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Sample records for acid chelation phototherapeutic

  1. Copper, dioxouranium(VI) and lanthanide chelates of carboxymethylthiosuccinic acid

    Carboxymethylthiosuccinic acid (CMTSA) has three dissociable - COOH groups with pK values 2.91, 3.91, 5.03. Assignment of these values to the different carboxylic groups is given. Cu(II) and UO22+ chelates with CMSTA have been studied potentiometrically at 30degC and μ = 0.1M. The effects of dielectric constant of the solvent medium (dioxane-water) and the ionic strength, on these chelates have been examined. The lanthanides form 1:1 and 1:2 chelates with CMTSA. The plots of log K1 and (log K1 + log K2) versus e2/2r show a break at gadolinium. The thermodynamic parameters for these chelates have been determined. Smaller values of DELTAH show the predominance of the entropy effect in the formation of these chelates. (author)

  2. Mechanisms of oxide dissolution by acid chelating agents

    In this paper, the different possible rate controlling processes in the dissolution of metallic oxides are examined. In particular, the following situations are assessed: mass-transfer control; coupling of mass-transfer and reactions at the interface; interface equilibration with the solution; various interface disruption and reconstruction phenomena. For each of the above mentioned cases, the influence of variables such as reagent concentration, temperature, pH, fluid hydrodynamics and general and specific catalysts is discussed. Depending upon the particular situation it is found that a more rational basis for the development of reagent is given by these considerations. The influence of chelating agents on both the thermodynamics and kinetics of the process is discussed, and the results of experimental studies in batch on magnetite and various ferrites are presented and discussed. For this purpose, several reagents were studied, including some very effective ones like thioglycolic acid, and others commonly used in actual decontamination, like ethylenediaminetetraacetic acid and oxalic acid. The relation to other (reductive) chemical decontamination procedures is discussed. The relevance of these studies to decontamination of metallic surfaces is discussed

  3. Potentiometric studies on mixed-ligand chelates of uranyl ion with carboxylic acid phenolic acids

    Mixed ligand complexes of UO22+ with bidentate carboxylic and phenolic acids have been studied potentiometrically at 30 ± 0.1degC and μ=0.2M (NaClO4). 1:1 and 1:2 complexes of UO22+ with phthalic acid (PTHA), maleic acid (MAE), malonic acid (MAL), quinolinic acid (QA), 5-sulphosalicylic acid (5-SSA), salicylic acid (SA), and only 1:1 complexes in the case of mandelic acid (MAD) have been detected. The formation of 1:1:1 mixed ligand complexes has been inferred from simultaneous equilibria in the present study. The values of ΔlogK, Ksub(DAL), Ksub(2LA) or Ksub(2AL) for the ternary complexes have been calculated. The stabilities of mixed ligand complexes depend on the size of the chelate ring and the stabilities of the binary complexes. (author). 15 refs

  4. CATALYTIC HYDROGENATION OF ACRYLATE ASMMETRIC Dd(Ⅱ)—CHELATING RESINS CONTAINING AMINO ACID LIGANDS

    Wangying; WangHongzuo; 等

    1995-01-01

    The catalytic hydrogenation of palladium chelating resins containing chiral amino acid ligands based on lower crosslinked poly(chloroethyl acrylate) and some effects on the rate of hydrogenation were studied.

  5. Diglycolamic acid functionalized PAMAM-SDB chelating resin for removal of Th(IV) from aqueous and nitric acid medium

    Removal of radionuclides based on solid phase extraction (SPE) also known as solid-liquid extraction is developed considerably in the last few decades due to their simplicity, rapidity, easy operation and cost effectiveness. Various types of sorbents such as organic, inorganic, bio-sorbent, composites and carbon based material have been developed for the recovery of radionuclides. Among the solid sorbents, chelating resins are being increasingly used due to their high adsorption capacity and selectivity. The chelating resins are prepared either by impregnating or grafting the chelating agents on solid substrate. Generally, the adsorption efficiency depends on the type of chelating agent and to some extent on the size and physiochemical properties of the resin. Recovery of actinides from aqueous waste using chelating agent containing >P=O, >C=O or other functional groups of desired basicity and stereochemistry have been extensively studied. Removal of thorium from aqueous solution using diglycolamic acid (DGA) functionalized poly(amido)amine (PAMAM) dendron-styrene divinyl benzene (SDB) chelating resin is presented in this paper

  6. Chelation in metal intoxication X: influence of different polyaminocarboxylic acids and thiol chelators in the excretion and tissue distribution of 54Mn in rat

    The influence of some selected polyaminocarboxylic acids and thiol metal binding agents on the urinary and faecal excretions of 54Mn and on the tissue distribution of 54Mn in 54MnC12 administered rats was studied to find a suitable chelating drug for Mn poisoning. HEDTA, CDTA, DTPA and TTHA were highly successful in enhancing the excretion of 54Mn and reducing the tissue levels of 54Mn in rats. The thiol chelators viz. D L-penicillamine, N-acetyl D L-penicillamine and DMS could neither influence the excretion nor the tissue distribution of 54Mn suggesting poor affinity of the metal towards sulfhydryl groups

  7. Diethylentriaminepenta acetic acid glucose conjugates as a cell permeable iron chelator

    Mona Mosayebnia

    2014-01-01

    Full Text Available Objective: To find out whether DTPA-DG complex can enhance clearance of intracellular free iron. Materials and Methods: Diethylenetriaminepentaacetic acid-D-deoxy-glucosamine (DTPA-DG was synthesized and examined for its activity as a cell-permeable iron chelator in human hepatocellular carcinoma (HEPG2 cell line exposed to high concentration of iron sulfate and compared with deferoxamine (DFO, a prototype iron chelator. The effect of DTPA-DG on cell viability was monitored using the 3-(4,5-dimethythiazol-2-yl-2,5-diphenyl tetrazolium bromide MTT assay as well. Results: There was a significant increase of iron level after iron overload induction in HEPG2 cell culture. DTPA-DG presented a remarkable capacity to iron burden reducing with estimated 50% inhibitory concentration value of 65.77 nM. In fact, glycosyl moiety was gained access of DTPA to intracellular iron deposits through glucose transporter systems. Conclusion: DTPA-DG, more potent than DFO to sequester deposits of free iron with no profound toxic effect. The results suggest the potential of DTPA-DG in chelating iron and permitting its excretion from primary organ storage.

  8. Meso-2,3-dimercaptosuccinic acid: from heavy metal chelation to CdS quantum dots

    Sevinç, Esra; Ertaş, F. Sinem ; Ulusoy, Gülen ; Acar, Havva Yağcı; Özen, Can

    2012-01-01

    DMSA (meso-2,3-dimercaptosuccinic acid) a prescription drug and a heavy-metal chelating agent, is shown to act both as a sulfur source and a capping agent in the aqueous synthesis of CdS quantum dots under mild conditions. Release of sulfur from DMSA depends on the solution pH and the reaction temperature. Combination of 70 C and pH 7.5 was determined as the best reaction conditions for a well-controlled reaction. Changing the SH/Cd ratio from 2.5 to 7 provides QDs emitting from ...

  9. High-performance chelation chromatography of metal ions on sorbents with grafted iminodiacetic acid

    Chromatographic behavior of some alkaline earth, transition, heavy (including uranium) and rare earth metal ions on a group of complexing sorbents, containing surface functional groups of imidodiacetic acid, was studied. Conditions, under which metal retention is determined by complexing on the sorbent surface, were defined and main principles of a new variant of liquid chromatography, i.e. high-performance chelating chromatography of metal ions (HPCCI) were formulated. It is shown that under optimal conditions metal retention correlates linearly in bilogarithmic coordinates with stability constants of the relevant metal complexes. Potentialities of HPCCI analytic application to analysis of objects featuring complex composition were considered

  10. Fast removal of heavy metal ions and phytic acids from water using new modified chelating fiber

    Li Xu; Jin Nan Wang; Ying Meng; Ai Min Li

    2012-01-01

    The graft copolymerization of acrylic acid (AA) onto polyethylene glycol terephthalate (PET) fiber initiated by benzoy peroxide (BPO) was carried out in heterogeneous media.Moreover,modification of the grafted PET fiber (PET-AA) was done by changing the carboxyl group into acylamino group through the reaction with dimethylamine.The modified chelating fiber (NDWJN 1) was characterized using elementary analysis,SEM and FT-IR spectroscopy.Adsorption kinetic curves indicated that NDWJN1 could fast remove heavy metal ions and phytic acids from water effectively.Furthermore,batch kinetic studies indicated that heavy metal ions adsorbed to NDWJN1 could be fitted well by both pseudo-first-order and pseudo-second-order adsorption equations,but the intra-particle diffusion plaved a dominant role in the adsorption of phvtic acids.

  11. New method for studying the efficiency of chelating agents of the polyamine acid series for internal decontamination

    We followed the biological fate of a complex formed on one side with either a rare earth (cerium-144) or a transuranium element (plutonium-239), and on the other side with a chelating agent of the polyamino acid series (EDTA, BAETA, DTPA, TTHA). This method allowed to study: 1 - the in vivo stability of the various complexes and to compare them; 2 - the stability of the complexes as a function of the isotope - chelating agent weight relationships; 3 - the metabolism of the chelating agents resulting in stable complexes, i. e. DTPA and TTHA mainly. This simple method brought out the higher efficiency, of DTPA in chelating rare earths and plutonium and for therapeutic purposes. (authors)

  12. Chelation Properties of Modified Humic Acids Toward Some Trivalent Lanthanide Ions

    Three kinds of humic acids, Fluka (I), Fluka (II), and Ega-chemie (III) were modified through condensation with formaldehyde to afford polymers I, II, and III, respectively. The chelation behavior of these modified humic acids polymers towards the trivalent lanthanide metal-ions, La3+, Ce3+, Nd3+, Sm3+, and Gd3+ was studied by a batch equilibration technique at 25 deg. C as a function of contact time, pH, counter ion and counter ion concentration. The highest metal-ion uptake of the three polymers was achieved at pH 7.0 and by using perchlorate as a counter ion. Results of the study have revealed that polymer II has the highest metal-ion uptake capacity, and that the metal-ion uptake falls in the order: Gd3+ > Sm3+ > Nd3+ > La3+ ≅ Ce3+

  13. Separation of radiostrontium from alkaline reprocessing waste solution using a fixed-bed column of chelating iminodiacetic acid resin

    A fixed-bed ion exchange column filled with a chelating resin containing iminodiacetic acid functional groups has been tested for removal of strontium from simulated alkaline reprocessing waste solution. The breakthrough curve has been established. Column loading performance is correlated with batch equilibration results. The loaded strontium is eluted in a small volume of 0.5 M HNO3. (author)

  14. Novel phototherapeutic agents: Investigation and progress of hypocrellin derivatives

    XU Shangjie; ZHANG Xiaoxing; CHEN Shen; ZHANG Manhua; SHEN Tao; WANG Zhengping

    2003-01-01

    Hypocrellins, as a kind of novel phototherapeutic agents, have severaladvantages over the clinically used hematoporphyrin derivatives, including high-excited triplet state yield, high phototoxicity, low dark toxicity, and rapid metabolism. However, they exhibit little absorption in the photodynamic window (600-900 nm) and are not water soluble, which limits their application in photodynamic therapy. Sulfonated and metal-ioned hypocrellins have been designed and synthesized to improve their water solubility. Unfortunately, the water-soluble derivatives obtained exhibit lower photodynamic activity than the parent hypocrellins. Thiolated and aminated hypocrellins have also been designed and synthesizedto enlarge their photoresponse. Among them, the aminated hypocrellins possess the highest photodynamic activity. We recently have further designed and synthesized some amphiphilic aminated hypocrellin derivatives. Thus, not only the photoresponse but also the water solubility is enhanced. The experiments in vitro and in vivo on the derivatives are under way at present.

  15. A new chelating ion-exchanger containing p-bromophenylhydroxamic acid as functional group

    A new chelating resin based on macroreticular acrylonitrile-divinylbenzene copolymer and containing hydroxamic acid functional groups has been synthesized. It is highly-stable in acidic and alkaline solutions. The sorption characteristics of Cu(II), Cd(II), Pb(II), Zn(II), U(VI), Cr(VI), V(V), Co(II), Ni(II), Ca(II) and Mg(II) have been investigated over the pH range 1.0-6.0. The effect of various electrolytes at different ionic strengths on the Ksub(d) values for Cu(II), Cd(II), Pb(II) and Zn(II) has been studied systematically. Chromatographic separations of copper(II) and nickel(II) from cobalt(II), and of uranium(VI) from chromium(VI) by selective sorption at controlled pH, have been developed. The ion-exchanger can be used for purification of inorganic salts, and analysis of brass and bauxite. (author)

  16. Effects of chelating agents on protein, oil, fatty acid amd seed mineral concentrations in soybean

    Soybean seed is a major source of protein and oil for human diet. Since not much information is available on the effects of chelating agents on soybean seed composition constituents, the current study aimed to investigate the effects of various chelating agents on soybean [(Glycine max (L.) Merr.)] ...

  17. Stereoselective analysis of D and L dansyl amino acids as the mixed chelate copper(II) complexes by HPLC.

    Lam, S

    1984-09-01

    This paper reviews the mixed chelation approach to resolution of the optical isomers of D and L dansyl amino acids by high performance liquid chromatography. The use of eluants containing Cu(II) complexes of L-proline, L-arginine, L-histidine, and L-histidine methyl ester effected the separation of many D and L amino acids, including those with aliphatic, polar, and aromatic substituents. The mechanism of separation, which is based on the preferential ternary complex formation of the analyte amino acid and the chiral chelate with Cu(II) in the mobile phase, is discussed. The stereoselectivity depends mainly on the different steric interactions between the alkyl side chains of the amino acid analytes and the chiral ligands coordinating around Cu(II), although such parameters as pH, temperature, organic modifier, and concentration of the chiral additive also affect the chromatographic separation. Among the chiral ligands studied, L-histidine methyl ester is unique in that it possesses both achiral selectivity for the dansyl amino acids and chiral selectivity for the respective D and L enantiomers. With a mobile phase gradient of acetonitrile in a buffer containing Cu(II) L-histidine methyl ester complex, a stereoselective procedure was devised for the analysis of D and L amino acid enantiomers, achieving the separation that the current amino acid analyzer could not perform. Finally, the use of the mixed chelation approach in two biomedical studies is described. In the first application, the histidine methyl ester gradient was adapted for analyzing amino acids in cerebrospinal fluid; in the second, an L-aspartame Cu(II) complex eluant was developed for measuring the urine concentration of D and L pipecolic acid (piperidine-2-carboxylic acid), a metabolite of lysine. PMID:6490790

  18. Correlation of acid-base properties of substituted polystyrene-azo-pyrocatechol and characteristics of their chelates with zirconium

    Acid-base and complexing properties of new synthesized polymeric chelate-forming sorbents (PCS) - substituents of polystyrene-azo-pyrocatechol - are investigated and quantitative correlations between pKOH of functional analytical group (FAG) of sorbent and Hammet constants for para-substituent and ΔpKOH-ΔpK50 correlations of zirconium chelate-forming and pKOH-lgKstb (Kstb - constant of stability of PCS complexes with zirconium) of polychelates to study regularities of effect of peculiarities of structure and acid-base properties of FAG on parameters of zirconium chemical sorption. Established correlations make it possible to predict quantitative physicochemical parameters of sorbents and zirconium chemisorption process with the aim of directed synthesis and application of PCS in concentrating processes

  19. Phototherapeutic treatment of lymphedema and other complications after mastectomy

    Zharov, Vladimir P.; Kalinin, Konstantin L.; Borisov, Andrei A.; Velsher, Leonid Z.; Stakhanov, Mikhail L.; Eskin, Vadim G.; Savin, Alexei A.; Shihkerimov, Raphiz K.

    2000-05-01

    One of the possible consequences of mastectomy is lymphedema of soft tissues of upper extremities on the side of ablated breast as result of cutting and trauma of multiple nerves, lymphatic and blood vessels. This phenomenon is often accompanied by deterioration of blood and lymphatic microcirculation, increasing of stagnation and aggregation ability of thrombocities, limitation of humeral and ulnar joint activity, severe pain and decreasing of myotonus. The developing of new phototherapeutic method based on using of light-emitting diodes (LED) arrays is attempted. This method is just directed on improvement of patient's condition in combination with other traditional methods such as drug therapy, pressure bandaging etc. The main parameters of LED arrays fixed inside cylindrical tube covering pathology region are: wavelength -- 660 nm, intensity range -- 0.5 mW/sm2. To control and study efficiency of phototreatment ultrasonic dopplerography, thermography, electromyography and viscosimetry have been used. During clinical trials in oncology department of Moscow State University of Medicine and Dentistry 128 patients have been treated with following results: patients felt complete disappearance of pain and weightiness sensation in arm, restoration of skin sensitivity and muscle strength. There were statistically proved amelioration of excitation spreading velocity on radial nerve, decreasing of blood viscosity, increasing of blood velocity in main arteries of shoulder and symmetry of temperature distribution.

  20. Macrocyclic bifunctional chelating agents

    Meares, Claude F.; DeNardo, Sally J.; Cole, William C.; Mol, Min K.

    1987-01-01

    A copper chelate conjugate which is stable in human serum. The conjugate includes the copper chelate of a cyclic tetraaza di-, tri-, or tetra-acetic acid, a linker attached at one linker end to a ring carbon of the chelate, and a biomolecule joined at the other end of the linker. The conjugate, or the linker-copper chelate compound used in forming the conjugate, are designed for use in diagnostic and therapeutic applications which involve Cu(II) localization via the systemic route.

  1. Release of cetyl pyridinium chloride from fatty acid chelate temporary dental cement

    Hurt, Andrew; Coleman, Nichola J.; Tüzüner, Tamer; Bagis, Bora; Korkmaz, Fatih Mehmet; Nicholson, John W.

    2016-01-01

    Abstract Objective To determine whether the antimicrobial nature of a fatty acid chelate temporary dental cement can be enhanced by the addition of 5% cetyl pyridinium chloride (CPC). Materials and methods The temporary cement, Cavex Temporary was employed, and additions of CPC were made to either the base or the catalyst paste prior to mixing the cement. Release of CPC from set cement specimens was followed using reverse-phase HPLC for a period of up to 2 weeks following specimen preparation. Potential interactions between Cavex and CPC were examined by Fourier transform infrared spectroscopy (FTIR) and antimicrobial effects were determined using zone of inhibition measurements after 24 h with disc-shaped specimens in cultured Streptococcus mutans. Results FTIR showed no interaction between CPC and the components of the cement. CPC release was found to follow a diffusion mechanism for the first 6 h or so, and to equilibrate after approximately 2 weeks, with no significant differences between release profiles when the additive was incorporated into the base or the catalyst paste. Diffusion was rapid, and had a diffusion coefficient of approximately 1 × 10−9 m2 s−1 in both cases. Total release was in the range 10–12% of the CPC loading. Zones of inhibition around discs containing CPC were significantly larger than those around the control discs of CPC-free cement. Conclusions The antimicrobial character of this temporary cement can be enhanced by the addition of CPC. Such enhancement is of potential clinical value, though further in vivo work is needed to confirm this. PMID:27335898

  2. Nitrogen-doped carbon nanofoam derived from amino acid chelate complex for supercapacitor applications

    Ramakrishnan, Prakash; Shanmugam, Sangaraju

    2016-06-01

    We report a novel strategy to fabricate the nitrogen-doped mesoporous carbon nanofoam structures (N-MCNF), derived from magnesium amino acid chelate complex (Mg-acc-complex) for its application towards high performance supercapacitor (SCs) system. A series of N-MCNF with well-connected carbon nanofoam structure have been developed by varying the synthesis temperature. The fabricated N-MCNF material possesses a high surface area (1564 m2 g-1) and pore volume (1.767 cm3 g-1) with nitrogen content of 3.42 wt%. A prototypical coin cell type symmetric N-MCNF SC device has been assembled with 1-ethyl-3-methylimidazolium tetrafluoroborate [EMIMBF4] ionic liquid electrolyte, and evaluated for SCs studies. The N-MCNF with high textural properties delivers unprecedented SC performance, such as high specific capacitance (204 Fg-1 at 0.25 Ag-1, 25 °C), high energy density (63.4 Wh kg-1), high power density (35.9 kW kg-1) and long-term cycle life (32,500 cycles). Significantly, N-MCNF materials exhibited high power rate performance, at 500 mV-1 (115 Fg-1) and 25 Ag-1 (166 Fg-1) owing to the uniform mesopore size distribution (∼4 nm). The N-MCNF SC device delivered maximum energy densities of 83.4 and 93.3 Wh kg-1 at 60 °C and 90 °C, respectively. Such outstanding N-MCNF SC device is successfully demonstrated in solar energy harvester applications.

  3. Enteric-coated tablet of risedronate sodium in combination with phytic acid, a natural chelating agent, for improved oral bioavailability.

    Kim, Jeong S; Jang, Sun W; Son, Miwon; Kim, Byoung M; Kang, Myung J

    2016-01-20

    The oral bioavailability (BA) of risedronate sodium (RS), an antiresorptive agent, is less than 1% due to its low membrane permeability as well as the formation of non-absorbable complexes with multivalent cations such as calcium ion (Ca(2+)) in the gastrointestinal tract. In the present study, to increase oral BA of the bisphosphonate, a novel enteric-coated tablet (ECT) dosage form of RS in combination with phytic acid (IP6), a natural chelating agent recognized as safe, was formulated. The chelating behavior of IP6 against Ca(2+), including a stability constant for complex formulation was characterized using the continuous variation method. Subsequently, in vitro dissolution profile and in vivo pharmacokinetic profile of the novel ECT were evaluated comparatively with that of the marketed product (Altevia, Sanofi, US), an ECT containing ethylenediaminetetraacetic acid (EDTA) as a chelating agent, in beagle dogs. The logarithm of stability constant for Ca(2+)-IP6 complex, an equilibrium constant approximating the strength of the interaction between two chemicals to form complex, was 19.05, which was 3.9-fold (p<0.05) and 1.7-fold (p<0.05) higher than those of Ca(2+)-RS and Ca(2+)-EDTA complexes. The release profile of RS from both enteric-coated dosage forms was equivalent, regardless of the type of chelating agent. An in vivo absorption study in beagle dogs revealed that the maximum plasma concentration and area under the curve of RS after oral administration of IP6-containing ECT were approximately 7.9- (p<0.05) and 5.0-fold (p<0.05) higher than those of the marketed product at the same dose (35mg as RS). Therefore, our study demonstrates the potential usefulness of the ECT system in combination with IP6 for an oral therapy with the bisphosphonate for improved BA. PMID:26594027

  4. Organic acids rather than histidine predominate in Ni chelation in Alyssum hyperaccumulator xylem exudate

    A better understanding of Ni uptake mechanisms by hyperaccumulator plants is necessary to improve Ni uptake efficiency for phytoremediation technologies i.e. phytomining. It is known that an important aspect of Ni translocation involves Ni chelation with organic ligands. However, it is still not cle...

  5. Chelatization of Metals Ion (Cu2+, Cd2+ and Cr3+) with ProcessYield of Humic Acid from Peat Soil

    The chelation of metals ion (Cu2+, Cd2+ and Cr3+) with processyields of humic acid from peat soil has been done. The chelatizationcalculation was carried out using a mathematical model of the metals ionneutralization to the humic acid functional group. The model has superioritydue to the introduction of the humic acid concentration conditional and theloading capacity. Chelation is expected to obtain the constant experimentthat agrees with environmental conditional were the chelatization to takeplaces. By the tree neck flask of bath reactor, 250 ml volume at thetemperature of 25 oC chelation have been done and the AAS was used toanalyzes the yield. By mathematical calculate was obviously proved that thechelation constants was not influenced by pH, ionic strength and origin peatsoils. As log β, chelation constants of Cu2+, Cd2+ and Cr3+ were4.67 (± 0.02); 5.98 (± 0.02) and 6.09 (± 0.01) for humic acid fromSumatra I (Silaut III) and 4.68 (± 0.01); 5.97 (± 0.02) and 6.09 (±0.02) for Sumatra II (Silaut IV). While chelation constant Cu2+, Cd2+ andCr3+ from Kalimantan were 4.66 (± 0.03); 5.99 (± 0.01); 6.08 (±0.02). (author)

  6. Results of the Application of Phototherapeutic Keratectomy in the Elderly with Bullous Keratopathy

    Osbel Alfonso Sánchez

    2012-11-01

    Full Text Available Background: Many countries have conducted studies on the benefits of phototherapeutic keratectomy in corneal diseases; few references have been found in our country to address the results of the application of the excimer laser in the elderly suffering from bullous keratopathy. Objective: To assess the results of the application of phototherapeutic keratectomy in the eldrly with bullous keratopathy. Methods: A case series study was conducted in 2009, in the Cornea Department of the Dr. Gustavo Aldereguía Lima General University Hospital of Cienfuegos. It included 16 elderly with bullous keratopathy not leading to penetrating keratoplasty. After considering the ethical and biomedical assessment, phototherapeutic keratectomy was performed. Treatment was indicated and follow up was performed with an assessment of symptoms and signs until the third month. Results: In the postoperative stage symptoms decreased and the most frequent sign was the haze followed by slight increase in best corrected visual acuity. Conclusions: The application of phototherapeutic keratectomy in patients that did not apply for cornea transplant helps improving eye condition, reduces symptoms and improves visual acuity.

  7. IMPACT OF ACID WASHING AND CHELATION ON Mg(OH2-BASED HYDROGEN PEROXIDE BLEACHING OF MIXED HARDWOODS CMP AT A HIGH CONSISTENCY

    Somayeh Ghasemi

    2010-09-01

    Full Text Available The removal of transition metal ions is crucial for improving the efficiency of subsequent peroxide bleaching. Acid-washing and chelation have been proposed for such a purpose. However, their influences on the Mg(OH2-based peroxide bleaching of hardwood pulps at a high consistency have not been well documented in the literature. In this work, we studied the influence of acid-washing using sulfuric acid or chelation using diethylenetriaminepentaacetic (DTPA on the Mg(OH2- or NaOH-based hydrogen peroxide bleaching efficiency, effluent properties of bleaching filtrates, and paper properties. The results showed that for Mg(OH2-based peroxide bleaching, the pulp yield and water retention value of acid-washed pulp were higher than those of the chelated pulp; the chemical oxygen demand (COD and turbidity of the bleaching filtrates for the acid-washed pulp were lower than those of the chelated pulp. The bleached acid-washed pulp had lower strength properties than bleached chelated pulp did. Additionally, at a high pulp consistency (25%, the Mg(OH2-based process had a higher bleaching efficiency and superior bleaching effluent properties, but a lower strength properties, in comparison with the NaOH-based process.

  8. Chelating agents related to ethylenediamine bis(2-hydroxyphenyl)acetic acid (EDDHA): synthesis, characterization, and equilibrium studies of the free ligands and their Mg2+, Ca2+, Cu2+, and Fe3+ chelates.

    Yunta, Felipe; García-Marco, Sonia; Lucena, Juan J; Gómez-Gallego, Mar; Alcázar, Roberto; Sierra, Miguel A

    2003-08-25

    Iron chelates such as ethylenediamine-N,N'-bis(2-hydroxyphenyl)acetic acid (EDDHA) and their analogues are the most efficient soil fertilizers to treat iron chlorosis in plants growing in calcareous soils. EDDHA, EDDH4MA (ethylenediamine-N,N'-bis(2-hydroxy-4-methylphenyl)acetic acid), and EDDCHA (ethylenediamine-N,N'-bis(2-hydroxy-5-carboxyphenyl)acetic acid) are allowed by the European directive, but also EDDHSA (ethylenediamine-N,N'-bis(2-hydroxy-5-sulfonylphenyl)acetic acid) and EDDH5MA (ethylenediamine-N,N'-bis(2-hydroxy-5-methylphenyl)acetic acid) are present in several commercial iron chelates. In this study, these chelating agents as well as p,p-EDDHA (ethylenediamine-N,N'-bis(4-hydroxyphenyl)acetic acid) and EDDMtxA (ethylenediamine-N,N'-bis(2-metoxyphenyl)acetic acid) have been obtained following a new synthetic pathway. Their chemical behavior has been studied to predict the effect of the substituents in the benzene ring on their efficacy as iron fertilizers for soils above pH 7. The purity of the chelating agents has been determined using a novel methodology through spectrophotometric titration at 480 nm with Fe(3+) as titrant to evaluate the inorganic impurities. The protonation constants were determined by both spectrophotometric and potentiometric methods, and Ca(2+) and Mg(2+) stability constants were determined from potentiometric titrations. To establish the Fe(3+) and Cu(2+) stability constants, a new spectrophotometric method has been developed, and the results were compared with those reported in the literature for EDDHA and EDDHMA and their meso- and rac-isomers. pM values have been also determined to provide a comparable basis to establish the relative chelating ability of these ligands. The purity obtained for the ligands is higher than 87% in all cases and is comparable with that obtained by (1)H NMR. No significant differences have been found among ligands when their protonation and stability constants were compared. As expected, no Fe(3

  9. A dual chelating sol–gel synthesis of BaTiO{sub 3} nanoparticles with effective photocatalytic activity for removing humic acid from water

    Wang, Peigong [College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Fan, Caimei, E-mail: fancm@163.com [College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Wang, Yawen; Ding, Guangyue; Yuan, Peihong [College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024 (China)

    2013-02-15

    Graphical abstract: The cubic phase BaTiO{sub 3} nanoparticles can be obtained at 600 °C and changed into tetragonal phase at 900 °C by a dual chelating sol–gel method, and the photocatalytic activities of the photocatalysts calcined at different temperatures were investigated by the removal of humic acid (HA) from water under UV light irradiation. Highlights: ► The humic acid in water was firstly degradated by BaTiO{sub 3} photocatalyst. ► The cubic BaTiO{sub 3} was obtained and changed into tetragonal phase at lower temperature. ► The chelating agents had an important influence on the phase formation of BaTiO{sub 3}. ► The tetragonal phase BaTiO{sub 3} calcined at 900 °C exhibited higher photocatalytic activity under UV irradiation. -- Abstract: In this paper, a dual chelating sol–gel method was used to synthesize BaTiO{sub 3} nanoparticles by using acetylacetone and citric acid as chelating agents. The samples calcined at different temperatures were analyzed by thermogravimetric and differential thermal analysis (TG-DTA), X-ray diffraction (XRD), X-ray photoelectron spectra (XPS), scanning electron microscope (SEM) and UV–vis diffuse reflectance spectra (UV–vis). The results indicated that cubic phase BaTiO{sub 3} nanoparticles about 19.6 nm can be obtained at 600 °C and changed into tetragonal phase at 900 °C about 97.1 nm. All the BaTiO{sub 3} nanoparticles showed effective photocatalytic activities on the removal of humic acid (HA) under UV light irradiation. A comparison of single (acetylacetone or citric acid) and dual chelating (acetylacetone and citric acid) synthetic processes was also studied and the results demonstrated that the dual chelating agents indeed reduced phase transformation temperature from cubic to tetragonal BaTiO{sub 3}.

