N-acetylcysteine protects rats with chronic renal failure from gadolinium-chelate nephrotoxicity.

Directory of Open Access Journals (Sweden)

Leonardo Victor Barbosa Pereira

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

Hydroxyurea could be a good clinically relevant iron chelator.

Science.gov (United States)

Italia, Khushnooma; Colah, Roshan; Ghosh, Kanjaksha

2013-01-01

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

Hydroxyurea could be a good clinically relevant iron chelator.

Directory of Open Access Journals (Sweden)

Khushnooma Italia

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

Characterization of antibody-chelator conjugates: Determination of chelator content by terbium fluorescence titration

Energy Technology Data Exchange (ETDEWEB)

Brandt, K.D.; Schnobrich, K.E.; Johnson, D.K. (Abbott Laboratories, Department 90M, Abbott Park, IL (United States))

1991-01-01

Fluorescence titrations were performed by adding varying mole ratios of terbium(III) to antibody conjugates formed by benzyl isothiocyanate derivatives of three different polyaminopolycarboxylate chelators (NTA, EDTA, and DTPA) and the results compared to values for average chelator content obtained by cobalt-57 binding assays. For two different murine monoclonal antibodies, the average chelator content obtained by terbium fluorescence titration correlated closely with that measured by the cobalt-57 binding assay. It is concluded that lanthanide fluorescence titrations provide a useful alternative to radiometal binding assays for the determination of chelator content in protein-chelator conjugates.

Characterization of antibody-chelator conjugates: Determination of chelator content by terbium fluorescence titration

International Nuclear Information System (INIS)

Brandt, K.D.; Schnobrich, K.E.; Johnson, D.K.

1991-01-01

Fluorescence titrations were performed by adding varying mole ratios of terbium(III) to antibody conjugates formed by benzyl isothiocyanate derivatives of three different polyaminopolycarboxylate chelators (NTA, EDTA, and DTPA) and the results compared to values for average chelator content obtained by cobalt-57 binding assays. For two different murine monoclonal antibodies, the average chelator content obtained by terbium fluorescence titration correlated closely with that measured by the cobalt-57 binding assay. It is concluded that lanthanide fluorescence titrations provide a useful alternative to radiometal binding assays for the determination of chelator content in protein-chelator conjugates

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

Science.gov (United States)

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.

Chelating polymeric membranes

KAUST Repository

Peinemann, Klaus-Viktor; Villalobos Vazquez de la Parra, Luis Francisco; Hilke, Roland

2015-01-01

microporous chelating polymeric membrane. Embodiments include, but are not limited to, microporous chelating polymeric membranes, device comprising the membranes, and methods of using and making the same.

Chelation Therapy for Mercury Poisoning

Directory of Open Access Journals (Sweden)

Rong Guan

2009-01-01

Full Text Available Chelation therapy has been the major treatment for heavy metal poisoning. Various chelating agents have been developed and tested for treatment of heavy metal intoxications, including mercury poisoning. It has been clearly shown that chelating agents could rescue the toxicity caused by heavy metal intoxication, but the potential preventive role of chelating agents against heavy metal poisoning has not been explored much. Recent paper by Siddiqi and colleagues has suggested a protective role of chelating agents against mercury poisoning, which provides a promising research direction for broader application of chelation therapy in prevention and treatment of mercury poisoning.

Protracted chelate therapy after incorporation of plutonium 239 in rats

International Nuclear Information System (INIS)

Gemenetzis, E.

1976-01-01

The author has tested in how far 239 Pu can be mobilized by Ca and Zn, Desfenioxamin B(DFDA) and by combined doses of Ca-DTPA and DFDA. The pre-experiment covered the 239 Pu-metabolism in untreated male and female rats and the distribution in dependence of the way of application. If treatment is started immediately by multiple chelate doses, the first two injections play the main part in the decorporation of 239 Pu. The combination Ca-DTPA30 + DFDA30 μMol x kg -1 is proved to be the best means of decorporation for the whole body. The efficiency of another therapy depends essentially on the treatment used, a daily treatment showing the best effects. If treatment is started later with multiple chelate doses, the total decorporation efficiency is of less value, especially in the skeleton. Aequimolar doses of Ca-DTPA and Zn-DTPA have the same degree of efficiency. This indicates that during protracted chelate treatment starting later, Ca-DTPA could be substituted by the less toxic Zn-DTPA after incorporation of 239 Pu. These results show that intermittant administration of the week's dose is more efficient than a single chelate administration of the whole week's dose at once. Permanent chelate infusion does not seem necessary in any case since it has the same effect as 3 to 5 injections per week and is difficult to carry out in medical practice. Thus, it seems advisable to divide up the weekly dose into 3-5 injections. In case of a wound contamination, the efficiency of immediate intensive treatment depends on the 239 Pu compound used, on the chelate used, and on its dosage. (orig.) [de

The ATPG Attack for Reverse Engineering of Combinational Hybrid Custom-Programmable Circuits

Science.gov (United States)

2017-03-23

Introduction The widely practiced horizontal integrated circuit supply chain exposes a design to various types of attacks including the reverse engineering ...STT_CMOS designs for reverse- engineering prevention, DAC 2016. [5] M. E. Massad and et. al. Integrated circuit (IC) decamouflaging: reverse...The ATPG Attack for Reverse Engineering of Combinational Hybrid Custom-Programmable Circuits Raza Shafiq Hamid Mahmoodi Houman Homayoun Hassan

Chelation in metal intoxication

DEFF Research Database (Denmark)

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

2015-01-01

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

In vitro and in vivo evaluation of potential aluminum chelators.

Science.gov (United States)

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.

New thermo-sensitive chelating surfactants for selective solvent-free extraction of uranyl nitrate

International Nuclear Information System (INIS)

Prevost, S.; Larpent, C.; Testard, F.; Coulombeau, H.; Baczko, K.; Berthon, L.; Desvaux, H.; Madic, C.; Zemb, T.

2004-01-01

Functional surfactants were synthesised by grafting a chelating group (amino-acid residue) to the tip of a poly-ethoxylated nonionic surfactant chain (C i E j : C i H 2i +1(OCH 2 CH 2 ) j OH)) or in a branched position. C i E j nonionic surfactants are known to be thermo-reversible and to exhibit a clouding phenomenon associated to phase separation of micelles. The functional surfactants retain both surface-active properties, characteristic thermo-reversible behaviour and have efficient complexing properties toward uranyl. In the presence of uranyl nitrate, small micelles are formed at ambient temperature and the de-mixing leads to a separation of the target ion trapped by the functional surfactant (cloud point extraction). Those surfactants are more efficient than mixture of classical C i E j and complexing agent solubilized in the micelles. This reveals a synergistic effect of the covalent bond between the chelating group and the nonionic surfactant C i E j . This paper presents a systematic study of the extraction and aggregation properties and the influence of the nature of the ions. (authors)

Chelation Therapy for Mercury Poisoning

OpenAIRE

Rong Guan; Han Dai

2009-01-01

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

N- vs. C-Domain Selectivity of Catalytic Inactivation of Human Angiotensin Converting Enzyme by Lisinopril-Coupled Transition Metal Chelates

Science.gov (United States)

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

2014-01-01

The N- and C-terminal domains of human somatic Angiotensin I Converting Enzyme (sACE-1) demonstrate distinct physiological functions, with resulting interest in the development of domain-selective inhibitors for specific therapeutic applications. Herein, the activity of lisinopril-coupled transition metal chelates were tested for both reversible binding and irreversible catalytic inactivation of sACE-1. C/N domain binding selectivity ratios ranged from 1 to 350, while rates of irreversible catalytic inactivation of the N- and C-domains were found to be significantly greater for the N-domain, suggesting a more optimal orientation of the M-chelate-lisinopril complexes within the active site of the N-domain of sACE-1. Finally, the combined effect of binding selectivity and inactivation selectivity was assessed for each catalyst (double-filter selectivity factors), and several catalysts were found to cause domain-selective catalytic inactivation. The results of this study demonstrate the ability to optimize the target selectivity of catalytic metallopeptides through both binding and orientation factors (double-filter effect). PMID:24228790

N- versus C-domain selectivity of catalytic inactivation of human angiotensin converting enzyme by lisinopril-coupled transition metal chelates.

Science.gov (United States)

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

2013-12-27

The N- and C-terminal domains of human somatic angiotensin I converting enzyme (sACE-1) demonstrate distinct physiological functions, with resulting interest in the development of domain-selective inhibitors for specific therapeutic applications. Herein, the activity of lisinopril-coupled transition metal chelates was tested for both reversible binding and irreversible catalytic inactivation of each domain of sACE-1. C/N domain binding selectivity ratios ranged from 1 to 350, while rates of irreversible catalytic inactivation of the N- and C-domains were found to be significantly greater for the N-domain, suggesting a more optimal orientation of M-chelate-lisinopril complexes within the active site of the N-domain of sACE-1. Finally, the combined effect of binding selectivity and inactivation selectivity was assessed for each catalyst (double-filter selectivity factors), and several catalysts were found to cause domain-selective catalytic inactivation. The results of this study demonstrate the ability to optimize the target selectivity of catalytic metallopeptides through both binding and catalytic factors (double-filter effect).

CaNa2EDTA chelation attenuates cell damage in workers exposed to lead--a pilot study.

Science.gov (United States)

Čabarkapa, A; Borozan, S; Živković, L; Stojanović, S; Milanović-Čabarkapa, M; Bajić, V; Spremo-Potparević, B

2015-12-05

Lead induced oxidative cellular damage and long-term persistence of associated adverse effects increases risk of late-onset diseases. CaNa2EDTA chelation is known to remove contaminating metals and to reduce free radical production. The objective was to investigate the impact of chelation therapy on modulation of lead induced cellular damage, restoration of altered enzyme activities and lipid homeostasis in peripheral blood of workers exposed to lead, by comparing the selected biomarkers obtained prior and after five-day CaNa2EDTA chelation intervention. The group of smelting factory workers diagnosed with lead intoxication and current lead exposure 5.8 ± 1.2 years were administered five-day CaNa2EDTA chelation. Elevated baseline activity of antioxidant enzymes Cu, Zn-SOD and CAT as well as depleted thiols and increased protein degradation products-carbonyl groups and nitrites, pointing to Pb induced oxidative damage, were restored toward normal values following the treatment. Lead showed inhibitor potency on both RBC AChE and BChE in exposed workers, and chelation re-established the activity of BChE, while RBC AChE remained unaffected. Also, genotoxic effect of lead detected in peripheral blood lymphocytes was significantly decreased after therapy, exhibiting 18.9% DNA damage reduction. Administration of chelation reversed the depressed activity of serum PON 1 and significantly decreased lipid peroxidation detected by the post-chelation reduction of MDA levels. Lactate dehydrogenase LDH1-5 isoenzymes levels showed evident but no significant trend of restoring toward normal control values following chelation. CaNa2EDTA chelation ameliorates the alterations linked with Pb mediated oxidative stress, indicating possible benefits in reducing health risks associated with increased oxidative damage in lead exposed populations. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Olivine-type cathode for rechargeable batteries: Role of chelating agents

International Nuclear Information System (INIS)

Kandhasamy, Sathiyaraj; Singh, Pritam; Thurgate, Stephen; Ionescu, Mihail; Appadoo, Dominique; Minakshi, Manickam

2012-01-01

Highlights: ► Olivine powder was synthesized by sol–gel method using a range of chelating agents. ► Role of chelating agents in olivine cathode was investigated for battery application. ► Battery was fabricated with olivine cathode, Zn anode and aqueous electrolyte. ► Synergetic effect of additives (CA + TEA + PVP) led to improved storage capacity. - Abstract: Olivine (LiCo 1/3 Mn 1/3 Ni 1/3 PO 4 ) powders were synthesized at 550–600 °C for 6 h in air by a sol–gel method using multiple chelating agents and used as a cathode material for rechargeable batteries. Range of chelating agents like a weak organic acid (citric acid – CA), emulsifier (triethanolamine – TEA) and non-ionic surfactant (polyvinylpyrrolidone – PVP) in sol–gel wet chemical synthesis were used. The dependence of the physicochemical properties of the olivine powders such as particle size, morphology, structural bonding and crystallinity on the chelating agent was extensively investigated. Among the chelating agents used, unique cycling behavior (75 mAh/g after 25 cycles) is observed for the PVP assisted olivine. This is due to volumetric change in trapped organic layer for first few cycles. The trapped organic species in the electrode–electrolyte interface enhances the rate of lithium ion diffusion with better capacity retention. In contrast, CA and TEA showed a gradual capacity fade of 30 and 38 mAh/g respectively after multiple cycles. The combination of all the three mixed chelating agents showed an excellent electrochemical behavior of 100 mAh/g after multiple cycles and the synergistic effect of these agents are discussed.

Preparation of novel polyamine-type chelating resin with hyperbranched structures and its adsorption performance

Science.gov (United States)

Zhao, Wei; Wang, Huan; Li, Yuhong; Li, Chenxi

2018-01-01

This paper explored the method of combining atom transfer radical polymerization (ATRP) technology and hyperbranched polymer principle to prepare the high capacity chelating resin. First, surface-initiated atom transfer radical polymerization (SI-ATRP) method was used to graft glycidyl methacrylate (GMA) on chloromethylated cross-linked styrene-divinylbenzene resin, and then the novel polyamine chelating resin with a kind of hyperbranched structure was prepared through the amination reaction between amino group of (2-aminoethyl) triamine and epoxy group in GMA. This resin had a selective effect on As(V) and Cr(VI) at a relatively low pH and can be used for the disposal of waste water containing As(V) and Cr(VI). It had a relatively strong adsorption effect on Cu(II), Pb(II), Cd(II) and Cr(III) and can be used for the disposal of heavy metal ion waste water. The finding was that, the adsorption capacity of resin on the studied heavy metal ions was higher than that of the chelating resin synthesized by traditional technology and also higher than that of the resin modified by ATRP technology and bifunctional chelator, indicating that the combination of ATRP and hyperbranched polymer concept is an effective method to prepare chelating resin with high capacity. PMID:29515875

Preparation of novel polyamine-type chelating resin with hyperbranched structures and its adsorption performance

Science.gov (United States)

Chen, Youning; Zhao, Wei; Wang, Huan; Li, Yuhong; Li, Chenxi

2018-02-01

This paper explored the method of combining atom transfer radical polymerization (ATRP) technology and hyperbranched polymer principle to prepare the high capacity chelating resin. First, surface-initiated atom transfer radical polymerization (SI-ATRP) method was used to graft glycidyl methacrylate (GMA) on chloromethylated cross-linked styrene-divinylbenzene resin, and then the novel polyamine chelating resin with a kind of hyperbranched structure was prepared through the amination reaction between amino group of (2-aminoethyl) triamine and epoxy group in GMA. This resin had a selective effect on As(V) and Cr(VI) at a relatively low pH and can be used for the disposal of waste water containing As(V) and Cr(VI). It had a relatively strong adsorption effect on Cu(II), Pb(II), Cd(II) and Cr(III) and can be used for the disposal of heavy metal ion waste water. The finding was that, the adsorption capacity of resin on the studied heavy metal ions was higher than that of the chelating resin synthesized by traditional technology and also higher than that of the resin modified by ATRP technology and bifunctional chelator, indicating that the combination of ATRP and hyperbranched polymer concept is an effective method to prepare chelating resin with high capacity.

Combined treatment with lisofylline and exendin-4 reverses autoimmune diabetes

International Nuclear Information System (INIS)

Yang Zandong; Chen Meng; Carter, Jeffrey D.; Nunemaker, Craig S.; Garmey, James C.; Kimble, Sarah D.; Nadler, Jerry L.

2006-01-01

Type 1 diabetes mellitus (T1DM) is an autoimmune disease leading to near complete pancreatic β-cell destruction. New evidence suggests that β-cell regeneration is possible, but ongoing autoimmune damage prevents restoration of β-cell mass. We tested the hypothesis that simultaneously blocking autoimmune cytokine damage and supplying a growth-promoting stimulus for β-cells would provide a novel approach to reverse T1DM. Therefore, in this study we combined lisofylline to suppress autoimmunity and exendin-4 to enhance β-cell proliferation for treating autoimmune-mediated diabetes in the non-obese diabetic (NOD) mouse model. We found that this combined therapy effectively reversed new-onset diabetes within a week of therapy, and even maintained euglycemia up to 145 days after treatment withdrawal. The therapeutic effect of this regimen was associated with improved β-cell metabolism and insulin secretion, while reducing β-cell apoptosis. It is possible that such combined therapy could become a new strategy to defeat T1DM in humans

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

Science.gov (United States)

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.

Chelating polymeric membranes

KAUST Repository

Peinemann, Klaus-Viktor

2015-01-22

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

Article Commentary: Chelation Therapy for Mercury Poisoning

Directory of Open Access Journals (Sweden)

Rong Guan

2009-01-01

Full Text Available Chelation therapy has been the major treatment for heavy metal poisoning. Various chelating agents have been developed and tested for treatment of heavy metal intoxications, including mercury poisoning. It has been clearly shown that chelating agents could rescue the toxicity caused by heavy metal intoxication, but the potential preventive role of chelating agents against heavy metal poisoning has not been explored much. Recent paper by Siddiqi and colleagues has suggested a protective role of chelating agents against mercury poisoning, which provides a promising research direction for broader application of chelation therapy in prevention and treatment of mercury poisoning.

IRON CHELATION THERAPY IN THALASSEMIA SYNDROMES

Directory of Open Access Journals (Sweden)

Paolo Cianciulli

2009-06-01

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

Mixed ligand chelate therapy for plutonium and toxic metals from energy power production. Final report, April 15, 1977-October 14, 1980

International Nuclear Information System (INIS)

Schubert, J.

1980-01-01

The results of experiments are summarized on the ability of combinations of chelating agents to modify the genotoxicity or tissue distributions. The mutagenicities of Cr and of chelating agents were determined. The metals described in the report are Pu(IV), Cd(II), Cr(III), and Cr(VI). Accurate measurements were made of the ability of CaNa 2 EDTA, CaNa 3 DTPA, and DMPS to reduce mortality in mice given doses (i.p.) of CdCl 2 well above the 100% lethal level. The efficacy in terms of the mmoles/kg needed to reduce the mortality was: DTPA > EDTA > DMPS. The combination of DTPA + DMPS proved most promising though little evidence for mixed complex formation was noted. Potentiometric titration studies the case of Pu(IV) a few combinations proved effective, but only when given shortly after Pu administration and then only in the liver but not the skeleton. It is recommended that metabolically stable chelating agents be used in combinations, especially for those combinations which may form very stable mixed ligand chelates

Manganese(II) chelate contrast media

International Nuclear Information System (INIS)

Rocklage, S.M.; Quay, S.C.

1994-01-01

New chelate forming compounds for use as contrast media in NMR imaging are described. Especially mentioned are manganese(II) ion chelates of N,N' dipyridoxaldiamine, N,N' diacetic acid, and salts and esters thereof. 1 fig

Decomposition rates of radiopharmaceutical indium chelates in serum

International Nuclear Information System (INIS)

Yeh, S.M.; Meares, C.F.; Goodwin, D.A.

1979-01-01

The rates at which six small aminopolycarboxylate chelates of trivalent 111 In and three protein-bound chelates of 111 In deliver indium to the serum protein transferrin have been studied in sterile human serum at pH 7.3, 37 deg C. Sterically hindered chelates containing a substituent on an ethylene carbon of EDTA decompose with rates in the range 0.03 to 0.11% per day - one to two orders of magnitude slower than other chelates. Only small differences are observed between rates of decomposition for low-molecular-weight chelates and for protein-bound chelates having analogous structures. (author)

Effect of Ionic and Chelate Assisted Hexavalent Chromium on Mung Bean Seedlings (Vigna radiata L. wilczek. var k-851 During Seedling Growth

Directory of Open Access Journals (Sweden)

Mohanty, Monalisa

2013-04-01

Full Text Available The effect of Cr+6 with and without chelating agents were assessed in mung bean seedlings grown hydroponically. It was noted that the growth parameters showed a declining trend with increasing Cr+6 concentrations without chelate application. Among the seedlings grown with chelated chromium complexes, Cr+6–DTPA (10µM showed highest growth rate of roots as well as shoots. At higher concentration of Chromium i.e. Cr+6 (100µM, there exhibited high chlorophyll content in mung bean leaves where the seedlings showed stunted growth. The seedlings treated without and with chelated chromium complexes showed increased proline content as compared to control. The enzymatic study showed that, the catalase activity was maximum in shoots as compared to roots and the reverse is true in the case of peroxidase activity i.e. the roots showed higher value than that of the shoots.

Fluid extraction using carbon dioxide and organophosphorus chelating agents

Science.gov (United States)

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

1998-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2002-08-01

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

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

International Nuclear Information System (INIS)

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

1998-01-01

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

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

International Nuclear Information System (INIS)

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

1998-01-01

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

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

Science.gov (United States)

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 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.

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

Science.gov (United States)

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+ (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.

Effect of foliar application of amino acid and calcium chelate on some quality and quantity of Golden Delicious and Granny Smith apples

Directory of Open Access Journals (Sweden)

M. Arabloo

2017-03-01

Full Text Available In order to investigate the effects of foliar application of amino acid and calcium chelate on „Golden Delicious‟ and „Granny smith‟ apple trees, a randomized complete block design with four repetitions was conducted. Apple trees were sprayed with (0, 2, 4 mg L-1 of amino acid and (0, 2, 4 mg L-1 calcium chelate and their combination. Fruit weight, fruit firmness, total soluble solids, titretable acidity and calcium content of fruits were determined. All the applied treatments significantly increased quality and quantity traits compared to the control trees in both cultivars. The combination of amino acid and calcium chelate increased weight of both cultivars. Thus, in this study combination of amino acid and calcium chelate foliar spray treatment could be recommended from results as they significantly increased quality and quantity traits of „Golden delicious‟ and „Granny smith‟ apple trees.

Color stabilization of porcine hemoglobin during spray-drying and powder storage by combining chelating and reducing agents.

Science.gov (United States)

Salvador, P; Toldrà, M; Parés, D; Carretero, C; Saguer, E

2009-10-01

This work focuses on the effects of adding a chelating agent - such as nicotinic acid (NA, 2% w/v) or nicotinamide (Nam, 2.5% w/v) - along with glucose as a reducing agent (G, 10% w/v) to fresh porcine hemoglobin in order to stabilize its red color during spray-drying and powder storage at room temperature. Correlations between the CIELAB color parameters and the relative percentages of the different hemoglobin derivatives (liganded and deliganded ferrohemoglobin, and methemoglobin) were analyzed. The results indicate that, although little effects could be observed for any of the combined treatments on fresh hemoglobin, they were effective against pigment autoxidation during dehydration and subsequent storage. From the results, it can also be concluded that glucose was the main contributor to the color stabilization of the hemoglobin powder, probably due to its high water retention capacity.

[Reversed-phase high-performance liquid chromatograph--application to serum aluminium monitoring].

Science.gov (United States)

Hoshino, H; Kaneko, E

1996-01-01

High-Performance Liquid Chromatography (HPLC) with the reversed-phase partition mode separation (including ion-pair one) towards metal chelate compounds prepared in an off-line fashion (precolumn chelation) is most versatile in terms of high sensitivity with base-line flatness, unique selectivity and cost effectiveness. The extraordinary toughness to the complicated matrices encountered in clinical testing is exemplified by the successful application to the aluminium monitoring of human serum samples. The A1 chelate with 2,2'-dihydroxyazobenzene is efficiently chromatographed on a LiChroCART RP-18 column using an aqueous methanol eluent (63.6 wt%) containing tetrabutylammonium bromide as an ion-pair agent. The serum concentration level of A1 down to 6 micrograms dm-3 is readily monitored without influences from iron, chyle and haemolysis.

Comments on chelation therapy

International Nuclear Information System (INIS)

Wrenn, M.E.

1981-01-01

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

[Influences of the mobile phase constitution, salt concentration and pH value on retention characters of proteins on the metal chelate column].

Science.gov (United States)

Li, R; Di, Z M; Chen, G L

2001-09-01

The effects of the nature and concentration of salts, pH value and competitive eluent in the mobile phase on the protein retention have been systematically investigated. A mathematical expression describing the protein retention in metal chelate chromatography has been derived. It is proposed that the eluting power of the salt solution can be expressed by the eluent strength exponent epsilon. According to the retention characters of protein under different chromatographic conditions, the interaction between the various metal chelate ligands and proteins is discussed. The protein retention on the metal chelate column is a cooperative interactions of coordination, electrostatic and hydrophobic interaction. For the strong combined metal column with proteins such as IDA-Cu, the coordination is the most important, and the electrostatic interaction is secondary in chromatographic process. However, for the weak combined metal columns with proteins such as IDA-Ni, IDA-Co and IDA-Zn, the electrostatic interaction between the metal chelate ligands and proteins is the chief one, while the coordination is the next in importance. When the mobile phase contains high concentration of salt which can't form complex with the immobilized metal, the hydrophobic interaction between the protein and stationary phase will be increased. As the interaction between the metal chelate ligand and proteins relates to chromatographic operating conditions closely, different elution processes may be selected for different metal chelate columns. The gradient elution is generally performed by the low concentration of salt or different pH for weakly combined columns with proteins, however the competitive elution procedure is commonly utilized for strongly combined column. The experiment showed that NH3 is an excellent competitive eluent. It isn't only give the efficient separation of proteins, but also has the advantages of cheapness, less bleeding of the immobilized metals and ease of controlling NH3

Highly Efficient Interception and Precipitation of Uranium(VI) from Aqueous Solution by Iron-Electrocoagulation Combined with Cooperative Chelation by Organic Ligands.

Science.gov (United States)

Li, Peng; Zhun, Bao; Wang, Xuegang; Liao, PingPing; Wang, Guanghui; Wang, Lizhang; Guo, Yadan; Zhang, Weimin

2017-12-19

A new strategy combining iron-electrocoagulation and organic ligands (OGLs) cooperative chelation was proposed to screen and precipitate low concentrations (0-18.52 μmol/L) of uranium contaminant in aqueous solution. We hypothesized that OGLs with amino, hydroxyl, and carboxyl groups hydrophobically/hydrophilically would realize precuring of uranyl ion at pH electrocoagulation would achieve faster and more efficient uranium precipitation. Experimentally, the strategy demonstrated highly efficient uranium(VI) precipitation efficiency, especially with hydrophilic macromolecular OGLs. The uranium removal efficiency at optimized experimental condition reached 99.65%. The decrease of zeta potential and the lattice enwrapping between U-OGLs chelates and flocculation precursor were ascribed to the enhanced uranium precipitation activity. Uranium was precipitated as oxides of U(VI) or higher valences that were easily captured in aggregated micelles under low operation current potential. The actual uranium tailing wastewater was treated, and a satisfied uranium removal efficiency of 99.02% was discovered. After elution of the precipitated flocs, a concentrated uranium solution (up to 106.52 μmol/L) with very few other metallic impurities was obtained. Therefore, the proposed strategy could remove uranium and concentrate it concurrently. This work could provide new insights into the purification and recovery of uranium from aqueous solutions in a cost-effective and environmentally friendly process.

Overview of current chelation practices

Directory of Open Access Journals (Sweden)

Y. Aydinok

2011-12-01

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

Chelation in root canal therapy reconsidered.

Science.gov (United States)

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.

Biological behaviour of some 67Ga and 64Cu chelates

International Nuclear Information System (INIS)

Leonovicova, T.; Angelis, B.; Cifka, J.; Cifkova, I.

1984-01-01

Chelates of 67 Ga and 64 Cu with iminodiacetic acid (IDA) and its two phenyl derivatives as well as with nitrilotriacetic acid (NTA) and benzylnitrilotriacetic acid (BNTA) were prepared. All the chelates were found to be negatively charged. A study of the biological distribution of these chelates in rats during time intervals of 3 to 180 min showed that the chelate of 67 Ga with IDA substituted at a phenyl by a hydrophobic substituent is excreted by the kidneys into the urine at a much higher rate than the IDA chelate of 67 Ga. The excretion of NTA and BNTA chelates of 67 Ga is the opposite. Blood clearance of 64 Cu chelates is more rapid than that of 67 Ga chelates. Chelates of 64 Cu accumulate in the liver and with the bile are slowly excreted into the intestines, urinary excretion is negligible. (author)

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

Science.gov (United States)

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.

Interaction of Aluminum with PHFτ in Alzheimer’s Disease Neurofibrillary Degeneration Evidenced by Desferrioxamine-Assisted Chelating Autoclave Method

Science.gov (United States)

Murayama, Harunobu; Shin, Ryong-Woon; Higuchi, Jun; Shibuya, Satoshi; Muramoto, Tamaki; Kitamoto, Tetsuyuki

1999-01-01

To demonstrate that aluminum III (Al) interacts with PHFτ in neurofibrillary degeneration (NFD) of Alzheimer’s disease (AD) brain, we developed a “chelating autoclave method” that allows Al chelation by using trivalent-cationic chelator desferrioxamine. Its application to AD brain sections before Morin histochemistry for Al attenuated the positive fluorescence of neurofibrillary tangles, indicating Al removal from them. This method, applied for immunostaining with phosphorylation-dependent anti-τ antibodies, significantly enhanced the PHFτ immunoreactivity of the NFD. These results suggest that each of the phosphorylated epitopes in PHFτ are partially masked by Al binding. Incubation of AD sections with AlCl3 before Morin staining revealed Al accumulation with association to neurofibrillary tangles. Such incubation before immunostaining with the phosphorylation-dependent anti-τ antibodies abolished the immunolabeling of the NFD and this abolition was reversed by the Al chelation. These findings indicate cumulative Al binding to and thereby antigenic masking of the phosphorylated epitopes of PHFτ. Al binding was further documented for electrophoretically-resolved PHFτ on immunoblots, indicating direct Al binding to PHFτ. In vitro aggregation by AlCl3 was observed for PHFτ but was lost on dephosphorylation of PHFτ. Taken together, phosphorylation-dependent and direct PHFτ-Al interaction occurs in the NFD of the AD brain. PMID:10487845

Spectroscopy, modeling and computation of metal chelate solubility in supercritical CO2

International Nuclear Information System (INIS)

Brennecke, J.F.; Stadtherr, M.A.

1999-01-01

The overall objectives of this project were to gain a fundamental understanding of the solubility and phase behavior of metal chelates in supercritical CO 2 . Extraction with CO 2 is an excellent way to remove organic compounds from soils, sludges and aqueous solutions, and recent research has demonstrated that, together with chelating agents, it is a viable way to remove metals, as well. In this project the authors sought to gain fundamental knowledge that is vital to computing phase behavior, and modeling and designing processes using CO 2 to separate organics and metal compounds from DOE mixed wastes. The overall program was a comprehensive one to measure, model and compute the solubility of metal chelate complexes in supercritical CO 2 and CO 2 /cosolvent mixtures. Through a combination of phase behavior measurements, spectroscopy and the development of a new computational technique, the authors have achieved a completely reliable way to model metal chelate solubility in supercritical CO 2 and CO 2 /co-contaminant mixtures. Thus, they can now design and optimize processes to extract metals from solid matrices using supercritical CO 2 , as an alternative to hazardous organic solvents that create their own environmental problems, even while helping in metals decontamination

Chelate-assisted phytoextraction of lead from contaminated soils

Energy Technology Data Exchange (ETDEWEB)

Cooper, E.M.; Sims, J.T.; Cunningham, S.D.; Huang, J.W.; Berti, W.R.

1999-12-01

Phytoextraction, a remediation strategy for lead (Pb)-contaminated soils that removes soil Pb through plant uptake and harvest, may be enhanced by use of synthetic chelates. The authors evaluated Pb desorption from four contaminated soils by seven chelates (CDTA, DTPA, EDDHA, EFTA, HEDTA, HEIDA, and NTA) at three rates. The three most effective chelates (CDTA, DTPA, and HEDTA) were used in greenhouse studies with an uncontaminated soil and a Pb-contaminated soil to determine the effect of chelate type and rate on growth, Pb uptake, and plant elemental composition. Lead desorption varied with chelate and soil and increased with chelate rate, averaging 948 mg Pb kg{sup {minus}1} at the 20 mmol kg{sup {minus}1} rate vs. 28 mg Pb kg{sup {minus}1} by the control. The general ranking of chelate effectiveness, based on total Pb desorbed, was HEDTA > CDTA > DTPA > EGTA > HEIDA > EDDHA {approximately} NTA. Plant uptake of Pb from the contaminated soil was enhanced by CDTA, DTPA, and HEDTA, but with even the most effective treatment (corn, high CDTA rate), the amount of Pb extracted by plants was rather low. Lead extractable by the Toxicity Characteristic Leaching Procedure (TCLP) was increased from 9 mg L{sup {minus}1} in the control to from 47 to 174 mg L{sup {minus}1} in soils treated with 20 mmol kg{sup {minus}1} CDTA or DTPA and chelates generally caused a shift in Pb from resistant to more soluble chemical fractions.

[Susceptibility of enterococci to natural and synthetic iron chelators].

Science.gov (United States)

Lisiecki, Paweł; Mikucki, Jerzy

2002-01-01

A total of 79 strains of enterococci belonging to 10 species were tested for susceptibility to natural and synthetic iron chelators. All strains produced siderophores. These enterococci were susceptible to three synthetic iron chelators only: 8-hydroxyquinoline, disodium versenate (EDTA) and o-phenanthroline. They were resistant to all other synthetic chelators: ethylenediamine-di(o-hydroxyphenylacetic acid) (EDDHA), nitrilotriacetate, 2,2'-bipiridyl, salicylic acid, 8-hydroxy-5-sulphonic acid and to all natural chelators: ovotransferrine, human apotransferrine, horse apoferritine, desferrioxamine B, ferrichrome and rhodotorulic acid. The relations between susceptibility/resistance, iron assimilation and structure and stability constants of iron chelators were discussed.

Mixed ligand chelates of rare earths in aqueous solution

International Nuclear Information System (INIS)

Lakhani, S.U.; Thakur, G.S.; Sangal, S.P.

1981-01-01

Mixed ligand chelates of the 1:1 trivalent lanthanoids-EDTA, HEDTA and NTA chelates-1, 2-Dihydroxybenzene (Pyrocatechol) have been investigated at 35degC and 0.2 M ionic strength maintained by NaC10 4 . The formation of mixed ligand chelates has been found in all cases. The formation of mixed ligand chelates with EDTA shows the coordination number of lanthanoids to be eight, while the mixed ligand chelates with HEDTA and NTA shows the coordination number to be seven and six respectively. The stability constants of mixed ligand chelates are smaller than the binary complexes. The order of stability constants with respect to primary ligands follows the order NTA>HEDTA>EDTA. With respect to metal ions the stability constants increases with the decrease in ionic radii such as Gd< Er< Yb. (author)

f-Element Ion Chelation in Highly Basic Media

International Nuclear Information System (INIS)

Paine, Robert T.

1999-01-01

High-level radioactive waste (HLW) generated in the DOE complex is stored in tanks at several sites, but predominantly it is found at the Hanford reservation. Much of the material has been exposed to high pHs, consequently the waste exists in a complex, poorly understood mixture of solids, gels and solutions. The final waste remediation plan may involve chemical separation of fractions and a suitable, well developed molecular chemistry basis for performing these separations is not available. Indeed, the fundamental chemical behavior of most radioactive nuclides in basic media is not known. The goal of this project is to undertake fundamental studies of the coordination chemistry of f-element species in basic aqueous solutions containing common waste treatment ions (e.g., NO3 -, CO3 2-, organic carboxylates, and EDTA), as well as new waste scrubbing chelators produced in this study. The experimental agenda includes: 1. Studies of the speciation of Sr and Ln ions in basic solutions wit h and without common counterions; 2. Preparations of new multifunctional ligands that may act as strong, ion-specific chelators for Sr and/or Ln ions in basic media; and 3. Studies of the coordination and dissolution behavior of oxide-hydroxide species, as well as in insoluble sols, gels, and precipitates in combination with new chelating ligands. It is anticipated that this coordination chemistry will facilitate the design of advanced separation schemes required for handling the complex waste matrices found at the Hanford HLW facility

Chelation: Harnessing and Enhancing Heavy Metal Detoxification—A Review

Directory of Open Access Journals (Sweden)

Margaret E. Sears

2013-01-01

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

Chelating agents in pharmacology, toxicology and therapeutics

International Nuclear Information System (INIS)

1988-01-01

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

Exact analysis of Packet Reversed Packet Combining Scheme and Modified Packet Combining Scheme; and a combined scheme

International Nuclear Information System (INIS)

Bhunia, C.T.

2007-07-01

Packet combining scheme is a well defined simple error correction scheme for the detection and correction of errors at the receiver. Although it permits a higher throughput when compared to other basic ARQ protocols, packet combining (PC) scheme fails to correct errors when errors occur in the same bit locations of copies. In a previous work, a scheme known as Packet Reversed Packet Combining (PRPC) Scheme that will correct errors which occur at the same bit location of erroneous copies, was studied however PRPC does not handle a situation where a packet has more than 1 error bit. The Modified Packet Combining (MPC) Scheme that can correct double or higher bit errors was studied elsewhere. Both PRPC and MPC schemes are believed to offer higher throughput in previous studies, however neither adequate investigation nor exact analysis was done to substantiate this claim of higher throughput. In this work, an exact analysis of both PRPC and MPC is carried out and the results reported. A combined protocol (PRPC and MPC) is proposed and the analysis shows that it is capable of offering even higher throughput and better error correction capability at high bit error rate (BER) and larger packet size. (author)

Organically complexed copper, zinc, and chelating agents in the rivers of Western Puerto Rico

International Nuclear Information System (INIS)

Montgomery, J.R.; Echevarria, J.E.

1975-01-01

The method for determining soluble chelators gives their concentration in copper-equivalent chelating capacity units in fresh or slightly brackish (less than 3 percent salinity) water. The mean concentration of chelators in the Rio Guanajibo for December 1973 and January 1974 was 0.4 mg of copper per liter of water (N = 21, SD = 0.2) and for February 1974, 0.9 mg/liter (N = 8, SD = 0.4). The combined mean for the Rio Anasco and Culebrinas was 0.5 mg/liter (N = 7, SD = 0.4) in January and February 1974. The mean concentration of ionic copper was 0.5 μg/liter (N = 7, SD = 0.6) and of ionic zinc, 0.2 μg/liter (N = 8, SD = 0.1) in the Rio Guanajibo from November 1972 to February 1973. The concentration of organically bound copper was 0.3 μ/liter (N = 7, SD = 0.2) and that of organically bound zinc was 0.6 μg/liter (N = 8, SD = 0.6); this indicates that there was more than a sufficient quantity of chelator available in the river to complex all the soluble copper. The presence of a high ratio of Ca 2+ to Cu 2+ probably prevents the formation of larger concentrations of organically complexed copper. The mean concentration of chelating agents in the Guanajibo River seems to be directly related to the increased organic input from municipalities and a sugar mill. The concentration of chelators in tropical rivers appears to be higher than that found in Canadian lakes. The mean concentration for particulate organic carbon (POC) was 3653 μg atoms/liter (SD = 3653, N = 29). The dissolved reactive phosphate (DRP) ranged from a mean of 1.1 μg atom/liter. No significant correlation could be found between POC, DRP, and the concentration of chelators

Study on the mutagenic effects of a new chelating agent (7603) used for accelerating excretion of radionuclides

International Nuclear Information System (INIS)

Shen Binyuan; Luo Meichu; Zhen Guibao; Ruan Tianming; Feng Jialin; Cao Qunli

1989-01-01

The results of studies on the mutagenic effects of a new chelating agent, Suo An Quan (7603) or 5-methxlene Iminodiaeticaid Vanillin, was reported in this paper. For this agent, no mutagenesis was found by the reverse mutation test of Salmonella typhi munine (Amos test), the test of chromosome aberrations in Chinese hamster oocytes (CHO cells), and the test of micronucleus in polychromatic erythrocytes of the bone marrow in mice

Topical efficacy of dimercapto-chelating agents against lewisite-induced skin lesions in SKH-1 hairless mice

Energy Technology Data Exchange (ETDEWEB)

Mouret, Stéphane, E-mail: stephane.mouret@irba.fr [Département de Toxicologie et Risques Chimiques, Institut de Recherche Biomédicale des Armées, Centre de Recherches du Service de Santé des Armées, 24 avenue Maquis du Grésivaudan, 38700 La Tronche (France); Wartelle, Julien; Emorine, Sandy; Bertoni, Marine; Nguon, Nina; Cléry-Barraud, Cécile [Département de Toxicologie et Risques Chimiques, Institut de Recherche Biomédicale des Armées, Centre de Recherches du Service de Santé des Armées, 24 avenue Maquis du Grésivaudan, 38700 La Tronche (France); Dorandeu, Frédéric [Département de Toxicologie et Risques Chimiques, Institut de Recherche Biomédicale des Armées, Centre de Recherches du Service de Santé des Armées, 24 avenue Maquis du Grésivaudan, 38700 La Tronche (France); Ecole du Val-de-Grâce, 1 place Alphonse Laveran, Paris (France); Boudry, Isabelle [Département de Toxicologie et Risques Chimiques, Institut de Recherche Biomédicale des Armées, Centre de Recherches du Service de Santé des Armées, 24 avenue Maquis du Grésivaudan, 38700 La Tronche (France)

2013-10-15

Lewisite is a potent chemical warfare arsenical vesicant that can cause severe skin lesions. Today, lewisite exposure remains possible during demilitarization of old ammunitions and as a result of deliberate use. Although its cutaneous toxicity is not fully elucidated, a specific antidote exists, the British anti-lewisite (BAL, dimercaprol) but it is not without untoward effects. Analogs of BAL, less toxic, have been developed such as meso-2,3-dimercaptosuccinic acid (DMSA) and have been employed for the treatment of heavy metal poisoning. However, efficacy of DMSA against lewisite-induced skin lesions remains to be determined in comparison with BAL. We have thus evaluated in this study the therapeutic efficacy of BAL and DMSA in two administration modes against skin lesions induced by lewisite vapor on SKH-1 hairless mice. Our data demonstrate a strong protective efficacy of topical application of dimercapto-chelating agents in contrast to a subcutaneous administration 1 h after lewisite exposure, with attenuation of wound size, necrosis and impairment of skin barrier function. The histological evaluation also confirms the efficacy of topical application by showing that treatments were effective in reversing lewisite-induced neutrophil infiltration. This protective effect was associated with an epidermal hyperplasia. However, for all the parameters studied, BAL was more effective than DMSA in reducing lewisite-induced skin injury. Together, these findings support the use of a topical form of dimercaprol-chelating agent against lewisite-induced skin lesion within the first hour after exposure to increase the therapeutic management and that BAL, despite its side-effects, should not be abandoned. - Highlights: • Topically applied dimercapto-chelating agents reduce lewisite-induced skin damage. • One topical application of BAL or DMSA is sufficient to reverse lewisite effects. • Topical BAL is more effective than DMSA to counteract lewisite-induced skin damage.

Role of chelates in magnetic resonance imaging studies

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Tripathi Laxmi

2009-01-01

Full Text Available Imaging studies are tests performed with a variety of techniques that produce pictures of the inside of a patient′s body. Magnetic resonance imaging (MRI is an imaging technique based on the principles of nuclear magnetic resonance. MRI uses a powerful magnetic field, radio waves, and a computer to produce detailed pictures of organs, soft tissues, bone, and virtually all other internal body structures. Chelates have a wide application in such imaging techniques. Chelates in imaging studies are used alone as radioactive agents or conjugated to monoclonal antibodies or to DNA as radioactive agents. Technetium chelates and gadolinium chelates are being widely used as magnetic resonance contrast media.

Copper and Zinc Chelation as a Treatment of Alzheimer's Disease

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Hodak, Miroslav; Bernholc, Jerry

2014-03-01

Alzheimer's disease (AD) is a neurodegenerative disorder affecting millions of people in the U.S. The cause of the disease remains unknown, but amyloid- β (A β), a short peptide, is considered causal its pathogenesis. At cellular level, AD is characterized by deposits mainly composed of A β that also contain elevated levels of transition metals ions. Targeting metals is a promising new strategy for AD treatment, which uses moderately strong metal chelators to sequester them from A β or the environment. PBT2 is a chelating compound that has been the most promising in clinical trials. In our work, we use computer simulations to investigate complexes of a close analog of PBT2 with Cu2+ and Zn2+ ions. The calculations employ KS/FD DFT method, which combines Kohn-Sham DFT with the frozen-density DFT to achieve efficient description of explicit solvent beyond the first solvation shell. Our work is based on recent experiments and examines both 1:1 and 2:1 chelator-metal stochiometries detected experimentally. The results show that copper attaches more strongly than zinc, find that 1:1 complexes involve water in the first coordination shell and determine which one of several possible 2:1 geometries is the most preferable.

Trade-off between synergy and efficacy in combinations of HIV-1 latency-reversing agents.

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Gupta, Vipul; Dixit, Narendra M

2018-02-01

Eradicating HIV-1 infection is difficult because of the reservoir of latently infected cells that gets established soon after infection, remains hidden from antiretroviral drugs and host immune responses, and retains the capacity to reignite infection following the cessation of treatment. Drugs called latency-reversing agents (LRAs) are being developed to reactivate latently infected cells and render them susceptible to viral cytopathicity or immune killing. Whereas individual LRAs have failed to induce adequate reactivation, pairs of LRAs have been identified recently that act synergistically and hugely increase reactivation levels compared to individual LRAs. The maximum synergy achievable with LRA pairs is of clinical importance, as it would allow latency-reversal with minimal drug exposure. Here, we employed stochastic simulations of HIV-1 transcription and translation in latently infected cells to estimate this maximum synergy. We incorporated the predominant mechanisms of action of the two most promising classes of LRAs, namely, protein kinase C agonists and histone deacetylase inhibitors, and quantified the activity of individual LRAs in the two classes by mapping our simulations to corresponding in vitro experiments. Without any adjustable parameters, our simulations then quantitatively captured experimental observations of latency-reversal when the LRAs were used in pairs. Performing simulations representing a wide range of drug concentrations, we estimated the maximum synergy achievable with these LRA pairs. Importantly, we found with all the LRA pairs we considered that concentrations yielding the maximum synergy did not yield the maximum latency-reversal. Increasing concentrations to increase latency-reversal compromised synergy, unravelling a trade-off between synergy and efficacy in LRA combinations. The maximum synergy realizable with LRA pairs would thus be restricted by the desired level of latency-reversal, a constrained optimum we elucidated with

Obligatory reduction of ferric chelates in iron uptake by soybeans.

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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.

A randomized, controlled study evaluating effects of amlodipine addition to chelators to reduce iron loading in patients with thalassemia major.

Science.gov (United States)

Eghbali, Aziz; Kazemi, Hamideh; Taherahmadi, Hassan; Ghandi, Yazdan; Rafiei, Mohammad; Bagheri, Bahador

2017-12-01

Cardiomyopathy due to iron overload can be fatal in patients with thalassemia major. Calcium channel blockers seem to be effective to reduce iron loading. Our goal was to study effects of amlodipine addition to chelators on iron loading in patients with thalassemia major. This randomized, controlled, and single-center trial was performed on 56 patients with thalassemia major. Patients were randomized 1:1 to combined group (iron chelator plus amlodipine) or control group (iron chelator) for 1 year. Iron content was measured by magnetic resonance imaging; heart T2*, and liver T2*. Serum ferritin was also measured. After 12 months of treatment, myocardial T2* values had significant improvement in combined group (21.9 ± 8.0 ms to 24.5 ± 7.6 ms; P < .05); Difference between two groups was significant (P = .02). Combined treatment had no effect on hepatic T2* value (9.6 ± 2.8 ms to 9.5 ± 3.6 ms); difference between two groups was not significant (P = .2). In addition, a significant reduction was seen in serum ferritin levels in two groups. Mild gastrointestinal upset was the most common untoward effect. Addition of amlodipine to iron chelators has beneficial effects for reduction of iron loading in patients with thalassemia major. This combination therapy seems safe. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

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

International Nuclear Information System (INIS)

Crosby, W.H.; Green, R.

1982-01-01

Iron chelators were screened in an iron-loaded rat model using selective radioiron probes. In all experiments, chelators D and F, in that order, induced significant loss of radioiron compared with controls. However, use of chelator D was associated with side effects, and resulted in the death of some animals. There was some evidence that chelator A also caused iron loss significantly greater than controls. Chelators B, C and E were without apparent enhancing effect on radioiron excretion. This was a blind study and the compounds used were A - 2,3-Dihydroxybenzoic acid; B - N,N1-Dimethyladipohydroxamic acid; C - DL-Phenylalanine hydroxamic acid; D - Ethylenediamine-N,N1-bis(2-hydroxphenylacetic acid); E - Propionohydroxamic acid; and F - Deferrioxamine B

Removal of inhaled 241Am oxide particles from beagle dogs by combined treatment with lung lavage and a chelating agent

International Nuclear Information System (INIS)

Muggenburg, B.A.; Mewhinney, J.A.; Mo, T.; Slauson, D.O.

1978-01-01

This experiment was performed to evaluate combined therapy of lung lavage and chelation treatments to remove inhaled particles of 241 Am oxide. Twenty-four Beagle dogs were divided into four groups of 6 dogs each. Each group was exposed to an aerosol of different-sized particles of 241 Am oxide: monodisperse particles with AD of 0.75, 1.5 or 3.0 μm; polydisperse particles with AMAD = 1.5 μm. Three dogs in each group were treated with 5 lung lavages of the right lung (day 2, 7, 14, 28 and 42), and 5 lavages of the left lung (days 2, 10, 21, 35, and 49). In addition, each of the treated dogs was given 22 μmoles of trisodium calcium diethylenetriaminepentaacetate (Na 3 Ca DTPA) by intravenous injection 18 times from day 1 to 52 after exposure. The remaining 3 dogs in each group were untreated control dogs. All of the dogs were sacrificed 64 days after exposure and tissues, excreta, and lavage fluids were analyzed for 241 Am activity. Tissue distribution of 241 Am activity at sacrifice varied with aerosol particle size. Less 241 Am activity was found in the lungs of the dogs exposed to 0.75 and 1.5 μm AD aerosols groups than in those exposed to 3.0 μm particles. Lung lavage removed from 24 to 58% of the initial lung burden (ILB). Particle size did not affect the usefulness of lung lavage but it did influence the effectiveness of Na 3 Ca DTPA treatment. Na 3 Ca DTPA enhanced urinary excretion of 241 Am; dogs exposed to 0.75 μm particles excreted 31% of the ILB, and those exposed to 3.0 μm particles excreted only 10%. This experiment showed the effectiveness of combined treatment with lung lavage and chelation therapy for the removal of 241 Am oxide in the first 64 days after exposure. (author)

Bright, Multi-responsive, Sky-Blue Platinum(II) Phosphors Based on a Tetradentate Chelating Framework.

Science.gov (United States)

Liu, Lijie; Wang, Xiang; Wang, Nan; Peng, Tai; Wang, Suning

2017-07-24

A new class of highly efficient and stable, blue-phosphorescent Pt II complexes based on a tetradentate chelating framework has been found to exhibit highly sensitive and reversible responses to multiple external stimuli including temperature, pressure, and UV irradiation with distinct phosphorescent color switching-from blue to red or white. Intermolecular excimer formation is the main origin of this intriguing multi-response phenomenon. Highly efficient singlet-oxygen sensitization by the Pt II compounds yields UV-light-induced phosphorescence enhancement and color switching. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

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Anthea Johnson

2015-10-01

Full Text Available 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.

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

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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.

Metal regeneration of iron chelates in nitric oxide scrubbing

Science.gov (United States)

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.

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

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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.

Metallomics for Alzheimer's disease treatment: Use of new generation of chelators combining metal-cation binding and transport properties.

Science.gov (United States)

D'Acunto, Cosimo Walter; Kaplánek, Robert; Gbelcová, Helena; Kejík, Zdeněk; Bříza, Tomáš; Vasina, Liudmila; Havlík, Martin; Ruml, Tomáš; Král, Vladimír

2018-04-25

Alzheimer's disease (AD) is a progressive neurodegenerative disorder affecting tens of million people. Currently marketed drugs have limited therapeutic efficacy and only slowing down the neurodegenerative process. Interestingly, it has been suggested that biometal cations in the amyloid beta (Aβ) aggregate deposits contribute to neurotoxicity and degenerative changes in AD. Thus, chelation therapy could represent novel mode of therapeutic intervention. Here we describe the features of chelators with therapeutically relevant mechanism of action. We have found that the tested compounds effectively reduce the toxicity of exogenous Aβ and suppress its endogenous production as well as decrease oxidative stress. Cholyl hydrazones were found to be the most active compounds. In summary, our data show that cation complexation, together with improving transport efficacy may represent basis for eventual treatment strategy in AD. Copyright © 2018. Published by Elsevier Masson SAS.

Use of chelating agents as immovable phase in extraction chromatography

International Nuclear Information System (INIS)

Sebesta, F.

1978-01-01

Extraction chromatography using chelating agents is reviewed. The theory of element extraction by chelating agents and factors influencing this process (pH, extracting agent concentration in organic phase, masking agent concentration in aqueous phase) are briefly considered. The effect of kinetic factors on the extraction chromatography process is discussed. Ways of preparing columns are emphasized. Examples of using chelating reagents in various extraction chromatography systems are given. β-Diketones, oximes, hydroxamic acids, dithizon, diethyl dithiocarbamic acid are chosen as chelating agents

Modeling the chelation of As(III) in lewisite by dithiols using density functional theory and solvent-assisted proton exchange.

