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

PubMed

Mosayebnia, Mona; Shafiee-Ardestani, Mehdi; Pasalar, Parvin; Mashayekhi, Mojgan; Amanlou, Massoud

2014-01-01

To find out whether DTPA-DG complex can enhance clearance of intracellular free iron. 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. 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. 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.

[Enhanced phytoextraction of heavy metal contaminated soil by chelating agents and auxin indole-3-acetic acid].

PubMed

Zhou, Jian-min; Dang, Zhi; Chen, Neng-chang; Xu, Sheng-guang; Xie, Zhi-yi

2007-09-01

The environmental risk of chelating agents such as EDTA application to the heavy metals polluted soils and the stress on plant roots due to the abrupt increase metals concentration limit the wide commercial use of chelate-induced phytoextraction. Chelating agent ethylenediaminetetraacetic acid (EDTA) and nitrilotriacetic acid (NTA) and auxin indole-3-acetic acid (IAA) were used for enhancing heavy metals uptake from soils by Zea mays L. (corn) in pot experiments. The metals content in plant tissues was quantified using an inductively coupled plasma mass spectrometer (ICP-MS). The results showed that the combination of IAA and EDTA increased the biomass by about 40.0% and the contents of Cu, Zn, Cd and Pb in corn shoots by 27.0%, 26.8%, 27.5% and 32.8% respectively, as compared to those in EDTA treatment. While NTA&IAA treatment increased the biomass by about 29.9% and the contents of Cu, Zn, Cd and Pb in corn shoots by 31.8%, 27.6%, 17.0% and 26.9% respectively, as compared to those in NTA treatment. These results indicated that corn growth was promoted, and the biomass and the accumulation of heavy metals in plant shoots were increased significantly with the addition of IAA, which probably helps to change the cell membrane properties and the biomass distribution, resulting in the alleviation of the phytotoxicity of metals and the chelating agents.

Chelate assisted phytoextraction of heavy metals from soil. Effect, mechanism, toxicity, and fate of chelating agents.

PubMed

Evangelou, Michael W H; Ebel, Mathias; Schaeffer, Andreas

2007-06-01

The low-cost, plant-based phytoextraction technique has often been described as a promising technique to remediate heavy metal contaminated agricultural land. The application of chelating agents has shown positive effects in increasing the solubility of heavy metals in soil and therefore in enhancing phytoextraction. This paper gives an overview of the chelating agents applied in recent studies. Various synthetic aminopolycarboxylic acids, such as ethylene diamine tetraacetic acid, and natural ones such as, ethylene diamine disuccinate and nitrilotriacetic acid, are described. Additionally, results of the application of natural low molecular weight organic acids, such as citric and tartaric acid are given. The effectiveness of these different chelating agents varies according to the plant and the heavy metals used. Furthermore, a focus is laid on the chelating agents fate after application and on its toxicity to plants and soil microorganisms, as well as it degradation. The rate of degradation is of great importance for the future of chelate assisted phytoextraction as it has a direct impact on the leaching probability. An effective prevention of leaching will be crucial for the acceptance and the economic breakthrough of enhanced phytoextraction, but a satisfactory solution to this key issue has so far not been found. Possibly further experiments in the field of enhanced phytoextraction will be able to solve this major problem, but over decades various greenhouse experiments and recently field experiments have resulted in different observations. Therefore, it is questionable if further research in this direction will lead to a promising solution. Phytoextraction has possibly reached a turning point in which it should distance itself from chelate assisted phytoextraction and focus on alternative options.

Wet spinning of solid polyamic acid fibers

NASA Technical Reports Server (NTRS)

Dorogy, William E., Jr. (Inventor); Saintclair, Anne K. (Inventor)

1989-01-01

The invention is a process for the production of solid aromatic polyamic acid and polyimide fibers from a wet gel or coagulation bath wet gel using N,N-dimethylacetamide (DMAc) solution of the polyamic acid derived from aromatic dianhydrides such as 3,3',4,4'-benzo phenone tetracarboxylic dianhydride (BTDA) and aromatic diamines such as 4,4'oxydianiline (4,4'-ODA). By utilizing the interrelationship between coagulation medium and concentration, resin inherent viscosity, resin percent solids, filament diameter, and fiber void content, it is possible to make improved polyamic acid fibers. Solid polyimide fibers, obtained by the thermal cyclization of the polyamic acid precursor, have increased tensile properties compared to fibers containing macropores from the same resin system.

Wet spinning of solid polyamic acid fibers

NASA Technical Reports Server (NTRS)

Dorogy, William E., Jr. (Inventor); St.clair, Anne K. (Inventor)

1991-01-01

The invention is a process for the production of solid aromatic polyamic acid and polyimide fibers from a wet gel or coagulation bath wet gel using N,N-dimethylacetamide (DMAc) solutions of the polyamic acid derived from aromatic dianhydrides such as 3,3',4,4' benzophenonetetra carboxylic dianhydride (BTDA) and aromatic diamines such as 4,4'-oxydianiline (4,4'-ODA). By utilizing the relationship among coagulation medium and concentration, resin inherent viscosity, resin percent solids, filament diameter, and fiber void content, it is possible to make improved polyamic acid fibers. Solid polyimide fibers, obtained by the thermal cyclization of the polyamic acid precursor, have increased tensile properties compared to fibers containing macropores from the same resin system.

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

NASA Astrophysics Data System (ADS)

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

2008-07-01

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

Chelation in Metal Intoxication

PubMed Central

Flora, Swaran J.S.; Pachauri, Vidhu

2010-01-01

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

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.

PubMed

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

Flame and acid resistant polymide fibers

NASA Technical Reports Server (NTRS)

Stringham, R. S.; Toy, M. S.

1977-01-01

Economical process improves flame resistance and resistance to acids of polyamide fibers, without modifying colors of mechanical properties. Process improves general safety of garments and other items made from polyamide fibers and makes them suitable for applications requiring exposure to oxygen-rich atmosphere or corrosive acids. Halo-olefins are added to surface of fibers by photoadditon in sealed chamber. Process could be used with films and other forms of polyamide.

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

NASA Astrophysics Data System (ADS)

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.

Succinic acid production from acid hydrolysate of corn fiber by Actinobacillus succinogenes.

PubMed

Chen, Kequan; Jiang, Min; Wei, Ping; Yao, Jiaming; Wu, Hao

2010-01-01

Dilute acid hydrolysate of corn fiber was used as carbon source for the production of succinic acid by Actinobacillus succinogenes NJ113. The optimized hydrolysis conditions were obtained by orthogonal experiments. When corn fiber particles were of 20 mesh in size and treated with 1.0% sulfuric acid at 121 degrees C for 2 h, the total sugar yield could reach 63.3%. It was found that CaCO(3) neutralization combined with activated carbon adsorption was an effective method to remove fermentation inhibitors especially furfural that presented in the acid hydrolysate of corn fiber. Only 5.2% of the total sugar was lost, while 91.9% of furfural was removed. The yield of succinic acid was higher than 72.0% with the detoxified corn fiber hydrolysate as the carbon source in anaerobic bottles or 7.5 L fermentor cultures. It was proved that the corn fiber hydrolysate could be an alternative to glucose for the production of succinic acid by A. succinogenes NJ113.

Chelation in root canal therapy reconsidered.

PubMed

Zehnder, Matthias; Schmidlin, Patrick; Sener, Beatrice; Waltimo, Tuomas

2005-11-01

The aim of this study was to assess interactions of EDTA and citric acid (CA) with sodium hypochlorite (NaOCl), the indispensable endodontic irrigant. Other chelators were simultaneously evaluated as possible alternatives: sodium triphosphate (STP), amino tris methylenephosphonic acid (ATMA), and 1- hydroxyethylidene-1, 1-bisphosphonate (HEBP). Available chlorine was titrated in chelator-NaOCl solutions. All chelators other than HEBP and STP caused an almost complete, immediate loss of available chlorine in solution. Atomic absorbtion spectrometry and SEM evaluation of root canal walls of instrumented teeth indicated that NaOCl had no negative effect on calcium-complexing ability of chelators. STP was too weak a complexing agent to warrant further studies. Finally, CA-, EDTA-, and HEBP-NaOCl mixtures were evaluated for their antimicrobial capacity. Again, EDTA and CA negatively interfered with NaOCl, while HEBP did not.

Comparison of natural organic acids and synthetic chelates at enhancing phytoextraction of metals from a multi-metal contaminated soil.

PubMed

do Nascimento, Clístenes Williams A; Amarasiriwardena, Dula; Xing, Baoshan

2006-03-01

Chemically assisted phytoremediation has been developing to induce accumulation of metals by high biomass plants. Synthetic chelates have shown high effectiveness to reach such a goal, but they pose serious drawbacks in field application due to the excessive amount of metals solubilized. We compared the performance of synthetic chelates with naturally occurring low molecular weight organic acids (LMWOA) in enhancing phytoextraction of metals by Indian mustard (Brassica juncea) from multi-metal contaminated soils. Gallic and citric acids were able to induce removal of Cd, Zn, Cu, and Ni from soil without increasing the leaching risk. Net removal of these metals caused by LMWOA can be as much as synthetic chelates. A major reason for this is the lower phytotoxicity of LMWOA. Furthermore, supplying appropriate mineral nutrients increased biomass and metal removal.

Chelating effect of citric acid is negligible for development of enamel erosions.

PubMed

Azadi-Schossig, Parastu; Becker, Klaus; Attin, Thomas

2016-09-01

Citric acid (CA) is a component in beverages responsible for dental erosion. The aim of this study was to examine the influence of CA with different pH, titratable acid and buffer capacity (ß), and the impact of the chelating effect of CA on development of enamel erosions. In a superfusion model, hydroxy apatite (HAp) dissolution of bovine enamel was measured in four experiments (EXP 1-4) with 27 experimental groups (n = 8 per group). The samples were superfused with different CA variations and respective controls. EXP-1: Dilution series of HCl (pH 2.15-3.02). EXP-2: Dilution series of natural CA (56-1.75 mmol l(-1); pH 2.15-3.02). EXP-3: CA solutions (56 and 14 mmol l(-1), ß: 39.7 and 10.2 mmol l(-1) pH(-1), respectively) with different titratable acidity at equal pH values. EXP-4: CA concentrations (56-1.75 mmol l(-1)) neutralized to pH 7. CA led to higher HAp-dissolution than HCl. With higher pH, the difference in HAp-dissolution rate between the two acids became increasingly smaller. At equal pH, HAp-dissolution was higher for the CA with the higher amount of titratable acid. However, no clear correlation between erosion and titratable acid or ß could be found. Only minimal amounts of HAp were dissolved by neutralized CA compared to CA with natural pH. Under the chosen conditions chelating effects of CA do not have a relevant influence of HAp-dissolution of enamel. Moreover, amount of HAp-dissolution by CA is not attributed to a single factor alone. The interplay between the different parameters of CA seems to be responsible for its erosive potential. The erosive potential of solutions containing citric acid with unknown concentrations could not be predicted using a single parameter alone, and should at best determined in experimental set-ups.

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

PubMed

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. Copyright © 2015 Elsevier B.V. All rights reserved.

Metal ion promoted hydrogels for bovine serum albumin adsorption: Cu(II) and Co(II) chelated poly[(N-vinylimidazole)-maleic acid].

PubMed

Pekel, Nursel; Salih, Bekir; Güven, Olgun

2005-05-10

Poly[(N-vinylimidazole)-maleic acid] (poly(VIm-MA)), copolymeric hydrogels were prepared by gamma-irradiating ternary mixtures of N-vinylimidazole-maleic acid-water in a (60)Co-gamma source. Cu(II) and Co(II) ions were chelated within the gels at pH=5.0. The maximum adsorption capacity of the gels were 3.71 mmol/g dry gel for Cu(II) and 1.25 mmol/g dry gel for Co(II) at pH=5.0. The swelling ratios of the gels were 1200% for poly(VIm-MA), 60 and 45% for Cu(II) and Co(II)-chelated poly(VIm-MA) gels at pH=5.0 in acetate buffer solution. These affinity gels with different swelling ratios for plain poly(VIm-MA), Cu(II)-, and Co(II)-chelated poly(VIm-MA), in acetate and phosphate buffers were used in the bovine serum albumin (BSA) adsorption/desorption studies in batch reactor. The maximum BSA adsorption capacities of the gels were 0.38 g/g dry gel for plain, 0.88 g/g dry gel for Cu(II)-chelated poly(VIm-MA) and 1.05 g/g dry gel for Co(II)-chelated poly(VIm-MA) gels. Adsorption capacity of BSA by the gels was reduced dramatically by increasing the ionic strength adjusted with NaCl. More than 95% of BSA were desorbed in 10 h in desorption medium containing 0.1M of EDTA for metal ion-chelated gels at pH=4.7.

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

PubMed

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. Copyright © 2015 Elsevier Ltd. All rights reserved.

Labeling of monoclonal antibodies with a 67Ga-phenolic aminocarboxylic acid chelate. Part I. Chemistry and labeling technique.

PubMed

Schuhmacher, J; Matys, R; Hauser, H; Maier-Borst, W; Matzku, S

1986-01-01

As a chelating agent for labeling antibodies (Abs) with metallic radionuclides, a propionic acid substituted ethylenediamine N,N'-di-[(o-hydroxyphenyl) acetic acid] (P-EDDHA), which tightly complexes 67Ga, was synthesized. The 67Ga-P-EDDHA chelate was coupled in aqueous solution to IgG at a molar ratio of 1:1 via carbodiimide. The average coupling yield was 15%. A specific activity of 4 mCi/mg IgG could be obtained with commercially supplied 67Ga. In vitro stability was evaluated in human serum at 37 degrees C and showed a half-life of about 120 h for the release of 67Ga from the labeled Ab during the initial phase of incubation. This in vitro halflife is similar to that measured for 111In-DTPA labeled Abs. Because of the high stability of the 67Ga-P-EDDHA chelate, the in vivo formation of radioactive labeled transferrin by transchelation, as described for 111In-DTPA labeled Abs, should, however, be reduced by this labeling technique.

Antioxidant and chelating capacity of Maillard reaction products in amino acid-sugar model systems: applications for food processing.

PubMed

Mondaca-Navarro, Blanca A; Ávila-Villa, Luz A; González-Córdova, Aarón F; López-Cervantes, Jaime; Sánchez-Machado, Dalia I; Campas-Baypoli, Olga N; Rodríguez-Ramírez, Roberto

2017-08-01

Maillard reaction products (MRP) have gained increasing interest owing to their both positive and negative effects on human health. Aqueous amino acid-sugar model systems were studied in order to evaluate the antioxidant and chelating activity of MRP under conditions similar to those of food processing. Amino acids (cysteine, glycine, isoleucine and lysine) combined with different sugars (fructose or glucose) were heated to 100 and 130 °C for 30, 60 and 90 min. Antioxidant capacity was evaluated via ABTS and DPPH free radical scavenging assays, in addition to Fe 2+ and Cu 2+ ion chelating capacity. In the ABTS assay, the cysteine-fructose model system presented the highest antioxidant activity at 7.05 µmol mL -1 (130 °C, 60 min), expressed in Trolox equivalents. In the DPPH assay, the cysteine-glucose system presented the highest antioxidant activity at 3.79 µmol mL -1 (100 °C, 90 min). The maximum rate of chelation of Fe 2+ and Cu 2+ was 96.31 and 59.44% respectively in the lysine-fructose and cysteine-glucose systems (100 °C, 30 min). The model systems presented antioxidant and chelating activity under the analyzed temperatures and heating times, which are similar to the processing conditions of some foods. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Chromatographic determination of Fe chelated by ethylenediamine-N-(o-hydroxyphenylacetic)-N'-(p-hydroxyphenylacetic) acid in commercial EDDHA/Fe3+ fertilizers.

PubMed

García-Marco, Sonia; Torreblanca, Ana; Lucena, Juan J

2006-02-22

EDDHA/Fe3+ chelates are the most common fertilizers used to solve Fe chlorosis in established crops. Commercial products contain two regioisomers, ethylenediamine-N,N'-bis(o-hydroxyphenylacetic) acid (o,o-EDDHA)/Fe3+ and ethylenediamine-N-(o-hydroxyphenylacetic)-N'-(p-hydroxyphenylacetic) acid (o,p-EDDHA)/Fe3+. Although several chromatographic methods exist for the determination of Fe3+ chelated by the o,o-EDDHA isomer, no method has been described for the quantification of Fe3+ chelated by o,p-EDDHA. In this work, factors that affect the behavior of o,p-EDDHA/Fe3+ in ion pair chromatography are reviewed: pH, ion pair reagent, and organic modifier. The best chromatographic performance was obtained with an aqueous mobile phase at pH 6.0 containing 35% acetonitrile and 5 mM tetrabutylammonium hydroxide under isocratic elution conditions. This method was applied to the quantification of commercial samples.

Extraction of metals using supercritical fluid and chelate forming legand

DOEpatents

Wai, Chien M.; Laintz, Kenneth E.

1998-01-01

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 .beta.-diketone. In especially preferred embodiments the extraction solvent is supercritical carbon dioxide, and the chelating agent comprises a fluorinated .beta.-diketone and a trialkyl phosphate, or a fluorinated .beta.-diketone and a trialkylphosphine oxide. Although a trialkyl phosphate can extract lanthanides and actinides from acidic solutions, a binary mixture comprising a fluorinated .beta.-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.

Extraction of metals using supercritical fluid and chelate forming ligand

DOEpatents

Wai, C.M.; Laintz, K.E.

1998-03-24

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 {beta}-diketone. In especially preferred embodiments the extraction solvent is supercritical carbon dioxide, and the chelating agent comprises a fluorinated {beta}-diketone and a trialkyl phosphate, or a fluorinated {beta}-diketone and a trialkylphosphine oxide. Although a trialkyl phosphate can extract lanthanides and actinides from acidic solutions, a binary mixture comprising a fluorinated {beta}-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.

Potassium fulvate-modified graft copolymer of acrylic acid onto cellulose as efficient chelating polymeric sorbent.

PubMed

Mohamed, Magdy F; Essawy, Hisham A; Ammar, Nabila S; Ibrahim, Hanan S

2017-01-01

Acrylic acid (AA) was graft copolymerized from cellulose (Cell) in presence of potassium fulvate (KF) in order to enhance the chemical activity of the resulting chelating polymer and the handling as well. Fourier transform infrared (FTIR) proved that KF was efficiently inserted and became a permanent part of the network structure of the sorbent in parallel during the grafting copolymerization. Scanning electron microscopy (SEM) revealed intact homogeneous structure with uniform surface. This indicates improvement of the handling, however, it was not the case for the graft copolymer of acrylic acid onto cellulose in absence of KF, which is known to be brittle and lacks mechanical integrity. Effective insertion of this co-interpenetrating agent provided more functional groups, such as OH and COOH, which improved the chelating power of the produced sorbent as found for the removal of Cu 2+ ions from its aqueous solutions (the removal efficiency reached ∼98.9%). Different models were used to express the experimental data. The results corroborated conformity of the pseudo-second order kinetic model and Langmuir isotherm model to the sorption process, which translates into dominance of the chemisorption. Regeneration of the chelating polymers under harsh conditions did not affect the efficiency of copper ions uptake up to three successive cycles. A thermodynamic investigation ensured exothermic nature of the adsorption process that became less favourable at higher temperatures. Copyright © 2016 Elsevier B.V. All rights reserved.

Assessment of iron chelates efficiency for photo-Fenton at neutral pH.

PubMed

De Luca, Antonella; Dantas, Renato F; Esplugas, Santiago

2014-09-15

In this study, homogeneous photo-Fenton like at neutral pH was applied to remove sulfamethoxazole from water. The process was performed using different chelating agents in order to solubilize iron in a neutral water solution. The chelating agents tested were: ethylenediaminetetraacetic acid (EDTA); nitrilotriacetic acid (NTA); oxalic acid (OA) and tartaric acid (TA). The iron leaching was monitored over reaction time to evaluate the chelates stability and their resistance to HO· and UV-A radiation. Chelates of EDTA and NTA presented more stability than OA and TA, which also confirmed their higher efficiency. Total Organic Carbon (TOC) analyses were also performed to evaluate the contribution in terms of solution contamination related to the use of chelating agents. The better properties of biodegradability in respect of EDTA combined with better efficiency in terms of microcontaminant removal and the smallest TOC contribution indicate that NTA could represent a useful option to perform photo-Fenton processes at neutral pH. Copyright © 2014 Elsevier Ltd. All rights reserved.

Modeling the effect of succimer (DMSA; dimercaptosuccinic acid) chelation therapy in patients poisoned by lead.

PubMed

van Eijkeren, Jan C H; Olie, J Daniël N; Bradberry, Sally M; Vale, J Allister; de Vries, Irma; Clewell, Harvey J; Meulenbelt, Jan; Hunault, Claudine C

2017-02-01

Kinetic models could assist clinicians potentially in managing cases of lead poisoning. Several models exist that can simulate lead kinetics but none of them can predict the effect of chelation in lead poisoning. Our aim was to devise a model to predict the effect of succimer (dimercaptosuccinic acid; DMSA) chelation therapy on blood lead concentrations. We integrated a two-compartment kinetic succimer model into an existing PBPK lead model and produced a Chelation Lead Therapy (CLT) model. The accuracy of the model's predictions was assessed by simulating clinical observations in patients poisoned by lead and treated with succimer. The CLT model calculates blood lead concentrations as the sum of the background exposure and the acute or chronic lead poisoning. The latter was due either to ingestion of traditional remedies or occupational exposure to lead-polluted ambient air. The exposure duration was known. The blood lead concentrations predicted by the CLT model were compared to the measured blood lead concentrations. Pre-chelation blood lead concentrations ranged between 99 and 150 μg/dL. The model was able to simulate accurately the blood lead concentrations during and after succimer treatment. The pattern of urine lead excretion was successfully predicted in some patients, while poorly predicted in others. Our model is able to predict blood lead concentrations after succimer therapy, at least, in situations where the duration of lead exposure is known.

Inhibitory activity of chelating agent against bacteria associated with poultry processing

USDA-ARS?s Scientific Manuscript database

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

Development of an iron chelating polyethylene film for active packaging applications.

PubMed

Tian, Fang; Decker, Eric A; Goddard, Julie M

2012-02-29

Metal-promoted oxidation reactions are a major cause of food quality deterioration. Active packaging offers novel approaches to controlling such oxidation for the purpose of extending shelf life. Herein, we report modification of the surface of polyethylene (PE) films to possess metal chelating activity. Metal chelating carboxylic acids were introduced to the film surface using cross-linking agents [polyethylenimine (PEI) or ethylenediamine (ED)] to increase the number of available carboxylic acids. ATR-FTIR, contact angle, dye assay, and iron chelating assay were used to characterize changes in surface chemistry after each functionalization step. The chelator poly(acrylic acid) (PAA) was attached to the surface at a density of 9.12 ± 0.71 nmol carboxyl groups/cm², and exhibited an iron chelating activity. The results indicate that PAA-modified PE films might have a higher affinity to Fe³⁺ than Fe²⁺ with the optimum binding pH at 5.0. Such inexpensive active packaging materials are promising in food industry for the preservation of liquid and semiliquid food products and have application in heavy metal chelation therapy for biomedical materials as well.

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

DOEpatents

Wai, Chien M.; Smart, Neil G.; Phelps, Cindy

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.

Improved paramagnetic chelate for molecular imaging with MRI

NASA Astrophysics Data System (ADS)

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

2005-05-01

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

Surface Engineering of PAMAM-SDB Chelating Resin with Diglycolamic Acid (DGA) Functional Group for Efficient Sorption of U(VI) and Th(IV) from Aqueous Medium.

PubMed

Ilaiyaraja, P; Deb, A K Singha; Ponraju, D; Ali, Sk Musharaf; Venkatraman, B

2017-04-15

A novel chelating resin obtained via growth of PAMAM dendron on surface of styrene divinyl benzene resin beads, followed by diglycolamic acid functionalization of the dendrimer terminal. Batch experiments were conducted to study the effects of pH, nitric acid concentration, amount of adsorbent, shaking time, initial metal ion concentration and temperature on U(VI) and Th(IV) adsorption efficiency. Diglycolamic acid terminated PAMAM dendrimer functionalized styrene divinylbenzene chelating resin (DGA-PAMAM-SDB) is found to be an efficient candidate for the removal of U(VI) and Th(IV) ions from aqueous (pH >4) and nitric acid media (>3M). The sorption equilibrium could be reached within 60min, and the experimental data fits with pseudo-second-order model. Langmuir sorption isotherm model correlates well with sorption equilibrium data. The maximum U(VI) and Th(IV) sorption capacity onto DGA-PAMAMG 5 -SDB was estimated to be about 682 and 544.2mgg -1 respectively at 25°C. The interaction of actinides and chelating resin is reversible and hence, the resin can be regenerated and reused. DFT calculation on the interaction of U(VI) and Th(IV) ions with chelating resin validates the experimental findings. Copyright © 2017 Elsevier B.V. All rights reserved.

Synthesis and chemical characterization of the novel agronomically relevant pentadentate chelate 2-(2-((2-hydroxybenzyl)amino)ethylamino)-2-(2-hydroxyphenyl)acetic acid (DCHA).

PubMed

López-Rayo, Sandra; Hernández, Diana; Lucena, Juan J; Escudero, Rosa; Gómez-Gallego, Mar; Sierra, Miguel A

2010-07-14

Iron chelates analogous to o,o-EDDHA/Fe(3+) are the fertilizers chosen to treat iron chlorosis in plants growing on calcareous soil. The isomer o,p-EDDHA/Fe(3+) presents less stability but faster assimilation by the plant than o,o-EDDHA/Fe(3+), because only five coordinating groups are able to complex Fe(3+). The new chelating agent 2-(2-((2-hydroxybenzyl)amino)ethylamino)-2-(2-hydroxyphenyl)acetic acid (DCHA) has been synthesized to obtain an iron fertilizer with intermediate stability between o,o-EDDHA/Fe(3+) and o,p-EDDHA/Fe(3+) and with fast assimilation. Its synthesis has been done starting from phenol, N-acetylethylendiamine, glyoxylic acid, and NaOH in a three-step sequence. The purity of the DCHA chelating agent, its protonation, and Ca(2+), Mg(2+), Fe(3+), and Cu(2+) stability constants, together with its ability to maintain iron in solution in different agronomic conditions, have been determined. The results indicate that the chelate DCHA/Fe(3+) has intermediate stability between those of o,o-EDDHA/Fe(3+) and o,p-EDDHA/Fe(3+) complexes and that it is capable of maintaining the Fe(3+) in agronomic conditions. This new chelating agent may be effective in correcting iron chlorosis in plants.

Combined NO/sub x//SO/sub 2/ removal from flue gas using ferrous chelates of SH-containing amino acids and alkali

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, D.K.; Chang, S.G.

1987-04-01

We report herein the use of ferrous chelates of SH-containing amino acids including cysteine, penicillamine, N-acetylcysteine, and N-acetylpenicillamine in neutral or alkaline solutions for the combined removal of NO and SO/sub 2/ in wet flue gas clean-up systems. These SH-containing amino acids not only can stabilize ferrous ions in alkaline solutions to promote the absorption of NO, but are also capable of rapidly reducing ferric ions formed during the scrubbing process back to ferrous ions. The disulfide form of the above amino acids can be reduced by SO/sub 2/ and H/sub 2/S to regenerate the starting monomeric species. The chemistrymore » relevant to the absorption of NO by the above ferrous chelates and the ligand regeneration process will be discussed.« less

Combined NO/sub x//SO/sub 2/ removal from flue gas using ferrous chelates of SH-containing amino acids and alkali

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, D.K.; Chang, S.G.

1987-01-01

We report herein the use of ferrous chelates of SH-containing amino acids including cysteine, penicillamine, N-acetylcysteine, and N-acetylpenicillamine in neutral or alkaline solutions for the combined removal of NO and SO/sub 2/ in wet flue gas clean-up systems. These SH-containing amino acids not only can stabilize ferrous ions in alkaline solutions to promote the absorption of NO, but are also capable of rapidly reducing ferric ions formed during the scrubbing process back to ferrous ions. The disulfide from of the above amino acids can be reduced by SO/sub 2/ and H/sub 2/S to regenerate the starting monomeric species. The chemistrymore » relevant to the absorption of NO by the above ferrous chelates and the ligand regeneration process will be discussed.« less

Femtomolar Ln(III) affinity in peptide-based ligands containing unnatural chelating amino acids.

PubMed

Niedźwiecka, Agnieszka; Cisnetti, Federico; Lebrun, Colette; Delangle, Pascale

2012-05-07

The incorporation of unnatural chelating amino acids in short peptide sequences leads to lanthanide-binding peptides with a higher stability than sequences built exclusively from natural residues. In particular, the hexadentate peptide P(22), which incorporates two unnatural amino acids Ada(2) with aminodiacetate chelating arms, showed picomolar affinity for Tb(3+). To design peptides with higher denticity, expected to show higher affinity for Ln(3+), we synthesized the novel unnatural amino acid Ed3a(2) which carries an ethylenediamine triacetate side-chain and affords a pentadentate coordination site. The synthesis of the derivative Fmoc-Ed3a(2)(tBu)(3)-OH, with appropriate protecting groups for direct use in the solid phase peptide synthesis (Fmoc strategy), is described. The two high denticity peptides P(HD2) (Ac-Trp-Ed3a(2)-Pro-Gly-Ada(2)-Gly-NH(2)) and P(HD5) (Ac-Trp-Ada(2)-Pro-Gly-Ed3a(2)-Gly-NH(2)) led to octadentate Tb(3+) complexes with femtomolar stability in water. The position of the high denticity amino acid Ed3a(2) in the hexapeptide sequence appears to be critical for the control of the metal complex speciation. Whereas P(HD5) promotes the formation of polymetallic species in excess of Ln(3+), P(HD2) forms exclusively the mononuclear complex. The octadentate coordination of Tb(3+) by both P(HD) leads to total dehydration of the metal ion in the mononuclear complexes with long luminescence lifetimes (>2 ms). Hence, we demonstrated that unnatural amino acids carrying polyaminocarboxylate side-chains are interesting building blocks to design high affinity Ln-binding peptides. In particular the novel peptide P(HD2) forms a unique octadentate Tb(3+) complex with femtomolar stability in water and an improvement of the luminescence properties with respect to the trisaquo TbP(22) complex by a factor of 4.

Controlling lipid oxidation via a biomimetic iron chelating active packaging material.

PubMed

Tian, Fang; Decker, Eric A; Goddard, Julie M

2013-12-18

Previously, a siderophore-mimetic metal chelating active packaging film was developed by grafting poly(hydroxamic acid) (PHA) from the surface of polypropylene (PP) films. The objective of the current work was to demonstrate the potential applicability of this PP-g-PHA film to control iron-promoted lipid oxidation in food emulsions. The iron chelating activity of this film was investigated, and the surface chemistry and color intensity of films were also analyzed after iron chelation. In comparison to the iron chelating activity in the free Fe(3+) solution, the PP-g-PHA film retained approximately 50 and 30% of its activity in nitrilotriacetic acid (NTA)/Fe(3+) and citric acid/Fe(3+) solutions, respectively (pH 5.0), indicating a strong chelating strength for iron. The ability of PP-g-PHA films to control lipid oxidation was demonstrated in a model emulsion system (pH 3.0). PP-g-PHA films performed even better than ethylenediaminetetraacetic acid (EDTA) in preventing the formation of volatile oxidation products. The particle size and ζ potential results of emulsions indicated that PP-g-PHA films had no adverse effects on the stability of the emulsion system. Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) analysis suggested a non-migratory nature of the PP-g-PHA film surface. These results suggest that such biomimetic, non-migratory metal chelating active packaging films have commercial potential in protecting foods against iron-promoted lipid oxidation.

Modification of carbon fiber surfaces via grafting with Meldrum's acid

NASA Astrophysics Data System (ADS)

Cuiqin, Fang; Jinxian, Wu; Julin, Wang; Tao, Zhang

2015-11-01

The mechanism of Meldrum's acid modifying carbon fiber surfaces was investigated in this work. The existing carbonyl groups of carbon fibers were grafted with Meldrum's acid to create carboxylic functionalized surfaces. The surface functionalization effect was detected with X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), atomic force microscopy (AFM), and thermogravimetric analysis (TGA). The XPS results showed that the relative content of carboxylic groups on carbon fiber surfaces was increased from initial 1.41% to 7.84%, however, that of carbonyl groups was decreased from 23.11% to 13.28% after grafting reaction. The SEM, AFM and TGA results indicated that the surfaces of carbon fibers neither etched nor generated coating. The tensile strength of carbon fibers was preserved after grafting reaction according to single fiber tensile strength tests. The fibers were well combined with matrix and the maximal interlaminar shear strength (ILSS) of carbon fiber/epoxy resin composites was sharply increased approximately 74% after functionalization. The effects of acetic acid and sonication on the degree of the surface functionalization were also studied.

Glucose-Sensitive Hydrogel Optical Fibers Functionalized with Phenylboronic Acid.

PubMed

Yetisen, Ali K; Jiang, Nan; Fallahi, Afsoon; Montelongo, Yunuen; Ruiz-Esparza, Guillermo U; Tamayol, Ali; Zhang, Yu Shrike; Mahmood, Iram; Yang, Su-A; Kim, Ki Su; Butt, Haider; Khademhosseini, Ali; Yun, Seok-Hyun

2017-04-01

Hydrogel optical fibers are utilized for continuous glucose sensing in real time. The hydrogel fibers consist of poly(acrylamide-co-poly(ethylene glycol) diacrylate) cores functionalized with phenylboronic acid. The complexation of the phenylboronic acid and cis-diol groups of glucose enables reversible changes of the hydrogel fiber diameter. The analyses of light propagation loss allow for quantitative glucose measurements within the physiological range. © 2017 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

New tris(dopamine) derivative as an iron chelator. Synthesis, solution thermodynamic stability, and antioxidant research.

PubMed

Zhang, Qingchun; Jin, Bo; Shi, Zhaotao; Wang, Xiaofang; Lei, Shan; Tang, Xingyan; Liang, Hua; Liu, Qiangqiang; Gong, Mei; Peng, Rufang

2017-06-01

A new tris(dopamine) derivative, containing three dopamine chelate moieties which were attached to a trimesic acid molecular scaffold, has been prepared and fully characterized by NMR, FTIR and HRMS. The solution thermodynamic stability of the chelator with Fe(III), Mg(II), Zn(II) and Fe(II) ions was investigated. Results demonstrated that the chelator exhibited effective binding ability and improved selectivity to Fe(III) ion. The chelator possessed affinity similar to that of diethylenetriaminepentaacetic acid chelator for Fe(III) ion. The high affinity could be attributed to the favorable geometric arrangement between the chelator and Fe(III) ion coordination preference. The chelator also exhibited high antioxidant activity and nontoxicity to neuron-like rat pheochromocytoma cells. Hence, the chelator could be used as chelating agent for iron overload situations without depleting essential metal ions, such as Mg(II) and Zn(II) ions. Copyright © 2017. Published by Elsevier Inc.

Bactericidal Activity of Usnic Acid-Loaded Electrospun Fibers.

PubMed

Araújo, Evando S; Pereira, Eugênia C; da Costa, Mateus M; da Silva, Nicácio H; de Oliveira, Helinando P

2016-01-01

Usnic acid has been progressively reported in the literature as one of the most important lichen metabolites characterized by a rich diversity of applications such as antifungal, antimicrobial, antiprotozoal and antiviral agent. Particularly, antimicrobial activity of usnic acid can be improved by encapsulation of active molecules in enteric electrospun fibers, allowing the controlled release of active molecule at specific pH. Few relevant patents to the topic have been reviewed and cited. Bactericidal activity of usnic acid-loaded electrospun fibers of Eudragit L-100 and polyvinylpyrrolidone was examined against Staphylococcus aureus using inhibition hales methodology. The controlled release of active material at high pH is established after 10 minutes of interaction with media and results in reasonable activity against S. aureus, as detected by inhibition hales. The strong biological activity of usnic acid-loaded electrospun fibers provides a promising application for corresponding material as a bactericidal agent for wound healing treatment.

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

USGS Publications Warehouse

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

1996-01-01

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

Investigation of irradiated rats DNA in the presence of Cu(II) chelates of amino acids Schiff bases.

PubMed

Karapetyan, N H; Torosyan, A L; Malakyan, M; Bajinyan, S A; Haroutiunian, S G

2016-01-01

The new synthesized Cu(II) chelates of amino acids Schiff bases were studied as a potential radioprotectors. Male albino rats of Wistar strain were exposed to X-ray whole-body irradiation at 4.8 Gy. This dose caused 30% mortality of the animals (LD30). The survival of animals exposed to radiation after preliminary administration of 10 mg/kg Cu(II)(Nicotinyl-L-Tyrosinate)2 or Cu(II)(Nicotinyl-L-Tryptophanate)2 prior to irradiation was registered about 80 and 100% correspondingly. Using spectrophotometric melting and agarose gel electrophoresis methods, the differences between the DNA isolated from irradiated rats and rats pretreated with Cu(II) chelates were studied. The fragments of DNA with different breaks were revealed in DNA samples isolated from irradiated animals. While, the repair of the DNA structure was observed for animals pretreated with the Cu(II) chelates. The results suggested that pretreatment of the irradiated rats with Cu(II)(Nicotinyl-L-Tyrosinate)2 and Cu(II)(Nicotinyl-L-Tryptophanate)2 compounds improves the liver DNA characteristics.

Removal of heavy metal species from industrial sludge with the aid of biodegradable iminodisuccinic acid as the chelating ligand.

PubMed

Wu, Qing; Duan, Gaoqi; Cui, Yanrui; Sun, Jianhui

2015-01-01

High level of heavy metals in industrial sludge was the obstacle of sludge disposal and resource recycling. In this study, iminodisuccinic acid (IDS), a biodegradable chelating ligand, was used to remove heavy metals from industrial sludge generated from battery industry. The extraction of cadmium, copper, nickel, and zinc from battery sludge with aqueous solution of IDS was studied under various conditions. It was found that removal efficiency greatly depends on pH, chelating agent's concentration, as well as species distribution of metals. The results showed that mildly acidic and neutral systems were not beneficial to remove cadmium. About 68 % of cadmium in the sample was extracted at the molar ratio of IDS to heavy metals 7:1 without pH adjustment (pH 11.5). Copper of 91.3 % and nickel of 90.7 % could be removed by IDS (molar ratio, IDS: metals = 1:1) with 1.2 % phosphoric acid effectively. Removal efficiency of zinc was very low throughout the experiment. Based on the experimental results, IDS could be a potentially useful chelant for heavy metal removal from battery industry sludge.

Reusable chelating resins concentrate metal ions from highly dilute solutions

NASA Technical Reports Server (NTRS)

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

1966-01-01

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

A review of pitfalls and progress in chelation treatment of metal poisonings.

PubMed

Andersen, Ole; Aaseth, Jan

2016-12-01

Most acute and chronic human metal poisonings are due to oral or inhalation exposure. Almost 80% of published animal experiments on chelation in metal poisoning used single or repeated intraperitoneal, intramuscular or intravenous administration of metal and chelator, impeding extrapolation to clinical settings. Intramuscular administration of dimercaptopropanol (BAL) has until now been used in acute arsenic, lead, and mercury poisonings, but repeated BAL administration increased the brain uptake of As, Pb and Hg in experimental animals. Also, diethyl dithiocarbamate (DDC) has been used as antidote in acute experimental animal parenteral Cd poisoning, and both DDC and tetraethylthiuram disulfide (TTD, disulfiram, Antabuse) have been used in nickel allergic patients. However, even one dose of DDC given immediately after oral Cd or Ni increased their brain uptake considerably. The calcium salt of ethylenediamminetetraacetic acid (CaEDTA) but not dimercaptosuccinic acid (DMSA) increased the brain uptake of Pb. In oral Cd or Hg poisoning, early oral administration of DMSA or dimercaptopropane sulfonate (DMPS) increased survival and reduced intestinal metal uptake. Oral administration of Prussian Blue or resins with fixed chelating groups that are not absorbed offer chelation approaches for decorporation after oral exposure to various metals. Diethylenetriaminepentaacetic acid (DTPA) nebulizers for pulmonary chelation after inhalation exposure need further development. Also, combined chelation with more than one compound may offer extensive advances. Solid knowledge on the chemistry of metal chelates together with relevant animal experiments should guide development of chelation procedures to alleviate and not aggravate the clinical status of poisoned patients. Copyright © 2016 Elsevier GmbH. All rights reserved.

Leaching variations of heavy metals in chelator-assisted phytoextraction by Zea mays L. exposed to acid rainfall.

PubMed

Lu, Yayin; Luo, Dinggui; Liu, Lirong; Tan, Zicong; Lai, An; Liu, Guowei; Li, Junhui; Long, Jianyou; Huang, Xuexia; Chen, Yongheng

2017-11-01

Chelant-enhanced phytoextraction method has been put forward as an effective soil remediation method, whereas the heavy metal leaching could not be ignored. In this study, a cropping-leaching experiment, using soil columns, was applied to study the metal leaching variations during assisted phytoextraction of Cd- and Pb-polluted soils, using seedlings of Zea mays, applying three different chelators (EDTA, EDDS, and rhamnolipid), and artificial rainfall (acid rainfall or normal rainfall). It showed that artificial rainfall, especially artificial acid rain, after chelator application led to the increase of heavy metals in the leaching solution. EDTA increased both Cd and Pb concentrations in the leaching solution, obviously, whereas EDDS and rhamnolipid increased Cd concentration but not Pb. The amount of Cd and Pb decreased as the leaching solution increased, the patterns as well matched LRMs (linear regression models), with R-square (R 2 ) higher than 90 and 82% for Cd and Pb, respectively. The maximum cumulative Cd and Pb in the leaching solutions were 18.44 and 16.68%, respectively, which was amended by EDTA and acid rainwater (pH 4.5), and followed by EDDS (pH 4.5), EDDS (pH 6.5), rhamnolipid (0.5 g kg -1 soil, pH 4.5), and rhamnolipid (pH 6.5).

Photo-Curable Metal-Chelating Coatings Offer a Scalable Approach to Production of Antioxidant Active Packaging.

PubMed

Lin, Zhuangsheng; Goddard, Julie

2018-02-01

Synthetic metal chelators (for example, ethylenediaminetetraacetic acid, EDTA) are widely used as additives to control trace transition metal induced oxidation in consumer products. To enable removal of synthetic chelators in response to increasing consumer demand for clean label products, metal-chelating active food packaging technologies have been developed with demonstrated antioxidant efficacy in simulated food systems. However, prior work in fabrication of metal-chelating materials leveraged batch chemical reactions to tether metal-chelating ligands, a process with limited industrial translatability for large-scale fabrication. To improve the industrial translatability, we have designed a 2-step laminated photo-grafting process to introduce metal chelating functionality onto common polymeric packaging materials. Iminodiacetic acid (IDA) functionalized materials were fabricated by photo-grafting poly(acrylic acid) onto polypropylene (PP) films, followed by a second photo-grafting process to graft-polymerize an IDA functionalized vinyl monomer (GMA-IDA). The photo-grafting was conducted under atmospheric conditions and was completed in 2 min. The resulting IDA functionalized metal-chelating material was able to chelate iron and copper, and showed antioxidant efficacy against ascorbic acid degradation, supporting its potential to be used synergistically with natural antioxidants for preservation of food and beverage products. The 2-step photo-grafting process improves the throughput of active packaging coatings, enabling potential roll-to-roll fabrication of metal-chelating active packaging materials for antioxidant food packaging applications. To address consumer and retail demands for "clean label" foods and beverages without a corresponding loss in product quality and shelf life, producers are seeking next generation technologies such as active packaging. In this work, we will report the synthesis of metal-chelating active packaging films, which enable removal

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

DOEpatents

Raymond, K.N.; Xu, J.

1997-04-29

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

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

DOEpatents

Raymond, Kenneth N.; Xu, Jide

1997-01-01

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

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

DOEpatents

Raymond, K.; Xu, J.

1999-04-06

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

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

DOEpatents

Raymond, Kenneth; Xu, Jide

1999-01-01

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

In vitro and in vivo evaluation of potential aluminum chelators.

PubMed

Graff, L; Muller, G; Burnel, D

1995-10-01

The potential for aluminium (Al) chelation by different compounds was determined using 2 in vitro techniques. The formation of stable complexes with Al in an aqueous solution was evaluated using pulse polarography. This technique allowed the influence of temperature and calcium (Ca) to be studied for each compound. Certain compounds (EDDHA, HAES, citric acid and HBED) showed great chelation in the absence of Ca2+ at a temperature of 37 +/- 1 C. An ultrafiltration technique combined with Al determination by atomic emission spectroscopy allowed the efficiency of different substances to complex Al that were previously bound to serum proteins to be estimated. The kinetics of chelation and minimum efficient concentration have been determined for all products studied. EDDHA had chelation potential similar to DFO. The real efficacies of the compounds were studied in vivo to compare the effectiveness of repeated administrations of the best chelating agents (EDDHA, DFO, HAES and tartaric acid) on the distribution and excretion of Al after repeated i.p. administrations to rats. Intraperitoneal EDDHA significantly increased urinary metal (Al, Ca, Cu, Fe and Zn) excretion. These excretions may be correlated to a renal toxic potential property.

A new morphological approach for removing acid dye from leather waste water: preparation and characterization of metal-chelated spherical particulated membranes (SPMs).

PubMed

Şenay, Raziye Hilal; Gökalp, Safiye Meriç; Türker, Evren; Feyzioğlu, Esra; Aslan, Ahmet; Akgöl, Sinan

2015-03-15

In this study, p(HEMA-GMA) poly(hydroxyethyl methacrylate-co-glycidyl methacrylate) spherical particulated membranes (SPMs) were produced by UV-photopolymerization and the synthesized SPMs were coupled with iminodiacetic acid (IDA). Finally the novel SPMs were chelated with Cr(III) ions as ligand and used for removing acid black 210 dye. Characterizations of the metal-chelated SPMs were made by SEM, FTIR and swelling test. The water absorption capacities and acid dye adsorption properties of the SPMs were investigated and the results were 245.0, 50.0, 55.0 and 51.9% for p(HEMA), p(HEMA-GMA), p(HEMA-GMA)-IDA and p(HEMA-GMA)-IDA-Cr(III) SPMs respectively. Adsorption properties of the p(HEMA-GMA)-IDA-Cr(III) SPMs were investigated under different conditions such as different initial dye concentrations and pH. The optimum pH was observed at 4.3 and the maximum adsorption capacity was determined as 885.14 mg/g at about 8000 ppm initial dye concentration. The concentrations of the dyes were determined using a UV/Vis Spectrophotometer at a wavelength of 435 nm. Reusability of p(HEMA-GMA)-IDA-Cr(III) SPMs was also shown for five adsorption-desorption cycles without considerable decrease in its adsorption capacity. Finally, the results showed that the metal-chelated p(HEMA-GMA)-IDA SPMs were effective sorbent systems removing acid dye from leather waste water. Copyright © 2014 Elsevier Ltd. All rights reserved.

Comparison of macrocyclic and acyclic chelators for gallium-68 radiolabelling.

PubMed

Tsionou, Maria Iris; Knapp, Caroline E; Foley, Calum A; Munteanu, Catherine R; Cakebread, Andrew; Imberti, Cinzia; Eykyn, Thomas R; Young, Jennifer D; Paterson, Brett M; Blower, Philip J; Ma, Michelle T

2017-10-24

Gallium-68 ( 68 Ga) is a positron-emitting isotope used for clinical PET imaging of peptide receptor expression. 68 Ga radiopharmaceuticals used in molecular PET imaging consist of disease-targeting biomolecules tethered to chelators that complex 68 Ga 3+ . Ideally, the chelator will rapidly, quantitatively and stably coordinate 68 Ga 3+ at room temperature, near neutral pH and low chelator concentration, allowing for simple routine radiopharmaceutical formulation. Identification of chelators that fulfil these requirements will facilitate development of kit-based 68 Ga radiopharmaceuticals. Herein the reaction of a range of widely used macrocyclic and acyclic chelators with 68 Ga 3+ is reported. Radiochemical yields have been measured under conditions of varying chelator concentrations, pH (3.5 and 6.5) and temperature (25 and 90 °C). These chelators are: 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA), 1,4,7-triazacyclononane-1,4,7-triacetic acid (NOTA), 1,4,7-triazacyclononane macrocycles substituted with phosphonic (NOTP) and phosphinic (TRAP) groups at the amine, bis(2-hydroxybenzyl)ethylenediaminediacetic acid (HBED), a tris(hydroxypyridinone) containing three 1,6-dimethyl-3-hydroxypyridin-4-one groups (THP) and the hexadentate tris(hydroxamate) siderophore desferrioxamine-B (DFO). Competition studies have also been undertaken to assess relative complexation efficiencies of each chelator for 68 Ga 3+ under different pH and temperature conditions. Performing radiolabelling reactions at pH 6.5, 25 °C and 5-50 μM chelator concentration resulted in near quantitative radiochemical yields for all chelators, except DOTA. Radiochemical yields either decreased or were not substantially improved when the reactions were undertaken at lower pH or at higher temperature, except in the case of DOTA. THP and DFO were the most effective 68 Ga 3+ chelators at near-neutral pH and 25 °C, rapidly providing near-quantitative radiochemical yields at very low

Iminodiacetic acid functionalised organopolymer monoliths: application to the separation of metal cations by capillary high-performance chelation ion chromatography.

PubMed

Moyna, Áine; Connolly, Damian; Nesterenko, Ekaterina; Nesterenko, Pavel N; Paull, Brett

2013-03-01

Lauryl methacrylate-co-ethylene dimethacrylate monoliths were polymerised within fused silica capillaries and subsequently photo-grafted with varying amounts of glycidyl methacrylate (GMA). The grafted monoliths were then further modified with iminodiacetic acid (IDA), resulting in a range of chelating ion-exchange monoliths of increasing capacity. The IDA functional groups were attached via ring opening of the epoxy group on the poly(GMA) structure. Increasing the amount of attached poly(GMA), via photo-grafting with increasing concentrations of GMA, from 15 to 35%, resulted in a proportional and controlled increase in the complexation capacity of the chelating monoliths. Scanning capacitively coupled contactless conductivity detection (sC(4)D) was used to characterise and verify homogenous distribution of the chelating ligand along the length of the capillaries non-invasively. Chelation ion chromatographic separations of selected transition and heavy metals were carried out, with retention factor data proportional to the concentration of grafted poly(GMA). Average peak efficiencies of close to 5,000 N/m were achieved, with the isocratic separation of Na, Mg(II), Mn(II), Co(II), Cd(II) and Zn(II) possible on a 250-mm-long monolith. Multiple monolithic columns produced to the same recipes gave RSD data for retention factors of <15% (averaged for several metal ions). The monolithic chelating ion-exchanger was applied to the separation of alkaline earth and transition metal ions spiked in natural and potable waters.

Evaluation of immobilized metal-ion affinity chromatography (IMAC) as a technique for IgG(1) monoclonal antibodies purification: the effect of chelating ligand and support.

PubMed

Bresolin, I T L; Borsoi-Ribeiro, M; Tamashiro, W M S C; Augusto, E F P; Vijayalakshmi, M A; Bueno, S M A

2010-04-01

Monoclonal antibodies (MAbs) have been used for therapies and some analytical procedures as highly purified molecules. Many techniques have been applied and studied, focusing on monoclonal antibodies purification. In this study, an immobilized metal affinity chromatography membrane was developed and evaluated for the purification of anti-TNP IgG(1) mouse MAbs from cell culture supernatant after precipitation with a 50% saturated ammonium sulfate solution. The chelating ligands iminodiacetic acid, carboxymethylated aspartic acid (CM-Asp), nitrilotriacetic acid, and tris (carboxymethyl) ethylenediamine in agarose gels with immobilized Ni(II) and Zn(II) ions were compared for the adsorption and desorption of MAbs. The most promising chelating ligand--CM-Asp--was then coupled to poly(ethylene vinyl alcohol) (PEVA) hollow fiber membranes. According to SDS-PAGE and ELISA analyses, a higher selectivity and a purification factor of 85.9 (fraction eluted at 500 mM Tris) were obtained for IgG(1) using PEVA-CM-Asp-Zn(II). The anti-TNP MAb could be eluted under mild pH conditions causing no loss of antigen binding capacity.

Comparison of synthetic chelators and low molecular weight organic acids in enhancing phytoextraction of heavy metals by two ecotypes of Sedum alfredii Hance.

PubMed

Liu, Dan; Islam, Ejazul; Li, Tingqiang; Yang, Xiaoe; Jin, Xiaofen; Mahmood, Qaisar

2008-05-01

Lab scale and pot experiments were conducted to compare the effects of synthetic chelators and low molecular weight organic acids (LMWOA) on the phytoextraction of multi-contaminated soils by two ecotypes of Sedum alfredii Hance. Through lab scale experiments, the treatment dosage of 5 and 10 mM for synthetic chelators and LMWOA, respectively, and the treatment time of 10 days were selected for pot experiment. In pot experiment, the hyperaccumulating ecotype (HE) was found more tolerant to the metal toxicity compared with the non-hyperaccumulating ecotype (NHE). EDTA for Pb, EDDS for Cu, and DTPA for Cu and Cd were found more effective to enhance heavy metal accumulation in the shoots of S. alfredii Hance. Compared with synthetic chelators, the phytoextraction ability of LMWOA was lesser. Considering the strong post-harvest effects of synthetic chelators, it is suggested that higher dosage of LMWOA could be practiced during phytoextraction, and some additional measures could also be taken to lower the potential environmental risks of synthetic chelators in the future studies.

Synthesis of Copper-Chelates Derived from Amino Acids and Evaluation of Their Efficacy as Copper Source and Growth Stimulator for Lactuca sativa in Nutrient Solution Culture.

PubMed

Kaewchangwat, Narongpol; Dueansawang, Sattawat; Tumcharern, Gamolwan; Suttisintong, Khomson

2017-11-15

Five tetradentate ligands were synthesized from l-amino acids and utilized for the synthesis of Cu(II)-chelates 1-5. The efficacy of Cu(II)-chelates as copper (Cu) source and growth stimulator in hydroponic cultivation was evaluated with Lactuca sativa. Their stability test was performed at pH 4-10. The results suggested that Cu(II)-chelate 3 is the most pH tolerant complex. Levels of Cu, Zn, and Fe accumulated in plants supplied with Cu(II)-chelates were compared with those supplied with CuSO 4 at the same Cu concentration of 8.0 μM. The results showed that Cu(II)-chelate 3 significantly enhanced Cu, Zn, and Fe content in shoot by 35, 15, and 48%, respectively. Application of Cu(II)-chelate 3 also improved plant dry matter yield by 54%. According to the results, Cu(II)-chelate 3 demonstrated the highest stimulating effect on plant growth and plant mineral accumulation so that it can be used as an alternative to CuSO 4 for supplying Cu in nutrient solutions and enhancing the plant growth.

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

EPA Science Inventory

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...

Lignin-Derived Carbon Fibers as Efficient Heterogeneous Solid Acid Catalysts for Esterification of Oleic Acid

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adhikari, Shiba P.; Hood, Zachary D.; Gallego, Nidia C.

Here, the production of biodiesel by the esterification of oleic acid, as an example of free fatty acid (FFA), was explored by using a new solid acid catalyst derived from lignin, a highly abundant low-cost biomass material. The catalyst was synthesized from lignin-derived carbon fiber by straightforward sulfonation and contains 1.86 mmol/g of sulfonic acid (-SO 3H) groups. The catalyst was characterized by a variety of techniques including PXRD, TGA, TPD-MS, SEM, and XPS to understand the surface chemistry and the result of sulfonation. It was found that the sulfonated lignin-derived carbon fiber (CF-SO 3H) catalyst was very efficient atmore » esterifying oleic acid at 80 oC in 4 hours, with 10 wt. % catalyst (in terms of oleic acid content) and at a 10:1 molar ratio of methanol: oleic acid with a yield of 92%. Furthermore, the catalyst can be reused with no significant loss in activity after 4 cycles. Hence, synthesizing solid acid catalysts from lignin-derived carbon fiber affords a novel strategy for producing biodiesel via ‘green chemistry’.« less

Lignin-Derived Carbon Fibers as Efficient Heterogeneous Solid Acid Catalysts for Esterification of Oleic Acid

DOE PAGES

Adhikari, Shiba P.; Hood, Zachary D.; Gallego, Nidia C.; ...

2018-06-04

Here, the production of biodiesel by the esterification of oleic acid, as an example of free fatty acid (FFA), was explored by using a new solid acid catalyst derived from lignin, a highly abundant low-cost biomass material. The catalyst was synthesized from lignin-derived carbon fiber by straightforward sulfonation and contains 1.86 mmol/g of sulfonic acid (-SO 3H) groups. The catalyst was characterized by a variety of techniques including PXRD, TGA, TPD-MS, SEM, and XPS to understand the surface chemistry and the result of sulfonation. It was found that the sulfonated lignin-derived carbon fiber (CF-SO 3H) catalyst was very efficient atmore » esterifying oleic acid at 80 oC in 4 hours, with 10 wt. % catalyst (in terms of oleic acid content) and at a 10:1 molar ratio of methanol: oleic acid with a yield of 92%. Furthermore, the catalyst can be reused with no significant loss in activity after 4 cycles. Hence, synthesizing solid acid catalysts from lignin-derived carbon fiber affords a novel strategy for producing biodiesel via ‘green chemistry’.« less

NMR structural studies of the supramolecular adducts between a liver cytosolic bile acid binding protein and gadolinium(III)-chelates bearing bile acids residues: molecular determinants of the binding of a hepatospecific magnetic resonance imaging contrast agent.

PubMed

Assfalg, Michael; Gianolio, Eliana; Zanzoni, Serena; Tomaselli, Simona; Russo, Vito Lo; Cabella, Claudia; Ragona, Laura; Aime, Silvio; Molinari, Henriette

2007-11-01

The binding affinities of a selected series of Gd(III) chelates bearing bile acid residues, potential hepatospecific MRI contrast agents, to a liver cytosolic bile acid transporter, have been determined through relaxivity measurements. The Ln(III) complexes of compound 1 were selected for further NMR structural analysis aimed at assessing the molecular determinants of binding. A number of NMR experiments have been carried out on the bile acid-like adduct, using both diamagnetic Y(III) and paramagnetic Gd(III) complexes, bound to a liver bile acid binding protein. The identified protein "hot spots" defined a single binding site located at the protein portal region. The presented findings will serve in a medicinal chemistry approach for the design of hepatocytes-selective gadolinium chelates for liver malignancies detection.

Enhancement effects of chelating agents on the degradation of tetrachloroethene in Fe(III) catalyzed percarbonate system

PubMed Central

Miao, Zhouwei; Gu, Xiaogang; Lu, Shuguang; Brusseau, Mark L.; Zhang, Xiang; Fu, Xiaori; Danish, Muhammad; Qiu, Zhaofu; Sui, Qian

2015-01-01

The performance of Fe(III)-based catalyzed sodium percarbonate (SPC) for stimulating the oxidation of tetrachloroethene (PCE) for groundwater remediation applications was investigated. The chelating agents citric acid monohydrate (CIT), oxalic acid (OA), and Glutamic acid (Glu) significantly enhanced the degradation of PCE. Conversely, ethylenediaminetetraacetic acid (EDTA) had a negative impact on PCE degradation, which may due to its strong Fe chelation and HO• scavenging abilities. However, excessive SPC or chelating agent will retard PCE degradation. In addition, investigations using free radical probe compounds and radical scavengers revealed that PCE was primarily degraded by HO• radical oxidation in both the chelated and non-chelated systems, while O2•− also participated in the non-chelated system and the OA and Glu modified systems. According to the electron paramagnetic resonance (EPR) studies, the presence of HO• in the Fe(III)/SPC system was maintained much longer than that in the Fe(II)/SPC system. The results indicated that the addition of CIT, OA or Glu indeed enhanced the generation of HO• in the first 10 min and promoted degradation efficiency by increasing the amount of Fe(III) and maintaining the concentration of HO• radicals in solution. In conclusion, chelated Fe(III)-based catalyzed SPC oxidation is a promising method for the remediation of PCE-contaminated groundwater. PMID:26549979

Metal-chelating active packaging film enhances lysozyme inhibition of Listeria monocytogenes.