  10. Benzyl and Methyl Fatty Hydroxamic Acids Based on Palm Kernel Oil as Chelating Agent for Liquid-Liquid Iron(III) Extraction

    Jamileh Amin; Roshanak Rafiee-Moghaddam; Behnam Mahdavi; Mazyar Peyda; Anuar Kassim; Nor Azah Yusof; Md Jelas Haron; Hossein Jahangirian; Yadollah Abdollahi; Sidik Silong

    2012-01-01

    Liquid-liquid iron(III) extraction was investigated using benzyl fatty hydroxamic acids (BFHAs) and methyl fatty hydroxamic acids (MFHAs) as chelating agents through the formation of iron(III) methyl fatty hydroxamate (Fe-MFHs) or iron(III) benzyl fatty hydroxamate (Fe-BFHs) in the organic phase. The results obtained under optimized conditions, showed that the chelating agents in hexane extract iron(III) at pH 1.9 were realized effectively with a high percentage of extraction (97.2% and 98.1%...

  11. Paramagnetic relaxation enhancement of membrane proteins by incorporation of the metal-chelating unnatural amino acid 2-amino-3-(8-hydroxyquinolin-3-yl)propanoic acid (HQA)

    Park, Sang Ho; Wang, Vivian S.; Radoicic, Jasmina; Angelis, Anna A. De; Berkamp, Sabrina; Opella, Stanley J., E-mail: sopella@ucsd.edu [University of California, San Diego, Department of Chemistry and Biochemistry (United States)

    2015-04-15

    The use of paramagnetic constraints in protein NMR is an active area of research because of the benefits of long-range distance measurements (>10 Å). One of the main issues in successful execution is the incorporation of a paramagnetic metal ion into diamagnetic proteins. The most common metal ion tags are relatively long aliphatic chains attached to the side chain of a selected cysteine residue with a chelating group at the end where it can undergo substantial internal motions, decreasing the accuracy of the method. An attractive alternative approach is to incorporate an unnatural amino acid that binds metal ions at a specific site on the protein using the methods of molecular biology. Here we describe the successful incorporation of the unnatural amino acid 2-amino-3-(8-hydroxyquinolin-3-yl)propanoic acid (HQA) into two different membrane proteins by heterologous expression in E. coli. Fluorescence and NMR experiments demonstrate complete replacement of the natural amino acid with HQA and stable metal chelation by the mutated proteins. Evidence of site-specific intra- and inter-molecular PREs by NMR in micelle solutions sets the stage for the use of HQA incorporation in solid-state NMR structure determinations of membrane proteins in phospholipid bilayers.

  12. Paramagnetic relaxation enhancement of membrane proteins by incorporation of the metal-chelating unnatural amino acid 2-amino-3-(8-hydroxyquinolin-3-yl)propanoic acid (HQA)

    The use of paramagnetic constraints in protein NMR is an active area of research because of the benefits of long-range distance measurements (>10 Å). One of the main issues in successful execution is the incorporation of a paramagnetic metal ion into diamagnetic proteins. The most common metal ion tags are relatively long aliphatic chains attached to the side chain of a selected cysteine residue with a chelating group at the end where it can undergo substantial internal motions, decreasing the accuracy of the method. An attractive alternative approach is to incorporate an unnatural amino acid that binds metal ions at a specific site on the protein using the methods of molecular biology. Here we describe the successful incorporation of the unnatural amino acid 2-amino-3-(8-hydroxyquinolin-3-yl)propanoic acid (HQA) into two different membrane proteins by heterologous expression in E. coli. Fluorescence and NMR experiments demonstrate complete replacement of the natural amino acid with HQA and stable metal chelation by the mutated proteins. Evidence of site-specific intra- and inter-molecular PREs by NMR in micelle solutions sets the stage for the use of HQA incorporation in solid-state NMR structure determinations of membrane proteins in phospholipid bilayers

  13. Chelation in metal intoxication XXX: α-mercapto-β-aryl acrylic acids as antidotes to cadmium toxicity

    α-Mercapto-β-(2-furyl) acrylic acid (MFA), α-mercapto-β-(2-hydroxyphenyl) acrylic acid (MHA), β-1,2-phenylene di-α-mercaptoacrylic acid (1,2-PDMA) and β-l,4-phenylene di-α-mercapto acrylic acid (1,4-PDMA) were compared to sodium N-benzyl-D-glucamine dithiocarbamate (NBG-DTC) an effective cadmium chelator, for their ability to mobilize Cd and influence the Cd induced tissue metallothionein (MT) in rats administered 109CdCl2, 72 hr earlier. MFA was almost as effective as NBG-DTC but more effective than MHA in enhancing urinary and faecal excretion of Cd, reducing tissue and blood levels of Cd and in lowering Cd induced increase in hepatic and renal MT contents. 1,2-PDMA and l,4-PDMA were effective only in reducing the hepatic burden of Cd. The results do not indicate any direct relationship between the efficacy of α-mercapto-β-aryl acrylic acids to decorporate body Cd and their lipophilic-hydrophilic character or number-arrangement of their sulfhydryl groups. (author)

  14. Preservation of glutamic acid-iron chelate into montmorillonite to efficiently degrade Reactive Blue 19 in a Fenton system under sunlight irradiation at neutral pH

    Huang, Zhujian; Wu, Pingxiao; Gong, Beini; Yang, Shanshan; Li, Hailing; Zhu, Ziao; Cui, Lihua

    2016-05-01

    To further enhance the visible light responsive property and the chemical stability of Fe/clay mineral catalysts, glutamic acid-iron chelate intercalated montmorillonite (G-Fe-Mt) was developed. The physiochemical properties of G-Fe-Mt were investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (DRS), etc. The results showed that glutamic acid-iron chelates were successfully intercalated into the gallery of montmorillonite and the intercalated glutamic acid-iron chelate molecules were well preserved. The product G-Fe-Mt displayed excellent catalytic performance in heterogeneous photo-Fenton reaction under sunlight irradiation at acidic and neutral pH values. The chelation and the visible light responsiveness of glutamic acid produce a synergistic effect leading to greatly enhanced sunlight-Fenton reaction catalyzed by the heterogeneous G-Fe-Mt under neutral pH. G-Fe-Mt is a promising catalyst for advanced oxidation processes.

  15. Programmed activation of cancer cell apoptosis: A tumor-targeted phototherapeutic topoisomerase I inhibitor

    Shin, Weon Sup; Han, Jiyou; Kumar, Rajesh; Lee, Gyung Gyu; Sessler, Jonathan L.; Kim, Jong-Hoon; Kim, Jong Seung

    2016-07-01

    We report here a tumor-targeting masked phototherapeutic agent 1 (PT-1). This system contains SN-38—a prodrug of the topoisomerase I inhibitor irinotecan. Topoisomerase I is a vital enzyme that controls DNA topology during replication, transcription, and recombination. An elevated level of topoisomerase I is found in many carcinomas, making it an attractive target for the development of effective anticancer drugs. In addition, PT-1 contains both a photo-triggered moiety (nitrovanillin) and a cancer targeting unit (biotin). Upon light activation in cancer cells, PT-1 interferes with DNA re-ligation, diminishes the expression of topoisomerase I, and enhances the expression of inter alia mitochondrial apoptotic genes, death receptors, and caspase enzymes, inducing DNA damage and eventually leading to apoptosis. In vitro and in vivo studies showed significant inhibition of cancer growth and the hybrid system PT-1 thus shows promise as a programmed photo-therapeutic (“phototheranostic”).

  16. Chelation in metal intoxication

    Aaseth, Jan; Skaug, Marit Aralt; Cao, yang;

    2015-01-01

    The present review provides an update of the general principles for the investigation and use of chelating agents in the treatment of intoxications by metals. The clinical use of the old chelators EDTA (ethylenediamine tetraacetate) and BAL (2,3-dimercaptopropanol) is now limited due to the...... inconvenience of parenteral administration, their own toxicity and tendency to increase the neurotoxicity of several metals. The hydrophilic dithiol chelators DMSA (meso-2,3-dimercaptosuccinic acid) and DMPS (2,3-dimercapto-propanesulphonate) are less toxic and more efficient than BAL in the clinical treatment...... of heavy metal poisoning, and available as capsules for oral use. In copper overload, DMSA appears to be a potent antidote, although d-penicillamine is still widely used. In the chelation of iron, the thiols are inefficient, since iron has higher affinity for ligands with nitrogen and oxygen, but the...

  17. Chelation of some transitions, lanthanides and uranium elements with nitrilotriacetic acid and radiolysis of their aqueous solutions

    The present thesis contains chelation studies of some transition metal ions (iron fe (III), cobalt Co (II) and nickel Ni (II), trivalent lanthanide ions (praseodymium pr(III) neodymium nd (III), samarium sm(III), europium Eu(III), gadolinium Gd (III), dysprosium dy (III), erbium Er(III) and ytterbium Yb(III) and uranium (U(IV) and U (V I)) with nitrilotriacetic acid (NTA). spectrophotometric techniques are used to investigate the effectiveness of NTA as a decontaminating agent for radioactive nuclides and to evaluate the optimum conditions under which stable and soluble complexes can be formed. these studies include the effect of PH on the formed complexes and determination of stability constants of the formed species. potentiometric analysis are also performed to follow the formation of binary complexes of some sulpha drugs with investigated metal ions and mixed ligand complexes arising to determine their formation constants

  18. Programmed activation of cancer cell apoptosis: A tumor-targeted phototherapeutic topoisomerase I inhibitor

    Weon Sup Shin; Jiyou Han; Rajesh Kumar; Gyung Gyu Lee; Sessler, Jonathan L.; Jong-Hoon Kim; Jong Seung Kim

    2016-01-01

    We report here a tumor-targeting masked phototherapeutic agent 1 (PT-1). This system contains SN-38—a prodrug of the topoisomerase I inhibitor irinotecan. Topoisomerase I is a vital enzyme that controls DNA topology during replication, transcription, and recombination. An elevated level of topoisomerase I is found in many carcinomas, making it an attractive target for the development of effective anticancer drugs. In addition, PT-1 contains both a photo-triggered moiety (nitrovanillin) and a ...

  19. Regeneration of Three-Way Automobile Catalysts using Biodegradable Metal Chelating Agent – S, S-Ethylenediamine Disuccinic Acid (S, S-EDDS)

    Regeneration of the activity of three-way catalytic converters (TWCs) was tested for the first time using a biodegradable metal chelating agent (S, S. Ethylenediamine disuccinic acid (S, S-EDDS). The efficiency of this novel environmentally friendly solvent in removing various c...

  20. Heavy metal removal from sludge with organic chelators: Comparative study of N, N-bis(carboxymethyl) glutamic acid and citric acid.

    Suanon, Fidèle; Sun, Qian; Dimon, Biaou; Mama, Daouda; Yu, Chang-Ping

    2016-01-15

    The applicability and performance of a new generation of biodegradable chelator, N, N-Bis(carboxymethyl) glutamic acid (GLDA), for extracting heavy metals from sewage sludge was carried out and compared with citric acid (CA). Targeted metals included Cd, Co, Cu, Zn, Ni and Cr, and their contents in the raw sludge were 63.1, 73.4, 1103.2, 2060.3, 483.9 and 604.1 mg kg(-1) (dry sludge basis), respectively. Metals were divided into six fractions including water soluble, exchangeable, carbonates bound, Fe-Mn bound, organic matters bound and residual fraction via chemical fractionation. Washing results showed that in general GLDA exhibited better performance compared with CA, with removal efficiency of 83.9, 87.3, 81.2, 85.6, 89.3 and 90.2% for Cd, Co, Cu, Zn, Ni and Cr, respectively at equilibrium pH = 3.3. Residual metals were better stabilized in the GLAD-washed sludge than in the CA-washed sludge, and were mostly tightly bonded to the residual fraction. Furthermore, CA promoted phosphorus (P) release while GLDA had an opposite effect and tended to retain P within sludge, which could be beneficial for further application in agricultural use. Findings from this study suggested that GLDA could be a potential replacement for refractory and less environmentally-friendly chelators in the extraction of metals from sludge. PMID:26520041

  1. SYNTHESES AND ADSORPTION PROPERTIES OF PHENOL-FORMALDEHYDE TYPE CHELATING RESINS BEARING THE FUNCTIONAL GROUP OF TARTARIC ACID

    Rong-jun Qu; Chun-nuan Ji; Yan-zhi Sun; Zhong-fang Li; Guo-xiang Cheng; Ren-feng Song

    2004-01-01

    Several kinds of novel chelating resins bearing the functional group of tartaric acid (TTA-FQ-12, TTA-FQ-23, and TTA-FQ-34) were synthesized by reacting epoxy maleic anhydride, which was prepared through the oxidization reaction of maleic anhydride by hydrogen peroxide, with phenol-formaldehyde resin containing polyamine (FQ resins series). The effects of such factors as reaction time, reaction temperature and pH value on the loading capacity of TTA in resins were investigated. The results showed that the optimum reaction conditions are as follows: time 9-12 h; temperature 90-105℃;pH value 6-10. The loading capacities of TTA can reach 0.15, 0.14, and 0.11 mmol/g-1 when the functional group of FQ resin was -OCH2CH2NHC2H4NH2, -O(CH2CH2NH)2C2H4NH2 and -O(CH2CH2NH)3C2H4NH2), respectively. The structures of resins were characterized by FTIR spectra. The primary study on the adsorption properties of the resins for metal ions showed that there are two kinds of adsorption mechanisms i.e. ion exchange and chelate in the adsorption process.TTA-FQ resins have much higher adsorption selectivity for Pb2+and Zn2+ than for Cu2+ and Ni2+. These resins can probably be used for separating Pb2+ or Zn2+ in the mixture of metal ions or for treating wastewater containing heavy metal ions.

  2. A chelating resin containing trihydroxybenzoic acid as the functional group. Synthesis and adsorption behavior for Th(IV) and U(VI) ions

    A novel glycidyl methacrylate chelating resin has been synthesized through copolymerization of glycidyl methacrylate (GMA) in the presence of divinylbenzene (DVB), the resulting resin was immobilized with 3,4,5-trihydroxybenzoic acid (THBA) to give GMA/DVB/THBA chelating resin. The adsorption of Th(IV) and U(VI) on GMA/DVB/THBA adsorbent was studied as a function of initial concentration, pH, shaking time and temperature. The novel chelating resin shows a high capacity for Th(IV) and U(VI), maximum adsorption of Th(IV) and U(VI) were 56 and 83.6 mg/g, respectively. Kinetic studies showed that the adsorption follows the pseudo second order model referring to the influence of the textural properties of the resin on the rate of adsorption. Thermodynamic parameters such as ΔH deg and ΔS deg were studied and indicated an endothermic process. (author)

  3. Correlation of acid-base properties of polymeric chelate sorbents and pH50 of gallium and indium sorption

    Complexing properties of synthesized polymeric chelate-forming sorbents - substituents of polystyrene-azo-pyrocatechol - are investigated and quantitative correlations between pKOH of functional analytical group and pH50 of chelate formation are determined to investigate regularities of interactions in element - sorbent system. Correlations obtained make it possible to realize special forecast on choice and usage of chelate sorbents for separation and concentrating of gallium and indium microquantities from objects of different nature

  4. Studies on beryllium complexes. V. Chelation of Be2+ ions by anthranilic acid

    After having determined the formation constants of anthranilic acid, the anthranilic acid-Be2+ - H2O system (0.5 M NaClO3 and t=25 deg C) has been studied. The complex BeA+ and the hydroxylated species Be2(OH)A2+, Be3(OH)3A2+, Be3(OH)3A2+ have been identified

  5. Evaluation of 111In-labeled macrocyclic chelator-amino acid derivatives for cancer imaging

    Purpose: We evaluated new 111In-labeled amino acid derivatives, in which the amino acids are conjugated with1,4,7,10-tetra-azacyclododecane-1,4,7,10-tetraacetic acid (DOTA), 1,4,7,10-tetraazacyclododecane-1,7-diacetic acid (DO2A) or 1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid (DO3A). Methods: DOTA-aminoalanine (DOTA-A), DOTA-aminohomoalanine (DOTA-H), DOTA-lysine (DOTA-L), DO2A-alanine (DO2A-A), DO3A-alanine (DO3A-A) and DO3A-homoalanine (DO3A-H) were labeled with 111In. In vitro cell uptake assays were performed usingHep3B (a human hepatoma cell line), CT26 (a mouse colon cancer cell line) and U87MG (a human glioma cell line). In vitro cell uptake inhibition assays were performed using U87MG and 111In-DO3A-H. U87MG bearing xenografted mice were subject to biodistribution, SPECT imaging, autoradiography, and immunohistochemistry studies. Results: Of the amino acid derivatives and cell lines examined, U87MG and 111In-DO3A-H showed highest uptake in vitro. This uptake was blocked by 2-aminobicyclo-[2,2,1] heptane-2-carboxylic acid (BCH) and by tryptophan. 111In-DO3A-HSPECT imaging of U87MG bearing xenografted mice visualized tumors (mean tumor-to-muscle ratio 3.16±0.74). Autoradiography and immunohistochemistry revealed that 111In-DO3A-H uptake matched L-type amino acid transporter 1 expression. Conclusion: Tumor uptake was successfully imaged using 111In-DO3A-H in U87MG bearing xenografted mice. 111In-DO3A-H appears to be useful for imaging tumors expressing L-type amino acid transporter.

  6. Preliminary chelation and dissolution effects of oxalic acid and disodium oxalate on polymeric 123-superconductors

    The polymeric 123-superconductor material was selectively etched by exposure to aqueous solutions of oxalic acid and disodium oxalate. Superconductivity decreased with time. XPS, AES, FTIR and ATF show that the amount of copper at the surface is decreased, shows the presence of bound oxalate and shows a decrease in peaks associated with superconductivity for the sample treated with oxalate

  7. Synthesis, Characterization and Chelating Properties of Benzimidazole-Salicylic Acid Combined Molecule

    Kamlesh V. Patel; Singh, Arun

    2009-01-01

    Aminomethylation (i.e. Mannich reaction) of benzimidazole was carried out by treating benzimidalzole with formaldehyde and 4-aminosalicylic acid. The resultant compound was designated as 1-(4-carboxy-3-hydroxyphenyl aminomethyl) benzimidazole (BI-SA). The transition metal complexes of Cu2+, Co2+, Ni2+, Mn2+, Zn2+ and Fe3+ of BI-SA have been prepared and characterized by elemental analyses, spectral studies, magnetic moment determination, molar conductivity measurement and microbicidal activity.

  8. Selective separation of uranium(VI) on a chelating styrene-DVB based resin containing quinaldinic acid amide group

    A new chelating styrene-DVB based resin containing quinaldinic acid amide functional group, has been synthesised and characterised. The sorption patterns of Na(I), K(I), Be(II), Ca(II), Mg(II), Zn(II), Cd(II), Cu(II), Pb(II), Ni(II), Bi(III), Fe(III), Ti(IV) and U(VI) have been studied as a function of pH. The resin sorbs U(VI) over a wide range of pH (1.0 to 4.0) with a maximum sorption of 0.32 mmol/g at pH 3.5 to 4.0. Zn(II), Cd(II), Cu(II), Na(II), Pb(II), Fe(III) and Ti(IV) are also sorbed to different extents by the resin while Na(I), K(I), Be(II), Ca(II), Mg(II) and Bi(III) are not sorbed. Conditions for separation of U(VI) from these metal ions have been identified. The eluting agent used for U(VI) is 3 N HNO3 and the recovery recorded is about 99.9 per cent (author). 12 refs., 3 tabs

  9. Environmental biogeochemistry of chelating agents and recommendations for the disposal of chelated radioactive wastes

    The environmental chemistry of the three most common aminopolycarboxylic acid chelating agents, NTA (nitrilotriacetic acid), EDTA (ethylenediaminetetraacetic acid), and DTPA (diethylenetriaminepentaacetic acid) is reviewed. This review includes information on their persistence in the environment, as well as their tendency to form complexes with actinides. Data on the sorption of chelated actinides by geologic substrates and on the uptake of chelated actinides by plants are also presented. Three different technical options for disposing chelated low-level radioactive wastes are proposed: bind the solidified chelated waste in some kind of solid matrix that has a slow leach rate and bury the waste in a ''dry'' disposal site; substitute biodegradable chelating agents in the decontamination reagent for the chelating agents that are persistent in the environment; chemically or thermally degrade the chelating agents in the waste prior to disposal. The relative advantages and disadvantages of each of these options are discussed. 81 refs

  10. Recurrent rates and risk factors associated with recurrent painful bullous keratopathy after primary phototherapeutic keratectomy

    Kasetsuwan N

    2015-09-01

    Full Text Available Ngamjit Kasetsuwan, Kanokorn Sakpisuttivanit, Usanee Reinprayoon, Vilavun Puangsricharern Department of Ophthalmology, Faculty of Medicine, Chulalongkorn University and King Chulalongkorn Memorial Hospital, Bangkok, Thailand Objective: To assess the recurrent rate, mean survival time, and risk factors associated with recurrent painful bullous keratopathy (BK after primary treatment with phototherapeutic keratectomy.Methods: Medical records from 72 patients (72 eyes who had phototherapeutic keratectomy for painful BK were evaluated. Data for sex, age, duration of BK, associated ocular and systemic diseases (hypertension, diabetes mellitus, ischemic heart disease, asthma, dyslipidemia, and rheumatoid arthritis, frequency and degree of pain (grade 1–3, visual acuity, corneal thickness, intraocular pressure, and laser setting were extracted and analyzed.Results: The mean age of the patients was 64.2±11.4 years. The mean preoperative duration of BK was 15.0±11.0 months. Most patients had pseudophakic BK (69.40%. Majority of the cases had grade 3 degree of pain (48.60%. Glaucoma and hypertension were markedly found among these patients (51.40% and 19.40%, respectively. Preoperative mean intraocular pressure and corneal thickness were 13.70±4.95 mmHg and 734.1±83.80 µm, respectively. The mean laser diameter and depth were 8.36±1.22 mm and 38.89±8.81 µm, respectively. Systemic disease was significantly associated with the risk for developing recurrent painful BK (P=0.022, hazard ratio [HR] 1.673, 95% confidence interval [CI] 1.08–2.58. The overall recurrent rate was 51%. The average duration time of recurrent painful BK was 17.3±12.9 months (range 1–50 months. The median survival time before recurrence was 29.0±6.6 months.Conclusion: Systemic disease was found to be the only risk factor significantly associated with the development of recurrent painful BK. Low recurrent rate and long mean survival time showed that phototherapeutic

  11. Estimation of Stability Constants of Copper(II) Chelates with Amino Acids by Overlapping Spheres Method

    Raos, Nenad

    2005-01-01

    The method of overlapping spheres (OS) was applied to the estimation of stability constants of mono- (log β110) and bis-complexes (log β120) of α-amino acids and their N-alkyl and N,Ndialkyl derivatives with copper(II). The central sphere, with a 0.3 or 0.4 nm radius, was placed at the central (Cu), equatorial (N) or apical (X) position of the coordination polyhedron. The overlapping volume of the central sphere and the van der Waals spheres of neighbouring atoms was calculated and correlated...

  12. Grafting iminodiacetic acid on silica nanoparticles for facilitated refolding of like-charged protein and its metal-chelate affinity purification.

    Liu, Hu; Dong, Xiaoyan; Sun, Yan

    2016-01-15

    A series of highly charged nanoscale chelators were fabricated by grafting of poly(glycidyl methacrylate-iminodiacetic acid) (pGI) chains with iminodiacetic acid (IDA) chelating group on silica nanoparticles (SNPs) via atom transfer radical polymerization (ATRP). The nanoscale chelators, denoted as SNPs-pGI, possessed a nickel ion chelating capacity as high as 2800 μmol/g, 50 times higher than the IDA-modified Sepharose FF (IDA-Sepharose) resin reported in literature and offered a high affinity binding capacity for hexahistidine-tagged enhanced green fluorescence protein (6 × His-EGFP) after nickel ion loading. More importantly, the anionic SNPs-pGI of high charge densities displayed much better performance than IDA-Sepharose in facilitating the refolding of like-charged 6 × His-EGFP from inclusion bodies (IBs). For example, for 0.2mg/mL 6 × His-EGFP IB refolding, addition of 6.2 μL/mL SNPs-pGI with the highest charge density led to a refolding yield of 90%, over 43% higher than that obtained with 460 μL/mL IDA-Sepharose. It is notable that the much higher efficiency of the nanoscale chelator was obtained with a chelator consumption corresponding to only 1.4% of IDA-Sepharose. Moreover, the highly charged SNPs-pGI could efficiently facilitate the refolding of 6 × His-EGFP at higher IB concentrations (0.4 and 0.8 mg/mL). After refolding, nickel ions addition led to the recovery of the refolded 6 × His-EGFP with high yield (80%), purity (96%) and enrichment ratio (1.8). All the results suggest that the SNPs-pGI of high charge densities were promising for cost-effective recovery of His-tagged proteins expressed as IBs with the integrative like-charge facilitated refolding and metal-chelate affinity purification strategy. PMID:26755413

  13. Lipoic acid in combination with a chelator ameliorates lead-induced peroxidative damages in rat kidney

    Sivaprasad, R.; Nagaraj, M.; Varalakshmi, P. [Department of Medical Biochemistry, University of Madras (Taramani), Chennai 600 113 (India)

    2002-08-01

    The deleterious effect of lead has been attributed to lead-induced oxidative stress with the consequence of lipid peroxidation. The present study was designed to investigate the combined effect of DL-{alpha}-lipoic acid (LA) and meso-2,3-dimercaptosuccinic acid (DMSA) on lead-induced peroxidative damages in rat kidney. The increase in peroxidated lipids in lead-poisoned rats was accompanied by alterations in antioxidant defence systems. Lead acetate (Pb, 0.2%) was administered in drinking water for 5 weeks to induce lead toxicity. LA (25 mg/kg body weight per day i.p) and DMSA (20 mg/kg body weight per day i.p) were administered individually and also in combination during the sixth week. Nephrotoxic damage was evident from decreases in the activities of {gamma}-glutamyl transferase and N-acetyl {beta}-D-glucosaminidase, which were reversed upon combined treatment with LA and DMSA. Rats subjected to lead intoxication showed a decline in the thiol capacity of the cell, accompanied by high malondialdehyde levels along with lowered activities of catalase, superoxide dismutase, glutathione peroxidase and glutathione metabolizing enzymes (glutathione reductase, glucose-6-phosphate dehydrogenase, glutathione-S-transferase). Supplementation with LA as a sole agent showed considerable changes over oxidative stress parameters. The study has highlighted the combined effect of both drugs as being more effective in reversing oxidative damage by bringing about an improvement in the reductive status of the cell. (orig.)

  14. Determination of free Gd3+ as a cyclohexanediaminetetraacetic acid complex by reversed-phase HPLC in ionic gadolinium(III) chelates

    A reversed-phase HPLC method to analyze free Gd3+ in ionic Gd chelates, Gd(EDTA)-, Gd(DPTA)2-, and Gd(DOTA)-, was developed. In the method, free Gd3+ was complexed with cyclohexanediaminetetraacetic acid (CDTA). Either the complexation was carried out before analysis or CDTA was added to the buffered mobile phase (pH 7.4, Tris-HCI) to complex the free metal in the chelate sample. The complex Gd(CDTA)- was separated from the ionic chelate by high-performance liquid chromatography on a C18 reversed-phase Nucleosil column. A fluorescence detection method with 280-and 310-nm excitation and emission wavelengths, respectively, was used for monitoring. The recoverability, the linearity, and the limit of detection (LOD) of the method were determined. The method was evaluated in terms of thermodynamic and kinetic properties of Gd(CDTA)-, Gd(EDTA)-, Gd(DTPA)2-, and Gd(DOTA)-. The LOD for Gd3+ in the ionic chelates was 39 ng. 27 refs., 4 figs., 3 tabs

  15. Transmetallation Versus β-Hydride Elimination : The Role of 1,4 Benzoquinone in Chelation-Controlled Arylation Reactions with Arylboronic Acids

    Sköld, Christian; Kleimark, Jonatan; Trejos, Alejandro; Odell, Luke R; Nilsson Lill, Sten O.; Norrby, Per-Ola; Larhed, Mats

    2012-01-01

    AbstractThe formation of an atypical, saturated, diarylated, Heck/Suzuki, domino product produced under oxidative Heck reaction conditions, employing arylboronic acids and a chelating vinyl ether, has been investigated by DFT calculations. The calculations highlight the crucial role of 1,4-benzoquinone (BQ) in the reaction. In addition to its role as an oxidant of palladium, which is necessary to complete the catalytic cycle, this electron-deficient alkene opens up a low-energy reaction pathw...

  16. Roles of manganese and organic acid chelators in regulating lignin degradation and biosynthesis of peroxidases by Phanerochaete chrysosporium.

    Perez, J.; Jeffries, T W

    1992-01-01

    We studied the effect of manganese and various organic chelators on the distribution, depolymerization, and mineralization of synthetic 14C-labeled lignins (DHP) in cultures of Phanerochaete chrysosporium. In the presence of high levels of manganese [Mn(II) or Mn(III)], along with a suitable chelator, lignin peroxidase (LiP) production was repressed and manganese peroxidase (MnP) production was stimulated. Even though partial lignin depolymerization was observed under these conditions, furthe...