Science.gov (United States)

Harper, Lenora K; Bayse, Craig A

2015-12-01

Dithiols such as British anti-lewisite (BAL, rac-2,3-dimercaptopropanol) are an important class of antidotes for the blister agent lewisite (trans-2-chlorovinyldichloroarsine) and, more generally, are chelating agents for arsenic and other toxic metals. The reaction of the vicinal thiols of BAL with lewisite through the chelation of the As(III) center has been modeled using density functional theory (DFT) and solvent-assisted proton exchange (SAPE), a microsolvation method that uses a network of water molecules to mimic the role of bulk solvent in models of aqueous phase chemical reactions. The small activation barriers for the stepwise SN2-type nucleophilic attack of BAL on lewisite (0.7-4.9kcal/mol) are consistent with the favorable leaving group properties of the chloride and the affinity of As(III) for soft sulfur nucleophiles. Small, but insignificant, differences in activation barriers were found for the initial attack of the primary versus secondary thiol of BAL and the R vs S enantiomer. An examination of the relative stability of various dithiol-lewisite complexes shows that ethanedithiols like BAL form the most favorable chelation complexes because the angles formed in five-membered ring are most consistent with the hybridization of As(III). More obtuse S-As-S angles are required for larger chelate rings, but internal As⋯N or As⋯O interactions can enhance the stability of moderate-sized rings. The low barriers for lewisite detoxification by BAL and the greater stability of the chelation complexes of small dithiols are consistent with the rapid reversal of toxicity demonstrated in previously reported animal models. Copyright © 2015 Elsevier Inc. All rights reserved.

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

International Nuclear Information System (INIS)

Manwar, S.; Iram, S.

2014-01-01

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

Characterization of amorphous yttria layers deposited by aqueous solutions of Y-chelate alkoxides complex

Science.gov (United States)

Kim, Young-Soon; Lee, Yu-Ri; Kim, Byeong-Joo; Lee, Jae-Hun; Moon, Seung-Hyun; Lee, Hunju

2015-01-01

Crack-free amorphous yttria layers were deposited by dip coating in solutions of different Y-chelate alkoxides complex. Three Y-chelate solutions of different concentrations were prepared using yttrium acetate tetrahydrate, yttrium stearic acid as Y source materials. PEG, diethanolamine were used as chelating agents, while ethanol, methanol and tetradecane were used as solvent. Three different combinations of chelating and solvents were used to prepare solutions for Y2O3 dip coating on SUS, electropolished and non-electropolished Hastelloy C-276 substrates. The thickness of the films was varied by changing the number of dipping cycles. At an optimized condition, the substrate surface roughness (rms) value was reduced from ∼50 nm to ∼1 nm over a 10 × 10 μm2 area. After Y2O3 deposition, MgO was deposited using ion-beam assisted deposition (IBAD), then LaMnO3 (LMO) was deposited using sputtering and GdBCO was deposited using reactive co-evaporation by deposition and reaction (RCE-DR). Detailed X-ray study indicates that LMO/MgO/Y2O3 and GdBCO/LMO/MgO/Y2O3 stack films have good out-of-plane and in-plane textures with strong c-axis alignment. The critical current (Ic) of GdBCO/LMO/MgO/Y2O3 multilayer structure varied from 190 to 420 A/cm with different solutions, when measured at 77 K. These results demonstrated that amorphous yttria can be easily deposited by dip coating using Y-chelates complex as a diffusion barrier and nucleation layer.

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

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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.

Chelation therapy to prevent diabetes-associated cardiovascular events.

Science.gov (United States)

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.

Curcumin induces apoptosis and protective autophagy in castration-resistant prostate cancer cells through iron chelation

Directory of Open Access Journals (Sweden)

Yang C

2017-02-01

Full Text Available Chunguang Yang,1,* Xueyou Ma,1,* Zhihua Wang,1 Xing Zeng,1 Zhiquan Hu,1 Zhangqun Ye,1 Guanxin Shen2 1Department of Urology, Tongji Hospital, 2Department of Immunology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, People’s Republic of China *These authors contributed equally to this work Background: Curcumin induces apoptosis and autophagy in different cancer cells. Moreover, chemical and biological experiments have evidenced that curcumin is a biologically active iron chelator and induces cytotoxicity through iron chelation. We thus hypothesized that curcumin may induce apoptosis and autophagy in castration-resistant prostate cancer (CRPC cells through its iron-chelating properties.Materials and methods: CRPC cells were loaded with curcumin alone or in combination with ferric ammonium citrate (FAC. Cytotoxicity was measured by 3-(4,5-dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide (MTT assay. Apoptosis was assessed by flow cytometry, terminal deoxynucleotidyl transferase nick end labeling (TUNEL assay and caspase activity. Autophagy status was analyzed by the detection of autophagosomes and light chain 3-II (LC3-II using transmission electron microscopy and Western blot. Iron-binding activity of curcumin was assessed by spectrophotometry and MTT assay. The expression levels of transferrin receptor 1 (TfR1 and iron regulatory protein 1 (IRP1 were examined by Western blot.Results: Curcumin induced apoptosis and autophagy in CRPC cells. Combining curcumin with autophagy inhibitors (3-methyladenine [3-MA] synergized the apoptotic effect of curcumin. Moreover, curcumin bound to FAC at a ratio of ~1:1, as assessed by spectrophotometry and MTT assay. Apoptosis and autophagy induced by curcumin were counteracted by equal amounts of FAC. At apoptosis- and autophagy-inducing concentrations, curcumin enhanced the expression levels of TfR1 and IRP1, indicative of iron deprivation induced by curcumin

Effect of the ultrasound-Fenton oxidation process with the addition of a chelating agent on the removal of petroleum-based contaminants from soil.

Science.gov (United States)

Li, Ying; Li, Fangmin; Li, Fanxiu; Yuan, Fuqian; Wei, Pingfang

2015-12-01

The effects of ultrasonic irradiation, the chelating agent modified Fenton reaction, and a combination of ultrasound and the Fenton method in removing petroleum contaminants from a soil were studied. The results showed that the contaminant removal rate of the Fenton treatment combined with an oxalic acid chelating agent was 55.6% higher than that without a chelating agent. The average removal rate of the contaminants using the ultrasound-Fenton treatment was 59.0% higher than that without ultrasonic treatment. A combination of ultrasound and an Fe(2+)/Fe(3+)-oxalate complex-modified Fenton reagent resulted in significantly higher removal rates of n-alkanes (C(n)H(2n+2), n Fenton method. The Fenton reaction and the ultrasound-Fenton treatment can unselectively remove multiple components of residual hydrocarbons and a number of benzene rings in polycyclic aromatic hydrocarbons. The chemistry of the heterocyclic compounds and the position and number of substituents can affect the degradation process.

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

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Sheng-Teng Huang

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

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

International Nuclear Information System (INIS)

Alassbaly, F.S.; Ajaily, M.M.E.

2014-01-01

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

Metal chelate process to remove pollutants from fluids

Science.gov (United States)

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.

Bifunctional chelates of Rh-105 and Au-199 as potential radiotherapeutic agents

International Nuclear Information System (INIS)

Troutner, D.E.; Schlemper, E.O.

1990-01-01

Since last year we have: continued the synthesis of pentadentate bifunctional chelating agents based on diethylene triamine; studied the chelation Rh-105, Au-198 (as model for Au-199) and Tc-99m with these agents as well as chelation of Pd-109, Cu-67, In-111, and Co-57 with some of them; synthesized a new class of potential bifunctional chelating agents based on phenylene diamine; investigated the behavior of Au-198 as a model for Au-199; begun synthesis of bifunctional chelating agents based on terpyridly and similar ligands; and continued attempts to produce tetradentate bifunctional chelates based on diaminopropane. Each of these will be addressed in this report

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

Science.gov (United States)

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.

Laccase Immobilization by Chelated Metal Ion Coordination Chemistry

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Qingqing Wang

2014-09-01

Full Text Available In this work, amidoxime polyacrylonitrile (AOPAN nanofibrous membrane was prepared by a reaction between PAN nanofibers and hydroxylamine hydrochloride. The AOPAN nanofibrous membranes were used for four metal ions (Fe3+, Cu2+, Ni2+, Cd2+ chelation under different conditions. Further, the competition of different metal ions coordinating with AOPAN nanofibrous membrane was also studied. The AOPAN chelated with individual metal ion (Fe3+, Cu2+, Ni2+, Cd2+ and also the four mixed metal ions were further used for laccase (Lac immobilization. Compared with free laccase, the immobilized laccase showed better resistance to pH and temperature changes as well as improved storage stability. Among the four individual metal ion chelated membranes, the stability of the immobilized enzymes generally followed the order as Fe–AOPAN–Lac > Cu–AOPAN–Lac > Ni–AOPAN–Lac > Cd–AOPAN–Lac. In addition, the immobilized enzyme on the carrier of AOPAN chelated with four mixed metal ions showed the best properties.

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

Science.gov (United States)

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.

f-Element Ion Chelation in Highly Basic Media

International Nuclear Information System (INIS)

Paine, R.T.

2000-01-01

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

Chelating agents as stationary phase in extraction chromatography, ch. 11

International Nuclear Information System (INIS)

Sebesta, F.

1975-01-01

Chelating agents have been used largely in extraction chromatography for separations related to activation analysis, for concentration of metals from dilute solutions, and for preparation of radiochemically pure or carrier-free radionuclides. This review deals with the theory of extraction by chelating agents, the experimental technique, and the chelating agents and systems used (β-diketones, oximes, hydroxamic acid, dithizone and diethyldithiocarbamic acid)

Sequestration of chelated copper by structural Fe(II): Reductive decomplexation and transformation of Cu{sup II}-EDTA

Energy Technology Data Exchange (ETDEWEB)

He, Hongping [State Key Laboratory of Pollution Control and Resources Reuse, School of Environmental Science & Engineering, Tongji University, Shanghai 200092 (China); Wu, Deli, E-mail: wudeli@tongji.edu.cn [State Key Laboratory of Pollution Control and Resources Reuse, School of Environmental Science & Engineering, Tongji University, Shanghai 200092 (China); Zhao, Linghui [State Key Laboratory of Pollution Control and Resources Reuse, School of Environmental Science & Engineering, Tongji University, Shanghai 200092 (China); Luo, Cong [School of Civil and Environmental Engineering, Georgia Institute of Technology, GA 30332 (United States); Dai, Chaomeng; Zhang, Yalei [State Key Laboratory of Pollution Control and Resources Reuse, School of Environmental Science & Engineering, Tongji University, Shanghai 200092 (China)

2016-05-15

Highlights: • Structural Fe(II) was found to reveal high sequestration potential in various chelated copper. • Chelated copper was reduced to Cu(0) and Cu{sub 2}O by =Fe(II), whcih was oxidized to Fe{sub 2}O{sub 3}·H{sub 2}O. • Both electron transfer and surface =Fe(II) were found to be crucial during chelated copper reduction. • The indispensible role of reductive decomplexation was identified in chelated copper sequestration. - Abstract: Chelated coppers, such as Cu{sup II}-EDTA, are characteristically refractory and difficult to break down because of their high stability and solubility. Cu{sup II}–EDTA sequestration by structural Fe(II) (=Fe(II)) was investigated intensively in this study. Up to 101.21 mgCu(II)/gFe(II) was obtained by =Fe(II) in chelated copper sequestration under near neutral pH condition (pH 7.70). The mechanism of Cu{sup II}-EDTA sequestration by =Fe(II) was concluded as follows: 3Cu{sup II}–EDTA + 7=Fe(II) + 9H{sub 2}O → Cu(0) ↓ + Cu{sub 2}O ↓ (the major product) + 2Fe{sub 2}O{sub 3}·H{sub 2}O ↓ + 3Fe{sup II}–EDTA +14H{sup +} Novel results strongly indicate that Cu{sup II} reductive transformation induced by surface =Fe(II) was mainly responsible for chelated copper sequestration. Cu(0) generation was initially facilitated, and subsequent reduction of Cu(II) into Cu(I) was closely combined with the gradual increase of ORP (Oxidation-Reduction Potential). Cu-containing products were inherently stable, but Cu{sub 2}O would be reoxidized to Cu(II) with extra-aeration, resulting in the release of copper, which was beneficial to Cu reclamation. Concentration diminution of Cu{sup II}–EDTA within the electric double layer and competitive adsorption were responsible for the negative effects of Ca{sup 2+}, Mg{sup 2+}. By generating vivianite, PO{sub 4}{sup 3−} was found to decrease surface =Fe(II) content. This study is among the first ones to identify the indispensible role of reductive decomplexation in chelated copper

The adsorption of chelating reagents on oxide minerals

International Nuclear Information System (INIS)

Bryson, M.A.W.

1984-06-01

This work constitutes a fundamental study of the interaction between chelating reagents and oxide minerals. The adsorption mechanisms have been elucidated for most of the systems generated by the oxides of copper(II) or iron(III) and chelating reagents octyl hydroxamate, N-phenylbenzohydroxamate, salicylaldoxime, 5-nitro-salicylaldoxime or 8-hydroxyquinoline. In order to better understand the adsorption process associated with copper(II) oxide, the oxide was recrystallized to produce a coarser material with a more uniform surface. This allowed the oxide surface to be viewed under the scanning electron microscope. A detailed investigation of the effect of the system variables; pH, conditioning period, concentration, temperature, surface area and dispersing reagent on the rate of precipitation of the copper chelate species of general form, Cu(chel) 2 , was made. In addition the chemical nature of the adsorbed species and the structural form of the precipitates were determined with the aid of infra-red spectroscopy and the scanning electron microscope. On the basis of these results a model has been formulated for the adsorption processes. The precipitation process was examined in more detail by the study of the adsorption of chelate on copper metal. Contact angle measurements of air bubbles on copper metal conditioned with chelate were related to the adsorption results in an attempt to isolate the optimum conditions for flotation of oxide minerals

Labelling of bacteria with indium chelates

International Nuclear Information System (INIS)

Kleinert, P.; Pfister, W.; Endert, G.; Sproessig, M.

1985-01-01

The indium chelates were prepared by reaction of radioactive indiumchloride with 10 μg oxine, 15 μg tropolone and 3 mg acetylacetone, resp. The formed chelates have been incubated with 10 9 germs/ml for 5 minutes, with labelling outputs from 90 to 95%. Both gram-positive (Streptococcus, Staphylococcus) and gram-negative bacteria (Escherichia coli) can be labelled. The reproductive capacity of the bacteria was not impaired. The application of indium labelled bacteria allows to show the distribution of microorganisms within the living organism and to investigate problems of bacterial adherence. (author)

Review of actinide decorporation with chelating agents

Energy Technology Data Exchange (ETDEWEB)

Ansoborlo, E. [CEA Valrho, Dir. de l' Energie Nucleaire (DEN/DRCP/CETAMA), 30 - Marcoule (France); Amekraz, B.; Moulin, Ch. [CEA Saclay, Dept. de Physico-Chimie (DEN/DPC/SECR), 91 - Gif sur Yvette (France); Moulin, V. [CEA Saclay, Dir. du Developpement et de l' Innovation Nucleares (DEN/DDIN/MR), 91 - Gif Sur Yvette (France); Taran, F. [CEA Saclay (DSV/DBJC/SMMCB), 91 - Gif-sur-Yvette (France); Bailly, Th.; Burgada, R. [Centre National de la Recherche Scientifique (CNRS/LCSB/UMR 7033), 93 - Bobigny (France); Henge-Napoli, M.H. [CEA Valrho, Site de Marcoule (INSTN), 30 (France); Jeanson, A.; Den Auwer, Ch.; Bonin, L.; Moisy, Ph. [CEA Valrho, Dir. de l' Energie Nucleaire (DEN/DRCP/SCPS), 30 - Marcoule (France)

2007-10-15

In case of accidental release of radionuclides in a nuclear facility or in the environment, internal contamination (inhalation, ingestion or wound) with actinides represents a severe health risk to human beings. It is therefore important to provide effective chelation therapy or decorporation to reduce acute radiation damage, chemical toxicity, and late radiation effects. Speciation governs bioavailability and toxicity of elements and it is a prerequisite tool for the design and success of new ligands or chelating agents. The purpose of this review is to present the state-of-the-art of actinide decorporation within biological media, to recall briefly actinide metabolism, to list the basic constraints of actinide-ligand for development, to describe main tools developed and used for decorporation studies, to review mainly the chelating agents tested for actinides, and finally to conclude on the future trends in this field. (authors)

Radiopharmaceutical chelates and method of external imaging

International Nuclear Information System (INIS)

1976-01-01

The preparation of the following chemicals is described: chelates of technetium-99m, cobalt-57, gallium-67, gallium-68, indium-111 or indium-113m and a substituted iminodiacetic acid or an 8-hydroxyquinoline useful as a radiopharmaceutical external imaging agent. The compounds described are suitable for intravenous injection, have an excellent in vivo stability and are good organ seekers. Tin(II) choride or other tin(II) compounds are used as chelating agents

CARDIAC FUNCTION AND IRON CHELATION IN THALASSEMIA MAJOR AND INTERMEDIA: A REVIEW OF THE UNDERLYING PATHOPHYSIOLOGY AND APPROACH TO CHELATION MANAGEMENT

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Athanasios Aessopos

2009-07-01

Full Text Available Heart disease is the leading cause of mortality and one of the main causes of morbidity in beta-thalassemia. Patients with homozygous thalassemia may have either a severe phenotype which is usually transfusion dependent or a milder form that is thalassemia intermedia.  The two main factors that determine cardiac disease in homozygous β thalassemia are the high output state that results from chronic tissue hypoxia, hypoxia-induced compensatory reactions and iron overload.  The high output state playing a major role in thalassaemia intermedia and the iron load being more significant in the major form. Arrhythmias, vascular involvement that leads to an increased pulmonary vascular resistance and an increased systemic vascular stiffness and valvular abnormalities also contribute to the cardiac dysfunction in varying degrees according to the severity of the phenotype.  Endocrine abnormalities, infections, renal function and medications can also play a role in the overall cardiac function.  For thalassaemia major, regular and adequate blood transfusions and iron chelation therapy are the mainstays of management. The approach to thalassaemia intermedia, today, is aimed at monitoring for complications and initiating, timely, regular transfusions and/or iron chelation therapy.  Once the patients are on transfusions, then they should be managed in the same way as the thalassaemia major patients.  If cardiac manifestations of dysfunction are present in either form of thalassaemia, high pre transfusion Hb levels need to be maintained in order to reduce cardiac output and appropriate intensive chelation therapy needs to be instituted.  In general recommendations on chelation, today, are usually made according to the Cardiac Magnetic Resonance findings, if available.  With the advances in the latter technology and the ability to tailor chelation therapy according to the MRI findings as well as the availability of three iron chelators, together with

Phenolic aminocarboxylic acids - new chelating agents for modifying gallium-67 biodistribution

Energy Technology Data Exchange (ETDEWEB)

Hunt, F.C.; Maddalena, D.J. (Australian Atomic Energy Commission Research Establishment, Lucas Heights)

The chelating agents EDDHA and HBED were synthesised with carboxyl or sulphonyl groups in the phenolic ring to favour urinary excretion on complexing with gallium. Carboxyl EDDMA was administered to tumor-bearing rats, and its concentration in the tumours and other tissues determined by scintigraphic imaging. The chelating agents increase tumour to blood ratios by chelating gallium in vivo.

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

Science.gov (United States)

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

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

Energy Technology Data Exchange (ETDEWEB)

Ilaiyaraja, P.; Venkatraman, B., E-mail: chemila07@gmail.com [Radiological Safety Division, Indira Gandhi Centre for Atomic Research, Kalpakkam (India); Deb, A.K. Singha [Chemical Engineering Division, Bhabha Atomic Research Centre, Mumbai (India); Ponraju, D. [Safety Engineering Division, Indira Gandhi Centre for Atomic Research, Kalpakkam (India); Ali, Sk. Musharaf [Chemical Engineering Division, Bhabha Atomic Research Centre, Mumbai (India)

2017-04-15

Highlights: • A new DGA-PAMAM-SDB chelating resin has been synthesized for actinide sorption. • Maximum sorption capacities of resin are 682 and 544.2 mg g{sup −1}for U(VI) and Th(IV). • DGA-PAMAM-SDB chelating resin could be regenerated and reused. • DFT calculation of actinides interaction with resin corroborates the experimental. • Resin is effective for sorption of actinides from both aqueous and HNO{sub 3} medium. - Abstract: 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 (> 3 M). The sorption equilibrium could be reached within 60 min, 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{sub 5}-SDB was estimated to be about 682 and 544.2 mg g{sup −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.

Potentials and drawbacks of chelate-enhanced phytoremediation of soils

NARCIS (Netherlands)

Römkens, P.F.A.M.; Bouwman, L.A.; Japenga, J.; Draaisma, C.

2002-01-01

Chelate-enhanced phytoremediation has been proposed as an effective tool for the extraction of heavy metals from soils by plants. However, side-effects related to the addition of chelates, e.g. metal leaching and effects on soil micro-organisms, were usually neglected. Therefore, greenhouse and

Mixed and chelated waste test programs with bitumen solidification

International Nuclear Information System (INIS)

Simpson, S.I.; Morris, M.; Vidal, H.

1988-01-01

This paper presents the results of bitumen solidification tests on mixed wastes and chelated wastes. The French Atomic Energy Commission (CEA) performed demonstration tests on radioactive wastes contaminated with chelating agents for Associated Technologies, Inc. (ATI). The chelated wastes were produced and concentrated by Commonwealth Edison Co. as a result of reactor decontamination at Dresden Nuclear Station, Unit 1. Law Engineering in Charlotte, N. C. produced samples and performed tests on simulated heavy metal laden radioactive waste (mixed) to demonstrate the quality of the bituminous product. The simulation is intended to represent waste produced at Oak Ridge National Labs operated by Martin-Marietta

Thermodynamic analysis on theoretical models of cycle combined heat exchange process: The reversible heat exchange process

International Nuclear Information System (INIS)

Zhang, Chenghu; Li, Yaping

2017-01-01

Concept of reversible heat exchange process as the theoretical model of the cycle combined heat exchanger could be useful to determine thermodynamics characteristics and the limitation values in the isolated heat exchange system. In this study, the classification of the reversible heat exchange processes is presented, and with the numerical method, medium temperature variation tendency and the useful work production and usage in the whole process are investigated by the construction and solution of the mathematical descriptions. Various values of medium inlet temperatures and heat capacity ratio are considered to analyze the effects of process parameters on the outlet temperature lift/drop. The maximum process work transferred from the Carnot cycle region to the reverse cycle region is also researched. Moreover, influence of the separating point between different sub-processes on temperature variation profile and the process work production are analyzed. In addition, the heat-exchange-enhancement-factor is defined to study the enhancement effect of the application of the idealized process in the isolated heat exchange system, and the variation degree of this factor with process parameters change is obtained. The research results of this paper can be a theoretical guidance to construct the cycle combined heat exchange process in the practical system. - Highlights: • A theoretical model of Cycle combined heat exchange process is proposed. • The classification of reversible heat exchange process are presented. • Effects of Inlet temperatures and heat capacity ratio on process are analyzed. • Process work transmission through the whole process is studied. • Heat-exchange-enhancement-factor can be a criteria to express the application effect of the idealized process.

Different photoluminescent properties of binary and ternary europium chelates doped in PMMA

International Nuclear Information System (INIS)

Liu Hongguo; Park, Seongtae; Jang, Kiwan; Zhang Wansong; Seo, Hyo-Jin; Lee, Yong-Ill

2003-01-01

Two kinds of europium-β-diketone chelates, binary Eu(DBM) 3 and ternary Eu(DBM) 3 phen were doped in poly(methyl methacrylate) (PMMA). These chelates show very different photoluminescent (PL) behaviors: the hypersensitive 5 D 0 → 7 F 2 emission bands of Eu(DBM) 3 phen change slightly with the molar ratios, while those of Eu(DBM) 3 change obviously and regularly with the molar ratios. The results of the luminescent lifetimes of 5 D 0 levels show that the binary chelate exists as two kinds of species in the doped systems, and the lifetimes and contents of each species change with the molar ratios, while the ternary chelate exists as one kind of species in the doped systems. X-ray diffraction (XRD) patterns of the binary chelate doped systems give some diffraction peaks that are different from those of pure chelate and change with the molar ratios, indicating new kinds of crystal structures formed, and consequently, the first coordination sphere of Eu 3+ ion changes; while those of the ternary chelate doped systems just show amorphous diffraction halos of the host, indicating that the ternary chelate exist in an amorphous state and disperse well in the host. The FTIR spectra of PMMA also change gradually with increasing the molar ratios of the doped two kinds of chelates, and the XRD patterns show that the amorphous halos of PMMA in the doped systems are different from those of pure PMMA and change with the molar ratios, too, suggesting the interaction between the guest and the host

Phenolic aminocarboxylic acids - new chelating agents for modifying gallium-67 biodistribution

International Nuclear Information System (INIS)

Hunt, F.C.; Maddalena, D.J.

1982-01-01

The chelating agents EDDHA and HBED were synthesised with carboxyl or sulphonyl groups in the phenolic ring to favour urinary excretion on complexing with gallium. Carboxyl EDDMA was administered to tumor-bearing rats, and its concentration in the tumours and other tissues determined by scintigraphic imaging. The chelating agents increase tumour to blood ratios by chelating gallium in vivo. (U.K.)

Antioxidant, Iron-chelating and Anti-glucosidase Activities of Typha ...

African Journals Online (AJOL)

Iron chelating activity was assessed using a ferrozine-based assay. Anti- glucosidase activity was determined using 4-nitrophenyl ... flavonoid (TF) content was determined based an aluminum chloride colorimetric assay [6]. TF content was ..... Dietary iron restriction or iron chelation protects from diabetes and loss of β-cell.

Correction: Large-scale electricity storage utilizing reversible solid oxide cells combined with underground storage of CO2 and CH4

DEFF Research Database (Denmark)

Jensen, Søren Højgaard; Graves, Christopher R.; Mogensen, Mogens Bjerg

2017-01-01

Correction for ‘Large-scale electricity storage utilizing reversible solid oxide cells combined with underground storage of CO2 and CH4’ by S. H. Jensen et al., Energy Environ. Sci., 2015, 8, 2471–2479.......Correction for ‘Large-scale electricity storage utilizing reversible solid oxide cells combined with underground storage of CO2 and CH4’ by S. H. Jensen et al., Energy Environ. Sci., 2015, 8, 2471–2479....

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

Science.gov (United States)

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.

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

Science.gov (United States)

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.

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

Science.gov (United States)

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.

Intrinsic dependence of the magnetic properties of CoFe{sub 2}O{sub 4} nanoparticles prepared via chemical methods with addition of chelating agents

Energy Technology Data Exchange (ETDEWEB)

Mendonça, E.C. [Núcleo de Pós-Graduação em Física, Campus Prof. José Aluísio de Campos, UFS, 49100-000 São Cristóvão, SE (Brazil); Tenório, Mayara A. [Departamento de Física, Campus Prof. Alberto Carvalho, UFS, 49500-000 Itabaiana, SE (Brazil); Mecena, S.G.; Zucolotto, B.; Silva, L.S. [Núcleo de Pós-Graduação em Física, Campus Prof. José Aluísio de Campos, UFS, 49100-000 São Cristóvão, SE (Brazil); Jesus, C.B.R. [Instituto de Física Gleb Wataghin, UNICAMP, C. P. 6165, 13083-970 Campinas, SP (Brazil); Meneses, C.T. [Núcleo de Pós-Graduação em Física, Campus Prof. José Aluísio de Campos, UFS, 49100-000 São Cristóvão, SE (Brazil); and others

2015-12-01

In this work, the effect of addition of different chelating agents on the magnetic properties of cobalt ferrite nanoparticles produced by the combining of both co-precipitation and hydrothermal methods is reported. The Rietveld analyses of X-ray diffraction patterns reveal that our samples are single phase (space group: Fd-3m) with small average sizes. The weight losses observed in the thermogravimetric measurements together with the M×H curves show that the organic contamination coming from chelating agent decomposition can give rise to misinterpretation of the magnetization measurements. Besides, analyses of the zero-field-cooled (ZFC) and field-cooled (FC) magnetization measurements and the M×H curves measured at room temperature allows us to state that both the average blocking temperature and particles size distribution are sensitive to the kind of chelating agent. - Highlights: Superparamagnetism. Chelating agents. Organic contamination.

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

Science.gov (United States)

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

Iron chelators ICL670 and 311 inhibit HIV-1 transcription

International Nuclear Information System (INIS)

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

2007-01-01

HIV-1 replication is induced by an excess of iron and iron chelation by desferrioxamine (DFO) inhibits viral replication by reducing proliferation of infected cells. Treatment of cells with DFO and 2-hydroxy-1-naphthylaldehyde isonicotinoyl hydrazone (311) inhibit expression of proteins that regulate cell-cycle progression, including cycle-dependent kinase 2 (CDK2). Our recent studies showed that CDK2 participates in HIV-1 transcription and viral replication suggesting that inhibition of CDK2 by iron chelators might also affect HIV-1 transcription. Here we evaluated the effect of a clinically approved orally effective iron chelator, 4-[3,5-bis-(hydroxyphenyl)-1,2,4-triazol-1-yl]-benzoic acid (ICL670) and 311 on HIV-1 transcription. Both ICL670 and 311 inhibited Tat-induced HIV-1 transcription in CEM-T cells, 293T and HeLa cells. Neither ICL670 nor 311 induced cytotoxicity at concentrations that inhibited HIV-1 transcription. The chelators decreased cellular activity of CDK2 and reduced HIV-1 Tat phosphorylation by CDK2. Neither ICL670A or 311 decreased CDK9 protein level but significantly reduced association of CDK9 with cyclin T1 and reduced phosphorylation of Ser-2 residues of RNA polymerase II C-terminal domain. In conclusion, our findings add to the evidence that iron chelators can inhibit HIV-1 transcription by deregulating CDK2 and CDK9. Further consideration should be given to the development of iron chelators for future anti-retroviral therapeutics

Bone marrow and chelatable iron in patients with protein energy ...

African Journals Online (AJOL)

chelatable iron is present and is excreted in the urine of children with kwashiorkor ... venous blood sample was drawn for routine biochemical and haematological .... storage.l.1:m In response to chelation, the kwashiorkor children excrete large ...

Selectivity in extraction of copper and indium with chelate extractants

International Nuclear Information System (INIS)

Zivkovic, D.

2003-01-01

Simultaneous extraction of copper and indium with chelate extractants (LIX84 and D2E11PA) was described. Stechiometry of metal-organic complexes examined using the method of equimolar ratios resulted in CuR 2 and InR 3 forms of hydrophobic extracting species. A linear correlation was obtained between logarithm of distribution coefficients and chelate agents and pH, respectively. Selectivity is generally higher with higher concentrations of chelate agents in the organic phase, and is decreased with increase of concentration of hydrogen ions in feeding phase. (Original)

Decorporation approach following rat lung contamination with a moderately soluble compound of plutonium using local and systemic Ca-DTPA combined chelation

International Nuclear Information System (INIS)

Gremy, Olivier; Bruel, Sylvie; Renault, Daniel; Van der Meeren, Anne; Tsapis, Nicolas

2012-01-01

Decorporation efficacy of prompt pulmonary delivery of DTPA dry powder was assessed following lung contamination with plutonium nitrate and compared to an intravenous injection of DTPA solution and a combined administration of both DTPA compounds. In addition, efficacy of a delayed treatment was assessed. In case of either early or late administration, insufflated DTPA was more efficient than intravenously injected DTPA in reducing the plutonium lung burden due to its high local concentration. Prompt treatment with DTPA powder was also more effective in limiting extrapulmonary deposits by removing the early transportable fraction of plutonium from lungs prior its absorption into blood. Translocation of DTPA from lungs to blood may also contribute to the decrease in extrapulmonary retention, as shown by reduced liver deposit after delayed pulmonary administration of DTPA. Efficacy of DTPA dry powder was further increased by the combined intravenous administration of DTPA solution for reducing extrapulmonary deposits of plutonium and promoting its urinary excretion. According to our results, the most effective treatment protocol for plutonium decorporation was the early pulmonary delivery of DTPA powder supplemented by an intravenous injection of DTPA solution. Following inhalation of plutonium as nitrate chemical form, this combined chelation therapy should provide a more effective method of treatment than conventional intravenous injection alone. At later stages following lung contamination, pulmonary administration of DTPA should also be considered as the treatment of choice for decreasing the lung burden. (authors)

EDTA chelation therapy for cardiovascular disease: a systematic review

Directory of Open Access Journals (Sweden)

Wu Ping

2005-11-01

Full Text Available Abstract Background Numerous practitioners of both conventional and complementary and alternative medicine throughout North America and Europe claim that chelation therapy with EDTA is an effective means to both control and treat cardiovascular disease. These claims are controversial, and several randomized controlled trials have been completed dealing with this topic. To address this issue we conducted a systematic review to evaluate the best available evidence for the use of EDTA chelation therapy in the treatment of cardiovascular disease. Methods We conducted a systematic review of 7 databases from inception to May 2005. Hand searches were conducted in review articles and in any of the trials found. Experts in the field were contacted and registries of clinical trials were searched for unpublished data. To be included in the final systematic review, the studies had to be randomized controlled clinical trials. Results A total of seven articles were found assessing EDTA chelation for the treatment of cardiovascular disease. Two of these articles were subgroup analyses of one RCT that looked at different clinical outcomes. Of the remaining five studies, two smaller studies found a beneficial effect whereas the other three exhibited no benefit for cardiovascular disease from the use of EDTA chelation therapy. Adverse effects were rare but those of note included a few cases of hypocalcemia and a single case of increased creatinine in a patient on the EDTA intervention. Conclusion The best available evidence does not support the therapeutic use of EDTA chelation therapy in the treatment of cardiovascular disease. Although not considered to be a highly invasive or harmful therapy, it is possible that the use of EDTA chelation therapy in lieu of proven therapy may result in causing indirect harm to the patient.

Chelation Treatment for Autism Spectrum Disorders: A Systematic Review

Science.gov (United States)

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.

Science.gov (United States)

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.

Characterization of amorphous yttria layers deposited by aqueous solutions of Y-chelate alkoxides complex

Energy Technology Data Exchange (ETDEWEB)

Kim, Young-Soon, E-mail: kyscjb@i-sunam.com; Lee, Yu-Ri; Kim, Byeong-Joo; Lee, Jae-Hun; Moon, Seung-Hyun; Lee, Hunju

2015-01-15

Highlights: • Economical method for crack-free amorphous yttria layer deposition by dip coating. • Simpler process for planar yttria film as a diffusion barrier and nucleation layer. • Easy control over the film properties with better characteristics. • Easy control over the thickness of the deposited films. • A feasible process that can be easily adopted by HTSCC industries. - Abstract: Crack-free amorphous yttria layers were deposited by dip coating in solutions of different Y-chelate alkoxides complex. Three Y-chelate solutions of different concentrations were prepared using yttrium acetate tetrahydrate, yttrium stearic acid as Y source materials. PEG, diethanolamine were used as chelating agents, while ethanol, methanol and tetradecane were used as solvent. Three different combinations of chelating and solvents were used to prepare solutions for Y{sub 2}O{sub 3} dip coating on SUS, electropolished and non-electropolished Hastelloy C-276 substrates. The thickness of the films was varied by changing the number of dipping cycles. At an optimized condition, the substrate surface roughness (rms) value was reduced from ∼50 nm to ∼1 nm over a 10 × 10 μm{sup 2} area. After Y{sub 2}O{sub 3} deposition, MgO was deposited using ion-beam assisted deposition (IBAD), then LaMnO{sub 3} (LMO) was deposited using sputtering and GdBCO was deposited using reactive co-evaporation by deposition and reaction (RCE-DR). Detailed X-ray study indicates that LMO/MgO/Y{sub 2}O{sub 3} and GdBCO/LMO/MgO/Y{sub 2}O{sub 3} stack films have good out-of-plane and in-plane textures with strong c-axis alignment. The critical current (Ic) of GdBCO/LMO/MgO/Y{sub 2}O{sub 3} multilayer structure varied from 190 to 420 A/cm with different solutions, when measured at 77 K. These results demonstrated that amorphous yttria can be easily deposited by dip coating using Y-chelates complex as a diffusion barrier and nucleation layer.

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

OpenAIRE

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

2016-01-01

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

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

Directory of Open Access Journals (Sweden)

Gloria Miller

2008-12-01

with the metal or distilled deionized water were applied to the root zones. Plants were harvested at 6 days after chelate addition to coincide with the duration of maximum metal solubility previously determined in this study. Results of the greenhouse experiment showed that coffeeweed was relatively tolerant to moderate levels of Pb and chelates as shown by very slight reductions in root and no discernable effects on shoot biomass. Root Pb concentrations increased with increasing levels of soil-applied Pb. Further increases in root Pb concentrations were attributed to chelate amendments. In the absence of chelates, translocation of Pb from roots to shoots was minimal. However, translocation dramatically increased in treatments with EDTA alone or in combination with HAc. Overall, the results of this study indicated that depending on the nature and type of Pb-contaminated soil being remediated, the bioavailability and uptake of Pb by coffeeweed can be enhanced by amending the soil with chelates especially after the plants have reached maximum biomass.

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

International Nuclear Information System (INIS)

Paine, R.T.

2000-01-01

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

Click-to-Chelate: Development of Technetium and Rhenium-Tricarbonyl Labeled Radiopharmaceuticals

Directory of Open Access Journals (Sweden)

Thomas L. Mindt

2013-03-01

Full Text Available The Click-to-Chelate approach is a highly efficient strategy for the radiolabeling of molecules of medicinal interest with technetium and rhenium-tricarbonyl cores. Reaction of azide-functionalized molecules with alkyne prochelators by the Cu(I-catalyzed azide-alkyne cycloaddition (CuAAC; click reaction enables the simultaneous synthesis and conjugation of tridentate chelating systems for the stable complexation of the radiometals. In many cases, the functionalization of (biomolecules with the ligand system and radiolabeling can be achieved by convenient one-pot procedures. Since its first report in 2006, Click-to-Chelate has been applied to the development of numerous novel radiotracers with promising potential for translation into the clinic. This review summarizes the use of the Click-to-Chelate approach in radiopharmaceutical sciences and provides a perspective for future applications.

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

Science.gov (United States)

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.

Heavy metal displacement in chelate-irrigated soil during phytoremediation

Science.gov (United States)

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.

Characterization of commercial iron chelates and their behavior in an alkaline and calcareous soil.

Science.gov (United States)

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.

Science.gov (United States)

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.

The iron chelator deferasirox protects mice from mucormycosis through iron starvation

Science.gov (United States)

Ibrahim, Ashraf S.; Gebermariam, Teclegiorgis; Fu, Yue; Lin,, Lin; Husseiny, Mohamed I.; French, Samuel W.; Schwartz, Julie; Skory, Christopher D.; Edwards, John E.; Spellberg, Brad J.

2007-01-01

Mucormycosis causes mortality in at least 50% of cases despite current first-line therapies. Clinical and animal data indicate that the presence of elevated available serum iron predisposes the host to mucormycosis. Here we demonstrate that deferasirox, an iron chelator recently approved for use in humans by the US FDA, is a highly effective treatment for mucormycosis. Deferasirox effectively chelated iron from Rhizopus oryzae and demonstrated cidal activity in vitro against 28 of 29 clinical isolates of Mucorales at concentrations well below clinically achievable serum levels. When administered to diabetic ketoacidotic or neutropenic mice with mucormycosis, deferasirox significantly improved survival and decreased tissue fungal burden, with an efficacy similar to that of liposomal amphotericin B. Deferasirox treatment also enhanced the host inflammatory response to mucormycosis. Most importantly, deferasirox synergistically improved survival and reduced tissue fungal burden when combined with liposomal amphotericin B. These data support clinical investigation of adjunctive deferasirox therapy to improve the poor outcomes of mucormycosis with current therapy. As iron availability is integral to the pathogenesis of other infections (e.g., tuberculosis, malaria), broader investigation of deferasirox as an antiinfective treatment is warranted. PMID:17786247

The preparation and characterization of novel human-like collagen metal chelates

Energy Technology Data Exchange (ETDEWEB)

Zhu, Chenhui; Sun, Yan [Shaanxi Key Laboratory of Degradable Biomedical Materials, School of Chemical Engineering Northwest University, Xi' an 710069 (China); Shaanxi R and D Center of Biomaterials and Fermentation Engineering, Xi' an 710069 (China); Wang, Yaoyu [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of the Ministry of Education, Xi' an 710069 (China); Luo, Yane, E-mail: luoyane@nwu.edu.cn [Shaanxi Key Laboratory of Degradable Biomedical Materials, School of Chemical Engineering Northwest University, Xi' an 710069 (China); Shaanxi R and D Center of Biomaterials and Fermentation Engineering, Xi' an 710069 (China); Fan, Daidi, E-mail: fandaidi@nwu.edu.cn [Shaanxi Key Laboratory of Degradable Biomedical Materials, School of Chemical Engineering Northwest University, Xi' an 710069 (China); Shaanxi R and D Center of Biomaterials and Fermentation Engineering, Xi' an 710069 (China)

2013-07-01

In order to develop the nutritional trace elements which could be absorbed and utilized effectively, protein chelates were adopted. Calcium, copper and manganese were considered based on their physiological functions, and the new chelates of HLC-Ca, HLC-Cu and HLC-Mn were formed in MOPS or MES buffer and purified by gel chromatography, and then freeze-dried. And they were detected and analyzed by atomic absorption spectrophotometry, ultraviolet–visible absorption (UV–vis) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, fluorescence quenching method, circular dichroism (CD) and differential scanning calorimetry (DSC). The results showed that some chemical reactions happened between HLC and the three metal ions to form new chemical compounds. The thermodynamic parameters, ∆H, ∆G and ∆S, showed that the chelation process between HLC and metal ions was performed spontaneously. Fluorescence quenching spectra of HLC indicated that the quenching mechanism was static in nature. According to the data of DSC, the new chelates were more stable than the free HLC. And HLC-metal complex was non-toxic to the BHK21 cell through MTT assay. - Highlights: ► HLC-Ca, HLC-Cu and HLC-Mn were new chemical compounds and different to free HLC. ► Possible sites for Ca{sup 2+}, Cu{sup 2+} and Mn{sup 2+} to bind with HLC were presented. ► The chelation process between HLC and metal ions was performed spontaneously. ► The thermodynamic stability of the new chelates was higher than that of free HLC.

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

Science.gov (United States)

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.

Chelation therapy to treat atherosclerosis, particularly in diabetes: is it time to reconsider?

Science.gov (United States)

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.

Decorporation of metal ions by chelating agents

International Nuclear Information System (INIS)

Koenig, T.

1978-01-01

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

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

Science.gov (United States)

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.

Studies of the competition for thorium ion between chelating agents and bovine serum albumin

International Nuclear Information System (INIS)

Luo Meichu; Zhang Meizhen; Sun Meizhen; Chen Shijie

1995-01-01

Fourteen chelation agents (polyaminopolcarboxylate type--TTHA, DTPA, EDTA; phenolicpolycarboxylate type--811, 8102, 7601, 7602, 7603, 7616, 7711, 7724, 7803, 7804, 8307) were studied their competitive ability to mobilize the thorium with bovine serum albumin (BSA). The experimental results showed that the competitive ability of TTHA, 8102, 811 to chelate Thorium with BSA were the strongest, and EDTA was the worst in all chelating agents. The measured order of the competitive ability of chelators is basically consistent with animal experimental results in vivo. The parameter F is defined as the competitive ability of chelators. F is taken as a screening criterion for de-corporate thorium which is simple, quick and effective method in vitro

Fluoride ion recognition by chelating and cationic boranes.

Science.gov (United States)

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

Evaluation of macrocyclic hydroxyisophthalamide ligands as chelators for zirconium-89.

Science.gov (United States)

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.

Evaluation of macrocyclic hydroxyisophthalamide ligands as chelators for zirconium-89.

Directory of Open Access Journals (Sweden)

Nikunj B Bhatt

Full Text Available 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.

Chelates for Micronutrient Nutrition among Crops

Indian Academy of Sciences (India)

years, it has been recognised that compounds containing che- lated metals could .... when using small amounts and no build up of harmful levels. ... degradation of iron chelates. .... down by soil microorganisms into much smaller units for ab-.

Metal chelate conjugated monoclonal antibodies, wherein the metal is an α emitter

International Nuclear Information System (INIS)

Gansow, O.A.; Strand, M.

1984-01-01

Methods of manufacturing and purifying metal chelate conjugated monoclonal antibodies are described, wherein the chelated metal emits alpha radiation. The conjugates are suited for therapeutic uses being substantially free of nonchelated radiometal. (author)

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

Directory of Open Access Journals (Sweden)

Saibo Huang

2015-12-01

Full Text Available 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.

Beneficiation of a Sedimentary Phosphate Ore by a Combination of Spiral Gravity and Direct-Reverse Flotation

Directory of Open Access Journals (Sweden)

Xin Liu

2016-04-01

Full Text Available In China, direct-reverse flotation is proved to be applicable to most phosphate ores. However, because the ratio of froth product is generally high, current direct-reverse technology faces challenges in terms of high reagent consumptions and cost. A new gravity and flotation combined process has been developed for the recovery of collophanite from sedimentary phosphate ore from the beneficiation plant of Hubei, China. In this process, 53% of the collophanite was firstly recovered by gravity separation, reducing the mass flow to direct flotation. The gravity tailing was the feed for the direct flotation. The flotation concentrate, mixed with gravity concentrate, was then subjected to reverse flotation. A final concentrate with a grade of 30.41% P2O5 at a recovery of 91.5% was produced from the feed analyzing 21.55% P2O5. Compared to the conventional direct-reverse flotation 86.1% recovery at 31.69% P2O5, it was found that pre-recovery of collophanite by spiral separation could significantly reduce the flotation reagent consumption and lead to improved overall collophanite recovery. The benefits of the new process in terms of cost savings were also discussed.

Immobilisation of impala (Aepyceros melampus with a ketamine hydrochloride / medetomidine hydrochloride combination, and reversal with atipamezole hydrochloride

Directory of Open Access Journals (Sweden)

M. Bush

2004-06-01

Full Text Available A combination of medetomidine hydrochloride (medetomidine and ketamine hydrochloride (ketamine was evaluated in 16 boma-confined and 19 free-ranging impalas (Aepyceros melampus to develop a non-opiate immobilisation protocol. In free-ranging impala a dose of 220 + 34 mg/kg medetomidine and 4.4 + 0.7 mg/kg ketamine combined with 7500 IU of hyaluronidase induced recumbency within 4.5+1.5 min, with good muscle relaxation, a stable heart rate and blood pH. PaCO2 was maintained within acceptable ranges. The animals were hypoxic with reduced oxygen saturation and low PaO2 in the presence of an elevated respiration rate, therefore methods for respiratory support are indicated. The depth of sedation was adequate for minor manipulations but additional anaesthesia is indicated for painful manipulations. Immobilisation was reversed by 467 + 108 mg/kg atipamezole hydrochloride (atipamezole intramuscularly, but re-sedation was observed several hours later, possibly due to a low atipamezole:medetomidine ratio of 2:1. Therefore, this immobilisation and reversal protocol would subject impalas to possible predation or conspecific aggression following reversal if they were released into the wild. If the protocol is used on free-ranging impala, an atipamezole:medetomidine ratio of 5:1 should probably be used to prevent re-sedation.

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

International Nuclear Information System (INIS)

Serne, R.J.; Felmy, A.R.; Cantrell, K.J.; Krupka, K.M.; Campbell, J.A.; Bolton, H. Jr.; Fredrickson, J.K.

1996-03-01

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

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

Energy Technology Data Exchange (ETDEWEB)

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

1996-03-01

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

Inositol hexa-phosphate: a potential chelating agent for uranium

International Nuclear Information System (INIS)

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

2007-01-01

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

A functional language for describing reversible logic

DEFF Research Database (Denmark)

Thomsen, Michael Kirkedal

2012-01-01

Reversible logic is a computational model where all gates are logically reversible and combined in circuits such that no values are lost or duplicated. This paper presents a novel functional language that is designed to describe only reversible logic circuits. The language includes high....... Reversibility of descriptions is guaranteed with a type system based on linear types. The language is applied to three examples of reversible computations (ALU, linear cosine transformation, and binary adder). The paper also outlines a design flow that ensures garbage- free translation to reversible logic...... circuits. The flow relies on a reversible combinator language as an intermediate language....

On-load chelating agent treatments for conventional and nuclear power stations

International Nuclear Information System (INIS)

Turner, D.J.

1978-01-01

The paper is concerned with the application of on-load chelating agent treatments to those types of water circuit for which they are not currently available: high pressure drum boilers, sub-critical once-through boilers and water reactors. An attempt was made to see whether the most thermally stable types of chelating agent are likely to be sufficiently strong chelating agents either to dissolve established Fe 3 O 4 deposits or to prevent their precipitation from solution. It seems likely that they are strong enough to prevent Fe 3 O 4 depositing in a once-through boiler, through some may require that mildly reducing conditions are maintained. They would not be effective in a high pressure drum boiler (at 350 0 C) unless much more strongly reducing conditions could be maintained. For such boilers it would probably be better to seek multidentate ligands of less than maximum thermal stability. There are some indications that chelating agents based on carbon chains are more stable than NTA or EDTA so that citric acid or some of the unidentified chelating agents recently found to be produced radiolytically may have potential in the treatment of high pressure drum boilers. The prospects for periodic full-load cleaning seem less good for both types of boiler. There may also be a role for radiolytically produced chelating agents in alleviating some of the problems caused by the deposition of radioactive corrosion products in water reactor circuits. The chances for successful development fall from quite good to very low down the series SGHWR moderator circuit, PWR primary circuit, ammonia dosed BWR, neutral chemistry BWR (including SGHWR). (author)

Improved paramagnetic chelate for molecular imaging with MRI

International Nuclear Information System (INIS)

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

2005-01-01

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

Improved paramagnetic chelate for molecular imaging with MRI

Science.gov (United States)

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.

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

Science.gov (United States)

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.

Chelator induced phytoextraction and in situ soil washing of Cu

International Nuclear Information System (INIS)

Kos, Bostjan; Lestan, Domen

2004-01-01

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

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

Science.gov (United States)

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

Metal Chelation as a Powerful Strategy to Probe Cellular Circuitry Governing Fungal Drug Resistance and Morphogenesis.

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Elizabeth J Polvi

2016-10-01

Full Text Available Fungal pathogens have evolved diverse strategies to sense host-relevant cues and coordinate cellular responses, which enable virulence and drug resistance. Defining circuitry controlling these traits opens new opportunities for chemical diversity in therapeutics, as the cognate inhibitors are rarely explored by conventional screening approaches. This has great potential to address the pressing need for new therapeutic strategies for invasive fungal infections, which have a staggering impact on human health. To explore this approach, we focused on a leading human fungal pathogen, Candida albicans, and screened 1,280 pharmacologically active compounds to identify those that potentiate the activity of echinocandins, which are front-line therapeutics that target fungal cell wall synthesis. We identified 19 compounds that enhance activity of the echinocandin caspofungin against an echinocandin-resistant clinical isolate, with the broad-spectrum chelator DTPA demonstrating the greatest synergistic activity. We found that DTPA increases susceptibility to echinocandins via chelation of magnesium. Whole genome sequencing of mutants resistant to the combination of DTPA and caspofungin identified mutations in the histidine kinase gene NIK1 that confer resistance to the combination. Functional analyses demonstrated that DTPA activates the mitogen-activated protein kinase Hog1, and that NIK1 mutations block Hog1 activation in response to both caspofungin and DTPA. The combination has therapeutic relevance as DTPA enhanced the efficacy of caspofungin in a mouse model of echinocandin-resistant candidiasis. We found that DTPA not only reduces drug resistance but also modulates morphogenesis, a key virulence trait that is normally regulated by environmental cues. DTPA induced filamentation via depletion of zinc, in a manner that is contingent upon Ras1-PKA signaling, as well as the transcription factors Brg1 and Rob1. Thus, we establish a new mechanism by which

Albumin microspheres labeled with Ga-67 by chelation: concise communication

International Nuclear Information System (INIS)

Hnatowich, D.J.; Schlegel, P.

1981-01-01

Albumin microspheres have been synthesized with EDTA and DTPA chelating groups covalently bound to their surface. The microspheres may be labeled with Ga-67 at high yield (97 +- 2%) by transcomplexation from a 0.1 M Ga-67 acetate solution. With EDTA microspheres the resulting label dissociates only slightly after 24 hr in 50% plasma at 37 0 C, whereas with DTPA microspheres the label shows no detectable dissociation over this period. By contrast, microspheres without chelating groups lose their label virtually completely under these conditions. Following intravenous administration of sized Ga-67 DTPA microspheres in mice, about (84 +- 16)% of the activity localizes in the lungs at 5 min, with (60 +- 7)% remaining after 2 h. Since labeling is by chelation, the microspheres may also be tagged with other metallic radionuclides

Early orthopedic correction of skeletal Class III malocclusion using combined reverse twin block and face mask therapy

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Vinay Kumar Chugh

2015-01-01

Full Text Available A 6-year 8-month-old girl presented with a moderate Class III malocclusion characterized by mid-face deficiency and an anterior cross bite. In the first phase, the patient was treated with combination of reverse twin block and facemask therapy. In phase two, fixed appliances were placed in the permanent dentition. The post treatment results were good and a favorable growth tendency could be observed. The correction of the Class III malocclusion occurred by a combination of skeletal and dental improvements. This report shows successful correction of skeletal Class III malocclusion in the early transitional dentition using combination therapy.