PubMed

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

2014-07-01

Several studies have demonstrated that metal chelators enhance the antimicrobial activity of lysozyme. This study examined the effect of metal-chelating active packaging film on the antimicrobial activity of lysozyme against Listeria monocytogenes. Polypropylene films were surface modified by photoinitiated graft polymerization of acrylic acid (PP-g-PAA) from the food contact surface of the films to impart chelating activity based on electrostatic interactions. PP-g-PAA exhibited a carboxylic acid density of 113 ± 5.4 nmol cm(-2) and an iron chelating activity of 53.7 ± 9.8 nmol cm(-2). The antimicrobial interaction of lysozyme and PP-g-PAA depended on growth media composition. PP-g-PAA hindered lysozyme activity at low ionic strength (2.48-log increase at 64.4 mM total ionic strength) and enhanced lysozyme activity at moderate ionic strength (5.22-log reduction at 120 mM total ionic strength). These data support the hypothesis that at neutral pH, synergy between carboxylate metal-chelating films (pKa(bulk) 6.45) and lysozyme (pI 11.35) is optimal in solutions of moderate to high ionic strength to minimize undesirable charge interactions, such as lysozyme absorption onto film. These findings suggest that active packaging, which chelates metal ions based on ligand-specific interactions, in contrast to electrostatic interactions, may improve antimicrobial synergy. This work demonstrates the potential application of metal-chelating active packaging films to enhance the antimicrobial activity of membrane-disrupting antimicrobials, such as lysozyme.

Rates of cuticular penetration of chelated Fe(III): role of humidity, concentration, adjuvants, temperature, and type of chelate.

PubMed

Schönherr, Jörg; Fernández, Victoria; Schreiber, Lukas

2005-06-01

Time courses of cuticular penetration of FeCl3 and Fe(III) complexes of citric acid, EDTA, EDDHA (Sequestrene 138Fe), imidodisuccinic acid (IDHA), and ligninsulfonic acid (Natrel) were studied using astomatous cuticular membranes (CMs) isolated from Populus x canescens leaves. At 100% relative humidity, the Fe(III) chelates disappeared exponentially with time from the surface of the CMs; that is, penetration was a first-order process that can be described using rate constants or half-times of penetration (t(1/2)). Half-times ranged from 20 to 30 h. At 90% humidity, penetration rates were insignificant with the exception of Natrel, for which t(1/2) amounted to 58 h. Rate constants were independent of temperature (15, 25, and 35 degrees C). Permeability decreased with increasing Fe chelate concentration (IDHA and EDTA). At 100% humidity, half-times measured with FeIDHA were 11 h (2 mmol L(-1)), 17 h (10 mmol L(-1)) and 36 h (20 mmol L(-1)), respectively. In the presence of FeEDTA, penetration of CaCl2 was slowed greatly. Half-times for penetration of CaCl2, which were 1.9 h in the absence of FeEDTA, rose to 3.12 h in the presence of an equimolar concentration of EDTA and 13.3 h when the FeEDTA concentration was doubled. Hence, Fe chelates reduced permeability of CMs to CaCl2 and to the Fe chelates themselves. It is suggested that Fe chelates reduced the size of aqueous pores. This view is supported by the fact that rate constants for calcium salts were about 5 times higher than for Fe chelates with the same molecular weights. Adding Tween 20 (5 g L(-1)) as a humectant did not increase permeability to FeIDHA at 90% humidity and below, while addition of glycine betaine did. Penetration of FeCl3 applied at 5 g L(-1) (pH 1.5) was not a first order process as rate constants decreased rapidly with time. Only 2% of the dose penetrated during the first 2 h and less than that in the subsequent 8 h. Recovery was only 70%. This was attributed to the formation of insoluble Fe

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

PubMed Central

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

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% 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). PMID:22408444

Chelation therapy to prevent diabetes-associated cardiovascular events.

PubMed

Diaz, Denisse; Fonseca, Vivian; Aude, Yamil W; Lamas, Gervasio A

2018-05-24

For over 60 years, chelation therapy with disodium ethylene diamine tetraacetic acid (EDTA, edetate) had been used for the treatment of cardiovascular disease (CVD) despite lack of scientific evidence for efficacy and safety. The Trial to Assess Chelation Therapy (TACT) was developed and received funding from the National Institutes of Health (NIH) to ascertain the safety and efficacy of chelation therapy in patients with CVD. This pivotal trial demonstrated an improvement in outcomes in postmyocardial infarction (MI) patients. Interestingly, it also showed a particularly large reduction in CVD events and all-cause mortality in the prespecified subgroup of patients with diabetes. The TACT results may support the concept of metal chelation to reduce metal-catalyzed oxidation reactions that promote the formation of advanced glycation end products, a precursor of diabetic atherosclerosis. In this review, we summarize the epidemiological and basic evidence linking toxic metal accumulation and diabetes-related CVD, supported by the salutary effects of chelation in TACT. If the ongoing NIH-funded TACT2, in diabetic post-MI patients, proves positive, this unique therapy will enter the armamentarium of endocrinologists and cardiologists seeking to reduce the atherosclerotic risk of their diabetic patients.

Effects of chelating agents on the mineral content of root canal dentin.

PubMed

Cobankara, Funda Kont; Erdogan, Hilal; Hamurcu, Mehmet

2011-12-01

The objective of this in vitro study was to assess the effect of several chelating agents on the mineral content of root dentin. Extracted human mandibular incisor roots were prepared and divided into groups according to the following irrigation protocols: 1) 17% ethylenediaminetetraacetic acid (EDTA); 2) 10% citric acid solution; 3) 18% etidronate; 4) 2.25% peracetic acid; 5) and deionized water (control). Dentin chips were obtained (Gates-Glidden nos. 3, 4, and 5). The levels of different minerals were analyzed with the use of inductively coupled plasma-atomic emission spectrometry (ICP-AES). 1) Peracetic acid significantly decreased P, K, Mg, Na, and S levels compared with the other groups (P < .05). 2) S decreased by different levels in all of the chelating solutions (P < .05), and the greatest decrease was observed in peracetic acid. 3) Ca levels significantly decreased in peracetic acid, citric acid, and EDTA (P < .05). 4) Mn levels significantly decreased in the citric acid and peracetic acid groups (P < .05). 5) Na and Zn levels significantly decreased in the peracetic acid, citric acid, and etidronate groups (P < .05). The chelation agents can create different effects on mineral contents of root dentin, so it is important to know what effects each solution will have on root dentin before their clinical use. In addition, according to the results of this in vitro study, it might be recommended that peracetic acid, in particular, should be used with caution. Copyright © 2011 Mosby, Inc. All rights reserved.

Introducing saccharic acid as an efficient iron chelate to enhance photo-Fenton degradation of organic contaminants.

PubMed

Subramanian, Gokulakrishnan; Madras, Giridhar

2016-11-01

The identification of iron chelates that can enhance photo-Fenton degradation is of great interest in the field of advanced oxidation process. Saccharic acid (SA) is a polyhydroxy carboxylic acid and completely non-toxic. Importantly, it can effectively bind Fe(III) as well as induce photoreduction of Fe(III). Despite having these interesting properties, the effect of SA on photo-Fenton degradation has not been studied. Herein, we demonstrate the first assessment of SA as an iron chelate in photo-Fenton process using methylene blue (MB) as a model organic contaminant. Our results demonstrate that SA has the ability to (i) enhance the photo-Fenton degradation of MB by about 11 times at pH 4.5 (ii) intensify photochemical reduction of Fe(III) to Fe(II) by about 17 times and (iii) accelerate the rate of consumption of H 2 O 2 in photo-Fenton process by about 5 times (iv) increase the TOC reduction by about 2 times and (v) improve the photo-Fenton degradation of MB in the presence of a variety of common inorganic ions and organic matter. The influential properties of SA on photo-Fenton degradation is attributed to the efficient photochemical reduction of Fe(III) via LMCT (ligand to metal charge transfer reaction) to Fe(II), which then activated H 2 O 2 to generate OH and accelerated photo-Fenton degradation efficiency. Moreover, the effect of operational parameters such as oxidant: contaminant (H 2 O 2 : MB) ratio, catalyst: contaminant (Fe(III)SA: MB) ratio, Fe(III): SA stoichiometry and pH on the degradation of MB by photo-Fenton in the presence of SA is demonstrated. Importantly, SA assisted photo-Fenton caused effective degradation of MB and 4-Chlorophenol under natural sunlight irradiation in natural water matrix. The findings strongly support SA as a deserving iron chelate to enhance photo-Fenton degradation. Copyright © 2016 Elsevier Ltd. All rights reserved.

Reactions in glass-ionomer cements: IV. Effect of chelating comonomers on setting behavior.

PubMed

Wilson, A D; Crisp, S; Ferner, A J

1976-01-01

The oscillating rheometer is a valuable instrument for studying the effects of additives on the setting behavior of a cement system. Using this instrument, it was found that certain chelating comonomers, the hydroxycarboxylic acids, could improve the setting characteristics of the glass-ionomer cement system when added to the PAA solution. The acid chelates probably assign the extraction of metal ions from the glass and also tend to hold them in solution, preventing premature ion binding of the polyanion chains. The effect is to increase the rate of hardening without reducing the working time, which may indeed by slightly increased. Tartaric acid, the most effective of the comonomers, can form a chelate bridge between aluminum atoms, and this metal complex probably acts as a flexible bridge structure linking polyanion chains. This mechanism offers some steric advantages over a simple salt bridge.

Experimental Investigation and Analysis of Mercerized and Citric Acid Surface Treated Bamboo Fiber Reinforced Composite

NASA Astrophysics Data System (ADS)

De, Jyotiraman; Baxi, R. N., Dr.

2017-08-01

Mercerization or NaOH fiber surface treatment is one of the most popular surface treatment processes to make the natural fibers such as bamboo fibers compatible for use as reinforcing material in composites. But NaOH being a chemical is hazardous and polluting to the nature. This paper explores the possibility of use of naturally derived citric acid for bamboo fiber surface treatment and its comparison with NaOH treated Bamboo Fiber Composites. Untreated, 2.5 wt% NaOH treated and 5 wt% citric acid treated Bamboo Fiber Composites with 5 wt% fiber content were developed by Hand Lay process. Bamboo mats made of bamboo slivers were used as reinforcing material. Mechanical and physical characterization was done to compare the effects of NaOH and citric acid bamboo fiber surface treatment on mechanical and physical properties of Bamboo Fiber Composite. The experiment data reveals that the tensile and flexural strength was found to be highest for citric acid and NaOH treated Bamboo Fiber Composite respectively. Water absorption tendency was found more than the NaOH treated Bamboo Fiber Composites. SEM micrographs used to analyze the morphology of fracture surface of tensile test specimens confirm improvement in fiber-matrix interface bonding due to surface treatment of bamboo fibers.

The Effect of Acidity Coefficient on Crystallization Behavior of Blast Furnace Slag Fibers

NASA Astrophysics Data System (ADS)

Tian, Tie-Lei; Zhang, Yu-Zhu; Xing, Hong-wei; Li, Jie; Zhang, Zun-Qian

2018-01-01

The chemical structure of mineral wool fiber was investigated by using Fourier Transform Infrared Spectroscopy (FTIR). Next, the glass transition temperature and the crystallization temperature of the fibers were studied. Finally, the crystallization kinetics of fiber was studied. The results show that the chemical bond structure of fibers gets more random with the increase of acidity coefficient. The crystallization phases of the fibers are mainly melilites, and also a few anorthites and diopsides. The growth mechanism of the crystals is three dimensional. The fibers with acidity coefficient of 1.2 exhibit the best thermal stability and is hard to crystallize as it has the maximum aviation energy of crystallization kinetics.

Synthesis and radiolabeling of chelator-RNA aptamer bioconjugates with copper-64 for targeted molecular imaging

PubMed Central

Rockey, William M.; Huang, Ling; Kloepping, Kyle C.; Baumhover, Nicholas J.; Giangrande, Paloma H.; Schultz, Michael K.

2014-01-01

Ribonucleic acid (RNA) aptamers with high affinity and specificity for cancer-specific cell-surface antigens are promising reagents for targeted molecular imaging of cancer using positron emission tomography (PET). For this application, aptamers must be conjugated to chelators capable of coordinating PET-radionuclides (e.g. copper-64, 64Cu) to enable radiolabeling for in vivo imaging of tumors. This study investigates the choice of chelator and radiolabeling parameters such as pH and temperature for the development of 64Cu-labeled RNA-based targeted agents for PET imaging. The characterization and optimization of labeling conditions are described for four chelator-aptamer complexes. Three commercially available bifunctional macrocyclic chelators (1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid mono N-hydroxysuccinimide [DOTA-NHS]; S-2-(4-isothiocyanatobenzyl)-1,4,7-triazacyclononane-1,4,7-triacetic acid [p-SCN-Bn-NOTA]; and p-SCN-Bn-3,6,9,15-tetraazabicyclo [9.3.1]pentadeca-1(15),11,13-triene-3,6,9-triacetic acid [p-SCN-Bn-PCTA]), as well as the polyamino-macrocyclic diAmSar (3,6,10,13,16,19-hexaazabicyclo[6.6.6] icosane-1,8-diamine) were conjugated to A10–3.2, a RNA aptamer which has been shown to bind specifically to a prostate cancer-specific cell-surface antigen (PSMA). Although a commercial bifunctional version of diAmSar was not available, RNA conjugation with this chelator was achieved in a two-step reaction by the addition of a disuccinimidyl suberate linker. Radiolabeling parameters (e.g. pH, temperature, and time) for each chelator-RNA conjugate were assessed in order to optimize specific activity and RNA stability. Furthermore, the radiolabeled chelator-coupled RNA aptamers were evaluated for binding specificity to their target antigen. In summary, key parameters were established for optimal radiolabeling of RNA aptamers for eventual PET imaging with 64Cu. PMID:21658962

Lauric Acid Accelerates Glycolytic Muscle Fiber Formation through TLR4 Signaling.

PubMed

Wang, Leshan; Luo, Lv; Zhao, Weijie; Yang, Kelin; Shu, Gang; Wang, Songbo; Gao, Ping; Zhu, Xiaotong; Xi, Qianyun; Zhang, Yongliang; Jiang, Qingyan; Wang, Lina

2018-06-18

Lauric acid (LA), which is the primary fatty acid in coconut oil, was reported to have many metabolic benefits. TLR4 is a common receptor of lipopolysaccharides and involved mainly in inflammation responses. Here, we focused on the effects of LA on skeletal muscle fiber types and metabolism. We found that 200 μM LA treatment in C2C12 or dietary supplementation of 1% LA increased MHCIIb protein expression and the proportion of type IIb muscle fibers from 0.452 ± 0.0165 to 0.572 ± 0.0153, increasing the mRNA expression of genes involved in glycolysis, such as HK2 and LDH2 (from 1.00 ± 0.110 to 1.35 ± 0.0843 and from 1.00 ± 0.123 to 1.71 ± 0.302 in vivo, respectively), decreasing the catalytic activity of lactate dehydrogenase (LDH), and transforming lactic acid to pyruvic acid. Furthermore, LA activated TLR4 signaling, and TLR4 knockdown reversed the effect of LA on muscle fiber type and glycolysis. Thus, we inferred that LA promoted glycolytic fiber formation through TLR4 signaling.

Supercritical Fluid Extraction of Metal Chelate: A Review.

PubMed

Ding, Xin; Liu, Qinli; Hou, Xiongpo; Fang, Tao

2017-03-04

Supercritical fluid extraction (SFE), as a new green extraction technology, has been used in extracting various metal species. The solubilities of chelating agents and corresponding metal chelates are the key factors which influence the efficiency of SFE. Other main properties of them such as stability and selectivity are also reviewed. The extraction mechanisms of mainly used chelating agents are explained by typical examples in this paper. This is the important aspect of SFE of metal ions. Moreover, the extraction efficiencies of metal species also depend on other factors such as temperature, pressure, extraction time and matrix effect. The two main complexation methods namely in-situ and on-line chelating SFE are described in detail. As an efficient chelating agent, tributyl phosphate-nitric acid (TBP-HNO 3 ) complex attracts much attention. The SFE of metal ions, lanthanides and actinides as well as organometallic compounds are also summarized. With the proper selection of ligands, high efficient extraction of metal species can be obtained. As an efficient sample analysis method, supercritical fluid chromatography (SFC) is introduced in this paper. Recently, the extraction method combining ionic liquids (ILs) with supercritical fluid has been becoming a novel technology for treating metal ions. The kinetics related to SFE of metal species is discussed with some specific examples.

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

PubMed Central

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-tetraazacyclo-dodecane-1,4,7,10-tetraacetic acid (DOTA), and tripeptide GGH were linked to the lysine sidechain of lisinopril by EDC/NHS coupling. The resulting amide-linked chelate-lisinopril (EDTA-lisinopril, NTA-lisinopril, DOTA-lisinopril, and GGH-lisinopril) conjugates were used to form coordination complexes with iron, cobalt, nickel and copper, such that lisinopril could mediate localization of the reactive metal chelates to sACE-1. ACE activity was assayed by monitoring cleavage of the fluorogenic substrate Mca-RPPGFSAFK(Dnp)-OH, a derivative of bradykinin, following pre-incubation with metal-chelate-lisinopril compounds. Concentration-dependent inhibition of sACE-1 by metal-chelate-lisinopril complexes revealed IC50 values ranging from 44 nM to 4,500 nM for Ni-NTA-lisinopril and Ni-DOTA-lisinopril, respectively, versus 1.9 nM for lisinopril. Stronger inhibition was correlated with smaller size and lower negative charge of the attached metal chelates. Time-dependent inactivation of sACE-1 by metal-chelate-lisinopril complexes revealed a remarkable range of catalytic activities, with second order rate constants as high as 150,000 M−1min−1 (Cu-GGH-lisinopril), while catalyst-mediated cleavage of sACE-1 typically occurred at much lower rates, indicating that inactivation arose primary from sidechain modification. Optimal inactivation of sACE-1 was observed when the reduction potential for the metal center was poised near 1000 mV, reflecting the difficulty of protein

Targeted catalytic inactivation of angiotensin converting enzyme by lisinopril-coupled transition-metal chelates.

PubMed

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

2012-02-22

A series of compounds that target reactive transition-metal chelates to somatic angiotensin converting enzyme (sACE-1) have been synthesized. Half-maximal inhibitory concentrations (IC(50)) and rate constants for both inactivation and cleavage of full-length sACE-1 have been determined and evaluated in terms of metal chelate size, charge, reduction potential, coordination unsaturation, and coreactant selectivity. Ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA), and tripeptide GGH were linked to the lysine side chain of lisinopril by 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide hydrochloride/N-hydroxysuccinimide coupling. The resulting amide-linked chelate-lisinopril (EDTA-lisinopril, NTA-lisinopril, DOTA-lisinopril, and GGH-lisinopril) conjugates were used to form coordination complexes with iron, cobalt, nickel, and copper, such that lisinopril could mediate localization of the reactive metal chelates to sACE-1. ACE activity was assayed by monitoring cleavage of the fluorogenic substrate Mca-RPPGFSAFK(Dnp)-OH, a derivative of bradykinin, following preincubation with metal chelate-lisinopril compounds. Concentration-dependent inhibition of sACE-1 by metal chelate-lisinopril complexes revealed IC(50) values ranging from 44 to 4500 nM for Ni-NTA-lisinopril and Ni-DOTA-lisinopril, respectively, versus 1.9 nM for lisinopril. Stronger inhibition was correlated with smaller size and lower negative charge of the attached metal chelates. Time-dependent inactivation of sACE-1 by metal chelate-lisinopril complexes revealed a remarkable range of catalytic activities, with second-order rate constants as high as 150,000 M(-1) min(-1) (Cu-GGH-lisinopril), while catalyst-mediated cleavage of sACE-1 typically occurred at much lower rates, indicating that inactivation arose primarily from side chain modification. Optimal inactivation of sACE-1 was observed when the reduction potential for the

Oxidative degradation stability and hydrogen sulfide removal performance of dual-ligand iron chelate of Fe-EDTA/CA.

PubMed

Miao, Xinmei; Ma, Yiwen; Chen, Zezhi; Gong, Huijuan

2017-09-05

Catalytic oxidation desulfurization using chelated iron catalyst is an effective method to remove H 2 S from various gas streams including biogas. However, the ligand of ethylenediaminetetraacetic acid (EDTA), which is usually adopted to prepare chelated iron catalyst, is liable to be oxidative degraded, and leads to the loss of desulfurization performance. In order to improve the degradation stability of the iron chelate, a series of iron chelates composed of two ligands including citric acid (CA) and EDTA were prepared and the oxidative degradation stability as well as desulfurization performance of these chelated iron catalysts were studied. Results show that the iron chelate of Fe-CA is more stable than Fe-EDTA, while for the desulfurization performance, the situation is converse. For the dual-ligand iron chelates of Fe-EDTA/CA, with the increase of mol ratio of CA to EDTA in the iron chelate solution, the oxidative degradation stability increased while the desulfurization performance decreased. The results of this work showed that Fe-EDTA/CA with a mol ratio of CA:EDTA = 1:1 presents a relative high oxidative degradation stability and an acceptable desulfurization performance with over 90% of H 2 S removal efficiency.

Rates of nickel(II) capture from complexes with NTA, EDDA, and related tetradentate chelating agents by the hexadentate chelating agents EDTA and CDTA: Evidence of a "semijunctive" ligand exchange pathway

NASA Astrophysics Data System (ADS)

Boland, Nathan E.; Stone, Alan T.

2017-09-01

Many siderophores and metallophores produced by soil organisms, as well as anthropogenic chelating agent soil amendments, rely upon amine and carboxylate Lewis base groups for metal ion binding. UV-visible spectra of metal ion-chelating agent complexes are often similar and, as a consequence, whole-sample absorbance measurements are an unreliable means of monitoring the progress of exchange reactions. In the present work, we employ capillary electrophoresis to physically separate Ni(II)-tetradentate chelating agent complexes (NiL) from Ni(II)-hexadentate chelating agent complexes (NiY) prior to UV detection, such that progress of the reaction NiL + Y → NiY + L can be conveniently monitored. Rates of ligand exchange for Ni(II) are lower than for other +II transition metal ions. Ni(II) speciation in environmental media is often under kinetic rather than equilibrium control. Nitrilotriacetic acid (NTA), with three carboxylate groups all tethered to a central amine Lewis base group, ethylenediamine-N,N‧-diacetic acid (EDDA), with carboxylate-amine-amine-carboxylate groups arranged linearly, plus four structurally related compounds, are used as tetradentate chelating agents. Ethylenediaminetetraacetic acid (EDTA) and the structurally more rigid analog trans-cyclohexaneethylenediaminetetraacetic acid (CDTA) are used as hexadentate chelating agents. Effects of pH and reactant concentration are explored. Ni(II) capture by EDTA was consistently more than an order of magnitude faster than capture by CDTA, and too fast to quantify using our capillary electrophoresis-based technique. Using NiNTA as a reactant, Ni(II) capture by CDTA is independent of CDTA concentration and greatly enhanced by a proton-catalyzed pathway at low pH. Using NiEDDA as reactant, Ni(II) capture by CDTA is first order with respect to CDTA concentration, and the contribution from the proton-catalyzed pathway diminished by CDTA protonation. While the convention is to assign either a disjunctive

Iron Chelation

MedlinePlus

... fortified cereals and eggs. What is Iron Chelation Therapy? Drugs called iron chelators remove extra iron from ... form that must be dissolved in juice or water and taken (by mouth) once a day. Most ...

Study of Anti-Fatigue Effect in Rats of Ferrous Chelates Including Hairtail Protein Hydrolysates

PubMed Central

Huang, Saibo; Lin, Huimin; Deng, Shang-gui

2015-01-01

The ability of ferrous chelates including hairtail protein hydrolysates to prevent and reduce fatigue was studied in rats. After hydrolysis of hairtail surimi with papain, the hairtail protein hydrolysates (HPH) were separated into three groups by range of relative molecular weight using ultrafiltration membrane separation. Hairtail proteins were then chelated with ferrous ions, and the antioxidant activity, the amino acid composition and chelation rate of the three kinds of ferrous chelates including hairtail protein hydrolysates (Fe-HPH) were determined. Among the three groups, the Fe-HPH chelate showing the best conditions was selected for the anti-fatigue animal experiment. For it, experimental rats were randomly divided into seven groups. Group A was designated as the negative control group given distilled water. Group B, the positive control group, was given glutathione. Groups C, D and E were designated as the Fe-HPH chelate treatment groups and given low, medium, and high doses, respectively. Group F was designated as HPH hydrolysate treatment group, and Group G was designated as FeCl2 treatment group. The different diets were orally administered to rats for 20 days. After that time, rats were subjected to forced swimming training after 1 h of gavage. Rats given Fe-FPH chelate had higher haemoglobin regeneration efficiency (HRE), longer exhaustive swimming time and higher SOD activity. Additionally, Fe-FPH chelate was found to significantly decrease the malondialdehyde content, visibly enhance the GSH-Px activity in liver and reduce blood lactic acid of rats. Fe-HPH chelate revealed an anti-fatigue effect, similar to or better than the positive control substance and superior to HPH or Fe when provided alone. PMID:26633476

Responses of single facial taste fibers in the channel catfish, Ictalurus punctatus, to amino acids.

PubMed

Kohbara, J; Michel, W; Caprio, J

1992-10-01

1. Amino acids and nucleotides stimulate taste receptors of teleosts. In this report, responses to these compounds of 105 facial taste fibers (79 fully characterized) that innervate maxillary barbel taste buds of the channel catfish (Ictalurus punctatus) were analyzed. 2. The fully characterized facial taste fibers that responded to amino acids (n = 68) were generally poorly responsive to nucleotides and related substances (NRS), whereas the fibers responsive to NRS (n = 11) were poorly responsive to amino acids. Spike discharge of the amino acid-responsive fibers to the most potent amino acid stimulus tested per fiber increased 44-fold from a mean spontaneous activity of 2.1 +/- 3.5 to 92.1 +/- 42.4 (SD) spikes/3 s. Spike activity of the NRS-responsive fibers to NRS increased 11.5-fold from a mean spontaneous activity of 3.4 +/- 5.9 to 39.1 +/- 27.4 spikes/3 s. There was no significant difference between the spontaneous rates, but stimulus evoked spike rates for the amino acid-responsive fibers were significantly greater (P < 0.05; Mann-Whitney test) than those for the NRS-responsive fibers. 3. Hierarchical cluster analysis based on the 3-s response time identified three major groups of neurons. The identified clusters comprised neurons that were highly responsive to either L-alanine (i.e., Ala cluster; n = 39), L-arginine (i.e., Arg cluster; n = 29), or NRS (NRS cluster; n = 11). Fibers comprising the Arg cluster were more narrowly tuned than those within the Ala cluster. This report further characterizes the responses to amino acids of the individual facial taste fibers comprising the Ala and Arg clusters. 4. Subclusters were evident within both of the amino acid-responsive clusters. The Arg cluster was divisible into two subclusters dependent on the response to 1 mM L-proline. Twelve neurons that were significantly (P < 0.05; Mann-Whitney test) more responsive to L-proline than the remaining 17 neurons within the Arg cluster formed the Arg/Pro subcluster; these

Starch/fiber/poly(lactic acid) foam and compressed foam composites

USDA-ARS?s Scientific Manuscript database

Composites of starch, fiber, and poly(lactic acid) (PLA) were made using a foam substrate formed by dehydrating starch or starch/fiber gels. PLA was infiltrated into the dry foam to provide better moisture resistance. Foam composites were compressed into plastics using force ranging from 4-76MPa. Te...

Super-Chelators for Advanced Protein Labeling in Living Cells.

PubMed

Gatterdam, Karl; Joest, Eike F; Dietz, Marina S; Heilemann, Mike; Tampé, Robert

2018-05-14

Live-cell labeling, super-resolution microscopy, single-molecule applications, protein localization, or chemically induced assembly are emerging approaches, which require specific and very small interaction pairs. The minimal disturbance of protein function is essential to derive unbiased insights into cellular processes. Herein, we define a new class of hexavalent N-nitrilotriacetic acid (hexaNTA) chelators, displaying the highest affinity and stability of all NTA-based small interaction pairs described so far. Coupled to bright organic fluorophores with fine-tuned photophysical properties, the super-chelator probes were delivered into human cells by chemically gated nanopores. These super-chelators permit kinetic profiling, multiplexed labeling of His 6 - and His 12 -tagged proteins as well as single-molecule-based super-resolution imaging. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

An investigation into the surface heterogeneity of nitric acid oxidized carbon fiber

NASA Astrophysics Data System (ADS)

Woodhead, Andrea L.; de Souza, Mandy L.; Church, Jeffrey S.

2017-04-01

The carbon fiber surface plays a critical role in the performance of carbon fiber composite materials and, thus it is important to have a thorough understanding of the fiber surface. A series of nitric acid treated intermediate modulus carbon fibers with increasing treatment level was prepared and characterized using a range of surface sensitive techniques including Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), X-ray Photoelectron Spectroscopy (XPS) and Raman spectroscopy. The results, which were found to be consistent with increasing treatment levels, were compared to the literature. Raman spectral mapping has been used to investigate the heterogeneity of the carbon fiber surface after nitric acid oxidation. The mapping enabled the effects of surface treatment on carbon fiber to be investigated at a spatial resolution unattainable by XPS and provided chemical structure information not provided by SEM or AFM. The highest level of treatment resulted in the most heterogeneous surface. Raman mapping, while time consuming, can provide valuable information which can lead to an enhanced understanding of the heterogeneity of the carbon fiber surface.

Liposome encapsulation of chelating agents

DOEpatents

Rahman, Yueh Erh

1976-01-13

A method for transferring a chelating agent across a cellular membrane by encapsulating the charged chelating agent within liposomes and carrying the liposome-encapsulated chelating agent to the cellular membrane where the liposomes containing the chelating agent will be taken up by the cells, thereby transferring the chelating agent across the cellular membrane. A chelating agent can be introduced into the interior of a cell of a living organism wherein the liposomes will be decomposed, releasing the chelating agent to the interior of the cell. The released chelating agent will complex intracellularly deposited toxic heavy metals, permitting the more soluble metal complex to transfer across the cellular membrane from the cell and subsequently be removed from the living organism.

Cellular conditions of weakly chelated magnesium ions strongly promote RNA stability and catalysis.

PubMed

Yamagami, Ryota; Bingaman, Jamie L; Frankel, Erica A; Bevilacqua, Philip C

2018-06-01

Most RNA folding studies have been performed under non-physiological conditions of high concentrations (≥10 mM) of Mg 2+ free , while actual cellular concentrations of Mg 2+ free are only ~1 mM in a background of greater than 50 mM Mg 2+ total . To uncover cellular behavior of RNA, we devised cytoplasm mimic systems that include biological concentrations of amino acids, which weakly chelate Mg 2+ . Amino acid-chelated Mg 2+ (aaCM) of ~15 mM dramatically increases RNA folding and prevents RNA degradation. Furthermore, aaCM enhance self-cleavage of several different ribozymes, up to 100,000-fold at Mg 2+ free of just 0.5 mM, indirectly through RNA compaction. Other metabolites that weakly chelate magnesium offer similar beneficial effects, which implies chelated magnesium may enhance RNA function in the cell in the same way. Overall, these results indicate that the states of Mg 2+ should not be limited to free and bound only, as weakly bound Mg 2+ strongly promotes RNA function under cellular conditions.

Environmentally relevant concentrations of aminopolycarboxylate chelating agents mobilize Cd from humic acid.

PubMed

North, Ashley E; Sarpong-Kumankomah, Sophia; Bellavie, Andrew R; White, Wade M; Gailer, Jürgen

2017-07-01

Although Cd is a pollutant of public health relevance, many dietary sources from which it can be absorbed into human tissues remain unknown. While it is well established that the biogeochemical cycle of Cd involves its complexation with environment-derived ligands (e.g., humic acids, HAs) and anthropogenic ones (e.g., chelating agents, CAs), the interaction of Cd with both of these ligands is less well understood. To gain insight, a HA-Cd complex was injected on a size-exclusion chromatography (SEC) column coupled on-line with a flame atomic absorption spectrometer (FAAS) using 10mmol/L Tris buffer (pH8.0) as the mobile phase. This approach allowed us to observe the intact HA-Cd complex and the retention behavior of Cd as a function of 2-20μmol/L concentrations of ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA) or methylglycinediacetic acid (MGDA) that were added to the mobile phase. An increase of the retention time of Cd was indicative of a partial or complete abstraction of Cd from HA. Our results revealed that all CAs abstracted Cd from the HA-Cd complex at concentrations of 5μmol/L, while MGDA and DTPA were effective at 2μmol/L. The bioavailability of some of the on-column formed CA-Cd complexes explains the previously reported increased accumulation of Cd in periphyton in the ecosystem downstream of wastewater treatment plants. In addition, our results imply that the use of effluents which contain CAs and Cd for the irrigation of food crops can introduce Cd into the food supply and compromise food safety. Copyright © 2017. Published by Elsevier B.V.

The effect of fiber bleaching treatment on the properties of poly(lactic acid)/oil palm empty fruit bunch fiber composites.

PubMed

Rayung, Marwah; Ibrahim, Nor Azowa; Zainuddin, Norhazlin; Saad, Wan Zuhainis; Razak, Nur Inani Abdul; Chieng, Buong Woei

2014-08-22

In this work, biodegradable composites from poly(lactic acid) (PLA) and oil palm empty fruit bunch (OPEFB) fiber were prepared by melt blending method. Prior to mixing, the fiber was modified through bleaching treatment using hydrogen peroxide. Bleached fiber composite showed an improvement in mechanical properties as compared to untreated fiber composite due to the enhanced fiber/matrix interfacial adhesion. Interestingly, fiber bleaching treatment also improved the physical appearance of the composite. The study was extended by blending the composites with commercially available masterbatch colorant.

The Effect of Fiber Bleaching Treatment on the Properties of Poly(lactic acid)/Oil Palm Empty Fruit Bunch Fiber Composites

PubMed Central

Rayung, Marwah; Ibrahim, Nor Azowa; Zainuddin, Norhazlin; Saad, Wan Zuhainis; Razak, Nur Inani Abdul; Chieng, Buong Woei

2014-01-01

In this work, biodegradable composites from poly(lactic acid) (PLA) and oil palm empty fruit bunch (OPEFB) fiber were prepared by melt blending method. Prior to mixing, the fiber was modified through bleaching treatment using hydrogen peroxide. Bleached fiber composite showed an improvement in mechanical properties as compared to untreated fiber composite due to the enhanced fiber/matrix interfacial adhesion. Interestingly, fiber bleaching treatment also improved the physical appearance of the composite. The study was extended by blending the composites with commercially available masterbatch colorant. PMID:25153628

Asbestos-induced endothelial cell activation and injury. Demonstration of fiber phagocytosis and oxidant-dependent toxicity.

PubMed

Garcia, J G; Gray, L D; Dodson, R F; Callahan, K S

1988-10-01

Vascular endothelial cell injury is important in the development of a variety of chronic interstitial lung disorders. However, the involvement of such injury in the inflammatory response associated with the inhalation of asbestos fibers is unclear and the mechanism of asbestos fiber cytotoxicity remains unknown. In the present study, human umbilical vein endothelial cells were challenged with amosite asbestos and several parameters of cellular function were examined. Electron microscopic examination revealed that endothelial cell exposure to asbestos resulted in active phagocytosis of these particulates. Biochemical evidence of dose-dependent asbestos-mediated endothelial cell activation was indicated by increased metabolism of arachidonic acid. For example, amosite asbestos (500 micrograms/ml) produced a ninefold increase in prostacyclin (PGI2) levels over those levels in non-exposed cells. Incubation of human endothelial cells with asbestos fibers induced specific 51Cr release in both a dose- and time-dependent fashion indicative of cellular injury. Injury induced by amosite asbestos was not significantly attenuated by treatment of the endothelial cell monolayer with either the iron chelator deferoxamine, which prevents hydroxyl radical (.OH) formation, or by the superoxide anion (O2-) scavenger, superoxide dismutase. However, significant dose-dependent protection was observed with the hydrogen peroxide (H2O2) scavenger, catalase. Chelation of elemental iron present within amosite asbestos fibers by deferoxamine produced a 33% reduction in asbestos cytotoxicity, suggesting a potential role for hydroxyl radical-mediated injury via the iron-catalyzed Haber-Weiss reaction.(ABSTRACT TRUNCATED AT 250 WORDS)

Attenuation of hippocampal mossy fiber long-term potentiation by low micromolar concentrations of zinc.

PubMed

Takeda, Atsushi; Kanno, Shingo; Sakurada, Naomi; Ando, Masaki; Oku, Naoto

2008-10-01

The role of zinc in long-term potentiation (LTP) at hippocampal mossy fiber synapses is controversial because of the contrary results obtained when using zinc chelators. On the basis of the postulation that exogenous zinc enhances the action of zinc released from mossy fibers, mossy fiber LTP after tetanic stimulation (100 Hz, 1 sec) was checked in the presence of exogenous zinc at low micromolar concentrations. Mossy fiber LTP was significantly attenuated in the presence of 5-30 microM ZnCl(2), and the amplitude of field excitatory postsynaptic potentials 60 min after tetanic stimulation was decreased to almost the basal level. Mossy fiber LTP was also attenuated in the presence of 5 microM ZnCl(2) 5 min after tetanic stimulation. The present study is the first to demonstrate that low micromolar concentrations of zinc attenuate mossy fiber LTP. When mossy fiber LTP was induced in the presence of CaEDTA and ZnAF-2 DA, a membrane-impermeable and a membrane-permeable zinc chelator, respectively, extracellular and intracellular chelation of zinc enhanced a transient posttetanic potentiation (PTP) without altering LTP. It is likely that zinc released by tetanic stimulation is immediately taken up into the mossy fibers and attenuates mossy fiber PTP. These results suggest that attenuation of PTP rather than LTP at mossy fiber synapses is a more physiological role for endogenous zinc. Targeting molecules of zinc in mossy fiber LTP seem to be different between during and after LTP induction because of the differential synaptic activity between them. (c) 2008 Wiley-Liss, Inc.

Relative contribution of phytates, fibers, and tannins to low iron and zinc in vitro solubility in pearl millet (Pennisetum glaucum) flour and grain fractions.

PubMed

Lestienne, Isabelle; Caporiccio, Bertrand; Besançon, Pierre; Rochette, Isabelle; Trèche, Serge

2005-10-19

In vitro digestions were performed on pearl millet flours with decreased phytate contents and on two dephytinized or nondephytinized pearl millet grain fractions, a decorticated fraction, and a bran fraction with low and high fiber and tannin contents, respectively. Insoluble residues of these digestions were then incubated with buffer or enzymatic solutions (xylanases and/or phytases), and the quantities of indigestible iron and zinc released by these different treatments were determined. In decorticated pearl millet grain, iron was chelated by phytates and by insoluble fibers, whereas zinc was almost exclusively chelated by phytates. In the bran of pearl millet grain, a high proportion of iron was chelated by iron-binding phenolic compounds, while the rest of iron as well as the majority of zinc were chelated in complexes between phytates and fibers. The low effect of phytase action on iron and zinc solubility of bran of pearl millet grain shows that, in the case of high fiber and tannin contents, the chelating effect of these compounds was higher than that of phytates.

Role of Coordination and Chelation in Utilization of Nutritionally Essential Trace Elements.

DTIC Science & Technology

BIOCHEMISTRY, *TRANSITION METALS), (*CHELATE COMPOUNDS, BIOCHEMISTRY), (*DIALYSIS, CHEMICAL ANALYSIS), NUTRITION , IRON, CHROMIUM, PHOSPHATES, AMINO ACIDS, HYDROXIDES, ALCOHOLS, PEPTIDES, MEMBRANES, LIQUID FILTERS

Use of ferrous chelates of SH-containing amino acids and peptides for the removal of NO/sub x/ and SO/sub 2/ from flue gas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chang, S.G.; Littlejohn, D.; Liu, D.K.

1988-11-01

The use of ferrous complexes of SH-containing amino acids and peptides for the removal of NO and SO/sub 2/ in wet flue gas clean-up systems is reported. The ferrous chelates investigated in the present study include those of cysteine, N-acetylcysteine, penicillamine, N-acetylpenicillamine, glutathine, and cysteinylglycine. Compared to conventional chelates such as EDTA, these thioamino acids/peptides not only can stabilize ferrous ion in alkaline solutions to promote the absorption of NO but are also capable of rapidly reducing any ferric ions formed during the scrubbing process back to ferrous ions so that continual absorption of NO can be achieved. In themore » case of ferrous cysteine and ferrous penicillamine, most of the absorbed NO is reduced to N/sub 2/. The disulfide form of several of the thioamino acids/peptides produced upon oxidation can be conveniently reduced by SO/sub 2/ and H/sub 2/S to regenerate the starting materials, thus making possible the recycling of the reagents.« less

Efficacy of chelation therapy to remove aluminium intoxication.

PubMed

Fulgenzi, Alessandro; De Giuseppe, Rachele; Bamonti, Fabrizia; Vietti, Daniele; Ferrero, Maria Elena

2015-11-01

There is a distinct correlation between aluminium (Al) intoxication and neurodegenerative diseases (ND). We demonstrated how patients affected by ND showing Al intoxication benefit from short-term treatment with calcium disodium ethylene diamine tetraacetic acid (EDTA) (chelation therapy). Such therapy further improved through daily treatment with the antioxidant Cellfood. In the present study we examined the efficacy of long-term treatment, using both EDTA and Cellfood. Slow intravenous treatment with the chelating agent EDTA (2 g/10 mL diluted in 500 mL physiological saline administered in 2 h) (chelation test) removed Al, which was detected (using inductively coupled plasma mass spectrometry) in urine samples collected from patients over 12 h. Patients that revealed Al intoxication (expressed in μg per g creatinine) underwent EDTA chelation therapy once a week for ten weeks, then once every two weeks for a further six or twelve months. At the end of treatment (a total of 22 or 34 chelation therapies, respectively), associated with daily assumption of Cellfood, Al levels in the urine samples were analysed. In addition, the following blood parameters were determined: homocysteine, vitamin B12, and folate, as well as the oxidative status e.g. reactive oxygen species (ROS), total antioxidant capacity (TAC), oxidized LDL (oxLDL), and glutathione. Our results showed that Al intoxication reduced significantly following EDTA and Cellfood treatment, and clinical symptoms improved. After treatment, ROS, oxLDL, and homocysteine decreased significantly, whereas vitamin B12, folate and TAC improved significantly. In conclusion, our data show the efficacy of chelation therapy associated with Cellfood in subjects affected by Al intoxication who have developed ND.

Comparison of behavior in muscle fiber regeneration after bupivacaine hydrochloride- and acid anhydride-induced myonecrosis.

PubMed

Akiyama, C; Kobayashi, S; Nonaka, I

1992-01-01

We compared the morphologic characteristics of muscle fiber necrosis and subsequent regeneration after injury induced by intramuscular injections of bupivacaine hydrochloride (BPVC) and a variety of solutions at acid and alkaline pH (acetic anhydride, citric acid buffer, and sodium carbonate buffer). After BPVC injection the necrotic muscle fibers were rapidly invaded by phagocytic cells, followed by active regeneration and very little fibrous scar formation. The regenerating muscle fibers increased rapidly in size and attained complete fiber type differentiation and regained their initial fiber diameter within 1 month. Both alkaline and acid solutions induced muscle fiber necrosis followed by regeneration. Fiber necrosis induced by alkaline buffers and acetic anhydride solutions above pH 5.0 produced changes quite similar to that induced by BPVC. However, injection with 0.1 M acetic anhydride at pH below 4.0 resulted in coagulative necrosis of the injured muscle with very little phagocytic infiltration with poor regenerative activity and dense fibrous tissue scarring. Thus, pH 4.0 appears to be the critical pH determining the type of muscle injury and subsequent poor phagocytic and regenerative activities. This model of acidic acetic anhydride injury may lead to the identification of factors which interfere with regeneration and cause fibrous tissue scarring in human muscular dystrophy.

Cuprizone Intoxication Induces Cell Intrinsic Alterations in Oligodendrocyte Metabolism Independent of Copper Chelation.

PubMed

Taraboletti, Alexandra; Walker, Tia; Avila, Robin; Huang, He; Caporoso, Joel; Manandhar, Erendra; Leeper, Thomas C; Modarelli, David A; Medicetty, Satish; Shriver, Leah P

2017-03-14

Cuprizone intoxication is a common animal model used to test myelin regenerative therapies for the treatment of diseases such as multiple sclerosis. Mice fed this copper chelator develop reversible, region-specific oligodendrocyte loss and demyelination. While the cellular changes influencing the demyelinating process have been explored in this model, there is no consensus about the biochemical mechanisms of toxicity in oligodendrocytes and about whether this damage arises from the chelation of copper in vivo. Here we have identified an oligodendroglial cell line that displays sensitivity to cuprizone toxicity and performed global metabolomic profiling to determine biochemical pathways altered by this treatment. We link these changes with alterations in brain metabolism in mice fed cuprizone for 2 and 6 weeks. We find that cuprizone induces widespread changes in one-carbon and amino acid metabolism as well as alterations in small molecules that are important for energy generation. We used mass spectrometry to examine chemical interactions that are important for copper chelation and toxicity. Our results indicate that cuprizone induces global perturbations in cellular metabolism that may be independent of its copper chelating ability and potentially related to its interactions with pyridoxal 5'-phosphate, a coenzyme essential for amino acid metabolism.

Demetalation of Fe, Mn, and Cu chelates and complexes: application to the NMR analysis of micronutrient fertilizers.

PubMed

López-Rayo, Sandra; Lucena, Juan J; Laghi, Luca; Cremonini, Mauro A

2011-12-28

The application of nuclear magnetic resonance (NMR) for the quality control of fertilizers based on Fe(3+), Mn(2+), and Cu(2+) chelates and complexes is precluded by the strong paramagnetism of metals. Recently, a method based on the use of ferrocyanide has been described to remove iron from commercial iron chelates based on the o,o-EDDHA [ethylenediamine-N,N'bis(2-hydroxyphenylacetic)acid] chelating agent for their analysis and quantification by NMR. The present work extended that procedure to other paramagnetic ions, manganese and copper, and other chelating, EDTA (ethylenediaminetetraacetic acid), IDHA [N-(1,2-dicarboxyethyl)-d,l-aspartic acid], and complexing agents, gluconate and heptagluconate. Results showed that the removal of the paramagnetic ions was complete, allowing us to obtain (1)H NMR spectra characterized by narrow peaks. The quantification of the ligands by NMR and high-performance liquid chromatography showed that their complete recovery was granted. The NMR analysis enabled detection and quantification of unknown impurities without the need of pure compounds as internal standards.

Interfacial characteristics of an epoxy composite reinforced with phosphoric acid-functionalized Kevlar fibers

NASA Astrophysics Data System (ADS)

Li, J.; Xia, Y. C.

2010-07-01

A Kevlar fiber was functionalized with the phosphoric acid (PA) of different concentrations. The surface characteristics of the fiber were examined by using the X-ray photoelectron spectroscopy. It was found that the PA functionalization considerably increased the bond strength between the Kevlar fiber and an epoxy matrix.

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

PubMed

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.

Non-enzymatic glucose detection based on phenylboronic acid modified optical fibers

NASA Astrophysics Data System (ADS)

Sun, Xiaolan; Li, Nana; Zhou, Bin; Zhao, Wei; Liu, Liyuan; Huang, Chao; Ma, Longfei; Kost, Alan R.

2018-06-01

A non-enzymatic, sensitive glucose sensor was fabricated based on an evanescent wave absorbing optical fiber probe. The optical fiber sensor was functionalized by fixing a poly (phenylboronic acid) (polyPBA) film onto the conical region of the single mode fiber. The reflected light intensity of the polyPBA-functionalized fiber sensor increased proportionally with glucose concentration in the range of 0-60 mM, and the sensor showed good reproducibility and stability. The developed sensor possessed a high sensitivity of 0.1787%/mM and good linearity. The measurement of glucose concentration in human serum was also demonstrated.

Iron-chelating agents never suppress Fenton reaction but participate in quenching spin-trapped radicals.

PubMed

Li, Linxiang; Abe, Yoshihiro; Kanagawa, Kiyotada; Shoji, Tomoko; Mashino, Tadahiko; Mochizuki, Masataka; Tanaka, Miho; Miyata, Naoki

2007-09-19

Hydroxyl radical formation by Fenton reaction in the presence of an iron-chelating agent such as EDTA was traced by two different assay methods; an electron spin resonance (ESR) spin-trapping method with 5,5-dimethyl-1-pyrroline N-oxide (DMPO), and high Performance liquid chromatography (HPLC)-fluorescence detection with terephthalic acid (TPA), a fluorescent probe for hydroxyl radicals. From the ESR spin-trapping measurement, it was observed that EDTA seemed to suppress hydroxyl radical formation with the increase of its concentration. On the other hand, hydroxyl radical formation by Fenton reaction was not affected by EDTA monitored by HPLC assay. Similar inconsistent effects of other iron-chelating agents such as nitrylotriacetic acid (NTA), diethylenetriamine penta acetic acid (DTPA), oxalate and citrate were also observed. On the addition of EDTA solution to the reaction mixture 10 min after the Fenton reaction started, when hydroxyl radical formation should have almost ceased but the ESR signal of DMPO-OH radicals could be detected, it was observed that the DMPO-OH* signal disappeared rapidly. With the simultaneous addition of Fe(II) solution and EDTA after the Fenton reaction ceased, the DMPO-OH* signal disappeared more rapidly. The results indicated that these chelating agents should enhance the quenching of [DMPO-OH]* radicals by Fe(II), but they did not suppress Fenton reaction by forming chelates with iron ions.

Increased Uptake of Chelated Copper Ions by Lolium perenne Attributed to Amplified Membrane and Endodermal Damage

PubMed Central

Johnson, Anthea; Singhal, Naresh

2015-01-01

The contributions of mechanisms by which chelators influence metal translocation to plant shoot tissues are analyzed using a combination of numerical modelling and physical experiments. The model distinguishes between apoplastic and symplastic pathways of water and solute movement. It also includes the barrier effects of the endodermis and plasma membrane. Simulations are used to assess transport pathways for free and chelated metals, identifying mechanisms involved in chelate-enhanced phytoextraction. Hypothesized transport mechanisms and parameters specific to amendment treatments are estimated, with simulated results compared to experimental data. Parameter values for each amendment treatment are estimated based on literature and experimental values, and used for model calibration and simulation of amendment influences on solute transport pathways and mechanisms. Modeling indicates that chelation alters the pathways for Cu transport. For free ions, Cu transport to leaf tissue can be described using purely apoplastic or transcellular pathways. For strong chelators (ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA)), transport by the purely apoplastic pathway is insufficient to represent measured Cu transport to leaf tissue. Consistent with experimental observations, increased membrane permeability is required for simulating translocation in EDTA and DTPA treatments. Increasing the membrane permeability is key to enhancing phytoextraction efficiency. PMID:26512647

New Polylactic Acid Composites Reinforced with Artichoke Fibers

PubMed Central

Botta, Luigi; Fiore, Vincenzo; Scalici, Tommaso; Valenza, Antonino; Scaffaro, Roberto

2015-01-01

In this work, artichoke fibers were used for the first time to prepare poly(lactic acid) (PLA)-based biocomposites. In particular, two PLA/artichoke composites with the same fiber loading (10% w/w) were prepared by the film-stacking method: the first one (UNID) reinforced with unidirectional long artichoke fibers, the second one (RANDOM) reinforced by randomly-oriented long artichoke fibers. Both composites were mechanically characterized in tensile mode by quasi-static and dynamic mechanical tests. The morphology of the fracture surfaces was analyzed through scanning electron microscopy (SEM). Moreover, a theoretical model, i.e., Hill’s method, was used to fit the experimental Young’s modulus of the biocomposites. The quasi-static tensile tests revealed that the modulus of UNID composites is significantly higher than that of the neat PLA (i.e., ~40%). Moreover, the tensile strength is slightly higher than that of the neat matrix. The other way around, the stiffness of RANDOM composites is not significantly improved, and the tensile strength decreases in comparison to the neat PLA.

Novel chelating agents for iron, manganese, zinc, and copper mixed fertilisation in high pH soil-less cultures.

PubMed

López-Rayo, Sandra; Nadal, Paloma; Lucena, Juan J

2016-03-15

Studies about simultaneous fertilisation with several micronutrients have increased in recent years, as Fe, Mn and Zn deficiencies may appear in the same culture conditions. In fertigation, the replacement of sulfates by synthetic chelates is essential in areas with high pH irrigation water and substrates. Ethylenediamine-N-(2-hydroxyphenylacetic acid)-N'-(4-hydroxyphenylacetic acid) (o,p-EDDHA) and ethylenediamine disuccinic acid (EDDS) are novel chelating agents whose efficacy in simultaneous fertilisation of Zn, Mn and Cu is unknown. This work evaluates the effectiveness of both ligands compared to traditional ligands (EDTA, HEEDTA and DTPA) applied as micronutrient chelate mixtures to soybean and navy bean plants grown in soil-less cultures at high pH by analysing the SPAD and micronutrient nutritional status, including the Composition Nutritional Diagnosis (CND) analysis tool. The application of micronutrients using o,p-EDDHA was more effective in providing Mn and Zn than traditional ligands or sulfates. The application using EDDS increased the Zn nutrition. The results are well correlated with the chemical stability of the formulations. The combined application of Mn and Zn as o,p-EDDHA chelates can represent a more effective source than traditional chelates in micronutrient fertiliser mixtures in soil-less cultures at a high pH. © 2015 Society of Chemical Industry.

Quantitative structure-property relationship (correlation analysis) of phosphonic acid-based chelates in design of MRI contrast agent.

PubMed

Tiwari, Anjani K; Ojha, Himanshu; Kaul, Ankur; Dutta, Anupama; Srivastava, Pooja; Shukla, Gauri; Srivastava, Rakesh; Mishra, Anil K

2009-07-01

Nuclear magnetic resonance imaging is a very useful tool in modern medical diagnostics, especially when gadolinium (III)-based contrast agents are administered to the patient with the aim of increasing the image contrast between normal and diseased tissues. With the use of soft modelling techniques such as quantitative structure-activity relationship/quantitative structure-property relationship after a suitable description of their molecular structure, we have studied a series of phosphonic acid for designing new MRI contrast agent. Quantitative structure-property relationship studies with multiple linear regression analysis were applied to find correlation between different calculated molecular descriptors of the phosphonic acid-based chelating agent and their stability constants. The final quantitative structure-property relationship mathematical models were found as--quantitative structure-property relationship Model for phosphonic acid series (Model 1)--log K(ML) = {5.00243(+/-0.7102)}- MR {0.0263(+/-0.540)}n = 12 l r l = 0.942 s = 0.183 F = 99.165 quantitative structure-property relationship Model for phosphonic acid series (Model 2)--log K(ML) = {5.06280(+/-0.3418)}- MR {0.0252(+/- .198)}n = 12 l r l = 0.956 s = 0.186 F = 99.256.

In vitro screening of Fe2+-chelating effect by a Fenton's reaction-luminol chemiluminescence system.

PubMed

Wada, Mitsuhiro; Komatsu, Hiroaki; Ikeda, Rie; Aburjai, Talal A; Alkhalil, Suleiman M; Kuroda, Naotaka; Nakashima, Kenichiro

2014-11-01

In vitro screening of a Fe(2+) -chelating effect using a Fenton's reaction-luminol chemiluminescence (CL) system is described. The luminescence between the reactive oxygen species generated by the Fenton's reaction and luminol was decreased on capturing Fe(2+) using a chelator. The proposed method can prevent the consumption of expensive seed compounds (drug discovery candidates) owing to the high sensitivity of CL detection. Therefore, the assay could be performed using small volumes of sample solution (150 μL) at micromolar concentrations. After optimization of the screening conditions, the efficacies of conventional chelators such as ethylenediaminetetraacetic acid (EDTA), diethylentriaminepentaacetic acid (DETAPAC), deferoxamine, deferiprone and 1,10-phenanthroline were examined. EC50 values for these compounds (except 1,10-phenanthroline) were in the range 3.20 ± 0.87 to 9.57 ± 0.64 μM (n = 3). Rapid measurement of the Fe(2+)-chelating effect with an assay run time of a few minutes could be achieved using the proposed method. In addition, the specificity of the method was discussed. Copyright © 2014 John Wiley & Sons, Ltd.

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

PubMed Central

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

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-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. PMID:26878770

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

PubMed

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

2016-02-16

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.

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

NASA Astrophysics Data System (ADS)

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.

The Effect of Different Tea Varieties on Iron Chelation

NASA Astrophysics Data System (ADS)

Truong, S. K.; Karim, R.

2016-12-01

The chief objectives of this experiment are to distinguish which type of tea of four variants, pomegranate blackberry green, green, lemon chamomile (herbal), and earl grey (black), are capable of chelating the most iron (III) chloride (FeCl3) through titration. We hypothesized that if each tea variety chelates differing amounts of iron chloride, and if we conduct an experiment in which four different teas are mixed in the same amount of water, iron chloride, and iron chloride indicator EDTA, then the pomegranate blackberry green tea will bind to the most iron due to its large amount of fruit antioxidants. To summarize our methodology, we prepared three solutions of each tea, dissolved with 1 gram of FeCl3 to test three trials per tea variety. The chelation process took place overnight as teas cooled. Six drops of iron chloride indicator added to each solution began the titration. The necessary amount of 0.1M EDTA (ethylenediaminetetraacetic acid) drops required for each solution to turn to a universal amber color from its original dark tone indicates how many free iron molecules were left unbound by the tea solution. After careful analysis of the data, we discovered that blackberry pomegranate green tea possessed the best chelating abilities with 97.48% of FeCl3 adsorbed. Green tea followed with 96.67%. Herbal tea chelated 94.24% of the iron while earl grey absorbed the least amount at 93.43%. From our conclusion, we drew that since blackberry pomegranate green tea contained the highest amount of polyphenols and antioxidants as well as epigallocatechin gallate (EGCG) found in green teas, it was able to chelate the most amount of iron. The substances mentioned in blackberry pomegranate green tea possess the ability to form strong bonds with multiple heavy metals, such as iron (III) chloride atoms. Overall, each variety of tea contains different organic substances. Each of these substances possesses a unique chelating ability, determining how well the type of tea can

Nature of impurities in fertilizers containing EDDHMA/Fe(3+), EDDHSA/Fe(3+), and EDDCHA/Fe(3+) chelates.

PubMed

Alvarez-Fernández, Ana; Cremonini, Mauro A; Sierra, Miguel A; Placucci, Giuseppe; Lucena, Juan J

2002-01-16

Iron chelates derived from ethylenediaminedi(o-hydroxyphenylacetic) acid (EDDHA), ethylenediaminedi(o-hydroxy-p-methylphenylacetic) acid (EDDHMA), ethylenediaminedi(2-hydroxy-5-sulfophenylacetic) acid (EDDHSA), and ethylenediaminedi(5-carboxy-2-hydroxyphenylacetic) acid (EDDCHA) are remarkably efficient in correcting iron chlorosis in plants growing in alkaline soils. This work reports the determination of impurities in commercial samples of fertilizers containing EDDHMA/Fe(3+), EDDHSA/Fe(3+), and EDDCHA/Fe(3+). The active components (EDDHMA/Fe(3+), EDDHSA/Fe(3+), and EDDCHA/Fe(3+)) were separated easily from other compounds present in the fertilizers by HPLC. Comparison of the retention times and the UV-visible spectra of the peaks obtained from commercial EDDHSA/Fe(3+) and EDDCHA/Fe(3+) samples with those of standard solutions showed that unreacted starting materials (p-hydroxybenzenesulfonic acid and p-hydroxybenzoic acid, respectively) were always present in the commercial products. 1D and 2D NMR experiments showed that commercial fertilizers based on EDDHMA/Fe(3+) contained impurities having structures tentatively assigned to iron chelates of two isomers of EDDHMA. These findings suggest that current production processes of iron chelates used in agriculture need to be improved.

Assessment of potential aluminum chelators in an octanol/aqueous system and in the aluminum-loaded rabbit.

