity of gold nanoparticles functionalized with Gd(3+) complexes. It is a relevant contribution towards "design rules" for nanostructures functionalized with Gd(3+) chelates as Contrast Agents for MRI and multimodal imaging. PMID:25611006

  9. [Degradation of diuron by persulfate oxidation activated by EDTA-ferrous ion in aqueous system].

    PubMed

    Zhang, Jin-Feng; Yang, Xi; Zheng, Wei; Kong, Ling-Ren; Wang, Lian-Hong

    2008-05-01

    The method of diuron [3-(3,4-dichlorophenyl)-1, 1-dimethylurea] degradation by persulfate oxidation activated by EDTA-ferrous ion in aqueous system was conducted. Based on both of the degradation performance and the operating costs, optimal reaction condition was proposed. Operating at K2S2O8 initial concentration 2.0 mmol x L(-1), Fe(II) initial concentration 1.0 mmol x L(-1), EDTA initial concentration 0.5 mmol x L(-1), reaction time 300 min and pH = 7.0, about 67.6% of 0.1 mmol x L(1) diuron was degradation. Hydroxyl radicals and sulfate radicals produced in the system were determined by molecular probes (ethanol and tert-butanol) methods. The degradation products of diuron were identified with LC/MS methods and the degradation pathways of diuron were discussed. PMID:18624186

  10. Fast start-up of Anammox process with appropriate ferrous iron concentration.

    PubMed

    Bi, Zhen; Qiao, Sen; Zhou, Jiti; Tang, Xin; Zhang, Jie

    2014-10-01

    In this study, three upflow column reactors were compared for anaerobic ammonium oxidation (Anammox) process start-up time with different ferrous iron concentration in feeding. Continuous experiments indicated that the start-up time of Anammox process could be shortened from 70 to 58d in R2 (0.06mM Fe(2+)) and 50d in R3 (0.09mM Fe(2+)). The Anammox activity appeared after 16days operation in R3. Quantitative PCR (q-PCR) analysis demonstrated a significant increase in quantity of Anammox bacteria in R3 compared with the other two reactors during entire operation. At the Fe(II) concentration of 0.09mM, the heme c levels inside Anammox cell and hydrazine dehydrogenase (HDH) activity increased dramatically, which could be the trigger of fast Anammox start-up. PMID:25164343

  11. Iron metabolism in aerobes: managing ferric iron hydrolysis and ferrous iron autoxidation

    PubMed Central

    Kosman, Daniel J.

    2012-01-01

    Aerobes and anaerobes alike express a plethora of essential iron enzymes; in the resting state, the iron atom(s) in these proteins are in the ferrous state. For aerobes, ferric iron is the predominant environmental valence form which, given ferric iron’s aqueous chemistry, occurs as ‘rust’, insoluble, bio-inert polymeric ferric oxide that results from the hydrolysis of [Fe(H2O)6]3+. Mobilizing this iron requires bio-ferrireduction which in turn requires managing the rapid autoxidation of the resulting FeII which occurs at pH > 6. This review examines the aqueous redox chemistry of iron and the mechanisms evolved in aerobes to suppress the ‘rusting out’ of FeIII and the ROS-generating autoxidation of FeII so as to make this metal ion available as the most ubiquitous prosthetic group in metallobiology. PMID:23264695

  12. Lung epithelium injury biomarkers in workers exposed to sulphur dioxide in a non-ferrous smelter.

    PubMed

    Haddam, Nahida; Samira, Sekkal; Dumont, Xavier; Taleb, Abdesselem; Haufroid, Vincent; Lison, Dominique; Bernard, Alfred

    2009-08-01

    Serum Clara cell protein (CC16) and surfactant-associated protein D (SP-D) were measured in 161 workers exposed to sulphur dioxide (SO(2)) in a non-ferrous smelter. Seventy workers from a blanket manufacture served as referents. Exposure to SO(2) and tobacco smoking were associated with a decrease of CC16 and an increase of SP-D in serum. Tobacco smoking and exposure SO(2) interacted synergistically to decrease serum CC16 but not to increase serum SP-D. While further illustrating the potential of serum CC16 and SP-D, our study confirms that SO(2) can cause airways damage at exposure levels below current occupational exposure limits. PMID:19552616

  13. Assessment of ferrous chloride and Portland cement for the remediation of chromite ore processing residue.

    PubMed

    Jagupilla, Santhi C; Wazne, Mahmoud; Moon, Deok Hyun

    2015-10-01

    Chromite Ore Processing Residue (COPR) is an industrial waste containing up to 7% chromium (Cr) including up to 5% hexavalent chromium [Cr(VI)]. The remediation of COPR has been challenging due to the slow release of Cr(VI) from a clinker like material and thereby the incomplete detoxification of Cr(VI) by chemical reagents. The use of sulfur based reagents such as ferrous sulfate and calcium polysulfide to detoxify Cr(VI) has exasperated the swell potential of COPR upon treatment. This study investigated the use of ferrous chloride alone and in combination with Portland cement to address the detoxification of Cr(VI) in COPR and the potential swell of COPR. Chromium regulatory tests, X-ray powder diffraction (XRPD) analyses and X-ray absorption near edge structure (XANES) analyses were used to assess the treatment results. The treatment results indicated that Cr(VI) concentrations for the acid pretreated micronized COPR as measured by XANES analyses were below the New Jersey Department of Environmental Protection (NJDEP) standard of 20mgkg(-1). The Toxicity characteristic leaching procedure (TCLP) Cr concentrations for all acid pretreated samples also were reduced below the TCLP regulatory limit of 5mgL(-1). Moreover, the TCLP Cr concentration for the acid pretreated COPR with particle size ?0.010mm were less than the universal treatment standard (UTS) of 0.6mgL(-1). The treatment appears to have destabilized all COPR potential swell causing minerals. The unconfined compressive strength (UCS) for the treated samples increased significantly upon treatment with Portland cement. PMID:25966327

  14. New concepts of iron and aluminium chelation therapy with oral L1 (deferiprone) and other chelators. A review.

    PubMed

    Kontoghiorghes, G J

    1995-03-01

    The introduction of oral chelation therapy with the alpha-ketohydroxypyridine chelator 1,2-dimethyl-3-hydroxypyrid-4-one (L1, INN/BAN: deferiprone) in iron- and aluminium-overloaded patients has been initiated in over 15 countries in the last 7 years. Over 600 patients with various conditions, in 26 centres have received L1, in some cases daily for over 5 years. In the vast majority of iron-loaded patients, doses of 55-100 mg kg-1 of L1 resulted in urinary iron excretion levels greater than those accumulating from transfusions (15-35 mg d-1) and also reduction in serum ferritin and liver iron to near normal levels. Urinary iron excretion was related to the iron load of the patients, as well as the dose and frequency of administration of L1. The L1 appears to mobilize iron mainly from a serum iron pool in excess of transferrin saturation, transferrin-bound iron and tissue iron, mainly but not exclusively from the liver. The order of metal binding by L1 at pH 7.4 is Fe > Cu > A1 > Zn. Aluminium removal from aluminium-loaded renal dialysis patients by L1 was also effective at doses similar to those used for iron-loaded patients. Overall toxic side effects include six cases of reversible agranulocytosis, 0-30% incidence of transient musculoskeletal and joint pains, 0-6% of gastric intolerance and 0-2% zinc deficiency. Deferiprone appears to be as effective as desferrioxamine in iron and aluminium removal and has low toxicity. Its oral efficacy and low cost make it more accessible than desferrioxamine for the vast majority of patients needing iron chelation worldwide. The development of other alpha-ketohydroxypyridines is currently in progress. PMID:7741239

  15. Ferrous Sulfate Supplementation Causes Significant Gastrointestinal Side-Effects in Adults: A Systematic Review and Meta-Analysis

    PubMed Central

    Tolkien, Zoe; Stecher, Lynne; Mander, Adrian P.; Pereira, Dora I. A.; Powell, Jonathan J.

    2015-01-01

    Background The tolerability of oral iron supplementation for the treatment of iron deficiency anemia is disputed. Objective Our aim was to quantify the odds of GI side-effects in adults related to current gold standard oral iron therapy, namely ferrous sulfate. Methods Systematic review and meta-analysis of randomized controlled trials (RCTs) evaluating GI side-effects that included ferrous sulfate and a comparator that was either placebo or intravenous (IV) iron. Random effects meta-analysis modelling was undertaken and study heterogeneity was summarised using I2 statistics. Results Forty three trials comprising 6831 adult participants were included. Twenty trials (n = 3168) had a placebo arm and twenty three trials (n = 3663) had an active comparator arm of IV iron. Ferrous sulfate supplementation significantly increased risk of GI side-effects versus placebo with an odds ratio (OR) of 2.32 [95% CI 1.74–3.08, p<0.0001, I2 = 53.6%] and versus IV iron with an OR of 3.05 [95% CI 2.07-4.48, p<0.0001, I2 = 41.6%]. Subgroup analysis in IBD patients showed a similar effect versus IV iron (OR = 3.14, 95% CI 1.34-7.36, p = 0.008, I2 = 0%). Likewise, subgroup analysis of pooled data from 7 RCTs in pregnant women (n = 1028) showed a statistically significant increased risk of GI side-effects for ferrous sulfate although there was marked heterogeneity in the data (OR = 3.33, 95% CI 1.19-9.28, p = 0.02, I2 = 66.1%). Meta-regression did not provide significant evidence of an association between the study OR and the iron dose. Conclusions Our meta-analysis confirms that ferrous sulfate is associated with a significant increase in gastrointestinal-specific side-effects but does not find a relationship with dose. PMID:25700159

  16. Multivalent chelators for spatially and temporally controlled protein functionalization.

    PubMed

    You, Changjiang; Piehler, Jacob

    2014-05-01

    Site-specific protein modification-e.g. for immobilization or labelling-is a key prerequisite for numerous bioanalytical applications. Although modification by use of short peptide tags is particularly attractive, efficient and bio-orthogonal systems are still lacking. Here, we review the application of multivalent chelators (MCH) for high-affinity yet reversible recognition of oligohistidine (His)-tagged proteins. MCH are based on multiple nitrilotriacetic acid (NTA) moieties grafted on to molecular scaffolds suitable for conjugation to surfaces, probes or other biomolecules. Reversible interaction with the His-tag is mediated via transition metal ions chelated by the NTA moieties. The small size and biochemical compatibility of these recognition units and the possibility of rapid dissociation of the interaction with His-tagged proteins despite sub-nanomolar binding affinity, enable distinct and versatile handling and modification of recombinant proteins. In this review, we briefly introduce the key principles and features of MCH-His-tag interactions and recapitulate the broad spectrum of bioanalytical applications with a focus on quantitative protein interaction analysis on micro or nano-patterned solid surfaces and specific protein labelling in living cells. PMID:24770786

  17. Chelating polymeric beads as potential therapeutics for Wilson's disease.

    PubMed

    Mattová, Jana; Pou?ková, Pavla; Ku?ka, Jan; Skodová, Michaela; Vetrík, Miroslav; St?pánek, Petr; Urbánek, Petr; Pet?ík, Miloš; Nový, Zbyn?k; Hrubý, Martin

    2014-10-01

    Wilson's disease is a genetic disorder caused by a malfunction of ATPase 7B that leads to high accumulation of copper in the organism and consequent toxic effects. We propose a gentle therapy to eliminate the excessive copper content with oral administration of insoluble non-resorbable polymer sorbents containing selective chelating groups for copper(II). Polymeric beads with the chelating agents triethylenetetramine, N,N-di(2-pyridylmethyl)amine, and 8-hydroxyquinoline (8HQB) were investigated. In a preliminary copper uptake experiment, we found that 8HQB significantly reduced copper uptake (using copper-64 as a radiotracer) after oral administration in Wistar rats. Furthermore, we measured organ radioactivity in rats to demonstrate that 8HQB radiolabelled with iodine-125 is not absorbed from the gastrointestinal tract after oral administration. Non-resorbability and the blockade of copper uptake were also confirmed with small animal imaging (PET/CT) in mice. In a long-term experiment with Wistar rats fed a diet containing the polymers, we have found that there were no signs of polymer toxicity and the addition of polymers to the diet led to a significant reduction in the copper contents in the kidneys, brains, and livers of the rats. We have shown that polymers containing specific ligands could potentially be novel therapeutics for Wilson's disease. PMID:24815561

  18. Fluorinated Paramagnetic Chelates as Potential Multi-chromic 19F Tracer Agents

    PubMed Central

    Jiang, Zhong-Xing; Feng, Yue

    2012-01-01

    A class of potential multi-chromic 19F imaging tracers is made by pairing metal ions with a fluorinated chelator. All fluorinated metal chelates emit a single 19F signal. Paramagnetic metal ions shifted the 19F signal frequency and made the 19F relaxation rates insensitive toward local chemical environment. PMID:21617807

  19. In vitro growth inhibition of bloodstream forms of Trypanosoma brucei and Trypanosoma congolense by iron chelators

    Microsoft Academic Search

    Karin Merschjohann; Dietmar Steverding

    2006-01-01

    African trypanosomes exert significant morbidity and mortality in man and livestock. Only a few drugs are available for the treatment of trypanosome infections and therefore, the development of new anti-trypanosomal agents is required. Previously it has been shown that bloodstream-form trypanosomes are sensitive to the iron chelator deferoxamine. In this study the effect of 13 iron chelators on the growth

  20. A rapid assay for evaluation of iron-chelating agents in rats

    SciTech Connect

    Pippard, M.J.; Johnson, D.K.; Finch, C.A.

    1981-10-01

    The animal assay of potential new iron-chelating agents is at present dependent on cumbersome and imprecise iron balance studies in hypertransfused rodents. We report the development of a radioisotope assay in intact rats based on the transient labeling by ferritin 59Fe of the main source of chelatable iron within hepatocytes. The isotope was maximally available to chelators during the first 6 hr after its injection, nearly all the excretion being in the bile. The bile 59Fe/total iron ratio was independent of both the chelator and its dose. However, in iron-loaded rats, the ratio was reduced, and the isotope excretion was a less sensitive measure of intrahepatic chelation. In the proposed assay, test chelators were given to normal rats 2 hr after an intravenous injection of 59Fe-ferritin. Four hours later, the radioiron in the liver and in the gut gave a sensitive measure of the mobilization of hepatic iron to the bile. In addition, chemical iron determinations identified a small alternative source of urinary chelate with agents known to promote urine excretion in man. The assay gave a rapid and precise screen for chelators given by parenteral and oral routes.

  1. Inhibitory activity of chelating agent against bacteria associated with poultry processing

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ethylenediaminetetraacetic acid (EDTA) and ethylenediamine-N, N’-disuccinic acid (EDDS) are chelating agents that can bind minerals that produce water hardness. By sequestering minerals in hard water, chelators reduce water hardness and increase the ability of cleansers to remove dirt and debris dur...

  2. Chelate formation of metals with hydroxytriphenylmethane dyes and its analytical applications

    Microsoft Academic Search

    Arun K. Dey

    1964-01-01

    Summary The formation of metal chelates of two hydroxytriphenylmethane dyes,viz., aurintricarboxylic acid (Aluminon, AAC) and sulphodichlorohydroxydimethylfuchson dicarboxylic acid (Chrome Azurol S, CAS) has been reviewed. The former forms coloured water soluble chelates with beryllium(II), aluminium(III), copper(II), iron(III), scandium(III), yttrium(III), rare earths, platinum metals, thorium(IV) and uranium(VI).

  3. Original Contribution Iron chelators can protect against oxidative stress through ferryl heme reduction

    Microsoft Academic Search

    Brandon J. Reeder; Robert C. Hider; Michael T. Wilson

    Iron chelators such as desferrioxamine have been shown to ameliorate oxidative damage in vivo. The mechanism of this therapeutic action under non-iron-overload conditions is, however, complex, as desferrioxamine has properties that can impact on oxidative damage independent of its capacity to act as an iron chelator. Desferrioxamine can act as a reducing agent to remove cytotoxic ferryl myoglobin and hemoglobin

  4. Chelators controlling metal metabolism and toxicity pathways: applications in cancer prevention, diagnosis and treatment.

    PubMed

    Kontoghiorghes, George J; Efstathiou, Aglaia; Ioannou-Loucaides, Stella; Kolnagou, Annita

    2008-01-01

    Chelating drugs and chelator metal complexes are used for the prevention, diagnosis and treatment of cancer. Cancer cells and normal cells require essential metal ions such as iron, copper and zinc for growth and proliferation. Chelators can target the metabolic pathways of cancer cells through the control of proteins involved in the regulation of these metals and also of other molecules involved in cell cycle control, angiogenesis and metastatic suppression. Other targets include the inhibition of specific proteins such as ribonucleotide reductase involved in DNA synthesis, the inhibition of free radical damage on DNA caused by iron and copper catalytic centers, the inhibition of microbial growth in immuno compromised cancer patients and the decorporation of radioactive and other toxic metals causing cancer. Chelating drugs and metal ions can affect the metabolism, efficacy and toxicity of anti-cancer drugs such as doxorubicin, mitozantrone, bleiomycin and hydroxyurea (HU). Although many experimental chelators have been shown to be effective as anti-cancer agents, only a few, e.g., dexrazoxane, deferoxamine (DFO) and triapine, have reached the stage of clinical testing or application. In many experimental models, deferiprone (L1) has been shown to be effective in cancer prevention and treatment, and in the inhibition of doxorubicin-induced cardiotoxicity. New anti-cancer drugs could be developed using chelators and chelator complexes with platinum and other metals, and also new protocols of combinations of chelators with known anti-cancer drugs. PMID:18274999

  5. Uptake and intracellular distribution of iron from transferrin and chelators in erythroid cells

    Microsoft Academic Search

    George J. Kontoghiorghes; Alison May

    1990-01-01

    Summary Iron chelators of different physicochemical properties were studied for their ability to donate iron in vitro to uninduced K562 cells, human bone marrow cells and purified human erythroblasts. To a large extent uptake was found to be related to lipophilicity and those chelators able to deliver iron to the cells in significant amounts were also able to deliver iron

  6. Covalent attachment of metal chelates to proteins:the stability in vivo and in vitro of the conjugate of albumin with a chelate of 111indium.

    PubMed Central

    Meares, C F; Goodwin, D A; Leung, C S; Girgis, A Y; Silvester, D J; Nunn, A D; Lavender, P J

    1976-01-01

    Human serum albumin has been conjugated to 1-(p-bnezenediazonium)-(ethylenedinitrilo)tetraacetic acid, a powerful chelating agent, and radioactive 111indium ions have been added specifically to the chelating groups. The product, with a specific radioactivity of about 1 mCi/mg of protein, was employed as a radiotracer in scintillation scanning studies with human volunteers. Results show that 48 hr after injection, practically all of the label remains attached to albumin. This is confirmed by electrophoresis of serum proteins; 7 days after injection, 85% of the radioactivity in the serum is still in the albumin fraction. These observations agree with in vitro studies of the labeled albumin in human serum, where loss of the metal ion from the chelating group to the protein transferrin amounts to less than 3% after 1 week and less than 5% after 2 weeks. Measurements of the distribution of label in mice up to 23 days after injection suggest that metabolism of the labeled protein does not lead to binding of indium ions by transferrin. The binding of indium and other metal ions by transferrin has previously posed a major impediment to the use of metal chelates for in vivo diagnostic procedures. Demonstration of the kinetic inertness of the chelate in these experiments suggests the use of related chelates as physical probes of biological systems. Images PMID:825856

  7. Chelation of hypocrellin B with zinc ions with electron paramagnetic resonance (EPR) evidence of the photodynamic activity of the resulting chelate.

    PubMed

    Tian, C; Xu, S; Chen, S; Shen, J; Zhang, M; Shen, T

    2001-11-01

    Hypocrellin B (HB), a perylenequinone derivative, is an efficient phototherapeutic agent. The chelation of HB with Zinc ions (Zn2+) results in a metal chelate (Zn-HB) which exhibits considerable absorption (lambda max = 612 nm) in the phototherapeutic window. The structure of this chelate has been characterized by UV-Vis, IR and mass spectra. The redox potentials of the Zn-HB chelate were Eox = +1.1 V (vs. SCE) and Ere = -0.7 V (vs. SCE) as measured using the circle volt curve. The quantum yield of singlet oxygen generated by the Zn-HB chelate was 0.86, which both the electron spin trap (EPR) method and the chemical trap method show to be about 0.1 higher than that of its parent compound HB. In irradiated oxygen-saturated solutions of Zn-HB chelate, superoxide radical anions and hydroxyl radicals were detected by EPR spectroscopy using 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) as the spin-trapping agent. PMID:11767412

  8. Convection-aided collection of metal ions using chelating porous flat-sheet membranes.

    PubMed

    Saito, Kaori; Saito, Kyoichi; Sugita, Kazuyuki; Tamada, Masao; Sugo, Takanobu

    2002-04-19

    Chelating porous membranes were prepared by radiation-induced graft polymerization of an epoxy-group-containing monomer onto a polyethylene flat sheet and subsequent conversion of the epoxy group to an iminodiacetate group as a chelate-forming group. The chelating group density on the resultant porous flat-sheet membrane of 1.0 mol/kg was comparable to that of commercially available chelating beads. The pure water permeability of the membrane was 40% that of the trunk porous membrane, which was used for microfiltration. During the permeation of a copper chloride solution through the membrane, diffusional mass-transfer resistance of copper ion was negligible, since the ion was transported by convective flow through the pore. The tensile strength and elongation at break of the membranes were measured as a function of dose of electron-beam irradiation, the degree of grafting, and the chelating group density to determine an applicable range for practical use. PMID:12058912

  9. Method for separating metal chelates from other materials based on solubilities in supercritical fluids

    DOEpatents

    Wai, Chien M. (Moscow, ID); Smart, Neil G. (Workington, GB); Phelps, Cindy (Moscow, ID)

    2001-01-01

    A method for separating a desired metal or metalloi from impurities using a supercritical extraction process based on solubility differences between the components, as well as the ability to vary the solvent power of the supercritical fluid, is described. The use of adduct-forming agents, such as phosphorous-containing ligands, to separate metal or metalloid chelates in such processes is further disclosed. In preferred embodiments, the extraction solvent is supercritical carbon dioxide and the chelating agent is selected from the group consisting of .beta.-diketones; phosphine oxides, such as trialkylphosphine oxides, triarylphosphine oxides and alkylarylphosphine oxides; phosphinic acids; carboxylic acids; phosphates, such as trialkylphosphates, triarylphosphates and alkylarylphosphates; crown ethers; dithiocarbamates; phosphine sulfides; phosphorothioic acids; thiophosphinic acids; halogenated analogs of these chelating agents; and mixtures of these chelating agents. In especially preferred embodiments, at least one of the chelating agents is fluorinated.