  17. The Mechanism of Sol-Gel Synthesis of Normal Spinel LiMn2O4 with Chelation of Citric Acid

    WU Hui; LEI Jia-heng; CHEN Yong-xi; SUN Yu-bin; YUAN Qi-hua

    2002-01-01

    The sol-gel process of citric acid chelating with metal cations for the synthesis of normal spinel LiMn2O4 and the reaction mechanism were investigated by means of XRD, IR, TG-DTA, and SEM. The results show that at the beginning lithium citrate and chelate compound of citric acid with manganese ions formed, and then with heating the esterification and condensation reactions occured between them and glycol. The products obtained are polymers in which metal cations are distributed homogeneously on atomic scale that ensure high reactivity to cations of Li + and Mn2 + . Firing the gel prepared by this process, the lattice diffusions of solid reactant ions caused by non-homogeneity of reactants are eliminated and avoided. At 400℃ phase-pure LiMn2 O4 with nanometer scale crystallization having precise stoichiometry and perfect crystallization can be obtained. The model of chelate coordinate of double-molecule between citric acid and Mn2 + in the gel network is proposed. It is important for explaining the dispersion state of Mn2 + and the formation process of gel by this model.

  18. Fluid extraction using carbon dioxide and organophosphorus chelating agents

    Smart, Neil G.; Wai, Chien M.; Lin, Yuehe; Kwang, Yak Hwa

    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.

  19. Selective removal of Ag+ ions from nitric acid medium by alginate microcapsules, Lewatite TP 214 chelating resin, and 200 CT strongly acidic ion exchanger

    Alginate microcapsules containing bis (2, 4, 4-trimethylpenthyl) monothiophosphinic acid (Cyanex 302) were prepared for the selective removal of Ag+ ions from the reprocessing effluents of FBR-MOX fuel. The Ag+ ions are added for the adjustment of oxidation state of Plutonium. We compared uptake properties of aforementioned microcapsules with those of 200 CT a strongly acidic resin, and Lewatite TP 214, a very selective chelating resin for the Ag+ ions. Most of the uptake properties of the microcapsules were amid the 200 CT and Lewatite, and rather similar to the later. The order of uptake kinetic and breakthrough capacity were the same as: 200 CT > Microcapsules > Lewatite; and for selectivity: Lewatite > Microcapsules > 200 CT. However, high selectivity of Lewatite is rather disadvantageous because it makes the elution operation complicated. Advantages of microcapsules include simple preparation procedure, relatively high selectivity and ease of elution even with 3M nitric acid. However, their total capacity is low. For enhancing the total capacity only increasing the active component is not enough since it deteriorates the kinetics, and the new preparation techniques are necessary which are under study. (author)

  20. New method for studying the efficiency of chelating agents of the polyamine acid series for internal decontamination; Methode nouvelle d'etude de l'efficacite des chelateurs de la serie des acides polyamines pour la decontamination interne

    Lafuma, J.; Nenot, J.C.; Morin, M. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1968-07-01

    We followed the biological fate of a complex formed on one side with either a rare earth (cerium-144) or a transuranium element (plutonium-239), and on the other side with a chelating agent of the polyamino acid series (EDTA, BAETA, DTPA, TTHA). This method allowed to study: 1 - the in vivo stability of the various complexes and to compare them; 2 - the stability of the complexes as a function of the isotope - chelating agent weight relationships; 3 - the metabolism of the chelating agents resulting in stable complexes, i. e. DTPA and TTHA mainly. This simple method brought out the higher efficiency, of DTPA in chelating rare earths and plutonium and for therapeutic purposes. (authors) [French] La methode consiste a suivre le devenir biologique d'un complexe forme d'une part avec une terre rare (cerium 144) ou un transuranien (plutonium 239) et d'autre part avec un chelateur de la serie des acides polyamines (EDTA, BAETA, DTPA, TTHA). Elle permet d'etudier: 1 - la stabilite in vivo des differents complexes, de les comparer; 2 - la stabilite des complexes en fonction des rapports ponderaux isotope - chelateurs; 3 - le metabolisme des chelateurs formant des complexes stables, essentiellement DTPA et TTHA. Cette methode simple degage la suprematie du DTPA en ce qui concerne la chelation des terres rares et du plutonium, et son utilisation a des fins therapeutiques. (auteurs)

  1. Neuroprotective effect of the natural iron chelator, phytic acid in a cell culture model of Parkinson's disease

    Disrupted iron metabolism and excess iron accumulation has been reported in the brains of Parkinson's disease (PD) patients. Because excessive iron can induce oxidative stress subsequently causing degradation of nigral dopaminergic neurons in PD, we determined the protective effect of a naturally occurring iron chelator, phytic acid (IP6), on 1-methyl-4-phenylpyridinium (MPP+)-induced cell death in immortalized rat mesencephalic/dopaminergic cells. Cell death was induced with MPP+ in normal and iron-excess conditions and cytotoxicity was measured by thiazolyl blue tetrazolium bromide (MTT assay) and trypan blue staining. Apoptotic cell death was also measured with caspase-3 activity, DNA fragmentation, and Hoechst nuclear staining. Compared to MPP+ treatment, IP6 (30 μmol/L) increased cell viability by 19% (P + treatment was decreased by 55% (P < 0.01) and 52% (P < 0.05), respectively with IP6. Cell survival was increased by 18% (P < 0.05) and 42% (P < 0.001) with 30 and 100 μmol/L of IP6, respectively in iron-excess conditions. A 40% and 52% (P < 0.001) protection was observed in caspase-3 activity with 30 and 100 μmol/L IP6, respectively in iron-excess condition. Similarly, a 45% reduction (P < 0.001) in DNA fragmentation was found with 100 μmol/L IP6. In addition, Hoechst nuclear staining results confirmed the protective effect of IP6 against apoptosis. Similar protection was also observed with the differentiated cells. Collectively, our results demonstrate a significant neuroprotective effect of phytate in a cell culture model of PD

  2. The Scientific Basis for Chelation: Animal Studies and Lead Chelation

    Smith, Donald; Strupp, Barbara J.

    2013-01-01

    This presentation summarizes several of the rodent and non-human studies that we have conducted to help inform the efficacy and clinical utility of succimer (meso-2,3-dimercaptosuccincinic acid) chelation treatment. We address the following questions: (1) What is the extent of body lead, and in particular brain lead reduction with chelation, and do reductions in blood lead accurately reflect reductions in brain lead? (2) Can succimer treatment alleviate the neurobehavioral impacts of lead poi...

  3. Benzyl and Methyl Fatty Hydroxamic Acids Based on Palm Kernel Oil as Chelating Agent for Liquid-Liquid Iron(III Extraction

    Jamileh Amin

    2012-02-01

    Full Text Available Liquid-liquid iron(III extraction was investigated using benzyl fatty hydroxamic acids (BFHAs and methyl fatty hydroxamic acids (MFHAs as chelating agents through the formation of iron(III methyl fatty hydroxamate (Fe-MFHs or iron(III benzyl fatty hydroxamate (Fe-BFHs in the organic phase. The results obtained under optimized conditions, showed that the chelating agents in hexane extract iron(III at pH 1.9 were realized effectively with a high percentage of extraction (97.2% and 98.1% for MFHAs and BFHAs, respectively. The presence of a large amount of Mg(II, Ni(II, Al(III, Mn(II and Co(II ions did affect the iron(III extraction. Finally stripping studies for recovering iron(III from organic phase (Fe-MFHs or Fe-BFHs dissolved in hexane were carried out at various concentrations of HCl, HNO3 and H2SO4. The results showed that the desired acid for recovery of iron(III was 5 M HCl and quantitative recovery of iron(III was achieved from Fe(III-MFHs and Fe(III-BFHs solutions in hexane containing 5 mg/L of Fe(III.

  4. Binary and ternary chelates of Sc(III), Y(III) and La(III) with ethylenediamine tetraacetic acid as primary ligand and substituted salicylic acids as secondary ligands

    Study of ternary complex formation of several tripositive metal ions viz. Sc(III), Y(III) and La(III) with ethylenediamine tetraacetic acid (EDTA) as a primary ligand and 5-chlorosalicylic acid (CSA) or 3,5-dibromosalicylic acid (DBSA) as secondary ligands by pH-metric titration technique is reported. The stability order of metal chelates with respect to ligands is observed to be DBSA>CSA and with respect to metal ions Sc(III)>Y(III)>La(III). (B.G.W.)

  5. Extremely enhanced photovoltaic properties of dye-sensitized solar cells by sintering mesoporous TiO2 photoanodes with crystalline titania chelated by acetic acid

    Liu, Bo-Tau; Chou, Ya-Hui; Liu, Jin-Yan

    2016-04-01

    The study presents a significant improvement on the performance of dye-sensitized solar cells (DSSCs) through incorporating the crystalline titania chelated by acetic acid (TAc) into the mesoporous TiO2 photoanodes. The effects of TAc on the blocking layer, mesoporous TiO2 layer, and post-treatment have been investigated. The TAc blocking layer displays compact construction, revealing superior response time and resistance to suppress dark current compared to the blocking layer made from titanium(IV) isopropoxide (TTIP). The power conversion efficiency of DSSCs with the TAc treatment can reach as high as 10.49%, which is much higher than that of pristine DSSCs (5.67%) and that of DSSCs treated by TTIP (7.86%). We find that the TAc incorporation can lead to the decrease of charge transfer resistance and the increase of dye adsorption. The result may be attributed to the fact that the TAc possesses high crystallinity, exposed (101) planes, and acid groups chelated on surface, which are favorable for dye attachment and strong bonding at the FTO/TiO2 and the TiO2/TiO2 interfaces, These improvements result in the remarkable increase of photocurrent and thereby that of power conversion efficiency.

  6. Determination of uranium in environmental matrices by chelation ion chromatography using a high performance substrate dynamically modified with 2,6-pyridinedicarboxylic acid

    Chelation ion chromatography, involving a high efficiency neutral polystyrene-divinylbenzene resin dynamically coated with 2,6-pyridinedicarboxylic acid, has been developed as a novel technique for the quantitative determination of uranium in complex matrices. An isocratic separation method, using an eluent consisting of 1M KNO3, 0.5 M HNO3 and 0.1 mM 2,6-pyridinedicarboxylic acid, allowed the uranyl ion to elute away from matrix interferences in under ten minutes. Detection was achieved using an Arsenazo III post column reaction system. Good recoveries were obtained from spiked mineral water and sea water and the standard addition curves produced good linearity (r2 > 0.997) with a detection limit, calculated as twice baseline noise, of 20 μg L-1. The procedure was applied to the determination of trace uranium in standard reference water and sediment samples. The results obtained compared well with the certified values for uranium. (orig.)

  7. Chelated minerals for poultry

    SL Vieira

    2008-06-01

    Full Text Available Organic minerals have been subject of an increasing number of investigations recently. These compounds can be considered the most significant event regarding commercial forms of minerals targeting animal supplementation in the last decades. Minerals, especially metals, are usually supplemented in poultry feeds using cheap saline sources and have never required a lot of attention in terms of quality. On the other hand, definitions of organic minerals are very broad and frequently lead to confusion when decision-making becomes necessary. Organic minerals include any mineral bound to organic compounds, regardless of the type of existing bond between mineral and organic molecules. Proteins and carbohydrates are the most frequent candidates in organic mineral combinations. Organic fraction size and bond type are not limitations in organic mineral definition; however, essential metals (Cu, Fe, Zn, and Mn can form coordinated bonds, which are stable in intestinal lumen. Metals bound to organic ligands by coordinated bonds can dissociate within animal metabolism whereas real covalent bonds cannot. Chelated minerals are molecules that have a metal bound to an organic ligand through coordinated bonds; but many organic minerals are not chelates or are not even bound through coordinated bonds. Utilization of organic minerals is largely dependent on the ligand; therefore, amino acids and other small molecules with facilitated access to the enterocyte are supposed to be better utilized by animals. Organic minerals with ligands presenting long chains may require digestion prior to absorption. After absorption, organic minerals may present physiological effects, which improve specific metabolic responses, such as the immune response. Many studies have demonstrated the benefits of metal-amino acid chelates on animal metabolism, but the detection positive effects on live performance is less consistent.

  8. Influence of Chelating Agents on Chromium Fate in Sediment

    WANGXIAOCHANG; SUNJINHE; 等

    1996-01-01

    A laboratory investigation on reaction between chelating agents and chromium was conducted to evaluate the effect of chelating agents on the adsorption and desorption of chromium in sediment.The amount of adsorbed chromium(VI) in sediment decreased slightly by 5%-10% because of addition of chelating agents.Chelating agents inhibited the removal of Cr(Ⅲ)by sediment from solutions and the inhibiting effect was in the order:citric acid>tartaric acid>EDTA,Salicylic acid.No effect of chelating agents on desorption of chromium in sediment was observed.

  9. Phototherapeutic treatment of patients with peripheral nervous system diseases by means of LED arrays

    Zharov, Vladimir P.; Kalinin, Konstantin L.; Menyaev, Yulian A.; Zmievskoy, Gregory N.; Savin, Alexei A.; Stulin, Igor D.; Shihkerimov, Raphiz K.; Shapkina, Alla V.; Velsher, Leonid Z.; Stakhanov, Mikhail L.

    2001-05-01

    The further development of new method of phototherapy based on use of light-emitting diodes (LED) arrays has been presented. LEDs array distribution is side of cylindrical surface, covering pathology region, was used for treatment group of patients with an affected peripheral nervous system. The main group consisted of patients with humeral plexopathy - one of possible neurological manifestation of postmastectomic syndrome as result of breast cancer radical treatment. This disease was accompanied also by some other peripheral nervous system diseases: diabetic polyneuropathy, compression ischemic mononeuropathy, festering wounds and others. The phototherapeutic method is just directed on improvement of patient's conditions in combination with other traditional methods of treatment. The main parameters of photomatrix therapeutic system: wavelength - 660 nm, line width - no more than 20 nm, intensity of radiation on the surface of edema - 0.5-3 mW/cm2 (in dependence of apparatuses type). To control and study efficiency of phototreatment ultrasonic dopplerography, thermography, electromyography and viscosimetry have been used.

  10. Excimer laser phototherapeutic keratectomy : Indications, results and its role in the Indian scenario

    Rao Srinivas

    1999-01-01

    Full Text Available PURPOSE: To report indications, technique, and results of excimer phototherapeutic keratectomy (PTK, and describe possible reasons for the small numbers of such procedures performed in a referral institute in India. METHODS: Retrospective review of case records of 10 patients (11 eyes who underwent excimer PTK at our institute between February 1994 and September 1997. RESULTS: Corneal scars were the most common indication for treatment. Best-corrected visual acuity (BCVA improved in 6 eyes (mean: 2 lines of Snellen acuity. All eyes had BCVA > or = 6/12 after treatment. None of the patients experienced loss of BCVA after treatment. Unaided visual acuity improved in 3 eyes and decreased in 2 eyes. Change in spherical equivalent refraction > or = 1 diopter occurred in 77.8% of eyes after treatment. Treating central corneal scars resulted in a significant hyperopic shift in refraction. CONCLUSIONS: Excimer PTK is a safe and effective procedure for the treatment of superficial corneal opacities. Post-treatment ametropia may require further correction with optical aids. Inappropriate referrals, deep corneal scars, and cost of the procedure could have contributed to the small numbers of PTK performed at our institute. Improved understanding of procedural strengths and limitations could lead to increased use of this procedure, with satisfying results in selected patients.

  11. Excimer Laser Phototherapeutic Keratectomy for the Treatment of Clinically Presumed Fungal Keratitis

    Liang-Mao Li

    2014-01-01

    Full Text Available This retrospective study was to evaluate treatment outcomes of excimer laser phototherapeutic keratectomy (PTK for clinically presumed fungal keratitis. Forty-seven eyes of 47 consecutive patients underwent manual superficial debridement and PTK. All corneal lesions were located in the anterior stroma and were resistant to medication therapy for at least one week. Data were collected by a retrospective chart review with at least six months of follow-up data available. After PTK, infected corneal lesions were completely removed and the clinical symptoms resolved in 41 cases (87.2%. The mean ablation depth was 114.39±45.51 μm and diameter of ablation was 4.06±1.07 mm. The mean time for healing of the epithelial defect was 8.8±5.6 days. Thirty-four eyes (82.9% showed an improvement in best spectacle-corrected visual acuity of two or more lines. PTK complications included mild to moderate corneal haze, hyperopic shift, irregular astigmatism, and thinning cornea. Six eyes (12.8% still showed progressed infection, and conjunctival flap covering, amniotic membrane transplantation, or penetrating keratoplasty were given. PTK is a valuable therapeutic alternative for superficial infectious keratitis. It can effectively eradicate lesions, hasten reepithelialization, and restore and preserve useful visual function. However, the selection of surgery candidates should be conducted carefully.

  12. Tetra-n-propylporphycene as a tumour localizer: pharmacokinetic and phototherapeutic studies in mice.

    Guardiano, M; Biolo, R; Jori, G; Schaffner, K

    1989-01-01

    The porphin isomer tetra-n-propyl-porphycene (TPP) was incorporated into unilamellar liposomes of dipalmitoylphosphatidylcholine and intravenously injected at a dose of 2 mg/kg to BALB/c mice bearing a MS-2 fibrosarcoma. Pharmacokinetic studies show that TPP is selectively transported by serum lipoproteins and delivered to the tumour tissue with good efficiency (approx. 1 microgram of the TPP per g of tissue at 24 h after injection) and selectivity (ratio of TPP concentration in the tumour to the peritumoural tissue 16.7 at 24 h). Large doses of TPP are also accumulated by the liver, in agreement with the elimination of the drug via the biliary route, while no TPP is recovered from the brain. Red light-irradiation (300 J/cm2) of the tumour area caused extensive necrosis, while only little cutaneous photosensitivity was observed. Since TPP has a large absorbance in the 630-640 nm region, can be synthesized with a high degree of purity and is an efficient generator of singlet oxygen, this drug represents a potential candidate as a phototherapeutic agent for tumours. PMID:2917338

  13. Effect of low-molecular-weight carboxylic acids and selected synthetic chelates on zinc uptake and translocation in two wheat genotypes with different zinc-efficiency

    Sh. Haftbaradaran

    2013-10-01

    Full Text Available Zinc (Zn deficiency in human, which results from diets low in bioavailable zinc, could be eliminated by increasing readily plant-available Zn in soil. Root exudates and organic acids released during decomposition of soil organic matter can affect the availability of Zn. Thus, this hydroponic experiment was conducted to investigate the effect of some chelates on Zn uptake and translocation in two wheat genotypes with different zinc-efficiency. Two wheat genotypes (Triticum aestivum L. Back Cross Rowshan as zinc-efficient and Kavir as zinc-inefficient were exposed to two levels of zinc (10 and 100 µM and six different carboxylic acids (citric, tartaric, oxalic, salicylic, ethylenediamin tetraacetic acid and L-methionine. Results showed that uptake capability of free and complexed species of Zn were completely different. Zn2+ activity in nutrient solution had negative correlation with shoot dry weight and positive correlation with shoot zinc concentration in Kavir genotype, while complexed species had opposite results. Back Cross Rowshan genotype showed opposite results in comparison with Kavir genotype. The response of wheat genotypes to different organic acids varied. EDTA treatment caused the lowest shoot zinc concentration in Kavir genotype (18.8 mg/kg, while the Back Cross Rowshan genotype had highest concentration (99.5 mg/kg. Tartaric acid and citric acid caused the lowest root Zn concentration in the Kavir genotype (26.7 and 58.6 mg/kg, respectively, while the highest content was observed in the Back Cross Rowshan genotype (83.2 and 98.1 mg/kg, respectively. Catalase activity had inverse relationship with root Zn concentration in both genotypes. According to the results of this research, different responses of the wheat genotypes to organic acids are related to different mechanisms of zinc-efficiency in genotypes.

  14. Chelation in Metal Intoxication

    Flora, Swaran J.S.; Vidhu Pachauri

    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...

  15. Zinc-chelation contributes to the anti-angiogenic effect of ellagic acid on inhibiting MMP-2 activity, cell migration and tube formation.

    Sheng-Teng Huang

    Full Text Available BACKGROUND: Ellagic acid (EA, a dietary polyphenolic compound, has been demonstrated to exert anti-angiogenic effect but the detailed mechanism is not yet fully understood. The aim of this study was to investigate whether the zinc chelating activity of EA contributed to its anti-angiogenic effect. METHODS AND PRINCIPAL FINDINGS: The matrix metalloproteinases-2 (MMP-2 activity, a zinc-required reaction, was directly inhibited by EA as examined by gelatin zymography, which was reversed dose-dependently by adding zinc chloride. In addition, EA was demonstrated to inhibit the secretion of MMP-2 from human umbilical vein endothelial cells (HUVECs as analyzed by Western blot method, which was also reversed by the addition of zinc chloride. Reversion-inducing cysteine-rich protein with Kazal motifs (RECK, known to down-regulate the MMP-2 activity, was induced by EA at both the mRNA and protein levels which was correlated well with the inhibition of MMP-2 activity. Interestingly, zinc chloride could also abolish the increase of EA-induced RECK expression. The anti-angiogenic effect of EA was further confirmed to inhibit matrix-induced tube formation of endothelial cells. The migration of endothelial cells as analyzed by transwell filter assay was suppressed markedly by EA dose-dependently as well. Zinc chloride could reverse these two effects of EA also in a dose-dependent manner. Since magnesium chloride or calcium chloride could not reverse the inhibitory effect of EA, zinc was found to be involved in tube formation and migration of vascular endothelial cells. CONCLUSIONS/SIGNIFICANCE: Together these results demonstrated that the zinc chelation of EA is involved in its anti-angiogenic effects by inhibiting MMP-2 activity, tube formation and cell migration of vascular endothelial cells. The role of zinc was confirmed to be important in the process of angiogenesis.

  16. Evaluation of copper speciation in model solutions of humic acid by mini-columns packed with Chelex-100 and new chelating agents: Application to speciation of selected heavy metals in environmental water samples

    A solid-phase extraction procedure using mini-columns packed with Chelex-100 and two new chelating agents based on poly(vinyl chloride) functionalized with 3-ferrocenyl-3-hydroxydithioacrylic acid and N,N'-[1,1'-dithiobis(ethylene)]-bis(salicylideneimine) (H2sales) loaded on microcrystalline naphthalene, is reported. The columns were used to separate labile copper fractions in model solutions and in real samples with subsequent determination using electrothermal atomic absorption spectrometry (ETAAS). Various model solutions containing 20 μg L-1 of Cu2+ and 0.0, 0.2, 2.0 and 20.0 mg L-1 of humic acid, respectively, and buffered to pH 6.0, 7.0 and 8.0 were considered. Results showed a decrease in labile copper fraction with increase in humic acid concentration. Application of the procedure to speciation of Cu, Ni, Zn and Pb in various environmental water samples yielded labile fractions in the range of 1.67-55.75% against a total dissolved fraction of 44.08-69.77%. Comparison of the three chelating agents showed that H2sales had a weaker metal chelating strength than Chelex-100, but PVC-FSSH had comparable chelating strength to Chelex-100.

  17. Use of Fricke solution modified with dyes for dosimetry in phototherapeutic treatments

    Dyes and pigments (photosensitizers) are characterized by their ability to absorb visible light, and to participate in photochemical reactions. These colors are used in medicine in the dose recommended for use in photodynamic therapy (PDT). There are lasers that can meet most of the phototherapeutic agents and are capable of providing light of considerable power with precision on the injured tissue. The use of light emitting diodes (LEDs) have become feasible, thus reducing the cost of the procedures. The Dosimetry Laboratory Chemistry of the CRCN-NE/Brazilian CNEN has worked with some likely dye use in phototherapy treatments, including: methylene blue, malachite green and toluidine blue. A volume of 2.6 ml of the dosimeters was transferred to test tubes and these were irradiated with LED 24, 48, 72 and 96 acrylic simulator 110 mm x 110 mm x 80 mm at a distance of 6.5 cm from reading light source of the irradiated samples was performed on a spectrophotometer. Having obtaining excellent correlations (above 0.97) to the dosimeter calibration curves. Suggests that the dosimeter can be applied to perform a quality control in photodynamic therapy. However, further experiments should be performed before a wide application of this technique. A volume of 2.6 ml of the dosimeters was transferred to test tubes and these were irradiated with LED 24, 48, 72 and 96 acrylic simulator 110 mm x 110 mm x 80 mm at a distance of 6.5 cm from reading light source of the irradiated samples was performed on a spectrophotometer. Having obtaining excellent correlations (above 0.97) to the dosimeter calibration curves. Suggests that the dosimeter can be applied to perform a quality control in photodynamic therapy. However, further experiments should be performed before a wide application of this technique

  18. Potentiometric studies on stepwise mixed ligand chelate formation of La(III), Pr(III) or Nd(III)-N-hydroxy ethylenediamine-N,N',N'-triacetic acid-mercapto acids

    Solution equilibrium studies on the interaction between 1 : 1, Ln(III)-HEDTA binary chelate (where Ln(III) =La(III), Pr(III) or Nd(III); HEDTA = N-hydroxyl-ethyl-ethylenediamine-N,N',N'-triacetic acid) with certain mercapto acids such as thioglycollic(TGA) and thiomalic (TMEA) have been carried out potentiometrically. Formation constants of the resulting mixed ligand chelates, MAL (where M =La(III), Pr(III) or Nd(III); A = HEDTA and L = TGA or TMEA) have been determined at 30 +- 10 and μ=0.1(KNO3). The values of the formation constant Ksub(MAL) have been interpreted in terms of electrostatic repulsion indicating that the contribution due to π-interaction in M-S bond is not significant. The order of stability in terms of metals ions has been found to be La(III)< Pr(III)< Nd(III) and in terms of secondary ligand as TGA< TMEA. (auth.)

  19. Two percent ethylenediaminetetraacetic acid chelation treatment for band-shaped keratopathy, without blunt scratching after removal of the corneal epithelium

    Kobayashi W; Yokokura S; Hariya T; Nakazawa T

    2015-01-01

    Wataru Kobayashi,1 Shunji Yokokura,1 Takehiro Hariya,1 Toru Nakazawa1–3 1Department of Ophthalmology, 2Department of Retinal Disease Control, Ophthalmology, 3Department of Advanced Ophthalmic Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan Background: The purpose of this study was to assess the effectiveness of 2% ethylenediaminetetraacetic acid (EDTA) for the treatment of band-shaped keratopathy.Methods: We studied 24 eyes of 16 patients with band-shaped kerato...

  20. Regeneration of three-way automobile catalysts using biodegradable metal chelating agent-S, S-ethylenediamine disuccinic acid (S, S-EDDS)

    Regeneration of the activity of three-way catalytic converters (TWCs) was tested for the first time using a biodegradable metal chelating agent (S, S-ethylenediamine disuccinic acid (S, S-EDDS). The efficiency of this novel environmentally friendly solvent in removing various contaminants such as P, Zn, Pb, Cu and S from commercial aged three-way catalysts, and improving their catalytic performance towards CO and NO pollutants removal has been investigated. Four samples of catalysts from the front and rear inlets of two different TWCs with different mileages and aged under completely different driving conditions were investigated. The catalysts were characterized using various techniques, such as X-ray diffraction (XRD), Scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) surface area measurements (N2 adsorption at 77 K). Quantitative ICP-MS analyses and SEM-EDS studies show the removal of Zn, P and Pb. SEM-EDS images obtained at low magnification (50 μm) showed considerable differences in the surface morphology and composition after washing with S, S-EDDS. However, XRD studies indicated neither little to no removal of major contaminant compound phases nor major structural changes due to washing. Correspondingly, little or no enhancement in BET surface area was observed between the used and washed samples. Light-off curves show that the regeneration procedure employed can effectively improve the catalytic performance towards NO pollutant.

  1. Application of aminO acid chelates in infant milk formulation%氨基酸螯合物在婴幼儿配方奶粉中的应用性能研究

    张晓鸣; 张凤; 贾承胜; 夏书芹; 乐琳

    2009-01-01

    Amino acid chelates were used as mineral additives for fortification of infant milk formulation. The retention of VA, VC, VE as well as POV change during storage were evaluated when adding inorganic salts, organic salts and chelates, respectively. The results indicated that the retention of VA,VC,VE was highest in chelate group, followed by mixed organic group, and inorganic group was the lowest. Higher temperature could accelerate the degradation of vitamins mentioned above. The POV of three group of infant milk formulations all increased after storage, but it was lowest in the chelate group, which suggested that amino acid chelate was better than inorganic and other organic salts when adding into infant milk formulation.%研究氨基酸螯合物在婴幼儿配方奶粉中的应用性能.将不同微量元素添加到婴幼儿配方奶粉中研究其对体系过氧化值及VA、VC、VE稳定性的影响,发现无机组维生素降解非常迅速,螯合组最慢,混合组稍次于螯合组;温度升高会加速维生素的降解;婴幼儿配方奶粉储藏一定时间后POV均略有升高,升高幅度为无机组>混合组>螯合组,表明氨基酸螯合物在婴幼儿配方奶粉中的应用性能优于无机盐和有机盐.

  2. Scientific opinion on the safety and efficacy of iron compounds (E1 as feed additives for all species: iron chelate of amino acids, hydrate, based on a dossier submitted by Zinpro Animal Nutrition Inc.

    EFSA Panel on Additives and Products or Substances used in Animal Feed (FEEDAP

    2013-07-01

    Full Text Available The use of iron chelate of amino acids, hydrate, as source of iron is considered safe for all animal species/categories when used up to the currently authorised maximum content of total iron in complete feed, with the exception of bovines and poultry for which the maximum tolerated level is 450 mg/kg complete feed, and pets, for which the maximum tolerated level is 600 mg/kg complete feed. The FEEDAP Panel is not in the position to derive a maximum safe iron concentration in feed for horses or fish. Consumption surveys include iron-containing foodstuffs of animal origin. Since the supplementation of animal feed with iron-containing compounds has not essentially changed during the last decades, it is reasonable to assume that the iron levels in food of animal origin used in exposure scenarios originated from animals fed iron-supplemented diets. Since iron chelate of amino acids, hydrate, will be used as a substitute for other iron compounds, its use in animal nutrition would not modify consumer exposure to iron. The additive should be considered as a skin, eye and respiratory irritant and, owing to its residual peptide component, as a skin/respiratory sensitiser. Considering the high background concentration of iron in soil and water, the supplementation of feed with iron chelate of amino acids, hydrate, is not expected to pose an environmental risk. Iron chelate of amino acids, hydrate, is an effective source of iron for all animal species and categories. The FEEDAP Panel recommends that the maximum iron contents in complete feed be reduced as follows: bovines and poultry, 450 mg Fe/kg; and pets, 600 mg Fe/kg.

  3. Scientific Opinion on the safety and efficacy of copper compounds (E4) as feed additives for all species: cupric chelate of amino acids hydrate, based on a dossier submitted by Zinpro Animal Nutrition Inc.