PubMed

Yokel, R A; Kostenbauder, H B

1987-11-01

Aluminum (Al) solubilization from Al borate and its distribution in an octanol/aqueous system (Do/w) were determined in the absence and presence of 12 potential Al chelators. Citrate, N,N'-bis-(2-hydroxybenzyl)ethylenediamine- N,N'-diacetic acid (HBED), cyclohexane-1,2-diaminotetraacetic acid (CDTA), diethylenetriaminepentaacetic acid (DTPA), nitrilotriacetic acid (NTA), desferrioxamine, and ethylenediamine-N,N'-bis(2-dihydroxyphenylacetic acid) (EDDHA) were 55 to over 100% efficient in solubilizing equimolar amounts of Al. Tetracycline, EDTA, and 2,3-dihydroxybenzoic acid (DHBA) were less than 20% efficient. 1,4-Dioxane and fluoride were ineffective. The Do/w of Al averaged 0.005. The Do/w of the Al.chelator complex was generally less than that of Al, except for HBED and tetracycline (0.04 and 0.96, respectively). The Do/w of DHBA, desferrioxamine, EDDHA, and HBED were not influenced by Al, but tetracycline became more lipophilic. These compounds were tested for their ability to increase urinary Al excretion in Al-loaded rabbits. Chelators were given po weekly beginning 2 weeks after Al loading. Urine was obtained hourly from 3 hr prior to 6 hr after chelator administration and analyzed for Al. Fluoride and tetracycline (450 and 4500 mumol/kg) and citrate, NTA, EDTA, CDTA, DTPA, DHBA, HBED, and 1,4-dioxane (150 and 1500 mumol/kg) were ineffective. Following HBED administration, some of the Al-loaded rabbits died, presumably due to redistribution of Al within the rabbit. Following DTPA administration, some of the Al-loaded rabbits died, presumably due to DTPA. Oral EDDHA (1500 mumol/kg) significantly increased urinary Al excretion. EDDHA and desferrioxamine (150 mumol/kg) were administered by po, sc, and iv routes and were found to have comparable potency. The in vitro results may explain some of the in vivo findings. The in vitro methods may be useful to screen out compounds with no chelation potential. EDDHA-like compounds may have potential as alternatives to

A novel basalt fiber-reinforced polylactic acid composite for hard tissue repair.

PubMed

Chen, Xi; Li, Yan; Gu, Ning

2010-08-01

A basalt fiber (BF) was, for the first time, introduced into a poly(l-lactic acid) (PLLA) matrix as innovative reinforcement to fabricate composite materials for hard tissue repair. Firstly, BF/PLLA composites and pure PLLA were produced by the methods of solution blending and freeze drying. The results showed that basalt fibers can be uniformly dispersed in the PLLA matrix and significantly improve the mechanical properties and hydrophilicity of the PLLA matrix. The presence of basalt fibers may retard the polymer degradation rate and neutralize the acid degradation from PLLA. Osteoblasts were cultured in vitro to evaluate the cytocompatibility of the composite. An MTT assay revealed that osteoblasts proliferated well for 7 days and there was little difference found in their viability on both PLLA and BF/PLLA films, which was consistent with the alkaline phosphatase (ALP) activity results. A fluorescent staining observation showed that osteoblasts grew well on the composites. SEM images displayed that osteoblasts tended to grow along the fiber axis. The formation of mineralized nodules was observed on the films by Alizarin red S staining. These results suggest that the presence of basalt fibers does not noticeably affect osteoblastic behavior and the designed composites are osteoblast compatible. It is concluded that basalt fibers, as reinforcing fibers, may have promising applications in hard tissue repair.

Site-specific protein labeling with PRIME and chelation-assisted Click chemistry

PubMed Central

Uttamapinant, Chayasith; Sanchez, Mateo I.; Liu, Daniel S.; Yao, Jennifer Z.; White, Katharine A.; Grecian, Scott; Clarke, Scott; Gee, Kyle R.; Ting, Alice Y.

2016-01-01

This protocol describes an efficient method to site-specifically label cell-surface or purified proteins with chemical probes in two steps: PRobe Incorporation Mediated by Enzymes (PRIME) followed by chelation-assisted copper-catalyzed azide-alkyne cycloaddition (CuAAC). In the PRIME step, Escherichia coli lipoic acid ligase site-specifically attaches a picolyl azide derivative to a 13-amino acid recognition sequence that has been genetically fused onto the protein of interest. Proteins bearing picolyl azide are chemoselectively derivatized with an alkyne-probe conjugate by chelation-assisted CuAAC in the second step. We describe herein the optimized protocols to synthesize picolyl azide, perform PRIME labeling, and achieve CuAAC derivatization of picolyl azide on live cells, fixed cells, and purified proteins. Reagent preparations, including synthesis of picolyl azide probes and expression of lipoic acid ligase, take 12 d, while the procedure to perform site-specific picolyl azide ligation and CuAAC on cells or on purified proteins takes 40 min-3 h. PMID:23887180

Effect of compost and biodegradable chelate addition on phytoextraction of copper by Oenothera picensis grown in Cu-contaminated acid soils.

PubMed

González, Isabel; Neaman, Alexander; Cortés, Amparo; Rubio, Patricio

2014-01-01

Oenothera picensis plants (Fragrant Evening Primrose) grow in the acid soils contaminated by Cu smelting in the coastal region of central Chile. We evaluated the effects of compost, at application rate of 5 kg m(-2), and biodegradable chelate MGDA (methylglycinediacetic acid), at application rate of 6 mmol plant(-1), on Cu phytoextraction by O. picensis, in field plots. No significant differences were found between treatments regarding aboveground biomass, shoot Cu concentrations and Cu phytoextraction of O. picensis. This lack of effects of the treatments was provoked by the large variability of soil properties, prior to applying of the treatments. The shoot Cu concentration in O. picensis positively and significantly correlated to exchangeable Cu concentration in the soil. Likewise, the aboveground biomass of O. picensis positively and significantly correlated to soil organic matter content. The Cu phytoextraction by O. picensis, in turn, positively and significantly correlated to both variables, i.e. exchangeable Cu concentration and organic matter content. The average Cu phytoextraction was 1.1 mg plant(-1), which is equivalent to 90 g ha(-1) at planting rate of 8 plants m(-2). In the chelate treatment, Cu phytoextraction was 2.6±2.1 mg plant(-1), which is equivalent to 212±171 g ha(-1) at planting rate of 8 plants m(-2). Copyright © 2013 Elsevier Ltd. All rights reserved.

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

NASA Astrophysics Data System (ADS)

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

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.

PubMed

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

2016-08-08

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

Melt spinning of poly(lactic acid) and hydroxyapatite composite fibers: influence of the filler content on the fiber properties.

PubMed

Persson, Maria; Lorite, Gabriela S; Cho, Sung-Woo; Tuukkanen, Juha; Skrifvars, Mikael

2013-08-14

Composite fibers from poly(lactic acid) (PLA) and hydroxyapatite (HA) particles were prepared using melt spinning. Different loading concentrations of HA particles (i.e., 5, 10, 15, and 20 wt %) in the PLA fibers and solid-state draw ratios (SSDRs) were evaluated in order to investigate their influence on the fibers' morphology and thermal and mechanical properties. A scanning electron microscopy investigation indicated that the HA particles were homogeneously distributed in the PLA fibers. It was also revealed by atomic force microscopy and Fourier transform infrared spectroscopy that HA particles were located on the fiber surface, which is of importance for their intended application in biomedical textiles. Our results also suggest that the mechanical properties were independent of the loading concentration of the HA particles and that the SSDR played an important role in improving the mechanical properties of the composite fibers.

Dietary fiber, organic acids and minerals in selected wild edible fruits of Mozambique.

PubMed

Magaia, Telma; Uamusse, Amália; Sjöholm, Ingegerd; Skog, Kerstin

2013-12-01

The harvesting, utilization and marketing of indigenous fruits and nuts have been central to the livelihoods of the majority of rural communities in African countries. In this study we report on the content of dietary fiber, minerals and selected organic acids in the pulps and kernels of the wild fruits most commonly consumed in southern Mozambique. The content of soluble fiber in the pulps ranged from 4.3 to 65.6 g/100 g and insoluble fiber from 2.6 to 45.8 g/100 g. In the kernels the content of soluble fiber ranged from 8.4 to 42.6 g/100 g and insoluble fiber from 14.7 to 20.9 g/100 g. Citric acid was found in all fruits up to 25.7 g/kg. The kernels of Adansonia digitata and Sclerocarya birrea were shown to be rich in calcium, iron, magnesium and zinc. The data may be useful in selecting wild fruit species appropriate for incorporation into diets.

Amine-reactive forms of a luminescent diethylenetriaminepentaacetic acid chelate of terbium and europium: attachment to DNA and energy transfer measurements.

PubMed

Li, M; Selvin, P R

1997-01-01

An isothiocyanate form of a lanthanide chelate which is highly luminescent when bound to terbium or europium has been synthesized. The chelate consists of diethylenetriaminepentaacetic acid (DTPA) covalently joined to a chromophore, 7-amino-4-methyl-2(1H)-quinolinone (cs124), and to L-p-aminophenylalanine, in which the aromatic amine was further converted to an isothiocyanate group. Ethylenediamine was also used in place of aminophenylalanine, but the isothiocyanate formed from the aliphatic amine was significantly less reactive. Site-specific attachments to triglycine and to the 5' ends of amine-modified DNA oligomers have been made. In addition, as an alternative method of coupling to macromolecules, DTPA anhydride-cs124 can be used to react specifically with a 5' amine group on base-deprotected synthetic DNA oligomers. Synthesis and purification is relatively straightforward in both cases, and luminescent properties are favorable for several applications, including as nonisotopic labels, as long-lifetime alternatives to fluorophores in imaging and diagnostics and particularly as donors in luminescence resonance energy transfer. Energy transfer measurements are consistent with previously reported measurements using different attachment mechanisms.

Synergy and antagonism between iron chelators and antifungal drugs in Cryptococcus.

PubMed

Lai, Yu-Wen; Campbell, Leona T; Wilkins, Marc R; Pang, Chi Nam Ignatius; Chen, Sharon; Carter, Dee A

2016-10-01

Fungal infections remain very difficult to treat, and developing new antifungal drugs is difficult and expensive. Recent approaches therefore seek to augment existing antifungals with synergistic agents that can lower the therapeutic dose, increase efficacy and prevent resistance from developing. Iron limitation can inhibit microbial growth, and iron chelators have been employed to treat fungal infections. In this study, chequerboard testing was used to explore combinations of iron chelators with antifungal agents against pathogenic Cryptococcus spp. with the aim of determining how disruption to iron homeostasis affects antifungal susceptibility. The iron chelators ethylenediaminetetraacetic acid (EDTA), deferoxamine (DFO), deferiprone (DFP), deferasirox (DSX), ciclopirox olamine and lactoferrin (LF) were paired with the antifungal agents amphotericin B (AmB), fluconazole, itraconazole, voriconazole and caspofungin. All chelators except for DFO increased the efficacy of AmB, and significant synergy was seen between AmB and LF for all Cryptococcus strains. Addition of exogenous iron rescued cells from the antifungal effect of LF alone but could not prevent inhibition by AmB + LF, indicating that synergy was not due primarily to iron chelation but to other properties of LF that were potentiated in the presence of AmB. Significant synergy was not seen consistently for other antifungal-chelator combinations, and EDTA, DSX and DFP antagonised the activity of azole drugs in strains of Cryptococcus neoformans var. grubii. This study highlights the range of interactions that can be induced by chelators and indicates that most antifungal drugs are not enhanced by iron limitation in Cryptococcus. Copyright © 2016 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.

Metal chelates of phosphonate-containing ligands-III Analytical applications of N,N,N',N'-ethylenediaminetetra(methylenephosphonic) acid.

PubMed

Zaki, M T; Rizkalla, E N

1980-05-01

N,N*,N',N'-Ethylenediaminetetra(methylenephosphonic) acid is used as a titrant for the direct determination of Cu, Co and Ni, with murexide as indicator. Indirect titrimetric procedures are suggested for the determination of silver, mercury, zinc and cyanide and both direct and indirect methods are applied for the analysis of binary mixtures of silver (or mercury) and copper (cobalt or nickel). The stoichiometry of the reaction, interferences of some metal ions and the pH effects on the complexation reactions are discussed. The values of the equilibrium constants of the protonated CuH(n)L (n = 1, 2, 3 and 4) as well as the unprotonated CuL chelates have been measured.

Efficient removal of heavy metal ions from aqueous solution using salicylic acid type chelate adsorbent.

PubMed

An, Fuqiang; Gao, Baojiao; Dai, Xin; Wang, Min; Wang, Xiaohua

2011-09-15

In this study, 5-aminosalicylic acid was successfully grafted onto the poly(glycidyl methacrylate) (PGMA) macromolecular chains of PGMA/SiO(2) to obtain a novel adsorbent designated as ASA-PGMA/SiO(2). The adsorption properties of ASA-PGMA/SiO(2) for heavy metal ions were studied through batch and column methods. The experimental results showed that ASA-PGMA/SiO(2) possesses strong chelating adsorption ability for heavy metal ions, and its adsorption capacity for Cu(2+), Cd(2+), Zn(2+), and Pb(2+) reaches 0.42, 0.40, 0.35, and 0.31 mmol g(-1), respectively. In addition, pH has a great influence on the adsorption capacity in the studied pH range. The adsorption isotherm data greatly obey the Langmuir and Freundlich model. The desorption of metal ions from ASA-PGMA/SiO(2) is effective using 0.1 mol l(-1) of hydrochloric acid solution as eluent. Consecutive adsorption-desorption experiments showed that ASA-PGMA/SiO(2) could be reused almost without any loss in the adsorption capacity. Copyright © 2011 Elsevier B.V. All rights reserved.

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

PubMed Central

Avila, Maria D.; 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% reduction in a combined primary endpoint of death, MI, stroke, coronary revascularization, or hospitalization for angina. In diabetic patients the benefit was more extreme, with a 41% relative reduction in risk (P = 0.0002) and a 43% reduction in total mortality (P = 0.011). Safety data were favorable. A reduction of oxidative stress by chelation of toxic metals has been proposed as a possible mechanism of action. Summary Recent research suggests that EDTA chelation may be a well-tolerated and effective treatment for post-MI patients. Future replication and mechanistic studies are important prior to implementation in all post-MI patients. PMID:25023079

Comparison of the antibacterial activity of chelating agents using the agar diffusion method

USDA-ARS?s Scientific Manuscript database

The agar diffusion assay was used to examine antibacterial activity of 2 metal chelators. Concentrations of 0 to 40 mM of ethylenediaminetetraacetic acid (EDTA) and ethylenediamine-N,N’-disuccinic acid (EDDS) were prepared in 1.0 M potassium hydroxide (KOH). The pH of the solutions was adjusted to 1...

New detoxification processes for asbestos fibers in the environment.

PubMed

Turci, Francesco; Colonna, Massimiliano; Tomatis, Maura; Mantegna, Stefano; Cravotto, Giancarlo; Fubini, Bice

2010-01-01

Airborne asbestos fibers are associated with many serious detrimental effects on human health, while the hazard posed by waterborne fibers remains an object of debate. In adopting a precautionary principle, asbestos content in water needs to be kept as low as possible and polluting waters with asbestos should be avoided. Turci et al. (2008) recently reported a method for the decontamination of asbestos-polluted waters or landfill leachates from chrysotile that combines power ultrasound (US) with oxalic acid (Ox), an acidic chelating molecule. In the previous study, the occurrence of antigorite, a polymorph of serpentine, the mineral group encompassing chrysotile asbestos, acted as a confounding factor for complete removal of chrysotile from water. The effects of US + Ox on pure chrysotile asbestos from Val Malenco, Italian Central Alps, were examined in this investigation. In the absence of mineral contaminants, a more rapid removal of pure chrysotile from water was undertaken with respect to the previous specimen. After only 12 h of combined US + Ox acid treatment, imaging (SEM) of mineral debris indicated complete loss of fibrous habit. In addition, crystallography and vibrational features of chrysotile were not detectable (x-ray powder diffraction [XRPD] and micro-Raman spectroscopy) and elemental analysis showed a low Mg/Si ratio, i.e., the loss of the brucitic layer in chrysotile (x-ray fluorescence, XRF). Some nanometric rod-shaped debris, observed in the previous study and tentatively recognized as serpentine antigorite, was now found to be made of amorphous silica, which is relatively safe and noncarcinogenic to humans, providing further assurance regarding the safety of treated product. Thus, data indicated the proposed method was effective in detoxifying waterborne chrysotile asbestos fibers.

Thermodynamic stability and relaxation studies of small, triaza-macrocyclic Mn(II) chelates.

PubMed

de Sá, Arsénio; Bonnet, Célia S; Geraldes, Carlos F G C; Tóth, Éva; Ferreira, Paula M T; André, João P

2013-04-07

Due to its favorable relaxometric properties, Mn(2+) is an appealing metal ion for magnetic resonance imaging (MRI) contrast agents. This paper reports the synthesis and characterization of three new triazadicarboxylate-type ligands and their Mn(2+) chelates (NODAHep, 1,4,7-triazacyclononane-1,4-diacetate-7-heptanil; NODABA, 1,4,7-triazacyclononane-1,4-diacetate-7-benzoic acid; and NODAHA, 1,4,7-triazacyclononane-1,4-diacetate-7-hexanoic acid). The protonation constants of the ligands and the stability constants of the chelates formed with Mn(2+) and the endogenous Zn(2+) ion have been determined by potentiometry. In overall, the thermodynamic stability of the chelates is lower than that of the corresponding NOTA analogues (NOTA = 1,4,7-triazacyclononane-1,4,7-triacetate), consistent with the decreased number of coordinating carboxylate groups. Variable temperature (1)H NMRD and (17)O NMR measurements have been performed on the paramagnetic chelates to provide information on the water exchange rates and the rotational dynamics. The values of the (17)O chemical shifts are consistent with the presence of one water molecule in the first coordination sphere of Mn(2+). The three complexes are in the slow to intermediate regime for the water exchange rate, and they all display relatively high rotational correlation times, which explain the relaxivity values between 4.7 and 5.8 mM(-1) s(-1) (20 MHz and 298 K). These relaxivities are higher than expected for Mn(2+) chelates of such size and comparable to those of small monohydrated Gd(3+) complexes. The amphiphilic [Mn(NODAHep)] forms micelles above 22 mM (its critical micellar concentration was determined by relaxometry and fluorescence), and interacts with HSA via its alkylic carbon chain providing a 60% relaxivity increase at 20 MHz due to a longer tumbling time.

Hydroxypyridonate chelating agents and synthesis thereof

DOEpatents

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

1985-11-12

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

Natural chelating agents for radionuclide decorporation

DOEpatents

Premuzic, E.T.

1985-06-11

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

Relationship among chelator adherence, change in chelators, and quality of life in thalassemia.

PubMed

Trachtenberg, Felicia L; Gerstenberger, Eric; Xu, Yan; Mednick, Lauren; Sobota, Amy; Ware, Hannah; Thompson, Alexis A; Neufeld, Ellis J; Yamashita, Robert

2014-10-01

Thalassemia, a chronic blood disease, necessitates life-long adherence to blood transfusions and chelation therapy to reduce iron overload. We examine stability of health-related quality of life (HRQOL) in thalassemia and adherence to chelation therapy over time, especially after changes in chelator choice. Thalassemia Longitudinal Cohort participants in the USA, UK, and Canada completed the SF-36v2 (ages 14+) and the PF-28 CHQ (parents of children <14 years). Chelation adherence was defined as self-reported percent of doses administered in the last 4 weeks. Two hundred and fifty-eight adults/adolescents (mean 29.7 years) and 133 children (mean 8.5 years) completed a mean of 2.8-years follow-up. Children made few chelator changes, whereas a mean of 2.2 changes was observed among the 37% of adults/adolescents who made chelator changes, mainly due to patient preference or medical necessity. Physical HRQOL improved among those with lower iron burden (better health status) at baseline who made a single change in chelator, but declined among participants with multiple changes and/or high iron burden (worse health status). Mental health improved among participants with lower iron burden, but iron overload was negatively associated with social functioning. Adherence did not significantly change over follow-up except for an increase after a change from deferoxamine (DFO) infusion to oral deferasirox (p = 0.03). Predictors of lower adherence for adults/adolescents at follow-up included side effects, smoking, younger age, problems preparing DFO, increased number of days per week DFO prescribed, and lower physical quality of life . Strategies to balance medical needs with family, work, and personal life may assist in adherence.

Preparation and Evaluation of the Chelating Nanocomposite Fabricated with Marine Algae Schizochytrium sp. Protein Hydrolysate and Calcium.

PubMed

Lin, Jiaping; Cai, Xixi; Tang, Mengru; Wang, Shaoyun

2015-11-11

Marine algae have been becoming a popular research topic because of their biological implication. The algae peptide-based metal-chelating complex was investigated in this study. Schizochytrium sp. protein hydrolysate (SPH) possessing high Ca-binding capacity was prepared through stepwise enzymatic hydrolysis to a degree of hydrolysis of 22.46%. The nanocomposites of SPH chelated with calcium ions were fabricated in aqueous solution at pH 6 and 30 °C for 20 min, with the ratio of SPH to calcium 3:1 (w/w). The size distribution showed that the nanocomposite had compact structure with a radius of 68.16 ± 0.50 nm. SPH was rich in acidic amino acids, accounting for 33.55%, which are liable to bind with calcium ions. The molecular mass distribution demonstrated that the molecular mass of SPH was principally concentrated at 180-2000 Da. UV scanning spectroscopy and Fourier transform infrared spectroscopy suggested that the primary sites of calcium-binding corresponded to the carboxyl groups, carbonyl groups, and amino groups of SPH. The results of fluorescent spectroscopy, size distribution, atomic force microscope, and (1)H nuclear magnetic resonance spectroscopy suggested that calcium ions chelated with SPH would cause intramolecular and intermolecular folding and aggregating. The SPH-calcium chelate exerted remarkable stability and absorbability under either acidic or basic conditions, which was in favor of calcium absorption in the gastrointestinal tracts of humans. The investigation suggests that SPH-calcium chelate has the potential prospect to be utilized as a nutraceutical supplement to improve bone health in the human body.

Production of fumaric acid by immobilized Rhizopus arrhizus RH 7-13-9# on loofah fiber in a stirred-tank reactor.

PubMed

Liu, Huan; Zhao, Shijie; Jin, Yuhan; Yue, Xuemin; Deng, Li; Wang, Fang; Tan, Tianwei

2017-11-01

Fumaric acid is an important building-block chemical. The production of fumaric acid by fermentation is possible. Loofah fiber is a natural, biodegradable, renewable polymer material with highly sophisticated and pore structure. This work investigated a new immobilization method using loofah fiber as carrier to produce fumaric acid in a stirred-tank reactor. Compared with other carriers, loofah fiber was proven to be efficiently and successfully used in the reactor. After the optimization process, 20g addition of loofah fiber and 400rpm agitation speed were chosen as the most suitable process conditions. 30.3g/L fumaric acid in the broth as well as 19.16g fumaric acid in the precipitation of solid was achieved, while the yield from glucose reached 0.211g/g. Three batches of fermentation using the same loofah fiber carrier were conducted successfully, which meant it provided a new method to produce fumaric acid in a stirred-tank reactor. Copyright © 2017. Published by Elsevier Ltd.

Gallium(III) chelates of mixed phosphonate-carboxylate triazamacrocyclic ligands relevant to nuclear medicine: Structural, stability and in vivo studies.

PubMed

Prata, Maria I M; André, João P; Kovács, Zoltán; Takács, Anett I; Tircsó, Gyula; Tóth, Imre; Geraldes, Carlos F G C

2017-12-01

Three triaza macrocyclic ligands, H 6 NOTP (1,4,7-triazacyclononane-N,N',N″-trimethylene phosphonic acid), H 4 NO2AP (1,4,7-triazacyclononane-N-methylenephosphonic acid-N',N″-dimethylenecarboxylic acid), and H 5 NOA2P (1,4,7-triazacyclononane-N,N'-bis(methylenephosphonic acid)-N″-methylene carboxylic acid), and their gallium(III) chelates were studied in view of their potential interest as scintigraphic and PET (Positron Emission Tomography) imaging agents. A 1 H, 31 P and 71 Ga multinuclear NMR study gave an insight on the structure, internal dynamics and stability of the chelates in aqueous solution. In particular, the analysis of 71 Ga NMR spectra gave information on the symmetry of the Ga 3+ coordination sphere and the stability of the chelates towards hydrolysis. The 31 P NMR spectra afforded information on the protonation of the non-coordinated oxygen atoms from the pendant phosphonate groups and on the number of species in solution. The 1 H NMR spectra allowed the analysis of the structure and the number of species in solution. 31 P and 1 H NMR titrations combined with potentiometry afforded the measurement of the protonation constants (log K Hi ) and the microscopic protonation scheme of the triaza macrocyclic ligands. The remarkably high thermodynamic stability constant (log K GaL =34.44 (0.04) and stepwise protonation constants of Ga(NOA2P) 2- were determined by potentiometry and 69 Ga and 31 P NMR titrations. Biodistribution and gamma imaging studies have been performed on Wistar rats using the radiolabeled 67 Ga(NO2AP) - and 67 Ga(NOA2P) 2- chelates, having both demonstrated to have renal excretion. The correlation of the molecular properties of the chelates with their pharmacokinetic properties has been analysed. Copyright © 2017 Elsevier Inc. All rights reserved.

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

NASA Astrophysics Data System (ADS)

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.

Effect of the tether on the Mg(II), Ca(II), Cu(II) and Fe(III) stability constants and pM values of chelating agents related to EDDHA.

PubMed

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

2004-11-07

The effect of the length and the structure of the tether on the chelating ability of EDDHA-like chelates have not been established. In this work, PDDHA (propylenediamine-N,N'-bis(o-hydroxyphenyl)acetic acid), BDDHA (butylenediamine-N,N'-bis(o-hydroxyphenyl)acetic acid) and XDDHA (p-xylylenediamine-N,N'-bis(o-hydroxyphenyl)acetic acid) have been obtained and their chemical behaviour has been studied and compared with that of EDDHA following our methodology. The purity of the chelating agents, and their protonation, Ca(II), Mg(II), Fe(III) and Cu(II) stability constants and pM values have been determined. The stability constants and pM values indicate that EDDHA forms the most stable chelates followed by PDDHA. However, the differences among the pFe values are small when a nutrient solution is used, and in these conditions the XDDHA/Fe(III) chelate is the most stable. The results obtained in this work indicate that all the chelating agents studied can be used as iron chlorosis correctors and they can be applied to soil/plant systems.

Facile deferration of commercial fertilizers containing iron chelates for their NMR analysis.

PubMed

Laghi, Luca; Alcañiz, Sara; Cerdán, Mar; Gomez-Gallego, Mar; Sierra, Miguel Angel; Placucci, Giuseppe; Cremonini, Mauro Andrea

2009-06-24

Ethylenediamine-N,N'-bis(o-hydroxyphenylacetic) acid (o,o-EDDHA) is widely used in commercial formulations as a Fe(3+) chelating agent to remedy iron shortage in calcareous and alkaline soils. Commercially available o,o-EDDHA-Fe(3+) formulations contain a mixture of EDDHA regioisomers (o,p-EDDHA and p,p-EDDHA), together with other, still uncharacterized, products. NMR spectroscopy can be applied to their study as long as iron is accurately removed prior to the observation. This paper shows that it is possible to obtain a deferrated solution of the organic ligands present in commercial fertilizers containing the EDDHA-Fe(3+) chelate by treating the chelate with ferrocyanide, thus forming Prussian Blue that can be easily removed by centrifugation. This iron removal process does not cause significant losses of the o,o-EDDHA ligand or its minor structural isomers.

Deaths associated with hypocalcemia from chelation therapy--Texas, Pennsylvania, and Oregon, 2003-2005.

PubMed

2006-03-03

Chelating agents bind lead in soft tissues and are used in the treatment of lead poisoning to enhance urinary and biliary excretion of lead, thus decreasing total lead levels in the body. During the past 30 years, environmental and dietary exposures to lead have decreased substantially, resulting in a considerable decrease in population blood lead levels (BLLs) and a corresponding decrease in the number of patients requiring chelation therapy. Chelating agents also increase excretion of other heavy metals and minerals, such as zinc and, in certain cases, calcium. This report describes three deaths associated with chelation-therapy--related hypocalcemia that resulted in cardiac arrest. Several drugs are used in the treatment of lead poisoning, including edetate disodium calcium (CaEDTA), dimercaperol (British anti-Lewisite), D-penicillamine, and meso-2,3-dimercaptosuccinic acid (succimer). Health-care providers who are unfamiliar with chelating agents and are considering this treatment for lead poisoning should consult an expert in the chemotherapy of lead poisoning. Hospital pharmacies should evaluate whether continued stocking of Na2EDTA is necessary, given the established risk for hypocalcemia, the availability of less toxic alternatives, and an ongoing safety review by the Food and Drug Administration (FDA). Health-care providers and pharmacists should ensure that Na2EDTA is not administered to children during chelation therapy.

Preparation of long alumina fibers by sol-gel method using tartaric acid

NASA Astrophysics Data System (ADS)

Tan, Hong-Bin

2011-12-01

Long alumina fibers were prepared by sol-gel method. The spinning sol was obtained by mixing aluminum nitrate, tartaric acid, and polyvinylpyrrolidone with a mass ratio of 10:3:1.5. Thermogravimetry-differential scanning calorimetry (TG-DSC), Fourier transform infrared (FT-IR) spectra, X-ray diffraction (XRD), and scanning electron microscopy (SEM) were used to characterize the properties of the gel and ceramic fibers. A little of α-Al2O3 phase is observed in the alumina precursor gel fibers sintered at 1273 K. The fibers with a uniform diameter can be obtained when sintered at 1473 K, and its main phase is also indentified as α-Al2O3.

[Enhanced Phytoextraction of Heavy Metals from Contaminated Soils Using Sedum alfredii Hance with Biodegradable Chelate GLDA].

PubMed

Wei, Ze-bin; Chen, Xiao-hong; Wu, Qi-tang; Tan, Meng

2015-05-01

Chemically enhanced phytoextraction by hyperaccumulator has been proposed as an effective approach to remove heavy metals from contaminated soil. Pot experiment was conducted to investigate the effect of application of the biodegradable chelate GLDA (L glutamic acid N,N-diacetic acid) at different doses or the combination of GLDA with EDTA (ethylenediamine tetraacetic acid) or CIT (citric acid) on the uptake of Cd, Zn and Pb by Sedum alfredii Hance (a Zn and Cd hyperaccumulator). Experimental results showed that GLDA addition to soil significantly increased the concentrations of Cd and Zn in Sedum alfredii Hance and its Cd and Zn phytoextraction compared to the control. Additionally, GLDA at 2.5 mmol · kg(-1) resulted in the highest phytoextraction, being 2.5 and 2.6 folds of the control for Cd and Zn, respectively. However, the combined application of GLDA + EDTA (1:1) and GLDA + CIT (1 :1 and 1:3) at a total dose of 5 mmol · kg(-1) did not increase the phytoextraction of Zn and Cd, compared to the GLDA only treatment. Therefore, the biodegradable chelate GLDA could be regarded as a good chelate candidate for the phytoextraction of heavy metals of heavy metals from contaminated soils, particularly for Cd and Zn contaminated soils.

Liquid droplet sensing using twisted optical fiber couplers fabricated by hydrofluoric acid flow etching

NASA Astrophysics Data System (ADS)

Son, Gyeongho; Jung, Youngho; Yu, Kyoungsik

2017-04-01

We report a directional-coupler-based refractive index sensor and its cost-effective fabrication method using hydrofluoric acid droplet wet-etching and surface-tension-driven liquid flows. The proposed fiber sensor consists of a pair of twisted tapered optical fibers with low excess losses. The fiber cores in the etched microfiber region are exposed to the surrounding medium for efficient interaction with the guided light. We observe that the etching-based low-loss fiber-optic sensors can measure the water droplet volume by detecting the refractive index changes of the surrounding medium around the etched fiber core region.

Effect of endodontic chelating solutions on the bond strength of endodontic sealers.

PubMed

Tuncel, Behram; Nagas, Emre; Cehreli, Zafer; Uyanik, Ozgur; Vallittu, Pekka; Lassila, Lippo

2015-01-01

The purpose of this in vitro study was to evaluate the effect of various chelating solutions on the radicular push-out bond strength of calcium silicate-based and resin-based root canal sealers. Root canals of freshly-extracted single-rooted teeth (n = 80) were instrumented by using rotary instruments. The specimens were randomly divided into 4 groups according to the chelating solutions being tested: (1) 17% ethylenediaminetetraacetic acid (EDTA); (2) 9% etidronic acid; (3) 1% peracetic acid (PAA); and (4) distilled water (control). In each group, the roots were further assigned into 2 subgroups according to the sealer used: (1) an epoxy resin-based sealer (AH Plus) and (2) a calcium silicate-based sealer (iRoot SP). Four 1 mm-thick sections were obtained from the coronal aspect of each root (n = 40 slices/group). Push-out bond strength test was performed at a crosshead speed of 1 mm/min., and the bond strength data were analyzed statistically with two-way analysis of variance (ANOVA) with Bonferroni's post hoc test (p < 0.05). Failure modes were assessed quantitatively under a stereomicroscope. Irrespective of the irrigation regimens, iRoot SP exhibited significantly higher push-out bond strength values than AH Plus (p < 0.05). For both the sealers, the use of chelating solutions increased the bond strength, but to levels that were not significantly greater than their respective controls (p > 0.05). iRoot SP showed higher resistance to dislocation than AH Plus. Final irrigation with 17% EDTA, 9% Etidronic acid, and 1% PAA did not improve the bond strength of AH Plus and iRoot SP to radicular dentin.

Heavy metal displacement in chelate-irrigated soil during phytoremediation

NASA Astrophysics Data System (ADS)

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.

Removal of cadmium from fish sauce using chelate resin.

PubMed

Sasaki, Tetsuya; Araki, Ryohei; Michihata, Toshihide; Kozawa, Miyuki; Tokuda, Koji; Koyanagi, Takashi; Enomoto, Toshiki

2015-04-15

Fish sauce that is prepared from squid organs contains cadmium (Cd), which may be present at hazardous concentrations. Cd molecules are predominantly protein bound in freshly manufactured fish sauce, but are present in a liberated form in air-exposed fish sauce. In the present study, we developed a new method for removing both Cd forms from fish sauce using chelate resin and a previously reported tannin treatment. Sixteen-fold decreases in Cd concentrations were observed (0.78-0.05 mg/100 mL) following the removal of liberated Cd using chelate resin treatment, and the removal of protein-bound Cd using tannin treatment. Major nutritional components of fish sauce were maintained, including free amino acids and peptides, and angiotensin I-converting enzyme inhibitory and antioxidant activities. Copyright © 2014 Elsevier Ltd. All rights reserved.

Enzyme immobilization on ultrafine cellulose fibers via poly(acrylic acid) electrolyte grafts.

PubMed

Chen, Hong; Hsieh, You-Lo

2005-05-20

Ultrafine cellulose fiber (diameter 200-400 nm) surfaces were grafted with polyacrylic acid (PAA) via either ceric ion initiated polymerization or methacrylation of cellulose with methacrylate chloride (MACl) and subsequent free-radical polymerization of acrylic acid. PAA grafts by ceric ion initiated polymerization increased with increasing reaction time (2-24 h), monomer (0.3-2.4 M), and initiator (1-10 mM) concentrations, and spanned a broad range from 5.5-850%. PAA grafts on the methacrylated cellulose fibers also increased with increasing molar ratios of MACl to cellulosic hydroxyl groups (MACl/OH, 2-6.4) and monomer acrylic acid (AA) to initiator potassium persulfate (KPS) ratios ([AA]/[KPS], 1.5-6), and were in a much narrower range between 12.8% and 29.4%. The adsorption of lipase (at 1 mg/ml lipase and pH 7) and the activity of adsorbed lipase (pH 8.5, 30 degrees C), in both cases decreased with increasing PAA grafts. The highest adsorption and activity of the lipase on the ceric ion initiated grafted fibers were 1.28 g/g PAA and 4.3 U/mg lipase, respectively, at the lowest grafting level of 5.5% PAA, whereas they were 0.33 g/g PAA and 7.1 U/mg lipase, respectively, at 12.8% PAA grafts on the methacrylated and grafted fibers. The properties of the grafted fibers and the absorption behavior and activity of lipase suggest that the PAA grafts are gel-like by ceric-initiated reaction and brush-like by methacrylation and polymerization. The adsorbed lipase on the ceric ion-initiated grafted surface possessed greatly improved organic solvent stability over the crude lipase. The adsorbed lipases exhibited 0.5 and 0.3 of the initial activity in the second and third assay cycles, respectively. (c) 2004 Wiley Periodicals, Inc.

Natural chelates for radionuclide decorporation

DOEpatents

Premuzic, E.T.

1983-08-25

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

Hyaluronic acid-modified manganese-chelated dendrimer-entrapped gold nanoparticles for the targeted CT/MR dual-mode imaging of hepatocellular carcinoma

NASA Astrophysics Data System (ADS)

Wang, Ruizhi; Luo, Yu; Yang, Shuohui; Lin, Jiang; Gao, Dongmei; Zhao, Yan; Liu, Jinguo; Shi, Xiangyang; Wang, Xiaolin

2016-09-01

Hepatocellular carcinoma (HCC) is the most common malignant tumor of the liver. The early and effective diagnosis has always been desired. Herein, we present the preparation and characterization of hyaluronic acid (HA)-modified, multifunctional nanoparticles (NPs) targeting CD44 receptor-expressing cancer cells for computed tomography (CT)/magnetic resonance (MR) dual-mode imaging. We first modified amine-terminated generation 5 poly(amidoamine) dendrimers (G5.NH2) with an Mn chelator, 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA), fluorescein isothiocyanate (FI), and HA. Then, gold nanoparticles (AuNPs) were entrapped within the above raw product, denoted as G5.NH2-FI-DOTA-HA. The designed multifunctional NPs were formed after further Mn chelation and purification and were denoted as {(Au0)100G5.NH2-FI-DOTA(Mn)-HA}. These NPs were characterized via several different techniques. We found that the {(Au0)100G5.NH2-FI-DOTA(Mn)-HA} NPs exhibited good water dispersibility, stability under different conditions, and cytocompatibility within a given concentration range. Because both AuNPs and Mn were present in the product, {(Au0)100G5.NH2-FI-DOTA(Mn)-HA} displayed a high X-ray attenuation intensity and favorable r1 relaxivity, which are advantageous properties for targeted CT/MR dual-mode imaging. This approach was used to image HCC cells in vitro and orthotopically transplanted HCC tumors in a unique in vivo model through the CD44 receptor-mediated endocytosis pathway. This work introduces a novel strategy for preparing multifunctional NPs via dendrimer nanotechnology.

Muscle Fiber Characteristics and Fatty Acid Compositions of the Four Major Muscles in Korean Native Black Goat.

PubMed

Hwang, Young-Hwa; Joo, Sung-Hyun; Bakhsh, Allah; Ismail, Ishamri; Joo, Seon-Tea

2017-01-01

The objective of this study was to investigate the relationship between muscle fiber characteristics and fatty acid composition of four major muscles in Korean native black goat (KNBG). Longissimus lumborum (LL), psoas major (PM), semimembranosus (SM), and gluteus medius (GM) were obtained from five male KNBGs of 36 mon of age and subjected to histochemical analysis and to determine fatty acid composition and meat quality traits. There were significant ( p <0.05) differences in fiber number percentage (FNP) and fiber area percentage (FAP) of fiber types among these four muscles. PM had the highest FNP of type I and the lowest FNP of type IIB, while SM had the highest FNP of type IIB. The highest fat content was observed in LL while SM had the lowest fat content. The proportions of SFA and MUFA were significantly ( p <0.05) different among four muscles due to differences in the majority of fatty acids such as oleic (C18:1) and palmitic (C16:0) acids. The PUFA/SFA ratio was significantly ( p <0.05) different among four muscles, and the highest PUFA/SFA ratio was observed in PM. Results suggested that LL and PM might be healthful because of higher desirable fatty acid value and PUFA/SFA ratio, respectively. Also, data showed that correlations between muscle fiber types and fatty acids proportion of goat muscles were reversed with those of cattle muscles.

Metal chelate affinity precipitation of RNA and purification of plasmid DNA

NASA Technical Reports Server (NTRS)

Balan, Sindhu; Murphy, Jason; Galaev, Igor; Kumar, Ashok; Fox, George E.; Mattiasson, Bo; Willson, Richard C.

2003-01-01

The affinity of metal chelates for amino acids, such as histidine, is widely used in purifying proteins, most notably through six-histidine 'tails'. We have found that metal affinity interactions can also be applied to separation of single-stranded nucleic acids through interactions involving exposed purines. Here we describe a metal affinity precipitation method to resolve RNA from linear and plasmid DNA. A copper-charged copolymer of N-isopropyl acrylamide (NIPAM) and vinyl imidazole (VI) is used to purify plasmid from an alkaline lysate of E. coli. The NIPAM units confer reversible solubility on the copolymer while the imidazole chelates metal ions in a manner accessible to interaction with soluble ligands. RNA was separated from the plasmid by precipitation along with the polymer in the presence of 800 mM NaCl. Bound RNA could be recovered by elution with imidazole and separated from copolymer by a second precipitation step. RNA binding showed a strong dependence on temperature and on the type of buffer used.

Ironing iron out in Parkinson's disease and other neurodegenerative diseases with iron chelators: a lesson from 6-hydroxydopamine and iron chelators, desferal and VK-28.

PubMed

Youdim, Moussa B H; Stephenson, Galia; Ben Shachar, Dorit

2004-03-01

In Parkinson's disease (PD) and its neurotoxin-induced models, 6-hydroxydopamine (6-OHDA) and N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), significant accumulation of iron occurs in the substantia nigra pars compacta. The iron is thought to be in a labile pool, unbound to ferritin, and is thought to have a pivotal role to induce oxidative stress-dependent neurodegeneration of dopamine neurons via Fenton chemistry. The consequence of this is its interaction with H(2)O(2) to generate the most reactive radical oxygen species, the hydroxyl radical. This scenario is supported by studies in both human and neurotoxin-induced parkinsonism showing that disposition of H(2)O(2) is compromised via depletion of glutathione (GSH), the rate-limiting cofactor of glutathione peroxide, the major enzyme source to dispose H(2)O(2) as water in the brain. Further, radical scavengers have been shown to prevent the neurotoxic action of the above neurotoxins and depletion of GSH. However, our group was the first to demonstrate that the prototype iron chelator, desferal, is a potent neuroprotective agent in the 6-OHDA model. We have extended these studies and examined the neuroprotective effect of intracerebraventricular (ICV) pretreatment with the prototype iron chelator, desferal (1.3, 13, 134 mg), on ICV induced 6-OHDA (250 micro g) lesion of striatal dopamine neurons. Desferal alone at the doses studied did not affect striatal tyrosine hydroxylase (TH) activity or dopamine (DA) metabolism. All three pretreatment (30 min) doses of desferal prevented the fall in striatal and frontal cortex DA, dihydroxyphenylacetic acid, and homovalinic acid, as well as the left and right striatum TH activity and DA turnover resulting from 6-OHDA lesion of dopaminergic neurons. A concentration bell-shaped neuroprotective effect of desferal was observed in the striatum, with 13 micro g being the most effective. Neither desferal nor 6-OHDA affected striatal serotonin, 5-hydroxyindole acetic acid, or

Zinc chelation with hydroxamate in histone deacetylases modulated by water access to the linker binding channel.

PubMed

Wu, Ruibo; Lu, Zhenyu; Cao, Zexing; Zhang, Yingkai

2011-04-27

It is of significant biological interest and medical importance to develop class- and isoform-selective histone deacetylase (HDAC) modulators. The impact of the linker component on HDAC inhibition specificity has been revealed but is not understood. Using Born-Oppenheimer ab initio QM/MM MD simulations, a state-of-the-art approach to simulating metallo-enzymes, we have found that the hydroxamic acid remains to be protonated upon its binding to HDAC8, and thus disproved the mechanistic hypothesis that the distinct zinc-hydroxamate chelation modes between two HDAC subclasses come from different protonation states of the hydroxamic acid. Instead, our simulations suggest a novel mechanism in which the chelation mode of hydroxamate with the zinc ion in HDACs is modulated by water access to the linker binding channel. This new insight into the interplay between the linker binding and the zinc chelation emphasizes its importance and gives guidance regarding linker design for the development of new class-IIa-specific HDAC inhibitors.

Enhancement of 5-aminolevulinic acid-based fluorescence detection of side population-defined glioma stem cells by iron chelation

PubMed Central

Wang, Wenqian; Tabu, Kouichi; Hagiya, Yuichiro; Sugiyama, Yuta; Kokubu, Yasuhiro; Murota, Yoshitaka; Ogura, Shun-ichiro; Taga, Tetsuya

2017-01-01

Cancer stem cells (CSCs) are dominantly responsible for tumor progression and chemo/radio-resistance, resulting in tumor recurrence. 5-aminolevulinic acid (ALA) is metabolized to fluorescent protoporphyrin IX (PpIX) specifically in tumor cells, and therefore clinically used as a reagent for photodynamic diagnosis (PDD) and therapy (PDT) of cancers including gliomas. However, it remains to be clarified whether this method could be effective for CSC detection. Here, using flow cytometry-based analysis, we show that side population (SP)-defined C6 glioma CSCs (GSCs) displayed much less 5-ALA-derived PpIX fluorescence than non-GSCs. Among the C6 GSCs, cells with ultralow PpIX fluorescence exhibited dramatically higher tumorigenicity when transplanted into the immune-deficient mouse brain. We further demonstrated that the low PpIX accumulation in the C6 GSCs was enhanced by deferoxamine (DFO)-mediated iron chelation, not by reserpine-mediated inhibition of PpIX-effluxing ABCG2. Finally, we found that the expression level of the gene for heme oxygenase-1 (HO-1), a heme degradation enzyme, was high in C6 GSCs, which was further up-regulated when treated with 5-ALA. Our results provide important new insights into 5-ALA-based PDD of gliomas, particularly photodetection of SP-defined GSCs by iron chelation based on their ALA-PpIX-Heme metabolism. PMID:28169355

The influence of chemical surface modification of kenaf fiber using hydrogen peroxide on the mechanical properties of biodegradable kenaf fiber/poly(lactic acid) composites.

PubMed

Razak, Nur Inani Abdul; Ibrahim, Nor Azowa; Zainuddin, Norhazlin; Rayung, Marwah; Saad, Wan Zuhainis

2014-03-07

Bleaching treatment of kenaf fiber was performed in alkaline medium containing hydrogen peroxide solution maintained at pH 11 and 80 °C for 60 min. The bleached kenaf fiber was analyzed using Fourier Transform Infrared (FTIR) and X-ray Diffraction (XRD) analysis. The bleached kenaf fiber was then compounded with poly-(lactic acid) (PLA) via a melt blending method. The mechanical (tensile, flexural and impact) performance of the product was tested. The fiber treatment improved the mechanical properties of PLA/bleached kenaf fiber composites. Scanning electron micrograph (SEM) morphological analysis showed improvement of the interfacial adhesion between the fiber surface and polymer matrix.

Effect of chelators and nisin produced in situ on inhibition and inactivation of gram negatives.

PubMed

Boziaris, I S; Adams, M R

1999-12-15

The ability of chelators and nisin generated in situ to inhibit and inactivate E. coli and other gram negatives in a model substrate was investigated. The effect of various chelators and different concentrations of exogenous nisin on inhibition of E. coli in broth medium showed that only EDTA and pyrophosphates were able to cause appreciable inhibition of E. coli by nisin. In a broth where L. lactis NCFB 497 produced nisin in a concentration of 250-300 IU/ml, pyrophosphates were unable to inactivate E. coli. Under the same conditions, addition of EDTA led to inactivation of E. coli at neutral and slightly acidic pH only. A cocktail of strains of E. coli was less sensitive than E. coli ATCC 25922 alone. Pseudomonas aeruginosa was more sensitive and salmonellae more resistant. EDTA also caused a slight reduction in the L. lactis population and its biochemical activity as regards pH drop and acid production. Some of the inhibition of E. coli could be ascribed to the physical presence of Lactococcus cells rather than their metabolites excreted into the medium. Failure to observe any inhibition in fermented broths at their natural pH (4.0) was ascribed to the poor chelating power of EDTA under acid conditions.

Luminescent lanthanide chelates and methods of use

DOEpatents

Selvin, Paul R.; Hearst, John

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.

Technical note: improved methodology for analyses of acid detergent fiber and acid detergent lignin.

PubMed

Raffrenato, E; Van Amburgh, M E

2011-07-01

The objective of this study was to evaluate the methodology of the acid detergent lignin (ADL) assay in an effort to evaluate particle loss, improve repeatability, and decrease variation within and among samples. The original ADL method relied on asbestos as a filtering aid, but that was removed in 1989 with the mandate from the Environmental Protection Agency to eliminate asbestos in the environment. Furthermore, recent work on fiber methodology indicated that pore size in the Gooch sintered glass crucible (40-60 μm) was too large to trap all of the small particles associated with neutral detergent fiber (NDF) and acid detergent fiber (ADF). Thus, any loss of ADF could potentially result in a loss of ADL. Sixty forages including conventional and brown midrib corn silages, alfalfa silages and hays, mature grasses, early vegetative grasses, and 9 feces samples, were analyzed sequentially for ADF and ADL as outlined in the 1973 procedure of Van Soest except for the use of the asbestos fiber. A glass microfiber filter with a 1.5-μm pore size was chosen as a filtering aid because it met the criteria required by the assay: glass, heat resistant, acid resistant, chemically inert, and hydrophobic. To compare with the current ADF and ADL assays, the assays were conducted with either no filter or the glass filter inserted into crucibles, rinsed with acetone, and then according to the 1973 procedure of Van Soest. The samples analyzed covered a range from 18.11 to 55.79% ADF and from 0.96 to 9.94% ADL on a dry matter (DM) basis. With the use of the filter, the mean ADF values increased 4.2% and mean ADL values increased 18.9%. Overall, both ADF and ADL values were greater with the use of the glass microfiber filter than without, indicating that as the type of sample analyzed changed, use of the Gooch crucible without the filtering aid results in particle loss. The adoption of the use of a small pore size (1.5 μm) glass microfiber filter to improve filtration and recovery

The Chelate Effect Redefined.

ERIC Educational Resources Information Center

da Silva, J. J. R. Frausto

1983-01-01

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

EFFECT OF CHELATING AGENTS ON UPTAKE OF Ca$sup 45$ AND Sr$sup 85$ BY DEFATTED BONE IN VITRO

DOE Office of Scientific and Technical Information (OSTI.GOV)

Samachson, J.; Lederer, H.

The presence of chelating agents in buffered solutions affected the relative uptake of Ca/sup 45/ and Sr/sup 85/ by defatted bone powder. Strong chelating agents, like ethylenediaminetetraacetic acid and cyclohexanediaminetetraacetic acid, decreased the ratio of Ca/sup 45//Sr/sup 85/ uptake considerably in presence of Ca, Ca plus Sr, or Sr carrier. Citrate and adenosinetriphosphate had similar but weaker effects. No effect was shown by glucose, lactate, gluconate, bicarbonate, bicarbonate plus phosphate, glutamate, aspartate, borate, glycerophosphate, lysine or glutathione. Those compeunds which showed no effect had stability constants for Ca of less than 3. Strong chelating agents also decreased the relative amountmore » of Sr/sup 85/ removed from defatted bone powder by exchange. Results indicate that natural chelating agents may be partly responsible for the low Ca/sup 45//Sr/sup 85/ uptake ratio by bone from serum compared with uptake from synthetic inorganic solutions and emphasize the difficulty of removing be partly responsible for the low Ca/sup 45//Sr/sup 85/ uptske ratio by bone from serum compared with uptake from synthetic inorganic solutions and emphasize the difficulty of removing Sr/sup 35/ from bone with chelating agents now available. (auth)« less

Micronutrient metal speciation is driven by competitive organic chelation in grassland soils.

NASA Astrophysics Data System (ADS)

Boiteau, R.; Shaw, J. B.; Paša-Tolić, L.; Koppenaal, D.; Jansson, J.

2017-12-01

Many elements are scarcely soluble in aqueous conditions found in high pH environments, such as calcareous grassland soils, unless complexed to strong binding organic ligands. To overcome this limitation, some plants and microbes produce chelators that solubilize micronutrient metals such as Fe, Ni, Cu, and Zn from mineral phases. These complexes are taken up by organisms via specific membrane receptors, thereby differentially impacting the bioavailability of these metals to the plant and microbial community. Although the importance of these chelation strategies for individual organisms has been well established, little is known about which pathways coexist within rhizosphere microbiomes or how they interact and compete for metal binding. Identifying these metallo-organic species within natural ecosystems has remained a formidable analytical challenge due to the vast diversity of compounds and poorly defined metabolic processes in complex soil matrix. Herein, we employed recently developed liquid chromatography (LC) mass spectrometry (MS) methods to characterize the speciation of water-soluble dissolved trace elements (Fe, Ni, Cu, and Zn) from Kansas Prairie soil. Both plant and fungal chelators were identified, revealing compound-specific patterns of chelation to biologically essential metals. Numerous metabolites typically implicated in plant iron acquisition and homeostasis, including mugineic acids, deoxymugineic acid, nicotianamine, and hydroxynicotianamine, dominated the speciation of divalent metals such as Ni, Cu, and Zn (2-57 pmol / g soil). In contrast, the fungal siderophore ferricrocine bound comparatively more trivalent Fe (9pmol / g soil). These results define biochemical pathways that underpin the regulation of metals in the grassland rhizosphere. They also raise new questions about the competition of these compounds for metal binding and their bioavailability to different members of the rhizosphere population.

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

PubMed

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.

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

PubMed Central

Miller, Gloria; Begonia, Gregorio; Begonia, Maria; Ntoni, Jennifer; Hundley, Oscar

2008-01-01

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 with the metal) or

Plant-derived phenolic compounds prevent the DNA single-strand breakage and cytotoxicity induced by tert-butylhydroperoxide via an iron-chelating mechanism.

PubMed Central

Sestili, Piero; Diamantini, Giuseppe; Bedini, Annalida; Cerioni, Liana; Tommasini, Ilaria; Tarzia, Giorgio; Cantoni, Orazio

2002-01-01

The protective effects of selected members from a series of caffeic acid esters and flavonoids were tested in various toxicity paradigms using U937 cells, previously shown to be sensitive to either iron chelators or bona fide radical scavengers or to both classes of compounds. It was found that all the protective polyphenols were active at very low concentrations and that their effects were observed only under those conditions in which iron chelators also afforded protection. Consistently, active polyphenolic compounds, unlike the inactive ones, effectively chelated iron in an in vitro system. It follows that, at least under the experimental conditions utilized in the present study, the most prominent activity of these polyphenolic compounds resides in their ability to chelate iron. Further studies revealed that the protective effects afforded by the caffeic acid esters and flavonoids were largely mediated by the catechol moiety and that the relative biological potency of these compounds was a direct function of their lipophilicity. PMID:11988084

A comparative study of chelating and cationic ion exchange resins for the removal of palladium(II) complexes from acidic chloride media.

PubMed

Hubicki, Zbigniew; Wołowicz, Anna

2009-05-30

The increasing demand for palladium for technological application requires the development of ion exchange chromatography. Recently ion exchange chromatography has developed largely as a result of new types of ion exchangers available on the market of which two types are widely applied. One of them are selective (chelating) and modified ion exchangers and the other one are liquid exchangers. Two types of ion exchange resins such as chelating (Lewatit TP 214, Purolite S 920) and cationic (Chelite S, Duolite GT 73) ion exchangers are used for the recovery of palladium(II) complexes from chloride media (0.1-2.0M HCl-1.0M NaCl-0.0011 M Pd(II); 0.1-2.0M HCl-2.0M NaCl-0.0011M Pd(II)). The influence of concentration of hydrochloric acid, sodium chloride as well as the phase contact time on the degree of recovery of palladium(II) complexes was studied. Moreover, the amount of palladium(II) chlorocomplexes sorbed onto ion exchangers, the working ion exchange capacities and the weight and bed distribution coefficients were calculated in order to judge which of two types of resins possesses the best performance towards palladium(II) complexes.

Fluoride ion recognition by chelating and cationic boranes.

PubMed

Hudnall, Todd W; Chiu, Ching-Wen; Gabbaï, François P

2009-02-17

Because of the ubiquity of fluoride ions and their potential toxicity at high doses, researchers would like to design receptors that selectively detect this anion. Fluoride is found in drinking water, toothpaste, and osteoporosis drugs. In addition, fluoride ions also can be detected as an indicator of uranium enrichment (via hydrolysis of UF(6)) or of the chemical warfare agent sarin, which releases the ion upon hydrolysis. However, because of its high hydration enthalpy, the fluoride anion is one of the most challenging targets for anion recognition. Among the various recognition strategies that are available, researchers have focused a great deal of attention on Lewis acidic boron compounds. These molecules typically interact with fluoride anions to form the corresponding fluoroborate species. In the case of simple triarylboranes, the fluoroborates are formed in organic solvents but not in water. To overcome this limitation, this Account examines various methods we have pursued to increase the fluoride-binding properties of boron-based receptors. We first considered the use of bifunctional boranes, which chelate the fluoride anion, such as 1,8-diborylnaphthalenes or heteronuclear 1-boryl-8-mercurio-naphthalenes. In these molecules, the neighboring Lewis acidic atoms can cooperatively interact with the anionic guest. Although the fluoride binding constants of the bifunctional compounds exceed those of neutral monofunctional boranes by several orders of magnitude, the incompatibility of these systems with aqueous media limits their utility. More recently, we have examined simple triarylboranes whose ligands are decorated by cationic ammonium or phosphonium groups. These cationic groups increase the electrophilic character of these boranes, and unlike their neutral analogs, they are able to complex fluoride in aqueous media. We have also considered cationic boranes, which form chelate complexes with fluoride anions. Our work demonstrates that Coulombic and chelate

The effect of change in pH on the solubility of iron bis-glycinate chelate and other iron compounds.

PubMed

García-Casal, M N; Layrisse, M

2001-03-01

The effect of a pH change from 2 to 6 was tested on the solubility of ferrous sulfate, ferrous fumarate, iron bis-glycine chelate (Ferrochel) and sodium-iron ethylenediaminetetraacetic acid (NaFeEDTA). It was found that at pH 2 ferrous sulfate, Ferrochel and NaFeEDTA were completely soluble and only 75% of iron from ferrous fumarate was soluble. When pH was raised to 6, iron from amino acid chelate and NaFeEDTA remained completely soluble while solubility from ferrous sulfate and ferrous fumarate decreased 64 and 74%, respectively compared to the amount of iron initially soluble at pH 2. These results suggest that iron solubility from iron bis-glycine chelate and NaFeEDTA is not affected by pH changes within the ranges tested, probably because iron remained associated to the respective compounds.

Chelation in metal intoxication. VIII. Removal of chromium from organs of potassium chromate administered rats.

PubMed

Behari, J R; Tandon, S K

1980-03-01

Some polyaminocarboxylic acids were examined for their ability to mobilize chromium from certain vital organs, their subcellular fractions, and blood cells of potassium chromate administered rats. Hexamethylene 1,6-diamino tetraacetic acid (TDTA), triethylene tetramine hexaacetic acid (TTHA), and ethylene diamine di (O-hydroxylphenyl acetic acid) (EDDHA) may be useful in preventing or reducing chromate toxicity. No definite relationship could be observed between the structure of the chelating agents and their chromium-removing capacity.

Mercury removal in utility wet scrubber using a chelating agent

DOEpatents

Amrhein, Gerald T.

2001-01-01

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

Immobilization of Fe chelators on sepharose gel and its effect on their chemical properties.

PubMed

Yehuda, Zehava; Hadar, Yitzhak; Chen, Yona

2003-09-24

Iron chelates are usually costly and easily leached beyond the root zone. This creates a need to frequently replenish the rhizosphere with chelated Fe and might contaminate groundwater with organic compounds and metals. The development of a slow-release Fe fertilizer that will efficiently supply Fe to plants while exhibiting high resistance toward leaching and/or degradation in the rhizosphere has been the focus of this study. Desferrioxamine B (DFOB) and ethylenediaminebis(o-hydroxyphenylacetic acid) (EDDHA) were immobilized on Sepharose. (13)C NMR and FTIR measurements confirmed that coupling of DFOB to the gel did not appear to influence its ability to chelate Fe(3+) or its binding nature. Isotherms for the immobilized ligands were determined in the presence of 1 mM HEDTA, at 25 degrees C and at an ionic strength of 0.1 M. The isotherms showed a high affinity of Fe(3+) to the ligands and binding up to saturation level throughout the pH range examined (4.0-9.0). The K(app) values for the immobilized Fe chelates were determined using a modified Scatchard model and found to be lower than the soluble ones. This decrease in K(app) might facilitate Fe uptake from these chelates by plants.