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

    PubMed

    Merkel, Drorit G; Nagler, Arnon

    2014-07-01

    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

  11. Regeneration of chelated iron liquid redox sulfur recovery sorbents. Topical report, March 1995

    SciTech Connect

    DeBerry, D.W.

    1995-03-01

    Chelated iron liquid redox processes promise economical removal of hydrogen sulfide from natural gas with recovery of solid sulfur. After reaction, the iron chelate must be regenerated with air. The rates and mechanisms of these regeneration reactions are important because chemical degradation of the chelating agent, which occurs during air regeneration, is a major problem. The objective of this project was to develop a basic understanding of catalyst regeneration and degradation chemistry. The rates of reactions of chelated iron with oxygen were measured both in the liquid phase and with gas/liquid mass transfer. The rates of chelate degradation were also measured by several methods including cycling between hydrogen sulfide absorption and oxygen regeneration conditions. A kinetics model was developed which accounts for the coupling between the regeneration and chelant degradation reactions.

  12. Removal of cadmium by combining deferasirox and desferrioxamine chelators in rats.

    PubMed

    Fatemi, S Jamilaldine; Saljooghi, Amir Shokooh; Balooch, Faezeh Dahooee; Iranmanesh, Marzieh; Golbafan, Mohammad Reza

    2012-02-01

    An investigation was conducted to evaluate the ability of two chelators, deferasirox and desferrioxamine (DFO), in removing cadmium from biological system. The potential efficiency of those chelators were investigated after cadmium administration for 60 days following two dose levels of 20 and 40 mg/kg body weight daily to male rats. However, abnormalities were observed in clinical signs after cadmium administration, such as yellowish discoloration of hair, flaccid and hypotonic muscles, irritability, weakness and loss of weight. The hypothesis that the two chelators might be more efficient as combined therapy than single therapy in removing metal ions from the body was considered. In this way, two known chelators, deferasirox and DFO were chosen and tested in the acute rat model. The chelation therapy results show that deferasirox and DFO are able (?)to remove cadmium ions from the body, while iron concentration returned to the normal level and symptoms are decreased. PMID:22134990

  13. Uptake and intracellular distribution of iron from transferrin and chelators in erythroid cells.

    PubMed

    Kontoghiorghes, G J; May, A

    1990-01-01

    Iron chelators of different physicochemical properties were studied for their ability to donate iron in vitro to uninduced K562 cells, human bone marrow cells and purified human erythroblasts. To a large extent uptake was found to be related to lipophilicity and those chelators able to deliver iron to the cells in significant amounts were also able to deliver iron to ferritin and haem. Some differences in the distribution of iron delivered was observed but no chelator showed exclusive delivery to or rejection of a particular cellular iron compartment. Several chelators could probably substitute for transferrin and be used to probe metabolic events subsequent to iron removal from transferrin. Two chelators which were excellent iron donors were also found to cause considerable inhibition of iron incorporation into haem from transferrin. The implications of this for in vivo toxicity are briefly discussed. PMID:2073459

  14. Comparative study of iron mobilization from haemosiderin, ferritin and iron(III) precipitates by chelators.

    PubMed Central

    Kontoghiorghes, G J; Chambers, S; Hoffbrand, A V

    1987-01-01

    The heteroaromatic chelators 1,2-dimethyl-3-hydroxypyrid-4-one, maltol, mimosine and 2,4-dihydroxypyridine-N-oxide, have been shown to mobilize iron from human spleen haemosiderin, ferritin and also from iron(III) precipitates, all containing equal amounts of iron, at physiological pH. In the case of almost every chelator, the least-solubilized polynuclear iron form was ferritin, whereas haemosiderin was more soluble and the iron(III) precipitate the most soluble of all. Most of the chelators were more efficient than desferrioxamine at releasing iron from ferritin, but less efficient in the removal of iron from the other two polynuclear iron forms. It is suggested that the chelator differences in iron mobilization may be related to variations in the chelator molecular structure, the protein structure, iron forms and in the mechanism of iron release. PMID:3566714

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

    PubMed Central

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

    2014-01-01

    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

  16. Long-term Chelation Therapy in Thalassaemia Major: Effect on Liver Iron Concentration, Liver Histology, and Clinical Progress

    Microsoft Academic Search

    Michael Barry; David M. Flynn; Elizabeth A. Letsky; R. A. Risdon

    1974-01-01

    A prospective trial of continuous chelation therapy in children with homozygous thalassaemia on a high transfusion regimen was started in April 1966. The effect of treatment on iron concentration in the liver and on hepatic histology was examined in 49 biopsy specimens obtained from nine chelator-treated patients and nine control patients between April 1966 and April 1973.Chelation therapy was associated

  17. Mechanism of in vivo iron chelation by pyridoxal isonicotinoyl hydrazone and other imino derivatives of pyridoxal. [Rats

    Microsoft Academic Search

    C. Hershko; S. Avramovici-Grisaru; G. Link; L. Gelfand; S. Sarel

    1981-01-01

    The source of iron chelated in vivo by the new iron-chelating agent PIH and its mechanism of excretion have been studied in normal and hypertransfused rats. PIH is able to chelate iron from both parenchymal and RE iron stores. Unlike DF, which promotes both urinary and fecal iron excretion, in this model PIH-induced iron excretion is limited almost entirely to

  18. Temporally and spectrally resolved imaging microscopy of lanthanide chelates.

    PubMed Central

    Vereb, G; Jares-Erijman, E; Selvin, P R; Jovin, T M

    1998-01-01

    The combination of temporal and spectral resolution in fluorescence microscopy based on long-lived luminescent labels offers a dramatic increase in contrast and probe selectivity due to the suppression of scattered light and short-lived autofluorescence. We describe various configurations of a fluorescence microscope integrating spectral and microsecond temporal resolution with conventional digital imaging based on CCD cameras. The high-power, broad spectral distribution and microsecond time resolution provided by microsecond xenon flashlamps offers increased luminosity with recently developed fluorophores with lifetimes in the submicrosecond to microsecond range. On the detection side, a gated microchannel plate intensifier provides the required time resolution and amplification of the signal. Spectral resolution is achieved with a dual grating stigmatic spectrograph and has been applied to the analysis of luminescent markers of cytochemical specimens in situ and of very small volume elements in microchambers. The additional introduction of polarization optics enables the determination of emission polarization; this parameter reflects molecular orientation and rotational mobility and, consequently, the nature of the microenvironment. The dual spectral and temporal resolution modes of acquisition complemented by a posteriori image analysis gated on the spatial, spectral, and temporal dimensions lead to a very flexible and versatile tool. We have used a newly developed lanthanide chelate, Eu-DTPA-cs124, to demonstrate these capabilities. Such compounds are good labels for time-resolved imaging microscopy and for the estimation of molecular proximity in the microscope by fluorescence (luminescence) resonance energy transfer and of molecular rotation via fluorescence depolarization. We describe the spectral distribution, polarization states, and excited-state lifetimes of the lanthanide chelate crystals imaged in the microscope. PMID:9591648

  19. Mechanistic Basis for Overcoming Platinum Resistance Using Copper Chelating Agents

    PubMed Central

    Liang, Zheng D.; Long, Yan; Tsai, Wen-Bin; Fu, Siqing; Kurzrock, Razelle; Gagea-Iurascu, Mihai; Zhang, Fan; Chen, Helen H.W.; Hennessy, Bryan T.; Mills, Gordon B.; Savaraj, Niramol; Kuo, Macus Tien

    2012-01-01

    Platinum (Pt)-based antitumor agents are widely used in cancer chemotherapy. Drug resistance is a major obstacle to the successful use of these agents because once drug resistance develops, other effective treatment options are limited. Recently, we have conducted a clinical trial using a copper (Cu)-lowering agent to overcome Pt drug resistance in ovarian cancer patients and the preliminary results are encouraging. In supporting this clinical study, using three pairs of cisplatin (cDDP)-resistant cell lines and two ovarian cancer cell lines derived from patients who had failed in Pt-based chemotherapy, we demonstrated that cDDP resistance associated with reduced expression of the high affinity copper transporter (hCtr1) which is also a cDDP transporter, can be preferentially re-sensitized by copper-lowering agents due to enhanced hCtr1 expression, as compared with their drug-sensitive counterparts. Such a preferential induction of hCtr1 expression in cDDP-resistant variants by Cu chelation can be explained by the mammalian Cu homeostasis regulatory mechanism. Enhanced cell-killing efficacy by a Cu-lowering agent was also observed in animal xenografts bearing cDDP-resistant cells. Finally, by analyzing a public gene expression dataset, we found that ovarian cancer patients with elevated levels of hCtr1 in their tumors, but not ATP7A and ATP7B, had more favorable outcomes after Pt-drug treatment than those expressing low hCtr1 levels. This study reveals the mechanistic basis for using Cu chelation to overcome cDDP resistance in clinical investigations. PMID:22914438

  20. Effective chelation of iron in beta thalassaemia with the oral chelator 1,2-dimethyl-3-hydroxypyrid-4-one.

    PubMed Central

    Kontoghiorghes, G J; Aldouri, M A; Hoffbrand, A V; Barr, J; Wonke, B; Kourouclaris, T; Sheppard, L

    1987-01-01

    The main iron chelator used for transfusional iron overload is desferrioxamine, which is expensive, has toxic side effects, and has to be given subcutaneously. An orally active iron chelator is therefore required. The effects of oral 1,2-dimethyl-3-hydroxypyrid-4-one on urinary iron excretion were studied in eight patients who had received multiple transfusions: four had myelodysplasia and four beta thalassaemia major. Different daily doses of the drug up to 100 mg/kg/day, alone or in combination with ascorbic acid, were used. In three patients with thalassaemia the effect of the drug was compared with that of subcutaneous desferrioxamine at the same daily dose. In all eight patients a single dose of oral 1,2-dimethyl-3-hydroxypyrid-4-one resulted in substantial urinary iron excretion, mainly in the first 12 hours. Urinary iron excretion increased with the dose and with the degree of iron loading of the patient. Giving two or three divided doses over 24 hours resulted in higher urinary iron excretion than a single dose of the same amount over the same time. In most patients coadministration of oral ascorbic acid further increased urinary iron excretion. 1,2-Dimethyl-3-hydroxypyrid-4-one caused similar iron excretion to that achieved with subcutaneous desferrioxamine at a comparable dose. In some cases the iron excretion was sufficiently high (maximum 99 mg/day) to suggest that a negative iron balance could be easily achieved with these protocols in patients receiving regular transfusions. No evidence of toxicity was observed on thorough clinical examination or haematological and biochemical testing in any of the patients. None of the patients had any symptoms that could be ascribed to the drug. These results suggest that the oral chelator 1,2-dimethyl-3-hydroxypyrid-4-one is as effective as subcutaneous desferrioxamine in increasing urinary iron excretion in patients loaded with iron. Its cheap synthesis, oral activity, and lack of obvious toxicity at effective doses suggest that it should be developed quickly and thoroughly tested for the management of transfusional iron overload. PMID:3122880

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

    NASA Astrophysics Data System (ADS)

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

    2010-11-01

    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.

  2. Statistical Analysis of Metal Chelating Activity of Centella asiatica and Erythroxylum cuneatum Using Response Surface Methodology.

    PubMed

    Mohd Salim, R J; Adenan, M I; Amid, A; Jauri, M H; Sued, A S

    2013-01-01

    The purpose of the study is to evaluate the relationship between the extraction parameters and the metal chelating activity of Centella asiatica (CA) and Erythroxylum cuneatum (EC). The response surface methodology was used to optimize the extraction parameters of methanolic extract of CA and EC with respect to the metal chelating activity. For CA, Run 17 gave optimum chelating activity with IC50 = 0.93?mg/mL at an extraction temperature of 25°C, speed of agitation at 200?rpm, ratio of plant material to solvent at 1?g?:?45?mL and extraction time at 1.5 hour. As for EC, Run 13 with 60°C, 200?rpm, 1?g?:?35?mL and 1 hour had metal chelating activity at IC50 = 0.3817?mg/mL. Both optimized extracts were further partitioned using a solvent system to evaluate the fraction responsible for the chelating activity of the plants. The hexane fraction of CA showed potential activity with chelating activity at IC50 = 0.090 and the ethyl acetate fraction of EC had IC50 = 0.120?mg/mL. The study showed that the response surface methodology helped to reduce the extraction time, temperature and agitation and subsequently improve the chelating activity of the plants in comparison to the conventional method. PMID:23533781

  3. Statistical Analysis of Metal Chelating Activity of Centella asiatica and Erythroxylum cuneatum Using Response Surface Methodology

    PubMed Central

    Mohd Salim, R. J.; Adenan, M. I.; Amid, A.; Jauri, M. H.; Sued, A. S.

    2013-01-01

    The purpose of the study is to evaluate the relationship between the extraction parameters and the metal chelating activity of Centella asiatica (CA) and Erythroxylum cuneatum (EC). The response surface methodology was used to optimize the extraction parameters of methanolic extract of CA and EC with respect to the metal chelating activity. For CA, Run 17 gave optimum chelating activity with IC50 = 0.93?mg/mL at an extraction temperature of 25°C, speed of agitation at 200?rpm, ratio of plant material to solvent at 1?g?:?45?mL and extraction time at 1.5 hour. As for EC, Run 13 with 60°C, 200?rpm, 1?g?:?35?mL and 1 hour had metal chelating activity at IC50 = 0.3817?mg/mL. Both optimized extracts were further partitioned using a solvent system to evaluate the fraction responsible for the chelating activity of the plants. The hexane fraction of CA showed potential activity with chelating activity at IC50 = 0.090 and the ethyl acetate fraction of EC had IC50 = 0.120?mg/mL. The study showed that the response surface methodology helped to reduce the extraction time, temperature and agitation and subsequently improve the chelating activity of the plants in comparison to the conventional method. PMID:23533781

  4. Advances in understanding atmospheric corrosion of iron. I. Rust characterisation of ancient ferrous artefacts exposed to indoor atmospheric corrosion

    Microsoft Academic Search

    Ph Dillmann; F Mazaudier; S Hœrlé

    2004-01-01

    Metallic substrates and rust layers of several hundred year old (y.o.) ferrous artefacts were characterised. Composition, structure and porosity of the rust were analysed by different methods: OM, SEM, EDS, EPMA, XRD, ?XRD, SAXS, BET and mercury porosimetry.Several important parameters to describe an old rust layer were determined and measured. These parameters will be used for the modelling of long-term

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

    Microsoft Academic Search

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

    2001-01-01

    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

  6. Diversity of Ferrous Iron-Oxidizing, Nitrate-Reducing Bacteria and their Involvement in Oxygen-Independent Iron Cycling

    Microsoft Academic Search

    Kristina L. Straub; Wilhelm A. Schönhuber; Berit E. E. Buchholz-Cleven; Bernhard Schink

    2004-01-01

    In previous studies, three different strains (BrG1, BrG2, and BrG3) of ferrous iron-oxidizing, nitrate-reducing bacteria were obtained from freshwater sediments. All three strains were facultative anaerobes and utilized a variety of organic substrates and molecular hydrogen with nitrate as electron acceptor. In this study, analyses of 16S rDNA sequences showed that strain BrG1 was affiliated with the genus Acidovorax, strain

  7. TOF-SIMS study on the adsorption behavior of mixtures of a phosphite and a friction modifier onto ferrous material

    Microsoft Academic Search

    A. Murase; T. Ohmori

    2003-01-01

    The adsorption behavior of a mixture of lubricant additives onto ferrous materials has been investigated by time-of-flight secondary ion mass spectrometry (TOF-SIMS). Tri-n-butylphosphite (TBPi) and di-n-butylphosphite (DBPi) were selected as model compounds of phosphate-type additives and palmitic acid (PA), oleyl amine (OA) and glycerol mono-oleate (GM) were selected as model compounds of friction modifiers. The mixtures of one of the

  8. The ferrous-dioxygen intermediate in human cytochrome P450 3A4. Substrate dependence of formation and decay kinetics.

    PubMed

    Denisov, Ilia G; Grinkova, Yelena V; Baas, Bradley J; Sligar, Stephen G

    2006-08-18

    The oxy-ferrous complex is the first of three branching intermediates in the catalytic cycle of cytochrome P450, in which the total efficiency of substrate turnover is curtailed by the side reaction of autoxidation. For human membrane-bound cytochromes P450, the oxy complex is believed to be the primary source of cytotoxic superoxide and peroxide, although information on the properties and stability of this intermediate is lacking. Here we document stopped-flow spectroscopic studies of the formation and decay of the oxy-ferrous complex in the most abundant human cytochrome P450 (CYP3A4) as a function of temperature in the substrate-free and substrate-bound form. CYP3A4 solubilized in purified monomeric form in nanoscale POPC bilayers is functionally and kinetically homogeneous. In substrate-free CYP3A4, the oxy complex is extremely unstable with a half-life of approximately 30 ms at 5 degrees C. Saturation with testosterone or bromocriptine stabilizes the oxy-ferrous intermediate. Comparison of the autoxidation rates with the available data on CYP3A4 turnover kinetics suggests that the oxy complex may be an important route for uncoupling. PMID:16762915

  9. Were mercury emission factors for Chinese non-ferrous metal smelters overestimated? Evidence from onsite measurements in six smelters.

    PubMed

    Zhang, Lei; Wang, Shuxiao; Wu, Qingru; Meng, Yang; Yang, Hai; Wang, Fengyang; Hao, Jiming

    2012-12-01

    Non-ferrous metal smelting takes up a large proportion of the anthropogenic mercury emission inventory in China. Zinc, lead and copper smelting are three leading sources. Onsite measurements of mercury emissions were conducted for six smelters. The mercury emission factors were 0.09-2.98 g Hg/t metal produced. Acid plants with the double-conversion double-absorption process had mercury removal efficiency of over 99%. In the flue gas after acid plants, 45-88% was oxidized mercury which can be easily scavenged in the flue gas scrubber. 70-97% of the mercury was removed from the flue gas to the waste water and 1-17% to the sulfuric acid product. Totally 0.3-13.5% of the mercury in the metal concentrate was emitted to the atmosphere. Therefore, acid plants in non-ferrous metal smelters have significant co-benefit on mercury removal, and the mercury emission factors from Chinese non-ferrous metal smelters were probably overestimated in previous studies. PMID:22892573

  10. Chelate effects in sulfate binding by amide/urea-based ligands.

    PubMed

    Jia, Chuandong; Wang, Qi-Qiang; Begum, Rowshan Ara; Day, Victor W; Bowman-James, Kristin

    2015-07-01

    The influence of chelate and mini-chelate effects on sulfate binding was explored for six amide-, amide/amine-, urea-, and urea/amine-based ligands. Two of the urea-based hosts were selective for SO4(2-) in water-mixed DMSO-d6 systems. Results indicated that the mini-chelate effect provided by a single urea group with two NH binding sites appears to provide enhanced binding over two amide groups. Furthermore, additional urea binding sites incorporated into the host framework appeared to overcome to some extent competing hydration effects with increasing water content. PMID:25966663

  11. Influence of chelating agents in eluent on the separation factor of lithium isotopes

    Microsoft Academic Search

    D. W. Kim; J. H. Jung

    1989-01-01

    The influence of chelating agents on the separation factor, , of lithium isotopes separation was studied by ion exchange elution chromatography. Eluents contained the chelating agent having different number of coordination sites. The chelating agents used in eluent were Na-glycine (Na–Gly), 2Na-iminodiacetic acid (2Na-IDA), 3Na-nitrilotriacetic acid (3Na-NTA), and 4Na-ethylenediaminetetraacetic acid (4Na-EDTA). The ion exchanger was Dowex 50W-X8, sulfonic acid type,

  12. Removal of vanadium by combining desferrioxamine and deferiprone chelators in rats

    Microsoft Academic Search

    Solmaz Tubafard; S. Jamilaldine Fatemi; Amir Shokooh Saljooghi; Masoud Torkzadeh

    2010-01-01

    Investigations were conducted to evaluate the ability of two chelators, desferrioxamine (DFO), and deferiprone (1,2-dimethy1-3-hydroxypyride-4-one,\\u000a L1), for the excretion of vanadium after a period of administration of vanadium salts in 6-week-old male Wistar rats. Immediately\\u000a after 60 days of vanadium administration, the rats received chelators (L1, DFO or L1 + DFO) for a period of 1 week. Chelators were given orally (L1), intraperitoneally (DFO),

  13. Development of a New Ferrous Aluminosilicate Refractory Material for Investment Casting of Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Yuan, Chen; Jones, Sam; Blackburn, Stuart

    2012-12-01

    Investment casting is a time-consuming, labour intensive process, which produces complex, high value-added components for a variety of specialised industries. Current environmental and economic pressures have resulted in a need for the industry to improve current casting quality, reduce manufacturing costs and explore new markets for the process. Alumino-silicate based refractories are commonly used as both filler and stucco materials for ceramic shell production. A new ceramic material, norite, is now being produced based on ferrous aluminosilicate chemistry, having many potential advantages when used for the production of shell molds for casting aluminum alloy. This paper details the results of a direct comparison made between the properties of a ceramic shell system produced with norite refractories and a typical standard refractory shell system commonly used in casting industry. A range of mechanical and physical properties of the systems was measured, and a full-scale industrial casting trial was also carried out. The unique properties of the norite shell system make it a promising alternative for casting aluminum based alloys in the investment foundry.

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

    PubMed Central

    Ades, A E; Kazantzis, G

    1988-01-01

    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

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

    E-print Network

    Hsu, Han

    2014-01-01

    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...