Packet reversed packet combining scheme

International Nuclear Information System (INIS)

Bhunia, C.T.

2006-07-01

The packet combining scheme is a well defined simple error correction scheme with erroneous copies at the receiver. It offers higher throughput combined with ARQ protocols in networks than that of basic ARQ protocols. But packet combining scheme fails to correct errors when the errors occur in the same bit locations of two erroneous copies. In the present work, we propose a scheme that will correct error if the errors occur at the same bit location of the erroneous copies. The proposed scheme when combined with ARQ protocol will offer higher throughput. (author)

Selective chelation-supercritical fluid extraction of metal ions from waste materials

International Nuclear Information System (INIS)

Wai, C.N.; Laintz, K.E.; Yonker, C.R.

1993-01-01

The removal of toxic organics, metals, and radioisotopes from solids or liquids is a major concern in the treatment of industrial and nuclear wastes. For this reason, developing methods for selective separation of toxic metals and radioactive materials from solutions of complex matrix is an important problem in environmental research. Recent developments indicate supercritical fluids are good solvents for organic compounds. Many gases become supercritical fluids under moderate temperatures and pressures. For example, the critical temperature and pressure of carbon dioxide are 31 degrees C and 73 atm, respectively. The high diffusivity, low viscosity, and T-P dependence of solvent strength are some attractive properties of supercritical fluid extraction (SFE). Since CO 2 offers the additional benefits of stability and non-toxicity, the SFE technique avoids generation of organic liquid waste and exposure of personnel to toxic solvents. While direct extraction of metal ions by supercritical fluids is highly inefficient, these ions when complexed with organic ligands become quite soluble in supercritical fluids. Specific ligands can be used to achieve selective extraction of metal ions in this process. After SFE, the fluid phase can be depressurized for precipitation of the metal chelates and recycled. The ligand can also be regenerated for repeated use. The success of this selective chelation-supercritical fluid extraction (SC-SFE) process depends on a number of factors including the efficiencies of the selective chelating agents, solubilities of metal chelates in supercritical fluids, rate of extraction, ease of regeneration of the ligands, etc. In this report, the authors present recent results on the studies of the solubilities of metal chelates in supercritical CO 2 , experimental ions from aqueous solution, and the development of selective chelating agents (ionizable crown ethers) for the extraction of lanthanides and actinides

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

Science.gov (United States)

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.

Science.gov (United States)

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

Thermometric studies on the Fe(III)-EDTA chelate.

Science.gov (United States)

Dot, K

1978-02-01

A DeltaH of -11.5 +/- 0.5 kJ/mole has been determined for the formation of the Fe(III)-EDTA chelate at 25.0 degrees and mu = 0.1(= [HClO(4)] + [NaClO(4)]) by a direct thermometric titration procedure. The entropy change, DeltaS, has been calculated to be 440 J.mole(-1) .deg(-1) by combining the result of the heat measurements with the free energy change obtained from the stability constant previously determined. A relationship between the DeltaS values and the standard partial molal entropies of the tervalent metal ions is discussed. In addition, conditions for the thermometric titration of Fe(III) with NA(4)EDTA at room temperature have been investigated. Iron(III) can be determined in the presence of fairly large amounts of phosphate, Cr(III), Mn(II) and Al(III).

Antimalarial iron chelator, FBS0701, shows asexual and gametocyte Plasmodium falciparum activity and single oral dose cure in a murine malaria model.

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Patricia Ferrer

Full Text Available Iron chelators for the treatment of malaria have proven therapeutic activity in vitro and in vivo in both humans and mice, but their clinical use is limited by the unsuitable absorption and pharmacokinetic properties of the few available iron chelators. FBS0701, (S3"-(HO-desazadesferrithiocin-polyether [DADFT-PE], is an oral iron chelator currently in Phase 2 human studies for the treatment of transfusional iron overload. The drug has very favorable absorption and pharmacokinetic properties allowing for once-daily use to deplete circulating free iron with human plasma concentrations in the high µM range. Here we show that FBS0701 has inhibition concentration 50% (IC(50 of 6 µM for Plasmodium falciparum in contrast to the IC(50 for deferiprone and deferoxamine at 15 and 30 µM respectively. In combination, FBS0701 interfered with artemisinin parasite inhibition and was additive with chloroquine or quinine parasite inhibition. FBS0701 killed early stage P. falciparum gametocytes. In the P. berghei Thompson suppression test, a single dose of 100 mg/kg reduced day three parasitemia and prolonged survival, but did not cure mice. Treatment with a single oral dose of 100 mg/kg one day after infection with 10 million lethal P. yoelii 17XL cured all the mice. Pretreatment of mice with a single oral dose of FBS0701 seven days or one day before resulted in the cure of some mice. Plasma exposures and other pharmacokinetics parameters in mice of the 100 mg/kg dose are similar to a 3 mg/kg dose in humans. In conclusion, FBS0701 demonstrates a single oral dose cure of the lethal P. yoelii model. Significantly, this effect persists after the chelator has cleared from plasma. FBS0701 was demonstrated to remove labile iron from erythrocytes as well as enter erythrocytes to chelate iron. FBS0701 may find clinically utility as monotherapy, a malarial prophylactic or, more likely, in combination with other antimalarials.

Which psychosocial factors are related to chelation adherence in thalassemia? A systematic review.

Science.gov (United States)

Evangeli, Michael; Mughal, Kulsoom; Porter, John B

2010-06-01

Good adherence to iron chelation therapy in thalassemia is crucial. Although there is evidence that adherence is related to regimen factors, there has been less emphasis on the relationship between psychosocial (psychological, demographic and social) factors and adherence. We present a systematic review of psychosocial correlates of chelation adherence in thalassemia. Nine studies met the inclusion criteria. Information was extracted regarding the study characteristics and the relationship between psychosocial factors and chelation adherence. Methodological quality was rated. The studies took place in a range of countries, were mostly cross sectional in design, and examined adherence to deferoxamine (DFO) only. Sample sizes ranged from 15 to 1573. A variety of psychosocial variables were examined. Definitions of adherence varied between studies and non adherence rates were also variable (9 to 66%). Older age was consistently associated with lower levels of chelation adherence. There were few other consistent findings. The methodological quality of studies was variable. There is a need for more methodologically sophisticated and theoretically informed studies on psychosocial correlates of chelation adherence. We offer specific suggestions.

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

Science.gov (United States)

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.

A study on the adsorption and subsurface transport of radioactive solutes in the presence of chelating agents

International Nuclear Information System (INIS)

Baik, Min Hoon

1994-02-01

In this study, adsorption and transport models were developed to analyze the effect of chelating agents on the adsorption and subsurface transport of radioactive solutes. The effect of chelating agents on the adsorption of radioactive solutes was analyzed by developing an adsorption model based upon the extended concept of distribution coefficient reflecting the presence of chelating agents. Also, a batch adsorption experiment was conducted in order to validate the developed adsorption model and to investigate the effect of chelating agent on the adsorption of radioactive metal solutes. In this experiment, a Cobalt(II)/EDTA/Bentonite system was considered as a representative chelation/adsorption system. It was found from the results that the presence of chelating agents significantly reduced the adsorbing capacity of geologic media such as clay minerals and soils. Thus it was concluded that the presence of chelating agents even in a small amount could contribute to the mobilization of radioactive solutes from radioactive waste burial sites by reducing the adsorbing capacity of geologic media. The effect of chelating agents on the transport of radioactive solutes in subsurface porous media was analyzed by formulating an advective-dispersive transport model which incorporated chelate formation, adsorption, decay, and degradations and by introducing the concept of a tenad. Particularly the governing equation for the tenad of radioactive solutes, M, was presented as a linear partial differential form by introducing the extended distribution coefficient, K D . The calculated results from the model showed that the transport rate of the chelated radionuclides was much greater than that of the free ionic radionuclides. This much faster transport of the chelated radionuclides was found to be due to the lower retardation factor of the chelated radionuclides than the free ionic radionuclides. The effect of parameters on the transport of radioactive solutes was also analyzed

Studies on effect of Microbial Iron Chelators on Candida Albican

International Nuclear Information System (INIS)

Rehmani, Fouzia S.; Milicent, S.; Zaheer-Uddin

2005-01-01

Iron is an essential for the life of all microbe cells. It generally exists in the oxidized form Fe(III). Even under anaerobic reducing condition the metal appear to be taken up as Fe(III). Thus free-living microorganisms require specific and effective ferric ion transport system to cope with low availability of the metal. In iron deficient environment they produce a low molecular weight specific chelators called siderphores or microbial iron chelators. Siderphores compete for limited supplied of iron. These compounds came out of the cell but can not re-enter without iron due to high affinity of these siderphores often have more than one catechol/hydroxamate functions and are multidentate (usually hexadentate ligands). The aim of the present research is to check the effect of iron chelators, namely gallic acid and salisyl hydroxamate on the growth of Candida albican in vitro. C. albican is the opportunistic paltogen present as the normal flora inside human body. In vivo the growth of C. albican is distributed by the use of antibiotics and immuno suppressers. In cases of iron over-dosage in human being, the patients are treated with certain a-iron chelators. Hence an attempt is made to notice the effect that might be inhibition or enhancement of the organism in vitro. (author)

Design, synthesis, and evaluation of polyhydroxamate chelators for selective complexation of actinides

International Nuclear Information System (INIS)

Gopalan, A.; Jacobs, H.; Koshti, N.; Stark, P.; Huber, V.; Dasaradhi, L.; Caswell, W.; Smith, P.; Jarvinen, G.

1995-01-01

Specific chelating polymers targeted for actinides have much relevance to problems involving remediation of nuclear waste. Goal is to develop polymer supported, ion specific extraction systems for removing actinides and other hazardous metal ions from wastewaters. This is part of an effort to develop chelators for removing actinide ions such as Pu from soils and waste streams. Selected ligands are being attached to polymeric backbones to create novel chelating polymers. These polymers and other water soluble and insoluble polymers have been synthesized and are being evaluated for ability to selectively remove target metal ions from process waste streams

Synthesis of novel bifunctional chelators and their use in preparing monoclonal antibody conjugates for tumor targeting

International Nuclear Information System (INIS)

Westerberg, D.A.; Carney, P.L.; Rogers, P.E.; Kline, S.J.; Johnson, D.K.

1989-01-01

Bifunctional derivatives of the chelating agents ethylenediaminetetraacetic acid and diethylenetriaminepentaacetic acid, in which a p-isothiocyanatobenzyl moiety is attached at the methylene carbon atom of one carboxymethyl arm, was synthesized by reductive alkylation of the relevant polyamine with (p-nitrophenyl)pyruvic acid followed by carboxymethylation, reduction of the nitro group, and reaction with thiophosgene. The resulting isothiocyanate derivatives reacted with monoclonal antibody B72.3 to give antibody-chelator conjugates containing 3 mol of chelator per mole of immunoglobulin, without significant loss of immunological activity. Such conjugates, labeled with the radioisotopic metal indium-111, selectively bound a human colorectal carcinoma implanted in nude mice when given intravenously. Uptake into normal tissues was comparable to or lower than that reported for analogous conjugates with known bifunctional chelators. It is concluded that substitution with a protein reactive group at this position in polyaminopolycarboxylate chelators does not alter the chelating properties of these molecules to a sufficient extent to adversely affect biodistribution and thus provides a general method for the synthesis of such chelators

Metal-chelating compounds produced by ectomycorrhizal fungi collected from pine plantations.

Science.gov (United States)

Machuca, A; Pereira, G; Aguiar, A; Milagres, A M F

2007-01-01

To investigate the in vitro production of metal-chelating compounds by ectomycorrhizal fungi collected from pine plantations in southern Chile. Scleroderma verrucosum, Suillus luteus and two isolates of Rhizopogon luteolus were grown in solid and liquid modified Melin-Norkans (MMN) media with and without iron addition and the production of iron-chelating compounds was determined by Chrome Azurol S (CAS) assay. The presence of hydroxamate and catecholate-type compounds and organic acids was also investigated in liquid medium. All isolates produced iron-chelating compounds as detected by CAS assay, and catecholates, hydroxamates as well as oxalic, citric and succinic acids were also detected in all fungal cultures. Scleroderma verrucosum produced the greatest amounts of catecholates and hydroxamates whereas the highest amounts of organic acids were detected in S. luteus. Nevertheless, the highest catecholate, hydroxamate and organic acid concentrations did not correlate with the highest CAS reaction which was observed in R. luteolus (Yum isolate). Ectomycorrhizal fungi produced a variety of metal-chelating compounds when grown in liquid MMN medium. However, the addition of iron to all fungi cultures reduced the CAS reaction, hydroxamate and organic acid concentrations. Catecholate production was affected differently by iron, depending on the fungal isolate. The ectomycorrhizal fungi described in this study have never been reported to produce metal-chelating compound production. Moreover, apart from some wood-rotting fungi, this is the first evidence of the presence of catecholates in R. luteolus, S. luteus and S. verrucosum cultures.

Effect of other metals on iron bioavailability in presence of a selective chelator

International Nuclear Information System (INIS)

Rehman, F.S.

1995-01-01

Iron (III) is generally very easily chelated by a number of chelators in the biological environment, either supplied by food or already present there. One of the these chelator is gallic acid. The stability constants of the complexes formed between gallic acid and other trace metals have been determined by a potentiometric method. The data obtained was computed with the help of computer program B est . The resulted Beta values were compared with already known values of iron gallic acid complexes. (author)

Chelation therapy in intoxications with mercury, lead and copper

DEFF Research Database (Denmark)

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

2015-01-01

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

Metal chelators and neurotoxicity: lead, mercury, and arsenic.

Science.gov (United States)

Bjørklund, Geir; Mutter, Joachim; Aaseth, Jan

2017-12-01

This article reviews the clinical use of the metal chelators sodium 2,3-dimercapto-1-propanesulfonate (DMPS), meso-2,3-dimercaptosuccinic acid (DMSA), and calcium disodium edetate (CaEDTA, calcium EDTA) in overexposure and poisonings with salts of lead (Pb), mercury (Hg), and arsenic (As). DMSA has considerably lower toxicity than the classic heavy metal antagonist BAL (2,3-dimercaptopropanol) and is also less toxic than DMPS. Because of its adverse effects, CaEDTA should be replaced by DMSA as the antidote of choice in treating moderate Pb poisoning. Combination therapy with BAL and CaEDTA was previously recommended in cases of severe acute Pb poisoning with encephalopathy. We suggest that BAL in such cases acted as a shuttling Pb transporter from the intra- to the extracellular space. The present paper discusses if a combination of the extracellularly distributed DMSA with the ionophore, Monensin may provide a less toxic combination for Pb mobilization by increasing both the efflux of intracellularly deposited Pb and the urinary Pb excretion. Anyhow, oral therapy with DMSA should be continued with several intermittent courses. DMPS and DMSA are also promising antidotes in Hg poisoning, whereas DMPS seems to be a more efficient agent against As poisoning. However, new insight indicates that a combination of low-dosed BAL plus DMPS could be a preferred antidotal therapy to obtain mobilization of the intracerebral deposits into the circulation for subsequent rapid urinary excretion.

Toxicity of copper chelates of azomethines and amino acids for Chlorella pyrenoidosa

Energy Technology Data Exchange (ETDEWEB)

Barashkov, G.K.; Rukhadze, E.G.; Talyzenkova, G.P.

1979-01-01

The authors have attempted to assess the toxicity of copper-containing compounds from the point of view of their interrelationship with the structural characteristics of the chelate compound and the structure of the ligand. The copper chelates of the azomethines tested may be provisionally divided into three types: A - complexes with N-alkly-azomethines; B - complexes with N-aryl-azomethines; C - binuclear complexes. Consideration was also given to chelates with aromatic and heterocyclic amino acids and to heteroligand chelates in which the copper atom coordinates azomethine and an amino acid simultaneously. Toxicity was determined by the method previously described and expressed as a critical concentration (C/sub cr/, mg Cu/liter) and in relative toxicity units (T/sub c/). The compounds investigated were obtained from the interaction between a bidentant ligand of an azomethine or anamino acid and copper acetate in a water-alcohol medium at pH 6-8. Since they are not very soluble in water, true solutions were obtained by using dimethyl sulfoxide.

Synthesis and characterization of dihexyldithiocarbamate as a chelating agent in extraction of gold(III)

Energy Technology Data Exchange (ETDEWEB)

Fatimah, Soja Siti, E-mail: soja-sf@upi.edu [Departemen Pendidikan Kimia, Universitas Pendidikan Indonesia, Jl. Dr. Setiabudhi No. 229, Bandung 40154 (Indonesia); Department of Chemistry, Faculty of Mathematics and Natural Sciences, Padjadjaran University, Jl. Raya Bandung-Sumedang, Km. 21, Jatinangor (Indonesia); Bahti, Husein H.; Hastiawan, Iwan [Department of Chemistry, Faculty of Mathematics and Natural Sciences, Padjadjaran University, Jl. Raya Bandung-Sumedang, Km. 21, Jatinangor (Indonesia); Permanasari, Anna [Departemen Pendidikan Kimia, Universitas Pendidikan Indonesia, Jl. Dr. Setiabudhi No. 229, Bandung 40154 (Indonesia)

2016-02-08

The use of dialkyldithiocarbamates as chelating agents of transition metals have been developing for decades. Many chelating agents have been synthesized and used in the extraction of the metals. Studies on particular aspects of extraction of the metals, such as the effect of increasing hydrophobicity of chelating agents on the effectiveness of the extraction, have been done. However, despite the many studies on the synthesis and applications of this type of chelating agents, interests in the aspect of molecular structure of the synthesized ligands and of their complexes, have been limited. This study aimed at synthesizing and characterizing dihexylthiocarbamate, and using the ligand for the extraction of gold III). Characterization of the ligand and of its metal complex were done by using elemental analysis, DTG, and spectroscopic methods to include NMR, ({sup 1}H, and {sup 13}C), FTIR, and MS-ESI. Data on the synthesis, characterization, and the application of the ligand as a chelating agent are presented.

Synthesis and characterization of dihexyldithiocarbamate as a chelating agent in extraction of gold(III)

Science.gov (United States)

Fatimah, Soja Siti; Bahti, Husein H.; Hastiawan, Iwan; Permanasari, Anna

2016-02-01

The use of dialkyldithiocarbamates as chelating agents of transition metals have been developing for decades. Many chelating agents have been synthesized and used in the extraction of the metals. Studies on particular aspects of extraction of the metals, such as the effect of increasing hydrophobicity of chelating agents on the effectiveness of the extraction, have been done. However, despite the many studies on the synthesis and applications of this type of chelating agents, interests in the aspect of molecular structure of the synthesized ligands and of their complexes, have been limited. This study aimed at synthesizing and characterizing dihexylthiocarbamate, and using the ligand for the extraction of gold III). Characterization of the ligand and of its metal complex were done by using elemental analysis, DTG, and spectroscopic methods to include NMR, (1H, and 13C), FTIR, and MS-ESI. Data on the synthesis, characterization, and the application of the ligand as a chelating agent are presented.

Pretargeting of human mammary carcinoma xenografts with bispecific anti-MUC1/anti-Ga chelate antibodies and immunoscintigraphy with PET

International Nuclear Information System (INIS)

Schuhmacher, Jochen; Klivenyi, Gabor; Kaul, Sepp; Henze, Marcus; Matys, Ronald; Hauser, Harald; Clorius, John

2001-01-01

We recently demonstrated the feasibility of combining enhanced tumor-to-tissue contrast and PET imaging for immunoscintigraphic tumor localization in pancreas and colon carcinoma bearing nude mice. Contrast enhancement was obtained with a multistep targeting technique that consists of the sequential administration of an antitumor/antihapten bispecific antibody (BS-MAb), a blocker to saturate the antihapten binding sites of the BS-MAb that remains in circulation, and a low molecular weight Ga chelate, labeled with the positron emitter 68 Ga, which serves as the hapten. To evaluate the efficacy of this pretargeting technique for breast cancer localization, we synthesized a BS-MAb from the F(ab') 2 fragments of the anti-MUC1 MAb 12H12 which reacts with the vast majority of human breast carcinomas, and the F(ab') fragment of an anti-Ga chelate MAb using a bifunctional chemical linker. The BS-MAb was tested for its affinity and its biokinetics in nude mice bearing a human mammary carcinoma. Equilibrium binding of the BS-MAb for mammary carcinoma cells was low (1.2 x 10 7 M -1 ) while the binding capacity of cells was high (8.4 x 10 6 BS-MAbs per cell). Tumor uptake of the 67 Ga labeled chelate in pretargeted animals was to 5.8 ± 0.8% iD/g resulting in a tumor-to-blood ratio of 2.6 at 1h postinjection. This compares with a ratio of 0.65 and 0.85 obtained with 125 I-labeled native 12H12 at 24h and 48h postinjection. No difference in the tumor uptake of both the 68 Ga and 67 Ga labeled chelate was observed. PET imaging of mice, started 1h postinjection of the 68 Ga chelate, clearly visualized all tumors

Pretargeting of human mammary carcinoma xenografts with bispecific anti-MUC1/anti-Ga chelate antibodies and immunoscintigraphy with PET

Energy Technology Data Exchange (ETDEWEB)

Schuhmacher, Jochen; Klivenyi, Gabor; Kaul, Sepp; Henze, Marcus; Matys, Ronald; Hauser, Harald; Clorius, John

2001-10-01

We recently demonstrated the feasibility of combining enhanced tumor-to-tissue contrast and PET imaging for immunoscintigraphic tumor localization in pancreas and colon carcinoma bearing nude mice. Contrast enhancement was obtained with a multistep targeting technique that consists of the sequential administration of an antitumor/antihapten bispecific antibody (BS-MAb), a blocker to saturate the antihapten binding sites of the BS-MAb that remains in circulation, and a low molecular weight Ga chelate, labeled with the positron emitter {sup 68}Ga, which serves as the hapten. To evaluate the efficacy of this pretargeting technique for breast cancer localization, we synthesized a BS-MAb from the F(ab'){sub 2} fragments of the anti-MUC1 MAb 12H12 which reacts with the vast majority of human breast carcinomas, and the F(ab') fragment of an anti-Ga chelate MAb using a bifunctional chemical linker. The BS-MAb was tested for its affinity and its biokinetics in nude mice bearing a human mammary carcinoma. Equilibrium binding of the BS-MAb for mammary carcinoma cells was low (1.2 x 10{sup 7} M{sup -1}) while the binding capacity of cells was high (8.4 x 10{sup 6} BS-MAbs per cell). Tumor uptake of the {sup 67}Ga labeled chelate in pretargeted animals was to 5.8 {+-} 0.8% iD/g resulting in a tumor-to-blood ratio of 2.6 at 1h postinjection. This compares with a ratio of 0.65 and 0.85 obtained with {sup 125}I-labeled native 12H12 at 24h and 48h postinjection. No difference in the tumor uptake of both the {sup 68}Ga and {sup 67}Ga labeled chelate was observed. PET imaging of mice, started 1h postinjection of the {sup 68}Ga chelate, clearly visualized all tumors.

Coupling fast water exchange to slow molecular tumbling in Gd3+ chelates: why faster is not always better.

Science.gov (United States)

Avedano, Stefano; Botta, Mauro; Haigh, Julian S; Longo, Dario L; Woods, Mark

2013-08-05

The influence of dynamics on solution state structure is a widely overlooked consideration in chemistry. Variations in Gd(3+) chelate hydration with changing coordination geometry and dissociative water exchange kinetics substantially impact the effectiveness (or relaxivity) of monohydrated Gd(3+) chelates as T1-shortening contrast agents for MRI. Theory shows that relaxivity is highly dependent upon the Gd(3+)-water proton distance (rGdH), and yet this distance is almost never considered as a variable in assessing the relaxivity of a Gd(3+) chelate as a potential contrast agent. The consequence of this omission can be seen when considering the relaxivity of isomeric Gd(3+) chelates that exhibit different dissociative water exchange kinetics. The results described herein show that the relaxivity of a chelate with "optimal" dissociative water exchange kinetics is actually lower than that of an isomeric chelate with "suboptimal" dissociative water exchange. When the rate of molecular tumbling of these chelates is slowed, an approach that has long been understood to increase relaxivity, the observed difference in relaxivity is increased with the more rapidly exchanging ("optimal") chelate exhibiting lower relaxivity than the "suboptimally" exchanging isomer. The difference between the chelates arises from a non-field-dependent parameter: either the hydration number (q) or rGdH. For solution state Gd(3+) chelates, changes in the values of q and rGdH are indistinguishable. These parametric expressions simply describe the hydration state of the chelate--i.e., the number and position of closely associating water molecules. The hydration state (q/rGdH(6)) of a chelate is intrinsically linked to its dissociative water exchange rate kex, and the interrelation of these parameters must be considered when examining the relaxivity of Gd(3+) chelates. The data presented herein indicate that the changes in the hydration parameter (q/rGdH(6)) associated with changing dissociative

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

Science.gov (United States)

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.

High precision isotopic ratio analysis of volatile metal chelates

International Nuclear Information System (INIS)

Hachey, D.L.; Blais, J.C.; Klein, P.D.

1980-01-01

High precision isotope ratio measurements have been made for a series of volatile alkaline earth and transition metal chelates using conventional GC/MS instrumentation. Electron ionization was used for alkaline earth chelates, whereas isobutane chemical ionization was used for transition metal studies. Natural isotopic abundances were determined for a series of Mg, Ca, Cr, Fe, Ni, Cu, Cd, and Zn chelates. Absolute accuracy ranged between 0.01 and 1.19 at. %. Absolute precision ranged between +-0.01-0.27 at. % (RSD +- 0.07-10.26%) for elements that contained as many as eight natural isotopes. Calibration curves were prepared using natural abundance metals and their enriched 50 Cr, 60 Ni, and 65 Cu isotopes covering the range 0.1-1010.7 at. % excess. A separate multiple isotope calibration curve was similarly prepared using enriched 60 Ni (0.02-2.15 at. % excess) and 62 Ni (0.23-18.5 at. % excess). The samples were analyzed by GC/CI/MS. Human plasma, containing enriched 26 Mg and 44 Ca, was analyzed by EI/MS. 1 figure, 5 tables

Antitumor effect of combination of the inhibitors of two new oncotargets: proton pumps and reverse transcriptase.

Science.gov (United States)

Lugini, Luana; Sciamanna, Ilaria; Federici, Cristina; Iessi, Elisabetta; Spugnini, Enrico Pierluigi; Fais, Stefano

2017-01-17

Tumor therapy needs new approaches in order to improve efficacy and reduce toxicity of the current treatments. The acidic microenvironment and the expression of high levels of endogenous non-telomerase reverse transcriptase (RT) are common features of malignant tumor cells. The anti-acidic proton pump inhibitor Lansoprazole (LAN) and the non-nucleoside RT inhibitor Efavirenz (EFV) have shown independent antitumor efficacy. LAN has shown to counteract drug tumor resistance. We tested the hypothesis that combination of LAN and EFV may improve the overall antitumor effects. We thus pretreated human metastatic melanoma cells with LAN and then with EFV, both in 2D and 3D spheroid models. We evaluated the treatment effect by proliferation and cell death/apoptosis assays in classical and in pulse administration experiments. The action of EFV was negatively affected by the tumor microenvironmental acidity, and LAN pretreatment overcame the problem. LAN potentiated the cytotoxicity of EFV to melanoma cells and, when administered during the drug interruption period, prevented the replacement of tumor cell growth.This study supports the implementation of the current therapies with combination of Proton Pumps and Reverse Transcriptase inhibitors.

Red Blood Cell Transfusion Independence Following the Initiation of Iron Chelation Therapy in Myelodysplastic Syndrome

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Maha A. Badawi

2010-01-01

Full Text Available Iron chelation therapy is often used to treat iron overload in patients requiring transfusion of red blood cells (RBC. A 76-year-old man with MDS type refractory cytopenia with multilineage dysplasia, intermediate-1 IPSS risk, was referred when he became transfusion dependent. He declined infusional chelation but subsequently accepted oral therapy. Following the initiation of chelation, RBC transfusion requirement ceased and he remained transfusion independent over 40 months later. Over the same time course, ferritin levels decreased but did not normalize. There have been eighteen other MDS patients reported showing improvement in hemoglobin level with iron chelation; nine became transfusion independent, nine had decreased transfusion requirements, and some showed improved trilineage myelopoiesis. The clinical features of these patients are summarized and possible mechanisms for such an effect of iron chelation on cytopenias are discussed.

Reaction of gadolinium chelates with ozone and hydroxyl radicals.

Science.gov (United States)

Cyris, Maike; Knolle, Wolfgang; Richard, Jessica; Dopp, Elke; von Sonntag, Clemens; Schmidt, Torsten C

2013-09-03

Gadolinium chelates are used in increasing amounts as contrast agents in magnetic resonance imaging, and their fate in wastewater treatment has recently become the focus of research. Oxidative processes, in particular the application of ozone, are currently discussed or even implemented for advanced wastewater treatment. However, reactions of the gadolinium chelates with ozone are not yet characterized. In this study, therefore, rate constants with ozone were determined for the three commonly used chelates Gd-DTPA, Gd-DTPA-BMA, and Gd-BT-DO3A, which were found to be 4.8 ± 0.88, 46 ± 2.5, and 24 ± 1.5 M(-1) s(-1), respectively. These low rate constants indicate that a direct reaction with ozone in wastewater is negligible. However, application of ozone in wastewater leads to substantial yields of (•)OH. Different methods have been applied and compared for determination of k((•)OH+Gd chelate). From rate constants determined by pulse radiolysis experiments (k((•)OH+Gd-DTPA) = 2.6 ± 0.2 × 10(9) M(-1) s(-1), k((•)OH+Gd-DTPA-BMA) = 1.9 ± 0.7 × 10(9) M(-1) s(-1), k((•)OH+Gd-BT-DO3A) = 4.3 ± 0.2 × 10(9) M(-1) s(-1)), it is concluded that a reaction in wastewater via (•)OH radicals is feasible. Toxicity has been tested for educt and product mixtures of both reactions. Cytotoxicity (MTT test) and genotoxicity (micronuclei assay) were not detectable.

Fabrication of Surface Protein-Imprinted Nanoparticles Using a Metal Chelating Monomer via Aqueous Precipitation Polymerization.

Science.gov (United States)

Li, Wei; Sun, Yan; Yang, Chongchong; Yan, Xianming; Guo, Hao; Fu, Guoqi

2015-12-16

Molecular imprinting is a promising way for constructing artificial protein recognition materials, but it has been challenged by difficulties such as restricted biomacromolecule transfer in the cross-linked polymer networks, and reduced template-monomer interactions that are due to the required aqueous media. Herein, we propose a strategy for imprinting of histidine (His)-exposed proteins by combining previous approaches such as surface imprinting over nanostructures, utilization of metal coordination interactions, and adoption of aqueous precipitation polymerization capable of forming reversible physical crosslinks. With lysozyme as a model template bearing His residues, imprinted polymer nanoshells were grafted over vinyl-modified nanoparticles by aqueous precipitation copolymerization of a Cu(2+) chelating monomer with a temperature-responsive monomer carried out at 37 °C, above the volume phase-transition temperature (VPTT) of the final copolymer. The imprinted nanoshells showed significant temperature sensitivity and the template removal could be facilitated by swelling of the imprinted layers at 4 °C, below the VPTT. The resultant core-shell imprinted nanoparticles exhibited strikingly high rebinding selectivity against a variety of nontemplate proteins. An imprinting factor up to 22.7 was achieved, which is among the best values reported for protein imprinting, and a rather high specific binding capacity of 67.3 mg/g was obtained. Moreover, this approach was successfully extended to preliminary imprinting of hemoglobin, another protein with accessible His. Therefore, it may be a versatile method for fabrication of high-performance surface-imprinted nanoparticles toward His-exposed proteins.

Antimicrobial Properties of Copper Nanoparticles and Amino Acid Chelated Copper Nanoparticles Produced by Using a Soya Extract

Science.gov (United States)

DeAlba-Montero, I.; Morales-Sánchez, Elpidio; Araujo-Martínez, Rene

2017-01-01

This paper reports a comparison of the antibacterial properties of copper-amino acids chelates and copper nanoparticles against Escherichia coli, Staphylococcus aureus, and Enterococcus faecalis. These copper-amino acids chelates were synthesized by using a soybean aqueous extract and copper nanoparticles were produced using as a starting material the copper-amino acids chelates species. The antibacterial activity of the samples was evaluated by using the standard microdilution method (CLSI M100-S25 January 2015). In the antibacterial activity assays copper ions and copper-EDTA chelates were included as references, so that copper-amino acids chelates can be particularly suitable for acting as an antibacterial agent, so they are excellent candidates for specific applications. Additionally, to confirm the antimicrobial mechanism on bacterial cells, MTT assay (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) was carried out. A significant enhanced antimicrobial activity and a specific strain were found for copper chelates over E. faecalis. Its results would eventually lead to better utilization of copper-amino acids chelate for specific application where copper nanoparticles can be not used. PMID:28286459

REVIEW ARTICLE:Future of Lead Chelation – Distribution and Treatment

Directory of Open Access Journals (Sweden)

Venkatesh Thuppil

2012-01-01

Full Text Available Lead is the major environmental toxin resulting in the ill health and deleterious effect on almost all organs in the human body in a slow and effective manner. The best treatment for lead poisoning is chelation therapy which is next only to prevention. The authors describe the disruption of homeostasis of the human body by lead in various tissues like blood, bones, liver, kidneys and brain; and the ability of lead to enter the cell using calcium channels and calcium receptors like Ca++ dependant K+ ion channels, transient receptor potential channels, T-tubules, calmodulin receptors, inositol trisphosphate receptors and ryanodine receptors. We report a few novel chelating agents like ionophores, decadentate ligands, picolinate ligands, octadentate ligand, allicin, thiamine, that show good potential for being used in chelation therapy. Future of leadpoisoning is a challenge to all and it needs to be meticulously studies to have an economic and health approach.

Isotopic measurement of uranium using NP-type chelate resin beads

International Nuclear Information System (INIS)

Wu Lanbi; Chen Wenpo; Wang Shijun

1994-08-01

NP-type chelate resin beads is used as a carrier of samples in the isotopic measurements of uranium by mass spectrometry. The results show that its absorption efficiency for uranium can be greater than 50%. It is one order magnitude higher than that strong basic anion resin, however, the ionization efficiencies of both are almost the same. Therefore, the amount of uranium required for isotopic analysis can be reduced one order of magnitude. This method has been used for isotopic analysis of uranium in NP-type chelate resin beads contained 10 -9 ∼ 10 -7 g uranium. For standard sample UTB-500, the external precision of measurements are within +-0.2%, for natural uranium samples are within +- 0.5%. The application of NP-type chelate resin beads in the isotopic measurement of uranium is a new creative achievement. It has been used in the depletion test of uranium-atomic vapor laser isotope separation

Radiopharmaceutical chelates and method of external imaging

International Nuclear Information System (INIS)

Loberg, M.D.; Callery, P.S.; Cooper, M.

1977-01-01

A chelate of technetium-99m, cobalt-57, gallium-67, gallium-68, indium-111 or indium-113m and a substituted iminodiacetic acid or an 8-hydroxyquinoline useful as a radiopharmaceutical external imaging agent. The invention also includes preparative methods therefor

Preparation and Properties of the Chitosan/PVA Blend for Heavy Metals Chelation

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Zuhair Jabbar Abdul Ameer

2016-09-01

Full Text Available Current research based on the use of extracted chitosan mixed with Polyvinyl alcohol to manufacture blend that can been used in water purification from heavy metals such as copper, this due to chitosan properties and its ability to chelation these metals because of the presence of the functional groups in their structure. The blend has been treated with borax to increase the viscosity, and then high density polyethylene granulated coated with polymer solution to increase the surface area for chelation. The ultraviolet test showed the efficiency of blend to chelation of copper ions through lower the copper ions absorbance peak after each stage where the solution of copper ions pass on the polymer blend containing chitosan.

Simultaneous Determination of Chelating Agents by Ion-Suppression and Ion-Pair Chromatography in Wastewater

International Nuclear Information System (INIS)

Dodi, Alain; Bouscarel, Maelle

2008-01-01

This article describes two methods for analysing chelating agents found in nuclear waste. First, ion-suppression chromatography using an anion exchange stationary phase and mobile phase consisting of a nitric acid solution and pure water gradient. UV detection was performed at 330 nm after the reaction with a post-column reagent composed of iron nitrate in perchloric acid. Secondly, ion-pair chromatography with a mobile phase consisting of a mixture of nitric acid, tetra-butyl-ammonium hydrogeno-sulphate, tetra-butyl-ammonium hydroxide and iron chloride. A reversed-phase material was used as a stationary phase and detection was performed by direct measurement of the UV absorption at 260 nm. The quantification limits were lower for ion-pair chromatography than for ion-suppression chromatography. Both methods were easy to implement and allow a multi-element separation in less than 30 min with low detection limits. (authors)

Simultaneous Determination of Chelating Agents by Ion-Suppression and Ion-Pair Chromatography in Wastewater

Energy Technology Data Exchange (ETDEWEB)

Dodi, Alain; Bouscarel, Maelle [Commissariat a l' energie atomique - C.E.A, Centre d' Etude de Cadarache, Laboratoire d' Analyses Radiochimiques et Chimiques, St Paul lez Durance (France)

2008-07-01

This article describes two methods for analysing chelating agents found in nuclear waste. First, ion-suppression chromatography using an anion exchange stationary phase and mobile phase consisting of a nitric acid solution and pure water gradient. UV detection was performed at 330 nm after the reaction with a post-column reagent composed of iron nitrate in perchloric acid. Secondly, ion-pair chromatography with a mobile phase consisting of a mixture of nitric acid, tetra-butyl-ammonium hydrogeno-sulphate, tetra-butyl-ammonium hydroxide and iron chloride. A reversed-phase material was used as a stationary phase and detection was performed by direct measurement of the UV absorption at 260 nm. The quantification limits were lower for ion-pair chromatography than for ion-suppression chromatography. Both methods were easy to implement and allow a multi-element separation in less than 30 min with low detection limits. (authors)

MRI marrow observations in thalassemia: the effects of the primary disease, transfusional therapy, and chelation

International Nuclear Information System (INIS)

Levin, T.L.; Sheth, S.S.; Ruzal-Shapiro, C.; Abramson, S.; Piomelli, S.; Berdon, W.E.

1995-01-01

The magnetic resonance bone marrow patterns in thalassemia were evaluated to determine changes produced by transfusion and chelation therapy. Thirteen patients had T1- and T2-weighted images of the spine, pelvis and femurs. Three received no therapy (age range 2.5-3 years). Three were ''hypertransfused'' (transfused to maintain a hemoglobin greater than 10 g/dl) and not chelated because of age (age range 6 months-8 years). Seven were ''hypertransfused'' and chelated (age range 12-35 years). Signal characteristics of marrow were compared with those of surrounding muscle and fat. Fatty marrow (isointense with subcutaneous fat) was compared with red marrow (hypointense to fat and slightly hyperintense to muscle). Marrow hypointense to muscle was identified as iron deposition within red marrow. The untreated group demonstrated signal consistent with red marrow throughout the central and peripheral skeleton. Hypertransfused but not chelated patients demonstrated marked iron deposition in the central and peripheral skeleton. Hypertransfused and chelated patients demonstrated iron deposition in the central skeleton and a mixed appearance of marrow in the peripheral skeleton. The MR appearance of marrow in thalassemia is a reflection of the patient's transfusion and chelation therapy. Iron deposition occurs despite chelation therapy in sites of active red marrow. As red marrow retreats centrally with age, so does the pattern of iron deposition. The long-term biological effects of this iron deposition are unknown. (orig.). With 8 figs., 1 tab

Potentiometric study of Nd3+ chelates of substituted salicylhydroxamic acids

International Nuclear Information System (INIS)

Deshpande, R.G.; Jahagirdar, D.V.

1976-01-01

The interaction of Nd 3+ ion with salicylhydroxamic acid and 5-methyl, 5-chloro, 5-bromo, 5-nitro, 4-chloro, 4-bromo and 3-chloro salicylhydroxamic acids is investigated potentiometrically by Calvin-Bjerrum titration technique at 30 0 +- 0.1 0 and ionic strength μ=0.1 M(NaClO 4 ) in 50% v/v dioxane-water mixtures. Nd 3+ forms only 1:1 chelates with these ligands. The validity of the log K= apk + b relationship is examined for these chelates. (author)

Self-diffusion coefficient of iron as affected by chelating agents using tracer technique

International Nuclear Information System (INIS)

Massoud, M.A.; Abd-El-Sabour, M.F.; Omar, M.A.

1983-01-01

The effect of Fe 2 (So 4 ) 3 , Fe-DTPA, and Fe-EDDHA on the self-diffusion coefficient of Fe in some soils of Egypt was studied. The effect of chelating compounds on the ratio between solid phase fraction of the labile Fe and its concentration in the soil solution (capacity factor) was also studied. The data reveals the following items of more interesting: 1) The use of chelating agents, i.e., DTPA and EDDHA increased the amount of Fe in soil solution, hence the capacity factor was decreased using these compounds. It seems that as the addition of Fe was in the chelated form in soil solution, the slight loss of 59Fe from solution when 59Fe - chelate was used could be attributed to the isotopic exchange with soil Fe. 2) It was found that the addition of either Fe-DTPA or Fe-EDDHA significantly increased the self-diffusion of Fe in soil as compared with Fe 2 (So 4 ) 3 . It was also noticed that the self-diffusion for Fe in the alluvial soil was greater than in the calcareous one due to the instance competition between Ca and Fe for the chelating ligands in the calcareous soil. It was also seen that soil texture affects Fe self-diffusion

Preparation, characterization, magnetic and thermal studies of some chelate polymers of first series transition metal ions

International Nuclear Information System (INIS)

Ukey, Vaishali V.; Juneja, H.D.; Borkar, S.D.; Ghubde, R.S.; Naz, S.

2006-01-01

Azelaoyl-bis-hydroxamic acid used as bis ligand for the preparation of chelate polymers of Mn(II), Co(II), Ni(II) and Zn(II). These chelate polymers have been synthesized by refluxing the metal acetate and bis ligand as 1:1 stoichiometry. In the present work, structural determination of these newly synthesized chelate polymers has been studied on the basis of elemental analyses, infrared and reflectance spectral, magnetic and thermal studies. The decomposition temperature and the order of reaction have been determined by TGA analysis. On the basis of these studies, the Zn(II) chelate polymer has tetrahedral geometry, whereas Mn(II), Co(II) and Ni(II) chelate polymers have octahedral geometry and have the thermal stability in the order Ni(II) > Mn(II) > Zn(II) > Co(II)

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

Science.gov (United States)

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

Effects of solvent and chelating agent on synthesis of solid oxide fuel cell perovskite, La0.8Sr0.2CrO3-δ

International Nuclear Information System (INIS)

Lee, Byoung I.; Gupta, Ravindra K.; Whang, Chin M.

2008-01-01

Effects of solvent and chelating agent on synthesis of La 0.8 Sr 0.2 CrO 3-δ perovskite are reported. Samples are synthesized using a solvent (ethylene glycol or 2-methoxyethanol) and a chelating agent (acetylacetone, citric acid or ethylene diamine tetraacetic acid) by polymeric-gel method, and characterized by X-ray diffractometry and Fourier-transform infrared spectroscopy. Citric acid to metal cations molar ratio (Rc) is varied for ethylene glycol-citric acid system. Samples are mainly orthorhombic perovskite. SrCrO 4 is appeared as a secondary phase and found to be the lowest for ethylene glycol-citric acid combination with Rc equal to 7. Crystallographic parameters of perovskite phase are determined and compared with those of LaCrO 3 . A mechanism employing a partial-charge model, chelating effect and solvent-cage effect is proposed to explain the results. Effect of sintering temperature on phase, relative density and morphology of samples prepared using ethylene glycol and citric acid (Rc = 7) is also reported

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

International Nuclear Information System (INIS)

Muchlisyam; Harahap, U; Silalahi, J.; Zul Alfian

2013-01-01

Corn cobs is an agricultural byproduct containing polysaccharide composed of cellulose, hemicelluloses and lignin. Hemicelluloses has a hydroxyl and carbonyl functional groups which can be used as chelating agent for metal ions. The purpose of this study was to isolate and evaluate corncobs hemicelluloses as a chelating agent toward lead ion. Graphite furnace spectrophotometry at 283.3 nm was used to determine the residual lead ion in solution. The research's result showed that the highest yield of hemicelluloses (12.04 %) was obtained from delignication with 0,03 M NaOH in 60 % ethanol and 3 % H 2 O 2 , hemicelluloses isolation with 500 ml of 0.2 M NaOH, and precipitation with 1:4 ratio of 10 % acetic acid in 95 % ethanol. The 300 mg corn cobs hemicelluloses has chelating effect for 40 mg lead solution at (39.52±0.1350) mg or 98.80 %, that the corn cobs hemicelluloses can be used as a chelating agent for lead. (author)

Study of chelating agent as a surface modifier for retarding corrosion attack on ferrous metal

International Nuclear Information System (INIS)

Nur Ubaidah Saidin; Muhamad Daud; Siti Radiah Mohd Kamarudin; Zaifol Samsu; Azali Muhamad; Rusni Rejab; Mohd Saari Ripin; Mohd Shariff Sattar

2010-01-01

A different concentration of chelating agents in electrolyte of 3.5 % NaCl was applied to bare ferrous metal and tested for their effectiveness as a corrosion retardant. The performance of the samples was measured using corrosion measurement system. The results indicated that the contribution of chelating agent was expediting the reduction of the passive film. The anodic behavior was clearly found to be influenced by the concentration of the chelating agent. It was also found that some of the corrosion was apparently converted to protective layer over a period of time. Excessive moisture caused breakdown of film by removing the unreacted chelating agent and causing regrowth of the existing rust. (author)

Mechanism and efficiency of cell death of type II photosensitizers: effect of zinc chelation.

Science.gov (United States)

Pavani, Christiane; Iamamoto, Yassuko; Baptista, Maurício S

2012-01-01

A series of meso-substituted tetra-cationic porphyrins, which have methyl and octyl substituents, was studied in order to understand the effect of zinc chelation and photosensitizer subcellular localization in the mechanism of cell death. Zinc chelation does not change the photophysical properties of the photosensitizers (all molecules studied are type II photosensitizers) but affects considerably the interaction of the porphyrins with membranes, reducing mitochondrial accumulation. The total amount of intracellular reactive species induced by treating cells with photosensitizer and light is similar for zinc-chelated and free-base porphyrins that have the same alkyl substituent. Zinc-chelated porphyrins, which are poorly accumulated in mitochondria, show higher efficiency of cell death with features of apoptosis (higher MTT response compared with trypan blue staining, specific acridine orange/ethidium bromide staining, loss of mitochondrial transmembrane potential, stronger cytochrome c release and larger sub-G1 cell population), whereas nonchelated porphyrins, which are considerably more concentrated in mitochondria, triggered mainly necrotic cell death. We hypothesized that zinc-chelation protects the photoinduced properties of the porphyrins in the mitochondrial environment. © 2012 Wiley Periodicals, Inc. Photochemistry and Photobiology © 2012 The American Society of Photobiology.

Effect of the chelation of metal cation on the antioxidant activity of chondroitin sulfates.

Science.gov (United States)

Ajisaka, Katsumi; Oyanagi, Yutaka; Miyazaki, Tatsuo; Suzuki, Yasuhiro

2016-06-01

The antioxidant potencies of chondroitin sulfates (CSs) from shark cartilage, salmon cartilage, bovine trachea, and porcine intestinal mucosa were compared by three representative methods for the measurement of the antioxidant activity; DPPH radical scavenging activity, superoxide radical scavenging activity, and hydroxyl radical scavenging activity. CSs from salmon cartilage and bovine trachea showed higher potency in comparison with CSs from shark cartilage and porcine intestinal mucosa. Next, CS from salmon cartilage chelating with Ca(2+), Mg(2+), Mn(2+), or Zn(2+) were prepared, and their antioxidant potencies were compared. CS chelating with Ca(2+) or Mg(2+) ions showed rather decreased DPPH radical scavenging activity in comparison with CS of H(+) form. In contrast, CS chelating with Ca(2+) or Mg(2+) ion showed remarkably enhanced superoxide radical scavenging activity than CS of H(+) or Na(+) form. Moreover, CS chelating with divalent metal ions, Ca(2+), Mg(2+), Mn(2+), or Zn(2+), showed noticeably higher hydroxyl radical scavenging activity than CS of H(+) or Na(+) form. The present results revealed that the scavenging activities of, at least, superoxide radical and hydroxyl radical were enhanced by the chelation with divalent metal ions.

Enhancement of 67Ga tumor-to-blood ratios by chelating agent

International Nuclear Information System (INIS)

Saji, Hideo; Yokoyama, Akira; Hata, Naotaka; Misaki, Atsushi; Tanaka, Hisashi.

1980-01-01

Chelating agent, such as, CaEDTA, CaDTPA, D-penicillamine, DMSA, desferoxamine, NTA, cysteine ethyl ester, BAL, α-MPG, phthalein complexone, were tested as a possible contrast enhancing agent for tumor imaging with 67 Ga-citrate. The intravenous administration of a chelating agent to Ehrlich's tumor bearing mice, one hour after the injection of 67 Ga-citrate, accelerated the blood clearance with only a very slight change of activity in the target, increasing the tumor-to-blood ratio, and consequently achieving a better visualization. Among the tested chelating agents, D-penicillamine showed the highest target-to-nontarget ratio at a shorter time: a good tumor-to-blood ratio, performed after 24 hr with non-treated animals, was achieved in only 1-3 hr with post-treated animals. Thus, D-penicillamine hold a considerable promise as a contrast enhancing agent for future clinical use. (author)

Self-diffusion coefficient of iron as affected by chelating agents using tracer technique

Energy Technology Data Exchange (ETDEWEB)

Massoud, M.A.; Abd-El-Sabour, M.F. (Agriculture Dept. for Soil and Water Research, Nuclear Research Centre, A.E.A., Cairo (Egypt)); Omar, M.A. (Ain Shams Univ., Cairo (Egypt). Faculty of Agriculture)

1983-01-01

The effect of Fe/sub 2/(So/sub 4/)/sub 3/, Fe-DTPA, and Fe-EDDHA on the self-diffusion coefficient of Fe in some soils of Egypt was studied. The effect of chelating compounds on the ratio between solid phase fraction of the labile Fe and its concentration in the soil solution (capacity factor) was also studied. The data reveals the following items of more interesting: 1) The use of chelating agents, i.e., DTPA and EDDHA increased the amount of Fe in soil solution, hence the capacity factor was decreased using these compounds. It seems that as the addition of Fe was in the chelated form in soil solution, the slight loss of 59Fe from solution when 59Fe - chelate was used could be attributed to the isotopic exchange with soil Fe. 2) It was found that the addition of either Fe-DTPA or Fe-EDDHA significantly increased the self-diffusion of Fe in soil as compared with Fe/sub 2/(So/sub 4/)/sub 3/. It was also noticed that the self-diffusion for Fe in the alluvial soil was greater than in the calcareous one due to the instance competition between Ca and Fe for the chelating ligands in the calcareous soil. It was also seen that soil texture affects Fe self-diffusion.

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

Science.gov (United States)

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.

Profound morphological changes in the erythrocytes and fibrin networks of patients with hemochromatosis or with hyperferritinemia, and their normalization by iron chelators and other agents.

Directory of Open Access Journals (Sweden)

Etheresia Pretorius

Full Text Available It is well-known that individuals with increased iron levels are more prone to thrombotic diseases, mainly due to the presence of unliganded iron, and thereby the increased production of hydroxyl radicals. It is also known that erythrocytes (RBCs may play an important role during thrombotic events. Therefore the purpose of the current study was to assess whether RBCs had an altered morphology in individuals with hereditary hemochromatosis (HH, as well as some who displayed hyperferritinemia (HF. Using scanning electron microscopy, we also assessed means by which the RBC and fibrin morphology might be normalized. An important objective was to test the hypothesis that the altered RBC morphology was due to the presence of excess unliganded iron by removing it through chelation. Very striking differences were observed, in that the erythrocytes from HH and HF individuals were distorted and had a much greater axial ratio compared to that accompanying the discoid appearance seen in the normal samples. The response to thrombin, and the appearance of a platelet-rich plasma smear, were also markedly different. These differences could largely be reversed by the iron chelator desferal and to some degree by the iron chelator clioquinol, or by the free radical trapping agents salicylate or selenite (that may themselves also be iron chelators. These findings are consistent with the view that the aberrant morphology of the HH and HF erythrocytes is caused, at least in part, by unliganded ('free' iron, whether derived directly via raised ferritin levels or otherwise, and that lowering it or affecting the consequences of its action may be of therapeutic benefit. The findings also bear on the question of the extent to which accepting blood donations from HH individuals may be desirable or otherwise.