Hollow Fiber Supported Liquid Membrane Extraction Combined with HPLC-UV for Simultaneous Preconcentration and Determination of Urinary Hippuric Acid and Mandelic Acid

PubMed Central

Bahrami, Abdulrahman; Ghamari, Farhad; Yamini, Yadollah; Ghorbani Shahna, Farshid; Moghimbeigi, Abbas

2017-01-01

This work describes a new extraction method with hollow-fiber liquid-phase microextraction based on facilitated pH gradient transport for analyzing hippuric acid and mandelic acid in aqueous samples. The factors affecting the metabolites extraction were optimized as follows: the volume of sample solution was 10 mL with pH 2 containing 0.5 mol·L−1 sodium chloride, liquid membrane containing 1-octanol with 20% (w/v) tributyl phosphate as the carrier, the time of extraction was 150 min, and stirring rate was 500 rpm. The organic phase immobilized in the pores of a hollow fiber was back-extracted into 24 µL of a solution containing sodium carbonate with pH 11, which was placed inside the lumen of the fiber. Under optimized conditions, the high enrichment factors of 172 and 195 folds, detection limit of 0.007 and 0.009 µg·mL−1 were obtained. The relative standard deviation (RSD) (%) values for intra- and inter-day precisions were calculated at 2.5%–8.2% and 4.1%–10.7%, respectively. The proposed method was successfully applied to the analysis of these metabolites in real urine samples. The results indicated that hollow-fiber liquid-phase microextraction (HF-LPME) based on facilitated pH gradient transport can be used as a sensitive and effective method for the determination of mandelic acid and hippuric acid in urine specimens. PMID:28208685

Rationale for the Successful Management of EDTA Chelation Therapy in Human Burden by Toxic Metals

PubMed Central

2016-01-01

Exposure to environmental and occupational toxicants is responsible for adverse effects on human health. Chelation therapy is the only procedure able to remove toxic metals from human organs and tissue, aiming to treat damage related to acute and/or chronic intoxication. The present review focuses on the most recent evidence of the successful use of the chelating agent ethylenediaminetetraacetic acid (EDTA). Assessment of toxic-metal presence in humans, as well as the rationale of EDTA therapy in cardiovascular and neurodegenerative diseases, is reported. PMID:27896275

Micronutrient metal speciation is controlled by competitive organic chelation in grassland soils

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boiteau, Rene M.; Shaw, Jared B.; Pasa-Tolic, Ljiljana

Many elements are scarcely soluble in aqueous conditions found in high pH environments, such as calcareous grassland soils, unless complexed to strong binding organic ligands. To overcome this limitation, some plants and microbes produce chelators that solubilize micronutrient metals such as Fe, Ni, Cu, and Zn from mineral phases. These complexes are taken up by organisms via specific membrane receptors, thereby differentially impacting the bioavailability of these metals to the plant and microbial community. Although the importance of these chelation strategies for individual organisms has been well established, little is known about which pathways coexist within rhizosphere microbiomes or howmore » they interact and compete for metal binding. Identifying these metallo-organic species within natural ecosystems has remained a formidable analytical challenge due to the vast diversity of compounds and poorly defined metabolic processes in complex soil matrix. Herein, we employed recently developed liquid chromatography (LC) mass spectrometry (MS) methods to characterize the speciation of water-soluble dissolved trace elements (Fe, Ni, Cu, and Zn) from Kansas Prairie soil. Both plant and fungal chelators were identified, revealing compound-specific patterns of chelation to biologically essential metals. Numerous metabolites typically implicated in plant iron acquisition and homeostasis, including mugineic acids, deoxymugineic acid, nicotianamine, and hydroxynicotianamine, dominated the speciation of divalent metals such as Ni, Cu, and Zn (2-57 pmol / g soil). In contrast, the fungal siderophore ferricrocine bound comparatively more trivalent Fe (9pmol / g soil). These results define biochemical pathways that underpin the regulation of metals in the grassland rhizosphere. They also raise new questions about the competition of these compounds for metal binding and their bioavailability to different members of the rhizosphere population. Even small structural

Properties of electrospun pollock gelatin/poly(vinyl alcohol) and pollock gelatin/poly(lactic acid) fibers

USDA-ARS?s Scientific Manuscript database

Pollock gelatin/poly(vinyl alcohol) (PVA) fibers were electrospun using deionized water as the solvent and pollock gelatin/poly(lactic acid) (PLA) fibers were electrospun using 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) as the solvent. The chemical, thermal, and thermal stability properties were exami...

Iminodiacetic acid modified kenaf fiber for waste water treatment.

PubMed

Razak, Muhammad Raznisyafiq; Yusof, Nor Azah; Haron, Mohammad Jelas; Ibrahim, Norazowa; Mohammad, Faruq; Kamaruzaman, Sazlinda; Al-Lohedan, Hamad A

2018-06-01

In the present study, iminodiacetic acid (IDA)-modified kenaf fiber, K-IDA formed by the chemical modification of plant kenaf biomass was tested for its efficacy as a sorbent material towards the purification of waste water. The K-IDA fiber was first characterized by the instrumental techniques like Fourier transform infrared (FTIR) analysis, elemental analysis (CHNSO), and scanning electron microscopy (SEM). On testing for the biosorption, we found that the K-IDA has an increment in the adsorption of Cu 2+ ions as compared against the untreated fiber. The Cu 2+ ions adsorption onto K-IDA fits very well with the Langmuir model and the adsorption maximum achieved to be 91.74mg/g. Further, the adsorption kinetics observed to be pseudo second-order kinetics model and the Cu 2+ ions adsorption is a spontaneous endothermic process. The desorption study indicates a highest percentage of Cu 2+ of 97.59% from K-IDA under 1M HCl solution against H 2 SO 4 (72.59%) and HNO 3 (68.66%). The reusability study indicates that the efficiency did not change much until the 4th cycle and also providing enough evidence for the engagement of our biodegradable K-IDA fiber towards the removal of Cu 2+ ions in real-time waste water samples obtained from the electroplating and wood treatment industries. Copyright © 2018. Published by Elsevier B.V.

Metal-Chelate Immobilization of Lipase onto Polyethylenimine Coated MCM-41 for Apple Flavor Synthesis.

PubMed

Sadighi, Armin; Motevalizadeh, Seyed Farshad; Hosseini, Morteza; Ramazani, Ali; Gorgannezhad, Lena; Nadri, Hamid; Deiham, Behnaz; Ganjali, Mohammad Reza; Shafiee, Abbas; Faramarzi, Mohammad Ali; Khoobi, Mehdi

2017-08-01

An enzyme immobilized on a mesoporous silica nanoparticle can serve as a multiple catalyst for the synthesis of industrially useful chemicals. In this work, MCM-41 nanoparticles were coated with polyethylenimine (MCM-41@PEI) and further modified by chelation of divalent metal ions (M = Co 2+ , Cu 2+ , or Pd 2+ ) to produce metal-chelated silica nanoparticles (MCM-41@PEI-M). Thermomyces lanuginosa lipase (TLL) was immobilized onto MCM-41, MCM-41@PEI, and MCM-41@PEI-M by physical adsorption. Maximum immobilization yield and efficiency of 75 ± 3.5 and 65 ± 2.7% were obtained for MCM@PEI-Co, respectively. The highest biocatalytic activity at extremely acidic and basic pH (pH = 3 and 10) values were achieved for MCM-PEI-Co and MCM-PEI-Cu, respectively. Optimum enzymatic activity was observed for MCM-41@PEI-Co at 75 °C, while immobilized lipase on the Co-chelated support retained 70% of its initial activity after 14 days of storage at room temperature. Due to its efficient catalytic performance, MCM-41@PEI-Co was selected for the synthesis of ethyl valerate in the presence of valeric acid and ethanol. The enzymatic esterification yield for immobilized lipase onto MCM-41@PEI-Co was 60 and 53%, respectively, after 24 h of incubation in n-hexane and dimethyl sulfoxide media. Graphical Abstract Divalent metal chelated polyethylenimine coated MCM-41 (MCM-41@PEI-M) was used for immobilization of Thermomyces lanuginosa lipase catalyzing green apple flavor preparation.

Extracellular chelation of zinc does not affect hippocampal excitability and seizure-induced cell death in rats

PubMed Central

Lavoie, Nathalie; Peralta, Modesto R; Chiasson, Marilou; Lafortune, Kathleen; Pellegrini, Luca; Seress, László; Tóth, Katalin

2007-01-01

In the nervous system, zinc can influence synaptic responses and at extreme concentrations contributes to epileptic and ischaemic neuronal injury. Zinc can originate from synaptic vesicles, the extracellular space and from intracellular stores. In this study, we aimed to determine which of these zinc pools is responsible for the increased hippocampal excitability observed in zinc-depleted animals or following zinc chelation. Also, we investigated the source of intracellularly accumulating zinc in vulnerable neurons. Our data show that membrane-permeable and membrane-impermeable zinc chelators had little or no effect on seizure activity in the CA3 region. Furthermore, extracellular zinc chelation could not prevent the accumulation of lethal concentrations of zinc in dying neurons following epileptic seizures. At the electron microscopic level, zinc staining significantly increased at the presynaptic membrane of mossy fibre terminals in kainic acid-treated animals. These data indicate that intracellular but not extracellular zinc chelators could influence neuronal excitability and seizure-induced zinc accumulation observed in the cytosol of vulnerable neurons. PMID:17095563

Ga(III) chelates of amphiphilic DOTA-based ligands: synthetic route and in vitro and in vivo studies.

PubMed

Fontes, André; Prata, M Isabel M; Geraldes, Carlos F G C; André, João P

2011-04-01

In this work, we report on a synthetic strategy using amphiphilic DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid)-based chelators bearing a variable-sized α-alkyl chain at one of the pendant acetate arms (from 6 to 14 carbon atoms), compatible with their covalent coupling to amine-bearing biomolecules. The amphiphilic behavior of the micelles-forming Ga(III) chelates (critical micellar concentration), their stability in blood serum and their lipophilicity (logP) were investigated. Biodistribution studies with the (67)Ga-labeled chelates were performed in Wistar rats, which showed a predominant liver uptake with almost no traces of the radiochelates in the body after 24 h. Copyright © 2011 Elsevier Inc. All rights reserved.

Reversible adsorption of catalase onto Fe(3+) chelated poly(AAm-GMA)-IDA cryogels.

PubMed

Aktaş Uygun, Deniz; Uygun, Murat; Akgöl, Sinan; Denizli, Adil

2015-05-01

In this presented study, poly(acrylamide-glycidyl methacrylate) [poly(AAm-GMA)] cryogels were synthesized by cryopolymerization technique at sub-zero temperature. Prepared cryogels were then functionalized with iminodiacetic acid (IDA) and chelated with Fe(3+) ions in order produce the metal chelate affinity matrix. Synthesized cryogels were characterized with FTIR, ESEM and EDX analysis, and it was found that the cryogel had sponge like structure with interconnected pores and their pore diameter was about 200 μm. Fe(3+) chelated poly(AAm-GMA)-IDA cryogels were used for the adsorption of catalase and optimum adsorption conditions were determined by varying the medium pH, initial catalase concentration, temperature and ionic strength. Maximum catalase adsorption onto Fe(3+) chelated poly(AAm-GMA)-IDA cryogel was found to be 12.99 mg/g cryogel at 25 °C, by using pH 5.0 acetate buffer. Adsorbed catalase was removed from the cryogel by using 1.0M of NaCl solution and desorption yield was found to be 96%. Additionally, reusability profile of the Fe(3+) chelated poly(AAm-GMA)-IDA cryogel was also investigated and it was found that, adsorption capacity of the cryogels didn't decrease significantly at the end of the 40 reuses. Catalase activity studies were also tested and it was demonstrated that desorbed catalase retained 70% of its initial activity. Copyright © 2015 Elsevier B.V. All rights reserved.

Single-mode large-mode-area laser fiber with ultralow numerical aperture and high beam quality.

PubMed

Peng, Kun; Zhan, Huan; Ni, Li; Wang, Xiaolong; Wang, Yuying; Gao, Cong; Li, Yuwei; Wang, Jianjun; Jing, Feng; Lin, Aoxiang

2016-12-10

By using the chelate precursor doping technique, we report on an ytterbium-doped aluminophosphosilicate (APS) large-mode-area fiber with ultralow numerical aperture of 0.036 and effective fundamental mode area of ∼550  μm². With a bend diameter of 600 mm, the bending loss of fundamental mode LP₀₁ was measured to be <10^-3  dB/m, in agreement with the corresponding simulation results, while that of higher order mode LP₁₁ is >100  dB/m at 1080 nm. Measured in an all-fiber oscillator laser cavity, 592 W single-mode laser output was obtained at 1079.64 nm with high-beam quality M² of 1.12. The results indicate that the chelate precursor doping technique is a competitive method for ultralow numerical aperture fiber fabrication, which is very suitable for developing single-mode seed lasers for high power laser systems.

Method for preparing radionuclide-labeled chelating agent-ligand complexes

DOEpatents

Meares, Claude F.; Li, Min; DeNardo, Sally J.

1999-01-01

Radionuclide-labeled chelating agent-ligand complexes that are useful in medical diagnosis or therapy are prepared by reacting a radionuclide, such as .sup.90 Y or .sup.111 In, with a polyfunctional chelating agent to form a radionuclide chelate that is electrically neutral; purifying the chelate by anion exchange chromatography; and reacting the purified chelate with a targeting molecule, such as a monoclonal antibody, to form the complex.

Searching for new aluminium chelating agents: a family of hydroxypyrone ligands.

PubMed

Toso, Leonardo; Crisponi, Guido; Nurchi, Valeria M; Crespo-Alonso, Miriam; Lachowicz, Joanna I; Mansoori, Delara; Arca, Massimiliano; Santos, M Amélia; Marques, Sérgio M; Gano, Lurdes; Niclós-Gutíerrez, Juan; González-Pérez, Josefa M; Domínguez-Martín, Alicia; Choquesillo-Lazarte, Duane; Szewczuk, Zbigniew

2014-01-01

Attention is devoted to the role of chelating agents in the treatment of aluminium related diseases. In fact, in spite of the efforts that have drastically reduced the occurrence of aluminium dialysis diseases, they so far constitute a cause of great medical concern. The use of chelating agents for iron and aluminium in different clinical applications has found increasing attention in the last thirty years. With the aim of designing new chelators, we synthesized a series of kojic acid derivatives containing two kojic units joined by different linkers. A huge advantage of these molecules is that they are cheap and easy to produce. Previous works on complex formation equilibria of a first group of these ligands with iron and aluminium highlighted extremely good pMe values and gave evidence of the ability to scavenge iron from inside cells. On these bases a second set of bis-kojic ligands, whose linkers between the kojic chelating moieties are differentiated both in terms of type and size, has been designed, synthesized and characterized. The aluminium(III) complex formation equilibria studied by potentiometry, electrospray ionization mass spectroscopy (ESI-MS), quantum-mechanical calculations and (1)H NMR spectroscopy are here described and discussed, and the structural characterization of one of these new ligands is presented. The in vivo studies show that these new bis-kojic derivatives induce faster clearance from main organs as compared with the monomeric analog. © 2013.

Low dielectric polyimide fibers

NASA Technical Reports Server (NTRS)

Dorogy, William E., Jr. (Inventor); St.clair, Anne K. (Inventor)

1994-01-01

A high temperature resistant polyimide fiber that has a dielectric constant of less than 3 is presented. The fiber was prepared by first reacting 2,2-bis (4-(4aminophenoxy)phenyl) hexafluoropropane with 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride in an aprotic solvent to form a polyamic acid resin solution. The polyamic acid resin solution is then extruded into a coagulation medium to form polyamic acid fibers. The fibers are thermally cured to their polyimide form. Alternatively, 2,2-bis(4-(4-aminophenoxy)phenyl) hexafluoropropane is reacted with 2,2-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride to form a polyamic acid, and the polyamic acid is chemically converted to its polyimide form. The polyimide is then dissolved in a solvent to form a polyimide resin solution, and the polyimide resin is extruded into a coagulation medium to form a polyimide wet gel filament. In order to obtain polyimide fibers of increased tensile properties, the polyimide wet gel filaments are stretched at elevated temperatures. The tensile properties of the fibers were measured and found to be in the range of standard textile fibers. Polyimide fibers obtained by either method will have a dielectric constant similar to that of the corresponding polymer, viz., less than 3 at 10 GHz.

Biodegradable chelate enhances the phytoextraction of copper by Oenothera picensis grown in copper-contaminated acid soils.

PubMed

González, Isabel; Cortes, Amparo; Neaman, Alexander; Rubio, Patricio

2011-07-01

Oenothera picensis plants (Fragrant Evening Primrose) grow in the acid soils contaminated by copper smelting in the coastal region of central Chile. We evaluated the effects of the biodegradable chelate MGDA (methylglycinediacetic acid) on copper extraction by O. picensis and on leaching of copper through the soil profile, using an ex situ experiment with soil columns of varying heights. MGDA was applied in four rates: 0 (control), 2, 6 and 10 mmol plant(-1). MGDA application significantly increased biomass production and foliar concentration, permitting an effective increase in copper extraction, from 0.09 mg plant(-1) in the control, to 1.3mg plant(-1) in the 6 and 10 mmol plant(-1) treatments. With 10 mmol plant(-1) rate of MGDA, the copper concentration in the leachate from the 30 cm columns was 20 times higher than in the control. For the 60 cm columns, copper concentration was 2 times higher than the control. It can be concluded that at increased soil depths, copper leaching would be minimal and that MGDA applications at the studied rates would not pose a high risk for leaching into groundwater. It can thus be stated that applications of MGDA are an effective and environmentally safe way to improve copper extraction by O. picensis in these soils. Copyright © 2011 Elsevier Ltd. All rights reserved.

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

USDA-ARS?s Scientific Manuscript database

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...

Preparation and Adsorption Property of Imido-acetic Acid Type Chelating Nano-fibers by Electro-spinning Technique

NASA Astrophysics Data System (ADS)

Yang, Jiali; Lu, Lansi; Zhang, Zhu; Liao, Minhui; He, Huirong; Li, Lingxing; Chen, Jida; Chen, Shijin

2017-12-01

A novel nano-fibrous adsorbent from imino-acetic acid (IDA) and polyvinyl alcohol (PVA) mixture solution was prepared by electro-spinning technique. The nano-fibrous adsorbents with imino-acetic acid functional groups were characterized and demonstrated by fourier transform infrared spectrometry (FT-IR) and the scanning electron microscopy (SEM). The effect of the adsorbents to remove heavy metals such as lead (Pb) and copper (Cu) ions from the aqueous solution was studied. The maximum adsorption percentage (SP) of the metal ions can reach 93.08% for Cu (II) and 96.69% for Pb(II), respectively. Furthermore, it shows that the adsorption procedure of the adsorbents is spontaneous and endothermic, and adsorption rate fits well with pseudo-second-order kinetic model. Most importantly, the reusability of the nanofibers for removal of metal ions was also demonstrated to be used at least five times.

EDTA chelation effects on urinary losses of cadmium, calcium, chromium, cobalt, copper, lead, magnesium, and zinc.

PubMed

Waters, R S; Bryden, N A; Patterson, K Y; Veillon, C; Anderson, R A

2001-12-01

The efficacy of a chelating agent in binding a given metal in a biological system depends on the binding constants of the chelator for the particular metals in the system, the concentration of the metals, and the presence and concentrations of other ligands competing for the metals in question. In this study, we make a comparison of the in vitro binding constants for the chelator, ethylenediaminetetraacetic acid, with the quantitative urinary excretion of the metals measured before and after EDTA infusion in 16 patients. There were significant increases in lead, zinc, cadmium, and calcium, and these increases roughly corresponded to the expected relative increases predicted by the EDTA-metal-binding constants as measured in vitro. There were no significant increases in urinary cobalt, chromium, or copper as a result of EDTA infusion. The actual increase in cobalt could be entirely attributed to the cobalt content of the cyanocobalamin that was added to the infusion. Although copper did increase in the post-EDTA specimens, the increase was not statistically significant. In the case of magnesium, there was a net retention of approximately 85% following chelation. These data demonstrate that EDTA chelation therapy results in significantly increased urinary losses of lead, zinc, cadmium, and calcium following EDTA chelation therapy. There were no significant changes in cobalt, chromium, or copper and a retention of magnesium. These effects are likely to have significant effects on nutrient concentrations and interactions and partially explain the clinical improvements seen in patients undergoing EDTA chelation therapy.

Enzymes and chelating agent in cotton pretreatment.

PubMed

Csiszár, E; Losonczi, A; Szakács, G; Rusznák, I; Bezúr, L; Reicher, J

2001-08-23

Desized cotton fabric and cotton seed-coat fragments (impurities) have been treated with commercial cellulase (Celluclast 1.5 L), hemicellulase-pectinase (Viscozyme 120 L) and xylanase (Pulpzyme HC) enzymes. Seed-coat fragments hydrolyzed much faster than the cotton fabric itself. This relative difference in hydrolysis rates makes possible a direct enzymatic removal of seed-coat fragments from desized cotton fabric. Addition of chelating agents such as ethylenediamine-tetra-acetic acid (EDTA) markedly enhanced the directed enzyme action. Pretreatments carried out in acidic solution at pH 5 increased the lightness of seed-coat fragments, contrary to the samples treated in neutral medium at pH 7. Alkaline scouring resulted in darker seed-coat fragments except for the samples pretreated with Pulpzyme HC plus EDTA. This effect is similar to that observed in the biobleaching process in pulp and paper industry.

Electron-beam-induced post-grafting polymerization of acrylic acid onto the surface of Kevlar fibers

NASA Astrophysics Data System (ADS)

Xu, Lu; Hu, Jiangtao; Ma, Hongjuan; Wu, Guozhong

2018-04-01

The surface of Kevlar fibers was successfully modified by electron beam (EB)-induced post-grafting of acrylic acid (AA). The generation of radicals in the fibers was confirmed by electron spin resonance (ESR) measurements, and the concentration of radicals was shown to increase as the absorbed dose increased, but decrease with increasing temperature. The influence of the synthesis conditions on the degree of grafting was also investigated. The surface microstructure and chemical composition of the modified Kevlar fibers were characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The SEM images revealed that the surface of the grafted fibers was rougher than those of the pristine and irradiated fibers. XPS analysis confirmed an increase in C(O)OH groups on the surface of the Kevlar fibers, suggesting successful grafting of AA. These results indicate that EB-induced post-grafting polymerization is effective for modifying the surface properties of Kevlar fibers.

FTIR, magnetic, 1H NMR spectral and thermal studies of some chelates of caproic acid: inhibitory effect on different kinds of bacteria.

PubMed

Refat, Moamen S; El-Korashy, Sabry A; Kumar, Deo Nandan; Ahmed, Ahmed S

2008-06-01

A convenient method for the preparation of complexes of the Cr3+, Mn2+, Fe3+, Co2+, Ni2+, Zn2+, ZrO2+, UO2(2+), Zr4+ and Th4+ ions with caproic acid (Hcap) is reported and this has enabled 10 complexes of caproate anion to be formulated: [Cr(cap)3].5H2O, [Mn(cap)2(H2O)2], [Fe(cap)3].12H2O, [Co(cap)2(H2O)2].4H2O, [Ni(cap)2(H2O)2].3H2O, [Zn(cap)2], [ZrO(cap)2].3H2O, [UO2(cap)(NO3)], [Zr(cap)2(Cl)2] and [Th(cap)4]. These new complexes were synthesized and characterized by elemental analysis, molar conductivity, magnetic measurements, spectral methods (mid infrared, 1H NMR and UV-vis spectra) and simultaneous thermal analysis (TG and DTG) techniques. It has been found from the elemental analysis as well as thermal studies that the caproate ligand behaves as bidentate ligand and forming chelates with 1:1 (metal:ligand) stoichiometry for UO2(2+), 1:2 for (Mn2+, Co2+, Ni2+, Zn2+, ZrO2+ and Zr4+), 1:3 stoichiometry for (Cr3+ and Fe3+) and 1:4 for Th4+ caproate complexes, respectively, as bidentate chelating. The molar conductance measurements proved that the caproate complexes are non-electrolytes. The kinetic thermodynamic parameters such as: E*, DeltaH*, DeltaS* and DeltaG* are estimated from the DTG curves. The antibacterial activity of the caproic acid and their complexes was evaluated against some gram positive/negative bacteria.

Antibacterial poly(lactic acid) (PLA) films grafting electrospun PLA/Ally isothioscyanate (AITC) fibers for food packaging

USDA-ARS?s Scientific Manuscript database

Poly(lactic acid) (PLA) fibers of submicron sizes encapsulating allyl isothiocyanate (AITC) (PfA) were made and electrospun onto the surfaces of PLA films (PfA-g-film). SEM examination confirmed that the fibers were grafted to the PLA film after the (PfA-g-film) underwent air blowing and water washi...

Ethylenediaminetetraacetic acid in endodontics

PubMed Central

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 its usage are presented. PMID:24966721

Bioinspired Interfacial Chelating-like Reinforcement Strategy toward Mechanically Enhanced Lamellar Materials.

PubMed

Chen, Ke; Zhang, Shuhao; Li, Anran; Tang, Xuke; Li, Lidong; Guo, Lin

2018-05-22

Many biological organisms usually derived from the ordered assembly of heterogeneous, hierarchical inorganic/organic constituents exhibit outstanding mechanical integration, but have proven to be difficult to produce the combination of excellent mechanical properties, such as strength, toughness, and light weight, by merely mimicking their component and structural characteristics. Herein, inspired by biologically strong chelating interactions of phytic acid (PA) or IP6 in many biomaterials, we present a biologically interfacial chelating-like reinforcement (BICR) strategy for fabrication of a highly dense ordered "brick-and-mortar" microstructure by incorporating tiny amounts of a natural chelating agent ( e. g., PA) into the interface or the interlamination of a material ( e. g., graphene oxide (GO)), which shows joint improvement in hardness (∼41.0%), strength (∼124.1%), maximum Young's modulus (∼134.7%), and toughness (∼118.5%) in the natural environment. Besides, for different composite matrix systems and artificial chelating agents, the BICR strategy has been proven successful for greatly enhancing their mechanical properties, which is superior to many previous reinforcing approaches. This point can be mainly attributed to the stronger noncovalent cross-linking interactions such as dense hydrogen bonds between the richer phosphate (hydroxyl) groups on its cyclohexanehexol ring and active sites of GO, giving rise to the larger energy dissipation at its hybrid interfaces. It is also simple and environmentally friendly for further scale-up fabrication and can be readily extended to other material systems, which opens an advanced reinforcement route to construct structural materials with high mechanical performance in an efficient way for practical applications.

Iron chelation and multiple sclerosis

PubMed Central

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

2014-01-01

Histochemical and MRI studies have demonstrated that MS (multiple sclerosis) patients have abnormal deposition of iron in both gray and white matter structures. Data is emerging indicating that this iron could partake in pathogenesis by various mechanisms, e.g., promoting the production of reactive oxygen species and enhancing the production of proinflammatory cytokines. Iron chelation therapy could be a viable strategy to block iron-related pathological events or it can confer cellular protection by stabilizing hypoxia inducible factor 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. PMID:24397846

Iron-[S,S']-EDDS (FeEDDS) Chelate as an Iron Source for Horticultural Crop Production: Marigold Growth and Nutrition, Spectral Properties, and Photodegradation

USDA-ARS?s Scientific Manuscript database

Aminopolycarboxylic acid (APCA) complexones, commonly referred to as ligands or chelating agents, like ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA) are commonly used in soluble fertilizers to supply copper (Cu), iron (Fe), manganese (Mn), and/or zinc (Zn) to p...

Transglutaminase-mediated conjugation and nitride-technetium-99m labelling of a bis(thiosemicarbazone) bifunctional chelator.

PubMed

Salvarese, Nicola; Spolaore, Barbara; Marangoni, Selena; Pasin, Anna; Galenda, Alessandro; Tamburini, Sergio; Cicoria, Gianfranco; Refosco, Fiorenzo; Bolzati, Cristina

2018-06-01

An assessment study involving the use of the transglutaminase (TGase) conjugation method and the nitride-technetium-99m labelling on a bis(thiosemicarbazone) (BTS) bifunctional chelating agent is presented. The previously described chelator diacetyl-2-(N 4 -methyl-3-thiosemicarbazone)-3-(N 4 -amino-3-thiosemicarbazone), H 2 ATSM/A, has been functionalized with 6-aminohexanoic acid (ε-Ahx) to generate the bifunctional chelating agent diacetyl-2-(N 4 -methyl-3-thiosemicarbazone)-3-[N 4 -(amino)-(6-aminohexanoic acid)-3-thiosemicarbazone], H 2 ATSM/A-ε-Ahx (1), suitable for conjugation to glutamine (Gln) residues of bioactive molecules via TGase. The feasibility of the TGase reaction in the synthesis of a bioconjugate derivative was investigated using Substance P (SP) as model peptide. Compounds 1 and H 2 ATSM/A-ε-Ahx-SP (2) were labelled with nitride-technetium-99m, obtaining the complexes [ 99m Tc][Tc(N)(ATSM/A-ε-Ahx)] ( 99m Tc1) and [ 99m Tc][Tc(N)(ATSM/A-ε-Ahx-SP)] ( 99m Tc2). The chemical identity of 99m Tc1 and 99m Tc2 was confirmed by radio/UV-RP-HPLC combined with ESI-MS analysis on the respective carrier-added products 99g/99m Tc1 and 99g/99m Tc2. The stability of the radiolabelled complexes after incubation in various environments was investigated. All the results were compared with those obtained for the corresponding 64 Cu-analogues, 64 Cu1 and 64 Cu2. The TGase reaction allows the conjugation of 1 with the peptide, but it is not highly efficient due to instability of the chelator in the required conditions. The SP-conjugated complexes are unstable in mouse and human sera. However, indeed the BTS system can be exploited as nitride-technetium-99m chelator for highly efficient technetium labelling, thus making compound 1 worthy of further investigations for new targeted technetium and copper radiopharmaceuticals encompassing Single Photon Emission Computed Tomography and Positron Emission Tomography imaging. Copyright © 2018 Elsevier Inc. All rights

Deferasirox-Iron Complex Formation Ratio as an Indicator of Long-term Chelation Efficacy in β-Thalassemia Major.

PubMed

Lu, Meng-Yao; Lin, Ting-Hao; Chiang, Po-Hung; Kuo, Pei-Hsin; Wang, Ning; Wu, Wen-Hsin; Lin, Kai-Hsin; Wu, Tzu-Hua

2017-04-01

β-Thalassemia major patients with higher total drug levels [deferasirox (DEFR) plus its iron complex] do not yield better serum ferritin (SF) control. This study aimed to determine the concentrations of DEFR and its iron complex (Fe-[DEFR]2) in thalassemia patients to predict the chelation efficacy in terms of SF and cardiac T2* values. Patients' steady-state drug levels at trough (Ctrough) and 2 hours postdose (C2h) were determined. Because iron deposition may cause changes in the hepatic metabolism of amino acids, the concentrations of 40 amino acids in plasma were also assayed at 2 hours postdose. A total of 28 patients either dosing daily or twice daily were recruited. After a 1-month DEFR maintenance therapy, 38.8% and 30% of patients from groups of once-daily and twice-daily, respectively, had a plasma DEFR-iron complex formation ratio higher than 0.05 [High Chelation Ratio, (HCR)]. After a 6-month follow-up, those patients who had a HCR (n = 10) at C2h showed more favorable median changes in SF and cardiac T2* values (-388.0, +10.1) than those with a low DEFR-iron complex formation ratio (Low Chelation Ratio; n = 18; +10.5; +4.5) compared with the baseline. The levels of plasma L-arginine, L-alanine, L-glycine, L-norleucine, and L-serine were significantly lower in patients with the low Chelation Ratio condition than the levels in HCR patients. This therapeutic drug monitoring study revealed that a DEFR-iron complex formation ratio at C2h might be an applicable indicator of the efficacy of long-term DEFR iron chelation therapy. A better iron-control response to DEFR was observed in the patients with HCRs. The trends for the ratio might have value in dose-setting and need to be validated in a larger cohort.

Lipid production by Cryptococcus curvatus on hydrolysates derived from corn fiber and sweet sorghum bagasse following dilute acid pretreatment.

PubMed

Liang, Yanna; Jarosz, Kimberly; Wardlow, Ashley T; Zhang, Ji; Cui, Yi

2014-08-01

Corn fiber and sweet sorghum bagasse (SSB) are both pre-processed lignocellulosic materials that can be used to produce liquid biofuels. Pretreatment using dilute sulfuric acid at a severity factor of 1.06 and 1.02 released 83.2 and 86.5 % of theoretically available sugars out of corn fiber and SSB, respectively. The resulting hydrolysates derived from pretreatment of SSB at SF of 1.02 supported growth of Cryptococcus curvatus well. In 6 days, the dry cell density reached 10.8 g/l with a lipid content of 40 % (w/w). Hydrolysates from corn fiber, however, did not lead to any significant cell growth even with addition of nutrients. In addition to consuming glucose, xylose, and arabinose, C. curvatus also utilized formic acid, acetic acid, 4-hydroxymethylfurfural, and levulinic acid for growth. Thus, C. curvatus appeared to be an excellent yeast strain for producing lipids from hydrolysates developed from lignocellulosic feedstocks.

In vitro inhibition of bacterial growth by iron chelators.

PubMed

Qiu, Di-Hong; Huang, Zhu-Liang; Zhou, Tao; Shen, Chen; Hider, Robert C

2011-01-01

The antimicrobial activity of the iron(III)-selective 3-hydroxypyridin-4-one chelators, CP251(1) and CP252(2), was evaluated in comparison with that of diethylenetriamine-penta acetic acid (3). CP251 was found to exhibit an inhibitory effect on the growth of both Gram-positive and Gram-negative bacteria. CP251 may find application in the treatment of external infections such as those associated with wounds. © 2010 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

Oxidation-Induced Degradable Nanogels for Iron Chelation

NASA Astrophysics Data System (ADS)

Liu, Zhi; Wang, Yan; Purro, Max; Xiong, May P.

2016-02-01

Iron overload can increase cellular oxidative stress levels due to formation of reactive oxygen species (ROS); untreated, it can be extremely destructive to organs and fatal to patients. Since elevated oxidative stress levels are inherent to the condition in such patients, oxidation-induced degradable nanogels for iron chelation were rationally designed by simultaneously polymerizing oxidation-sensitive host-guest crosslinkers between β-cyclodextrin (β-CD) and ferrocene (Fc) and iron chelating moieties composed of deferoxamine (DFO) into the final gel scaffold in reverse emulsion reaction chambers. UV-Vis absorption and atomic absorption spectroscopy (AAS) was used to verify iron chelating capability of nanogels. These materials can degrade into smaller chelating fragments at rates proportional to the level of oxidative stress present. Conjugating DFO reduces the cytotoxicity of the chelator in the macrophage cells. Importantly, the nanogel can effectively reduce cellular ferritin expression in iron overloaded cells and regulate intracellular iron levels at the same time, which is important for maintaining a homeostatic level of this critical metal in cells.

Oxidation-Induced Degradable Nanogels for Iron Chelation

PubMed Central

Liu, Zhi; Wang, Yan; Purro, Max; Xiong, May P.

2016-01-01

Iron overload can increase cellular oxidative stress levels due to formation of reactive oxygen species (ROS); untreated, it can be extremely destructive to organs and fatal to patients. Since elevated oxidative stress levels are inherent to the condition in such patients, oxidation-induced degradable nanogels for iron chelation were rationally designed by simultaneously polymerizing oxidation-sensitive host-guest crosslinkers between β-cyclodextrin (β-CD) and ferrocene (Fc) and iron chelating moieties composed of deferoxamine (DFO) into the final gel scaffold in reverse emulsion reaction chambers. UV-Vis absorption and atomic absorption spectroscopy (AAS) was used to verify iron chelating capability of nanogels. These materials can degrade into smaller chelating fragments at rates proportional to the level of oxidative stress present. Conjugating DFO reduces the cytotoxicity of the chelator in the macrophage cells. Importantly, the nanogel can effectively reduce cellular ferritin expression in iron overloaded cells and regulate intracellular iron levels at the same time, which is important for maintaining a homeostatic level of this critical metal in cells. PMID:26868174

Amino acid specificity of fibers of the facial/trigeminal complex innervating the maxillary barbel in the Japanese sea catfish, Plotosus japonicus.

PubMed

Caprio, John; Shimohara, Mami; Marui, Takayuki; Kohbara, Jun; Harada, Shuitsu; Kiyohara, Sadao

2015-12-01

The Japanese sea catfish, Plotosus japonicus, possesses taste and solitary chemoreceptor cells (SCCs) located on the external body surface that detect specific water-soluble substances. Here, we identify two major fiber types of the facial/trigeminal complex that transmit amino acid information to the medulla. Both single and few fiber preparations respond to amino acid stimulation in the 0.1 μM to mM range. One fiber type responds best to glycine and l-alanine (i.e. Gly/Ala fibers) whereas the other fiber type is best stimulated by l-proline and glycine betaine (hereafter referred to only as betaine) (i.e. Pro/Bet fibers). We demonstrate that betaine, which does not alter the pH of the seawater and therefore does not activate the animals' highly sensitive pH sensors (Caprio et al., Science 344:1154-1156, 2014), is sufficient to elicit appetitive food search behavior. We further show that the amino acid specificity of fibers of the facial/trigeminal complex in P. japonicus is different from that in Ariopsis felis (Michel and Caprio, J. Neurophysiol. 66:247-260, 1991; Michel et al., J. Comp. Physiol. A. 172:129-138, 1993), a representative member of the only other family (Ariidae) of extant marine catfishes. Copyright © 2015 Elsevier Inc. All rights reserved.

BN Bonded BN fiber article from boric oxide fiber

DOEpatents

Hamilton, Robert S.

1978-12-19

A boron nitride bonded boron nitride fiber article and the method for its manufacture which comprises forming a shaped article with a composition comprising boron oxide fibers and boric acid, heating the composition in an anhydrous gas to a temperature above the melting point of the boric acid and nitriding the resulting article in ammonia gas.

Timed non-transferrin bound iron determinations probe the origin of chelatable iron pools during deferiprone regimens and predict chelation response

PubMed Central

Aydinok, Yesim; Evans, Patricia; Manz, Chantal Y.; Porter, John B.

2012-01-01

Background Plasma non-transferrin bound iron refers to heterogeneous plasma iron species, not bound to transferrin, which appear in conditions of iron overload and ineffective erythropoiesis. The clinical utility of non-transferrin bound iron in predicting complications from iron overload, or response to chelation therapy remains unproven. We undertook carefully timed measurements of non-transferrin bound iron to explore the origin of chelatable iron and to predict clinical response to deferiprone. Design and Methods Non-transferrin bound iron levels were determined at baseline and after 1 week of chelation in 32 patients with thalassemia major receiving deferiprone alone, desferrioxamine alone, or a combination of the two chelators. Samples were taken at baseline, following a 2-week washout without chelation, and after 1 week of chelation, this last sample being taken 10 hours after the previous evening dose of deferiprone and, in those receiving desferrioxamine, 24 hours after cessation of the overnight subcutaneous infusion. Absolute or relative non-transferrin bound iron levels were related to transfusional iron loading rates, liver iron concentration, 24-hour urine iron and response to chelation therapy over the subsequent year. Results Changes in non-transferrin bound iron at week 1 were correlated positively with baseline liver iron, and inversely with transfusional iron loading rates, with deferiprone-containing regimens but not with desferrioxamine monotherapy. Changes in week 1 non-transferrin bound iron were also directly proportional to the plasma concentration of deferiprone-iron complexes and correlated significantly with urine iron excretion and with changes in liver iron concentration over the next 12 months. Conclusions The widely used assay chosen for this study detects both endogenous non-transferrin bound iron and the iron complexes of deferiprone. The week 1 increments reflect chelatable iron derived both from liver stores and from red cell

Two-step sulfonation process for the conversion of polymer fibers to carbon fibers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barton, Bryan E.; Patton, Jasson T.; Hukkanen, Eric J.

Disclosed herein are processes for preparing carbon fibers, comprising: sulfonating a polymer fiber with a sulfonating agent that is fuming sulfuric acid, sulfuric acid, chlorosulfonic acid, or a combination thereof; treating the sulfonated polymer with a heated solvent, wherein the temperature of the heated solvent is at least 95.degree. C.; and carbonizing the resulting product by heating it to a temperature of 501-3000.degree. C. Carbon fibers prepared according to these methods are also disclosed herein.

Molecular engineering of lanthanide ion chelating phospholipids generating assemblies with a switched magnetic susceptibility.

PubMed

Isabettini, Stéphane; Massabni, Sarah; Hodzic, Arnel; Durovic, Dzana; Kohlbrecher, Joachim; Ishikawa, Takashi; Fischer, Peter; Windhab, Erich J; Walde, Peter; Kuster, Simon

2017-08-09

Lanthanide ion (Ln 3+ ) chelating amphiphiles are powerful molecules for tailoring the magnetic response of polymolecular assemblies. Mixtures of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and 1,2-dimyristoyl-sn-glycero-3-phospho-ethanolamine-diethylene triaminepentaacetate (DMPE-DTPA) complexed to Ln 3+ deliver highly magnetically responsive bicelles. Their magnetic properties are readily tuned by changing the bicellar size or the magnetic susceptibility Δχ of the bilayer lipids. The former technique is intrinsically bound to the region of the phase diagram guarantying the formation of bicelles. Methods aiming towards manipulating the Δχ of the bilayer are comparatively more robust, flexible and lacking. Herein, we synthesized a new Ln 3+ chelating phospholipid using glutamic acid as a backbone: DMPE-Glu-DTPA. The chelate polyhedron was specifically engineered to alter the Δχ, whilst remaining geometrically similar to DMPE-DTPA. Planar asymmetric assemblies hundreds of nanometers in size were achieved presenting unprecedented magnetic alignments. The DMPE-Glu-DTPA/Ln 3+ complex switched the Δχ, achieving perpendicular alignment of assemblies containing Dy 3+ and parallel alignment of those containing Tm 3+ . Moreover, samples with chelated Yb 3+ were more alignable than the Tm 3+ chelating counterparts. Such a possibility has never been demonstrated for planar Ln 3+ chelating polymolecular assemblies. The physico-chemical properties of these novel assemblies were further studied by monitoring the alignment behavior at different temperatures and by including 16 mol% of cholesterol (Chol-OH) in the phospholipid bilayer. The DMPE-Glu-DTPA/Ln 3+ complex and the resulting assemblies are promising candidates for applications in numerous fields including pharmaceutical technologies, structural characterization of membrane biomolecules by NMR spectroscopy, as contrasting agents for magnetic resonance imaging, and for the development of smart optical gels.

Enzyme-entrapping behaviors in alginate fibers and their papers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kobayashi, Y.; Matsuo, R.; Ohya, T.

1987-01-01

Enzyme immobilization in the form of fiber and paper was easily achieved by wet spinning of aqueous admixture of sodium alginate and enzymes into divalent metallic ion solution as a coagulating bath, followed by paper making of resultant shortly cut fibers. Entrapment yields of enzymes used, e.g., glucoamylase, cyclodextrin glucanotransferase, endo-polygalacturonase, and protease, were always higher in calcium alginate fibers and their papers than those in corresponding beads. It was found that the yields increased with an increase of the discharge rate through the spinning nozzle because the higher discharge rate could provide more highly oriented metal-chelate linear polymer moleculesmore » along the fiber axis for preventing leakage of entrapped enzymes. Divalent metallic ions affected greatly the entrapment of glucoamylase in alginate fibers, the order of which followed rougly the ionotropic series of Thiele. Entrapment of glucoamylase in bicomponent systems comprising alginate and other water-soluble polymers was also investigated. (Refs. 41).« less

Questions and Answers on Unapproved Chelation Products

MedlinePlus

... OTC) to prevent or treat diseases. Companies are marketing unapproved OTC chelation therapy products to patients with ... 4. Why did FDA take this action? Companies marketing unapproved OTC chelation products with unsubstantiated treatment claims ...

Isolation and characterization of iron chelators from turmeric (Curcuma longa): selective metal binding by curcuminoids.

PubMed

Messner, Donald J; Surrago, Christine; Fiordalisi, Celia; Chung, Wing Yin; Kowdley, Kris V

2017-10-01

Iron overload disorders may be treated by chelation therapy. This study describes a novel method for isolating iron chelators from complex mixtures including plant extracts. We demonstrate the one-step isolation of curcuminoids from turmeric, the medicinal food spice derived from Curcuma longa. The method uses iron-nitrilotriacetic acid (NTA)-agarose, to which curcumin binds rapidly, specifically, and reversibly. Curcumin, demethoxycurcumin, and bisdemethoxycurcumin each bound iron-NTA-agarose with comparable affinities and a stoichiometry near 1. Analyses of binding efficiencies and purity demonstrated that curcuminoids comprise the primary iron binding compounds recovered from a crude turmeric extract. Competition of curcuminoid binding to the iron resin was used to characterize the metal binding site on curcumin and to detect iron binding by added chelators. Curcumin-Iron-NTA-agarose binding was inhibited by other metals with relative potency: (>90% inhibition) Cu 2+  ~ Al 3+  > Zn 2+  ≥ Ca 2+  ~ Mg 2+  ~ Mn 2+ (<20% inhibition). Binding was also inhibited by pharmaceutical iron chelators (desferoxamine or EDTA) or by higher concentrations of weak iron chelators (citrate or silibinin). Investigation of the physiological effects of iron binding by curcumin revealed that curcumin uptake by cultured cells was reduced >80% by addition of iron to the media; uptake was completely restored by desferoxamine. Ranking of metals by relative potencies for blocking curcumin uptake agreed with their relative potencies in blocking curcumin binding to iron-NTA-agarose. We conclude that curcumin can selectively bind toxic metals including iron in a physiological setting, and propose inhibition of curcumin binding to iron-NTA-agarose for iron chelator screening.

Beneficial effects of humic acid on micronutrient availability to wheat

NASA Technical Reports Server (NTRS)

Mackowiak, C. L.; Grossl, P. R.; Bugbee, B. G.

2001-01-01

Humic acid (HA) is a relatively stable product of organic matter decomposition and thus accumulates in environmental systems. Humic acid might benefit plant growth by chelating unavailable nutrients and buffering pH. We examined the effect of HA on growth and micronutrient uptake in wheat (Triticum aestivum L.) grown hydroponically. Four root-zone treatments were compared: (i) 25 micromoles synthetic chelate N-(4-hydroxyethyl)ethylenediaminetriacetic acid (C10H18N2O7) (HEDTA at 0.25 mM C); (ii) 25 micromoles synthetic chelate with 4-morpholineethanesulfonic acid (C6H13N4S) (MES at 5 mM C) pH buffer; (iii) HA at 1 mM C without synthetic chelate or buffer; and (iv) no synthetic chelate or buffer. Ample inorganic Fe (35 micromoles Fe3+) was supplied in all treatments. There was no statistically significant difference in total biomass or seed yield among treatments, but HA was effective at ameliorating the leaf interveinal chlorosis that occurred during early growth of the nonchelated treatment. Leaf-tissue Cu and Zn concentrations were lower in the HEDTA treatment relative to no chelate (NC), indicating HEDTA strongly complexed these nutrients, thus reducing their free ion activities and hence, bioavailability. Humic acid did not complex Zn as strongly and chemical equilibrium modeling supported these results. Titration tests indicated that HA was not an effective pH buffer at 1 mM C, and higher levels resulted in HA-Ca and HA-Mg flocculation in the nutrient solution.

New Synthetic Approach for the Incorporation of 3,2-Hydroxypyridinone (HOPO) Ligands: Synthesis of Structurally Diverse Poly HOPO Chelators

PubMed Central

Arumugam, Jayanthi; Brown, Hayley A.; Jacobs, Hollie K.; Gopalan, Aravamudan S.

2011-01-01

The HOPO sulfonamide reagent, 3, was prepared from commercial 2,3-dihydroxypyridine in four steps in good yields. Sulfonamide 3 readily underwent selective alkylation with dibromides in the presence of base or could be coupled to alcohols using Mitsunobu conditions. The utility of this nucleophilic HOPO reagent was demonstrated by the synthesis some tris and tetraHOPO chelators. This approach for tethering HOPO ligands is unique and flexible as shown by the preparation of HOPO/iminocarboxylic acid chelator 17. PMID:21709749

Acid leaching of natural chrysotile asbestos to mesoporous silica fibers

NASA Astrophysics Data System (ADS)

Maletaškić, Jelena; Stanković, Nadežda; Daneu, Nina; Babić, Biljana; Stoiljković, Milovan; Yoshida, Katsumi; Matović, Branko

2018-04-01

Nanofibrous silica with a high surface area was produced from chrysotile by the acid-leaching method. Natural mineral chrysotile asbestos from Stragari, Korlace in Serbia was used as the starting material. The fibers were modified by chemical treatment with 1 M HCl and the mineral dissolution was monitored by transmission electron microscopy, X-ray powder diffraction, inductively coupled plasma spectrometry and low-temperature nitrogen adsorption techniques to highlight the effects of the leaching process. The results showed that the applied concentration of acid solution and processing time of 4 h were sufficient to effectively remove the magnesium hydroxide layer and transform the crystal structure of the hazardous starting chrysotile to porous SiO2 nanofibers. With prolonged acid leaching, the specific surface area, S BET, calculated by BET equation, was increased from 147 up to 435 m2 g- 1, with micropores representing a significant part of the specific surface.

Improving the efficiency of phytoremediation using electrically charged plant and chelating agents.

PubMed

Tahmasbian, Iman; Safari Sinegani, Ali Akbar

2016-02-01

The low efficiency of phytoremediation is a considerable problem that limits the application of this environmentally friendly method on heavy metal-polluted soils. The combination of chelate-assisted phytoextraction and electrokinetic remediation could offer new opportunities to improve the effectiveness of phytoextraction. The current experiment aims to investigate the effects of electrical fields and chelating agents on phytoremediation efficiency. In a pot experiment using mine soil, poultry manure extract (PME), cow manure extract (CME), and ethylenediaminetetraacetic acid (EDTA) were applied to soil as chelating agents (2 g kg(-1)) at the beginning of the flowering stage. A week later, Helianthus annuus (sunflower) was negatively charged by inserting a stainless steel needle with 10 and 30 V DC electricity in the lowest part of the stems for 1 h each day for a 14-day period. At the end of the experiment, the shoot and root dry weight, lead (Pb) concentration in plant organs, translocation factor (TF), metal uptake index (UI), and soil available Pb (diethylene triamine pentaacetic acid (DTPA) extractable) were detected. Results indicated that the application of electrical fields had no significant impact on the shoot and root dry weights, while Pb concentration and UI increased in the 10-V EDTA treatment by 500 % compared to control. There was no significant difference between UI in 30- and 10-V EDTA treatments. Soil available Pb significantly increased in the 30-V treated soil. A positive correlation was observed between the available Pb in soil near the root and Pb concentration in shoot, its TF, and UI. In conclusion, a negatively charged plant along with the application of EDTA significantly increased the phytoremediation efficiency.

Luminescent Properties of Eu(III) Chelates on Metal Nanorods

PubMed Central

Zhang, Jian; Fu, Yi; Ray, Krishanu; Wang, Yuan; Lakowicz, Joseph. R.

2013-01-01

In this article, we report the change of optical properties for europium chelates on silver nanorods by near-field interactions. The silver rods were fabricated in a seed-growth method followed by depositing thin layers of silica on the surfaces. The europium chelates were physically absorbed in the silica layers on the silver rods. The silver rods were observed to exhibit two plasmon absorption bands from longitudinal and transverse directions, respectively, centered at 394 and 675 nm, close to absorption and emission bands from the Eu(III) chelates. As a result, the immobilized Eu(III) chelates on the silver rods should have strong interactions with the silver nanorods and lead to greatly improved optical properties. The Eu–Ag rod complexes were observed to have enhanced emission intensity up to 240-fold in comparison with the Eu(III) chelates in the metal-free silica templates. This enhancement is much larger than the value for the Eu(III) chelates on the gold rods or silver spheres indicating the presence of stronger interactions for the Eu(III) chelates with the silver rods. The interactions of Eu(III) chelates with the silver rods were also proven by extremely reduced lifetime. Moreover, the Eu–Ag rod complexes exhibited a polarized emission, which was also due to strong interactions of the Eu(III) chelates with the silver rods. All of these features may promise that the Eu(III)–Ag rod complexes have great potential for use as fluorescence imaging agents in biological assays. PMID:24363816

Spectroscopic properties and Judd-Ofelt theory analysis of erbium chelates.

PubMed

Wang, Huaishan; Qian, Guodong; Wang, Zhiyu; Wang, Minquan

2005-11-01

Erbium chelates including tris(acetylacetonato) erbium(III) monohydrate, tris(acetylacetonato)(1,10-phenanthroline) erbium(III) and tris(trifluoroacetylacetonato)(1,10-phenanthroline) erbium(III) are synthesized. Judd-Ofelt theory is employed on basis of the UV-Vis-NIR absorption spectra of erbium chelates dissolved in methanol. Judd-Ofelt parameters of erbium chelates are determined by a least square fitting and dealt with the chemical structure of erbium chelates. Photoluminescence characteristics of erbium chelates are investigated upon excitation at 488 nm by an Ar(+) laser. The qualitative correlation of Judd-Ofelt parameters with photoluminescence properties for erbium chelates is also discussed. It is found that larger Omega(6) value for erbium chelate is and larger photoluminescence intensity at 1.54 microm is, and Omega(2) value should contribute to the photoluminescence full width at half maximum (FWHM) at 1.54 microm. The changes of Judd-Ofelt parameters result from the introduction of the second ligand phenathroline or the substitution of electron-drawing group CF(3) in beta-diketone for erbium chelates.

Correlating Detergent Fiber Analysis and Dietary Fiber Analysis Data for Corn Stover

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wolfrum, E. J.; Lorenz, A. J.; deLeon, N.

There exist large amounts of detergent fiber analysis data [neutral detergent fiber (NDF), acid detergent fiber (ADF), acid detergent lignin (ADL)] for many different potential cellulosic ethanol feedstocks, since these techniques are widely used for the analysis of forages. Researchers working in the area of cellulosic ethanol are interested in the structural carbohydrates in a feedstock (principally glucan and xylan), which are typically determined by acid hydrolysis of the structural fraction after multiple extractions of the biomass. These so-called dietary fiber analysis methods are significantly more involved than detergent fiber analysis methods. The purpose of this study was to determinemore » whether it is feasible to correlate detergent fiber analysis values to glucan and xylan content determined by dietary fiber analysis methods for corn stover. In the detergent fiber analysis literature cellulose is often estimated as the difference between ADF and ADL, while hemicellulose is often estimated as the difference between NDF and ADF. Examination of a corn stover dataset containing both detergent fiber analysis data and dietary fiber analysis data predicted using near infrared spectroscopy shows that correlations between structural glucan measured using dietary fiber techniques and cellulose estimated using detergent techniques, and between structural xylan measured using dietary fiber techniques and hemicellulose estimated using detergent techniques are high, but are driven largely by the underlying correlation between total extractives measured by fiber analysis and NDF/ADF. That is, detergent analysis data is correlated to dietary fiber analysis data for structural carbohydrates, but only indirectly; the main correlation is between detergent analysis data and solvent extraction data produced during the dietary fiber analysis procedure.« less

Lead toxicosis of captive vultures: case description and responses to chelation therapy

PubMed Central

2013-01-01

Background Lead, a serious threat for raptors, can hamper the success of their conservation. This study reports on experience with accidental lead intoxication and responses to chelation therapy in captive Cinereous (Aegypius monachus) and Egyptian (Neophron percnopterus) Vultures. Results Soil contamination by lead-based paint sanded off the steel aviary resulted in poisoning of eight Cinereous and two Egyptian Vultures. A male Egyptian Vulture developed signs of apathy, polydipsia, polyuria, regurgitation, and stupor, and died on the next day. Liver, kidney and blood lead concentrations were 12.2, 8.16 and 2.66 μg/g, respectively. Laboratory analyses confirmed severe liver and kidney damage and anaemia. Blood Pb levels of Pb-exposed Cinereous Vultures were 1.571 ± 0.510 μg/g shortly after intoxication, decreased to 0.530 ± 0.165 μg/g without any therapy in a month and to 0.254 ± 0.097 μg/g one month after CaNa2EDTA administration. Eight months later, blood lead levels decreased to close to the background of the control group. Blood parameters of healthy Pb-non-exposed Cinereous Vultures were compared with those of the exposed group prior to and after chelation therapy. Iron levels in the lead-exposed pre-treatment birds significantly decreased after chelation. Haematocrit levels in Pb-exposed birds were significantly lower than those of the controls and improved one month after chelation. Creatine kinase was higher in pre-treatment birds than in the controls but normalised after therapy. Alkaline phosphatase increased after chelation. A marked increase in the level of lipid peroxidation measured as thiobarbituric acid reactive species was demonstrated in birds both prior to and after chelation. The ferric reducing antioxidant power was significantly lower in pre-treatment vultures and returned to normal following chelation therapy. Blood metallothionein levels in lead-exposed birds were higher than in controls. Reduced glutathione dropped after

Lead toxicosis of captive vultures: case description and responses to chelation therapy.

PubMed

Pikula, Jiri; Hajkova, Pavlina; Bandouchova, Hana; Bednarova, Ivana; Adam, Vojtech; Beklova, Miroslava; Kral, Jiri; Ondracek, Karel; Osickova, Jitka; Pohanka, Miroslav; Sedlackova, Jana; Skochova, Hana; Sobotka, Jakub; Treml, Frantisek; Kizek, Rene

2013-01-16

Lead, a serious threat for raptors, can hamper the success of their conservation. This study reports on experience with accidental lead intoxication and responses to chelation therapy in captive Cinereous (Aegypius monachus) and Egyptian (Neophron percnopterus) Vultures. Soil contamination by lead-based paint sanded off the steel aviary resulted in poisoning of eight Cinereous and two Egyptian Vultures. A male Egyptian Vulture developed signs of apathy, polydipsia, polyuria, regurgitation, and stupor, and died on the next day. Liver, kidney and blood lead concentrations were 12.2, 8.16 and 2.66 μg/g, respectively. Laboratory analyses confirmed severe liver and kidney damage and anaemia. Blood Pb levels of Pb-exposed Cinereous Vultures were 1.571 ± 0.510 μg/g shortly after intoxication, decreased to 0.530 ± 0.165 μg/g without any therapy in a month and to 0.254 ± 0.097 μg/g one month after CaNa(2)EDTA administration. Eight months later, blood lead levels decreased to close to the background of the control group. Blood parameters of healthy Pb-non-exposed Cinereous Vultures were compared with those of the exposed group prior to and after chelation therapy. Iron levels in the lead-exposed pre-treatment birds significantly decreased after chelation. Haematocrit levels in Pb-exposed birds were significantly lower than those of the controls and improved one month after chelation. Creatine kinase was higher in pre-treatment birds than in the controls but normalised after therapy. Alkaline phosphatase increased after chelation. A marked increase in the level of lipid peroxidation measured as thiobarbituric acid reactive species was demonstrated in birds both prior to and after chelation. The ferric reducing antioxidant power was significantly lower in pre-treatment vultures and returned to normal following chelation therapy. Blood metallothionein levels in lead-exposed birds were higher than in controls. Reduced glutathione dropped after CaNa(2)EDTA therapy, while

Obligatory reduction of ferric chelates in iron uptake by soybeans.

PubMed

Chaney, R L; Brown, J C; Tiffin, L O

1972-08-01

The contrasting Fe(2+) and Fe(3+) chelating properties of the synthetic chelators ethylenediaminedi (o-hydroxyphenylacetate) (EDDHA) and 4,7-di(4-phenylsulfonate)-1, 10-phenanthroline (bathophenanthrolinedisulfonate) (BPDS) were used to determine the valence form of Fe absorbed by soybean roots supplied with Fe(3+)-chelates. EDDHA binds Fe(3+) strongly, but Fe(2+) weakly; BPDS binds Fe(2+) strongly but Fe(3+) weakly. Addition of an excess of BPDS to nutrient solutions containing Fe(3+)-chelates inhibited soybean Fe uptake-translocation by 99+%; [Fe(II) (BPDS)(3)](4-) accumulated in the nutrient solution. The addition of EDDHA caused little or no inhibition. These results were observed with topped and intact soybeans. Thus, separation and absorption of Fe from Fe(3+)-chelates appear to require reduction of Fe(3+)-chelate to Fe(2+)-chelate at the root, with Fe(2+) being the principal form of Fe absorbed by soybean.

