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Sample records for chelation phototherapeutic keratectomy

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

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    Osbel Alfonso Sánchez

    2012-11-01

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

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

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    Kasetsuwan N

    2015-09-01

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

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

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    Rao Srinivas

    1999-01-01

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

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

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    Liang-Mao Li

    2014-01-01

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

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

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    Rapuano, Christopher J.

    2003-01-01

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

  6. New 223-nm excimer laser surgical system for photorefractive keratectomy

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    Bagaev, Sergei N.; Razhev, Alexander M.; Zhupikov, Andrey A.

    1999-02-01

    The using of KrCl (223 nm) excimer laser in ophthalmic devices for Photorefractive Keratectomy (PRK) and phototherapeutic Keratectomy (PTK) is offered. The structure and functions of a new surgical UV ophthalmic laser systems Medilex using ArF (193 nm) or KrCl (223 nm) excimer laser for corneal surgery are presented. The systems Medilex with the new optical delivery system is used for photoablative reprofiling of the cornea to correct refraction errors (myopia, hyperopia and astigmatism) and to treat a corneal pathologies. The use of the 223 nanometer laser is proposed to have advantages over the 193 nanometer laser. The results of application of the ophthalmic excimer laser systems Medilex for treatment of myopia are presented.

  7. Orthoptic Changes following Photorefractive Keratectomy

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    Zhale Rajavi; Nader Nassiri; Monir Azizzadeh; Alireza Ramezani; Mehdi Yaseri

    2011-01-01

    Purpose: To report orthoptic changes after photorefractive keratectomy (PRK). Methods: This interventional case series included 297 eyes of 150 patients scheduled for PRK. Complete ophthalmologic evaluations focusing on orthoptic examinations were performed before and 3 months after PRK. Results: Before PRK, 2 (1.3%) patients had esotropia which remained unchanged; 3 (2%) patients had far exotropia which improved after the procedure. Of 12 cases (8%) with initial exotropia at near, 3 ...

  8. Orthoptic Changes following Photorefractive Keratectomy

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    Zhale Rajavi

    2011-01-01

    Full Text Available Purpose: To report orthoptic changes after photorefractive keratectomy (PRK. Methods: This interventional case series included 297 eyes of 150 patients scheduled for PRK. Complete ophthalmologic evaluations focusing on orthoptic examinations were performed before and 3 months after PRK. Results: Before PRK, 2 (1.3% patients had esotropia which remained unchanged; 3 (2% patients had far exotropia which improved after the procedure. Of 12 cases (8% with initial exotropia at near, 3 (2% cases became orthophoric, however 6 patients (4% developed new near exotropia. A significant reduction in convergence and divergence amplitudes (P 10 cm which remained unchanged after surgery. Out of 9 (6% patients with baseline stereopsis > 60 seconds of arc, 2 (1.33% showed an improvement in stereopsis following PRK. No patient developed diplopia postoperatively. Conclusion: Preexisting strabismus may improve or remain unchanged after PRK, and new deviations can develop following the procedure. A decrease in fusional amplitudes, an increase in NPC, and an improvement in stereopsis may also occur after PRK. Preoperative evaluation of orthoptic status for detection of baseline abnormalities and identification of susceptible patients seem advisable.

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

    Institute of Scientific and Technical Information of China (English)

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

    2003-01-01

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

  10. Bilateral Nocardia Keratitis after Photorefractive Keratectomy

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    Amir Faramarzi

    2012-01-01

    Full Text Available Purpose: To report the clinical, confocal scan, and histopathologic features of Nocardia keratitis in a patient who developed bilateral infection following photorefractive keratectomy (PRK. Case Report: A 23-year-old woman underwent bilateral PRK for low myopia. On postoperative day 3, dense central stromal infiltrates were noticed in both eyes. Empirical antibiotic therapy was initiated which was converted into specific therapy after a definite diagnosis was made based on clinical features and confirmed by confocal scan and histopathologic findings. Clinical and confocal scan features were consistent with the diagnosis of Nocardia keratitis, and topical 2% amikacin eye drops were started. Because of poor response to medical therapy, lamellar keratectomy was performed in both eyes which shortened the treatment course. Histopathologic examination reconfirmed the initial diagnosis. Conclusion: Familiarity with clinical and confocal scan features facilitates early diagnosis of Nocardia keratitis leading to proper management and hence a rapid therapeutic response.

  11. Bilateral Nocardia Keratitis after Photorefractive Keratectomy

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    Faramarzi, Amir; Feizi, Sepehr; Javadi, Mohammad-Ali; Rezaei Kanavi, Mozhgan; Yazdizadeh, Forouzan; Moein, Hamid-Reza

    2012-01-01

    Purpose To report the clinical, confocal scan, and histopathologic features of nocardia keratitis in a patient who developed bilateral infection following photorefractive keratectomy (PRK). Case Report A 23-year-old woman underwent bilateral PRK for low myopia. On postoperative day 3, dense central stromal infiltrates were noticed in both eyes. Empirical antibiotic therapy was initiated which was converted into specific therapy after a definite diagnosis was made based on clinical features and confirmed by confocal scan and histopathologic findings. Clinical and confocal scan features were consistent with the diagnosis of Nocardia keratitis, and topical 2% amikacin eye drops were started. Because of poor response to medical therapy, lamellar keratectomy was performed in both eyes which shortened the treatment course. Histopathologic examination reconfirmed the initial diagnosis. Conclusion Familiarity with clinical and confocal scan features facilitates early diagnosis of Nocardia keratitis leading to proper management and hence a rapid therapeutic response. PMID:23275825

  12. CORNEAL HAZE FOLLOWING PHOTO REFRACT IVE KERATECTOMY

    OpenAIRE

    Atul; Superna; Pervaiz

    2015-01-01

    To assess the incidence of corneal haze following surface ablation in (PRK) in high myopic patients (≥6D). METHODS: In this prospective clinical study , 25 patients with high myopia (≥6D) that is 50 eyes in total , underwent photorefractive keratectomy by Schwind Amaris 500E laser machine. At the initial presentation , each patient underwent a detailed clinical evaluation that included recording of medical history , detailed ocular history , ...

  13. Phototherapeutic treatment of lymphedema and other complications after mastectomy

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

    2000-05-01

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

  14. The Antifibrosis Effects of Peroxisome Proliferator-Activated Receptor δ on Rat Corneal Wound Healing after Excimer Laser Keratectomy

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    Yun Gu

    2014-01-01

    Full Text Available Corneal stromal fibrosis characterized by myofibroblasts and abnormal extracellular matrix (ECM is usually the result of inappropriate wound healing. The present study tested the hypothesis that the ligand activation of peroxisome proliferator-activated receptor (PPAR δ had antifibrosis effects in a rat model of corneal damage. Adult Sprague-Dawley rats underwent bilateral phototherapeutic keratectomy (PTK. The eyes were randomized into four groups: PBS, GW501516 (a selective agonist of PPARδ, GSK3787 (a selective antagonist of PPARδ, or GW501516 combined with GSK3787. The agents were subconjunctivally administered twice a week until sacrifice. The cellular aspects of corneal wound healing were evaluated with in vivo confocal imaging and postmortem histology. A myofibroblast marker (α-smooth muscle actin and ECM production (fibronectin, collagen type III and collagen type I were examined by immunohistochemistry and RT-PCR. At the early stages of wound healing, GW501516 inhibited reepithelialization and promoted angiogenesis. During the remodeling phase of wound healing, GW501516 attenuated the activation and proliferation of keratocytes, which could be reversed by GSK3787. GW501516 decreased transdifferentiation from keratocytes into myofibroblasts, ECM synthesis, and corneal haze. These results demonstrate that GW501516 controls corneal fibrosis and suggest that PPARδ may potentially serve as a therapeutic target for treating corneal scars.

  15. Therapeutic keratectomy for Mycobacterium abscessus keratitis after LASIK.

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    Sun, Yi-Chen; Wang, I-Jong; Chen, Wei-Li; Hu, Fung-Rong

    2003-11-01

    We report successful treatment of a case of Mycobacterium abscessus keratitis after laser in situ keratomileusis (LASIK) with therapeutic lamellar keratectomy. A 34-year-old woman developed a 2 x 2 mm feathery infiltration within the interface inferior to the pupil margin with mild inflammation of the conjunctiva in her left eye 40 days after LASIK surgery. Bacterial culture from the infiltrates of the interface of the stromal bed revealed Mycobacterium abscessus. After combination antibiotic therapy including amikacin and ciprofoxacin was given for 6 weeks, infiltration persisted despite the development of necrosis in the flap tissue. Therapeutic lamellar keratectomy combined with flap removal was performed. No recurrence was found 1 year after the surgery. Therapeutic lamellar keratectomy with flap removal can provide an effective treatment modality for the management of post-LASIK Mycobacterium abscessus keratitis that is unresponsive to medical treatment. PMID:14724729

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

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

    2016-07-01

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

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

    OpenAIRE

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

    2016-01-01

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

  18. Corneal topography of excimer laser photorefractive keratectomy.

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    Klyce, S D; Smolek, M K

    1993-01-01

    The application of the 193 nm excimer laser for keratorefractive surgery promises to deliver a higher degree of precision and predictability than traditional procedures such as radial keratotomy. The development and evaluation of keratorefractive surgery have benefited from the parallel advances made in the field of corneal topography analysis. We used the Computed Anatomy Topography Modeling System (TMS-1) to analyze a Louisiana State University (LSU) Eye Center series of patients who had photorefractive keratectomy for the treatment of myopia with the VISX Twenty/Twenty excimer laser system. The excimer ablations were characterized by a relatively uniform distribution of surface powers within the treated zone. In the few cases that exhibited marked refractive regression, corneal topography analysis showed correlative changes. With topographical analysis, centration of the ablations relative to the center of the pupil could be evaluated. Marked improvement in centration occurred in the patients of LSU Series IIB in which the procedure to locate the point on the cornea directly over the pupil's center during surgery was refined. Corneal topographical analysis provides objective measures of keratorefractive surgical results and is able to measure the precise tissue removal effect of excimer laser ablation without the uncertainties caused by measuring visual acuity alone. Our observations forecast the need for improved aids to center the laser ablations and for the development of a course of treatment to prevent post-ablation stromal remodeling. PMID:8450433

  19. Comparison Of Photorefractive Keratectomy Versus Femtosecond Lasik For Correction Myopia

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    Salem Ali Alsalem; Ali Hassan Almordef; Zaid Mohammed Alsaqour

    2013-01-01

    This study aimed to compare and determine the differences in visual acuity, complications and higher order aberration (HOAs) in eyes with stable myopia undergoing either photorefractive keratectomy (PRK) or femtosecond Lasik (Fs Lasik) flaps were created with an intended thickness of 100 µm, diameter of 8.4 to 9.0 mm, superior hinge, at one month postoperatively. Prospective study, randomized pilot study, refractive surgery was performed on 40 eyes: 20 eyes with PRK and 20 eyes with Fs Lasik....

  20. Use of loteprednol for routine prophylaxis after photorefractive keratectomy

    OpenAIRE

    Moshirfar M; Hsu M; Sikder S; Christiansen SM; Mifflin MD; Leishman LL

    2012-01-01

    Mark D Mifflin1, Lisa L Leishman1, Steven M Christiansen1, Shameema Sikder2, Maylon Hsu1, Majid Moshirfar11Department of Ophthalmology, John A Moran Eye Center, University of Utah School of Medicine, Salt Lake City, UT, 2Wilmer Eye Institute, Johns Hopkins Hospital, Johns Hopkins University, Baltimore, MD, USABackground: The purpose of this work is to report our experience using loteprednol 0.5% for routine prophylaxis after photorefractive keratectomy in an academic refractive surgery center...

  1. Fellow eye treatment in excimer photo refractive keratectomy

    OpenAIRE

    Rao Srinivas; Mukesh Bickol; Saraniya A; Sitalakshmi G; Padmanabhan Prema

    2000-01-01

    Purpose: To describe symmetry of response in fellow eyes of patients undergoing photorefractive keratectomy (PRK) for myopia, analyse the risk factors leading to asymmetry in response and to determine if delayed treatment of the second eye increases safety and predictability of PRK. Methods: Retrospective review of case records of 133 patients who underwent bilateral myopic PRK and had a minimum follow up of 6 months in both eyes. Results: Postoperative uncorrected visual acuity, spherical eq...

  2. CORNEAL HAZE FOLLOWING PHOTO REFRACT IVE KERATECTOMY

    Directory of Open Access Journals (Sweden)

    Atul

    2015-02-01

    Full Text Available To assess the incidence of corneal haze following surface ablation in (PRK in high myopic patients (≥6D. METHODS: In this prospective clinical study , 25 patients with high myopia (≥6D that is 50 eyes in total , underwent photorefractive keratectomy by Schwind Amaris 500E laser machine. At the initial presentation , each patient underwent a detailed clinical evaluation that included recording of medical history , detailed ocular history , Snellen visual acuity testing , and thorough anterior segment by slit - lamp bi o - microscopy and posterior segment examination with indirect ophthalmoscopy were done. Corneal topography and pachymetry were also done. The patient is followed up at 1week to observe for re - epithelialization and then at 1 , 3 and 6 months for observation o f haze under slit - lamp examinamination. RESULTS: In our study of 25 patients , that is 50 eyes in total were divided into 3 groups depending upon the spherical equivalence. Group 1 between 6.00 - 7.00D , group 2 between 7.00 - 8.00D , and in group 3 more than 8D (≥8.00D. Over 6months period of follow up a significant haze was noted as the patient’s refractive error increased. Out of 50 eyes , 11 eyes (84.6% with spherical equivalence of 6.00 - 7.00D (group 1 had grade 0 , 8 eyes (66.6% with spherical equivalence o f 7.00 - 8.00D (group 2 had grade 0 , and 6 eyes (24% with spherical equivalence ≥8.00D (group 3 had grade 0. Thus , the results show that there has been a significant decrease in the eyes with no corneal haze as the refractive error increased. Eyes with gr ade 1 haze in group1 were 2 (15.3% , group 2 were 3 (25% , and group 3 were 7 (28%. These results showed that the incidence of grade 1 haze increased with increase in spherical equivalence. Eyes with grade 2 haze in group 1 were 0 (0% , group 2 were 1 (8. 3% , group 3 were 10 (40%. Thus , it is seen that grade 2 haze was not noted in eyes with spherical equivalence between 6.00 - 7.00D , but were

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

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

    1989-01-01

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

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

    Science.gov (United States)

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

    2001-05-01

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

  5. Optical comparison of multizone and single-zone photorefractive keratectomy

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    Gonzalez-Cirre, Xochitl; Manns, Fabrice; Rol, Pascal O.; Parel, Jean-Marie A.

    1997-05-01

    The purpose is to calculate and compare the point-spread function and the central ablation depth (CAD) of a paraxial eye model after photo-refractive keratectomy (PRK), with single and multizone treatments. A modified Le Grand-El Hage paraxial eye model, with a pupil diameter ranging from 2 to 8 mm was used. Ray-tracing was performed for initial myopia ranging from 1 to 10D; after single zone PRK; after double zone PRK; and after tripe zone PRK. The ray-tracing of a parallel incident beam was calculated by using the paraxial matrix method. At equal CAD, the optical image quality is better after single zone treatments. Multizone treatments do not seem to be advantageous optically.

  6. Results of excimer-laser-performed photorefractive keratectomy operations

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    Ferincz, Istvan E.; Ratkay-Traub, Imola; Dinnyes, Maria

    1998-08-01

    We have performed excimer laser photorefractive keratectomy operations with a Schwind Keratom 2F to correct near- sightedness. 613 eyes of 348 patients were treated by this ablation method. We have selected 318 case, where the follow-up was at least 6 months long. The intended corrections were in the range of -1.75 D to -9.0 D for myopia. The optical zones were 5.5 and 6.0 mm. We present various results of the treatments: change of visual acuity, residual spherical refractive error, time valuation of healing, and ablation speed. We have found that the ablation speed of human cornea is depends on the age of patients. An equation is also presented to describe the relation between age and ablation speed.

  7. Chelation in Metal Intoxication

    OpenAIRE

    Flora, Swaran J.S.; Vidhu Pachauri

    2010-01-01

    Chelation therapy is the preferred medical treatment for reducing the toxic effects of metals. Chelating agents are capable of binding to toxic metal ions to form complex structures which are easily excreted from the body removing them from intracellular or extracellular spaces. 2,3-Dimercaprol has long been the mainstay of chelation therapy for lead or arsenic poisoning, however its serious side effects have led researchers to develop less toxic analogues. Hydrophilic chelators like meso-2,3...

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

    International Nuclear Information System (INIS)

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

  9. Superficial keratectomy and 360º conjunctival flap for bullous keratopathy in a dog: a case report

    Directory of Open Access Journals (Sweden)

    J.P.D. Ortiz

    2011-06-01

    Full Text Available A case of a two-year-old male Pinscher with a history of discomfort in the right eye was reported. The left eye had been enucleated by the referring veterinarian due to the same symptom with unsuccessful clinical treatment. The Schirmer tear test value was elevated and a decreased intraocular pressure was observed by applanation tonometry. Biomicroscopy revealed profuse corneal edema and keratoconus and fluorescein staining was negative. Gonioscopy and ophthalmoscopy did not provide any relevant data due to the corneal alterations. Bullous keratopathy was diagnosed. Surgery was performed in two steps: 1 superficial keratectomy and 360º conjunctival flap, and 2 superficial keratectomy to restore corneal transparency. Thirty days after the second superficial keratectomy, the third eyelid flap was removed. Conjunctivalization of the upper nasal quadrant of the cornea was observed. The axial portion of the cornea was transparent and vision was restored.

  10. Effect of onion extract on corneal haze suppression after air assisted lamellar keratectomy

    OpenAIRE

    Kim, Soohyun; Park, Young Woo; LEE, Euiri; PARK, Sang Wan; Park, Sungwon; Noh, Hyunwoo; Kim, Jong Whi; Seong, Je Kyung; SEO, Kangmoon

    2015-01-01

    This study evaluated the effect of onion extract on corneal haze suppression after applying the air assisted lamellar keratectomy. The air assisted lamellar keratectomy was performed on 24 canine eyes. They were treated with an artificial tear (group C), prednisolone acetate (group P), onion extract (group O) and TGF-β1 (group T) three times per day from 7 to 28 days after the surgery. Corneal haze occurred on the all eyes and was observed beginning 7 days after the surgery. The haze was sign...

  11. [Corneal reinnervation after lamellar keratoplasty in comparison with epikeratophakia and photorefractive keratectomy].

    Science.gov (United States)

    Böhm, A; Kohlhaas, M; Kliefoth, U; Draeger, J; Lombardi, M; Abbondanza, M; Zuppardo, M; Görne, M

    1994-10-01

    Corneal sensitivity was examined with the Draeger aesthesiometer in 8 patients after lamellar keratoplasty, 7 patients after epikeratophakia and 82 patients after photorefractive keratectomy. We examined 9 different points in each cornea. The corneal sensitivity of patients after lamellar keratoplasty was normal 1 year after operation. A correlation with the depth of the lamellar dissection was demonstrated. Patients with lamellar keratoplasty with pterygium showed a sensitivity decrease in the nasal parts of the lenticule even after one year. Three years after epikeratophakia the corneal center was still not sensitive. After photorefractive keratectomy of more than 10 D, corneal hyposensitivity was shown even 2 years after operation. PMID:7812096

  12. Comparison Of Photorefractive Keratectomy Versus Femtosecond Lasik For Correction Myopia

    Directory of Open Access Journals (Sweden)

    Salem Ali Alsalem

    2013-10-01

    Full Text Available This study aimed to compare and determine the differences in visual acuity, complications and higher order aberration (HOAs in eyes with stable myopia undergoing either photorefractive keratectomy (PRK or femtosecond Lasik (Fs Lasik flaps were created with an intended thickness of 100 µm, diameter of 8.4 to 9.0 mm, superior hinge, at one month postoperatively. Prospective study, randomized pilot study, refractive surgery was performed on 40 eyes: 20 eyes with PRK and 20 eyes with Fs Lasik. Primary outcomes measures were uncorrected distance visual acuity (UDVA, corrected distance visual acuity (CDVA and complications. Higher order aberration was as a secondary measurement. At one month postoperative in Fs Lasik eyes more improvement UDVA, CDVA was statically different between group at 1 month 25% of PRK group losing a line or more from preoperative while 10%of Fs group lost only 1 line .35% of Fs group gained a line by a month compared of 10%of PRK group .Types of complications different between groups: eight eyes in Fs Lasik group experiencing complications including diffuse lamellar keratitis (DLK with no loss of UDVA or CDVA. There were slightly significant differences between groups in any HOAs, spherical and coma aberrations were increased compared with preoperative conditions. At 1-month follow-up, Fs Lasik group demonstrated clinically and statistically significant better visual acuity and higher order aberrations HOA than the PRK group with differences in experienced complications.

  13. Analysis of corneal esthesia in patients undergoing photorefractive keratectomy

    Directory of Open Access Journals (Sweden)

    Elmar Torres Neto

    2015-12-01

    Full Text Available ABSTRACT Purpose: To quantitatively analyze corneal esthesia in patients undergoing photorefractive keratectomy (PRK surgery. Methods: Forty-five patients selected for PRK in one eye underwent corneal esthesia using a Cochet-Bonnet esthesiometer preoperatively and 30 and 90 days postoperatively. Patients with a refractive diopter error of 4 or greater received intraoperative 0.02% mitomycin C for 20 s. Results: Twenty-four (53.3% of the 45 eyes received intraoperative 0.02% mitomycin. Decreased sensitivity was observed on postoperative day 30. By postoperative day 90, corneal esthesia had normalized but remained 14.9% lower than preoperative levels. In the mitomycin group, no recovery of corneal esthesia to normal sensitivity levels was observed. The mean esthesiometer level was 39.2 mm on postoperative day 90 (P<0.001. Conclusions: The results of the present study demonstrate recovery of corneal esthesia to normal levels at 90 days postoperatively in patients who did not receive mitomycin C. In patients administered mitomycin C, a 23.59% reduction in the corneal touch threshold was observed compared with preoperative levels indicating a failure of recovery to normal levels.

  14. Spot diameters for scanning photorefractive keratectomy: a comparative study

    Science.gov (United States)

    Manns, Fabrice; Parel, Jean-Marie A.

    1998-06-01

    Purpose: The purpose of this study was to compare with computer simulations the duration, smoothness and accuracy of scanning photo-refractive keratectomy with spot diameters ranging from 0.2 to 1 mm. Methods: We calculated the number of pulses per diopter of flattening for spot sizes varying from 0.2 to 1 mm. We also computed the corneal shape after the correction of 4 diopters of myopia and 4 diopters of astigmatism with a 6 mm ablation zone and a spot size of 0.4 mm with 600 mJ/cm2 peak radiant exposure and 0.8 mm with 300 mJ/cm2 peak radiant exposure. The accuracy and smoothness of the ablations were compared. Results: The repetition rate required to produce corrections of myopia with a 6 mm ablation zone in a duration of 5 s per diopter is on the order of 1 kHz for spot sizes smaller than 0.5 mm, and of 100 Hz for spot sizes larger than 0.5 mm. The accuracy and smoothness after the correction of myopia and astigmatism with small and large spot sizes were not significantly different. Conclusions: This study seems to indicate that there is no theoretical advantage for using either smaller spots with higher radiant exposures or larger spots with lower radiant exposures. However, at fixed radiant exposure, treatments with smaller spots require a larger duration of surgery but provide a better accuracy for the correction of astigmatism.

  15. Macrocyclic bifunctional chelating agents

    Science.gov (United States)

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

    1987-01-01

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

  16. Straylight before and after hyperopic laser in situ keratomileusis or laser-assisted subepithelial keratectomy

    NARCIS (Netherlands)

    R. Lapid-Gortzak; J.W. van der Linden; I.J.E. van der Meulen; C.P. Nieuwendaal; M.P. Mourits; T.J.T.P. van den Berg

    2010-01-01

    PURPOSE To compare straylight values before and 3 months after hyperopic laser in situ keratomileusis (LASIK) or laser-assisted subepithelial keratectomy (LASEK) and determine the cause of any change SETTING Private refractive surgery clinic, Driebergen, The Netherlands DESIGN Comparative case serie

  17. Straylight measurements in laser in situ keratomileusis and laser-assisted subepithelial keratectomy for myopia

    NARCIS (Netherlands)

    R. Lapid-Gortzak; J.W. van der Linden; I. van der Meulen; C. Nieuwendaal; T. Berg

    2010-01-01

    PURPOSE: To compare straylight values before and 3 months after laser in situ keratomileusis (LASIK) and laser-assisted subepithelial keratectomy (LASEK) and to analyze the causes of any change. SETTING: Private refractive surgery clinic, Driebergen, The Netherlands. METHODS: Straylight was measured

  18. Keratopathy and pachymetric changes after photorefractive keratectomy and vitrectomy with silicone oil injection

    DEFF Research Database (Denmark)

    Buch, H; Vesti Nielsen, N

    2000-01-01

    We present a man who, after bilateral excimer laser photorefractive keratectomy (PRK) for high myopia in the right eye, had repeated retinal detachment surgery with lensectomy and injection of silicone oil. Visual acuity fluctuated in accordance with significant central corneal thickness diurnal...

  19. Fellow eye treatment in excimer photo refractive keratectomy

    Directory of Open Access Journals (Sweden)

    Rao Srinivas

    2000-01-01

    Full Text Available Purpose: To describe symmetry of response in fellow eyes of patients undergoing photorefractive keratectomy (PRK for myopia, analyse the risk factors leading to asymmetry in response and to determine if delayed treatment of the second eye increases safety and predictability of PRK. Methods: Retrospective review of case records of 133 patients who underwent bilateral myopic PRK and had a minimum follow up of 6 months in both eyes. Results: Postoperative uncorrected visual acuity, spherical equivalent (SE refraction within ±1D of emmetropia, best-corrected visual acuity (BCVA and corneal haze were not significantly different in fellow eyes of patients undergoing PRK for myopia. Of 87 eyes in group 1 (myopia <6D, 96.6% had uncorrected visual acuity ≥6/ 12, 89.7% were within ±1D of emmetropia, none lost ≥1 line BCVA, and none had haze ≥grade 3. Similar results for 98 eyes in group II (myopia 6 to 9.9D were 75.6%, 55.1%, 2.0% and 2.0% respectively. For 81 eyes in group III (myopia ≥ 10D the results were 42.7%, 33.3%, 8.6%, and 4.9% respectively. Among 84 patients with similar preoperative myopia in both eyes, 54 (64.3% patients had a postoperative SE difference ≤ ID in fellow eyes. Risk factors for asymmetric response among fellow eyes included increasing preoperative myopia (p<0.001 and dissimilar treatment technique in the two eyes (p=0.03. Corneal haze did not increase significantly after the third postoperative month. Conclusion: This study demonstrates that considerable symmetry of response exists in fellow eyes of patients undergoing myopic PRK. Early PRK in the fellow eye of patients with < 6 D myopia is safe and allows quick visual rehabilitation of the patient. In patients with myopia ≥6D, a 3-month interval before treating the second eye may improve the safety of the procedure.

  20. 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...... 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...

  1. Ferrocene base metal chelates

    International Nuclear Information System (INIS)

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

  2. 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.

  3. Early Postoperative Pain and Visual Outcomes Following Epipolis-Laser In Situ Keratomileusis and Photorefractive Keratectomy

    OpenAIRE

    Kim, Jae-Hyung; Lee, Jooeun; Kim, Jae Yong; Tchah, Hungwon

    2010-01-01

    Purpose To compare early postoperative pain and visual outcomes after epipolis-laser in situ keratomileusis (epi-LASIK) and photorefractive keratectomy (PRK) in the treatment of myopia. Methods A retrospective chart review was designed and included 49 eyes in 30 patients who underwent epi-LASIK and 54 eyes in 29 patients who underwent PRK. During the early postoperative period (days 1 to 5), pain, uncorrected visual acuity (UCVA), and time to epithelial healing were recorded. Visual outcomes ...

  4. Comparative study of two silicone hydrogel contact lenses used as bandage contact lenses after photorefractive keratectomy

    OpenAIRE

    Hasan Razmjoo; Elham Abdi; Sayna Atashkadi; Akhlaghi M Reza; Peyman A Reza; Mojtaba Akbari

    2012-01-01

    Background: Silicon hydrogel bandage contact lenses are used to enhance epithelial healing, control surface-generated pain, and prevent epithelial erosions after refractive surgery. Considering the importance of faster reepithelialization in preventing complications of photorefractive keratectomy (PRK) and the fact that the features and specifications of these commercially-available lenses are different and their performance as a postoperative bandage lenses would be different also, the aim o...

  5. Excimer retreatment for scarring and regression after photorefractive keratectomy for myopia.

    OpenAIRE

    SUTTON, G; Kalski, R S; Lawless, M A; Rogers, C.

    1995-01-01

    AIMS/BACKGROUND--Scarring associated with regression of refractive effect can occur after photorefractive keratectomy (PRK) for myopia. The experience of treating these complications is reported. METHODS--Eighteen of 285 eyes (6.3%) were retreated with the excimer laser. Age, sex, preoperative primary treatment keratometry, pre-primary treatment, pre-retreatment and post-retreatment spherical equivalents, best corrected and uncorrected visual acuities were recorded and analysed. RESULTS--At 6...

  6. Comments on chelation therapy

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

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

    1996-01-01

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

  8. 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...

  9. Keratoconus and corneal stability after radial keratectomy in the fellow eye: case report

    Directory of Open Access Journals (Sweden)

    Jacqueline Martins Sousa

    2013-06-01

    Full Text Available Keratoconus has usually been described as bilateral but asymmetric disease. Corneal ectasia is one of the long-term complications of modern refractive surgery, especially those submitted to laser in situ keratomileusis (LASIK. We describe a patient with keratoconus in the right eye that was submitted to radial keratectomy (RK in the left eye 19 years ago with no progression of the ectatic cornea and no complications related to the refractive surgery. Because unilateral keratoconus is rare, we believe that RK was performed on an already ectatic cornea (not clinically detected or with fruste keratoconus. However, neither corneal ectasia progressed, nor ectasia was induced by RK in the fellow eye.

  10. Chelated minerals for poultry

    Directory of Open Access Journals (Sweden)

    SL Vieira

    2008-06-01

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

  11. Effect of onion extract on corneal haze suppression after air assisted lamellar keratectomy.

    Science.gov (United States)

    Kim, Soohyun; Park, Young Woo; Lee, Euiri; Park, Sang Wan; Park, Sungwon; Noh, Hyunwoo; Kim, Jong Whi; Seong, Je Kyung; Seo, Kangmoon

    2016-04-01

    This study evaluated the effect of onion extract on corneal haze suppression after applying the air assisted lamellar keratectomy. The air assisted lamellar keratectomy was performed on 24 canine eyes. They were treated with an artificial tear (group C), prednisolone acetate (group P), onion extract (group O) and TGF-β1 (group T) three times per day from 7 to 28 days after the surgery. Corneal haze occurred on the all eyes and was observed beginning 7 days after the surgery. The haze was significantly decreased in groups P and O from day 14 compared with the group C using the clinical (group P; P=0.021, group O; P=0.037) and objective evaluation method (group P; P=0.021, group O; P=0.039). In contrast, it was significantly increased in group T from day 14 compared with group C based on the clinical (P=0.002) and objective evaluation method (Peuthanasia, and immunohistochemistry with α-SMA antibodies was done. The total green intensity for α-SMA was significantly more expressed in group T and significantly less expressed in groups P and O than in group C. Onion extract could have potential as a therapeutic in preventing corneal haze development by suppressing the differentiation of fibroblasts into myofibroblasts. PMID:26607134

  12. Spherical and aspherical photorefractive keratectomy and laser in-situ keratomileusis for moderate to high myopia: two prospective, randomized clinical trials. Summit technology PRK-LASIK study group.

    OpenAIRE

    Steinert, R F; Hersh, P S

    1998-01-01

    OBJECTIVE: Determine the outcomes of single-zone photorefractive keratectomy (SZPRK), aspherical photorefractive keratectomy (ASPRK), and laser in-situ keratomileusis (LASIK) for the correction of myopia between -6 and -12 diopters. DESIGN: Two simultaneous prospective, randomized, multi-center clinical trials. PARTICIPANTS: 286 first-treated eyes of 286 patients enrolled in one of two studies. In Study I, 134 eyes were randomized to SZPRK (58 eyes) or ASPRK (76 eyes). In Study II, 152 eyes w...

  13. Clinical research on high oxygen permeable contact lens used after photorefractive keratectomy surgery

    Directory of Open Access Journals (Sweden)

    Hao-Jiang Yang

    2013-07-01

    Full Text Available AIM: To evaluate the outcome of high oxygen permeable contact lens used after photorefractive keratectomy(PRKsurgery.METHODS: Totally 95 patients(190 eyesafter PRK were included. Patients were randomly assigned to wear high oxygen permeable contact lens in one eye and normal lens in the fellow eye after surgery. The subjective symptoms and corneal epithelial status after PRK were evaluated. Uncorrected visual acuity(UCVAand haze were assessed at 6 months after PRK.RESULTS: Complaints of blurred vision, pain and photophobia were statistically more among the normal lens group than high oxygen permeable contact lens group(PPP=0.35. There was no difference in UCVA and haze 6 months after surgery(P=0.55. CONCLUSION: High oxygen permeable contact lens can significantly produce less the corneal irritated symptoms, reduce the discomfort feeling and promote healing of corneal epithelium after PRK.

  14. Factors affecting the outcome of excimer laser photorefractive keratectomy: a preliminary multivariable regression analysis

    Science.gov (United States)

    Maguen, Ezra I.; Papaioannou, Thanassis; Nesburn, Anthony B.; Salz, James J.; Warren, Cathy; Grundfest, Warren S.

    1996-05-01

    Multivariable regression analysis was used to evaluate the combined effects of some preoperative and operative variables on the change of refraction following excimer laser photorefractive keratectomy for myopia (PRK). This analysis was performed on 152 eyes (at 6 months postoperatively) and 156 eyes (at 12 months postoperatively). The following variables were considered: intended refractive correction, patient age, treatment zone, central corneal thickness, average corneal curvature, and intraocular pressure. At 6 months after surgery, the cumulative R2 was 0.43 with 0.38 attributed to the intended correction and 0.06 attributed to the preoperative corneal curvature. At 12 months, the cumulative R2 was 0.37 where 0.33 was attributed to the intended correction, 0.02 to the preoperative corneal curvature, and 0.01 to both preoperative corneal thickness and to the patient age. Further model augmentation is necessary to account for the remaining variability and the behavior of the residuals.

  15. Photorefractive keratectomy: measuring the matrix metalloproteinase activity and chondroitin sulfate concentration in tear fluid

    Directory of Open Access Journals (Sweden)

    Tetsuya Mutoh

    2010-09-01

    Full Text Available Tetsuya Mutoh, Masaya Nishio, Yukihiro Matsumoto, Kiyomi Arai, Makoto ChikudaDepartment of Ophthalmology, Dokkyo Medical University Koshigaya Hospital, Saitama, JapanAbstract: We herein report the case of a 20-year-old man who underwent a photorefractive keratectomy (PRK. We measured matrix metalloproteinase-9 (MMP-9 activity and chondroitin 4 sulfate and chondroitin 6 sulfate concentrations in tear fluid. Tear fluid was collected preoperatively via microcapillary tube, and was collected postoperatively on the first and fourth days, and after one week, one month, three months, and six months. Samples were formulated by dilution with 200 µL of saline. MMP-9 activity was analyzed by an enzyme immunocapture activity assay, and the concentrations of chondroitin sulfate were analyzed by enzyme-linked immunosorbent assay. No complications were observed after surgery, except for a minimal subepithelial haze. Although MMP-9 activity changed on the fourth postoperative day, the activity changed only minimally at this time. Chondroitin 4 sulfate concentrations in tear fluid increased dramatically from one week to one month, decreased transiently at three months, and increased by six months. The chondroitin 6 sulfate concentration did not normalize within one week, and decreased from one week to three months compared with the preoperative score, and was close to the preoperative score at six months. We conclude that corneal wound healing was still incomplete six months after PRK, and chondroitin 4 sulfate appears to be critical in this process.Keywords: matrix metalloproteinase, chondroitin sulfate, human tear fluid, photorefractive keratectomy, corneal wound healing

  16. Some aspects of chelation chemistry

    International Nuclear Information System (INIS)

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

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

    OpenAIRE

    Smith, Donald; Strupp, Barbara J.

    2013-01-01

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

  18. Analysis of the keratocyte apoptosis, keratocyte proliferation, and myofibroblast transformation responses after photorefractive keratectomy and laser in situ keratomileusis.

    OpenAIRE

    Wilson, Steven E

    2002-01-01

    PURPOSE: To test the hypothesis that (1) there are quantitative differences in the cellular responses in the corneal stroma after photorefractive keratectomy (PRK) for low myopia compared to high myopia and (2) there are both qualitative and quantitative differences in the cellular responses in the corneal stroma after PRK for high myopia and laser in situ keratomileusis (LASIK) for high myopia. METHODS: PRK for low myopia (-4.5 diopters [D]), PRK for high myopia (-9.0 D), and LASIK for high ...

  19. A prospective, contralateral comparison of photorefractive keratectomy (PRK) versus thin-flap LASIK: assessment of visual function

    OpenAIRE

    Hatch, Bryndon B; Moshirfar, Majid; Ollerton, Andrew J; Sikder, Shameema; Mifflin, Mark D.

    2011-01-01

    Purpose: To compare differences in visual acuity, contrast sensitivity, complications, and higher-order ocular aberrations (HOAs) in eyes with stable myopia undergoing either photo-refractive keratectomy (PRK) or thin-flap laser in situ keratomileusis (LASIK) (intended flap thickness of 90 μm) using the VISX Star S4 CustomVue excimer laser and the IntraLase FS60 femtosecond laser at 1, 3, and 6 months postoperatively. Methods: In this prospective, masked, and randomized pilot study, refractiv...

  20. A prospective, contralateral comparison of photorefractive keratectomy (PRK) versus thin-flap LASIK: assessment of visual function

    OpenAIRE

    Moshirfar, Majid

    2011-01-01

    Bryndon B Hatch1, Majid Moshirfar1, Andrew J Ollerton1, Shameema Sikder2, Mark D Mifflin11John A. Moran Eye Center, University of Utah, Salt Lake City, UT, USA; 2Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, USAPurpose: To compare differences in visual acuity, contrast sensitivity, complications, and higher-order ocular aberrations (HOAs) in eyes with stable myopia undergoing either photorefractive keratectomy (PRK) or thin-flap laser in situ keratomileusis (LASIK) (intended ...