    EFSA Panel on Additives and Products or Substances used in Animal Feed

    2013-01-01

    Cupric chelate of amino acids hydrate is safe for all animal species/categories up to the authorised maximum of total copper content in complete feed. Consumption surveys include copper from foodstuffs of animal origin. Since the supplementation of animal feed with copper-containing compounds has not essentially changed over the last decade, no change in the contribution of foodstuffs originating from supplemented animals to the overall copper intake of consumers is expected. No concerns for ...

  4. 微量元素氨基酸螯合物及其在动物生产中的应用%Amino Acid Trace Mineral Chelates in Pigs, Chicken Production

    苏从成

    2011-01-01

    Amino acid trace mineral chelates is a new organic mineral additives, known as the third generation of trace element additives. Amino acid trace mineral chelates were applied widely in animal nutrition in the recent years because of its good stability, easy digestion, high utilization, anti-bacterium and so on. This paper summarized the concept, nutritional characteristics and biological functions of amino acid trace mineral chelates and its applications in animal production.%微量元素氨基酸螯合物是一种新型有机矿物元素添加剂,被称为第三代微量元素添加剂。由于其稳定性好、生物效价高、易消化吸收、抗干扰性强等特点,迅速成为动物营养研究的热点,在各种动物生产中广泛应用。本文就微量元素氨基酸螯合物的概念、营养特性、作用机制及在动物生产中的应用进行综述。

  5. Chelation-assisted Pd-catalysed ortho-selective oxidative C-H/C-H cross-coupling of aromatic carboxylic acids with arenes and intramolecular Friedel-Crafts acylation: one-pot formation of fluorenones.

    Sun, Denan; Li, Bijin; Lan, Jingbo; Huang, Quan; You, Jingsong

    2016-03-01

    Pd-Catalysed ortho-selective oxidative C-H/C-H cross-coupling of aromatic carboxylic acids with arenes and subsequent intramolecular Friedel-Crafts acylation has been accomplished for the first time through a chelation-assisted C-H activation strategy. Starting from the readily available substrates, a variety of fluorenone derivatives are obtained in one pot. The direct use of naturally occurring carboxylic acid functionalities as directing groups avoids unnecessary steps for installation and removal of an extra directing group. PMID:26861768

  6. Quantitative measurement of metal chelation by fourier transform infrared spectroscopy

    Monika E. Miller

    2015-12-01

    Full Text Available Nutritionally important minerals are more readily absorbed by living systems when complexed with organic acids, resulting in higher consumer demand and premium prices for these products. These chelated metals are produced by reaction of metal oxides and acids in aqueous solution. However, unreacted dry blends are sometimes misrepresented as metal chelates, when in reality they are only simple mixtures of the reactants typically used to synthesize them. This practice has increased interest in developing analytical methods that are capable of measuring the extent of metal chelation for quality control and regulatory compliance. We describe a novel method to rapidly measure the percent chelation of citric and malic acids with calcium, magnesium, and zinc. Utilization of attenuated total reflectance (FTIR-ATR provides for the direct, rapid measurement of solid samples. The inclusion of an internal standard allows independent determination of either free or chelated acids from integrated areas in a single spectrum.

  7. Novel double prodrugs of the iron chelator N,N'-bis(2-hydroxybenzyl)ethylenediamine-N,N'-diacetic acid (HBED): Synthesis, characterization, and investigation of activation by chemical hydrolysis and oxidation.

    Thiele, Nikki A; Abboud, Khalil A; Sloan, Kenneth B

    2016-08-01

    The development of iron chelators suitable for the chronic treatment of diseases where iron accumulation and subsequent oxidative stress are implicated in disease pathogenesis is an active area of research. The clinical use of the strong chelator N,N'-bis(2-hydroxybenzyl)ethylenediamine-N,N'-diacetic acid (HBED) and its alkyl ester prodrugs has been hindered by poor oral bioavailability and lack of conversion to the parent chelator, respectively. Here, we present novel double prodrugs of HBED that have the carboxylate and phenolate donors of HBED masked with carboxylate esters and boronic acids/esters, respectively. These double prodrugs were successfully synthesized as free bases (7a-f) or as dimesylate salts (8a-c,e), and were characterized by (1)H, (13)C, and (11)B NMR; MP; MS; and elemental analysis. The crystal structure of 8a was solved. Three of the double prodrugs (8a-c) were selected for further investigation into their abilities to convert to HBED by stepwise hydrolysis and H2O2 oxidation. The serial hydrolysis of the pinacol and methyl esters of N,N'-bis(2-boronic acid pinacol ester benzyl)ethylenediamine-N,N'-diacetic acid methyl ester dimesylate (8a) was verified by LC-MS. The macro half-lives for the hydrolyses of 8a-c, measured by UV, ranged from 3.8 to 26.3 h at 37 °C in pH 7.5 phosphate buffer containing 50% MeOH. 9, the product of hydrolysis of 8a-c and the intermediate in the conversion pathway, showed little-to-no affinity for iron or copper in UV competition experiments. 9 underwent a serial oxidative deboronation by H2O2 in N-methylmorpholine buffer to generate HBED (k = 10.3 M(-1) min(-1)). The requirement of this second step, oxidation, before conversion to the active chelator is complete may confer site specificity when only localized iron chelation is needed. Overall, these results provide proof of principle for the activation of the double prodrugs by chemical hydrolysis and H2O2 oxidation, and merit further investigation into the

  8. Computer simulation of metal ion equilibria in biofluids. IV. Plutonium speciation in human blood plasma and chelation therapy using polyaminopolycarboxylic acids

    Duffield, J.R.; May, P.M.; Williams, D.R.

    1984-03-01

    An investigation by computer simulation into the nature of Pu(IV) binding to low-molecular ligands in human blood plasma is described. Particular consideration is given to the interactions of various chelating agents which have been or might be used for treating plutonium intoxication. Formation constants of EDTA and DTPA with Cu(II), Mg(II), Mn(II), Zn(II), and Cd(II) have been measured under biologic conditions of temperature and background electrolyte. The relative ability of these and other chelating agents to cause excretion of plutonium and the concomitant loss of certain essential trace metals has thus been assessed.

  9. Ferrocene base metal chelates

    Review of the works, devoted to different types of ferrocene metal chelates and to a possibility of ferrocene-containing ligand modification by means of complexing, is presented. Structure, properties and spectral characteristics of transitional metal, rare earth element, Cd2+, UO22+, Th4+ etc. complexes with ferrocene diketones, ferrocene acyl derivatives based on thiosemicarbazones and hydrazones and other heterometal ferrocene-containing metal chelates, are considered. 134 refs., 1 tab

  10. Chelating polymeric membranes

    Peinemann, Klaus-Viktor

    2015-01-22

    The present application offers a solution to the current problems associated with recovery and recycling of precious metals from scrap material, discard articles, and other items comprising one or more precious metals. The solution is premised on a microporous chelating polymeric membrane. Embodiments include, but are not limited to, microporous chelating polymeric membranes, device comprising the membranes, and methods of using and making the same.

  11. Monohydroxamic acids and bridging dihydroxamic acids as chelators to ruthenium(III) and as nitric oxide donors: syntheses, speciation studies and nitric oxide releasing investigations.

    Griffith, Darren; Krot, Krystyna; Comiskey, Jedd; Nolan, Kevin B; Marmion, Celine J

    2008-01-01

    The synthesis and spectroscopic characterisation of novel mononuclear Ru(III)(edta)(hydroxamato) complexes of general formula [Ru(H2edta)(monoha)] (where monoha = 3- or 4-NH2, 2-, 3- or 4-C1 and 3-Me-phenylhydroxamato), as well as the first example of a Ru(III)-N-aryl aromatic hydroxamate, [Ru(H2edta)(N-Me-bha)].H2O (N-Me-bha = N-methylbenzohydroxamato) are reported. Three dinuclear Ru(III) complexes with bridging dihydroxamato ligands of general formula [{Ru(H2edta)}2(mu-diha)] where diha = 2,6-pyridinedihydroxamato and 1,3- or 1,4-benzodihydroxamato, the first of their kind with Ru(III), are also described. The speciation of all of these systems (with the exception of the Ru-1,4-benzodihydroxamic acid and Ru-N-methylbenzohydroxamic systems) in aqueous solution was investigated. We previously proposed that nitrosyl abstraction from hydroxamic acids by Ru(III) involves initial formation of Ru(III)-hydroxamates. Yet, until now, no data on the rate of nitric oxide (NO) release from hydroxamic acids has been published. We now describe a UV-VIS spectroscopic study, where we monitored the decrease in the ligand-to-metal charge-transfer band of a series of Ru(III)-monohydroxamates with time, with a view to gaining an insight into the NO-releasing properties of hydroxamic acids. PMID:18399240

  12. Excimer laser phototherapeutic keratectomy in eyes with anterior corneal dystrophies: preoperative and postoperative ultrasound biomicroscopic examination and short-term clinical outcomes with and without an antihyperopia treatment.

    Rapuano, Christopher J.

    2003-01-01

    PURPOSE: To evaluate the use of high-frequency ultrasound biomicroscopy (UBM) in determining the depth of corneal pathology in eyes undergoing excimer laser phototherapeutic keratectomy (PTK) for primary or recurrent anterior stromal corneal dystrophies. Corneal clarity, visual acuity and refractive changes in eyes with and without an antihyperopia treatment were also analyzed. METHODS: Twenty eyes of 14 patients with anterior stromal corneal dystrophies were treated with PTK. Eyes were evalu...

  13. Scientific Opinion on the safety and efficacy of copper compounds (E4 as feed additives for all species: cupric chelate of amino acids hydrate, based on a dossier submitted by Zinpro Animal Nutrition Inc.

    EFSA Panel on Additives and Products or Substances used in Animal Feed (FEEDAP

    2013-02-01

    Full Text Available Cupric chelate of amino acids hydrate is safe for all animal species/categories up to the authorised maximum of total copper content in complete feed. Consumption surveys include copper from foodstuffs of animal origin. Since the supplementation of animal feed with copper-containing compounds has not essentially changed over the last decade, no change in the contribution of foodstuffs originating from supplemented animals to the overall copper intake of consumers is expected. No concerns for consumer safety are expected from the use of cupric chelate of amino acids hydrate in animal nutrition, which would substitute for other copper sources. The additive should be considered as a skin and eye irritant and, owing to its amino acid/peptide component, as a skin/respiratory sensitiser. Potential risks to soil organisms have been identified as a result of the application of piglet manure. Levels of copper in other types of manure are too low to create a potential risk within the timescale considered. There might also be a potential environmental concern related to the contamination of sediment resulting from drainage and the run-off of copper to surface water. In order to draw a final conclusion, further model validation is needed and some further refinement to the assessment of copper-based feed additives in livestock needs to be considered, for which additional data would be required. The use of copper-containing additives in aquaculture up to the authorised maximum of total copper content in complete feeds is not expected to pose an appreciable risk to the environment. The extent to which copper-resistant bacteria contribute to the overall antibiotic resistance situation cannot be quantified at present. Cupric chelate of amino acids hydrate is recognised as an efficacious source of copper to meet animal requirements.

  14. Scientific opinion on the safety and efficacy of iron compounds (E1) as feed additives for all species: iron chelate of amino acids, hydrate, based on a dossier submitted by Zinpro Animal Nutrition Inc.

    EFSA Panel on Additives and Products or Substances used in Animal Feed (FEEDAP)

    2013-01-01

    The use of iron chelate of amino acids, hydrate, as source of iron is considered safe for all animal species/categories when used up to the currently authorised maximum content of total iron in complete feed, with the exception of bovines and poultry for which the maximum tolerated level is 450 mg/kg complete feed, and pets, for which the maximum tolerated level is 600 mg/kg complete feed. The FEEDAP Panel is not in the position to derive a maximum safe iron concentration in feed for horses o...

  15. Tin-117m-labeled stannic (Sn/sup 4 +/) chelate of diethylenetriamine pentaacetic acid (DTPA) for application in diagnosis and therapy

    Srivastava, S.C.; Meinken, G.E.; Richards, P.

    1983-08-25

    The radiopharmaceutical reagents of this invention and the class of Tin-117m radiopharmaceuticals are therapeutic and diagnostic agents that incorporate gamma-emitting nuclides that localize in bone after intravenous injection in mammals (mice, rats, dogs, and rabbits). Images reflecting bone structure or function can then be obtained by a scintillation camera that detects the distribution of ionizing radiation emitted by the radioactive agent. Tin-117m-labeled chelates of stannic tin localize almost exclusively in cortical bone. Upon intravenous injection of the reagent, the preferred chelates are phosphonate compounds, preferable, PYP, MDP, EHDP, and DTPA. This class of reagents is therapeutically and diagnostically useful in skeletal scintigraphy and for the radiotherapy of bone tumors and other disorders.

  16. The experimental study on protective effects and mechanisms of chelating agents of catechols amino carboxylic acid for radiation injury induced by actimides(Th-234)

    The decorporative efficacy and antioxidative action of prompt and delayed consecutive administration of catecholicpolyaminopolycarboxylate ligands, 7601 and 9501 for radiothorium in mice were investigated. DTPA and Vitamin E were used as positive controls. The competitive abilities of 7601 and 9501 to mobilize the thorium with BSA were studied. Their inhibition effects on superoxide anionas radicals were measured with electron spin resonance. The results showed that 7601 and 9501 are able to effectively prevent the internal radiation injury induced radiothorium, attributing to their double functions of pronounced removal effectiveness and antioxidative action. Their protective effects were better than DTPA and Vitamin E. The mechanisms of protective effects of 7601 and 9501 for internal radiation injury was close related to competitive ability of chelating agent to chelate the thorium with BSA and oxygen free radical scavenging activities

  17. Comments on chelation therapy

    The primary purpose of actinide chelation is to decrease the risk from radiation-induced cancer. While occupational exposures in the past have mainly involved low specific activity 239Pu, future exposures will increasingly involve high specific activity plutonium, americium, and curium - all of which clear more rapidly from the lung. This will tend to shift the cancer risk from lung to bone and liver. Although therapy with Ca- or Zn-DTPA rapidly removes 241Am from the canine, the sub-human primate, and the human liver, improved methods for removal from bone and lung are needed. DTPA can remove 241Am more easily from the growing skeleton of a child than from the mature skeleton of an adult. Investigators at Karlsruhe are developing chelation agents for oral administration and are investigating the reduction in local dose to bone resulting from chelation therapy

  18. Lanthanon chelates of monoprotic tridentate schiff base

    3-(N-thiophene-2-aldimino)propanoic acid (HTP), and its lanthanon chelates were synthesised and studied by physico-chemical techniques. Irving-Rossotti method was followed to determine the dissociation constants of the ligand and formation constants of its lanthanon chelates in aqueous medium (ionic strength μ = 0.01, 0.05 and 0.1 M NaClO4) at 25 0C, 35 0C and 45 0C. Solid lanthanon chelates were characterised by molecular mass, elemental analyses, conductance, magnetic, thermal and spectral analyses and were assigned 1 : 3 (metal-ligand) stoichiometry in which the lanthanon shows nine coordination numbers. Covalent nature of metal-ligand bond was found to increase with increase in atomic number of central lanthanide ion. (author)

  19. Optimisation and status of chelation therapy

    The calcium trisodium salt of diethylenetriaminepentaacetic acid (Ca-DTPA) remains the chelating agent of choice for treatment of incorporated actinides. The zinc trisodium salt (Zn-DTPA) represents a less toxic alternative, when Ca-DTPA is contra-indicated as well as for prolonged chelation therapy; in acute incorporation cases it would be less effective than Ca-DTPA. Specific ion binding chelators such as desferrioxamine (DFOA) and linear tetracatechoylamides, e.g., LICAM(C) proved more effective in animals injected with Pu, Th and Np (not with Am!) but only concerning the radioactivity in the bone; that in the kidneys was substantially increased. The combinations of DFOA or LICAM(C) with Ca-DTPA exerted the best overall effects. After incorporation of soluble uranium-compounds, an infusion of sodium bicarbonate seems at present the most reasonable for enhancing the uranium-excretion and prevention of kidney damage. (author)

  20. Clinical results of a new high-phototherapeutic-efficiency blue-green lamp for the management of hyperbilirubinemia

    Donzelli, Gian Paolo; Pratesi, Simone; Agati, Giovanni; Fusi, Franco; Pratesi, Riccardo

    1996-01-01

    We report a preliminary study on the introduction of a new, blue-green fluorescent lamp with high phototherapeutic efficiency in the treatment of neonatal hyperbilirubinemia. The lamp (New Lamp) has an emission spectrum, peaked at 490 nm and about 40 nm wide, that was not previously investigated in clinical trials. Our study demonstrates the significantly greater efficacy of the New Lamp in decreasing the bilirubin serum level, in comparison with the most commonly used blue fluorescent lamp. The rate of decline of bilirubin concentration with the New Lamp was twice that with Philips/BB light. The success of the blue-green PT is mainly due to the combined effects of the (1) increase from blue to green of the quantum yield for lumirubin, that is the bilirubin photoproduct rapidly excreted from the organism; (2) corresponding decrease of the configurational photoisomer, formed with high concentration but not excreted from the organism; (3) filtering effect of the skin, which attenuates more blue than green light. Our results represent the first significant improvement of phototherapy efficiency following the development and introduction of the special-blue lamp by Sisson in 1970. The phototherapy exposure time has now been reduced to less than 1-day in preterm infants, ensuring less stress to the infant and less interference with nursing care.

  1. Mixed-chelate therapy of intratracheally deposited cadmium oxide

    Mixed-chelate treatment with EDTA and salicylic acid was no more effective in accelerating the removal of intratracheally instilled 109CdO, or in protecting against CdO-induced mortality, than was EDTA given alone

  2. Chelation Therapy for Mercury Poisoning

    Rong Guan; Han Dai

    2009-01-01

    Chelation therapy has been the major treatment for heavy metal poisoning. Various chelating agents have been developed and tested for treatment of heavy metal intoxications, including mercury poisoning. It has been clearly shown that chelating agents could rescue the toxicity caused by heavy metal intoxication, but the potential preventive role of chelating agents against heavy metal poisoning has not been explored much. Recent paper by Siddiqi and colleagues has suggested a protective role o...

  3. Adsorptive separation of rare earths by using chelating chitosan

    Two kinds of chelating chitosan were prepared by chemically modifying chitosan with functional groups of EDTA or DTPA, abbreviated as EDTA- and DTPA-chitosan hereafter, respectively, to investigate the adsorption behaviour for rare earths the mutual separation of which is the most difficult among metal ions on these chelating chitosan from dilute hydrochloric or sulfuric acid solution. The plots of the distribution ratio of a series of rare earths against equilibrium pH lay on different straight lines with slope of 3 corresponding to each earth for both of two chelating chitosan, suggesting that 3 hydrogen ions are released for the adsorption of unit ion of each rare earth by chelate formation with the functional group of EDTA or DTPA and that mutual adsorptive separation between adjacent rare earth is possible with these chelating chitosan. Apparent equilibrium constants of the adsorption were evaluated from the intercepts of these straight lines with the ordinate for each rare earth and for both chelating chitosan. It was found that the equilibrium constants of adsorption on EDTA- or DTPA-chitosan are quite analogous to those of chelate formation with EDTA or DTPA themselves, suggesting that chelating characteristics of these complexones is still maintained after their immobilization on polymer matrices of chitosan. (author)

  4. Fixation kinetics of chelated and non-chelated zinc in semi-arid alkaline soils: application to zinc management

    Udeigwe, Theophilus K.; Eichmann, Madeleine; Menkiti, Matthew C.

    2016-07-01

    This study was designed to examine the fixation pattern and kinetics of zinc (Zn) in chelated (ethylenediaminetetraacetic acid, EDTA) and non-chelated mixed micronutrient systems of semi-arid alkaline soils from the Southern High Plains, USA. Soils were characterized for a suite of chemical and physical properties and data obtained from extraction experiments fitted to various kinetic models. About 30 % more plant-available Zn was fixed in the non-chelated system within the first 14 days with only about 18 % difference observed between the two systems by day 90, suggesting that the effectiveness of the chelated compounds tended to decrease over time. The strengths of the relationships of change in available Zn with respect to other micronutrients (copper, iron, and manganese) were higher and more significant in the non-chelated system (average R2 of 0.83), compared to the chelated (average R2 of 0.42). Fixation of plant-available Zn was best described by the power-function model (R2 = 0.94, SE = 0.076) in the non-chelated system, and was poorly described by all the models examined in the chelated system. Reaction rate constants and relationships generated from this study can serve as important tools for micronutrient management and for future micronutrient modeling studies on these soils and other semi-arid regions of the world.

  5. EDTA: the chelating agent under environmental scrutiny

    Claudia Oviedo; Jaime Rodríguez

    2003-01-01

    The chelating agent EDTA (ethylenediaminetetraacetic acid) is a compound of massive use world wide with household and industrial applications, being one of the anthropogenic compounds with highest concentrations in inland European waters. In this review, the applications of EDTA and its behavior once it has been released into the environment are described. At a laboratory scale, degradation of EDTA has been achieved; however, in natural environments studies detect poor biodegradability. It is...

  6. Examining the fixation kinetics of chelated and non-chelated copper micronutrient and the applications to micronutrient management in semi-arid alkaline soils

    T. K. Udeigwe; M. B. Eichmann; Menkiti, M. C.

    2015-01-01

    The relationship between the deficiency of a nutrient in plants and its total concentration in the soil is complex. This study examined and compared the fixation and fixation kinetics of copper (Cu) in chelated (Ethylene diamine tetraacetic acid, EDTA) and non-chelated mixed systems of micronutrients in the semi-arid soils of the Southern High Plains, US using findings from Cu extraction studies and kinetic models. Approximately, 22 % more Cu was fixed in the non-chelated system with...

  7. Extraction of metals using supercritical fluid and chelate forming ligand

    A method of extracting metalloid and metal species from a solid or liquid material by exposing the material to a supercritical fluid solvent containing a chelating agent is described. The chelating agent forms chelates that are soluble in the supercritical fluid to allow removal of the species from the material. In preferred embodiments, the extraction solvent is supercritical carbon dioxide and the chelating agent is a fluorinated β-diketone. In especially preferred embodiments the extraction solvent is supercritical carbon dioxide, and the chelating agent comprises a fluorinated β-diketone and a trialkyl phosphate, or a fluorinated β-diketone and a trialkylphosphine oxide. Although a trialkyl phosphate can extract lanthanides and actinides from acidic solutions, a binary mixture comprising a fluorinated β-diketone and a trialkyl phosphate or a trialkylphosphine oxide tends to enhance the extraction efficiencies for actinides and lanthanides. The method provides an environmentally benign process for removing contaminants from industrial waste without using acids or biologically harmful solvents. The method is particularly useful for extracting actinides and lanthanides from acidic solutions. The chelate and supercritical fluid can be regenerated, and the contaminant species recovered, to provide an economic, efficient process. 7 figs

  8. Chelation therapy for metal intoxication: comments from a thermodynamic viewpoint.

    Nurchi, Valeria Marina; Alonso, Miriam Crespo; Toso, Leonardo; Lachowicz, Joanna Izabela; Crisponi, Guido

    2013-10-01

    Chelation therapy plays a prominent role in the clinical treatment of metal intoxication. In this paper the principal causes of metal toxicity are exposed, and the chemical and biomedical requisites of a chelating agent are sketched. The chelating agents currently in use for scavenging toxic metal ions from humans belong to few categories: those characterized by coordinating mercapto groups, by oxygen groups, poliaminocarboxylic acids, and dithiocarbamates. Considering that the complex formation equilibria have been studied for less than 50% of chelators in use, some reflections on the utility of stability constants are presented, together with an evaluation of ligands under the stability profile. The competition between endogenous and toxic target metal ions for the same chelating agent is furthermore examined. A thorough examination of stability constant databases has allowed to select, for each toxic metal, the ligands distinguished by the best pMe values. Even though this selection does not consider the biomedical requisites of a chelating agent, it gives a clear picture both of the pMe values that can be attained, and of the most appropriate chelators for each metal ion. PMID:23895193

  9. Iron chelating active packaging: Influence of competing ions and pH value on effectiveness of soluble and immobilized hydroxamate chelators.

    Ogiwara, Yoshiko; Roman, Maxine J; Decker, Eric A; Goddard, Julie M

    2016-04-01

    Many packaged foods utilize synthetic chelators (e.g. ethylenediaminetetraacetic acid, EDTA) to inhibit iron-promoted oxidation or microbial growth which would result in quality loss. To address consumer demands for all natural products, we have previously developed a non-migratory iron chelating active packaging material by covalent immobilization of polyhydroxamate and demonstrated its efficacy in delaying lipid oxidation. Herein, we demonstrate the ability of this hydroxamate-functionalized iron chelating active packaging to retain iron chelating capacity; even in the presence of competing ions common in food. Both immobilized and soluble hydroxamate chelators retained iron chelating capacity in the presence of calcium, magnesium, and sodium competing ions, although at pH 5.0 the presence of calcium reduced immobilized hydroxamate iron chelation. A strong correlation was found between colorimetric and mass spectral analysis of iron chelation by the chelating packaging material. Such chelating active packaging may support reducing additive use in product formulations, while retaining quality and shelf life. PMID:26593563

  10. Contribution to the study of beryllium complexes. IX. Chelation of Be2+ ions by 3-hydroxy butanoic and 2-hydroxy 2-methyl propanoic acids, potentiometric study

    In the field of work on complexation of beryllium, complex equilibria in aqueous solution between beryllium (II) and 3-hydroxybutanoic acid (HA) and 2-hydroxy-2-methyl propanoic acid (HA) were studied by potentiometric (alkalimetric) titration (at ionic strength = 0.5 M by NaClO4 and a temperature T = 25.0 +- 0.10C to show the influence of hydroxyl group in carboxylic ligands. For the system 3-hydroxy butanoic acid, the results show the presence of two mononuclear species: BeA+ and BeA2 and one hydrolized complex: Be3(OH)3A2, but for 2-hydroxy-2-methylpropanoic acid an additional species is identified, in what the alcoolic function is dissociated: Be(H-1A). The formation constants are reported

  11. Inositol hexa-phosphate: a potential chelating agent for uranium

    Cebrian, D.; Tapia, A.; Real, A.; Morcillo, M.A. [Radiobiology Laboratory, Radiation Dosimetry Unit, Department of Environment, CIEMAT, Avda Complutense 22, 28040 Madrid (Spain)

    2007-07-01

    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 hexa-phosphate (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 hexa-phosphate for uranium, suggesting that it could be an effective chelating agent for uranium in vivo. (authors)

  12. Inositol hexa-phosphate: a potential chelating agent for uranium

    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 hexa-phosphate (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 hexa-phosphate for uranium, suggesting that it could be an effective chelating agent for uranium in vivo. (authors)

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

    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.

  14. SORPTION OF Cu(II) BY POLY(HYDROXAMIC ACID) CHELATING EXCHANGER PREPARED FROM POL(YMETHYL ACRYLATE) GRAFTED OIL PALM EMPTY FRUIT BUNCH (OPEFB)

    Md Jelas Haron; Mariati Tiansih; Nor Azowa Ibrahim; Anuar Kassim; W. M. Z. Wan Yunus

    2009-01-01

    This paper describes the preparation of chemically modified oil palm empty fruit bunch (OPEFB) with hydroxamic acid functional group and its use for the sorption of Cu(II) from aqueous solution. OPEFB was grafted with poly(methylacrylate) (PMA), using H2O2/Fe2+ as initiator. The PMA grafted OPEFB (PMA-OPEFB) was treated with hydroxylammonium chloride in alkaline medium to produce hydroxamic acid grafted fiber (PHA-OPEFB). The FTIR spectrum of OPEFB grafted with PMA showed an intense absorpt...

  15. Some aspects of chelation chemistry

    The notions used in chelation chemistry are defined and the possibilities of the experimental recognition of complex formation are described. A review of the quantitative aspects of chelation is given, especially under biological conditions. Some rules concerning the general behaviour of the various metal ions and the organic ligands in chelation phenomena are presented and the specificity problem is discussed. The present status of the decontamination of the main fission products, e.g. rare-earth metals and strontium, with the aid of complexing agents is analysed from a chemical point of view. (author)

  16. The Increased Promotion in Cobalt-Molybdenum Hydrodesulfurization Catalysts Supported on Alumina, Activated Carbon and Zirkonia by the Chelating Agent Nitrilotriacetic Acid

    Kaluža, Luděk

    2013-01-01

    The most active CoMo/Al2O3, C and ZrO2 catalysts in benzothiophene HDS were prepared by the impregnation of the support from the solution made by dissolution of MoO3, CoCO3 and nitrilotriacetic acid in water followed by sulfidation without previous calcination.

  17. Metal based pharmacologically active agents: Synthesis, structural characterization, molecular modeling, CT-DNA binding studies and in vitro antimicrobial screening of iron(II) bromosalicylidene amino acid chelates

    Abdel-Rahman, Laila H.; El-Khatib, Rafat M.; Nassr, Lobna A. E.; Abu-Dief, Ahmed M.; Ismael, Mohamed; Seleem, Amin Abdou

    2014-01-01

    In recent years, great interest has been focused on Fe(II) Schiff base amino acid complexes as cytotoxic and antitumor drugs. Thus a series of new iron(II) complexes based on Schiff bases amino acids ligands have been designed and synthesized from condensation of 5-bromosalicylaldehyde (bs) and α-amino acids (L-alanine (ala), L-phenylalanine (phala), L-aspartic acid (aspa), L-histidine (his) and L-arginine (arg)). The structure of the investigated iron(II) complexes was elucidated using elemental analyses, infrared, ultraviolet-visible, thermogravimetric analysis, as well as conductivity and magnetic susceptibility measurements. Moreover, the stoichiometry and the stability constants of the prepared complexes have been determined spectrophotometrically. The results suggest that 5-bromosalicylaldehyde amino acid Schiff bases (bs:aa) behave as dibasic tridentate ONO ligands and coordinate to Fe(II) in octahedral geometry according to the general formula [Fe(bs:aa)2]ṡnH2O. The conductivity values between 37 and 64 ohm-1 mol-1 cm2 in ethanol imply the presence of nonelectrolyte species. The structure of the complexes was validated using quantum mechanics calculations based on accurate DFT methods. Geometry optimization of the Fe-Schiff base amino acid complexes showed that all complexes had octahedral coordination. In addition, the interaction of these complexes with (CT-DNA) was investigated at pH = 7.2, by using UV-vis absorption, viscosity and agarose gel electrophoresis measurements. Results indicated that the investigated complexes strongly bind to calf thymus DNA via intercalative mode and showed a different DNA binding according to the sequence: bsari > bshi > bsali > bsasi > bsphali. Moreover, the prepared compounds are screened for their in vitro antibacterial and antifungal activity against three types of bacteria, Escherichia coli, Pseudomonas aeruginosa and Bacillus cereus and three types of anti fungal cultures, Penicillium purpurogenium, Aspergillus

  18. Chelation therapy in intoxications with mercury, lead and copper

    Cao, yang; Skaug, Marit Aralt; Andersen, Ole;

    2015-01-01

    In the present review we provide an update of the appropriate use of chelating agents in the treatment of intoxications with compounds of mercury, lead and copper. The relatively new chelators meso-2,3-dimercaptosuccinic acid (DMSA) and 2,3-dimercapto-propanesulphonate (DMPS) can effectively...... mobilize deposits of mercury as well as of lead into the urine. These drugs can be administered orally and have relatively low toxicity compared to the classical antidote dimercaptopropanol (BAL). d-Penicillamine has been widely used in copper overload, although 2,3-dimercaptosuccinic acid or...