Spectroscopy, modeling and computation of metal chelate solubility in supercritical CO2. 1998 annual progress report

International Nuclear Information System (INIS)

Brennecke, J.F.; Chateauneuf, J.E.; Stadtherr, M.A.

1998-01-01

'This report summarizes work after 1 year and 8 months (9/15/96-5/14/98) of a 3 year project. Thus far, progress has been made in: (1) the measurement of the solubility of metal chelates in SC CO 2 with and without added cosolvents, (2) the spectroscopic determination of preferential solvation of metal chelates by cosolvents in SC CO 2 solutions, and (3) the development of a totally reliable computational technique for phase equilibrium computations. An important factor in the removal of metals from solid matrices with CO 2 /chelate mixtures is the equilibrium solubility of the metal chelate complex in the CO 2 .'

Combined Ideal and Kinetic Effects on Reversed Shear Alfven Eigenmodes

International Nuclear Information System (INIS)

Gorelenkov, N.N.; Kramer, G.J.; Nazikian, R.

2011-01-01

A theory of Reversed Shear Alfven Eigenmodes (RSAEs) is developed for reversed magnetic field shear plasmas when the safety factor minimum, qmin, is at or above a rational value. The modes we study are known sometimes as either the bottom of the frequency sweep or the down sweeping RSAEs. We show that the ideal MHD theory is not compatible with the eigenmode solution in the reversed shear plasma with qmin above integer values. Corrected by special analytic FLR condition MHD dispersion of these modes nevertheless can be developed. Large radial scale part of the analytic RSAE solution can be obtained from ideal MHD and expressed in terms of the Legendre functions. The kinetic equation with FLR effects for the eigenmode is solved numerically and agrees with the analytic solutions. Properties of RSAEs and their potential implications for plasma diagnostics are discussed.

Chelators for investigating zinc metalloneurochemistry

OpenAIRE

Radford, Robert John; Lippard, Stephen J.

2013-01-01

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

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

Science.gov (United States)

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.

Science.gov (United States)

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

Multiplex reverse transcription-polymerase chain reaction combined with on-chip electrophoresis as a rapid screening tool for candidate gene sets

DEFF Research Database (Denmark)

Wittig, Rainer; Salowsky, Rüdiger; Blaich, Stephanie

2005-01-01

Combining multiplex reverse transcription-polymerase chain reaction (mRT-PCR) with microfluidic amplicon analysis, we developed an assay for the rapid and reliable semiquantitative expression screening of 11 candidate genes for drug resistance in human malignant melanoma. The functionality of thi...

Brain antioxidant effect of mirtazapine and reversal of sedation by its combination with alpha-lipoic acid in a model of depression induced by corticosterone.

Science.gov (United States)

Oliveira, Tatiana de Queiroz; de Sousa, Caren Nádia Soares; Vasconcelos, Germana Silva; de Sousa, Luciene Costa; de Oliveira, Anneheydi Araújo; Patrocínio, Cláudio Felipe Vasconcelos; Medeiros, Ingridy da Silva; Honório Júnior, José Eduardo Ribeiro; Maes, Michael; Macedo, Danielle; Vasconcelos, Silvânia Maria Mendes

2017-09-01

Depression is accompanied by activated neuro-oxidative and neuro-nitrosative pathways, while targeting these pathways has clinical efficacy in depression. This study aimed to investigate the effects of mirtazapine (MIRT) alone and combined with alpha-lipoic acid (ALA) against corticosterone (CORT) induced behavioral and oxidative alterations. Male mice received vehicle or CORT 20mg/kg during 14 days. From the 15th to 21st days they were divided in groups administered: vehicle, MIRT 3mg/kg or the combinations MIRT+ALA100 or MIRT+ALA200. On the 21st day of treatment, the animals were subjected to behavioral tests. Twenty-four hours after the last drug administration hippocampus (HC) and striatum (ST) were dissected for the determination reduced glutathione (GSH), lipid peroxidation (LP) and nitrite levels. CORT induced anxiety- and depressive-like behaviors as observed by increased immobility time in the tail suspension test and decreased sucrose consumption. MIRT or MIRT+ALA are effective in reversing anxiety- and depressive-like behaviors induced by CORT. CORT and MIRT alone prolonged sleeping time and this effect was reversed by MIRT+ALA. CORT significantly increased LP, which was reversed by MIRT or MIRT+ALA. Nitrite levels were increased in CORT-treated animals and reversed by MIRT+ALA200 (HC), MIRT or MIRT+ALA (ST). A relative small sample size and lack of a washout period between drug administration and behavioral testing. MIRT or MIRT+ALA reverse CORT-induced anxiety- and depressive-like behaviors probably via their central antioxidant effects. Augmentation of MIRT with ALA may reverse sedation, an important side effect of MIRT. Randomized controlled studies are needed to examine the clinical efficacy of this combination in human depression. Copyright © 2017 Elsevier B.V. All rights reserved.

Chelation studies involving decontamination of light lanthanides by polyaminopolycarboxylic

International Nuclear Information System (INIS)

Hassan, N.E.H.

1985-01-01

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

Reversible arithmetic logic unit for quantum arithmetic

DEFF Research Database (Denmark)

Thomsen, Michael Kirkedal; Glück, Robert; Axelsen, Holger Bock

2010-01-01

This communication presents the complete design of a reversible arithmetic logic unit (ALU) that can be part of a programmable reversible computing device such as a quantum computer. The presented ALU is garbage free and uses reversible updates to combine the standard reversible arithmetic...... and logical operations in one unit. Combined with a suitable control unit, the ALU permits the construction of an r-Turing complete computing device. The garbage-free ALU developed in this communication requires only 6n elementary reversible gates for five basic arithmetic-logical operations on two n......-bit operands and does not use ancillae. This remarkable low resource consumption was achieved by generalizing the V-shape design first introduced for quantum ripple-carry adders and nesting multiple V-shapes in a novel integrated design. This communication shows that the realization of an efficient reversible...

Iron Chelators and Antioxidants Regenerate Neuritic Tree and Nigrostriatal Fibers of MPP+/MPTP-Lesioned Dopaminergic Neurons.

Directory of Open Access Journals (Sweden)

Pabla Aguirre

Full Text Available Neuronal death in Parkinson's disease (PD is often preceded by axodendritic tree retraction and loss of neuronal functionality. The presence of non-functional but live neurons opens therapeutic possibilities to recover functionality before clinical symptoms develop. Considering that iron accumulation and oxidative damage are conditions commonly found in PD, we tested the possible neuritogenic effects of iron chelators and antioxidant agents. We used three commercial chelators: DFO, deferiprone and 2.2'-dypyridyl, and three 8-hydroxyquinoline-based iron chelators: M30, 7MH and 7DH, and we evaluated their effects in vitro using a mesencephalic cell culture treated with the Parkinsonian toxin MPP+ and in vivo using the MPTP mouse model. All chelators tested promoted the emergence of new tyrosine hydroxylase (TH-positive processes, increased axodendritic tree length and protected cells against lipoperoxidation. Chelator treatment resulted in the generation of processes containing the presynaptic marker synaptophysin. The antioxidants N-acetylcysteine and dymetylthiourea also enhanced axodendritic tree recovery in vitro, an indication that reducing oxidative tone fosters neuritogenesis in MPP+-damaged neurons. Oral administration to mice of the M30 chelator for 14 days after MPTP treatment resulted in increased TH- and GIRK2-positive nigra cells and nigrostriatal fibers. Our results support a role for oral iron chelators as good candidates for the early treatment of PD, at stages of the disease where there is axodendritic tree retraction without neuronal death.

Chelation and stabilization of berkelium in oxidation state +IV

Science.gov (United States)

Deblonde, Gauthier J.-P.; Sturzbecher-Hoehne, Manuel; Rupert, Peter B.; An, Dahlia D.; Illy, Marie-Claire; Ralston, Corie Y.; Brabec, Jiri; de Jong, Wibe A.; Strong, Roland K.; Abergel, Rebecca J.

2017-09-01

Berkelium (Bk) has been predicted to be the only transplutonium element able to exhibit both +III and +IV oxidation states in solution, but evidence of a stable oxidized Bk chelate has so far remained elusive. Here we describe the stabilization of the heaviest 4+ ion of the periodic table, under mild aqueous conditions, using a siderophore derivative. The resulting Bk(IV) complex exhibits luminescence via sensitization through an intramolecular antenna effect. This neutral Bk(IV) coordination compound is not sequestered by the protein siderocalin—a mammalian metal transporter—in contrast to the negatively charged species obtained with neighbouring trivalent actinides americium, curium and californium (Cf). The corresponding Cf(III)-ligand-protein ternary adduct was characterized by X-ray diffraction analysis. Combined with theoretical predictions, these data add significant insight to the field of transplutonium chemistry, and may lead to innovative Bk separation and purification processes.

Nanopore Device for Reversible Ion and Molecule Sensing or Migration

Science.gov (United States)

Pourmand, Nader (Inventor); Vilozny, Boaz (Inventor); Actis, Paolo (Inventor); Seger, R. Adam (Inventor); Singaram, Bakthan (Inventor)

2015-01-01

Disclosed are methods and devices for detection of ion migration and binding, utilizing a nanopipette adapted for use in an electrochemical sensing circuit. The nanopipette may be functionalized on its interior bore with metal chelators for binding and sensing metal ions or other specific binding molecules such as boronic acid for binding and sensing glucose. Such a functionalized nanopipette is comprised in an electrical sensor that detects when the nanopipette selectively and reversibly binds ions or small molecules. Also disclosed is a nanoreactor, comprising a nanopipette, for controlling precipitation in aqueous solutions by voltage-directed ion migration, wherein ions may be directed out of the interior bore by a repulsing charge in the bore.

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

Science.gov (United States)

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.

Removal of heavy elements from Contaminated Matrices using amidoxime chelating starch

International Nuclear Information System (INIS)

Shama, S.A.; Wally, S.A.; Aly, H.F.

2012-01-01

The synthesis of a amidoxime chelating starch was carried out by grafting of acrylonitrile onto starch using the mutual irradiation techniques at dose rate 2.5 kGy. Conversion of nitrile groups of the grafted copolymer into the amidoxime was carried out by treatment with hydroxylamine under alkaline solution. The amidoxime chelating starch was characterized by FT-IR spectra, TG, Particle size, Surface area, SEM, and Elemental analyses. The chelating behavior of the prepared resin was carried out by using uranium. The binding capacity of uranium ion by the amidoxime resin was carried out by the batch technique. The sorption capacity was high for uranium, 86.9 mg/g at ph 6.5. The kinetic exchange rate was fast. It was observed that the uranium uptake ratio reaches 50% at 10 min (t 1/2 ). The treatment process using amidoxime sorbent is efficient to remove uranium from the waste solution of the FMPP plant.

Design of a novel quantum reversible ternary up-counter

Science.gov (United States)

Houshmand, Pouran; Haghparast, Majid

2015-08-01

Reversible logic has been recently considered as an interesting and important issue in designing combinational and sequential circuits. The combination of reversible logic and multi-valued logic can improve power dissipation, time and space utilization rate of designed circuits. Only few works have been reported about sequential reversible circuits and almost there are no paper exhibited about quantum ternary reversible counter. In this paper, first we designed 2-qutrit and 3-qutrit quantum reversible ternary up-counters using quantum ternary reversible T-flip-flop and quantum reversible ternary gates. Then we proposed generalized quantum reversible ternary n-qutrit up-counter. We also introduced a new approach for designing any type of n-qutrit ternary and reversible counter. According to the results, we can conclude that applying second approach quantum reversible ternary up-counter is better than the others.

Effects of lead and chelators on growth, photosynthetic activity and Pb uptake in Sesbania drummondii grown in soil

International Nuclear Information System (INIS)

Ruley, Adam T.; Sharma, Nilesh C.; Sahi, Shivendra V.; Singh, Shree R.; Sajwan, Kenneth S.

2006-01-01

Effects of lead (Pb) and chelators, such as EDTA, HEDTA, DTPA, NTA and citric acid, were studied to evaluate the growth potential of Sesbania drummondii in soils contaminated with high concentrations of Pb. S. drummondii seedlings were grown in soil containing 7.5 g Pb(NO 3 ) 2 and 0-10 mmol chelators/kg soil for a period of 2 and 4 weeks and assessed for growth profile (length of root and shoot), chlorophyll a fluorescence kinetics (F v /F m and F v /F o ) and Pb accumulations in root and shoot. Growth of plants in the presence of Pb + chelators was significantly higher (P v /F m and F v /F o values of treated seedlings remained unaffected, indicating normal photosynthetic efficiency and strength of plants in the presence of chelators. On application of chelators, while root uptake of Pb increased four-five folds, shoot accumulations increased up to 40-folds as compared to controls (Pb only) depending on the type of chelator used. Shoot accumulations of Pb varied from 0.1 to 0.42% (dry weight) depending on the concentration of chelators used. - Sesbania drummondii tolerates and accumulates high concentrations of Pb

Supercritical fluid reverse micelle separation

Science.gov (United States)

Fulton, J.L.; Smith, R.D.

1993-11-30

A method of separating solute material from a polar fluid in a first polar fluid phase is provided. The method comprises combining a polar fluid, a second fluid that is a gas at standard temperature and pressure and has a critical density, and a surfactant. The solute material is dissolved in the polar fluid to define the first polar fluid phase. The combined polar and second fluids, surfactant, and solute material dissolved in the polar fluid is maintained under near critical or supercritical temperature and pressure conditions such that the density of the second fluid exceeds the critical density thereof. In this way, a reverse micelle system defining a reverse micelle solvent is formed which comprises a continuous phase in the second fluid and a plurality of reverse micelles dispersed in the continuous phase. The solute material is dissolved in the polar fluid and is in chemical equilibrium with the reverse micelles. The first polar fluid phase and the continuous phase are immiscible. The reverse micelles each comprise a dynamic aggregate of surfactant molecules surrounding a core of the polar fluid. The reverse micelle solvent has a polar fluid-to-surfactant molar ratio W, which can vary over a range having a maximum ratio W[sub o] that determines the maximum size of the reverse micelles. The maximum ratio W[sub o] of the reverse micelle solvent is then varied, and the solute material from the first polar fluid phase is transported into the reverse micelles in the continuous phase at an extraction efficiency determined by the critical or supercritical conditions. 27 figures.

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

Science.gov (United States)

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.

Combined ideal and kinetic effects on reversed shear Alfven eigenmodes

International Nuclear Information System (INIS)

Gorelenkov, N. N.; Kramer, G. J.; Nazikian, R.

2011-01-01

A reversed shear Alfven eigenmodes (RSAEs) theory has been developed for reversed magnetic field shear plasmas when the safety factor minimum, q min , is at or above a rational value. The modes we study are known sometimes as either the bottom of the frequency sweep or the down sweeping RSAEs. We show that, strictly speaking, the ideal MHD theory is not compatible with the eigenmode solution in the reversed shear plasma with q min above integer values. Corrected by a special analytic finite Larmor radius (FLR) condition, MHD dispersion of these modes nevertheless can be developed. Numerically, MHD structure can serve as a good approximation for the RSAEs.The large radial scale part of the analytic RSAE solution can be obtained from ideal MHD and expressed in terms of the Legendre functions. The kinetic equation with FLR effects for the eigenmode is solved numerically and agrees with the analytic solutions. Properties of RSAEs and their potential implications for plasma diagnostics are discussed.

Chelated mineral supplements for Nelore: quality and early embryonic development

Directory of Open Access Journals (Sweden)

Camila Pasa

2014-01-01

Full Text Available ABSTRACT. Pasa C., Hatamoto-Zervoudakis L.K., Zervoudakis J.T. & Soares L. [Chelated mineral supplements for Nelore: quality and early embryonic development.] Suplementos minerais quelatados para vacas Nelore: qualidade e desenvolvimento embrionário inicial. Revista Brasileira de Medicina Veterinária, 36(1:29-34, 2014. Programa de Pós-Graduação em Ciência Animal, Faculdade de Agronomia e Medicina Veterinária, Universidade Federal do Mato Grosso, Av. Fernando Corrêa da Costa, 2367, Bairro Boa Esperança, Cuiabá, MT 78060-900, Brasil. E-mail: pasa_camila@hotmail.com The objective of this study was to evaluate the quality and early development of embryos produced with oocytes of cows supplemented with copper, zinc and selenium in a non-chelated and chelated. The experiment was conducted in Cuiabá-MT during the months April to July 2009. We used 24 adult Nellore multiparous, aged, average weights of the initial 36 months, 395 kg and mean body condition score 4.8, respectively randomly divided into 2 groups: control group (CG, supplemented with conventional mineral and Supplemented Group (GS, animals supplemented with zinc, copper and selenium chelated. Each group was kept in a paddock of Brachiaria brizantha cv Marandu received 1 kg of animal per day. chelated mineral supplementation (GS and conventional mineral (GC delivered via the protein supplement was given during a period of 99 days with daily average 1kg/cabeça. During the experimental period were two follicular aspirations, one to 59 days and another at 99 days of supplementation. Every two weeks the animals were weighed and ECC evaluated. oocytes viable (grades I, II and III were used for in vitro production of embryos. The experiment was completely randomized and data were analyzed by ANOVA and a significance level of 10%. There was no effect (p> 0.10 of supplementation with chelated minerals on the percentage of cleaved oocytes, total embryos produced, percentage of produced

Reverse amblyopia with atropine treatment.

Science.gov (United States)

Hainline, Bryan C; Sprunger, Derek C; Plager, David A; Neely, Daniel E; Guess, Matthew G

2009-01-01

Occlusion, pharmacologic pernalization and combined therapy have been documented in controlled studies to effectively treat amblyopia with few complications. However, there remain concerns about the effectiveness and complications when, as in this case, there are not standardized treatment protocols. A retrospective chart review of 133 consecutive patients in one community based ophthalmology practice treated for amblyopia was performed. Treatments evaluated were occlusion only, atropine penalization, and combination of occlusion and atropine. Reverse amblyopia was defined as having occured when the visual acuity of the sound eye was 3 LogMar units worse than visual acuity of the amblyopia eye after treatment. Improvement in vision after 6 months and 1 year of amblyopia therapy was similar among all three groups: 0.26 LogMar lines and 0.30 in the atropine group, 0.32 and 0.34 in the occlusion group, and 0.24 and 0.32 in the combined group. Eight (6%) patients demonstrated reverse amblyopia. The mean age of those who developed reverse amblyopia was 3.5 years, 1.5 years younger than the mean age of the study population, 7/8 had strabismic amblyopia, 6/8 were on daily atropine and had a mean refractive error of +4.77 diopters in the amblyopic eye and +5.06 diopters in the sound eye. Reverse amblyopia did not occur with occlusion only therapy. In this community based ophthalmology practice, atropine, patching, and combination therapy appear to be equally effective modalities to treat ambyopia. Highly hyperopic patients under 4 years of age with dense, strabismic amblyopia and on daily atropine appeared to be most at risk for development of reverse amblyopia.

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

Science.gov (United States)

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.

AAZTA: an ideal chelating agent for the development of {sup 44}Sc PET imaging agents

Energy Technology Data Exchange (ETDEWEB)

Nagy, Gabor; Szikra, Dezso; Trencsenyi, Gyoergy [Scanomed Ltd., Debrecen (Hungary); University of Debrecen, Medical Imaging Clinic (Hungary); Fekete, Aniko [University of Debrecen, Medical Imaging Clinic (Hungary); Garai, Ildiko [Scanomed Ltd., Debrecen (Hungary); Giani, Arianna M.; Negri, Roberto [Dipartimento di Scienze del Farmaco, Universita del Piemonte Orientale, Novara (Italy); Masciocchi, Norberto [Dipartimento di Scienza e Alta Tecnologia e To.Sca.Lab, Universita degli Studi dell' Insubria, Como (Italy); Maiocchi, Alessandro; Uggeri, Fulvio [Bracco Imaging spa, Bracco Research Centre, Colleretto Giacosa (Italy); Toth, Imre [Department of Inorganic and Analytical Chemistry, University of Debrecen (Hungary); Aime, Silvio [Dipartimento di Biotecnologie Molecolari e Scienze della Salute, Centro di Imaging Molecolare e Preclinico, Universita degli Studi di Torino (Italy); Giovenzana, Giovanni B. [Dipartimento di Scienze del Farmaco, Universita del Piemonte Orientale, Novara (Italy); CAGE Chemicals srl, Novara (Italy); Baranyai, Zsolt [Bracco Imaging spa, Bracco Research Centre, Colleretto Giacosa (Italy); Department of Inorganic and Analytical Chemistry, University of Debrecen (Hungary)

2017-02-13

Unprecedented fast and efficient complexation of Sc{sup III} was demonstrated with the chelating agent AAZTA (AAZTA=1,4-bis(carboxymethyl)-6-[bis(carboxymethyl)] amino-6-methylperhydro-1,4-d iazepine) under mild experimental conditions. The robustness of the {sup 44}Sc(AAZTA){sup -} chelate and conjugated biomolecules thereof is further shown by in vivo PET imaging in healthy and tumor mice models. The new results pave the way towards development of efficient Sc-based radiopharmaceuticals using the AAZTA chelator. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

Mercury removal in utility wet scrubber using a chelating agent

Science.gov (United States)

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.

Optimized molecular reconstruction procedure combining hybrid reverse Monte Carlo and molecular dynamics

Energy Technology Data Exchange (ETDEWEB)

Bousige, Colin; Boţan, Alexandru; Coasne, Benoît, E-mail: coasne@mit.edu [Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139 (United States); UMI 3466 CNRS-MIT, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139 (United States); Ulm, Franz-Josef [Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139 (United States); Pellenq, Roland J.-M. [Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139 (United States); UMI 3466 CNRS-MIT, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139 (United States); CINaM, CNRS/Aix Marseille Université, Campus de Luminy, 13288 Marseille Cedex 09 (France)

2015-03-21

We report an efficient atom-scale reconstruction method that consists of combining the Hybrid Reverse Monte Carlo algorithm (HRMC) with Molecular Dynamics (MD) in the framework of a simulated annealing technique. In the spirit of the experimentally constrained molecular relaxation technique [Biswas et al., Phys. Rev. B 69, 195207 (2004)], this modified procedure offers a refined strategy in the field of reconstruction techniques, with special interest for heterogeneous and disordered solids such as amorphous porous materials. While the HRMC method generates physical structures, thanks to the use of energy penalties, the combination with MD makes the method at least one order of magnitude faster than HRMC simulations to obtain structures of similar quality. Furthermore, in order to ensure the transferability of this technique, we provide rational arguments to select the various input parameters such as the relative weight ω of the energy penalty with respect to the structure optimization. By applying the method to disordered porous carbons, we show that adsorption properties provide data to test the global texture of the reconstructed sample but are only weakly sensitive to the presence of defects. In contrast, the vibrational properties such as the phonon density of states are found to be very sensitive to the local structure of the sample.

Chelation: A Fundamental Mechanism of Action of AGE Inhibitors, AGE Breakers, and Other Inhibitors of Diabetes Complications

Energy Technology Data Exchange (ETDEWEB)

Nagai, Rhoji; Murray, David B.; Metz, Thomas O.; Baynes, John

2012-03-01

Advanced glycation or glycoxidation end-products (AGE) increase in tissue proteins with age, and their rate of accumulation is increased in diabetes, nephropathy and inflammatory diseases. AGE inhibitors include a range of compounds that are proposed to act by trapping carbonyl and dicarbonyl intermediates in AGE formation. However, some among the newer generation of AGE inhibitors lack reactive functional groups that would trap reaction intermediates, indicating an alternative mechanism of action. We propose that AGE inhibitors function primarily as chelators, inhibiting metal-catalyzed oxidation reactions. The AGE-inhibitory activity of angiotensin-converting enzyme inhibitors and angiotensin receptor blockers is also consistent with their chelating activity. Finally, compounds described as AGE breakers, or their hydrolysis products, also have strong chelating activity, suggesting that these compounds also act through their chelating activity. We conclude that chelation is the common, and perhaps the primary, mechanism of action of AGE inhibitors and breakers, and that chronic, mild chelation therapy should prove useful in treatment of diabetes and age-related diseases characterized by oxidative stress, inflammation and increased chemical modification of tissue proteins by advanced glycoxidation and lipoxidation end-products.

Synthesis and physicochemical analysis of Sm (II, III) acetylacetone chelate complexes

International Nuclear Information System (INIS)

Kostyuk, N.N.; Dik, T.A.; Trebnikov, A.G.

2004-01-01

Sm (II, III) acetylacetone chelate complexes were synthesized by electrochemical method. It was shown that anode dissolution of the metal samarium over acetylacetone leads to formation of the Sm (II, III) chelate complexes: xSm(acac)2 · ySm(acac)3 · zH(acac). Factors x, y and z depend on quantity of the electricity, which flew through the electrolysis cell. The compositions of the obtained substances were confirmed by the physicochemical analysis (ultimate analysis, IR-, mass spectroscopy and thermal analysis (thermogravimetric, isothermal warming-up and differential scanning colorimetry). (Authors)

Reversible chemical restraint of free-range cattle with a concentrated combination of tiletamine–zolazepam, ketamine, and detomidine

Science.gov (United States)

Re, Michela; Blanco-Murcia, Francisco J.; San Miguel, José Maria; Gómez de Segura, Ignacio A.

2013-01-01

The aim of this study was to determine the efficacy of a concentrated combination of tiletamine–zolazepam [TZ, 0.53 mg/kg body weight (BW)], ketamine (Ket, 0.53 mg/kg BW), and detomidine (Det, 0.04 mg/kg BW) in the immobilization of free-range cattle for clinical procedures. The combination was administered intramuscularly to 53 animals. Anesthesia was reversed with the α2-adrenoceptor antagonist atipamezole. Locoregional anesthesia was provided with lidocaine when required. The TZKD combination induced suitable immobilization for minor surgical procedures or medical treatments. Anesthetic onset was rapid, taking a mean of 6.1 min [standard deviation (SD) 2.8 min]. The duration of anesthesia depended on the time of administration of the antagonist; the animals recovered in the standing position in 12.9 ± 8.9 min after the administration of atipamezole. The quality of anesthesia and analgesia were satisfactory. In conclusion, this TZKD combination can be used for both immobilization and minor surgical procedures in free-range cattle. PMID:24124271

Reversible chemical restraint of free-range cattle with a concentrated combination of tiletamine-zolazepam, ketamine, and detomidine.

Science.gov (United States)

Re, Michela; Blanco-Murcia, Francisco J; San Miguel, José Maria; Gómez de Segura, Ignacio A

2013-10-01

The aim of this study was to determine the efficacy of a concentrated combination of tiletamine-zolazepam [TZ, 0.53 mg/kg body weight (BW)], ketamine (Ket, 0.53 mg/kg BW), and detomidine (Det, 0.04 mg/kg BW) in the immobilization of free-range cattle for clinical procedures. The combination was administered intramuscularly to 53 animals. Anesthesia was reversed with the α2-adrenoceptor antagonist atipamezole. Locoregional anesthesia was provided with lidocaine when required. The TZKD combination induced suitable immobilization for minor surgical procedures or medical treatments. Anesthetic onset was rapid, taking a mean of 6.1 min [standard deviation (SD) 2.8 min]. The duration of anesthesia depended on the time of administration of the antagonist; the animals recovered in the standing position in 12.9 ± 8.9 min after the administration of atipamezole. The quality of anesthesia and analgesia were satisfactory. In conclusion, this TZKD combination can be used for both immobilization and minor surgical procedures in free-range cattle.

Functionalized dithiocarbamate chelating resin for the removal of Co2+ from simulated wastewater

Science.gov (United States)

Shi, Xuewei; Fu, Linwei; Wu, Yanyang; Zhao, Huiling; Zhao, Shuangliang; Xu, Shouhong

2017-12-01

Industrial wastewater that contains trace amounts of heavy metal ions is often seen in petrochemical industry. While this wastewater can not be directly discharged, it is difficult to treat due to the low concentration of metal ions. Introducing chelating reagents into this wastewater for selective ion adsorption, followed by a mechanical separation process, provides an appealing solution. Toward the success of this technology, the development of effective chelating resins is of key importance. In the present work, a chelating resin containing amino and dithiocarbamate groups was reported for the removal of Co(II) metal ions in trace concentrations from simulated wastewater. By investigating the adsorption performance of the chelating resin at different solution pH values, adsorbent dosages, contact time, initial ion concentrations, and adsorption temperatures, the maximum adsorption capacity of the resin for Co(II) was identified to be 24.89 mg g-1 for a 2 g L-1 adsorbent dosage and a pH value of 5. After four adsorption-desorption cycles, 97% of the adsorption capacity of the resin was maintained. The adsorption kinetics and thermodynamics were analyzed and discussed as well.

New Chelators for Low Temperature Al(18)F-Labeling of Biomolecules.

Science.gov (United States)

Cleeren, Frederik; Lecina, Joan; Billaud, Emilie M F; Ahamed, Muneer; Verbruggen, Alfons; Bormans, Guy M

2016-03-16

The Al(18)F labeling method is a relatively new approach that allows radiofluorination of biomolecules such as peptides and proteins in a one-step procedure and in aqueous solution. However, the chelation of the {Al(18)F}(2+) core with the macrocyclic chelators NOTA or NODA requires heating to 100-120 °C. Therefore, we have developed new polydentate ligands for the complexation of {Al(18)F}(2+) with good radiochemical yields at a temperature of 40 °C. The stability of the new Al(18)F-complexes was tested in phosphate buffered saline (PBS) at pH 7.4 and in rat serum. The stability of the Al(18)F-L3 complex was found to be comparable to that of the previously reported Al(18)F-NODA complex up to 60 min in rat serum. Moreover, the biodistribution of Al(18)F-L3 in healthy mice showed the absence of in vivo defluorination since no significant bone uptake was observed, whereas the major fraction of activity at 60 min p.i. was observed in liver and intestines, indicating hepatobiliary clearance of the radiolabeled ligand. The acyclic chelator H3L3 proved to be a good lead candidate for labeling of heat-sensitive biomolecules with fluorine-18. In order to obtain a better understanding of the different factors influencing the formation and stability of the complex, we carried out more in-depth experiments with ligand H3L3. As a proof of concept, we successfully conjugated the new AlF-chelator with the urea-based PSMA inhibitor Glu-NH-CO-NH-Lys to form Glu-NH-CO-NH-Lys(Ahx)L3, and a biodistribution study in healthy mice was performed with the Al(18)F-labeled construct. This new class of AlF-chelators may have a great impact on PET radiochemical space as it will stimulate the rapid development of new fluorine-18 labeled peptides and other heat-sensitive biomolecules.

Hypothalamic gliosis associated with high-fat diet feeding is reversible in mice: a combined immunohistochemical and magnetic resonance imaging study.

Science.gov (United States)

Berkseth, Kathryn E; Guyenet, Stephan J; Melhorn, Susan J; Lee, Donghoon; Thaler, Joshua P; Schur, Ellen A; Schwartz, Michael W

2014-08-01

Gliosis, the activation of astrocyte and microglial cell populations, is a hallmark of central nervous system injury and is detectable using either immunohistochemistry or in vivo magnetic resonance imaging (MRI). Obesity in rodents and humans is associated with gliosis of the arcuate nucleus, a key hypothalamic region for the regulation of energy homeostasis and adiposity, but whether this response is permanent or reversible is unknown. Here we combine terminal immunohistochemistry analysis with serial, noninvasive MRI to characterize the progression and reversibility of hypothalamic gliosis in high-fat diet (HFD)-fed mice. The effects of HFD feeding for 16 weeks to increase body weight and adiposity relative to chow were nearly normalized after the return to chow feeding for an additional 4 weeks in the diet-reversal group. Mice maintained on the HFD for the full 20-week study period experienced continued weight gain associated with the expected increases of astrocyte and microglial activation in the arcuate nucleus, but these changes were not observed in the diet-reversal group. The proopiomelanocortin neuron number did not differ between groups. Although MRI demonstrated a positive correlation between body weight, adiposity, and the gliosis-associated T2 signal in the mediobasal hypothalamus, it did not detect the reversal of gliosis among the HFD-fed mice after the return to chow diet. We conclude that hypothalamic gliosis associated with 16-week HFD feeding is largely reversible in rodents, consistent with the reversal of the HFD-induced obesity phenotype, and extend published evidence regarding the utility of MRI as a tool for studying obesity-associated hypothalamic gliosis in vivo.

Chelating effect of silver nitrate by chitosan on its toxicity and growth performance in broiler chickens

Directory of Open Access Journals (Sweden)

Yemdjie Mane Divine Doriane

2017-06-01

Full Text Available Objective: This study was conducted to investigate the chelating effect of silver nitrate (AgNO3 by chitosan on growth performances, hematological and biochemical parameters, and the histopathological structure of the liver and the kidney in broiler chicken. Materials and methods: A total of 192 day-old Cobb 500 strain chicks were randomly assigned to 3 treatments of 64 chicks each. Control group was fed on basal diet without supplement (R0 and the two others groups were fed on rations supplemented with 10 mg of unchelated (RAg or chelated (RCs-Ag AgNO3 per Kg of feed, respectively. Parameters that have been studied consisted of feed intake, weight gain, blood and serum biochemical, and histopathological analyses of liver and kidney. Results: Results revealed that chelation of AgNO3 by chitosan did not have any effect on growth performances and hematological parameters in chicken. However, chelated and unchelated AgNO3 increased the serum content in triglyceride, and cholesterol and decreased the serum content in creatinin, albumin and alanine aminotransferase (ALAT. Chelating AgNO3 with chitosan prevented and corrected the toxicity induced on the histological structure of liver and kidney. Conclusion: Chitosan can be used as a chelating agent to alleviate the harmful effects of AgNO3 as silver ion for poultry. [J Adv Vet Anim Res 2017; 4(2.000: 187-193

Chelation technology: a promising green approach for resource management and waste minimization.

Science.gov (United States)

Chauhan, Garima; Pant, K K; Nigam, K D P

2015-01-01

Green chemical engineering recognises the concept of developing innovative environmentally benign technologies to protect human health and ecosystems. In order to explore this concept for minimizing industrial waste and for reducing the environmental impact of hazardous chemicals, new greener approaches need to be adopted for the extraction of heavy metals from industrial waste. In this review, a range of conventional processes and new green approaches employed for metal extraction are discussed in brief. Chelation technology, a modern research trend, has shown its potential to develop sustainable technology for metal extraction from various metal-contaminated sites. However, the interaction mechanism of ligands with metals and the ecotoxicological risk associated with the increased bioavailability of heavy metals due to the formation of metal-chelant complexes is still not sufficiently explicated in the literature. Therefore, a need was felt to provide a comprehensive state-of-the-art review of all aspects associated with chelation technology to promote this process as a green chemical engineering approach. This article elucidates the mechanism and thermodynamics associated with metal-ligand complexation in order to have a better understanding of the metal extraction process. The effects of various process parameters on the formation and stability of complexes have been elaborately discussed with respect to optimizing the chelation efficiency. The non-biodegradable attribute of ligands is another important aspect which is currently of concern. Therefore, biotechnological approaches and computational tools have been assessed in this review to illustrate the possibility of ligand degradation, which will help the readers to look for new environmentally safe mobilizing agents. In addition, emerging trends and opportunities in the field of chelation technology have been summarized and the diverse applicability of chelation technology in metal extraction from

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

Science.gov (United States)

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.

Cancer risk and use of protease inhibitor or nonnucleoside reverse transcriptase inhibitor-based combination antiretroviral therapy: the D: A: D study

NARCIS (Netherlands)

Bruyand, M.; Ryom, L.; Shepherd, L.; Fatkenheuer, G.; Grulich, A.; Reiss, P.; Wit, S. de; Monforte, A.M.; Furrer, H.; Pradier, C.; Lundgren, J.; Sabin, C.; Warris, A.; et al.,

2015-01-01

BACKGROUND: The association between combination antiretroviral therapy (cART) and cancer risk, especially regimens containing protease inhibitors (PIs) or nonnucleoside reverse transcriptase inhibitors (NNRTIs), is unclear. METHODS: Participants were followed from the latest of D:A:D study entry or

Cancer risk and use of protease inhibitor or nonnucleoside reverse transcriptase inhibitor-based combination antiretroviral therapy : the D: A: D study

NARCIS (Netherlands)

Bruyand, Mathias; Ryom, Lene; Shepherd, Leah; Fatkenheuer, Gerd; Grulich, Andrew; Reiss, Peter; de Wit, Stéphane; D Arminio Monforte, Antonella; Furrer, Hansjakob; Pradier, Christian; Lundgren, Jens; Sabin, Caroline; Schölvinck, Elisabeth H.

2015-01-01

BACKGROUND: The association between combination antiretroviral therapy (cART) and cancer risk, especially regimens containing protease inhibitors (PIs) or nonnucleoside reverse transcriptase inhibitors (NNRTIs), is unclear. METHODS: Participants were followed from the latest of D:A:D study entry or

Activation of the CXCR3 chemokine receptor through anchoring of a small molecule chelator ligand between TM-III, -IV, and -VI

DEFF Research Database (Denmark)

Rosenkilde, Mette M; Andersen, Michael B; Nygaard, Rie

2006-01-01

modeling and molecular simulations combined with mutational analysis indicated that the metal ion site-anchored chelators act as agonists by establishing an aromatic-aromatic, second-site interaction with TyrVI:16 on the inner face of TM-VI. It is noteworthy that this interaction required......Seven transmembrane segment (7TM) receptors are activated through a common, still rather unclear molecular mechanism by a variety of chemical messengers ranging from monoamines to large proteins. By introducing a His residue at position III:05 in the CXCR3 receptor a metal ion site was built...... between the extracellular ends of transmembrane (TM) III and TM-IV to anchor aromatic chelators at a location corresponding to the presumed binding pocket for adrenergic receptor agonists. In this construct, free metal ions had no agonistic effect in accordance with the optimal geometry of the metal ion...

Europium(III) chelate-dyed nanoparticles as donors in a homogeneous proximity-based immunoassay for estradiol

International Nuclear Information System (INIS)

Kokko, Leena; Sandberg, Kaisa; Loevgren, Timo; Soukka, Tero

2004-01-01

Nanoparticles containing thousands of fluorescent europium(III) chelates have a very high specific activity compared to traditional lanthanide chelate labels. It can be assumed that if these particles are used in a homogeneous assay as donors, multiple chelates can excite a single acceptor in turns and the energy transfer to the acceptor is increased. The principle was employed in an immunoassay using luminescent resonance energy transfer from a long lifetime europium(III) chelate-dyed nanoparticle to a short lifetime, near-infrared fluorescent molecule. Due to energy transfer fluorescence lifetime of the sensitised emission was prolonged and fluorescence could be measured using a time-resolved detection. A competitive homogeneous immunoassay for estradiol was created using 92 nm europium(III) chelate-dyed nanoparticle coated with 17β-estradiol specific recombinant antibody Fab fragments as a donor and estradiol conjugated with near-infrared dye AlexaFluor 680 as an acceptor. The density of Fab fragments on the surface of the particle influenced the sensitivity of the immunoassay. The optimal Fab density was reached when the entire surface of the particle participated in the energy transfer, but the areas where the energy was transferred to a single acceptor, did not overlap. We were able to detect estradiol concentrations down to 70 pmol l -1 (3xSD of a standard containing 0 nmol l -1 of E2) using a 96-well platform. In this study we demonstrated that nanoparticles containing lanthanide chelates could be used as efficient donors in homogeneous assays

Modelling chelate-Induced phytoextraction: functional models predicting bioavailability of metals in soil, metal uptake and shoot biomass

Directory of Open Access Journals (Sweden)

Pasqualina Sacco

2006-06-01

Full Text Available Chelate-induced phytoextraction of heavy metals from contaminated soils requires special care to determine, a priori, the best method of chelate application, in terms of both dose and timing. In fact, the chelate dose must assure the bioavailability of the metal to the plant without increasing leaching risk and giving toxic effects. Three mathematical models are here proposed for usefully interpreting the processes taking place: a increased soil bioavailability of metals by chelants; b metal uptake by plants; c variation in plant biomass. The models are implemented and validated using data from pot and lysimeter trials. Both the chelate dose and the time elapsed since its application affected metal bioavailability and plant response. Contrariwise, the distribution strategy (single vs. split application seems to produce significant differences both in plant growth and metal uptake, but not in soil metal bioavailability. The proposed models may help to understand and predict the chelate dose – effect relationship with less experimental work.

Modelling chelate-Induced phytoextraction: functional models predicting bioavailability of metals in soil, metal uptake and shoot biomass

Directory of Open Access Journals (Sweden)

Pasqualina Sacco

Full Text Available Chelate-induced phytoextraction of heavy metals from contaminated soils requires special care to determine, a priori, the best method of chelate application, in terms of both dose and timing. In fact, the chelate dose must assure the bioavailability of the metal to the plant without increasing leaching risk and giving toxic effects. Three mathematical models are here proposed for usefully interpreting the processes taking place: a increased soil bioavailability of metals by chelants; b metal uptake by plants; c variation in plant biomass. The models are implemented and validated using data from pot and lysimeter trials. Both the chelate dose and the time elapsed since its application affected metal bioavailability and plant response. Contrariwise, the distribution strategy (single vs. split application seems to produce significant differences both in plant growth and metal uptake, but not in soil metal bioavailability. The proposed models may help to understand and predict the chelate dose – effect relationship with less experimental work.

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

Science.gov (United States)

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.

Microbial screening of thorium(IV) and dioxouranium(VI) chelates with oxine and phenols

International Nuclear Information System (INIS)

Kapadia, M.A.; Patel, M.M.; Patel, G.P.; Joshi, J.D.

2007-01-01

In the present investigation synthesis, characterization of mixed ligand chelates of the type MA 2 L 2 , where, M = Th 4+ and UO 2 2+ , A 8-hydroxyquinoline (oxine) and L = phenols, H2L I = catechol, H 2 L 2 pyrogallol, H 2 L 3 = 2,3-dihydroxy naphthalene, H 2 L 4 = 1,5-dihydroxy naphthalene and H 2 L 5 = 1,7-dihydroxy naphthalene have been reported. Their geometry have been elucidated on the basis of elemental analyses, thermogravimetric, magnetic moments, NMR, IR and electronic spectra. A study of thermal properties has also been carried out. The antimicrobial activity of 8-hydroxyquinoline and MA 2 L 2 chelates have been determined and described. All the chelates showed an effective antimicrobial activity than the free ligand. (author)

Modeling for Colloid and Chelator Facilitated Nuclide Transport in Radioactive Waste Disposal System

International Nuclear Information System (INIS)

Lee, Youn Myoung; Jeong, Jong Tae

2010-08-01

A modeling study and development of a total system performance assessment (TSPA) program template, by which assessment of safety and performance for a radioactive waste repository with normal and/or abnormal nuclide release cases can be made has been developed. Colloid and chelator facilitated transport that is believed to result for faster nuclide transport in various mediabothinthegeosphereandbiospherehas been evaluated deterministically and probabilistically to demonstrate the capability of the template developed through this study. To this end colloid and chelator facilitated nuclide transport has been modeled rather strainghtforwardly with assumed data through this study by utilizing some powerful function offered by GoldSim. An evaluation in view of apparent influence of colloid and chelator on the nuclide transport in the various media in and around a repository system with data assumed are illustrated

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

International Nuclear Information System (INIS)

1991-01-01

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

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

Energy Technology Data Exchange (ETDEWEB)

1991-12-31

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

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

Energy Technology Data Exchange (ETDEWEB)

1991-01-01

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

Removal of cadmium from fish sauce using chelate resin.

Science.gov (United States)

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.

Iron chelates: a challenge to chemists and Moessbauer spectroscopists

Energy Technology Data Exchange (ETDEWEB)

Homonnay, Z., E-mail: homonnay@chem.elte.hu; Szilagyi, P. A.; Vertes, A. [Eoetvoes Lorand University, Laboratory of Nuclear Chemistry, Institute of Chemistry (Hungary); Kuzmann, E. [Hungarian Academy of Sciences, Department of Nuclear Chemistry, Chemical Research Center (Hungary); Sharma, V. K. [Florida Institute of Technology (United States); Molnar, G.; Bousseksou, A. [CNRS UPR-8241, Laboratoire de Chimie de Coordination (France); Greneche, J.-M. [Universite du Maine, Laboratoire de Physique de l' Etat Condense, CNRS UMR 6087 (France); Brausam, A.; Meier, R.; Eldik, R. van [University of Erlangen-Nuernberg, Institute for Inorganic Chemistry (Germany)

2008-02-15

The speciation of iron in aqueous solutions containing Fe{sup 3+} and selected chelates such as EDTA, EDDA, CDTA and HEDTA has been studied using transmission {sup 57}Fe Moessbauer spectrometry in frozen solutions. The protonation of various complexes as well as binuclear complex formation could be detected as a function of pH. Autoreduction of Fe{sup 3+} to Fe{sup 2+} was observed in several cases. Reaction with hydrogen peroxide proved to be rather different for the four ligands, while the dihapto complex [XFe({eta}{sup 2}-O{sub 2})]{sup 3-} had surprisingly identical Moessbauer parameters for X = EDTA, CDTA or HEDTA. Paramagnetic spin relaxation observed in the Moessbauer spectra was found to be strongly influenced by the identity of the chelating ligand, despite the basically spin-spin origin of the phenomenon.

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

International Nuclear Information System (INIS)

Lafuma, J.; Nenot, J.C.; Morin, M.

1968-01-01

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

KINETICS OF THE OXIDATION OF FERROUS CHELATES OF EDTA AND HEDTA IN AQUEOUS-SOLUTION

NARCIS (Netherlands)

WUBS, HJ; BEENACKERS, AACM

1993-01-01

The kinetics of the reaction of oxygen with ferrous chelates of EDTA and HEDTA was studied in a stirred cell reactor under industrial conditions. The temperature was varied from 20 to 60-degrees-C and the concentration of the ferrous chelate ranged from 0 to 100 mol/m3. The initial pH was 7.5. Under

Synthesis and evaluation of hydroxamamide-based tetradentate ligands as a new class of thiol-free chelating molecules for 99mTc radiopharmaceuticals.

Science.gov (United States)

Xu, L C; Nakayama, M; Harada, K; Nakayama, H; Tomiguchi, S; Kojima, A; Takahashi, M; Arano, Y

1998-04-01

Both N,N'-ethylene bis(benzohydroxamamide) [(C2(BHam)2)] and N,N'-propylene bis(benzohydroxamamide) [(C3(BHam)2)] were designed as new thiol-free chelating molecules for 99mTc radiopharmaceuticals. Synthetic procedures using oxadiazoline intermediates were developed for C2(BHam)2 and C3(BHam)2. Both C2(BHam)2 and C3(BHam)2 formed 99mTc complexes with high yields over a wide pH range (pH 3-12) at room temperature. Complexation yields of over 95% were achieved at ligand concentrations as low as 2.5 x 10(-6) M. Reversed-phase HPLC analyses indicated that both C2(BHam)2 and C3(BHam)2 formed 99mTc complexes as single species with stabilities much higher than those of 99mTc-BHam. Selective complex formation of 99mTc with the two ligands was observed in the presence of human IgG. No decomposition with low protein binding were demonstrated when the two 99mTc complexes were incubated in murine plasma. Although further structural studies are required, these findings implied that the Ham-based tetradentate ligands would serve as new chelating molecules for 99mTc radiopharmaceuticals.

Synthesis and evaluation of hydroxamamide-based tetradentate ligands as a new class of thiol-free chelating molecules for 99mTc radiopharmaceuticals

International Nuclear Information System (INIS)

Xu Lecun; Nakayama, Morio; Harada, Kumiko; Nakayama, Hitoshi; Tomiguchi, Seiji; Kojima, Akihiro; Takahashi, Mutsumasa; Arano, Yasushi

1998-01-01

Both N,N'-ethylene bis(benzohydroxamamide) [(C 2 (BHam) 2 )] and N,N'-propylene bis(benzohydroxamamide) [(C 3 (BHam) 2 )] were designed as new thiol-free chelating molecules for 99m Tc radiopharmaceuticals. Synthetic procedures using oxadiazoline intermediates were developed for C 2 (BHam) 2 and C 3 (BHam) 2 . Both C 2 (BHam) 2 and C 3 (BHam) 2 formed 99m Tc complexes with high yields over a wide pH range (pH 3-12) at room temperature. Complexation yields of over 95% were achieved at ligand concentrations as low as 2.5 x 10 -6 M. Reversed-phase HPLC analyses indicated that both C 2 (BHam) 2 and C 3 (BHam) 2 formed 99m Tc complexes as single species with stabilities much higher than those of 99m Tc-BHam. Selective complex formation of 99m Tc with the two ligands was observed in the presence of human IgG. No decomposition with low protein binding were demonstrated when the two 99m Tc complexes were incubated in murine plasma. Although further structural studies are required, these findings implied that the Ham-based tetradentate ligands would serve as new chelating molecules for 99m Tc radiopharmaceuticals

Comparing soluble ferric pyrophosphate to common iron salts and chelates as sources of bioavailable iron in a Caco-2 cell culture model.

Science.gov (United States)

Zhu, Le; Glahn, Raymond P; Nelson, Deanna; Miller, Dennis D

2009-06-10

Iron bioavailability from supplements and fortificants varies depending upon the form of the iron and the presence or absence of iron absorption enhancers and inhibitors. Our objectives were to compare the effects of pH and selected enhancers and inhibitors and food matrices on the bioavailability of iron in soluble ferric pyrophosphate (SFP) to other iron fortificants using a Caco-2 cell culture model with or without the combination of in vitro digestion. Ferritin formation was the highest in cells treated with SFP compared to those treated with other iron compounds or chelates. Exposure to pH 2 followed by adjustment to pH 7 markedly decreased FeSO(4) bioavailability but had a smaller effect on bioavailabilities from SFP and sodium iron(III) ethylenediaminetetraacetate (NaFeEDTA), suggesting that chelating agents minimize the effects of pH on iron bioavailability. Adding ascorbic acid (AA) and cysteine to SFP in a 20:1 molar ratio increased ferritin formation by 3- and 2-fold, respectively, whereas adding citrate had no significant effect on the bioavailability of SFP. Adding phytic acid (10:1) and tannic acid (1:1) to iron decreased iron bioavailability from SFP by 91 and 99%, respectively. The addition of zinc had a marked inhibitory effect on iron bioavailability. Calcium and magnesium also inhibited iron bioavailability but to a lesser extent. Incorporating SFP in rice greatly reduced iron bioavailability from SFP, but this effect can be partially reversed with the addition of AA. SFP and FeSO(4) were taken up similarly when added to nonfat dry milk. Our results suggest that dietary factors known to enhance and inhibit iron bioavailability from various iron sources affect iron bioavailability from SFP in similar directions. However, the magnitude of the effects of iron absorption inhibitors on SFP iron appears to be smaller than on iron salts, such as FeSO(4) and FeCl(3). This supports the hypothesis that SFP is a promising iron source for food fortification

Extrafibrillar collagen demineralization-based chelate-and-rinse technique bridges the gap between wet and dry dentin bonding.

Science.gov (United States)

Mai, Sui; Wei, Chin-Chuan; Gu, Li-Sha; Tian, Fu-Cong; Arola, Dwayne D; Chen, Ji-Hua; Jiao, Yang; Pashley, David H; Niu, Li-Na; Tay, Franklin R

2017-07-15

Limitations associated with wet-bonding led to the recent development of a selective demineralization strategy in which dentin was etched with a reduced concentration of phosphoric acid to create exclusive extrafibrillar demineralization of the collagen matrix. However, the use of acidic conditioners removes calcium via diffusion of very small hydronium ions into the intrafibrillar collagen water compartments. This defeats the purpose of limiting the conditioner to the extrafibrillar space to create a collagen matrix containing only intrafibrillar minerals to prevent collapse of the collagen matrix. The present work examined the use of polymeric chelators (the sodium salt of polyacrylic acid) of different molecular weights to selectively demineralize extrafibrillar dentin. These polymeric chelators exhibit different affinities for calcium ions (isothermal titration calorimetry), penetrated intrafibrillar dentin collagen to different extents based on their molecular sizes (modified size-exclusion chromatography), and preserve the dynamic mechanical properties of mineralized dentin more favorably compared with completely demineralized phosphoric acid-etched dentin (nanoscopical dynamic mechanical analysis). Scanning and transmission electron microscopy provided evidence for retention of intrafibrillar minerals in dentin surfaces conditioned with polymeric chelators. Microtensile bond strengths to wet-bonded and dry-bonded dentin conditioned with these polymeric chelators showed that the use of sodium salts of polyacrylic acid for chelating dentin prior to bonding did not result in significant decline in resin-dentin bond strength. Taken together, the findings led to the conclusion that a chelate-and-rinse conditioning technique based on extrafibrillar collagen demineralization bridges the gap between wet and dry dentin bonding. The chelate-and-rinse dental adhesive bonding concept differentiates from previous research in that it is based on the size

Iron overload and chelation therapy in myelodysplastic syndromes.