  1. Laser-Assisted Subepithelial Keratectomy versus Laser In Situ Keratomileusis in Myopia: A Systematic Review and Meta-Analysis

    OpenAIRE

    Li-Quan Zhao; Huang Zhu; Liang-Mao Li

    2014-01-01

    This systematic review was to compare the clinical outcomes between laser-assisted subepithelial keratectomy (LASEK) and laser in situ keratomileusis (LASIK) for myopia. Primary parameters included mean manifest refraction spherical equivalent (MRSE), MRSE within ±0.50 diopters, uncorrected visual acuity (UCVA) ≥20/20, and loss of ≥1 line of best-corrected visual acuity (BCVA). Secondary parameters included flap complications and corneal haze. Twelve clinical controlled trials were identified...

  2. Efficacy, predictability, and safety of laser-assisted subepithelial keratectomy for the treatment of myopia and myopic astigmatism

    OpenAIRE

    Al-Tobaigy, Faisal M.

    2012-01-01

    Purpose: The purpose was to report the refractive and visual outcomes of laser-assisted subepithelial keratectomy (LASEK) for the treatment of myopia. Materials and Methods: A retrospective, noncomparative consecutive case series of 173 of 91 patients who had undergone LASEK is presented. Primary outcome variables included uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), manifest refraction, epithelialization time, pain, haze, and complications. Result...

  3. Overview of current chelation practices

    OpenAIRE

    Aydinok, Y.

    2011-01-01

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

  4. Bifunctional Chelates for Metal Nuclides

    OpenAIRE

    Brechbiel, Martin W.

    2007-01-01

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

  5. Alarming use of chelation therapy

    OpenAIRE

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

    2014-01-01

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

  6. Results of photorefractive keratectomy with mitomycin C for high myopia after 4 years

    Directory of Open Access Journals (Sweden)

    Farhad Fazel

    2008-04-01

    Full Text Available

    • BACKGROUND: This study assessed the long-term results of photorefractive keratectomy (PRK with mitomycin C in high myopia (.7 diopter.
    • METHODS: In this retrospective study, visual acuity, refractive error, pachymetry, topography, contrast sensitivity, corneal haze safety, predictability and complications (with emphasis on ectasia of 37 high myopic patients (72 eyes who had PRK surgery with mitomycin C in the last 10 to 40 months were assessed. The exclusion criteria included previous ocular surgery other than LASIK, current ocular disease and any systemic illness.
    • RESULTS: The mean follow up period was 27.2 ± 7.9 months. The spherical equivalent error was significantly reduced, from a mean of -9.10 ± 2.12 diopters (D (range of -7 to -18.25 D before PRK to a mean of -1.81 ± 1.57 D (range of - 8.5 to 0 D after (P = 0.001. Postoperatively, 34.72% of eyes were within ± 0.5 D of attempted correction and 58.33% within ±1 D and 84.72% within ±2 D. 80.5% of eyes had a vision of 20/40 or better. Best corrected visual acuity (BCVA was unchanged or improved in 93.05%. The safety index was 0.96 [the ratio of mean postoperative BCVA (0.84 to mean preoperative BCVA (0.87] and efficacy index was 0.8 [the ratio of mean postoperative uncorrected visual acuity (0.7 to mean preoperative BCVA (0.87]. Corneal haze formation was seen in 5 patients (6.9% with grade +1. The minimum stromal residual bed was 400 Cm. No eyes had progressive corneal ectasias at the time of post-op control.
    • CONCLUSIONS: The topical intraoperative application of 0.02% mitomycin C can reduce haze formation in highly myopic eyes undergoing PRK. Predictability of refractive results, however, was poor.
    • KEY WORDS: Mitomycin C, photorefractive keratectomy, high myopia.

  7. Ceratectomia fotorrefrativa baseada em topografia para correção da hipermetropia secundária à ceratotomia radial Topographically-guided photorefractive keratectomy for the management of secondary hyperopia following radial keratectomy

    Directory of Open Access Journals (Sweden)

    Vinícius Coral Ghanem

    2007-10-01

    Full Text Available OBJETIVO: Descrever nova técnica de ceratectomia fotorrefrativa baseada em topografia para correção da hipermetropia secundária à ceratotomia radial. MÉTODOS: Estudo retrospectivo realizado em pacientes submetidos a ceratectomia fotorrefrativa baseada em topografia para a correção da hipermetropia secundária à ceratotomia radial. Os pacientes apresentavam, no mínimo, 3 dioptrias de hipermetropia no pré-operatório, e apresentavam acompanhamento mínimo de 3 meses. RESULTADOS: Neste estudo foram avaliados 24 olhos de 21 pacientes com idade entre 36 e 55 anos (média de 45,54 ± 6,03 anos. O período médio de acompanhamento foi de 7,71 ± 4,6 meses (variando de 3 a 17 meses. A média do EE no pré-operatório foi de +3.92 ± 1.57, com variação de +1,25 D a +7,75 D e após a ablação, a média foi -0,29 ± 1,43 variando de 3,75 D a +2,50 D (pPURPOSE: To describe a topographically guided photorefractive keratectomy technique for the management of secon dary hyperopia following radial keratectomy. METHODS: A retrospective study was carried out in patients where a topographically guided photorefractive keratectomy technique was performed for the management of secondary hyperopia following radial keratectomy. The patients had preoperatively at least 3 diopters of hyperopia. The minimum follow-up was 3 months. RESULTS: Twenty-four eyes of 21 patients were evaluated. The mean age was 45.54 ± 6.03 years (range 36 to 55 years. The average follow-up was 7.71 ± 4.6 months (range 3 to 17 months. Preoperatively the average spherical equivalent was +3.92 ± 1.57 (range +1.25 D to +7.75 D, and postoperatively it was -0.29 ± 1.43 (range -3.75 D to +2.50 D (p<0.01. Visual acuity of 20/25 or better was achieved in 45.83% of the eyes, 20/40 or better in 83.33% and 20/60 or better in 100%. All patients were satisfied with the results and stated subjective improvement in visual quality. CONCLUSION: Considering that it is a retreatment procedure

  8. 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

  9. Effect of Homoharringtonine on Corneal Haze after Excimer Laser Photorefractive Keratectomy in Rabbits

    Institute of Scientific and Technical Information of China (English)

    ZHANG Mingchang; WANG Li; WANG Yong; DING Zhengping; MAI Caikeng; NIE Shaosong; CHEN Fei

    2005-01-01

    To evaluate the inhibiting effect of Homoharringtonine HHT) on the corneal haze after excimer laser photorefractive keratectomy (PRK) in rabbits. 18 healthy rabbits which underwent PRK were randomly divided into three groups (A, B and C). The refractive degree of ablation was -10. 0DS in each group. Group A was locally treated with a piece of filter paper soaked with 1 mg/mi HHT for 5 min, and then the entire cornea was repeatedly irrigated with balance solution;Group B was dropped with 0.1 mg/mL HHT after PRK for 3 months; Group C was the control group. Corneal haze, histopathology, response, ect. were investigated. The corneal haze was sig nificantly less in group A, while the difference between group B and group C was insignificant.Keratocytes and fibrocytes in corneal stroma were more active up to 3 months in group B and group C. Intraoperative use of topical HHT can reduce corneal haze after PRK in rabbits.

  10. Bilateral myopic photorefractive keratectomy in a 14-year-old boy

    Directory of Open Access Journals (Sweden)

    Italo Giuffrè

    2010-01-01

    Full Text Available Context: Refractive surgery has been performed for more than 10 years. Laser-assisted intrastromal keratomileusis (LASIK and photorefractive keratectomy (PRK may be used in accommodative esotropia either in adolescent or in adult patients. Some authors have shown that LASIK is safe, effective, and stable at 10 years follow-up post-surgery. Case report: A 14-year-old boy was admitted to our outpatient department on 08-01-2008. Together with his parents he asked for both eyes to be operated on by myopic PRK. On September 5 th 2008 a myopic PRK was performed on his right eye and on September 12 th 2008 on his left eye. A Bausch & Lomb Z172 excimer laser was used to perform a Planoscan procedure on both eyes. Uncorrected visual acuity was 1.0 after both procedures. The patient did not suffer pain, haze or glare in postoperative follow-up. Conclusion: Apart from the surgical technique, the author raises questions about the ethics of this procedure in a young boy.

  11. Bilateral myopic photorefractive keratectomy in a 14-year-old boy

    Directory of Open Access Journals (Sweden)

    Italo Giuffrè

    2010-01-01

    Full Text Available Context: Refractive surgery has been performed for more than 10 years. Laser-assisted intrastromal keratomileusis (LASIK and photorefractive keratectomy (PRK may be used in accommodative esotropia either in adolescent or in adult patients. Some authors have shown that LASIK is safe, effective, and stable at 10 years follow-up post-surgery. Case report: A 14-year-old boy was admitted to our outpatient department on 08-01-2008. Together with his parents he asked for both eyes to be operated on by myopic PRK. On September 5th 2008 a myopic PRK was performed on his right eye and on September 12th 2008 on his left eye. A Bausch & Lomb Z172 excimer laser was used to perform a Planoscan procedure on both eyes. Uncorrected visual acuity was 1.0 after both procedures. The patient did not suffer pain, haze or glare in postoperative follow-up. Conclusion: Apart from the surgical technique, the author raises questions about the ethics of this procedure in a young boy.

  12. Iron chelation and multiple sclerosis

    Directory of Open Access Journals (Sweden)

    Kelsey J. Weigel

    2014-01-01

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

  13. Luminescent lanthanide chelates and methods of use

    Energy Technology Data Exchange (ETDEWEB)

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

    1997-01-01

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

  14. Iron chelation and multiple sclerosis

    OpenAIRE

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

    2014-01-01

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

  15. Some Linguistic Detail on Chelation

    Science.gov (United States)

    Haworth, Daniel T.

    1998-01-01

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

  16. Photorefractive keratectomy in mild to moderate keratoconus: Outcomes in over 40-year-old patients

    Directory of Open Access Journals (Sweden)

    Hamid Khakshoor

    2015-01-01

    Full Text Available Background: Keratoconus is a contraindication for photorefractive keratectomy (PRK. In the recent decade, some efforts have been made to perform PRK in patients with keratoconus whose corneas are stable naturally or by doing corneal collagen crosslinking. These studies have suggested residual central corneal thickness (CCT ≥450 μm. Aims: The aim was to evaluate the long-term outcomes of PRK in patients with mild to moderate keratoconus in patients older than 40 with residual CCT ≥ 400 μm. Settings and Design: This prospective study was conducted in our Cornea Research Center, Mashhad, Iran. Materials and Methods: Patients over 40 years old, with a grade I/II keratoconus without progression in the last 2 years were recruited. Patients with a predicted postoperative CCT < 400 μm were excluded. PRK with tissue saving protocol was performed with Tecnolas 217 Z. Mitomycin-C was applied after ablation. The final endpoints were refraction parameters the last follow-up visit (mean: 35 months. Paired t-test and Chi-square were used for analysis. Results: A total of 38 eyes of 21 patients were studied; 20 eyes (52.6% with a grade I and 18 eyes (47.4% with grade II keratoconus. The mean uncorrected visual acuity, best corrected visual acuity (BCVA, spherical equivalent, cylindrical power and keratometric readings were significantly improved at the final endpoint compared to preoperation measurements (P < 0.001. Two eyes (5% lost two lines of BCVA at the final visit. No case of ectasia occurred during the follow-up course. Conclusions: PRK did not induce keratoconus progression in patients older than 40 with a grade I/II keratoconus. Residual CCT ≥ 450 μm seems to be sufficient to prevent the ectasia.

  17. Risk factors of regression and undercorrection in photorefractive keratectomy:a case-control study

    Directory of Open Access Journals (Sweden)

    Seyed-Farzad Mohammadi

    2015-10-01

    Full Text Available AIM:To determine risk factors of regression and undercorrection following photorefractive keratectomy (PRK in myopia or myopic astigmatism.METHODS: A case-control study was designed in which eyes with an indication for re-treatment (RT were defined as cases; primary criteria for RT indication, as assessed at least 9mo postoperatively, included an uncorrected distance visual acuity (UDVA of 20/30 or worse and a stable refraction for more than 3mo. Additional considerations included optical quality symptoms and significant higher order aberrations (HOAs. Controls were chosen from the same cohort of operated eyes which had complete post-operative follow up data beyond 9mo and did not need RT. The cohort included patients who had undergone PRK by the Tissue-Saving (TS ablation profile of Technolas 217z100 excimer laser (Bausch & Lomb, Rochester, NY, USA. Mitomycin C had been used in all of the primary procedures.RESULTS:We had 70 case eyes and 158 control eyes, and they were comparable in terms of age, sex and follow-up time (P values:0.58, 1.00 and 0.89, respectively. Pre-operative spherical equivalent of more than -5.00 diopter (D, intended optical zone (OZ diameter of less than 6.00 mm and ocular fixation instability during laser ablation were associated with RT indications (all P values <0.001. These factors maintained their significance in the multiple logistic regression model with odd ratios of 6.12, 6.71 and 7.89, respectively.CONCLUSION:Higher refractive correction (>-5.00 D, smaller OZ (<6.00 mm and unstable fixation during laser ablation of PRK for myopia and myopic astigmatism were found to be strong predictors of undercorrection and regression.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-07-01

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

  19. Status of chelation research: a review

    International Nuclear Information System (INIS)

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

  20. Iron Chelation Therapy in Myelodysplastic Syndromes

    OpenAIRE

    Giuseppe Saglio; Daniela Cilloni; Emanuela Messa

    2010-01-01

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

  1. Beliefs about chelation among thalassemia patients

    OpenAIRE

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

    2012-01-01

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

  2. Role of chelates in treatment of cancer

    Directory of Open Access Journals (Sweden)

    Tripathi Laxmi

    2007-01-01

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

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

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

    Budimir, Ana

    2011-03-01

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

  5. Importance of iron chelation therapy

    OpenAIRE

    A. Varoğlu

    2011-01-01

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

  6. Factors Affecting Long-term Myopic Regression after Laser In Situ Keratomileusis and Laser-assisted Subepithelial Keratectomy for Moderate Myopia

    OpenAIRE

    Lim, Sung A; Park, Yooyeon; Cheong, Yu Jin; Na, Kyung Sun; Joo, Choun-Ki

    2016-01-01

    Purpose High myopia is known to be a risk factor for long-term regression after laser refractive surgery. There have been few studies about the correction of moderate myopias that did not need retreatment after long-term follow-up. We evaluated 10 years of change in visual acuity and refractive power in eyes with moderate myopia after laser refractive surgery. Methods We included patients that had undergone laser in situ keratomileusis (LASIK) or laser-assisted subepithelial keratectomy (LASE...

  7. COMPARISON OF LASER IN SITU KERATOMILEUSIS (LASIK AND PHOTOREFRACTIVE KERATECTOMY (PRK IN CORRECTING LOW TO MODERATE MYOPIA WITH OR WITHOUT ASTIGMATISM

    Directory of Open Access Journals (Sweden)

    Mostafa A. El-Husseiny

    2014-05-01

    Full Text Available Purpose: To compare refractive and visual outcomes in patients treated with Photorefractive keratectomy (PRK and laser in situ keratomileusis (LASIK in cases of mild to moderate myopia with or without astigmatism in a prospective randomized clinical trial. Setting: Research Institute of Ophthalmology (RIO and RCC refractive center, Giza, Egypt. Methods: Refractive and visual acuity results in a cohort of 80 eyes of 40 consecutive patients were randomized to receive either PRK or LASIK by the first two surgeons.

  8. COMPARISON OF LASER IN SITU KERATOMILEUSIS (LASIK) AND PHOTOREFRACTIVE KERATECTOMY (PRK) IN CORRECTING LOW TO MODERATE MYOPIA WITH OR WITHOUT ASTIGMATISM

    OpenAIRE

    Mostafa A. El-Husseiny; Olfat A. Hassanin; Iman M. Eissa a; Mohamed Yasser Farag

    2014-01-01

    Purpose: To compare refractive and visual outcomes in patients treated with Photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) in cases of mild to moderate myopia with or without astigmatism in a prospective randomized clinical trial. Setting: Research Institute of Ophthalmology (RIO) and RCC refractive center, Giza, Egypt. Methods: Refractive and visual acuity results in a cohort of 80 eyes of 40 consecutive patients were randomized to receive either P...

  9. Central Corneal Thickness in Highly Myopic Eyes: Inter-device Agreement of Ultrasonic Pachymetry, Pentacam and Orbscan II Before and After Photorefractive Keratectomy

    OpenAIRE

    Nader Nassiri; Kourosh Sheibani; Sare Safi; Saman Nassiri; Alireza Ziaei; Farnaz Haji; Shiva Mehravaran; Nariman Nassiri

    2014-01-01

    Purpose: To determine inter-device agreement for central corneal thickness (CCT) measurement among ultrasound pachymetry, rotating Scheimpflug imaging (Pentacam, Oculus, Wetzlar, Germany), and scanning slit corneal topography (Orbscan II, Bausch & Lomb, Rochester, NY, USA) in highly myopic eyes before and after photorefractive keratectomy (PRK). Methods: This prospective comparative study included 61 eyes of 32 patients with high myopia who underwent PRK. Six month postoperative CCT value...

  10. Chelating agents in pharmacology, toxicology and therapeutics

    International Nuclear Information System (INIS)

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

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

    OpenAIRE

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

    2014-01-01

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

  12. 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.

  13. A prospective, contralateral comparison of photorefractive keratectomy (PRK versus thin-flap LASIK: assessment of visual function

    Directory of Open Access Journals (Sweden)

    Hatch BB

    2011-04-01

    Full Text Available Bryndon B Hatch1, Majid Moshirfar1, Andrew J Ollerton1, Shameema Sikder2, Mark D Mifflin11John A. Moran Eye Center, University of Utah, Salt Lake City, UT, USA; 2Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, USAPurpose: To compare differences in visual acuity, contrast sensitivity, complications, and higher-order ocular aberrations (HOAs in eyes with stable myopia undergoing either photorefractive keratectomy (PRK or thin-flap laser in situ keratomileusis (LASIK (intended flap thickness of 90 µm using the VISX Star S4 CustomVue excimer laser and the IntraLase FS60 femtosecond laser at 1, 3, and 6 months postoperatively.Methods: In this prospective, masked, and randomized pilot study, refractive surgery was performed contralaterally on 52 eyes: 26 with PRK and 26 with thin-flap LASIK. Primary outcome measures were uncorrected distance visual acuity (UDVA, corrected distance visual acuity (CDVA, contrast sensitivity, and complications.Results: At 6 months, mean values for UDVA (logMAR were -0.043 ± 0.668 and -0.061 ± 0.099 in the PRK and thin-flap LASIK groups, respectively (n = 25, P = 0.466. UDVA of 20/20 or better was achieved in 96% of eyes undergoing PRK and 92% of eyes undergoing thin-flap LASIK, whereas 20/15 vision or better was achieved in 73% of eyes undergoing PRK and 72% of eyes undergoing thin-flap LASIK (P > 0.600. Significant differences were not found between treatment groups in contrast sensitivity (P ≥ 0.156 or CDVA (P = 0.800 at postoperative 6 months. Types of complications differed between groups, notably 35% of eyes in the thin-flap LASIK group experiencing complications, including microstriae and 2 flap tears.Conclusion: Under well-controlled surgical conditions, PRK and thin-flap LASIK refractive surgeries achieve similar results in visual acuity, contrast sensitivity, and induction of HOAs, with differences in experienced complications.Keywords: photorefractive keratectomy, thin-flap LASIK, visual

  14. Prophylactic Effects of Mitomycin-C on Regression and Haze Formation in Photorefractive Keratectomy

    Directory of Open Access Journals (Sweden)

    Hassan Hashemi

    2008-12-01

    Full Text Available

    PURPOSE: To study the effect of prophylactic application of mitomycin-C on regression and corneal haze formation after photorefractive keratectomy (PRK for high myopia. METHODS: Fifty-four eyes of 28 high myopic patients were enrolled in this prospective study. All eyes underwent PRK with application of 0.02% mitomycin-C for two minutes and irrigation with 15-20 ml of normal saline. Follow-up visits were scheduled for the first 7 days and 1, 3 and 6 months after surgery. Hanna grading (in the scale of 0 to 4+ was used to assess corneal haze. RESULTS: Mean spherical equivalent refraction (SE was -7.08 ± 1.11 diopters (D, preoperatively. All eyes were examined on the first 7 days and one month after surgery; 48 eyes (88.9% were evaluated 3 and 6 months post-surgery. Six months after surgery, all eyes had uncorrected visual acuity (UCVA of 20/40 or better and 37 eyes (77.1 % achieved UCVA of 20/20 or better, 45 eyes (93.7% had SE within ±1.00D of emmetropia. One month postoperatively, 2 eyes (3.7% had grade 0.5 haze, while at 3 and 6 months after surgery no visited eye had haze at all. There was no decrease in best corrected visual acuity after 6 months. In spatial frequencies of 6 and 12 cycle/degree, contrast sensitivity decreased immediately after PRK but increased to the preoperative values by the 6th postoperative month

  15. Photorefractive keratectomy for correction of myopia: Our one-year experience

    Directory of Open Access Journals (Sweden)

    Resan Mirko

    2012-01-01

    Full Text Available Background/Aim. Photorefractive keratectomy (PRK, after laser in situ keratomileusis (LASIK, is commonly performed refractive surgical method worldwide. The aim of this study was to examine the effectiveness and safety of PRK in correction of various strengths of myopia and to assess how much corneal tissue is being removed with one diopter sphere (Dsph correction by using different optical zones (OZ. Methods. A prospective study with a follow-up period of 6 months included 55 patients of which 100 myopic eyes were treated by PRK method (one eye was included in 10 patients. Myopic eyes with a preoperative best corrected visual acuity (BCVA = 1.0 (20/20 were analysed. In order to assess the effectiveness of PRK operated myopic eyes were divided into four groups according to the dioptric power: 1≤ -1.75 Dsph (n = 26; 2 from -2 to -3.75 Dsph (n = 44; 3 from -4 to -6.75 Dsph (n = 23, and 4 ≥ -7 Dsph (n = 7. Myopic eyes with preoperative BCVA ≤ 0.9 (amblyopic eyes were excluded from the study, as well as eyes with astigmatism > -1.5 Dcyl. To assess the effectiveness of PRK we examined the percentage of eyes in the mentioned groups, which derived uncorrected visual acuity (UCVA 6 months after the intervention to the following: a UCVA = 1.0 (20/20 and b UCVA ≥ 0.5 (20/40. To assess the safety of PRK we examined the frequency of intraoperative and postoperative complications. To estimate how much corneal tissue was removed with one Dsph correction by using different OZ, we used preoperative and postoperative (after 6 months central pachymetry values expressed in μm and volume of cornea (central 7 mm expressed in mm³. In that sense, we used only the myopic eyes with clear preoperative spherical refraction. The total number of these eyes was 27, of which 16 eyes were treated using a 6.5 mm OZ and 11 eyes using a 7 mm OZ. Results. Refractive spherical equivalent (RSE for all eyes was in the range from -0.75 to -8.75 Dsph, and preoperative mean

  16. Current Use of Chelation in American Health Care

    OpenAIRE

    Wax, Paul M.

    2013-01-01

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

  17. Effect of excimer laser (Arf, 193 nm) on aqueous humor during photorefractive keratectomy biophysical and biochemical study

    International Nuclear Information System (INIS)

    Ultraviolet light (193 nm) produced by an excimer laser has been used to produce precise tissue ablation with minimal thermal damage to adjacent tissue. The present study was designed to investigate the effect of excimer laser during photo refractive keratectomy (PRK) on aqueous humor constituents and also the effect of antioxidant enzyme superoxide dismutase (SOD)- applied topically- on these changes if exist. Five groups of schenchilla rabbits were involved in this study, where four groups underwent corneal stromal ablation using argon fluoride excimer laser (Ar F, 193 nm). Two of these four groups were treated with superoxide dismutase intra operatively. The fifth group was used as control one. The obtained results revealed depletion of aqueous humor ascorbate and glutathione contents. Aqueous humor refractive index, cholesterol, phospholipids, malondialdehyde (MDA) and total protein were measured. In conclusion, the excimer laser can induce changes in aqueous humor constituents during PRK. These changes lasted at least for 24 hours and as the time increased to 4 weeks, these changes became limited. The use of exogenous SOD seems to exert beneficial effect on aqueous humor refractive index and total protein

  18. Multiple limbal haemangiosarcomas in a border collie dog: management by lamellar keratectomy/sclerectomy and strontium-90 beta plesiotherapy.

    Science.gov (United States)

    Donaldson, D; Sansom, J; Murphy, S; Scase, T

    2006-09-01

    An eight-year-old, neutered, male border collie dog was presented with a six-week history of left ocular discomfort and a raised, red mass at the lateral limbus. The right eye had been enucleated approximately 12 months previously following suspected trauma when the eye had become red and painful. The mass was excised using superficial keratectomy/sclerectomy and the surgery site was treated with strontium-90 beta radiation. Histopathological findings were consistent with a diagnosis of haemangiosarcoma. Immunohistochemical staining showed uniform expression of CD31 in neoplastic cells, confirming their endothelial origin. Two further treatments with strontium-90 beta radiation were applied to the surgical site at weekly intervals. Twenty-six weeks after surgery, a second, raised, red limbal mass became apparent at the medial limbus of the left eye. Surgical excision and adjuvant strontium-90 beta plesiotherapy were performed as described for the initial tumour. Routine histopathological analysis confirmed haemangiosarcoma at this site. Eighty-six weeks following the initial presentation, no recurrence of ocular haemangiosarcoma was evident. PMID:16961474

  19. Copper Chelation in Alzheimer's Disease Protein

    Science.gov (United States)

    Rose, Frisco; Hodak, Miroslav; Bernholc, Jerry

    2013-03-01

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

  20. Optimisation and status of chelation therapy

    International Nuclear Information System (INIS)

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

  1. Lanthanon chelates of monoprotic tridentate schiff base

    International Nuclear Information System (INIS)

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

  2. Trypanotoxic activity of thiosemicarbazone iron chelators.

    Science.gov (United States)

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

    2015-03-01

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

  3. Recent developments centered on orally active iron chelators

    Directory of Open Access Journals (Sweden)

    Robert Hider

    2014-09-01

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

  4. Development of an upconverting chelate assay

    Science.gov (United States)

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

    2005-04-01

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

  5. Questions and Answers on Unapproved Chelation Products

    Science.gov (United States)

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

  6. Military target task performance after wavefront-guided (WFG) and wavefront-optimized (WFO) photorefractive keratectomy (PRK)

    Science.gov (United States)

    Maurer, Tana; Deaver, Dawne; Howell, Christopher; Moyer, Steve; Nguyen, Oanh; Mueller, Greg; Ryan, Denise; Sia, Rose K.; Stutzman, Richard; Pasternak, Joseph; Bower, Kraig

    2014-06-01

    Major decisions regarding life and death are routinely made on the modern battlefield, where visual function of the individual soldier can be of critical importance in the decision-making process. Glasses in the combat environment have considerable disadvantages: degradation of short term visual performance can occur as dust and sweat accumulate on lenses during a mission or patrol; long term visual performance can diminish as lenses become increasingly scratched and pitted; during periods of intense physical trauma, glasses can be knocked off the soldier's face and lost or broken. Although refractive surgery offers certain benefits on the battlefield when compared to wearing glasses, it is not without potential disadvantages. As a byproduct of refractive surgery, elevated optical aberrations can be induced, causing decreases in contrast sensitivity and increases in the symptoms of glare, halos, and starbursts. Typically, these symptoms occur under low light level conditions, the same conditions under which most military operations are initiated. With the advent of wavefront aberrometry, we are now seeing correction not only of myopia and astigmatism but of other, smaller optical aberrations that can cause the above symptoms. In collaboration with the Warfighter Refractive Eye Surgery Program and Research Center (WRESP-RC) at Fort Belvoir and Walter Reed National Military Medical Center (WRNMMC), the overall objective of this study is to determine the impact of wavefront guided (WFG) versus wavefront-optimized (WFO) photorefractive keratectomy (PRK) on military task visual performance. Psychophysical perception testing was conducted before and after surgery to measure each participant's performance regarding target detection and identification using thermal imagery. The results are presented here.

  7. Epipolis-laser in situ keratomileusis versus photorefractive keratectomy for the correction of myopia: a meta-analysis.

    Science.gov (United States)

    Wu, Wenjing; Wang, Yan; Xu, Lulu

    2015-10-01

    It is unclear whether epipolis-laser in situ keratomileusis (Epi-LASIK) has any significant advantage over photorefractive keratectomy (PRK) for correcting myopia. We undertook this meta-analysis of randomized controlled trials and cohort studies to examine possible differences in efficacy, predictability, and side effects between Epi-LASIK and PRK for correcting myopia. A system literature review was conducted in the PubMed, Cochrane Library EMBASE. The statistical analysis was performed by RevMan 5.0 software. The results included efficacy outcomes (percentage of eyes with 20/20 uncorrected visual acuity post-treatment), predictability (proportion of eyes within ±0.5 D of the target refraction), epithelial healing time, and the incidence of significant haze and pain scores after surgery. There are seven articles with total 987 eyes suitable for the meta-analysis. There is no statistical significance in the predictability between Epi-LASIK and PRK, the risk ratio (RR) is 1.03, 95% confidence interval (CI) [0.92, 1.16], p = 0.18; with respect to efficacy, the odds ratio is 1.43, 95% CI = [0.85, 2.40], p = 0.56 between Epi-LASIK and PRK, there is no statistical significance either. The epithelial cell layer healing time and the pain scores and the incidence of significant haze showed no significance between these two techniques although more pains can be found in Epi-LASIK than PRK at the early-stage post-operation. According to the above analysis, Epi-LASIK has good efficacy and predictability as PRK. In addition, both techniques have low pain scores and low incidence of significant haze. PMID:26253460

  8. Topography and raytracing analysis of patients with excellent visual acuity 3 months after excimer laser photorefractive keratectomy for myopia.

    Science.gov (United States)

    Maguire, L J; Zabel, R W; Parker, P; Lindstrom, R L

    1991-01-01

    We performed topography and raytracing analysis 3 months after surgery on five consecutive eyes of five patients, which had excimer laser photorefractive keratectomy for myopia. Three of the five eyes had uncorrected postoperative visual acuity of 20/20 or better. Two eyes had an uncorrected vision of 20/40. In three of five eyes, the area of excimer ablation was centered within 1.0 mm of the optical axis. Three other eyes showed decentration that ranged from 1.1 to 1.5 mm. The range of surface power seen within 2 mm of the central keratoscope ring was as follows: patient CK = 37.50 to 39.50 diopters; patient CA = 40.50 D to 44.80 D; patient CW = 37.90 D to 42.20 D; patient AC = 35.50 D to 39.00 D; patient DT = 34.50 D to 41.40 D. Topography patterns differed from eye to eye. A raytracing program modeled refraction of 20/80 and 20/20 "E" of 100%, 50%, 25%, 12.5% and 6.25% contrast through all measured points on the central 10 keratoscope rings of the five postoperative corneas. The five computer-derived images were ranked subjectively according to the observed degree of image degradation by three observers. Two eyes showed discernible 20/20 E's even at the 12.5% contrast level. Little to no ghost image was seen. Two eyes showed degraded but discernible 20/20 letters at higher levels of contrast only. These eyes showed moderate ghost images that were most apparent in the high-contrast 20/80 letters. One eye showed poor resolution of the 100% contrast 20/20 letter and moderately severe ghost images.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2043557

  9. Efficacy, predictability, and safety of laser-assisted subepithelial keratectomy for the treatment of myopia and myopic astigmatism

    Directory of Open Access Journals (Sweden)

    Faisal M Al-Tobaigy

    2012-01-01

    Full Text Available Purpose: The purpose was to report the refractive and visual outcomes of laser-assisted subepithelial keratectomy (LASEK for the treatment of myopia. Materials and Methods: A retrospective, noncomparative consecutive case series of 173 of 91 patients who had undergone LASEK is presented. Primary outcome variables included uncorrected visual acuity (UCVA, best spectacle-corrected visual acuity (BSCVA, manifest refraction, epithelialization time, pain, haze, and complications. Results: Preoperatively, the mean spherical equivalent (SE was −3.71 ± 1.63 D (range, −0.875 D to 8.25 D, and the mean LogMAR BSCVA was −0.0374 ± 0.0767 D (range, −0.47 D to 0.00 D. On the final visit, the mean SE was −0.05 ± 0.335 D (range, −1.63 D to 1.00 D, the mean LogMAR UCVA was 0.04674 ± 0.0771 D (range, −0.3010 D to 0.1249 D and the mean LogMAR BSCVA was −0.0164 ± 0.0497 (range −0.3010 to 0.124. All eyes achieved vision of 20/40 or better, and 83.2% of the eyes achieved a vision of 20/25 or better. One 64 (94.94% and all the eyes were within ± 0.50 D and ± 1.00 D of the attempted correction respectively. Complete epithelialization occurred in 4.70 ± 2.09 days (range, 2-10 days. At the final visit, 79.7% of eyes had a clear cornea. Grade 1 haze developed in 17.34% of the eyes, grade 2 haze developed in 2.89% of eyes developed; no eyes developed grade 3 or 4 haze. Conclusions: LASEK is a safe, effective, and predictable method for the treatment of myopia and myopic astigmatism.

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

    OpenAIRE

    Banu Kaya

    2014-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Banu Kaya

    2014-12-01

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

  12. Wavefront-Guided Photorefractive Keratectomy with the Use of a New Hartmann-Shack Aberrometer in Patients with Myopia and Compound Myopic Astigmatism

    Directory of Open Access Journals (Sweden)

    Steven C. Schallhorn

    2015-01-01

    Full Text Available Purpose. To assess refractive and visual outcomes and patient satisfaction of wavefront-guided photorefractive keratectomy (PRK in eyes with myopia and compound myopic astigmatism, with the ablation profile derived from a new Hartmann-Shack aberrometer. Methods. In this retrospective study, 662 eyes that underwent wavefront-guided PRK with a treatment profile derived from a new generation Hartmann-Shack aberrometer (iDesign aberrometer, Abbott Medical Optics, Inc., Santa Ana, CA were analyzed. The preoperative manifest sphere ranged from −0.25 to −10.75 D, and preoperative manifest cylinder was between 0.00 and −5.25 D. Refractive and visual outcomes, vector analysis of the change in refractive cylinder, and patient satisfaction were evaluated. Results. At 3 months, 91.1% of eyes had manifest spherical equivalent within 0.50 D. The percentage of eyes achieving uncorrected distance visual acuity 20/20 or better was 89.4% monocularly and 96.5% binocularly. The mean correction ratio of refractive cylinder was 1.02 ± 0.43, and the mean error of angle was 0.00 ± 14.86° at 3 months postoperatively. Self-reported scores for optical side effects, such as starburst, glare, halo, ghosting, and double vision, were low. Conclusion. The use of a new Hartmann-Shack aberrometer for wavefront-guided photorefractive keratectomy resulted in high predictability, efficacy, and patient satisfaction.

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

    OpenAIRE

    Ingale Satish Dinkarrao; Kankariya Rajendra

    2013-01-01

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

  14. Influence of Chelating Agents on Chromium Fate in Sediment

    Institute of Scientific and Technical Information of China (English)

    WANGXIAOCHANG; SUNJINHE; 等

    1996-01-01

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

  15. Pentaarylcyclopentadiene und chirale Ruthenium-Chelat-Komplexe

    OpenAIRE

    Kanthak, Matthias

    2010-01-01

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

  16. Federal Regulation of Unapproved Chelation Products

    OpenAIRE

    Lee, Charles E.

    2013-01-01

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

  17. EDTA: the chelating agent under environmental scrutiny

    OpenAIRE

    Claudia Oviedo; Jaime Rodríguez

    2003-01-01

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

  18. Conjugates of monoclonal antibodies and chelating polymers

    International Nuclear Information System (INIS)

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

  19. Decorporation of metal ions by chelating agents

    International Nuclear Information System (INIS)

    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)

  20. 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

  1. Comparison of single-step reverse transepithelial all-surface laser ablation (ASLA to alcohol-assisted photorefractive keratectomy

    Directory of Open Access Journals (Sweden)

    Aslanides IM

    2012-06-01

    Full Text Available Ioannis M Aslanides,1 Sara Padroni,1 Samuel Arba Mosquera,2 Antonis Ioannides,1 Achyut Mukherjee11Emmetropia Mediterranean Eye Institute, Heraklion, Crete, Greece; 2Schwind eye-tech-solutions GmbH, Kleinostheim, GermanyPurpose: To evaluate postoperative pain, corneal epithelial healing, development of corneal haze, refractive outcomes, and corneal aberrations in a novel one-step, modified transepithelial photorefractive keratectomy (PRK, termed All-surface laser ablation (ASLA, compared to conventional, alcohol-assisted PRK.Materials and methods: Sixty eyes of 30 myopic patients were prospectively recruited to a randomized fellow eye study. Patients underwent conventional alcohol-assisted PRK in one eye (control group and ASLA-modified transepithelial PRK in the other (30 eyes in each treatment arm. Primary endpoints were postoperative pain and haze scores at 1 day, 3 days, 1 week, and 1, 3, 6, and 12 months. Secondary endpoints included visual acuity at 1, 3, 6, and 12 months, corneal aberrations at 3, 6, and 12 months, and early and late onset haze. Refractive predictability, safety, and efficacy of the two methods were considered.Results: The average age of the cohort was 29 years (standard deviation [SD]: 9; range: 18–46, and the average spherical equivalent refractive error was -4.18 diopters (SD: 1.9. At 3 days after surgery, the average pain score was 64% lower in the ASLA group (P < 0.0005. At this point, 96% of ASLA eyes had no epithelial defect, whereas 43% in the alcohol-assisted group did not achieve complete epithelial healing, and required replacement of bandage contact lens. The haze level was consistently lower in the ASLA group at all time points from 1 to 6 months.Conclusion: This study shows that the ASLA technique may have a future role in refractive surgery, due to the fact that it offers faster epithelial healing, lower pain scores, and significantly less haze formation.Keywords: cornea, ASLA, PRK, alcohol

  2. Clinical assessment of frequency and structure of subepithelial fibroplasias of a cornea after a photorefractive keratectomy in patients with refraction anomalies

    Directory of Open Access Journals (Sweden)

    V. V. Egorov

    2014-07-01

    Full Text Available Purpose: To investigate the frequency and structure of a subepithelial fibroplasia of a cornea after photorefractive keratectomy concerning myopia correction.Methods: 170 patients (337 eyes with the following refraction anomalies: stationary myopia from 1.5 to 13.0 D with astigmatism from 0.75 to 4.25 D. Frequency of survey in the postoperative period — in 1, 3, 6, 12 months. To all patients Dexamethasone instillation according to the decreasing scheme was carried out. Existence of biomicroscopic signs of any degrees of subepithelial fibroplasias of a cornea, existence and extent of loss of uncorrected visual acuity in comparison with initial, regress of refractive effect of operation were taped. Subjective estimation of quality of vision was made by patients in 1 year after operations.Results: Subepithelial fibroplasias with intensity 1.0‑2.5 points stopped in whole or in part after additional treatment, were surveyed as clinically significant and made 4,75 % (16 eyes, 9 patients. Terms of their emergence: from 1 to 10 months after operation. At 3 patients (6 eyes intensity of fibroplasias made 2.0‑2.5 points before treatment and 1.0‑2.5 points after it. To the observation extremity 7 patients from this group had visual complaints, a discomfort in an eye. Indicators of Subjective estimation of quality of vision in patients with clinically significant fibroplasias of a cornea varied from 5 to 2.9 points.Conclusion: Frequency of clinically significant fibroplasias after photorefractive keratectomy made 4.75 %. After treatment theirintensity made 1.5‑2.5 points only in 4 eyes (2 patients.

