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Sample records for 64cucu-bisthiosemicarbazone radiopharmaceutical binding

  1. Melanin-binding radiopharmaceuticals

    SciTech Connect

    Packer, S; Fairchild, R G; Watts, K P; Greenberg, D; Hannon, S J

    1980-01-01

    The scope of this paper is limited to an analysis of the factors that are important to the relationship of radiopharmaceuticals to melanin. While the authors do not attempt to deal with differences between melanin-binding vs. melanoma-binding, a notable variance is assumed. (PSB)

  2. Radiopharmaceuticals

    SciTech Connect

    Theobald, A.E.

    1989-01-01

    This book is a review of the latest developments in radiopharmaceuticals. It covers the development of radiopharmaceutical compounds, the theory and practice of their synthesis, and examples of their application. Also covers safe handling of radiopharmaceuticals, legislation affecting their use, radiation monitoring, radiochromatography, and computer techniques.

  3. Species Dependence of [64Cu]Cu-Bis(thiosemicarbazone) Radiopharmaceutical Binding to Serum Albumins

    PubMed Central

    Basken, Nathan E.; Mathias, Carla J.; Lipka, Alexander E.; Green, Mark A.

    2008-01-01

    Introduction Interactions of three copper(II) bis(thiosemicarbazone) PET radiopharmaceuticals with human serum albumin, and the serum albumins of four additional mammalian species, were evaluated. Methods 64Cu-labeled diacetyl bis(N4-methylthiosemicarbazonato)copper(II) (Cu-ATSM), pyruvaldehyde bis(N4-methylthiosemicarbazonato)copper(II) (Cu-PTSM), and ethylglyoxal bis(thiosemicarbazonato)copper(II) (Cu-ETS) were synthesized and their binding to human, canine, rat, baboon, and porcine serum albumins quantified by ultrafiltration. Protein binding was also measured for each tracer in human, porcine, rat, and mouse serum. Results The interaction of these neutral, lipophilic copper chelates with serum albumin is highly compound- and species-dependent. Cu-PTSM and Cu-ATSM exhibit particularly high affinity for human serum albumin (HSA), while the albumin binding of Cu-ETS is relatively insensitive to species. At HSA concentrations of 40 mg/mL, “% Free” (non-albumin-bound) levels of radiopharmaceutical were 4.0 ± 0.1%; 5.3 ± 0.2%; and 38.6 ± 0.8% for Cu-PTSM; Cu-ATSM; and Cu-ETS, respectively. Conclusions Species-dependent variations in radiopharmaceutical binding to serum albumin may need to be considered when using animal models to predict the distribution and kinetics of these compounds in humans. PMID:18355683

  4. Estrogen receptor binding radiopharmaceuticals: II. Tissue distribution of 17. cap alpha. -methylestradiol in normal and tumor-bearing rats

    SciTech Connect

    Feenstra, A.; Vaalburg, W.; Nolten, G.M.J.; Reiffers, S.; Talma, A.G.; Wiegman, T.; van der Molen, H.D.; Woldring, M.G.

    1983-06-01

    Tritiated 17..cap alpha..-methylestradiol was synthesized to investigate the potential of the carbon-11-labeled analog as an estrogen-receptor-binding radiopharmaceutical. In vitro, 17..cap alpha..-methylestradiol is bound with high affinity to the cytoplasmic estrogen receptor from rabbit uterus (K/sub d/ = 1.96 x 10/sup -10/M), and it sediments as an 8S hormone-receptor complex in sucrose gradients. The compound shows specific uptake in the uterus of the adult rat, within 1 h after injection. In female rats bearing DMBA-induced tumors, specific uterine and tumor uptakes were observed, although at 30 min the tumor uptake was only 23 to 30% of the uptake in the uterus. Tritiated 17..cap alpha..-methylestradiol with a specific activity of 6 Ci/mmole showed a similar tissue distribution. Our results indicate that a 17 ..cap alpha..-methylestradiol is promising as an estrogen-receptor-binding radiopharmaceutical.

  5. In vivo binding in rat brain and radiopharmaceutical preparation of radioiodinated HEAT, an alpha-1 adrenoceptor ligand

    SciTech Connect

    Couch, M.W.; Greer, D.M.; Thonoor, C.M.; Williams, C.M.