Preparation of Cotton-Wool-Like Poly(lactic acid)-Based Composites Consisting of Core-Shell-Type Fibers

PubMed Central

Wang, Jian; Zhou, Pin; Obata, Akiko; Jones, Julian R.; Kasuga, Toshihiro

2015-01-01

In previous works, we reported the fabrication of cotton-wool-like composites consisting of siloxane-doped vaterite and poly(l-lactic acid) (SiVPCs). Various irregularly shaped bone voids can be filled with the composite, which effectively supplies calcium and silicate ions, enhancing the bone formation by stimulating the cells. The composites, however, were brittle and showed an initial burst release of ions. In the present work, to improve the mechanical flexibility and ion release, the composite fiber was coated with a soft, thin layer consisting of poly(d,l-lactic-co-glycolic acid) (PLGA). A coaxial electrospinning technique was used to prepare a cotton-wool-like material comprising “core-shell”-type fibers with a diameter of ~12 µm. The fibers, which consisted of SiVPC coated with a ~2-µm-thick PLGA layer, were mechanically flexible; even under a uniaxial compressive load of 1.5 kPa, the cotton-wool-like material did not exhibit fracture of the fibers and, after removing the load, showed a ~60% recovery. In Tris buffer solution, the initial burst release of calcium and silicate ions from the “core-shell”-type fibers was effectively controlled, and the ions were slowly released after one day. Thus, the mechanical flexibility and ion-release behavior of the composites were drastically improved by the thin PLGA coating. PMID:28793691

Phytoremediation of metals contaminated dredged sediments: Use of synthetic chelates in metals phytoextraction

NASA Astrophysics Data System (ADS)

Sahut, C.; Geniaut, G.; Lillo, M. P.

2003-05-01

(in Times 10 points) The waterways maintenance leads to a large volume of dredged polluted sediments, to be disposed of, every year. As the economic disposal of dredged sediment is a single line along the stream they can behave as a sink of pollutant and a migration in the environment is observed. Chelate-enhanced phytoremediation has been proposed as an effective tool for the extraction of heavy metals from dredged sediment by plants. Lysimeters studies were conducted to study the phytoremediation of sediments with EDTA and lactic acid used as synthetic chelators. EDTA appeared to enhance metal solubility by plant uptake did not increase accordingly. Futhermore EDTA enhance metal leaching which could lead 10 groungwater pollution. To prevent these unwanted side-effects, careful management of phytoremediation and of the use of EDTA seems necessary.

Chelators whose affinity for calcium is decreased by illumination

NASA Technical Reports Server (NTRS)

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

1987-01-01

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

Detection of glycoprotein using fiber optic surface plasmon resonance sensors with boronic acid

NASA Astrophysics Data System (ADS)

Wang, Fang; Zhang, Yang; Liu, Zigeng; Qian, Siyu; Gu, Yiying; Jing, Zhenguo; Sun, Changsen; Peng, Wei

2017-04-01

In this paper, we present a tilted fiber Bragg gratings (TFBG) based surface Plasmon resonance (SPR) label-free sensors with boronic acid derivative (ABA-PBA) as receptor molecule to detect glycoprotein with high sensitivity and selectivity. Tilted fiber Bragg gratings (TFBG) as a near infrared wavelengths detecting element can be able to excite a number of cladding modes whose properties can be detected accurately by measuring the variation of transmitted spectra. A 10° TFBG coated by 50nm gold film was manufactured to stimulate surface plasmon resonance on the surface of the sensor. The sensor was loaded with boronic acid derivative as the recognition molecule which has been widely used in various areas for the recognition matrix of diol-containing biomolecules. The proposed TFBG-SPR sensors exhibit good selectivity and repeatability with the protein concentration sensitivity up to 2.867dB/ (mg/ml) and the limit of detection was 2*10-5g/ml.

Effects of dietary fiber on cecal short-chain fatty acid and cecal microbiota of broiler and laying-hen chicks.

PubMed

Walugembe, M; Hsieh, J C F; Koszewski, N J; Lamont, S J; Persia, M E; Rothschild, M F

2015-10-01

This experiment was conducted to evaluate the effects of feeding dietary fiber on cecal short-chain fatty acid (SCFA) concentration and cecal microbiota of broiler and laying-hen chicks. The lower fiber diet was based on corn-soybean meal (SBM) and the higher fiber diet was formulated using corn-SBM-dried distillers grains with solubles (DDGS) and wheat bran to contain 60.0 g/kg of both DDGS and wheat bran from 1 to 12 d and 80.0 g/kg of both DDGS and wheat bran from 13 to 21 d. Diets were formulated to meet or exceed NRC nutrient requirements. Broiler and laying-hen chicks were randomly assigned to the high and low fiber diets with 11 replicates of 8 chicks for each of the 4 treatments. One cecum from 3 chicks was collected from each replicate: one cecum underwent SCFA concentration analysis, one underwent bacterial DNA isolation for terminal restriction fragment length polymorphism (TRFLP), and the third cecum was used for metagenomics analyses. There were interactions between bird line and dietary fiber for acetic acid (P = 0.04) and total SCFA (P = 0.04) concentration. There was higher concentration of acetic acid (P = 0.02) and propionic acid (P < 0.01) in broiler chicks compared to laying-hen chicks. TRFLP analysis showed that cecal microbiota varied due to diet (P = 0.02) and chicken line (P = 0.03). Metagenomics analyses identified differences in the relative abundance of Helicobacter pullorum and Megamonas hypermegale and the genera Enterobacteriaceae, Campylobacter, Faecalibacterium, and Bacteroides in different treatment groups. These results provide insights into the effect of dietary fiber on SCFA concentration and modulation of cecal microbiota in broiler and laying-hen chicks. © 2015 Poultry Science Association Inc.

An Evaluation of Peripapillary Retinal Nerve Fiber Layer Thickness in Children With Epilepsy Receiving Treatment of Valproic Acid.

PubMed

Dereci, Selim; Koca, Tuğba; Akçam, Mustafa; Türkyilmaz, Kemal

2015-07-01

We investigated the peripapillary retinal nerve fiber layer thickness with optical coherence tomography in epileptic children receiving valproic acid monotherapy. The study was conducted on children aged 8-16 years who were undergoing valproic acid monotherapy for epilepsy. The study group comprised a total of 40 children who met the inclusion criteria and 40 healthy age- and sex-matched children as a control group. Children with at least a 1-year history of epilepsy and taking 10-40 mg/kg/day treatment were included in the study. Peripapillary retinal nerve fiber layer thickness measurements were performed using Cirrus HD optical coherence tomography. All children and parents were informed about the study and informed consent was obtained from the parents of all the participants. The study group included 21 girls and 19 boys with a mean age of 10.6 ± 2.3 years. According to the results of optical coherence tomography measurements, the mean peripapillary retinal nerve fiber layer thickness was 91.6 ± 9.7 in the patient group and 95.5 ± 7.4 μm in the control group (P < 0.05). The superior peripapillary retinal nerve fiber layer thickness was 112.0 ± 13.2 in the patient group and 120.0 ± 14.7 μm in the control group (P < 0.02). According to the results of both measurements, the peripapillary retinal nerve fiber layer thickness was significantly lower in the patient group. Neither color vision loss nor visual field examination abnormality could be documented. According to the optical coherence tomography measurements, the average and superior peripapillary retinal nerve fiber layer thicknesses were thinner in patients with epilepsy who were receiving valproic acid monotherapy compared with healthy children. This situation can lead to undesirable results in terms of eye health. New studies are needed to investigate whether these findings are the result of epilepsy or can be attributed to valproic acid and whether there are adverse effects of

Role of different chelating agent in synthesis of copper doped tin oxide (Cu-SnO2) nanoparticles

NASA Astrophysics Data System (ADS)

Saravanakumar, B.; Anusiya, A.; Rani, B. Jansi; Ravi, G.; Yuvakkumar, R.

2018-05-01

An attempt was made to synthesis the copper doped tin oxide (Cu-SnO2) nanoparticles by adopting different chelating agents (NaOH, KOH and C2H2O4) by Sol-gel process. The synthesized products were characterized by XRD, Photoluminescence (PL), Infra- Red (FTIR) and SEM analysis. The XRD confirms the formation of Cu-SnO2 shows the maximum peak at 33.8° with lattice plane (101). The PL peak at 361 and 382 nm due to the recombination of electron in conduction band to valence band infers the optical properties. The IR spectra correspond to the peak at 551 and 620 cm-1 attributed to the characteristics peak for Cu-SnO2 nanoparticles. The SEM images for all three Cu-SnO2 nanoparticles formed by three chelating agent (NaOH, KOH and C2H2O4) facilitates the formation mechanism and the chelating agent Oxalic acid results in formation of nano flowers with diverse layers orientated in random direction. Further SEM studies reveal that, the Cu-SnO2 nanoparticles formed by oxalic acid could posses high surface area with large number layered structured enables the better electrochemical properties and its applications.

Electrospinning of Polyaniline/Poly(Lactic Acid) Ultrathin Fibers: Process and Statistical Modeling using a Non-Gaussian Approach

USDA-ARS?s Scientific Manuscript database

Fibers of poly(lactic acid) (PLA) blended with p-toluenesulfonic acid-doped polyaniline, PAni.TSA, were obtained by lectrospinning, following a factorial design which was used mainly to study the effect of four process parameters (PLA solution concentration, PAni solution concentration, applied volt...

Lanthanide-binding peptides with two pendant aminodiacetate arms: impact of the sequence on chelation.

PubMed

Niedźwiecka, Agnieszka; Cisnetti, Federico; Lebrun, Colette; Gateau, Christelle; Delangle, Pascale

2012-03-21

Lanthanide complexes with a series of hexapeptides-incorporating two unnatural chelating amino acids with aminodiacetate groups, Ada(1) and Ada(2)-have been examined in terms of their speciation, structure, stability and luminescence properties. Whereas Ada(2) acts as a tridentate donor in all cases, Ada(1) may act as a tetradentate donor thanks to the coordination of the amide carbonyl function assisted by the formation of a six-membered chelate ring. The position of the Ada(1) residue in the sequence is demonstrated to be critical for the lanthanide complex speciation and structure. Ada(1) promotes the coordination of the backbone amide function to afford a highly dehydrated Ln complex and an S-shape structure of the peptide backbone, only when found in position 2.

Behavior of human immunoglobulin G adsorption onto immobilized Cu(II) affinity hollow-fiber membranes.

PubMed

Borsoi-Ribeiro, Mariana; Bresolin, Igor Tadeu Lazzarotto; Vijayalakshmi, Mookambeswaran; Bueno, Sônia Maria Alves

2013-10-01

Iminodiacetic acid (IDA) and tris(2-aminoethyl)amine (TREN) chelating ligands were immobilized on poly(ethylene vinyl alcohol) (PEVA) hollow-fiber membranes after activation with epichlorohydrin or butanediol diglycidyl ether (bisoxirane). The affinity membranes complexed with Cu(II) were evaluated for adsorption of human immunoglobulin G (IgG). The effects of matrix activation and buffer system on adsorption of IgG were studied. Isotherms of batch IgG adsorption onto finely cut membranes showed that neither of the chelates, IDA-Cu(II) or TREN-Cu(II), had a Langmuirean behavior with negative cooperativity for IgG binding. A comparison of equilibrium and dynamic maximum capacities showed that the dynamic capacity for a mini-cartridge in a cross-flow filtration mode (52.5 and 298.4 mg g(-1) dry weight for PEVA-TREN-Cu(II) and PEVA-IDA-Cu(II), respectively) was somewhat higher than the equilibrium capacity (9.2 and 73.3 mg g(-1) dry weight for PEVA-TREN-Cu(II) and PEVA-IDA-Cu(II), respectively). When mini-cartridges were used, the dynamic adsorption capacity of IDA-Cu(II) was the same for both mini-cartridge and agarose gel. Copyright © 2013 John Wiley & Sons, Ltd.

Chlorogenic acid protects against aluminium-induced cytotoxicity through chelation and antioxidant actions in primary hippocampal neuronal cells.

PubMed

Wang, Xiaomei; Fan, Xinguang; Yuan, Shuzhi; Jiao, Wenxiao; Liu, Bangdi; Cao, Jiankang; Jiang, Weibo

2017-08-01

Chlorogenic acid (CGA), a major polyphenolic component of many plants, displays antioxidant and neuroprotective properties in neurodegenerative diseases. To investigate whether CGA may influence aluminium (Al) induced cytotoxicity, aluminium chloride (50 μM Al) was administered in primary hippocampal neuronal cells presupplemented with CGA (10, 50 and 100 μM). Our study shows that the exposure to Al caused cell death, Al 3+ accumulation, reactive oxygen species generation and mitochondrial damage in cells. The administration of CGA (50 μM) increased cell viability by 37.5%, decreased the levels of Al 3+ by 26.0%, together with significantly weakening the oxidative damage compared with Al treatment alone. CGA protected neurons against Al-induced oxidative stress by increasing the expression of nuclear factor-E2-related factor 2 and its target phase 2 enzymes. The administration of CGA remarkably promoted the activities of superoxide dismutase, catalase, glutathione peroxidase, glutathione S-transferase, creatine kinase and acetylcholinesterase and attenuated the rate of ATP hydrolysis. Our finding shows that CGA has neuroprotective effects against Al-induced cytotoxicity by chelation and antioxidant activation.

Potential toxicity of nonregulated asbestiform minerals: balangeroite from the western Alps. Part 2: Oxidant activity of the fibers.

PubMed

Turci, Francesco; Tomatis, Maura; Gazzano, Elena; Riganti, Chiara; Martra, Gianmario; Bosia, Amalia; Ghigo, Dario; Fubini, Bice

2005-01-08

The asbestiform mineral balangeroite [(Mg,Fe2+,Fe3+,Mn2+)42Si16O54(OH)36], whose toxic potential is unknown, is associated with chrysotile asbestos in the western Alps (Balangero mine, Piedmont, Italy). In order to examine whether such fibers may contribute to the oxidative damage produced by local asbestos dusts when inhaled, balangeroite was studied by means of both cell-free and cellular tests, comparing the results with those concerning the most pathogenic asbestos form, crocidolite. Similarly to the crocidolite surface, iron was mobilized from balangeroite by chelators, to a different extent: deferoxamine > ascorbic acid > ferrozine. Poorly coordinated surface ions, as evaluated from the adsorption of NO as a probe molecule (by both calorimetry and infrared spectroscopy), are even more abundant on balangeroite than on crocidolite. The spin trapping technique shows that surface iron-derived Fenton activity (HO* from H2O2) is similar for the two fiber types, while a pretreatment in ascorbic acid, by reducing previously oxidized surface iron, activates the potential to cleave a C-H bond (yielding *CO2- from formate anion). Balangeroite, like crocidolite, produces nitrite accumulation, lipid peroxidation, and NO synthase activation in a human lung epithelial cell line (A549). All these findings, regarded as features related to the toxic potential of asbestos, suggest that balangeroite may be a potentially hazardous fiber per se and could be partly responsible for lung diseases reported in epidemiological studies in exposed miners.

Inhibition of Pseudomonas aeruginosa biofilm formation by 2,2'-bipyridyl, lipoic, kojic and picolinic acids.

PubMed

Çevik, Kübra; Ulusoy, Seyhan

2015-08-01

The inhibitory effects of iron chelators, and FeCl3 chelation on biofilm formation and swarming motility were investigated against an opportunistic human pathogen Pseudomonas aeruginosa. The inhibitory activity of 2,2'-bipyridyl, lipoic acid, kojic acid and picolinic acid on biofilm formation of P. aeruginosa strain PAO1 and three clinical isolates (P. aeruginosa PAK01, P. aeruginosa PAK02 and P. aeruginosa PAK03) were investigated, based on crystal violet assay, and swarming motility test. The kojic, lipoic and picolinic acid inhibited biofilm formation by 5-33% in all tested P. aeruginosa isolates. When chelated iron was added, biofilm inhibition rates were determined to be 39-57%. Among the tested chelators against P. aeruginosa, lipoic acid (84%) and kojic acid (68%) presented the highest inhibition of swarming motility. This is the first study to report the inhibitory effect of lipoic acid on biofilm formation and swarming motility of P. aeruginosa. It is considered that lipoic and picolinic acids can serve as alternatives for the treatment of the P. aeruginosa infections by inhibiting biofilm formation.

Development of Poly(lactic acid)/Chitosan Fibers Loaded with Essential Oil for Antimicrobial Applications

PubMed Central

Liu, Yaowen; Wang, Shuyao; Zhang, Rong; Lan, Wenting; Qin, Wen

2017-01-01

Cinnamon essential oil (CEO) was successfully encapsulated into chitosan (CS) nanoparticles at different loading amounts (1%, 1.5%, 2%, and 2.5% v/v) using oil-in-water (o/w) emulsion and ionic-gelation methods. In order to form active packaging, poly(lactic acid) (PLA) was used to fabricate PLA/CS-CEO composite fibers using a simple electrospinning method. The shape, size, zeta potential, and encapsulation efficacy of the CS-CEO nanoparticles were investigated. The composition, morphology, and release behavior of the composite fibers were investigated. PLA/CS-CEO-1.5 showed good stability and favorable sustained release of CEO, resulting in improved antimicrobial activity compared to the other blends. The PLA/CS-CEO fibers showed high long-term inactivation rates against Escherichia coli and Staphylococcus aureus due to the sustained release of CEO, indicating that the developed PLA/CS-CEO fibers have great potential for active food packaging applications. PMID:28737719

Succinic acid production by Actinobacillus succinogenes using hydrolysates of spent yeast cells and corn fiber.

PubMed

Chen, Ke-Quan; Li, Jian; Ma, Jiang-Feng; Jiang, Min; Wei, Ping; Liu, Zhong-Min; Ying, Han-Jie

2011-01-01

The enzymatic hydrolysate of spent yeast cells was evaluated as a nitrogen source for succinic acid production by Actinobacillus succinogenes NJ113, using corn fiber hydrolysate as a carbon source. When spent yeast cell hydrolysate was used directly as a nitrogen source, a maximum succinic acid concentration of 35.5 g/l was obtained from a glucose concentration of 50 g/l, with a glucose utilization of 95.2%. Supplementation with individual vitamins showed that biotin was the most likely factor to be limiting for succinic acid production with spent yeast cell hydrolysate. After supplementing spent yeast cell hydrolysate and 90 g/l of glucose with 150 μg/l of biotin, cell growth increased 32.5%, glucose utilization increased 37.6%, and succinic acid concentration was enhanced 49.0%. As a result, when biotin-supplemented spent yeast cell hydrolysate was used with corn fiber hydrolysate, a succinic acid yield of 67.7% was obtained from 70.3 g/l of total sugar concentration, with a productivity of 0.63 g/(l h). Our results suggest that biotin-supplemented spent yeast cell hydrolysate may be an alternative nitrogen source for the efficient production of succinic acid by A. succinogenes NJ113, using renewable resources. Crown Copyright © 2010. Published by Elsevier Ltd. All rights reserved.

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

PubMed

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. Copyright © 2016 Elsevier B.V. All rights reserved.

Jacks of metal/metalloid chelation trade in plants—an overview

PubMed Central

Anjum, Naser A.; Hasanuzzaman, Mirza; Hossain, Mohammad A.; Thangavel, Palaniswamy; Roychoudhury, Aryadeep; Gill, Sarvajeet S.; Rodrigo, Miguel A. Merlos; Adam, Vojtěch; Fujita, Masayuki; Kizek, Rene; Duarte, Armando C.; Pereira, Eduarda; Ahmad, Iqbal

2015-01-01

Varied environmental compartments including soils are being contaminated by a myriad toxic metal(loid)s (hereafter termed as “metal/s”) mainly through anthropogenic activities. These metals may contaminate food chain and bring irreparable consequences in human. Plant-based approach (phytoremediation) stands second to none among bioremediation technologies meant for sustainable cleanup of soils/sites with metal-contamination. In turn, the capacity of plants to tolerate potential consequences caused by the extracted/accumulated metals decides the effectiveness and success of phytoremediation system. Chelation is among the potential mechanisms that largely govern metal-tolerance in plant cells by maintaining low concentrations of free metals in cytoplasm. Metal-chelation can be performed by compounds of both thiol origin (such as GSH, glutathione; PCs, phytochelatins; MTs, metallothioneins) and non-thiol origin (such as histidine, nicotianamine, organic acids). This paper presents an appraisal of recent reports on both thiol and non-thiol compounds in an effort to shed light on the significance of these compounds in plant-metal tolerance, as well as to provide scientific clues for the advancement of metal-phytoextraction strategies. PMID:25883598

Chemical evaluation of HBED/Fe(3+) and the novel HJB/Fe(3+) chelates as fertilizers to alleviate iron chlorosis.

PubMed

López-Rayo, Sandra; Hernández, Diana; Lucena, Juan J

2009-09-23

Iron chelates such as ethylenediamine-N,N'-bis(2-hydroxyphenylacetic) acid (o,o-EDDHA) and their analogues are the most efficient soil fertilizers to treat iron chlorosis in plants growing in calcareous soil. A new chelating agent, HJB (N,N'-bis(2-hydroxy-5-methylphenyl)ethylendiamine-N,N'-diacetic acid) may be an alternative to o,o-EDDHA since its synthesis yields a purer product, but its chemical behavior and efficiency as chlorosis corrector should be evaluated. In this research, a known analogous HBED (N,N'-bis(2-hydroxyphenyl)ethylendiamine-N,N'-diacetic acid) has also been considered. First, an ion-pair high performance liquid chromatography (HPLC) method has been tested for the HJB/Fe(3+) and HBED/Fe(3+) determination. The ability of HJB and HBED to maintain Fe in solution has been compared with respect to o,o-EDDHA. Theoretical modelization for HBED and HJB in agronomic conditions has been done after the determination of the protonation and Ca(II), Mg(II), Fe(III), and Cu(II) stability constants for HJB. Also, batch interaction experiments with soils and soil materials have been conducted. According to our results, HJB/Fe(3+) and HBED/Fe(3+) present high stability, even when competing cations (Cu(2+), Ca(2+)) are present, and have low reactivity with soils and soil components. The chelating agent HJB dissolves a higher amount of Fe than o,o-EDDHA, and it seems as effective as o,o-EDDHA in keeping Fe in solution. These results indicate that these chelates may be very efficient products to correct Fe chlorosis, and additional plant experiments should demonstrate plants' ability to assimilate Fe from HJB/Fe(3+) and HBED/Fe(3+).

EDTA Chelation Therapy Alone and in Combination with Oral High-Dose Multivitamins and Minerals for Coronary Disease: The Factorial Group Results of the Trial to Assess Chelation Therapy

PubMed Central

Lamas, Gervasio A.; Boineau, Robin; Goertz, Christine; Mark, Daniel B.; Rosenberg, Yves; Stylianou, Mario; Rozema, Theodore; Nahin, Richard L.; Chappell, L. Terry; Lindblad, Lauren; Lewis, Eldrin F.; Drisko, Jeanne; Lee, Kerry L.

2014-01-01

Background Disodium ethylene diamine tetraacetic acid (EDTA) reduced adverse cardiac outcomes in a factorial trial also testing oral vitamins. Objective This report describes the intent-to-treat comparison of the 4 factorial groups overall and in patients with diabetes. Methods Double-blind placebo-controlled 2 × 2 factorial multicenter randomized trial of 1708 post-MI patients ≥ 50 years and creatinine ≤2.0 mg/dL randomized to receive 40 EDTA chelation or placebo infusions plus 6 caplets daily of a 28-component multivitaminmultimineral mixture or placebo. Primary endpoint was a composite of total mortality, MI, stroke, coronary revascularization, or hospitalization for angina. Results Median age was 65 years, 18% female, 94% Caucasian, 37% diabetic, 83% prior coronary revascularization, and 73% on statins. Five-year Kaplan-Meier estimates for the primary endpoint in the chelation + high-dose vitamin group was 31.9%, in the chelation + placebo vitamin group 33.7%, in the placebo infusion + active vitamin group 36.6%, and in the placebo infusions + placebo vitamin group 40.2 %. The reduction in primary endpoint by double active treatment compared with double placebo was significant (HR 0.74, 95% CI (0.57,0.95); p=0.016). In patients with diabetes, the primary endpoint reduction of double active compared with double placebo was more pronounced (HR 0.49, 95% CI (0.33,0.75), p<0.001). Conclusions In stable post- MI patients on evidence-based medical therapy, the combination of oral high-dose vitamins and chelation therapy compared with double placebo reduced clinically important cardiovascular events to an extent that was both statistically significant and of potential clinical relevance. PMID:24952858

Synthesis of o,p-EDDHA and its detection as the main impurity in o,o-EDDHA commercial iron chelates.

PubMed

Gómez-Gallego, Mar; Sierra, Miguel A; Alcázar, Roberto; Ramírez, Pedro; Piñar, Carmen; Mancheño, María José; García-Marco, Sonia; Yunta, Felipe; Lucena, Juan José

2002-10-23

Ethylenediamine-N,N'bis(o-hydroxyphenyl)acetic acid (o,o-EDDHA) is one of the most efficient iron chelates employed to relieve iron chlorosis in plants. However, the presence of positional isomers of EDDHA in commercial iron chelates has been recently demonstrated, and among them, it has been claimed that ethylenediamine-N(o-hydroxyphenylacetic)-N'(p-hydroxyphenylacetic) acid (o,p-EDDHA) is the main impurity present in EDDHA fertilizers. Here we report the preparation of o,p-EDDHA, a compound whose synthesis had not been previously reported. The synthetic o,p-EDDHA is able to form ferric complexes, and it has been used as a standard in the analysis of the impurities of commercial iron fertilizers. The presence of o,p-EDDHA/Fe(3+) in commercial samples has been unambiguously demonstrated by HPLC.

Effect of insoluble-low fermentable fiber from corn-ethanol distillation origin on energy, fiber, and amino acid digestibility, hindgut degradability of fiber, and growth performance of pigs.

PubMed

Gutierrez, N A; Kerr, B J; Patience, J F

2013-11-01

Extensive use of corn coproducts in swine diets increases the concentration of dietary fiber, raising concerns on energy and nutrient digestibility and, ultimately, pig performance. A digestion trial was conducted to determine the effect of increasing levels of insoluble-low fermentable fiber from corn in the diet, using corn bran with solubles (CBS) from the corn-ethanol distillation industry, on digestibility of energy, fiber, and AA, and hindgut fermentation of fiber in diets fed to growing pigs. Fifteen growing pigs (BW=28.7 kg) arranged in a 3-period incomplete block design and fitted with a T-cannula in the distal ileum were provided 5 diets (n=9) containing either a corn-casein basal or the basal diet with 10, 20, 30, or 40% CBS. Fecal and ileal digesta samples were collected. Two subsequent 28-d growth trials determined the effects of increasing dietary fiber from CBS in 2 sets of 7 diets formulated either with declining (growing phase: 2,387 to 2,133 kcal NE/kg; finishing phase: 2,499 to 2,209 kcal NE/kg) or constant dietary NE (growing phase≈2,390 kcal NE/kg; finishing phase≈2,500 kcal NE/kg) on growth performance and apparent total tract digestibility (ATTD) of energy in 70 growing (BW=48.9 kg; n=10 per diet) and 70 finishing (BW=102.0 kg; n=10) pigs. Results indicated that increasing fiber from corn lowered (P<0.01) the apparent ileal digestibility of all indispensable amino acids except Arg, GE, DM, and CP but not NDF or total dietary fiber (TDF). Increased fiber from corn also reduced ATTD of GE, DM, CP, NDF, and TDF (P<0.01). Increasing fiber with declining diet NE lowered BW, ADG, and G:F (P<0.05) in growing and in finishing pigs. When NE was held constant, as fiber increased, BW and ADG were unaffected in growing and finishing pigs, and G:F was unaffected in finishing pigs but improved in growing pigs (P<0.05) with increasing dietary fiber. In both growing and finishing pigs, ADFI was unaffected by the increased fiber from corn, regardless of

TCE degradation in groundwater by chelators-assisted Fenton-like reaction of magnetite: Sand columns demonstration.

PubMed

Jia, Daqing; Sun, Sheng-Peng; Wu, Zhangxiong; Wang, Na; Jin, Yaoyao; Dong, Weiyang; Chen, Xiao Dong; Ke, Qiang

2018-03-15

Trichloroethylene (TCE) degradation in sand columns has been investigated to evaluate the potential of chelates-enhanced Fenton-like reaction with magnetite as iron source for in situ treatment of TCE-contaminated groundwater. The results showed that successful degradation of TCE in sand columns was obtained by nitrilotriacetic acid (NTA)-assisted Fenton-like reaction of magnetite. Addition of ethylenediaminedisuccinic acid (EDDS) resulted in an inhibitory effect on TCE degradation in sand columns. Similar to EDDS, addition of ethylenediaminetetraacetic acid (EDTA) also led to an inhibition of TCE degradation in sand column with small content of magnetite (0.5 w.t.%), but enhanced TCE degradation in sand column with high content of magnetite (7.0 w.t.%). Additionally, the presence of NTA, EDDS and EDTA greatly decreased H 2 O 2 uptake in sand columns due to the competition between chelates and H 2 O 2 for surface sites on magnetite (and sand). Furthermore, the presented results show that magnetite in sand columns remained stable in a long period operation of 230 days without significant loss of performance in terms of TCE degradation and H 2 O 2 uptake. Moreover, it was found that TCE was degraded mainly to formic acid and chloride ion, and the formation of chlorinated organic intermediates was minimal by this process. Copyright © 2017 Elsevier B.V. All rights reserved.

Micronutrient metal speciation is controlled by competitive organic chelation in grassland soils

DOE PAGES

Boiteau, Rene M.; Shaw, Jared B.; Pasa-Tolic, Ljiljana; ...

2018-03-08

Many elements are scarcely soluble in aqueous conditions found in high pH environments, such as calcareous grassland soils, unless complexed to strong binding organic ligands. To overcome this limitation, some plants and microbes produce chelators that solubilize micronutrient metals such as Fe, Ni, Cu, and Zn from mineral phases. These complexes are taken up by organisms via specific membrane receptors, thereby differentially impacting the bioavailability of these metals to the plant and microbial community. Although the importance of these chelation strategies for individual organisms has been well established, little is known about which pathways coexist within rhizosphere microbiomes or howmore » they interact and compete for metal binding. Identifying these metallophores within natural ecosystems has remained a formidable analytical challenge due to the vast diversity of compounds and poorly defined metabolic processes in complex soil matrices. Herein, we employed recently developed liquid chromatography (LC) mass spectrometry (MS) methods to characterize the speciation of water-soluble dissolved trace elements (Fe, Ni, Cu, and Zn) of soils from native tallgrass prairies in Kansas and Iowa. Both plant and fungal metallophores were identified, revealing compound-specific patterns of chelation to biologically essential metals. Numerous metabolites typically implicated in plant Fe acquisition and homeostasis, including mugineic acids, deoxymugineic acid, nicotianamine, and hydroxynicotianamines, dominated the speciation of divalent metals such as Ni, Cu, and Zn (2–90 pmol/g soil). In contrast, the fungal siderophore ferricrocin was specific for trivalent Fe (7–32 pmol/g soil). These results define biochemical pathways that underpin the regulation of metals in the grassland rhizosphere. They also raise new questions about the competition of these compounds for metal binding and their bioavailability to different members of the rhizosphere population. In

Micronutrient metal speciation is controlled by competitive organic chelation in grassland soils

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boiteau, Rene M.; Shaw, Jared B.; Pasa-Tolic, Ljiljana

Many elements are scarcely soluble in aqueous conditions found in high pH environments, such as calcareous grassland soils, unless complexed to strong binding organic ligands. To overcome this limitation, some plants and microbes produce chelators that solubilize micronutrient metals such as Fe, Ni, Cu, and Zn from mineral phases. These complexes are taken up by organisms via specific membrane receptors, thereby differentially impacting the bioavailability of these metals to the plant and microbial community. Although the importance of these chelation strategies for individual organisms has been well established, little is known about which pathways coexist within rhizosphere microbiomes or howmore » they interact and compete for metal binding. Identifying these metallophores within natural ecosystems has remained a formidable analytical challenge due to the vast diversity of compounds and poorly defined metabolic processes in complex soil matrices. Herein, we employed recently developed liquid chromatography (LC) mass spectrometry (MS) methods to characterize the speciation of water-soluble dissolved trace elements (Fe, Ni, Cu, and Zn) of soils from native tallgrass prairies in Kansas and Iowa. Both plant and fungal metallophores were identified, revealing compound-specific patterns of chelation to biologically essential metals. Numerous metabolites typically implicated in plant Fe acquisition and homeostasis, including mugineic acids, deoxymugineic acid, nicotianamine, and hydroxynicotianamines, dominated the speciation of divalent metals such as Ni, Cu, and Zn (2–90 pmol/g soil). In contrast, the fungal siderophore ferricrocin was specific for trivalent Fe (7–32 pmol/g soil). These results define biochemical pathways that underpin the regulation of metals in the grassland rhizosphere. They also raise new questions about the competition of these compounds for metal binding and their bioavailability to different members of the rhizosphere population. In

Metal regeneration of iron chelates in nitric oxide scrubbing

DOEpatents

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.

Metal regeneration of iron chelates in nitric oxide scrubbing

DOEpatents

Chang, Shih-Ger; Littlejohn, David; Shi, Yao

1997-08-19

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

Effect of Sterilization Methods on Electrospun Poly(lactic acid) (PLA) Fiber Alignment for Biomedical Applications.

PubMed

Valente, T A M; Silva, D M; Gomes, P S; Fernandes, M H; Santos, J D; Sencadas, V

2016-02-10

Medically approved sterility methods should be a major concern when developing a polymeric scaffold, mainly when commercialization is envisaged. In the present work, poly(lactic acid) (PLA) fiber membranes were processed by electrospinning with random and aligned fiber alignment and sterilized under UV, ethylene oxide (EO), and γ-radiation, the most common ones for clinical applications. It was observed that UV light and γ-radiation do not influence fiber morphology or alignment, while electrospun samples treated with EO lead to fiber orientation loss and morphology changing from cylindrical fibers to ribbon-like structures, accompanied to an increase of polymer crystallinity up to 28%. UV light and γ-radiation sterilization methods showed to be less harmful to polymer morphology, without significant changes in polymer thermal and mechanical properties, but a slight increase of polymer wettability was detected, especially for the samples treated with UV radiation. In vitro results indicate that both UV and γ-radiation treatments of PLA membranes allow the adhesion and proliferation of MG 63 osteoblastic cells in a close interaction with the fiber meshes and with a growth pattern highly sensitive to the underlying random or aligned fiber orientation. These results are suggestive of the potential of both γ-radiation sterilized PLA membranes for clinical applications in regenerative medicine, especially those where customized membrane morphology and fiber alignment is an important issue.

Neuroprotection by a novel brain permeable iron chelator, VK-28, against 6-hydroxydopamine lession in rats.

PubMed

Shachar, Dorit Ben; Kahana, Nava; Kampel, Vladimir; Warshawsky, Abraham; Youdim, Moussa B H

2004-02-01

Significant increase in iron occurs in the substantia nigra pars compacta of Parkinsonian subjects, and in 6-hydroxydopamine (6-OHDA) treated rats and monkeys. This increase in iron has been attributed to its release from ferritin and is associated with the generation of reactive oxygen species and the onset of oxidative stress-induced neurodegeneration. Several iron chelators with hydroxyquinoline backbone were synthesized and their ability to inhibit basal as well as iron-induced mitochondrial lipid peroxidation was examined. The neuroprotective potential of the brain permeable iron chelator, VK-28 (5-[4-(2-hydroxyethyl) piperazine-1-ylmethyl]-quinoline-8-ol), injected either intraventricularly (ICV) or intraperitoneally (IP), to 6-OHDA lesioned rats was investigated. VK-28 inhibited both basal and Fe/ascorbate induced mitochondrial membrane lipid peroxidation, with an IC(50) (12.7 microM) value comparable to that of the prototype iron chelator, desferal, which does not cross the blood brain barrier. At an ICV pretreatment dose as low as 1 microg, VK-28 was able to completely protect against ICV 6-OHDA (250 microg) induced striatal dopaminergic lesion, as measured by dopamine (DA), dihydroxyphenylacetic acid (DOPAC) and homovanilic acid (HVA) levels. IP injection of rats with VK-28 (1 and 5 mg/kg) daily for 10 and 7 days, respectively, demonstrated significant neuroprotection against ICV 6-OHDA at the higher dose, with 68% protection against loss of dopamine at 5mg/kg dosage of VK-28. The present study is the first to show neuroprotection with a brain permeable iron chelator. The latter can have implications for the treatment of Parkinson's disease and other neurodegenerative diseases (Alzheimer's disease, Friedreich ataxia, aceruloplasminemia, Hallervorden Spatz syndrome) where abnormal iron accumulation in the brain is thought to be associated with the degenerative processes.

Why the NIH Trial to Assess Chelation Therapy (TACT) Should Be Abandoned

PubMed Central

Atwood, Kimball C.; Woeckner, Elizabeth; Baratz, Robert S.; Sampson, Wallace I.

2008-01-01

The National Institutes of Health (NIH) Trial to Assess Chelation Therapy (TACT) was begun in 2003 and is expected to be completed in 2009. It is a trial of office-based, intravenous disodium ethylene-diamine-tetra-acetic acid (Na2EDTA) as a treatment for coronary artery disease (CAD). A few case series in the 1950s and early 1960s had found Na2EDTA to be ineffective for CAD or peripheral vascular disease (PVD). Nevertheless, a few hundred physicians, almost all of whom advocate other dubious treatments, continued to peddle chelation as an office treatment. They claim that chelation dramatically improves symptoms and prolongs life in 80% to 90% of patients. In response, academics performed 4 controlled trials during the 1990s. None favored chelation, but chelationists repudiated those findings. We have investigated the method and the trial. We present our findings in 4 parts: history, origin and nature of the TACT, state of the evidence, and risks. We present evidence that chelationists and their organization, the American College for Advancement in Medicine, used political connections to pressure the NIH to fund the TACT. The TACT protocols justified the trial by misrepresenting case series and by ignoring evidence of risks. The trial employs nearly 100 unfit co-investigators. It conflates disodium EDTA and another, somewhat safer drug. It lacks precautions necessary to minimize risks. The consent form reflects those shortcomings and fails to disclose apparent proprietary interests. The trial's outcome will be unreliable and almost certainly equivocal, thus defeating its stated purpose. We conclude that the TACT is unethical, dangerous, pointless, and wasteful. It should be abandoned. PMID:18596934

Mitochondrial fatty acid biosynthesis and muscle fiber plasticity in very long-chain acyl-CoA dehydrogenase-deficient mice.

PubMed

Tucci, Sara; Mingirulli, Nadja; Wehbe, Zeinab; Dumit, Verónica I; Kirschner, Janbernd; Spiekerkoetter, Ute

2018-01-01

The white skeletal muscle of very long-chain acyl-CoA-dehydrogenase-deficient (VLCAD -/- ) mice undergoes metabolic modification to compensate for defective β-oxidation in a progressive and time-dependent manner by upregulating glucose oxidation. This metabolic regulation seems to be accompanied by morphologic adaptation of muscle fibers toward the glycolytic fiber type II with the concomitant upregulation of mitochondrial fatty acid biosynthesis (mFASII) and lipoic acid biosynthesis. Dietary supplementation of VLCAD -/- mice with different medium-chain triglycerides over 1 year revealed that odd-chain species has no effect on muscle fiber switch, whereas even-chain species inhibit progressive metabolic adaptation. Our study shows that muscle may undergo adaptive mechanisms that are modulated by dietary supplementation. We describe for the first time a concomitant change of mFASII in this muscular adaptation process. © 2017 Federation of European Biochemical Societies.

Injection port derivatization following ion-pair hollow fiber-protected liquid-phase microextraction for determining acidic herbicides by gas chromatography/mass spectrometry.

PubMed

Wu, Jingming; Lee, Hian Kee

2006-10-15

Injection port derivatization following ion-pair hollow fiber-protected liquid-phase microextraction (LPME) for the trace determination of acidic herbicides (2,4-dichlorobenzoic acid, 2,4-dichlorophenoxyacetic acid, 2-(2,4-dichlorophenoxy)propionic acid, 3,5-dichlorobenzoic acid, 2-(2,4,5-trichlorophenoxy)propionic acid) in aqueous samples by gas chromatography/mass spectrometry (GC/MS) was developed. Prior to GC injection port derivatization, acidic herbicides were converted into their ion-pair complexes with tetrabutylammonium chloride in aqueous samples and then extracted by 1-octanol impregnated in the hollow fiber. Upon injection, ion pairs of acidic herbicides were quantitatively derivatized to their butyl esters in the GC injection port. Thus, several parameters related to the derivatization process (i.e., injection temperature, purge-off time) were evaluated, and main parameters affecting the hollow fiber-protected LPME procedure such as extraction organic solvent, ion-pair reagent type, pH of aqueous medium, concentration of ion-pair reagent, sodium chloride concentration added to the aqueous medium, stirring speed, and extraction time profile, optimized. At the selected extraction and derivatization conditions, no matrix effects were observed. This method proved good repeatability (RSDs <12.3%, n = 6) and good linearity (r2 > or = 0.9939) for spiked deionized water samples for five analytes. The limits of detection were in the range of 0.51-13.7 ng x L(-1) (S/N =3) under GC/MS selected ion monitoring mode. The results demonstrated that injection port derivatization following ion-pair hollow fiber-protected LPME was a simple, rapid, and accurate method for the determination of trace acidic herbicides from aqueous samples. In addition, this method proved to be environmentally friendly since it completely avoided open derivatization with potentially hazardous reagents.

Cell proliferation on PVA/sodium alginate and PVA/poly(γ-glutamic acid) electrospun fiber.

PubMed

Yang, Jen Ming; Yang, Jhe Hao; Tsou, Shu Chun; Ding, Chian Hua; Hsu, Chih Chin; Yang, Kai Chiang; Yang, Chun Chen; Chen, Ko Shao; Chen, Szi Wen; Wang, Jong Shyan

2016-09-01

To overcome the obstacles of easy dissolution of PVA nanofibers without crosslinking treatment and the poor electrospinnability of the PVA cross-linked nanofibers via electrospinning process, the PVA based electrospun hydrogel nanofibers are prepared with post-crosslinking method. To expect the electrospun hydrogel fibers might be a promising scaffold for cell culture and tissue engineering applications, the evaluation of cell proliferation on the post-crosslinking electrospun fibers is conducted in this study. At beginning, poly(vinyl alcohol) (PVA), PVA/sodium alginate (PVASA) and PVA/poly(γ-glutamic acid) (PVAPGA) electrospun fibers were prepared by electrospinning method. The electrospun PVA, PVASA and PVAPGA nanofibers were treated with post-cross-linking method with glutaraldehyde (Glu) as crosslinking agent. These electrospun fibers were characterized with thermogravimetry analysis (TGA) and their morphologies were observed with a scanning electron microscope (SEM). To support the evaluation and explanation of cell growth on the fiber, the study of 3T3 mouse fibroblast cell growth on the surface of pure PVA, SA, and PGA thin films is conducted. The proliferation of 3T3 on the electrospun fiber surface of PVA, PVASA, and PVAPGA was evaluated by seeding 3T3 fibroblast cells on these crosslinked electrospun fibers. The cell viability on electrospun fibers was conducted with water-soluble tetrazolium salt-1 assay (Cell Proliferation Reagent WST-1). The morphology of the cells on the fibers was also observed with SEM. The results of WST-1 assay revealed that 3T3 cells cultured on different electrospun fibers had similar viability, and the cell viability increased with time for all electrospun fibers. From the morphology of the cells on electrospun fibers, it is found that 3T3 cells attached on all electrospun fiber after 1day seeded. Cell-cell communication was noticed on day 3 for all electrospun fibers. Extracellular matrix (ECM) productions were found and

The Ca(2+)-EDTA chelation as standard reaction to validate Isothermal Titration Calorimeter measurements (ITC).

PubMed

Ràfols, Clara; Bosch, Elisabeth; Barbas, Rafael; Prohens, Rafel

2016-07-01

A study about the suitability of the chelation reaction of Ca(2+)with ethylenediaminetetraacetic acid (EDTA) as a validation standard for Isothermal Titration Calorimeter measurements has been performed exploring the common experimental variables (buffer, pH, ionic strength and temperature). Results obtained in a variety of experimental conditions have been amended according to the side reactions involved in the main process and to the experimental ionic strength and, finally, validated by contrast with the potentiometric reference values. It is demonstrated that the chelation reaction performed in acetate buffer 0.1M and 25°C shows accurate and precise results and it is robust enough to be adopted as a standard calibration process. Copyright © 2016 Elsevier B.V. All rights reserved.

Enhancement of the Mechanical Properties of a Polylactic Acid/Flax Fiber Biocomposite by WPU, WPU/Starch, and TPS Polyurethanes Using Coupling Additives

NASA Astrophysics Data System (ADS)

Miskolczi, N.; Sedlarik, V.; Kucharczyk, P.; Riegel, E.

2018-01-01

This work is addressed to the synthesis of bio-based polymers and investigation of their application in a flax-fiber-reinforced polylactic acid. Polyurethane polymers were synthesized from polyphenyl-methane-diisocyanate, poly (ethylene oxide) glycol, and ricinoleic acid, and their structure was examined by the Fourier transform infrared spectroscopy, thermogravimetric analysis, and differential scanning calorimetry. It was established that the introduction of flax fibers and different compatibilizers into the polymers improved their mechanical properties. A vinyl-trimetoxy-silane and polyalkenyl-polymaleic-anhydride derivative with a high acid number produced the best effect on the properties, but samples without additives had the highest water absorption capacity. SEM micrographs showed a good correlation between the morphology of fracture structure of the composites and the mechanical properties of flax fibers.

Hollow fiber gas-liquid membrane contactors for acid gas capture: a review.

PubMed

Mansourizadeh, A; Ismail, A F

2009-11-15

Membrane contactors using microporous membranes for acid gas removal have been extensively reviewed and discussed. The microporous membrane acts as a fixed interface between the gas and the liquid phase without dispersing one phase into another that offers a flexible modular and energy efficient device. The gas absorption process can offer a high selectivity and a high driving force for transport even at low concentrations. Using hollow fiber gas-liquid membrane contactors is a promising alternative to conventional gas absorption systems for acid gas capture from gas streams. Important aspects of membrane contactor as an efficient energy devise for acid gas removal including liquid absorbents, membrane characteristics, combination of membrane and absorbent, mass transfer, membrane modules, model development, advantages and disadvantages were critically discussed. In addition, current status and future potential in research and development of gas-liquid membrane contactors for acid gas removal were also briefly discussed.

Novel hexadentate and pentadentate chelators for 64Cu-based targeted PET imaging

PubMed Central

Sin, Inseok; Kang, Chisoo; Bandara, Nilantha; Sun, Xiang; Zhong, Yongliang; Rogers, Buck E.; Chong, Hyun-Soon

2014-01-01

A series of new hexadentate and pentadentate chelators were designed and synthesized as chelators of 64Cu. The new pentadentate and hexadentate chelators contain different types of donor groups and are expected to form neutral complexes with Cu(II). The new chelators were evaluated for complex kinetics and stability with 64Cu. The new chelators instantly bound to 64Cu with high labeling efficiency and maximum specific activity. All 64Cu-radiolabeled complexes in human serum remained intact for 2 days. The 64Cu-radiolabeled complexes were further challenged by EDTA in a 100-fold molar excess. Among the 64Cu-radiolabeled complexes evaluated, 64Cu-complex of the new chelator E was well tolerated with a minimal transfer of 64Cu to EDTA. 64Cu-radiolabeled complex of the new chelator E was further evaluated for biodistribution studies using mice and displayed rapid blood clearance and low organ uptake. 64Cu-chelator E produced a favorable in vitro and in vivo complex stability profiles comparable to 64Cu complex of the known hexadentate NOTA chelator. The in vitro and in vivo data highlight strong potential of the new chelator E for targeted PET imaging application. PMID:24657050

Chelating ligands for nanocrystals' surface functionalization.

PubMed

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

2004-09-22

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

Glyphosate, a chelating agent-relevant for ecological risk assessment?

PubMed

Mertens, Martha; Höss, Sebastian; Neumann, Günter; Afzal, Joshua; Reichenbecher, Wolfram

2018-02-01

Glyphosate-based herbicides (GBHs), consisting of glyphosate and formulants, are the most frequently applied herbicides worldwide. The declared active ingredient glyphosate does not only inhibit the EPSPS but is also a chelating agent that binds macro- and micronutrients, essential for many plant processes and pathogen resistance. GBH treatment may thus impede uptake and availability of macro- and micronutrients in plants. The present study investigated whether this characteristic of glyphosate could contribute to adverse effects of GBH application in the environment and to human health. According to the results, it has not been fully elucidated whether the chelating activity of glyphosate contributes to the toxic effects on plants and potentially on plant-microorganism interactions, e.g., nitrogen fixation of leguminous plants. It is also still open whether the chelating property of glyphosate is involved in the toxic effects on organisms other than plants, described in many papers. By changing the availability of essential as well as toxic metals that are bound to soil particles, the herbicide might also impact soil life, although the occurrence of natural chelators with considerably higher chelating potentials makes an additional impact of glyphosate for most metals less likely. Further research should elucidate the role of glyphosate (and GBH) as a chelator, in particular, as this is a non-specific property potentially affecting many organisms and processes. In the process of reevaluation of glyphosate its chelating activity has hardly been discussed.

Iron Reverses Impermeable Chelator Inhibition of DNA Synthesis in CCl39 Cells

NASA Astrophysics Data System (ADS)

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

1994-08-01

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

Heavy Metal Displacement in Chelate-Assisted Phytoremediation of Biosolids Soil

NASA Astrophysics Data System (ADS)

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

2005-05-01

Heavy metals in biosolids (sewage sludge) applied to land contaminate the soil. 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 biosolids following solubilization with chelates. The objective of this work was to determine the mobility of heavy metals, as affected by a chelate, in soil (Haynie very fine sandy loam) from a 25-year old sludge farm. Soil columns (105 cm long; 39 cm in diameter) either had a plant (hybrid poplar; Populus deltoides Marsh. x P. nigra L.) or no plant. When the poplars were 144 days old, the tetrasodium salt of the chelating agent EDTA (ethylenediamine-tetraacetic acid) was irrigated onto the soil at a rate of 1 g per kg of soil. Drainage water, soil, and plants were analyzed for three toxic heavy metals (Cd, Ni, Pb) and four essential heavy metals (Cu, Fe, Mn, Zn). Without EDTA, concentrations of the seven heavy metals in the leachate from columns with or without plants were low or below detection limits. With or without plants, the EDTA mobilized all heavy metals and increased their concentration in drainage water. Without plants, the concentrations of Cd, Cu, Fe, Pb, and Zn in the leachate from columns with EDTA were above drinking-water standards. (There is no drinking-water standard for Ni.) The presence of poplar plants in the soil reduced the concentrations of Cu, Fe, and Zn in the leachate so it fell within drinking-water standards. Concentrations of Cd and Pb in the leachate remained above drinking-water standards with or without plants. At harvest (124 days after the EDTA application), total concentration of each heavy metal in the soil at different depths in the columns with EDTA was similar to that in the columns without EDTA. The chelate did not affect the concentration of heavy metals in the roots, stems, or leaves

EDTA chelation therapy alone and in combination with oral high-dose multivitamins and minerals for coronary disease: The factorial group results of the Trial to Assess Chelation Therapy.

PubMed

Lamas, Gervasio A; Boineau, Robin; Goertz, Christine; Mark, Daniel B; Rosenberg, Yves; Stylianou, Mario; Rozema, Theodore; Nahin, Richard L; Terry Chappell, L; Lindblad, Lauren; Lewis, Eldrin F; Drisko, Jeanne; Lee, Kerry L

2014-07-01

Disodium ethylenediaminetetraacetic acid (EDTA) reduced adverse cardiac outcomes in a factorial trial also testing oral vitamins. This report describes the intent-to-treat comparison of the 4 factorial groups overall and in patients with diabetes. This was a double-blind, placebo-controlled, 2 × 2 factorial multicenter randomized trial of 1,708 post-myocardial infarction (MI) patients ≥50 years of age and with creatinine ≤2.0 mg/dL randomized to receive 40 EDTA chelation or placebo infusions plus 6 caplets daily of a 28-component multivitamin-multimineral mixture or placebo. The primary end point was a composite of total mortality, MI, stroke, coronary revascularization, or hospitalization for angina. Median age was 65 years, 18% were female, 94% were Caucasian, 37% were diabetic, 83% had prior coronary revascularization, and 73% were on statins. Five-year Kaplan-Meier estimates for the primary end point was 31.9% in the chelation + high-dose vitamin group, 33.7% in the chelation + placebo vitamin group, 36.6% in the placebo infusion + active vitamin group, and 40.2% in the placebo infusions + placebo vitamin group. The reduction in primary end point by double active treatment compared with double placebo was significant (hazard ratio 0.74, 95% CI 0.57-0.95, P = .016). In patients with diabetes, the primary end point reduction of double active compared with double placebo was more pronounced (hazard ratio 0.49, 95% CI 0.33-0.75, P < .001). In stable post-MI patients on evidence-based medical therapy, the combination of oral high-dose vitamins and chelation therapy compared with double placebo reduced clinically important cardiovascular events to an extent that was both statistically significant and of potential clinical relevance. Copyright © 2014 The Authors. Published by Mosby, Inc. All rights reserved.

Catalase purification from rat liver with iron-chelated poly(hydroxyethyl methacrylate-N-methacryloyl-(l)-glutamic acid) cryogel discs.

PubMed

Göktürk, Ilgım; Perçin, Işık; Denizli, Adil

2016-08-17

In this study, iron-chelated poly(hydroxyethyl methacrylate-N-methacryloyl-(l)-glutamic acid) (PHEMAGA/Fe(3+)) cryogel discs were prepared. The PHEMAGA/Fe(3+) cryogel discs were characterized by elemental analysis, scanning electron microscopy, Fourier transform infrared spectroscopy, swelling tests, and surface area measurements. The PHEMAGA/Fe(3+) cryogel discs had large pores ranging from 10 to 100 µm with a swelling degree of 9.36 g H2O/g cryogel. Effects of pH, temperature, initial catalase concentration, and flow rate on adsorption capacity of the PHEMAGA/Fe(3+) cryogel discs were investigated. Maximum catalase adsorption capacity (62.6 mg/g) was obtained at pH 7.0, 25°C, and 3 mg/ml initial catalase concentration. The PHEMAGA/Fe(3+) cryogel discs were also tested for the purification of catalase from rat liver. After tissue homogenization, purification of catalase was performed using the PHEMAGA/Fe(3+) cryogel discs and catalase was obtained with a yield of 54.34 and 16.67 purification fold.

Water Uptake Behavior and Young Modulus Prediction of Composites Based on Treated Sisal Fibers and Poly(Lactic Acid)

PubMed Central

Orue, Ander; Eceiza, Arantxa; Peña-Rodriguez, Cristina; Arbelaiz, Aitor

2016-01-01

The main aim of this work was to study the effect of sisal fiber surface treatments on water uptake behavior of composites based on untreated and treated fibers. For this purpose, sisal fibers were treated with different chemical treatments. All surface treatments delayed the water absorption of fibers only for a short time of period. No significant differences were observed in water uptake profiles of composites based on fibers with different surface treatments. After water uptake period, tensile strength and Young modulus values of sisal fiber/poly(lactic acid) (PLA) composites were decreased. On the other hand, composites based on NaOH + silane treated fibers showed the lowest diffusion coefficient values, suggesting that this treatment seemed to be the most effective treatment to reduce water diffusion rate into the composites. Finally, Young modulus values of composites, before water uptake period, were predicted using different micromechanical models and were compared with experimental data. PMID:28773524

Strategies for the preparation of bifunctional gadolinium(III) chelators

PubMed Central

Frullano, Luca; Caravan, Peter

2012-01-01

The development of gadolinium chelators that can be easily and readily linked to various substrates is of primary importance for the development high relaxation efficiency and/or targeted magnetic resonance imaging (MRI) contrast agents. Over the last 25 years a large number of bifunctional chelators have been prepared. For the most part, these compounds are based on ligands that are already used in clinically approved contrast agents. More recently, new bifunctional chelators have been reported based on complexes that show a more potent relaxation effect, faster complexation kinetics and in some cases simpler synthetic procedures. This review provides an overview of the synthetic strategies used for the preparation of bifunctional chelators for MRI applications. PMID:22375102

Isoxazole moiety in the linker region of HDAC inhibitors adjacent to the Zn-chelating group: effects on HDAC biology and antiproliferative activity.

PubMed

Tapadar, Subhasish; He, Rong; Luchini, Doris N; Billadeau, Daniel D; Kozikowski, Alan P

2009-06-01

A series of hydroxamic acid based histone deacetylase inhibitors 6-15, containing an isoxazole moiety adjacent to the Zn-chelating hydroxamic acid, is reported herein. Some of these compounds showed nanomolar activity in the HDAC isoform inhibitory assay and exhibited micro molar inhibitory activity against five pancreatic cancer cell lines.

Forensic analysis of anthraquinone, azo, and metal complex acid dyes from nylon fibers by micro-extraction and capillary electrophoresis.

PubMed

Stefan, Amy R; Dockery, Christopher R; Nieuwland, Alexander A; Roberson, Samantha N; Baguley, Brittany M; Hendrix, James E; Morgan, Stephen L

2009-08-01

The extraction and separation of dyes present on textile fibers offers the possibility of enhanced discrimination between forensic trace fiber evidence. An automated liquid sample handling workstation was programmed to deliver varying solvent combinations to acid-dyed nylon samples, and the resulting extracts were analyzed by an ultraviolet/visible microplate reader to evaluate extraction efficiencies at different experimental conditions. Combinatorial experiments using three-component mixture designs varied three solvents (water, pyridine, and aqueous ammonia) and were employed at different extraction temperatures for various extraction durations. The extraction efficiency as a function of the three solvents (pyridine/ammonia/water) was modeled and used to define optimum conditions for the extraction of three subclasses of acid dyes (anthraquinone, azo, and metal complex) from nylon fibers. The capillary electrophoresis analysis of acid dye extracts is demonstrated using an electrolyte solution of 15 mM ammonium acetate in acetonitrile/water (40:60, v/v) at pH 9.3. Excellent separations and discriminating diode array spectra are obtained even for dyes of similar color.

Development of metal-chelating inhibitors for the Class II fructose 1,6-bisphosphate (FBP) aldolase.

PubMed

Labbé, Geneviève; Krismanich, Anthony P; de Groot, Sarah; Rasmusson, Timothy; Shang, Muhong; Brown, Matthew D R; Dmitrienko, Gary I; Guillemette, J Guy

2012-07-01

It has long been suggested that the essential and ubiquitous enzyme fructose 1,6-bisphosphate (FBP) aldolase could be a good drug target against bacteria and fungi, since lower organisms possess a metal-dependant (Class II) FBP aldolase, as opposed to higher organisms which possess a Schiff-base forming (Class I) FBP aldolase. We have tested the capacity of derivatives of the metal-chelating compound dipicolinic acid (DPA), as well a thiol-containing compound, to inhibit purified recombinant Class II FBP aldolases from Mycobacterium tuberculosis, Pseudomonas aeruginosa, Bacillus cereus, Bacillus anthracis, and from the Rice Blast causative agent Magnaporthe grisea. The aldolase from M. tuberculosis was the most sensitive to the metal-chelating inhibitors, with an IC(50) of 5.2 μM with 2,3-dimercaptopropanesulfonate (DMPS) and 28 μM with DPA. DMPS and the synthesized inhibitor 6-(phosphonomethyl)picolinic acid inhibited the enzyme in a time-dependent, competitive fashion, with second order rate constants of 273 and 270 M(-1) s(-1) respectively for the binding of these compounds to the M. tuberculosis aldolase's active site in the presence of the substrate FBP (K(M) 27.9 μM). The most potent first generation inhibitors were modeled into the active site of the M. tuberculosis aldolase structure, with results indicating that the metal chelators tested cannot bind the catalytic zinc in a bidentate fashion while it remains in its catalytic location, and that most enzyme-ligand interactions involve the phosphate binding pocket residues. Copyright © 2012 Elsevier Inc. All rights reserved.

Bioinspired Polyelectrolyte-Assembled Graphene-Oxide-Coated C18 Composite Solid-Phase Microextraction Fibers for In Vivo Monitoring of Acidic Pharmaceuticals in Fish.

PubMed

Qiu, Junlang; Chen, Guosheng; Liu, Shuqin; Zhang, Tianlang; Wu, Jiayi; Wang, Fuxin; Xu, Jianqiao; Liu, Yan; Zhu, Fang; Ouyang, Gangfeng

2016-06-07

A novel solid-phase microextraction (SPME) fiber was prepared by gluing poly(diallyldimethylammonium chloride) (PDDA) assembled graphene oxide (GO)-coated C18 composite particles (C18@GO@PDDA) onto a quartz fiber with polyaniline (PANI). The fiber surface coating was sequentially modified with bioinspired polynorepinephrine, which provided a smooth biointerface and makes the coating suitable for in vivo sampling. The novel custom-made coating was used to extract acidic pharmaceuticals, and high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) was employed for analysis. The custom-made coating exhibited a much higher extraction efficiency than the previously used commercial polydimethylsiloxane (PDMS) and polyacrylate (PA) coatings. The custom-made coating also possessed satisfactory stability (the relative standard deviations (RSDs) ranged from 1.60% to 10.3% for six sampling-desorption cycles), interfiber reproducibility (the RSDs ranged from 2.61% to 11.5%), and resistance to matrix effects. The custom-made fibers were used to monitor the presence of acid pharmaceuticals in dorsal-epaxial muscle of living fish, and satisfactory sensitivities (limits of detection ranged from 0.13 ng/g to 7.56 ng/g) were achieved. The accuracies were verified by the comparison with liquid extraction. Moreover, the novel fibers were successfully used to monitor the presence of acidic pharmaceuticals in living fish, which demonstrated that the custom-made fibers were feasible for possible long-term in vivo continuous pharmaceutical monitoring.