  16. Photoelectro-Fenton mineralization of phenol through optimization of ferrous regeneration.

    PubMed

    Shih, Yu-Jen; Su, Hsiao-Ting; Huang, Yao-Hui

    2013-09-01

    The degradation of phenol in acidic solution at pH 3 has been investigated under various photo- and electrochemical conditions. A laboratory-scale reactor on which were mounted net electrodes (RuO2/IrO2-coated Ti anodes (DSA) and stainless steel cathodes) and 254 nm UV lamps was established to effectively reduce ferric reagents. The experimental results of the photoelectron-chemical reaction suggested that the current efficiency of reducing ferric ion was improved by increasing the number of electrodes used, and the UV lamps were important to inducing the reduction of ferric carboxylates, which were the major intermediates that were formed upon a particular degree of phenol oxidation. Accordingly, the addition of an initial concentration of 400 ppm ferrous salt and 10,200 ppm hydrogen peroxide (in a continuous mode) resulted in the removal of over 92 % of TOC (initial phenol?=?2,000 ppm, TOC?=?1,532 ppm) by 4 h of the photoelectro-Fenton and the sequential 2 h of the photo-Fenton processes. HPLC was utilized to monitor the formation of aromatic and carboxylate byproducts, and revealed that the aid of photo irradiation eliminated most of the oxalate residue from the final solution, which would have contributed to the 25 % of the TOC that was inactive in the electrolytic system. PMID:23589255

  17. [FEATURES OF THE IMMUNE GENETIC PARAMETERS IN WORKERS IN NON-FERROUS METAL INDUSTRY].

    PubMed

    Dolgikh, O V; Krivtsov, A V; Lykhina, T S; Bubnova, O A; Lanin, D V; Vdovina, N A; Luzhetsky, K P; Andreeva, E E

    2015-01-01

    There was performed a comparative analysis of immunogenetic indices in non-ferrous metallurgy employees under the exposure to different combinations of harmful occupational factors. The combined effect of chlorine and vanadium fumes, noise, overall vibration appeared to be associated with the gene polymorphism of cytokine regulation--VEGF and TNF (p < 0.05). In workers the combination offactors such as dust containing silicon dioxide, noise, elevated environmental thermal load was associated with cytochrome p450 gene polymorphism, allele variation ofwhich is formed owing to the homozygous genotype. At the same time there was observed an excess production of specific antibodies to vanadium and silicon, significantly differed from that of the indices in the reference group. There are proposed genetic (CYP1A1, VEGF TNFalfa) and immunological (IgG to vanadium and silicon) indices as markers of susceptibility and effect in health risk assessment of different combinations of harmful occupational factors, which will allow to increase the availability of laboratory control during surveillance activities at the objects. PMID:26155646

  18. INTERPRETATION OF AT-LINE SPECTRA FROM AFS-2 BATCH #3 FERROUS SULFAMATE TREATMENT

    SciTech Connect

    Kyser, E.; O'Rourke, P.

    2013-12-10

    Spectra from the “at-line” spectrometer were obtained during the ferrous sulfamate (FS) valence adjustment step of AFS-2 Batch #3 on 9/18/2013. These spectra were analyzed by mathematical principal component regression (PCR) techniques to evaluate the effectiveness of this treatment. Despite the complications from Pu(IV), we conclude that all Pu(VI) was consumed during the FS treatment, and that by the end of the treatment, about 85% was as Pu(IV) and about 15% was as Pu(III). Due to the concerns about the “odd” shape of the Pu(IV) peak and the possibility of this behavior being observed in the future, a follow-up sample was sent to SRNL to investigate this further. Analysis of this sample confirmed the previous results and concluded that it “odd” shape was due to an intermediate acid concentration. Since the spectral evidence shows complete reduction of Pu(VI) we conclude that it is appropriate to proceed with processing of this the batch of feed solution for HB-Line including the complexation of the fluoride with aluminum nitrate.

  19. A Speciation Study on the Perturbing Effects of Iron Chelators on the Homeostasis of Essential Metal Ions

    PubMed Central

    2015-01-01

    A number of reports have appeared in literature calling attention to the depletion of essential metal ions during chelation therapy on ?-thalassaemia patients. We present a speciation study to determine how the iron chelators used in therapy interfere with the homeostatic equilibria of essential metal ions. This work includes a thorough analysis of the pharmacokinetic properties of the chelating agents currently in clinical use, of the amounts of iron, copper and zinc available in plasma for chelation, and of all the implied complex formation constants. The results of the study show that a significant amount of essential metal ions is complexed whenever the chelating agent concentration exceeds the amount necessary to coordinate all disposable iron —a frequently occurring situation during chelation therapy. On the contrary, copper and zinc do not interfere with iron chelation, except for a possible influence of copper on iron speciation during deferiprone treatment. PMID:26192307

  20. Selective divalent copper chelation for the treatment of diabetes mellitus.

    PubMed

    Cooper, G J S

    2012-01-01

    Oxidative stress and mitochondrial dysfunction have been identified by many workers as key pathogenic mechanisms in ageing-related metabolic, cardiovascular and neurodegenerative diseases (for example diabetes mellitus, heart failure and Alzheimer's disease). However, although numerous molecular mechanisms have been advanced to account for these processes, their precise nature remains obscure. This author has previously suggested that, in such diseases, these two mechanisms are likely to occur as manifestations of a single underlying disturbance of copper regulation. Copper is an essential but highly-toxic trace metal that is closely regulated in biological systems. Several rare genetic disorders of copper homeostasis are known in humans: these primarily affect various proteins that mediate intracellular copper transport processes, and can lead either to tissue copper deficiency or overload states. These examples illustrate how impaired regulation of copper transport pathways can cause organ damage and provide important insights into the impact of defects in specific molecular processes, including those catalyzed by the copper-transporting ATPases, ATP7A (mutated in Menkes disease), ATP7B (Wilson's disease), and the copper chaperones such as those for cytochrome c oxidase, SCO1 and SCO2. In diabetes, impaired copper regulation manifests as elevations in urinary CuII excretion, systemic chelatable-CuII and full copper balance, in increased pro-oxidant stress and defective antioxidant defenses, and in progressive damage to the blood vessels, heart, kidneys, retina and nerves. Linkages between dysregulated copper and organ damage can be demonstrated by CuII-selective chelation, which simultaneously prevents/reverses both copper dysregulation and organ damage. Pathogenic structures in blood vessels that contribute to binding and localization of catalytically-active CuII probably include advanced glycation end products (AGEs), as well as atherosclerotic plaque: the latter probably undergoes AGE-modification itself. Defective copper regulation mediates organ damage through two general processes that occur simultaneously in the same individual: elevation of CuII-mediated pro-oxidant stress and impairment of copper-catalyzed antioxidant defence mechanisms. This author has proposed that diabetes-evoked copper dysregulation is an important new target for therapeutic intervention to prevent/reverse organ damage in diabetes, heart failure, and neurodegenerative diseases, and that triethylenetetramine (TETA) is the first in a new class of anti-diabetic molecules, which function by targetting these copper-mediated pathogenic mechanisms. TETA prevents tissue damage and causes organ regeneration by acting as a highly-selective CuII chelator which suppresses copper-mediated oxidative stress and restores anti-oxidant defenses. My group has employed TETA in a comprehensive programme of nonclinical studies and proof-of-principle clinical trials, thereby characterizing copper dysregulation in diabetes and identifying numerous linked cellular and molecular mechanisms though which TETA exerts its therapeutic actions. Many of the results obtained in nonclinical models with respect to the molecular mechanisms of diabetic organ damage have not yet been replicated in patients' tissues so their applicability to the human disease must be considered as inferential until the results of informative clinical studies become available. Based on evidence from the studies reviewed herein, trientine is now proceeding into the later stages of pharmaceutical development for the treatment of heart failure and other diabetic complications. PMID:22455587

  1. BENCH-SCALE RECOVERY OF LEAD USING AN ELECTROMEMBRANE/CHELATION PROCESS

    EPA Science Inventory

    This report presents the results of a bench-scale treatability test to investigate key process parameters influencing an innovative chelation electrodeposition process for recovery of lead from contaminated sons. thylenediamine tetraacetic acid (EDTA) and diethylenetriamine penta...

  2. BENCH-SCALE RECOVERY OF LEAD USING AND ELECTRO- MEMBRANE/CHELATION PROCESS

    EPA Science Inventory

    This report presents the results of a bench-scale treatability test to investigate key process parameters influencing an innovative chelation electrodeposition process for recovery of lead from contaminated sons. thylenediamine tetraacetic acid (EDTA) and diethylenetriamine penta...

  3. Thermal Stability of Various Chelates that are Used in the Oilfield 

    E-print Network

    Sokhanvarian, Khatere

    2012-10-24

    wells. GLDA is environmentally friendly, which makes it favorable. One of the concerns with these chelates is their thermal stability at high temperatures because if they degrade at high temperatures, they may lose their functionality. This study...

  4. Enhanced Nucleophilic Fluorination and Radiofluorination of Organosilanes Appended with Potassium-Chelating Leaving Groups

    PubMed Central

    Al-huniti, Mohammed H.; Lu, Shuiyu; Pike, Victor W.; Lepore, Salvatore D.

    2014-01-01

    Here we aimed to explore the feasibility of enhancing the fluorination of organosilanes by appending potassium-chelating groups to the substrates. For this purpose, eight organosilanes were prepared in which a linear or cyclic leaving group, with putative potassium-chelating ability, was attached covalently to a congested silicon atom via an ether linkage to serve as a potential nucleophilic assisting leaving group (NALG). Organosilicon-NALGs with expected strong potassium-chelating capability enhanced reactions with potassium fluoride in acetonitrile to produce organofluorosilanes without any need to separately add phase transfer reagent. Similar rate enhancements were also observed with cyclotron-produced [18F]fluoride ion (t1/2 = 109.7 min, ?+ = 97%) in the presence of potassium carbonate in MeCN-0.5% H2O. This study found that metal-chelating NALG units can accelerate fluorination and radiofluorination reactions at sterically crowded silicon atoms. PMID:24653526

  5. Chelation of chromium(VI) by combining deferasirox and deferiprone in rats.

    PubMed

    Iranmanesh, Marzieh; Fatemi, S Jamil A; Ebrahimpour, Roza; Dahooee Balooch, Faezeh

    2013-06-01

    The present research is aimed to characterize the potential efficiency of two chelators after chromium(VI) administration for 60 days following two doses of 15 and 30 mg/kg chromium(VI) per body weight daily to male rats. However, the hypothesis that the two chelators might be more efficient as combined therapy than as single therapy in removing chromium(VI) from rat organs was considered. In this way, two known chelators deferasirox and deferiprone were chosen and given orally as a single or combined therapy for a period of 1 week. Chromium(VI) and iron concentrations in tissues were determined by flame atomic absorption spectroscopy. The combined chelation therapy results show that deferasirox and deferiprone are able to remove chromium(VI) ions from various tissues while iron concentration returned to normal levels and symptoms also decreased. PMID:23670101

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

    E-print Network

    Atanasijevic, Tatjana

    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 ...

  7. Enhancement of bismuth antibacterial activity with lipophilic thiol chelators.

    PubMed Central

    Domenico, P; Salo, R J; Novick, S G; Schoch, P E; Van Horn, K; Cunha, B A

    1997-01-01

    The antibacterial properties of bismuth are greatly enhanced when bismuth is combined with certain lipophilic thiol compounds. Antibacterial activity was enhanced from 25- to 300-fold by the following seven different thiols, in order of decreasing synergy: 1,3-propanedithiol, dimercaprol (BAL), dithiothreitol, 3-mercapto-2-butanol, beta-mercaptoethanol, 1-monothioglycerol, and mercaptoethylamine. The dithiols produced the greatest synergy with bismuth at optimum bismuth-thiol molar ratios of from 3:1 to 1:1. The monothiols were generally not as synergistic and required molar ratios of from 1:1 to 1:4 for optimum antibacterial activity. The most-active mono- or dithiols were also the most soluble in butanol. The intensity of the yellow formed by bismuth-thiol complexes reflected the degree of chelation and correlated with antibacterial potency at high molar ratios. The bismuth-BAL compound (BisBAL) was active against most bacteria, as assessed by broth dilution, agar diffusion, and agar dilution analyses. Staphylococci (MIC, 5 to 7 microM Bi3+) and Helicobacter pylori (MIC, 2.2 microM) were among the most sensitive bacteria. Gram-negative bacteria were sensitive (MIC, < 17 microM). Enterococci were relatively resistant (MIC, 63 microM Bi3+). The MIC range for anaerobes was 15 to 100 microM Bi3+, except for Clostridium difficile (MIC, 7.5 microM). Bactericidal activity averaged 29% above the MIC. Bactericidal activity increased with increasing pH and/or increasing temperature. Bismuth-thiol solubility, stability, and antibacterial activity depended on pH and the bismuth-thiol molar ratio. BisBAL was stable but ineffective against Escherichia coli at pH 4. Activity and instability (reactivity) increased with increasing alkalinity. BisBAL was acid soluble at a molar ratio of greater than 3:2 and alkaline soluble at a molar ratio of less than 2:3. In conclusion, certain lipophilic thiol compounds enhanced bismuth antibacterial activity against a broad spectrum of bacteria. The activity, solubility, and stability of BisBAL were strongly dependent on the pH, temperature, and molar ratio. Chelation of bismuth with certain thiol agents enhanced the solubility and lipophilicity of this cationic heavy metal, thereby significantly enhancing its potency and versatility as an antibacterial agent. PMID:9257744

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

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

    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.

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

    PubMed

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

    2014-01-24

    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

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

    Microsoft Academic Search

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

    2008-01-01

    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

  11. Chelating extraction and recovery of cadmium from soil using pyridine-2,6-dicarboxylic acid

    Microsoft Academic Search

    Andrew P. K. Hong; Ting-Chien Chen

    1996-01-01

    Heavy metal contamination of soil frequently occurs at hazardous waste sites in many countries of the industrialized world. The use of chelating agents to extract heavy metals from contaminated soils is seen as a treatment method. This research investigated the use of chelator pyridine-2,6-dicarboxylic acid (PDA) to extract cadmium from a spiked soil. Batch equilibration experiments over 24-hr periods were

  12. Selective uptake and recovery of cadmium (II) by microcapsule containing chelating resin

    Microsoft Academic Search

    Dhruv K. Singh; Meenakshi Srivastava

    2005-01-01

    A chelate resin that adsorbed 2-(p-sulphophenylazo)-1,8-dihydroxy-3,6-naphthalene disulfonate ion on an anion exchange resin was synthesized, and then polystyrene microcapsules containing the chelate resin were prepared by interfacial polymerization with W\\/O\\/W emulsions. The uptake to Cd2+, Co2+, Ni2+, Zn2+, Cu2+ and Zr4+ ions into the microcapsules was studied at 25°C. The adsorption rate of Cd2+ ion to the microcapsules was about

  13. Coordination chemistry with pyrazole-based chelating ligands: molecular structural aspects

    Microsoft Academic Search

    Rabindranath Mukherjee

    2000-01-01

    Pyrazole-based chelating ligands form a variety of coordination complexes with a number of metal ions, providing varying coordination geometry and nuclearity. Recent years have seen considerable interest in the designing of various pyrazole-based ligands and to study their structural properties to serve specific stereochemical requirement of a particular metal-binding site. Using over 120 pyrazole-based chelating ligands, the stereochemical properties of

  14. Inhibition of lipid peroxidation by a new family of iron chelators

    Microsoft Academic Search

    Samar Rachidi; Charles Coudray; Paul Baret; Gisèle Gelon; Jean-Louis Pierre; Alain Favier

    1994-01-01

    Catechol derived siderophores are the most powerful currently known iron chelators. We have intended tripodal ligands built\\u000a with o,o? dihydroxy biaryl subunits (A, B, and C). We described antioxidant properties of this new family of iron chelators.\\u000a Superoxidedependent hydroxyl radical system was used. Peroxidation of different lipid-containing systems (liposomes, erythrocyte\\u000a membrane ghosts, tissue homogenates) were also investigated.\\u000a \\u000a The antioxidant properties

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

    Microsoft Academic Search

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

    2011-01-01

    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

  16. Effects of chelators on iron uptake and release by the brain in the rat

    Microsoft Academic Search

    A. Crowe; E. H. Morgan

    1994-01-01

    The iron chelators desferrioxamine (DFO), pyridoxal isonicotinoyl hydrazone (PIH), 2,2'-bipyridine, diethylenetriamine penta-acetic acid (DTPA) and 1,2 dimethyl-3-hydroxy pyrid-4-one (CP20) were analysed for their ability to change59Fe uptake and release from the brain of 15- and 63-day rats either during or after intravenous injection of59Fe-125I-transferrin. DTPA was the only chelator unable to significantly reduce iron uptake into the brain of 15-day

  17. Synthesis, Characterisaton and Antimicrobial Studies of Cobalt(III) Chelates of Some Lawsone Derivatives

    Microsoft Academic Search

    V. D. Kelkar; R. R. Gokhale; H. R. Gholap

    1998-01-01

    Cobalt(III) chelates of lawsone, HL (2-hydroxy-1, 4-naphthalenedione), 3-chlorolawsone, phthiocol (3-methytlawsone) and their 1-oximes have been synthesised from chloropentamminecobalt(III) chloride via ligand replacement reactions. The analytical and thermogravimetric data indicate that the chelates have the general molecular composition CoL3·nH2O where n = 4 or 5. The spectral data reveal that O-O in lawsones and N-O in lawsonemonoximes coordinate with Co(III). An

  18. Synergistic topical photoprotection by a combination of the iron chelator 2-furildioxime and sunscreen

    Microsoft Academic Search

    Donald L Bissett; James F McBride

    1996-01-01

    Background: Iron is a factor in skin photodamage, apparently by way of its participation in oxygen radical production. Certain topical iron chelators are photoprotective.Objective: Our purpose was to determine the level of topical photoprotection provided by the iron chelator 2-furildioxime (FDO) in combination with sunscreen in short- and long-term photoprotection models.Methods: Guinea pigs were treated topically with FDO, sunscreen, and

  19. Iron chelators deferoxamine and diethylenetriamine pentaacetic acid induce apoptosis in ovarian carcinoma

    Microsoft Academic Search

    Laurent Brard; Cornelius O. Granai; Narasimha Swamy

    2006-01-01

    Objectives.Ovarian cancer remains a leading cause of death in women and development of new therapies is essential. Deprivation of iron (Fe), an essential micro-nutrient, by chelation is known to inhibit proliferation of several human cancers but its potential in ovarian cancer treatment remains unknown. We have evaluated the anti-proliferative activities of iron chelators, deferoxamine (DFO), and diethylenetriamine pentaacetic acid (DTPA),

  20. Orally Active Alpha-Ketohydroxypyridine Iron Chelators: Effects on Iron and Other Metal Mobilisations

    Microsoft Academic Search

    George J. Kontoghiorghes

    1987-01-01

    Increased 59Fe excretion was observed following the intragastric and intraperitoneal administration of 1-ethyl- and 1-methyl- 2-methyl-3-hydroxypyrid-4-ones in normal and iron-loaded, 59Fe-labelled mice, respectively. Administration of these chelators and desferrioxamine parenterally or intragastrically to an iron-loaded rabbit caused no increase in Cu, Zn, Ca or Mg urinary excretion. Iron mobilisation was also observed following the incubation of the chelators with ferritin

  1. Present status and future prospects of oral iron chelation therapy in thalassaemia and other diseases

    Microsoft Academic Search

    George J. Kontoghiorghes

    1993-01-01

    In the last few years we have witnessed the emergence of oral chelation which is a new form of therapy for transfusional iron-loaded\\u000a patients in thalassaemia and other refractory anaemias. The need for a cheap, non-toxic, orally effective iron chelator is\\u000a paramount because it could potentially save the lives of many thousands of patients. At present, less than 10% of

  2. Comparative efficacy and toxicity of desferrioxamine, deferiprone and other iron and aluminium chelating drugs.

    PubMed

    Kontoghiorghes, G J

    1995-10-01

    The efficacy and toxicity aspects of the iron and aluminium chelating drugs desferrioxamine and deferiprone (L1, 1,2-dimethyl-3-hydroxypyrid-4-one), have been compared. Major emphasis was given in the use of these two and also of other chelators in conditions of iron overload, imbalance and toxicity, as well as the incidence and possible causes of toxic side effects in both animals and humans. The chemical basis of chelation and the interaction of these chelators with the iron pools are discussed within the context of clinical application in iron overload and other conditions such as renal dialysis, rheumatoid arthritis, cancer, heart disease, malaria, etc. The design and development of new orally active alpha-ketohydroxypyridine and other chelators are considered and compared with 14 other chelators which have been previously tested in man for the removal of iron, most of which, however, were later abandoned because of low efficacy or major toxicity. The design of new therapeutic protocols based on the pharmacological, toxicological and metabolic transformation properties of the chelating drugs is also being considered, within the context of maximising their efficacy and minimising their toxicity. Overall, oral deferiprone appears to be as effective as s.c. desferrioxamine in the removal of iron and aluminium in man and to have a similar but different toxicity profile from desferrioxamine in both animals and man. The low cost and oral activity of deferiprone will make it the drug of choice for the vast majority of patients, who are not currently being chelated either because they cannot afford the high cost of desferrioxamine therapy or are not complying or have toxic side effects with its s.c. administration. PMID:7482575

  3. Comparative efficacy and toxicity of desferrioxamine, deferiprone and other iron and aluminium chelating drugs

    Microsoft Academic Search

    George J. Kontoghiorghes

    1995-01-01

    The efficacy and toxicity aspects of the iron and aluminium chelating drugs desferrioxamine and deferiprone (L1, 1,2-dimethyl-3-hydroxypyrid-4-one), have been compared. Major emphasis was given in the use of these two and also of other chelators in conditions of iron overload, imbalance and toxicity, as well as the incidence and possible causes of toxic side effects in both animals and humans.

  4. Spectroscopic properties of azo metal chelate dyes as optical recording materials

    Microsoft Academic Search

    Shuangqing Wang; Huijun Xu; Shuyin Shen; Kai Liu

    2003-01-01

    An azo dye, 2-(2-thiazolylazo)-5-diethylaminophenol(TAP), and its cobalt, copper and nickel chelates have been synthesized, which can be used as optical recording materials in DVD-R. The absorption spectra show a great difference in different metal chelates. This may be attributed to the different modes of coordination of metal ions to the azo dye. The structural consideration responsible for the difference are

  5. Spectroscopic properties of azo metal chelate dyes as optical recording materials

    NASA Astrophysics Data System (ADS)

    Wang, Shuangqing; Xu, Huijun; Shen, Shuyin; Liu, Kai

    2003-04-01

    An azo dye, 2-(2-thiazolylazo)-5-diethylaminophenol(TAP), and its cobalt, copper and nickel chelates have been synthesized, which can be used as optical recording materials in DVD-R. The absorption spectra show a great difference in different metal chelates. This may be attributed to the different modes of coordination of metal ions to the azo dye. The structural consideration responsible for the difference are also discussed.