    1988-03-01

    In vivo binding of (/sup 125/I)-2-(beta-(3-iodo-4-hydroxyphenyl)ethylaminomethyl tetralone) ((/sup 125/I)HEAT) to alpha-1 adrenoceptors in the rat brain was determined over 4 hr. Uptake in the thalamus and frontal cortex was approximately 0.1% injected dose per gram tissue. Thalamus/cerebellum ratios of 10:1 and frontal cortex/cerebellum ratios of 5:1 were found at 4 hr. Pretreatment with prazosin, an alpha-1 antagonist, completely inhibited the accumulation of (/sup 125/I)HEAT in thalamus and frontal cortex; yet uptake of radioactivity was not significantly affected by antagonists and agonists for other receptors classes (propranolol, beta-1; apomorphine, D-1; spiperone, D-2). Binding of (/sup 125/I)HEAT is saturable. At 4 hr, (/sup 125/I)HEAT or (/sup 123/I)HEAT was shown to be the only radioactive material in rat thalamus and frontal cortex. Iodine-123 HEAT and (/sup 125/I)HEAT were synthesized as radiopharmaceuticals within 3 hr in 99% radiochemical purity.

  6. Kinetic sensitivity of a receptor-binding radiopharmaceutical: Technetium-99m galactosyl-neoglycoalbumin

    SciTech Connect

    Vera, D.R.; Woodle, E.S.; Stadalnik, R.C. )

    1989-09-01

    Kinetic sensitivity is the ability of a physiochemical parameter to alter the time-activity curve of a radiotracer. The kinetic sensitivity of liver and blood time-activity data resulting from a single bolus injection of ({sup 99m}Tc)galactosyl-neoglycoalbumin (( Tc)NGA) into healthy pigs was examined. Three parameters, hepatic plasma flow scaled as flow per plasma volume, ligand-receptor affinity, and total receptor concentration, were tested using (Tc)NGA injections of various molar doses and affinities. Simultaneous measurements of plasma volume (iodine-125 human serum albumin dilution), and hepatic plasma flow (indocyanine green extraction) were performed during 12 (Tc)NGA studies. Paired data sets demonstrated differences (P(chi v2) less than 0.01) in liver and blood time-activity curves in response to changes in each of the tested parameters. We conclude that the (Tc)NGA radiopharmacokinetic system is therefore sensitive to hepatic plasma flow, ligand-receptor affinity, and receptor concentration. In vivo demonstration of kinetic sensitivity permits delineation of the physiologic parameters that determine the biodistribution of a radiopharmaceutical. This delineation is a prerequisite to a valid analytic assessment of receptor biochemistry via kinetic modeling.

  7. Cu(II) Bis(thiosemicarbazone) Radiopharmaceutical Binding to Serum Albumin: Further Definition of Species-Dependence and Associated Substituent Effects

    PubMed Central

    Basken, Nathan E.; Green, Mark A.

    2009-01-01

    Introduction The Cu-PTSM (pyruvaldehyde bis(N4-methylthiosemicarbazonato)copper(II)) and Cu-ATSM (diacetyl bis(N4-methylthiosemicarbazonato)copper(II)) radiopharmaceuticals exhibit strong, species-dependent binding to the IIA site of human serum albumin (HSA), while the related Cu-ETS (ethylglyoxal bis(thiosemicarbazonato)copper(II)) radiopharmaceutical appears to only exhibit non-specific binding to human and animal serum albumins. Methods To further probe the structural basis for the species-dependence of this albumin binding interaction, protein binding of these three radiopharmaceuticals was examined in solutions of albumin and/or serum from a broader array of mammalian species (rat, sheep, donkey, rabbit, cow, pig, dog, baboon, mouse, cat, elephant). We also evaluated the albumin binding of several copper(II) bis(thiosemicarbazone) chelates offering more diverse substitution of the ligand backbone. Results Cu-PTSM and Cu-ATSM exhibit a strong interaction with HSA that is not apparent with the albumins of other species, while the binding of Cu-ETS to albumin is much less species-dependent. The strong interaction of Cu-PTSM with HSA does not appear to simply correlate with variation, relative to the animal albumins, of a single amino acid lining HSA's IIA site. Those agents that selectively interact with HSA share the common feature of only methyl or hydrogen substitution at the carbon atoms of the diimine fragment of the ligand backbone. Conclusions The interspecies variations in albumin binding of Cu-PTSM and Cu-ATSM are not simply explained by unique amino acid substitutions in the IIA binding pocket of the serum albumins. However, the specific affinity for this region of HSA is disrupted when substituents bulkier than a methyl group appear on the imine carbons of the copper bis(thiosemicarbazone) chelate. PMID:19520290

  8. Binding of ReO4(-) with an engineered MoO4(2-)-binding protein: towards a new approach in radiopharmaceutical applications.