  19. Synthesis, structure elucidation, biological screening, molecular modeling and DNA binding of some Cu(II) chelates incorporating imines derived from amino acids

    Abdel-Rahman, Laila H.; Abu-Dief, Ahmed M.; Ismael, Mohammed; Mohamed, Mounir A. A.; Hashem, Nahla Ali

    2016-01-01

    Three tridentate Schiff bases amino acids were prepared by direct condensation of 3-methoxysalicylaldehyde (MS) or 4-diethylaminosalicylaldehyde (DS) with α-amino acid ligands [L-phenylalanine (P), L-histidine (H) and DL-tryptophan (T)]. The prepared Schiff bases amino acids were investigated by melting points, elemental analysis, 1HNMR and 13CNMR, IR, UV-Vis spectra, conductivity and magnetic measurements analyses. Subsequently, copper was introduced and Cu(II) complexes formed. These complexes were analyzed by thermal and elemental analyses and further investigated by FT-IR and UV/Vis spectroscopies. The experimental results indicating that all Cu(II) complexes contain hydrated water molecules (except DSPCu complex) and don't contain coordinated water molecules. The kinetic and thermal parameters were extracted from the thermal data using Coast and Redfern method. The molar conductance values of the Schiff base amino acid ligands and their Cu(II) complexes were relatively low, showing that these compounds have non-electrolytic nature. Magnetic susceptibility measurements showed the diamagnetic nature of the Schiff base amino acid ligands and paramagnetic nature of their complexes. Additionally, a spectrophotometric method was determined to extract their stability constants. It was found that the complexes possess 1:2 (M:L) stoichiometry. The results suggested that 3-methoxysalicylaldehyde and 4-diethylaminosalicylaldehyde amino acid Schiff bases behave as monobasic tridentate ONO ligands and coordinate Cu(II) ions in octahedral geometry according to the general formula [Cu(HL)2]·nH2O. To further understanding the structural and electronic properties of these complexes, Density Functional Theory (DFT) calculations were employed and provided a satisfactory description. The optimized structures of MST Schiff base ligand and its complex were calculated using DFT. The antimicrobial activity of the Schiff base ligands and their complexes were screened against some

  20. Iron chelators ICL670 and 311 inhibit HIV-1 transcription

    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 suggesting that inhibition of CDK2 by iron chelators might also affect HIV-1 transcription. Here we evaluated the effect of a clinically approved orally effective iron chelator, 4-[3,5-bis-(hydroxyphenyl)-1,2,4-triazol-1-yl]-benzoic acid (ICL670) and 311 on HIV-1 transcription. Both ICL670 and 311 inhibited Tat-induced HIV-1 transcription in CEM-T cells, 293T and HeLa cells. Neither ICL670 nor 311 induced cytotoxicity at concentrations that inhibited HIV-1 transcription. The chelators decreased cellular activity of CDK2 and reduced HIV-1 Tat phosphorylation by CDK2. Neither ICL670A or 311 decreased CDK9 protein level but significantly reduced association of CDK9 with cyclin T1 and reduced phosphorylation of Ser-2 residues of RNA polymerase II C-terminal domain. In conclusion, our findings add to the evidence that iron chelators can inhibit HIV-1 transcription by deregulating CDK2 and CDK9. Further consideration should be given to the development of iron chelators for future anti-retroviral therapeutics

  1. Overview of current chelation practices

    Aydinok, Y.

    2011-01-01

    Deferoxamine (DFO) is reference standard therapy for transfusional iron overload since the 1980s. Although it is a highly effective iron chelator, the compliance problem to subcutaneous administration of DFO remains as the major problem. The oral chelator Deferiprone (DFP) has no marketing licence in North America, however, it has been licensed in India since 1994 and the European Union (EU) granted marketing approval for DFP in 1999, specifically for patients with thalassemia major when DFO ...

  2. Bifunctional Chelates for Metal Nuclides

    Brechbiel, Martin W.

    2007-01-01

    The use of “non-standard” metallic radionuclides continues to be an expanding field of investigation. Radiolabeling small molecules, peptides, proteins, and up to nano-particles are all areas of active investigation for both diagnostic and therapeutic applications. All require a common variable – the need for appropriate chelation chemistry for adequate sequestration of the metallic radionuclide that is equal to the intended application. A brief overview of the array of the chelation chemistr...

  3. Alarming use of chelation therapy

    Crisponi, Guido; Nurchi, Valeria Marina; Lachowicz, Joanna I.; Crespo-Alonso, Miriam; Zoroddu, Maria Antonietta; Peana, Massimiliano Francesco

    2014-01-01

    Chelation therapy is a consolidated medical procedure used primarily to hinder the effects of toxic metal ions on human tissues. Its application spans a broad spectrum of disorders, ranging from acute metal intoxication to genetic metal-overload. The use of chelating agents is compromised by a number of serious side effects, mainly attributable to perturbed equilibrium of essential metal ion homeostasis and dislocation of complexed metal ions to dangerous body sites. For this reason, chelatio...

  4. Oxidation of calprotectin by hypochlorous acid prevents chelation of essential metal ions and allows bacterial growth: Relevance to infections in cystic fibrosis.

    Magon, Nicholas J; Turner, Rufus; Gearry, Richard B; Hampton, Mark B; Sly, Peter D; Kettle, Anthony J

    2015-09-01

    Calprotectin provides nutritional immunity by sequestering manganese and zinc ions. It is abundant in the lungs of patients with cystic fibrosis but fails to prevent their recurrent infections. Calprotectin is a major protein of neutrophils and composed of two monomers, S100A8 and S100A9. We show that the ability of calprotectin to limit growth of Staphylococcus aureus and Pseudomonas aeruginosa is exquisitely sensitive to oxidation by hypochlorous acid. The N-terminal cysteine residue on S100A9 was highly susceptible to oxidation which resulted in cross-linking of the protein monomers. The N-terminal methionine of S100A8 was also readily oxidized by hypochlorous acid, forming both the methionine sulfoxide and the unique product dehydromethionine. Isolated human neutrophils formed these modifications on calprotectin when their myeloperoxidase generated hypochlorous acid. Up to 90% of the N-terminal amine on S100A8 in bronchoalveolar lavage fluid from young children with cystic fibrosis was oxidized. Oxidized calprotectin was higher in children with cystic fibrosis compared to disease controls, and further elevated in those patients with infections. Our data suggest that oxidative stress associated with inflammation in cystic fibrosis will stop metal sequestration by calprotectin. Consequently, strategies aimed at blocking extracellular myeloperoxidase activity should enable calprotectin to provide nutritional immunity within the airways. PMID:26006104

  5. SORPTION OF Cu(II BY POLY(HYDROXAMIC ACID CHELATING EXCHANGER PREPARED FROM POL(YMETHYL ACRYLATE GRAFTED OIL PALM EMPTY FRUIT BUNCH (OPEFB

    Md Jelas Haron

    2009-11-01

    Full Text Available This paper describes the preparation of chemically modified oil palm empty fruit bunch (OPEFB with hydroxamic acid functional group and its use for the sorption of Cu(II from aqueous solution. OPEFB was grafted with poly(methylacrylate (PMA, using H2O2/Fe2+ as initiator. The PMA grafted OPEFB (PMA-OPEFB was treated with hydroxylammonium chloride in alkaline medium to produce hydroxamic acid grafted fiber (PHA-OPEFB. The FTIR spectrum of OPEFB grafted with PMA showed an intense absorption band at 1734 cm-1 which is attributed to C=O vibration in the grafted ester. After hydroxylamine treatment, the intensity of absorption band at 1734 cm-1 decreased and new bands appeared at the 1640 cm-1 related to C=O vibration in hydroxamic acid and at the 1568 cm-1 related to the N-H amide. Sorption of Cu(II by PHA-OPEFB was effective over a pH range of 4 to 6. The sorption followed the Langmuir model with maximum capacities of 74.1 mg g-1 at 25 °C. The sorption process was exothermic, as shown by the negative value of enthalpy change, H. The free energy change (G for the sorption was negative, showing that the sorption process was spontaneous. A kinetic study showed that the Cu(II sorption followed a second order kinetic model.

  6. Flame Atomic Absorption Spectrometric Determination of Trace Metal Ions in Environmental and Biological Samples After Preconcentration on a Newly Developed Amberlite XAD-16 Chelating Resin Containing p-Aminobenzene Sulfonic Acid.

    Islam, Aminul; Ahmad, Akil; Laskar, Mohammad Asaduddin

    2015-01-01

    Amberlite® XAD-16 was functionalized with p-aminobenzene sulfonic acid via an azo spacer in order to prepare a new chelating resin, which was then characterized by water regain value, hydrogen ion capacity, elemental analyses, and IR spectral and thermal studies. The maximum uptake of Cu(II), Ni(II), Zn(II), Co(II), Cr(III), Fe(III), and Pb(II) ions was observed in the pH range 4.0-6.0 with the corresponding half-loading times of 6.5, 7.0, 8.0, 9.0, 11.0, 8.5, and 16.5 min. The sorption data followed Langmuir isotherms and a pseudo-second-order model. Thermodynamic quantities, ΔH and ΔS, based on the variation of the distribution coefficient with temperature were also evaluated. High preconcentration factors of 60-100 up to a low preconcentration limit of 4.0-6.6 μg/L have been achieved for the metal ions. The validity of the method was checked by analyzing standard reference materials and recoveries of trace metals after spiking. The analytical applications of the method were explored by analyzing natural water, mango pulp, mint leaves, and fish. PMID:25857893

  7. Chelating impact assessment of biological ad chemical chelates on metal extraction from contaminated soils

    Soil contamination is the result of uncontrolled waste dumping and poor practices by humans. Of all the pollutants heavy metals are of particular concern due to their atmospheric deposition, leaching capacity and non-biodegradability. Heavy metal containing effluent is discharged into the agricultural fields and water bodies. This results in the accumulation of heavy metals in soil and the crops grown on that soil. Studies have revealed detrimental impacts on soil fertility and the poor health of animals and humans. Phytoextraction is widely researched for remediation of heavy metal contaminated soil. To enhance the effect of phytoextraction heavy metals have to be available to the plants in soluble form. In this study the potential of different chelating agents was assessed in solubilizing the heavy metals making easy for plants to uptake them. For this purpose efficient chemical and biological chelating agent had to be identified. Along with that an optimum dose and application time for chemical chelating agent was determined. Ethylenediamine tetraacetic acid (EDTA), Diethylene triamine pentaacetic acid (DTPA), Nitriloacetic acid (NTA) were applied to the soil, containing Pb, Cr, Cu and Cd, at different concentrations and application time. Aspergillus niger and Aspergillus flavus were incubated in soil for different time periods. In correspondence with findings of the study, Pb and Cr were best solubilized by 5mM EDTA. For Cd and Cu 5mM DTPA carried out efficient chelation. NTA showed relatively inadequate solubilisation, although for Cr it performed equal to EDTA. A. niger and A. flavus instead of solubilizing adsorbed the metals in their biomass. Adsorption was mainly carried out by A. niger. (author)

  8. Examining the fixation kinetics of chelated and non-chelated copper and the applications to micronutrient management in semiarid alkaline soils

    Udeigwe, T. K.; Eichmann, M. B.; Menkiti, M. C.; Kusi, N. Y. O.

    2016-02-01

    This study examined and compared the fixation and fixation kinetics of copper (Cu) in chelated (ethylene diamine tetraacetic acid, EDTA) and non-chelated mixed systems of micronutrients in the semiarid soils of the Southern High Plains, USA, using findings from Cu extraction studies and kinetic models. Approximately, 22 % more Cu was fixed in the non-chelated system compared to the chelated within the first 14 days with only 7 % difference between the two systems by day 90. Findings suggest a decrease in the effectiveness of chelated micronutrients over time, highlighting the significance of timing even when chelated micronutrients are used. The strengths of the relationship of change in available Cu with respect to other micronutrients (iron (Fe), manganese (Mn), and zinc (Zn)) were higher in the non-chelated system (R2: 0.68-0.94), compared to the chelated (R2: 0.42-0.81), with slopes of 0.40 (Cu-Fe), 0.31 (Cu-Mn), and 1.04 (Cu-Zn) in the non-chelated system and 0.26 (Cu-Fe), 0.22 (Cu-Mn), and 0.90 (Cu-Zn) in the chelated system. Reduction in the amount of available Cu was best described by the power function model (R2 = 0.91, SE = 0.081) in the non-chelated system and second-order model (R2 = 0.95, SE = 0.010) in the chelated system. The applications generated from this study could be used as tools for improved micronutrient management and also provide baseline data for future work in other semiarid/arid alkaline soils of the world. Findings are also more applicable to field settings, an improvement over related previous studies.

  9. Preparation and characterization of chitosan-grafted-poly(2-amino-4,5-pentamethylene-thiophene-3-carboxylic acid N'-acryloyl-hydrazide) chelating resin for removal of Cu(II), Co(II) and Ni(II) metal ions from aqueous solutions.

    Bekheit, M M; Nawar, N; Addison, A W; Abdel-Latif, D A; Monier, M

    2011-05-01

    The graft copolymerization of ethylacrylate (EA) onto chitosan initiated by potassium persulphate and Mohr's salt combined redox initiator system in limited aqueous medium was carried out in heterogeneous media. Moreover, modification of the grafted chitosan was carried out by reaction of the ester group (-COOEt) with 2-amino-4,5-pentamethylene-thiophene-3-carboxylic acid hydrazide which eventually produce chitosan-grafted-poly(2-amino-4,5-pentamethylene-thiophene-3-carboxylic acid N'-acryloyl-hydrazide) (chitosan-g-ATAH) chelating resin. The application of the modified resin for metal ion uptake was studied using Cu(2+), Co(2+) and Ni(2+) ions. The modified chelating resins were characterized using FTIR spectroscopy, SEM and X-ray diffraction. PMID:21277322

  10. New 111In labeling of IgG: 111In-oxine mediated chelation

    Current methods of 111In chelate conjugation labeling of antibodies expose the protein to pH 5-6 during 111In chelation. These conditions could be detrimental if the antibody is acid labile. We have successfully labeled human IgG via the cyclic anhydride of DPTA and 111In-oxyquinoline(oxine). Chelation was achieved at pH 6.9-8.4 and was complete within 1 min at room temperature. The chelation was sensitive to trace metal contamination on labware and in some reagents (including commercial 111In-oxine). (author)

  11. Chelating capture and magnetic removal of non-magnetic heavy metal substances from soil

    Liren Fan; Jiqing Song; Wenbo Bai; Shengping Wang; Ming Zeng; Xiaoming Li; Yang Zhou; Haifeng Li; Haiwei Lu

    2016-01-01

    A soil remediation method based on magnetic beneficiation is reported. A new magnetic solid chelator powder, FS@IDA (core-shell Fe3O4@SiO2 nanoparticles coated with iminodiacetic acid chelators), was used as a reactive magnetic carrier to selectively capture non-magnetic heavy metals in soil by chelation and removal by magnetic separation. FS@IDA was prepared via inorganic-organic and organic synthesis reactions that generated chelating groups on the surface of magnetic, multi-core, core-shel...

  12. Targeted Cleavage of HIV RRE RNA by Rev-Coupled Transition Metal Chelates

    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-dodec...

  13. Characterization of radionuclide-chelating agent complexes found in low-level radioactive decontamination waste. Literature review

    The US Nuclear Regulatory Commission is responsible for regulating the safe land disposal of low-level radioactive wastes that may contain organic chelating agents. Such agents include ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), picolinic acid, oxalic acid, and citric acid, and can form radionuclide-chelate complexes that may enhance the migration of radionuclides from disposal sites. Data from the available literature indicate that chelates can leach from solidified decontamination wastes in moderate concentration (1--100 ppm) and can potentially complex certain radionuclides in the leachates. In general it appears that both EDTA and DTPA have the potential to mobilize radionuclides from waste disposal sites because such chelates can leach in moderate concentration, form strong radionuclide-chelate complexes, and can be recalcitrant to biodegradation. It also appears that oxalic acid and citric acid will not greatly enhance the mobility of radionuclides from waste disposal sites because these chelates do not appear to leach in high concentration, tend to form relatively weak radionuclide-chelate complexes, and can be readily biodegraded. In the case of picolinic acid, insufficient data are available on adsorption, complexation of key radionuclides (such as the actinides), and biodegradation to make definitive predictions, although the available data indicate that picolinic acid can chelate certain radionuclides in the leachates

  14. Characterization of radionuclide-chelating agent complexes found in low-level radioactive decontamination waste. Literature review

    Serne, R.J.; Felmy, A.R.; Cantrell, K.J.; Krupka, K.M.; Campbell, J.A.; Bolton, H. Jr.; Fredrickson, J.K. [Pacific Northwest National Lab., Richland, WA (United States)

    1996-03-01

    The US Nuclear Regulatory Commission is responsible for regulating the safe land disposal of low-level radioactive wastes that may contain organic chelating agents. Such agents include ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), picolinic acid, oxalic acid, and citric acid, and can form radionuclide-chelate complexes that may enhance the migration of radionuclides from disposal sites. Data from the available literature indicate that chelates can leach from solidified decontamination wastes in moderate concentration (1--100 ppm) and can potentially complex certain radionuclides in the leachates. In general it appears that both EDTA and DTPA have the potential to mobilize radionuclides from waste disposal sites because such chelates can leach in moderate concentration, form strong radionuclide-chelate complexes, and can be recalcitrant to biodegradation. It also appears that oxalic acid and citric acid will not greatly enhance the mobility of radionuclides from waste disposal sites because these chelates do not appear to leach in high concentration, tend to form relatively weak radionuclide-chelate complexes, and can be readily biodegraded. In the case of picolinic acid, insufficient data are available on adsorption, complexation of key radionuclides (such as the actinides), and biodegradation to make definitive predictions, although the available data indicate that picolinic acid can chelate certain radionuclides in the leachates.

  15. White light emission from Mn2+ doped ZnS nanocrystals through the surface chelating of 8-hydroxyquinoline-5-sulfonic acid

    White light emitting semiconductor nanocrystals (NCs) have been successfully synthesized from 8-hydroxyquinoline-5-sulfonic acid (HQS) decorated manganese doped ZnS NCs through fine tuning the surface-coordination emission and dopant emission of the NC host. The HQS functionalized manganese doped ZnS NCs (QS-ZnS:Mn), with a cubic crystal structure, have the same diameter of about 4.0 nm as ZnS:Mn NCs without HQS. The intensity of the surface-coordination emission peak increased with increasing HQS content or augmenting excited wavelength. The emission of white light was achieved by carefully controlling the dosage of HQS in NCs and appropriately tuning the excited wavelength. The color coordinates (0.35, 0.34) for the efficient white light emitting NCs were very close to the ideal Commission Internationale de l'Eclairage (CIE) chromaticity coordinates for pure white light (0.33, 0.33). The photoluminescence (PL) decay study revealed that the white light emitting NCs exhibited maximum lifetime values at different emission peaks for different NC samples. The study results also indicated that the HQS molecules were attached to the surface of ZnS:Mn NCs in a single coordination fashion due to the steric hindrance effect of the special spherical surface of NCs, which made the QS-ZnS:Mn NCs possess stable and high fluorescent properties in different organic solvents as compared with the conventional small molecule complexes.

  16. Examining the fixation kinetics of chelated and non-chelated copper micronutrient and the applications to micronutrient management in semi-arid alkaline soils

    Udeigwe, T. K.; Eichmann, M. B.; Menkiti, M. C.

    2015-10-01

    The relationship between the deficiency of a nutrient in plants and its total concentration in the soil is complex. This study examined and compared the fixation and fixation kinetics of copper (Cu) in chelated (Ethylene diamine tetraacetic acid, EDTA) and non-chelated mixed systems of micronutrients in the semi-arid soils of the Southern High Plains, US using findings from Cu extraction studies and kinetic models. Approximately, 22 % more Cu was fixed in the non-chelated system within the first 14 days with only 7 % difference between the two systems by day 90. Findings suggest a decrease in the effectiveness of chelated micronutrient over time, highlighting the significance of timing even when chelated micronutrients are applied. The strengths of the relationship of change in available Cu with respect to other micronutrients [iron (Fe), manganese (Mn), and zinc (Zn)] were higher in the non-chelated system (R2: 0.68-0.94), compared to the chelated (R2: 0.42-0.81) with slopes of 0.40 (Cu-Fe), 0.31 (Cu-Mn), and 1.04 (Cu-Zn) in the non-chelated system and 0.26 (Cu-Fe), 0.22 (Cu-Mn), and 0.90 (Cu-Zn) in the chelated. Reduction in the amount of available Cu was best described by the power function model (R2 = 0.91, SE = 0.081) in the non-chelated system and second order model (R2 = 0.95, SE = 0.010) in the chelated system. The applications generated from this study could be used as tools for improved micronutrient management and also provide baseline data for future work in other semi-arid/arid alkaline soils of the world. Findings are also more applicable to field settings, an improvement over related previous studies.

  17. Sequestering agent for uranyl chelation: new bi-naphtyl ligands

    The synthesis of phosphonate, sulfocatecholamide (CAMS) and hydroxy-pyridinone (HOPO) bi-naphtyl ligands is presented. Their binding abilities for uranyl cation were determined by UV spectrophotometry in aqueous media versus pH. These titrations showed that the efficiency of these chelating agents depends on the nature of the chelating group. Each ligand shows a more or less pronounced affinity towards uranium. While the bis-phosphonate compound did not show any affinity towards the uranyl ion, the BINHOPO derivative exhibits significant affinity at acidic and neutral pH while the BINCAMS is more efficient at basic pH. (authors)

  18. Regularities in aluminium and indium chemisorption on chelating polymeric sorbents

    Complexation properties of synthesized polymer chelate sorbents: substituted of polystyrene-azo-pyrocatechol are investigated and correlations between pK'OH of functional groups of sorbents as well as pH50 values of chelation and constants of stability (lgKstab) are established for studying regularities of effect of structure and acid-base properties of functional groups of sorbents on the parameters of Al3+ and In3+ chemical sorption. Established correlations make it possible to predict the physicochemical parameters of sorbents and sorption of metal ions with the aim of separation and concentration of aluminium and indium micro account from the objects of different origin

  19. Chelating regularities in the series of chelating polymer sorbents and their complexes with vanadium, manganese, and chromium

    Physicochemical properties of new synthesized polymer chelation sorbents - substituted polystyrene-azo-salicylic acid are investigated. Correlations between pKCOOH of functional groups of sorbents with chelation pH50 and vanadium, manganese and chromium lgstab are established with the aim of studying interactions in the ion of element - sorbent system. Established correlations suggest physicochemical properties of the sorbents and sorption parameters of cations of metals with the aim of concentration and separation of V(5), Mn(2) and Cr(3) microamounts from natural and technical objects including environmental ones

  20. Overview of current chelation practices

    Y. Aydinok

    2011-12-01

    Full Text Available Deferoxamine (DFO is reference standard therapy for transfusional iron overload since the 1980s. Although it is a highly effective iron chelator, the compliance problem to subcutaneous administration of DFO remains as the major problem. The oral chelator Deferiprone (DFP has no marketing licence in North America, however, it has been licensed in India since 1994 and the European Union (EU granted marketing approval for DFP in 1999, specifically for patients with thalassemia major when DFO is inadequate, intolerable or unacceptable. There are still limited data available on the use of DFP in children between 6 and 10 years of age, and no data on DFP use in children under 6 years of age. Subsequently the oral chelator Deferasirox (DFX was approved by FDA and EMA for the treatment of patients with transfusional iron overload -older than 2 years of age- as first line therapy, in 2005 and 2006 respectively. The primary objective of iron chelation is to maintain body iron at safe levels at all times but once iron is accumulated, the objective of iron chelation is to reduce tissue iron to safe levels which is a slow process. The chelation regimen, dose and frequency of administration, of the chelator(s are mainly determined based on body iron burden, presence of myocardial iron and the transfusional iron loading rate. A proper monitoring of chelation is of importance for measuring the response rate to a particular regimen and providing dose adjustments to enhance chelation efficacy and to avoid toxicity. Efficacy of a chelation regimen may exhibit individual variability resulting from factors such as absorbtion and metabolism of the chelator. Tolerability and compliance are also individual variables effecting the response to chelation. Understanding of advantages and limitations of chelators, accurately determining chelation needs of patients with iron overload and designing individualized chelation regimens with less toxicity but optimum efficacy

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

    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

    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. Samarium-153 and lutetium-177 chelation properties of selected macrocyclic and acyclic ligands

    We describe a simple in vitro characterization of chelation that is useful when choosing an appropriate ligand-metal combination for clinical applications. These properties include the effect of concentration on chelation efficiency, time to maximum chelation, and stability in acidic and serum environments. The macrocyclic ligands nitro-DOTA and nitro-PADOTA, the acyclic ligands nitro-CHX-A-DTPA, nitro-MX-DTPA, DTPA, and a novel terpyridine ligand, TMT-amine, were evaluated as chelate complexes of both intermediate energy β-emitting lanthanides lutetium-177 and samarium-153. The data were compared to results obtained in a previously published study with yttrium-90. Acid lability, time to achieve maximum chelation, and stability in human serum are properties unique to each ligand-metal combination and should be evaluated prior to choosing an appropriate combination for therapeutic applications. Concentration dependence and duration of chelation are general properties of lanthanide and yttrium chelation that can be applied to an appropriate ligand-metal combination to achieve optimum chelation efficiencies

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

    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

  5. Targeted Catalytic Inactivation of Angiotensin Converting Enzyme by Lisinopril-Coupled Transition Metal Chelates

    Joyner, Jeff C.; Hocharoen, Lalintip; Cowan, J. A.

    2012-01-01

    A series of compounds that target reactive transition metal chelates to somatic Angiotensin Converting Enzyme (sACE-1) have been synthesized. Half maximal inhibitory concentrations (IC50) 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. Ethylenediamine-tetraacetic acid (EDTA), nitrilotriacetic acid (NTA), 1,4,7,10-tet...

  6. Iron chelation and multiple sclerosis

    Kelsey J. Weigel

    2014-01-01

    Full Text Available Histochemical and MRI studies have demonstrated that MS (multiple sclerosis patients have abnormal deposition of iron in both gray and white matter structures. Data is emerging indicating that this iron could partake in pathogenesis by various mechanisms, e.g., promoting the production of reactive oxygen species and enhancing the production of proinflammatory cytokines. Iron chelation therapy could be a viable strategy to block iron-related pathological events or it can confer cellular protection by stabilizing hypoxia inducible factor 1α, a transcription factor that normally responds to hypoxic conditions. Iron chelation has been shown to protect against disease progression and/or limit iron accumulation in some neurological disorders or their experimental models. Data from studies that administered a chelator to animals with experimental autoimmune encephalomyelitis, a model of MS, support the rationale for examining this treatment approach in MS. Preliminary clinical studies have been performed in MS patients using deferoxamine. Although some side effects were observed, the large majority of patients were able to tolerate the arduous administration regimen, i.e., 6–8 h of subcutaneous infusion, and all side effects resolved upon discontinuation of treatment. Importantly, these preliminary studies did not identify a disqualifying event for this experimental approach. More recently developed chelators, deferasirox and deferiprone, are more desirable for possible use in MS given their oral administration, and importantly, deferiprone can cross the blood–brain barrier. However, experiences from other conditions indicate that the potential for adverse events during chelation therapy necessitates close patient monitoring and a carefully considered administration regimen.

  7. Preparation, Spectroscopic Investigation and Biological Activity of New Mixed Ligand Chelates

    Preparation and investigation of new Co(II), Ni(II), Zn(II) and Cr(III) chelates with mixed ligands including Schiff base (L1) formed from the condensation of 4-dimethylaminobenzaldehyde with 2-aminophenol and anthranilic acid (L2) were studied. The obtained Schiff base and mixed ligand chelates were subjected to several physiochemical techniques, in terms of CHN elemental analyses, molar conductivity, magnetic moment measurements, infrared, proton nuclear magnetic resonance, electronic and mass spectra. The analytical data showed the formation of the Schiff base compound and the ratio of metal to ligands of the chelates are 1:1:1(M:L1:L2). The infrared spectral data exhibited that the used ligands behaving as bidentate ligands towards the metal ions. The proton nuclear magnetic resonance spectral data showed the signals of the active groups in the ligands which entered in chelation with Zn(II) metal ion. The electronic spectral results showed the existence of pie (phenyl ring) and n = pie (C=N) of the ligands and suggested the geometrical structures of the chelates. Meanwhile, the mass spectral data revealed the fragmentations of the Schiff base, anthranilic acid and their Ni(II) mixed ligand chelate has been preformed the only chelate conducted for justification. All the prepared mixed chelates were non-electrolyte in nature. The antibacterial activity of the Schiff base, anthranilic acid, metal salts and mixed ligand chelates were studied and found to be that mixed ligand chelates have the most biological activity in comparison to the free ligands and salts. (author)

  8. Binary and ternary chelates of scandium (III), Yttrium (III) and lanthanum (III) with ethyleneglycol-bis(β-aminoethylether)-tetraacetic acid as primary and substituted salicylic acids as secondary ligands

    Formation constants of binary and ternary complexes of the systems of the type: M-L and M-egta-L (M = scandium(III), yttrium(III) and lanthanum(III), egta = ethylene glycol-bis(β-aminoethylether)-tetra acetic acid, L = o-cresotic acid (o-ca), m-cresotic acid (m-ca), 5-chlorosalicyclic acid(csa), and 3,5-dibromosalicylic acid (dbsa)) have been determined pH-metrically at 25deg and μ = 0.1M (KNO3) in 50% (v/v) aqueous-ethanol medium. The order of stabilities of ternary complexes has been compared with those of corresponding binary complexes, and results discussed on the basis of coulombic interactions. (auth.)