Metal chelate process to remove pollutants from fluids

DOEpatents

Chang, Shih-Ger T.

1994-01-01

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

Metal chelate process to remove pollutants from fluids

DOEpatents

Chang, S.G.T.

1994-12-06

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

Inhibition of Pseudomonas aeruginosa biofilm formation by 2,2’-bipyridyl, lipoic, kojic and picolinic acids

PubMed Central

Çevik, Kübra; Ulusoy, Seyhan

2015-01-01

Objective(s): The inhibitory effects of iron chelators, and FeCl3 chelation on biofilm formation and swarming motility were investigated against an opportunistic human pathogen Pseudomonas aeruginosa. Materials and Methods: The inhibitory activity of 2,2’-bipyridyl, lipoic acid, kojic acid and picolinic acid on biofilm formation of P. aeruginosa strain PAO1 and three clinical isolates (P. aeruginosa PAK01, P. aeruginosa PAK02 and P. aeruginosa PAK03) were investigated, based on crystal violet assay, and swarming motility test. Results: The kojic, lipoic and picolinic acid inhibited biofilm formation by 5-33% in all tested P. aeruginosa isolates. When chelated iron was added, biofilm inhibition rates were determined to be 39-57%. Among the tested chelators against P. aeruginosa, lipoic acid (84%) and kojic acid (68%) presented the highest inhibition of swarming motility. This is the first study to report the inhibitory effect of lipoic acid on biofilm formation and swarming motility of P. aeruginosa. Conclusion: It is considered that lipoic and picolinic acids can serve as alternatives for the treatment of the P. aeruginosa infections by inhibiting biofilm formation. PMID:26557964

Mechanisms for chelator stimulation of microbial Fe(III) -oxide reduction

USGS Publications Warehouse

Lovley, D.R.; Woodward, J.C.

1996-01-01

The mechanisms by which nitrilotriacetic acid (NTA) stimulated Fe(III) reduction in sediments from a petroleum-contaminated aquifer were investigated in order to gain insight into how added Fe(III) chelators stimulate the activity of hydrocarbon-degrading, Fe(III)-reducing microorganisms in these sediments, and how naturally occurring Fe(III) chelators might promote Fe(III) reduction in aquatic sediments. NTA solubilized Fe(III) from the aquifer sediments. NTA stimulation of microbial Fe(III) reduction did not appear to be the result of making calcium, magnesium, potassium, or trace metals more available to the microorganisms. Stimulation of Fe(III) reduction could not be attributed to NTA serving as a source of carbon or fixed nitrogen for Fe(III)-reducing bacteria as NTA was not degraded in the sediments. Studies with the Fe(III)-reducing microorganism, Geobacter metallireducens, and pure Fe(III)-oxide forms, demonstrated that NTA stimulated the reduction of a variety of Fe(III) forms, including highly crystalline Fe(III)-oxides such as goethite and hematite. The results suggest that NTA solubilization of insoluble Fe(III)-oxide is an important mechanism for the stimulation of Fe(III) reduction by NTA in aquifer sediments.

Monitoring the effects of chelating agents and electrical fields on active forms of Pb and Zn in contaminated soil.

PubMed

Tahmasbian, Iman; Safari Sinegani, Ali Akbar

2013-11-01

The application of electrical fields and chelating agents is an innovative hybrid technology used for the decontamination of soil polluted by heavy metals. The effects of four center-oriented electrical fields and chelating agents on active fractions of lead and zinc were investigated in this pot experiment. Ethylenediaminetetraacetic acid (EDTA) as a synthetic chelator and cow manure extract (CME) and poultry manure extract (PME) as natural chelators were applied to the pots (2 g kg(-1)) 30 days after the first irrigation. Two weeks later, four center-oriented electrical fields were applied in each pot (in three levels of 0, 10, and 30 V) for 1 h each day for 14 days. The soil near the cathode and anodes was collected and analyzed as cathodic and anodic soil, respectively. Results indicated that the soluble-exchangeable fraction of lead and zinc were decreased in the cathodic soil, while the carbonate-bound fractions were increased. In the anodic soil, however, the opposite result was observed. EDTA enhanced the soluble-exchangeable form of the metals in both anodic and cathodic soils. Furthermore, the amounts of carbonate-bound heavy metals were increased by the application of CME in both soils. The organic-bound fraction of the metals was increased by the application of natural chelators, while electrical fields had no significant impacts on this fraction.

Effects of chelating agent and acids on Biodentine.

PubMed

Ballal, V; Marques, J N; Campos, C N; Lima, C O; Simão, R A; Prado, M

2018-06-01

To evaluate the effect of distilled water, ethylenediaminetetraacetic acid (EDTA), phosphoric acid and maleic acid on Biodentine regarding surface topography, microhardness and push-out bond strength (POBS). Fifty-two cylindrical shaped Biodentine specimens were divided into groups: control (distilled water); EDTA (17% EDTA); PA (37% phosphoric acid); and MA (7% maleic acid). Surfaces were evaluated by topographic analysis and Vickers microhardness test. Topographic changes were evaluated qualitatively and microhardness was statistically analyzed by Kruskal-Wallis test. Forty mandibular molars were used to simulate clinical conditions. The crowns were removed and a perforation was created at the furcal floor. The Biodentine was packed into the root perforations and the roots were divided into four groups (DW, EDTA, PA, MA). Samples were stored and subjected to interfacial analysis. POBS data were analyzed by Kruskal-Wallis and Dunn tests. Ethylenediaminetetraacetic acid, MA and PA changed the morphology of the Biodentine surface. PA showed microhardness similar to distilled water (P > 0.05), while MA and EDTA demonstrated reduced values when compared with PA (P < 0.05). PA improved the POBS of Biodentine in comparison with the control. Changes in the topography, microhardness and POBS of Biodentine are associated with irrigant agent used. © 2018 Australian Dental Association.

Biodegradable gadolinium-chelated cationic poly(urethane amide) copolymers for gene transfection and magnetic resonance imaging.

PubMed

Gao, Xiaolong; Wang, Gangmin; Shi, Ting; Shao, Zhihong; Zhao, Peng; Shi, Donglu; Ren, Jie; Lin, Chao; Wang, Peijun

2016-08-01

Theranostic nano-polyplexes containing gene and imaging agents hold a great promise for tumor diagnosis and therapy. In this work, we develop a group of new gadolinium (Gd)-chelated cationic poly(urethane amide)s for gene delivery and T1-weighted magnetic resonance (MR) imaging. Cationic poly(urethane amide)s (denoted as CPUAs) having multiple disulfide bonds, urethane and amide linkages were synthesized by stepwise polycondensation reaction between 1,4-bis(3-aminopropyl)piperazine and a mixture of di(4-nitrophenyl)-2, 2'-dithiodiethanocarbonate (DTDE-PNC) and diethylenetriaminepentaacetic acid (DTPA) dianhydride at varied molar ratios. Then, Gd-chelated CPUAs (denoted as GdCPUAs) were produced by chelating Gd(III) ions with DTPA residues of CPUAs. These GdCPUAs could condense gene into nanosized and positively-charged polyplexes in a physiological condition and, however, liberated gene in an intracellular reductive environment. In vitro transfection experiments revealed that the GdCPUA at a DTDE-PNC/DTPA residue molar ratio of 85/15 induced the highest transfection efficiency in different cancer cells. This efficiency was higher than that yielded with 25kDa branched polyethylenimine as a positive control. GdCPUAs and their polyplexes exhibited low cytotoxicity when an optimal transfection activity was detected. Moreover, GdCPUAs may serve as contrast agents for T1-weighted magnetic resonance imaging. The results of this work indicate that biodegradable Gd-chelated cationic poly(urethane amide) copolymers have high potential for tumor theranostics. Copyright © 2016 Elsevier B.V. All rights reserved.

Sorption and complexation of Eu(III) on alumina: effects of pH, ionic strength, humic acid and chelating resin on kinetic dissociation study.

PubMed

Wang, X; Xu, D; Chen, L; Tan, X; Zhou, X; Ren, A; Chen, Ch

2006-04-01

The effects of pH (pH=2-12), ionic strength (0.01-2 mol/l NaNO(3)) and humic acid on the sorption and complexation of Eu(III) on alumina were investigated by using batch techniques. The experiments were carried out at room temperature and under ambient conditions. The results indicate that the sorption of Eu(III) on alumina is strongly influenced by humic acid. The sorption of Eu(III) on alumina is significantly dependent on pH values and independent of ionic strength. The sorption of Eu(III) on alumina may be attributed to surface complexation. The species of Eu(III) on HA-alumina colloids is dominated by both HA and alumina, and the addition sequences of HA or Eu(III) to the ternary system do not influence the sorption of Eu(III) to HA-coated alumina. Kinetic dissociation of Eu(III) from bare and HA-coated alumina was also studied by using the chelating resin. The result was discussed by a pseudo-first-order kinetics model.

Adsorption mechanism of 2,4-dichlorophenoxyacetic acid onto nitric-acid-modified activated carbon fiber.

PubMed

Li, Qun; Sun, Jie; Ren, Tianhao; Guo, Lin; Yang, Zhilin; Yang, Qi; Chen, Hai

2018-04-01

Adsorption by carbon materials is one of the relatively fast methods in present research, which is widely used in emergency events. Activated carbon fiber (ACF) modified by nitric acid (N-ACF) was studied in this research to determine the adsorption performance for 2,4-dichlorophenoxyacetic acid (2,4-D). Subsequently, influence factors, adsorption isotherm models, kinetics and thermodynamic were investigated in a batch system to realize this adsorption. Experimental results showed that ACF modified by 0.1M nitric acid had a better removal ability than 2,4-D. Removal rate of 2,4-D by N-ACF was greatly influenced by pH with the optimum pH at 2. The superiority of the Langmuir isotherm model in describing the adsorption equilibrium was revealed by correlation coefficients R2 (R 2  ≥ 0.997). Furthermore, adsorption kinetics was well described by pseudo-second-order model. The results of thermodynamic showed that adsorption was a spontaneous, endothermic process with randomness increasing. Additionally, surface structure properties of adsorbent were characterized by Scanning electron microscopy, Fourier transform infrared spectroscopy, Specific surface area analysis of Brunauer, Emmett and Teller and Boehm's titration. It turned out that the micropore structure and functional groups on N-ACF all can contribute to the removal of 2,4-D.

Isolation and identification of calcium-chelating peptides from Pacific cod skin gelatin and their binding properties with calcium.

PubMed

Wu, Wenfei; Li, Bafang; Hou, Hu; Zhang, Hongwei; Zhao, Xue

2017-12-13

A calcium-chelating peptide is considered to have the ability to improve calcium absorption. In this study, Pacific cod skin gelatin hydrolysates treated with trypsin for 120 min exhibited higher calcium-chelating activity. Sequential chromatography, involving hydroxyapatite affinity chromatography and reversed phase high performance liquid chromatography, was used for the purification of calcium-chelating peptides. Two novel peptides with the typical characteristics of collagen were sequenced as GDKGESGEAGER and GEKGEGGHR based on LC-HRMS/MS, which showed a high affinity to calcium. Calcium-peptide complexation was further characterized by ESI-MS (MS and MS/MS) and FTIR spectroscopy. The results showed that the complexation of the two peptides with calcium was conducted mainly at the ratio of 1 : 1. The amino terminal group and the peptide bond of the peptide backbone as well as the amino group of the lysine side chain and the carboxylate of the glutamate side chain were the possible calcium binding sites for the two peptides. Meanwhile, several amino acid side chain groups, including the hydroxyl (Ser) and carboxylate (Asp) of GDKGESGEAGER and the imine (His) of GEKGEGGHR, were crucial in the complexation. The arginine residue in GEKGEGGHR also participated in the calcium coordination. Additionally, several active fragments with calcium-chelating activity were obtained using MS/MS spectra, including GDKGESGEAGE, GEAGER, GEK, EKG and KGE. This study suggests that gelatin-derived peptides have the potential to be used as a calcium-chelating ingredient to combat calcium deficiency.

Incorporation of Deoxyribonucleic Acid Precursors by T4 Deoxyribonucleic Acid-Protein Complexes Retained on Glass Fiber Filters

PubMed Central

Miller, Robert C.; Kozinski, Andrzej W.

1970-01-01

Bacteriophage T4 deoxyribonucleic acid (DNA)-protein complexes were retained preferentially on glass fiber filters. DNA polymerase activity in the complex was detected through the incorporation of 3H-labeled DNA precursors. The primer-product DNA hybridized with both phage and Escherichia coli DNA. Density labeling experiments showed that about 30% of incorporated 3H-deoxyadenosine triphosphate was found in DNA which hybridized with phage DNA; this DNA was found to be covalently attached to the primer DNA. PMID:5497903

Synthetic and natural iron chelators: therapeutic potential and clinical use

PubMed Central

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

2013-01-01

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

Yb-doped aluminophosphosilicate ternary fiber with high efficiency and excellent laser stability

NASA Astrophysics Data System (ADS)

Li, Yuwei; Peng, Kun; Zhan, Huan; Liu, Shuang; Ni, Li; Wang, Yuying; Yu, Juan; Wang, Xiaolong; Wang, Jianjun; Jing, Feng; Lin, Aoxiang

2018-03-01

By using chelate precursor doping technique and traditional modified chemical vapor deposition system, we fabricated Yb-doped aluminophosphosilicate (Al2O3-P2O5-SiO2, ternary Yb-APS) large-mode-area fiber and reported on its laser performance. The fiber preform was doped with Al, P and Yb with concentration of ∼8000 ppm, ∼1700 ppm and ∼400 ppm in molar percent, respectively. Tested with master oscillator power amplifier system, the home-made Yb-APS fiber was found to present 1.02 kW at 1061.1 nm with a high slope efficiency of 81.2% and excellent laser stability with power fluctuation less than ±1.1% for over 10 h. Compared with Yb-doped aluminosilicate (Al2O3-SiO2, binary Yb-AS) fiber, the introduction of P2O5 effectively suppressed photodarkening effect even the P/Al ratio is much less than 1, indicating that Yb-APS fiber is a better candidate for high power fiber lasers.

Miniaturized ascorbic acid fuel cells with flexible electrodes made of graphene-coated carbon fiber cloth

NASA Astrophysics Data System (ADS)

Hoshi, Kazuki; Muramatsu, Kazuo; Sumi, Hisato; Nishioka, Yasushiro

2016-04-01

Ascorbic acid (AA) is a biologically friendly compound and exists in many products such as sports drinks, fruit, and even in human blood. Thus, a miniaturized and flexible ascorbic acid fuel cell (AAFC) is expected be a power source for portable or implantable electric devices. In this study, we fabricated an AAFC with anode and cathode dimensions of 3 × 10 mm2 made of a graphene-coated carbon fiber cloth (GCFC) and found that GCFC electrodes significantly improve the power generated by the AAFC. This is because the GCFC has more than two times the effective surface area of a conventional carbon fiber cloth and it can contain more enzymes. The power density of the AAFC in a phosphate buffer solution containing 100 mM AA at room temperature was 34.1 µW/cm2 at 0.46 V. Technical issues in applying the AAFC to portable devices are also discussed.

Magnetic bead-based enzyme-chromogenic substrate system for ultrasensitive colorimetric immunoassay accompanying cascade reaction for enzymatic formation of squaric acid-iron(III) chelate.

PubMed

Lai, Wenqiang; Tang, Dianping; Zhuang, Junyang; Chen, Guonan; Yang, Huanghao

2014-05-20

This work reports on a simple and feasible colorimetric immunoassay with signal amplification for sensitive determination of prostate-specific antigen (PSA, used as a model) at an ultralow concentration by using a new enzyme-chromogenic substrate system. We discovered that glucose oxidase (GOx), the enzyme broadly used in enzyme-linked immunosorbent assay (ELISA), has the ability to stimulate in situ formation of squaric acid (SQA)-iron(III) chelate. GOx-catalyzed oxidization of glucose leads to the formation of gluconic acid and hydrogen peroxide (H2O2). The latter can catalytically oxidize iron(II) to iron(III), which can rapidly (<1 min) coordinate with the SQA. Formation of the iron-squarate complex causes the color of the solution to change from bluish purple to bluish red accompanying the increasing absorbance with the increment of iron(III) concentration. On the basis of the SQA-iron(III) system, a new immunoassay protocol with GOx-labeled anti-PSA detection antibody can be designed for the detection of target PSA on capture antibody-functionalized magnetic immunosensing probe, monitored by recording the color or absorbance (λ = 468 nm) of the generated SQA-iron(III) chelate. The absorbance intensity shows to be dependent on the concentration of target PSA. A linear dependence between the absorbance and target PSA concentration is obtained under optimal conditions in the range from 1.0 pg mL(-1) to 30 ng mL(-1) with a detection limit (LOD) of 0.5 pg mL(-1) (0.5 ppt) estimated at the 3Sblank level. The sensitivity displays to be 3-5 orders of magnitude better than those of most commercialized human PSA ELISA kits. In addition, the developed colorimetric immunoassay was validated by assaying 12 human serum samples, receiving in good accordance with those obtained by the commercialized PSA ELISA kit. Importantly, the SQA-based immunosensing system can be further extended for the detection of other low-abundance proteins or biomarkers by controlling the target

In vitro growth inhibition of mastitis causing bacteria by phenolics and metal chelators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chew, B.P.; Tjoelker, L.W.; Tanaka, T.S.

1985-11-01

Antimicrobial activities of three phenolic compounds and four metal chelators were tested at 0, 250, 500, and 1000 ppm in vitro against four major mastitis-causing bacteria, Streptococcus agalactiae, Staphylococcus aureus, Klebsiella pnuemoniae, and Escherichia coli. Overall, butylated hydroxyanisole and tert-butylhydroquinone showed the greatest antimicrobial activity. These phenolics were bactericidal at 250 to 500 ppm against all four bacteria tested. The butylated hydroxytoluene was bactericidal against the gram-positive bacteria but was ineffective against the coliforms. At 250 ppm, disodium ethylenediaminetetraacetic acid was bactericidal against the gram-positive bacteria but much less effective against the gram-negatives. However, diethylene-triaminepentaacetic acid was more growth inhibitorymore » than ethylenediaminetetraacetic acid against the gram-negative bacteria and especially against Escherichia coli. All other compounds were generally much less effective or ineffective against all four microorganisms. Therefore, butylated hydroxyanisole, butylated hydroxytoluene, tert-butylhydroquinone, ethylenediaminetetraacetic acid, and diethylenetriaminepentaacetic acid may have practical implications in the prevention or treatment of bovine mastitis.« less

Removal of humic acid by a new type of electrical hollow-fiber microfiltration (E-HFMF)

NASA Astrophysics Data System (ADS)

Shang, Ran; Deng, Hui-ping; Hu, Jing-yi

2010-11-01

Low pressure membrane filtration, such as microfiltration, was widely used in the field of drinking water purification in the past few decades. Traditional microfiltration membranes are not efficient enough in the removal of natural organic matters (NOM) from raw water. Moreover, they tend to be fouled by the NOM and the filtration age of the membranes is thus shrinked. To tackle these problems, a new type of electrical hollow-fiber microfiltration module (E-HFMF) was designed. In the E-HFMF module, the hollow-fiber microfiltration membranes were placed into the radialized electrical field which functioned from the centre to the exterior of the cylindrical cavity. The main goal of the present study was to evaluate the efficiency of E-HFMF to remove the humic acid (HA, one of the main components of NOM). According to the parallel tests compared with the traditional microfiltration, the removal rate of humic acid was raised to 70%˜85% in terms of UV-254 and to 60%˜75% in terms of DOC when filtrating with the E-HFMF, while the removal rates of humic acid were 10%˜20% and 1%˜10% respectively when filtrating with the traditional microfiltration. The negative charged humic acid moved to the anode because of the electrophoresis, so few humic acid could be able to permeate through the membrane. The electrophoresis mobility of the humic acid permeating through the traditional microfiltration decreased by 19%, while the same index from the E-HFMF decreased by 75%. This indicated that the electrophoresis played a significant role on removing the humic acid. According to the gel permeate chromatograph analysis, humic acid aggregated in an electric field and thus forms loose and permeable cake layer on the membrane surface, which also relieved membrane fouling. Meanwhile, the negative charged humic acid migrating to the anode at the center minimized the deposition onto the membrane surface, and eliminated the membrane fouling as a result. During the E-HFMF filtration, the

In Vivo Iron-Chelating Activity and Phenolic Profiles of the Angel's Wings Mushroom, Pleurotus porrigens (Higher Basidiomycetes).

PubMed

Khalili, Masoumeh; Ebrahimzadeh, Mohammad Ali; Kosaryan, Mehrnoush

2015-01-01

Pleurotus porrigens is an culinary-medicinal mushroom. It is locally called sadafi and is found in the northern regions of Iran, especially in Mazandaran. This mushroom is used to prepare a variety of local and specialty foods. Because of the phenol and flavonoid contents and the strong iron-chelating activity of this mushroom, it was selected for an assay of in vivo iron-chelating activity. Methanolic extract was administered intraperitoneally to iron-overloaded mice at two dosages (200 and 400 mg/kg/24 hours) for a total of 20 days, with a frequency of 5 times a week for 4 successive weeks. The total iron content was determined by atomic absorption spectroscopy. Plasma Fe3+ content was determined using a kit. Liver sections were stained by hematoxylin and eosin and Perls stain. A significant decrease in the plasma concentration of iron was observed in mice treated with extracts (P < 0.001). The animals showed a dramatic decrease in plasma Fe3+ content when compared with the control group (P < 0.001). Also, Perls stain improved the smaller amount of deposited iron in the liver of iron-overloaded mice treated with the extract. Liver sections revealed a marked reduction in the extent of necrotic hepatocytes, fibrous tissues, and pseudo-lobules. A high-performance liquid chromatography method was developed to simultaneously separate 7 phenolic acids in extract. Rutin (1.784 ± 0.052 mg g(-1) of extract) and p-coumaric acid (1.026 ± 0.043 mg g(-1) of extract) were detected as the main flavonoid and phenolic acids in extract, respectively. The extract exhibited satisfactory potency to chelate excessive iron in mice, potentially offering new natural alternatives to treat patients with iron overload. More studies are needed to determine which compounds are responsible for these biological activities.

Do vitreous fibers break in the lung?

PubMed

Eastes, Walter; Baron, Paul A; Baier, Robert E; Guldberg, Marianne; Potter, Russell

2007-04-01

In order to determine whether breakage of long vitreous fibers in the lung could be responsible for removing significant numbers of these fibers, an intratracheal instillation study was done with a preparation consisting of mostly long fibers of two different types. Following instillation of both fibers, laboratory rats were sacrificed at 6 times up to 14 days. The NK (conventional borosilicate glass) fiber preparation had about 20% short fibers (length < or = 15 microm) initially, and fibers recovered from the lungs remained at that proportion for the entire 14 days. But the HT (a new rock or stone wool) fiber preparation, which had about 5% short fibers initially, jumped to about 50% short fibers at 2 days and remained at that proportion for the rest of the study. The appearance of many short HT fibers where there were few initially is conclusive evidence that these long fibers break, and it explains their rapid removal from the lung. Since the HT fibers dissolve rapidly at acid pH, but slowly at the near neutral pH of the extracellular lung fluid, it is likely that acid attack by phagocytic cells is causing the long fibers to dissolve and break. The long NK fibers dissolve rapidly at neutral pH but slowly at acid pH and thus appear to clear by more or less uniform dissolution without apparent breakage. The long fibers of these two kinds are removed rapidly at about the same rate, but by a different mechanism.

Synergistic effect of chelators and Herbaspirillum sp. GW103 on lead phytoextraction and its induced oxidative stress in Zea mays.

PubMed

Govarthanan, Muthusamy; Kamala-Kannan, Seralathan; Kim, Seol Ah; Seo, Young-Seok; Park, Jung-Hee; Oh, Byung-Taek

2016-10-01

Phytoremediation is an in situ, low-cost strategy for cleanup of the sites contaminated with heavy metals. Experiments were conducted to assess the impact of synthetic chelators and plant growth-promoting rhizosphere bacteria (Herbaspirillum sp. GW103) on heavy metal lead (Pb) uptake in Z. mays cultivated in Pb-contaminated soil. The present study investigated the Pb phytoaccumulation rate and plant antioxidant enzyme activities in Z. mays exposed to 100 mg/kg of PbNO3. The combination of gluconic acid (GA) with Herbaspirillum sp. GW103 treatment showed higher Pb solubility (18.9 mg/kg) compared with other chelators. The chemical chelators showed the significant difference in phytoaccumulation as well as antioxidant enzyme activities. The antioxidant enzymes such as catalase, peroxidase and superoxide dismutase activities changed under Pb stress. The study indicated that increased activity of antioxidant enzymes may play as signal inducers to fight against Pb.

Hydrothermally tailor-made chitosan fiber for micro-solid phase extraction of petroleum acids in crude oils.

PubMed

Zhu, Gang-Tian; Hu, Xiao-Li; He, Sheng; He, Xiao-Mei; Zhu, Shu-Kui; Feng, Yu-Qi

2018-06-05

Tailor-made chitosan fiber was prepared via hydrothermal treatment to serve as a micro-solid phase extraction (micro-SPE) sorbent for the analysis of petroleum acids (PAs) in crude oils. Chitosan fiber, which is commercial and cheap, has a diameter of about 10 μm and a length of a few centimeters. The fibrous property of the sorbent enables the micro-SPE to deal with viscous crude oil samples because of the low back-pressure during extraction, while the abundant hydroxyl groups and amino groups on the surface of chitosan fiber can provide high density of specific sites for adsorption of PAs. Moreover, it was found that hydrothermal treatment at certain conditions could tune the surface properties of chitosan fiber, leading to significant improvement of the capacity of the fiber in adsorption of PAs. Using hydrothermally treated chitosan fiber as sorbent, the micro-SPE was applied to the determination of PAs in crude oils, with the advantages of easy-operation, rapidness and high sensitivity (the limits of detection range from 0.7 ng/g to 5.4 ng/g). Furthermore, coupled with comprehensive two dimensional gas chromatography-mass spectrometry (GC × GCMS), the treated chitosan fiber packed micro-SPE method showed a great potential for comprehensive profiling of PAs in crude oils. Copyright © 2018 Elsevier B.V. All rights reserved.

Desferrithiocin: A Search for Clinically Effective Iron Chelators

PubMed Central

2015-01-01

The successful search for orally active iron chelators to treat transfusional iron-overload diseases, e.g., thalassemia, is overviewed. The critical role of iron in nature as a redox engine is first described, as well as how primitive life forms and humans manage the metal. The problems that derive when iron homeostasis in humans is disrupted and the mechanism of the ensuing damage, uncontrolled Fenton chemistry, are discussed. The solution to the problem, chelator-mediated iron removal, is clear. Design options for the assembly of ligands that sequester and decorporate iron are reviewed, along with the shortcomings of the currently available therapeutics. The rationale for choosing desferrithiocin, a natural product iron chelator (a siderophore), as a platform for structure–activity relationship studies in the search for an orally active iron chelator is thoroughly developed. The study provides an excellent example of how to systematically reengineer a pharmacophore in order to overcome toxicological problems while maintaining iron clearing efficacy and has led to three ligands being evaluated in human clinical trials. PMID:25207964

DFT study of the interaction between DOTA chelator and competitive alkali metal ions.

PubMed

Frimpong, E; Skelton, A A; Honarparvar, B

2017-09-01

1, 4, 7, 10-tetraazacyclododecane-1, 4, 7, 10-tetracetic acid (DOTA) is an important chelator for radiolabeling of pharmaceuticals. The ability of alkali metals found in the body to complex with DOTA and compete with radio metal ions can alter the radiolabeling process. Non-covalent interactions between DOTA complexed with alkali metals Li + , Na + , K + and Rb + , are investigated with density functional theory using B3LYP and ωB97XD functionals. Conformational possibilities of DOTA were explored with a varying number of carboxylic pendant arms of DOTA in close proximity to the ions. It is found that the case in which four arms of DOTA are interacting with ions is more stable than other conformations. The objective of this study is to explore the electronic structure properties upon complexation of alkali metals Li + Na + , K + and Rb + with a DOTA chelator. Interaction energies, relaxation energies, entropies, Gibbs free energies and enthalpies show that the stability of DOTA, complexed with alkali metals decreases down the group of the periodic table. Implicit water solvation affects the complexation of DOTA-ions leading to decreases in the stability of the complexes. NBO analysis through the natural population charges and the second order perturbation theory, revealed a charge transfer between DOTA and alkali metals. Conceptual DFT-based properties such as HOMO/LUMO energies, ΔE HOMO-LUMO and chemical hardness and softness indicated a decrease in the chemical stability of DOTA-alkali metal complexes down the alkali metal series. This study serves as a guide to researchers in the field of organometallic chelators, particularly, radiopharmaceuticals in finding the efficient optimal match between chelators and various metal ions. Copyright © 2017 Elsevier Inc. All rights reserved.

Regulation of the catalytic behavior of pullulanases chelated onto nickel (II)-modified magnetic nanoparticles.

PubMed

Wang, Jianfeng; Liu, Zhongmei; Zhou, Zhemin

2017-06-01

Chelating of pullulanases onto nickel (II)-modified magnetic nanoparticles results in one-step purification and immobilization of pullulanase, and facilitates the commercial application of pullulanase in industrial scale. To improve the catalytic behavior, especially the operational stability, of the nanocatalyst in consecutive batch reactions, we prepared various iminodiacetic acid-modified magnetic nanoparticles differed in surface polarity and spacer length, on which the His6-tagged pullulanases were chelated via nickel ions, and then studied the correlation between the MNPs surface property and the corresponding catalyst behavior. When pullulanases were chelated onto the surface-modified MNPs, the thermostability of all pullulanase derivatives were lower than that of free counterpart, being not relevant to the protein orientation guided by the locality of the His6-tag, but related to the MNPs basal surface polarity and the grafted spacer length. After chelating of pullulanases onto MNPs, there were changes observed in the pH-activity profile and the apparent Michaelis constant toward pullulan. The changing tendencies were mainly dependent on the His6-tagged pullulanase orientation, and the changing extents were tuned by the spacer length. The reusability of pullulanase immobilized by N-terminal His6-tag was higher than that of pullulanase immobilized by C-terminal His6-tag. Moreover, the reusability of the immobilized pullulanase tested increased till grafting polyether amine-400 as spacer-arm, therefore the N-terminal His6-tagged pullulanase chelating MNPs grafted polyether amine-400 gave the best reusability, which retained 60% of initial activity after 18 consecutive cycles with a total reaction time of 9h. Additionally, the correlation analysis of the catalyst behaviors indicated that the reusability was independent from other catalytic properties such as thermostability and substrate affinity. All the results revealed that the catalyst behavior can be

Imprinted polymer-carbon consolidated composite fiber sensor for substrate-selective electrochemical sensing of folic acid.

PubMed

Prasad, Bhim Bali; Madhuri, Rashmi; Tiwari, Mahavir Prasad; Sharma, Piyush Sindhu

2010-05-15

Molecularly imprinted polymers (MIPs) are often electrically insulating materials. Due to the presence of diffusion barrier(s) in between such MIP coating and electrode surface and the absence of a direct path for the conduction of electrons from the binding sites to the electrode, the development of electrochemical sensor is significantly restricted. The direct use of MIPs those possess intrinsic electron-transport properties, is highly limited. These problems are resolved by the design of an original, substrate-selective MIP-fiber sensor that combines conventional insulating MIP and conducting carbon powder in consolidated phase. A layer of conducting carbon particles, arranged orderly as 'carbon strip', is inducted in the polymer for direct electronic conduction. MIP-carbon composite (monolithic fiber) in this work is prepared via in situ free radical polymerization of a new monomer (2,4,6-trisacrylamido-1,3,5-triazine, TAT) and subsequent cross-linkage with ethylene glycol dimethacrylate, in the presence of carbon powder and template (folic acid), at 55 degrees C in a glass capillary. The detection of folic acid with the MIP-fiber sensor was found to be specific and quantitative (detection limit 0.20 ng mL(-1), RSD=1.3%, S/N=3), in aqueous, blood serum and pharmaceutical samples, without any problem of non-specific false-positive contribution and cross-reactivity. 2010 Elsevier B.V. All rights reserved.

Optimized conditions for chelation of yttrium-90-DOTA immunoconjugates.

PubMed

Kukis, D L; DeNardo, S J; DeNardo, G L; O'Donnell, R T; Meares, C F

1998-12-01

Radioimmunotherapy (RIT) with 90Y-labeled immunoconjugates has shown promise in clinical trials. The macrocyclic chelating agent 1,4,7,10-tetraazacyclododecane-N,N',N",N"'-tetraacetic acid (DOTA) binds 90Y with extraordinary stability, minimizing the toxicity of 90Y-DOTA immunoconjugates arising from loss of 90Y to bone. However, reported 90Y-DOTA immunoconjugate product yields have been typically only < or =50%. Improved yields are needed for RIT with 90Y-DOTA immunoconjugates to be practical. (S) 2-[p-(bromoacetamido)benzyl]-DOTA (BAD) was conjugated to the monoclonal antibody Lym-1 via 2-iminothiolane (2IT). The immunoconjugate product, 2IT-BAD-Lym-1, was labeled in excess yttrium in various buffers over a range of concentrations and pH. Kinetic studies were performed in selected buffers to estimate radiolabeling reaction times under prospective radiopharmacy labeling conditions. The effect of temperature on reaction kinetics was examined. Optimal radiolabeling conditions were identified and used in eight radiolabeling experiments with 2IT-BAD-Lym-1 and a second immunoconjugate, DOTA-peptide-chimeric L6, with 248-492 MBq (6.7-13.3 mCi) of 90Y. Ammonium acetate buffer (0.5 M) was associated with the highest uptake of yttrium. On the basis of kinetic data, the time required to chelate 94% of 90Y (four half-times) under prospective radiopharmacy labeling conditions in 0.5 M ammonium acetate was 17-148 min at pH 6.5, but it was only 1-10 min at pH 7.5. Raising the reaction temperature from 25 degrees C to 37 degrees C markedly increased the chelation rate. Optimal radiolabeling conditions were identified as: 30-min reaction time, 0.5 M ammonium acetate buffer, pH 7-7.5 and 37 degrees C. In eight labeling experiments under optimal conditions, a mean product yield (+/- s.d.) of 91%+/-8% was achieved, comparable to iodination yields. The specific activity of final products was 74-130 MBq (2.0-3.5 mCi) of 90Y per mg of monoclonal antibody. The immunoreactivity of 90Y

Effect of Chelating Agents on the Stability of Nano-TiO2 Sol Particles for Sol-Gel Coating.

PubMed

Maeng, Wan Young; Yoo, Mi

2015-11-01

Agglomeration of sol particles in a titanium alkoxide (tetrabutyl orthotitanate (TBOT), > 97%) solution during the hydrolysis and condensation steps makes the sol solution difficult to use for synthesizing homogeneous sol-gel coating. Here, we have investigated the effect of stabilizing agents (acetic acid and ethyl acetoacetate (EAcAc)) on the agglomeration of Ti alkoxide particles during hydrolysis and condensation in order to determine the optimized conditions for controlling the precipitation of TiO2 particles. The study was conducted at R(AC) ([acetic acid]/[TBOT]) = 0.1-5 and R(EAcAc)([EAcAc]/[TBOT]) = 0.05-0.65. We also studied the effects of a basic catalyst ethanolamine (ETA), water, and HCl on sol stability. The chelating ligands in the precursor sol were analyzed with FT-IR. The coating properties were examined by focused ion beam. The stabilizing agents (acetic acid and EAcAc) significantly influenced the agglomeration and precipitation of TBOT precursor particles during hydrolysis. As R(AC) and R(EAcAc) increased, the agglomeration remarkably decreased. The stability of the sol with acetic acid and EAcAc arises from the coordination of the chelating ligand to TBOT that hinders hydrolysis and condensation. A uniform fine coating (thickness: 30 nm) on stainless steel was obtained by using an optimized sol with R(AC) = 0.5 and R(EAcAc) = 0.65.

Combinational chelation therapy abrogates lead-induced neurodegeneration in rats.

PubMed

Pachauri, Vidhu; Saxena, Geetu; Mehta, Ashish; Mishra, Deepshikha; Flora, Swaran J S

2009-10-15

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

A hollow-fiber membrane extraction process for recovery and separation of lactic acid from aqueous solution.

PubMed

Huang, Hanjing; Yang, Shang-Tian; Ramey, David E

2004-01-01

An energy-efficient hollow-fiber membrane extraction process was successfully developed to separate and recover lactic acid produced in fermentation. Although many fermentation processes have been developed for lactic acid production, an economical method for lactic acid recovery from the fermentation broth is still needed. Continuous extraction of lactic acid from a simulated aqueous stream was achieved by using Alamine 336 in 2-octanol contained in a hollow-fiber membrane extractor. In this process, the extractant was simultaneously regenerated by stripping with NaOH in a second membrane extractor, and the final product is a concentrated lactate salt solution. The extraction rate increased linearly with an increase in the Alamine 336 content in the solvent (from 5 to 40%). Increasing the concentration of the undissociated lactic acid in the feed solution by either increasing the lactate concentration (from 5 to 40 g/L) or decreasing the solution pH (from 5.0 to 4.0) also increased the extraction rate. Based on these observations, a reactive extraction model with a first-order reaction mechanism for both lactic acid and amine concentrations was proposed. The extraction rate also increased with an increase in the feed flow rate, but not the flow rates of solvent and the stripping solution, suggesting that the process was not limited by diffusion in the liquid films or membrane pores. A mathematical model considering both diffusion and chemical reaction in the extractor and back extractor was developed to simulate the process. The model fits the experimental data well and can be used in scale up design of the process.

Performance of Nonmigratory Iron Chelating Active Packaging Materials in Viscous Model Food Systems.

PubMed

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

2015-09-01

Many packaged food products undergo quality deterioration due to iron promoted oxidative reactions. Recently, we have developed a nonmigratory iron chelating active packaging material that represents a novel approach to inhibit oxidation of foods while addressing consumer demands for "cleanˮ labels. A challenge to the field of nonmigratory active packaging is ensuring that surface-immobilized active agents retain activity in a true food system despite diffusional limitations. Yet, the relationship between food viscosity and nonmigratory active packaging activity retention has never been characterized. The objective of this study was to investigate the influence of food viscosity on iron chelation by a nonmigratory iron chelating active packaging material. Methyl cellulose was added to aqueous buffered iron solutions to yield model systems with viscosities ranging from ∼1 to ∼10(5)  mPa·s, representing viscosities ranging from beverage to mayonnaise. Iron chelation was quantified by material-bound iron content using colorimetry and inductively coupled plasma-optical emission spectrometry (ICP-OES).  Maximum iron chelation was reached in solutions up to viscosity ∼10(2)  mPa·s. In more viscous solutions (up to ∼10(4)  mPa·s), there was a significant decrease in iron chelating capacity (P < 0.05). However, materials still retained at least 76% iron chelating capacity. Additionally, the influence of different food hydrocolloids on the performance of nonmigratory iron chelating active packaging was characterized. Methyl cellulose and carrageenan did not compete with the material for specific iron chelation (P > 0.05). Materials retained 32% to 45% chelating capacity when in contact with competitively chelating hydrocolloids guar gum, locust bean gum, and xanthan gum. This work demonstrates the potential application of nonmigratory iron chelating active packaging in liquid and semi-liquid foods to allow for the removal of synthetic chelators, while

Thulium fiber laser lithotripsy using tapered fibers.

PubMed

Blackmon, Richard L; Irby, Pierce B; Fried, Nathaniel M

2010-01-01

The Thulium fiber laser has recently been tested as a potential alternative to the Holmium:YAG laser for lithotripsy. This study explores use of a short taper for expanding the Thulium fiber laser beam at the distal tip of a small-core fiber. Thulium fiber laser radiation with a wavelength of 1,908 nm, 10 Hz pulse rate, 70 mJ pulse energy, and 1-millisecond pulse duration was delivered through a 2-m-length fiber with 150-microm-core-input-end, 300-microm-core-output-end, and 5-mm-length taper, in contact with human uric acid (UA) and calcium oxalate monohydrate (COM) stones, ex vivo (n = 10 each). Stone mass loss, stone crater depths, fiber transmission losses, fiber burn-back, irrigation rates, and deflection through a flexible ureteroscope were measured for the tapered fiber and compared with conventional fibers. After delivery of 1,800 pulses through the tapered fiber, mass loss measured 12.7+/-2.6 mg for UA and 7.2+/-0.8 mg COM stones, comparable to conventional 100-microm-core fibers (12.6+/-2.5 mg for UA and 6.8+/-1.7 mg for COM stones). No transmission losses or burn-back occurred for the tapered fiber after 36,000 pulses, while a conventional 150-microm fiber experienced significant tip degradation after only 1,800 pulses. High irrigation rates were measured with the tapered fiber inserted through the working port of a flexible ureteroscope without hindering its deflection, mimicking that of a conventional 150 microm fiber. The short tapered distal fiber tip allows expansion of the laser beam, resulting in decreased fiber tip damage compared to conventional small-core fibers, without compromising fiber bending, stone vaporization efficiency, or irrigation rates.

Method of carbonizing polyacrylonitrile fibers

NASA Technical Reports Server (NTRS)

Cagliostro, D. E.; Lerner, N. R. (Inventor)

1983-01-01

This invention relates to a method of carbonizing polyacrylonitrile fibers by exposing the fibers at an elevated temperature to an oxidizing atmosphere; then exposing the oxidized fibers to an atmosphere of an inert gas such as nitrogen containing a carbonaceous material such as acetylene. The fibers are preferably treated with an organic compound, for example benzoic acid, before the exposure to an oxidizing atmosphere. The invention also relates to the resulting fibers. The treated fibers have enhanced tensile strength.

Targeting hypoxia in tumors using 2-nitroimidazoles with peptidic chelators for technetium-99m: effect of lipophilicity.

PubMed

Zhang, X; Su, Z F; Ballinger, J R; Rauth, A M; Pollak, A; Thornback, J R

2000-01-01

Tumor hypoxia is an important prognostic factor for response to therapy. Radiolabeled 2-nitroimidazoles have been used for imaging hypoxia, and the octanol/water partition coefficient (P) of these compounds appears to play a crucial role in their suitability for imaging. A series of 11 2-nitroimidazoles coupled to peptidic chelators for (99m)Tc with divergent P was developed and evaluated in an in vitro system. Two classes of N(3)S chelators were used: dialkyl-Gly-Ser-Cys-linker-2-nitroimidazole (Class I) and dialkyl-Gly-Lys(2-nitroimidazole)-Cys (Class II). The chelators were prepared by automated solid-phase peptide synthesis. Xanthine oxidase was able to reduce the 2-nitroimidiazole moiety on the ligands, but the rate of reduction varied 5-fold among the different chelators. The chelators were labeled by transchelation from [(99m)Tc]gluconate at temperatures between 22 and 100 degrees C. The reaction mixtures were analyzed by HPLC and their P values determined. The accumulation of each complex in suspension cultures of Chinese hamster ovary cells incubated under aerobic or extremely hypoxic conditions was determined. Radiochemical yields ranged from 5 to 80% for the 11 compounds. HPLC showed that some of the compounds formed two complexes with (99m)Tc, possibly syn and anti conformations with respect to the Tc=O bond. In general, the Class I chelators labeled more readily than the class II chelators. The P values of the (99m)Tc complexes varied from 0.0002 to 5 and were generally in accordance with predictions based on structure. There were also differences in P as a function of pH; the free acids had a lower P at pH 7.4 than at pH 2.0 due to ionization, whereas the amides did not show this effect. Accumulation levels in aerobic cells were related to P but varied over a narrow range. Four of the 11 compounds showed selective accumulation in hypoxic cells. The peptidic class of 2-nitroimidazoles, with flexible design and convenient solid-phase synthesis, deserves

Process for the manufacture of carbon or graphite fibers

NASA Technical Reports Server (NTRS)

Overhoff, D.; Winkler, E.; Mueller, D.

1979-01-01

Carbon or graphite fibers are manufactured by heating polyacrylonitrile fiber materials in various solutions and gases. They are characterized in that the materials are heated to temperatures from 150 to 300 C in a solution containing one or more acids from the group of carbonic acids, sulfonic acids, and/or phenols. The original molecular orientation of the fibers is preserved by the cyclization that occurs before interlacing, which gives very strong and stiff carbon or graphite fibers without additional high temperature stretching treatments.

Chelating DTPA amphiphiles: ion-tunable self-assembly structures and gadolinium complexes.

PubMed

Moghaddam, Minoo J; de Campo, Liliana; Kirby, Nigel; Drummond, Calum J

2012-10-05

A series of chelating amphiphiles and their gadolinium (Gd(III)) metal complexes have been synthesized and studied with respect to their neat and lyotropic liquid crystalline phase behavior. These amphiphiles have the ability to form ion-tunable self-assembly nanostructures and their associated Gd(III) complexes have potential as magnetic resonance imaging (MRI) contrast enhancement agents. The amphiphiles are composed of diethylenetriaminepentaacetic acid (DTPA) chelates conjugated to one or two oleyl chain(s) (DTPA-MO and DTPA-BO), or isoprenoid-type chain(s) of phytanyl (DTPA-MP and DTPA-BP). The thermal phase behavior of the neat amphiphiles was examined by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and cross polarizing optical microscopy (POM). Self-assembly of neat amphiphiles and their associated Gd complexes, as well as their lyotropic phase behavior in water and sodium acetate solutions of different ionic strengths, were examined by POM and small and wide angle X-ray scattering (SWAXS). All neat amphiphiles exhibited lamellar structures. The non-complexed amphiphiles showed a variety of lyotropic phases depending on the number and nature of the hydrophobic chain in addition to the ionic state of the hydration. Upon hydration with increased Na-acetate concentration and the subtle changes in the effective headgroup size, the interfacial curvature of the amphiphile increased, altering the lyotropic liquid crystalline structures towards higher order mesophases such as the gyroid (Ia3d) bicontinuous cubic phase. The chelation of Gd with the DTPA amphiphiles resulted in lamellar crystalline structures for all the neat amphiphiles. Upon hydration with water, the Gd-complexed mono-conjugates formed micellar or vesicular self-assemblies, whilst the bis-conjugates transformed only partially into lyotropic liquid crystalline mesophases.

Comparing potential copper chelation mechanisms in Parkinson's disease protein

NASA Astrophysics Data System (ADS)

Rose, Frisco; Hodak, Miroslav; Bernholc, Jerry

2011-03-01

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

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

DOEpatents

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.

Structure and in vitro activities of a Copper II-chelating anionic peptide from the venom of the scorpion Tityus stigmurus.

PubMed

Melo, Menilla M A; Daniele-Silva, Alessandra; Teixeira, Diego G; Estrela, Andréia B; Melo, Karolline R T; Oliveira, Verônica S; Rocha, Hugo A O; Ferreira, Leandro de Santis; Pontes, Daniel L; Lima, João P M S; Silva-Júnior, Arnóbio A; Barbosa, Euzebio G; Carvalho, Eneas; Fernandes-Pedrosa, Matheus F

2017-08-01

Anionic Peptides are molecules rich in aspartic acid (Asp) and/or glutamic acid (Glu) residues in the primary structure. This work presents, for the first time, structural characterization and biological activity assays of an anionic peptide from the venom of the scorpion Tityus stigmurus, named TanP. The three-dimensional structure of TanP was obtained by computational modeling and refined by molecular dynamic (MD) simulations. Furthermore, we have performed circular dichroism (CD) analysis to predict TanP secondary structure, and UV-vis spectroscopy to evaluate its chelating activity. CD indicated predominance of random coil conformation in aqueous medium, as well as changes in structure depending on pH and temperature. TanP has chelating activity on copper ions, which modified the peptide's secondary structure. These results were corroborated by MD data. The molar ratio of binding (TanP:copper) depends on the concentration of peptide: at lower TanP concentration, the molar ratio was 1:5 (TanP:Cu 2+ ), whereas in concentrated TanP solution, the molar ratio was 1:3 (TanP:Cu 2+ ). TanP was not cytotoxic to non-neoplastic or cancer cell lines, and showed an ability to inhibit the in vitro release of nitric oxide by LPS-stimulated macrophages. Altogether, the results suggest TanP is a promising peptide for therapeutic application as a chelating agent. Copyright © 2017 Elsevier Inc. All rights reserved.

Assessment on proximate composition, dietary fiber, phytic acid and protein hydrolysis of germinated Ecuatorian brown rice.

PubMed

Cáceres, Patricio J; Martínez-Villaluenga, Cristina; Amigo, Lourdes; Frias, Juana

2014-09-01

Germinated brown rice (GBR) is considered healthier than brown rice (BR) but its nutritive value has been hardly studied. Since nutritive quality of GBR depends on genetic diversity and germination conditions, six Ecuadorian BR varieties were germinated at 28 and 34 ºC for 48 and 96 h in darkness and proximate composition, dietary fiber fractions, phytic acid content as well as degree of protein hydrolysis and peptide content were studied. Protein, lipids, ash and available carbohydrate ranged 7.3-10.4%, 2.0-4.0%, 0.8-1.5% and 71.6 to 84.0%, respectively, in GBR seedlings. Total dietary fiber increased during germination (6.1-13.6%), with a large proportion of insoluble fraction, while phytic acid was reduced noticeably. In general, protein hydrolysis occurred during germination was more accused at 28 ºC for 48 h. These results suggest that GBR can be consumed directly as nutritive staple food for a large population worldwide contributing to their nutritional requirements.

Residual Tensile Property of Plain Woven Jute Fiber/Poly(Lactic Acid) Green Composites during Thermal Cycling

PubMed Central

Katogi, Hideaki; Takemura, Kenichi; Akiyama, Motoki

2016-01-01

This study investigated the residual tensile properties of plain woven jute fiber reinforced poly(lactic acid) (PLA) during thermal cycling. Temperature ranges of thermal cycling tests were 35–45 °C and 35–55 °C. The maximum number of cycles was 103 cycles. The quasi-static tensile tests of jute fiber, PLA, and composite were conducted after thermal cycling tests. Thermal mechanical analyses of jute fiber and PLA were conducted after thermal cycling tests. Results led to the following conclusions. For temperatures of 35–45 °C, tensile strength of composite at 103 cycles decreased 10% compared to that of composite at 0 cycles. For temperatures of 35–55 °C, tensile strength and Young’s modulus of composite at 103 cycles decreased 15% and 10%, respectively, compared to that of composite at 0 cycles. Tensile properties and the coefficient of linear expansion of PLA and jute fiber remained almost unchanged after thermal cycling tests. From observation of a fracture surface, the length of fiber pull out in the fracture surface of composite at 103 cycles was longer than that of composite at 0 cycles. Therefore, tensile properties of the composite during thermal cycling were decreased, probably because of the decrease of interfacial adhesion between the fiber and resin. PMID:28773694

Effects of fiber/matrix interactions on the interfacial deformation micromechanics of cellulose-fiber/polymer composites

NASA Astrophysics Data System (ADS)

Tze, William Tai-Yin

The overall objective of this dissertation was to gain an understanding of the relationship between interfacial chemistry and the micromechanics of the cellulose-fiber/polymer composites. Regenerated cellulose (lyocell) fibers were treated with amine-, phenylamine-, phenyl-, and octadecyl-silanes, and also styrene-maleic anhydride copolymer. Inverse gas chromatography was conducted to evaluate the modified surfaces and to examine the adsorption behavior of ethylbenzene, a model compound for polystyrene, onto the fibers. Micro-composites were formed by depositing micro-droplets of polystyrene onto single fibers. The fiber was subjected to a tensile strain, and Raman spectroscopy was employed to determine the point-to-point variation of the strain- and stress-sensitive 895 cm-1 band of cellulose along the embedded region. Inverse gas chromatography studies reveal that the Ia-b values, calculated by matching the Lewis acid parameter ( KA) and basic parameter (KB) between polystyrene and different fibers, were closely correlated to the acid-base adsorption enthalpies of ethylbenzene onto the corresponding fibers. Hence, Ia-b was subsequently used as a convenient indicator for fiber/matrix acid-base interaction. The Raman micro-spectroscopic studies demonstrate that the interfacial tensile strain and stress are highest at the edge of the droplet, and these values decline from the edge region to the middle region of the embedment. The maximum of these local strains corresponds to a strain-control fracture of the matrix polymer. The minimum of the local tensile stress corresponds to the extent of fiber-to-matrix load transfer. The slope of the tensile stress profile allows for an estimation of the maximum interfacial shear stress, which is indicative of fiber/polymer (practical) adhesion. As such, a novel micro-Raman tensile technique was established for evaluating the ductile-fiber/brittle-polymer system in this study. The micro-Raman tensile technique provided maximum

Surface decoration of polyimide fiber with carbon nanotubes and its application for mechanical enhancement of phosphoric acid-based geopolymers

NASA Astrophysics Data System (ADS)

Yang, Tao; Han, Enlin; Wang, Xiaodong; Wu, Dezhen

2017-09-01

A new methodology to decorate the surface of polyimide (PI) fiber with carbon nanotubes (CNTs) has been developed in this study. This surface decoration was carried out through a surface alkali treatment, a carboxylation modification, surface functionalization with acyl chloride groups and then with amino groups, and a surface graft of CNTs onto PI fiber. Fourier-transform infrared and X-ray photoelectron spectroscopic characterizations confirmed that CNTs were chemically grafted onto the surface of PI fiber, and scanning electron microscopic observation demonstrated the fiber surface was uniformly and densely covered with CNTs. The surface energy and wettability of PI fiber were improved in the presence of CNTs on the fiber surface, which made a contribution to enhance the interfacial adhesion of PI fiber with other inorganic matrices when used as a reinforcing fiber. The application of CNTs-decorated PI fiber for the reinforcement of phosphoric acid-based geopolymers was investigated, and the results indicated that the geopolymeric composites gained a noticeable reinforcement. Compared to unreinforced geopolymer, the geopolymeric composites achieved a remarkable increase in compressive strength by 120% and in flexural strength by 283%. Fractography investigation demonstrated that the interaction adhesion between the fibers and matrix was enhanced due to the surface decoration of PI fiber with CNTs, which contributed to an improvement in fracture-energy dissipation by fiber pullout and fiber debonding from the matrix. As a result, a significant reinforcement effect on geopolymeric composites was achieved through a fiber-bridging mechanism. This study provided an effective methodology to improve the interracial bonding force for PI fiber and also proves a highly efficient application of CNTs-decorated PI fiber for the mechanical enhancement of geopolymeric composites.

Kinetically and thermodynamically stable isomers of thorium chelates of polyaza polycarboxylic macrocycles

NASA Astrophysics Data System (ADS)

Jacques, Vincent; Desreux, Jean F.

1994-10-01

The solution conformation of the thorium(IV) complexes of two polyaza polycarboxylic macrocycles, DOTA and HEHA (1,4,7,10-tetraazacyclododecane-N, N', N(double prime), N(triple prime)-tetraacetic acid and 1,4,7,10,13,16-hexaazacyclooctadecane-N, N', N(double prime), N(triple prime), N(double prime)(double prime), N(double prime)(triple prime)-hexaacetic acid), was investigated by one- and two-dimensional nuclear magnetic resonance spectroscopy. ThHEHA(2+) forms a kinetically stable topomer of C2 symmetry and a thermodynamically stable topomer of S6 symmetry. Both complexes are assigned an icosahedral geometry. The activation energy for the intermolecular exchange is very high (214 kJ/mol). The behavior of ThHEHA(2+) contrasts with the properties of the other Th(IV) chelates that are known to be fluxional.

The influence of functional groups on the permeation and distribution of antimycobacterial rhodamine chelators.

PubMed

Moniz, T; Leite, A; Silva, T; Gameiro, P; Gomes, M S; de Castro, B; Rangel, M

2017-10-01

We formerly hypothesized a mechanism whereby the antimycobacterial efficiency of a set of rhodamine labelled iron chelators is improved via the rhodamine fluorophore which enhances the chelators' permeation properties through membranes. To validate our hypothesis in a cellular context and to understand the influence of the structure of the fluorophore on the chelator's uptake and distribution within macrophages we now report comparative confocal microscopy studies performed with a set of rhodamine labelled chelators. We identify the functional groups of the chelator's framework that favor uptake by macrophages and conclude that the antimycobacterial effect is strongly related with the capacity of the chelator to distribute within the host cell and its compartments, a property that is closely related with the chelators' ability to interact with membranes. The quantification of the chelators' interaction with membranes was assessed through measurement of the corresponding partition constants in liposomes. The overall results support that the compounds which are preferentially taken up are the most efficient antimycobacterial chelators and for that reason we infer that the biological activity is modulated by the structural features of the fluorophore. Copyright © 2017 Elsevier Inc. All rights reserved.

Molecular shuttle chelation: the use of ascorbate, desferrioxamine and Feralex-G in combination to remove nuclear bound aluminum.

PubMed

Kruck, Theo P; Cui, Jian-Guo; Percy, Maire E; Lukiw, Walter J

2004-06-01

1. Abundant data suggest that aluminum (Al(III)) exposure may be an environmental risk factor contributing to the development, progression and/or neuropathology of several human neurodegenerative disorders, including Alzheimer's disease (AD). 2. Nuclei appear to be one directed target for Al(III) binding, accumulation, and Al(III)-mediated dysfunction due in part to their high content of polyphosphorylated nucleic acids, nucleotides, and nucleoproteins. 3. The design of chelation therapies dealing with the removal of Al(III) from these genetic compartments therefore represents an attractive strategy to alleviate the development and/or progression of central nervous system dysfunction that may arise from excessive Al(III) exposure. 4. In this study we have investigated the potential application of 10 natural and synthetic Al(III) chelators, including ascorbate (AS), desferrioxamine (DF), and Feralex-G (FG), used either alone or in combination, to remove Al(III) preincubated with intact human brain cell nuclei. 5. Although nuclear bound Al(III) was found to be highly refractory to removal, the combination of AS+FG was found to be particularly effective in removing Al(III) from the nuclear matrix. 6. Our data suggest that chelators carrying cis-hydroxy ketone groups, such as FG, are particularly suited to the removal of Al(III) from complex biological systems. 7. We further suggest a mechanism whereby small chelating molecules may penetrate the nucleus, bind Al(III), diffuse to regions accessible by the larger DF or FG molecules and transfer their Al(III) to DF or FG. 8. The proposed mechanism, called molecular shuttle chelation may provide a useful pharmacotherapy in the potential treatment of Al(III) overload disease.

Theoretical analysis of the influence of chelate-ring size and vicinal effects on electronic circular dichroism spectra of cobalt(III) EDDA-type complexes.

PubMed

Wang, Ai; Wang, Yuekui; Jia, Jie; Feng, Lixia; Zhang, Chunxia; Liu, Linlin

2013-06-20

To assess the contributions of configurational and vicinal effects as well as chelate-ring size to rotational strengths, the geometries of a series of cobalt(III) complexes [Co(EDDA-type)(L)](±) with the tetradentate EDDA-type ligands, EDDA (ethylenediamine-N,N'-diacetate), DMEDDA (N,N'-dimethylethylenediamine-N,N'-diacetate), DEEDDA (N,N'-diethylethylenediamine-N,N'-diacetate), and a bidentate ancillary ligand L (L = ethylenediamine, oxalate, carbonate, (S)-alanine, and malonate) in aqueous solution have been optimized at the DFT/B3LYP/6-311++G(2d,p) level of theory. Based on the optimized geometries, the excitation energies and oscillator and rotational strengths have been calculated using the time-dependent density functional theory (TDDFT) method with the same functional and basis set. The calculated circular dichroism (CD) curves are in excellent agreement with the observed ones except for some small red or blue shifts in peak wavelengths. For the influence of chelate-ring size of the bidentate ligands on the CD intensities, a qualitative analysis together with the quantitative TDDFT calculation reveal that it depends on the symmetry of the cobalt-EDDA backbone. For the s-cis-isomers, the influence is negligible due to the perturbation is symmetric. For the uns-cis-isomers, the perturbation is unsymmetric. Since a small ring size means a large perturbation, this leads to the integral CD intensities decreasing with increasing the chelate ring size. The vicinal effects of asymmetric nitrogens incorporate both the substitutent effects and conformational relaxation effects, with the former being dominant. By analyzing the contributions of chiral arrays to rotational strengths, we found that the part of contributions dominated by the S-type chiral nitrogens could be considered as a good measure for the vicinal effects of chiral nitrogens. In addition, we found that the twist form (δ/λ) of the backbone ethylenediamine ring (E-ring) of the coordinated EDDA

Electrospining of polyaniline/poly(lactic acid) ultrathin fibers: process and statistical modeling using a non-gaussian approach

USDA-ARS?s Scientific Manuscript database

Cover: The electrospinning technique was employed to obtain conducting nanofibers based on polyaniline and poly(lactic acid). A statistical model was employed to describe how the process factors (solution concentration, applied voltage, and flow rate) govern the fiber dimensions. Nanofibers down to ...