Science.gov (United States)

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

2014-07-01

Iron overload remains a concern in MDS patients especially those requiring recurrent blood transfusions. The consequence of iron overload may be more relevant in patients with low and intermediate-1 risk MDS who may survive long enough to experience such manifestations. It is a matter of debate whether this overload has time to yield organ damage, but it is quite evident that cellular damage and DNA genotoxic effect are induced. Iron overload may play a critical role in exacerbating pre-existing morbidity or even unmask silent ones. Under these circumstances, iron chelation therapy could play an integral role in the management of these patients. This review entails an in depth analysis of iron overload in MDS patients; its pathophysiology, effect on survival, associated risks and diagnostic options. It also discusses management options in relation to chelation therapy used in MDS patients and the impact it has on survival, hematologic response and organ function. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Molecular characterization of whey protein hydrolysate fractions with ferrous chelating and enhanced iron solubility capabilities.

Science.gov (United States)

O'Loughlin, Ian B; Kelly, Phil M; Murray, Brian A; FitzGerald, Richard J; Brodkorb, Andre

2015-03-18

The ferrous (Fe2+) chelating capabilities of WPI hydrolysate fractions produced via cascade membrane filtration were investigated, specifically 1 kDa permeate (P) and 30 kDa retentate (R) fractions. The 1 kDa-P possessed a Fe2+ chelating capability at 1 g L(-1) equivalent to 84.4 μM EDTA (for 30 kDa-R the value was 8.7 μM EDTA). Fourier transformed infrared (FTIR) spectroscopy was utilized to investigate the structural characteristics of hydrolysates and molecular interactions with Fe2+. Solid-phase extraction was employed to enrich for chelating activity; the most potent chelating fraction was enriched in histidine and lysine. The solubility of ferrous sulfate solutions (10 mM) over a range of pH values was significantly (Piron solubility was improved by 72% in the presence of the 1 kDa-P fraction following simulated gastrointestinal digestion (SGID) compared to control FeSO4·7H2O solutions.

Bifunctional chelating agent for the design and development of site specific radiopharmaceuticals and biomolecule conjugation strategy

Science.gov (United States)

Katti, Kattesh V.; Prabhu, Kandikere R.; Gali, Hariprasad; Pillarsetty, Nagavara Kishore; Volkert, Wynn A.

2003-10-21

There is provided a method of labeling a biomolecule with a transition metal or radiometal in a site specific manner to produce a diagnostic or therapeutic pharmaceutical compound by synthesizing a P.sub.2 N.sub.2 -bifunctional chelating agent intermediate, complexing the intermediate with a radio metal or a transition metal, and covalently linking the resulting metal-complexed bifunctional chelating agent with a biomolecule in a site specific manner. Also provided is a method of synthesizing the --PR.sub.2 containing biomolecules by synthesizing a P.sub.2 N.sub.2 -bifunctional chelating agent intermediate, complexing the intermediate with a radiometal or a transition metal, and covalently linking the resulting radio metal-complexed bifunctional chelating agent with a biomolecule in a site specific manner. There is provided a therapeutic or diagnostic agent comprising a --PR.sub.2 containing biomolecule.

Heavy Metal Displacement in Chelate-Assisted Phytoremediation of Biosolids Soil

Science.gov (United States)

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

Chelate-Modified Fenton Reaction for the Degradation of Trichloroethylene in Aqueous and Two-Phase Systems

Energy Technology Data Exchange (ETDEWEB)

Lewis, Scott [Univ of KY, dept of chemical and materials engineering; lynch, Andrew [Univ of KY, dept of chemical and materials engineering; Bachas, Leonidas [Univ of KY, Dept of Chemistry; hampson, Steve [Univ of KY Center for Applied Energy Research - KY Research Consortium of Energy and Environment; Ormsbee, Lindelle [Univ of KY Center for Applied Energy Research - KY Research Consortium of Energy and Environment; Bhattacharyya, Dibakar [Univ of KY, dept of chemical and materials engineering

2008-06-01

The Standard Fenton reaction has been used for In-Situ Chemical Oxidation (ISCO) of toxic organics in groundwater. However, it requires low pH operating conditions, and thus has limitations for in situ applications. In addition, hydroxyl radicals are rapidly consumed by hydroxyl scavengers found in the subsurface. These problems are alleviated through the chelate-modified Fenton (hydroxyl radical) reaction, which includes the addition of nontoxic chelate (L) such as citrate or gluconic acid. This chelate allows the reaction to take place at bear neutral pH and control hydrogen peroxide consumption by binding to Fe(II), forming an FeL complex. The chelate also binds to Fe(III), preventing its precipitation as ferric hydroxide and thus prevents problems associated with injection well plugging. The rate of TCE dechlorination in chelate-modified Fenton systems is a function of pH, H2O2 concentration, and FE:L ratio. The primary objective of this research is to model and apply this process to the destruction of trichloroethylene (TCE) present in both the aqueous and organic (in the form of droplets) phases. Experimentation proved the chelate-modified Fenton reaction effectively dechlorinates TCE in both the aqueous and organic phases at near-neutral pH. Other focuses of this work include determining the effect of [L]:[Fe] ratios on H2O2 and TCE degradation as well as reusability of the FE citrate solution under repeated H2O2 injections. Generalized models were developed to predict the concentration of TCE in the aqueous phase and TCE droplet radius as a function of time using established hydroxyl radial kinetics and mass transfer relationships.

Effects of intracellular chelatable iron and oxidative stress on transcription of classical cellular glutathione peroxidase gene in murine erythroleukemia cells

International Nuclear Information System (INIS)

Fuchs, O.

1997-01-01

The effect of intracellular chelatable iron levels and of oxidative stress on nuclear classical cellular glutathione peroxidase (GSHPx-1) RNA nascent chain elongation (run-on transcription) and on the stability of cytoplasmic GSHPx-1 mRNA was investigated in murine erythroleukemia (MEL) cells. The amount in the intracellular low molecular mass iron pool was changed by incubation of MEL cells transformed by Friend virus with iron donors or iron chelators. Transcription in vitro in isolated nuclei from treated cells showed that the treatment with chelators (desferrioxamine (DFO), pyridoxal isonicotinoyl hydrazone) decrease the rate of nuclear GSHPx-1 RNA nascent chain elongation in both un-induced and with 5 mmol hexamethylenebisacetamide to erythroid differentiation induced MEL cells. Iron donors (diferric transferrin,, Fe-PIH or their combination) and t-butyl hydroperoxide (t-BuOOH) had the opposite effect on GSHPx-1 gene transcription in run-on experiments. On the other hand, 50 μmol DFO or 2.5 μmol t-BuOOH did not change the stability of cytoplasmic GSHPx-1 mRNA in both un-induced and induced MEL cells treated with 5 μmol actinomycin D and with or without these agents for 9 h. These findings indicate that iron and oxidative stress play their role at the transcriptional level of GSHPx-1 gene expression. (author)

MiADMSA reverses impaired mitochondrial energy metabolism and neuronal apoptotic cell death after arsenic exposure in rats

Energy Technology Data Exchange (ETDEWEB)

Dwivedi, Nidhi; Mehta, Ashish; Yadav, Abhishek [Division of Pharmacology and Toxicology, Defence Research and Development Establishment, Gwalior-474 002 (India); Binukumar, B.K.; Gill, Kiran Dip [Department of Biochemistry, Postgraduate Institute of Medical Education and Research, Chandigarh-160 012 (India); Flora, Swaran J.S., E-mail: sjsflora@hotmail.com [Division of Pharmacology and Toxicology, Defence Research and Development Establishment, Gwalior-474 002 (India)

2011-11-15

Arsenicosis, due to contaminated drinking water, is a serious health hazard in terms of morbidity and mortality. Arsenic induced free radicals generated are known to cause cellular apoptosis through mitochondrial driven pathway. In the present study, we investigated the effect of arsenic interactions with various complexes of the electron transport chain and attempted to evaluate if there was any complex preference of arsenic that could trigger apoptosis. We also evaluated if chelation with monoisoamyl dimercaptosuccinic acid (MiADMSA) could reverse these detrimental effects. Our results indicate that arsenic exposure induced free radical generation in rat neuronal cells, which diminished mitochondrial potential and enzyme activities of all the complexes of the electron transport chain. Moreover, these complexes showed differential responses towards arsenic. These early events along with diminished ATP levels could be co-related with the later events of cytosolic migration of cytochrome c, altered bax/bcl{sub 2} ratio, and increased caspase 3 activity. Although MiADMSA could reverse most of these arsenic-induced altered variables to various extents, DNA damage remained unaffected. Our study for the first time demonstrates the differential effect of arsenic on the complexes leading to deficits in bioenergetics leading to apoptosis in rat brain. However, more in depth studies are warranted for better understanding of arsenic interactions with the mitochondria. -- Research highlights: Black-Right-Pointing-Pointer Arsenic impairs mitochondrial energy metabolism leading to neuronal apoptosis. Black-Right-Pointing-Pointer Arsenic differentially affects mitochondrial complexes, I - III and IV being more sensitive than complex II. Black-Right-Pointing-Pointer Arsenic-induced apoptosis initiates through ROS generation or impaired [Ca{sup 2+}]i homeostasis. Black-Right-Pointing-Pointer MiADMSA reverses arsenic toxicity via intracellular arsenic- chelation, antioxidant

Hepatobiliary delivery of polyaminopolycarboxylate chelates: Synthesis and characterization of a cholic acid conjugate of EDTA and biodistribution and imaging studies with its indium-111 chelate

Energy Technology Data Exchange (ETDEWEB)

Betebenner, D.A.; Carney, P.L.; Zimmer, A.M.; Kazikiewicz, J.M.; Bruecher, E.S.; Sherry, A.D.; Johnson, D.K. (Abbott Laboratories, Abbott Park, Illinois (USA))

1991-03-01

A conjugate in which the steroid nucleus of cholic acid was linked to EDTA via an 11-atom spacer was obtained by reacting the succinimidyl ester of cholic acid with the amine formed by reaction of a benzyl isothiocyanate derivative of EDTA with N-(tert-butoxycarbonyl)ethylenediamine and subsequent deprotection. Potentiometric titration studies with model complexes showed that the EDTA moiety retained the ability to form 1:1 chelates of high thermodynamic stability, although formation constants were some 3-4 log K units lower for complexes of the conjugate than for the analogous chelates with underivatized EDTA. A complex formed between the cholic acid-EDTA conjugate and 111InIII was clearly rapidly into the liver when injected iv into mice, with subsequent excretion from the liver into the gastrointestinal tract being complete within 1 h of injection. Radioscintigraphic imaging studies conducted in a rabbit given the 111In-labeled conjugate also showed early liver uptake followed by rapid clearance from the liver into the intestine, with good visualization of the gallbladder in images obtained at 20-25 min postinjection. It is concluded that conjugation to cholic acid provides a useful means for the hepatobiliary delivery of EDTA chelates that otherwise exhibit predominantly extracellular distribution and renal clearance.

Hepatobiliary delivery of polyaminopolycarboxylate chelates: Synthesis and characterization of a cholic acid conjugate of EDTA and biodistribution and imaging studies with its indium-111 chelate

International Nuclear Information System (INIS)

Betebenner, D.A.; Carney, P.L.; Zimmer, A.M.; Kazikiewicz, J.M.; Bruecher, E.S.; Sherry, A.D.; Johnson, D.K.

1991-01-01

A conjugate in which the steroid nucleus of cholic acid was linked to EDTA via an 11-atom spacer was obtained by reacting the succinimidyl ester of cholic acid with the amine formed by reaction of a benzyl isothiocyanate derivative of EDTA with N-(tert-butoxycarbonyl)ethylenediamine and subsequent deprotection. Potentiometric titration studies with model complexes showed that the EDTA moiety retained the ability to form 1:1 chelates of high thermodynamic stability, although formation constants were some 3-4 log K units lower for complexes of the conjugate than for the analogous chelates with underivatized EDTA. A complex formed between the cholic acid-EDTA conjugate and 111InIII was clearly rapidly into the liver when injected iv into mice, with subsequent excretion from the liver into the gastrointestinal tract being complete within 1 h of injection. Radioscintigraphic imaging studies conducted in a rabbit given the 111In-labeled conjugate also showed early liver uptake followed by rapid clearance from the liver into the intestine, with good visualization of the gallbladder in images obtained at 20-25 min postinjection. It is concluded that conjugation to cholic acid provides a useful means for the hepatobiliary delivery of EDTA chelates that otherwise exhibit predominantly extracellular distribution and renal clearance

Iron overload of organism and current options of chelation treatment in onco haematology

International Nuclear Information System (INIS)

Guman, T.; Rothova, E.; Kafkova, A.; Fricova, M.; Dulova, I.; Stecova, N.; Hlebaskova, M.; Surova, M.; Takac, V.

2011-01-01

The article summarizes the biological importance of iron in the organism, primary and secondary causes of iron overload, complications in function of liver, heart and endocrine organs due to overload of iron, the pathophysiology of iron overload, transfusion risks associated with the iron overload, assessment of risk groups of patients suitable for chelation treatment fulfilling the indication criteria, treatment modalities of chelation therapy and its significance regarding the prevention and treatment effectiveness. (author)

Effective sulfur and energy recovery from hydrogen sulfide through incorporating an air-cathode fuel cell into chelated-iron process.

Science.gov (United States)

Sun, Min; Song, Wei; Zhai, Lin-Feng; Cui, Yu-Zhi

2013-12-15

The chelated-iron process is among the most promising techniques for the hydrogen sulfide (H2S) removal due to its double advantage of waste minimization and resource recovery. However, this technology has encountered the problem of chelate degradation which made it difficult to ensure reliable and economical operation. This work aims to develop a novel fuel-cell-assisted chelated-iron process which employs an air-cathode fuel cell for the catalyst regeneration. By using such a process, sulfur and electricity were effectively recovered from H2S and the problem of chelate degradation was well controlled. Experiment on a synthetic sulfide solution showed the fuel-cell-assisted chelated-iron process could maintain high sulfur recovery efficiencies generally above 90.0%. The EDTA was preferable to NTA as the chelating agent for electricity generation, given the Coulombic efficiencies (CEs) of 17.8 ± 0.5% to 75.1 ± 0.5% for the EDTA-chelated process versus 9.6 ± 0.8% to 51.1 ± 2.7% for the NTA-chelated process in the pH range of 4.0-10.0. The Fe (III)/S(2-) ratio exhibited notable influence on the electricity generation, with the CEs improved by more than 25% as the Fe (III)/S(2-) molar ratio increased from 2.5:1 to 3.5:1. Application of this novel process in treating a H2S-containing biogas stream achieved 99% of H2S removal efficiency, 78% of sulfur recovery efficiency, and 78.6% of energy recovery efficiency, suggesting the fuel-cell-assisted chelated-iron process was effective to remove the H2S from gas streams with favorable sulfur and energy recovery efficiencies. Copyright © 2013 Elsevier B.V. All rights reserved.

Impact of educational programme regarding chelation therapy on the quality of life for B-thalassemia major children.

Science.gov (United States)

Abu Samra, Omayma; Auda, Wafaa; Kamhawy, Heba; Al-Tonbary, Youssef

2015-06-01

Objectives Thalassemia is the most common genetic disorder in Egypt, with an estimated carrier rate of 9-10%. It is a genetic blood disorder which can be fatal if proper chelation is not received. The introduction of chelating agents capable of removing excessive iron from the body has dramatically increased life expectancy and improved the overall quality of life. The aim of this study was to assess the impact of educational programmes regarding chelation therapy on the quality of life of thalassemic children. Methods The study was carried out at the Mansoura University Children's Hospital in the period between March 2010 and May 2011. It included 173 B-thalassemia children (84 boys and 89 girls) with age ranging between 8-18 years. The researcher used a predesigned interviewing questionnaire to collect data regarding children's knowledge about thalassemia and its management, especially regarding chelation therapy. The paediatric quality-of-life inventory tool (Peds QL 4.0 generic core) was also used to assess the studied children's quality of life. Results There was a significant statistical difference of the studied children's knowledge regarding chelation therapy and their quality of life. Conclusion There was a positive effect of the educational programme in improving children's knowledge score and their quality of life. Application of educational programmes for thalassemic children and their nurses regarding chelation therapy and its importance in preventing thalassemia complications is established.

Zn availability in nutrient solutions for cucumber (Cucumis sativus L) in hydroponics as affected by Fe-chelates and pH

NARCIS (Netherlands)

Voogt, W.; Sonneveld, C.

2017-01-01

In soil-less culture systems Fe is usually supplied as chelate to ensure an adequate availability of this element. As chelates have affinity for many metal ions these chelates will interact with other cation nutrients in nutrient solutions. This affects the availability of Fe and other nutrients.

Comparative studies of 111In-labeled monoclonal antibody using spacer-containing and non-spacer bifunctional chelates. 2

International Nuclear Information System (INIS)

Sun, Baofu

1994-01-01

Indium-111-labeled A7 monoclonal antibodies using two spacer-containing chelates, succinimido-EGS-DTPA (EGS-DTPA: diester spacer) and maleimido-C10-Bz-EDTA (C10-Bz-EDTA: hydrocarbon spacer) were investigated in human LS180 colon tumor bearing nude mice and were compared with two non-spacer chelates, cyclic DTPA dianhydride (cDTPAA) and isothiocyanatobenzyl-EDTA (SCN-Bz-EDTA). Compared with immunoconjugates using non-spacer chelates, immunoconjugates using spacer-containing chelates, especially C10-Bz-EDTA-A7 showed lower 111 In activity in normal organs. The radioactivity in the liver for C10-Bz-EDTA-A7 decreased continuously till 96 hrs postinjection, however, this liver radioactivity for EGS-DTPA-A7 showed little change after 24 hrs. Moreover, in liver subcellular distribution study, EGS-DTPA-A7 showed a higher activity retention in mitochondrial fraction which contained lysosome, a place for metabolizing and storing of 111 In labeled antibody, than that of C10-Bz-EDTA-A7. The C10-Bz-EDTA-A7 conjugate demonstrated more preferable tumor-to-non tumor contrast on the scintigrams than that found with other three immunoconjugates. Up to 96 hrs postinjection, tumor bearing nude mice injecting with immunoconjugates using spacer-containing chelates exreted twice radioactivity from whole body than that excreted by using non-spacer chelates. Interestingly, different from other three chelates, C10-Bz-EDTA-A7 were mainly excreted via feces. We conclude that the decrease of radioactivity in normal tissues in the case of EGS-DTPA-A7 was due to the rapid decrease of activity in the blood, while in the case of C10-Bz-EDTA-A7 it was due to the quickly excreted small metabolite through faces. 111 In labeled C10-Bz-EDTA conjugate is superior, at least when conjugated with A7, to other three chelate conjugates used in this study. (author)

Leach studies of chelating agents and influence on radionuclide leaching from simulated LLW/ILW cement waste forms

International Nuclear Information System (INIS)

Vejmelka, P.; Koester, R.; Ferrara, D.; Wacks, M.E.

1990-01-01

Leach studies were performed on cemented waste forms containing sodium nitrate, trace amounts of cesium-137, and cobalt-60, and a chelating agent (ethylene diamine tetraacetic acid (EDTA), nitrilotriacetic acid (NTA), or citric acid). Leaching of the chelates was measured in water and the effect of the chelates on the release of the Cs-137 and Co-60 was studied. The time dependence of the release rate of the chelates is comparable but the chelate concentration in solution and the released fractions are different. EDTA shows the highest release rate followed by NTA and citrate. The release of the non complex forming cesium is not affected by the presence of the chelates. Independent from the strong complex formation of cobalt with EDTA, NTA, and citrate in the alkaline region the cobalt release is also not affected by the presence of the chelates. The high calcium content of the system decreases the stability of the Co complexes in the high pH region (12-13). Experiments were performed to determine the equilibrium concentration of the chelates between liquid and solid phases. The liquid phases were deionized water, saturated sodium chloride, 24 percent magnesium chloride and Q-brine. The equilibrium studies are based on the assumption that in time a stable final condition is to be established in the near field of the waste form in which each compound is at chemical equilibrium between the dissolved and the various solid phases. The total release may be assessed from the concentration in solution and flow rate out of the near field. The fraction of EDTA released from the cement ranged from 0.2 in the Q-brine to 0.5 in the saturated sodium chloride. The concentration of EDSA in solution was dependent on the original amount in the cement sample, but the released fraction was independent of the initial loading. Indicating, EDTA concentration is not affected by solubility limits. 11 refs., 3 figs., 2 tabs

MULTIDENTATE TEREPHTHALAMIDATE AND HYDROXYPYRIDONATE LIGANDS: TOWARDS NEW ORALLY ACTIVE CHELATORS

Energy Technology Data Exchange (ETDEWEB)

Abergel, Rebecca J.; Raymond, Kenneth N.

2011-07-13

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

Metal chelates of some transition and non-transition metal ions with Schiff base derived from isatin with o-phenylenediamine

International Nuclear Information System (INIS)

Hassaan, A.M.A.; Khalifa, M.A.

1993-01-01

New Cr(III), Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), and Pb(II) chelates of the Schiff base derived from isatin with o-phenylenediamine have been synthesized and characterized on the basis of elemental analyses, electronic, IR and 1 H NMR spectra, and also by aid of molar conductivity and magnetic moment measurements. It has been found that the Schiff base behaves as ONNO tetradentate dibasic ligand forming chelates with 1:1 (metal:ligand) stoichiometry. Square planar environment is suggested for nickel(II) chelate. All the metal chelates show non-electrolytic behaviour

Benzimidazolyl methyliminodiacetic acids: new bifunctional chelators of technetium for hepatobiliary scintigraphy

International Nuclear Information System (INIS)

Hunt, F.C.; Wilson, J.G.; Maddalena, D.J.

1979-01-01

Dimethyl- and chloro- substituted benzimidazolyl methyliminodiacetic acids have been synthesized and evaluated as new bifunctional chelators of /sup 99m/Tc. Stannous chelates of these compounds were prepared as freeze-dried kits and labeled with /sup 99m/Tc. The radiopharmaceuticals thus prepared were rapidly excreted by the hepatobiliary system of rats and rabbits with little urinary excretion. The chloro- compound had a higher biliary and lesser urinary excretion than the dimethyl- however both technetium complexes provided good scintigraphic images of the hepatobiliary system in animals. The compounds behaved similarly to the /sup 99m/Tc-lidocaine iminodiacetic acid [HIDA] complexes with respect to their biliary elimination

Polymeric metal chelates with piperazine(bis)dithiocarbamate

International Nuclear Information System (INIS)

Larionov, S.V.; Kosareva, L.A.; Ikorskij, V.N.; Uskov, E.M.

1982-01-01

Roentgenoamorphous polymer chelates of Fe 3 , Co 2 , Ni 2 , Cu 2 , Zn 2 , Cd 2 , Pb 2 with tetradentate bridge ligand piperazine-(bis) dithiocarbamate have been synthesized. IR spectra in the region 200-400 cm - 1 point to coordination of sulphur atoms of groups CS 2- with metals. It is found that among the polymers synthesized CuLxH 2 O possesses the lowest electric resistance

Repurposing of Copper(II)-chelating Drugs for the Treatment of Neurodegenerative Diseases.

Science.gov (United States)

Lanza, Valeria; Milardi, Danilo; Di Natale, Giuseppe; Pappalardo, Giuseppe

2018-02-12

There is mounting urgency to find new drugs for the treatment of neurodegenerative disorders. A large number of reviews have exhaustively described either the molecular or clinical aspects of neurodegenerative diseases such as Alzheimer's (AD) and Parkinson's (PD). Conversely, reports outlining how known drugs in use for other diseases can also be effective as therapeutic agents in neurodegenerative diseases are less reported. This review focuses on the current uses of some copper(II) chelating molecules as potential drug candidates in neurodegeneration. Starting from the well-known harmful relationships existing between the dyshomeostasis and mis-management of metals and AD onset, we surveyed the experimental work reported in the literature, which deals with the repositioning of metal-chelating drugs in the field of neurodegenerative diseases. The reviewed papers were retrieved from common literature and their selection was limited to those describing the biomolecular aspects associated with neuroprotection. In particular, we emphasized the copper(II) coordination abilities of the selected drugs. Copper, together with zinc and iron, are known to play a key role in regulating neuronal functions. Changes in copper homeostasis are crucial for several neurodegenerative disorders. The studies included in this review may provide an overview on the current strategies aimed at repurposing copper (II) chelating drugs for the treatment of neurodegenerative disorders. Starting from the exemplary case of clioquinol repurposing, we discuss the challenge and the opportunities that repurposing of other metal-chelating drugs may provide (e.g. PBT-2, metformin and cyclodipeptides) in the treatment of neurodegenerative disease. In order to improve the success rate of drug repositioning, comprehensive studies on the molecular mechanism and therapeutic efficacy are still required. The present review upholds that drug repurposing makes significant advantages over drug discovery since

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

Science.gov (United States)

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 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-labeled immunoconjugates was 100%+/-11%. The optimization of 90Y-DOTA chelation conditions represents an important advance in 90Y RIT

Antibacterial and antibiofilm effects of iron chelators against Prevotella intermedia.

Science.gov (United States)

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

2013-09-01

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

A randomized trial comparing initial HAART regimens of nelfinavir/nevirapine and ritonavir/saquinavir in combination with two nucleoside reverse transcriptase inhibitors

DEFF Research Database (Denmark)

Kirk, Ole; Lundgren, Jens D; Pedersen, Court

2003-01-01

BACKGROUND: A triple-class HAART regimen may be associated with a better virological effect than conventional regimens, but may also lead to toxicity and more profound resistance. METHODS: Randomized, controlled, open-label trial of 233 protease inhibitor- and non-nucleoside reverse transcriptase...... inhibitor-naive HIV-infected patients allocated to a regimen of nelfinavir and nevirapine (1250/200 mg twice daily; n = 118) or ritonavir and saquinavir (400/400 mg twice daily; n = 115), both in combination with two nucleoside reverse transcriptase inhibitors. The primary end-point was HIV RNA ... the long-term consequences of triple class HAART regimens, including the development of broad drug resistance....

Effect of disodium EDTA chelation regimen on cardiovascular events in patients with previous myocardial infarction: the TACT randomized trial.

Science.gov (United States)

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

2013-03-27

Chelation therapy with disodium EDTA has been used for more than 50 years to treat atherosclerosis without proof of efficacy. To determine if an EDTA-based chelation regimen reduces cardiovascular events. Double-blind, placebo-controlled, 2 × 2 factorial randomized trial enrolling 1708 patients aged 50 years or older who had experienced a myocardial infarction (MI) at least 6 weeks prior and had serum creatinine levels of 2.0 mg/dL or less. Participants were recruited at 134 US and Canadian sites. Enrollment began in September 2003 and follow-up took place until October 2011 (median, 55 months). Two hundred eighty-nine patients (17% of total; n=115 in the EDTA group and n=174 in the placebo group) withdrew consent during the trial. Patients were randomized to receive 40 infusions of a 500-mL chelation solution (3 g of disodium EDTA, 7 g of ascorbate, B vitamins, electrolytes, procaine, and heparin) (n=839) vs placebo (n=869) and an oral vitamin-mineral regimen vs an oral placebo. Infusions were administered weekly for 30 weeks, followed by 10 infusions 2 to 8 weeks apart. Fifteen percent discontinued infusions (n=38 [16%] in the chelation group and n=41 [15%] in the placebo group) because of adverse events. The prespecified primary end point was a composite of total mortality, recurrent MI, stroke, coronary revascularization, or hospitalization for angina. This report describes the intention-to-treat comparison of EDTA chelation vs placebo. To account for multiple interim analyses, the significance threshold required at the final analysis was P = .036. Qualifying previous MIs occurred a median of 4.6 years before enrollment. Median age was 65 years, 18% were female, 9% were nonwhite, and 31% were diabetic. The primary end point occurred in 222 (26%) of the chelation group and 261 (30%) of the placebo group (hazard ratio [HR], 0.82 [95% CI, 0.69-0.99]; P = .035). There was no effect on total mortality (chelation: 87 deaths [10%]; placebo, 93 deaths [11%]; HR, 0

Comparison of the octadentate bifunctional chelator DFO*-pPhe-NCS and the clinically used hexadentate bifunctional chelator DFO-pPhe-NCS for {sup 89}Zr-immuno-PET

Energy Technology Data Exchange (ETDEWEB)

Vugts, Danielle J.; Klaver, Chris; Sewing, Claudia; Poot, Alex J.; Adamzek, Kevin; Visser, Gerard W.M.; Dongen, Guus A.M.S. van [VU University Medical Center, Department of Radiology and Nuclear Medicine, Amsterdam (Netherlands); Huegli, Seraina; Mari, Cristina; Gasser, Gilles [University of Zurich, Department of Chemistry, Zurich (Switzerland); Valverde, Ibai E. [University of Basel Hospital, Division of Radiopharmaceutical Chemistry, Basel (Switzerland); Mindt, Thomas L. [Institute of Pharmaceutical Sciences, ETH Zurich, Zurich (Switzerland); General Hospital of Vienna, Ludwig Boltzmann Institute for Applied Diagnostics, Vienna (Austria)

2017-02-15

All clinical {sup 89}Zr-immuno-PET studies are currently performed with the chelator desferrioxamine (DFO). This chelator provides hexadentate coordination to zirconium, leaving two coordination sites available for coordination with, e.g., water molecules, which are relatively labile ligands. The unsaturated coordination of DFO to zirconium has been suggested to result in impaired stability of the complex in vivo and consequently in unwanted bone uptake of {sup 89}Zr. Aiming at clinical improvements, we report here on a bifunctional isothiocyanate variant of the octadentate chelator DFO* and the in vitro and in vivo comparison of its {sup 89}Zr-DFO*-mAb complex with {sup 89}Zr-DFO-mAb. The bifunctional chelator DFO*-pPhe-NCS was prepared from previously reported DFO* and p-phenylenediisothiocyanate. Subsequently, trastuzumab was conjugated with either DFO*-pPhe-NCS or commercial DFO-pPhe-NCS and radiolabeled with Zr-89 according to published procedures. In vitro stability experiments were carried out in saline, a histidine/sucrose buffer, and blood serum. The in vivo performance of the chelators was compared in N87 tumor-bearing mice by biodistribution studies and PET imaging. In 0.9 % NaCl {sup 89}Zr-DFO*-trastuzumab was more stable than {sup 89}Zr-DFO-trastuzumab; after 72 h incubation at 2-8 C 95 % and 58 % intact tracer were left, respectively, while in a histidine-sucrose buffer no difference was observed, both products were ≥ 92 % intact. In vivo uptake at 144 h post injection (p.i.) in tumors, blood, and most normal organs was similar for both conjugates, except for skin, liver, spleen, ileum, and bone. Tumor uptake was 32.59 ± 11.95 and 29.06 ± 8.66 % ID/g for {sup 89}Zr-DFO*-trastuzumab and {sup 89}Zr-DFO-trastuzumab, respectively. The bone uptake was significantly lower for {sup 89}Zr-DFO*-trastuzumab compared to {sup 89}Zr-DFO-trastuzumab. At 144 h p.i. for {sup 89}Zr-DFO*-trastuzumab and {sup 89}Zr-DFO-trastuzumab, the uptake in sternum was 0.92 �

Chiral DOTA chelators as an improved platform for biomedical imaging and therapy applications.

Science.gov (United States)

Dai, Lixiong; Jones, Chloe M; Chan, Wesley Ting Kwok; Pham, Tiffany A; Ling, Xiaoxi; Gale, Eric M; Rotile, Nicholas J; Tai, William Chi-Shing; Anderson, Carolyn J; Caravan, Peter; Law, Ga-Lai

2018-02-27

Despite established clinical utilisation, there is an increasing need for safer, more inert gadolinium-based contrast agents, and for chelators that react rapidly with radiometals. Here we report the syntheses of a series of chiral DOTA chelators and their corresponding metal complexes and reveal properties that transcend the parent DOTA compound. We incorporated symmetrical chiral substituents around the tetraaza ring, imparting enhanced rigidity to the DOTA cavity, enabling control over the range of stereoisomers of the lanthanide complexes. The Gd chiral DOTA complexes are shown to be orders of magnitude more inert to Gd release than [GdDOTA] - . These compounds also exhibit very-fast water exchange rates in an optimal range for high field imaging. Radiolabeling studies with (Cu-64/Lu-177) also demonstrate faster labelling properties. These chiral DOTA chelators are alternative general platforms for the development of stable, high relaxivity contrast agents, and for radiometal complexes used for imaging and/or therapy.

Structure of the first representative of Pfam family PF04016 (DUF364) reveals enolase and Rossmann-like folds that combine to form a unique active site with a possible role in heavy-metal chelation

International Nuclear Information System (INIS)

Miller, Mitchell D.; Aravind, L.; Bakolitsa, Constantina; Rife, Christopher L.; Carlton, Dennis; Abdubek, Polat; Astakhova, Tamara; Axelrod, Herbert L.; Chiu, Hsiu-Ju; Clayton, Thomas; Deller, Marc C.; Duan, Lian; Feuerhelm, Julie; Grant, Joanna C.; Han, Gye Won; Jaroszewski, Lukasz; Jin, Kevin K.; Klock, Heath E.; Knuth, Mark W.; Kozbial, Piotr; Krishna, S. Sri; Kumar, Abhinav; Marciano, David; McMullan, Daniel; Morse, Andrew T.; Nigoghossian, Edward; Okach, Linda; Reyes, Ron; Bedem, Henry van den; Weekes, Dana; Xu, Qingping; Hodgson, Keith O.; Wooley, John; Elsliger, Marc-André; Deacon, Ashley M.; Godzik, Adam; Lesley, Scott A.; Wilson, Ian A.

2010-01-01

The crystal structure of the first representative of DUF364 family reveals a combination of enolase N-terminal-like and C-terminal Rossmann-like folds. Analysis of the interdomain cleft combined with sequence and genome context conservation among homologs, suggests a unique catalytic site likely involved in the synthesis of a flavin or pterin derivative. The crystal structure of Dhaf4260 from Desulfitobacterium hafniense DCB-2 was determined by single-wavelength anomalous diffraction (SAD) to a resolution of 2.01 Å using the semi-automated high-throughput pipeline of the Joint Center for Structural Genomics (JCSG) as part of the NIGMS Protein Structure Initiative (PSI). This protein structure is the first representative of the PF04016 (DUF364) Pfam family and reveals a novel combination of two well known domains (an enolase N-terminal-like fold followed by a Rossmann-like domain). Structural and bioinformatic analyses reveal partial similarities to Rossmann-like methyltransferases, with residues from the enolase-like fold combining to form a unique active site that is likely to be involved in the condensation or hydrolysis of molecules implicated in the synthesis of flavins, pterins or other siderophores. The genome context of Dhaf4260 and homologs additionally supports a role in heavy-metal chelation

Synthesis of Two New Group 13 Benzoato-Chloro Complexes: A Structural Study of Gallium and Indium Chelating Carboxylates

Science.gov (United States)

Duraj, Stan A.; Hepp, Aloysius F.; Woloszynek, Robert; Protasiewicz, John D.; Dequeant, Michael; Ren, Tong

2010-01-01

Two new heteroleptic chelated-benzoato gallium (III) and indium (III) complexes have been prepared and structurally characterized. The molecular structures of [GaCl2(4-Mepy)2(O2CPh)]4-Mepy (1) and [InCl(4-Mepy)2(O2CPh)2]4-Mepy (2) have been determined by single-crystal x-ray diffraction. The gallium compound (1) is a distorted octahedron with cis-chloride ligands co-planar with the chelating benzoate and the 4-methylpyridines trans to each other. This is the first example of a Ga(III) structure with a chelating benzoate. The indium compound (2) is a distorted pentagonal bipyramid with two chelating benzoates, one 4-methylpyridine in the plane and a chloride trans to the other 4-methylpyridine. The indium bis-benzoate is an unusual example of a seven-coordinate structure with classical ligands. Both complexes, which due to the chelates, could also be described as pseudo-trigonal bipyramidal, include a three-bladed motif with three roughly parallel aromatic rings that along with a solvent of crystallization and electron-withdrawing chloride ligand(s) stabilize the solid-state structures.

Molecular-level characterization of crude oil compounds combining reversed-phase high-performance liquid chromatography with off-line high-resolution mass spectrometry

Science.gov (United States)

Sim, Arum; Cho, Yunju; Kim, Daae; Witt, Matthias; Birdwell, Justin E.; Kim, Byung Ju; Kim, Sunghwan

2014-01-01

A reversed-phase separation technique was developed in a previous study (Loegel et al., 2012) and successfully applied to the de-asphalted fraction of crude oil. However, to the best of our knowledge, the molecular-level characterization of oil fractions obtained by reversed-phase high-performance liquid chromatography (HPLC) coupled with high-resolution mass spectrometry (MS) has not yet been reported. A detailed characterization of the oil fractions prepared by reversed-phase HPLC was performed in this study. HPLC fractionation was carried out on conventional crude oil and an oil shale pyrolysate. The analyses of the fractions showed that the carbon number of alkyl chains and the double bond equivalent (DBE) value were the major factors determining elution order. The compounds with larger DBE (presumably more condensed aromatic structures) and smaller carbon number (presumably compounds with short side chains) were eluted earlier but those compounds with lower DBE values (presumably less aromatic structures) and higher carbon number (presumably compounds with longer alkyl chains) eluted later in the chromatograms. This separation behavior is in good agreement with that expected from the principles of reversed-phase separation. The data presented in this study show that reversed-phase chromatography is effective in separating crude oil compounds and can be combined with ultrahigh-resolution MS data to better understand natural oils and oil shale pyrolysates.

Assessment of the body burden of chelatable lead: a model and its application to lead workers

Energy Technology Data Exchange (ETDEWEB)

Araki, S.; Ushio, K.

1982-05-01

A hypothetical model was introduced to estimate the body burden of chelatable lead from the mobilisation yield of lead by calcium disodium ethylenediamine tetra-acetate. It was estimated that, on average, 14 and 19% of the body burden was mobilized into the urine during the 24 hours after an injection of 53.4 mumol and 107 mumol CaEDTA per kg bodyweight, respectively. The body burden of chelatable lead ranged from 4 mumol to 120 mumol in lead workers with blood lead concentrations of 0.3-2.9 mumol/kg. There were linear relationships between blood lead concentrations and body burden of chelatable lead on a log scale.

ParaCEST agents encapsulated in Reverse nano-Assembled Capsules (RACs): How slow molecular tumbling can quench CEST

Science.gov (United States)

Farashishiko, Annah; Slack, Jacqueline R.; Botta, Mauro; Woods, Mark

2018-04-01

Although paraCEST is a method with immense scope for generating image contrast in MRI, it suffers from the series the serious drawback of high detection limits. For a typical discrete paraCEST agent the detection limit is roughly an order of magnitude higher than that of a clinically used relaxation agent. One solution to this problem may be the incorporation of a large payload of paraCEST agents into a single macromolecular agent. Here we report a new synthetic method for accomplishing this goal: incorporating a large payload of the paraCEST agent DyDOTAM3+ into a Reverse Assembled nano-Capsule. An aggregate can be generated between this chelate and polyacrylic acid after the addition of ethylene diamine. Subsequent addition of polyallylamine hydrochloride followed by silica nanoparticles generated a robust encapsulating shell and afforded capsule with a mean hydrodynamic diameter of 650 ± 250 nm. Unfortunately this encapsulation did not have the effect of amplifying the CEST effect per agent, but quenched the CEST altogether. A significant proportion of the quenching effect of encapsulation could be attributed to the effect of slowing molecular tumbling, which is inevitable when the chelate is incorporated into a nano-scale material. This increases the transverse relaxation rate of chelate protons and a theoretical examination using Solomon Bloembergen Morgan theory and the Bloch equations shows that the increase in the transverse relaxation rate constant for the amide protons, in even modestly sized nano-materials, is sufficient to significantly quench CEST.

Rotating Reverse-Osmosis for Water Purification

Science.gov (United States)

Lueptow, RIchard M.

2004-01-01

A new design for a water-filtering device combines rotating filtration with reverse osmosis to create a rotating reverse- osmosis system. Rotating filtration has been used for separating plasma from whole blood, while reverse osmosis has been used in purification of water and in some chemical processes. Reverse- osmosis membranes are vulnerable to concentration polarization a type of fouling in which the chemicals meant not to pass through the reverse-osmosis membranes accumulate very near the surfaces of the membranes. The combination of rotating filtration and reverse osmosis is intended to prevent concentration polarization and thereby increase the desired flux of filtered water while decreasing the likelihood of passage of undesired chemical species through the filter. Devices based on this concept could be useful in a variety of commercial applications, including purification and desalination of drinking water, purification of pharmaceutical process water, treatment of household and industrial wastewater, and treatment of industrial process water. A rotating filter consists of a cylindrical porous microfilter rotating within a stationary concentric cylindrical outer shell (see figure). The aqueous suspension enters one end of the annulus between the inner and outer cylinders. Filtrate passes through the rotating cylindrical microfilter and is removed via a hollow shaft. The concentrated suspension is removed at the end of the annulus opposite the end where the suspension entered.

An optimized antibody-chelator conjugate for imaging of carcinoembryonic antigen with indium-111

International Nuclear Information System (INIS)

Sumerdon, G.A.; Rogers, P.E.; Lombardo, C.M.; Schnobrich, K.E.; Melvin, S.L.; Tribby, I.I.E.; Stroupe, S.D.; Johnson, D.K.; Hobart, E.D.

1990-01-01

A monoclonal antibody to carcinoembryonic antigen showing minimal cross-reactivity with blood cells and normal tissues was derivatized with benzylisothiocyanate derivatives of EDTA and DTPA. Seven chelators per immunoglobulin could be incorporated without loss of immunoreactivity. The resulting conjugates, labeled with indium-111, showed low liver uptake in animals. A cold kit, comprising the DTPA conjugate at a molarity of antibody bound chelator exceeding 1 x 10 -4 M, gave radiochemical yields of indium labeled antibody of ≥ 95% and was stable for 1 yr. (author)

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

International Nuclear Information System (INIS)

Li, Lingjun; Xu, Ming; Chen, Zhaoyong; Zhou, Xiang; Zhang, Qiaobao; Zhu, Huali; Wu, Chun; Zhang, Kaili

2015-01-01

The mechanisms and effects of three typical chelating agents, namely glucose, citric acid and sucrose on the sol-gel synthesis process, electrochemical degradation and structural evolution of 0.5Li 2 MnO 3 ·0.5LiNi 0.5 Co 0.2 Mn 0.3 O 2 (LLMO) materials are systematically compared for the first time. X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and high-resolution transmission electron microscopy analysis indicate that the sample synthesized from sucrose owns well structure, homogenous distribution, low Ni 3+ concentration and good surface structural stability during cycling, respectively. Electrochemical tests further prove that the LLMO material obtained from sucrose maintains 258.4 mAh g −1 with 94.8% capacity retention after 100 cycles at 0.2 C. The superior electrochemical performance can be ascribed to the exceptional complexing mechanism of sucrose, compared to those of the glucose and citric acid. Namely, one mole sucrose can be hydrolyzed into two different monosaccharides and further chelates three M (Li, Ni, Co and Mn) ions to form a more uniform ion-chelated matrix during sol-gel process. This discovery is an important step towards understanding the selection criterion of chelating agents for sol-gel method, that chelating agent with excellent complexing capability is beneficial to the distribution, structural stability and electrochemical properties of advanced lithium-rich layered materials

Chelation of di- and trivalent iron with some polyaminopolycarboxylic acids

International Nuclear Information System (INIS)

Hafez, M.B.; Sharabi, Nahid; Patti, Francois.

1979-02-01

The chelation of di- and trivalent iron with some polyaminopolycarboxylic acids was studied. The influence of pH on the formation of the complex was investigated, the molecular ratio and the stability constants were determined [fr

Mixed ligand chelate therapy for plutonium and cadmium poisoning

Energy Technology Data Exchange (ETDEWEB)

Schubert, J; Derr, S K [Hope Coll., Holland, MI (USA)

1978-09-28

Some experiments with mice are described in which complete removal of tissue deposits of /sup 239/Pu and prevention of mortality in animals given lethal doses of Cd were achieved using a mixed ligand chelate treatment (MLC). The mixed ligand consisted of diethylenetriaminepentaacetic acid and salicylic acid.

Effects of a diuretic and its combination with chelating agent on the removal of depleted uranium in rats

International Nuclear Information System (INIS)

Ikeda, Mizuyo; Fukuda, Satoshi; Nakamura, Mariko; Yoshida, Hiroki; Yan Xueming; Xie Yuyuan

2008-01-01

We examined the effects of a diuretic, isotonic saline, and chelating agent, catechol-3, 6-bis (methyleimiodiacetic acid) (CBMIDA), on the excretion and prevention of renal damage of depleted uranium (DU). Male Wistar rats (8 weeks old) divided into seven groups were preinjected intraperitoneally with 4 mg/kg DU and then the six groups were injected intraperitoneally with a diuretic, a diuretic plus isotonic saline, 480 mg/kg or 720 mg/kg CBMIDA alone, or 480 mg/kg or 720 mg/kg CBMIDA plus a diuretic and saline for three days, and the one group was as the control (no treatment). The rats were killed 6 days after DU injection. The results indicated that the diuretic alone and the diuretic with isotonic saline were not effective in removing uranium from the body and protecting the renal function, and also did not help to increase significantly the effects of CBMIDA. (author)

Encapsulation and retention of chelated-copper inside hydrophobic nanoparticles

DEFF Research Database (Denmark)

Hervella, Pablo; Ortiz, Elisa Parra; Needham, David

2016-01-01

) Chelate copper into the octaethyl porphyrin; (3) Encapsulate OEP-Cu in nanoparticles: the encapsulation efficiency of copper into liquid nanoparticles (LNP), solid nanoparticles (SNP) and phospholipid liposomes (PL) was evaluated by UV-Vis and atomic absorption spectroscopy; (4) Retain the encapsulated...... OEP-Cu in the liquid or solid cores of the nanoparticles in the presence of a lipid sink. RESULTS: (1) The size of the nanoparticles was found to be strongly dependent on the Reynolds number and the initial concentration of components for the fast injection technique. At high Reynolds number (2181......), a minimum value for the particle diameter of ∼30nm was measured. (2) Copper was chelated by OEP in a 1:1mol ratio with an association constant of 2.57×10(5)M(-1). (3) The diameter of the nanoparticles was not significantly affected by the presence of OEP or OEP-Cu. The percentage of encapsulation of copper...

Production of chelating agents by Pseudomonas aeruginosa grown in the presence of thorium and uranium

International Nuclear Information System (INIS)

Premuzic, E.T.; Lin, M.; Francis, A.J.; Schubert, J.

1986-01-01

Chelating agents produced by microorganisms enhance the dissolution of iron increasing the mobility and bioavailability of the metal. Since some similarities exist in the biological behavior of ferric, thorium and uranyl ions, microorganisms resistant to these metals and which grow in their presence may produce sequestering agents of Th and U, and other metals in a manner similar to the complexation of iron by siderophores. The ability of P. aeruginosa to elaborate sequestering agents in medium containing thorium or uranium salts was tested. Uranium has a stronger inhibitory effect on growth of the organism than thorium at similar concentrations. Analyses of the culture media have shown, that relative to the control, and under the experimental conditions used, the microorganisms have produced several new chelating agents for thorium and uranium. Extracts containing these chelating agents have been tested for their decorporation potential. In vitro mouse liver bioassay and in vivo mouse toxicity tests indicate that their efficiency is comparable to DTPA and DFOA and that they are virtually non-toxic to mice. The bacterially produced compounds resemble, but are not identical to the known iron chelating siderophores isolated from microorganisms. Some of their chemical properties are also discussed. (author)

Value of 1.0-M gadolinium chelates: review of preclinical and clinical data on gadobutrol

International Nuclear Information System (INIS)

Tombach, Bernd; Heindel, Walter

2002-01-01

Several preclinical and clinical studies with the first commercially available highly concentrated Gd-chelate gadobutrol (1 mol/l) are reviewed. Physicochemical, pharmacological, and pharmacokinetic properties, safety analysis, as well as experimental and clinical efficacy studies are highlighted in comparison with 0.5-M Gd-chelates. The 1-mol gadobutrol has been proven to be safe in an examined dose range from 0.04 up to 0.5 mmol/kg body weight (b.w.). Even in patients with chronic renal impairment, including hemodialysis, gadobutrol can safely be applied at doses up to 0.3 mmol/kg b.w. For contrast-enhanced MRI in the equilibrium phase, efficacy data analysis shows comparable results to other commercially available extracellular Gd-chelates with lower Gd-concentrations (0.5 M). Studies focused on the potential benefit of a tighter bolus, such as brain perfusion imaging using T2*-effects, document the superiority of a highly concentrated Gd contrast agent. For contrast-enhanced MRA, clinical studies are still ongoing; therefore, the ultimate potential of a more compact bolus, using 1-M Gd-chelates, for contrast-enhanced MRI, has still to be analyzed, especially for time-resolved magnetic resonance angiography. (orig.)

Effectiveness of DTPA Chelate on Cd Availability in Soils Treated with Sewage Sludge

Directory of Open Access Journals (Sweden)

Pegah Houshyar

2017-09-01

Full Text Available Application of sewage sludge as a fertilizer on farmlands is a common practice in most countries. Although the practice may play a positive role in plant performance, the organic amendments introduced may increase the soil heavy metals content. This study was conducted in Arak, Iran, to investigate the effectiveness of DTPA chelate on corn Cd availability in a sewage sludge treated soil. The treatments consisted of sewage sludge (0, 15, and 30 t ha-1 polluted with cadmium applied at 0, 5, 10, and 15 mg kg-1 as well as DTPA applied at 0 and 1.5 mmol kg-1 soil. Corn plants were then grown in the soil in each treatmnent and, on day 60, the physic-chemical characteristics and Cd quantities were measured ion both the corn plants and soil samples. Application of 1.5 m mol of DTPA chelate in soil contaminated with 5 mg Cd led to a significant increase in the soil available Cd content. It was also observed that application of DTPA chelate to soils containing 30 t ha-1 of sewage sludge polluted with 10 mg Cd increased root and shoot Cd concentrations by 17 and 25%, respectively. Results indicated the effectiveness of DTPA chelate in reducing Cd phytoremediation with increasing sewage sludge loading rate. This was evidenced by the lowest phytoremediation effectiveness observed for the treatment with the greatest sewage sludge loading (30 t ha-1 and the lowest cadmium pollution (5 mg Cd.

Localization of indium-111 in human malignant tumor xenografts and control by chelators

International Nuclear Information System (INIS)

Watanabe, Naoyuki; Oriuchi, Noboru; Endo, Keigo; Inoue, Tomio; Tanada, Shuji; Murata, Hajime; Kim, E. Edmund; Sasaki, Yasuhito

1999-01-01

The kinetics of soluble indium-111 ( 111 In) in human malignant tumor xenografts and cells was investigated in combination with chelators. Firstly, without chelator, the kinetics of 111 In-chloride was investigated in vitro and in vivo using four human malignant neuroblastoma SK-N-MC, pulmonary papillary adenocarcinoma NCI-H441, pulmonary squamous cell carcinoma PC 9, and colon adenocarcinoma LS 180 cells and xenografts. 111 In was incorporated into tumor cells in vitro to a maximum level during a 60-min incubation. A maximum level of radioactivity was demonstrated in vivo in four human malignant tumors xenografted into nude mice at 24 h postinjection of 111 In-chloride. Secondly, the effect of edetate calcium disodium (CaNa 2 EDTA) on radioactivity in 111 In-labeled tumors xenografts and cells was studied in vitro and in vivo. CaNa 2 EDTA significantly reduced 111 In-activity from the labeled tumor xenografts, whereas it had no affect on the radioactivity in the labeled cells. Thirdly, the effect of CaNa 2 EDTA on radioactivity in human malignant tumors xenografted into nude mice injected with 111 In-chloride was investigated. In one group of mice CaNa 2 EDTA administered intraperitoneally at 1, 22, 34, 46, 58, and 70 h after injection of 111 In-chloride (postadministration), the localization of 111 In at the tumors was significantly decreased at 72 h compared with the control in all four tumor types. In the other group of mice, CaNa 2 EDTA administered intraperitoneally at 12 and 1 h before injection of 111 In-chloride and 1, 22, 34, 46, 58, and 70 h postinjection (pre- and postadministration), the radioactivity of tumors was also significantly decreased at 72 h, and the reduction was greater than that with use of postadministration. In a comparative study, CaNa 3 DTPA had a more powerful effect than CaNa 2 EDTA. In conclusion, 111 In-activity in tumors consists of intracellular and extracellular components, and the extracellular 111 In may be cleared by

Novel combination of reverse engineering and vapid prototyping in medicine

CSIR Research Space (South Africa)

Schenker, R

1999-08-01

Full Text Available The technologies of reverse engineering and rapid prototyping are emerging as useful new tools in medicine. One application is of particular interest in orthopaedic, dental and reconstructive surgery. It involves the imaging, modelling...