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

    OpenAIRE

    ZviIoavCabantchik; ArnoldMunnich; MoussaB.Youdim; DavidDevos

    2013-01-01

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

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

    International Nuclear Information System (INIS)

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

  5. Trypanotoxic activity of thiosemicarbazone iron chelators

    OpenAIRE

    Ellis, Samuel; Sexton, Darren; Steverding, Dietmar

    2015-01-01

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

  6. Novel Terbium Chelate Doped Fluorescent Silica Nanoparticles

    Institute of Scientific and Technical Information of China (English)

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

    2006-01-01

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

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

    International Nuclear Information System (INIS)

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

  8. 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.

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

    Directory of Open Access Journals (Sweden)

    Ingale Satish Dinkarrao

    2013-06-01

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

  10. Decorporation of inhaled actinides by chelation therapy

    International Nuclear Information System (INIS)

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

  11. Chemical treatment of chelated metal finishing wastes.

    Science.gov (United States)

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

    2012-12-01

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

  12. 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…

  13. Macrocyclic Chelator Assembled RGD Multimers for Tumor Targeting

    OpenAIRE

    Zhang, Xiaofen; Liu, Hongguang; Miao, Zheng; Kimura, Richard; Fan, Feiyue; Cheng, Zhen

    2011-01-01

    Macrocyclic chelators have been extensively used for complexation of metal ions. A widely used chelator, DOTA, has been explored as a molecular platform to assemble multiple bioactive peptides in this paper. The multivalent DOTA-peptide bioconjugates demonstrate promising tumor targeting ability.

  14. Inapplicability of high pressure spray injection for chelate administration

    International Nuclear Information System (INIS)

    A high-pressure spray injector was tested for use in injecting chelating agents around radionuclides in wounds. It was difficult to employ because of the force required for proper injection, and it did not improve the effectiveness of the injected chelate in removing intramuscularly injected 238Pu. (U.S.)

  15. Adsorptive separation of rare earths by using chelating chitosan

    International Nuclear Information System (INIS)

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

  16. 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 lysi

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

    Directory of Open Access Journals (Sweden)

    Monika E. Miller

    2015-12-01

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

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

    International Nuclear Information System (INIS)

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

  19. New chelation strategies for the uranyl ion

    International Nuclear Information System (INIS)

    Traditional approaches to the design of metal-ion-specific complexing agents have relied to a great extent on the creation of a ligand cavity of the appropriate size and coordination number to accommodate the targeted metal ion. Oxo-metal ions, such as uranyl, cannot be dealt with as spherically symmetric charged atoms and thus present both a special challenge and offer a unique advantage for specific chelation in solution. To maximize recognition of the anisotropic UO22+ ion, new tripodal hexadentate ligands have been prepared providing three carboxyl moieties each to act as a bidentate donor group. The novel ligand design concept, ligand syntheses, and thermodynamic results related to the uranyl complex characterization are presented

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

    Science.gov (United States)

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

    2016-07-01

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

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

    International Nuclear Information System (INIS)

    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)

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

    Science.gov (United States)

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

    2013-10-01

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

  3. Selectivity in extraction of copper and indium with chelate extractants

    International Nuclear Information System (INIS)

    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 CuR2 and InR3 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)

  4. Screening wheat genotypes in response to ordinary chelate and nano-iron chelate fertilizers in nutrient solution

    OpenAIRE

    S. Omidi Nargesi; Zahedi, M; H.R. Eshghizadeh; A.H. Khoshgoftarmanesh

    2015-01-01

    Recently, attentions have been taken on the investigations regarding the use of nano-sized compounds in different fields including agricultural sector. Due to the importance of evaluating the fate and operation of nano-particles in plant systems, in this survey, responses of 13 wheat genotypes to the effect of nano-iron chelate fertilizer in the Hoagland solution under the conditions of ordinary iron chelate and nano-iron chelate, with concentration of 22.5 mg/L, was studied. This experiment ...

  5. Interface Keratitis due to Mycobacterium fortuitum following Laser In Situ Keratomileusis.

    OpenAIRE

    Fogla Rajesh; Rao Srinivas; Padmanabhan Prema

    2003-01-01

    A case of unilateral interface keratitis due to Mycobacterium fortuitum following simultaneous bilateral LASIK procedure for low myopia is reported. Excimer phototherapeutic keratectomy was performed to the stromal bed to reduce the infective load. Intensive topical therapy with topical amikacin and ciprofloxacin resulted in resolution of the keratitis.

  6. Interface Keratitis due to Mycobacterium fortuitum following Laser In Situ Keratomileusis.

    Directory of Open Access Journals (Sweden)

    Fogla Rajesh

    2003-01-01

    Full Text Available A case of unilateral interface keratitis due to Mycobacterium fortuitum following simultaneous bilateral LASIK procedure for low myopia is reported. Excimer phototherapeutic keratectomy was performed to the stromal bed to reduce the infective load. Intensive topical therapy with topical amikacin and ciprofloxacin resulted in resolution of the keratitis.

  7. Comparing the rate of regression after conductive keratoplasty with or without prior laser-assisted in situ keratomileusis or photorefractive keratectomy

    Directory of Open Access Journals (Sweden)

    Majid Moshirfar

    2012-01-01

    Full Text Available Purpose: To assess the regression rate of conductive keratoplasty (CK in patients with or without previous laser-assisted in situ keratomileusis (LASIK or photorefractive keratectomy (PRK. Setting: University of Utah, Medical School, John A. Moran Eye Center, Salt Lake City, Utah. Materials and Methods: A retrospective, age-matched chart review identified records of 6 patients who underwent CK after refractive surgery and 12 patients who underwent CK without prior refractive surgery. The main outcome measures were postoperative uncorrected and corrected visual acuities and refraction changes over time. Results: Preoperatively, the mean manifest refraction spherical equivalent (MRSE of the 15 eyes (12 patients that underwent CK without refractive surgery was 0.83 diopters (D and the 7 eyes (6 patients that underwent CK after refractive surgery had an average MRSE of 0.27 D. Postoperatively, the mean MRSE of the refractive surgery patients was -0.86 D at 6 months, regressing to -0.67 D at 12 months. The postoperative MRSE in the eyes without refractive surgery was -0.58 D. at 6 months, regressing to -0.38 D at 12 months. The rate of regression was linear in both groups, calculated at 0.033 D per month in all patients. Conclusions: Patients with previous LASIK or PRK showed a greater treatment response to CK but regressed at a similar rate as those eyes without prior LASIK or PRK. Overall CK is a safe procedure that inevitably regresses.

  8. Effect of the combination of basic fibroblast growth factor and cysteine on corneal epithelial healing after photorefractive keratectomy in patients affected by myopia

    Directory of Open Access Journals (Sweden)

    Alessandro Meduri

    2014-01-01

    Full Text Available Background: This study sought to evaluate the effect of basic fibroblast growth factor eye drops and cysteine oral supplements on corneal healing in patients treated with photorefractive keratectomy (PRK. Materials and Methods: One hundred and twenty patients treated bilaterally with PRK for myopia were enrolled at one of two eye centers (Clinica Santa Lucia, Bologna, Italy and Department of Ophthalmology, University of Magna Graecia, Catanzaro, Italy and were treated at the former center. Sixty patients included in the study group (Group 1 were treated postoperatively with topical basic fibroblast growth factor plus oral L-cysteine supplements, whereas 60 subjects included in the control group (Group 2 received basic fibroblast growth factor eye drops. We recorded the rate of corneal re-epithelialization and patients were followed-up every 30 days for 6 months. Statistical analyses were performed on the collected data. Results: The eyes in Group 1 demonstrated complete re-epithelialization at Day 5, whereas the eyes in Group 2 achieved this status on Day 6. No side-effects were reported. Conclusions : Patients treated with basic fibroblast growth factor eye drops and L-cysteine oral supplements benefit from more rapid corneal re-epithelialization. In human eyes, this combination treatment appeared to be safe and effective in accelerating corneal surfacing after surgery. Financial Disclosure: No author has any financial or proprietary interest in any material or method used in this study. Trial Registration: Current Controlled Trials ISRCTN73824458.

  9. Effects of macromolecular chelators on intestinal cadmium absorption in mice

    Energy Technology Data Exchange (ETDEWEB)

    Andersen, O.; Nielsen, J.B.; Bulman, R.A.

    1989-01-01

    Suppression of absorption by macromolecular chelators have been sucessful with several metals. In this paper a series of immobilized chelators ranging from DTPA to S-containing soft bases have been synthetized and investigated for ability to suppress intestinal uptake of /sup 109/Cd/sup 2+/ in mice. Dextran-O-ethyl-mercaptan, xanthates derived from polysaccharides and polyvinyl alcohol, dithiocarbamates of polyethylene imine and aminoethyl cellulose, and DTPA immobilized on aminopropyl silica were all ineffective. DTPA immobilized on aminoethyl cellulose even enhanced the intestinal uptake. The macromolecular chelators were without extensive effect on organ distribution of absorbed cadmium, except for dithiocarbamate immobilized on polyethylene imine, which enhanced the deposition of cadmium in several organs including the brain. Although the results are discouragign, they indicate that desing and synthesis of immobilized vicinal dithio compounds may represent an avenue for development of non-absorbable chelators with high affinity for cadmium.

  10. Mixed-chelate therapy of intratracheally deposited cadmium oxide

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

    Rose, Frisco; Hodak, Miroslav; Bernholc, Jerry

    2011-03-01

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

  12. Chelated Ruthenium Catalysts for Z-Selective Olefin Metathesis

    OpenAIRE

    Endo, Koji; Grubbs, Robert H.

    2011-01-01

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

  13. Μethods of iron chelation therapy: a bibliographic review

    OpenAIRE

    Maria Agapiou; Elpida Georgiadi

    2012-01-01

    "Iron Chelation Therapy" is a term used to describe the procedure of removing excess iron from the body, which is applied after a total of approximately 20 blood transfusions or when serum ferritin levels rise above 1000 ng/ml. Aim: The purpose of the present paper is a retrospective search in bibliography, concerning the methods of iron chelation treatment for patients with hemochromatosis owing to their undergoing multiple blood transfusions. Method: The methology followed, included the sea...

  14. EDTA chelation therapy for cardiovascular disease: a systematic review

    OpenAIRE

    Wu Ping; Seely Dugald MR; Mills Edward J

    2005-01-01

    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 ...

  15. Chelation: Harnessing and Enhancing Heavy Metal Detoxification—A Review

    OpenAIRE

    Sears, Margaret E.

    2013-01-01

    Toxic metals such as arsenic, cadmium, lead, and mercury are ubiquitous, have no beneficial role in human homeostasis, and contribute to noncommunicable chronic diseases. While novel drug targets for chronic disease are eagerly sought, potentially helpful agents that aid in detoxification of toxic elements, chelators, have largely been restricted to overt acute poisoning. Chelation, that is multiple coordination bonds between organic molecules and metals, is very common in the body and at the...

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

    OpenAIRE

    Franz, Katherine J.

    2013-01-01

    The traditional notion of chelation therapy is the administration of a chemical agent to remove metals from the body. But formation of a metal-chelate can have biological ramifications that are much broader than metal elimination. Exploring these other possibilities could lead to pharmacological interventions that alter the concentration, distribution, or reactivity of metals in targeted ways for therapeutic benefit. This review highlights recent examples that showcase four general strategies...

  17. Antioxidant, Free Radical Scavenging and Metal Chelating Characteristics of Propolis

    OpenAIRE

    Hikmet Geckil; Burhan Ates; Gokhan Durmaz; Selim Erdogan; Ismet Yilmaz

    2005-01-01

    This study was undertaken to determine the reducing characteristics, metal chelating capability, anti-lipid peroxidative and antiradical properties of propolis compared to two widely used artificial antioxidants, Butylated Hydroxyanisole (BHA) and Butylated Hydroxytoluene (BHT). The water and ethanol extracts of propolis showed significantly a different degree of metal chelating, radical scavenging activity and reducing power. In general, ethanol extracts of propolis showed higher activity re...

  18. Hydrogen peroxide- metals- chelating agents; interactions and analytical techniques

    OpenAIRE

    Rämö, J.

    2003-01-01

    Abstract Information about interactions among metals, hydrogen peroxide and chelating agents is needed to develop environmental technology and the operating efficiency of modern elemental chlorine free and total chlorine free bleaching processes. The work presented here focused on the properties of metal chelates and corrosion of titanium in an alkaline hydrogen peroxide solution. A comparative study between three rapid analysis methods, ICP-AES, XRF and ISE, was performed in pulp matrix a...

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

    International Nuclear Information System (INIS)

    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

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

    International Nuclear Information System (INIS)

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

  1. THE STUDIES ON CHELATING FIBER V.ADSORPTION BEHAVIOR OF Au3+ ONTO CHELATING FIBER CONTAINING AMIDOXIME GROUPS

    Institute of Scientific and Technical Information of China (English)

    LINWeiping; LUYun; 等

    1992-01-01

    The adsorption behavior of ionic gold onto chelating fiber containing amidoxime groups was investigated. The chelating fiber presents high adsorption capacity for ionic gold Au3+(up to 626mg/g,when the content of amidoxime group reaches 7.59mmol/g),and possesses the ability to reduce the Au3+ into metallic gold,In the redox process,the amidoxime group is oxidized into carboxyl group.

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

    OpenAIRE

    Andersen, Ole; Aaseth, Jan

    2002-01-01

    Successful in vivo chelation treatment of metal intoxication requires that a significant fraction of the administered chelator in fact chelate the toxic metal. This depends on metal, chelator, and organism-related factors (e.g., ionic diameter, ring size and deformability, hardness/softness of electron donors and acceptors, route of administration, bioavailability, metabolism, organ and intra/extracellular compartmentalization, and excretion). In vivo chelation is not necessarily an equilibri...

  3. Photorefractive keratectomy for moderate myopia with the VISX and Summit excimer lasers: a retrospective study Ceratectomia fotorrefrativa para correção de miopia moderada com excimer lasers VISX e Summit: estudo retrospectivo

    OpenAIRE

    João C. Ribeiro; Jean M. Ancel; McDonald, Marguerite B; Ray J. Varnell

    2000-01-01

    Purpose: To present photorefractive keratectomy (PRK) results for myopia ranging from -4,00 to - 6,00 diopters performed with the VISX and Summit excimer lasers. Methods: To be eligible for this study, patients had to be 20 to 45 years of age, have -4.00 to -6.00 diopters of myopia and have no more than 1 D of astigmatism. The Summit group was composed of 51 eyes. The baseline preoperative spherical equivalent of myopia was -5.22 ± 0.17 and surgeries were performed with the Excimed UV ...

  4. Phototherapeutic, photobiologic, and photosensitizing properties of khellin

    Energy Technology Data Exchange (ETDEWEB)

    Morliere, P.; Hoenigsmann, H.A.; Averbeck, D.; Dardalhon, M.; Hueppe, G.O.; Ortel, B.; Santus, R.; Dubertret, L.

    1988-05-01

    Khellin, whose chemical structure closely resembles that of psoralen, is reported to be an efficient drug for treating vitiligo when combined with ultraviolet A irradiation. Photobiological activity on yeast is found to be much lower than that of bifunctional psoralens such as 5-methoxypsoralen. In vitro experiments reveal that khellin is a poor photosensitizer. It behaves as a monofunctional agent with respect to DNA photoaddition. It does not photoinduce cross-links in DNA in vitro or in Chinese hamster cells in vivo. This behavior may explain the low photogenotoxicity in yeast and the lack of phototoxic erythemal response when treating vitiligo with khellin.

  5. The Changes of TGF-α, TGF-β1 and Basic FGF Messenger RNA Expression in Rabbit Cornea after Photorefractive Keratectomy

    Institute of Scientific and Technical Information of China (English)

    Yisheng Zhong; Yingrning Zhou; Jingcai Lian; Wen Ye; Kangsun Wang; Feng Cheng

    2000-01-01

    Objective: To study the mechanism of haze formation and investigate the expression changes of transforming growth factor-αα(TGF-αα), transforming growth factor-β1 (TGF-β1)and basic fibroblast growth factor (bFGF) mRNA in corneal epithelium and stroma after photorefractive keratectomy (PRK).Methods: Sixteen white rabbits were randomly divided into 4 groups, and PRK was performed on each eye of 12 rabbits. The haze formation was examined under a slit-lamp microscope at the 1st, 2na and 3ra month after PRK, and the expressions of TGF-αα , TGF-βi and bFGF mRNA were detected with in situ hybridization.Results: The corneal haze formed at the 1st month after PRK. The most prominent haze formation was observed at the 2nd month, and declined gradually at the 3ra month after ablation. TGF-αα mRNA expression was presented on the normal corneal epithelium and not on the corneal stroma. TGF-βl and bGFG mRNA were expressed by both corneal epitheliurn and stroma. The capacities for cornea tissue expression of three growth factors mRNA increased after PRK, and the peaks appeared on the 1s, 2na month. The extent for expressions of three growth factors related proportionally to the haze formation.Conclusion: Three growth factors took part in promoting corneal wound healing after PRK, and might contribute to corneal haze formation and development.

  6. Evaluation of the prophylactic use of mitomycin-C to inhibit haze formation after photorefractive keratectomy in high myopia: a prospective clinical study

    Directory of Open Access Journals (Sweden)

    Fotouhi Akbar

    2004-09-01

    Full Text Available Abstract Background To study the effect of prophylactic application of mitomycin-C on haze formation in photorefractive keratectomy (PRK for high myopia. Methods Fifty-four eyes of 28 myopic patients were enrolled in this prospective study. All eyes were operated by PRK followed by 0.02% mitomycin-C application for two minutes and washed with 20 ml normal saline afterwards. All eyes were examined thoroughly on the first 7 days and one month after surgery; 48 eyes (88.9% at 3 and 6 months postoperatively. Hanna grading (in the scale of 0 to 4+ was used for assessment of corneal haze. Results The mean spherical equivalent refraction (SE was -7.08 diopters (D ± 1.11 (SD preoperatively. Six months after surgery, 37 eyes (77.1% achieved an uncorrected visual acuity (UCVA of 20/20 or better, all eyes had a UCVA of 20/40 or better and 45 (93.7% eyes had an SE within ± 1.00D. One month postoperatively, 2 eyes (3.7% had grade 0.5+ of haze, while at 3 and 6 months after surgery no visited eye had haze at all. All eyes had a best corrected visual acuity (BCVA of 20/40 or better and there were no lost lines in BCVA by 6 months after surgery. In spatial frequencies of 6 and 12 cycles per degree contrast sensitivity had decreased immediately after PRK and it had increased 1.5 lines by the 6th postoperative month compared to the preoperative data. Conclusions The results show the efficacy of mitomycin-C in preventing corneal haze after treatment of high myopia with PRK. This method- PRK + mitomycin-C – can be considered an alternative treatment for myopic patients whose corneal thicknesses are inadequate for laser in situ keratomileusis (LASIK. However, the results should be confirmed in longer follow-ups.

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

    International Nuclear Information System (INIS)

    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 370C, 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

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

    International Nuclear Information System (INIS)

    Albumin microspheres have been synthesized eith 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 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 hr. Since labeling is by chelation, the microspheres may also be tagged with other metallic radionuclides

  9. Antioxidant, Free Radical Scavenging and Metal Chelating Characteristics of Propolis

    Directory of Open Access Journals (Sweden)

    Hikmet Geckil

    2005-01-01

    Full Text Available This study was undertaken to determine the reducing characteristics, metal chelating capability, anti-lipid peroxidative and antiradical properties of propolis compared to two widely used artificial antioxidants, Butylated Hydroxyanisole (BHA and Butylated Hydroxytoluene (BHT. The water and ethanol extracts of propolis showed significantly a different degree of metal chelating, radical scavenging activity and reducing power. In general, ethanol extracts of propolis showed higher activity regarding these parameters. Synthetic antioxidants showed better activities than both propolis extracts for antioxidant properties, utilizing a -carotene bleaching method. At higher concentrations, the reducing power of ethanol extract of propolis was similar to that of artificial antioxidants. The metal chelating activity of both water and ethanol extracts of propolis was comparable to that of EDTA and significantly higher than both BHA and BHT.

  10. Encapsulation and retention of chelated-copper inside hydrophobic nanoparticles

    DEFF Research Database (Denmark)

    Hervella, Pablo; Parra, Elisa; Needham, David

    2016-01-01

    Trioleate (Triolein) with copper using the hydrophobic chelator Octaethyl porphyrin (OEP). RESEARCH PLAN AND METHODS: The research plan for this study was to (1) Formulate nanoparticles and control nanoparticle size using a modification of the solvent injection technique, named fast ethanol injection; (2......) 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...... 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...

  11. Timing of early chelating therapy for acute uranium intoxication

    International Nuclear Information System (INIS)

    Rats were treated with DTPA and H-73-10 intraperitoneal injections 15 minutes to 4 days after acute uranium intoxication. The mortality and changes in body weight, kidney weight, renal histology and histochemistry were investigated. The results show that the renal damage could be diminished significantly by chelating therapy started 15 minutes and 6 hours after urnium poisoning. Single large dose injection (1 g/kg weight) of H-73-10 yielded the best result, and daily 0.5 g/kg of H-73-10 injection for 5 days is the next, both are better than single injection of DTPA (1 g/kg body weight). One day after intoxication there was still some protective effect. On the contrary, if the chelating therapy started 2-4 days after urnium poisoning it would increase the renal damage and the mortality. This is of great value to the correct selection of timing of chelating therapy for uranium intoxication

  12. Extraction rate of metal ion by chelating agent

    International Nuclear Information System (INIS)

    In order to clarify the extraction mechanism of metal ion by a chelating agent, it is problematic to infer the mechanism on the basis of the dependence of the extraction rate upon the concentration of the agent. For this purpose, the information as follows is essential: (1) computation of physical chemistry constants of the chelating agent, (2) the reaction rate for chelate formation with the metal ion in the water phase and the mechanism, and (3) the measurement of the extraction rate by use of the apparatus for which the oil/water interface area and the interface-material transfer coefficient are known. It is then necessary to establish the design guidance of reaction field and separation field via the accumulation of the experimental results. (Mori, K.)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2007-07-01

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

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

    International Nuclear Information System (INIS)

    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)

  15. Clinical monitoring and management of complications related to chelation therapy in patients with β-thalassemia.

    Science.gov (United States)

    Saliba, Antoine N; El Rassi, Fuad; Taher, Ali T

    2016-01-01

    Iron chelating agents - deferoxamine (DFO), deferiprone (DFP), and deferasirox (DFX) - are used to treat chronic iron overload in patients with β-thalassemia in an attempt to reduce morbidity and mortality related to siderosis. Each of the approved iron chelating agents has its own advantages over the others and also has its own risks, whether related to over-chelation or not. In this review, we briefly discuss the methods to monitor the efficacy of iron chelation therapy (ICT) and the evidence behind the use of each iron chelating agent. We also portray the risks and complications associated with each iron chelating agent and recommend strategies to manage adverse events. PMID:26613264

  16. Combinational chelation therapy abrogates lead-induced neurodegeneration in rats

    International Nuclear Information System (INIS)

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

  17. 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.

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

    International Nuclear Information System (INIS)

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

  19. SEPARATION OF PLUTONIUM FROM LANTHANUM BY CHELATION-EXTRACTION

    Science.gov (United States)

    James, R.A.; Thompson, S.G.

    1958-12-01

    Plutonium can be separated from a mixture of plutonlum and lanthanum in which the lanthanum to plutonium molal ratio ls at least five by adding the ammonium salt of N-nitrosoarylhydroxylamine to an aqueous solution having a pH between about 3 and 0.2 and containing the plutonium in a valence state of at least +3, to form a plutonium chelate compound of N-nitrosoarylhydroxylamine. The plutonium chelate compound may be recovered from the solution by extracting with an immiscible organic solvent such as chloroform.

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

    International Nuclear Information System (INIS)

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

  1. 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 or...

  2. Physiological response of Moringa oleifera to stigmasterol and chelated zinc

    OpenAIRE

    KARIMA GAMAL EL-DIN; IMAN MAHMOUD TALAAT; MOHAMED ABDEL-GHANY BEKHETA; ABDALLA EL-MOURSI

    2012-01-01

    El-Moursi A, Talaat IM, Bekheta MA, Gamal El-Din K. 2012. Physiological response of Moringa oleifera to stigmasterol and chelated zinc. Nusantara Bioscience 4: 118-123. Two pot experiments were carried out in the screen of the National Research Centre, Dokki, Giza, Egypt, during two successive seasons (2009/2010 and 2010/2011), respectively to study the effect of foliar spray with chelated zinc (100, 200 and 300 mg/L) and stigmasterol (50, 100 and 150 mg/L) on growth and chemical constituents...

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

    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)

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

    Science.gov (United States)

    ... NIH Trial of EDTA Chelation Therapy for Coronary Heart Disease Preliminary results from the Trial to Assess Chelation ... and complete it. Study Background What is coronary heart disease? Coronary heart disease (CHD) is the most common ...

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

    Science.gov (United States)

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

    2016-04-01

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

  7. MDs remain sceptical as chelation therapy goes mainstream in Saskatchewan

    OpenAIRE

    Oliver, M.

    1997-01-01

    The College of Physicians and Surgeons of Saskatchewan recently agreed to allow physicians to administer chelation therapy. Supporters, relying on anecdotal evidence, say it works wonders in overcoming heart disease, but many physicians remain profoundly sceptical. In Saskatchewan, the college decision has proved popular with patients but has drawn an angry reaction from doctors.

  8. Role of Chelation During Pregnancy in the Lead Poisoned Patient

    OpenAIRE

    Brown, Mary Jean

    2013-01-01

    Cultural and environmental factors can cause lead poisoning in the pregnant patient. The data regarding the reproductive risks associated with chelation during human pregnancy are sparse. Assessment of the exposure setting, including anticipatory counseling for each pregnant woman, would help assure the ideal outcome of no added lead intake.

  9. Laccase Immobilization by Chelated Metal Ion Coordination Chemistry

    Directory of Open Access Journals (Sweden)

    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.

  10. Chelation And Extraction Of Metals For GC-MS Analysis

    Science.gov (United States)

    Sinha, Mahadeva P.

    1995-01-01

    Chelation followed by supercritical-fluid extraction enables mass-spectrometric analysis. When fully developed, method implemented in field-portable apparatus for detection and quantification of metals in various matrices without need for elaborate preparation of samples. Used to analyze soil samples for toxic metals.

  11. Sequestration of zinc oxide by fimbrial designer chelators

    DEFF Research Database (Denmark)

    Kjærgaard, Kristian; Sørensen, Jack K; Schembri, Mark; Klemm, Per

    2000-01-01

    Type 1 fimbriae are surface organelles of Escherichia coli. By engineering a structural component of the fimbriae, FimH, to display a random peptide library, we were able to isolate metal-chelating bacteria. A library consisting of 4 x 10(7) independent clones was screened for binding to Zn...

  12. Reversal of haemochromatotic cardiomyopathy in beta thalassaemia by chelation therapy.

    OpenAIRE

    Politi, A; M. Sticca; Galli, M

    1995-01-01

    Haemochromatotic cardiomyopathy is the main cause of morbidity and mortality in patients with beta thalassaemia major. Once congestive heart failure develops most patients die in a few months. Congestive heart failure was reversed and echocardiographic findings were restored to normal in a 24 year old woman with beta thalassaemia who resumed treatment with chelation therapy (desferrioxamine).

  13. f-Element Ion Chelation in Highly Basic Media

    International Nuclear Information System (INIS)

    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

  14. Commentary on the Abuse of Metal Chelation Therapy in Patients with Autism Spectrum Disorders

    OpenAIRE

    Brent, Jeffrey

    2013-01-01

    Approximately half a million patients with autism spectrum disorders are subjected to chelation therapy in the US annually. The overwhelming majority of such cases are chelated for non-accepted medical indications. These patients may seek evaluation when a urine sample is assayed after the administration of a chelating agent and the values obtained have been improperly compared to references ranges for non-chelated urines, causing falsely elevated results. Legitimate practitioners confronted ...

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

    International Nuclear Information System (INIS)

    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

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

    Energy Technology Data Exchange (ETDEWEB)

    Kos, Bostjan; Lestan, Domen

    2004-11-01

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

  17. Investigation of the chelation effect on the voltammetric behaviour of selected metals

    International Nuclear Information System (INIS)

    Iron, cadmium, aluminum and chromium could be easily determined by voltammetric methods. The chelation behaviour of chelating agents like hydroxyquinoline, NaDEDC, cupferron etc. have been investigated on the voltammetric behavior of these metals. The results were compared with the spectro fluorimetric investigation of these metal chelates and a relation between voltammetric and fluorimetric behaviour have been established. (author)

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

    Science.gov (United States)

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

  19. Visual rehabilitation in low-moderate keratoconus:intracorneal ring segment implantation followed by same-day topography-guided photorefractive keratectomy and collagen cross linking

    Institute of Scientific and Technical Information of China (English)

    Ferial; M.Zeraid; Asma; A; Jawkhab; Waleed; S; Al-Tuwairqi; Uchechukwu; L.Osuagwu

    2014-01-01

    AIM:To present the results of same-day topographyguided photorefractive keratectomy(TG-PRK) and corneal collagen crosslinking(CXL) after previous intrastromal corneal ring segment(ISCR) implantation for keratoconus.METHODS:An experimental clinical study on twentyone eyes of 19 patients aged 27.1±6.6y(range 19-43y),with low to moderate keratoconus who were selected to undergo customized TG-PRK immediately followed by same-day CXL, 9mo after ISCR implantation in a university ophthalmology clinic. Refraction, uncorrected distance visual acuities(UDVA) and corrected distance visual acuities(CDVA), keratometry(K) values, central corneal thickness(CCT) and coma were assessed 3mo after TG-PRK and CXL.RESULTS:After TG-PRK/CXL: the mean UDVA(logMAR) improved significantly from 0.66 ±0.41 to 0.20 ±0.25(P <0.05); Kflatvalue decreased from: 48.44±3.66 D to43.71±1.95 D; Ksteepvalue decreased from 45.61±2.40 D to41.56±2.05 D; Kaveragealso decreased from 47.00±2.66 D to42.42 ±2.07 D(P <0.05 for all). The mean sphere andcylinder decreased significantly post- surgery from,- 3. 10 ± 2. 99 D to-0.11±0.93 D and from-3.68±1.53 to-1.11 ±0.75 D respectively, while the CDVA, CCT and coma showed no significant changes. Compared to postISCR, significant reductions(P <0.05 or all) in all K values,sphere and cylinder were observed after TG-PRK/CXL.CONCLUSION:Same-day combined topography-guided PRK and corneal crosslinking following placement of ISCR is a safe and potentially effective option in treating low-moderate keratoconus. It significantly improves all visual acuity, reduced keratometry, sphere and astigmatism, but causes no change in central corneal thickness and coma.

  20. A retrospective analysis of the postoperative use of loteprednol etabonate gel 0.5% following laser-assisted in situ keratomileusis or photorefractive keratectomy surgery

    Directory of Open Access Journals (Sweden)

    Salinger CL

    2015-11-01

    Full Text Available Clifford L Salinger,1 Michael Gordon,2 Mitchell A Jackson,3 Theodore Perl,4 Eric Donnenfeld5 1VIP Laser Eye Center, Palm Beach Gardens, FL, 2Gordon Weiss Schanzlin Vision Institute, San Diego, CA, 3Jacksoneye, Lake Villa, IL, 4Corneal Associates of New Jersey, Fairfield, NJ, 5Ophthalmic Consultants of Long Island, Garden City, NY, USA Background: While loteprednol etabonate ophthalmic gel 0.5% (LE gel is approved for treatment of postoperative ocular inflammation and pain, there have been no reported studies in patients undergoing laser-assisted in situ keratomileusis (LASIK or photorefractive keratectomy (PRK.Methods: This was a retrospective chart review conducted at five refractive surgical centers in the USA. Data were collected from primary LASIK or PRK surgery cases in which LE gel was used postoperatively as the clinician’s routine standard of care and in which patients were followed-up for up to 6 months. Data extracted from charts included patient demographics, surgical details, LE gel dosing regimen, pre- and postsurgical refractive characteristics, intraocular pressure (IOP measurements, and visual acuity. Primary outcomes included postoperative IOP elevations, adverse events, and early discontinuations.Results: Data were collected on 189 LASIK eyes (96 patients and 209 PRK eyes (108 patients. Mean (standard deviation [SD] years of age at surgery was 36.0 (11.7 and 33.9 (11.3 in LASIK and PRK patients. LE gel was prescribed most often four times daily during the first postoperative week, regardless of procedure; the most common treatment duration was 7–14 days in LASIK and ≥30 days in PRK patients. No unusual corneal findings or healing abnormalities were reported. Mean postoperative uncorrected distance visual acuity was 20/24 in LASIK and 20/30 in PRK eyes. Mild/trace corneal haze was reported in 20% of PRK patients; two PRK patients with moderate/severe corneal haze were switched to another corticosteroid. Mean postoperative

  1. Safety, Efficacy, Predictability and Stability Indices of Photorefractive Keratectomy for Correction of Myopic Astigmatism with Plano-Scan and Tissue-Saving Algorithms

    Directory of Open Access Journals (Sweden)

    Mehrdad Mohammadpour

    2013-10-01

    Full Text Available Purpose: To assess the safety, efficacy and predictability of photorefractive keratectomy (PRK [Tissue-saving (TS versus Plano-scan (PS ablation algorithms] of Technolas 217z excimer laser for correction of myopic astigmatismMethods: In this retrospective study one hundred and seventy eyes of 85 patients (107 eyes (62.9% with PS and 63 eyes (37.1% with TS algorithm were included. TS algorithm was applied for those with central corneal thickness less than 500 µm or estimated residual stromal thickness less than 420 µm. Mitomycin C (MMC was applied for 120 eyes (70.6%; in case of an ablation depth more than 60 μm and/or astigmatic correction more than one diopter (D. Mean sphere, cylinder, spherical equivalent (SE refraction, uncorrected visual acuity (UCVA, best corrected visual acuity (BCVA were measured preoperatively, and 4 weeks,12 weeks and 24 weeks postoperatively.Results: One, three and six months postoperatively, 60%, 92.9%, 97.5% of eyes had UCVA of 20/20 or better, respectively. Mean preoperative and 1, 3, 6 months postoperative SE were -3.48±1.28 D (-1.00 to -8.75, -0.08±0.62D, -0.02±0.57 and -0.004± 0.29, respectively. And also, 87.6%, 94.1% and 100% were within ±1.0 D of emmetropia and 68.2, 75.3, 95% were within ±0.5 of emmetropia. The safety and efficacy indices were 0.99 and 0.99 at 12 weeks and 1.009 and 0.99 at 24 weeks, respectively. There was no clinically or statistically significant difference between the outcomes of PS or TS algorithms or between those with or without MMC in either group in terms of safety, efficacy, predictability or stability. Dividing the eyes with subjective SE≤4 D and SE≥4 D postoperatively, there was no significant difference between the predictability of the two groups. There was no intra- or postoperative complication.Conclusion: Outcomes of PRK for correction of myopic astigmatism showed great promise with both PS and TS algorithms.

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

    OpenAIRE

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

    2015-01-01

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

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

    Science.gov (United States)

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

    2016-02-01

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

  4. Synthesis of New Bis(3-hydroxy-4-pyridinone) Ligands as Chelating Agents for Uranyl Complexation

    OpenAIRE

    Bo Jin; Rongzong Zheng; Rufang Peng; Shijin Chu

    2016-01-01

    Five new bis(3-hydroxy-4-pyridinone) tetradentate chelators were synthesized in this study. The structures of these tetradentate chelators were characterized by 1H-NMR, 13C-NMR, FT-IR, UV-vis, and mass spectral analyses. The binding abilities of these tetradentate chelators for uranyl ion at pH 7.4 were also determined by UV spectrophotometry in aqueous media. Results showed that the efficiencies of these chelating agents are dependent on the linker length. Ligand 4b is the best chelator and ...