  9. Extraction of Heavy Metals from Sludge Using Biodegradable Chelating Agent N,N-bis(carboxymethyl) Glutamic Acid Tetrasodium%生物可降解螯合剂谷氨酸 N,N -二乙酸四钠对污泥中重金属萃取效率的研究

    吴青; 崔延瑞; 汤晓晓; 杨慧娟; 孙剑辉

    2015-01-01

    N, N-bis ( carboxymethyl) glutamic acid tetrasodium ( GLDA), a novel biodegradable and green chelating agent, has excellent metal chelating ability. Batch experiment was conducted to study the extraction process of Cd, Ni, Cu and Zn in industrial sludge using GLDA. The effects of contact time, pH of the system, content of chelating agent were investigated, and the forms of heavy metals in sludge pre- and post-extraction using the modified BCR sequential extraction procedure were studied. The results showed that GLDA was effective for cadmium extraction in sludge. Several heavy metals could be effectively extracted under the condition of pH 4 and molar ratio of chelating agent to total heavy metal 3: 1. Residual fraction took the largest fraction in Zn, which caused the low extraction efficiency of this metal. Chelating properties were related not only to contact time, pH, chelating agent’s concentration, and stability constant but also to species distribution of metals.%谷氨酸 N,N -二乙酸四钠(GLDA)具有较强金属螯合能力,是新一代生物可降解绿色螯合剂。通过分批提取实验对GLDA 去除工业污泥中 Cd、 Ni、 Cu、 Zn 的萃取过程进行研究,考察了萃取时间、萃取体系 pH 值、螯合剂用量等因素对重金属萃取效果的影响,并采用修正的 BCR 连续提取法分析萃取前后污泥中重金属的形态。结果表明, GLDA 对污泥中 Cd 具有良好的去除效果;体系在 pH =4,螯合剂与重金属总量摩尔比为3:1的条件下,多种重金属取得最佳萃取效果; Zn 主要以残渣态存在,导致该金属萃取率低;螯合能力不仅与萃取时间,萃取体系 pH 值,螯合剂用量,螯合常数等因素有关,而且还与金属的形态分布有关。

  10. Improved paramagnetic chelate for molecular imaging with MRI

    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

  11. Improved paramagnetic chelate for molecular imaging with MRI

    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.

  12. Development of new metal chelates for animal nutrition and of analytical methods for their quantitative determination and quality control

    Beltrami, Diego

    2009-01-01

    The growing interest for mineral integration to increase mineral bioavalability brought researchers to re-examine accurately the impact that complexes and chelates can have for food industry. In fact, the so-called organic or chelate mineral forms, in particular those associated with amino acids, peptides or other organic molecules, afforded encouraging results in different in vivo tests on animals of economic interest fed with fodder containing minerals in the form of chelates. Moreover, it ...

  13. The Influence of the Chelating Agent Nitrilotriacetic Acid on Promotion of Hydrodesulfurization Activity by Co in CoMo Catalysts Prepared on Al2O3, C, and ZrO2 Supports

    Kaluža, L. (Luděk); Zdražil, M. (Miroslav); Gulková, D. (Daniela); Vít, Z. (Zdeněk)

    2013-01-01

    The chelating agent NTA systematically increased the promotion effect of Co in the sulfided catalysts in comparison to samples prepared without NTA from ammonium heptamolybdate and cobalt nitrate. The promotion effect was increased by the factor 1.13-1.58.

  14. Heavy metal displacement in chelate-irrigated soil during phytoremediation

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

    2003-03-01

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

  15. Luminescent lanthanide chelates and methods of use

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

    1997-01-01

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

  16. f-Element Ion Chelation in Highly Basic Media

    A large body of data has been collected over the last fifty years on the chemical behavior of f-element ions. The ions undergo rapid hydrolysis reactions in neutral or basic aqueous solutions that produce poorly understood oxide-hydroxide species; therefore, most of the fundamental f-element solution chemistry has allowed synthetic and separations chemists to rationally design advanced organic chelating ligands useful for highly selective partitioning and separation of f-element ions from complex acidic solution matrices. These ligands and new examples under development allow for the safe use and treatment of solutions containing highly radioactive species. This DOE/EMSP project was undertaken to address the following fundamental objectives: (1) study the chemical speciation of Sr and lanthanide (Ln) ions in basic aqueous media containing classical counter anions found in waste matrices; (2) prepare pyridine N-oxide phosphonates and phosphonic acids that might act as selective chelators for Ln ions in model basic pH waste streams; (3) study the binding of the new chelators toward Ln ions and (4) examine the utility of the chelators as decontamination and dissolution agents under basic solution conditions. The project has been successful in attacking selected aspects of the very difficult problems associated with basic pH solution f-element waste chemistry. In particular, the project has (1) shed additional light on the initial stages of Ln ion sol-gel-precipitate formulation under basic solution conditions; (2) generated new families of pyridine phosphonic acid chelators; (3) characterized the function of the chelators and (4) examined their utility as oxide-hydroxide dissolution agents. These findings have contributed significantly to an improved understanding of the behavior of Ln ions in basic media containing anions found in typical waste sludges as well as to the development of sludge dissolution agents. The new chelating reagents are easily made and could be

  17. Iron chelation and multiple sclerosis

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

    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 prote...

  18. Some Linguistic Detail on Chelation

    Haworth, Daniel T.

    1998-01-01

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

  19. Chelator induced phytoextraction and in situ soil washing of Cu

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

  20. Chelator induced phytoextraction and in situ soil washing of Cu

    Kos, Bostjan; Lestan, Domen

    2004-11-01

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

  1. Use of Fricke solution modified with dyes for dosimetry in phototherapeutic treatments; Uso da solucao Fricke modificada com corantes para futura dosimetria em tratamentos fototerapeuticos

    Almeida, Mayara Gabriella Oliveira de; Nascimento, Rizia Keila; Vieira, Rafaela Etelvina de Amorim; Souza, Vivianne Lucia Bormann, E-mail: mayaradqf@hotmail.com, E-mail: riziakeila@hotmail.com, E-mail: rafaelarodriguesss@hotmail.com, E-mail: vlsouza@cnen.gov.br [Centro Regional de Ciencias Nucleares do Nordeste (CRCN-NE/CNEN-PE), Recife (Brazil)

    2014-07-01

    Dyes and pigments (photosensitizers) are characterized by their ability to absorb visible light, and to participate in photochemical reactions. These colors are used in medicine in the dose recommended for use in photodynamic therapy (PDT). There are lasers that can meet most of the phototherapeutic agents and are capable of providing light of considerable power with precision on the injured tissue. The use of light emitting diodes (LEDs) have become feasible, thus reducing the cost of the procedures. The Dosimetry Laboratory Chemistry of the CRCN-NE/Brazilian CNEN has worked with some likely dye use in phototherapy treatments, including: methylene blue, malachite green and toluidine blue. A volume of 2.6 ml of the dosimeters was transferred to test tubes and these were irradiated with LED 24, 48, 72 and 96 acrylic simulator 110 mm x 110 mm x 80 mm at a distance of 6.5 cm from reading light source of the irradiated samples was performed on a spectrophotometer. Having obtaining excellent correlations (above 0.97) to the dosimeter calibration curves. Suggests that the dosimeter can be applied to perform a quality control in photodynamic therapy. However, further experiments should be performed before a wide application of this technique. A volume of 2.6 ml of the dosimeters was transferred to test tubes and these were irradiated with LED 24, 48, 72 and 96 acrylic simulator 110 mm x 110 mm x 80 mm at a distance of 6.5 cm from reading light source of the irradiated samples was performed on a spectrophotometer. Having obtaining excellent correlations (above 0.97) to the dosimeter calibration curves. Suggests that the dosimeter can be applied to perform a quality control in photodynamic therapy. However, further experiments should be performed before a wide application of this technique.

  2. Synergistic Activities of an Efflux Pump Inhibitor and Iron Chelators against Pseudomonas aeruginosa Growth and Biofilm Formation

    Liu, Yang; Yang, Liang; Molin, Søren

    2010-01-01

    The efflux pump inhibitor phenyl-arginine-beta-naphthylamide (PA beta N) was paired with iron chelators 2,2'-dipyridyl, acetohydroxamic acid, and EDTA to assess synergistic activities against Pseudomonas aeruginosa growth and biofilm formation. All of the tested iron chelators synergistically...

  3. Studies on the chelation of aluminium for biological application

    Potentiometric determinations of the strength of chelation of aluminium(III) by citrate and 3-carboxy-1,5-pentanedioic acid have been made at 37,0 plus minus 0,1 degree Celsius and I = 150 mmol dm-3 NaCl. From these results, the citrate complex is inferred to be tridentate with coordination through the two terminal carboxyl groups and the central hydroxyl group. This structure is confirmed by 13C nuclear magnetic resonance

  4. Effect of chelating agents on the distribution of monoclonal antibodies in mice

    The potential for altering the biodistribution of radiolabel from gallium- and indium-labeled mouse monoclonal antibodies was investigated in mice using metal chelating agents. The chelating agents used were desferrioxamine (DFO), diethylenetriaminepentaacetic acid (DTPA), ethylenediamine-di (O-hydroxyphenylacetic acid) (EDHPA), and 2,2' dipyridyl (DIPY). The mouse monoclonal antibody LICR-LON-M8 was labeled with 111In after conjugation to DTPA, and with 67Ga after conjugation to DFO. All the chelating agents except DIPY altered the biodistribution of [67Ga]citrate and [111In]citrate but did not affect the 48-hr tissue uptake of label from [111In]DTPA-M8 or [67Ga]DFO-M8, confirming the in vivo stability of the antibody conjugates. Label fixed in the tissues was inaccessible to the chelating agents, indicating that they will not be suitable for reducing the high background liver radioactivity in patients undergoing scanning with indium-labeled antibodies

  5. Status of chelation research: a review

    The current status of research on the removal of actinide elements from the body is reviewed. Items occurring prior to 1980 include evidence for fetal toxicity from Ca-DTPA, the FDA approval of Zn-DTPA for human therapy, the mixed ligand fiasco, and the abrupt wipeout of chelation funding. New concepts that should be explored include improvements in removing radioactivity from lung and bone, the effectiveness of DTPA inside cells, simultaneous therapy with mobilizing agents and chelating agents, prolonging the retention of chelating agents within the body, the oral administration of chelating agents, the effectiveness of LICAM and other new chelating agents, the safety of decorporation procedures, and the effectiveness of chelation therapy on reducing the risk from radionuclide-induced cancer. Some physicians give DTPA by intravenous injection, a safe procedure that should be officially sanctioned

  6. In vitro test system for evaluating the effectiveness of chelators

    A procedure has been devised to test in vitro the relative effectiveness of chelating agents for the elimination of radiotoxins from specified, in vivo labeled endogenous ligands. The report describes the elimination of 239Pu from liver homogenates by various chelating agents. The effectivity of a homologous series of polyaminocarboxylic acids (PACA's) was compared to that of certain derivatives containing a straight alkyl group. The effectiveness of these lipophilic PACA's appears to depend on the chain length of the substituent. Lipophilic chelons were more effective in chelating 239Pu than unsubstituted PACA's. Combination of EDTA or DTPA with a number of oligodentate complexing agents were also tested. With EDTA, the removal of Pu was enhanced by p-aminosalicylic acid (PAS), Desferioxamine B (DFOA) and strongly enhanced by 4,5-Dihydroxy-m-benzenedisulfonic acid (Tiron). Only DFOA showed enhanced removal with DTPA. The different behavior of the mixed ligand treatments can be explained by either formation of binary complexes or action on different biological Pu-pools

  7. Role of chelates in treatment of cancer

    Tripathi Laxmi

    2007-01-01

    Full Text Available Chelates are used in cancer as cytotoxic agent, as radioactive agent in imaging studies and in radioimmunotherapy. Various chelates based on ruthenium, copper, zinc, organocobalt, gold, platinum, palladium, cobalt, nickel and iron are reported as cytotoxic agent. Monoclonal antibodies labeled with radioactive metals such as yttrium-90, indium-111 and iodine-131 are used in radioimmunotherapy. This review is an attempt to compile the use of chelates as cytotoxic drugs and in radioimmunotherapy.

  8. Iron Chelation Therapy in Myelodysplastic Syndromes

    Giuseppe Saglio; Daniela Cilloni; Emanuela Messa

    2010-01-01

    Myelodysplastic syndromes (MDS) are a heterogeneous disorder of the hematopoietic stem cells, frequently characterized by anemia and transfusion dependency. In low-risk patients, transfusion dependency can be long lasting, leading to iron overload. Iron chelation therapy may be a therapeutic option for these patients, especially since the approval of oral iron chelators, which are easier to use and better accepted by the patients. The usefulness of iron chelation in MDS patients is still unde...

  9. Beliefs about chelation among thalassemia patients

    Trachtenberg Felicia L; Mednick Lauren; Kwiatkowski Janet L; Neufeld Ellis J; Haines Dru; Pakbaz Zahra; Thompson Alexis A; Quinn Charles T; Grady Robert; Sobota Amy; Olivieri Nancy; Horne Robert; Yamashita Robert

    2012-01-01

    Abstract Background Understanding patients’ views about medication is crucial to maximize adherence. Thalassemia is a congenital blood disorder requiring chronic blood transfusions and daily iron chelation therapy. Methods The Beliefs in Medicine Questionnaire (BMQ) was used to assess beliefs in chelation in thalassemia patients from North America and London in the Thalassemia Longitudinal Cohort (TLC) of the Thalassemia Clinical Research Network (TCRN). Chelation adherence was based on patie...

  10. Diagnostic chelation challenge with DMSA: a biomarker of long-term mercury exposure?

    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 afte...

  11. Optimization of chelators to enhance uranium uptake from tailings for phytoremediation.

    Jagetiya, Bhagawatilal; Sharma, Anubha

    2013-04-01

    A greenhouse experiment was set up to investigate the ability of citric acid (CA), oxalic acid (OA), nitrilotriacetic acid (NTA) and EDTA for phytoremediation of uranium tailings by Indian mustard [Brassica juncea (L.) Czern. et Coss]. Uranium tailings were collected from Umra mining region and mixed with 75% of garden soil which yielded a 25:75 mixture. Prepared pots were divided into four sets and treated with following different concentrations - 0.1, 0.5, 2.5 and 12.5 mmol kg(-1) soil additions for each of the four chelators. Control pots which were not treated with chelators. Experiments were conducted in completely randomized block design with triplicates. The optimum concentrations of these chelators were found on the basis of biomass production, tolerance and accumulation potential. The data collected were expressed statistically. EDTA produced maximum growth depression whereas, minimum occurred in the case of NTA. Maximum U uptake (3.5-fold) in the roots occurred at 2.5 mmol of CA, while NTA proved to be the weakest for the same purpose. Severe toxicity in the form of reduced growth and plant death was recorded at 12.5 mmol of each chelator. Minimum growth inhibition produced by chelators occurred in NTA which was followed by OA, moderate in CA and maximum was traced in EDTA applications. Chelator strengthened U uptake in the present study follows the order: CA>EDTA>OA>NTA. PMID:23267730

  12. Chelating capture and magnetic removal of non-magnetic heavy metal substances from soil

    Fan, Liren; Song, Jiqing; Bai, Wenbo; Wang, Shengping; Zeng, Ming; Li, Xiaoming; Zhou, Yang; Li, Haifeng; Lu, Haiwei

    2016-02-01

    A soil remediation method based on magnetic beneficiation is reported. A new magnetic solid chelator powder, FS@IDA (core-shell Fe3O4@SiO2 nanoparticles coated with iminodiacetic acid chelators), was used as a reactive magnetic carrier to selectively capture non-magnetic heavy metals in soil by chelation and removal by magnetic separation. FS@IDA was prepared via inorganic-organic and organic synthesis reactions that generated chelating groups on the surface of magnetic, multi-core, core-shell Fe3O4@SiO2 (FS) nanoparticles. These reactions used a silane coupling agent and sodium chloroacetate. The results show that FS@IDA could chelate the heavy metal component of Cd, Zn, Pb, Cu and Ni carbonates, lead sulfate and lead chloride in water-insoluble salt systems. The resulting FS@IDA-Cd and FS@IDA-Pb chelates could be magnetically separated, resulting in removal rates of approximately 84.9% and 72.2% for Cd and Pb, respectively. FS@IDA could not remove the residual heavy metals and those bound to organic matter in the soil. FS@IDA did not significantly alter the chemical composition of the soil, and it allowed for fast chelating capture, simple magnetic separation and facilitated heavy metal elution. FS@IDA could also be easily prepared and reprocessed.

  13. Generation, Fractionation, and Characterization of Iron-Chelating Protein Hydrolysate from Palm Kernel Cake Proteins.

    Zarei, Mohammad; Ghanbari, Rahele; Tajabadi, Naser; Abdul-Hamid, Azizah; Bakar, Fatimah Abu; Saari, Nazamid

    2016-02-01

    Palm kernel cake protein was hydrolyzed with different proteases namely papain, bromelain, subtilisin, flavourzyme, trypsin, chymotrypsin, and pepsin to generate different protein hydrolysates. Peptide content and iron-chelating activity of each hydrolysate were evaluated using O-phthaldialdehyde-based spectrophotometric method and ferrozine-based colorimetric assay, respectively. The results revealed a positive correlation between peptide contents and iron-chelating activities of the protein hydrolysates. Protein hydrolysate generated by papain exhibited the highest peptide content of 10.5 mM and highest iron-chelating activity of 64.8% compared with the other hydrolysates. Profiling of the papain-generated hydrolysate by reverse phase high performance liquid chromatography fractionation indicated a direct association between peptide content and iron-chelating activity in most of the fractions. Further fractionation using isoelectric focusing also revealed that protein hydrolysate with basic and neutral isoelectric point (pI) had the highest iron-chelating activity, although a few fractions in the acidic range also exhibited good metal chelating potential. After identification and synthesis of papain-generated peptides, GGIF and YLLLK showed among the highest iron-chelating activities of 56% and 53%, whereas their IC50 were 1.4 and 0.2 μM, respectively. PMID:26720491

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

    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.

  15. Treatment of some radioactive wastes by using new chelating membranes

    The preparation of chelating membranes containing nitrile and carboxylic acid as functional groups was investigated. The modification of such membranes by chemical treatments to produce significant changes in their properties was studied. This modification results in a higher rate of exchange and higher capacity. The applicability of such modified membranes in the removal of Co-60 and Cs-137 from their wastes were tested. The dependence of these radioactive nuclides uptake on the time and degree of grafting for H CI-, NH2OH-and KOH-treated membranes was investigated. It was found that the adsorption rate and capacity were higher for KOH-treated membrane than those for the NH2OH and H CI treated ones. The prepared grafted membranes have a good affinity towards the adsorption or chelation with Co-60 and Cs-137. This result may make such prepared materials acceptable for practicable use in some radioactive waste treatments and recovery

  16. Conformational study of aromatic ketones: chemical shift reagents: uranium chelates

    A series of benzophenones, 2-benzoyl thiophenes and 2-benzoyl pyridines, all substituted at the benzene ring by an amino acid chain, have been synthesised with the object of examining to what extent the site of the aminoacid chain and the site and nature of the other substituents modify the electronic structure of the molecule and the orientation of each ring with respect to the plane of the carbonyl group. In the second part a study of paramagnetic cations, in particular of uranium, which is able to form stable chelates with beta-diketones was carried out to study their complexing power. The chelates studied are the (hexafluoropentanedionate)4U, the (heptafluorodimethyloctanedionate)4U and the (trifluorophenylbutanedionate)4U

  17. Chelation studies involving decontamination of light lanthanides by polyaminopolycarboxylic

    The present thesis constitutes chelation studies involving decontamination of light lanthanides, cobalt , and uranium with 2,2-bis-acryloyliminomethylene- acid (BAETA) using the spectrophotometric method. the work carried out aimed to clear up the effectiveness of BAETA as a decontaminating agent for radioactive nuclides from human body . the thesis includes a general introduction , outlines the aim of work and contains three main chapters . the results of the work are discussed at the end of the thesis. the first chapter deals with a comprehensive survey of the relevant literature. this includes the metabolism and toxicity of cerium, uranium, cobalt and Ln+3 elements, general methodologies of internal decontamination, choice and effectiveness of chelating agents

  18. Multidentate Terephthalamidate And Hydroxypyridonate Ligands: Towards New Orally Active Chelators

    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 59Fe, 238Pu, and 241Am 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.

  19. Metal ions, Alzheimer's disease and chelation therapy.

    Budimir, Ana

    2011-03-01

    In the last few years, various studies have been providing evidence that metal ions are critically involved in the pathogenesis of major neurological diseases (Alzheimer, Parkinson). Metal ion chelators have been suggested as potential therapies for diseases involving metal ion imbalance. Neurodegeneration is an excellent target for exploiting the metal chelator approach to therapeutics. In contrast to the direct chelation approach in metal ion overload disorders, in neurodegeneration the goal seems to be a better and subtle modulation of metal ion homeostasis, aimed at restoring ionic balance. Thus, moderate chelators able to coordinate deleterious metals without disturbing metal homeostasis are needed. To date, several chelating agents have been investigated for their potential to treat neurodegeneration, and a series of 8-hydroxyquinoline analogues showed the greatest potential for the treatment of neurodegenerative diseases. PMID:21406339

  20. Importance of iron chelation therapy

    A. Varoğlu

    2011-01-01

    It is necessary to remember that today patients have different options of chelation treatment, as desferrioxamine, deferiprone and deferasirox are available. However, a patient has to be compliant with treatments. They have always to remember that too much iron causes different complications and could be a barrier for a definitive cure from thalassemia. 由于出现了去铁胺、去铁酮和去铁斯若等药物,病人现在可以选择不同的螯合治疗方式。 然而,病人必须适应这几种治疗方式。 他们必须时刻记住太多的铁元素会引发多种并发症,并对地中海贫血的彻底治疗造成阻碍。...

  1. High-performance liquid chromatography method for ferric iron chelators using a post-column reaction with Calcein Blue.

    Ariga, Tomoko; Ito, Kyoko; Imura, Yuki; Yoshimura, Etsuro

    2015-03-15

    Iron (Fe) is an essential element for higher plants, which take it up from the soil at the root surface and transport it to shoots through the xylem. Fe(III) chelators, such as organic acids and phytosiderophores, play important roles in the acquisition and transportation of Fe(III). Therefore, a selective and sensitive method for analyzing Fe(III) chelators is required to study the many Fe-related physiological mechanisms in plants. A novel analytical approach employing a high-performance liquid chromatography post-column method with fluorescence detection was developed to separate and detect Fe(III) chelators. This method takes advantage of the quenching of the fluorescence of Calcein Blue (CB) that occurs with the formation of an Fe(III)-CB complex and the dequenching that occurs with the release of CB as a result of competition for Fe(III) between CB and an Fe(III) chelator. This simple experimental method does not require complicated pretreatments and can selectively detect Fe(III) chelators according to their Fe(III)-chelating ability. The detection limit for citric acid using this method was 72pmol. Furthermore, this method can also detect unknown Fe(III) chelators that exhibit a high affinity for Fe(III). The method was evaluated with xylem sap of barley, which was shown to contain several Fe(III) chelators. PMID:25658515

  2. The fabrication and study of metal chelating stationary phases for the high performance separation of metal ions

    The preparation and characterisation of chelating sorbents suitable for the high efficiency separation of trace metals in complex samples, using a single column and isocratic elution, is described. Hydrophobic, neutral polystyrene divinylbenzene resins were either impregnated with chelating dyes or dynamically modified with heterocyclic organic acids, using physical adsorption and chemisorption processes respectively. A hydrophilic silica substrate was covalently bonded with a chelating aminomethylphosphonic acid group, to assess the chelating potential of this molecule. These substrates were characterised in terms of metal retention capability (selectivity coefficients and capacity factors), separation performance, column efficiency and suitability for analytical applications. Chelating molecules with different ligand groups were found to have unique selectivity patterns dependant upon the conditional stability constants of the chelate. Other factors, including mobile phase constituents - complexing agents, ionic strength and pH, column length and column capacity were additionally investigated to examine their effect upon the separation profiles achieved. The promising metal separation abilities illustrated by a number of these chelating columns were exploited for the determination of trace toxic metals in complex sample matrices using High Performance Chelation Ion Chromatography (HPCIC). This included the determination of beryllium in a certified stream sediment, uranium in seawater and a certified stream sediment, and cadmium, lead and copper in a certified rice flour. The results for each analysis fell within the certified limits, and reproducibility was good. The optimisation of post column detection systems using chromogenic ligands additionally gave good detection limits for the metals in each separation system. (author)

  3. Mixed Intramolecular Hydrogen Bonding in Dihydroxythiophene-based Units and Boron and Technetium Chelation

    Three novel potential metal ion chelating units have been synthesized and characterized: 5-hexylcarbamoyl- 3,4-dihydroxythiophene-2-carboxylic acid methyl ester (5), 3-benzyloxy-4-hydroxythiophene-2,5-dicarboxylic acid bis-hexylamide (6), and 3,4-dihydroxythiophene-2,5-dicarboxylic acid bis-hexylamide (7). The crystal structure of 6 was obtained and suggests the presence of three distinct intramolecular hydrogen bonds, namely [Namide-H···O] [O-H···Oamide] and [Namide-H···S]. Boron chelation with 5, 6 and 7 through the use of BF3, B(OH)3 or B(OMe)3 was probed by 1H, 11B, and 13C NMR spectroscopy. Technetium (I) chelation with 5, 6 and 7 was also studied via HPLC elutions using [99mTc(CO)3(OH2)3]+

  4. 氨基酸螯合锌在奶山羊肠道消化吸收规律的研究%Digestion and Absorption of Zinc Amino Acid Chelate in the Intestinal Tract of Dairy Goats

    杨改青; 朱河水; 王林枫; 贺翠婷; 张振; 高建伟; 邵其斌; 冯亚强; 孙波

    2011-01-01

    本试验旨在研究氨基酸螯合锌(Zn-AA)在奶山羊体内的消化吸收规律及其在饲粮中的适宜添加水平.试验选取2.5~3.0岁,体重40~45 kg的关中奶山羊母羊6只,安装永久性瘤胃、十二指肠及回肠瘘管,首先从瘤胃灌注40 mg/kg的Zn-AA溶液,分别在灌注后的24、48、72、96、120、144和168 h采集十二指肠食糜、回肠食糜、粪样和血样,测定样品中锌含量,计算锌在小肠和全肠道消化率,检测血清锌水平,确定最佳采样时间.在此基础上,分别灌注0、20、60、80、100和200 mg/kg的Zn-AA溶液,测定不同水平的Zn-AA在小肠和全肠道的消化率及血清锌水平.结果表明,Zn-AA全肠道消化率在48和96 h分别出现吸收高峰,120 h后Zn-AA在小肠、全肠道的消化率和血清锌水平基本平衡并保持稳定;不同时间和水平的Zn-AA在全肠道的消化率均高于小肠,小肠是Zn-AA吸收的主要部位,大肠对Zn-AA也有不同程度地吸收;60 mg/kg时Zn-AA在全肠道消化率和血清中水平均达到最大值.研究得出,成年奶山羊饲粮中Zn-AA的最适宜添加水平为60 mg/kg,小肠是Zn-AA消化的主要部位,大肠对Zn-AA也表现出较强的消化吸收能力.%This trial was conducted to study the digestion and absorption of zinc amino acid chelate (Zn-AA) in intestinal tract of dairy goats and to determine the optimal supplemental level of Zn-AA in the diet. Six Guanzhong daffy goats aged 2. 5 to 3.0 years old with the body weight of 40 to 45 kg were selected and fixed with permanent fistulas in rumen, duodenum and ileum. At the beginning of the trial, 40 mg/kg Zn-AA solution was infused into the rumen, and samples were collected at 24, 48, 96, 120, 144 and 168 h after infusion. Digesta samples from the duodenum and ileum, and feces samples were collected to detect the zinc levels and calculate the digestibility in the small intestine, entire intestine and large intestine. At the same time, blood samples were

  5. Targeted cleavage of HIV RRE RNA by Rev-coupled transition metal chelates.

    Joyner, Jeff C; Cowan, J A

    2011-06-29

    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-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) were linked to a lysine side chain 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 Fe(2+), Co(2+), Ni(2+), and Cu(2+) 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 K(D) values ranging from ~0.2 to 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 to 4.9 nM/min but were optimal for Cu(2+)-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 those of the two principal co-reagents for metal-promoted formation of

  6. Chelating agents in pharmacology, toxicology and therapeutics

    The proceedings contain 71 abstracts of papers. Fourteen abstracts were inputted in INIS. The topics covered include: the effects of chelating agents on the retention of 63Ni, 109Cd, 203Hg, 144Ce, 95Nb and the excretion of 210Po, 63Ni, 48V, 239Pu, 241Am, 54Mn; the applications of tracer techniques for studies of the efficacy of chelation therapy in patients with heart and brain disorders; and the treatment of metal poisoning with chelating agents. (J.P.)

  7. Tumor targeting of radiolabeled antibodies using HYNIC chelate

    There is an increasing interest in the use of labeled antibodies for diagnosis of cancers as well as for therapy. Various radiolabeling methods have been used in order to obtain better tumor specific targeting for detection and therapy. It was generally used to tumor targeted immunotherapy and immunodetection that lym-1, mouse monoclonal antibody, was specific binding to surface antigen of Raji. The 3E8 antibody was produced from humanized anti-TAG-72 monoclonal antibody (AKA) by amino acid change in 95-99 residues of heavy chain complementary determinant regions (HCDRs) 3 using phage displayed library technology. In this study, we are investigating the usefulness of HYNIC chelate as a bifunctional chelating agent in radioimmunodetecton of tumor. Two types of antibodies, Lym-1 and 3E8, were used for the conjugation with HYNIC chelate. Lym-1 and 3E8 are specific antibodies to surface antigen of Non-Hogkin's lymphoma and TAG-72 antigen of colorectal carcinoma, respectively. We prepare HYNIC-antibody conjugates, determine radiolabeling yield with 99mTc and evaluate tumor targeting in tumor bearing nude mice model

  8. Enhancing Potentially Plant-Available Lead Concentrations in Contaminated Residential Soils Using a Biodegradable Chelating Agent

    Andra, S.; Datta, R.; Sarkar, D.; Saminathan, S.