  6. Diagnostic chelation challenge with DMSA: a biomarker of long-term mercury exposure?

    PubMed Central

    Frumkin, H; Manning, C C; Williams, P L; Sanders, A; Taylor, B B; Pierce, M; Elon, L; Hertzberg, V S

    2001-01-01

    Chelation challenge testing has been used to assess the body burden of various metals. The best-known example is EDTA challenge in lead-exposed individuals. This study assessed diagnostic chelation challenge with dimercaptosuccinic acid (DMSA) as a measure of mercury body burden among mercury-exposed workers. Former employees at a chloralkali plant, for whom detailed exposure histories were available (n = 119), and unexposed controls (n = 101) completed 24-hr urine collections before and after the administration of two doses of DMSA, 10 mg/kg. The urinary response to DMSA was measured as both the absolute change and the relative change in mercury excretion. The average 24-hr mercury excretion was 4.3 microg/24 hr before chelation, and 7.8 microg/24 hr after chelation. There was no association between past occupational mercury exposure and the urinary excretion of mercury either before or after DMSA administration. There was also no association between urinary mercury excretion and the number of dental amalgam surfaces, in contrast to recent published results. We believe the most likely reason that DMSA chelation challenge failed to reflect past mercury exposure was the elapsed time (several years) since the exposure had ended. These results provide normative values for urinary mercury excretion both before and after DMSA challenge, and suggest that DMSA chelation challenge is not useful as a biomarker of past mercury exposure. PMID:11266328

  7. Translational downregulation of HSP90 expression by iron chelators in neuroblastoma cells.

    PubMed

    Sidarovich, Viktoryia; Adami, Valentina; Gatto, Pamela; Greco, Valentina; Tebaldi, Toma; Tonini, Gian Paolo; Quattrone, Alessandro

    2015-01-01

    Iron is an essential cellular nutrient, being a critical cofactor of several proteins involved in cell growth and replication. Compared with normal cells, neoplastic cells have been shown to require a greater amount of iron, thus laying the basis for the promising anticancer activity of iron chelators. In this work, we evaluated the effects of molecules with iron chelation activity on neuroblastoma (NB) cell lines. Of the 17 iron chelators tested, six reduced cell viability of two NB cell lines with an inhibition of growth of 50% below 10 µM; four of the six molecules-ciclopirox olamine (CPX), piroctone, 8-hydroxyquinoline, and deferasirox-were also shown to efficiently chelate intracellular iron within minutes after addition. Effects on cell viability of one of the compounds, CPX, were indeed dependent on chelation of intracellular iron and mediated by both G0/G1 cell cycle block and induction of apoptosis. By combined transcriptome and translatome profiling we identified early translational downregulation of several members of the heat shock protein group as a specific effect of CPX treatment. We functionally confirmed iron-dependent depletion of HSP90 and its client proteins at pharmacologically achievable concentrations of CPX, and we extended this effect to piroctone, 8-hydroxyquinoline, and deferasirox. Given the documented sensitivity of NB cells to HSP90 inhibition, we propose CPX and other iron chelators as investigational antitumor agents in NB therapy. PMID:25564462

  8. Selective determination of mitochondrial chelatable iron in viable cells with a new fluorescent sensor.

    PubMed Central

    Petrat, Frank; Weisheit, Daniela; Lensen, Martina; de Groot, Herbert; Sustmann, Reiner; Rauen, Ursula

    2002-01-01

    Mitochondrial chelatable ("redox-active") iron is considered to contribute to several human diseases, but has not yet been characterized in viable cells. In order to determine this iron pool, we synthesized a new fluorescent indicator, rhodamine B-[(1,10-phenanthrolin-5-yl)aminocarbonyl]benzyl ester (RPA). In a cell-free system, RPA fluorescence was strongly and stoichiometrically quenched by Fe(2+). RPA selectively accumulated in the mitochondria of cultured rat hepatocytes. The intramitochondrial RPA fluorescence was quenched when iron was added to the cells in a membrane-permeant form. It increased when the mitochondrial chelatable iron available to the probe was experimentally decreased by the membrane-permeant transition metal chelators pyridoxal isonicotinoyl hydrazone and 1,10-phenanthroline. The concentration of mitochondrial chelatable iron in cultured rat hepatocytes, quantified from the increase in RPA fluorescence after addition of pyridoxal isonicotinoyl hydrazone, was found to be 12.2 +/- 4.9 microM. Inhibition of haem synthesis with succinylacetone did not alter the signal obtained in hepatocytes, but a rapid increase in the concentration of mitochondrial chelatable iron was observed in human erythroleukaemia K562 cells. In conclusion, RPA enables the selective determination of the highly physiologically and pathophysiologically interesting mitochondrial pool of chelatable iron in intact cells and to record the time course of alterations of this pool. PMID:11829750

  9. Alternative chelating agents: evaluation of the ready biodegradability and complexation properties.

    PubMed

    Martins, João G; Neto, Isabel F F; Pinto, Isabel S S; Soares, Eduardo V; Barros, Maria Teresa; Soares, Helena M V M

    2014-01-01

    The ready biodegradability of four chelating agents, N,N'-(S,S)-bis[1-carboxy-2-(imidazol-4-yl)ethyl]ethylenediamine (BCIEE), N'-ethylenedi-L-cysteine (EC), N,N'-bis (4-imidazolymethyl)ethylenediamine (EMI) and 2,6-pyridine dicarboxylic acid (PDA), was tested according to the OECD guideline for testing of chemicals. PDA proved to be a readily biodegradable substance. However, none of the other three compounds were degraded during the 28 days of the test. Chemical simulations were performed for the four compounds in order to understand their ability to complex with some metal ions (Ca, Cd, Co, Cu, Fe, Mg, Mn, Ni, Pb, Zn) and discuss possible applications of these chelating agents. Two different conditions were simulated: (i) in the presence of the chelating agent and one metal ion, and (ii) in the simultaneous presence of the chelating agent and all metal ions with an excess of Ca. For those compounds that were revealed not to be readily biodegradable (BCIEE, EC and EMI), applications were evaluated where this property was not fundamental or even not required. Chemical simulations pointed out that possible applications for these chelating agents are: food fortification, food process, fertilizers, biocides, soil remediation and treatment of metal poisoning. Additionally, chemical simulations also predicted that PDA is an efficient chelating agent for Ca incrustations removal, detergents and for pulp metal ions removal process. PMID:24279626

  10. Chelation of mitochondrial iron prevents seizure-induced mitochondrial dysfunction and neuronal injury.

    PubMed

    Liang, Li-Ping; Jarrett, Stuart G; Patel, Manisha

    2008-11-01

    Chelatable iron is an important catalyst for the initiation and propagation of free radical reactions and implicated in the pathogenesis of diverse neuronal disorders. Studies in our laboratory have shown that mitochondria are the principal source of reactive oxygen species production after status epilepticus (SE). We asked whether SE modulates mitochondrial iron levels by two independent methods and whether consequent mitochondrial dysfunction and neuronal injury could be ameliorated with a cell-permeable iron chelator. Kainate-induced SE resulted in a time-dependent increase in chelatable iron in mitochondrial but not cytosolic fractions of the rat hippocampus. Systemically administered N,N'-bis (2-hydroxybenzyl) ethylenediamine-N,N'-diacetic acid (HBED), a synthetic iron chelator, ameliorated SE-induced changes in chelatable iron, mitochondrial oxidative stress (8-hydroxy-2' deoxyguanosine and glutathione depletion), mitochondrial DNA integrity and hippocampal cell loss. Measurement of brain HBED levels after systemic administration confirmed its penetration in hippocampal mitochondria. These results suggest a role for mitochondrial iron in the pathogenesis of SE-induced brain damage and subcellular iron chelation as a novel therapeutic approach for its management. PMID:18987191

  11. Cultivable diversity of thermophilic arsenite/ferrous-oxidizing microorganisms in hot springs of Taiwan

    NASA Astrophysics Data System (ADS)

    Lu, G.; Lin, Y.; Chang, Y.; Wang, P.; Lin, L.

    2009-12-01

    Elevated levels of arsenic in groundwater and surface water bodies have posed a stringent threat to the deterioration of the water quality for drinking and agriculture purposes around the world. In particular, arsenic liberated from volcanic and sedimentary rocks at high temperatures would be immobilized through adsorption on iron oxide and/or crystallization of iron-bearing minerals downstream at low temperatures. Understanding how microbially-catalytic reactions are involved in the changes of the redox state of arsenic and iron along a flow path would provide important constraints on the arsenic mobility in natural occurrences. The aims of this study were to isolate and characterize thermophilic arsenite- and iron-oxidizing microbes that would facilitate to establish the linkages between microbial distribution and in situ Fe/As cycling processes. Four source waters (LH05, LH08, SYK and MT) from acid-sulfate springs (pH 2-3, 60-97oC) located in the Tatun volcanic area of northern Taiwan were collected and inoculated into media targeting on autotrophic ferrous iron (FC3), arsenite (AC3 ,ACC3, AC7, ACC7), arsenite-resistant hydrogen (AH23), arsenite-resistant hydrogen-sulfur (AH2S3), and arsenite-resistant sulfur oxidations(AS3), and heterotrophic arsenite oxidation(AH3, AH7) at pH 3, and 7 at temperatures of 50, 70 and 80oC. Samples from the Kuantzuling mud springs (KTL) in southwestern Taiwan known with elevated arsenic levels (0.4 ppm) were also collected, inoculated into the heterotrophic medium and incubated at 50, 60, 70 and 80oC. Isolates obtained from KTL were subject to test on the AH7 and ACC7. Two positive enrichments for iron oxidation at 50oC and 70oC were confirmed by the steadily decrease of ferrous iron and increase of precipitates over 4 transfers for samples from the SYK spring. Diverse morphological types of microbes were enriched in all types of arsenite-bearing media at 50oC except for AH23. At 70oC, positive enrichments were found in media which are AH3, AH2S3 and ACC3 from almost all sampling sites. Positive heterotrophic enrichments at 80oC were also obtained from almost all sampling sites. Coccus was the dominant morphotype in this enrichment. One 16S rDNA sequence affiliated with Sulfolobus tokodaii was detected from MT enrichments at 80oC. Alicyclobacillus, Geobacillus, Thermus and Meiothermus related strains were purified from 50oC and 70oC heterotrophic enrichments for samples from LH05 SYK, MT and KTL. Physiological tests indicated that these Alicyclobacillus-related strains are firstly reported to be capable of relying solely on arsenite as the energy source. Hydrogenobaculum-related strains were isolated from AH2S3. Both H2 and S were required for growth. Their 16S rRNA sequences resembled Hydrogenobaculum acidophilum H55 obtained from the Yellowstone National Park of USA. The results expand the current view about the diversity of arsenite-resistant microbes in high temperature environments. More molecular and microscopic works are undergoing to characterize interactions between mineral and microbe in enrichments and natural settings and to place better constraints on the biological effect for Fe/As cycling in hot spring.

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

    PubMed

    Zarzycki, Piotr; Kerisit, Sebastien; Rosso, Kevin

    2011-09-01

    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. By using the COSMO model, we also confirm that a decrease in curvature of the potential energy surface is a manifestation of the dielectric saturation observed in the first solvation layer. 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 and 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. PMID:21696749

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

    SciTech Connect

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

    2011-07-29

    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.

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

    PubMed Central

    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

    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

  15. Structural analysis of metastable pseudobrookite ferrous titanium oxides with neutron diffraction and Mossbauer spectroscopy

    SciTech Connect

    Teller, R.G.; Antonio, M.R. (BP Research, Cleveland, OH (USA)); Grau, A.E.; Gueguin, M. (QIT-Fer et Titane Inc., Sorel, Quebec (Canada)); Kostiner, E. (Univ. of Connecticut, Storrs (USA))

    1990-10-01

    Four synthetic iron titanium oxides with the pseudobrookite (AB{sub 2}O{sub 5}, Cmcm, Z = 4) structure have been prepared and characterized by neutron diffraction and zero-field, natural abundance {sup 57}Fe Mossbauer effect spectroscopy (MES). The combination of the element specificity of MES with the different neutron scattering lengths of Ti and Fe ({minus}0.33 and 0.95 {times} 10{sup {minus}12} cm, respectively) offers a unique opportunity to distinguish between cation distributions on the two (A and B) sites. Two of the samples have been prepared in low temperature experiments (quenched from 1,200{degree}C) and have the stoichiometry FeTi{sub 2}O{sub 5}, and Fe{sub .6}Mg{sub .6}Ti{sub 1.8}O{sub 5}. The third and fourth samples are commercial iron titanium oxides prepared by the reduction of ilmenite ore with carbon above 1,700{degree}C. The stoichiometries of these samples are Mn{sub 0.05}Fe{sub 0.33}Ti{sub 2.52}O{sub 5} and Fe{sub .33}Mg{sub .31}Ti{sub 2.36}O{sub 5}. Results from these experiments indicate that for each of these samples the B site is predominantly (> 65%) occupied by Ti, while the A site contains a mixture of Ti, Fe, and/or Mg. However, only at higher temperatures (> 1,700{degree}C) is the B site devoid of ferrous cations.

  16. Chelating water-soluble polymers for waste minimization

    SciTech Connect

    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

    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.

  17. Chelating ability and biological activity of hesperetin Schiff base.

    PubMed

    Lodyga-Chruscinska, Elzbieta; Symonowicz, Marzena; Sykula, Anna; Bujacz, Anna; Garribba, Eugenio; Rowinska-Zyrek, Magdalena; Oldziej, Stanislaw; Klewicka, Elzbieta; Janicka, Magdalena; Krolewska, Karolina; Cieslak, Marcin; Brodowska, Katarzyna; Chruscinski, Longin

    2015-02-01

    Hydrazone hesperetin Schiff base (HHSB) - N-[(±)-[5,7-dihydroxy-2-(3-hydroxy-4-methoxy-phenyl)chroman-4-ylidene]amino]benzamide has been synthesized and its crystal structure was determined. This compound was used for the formation of Cu(II) complexes in solid state and in solution which were characterized using different spectroscopic methods. The analyses of potentiometric titration curves revealed that monomeric and dimeric complexes of Cu(II) are formed above pH7. The ESI-MS (electrospray ionization-mass spectrometry) spectra confirmed their formation. The EPR and UV-visible spectra evidenced the involvement of oxygen and nitrogen atoms in Cu(II) coordination. Hydrazone hesperetin Schiff base can show keto-enol tautomerism and coordinate Cu(II) in the keto (O(-), N, Oket) and in the enolate form (O(-), N, O(-)enol). The semi-empirical molecular orbital method PM6 and DFT (density functional theory) calculations have revealed that the more stable form of the dimeric complex is that one in which the ligand is present in the enol form. The CuHHSB complex has shown high efficiency in the cleavage of plasmid DNA in aqueous solution, indicating its potential as chemical nuclease. Studies on DNA interactions, antimicrobial and cytotoxic activities have been undertaken to gain more information on the biological significance of HHSB and copper(II)-HHSB chelate species. PMID:25486205

  18. Targeted Cleavage of HIV RRE RNA by Rev-Coupled Transition Metal Chelates

    PubMed Central

    Joyner, Jeff C.; Cowan, J. A.

    2011-01-01

    A series of compounds that target reactive metal-chelates to the HIV-1 Rev Response Element (RRE) mRNA have been synthesized. Dissociation constants and chemical reactivity toward HIV RRE RNA have been determined and evaluated in terms of reduction potential, coordination unsaturation, and overall charge associated with the metal-chelate-rev complex. Ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), diethylenetriaminepentaacetic acid (DTPA), and 1,4,7,10-tetraazacyclo-dodecane-1,4,7,10-tetraacetic acid (DOTA) were linked to a lysine sidechain of a Rev-derived peptide by either EDC/NHS or isothiocyanate coupling. The resulting chelate-Rev (EDTA-Rev, DTPA-Rev, NTA-Rev, and DOTA-Rev) conjugates were used to form coordination complexes with Fe2+, Co2+, Ni2+, and Cu2+ such that the arginine-rich Rev peptide could mediate localization of the metal-chelates to the Rev peptide’s high-affinity mRNA binding partner, RRE stem loop IIB. Metal complexes of the extended peptides GGH-Rev and KGHK-Rev, which also contain N-terminal peptidic chelators (ATCUN motifs), were studied for comparison. A fluorescence titration assay revealed high affinity RRE RNA binding by all 22 metal-chelate-Rev species, with KD values ranging from ~ 0.2 – 16 nM, indicating little to no loss of RNA affinity due to the coupling of the metal-chelates to the Rev peptide. Dissociation constants for binding at a previously unobserved low-affinity site are also reported. Rates of RNA modification by each metal-chelate-Rev species were determined and varied from ~ 0.28 – 4.9 nM/min, but were optimal for Cu2+-NTA-Rev. Metal-chelate reduction potentials were determined and varied from ?228 to +1111 mV vs. NHE under similar solution conditions, allowing direct comparison of reactivity with redox thermodynamics. Optimal activity was observed when the reduction potential for the metal center was poised between that of the two principal coreagents for metal-promoted formation of reactive oxygen species: E°ascorbate/ascorbyl radical = ?66 mV; E°H2O2/hydroxyl radical = 380 mV. Given the variety of oxidative activities of these metal-complexes and their high-affinity binding to the targeted RRE mRNA following coupling to the Rev peptide, this class of metal-chelate-Rev derivatives constitutes a promising step toward development of multiple-turnover reagents for selective eradication of HIV-1 Rev response element mRNA. PMID:21585196

  19. Dry cereals fortified with electrolytic iron or ferrous fumarate are equally effective in breast-fed infants.

    PubMed

    Ziegler, Ekhard E; Fomon, Samuel J; Nelson, Steven E; Jeter, Janice M; Theuer, Richard C

    2011-02-01

    Precooked, instant (dry) infant cereals in the US are fortified with electrolytic iron, a source of low reactivity and suspected low bioavailability. Iron from ferrous fumarate is presumed to be more available. In this study, we compared a dry infant rice cereal (Cereal L) fortified with electrolytic iron (54.5 mg iron/100 g cereal) to a similar cereal (Cereal M) fortified with ferrous fumarate (52.2 mg Fe/100 g) for efficacy in maintaining iron status and preventing iron deficiency (ID) in breast-fed infants. Ascorbic acid was included in both cereals. In this prospective, randomized double-blind trial, exclusively breast-fed infants were enrolled at 1 mo and iron status was determined periodically. At 4 mo, 3 infants had ID anemia and were excluded. Ninety-five infants were randomized at 4 mo, and 69 (36 Cereal L, 33 Cereal M) completed the intervention at 9 mo. From 4 to 9 mo, they consumed daily one of the study cereals. With each cereal, 2 infants had mild ID, a prevalence of 4.2%, but no infant developed ID anemia. There were no differences in iron status between study groups. Iron intake from the study cereals was (mean ± SD) 1.21 ± 0.31 mg?kg(-1)?d(-1) from Cereal L and 1.07 ± 0.40 mg?kg(-1)?d(-1) from Cereal M. Eleven infants had low birth iron endowment (plasma ferritin < 55 ?g/L at 2 mo) and 54% of these infants had ID with or without anemia by 4 mo. We conclude that electrolytic iron and ferrous fumarate were equally efficacious as fortificants of this infant cereal. PMID:21178077

  20. Major Role for FeoB in Campylobacter jejuni Ferrous Iron Acquisition, Gut Colonization, and Intracellular Survival

    PubMed Central

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

    2006-01-01

    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

  1. Pilot field-verification studies of the sodium sulfide/ferrous sulfate treatment process. Final report, September 1987-May 1988

    SciTech Connect

    Wiloff, P.M.; Suciu, D.F.; Prescott, D.S.; Schober, R.K.; Loyd, F.S.

    1988-09-01

    In previous project, jar and dynamic testing showed that the sodium sulfide/ferrous sulfate process was a viable method for reducing hexavalent chromium and removing heavy metals from the Tinker AFB industrial wastewater with significant decrease in sludge production and treatment costs. In this phase, pilot-plant field verification studies were conducted to evaluate the chemical and physical parameters of the chromium reduction process, the precipitation and clarification process, and the activated-sludge system. Sludge production was evaluated and compared to the sulfuric acid/sulfur dioxide/lime process.

  2. The relation of fO?, ferric-ferrous ratio (R), and physical properties of four natural clinoamphiboles 

    E-print Network

    Clowe, Celia Ann

    1987-01-01

    ). Iron can be accommodated in four unique structural sites within amphiboles, M(4), M(2), M( I), M(3). The Fe3+/Fe2+, as well as the site-occupancy of iron, varies in response to the environment of formation. At present, the interrelationship between... to increased oxygen fugaci ty. Fe-poor amphiboles exhibit a greater stability, associated with a higher temper- ature of dehydroxylation. Ferrous i ron-rich amphi boles exhibit a greater variation in physical properties after heat-treating. (4) Powder X...

  3. Enhancement of Phloem exudation from cut petioles by chelating agents.

    PubMed

    King, R W; Zeevaart, J A

    1974-01-01

    The photosynthetic assimilates in leaves of Perilla crispa attached to the plant were labeled by treating the leaves with (14)CO(2). When subsequently detached, these leaves exuded a negligible amount of radioactivity from the cut petiole into water. Ethylenediaminetetraacetate (EDTA), citric acid, and ethyleneglycol-bis (beta-aminoethyl ether) N,N'-tetraacetate greatly increased exudation of labeled assimilates into a solution bathing the petioles. The optimal concentration of EDTA was 20 mm, and maximal exudation took place between 2 and 4 hours after excision. Up to 22% of the radioactivity fixed in the leaf was exuded into an EDTA solution as compared to an export of 38% from attached leaves. The amount of radioactivity in the exudate was much reduced at low temperature. Presence of EDTA was required in the collecting solution for only 1 to 2 hours; upon transfer to water, exudation continued as in continuous presence of EDTA. Ca(2+) completely inhibited the effect of EDTA.Anatomical studies indicated that callose formation on the sieve plates near the cut surface of the petioles was less in leaves on EDTA than on water.More than 95% of the radioactivity exuded by detached leaves was present in the sugars verbascose, stachyose, raffinose, and sucrose, which are translocated in the phloem of Perilla. Labeled glucose, fructose, and galactinol were detected in the leaf blade and petiole, but not in exudates.The addition of EDTA to a solution bathing the petiole of detached leaves of Chenopodium rubrum and Pharbitis nil also increased the exudation of labeled assimilates. In these two species, label appeared only in a compound that cochromatographed with sucrose.It is concluded that the radioactive products in the solution are actually exuded by the phloem. Possibly EDTA chelates Ca(2+) that otherwise participates in the reactions that seal cut phloem. PMID:16658661

  4. Clinically available iron chelators induce neuroprotection in the 6-OHDA model of Parkinson’s disease after peripheral administration

    Microsoft Academic Search

    David T. Dexter; Sarah A. Statton; Charlotte Whitmore; Wolfhardt Freinbichler; Peter Weinberger; Keith F. Tipton; Laura Della Corte; Roberta J. Ward; Robert R. Crichton

    2011-01-01

    The iron content of the substantia nigra pars compacta increases in the brains of Parkinson’s disease patients. Hence, its\\u000a removal by iron chelators may retard the progression of the disease. However, information on the ability of clinically available\\u000a iron chelators to cross the blood brain barrier and be neuroprotective is limited. In this present study three iron chelators,\\u000a which are

  5. Thumbnail Sketches: EDTA-Type Chelating Agents in Everyday Consumer Products: Some Medicinal and Personal Care Products.