  5. Synthesis of New Bis(3-hydroxy-4-pyridinone) Ligands as Chelating Agents for Uranyl Complexation.

    Science.gov (United States)

    Jin, Bo; Zheng, Rongzong; Peng, Rufang; Chu, Shijin

    2016-01-01

    Five new bis(3-hydroxy-4-pyridinone) tetradentate chelators were synthesized in this study. The structures of these tetradentate chelators were characterized by ¹H-NMR, (13)C-NMR, FT-IR, UV-vis, and mass spectral analyses. The binding abilities of these tetradentate chelators for uranyl ion at pH 7.4 were also determined by UV spectrophotometry in aqueous media. Results showed that the efficiencies of these chelating agents are dependent on the linker length. Ligand 4b is the best chelator and suitable for further studies. PMID:27005598

  6. Long-term results of photorefractive keratectomy for myopia and myopic astigmatism Resultados a longo prazo de ceratectomia fotorefrativa para miopia e astigmatismo miópico

    Directory of Open Access Journals (Sweden)

    Ester Sakae Yamazaki

    2007-12-01

    Full Text Available PURPOSE: To assess the long-term refractive outcomes of photorefractive keratectomy in myopia and myopic astigmatism. METHODS: A retrospective study of 120 photorefractive keratectomy operated eyes with at least four-year follow-up (maximum of 96 months, mean follow-up 55 months. We divided patients into group 1 (G1 spherical equivalent (SE up to -4.00 diopters (D and group 2 (G2 SE >-4.00 D. The Summit Apex Plus® excimer laser was used for ablation. All eyes were analyzed in terms of uncorrected and best spectacle corrected visual acuity (UCVA/BSCVA and cycloplegic refraction. Data were analyzed using the Refractive Surgery Consultant Elite database software. RESULTS: G1 with 85 eyes (49 patients presented mean SE -2.42 D and G2 with 35 eyes (22 patients and mean SE of -4.45 D. Ninety-four percent of eyes in G1 and 82.9% of G2 were within ±1.00 D of emmetropia at 4 years. The UCVA was 20/30 or better in 82.0% of G1 eyes and 77.0% of G2 in the last postoperative follow-up. No patient lost more than one line in G2 compared to 13.0% in G1. Eyes that gained one or more lines after 4-year follow-up were 11.9% G1 and 2.9% in G2, respectively. A statistically significant positive correlation was found between achieved versus attempted refractive correction in both groups (r=0.925, pOBJETIVO: Relatar os resultados a longo prazo da cirurgia de ceratectomia fotorefrativa em miopia e astigmatismo miópico. MÉTODOS: Estudo retrospectivo de120 olhos operados de ceratectomia fotorefrativa com um mínimo intervalo de 4 anos de seguimento pós-operatório (máximo de 96 meses e seguimento médio de 55 meses. Dividimos em grupo 1 (G1 com equivalente esférico (SE até -4.00 dioptrias (D e grupo 2(G2 SE > -4.00 D. O excimer laser Summit Apex Plus® foi usado na ablação. Foram obtidas acuidade visual não corrigida (UCVA e melhor acuidade visual corrigida (BSCVA e refração sob cicloplegia. Os dados foram analisados utilizando o programa Refractive Surgery

  7. A comparison study of radiostrontium chelation with chitin, chitosan, EDTA and DTPA

    International Nuclear Information System (INIS)

    Chitin and chitosan are nontoxic natural chelators that chelate radiostrontium effectively. The purpose of this study was to compare radiostrontium chelation of chitin and chitosan with that of well known chemical chelators, namely EDTA and DTPA. The chelaton rates of chitin, chitosan, EDTA and DTPA were compared using a column chromatography method (Sephadex G-25M, Sweden). Three kinds of chitins and four kinds of chitosans were used. All of them were water soluble. Phosphated chitosan showed the highest chelation yield of 97% at pH 7. All of chitins, chitosans, EDTA and DTPA showed chelation yield of more than 90% independent of varing pH level. Chitin and chitosan have similar chelation rate as compared with EDTA and DTPA

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

    International Nuclear Information System (INIS)

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

  9. Doping of graphene nanomeshes by ion-chelation

    Science.gov (United States)

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

    2013-03-01

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

  10. Chelation studies involving decontamination of light lanthanides by polyaminopolycarboxylic

    International Nuclear Information System (INIS)

    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

  11. Lanthanides caged by the organic chelates; structural properties

    Science.gov (United States)

    Smentek, Lidia

    2011-04-01

    The structure, in particular symmetry, geometry and morphology of organic chelates coordinated with the lanthanide ions are analyzed in the present review. This is the first part of a complete presentation of a theoretical description of the properties of systems, which are widely used in technology, but most of all, in molecular biology and medicine. The discussion is focused on the symmetry and geometry of the cages, since these features play a dominant role in the spectroscopic activity of the lanthanides caged by organic chelates. At the same time, the spectroscopic properties require more formal presentation in the language of Racah algebra, and deserve a separate analysis. In addition to the parent systems of DOTA, DOTP, EDTMP and CDTMP presented here, their modifications by various antennas are analyzed. The conclusions that have a strong impact upon the theory of the energy transfer and the sensitized luminescence of these systems are based on the results of numerical density functional theory calculations.

  12. 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.

  13. Improved paramagnetic chelate for molecular imaging with MRI

    International Nuclear Information System (INIS)

    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

  14. 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.

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

    Gattermann, Norbert

    2012-01-01

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

  18. Toxicological studies of a new chelating agent 8102

    International Nuclear Information System (INIS)

    The results of toxicological studies of a new chelating agent 8102 in different kinds of animals (mice, rats, rabbits and dogs) were reported. The results show that for mice, LD50 is 782 +- 21 mg/kg (i.v) and 3.17 +- 0.06 g/kg (i.m), and for rats, LD50 is 478 +- 15 mg/kg (i.v) and 3.04 +- 0.08 g/kg (i.m). In subacute experiments for dogs, the agent 8102 in doses of 50, 100, 150 mg(kg.day) was injected i.m. and for control group 0.9% saline was injected i.m.. Treatment was continued for 30 days. In pathological and clinical chemical analysis no essential change was observed. The experimental results suggest that the toxicity of this new chelating agent 8102 is low

  19. Meta-analysis of the safety of iron chelating agents

    OpenAIRE

    Li, Niya; 李妮婭

    2014-01-01

    Background: Thalassaemia is a genetic disorder disease, one of the most clinically relevant haemoglobinopathies in paediatric population. It interferes with the synthesis of haemoglobin chain. For the sake of maintaining the serum haemoglobin at a normal level, regular blood cell transfusion is required to the patients with thalassaemia. In general, patients with thalassaemia are often diagnosed at an early age and need to take a life-long iron chelating therapy to prevent the multi-organ...

  20. Studies on the chelation of aluminium for biological application

    International Nuclear Information System (INIS)

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

  1. CHELATION THERAPY FOR IRON OVERLOAD: NURSING PRACTICE IMPLICATIONS

    OpenAIRE

    Eckes, Ellen J.

    2011-01-01

    Many diseases of the blood are treated with blood transfusion therapy. Chronic transfusions can cause iron overload, and, if untreated, can cause end-organ damage. Chelation therapy provides a way of treating iron overload and minimizing its adverse effects. Nurses need to understand that iron overload is a consequence of chronic blood transfusion, and they need to know what effects it has on end-organs and what treatment options are available.

  2. Chelate-Assisted Heavy Metal Movement Through the Root Zone

    Science.gov (United States)

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

    2001-12-01

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

  3. 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 : chelates * nanoparticles * polymers Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.349, year: 2012

  4. 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.

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

    Science.gov (United States)

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

    2015-10-01

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

  6. Tumor targeting of radiolabeled antibodies using HYNIC chelate

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

    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.

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

    International Nuclear Information System (INIS)

    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

  9. High precision isotopic ratio analysis of volatile metal chelates

    International Nuclear Information System (INIS)

    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 50Cr, 60Ni, and 65Cu isotopes covering the range 0.1-1010.7 at. % excess. A separate multiple isotope calibration curve was similarly prepared using enriched 60Ni (0.02-2.15 at. % excess) and 62Ni (0.23-18.5 at. % excess). The samples were analyzed by GC/CI/MS. Human plasma, containing enriched 26Mg and 44Ca, was analyzed by EI/MS. 1 figure, 5 tables

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

    International Nuclear Information System (INIS)

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

  11. 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.

  12. Brazilian Thalassemia Association protocol for iron chelation therapy in patients under regular transfusion

    OpenAIRE

    Monica Pinheiro de Almeida Verissimo; Sandra Regina Loggetto; Antonio Fabron Junior; Giorgio Roberto Baldanzi; Nelson Hamerschlak; Juliano de Lara Fernandes; Aderson da Silva Araujo; Clarisse Lopes de Castro Lobo; Kleber Yotsumoto Fertrin; Vasilios Antonios Berdoukas; Renzo Galanello

    2013-01-01

    In the absence of an iron chelating agent, patients with beta-thalassemia on regular transfusions present complications of transfusion-related iron overload. Without iron chelation therapy, heart disease is the major cause of death; however, hepatic and endocrine complications also occur. Currently there are three iron chelating agents available for continuous use in patients with thalassemia on regular transfusions (desferrioxamine, deferiprone, and deferasirox) providing good results in red...

  13. The Role of Chelation in the Treatment of Other Metal Poisonings

    OpenAIRE

    Smith, Silas W.

    2013-01-01

    These proceedings will review the role of chelation in five metals—aluminum, cadmium, chromium, cobalt, and uranium—in order to illustrate various chelation concepts. The process of “chelation” can often be oversimplified, leading to incorrect assumptions and risking patient harm. For chelation to be effective, two critical assumptions must be fulfilled: the presumed “metal toxicity” must correlate with a given body or a particular compartment burden, and reducing this compartmental or the bo...

  14. Alkenes as Chelating Groups in Diastereoselective Additions of Organometallics to Ketones

    OpenAIRE

    Raffier, Ludovic; Gutierrez, Osvaldo; Stanton, Gretchen R.; Kozlowski, Marisa C.; Walsh, Patrick J.

    2014-01-01

    Alkenes have been discovered to be chelating groups to Zn(II), enforcing highly stereoselective additions of organozincs to β,γ-unsaturated ketones. 1H NMR studies and DFT calculations provide support for this surprising chelation mode. The results expand the range of coordinating groups for chelation-controlled carbonyl additions from heteroatom Lewis bases to simple C–C double bonds, broadening the 60 year old paradigm.

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

    OpenAIRE

    Leitch, Heather A.; Vickars, Linda M.; Chase, Jocelyn M.; Badawi, Maha A.

    2010-01-01

    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 ...

  16. Korean Guideline for Iron Chelation Therapy in Transfusion-Induced Iron Overload

    OpenAIRE

    Jang, Jun Ho; Lee, Je-Hwan; Yoon, Sung-Soo; Jo, Deog-Yeon; Kim, Hyeoung-Joon; Chung, Jooseop; Lee, Jong Wook

    2013-01-01

    Many Korean patients with transfusion-induced iron overload experience serious clinical sequelae, including organ damage, and require lifelong chelation therapy. However, due to a lack of compliance and/or unavailability of an appropriate chelator, most patients have not been treated effectively. Deferasirox (DFX), a once-daily oral iron chelator for both adult and pediatric patients with transfusion-induced iron overload, is now available in Korea. The effectiveness of deferasirox in reducin...

  17. Design, synthesis and characterization of new iron and aluminium chelating agents

    OpenAIRE

    Toso, Leonardo

    2014-01-01

    Chelation therapy is widely used for metal-unbalance related diseases, namely those due to disorders on metal metabolism, such as beta-thalassemia, hemochromatosis (Fe), and neurodegenerative diseases (Cu, Fe, Zn and Al). The study of metal chelators for clinical applications, either as chelating therapeutics able to target specific metal ions in the body, or as metal-carriers for therapeutic or imaging purposes, is a topical research area which faces up to urgent medical problems. Meta...

  18. Chelation behaviour of lanthanons with o-arsonodibenzoylmethanephenlylhydrazone

    International Nuclear Information System (INIS)

    The chelate formation reaction of La(III), Pr(III), Nd(III), Gd(III), Ho(III), and Er(III) with o-arsonodibenzoylmethanephenylhydrazone has been investigated potentiometrically and conductometrically in 40 % (ν/ν) aqueous ethanol, ionic strength 0,1 M. The order of stability constants was found to be La Gd 3+: L). The complexes have been isolated in solid state and have been characterized on the basis of elemental analysis and IR data. Coordination occurs through - NH of the hydrazo and - OH of the arsonic groups. (Authors)

  19. Chelate-modified polymers for atmospheric gas chromatography

    Science.gov (United States)

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

    1980-01-01

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

  20. New Regeneration process of heavy metals loaded chelating resin

    OpenAIRE

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

    2000-01-01

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

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

    '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 CO2 with and without added cosolvents, (2) the spectroscopic determination of preferential solvation of metal chelates by cosolvents in SC CO2 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 CO2/chelate mixtures is the equilibrium solubility of the metal chelate complex in the CO2.'

  3. 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...

  4. Synthesis of amidoxime chelating fiber and its adsorption properties for Cu(II) ion

    International Nuclear Information System (INIS)

    In order to obtain the chelating fiber for adsorbing metal ions in apple juice, the effect of different conditions on adsorption properties of chelating fiber for Cu(II) ion were discussed, such as pH and the time of ad- sorption. The isotherm of adsorption has bee confirmed. The desorption and its regeneration were simply discussed, too. The results showed that the chelating fiber had good kinetic property and the adsorbed equilibrium completed almost within 20-30 min. The adsorption properties was affected by the temperature and pH. The adsorption process fits the isothermal equation of Freundlich. The chelating fiber could be used repeatedly. (authors)

  5. Retinal detachment following excimer laser

    OpenAIRE

    Charteris, D; Cooling, R; Lavin, M; McLeod, D

    1997-01-01

    AIMS—To report the clinical presentation, surgical management, and outcome of retinal detachment following excimer laser.
METHODS—Retrospective analysis of retinal detachments observed in 11 eyes of 10 myopic patients who had previously undergone photorefractive keratectomy (PRK) or phototherapeutic keratectomy (PTK) by excimer laser.
RESULTS—Symptoms of visual loss in two eyes were initially attributed to corneal haze. In 10 of 11 eyes visualisation of the retinal detachment and causative br...

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

    International Nuclear Information System (INIS)

    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 LaNiO3 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)

  7. Detoxication and removal of uranium by phenolic chelating agents

    International Nuclear Information System (INIS)

    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

  8. Capillary gas chromatography of metal chelates of diethyl dithiocarbamates

    Energy Technology Data Exchange (ETDEWEB)

    Arain, M.A.; Bhanger, M.I. [Center of Excellence in Analytical Chemistry (Pakistan); Khuhawar, M.Y. [M.A. Kazi Inst. of Chemistry, Univ. of Sindh, Jamshoro (Pakistan)

    2002-03-01

    Capillary GC of metal chelates of diethyl dithiocarbamate (DDTC) was examined on a methylsilicone DB-1 column, (25 meter, 0.2 mm. i.d) with a film thickness of 0.25 {mu}m. Elution was carried out at the initial column temperature of 180 C and programmed at 5 C min{sup -1} to 260 C. Detection was by FID or ECD. Symmetrical peaks with bse line separation were obtained with the metal chelates of copper(II), nickel(II), cobalt(III), manganese(II) and chromium(III). The ECD gave better sensitivity than the FID with a linear calibration range of 5 - 50 {mu}g mL{sup -1} and detection limits 2.0 - 6.0 {mu}g mL{sup -1}, corresponding to 111 - 333 pg of metal ion reaching the detector. The method was applied to the determination of metal ions in water and pharmaceutical preparations with a coefficient of variation (CV) within 4.0%. When compared with a standard flame AAS method the results revealed no significant difference. (orig.)

  9. Influence of chelation therapy (DTPA) on 141Ce retention in rats

    International Nuclear Information System (INIS)

    We investigated the influence of oral and parenteral administration of chelation therapy on the retention of 141Ce in young rats. Opposite to results obtained in adult rats present results show high efficacy of oral chelation therapy in reducing radiocerium retention in the whole body and organs of suckling rats. (author) 3 refs

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

    International Nuclear Information System (INIS)

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

  11. A novel BF2-chelated azadipyrromethene-fullerene dyad: synthesis, electrochemistry and photodynamics.

    Science.gov (United States)

    Amin, Anu N; El-Khouly, Mohamed E; Subbaiyan, Navaneetha K; Zandler, Melvin E; Fukuzumi, Shunichi; D'Souza, Francis

    2012-01-01

    The synthesis, structure, electrochemistry and photodynamics of a BF(2)-chelated azadipyrromethene-fullerene dyad are reported in comparison with BF(2)-chelated azadipyrromethene without fullerene. The attachment of fullerene resulted in efficient generation of the triplet excited state of the azadipyrromethene via photoinduced electron transfer. PMID:22083226

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

    Science.gov (United States)

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

  13. Inhibitor Ranking Through QM based Chelation Calculations for Virtual Screening of HIV-1 RNase H inhibition

    DEFF Research Database (Denmark)

    Poongavanam, Vasanthanathan; Svendsen, Casper Steinmann; Kongsted, Jacob

    2014-01-01

    of the methods based on the use of a training set of molecules, QM based chelation calculations were used as filter in virtual screening of compounds in the ZINC database. By this, we find, compared to regular docking, QM based chelation calculations to significantly reduce the large number of false...

  14. Production and chelation properties of Lu-177, the isotope suitable for nuclear medicine applications

    International Nuclear Information System (INIS)

    Lutetium-177 is one of the most favoured radionuclides for radiotherapeutic applications due to its suitable nuclear characteristics. It has been mainly used in three areas: labelling of biomolecules (i.e., somatostatine analogues and monoclonal antibodies), palliative therapy of bone skeletal metastases, and radiation synovectomy. At present, Lu- labelled chelates with aminocarboxylates, like a DOTA or DTPA have been deeply investigated from the point of view of chelation properties. This research has been targeted on finding the optimal conditions of chelation to obtain high yields of chelates and on monitoring their kinetic stability, depending on particular factors (i.e., pH, molar ratios metal: ligand or duration of the reaction). The Lu-DTPA and Lu-DOTA chelates were prepared and detected radiochromatographically by TLC. For this purpose ITLC SG plates were used as a solid phase, and a mixture of hydroxylamine:methanol:water (0.2:2:4) was used as a liquid phase. (author)

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

    Directory of Open Access Journals (Sweden)

    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.

  16. Brazilian Thalassemia Association protocol for iron chelation therapy in patients under regular transfusion

    Directory of Open Access Journals (Sweden)

    Monica Pinheiro de Almeida Verissimo

    2013-01-01

    Full Text Available In the absence of an iron chelating agent, patients with beta-thalassemia on regular transfusions present complications of transfusion-related iron overload. Without iron chelation therapy, heart disease is the major cause of death; however, hepatic and endocrine complications also occur. Currently there are three iron chelating agents available for continuous use in patients with thalassemia on regular transfusions (desferrioxamine, deferiprone, and deferasirox providing good results in reducing cardiac, hepatic and endocrine toxicity. These practice guidelines, prepared by the Scientific Committee of Associação Brasileira de Thalassemia (ABRASTA, presents a review of the literature regarding iron overload assessment (by imaging and laboratory exams and the role of T2* magnetic resonance imaging (MRI to control iron overload and iron chelation therapy, with evidence-based recommendations for each clinical situation. Based on this review, the authors propose an iron chelation protocol for patients with thalassemia under regular transfusions.

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

    International Nuclear Information System (INIS)

    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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2001-01-01

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

  19. 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.

  20. Incorporation of 241Am: effectiveness of late DTPA chelation therapy

    International Nuclear Information System (INIS)

    In four persons who had incorporated 241Am probably by inhalation, a DTPA chelation therapy was initiated several months after incorporation. Excretion measurements and in vivo measurements were performed in order to quantify the enhancement of 241Am excretion and the activity distribution in the body. DTPA was administered 4-11 times as an infusion of 1 g DTPA. Daily excretion rates were raised essentially, up to factors of 65-140 (urine) and 30-50 (faeces) after the first administration. Dose calculations performed on the basis of a modified ICRP 30, Part 4 model yielded dose reductions (e.g. for subject A) of 90%, 28%, 28% and 26% for liver, bone surfaces, red bone marrow and lungs, respectively, corresponding to a reduction of the effective dose equivalent of approximately 40%. (author)

  1. Economically dissolving barium sulfate scale with a chelating agent

    Energy Technology Data Exchange (ETDEWEB)

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

    1977-06-21

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

  2. Sands of Sahara after LASIK in Avellino Corneal Dystrophy

    OpenAIRE

    Flavio Mantelli; Alessandro Lambiase; Antonio Di Zazzo; Stefano Bonini

    2012-01-01

    We report the case of a patient diagnosed with Avellino corneal dystrophy (ACD) who developed diffuse interstitial keratitis following excimer laser insitu keratomileusis (LASIK). ACD is an autosomal dominant corneal dystrophy characterized by multiple asymmetric stromal opacities that impair vision. Accepted treatments for this condition include corneal transplantation and phototherapeutic keratectomy (PTK). Our patient underwent LASIK at another institution to correct myopia. LASIK and phot...

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

    International Nuclear Information System (INIS)

    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)

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

    Science.gov (United States)

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

    2016-01-01

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

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

    Science.gov (United States)

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

    2016-01-01

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

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

    Science.gov (United States)

    Çimen, Duygu; Göktürk, Ilgım; Yılmaz, Fatma

    2016-06-01

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

  7. Ceratectomia superficial em carcinoma de células escamosas ocular em bovino Simental: Relato de caso Superficial keratectomy in ocular squamous cells carcinoma in Simmental cattle: A case report

    Directory of Open Access Journals (Sweden)

    P.D. Galera

    2001-10-01

    Full Text Available Foi encaminhado ao Hospital Veterinário da Faculdade de Medicina Veterinária da Universidade de Cuiabá um bovino com seis anos de idade, fêmea, da raça Simental, apresentando neoformação de aspecto granular no canto nasal superior da córnea e da conjuntiva. Realizaram-se ceratectomia superficial e incisão conjuntival para exérese da massa tumoral, seguido de "flap" de terceira pálpebra e terapêutica clínica apropriada. Decorridos 12 dias de pós-operatório observou-se teste de fluoresceína negativo. Pela histopatologia do tecido extraído firmou-se o diagnóstico de carcinoma de células escamosas. Até 18 meses de pós-operatório não se observou recidiva.A six-year old Simmental cow was referred to the Veterinary Hospital in Cuiaba, Brazil, with an ocular tumor involving the cornea and conjunctiva. The animal was submitted to regional anesthesia after which superficial keratectomy and conjunctival incision were performed. Third palpebral flap and adequate post-surgical therapy were employed. By the 12th post operative day the fluorescein dye test was negative. The tumor was examined by histopathology and was diagnosed as ocular squamous cells carcinoma. Relapse was not observed up to 18 months after the surgery.

  8. MR imaging of lung ventilation with aerosolized Gadolinium-chelates; MR-Bildgebung der Lungenventilation mittels aerosolierter Gadolinium-Chelate

    Energy Technology Data Exchange (ETDEWEB)

    Haage, P.; Karaagac, S.; Spuentrup, E.; Guenther, R.W. [RWTH Aachen (Germany). Klinik fuer Radiologische Diagnostik; Adam, G. [Universitaetsklinikum Hamburg-Eppendorf (Germany). Abt. fuer Diagnostische und Interventionelle Radiologie

    2003-02-01

    Purpose: To evaluate the feasibility of magnetic resonance assessment of human lung ventilation with aerosolized Gd-chelates in healthy volunteers. Materials and Methods: Five healthy adults (mean age 37 years) were studied with a 1.5 T unit. The volunteers were instructed to inhale the aerosol through an airtight facial mask for 10 minutes. The aerosol was generated with a jet-type small particle nebulizer with attached heater. Ventilation imaging was performed using a respiration-gated dynamic T{sub 1}-weighted turbo spin echo sequence (T{sub R}=199 ms, T{sub E}=8.5 ms, 12 signal averages, slice thickness 10 mm). Pulmonary signal intensity changes were calculated before and after nebulization. Results: The investigation was successfully carried out in all volunteers. An acute or delayed allergic reaction to the aerosolized contrast medium was not observed. In 4 of 5 experiments (80%), a homogeneous signal intensity increase was readily visualized with an average signal increase of 35% after 10 minutes; in one experiment, the aerosol distribution was slightly heterogeneous. (orig.) [German] Ziel: Bestimmung der Durchfuehrbarkeit einer kernspintomographischen Darstellung der Lungenventilation mittels aerosolierter Gd-Chelate bei gesunden Probanden. Methoden: 5 Probanden (Durchschnittsalter 37 Jahre) wurden in einem 1,5T System untersucht. Die Probanden atmeten spontan aerosoliertes Gd-DTPA ueber eine Atemmaske fuer eine Dauer von 10 Minuten. Das Kontrastmittel-Aerosol wurde ueber einen leistungsfaehigen druckluftbetriebenen Vernebler generiert. Die Illustration der Ventilation erfolgte mit einer atemgegateten dynamischen T{sub 1}-gewichteten Turbo-Spin-Echosequenz. Zur Quantitifizerung der Lungenventilation wurden die Signalintensitaeten im Lungengewebe vor und nach Verneblung berechnet. Ergebnisse: Alle Untersuchungen wurden komplikationslos durchgefuehrt und beendet. Eine akute oder verzoegerte Kontrastmittelreaktion wurde nicht beobachtet. In 4 von 5

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

    Science.gov (United States)

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

    2016-02-01

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

  10. Effects of calcium chelators on calcium distribution and protein solubility in rennet casein dispersions.

    Science.gov (United States)

    McIntyre, Irene; O' Sullivan, Michael; O' Riordan, Dolores

    2016-04-15

    This study investigated the effects of calcium chelating salts on calcium-ion activity (ACa(++)), calcium distribution, and protein solubility in model CaCl2 solutions (50 mmol L(-1)) or rennet casein dispersions (15 g/100 g). Disodium phosphate and trisodium citrate at concentrations of 10 and 30 mmol L(-1) and at ratios of 1:0, 2:1, 1:1, 1:2 and 0:1 were added to both systems. The CaCl2 system, despite its simplicity, was a good indicator of chelating salt-calcium interactions in rennet casein dispersions. Adding trisodium citrate either alone or as part of a mixed chelating salt system resulted in high levels of dispersed "chelated" calcium; conversely, disodium phosphate addition resulted in lower levels, while the ACa(++) decreased with increasing concentration of both chelating salts. Neither chelating salt produced high levels of soluble protein. Thus calcium chelating salts may play a more subtle role in modulating hydration during manufacture of casein-based matrices than simply solubilising calcium or protein. PMID:26616945

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

    International Nuclear Information System (INIS)

    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

  12. 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. PMID:12475278

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

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

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

  14. Preparation of chitosan-EDTA nanoparticles and the chelating effect of radioactive strontium in vivo

    International Nuclear Information System (INIS)

    Objective: To obtain the CTS-EDTA nanoparticles and investigate their effects of chelating 89Sr2+ in vivo. Method: The CTS-EDTA nanoparticles were prepared by cross-linking CTS-EDTA with polyanion sodium tripolyphosphate ( TPP). And the zwitterionic chelate of the CTS-EDTA nanoparticles was used for promoting the radionuclides excreted in vivo. Results: The CTS-EDTA nanoparticles showed that particle size was uniformity of the spherical nano-particles by TEM, and the average particle size of 10.18 nm by Laser Particle Sizer. we found that CEC-Nano and the CEC had a good chelating effect of radioactive strontium in vivo, after 30 min and 2 h in the medication and the chelating efficiency of radioactive strontium excretion in the femur was significantly higher than the EDTA-Na2. At multiple doses,the chelating efficiency of CEC-Nano and the CEC through the urinary excretion and feces were better than traditional medicines EDTA-Na2. Conclusion: By this experimental method, we can be prepare nanodrugs of chelating radionuclide, it provides a basis for studying the broad-spectrum of radionuclide contamination chelating agents. (authors)

  15. 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.

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

    International Nuclear Information System (INIS)

    Two kinds of europium-β-diketone chelates, binary Eu(DBM)3 and ternary Eu(DBM)3phen were doped in poly(methyl methacrylate) (PMMA). These chelates show very different photoluminescent (PL) behaviors: the hypersensitive 5D0→7F2 emission bands of Eu(DBM)3phen 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 5D0 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 Eu3+ 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

  17. Physicochemical properties of skim milk powders prepared with the addition of mineral chelators.

    Science.gov (United States)

    Sikand, V; Tong, P S; Vink, Sean; Roy, Soma

    2016-06-01

    The objective of this study was to determine the effect of mineral chelator addition during skim milk powder (SMP) manufacture on the solubility, turbidity, soluble protein, and heat stability (HS). Three chelators (sodium citrate dihydrate, sodium polyphosphate, and disodium EDTA) at 3 different concentrations (5, 15, and 25mM) were added to skim milk concentrate (30% total solids), and the pH was adjusted to 6.65 before spray drying to produce SMP. Spray-dried SMP samples were tested for solubility index (SI). Additionally, samples were reconstituted to contain 9% total solids, adjusted to pH 7.0, and tested for turbidity, protein content from supernatants of ultracentrifuged samples, and HS. Lower SI values were observed for samples treated with 5mM disodium EDTA and sodium polyphosphate than control samples or samples with 5mM sodium citrate dihydrate. Furthermore, lower SI values were observed with an increased level of chelating agents regardless of chelator type. A decreased turbidity value was found with increasing levels of mineral chelating salt treatment. Low turbidity with increasing levels of added chelators may be associated with the dissociation of caseins from micelles. Furthermore, higher protein content was observed in supernatants of ultracentrifuged samples treated with increased level of chelators as compared with the control sample. Higher HS was observed in samples treated with 5mM compared with samples treated with 25mM mineral chelator. The results suggest improved solubility and HS upon addition of mineral chelators to SMP during its manufacture. PMID:27040785

  18. Highly Diastereoselective Chelation-controlled Additions to α-Silyloxy Ketones

    OpenAIRE

    Stanton, Gretchen R.; KOZ, Gamze; Walsh, Patrick J.

    2011-01-01

    The polar Felkin-Anh, Cornforth, and Cram-chelation models predict that the addition of organometallic reagents to silyl–protected α–hydroxy ketones proceeds via a non-chelation pathway to give anti-diol addition products. This prediction has held true for the vast majority of additions reported in the literature and few methods for chelation-controlled additions of organometallic reagents to silyl–protected α–hydroxy ketones have been introduced. Herein, we present a general and highly diast...

  19. Thermodynamic study of chelation of rare earth(III) ions with 2,3-dihydroxynaphthalene (DON)

    International Nuclear Information System (INIS)

    The chelation of 2,3-dihydroxynaphthalene with trivalent La, Pr, Nd, Sm, Gd, Tb, Dy, Ho and Y has been studied pH-metrically at 30deg +- 0.5deg in aqueous ethanol (10% v/v) at different ionic concentrations (0.05, 01, 0.15 and 0.2M KNO3). Formation of 1:1 chelates are indicated. The order of stability is found to be Ho > Dy > Tb > Y> Gd > Sm > Nd > Pr > La. The thermodynamic stability constants and free energies of chelation have been reported. (author)

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

    International Nuclear Information System (INIS)

    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)

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

    International Nuclear Information System (INIS)

    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

  2. [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).

  3. (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).

  4. Guidelines on iron chelation therapy in patients with myelodysplastic syndromes and transfusional iron overload.

    Science.gov (United States)

    Gattermann, Norbert

    2007-12-01

    Experts believe that iron overload is an important problem which could be avoided with suitable treatment. Guidelines on treating myelodysplastic syndromes (MDS) include sections on using iron chelation therapy to prevent or ameliorate transfusional iron overload. The proportion of MDS patients who may benefit from iron chelation therapy is 35-55%, depending on the length of survival necessary for iron to accumulate to a detrimental level. Candidates for iron chelation are mainly patients with dyserythropoietic and cytopenic subtypes of disease, which fall into the International Prognostic Scoring System (IPSS) Low-risk or Intermediate-1-risk categories, with median survival of 3-6 years. PMID:18037413

  5. Radioactive europium-chelate-based silica nanoparticles as a probe for stability, incorporation efficiency and trace analysis

    International Nuclear Information System (INIS)

    Two luminescent terbium and europium lanthanide chelates were efficiently embedded into silica nanoparticles by using a reverse microemulsion process. The incorporation was achieved without covalent bonding between the lanthanide chelates and the silica matrix. To investigate the efficiency of the incorporation process and the stability of the silica encapsulated lanthanide complex, a method based on a radioactive probe was developed; γ-emitting europium (152) chelates were synthesized and incorporated into silica nano-particles. Measurements of the γ activity through the entire synthesis allowed the accurate characterization of the incorporation efficiency of the used chelates. A clear correlation was established between the physicochemical properties of the different chelates and the measured incorporation efficiencies. A very efficient noncovalent incorporation of lanthanide chelates in highly stable nanoparticles was achieved by tuning the chelate properties, thus rendering the development of lanthanide-based fluorescent nanoparticles easier. (authors)

  6. Chelating water-soluble polymers for waste minimization

    International Nuclear Information System (INIS)

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

  7. Chelation therapy of thorium deposited in rat lung

    International Nuclear Information System (INIS)

    The effect of calcium diethylenetriaminepentaacetate (CaDTPA) and a siderophore analogue 3,4,3-LI(1,2-HOPO) on decorporation of small and large thorium masses (234Th 46 ng, 234Th 46 ng + 232Th 5 μg per rat) instilled into the lungs was studied. Along with repeated injections, chelating agents were administered continuously by mini-osmotic pumps over 14 d. Treatment with CaDTPA alone was partly successful in the decorporation of both thorium masses. Greater decorporation was achieved with 3,4,3-LI(1,2-HOPO) in pumps and CaDTPA in injections. In the whole body, lungs and skeleton, 23%, 24% and 24% of control radioactivity was found, respectively, for the small mass of thorium. When the large mass of thorium was instilled, only continuous infusion of 3,4,3-LI(1,2-HOPO) at low concentration efficiently prevented transfer of thorium to the skeleton (reduced to 9% of control). Both the whole body and lungs retained 50% of control radioactivity. (author)

  8. New method to estimate stability of chelate complexes

    CERN Document Server

    Grigoriev, F V; Romanov, A N; Kondakova, O A; Sulimov, V B

    2009-01-01

    A new method allowing calculation of the stability of chelate complexes with Mg2+ ion in water have been developed. The method is based on two-stage scheme for the complex formation. The first stage is the ligand transfer from an arbitrary point of the solution to the second solvation shell of the Mg2+ ion. At this stage the ligand is considered as a charged or neutral rigid body. The second stage takes into account disruption of coordinate bonds between Mg2+ and water molecules from the first solvation shell and formation of the bonds between the ligand and the Mg2+ ion. This effect is considered using the quantum chemical modeling. It has been revealed that the main contribution to the free energy of the complex formation is caused by the disruption/formation of the coordinate bonds between Mg2+, water molecules and the ligand. Another important contribution to the complex formation energy is change of electrostatic interactions in water solvent upon the ligand binding with Mg2+ ion. For all complexes under...

  9. The phospholipid vesicles coating on metal chelated inorganic surfaces

    International Nuclear Information System (INIS)

    This work showed the formation of phospholipid vesicle coating on inorganic sericite surface with characterization by combining electron microscopy of FE-SEM, TEM, AFM, and qualitatively evaluated the coated phospholipid vesicle by XPS as a function of etching time. The possibility of phospholipid vesicle mobility on the surface was restrained by the chelation effect of magnesium cation. The stabilization properties of phospholipid vesicles on sericite surface were demonstrated by the various concentration of magnesium cation. The presence of magnesium was found to have a much more pronounced influence on the lipid deposition process. The Mg cation plays an important role for attaching the phospholipids with optimum concentration of 7 mM. Totally, the phospholipid vesicles coating on inorganic powder could be useful for bio-related fields such as cosmetics and drug delivery system as the key functional compounds. We hope this basic result lead to a general and simple approach to prepare a wide a range of controlled releasing materials including an encapsulation with cosmetics or drugs

  10. The iron chelator desferrioxamine attenuates postischemic ventricular dysfunction

    International Nuclear Information System (INIS)

    Recent evidence suggests that postischemic myocardial dysfunction (stunning) may be mediated by oxygen free radicals, but the mechanism by which they produce myocellular damage remains unknown. Since iron catalyzes formation of hydroxyl radicals (HO·) as well as HO·-initiated lipid peroxidation, the authors explored the potential role of this metal in the pathogenesis of myocardial stunning. Open-chest dogs undergoing a 15-min occlusion of the left anterior descending coronary artery (LAD) followed by 4 h of reperfusion (REP) received the iron chelator desferrioxamine intravenously or normal saline. Regional myocardial function was assessed by measuring systolic wall thickening with an epicardial Doppler probe. The two groups exhibited comparable systolic thickening under base-line conditions and similar degrees of dyskinesis during ischemia. After REP, however, recovery of contractile function as considerably greater in desferrioxamine-treated compared with control dogs. These differences could not be ascribed to hemodynamic factors. The results suggest that iron-catalyzed reactions (possibly HO· generation) play a significant role in myocardial stunning after a brief episode of reversible regional ischemia

  11. Lanthanide complexes of an oxazoline-phenoxide hybrid chelate

    International Nuclear Information System (INIS)

    The synthesis of 2-(2'-hydroxy-3'-allylphenyl)-4,4-dimethyl-2-oxazoline, H-Allox (3), and lanthanide tris chelate complexes, mer-Ln(Allox)3 (Ln = La (4), Ce (5), Sm (6), Er (7), and Y (8)), derived from it are reported. A six-coordinate mer geometry without alkene coordination was confirmed in the solid state by X-ray crystallography for 5 and 7. Variable-temperature NMR experiments suggested that this is the most stable isomer in solution as well, although the inequivalent ligand environments undergo rapid averaging at room temperature for all five complexes. A mechanistic investigation indicated that this fluxional process is an intramolecular six-coordinate rearrangement, but it was not possible to distinguish between a Bailar (trigonal) or Ray-Dutt (rhombic) twist. Kinetic parameters for the fluxional process were determined by line shape analysis for 8 yielding ΔH = 24 ± 2 kJ mol-1 and ΔS = -99 ± 10 J mol-1 K-1. The structural and dynamic features of 4-8 were compared with the related In, Ga, and Al tris(2-oxazolylphenoxides). (author)

  12. Multidentate dipyridyl derivatives as chelates for rhenium (V)

    International Nuclear Information System (INIS)

    Rhenium (V) complexes with the following multidentate dipyridyl ligands were prepared: 2,2'-dipyridylamine (DPA), 1,2-bis(2-pyridyl)ethylene (DPE) and di-(2-picolyl)amine (HDIPA). Reactions of a twofold molar excess of the potentially NN donor ligand DPA with trans-[ReO (OEt)Cl2(PPh3)2] in ethanol led to isolation of a monomer [ReOCl2(OEt)(DPA)] (1). Treatments of trans-[ReOCl3(PPh3)2] with a tenfold molar excess of DPA in ethanol at reflux yielded [ReO2(dpa)2]Cl (2), but with a twofold molar excess a dimer (μ-O)[{ReOCl2(dpa)}2] (3a) was isolated. The latter reaction with (n-Bu4N)[ReOCl4] as starting material in ethanol at room temperature led to a dark green product, also with the formulation (μ-O)[{ReOCl2(dpa)}2] (3b). Reacting equimolar quantities of (n-Bu4N)[ReOCl4] and HDIPA in acetone led to [ReOCl(OH2)(DIPA)Cl (4) in which HDIPA acted as a monoanionic terdentate chelate. The reaction of trans-[ReOCl3(PPh3)2] with DPE, in which DPE undergoes a metal-promoted nucleophilic attack by a water molecule, produces a complex with a general formula [ReO(DPE.OH)Cl2] (5). (author)

  13. MR imaging of lung ventilation with aerosolized Gadolinium-chelates

    International Nuclear Information System (INIS)

    Purpose: To evaluate the feasibility of magnetic resonance assessment of human lung ventilation with aerosolized Gd-chelates in healthy volunteers. Materials and Methods: Five healthy adults (mean age 37 years) were studied with a 1.5 T unit. The volunteers were instructed to inhale the aerosol through an airtight facial mask for 10 minutes. The aerosol was generated with a jet-type small particle nebulizer with attached heater. Ventilation imaging was performed using a respiration-gated dynamic T1-weighted turbo spin echo sequence (TR=199 ms, TE=8.5 ms, 12 signal averages, slice thickness 10 mm). Pulmonary signal intensity changes were calculated before and after nebulization. Results: The investigation was successfully carried out in all volunteers. An acute or delayed allergic reaction to the aerosolized contrast medium was not observed. In 4 of 5 experiments (80%), a homogeneous signal intensity increase was readily visualized with an average signal increase of 35% after 10 minutes; in one experiment, the aerosol distribution was slightly heterogeneous. (orig.)