Nature of the bifunctional chelating agent used for radioimmunotherapy with yttrium-88 monoclonal antibodies: critical factors in determining in vivo survival and organ toxicity

Energy Technology Data Exchange (ETDEWEB)

Kozak, R.W.; Raubitschek, A.; Mirzadeh, S.; Brechbiel, M.W.; Junghaus, R.; Gansow, O.A.; Waldmann, T.A. (Center for Biologics Evaluation and Research, FDA, Bethesda, MD (USA))

1989-05-15

One factor that is critical to the potential effectiveness of radioimmunotherapy is the design of radiometal-chelated antibodies that will be stable in vivo. Stability in vivo depends on the condition that both the chelate linkage and radiolabeling procedures not alter antibody specificity and biodistribution. In addition, synthesis and selection of the chelating agent is critical for each radiometal in order to prevent inappropriate release of the radiometal in vivo. In the present study, we compare the in vivo stability of seven radioimmunoconjugates that use different polyaminocarboxylate chelating agents to complex yttrium-88 to the mouse anti-human interleukin-2 receptor monoclonal antibody, anti-Tac. Chelate linkage and radiolabeling procedures did not alter the immunospecificity of anti-Tac. In order to assess whether yttrium was inappropriately released from the chelate-coupled antibody in vivo, iodine-131-labeled and yttrium-88 chelate-coupled antibodies were simultaneously administered to the same animals to correlate the decline in yttrium and radioiodinated antibody activity. The four stable yttrium-88 chelate-coupled antibodies studied displayed similar iodine-131 and yttrium-88 activity, indicating minimal elution of yttrium-88 from the complex. In contrast, the unstable yttrium-88 chelate-coupled antibodies had serum yttrium-88 activities that declined much more rapidly than their iodine-131 activities, suggesting loss of the radiolabel yttrium-88 from the chelate. Furthermore, high rates of yttrium-88 elution correlated with deposition in bone. Four chelating agents emerged as promising immunotherapeutic reagents: isothiocyanate benzyl DTPA and its derivatives 1B3M, MX, and 1M3B.

Effectiveness of chelation therapy with time after acute uranium intoxication

International Nuclear Information System (INIS)

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

1990-01-01

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

Chelating ligands: enhancers of quality and purity of biogas ...

African Journals Online (AJOL)

The quality of biogas depends largely on the percentage of methane and hydrogen sulphide gas present. High concentration of hydrogen sulphide results in low quality biogas. This work employed the use of chelating ligands in scrubbing hydrogen sulphide gas while improving the yield of methane gas. Experimental ...

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

Science.gov (United States)

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.

Antioxidant and mercury chelating activity of Psidium guajava var. pomifera L. leaves hydroalcoholic extract.

Science.gov (United States)

Pinho, Antonio Ivanildo; Oliveira, Cláudia Sirlene; Lovato, Fabricio Luís; Waczuk, Emily Pansera; Piccoli, Bruna Candia; Boligon, Aline Augusti; Leite, Nadghia Figueredo; Coutinho, Henrique Douglas Melo; Posser, Thais; Da Rocha, João Batista Teixeira; Franco, Jeferson Luis

2017-01-01

Mercury (Hg) is widely distributed in the environment and is known to produce several adverse effects in organisms. The aim of the present study was to examine the in vitro antioxidant activity and Hg chelating ability of the hydroalcoholic extract of Psidium guajava leaves (HEPG). In addition, the potential protective effects of HEPG against Hg(II) were evaluated using a yeast model (Saccharomyces cerevisiae). HEPG was found to exert significant antioxidant activity in 2,2-diphenyl-1-picrylhydrazyl scavenger and inhibition of lipid peroxidation induced by Fe(II) assays in a concentration-dependent manner. The extract also exhibited significant Hg(II) chelating activity. In yeast, Hg(II) induced a significant decrease in cell viability. In contrast, HEPG partially prevented the fall in cell viability induced by Hg(II). In conclusion, HEPG exhibited protective effects against Hg(II)-mediated toxicity, which may be related to both antioxidant and Hg(II)-chelating activities.

Studies on In-situ Chelation/Supercritical Fluid Extraction of Lanthanides and Actinides Using a Radiotracer Technique

International Nuclear Information System (INIS)

Lin, Yuehe; Wu, Hong; Smart, Neil G.; Wai, Chien M.

2001-01-01

Radioisotope tracer techniques were used to study the process of in-situ chelation/supercritical fluid extraction(SFE) of La3+ and Lu3+ from solid matrix using mixed ligand hexafluoroacetylacetone (HFA) and tributylphosphate (TBP) as chelating agents. A lab-built SFE extactor was used in this study and the extractor design was optimized based on the experimental results. Quantitative recovery of La and Lu was achieved when the extrator design was optimized. Extraction of uranium from real world samples was also investigated to demonstrate the capability of this chelation/SFE technology for environmental remediation applications. A novel on-line back extraction technique for the recovery of metal ions and regeneration of ligands is also reported.

Chronic Toxic Metal Exposure and Cardiovascular Disease: Mechanisms of Risk and Emerging Role of Chelation Therapy.

Science.gov (United States)

Aneni, Ehimen C; Escolar, Esteban; Lamas, Gervasio A

2016-12-01

Over the last few decades, there has been a growing body of epidemiologic evidence linking chronic toxic metal exposure to cardiovascular disease-related morbidity and mortality. The recent and unexpectedly positive findings from a randomized, double-blind, multicenter trial of metal chelation for the secondary prevention of atherosclerotic cardiovascular disease (Trial to Assess Chelation Therapy (TACT)) have focused the discussion on the role of chronic exposure to toxic metals in the development and propagation of cardiovascular disease and the role of toxic metal chelation therapy in the secondary prevention of cardiovascular disease. This review summarizes the most recent evidence linking chronic toxic metal exposure to cardiovascular disease and examines the findings of TACT.

ParaCEST Agents Encapsulated in Reverse Nano-Assembled Capsules (RACs: How Slow Molecular Tumbling Can Quench CEST Contrast

Directory of Open Access Journals (Sweden)

Annah Farashishiko

2018-04-01

Full Text Available Although paraCEST is a method with immense scope for generating image contrast in MRI, it suffers from the serious drawback of high detection limits. For a typical discrete paraCEST agent the detection limit is roughly an order of magnitude higher than that of a clinically used relaxation agent. One solution to this problem may be the incorporation of a large payload of paraCEST agents into a single macromolecular agent. Here we report a new synthetic method for accomplishing this goal: incorporating a large payload of the paraCEST agent DyDOTAM3+ into a Reverse Assembled nano-Capsule. An aggregate can be generated between this chelate and polyacrylic acid (PAA after the addition of ethylene diamine. Subsequent addition of polyallylamine hydrochloride (PAH followed by silica nanoparticles generated a robust encapsulating shell and afforded capsule with a mean hydrodynamic diameter of 650 ± 250 nm. Unfortunately this encapsulation did not have the effect of amplifying the CEST effect per agent, but quenched the CEST altogether. The quenching effect of encapsulation could be attributed to the effect of slowing molecular tumbling, which is inevitable when the chelate is incorporated into a nano-scale material. This increases the transverse relaxation rate of chelate protons and a theoretical examination using Solomon Bloembergen Morgan theory and the Bloch equations shows that the increase in the transverse relaxation rate constant for the amide protons, in even modestly sized nano-materials, is sufficient to significantly quench CEST.

ParaCEST Agents Encapsulated in Reverse Nano-Assembled Capsules (RACs): How Slow Molecular Tumbling Can Quench CEST Contrast.

Science.gov (United States)

Farashishiko, Annah; Slack, Jacqueline R; Botta, Mauro; Woods, Mark

2018-01-01

Although paraCEST is a method with immense scope for generating image contrast in MRI, it suffers from the serious drawback of high detection limits. For a typical discrete paraCEST agent the detection limit is roughly an order of magnitude higher than that of a clinically used relaxation agent. One solution to this problem may be the incorporation of a large payload of paraCEST agents into a single macromolecular agent. Here we report a new synthetic method for accomplishing this goal: incorporating a large payload of the paraCEST agent DyDOTAM 3+ into a Reverse Assembled nano-Capsule. An aggregate can be generated between this chelate and polyacrylic acid (PAA) after the addition of ethylene diamine. Subsequent addition of polyallylamine hydrochloride (PAH) followed by silica nanoparticles generated a robust encapsulating shell and afforded capsule with a mean hydrodynamic diameter of 650 ± 250 nm. Unfortunately this encapsulation did not have the effect of amplifying the CEST effect per agent, but quenched the CEST altogether. The quenching effect of encapsulation could be attributed to the effect of slowing molecular tumbling, which is inevitable when the chelate is incorporated into a nano-scale material. This increases the transverse relaxation rate of chelate protons and a theoretical examination using Solomon Bloembergen Morgan theory and the Bloch equations shows that the increase in the transverse relaxation rate constant for the amide protons, in even modestly sized nano-materials, is sufficient to significantly quench CEST.

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

International Nuclear Information System (INIS)

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

2007-01-01

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

Iron chelating activity, phenol and flavonoid content of some ...

African Journals Online (AJOL)

STORAGESEVER

2008-09-17

Sep 17, 2008 ... require regular blood transfusions in order to improve both quality of ... fused red blood cells and the excess iron is deposited as ... potentiation of reactive oxygen species (ROS) and .... The percentage inhibition of ferrozine–Fe2+ complex formation was ... estimation of the chelating activity of the coexisting.

Effect of different chelated zinc sources on the growth and yield of maize (Zea mays L.

Directory of Open Access Journals (Sweden)

M. Tahir

2009-05-01

Full Text Available A field study was conducted at Agronomic Research Area, University of Agriculture, Faisalabad during spring, 2007 to evaluate the effect of different chelated zinc sources on growth and yield of maize (Zea mays L.. Crop was sown on well prepared soil in 1st week of March, 2007. The experiment was laid out according to randomized complete block design. The treatments comprised of different chelated zinc sources: ZnSO4-DTPA, ZnSO4-Fulvate, ZnSO4-Lignosulphonate, ZnSO4-EDTA and ZnSO4-H2O along with control (no zinc, repeated three times. Results showed that number of cobs plant-1, grain rows cob-1 and oil contents did not differ significantly. However, differences among treatments for plant height at harvest (cm, leaf area plant-1 (cm2, stem diameter (cm, cob length (cm, cob diameter (cm, 100-grains weight (g, number of grains cob-1, grains weight cob-1(g, biological yield (tons ha-1, grain yield (tons ha-1 and protein contents (% were significantly higher. Moreover, results also revealed that ZnSO4-DPTA was found the most effective Zn chelated source among all the treatments. Rest of the chelating agents were not too impressive as they showed varied response for different variables. The result of this experiment suggest further experimentation to explore behaviour of Zn-DTPA with other macro and micro nutrients and to calculate cost benefit ratio for use ofZn chelated compounds.

Labeling of antibodies with a 67Ga-phenolic aminocarboxylic acid chelate. Pt. 1

International Nuclear Information System (INIS)

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 tighly complexes 67 Ga, was synthetized. The 67 Ga-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 67 Ga. In vitro stability was evaluated in human serum at 37 0 C and showed a half-life of about 120 h for the release of 67 Ga from the labeled Ab during the initial phase of incubation. This in vitro halflife is similar to that measured for 111 In-DTPA labeled Abs. Because of the high stability of the 67 Ga-P-EDDHA chelate, the in vivo formation of radioactive lebeled transferrin by transchelation, as described for 111 In-DTPA labeled Abs, should, however, be reduced by this labeling technique. (orig.)

The performance of 2-nitroso-1-naphthol chelating pigment in paint ...

African Journals Online (AJOL)

The performance of 2-nitroso-1-naphthol chelating pigment in paint formulation with gum Arabic and polyvinyl acetate as binders, Paper I: UV- visible spectroscopy, viscosity and breaking stress of the paints.

Parallelization of Reversible Ripple-carry Adders

DEFF Research Database (Denmark)

Thomsen, Michael Kirkedal; Axelsen, Holger Bock

2009-01-01

The design of fast arithmetic logic circuits is an important research topic for reversible and quantum computing. A special challenge in this setting is the computation of standard arithmetical functions without the generation of \\emph{garbage}. Here, we present a novel parallelization scheme...... wherein $m$ parallel $k$-bit reversible ripple-carry adders are combined to form a reversible $mk$-bit \\emph{ripple-block carry adder} with logic depth $\\mathcal{O}(m+k)$ for a \\emph{minimal} logic depth $\\mathcal{O}(\\sqrt{mk})$, thus improving on the $mk$-bit ripple-carry adder logic depth $\\mathcal...

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

International Nuclear Information System (INIS)

Fontes, Andre; Prata, M. Isabel M.; Geraldes, Carlos F.G.C.; Andre, Joao P.

2011-01-01

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.

The effectiveness of various chelates used alone or in combination with sodium hypochlorite in the removal of calcium hydroxide from root canals

Directory of Open Access Journals (Sweden)

Emel Uzunoglu

2015-01-01

Full Text Available Aim: To evaluate the effectiveness of various chelates used alone or in combination with sodium hypochlorite (NaOCl in the removal of calcium hydroxide (Ca(OH2 from root canals. Materials and Methods: The root canals of 72 mandibular incisors were prepared up to the ProTaper F2 file. Among these, six randomly selected teeth were used as negative and positive controls, while the root canals of the remaining 66 were filled with Ca(OH2 paste for 1 week. Then, the experimental group specimens were divided into six groups (n = 11. The access cavities were reopened and the Ca(OH2 paste in each group was removed using the following solutions: 2.5 mL ethylenediaminetetraacetic acid (EDTA; Group 1, 2.5 mL peracetic acid (PAA; Group 2, 2.5 mL QMix (Group 3, 2.5 mL NaOCl/2.5 mL EDTA (Group 4, 2.5 mL NaOCl/2.5 mL PAA (Group 5, and 2.5 mL NaOCl/2.5 mL QMix (Group 6. Digital photographs of longitudinally split specimens were imported into image analyzer software, and the amount of residual Ca (OH 2 was recorded as a percentage of the overall canal surface area. The results were analyzed using Kruskal–Wallis and Conover–Dunn tests. Results: The canal walls in the positive control group were completely covered with Ca(OH 2 compared with those in the negative control group. The lowest Ca(OH2 removal efficiency was observed for Group 4 (P < 0.001, while Group 6 showed favorable results (P < 0.05. Conclusions: QMix combined with NaOCl can remove Ca(OH2 from root canals as effectively as 17% EDTA and 1% PAA. The type and sequence of irrigants are more important than the total irrigant volume for effective Ca(OH 2 removal.

Reverse-symmetry waveguides: Theory and fabrication

DEFF Research Database (Denmark)

Horvath, R.; Lindvold, Lars René; Larsen, N.B.

2002-01-01

We present an extensive theoretical analysis of reverse-symmetry waveguides with special focus on their potential application as sensor components in aqueous media and demonstrate a novel method for fabrication of such waveguides. The principle of reverse symmetry is based on making the refractive...... index of the waveguide substrate less than the refractive index of the medium covering the waveguiding film (n(water) = 1.33). This is opposed to the conventional waveguide geometry, where the substrate is usually glass or polymers with refractive indices of approximate to1.5. The reverse configuration...... are combined with air-grooved polymer supports to form freestanding single-material polymer waveguides of reverse symmetry capable of guiding light....

Online combination of reversed-phase/reversed-phase and porous graphitic carbon liquid chromatography for multicomponent separation of proteomics and glycoproteomics samples.

Science.gov (United States)

Lam, Maggie P Y; Lau, Edward; Siu, S O; Ng, Dominic C M; Kong, Ricky P W; Chiu, Philip C N; Yeung, William S B; Lo, Clive; Chu, Ivan K

2011-11-01

In this paper, we describe an online combination of reversed-phase/reversed-phase (RP-RP) and porous graphitic carbon (PGC) liquid chromatography (LC) for multicomponent analysis of proteomics and glycoproteomics samples. The online RP-RP portion of this system provides comprehensive 2-D peptide separation based on sequence hydrophobicity at pH 2 and 10. Hydrophilic components (e.g. glycans, glycopeptides) that are not retained by RP are automatically diverted downstream to a PGC column for further trapping and separation. Furthermore, the RP-RP/PGC system can provide simultaneous extension of the hydropathy range and peak capacity for analysis. Using an 11-protein mixture, we found that the system could efficiently separate native peptides and released N-glycans from a single sample. We evaluated the applicability of the system to the analysis of complex biological samples using 25 μg of the lysate of a human choriocarcinoma cell line (BeWo), confidently identifying a total of 1449 proteins from a single experiment and up to 1909 distinct proteins from technical triplicates. The PGC fraction increased the sequence coverage through the inclusion of additional hydrophilic sequences that accounted for up to 6.9% of the total identified peptides from the BeWo lysate, with apparent preference for the detection of hydrophilic motifs and proteins. In addition, RP-RP/PGC is applicable to the analysis of complex glycomics samples, as demonstrated by our analysis of a concanavalin A-extracted glycoproteome from human serum; in total, 134 potentially N-glycosylated serum proteins, 151 possible N-glycosylation sites, and more than 40 possible N-glycan structures recognized by concanavalin A were simultaneously detected. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

Energy Technology Data Exchange (ETDEWEB)

Boiteau, Rene M.; Shaw, Jared B.; Pasa Tolic, Ljiljana; Koppenaal, David W.; Jansson, Janet K.

2018-05-01

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. Even small structural differences

A time reversal damage imaging method for structure health monitoring using Lamb waves

International Nuclear Information System (INIS)

Zhang Hai-Yan; Cao Ya-Ping; Sun Xiu-Li; Chen Xian-Hua; Yu Jian-Bo

2010-01-01

This paper investigates the Lamb wave imaging method combining time reversal for health monitoring of a metallic plate structure. The temporal focusing effect of the time reversal Lamb waves is investigated theoretically. It demonstrates that the focusing effect is related to the frequency dependency of the time reversal operation. Numerical simulations are conducted to study the time reversal behaviour of Lamb wave modes under broadband and narrowband excitations. The results show that the reconstructed time reversed wave exhibits close similarity to the reversed narrowband tone burst signal validating the theoretical model. To enhance the similarity, the cycle number of the excited signal should be increased. Experiments combining finite element model are then conducted to study the imaging method in the presence of damage like hole in the plate structure. In this work, the time reversal technique is used for the recompression of Lamb wave signals. Damage imaging results with time reversal using broadband and narrowband excitations are compared to those without time reversal. It suggests that the narrowband excitation combined time reversal can locate and determine the size of structural damage more precisely, but the cycle number of the excited signal should be chosen reasonably

Chelate forms of biometalls. Theoretical aspects of obtaining and characteristics

Directory of Open Access Journals (Sweden)

A. Kapustyan

2017-04-01

Full Text Available The problem of microelements bioavailability is highlighted and the correct ways of its solution are substantiated as a result of generalization of theoretical aspects of obtaining of the biometals chelate forms. The characteristics of the main biogenic elements, their physiological significance, electrochemical properties are presented. The main examples of the participation of biometals in various biological processes are given. The properties and the structure peculiarities of biometals coordination complexes are considered in detail. It is shown that in obtaining of biometals chelate forms, there is the mutual selectivity and the affinity of biometals and ligands. The main factors of obtaining a hard metal complex are given. Potential bioligands for obtaining bioavailable forms of microelements are detailed. Among them there are amino acids, peptides, proteins, nucleic acids, carbohydrates. The possible character of complexation depending on the nature of the bioligand is indicated. Practical examples of preparation of biometals mixed ligand complexes are given. The expediency of using metabolic products and processing of lactic acid bacteria as promising components of mixed ligand chelate complexes is substantiated. These substances contain in their composition a mass of potential donor atoms that are capable to form covalent and coordination bonds with biomethalles, and also possess high biological and immunotropic activities. The use of this system in the biocoordination compounds of the "metals of life" can provide a synergistic effect of the components, significantly to expand the range of their physiological activity and to increase the degree of assimilation by the body.

STUDY ON THE KINETICS OF POLYMERIZATION OF MMA BY COPPER（Ⅱ） CHELATING RESINS

Institute of Scientific and Technical Information of China (English)

WangHongzuo; JiangYuanzhang; 等

1993-01-01

The polymerization of MMA initiated by copper(Ⅱ） chelating resins/CCl4 system was studied.From the kinetic data,the kinetic equation of polymerization can be expressed as Rp=Ke-56400/RT[MMA]1.57[CCl4]m[RESIN-Cu]0.18 where m:3-4.5,when[CCl4] 0.1-6.93M.The free radical polymerization mechanism is proposed.The primary radicals are formed by the process of complexation-chlorine transformation among the copper(Ⅱ) chelating resin,CCl4 and methacrylate.

Design and Methodology of the Trial to Assess Chelation Therapy (TACT)

Science.gov (United States)

Lamas, Gervasio A.; Goertz, Christine; Boineau, Robin; Mark, Daniel B.; Rozema, Theodore; Nahin, Richard L.; Drisko, Jeanne A.; Lee, Kerry L.

2011-01-01

The Trial to Assess Chelation Therapy (TACT) is an NIH-sponsored, randomized, double blind, placebo-controlled, 2×2 factorial clinical trial testing the benefits and risks of 40 infusions of a multi-component Na2EDTA-chelation solution compared with placebo, and of an oral, high-dose multivitamin and mineral supplement. TACT has randomized and will follow 1708 patients for an average of approximately 4 years. The primary endpoint is a composite of all cause mortality, myocardial infarction, stroke, coronary revascularization, and hospitalization for angina. A 900 patient substudy will examine quality of life outcomes. The trial is designed to have >85% power to detect a 25% relative reduction in the primary endpoint for each treatment factor. Enrollment began in September 2003 and completed in October 2010. PMID:22172430

Study on Selective Removal of Impurity Iron from Leached Copper-Bearing Solution Using a Chelating Resin

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Yubiao Li

2016-10-01

Full Text Available In order to selectively remove iron from copper laden solution after leaching but prior to electrowinning, equilibrium, kinetic, and thermodynamic studies have been conducted on an a chelating resin of Rexp-501 at pH 1.0 and at various temperatures. Both Langmuir and Freundlich models were investigated, with the Langmuir model proving to be more suitable for fitting iron removal performance, with little influence from copper concentration. Compared with the pseudo first order kinetic model, the pseudo second order kinetic model fitted the dynamic adsorption process better, indicating a chemisorption mechanism. Fourier transform infrared spectroscopy (FT-IR results indicated that C=O from carbonyl group played a key role in combining with iron and can be regenerated and reused. However, the C=O of the acylamino group combining with iron was not able to be released after oxalic acid was applied.

Selective separation of indium by iminodiacetic acid chelating resin

International Nuclear Information System (INIS)

Fortes, M.C.B.; Benedetto, J.S.; Martins, A.H.

2007-01-01

- Indium can be recovered by treating residues, flue dusts, slags, and metallic intermediates in zinc smelting. This paper investigates the adsorption characteristics of indium and iron on an iminodiacetic acid chelating resin, Amberlite R IRC748 (Rohm and Haas Co.-USA). High concentrations of iron are always present in the aqueous feed solution of indium recovery. In addition, the chemical behaviour of iron in adsorptive systems is similar to that of indium. The metal concentrations in the aqueous solution were based on typical indium sulfate leach liquor obtained from zinc hydrometallurgical processing in a Brazilian plant. The ionic adsorption experiments were carried out by the continuous column method. Amberlite R IRC748 resin had a high affinity for indium under acidic conditions. Indium ions adsorbed onto the polymeric resin were eluted with a 0.5 mol/dm 3 sulphuric acid solution passed through the resin bed in the column. 99.5% pure indium sulfate aqueous solution was obtained using the iminodiacetic acid chelating resin Amberlite R IRC748. (author)

Effect of soil washing with only chelators or combining with ferric chloride on soil heavy metal removal and phytoavailability: Field experiments.

Science.gov (United States)

Guo, Xiaofang; Wei, Zebin; Wu, Qitang; Li, Chunping; Qian, Tianwei; Zheng, Wei

2016-03-01

In a field experiment on multi-metal contaminated soil, we investigated the efficiency of Cd, Pb, Zn, and Cu removal by only mixture of chelators (MC) or combining with FeCl3. After washing treatment, a co-cropping system was performed for heavy metals to be extracted by Sedum alfredii and to produce safe food from Zea mays. We analyzed the concentration of heavy metals in groundwater to evaluate the leashing risk of soil washing with FeCl3 and MC. Results showed that addition of FeCl3 was favorable to the removal of heavy metals in the topsoil. Metal leaching occurred mainly in rain season during the first co-cropping. The removal rates of Cd, Zn, Pb, and Cu in topsoil were 28%, 53%, 41%, and 21% with washing by FeCl3+MC after first harvest. The application of FeCl3 reduced the yield of S. alfredii and increased the metals concentration of Z. mays in first harvest. However, after amending soil, the metals concentration of Z. mays in FeCl3+MC treatment were similar to that only washing by MC. The grains and shoots of Z. mays were safe for use in feed production. Soil washing did not worsen groundwater contamination during the study period. But the concentration of Cd in groundwater was higher than the limit value of Standard concentrations for Groundwater IV. This study suggests that soil washing using FeCl3 and MC for the remediation of multi-metal contaminated soil is potential feasibility. However, the subsequent measure to improve the washed soil environment for planting crop is considered. Copyright © 2016. Published by Elsevier Ltd.

Photophysical investigation of energy transfer luminescence of lanthanide chelates with aromatic polyaminocarboxylate ligands in aqueous solutions

International Nuclear Information System (INIS)

Hoshino, Hitoshi; Saitoh, Takashi; Yotsuyanagi, Takao

1995-01-01

Some photophysical data including emission lifetimes (τ), total emission quantum yields (Φ), and ligand phosphorescence data are reported for the energy-transfer luminescence of the Eu(III) chelate of Quin 2 and the Tb(III) chelate of BAPTA: Quin 2 means 2-[(2-amino-5-methylphenoxy)methyl]-6-methoxy-8-aminoquinoline-N,N,N',N'-tetraacetic acid; BAPTA means 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid. The energy diagrams for the ligand T 1 and the metal-center f-f levels are proposed. The τ values of Tb(III)-BAPTA chelates are 1.73 ms in H 2 O and 3.44 ms in D 2 O. The Eu(III)-Quin 2 chelate system shows a bi-exponential decay of emission; τ=0.048 and 0.20 ms in H 2 O and 0.066 and 1.44 ms in D 2 O. The Quin 2 chelate is kinetically inert, so that the interchange of these two conformer structures are very slow at room temperature. The number of water molecules in the primary coordination sphere is calculated from the lifetime data to be 1.9-2.4 for Eu-Quin 2 and 0.5 for Tb-BAPTA. The Φ values in aqueous solutions are rather small in these systems; 0.009 for Tb-BAPTA and 0.0023 for Eu-Quin 2, but these are enough counterbalanced by the large molar absorptivities giving the great sensitization factors for the ions; the sensitization factors against each aqua ion are 1380 for Eu-Quin 2 and 1600 for Tb-BAPTA. (author)

Zn2+ chelation by serum albumin improves hexameric Zn2+-insulin dissociation into monomers after exocytosis.

Directory of Open Access Journals (Sweden)

José A G Pertusa

Full Text Available β-cells release hexameric Zn2+-insulin into the extracellular space, but monomeric Zn2+-free insulin appears to be the only biologically active form. The mechanisms implicated in dissociation of the hexamer remain unclear, but they seem to be Zn2+ concentration-dependent. In this study, we investigate the influence of albumin binding to Zn2+ on Zn2+-insulin dissociation into Zn2+-free insulin and its physiological, methodological and therapeutic relevance. Glucose and K+-induced insulin release were analyzed in isolated mouse islets by static incubation and perifusion experiments in the presence and absence of albumin and Zn2+ chelators. Insulin tolerance tests were performed in rats using different insulin solutions with and without Zn2+ and/or albumin. Albumin-free buffer does not alter quantification by RIA of Zn2+-free insulin but strongly affects RIA measurements of Zn2+-insulin. In contrast, accurate determination of Zn2+-insulin was obtained only when bovine serum albumin or Zn2+ chelators were present in the assay buffer solution. Albumin and Zn2+ chelators do not modify insulin release but do affect insulin determination. Preincubation with albumin or Zn2+ chelators promotes the conversion of "slow" Zn2+-insulin into "fast" insulin. Consequently, insulin diffusion from large islets is ameliorated in the presence of Zn2+ chelators. These observations support the notion that the Zn2+-binding properties of albumin improve the dissociation of Zn2+-insulin into subunits after exocytosis, which may be useful in insulin determination, insulin pharmacokinetic assays and islet transplantation.

To chelate or not to chelate in MDS: That is the question!

Science.gov (United States)

Zeidan, Amer M; Griffiths, Elizabeth A

2018-03-08

Myelodysplastic syndromes (MDS) are a heterogeneous group of hemopathies that exhibit physical manifestations with clinical consequences of bone marrow failure and inherent risk of progression to acute myeloid leukemia. Iron overload (IO) is common in MDS due to chronic transfusion support and disease-related alterations in iron metabolism. IO has been conclusively associated with inferior outcomes among MDS patients. Despite lack of randomized trials showing a survival impact of iron chelation therapy (ICT), ICT is recommended by experts and guidelines for select MDS patients with IO and is often used. The availability of effective oral ICT agents has reignited the controversy regarding ICT use in patients with MDS and IO. Here we summarize the studies evaluating the value of ICT in MDS and suggest a practical approach for use of these therapies. We also highlight controversies regarding use of ICT in MDS and discuss some ongoing efforts to answer these questions. Copyright © 2018 Elsevier Ltd. All rights reserved.

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

Science.gov (United States)

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.

A reversion of an IL2RG mutation in combined immunodeficiency providing competitive advantage to the majority of CD8+ T cells.

Science.gov (United States)

Kuijpers, Taco W; van Leeuwen, Ester M M; Barendregt, Barbara H; Klarenbeek, Paul; aan de Kerk, Daan J; Baars, Paul A; Jansen, Machiel H; de Vries, Niek; van Lier, René A W; van der Burg, Mirjam

2013-07-01

Mutations in the common gamma chain (γc, CD132, encoded by the IL2RG gene) can lead to B(+)T(-)NK(-) X-linked severe combined immunodeficiency, as a consequence of unresponsiveness to γc-cytokines such as interleukins-2, -7 and -15. Hypomorphic mutations in CD132 may cause combined immunodeficiencies with a variety of clinical presentations. We analyzed peripheral blood mononuclear cells of a 6-year-old boy with normal lymphocyte counts, who suffered from recurrent pneumonia and disseminated mollusca contagiosa. Since proliferative responses of T cells and NK cells to γc -cytokines were severely impaired, we performed IL2RG gene analysis, showing a heterozygous mutation in the presence of a single X-chromosome. Interestingly, an IL2RG reversion to normal predominated in both naïve and antigen-primed CD8(+) T cells and increased over time. Only the revertant CD8(+) T cells showed normal expression of CD132 and the various CD8(+) T cell populations had a different T-cell receptor repertoire. Finally, a fraction of γδ(+) T cells and differentiated CD4(+)CD27(-) effector-memory T cells carried the reversion, whereas NK or B cells were repeatedly negative. In conclusion, in a patient with a novel IL2RG mutation, gene-reverted CD8(+) T cells accumulated over time. Our data indicate that selective outgrowth of particular T-cell subsets may occur following reversion at the level of committed T progenitor cells.

Effects of nutrient trace metal speciation on algal growth in the presence of the chelator [S,S]-EDDS

NARCIS (Netherlands)

Schowanek, D.; McAvoy, D.; Versteeg, D.; Hanstveit, A.

1996-01-01

This study tests the hypothesis that the apparent toxicity of strong chelators in standard algal growth inhibition tests (e.g. method OECD 201, EC C.3., ISO 8692) is related to essential trace metal bioavailability. This hypothesis was investigated for the chelator [S,S]-ethylene diamine disuccinate

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

Energy Technology Data Exchange (ETDEWEB)

Fontes, Andre [Centro de Quimica, Campus de Gualtar, Universidade do Minho, 4710-057, Braga (Portugal); Prata, M. Isabel M. [IBILI, Faculdade de Medicina, Universidade de Coimbra, 3548, Coimbra (Portugal); Geraldes, Carlos F.G.C. [Departamento de Ciencias da Vida, Faculdade de Ciencias e Tecnologia, Universidade de Coimbra, 3001-401, Coimbra (Portugal); Centro de Neurociencias e Biologia Celular, Universidade de Coimbra, 3001-401, Coimbra (Portugal); Andre, Joao P., E-mail: jandre@quimica.uminho.p [Centro de Quimica, Campus de Gualtar, Universidade do Minho, 4710-057, Braga (Portugal)

2011-04-15

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 {alpha}-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 {sup 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.

Decontamination of process equipment using recyclable chelating solvent

Energy Technology Data Exchange (ETDEWEB)

Jevec, J.; Lenore, C.; Ulbricht, S. [Babcock & Wilcox, Co., R& DD, Alliance, OH (United States)

1995-10-01

The Department of Energy (DOE) is now faced with the task of meeting decontamination and decommissioning obligations at numerous facilities by the year 2019. Due to the tremendous volume of material involved, innovative decontamination technologies are being sought that can reduce the volumes of contaminated waste materials and secondary wastes requiring disposal. This report describes the results of the performance testing of chelates and solvents for the dissolution of uranium.

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

DEFF Research Database (Denmark)

Brewer, Casey; Otto-Duessel, Maya; Lykkesfeldt, Jens

2012-01-01

Iron chelation is essential to patients on chronic blood transfusions to prevent toxicity from iron overload and remove excess iron. Deferasirox (DFX) is the most commonly used iron chelator in the United States; however, some patients are relatively refractory to DFX therapy. We postulated...... that vitamin C supplementation would improve the availability of transfusional iron to DFX treatment by promoting iron's redox cycling, increasing its soluble ferrous form and promoting its release from reticuloendothelial cells. Osteogenic dystrophy rats (n = 54) were given iron dextran injections for 10...... 12 weeks of sham chelation. Most importantly, ascorbate supplementation at 2250 ppm improved DFX efficiency, allowing DFX to remove 21% more hepatic iron than ascorbate supplementation with 900 ppm or 150 ppm (p vitamin C status modulates the release of iron from...

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

Energy Technology Data Exchange (ETDEWEB)

Gao, Xiaolong [Department of Radiology, Tongji Hospital, Tongji University School of Medicine, Shanghai 200065 (China); Wang, Gangmin [Department of Urology, Huashan Hospital, Fudan University, Shanghai 200040 (China); Shi, Ting [The Institute for Translational Nanomedicine, Shanghai East Hospital, Institute for Biomedical Engineering and Nanoscience, Tongji University School of Medicine, Shanghai 200092 (China); Shao, Zhihong [Department of Radiology, Tongji Hospital, Tongji University School of Medicine, Shanghai 200065 (China); Zhao, Peng; Shi, Donglu [The Institute for Translational Nanomedicine, Shanghai East Hospital, Institute for Biomedical Engineering and Nanoscience, Tongji University School of Medicine, Shanghai 200092 (China); Ren, Jie [Institute of Nano and Biopolymeric Materials, School of Materials Science and Engineering, Tongji University, 4800 Caoan Road, Shanghai 201804 (China); Lin, Chao, E-mail: chaolin@tongji.edu.cn [The Institute for Translational Nanomedicine, Shanghai East Hospital, Institute for Biomedical Engineering and Nanoscience, Tongji University School of Medicine, Shanghai 200092 (China); Wang, Peijun, E-mail: tjpjwang@sina.com [Department of Radiology, Tongji Hospital, Tongji University School of Medicine, Shanghai 200065 (China)

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 T{sub 1}-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 25 kDa 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 T{sub 1}-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. - Highlights: • Novel cationic gadolinium-chelated poly(urethane amide)s (GdCPUAs) are prepared. • GdCPUAs can induce a high transfection efficacy in different cancer cells. • GdCPUAs reveal good cyto-compatibility against cancer cells. • GdCPUAs may be applied as T{sub 1}-contrast agents for magnetic resonance imaging. • GdCPUAs hold high potential for cancer theranostics.

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

International Nuclear Information System (INIS)

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

2016-01-01

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 T 1 -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 25 kDa 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 T 1 -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. - Highlights: • Novel cationic gadolinium-chelated poly(urethane amide)s (GdCPUAs) are prepared. • GdCPUAs can induce a high transfection efficacy in different cancer cells. • GdCPUAs reveal good cyto-compatibility against cancer cells. • GdCPUAs may be applied as T 1 -contrast agents for magnetic resonance imaging. • GdCPUAs hold high potential for cancer theranostics.

Bone marrow and chelatable iron in patients with protein energy ...

African Journals Online (AJOL)

Objectives: To examine the iron status of malnourished children by comparing bone marrow iron deposits in children with protein energy malnutrition with those in well-nourished controls, and measuring chelatable urinary iron excretion in children with kwashiorkor. Design: Bone marrow iron was assessed histologicaHy in ...

Treatment of some radioactive wastes by using new chelating membranes

International Nuclear Information System (INIS)

Hegazy, S.A.; El-Adham, K.; Abdel Geleel, M.; Soliman, S.A.

2000-01-01

The preparation of chelating membranes containing nitrile and carboxylic acid as functional groups was investigated. The modification of such membranes by chemical treatments to produce significant changes in their properties was studied. This modification results in a higher rate of exchange and higher capacity. The applicability of such modified membranes in the removal of Co-60 and Cs-137 from their wastes were tested. The dependence of these radioactive nuclides uptake on the time and degree of grafting for H CI-, NH 2 OH-and KOH-treated membranes was investigated. It was found that the adsorption rate and capacity were higher for KOH-treated membrane than those for the NH 2 OH and H CI treated ones. The prepared grafted membranes have a good affinity towards the adsorption or chelation with Co-60 and Cs-137. This result may make such prepared materials acceptable for practicable use in some radioactive waste treatments and recovery

Phosphinic acid functionalized polyazacycloalkane chelators for radiodiagnostics and radiotherapeutics: unique characteristics and applications.

Science.gov (United States)

Notni, Johannes; Šimeček, Jakub; Wester, Hans-Jürgen

2014-06-01

Given the wide application of positron emission tomography (PET), positron-emitting metal radionuclides have received much attention recently. Of these, gallium-68 has become particularly popular, as it is the only PET nuclide commercially available from radionuclide generators, therefore allowing local production of PET radiotracers independent of an on-site cyclotron. Hence, interest in optimized bifunctional chelators for the elaboration of (68) Ga-labeled bioconjugates has been rekindled as well, resulting in the development of improved triazacyclononane-triphosphinate (TRAP) ligand structures. The most remarkable features of these ligands are unparalleled selectivity for Ga(III) , rapid Ga(III) complexation kinetics, extraordinarily high thermodynamic stability, and kinetic inertness of the respective Ga(III) chelates. As a result, TRAP chelators exhibit very favorable (68) Ga-labeling properties. Based on the scaffolds NOPO (1,4,7-triazacyclononane-1,4-bis[methylene(hydroxymethyl)phosphinic acid]-7-[methylene(2-carboxyethyl)phosphinic acid]) and TRAP-Pr, tailored for convenient preparation of (68) Ga-labeled monomeric and multimeric bioconjugates, a variety of novel (68) Ga radiopharmaceuticals have been synthesized. These include bisphosphonates, somatostatin receptor ligands, prostate-specific membrane antigen (PSMA)-targeting peptides, and cyclic RGD pentapeptides, for in vivo PET imaging of bone, neuroendocrine tumors, prostate cancer, and integrin expression, respectively. Furthermore, TRAP-based (68) Ga-labeled gadolinium(III) complexes have been proposed as bimodal probes for PET/MRI, and a cyclen-based analogue of TRAP-Pr has been suggested for the elaboration of targeted radiotherapeutics comprising radiolanthanide ions. Thus, polyazacycloalkane-based polyphosphinic acid chelators are a powerful toolbox for pharmaceutical research, particularly for the development of (68) Ga radiopharmaceuticals. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Cathodic electrogenerated chemiluminescence of aromatic Tb(III) chelates at polystyrene-graphite composite electrodes

International Nuclear Information System (INIS)

Salminen, Kalle; Grönroos, Päivi; Tuomi, Sami; Kulmala, Sakari

2017-01-01

Tb(III) chelates exhibit intense hot electron-induced electrogenerated chemiluminescence during cathodic polarization of metal/polystyrene-graphite (M/PG) electrodes in fully aqueous solutions. The M/PG working electrode provides a sensitive means for the determination of aromatic Tb(III) chelates at nanomolar concentration levels with a linear log-log calibration curve spanning more than five orders of magnitude. The charge transport and other properties of these novel electrodes were studied by electrochemiluminescence measurements and cyclic voltammetry. The present composite electrodes can by utilized both under pulse polarization and DC polarization unlike oxide-coated metal electrodes which do not tolerate cathodic DC polarization. The present cost-effective electrodes could be utilized e.g. in immunoassays where polystyrene is extensively used as a solid phase for various bioaffinity assays by using electrochemiluminescent Tb(III) chelates or e.g. Ru(bpy) 3 2+ as labels. - Highlights: • Generation of hydrated electrons at Polystyrene-graphite electrodes. • The insulating polystyrene layer on the outer electrode surface seems necessary. • Hydrated electrons are able to produce chemiluminescence. • Strongest signal and lowest std. dev. achieved at same graphite weight fraction.

Chelated Nitrogen-Sulphur-Codoped TiO2: Synthesis, Characterization, Mechanistic, and UV/Visible Photocatalytic Studies

Directory of Open Access Journals (Sweden)

Hayat Khan

2017-01-01

Full Text Available This study presents in detail the physicochemical, photoluminescent, and photocatalytic properties of carboxylic acid chelated nitrogen-sulphur-codoped TiO2. From the Fourier transform infrared spectroscopic study, it was revealed that the formate group formed bidentate bridging linkage while the acetate group coordinated in a bidentate chelating mode with a titanium precursor. In compliance with X-ray diffraction data, the anatase to rutile transformation temperature was extended due to carboxylic acid chelation and NS codoping. Raman analysis indicated four Raman peaks at 146, 392, 512, and 632 cm−1 for the precalcined chelated TiO2; on incorporation with NS dopants, an increase in Raman intensity for these peaks was recorded, indicating the structure stability of the anatase phase. Furthermore, X-ray photoelectron spectroscopic study revealed the presence of anionic doping of nitrogen and cationic doping of sulphur in the lattice of TiO2. When evaluating the UV-visible photodegradation rate of 4-chlorophenol, the modified TiO2 (NS0.06-TFA showed the highest photocatalytic activity. In connection with the activity tests, several scavenger agents were employed to elucidate the significance of the different reactive oxidizing species during the photocatalytic process. Moreover, the transfer pathways of photogenerated carriers and the photocatalytic reaction mechanism of modified TiO2 were also explained in detail.

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

Science.gov (United States)

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.

Diagnostic compositions containing a chelate of radioactive indium and 8-hydroxyquinoline

International Nuclear Information System (INIS)

Goedemans, W.T.

1981-01-01

There are disclosed aqueous, radioassaying solutions of a chelate of radioactive indium and an 8-hydroxyquinoline, having an essential absence of an organic solvent, e.g., alcohol or chloroform. The solutions are useful in radioassaying warmblooded animals. (author)

Fusaric acid induces a notochord malformation in zebrafish via copper chelation.

Science.gov (United States)

Yin, Emily S; Rakhmankulova, Malika; Kucera, Kaury; de Sena Filho, Jose Guedes; Portero, Carolina E; Narváez-Trujillo, Alexandra; Holley, Scott A; Strobel, Scott A

2015-08-01

Over a thousand extracts were tested for phenotypic effects in developing zebrafish embryos to identify bioactive molecules produced by endophytic fungi. One extract isolated from Fusarium sp., a widely distributed fungal genus found in soil and often associated with plants, induced an undulated notochord in developing zebrafish embryos. The active compound was isolated and identified as fusaric acid. Previous literature has shown this phenotype to be associated with copper chelation from the active site of lysyl oxidase, but the ability of fusaric acid to bind copper ions has not been well described. Isothermal titration calorimetry revealed that fusaric acid is a modest copper chelator with a binding constant of 4.4 × 10(5) M(-1). These results shed light on the toxicity of fusaric acid and the potential teratogenic effects of consuming plants infected with Fusarium sp.

Post-Digestion Liquor Treatment in the Method Combining Chemical Precipitation with Reverse Osmosis

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Kuglarz Mariusz

2014-12-01

Full Text Available The aim of the study was to develop an effective treatment of post-digestion liquors highly-loaded with biogenic and organic substances. The scope of the research project encompassed: mesophilic anaerobic digestion of waste activated sludge (WAS as well as the treatment of post-digestion liquors, coming from the most appropriate HRT value of 25 days, in the process of ammonium magnesium phosphate (struvite precipitation targeted at ammonia nitrogen binding and a subsequent reverse osmosis (RO process. It was established that the method combining chemical precipitation and high-pressure filtration ensures a high degree of contaminants removal allowing for a direct release of treated liquors into the natural reservoir. However, in order to decrease the residual NH4+ concentration (6.1 mg NH4+/dm3 in the purified post-digestion liquors below the level allowing for a direct release to the natural reservoir, it turned out to be necessary to apply increased molar ratio of magnesium and phosphates (Mg:NH4+: PO43-= 1.5:1:1.5.

Side effects of Deferasirox Iron Chelation in Patients with Beta Thalassemia Major or Intermedia

Directory of Open Access Journals (Sweden)

Murtadha Al-Khabori

2013-03-01

Full Text Available Objectives: Chelating agents remain the mainstay in reducing the iron burden and extending patient survival in homozygous beta-thalassemia but adverse and toxic effects may increase with the institution and long term use of this essential therapy. This study aimed to estimate the incidence of deferasirox (DFX side effects in patients with thalassemia major or intermedia.Methods: A retrospective study of 72 patients (mean age: 20.3±0.9 yrs; 36 male, 36 female with thalassemia major or intermedia treated at Sultan Qaboos University Hospital, Oman, was performed to assess the incidence of side effects related to deferasirox over a mean of 16.7 month follow-up period.Results: Six patients experienced rashes and 6 had gastro-intestinal upset. DFX was discontinued in 18 patients for the following reasons: persistent progressive rise(s in serum creatinine (7 patients; 40% mean serum creatinine rise from baseline, feeling unwell (2, severe diarrhea (1, pregnancy (1, death unrelated to chelator (2 and rise in serum transaminases (2. Three patients were reverted to desferoxamine and deferiprone combination therapy as DFX was no longer biochemically effective after 18 months of therapy. There was no correlation between baseline serum ferritin and serum creatinine or a rise in serum creatinine. Cardiac MRI T2* did not change with DFX therapy. However, there was an improvement in liver MRI T2* (p=0.013.Conclusion: Renal side effects related to deferasirox appear to be higher than those reported in published clinical trials. Further larger studies are required to confirm these findings.

Effects of iron(III)chelates on the solubility of heavy metals in calcareous soils

Energy Technology Data Exchange (ETDEWEB)

Ylivainio, Kari, E-mail: kari.ylivainio@mtt.f [Department of Applied Chemistry and Microbiology, FIN-00014 University of Helsinki (Finland)

2010-10-15

In this study I evaluated the effects of complexing agents on the solubility of heavy metals in an incubation experiment up to 56 days when complexing agents were applied as Fe-chelates (Fe-EDDS(S,S), Fe-EDDS(mix), Fe-EDTA and Fe-EDDHA) on calcareous soils at a level sufficient to correct Fe chlorosis (0.1 mmol kg{sup -1}). Of these ligands, EDDHA was the most efficient in keeping Fe in water-soluble form, and EDDS increased the solubility of Cu and Zn most, and only EDTA increased the solubility of Cd and Pb. EDTA increased the solubility of Ni steadily during the incubation period, equalling about 5-8% of the added EDTA concentration. [S,S]-EDDS was biodegraded within 56 days, whereas EDDS(mix) was less biodegradable. Ni-chelates were the most recalcitrant against biodegradation. The study shows that even a moderate input of chelates to soil increases the solubility of toxic heavy metals and their risk of leaching. - When correcting Fe chlorosis Fe-EDDS causes lower environmental concern than Fe-EDTA.

Effects of iron(III)chelates on the solubility of heavy metals in calcareous soils

International Nuclear Information System (INIS)

Ylivainio, Kari

2010-01-01

In this study I evaluated the effects of complexing agents on the solubility of heavy metals in an incubation experiment up to 56 days when complexing agents were applied as Fe-chelates (Fe-EDDS(S,S), Fe-EDDS(mix), Fe-EDTA and Fe-EDDHA) on calcareous soils at a level sufficient to correct Fe chlorosis (0.1 mmol kg -1 ). Of these ligands, EDDHA was the most efficient in keeping Fe in water-soluble form, and EDDS increased the solubility of Cu and Zn most, and only EDTA increased the solubility of Cd and Pb. EDTA increased the solubility of Ni steadily during the incubation period, equalling about 5-8% of the added EDTA concentration. [S,S]-EDDS was biodegraded within 56 days, whereas EDDS(mix) was less biodegradable. Ni-chelates were the most recalcitrant against biodegradation. The study shows that even a moderate input of chelates to soil increases the solubility of toxic heavy metals and their risk of leaching. - When correcting Fe chlorosis Fe-EDDS causes lower environmental concern than Fe-EDTA.

Effects of iron(III)chelates on the solubility of heavy metals in calcareous soils.

Science.gov (United States)

Ylivainio, Kari

2010-10-01

In this study I evaluated the effects of complexing agents on the solubility of heavy metals in an incubation experiment up to 56 days when complexing agents were applied as Fe-chelates (Fe-EDDS(S,S), Fe-EDDS(mix), Fe-EDTA and Fe-EDDHA) on calcareous soils at a level sufficient to correct Fe chlorosis (0.1 mmol kg(-1)). Of these ligands, EDDHA was the most efficient in keeping Fe in water-soluble form, and EDDS increased the solubility of Cu and Zn most, and only EDTA increased the solubility of Cd and Pb. EDTA increased the solubility of Ni steadily during the incubation period, equalling about 5-8% of the added EDTA concentration. [S,S]-EDDS was biodegraded within 56 days, whereas EDDS(mix) was less biodegradable. Ni-chelates were the most recalcitrant against biodegradation. The study shows that even a moderate input of chelates to soil increases the solubility of toxic heavy metals and their risk of leaching. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

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

International Nuclear Information System (INIS)

Clistenes do Nascimento, Williams A.; Amarasiriwardena, Dula; Xing, Baoshan

2006-01-01

Chemically assisted phytoremediation has been developing to induce accumulation of metals by high biomass plants. Synthetic chelates have shown high effectiveness to reach such a goal, but they pose serious drawbacks in field application due to the excessive amount of metals solubilized. We compared the performance of synthetic chelates with naturally occurring low molecular weight organic acids (LMWOA) in enhancing 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. - Organic acids can be as efficient as synthetic chelates for use in phytoextraction of multi-metal contaminated soils

Effects of hydroxycinnamic acids on blue color expression of cyanidin derivatives and their metal chelates.

Science.gov (United States)

Sigurdson, G T; Robbins, R J; Collins, T M; Giusti, M M

2017-11-01

Mechanisms to recreate many anthocyanin blue hues in nature are not fully understood, but interactions with metal ions and phenolic compounds are thought to play important roles. Bluing effects of hydroxycinnamic acids on cyanidin and chelates were investigated by addition of the acids to triglycosylated cyanidin (0-50×[anthocyanin]) and by comparison to hydroxycinnamic acid monoacylated and diacylated Cy fractions by spectrophotometry (380-700nm) and colorimetry in pH 5-8. With no metal ions, λ max and absorbance was greatest for cyanidin with diacylation>monoacylation>increasing [acids]. Hydroxycinnamic acids added to cyanidin solutions weakly impacted color characteristics (ΔEacid attachment) resulted in ΔE 5-15. Triglycosylated cyanidin expressed blue color (pH 7-8), suggesting glycosylation pattern also plays a role. Al 3+ chelation increased absorbance 2-42× and λ max ≳40nm (pH 5-6) compared to added hydroxycinnamic acids. Metal chelation and aromatic diacylation resulted in the most blue hues. Copyright © 2017 Elsevier Ltd. All rights reserved.

Assessment of the body burden of chelatable lead: a model and its application to lead workers.

Science.gov (United States)

Araki, S; Ushio, K

1982-01-01

A hypothetical model was introduced to estimate the body burden of chelatable lead from the mobilisation yield of lead by calcium disodium ethylenediamine tetra-acetate (CaEDTA). It was estimated that, on average, 14 and 19% of the body burden was mobilised into the urine during the 24 hours after an injection of 53.4 mumol (20 mg) and 107 mumol (40 mg) CaEDTA per kg bodyweight, respectively. The body burden of chelatable lead ranged from 4 mumol (0.8 mg) to 120 mumol (24.9 mg) (mean 37 mumol (7.7 mg) in lead workers with blood lead concentrations of 0.3-2.9 mumol/kg (6-60 microgram/100 g) (mean 1.4 mumol/kg (29 microgram/100 g)). There were linear relationships between blood lead concentrations and body burden of chelatable lead on a log scale. PMID:6802167

Fluorescence detection of flavonols in HPLC by postcolumn chelation with aluminum

NARCIS (Netherlands)

Hollman, Peter C H; Van Trijp, J. M P; Buysman, Michel N C P

1996-01-01

Flavonols are dietary antioxidants which may prevent coronary heart disease. To be able to study absorption of flavonols in humans, we developed a postcolumn derivatization with aluminum for HPLC with fluorescence detection. Variables governing postcolumn chelation, such as water content, buffer,

Bis-ligated Ti and Zr complexes of chelating N-heterocyclic carbenes

KAUST Repository

El-Batta, Amer; Waltman, Andrew W.; Grubbs, Robert H.