    ERIC Educational Resources Information Center

    Hart, J. Roger

    1984-01-01

    Discusses various ethylenediaminetetraacetate (EDTA)-type chelating agents found in ophthalmic products, personal care products, and disinfectants. Also discusses the properties and action of these EDTA agents. (JN)

  6. Targeted catalytic inactivation of angiotensin converting enzyme by lisinopril-coupled transition-metal chelates.

    PubMed

    Joyner, Jeff C; Hocharoen, Lalintip; Cowan, J A

    2012-02-22

    A series of compounds that target reactive transition-metal chelates to somatic angiotensin converting enzyme (sACE-1) have been synthesized. Half-maximal inhibitory concentrations (IC(50)) and rate constants for both inactivation and cleavage of full-length sACE-1 have been determined and evaluated in terms of metal chelate size, charge, reduction potential, coordination unsaturation, and coreactant selectivity. Ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA), and tripeptide GGH were linked to the lysine side chain of lisinopril by 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide hydrochloride/N-hydroxysuccinimide coupling. The resulting amide-linked chelate-lisinopril (EDTA-lisinopril, NTA-lisinopril, DOTA-lisinopril, and GGH-lisinopril) conjugates were used to form coordination complexes with iron, cobalt, nickel, and copper, such that lisinopril could mediate localization of the reactive metal chelates to sACE-1. ACE activity was assayed by monitoring cleavage of the fluorogenic substrate Mca-RPPGFSAFK(Dnp)-OH, a derivative of bradykinin, following preincubation with metal chelate-lisinopril compounds. Concentration-dependent inhibition of sACE-1 by metal chelate-lisinopril complexes revealed IC(50) values ranging from 44 to 4500 nM for Ni-NTA-lisinopril and Ni-DOTA-lisinopril, respectively, versus 1.9 nM for lisinopril. Stronger inhibition was correlated with smaller size and lower negative charge of the attached metal chelates. Time-dependent inactivation of sACE-1 by metal chelate-lisinopril complexes revealed a remarkable range of catalytic activities, with second-order rate constants as high as 150,000 M(-1) min(-1) (Cu-GGH-lisinopril), while catalyst-mediated cleavage of sACE-1 typically occurred at much lower rates, indicating that inactivation arose primarily from side chain modification. Optimal inactivation of sACE-1 was observed when the reduction potential for the metal center was poised near 1000 mV, reflecting the difficulty of protein oxidation. This class of metal chelate-lisinopril complexes possesses a range of high-affinity binding to ACE, introduces the advantage of irreversible catalytic turnover, and marks an important step toward the development of multiple-turnover drugs for selective inactivation of sACE-1. PMID:22200082

  7. Assessment of iron chelates efficiency for photo-Fenton at neutral pH.

    PubMed

    De Luca, Antonella; Dantas, Renato F; Esplugas, Santiago

    2014-09-15

    In this study, homogeneous photo-Fenton like at neutral pH was applied to remove sulfamethoxazole from water. The process was performed using different chelating agents in order to solubilize iron in a neutral water solution. The chelating agents tested were: ethylenediaminetetraacetic acid (EDTA); nitrilotriacetic acid (NTA); oxalic acid (OA) and tartaric acid (TA). The iron leaching was monitored over reaction time to evaluate the chelates stability and their resistance to HO· and UV-A radiation. Chelates of EDTA and NTA presented more stability than OA and TA, which also confirmed their higher efficiency. Total Organic Carbon (TOC) analyses were also performed to evaluate the contribution in terms of solution contamination related to the use of chelating agents. The better properties of biodegradability in respect of EDTA combined with better efficiency in terms of microcontaminant removal and the smallest TOC contribution indicate that NTA could represent a useful option to perform photo-Fenton processes at neutral pH. PMID:24930010

  8. Preparation of amine group-containing chelating fiber for thorough removal of mercury ions.

    PubMed

    Ma, Nianfang; Yang, Ying; Chen, Shuixia; Zhang, Qikun

    2009-11-15

    An aminated chelating fiber (AF) with high adsorption capacity for mercury ions was prepared by grafting copolymerization of acrylonitrile onto polypropylene fiber, followed by aminating with chelating molecule diethylenetriamine. Effects of reaction conditions such as temperature, reaction time, bath ratio and dosage of catalyst on the grafting yield were studied. Chemical structure, tensile strength and thermal stability of AF were characterized. The adsorption performances for mercury were evaluated by batch adsorption experiments and kinetic experiments. The results show that AF is effective for the removal of mercury over a wide range of pH. The chelating fiber also shows much higher adsorption capacities for mercury, the equilibrium adsorption amount could be as high as 657.9 mg/g for mercury. The high adsorption capacity of Hg(2+) on AF is resulted from the strong chelating interaction between amine groups and mercury ions. Two amine groups coordinate with one mercury ion could be speculated from the adsorption capacity and amine group content on AF. The kinetic adsorption results indicate that the adsorption rates of AF for mercury are very rapid. Furthermore, the residual concentration was less than 1 microg/L with feed concentration of mercury below 1mg/L, which can meet the criterion of drinking water, which indicates that the chelating fiber prepared in this study could be applied to low-level Hg contaminated drinking water purification. PMID:19559522

  9. Pharmacological properties of orally available, amphipathic polyaminocarboxylic acid chelators for actinide decorporation.

    PubMed

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

    2010-09-01

    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 plutonium and americium. The synthesis, efficacy, binding affinities, and some initial pharmacokinetics properties of amphipathic TT chelators are reviewed. C-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 Pu 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

  10. Synthesis, characterization and cyclic voltammetric study of copper(II) and nickel(II) polymer chelates.

    PubMed

    Azmeera, Venkanna; Rastogi, Pankaj Kumar; Adhikary, Pubali; Ganesan, Vellaichamy; Krishnamoorthi, S

    2014-09-22

    Graft copolymers based on dextran (Dx) and 2-acrylamido-2-methyl-1-propane sulphonic acid (AMPS) were synthesized by free radical initiated solution polymerization technique using ceric ammonium nitrate as initiator. These graft copolymers were used to prepare Cu(II) and Ni(II) chelates by reactions with Cu(II) and Ni(II) metal ions respectively. Graft copolymer and metal chelates were characterized by elemental analysis, intrinsic viscosity, FT-IR, scanning electron microscopy (SEM), atomic force microscopy (AFM), thermogravimetric analysis (TGA) and powder X-ray diffraction (XRD). Elemental analysis, intrinsic viscosity and FT-IR studies revealed the incorporation of metal ions to form metal chelates. SEM studies showed the change in morphology due to metal incorporation. From AFM studies it was observed that there was increase in Root mean square (RMS) roughness values in case of metal complexes. Metal chelates were observed to be thermally more stable than graft copolymer from TGA. UV-vis spectroscopy study revealed increase in absorbance values and cyclic voltammetric (CV) studies showed more than tenfold increase in redox current due to formation of Cu(II) and Ni(II) metal chelates. The binding constants of each complex determined by using UV-visible spectroscopy revealed that Cu(II) has more binding ability than Ni(II). PMID:24906771

  11. Identifying Chelators for Metalloprotein Inhibitors Using a Fragment-Based Approach

    PubMed Central

    Jacobsen, Jennifer A.; Fullagar, Jessica; Miller, Melissa T.; Cohen, Seth M.

    2011-01-01

    Fragment-based lead design (FBLD) has been used to identify new metal-binding groups for metalloenzyme inhibitors. When screened at 1 mM, a chelator fragment library (CFL-1.1) of 96 compounds produced hit rates ranging from 29–43% for five matrix metalloproteases (MMPs), 24% for anthrax lethal factor (LF), 49% for 5-lipoxygenase (5-LO), and 60% for tyrosinase (TY). The ligand efficiencies (LE) of the fragment hits are excellent, in the range of 0.4–0.8 kcal/mol. The MMP enzymes all generally elicit the same chelators as hits from CFL-1.1; however, the chelator fragments that inhibit structurally unrelated metalloenzymes (LF, 5-LO, TY) vary considerably. To develop more advanced hits, one hit from CFL-1.1, 8-hydroxyquinoline, was elaborated at four different positions around the ring system to generate new fragments. 8-Hydroxyquinoline fragments substituted at either the 5- or 7-positions gave potent hits against MMP-2, with IC50 values in the low micromolar range. The 8-hydroxyquinoline represents a promising, new chelator scaffold for the development of MMP inhibitors that was discovered by use of a metalloprotein-focused chelator fragment library. PMID:21189019

  12. Arsenic induced oxidative stress and the role of antioxidant supplementation during chelation: a review.

    PubMed

    Flora, S J S; Bhadauria, Smrati; Kannan, G M; Singh, Nutan

    2007-04-01

    Arsenic is a naturally occurring metalloid, ubiquitously present in the environment in both organic and inorganic forms. Arsenic contamination of groundwater in the West Bengal basin in India is unfolding as one of the worst natural geoenvironmental disaster to date. Chronic exposure of humans to high concentration of arsenic in drinking water is associated with skin lesions, peripheral vascular disease, hypertension, Blackfoot disease and high risk of cancer The underlying mechanism of toxicity includes the interaction with the sulphydryl groups and the generation of reactive oxygen species leading to oxidative stress. Chelation therapy with chelating agents like British Anti Lewisite (BAL), sodium 2,3-dimercaptopropane 1-sulfonate (DMPS), meso 2,3 dimercaptosuccinic acid (DMSA) etc., is considered to be the best known treatment against arsenic poisoning. The treatment with these chelating agents however is compromised with certain serious drawbacks/side effects. The studies show that supplementation of antioxidants along with a chelating agent prove to be a better treatment regimen. This review attempts to provide the readers with a comprehensive account of recent developments in the research on arsenic poisoning particularly the role of oxidative stress/free radicals in the toxic manifestation, an update about the recent strategies for the treatment with chelating agents and a possible beneficial role of antioxidants supplementation to achieve the optimum effects. PMID:17929749

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

    PubMed Central

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

    2010-01-01

    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

  14. Immobilization of beta-galactosidase on metal-chelate-substituted gels.

    PubMed

    Brena, B M; Rydén, L G; Porath, J

    1994-04-01

    The use of copper, zinc, iron, nickel and calcium in three different chelating gels was investigated for preparing immobilized beta-galactosidase. The chelated ligands [Cu(2+)-iminodiacetate (IDA), Cu(2+)-Tris(carboxymethyl)ethylenediamine (TED), Ni(2+)-IDA and Fe(3+)-IDA] absorbed the protein so strongly that it can be considered a true immobilization. The obtained enzyme derivatives were investigated with regard to activity and stability. Enzymic activity was highly preserved in general for the TED derivates (90% when compared with that for Cu(2+)-TED). The immobilized Ni2+ derivatives were more stable to high temperature and to storage than the Cu2+ derivatives. Temperature-stability of the immobilized enzyme was very much improved by adding a strong metal-chelating gel such as carboxymethylated tetraethylenepentamine-agarose. The gel could be re-used and reloaded after elution with chelator. beta-Galactosidase from Escherichia coli was purified using immobilized-metal-ion-chelate chromatography (i.m.a.c.). The potential use of beta-galactosidase immobilized on i.m.a.c. gels for technical purposes is discussed. PMID:8192868

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

    PubMed

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

    2014-09-01

    Oxidative stress is a common denominator of numerous cardiovascular disorders. Free cellular iron catalyzes the 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, the aroylhydrazone prochelators BHAPI and BSIH-PD provided significant cytoprotection and displayed lower toxicity after 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 the aroylhydrazone prochelator BSIH. BSIH efficiently protected both H9c2 rat cardiomyoblast-derived cells and isolated primary rat cardiomyocytes against hydrogen peroxide-induced mitochondrial and lysosomal dysregulation and cell death. At the same time, BSIH was nontoxic at concentrations up to its solubility limit (600 ?M) and in 72-h 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

  16. Comparative effects of chelating drugs on trace metal and biochemical alterations in the rat

    SciTech Connect

    Misra, M.; Athar, M.; Hasan, S.K.; Srivastava, R.C.

    1988-08-01

    Chelation therapy is the most successful modality for the management of heavy metal poisoning. The success of these drugs stem from their multidentate polyfunctional chelating behavior. The therapeutic mechanism for chelating drugs involves their interaction with toxic metals leading to their rapid excretion from the body. However, because of their indiscriminate affinity for various metal ions, the potential interactions between these drugs and endogenous trace metals is of concern. It was, therefore, of importance to define new chelating drugs which in addition to being effective as an antidote in metal poisoning may possess low undesirable toxicity. In the present communication the authors compare the acute effect of Cyclam with those of other conventional chelating drugs namely, triethylenetetramine (TETA), reduced glutathione (GSH), ethylenediamine tetraacetic acid (EDTA), cyclohexanediamine tetraacetic acid (CDTA), diethylene triamine pentaacetic acid (DTPA) and hydroxyethylenediamine triacetic acid (HEDTA) on (i) serum levels of Cu, Zn, lactate dehydrogenase (LDH), glutamyloxaloacetic transaminase (GOT) and ceruloplasmin (CP); (ii) hepatic and renal levels of Cu, Mn, Zn and Fe and (iii) hepatic and renal levels of GSH, glutathione-S-transferase (GST) and phosphoglucomutase (PGM) at various time intervals (16, 24 and 72 hrs) after their administration to rats.

  17. Mechanism and efficiency of cell death of type II photosensitizers: effect of zinc chelation.

    PubMed

    Pavani, Christiane; Iamamoto, Yassuko; Baptista, Maurício S

    2012-01-01

    A series of meso-substituted tetra-cationic porphyrins, which have methyl and octyl substituents, was studied in order to understand the effect of zinc chelation and photosensitizer subcellular localization in the mechanism of cell death. Zinc chelation does not change the photophysical properties of the photosensitizers (all molecules studied are type II photosensitizers) but affects considerably the interaction of the porphyrins with membranes, reducing mitochondrial accumulation. The total amount of intracellular reactive species induced by treating cells with photosensitizer and light is similar for zinc-chelated and free-base porphyrins that have the same alkyl substituent. Zinc-chelated porphyrins, which are poorly accumulated in mitochondria, show higher efficiency of cell death with features of apoptosis (higher MTT response compared with trypan blue staining, specific acridine orange/ethidium bromide staining, loss of mitochondrial transmembrane potential, stronger cytochrome c release and larger sub-G1 cell population), whereas nonchelated porphyrins, which are considerably more concentrated in mitochondria, triggered mainly necrotic cell death. We hypothesized that zinc-chelation protects the photoinduced properties of the porphyrins in the mitochondrial environment. PMID:22283143

  18. Nitrate-dependent anaerobic ferrous oxidation (NAFO) by denitrifying bacteria: a perspective autotrophic nitrogen pollution control technology.

    PubMed

    Zhang, Meng; Zheng, Ping; Wang, Ru; Li, Wei; Lu, Huifeng; Zhang, Jiqiang

    2014-12-01

    The nitrate-dependent anaerobic ferrous oxidation (NAFO) is an important discovery in the fields of microbiology and geology, which is a valuable biological reaction since it can convert nitrate into nitrogen gas, removing nitrogen from wastewater. The research on NAFO can promote the development of novel autotrophic biotechnologies for nitrogen pollution control and get a deep insight into the biogeochemical cycles. In this work, batch experiments were conducted with denitrifying bacteria as biocatalyst to investigate the performance of nitrogen removal by NAFO. The results showed that the denitrifying bacteria were capable of chemolithotrophic denitrification with ferrous salt as electron donor, namely NAFO. And the maximum nitrate conversion rates (qmax) reached 57.89 mg (g VSS d)?1, which was the rate-limiting step in NAFO. Fe/N ratio, temperature and initial pH had significant influences on nitrogen removal by NAFO process, and their optimal values were 2.0 °C, 30.15 °C and 8.0 °C, respectively. PMID:25461924

  19. Photoreduction of carbon dioxide by aqueous ferrous ion: An alternative to the strongly reducing atmosphere for the chemical origin of life

    PubMed Central

    Borowska, Zofia; Mauzerall, David

    1988-01-01

    We have shown that ferrous ion at neutral pH photoreduces water to hydrogen with a high quantum yield on excitation with near-ultraviolet light. This simple system also efficiently reduces carbon dioxide (bicarbonate ions) to formaldehyde. Overall, these reactions offer a solution to a dilemma confronting the standard or Oparin-Urey model of the origin of life. If carbon dioxide was the main form of carbon on the primitive earth, the ferrous photoreaction would have provided the reduced carbon necessary to form amino acids and other biogenetic molecules. We believe this system may have been the progenitor to the biological photosynthetic systems. PMID:16593977

  20. Synthesis of a new chelating gel: removal of Ca2+ ions from parvalbumin.

    PubMed

    Haner, M; Henzl, M T; Raissouni, B; Birnbaum, E R

    1984-04-01

    The synthesis of a chelating gel which contains the effective metal chelating agent ethylenediaminetetraacetic acid covalently linked to amino-agarose is described. This gel is shown to be a rapid and extremely effective material for the removal of tightly bound, but labile metal ions from proteins without introducing contaminants into the biological system. The synthesis involves the formation of an amide linkage between the dangling carboxylate arm of the [Co(EDTA)Cl]2-complex and amino-agarose using a standard carbodiimide coupling reaction. The chelating gel is shown to remove approximately 98.5% of the calcium from fully bound Ca2-parvalbumin and over 99% of the europium from Eu2-parvalbumin. PMID:6428271

  1. Oxidation of aqueous sulfur dioxide. 3. The effects of chelating agents and phenolic antioxidants

    SciTech Connect

    Lim, P.K.; Huss, A. Jr.; Eckert, C.A.

    1982-10-14

    The inhibiting effects of chelating agents (1,10-phenanthroline and EDTA) and phenolic antioxidants (phenol, hydroquinone, resorcinol, pyrocatechol, phloroglucinol, and pyrogallol) on the catalyzed oxidations of low- and high-pH aqueous S(IV) solutions were investigated. Both the low-pH Mn(II)- and Fe(II)-catalyzed reactions were inhibited by phenolic antioxidants, with the effect on the Mn(II)-catalyzed reaction being much more pronounced. The chelating agents, on the other hand, had a far greater inhibiting influence on the Fe(II)-catalyzed reaction. The high-pH Cu(II)-catalyzed reaction was markedly inhibited by both chelating agents and antioxidants. The results support our previous conclusion that the previously accepted uncatalyzed oxidations of S(IV) were in fact primarily trace-metal catalyzed. 7 figures.

  2. Analysis of Supercritical-Extracted Chelated Metal Ions From Mixed Organic-Inorganic Samples

    NASA Technical Reports Server (NTRS)

    Sinha, Mahadeva P. (Inventor)

    1996-01-01

    Organic and inorganic contaminants of an environmental sample are analyzed by the same GC-MS instrument by adding an oxidizing agent to the sample to oxidize metal or metal compounds to form metal ions. The metal ions are converted to chelate complexes and the chelate complexes are extracted into a supercritical fluid such as CO2. The metal chelate extract after flowing through a restrictor tube is directly injected into the ionization chamber of a mass spectrometer, preferably containing a refractory metal filament such as rhenium to fragment the complex to release metal ions which are detected. This provides a fast, economical method for the analysis of metal contaminants in a sample and can be automated. An organic extract of the sample in conventional or supercritical fluid solvents can be detected in the same mass spectrometer, preferably after separation in a supercritical fluid chromatograph.

  3. Iron chelation therapy in transfusion-dependent thalassemia patients: current strategies and future directions

    PubMed Central

    Saliba, Antoine N; Harb, Afif R; Taher, Ali T

    2015-01-01

    Transfusional iron overload is a major target in the care of patients with transfusion-dependent thalassemia (TDT) and other refractory anemias. Iron accumulates in the liver, heart, and endocrine organs leading to a wide array of complications. In this review, we summarize the characteristics of the approved iron chelators, deferoxamine, deferiprone, and deferasirox, and the evidence behind the use of each, as monotherapy or as part of combination therapy. We also review the different guidelines on iron chelation in TDT. This review also discusses future prospects and directions in the treatment of transfusional iron overload in TDT whether through innovation in chelation or other therapies, such as novel agents that improve transfusion dependence.

  4. The synthesis and characterization of new iron coordination complexes utilizing an asymmetric coordinating chelate ligand

    SciTech Connect

    Watkins, B.E.; Satcher, J.H.

    1995-07-01

    A binuclear, unsymmetric coordinating ligand that is an effective metal chelator has been designed and synthesized. The new ligand has been shown to react readily with iron(II)/(III) forming a variety of coordination complexes. The binuclear complexes are of significant interest since they represent proof-of-principle for the development of coordinatively asymmetric, binuclear metal chelate compounds. Although this structural type of chelator now appears to be common in biological systems, it has not been previously described for inorganic coordination chemistry. The isolation of oxidation products will be helpful in establishing reaction mechanism(s) of these complexes with molecular oxygen. It is expected that this ligand and derivatives of it will play an important role in the development of bioinorganic complexes that aim to mimic enzyme active sites that function by substrate interaction at only one metal site of a multimetal active site.