  14. Removal of Some Chelators from Aqueous Solutions Using Polymeric Ingredients

    International Nuclear Information System (INIS)

    This work tries to throw a light on the removal of thenoyl trifluoroacetone (TTA) and ethylene diamine tetraacetic acid (EDTA), extractants extensively used in many nuclear facilities, from aqueous solutions under different experimental conditions using Amberlite XAD resins. The applied resins exhibit high retention ability for the studied chelators with a maximum sorption capacity has the values of 23.9 and 38.0 mgg-1 for sorption of TTA and EDTA on Amberlite XAD4 and 18.6 and 21.2 mgg-1 for their sorption of on Amberlite XAD7. Factors affecting the resin retention ability such as ph value of aqueous solution and presence of co solvent have been studied. The kinetics of sorption behavior, in the applied system, indicate the process to be controlled by more than one diffusion mechanism. Therefore, two diffusion models were utilized to understand and verify the mechanism of sorption processes; they are the film mass transfer model and the interparticle diffusion model. The first model, based on film resistance, gave a successful depiction for sorption of TTA onto Amberlite XAD4 and XAD7 and the second one displayed an acceptable prediction for sorption of EDTA onto Amberlite XAD4

  15. Mechanisms of oxide dissolution by acid chelating agents

    International Nuclear Information System (INIS)

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

  16. Thiophene-based ligands as potential new metal ion chelation units in nuclear medicine

    International Nuclear Information System (INIS)

    An effort to explore new metal chelation units for radiopharmaceutical metal ion chelation applications has led us to the 2,5-dialkylamide-3,4-dihydroxythiophene type chelators. The ligand synthesis allows for facile asymmetric substitution that produces the amide-ester. Also, the monobenzyl derivative was obtained and structurally characterized in the P-1 space group with unit cell dimensions a = 10.111(3) A, b 11.761(3) A, c = 12.014(3) A , α = 72.987(5) .deg., β = 88.576(5) .deg., γ = 71.441(5) .deg., V = 1291.3(6) A3, Z = 2. The asymmetric hydrogen bonding pattern suggests the alternative salicylate-type metal chelation is accessible

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

    Science.gov (United States)

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

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

    Science.gov (United States)

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

  19. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Droege, P.

    1997-03-01

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

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

    International Nuclear Information System (INIS)

    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)

  2. Serum stability of 67Cu chelates: comparison with 111In and 57Co

    International Nuclear Information System (INIS)

    Simple chelates and chelate conjugated monoclonal antibodies labeled with 111In, 57Co and 67Cu demonstrate marked differences in stability when exposed to a serum environment. Among these radiometals, on DTPA, the order of stability is 111In > 57Co >> 67Cu. On benzyl-EDTA, the order of stability is 111In approx. 57Co >> 67Cu. Among those investigated, the only serum stable 67Cu chelate found was 67>Cu-TETA. The order of stability observed for 57Co vs 67Cu is contrary to published equilibrium constants. These in vitro studies suggest that the in vivo behavior of metal chelates exposed to a complex molecular environment may not be predicted by classically determined equilibrium constants. (author)

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

    International Nuclear Information System (INIS)

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

  4. Effect of chelating agents on the transport of radioactive solutes in subsurface porous media

    International Nuclear Information System (INIS)

    The effect of chelating agents on the transport of radioactive solutes in subsurface porous media is analyzed by formulating an advective-dispersive transport model which incorporates chelate formation, adsorption, decay, and degradation of transporting radioactive solutes. The governing equations are formulated by introducing the concept of a tenad. Particularly the governing equation for the tenad of a radioactive solute, is presented as a linear partial differential form and solved analytically by introducing an extended concept of distribution coefficient, KD. The calculated results from the model show that the transport rate of the tenad of a chelating agent, is much greater than that of the tenad. This faster transport of may be due to the low retardation factor of comparing to that of. Therefore, it is concluded that presence of chelating agents even in a small amount greatly accelerates the transport of radioactive wastes from a geologic radioactive waste repository

  5. The Management of Iron Chelation Therapy: Preliminary Data from a National Registry of Thalassaemic Patients

    Directory of Open Access Journals (Sweden)

    Adriana Ceci

    2011-01-01

    Full Text Available Thalassaemia and other haemoglobinopathies constitute an important health problem in Mediterranean countries, placing a tremendous emotional, psychological, and economic burden on their National Health systems. The development of new chelators in the most recent years had a major impact on the treatment of thalassaemia and on the quality of life of thalassaemic patients. A new initiative was promoted by the Italian Ministry of Health, establishing a Registry for thalassaemic patients to serve as a tool for the development of cost-effective diagnostic and therapeutic approaches and for the definition of guidelines supporting the most appropriate management of the iron-chelating therapy and a correct use of the available iron-chelating agents. This study represents the analysis of the preliminary data collected for the evaluation of current status of the iron chelation practice in the Italian thalassaemic population and describes how therapeutic interventions can widely differ in the different patients' age groups.

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

    International Nuclear Information System (INIS)

    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)

  7. Simultaneous measurement of NK cell cytotoxicity against two target cell lines labelled with fluorescent lanthanide chelates.

    Science.gov (United States)

    Lövgren, J; Blomberg, K

    1994-07-12

    We describe a cytotoxicity assay which permits the simultaneous measurement of natural killer cell activity against two different cell lines. The target cell lines are labelled either with a fluorescent europium chelate or with a fluorescent terbium chelate and cell death is quantified by measuring the chelate release. K-562, Molt4 and Daudi cell lines have been used as targets. The release of the two chelates from the target cells can be detected with the help of time resolved fluorometry. As the measurements are made after background fluorescence has decayed no additional steps are needed to correct for the background from the medium. The assay procedure used for measurement of cytotoxicity against two target cell lines is very similar to the widely used 51Cr release assay. PMID:8034979

  8. 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.

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

    Institute of Scientific and Technical Information of China (English)

    Wangying; WangHongzuo; 等

    1995-01-01

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

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

    International Nuclear Information System (INIS)

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

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

    OpenAIRE

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

    2012-01-01

    A series of compounds that target reactive transition metal chelates to somatic Angiotensin Converting Enzyme (sACE-1) have been synthesized. Half maximal inhibitory concentrations (IC50) and rate constants for both inactivation and cleavage of full length sACE-1 have been determined and evaluated in terms of metal-chelate size, charge, reduction potential, coordination unsaturation, and coreactant selectivity. Ethylenediamine-tetraacetic acid (EDTA), nitrilotriacetic acid (NTA), 1,4,7,10-tet...

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

    OpenAIRE

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

    2011-01-01

    A series of compounds that target reactive metal-chelates to the HIV-1 Rev Response Element (RRE) mRNA have been synthesized. Dissociation constants and chemical reactivity toward HIV RRE RNA have been determined and evaluated in terms of reduction potential, coordination unsaturation, and overall charge associated with the metal-chelate-rev complex. Ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), diethylenetriaminepentaacetic acid (DTPA), and 1,4,7,10-tetraazacyclo-dodec...

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

    OpenAIRE

    Evangeli, M.; Mughal, K.; Porter, J. B.

    2010-01-01

    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 be...

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

    OpenAIRE

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

    2010-01-01

    We previously reported Zn2+ chelation improved recovery of synaptic potentials after transient oxygen and glucose deprivation in brain slices. Such an effect could be due to reduced accumulation of Zn2+ in postsynaptic neurons, or could also be due to prevention of the onset of spreading depression-like events. A combination of optical and electrical recording was used here to demonstrate that Zn2+ chelation is effective because it delays spreading depression-like events. If the duration of o...

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

    OpenAIRE

    Frumkin, H; Manning, C C; Williams, P. L.; Sanders, A; Taylor, B.B.; Pierce, M; Elon, L; Hertzberg, V S

    2001-01-01

    Chelation challenge testing has been used to assess the body burden of various metals. The best-known example is EDTA challenge in lead-exposed individuals. This study assessed diagnostic chelation challenge with dimercaptosuccinic acid (DMSA) as a measure of mercury body burden among mercury-exposed workers. Former employees at a chloralkali plant, for whom detailed exposure histories were available (n = 119), and unexposed controls (n = 101) completed 24-hr urine collections before and afte...

  16. Role of chelating agent in chemical and fluorescent properties of SnO2 nanoparticles

    Science.gov (United States)

    He, Shao-Bo; Wang, Shi-Fa; Ding, Qing-Ping; Yuan, Xiao-Dong; Zheng, Wan-Guo; Xiang, Xia; Li, Zhi-Jie; Zu, Xiao-Tao

    2013-05-01

    A modified Polyacrylamide gel route is applied to synthesize SnO2 nanoparticles. High-quality SnO2 nanoparticles with a uniform size are prepared using different chelating agents. The average particle size of the samples is found to depend on the choice of the chelating agent. The photoluminescence spectrum detected at λex = 230 nm shows a new peak located at 740 nm due to the surface defect level distributed at the nanoparticle boundaries.

  17. Metal Extraction From Soil Samples By chelation in a Microwave System

    OpenAIRE

    Chatreewongsin, Urai

    2000-01-01

    This work involves the combination of chelation and microwave extraction as a technique for extracting adsorbed metals in soil. It has been termed in this work, Chelate Assisted Microwave Extraction (CAME). Unlike other extraction methods, CAME is able to differentiate between anthropological and geological trace metals. The method has been applied to major sample matrices included three types of soils (Bertie Sandy Loam, Davidson Silty Clay, and Davidson Clayey Loam) as well as se...

  18. The Role of Chelation in the Treatment of Arsenic and Mercury Poisoning

    OpenAIRE

    Kosnett, Michael J

    2013-01-01

    Chelation for heavy metal intoxication began more than 70 years ago with the development of British anti-lewisite (BAL; dimercaprol) in wartime Britain as a potential antidote the arsenical warfare agent lewisite (dichloro[2-chlorovinyl]arsine). DMPS (unithiol) and DMSA (succimer), dithiol water-soluble analogs of BAL, were developed in the Soviet Union and China in the late 1950s. These three agents have remained the mainstay of chelation treatment of arsenic and mercury intoxication for mor...

  19. Production of siderophore type chelates in Atlantic Ocean waters enriched with different carbon and nitrogen sources

    OpenAIRE

    Mawji, Edward; Gledhill, M.; Milton, J.A.; M. V. Zubkov; Thompson, Anu; Wolff, George A.; Achterberg, Eric P.

    2011-01-01

    Siderophore type chelates were detected in nutrient enriched, incubated seawater collected from different biogeographical regions of the Atlantic Ocean. Seawater was enriched with glucose and ammonium, glycine (as a source of carbon and nitrogen) or chitin and ammonium at different concentrations and incubated for up to 3 – 4 days in the dark. Siderophore type chelates were detected using high performance liquid chromatography coupled to inductively coupled plasma mass spectrometry (HPLC-ICP-...

  20. ORGANIC CHELATING REAGENT ON REDOX ADSORPTION OF ACTIVATED CARBON FIBER TOWARDS Au3+

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Organic chelating reagent influences upon the redox adsorption of activated carbon fibertowards Au3- were systematically investigated. The experimental results indicated that the presenceof organic chelating reagent on activated carbon fiber strongly affects adsorption capacity ofactivated carbon fiber towards Au3+. The reduction-adsorption amount of Au3+ increased three timesby the presence of 8-quinolinol. Furthermore, The reduction-adsorption amount of Au3+ depended onthe pH value of adsorption and temperature.

  1. Intracellular reduction/activation of a disulfide switch in thiosemicarbazone iron chelators

    OpenAIRE

    Akam, Eman A.; Chang, Tsuhen M.; Astashkin, Andrei V.; Tomat, Elisa

    2014-01-01

    Iron scavengers (chelators) offer therapeutic opportunities in anticancer drug design by targeting the increased demand for iron in cancer cells as compared to normal cells. Prochelation approaches are expected to avoid systemic iron depletion as chelators are liberated under specific intracellular conditions. In the strategy described herein, a disulfide linkage is employed as a redox-directed switch within the binding unit of an antiproliferative thiosemicarbazone prochelator, which is acti...

  2. Europium(III)-chelates embedded in nanoparticles are protected from interfering compounds present in assay media

    International Nuclear Information System (INIS)

    Lanthanide chelates are excellent labels in ligand binding assays due to their long lifetime fluorescence, which enables efficient background reduction using time-resolved measurement. In separation-free homogeneous assays, however, some compounds in the sample may cause quenching of the lanthanide fluorescence and extra steps are required before these samples can be measured. In this study we have evaluated whether europium chelates packed inside a polystyrene nanoparticle are better protected from the environment than individual Eu(III)-chelates, and do these particles have higher tolerance against known interfering compounds (bivalent metal ions and variation of pH). We also tested whether metal ions had any effect on a fluorescence resonance energy transfer (FRET) based detection of a bioaffinity binding reaction. The presence of metal ions or variation of pH did not affect the fluorescence of the Eu(III)-chelate dyed nanoparticles, while significant decrease of the fluorescence was detected with a 9-dentate Eu(III)-chelate. Metal ions also decreased the fluorescence lifetime of the 9-dentate Eu(III)-chelate from 0.960 to 0.050 ms. Coloured metal ions caused a minor decrease in sensitised emission generated by FRET when Eu(III)-chelate dyed nanoparticles were used as donor labels. The decreased signal was due to the absorption of the sensitised emission by the coloured metal ions, since the metal ions had no effect on the lifetime of the sensitised emission. Thus the Eu(III)-chelate dyed nanoparticles are preferred labels in homogeneous bioaffinity assays, when interfering compounds are known to be present

  3. Curcumin, a cancer chemopreventive and chemotherapeutic agent, is a biologically active iron chelator

    OpenAIRE

    Jiao, Yan; Wilkinson, John; Di, Xiumin; Wang, Wei; Hatcher, Heather; Kock, Nancy D.; D'Agostino, Ralph; Knovich, Mary Ann; Torti, Frank M; Suzy V Torti

    2009-01-01

    Curcumin is a natural product currently in human clinical trials for a variety of neoplastic, preneoplastic, and inflammatory conditions. We previously observed that, in cultured cells, curcumin exhibits properties of an iron chelator. To test whether the chelator activity of curcumin is sufficient to induce iron deficiency in vivo, mice were placed on diets containing graded concentrations of both iron and curcumin for 26 weeks. Mice receiving the lowest level of dietary iron exhibited borde...

  4. Diamond burr superficial keratectomy in the treatment of visually-significant anterior corneal lesions Ceratectomia superficial com broca de diamante no tratamento de lesões anteriores da córnea

    Directory of Open Access Journals (Sweden)

    João Baptista Nigro Santiago Malta

    2008-06-01

    Full Text Available PURPOSE: To evaluate the efficacy and safety of diamond burr superficial keratectomy in the treatment of visually-significant anterior corneal lesions. METHODS: A retrospective review of 23 eyes (23 patients. Pre- and postoperative visual acuities and refractions, slit-lamp biomicroscopic findings, and the incidence of recurrence of disease after keratectomy were studied. RESULTS: Nineteen eyes had map-dot-fingerprint basement membrane dystrophy and 4 had Salzmann's nodular degeneration. All patients presented with decreased vision, as well as varying degrees of glare, halos, and monocular diplopia. Postoperative follow-up ranged from 3 to 39 months (mean 10.6 months, and no recurrence of the original disease occurred within this period. This procedure improved the best-corrected visual acuity from 20/36 (LogMar 0.250 to 20/24 (LogMar 0.076 by LogMar statistical evaluation (pOBJETIVO: Avaliar a eficácia e segurança da ceratectomia superficial com broca de diamante no tratamento das lesões anteriores da córnea. MÉTODOS: Foi realizado estudo retrospectivo de 23 olhos de 23 pacientes. Foram avaliados acuidade visual e refração pré e pós-operatório, biomicroscopia e incidência de recorrência da doença após ceratectomia. RESULTADOS: Dos 23 olhos avaliados, 19 olhos apresentavam distrofia da membrana basal (map-dot-fingerprint e 4 degeneração nodular de Salzmann. Todos os pacientes apresentavam diminuição da acuidade visual, assim como graus variados de ofuscamento, halos e diplopia monocular. O seguimento pós-operatório variou entre 3 e 39 meses (média de 10,6 meses e não houve recorrência da doença original nesse período. O procedimento melhorou a acuidade visual com melhor correção de 20/36 (LogMar 0,250 para 20/24 (LogMar 0,076 com p<0,001. Em relação as mudanças refracionais não houve significância (p=0,232 sendo o equivalente esférico pré-operatório de - 0,36 ± 2,28DE e pós-operatório de -0,71 ± 2,26DE. As

  5. Ethyl acetoacetate ligand distribution in the course of titanium n-butoxide chelation

    International Nuclear Information System (INIS)

    Sols obtained by chelation of titanium n-butoxide with ethyl acetoacetate, Eaa, in various ratios have been subjected to FTIR, 1H and 13C NMR, HSQC and UV–Vis spectroscopy in order to provide insight in the compounds obtained, their structure and quantitative relationships. Three compounds, the bis-chelated monomer, Ti(OnBu)2(Eaa)2, bis-chelated dimer, (Ti(OnBu)3Eaa)2 and monochelated dimer, Ti2(OnBu)7Eaa have been established. As the molar ratio Eaa/Ti(OnBu)4 increases, the coordination changes from the monochelated and bis-chelated dimer to the bis-chelated monomer. Additionally, the transesterification reaction, influencing the chemical composition of the compounds was noted. The hydrolysis of the prepared sols was partial, leaving some residual butoxy and ethyl acetoacetate groups attached to titanium. Thermal treatment of the prepared amorphous gels at 350 °C yielded with the formation of nanocrystalline anatase. It was noted that high Eaa/Tnb ratio slightly retards the anatase formation. - Highlights: • Titanium n-butoxide was modified with ethyl acetoacetate in various ratios. • Among other chelate phases, previously undescribed Ti2(OnBu)7Eaa was obtained. • NMR-based mass balance procedure was introduced to obtain quantitative relationships. • The transesterification reaction has been noted. • Nanocrystalline anatase has been obtained by thermal treatment at 350 °C

  6. Synthesis and Characterization of polyacrylamide Chelating Resin with Thenoyltrifluoroacetone for Separation of Thorium from Uranium

    International Nuclear Information System (INIS)

    New effective chelating resin is synthesized by immobilization of Thenoyltrifluoroacetone (HTTA) on cross linked polyacrylamide. The chelating exchanger is used for separation of uranium (UO22+) and thorium(Th4+). The analyzed metal ions were quantitatively measured by ion chromatographic technique coupled with UV/V is detector and derivatization reaction of Arsenazo(III) at wavelength 660 nm. Different factors affecting the metal ions uptake and hence the separation efficient c y of the chelating polyacrylamide resin were investigated. Optimization of conditions showed that maximum uptake of UO22+ and Th4+ are at ph 4.0 and 3.0 respectively. Isothermal capacity shows a relatively high capacity of the chelating resin towards divalent uranium more than that of tetravalent thorium. The capacity of the chelating resin for UO22+ and Th4+ was found to be 0.05 and 0.034 mmol/gm, respectively. Separation of UO22+ and Th4+ was successively performed using column chromatographic technique loaded with the chelating resin. The retained metal ions were sequentially separated by i socratic elution using 0.1 M HNO3

  7. The antibody-linked chelating polymers for nuclear therapy and diagnostics

    International Nuclear Information System (INIS)

    This review deals with the problem of protein modification with chelating polymers. The main purpose of this approach is the preparation of monoclonal antibodies labeled with heavy metal isotopes (α-, β-, and δ-emitting metals and metals used for NMR-tomography). Traditional binding of metals with proteins via chelating agents directly coupled to protein molecule does not allow binding a high number of metal atoms per single protein molecule and can also alter protein specific properties. At the same time, metal-to-protein binding via intermediate chelating polymer makes possible the binding of several dozen metal atoms per single protein without affecting its specific properties. Moreover, the variations in polymer properties and molecular weight allow controlled modified antibody biodistribution and clearance rate. Modified antibodies can be used successfully for nuclear and NMR diagnostics and for nuclear therapy. The following problems are discussed: the chemistry of the coupling of chelating groups to polymer backbone; the binding of chelating polymers to proteins, including monoclonal antibodies; the ability of chelating polymer-to-protein conjugates to bind heavy metals; the influence of the modification on protein conformation and specific properties; the behavior of metal-containing conjugates in vivo; the practical use of conjugates obtained for radioimmunoimaging, radioimmunotherapy, NMR-tomography, and in vitro immunoassays. Future prospects of the approach are also discussed.101 references

  8. Chelate chase of radiopharmaceuticals reversibly bound to monoclonal antibodies improves dosimetry

    International Nuclear Information System (INIS)

    One hundred micrograms of monoclonal antibody (MoAb) CHA 255 with a binding constant Kb of 4 x 109 was complexed with indium-111 labeled BLEDTA II, GLEDTA IV, benzyl EDTA, and an EDTA conjugate of Fab. The 24-hour tumor and organ distribution in BALB/c mice bearing KHJJ tumors was studied for each compound alone, the antibody complex, and 3 hours following a chelate chase of the antibody complex. Whole-body biological half-life was measured for 7 days with and without a chelate chase for each antibody complex. The 24-hour whole-body counts dropped 20-60% within 3 hours of administering the chelate chase. Blood concentration fell over 89% within 3 hours of administering the chase and there was a decrease in concentration in all organs, except the kidneys, of 10 to 85%. Theoretical equivalent human doses were calculated from the 24-hour organ concentrations, effective half-life, and MIRD 11 S values (absorbed dose per cumulated activity). Liver and spleen were the target organs, with the dose ranging from 0.50 to 3.91 rads per millicurie. The reduction in organ radiation dose varied up to 95% following the chelate chase. Rapid selective renal clearance of chelate labeled radiopharmaceuticals by competitive inhibition (chelate chase) of their reversible binding to monoclonal antibodies, greatly improves the radiation dosimetry of tumor imaging agents. 28 references, 5 figures, 5 tables

  9. Wood impregnated with metal chelates dissolved in organic media tested for termite resistance

    Directory of Open Access Journals (Sweden)

    Lara Maistrello

    2011-08-01

    Full Text Available Wood manufactured products are subjected to biological decay due to fungi and insects. The use of copper chelates as biocides was proposed, due to their high stability which minimizes copper leaching into the environment. Considering the remarkable effectiveness showed by copper chelates on brown rot fungi, zinc and copper salicylate complexes were prepared in order to have metal chelates soluble in organic media available. The present study aimed at evaluating these metal chelates complexes as preservative agents for wood treatment against termites. Trials were performed on Reticulitermes lucifugus (Rossi and Kalotermes flavicollis (Fabricius. Results showed that in both termite species wood consumption was significantly lower on Cu-chelates treated samples compared to untreated wood, whereas the wood slices impregnated with Zn-chelates and the organic media alone gave an intermediate response. Interestingly, in one case solvent-impregnated wood was significantly more attractive than untreated wood for both species and further investigations are being carried out to clarify this behaviour.

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

    International Nuclear Information System (INIS)

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

  11. Translational downregulation of HSP90 expression by iron chelators in neuroblastoma cells.

    Science.gov (United States)

    Sidarovich, Viktoryia; Adami, Valentina; Gatto, Pamela; Greco, Valentina; Tebaldi, Toma; Tonini, Gian Paolo; Quattrone, Alessandro

    2015-01-01

    Iron is an essential cellular nutrient, being a critical cofactor of several proteins involved in cell growth and replication. Compared with normal cells, neoplastic cells have been shown to require a greater amount of iron, thus laying the basis for the promising anticancer activity of iron chelators. In this work, we evaluated the effects of molecules with iron chelation activity on neuroblastoma (NB) cell lines. Of the 17 iron chelators tested, six reduced cell viability of two NB cell lines with an inhibition of growth of 50% below 10 µM; four of the six molecules-ciclopirox olamine (CPX), piroctone, 8-hydroxyquinoline, and deferasirox-were also shown to efficiently chelate intracellular iron within minutes after addition. Effects on cell viability of one of the compounds, CPX, were indeed dependent on chelation of intracellular iron and mediated by both G0/G1 cell cycle block and induction of apoptosis. By combined transcriptome and translatome profiling we identified early translational downregulation of several members of the heat shock protein group as a specific effect of CPX treatment. We functionally confirmed iron-dependent depletion of HSP90 and its client proteins at pharmacologically achievable concentrations of CPX, and we extended this effect to piroctone, 8-hydroxyquinoline, and deferasirox. Given the documented sensitivity of NB cells to HSP90 inhibition, we propose CPX and other iron chelators as investigational antitumor agents in NB therapy. PMID:25564462

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

    Science.gov (United States)

    Jagetiya, Bhagawatilal; Sharma, Anubha

    2013-04-01

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

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

    International Nuclear Information System (INIS)

    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.)

  14. Chelation of intracellular calcium blocks insulin action in the adipocyte

    Energy Technology Data Exchange (ETDEWEB)

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

    1987-02-01

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

  15. Chelation of intracellular calcium blocks insulin action in the adipocyte

    International Nuclear Information System (INIS)

    The hypothesis that intracellular Ca2+ is an essential component of the intracellular mechanism of insulin action in the adipocyte was evaluated. Cells were loaded with the Ca2+ chelator quin-2, by preincubating them with quin-2 AM, the tetrakis(acetoxymethyl) ester of quin-2. Quin-2 loading inhibited insulin-stimulated glucose transport without affecting basal activity. The ability of insulin to stimulate glucose uptake in quin-2-loaded cells could be partially restored by preincubating cells with buffer supplemented with 1.2 mM CaCl2 and the Ca2+ ionophore A23187. These conditions had no effect on basal activity and omission of CaCl2 from the buffer prevented the restoration of insulin-stimulated glucose uptake by A23187. Quin-2 loading also inhibited insulin-stimulated glucose oxidation and the ability of insulin to inhibit cAMP-stimulated lipolysis without affecting their basal activities. Incubation of cells with 100 μM quin-2 or quin-2 AM had no effect on intracellular ATP concentration or the specific binding of 125I=labeled insulin to adipocytes. These findings suggest that intracellular Ca2+ is an essential component in the coupling of the insulin-activated receptor complex to cellular physiological/metabolic machinery. Furthermore, differing quin-2 AM dose-response profiles suggest the presence of dual Ca2+-dependent pathways in the adipocyte. One involves insulin stimulation of glucose transport and oxidation, whereas the other involves the antilipolytic action of insulin

  16. Development of chelate tagging method of protein at low temperature

    International Nuclear Information System (INIS)

    This study aimed at development of a protein labelling method at a low temperature, available for functional proteins, such as antibodies and enzymes mostly unstable at high temperatures. A solution of anti-mouse IgG antibody added with EDTA was incubated with 51CrCl3 at 4degC for 24 hours. After stopping the reaction with 100-fold amount of EDTA-2Na, the solution was fractionated into antibody fraction and metal fraction by HPLC. After incubation, non-specific Cr adsorption on the antibody in no relation to the chelate reagent was chased with 10-fold amount of CrCl3. To remove free Cr, the sample solution was incubated with 10 to 50-fold ICB-EDTA solution containing N,N-dimethyl-formamide. Then, the amount of Cr-labelling on the antibody was determined. In Western-blotting, chick actin was applied onto SDS-polyacrylamide gel electrophoresis. One part of the lane was stained with brilliant-blue and the other was transferred on nitrocellulose membrane by semi-dry method and stained with panceau-S. Anti-actin monoclonal antibody and anti-mouse IgG antibody were used as the first antibody and the second one, respectively. When incubated with ICB-EDTA for 3 days, labelling reached the maximum level. Although labelling of the second antibody was performed with maleimido-C3-benzyl EDTA and 45Ca as a substitute for 51Cr, the rate of labelling was lower than the rate for a combination of ICB-EDTA and 51Cr. Autoradiography of the anti-mouse IgG preparation after SDS-acrylamide gel electrophoresis revealed that radioactivity was detected on the site of H-chain but not L-chain. This indicates that 51Cr labelling of protein is stable even under the conditions of SDS denaturation. (M.N.)

  17. Resinas quelantes amidoxímicas Amidoxime chelating resins

    Directory of Open Access Journals (Sweden)

    Fernanda M. B. Coutinho

    1999-12-01

    Full Text Available Resinas quelantes com grupos amidoxima foram sintetizadas por copolimerização em suspensão de acrilonitrila (AN e divinilbenzeno (DVB e subsequente modificação química dos grupos ciano por reação com hidroxilamina. Na copolimerização, a proporção de divinilbenzeno e o grau de diluição foram variados. Gelatina e carbonato de cálcio foram usados como estabilizadores de suspensão e sulfato de sódio foi adicionado para reduzir a solubilidade da acrilonitrila em água, por meio do efeito salting out. Os copolímeros de AN/DVB e as resinas amidoxímicas obtidos foram caracterizados por meio de densidade aparente, área específica, volume de poros e teor de nitrogênio. As resinas amidoxímicas foram também avaliadas em relação a capacidade de complexação de íons cobre.Chelating resins with amidoxime groups were synthesized by suspension copolymerization of acrylonitrile (AN and divinylbenzene (DVB and subsequent chemical modification of cyano groups by reaction with hydroxylamine. In the copolymerization, the proportion of divinylbenzene and the dilution degree were varied. Gelatin and calcium carbonate were used as suspension stabilizers and sodium sulphate was added in order to reduce acrylonitrile solubility in water, by salting out effect. The AN/DVB copolymers and amidoxime resins obtained were characterized by apparent density, surface area, pore volume and by the content of nitrogen. The amidoxime resins were also evaluated in relation to the complexation capacity of copper ion.

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

    Science.gov (United States)

    Joyner, Jeff C; Cowan, J A

    2011-06-29

    A series of compounds that target reactive metal chelates to the HIV-1 Rev response element (RRE) mRNA have been synthesized. Dissociation constants and chemical reactivity toward HIV RRE RNA have been determined and evaluated in terms of reduction potential, coordination unsaturation, and overall charge associated with the metal-chelate-Rev complex. Ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), diethylenetriaminepentaacetic acid (DTPA), and 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) were linked to a lysine side chain of a Rev-derived peptide by either EDC/NHS or isothiocyanate coupling. The resulting chelate-Rev (EDTA-Rev, DTPA-Rev, NTA-Rev, and DOTA-Rev) conjugates were used to form coordination complexes with Fe(2+), Co(2+), Ni(2+), and Cu(2+) such that the arginine-rich Rev peptide could mediate localization of the metal chelates to the Rev peptide's high-affinity mRNA binding partner, RRE stem loop IIB. Metal complexes of the extended peptides GGH-Rev and KGHK-Rev, which also contain N-terminal peptidic chelators (ATCUN motifs), were studied for comparison. A fluorescence titration assay revealed high-affinity RRE RNA binding by all 22 metal-chelate-Rev species, with K(D) values ranging from ~0.2 to 16 nM, indicating little to no loss of RNA affinity due to the coupling of the metal chelates to the Rev peptide. Dissociation constants for binding at a previously unobserved low-affinity site are also reported. Rates of RNA modification by each metal-chelate-Rev species were determined and varied from ~0.28 to 4.9 nM/min but were optimal for Cu(2+)-NTA-Rev. Metal-chelate reduction potentials were determined and varied from -228 to +1111 mV vs NHE under similar solution conditions, allowing direct comparison of reactivity with redox thermodynamics. Optimal activity was observed when the reduction potential for the metal center was poised between those of the two principal co-reagents for metal-promoted formation of

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

    Science.gov (United States)

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

    2007-12-01

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

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

    Directory of Open Access Journals (Sweden)

    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

  1. Action of chelators on solid iron in phosphate-containing aqueous solutions

    International Nuclear Information System (INIS)

    To study the effect of strong iron-ligands on steel corrosion, mild steel electrodes were immersed in solutions containing 20 mM phosphate buffer (pH=7.2) and between 0.01 mM and 1 M of either the iron(II)-chelators 2,2'-bipyridine or FerroZine, or the iron(III)-chelators citrate or acetylacetonate. Resulting surface reactions were investigated by quantifying the electrochemical potential (E), the electrochemical polarization resistance (Rp), the corrosion current (Icorr) and the release of iron into solution. The surface was further analyzed by scanning electron microscopy (SEM/SEM-EDAX) and atomic force microscopy. Concentrations of 0.1 mM of any of the chelators led to slight, temporary changes in E, Icorr and Rp. Concentrations of 10 mM resulted in characteristic changes of E, which were the same for all chelators and in the precipitation of FePO4 in the case of citrate and acetylacetonate, or vivianite [Fe3(PO4)2 · 8H2O] in the case of bipyridine and FerroZine. Concentrations of 1 mM of both iron(III)-chelators led to a temporary drop of E similar to that found with 0.1 mM chelator. With iron(II)-chelators, E dropped to about -500 mV before oscillating for several days. The amplitudes of the oscillations were up to 200 mV with periods of 30 and 20-25 min for bipyridine and FerroZine, respectively

  2. Comparison of bifunctional chelates for {sup 64}Cu antibody imaging

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Cara L.; Crisp, Sarah; Bensimon, Corinne [MDS Nordion, Vancouver, BC (Canada); Yapp, Donald T.T.; Ng, Sylvia S.W. [British Columbia Cancer Agency Research Centre, Vancouver, BC (Canada); University of British Columba, The Faculty of Pharmaceutical Sciences, Vancouver, BC (Canada); Sutherland, Brent W. [British Columbia Cancer Agency Research Centre, Vancouver, BC (Canada); Gleave, Martin [Prostate Centre at Vancouver General Hospital, Vancouver, BC (Canada); Jurek, Paul; Kiefer, Garry E. [Macrocyclics Inc., Dallas, TX (United States)

    2010-11-15

    Improved bifunctional chelates (BFCs) are needed to facilitate efficient {sup 64}Cu radiolabeling of monoclonal antibodies (mAbs) under mild conditions and to yield stable, target-specific agents. The utility of two novel BFCs, 1-Oxa-4,7,10-triazacyclododecane-5-S-(4-isothiocyanatobenzyl)-4,7,10-triacetic acid (p-SCN-Bn-Oxo-DO3A) and 3,6,9,15-tetraazabicyclo[9.3.1]pentadeca-1(15),11,13-triene-4-S-(4-isothiocyanatobenzyl)-3,6,9-triacetic acid (p-SCN-Bn-PCTA), for mAb imaging with {sup 64}Cu were compared to the commonly used S-2-(4-isothiocyanatobenzyl)-1,4,7,10-tetraazacyclododecane-tetraacetic acid (p-SCN-Bn-DOTA). The BFCs were conjugated to trastuzumab, which targets the HER2/neu receptor. {sup 64}Cu radiolabeling of the conjugates was optimized. Receptor binding was analyzed using flow cytometry and radioassays. Finally, PET imaging and biodistribution studies were done in mice bearing either HER2/neu-positive or HER2/neu-negative tumors. {sup 64}Cu-Oxo-DO3A- and PCTA-trastuzumab were prepared at room temperature in >95% radiochemical yield (RCY) in <30 min, compared to only 88% RCY after 2 h for the preparation of {sup 64}Cu-DOTA-trastuzumab under the same conditions. Cell studies confirmed that the immunoreactivity of the mAb was retained for each of the bioconjugates. In vivo studies showed that {sup 64}Cu-Oxo-DO3A- and PCTA-trastuzumab had higher uptake than the {sup 64}Cu-DOTA-trastuzumab at 24 h in HER2/neu-positive tumors, resulting in higher tumor to background ratios and better tumor images. By 40 h all three of the {sup 64}Cu-BFC-trastuzumab conjugates allowed for clear visualization of the HER2/neu-positive tumors but not the negative control tumor. The antibody conjugates of PCTA and Oxo-DO3A were shown to have superior {sup 64}Cu radiolabeling efficiency and stability compared to the analogous DOTA conjugate. In addition, {sup 64}Cu-PCTA and Oxo-DO3A antibody conjugates may facilitate earlier imaging with greater target to background ratios than

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

    OpenAIRE

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

    2012-01-01

    This article outlines evidence that advanced glycation end product (AGE) inhibitors and breakers act primarily as chelators, inhibiting metal-catalyzed oxidation reactions that catalyze AGE formation. We then present evidence that chelation is the most likely mechanism by which ACE inhibitors, angiotensin receptor blockers, and aldose reductase inhibitors inhibit AGE formation in diabetes. Finally, we note several recent studies demonstrating therapeutic benefits of chelators for diabetic car...