2011-01-01

In this communication we report the synthesis of novel titanium and zirconium complexes ligated by bidentate "salicylaldimine-like" N-heterocyclic carbenes (NHC). Double addition of the NHC chelate to either TiCl4(thf)2 or ZrCl4 forms bis

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

Science.gov (United States)

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.

Photoacoustic imaging in scattering media by combining a correlation matrix filter with a time reversal operator.

Science.gov (United States)

Rui, Wei; Tao, Chao; Liu, Xiaojun

2017-09-18

Acoustic scattering medium is a fundamental challenge for photoacoustic imaging. In this study, we reveal the different coherent properties of the scattering photoacoustic waves and the direct photoacoustic waves in a matrix form. Direct waves show a particular coherence on the antidiagonals of the matrix, whereas scattering waves do not. Based on this property, a correlation matrix filter combining with a time reversal operator is proposed to preserve the direct waves and recover the image behind a scattering layer. Both numerical simulations and photoacoustic imaging experiments demonstrate that the proposed approach effectively increases the image contrast and decreases the background speckles in a scattering medium. This study might improve the quality of photoacoustic imaging in an acoustic scattering environment and extend its applications.

Synthesis, Characterization and Chelating Properties of 4-Butyrylsemicarbazone-1-phenyl-3-methyl-2-pyrazolin-5-one

Directory of Open Access Journals (Sweden)

J. D. Patel

2010-01-01

Full Text Available 4-Butyrylsemicarbazone-1-phenyl-3-methyl-2-pyrazolin-5-one (BUMP-SC was prepared and its metal chelates of Cu2+, Ni2+, Co2+, Mn2+, Fe2+, Fe3+, Cr3+, UO2 and OV were prepared. The ligands and its chelates were characterized by elemental analysis, metal:ligand (M:L stoichiometry, IR-electronic spectral studies and magnetic properties. The compounds also were screened for their antimicrobial activity.

Combustion of gadolinium and dysprosium chelates as a cellular integrity marker in MR imaging

International Nuclear Information System (INIS)

Ericsson, A.; Bach-Gansmo, T.; Niklasson, F.; Hemmingsson, A.

1995-01-01

A combination of gadolinium (Gd) and dysprosium (Dy) chelates was investigated as a potential marker of cell-membrane integrity by means of a double-contrast effect in MR imaging. Blood samples with varying hematocrit (Hct) levels containing intact or lysed cells were used as model systems. With intact cells, the agents were assumed to be distributed solely extracellularly and the highest Hct studied (69%) was assumed to mimic the ratio of extracellular to intracellular water in tissue. The combined effect on image intensity of Gd (in a concentration corresponding to 0.2 mmol/kg b.w. in humans) and Dy (0.6 mmol/kg b.w.) applied simultaneously was a marked difference in signal intensity between samples with intact and lysed cells in both the T1- and T2-weighted spin-echo images with a corresponding increase in the contrast-to-noise ratio. This was the result of a T1 reduction caused by Gd with a negligible Dy susceptibility effect in areas with lysed cells. On the other hand, the Dy susceptibility effect (i.e. reduced apparent T2) dominated in areas with intact cells. Thus, the combination of Gd and Dy may serve as a marker of cell-membrane integrity in MR examinations. (orig.)

Soft chelating irrigation protocol optimizes bonding quality of Resilon/Epiphany root fillings.

Science.gov (United States)

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

2008-06-01

This study was designed to test the impact of either a strong (MTAD) or a soft (1-hydroxyethylidene-1, 1-bisphosphonate [HEPB]) chelating solution on the bond strength of Resilon/Epiphany root fillings. Both 17% EDTA and the omission of a chelator in the irrigation protocol were used as reference treatments. Forty extracted human upper lateral incisors were prepared using different irrigation protocols (n = 10): G1: NaOCl, G2: NaOCl + 17% EDTA, G3: NaOCl + BioPure MTAD (Dentsply/Tulsa, Tulsa, OK), and G4: NaOCl + 18% HEPB. The teeth were obturated and then prepared for micropush-out assessment using root slices of 1 mm thickness. Loading was performed on a universal testing machine at a speed of 0.5 mm/min. One-way analysis of variance and Tukey multiple comparisons were used to compare the results among the experimental groups. EDTA- and MTAD-treated samples revealed intermediate bond strength (0.3-3.6 MPa). The lowest bond strengths were achieved in NaOCl-treated samples (0.3-1.2 MPa, p < 0.05). The highest bond strength was reached in the HEBP-treated samples (3.1-6.1 MPa, p < 0.05). Under the present in vitro conditions, the soft chelating irrigation protocol (18% HEBP) optimized the bonding quality of Resilon/Epiphany (Resilon Research LLC, Madison, CT) root fillings.

The attachment of metal-chelating groups to proteins: tagging of albumin by diazonium coupling and use of the products as radiopharmaceuticals

International Nuclear Information System (INIS)

Leung, C.S.H.; Meares, C.F.; Goodwin, D.A.

1978-01-01

The ability to attach firmly chelated metal ions or powerful chelating agents to sites on biological molecules can enhance the utility of a number of physical techniques now used in the study of biological systems. A 'bifunctional' chelating agent, containing both an EDTA group and a diazonium group, has been prepared and coupled to human serum albumin. The extent of labeling under various conditions and the amino-acid sidechains labeled have been investigated. The reaction of protein-bound chelating groups with added metal ions has been studied, with the finding that only about 40-50% of these groups are available to bind metal ions. Proteolysis of the products leads to recovery of full metal-binding capacity. Properties of the products in vivo are discussed. (author)

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

Science.gov (United States)

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.

A simplified suite of methods to evaluate chelator conjugation of antibodies: effects on hydrodynamic radius and biodistribution

International Nuclear Information System (INIS)

Al-Ejeh, Fares; Darby, Jocelyn M.; Thierry, Benjamin; Brown, Michael P.

2009-01-01

Introduction: Antibodies covalently conjugated with chelators such as 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) are required for radioimmunoscintigraphy and radioimmunotherapy, which are of growing importance in cancer medicine. Method: Here, we report a suite of simple methods that provide a preclinical assessment package for evaluating the effects of DOTA conjugation on the in vitro and in vivo performance of monoclonal antibodies. We exemplify the use of these methods by investigating the effects of DOTA conjugation on the biochemical properties of the DAB4 clone of the La/SSB-specific murine monoclonal autoantibody, APOMAB (registered) , which is a novel malignant cell death ligand. Results: We have developed a 96-well microtiter-plate assay to measure directly the concentration of DOTA and other chelators in antibody-chelator conjugate solutions. Coupled with a commercial assay for measuring protein concentration, the dual microtiter-plate method can rapidly determine chelator/antibody ratios in the same plate. The biochemical properties of DAB4 immunoconjugates were altered as the DOTA/Ab ratio increased so that: (i) mass/charge ratio decreased; (ii) hydrodynamic radius increased; (iii) antibody immunoactivity decreased; (iv) rate of chelation of metal ions and specific radioactivity both increased and in vivo, (v) tumor uptake decreased as nonspecific uptake by liver and spleen increased. Conclusion: This simplified suite of methods readily identifies biochemical characteristics of the DOTA-immunoconjugates such as hydrodynamic diameter and decreased mass/charge ratio associated with compromised immunotargeting efficiency and, thus, may prove useful for optimizing conjugation procedures in order to maximize immunoconjugate-mediated radioimmunoscintigraphy and radioimmunotherapy.

Detoxication and removal of uranium by phenolic chelating agents

International Nuclear Information System (INIS)

Luo Meichu; Chen Guibao; Li Landi

1992-01-01

The use of phenolic chelating agents for detoxication and removal of uranyl nitrate in mice and rats is reported. Antidotal test: 8102, 7601 and 811 were given 2 mM/kg subcutaneously to mice and 1 mM/kg intramuscularly to rats when the animals were injected i.p. with different doses (100-500 mg/kg) of uranyl nitrate. The results showed that the antidotal effects of 8102 and 7601 were better than 811 in augmenting survival, survival time (day) and renal factor (kidney weight/body weight x100). 8102 was superior to 7601 against higher dose of uranyl nitrate intoxication. Removal test: five phenolic chelating agents (8102, 7601, 811, 7603 and 8307) were studied in rats. The results obtained demonstrated that 8102 and 7601 were better than 811, 7603 and 8307 in increasing U excretion in the urine after acute uranyl nitrate intoxication. The effects of different doses (300-1000 μM/kg) of 8102 was superior to 7601 in increasing U excretion in the urine and decreasing U deposition in the tissues. The toxicity and dose of 8102 in treating uranium intoxication are discussed

Synthesis of LaNiO3 perovskite type by chelating precursor method using EDTA: optimization of chelating content

International Nuclear Information System (INIS)

Santos, Jose Carlos dos; Pedrosa, Anne Michelle Garrido; Mesquita, Maria Eliane; Souza, Marcelo Jose Barros de

2011-01-01

The perovskites are strategic materials due their catalytic, electronic and magnetic properties. These properties are influenced by the calcination and synthesis conditions. In this work was carried out the synthesis of LaNiO 3 perovskite type by chelating precursor method using EDTA and also was studied the optimization of the EDTA content in the synthesis. The synthesized materials were characterized by X-ray diffraction (XRD), thermal gravimetric analysis (TG) and Infrared Spectroscopy (FTIR). In the optimization of the EDTA content the lowest ratio of metal / EDTA used was 1.0 / 0.1, where it was possible to obtain monophasic perovskite. (author)

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.

Science.gov (United States)

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

Flavonoids-induced accumulation of hypoxia-inducible factor (HIF)-1alpha/2alpha is mediated through chelation of iron.

Science.gov (United States)

Park, Sung-Soo; Bae, Insoo; Lee, Yong J

2008-04-15

Hypoxia-inducible factor-1 alpha (HIF-1alpha) is the regulatory subunit of the heterodimeric transcription factor HIF-1 that is the key regulator of cellular response to low oxygen tension. Under normoxic conditions, HIF-1alpha is continuously degraded by the ubiquitin-proteasome pathway through pVHL (von Hippel-Lindau tumor suppressor protein). Under hypoxic conditions, HIF-1alpha is stabilized and induces the transcription of HIF-1 target genes. Quercetin, a flavonoid with anti-oxidant, anti-inflammatory, and kinase modulating properties, has been found to induce HIF-1alpha accumulation and VEGF secretion in normoxia. In this study, the molecular mechanisms of quercetin-mediated HIF-1alpha accumulation were investigated. Previous studies have shown that, in addition to being induced by hypoxia, HIF-1alpha can be induced through the phosphatidylinositol 3-kinase (PI3K)/Akt and p53 signaling pathways. But our study revealed, through p53 mutant-type as well as p53 null cell lines, that neither the PI3K/Akt nor the p53 signaling pathway is required for quercetin-induced HIF-1alpha accumulation. And we observed that HIF-1alpha accumulated by quercetin is not ubiquitinated and the interaction of HIF-1alpha with pVHL is reduced, compared with HIF-1alpha accumulated by the proteasome inhibitor MG132. The use of quercetin's analogues showed that only quercetin and galangin induce HIF-1/2alpha accumulation and this effect is completely reversed by additional iron ions. This is because quercetin and galangin are able to chelate cellular iron ions that are cofactors of HIF-1/2alpha proline hydroxylase (PHD). These data suggest that quercetin inhibits the ubiquitination of HIF-1/2alpha in normoxia by hindering PHD through chelating iron ions.

Flue gas desulfurization/denitrification using metal-chelate additives

Science.gov (United States)

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

1985-08-05

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

Self-assembled polymeric chelate nanoparticles as potential theranostic agents

Czech Academy of Sciences Publication Activity Database

Škodová, Michaela; Černoch, Peter; Štěpánek, Petr; Chánová, Eliška; Kučka, Jan; Kálalová, Zuzana; Kaňková, Dana; Hrubý, Martin

2012-01-01

Roč. 13, č. 18 (2012), s. 4244-4250 ISSN 1439-4235 R&D Projects: GA ČR GPP207/10/P054; GA ČR GA202/09/2078; GA ČR GAP304/12/0950 Institutional research plan: CEZ:AV0Z40500505 Institutional support: RVO:61389013 Keywords : chelate s * nanoparticles * polymers Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.349, year: 2012

XAS studies of the effectiveness of iron chelating treatments of Mary Rose timbers

International Nuclear Information System (INIS)

Berko, A; Schofield, E J; Chadwick, A V; Smith, A D; Jones, A M; Mosselmans, J F W

2009-01-01

The oxidation of sulfur in marine archaeological timbers under museum storage conditions is a recently identified problem, particularly for major artefacts such as historic ships excavated from the seabed. Recent work on the Vasa has stressed the role of iron in catalysing the oxidative degradation of the wood cellulose and the polyethylene glycols used to restore mechanical integrity to the timbers. In developing new treatment protocols for the long term preservation of Henry VIII of England's flagship, the Mary Rose, we are investigating the potential of chelating agents to neutralise and remove the iron products from the ships timbers. We have explored the use of aqueous solutions of chelating agents of calcium phytate, ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA) and ammonium citrate to extract the iron compounds. All of these solutions exhibit some level of iron removal; however the key is to find the most effective concentration at pH of around 7 of the reagent solution, to minimise the treatment time and find the most cost-effective treatment for the whole of the Mary Rose hull. Fe K-edge XAFS data from samples of Mary Rose timbers, before and after treatment by the chelating agents mentioned has been collected. The data collected provide valuable insights into the effectiveness of the treatment solutions.

Comparison of Three Analytical Methods for Separation of Mineral and Chelated Fraction from an Adulterated Zn-EDTA Fertilizer

International Nuclear Information System (INIS)

Khan, M.S.; Qazi, M.A.; Khan, N.A.; Mian, S.M.; Ahmed, N.; Ahmed, N.

2013-01-01

Summary: Different analytical procedures are being employed in the world to quantify the chelated portion in a Zn-EDTA fertilizer. Agriculture Department, Government of the Punjab is following Shahid's analytical method in this regard. This method is based on Ion-chromatography (IC) that separates the mineral zinc (Zn) from an adulterated Zn-EDTA fertilizer sample i.e. mixture of mineral and chelated Zn fractions. To find out its effectiveness and suitability, this comparative study was carried out by analyzing adulterated, non-adulterated Zn-EDTA standard and Zn-EDTA samples taken from market in thrice following three methods namely Shahid's (IC) analytical method, Atomic Absorption Spectrophotometric (AAS) method based on the principle of precipitating the mineral Zn fraction at high pH value by using alkali solution of suitable concentration and analysis of filtrate containing only chelated fraction and Association of Official Analytical Chemists (AOAC) method FM-841 respectively. Adulterated Zn-EDTA samples were prepared by mixing of known quantity of mineral Zn with chelated Zn-EDTA standard. The results showed that Shahid's analytical method and AAS method, both successfully estimated the chelated fraction. The AOAC FM-841 method was insensitive to put a ceiling on the mineral fraction hence did not furnish the reliable results. The Shahid's analytical method was selected being equallyeffective to produce reliable results both for solid and liquid Zn-EDTA samples. The AAS method was comparable in only liquid samples. (author)

Effect of inorganic chelate of zinc and restaurant residual oil added ...

African Journals Online (AJOL)

Effect of inorganic chelate of zinc and restaurant residual oil added to feed mixture ... The interaction effects of RRO and ZnO did not result to a significant change in ... Therefore, the effects of RRO deteriorated the quality of meat by raising the ...

Water-soluble chelating polymers for removal of actinides from wastewater

International Nuclear Information System (INIS)

Jarvinen, G.D.

1997-01-01

Polymer filtration is a technology under development to selectively recover valuable or regulated metal ions from process or wastewaters. The technology uses water-soluble chelating polymers that are designed to selectively bind with metal ions in aqueous solutions. The polymers have a sufficiently large molecular weight that they can be separated and concentrated using available ultrafiltration (UF) technology. The UF range is generally considered to include molecular weights from about 3000 to several million daltons and particles sizes of about 2 to 1000 nm. Water and smaller unbound components of the solution pass freely through the UF membrane. The polymers can then be reused by changing the solution conditions to release the metal ions that are recovered in concentrated form for recycle or disposal. Some of the advantages of polymer filtration relative to technology now in use are rapid binding kinetics, high selectivity, low energy and capital costs, and a small equipment footprint. Some potential commercial applications include electroplating rinse waters, photographic processing, nuclear power plant cooling water; remediation of contaminated soils and groundwater; removal of mercury contamination; and textile, paint and dye production. The purpose of this project is to evaluate this technology to remove plutonium, americium, and other regulated metal ions from various process and waste streams found in nuclear facilities. The work involves preparation of the water-soluble chelating polymers; small-scale testing of the chelating polymer systems for the required solubility, UF properties, selectivity and binding constants; followed by an engineering assessment at a larger scale to allow comparison to competing separation technologies. This project focuses on metal-ion contaminants in waste streams at the Plutonium Facility and the Waste Treatment Facility at LANL. Potential applications at other DOE facilities are also apparent

Water-soluble chelating polymers for removal of actinides from wastewater

Energy Technology Data Exchange (ETDEWEB)

Jarvinen, G.D. [Los Alamos National Lab., NM (United States)

1997-10-01

Polymer filtration is a technology under development to selectively recover valuable or regulated metal ions from process or wastewaters. The technology uses water-soluble chelating polymers that are designed to selectively bind with metal ions in aqueous solutions. The polymers have a sufficiently large molecular weight that they can be separated and concentrated using available ultrafiltration (UF) technology. The UF range is generally considered to include molecular weights from about 3000 to several million daltons and particles sizes of about 2 to 1000 nm. Water and smaller unbound components of the solution pass freely through the UF membrane. The polymers can then be reused by changing the solution conditions to release the metal ions that are recovered in concentrated form for recycle or disposal. Some of the advantages of polymer filtration relative to technology now in use are rapid binding kinetics, high selectivity, low energy and capital costs, and a small equipment footprint. Some potential commercial applications include electroplating rinse waters, photographic processing, nuclear power plant cooling water; remediation of contaminated soils and groundwater; removal of mercury contamination; and textile, paint and dye production. The purpose of this project is to evaluate this technology to remove plutonium, americium, and other regulated metal ions from various process and waste streams found in nuclear facilities. The work involves preparation of the water-soluble chelating polymers; small-scale testing of the chelating polymer systems for the required solubility, UF properties, selectivity and binding constants; followed by an engineering assessment at a larger scale to allow comparison to competing separation technologies. This project focuses on metal-ion contaminants in waste streams at the Plutonium Facility and the Waste Treatment Facility at LANL. Potential applications at other DOE facilities are also apparent.

Hydrolysis of Some C,N-Chelated Organotin(IV) Species Used in Catalysis

OpenAIRE

Švec, P.

2012-01-01

This work deals with the reactivity of the selected C, N-chelated organotin (IV) species towards cyclohexene oxide, ethylene carbonate, and CO2. Structure of organotin(IV) hydrolytic products isolated from respective reaction mixtures was described.

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.

Science.gov (United States)

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.

The Correction of a Secondary Bilateral Cleft Lip Nasal Deformity Using Refined Open Rhinoplasty with Reverse-U Incision, V-Y Plasty, and Selective Combination with Composite Grafting: Long-term Results

Directory of Open Access Journals (Sweden)

Byung Chae Cho

2012-05-01

Full Text Available BackgroundThis article presents long-term outcomes after correcting secondary bilateral cleft lip nasal deformities using a refined reverse-U incision and V-Y plasty or in combination with a composite graft in order to elongate the short columella.MethodsA total of forty-six patients underwent surgery between September 1996 and December 2008. The age of the patients ranged from 3 to 19 years of age. A bilateral reverse-U incision and V-Y plasty were used in 24 patients. A composite graft from the helical root was combined with a bilateral reverse-U incision in the 22 patients who possessed a severely shortened columella. The follow-up period ranged between 2 and 10 years.ResultsA total of 32 patients out of 46 were evaluated postoperatively. The average columella length was significantly improved from an average of 3.7 mm preoperatively to 8.5 mm postoperatively. The average ratio of the columella height to the alar base width was 0.18 preoperatively and 0.29 postoperatively. The postoperative basal and lateral views revealed a better shape of the nostrils and columella. The elongated columella, combined with a composite graft, presented good maintenance of the corrected position with no growth disturbance. A composite graft showed color mismatching in several patients. Twenty-six patients demonstrated no alar-columella web deformity and satisfactory symmetry of the nostrils. Four patients experienced a drooping and overhanging of the corrected alar-columella web.ConclusionsA bilateral reverse-U incision with V-Y plasty or in combination with a composite graft was effective in correcting secondary bilateral cleft lip nasal deformity.

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

Science.gov (United States)

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.

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

Science.gov (United States)

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 ions). The monolithic chelating ion-exchanger was applied to the separation of alkaline earth and transition metal ions spiked in natural and potable waters.

A Powerful Mitochondria-Targeted Iron Chelator Affords High Photoprotection against Solar Ultraviolet A Radiation.

Science.gov (United States)

Reelfs, Olivier; Abbate, Vincenzo; Hider, Robert C; Pourzand, Charareh

2016-08-01

Mitochondria are the principal destination for labile iron, making these organelles particularly susceptible to oxidative damage on exposure to ultraviolet A (UVA, 320-400 nm), the oxidizing component of sunlight. The labile iron-mediated oxidative damage caused by UVA to mitochondria leads to necrotic cell death via adenosine triphosphate depletion. Therefore, targeted removal of mitochondrial labile iron via highly specific tools from these organelles may be an effective approach to protect the skin cells against the harmful effects of UVA. In this work, we designed a mitochondria-targeted hexadentate (tricatechol-based) iron chelator linked to mitochondria-homing SS-like peptides. The photoprotective potential of this compound against UVA-induced oxidative damage and cell death was evaluated in cultured primary skin fibroblasts. Our results show that this compound provides unprecedented protection against UVA-induced mitochondrial damage, adenosine triphosphate depletion, and the ensuing necrotic cell death in skin fibroblasts, and this effect is fully related to its potent iron-chelating property in the organelle. This mitochondria-targeted iron chelator has therefore promising potential for skin photoprotection against the deleterious effects of the UVA component of sunlight. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Influence of the soil/solution ratio, interaction time, and extractant on the evaluation of iron chelate sorption/desorption by soils.

Science.gov (United States)

Hernández-Apaolaza, Lourdes; Lucena, Juan J

2011-03-23

Synthetic Fe chelates are the most efficient agricultural practice to control Fe deficiency in crops, EDTA/Fe3+ and o,o-EDDHA/Fe3+ being the most commonly used. Their efficacy as Fe sources and carriers in soils can be severely limited by their retention on it. The aim of this work is to evaluate the possible bias introduced in the studies of the iron chelate retention by soils. For that purpose, results obtained for EDTA and EDDHA iron chelates from two batch studies with different soil/solution ratios were compared with data obtained for a leaching column experiment. Moreover, different extractants were tested to study the o,o-EDDHA/Fe3+ and o,p-EDDHA/Fe3+ desorption from a calcareous soil, and also the effect of the interaction time in their retention process has been evaluated. In summary, the mobility through a calcareous soil of the studied iron chelates differs greatly depending on the type of iron chelate and also on the procedure used to evaluate the retention and the soil/solution ratio used. In general, the leaching column method is preferred because the achieved conclusions are more representative of the natural conditions, but batch methods are very useful as a preliminary experiment, especially one with a high soil/solution ratio. The iron chelate desorption could be quantified by using a sequential extraction with water, sodium sulfate, and DTPA as extractants. Under the experimental conditions used in this study, o,o-EDDHA/Fe3+ retention increased with interaction time.

Comparison of reversal and adverse effects of sugammadex and combination of -Anticholinergic-Anticholinesterase agents in pediatric patients

Directory of Open Access Journals (Sweden)

Çiğdem Özgün

2014-01-01

Full Text Available Background: We aimed to compare clinical effects of sugammadex versus combination of anticholinergic-anticholinesterase agents for reversing of nondepolarizing neuromuscular block in pediatric patients. Materials and Methods: A total of 60 pediatric patients whom should be performed general anesthesia in the supine position were enrolled to this randomized double-blinded clinical trial. Fentanyl 1 μg/kg, propofol 2 mg/kg, rocuronium 0.6 mg/kg were used in induction and sevofluran, 50% O 2 -50% N 2 O in maintenance of anesthesia. Neuromuscular conductions were assessed by train of four (TOF-Watch SX (Organon, Schering-Plough, Ireland acceleromyograph. Patients were intubated at the moment of TOF 0. At the end of the operation emergence of T2 point was replied by 2 mg/kg sugammadex administration in group 1 and 0.06 mg/kg neostigmine +0.02 mg/kg atropine in group 2. At the moment of T0.9 inhalation, gases were ceased, and patients were extubated. Hemodynamic alterations, access to T0.9, extubation time, recovery parameters, drug consumptions and adverse effects were recorded. Results: Train of four scores showed a lesser increase in group 2 than group 1 from 15 th s to 30 th min during post reverse period (from 6.9 ± 6.4 to 91.7 ± 7.2 in group 2 vs. from 35.4 ± 21.4 to 99.5 ± 1.0 in group 1 (p < 0.0004. Group 1 patients exhibited much more complete muscle strength rates than group 2 (P < 0.001. T0.9 and extubation times were significantly longer in group 2 than group 1 (P < 0.001. Comparison of adverse effects yielded no difference. Conclusion: Sugammadex can be considered as a safe agent in order to reverse neuromuscular block in pediatric patients.

Multiple reversal olfactory learning in honeybees

Directory of Open Access Journals (Sweden)

Theo Mota

2010-07-01

Full Text Available In multiple reversal learning, animals trained to discriminate a reinforced from a non-reinforced stimulus are subjected to various, successive reversals of stimulus contingencies (e.g. A+ vs. B-, A- vs. B+, A+ vs. B-. This protocol is useful to determine whether or not animals learn to learn and solve successive discriminations faster (or with fewer errors with increasing reversal experience. Here we used the olfactory conditioning of proboscis extension reflex to study how honeybees Apis mellifera perform in a multiple reversal task. Our experiment contemplated four consecutive differential conditioning phases involving the same odors (A+ vs. B- to A- vs. B+ to A+ vs. B- to A- vs. B+. We show that bees in which the weight of reinforced or non-reinforced stimuli was similar mastered the multiple olfactory reversals. Bees which failed the task exhibited asymmetric responses to reinforced and non-reinforced stimuli, thus being unable to rapidly reverse stimulus contingencies. Efficient reversers did not improve their successive discriminations but rather tended to generalize their choice to both odors at the end of conditioning. As a consequence, both discrimination and reversal efficiency decreasedalong experimental phases. This result invalidates a learning-to-learn effect and indicates that bees do not only respond to the actual stimulus contingencies but rather combine these with an average of past experiences with the same stimuli.  

Chelating polymeric beads as potential therapeutics for Wilson’s disease

Czech Academy of Sciences Publication Activity Database

Mattová, J.; Poučková, P.; Kučka, Jan; Škodová, Michaela; Vetrík, Miroslav; Štěpánek, Petr; Urbánek, P.; Petřík, M.; Nový, Z.; Hrubý, Martin

2014-01-01

Roč. 62, 1 October (2014), s. 1-7 ISSN 0928-0987 R&D Projects: GA ČR GAP304/12/0950; GA ČR GA13-08336S; GA MPO FR-TI4/625 Institutional support: RVO:61389013 Keywords : Wilson’s disease * polymer beads * chelators Subject RIV: CA - Inorganic Chemistry Impact factor: 3.350, year: 2014

In Vivo Integrity and Biological Fate of Chelator-Free Zirconium-89-Labeled Mesoporous Silica Nanoparticles.

Science.gov (United States)

Chen, Feng; Goel, Shreya; Valdovinos, Hector F; Luo, Haiming; Hernandez, Reinier; Barnhart, Todd E; Cai, Weibo

2015-08-25

Traditional chelator-based radio-labeled nanoparticles and positron emission tomography (PET) imaging are playing vital roles in the field of nano-oncology. However, their long-term in vivo integrity and potential mismatch of the biodistribution patterns between nanoparticles and radio-isotopes are two major concerns for this approach. Here, we present a chelator-free zirconium-89 ((89)Zr, t1/2 = 78.4 h) labeling of mesoporous silica nanoparticle (MSN) with significantly enhanced in vivo long-term (>20 days) stability. Successful radio-labeling and in vivo stability are demonstrated to be highly dependent on both the concentration and location of deprotonated silanol groups (-Si-O(-)) from two types of silica nanoparticles investigated. This work reports (89)Zr-labeled MSN with a detailed labeling mechanism investigation and long-term stability study. With its attractive radio-stability and the simplicity of chelator-free radio-labeling, (89)Zr-MSN offers a novel, simple, and accurate way for studying the in vivo long-term fate and PET image-guided drug delivery of MSN in the near future.

Kinetics of ion exchange in the chelating resin Dowex A-1

International Nuclear Information System (INIS)

Matsuzuru, Hideo; Wadachi, Yoshiki

1975-01-01

The kinetics of ion exchanges of Ag + , Zn 2+ and Cr 3+ at extremely low concentrations on the chelating resin Dowex A-1 has been studied by means of finite volume method. The rate of exchanges for both Ag + and Zn 2+ is dependent on the ionic strength, particle size of the resin and reaction temperature. At higher ionic strength (0.1 - 0.05) the kinetics is controlled by particle diffusion, whereas at lower ionic one (0.01 - 0.001) film diffusion is predominant. The apparent activation energy obtained is 3.84 kcal/mol for Ag + and 3.91 kcal/mol for Zn 2+ . The exchange rate of Cr 3+ obeys a first-order rate equation independent of the ionic strength and particle size of the resin. The apparent activation energy is 15.5 kcal/mol. These results support the view that the rate-determining step of this reaction is chelate formation reaction. (auth.)

Somatomedin activity before and after chelation therapy in lead-intoxicated children

International Nuclear Information System (INIS)

Rohn, R.D.; Hill, J.R.; Shelton, J.E.

1982-01-01

Somatomedin activity was measured in 21 lead-intoxicated children to determine whether plumbism interferes with the processes of statural (bone) growth. Somatomedin activity was measured both by the rabbit coastal cartilage bioassay and by radioimmunoassay of somatomedin-C. Compared to values in normal children, both the bioassay and radioimmunoassay somatomedin activity was increased. The degree of body lead burden was so extensive that the 21 study children required chelation therapy. Following EDTA or BAL + EDTA chelation therapy, the overall somatomedin activity of these children with plumbism further increased significantly. In contrast, measures of body lead burden--including blood lead levels--decreased after treatment in all lead-intoxicated youngsters. We conclude that plumbism is associated with increased somatomedin activity. Hence the increased somatomedin activity may explain why clinical experience fails to find any long-term deleterious effect of saturnism on statural (bone) growth. Possible mechanisms underlying the increased somatomedin activity in the lead-intoxicated children remain to be defined

Adsorption characteristics of 14C-labeled alanine, aspartic acid and adenosine triphosphate by metal-chelating resins

International Nuclear Information System (INIS)

Ishiyama, Toshio; Matsunami, Tadao; Shibata, Setsuko; Honda, Yoshihide.

1987-01-01

(1) Adsorption properties of 14 C-alanine, 14 C-ATP (adenosine triphosphate) and 14 C-aspartic acid on the metal-chelating resins were determined and found that the Cu(II)-Chelex 100 and Fe(III)-Unicellex UR10, Fe(III)-Chelex 100 chelating resins were highly effective for the adsorption of 14 C-alanine and 14 C-ATP, respectively. (2) Desorption rate of 14 C-ATP from the Fe(III)-Unicellex UR10 and Fe(III)-Chelex 100 resins was somewhat higher than the case of 14 C-alanine, probably because the coordination bonds of Cu-alanine might be stronger than those of Fe-ATP. Thus, 14 C-labeled organic compounds such as 14 C-alanine and 14 C-ATP of a low activity concentration (3.7 mBq/ml) (1 x 10 -7 μCi/ml) in aqueous solution may be measured with liquid scintillation counter after pre-concentration by use of the Fe(III)- and Cu(II)-chelating resin columns. (author)

The interactive effects of chelator, fertilizer, and rhizobacteria for enhancing phytoremediation of heavy metal contaminated soil

Energy Technology Data Exchange (ETDEWEB)

Chen, H.; Cutright, T.J. [Dept. of Civil Engineering, Univ. of Akron, Akron, OH (United States)

2002-07-01

The role of chelator, fertilizer, and enriched rhizobacteria in facilitating Cd, Cr, and Ni accumulation by Helianthus annuus was studied. It was found that by adding a synthetic chelator, EDTA, the shoot concentrations of Cd and Ni were significantly increased from 34.2 mg kg{sup -1} and 14.5 mg kg{sup -1} to 115 mg kg{sup -1} and 117 mg kg{sup -1}, respectively. However, the total biomass of plants was drastically decreased by 50 to 60%. Compared with this treatment, inoculating enriched rhizobacteria to plants grown under similar conditions maintained the surged shoot concentrations of Cd and Ni while increasing the plants biomass by more than 1.6-fold. It was also found that introducing a commercial fertilizer, Hydro-Gro trademark, to plants significantly increased the Ni accumulation by 3-fold and the plant biomass by 1.43-fold. These results suggest that combing fertilizers, chelators and/or rhizobacteria might provide a more effective approach for enhancing phytoremediation. (orig.)

Nitrosothiol Formation and Protection against Fenton Chemistry by Nitric Oxide-induced Dinitrosyliron Complex Formation from Anoxia-initiated Cellular Chelatable Iron Increase*

Science.gov (United States)

Li, Qian; Li, Chuanyu; Mahtani, Harry K.; Du, Jian; Patel, Aashka R.; Lancaster, Jack R.

2014-01-01

Dinitrosyliron complexes (DNIC) have been found in a variety of pathological settings associated with •NO. However, the iron source of cellular DNIC is unknown. Previous studies on this question using prolonged •NO exposure could be misleading due to the movement of intracellular iron among different sources. We here report that brief •NO exposure results in only barely detectable DNIC, but levels increase dramatically after 1–2 h of anoxia. This increase is similar quantitatively and temporally with increases in the chelatable iron, and brief •NO treatment prevents detection of this anoxia-induced increased chelatable iron by deferoxamine. DNIC formation is so rapid that it is limited by the availability of •NO and chelatable iron. We utilize this ability to selectively manipulate cellular chelatable iron levels and provide evidence for two cellular functions of endogenous DNIC formation, protection against anoxia-induced reactive oxygen chemistry from the Fenton reaction and formation by transnitrosation of protein nitrosothiols (RSNO). The levels of RSNO under these high chelatable iron levels are comparable with DNIC levels and suggest that under these conditions, both DNIC and RSNO are the most abundant cellular adducts of •NO. PMID:24891512

Monitoring the progression of calcium and protein solubilisation as affected by calcium chelators during small-scale manufacture of casein-based food matrices.

Science.gov (United States)

McIntyre, Irene; O'Sullivan, Michael; O'Riordan, Dolores

2017-12-15

Calcium and protein solubilisation during small-scale manufacture of semi-solid casein-based food matrices was investigated and found to be very different in the presence or absence of calcium chelating salts. Calcium concentrations in the dispersed phase increased and calcium-ion activity (A Ca ++ ) decreased during manufacture of the matrices containing calcium chelating salts; with ∼23% of total calcium solubilised by the end of manufacture. In the absence of calcium chelating salts, these concentrations were significantly lower at equivalent processing times and remained unchanged as did A Ca ++ , throughout manufacture. The protein content of the dispersed phase was low (≤3% of total protein), but was significantly higher for matrices containing calcium chelating salts. This study elucidates the critical role of calcium chelating salts in modulating casein hydration and dispersion and gives an indication of the levels of soluble calcium and protein required to allow matrix formation during manufacture of casein-based food structures e.g. processed and analogue cheese. Copyright © 2017 Elsevier Ltd. All rights reserved.

Describing and optimizing reversible logic using a functional language

DEFF Research Database (Denmark)

Thomsen, Michael Kirkedal

2012-01-01

the recognisable inversion combinator f^(-1), which defines the inverse function of f using an efficient semantics. It is important to ensure that all circuits descriptions are reversible, and furthermore we must require this to be done statically. This is en- sured by the type system, which also allows...... the description of arbitrary sized circuits. The combination of the functional language and the restricted reversible model results in many arithmetic laws, which provide more possibilities for term rewriting and, thus, the opportunity for good optimisation....

Pulse-reverse electrodeposition for mesoporous metal films: combination of hydrogen evolution assisted deposition and electrochemical dealloying.

Science.gov (United States)

Cherevko, Serhiy; Kulyk, Nadiia; Chung, Chan-Hwa

2012-01-21

Hydrogen evolution assisted electrodeposition is a new bottom-up technique allowing the fast and simple synthesis of nanometals. Electrochemical dealloying is a top-down approach with the same purpose. In this work, we show that a combination of these two methods in sequence by pulse-reverse electrodeposition can be used to prepare high-surface-area nanostructured metals. Highly porous adherent platinum is obtained by the deposition of CuPt alloy during the cathodic cycles and the selective dissolution of copper during the anodic cycles. The convection created by the movement of the hydrogen bubbles increases the deposition rate and removes the dissolved copper ions from the diffusion layer, which ensures the deposition of a film with the same stoichiometry throughout the whole process. Due to the relatively high ratio of copper atoms on the surface in the as-deposited layer, it is proposed that the dealloying kinetics is significantly higher than that usually observed during the dealloying process in a model system. The proposed approach has several advantages over other methods, such as a very high growth rate and needlessness of any post-treatment processes. A detailed analysis of the effect of pulse-reverse waveform parameters on the properties of the films is presented. Mesoporous platinum with pores and ligaments having characteristic sizes of less than 10 nm, an equivalent surface area of up to ca. 220 m(2) cm(-3), and a roughness factor of more than 1000 is fabricated.

Standardization of methodology to derivatization and radiolabeling of the anti-CD20 monoclonal antibody from bifunctional chelator DOTA-NHS-Ester

International Nuclear Information System (INIS)

Massicano, Adriana V.F.; Akanji, Akinkunmi G.; Santos, Josefina S.; Pujatti, Priscilla B.; Couto, Renata M.; Massicano, Felipe; Araujo, Elaine Bortoleti de

2009-01-01

Lymphomas are cancers of the lymphatic system, being the most common the non-Hodgkin lymphoma (NHL). The Radioimmunotherapy (RIT), that increase the cytotoxic effect of monoclonal antibodies (mAb), therefore labeling these Mab with different radioisotopes. RIT combines the specificity of the antibody and the toxicity of the radionuclides. The mAb anti-CD20 is used for treatment of relapse or refractory NHL. The labeling of anti- CD20 with 177 Lu, requires a bifunctional chelating agent that is designed to make a 'connect bridge' between the mAb and the radionuclide. The incorporation of the chelating group in mAb structure is called derivatization. The aim of this work is to study the derivatization of anti-CD20 antibody with DOTA-NHS-ester chelating group and labeling parameters to produce 177 Lu-DOTA-Anti CD20. Five milligrams of anti-CD20 were purified by dialysis against phosphate buffer pH 8.0 and derivatized with DOTA-NHS-ester in 1:250, 1:500 and 1:1000 molar ratios. The reaction was conducted for 1 hour in gently mixing at room temperature and remained under refrigeration for 48 hours. The reaction mixture was purified in gel column Sephadex G-50 ; the aliquots that presented greater protein concentration, were mixed and concentrated. The purified antibody conjugated was added to 111-185MBq (3-5mCi) of 177 LuCl3 diluted in 0.4 M acetate buffer pH 5.5. Radiochemical purity was less than 95% in all the molar ratios, indicating necessity of the purification after the labeling. The mAb derivatized showed stable when stored for to 1 month to 4 deg C and 4 days at -20 deg C. (author)

Chemical-looping combustion in a reverse-flow fixed bed reactor

International Nuclear Information System (INIS)

Han, Lu; Bollas, George M.

2016-01-01

A reverse-flow fixed bed reactor concept for CLC (chemical-looping combustion) is explored. The limitations of conventional fixed bed reactors, as applied to CLC, are overcome by reversing the gas flow direction periodically to enhance the mixing characteristics of the bed, thus improving oxygen carrier utilization and energy efficiency with respect to power generation. The reverse-flow reactor is simulated by a dusty-gas model and compared with an equivalent fixed bed reactor without flow reversal. Dynamic optimization is used to calculate conditions at which each reactor operates at maximum energy efficiency. Several cases studies illustrate the benefits of reverse-flow operation for the CLC with CuO and NiO oxygen carriers and methane and syngas fuels. The results show that periodic reversal of the flow during reduction improves the contact between the fuel and unconverted oxygen carrier, enabling the system to suppress unwanted catalytic reactions and axial temperature and conversion gradients. The operational scheme presented reduces the fluctuations of temperature during oxidation and increases the high-temperature heat produced by the process. CLC in a reverse-flow reactor has the potential to achieve higher energy efficiency than conventional fixed bed CLC reactors, when integrated with a downstream gas turbine of a combined cycle power plant. - Highlights: • Reverse-flow fixed bed CLC reactors for combined cycle power systems. • Dynamic optimization tunes operation of batch and transient CLC systems. • The reverse-flow CLC system provides stable turbine-ready gas stream. • Reverse-flow CLC fixed bed reactor has superior CO 2 capture and thermal efficiency.

Time reversibility, computer simulation, algorithms, chaos

CERN Document Server

Hoover, William Graham

2012-01-01

A small army of physicists, chemists, mathematicians, and engineers has joined forces to attack a classic problem, the "reversibility paradox", with modern tools. This book describes their work from the perspective of computer simulation, emphasizing the author's approach to the problem of understanding the compatibility, and even inevitability, of the irreversible second law of thermodynamics with an underlying time-reversible mechanics. Computer simulation has made it possible to probe reversibility from a variety of directions and "chaos theory" or "nonlinear dynamics" has supplied a useful vocabulary and a set of concepts, which allow a fuller explanation of irreversibility than that available to Boltzmann or to Green, Kubo and Onsager. Clear illustration of concepts is emphasized throughout, and reinforced with a glossary of technical terms from the specialized fields which have been combined here to focus on a common theme. The book begins with a discussion, contrasting the idealized reversibility of ba...

New hydroxypyridinone iron-chelators as potential anti-neurodegenerative drugs.

Science.gov (United States)

Arduino, Daniela; Silva, Daniel; Cardoso, Sandra M; Chaves, Silvia; Oliveira, Catarina R; Santos, M Amelia

2008-05-01

The neuroprotective action of a set of new hydroxypyridinone-based (3,4-HP) compounds (A, B and C), which are iron chelators extra-functionalized with a propargylamino group for potential MAO-B inhibition, was evaluated after cell treatment with MPP+ (an in vivo inducer of parkinsonism) and Abeta(1-40) and/or Abeta(1-42) peptides. Our results show that all these compounds improved cell viability in cells treated with MPP+ and Abeta(1-40) peptide or Abeta(1-42) peptide. In order to evaluate the cellular mechanisms underlying the activity of these compounds, we studied their protective role in caspase activation. All compounds tested were able to prevent MPP+ and Brefeldin A induced caspase-2 activation. They also showed quite effective in the inhibition of caspase-4 and caspase-3 activity, an effector caspase in the apoptotic process. Finally, detection of apoptotic-like cell death after cell exposure to MPP+ was also performed by TUNEL assay. Our results demonstrated that all tested compounds prevented DNA fragmentation by decreasing TUNEL positive cells. A, B and C were more effective than DFP (a 3,4-HP iron-chelating agent in clinical use) in MPP+ induced cell death. Therefore, these results evidenced a neuroprotective and antiapoptotic role for the compounds studied.

Quantum Chemical Investigation on the Antioxidant Activity of Neutral and Anionic Forms of Juglone: Metal Chelation and Its Effect on Radical Scavenging Activity

Directory of Open Access Journals (Sweden)

Aymard Didier Fouegue Tamafo

2017-01-01

Full Text Available The chelation ability of divalent Mg, Ca, Fe, Co, Ni, Cu, Zn, and monovalent Cu ions by neutral and anionic forms of juglone has been investigated at DFT/B3LYP/6-31+G(d,p level of theory in gas and aqueous phases. It is noteworthy that only the 1 : 1 stoichiometry was considered herein. The effects of these metals on the radical scavenging activity of neutral juglone were evaluated via the usual descriptors of hydrogen atom transfer. According to our results, metal chelation by the two forms of juglone was spontaneous and exothermic in both media. Based on the binding energies, Cu(II ion showed the highest affinity for the ligands. QTAIM analyses identified the metal-ligand bonds as intermediate type interactions in all the chelates, except those of Ca and Mg. It was also found that the chelates were better radical scavengers than the ligands. In the gas phase, the scavenging activity of the compounds was found to be governed by direct hydrogen atom transfer, the Co(II chelate being the most reactive. In the aqueous phase also, the sequential proton loss electron transfer was preferred by all the molecules, while the Cu(II chelates were the most reactive.

Synthesis and spectroscopic investigations of hydroxyapatite using a green chelating agent as template

Science.gov (United States)

Gopi, D.; Bhuvaneshwari, N.; Indira, J.; Kavitha, L.

2013-03-01

Hydroxyapatite [Ca10(PO4)6(OH)2, HAP] particles have been successfully synthesized by a cost-effective, eco-friendly green template method using natural and commercially available sucrose as a chelating agent. The sucrose used in this method has been extracted from various sources, three from natural and one from commercially available sources are exploited in our study to achieve a controlled crystallinity, particle size as well as uniform morphology. Spectral characterizations involving Fourier transform infrared spectroscopy (FT-IR) for the functional group analysis of sucrose and HAP; carbon-13 nuclear magnetic resonance spectroscopy (13C NMR) for the identification of the carbon atoms in sucrose and in HAP; liquid chromatography/mass spectrometry (LC-MS) for the determination of the hydrolyzed products of sucrose; and X-ray diffraction (XRD) techniques for the phase identification of the HAP particles were performed. The morphology of the HAP particles were assessed thoroughly using a scanning electron microscope (SEM) equipped with energy dispersive X-ray analysis (EDAX). The experimental results indicate that the obtained HAP using the natural sucrose as a chelating agent is of phase pure, with a well defined morphology having discrete particles without any agglomeration than the HAP from commercially available sucrose. Further, the reduced particle size can be achieved from the stem sugarcane extract as the source of the chelating agent.

Synthesis and spectroscopic investigations of hydroxyapatite using a green chelating agent as template.

Science.gov (United States)

Gopi, D; Bhuvaneshwari, N; Indira, J; Kavitha, L

2013-03-01

Hydroxyapatite [Ca(10)(PO(4))(6)(OH)(2), HAP] particles have been successfully synthesized by a cost-effective, eco-friendly green template method using natural and commercially available sucrose as a chelating agent. The sucrose used in this method has been extracted from various sources, three from natural and one from commercially available sources are exploited in our study to achieve a controlled crystallinity, particle size as well as uniform morphology. Spectral characterizations involving Fourier transform infrared spectroscopy (FT-IR) for the functional group analysis of sucrose and HAP; carbon-13 nuclear magnetic resonance spectroscopy ((13)C NMR) for the identification of the carbon atoms in sucrose and in HAP; liquid chromatography/mass spectrometry (LC-MS) for the determination of the hydrolyzed products of sucrose; and X-ray diffraction (XRD) techniques for the phase identification of the HAP particles were performed. The morphology of the HAP particles were assessed thoroughly using a scanning electron microscope (SEM) equipped with energy dispersive X-ray analysis (EDAX). The experimental results indicate that the obtained HAP using the natural sucrose as a chelating agent is of phase pure, with a well defined morphology having discrete particles without any agglomeration than the HAP from commercially available sucrose. Further, the reduced particle size can be achieved from the stem sugarcane extract as the source of the chelating agent. Copyright © 2012 Elsevier B.V. All rights reserved.

Protection against SR 4233 (tirapazamine) aerobic cytotoxicity by the metal chelators desferrioxamine and tiron

International Nuclear Information System (INIS)

Herscher, L.L.; Krishna, M.C.; Cook, J.A.

1994-01-01

Metal chelating agents and antioxidants were evaluated as potential protectors against aerobic SR 4233 cytotoxicity in Chinese hamster V79 cells. The differential protection of aerobic and hypoxic cells by two metal chelators, desferrrioxamine and Tiron, is discussed in the context of their potential use in the on-going clinical trials with SR 4233. Cytotoxicity was evaluated using clonogenic assay. SR 4233 exposure was done in glass flasks as a function of time either alone or in the presence of the following agents: superoxide dismutase, catalase, 5,5-dimethyl-1-pyrroline, Trolox, ICRF-187, desferrioxamine, Tiron (1,2-dihydroxybenzene-3,5-disulfonate), and ascorbic acid. Experiments done under hypoxic conditions were carried out in specially designed glass flasks that were gassed with humidified nitrogen/carbon dioxide mixture and with a side-arm reservoir from which SR 4233 was added to cell media after hypoxia was obtained. Electron paramagnetic resonance studies were also performed. Electron paramagnetic resonance and spectrophotometry experiments suggest that under aerobic conditions SR 4233 undergoes futile redox cycling to produce superoxide. Treatment of cells during aerobic exposure to SR 4233 with the enzymes superoxide dismutase and catalase, the spin trapping agent DMPO, the water-soluble vitamin E analog Trolox, and the metal chelator ICRF-187 provided little or no protection against aerobic SR 4233 cytotoxicity. However, two other metal chelators, desferrioxamine and Tiron afforded significant protection against minimal protection to hypoxic cells treated with SR 4233. One potential mechanism of aerobic cytotoxicity is redox cycling of SR 4233 with molecular oxygen resulting in several potentially toxic oxidative species that overburden the intrinsic intracellular detoxification systems such as superoxide dismutase, catalase, and glutathione peroxidase. 23 refs., 4 figs., 1 tab

Synthesis, spectroscopic studies and antimicrobial activity of chelates 2-(acetyloxy)-benzoic acid with transition metals (CR+3, MN+2, NI+2 AND CU+2)

International Nuclear Information System (INIS)

Khan, B.; Mateen, B.; Ahmed, F.; Ahmed, F.

2007-01-01

2-(acetyloxy)-Benzoic acid chelates with Cr+3, Mn+2, Ni+2 and Cu+2 were synthesized and characterized by the melting point, solubility, Fourier Transform Infrared (FT-IR) Spectroscopy, Atomic Absorption Spectroscopy (AAS), X-Ray Diffraction (XRD) method and evaluated by antimicrobial activity. The functional group present in the chelates was determined by Fourier Transform Infrared Spectroscopy, by X-Ray Diffraction analysis crystal data of chelates, their inter-atomic and inter-planer spacing was also determined. The amount of metal in the chelates was estimated by Atomic Absorption Spectroscopy and their Antimicrobial Activity was studied against Pseudomonas aeruginosa, Escherisha coli and Staphylococcus aureus. (author)

A Zinc Chelator TPEN Attenuates Airway Hyperresponsiveness Airway Inflammation in Mice In Vivo

Directory of Open Access Journals (Sweden)

Satoru Fukuyama

2011-01-01

Conclusions: In pulmonary allergic inflammation induced in mice immunized with antigen without alum, zinc chelator inhibits airway inflammation and hyperresponsiveness. These findings suggest that zinc may be a therapeutic target of allergic asthma.

TEM and SEM observation of uranium induced renal necrosis and the result of chelates treatment on rats

International Nuclear Information System (INIS)

Sun Shiquan; Li Baoxing; Lai Chixiang; You Zhanyun

1987-01-01

The TEM (transmission electron microscope) and SEM (scanning electron microscope) observation of uranium induced renal necrosis and the result of chelates treatment on rats are reported. Ultrastructural changes in kidney related with the impairment of intracellular fluid transportation can be found after acute uranium intoxication in rats, such as: condensation and swelling of mitochondria, matrix edema, dilatation of intercellular space, disappearance of basal folds, thickening of basal web, intensification of basal lamina of the proximal convoluted tubule epithelium cells, and foot processes swelling, diminishing of endothelium fenestrae of the renal glomerulus. Heavy metal chelates DTPA and H-73-10 treatment may result in intracellular fluid accumulation and condensed grannule formation in lysosome. Treatment with these chelates in the critical stage of uranium intoxication may accelerate the necrosis instead of diminishing. This may be related to the augment of the load of lysosome and intracellular system of fluid transportation

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

Energy Technology Data Exchange (ETDEWEB)

Orcutt, Kelly Davis; Slusarczyk, Adrian L. [Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Cieslewicz, Maryelise [Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Ruiz-Yi, Benjamin [Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Bhushan, Kumar R. [Division of Hematology/Oncology, Beth Israel Deaconess Medical Center, Boston, MA 02215 (United States); Frangioni, John V. [Division of Hematology/Oncology, Beth Israel Deaconess Medical Center, Boston, MA 02215 (United States); Department of Radiology, Beth Israel Deaconess Medical Center, Boston, MA 02215 (United States); Wittrup, K. Dane, E-mail: wittrup@mit.ed [Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)

2011-02-15

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 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (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 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 pM is needed for near-maximal hapten retention. We affinity matured 2D12.5 with an initial binding constant of about 10 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, pretargeted high-affinity scFv results in significantly higher tumor retention of a {sup 111}In-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.