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

    Microsoft Academic Search

    G. J. Kontoghiorghes; E. D. Weinberg

    1995-01-01

    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

  6. Chelator-induced phytoextraction of zinc and copper by rice seedlings.

    PubMed

    Yu, Xiao-Zhang; Wang, Dun-Qiu; Zhang, Xue-Hong

    2014-05-01

    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

  7. Antimicrobial action of chelating agents: repercussions on the microorganism development, virulence and pathogenesis.

    PubMed

    Santos, A L S; Sodre, C L; Valle, R S; Silva, B A; Abi-Chacra, E A; Silva, L V; Souza-Goncalves, A L; Sangenito, L S; Goncalves, D S; Souza, L O P; Palmeira, V F; d'Avila-Levy, C M; Kneipp, L F; Kellett, A; McCann, M; Branquinha, M H

    2012-01-01

    Infections caused by resistant microorganisms often fail to respond to conventional therapy, resulting in prolonged illness, increased treatment costs and greater risk of death. Consequently, the development of novel antimicrobial drugs is becoming more demanding every day since the existing drugs either have too many side-effects or they tend to lose effectiveness due to the selection of resistant strains. In view of these facts, a number of new strategies to obstruct vital biological processes of a microbial cell have emerged; one of these is focused on the use of metal-chelating agents, which are able to selectively disturb the essential metal metabolism of the microorganism by interfering with metal acquisition and bioavailability for crucial reactions. The chelation activity is able to inhibit the biological role of metal-dependent proteins (e.g., metalloproteases and transcription factors), disturbing the microbial cell homeostasis and culminating in the blockage of microbial nutrition, growth and development, cellular differentiation, adhesion to biotic (e.g., extracellular matrix components, cell and/or tissue) and abiotic (e.g., plastic, silicone and acrylic) structures as well as controlling the in vivo infection progression. Interestingly, chelating agents also potentiate the activity of classical antimicrobial compounds. The differences between the microorganism and host in terms of the behavior displayed in the presence of chelating agents could provide exploitable targets for the development of an effective chemotherapy for these diseases. Consequently, metal chelators represent a novel group of antimicrobial agents with potential therapeutic applications. This review will focus on the anti-fungal and anti-protozoan action of the most common chelating agents, deciphering and discussing their mode of action. PMID:22455582

  8. New synthetic approach and iron chelating studies of 1-alkyl-2-methyl-3-hydroxypyrid-4-ones.

    PubMed

    Kontoghiorghes, G J; Sheppard, L; Chambers, S

    1987-10-01

    The major diseases of iron metabolism are iron deficiency anaemia, which could be treated using Fe2+ or Fe3+ salt supplements, and iron overload, which could arise either from an increased gastrointestinal absorption of iron or from recurrent blood transfusions. While the former form of iron overload could be treated by phlebotomy the latter requires the use of a chelator. Desferrioxamine is the only clinically available chelator for the treatment of iron overload but its use worldwide is limited because it is expensive and orally inactive. Several alpha-ketohydroxy heteroaromatic chelators have been synthesised and tested for their iron binding properties at physiological pH. The synthetic route involves the benzylation of the hydroxyl group of maltol using benzyl chloride, the conversion of the benzylated maltol to the 1-alkyl benzylated pyridine derivative by introducing the corresponding alkylamine in alkaline conditions and the cleavage of the benzyl group in acid to form the 1-alkyl-2-methyl-3-hydroxypyrid-4-one. All the chelators are water soluble and stable at a wide range of pH, forming stable, water soluble, coloured iron complexes with a molar ratio of approximately 3 chelator: 1 iron at pH 7.4 and lower molar ratio of chelators to iron complexes at acidic pH. When the 1-methyl, 1-ethyl and 1-propyl, -2-methyl-3-hydroxypyrid-4-ones were mixed at pH 7.4 with transferrin, ferritin and haemosiderin substantial amounts of iron were released.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:3435580

  9. The use of o-mercaptobenzoic acid as a chelating agent 

    E-print Network

    Moody, Thomas Ned

    1966-01-01

    THE USE OF o-MERCAPTOBENZOIC ACID AS A CHELATING AGENT A Thesis By THOMAS NED MOODY Submitted to the Graduate College of the Texas A&M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE August 1966 Ma...]or Sub)act: Chemistry THE USE OF o-MERCAPTOBENZOIC ACID AS A CHELATING AGENT A Thesis By THOMAS NED MOODY Approved as to style and content by: (Chai an of ommi ee (H ad fg partment) (Member) ( mber (Member) (Member) (Member) August 1966...

  10. Hyperbranched chelating polymers for the polymer-assisted ultrafiltration of boric acid

    SciTech Connect

    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

    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.

  11. A novel bifunctional maleimido CHX-A'' chelator for conjugation to thiol-containing biomolecules.

    PubMed

    Xu, Heng; Baidoo, Kwamena E; Wong, Karen J; Brechbiel, Martin W

    2008-04-15

    A novel bifunctional maleimido CHX-A'' DTPA chelator 5 was developed and conjugated to the monoclonal antibody trastuzumab (Herceptin) and subsequently radiolabeled with (111)In. The resulting (111)In labeled immunoconjugate 2 was demonstrated to bind to SKOV-3 ovarian cancer cells comparably to an isothiocyanato CHX-A'' DTPA modified native trastuzumab, 1. Through efficient thiol-maleimide chemistry, antibodies, peptides or other targeting vectors can now be modified with an established radioactive metal chelating agent CHX-A'' DTPA for imaging and/or therapies of cancer. PMID:18359632

  12. Recent advances in chelator design and labelling methodology for (68) Ga radiopharmaceuticals.

    PubMed

    Burke, Benjamin P; Clemente, Gonçalo S; Archibald, Stephen J

    2014-04-01

    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

  13. Vanadate enhancement of the oxidation of NADH by O2-: effects of phosphate and chelating agents.

    PubMed

    Darr, D; Fridovich, I

    1985-11-15

    Vanadate markedly stimulates the oxidation of NADH by O2-. Both phosphate and Tris are inhibitory, but phosphate diminishes the greater inhibitory effect of Tris and thus gives the appearance of stimulating when added to Tris-buffered reaction mixtures. Chelating agents moderately increased the oxidation of NADH but eliminated the much greater catalytic effect of vanadate. Desferal was the most effective of the chelating agents, and could be used to titrate vanadate spectrophotometrically or in terms of the diminution of its catalytic activity. This permitted the demonstration that metavanadate or orthovanadate could form 1:1 complexes with desferal and that orthovanadate was the catalytically active species. PMID:3851646

  14. Metabolic and pharmacokinetic evaluation of a Novel 3-hydroxypyridinone iron chelator, CP502, in the rat

    Microsoft Academic Search

    Jasmina Novakovic; Angelo Tesoro; Jake J. Thiessen; Michael Spino

    2004-01-01

    Summary  A recently synthesized 3-hydroxypyridinone derivative with an amido function at the 2-position, CP502 (1, 6-dimethyl-3-hydroxy-4-(1H)-pyridinone-2-carboxy-(N-methyl)-amide\\u000a hydrochloride), exhibited high in vitro iron chelating potency (pFe3+=21.7). It was targeted as a new iron-chelating candidate for further development in early pre-clinical testing. To evaluate\\u000a its pharmacokinetics, including oral bioavailability, metabolic and disappearance profiles, studies were conducted in Sprague\\u000a Dawley male rats. A single

  15. The role of labile iron in kidney disease and treatment with chelation.

    PubMed

    Shah, Sudhir V; Rajapurkar, Mohan M

    2009-01-01

    There are two major forms of kidney disease: acute renal failure [also referred to as acute kidney injury (AKI)] and chronic kidney disease (CKD). Acute renal failure is an abrupt loss of kidney function within 48 h, whereas CKD is a loss of kidney function greater than 3 months. There is a large amount of experimental evidence for an increase of labile iron in a wide variety of models of kidney disease. Additionally, iron chelators provide protection, indicating an important role of labile iron in these diseases. These observations suggest that iron chelators may provide a new modality of prevention and treatment of kidney disease. PMID:19821781

  16. Metal chelates of N,N'-dihydroxyethyl-N,N'-ethylenediaminedisuccinic acid and selected metal ions

    E-print Network

    Hampton, Joan Martiner

    1972-01-01

    Ijniverslty Directed by: Arthur E. Martell A quantitative study of the chelating tendencies of N, N'-dihydroxyethyl-N, N'-ethylenediaminedisuccinic acid with a series of metal ions was carried out in aqueous so- lution. Ca(II), Mg(II), Mn(II), Pb(II), Co(II...), Cu(II), Zn(II), Ni (I I), and Fe(I II) are the metal ions employed in this study. Metal chelate formation constants were deter- mined from potentiometric equilibrium data obtained at 25' C and at an ionic strength of 0. 10 (0. 10 M KN03). Metal...

  17. Reactivity and molecular modeling of new solvatochromic mixed-ligand copper(II) chelates of 2-acetylbutyrolactone and dinitrogen bases.

    PubMed

    Taha, A; Adly, Omima M I; Shebl, Magdy

    2015-04-01

    A new series of solvatochromic mononuclear mixed ligand chelates with the general formula: Cu(AcBL)(L)X; where AcBL=2-acetylbutyrolactonate, L=N,N,N',N'-tetramethylethylenediamine (Me4en), N,N,N',N'-tetramethylpropylene diamine (Me4pn), 1,10-phenanthroline (Phen) or 2,2'-bipyridyl (Bipy) and X=ClO4-, NO3- or Br- have been synthesized and characterized by the analytical and spectral methods, as well as magnetic and molar conductance measurements. The d-d absorption bands of Me4en-chelates as Nujol mulls or weak donor solvents solutions revealed square-planar, distorted octahedral and/or distorted trigonal bipyramid geometries for the perchlorate, nitrate and bromide chelates, respectively. However, an octahedral structure is identified for chelates in strong donor solvents. Perchlorate chelates show a remarkable color change from violet to green as the Lewis basicity of the donor solvent increases, whereas bromide chelates are mainly affected by the Lewis acidity of solvent. Specific and non-specific interactions of solvent molecules with the chelates were investigated on the basis of unified solvation model. Structural parameters of the free ligands and their Cu(II)-chelates have been calculated on the basis of semiempirical PM3 level and correlated with the experimental data. PMID:25589389

  18. Chelation as a weathering mechanism--I. Effect of complexing agents on the solubilization of iron from minerals and granodiorite

    Microsoft Academic Search

    E. B. Sohalscha; H. Appelt; A. Schatz

    1967-01-01

    This work is a continuation of previous studies on the role of chelation as a weathering mechanism. Salicylate and several naturally-occurring chelating agents, in the form of free acids or their alkali salts, extracted Fe from goethite, hematite, magnetite, epidote, augite, biotite and granodiorite. The removal of Fe from granodiorite by salicylate was demonstrable within a matter of minutes and

  19. Improvement of Oxidative and Metabolic Parameters by Cellfood Administration in Patients Affected by Neurodegenerative Diseases on Chelation Treatment

    PubMed Central

    Fulgenzi, Alessandro; Giuseppe, Rachele De; Bamonti, Fabrizia; Ferrero, Maria Elena

    2014-01-01

    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

  20. Total phenolic contents, chelating capacities, and radical-scavenging properties of black peppercorn, nutmeg, rosehip, cinnamon and oregano leaf

    Microsoft Academic Search

    Lan Su; Jun-Jie Yin; Denys Charles; Kequan Zhou; Jeffrey Moore

    2007-01-01

    Black peppercorn, nutmeg, rosehip, cinnamon and oregano leaf were extracted with 50% acetone and 80% methanol, and evaluated for their radical-scavenging activities against cation (ABTS+), DPPH, peroxyl (ORAC) and hydroxyl (HO) radicals. For each extract, total phenolic content (TPC) and chelating activity were also determined. The extracts of all botanical samples showed significant radical-scavenging capacities, TPC and chelating abilities. The

  1. Iron and iron chelating agents modulate Mycobacterium tuberculosis growth and monocyte-macrophage viability and effector functions

    Microsoft Academic Search

    Nicole Edmondson; Kathleen D. Eisenach; Liza Bornman

    2005-01-01

    Excess of iron promotes Mycobacterium tuberculosis infection, its replication and progression to clinical disease and death from tuberculosis. Chelation of iron may reduce M. tuberculosis replication, restore host defence mechanisms and it could constitute an application in the prevention and treatment strategies where both iron overload and tuberculosis are prevalent. We investigated the effect of iron and iron chelating agents,

  2. Antifungal Activities of Natural and Synthetic Iron Chelators Alone and in Combination with Azole and Polyene Antibiotics against Aspergillus fumigatus

    Microsoft Academic Search

    Kol A. Zarember; Anna R. Cruz; Chiung-Yu Huang; John I. Gallin

    2009-01-01

    Antifungal effects of iron chelators (lactoferrin, deferoxamine, deferiprone, and ciclopirox) were tested alone and in combination with antifungal drugs against Aspergillus fumigatus B5233 conidia. Lactoferrin, ciclopirox, and deferiprone inhibited whereas deferoxamine enhanced fungal growth. Antifungal synergy against conidia was observed for combinations of ketoconazole with ciclopirox or deferiprone, lactoferrin with amphotericin B, and fluconazole with deferiprone. Iron chelation alone or

  3. Affinity Partitioning of Metal Ions in Aqueous Polyethylene Glycol\\/Salt Two-Phase Systems with PEG-Modified Chelators

    Microsoft Academic Search

    P. A. Aguiñaga-DÍAz; R. Z. Guzman

    1996-01-01

    The systematic partitioning of metal ions in the presence of polyethylene glycol (PEG) chelate derivatives in PEG\\/salt two-phase systems is described. Results show that the partitioning is enhanced significantly, and this effect is apparently based on the characteristics of binding of the chelate and the nature of the metal ion in addition to the effect of the attached PEG molecule.

  4. Comparison of natural organic acids and synthetic chelates at enhancing phytoextraction of metals from a multi-metal contaminated soil

    Microsoft Academic Search

    Clístenes Williams A. do Nascimento; Dula Amarasiriwardena; Baoshan Xing

    2006-01-01

    Chemically assisted phytoremediation has been developing to induce accumulation of metals by high biomass plants. Synthetic chelates have shown high effectiveness to reach such a goal, but they pose serious drawbacks in field application due to the excessive amount of metals solubilized. We compared the performance of synthetic chelates with naturally occurring low molecular weight organic acids (LMWOA) in enhancing

  5. The Effect of N-Alkyl Modification on the Antimalarial Activity of 3-Hydroxypyridin-4One Oral Iron Chelators

    Microsoft Academic Search

    C. Hershko; E. N. Theanacho; D. T. Spira; H. H. Peter; P. Dobbin; R. C. Hider

    1991-01-01

    The antimalarial effect of iron chelators is attributed to their interaction with a labile iron pool within parasitised erythro- cytes, and it was postulated that increased affinity to iron as well as increased lipophilicity may improve antimalarial activity. In the present study we have examined the antima- larial effect of 3-hydroxypyridin-4-ones, a family of bidentate orally effective iron chelators whose

  6. Nanoparticle-chelator conjugates as inhibitors of amyloid-beta aggregation and neurotoxicity: a novel therapeutic approach for Alzheimer disease.

    PubMed

    Liu, Gang; Men, Ping; Kudo, Wataru; Perry, George; Smith, Mark A

    2009-05-22

    Oxidative stress and amyloid-beta are considered major etiological and pathological factors in the initiation and promotion of neurodegeneration in Alzheimer disease (AD). Insomuch as causes of such oxidative stress, transition metals, such as iron and copper, which are found in high concentrations in the brains of AD patients and accumulate specifically in the pathological lesions, are viewed as key contributors to the altered redox state. Likewise, the aggregation and toxicity of amyloid-beta is dependent upon transition metals. As such, chelating agents that selectively bind to and remove and/or "redox silence" transition metals have long been considered as attractive therapies for AD. However, the blood-brain barrier and neurotoxicity of many traditional metal chelators has limited their utility in AD or other neurodegenerative disorders. To circumvent this, we previously suggested that nanoparticles conjugated to iron chelators may have the potential to deliver chelators into the brain and overcome such issues as chelator bioavailability and toxic side-effects. In this study, we synthesized a prototype nanoparticle-chelator conjugate (Nano-N2PY) and demonstrated its ability to protect human cortical neurons from amyloid-beta-associated oxidative toxicity. Furthermore, Nano-N2PY nanoparticle-chelator conjugates effectively inhibited amyloid-beta aggregate formation. Overall, this study indicates that Nano-N2PY, or other nanoparticles conjugated to metal chelators, may provide a novel therapeutic strategy for AD and other neurodegenerative diseases associated with excess transition metals. PMID:19429118

  7. Chelating resins VII: studies on chelating resins of formaldehyde and furfuraldehyde-condensed phenolic Schiff base derived from 4,4?-diaminodiphenylsulphone and o-hydroxyacetophenone

    Microsoft Academic Search

    S Samal; N. K Mohapatra; S Acharya; R. K Dey

    1999-01-01

    The synthesis, characterization and capacity studies of two chelating resins having multiple functional groups capable of coordinating to several metal ions are reported. The resins were synthesized by condensing phenolic Schiff bases derived from 4,4?-diaminodiphenylsulphone and o-hydroxyacetophenone with formaldehyde\\/furfuraldehyde. The polymeric Schiff bases were found to form complexes readily with several transition metal ions. The resins were completely soluble in

  8. Long-term trial with the oral iron chelator 1,2-dimethyl-3-hydroxypyrid-4-one (L1). I. Iron chelation and metabolic studies.

    PubMed

    Kontoghiorghes, G J; Bartlett, A N; Hoffbrand, A V; Goddard, J G; Sheppard, L; Barr, J; Nortey, P

    1990-10-01

    A long-term clinical trial of 1-15 months has been carried out with the oral iron chelator 1,2-dimethyl-3-hydroxypyrid-4-one (L1) in 13 transfusion-dependent iron-loaded patients. Urinary iron excretion was greatest in patients with thalassaemia major and was related to the number of previous transfusions but not to the serum ferritin level. Substantial increases of urinary iron were observed in all the patients when the frequency of the daily dose was doubled and in response to 2 x 3 g L1 daily 11 of 12 patients tested excreted greater than 25 mg iron daily, the mean daily intake of iron from transfusion. Serum ferritin levels have fluctuated but overall have remained unchanged. Pharmacological studies in five patients have indicated rapid absorption probably from the stomach and variable plasma half life of 77 +/- 35 min (X +/- SD). Glucuronation was identified as a major route of L1 metabolism. Short-term intensive chelation studies using repeated administration of L1 resulted in further increases of urinary iron excretion by comparison to a single dose. In one case 325 mg of iron were excreted in the urine following the administration of 16 g (5 x 2 g + 2 x 3 g) within 24 h. Iron excretion studies were carried out in six transfusional iron-loaded patients who were maintained on a low iron diet before and during chelation. No significant increases of faecal iron excretion were observed with L1 using daily doses of up to 3 x 3 g and 4 x 2 g. The high level of compliance during treatment with L1 and the levels of urine iron excretion that can be achieved increase the prospects for oral chelation in transfusional iron-loaded patients. PMID:2094333

  9. Amine-Chelated Aryllithium ReagentssStructure and Dynamics Hans J. Reich,* Wayne S. Goldenberg, Birgir O2 . Gudmundsson, Aaron W. Sanders,

    E-print Network

    Reich, Hans J.

    ,5-dimethyltetrahydrofuran). The effect of cosolvents such as TMEDA, PMDTA, and HMPA has also been determined. All compounds are strongly chelated, and the chelation is not disrupted by these cosolvents. Reagents 1, 2, and 3 are dimeric

  10. Transfusional iron overload and chelation therapy with deferoxamine and deferiprone (L1).

    PubMed

    Kontoghiorghes, G J; Pattichi, K; Hadjigavriel, M; Kolnagou, A

    2000-12-01

    Iron is essential for all living organisms. Under normal conditions there is no regulatory and rapid iron excretion in humans and body iron levels are mainly regulated from the absorption of iron from the gut. Regular blood transfusions in thalassaemia and other chronic refractory anaemias can result in excessive iron deposition in tissues and organs. This excess iron is toxic, resulting in tissue and organ damage and unless it is removed it can be fatal to those chronically transfused. Iron removal in transfusional iron overload is achieved using chelation therapy with the chelating drugs deferoxamine (DF) and deferiprone (L1). Effective chelation therapy in chronically transfused patients can only be achieved if iron chelators can remove sufficient amounts of iron, equivalent to those accumulated in the body from transfusions, maintaining body iron load at a non-toxic level. In order to maintain a negative iron balance, both chelating drugs have to be administered almost daily and at high doses. This form of administration also requires that a chelator has low toxicity, good compliance and low cost. DF has been a life-saving drug for thousands of patients in the last 40 years. It is mostly administered by subcutaneous infusion (40-60 mg/kg, 8-12 h, 5 days per week), is effective in iron removal and has low toxicity. However, less than 10% of the patients requiring iron chelation therapy worldwide are able to receive DF because of its high cost, low compliance and in some cases toxicity. In the last 10 years we have witnessed the emergence of oral chelation therapy, which could potentially change the prognosis of all transfusional iron-loaded patients. The only clinically available oral iron chelator is L1, which has so far been taken by over 6000 patients worldwide, in some cases daily for over 10 years, with very promising results. L1 was able to bring patients to a negative iron balance at doses of 50-120 mg/kg/day. It increases urinary iron excretion, decreases serum ferritin levels and reduces liver iron in the majority of chronically transfused iron-loaded patients. Despite earlier concerns of possible increased risk of toxicity, all the toxic side effects of L1 are currently considered reversible, controllable and manageable. These include agranulocytosis (0.6%), musculoskeletal and joint pains (15%), gastrointestinal complaints (6%) and zinc deficiency (1%). The incidence of these toxic side effects could in general be reduced by using lower doses of L1 or combination therapy with DF. Combination therapy could also benefit patients experiencing toxicity with DF and those not responding to either chelator alone. The overall efficacy and toxicity of L1 is comparable to that of DF in both animals and humans. Despite the steady progress in iron chelation therapy with DF and L1, further investigations are required for optimising their use in patients by selecting improved dose protocols, by minimising their toxicity and by identifying new applications in other diseases of iron imbalance. PMID:11099897

  11. Temporal trends of anthropogenic SO2 emitted by non-ferrous metal smelters in Peru and Russia estimated from Satellite observations

    Microsoft Academic Search

    M. F. Khokhar; U. Platt; T. Wagner

    2008-01-01

    We report on satellite observations of atmospheric Sulfur Dioxide (SO2) emitted from metal smelting industries in Peru, South America and Siberia, Russia. Most of the non-ferrous metal ores are sulfidic and during the smelting process the sulfur is emitted as SO2. In addition to Norilsk, Russia, Peruvian copper smelters are among the most polluting point sources in the world. We

  12. 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

    Microsoft Academic Search

    T. A. Fowler; F. K. Crundwell

    1999-01-01

    This paper reports the results of leaching experiments conducted with and without Thiobacillus ferroxidans 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, which no sulfur

  13. TREATMENT OF A SATURATED ZONE HEXAVALENT CHROMIUM SOURCE AREA USING A FERROUS SULFATE/SODIUM DITHIONITE MIXTURE: A FIELD PILOT STUDY

    EPA Science Inventory

    A field pilot study was conducted to evaluate the performance of a combined ferrous sulfate/sodium dithionite solution for in situ treatment of a saturated zone hexavalent chromium source area at a former ferrochromium alloy production facility in Charleston, S.C. The saturate...