  4. Overriding Felkin Control: A General Method for Highly Diastereoselective Chelation-Controlled Additions to α-Silyloxy Aldehydes

    OpenAIRE

    Stanton, Gretchen R.; Johnson, Corinne N.; Walsh, Patrick J.

    2010-01-01

    According to the Felkin-Anh and Cram-chelation models, nucleophilic additions to α-silyloxy aldehydes procees through a non-chelation pathway due to the steric and electronic properties of the silyl group, giving rise to Felkin addition products. Herein we describe a general method to promote chelation-control in additions to α-silyloxy aldehydes. Dialkylzincs, functionalized dialkylzincs, and (E)-disubstituted, (E)-trisubstituted, and (Z)-disubstituted vinylzinc reagents add to silyl-protect...

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

    International Nuclear Information System (INIS)

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

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

    OpenAIRE

    Beltrami, Diego

    2009-01-01

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

  7. Thumbnail Sketches: EDTA-Type Chelating Agents in Everyday Consumer Products: Some Medicinal and Personal Care Products.

    Science.gov (United States)

    Hart, J. Roger

    1984-01-01

    Discusses various ethylenediaminetetraacetate (EDTA)-type chelating agents found in ophthalmic products, personal care products, and disinfectants. Also discusses the properties and action of these EDTA agents. (JN)

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

    Science.gov (United States)

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

    2016-06-15

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

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

    International Nuclear Information System (INIS)

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

  10. Intracellular reduction/activation of a disulfide switch in thiosemicarbazone iron chelators

    Science.gov (United States)

    Akam, Eman A.; Chang, Tsuhen M.; Astashkin, Andrei V.

    2014-01-01

    Iron scavengers (chelators) offer therapeutic opportunities in anticancer drug design by targeting the increased demand for iron in cancer cells as compared to normal cells. Prochelation approaches are expected to avoid systemic iron depletion as chelators are liberated under specific intracellular conditions. In the strategy described herein, a disulfide linkage is employed as a redox-directed switch within the binding unit of an antiproliferative thiosemicarbazone prochelator, which is activated for iron coordination following reduction to the thiolate chelator. In glutathione redox buffer, this reduction event occurs at physiological concentrations and half-cell potentials. Consistent with concurrent reduction and activation, higher intracellular thiol concentrations increase cell susceptibility to prochelator toxicity in cultured cancer cells. The reduction of the disulfide switch and intracellular iron chelation are confirmed in cell-based assays using calcein as a fluorescent probe for paramagnetic ions. The resulting low-spin Fe(III) complex is identified in intact Jurkat cells by EPR spectroscopy measurements, which also document a decreased concentration of active ribonucleotide reductase following exposure to the prochelator. Cell viability and fluorescence-based assays show that the iron complex presents low cytotoxicity and does not participate in intracellular redox chemistry, indicating that this antiproliferative chelation strategy does not rely on the generation of reactive oxygen species. PMID:25100578

  11. Intracellular reduction/activation of a disulfide switch in thiosemicarbazone iron chelators.

    Science.gov (United States)

    Akam, Eman A; Chang, Tsuhen M; Astashkin, Andrei V; Tomat, Elisa

    2014-10-01

    Iron scavengers (chelators) offer therapeutic opportunities in anticancer drug design by targeting the increased demand for iron in cancer cells as compared to normal cells. Prochelation approaches are expected to avoid systemic iron depletion as chelators are liberated under specific intracellular conditions. In the strategy described herein, a disulfide linkage is employed as a redox-directed switch within the binding unit of an antiproliferative thiosemicarbazone prochelator, which is activated for iron coordination following reduction to the thiolate chelator. In glutathione redox buffer, this reduction event occurs at physiological concentrations and half-cell potentials. Consistent with concurrent reduction and activation, higher intracellular thiol concentrations increase cell susceptibility to prochelator toxicity in cultured cancer cells. The reduction of the disulfide switch and intracellular iron chelation are confirmed in cell-based assays using calcein as a fluorescent probe for paramagnetic ions. The resulting low-spin Fe(III) complex is identified in intact Jurkat cells by EPR spectroscopy measurements, which also document a decreased concentration of active ribonucleotide reductase following exposure to the prochelator. Cell viability and fluorescence-based assays show that the iron complex presents low cytotoxicity and does not participate in intracellular redox chemistry, indicating that this antiproliferative chelation strategy does not rely on the generation of reactive oxygen species. PMID:25100578

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

    International Nuclear Information System (INIS)

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

  13. 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. PMID:26856546

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

  16. 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.

  17. High-throughput assay comparison and standardization for metal chelating capacity screening: A proposal and application.

    Science.gov (United States)

    Santos, Jânio Sousa; Alvarenga Brizola, Vitor Rafael; Granato, Daniel

    2017-01-01

    Aiming to standardize the experimental protocols to assess the ability to chelate Fe(2+) and Cu(2+) using 96-well microplates, we analyzed Brazilian coffees (n=20) as a study-case in relation to their antioxidant activity using conventional methods (DPPH and FRAP assays) and correlated the results with the total phenolic content (TPC) using bivariate and multivariate statistical approaches. Complementarily, we assessed the repeatability, reproducibility, recovery, and linearity of both methods. Data showed that the proposed assays presented a good repeatability and reproducibility (assays, respectively. Both methods were linear in the range of 0-100mg EDTA equivalents/L. Cu(2+)-chelating ability was significantly correlated to FRAP, DPPH, and TPC, while sparse (passays can be used to assess the ability of plant-based extracts to chelate Fe(2+) and Cu(2+)in vitro. PMID:27507505

  18. Overview of guidelines on iron chelation therapy in patients with myelodysplastic syndromes and transfusional iron overload.

    Science.gov (United States)

    Gattermann, Norbert

    2008-07-01

    Between 2002 and 2008, a number of consensus statements and guidelines were developed by various groups around the world to educate healthcare professionals on the treatment of myelodysplastic syndromes (MDS), including the management of transfusional iron overload with iron chelation therapy. Guidelines have been developed by The Italian Society of Hematology, The UK MDS Guidelines Group, The Nagasaki Group, The National Comprehensive Cancer Network, and The MDS Foundation. These guidelines show that the approaches to managing iron overload in patients with MDS are region specific, differing in their recommendations for when iron chelation therapy should be initiated and strategies for the ongoing management of iron overload. The guidelines all agree that red blood cell transfusions are clinically beneficial to treat the symptomatic anemia in MDS, and that patients with low-risk MDS receiving transfusions are the most likely to benefit from iron chelation therapy. PMID:18581200

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

    Science.gov (United States)

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

    2008-10-01

    Exposure to heavy metals is a common phenomenon due to their environmental pervasiveness. Metal intoxication particularly neurotoxicity, genotoxicity, or carcinogenicity is widely known. This review summarizes our current understanding about the mechanism by which metalloids or heavy metals (particularly arsenic, lead, cadmium and mercury) induce their toxic effects. The unifying factor in determining toxicity and carcinogenicity for all these metals is the generation of reactive oxygen and nitrogen species. The toxic manifestations of these metals are caused primarily due to imbalance between pro-oxidant and antioxidant homeostasis which is termed as oxidative stress. Besides these metals have high affinity for thiol groups containing enzymes and proteins, which are responsible for normal cellular defense mechanism. Long term exposure to these metals could lead to apoptosis. Signaling components affected by metals include growth factor receptors, G-proteins, MAP kinases and transcription factors. Chelation therapy with chelating agents like calcium disodium ethylenediamine tetra acetic acid (CaNa(2)EDTA), British Anti Lewisite (BAL), sodium 2,3-dimercaptopropane 1-sulfonate (DMPS), meso 2,3-dimercaptosuccinic acid (DMSA) etc., is considered to be the best known treatment against metal poisoning. Despite many years of research we are still far away from effective treatment against toxicity caused due to exposure to heavy metals/metalloids. The treatment with these chelating agents is compromised with number of serious side-effects. Studies show that supplementation of antioxidants along-with a chelating agent prove to be a better treatment regimen than monotherapy with chelating agents. This review attempts a comprehensive account of recent developments in the research on heavy metal poisoning particularly the role of oxidative stress/free radicals in the toxic manifestation, an update about the recent strategies for the treatment with chelating agents and a

  20. Ethyl acetoacetate ligand distribution in the course of titanium n-butoxide chelation

    Energy Technology Data Exchange (ETDEWEB)

    Kurajica, S., E-mail: stankok@fkit.hr; Škorić, I.; Lozić, I.; Mandić, V.

    2014-10-15

    Sols obtained by chelation of titanium n-butoxide with ethyl acetoacetate, Eaa, in various ratios have been subjected to FTIR, {sup 1}H and {sup 13}C NMR, HSQC and UV–Vis spectroscopy in order to provide insight in the compounds obtained, their structure and quantitative relationships. Three compounds, the bis-chelated monomer, Ti(O{sup n}Bu){sub 2}(Eaa){sub 2}, bis-chelated dimer, (Ti(O{sup n}Bu){sub 3}Eaa){sub 2} and monochelated dimer, Ti{sub 2}(O{sup n}Bu){sub 7}Eaa have been established. As the molar ratio Eaa/Ti(O{sup n}Bu){sub 4} increases, the coordination changes from the monochelated and bis-chelated dimer to the bis-chelated monomer. Additionally, the transesterification reaction, influencing the chemical composition of the compounds was noted. The hydrolysis of the prepared sols was partial, leaving some residual butoxy and ethyl acetoacetate groups attached to titanium. Thermal treatment of the prepared amorphous gels at 350 °C yielded with the formation of nanocrystalline anatase. It was noted that high Eaa/Tnb ratio slightly retards the anatase formation. - Highlights: • Titanium n-butoxide was modified with ethyl acetoacetate in various ratios. • Among other chelate phases, previously undescribed Ti{sub 2}(O{sup n}Bu){sub 7}Eaa was obtained. • NMR-based mass balance procedure was introduced to obtain quantitative relationships. • The transesterification reaction has been noted. • Nanocrystalline anatase has been obtained by thermal treatment at 350 °C.

  1. Novel "hybrid" iron chelators derived from aroylhydrazones and thiosemicarbazones demonstrate selective antiproliferative activity against tumor cells.

    Science.gov (United States)

    Lovejoy, David B; Richardson, Des R

    2002-07-15

    We previously demonstrated that 2-hydroxy-1-naphthylaldehyde isonicotinoyl hydrazone (311) and other aroylhydrazone chelators possess potent antineoplastic activity because of their ability to bind iron (Fe). From these studies, we identified structural components of the hydrazones that provide antineoplastic activity, namely the salicylaldehyde and 2-hydroxy-1-naphthylaldehyde moieties. A related group of chelators known as the thiosemicarbazones also show pronounced antitumor activity because of their ability to inhibit ribonucleotide reductase. Considering this, we designed a new series of "hybrid ligands" by condensation of the aldehydes described above with a range of thiosemicarbazides. The parent compound of these ligands is 2-hydroxy-1-naphthylaldehyde thiosemicarbazone (NT). Of 8 NT analogues, 3 chelators, namely NT, N4mT (2-hydroxy-1-naphthylaldehyde-4-methyl-3-thiosemicarbazone), and N44mT (2-hydroxy-1-naphthylaldehyde-4,4-dimethyl-3-thiosemicarbazone), showed high antiproliferative activity against SK-N-MC neuroepithelioma cells (50% inhibitory concentration [IC(50)] = 0.5-1.5 microM). Indeed, their activity was significantly (P <.0001) greater than that of desferrioxamine (DFO) (IC(50) = 22 microM). We demonstrate that 311, a 311 analogue (311m), and several NT-series chelators have significantly (P <.001) greater antiproliferative activity against tumor cells than against a range of normal cell types. For example, the IC(50) values of NT and N4mT in SK-N-MC neuroepithelioma cells were 0.5 microM, whereas for fibroblasts the IC(50) values were greater than 25 microM. Further, the effect of one of the most potent chelators (311m) on preventing the growth of bone marrow stem cell cultures was far less than that of doxorubicin and similar to that of cisplatin. These studies support the further development of these chelators as antiproliferative agents. PMID:12091363

  2. 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.

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

    International Nuclear Information System (INIS)

    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 Ca2+, Cu2+ and Mn2+ 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

  4. Direct measurement of metal ion chelation in the active site of human ferrochelatase†

    OpenAIRE

    Hoggins, M.; Dailey, H. A.; Hunter, C.N.; Reid, J. D.

    2007-01-01

    The final step in heme biosynthesis, insertion of ferrous iron into protoporphyrin IX, is catalyzed by protoporphyrin IX ferrochelatase (E.C. 4.99.1.1). It is demonstrated that the pre-steady state human ferrochelatase (R115L) shows a stoichiometric burst of product formation and substrate consumption, consistent with a rate determining step following metal-ion chelation. Detailed analysis shows that chelation requires at least two steps, rapid binding followed by a slower (k ca. 1 s−1) irrev...

  5. Chelation of Schiff bases with rare earth metal ions - thermodynamic study

    International Nuclear Information System (INIS)

    Chelating tendencies of 5-chloro-orthohydroxy acetophenone-p-chloro phenyl anil and 5-chloro-orthohydroxy acetophenone-p-bromo phenyl anil towards the f-block metal ions have been investigated potentiometrically at various temperatures in 60:40 ethanol-water medium and 0.1M (NaClO4) ionic strength. Formation of 1:1 and 1:2 chelates was detected. Thermodynamic parameters for metal-ligand stability constants have been obtained by the temperature coefficie nt method. (author). 7 refs

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

    OpenAIRE

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

    1986-01-01

    We studied 29 patients with thalassaemia major who had received intensive chelation for between 6.2 and 8.8 years. All patients had normal oral glucose tolerance tests before subcutaneous chelation therapy was introduced and 22 of 29 patients had normal liver function tests. At the end of the period of study 12 patients still had normal oral glucose tolerance (7 with normal liver function tests and 5 with chronic active hepatitis). On the other hand, 11 patients had developed impaired glucose...

  7. Studies of inclusion complexes between cyclodextrins and polyazamacrocyclic chelates of lanthanide (III) ions

    OpenAIRE

    Henriques, Elsa S.; Bastos, Margarida; Geraldes, Carlos F. G. C.; Ramos, Maria João

    2003-01-01

    The complexes between [gamma]-cyclodextrin and lanthanide (III) chelates of the polyazamacrocycles DOTA (DOTA [reverse not equivalent] 1,4,7,10-tertraazacyclododecane-1,4,7,10-tetraacetate) and DOTP (DOTP [reverse not equivalent] 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetramethylenephosphonate) have been thought out to enhance the potential of such chelates as contrast agents for MRI. Given the actual demand for the design of new contrast agents, we thought it worthwhile to confirm previous ...

  8. Synthesis, characterization and biological studies of 1,7- dinaphthyl heptanoids and their metal chelates

    OpenAIRE

    S. Sindhu; Seena Thomachan; V D John

    2015-01-01

    The present investigation includes the synthesis, characterization, antitumour and antimicrobial activities of three new curcuminoid analogues and their metal chelates. Curcuminoid analogues and their metal chelates have great ability to act as antitumour and antimicrobial agents which motivated us and lead to this present work. The new curcuminoid analogues namely 1,7-di(1-naphthyl)-1,6-heptadiene-3,5-dione (1a), 1,7-di(2-methoxy 1-naphthyl)-1,6-heptadiene-3,5-dione (1b), 1,7-di(2-hydroxy ...

  9. Analysis of hydrosoluble organic chelating agents. Potentialities of capillary electrophoresis and ionic chromatography

    International Nuclear Information System (INIS)

    Capillary electrophoresis and ion exchange chromatography are good techniques for the determination of organic chelating agents as mono or poly-carboxylates. Ion exchange chromatography allows to obtain very high sensitivities (a few μg/L). Capillary electrophoresis generates practically none analytical waste; this technique is then very interesting for nuclear industry. This microanalysis technique has been here carried out for the determination of organic chelating agents in leaching water of an old waste for which an important release rate of radio-toxic metals had been found. Thus, formate and especially acetate ions have been correlated with this unusual behaviour

  10. DCCP and DICP: Construction and Analyses of Databases for Copper- and Iron-Chelating Proteins

    Institute of Scientific and Technical Information of China (English)

    Hao Wu; Yan Yang; Sheng-Juan Jiang; Ling-Ling Chen; Hai-Xia Gao; Qing-Shan Fu; Feng Li; Bin-Guang Ma; Hong-Yu Zhang

    2005-01-01

    Copper and iron play important roles in a variety of biological processes, especially when being chelated with proteins. The proteins involved in the metal binding,transporting and metabolism have aroused much interest. To facilitate the study on this topic, we constructed two databases (DCCP and DICP) containing the known copper- and iron-chelating proteins, which are freely available from the website http:∥sdbi.sdut.edu.cn/en. Users can conveniently search and browse all of the entries in the databases. Based on the two databases, bioinformatic analyses were performed, which provided some novel insights into metalloproteins.

  11. Complexes of quinone-functionalized chelating ligands for multiple electron/proton transfer reduction reactions

    Energy Technology Data Exchange (ETDEWEB)

    Durfee, W.S.; Pierpont, C.G. (Univ. of Colorado, Boulder (United States))

    1993-03-03

    Quinone-functionalized chelating ligands may be used to effect sequential electron/proton transfer steps necessary for the reduction of substrate molecules coordinated to a complexed metal ion. The chelating ligand (NQ)[sub 2]en has been synthesized by condensing 2 equiv of 2-hydroxy-3-acetyl-1,4-naphthoquinone with ethylenediamine. Complexes of Cu(II) and Ni(II) have been prepared and characterized. Electrochemical properties of the complexes show that, in the fully reduced bis(hydroquinone) form, the ligand would be able to provide four electrons and protons to a coordinated substrate molecule at strongly negative potentials. 8 refs., 2 figs.

  12. Removal of cobalt- and mercury-EDTA chelates from aqueous solutions with a macroporous char

    International Nuclear Information System (INIS)

    A bench-scale method was developed to remove cobalt- and mercury-EDTA chelates from water onto macroporous char. Experimental parameters included variations on solution pH, char pre-treatment, cobalt oxidation state, and apparatus configuration. The use of 60Co and 203Hg radiotracers allowed for total accountability of the metals in the char and effluents. Overall experimental results demonstrate the applicability of treated macroporous chars for the effective removal of both cobalt and mercury EDTA chelates from aqueous solutions. The char system was optimized to sequester 97.5% and 99.8% of the cobalt- and mercury-EDTA from 20 ppm solutions, respectively. (author)

  13. The synthesis of macroreticular chelating resins containing amidoxime groups and their properties of recovery of uranium

    International Nuclear Information System (INIS)

    Macroreticular chelating resins containing amidoxime groups were successfully synthesized with divinyl benzene (DVB) cross-linking acrylonitrile (AN) copolymer beads as skeleton by suspension polymerization. Influence factors of DVB-AN beads' amidoxime reaction, such as reaction medium, reaction ratio, reaction temperature and time etc. were studied in detail. Copolymer and chelating resins with amidoxime groups having different physical properties and monomer composition were prepared successfully. The factors affecting resin chemical adsorption capacity, such as cross-linking agent, reticulating agent and polar monomer etc. were also explored. The resins had chemical adsorption capacity over 4.0 mmol/g (dry), and ideal results of recovered uranium under the conditions as described

  14. Synthesis and Analytical Study of New Chelating Resin Containing Sulfadiazine Drug

    OpenAIRE

    Madher N. Abdulla

    2010-01-01

    A new chelating resin was prepared by mixing sulfadiazine drug and TMP (trimethylolphenol). It was polymerized by heating to 90 °C then it was post cured to 100 °C after that it was grinded. The chelating behavior was examined against Cu2+, Ni2+ using patch method in deferent conditions like treatment time and pH at room temperature. The resin show a good loading capacity toward Cu2+ (in treatment time = 3 h & pH=4) = 0.2174 mg ion / 100 mg resin and it show good loading capacity toward Ni2+ ...

  15. Chelation behavior of various flavonols and transfer of flavonol-chelated zinc(II) to alanylaspartic dipeptide: A PCM/DFT investigation

    Science.gov (United States)

    Yasarawan, Nuttawisit; Thipyapong, Khajadpai; Ruangpornvisuti, Vithaya

    2016-03-01

    Alanylaspartic dipeptide (AlaAsp) and zinc(II)-flavonol complex could represent a metal-binding site in proteins and a metal-ion releasing agent, respectively. Chelation of zinc(II) by either AlaAsp or flavonol ligands in aqueous solution has been examined using DFT methods with polarizable continuum model (PCM/DFT). Coordination geometry, complexation stoichiometry, coordination bond strength, preferable metal-binding site on ligands and effect of water coordination on the stability of complexes have been addressed. In several cases, the long-range corrected density functional CAM-B3LYP allows the most accurate prediction of both structural and spectroscopic data. The preferential transfer of flavonol-chelated zinc(II) to AlaAsp under solvation is attainable through the ligand-exchange reaction. The energy barrier of such reaction is significantly dependent on the degree of hydrogen bonding within the transition state. In summary, either hydroxylation or methoxylation at particular positions on the 3-hydroxyflavone backbone significantly affects the reactivity of flavonol chelates in the metal-ion transfer.

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

    International Nuclear Information System (INIS)

    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

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

    Science.gov (United States)

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

    2015-03-15

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

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

    DEFF Research Database (Denmark)

    Liu, Yang; Yang, Liang; Molin, Søren

    2010-01-01

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

  19. 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.

  20. 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; Nick, Hanspeter; Wood, John C

    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 ...

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

    International Nuclear Information System (INIS)

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

  2. 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.

  3. Spectral, magnetic and antifungal activities of some novel lanthanon chelates of Schiff bases containing oxygen and nitrogen donor atoms

    International Nuclear Information System (INIS)

    Lanthanon chelates of the type (LnL2) and (LnL3) where Ln = La(III), Pr(III), Nd(III), Sm(III), Ho(III) and Er(III) and L = acetylacetonethiosemicarbazide (AAS) and L' = benzoylacetonethiosemicarbazide (BAS) have been isolated in solid state and are characterized by their spectral, magnetic and antifungal activities. The electronic spectra of these chelates have been analyzed in the light of LSJ terms and involving characteristic f - f transitions. The ligands and their resulting chelates have been shown to be toxic against the two pathogenic fungi, viz., Aspargillus niger and Draschelara australiensis and the results revealed that the toxicity decreases on chelation or metallation. Overall, the benzoylacetonesemicarbazide lanthanon chelates are more toxic to fungi than the corresponding lanthanon derivatives of acetylacetonesemicarbazide. (author)

  4. A Comparison of Methods Used to Evaluate Intakes of Transuranics Influenced by Chelation Therapy

    International Nuclear Information System (INIS)

    A comparison of methods is used to evaluate the intake of transuranics influenced by chelation therapy. The purpose of this paper is to introduce the mechanistic method by using it to validate Hall's method and Jech's method. This is accomplished by using the mechanistic method to generate a known set of data suitable for benchmarking all three methods

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

    International Nuclear Information System (INIS)

    The overall objectives of this project were to gain a fundamental understanding of the solubility and phase behavior of metal chelates in supercritical CO2. Extraction with CO2 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 CO2 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 CO2 and CO2/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 CO2 and CO2/co-contaminant mixtures. Thus, they can now design and optimize processes to extract metals from solid matrices using supercritical CO2, as an alternative to hazardous organic solvents that create their own environmental problems, even while helping in metals decontamination

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

    International Nuclear Information System (INIS)

    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)

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

    Science.gov (United States)

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

    2013-04-01

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

  8. Growth and Decay: An Experiment Demonstrating Radioactivity Relationships and Chelate Solvent Extraction Separations.

    Science.gov (United States)

    Downey, D. M.; And Others

    1984-01-01

    The separation of lead and bismuth by chelate solvent extraction is of interest because of the simplicity which the use of radiotracers allows in its demonstration. Theoretical background information, procedures, materials needed, and typical results are provided for an experiment involving the extraction. (JN)

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

    Institute of Scientific and Technical Information of China (English)

    Guo Chen YANG; Hai Jian YANG

    2006-01-01

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

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

    Institute of Scientific and Technical Information of China (English)

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

    2005-01-01

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

  11. Modern Chemistry Techniques Applied to Metal Behavior and Chelation in Medical and Environmental Systems ? Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Sutton, M; Andresen, B; Burastero, S R; Chiarappa-Zucca, M L; Chinn, S C; Coronado, P R; Gash, A E; Perkins, J; Sawvel, A M; Szechenyi, S C

    2005-02-03

    This report details the research and findings generated over the course of a 3-year research project funded by Lawrence Livermore National Laboratory (LLNL) Laboratory Directed Research and Development (LDRD). Originally tasked with studying beryllium chemistry and chelation for the treatment of Chronic Beryllium Disease and environmental remediation of beryllium-contaminated environments, this work has yielded results in beryllium and uranium solubility and speciation associated with toxicology; specific and effective chelation agents for beryllium, capable of lowering beryllium tissue burden and increasing urinary excretion in mice, and dissolution of beryllium contamination at LLNL Site 300; {sup 9}Be NMR studies previously unstudied at LLNL; secondary ionization mass spec (SIMS) imaging of beryllium in spleen and lung tissue; beryllium interactions with aerogel/GAC material for environmental cleanup. The results show that chelator development using modern chemical techniques such as chemical thermodynamic modeling, was successful in identifying and utilizing tried and tested beryllium chelators for use in medical and environmental scenarios. Additionally, a study of uranium speciation in simulated biological fluids identified uranium species present in urine, gastric juice, pancreatic fluid, airway surface fluid, simulated lung fluid, bile, saliva, plasma, interstitial fluid and intracellular fluid.

  12. Spectroscopy, modeling and computation of metal chelate solubility in supercritical CO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    J. F. Brennecke; M. A. Stadtherr

    1999-12-10

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

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

    International Nuclear Information System (INIS)

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

  14. Quenching of the triplet state of benzophenone by lanthanide 1,3-diketonate chelates in solutions

    International Nuclear Information System (INIS)

    The phosphorescence of benzophenone in benzene and acetonitrile was quenched by several lanthanide (Sm, Eu, Gd, Tb and Dy) acetylacetonate chelates. The results of Stern-Volmer analysis including the quenching of benzophenone triplet and sensitization of lanthanide emission indicate that the quenching process occurs by the energy transfer mechanism via the excited triplet state of the ligand. (Author)

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

    Science.gov (United States)

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

  16. Flavonoids function as antioxidants: By scavenging reactive oxygen species or by chelating iron?

    Science.gov (United States)

    Wuguo, Deng; Xingwang, Fang; Jilan, Wu

    1997-09-01

    Flavonoids have been reported to exhibit strong antioxidative activity. In the present work, a systematic mechanistic study has been performed on five flavonoids (baicalin, hesperidin, naringin, quercetin and rutin) selected according to their structural characteristics. The experimental results reveal that flavonoids function as antioxidant mainly by chelating iron ions and by scavenging peroxyl radicals whereas their OH radical scavenging effect is much less important.

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

    International Nuclear Information System (INIS)

    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.)

  18. Use of organometallic chelates in broiler diet: effect on the performance and bone structure. Preliminary results

    Directory of Open Access Journals (Sweden)

    Biagina Chiofalo

    2010-01-01

    Full Text Available On 26,000 Ross 508 broiler chickens (two groups of 13,000 per pen the effect of dietary substitution with in organic trace minerals or organometallic chelates on performances and bones tructure c trace minerals or organometallic chelates on performances and bone structure was studied. Treatments consisted of a commercial diet integrated with 0.5% of a vitamin-mineral premix containing inorganic trace minerals (CTR or organometallic chelates (MHA using Methionine Hydroxy Analog. Production performance was measured during the 52 d trial period and bone structure was evalu- ated at the slaughter (52 d. Significant (P=0.038 higher values were observed in the finishing period (41 to 52 d for the body weight of the treated group (3560 g vs. 3358 g. The same trend was observed for the ADG (MHA 87.6 g/d vs. CTR 71 g/d; P<0.05. Concerning ash percentage significant higher values were observed in the CTR group for femur (49.01% vs. 51.45%; P<0.01 and tibia (53.87% vs. 49.79%; P<0.001; femur showed also higher values for bone radiopacity (MHA 0.21 px vs. CTR 0.26 px; P=0.035. MHA group showed significant higher value for morphometric measures of the femur and tibia. Results suggest that organometallic chelates can be included in the diet without compromising broiler performance.

  19. Kinetic Studies on Forming Iso-nuclear -type Chelates of Rare Earths with p-Sulphoaminobromophosphonazo

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The kinetic behavior of forming the iso-nuclear b -type chelates of rare earth ions (RE3+) with p-sulphoaminobromophosphonazo (BPA-pSN) in ClCH2COOH-CH3COONa buffer solutions were studied by a spectrophotometric method.

  20. Synergic effect of chelating agent and oxidant on chemical mechanical planarization

    International Nuclear Information System (INIS)

    Chemically dominant alkaline slurry, which is free of BTA (benzotriazole) and other inhibitors, was investigated. The synergic effect of the chelating agent and oxidant on the chemical mechanical planarization (CMP) was taken into consideration. Copper CMP slurry is mainly composed of an oxidizer, nonionic surfactant, chelating agent and abrasive particles. The effect of different synergic ratios of oxidant with chelating agent on the polishing removal rate, static etch rate and planarization were detected. The planarization results reveal that with the increase of oxidant concentration, the dishing value firstly diminished and then increased again. When the synergic ratios is 3, the dishing increases the least. A theoretical model combined with chemical-mechanical kinetics process was proposed in the investigation, which can explain this phenomenon. Based on the theoretical model, the effect of synergic ratios of oxidant with chelating agent on velocity D-value (convex removal rate minus recessed removal rate) was analyzed. The results illustrate that when the synergic ratio is between 2.5–3.5, the velocity D-value is relatively higher, thereby good planarization can be achieved in this interval. This investigation provides a new guide to analyze and study copper line corrosion in the recessed region during copper clearing polishing. (semiconductor technology)

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Paine, R.T.

    2000-12-12

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

  3. FTIR, magnetic, mass spectral, XRD and thermal studies of metal chelates of tenoxicam

    Science.gov (United States)

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

    2007-09-01

    Metal chelates of anti-inflammatory drug, tenoxicam (Ten), are synthesized and characterized using elemental analyses, IR, solid reflectance, magnetic, mass spectra, thermal analyses (TGA and DTA) and X-ray powder diffraction techniques. The chelates are found to have the general formulae [M(H 2L) 2(H 2O) x] (A) 2· yH 2O (where H 2L = neutral Ten, A = Cl in case of Ni(II) and Co(II) or AcO in case of Cu(II) and Zn(II) ions, x = 0-2 and y = 0-2.5) and [M(H 2L) 3](A) z· yH 2O (A = SO 4 in case of Fe(II) ion ( z = 1) or Cl in case of Fe(III) ( z = 3) and y = 0-4). IR spectra reveal that Ten behaves as a neutral bidentate ligand coordinated to the metal ions through the pyridyl- N and carbonyl- O of the amide moiety. The solid reflectance spectra and magnetic moment measurements reveal that these chelates have tetrahedral, square planar and octahedral geometrical structures. Mass spectra are also used to confirm the proposed formulae and the possible fragments resulted from fragmentation of Ten and its Zn(II) and Cu(II) chelates are suggested. The thermal behaviour of the chelates (TG/DTG, DTA) are discussed in detailed manner and revealed that water molecules of crystallization together with anions are removed in the first and second steps while the Ten molecules are removed in the subsequent steps. Different thermodynamic parameters are evaluated and the relative thermal stabilities of the complexes are discussed. X-ray powder diffraction patterns are used to indicate the polymorphic form of Ten and if the complexes have molecular similarity with respect to type of coordination.

  4. Compositional analysis of metal chelating materials using near-field photothermal Fourier transform infrared microspectroscopy.

    Science.gov (United States)

    Moffat, Jonathan G; Mayes, Andrew G; Belton, Peter S; Craig, Duncan Q M; Reading, Mike

    2010-01-01

    Photothermal-Fourier transform-infrared (PT-FT-IR) microspectroscopy employs a thermal probe mounted in a scanning probe microscope (SPM). By placement of the tip of the probe on the surface of a solid sample, it can obtain localized IR spectra of a wide range of samples. A second mode of analysis is also available; a sample can be taken from the selected location using a technique called thermally assisted nanosampling (TAN), then a spectrum can be obtained of the nanosample while the probe is remote from the surface. We report a novel method of local compositional analysis that combines both of these types of measurement; a reagent is attached to the tip using TAN, then the reagent is placed in contact with analyte. IR spectroscopy can then be used to analyze any interaction between the reagent and surface it is placed in contact with. All of these modes of analysis were illustrated using a metal chelating agent. In the surface mode, changes to a solid bead of a chelating resin were measured using standard PT-FT-IR. In the nanosampling mode of analysis, a particle of a chelating polymer was attached to the tip of the probe using TAN and this was placed in contact with a concentrated calcium solution. Strong spectral changes were observed that mirrored those found when exposing the surface bound chelating resin bead to a solution of the same ion. A semiquantitative simulation of the PT spectrum for a chelating resin bead was achieved using a thermal diffusion model derived from photoacoustic spectroscopy indicating that semiquantitative or quantitative measurements will be possible in such a system. PMID:19957959

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

    Science.gov (United States)

    Aguirre, Pabla; Mena, Natalia P.; Carrasco, Carlos M.; Muñoz, Yorka; Pérez-Henríquez, Patricio; Morales, Rodrigo A.; Cassels, Bruce K.; Méndez-Gálvez, Carolina; García-Beltrán, Olimpo; González-Billault, Christian; Núñez, Marco T.