    2007-12-01

    Chelation of heavy metals is an important factor in enhancing metal solubility and, hence, metal availability to plants to promote phytoremediation. In the present study, we compared the effects of application of a biodegradable chelating agent, namely, ethylenediaminedisuccinic acid (EDDS) on enhancing plant available form of lead (Pb) in Pb-based paint contaminated residential soils compared to that of a more commonly used, but non-biodegradable chelate, i.e., ethylenediaminetetraacetic acid (EDTA). Development of a successful phytoremediation model for metals such as Pb depends on a thorough understanding of the physical and chemical properties of the soil, along with the optimization of a chelate treatment to mobilize Pb from `unavailable' pools to potentially plant available fraction. In this context, we set out to perform batch incubation experiments to investigate the effectiveness of the two aforementioned chelates in enhancing plant available Pb at four different concentrations (0, 5, 10 and 15 mM/kg soil) and three treatment durations (0, 10 and 30 days). We selected 12 contaminated residential soils from two major metropolitan areas (San Antonio, TX and Baltimore, MD) with varying soil physico-chemical properties - the soils from San Antonio were primarily alkaline and those from Baltimore were typically acidic. Total soil Pb concentrations ranged between 256 mg/kg and 4,182 mg/kg. Our results show that both chelates increased the solubility of Pb, otherwise occluded in the complex soil matrix. For both EDTA and EDDS, the exchangeable concentrations of soil Pb also increased with increase in chelate concentration and incubation time. The most effective treatment was 15 mM chelate kg-1 soil incubated for 30 days, which caused many fold increase in potentially plant available Pb (a combination of the soluble and exchangeable fractions) relative to the unamended controls. Step wise multiple linear regression analysis using chelate-extractable Pb and soil

  9. Mathematical modelling of the effects of aerobic and anaerobic chelate biodegradation on actinide speciation

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

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

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

  11. Chelating Tendencies of Bioactive Aminophosphonates

    Kiss, Tamas; Lázár, István; Kafarski, Pawel

    1994-01-01

    The metal-binding abilities of a wide variety of bioactive aminophosphonates, from the simple aminoethanephosphonic acids to the rather large macrocyclic polyaza derivatives, are discussed with special emphasis on a comparison of the analogous carboxylic acid and phosphonic acid systems. Examples are given of the biological importance of metal ion – aminophosphonate interactions in living systems, and also of their actual and potential applicability in medicine.

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

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

    2014-01-01

    Purpose of review EDTA chelation therapy has been in off-label use for the treatment of atherosclerosis. We review the results of the first large-scale randomized trial of this treatment. Recent findings The trial to assess chelation therapy was a $30 million National Institutes of Health-funded study of the safety and efficacy of EDTA-based chelation infusions in 1708 post-myocardial infarction (MI) patients. The trial to assess chelation therapy demonstrated a significant (P = 0.035) 18% re...

  13. New Regeneration process of heavy metals loaded chelating resin

    Menoud, P.; Cavin, L.; Renken, A.

    2000-01-01

    An alternative to the classical acid-base regeneration of chelating resins loaded with heavy metals is investigated. The new process consists in recovering the heavy metals with recyclable soluble complexing agents. The semiclosed reactor includes a fixed bed and a stirred tank. A three-parameter model, which implies a double equilibrium in series, is introduced. When less than 10 % of the metal is still fixed on the resin at the end of the desorption, a simplified form of the model with two ...

  14. Fluorescence enhancement by chelation of Eu3+ and Tb3+ ions in sol-gels

    Chelation of rare-earth (RE) ions is investigated as a means of enhancing the optical properties of RE-doped silica sol-gels. Two chelating agents--2,6-pyridine-dicarboxylic acid (PDC) and 3-pyridinepropionic acid (PPA) and two different synthesis techniques are studied. Eu(PDC) gels exhibit intense 5D0→7F2 fluorescence in the red under UV excitation and long fluorescence lifetimes compared to Eu(PPA) gels and to gels without a chelating agent. This behavior indicates that the PDC molecule remains associated with the Eu after incorporation into the gel. Similar behavior is seen for 5D4→7F5 green fluorescence in Tb(PDC)

  15. Current Use of Chelation in American Health Care

    Wax, Paul M.

    2013-01-01

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

  16. A study of intracellular iron metabolism using pyridoxal isonicotinoyl hydrazone and other synthetic chelating agents

    Rabbit reticulocytes with a high level of non-heme radioiron induced by preincubation with isonicotinic acid hydrazide and transferrin-bound 59Fe, were reincubated with various synthetic chelating agents and the amount of radioiron released from the cells was determined. Some substances, especially derivatives of pyridoxal or 2-hydroxybenzaldehyde and isonicotinic acid hydrazide or benzhydrazide, were found to mobilize significantly iron from 59Fe-labelled reticulocytes. Iron mobilizaiton from reticulocytes by pyridoxal isonicotinoyl hydrazone requires ATP to be produced by cells and is completely blocked by low temperatute (40C). Although the effect of desferrioxamine is also prevented by low temperature, modest iron mobilization due to this chelator seems to occur independently of ATP production in reticulocytes. Pyridoxal isonicotinoyl hydrazone mobilized iron mainly from mitochondria and in part also from ferritin. Although 2,2'-bipyridine seems to enter reticulocyte mitochondria and bind iron there, this chelator is not able to relaease iron either from mitochondria or from the cells. Reticulocytes with a high level of non-heme radioiron are envisaged as a useful system for testing biological effectiveness of various iron chelators. Pyridoxal isonicotinoyl hydrazone was shown to be an effective in vivo chelator since its adminstration to mice decreased 59Fe radioactivity in liver, spleen and kidney. (Auth.)

  17. Assessing the Impact of EDTA Chelating Effect on some Macro- and Microminerals in Prussian Carp (Carassius Gibelio) Tissues

    Marioara Nicula; Iosif Gergen; Monica Harmanescu; Ionut Banatean-Dunea; Adela Marcu; Eliza Simiz; Tiberiu Polen; Mihai Lunca

    2011-01-01

    Chelators are used in chemical analysis, in medical aplications, as water softeners, as decontamination agents on radioactive surfaces and they are ingredients in many commercial products such as shampoos and food preservatives. Such a synthetic chelator is EDTA (ethylenediaminetetraacetic acid). It is considered one of the tools that promises to control the heavy metal pollution in aquaculture. EDTA attaches itself to heavy metals and carries the metals from the fish body. EDTA can also slow...

  18. Predictors of DMSA chelatable lead, tibial lead, and blood lead in 802 Korean lead workers

    Todd, A; Lee, B; Lee, G.; Ahn, K; Moshier, E; Schwartz, B.

    2001-01-01

    OBJECTIVES—To examine the interrelations among chelatable lead (by dimercaptosuccinic acid, DMSA), tibial lead, and blood lead concentrations in 802 Korean workers with occupational exposure to lead and 135 employed controls with only environmental exposure to lead.
METHODS—This was a cross sectional study wherein tibial lead, DMSA chelatable lead, and blood lead were measured. Linear regression was used to identify predictors of the three lead biomarkers, evaluating the influence of age, job...

  19. Improvement of Oxidative and Metabolic Parameters by Cellfood Administration in Patients Affected by Neurodegenerative Diseases on Chelation Treatment

    Alessandro Fulgenzi; Rachele De Giuseppe; Fabrizia Bamonti; Maria Elena Ferrero

    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)....

  20. Copper Chelation in Alzheimer's Disease Protein

    Rose, Frisco; Hodak, Miroslav; Bernholc, Jerry

    2013-03-01

    Alzheimer's disease (AD) is a neurodegenerative disorder affecting millions of people in the U.S. AD is primarily characterized at the cellular level by densely tangled fibrils of amyloid- β protein. These protein clusters have been found in association with elevated levels of multiple transition metals, with copper being the most egregious. Interestingly, metal chelation has shown promise in attenuating the symptoms of AD in recent clinical studies. We investigate this process by constructing an atomistic model of the amyloid- β-copper complex and profile the energetic viability in each of its subsequent disassociation stages. Our results indicate that five energetic barriers must be overcome for full metal chelation. The energy barriers are biologically viable in the presence water mediated bond and proton transfer between the metal and the protein. We model the chelation reaction using a consecutive path nudged elastic band method implemented in our ab initio real-space multi-grid code to obtain a viable sequence. This reaction model details a physically consistent explanation of the chelation process that could lead to the discovery of more effective chelation agents in the treatment of AD.

  1. Metal Ions Extraction with Glucose Derivatives as Chelating Reagents in Supercritical Carbon Dioxide

    Guo Chen YANG; Hai Jian YANG

    2006-01-01

    A series of glucose derivatives have been used as chelating reagents to extract metal ions in supercritical carbon dioxide. With perfluoro-1-octanesulfonic acid tetraethylammonium salt as additive, glucose derivatives were selective for Sr2+ and Pb2+ extraction in supercritical carbon dioxide.

  2. Leaching heavy metals in municipal solid waste incinerator fly ash with chelator/biosurfactant mixed solution.

    Xu, Ying; Chen, Yu

    2015-07-01

    The chelator [S,S]-ethylene diamine disuccinic acid, citric acid, and biosurfactant saponin are selected as leaching agents. In this study, the leaching effect of saponin mixed with either ethylene diamine disuccinic acid or citric acid on the levels of copper, zinc, lead, and cadmium in municipal solid waste incinerator fly ash is investigated. Results indicate that saponin separately mixed with ethylene diamine disuccinic acid and citric acid exhibits a synergistic solubilisation effect on copper, zinc, lead, and cadmium leaching from fly ash. However, saponin and ethylene diamine disuccinic acid mixed solution exhibits a synergistic solubilisation effect that is superior to that of a saponin and citric acid mixed solution. The extraction rate of heavy metal in fly ash leached with a saponin and chelator mixed solution is related to the pH of the leaching solution, and the optimal range of the pH is suggested to be approximately neutral. After leaching with a saponin and chelator mixed solution, copper, zinc, lead, and cadmium contents significantly decreased (p leaching concentrations of copper, zinc, lead, and cadmium in treated fly ash are in accordance with Standard for Pollution Control on the Security Landfill Site for Hazardous Wastes GB18598-2001. PMID:26185165

  3. Phytoremediation of Cr(VI) by Spirodela polyrrhiza (L.) Schleiden employing reducing and chelating agents.

    Bala, Rajni; Thukral, Ashwani K

    2011-01-01

    Phytoremediation of Cr(VI) by Spirodela polyrrhiza in binary combinations with low molecular weight organic compounds (LMWOCs) with a reducing or chelating potential, viz., ascorbic acid, citric acid, tartaric acid, oxalic acid, lactic acid, and glycerol was studied in Cr(VI) containing hydroponic media. Significant increase in the relative dry weight of plants with respect to Cr(VI) treated controls was observed with ascorbic acid and glycerol. The uptake of chromium by S. polyrrhiza followed Michaelis-Menten kinetics of active ion uptake. Interaction between Cr and ascorbic acid, oxalic acid, and lactic acid decreased Cr uptake, whereas citric acid, glycerol, and tartaric acid increased it. Supplementation of LMWOCs to Cr(VI) containing media decreased the MDA content of the plants. Multiple regression models revealed that LMWOCs decrease lipid peroxidation independently, as well as that induced by Cr(VI). It was found that superoxide dismutase (SOD), guaiacol peroxidase (GPX), and catalase (CAT) activities were increased significantly in plants growing in media containing Cr(VI). The study established that lactic acid, citric acid, ascorbic acid, and glycerol were most effective in increasing the Cr(VI) phytoremediating potential of S. polyrrhiza and LMWOCs with reducing or chelating properties decrease Cr(VI) stress in S. polyrrhiza. PMID:21598777

  4. Trypanotoxic activity of thiosemicarbazone iron chelators.

    Ellis, Samuel; Sexton, Darren W; Steverding, Dietmar

    2015-03-01

    Only a few drugs are available for treating sleeping sickness and nagana disease; parasitic infections caused by protozoans of the genus Trypanosoma in sub-Saharan Africa. There is an urgent need for the development of new medicines for chemotherapy of these devastating diseases. In this study, three newly designed thiosemicarbazone iron chelators, TSC24, Dp44mT and 3-AP, were tested for in vitro activity against bloodstream forms of Trypanosoma brucei and human leukaemia HL-60 cells. In addition to their iron chelating properties, TSC24 and Dp44mT inhibit topoisomerase IIα while 3-AP inactivates ribonucleotide reductase. All three compounds exhibited anti-trypanosomal activity, with minimum inhibitory concentration (MIC) values ranging between 1 and 100 µM and 50% growth inhibition (GI50) values of around 250 nM. Although the compounds did not kill HL-60 cells (MIC values >100 µM), TSC24 and Dp44mT displayed considerable cytotoxicity based on their GI50 values. Iron supplementation partly reversed the trypanotoxic and cytotoxic activity of TSC24 and Dp44mT but not of 3-AP. This finding suggests possible synergy between the iron chelating and topoisomerase IIα inhibiting activity of the compounds. However, further investigation using separate agents, the iron chelator deferoxamine and the topoisomerase II inhibitor epirubicin, did not support any synergy for the interaction of iron chelation and topoisomerase II inhibition. Furthermore, TSC24 was shown to induce DNA degradation in bloodstream forms of T. brucei indicating that the mechanism of trypanotoxic activity of the compound is topoisomerase II independent. In conclusion, the data support further investigation of thiosemicarbazone iron chelators with dual activity as lead compounds for anti-trypanosomal drug development. PMID:25595343

  5. Chelating Properties of Peptides from Red Seaweed Pyropia columbina and Its Effect on Iron Bio-Accessibility.

    Cian, Raúl E; Garzón, Antonela G; Ancona, David Betancur; Guerrero, Luis Chel; Drago, Silvina R

    2016-03-01

    The aim of this work was to evaluate copper-chelating, iron-chelating and anticariogenic activity of peptides obtained by enzymatic hydrolysis of P. columbina protein concentrate and to study the effects of chelating peptides on iron bio-accessibility. Two hydrolyzates were obtained from P. columbina protein concentrate (PC) using two hydrolysis systems: alkaline protease (A) and alkaline protease + Flavourzyme (AF). FPLC gel filtration profile of PC shows a peak having molecular weight (MW) higher than 7000 Da (proteins). A and AF hydrolyzates had peptides with medium and low MW (1013 and 270 Da), respectively. Additionally, AF presented free amino acids with MW around 82 Da and higher content of His and Ser. Peptides from AF showed the highest chelating properties measured as copper-chelating activity (the lowest β-carotene oxidation rate: R o ; 0.7 min(-1)), iron-chelating activity (33 %), and phosphorous and Ca(2+) release inhibition (87 and 81 %, respectively). These properties could indicate antioxidant properties, promotion of iron absorption and anticariogenic activity, respectively. In fact, hydrolyzates promoted iron dialyzability (≈16 %), values being higher than that found for P. columbina seaweed. Chelating peptides from both hydrolyzates can maintain the iron in a soluble and bio-accessible form after gastrointestinal digestion. PMID:26860526

  6. Synthesis, characterization and in vitro anticancer evaluations of two novel derivatives of deferasirox iron chelator.

    Salehi, Samie; Saljooghi, Amir Sh; Shiri, Ali

    2016-06-15

    Iron (Fe) chelation therapy was initially designed to alleviate the toxic effects of excess Fe evident in Fe-overload diseases. However, the novel toxicological properties of some Fe chelator-metal complexes have shifted significant attention to their application in cancer chemotherapy. The present study investigates the new role of deferasirox as an anticancer agent due to its ability to chelate with iron. Because of aminoacids antioxidant effect, deferasirox and its two novel amino acid derivatives have been synthesized through the treatment of deferasirox with DCC as well as glycine or phenylalanine methyl ester. All new compounds have been characterized by elemental analysis, FT-IR NMR and mass spectrometry. Therefore, the cytotoxicity of these compounds was screened for antitumor activity against some cell lines using cisplatin as a comparative standard by MTT assay and Flow cytometry. The impact of iron in the intracellular generation of reactive oxygen species was assessed on HT29 and MDA-MB-231 cells. The potential of the synthesized iron chelators for their efficacy to protect cells against model oxidative injury induced was compared. The reactive oxygen species intracellular fluorescence intensity were measured and the result showed that the reactive oxygen species intensity after iron incubation increased while after chelators incubation the reactive oxygen species intensity were decreased significantly. Besides, the effect of the synthesized compounds on mouse fibroblast cell line (L929) was simultaneously evaluated as control. The pharmacological results showed that deferasirox and its two novel aminoacid derivatives were potent anticancer agents. PMID:27090924

  7. Synthesis characterization and structural investigations on lanthanon(III) chelates of tridentate Schiff bases

    The dissociation constants of O-(N-pyrrole-2-methyl imino) propanoic acid [H2PP] and O-(N-furan-2-chloroimino)ethane thiol [HFT], stability constants and thermodynamic parameters of their chelates with La(II), Ce(III), Nd(III), Sm(III), Gd(III), Tb(III), Dy(III), Ho(III) and Er(III) have been determined by Calvin-Bjerrum pH-titration techniques as modified by Irving and Rossotti in 30% (v/v) alcohol-water medium (μ=0.01 M, 0.05 M and 0.1 M NaClO4) at 25, 35 and 45degC. Solid Ln(III) chelates were characterized by molecular mass, elemental analysis, magnetic moment, conductance, 1H NMR, electronic and IR spectra. HFT-Ln(III)-chelates show 1:3 metal-ligand stoichiometry whereas H2PP-Ln(III)-chelates show 1:2 stoichiometry. Physico-chemical studies such as magnetic, IR, NMR etc. also support these geometries. HFT and H2PP are respectively monoprotic and biprotic tridentates. In view of the above facts a trigonal tricapped pyramidal and octahedral geometries can be assigned to the HFT-Ln(III) and H2PP-Ln(III) chelates respectively. (author). 15 refs., 4 tabs., 1 fig

  8. Heavy metal induced oxidative stress & its possible reversal by chelation therapy.

    Flora, S J S; Mittal, Megha; Mehta, Ashish

    2008-10-01

    Exposure to heavy metals is a common phenomenon due to their environmental pervasiveness. Metal intoxication particularly neurotoxicity, genotoxicity, or carcinogenicity is widely known. This review summarizes our current understanding about the mechanism by which metalloids or heavy metals (particularly arsenic, lead, cadmium and mercury) induce their toxic effects. The unifying factor in determining toxicity and carcinogenicity for all these metals is the generation of reactive oxygen and nitrogen species. The toxic manifestations of these metals are caused primarily due to imbalance between pro-oxidant and antioxidant homeostasis which is termed as oxidative stress. Besides these metals have high affinity for thiol groups containing enzymes and proteins, which are responsible for normal cellular defense mechanism. Long term exposure to these metals could lead to apoptosis. Signaling components affected by metals include growth factor receptors, G-proteins, MAP kinases and transcription factors. Chelation therapy with chelating agents like calcium disodium ethylenediamine tetra acetic acid (CaNa(2)EDTA), 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 metal poisoning. Despite many years of research we are still far away from effective treatment against toxicity caused due to exposure to heavy metals/metalloids. The treatment with these chelating agents is compromised with number of serious side-effects. Studies show that supplementation of antioxidants along-with a chelating agent prove to be a better treatment regimen than monotherapy with chelating agents. This review attempts a comprehensive account of recent developments in the research on heavy metal 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

  9. Recent developments centered on orally active iron chelators

    Robert Hider

    2014-09-01

    Full Text Available Over the past twenty years there has been a growing interest in the orally active iron chelators, deferiprone and deferasirox, both have been extensively studied. The ability of these compounds to mobilize iron from the heart and endocrine tissue has presented the clinician with some advantages over desferrioxamine, the first therapeutic iron chelator. Other orally active iron chelators are currently under development. The critical features necessary for the design of therapeutically useful orally active iron chelators are presented in this review, together with recent studies devoted to the design of such chelators. This newly emerging range of iron chelators will enable clinicians to apply iron chelation methodology to other disease states and to begin to design personalized chelation regimes.

  10. Development of an upconverting chelate assay

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

    2005-04-01

    We report progress on performing a cell-based assay for the detection of EGFR on cell surfaces by using upconverting chelates. An upconversion microscope has been developed for performing assays and testing optical response. A431 cells are labeled with europium DOTA and imaged using this upconverting microscope.

  11. Questions and Answers on Unapproved Chelation Products

    ... it Email Print The U.S. Food and Drug Administration (FDA) advises consumers to be wary of so-called “chelation” products that are marketed over-the-counter (OTC) to prevent or treat diseases. Companies are marketing unapproved OTC chelation therapy products to ...

  12. Analysis and identification of chelators and degradation products in radioactive mixed hazardous wastes by derivatization GC/MS

    The characterization of radioactive mixed hazardous waste tanks has received increased interest because of the need to understand the chemistry of the waste prior to disposal or remediation. Organic chelators such as ethylenediaminetetraacetic acid (EDTA), hydroxyethylenediaminetriacetic acid (HEDTA), and their degradation products are present in many of the waste tanks at Hanford. In the case of Hanford waste tank 101-SY, the thermal and radiolytical degradation of chelators have been linked to the production of hydrogen gas. Analysis of chelators is not amenable to gas chromatography (GC) without prior derivatization. Previously, the authors have reported on derivatization of chelator standards using BF3/methanol, diazomethane, silylation, and butyl esterification. The BF3/methanol derivatization method showed the most promise to be applied to radioactive mixed waste. In this study, the authors applied the BF3/methanol derivatization GC/MS method to an actual waste sample from waste tank 101-SY. Electron impact and chemical ionization were utilized to identify the components in this methyl ester chelator fraction. In addition, high resolution mass spectrometry was used to obtain accurate mass measurements of identical components found in a synthetic chelator sample (non-radioactive) made to simulate tank 101-SY

  13. Ethylenediaminetetraacetic acid in endodontics

    Mohammadi, Zahed; Shalavi, Sousan; Jafarzadeh, Hamid

    2013-01-01

    Ethylenediaminetetraacetic acid (EDTA) is a chelating agent can bind to metals via four carboxylate and two amine groups. It is a polyamino carboxylic acid and a colorless, water-soluble solid, which is widely used to dissolve lime scale. It is produced as several salts, notably disodium EDTA and calcium disodium EDTA. EDTA reacts with the calcium ions in dentine and forms soluble calcium chelates. A review of the literature and a discussion of the different indications and considerations for...

  14. Overview of chelation recommendations for thalassaemia and sickle cell disease

    Banu Kaya

    2014-12-01

    Full Text Available The long term consequences of iron toxicity are mostly reversible with effective iron chelation therapy. Recommendations for use of chelation therapy in transfusion dependent thalassaemia (TDT, sickle cell disease (SCD and non transfusion dependent thalassaemia (NTDT continue to evolve as our knowledge and clinical experience increases. Improved chelation options including drug combinations and a better understanding of condition specific factors may help to improve efficiency of chelation regimens and meet the needs of patients more effectively.

  15. Overview of chelation recommendations for thalassaemia and sickle cell disease

    Banu Kaya

    2014-01-01

    The long term consequences of iron toxicity are mostly reversible with effective iron chelation therapy. Recommendations for use of chelation therapy in transfusion dependent thalassaemia (TDT), sickle cell disease (SCD) and non transfusion dependent thalassaemia (NTDT) continue to evolve as our knowledge and clinical experience increases. Improved chelation options including drug combinations and a better understanding of condition specific factors may help to improve efficiency of chelation...

  16. Development of Iron-Chelating Poly(ethylene terephthalate) Packaging for Inhibiting Lipid Oxidation in Oil-in-Water Emulsions.

    Johnson, David R; Tian, Fang; Roman, Maxine J; Decker, Eric A; Goddard, Julie M

    2015-05-27

    Foods such as bulk oils, salad dressings, and nutritionally fortified beverages that are susceptible to oxidative degradation are often packaged in poly(ethylene terephthalate) (PET) bottles with metal chelators added to the food to maintain product quality. In the present work, a metal-chelating active packaging material is designed and characterized, in which poly(hydroxamic acid) (PHA) metal-chelating moieties were grafted from the surface of PET. Biomimetic PHA groups were grafted in a two-step UV-initiated process without the use of a photoinitiator. Surface characterization of the films by attenuated total reflective Fourier transform infrared spectroscopy (ATR-FTIR) and scanning electron microscopy (SEM) suggested successful grafting and conversion of poly(hydroxyethyl acrylate) (PHEA) to PHA chelating moieties from the surface of PET. Colorimetric (ferrozine) and inductively coupled plasma mass spectroscopy (ICP-MS) assays demonstrated the ability of PET-g-PHA to chelate iron in a low-pH (3.0) environment containing a competitive metal chelator (citric acid). Lipid oxidation studies demonstrated the antioxidant activity of PET-g-PHA films in inhibiting iron-promoted oxidation in an acidified oil-in-water (O/W) emulsion model system (pH 3.0). Particle size and ζ-potential analysis indicated that the addition of PET-g-PHA films did not affect the physical stability of the emulsion system. This work suggests that biomimetic chelating moieties can be grafted from PET and effectively inhibit iron-promoted degradation reactions, enabling removal of metal-chelating additives from product formulations. PMID:25985711

  17. COMPARATIVE STUDY OF CHELATION VALUE OF SEVENTEEN PERCENT SELF DEVELOPED AND COMMERCIALLY AVAILABLE ROOT CANAL LUBRICANTS

    Ingale Satish Dinkarrao; Kankariya Rajendra

    2013-01-01

    The main objective of this study is to compare chelation values of 17% self developed & commercially available root canal Lubricants or dental chelating gels as well as to see whether their performance depends on the chelation value or not. The Chelating agent bounds Ca2+ ions of the smear layer & the extent of chelate formation between chelating agent and metal ion is nothing but Chelation Value. Sodium carbonate indicator method is used for determinations of chelation value. Commercially av...

  18. [Remediation of Cu-Pb-contaminated loess soil by leaching with chelating agent and biosurfactant].

    Liu, Xia; Wang, Jian-Tao; Zhang, Meng; Wang, Li; Yang, Ya-Ti

    2013-04-01

    Because of its strong chelation, solubilization characteristics, the chelating agents and biosurfactant are widely used in remediation of heavy metals and organic contaminated soils. Ethylenediamine tetraacetic acid (EDTA), citric acid (CIT) and dirhamnolipid (RL2) were selected as the eluent. Batch experiments and column experiments were conducted to investigate the leaching effect of the three kinds of eluent, as well as the mixture of biosurfactant and chelating agent for Cu, Pb contaminated loess soil. The results showed that the leaching efficiencies of different eluent on Cu, Pb contaminated loess soil followed the sequence of EDTA > CIT > RL2. At an eluent concentration of 0.02 mol x L(-1), the Cu leaching efficiency was 62.74% (EDTA), 52.28% (CIT) and 15.35% (RL2), respectively; the Pb leaching efficiency was 96.10% (EDTA), 23.08% (CIT) and 14.42% (RL2), respectively. When the concentration of RL2 was 100 CMC, it had synergistic effects on the other two kinds of chelating agent in Cu leaching, and when the concentration of RL2 was 200 CMC, it had antagonism effects. The effect of RL2 on EDTA in Pb leaching was similar to that in Cu leaching. Pb leaching by CIT was inhibited in the presence of RL2. EDTA and CIT could effectively remove Cu and Pb in exchangeable states, adsorption states, carbonate salts and organic bound forms; RL2 could effectively remove Cu and Pb in exchangeable and adsorbed states. PMID:23798147

  19. Economically dissolving barium sulfate scale with a chelating agent

    Richardson, E.A.; Scheuerman, R.E.

    1977-06-21

    A composition is described for dissolving a barium sulfate scale from a subterranean or other relatively remote location into which fluid can be flowed. Fluid is flow-flowed into the remote location so that a stream of fluid contacts and flows along the surface of the scale. The composition and flow rate of the fluid are adjusted so that (1) the scale is contacted by a stream of aqueous solution in which each portion contains enough dissolved aminopolyacetic acid salt chelating agent to dissolve barium sulfate, and (2) substantially all upstream portions of the scale are contacted by a succession of portions of the aqueous liquid which are substantially unsaturated with respect to dissolved barium-chelant complex. (5 claims)

  20. f-Element Ion Chelation in Highly Basic Media - Final Report

    Paine, R.T.