  14. Ironing iron out in Parkinson's disease and other neurodegenerative diseases with iron chelators: a lesson from 6-hydroxydopamine and iron chelators, desferal and VK-28.

    PubMed

    Youdim, Moussa B H; Stephenson, Galia; Ben Shachar, Dorit

    2004-03-01

    In Parkinson's disease (PD) and its neurotoxin-induced models, 6-hydroxydopamine (6-OHDA) and N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), significant accumulation of iron occurs in the substantia nigra pars compacta. The iron is thought to be in a labile pool, unbound to ferritin, and is thought to have a pivotal role to induce oxidative stress-dependent neurodegeneration of dopamine neurons via Fenton chemistry. The consequence of this is its interaction with H(2)O(2) to generate the most reactive radical oxygen species, the hydroxyl radical. This scenario is supported by studies in both human and neurotoxin-induced parkinsonism showing that disposition of H(2)O(2) is compromised via depletion of glutathione (GSH), the rate-limiting cofactor of glutathione peroxide, the major enzyme source to dispose H(2)O(2) as water in the brain. Further, radical scavengers have been shown to prevent the neurotoxic action of the above neurotoxins and depletion of GSH. However, our group was the first to demonstrate that the prototype iron chelator, desferal, is a potent neuroprotective agent in the 6-OHDA model. We have extended these studies and examined the neuroprotective effect of intracerebraventricular (ICV) pretreatment with the prototype iron chelator, desferal (1.3, 13, 134 mg), on ICV induced 6-OHDA (250 micro g) lesion of striatal dopamine neurons. Desferal alone at the doses studied did not affect striatal tyrosine hydroxylase (TH) activity or dopamine (DA) metabolism. All three pretreatment (30 min) doses of desferal prevented the fall in striatal and frontal cortex DA, dihydroxyphenylacetic acid, and homovalinic acid, as well as the left and right striatum TH activity and DA turnover resulting from 6-OHDA lesion of dopaminergic neurons. A concentration bell-shaped neuroprotective effect of desferal was observed in the striatum, with 13 micro g being the most effective. Neither desferal nor 6-OHDA affected striatal serotonin, 5-hydroxyindole acetic acid, or noradrenaline. Desferal also protected against 6-OHDA-induced deficit in locomotor activity, rearing, and exploratory behavior (sniffing) in a novel environment. Since the lowest neuroprotective dose (1.3 micro g) of desferal was 200 times less than 6-OHDA, its neuroprotective activity may not be attributed to interference with the neurotoxin activity, but rather iron chelation. These studies led us to develop novel brain-permeable iron chelators, the VK-28 series, with iron chelating and neuroprotective activity similar to desferal for ironing iron out from PD and other neurodegenerative diseases, such as Alzheimer's disease, Friedreich's ataxia, and Huntington's disease. PMID:15105275

  15. Evaluation of effects of Ma??urabhasma on structural and functional integrity of small intestine in comparison with ferrous sulfate using an experimental model of iron deficiency anemia

    PubMed Central

    Gawde, Suchita Rajanikant; Patel, Tejal C.; Rege, Nirmala N.; Gajbhiye, Snehalata; Uchil, Dinesh

    2015-01-01

    Background: The present study was planned to assess effects of Ma??urabhasma (MB) on structural and functional integrity of small intestine using an animal model of iron deficiency anemia (IDA) in rat. Methods: IDA was induced by giving iron deficient diet and retro-orbital bloodletting for 21 days in Wistar female rats. Rats (n = 72) were divided into six groups: (i) Control group, (ii) IDA rats, (iii) IDA rats receiving vehicle, (iv) rats receiving ferrous sulfate (40 mg/kg), (vi) rats receiving a low dose (22.5 mg/kg) of MB, (vi) rats receiving a high dose (45 mg/kg) of MB. Treatment was conducted for a period of 21 days followed by an assessment of change in hemoglobin (Hb) levels, lactase levels, lipid peroxidation activity by measuring malondialdehyde (MDA) levels and jejunal morphometry. Results: In the present study, the lactase activity was markedly reduced in iron-deficient rats. Our study has demonstrated that intestinal morphology and MDA levels were not altered in the animals with IDA as compared to normal animals. In phase II, improvement in Hb response to ferrous sulfate was accompanied by an improvement in lactase activity. However, it significantly increased MDA levels with derangement of the normal villous structure. Rats receiving a low dose of MB did not have increased MDA levels. It did not alter the jejunal villous structure and improved lactase activity, but hematinic activity was found to be less than that of ferrous sulfate. Rats receiving a high dose of MB showed significantly improved Hb as well as lactase levels. They exhibited damage to the villous structure and increased MDA levels, but the effects were significantly less as compared to ferrous sulfate group. Conclusion: Rats receiving a high dose of MB have shown improvement in hematinic and lactase levels comparable to those receiving ferrous sulfate. However, it causes lesser oxidative damage as compared to ferrous sulfate. This is an encouraging finding because it indicates the potential of MB to cause lesser gastrointestinal side effects compared to ferrous sulfate. PMID:26120227

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

    PubMed

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

    2012-01-01

    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

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

    NASA Technical Reports Server (NTRS)

    Miyoshi, K.; Buckley, D. H.

    1982-01-01

    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.

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

    PubMed

    Nezamzadeh-Ejhieh, Alireza; Shirzadi, Arezoo

    2014-07-01

    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

  19. Flavonoids function as antioxidants: By scavenging reactive oxygen species or by chelating iron?

    NASA Astrophysics Data System (ADS)

    Wuguo, Deng; Xingwang, Fang; Jilan, Wu

    1997-09-01

    Flavonoids have been reported to exhibit strong antioxidative activity. In the present work, a systematic mechanistic study has been performed on five flavonoids (baicalin, hesperidin, naringin, quercetin and rutin) selected according to their structural characteristics. The experimental results reveal that flavonoids function as antioxidant mainly by chelating iron ions and by scavenging peroxyl radicals whereas their OH radical scavenging effect is much less important.

  20. In vitro screening of Fe2+-chelating effect by a Fenton's reaction-luminol chemiluminescence system.

    PubMed

    Wada, Mitsuhiro; Komatsu, Hiroaki; Ikeda, Rie; Aburjai, Talal A; Alkhalil, Suleiman M; Kuroda, Naotaka; Nakashima, Kenichiro

    2014-11-01

    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. PMID:24403191

  1. Iron Chelators in Photodynamic Therapy Revisited: Synergistic Effect by Novel Highly Active Thiosemicarbazones

    PubMed Central

    2014-01-01

    In photodynamic therapy (PDT), a noninvasive anticancer treatment, visible light, is used as a magic bullet selectively destroying cancer cells by a photosensitizer that is nontoxic in the dark. Protoporphyrin IX (PpIX) is a natural photosensitizer synthesized in the cell, which is also a chelating agent that if bonded to Fe2+ forms heme, a central component of hemoglobin. Therefore, xenobiotic iron chelators can disturb iron homeostasis, increasing the accumulation of PpIX, obstructing the last step of heme biosynthesis, and enhancing PDT efficiency. However, the attempts to use this promising idea have not proved to be hugely successful. Herein, we revisited this issue by analyzing the application of iron chelators highly toxic in the dark, which should have higher Fe2+ affinity than the nontoxic chelators used so far. We have designed and prepared thiosemicarbazones (TSC) with the highest dark cellular cytotoxicity among TSCs ever reported. We demonstrate that compound 2 exerts powerful PDT enhancement when used in combination with 5-aminolevulinic acid (ALA), a precursor of PpIX. PMID:24900837

  2. Surface immobilizable chelator for label-free electrical detection of pyrophosphate.

    PubMed

    Liu, David J; Credo, Grace M; Su, Xing; Wu, Kai; Lim, Hsiao C; Elibol, Oguz H; Bashir, Rashid; Varma, Madoo

    2011-08-01

    A new pyrophosphate (PPi) chelator was designed for surface-sensitive electrical detection of biomolecular reactions. This article describes the synthesis of the PPi-selective receptor, its surface immobilization and application to label-free electrical detection on a silicon-based field-effect transistor (FET) sensor. PMID:21687892

  3. Metal chelate catalysts for fuel cells. Final report June 1979 - October 1982

    Microsoft Academic Search

    R. Darby; M. Yamana; H. Dhar; R. White

    1982-01-01

    Various modified forms of several organometallic chelate compounds were synthesized and tested for their activity and stability as oxygen reduction electrocatalysts in sulfuric acid electrolyte. The most active catalysts found were cobalt tetraazaannulene (CoTAA), iron phthalocyanine (FePc) and cobalt tetraphenylporphyrin (CoTPP). However, these catalysts have limited stability in strong acids.

  4. Metal chelate catalysts for fuel cells. Final report June 1979 - October 1982

    SciTech Connect

    Darby, R.; Yamana, M.; Dhar, H.; White, R.

    1982-10-01

    Various modified forms of several organometallic chelate compounds were synthesized and tested for their activity and stability as oxygen reduction electrocatalysts in sulfuric acid electrolyte. The most active catalysts found were cobalt tetraazaannulene (CoTAA), iron phthalocyanine (FePc) and cobalt tetraphenylporphyrin (CoTPP). However, these catalysts have limited stability in strong acids.

  5. Iron-chelation properties of phenolic acids bearing catechol and galloyl groups

    Microsoft Academic Search

    Mirjana Andjelkovi?; John Van Camp; Bruno De Meulenaer; Griet Depaemelaere; Carmen Socaciu; Marc Verloo; Roland Verhe

    2006-01-01

    In this study, the capacity of seven phenolic acids and hydroxytyrosol for complex formation with iron was quantified. A metal-chelation mechanism was described by means of spectrophotometry and calculating the binding constants of the complexes. The influence of phosphate buffer, Hepes buffer, Tris buffer and water on this mechanism was investigated. UV–Vis absorption spectroscopy showed that the absorption of phenolic

  6. [Effect of a copper-chelating peptide on the anticancer activity of anthraquinones].

    PubMed

    Morier-Teissier, E

    1990-01-01

    Pseudopeptides incorporating a polyhydroxyanthraquinone ring related to the nuclei of the antitumor drug Mitoxantrone and a peptidic metal-chelating moiety Gly-His-Lys (GHK), have been synthesized. The goal was to conjugate the redox effects of a quinone ring with the iron chelating properties of the peptide in order to generate free radical species capable of damaging DNA. DHQ-GHK has a moderate affinity for DNA but causes precipitation of filaments. Electron microscopy shows a loop-making organization, DNA molecules having a lengthening superior to 50% as compared to control supercoiled DNA, the inside of these loops looks free of granular deposit. The peptidic moiety forms a complex with copper when the ratio Cu/P is lower than 0.2. This cupric complex catalyses the formation of free radicals and the cleavage of the DNA double strand. A new synthesis is described involving the addition of a space arm between the anthraquinonic nucleus and copper chelating compounds to obtain derivates disubstituted by different chelators. PMID:2086758

  7. Luminescent solutions and films of new europium complexes with chelating ligands

    NASA Astrophysics Data System (ADS)

    Kharcheva, Anastasia V.; Ivanov, Alexey V.; Borisova, Nataliya E.; Kaminskaya, Tatiana P.; Patsaeva, Svetlana V.; Popov, Vladimir V.; Yuzhakov, Viktor I.

    2015-03-01

    The development of new complexes of rare earth elements (REE) with chelating organic ligands opens up the possibility of purposeful alteration in the composition and structure of the complexes, and therefore tuning their optical properties. New ligands possessing two pyridine rings in their structure were synthesized to improve coordination properties and photophysical characteristics of REE compounds. Complexes of trivalent europium with novel chelating ligands were investigated using luminescence and absorption spectroscopy, as well as atomic force microscopy. Luminescence properties of new compounds were studied both for solutions and films deposited on the solid support. All complexes exhibit the characteristic red luminescence of Eu (III) ion with the absolute lumenescence quantum yield in polar acetonitrile solution varying from 0.21 to 1.45 % and emission lifetime ranged from 0.1 to 1 ms. Excitation spectra of Eu coordination complexes correspond with absorption bands of chelating ligand. The energy levels of the triplet state of the new ligands were determined from the phosphorescence at 77 K of the corresponding Gd (III) complexes. The morphology of films of europium complexes with different substituents in the organic ligands was investigated by atomic force microscopy (AFM). It strongly depends both on the type of substituent in the organic ligand, and the rotation speed of the spin-coater. New europium complexes with chelating ligands containing additional pyridine fragments represent outstanding candidates for phosphors with improved luminescence properties.

  8. Regulation of glucose transport and GLUT-1 expression by iron chelators in muscle cells in culture.

    PubMed

    Potashnik, R; Kozlovsky, N; Ben-Ezra, S; Rudich, A; Bashan, N

    1995-12-01

    Possible association between the degree of iron load and glucose metabolism has been postulated by both in vivo and in vitro studies. Because skeletal muscle plays a major role in whole body glucose utilization, we evaluated the effect of iron chelators deferoxamine (DFO) and bipyridyl (Bip) on glucose metabolism and transport in cultured L6 muscle cells. Bip (0.1 mM) or DFO (0.5 mM) added for 24 h to the culture medium increased glucose consumption, lactate production, and [14C]glucose incorporation into glycogen by approximately twofold. 2-Deoxy-glucose uptake by L6 myotubes increased time dependently, reaching a 5-fold and 2.5-fold increase after 12 h for Bip and DFO, respectively. Insulin induced a 2.5-fold increase in glucose uptake in untreated cells, which was additive to the chelator's effect. Iron chelator-induced glucose transport stimulation was inhibited by cycloheximide (2.5 micrograms/ml), indicating dependence on de novo protein synthesis. Increases in GLUT-1 protein and mRNA concentration, without changes in GLUT-4, were found to be responsible for iron chelator effects. We conclude that L6 cells adapt to reduction in iron availability by increasing glucose utilization through an enhanced expression of GLUT-1, without losing their physiological response to insulin. PMID:8572196

  9. Chemical characterization and reactivity of iron chelator-treated amphibole asbestos.

    PubMed Central

    Gold, J; Amandusson, H; Krozer, A; Kasemo, B; Ericsson, T; Zanetti, G; Fubini, B

    1997-01-01

    Iron in amphibole asbestos is implicated in the pathogenicity of inhaled fibers. Evidence includes the observation that iron chelators can suppress fiber-induced tissue damage. This is believed to occur via the diminished production of fiber-associated reactive oxygen species. The purpose of this study was to explore possible mechanisms for the reduction of fiber toxicity by iron chelator treatments. We studied changes in the amount and the oxidation states of bulk and surface iron in crocidolite and amosite asbestos that were treated with iron-chelating desferrioxamine, ferrozine, sodium ascorbate, and phosphate buffer solutions. The results have been compared with the ability of the fibers to produce free radicals and decompose hydrogen peroxide in a cell-free system in vitro. We found that chelators can affect the amount of iron at the surface of the asbestos fibers and its valence, and that they can modify the chemical reactivity of these surfaces. However, we found no obvious or direct correlations between fiber reactivity and the amount of iron removed, the amount of iron at the fiber surface, or the oxidation state of surface iron. Our results suggest that surface Fe3+ ions may play a role in fiber-related carboxylate radical formation, and that desferrioxamine and phosphate groups detected at treated fiber surfaces may play a role in diminishing and enhancing, respectively, fiber redox activity. It is proposed that iron mobility in the silicate structure may play a larger role in the chemical reactivity of asbestos than previously assumed. PMID:9400694

  10. Iron chelation with deferasirox in a patient with de-novo ferroportin mutation.

    PubMed

    Unal, Sule; Piperno, Alberto; Gumruk, Fatma

    2015-04-01

    Ferroportin disease is a rare type of autosomal dominantly inherited hemochromatosis caused with mutations in the ferroportin gene (SLC40A1). The patients characteristically have hyperferritinemia but normal transferin saturations. Herein, we present a 15-year-old female whose chief complaint was persistent nausea for the last one year. Extensive work-up including brain imaging revealed nothing to explain the etiology of nausea. The serum ferritin level of 1474ng/mL was suggestive for hemochromatosis syndromes and the molecular testing revealed de-novo c.485_487delTTG (P.Val162del) ferroportin gene mutation. Mild hepatic iron loading, in addition to the cumbersome nausea were accepted as indications for chelation treatment in this particular patient and deferasirox was initiated (10mg/kg/day) since family did not consent for phlebotomy. Deferasirox was stopped by the 9th month of initiation, since nausea subsided and hepatic iron content was normalized, in order to prevent over chelation. There are no well-established guidelines for the chelation of patients with hereditary hemochromatosis syndromes. However, lifelong monitorization for iron loading and re-initiation of chelation when necessary was planned in our patient. PMID:25744502

  11. Interaction forces between metal-chelating lipid monolayers measured by colloidal probe atomic force microscopy

    Microsoft Academic Search

    Ryo Ishiguro; Darryl Y Sasaki; Charles Pacheco; Kazue Kurihara

    1999-01-01

    Surface forces between LB films of metal-chelating lipids in water have been studied using colloidal probe atomic force microscopy. The LB films of an amphiphile functionalized by the iminodiacetic acid group were prepared on hydrophobic glass substrates. The electric double layer repulsion operated between these LB film surfaces changed depending on pH reflecting the different protonation states of the iminodiacetic

  12. [Enhanced phytoextraction of heavy metal contaminated soil by chelating agents and auxin indole-3-acetic acid].

    PubMed

    Zhou, Jian-min; Dang, Zhi; Chen, Neng-chang; Xu, Sheng-guang; Xie, Zhi-yi

    2007-09-01

    The environmental risk of chelating agents such as EDTA application to the heavy metals polluted soils and the stress on plant roots due to the abrupt increase metals concentration limit the wide commercial use of chelate-induced phytoextraction. Chelating agent ethylenediaminetetraacetic acid (EDTA) and nitrilotriacetic acid (NTA) and auxin indole-3-acetic acid (IAA) were used for enhancing heavy metals uptake from soils by Zea mays L. (corn) in pot experiments. The metals content in plant tissues was quantified using an inductively coupled plasma mass spectrometer (ICP-MS). The results showed that the combination of IAA and EDTA increased the biomass by about 40.0% and the contents of Cu, Zn, Cd and Pb in corn shoots by 27.0%, 26.8%, 27.5% and 32.8% respectively, as compared to those in EDTA treatment. While NTA&IAA treatment increased the biomass by about 29.9% and the contents of Cu, Zn, Cd and Pb in corn shoots by 31.8%, 27.6%, 17.0% and 26.9% respectively, as compared to those in NTA treatment. These results indicated that corn growth was promoted, and the biomass and the accumulation of heavy metals in plant shoots were increased significantly with the addition of IAA, which probably helps to change the cell membrane properties and the biomass distribution, resulting in the alleviation of the phytotoxicity of metals and the chelating agents. PMID:17990562

  13. Growth and Decay: An Experiment Demonstrating Radioactivity Relationships and Chelate Solvent Extraction Separations.

    ERIC Educational Resources Information Center

    Downey, D. M.; And Others

    1984-01-01

    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)

  14. Modern Chemistry Techniques Applied to Metal Behavior and Chelation in Medical and Environmental Systems ? Final Report

    SciTech Connect

    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

    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.

  15. Resolution of Optical Isomers as the Mixed Chelate Copper(III) Complexes by Reversed Phase Chromatography

    Microsoft Academic Search

    Stanley Lam; Arthur Karmen

    1986-01-01

    Highly selective separation of D and L amino acids can be effected by reversed phase chromatography of mixed chelate complexes of the analyte acids with equimolar concentrations of Cu(II) and an optically active second amino acid in the mobile phase. The stabilities of the formed diastereomeric ternary complexes will determine the resolution of enantiomers. By this approach, amino acids were

  16. Oral chelators deferasirox and deferiprone for transfusional iron overload in thalassemia major: new data, new questions

    Microsoft Academic Search

    Ellis J. Neufeld

    For nearly 30 years, patients with transfu- sional iron overload have depended on nightly deferoxamine infusions for iron chelation. Despite dramatic gains in life expectancy in the deferoxamine era for patients with transfusion-dependent ane- mias, the leading cause of death for young adults with thalassemia major and related disorders has been cardiac disease from myocardial iron deposition. Strategies to reduce

  17. The preparation and characterization of novel human-like collagen metal chelates.

    PubMed

    Zhu, Chenhui; Sun, Yan; Wang, Yaoyu; Luo, Yane; Fan, Daidi

    2013-07-01

    In order to develop the nutritional trace elements which could be absorbed and utilized effectively, protein chelates were adopted. Calcium, copper and manganese were considered based on their physiological functions, and the new chelates of HLC-Ca, HLC-Cu and HLC-Mn were formed in MOPS or MES buffer and purified by gel chromatography, and then freeze-dried. And they were detected and analyzed by atomic absorption spectrophotometry, ultraviolet-visible absorption (UV-vis) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, fluorescence quenching method, circular dichroism (CD) and differential scanning calorimetry (DSC). The results showed that some chemical reactions happened between HLC and the three metal ions to form new chemical compounds. The thermodynamic parameters, ?H, ?G and ?S, showed that the chelation process between HLC and metal ions was performed spontaneously. Fluorescence quenching spectra of HLC indicated that the quenching mechanism was static in nature. According to the data of DSC, the new chelates were more stable than the free HLC. And HLC-metal complex was non-toxic to the BHK21 cell through MTT assay. PMID:23623075

  18. Polymeric precursor derived nanocrystalline ZnO thin films using EDTA as chelating agent

    E-print Network

    Mohanty, Saraju P.

    ], molecular beam epitaxy [11, 12], chemical vapor deposition [13], and sol­gel process [14-16]. However, thin, such as citric acid, is generally employed as the chelating agent. However, it has been proven that ethylene-depth. Citric acid in Pechini process has been replaced with EDTA as the complexing a

  19. Physicochemical characterization of the microbial Fe2+ chelator proferrorosamine from Pseudomonas roseus fluorescens.