    2015-01-01

    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. PMID:26658949

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

    Science.gov (United States)

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

    2016-03-01

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

  7. 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

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

  8. Análise da pressão intra-ocular após ceratectomia fotorrefrativa com excimer laser Intraocular pressure analysis after excimer laser photorefractive keratectomy

    Directory of Open Access Journals (Sweden)

    Christiane Rolim de Moura

    2000-04-01

    Full Text Available Objetivo: Comparar os valores pré-operatórios da pressão intra-ocular (Po com os valores pós-operatórios em pacientes submetidos à ceratectomia fotorrefrativa com excimer laser, bem como, avaliar os efeitos do uso de corticosteróide tópico na Po nesse grupo.Pacientes e métodos: Foram analisados retrospectivamente 122 pacientes submetidos à ceratectomia fotorrefrativa com excimer laser para correção de miopia, no período de fevereiro de 1994 a dezembro de 1996. Esse grupo teve sua Po tomada com o tonômetro de aplanação de Goldmann no pré-operatório, 30º e 60º dias e sexto mês pós-operatório. Receberam cuidados pós-operatórios padronizados, incluindo o uso de corticosteróide tópico.Resultados: Foi observado um aumento estatisticamente significante em relação aos valores pré-operatórios nas médias da Po no 30º dia pós-operatório, ao passo que no pós-operatório de seis meses obteve-se diminuição estatisticamente significante nos valores médios da Po em relação ao pré-operatório.Conclusão:Nas fases iniciais do período pré-operatório, observou-se um aumento da Po possivelmente relacionado ao uso de corticosteróides. Após 6 meses, os valores da Po foram estatisticamente menores que os pré-operatórios.Purpose: To compare the preoperative and postoperative values of IOP in a group of patients after photorefractive keratectomy (PRK and to evaluate the sensitivy to steroid drops. Methods:One hundred and twenty-two patients who un-derwent PRK from February 1994 to December 1996 were analized retrospectively. IOP measurements were taken with a Goldmann applanation tonometer preoperatively and postoperatively on the 30th, 60th and 180th day. All of them received the same postoperative routine, including steroid drops.Results: Comparing with the preoperative values, there was a statistically significant increase in IOP on the 30th postoperative day, while there was a statistically significant decrease in IOP

  9. Photorefractive keratectomy for moderate myopia with the VISX and Summit excimer lasers: a retrospective study Ceratectomia fotorrefrativa para correção de miopia moderada com excimer lasers VISX e Summit: estudo retrospectivo

    Directory of Open Access Journals (Sweden)

    João C. Ribeiro

    2000-06-01

    Full Text Available Purpose: To present photorefractive keratectomy (PRK results for myopia ranging from -4,00 to - 6,00 diopters performed with the VISX and Summit excimer lasers. Methods: To be eligible for this study, patients had to be 20 to 45 years of age, have -4.00 to -6.00 diopters of myopia and have no more than 1 D of astigmatism. The Summit group was composed of 51 eyes. The baseline preoperative spherical equivalent of myopia was -5.22 ± 0.17 and surgeries were performed with the Excimed UV 200 LA Excimer Laser. In the VISX group, there were 53 eyes and the baseline refractive error was -4.85 ± 0.16 and surgeries were performed with the Twenty/Twenty Excimer Laser. Results: At six-month examination, haze ranged from 0 to 1 (M:0.56 ± 0.07 in the VISX group and from 0 to 3 (M:0.58 ± 0.08 in the Summit group. Uncorrected vision at six months was 20/20 or better in 22% of eyes and 20/40 or better in 83% of eyes in the VISX group. In the Summit group, 25% of eyes were 20/20 or better and 71% were 20/40 or better at the six-month examination. Conclusion: It is reassuring that PRK of patients with -4.00 to -6.00 D of myopia results in acceptable results.Objetivo: Apresentar os resultados obtidos com ceratecto-mia fotorrefrativa (PRK para a correção de miopia variando de -4,0 a -6,0 dioptrias realizadas com os excimer lasers VISX e Summit. Métodos: Para o estudo foram avaliados os resultados de PRK realizadas em pacientes com idade entre 20 e 45 anos, miopia entre -4,0 e -6,0 dioptrias e astigmatismo até 1,0 dioptria. O grupo operado com o laser da marca Summit era composto de 51 olhos. O equivalente esférico médio pré-operatório era de -5,22 ± 0,17 dioptrias e as cirurgias foram realizadas com o Excimed UV 200 LA Excimer Laser. O grupo operado com o laser VISX, era composto de 53 olhos e o erro refrativo preoperatório era de -4,85 ± 0,16 diop-trias e as cirurgias foram realizadas com o Twenty/Twenty Excimer Laser. Resultados: Exame seis meses

  10. Synthesis, Characterization, and Application of Metal-Chelating Polymers for Mass Cytometric Bioassays

    Science.gov (United States)

    Majonis, Daniel

    This thesis describes the synthesis, characterization, and application of metal-chelating polymers for mass-cytometric bioassays. Mass cytometry is a cell characterization technique in which cells are injected individually into an ICP-MS detector. Signal is provided by staining cell-surface or intracellular antigens with metal-labeled antibodies (Abs). These Abs are labeled through the covalent attachment of metal-chelating polymers which carry multiple copies of a lanthanide isotope. In this work, my first goal was to develop a facile, straightforward synthesis of a new generation of metal-chelating polymers. The synthesis began with reversible addition-fragmentation chain transfer polymerization, and was followed by numerous post-polymerization pendant group transformations to introduce DTPA lanthanide chelators to every repeat unit, and a maleimide at the end of the chain. The second goal was to apply these metal-chelating polymers in bioassay experiments. The DTPA groups were loaded with lanthanide ions, and the maleimide group was used to covalently attach the polymer to an Ab. This goat anti-mouse conjugate was found to carry an average of 2.4 +/- 0.3 polymer chains. Then, primary Ab conjugates were prepared and used in an 11-plex mass cytometry assay in the characterization of umbilical cord blood cells. The third goal was to expand the multiplexity of the assay. In current technology, the number of Abs that can be monitored simultaneously is limited to the 31 commercially available, stable lanthanide isotopes. Thus, I had an interest in preparing metal-chelating polymers that could carry other metals in the 100-220 amu range. I synthesized polymers with four different polyaminocarboxylate ligands, and investigated the loading of palladium and platinum ions into these polymers. Polymer-Ab conjugates prepared with palladium- and platinum-loaded polymers gave curious results, in that only dead cells were recognized. The fourth goal was to create dual

  11. Targeted cellular ionic calcium chelation by oxalates: Implications for the treatment of tumor cells

    Directory of Open Access Journals (Sweden)

    Embi Abraham

    2012-12-01

    Full Text Available Abstract Background In malignant melanoma, it has been published that up to 40% of cancer patients will suffer from brain metastasis. The prognosis for these patients is poor, with a life expectancy of 4 to 6 months. Calcium exchange is involved in numerous cell functions. Recently, three types of cellular calcium sequestration have been reported in the medical literature. The first describes a transgenic mouse model in which an increase of aberrant calcium channels triggers hypertrophy and apoptosis. The second provides a protective mechanism whereby astrocytes in the brain inhibit apoptosis of tumor cells by moving ionic calcium out of the tumor cells thru gap junctions. The third is via calcium chelation, which causes cell apoptosis by converting ionic calcium into a calcium salt. This process has been shown to operate in atrial myocardial cells, thus not allowing the intracellular calcium stores to flow through the myocytes intercalated discs. Ideally chemotherapeutic agents would be those that initiate apoptosis in tumor cells. Presentation of the Hypothesis We hypothesize that the recent reported intracellular calcium sequestration by oxalate chelation, due to its chemical process of converting ionic calcium into a calcium salt, may inhibit the protective effect of astrocytes on brain tumor metastasized melanoma cells by not allowing free calcium to leave the metastatic cells, simultaneously apoptosis of tumor and some healthy adjacent cells could occur. This hypothesis could be extended to include other cancerous tumors such as skin cancers amongst others. Testing the hypothesis Using the experimental model showing the protective mechanism of co-cultured reactive astrocytes and tumor cells treated with oxalates could be used to test this hypothesis in vitro. The calcium specific von Kossa technique could be used to confirm the presence of chelated intracellular calcium architecture of the metastatic cells (which is a sign of apoptosis

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

    Directory of Open Access Journals (Sweden)

    Singh Rakesh K

    2010-02-01

    Full Text Available Abstract Background Metal chelators have gained much attention as potential anti-cancer agents. However, the effects of chelators are often linked solely to their capacity to bind iron while the potential complexation of other trace metals has not been fully investigated. In present study, we evaluated the effects of various lipophilic aroylhydrazone chelators (AHC, including novel compound HNTMB, on various ovarian cancer cell lines (SKOV-3, OVCAR-3, NUTU-19. Methods Cell viability was analyzed via MTS cytotoxicity assays and NCI60 cancer cell growth screens. Apoptotic events were monitored via Western Blot analysis, fluorescence microscopy and TUNEL assay. FACS analysis was carried out to study Cell Cycle regulation and detection of intracellular Reactive Oxygen Species (ROS Results HNTMB displayed high cytotoxicity (IC50 200-400 nM compared to previously developed AHC (oVtBBH, HNtBBH, StBBH/206, HNTh2H/315, HNI/311; IC50 0.8-6 μM or cancer drug Deferoxamine, a hexadentate iron-chelator (IC50 12-25 μM. In a NCI60 cancer cell line screen HNTMB exhibited growth inhibitory effects with remarkable differences in specificity depending on the cell line studied (GI50 10 nM-2.4 μM. In SKOV-3 ovarian cancer cells HNTMB treatment led to chromatin fragmentation and activation of the extrinsic and intrinsic pathways of apoptosis with specific down-regulation of Bcl-2. HNTMB caused delayed cell cycle progression of SKOV-3 through G2/M phase arrest. HNTMB can chelate iron and copper of different oxidation states. Complexation with copper lead to high cytotoxicity via generation of reactive oxygen species (ROS while treatment with iron complexes of the drug caused neither cytotoxicity nor increased ROS levels. Conclusions The present report suggests that both, non-complexed HNTMB as a chelator of intracellular trace-metals as well as a cytotoxic HNTMB/copper complex may be developed as potential therapeutic drugs in the treatment of ovarian and other

  13. DESORPTION OF METAL IONS FROM KRAFT PULPS. PART 1. CHELATION OF HARDWOOD AND SOFTWOOD KRAFT PULP WITH EDTA

    OpenAIRE

    Kim Granholm; Leo Harju; Ari Ivaska

    2010-01-01

    Chelation of unbleached and oxygen bleached hardwood and softwood kraft pulps with EDTA was studied. The main focus was on the desorption of magnesium, manganese, and iron due to their impact in TCF-bleaching. Desorption of other metal ions present were also studied in order to get an over-all estimation of the metal ion concentrations and their desorption during chelation. By using the concept of side reaction coefficients, an estimation of the chelating strength of EDTA at different pH can ...

  14. Synthesis and characterization of some new lanthanide(III) chelates with 1,4-bis-(2'-hydroxyphenylazomethine) phenylene

    International Nuclear Information System (INIS)

    The chelates formed between 1,4-bis(2'-hydroxyphenylazomethine) phenylene with La, Ce, Pr, Nd, Sm, Gd, Dy, Er, Yb, and Lu ions have been investigated in solution using conductometric, potentiometric, and spectrophotometric methods. The studies revealed the formation of M2L and ML complexes. The solid chelates have been characterized by elemental and thermal analysis, molar conductance, IR, 1H NMR (for La and Lu chelates), and electronic spectra. The bonding takes place through the coordination of nitrogen in the -CH=N- group and the oxygen of the hydroxyl group by proton displacement. (author)

  15. Immunoreactivity and Radioimmunoscintigraphy of 4-Lysine Single Chain (Fv) Lym-1 Antibody for the Radiometal Chelation

    International Nuclear Information System (INIS)

    Small size of recombinant scFv, composed of VH and VL region of IgG, has many advantages such as faster blood clearance, improved tumor localization and reduced human anti-mouse antibody (HAMA) response. On the other hand, owing to small size, number of amino group, which was not involved in binding site, of ScFv lym-1 was insufficient in conjugation with CITC-DTPA chelator for radio metal labeling. The goal of this study is to introduce 4-lysine tag to the end of ScFv lym-1 sequence for radio metal conjugation and to evaluate the immunoreactivity and radioimmunoscintigraphy of chelator conjugated 4-lysine taq scFv lym-1 (4-lys scFv)

  16. Biological activity of ellagitannins: Effects as anti-oxidants, pro-oxidants and metal chelators.

    Science.gov (United States)

    Moilanen, Johanna; Karonen, Maarit; Tähtinen, Petri; Jacquet, Rémi; Quideau, Stéphane; Salminen, Juha-Pekka

    2016-05-01

    Ellagitannins are a subclass of hydrolysable tannins that have been suggested to function as defensive compounds of plants against herbivores. However, it is known that the conditions in the digestive tracts of different herbivores are variable, so it seems reasonable to anticipate that the reactivities and modes of actions of these ingested defensive compounds would also be different. A previous study on a few ellagitannins has shown that these polyphenolic compounds are highly oxidizable at high pH and that their bioactivity can be attributed to certain structural features. Herein, the activities of 13 ellagitannins using the deoxyribose assay were measured. The results provided information about the anti-oxidant, pro-oxidant and metal chelating properties of ellagitannins. Surprisingly, many of the tested ellagitannins exhibited pro-oxidant activities even at neutral pH and only moderate to low radical scavenging activities, although the metal chelating capacities of all tested ellagitannins were relatively high. PMID:26899362

  17. Studies on the Chelation Behaviour of Phenanthrenequinone Monosemicarbazone with Rare Earth Elements

    International Nuclear Information System (INIS)

    Interaction between phenanthrenequinone monosemicarbazone (PQS) and trivalent rare earth La, Pr, Nd, Sm, Tb, Dy and Ho has been investigated potentiometrically. The stability constants of the PQS chelates have been evaluated at temperatures 300C, 400C and 500C at constant ionic strength. The effect of variation of ionic strength was studied by taking four ionic strengths at 250C. The stability constants have been calculated on IBM 360 Fortran-IV computer using weighted least squares method. Thermodynamic parameters such as enthalpy, entropy and Gibbs energy changes characterizing the formation of normal chelates have been evaluated at 300C. The order of stabilities of rare earths with phenanthrenequinone monosemicarbazone was found to be Ho>Dy>Tb>Sm>Nd>Pr>La

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

    Science.gov (United States)

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

    2016-07-01

    A study about the suitability of the chelation reaction of Ca(2+)with ethylenediaminetetraacetic acid (EDTA) as a validation standard for Isothermal Titration Calorimeter measurements has been performed exploring the common experimental variables (buffer, pH, ionic strength and temperature). Results obtained in a variety of experimental conditions have been amended according to the side reactions involved in the main process and to the experimental ionic strength and, finally, validated by contrast with the potentiometric reference values. It is demonstrated that the chelation reaction performed in acetate buffer 0.1M and 25°C shows accurate and precise results and it is robust enough to be adopted as a standard calibration process. PMID:27154686

  19. Chelate complexes of iodine (5) fluorides with glycerin and its analogs

    International Nuclear Information System (INIS)

    Interaction of IF5 with glycerin, α-thioglycerin and guaiacol-glycerin ether in solution of acetonitrite is studied using the NMR 19F method. It is shown that as a result of the reaction chelate isomers IF3(OCH2CHOCH2OH), IF3(OCH2CHOCH2SH) and IF3(OCH2CHOCH2OC6H5OMe) are formed, in which the ligands are bonded with iodine atom through oxygen atoms of neighbouring hydroxyl groups. In the reaction of IF5 with glycerin formation of the bicyclic chelate complex IF2(OCH2CHOCH2O) is also detected, in which all oxygen atoms are bonded with iodine atom

  20. Tin-117m-labeled stannic (Sn.sup.4+) chelates

    Science.gov (United States)

    Srivastava, Suresh C.; Meinken, George E.; Richards, Powell

    1985-01-01

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

  1. Solution-processed Al-chelated gelatin for highly transparent non-volatile memory applications

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Yu-Chi; Wang, Yeong-Her, E-mail: yhw@ee.ncku.edu.tw [Institute of Microelectronics and Department of Electrical Engineering, Advanced Optoelectronic Technology Center, National Cheng-Kung University, Tainan 701 Taiwan (China)

    2015-03-23

    Using the biomaterial of Al-chelated gelatin (ACG) prepared by sol-gel method in the ITO/ACG/ITO structure, a highly transparent resistive random access memory (RRAM) was obtained. The transmittance of the fabricated device is approximately 83% at 550 nm while that of Al/gelatin/ITO is opaque. As to the ITO/gelatin/ITO RRAM, no resistive switching behavior can be seen. The ITO/ACG/ITO RRAM shows high ON/OFF current ratio (>10{sup 5}), low operation voltage, good uniformity, and retention characteristics at room temperature and 85 °C. The mechanism of the ACG-based memory devices is presented. The enhancement of these electrical properties can be attributed to the chelate effect of Al ions with gelatin. Results show that transparent ACG-based memory devices possess the potential for next-generation resistive memories and bio-electronic applications.

  2. Solution-processed Al-chelated gelatin for highly transparent non-volatile memory applications

    International Nuclear Information System (INIS)

    Using the biomaterial of Al-chelated gelatin (ACG) prepared by sol-gel method in the ITO/ACG/ITO structure, a highly transparent resistive random access memory (RRAM) was obtained. The transmittance of the fabricated device is approximately 83% at 550 nm while that of Al/gelatin/ITO is opaque. As to the ITO/gelatin/ITO RRAM, no resistive switching behavior can be seen. The ITO/ACG/ITO RRAM shows high ON/OFF current ratio (>105), low operation voltage, good uniformity, and retention characteristics at room temperature and 85 °C. The mechanism of the ACG-based memory devices is presented. The enhancement of these electrical properties can be attributed to the chelate effect of Al ions with gelatin. Results show that transparent ACG-based memory devices possess the potential for next-generation resistive memories and bio-electronic applications

  3. Comparative analysis of the cytotoxicity of substituted (phenylglyoxal bis(4-methyl-3-thiosemicarbazone)) copper (II) chelates.

    Science.gov (United States)

    Coats, E A; Milstein, S R; Holbein, G; McDonald, J; Reed, R; Petering, H G

    1976-01-01

    Seven para-substituted [phenylglyoxal bis(4-methyl-3-thiosemicarbazone)]copper (II) chelates (12-18) have been designed, synthesized, and tested for their ability to inhibit the respiration of rat liver slices as a normal cell model and Ehrlich ascites cells as a tumor cell model. Relationships between chemical structure and respiratory inhibition are described on a quantitative basis using substituent contants (pi, Es, and sigmap) by computerized multiparameter regression analyses. The correlations indicate that changes in Es have the largest effect on liver slice toxicity of chelates while pi and sigmap account for most of the variation in toxicity to ascites cells. A comparative analysis strongly suggests that electron-donating substituents with greater water solubility should increase cytotoxicity to ascites cells at the expense of cytotoxicity to the rat liver cells. The predictions of the equations were checked by synthesizing and testing an additional derivative. The results strengthen the initial predictions. PMID:1246035

  4. Efficacy of chelating agents for treatment of acute uranium intoxication in rats

    International Nuclear Information System (INIS)

    Chelating agents (8102, 7601, 811, 7603, 8307, DTPA) were tested for treatment of acute uranium intoxication in rats. All phenolic chelating agents distinctively increased removal of uranium when they were injected immediately after intoxication of uranyl nitrate. 8102 was the best of them on removing uranium. After a single i.m. injection of 8102 at dose of 500 mg/kg, the excretion of uranium in the urine was 2.9 times higher than that for control, and the retention of uranium in kidneys was their 29%. When 8102 was administered 1 h before and up to 4 h after intoxication, it markedly increased the removal of uranium. When 8102 was administered to rats 1 h before intoxication, the histological lesion in kidneys was only a slight hydropic degeneration of the tubule epithelial cells. On the contrary, there wa a severe necrosis of the tubule epithelial cells in kidneys for controls

  5. The Structural Basis of Action of Vanadyl (VO(2+)) Chelates in Cells.

    Science.gov (United States)

    Makinen, Marvin W; Salehitazangi, Marzieh

    2014-11-01

    Much emphasis has been given to vanadium compounds as potential therapeutic reagents for the treatment of diabetes mellitus. Thus far, no vanadium compound has proven efficacious for long-term treatment of this disease in humans. Therefore, in review of the research literature, our goal has been to identify properties of vanadium compounds that are likely to favor physiological and biochemical compatibility for further development as therapeutic reagents. We have, therefore, limited our review to those vanadium compounds that have been used in both in vivo experiments with small, laboratory animals and in in vitro studies with primary or cultured cell systems and for which pharmacokinetic and pharmacodynamics results have been reported, including vanadium tissue content, vanadium and ligand lifetime in the bloodstream, structure in solution, and interaction with serum transport proteins. Only vanadyl (VO(2+)) chelates fulfill these requirements despite the large variety of vanadium compounds of different oxidation states, ligand structure, and coordination geometry synthesized as potential therapeutic agents. Extensive review of research results obtained with use of organic VO(2+)-chelates shows that the vanadyl chelate bis(acetylacetonato)oxidovanadium(IV) [hereafter abbreviated as VO(acac)2], exhibits the greatest capacity to enhance insulin receptor kinase activity in cells compared to other organic VO(2+)-chelates, is associated with a dose-dependent capacity to lower plasma glucose in diabetic laboratory animals, and exhibits a sufficiently long lifetime in the blood stream to allow correlation of its dose-dependent action with blood vanadium content. The properties underlying this behavior appear to be its high stability and capacity to remain intact upon binding to serum albumin. We relate the capacity to remain intact upon binding to serum albumin to the requirement to undergo transcytosis through the vascular endothelium to gain access to target tissues in

  6. Solution mining dawsonite from hydrocarbon containing formations with a chelating agent

    Science.gov (United States)

    Vinegar, Harold J.

    2009-07-07

    A method for treating an oil shale formation comprising dawsonite includes providing heat from one or more heaters to the formation to heat the formation. Hydrocarbon fluids are produced from the formation. At least some dawsonite in the formation is decomposed with the provided heat. A chelating agent is provided to the formation to dissolve at least some dawsonite decomposition products. The dissolved dawsonite decomposition products are produced from the formation.

  7. Quantification of thorium in uranium matrix by chelation ion chromatography (CIC)

    International Nuclear Information System (INIS)

    The present work describes an optimized procedure for the determination of thorium in uranium oxide by chelation ion chromatography technique. The method involves a two stage separation of matrix element by employing solvent extraction and ion exchange. Chromatographically thorium has been separated from the traces of other metallic impurities and the matrix element which is expected to be present in trace quantity even after employing prior separations. (author)

  8. Iron chelation therapy in transfusion-dependent thalassemia patients: current strategies and future directions

    OpenAIRE

    Saliba AN; Harb AR; Taher AT

    2015-01-01

    Antoine N Saliba, Afif R Harb, Ali T Taher Department of Internal Medicine, Division of Hematology/Oncology, American University of Beirut, Beirut, Lebanon Abstract: Transfusional iron overload is a major target in the care of patients with transfusion-dependent thalassemia (TDT) and other refractory anemias. Iron accumulates in the liver, heart, and endocrine organs leading to a wide array of complications. In this review, we summarize the characteristics of the approved iron chelators, def...

  9. Selective Chemical Labeling of Proteins with Small Fluorescent Molecules Based on Metal-Chelation Methodology

    OpenAIRE

    Nobuaki Soh

    2008-01-01

    Site-specific chemical labeling utilizing small fluorescent molecules is a powerful and attractive technique for in vivo and in vitro analysis of cellular proteins, which can circumvent some problems in genetic encoding labeling by large fluorescent proteins. In particular, affinity labeling based on metal-chelation, advantageous due to the high selectivity/simplicity and the small tag-size, is promising, as well as enzymatic covalent labeling, thereby a variety of novel methods have been stu...

  10. Switch from antagonist to agonist after addition of a DOTA chelator to a somatostatin analog

    Energy Technology Data Exchange (ETDEWEB)

    Reubi, Jean Claude; Cescato, Renzo; Waser, Beatrice [University of Berne, Division of Cell Biology and Experimental Cancer Research, Institute of Pathology, PO Box 62, Berne (Switzerland); Erchegyi, Judit; Rivier, Jean E. [The Salk Institute for Biological Studies, The Clayton Foundation Laboratories for Peptide Biology, La Jolla, CA (United States)

    2010-08-15

    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{sub 1}-sst{sub 5}) binding affinity using receptor autoradiography. Moreover, they were tested functionally for their ability to affect sst{sub 2} and sst{sub 3} internalization in vitro in HEK293 cells stably expressing the human sst{sub 2} or sst{sub 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{sub 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{sub 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{sub 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.)

  11. Theoretical study, and infrared and Raman spectra of copper(II) chelated complex with dibenzoylmethane

    DEFF Research Database (Denmark)

    Nekoei, A.-R.; Vakili, M.; Hakimi-Tabar, M.;

    2014-01-01

    There are some discrepancies in both the vibrational assignments and in the metal-ligand (M-L) bond strengths predicted in the previous studies on the copper (II) chelated complex of dibenzoylmethane, Cu(dbm)2. Also, there is a lack of theoretical structure, Raman spectrum and full vibrational as...... in Cu(dbm)2 are concluded to be higher than those in Cu(acac)2. The calculated geometries and vibrational results are in good agreement with the experimental data....

  12. Curcumin Inhibits Growth of Saccharomyces cerevisiae through Iron Chelation ▿ ††

    OpenAIRE

    Minear, Steven; O'Donnell, Allyson F.; Ballew, Anna; Giaever, Guri; Nislow, Corey; Stearns, Tim; Martha S Cyert

    2011-01-01

    Curcumin, a polyphenol derived from turmeric, is an ancient therapeutic used in India for centuries to treat a wide array of ailments. Interest in curcumin has increased recently, with ongoing clinical trials exploring curcumin as an anticancer therapy and as a protectant against neurodegenerative diseases. In vitro, curcumin chelates metal ions. However, although diverse physiological effects have been documented for this compound, curcumin's mechanism of action on mammalian cells remains un...

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

    OpenAIRE

    Durjoy Majumder; Sayan Mukherjee

    2013-01-01

    Arsenic contamination of ground water has become a global problem affecting specially, south-east Asian countries like Bangladesh and eastern parts of India. It also affects South America and some parts of the US. Different organs of the physiological system are affected due to contamination of inorganic arsenic in water. Animal studies with different chelators are not very conclusive as far as the multi/differential organ effect(s) of arsenic is concerned. Our docking study establishes the m...

  14. The Management of Iron Chelation Therapy: Preliminary Data from a National Registry of Thalassaemic Patients

    OpenAIRE

    Adriana Ceci; Laura Mangiarini; Mariagrazia Felisi; Franco Bartoloni; Angela Ciancio; Marcello Capra; Domenico D'Ascola; Paolo Cianciulli; Aldo Filosa

    2011-01-01

    Thalassaemia and other haemoglobinopathies constitute an important health problem in Mediterranean countries, placing a tremendous emotional, psychological, and economic burden on their National Health systems. The development of new chelators in the most recent years had a major impact on the treatment of thalassaemia and on the quality of life of thalassaemic patients. A new initiative was promoted by the Italian Ministry of Health, establishing a Registry for thalassaemic patients to serve...

  15. Chelators influenced synthesis of chitosan-carboxymethyl cellulose microparticles for controlled drug delivery

    Science.gov (United States)

    Samrot, Antony V.; Akanksha; Jahnavi, Tatipamula; Padmanaban, S.; Philip, Sheryl-Ann; Burman, Ujjala; Rabel, Arul Maximus

    2016-07-01

    In this study, polyphenolic curcumin is entrapped within microcomposites made of biopolymers chitosan (CS) and carboxymethyl cellulose (CMC) formulated by ionic gelation method. Here, different concentrations of two chelating agents, barium chloride and sodium tripolyphosphate, are used to make microcomposites. Thus, the synthesized microparticles were characterized by FTIR, and their surface morphology was studied by SEM. Drug encapsulation efficiency and the drug release kinetics of CS-CMC composites are also studied. The produced microcomposites were used to study antibacterial activity in vitro.

  16. 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

  17. Lutetium-177 and iodine-131 loaded chelating polymer microparticles intended for radioembolization of liver malignancies

    Czech Academy of Sciences Publication Activity Database

    Hrubý, Martin; Škodová, Michaela; Macková, Hana; Skopal, Jan; Tomeš, Marek; Kropáček, Martin; Zimová, Jana; Kučka, Jan

    2011-01-01

    Roč. 71, č. 12 (2011), s. 1155-1159. ISSN 1381-5148 R&D Projects: GA ČR GPP207/10/P054; GA MŠk 1M0505 Institutional research plan: CEZ:AV0Z40500505; CEZ:AV0Z10480505 Keywords : macroporous chelating beads * radioembolization * quinoline-8-ol Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.479, year: 2011

  18. Neurotensin(8-13) analogue: radiolabeling and biological evaluation using different chelators

    International Nuclear Information System (INIS)

    Introduction: Several strategies on the development of radiopharmaceuticals have been employed. Bifunctional chelators seem to be a promising approach since high radiochemical yields as well as good in vitro and in vivo stability have been achieved. To date, neurotensin analogs have been radiolabeled using the 99mTc-carbonyl approach and none was described employing the bifunctional chelating agent technique. Aim: The purpose of this study was to evaluate the radiochemical and biological behaviour of NT(8-13) analogue radiolabeled with 99mTc, using HYNIC and NHS-S-acetyl-MAG3 as chelator agents. Methods: Radiolabeling, in vitro stability toward cysteine and glutathione, partition coefficient and plasma protein binding were assessed for both radioconjugates. Biodistribution in healthy Swiss mice were carried out in order to evaluate the biological behaviour of the radiocomplexes. Results: Radiochemical yields were higher than 97% and no apparent instability toward transchelant agents was observed for both radioconjugates. A higher lipophilic character was observed for the radioconjugate labeled via MAG3. The chelators seem to have no effect on the percentage of the radioconjugate bound to plasma proteins. A similar biological pattern was observed for both radioconjugates. Total blood, bone and muscle values revealed a slightly slower clearance for the radiocomplex labeled via MAG3. Moreover, a remarkable liver and intestinal uptake was observed for the radiocomplex labeled via MAG3 even at the later time points studied. Conclusion: The high radiochemical yields achieved and the similar in vivo pattern found for both radioconjugates make them potential candidates for imaging tumors using nuclear medicine techniques.

  19. Bioavailability assessment of metals chelated as proteinates using the Ussing Chamber Model

    OpenAIRE

    Piva, G.; G. Cavanna; G. Casadei; A. Piva

    2011-01-01

    Preparation of proteinates by hydrolysis of organic matter produces a blend of different proteins, and may likely result in the chelation of trace elements. Often this process results in an increased bioavailability of minerals, leading to a higher absorption rate than inorganic salts (Cao et al., 2000; Uchida et al., 2001; Bailey et al., 2001; Guo et al., 2001). Usually trace elements uptake takes place along the small intestine, mainly jejunum (Tapia et al., 1996; Arredondo et al., 2000), e...

  20. Flavonoids function as antioxidants: by scavenging reactive oxygen species or by chelating iron?

    International Nuclear Information System (INIS)

    Flavonoids have been reported to exhibit strong antioxidative activity. In the present work, a systematic mechanistic study has been performed on five flavonoids (baicalin, hesperidin, naringin, quercetin and rutin) selected according to their structural characteristics. The experimental results reveal that flavonoids function as antioxidant mainly by chelating iron ions and by scavenging peroxyl radicals whereas their OH radical scavenging effect is much less important. (author)

  1. Flavonoids function as antioxidants: by scavenging reactive oxygen species or by chelating iron?

    Energy Technology Data Exchange (ETDEWEB)

    Wuguo Deng; Xingwang Fang; Jilan Wu [Peking Univ., Technical Physics Dept., Beijing (China)

    1997-09-01

    Flavonoids have been reported to exhibit strong antioxidative activity. In the present work, a systematic mechanistic study has been performed on five flavonoids (baicalin, hesperidin, naringin, quercetin and rutin) selected according to their structural characteristics. The experimental results reveal that flavonoids function as antioxidant mainly by chelating iron ions and by scavenging peroxyl radicals whereas their OH radical scavenging effect is much less important. (author).

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

    OpenAIRE

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

    2012-01-01

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

  3. Overview of guidelines on iron chelation therapy in patients with myelodysplastic syndromes and transfusional iron overload

    OpenAIRE

    Gattermann, Norbert

    2008-01-01

    Between 2002 and 2008, a number of consensus statements and guidelines were developed by various groups around the world to educate healthcare professionals on the treatment of myelodysplastic syndromes (MDS), including the management of transfusional iron overload with iron chelation therapy. Guidelines have been developed by The Italian Society of Hematology, The UK MDS Guidelines Group, The Nagasaki Group, The National Comprehensive Cancer Network, and The MDS Foundation. These guidelines ...

  4. Chelator-Induced Dispersal and Killing of Pseudomonas aeruginosa Cells in a Biofilm†

    OpenAIRE

    Banin, Ehud; Brady, Keith M.; Greenberg, E. Peter

    2006-01-01

    Biofilms consist of groups of bacteria attached to surfaces and encased in a hydrated polymeric matrix. Bacteria in biofilms are more resistant to the immune system and to antibiotics than their free-living planktonic counterparts. Thus, biofilm-related infections are persistent and often show recurrent symptoms. The metal chelator EDTA is known to have activity against biofilms of gram-positive bacteria such as Staphylococcus aureus. EDTA can also kill planktonic cells of Proteobacteria like...

  5. Degradation of the Ferric Chelate of EDTA by a Pure Culture of an Agrobacterium sp

    OpenAIRE

    Lauff, John J.; Steele, D. Bernie; Coogan, Louise A.; Breitfeller, James M.

    1990-01-01

    A pure culture of an Agrobacterium sp. (deposited as ATCC 55002) that mineralizes the ferric chelate of EDTA (ferric-EDTA) was isolated by selective enrichment from a treatment facility receiving industrial waste containing ferric-EDTA. The isolate grew on ferric-EDTA as the sole carbon source at concentrations exceeding 100 mM. As the degradation proceeded, carbon dioxide, ammonia, and an unidentified metabolite(s) were produced; the pH increased, and iron was precipitated from solution. The...

  6. Effects of Iron Chelators on the Formation and Development of Aspergillus fumigatus Biofilm.

    Science.gov (United States)

    Nazik, Hasan; Penner, John C; Ferreira, Jose A; Haagensen, Janus A J; Cohen, Kevin; Spormann, Alfred M; Martinez, Marife; Chen, Vicky; Hsu, Joe L; Clemons, Karl V; Stevens, David A

    2015-10-01

    Iron acquisition is crucial for the growth of Aspergillus fumigatus. A. fumigatus biofilm formation occurs in vitro and in vivo and is associated with physiological changes. In this study, we assessed the effects of Fe chelators on biofilm formation and development. Deferiprone (DFP), deferasirox (DFS), and deferoxamine (DFM) were tested for MIC against a reference isolate via a broth macrodilution method. The metabolic effects (assessed by XTT [2,3-bis[2-methoxy-4-nitro-5-sulfophenyl]-2H-tetrazolium-5-carboxanilide inner salt]) on biofilm formation by conidia were studied upon exposure to DFP, DFM, DFP plus FeCl3, or FeCl3 alone. A preformed biofilm was exposed to DFP with or without FeCl3. The DFP and DFS MIC50 against planktonic A. fumigatus was 1,250 μM, and XTT gave the same result. DFM showed no planktonic inhibition at concentrations of ≤2,500 μM. By XTT testing, DFM concentrations of biofilms forming in A. fumigatus or preformed biofilms (P biofilm formation (P Biofilm formation with 625 μM DFP plus any concentration of FeCl3 was lower than that in the controls (P biofilms, DFP in the range of ≥625 to 1,250 μM was inhibitory compared to the controls (P biofilm formation (P biofilm increased with 2,500 μM FeCl3 only (P biofilms of A. fumigatus clinical isolates to DFP were noted. In conclusion, iron stimulates biofilm formation and preformed biofilms. Chelators can inhibit or enhance biofilms. Chelation may be a potential therapy for A. fumigatus, but we show here that chelators must be chosen carefully. Individual isolate susceptibility assessments may be needed. PMID:26239975

  7. Preclinical evaluation of somatostatin analogs bearing two macrocyclic chelators for high specific activity labeling with radiometals

    International Nuclear Information System (INIS)

    Radiometallated analogues of the regulatory peptide somatostatin are of interest in the in vivo localization and targeted radiotherapy of somatostatin receptor-overexpressing tumors. An important aspect of their use in vivo is a fast and efficient labeling (complexation) protocol for radiometals along with a high specific activity. We describe in this manuscript synthetic methods for the coupling of two chelators (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid = DOTA) to the bioactive peptide [Tyr3,Thr8]-octreotide (TATE) in order to increase the specific activity (radioactivity in Bq per mole peptide). The full chelator-linker-peptide conjugate was assembled on solid support using standard Fmoc chemistry. Two DOTA-chelators were linked to the peptide using lysine or N,N'-bis(3-aminopropyl)-glycine (Apg); in addition, pentasarcosine (Sar5) was used as a spacer between the chelators and the peptide to probe its influence on biology and pharmacology. Complexation rates with In3+ and Y3+ salts and the corresponding radiometals were high, the bis-DOTA-derivatives showed higher complexation rates and gave higher specific activity than DOTA-TATE. Pharmacological and biological data of the complexed molecules did not show significant differences if compared to the parent peptide [111/natIn-DOTA]-TATE except for [(111/natIn-DOTA)2-Apg]-TATE which showed a lower binding affinity and rate of internalization into tumor cells. The biodistribution of [(111/natIn-DOTA)-Lys(111/natIn-DOTA)]-TATE in the rat tumor model (AR4-2J) showed a high and specific (as shown by a blocking experiment) tracer uptake in somatostatin receptor-positive tissue but a lower tumor uptake compared to [111/natIn-DOTA]-TATE. (orig.)

  8. Protection against SR 4233 (tirapazamine) aerobic cytotoxicity by the metal chelators desferrioxamine and tiron

    International Nuclear Information System (INIS)

    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

  9. Switch from antagonist to agonist after addition of a DOTA chelator to a somatostatin analog

    International Nuclear Information System (INIS)

    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 (sst1-sst5) binding affinity using receptor autoradiography. Moreover, they were tested functionally for their ability to affect sst2 and sst3 internalization in vitro in HEK293 cells stably expressing the human sst2 or sst3 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 sst2 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 sst3 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 sst3 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.)

  10. Synthesis of a Functional Metal-Chelating Polymer and Steps towards Quantitative Mass Cytometry Bioassays

    OpenAIRE

    Majonis, Daniel; Herrera, Isaac; Ornatsky, Olga; Schulze, Maren; Lou, Xudong; Soleimani, Mohsen; Nitz, Mark; Mitchell A. Winnik

    2010-01-01

    We describe the synthesis and characterization of metal-chelating polymers with a degree of polymerization of 67 and 79, high DTPA functionality, Mw/Mn ≤ 1.17, and a maleimide as an orthogonal functional group for conjugation to antibodies. The polymeric disulfide form of the DPn = 79 DTPA polymer was analyzed by thermogravimetric analysis to determine moisture and sodium-ion content, and by isothermal titration calorimetry (ITC) to determine the Gd3+ binding capacity. These results showed ea...

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

    International Nuclear Information System (INIS)

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2000-12-01

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

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

    International Nuclear Information System (INIS)

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

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

    Directory of Open Access Journals (Sweden)

    Durjoy Majumder

    2013-01-01

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

  15. Modelling studies in aqueous solution of lanthanide (III) chelates designed for nuclear magnetic resonance biomedical applications

    Science.gov (United States)

    Henriques, E. S.; Geraldes, C. F. G. C.; Ramos, M. J.

    Molecular dynamics simulations and complementary modelling studies have been carried out for the [Gd(DOTA)·(H2O)]- and [Tm(DOTP)]5- chelates in aqueous media, to provide a better understanding of several structural and dynamical properties of these versatile nuclear magnetic resonance (NMR) probes, including coordination shells and corresponding water exchange mechanisms, and interactions of these complexes with alkali metal ions. This knowledge is of key importance in the areas of 1H relaxation and shift reagents for NMR applications in medical diagnosis. A new refinement of our own previously developed set of parameters for these Ln(III) chelates has been used, and is reported here. Calculations of water mean residence times suggest a reassessment of the characterization of the chelates' second coordination shell, one where the simple spherical distribution model is discarded in favour of a more detailed approach. Na+ probe interaction maps are in good agreement with the available site location predictions derived from 23Na NMR shifts.

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

    Science.gov (United States)

    Xu, Ying; Chen, Yu

    2015-07-01

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

  17. Disaggregation ability of different chelating molecules on copper ion-triggered amyloid fibers.

    Science.gov (United States)

    Zhu, Linyi; Han, Yuchun; He, Chengqian; Huang, Xu; Wang, Yilin

    2014-08-01

    Dysfunctional interaction of amyloid-β (Aβ) with excess metal ions is proved to be related to the etiology of Alzheimer's disease (AD). Using metal-binding compounds to reverse metal-triggered Aβ aggregation has become one of the potential therapies for AD. In this study, the ability of a carboxylic acid gemini surfactant (SDUC), a widely used metal chelator (EDTA), and an antifungal drug clioquinol (CQ) in reversing the Cu(2+)-triggered Aβ(1-40) fibers have been systematically studied by using turbidity essay, BCA essay, atomic force microscopy, transmission electron microscopy, and isothermal titration microcalorimetry. The results show that the binding affinity of Cu(2+) with CQ, SDUC, and EDTA is in the order of CQ > EDTA > SDUC, while the disaggregation ability to Cu(2+)-triggered Aβ(1-40) fibers is in the order of CQ > SDUC > EDTA. Therefore, the disaggregation ability of chelators to the Aβ(1-40) fibers does not only depend on the binding affinity of the chelators with Cu(2+). Strong self-assembly ability of SDUC and π-π interaction of the conjugate group of CQ also contributes toward the disaggregation of the Cu(2+)-triggered Aβ(1-40) fibers and result in the formation of mixed small aggregates. PMID:25051063

  18. Introducing new 99m-Tc-bifunctional radiopharmaceutical containing dithiosemicarbazone chelate group

    International Nuclear Information System (INIS)

    In our attempt to develop 99m-Tc-Bifunctional Radiopharmaceuticals (BR) of biomolecules, our interest has been focussed on the di-thiosemicarbazone chelating group (DTS); its coordination moiety allows a 1:1 complex with a tetravalent TcO2+, generating a neutral chelate of great stability and compactness. For ligand containing S N coordination, satisfactory labeling has been achieved at pH 5-6, in the presence of Sn-Resin. Based on the above mentioned, the use of DTS is tested in two different modalities by selecting glucose and albumin as the biomolecules of interest. The synthesis of a glucosone-1,2-bis (thiosemicarbazone) (Glu-DTS) and upon its labelling, the 99m-Tc-Glu-DTS was tested in animals. Scintigraphic studies revealed high activity in the brain and heart. This result offered strong support for the use of DTS as a bifunctional chelating agent (BCA). DTS-COOH and DTS-NH2 were synthesized for the coupling with biomolecules. As a first trial, they were coupled with albumin and their functionality proven. The results gathered provided conclusive evidence for the remarkable characteristic of DTS as a basic structure for the development of 99m-Tc-RP

  19. Chelating effect in short polymers for the design of bidentate binders of increased affinity and selectivity

    Science.gov (United States)

    Fortuna, Sara; Fogolari, Federico; Scoles, Giacinto

    2015-10-01

    The design of new strong and selective binders is a key step towards the development of new sensing devices and effective drugs. Both affinity and selectivity can be increased through chelation and here we theoretically explore the possibility of coupling two binders through a flexible linker. We prove the enhanced ability of double binders of keeping their target with a simple model where a polymer composed by hard spheres interacts with a spherical macromolecule, such as a protein, through two sticky spots. By Monte Carlo simulations and thermodynamic integration we show the chelating effect to hold for coupling polymers whose radius of gyration is comparable to size of the chelated particle. We show the binding free energy of flexible double binders to be higher than that of two single binders and to be maximized when the binding sites are at distances comparable to the mean free polymer end-to-end distance. The affinity of two coupled binders is therefore predicted to increase non linearly and in turn, by targeting two non-equivalent binding sites, this will lead to higher selectivity.