IR, UV-Vis, magnetic and thermal characterization of chelates of some catecholamines and 4-aminoantipyrine with Fe(III) and Cu(II)

Science.gov (United States)

Mohamed, Gehad G.; Zayed, M. A.; El-Dien, F. A. Nour; El-Nahas, Reham G.

2004-07-01

The dopamine derivatives participate in the regulation of wide variety of physiological functions in the human body and in medication life. Increase and/or decrease in the concentration of dopamine in human body reflect an indication for diseases such as Schizophrenia and/or Parkinson diseases. α-Methyldopa (α-MD) in tablets is used in medication of hypertension. The Fe(III) and Cu(II) chelates with coupled products of adrenaline hydrogen tartarate (AHT), levodopa (LD), α-MD and carbidopa (CD) with 4-aminoantipyrine (4-AAP) are prepared and characterized. Different physico-chemical methods like IR, magnetic and UV-Vis spectra are used to investigate the structure of these chelates. Fe(III) form 1:2 (M:catecholamines) chelates while Cu(II) form 1:1 chelates. Catecholamines behave as a bidentate mono- or dibasic ligands in binding to the metal ions. IR spectra show that the catecholamines are coordinated to the metal ions in a bidentate manner with O,O donor sites of the phenolic - OH. Magnetic moment measurements reveal the presence of Fe(III) chelates in octahedral geometry while the Cu(II) chelates are square planar. The thermal decomposition of Fe(III) and Cu(II) complexes is studied using thermogravimetric (TGA) and differential thermal analysis (DTA) techniques. The water molecules are removed in the first step followed immediately by decomposition of the ligand molecules. The activation thermodynamic parameters, such as, energy of activation, enthalpy, entropy and free energy change of the complexes are evaluated and the relative thermal stability of the complexes are discussed.

Assessment of the body burden of chelatable lead: a model and its application to lead workers.

OpenAIRE

Araki, S; Ushio, K

1982-01-01

A hypothetical model was introduced to estimate the body burden of chelatable lead from the mobilisation yield of lead by calcium disodium ethylenediamine tetra-acetate (CaEDTA). It was estimated that, on average, 14 and 19% of the body burden was mobilised into the urine during the 24 hours after an injection of 53.4 mumol (20 mg) and 107 mumol (40 mg) CaEDTA per kg bodyweight, respectively. The body burden of chelatable lead ranged from 4 mumol (0.8 mg) to 120 mumol (24.9 mg) (mean 37 mumol...

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

International Nuclear Information System (INIS)

Taki, Tomohiro

2000-12-01

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

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

Science.gov (United States)

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.

The Correction of a Secondary Bilateral Cleft Lip Nasal Deformity Using Refined Open Rhinoplasty with Reverse-U Incision, V-Y Plasty, and Selective Combination with Composite Grafting: Long-term Results

Directory of Open Access Journals (Sweden)

Byung Chae Cho

2012-05-01

Full Text Available Background This article presents long-term outcomes after correcting secondary bilateralcleft lip nasal deformities using a refined reverse-U incision and V-Y plasty or in combinationwith a composite graft in order to elongate the short columella.Methods A total of forty-six patients underwent surgery between September 1996 andDecember 2008. The age of the patients ranged from 3 to 19 years of age. A bilateral reverse-Uincision and V-Y plasty were used in 24 patients. A composite graft from the helical rootwas combined with a bilateral reverse-U incision in the 22 patients who possessed a severelyshortened columella. The follow-up period ranged between 2 and 10 years.Results A total of 32 patients out of 46 were evaluated postoperatively. The average columellalength was significantly improved from an average of 3.7 mm preoperatively to 8.5 mmpostoperatively. The average ratio of the columella height to the alar base width was 0.18preoperatively and 0.29 postoperatively. The postoperative basal and lateral views revealed abetter shape of the nostrils and columella. The elongated columella, combined with a compositegraft, presented good maintenance of the corrected position with no growth disturbance. Acomposite graft showed color mismatching in several patients. Twenty-six patients demonstratedno alar-columella web deformity and satisfactory symmetry of the nostrils. Four patientsexperienced a drooping and overhanging of the corrected alar-columella web.Conclusions A bilateral reverse-U incision with V-Y plasty or in combination with acomposite graft was effective in correcting secondary bilateral cleft lip nasal deformity.

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

Science.gov (United States)

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

Synthesis, characterization and ion- exchange study of poly[(2,4-dihydroxy benzophenone)butylene] resin and its poly chelates with transition metals

International Nuclear Information System (INIS)

Joshi, J. D.; Patel, N.B.; Patel, S. D.

2006-01-01

The polymeric ligand poly[(2,4-dihydroxy benzophenone)butylene] H(DHBP-BD) forms 1 :2 metal-ligand complexes with Ni(ll), Co(ll), Cu(ll) and Zn(ll). The polymeric ligand and its poly chelates were characterized on the basis of elemental analyses, magnetic susceptibilities, IR-spectroscopy, UV-visible spectra, NMR, thermogravimetric analyses. The molecular weight of resin was determined using number average molecular weight (M n ) by vapour pressure osmometry method. The stereochemistry in case of the Cu(ll) poly chelate is square-planar, tetrahedral for Zn(ll) and octahedral for Ni(ll) and Co(ll). The stereochemistry in each chelate is proposed on the basis of magnetic susceptibilities and electronic spectra. The IR spectra show that the bidentate ligand coordinates through the oxygen atom of the carbonyl and phenolic group with replacement of hydrogen by metal ions, respectively. All the chelates are paramagnetic in nature except the Zn(ll) chelate which is diamagnetic. The ion-exchange study of the prepared resin was checked by batch equilibration method with selected metal ions [Cu(ll), Ni(ll), Fe(lll) and UO 2 2+( VI)] at varying electrolyte concentration, pH and time. It is found that, resin can be used as an ion-exchanger

Nitrosothiol formation and protection against Fenton chemistry by nitric oxide-induced dinitrosyliron complex formation from anoxia-initiated cellular chelatable iron increase.

Science.gov (United States)

Li, Qian; Li, Chuanyu; Mahtani, Harry K; Du, Jian; Patel, Aashka R; Lancaster, Jack R

2014-07-18

Dinitrosyliron complexes (DNIC) have been found in a variety of pathological settings associated with (•)NO. However, the iron source of cellular DNIC is unknown. Previous studies on this question using prolonged (•)NO exposure could be misleading due to the movement of intracellular iron among different sources. We here report that brief (•)NO exposure results in only barely detectable DNIC, but levels increase dramatically after 1-2 h of anoxia. This increase is similar quantitatively and temporally with increases in the chelatable iron, and brief (•)NO treatment prevents detection of this anoxia-induced increased chelatable iron by deferoxamine. DNIC formation is so rapid that it is limited by the availability of (•)NO and chelatable iron. We utilize this ability to selectively manipulate cellular chelatable iron levels and provide evidence for two cellular functions of endogenous DNIC formation, protection against anoxia-induced reactive oxygen chemistry from the Fenton reaction and formation by transnitrosation of protein nitrosothiols (RSNO). The levels of RSNO under these high chelatable iron levels are comparable with DNIC levels and suggest that under these conditions, both DNIC and RSNO are the most abundant cellular adducts of (•)NO. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

Polyaminoquinoline iron chelators for vectorization of antiproliferative agents: design, synthesis, and validation.

Science.gov (United States)

Corcé, Vincent; Morin, Emmanuelle; Guihéneuf, Solène; Renault, Eric; Renaud, Stéphanie; Cannie, Isabelle; Tripier, Raphaël; Lima, Luís M P; Julienne, Karine; Gouin, Sébastien G; Loréal, Olivier; Deniaud, David; Gaboriau, François

2012-09-19

Iron chelation in tumoral cells has been reported as potentially useful during antitumoral treatment. Our aim was to develop new polyaminoquinoline iron chelators targeting tumoral cells. For this purpose, we designed, synthesized, and evaluated the biological activity of a new generation of iron chelators, which we named Quilamines, based on an 8-hydroxyquinoline (8-HQ) scaffold linked to linear polyamine vectors. These were designed to target tumor cells expressing an overactive polyamine transport system (PTS). A set of Quilamines bearing variable polyamine chains was designed and assessed for their ability to interact with iron. Quilamines were also screened for their cytostatic/cytotoxic effects and their selective uptake by the PTS in the CHO cell line. Our results show that both the 8-HQ moiety and the polyamine part participate in the iron coordination. HQ1-44, the most promising Quilamine identified, presents a homospermidine moiety and was shown to be highly taken up by the PTS and to display an efficient antiproliferative activity that occurred in the micromolar range. In addition, cytotoxicity was only observed at concentrations higher than 100 μM. We also demonstrated the high complexation capacity of HQ1-44 with iron while much weaker complexes were formed with other cations, indicative of a high selectivity. We applied the density functional theory to study the binding energy and the electronic structure of prototypical iron(III)-Quilamine complexes. On the basis of these calculations, Quilamine HQ1-44 is a strong tridentate ligand for iron(III) especially in the form of a 1:2 complex.

Effects of synthetic Zn chelates on flax response and soil Zn status

Energy Technology Data Exchange (ETDEWEB)

Gonzalez, D.; Almendros, P.; Alvarez, J.M.

2016-11-01

Throughout the world, flax (Linum usitatissimum L.) is often grown in Zn-deficient soils, but appropriate fertilizer management can optimize both crop yield and micronutrient content. A greenhouse experiment was conducted on Typic Haploxeralf (pH 6.1) and Typic Calcixerept (pH 8.1) soils to study the relative efficiency of chelated Zn using two application rates of three different Zn sources [Zn-EDDHSA, ethylenediamine-di-(2-hydroxy-5-sulfophenylacetate of Zn); Zn-HEDTA, N-2-hydroxyethyl-ethylenediaminetriacetate of Zn; and Zn-EDTA, ethylenediaminetetraacetate of Zn]. Dry matter /DM) yield, Zn concentration, chlorophyll content, crude fiber and tensile properties were monitored and the soil-Zn status (available-Zn, Zn-fractions and total-Zn) was assessed. Zinc chelate applications increased the most labile forms of Zn in soils and Zn concentrations in plants. The low rate of Zn generally had a beneficial effect on DM yield and tensile properties. The exception was Zn-EDTA in the weakly acidic soil, where the highest Zn concentrations were observed in leaves and whole shoots; this coincided with the largest concentrations of labile Zn in soil. The most efficient fertilizers were Zn-EDDHSA (in both soils) and Zn-EDTA (in the calcareous soil). The relatively large amounts of labile and available Zn present in both of the soils fertilized with Zn-EDTA points to the applying this chelate at lower rate than 5 mg Zn/kg; this should, in turn, reduce the cost of Zn fertilization and minimize environmental pollution risk. (Author)

A bis(3-hydroxy-4-pyridinone)-EDTA derivative as a strong chelator for M3+ hard metal ions: complexation ability and selectivity.

Science.gov (United States)

Gama, Sofia; Dron, Paul; Chaves, Silvia; Farkas, Etelka; Santos, M Amélia

2009-08-21

The study of chelating compounds is very important to solve problems related to human metal overload. 3-Hydroxy-3-pyridinones (HP), namely deferiprone, have been clinically used for chelating therapy of Fe and Al over the last decade. A multi-disciplinary search for alternative molecules led us to develop poly-(3-hydroxy-4-pyridinones) to increase metal chelation efficacy. We present herein a complexation study of a new bis-(3-hydroxy-4-pyridinone)-EDTA derivative with a set of M(3+) hard metal ions (M = Fe, Al, Ga), as well as Zn(2+), a biologically relevant metal ion. Thus a systematic aqueous solution equilibrium study was performed using potentiometric and spectroscopic techniques (UV-Vis, NMR methods). These set of results enables the establishment of specific models as well as the determination of thermodynamic stability constants and coordination modes of the metal complexes. The results indicate that this ligand has a higher affinity for chelating to these hard metal ions than deferiprone, and that the coordination occurs mostly through the HP moieties. Furthermore, it was also found that this ligand has a higher selectivity for chelating to M(3+) hard metal ions (M = Fe, Al, Ga) than Zn(2+).

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

Science.gov (United States)

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.

Switch from antagonist to agonist after addition of a DOTA chelator to a somatostatin analog

International Nuclear Information System (INIS)

Reubi, Jean Claude; Cescato, Renzo; Waser, Beatrice; Erchegyi, Judit; Rivier, Jean E.

2010-01-01

Peptide receptor targeting has become an increasingly attractive method to target tumors diagnostically and radiotherapeutically. Peptides linked to a variety of chelators have been developed for this purpose. They have, however, rarely been tested for their agonistic or antagonistic properties. We report here on a somatostatin antagonist that switched to an agonist upon coupling to a DOTA chelator. Two novel somatostatin analogs, 406-040-15 and its DOTA-coupled counterpart 406-051-20, with and without cold Indium labeling, were tested for their somatostatin receptor subtypes 1-5 (sst 1 -sst 5 ) binding affinity using receptor autoradiography. Moreover, they were tested functionally for their ability to affect sst 2 and sst 3 internalization in vitro in HEK293 cells stably expressing the human sst 2 or sst 3 receptor, using an immunofluorescence microscopy-based internalization assay. All three compounds were characterized as pan-somatostatin analogs having a high affinity for all five sst. In the sst 2 internalization assay, all three compounds showed an identical behavior, namely, a weak agonistic effect complemented by a weak antagonistic effect, compatible with the behavior of a partial agonist. Conversely, in the sst 3 internalization assay, 406-040-15 was a full antagonist whereas its DOTA-coupled counterpart, 406-051-20, with and without Indium labeling, switched to a full agonist. Adding the DOTA chelator to the somatostatin analog 406-040-15 triggers a switch at sst 3 receptor from an antagonist to an agonist. This indicates that potential radioligands for tumor targeting should always be tested functionally before further development, in particular if a chelator is added. (orig.)

Aryl Insertion vs Aryl-Aryl Coupling in C,C-Chelated Organoborates: The "Missing Link" of Tetraarylborate Photochemistry.

Science.gov (United States)

Radtke, Julian; Mellerup, Soren K; Bolte, Michael; Lerner, Hans-Wolfram; Wang, Suning; Wagner, Matthias

2018-06-14

The photoreactivity of 9-borafluorene-based, C,C-chelated organoborates was investigated. Unlike the related tetraarylborates, the charge-transfer transitions imparted by the biphenyl chelate lead to selective insertion of one aryl substituent into the endocyclic B-C bond of the 9-borafluorene moiety, resulting in the formation of boratanorcaradienes. This photoreaction likely proceeds according to a Zimmerman rearrangement, which is analogous to one of the initially proposed mechanisms for tetraarylborates and provides additional insight into these long-debated photochemical reactions.

From chelating precursors to La0.05Sr0.95CoO3-y oxide

International Nuclear Information System (INIS)

Hong, L.; Guo, F.; Lin, J.

1999-01-01

Several La 0.05 Sr 0.95 CoO 3-y (LSCO-95) powders were synthesized by means of a chelated complex-based precursor approach, which involved pyrolysis of chelating precursors and subsequent calcination of the resulting oxides. This paper focuses on the coordination effects of the precursors on the formation of the crystalline phases of the LSCO-95 oxide, showing that when the precursor is composed of EDTA-metal complexes, the perovskite-type oxide LSCO-95, an electronic-ionic mixed conducting ceramic material, can be achieved. In contrast, those LSCO-95 powders obtained initially from the pyrolysis of the precursors containing other coordination ligands possess only the undesirable hexagonal structure

Evaluation of butorphanol, medetomidine and midazolam as a reversible narcotic combination in free-ranging African lions (Panthera leo).

Science.gov (United States)

Wenger, Sandra; Buss, Peter; Joubert, Jenny; Steenkamp, Johan; Shikwambana, Purvance; Hatt, Jean-Michel

2010-11-01

To evaluate the effects of the combination butorphanol, medetomidine and midazolam (BMM) and its reversibility in lions. Prospective clinical trial. Thirty free-ranging lions, 10 male and 20 female, weighing 81-210 kg. Lions were immobilised with butorphanol mean 0.31 ± SD 0.034 mg kg(-1), medetomidine 0.052 ± 0.006 mg kg(-1), midazolam 0.21 ± 0.024 mg kg(-1) and hyaluronidase 1250 IU administered intramuscularly with a dart gun. Upon recumbency, physiological parameters and anaesthetic depth were monitored 10-15 minutes after darting (T1) and repeated every 10 minutes for a further 30 minutes (T2, T3, T4). Arterial blood gas analyses were performed at T1 and T4. At the end of the procedure, 45-60 minutes after initial darting, immobilisation was reversed with naltrexone 0.68 ± 0.082 mg kg(-1), atipamezole 0.26 ± 0.031 mg kg(-1), and flumazenil 0.0032 ± 0.0007 mg kg(-1) administered intravenously and subcutaneously. The BMM combination rapidly induced immobilisation and lateral recumbency was reached within 7.25 ± 2.3 minutes. Median induction score [scored 1 (excellent) to 4 (poor)] was 1.4 (range 1-2). Cardio-respiratory parameters were stable. Heart rate varied from 32 to 72 beats per minute, respiratory rate from 14 to 32 breaths minute(-1) and rectal temperature from 36.6 to 40.3 °C. No sudden arousals were observed. Arterial blood gas analyses revealed a mean pH of 7.33, PaCO(2) of 33 mmHg and PaO(2) of 87 mmHg. Mild to moderate hypoxemia was seen in four lions. Recovery was smooth and lions were walking within 4.4 ± 4.25 minutes. Median recovery score [scored 1 (excellent) to 4 (poor)] was 1.3 (range 1-2). The drug combination proved to be effective in immobilising free-ranging healthy lions of both sexes with minimal cardio-respiratory changes. © 2010 The Authors. Veterinary Anaesthesia and Analgesia © 2010 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesiologists.

Reducing the potential for migration of radioactive waste: Aqueous thermal degradation of the chelating agent disodium EDTA

International Nuclear Information System (INIS)

Boles, J.S.; Ritchie, K.; Crerar, D.A.

1987-01-01

Ethylenediaminetetraacetic acid (EDTA), a common component of cleaning solutions used for decontamination of radioactive equipment, has been associated with increased migration of radionuclides into local groundwaters at some radwaste disposal sites. It has been proposed that predisposal thermal degradation of EDTA-containing aqueous solutions may reduce the potential for chelate-enhanced mobilization of radionuclides at these sites. Aqueous thermal degradation experiments with disodium EDTA have shown that the compound degrades rapidly at 200 0 C with an activation energy of 114.3 +- 7.87 kJ/mol, and forms the decomposition product methyliminodiacetic acid (MIDA). A comparison of the values for stability constants of transition metal and actinide complexes with EDTA, MIDA, and two other reported degradation products, indicates that the chelating efficiency of the degradation products is 6 to 22 orders of magnitude lower than that of EDTA at 25 0 C. It is concluded that aqueous thermal degradation should significantly reduce the overall chelating efficiency of EDTA-containing solutions

The in-capillary DPPH-capillary electrophoresis-the diode array detector combined with reversed-electrode polarity stacking mode for screening and quantifying major antioxidants in Cuscuta chinensis Lam.

Science.gov (United States)

Liu, Jiao; Tian, Ji; Li, Jin; Azietaku, John Teye; Zhang, Bo-Li; Gao, Xiu-Mei; Chang, Yan-Xu

2016-07-01

An in-capillary 2, 2-diphenyl-1-picrylhydrazyl (DPPH)-CE-the DAD (in-capillary DPPH-CE-DAD) combined with reversed-electrode polarity stacking mode has been developed to screen and quantify the active antioxidant components of Cuscuta chinensis Lam. The operation parameters were optimized with regard to the pH and concentration of buffer solution, SDS, β-CDs, organic modifier, as well as separation voltage and temperature. Six antioxidants including chlorogenic acid, p-coumaric acid, rutin, hyperin, isoquercitrin, and astragalin were screened and the total antioxidant activity of the complex matrix was successfully evaluated based on the decreased peak area of DPPH by the established DPPH-CE-DAD method. Sensitivity was enhanced under reversed-electrode polarity stacking mode and 10- to 31-fold of magnitude improvement in detection sensitivity for each analyte was attained. The results demonstrated that the newly established in-capillary DPPH-CE-DAD method combined with reversed-electrode polarity stacking mode could integrate sample concentration, the oxidizing reaction, separation, and detection into one capillary to fully automate the system. It was considered a suitable technique for the separation, screening, and determination of trace antioxidants in natural products. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Curcumin protects nigral dopaminergic neurons by iron-chelation in the 6-hydroxydopamine rat model of Parkinson's disease

Institute of Scientific and Technical Information of China (English)

Xi-Xun Du; Hua-Min Xu; Hong Jiang; Ning Song; Jun Wang; Jun-Xia Xie

2012-01-01

[Objective] Curcumin is a plant polyphenolic compound and a major component of spice turmeric (Curcuma longa).It has been reported to possess free radical-scavenging,iron-chelating,and anti-inflammatory properties in different tissues.Our previous study showed that curcumin protects MES23.5 dopaminergic cells from 6-hydroxydopamine (6-OHDA)-induced neurotoxicity in vitro.The present study aimed to explore this neuroprotective effect in the 6-OHDAlesioned rat model of Parkinson's disease in vivo.[Methods] Rats were given intragastric curcumin for 24 days.6-OHDA lesioning was conducted on day 4 of curcumin treatment.Dopamine content was assessed by high-performance liquid chromatography with electrochemical detection,tyrosine hydroxylase (TH)-containing neurons by immunohistochemistry,and iron-containing cells by Perls' iron staining.[Results] The dopamine content in the striatum and the number of THimmunoreactive neurons decreased after 6-OHDA treatment.Curcumin pretreatment reversed these changes.Further studies demonstrated that 6-OHDA treatment increased the number of iron-staining cells,which was dramatically decreased by curcumin pretreatment.[Conclusion]The protective effects of curcumin against 6-OHDA may be attributable to the ironchelating activity of curcumin to suppress the iron-induced degeneration of nigral dopaminergic neurons.

Solar Desalination System Model for Sizing of Photovoltaic Reverse Osmosis (PVRO)

KAUST Repository

Habib, Abdulelah; Zamani, Vahraz; Kleissl, Jan

2015-01-01

loads, are considered as an ON/OFF units to track these solar energy variations. Reverse osmosis units are different in sizes and numbers. Various combinations of reverse osmosis units in size and capacity provide different water desalination system

Jacks of metal(loid chelation trade in plants – an overview

Directory of Open Access Journals (Sweden)

Naser A. Anjum

2015-04-01

Full Text Available Varied environmental compartments including soils are being contaminated by a myriad toxic metal(loids (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 glutathione (GSH (reduced GSH; phytochelatins, PCs; metallothioneins, MTs and non-GSH (histidine, nicotianamine, organic acids origin. This paper presents an appraisal of recent reports on both GSH and non-GSH associated compounds in an effort to shed light on the significance of these compounds in metal-plant tolerance, as well as to provide scientific clues for the development of phytoextraction strategies.

Influence of direct and alternating current electric fields on efficiency promotion and leaching risk alleviation of chelator assisted phytoremediation.

Science.gov (United States)

Luo, Jie; Cai, Limei; Qi, Shihua; Wu, Jian; Sophie Gu, Xiaowen

2018-03-01

Direct and alternating current electric fields with various voltages were used to improve the decontamination efficiency of chelator assisted phytoremediation for multi-metal polluted soil. The alleviation effect of electric field on leaching risk caused by chelator application during phytoremediation process was also evaluated. Biomass yield, pollutant uptake and metal leaching retardation under alternating current (AC) and direct current (DC) electric fields were compared. The biomass yield of Eucalyptus globulus under AC fields with various voltages (2, 4 and 10 V) were 3.91, 4.16 and 3.67kg, respectively, significantly higher than the chelator treatment without electric field (2.71kg). Besides growth stimulation, AC fields increased the metal concentrations of plant tissues especially in aerial parts manifested by the raised translocation factor of different metals. Direct current electric fields with low and moderate voltages increased the biomass production of the species to 3.45 and 3.12kg, respectively, while high voltage on the contrary suppressed the growth of the plants (2.66kg). Under DC fields, metal concentrations elevated obviously with increasing voltages and the metal translocation factors were similar under all voltages. Metal extraction per plant achieved the maximum value under moderate voltage due to the greatest biomass production. DC field with high voltage (10V) decreased the volume of leachate from the chelator treatment without electric field from 1224 to 56mL, while the leachate gathered from AC field treatments raised from 512 to 670mL. DC field can retard the downward movement of metals caused by chelator application more effectively relative to AC field due to the constant water flow and electroosmosis direction. Alternating current field had more promotive effect on chelator assisted phytoremediation efficiency than DC field illustrated by more metal accumulation in the species. However, with the consideration of leaching risk, DC

A new method to describe two-phase solvent extraction based on net transport potential derived as linear combinations of forward and reverse constituents

International Nuclear Information System (INIS)

Nabeshima, Masahiro

1998-01-01

With the view to avoiding the difficulties encountered in estimating thermodynamic activities of the multiple chemical species in two-phase liquid system, a set of forward, reverse, net and total transport potentials are defined to represent the chemical state of a transferring solute during transient using bulk concentrations. The net transport potential corresponds to that in the conventional two-film model of diffusion-controlled processes. The overall driving forces of mass transport are redefined as the derivatives of the relevant transport potentials differentiated with respect to a state variable newly defined in terms of the bulk concentrations of the solute contained in both phases. Net and total quantities, i.e. transport potentials, overall driving forces and the molar fluxes are obtained as linear combinations of those for forward and reverse directions. The topical features presented by these quantities and their mutual relations are discussed in detail. The experimental new overall transport coefficient for U(VI) varied in accord with the changes in the theoretical net transport potential and overall driving force. The present method permits describing the extractive mass transport consistently both to forward and reverse directions of transport. (author)

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

Science.gov (United States)

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.

Zinc chelates as new activators for sulphur vulcanization of acrylonitrile-butadiene elastomer

Directory of Open Access Journals (Sweden)

2009-04-01

Full Text Available The goal of this work was to apply several zinc chelates as activators for sulphur vulcanization of acrylonitrilebutadiene elastomer (NBR, in order to find alternatives for the conventionally used zinc oxide. In this article, we discuss the effects of different zinc complexes on the cure characteristics, crosslinks distribution in the elastomer network and mechanical properties of acrylonitrile-butadiene rubber. Zinc chelates seem to be good substitutes for zinc oxide as activators for sulphur vulcanization of NBR rubber, without detrimental effects on the crosslinking process and physical properties of the obtained vulcanizates. Moreover, application of zinc complexes allows to reduce the amount of zinc ions in rubber compounds by 40% compared to conventionally crosslinked vulcanizates with zinc oxide. It is a very important ecological goal since zinc oxide is classified as toxic to aquatic species and its amount in rubber products must be reduced below 2.5% at least. From a technological point of view it is a very important challenge.

Determination of cadmium in seawater by chelate vapor generation atomic fluorescence spectrometry

Science.gov (United States)

Sun, Rui; Ma, Guopeng; Duan, Xuchuan; Sun, Jinsheng

2018-03-01

A method for the determination of cadmium in seawater by chelate vapor generation (Che-VG) atomic fluorescence spectrometry is described. Several commercially available chelating agents, including ammonium pyrrolidine dithiocarbamate (APDC), sodium dimethyl dithiocarbamate (DMDTC), ammonium dibutyl dithiophosphate (DBDTP) and sodium O,O-diethyl dithiophosphate (DEDTP), are compared with sodium diethyldithiocarbamate (DDTC) for the Che-VG of cadmium, and results showed that DDTC and DEDTP had very good cadmium signal intensity. The effect of the conditions of Che-VG with DDTC on the intensity of cadmium signal was investigated. Under the optimal conditions, 85 ± 3% Che-VG efficiency is obtained for cadmium. The detection limit (3σ) obtained in the optimal conditions was 0.19 ng ml- 1. The relative standard deviation (RSD, %) for ten replicate determinations at 2 ng ml- 1 Cd was 3.42%. The proposed method was successfully applied to the ultratrace determination of cadmium in seawater samples by the standard addition method.

Experimental lead intoxication in dogs: a comparison of blood lead and urinary delta-aminolevulinic acid following intoxication and chelation therapy.

Science.gov (United States)

Green, R A; Selby, L A; Zumwalt, R W

1978-01-01

Intravenous lead administration to dogs produced an acute syndrome of lead intoxication charcterized by depression, vomiting, anorexia and weight loss. The effect of chelation therapy with calcium disodium ethylene diamine tetraacetate, penicillamine or both was determined by serially monitoring changes in blood lead and urine delta-aminolevulinic acid. Following therapy, blood lead values were significantly lower in chelated dogs than non-treated lead exposed dogs on days 7 and 10. Urine delta-aminolevulinic acid at day 7 was significantly higher in untreated lead exposed dogs than in other groups. There was no significant difference in blood lead or urine delta-aminolevulinic acid between lead intoxicated dogs which underwent the indicated chelation therapy protocols. There was, however, a trend for higher urinary delta-aminolevulinic acid excretion in those intoxicated dogs undergoing calcium disodium ethylene diamine tetraacetate therapy as opposed to those undergoing penicilamine therapy. There was no significant correlation between blood lead and urinary delta-aminolevulinic acid previous to lead exposure. However, after lead exposure significant correlation was present at days 4, 7, 10 and 14. Certain lead exposed dogs following chelation therapy were noted to have normal blood lead levels but elevated urinary delta-aminolevulinic acid suggesting that blood lead does not always correlate with metabolic effects of lead in the body. Urinary delta-aminolevulinic acid was therefore recommended as an additional laboratory parameter which improved assessment of lead exposure in dogs, particularly in determining adequacy of chelation therapy. PMID:667707

Long term exposure to combination paradigm of environmental enrichment, physical exercise and diet reverses the spatial memory deficits and restores hippocampal neurogenesis in ventral subicular lesioned rats.

Science.gov (United States)

Kapgal, Vijayakumar; Prem, Neethi; Hegde, Preethi; Laxmi, T R; Kutty, Bindu M

2016-04-01

Subiculum is an important structure of the hippocampal formation and plays an imperative role in spatial learning and memory functions. We have demonstrated earlier the cognitive impairment following bilateral ventral subicular lesion (VSL) in rats. We found that short term exposure to enriched environment (EE) did not help to reverse the spatial memory deficits in water maze task suggesting the need for an appropriate enriched paradigm towards the recovery of spatial memory. In the present study, the efficacy of long term exposure of VSL rats to combination paradigm of environmental enrichment (EE), physical exercise and 18 C.W. diet (Combination Therapy - CT) in reversing the spatial memory deficits in Morris water maze task has been studied. Ibotenate lesioning of ventral subiculum produced significant impairment of performance in the Morris water maze and reduced the hippocampal neurogenesis in rats. Post lesion exposure to C.T. restored the hippocampal neurogenesis and improved the spatial memory functions in VSL rats. Our study supports the hypothesis that the combination paradigm is critical towards the development of an enhanced behavioral and cognitive experience especially in conditions of CNS insults and the associated cognitive dysfunctions. Copyright © 2016 Elsevier Inc. All rights reserved.

The Effect of an EDTA-based Chelation Regimen on Patients with Diabetes and Prior Myocardial Infarction in TACT

Science.gov (United States)

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

Combined biotin-terpyridine systems : a new versatile bridge between biology, polymer science and metallo-supramolecular chemistry

NARCIS (Netherlands)

Hofmeier, H.; Pahnke, J.; Weidl, C.H.; Schubert, U.S.

2004-01-01

Biotin, a well-known binding unit for the proteins avidin and streptavidin, was combined with the chelating ligand terpyridine via polymeric and nonpolymeric spacers. An ¿-amino-functionalized terpyridyl-poly(ethylene glycol) was prepared and utilized for complex formation with iron(II), nickel(II),

Effect of the Alkyl Chain Length on the Adsorption Properties of Malonamide Chelating Resins

International Nuclear Information System (INIS)

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

2004-01-01

In order to investigate the effect of the alkyl chain length of malonamide chelating resins on the rate of uptake of U(VI) ions and Ce(III) Ions, lV,N,N',N'-tetraethyl malonamide (TEMA), N,N,N',N'-tetra-n-propyl malonamide (TPrMA), lV,lV,N',N'-tetra-n-butyl malonamide (TBMA) and N,l V,N',N'-tetra-n-pentyl malonamide (Tamp) chelating resins were synthesized by chemically bonding these function groups to CMS-DVB co-polymer beads. N,lV,N',N'-tetraphenyl malonamide (TPhMA) chelating resin was also investigated and the results of these resins were compared with those of N,lY,N',N-tetra methylmalonamide (TMMA) previously reported. The batch technique was used to study the thermodynamic equilibrium, in terms of distribution coefficient, and the kinetics of the adsorption U(VI) and Ce(III) ions from 3 M HNO 3 , Acid, and 3 M NaNO 3 + 0.05 M HNO 3 , Salt, media. The introduction ratio of the function group into the polymer base and the uptake of U(VI) ions and C(III) ions were found to decrease with the increase in the alkyl chain length. The uptake was found to diminish in case of TPhMA resin due to the decrease of the function group ratio and the steric-hinder effect

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.

Science.gov (United States)

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.

Acidizing reservoirs while chelating iron with sulfosalicylic acid

Energy Technology Data Exchange (ETDEWEB)

McLaughlin, W A; Berkshire, D C

1980-09-30

A well treating process is described in which an aqueous solution of a strong acid capable of dissolving solids in a manner increasing the permeability of a subterranean earth formation is injected into a subterranean reservoir that contains an asphaltenic oil. At least the first injected portion of the aqueous acid and a solution or homogeneous dispersion of at least enough 5-sulfosalicylic acid to chelate with and prevent the formation of iron-asphaltene solids are included with substantially all of the ferric ions that become dissolved within the strong acid solution that enters the earth formation. 10 claims.

Phytoextraction of heavy metals from contaminated soil by co-cropping with chelator application and assessment of associated leaching risk.

Science.gov (United States)

Wei, Z B; Guo, X F; Wu, Q T; Long, X X; Penn, C J

2011-08-01

Phytoextraction using hyperaccumulating plants is generally time-consuming and requires the cessation of agriculture. We coupled chelators and a co-cropping system to enhance phytoextraction rates, while allowing for agricultural production. An experiment on I m3 lysimeter beds was conducted with a co-cropping system consisting of the hyperaccumulator Sedum alfredii and low-accumulating corn (Zea Mays, cv. Huidan-4), with addition ofa mixture of chelators (MC), to assess the efficiency of chelator enhanced co-crop phytoextraction and the leaching risk caused by the chelator. The results showed that the addition of MC promoted the growth of S. alfredii in the first crop (spring-summer season) and significantly increased the metal phytoextraction. The DTPA-extractable and total metal concentrations in the topsoil were also reduced more significantly with the addition of MC compared with the control treatments. However, mono-cropped S. alfredii without MC was more suitable for maximizing S. alfredii growth and therefore phytoextraction of Zn and Cd during the autumn-winter seasons. No adverse impact to groundwater due to MC application was observed during the experiments with three crops and three MC applications. But elevated total Cd and Pb concentrations among subsoils compared to the initial subsoil concentrations were found for the co-crop + MC treatment after the third crop.

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

Science.gov (United States)

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.

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

Science.gov (United States)

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.

Novel chelating resin with cyanoguanidine group: Useful recyclable materials for Hg(II) removal in aqueous environment

International Nuclear Information System (INIS)

Ma Xiaojie; Li Yanfeng; Ye Zhengfang; Yang Liuqing; Zhou Lincheng; Wang Liyuan

2011-01-01

A novel chelating resin containing cyanoguanidine moiety has been successfully prepared by the functionalizing reaction of a macroporous bead based on chloromethylated copolymer of styrene-divinylbenzene (CMPS) with dicyandiamide (DCDA) in the presence of phase transfer catalyst. The Fourier transform-infrared spectra (FT-IR) and scanning electron microscopy (SEM) were employed in the characterization of the resulting chelating resin, meanwhile, the adsorption properties of the resin for Hg(II) were investigated by batch and column methods. The results indicated that the resin displayed a marked advantage in Hg(II) binding capacity, and the saturated adsorption capacity estimated from the Langmuir model was dramatically up to 1077 mg g -1 at 45 deg. C. Furthermore, it was found that the resin was able to selectively separate Hg(II) from multicomponent solutions with Zn(II), Cu(II), Pb(II) and Mg(II). The desorption process of Hg(II) was tested with different eluents and the ratio of the highest recovery reached to 96% under eluting condition of 1 M HCl + 10% thiourea. Consequently, the resulting chelating resin would provide a potential application for treatment process of Hg(II) containing wastewater.

Determination of trace elements in seawater by air-flow injection/ICP-MS with chelating resin preconcentration

International Nuclear Information System (INIS)

Lee, Kyue-Hyung; Ohshima, Mitsuko; Motomizu, Shoji

2002-01-01

Multielement determination of major to trace metals in a deep seawater malt was accomplished by inductively coupled plasma-mass spectrometry (ICP-MS) together with inductively coupled plasma-atomic emission spectrometry (ICP-AES). Major elements, such as Na, K, Mg, and Ca, were measured by ICP-AES and normal continuos nebulization ICP-MS after sample dilution by 10 3 -10 6 fold. Fifteen trace elements in the concentrated metal solutions pretreated with cation-exchange resin or chelating resin could be simultaneously determined by air-flow injection/ICP-mass spectrometry (AFI/ICP-MS). Since the injection volume for AFI/ICP-MS was 25 μl, final samples volumes less than 500 μl were enough for several replicate measurements. Three different preconcentration methods assisted with AFI/ICP-MS were examined and could be successfully applied to a deep seawater malt. The analytical results of rate earth elements (REEs) and Co, Ni, Cu, Zn, Cd, and Pb obtained by AFI/ICP-MS coupled with disk filtration method using iminodiacetate (IDA)-type chelating resin were favorably agreed with the data obtained by AFI/ICP-MS coupled with column preconcentration method using chitosan-based chelating resin. (author)

STUDIES REGARDING THE CHELATE-INDUCED HYPERACCUMULATION OF CU AND FE USING LOLIUM PERENNE SPECIES IN MINING AREAS

Directory of Open Access Journals (Sweden)

ANCA-DIANA PRICOP

2009-05-01

Full Text Available The plant capacity to absorb high amounts of metal for a short period of time is the major factor that influences the efficiency of phytoextraction. The hyperaccumulating plants uptake high amounts in their tissues correlated to the metal concentrations in soil. Chelating agents have the capacity to induce the metal accumulation in biomass. They increase metal bioavailability for plants by releasing the metal in accessible forms. The present study emphasizes that in the case of EDTA use, the obtained biomass is smaller compared to the other variants, showing a lower tolerance to this chelating agent of Lolium perenne species. Cu and Fe phytoextraction by Lolium perenne species is higher in the case of EDTA use. Cu bioaccumulation has higher values in variants with compost-sterile mixture ratio of 1:4 in comparison with Fe. In the case of the best compost-sterile mixture ratio of 1:3 the highest biomass is obtained in all the variants, biosolids’ effect being stronger compared to the chelating agent.

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

Science.gov (United States)

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.

Reversible flowchart languages and the structured reversible program theorem

DEFF Research Database (Denmark)

Yokoyama, Tetsuo; Axelsen, Holger Bock; Glück, Robert

2008-01-01

Many irreversible computation models have reversible counterparts, but these are poorly understood at present. We introduce reversible flowcharts with an assertion operator and show that any reversible flowchart can be simulated by a structured reversible flowchart using only three control flow...... operators. Reversible flowcharts are r- Turing-complete, meaning that they can simuluate reversible Turing machines without garbage data. We also demonstrate the injectivization of classical flowcharts into reversible flowcharts. The reversible flowchart computation model provides a theoretical...

Gd (III) chelates adsorbed on TiO2 nanoparticles - promising MRI contrast agent

International Nuclear Information System (INIS)

Rehor, Ivan; Lukes, Ivan; Peters, Joop A.; Jirak, Daniel

2009-01-01

Full text: The project deals with a new contrast agent (CA) for magnetic resonance imaging (MRI). The CA consists of two main parts - diamagnetic core (TiO 2 nanoparticle) and Gd (III) chelates grafted on its surface. The presence of the nanoparticle core is responsible for significant increase of r1 millimolar relaxivity (which corresponds to the efficiency of the CA) due to the slowing down the rotation of the complex in solution. It also affects the biodistribution characteristics of the CA - the ability to penetrate through cell membranes is well known for nanoparticles, making them useful for cell labeling. The structure of the chelate is derived from DOTA ligand, whose Gd (III) complexes are commercially used as MRI CA in human medicine. The connection of the complex to the surface is realized via penylphosphonate, which is attached to the pendant arm of the ligand. Strong interaction of the phosphonate with the TiO 2 surface results in the full surface coverage. The complexation and MRI properties of Gd chelate were studied and exhibit analogy to the complexes of DOTA, The millimolar relaxivity (r1) of the Gd (III) complex significantly increases upon adsorption on the TiO 2 nanoparticles. PVA was added to the colloidal solutions of CA to stabilize them under biological conditions and such stabilized CA was utilized for MRI visualization of rat pancreatic islets (P1). The labeled islets were detected on MR images as hyperintense area and therefore our CA seems to be promising material for cellular MRI

The effects of Fe-chelate type and PH on substrate grown roses

NARCIS (Netherlands)

Voogt, W.; Sonneveld, C.

2009-01-01

Substrate grown roses appear to be susceptible to chlorosis, which indicates problems with Fe or Mn uptake and hence yield reduction. In common practice this problem is often treated by the addition of extra Fe-chelate, or the use of Fe-EDDHA instead of Fe-DTPA. In previous tests, it was shown that

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

Science.gov (United States)

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.

Site-activated chelators derived from anti-Parkinson drug rasagiline as a potential safer and more effective approach to the treatment of Alzheimer's disease.

Science.gov (United States)

Zheng, Hailin; Fridkin, Mati; Youdim, Moussa B H

2010-12-01

chelators can modulate β-amyloid accumulation, protect against tau hyperphosphorylation, and block metal-related oxidative stress, and thereby hold considerable promise as effective anti-AD drugs. At present, a growing interest is focusing on increasing the efficacy and targeting of chelators through drug design. To this end, we have developed a new class of multifunctional prochelators from three FDA- approved drugs rasagiline, rivastigmine, and donepezil or tacrine. HLA20 A was designed by merging the important pharmacophores of rasagiline, rivastigmine, and donepezil into our newly developed multifunctional chelator HLA20. M30D was constructed using the key pharmacophoric moieties from rasagiline, rivastigmine, and tacrine. Experiments showed that both compounds possess potent anti-acetylcholinesterase (AChE) activity in vitro with weak inhibition of butyrylcholinesterase (BuChE), and without significant metal-binding activity. M30D was found also to be a highly potent MAO A inhibitor with moderate inhibition of MAO B in vitro. Both HLA20 and M30D can be activated by inhibition of AChE to release active chelators HLA20 and M30, respectively. HLA20 and M30 have been shown to be able to modulate amyloid precursor protein regulation and beta-amyloid reduction, suppress oxidative stress, and passivate excess metal ions (Fe, Cu, and Zn). Compared with the activated chelator HLA20 or M30, both HLA20A and M30D exhibited lower cytotoxicity in SH-SY5Y neuroblastoma cells, substantiating the prochelator strategy for minimizing toxicity associated with poor targeted chelators.

Structure-activity relationships of novel salicylaldehyde isonicotinoyl hydrazone (SIH analogs: iron chelation, anti-oxidant and cytotoxic properties.

Directory of Open Access Journals (Sweden)

Eliška Potůčková

Full Text Available Salicylaldehyde isonicotinoyl hydrazone (SIH is a lipophilic, tridentate iron chelator with marked anti-oxidant and modest cytotoxic activity against neoplastic cells. However, it has poor stability in an aqueous environment due to the rapid hydrolysis of its hydrazone bond. In this study, we synthesized a series of new SIH analogs (based on previously described aromatic ketones with improved hydrolytic stability. Their structure-activity relationships were assessed with respect to their stability in plasma, iron chelation efficacy, redox effects and cytotoxic activity against MCF-7 breast adenocarcinoma cells. Furthermore, studies assessed the cytotoxicity of these chelators and their ability to afford protection against hydrogen peroxide-induced oxidative injury in H9c2 cardiomyoblasts. The ligands with a reduced hydrazone bond, or the presence of bulky alkyl substituents near the hydrazone bond, showed severely limited biological activity. The introduction of a bromine substituent increased ligand-induced cytotoxicity to both cancer cells and H9c2 cardiomyoblasts. A similar effect was observed when the phenolic ring was exchanged with pyridine (i.e., changing the ligating site from O, N, O to N, N, O, which led to pro-oxidative effects. In contrast, compounds with long, flexible alkyl chains adjacent to the hydrazone bond exhibited specific cytotoxic effects against MCF-7 breast adenocarcinoma cells and low toxicity against H9c2 cardiomyoblasts. Hence, this study highlights important structure-activity relationships and provides insight into the further development of aroylhydrazone iron chelators with more potent and selective anti-neoplastic effects.

Reduced background autofluorescence for cell imaging using nanodiamonds and lanthanide chelates.

Science.gov (United States)

Cordina, Nicole M; Sayyadi, Nima; Parker, Lindsay M; Everest-Dass, Arun; Brown, Louise J; Packer, Nicolle H

2018-03-14

Bio-imaging is a key technique in tracking and monitoring important biological processes and fundamental biomolecular interactions, however the interference of background autofluorescence with targeted fluorophores is problematic for many bio-imaging applications. This study reports on two novel methods for reducing interference with cellular autofluorescence for bio-imaging. The first method uses fluorescent nanodiamonds (FNDs), containing nitrogen vacancy centers. FNDs emit at near-infrared wavelengths typically higher than most cellular autofluorescence; and when appropriately functionalized, can be used for background-free imaging of targeted biomolecules. The second method uses europium-chelating tags with long fluorescence lifetimes. These europium-chelating tags enhance background-free imaging due to the short fluorescent lifetimes of cellular autofluorescence. In this study, we used both methods to target E-selectin, a transmembrane glycoprotein that is activated by inflammation, to demonstrate background-free fluorescent staining in fixed endothelial cells. Our findings indicate that both FND and Europium based staining can improve fluorescent bio-imaging capabilities by reducing competition with cellular autofluorescence. 30 nm nanodiamonds coated with the E-selectin antibody was found to enable the most sensitive detective of E-selectin in inflamed cells, with a 40-fold increase in intensity detected.

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

Science.gov (United States)

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.

Treating Lead Toxicity: Possibilities beyond Synthetic Chelation

Directory of Open Access Journals (Sweden)

Shambhavi Tannir

2013-01-01

Full Text Available Lead, a ubiquitous metal, is one of the most abundant elements present on earth. Its easy availability and cost effectiveness made it an extremely popular component in the industrial revolution. However, its hazardous health effects were not considered at the time. Over the last few decades, with the adverse effects of lead coming to the forefront, nations across the world have started to recognize and treat lead toxicity. The most reliable and used method until now has been chelation therapy. Recent research has suggested the use of natural products and sources to treat lead poisoning with minimal or no side effects. This review has tried to summarize a few of the natural products/sources being investigated by various groups.

Direct nanoimprint lithography of Al2O3 using a chelated monomer-based precursor

International Nuclear Information System (INIS)

Ganesan, Ramakrishnan; Dinachali, Saman Safari; Lim, Su Hui; Saifullah, M S M; He, Chaobin; Low, Hong Yee; Chong, Wee Tit; Lim, Andrew H H; Yong, Jin Jie; Thian, Eng San

2012-01-01

Nanostructuring of Al 2 O 3 is predominantly achieved by the anodization of aluminum film and is limited to obtaining porous anodized aluminum oxide (AAO). One of the main restrictions in developing approaches for direct fabrication of various types of Al 2 O 3 patterns, such as lines, pillars, holes, etc, is the lack of a processable aluminum-containing resist. In this paper, we demonstrate a stable precursor prepared by reacting aluminum tri-sec-butoxide with 2-(methacryloyloxy)ethyl acetoacetate, a chelating monomer, which can be used for large area direct nanoimprint lithography of Al 2 O 3 . Chelation in the precursor makes it stable against hydrolysis whilst the presence of a reactive methacrylate group renders it polymerizable. The precursor was mixed with a cross-linker and their in situ thermal free-radical co-polymerization during nanoimprinting rigidly shaped the patterns, trapped the metal atoms, reduced the surface energy and strengthened the structures, thereby giving a ∼100% yield after demolding. The imprinted structures were heat-treated, leading to the loss of organics and their subsequent shrinkage. Amorphous Al 2 O 3 patterns with line-widths as small as 17 nm were obtained. Our process utilizes the advantages of sol–gel and methacrylate routes for imprinting and at the same time alleviates the disadvantages associated with both these methods. With these benefits, the chelating monomer route may be the harbinger of the universal scheme for direct nanoimprinting of metal oxides. (paper)

Heavy Metals, Cardiovascular Disease, and the Unexpected Benefits of Chelation Therapy.

Science.gov (United States)

Lamas, Gervasio A; Navas-Acien, Ana; Mark, Daniel B; Lee, Kerry L

2016-05-24

This review summarizes evidence from 2 lines of research previously thought to be unrelated: the unexpectedly positive results of TACT (Trial to Assess Chelation Therapy), and a body of epidemiological data showing that accumulation of biologically active metals, such as lead and cadmium, is an important risk factor for cardiovascular disease. Considering these 2 areas of work together may lead to the identification of new, modifiable risk factors for atherosclerotic cardiovascular disease. We examine the history of chelation up through the report of TACT. We then describe work connecting higher metal levels in the body with the future risk of cardiovascular disease. We conclude by presenting a brief overview of a newly planned National Institutes of Health trial, TACT2, in which we will attempt to replicate the findings of TACT and to establish that removal of toxic metal stores from the body is a plausible mechanistic explanation for the benefits of edetate disodium treatment. Copyright © 2016 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Liquid-liquid extraction by reversed micelles in biotechnological processes

Directory of Open Access Journals (Sweden)

Kilikian B. V.

2000-01-01

Full Text Available In biotechnology there is a need for new purification and concentration processes for biologically active compounds such as proteins, enzymes, nucleic acids, or cells that combine a high selectivity and biocompatibility with an easy scale-up. A liquid-liquid extraction with a reversed micellar phase might serve these purposes owing to its capacity to solubilize specific biomolecules from dilute aqueous solutions such as fermentation and cell culture media. Reversed micelles are aggregates of surfactant molecules containing an inner core of water molecules, dispersed in a continuous organic solvent medium. These reversed micelles are capable of selectively solubilizing polar compounds in an apolar solvent. This review gives an overview of liquid-liquid extraction by reversed micelles for a better understanding of this process.

Reverse Algols

Science.gov (United States)

Leung, K. C.

1989-01-01

Reverse Algols, binary systems with a semidetached configuration in which the more massive component is in contact with the critical equipotential surface, are examined. Observational evidence for reverse Algols is presented and the parameters of seven reverse Algols are listed. The evolution of Algols and reverse Algols is discussed. It is suggested that, because reverse Algols represent the premass-reversal semidetached phase of close binary evolution, the evolutionary time scale between regular and reverse Algols is the ratio of the number of confirmed systems of these two Algol types.

Characterization and thermogravimetric analysis of lanthanide hexafluoroacetylacetone chelates.

Science.gov (United States)

Shahbazi, Shayan; Stratz, S Adam; Auxier, John D; Hanson, Daniel E; Marsh, Matthew L; Hall, Howard L

2017-01-01

This work reports the thermodynamic characterizations of organometallic species as a vehicle for the rapid separation of volatile nuclear fission products via gas chromatography due to differences in adsorption enthalpy. Because adsorption and sublimation thermodynamics are linearly correlated, there is considerable motivation to determine sublimation enthalpies. A method of isothermal thermogravimetric analysis, TGA-MS and melting point analysis are employed on thirteen lanthanide 1,1,1,5,5,5-hexafluoroacetylacetone complexes to determine sublimation enthalpies. An empirical correlation is used to estimate adsorption enthalpies of lanthanide complexes on a quartz column from the sublimation data. Additionally, four chelates are characterized by SC-XRD, elemental analysis, FTIR and NMR.

Uranium and neodymium biosorption using novel chelating polysaccharide.

Science.gov (United States)

Elsalamouny, Ahmed R; Desouky, Osman A; Mohamed, Saad A; Galhoum, Ahmed A; Guibal, Eric

2017-11-01

A direct reaction is described to prepare hydrophobic α-aminomethylphosphonic acid as a novel chitosan-based material. It exhibits chelating properties for polyvalent metal ions such as U(VI) and Nd(III) ions. The new sorbent was fully characterized using Elemental analysis, scanning electron microscope (SEM) and FTIR spectra. Different parameters were examined in order to evaluate the optimum conditions for U(VI) and Nd(III) ions biosorption. Sorption mechanisms of metal ions were investigated using kinetic and isotherm models. In addition, the sorbent selectivity was tested for both metal ions together in a binary solution. Copyright © 2017 Elsevier B.V. All rights reserved.