    PubMed

    Vande Woestyne, M; Bruyneel, B; Verstraete, W

    1992-01-01

    The microbial chelating compound proferrorosamine A, produced by Pseudomonas roseus fluorescens, formed a complex with Fe2+ of which the apparent stability constant was found to be 10(23). The following order of increasing stability constants of metal complexes with proferrorosamine was established as: Ba2+, Ca2+, Mg2+, Mn2+ less than Hg2+ less than Zn2+ less than Pb2+ less than Co2+ less than Cu2+ congruent to Fe2+ less than Ni2+. Only Ni(2+)-proferrorosamine had a stability constant which was established as: Ba2+, Ca2+, Mg2+, Mn2+ less than Hg2+ less than Zn2+ less than Pb2+ less than Co2+ less than Cu2+ congruent to Fe2+ less than Ni2+. Only Ni(2+)-proferrorosamine had a stability constant which was ca 32 times higher than Fe(2+)-proferrorosamine. Because of the production of proferrorosamine the growth of Ps. roseus fluorescens was not inhibited in iron limiting media by the addition of 0.15 mmol/l of the weaker chemical Fe2+ chelator 2,2'-dipyridyl. This contrasted with the proferrorosamine-negative mutant K2 and Ps. stutzeri, which only produces Fe(3+)-chelating siderophores. Furthermore, it was found that proferrorosamine was able to dissolve Fe2+ from stainless steel. These results show that proferrorosamine is a strong and selective Fe2+ chelator which could be used as an alternative for the toxic 2,2'-dipyridyl to control lactic acid fermentations. PMID:1541599

  20. Biodegradable chelating agents for industrial, domestic, and agricultural applications--a review.

    PubMed

    Pinto, Isabel S S; Neto, Isabel F F; Soares, Helena M V M

    2014-10-01

    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

  1. Rates and mechanisms of reaction of hydrogen sulfide with iron chelates. Topical report, April 1993

    Microsoft Academic Search

    DeBerry

    1993-01-01

    Chelated iron liquid redox sulfur recovery processes hold promise for providing economical removal of hydrogen sulfide from natural gas with conversion to solid sulfur. They are complex chemical systems. An objective of this project is to identify and characterize the chemical interactions occurring in these liquid redox systems and determine which process parameters impact performance. This report presents the results

  2. Rates and mechanisms of reaction of hydrogen sulfide with iron chelates. Topical report, April 1993

    SciTech Connect

    DeBerry, D.W.

    1993-04-01

    Chelated iron liquid redox sulfur recovery processes hold promise for providing economical removal of hydrogen sulfide from natural gas with conversion to solid sulfur. They are complex chemical systems. An objective of this project is to identify and characterize the chemical interactions occurring in these liquid redox systems and determine which process parameters impact performance. This report presents the results of this project concerning the mechanism of oxidation of hydrogen sulfide by iron-based compounds in the liquid phase. The rates of reactions of chelated iron sorbing reagents with reduced sulfur species were measured over a wide range of conditions. The effects of relative reactant concentrations, pH, and ionic strength on these rates have been determined using a number of different methods. Effects of temperature and chelate type on the reaction of chelate iron with sulfide are also presented here. A kinetic model was developed to interpret these results and provide an overall framework for the reaction mechanism. This model has proven to be useful for integrating and explaining the results of the kinetics measurements. In addition, the model may become a useful tool for optimizing process chemistry and a key component of a general chemical process model. Details of the model and verification runs are given in this report.

  3. Iron chelating activity, phenol and flavonoid content of some medicinal plants from Iran

    Microsoft Academic Search

    Mohammad Ali Ebrahimzadeh; Fereshteh Pourmorad; Ahmad Reza Bekhradnia

    Thalassemia major is characterized by anemia, iron overload, further potentiation of reactive oxygen species (ROS) and damage to major organs, especially the cardiovascular system. Antioxidant and other supportive therapies protect red blood cells (RBC) against antioxidant damage. Chelation therapy reduces iron-related complications and thereby improves quality of life and overall survival. The poor oral bioavailability, short plasma half-life and severe

  4. Differential in vitro and cellular effects of iron chelators for hypoxia inducible factor hydroxylases.

    PubMed

    Cho, Eun A; Song, Hyun Kyung; Lee, Sang-Hyeup; Chung, Bong Hyun; Lim, Heon Man; Lee, Myung Kyu

    2013-04-01

    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

  5. 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...

  6. Investigating the Use of Chelating Agents for Clay Dissolution and Sandstone Acidizing Purposes 

    E-print Network

    Andotra, Gautam

    2014-08-06

    concentrations of citric acid (1 wt%, 3 wt%, and 5 wt%) added to regular 9:1 mud acid. This was done to study and analyze its clay dissolution properties, as well as its chelation abilities to reduce precipitation. For comparison purposes, experiments were also...

  7. Induced phytoextraction/soil washing of lead using biodegradable chelate and permeable barriers.

    PubMed

    Kos, Bostjan; Lestan, Domen

    2003-02-01

    Chelate-induced remediation has been proposed as an effective tool for the extraction of lead (Pb) from contaminated soils by plants. However, side-effects, mainly mobilization and leaching of Pb, raise environmental concerns. Biodegradable, synthetic organic chelate ethylenediaminedisuccinic acid (EDDS), and commonly used ethylenedimanetetraacetic acid (EDTA) were used for induced phytoextraction with a test plant Brassica rapa and in situ washing of soil contaminated with 1350 mg/kg of Pb. Horizontal permeable barriers were placed 20 cm deep in soil columns and tested for their ability to prevent leaching of Pb. The reactive materials in the barriers were nutrient enriched vermiculite, peat or agricultural hydrogel, and apatite. EDTA and EDDS addition increased Pb concentrations in the test plant by 158 and 89 times compared to the control, to 817 and 464 mg/kg, respectively. In EDTA treatments, approximately 25% or more of total initial soil Pb was leached in single cycle of chelate addition. In EDDS treatments, 20% of the initial Pb was leached from columns with no barrier, while barriers with vermiculite or hydrogel and apatite decreased leaching by more than 60 times, to 0.35%. 11.6% of total initial Pb was washed from the soil above the barrier with vermiculite and apatite, where almost all leached Pb was accumulated. Results indicate that use of biodegradable chelate EDDS and permeable barriers may lead to environmentally safe induced Pb phytoextraction and in situ washing of Pb. PMID:12630481

  8. Prevention of postischaemic lipid peroxidation and liver cell injury by iron chelation

    Microsoft Academic Search

    R Omar; I Nomikos; G Piccorelli; J Savino; N Agarwal

    1989-01-01

    Liver ischaemia was induced by cross clamping the hilar pedicle for 30 minutes in groups of rats with or without treatment with the iron chelating agent desferrioxamine (deferoxamine, DFR). The groups included eight animals each and were divided into the following treatment categories: control; ischaemia alone; ischaemia with subsequent reperfusion; ischaemia preceded by DFR, 60 mg\\/kg body weight; and reperfusion

  9. Neuroprotection by a novel brain permeable iron chelator, VK-28, against 6-hydroxydopamine lession in rats

    Microsoft Academic Search

    Dorit Ben Shachar; Nava Kahana; Vladimir Kampel; Abraham Warshawsky; Moussa B. H Youdim

    2004-01-01

    Significant increase in iron occurs in the substantia nigra pars compacta of Parkinsonian subjects, and in 6-hydroxydopamine (6-OHDA) treated rats and monkeys. This increase in iron has been attributed to its release from ferritin and is associated with the generation of reactive oxygen species and the onset of oxidative stress-induced neurodegeneration. Several iron chelators with hydroxyquinoline backbone were synthesized and

  10. Prevention of doxorubicin-induced myocardial and haematological toxicities in rats by the iron chelator desferrioxamine

    Microsoft Academic Search

    M. M. AI-Harbil; Naji M. Al-Gharably; Othman A. AI-Shabanahl; Abdullah M. Al-Bekairi; Abdel Moneim M. Osman; Hassan N. Tawfik

    1992-01-01

    Biochemical and histopathological evaluations of the protective effects of the iron-chelator desferrioxamine against the cardiac and haematological toxicities of doxorubicin in normal rats were carried out. A single dose of doxorubicin (15 mg\\/kg, i. v.) caused myocardial damage that manifested biochemically as an elevation of serum cardiac enzyme [glutamic oxaloacetic transaminase (GOT), lactic dehydrogenase (LDH) and creatine phosphokinase (CPK)] and

  11. Effect of a specific iron chelating agent on animal models of inflammation

    Microsoft Academic Search

    D R Blake; N D Hall; P A Bacon; P A Dieppe; B Halliwell; J M Gutteridge

    1983-01-01

    Iron is an important catalyst of oxidative radical reactions and promotes the formation of the hydroxyl radical from the superoxide anion radical and hydrogen peroxide. The stimulatory effect of the hydroxyl radical on lipid peroxidation prompted the speculation that free iron may directly promote inflammation and that iron chelating agents may have useful anti-inflammatory properties. This hypothesis is tested in

  12. 3Hydroxy(4 H)-benzopyran-4-ones as potential iron chelating agents in vivo

    Microsoft Academic Search

    Marco Ferrali; Donato Donati; Sabrina Bambagioni; Marco Fontani; Gianluca Giorgi; Antonello Pietrangelo

    2001-01-01

    Increasing evidence suggests that iron plays an important role in tissue damage both during chronic iron overload diseases (i.e., hemochromatosis) and when, in the absence of actual tissue iron overload, iron is delocalised from specific carriers or intracellular sites (inflammation, neurodegenerative diseases, post-ischaemic reperfusion, etc.). In order to be used for therapeutical purposes in vivo, a reliable iron chelator should

  13. Iron chelation-afforded cardioprotection against chronic anthracycline cardiotoxicity: A study of salicylaldehyde isonicotinoyl hydrazone (SIH)

    Microsoft Academic Search

    Martin Št?rba; Olga Popelová; TomᚠŠim?nek; Yvona Mazurová; Anna Potá?ová; Michaela Adamcová; Ivana Gun?ová; Helena Kaiserová; Vladimír Pali?ka; P?emysl Po?ka; Vladimír Geršl

    2007-01-01

    Pyridoxal-derived aroylhydrazone iron chelators have been previously shown as effective cardioprotectants against chronic anthracycline cardiotoxicity. In this study we focused on a novel salicylaldehyde analogue (salicylaldehyde isonicotinoyl hydrazone, SIH), which has been recently demonstrated to possess marked and dose-dependent protective effects against oxidative injury of cardiomyocytes. Therefore, in the present study the cardioprotective potential of SIH against daunorubicin (DAU) cardiotoxicity

  14. Reactivity of Deoxy- and Oxyferrous Dehaloperoxidase B from Amphitrite ornata: Identification of Compound II and its Ferrous-Hydroperoxide Precursor†

    PubMed Central

    D’Antonio, Jennifer; Ghiladi, Reza A.

    2011-01-01

    Dehaloperoxidase (DHP) from the terebellid polychaete Amphitrite ornata is a bifunctional enzyme that possesses both hemoglobin and peroxidase activities. The bifunctional nature of DHP as a globin-peroxidase appears to be at odds with the traditional starting oxidation state for each individual activity. Namely, reversible oxygen-binding is only mediated via a ferrous heme in globins, and peroxidase activity is initiated from ferric centers and to the exclusion of the oxyferrous oxidation state from the peroxidase cycle. Thus, to address what appears to be a paradox, herein we report the details of our investigations into the DHP catalytic cycle when initiated from the deoxy- and oxyferrous states using biochemical assays, stopped-flow UV-visible and rapid-freeze-quench electron paramagnetic resonance spectroscopies, and anaerobic methods. We demonstrate the formation of Compound II directly from deoxyferrous DHP B upon its reaction with hydrogen peroxide, and show that this occurs both in the presence and absence of trihalophenol. Prior to Compound II formation, we have identified a new species which we have preliminarily attributed to a ferrous-hydroperoxide precursor that undergoes heterolysis to generate the aforementioned ferryl intermediate. Taken together, the results demonstrate that the oxyferrous state in DHP is a peroxidase competent starting species, and an updated catalytic cycle for DHP is proposed in which the ferric oxidation state is not an obligatory starting point for the peroxidase catalytic cycle of dehaloperoxidase. The data presented herein provide a link between the peroxidase and oxygen transport activities which furthers our understanding of how this bifunctional enzyme is able to unite its two inherent functions in one system. PMID:21619067

  15. Carotenoids, but not vitamin A, improve iron uptake and ferritin synthesis by Caco-2 cells from ferrous fumarate and NaFe-EDTA.

    PubMed

    García-Casal, María N; Leets, Irene

    2014-04-01

    Due to the high prevalence of iron and vitamin A deficiencies and to the controversy about the role of vitamin A and carotenoids in iron absorption, the objectives of this study were to evaluate the following: (1) the effect of a molar excess of vitamin A as well as the role of tannic acid on iron uptake by Caco-2 cells; (2) iron uptake and ferritin synthesis in presence of carotenoids without pro-vitamin A activity: lycopene, lutein, and zeaxantin; and (3) iron uptake and ferritin synthesis from ferrous fumarate and NaFe-EDTA. Cells were incubated 1 h at 37 °C in PBS pH 5.5, containing (59) Fe and different iron compounds. Vitamin A, ferrous fumarate, ?-carotene, lycopene, lutein, zeaxantin, and tannic acid were added to evaluate uptake. Ferritin synthesis was measured 24 h after uptake experiments. Vitamin A had no effect on iron uptake by Caco-2 cells, and was significantly lower from NaFe-EDTA than from ferrous fumarate (15.2 ± 2.5 compared with 52.5 ± 8.3 pmol Fe/mg cell protein, respectively). Carotenoids increase uptake up to 50% from fumarate and up to 300% from NaFe-EDTA, since absorption from this compound is low when administered alone. We conclude the following: (1) There was no effect of vitamin A on iron uptake and ferritin synthesis by Caco-2cells. (2) Carotenoids significantly increased iron uptake from ferrous fumarate and NaFe-EDTA, and were capable of partially overcoming the inhibition produced by tannic acid. (3) Iron uptake by Caco-2 cell from NaFe-EDTA was significantly lower compared to other iron compounds, although carotenoids increased and tannic acid inhibited iron uptake comparably to ferrous fumarate. PMID:24665932

  16. Lead toxicosis of captive vultures: case description and responses to chelation therapy

    PubMed Central

    2013-01-01

    Background Lead, a serious threat for raptors, can hamper the success of their conservation. This study reports on experience with accidental lead intoxication and responses to chelation therapy in captive Cinereous (Aegypius monachus) and Egyptian (Neophron percnopterus) Vultures. Results Soil contamination by lead-based paint sanded off the steel aviary resulted in poisoning of eight Cinereous and two Egyptian Vultures. A male Egyptian Vulture developed signs of apathy, polydipsia, polyuria, regurgitation, and stupor, and died on the next day. Liver, kidney and blood lead concentrations were 12.2, 8.16 and 2.66 ?g/g, respectively. Laboratory analyses confirmed severe liver and kidney damage and anaemia. Blood Pb levels of Pb-exposed Cinereous Vultures were 1.571?±?0.510 ?g/g shortly after intoxication, decreased to 0.530?±?0.165 ?g/g without any therapy in a month and to 0.254?±?0.097 ?g/g one month after CaNa2EDTA administration. Eight months later, blood lead levels decreased to close to the background of the control group. Blood parameters of healthy Pb-non-exposed Cinereous Vultures were compared with those of the exposed group prior to and after chelation therapy. Iron levels in the lead-exposed pre-treatment birds significantly decreased after chelation. Haematocrit levels in Pb-exposed birds were significantly lower than those of the controls and improved one month after chelation. Creatine kinase was higher in pre-treatment birds than in the controls but normalised after therapy. Alkaline phosphatase increased after chelation. A marked increase in the level of lipid peroxidation measured as thiobarbituric acid reactive species was demonstrated in birds both prior to and after chelation. The ferric reducing antioxidant power was significantly lower in pre-treatment vultures and returned to normal following chelation therapy. Blood metallothionein levels in lead-exposed birds were higher than in controls. Reduced glutathione dropped after CaNa2EDTA therapy, while oxidised glutathione was significantly lower in both pre- and post-treatment birds. A chick in an egg produced by a Cinereous Vulture female two months after lead toxicosis died on day 40 of artificial incubation. Lead concentrations in foetal tissues were consistent with levels causing avian mortality. Conclusions The reported blood parameters and reproduction impairment in captive birds may have implications for professionals dealing with lead exposure in wild birds. PMID:23324224

  17. Uranyl complexes with diamide ligands: a quantum mechanics study of chelating properties in the gas phase.

    PubMed

    Coupez, Bernard; Wipff, Georges

    2003-06-01

    We report a quantum mechanical study on the complexes of UO(2)(2+) with diamide ligands L of malonamide and succinamide type, respectively, forming 6- and 7-chelate rings in their bidentate coordination to uranium. The main aims are to (i) assess how strong the chelate effect is (i.e., the preference for bi- versus monodentate binding modes of L), (ii) compare these ligands as a function of the chelate ring size, and (iii) assess the role of neutralizing counterions. For this purpose, we consider UO(2)L(2+), UO(2)L(2)(2+), UO(2)L(3)(2+), and UO(2)X(2)L type complexes with X(-) = Cl(-) versus NO(3)(-). Hartree-Fock and DFT calculations lead to similar trends and reveal the importance of saturation and steric repulsions ("strain") in the first coordination sphere. In the unsaturated UO(2)L(2+), UO(2)L(2)(2+), and UO(2)Cl(2)L complexes, the 7-ring chelate is preferred over the 6-ring chelate, and bidentate coordination is preferred over the monodentate one. However, in the saturated UO(2)(NO(3))(2)L complexes, the 6- and 7-chelating ligands have similar binding energies, and for a given ligand, the mono- and bidentate binding modes are quasi-isoenergetic. These conclusions are confirmed by the calculations of free energies of complexation in the gas phase. In condensed phases, the monodentate form of UO(2)X(2)L complexes should be further stabilized by coordination of additional ligands, as well as by interactions (e.g., hydrogen bonding) of the "free" carbonyl oxygen, leading to an enthalpic preference for this form, compared to the bidentate one. We also considered an isodesmic reaction exchanging one bidentate ligand L with two monoamide analogues, which reveals that the latter are clearly preferred (by 23-14 kcal/mol at the HF level and 24-12 kcal/mol at the DFT level). Thus, in the gas phase, the studied bidentate ligands are enthalpically disfavored, compared to bis-monodentate analogues. The contrast with trends observed in solution hints at the importance of "long range" forces (e.g., second shell interactions) and entropy effects on the chelate effect in condensed phases. PMID:12767210

  18. Predictors of dimercaptosuccinic acid chelatable lead and tibial lead in former organolead manufacturing workers

    PubMed Central

    Schwartz, B. S.; Stewart, W. F.; Todd, A. C.; Links, J. M.

    1999-01-01

    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

  19. Thermodynamic stability and relaxation studies of small, triaza-macrocyclic Mn(II) chelates.

    PubMed

    de Sá, Arsénio; Bonnet, Célia S; Geraldes, Carlos F G C; Tóth, Éva; Ferreira, Paula M T; André, João P

    2013-04-01

    Due to its favorable relaxometric properties, Mn(2+) is an appealing metal ion for magnetic resonance imaging (MRI) contrast agents. This paper reports the synthesis and characterization of three new triazadicarboxylate-type ligands and their Mn(2+) chelates (NODAHep, 1,4,7-triazacyclononane-1,4-diacetate-7-heptanil; NODABA, 1,4,7-triazacyclononane-1,4-diacetate-7-benzoic acid; and NODAHA, 1,4,7-triazacyclononane-1,4-diacetate-7-hexanoic acid). The protonation constants of the ligands and the stability constants of the chelates formed with Mn(2+) and the endogenous Zn(2+) ion have been determined by potentiometry. In overall, the thermodynamic stability of the chelates is lower than that of the corresponding NOTA analogues (NOTA = 1,4,7-triazacyclononane-1,4,7-triacetate), consistent with the decreased number of coordinating carboxylate groups. Variable temperature (1)H NMRD and (17)O NMR measurements have been performed on the paramagnetic chelates to provide information on the water exchange rates and the rotational dynamics. The values of the (17)O chemical shifts are consistent with the presence of one water molecule in the first coordination sphere of Mn(2+). The three complexes are in the slow to intermediate regime for the water exchange rate, and they all display relatively high rotational correlation times, which explain the relaxivity values between 4.7 and 5.8 mM(-1) s(-1) (20 MHz and 298 K). These relaxivities are higher than expected for Mn(2+) chelates of such size and comparable to those of small monohydrated Gd(3+) complexes. The amphiphilic [Mn(NODAHep)] forms micelles above 22 mM (its critical micellar concentration was determined by relaxometry and fluorescence), and interacts with HSA via its alkylic carbon chain providing a 60% relaxivity increase at 20 MHz due to a longer tumbling time. PMID:23348796

  20. Characterization of amorphous yttria layers deposited by aqueous solutions of Y-chelate alkoxides complex

    NASA Astrophysics Data System (ADS)

    Kim, Young-Soon; Lee, Yu-Ri; Kim, Byeong-Joo; Lee, Jae-Hun; Moon, Seung-Hyun; Lee, Hunju

    2015-01-01

    Crack-free amorphous yttria layers were deposited by dip coating in solutions of different Y-chelate alkoxides complex. Three Y-chelate solutions of different concentrations were prepared using yttrium acetate tetrahydrate, yttrium stearic acid as Y source materials. PEG, diethanolamine were used as chelating agents, while ethanol, methanol and tetradecane were used as solvent. Three different combinations of chelating and solvents were used to prepare solutions for Y2O3 dip coating on SUS, electropolished and non-electropolished Hastelloy C-276 substrates. The thickness of the films was varied by changing the number of dipping cycles. At an optimized condition, the substrate surface roughness (rms) value was reduced from ?50 nm to ?1 nm over a 10 × 10 ?m2 area. After Y2O3 deposition, MgO was deposited using ion-beam assisted deposition (IBAD), then LaMnO3 (LMO) was deposited using sputtering and GdBCO was deposited using reactive co-evaporation by deposition and reaction (RCE-DR). Detailed X-ray study indicates that LMO/MgO/Y2O3 and GdBCO/LMO/MgO/Y2O3 stack films have good out-of-plane and in-plane textures with strong c-axis alignment. The critical current (Ic) of GdBCO/LMO/MgO/Y2O3 multilayer structure varied from 190 to 420 A/cm with different solutions, when measured at 77 K. These results demonstrated that amorphous yttria can be easily deposited by dip coating using Y-chelates complex as a diffusion barrier and nucleation layer.