  20. The determination of the rate of conjugation immunoglobuline with bifunctional chelator

    Science.gov (United States)

    Málek, Z.; Miler, V.; Budský, F.

    2006-01-01

    The work was performed under the GACR project: "Technology of preparation of radionuclides and their labelled compounds for nuclear medicine and pharmacy with the use of the reactor LVR-15" reg. no. 104/03/0499. Imaging of cell’s antigens with the use of labelled immunoglobulines allows imaging of specific receptors on cell membrane and specific tumours. It is necessary to carry out the labelling of the immunoglobulines with radionuclides of suitable physical properties, which form cations (e.g., 111In, 90Y, 177Lu) that form very strong chelates of sufficiently high stability constant preventing the dissociation of complexes or the radionuclide under “in-vivo” conditions. The immunoglobuline must be conjugated with the bifunctional chelator (BCH), which contains both chelating unit and reactive group for binding to the immunoglobuline. In our laboratory we have conjugated human IgG and monoclonal antibody CD20 with diethylenetriamine pentaacetic acid dianhydride (cDTPAA). Radionuclides 90Y and 177Lu prepared on the LVR-15 reactor in NRI Rez were used for labelling. After conjugation and labelling the yields in relation to the amount of isotopic carrier have been determined.

  1. BIOPRODUCTIVE AND ECONOMIC EFFECT OF THE CHELATED MINERAL PREMIX GIVEN TO FATTENING STEERS

    Directory of Open Access Journals (Sweden)

    DORICA VOICU

    2013-12-01

    Full Text Available The experiment investigated the effect of the different dietary levels of the mineral premix based on phosphate frittes with chelated bioelements on the weight gain, feed conversion ratio, and economic efficiency of the Brown fattening steers. The animals were assigned to 3 experimental groups: group 1 with 0.1%, group 2 with 0.5% and group 3 with 1% chelated mineral premix in the compound feed next to the corn silage (basal diet. The ingested feeds were similar among the 3 groups, both for the bulk feed (free access and for the compound feed (CF as such or as dry matter. Group 1 had an intake of 9.43 kg, group 2 had 9.37 kg and group 3 had 9.42 kg/steer/day, which represents 6.65; 7.71 and 6.72 kg total DM/steer/day. The similar feed intakes produced similar gains: 1348 g in group 1, 1368 g in group 2 and 1347 g /steer/day in group 3, the differences not being statistically significant (P > 0.05. No significant differences were documented in the dry matter, energy and protein intake for the retention of one kg body weight. The use of the dietary chelated mineral premix in different proportions (0.1, 0.5 and 1% given to fattening steers was economically efficient only for the 0.1% rate of inclusion.

  2. Europium chelate-loaded liposomes: a tool for the study of binding and integrity of liposomes.

    Science.gov (United States)

    Orellana, A; Laukkanen, M L; Keinänen, K

    1996-10-01

    Using the biotin-streptavidin interaction as a model, we investigated the suitability of lanthanide chelates as encapsulated liposomal labels in liposome-based binding assays. Large unilamellar phospholipid:cholesterol liposomes containing europium-DTPA chelate and biotinylated phosphatidylethanolamine were prepared by detergent dialysis. The resulting Eu-liposomes ([symbol: see text] 120 nm) bound specifically to streptavidin in microtiter wells as measured by time-resolved fluorometric assay (TRF). The intensity of fluorescence released from the bound liposomes was dependent on the concentration of biotin in the liposome membrane, the concentration of europium entrapped in the liposomes, the incubation time and the amount of liposomes used in the assay. The sensitivity of the TRF assay allowed the detection of binding of attomole quantities of liposomes. The streptavidin-immobilised liposomes subjected to porcine pancreatic phospholipase A2 (EC 3.1.1.4) and detergents displayed a dose-dependent release of the encapsulated europium. Lanthanide-chelate-liposomes should prove useful for studies addressing binding and stability of liposomes. PMID:8865811

  3. New series of chelated organochromium(III) complexes. [1,4,8,12-Tetraazacyclopentaedecane

    Energy Technology Data Exchange (ETDEWEB)

    Samuels, G.J.

    1979-01-01

    A kinetic and mechanistic study of the preparation of a new family of chelated organochromium(III) complexes was completed. These species were formed from organic halides and (1,4,8,12 tetraazacyclopentadecane) chromium(II) by a mechanism which involves initial halogen atom abstraction followed by subsequent radical capture by another Cr(II) complex. The rates of reaction follow the pattern expected for a S/sub H/2 process, 3/sup 0/ > 2/sup 0/ > 1/sup 0/ and I > Br > Cl. These organochromium(III) chelate complexes have the trans configuration. Electrophilic cleavage reactions by mercuric and methylmercuric ions were studied. These reactions proceed by a S/sub E/2 (open) mechanism with the reaction rates being approx. 100 times slower for the chelated species. The activation parameters were determined for five reactions. The crystal structure of (trans-chloroaquo(1,4,8,12-tetraazacyclopentadecane)chromium(III))diiodide-dihydrate is also reported. The macrocycle assumes the lowest energy conformation as predicted by strain energy calculations.

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

    Directory of Open Access Journals (Sweden)

    Mona Mosayebnia

    2014-01-01

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

  5. 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.)

  6. Deferoxamine as a chelator for {sup 67}Ga in the preparation of antibody conjugates

    Energy Technology Data Exchange (ETDEWEB)

    Govindan, Serengulam V. [Immunomedics, Inc., Morris Plains, NJ 07950 (United States); Michel, Rosana B. [Center for Molecular Medicine and Immunology, Belleville, NJ 07109 (United States); Griffiths, Gary L. [Immunomedics, Inc., Morris Plains, NJ 07950 (United States); Goldenberg, David M. [Center for Molecular Medicine and Immunology, Belleville, NJ 07109 (United States); Mattes, M. Jules [Center for Molecular Medicine and Immunology, Belleville, NJ 07109 (United States)]. E-mail: mjmattes@gscancer.org

    2005-07-01

    {sup 67}Ga antibodies (Abs) have been shown to be effective agents for single-cell killing due to the Auger electrons emitted, but their specific activities have not been as high as desired. We therefore evaluated deferoxamine (DFO) as a chelator, as opposed to the cyclic chelator NOTA, which was used previously. Use of DFO for Ab conjugation to {sup 67}Ga was reported previously by several laboratories. DFO was conjugated to Abs by two methods, one using Ablysine conjugation and another using mild reduction of Abs to generate thiols in the hinge region. Labeling with {sup 67}Ga was efficient, and the specific activities obtained under nonoptimized conditions were twice as high as those achieved previously. However, analysis of these conjugates revealed two problems that appear to prevent their further development. First, the stability was inadequate for the 3-day half-life of the nuclide. Second, the labels were poorly retained within cells after Ab internalization and catabolism. Also, it was found that stability was significantly affected by the incubation buffer used: buffers lacking physiological concentrations of divalent cations Ca and Mg resulted in much lower stability than buffers including them. In conclusion, DFO does not seem to be a suitable chelator for {sup 67}Ga conjugation for our purposes.

  7. Synthesis of chelating agents for actinium 225 complexation and its application in radioimmunotherapy

    International Nuclear Information System (INIS)

    Immunotherapy with radiolabeled antibodies should allow fairly specific targeting of certain cancers. However, iodine 131 may not be the best isotope for tumor therapy because of its limited specific activity, low beta-energy, relatively long half life and strong gamma emission. Another approach to improve therapeutic efficacy is the use of replacement isotopes with better physical properties. Chelator that can hold radio-metals with high stability under physiological conditions are essential to avoid excessive damage to non-target cells; Moreover, the development of new bifunctional chelating agents is essential for this purpose. Accordingly, our efforts have been directed, for several years, to the synthesis of original chelating agents likely to form stable complexes in vivo with the numerous potential candidates for such applications. Therefore, we have developed a new simple and efficient synthesis pathway of 2-(4-iso-thio-cyanate-benzyl)-1,4,7,10,13,16- hexa-aza-cyclo-hexadecane- 1,4,7,10,13,16-hexa-acetic acid, though functionalized on the cycle by a termination allowed coupling to an antibody or any other biological substance such as a hapten. (author)

  8. Effect of the Alkyl Chain Length on the Adsorption Properties of Malonamide Chelating Resins

    International Nuclear Information System (INIS)

    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 HNO3, Acid, and 3 M NaNO3 + 0.05 M HNO3, 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

  9. 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. PMID:27109868

  10. Public Health Department Response to Mercury Poisoning: The Importance of Biomarkers and Risks and Benefits Analysis for Chelation Therapy

    OpenAIRE

    McKay, Charles A.

    2013-01-01

    Chelation therapy is often used to treat mercury poisoning. Public health personnel are often asked about mercury toxicity and its treatment. This paper provides a public health department response to use of a mercury-containing cosmetic in Minnesota, a perspective on two unpublished cases of chelation treatment for postulated mercury toxicity, and comments on the use of a nonsystemic treatment for removal of mercury following the Iraqi seed coat poisoning incident. Physicians should evaluate...

  11. Rapid iron loading in a pregnant woman with transfusion-dependent thalassemia after brief cessation of iron chelation therapy

    OpenAIRE

    Farmaki, Kallistheni; Gotsis, Efstathios; Tzoumari, Ioanna; Berdoukas, Vasilios

    2008-01-01

    In general, in women with transfusion-dependent thalassemia, during pregnancy, iron chelation therapy is ceased. We report a splenectomized patient, who was an excellent complier with chelation therapy, who before embarking on a pregnancy showed no evidence of iron overload, with normal cardiac, thyroid function and glucose metabolism. Laboratory findings showed ferritin 67 μg/L, myocardial T2* of 34 ms and liver magnetic resonance imaging (MRI) liver iron concentration of 1 mg/g dry weight. ...

  12. INFLUENCE OF IRON CHELATION ON R1 AND R2 CALIBRATION CURVES IN GERBIL LIVER AND HEART

    OpenAIRE

    Wood, John C.; AGUILAR, MICHELLE; Otto-Duessel, Maya; Nick, Hanspeter; Nelson, Marvin D.; Moats, Rex

    2008-01-01

    MRI is gaining increasing importance for the noninvasive quantification of organ iron burden. Since transverse relaxation rates depend on iron distribution as well as iron concentration, physiologic and pharmacologic processes that alter iron distribution could change MRI calibration curves. This paper compares the effect of three iron chelators, deferoxamine, deferiprone, and deferasirox on R1 and R2 calibration curves according to two iron loading and chelation strategies. 33 Mongolian gerb...

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

    OpenAIRE

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

    2014-01-01

    Objective. This prospective pilot study aimed at evaluating the effects of therapy with antioxidant compounds (Cellfood, and other antioxidants) on patients affected by neurodegenerative diseases (ND), who displayed toxic metal burden and were subjected to chelation treatment with the chelating agent calcium disodium ethylenediaminetetraacetic acid (CaNa2EDTA or EDTA). Methods. Two groups of subjects were studied: (a) 39 patients affected by ND and (b) 11 subjects unaffected by ND (controls)....

  14. FORMULATION OF ORAL IRON CHELATOR DEFERASIROX IN A NEW STABLE AND SUITABLE DOSAGE FORM WITH OPTIMUM RELEASE PARAMETERS

    OpenAIRE

    Yugandhar KM, Vasanth PM, Suresh K, Ramesh T, Ramesh Malothu*

    2013-01-01

    Regular blood transfusions for patients with chronic anemia inevitably lead to iron overload in the blood. The cumulative effect of iron overload may cause morbidity and mortality if not treated with chelator. Oral iron chelator, Deferasirox used in the treatment of β-thalessemia is designed and developed into a stable solid oral dispersion dosage form to deliver with optimum concentration of the drug at desired site at specific time comparable to the innovator product. The excipients were fo...

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

    OpenAIRE

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

    2011-01-01

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

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

    OpenAIRE

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

    2001-01-01

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

  17. 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. PMID:25985711

  18. Modulation of chelating factors, trace minerals and their estimated bioavailability in Italian and African sorghum (Sorghum bicolor (L.) Moench) porridges

    OpenAIRE

    Proietti, I.; Mantovani, A.; Mouquet Rivier, Claire; Guyot, Jean-Pierre

    2013-01-01

    Factors able to modulate chelating factors, trace minerals and their bioavailability were investigated in porridges of five sorghum (Sorghum bicolor (L.) Moench) varieties: from Nigeria, Senegal, Burkina Faso and two from Italy. Effects of variety and traditional fermentation and cooking were assessed on iron-binding phenolic groups, phytates and iron and zinc content and bioavailability. Chelating factors, trace elements as well as the effect of processing (mainly fermentation) were modulate...

  19. Influence of calcium chelators on concentrated micellar casein solutions : from micellar structure to viscosity and heat stability

    OpenAIRE

    Kort, de, YAW Yvonne

    2012-01-01

    In practice it is challenging to prepare a concentrated medical product with high heat stability and low viscosity. Calcium chelators are often added to dairy products to improve heat stability, but this may increase viscosity through interactions with the casein proteins. The aim of this thesis was to obtain a better understanding of the influence of different calcium chelators on the physico-chemical properties of casein micelles and the resulting effect on viscosity and heat stability of c...

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

    OpenAIRE

    Perez, J.; Jeffries, T W

    1992-01-01

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

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

  3. 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

  4. 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.

  5. Complications after procedures of photorefractive keratectomy

    Science.gov (United States)

    Gierek-Ciaciura, Stanislawa

    1998-10-01

    Purpose: The aim of this study was to investigate the saveness of the PRK procedures. Material and method: 151 eyes after PRK for correction of myopia and 112 after PRK for correction of myopic astigmatism were examined. All PRK procedures have been performed with an excimer laser manufactured by Aesculap Meditec. Results: Haze, regression, decentration infection and overcorrection were found. Conclusions: The most often complication is regression. Corneal inflammation in the early postoperative period may cause the regression or haze. The greater corrected refractive error the greater haze degree. Haze decreases with time.

  6. Influence of patient race on the outcome of photorefractive keratectomy for myopia correction Influência racial sobre os resultados da ceratectomia fotorrefrativa para a correção da miopia

    Directory of Open Access Journals (Sweden)

    Fernando Betty Cresta

    2002-03-01

    Full Text Available Purpose: To examine the effect of patient race on clinical outcomes following excimer laser surgery for myopia and myopic astigmatism. Methods: A total of 116 eyes from Caucasian patients, 16 eyes from Asian patients and 16 eyes from Hispanic patients who underwent PRK were evaluated retrospectively. PRK procedures were performed by the same surgeon using a 193 nm argon- fluoride excimer laser (VISX with 160 mJ/cm² fluence and a 6.5 Hz repetition rate at the Doheny Eye Institute. During 6 months of follow-up, changes in the uncorrected visual acuity (UCVA, refraction and spectacle-corrected visual acuity (SCVA were evaluated. Pairwise comparisons between races were performed for age, sphere and cylinder using independent sample t tests, while UCVA and SCVA were compared using Fisher's exact tests. The accepted level of significance for all tests was alpha = 0.05/3 = 0.0167. Results: The only differences found were between the Asian versus Caucasian groups related to the spectacle-corrected visual acuity of 20/15 (p=0.01 and in the Asian versus Hispanic groups related to the mean cylinder (p=0.04 at 3 months postoperatively. The comparison of the mean cylinder showed a statistically significant difference between the Asian versus Hispanic groups at 6 months postoperatively (p=0.04. After 6 months, 72.7% of the eyes in the Asian group, 85.7% of the eyes in the Hispanic group and 87.1% of the eyes in the Caucasian group had uncorrected visual acuity of 20/40 or better and the mean sphere and cylinder (±SD were: --0.55 (± 0.88 and 0.97 (± 0.79; --0.75 (± 1.24 and 0.40 (± 0.45; --1.21 (± 2.55 and 0.75 (± 0.89, respectively. Conclusion: In this study, there were no statistically significant differences between the three race groups related to the final visual outcome following photorefractive keratectomy. These preliminary results suggest that the clinical outcomes of PRK are not significantly affected by patient race. Larger populations and

  7. Iron Chelation

    Science.gov (United States)

    ... information, it does not guarantee the accuracy or currency of this information. ... makes it possible to meet patients' needs, hold impactful conferences, develop fresh education programs and fund research for the cures, along ...

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

    International Nuclear Information System (INIS)

    Highlights: ► The aim was to optimize uranium solubilization for the purposes of remediation. ► The most important factor in uranium solubilization was found to be the pH. ► Citrate treatment was the most efficient, with 63% of uranium solubilization. ► The uranium extraction yield with EDDS amendment was greater than with EDTA. - Abstract: A systematic study was made of the effects of three soil amendments on the solubilization of uranium from a granitic soil. The aim was to optimize solubilization so as to enhance bioavailability for the purposes of remediation. The three amendments tested were with citrate, EDTA, and EDDS as chelating agents. The effects of pH, chelator concentration, and leaching time were studied. The most important factor in uranium solubilization was found to be the pH. In the absence of chelating agents, the greatest solubilization was obtained for alkaline conditions, with values representing about 15% of the total uranium activity in the bulk soil. There were major differences in uranium solubilization between the different amendments. The citrate treatment was the most efficient at acidic pH, particularly with the greatest concentration of citrate tested (50 mmol kg−1) after 6 days of treatment. Under these conditions, the uranium concentration in solution was greater by a factor of 356 than in the control suspension, and represented some 63% of the uranium concentration in the bulk soil. Under alkaline conditions, the EDTA and EDDS treatments gave the greatest uranium activity concentrations in solution, but these concentrations were much lower than those with the citrate amendment, and were not very different from the control results. The uranium extraction yield with EDDS amendment was greater than with EDTA.

  9. Enhancing radium solubilization in soils by citrate, EDTA, and EDDS chelating amendments

    International Nuclear Information System (INIS)

    Highlights: ► The aim was to optimize radium solubilization for the purposes of remediation. ► The most important factor in radium solubilization was found to be the pH. ► Radium release increases with the reagent concentration. ► The largest release of radium is obtained with 50 mmol kg−1 of citrate, at pH acid, and 4 days after incubation. ► The best conditions for the release of radium are the same as for uranium. -- Abstract: The effect of three chelating agents (citrate, EDTA, and EDDS) on the solubilization of radium from a granitic soil was studied systematically, considering different soil pH values, chelating agent concentrations, and leaching times. For all the chelating agents tested, the amount of radium leached proved to be strongly dependent on the pH of the substrate: only for acidic conditions did the amount of radium released increase significantly relative to the controls. Under the best conditions, the radium released from the amended soil was greater by factors of 20 in the case of citrate, 18 for EDTA, and 14 for EDDS. The greatest improvement in the release of radium was obtained for the citrate amendment at the highest concentration tested (50 mmol kg−1). A slightly lower amount of radium was leached with EDTA at 5 mmol kg−1 soil, but the solubilization over time was very different from that observed with citrate or EDDS. With EDTA, a maximum in radium leaching was reached on the first day after amendment, while with citrate, the maximum was attained on the fourth day. With EDDS, radium leaching increased slightly but steadily with time (until the sixth day), but the net effect for the period tested was the lowest of the three reagents

  10. Evaluation of complexing properties of chelating agents for the bismuth-213

    International Nuclear Information System (INIS)

    The bismuth-213 is an alpha- and beta-emitting radioelement of very short physical half-life (45 min) obtained by means of a (225Ac-213Bi) generator. Given its radiotoxicity, this element presents an interest in radioimmunotherapy (RIT). At present, the DTPA derivatives alone are used in radiolabelling of antibodies for RIT. This study presents the complexing properties of other chelates potentially usable to this goal. Four original chelating agents were synthesized in order to choose the families giving the best results in complexing the 213Bi: the tri-ethylene-tetra-amino-hexa-carboxylic acid (HETA), the 1, 4, 7, 10-tetra-aza-cyclo-dodecane-1, 4, 7, 10-tetraacetic- 1- Gly-L-p-nitro Phe-amide (DOTA-pept), the 1, 4, 8, 11-tetrakis [(S)-2 hydroxy-propyl]-1, 4, 8, 11-tetra-aza-cyclo-tetra-decane (THEOH), and the ethylenediamine di-acetate di-acetamide-bis-thiophenol (EDTA-TH). Given the physical characteristics of 213Bi and the goal of our research, the studies of complexation were conducted by C.C.M. on silica, in highly diluted solution, with fixed chelates-213Bi incubation time (15 min), and variable temperature and concentrations. Analysis of the results have been done by means of a phosphor-imager by measuring the number of pixels associated to every chromatographic spot. The obtained results show that the poly-aza poly-carboxylic derivatives and poly-aza di-thio dicarboxylic derivatives are the only able ones to complex rapidly and quantitatively the 213Bi

  11. Metal distribution and spectroscopic analysis after soil washing with chelating agents and humic substances.

    Science.gov (United States)

    Tsang, Daniel C W; Hartley, Neil R

    2014-03-01

    Biodegradable chelating agents ([S,S]-ethylenediamine-N,N-disuccinic acid (EDDS) and glutamic-N,N-diacetic acid (GLDA)) and natural humic substances (lignite-derived, standard, and commercially available humic acids) are potentially useful for enhancing soil remediation of timber treatment sites. This study integrated macroscopic and spectroscopic analyses to assess their influence on the distribution and chemical speciation of the remaining metals as well as their interaction with the soil surface after 48-h washing of a field-contaminated soil. The results demonstrated that EDDS and GLDA were an appealing alternative to non-biodegradable ethylenediamine-tetraacetic acid, but the three humic substances were less effective. As shown by sequential extractions, Cu was primarily extracted from the carbonate fraction while Cr and As extraction resulted from (co-)dissolution of the oxide fraction. As a result, the relative proportion of strongly bound organic matter and residual fractions increased by 7-16 %. However, it was noteworthy that the exchangeable fraction also increased by 5-11 %, signifying that a portion of the remaining metals was destabilized by chelating agents and transformed to be more labile in the treated soil. The X-ray photoelectron spectroscopy spectra confirmed the substantial removal of readily accessible Cu from the soil surface, but Cr maintained its original chemical forms of trivalent chromium oxides and iron-chromium coprecipitates, whereas As remained as arsenic trioxide/pentoxide and copper arsenate precipitates. On the other hand, the absence of characteristic peaks of adsorbed carboxylate groups in the Fourier-transform infrared (FTIR) spectra inferred that the extent of adsorption of chelating agents and humic substances on the bulk soil was insufficient to be characterized by FTIR analysis. These results suggested that attention should be paid to the exchangeable fraction of Cu and oxides/coprecipitates of As prior to possible on

  12. Studies of inclusion complexes between cyclodextrins and polyazamacrocyclic chelates of lanthanide (III) ions

    International Nuclear Information System (INIS)

    The complexes between γ-cyclodextrin and lanthanide (III) chelates of the polyazamacrocycles DOTA (DOTA ≡ 1,4,7,10-tertraazacyclododecane-1,4,7,10-tetraacetate) and DOTP (DOTP ≡ 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetramethylenephosphonate) have been thought out to enhance the potential of such chelates as contrast agents for MRI. Given the actual demand for the design of new contrast agents, we thought it worthwhile to confirm previous results for the equilibrium constant K obtained by one of us by NMR on the DOTP complex, as well as to determine K for a new one with DOTA. Further, we wanted to study and quantify the interactions present in these complexes, with a view to improve them in newly designed complexes. The interactions between γ-cyclodextrin and the lanthanide (III)-polyazamacrocyclic chelates, [Tm(DOTP)]5-, and [Gd(DOTA)]- were then studied by isothermal calorimetry (ITC) and molecular dynamics. The calorimetric experiments can be interpreted by considering that in both cases there is a weak association, characterized by low values for the equilibrium constant as well as for the molar enthalpy change for complex formation, at T=298.15 K. The K value for the complex with DOTP obtained now by ITC is of the same order of magnitude of the one determined previously by NMR. Further, the complex formation seems rather insensitive to the macrocycle, as the values now obtained by ITC for the DOTA complex are very similar to the ones obtained for the DOTP complex. We have also carried out molecular dynamics simulations on these very same inclusion complexes, which provided quantitative data on the interactions present, as well as a plausible explanation for the data obtained, leading to the proposal of possible solutions to improve the modelling of new contrast agents on a host-guest basis

  13. Degradation of toluene, ethylbenzene, and xylene using heat and chelated-ferrous iron activated persulfate oxidation

    Science.gov (United States)

    Mondal, P.; Sleep, B.

    2014-12-01

    Toluene, ethylbenze, and xylene (TEX) are common contaminants in the subsurface. Activated persulfate has shown promise for degrading a wide variety of organic compounds. However, studies of persulfate application for in situ degradation of TEX and effects on the subsequent bioremediation are limited. In this work, degradation studies of TEX in aqueous media and soil are being conducted using heat activated and chelated-ferrous iron activated persulfate oxidation in batch and flow-through column experiments. In the batch experiments, sodium persulfate is being used at different concentrations to provide an initial persulfate to TEX molar ratios between 10:1 and 100:1. Sodium persulfate solutions are being activated at 20, 37, 60, and 80 oC temperatures for the heat activated oxidation. For the chelated-ferrous iron activated oxidation, ferrous iron and citric acid, both are being used at concentration of 5 mM. In the experiments with soil slurry, a soil to water ratio of 1 to 5 is being used. Flow through water saturated column experiments are being conducted with glass columns (45 cm in length and 4 cm in diameter) uniformly packed with soils, and equilibrated with water containing TEX at the target concentrations. Both the heat activation and chelated-ferrous iron activation of persulfate are being employed in the column experiments. Future experiments are planned to determine the suitability of persulfate oxidation of TEX on the subsequent biodegradation using batch microcosms containing TEX degrading microbial cultures. In these experiments, the microbial biomass will be monitored using total phospholipids, and the microbial community will be determined using quantitative real-time polymerase chain reaction (qPCR) on the extracted DNA. This study is expected to provide suitable operating conditions for in situ chemical oxidation of TEX with activated persulfate followed by bioremediation.

  14. Colour and stability assessment of blue ferric anthocyanin chelates in liquid pectin-stabilised model systems.

    Science.gov (United States)

    Buchweitz, M; Brauch, J; Carle, R; Kammerer, D R

    2013-06-01

    The formation of blue coloured ferric anthocyanin chelates and their colour stability during storage and thermal treatment were monitored in a pH range relevant to food (3.6-5.0). Liquid model systems were composed of different types of Citrus pectins, juices (J) and the respective phenolic extracts (E) from elderberry (EB), black currant (BC), red cabbage (RC) and purple carrot (PC) in the presence of ferric ions. For EB, BC and PC, pure blue colours devoid of a violet tint were exclusively observed for the phenolic extracts and at pH values ≥ 4.5 in model systems containing high methoxylated and amidated pectins, respectively. Colour and its stability strongly depended on the amount of ferric ions and the plant source; however, colour decay could generally be described as a pseudo-first-order kinetics. Despite optimal colour hues for RC-E and RC-J, storage and heat stabilities were poor. Highest colour intensities and best stabilities were observed for model systems containing PC-E at a molar anthocyanin:ferric ion ratio of 1:2. Ascorbic and lactic acids interfered with ferric ions, thus significantly affecting blue colour evolution and stability. Colour loss strongly depended on heat exposure with activation energies ranging between 60.5 and 78.4 kJ/mol. The comprehensive evaluation of the interrelationship of pigment source, pH conditions and pectin type on chelate formation and stability demonstrated that ferric anthocyanin chelates are promising natural blue food colourants. PMID:23411339

  15. 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. PMID:26423283

  16. Solubility and accumulation of metals in Chinese brake fern, vetiver and rostrate sesbania using chelating agents.

    Science.gov (United States)

    Lou, L Q; Ye, Z H; Wong, M H

    2007-01-01

    Greenhouse experiments were conducted to study the effects of chelating agents on the growth and metal accumulation of Chinese brake fern (Pteris vittata L.), vetiver (Vetiveria zizanioides L.), and rostrate sesbania (Sesbania rostrata L.) in soil contaminated with arsenic (As), Cu, Pb, and Zn. Among the five chelating agents used [ethylenediaminetriacetic acid (EDTA), hydroxyethylenediaminetriacetic acid (HEDTA), nitrilotriacetic acid (NTA), oxalic acid (OA), and phytic acid (PA)], OA was the best to mobilize As, EDTA to mobilize Cu and Pb, and HEDTA to mobilize Zn from soil, respectively. The biomass of vetiver was the highest, followed by rostrate sesbania. All chelating agents inhibited the growth of Chinese brake fern and rostrate sesbania, but HEDTA significantly increased the aboveground biomass of vetiver. Dry weights of both Chinese brake fern and rostrate sesbania decreased with increasing EDTA concentrations amended in the soil, especially in treatments with high EDTA concentrations. EDTA and HEDTA enhanced Cu, Zn, and Pb, but lowered As accumulation in all three plant species, except for As in vetiver, while OA significantly enhanced As accumulation in the aboveground part of vetiver. Concentrations of Cu, Zn, and Pb in the aboveground parts of plants increased significantly with the increase of EDTA concentrations and treatment time. In addition to As, Chinese brake fern also accumulated the highest Cu, Pb, and Zn in its aboveground parts among the three plant species grown in metal-contaminated soil with EDTA/HEDTA treatments. This species, therefore, can be used to simultaneously clean up As, Cu, Pb, and Zn from contaminated soils with the aid of EDTA or HEDTA. PMID:18246709

  17. D-Penicillamine tripodal derivatives as efficient copper(I) chelators.

    Science.gov (United States)

    Jullien, Anne-Solène; Gateau, Christelle; Lebrun, Colette; Kieffer, Isabelle; Testemale, Denis; Delangle, Pascale

    2014-05-19

    New tripodal metal-chelating agents derived from nitrilotriacetic acid (NTA) and extended by three unnatural amino acids D-penicillamine (D-Pen) are presented. D-Pen is actually the drug most extensively used to treat copper (Cu) overload in Wilson's disease and as such is a very attractive building block for the design of chelating agents. D-Pen is also a bulkier analogue of cysteine, with the β-methylene hydrogen atoms replaced by larger methyl groups. The hindrance of the gem-dimethyl group close to the thiol functions is demonstrated to influence the speciation and stability of the metal complexes. The ligands L(4) (ester) and L(5) (amide) were obtained from NTA and commercial D-Pen synthons in four and five steps with overall yields of 14 and 24%, respectively. Their ability to bind Cu(I), thanks to their three thiolate functions, has been investigated using both spectroscopic and analytical methods. UV, CD, and NMR spectroscopy and mass spectrometry evidence the formation of two Cu(I) complexes with L(5): the mononuclear complex CuL(5) and one cluster (Cu2L(5))2. In contrast, the bulkier ethyl ester derivative L(4) cannot accommodate the mononuclear complex in solution and thus forms exclusively the cluster (Cu2L(4))2. Cu K-edge X-ray absorption spectroscopy (XAS and EXAFS) confirms that Cu(I) is bound in trigonal-planar sulfur-only environments in all of these complexes with Cu- - -S distances ranging from 2.22 to 2.23 Å. Such C3-symmetric CuS3 cores are coordination modes frequently adopted in Cu(I) proteins such as metallothioneins. These two ligands bind Cu(I) tightly and selectively, which makes them promising chelators for intracellular copper detoxification in vivo. PMID:24766067

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

    Energy Technology Data Exchange (ETDEWEB)

    Lozano, J.C. [Departamento de Fisica Fundamental, Universidad de Salamanca, 37008 Salamanca (Spain); Blanco Rodriguez, P. [Natural Radioactivity Group, Universidad de Extremadura, Avda. Elvas s/n, 06071 Badajoz (Spain); Vera Tome, F., E-mail: fvt@unex.es [Natural Radioactivity Group, Universidad de Extremadura, Avda. Elvas s/n, 06071 Badajoz (Spain); Calvo, C. Prieto [Departamento de Fisica Fundamental, Universidad de Salamanca, 37008 Salamanca (Spain)

    2011-12-30

    Highlights: Black-Right-Pointing-Pointer The aim was to optimize uranium solubilization for the purposes of remediation. Black-Right-Pointing-Pointer The most important factor in uranium solubilization was found to be the pH. Black-Right-Pointing-Pointer Citrate treatment was the most efficient, with 63% of uranium solubilization. Black-Right-Pointing-Pointer The uranium extraction yield with EDDS amendment was greater than with EDTA. - Abstract: A systematic study was made of the effects of three soil amendments on the solubilization of uranium from a granitic soil. The aim was to optimize solubilization so as to enhance bioavailability for the purposes of remediation. The three amendments tested were with citrate, EDTA, and EDDS as chelating agents. The effects of pH, chelator concentration, and leaching time were studied. The most important factor in uranium solubilization was found to be the pH. In the absence of chelating agents, the greatest solubilization was obtained for alkaline conditions, with values representing about 15% of the total uranium activity in the bulk soil. There were major differences in uranium solubilization between the different amendments. The citrate treatment was the most efficient at acidic pH, particularly with the greatest concentration of citrate tested (50 mmol kg{sup -1}) after 6 days of treatment. Under these conditions, the uranium concentration in solution was greater by a factor of 356 than in the control suspension, and represented some 63% of the uranium concentration in the bulk soil. Under alkaline conditions, the EDTA and EDDS treatments gave the greatest uranium activity concentrations in solution, but these concentrations were much lower than those with the citrate amendment, and were not very different from the control results. The uranium extraction yield with EDDS amendment was greater than with EDTA.

  19. Enhancing radium solubilization in soils by citrate, EDTA, and EDDS chelating amendments

    Energy Technology Data Exchange (ETDEWEB)

    Prieto, C.; Lozano, J.C. [Departamento de Física Fundamental, Universidad de Salamanca, 37008 Salamanca (Spain); Rodríguez, P. Blanco [Natural Radioactivity Group, Universidad de Extremadura, Avda. Elvas s/n, 06071 Badajoz (Spain); Tomé, F. Vera, E-mail: fvt@unex.es [Natural Radioactivity Group, Universidad de Extremadura, Avda. Elvas s/n, 06071 Badajoz (Spain)

    2013-04-15

    Highlights: ► The aim was to optimize radium solubilization for the purposes of remediation. ► The most important factor in radium solubilization was found to be the pH. ► Radium release increases with the reagent concentration. ► The largest release of radium is obtained with 50 mmol kg{sup −1} of citrate, at pH acid, and 4 days after incubation. ► The best conditions for the release of radium are the same as for uranium. -- Abstract: The effect of three chelating agents (citrate, EDTA, and EDDS) on the solubilization of radium from a granitic soil was studied systematically, considering different soil pH values, chelating agent concentrations, and leaching times. For all the chelating agents tested, the amount of radium leached proved to be strongly dependent on the pH of the substrate: only for acidic conditions did the amount of radium released increase significantly relative to the controls. Under the best conditions, the radium released from the amended soil was greater by factors of 20 in the case of citrate, 18 for EDTA, and 14 for EDDS. The greatest improvement in the release of radium was obtained for the citrate amendment at the highest concentration tested (50 mmol kg{sup −1}). A slightly lower amount of radium was leached with EDTA at 5 mmol kg{sup −1} soil, but the solubilization over time was very different from that observed with citrate or EDDS. With EDTA, a maximum in radium leaching was reached on the first day after amendment, while with citrate, the maximum was attained on the fourth day. With EDDS, radium leaching increased slightly but steadily with time (until the sixth day), but the net effect for the period tested was the lowest of the three reagents.

  20. Adsorption characteristics of Ni(II) onto MA-DTPA/PVDF chelating membrane

    International Nuclear Information System (INIS)

    The melamine-diethylenetriaminepentaacetic acid/polyvinylidene fluoride (MA-DTPA/PVDF) chelating membrane bearing polyaminecarboxylate groups was prepared for the removal of Ni(II) from wastewater effluents. The membrane was characterized by SEM, 13C NMR and FTIR techniques. Quantitative adsorption experiments were performed in view of pH, contact time, temperature, the presence of Ca(II) and lactic acid as the controlling parameters. Adsorption kinetics and equilibrium were examined regarding the single Ni(II) system, binary Ni(II) and Ca(II) system and nickel-lactic acid complexes system. The desorption efficiency was also evaluated, and the adsorption mechanism was suggested based on experimental data. The results show that the sorption kinetics fit well to Lagergren second-order equation and the isotherms can be well described by Langmuir model. At 298 K, the second-order rate constant is calculated to be 4.171, 11.39, 6.203 cm2/(mg min) and the equilibrium uptake is 0.0264, 0.0211 and 0.0216 mg/cm2 in the aforementioned three systems. The distribution coefficient of Ni(II) slowly decreases from 4.27 to 2.72, and the separation factor (fNi(II)/Ca(II)) increases from 3.10 to 8.46 when the initial Ca(II) concentration varies from 20 to 200 mg/L. This reveals the chelating membrane shows more affinity for Ni(II) than Ca(II) ions. In the studied range of lactic acid concentration, Ni(II) uptake decreases with the maximum ratio of 10%. Chemical bonding (chelation) dominates in the adsorption process, and the negative ΔGo and ΔHo indicate the spontaneous and exothermic nature of adsorption.