Engineering an antibody with picomolar affinity to DOTA chelates of multiple radionuclides for pretargeted radioimmunotherapy and imaging

PubMed Central

Orcutt, Kelly Davis; Slusarczyk, Adrian L; Cieslewicz, Maryelise; Ruiz-Yi, Benjamin; Bhushan, Kumar R; Frangioni, John V; Wittrup, K Dane

2014-01-01

Introduction In pretargeted radioimmunotherapy (PRIT), a bifunctional antibody is administered and allowed to pre-localize to tumor cells. Subsequently, a chelated radionuclide is administered and captured by cell-bound antibody while unbound hapten clears rapidly from the body. We aim to engineer high-affinity binders to DOTA chelates for use in PRIT applications. Methods We mathematically modeled antibody and hapten pharmacokinetics to analyze hapten tumor retention as a function of hapten binding affinity. Motivated by model predictions, we used directed evolution and yeast surface display to affinity mature the 2D12.5 antibody to 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA), reformatted as a single chain variable fragment (scFv). Results Modeling predicts that for high antigen density and saturating bsAb dose, a hapten binding affinity of 100 picomolar (pM) is needed for near-maximal hapten retention. We affinity matured 2D12.5 with an initial binding constant of about 10 nanomolar (nM) to DOTA-yttrium chelates. Affinity maturation resulted in a 1000-fold affinity improvement to biotinylated DOTA-yttrium, yielding an 8.2 ± 1.9 picomolar binder. The high-affinity scFv binds DOTA complexes of lutetium and gadolinium with similar picomolar affinity and indium chelates with low nanomolar affinity. When engineered into a bispecific antibody construct targeting carcinoembryonic antigen (CEA), pretargeted high-affinity scFv results in significantly higher tumor retention of a 111In-DOTA hapten compared to pretargeted wild-type scFv in a xenograft mouse model. Conclusions We have engineered a versatile, high-affinity DOTA-chelate-binding scFv. We anticipate it will prove useful in developing pretargeted imaging and therapy protocols to exploit the potential of a variety of radiometals. PMID:21315278

Fiber

MedlinePlus

... short period of time can cause intestinal gas ( flatulence ), bloating , and abdominal cramps . This problem often goes ... 213. National Research Council. Dietary reference intakes for energy, carbohydrate, fiber, fat, fatty acids, cholesterol, protein, and ...

Label-free DNA biosensor based on a peptide nucleic acid-functionalized microstructured optical fiber-Bragg grating

NASA Astrophysics Data System (ADS)

Candiani, Alessandro; Bertucci, Alessandro; Giannetti, Sara; Konstantaki, Maria; Manicardi, Alex; Pissadakis, Stavros; Cucinotta, Annamaria; Corradini, Roberto; Selleri, Stefano

2013-05-01

We describe a novel sensing approach based on a functionalized microstructured optical fiber-Bragg grating for specific DNA target sequences detection. The inner surface of a microstructured fiber, where a Bragg grating was previously inscribed, has been functionalized by covalent linking of a peptide nucleic acid probe targeting a DNA sequence bearing a single point mutation implicated in cystic fibrosis (CF) disease. A solution of an oligonucleotide (ON) corresponding to a tract of the CF gene containing the mutated DNA has been infiltrated inside the fiber capillaries and allowed to hybridize to the fiber surface according to the Watson-Crick pairing. In order to achieve signal amplification, ON-functionalized gold nanoparticles were then infiltrated and used in a sandwich-like assay. Experimental measurements show a clear shift of the reflected high order mode of a Bragg grating for a 100 nM DNA solution, and fluorescence measurements have confirmed the successful hybridization. Several experiments have been carried out on the same fiber using the identical concentration, showing the same modulation trend, suggesting the possibility of the reuse of the sensor. Measurements have also been made using a 100 nM mismatched DNA solution, containing a single nucleotide mutation and corresponding to the wild-type gene, and the results demonstrate the high selectivity of the sensor.

Inorganic Nitrate Mimics Exercise-Stimulated Muscular Fiber-Type Switching and Myokine and γ-Aminobutyric Acid Release.

PubMed

Roberts, Lee D; Ashmore, Tom; McNally, Ben D; Murfitt, Steven A; Fernandez, Bernadette O; Feelisch, Martin; Lindsay, Ross; Siervo, Mario; Williams, Elizabeth A; Murray, Andrew J; Griffin, Julian L

2017-03-01

Exercise is an effective intervention for the prevention and treatment of type 2 diabetes. Skeletal muscle combines multiple signals that contribute to the beneficial effects of exercise on cardiometabolic health. Inorganic nitrate increases exercise efficiency, tolerance, and performance. The transcriptional regulator peroxisome proliferator-activated receptor γ coactivator 1α (PGC1α) coordinates the exercise-stimulated skeletal muscle fiber-type switch from glycolytic fast-twitch (type IIb) to oxidative slow-twitch (type I) and intermediate (type IIa) fibers, an effect reversed in insulin resistance and diabetes. We found that nitrate induces PGC1α expression and a switch toward type I and IIa fibers in rat muscle and myotubes in vitro. Nitrate induces the release of exercise/PGC1α-dependent myokine FNDC5/irisin and β-aminoisobutyric acid from myotubes and muscle in rats and humans. Both exercise and nitrate stimulated PGC1α-mediated γ-aminobutyric acid (GABA) secretion from muscle. Circulating GABA concentrations were increased in exercising mice and nitrate-treated rats and humans; thus, GABA may function as an exercise/PGC1α-mediated myokine-like small molecule. Moreover, nitrate increased circulating growth hormone levels in humans and rodents. Nitrate induces physiological responses that mimic exercise training and may underlie the beneficial effects of this metabolite on exercise and cardiometabolic health. © 2017 by the American Diabetes Association.

Iron chelation therapy for transfusional iron overload: a swift evolution.

PubMed

Musallam, Khaled M; Taher, Ali T

2011-01-01

Chronic transfusional iron overload leads to significant morbidity and mortality. While deferoxamine (DFO) is an effective iron chelator with over four decades of experience, it requires tedious subcutaneous infusions that reflect negatively on patient compliance. The novel oral iron chelators deferiprone (L1) and deferasirox (DFRA) opened new horizons for the management of transfusional siderosis. A large body of evidence is now available regarding their efficacy and safety in various populations and settings. Nevertheless, experience with both drugs witnessed some drawbacks, and the search for an ideal and cost-effective iron chelator continues.

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

PubMed

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

2015-07-07

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

Effect of Iron Chelation Therapy on Glucose Metabolism in Non-Transfusion-Dependent Thalassaemia.

PubMed

Chuansumrit, Ampaiwan; Pengpis, Pimprae; Mahachoklertwattana, Pat; Sirachainan, Nongnuch; Poomthavorn, Preamrudee; Sungkarat, Witaya; Kadegasem, Praguywan; Khlairit, Patcharin; Wongwerawattanakoon, Pakawan

2017-01-01

To compare insulin sensitivity, β-cell function and iron status biomarkers in non-transfusion-dependent thalassaemia (NTDT) with iron excess during pre- and post-iron chelation. Subjects with NTDT, aged older than 10 years, with serum ferritin >300 ng/ml, were included. Iron chelation with deferasirox (10 mg/kg/day) was prescribed daily for 6 months. Ten patients with a median age of 17.4 years were enrolled. The comparison between pre- and post-chelation demonstrated significantly lower iron load: median serum ferritin (551.4 vs. 486.2 ng/ml, p = 0.047), median TIBC (211.5 vs. 233.5 µg/dl, p = 0.009) and median non-transferrin binding iron (5.5 vs. 1.4 µM, p = 0.005). All patients had a normal oral glucose tolerance test (OGTT) both pre- and post-chelation. However, fasting plasma glucose was significantly reduced after iron chelation (85.0 vs.79.5 mg/dl, p = 0.047). MRI revealed no significant changes of iron accumulation in the heart and liver after chelation, but there was a significantly lower iron load in the pancreas, assessed by higher T2* at post-chelation compared with pre-chelation (41.9 vs. 36.7 ms, p = 0.047). No adverse events were detected. A trend towards improving insulin sensitivity and β-cell function as well as a reduced pancreatic iron load was observed following 6 months of iron chelation (TCTR20160523003). © 2016 S. Karger AG, Basel.

Function of the iron-binding chelator produced by Coriolus versicolor in lignin biodegradation.

PubMed

Wang, Lu; Yan, WenChao; Chen, JiaChuan; Huang, Feng; Gao, PeiJi

2008-03-01

An ultrafiltered low-molecular-weight preparation of chelating compounds was isolated from a wood-containing culture of the white-rot basidiomycete Coriolus versicolor. This preparation could chelate Fe3+ and reduce Fe3+ to Fe2+, demonstrating that the substance may serve as a ferric chelator, oxygen-reducing agent, and redox-cycling molecule, which would include functioning as the electron transport carrier in Fenton reaction. Lignin was treated with the iron-binding chelator and the changes in structure were investigated by 1H-NMR, 13C-NMR, difference spectrum caused by ionization under alkaline conditions and nitrobenzene oxidation. The results indicated that the iron-binding chelator could destroy the beta-O-4 bonds in etherified lignin units and insert phenolic hydroxyl groups. The low-molecular-weight chelator secreted by C. versicolor resulted in new phenolic substructures in the lignin polymer, making it susceptible to attack by laccase or manganese peroxidase. Thus, the synergic action of the iron-binding chelator and the lignocellulolytic enzymes made the substrate more accessible to degradation.

Detection of Hydrofluoric Acid by a SiO2 Sol-Gel Coating Fiber-Optic Probe Based on Reflection-Based Localized Surface Plasmon Resonance

PubMed Central

Chen, I-Cherng; Lin, Shiu-Shiung; Lin, Tsao-Jen; Du, Je-Kang

2011-01-01

A novel fiber-optic probe based on reflection-based localized surface plasmon resonance (LSPR) was developed to quantify the concentration of hydrofluoric acid (HF) in aqueous solutions. The LSPR sensor was constructed with a gold nanoparticle-modified PMMA fiber, integrated with a SiO2 sol-gel coating. This fiber-sensor was utilized to assess the relationship between HF concentration and SiO2 sol-gel layer etching reduction. The results demonstrated the LSPR sensor was capable of detecting HF-related erosion of hydrofluoric acid solutions of concentrations ranging from 1% to 5% using Relative RI Change Rates. The development of the LSPR sensor constitutes the basis of a detector with significant sensitivity for practical use in monitoring HF solution concentrations. PMID:22319388

Chelation Treatment for Autism Spectrum Disorders: A Systematic Review

ERIC Educational Resources Information Center

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

2013-01-01

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

Copper chelators: chemical properties and bio-medical applications.

PubMed

Tegoni, M; Valensin, D; Toso, L; Remelli, M

2014-01-01

Copper is present in different concentrations and chemical forms throughout the earth crust, surface and deep water and even, in trace amounts, in the atmosphere itself. Copper is one of the first metals used by humans, the first artifacts dating back 10,000 years ago. Currently, the world production of refined copper exceeds 16,000 tons/year. Copper is a micro-element essential to life, principally for its red-ox properties that make it a necessary cofactor for many enzymes, like cytochrome-c oxidase and superoxide dismutase. In some animal species (e.g. octopus, snails, spiders, oysters) copper-hemocyanins also act as carriers of oxygen instead of hemoglobin. However, these red-ox properties also make the pair Cu(+)/Cu(2+) a formidable catalyst for the formation of reactive oxygen species, when copper is present in excess in the body or in tissues. The treatment of choice in cases of copper overloading or intoxication is the chelation therapy. Different molecules are already in clinical use as chelators or under study or clinical trial. It is worth noting that chelation therapy has also been suggested to treat some neurodegenerative diseases or cardiovascular disorders. In this review, after a brief description of the homeostasis and some cases of dyshomeostasis of copper, the main (used or potential) chelators are described; their properties in solution, even in relation to the presence of metal or ligand competitors, under physiological conditions, are discussed. The legislation of the most important Western countries, regarding both the use of chelating agents and the limits of copper in foods, drugs and cosmetics, is also outlined.

Synthesis and thermal characterization of new ternary chelates of piroxicam and tenoxicam with glycine and DL-phenylalanine and some transition metals.

PubMed

Zayed, M A; El-Dien, F A Nour; Mohamed, Gehad G; El-Gamel, Nadia E A

2006-05-01

The ternary chelates of piroxicam (Pir) and tenoxicam (Ten) with Fe(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) in the presence of various amino acids such as glycine (Gly) or dl-phenylalanine (PhA) were prepared and characterized with different physicochemical methods. IR spectra confirm that Pir and Ten behave as a neutral bidentate ligand coordinated to the metal ions via the pyridine-N and carbonyl group of the amide moiety. Gly molecule acted as a uninegatively monodentate ligand and coordinate to the metal ions through its deprotonated carboxylic group. In addition, PhA acted as a uninegatively bidentate ligand and coordinate to the metal ions through its deprotonated carboxylic and amino groups. The solid reflectance spectra and magnetic moment measurements confirm that all the chelates have octahedral geometrical structures while Cu(II)- and Zn(II)-ternary chelates with PhA have square planar geometrical structures. Thermal behaviour of the complexes is extensively studied using TG and DTA techniques. TG results show that water molecules (hydrated and coordinated) and anions are removed in the first and second steps while Gly, PhA, Pir and Ten are decomposed in the next and subsequent steps. The pyrolyses of the chelates into different gases are observed in the DTA curves as exo- or endothermic peaks. Also, phase transition states are observed in some chelates. Different thermodynamic parameters are calculated using Coats-Redfern method and the results are interpreted.

Synthesis and thermal characterization of new ternary chelates of piroxicam and tenoxicam with glycine and DL-phenylalanine and some transition metals

NASA Astrophysics Data System (ADS)

Zayed, M. A.; El-Dien, F. A. Nour; Mohamed, Gehad G.; El-Gamel, Nadia E. A.

2006-05-01

The ternary chelates of piroxicam (Pir) and tenoxicam (Ten) with Fe(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) in the presence of various amino acids such as glycine (Gly) or DL-phenylalanine (PhA) were prepared and characterized with different physicochemical methods. IR spectra confirm that Pir and Ten behave as a neutral bidentate ligand coordinated to the metal ions via the pyridine- N and carbonyl group of the amide moiety. Gly molecule acted as a uninegatively monodentate ligand and coordinate to the metal ions through its deprotonated carboxylic group. In addition, PhA acted as a uninegatively bidentate ligand and coordinate to the metal ions through its deprotonated carboxylic and amino groups. The solid reflectance spectra and magnetic moment measurements confirm that all the chelates have octahedral geometrical structures while Cu(II)- and Zn(II)-ternary chelates with PhA have square planar geometrical structures. Thermal behaviour of the complexes is extensively studied using TG and DTA techniques. TG results show that water molecules (hydrated and coordinated) and anions are removed in the first and second steps while Gly, PhA, Pir and Ten are decomposed in the next and subsequent steps. The pyrolyses of the chelates into different gases are observed in the DTA curves as exo- or endothermic peaks. Also, phase transition states are observed in some chelates. Different thermodynamic parameters are calculated using Coats-Redfern method and the results are interpreted.

A Novel Class of Bis- and Tris-Chelate Diam(m)inebis(dicarboxylato)platinum(IV) Complexes as Potential Anticancer Prodrugs

PubMed Central

Varbanov, Hristo P.; Göschl, Simone; Heffeter, Petra; Theiner, Sarah; Roller, Alexander; Jensen, Frank; Jakupec, Michael A.; Berger, Walter; Galanski, Markus; Keppler, Bernhard K.

2015-01-01

A novel class of platinum(IV) complexes of the type [Pt(Am)-(R(COO)2)2], where Am is a chelating diamine or two monodentate am(m)ine ligands and R(COO)2 is a chelating dicarboxylato moiety, was synthesized. For this purpose, the reaction between the corresponding tetrahydroxidoplatinum(IV) precursors and various dicarboxylic acids, such as oxalic, malonic, 3-methylmalonic, and cyclobutanedicarboxylic acid, was utilized. All new compounds were characterized in detail, using 1D and 2D NMR techniques, ESI-MS, FTIR spectroscopy, elemental analysis, TGA, and X-ray diffraction. Their in vitro cytotoxicity was determined in a panel of human tumor cell lines (CH1, SW480 and A549) by means of the MTT colorimetric assay. Furthermore, the lipophilicity and redox properties of the novel complexes were evaluated in order to better understand their pharmacological behavior. The most promising drug candidate, 4b (Pt(DACH)(mal)2), demonstrated low in vivo toxicity but profound anticancer activity against both the L1210 leukemia and CT-26 colon carcinoma models. PMID:25032896

Quality-of-life outcomes with a disodium EDTA chelation regimen for coronary disease: results from the trial to assess chelation therapy randomized trial.

PubMed

Mark, Daniel B; Anstrom, Kevin J; Clapp-Channing, Nancy E; Knight, J David; Boineau, Robin; Goertz, Christine; Rozema, Theodore C; Liu, Diane M; Nahin, Richard L; Rosenberg, Yves; Drisko, Jeanne; Lee, Kerry L; Lamas, Gervasio A

2014-07-01

The National Institutes of Health.funded Trial to Assess Chelation Therapy (TACT) randomized 1708 stablecoronary disease patients aged .50 years who were .6 months post.myocardial infarction (2003.2010) to 40 infusions ofa multicomponent EDTA chelation solution or placebo. Chelation reduced the primary composite end point of mortality,recurrent myocardial infarction, stroke, coronary revascularization, or hospitalization for angina (hazard ratio, 0.82; 95%confidence interval, 0.69.0.99; P=0.035). In a randomly selected subset of 911 patients, we prospectively collected a battery of quality-of-life(QOL) instruments at baseline and at 6, 12, and 24 months after randomization. The prespecified primary QOL measures were the Duke Activity Status Index (Table I in the Data Supplement) and the Medical Outcomes Study Short-Form 36 Mental Health Inventory-5. All comparisons were by intention to treat. Baseline clinical and QOL variables were well balanced in the 451 patients randomized to chelation and in the 460 patients randomized to placebo. The Duke Activity Status Index improved in both groups during the first 6 months of therapy, but we found no evidence for a treatment-related difference (mean difference [chelation.placebo] during follow-up, 0.9 [95% confidence interval, .0.7 to 2.6; P=0.27]).There was no statistically significant evidence of a treatment-related difference in the Mental Health Inventory-5 during follow-up (mean difference, 1.0; 95% confidence interval, .0.1 to 2.0; P=0.08). None of the secondary QOL measures showed a consistent treatment-related difference. In stable, predominantly asymptomatic coronary disease patients with a history of myocardial infarction,EDTA chelation therapy did not have a detectable effect on QOL during 2 years of follow-up. URL: http://clinicaltrials.gov. Unique identifier: NCT00044213.

The meat quality, muscle fiber characteristics and fatty acid profile in Jinjiang and F1 Simmental×Jinjiang yellow cattle.

PubMed

Zheng, Yue; Wang, Shizhi; Yan, Peishi

2018-02-01

This study compared the meat quality, muscle fiber characteristics, and fatty acids between Jinjiang yellow cattle (JJ) and F1 Simmental×Jinjiang yellow cattle (SJ) which were offered the same diet. Six JJ and six SJ individuals were reared and fattened from 10 to 26 months of age. After feeding, the highrib (HR), ribeye (RB), and tenderloin (TL) samples were taken from the carcass for meat quality evaluations. The results showed that growth performance of SJ was higher than that of JJ (higher live weight and average daily gain), and the hot carcass weight of SJ was higher than that of JJ (p<0.05). pH of JJ was higher than that of SJ in TL (p<0.05); the color of a* of SJ was higher than that of JJ in TL and RB (p<0.05); the cooking loss of SJ was significantly lower than that of JJ in TL and RB (p<0.05); the shear force value was significantly lower in SJ compared to JJ (p<0.05); the muscle fiber diameter was higher and the fiber density was lower in SJ compared to JJ in HR and TL (p<0.05); compared to SJ, the muscles of JJ had higher saturated fatty acid (SFA) composition; the sum of monounsaturated fatty acid and polyunsaturated fatty acid (PUFA) were lower in the muscle of JJ; the mRNA expressions of myosin heavy chain-I (MyHC-I) and MyHC-IIa were higher in SJ compared to JJ in muscle of HR and RB; the mRNA expressions of MyHC-IIx and MyHC-IIb were lower in SJ compared to JJ in HR and RB (p<0.05). Meat quality and fatty acid profile differed between SJ and JJ; the muscle of SJ had higher a* and SFA; SJ had lower cooking loss, shear force and PUFA compared to the muscle of JJ. In addition, the type and development characteristics of the muscle fiber had some difference between SJ and JJ; these might be factors which caused the differences in meat quality and fatty acid profile between SJ and JJ.

The meat quality, muscle fiber characteristics and fatty acid profile in Jinjiang and F1 Simmental×Jinjiang yellow cattle

PubMed Central

Zheng, Yue; Wang, Shizhi

2018-01-01

Objective This study compared the meat quality, muscle fiber characteristics, and fatty acids between Jinjiang yellow cattle (JJ) and F1 Simmental×Jinjiang yellow cattle (SJ) which were offered the same diet. Methods Six JJ and six SJ individuals were reared and fattened from 10 to 26 months of age. After feeding, the highrib (HR), ribeye (RB), and tenderloin (TL) samples were taken from the carcass for meat quality evaluations. Results The results showed that growth performance of SJ was higher than that of JJ (higher live weight and average daily gain), and the hot carcass weight of SJ was higher than that of JJ (p<0.05). pH of JJ was higher than that of SJ in TL (p<0.05); the color of a* of SJ was higher than that of JJ in TL and RB (p<0.05); the cooking loss of SJ was significantly lower than that of JJ in TL and RB (p<0.05); the shear force value was significantly lower in SJ compared to JJ (p<0.05); the muscle fiber diameter was higher and the fiber density was lower in SJ compared to JJ in HR and TL (p<0.05); compared to SJ, the muscles of JJ had higher saturated fatty acid (SFA) composition; the sum of monounsaturated fatty acid and polyunsaturated fatty acid (PUFA) were lower in the muscle of JJ; the mRNA expressions of myosin heavy chain-I (MyHC-I) and MyHC-IIa were higher in SJ compared to JJ in muscle of HR and RB; the mRNA expressions of MyHC-IIx and MyHC-IIb were lower in SJ compared to JJ in HR and RB (p<0.05). Conclusion Meat quality and fatty acid profile differed between SJ and JJ; the muscle of SJ had higher a* and SFA; SJ had lower cooking loss, shear force and PUFA compared to the muscle of JJ. In addition, the type and development characteristics of the muscle fiber had some difference between SJ and JJ; these might be factors which caused the differences in meat quality and fatty acid profile between SJ and JJ. PMID:28823135

Effects of targeting moiety, linker, bifunctional chelator, and molecular charge on biological properties of 64Cu-labeled triphenylphosphonium cations.

PubMed

Kim, Young-Seung; Yang, Chang-Tong; Wang, Jianjun; Wang, Lijun; Li, Zi-Bo; Chen, Xiaoyuan; Liu, Shuang

2008-05-22

In this report, we present the synthesis and evaluation of six new 64Cu-labeled triphenylphosphonium (TPP) cations. Biodistribution studies were performed using the athymic nude mice bearing U87MG human glioma xenografts to explore the impact of TPP moieties, linkers, bifunctional chelators (BFCs), and molecular charge on biological properties of 64Cu radiotracers. On the basis of the results from this study, it is concluded that (1) mTPP (tris(4-methoxyphenyl)phosphonium) is a better mitochondrion-targeting molecule than TPP and 3mTPP (tris(2,4,6-trimethoxyphenyl)phosphonium); (2) DO3A (1,4,7,10-tetraazacyclododecane-4,7,10-triacetic acid) and DO2A (1,4,7,10-tetraazacyclododecane-4,7-diacetic acid) are suitable BFCs for the 64Cu-labeling of TPP cations; (3) NOTA-Bn ( S-2-(4-thioureidobenzyl)-1,4,7-triazacyclononane-1,4,7-triacetic acid) has a significant adverse effect on the radiotracer tumor uptake and tumor-to-background ratios; and (4) monoanionic BFCs should be avoided to ensure that 64Cu chelate has a neutral or negative charge. Considering the tumor uptake and tumor/liver ratios, 64Cu(DO2A-xy-TPP)+ is the best candidate for more extensive evaluations in different tumor-bearing animal models.

Comparison of DOTA and NODAGA as chelators for (64)Cu-labeled immunoconjugates.

PubMed

Ghosh, Sukhen C; Pinkston, Kenneth L; Robinson, Holly; Harvey, Barrett R; Wilganowski, Nathaniel; Gore, Karen; Sevick-Muraca, Eva M; Azhdarinia, Ali

2015-02-01

Bifunctional chelators have been shown to impact the biodistribution of monoclonal antibody (mAb)-based imaging agents. Recently, radiolabeled 1,4,7-triazacyclononane,1-glutaric acid-4,7-acetic acid (NODAGA)-peptide complexes have demonstrated improved in vivo stability and performance compared to their 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) counterparts. Here, we investigated if similar utility could be achieved with mAbs and compared (64)Cu-labeled DOTA and NODAGA-immunoconjugates for the detection of epithelial cell adhesion molecule (EpCAM) in a prostate cancer model. DOTA and NODAGA-immunoconjugates of an EpCAM targeting mAb (mAb7) were synthesized and radiolabeled with (64)Cu (DOTA: 40°C for 1hr; NODAGA: 25°C for 1hr). The average number of chelators per mAb was quantified by isotopic dilution, and the biological activity of the immunoconjugates was evaluated by flow cytometry and ELISA. Radioligand assays were performed to compare cellular uptake and determine the dissociation constant (Kd) and maximum number of binding sites (Bmax) for the immunoconjugates using DsRed-transfected PC3-cells. A PC3-DsRed xenograft tumor model was established in nude mice and used to perform biodistribution studies to compare organ uptake and pharmacokinetics. (64)Cu-DOTA-mAb7 and (64)Cu-NODAGA-mAb7 were prepared with chelator/protein ratios of 2-3 and obtained in comparable radiochemical yields ranging from 59 to 71%. Similar immunoreactivity was observed with both agents, and mock labeling studies indicated that incubation at room temperature or 40°C did not affect potency. (64)Cu-NODAGA-mAb7 demonstrated higher in vitro cellular uptake while (64)Cu-DOTA-mAb7 had higher Kd and Bmax values. From the biodistribution data, we found similar tumor uptake (13.44±1.21%ID/g and 13.24±4.86%ID/g for (64)Cu-DOTA-mAb7 and (64)Cu-NODAGA-mAb7, respectively) for both agents at 24hr, although normal prostate tissue was significantly lower for (64)Cu-NODAGA-mAb7

Polyamine-iron chelator conjugate.

PubMed

Bergeron, Raymond J; McManis, James S; Franklin, April M; Yao, Hua; Weimar, William R

2003-12-04

The current study demonstrates unequivocally that polyamines can serve as vectors for the intracellular delivery of the bidentate chelator 1,2-dimethyl-3-hydroxypyridin-4-one (L1). The polyamine-hydroxypyridinone conjugate 1-(12-amino-4,9-diazadodecyl)-2-methyl-3-hydroxy-4(1H)-pyridinone is assembled from spermine and 3-O-benzylmaltol. The conjugate is shown to form a 3:1 complex with Fe(III) and to be taken up by the polyamine transporter 1900-fold against a concentration gradient. The K(i) of the conjugate is 3.7 microM vs spermidine for the polyamine transporter. The conjugate is also at least 230 times more active in suppressing the growth of L1210 murine leukemia cells than is the parent ligand, decreases the activities of the polyamine biosynthetic enzymes ornithine decarboxylase and S-adenosylmethionine decarboxylase, and upregulates spermidine-spermine N (1)-acetyltransferase. However, the effect on native polyamine pools is a moderate one. These findings are in keeping with the idea that polyamines can also serve as efficient vectors for the intracellular delivery of other iron chelators.

Interaction of chelating agents with cadmium in mice and rats.

PubMed Central

Eybl, V; Sýkora, J; Koutenský, J; Caisová, D; Schwartz, A; Mertl, F

1984-01-01

The influence of several chelating agents (CaDTPA, ZnDTPA, CaEDTA, ZnEDTA, DMSA, D-penicillamine and DMPS, DMP and DDC) on the acute toxicity of CdCl2 and on the whole body retention and tissue distribution of cadmium after the IV application of 115mCdCl2 was compared in mice. The chelating agents were applied immediately after the application of cadmium. CaDTPA, ZnDTPA and DMSA appeared to be the most effective antidotes. However, DMSA increased the amount of cadmium retained in kidneys. The treatment of cadmium-poisoned mice with the combination of DMSA (IP) and ZnDTPA (SC) (all the compounds were injected in equimolar dose) decreased the toxicity of cadmium more than treatment with one chelating agents (given in a 2:1 dose). However, by studying the effect of these chelating agents and their combination of the retention and distribution of Cd in mice, it was demonstrated that the combined application of the antidotes showed little or no improvement over the results obtained with the most effective of the individual components. In the urine of rats injected with CdCl2 and treated with the chelating agents (CaDTPA, ZnDTPA, DMSA), the presence of cadmium complexes was demonstrated. The formation of mixed ligand chelates in vivo was not proved. Experiments in mice given a single injection of 115mCd-labeled Cd complexes of DMPS, DMSA and DTPA showed a high retention of cadmium in the organisms after the IV application of CdDMPS and CdDMSA complexes. PMID:6734561

Evaluation of nitrogen-rich macrocyclic ligands for the chelation of therapeutic bismuth radioisotopes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wilson, Justin J.; Ferrier, Maryline; Radchenko, Valery

The use of α-emitting isotopes for radionuclide therapy is a promising treatment strategy for small micro-metastatic disease. The radioisotope ²¹³Bi is a nuclide that has found substantial use for targeted α-therapy (TAT). The relatively unexplored aqueous chemistry of Bi³⁺, however, hinders the development of bifunctional chelating agents that can successfully deliver these Bi radioisotopes to the tumor cells. Here, a novel series of nitrogen-rich macrocyclic ligands is explored for their potential use as Bi-selective chelating agents. The ligands, 1,4,7,10-tetrakis(pyridin-2-ylmethyl)-1,4,7,10-tetraazacyclododecane (L py), 1,4,7,10-tetrakis(3-pyridazylmethyl)-1,4,7,10-tetraazacyclododecane (L pyd), 1,4,7,10-tetrakis(4-pyrimidylmethyl)-1,4,7,10-tetraazacyclododecane (L pyr), and 1,4,7,10-tetrakis(2-pyrazinylmethyl)-1,4,7,10-tetraazacyclododecane (L pz), were prepared by a previously reported method and investigatedmore » here for their abilities to bind Bi radioisotopes. The commercially available and commonly used ligands 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) and N-[ (R)-2-amino-3-( p-isothiocyanato-phenyl)propyl]- trans-(S,S)- cyclohexane-1,2-diamine- N,N,N',N",N"-pentaacetic acid (CHX-A''-DTPA) were also explored for comparative purposes. Radio-thin-layer chromatography (TLC) was used to measure the binding kinetics and stabilities of the complexes formed. The long-lived isotope, ²⁰⁷Bi (t 1/2 = 32 years), was used for these studies. Density functional theory (DFT) calculations were also employed to probe the ligand interactions with Bi³⁺ and the generator parent ion Ac³⁺.In contrast to DOTA and CHX-A''-DTPA, these nitrogen-rich macrocycles selectively chelate Bi³⁺ in the presence of the parent isotope Ac³⁺. Among the four tested, L py was found to exhibit optimal Bi³⁺-binding kinetics and complex stability. L py complexes Bi³⁺ more rapidly than DOTA, yet the resulting complexes are of similar stability

Evaluation of nitrogen-rich macrocyclic ligands for the chelation of therapeutic bismuth radioisotopes

DOE PAGES

Wilson, Justin J.; Ferrier, Maryline; Radchenko, Valery; ...

2015-05-01

The use of α-emitting isotopes for radionuclide therapy is a promising treatment strategy for small micro-metastatic disease. The radioisotope ²¹³Bi is a nuclide that has found substantial use for targeted α-therapy (TAT). The relatively unexplored aqueous chemistry of Bi³⁺, however, hinders the development of bifunctional chelating agents that can successfully deliver these Bi radioisotopes to the tumor cells. Here, a novel series of nitrogen-rich macrocyclic ligands is explored for their potential use as Bi-selective chelating agents. The ligands, 1,4,7,10-tetrakis(pyridin-2-ylmethyl)-1,4,7,10-tetraazacyclododecane (L py), 1,4,7,10-tetrakis(3-pyridazylmethyl)-1,4,7,10-tetraazacyclododecane (L pyd), 1,4,7,10-tetrakis(4-pyrimidylmethyl)-1,4,7,10-tetraazacyclododecane (L pyr), and 1,4,7,10-tetrakis(2-pyrazinylmethyl)-1,4,7,10-tetraazacyclododecane (L pz), were prepared by a previously reported method and investigatedmore » here for their abilities to bind Bi radioisotopes. The commercially available and commonly used ligands 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) and N-[ (R)-2-amino-3-( p-isothiocyanato-phenyl)propyl]- trans-(S,S)- cyclohexane-1,2-diamine- N,N,N',N",N"-pentaacetic acid (CHX-A''-DTPA) were also explored for comparative purposes. Radio-thin-layer chromatography (TLC) was used to measure the binding kinetics and stabilities of the complexes formed. The long-lived isotope, ²⁰⁷Bi (t 1/2 = 32 years), was used for these studies. Density functional theory (DFT) calculations were also employed to probe the ligand interactions with Bi³⁺ and the generator parent ion Ac³⁺.In contrast to DOTA and CHX-A''-DTPA, these nitrogen-rich macrocycles selectively chelate Bi³⁺ in the presence of the parent isotope Ac³⁺. Among the four tested, L py was found to exhibit optimal Bi³⁺-binding kinetics and complex stability. L py complexes Bi³⁺ more rapidly than DOTA, yet the resulting complexes are of similar stability

Photonic crystal fiber interferometric pH sensor based on polyvinyl alcohol/polyacrylic acid hydrogel coating.

PubMed

Hu, Pengbing; Dong, Xinyong; Wong, Wei Chang; Chen, Li Han; Ni, Kai; Chan, Chi Chiu

2015-04-01

We present a simple photonic crystal fiber interferometer (PCFI) that operates in reflection mode for pH measurement. The sensor is made by coating polyvinyl alcohol/polyacrylic acid (PVA/PAA) hydrogel onto the surface of the PCFI, constructed by splicing a stub of PCF at the distal end of a single-mode fiber with its free end airhole collapsed. The experimental results demonstrate a high average sensitivity of 0.9 nm/pH unit for the 11 wt.% PVA/PAA coated sensor in the pH range from 2.5 to 6.5. The sensor also displays high repeatability and stability and low cross-sensitivity to temperature. Fast, reversible rise and fall times of 12 s and 18 s, respectively, are achieved for the sensor time response.

Odd-chain fatty acids as a biomarker for dietary fiber intake: a novel pathway for endogenous production from propionate.

PubMed

Weitkunat, Karolin; Schumann, Sara; Nickel, Daniela; Hornemann, Silke; Petzke, Klaus J; Schulze, Matthias B; Pfeiffer, Andreas Fh; Klaus, Susanne

2017-06-01

Background: The risk of type 2 diabetes is inversely correlated with plasma concentrations of odd-chain fatty acids [OCFAs; pentadecanoic acid (15:0) and heptadecanoic acid (17:0)], which are considered as biomarkers for dairy fat intake in humans. However, rodent studies suggest that OCFAs are synthesized endogenously from gut-derived propionate. Propionate increases with dietary fiber consumption and has been shown to improve insulin sensitivity. Objective: We hypothesized that OCFAs are produced in humans from dietary fibers by a novel endogenous pathway. Design: In a randomized, double-blind crossover study, 16 healthy individuals were supplemented with cellulose (30 g/d), inulin (30 g/d), or propionate (6 g/d) for 7 d. In addition, human hepatoma cells were incubated with different propionate concentrations. OCFAs were determined in plasma phospholipids and hepatoma cells by gas chromatography. Results: Cellulose did not affect plasma OCFA levels, whereas inulin and propionate increased pentadecanoic acid by ∼17% ( P < 0.05) and 13% ( P = 0.05), respectively. The effect on heptadecanoic acid was even more pronounced, because it was elevated in almost all participants by inulin (11%; P < 0.01) and propionate (13%; P < 0.001). Furthermore, cell culture experiments showed a positive association between propionate and OCFA levels ( R 2 = 0.99, P < 0.0001), whereas palmitate (16:0) was negatively correlated ( R 2 = 0.83, P = 0.004). Conclusions: Our data show that gut-derived propionate is used for the hepatic synthesis of OCFAs in humans. The association of OCFAs with a decreased risk of type 2 diabetes may therefore also relate to dietary fiber intake and not only dairy fat. This trial was registered at www.germanctr.de as DRKS00010121. © 2017 American Society for Nutrition.

Chelation therapy to treat atherosclerosis, particularly in diabetes: Is it time to reconsider?

PubMed Central

Lamas, Gervasio A; Ergui, Ian

2016-01-01

Summary Reports and case series have suggested a possible beneficial effect of chelation therapy in patients with atherosclerotic disease. Small randomized trials conducted in patients with angina or peripheral artery disease, however, were not sufficiently powered to provide conclusive evidence on clinical outcomes. The Trial to Assess Chelation Therapy (TACT) was the first randomized trial adequately powered to detect the effects of chelation therapy on clinical endpoints. Chelation reduced adverse cardiovascular events in a post myocardial infarction (MI) population. Patients with diabetes demonstrated even greater benefit, with a number needed to treat of 6.5 patients to prevent a cardiac event over 5 years. These results led to the revision of the ACC/AHA guideline recommendations for chelation therapy, changing its classification from class III to class IIb. TACT2, a replicative trial, will assess the effects of chelation therapy on cardiovascular outcomes in diabetic patients with a prior myocardial infarction. PMID:27149141

Phenomenon of hot-cold hemolysis: chelator-induced lysis of sphingomyelinase-treated erythrocytes.

PubMed Central

Smyth, C J; Möllby, R; Wadström, T

1975-01-01

Staphylococcus aureus produces a phospholipase C specific for sphingomyelin (beta-hemolysin). Erythrocytes with approximately 50% sphingomyelin in their membranes, e.g., from sheep, have been shown to have up to 60% of this phospholipid hydrolyzed by this enzyme at 37 C in isotonic buffered saline without hemolysis. Cooling of sphingomyelinase C-treated erythrocytes to 4 C causes complete lysis of the cells, a phenomenon known as hot-cold hemolysis. The addition of ethylenediaminetetraacetate (EDTA) to sheep erythrocytes preincubated with sphingomyelinase C was found to induce rapid hemolysis at 37 C. The treated cells became susceptible to chelator-induced hemolysis and to hot-cold hemolysis simultaneously, and the degree of lysis of both mechanisms increased equally with prolonged preincubation with sphingomyelinase C. Erythrocytes of species not readily susceptible to hot-cold hemolysis were equally insusceptible to chelator-induced lysis. Chelators of the EDTA series were the most effective, whereas chelators more specific for Ca2+, Zn2+, Fe2+, Cu2+, and Mg2+ were without effect. The rate of chelator-induced lysis was dependent on the preincubation period with beta-hemolysin and on the concentration of chelator added. The optimal concentration of EDTA was found to equal the amount of exogenously added Mg2+, a cation necessary for sphingomyelinase C activity. Hypotonicity increased the rate of chelator-induced hemolysis, whereas increasing the osmotic pressure to twice isotonic completely inhibited chelator-induced lysis. The data suggest that exogenously added and/or membrane-bound divalent cations are important for the stability of sphingomyelin-depleted membranes. The phenomenon of hot-cold hemolysis may be a consequence of the temperature dependence of divalent ion stabilization. Images PMID:333

Scaffold design of trivalent chelator heads dictates high-affinity and stable His-tagged protein labeling in vitro and in cellulo.

PubMed

Gatterdam, Karl; Joest, Eike F; Gatterdam, Volker; Tampé, Robert

2018-05-29

Small chemical/biological interaction pairs are at the forefront in tracing proteins' function and interaction at high signal-to-background ratio in cellular pathways. Pharma ventures have eager plans to develop trisNTA probes for in vitro and in vivo screening of His-tagged protein targets. However, the optimal design of scaffold, linker, and chelator head yet deserves systematic investigations to achieve highest affinity and kinetic stability for in vitro and especially cell applications. In this study, we report on a library of N-nitrilotriacetic acid (NTA) based multivalent chelator heads (MCHs) built up on linear, cyclic, and dendritic scaffolds and contrast these with regard to their binding affinity and stability for labeling of cellular His-tagged proteins. Furthermore, we assign a new approach for tracing cellular target proteins at picomolar probe concentrations in cells. Finally, we describe fundamental differences between the MCH scaffold and define a cyclic trisNTA chelator, which displays the highest affinity and kinetic stability of all reversible, low-molecular weight interaction pairs. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The Effect of an EDTA-based Chelation Regimen on Patients with Diabetes and Prior Myocardial Infarction in TACT

PubMed Central

Escolar, Esteban; Lamas, Gervasio A.; Mark, Daniel B.; Boineau, Robin; Goertz, Christine; Rosenberg, Yves; Nahin, Richard L.; Ouyang, Pamela; Rozema, Theodore; Magaziner, Allan; Nahas, Richard; Lewis, Eldrin F.; Lindblad, Lauren; Lee, Kerry L.

2014-01-01

Background The Trial to Assess Chelation Therapy (TACT) showed clinical benefit of an ethylene diamine tetraacetic acid (EDTA-based) infusion regimen in patients 50 years or older with prior myocardial infarction (MI). Diabetes prior to enrollment was a pre-specified subgroup. Methods and Results Patients received 40 infusions of EDTA chelation or placebo. 633 (37%) had diabetes (322 EDTA, 311 placebo). EDTA reduced the primary endpoint (death, reinfarction, stroke, coronary revascularization, or hospitalization for angina) [25% vs 38%, hazard ratio (HR) 0.59, 95% confidence interval (CI) (0.44, 0.79), p<0.001] over 5 years. The result remained significant after Bonferroni adjustment for multiple subgroups (99.4% CI (0.39, 0.88), adjusted p=0.002). All-cause mortality was reduced by EDTA chelation [10% vs 16%, HR 0.57, 95% CI (0.36, 0.88) p=0.011], as was the secondary endpoint (cardiovascular death, reinfarction, or stroke) [11% vs 17% HR 0.60, 95% CI (0.39, 0.91), p=0.017]. After adjusting for multiple subgroups, however, those results were no longer significant. The number needed to treat to reduce one primary endpoint was 6.5 over 5 years (95% CI (4.4, 12.7). There was no reduction in events in non-diabetics (n=1075, p=0.877), resulting in a treatment by diabetes interaction (p=0.004). Conclusions Post-MI diabetic patients age 50 or older demonstrated a marked reduction in cardiovascular events with EDTA chelation. These findings support efforts to replicate these findings and define the mechanisms of benefit. They do not, however, constitute sufficient evidence to indicate the routine use of chelation therapy for all post-MI diabetic patients. PMID:24254885

Self-Assembly of Large Amyloid Fibers

NASA Astrophysics Data System (ADS)

Ridgley, Devin M.

Functional amyloids found throughout nature have demonstrated that amyloid fibers are potential industrial biomaterials. This work introduces a new "template plus adder" cooperative mechanism for the spontaneous self-assembly of micrometer sized amyloid fibers. A short hydrophobic template peptide induces a conformation change within a highly alpha-helical adder protein to form beta-sheets that continue to assemble into micrometer sized amyloid fibers. This study utilizes a variety of proteins that have template or adder characteristics which suggests that this mechanism may be employed throughout nature. Depending on the amino acid composition of the proteins used the mixtures form amyloid fibers of a cylindrical ( 10 mum diameter, 2 GPa Young's modulus) or tape (5- 10 mum height, 10-20 mum width and 100-200 MPa Young's modulus) morphology. Processing conditions are altered to manipulate the morphology and structural characteristics of the fibers. Spectroscopy is utilized to identify certain amino acid groups that contribute to the self-assembly process. Aliphatic amino acids (A, I, V and L) are responsible for initiating conformation change of the adder proteins to assemble into amyloid tapes. Additional polyglutamine segments (Q-blocks) within the protein mixtures will form Q hydrogen bonds to reinforce the amyloid structure and form a cylindrical fiber of higher modulus. Atomic force microscopy is utilized to delineate the self-assembly of amyloid tapes and cylindrical fibers from protofibrils (15-30 nm width) to fibers (10-20 mum width) spanning three orders of magnitude. The aliphatic amino acid content of the adder proteins' alpha-helices is a good predictor of high density beta-sheet formation within the protein mixture. Thus, it is possible to predict the propensity of a protein to undergo conformation change into amyloid structures. Finally, Escherichia coli is genetically engineered to express a template protein which self-assembles into large amyloid

Di-macrocyclic terephthalamide ligands as chelators for the PET radionuclide zirconium-89

DOE PAGES

Pandya, Darpan N.; Pailloux, Sylvie; Tatum, David; ...

2014-12-18

The development of bifunctional chelators (BFCs) which can stably chelate zirconium-89 ((89)Zr) while being conjugated to targeting molecules is an area of active research. Herein we report the first octadentate terephthalamide ligands, which are easily radiolabeled with (89)Zr and are highly stable in vitro. Lastly, they represent a novel class of chelators, which are worthy of further development as BFCs for (89)Zr.

Synthetic investigation of binary-ternary Cr(III)-hydroxycarboxylic acid-aromatic chelator systems. Structure-specific influence on adipogenic biomarkers linked to insulin mimesis.

PubMed

Tsave, O; Gabriel, C; Kafantari, M; Yavropoulou, M; Yovos, J G; Raptopoulou, C P; Psycharis, V; Terzis, A; Mateescu, C; Salifoglou, A

2018-07-01

In an attempt to understand the aqueous interactions of Cr(III) with low-molecular mass physiological ligands and examine its role as an adipogenic metallodrug agent in Diabetes mellitus II, the pH-specific synthesis in the binary-ternary Cr(III)-(HA = hydroxycarboxylic acid)-(N,N)-aromatic chelator (AC) (HA = 2-hydroxyethyl iminodiacetic acid/heidaH 2 , quinic acid; AC = 1,10-phenanthroline/phen) systems was pursued, leading to four new crystalline compounds. All materials were characterized by elemental analysis, UV-Visible, FT-IR, and ESI-MS spectroscopy, cyclic voltammetry, and X-Ray crystallography. Concurrently, the aqueous speciation of the binary Cr(III)-(2-hydroxyethyl iminodiacetic acid) system, complemented by ESI-MS, provided key-details of the species in solution correlating with the solid-state species. The structurally distinct Cr(III) soluble species were subsequently used in an in vitro investigation of their cytotoxic activity in 3T3-L1 fibroblast cultures. Compound 1 exhibited solubility, bioavailability, and atoxicity over a wide concentration range (0.1-100 μΜ) in contrast to 3, which was toxic. The adipogenic potential of 1 was subsequently investigated toward transformation of pre-adipocytes into mature adipocytes. Confirmation of that capacity relied on molecular biological techniques a) involving genes (glucose transporter type 4, peroxisome proliferator-activated receptor gamma, glucokinase, and adiponectin) serving as sensors of the transformation process, b) comparing the Cr(III)-adipogenicity potential to that of insulin, and c) exemplifying the ultimate maturity of adipocytes poised to catabolize glucose. The collective effort points out salient structural features in the coordination sphere of Cr(III) inducing adipogenic transformation relevant to combating hyperglycemia. The multiply targeted mechanistic insight into such a process exemplifies the role of well-defined Cr(III) complex forms as potential insulin

Optical fiber-based biosensors.

PubMed

Monk, David J; Walt, David R

2004-08-01

This review outlines optical fiber-based biosensor research from January 2001 through September 2003 and was written to complement the previous review in this journal by Marazuela and Moreno-Bondi. Optical fiber-based biosensors combine the use of a biological recognition element with an optical fiber or optical fiber bundle. They are classified by the nature of the biological recognition element used for sensing: enzyme, antibody/antigen (immunoassay), nucleic acid, whole cell, and biomimetic, and may be used for a variety of analytes ranging from metals and chemicals to physiological materials.

Understanding longitudinal wood fiber ultra-structure for producing cellulose nanofibrils using disk milling with diluted acid prehydrolysis

Treesearch

Yanlin Qin; Xueqing Qiu; Junyong Zhu

2016-01-01

Here we used dilute oxalic acid to pretreat a kraft bleached Eucalyptus pulp (BEP) fibers to facilitate mechanical fibrillation in producing cellulose nanofibrils using disk milling with substantial mechanical energy savings. We successfully applied a reaction kinetics based combined hydrolysis factor (CHFx) as a severity factor to quantitatively...

Effect of fiber sources on fatty acids profile, glycemic index, and phenolic compound content of in vitro digested fortified wheat bread.

PubMed

Kurek, Marcin Andrzej; Wyrwisz, Jarosław; Karp, Sabina; Wierzbicka, Agnieszka

2018-05-01

In this study, some dietary fiber (DF) sources were investigated as fortifiers of wheat bread: oat (OB), flax (FB), and apple (AB). Adding oat and flax fibers to bread significantly changed the fatty acid profiles. OB was highest in oleic acid (33.83% of lipids) and linoleic acid (24.31% of lipids). Only in FB, γ-linolenic fatty acid was present in a significant amount-18.32%. The bioaccessibility trails revealed that the DF slow down the intake of saturated fatty acids. PUFA were least bioaccessible from all fatty acids groups in the range of (72% in OB to 87% in FB). The control bread had the greatest value (80.5) and was significantly higher than values for OB, FB, and AB in terms of glycemic index. OB, FB and AB addition led to obtain low glycemic index. AB had a significant highest value of total phenolic (897.2 mg/kg) with the lowest values in FB (541.2 mg/kg). The only significant lowering of caloric values in this study was observed in AB. The study could address the gap in the area of research about taking into consideration glycemic index, fatty acid profile and phenolic content in parallel in terms of DF application in breads.

Inhibition of presynaptic activity by zinc released from mossy fiber terminals during tetanic stimulation.

PubMed

Minami, Akira; Sakurada, Naomi; Fuke, Sayuri; Kikuchi, Kazuya; Nagano, Tetsuo; Oku, Naoto; Takeda, Atsushi

2006-01-01

Zinc exists in high densities in the giant boutons of hippocampal mossy fibers. On the basis of the evidence that zinc decreases extracellular glutamate concentration in the hippocampus, the presynaptic action of zinc released from mossy fibers during high-frequency (tetanic) stimulation was examined using hippocampal slices. The increase in zinc-specific fluorescent signals was observed in both extracellular and intracellular compartments in the mossy fiber terminals during the delivery of tetanic stimuli (100 Hz, 1 sec) to the dentate granule cell layer, suggesting that zinc released from mossy fibers is immediately retaken up by mossy fibers. When mossy fiber terminals were preferentially double-stained with zinc and calcium indicators and tetanic stimuli (100 Hz, 1 sec) were delivered to the dentate granule cell layer, the increase in calcium orange signal during the stimulation was enhanced in mossy fiber terminals by addition of CaEDTA, a membrane-impermeable zinc chelator, and was suppressed by addition of zinc. The decrease in FM4-64 signal (vesicular exocytosis) during tetanic stimulation (10 Hz, 180 sec), which induced mossy fiber long-term potentiation, was also enhanced in mossy fiber terminals by addition of CaEDTA and was suppressed by addition of zinc. The present study demonstrates that zinc released from mossy fibers may be a negative-feedback factor against presynaptic activity during tetanic stimulation.

Evaluation of the efficacy of perorally administered glutamic acid-chelated iron and iron-dextran injected subcutaneously in Duroc and Norwegian Landrace piglets.

PubMed

Egeli, A K; Framstad, T

1998-02-01

The goals of this study were to evaluate the effect of orally administered amino acid-chelated iron (Fe) compared to injected Fe-dextran on haematology and weight gain in two different breeds raised under commercial conditions. Altogether 92 Duroc (D) pigs and 84 Norwegian Landrace (L) pigs from two different herds were included in the study. The day after birth the litters were divided in two groups (split litters). Group (Gr.) 1 was given 4 ml of a 50% solution of Super Fe-MAX (52 mg glutamic acid-chelated Fe in a water solution) orally, while Gr. 2 was subcutaneously (s.c.) injected with Idofer (180 mg Fe as ferridextran). Until weaning at 5 weeks, all the piglets had free access to a 3% solution of Super Fe-MAX (0.78 mg Fe/ml), access to pelleted food being given from 1 week of age. The piglets were weighed and bled before treatment the day after birth (day 1) and on days 4, 7, 14, 21 and 35. All piglets were weighed on days 28 and 49, while 72 of the L pigs were also weighed on days 77, 98 and 119. At weaning D pigs in Gr. 1 and Gr. 2 had a mean body weight of 8.64 kg and 8.30 kg, respectively, the corresponding figures for the L pigs being 10.82 kg and 10.34 kg. As regards the 72 L pigs followed to day 119, the mean weight in Gr. 1 and Gr. 2 was 80.6 kg and 80.2 kg, respectively. A significantly lower weight gain in the piglets with a birth weight below 1.2 kg in Gr. 2 compared with Gr. 1 indicated that excess administration of Fe to small piglets may have a detrimental effect on weight gain. From day 7 (D pigs) and on days 14 and 21 (L pigs), Gr. 2 had a significantly higher haemoglobin concentration (Hb) than Gr. 1. Nevertheless, Hb levels were also adequate in Gr. 1 in both breeds. There was a negative correlation between changes in Hb during the first weeks and the initial value. Though haematological values seemed to show inter-breed differences, with higher average erythrocyte counts (RBC) and Hb and lower mean cell volume (MCV) in the D pigs, the

Controlled core removal from a D-shaped optical fiber.

PubMed

Markos, Douglas J; Ipson, Benjamin L; Smith, Kevin H; Schultz, Stephen M; Selfridge, Richard H; Monte, Thomas D; Dyott, Richard B; Miller, Gregory

2003-12-20

The partial removal of a section of the core from a continuous D-shaped optical fiber is presented. In the core removal process, selective chemical etching is used with hydrofluoric (HF) acid. A 25% HF acid solution removes the cladding material above the core, and a 5% HF acid solution removes the core. A red laser with a wavelength of 670 nm is transmitted through the optical fiber during the etching. The power transmitted through the optical fiber is correlated to the etch depth by scanning electron microscope imaging. The developed process provides a repeatable method to produce an optical fiber with a specific etch depth.

Poly-3-hydroxy butyric acid interaction with the transgenic flax fibers: FT-IR and Raman spectra of the composite extracted from a GM flax

NASA Astrophysics Data System (ADS)

Wróbel-Kwiatkowska, Magdalena; Żuk, Magdalena; Szopa, Jan; Dymińska, Lucyna; Mączka, Mirosław; Hanuza, Jerzy

2009-07-01

The FT-IR and FT-Raman studies have been performed on commercial 3-hydroxy-butyric acid, commercial poly-3-hydroxy butyric acid as well as poly-3-hydroxy butyric acid (PHB) produced by bacteria. The data were compared to those obtained for poly-3-hydroxy butyric acid extracted from natural and genetically modified flax. Genetically modified flax was generated by expression of three bacterial genes coding for synthesis of poly-3-hydroxy butyric acid. Thus transgenic flaxes were enhanced with different amount of the PHB. The discussion of polymer structure and vibrational properties has been done in order to get insight into differences among these materials. The interaction between the cellulose of flax fibers and embedded poly-3-hydroxybutyric acid has been also discussed. The spectroscopic data provide evidences for structural changes in cellulose and in PHB when synthesized in fibers. Based on this data it is suggesting that cellulose and PHB interact by hydrogen and ester bonds.

Characterization of commercial iron chelates and their behavior in an alkaline and calcareous soil.

PubMed

Cantera, Rodrigo G; Zamarreño, Angel M; García-Mina, José M

2002-12-18

Iron deficiency is a common problem for many plants grown in alkaline and calcareous soils. To correct this problem, iron is supplied to plants as chelates. Several iron chelates are sold under diverse trademarks with different characteristics. This work evaluated 18 commercial products containing the most representative chelated iron sources used in agricultural practice in Spain when the study was done, namely the ferric chelates of EDDHA, EDDHMA, EDDCHA, EDDHSA, EDTA, and DTPA. The chelates were comprehensively characterized and quantitated by several techniques, including several chromatographic methods. Iron and chelate dynamics in soil were also studied in a model alkaline and calcareous soil. Results indicate that, in this model soil, among the different iron compounds studied only FeEDDHA and analogues have the capacity to maintain soluble iron in soil solution over time. These results are in agreement with general experience under field conditions. Furthermore, among the different ortho-ortho isomers of FeEDDHA's, FeEDDHSA and FeEDDCHA showed greater capacity than FeEDDHA and FeEDDHMA to maintain the chelated iron in soil solution over time.

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

PubMed

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

2014-08-01

Medical practitioners have treated atherosclerotic disease with chelation therapy for over 50 years. Lack of strong of evidence led conventional practitioners to abandon its use in the 1960s and 1970s. This relegated chelation therapy to complementary and alternative medicine practitioners, who reported good anecdotal results. Concurrently, the epidemiologic evidence linking xenobiotic metals with cardiovascular disease and mortality gradually accumulated, suggesting a plausible role for chelation therapy. On the basis of the continued use of chelation therapy without an evidence base, the National Institutes of Health released a Request for Applications for a definitive trial of chelation therapy. The Trial to Assess Chelation Therapy (TACT) was formulated as a 2 × 2 factorial randomized controlled trial of intravenous EDTA-based chelation vs. placebo and high-dose oral multivitamins and multiminerals vs. oral placebo. The composite primary endpoint was death, reinfarction, stroke, coronary revascularization, or hospitalization for angina. A total of 1708 post-MI patients who were 50 years or older with a creatinine of 2.0 or less were enrolled and received 55,222 infusions of disodium EDTA or placebo with a median follow-up of 55 months. Patients were on evidence-based post-MI medications including statins. EDTA proved to be safe. EDTA chelation therapy reduced cardiovascular events by 18%, with a 5-year number needed to treat (NNT) of 18. Prespecified subgroup analysis revealed a robust benefit in patients with diabetes mellitus with a 41% reduction in the primary endpoint (5-year NNT = 6.5), and a 43% 5-year relative risk reduction in all-cause mortality (5-year NNT = 12). The magnitude of benefit is such that it suggests urgency in replication and implementation, which could, due to the excellent safety record, occur simultaneously. Copyright © 2014 Elsevier Inc. All rights reserved.

Determining resin/fiber content of laminates

NASA Technical Reports Server (NTRS)

Garrard, G. G.; Houston, D. W.

1979-01-01

Article discusses procedure where hydrazine is used to extract graphite fibers from cured polyimide resin. Method does not attack graphite fibers and is faster than hot-concentrated-acid digestion process.

Chelation therapy to treat atherosclerosis, particularly in diabetes: is it time to reconsider?

PubMed

Lamas, Gervasio A; Ergui, Ian

2016-08-01

Case reports and case series have suggested a possible beneficial effect of chelation therapy in patients with atherosclerotic disease. Small randomized trials conducted in patients with angina or peripheral artery disease, however, were not sufficiently powered to provide conclusive evidence on clinical outcomes. The Trial to Assess Chelation Therapy (TACT) was the first randomized trial adequately powered to detect the effects of chelation therapy on clinical endpoints. We discuss results and future research. Expert commentary: Chelation reduced adverse cardiovascular events in a post myocardial infarction (MI) population. Patients with diabetes demonstrated even greater benefit, with a number needed to treat of 6.5 patients to prevent a cardiac event over 5 years, with a 41% relative reduction in risk of a cardiac event (p = 0.0002). These results led to the revision of the ACC/AHA guideline recommendations for chelation therapy, changing its classification from class III to class IIb. TACT2, a replicative trial, will assess the effects of chelation therapy on cardiovascular outcomes in diabetic patients with a prior myocardial infarction. We are seeking participating sites for TACT2.