    2000-12-12

    A large body of data has been collected over the last fifty years on the chemical behavior of f-element ions. The ions undergo rapid hydrolysis reactions in neutral or basic aqueous solutions that produce poorly understood oxide-hydroxide species; therefore, most of the fundamental f-element solution chemistry has allowed synthetic and separations chemists to rationally design advanced organic chelating ligands useful for highly selective partitioning and separation of f-element ions from complex acidic solution matrices. These ligands and new examples under development allow for the safe use and treatment of solutions containing highly radioactive species. This DOE/EMSP project was undertaken to address the following fundamental objectives: (1) study the chemical speciation of Sr and lanthanide (Ln) ions in basic aqueous media containing classical counter anions found in waste matrices; (2) prepare pyridine N-oxide phosphonates and phosphonic acids that might act as selective chelator s for Ln ions in model basic pH waste streams; (3) study the binding of the new chelators toward Ln ions and (4) examine the utility of the chelators as decontamination and dissolution agents under basic solution conditions. The project has been successful in attacking selected aspects of the very difficult problems associated with basic pH solution f-element waste chemistry. In particular, the project has (1) shed additional light on the initial stages of Ln ion sol-gel-precipitate formulation under basic solution conditions; (2) generated new families of pyridine phosphonic acid chelators; (3) characterized the function of the chelators and (4) examined their utility as oxide-hydroxide dissolution agents. These findings have contributed significantly to an improved understanding of the behavior of Ln ions in basic media containing anions found in typical waste sludges as well as to the development of sludge dissolution agents. The new chelating reagents are easily made and could be

  1. f-Element Ion Chelation in Highly Basic Media - Final Report

    A large body of data has been collected over the last fifty years on the chemical behavior of f-element ions. The ions undergo rapid hydrolysis reactions in neutral or basic aqueous solutions that produce poorly understood oxide-hydroxide species; therefore, most of the fundamental f-element solution chemistry has allowed synthetic and separations chemists to rationally design advanced organic chelating ligands useful for highly selective partitioning and separation of f-element ions from complex acidic solution matrices. These ligands and new examples under development allow for the safe use and treatment of solutions containing highly radioactive species. This DOE/EMSP project was undertaken to address the following fundamental objectives: (1) study the chemical speciation of Sr and lanthanide (Ln) ions in basic aqueous media containing classical counter anions found in waste matrices; (2) prepare pyridine N-oxide phosphonates and phosphonic acids that might act as selective chelator s for Ln ions in model basic pH waste streams; (3) study the binding of the new chelators toward Ln ions and (4) examine the utility of the chelators as decontamination and dissolution agents under basic solution conditions. The project has been successful in attacking selected aspects of the very difficult problems associated with basic pH solution f-element waste chemistry. In particular, the project has (1) shed additional light on the initial stages of Ln ion sol-gel-precipitate formulation under basic solution conditions; (2) generated new families of pyridine phosphonic acid chelators; (3) characterized the function of the chelators and (4) examined their utility as oxide-hydroxide dissolution agents. These findings have contributed significantly to an improved understanding of the behavior of Ln ions in basic media containing anions found in typical waste sludges as well as to the development of sludge dissolution agents. The new chelating reagents are easily made and could be

  2. Pentaarylcyclopentadiene und chirale Ruthenium-Chelat-Komplexe

    Kanthak, Matthias

    2010-01-01

    Die Synthese von mono-ortho-funktionalisierten Pentaphenylcyclopentadienen gelang durch eine Abwandlung der klassischen Tetracyclon-Route. Durch die Umsetzung der funktionalisierten Cyclopentadiene mit Ru3(CO)12 als Metallquelle konnten entsprechende Ruthenium-Komplexe erhalten werden. Die geeignete Wahl der Substituenten an der Phenylgruppe erlaubte die Bildung von Chelat-Komplexen mit chirotopem Metallzentrum. Enantiomerenreine Oxazolin-Seitenarme führten zu diastereomerenreinen...

  3. Federal Regulation of Unapproved Chelation Products

    Lee, Charles E.

    2013-01-01

    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 ar...

  4. Removal of iron by chelation with molecularly imprinted supermacroporous cryogel.

    Çimen, Duygu; Göktürk, Ilgım; Yılmaz, Fatma

    2016-06-01

    Iron chelation therapy can be used for the selective removal of Fe(3+) ions from spiked human plasma by ion imprinting. N-Methacryloyl-(L)-glutamic acid (MAGA) was chosen as the chelating monomer. In the first step, MAGA was complexed with the Fe(3+) ions to prepare the precomplex, and then the ion-imprinted poly(hydroxyethyl methacrylate-N-methacryloyl-(L)-glutamic acid) [PHEMAGA-Fe(3+)] cryogel column was prepared by cryo-polymerization under a semi-frozen temperature of - 12°C for 24 h. Subsequently, the template, of Fe(3+) ions was removed from the matrix by using 0.1 M EDTA solution. The values for the specific surface area of the imprinted PHEMAGA-Fe(3+) and non-imprinted PHEMAGA cryogel were 45.74 and 7.52 m(2)/g respectively, with a pore size in the range of 50-200 μm in diameter. The maximum Fe(3+) adsorption capacity was 19.8 μmol Fe(3+)/g cryogel from aqueous solutions and 12.28 μmol Fe(3+)/g cryogel from spiked human plasma. The relative selectivity coefficients of ion-imprinted cryogel for Fe(3+)/Ni(2+) and Fe(3+)/Cd(2+) were 1.6 and 4.2-fold greater than the non-imprinted matrix, respectively. It means that the PHEMAGA-Fe(3+) cryogel possesses high selectivity to Fe(3+) ions, and could be used many times without significantly decreasing the adsorption capacity. PMID:25727711

  5. Decorporation of metal ions by chelating agents

    Simple model designs to simulate the effect of therapeutical chelating agents on the behaviour of metals in mammal organisms with and without excretion have been derived and analytical solutions given for the corresponding differential equations. The possibilities of these models in the short-term description of plasma kinetics of various metals, the competition of the therapeutical ligands with proteins for the metal and of the metabolism of chelating agents were tested and the properties applying extreme conceivable parameters were analyzed. The simple models were successsively expanded in logical sequence, so that it was possible to qualitatively well describe over a long period of time, the metallic kinetics in plasma, organs and urine, the retention of the ligands and their effect on the metal excretion. Two suggestions were given to describe the so-called after-effect, an increased excretion of the metal at times when the ligand is almost completely excreted and their different behaviour after injecting the metal chelate is given. Calculations on the therapy with several ligand data as well as on dose fractionation are described resting on the ratios in the plutonium-239 chosen model parameters and the determining mechanisms analyzed. (orig./MG)

  6. Conjugates of monoclonal antibodies and chelating polymers

    The primary purpose of protein modification with chelating polymers is to prepare monoclonal antibodies labeled with heavy metal isotopes (alpha-, beta-, and gamma-emitting metal and paramagnetic ions for NMR tomography). Conventional binding of metals to proteins via chelating agents directly coupled to proteins does not permit binding of a large number of metal atoms per protein molecule without causing alterations in the specific properties of the protein molecules. On the other hand, metal ion binding to proteins via intermediate chelating polymers should permit binding of several dozens of the metal atoms per protein molecule without affect the specific properties adversely. Moreover, the biodistribution and clearance rates can be regulated by varying the polymer properties. Modified antibodies may be used successfully in nuclear and NMR diagnostic applications and in radiotherapy. Possible applications of this approach shall be demonstrated with monoclonal antibody R11D10 for visualization of acute myocardial infarction. Use of this modification with other monoclonal antibodies is also discussed. The chemistry of protein modification with these polymers is presented

  7. IRON CHELATION THERAPY IN THALASSEMIA SYNDROMES

    Paolo Cianciulli

    2009-06-01

    Full Text Available Transfusional hemosiderosis is a frequent complication in patients with transfusion dependent chronic diseases such as  thalassemias and severe type of sickle cell diseases. As there are no physiological mechanisms to excrete the iron contained in transfused red cells (1 unit of blood contains approximately 200 mg of iron the excess of iron is stored in various organs. Cardiomyopathy is the most severe complication covering more than 70% of the causes of death of thalassemic patients. Although the current reference standard iron chelator deferoxamine (DFO has been used clinically for over four decades, its effectiveness is limited by a demanding therapeutic regimen that leads to poor compliance. Despite poor compliance, because of the inconvenience of subcutaneous infusion, DFO improved considerably the survival and quality of life of patients with thalassemia. Deferiprone since 1998 and Deferasirox since 2005 were licensed for clinical use. The oral chelators have a better compliance because of oral use, a comparable efficacy to DFO in iron excretion and probably a better penetration to myocardial cells. Considerable increase in iron excretion was documented with combination therapy of DFO and Deferiprone. The proper use of the three chelators will improve the prevention and treatment of iron overload, it will reduce  complications, and improve survival and quality of life of transfused patients

  8. Comparative Assessment of Complex Stabilities of Radiocopper Chelating Agents by a Combination of Complex Challenge and in vivo Experiments.

    Litau, Shanna; Seibold, Uwe; Vall-Sagarra, Alicia; Fricker, Gert; Wängler, Björn; Wängler, Carmen

    2015-07-01

    For (64) Cu radiolabeling of biomolecules to be used as in vivo positron emission tomography (PET) imaging agents, various chelators are commonly applied. It has not yet been determined which of the most potent chelators--NODA-GA ((1,4,7-triazacyclononane-4,7-diyl)diacetic acid-1-glutaric acid), CB-TE2A (2,2'-(1,4,8,11-tetraazabicyclo[6.6.2]hexadecane-4,11-diyl)diacetic acid), or CB-TE1A-GA (1,4,8,11-tetraazabicyclo[6.6.2]hexadecane-4,11-diyl-8-acetic acid-1-glutaric acid)--forms the most stable complexes resulting in PET images of highest quality. We determined the (64) Cu complex stabilities for these three chelators by a combination of complex challenge and an in vivo approach. For this purpose, bioconjugates of the chelating agents with the gastrin-releasing peptide receptor (GRPR)-affine peptide PESIN and an integrin αv β3 -affine c(RGDfC) tetramer were synthesized and radiolabeled with (64) Cu in excellent yields and specific activities. The (64) Cu-labeled biomolecules were evaluated for their complex stabilities in vitro by conducting a challenge experiment with the respective other chelators as challengers. The in vivo stabilities of the complexes were also determined, showing the highest stability for the (64) Cu-CB-TE1A-GA complex in both experimental setups. Therefore, CB-TE1A-GA is the most appropriate chelating agent for *Cu-labeled radiotracers and in vivo imaging applications. PMID:26011290

  9. The Mechanism of Cumene Peroxidation Catalyzed by Cobalt(Ⅱ)-Chelated Copolymer

    Cheng-Chien Wang; Hui-Chun Chen; Chuh-Yean Chen; Chuh-Yung Chen

    2005-01-01

    @@ 1Introduction The functionalised polymers, especially for chelating polymer, have been employed to considerable effects in organic synthesis for several decades. The use of polymer groups as ligands permits the ligand surroundings to be varied and regulation of the catalytic properties of the complexes because of the flexibility of the polymer chains, their ability to adopt various conformations, and the possibility of creating various spatial distributions of metal centers immobilized on the polymer chains[1,2]. In our recently studies[3-5], the chelating copolymer with imino-diacetic acid chelating group in the polymer side chain was manufactured, and which can increase effectively amount of the chelating group within the polymer. Meanwhile, the high catalysis performance in organic synthesis had also been proved via benzaldehyde and cumene peroxidation. For cumene peroxidation,it is hardly to find such a simple catalyst with high conversion and selectivity due to hydroperoxide decomposition by a radical mechanism. The cumene peroxidation by catalyst system and its reaction mechanism as well as the kinetic study are popularly investigated object for many researchers[6-9]. However, the reaction mechanism still does not clear owing to the by-products will be produced following the different catalysts used.

  10. Isolation and Utilization of Corn Cobs Hemisellulose as Chelating Agent for Lead Ions

    Corn cobs is an agricultural byproduct containing polysaccharide composed of cellulose, hemicelluloses and lignin. Hemicelluloses has a hydroxyl and carbonyl functional groups which can be used as chelating agent for metal ions. The purpose of this study was to isolate and evaluate corncobs hemicelluloses as a chelating agent toward lead ion. Graphite furnace spectrophotometry at 283.3 nm was used to determine the residual lead ion in solution. The research's result showed that the highest yield of hemicelluloses (12.04 %) was obtained from delignication with 0,03 M NaOH in 60 % ethanol and 3 % H2O2, hemicelluloses isolation with 500 ml of 0.2 M NaOH, and precipitation with 1:4 ratio of 10 % acetic acid in 95 % ethanol. The 300 mg corn cobs hemicelluloses has chelating effect for 40 mg lead solution at (39.52±0.1350) mg or 98.80 %, that the corn cobs hemicelluloses can be used as a chelating agent for lead. (author)

  11. CoMo/ZrO2 Hydrodesulfurization Catalysts Prepared by Chelating Agent Assisted Spreading

    Kaluža, L. (Luděk); Gulková, D. (Daniela); Vít, Z. (Zdeněk); Zdražil, M. (Miroslav)

    2012-01-01

    The novel Mo/ZrO2 and CoMo/ZrO2 catalysts were prepared by impregnation of the monoclinic ZrO2 by the chelating agent nitrilotriacetic acid (NTA) assisted spreading of MoO3 with CoCO3 xH2O and compared with samples prepared conventionally. The application of NTA during the catalysts preparation systematically increased the activity in benzothiophene HDS by the factor 1.2–1.7.

  12. High-performance lithium-rich layered oxide materials: Effects of chelating agents on microstructure and electrochemical properties

    The mechanisms and effects of three typical chelating agents, namely glucose, citric acid and sucrose on the sol-gel synthesis process, electrochemical degradation and structural evolution of 0.5Li2MnO3·0.5LiNi0.5Co0.2Mn0.3O2 (LLMO) materials are systematically compared for the first time. X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and high-resolution transmission electron microscopy analysis indicate that the sample synthesized from sucrose owns well structure, homogenous distribution, low Ni3+ concentration and good surface structural stability during cycling, respectively. Electrochemical tests further prove that the LLMO material obtained from sucrose maintains 258.4 mAh g−1 with 94.8% capacity retention after 100 cycles at 0.2 C. The superior electrochemical performance can be ascribed to the exceptional complexing mechanism of sucrose, compared to those of the glucose and citric acid. Namely, one mole sucrose can be hydrolyzed into two different monosaccharides and further chelates three M (Li, Ni, Co and Mn) ions to form a more uniform ion-chelated matrix during sol-gel process. This discovery is an important step towards understanding the selection criterion of chelating agents for sol-gel method, that chelating agent with excellent complexing capability is beneficial to the distribution, structural stability and electrochemical properties of advanced lithium-rich layered materials

  13. Separation and recovery of uranium ore by chlorinating, chelate resin and molten salt treatment

    Taki, Tomohiro [Japan Nuclear Cycle Development Inst., Kamisaibara, Okayama (Japan). Ningyo Toge Environmental Engineering Center

    2000-12-01

    Three fundamental researches of separation and recovery of uranium from uranium ore are reported in this paper. Three methods used the chloride pyrometallurgy, sodium containing molten salts and chelate resin. When uranium ore is mixed with activated carbon and reacted for one hour under the mixed gas of chlorine and oxygen at 950 C, more than 90% uranium volatilized and vaporization of aluminum, silicone and phosphorus were controlled. The best activated carbon was brown coal because it was able to control the large range of oxygen concentration. By blowing oxygen into the molten sodium hydroxide, the elution rate of uranium attained to about 95% and a few percent of uranium was remained in the residue. On the uranium ore of unconformity-related uranium deposits, a separation method of uranium, molybdenum, nickel and phosphorus from the sulfuric acid elusion solution with U, Ni, As, Mo, Fe and Al was developed. Methylene phosphonic acid type chelate resin (RCSP) adsorbed Mo and U, and then 100 % Mo was eluted by sodium acetate solution and about 100% U by sodium carbonate solution. Ni and As in the passing solution were recovered by imino-diacetic acid type chelate resin and iron hydroxide, respectively. (S.Y.)

  14. Separation and recovery of uranium ore by chlorinating, chelate resin and molten salt treatment

    Three fundamental researches of separation and recovery of uranium from uranium ore are reported in this paper. Three methods used the chloride pyrometallurgy, sodium containing molten salts and chelate resin. When uranium ore is mixed with activated carbon and reacted for one hour under the mixed gas of chlorine and oxygen at 950 C, more than 90% uranium volatilized and vaporization of aluminum, silicone and phosphorus were controlled. The best activated carbon was brown coal because it was able to control the large range of oxygen concentration. By blowing oxygen into the molten sodium hydroxide, the elution rate of uranium attained to about 95% and a few percent of uranium was remained in the residue. On the uranium ore of unconformity-related uranium deposits, a separation method of uranium, molybdenum, nickel and phosphorus from the sulfuric acid elusion solution with U, Ni, As, Mo, Fe and Al was developed. Methylene phosphonic acid type chelate resin (RCSP) adsorbed Mo and U, and then 100 % Mo was eluted by sodium acetate solution and about 100% U by sodium carbonate solution. Ni and As in the passing solution were recovered by imino-diacetic acid type chelate resin and iron hydroxide, respectively. (S.Y.)

  15. Effects of Zinc Chelators on Aflatoxin Production in Aspergillus parasiticus

    Wee, Josephine; Day, Devin M.; Linz, John E.

    2016-01-01

    Zinc concentrations strongly influence aflatoxin accumulation in laboratory media and in food and feed crops. The presence of zinc stimulates aflatoxin production, and the absence of zinc impedes toxin production. Initial studies that suggested a link between zinc and aflatoxin biosynthesis were presented in the 1970s. In the present study, we utilized two zinc chelators, N,N,N′,N′-tetrakis (2-pyridylmethyl) ethane-1,2-diamine (TPEN) and 2,3-dimercapto-1-propanesulfonic acid (DMPS) to explore the effect of zinc limitation on aflatoxin synthesis in Aspergillus parasiticus. TPEN but not DMPS decreased aflatoxin biosynthesis up to six-fold depending on whether A. parasiticus was grown on rich or minimal medium. Although we observed significant inhibition of aflatoxin production by TPEN, no detectable changes were observed in expression levels of the aflatoxin pathway gene ver-1 and the zinc binuclear cluster transcription factor, AflR. Treatment of growing A. parasiticus solid culture with a fluorescent zinc probe demonstrated an increase in intracellular zinc levels assessed by increases in fluorescent intensity of cultures treated with TPEN compared to controls. These data suggest that TPEN binds to cytoplasmic zinc therefore limiting fungal access to zinc. To investigate the efficacy of TPEN on food and feed crops, we found that TPEN effectively decreases aflatoxin accumulation on peanut medium but not in a sunflower seeds-derived medium. From an application perspective, these data provide the basis for biological differences that exist in the efficacy of different zinc chelators in various food and feed crops frequently contaminated by aflatoxin. PMID:27271668

  16. Effects of Zinc Chelators on Aflatoxin Production in Aspergillus parasiticus.

    Wee, Josephine; Day, Devin M; Linz, John E

    2016-01-01

    Zinc concentrations strongly influence aflatoxin accumulation in laboratory media and in food and feed crops. The presence of zinc stimulates aflatoxin production, and the absence of zinc impedes toxin production. Initial studies that suggested a link between zinc and aflatoxin biosynthesis were presented in the 1970s. In the present study, we utilized two zinc chelators, N,N,N',N'-tetrakis (2-pyridylmethyl) ethane-1,2-diamine (TPEN) and 2,3-dimercapto-1-propanesulfonic acid (DMPS) to explore the effect of zinc limitation on aflatoxin synthesis in Aspergillus parasiticus. TPEN but not DMPS decreased aflatoxin biosynthesis up to six-fold depending on whether A. parasiticus was grown on rich or minimal medium. Although we observed significant inhibition of aflatoxin production by TPEN, no detectable changes were observed in expression levels of the aflatoxin pathway gene ver-1 and the zinc binuclear cluster transcription factor, AflR. Treatment of growing A. parasiticus solid culture with a fluorescent zinc probe demonstrated an increase in intracellular zinc levels assessed by increases in fluorescent intensity of cultures treated with TPEN compared to controls. These data suggest that TPEN binds to cytoplasmic zinc therefore limiting fungal access to zinc. To investigate the efficacy of TPEN on food and feed crops, we found that TPEN effectively decreases aflatoxin accumulation on peanut medium but not in a sunflower seeds-derived medium. From an application perspective, these data provide the basis for biological differences that exist in the efficacy of different zinc chelators in various food and feed crops frequently contaminated by aflatoxin. PMID:27271668

  17. Modern problems of chelate water conditions for TPPs and NPPs

    Review of investigations devoted to the application of chelate water conditions for TPPs and NPPs is given. Chelates (mainly EDTA and its salts) are used for increasing corrosion resistance of steels, operation and pre-start-up chemical purifications, correction of water conditions and coolant circuit purification under operation (without shutdown). It is stressed that under certain conditions the optimal continuous chelate water conditions are possible under water conditions are possible under which deposits are not produced

  18. REGIONAL SIDEROSIS: A NEW CHALLENGE FOR IRON CHELATION THERAPY

    ZviIoavCabantchik; ArnoldMunnich; MoussaB.Youdim; DavidDevos

    2013-01-01

    The traditional role of iron chelation therapy has been to reduce body iron burden via chelation of excess metal from organs and fluids and its excretion via biliary-fecal and/or urinary routes. In their present use for hemosiderosis, chelation regimens might not be suitable for treating disorders of iron maldistribution, as those are characterized by toxic islands of siderosis appearing in a background of normal or subnormal iron levels (e.g. sideroblastic anemias, neuro- and cardio-siderosi...

  19. Trypanotoxic activity of thiosemicarbazone iron chelators

    Ellis, Samuel; Sexton, Darren; Steverding, Dietmar

    2015-01-01

    Only a few drugs are available for treating sleeping sickness and nagana disease; parasitic infections caused by protozoans of the genus Trypanosoma in sub-Saharan Africa. There is an urgent need for the development of new medicines for chemotherapy of these devastating diseases. In this study, three newly designed thiosemicarbazone iron chelators, TSC24, Dp44mT and 3-AP, were tested for in vitro activity against bloodstream forms of T. brucei and human leukaemia HL-60 cells. In addition to t...

  20. Novel Terbium Chelate Doped Fluorescent Silica Nanoparticles

    Ning Qiaoyu; Meng Jianxin; Wang Haiming; Liu Yingliang; Man Shiqing

    2006-01-01

    Novel terbium chelate doped silica fluorescent nanoparticles were prepared and characterized.The preparation was carried out in water-in-oil (W/O) microemulsion containing monomer precursor (pAB-DTPAA-APTEOS), Triton X-100, n-hexanol, and cyclohexane by controlling copolymerization of tetraethyl orthosilicate and 3-aminopropyl-triethyloxysilane.The nanoparticles are spherical and uniform in size, about 30 nm in diameter, strongly fluorescent, and highly stable.The amino groups directly introduced to the surface of the nanoparticles using APTEOS during preparation made the surface modification and bioconjugation of the nanoparticles easier.The nanoparticles are expected as an efficient time-resolved luminescence biological label.

  1. Towards the Rational Design of MRI Contrast Agents: δ-Substitution of Lanthanide(III) NB-DOTA-Tetraamide Chelates Influences but Does Not Control Coordination Geometry**

    Carney, Christiane E.; Tran, Anh D.; Jing WANG; Schabel, Matthias C.; Sherry, A. Dean; Woods, Mark

    2011-01-01

    LnDOTA-tetraamide chelates (DOTA=1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) have received considerable recent attention as a result of their potential to act as PARACEST contrast agents for magnetic resonance imaging (MRI). Although PARACEST agents afford several advantages over conventional contrast agents they suffer from substantially higher detection limits; thus, improving the effectiveness of LnDOTA-tetraamide chelates is an important goal. In this study we investigate th...

  2. Composition and stability of Nb(V), Zr(IV), Y(III) and La(III) chelates with 7-nitroso-8-quinolinone-5-sulphonate

    New Nb(V), Zr(IV), Y(III) and La(III) chelates obtained from disodium salt of 7-nitroso-8-quinolinole-5-sulphonic acid were studied using spectrophotometric, conductimetric and potentiometric methods. The solid chelates were synthesized and their ir spectra and elemental analysis were discussed. The ligand is bonded to the metal ion through the oxygens of nitroso and hydroxy groups. The apparent stability constants of the complexes formed in solution were also determined spectrophotometrically and potentiometrically

  3. Plutonium-237: comparative uptake in chelated and non-chelated form by channel catfish (Ictalurus punctatus)

    Chelation can either enhance or reduce the uptake of ingested plutonium relative to PuOH (monomer) in channel catfish. Reduced uptake of 237Pu-fulvate is due either to the molecular weight of the complex or its stability in metabolic systems. Increased uptake of 237Pu-citrate is attributable to instability of the complex in metabolic systems. (author)

  4. Metal regeneration of iron chelates in nitric oxide scrubbing

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

    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 and 90 C to reduce NO present, produce ammonia or an ammonium ion, and produce free iron (II) (CHELATE) at a pH of between about 3 and 8. The process is useful to remove NO from flue gas and reduce pollution. 34 figs.

  5. Mild formation of cyclic carbonates using Zn(II) complexes based on N2S2-chelating ligands

    D. Anselmo; V. Bocokic; A. Decortes; E.C. Escudero-Adan; J. Benet-Buchholz; J.N.H. Reek; A.W. Kleij

    2012-01-01

    We have prepared a series of Zn(II) complexes (1-3) based on a versatile N2S2-chelating ligand abbreviated as btsc [btsc = bis-(thiosemicarbazonato)] derived from simple and accessible building blocks. These complexes comprise a Lewis acidic Zn(II) center useful for substrate activation, and we have

  6. COMPARATIVE STUDY OF CHELATION VALUE OF SEVENTEEN PERCENT SELF DEVELOPED AND COMMERCIALLY AVAILABLE ROOT CANAL LUBRICANTS

    Ingale Satish Dinkarrao

    2013-06-01

    Full Text Available The main objective of this study is to compare chelation values of 17% self developed & commercially available root canal Lubricants or dental chelating gels as well as to see whether their performance depends on the chelation value or not. The Chelating agent bounds Ca2+ ions of the smear layer & the extent of chelate formation between chelating agent and metal ion is nothing but Chelation Value. Sodium carbonate indicator method is used for determinations of chelation value. Commercially available gel incorporated in this study was File Rite which has little bit higher chelation value. Self developed chelating gel or root canal lubricants have comparatively lower chelation value. Root canal lubricants having higher chelation value should perform better in shaping & cleaning of root canal better. However because of slight difference in chelation value of self developed & commercially available gel, no significant difference was found out as root canal lubricants, when applied in root canal for 5 minutes.

  7. Chemical treatment of chelated metal finishing wastes.

    McFarland, Michael J; Glarborg, Christen; Ross, Mark A

    2012-12-01

    This study evaluated two chemical approaches for treatment of commingled cadmium-cyanide (Cd-CN) and zinc-nickel (Zn-Ni) wastewaters. The first approach, which involved application of sodium hypochlorite (NaOCl), focused on elimination of chelating substances. The second approach evaluated the use of sodium dimethyldithiocarbamate (DMDTC) to specifically target and precipitate regulated heavy metals. Results demonstrated that by maintaining a pH of 10.0 and an oxidation-reduction potential (ORP) value of +600 mV, NaOCl treatment was effective in eliminating all chelating substances. Cadmium, chromium, nickel, and zinc solution concentrations were reduced from 0.27, 4.44, 0.06, and 0.10 ppm to 0.16, 0.17, 0.03, and 0.06 ppm, respectively. Similarly, a 1% DMDTC solution reduced these same metal concentrations in commingled wastewater to 0.009, 1.142, 0.036, and 0.320 ppm. Increasing the DMDTC concentration to 2% improved the removal of all regulated heavy metals except zinc, the removal of which at high pH values is limited by its amphotericity. PMID:23342939

  8. Decorporation of inhaled actinides by chelation therapy

    This article describes recent work in NRPB laboratories that has identified some of the factors influencing the behaviour of plutonium, americium and curium compounds in the body after inhalation, together with a number of experimental approaches that are being developed to optimise their treatment with DTPA. It is concluded that the most effective treatment has yet to be developed, but progress must depend on a better understanding of the factors governing the transport of actinides in the body. It cannot be assumed that because the inhaled material is readily translocated to blood, that treatment regimens with Ca-DTPA based solely on previous understanding of the metabolic fate of soluble actinide complexes will be successful. In fact, depending on the nature of the material involved in the accident, inhalation alone or combined with prolonged infusion of DTPA may be more effective than the periodic intravenous injections of the chelating agent alone. For poorly transportable materials such as insoluble plutonium-239 dioxide, chelation treatment remains essentially ineffective. (U.K.)

  9. Assessment of the Efficacy of Chelate-Assisted Phytoextraction of Lead by Coffeeweed (Sesbania exaltata Raf.

    Gloria Miller

    2008-12-01

    Full Text Available Lead (Pb, depending upon the reactant surface, pH, redox potential and other factors can bind tightly to the soil with a retention time of many centuries. Soil-metal interactions by sorption, precipitation and complexation processes, and differences between plant species in metal uptake efficiency, transport, and susceptibility make a general prediction of soil metal bioavailability and risks of plant metal toxicity difficult. Moreover, the tight binding characteristic of Pb to soils and plant materials make a significant portion of Pb unavailable for uptake by plants. This experiment was conducted to determine whether the addition of ethylenediaminetetraacetic acid (EDTA, ethylene glycol tetraacetic acid (EGTA, or acetic acid (HAc can enhance the phytoextraction of Pb by making the Pb soluble and more bioavailable for uptake by coffeeweed (Sesbania exaltata Raf.. Also we wanted to assess the efficacy of chelates in facilitating translocation of the metal into the above-ground biomass of this plant. To test the effect of chelates on Pb solubility, 2 g of Pb-spiked soil (1000 mg Pb/kg dry soil were added to each 15 mL centrifuge tube. Chelates (EDTA, EGTA, HAc in a 1:1 ratio with the metal, or distilled deionized water were then added. Samples were shaken on a platform shaker then centrifuged at the end of several time periods. Supernatants were filtered with a 0.45 μm filter and quantified by inductively coupled plasma-optical emission spectrometry (ICP-OES to determine soluble Pb concentrations. Results revealed that EDTA was the most effective in bringing Pb into solution, and that maximum solubility was reached 6 days after chelate amendment. Additionally, a greenhouse experiment was conducted by planting Sesbania seeds in plastic tubes containing top soil and peat (2:1, v:v spiked with various levels (0, 1000, 2000 mg Pb/kg dry soil of lead nitrate. At six weeks after emergence, aqueous solutions of EDTA and/or HAc (in a 1:1 ratio

  10. Molecular Docking Assessment of Efficacy of Different Clinically Used Arsenic Chelator Drugs

    Durjoy Majumder

    2013-01-01

    Full Text Available Arsenic contamination of ground water has become a global problem affecting specially, south-east Asian countries like Bangladesh and eastern parts of India. It also affects South America and some parts of the US. Different organs of the physiological system are affected due to contamination of inorganic arsenic in water. Animal studies with different chelators are not very conclusive as far as the multi/differential organ effect(s of arsenic is concerned. Our docking study establishes the molecular rationale of blood test for early detection of arsenic toxicity; as arsenic has a high affinity to albumin, a plasma protein and actin, a structural protein of all cells including Red Blood Cells. This study also shows that there is a little possibility of male reproductive organs toxicity by different forms of inorganic arsenic; however, female reproductive system is very much susceptible to sodium-arsenite. Through comparative analysis regarding the chelating effectiveness among the available arsenic chelator drugs, meso-2,3 dimercaptosuccinic acid (DMSA and in some cases lipoic acid is the most preferred choice of drug for removing of arsenic deposits. This computational method actually reinforces the clinical finding regarding DMSA as the most preferred drug in removal of arsenic deposits from majority of the human tissues.