Particulate nanocomposite from oyster (Crassostrea rivularis) hydrolysates via zinc chelation improves zinc solubility and peptide activity.

PubMed

Zhang, Ziran; Zhou, Feibai; Liu, Xiaoling; Zhao, Mouming

2018-08-30

An oyster protein hydrolysates-zinc complex (OPH-Zn) was prepared and investigated to improve zinc bioaccessibility. Zinc ions chelating with oyster protein hydrolysates (OPH) cause intramolecular and intermolecular folding and aggregation, homogeneously forming the OPH-Zn complex as nanoclusters with a Z-average at 89.28 nm (PDI: 0.16 ± 0.02). The primary sites of zinc-binding in OPH were carboxyl groups, carbonyl groups, and amino groups, and they were related to the high number of charged amino acid residues. Furthermore, formation of the OPH-Zn complex could significantly enhance zinc solubility both under specific pH conditions as well as during simulated gastrointestinal digestion, compared to the commonly used ZnSO 4 . Additionally, after digestion, either preserved or enhanced antioxidant activity of OPH was found when chelated with zinc. These results indicated that the OPH-Zn complex could be a potential functional ingredient with improved antioxidant bioactivity and zinc bioaccessibility. Copyright © 2018. Published by Elsevier Ltd.

Extraction of cellulose nano-crystals from old corrugated container fiber using phosphoric acid and enzymatic hydrolysis followed by sonication.

PubMed

Tang, Yanjun; Shen, Xiaochuang; Zhang, Junhua; Guo, Daliang; Kong, Fangong; Zhang, Nan

2015-07-10

Due to its amazing physicochemical properties and high environmental compatibility, cellulose nano-crystals (CNC) hold great promise for serving as a strategic platform for sustainable development. Now, there has been growing interest in the development of processes using waste or residual biomass as CNC source for addressing economic and environmental concerns. In the present work, a combined process involving phosphoric acid hydrolysis, enzymatic hydrolysis and sonication was proposed aiming to efficiently exact CNC from low-cost old corrugated container (OCC) pulp fiber. The effect of enzymatic hydrolysis on the yield and microstructure of resulting CNC was highlighted. Results showed that the enzymatic hydrolysis was effective in enhancing CNC yield after phosphoric acid hydrolysis. CNC was obtained with a yield of 23.98 wt% via the combined process with phosphoric acid concentration of 60 wt%, cellulase dosage of 2 mL (84 EGU) per 2g fiber and sonication intensity of 200 W. Moreover, the presence of enzymatic hydrolysis imparted the obtained CNC with improved dispersion, increased crystallinity and thermal stability. Copyright © 2015 Elsevier Ltd. All rights reserved.

Comparative techno-economic analysis of steam explosion, dilute sulfuric acid, ammonia fiber explosion and biological pretreatments of corn stover.

PubMed

Baral, Nawa Raj; Shah, Ajay

2017-05-01

Pretreatment is required to destroy recalcitrant structure of lignocelluloses and then transform into fermentable sugars. This study assessed techno-economics of steam explosion, dilute sulfuric acid, ammonia fiber explosion and biological pretreatments, and identified bottlenecks and operational targets for process improvement. Techno-economic models of these pretreatment processes for a cellulosic biorefinery of 113.5 million liters butanol per year excluding fermentation and wastewater treatment sections were developed using a modelling software-SuperPro Designer. Experimental data of the selected pretreatment processes based on corn stover were gathered from recent publications, and used for this analysis. Estimated sugar production costs ($/kg) via steam explosion, dilute sulfuric acid, ammonia fiber explosion and biological methods were 0.43, 0.42, 0.65 and 1.41, respectively. The results suggest steam explosion and sulfuric acid pretreatment methods might be good alternatives at present state of technology and other pretreatment methods require research and development efforts to be competitive with these pretreatment methods. Copyright © 2017 Elsevier Ltd. All rights reserved.

The liver glucose-6-phosphatase of intact microsomes is inhibited and displays sigmoid kinetics in the presence of alpha-ketoglutarate-magnesium and oxaloacetate-magnesium chelates.

PubMed

Mithieux, G; Vega, F V; Riou, J P

1990-11-25

We have recently shown that the Ca.EGTA and Mg.EDTA complexes, but not free Ca2+ or Mg2+, inhibit the liver glucose-6-phosphatase (Mithieux, G., Vega, F. V., Beylot, M., and Riou, J. P. (1990) J. Biol. Chem. 265, 7257-7259). In this work, we report that, when complexed with Mg2+, two endogenous dicarboxylic keto acids (alpha-ketoglutarate (alpha-KG) and oxaloacetate (OAA] inhibit the glucose-6-phosphatase activity at low concentrations of substrate. This phenomenon is specific for complexes of Mg2+ with alpha-KG and OAA since 1) the complexes of Mg2+ with a number of other di- or tricarboxylic acids having high structural analogy with alpha-KG and OAA (oxalate, malate, succinate, citrate, aspartate, and glutamate) do not inhibit the glucose-6-phosphatase activity and 2) the Ca.alpha-KG and Ca.OAA chelates do not inhibit the glucose-6-phosphatase activity. In the presence of Mg.alpha-KG or Mg.OAA chelates, the enzyme displays sigmoid kinetics; the Hanes plots deviate from linearity, indicating the positive cooperative dependence of the velocity upon the substrate concentration. Hill coefficients (equal to 1 in the absence of the chelates) of 1.23 and 1.33 have been determined in the presence of Mg.alpha-KG and Mg.OAA complexes, respectively. The disruption of microsomal integrity by detergents abolishes the effect of Mg.alpha-KG and Mg.OAA, suggesting that the magnesium chelates inhibit the translocase component of the glucose-6-phosphatase system.

Graphene Oxide and Gadolinium-Chelate Functionalized Poly(lactic acid) Nanocapsules Encapsulating Perfluorooctylbromide for Ultrasound/Magnetic Resonance Bimodal Imaging Guided Photothermal Ablation of Cancer.

PubMed

Li, Zhenglin; Ke, Hengte; Wang, Jinrui; Miao, Zhaohua; Yue, Xiuli

2016-03-01

This paper successfully fabricated a novel multifunctional theranostic agent (PFOB@PLA/GO/Gd-DTPA NCs) by loading perfluorooctylbromide (PFOB) into poly(lactic acid) (PLA) nanocapsules (NCs) followed by surface functionalization with graphene oxide (GO) and gadolinium-chelate (Gd-DTPA). It was found that the resulting nanoagent could serve as a contrast agent simultaneously to enhance ultrasound (US) and magnetic resonance imaging (MRI). Benefiting from the strong absorption in the near infrared (NIR) region, the nanocapsules could efficiently kill cancer cells under NIR laser irradiation. Thus, such a single theranostic agent with the combination of realtime US imaging and high-resolution MR imaging could achieve great therapeutic effectiveness without systemic damage to the body. In addition, the cytotoxicity assay on HUVEC cells revealed a good biocompatibility of PFOB@PLA/GO/Gd-DTPA NCs, showing that the versatile nanocapsule system may hold great potential as an effective nanoplatform for contrast enhanced imaging guided photothermal therapy.

SEPARATION OF PLUTONIUM FROM LANTHANUM BY CHELATION-EXTRACTION

DOEpatents

James, R.A.; Thompson, S.G.

1958-12-01

Plutonium can be separated from a mixture of plutonlum and lanthanum in which the lanthanum to plutonium molal ratio ls at least five by adding the ammonium salt of N-nitrosoarylhydroxylamine to an aqueous solution having a pH between about 3 and 0.2 and containing the plutonium in a valence state of at least +3, to form a plutonium chelate compound of N-nitrosoarylhydroxylamine. The plutonium chelate compound may be recovered from the solution by extracting with an immiscible organic solvent such as chloroform.

Hypolipidemic effect of hemicellulose component of coconut fiber.

PubMed

Sindhurani, J A; Rajamohan, T

1998-08-01

The neutral detergent fiber (NDF) isolated from coconut kernel was digested with cellulase and hemicellulase and the residual fiber rich in hemicellulose (without cellulose) and cellulose (with out hemicellulose) were fed to rats and compared with a fiber free group. The results indicate that hemicellulose rich fiber showed decreased concentration of total cholesterol, LDL + VLDL cholesterol and increased HDL cholesterol, while cellulose rich fiber showed no significant alteration. There was increased HMG CoA reductase activity and increased incorporation of labeled acetate into free cholesterol. Rats fed hemicellulose rich coconut fiber produced lower concentration of triglycerides and phospholipids and lower release of lipoproteins into circulation. There was increased concentration of hepatic bile acids and increased excretion of faecal sterols and bile acids. These results indicate that the hemicellulose component of coconut fiber was responsible for the observed hypolipidemic effect.

Effect of an oral starter dose of iron on haematology and weight gain in piglets having voluntary access to glutamic acid-chelated iron solution.

PubMed

Egeli, A K; Framstad, T

1998-01-01

Six litters of Norwegian Landrace piglets were included in the study. The day after birth (day 1), half of the piglets (split litters) were given 52 mg glutamic acid-chelated Fe (4 ml of a 50% solution of Super Fe-MAX) perorally. All the piglets had free access to a 3% solution of Super Fe-MAX from this day until weaning at 5 weeks. The piglets were weighed and blood samples collected on days 1, 4, 7, 14, 21 and 35, and weighed only on days 28 and 49. The production of erythrocytes and haemoglobin was greater in the first week after birth in piglets given extra iron perorally on day 1, compared to those with voluntary access to iron. The extra peroral iron administration did not prevent some of the piglets from becoming anaemic later. Weight gain was similar in the 2 groups.

Calcium Silicate/Chitosan-Coated Electrospun Poly (Lactic Acid) Fibers for Bone Tissue Engineering.

PubMed

Su, Chu-Jung; Tu, Ming-Gene; Wei, Li-Ju; Hsu, Tuan-Ti; Kao, Chia-Tze; Chen, Tsui-Han; Huang, Tsui-Hsien

2017-05-05

Electrospinning technology allows fabrication of nano- or microfibrous fibers with inorganic and organic matrix and it is widely applied in bone tissue engineering as it allows precise control over the shapes and structures of the fibers. Natural bone has an ordered composition of organic fibers with dispersion of inorganic apatite among them. In this study, poly (lactic acid) (PLA) mats were fabricated with electrospinning and coated with chitosan (CH)/calcium silicate (CS) mixer. The microstructure, chemical component, and contact angle of CS/CH-PLA composites were analyzed by scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. In vitro, various CS/CH-coated PLA mats increased the formation of hydroxyapatite on the specimens' surface when soaked in cell cultured medium. During culture, several biological characteristics of the human mesenchymal stem cells (hMSCs) cultured on CS/CH-PLA groups were promoted as compared to those on pure PLA mat. Increased secretion levels of Collagen I and fibronectin were observed in calcium silicate-powder content. Furthermore, with comparison to PLA mats without CS/CH, CS10 and CS15 mats markedly enhanced the proliferation of hMSCs and their osteogenesis properties, which was characterized by osteogenic-related gene expression. These results clearly demonstrated that the biodegradable and electroactive CS/CH-PLA composite mats are an ideal and suitable candidate for bone tissue engineering.

Clioquinol-zinc chelate: a candidate causative agent of subacute myelo-optic neuropathy.

PubMed Central

Arbiser, J. L.; Kraeft, S. K.; van Leeuwen, R.; Hurwitz, S. J.; Selig, M.; Dickersin, G. R.; Flint, A.; Byers, H. R.; Chen, L. B.

1998-01-01

BACKGROUND: 5-chloro-7-iodo-8-hydroxyquinoline (clioquinol) was used clinically three decades ago as an oral antiparasitic agent and to increase intestinal absorption of zinc in patients with acrodermatitis enteropathica, a genetic disorder of zinc absorption. Use of clioquinol was epidemiologically linked to subacute myelo-optic neuropathy (SMON), characterized by peripheral neuropathy and blindness, which affected 10,000 patients in Japan. Discontinuation of oral clioquinol use led to elimination of SMON, however, the mechanism of how clioquinol induces neurotoxicity is unclear. MATERIALS AND METHODS: We tested the effect of clioquinol-metal chelates on neural crest-derived melanoma cells. The effect of clioquinol chelates on cells was further studied by electron microscopy and by a mitochondrial potential-sensitive fluorescent dye. RESULTS: Of the ions tested, only clioquinol-zinc chelate demonstrated cytotoxicity. The cytotoxicity of clioquinol-zinc chelate was extremely rapid, suggesting that its primary effect was on the mitochondria. Electron microscopic analysis demonstrated that clioquinol-zinc chelate caused mitochondrial damage. This finding was further confirmed by the observation that clioquinol-zinc chelate caused a decrease in mitochondrial membrane potential. CONCLUSIONS: We demonstrate that clioquinol, in the presence of zinc, is converted to a potent mitochondrial toxin. The phenomenon of clioquinol mediated toxicity appears to be specific to zinc and is not seen with other metals tested. Since clioquinol has been shown to cause increased systemic absorption of zinc in humans, it is likely that clioquinol-zinc chelate was present in appreciable levels in patients with SMON and may be the ultimate causative toxin of SMON. Images Fig. 2 Fig. 3 PMID:9848083

Optical fiber-based sensors: application to chemical biology.

PubMed

Brogan, Kathryn L; Walt, David R

2005-10-01

Optical fibers have been used to develop sensors based on nucleic acids and cells. Sensors employing DNA probes have been developed for various genomics applications and microbial pathogen detection. Live cell-based sensors have enabled the monitoring of environmental toxins, and have been used for fundamental studies on populations of individual cells. Both single-core optical fiber sensors and optical fiber sensor arrays have been used for sensing based on nucleic acids and live cells.

Skeletal Muscle-Specific Overexpression of PGC-1α Induces Fiber-Type Conversion through Enhanced Mitochondrial Respiration and Fatty Acid Oxidation in Mice and Pigs.

PubMed

Zhang, Lin; Zhou, Ying; Wu, Wangjun; Hou, Liming; Chen, Hongxing; Zuo, Bo; Xiong, Yuanzhu; Yang, Jinzeng

2017-01-01

Individual skeletal muscles in the animal body are heterogeneous, as each is comprised of different fiber types. Type I muscle fibers are rich with mitochondria, and have high oxidative metabolisms while type IIB fibers have few mitochondria and high glycolytic metabolic capacity. Peroxisome proliferator-activated receptor gamma coactivator 1α (PGC-1α), a transcriptional co-activator that regulates mitochondrial biogenesis and respiratory function, is implicated in muscle fiber-type switching. Over-expression of PGC-1α in transgenic mice increased the proportion of red/oxidative type I fiber. During pig muscle growth, an increased number of type I fibers can give meat more red color. To explore the roles of PGC-1α in regulation of muscle fiber type conversion, we generated skeletal muscle-specific PGC-1α transgenic mice and pig. Ectopic over-expression of PGC-1α was detected in both fast and slow muscle fibers. The transgenic animals displayed a remarkable amount of red/oxidative muscle fibers in major skeletal muscle tissues. Skeletal muscles from transgenic mice and pigs have increased expression levels of oxidative fiber markers such as MHC1, MHC2x, myoglobin and Tnni1, and decreased expressions of glycolytic fiber genes (MHC2a, MHC2b, CASQ-1 and Tnni2). The genes responsible for the TCA cycle and oxidative phosphorylation, cytochrome coxidase 2 and 4, and citrate synthase were also increased in the transgenic mice and pigs. These results suggested that transgenic over-expressed PGC-1α significantly increased muscle mitochondrial biogenesis, resulting in qualitative changes from glycolytic to oxidative energy generation. The transgenic animals also had elevated levels of PDK4 and PPARγ proteins in muscle tissue, which can lead to increased glycogen deposition and fatty acid oxidation. Therefore, the results support a significant role of PGC-1α in conversion of fast glycolytic fibers to slow and oxidative fiber through enhanced mitochondrial respiration

Chelate-Modified Fenton Reaction for the Degradation of Trichloroethylene in Aqueous and Two-Phase Systems

PubMed Central

Lewis, Scott; Lynch, Andrew; Bachas, Leonidas; Hampson, Steve; Ormsbee, Lindell; Bhattacharyya, Dibakar

2009-01-01

Abstract The primary objective of this research was to model and understand the chelate-modified Fenton reaction for the destruction of trichloroethylene (TCE) present in both the aqueous and organic (in the form of droplets) phases. The addition of a nontoxic chelate (L), such as citrate or gluconic acid, allows for operation at near-neutral pH and controlled release of Fe(II)/Fe(III). For the standard Fenton reaction at low pH in two-phase systems, an optimum H2O2:Fe(II) molar ratio was found to be between 1:1 and 2:1. Experimentation proved the chelate-modified Fenton reaction effectively dechlorinated TCE in both the aqueous and organic phases at pH 6–7 using low H2O2:Fe(II) molar ratios (4:1 to 8:1). Increasing the L:Fe ratio was found to decrease the rate of H2O2 degradation in both Fe(II) and Fe(III) systems at near-neutral pH. Generalized models were developed to predict the concentration of TCE in the aqueous phase and TCE droplet radius as a function of time using literature-reported hydroxyl radical reaction kinetics and mass transfer relationships. Additional aspects of this work include the reusability of the Fe–citrate complex under repeated H2O2 injections in real water systems as well as packed column studies for simulated groundwater injection. PMID:20418966

Evaluation of macrocyclic hydroxyisophthalamide ligands as chelators for zirconium-89

PubMed Central

Xu, Jide; Tatum, David; Magda, Darren

2017-01-01

The development of bifunctional chelators (BFCs) for zirconium-89 immuno-PET applications is an area of active research. Herein we report the synthesis and evaluation of octadentate hydroxyisophthalamide ligands (1 and 2) as zirconium-89 chelators. While both radiometal complexes could be prepared quantitatively and with excellent specific activity, preparation of 89Zr-1 required elevated temperature and an increased reaction time. 89Zr-1 was more stable than 89Zr-2 when challenged in vitro by excess DTPA or serum proteins and in vivo during acute biodistribution studies. Differences in radiometal complex stability arise from structural changes between the two ligand systems, and suggest further ligand optimization is necessary to enhance 89Zr chelation. PMID:28575044

Evaluation of macrocyclic hydroxyisophthalamide ligands as chelators for zirconium-89.

PubMed

Bhatt, Nikunj B; Pandya, Darpan N; Xu, Jide; Tatum, David; Magda, Darren; Wadas, Thaddeus J

2017-01-01

The development of bifunctional chelators (BFCs) for zirconium-89 immuno-PET applications is an area of active research. Herein we report the synthesis and evaluation of octadentate hydroxyisophthalamide ligands (1 and 2) as zirconium-89 chelators. While both radiometal complexes could be prepared quantitatively and with excellent specific activity, preparation of 89Zr-1 required elevated temperature and an increased reaction time. 89Zr-1 was more stable than 89Zr-2 when challenged in vitro by excess DTPA or serum proteins and in vivo during acute biodistribution studies. Differences in radiometal complex stability arise from structural changes between the two ligand systems, and suggest further ligand optimization is necessary to enhance 89Zr chelation.

Deferasirox, an oral iron chelator, prevents hepatocarcinogenesis and adverse effects of sorafenib.

PubMed

Yamamoto, Naoki; Yamasaki, Takahiro; Takami, Taro; Uchida, Koichi; Fujisawa, Koichi; Matsumoto, Toshihiko; Saeki, Issei; Terai, Shuji; Sakaida, Isao

2016-05-01

Although sorafenib is expected to have a chemopreventive effect on hepatocellular carcinoma (HCC) recurrence, there are limitations to its use because of adverse effects, including effects on liver function. We have reported that the iron chelator, deferoxamine can prevent liver fibrosis and preneoplastic lesions. We investigated the influence of administering a new oral iron chelator, deferasirox (DFX), on the effects of sorafenib. We used the choline-deficient l-amino acid-defined (CDAA) diet-induced rat liver fibrosis and HCC model. We divided rats into four groups: CDAA diet only (control group), CDAA diet with sorafenib (sorafenib group), CDAA diet with DFX (DFX group), and CDAA diet with DFX and sorafenib (DFX + sorafenib group). Liver fibrosis and development of preneoplastic lesions were assessed. In addition, we assessed adverse effects such as changes in body and liver weight, skin damage (eruption, dryness, and hair loss), which is defined as hand-foot skin syndrome, in the sorafenib and DFX + sorafenib groups. The combination of DFX + sorafenib markedly prevented liver fibrosis and preneoplastic lesions better than the other treatments. Furthermore, the combination therapy significantly decreased adverse effects compared with the sorafenib group. In conclusion, the combination therapy with DFX and sorafenib may be a useful adjuvant therapy to prevent recurrence after curative treatment of HCC.

Effect of pH and aging time on the kinetic dissociation of 243Am(III) from humic acid-coated gamma-Al2O3: a chelating resin exchange study.

PubMed

Wang, Xiangke; Chen, Changlun; Du, Jinzhou; Tan, Xiaoli; Di, Xu; Yu, Shaoming

2005-09-15

The chelating resin was studied to assess its influence on metal availability and mobility in the environment. The association of organic-inorganic colloid-borne trace elements was investigated in this work. The radionuclide 243Am(III) was chosen as the representative and chemical homologue for trivalent lanthanide and actinide ions present in radioactive nuclear waste. The kinetic dissociation behavior of 243Am(III) from humic acid-coated gamma-Al2O3 was studied at pH values of 4.0 +/- 0.1, 5.0 +/- 0.2, and 6.0 +/- 0.2 with a contact time of 2 days after the addition of a chelating cation exchanger resin. The concentrations of the components were: 243Am(III) 3.0 x 10(-7) mol/L, gamma-Al2O3 0.5 g/L, HA 10 mg/L (pH 4.0 +/- 0.1, 5.0 +/- 0.2, and 6.0 +/- 0.2) and 50 mg/L (pH 6.0 +/- 0.2), respectively. The kinetics of dissociation of 243Am(III) after different equilibration time with humic acid-coated gamma-Al2O3 was also investigated at pH 5.0 +/- 0.2. The experiments were carried out in air and at ambient temperature. The results suggest that the fraction of irreversible bonding of radionuclides to HA-coated Al2O3 increases with increasing pH and is independent of aging time. The assumption of two different 243Am(III)-HA-Al2O3 species, with "fast" and "slow" dissociation kinetics, is required to explain the experimental results. 243Am(III) species present on HA-Al2O3 colloids moves from the "fast" to the "slow" dissociating sites with the increase of aging time.

Metal-chelating polymers by anionic ring-opening polymerization and their use in quantitative mass cytometry.

PubMed

Illy, Nicolas; Majonis, Daniel; Herrera, Isaac; Ornatsky, Olga; Winnik, Mitchell A

2012-08-13

Metal-chelating polymers (MCPs) are important reagents for multiplexed immunoassays based on mass cytometry. The role of the polymer is to carry multiple copies of individual metal isotopes, typically as lanthanide ions, and to provide a reactive functionality for convenient attachment to a monoclonal antibody (mAb). For this application, the optimum combination of chain length, backbone structure, end group, pendant groups, and synthesis strategy has yet to be determined. Here we describe the synthesis of a new type of MCP based on anionic ring-opening polymerization of an activated cyclopropane (the diallyl ester of 1,1-cyclopropane dicarboxylic acid) using a combination of 2-furanmethanethiol and a phosphazene base as the initiator. This reaction takes place with rigorous control over molecular weight, yielding a polymer with a narrow molecular weight distribution, reactive pendant groups for introducing a metal chelator, and a functional end group with orthogonal reactivity for attaching the polymer to the mAbs. Following the ring-opening polymerization, a two-step transformation introduced diethylenetriaminepentaacetic acid (DTPA) chelating groups on each pendant group. The polymers were characterized by NMR, size exclusion chromatography (SEC), and thermogravimetric analysis (TGA). The binding properties toward Gd(3+) as a prototypical lanthanide (Ln) ion were also studied by isothermal titration calorimetry (ITC). Attachment to a mAb involves a Diels-Alder reaction of the terminal furan with a bismaleimide, followed by a Michael addition of a thiol on the mAb, generated by mild reduction of a disulfide bond in the hinge region. Polymer samples with a number average degree of polymerization of 35, with a binding capacity of 49.5 ± 6 Ln(3+) ions per chain, were loaded with 10 different types of Ln ions and conjugated to 10 different mAbs. A suite of metal-tagged Abs was tested by mass cytometry in a 10-plex single cell analysis of human adult peripheral blood

Long-term depression at the mossy fiber-deep cerebellar nucleus synapse.

PubMed

Zhang, Wei; Linden, David J

2006-06-28

Several lines of evidence have indicated that the deep cerebellar nuclei (DCN) are a site of memory storage for certain forms of motor learning, most notably associative eyelid conditioning. In particular, these experiments, together with network models, have implicated the excitatory glutamatergic synapse between mossy fibers and DCN neurons in this memory trace. However, to date, evidence for persistent use-dependent change in the strength of this synapse has been almost entirely absent. Here, we report that high-frequency burst stimulation of mossy fibers, either alone or paired with postsynaptic depolarization, gives rise to long-term depression (LTD) of the mossy fiber-DCN synapse. This form of LTD is not associated with changes in the paired-pulse ratio and is blocked by loading with a postsynaptic Ca2+ chelator but not by bath application of an NMDA receptor antagonist. Mossy fiber-DCN LTD requires activation of a group I metabotropic glutamate receptor (mGluR) and protein translation. Unlike mGluR/translation-dependent LTD in other brain regions, this form of LTD requires mGluR1 and is mGluR5 independent.

Assessment of a gel-type chelating preparation containing 1-hydroxyethylidene-1, 1-bisphosphonate.

PubMed

Girard, S; Paqué, F; Badertscher, M; Sener, B; Zehnder, M

2005-11-01

To test an aqueous gel containing 1-hydroxyethylidene-1, 1-bisphosphonate (HEBP) regarding its interactions with sodium hypochlorite, its calcium binding capacity, and its potential in preventing the formation of a smear layer when used in conjunction with rotary root canal preparation. The experimental aqueous gel consisted of (w/v) 2% alginate, 3% aerosil, 10% Tween 80 and 18% HEBP. Interactions of gel components with hypochlorite were assessed using iodometric titration and monochromatic ultraviolet spectrometry. Two commercial paste-type chelators containing ethylenediaminetetraacetic acid (EDTA) and peroxide (RC-Prep and Glyde) served as controls. Calcium-binding capacities were measured in mixtures with a Ca2+ standard solution buffered at pH 10 using a calcium-selective measuring chain. Finally, root canals of 16 extracted single-rooted premolars per group were instrumented using ProFile instruments dipped in the experimental gel, RC-Prep, or nothing. Additionally, canals were rinsed with 10 mL of a 1% NaOCl solution during/after preparation. Smear scores in instrumented teeth were monitored using scanning electron microscopy. None of the experimental gel components showed short-term interactions with hypochlorite, whilst EDTA, peroxide, RC-Prep and Glyde immediately reduced the hypochlorite in solution. The experimental gel chelated 30 mg Ca2+ g-1, compared with 16 mg Ca2+ g-1 and 11 mg Ca2+ g-1 chelated by RC-Prep and Glyde respectively. Smear scores obtained with the experimental gel were significantly (P<0.05) lower than with RC-Prep in coronal and middle root thirds, whilst no differences were observed in apical root thirds. Under the conditions of this study, an HEBP gel appeared advantageous over currently available products.

How does the nucleolar number involve in muscle fiber atrophy? Response to Beta-guanidinopropionic acid supplementation

NASA Astrophysics Data System (ADS)

Matsuoka, Yoshikazu; Kawano, Fuminori; Oke, Yoshihiko; Higo, Yoko; Umemoto, Shiori; Kawabe, Naoko; Wang, Xiaodong; Terada, Masahiro; Shinoda, Yo; Lan, Yongbo; Ogura, Akihiko; Ohira, Yoshinobu

2005-08-01

To investigate the relationship between the myonuclear capability and the number of nucleolus during muscle remodeling, oral supplementation of β-guanidinopropionic acid (β-GPA) on the characteristics of plantaris muscle fibers was performed for 2 weeks in adult male Wistar rats. Effects of β-GPA supply in culture medium on mouse myoblast cell line C2C12 was also studied. The mean fiber cross-sectional area was less in β-GPA-fed than control rats (35%, p<0.05). And the myonuclear number per mm of fiber length was significantly greater (35%, p<0.05). Thus, the cytoplasmic volume per myonucleus was less (52%) in β-GPA-fed rats (p<0.05). The number of nucleolar organizer regions (NORs) per myonucleus was also less (17%) in β-GPA-fed group (p<0.05). The number of NORs was greater (14%) in the myoblasts cultured with creatine phosphate compared with non-supplemented control, but it was less (10%) in the myoblasts cultured with β-GPA (p<0.05). Further, the number of NORs was also greater (26%) in the differentiated myotubes cultured with creatine phosphate (p<0.05). The results suggested that the nucleoli may play some role(s) in the regulation of muscle fiber size and its number may be influenced by creatine content.

Quantification of the fate of dietary fiber in humans by a newly developed radiolabeled fiber marker.

PubMed

Carryer, P W; Brown, M I; Malagelada, J R; Carlson, G L; McCall, J T

1982-06-01

A radiolabeled cellulose (131I-fiber) that retains the essential physical and chemical properties of this class of fiber was developed in our laboratory. We quantified the fate of orally ingested 131I-fiber in healthy individuals by external gamma camera monitoring and fecal collections. The marker passes virtually intact through the human gastrointestinal tract with negligible release and absorption of the label in the gut. Comparison of the gastric emptying rate of 131I-fiber with that of a predominantly aqueous marker, 99mTc-diethylenetriamine pentaacetic acid (99mTc-DTPA), showed that 131I-fiber strands were evacuated more slowly than intragastric fluids. An important finding was that some 131I-fiber emptying occurred during most time periods, even before liquids were completely evacuated. This suggests that the human stomach is able to empty simultaneously liquids and fiber strands (1-15 mm in length) that are resistant to grinding by antral mechanical forces and to digestion by acid-peptic secretion. Thus, some nondigestible solids may be emptied with the bulk of a meal, although at a slower rate. 131I-Fiber may be a useful marker for quantifying gastric emptying of nondigestible solids. Further, the stability of 131I-fiber in the gut, as opposed to most other physiologic solid labels, should enable future investigation of intestinal and colonic transit of fiber, which is an important component of the human diet.

Iron chelation as a possible mechanism for aspirin-induced malondialdehyde production by mouse liver microsomes and mitochondria.

PubMed Central

Schwarz, K B; Arey, B J; Tolman, K; Mahanty, S

1988-01-01

To investigate the possibility that lipid peroxidation is the mechanism responsible for aspirin-induced liver damage, pure neutralized acetylsalicylic acid (ASA), 0.6-90.9 mM, was added to calcium-aggregated mouse liver microsomes followed by incubation in NADPH buffer at 37 degrees C for 60 min and subsequent measurement of malondialdehyde (MDA). MDA production at ASA concentrations from 1.2 to 4.6 mM was greater than control (P less than 0.004). Peak MDA values were observed with 4.6 mM ASA, 39.58 +/- 6.73 nmol MDA/mg protein vs. 16.16 +/- 2.85 (P less than 0.004). Higher concentrations of ASA were inhibitory compared with the value at 4.6 mM (P less than 0.001). Aspirin had similar effects on MDA production by mouse liver mitochondria. MDA production with either ASA or buffer was completely suppressed by the potent iron-chelating agents desferrioxamine and alpha,alpha' dipyridyl when these were added to the microsomal preparations. Since MDA production in this system is known to be affected by iron-chelating agents (enhanced at low concentration, inhibited at higher concentration), the iron-chelating properties of ASA were investigated. Conductivity titration curves of Fe(OH)3 added to water or ASA suggested that the ASA was complexing with iron. The presence of an iron-ASA complex was established by high pressure liquid chromatographic analysis of the solution from this study. We conclude that aspirin enhances MDA production by hepatic microsomes and mitochondria via an aspirin-iron chelate and that this represents at least one mechanism by which aspirin may produce liver damage. PMID:3335633

Hydroxypyridinone Derivatives: A Fascinating Class of Chelators with Therapeutic Applications - An Update.

PubMed

Chaves, Sílvia; Piemontese, Luca; Hiremathad, Asha; Santos, Maria A

2018-01-01

Hydroxypyridinones (HPs) are a family of N-heterocyclic metal chelators, which have been an attractive target in the development of a variety of new pharmaceutical drugs, due to their high metal chelating efficacy/specificity and easy derivatization to tune the desired biological properties. In fact, along the last decades, hydroxypyridinone derivatives, but mostly 3-hydroxy-4-pyridinone (3,4-HP), have been intensively used in drug design, following either a multitarget approach, in which one chelating unity is extrafunctionalized (hybridized) to enable the interaction with other important specific biological sites, or a polydenticity approach, in which more than one chelating moiety is conveniently attached to one scaffold, to increase the metal chelating efficacy. This review represents an update of the most recent publications (2014-2016) in mono-HP hybrids, namely as potential anti-Alzheimer's drugs, inhibitors of metalloenzymes and anti-microbials, and also polychelating compounds (poly- HP), in view of potential application, such as anti-microbial/biostatic agents, luminescent biosensors or diagnostic agents. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Cage-like bifunctional chelators, copper-64 radiopharmaceuticals and PET imaging using the same

DOEpatents

Conti, Peter S.; Cai, Hancheng; Li, Zibo; Liu, Shuanglong

2016-08-02

Disclosed is a class of versatile Sarcophagine based bifunctional chelators (BFCs) containing a hexa-aza cage for labeling with metals having either imaging, therapeutic or contrast applications radiolabeling and one or more linkers (A) and (B). The compounds have the general formula ##STR00001## where A is a functional group selected from group consisting of an amine, a carboxylic acid, an ester, a carbonyl, a thiol, an azide and an alkene, and B is a functional group selected from the group consisting of hydrogen, an amine, a carboxylic acid, and ester, a carbonyl, a thiol, an azide and an alkene. Also disclosed are conjugate of the BFC and a targeting moiety, which may be a peptide or antibody. Also disclosed are metal complexes of the BFC/targeting moiety conjugates that are useful as radiopharmaceuticals, imaging agents or contrast agents.

No-core fiber-based highly sensitive optical fiber pH sensor.

PubMed

Bhardwaj, Vanita; Pathak, Akhilesh Kumar; Singh, Vinod Kumar

2017-05-01

The present work describes the fabrication and characterization of an optical fiber pH sensor using a sol–gel technique. The sensing head configuration is incorporated using a short section of no-core fiber, coated with tetraethyl orthosilicate and spliced at the end of a single mode fiber with a bulge. Different types of indicators (bromophenol blue, cresol red, and chlorophenol red) were used to achieve a wide pH range from 2 to 13. High sensitivities of the fabricated device were found to be 1.02 and ? 0.93 ?? nm / pH for acidic and alkaline solutions, respectively. From the characterization results, it was noted that there is an impact of ionic strength and an effect of the temperature of liquid on the response characteristic, which is an advantage of the existing device over the other pH sensors. The fabricated sensor exhibited good reflection spectrum, indicating a blueshift in resonance wavelength for alkaline solutions and a redshift for acidic solutions.

Experimental Investigation on the Mechanism of Chelation-Assisted, Copper(II) Acetate-Accelerated Azide-Alkyne Cycloaddition

PubMed Central

Kuang, Gui-Chao; Guha, Pampa M.; Brotherton, Wendy S.; Simmons, J. Tyler; Stankee, Lisa A.; Nguyen, Brian T.; Clark, Ronald J.; Zhu, Lei

2011-01-01

A mechanistic model is formulated to account for the high reactivity of chelating azides (organic azides capable of chelation-assisted metal coordination at the alkylated azido nitrogen position) and copper(II) acetate (Cu(OAc)2) in copper(II)-mediated azide-alkyne cycloaddition (AAC) reactions. Fluorescence and 1H NMR assays are developed for monitoring the reaction progress in two different solvents – methanol and acetonitrile. Solvent kinetic isotopic effect and pre-mixing experiments give credence to the proposed different induction reactions for converting copper(II) to catalytic copper(I) species in methanol (methanol oxidation) and acetonitrile (alkyne oxidative homocoupling), respectively. The kinetic orders of individual components in a chelation-assisted, copper(II)-accelerated AAC reaction are determined in both methanol and acetonitrile. Key conclusions resulting from the kinetic studies include (1) the interaction between copper ion (either in +1 or +2 oxidation state) and a chelating azide occurs in a fast, pre-equilibrium step prior to the formation of the in-cycle copper(I)-acetylide, (2) alkyne deprotonation is involved in several kinetically significant steps, and (3) consistent with prior experimental and computational results by other groups, two copper centers are involved in the catalysis. The X-ray crystal structures of chelating azides with Cu(OAc)2 suggest a mechanistic synergy between alkyne oxidative homocoupling and copper(II)-accelerated AAC reactions, in which both a bimetallic catalytic pathway and a base are involved. The different roles of the two copper centers (a Lewis acid to enhance the electrophilicity of the azido group and a two-electron reducing agent in oxidative metallacycle formation, respectively) in the proposed catalytic cycle suggest that a mixed valency (+2 and +1) dinuclear copper species be a highly efficient catalyst. This proposition is supported by the higher activity of the partially reduced Cu(OAc)2 in

HPTLC Fingerprinting and Cholinesterase Inhibitory and Metal-Chelating Capacity of Various Citrus Cultivars and
Olea europaea

PubMed Central

Senol, Fatma Sezer; Ankli, Anita; Reich, Eike

2016-01-01

Summary Inhibitory activity of thirty-one ethanol extracts obtained from albedo, flavedo, seed and leaf parts of 17 cultivars of Citrus species from Turkey, the bark and leaves of Olea europaea L. from two locations (Turkey and Cyprus) as well as caffeic acid and hesperidin was tested against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), related to the pathogenesis of Alzheimer’s disease, using ELISA microtiter assays at 500 µg/mL. Metal-chelating capacity of the extracts was also determined. BChE inhibitory effect of the Citrus sp. extracts was from (7.7±0.7) to (70.3±1.1) %, whereas they did not show any inhibition against AChE. Cholinesterase inhibitory activity of the leaf and bark ethanol extracts of O. europaea was very weak ((10.2±3.1) to (15.0±2.3) %). The extracts had either no or low metal-chelating capacity at 500 µg/mL. HPTLC fingerprinting of the extracts, which indicated a similar phytochemical pattern, was also done using the standards of caffeic acid and hesperidin with weak cholinesterase inhibition. Among the screened extracts, the albedo extract of C. limon ‘Interdonato’, the flavedo extracts of ‘Kara Limon’ and ‘Cyprus’ cultivars and the seed extract of C. maxima appear to be promising as natural BChE inhibitors. PMID:27956858

Enhanced in vitro activity of tigecycline in the presence of chelating agents.

PubMed

Deitchman, Amelia N; Singh, Ravi Shankar Prasad; Rand, Kenneth H; Derendorf, Hartmut

2018-05-01

The lack of availability of novel antibiotic agents and the rise of resistance to existing therapies has led clinicians to utilise combination therapy to adequately treat bacterial infections. Here we examined how chelators may impact the in vitro activity of tigecycline (TIG) against Pseudomonas aeruginosa, Escherichia coli and Klebsiella pneumoniae. Minimum inhibitory concentrations (MICs) were determined by broth dilution with and without various combinations of chelators (EDTA and other tetracyclines) and metal ions (i.e. calcium, magnesium). Trimethoprim (TMP) was used as a non-chelating control. Addition of metal ions led to increases in MICs, whilst addition of EDTA led to decreases in MICs. The chelating effects of EDTA were reversed by addition of magnesium and most profoundly calcium. Similar effects of EDTA and calcium were observed for tetracycline (TET) and TMP. When other tetracyclines (TET, oxytetracycline (OXY) and chlortetracycline (CHL)) were used as chelators at concentrations below their MICs, TIG MICs decreased for P. aeruginosa but not for E. coli. Some decreases in TIG MICs were observed for K. pneumoniae when TET and CHL were added. A dose-dependent decrease in TIG MIC was observed for TET and was reversed by the addition of calcium. The presence of effects of EDTA and calcium on TMP MICs indicates that mechanisms outside of TIG chelation likely play a role in enhanced activity. Full characterisation of an unexpected interaction such as TIG-TET with different microorganisms could provide valuable insights into the underlying mechanisms and design of physiologically viable chelators as candidates for future combinations regimens. Copyright © 2018 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.

An improved TCF sequence for biobleaching kenaf pulp: influence of the hexenuronic acid content and the use of xylanase.

PubMed

Andreu, Glòria; Vidal, Teresa

2014-01-01

Enzymatic delignification with laccase from Trametes villosa used in combination with chemical mediators (acetosyringone, acetovanillone and 1-hydroxybenzotriazole) to improve the totally chlorine-free (TCF) bleaching of kenaf pulp was studied. The best final pulp properties were obtained by using an LHBTQPo sequence developed by incorporating a laccase-mediator stage into an industrial bleaching sequence involving chelation and peroxide stages. The new sequence resulted in increased kenaf pulp delignification (90.4%) and brightness (77.2%ISO) relative to a conventional TCF chemical sequence (74.5% delignification and 74.5% brightness). Also, the sequence provided bleached kenaf fibers with high cellulose content (pulp viscosity of 890 g·mL(-1) vs 660 g·mL(-1)). Scanning electron micrographs revealed that xylanase altered fiber surfaces and facilitated reagent access as a result. However, the LHBTX (xylanase) stage removed 21% of hexenuronic acids in kenaf pulp. These recalcitrant compounds spent additional bleaching reagents and affected pulp properties after peroxide stage. Copyright © 2013 Elsevier Ltd. All rights reserved.

Effect of fiber diameter and orientation on fibroblast morphology and proliferation on electrospun poly(D,L-lactic-co-glycolic acid) meshes.

PubMed

Bashur, Chris A; Dahlgren, Linda A; Goldstein, Aaron S

2006-11-01

Engineered ligament tissues are promising materials for the repair of tears and ruptures, but require the development of biomaterial scaffolds that not only support physiologically relevant loads, but also possess architectures capable of orienting cell adhesion and extracellular matrix deposition. Based on evidence that micron-scale topographic features induce cell orientation through a contact guidance phenomenon, we postulate that oriented micron-scale fiber meshes-formed by the electrospinning process-can regulate cell morphology. To test this, fused fiber meshes of poly(d,l-lactic-co-glycolic acid) (PLGA) were electrospun onto rigid supports under conditions that produced mean fiber diameters of 0.14-3.6 microm, and angular standard deviations of 31-60 degrees . Analysis of the morphology of adherent NIH 3T3 fibroblasts indicated that projected cell area and aspect ratio increased systematically with both increasing fiber diameter and degree of fiber orientation. Importantly, cell morphology on 3.6 microm fibers was similar to that on spincoated PLGA films. Finally, cell densities on electrospun meshes were not significantly different from spincoated PLGA, indicating that cell proliferation is not sensitive to fiber diameter or orientation.

Optical high acidity sensor

DOEpatents

Jorgensen, Betty S.; Nekimken, Howard L.; Carey, W. Patrick; O'Rourke, Patrick E.

1997-01-01

An apparatus and method for determining acid concentrations in solutions having acid concentrations of from about 0.1 Molar to about 16 Molar is disclosed. The apparatus includes a chamber for interrogation of the sample solution, a fiber optic light source for passing light transversely through the chamber, a fiber optic collector for receiving the collimated light after transmission through the chamber, a coating of an acid resistant polymeric composition upon at least one fiber end or lens, the polymeric composition in contact with the sample solution within the chamber and having a detectable response to acid concentrations within the range of from about 0.1 Molar to about 16 Molar, a measurer for the response of the polymeric composition in contact with the sample solution, and, a comparer of the measured response to predetermined standards whereby the acid molarity of the sample solution within the chamber can be determined. Preferably, a first lens is attached to the end of the fiber optic light source, the first lens adapted to collimate light from the fiber optic light source, and a second lens is attached to the end of the fiber optic collector for focusing the collimated light after transmission through the chamber.

Optical high acidity sensor

DOEpatents

Jorgensen, B.S.; Nekimken, H.L.; Carey, W.P.; O`Rourke, P.E.

1997-07-22

An apparatus and method for determining acid concentrations in solutions having acid concentrations of from about 0.1 Molar to about 16 Molar is disclosed. The apparatus includes a chamber for interrogation of the sample solution, a fiber optic light source for passing light transversely through the chamber, a fiber optic collector for receiving the collimated light after transmission through the chamber, a coating of an acid resistant polymeric composition upon at least one fiber end or lens, the polymeric composition in contact with the sample solution within the chamber and having a detectable response to acid concentrations within the range of from about 0.1 Molar to about 16 Molar, a measurer for the response of the polymeric composition in contact with the sample solution, and a comparer of the measured response to predetermined standards whereby the acid molarity of the sample solution within the chamber can be determined. Preferably, a first lens is attached to the end of the fiber optic light source, the first lens adapted to collimate light from the fiber optic light source, and a second lens is attached to the end of the fiber optic collector for focusing the collimated light after transmission through the chamber. 10 figs.

Evaluation of macrocyclic hydroxyisophthalamide ligands as chelators for zirconium-89

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bhatt, Nikunj B.; Pandya, Darpan N.; Xu, Jide

The development of bifunctional chelators (BFCs) for zirconium-89 immuno-PET applications is an area of active research. We report the synthesis and evaluation of octadentate hydroxyisophthalamide ligands (1 and 2) as zirconium-89 chelators. And while both radiometal complexes could be prepared quantitatively and with excellent specific activity, preparation of 89Zr-1 required elevated temperature and an increased reaction time. 89Zr-1 was more stable than 89Zr-2 when challenged in vitro by excess DTPA or serum proteins and in vivo during acute biodistribution studies. The differences in radiometal complex stability arise from structural changes between the two ligand systems, and suggest further ligand optimizationmore » is necessary to enhance 89Zr chelation.« less

Evaluation of macrocyclic hydroxyisophthalamide ligands as chelators for zirconium-89

DOE PAGES

Bhatt, Nikunj B.; Pandya, Darpan N.; Xu, Jide; ...

2017-06-02

The development of bifunctional chelators (BFCs) for zirconium-89 immuno-PET applications is an area of active research. We report the synthesis and evaluation of octadentate hydroxyisophthalamide ligands (1 and 2) as zirconium-89 chelators. And while both radiometal complexes could be prepared quantitatively and with excellent specific activity, preparation of 89Zr-1 required elevated temperature and an increased reaction time. 89Zr-1 was more stable than 89Zr-2 when challenged in vitro by excess DTPA or serum proteins and in vivo during acute biodistribution studies. The differences in radiometal complex stability arise from structural changes between the two ligand systems, and suggest further ligand optimizationmore » is necessary to enhance 89Zr chelation.« less

Cereal fiber, fruit fiber, and type 2 diabetes: Explaining the paradox.

PubMed

Davison, Karen M; Temple, Norman J

2018-02-01

While the relationship between dietary fiber and type 2 diabetes mellitus (T2DM) has been much studied, the evidence about its role in the prevention and control of this condition has been conflicting. We critically evaluate prospective cohort studies and randomized controlled trials (RCTs) that examined insoluble/nonviscous/cereal fiber and soluble/viscous/fruit fiber in relation to risk of T2DM. Taken as a whole this evidence indicates that, in the quantities typically eaten, cereal fiber is protective against T2DM while fruit fiber gives little protection. We argue that the protective action of cereal fiber may be explained by the modulating effects of gut microbiota through mechanisms such as: 1) improving glucose tolerance via energy metabolism pathways (colonic fermentation and generation of short-chain fatty acids); 2) reducing inflammation; and 3) altering the immune response. By gaining more knowledge of specific host and gut microbial functional pathways involved in T2DM development and the potential role of cereal fiber, appropriate disease prevention and intervention strategies may be developed. Copyright © 2017 Elsevier Inc. All rights reserved.

Inhibitory Activity of Iron Chelators ATA and DFO on MCF-7 Breast Cancer Cells and Phosphatases PTP1B and SHP2.

PubMed

Kuban-Jankowska, Alicja; Sahu, Kamlesh K; Gorska-Ponikowska, Magdalena; Tuszynski, Jack A; Wozniak, Michal

2017-09-01

Rapidly-dividing cancer cells have higher requirement for iron compared to non-transformed cells, making iron chelating a potential anticancer strategy. In the present study we compared the anticancer activity of uncommon iron chelator aurintricarboxylic acid (ATA) with the known deferoxamine (DFO). We investigated the impact of ATA and DFO on the viability and proliferation of MCF-7 cancer cells. Moreover we performed enzymatic activity assays and computational analysis of the ATA and DFO effects on pro-oncogenic phosphatases PTP1B and SHP2. ATA and DFO decrease the viability and proliferation of breast cancer cells, but only ATA considerably reduces the activity of PTP1B and SHP2 phosphatases. Our studies indicated that ATA strongly inactivates and binds in the PTP1B and SHP2 active site, interacting with arginine residue essential for enzyme activity. We confirmed that iron chelating can be considered as a potential strategy for the adjunctive treatment of breast cancer. Copyright© 2017, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.

Labeling Biomolecules with Radiorhenium - a Review of the Bifunctional Chelators

PubMed Central

Liu, Guozheng; Hnatowich, Donald J.

2007-01-01

For radiotherapy, biomolecules such as intact antibodies, antibody fragments, peptides, DNAs and other oligomers have all been labeled with radiorhenium (186Re and 188Re). Three different approaches have been employed that may be referred to as direct, indirect and integral labeling. Direct labeling applies to proteins and involves the initial reduction of endogenous disulfide bridges to provide chelation sites. Indirect labeling can apply to most biomolecules and involves the initial attachment of an exogenous chelator. Finally, integral labeling is a special case applying only to small molecules in which the metallic radionuclide serves to link two parts of a biomolecule together in forming the labeled complex. While the number of varieties for the direct and integral radiolabeling approaches is rather limited, a fairly large and diverse number of chelators have been reported in the case of indirect labeling. Our objective herein is to provide an overview of the various chelators that have been used in the indirect labeling of biomolecules with radiorhenium, including details on the labeling procedures, the stability of the radiolabel and, where possible, the influence of the label on biological properties. PMID:17504162

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

DOEpatents

Srivastava, Suresh C.; Meinken, George E.

2001-01-01

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

Hydroxypyridonate and hydroxypyrimidinone chelating agents

DOEpatents

Raymond, Kenneth N.; Doble, Daniel M.; Sunderland, Christopher J.; Thompson, Marlon

2005-01-25

The present invention provides hydroxypyridinone and hydroxypyrimidone chelating agents. Also provides are Gd(III) complexes of these agents, which are useful as contrast enhancing agents for magnetic resonance imaging. The invention also provides methods of preparing the compounds of the invention, as well as methods of using the compounds in magnetic resonance imaging applications.

Acid hydrolysis of cellulose to yield glucose

DOEpatents

Tsao, George T.; Ladisch, Michael R.; Bose, Arindam

1979-01-01

A process to yield glucose from cellulose through acid hydrolysis. Cellulose is recovered from cellulosic materials, preferably by pretreating the cellulosic materials by dissolving the cellulosic materials in Cadoxen or a chelating metal caustic swelling solvent and then precipitating the cellulose therefrom. Hydrolysis is accomplished using an acid, preferably dilute sulfuric acid, and the glucose is yielded substantially without side products. Lignin may be removed either before or after hydrolysis.

Immobilization of heavy metals on pillared montmorillonite with a grafted chelate ligand.

PubMed

Brown, Loren; Seaton, Kenneth; Mohseni, Ray; Vasiliev, Aleksey

2013-10-15

The objective of this work was the development of an efficient adsorbent for irreversible immobilization of heavy metals in contaminated soils. The adsorbent was prepared by pillaring of montmorillonite with silica followed by grafting of a chelate ligand on its surface. Obtained adsorbent was mesoporous with high content of adsorption sites. Its structure was studied by BET adsorption of N2, dynamic light scattering, and scanning electron microscopy. The adsorption capacity of the organoclay was measured by its mixing with contaminated kaolin and soil samples and by analysis of heavy metal contents in leachate. Deionized water and 50% acetic acid were used for leaching of metals from the samples. As it was demonstrated by the experiments, the adsorbent was efficient in immobilization of heavy metals not only in neutral aqueous media but also in the presence of weak acid. As a result, the adsorbent can be used for reduction of heavy metal leaching from contaminated sites. Copyright © 2013 Elsevier B.V. All rights reserved.

Photocatalysts Based on Cobalt-Chelating Conjugated Polymers for Hydrogen Evolution from Water

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Lianwei; Hadt, Ryan G.; Yao, Shiyu

Developing photocatalytic systems for water splitting to generate oxygen and hydrogen is one of the biggest chemical challenges in solar energy utilization. In this work, we report the first example of heterogeneous photocatalysts for hydrogen evolution based on in-chain cobalt-chelating conjugated polymers. Four conjugated polymers chelated with earth abundant cobalt ions were synthesized and found to evolve hydrogen photocatalytically from water. These polymers are designed to combine functions of the conjugated backbone as light-harvesting antenna and electron transfer conduit with the in-chain bipyridyl chelated transition metal centers as catalytic active sites. In addition, these polymers are soluble in organic solvents,more » enabling effective interactions with the substrates as well as detailed characterization. We also found a polymer-dependent optimal cobalt chelating concentration at which the highest photocatalytic hydrogen production (PHP) activity can be achieved.« less

Labeling of monoclonal antibodies with a 67Ga-phenolic aminocarboxylic acid chelate. Part II. Comparison of immunoreactivity and biodistribution of monoclonal antibodies labeled with the 67Ga-chelate or with 131I.

PubMed

Matzku, S; Schuhmacher, J; Kirchgessner, H; Brüggen, J

1986-01-01

Coupling of the 67Ga-P-EDDHA chelate via carbodiimide to the anti-melanoma monoclonal antibody (Mab) M.2.9.4 resulted in a low degree of oligomerization, but a considerable degree of intra-molecular (inter-chain) cross-linking. However, this did not impair immunoreactivity, nor did the half-life in vivo differ substantially from that of 131I-M.2.9.4. Biodistribution analysis in normal mice showed Ga:I ratios near 1 in the blood and other tissues not involved in degradation and label excretion. In tissues of the reticulo-endothelial system (RES) and the kidneys, Ga:I ratios up to 2.51 were reached within 4 days of administration. In antigen-positive MeWo tumor tissue, retention of 67Ga also excreted that of 131I, so that tumor; organ ratios (except tumor:liver) were superior for the 67Ga-labeled MAb. It is concluded that the method of coupling pre-established 67Ga-P-EDDHA chelate to antibody results in a functionally intact tracer molecule, whose persistence in vivo is not significantly impaired. The major difference to I-labeled MAbs may be a prolonged retention of Ga in tissues (cells) physiologically involved in antibody catabolism.

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

PubMed

Marsella, Maria; Borgna-Pignatti, Caterina

2014-08-01

Iron overload is an inevitable consequence of blood transfusions and is often accompanied by increased iron absorption from the gut. Chelation therapy is necessary to prevent the consequences of hemosiderosis. Three chelators, deferoxamine, deferiprone, and deferasirox, are presently available and a fourth is undergoing clinical trials. The efficacy of all 3 available chelators has been demonstrated. Also, many studies have shown the efficacy of the combination of deferoxamine plus deferiprone as an intensive treatment of severe iron overload. Alternating chelators can reduce adverse effects and improve compliance. Adherence to therapy is crucial for good results. Copyright © 2014 Elsevier Inc. All rights reserved.

A Novel Nuclease Activity that is Activated by Ca2+ Chelated to EGTA

PubMed Central

Dominguez, Kenneth; Ward, W. Steven

2010-01-01

Most nucleases require a divalent cation as a cofactor, usually Mg2+ or Ca2+, and are inhibited by the chelators EDTA and EGTA. We report the existence of a novel nuclease activity, initially identified in the luminal fluids of the mouse male reproductive tract but subsequently found in other tissues, that requires EGTA chelated to calcium to digest DNA. We refer to this unique enzyme as CEAN (Chelated EGTA Activated Nuclease). Using a fraction of vas deferens luminal fluid, plasmid DNA was degraded in the presence of excess Ca2+ (Ca2+:EGTA = 16) or excess EGTA (Ca2+:EGTA = 0.25), but required the presence of both. Higher levels of EGTA (Ca2+:EGTA = 0.10) prevented activity, suggesting that unchelated EGTA may be a competitive inhibitor. The EGTA-Ca2+ activation of CEAN is reversible as removing EGTA-Ca2+ stops ongoing DNA degradation, but adding EGTA-Ca2+ again reactivates the enzyme. This suggests the possibility that CEAN binds directly to EGTA-Ca2+. CEAN has a greater specificity for the chelator than for the divalent cation. Two other chelators, BAPTA and sodium citrate, do not activate CEAN in the presence of cation, but chelated EDTA does. EGTA chelated to other divalent cations such as Mn2+, Zn2+, and Cu2+ activate CEAN, but not Mg2+. The activity is lost upon boiling suggesting that it is a protein. These data suggest that EGTA and EDTA may not always prevent DNA from nuclease damage. PMID:19938954

Iron Chelation Nanoparticles with Delayed Saturation as an Effective Therapy for Parkinson Disease.

PubMed

Wang, Nan; Jin, Xin; Guo, Dongbo; Tong, Gangsheng; Zhu, Xinyuan

2017-02-13

Iron accumulation in substantia nigra pars compacta (SNpc) has been proved to be a prominent pathophysiological feature of Parkinson's diseases (PD), which can induce the death of dopaminergic (DA) neurons, up-regulation of reactive oxygen species (ROS), and further loss of motor control. In recent years, iron chelation therapy has been demonstrated to be an effective treatment for PD, which has shown significant improvements in clinical trials. However, the current iron chelators are suboptimal due to their short circulation time, side effects, and lack of proper protection from chelation with ions in blood circulation. In this work, we designed and constructed iron chelation therapeutic nanoparticles protected by a zwitterionic poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) to delay the saturation of iron chelators in blood circulation and prolong the in vivo lifetime, with HIV-1 trans-activating transcriptor (TAT) served as a shuttle to enhance the blood-brain barrier (BBB) permeability. We explored and investigated whether the Parkinsonian neurodegeneration and the corresponding symptoms in behaviors and physiologies could be prevented or reversed both in vitro and in vivo. The results demonstrated that iron chelator loaded therapeutic nanoparticles could reverse functional deficits in Parkinsonian mice not only physiologically but also behaviorally. On the contrary, both untreated PD mice and non-TAT anchored nanoparticle treated PD mice showed similar loss in DA neurons and difficulties in behaviors. Therefore, with protection of zwitterionic polymer and prolonged in vivo lifetime, iron chelator loaded nanoparticles with delayed saturation provide a PD phenotype reversion therapy and significantly improve the living quality of the Parkinsonian mice.

Separation of silver nanoparticles by hollow fiber flow field-flow fractionation: Addition of tannic acid into carrier liquid as a modifier.

PubMed

Saenmuangchin, Rattaporn; Mettakoonpitak, Jaruwan; Shiowatana, Juwadee; Siripinyanond, Atitaya

2015-10-09

A homemade hollow fiber flow-field fractionation (Hf-FlFFF) coupled with inductively coupled plasma mass spectrometry (ICP-MS) was set-up for silver nanoparticles (AgNPs) separation by using polysulfone hollow fiber membrane (30,000 MW cutoff) as a separation channel. Tannic acid and citrate stabilized AgNPs were synthesized and introduced into Hf-FlFFF. The effects of carrier liquid and stabilizing agent on retention behavior of AgNPs were investigated. Different elution behaviors were observed as follows: with 0.02% (w/v) FL-70, all of AgNPs were eluted from Hf-FlFFF but differences in retention behaviors were observed for AgNPs with tannic acid and citrate stabilizing agents; and with 30mM TRIS buffer, only tannic acid stabilized AgNPs were eluted from Hf-FlFFF, whereas citrate stabilized AgNPs were not eluted. In this work, tannic acid addition into carrier liquid was proposed to modify the surface of AgNPs and the surface of the membrane, and thereby adjusting the retention behaviors of AgNPs. Various concentrations of tannic acid were added into FL-70 and TRIS buffer. With the use of 0.1mM tannic acid in 30mM TRIS buffer as the carrier liquid, retention behaviors of both tannic acid stabilized- and citrate stabilized-AgNPs were similar and with similar fractionation recovery. Copyright © 2015 Elsevier B.V. All rights reserved.