    PubMed

    Aryal, Baikuntha P; Brugarolas, Pedro; He, Chuan

    2012-01-01

    Radiolabeled biomolecules are routinely used for clinical diagnostics. (99m)Tc is the most commonly used radioactive tracer in radiopharmaceuticals. (188)Re and (186)Re are also commonly used as radioactive tracers in medicine. However, currently available methods for radiolabeling are lengthy and involve several steps in bioconjugation processes. In this work we present a strategy to engineer proteins that may selectively recognize the perrhenate (ReO(4)(-)) ion as a new way to label proteins. We found that a molybdate (MoO(4)(2-))-binding protein (ModA) from Escherichia coli can bind perrhenate with high affinity. Using fluorescence and isothermal titration calorimetry measurements, we determined the dissociation constant of ModA for ReO(4)(-) to be 541 nM and we solved a crystal structure of ModA with a bound ReO(4)(-). On the basis of the structure we created a mutant protein containing a disulfide linkage, which exhibited increased affinity for perrhenate (K(d) = 104 nM). High-resolution crystal structures of ModA (1.7 Å) and A11C/R153C mutant (2.0 Å) were solved with bound perrhenate. Both structures show that a perrhenate ion occupies the molybdate binding site using the same amino acid residues that are involved in molybdate binding. The overall structure of the perrhenate-bound ModA is unchanged compared with that of the molybdate-bound form. In the mutant protein, the bound perrhenate is further stabilized by the engineered disulfide bond. PMID:21861186

  9. 'Naked' radiopharmaceuticals

    SciTech Connect

    Wallner, Paul E. . E-mail: pwallner@rtsx.com

    2006-10-01

    The term 'naked' radiopharmaceuticals, more appropriately, 'unbound' radiopharmaceuticals, refers to any radioisotope used for clinical research or clinical purposes that is not attached to a chemical or biological carrier, and that localizes in various tissues because of a physiologic or chemical propensity/affinity, or secondary to focal anatomic placement. Although they remain useful in selected clinical circumstances, the available agents (except for Iodine-131) have been relegated to an unfortunate and somewhat secondary role. The agents remain useful and worthy of consideration for new clinical investigation and clinical use.

  10. Radiopharmaceuticals for thrombus detection

    SciTech Connect

    Knight, L.C. )

    1990-01-01

    Most of the components of the thrombotic and fibrinolytic systems have at some time been evaluated as a means of carrying a radiolabel specifically to thrombi, although very few have been promising enough to emerge from investigational status to routine clinical use. New approaches are being explored, including improved methods of labeling platelets, chemically modified forms of previously tested plasma proteins, and new biomolecules, including monoclonal antibodies specific for fibrin and platelets. The current goal is to find one or more radiotracers that bind specifically and rapidly to thrombi, and that also have a rapid blood disappearance rate, permitting a clear diagnosis within a few hours after injection. Because this test may be needed to assess the course of therapy in an anticoagulated patient, the ideal radiopharmaceutical should be able to locate thrombi without interference by anticoagulants. Until a suitable thrombus-specific radiopharmaceutical becomes generally available, many hospitals will continue to attempt to make a diagnosis with nonspecific radiopharmaceuticals that can at best provide blood pool images to indicate filling defects. Several of the new approaches seem likely to provide the radiopharmaceutical sought, although clinical trials are at an early stage.137 references.

  11. Agonist and antagonist bind differently to 5-HT1A receptors during Alzheimer's disease: A post-mortem study with PET radiopharmaceuticals.

    PubMed

    Vidal, Benjamin; Sebti, Johan; Verdurand, Mathieu; Fieux, Sylvain; Billard, Thierry; Streichenberger, Nathalie; Troakes, Claire; Newman-Tancredi, Adrian; Zimmer, Luc

    2016-10-01

    PET imaging studies using 5-HT1A receptor radiotracers show a decreased density of this receptor in hippocampi of patients with Alzheimer's disease (AD) at advanced stages. However, current 5-HT1A receptor radiopharmaceuticals used in neuroimaging are antagonists, thought to bind to 5-HT1A receptors in different functional states (i.e., both the one which displays high affinity for agonists and is thought to mediate receptor activation, as well as the state which has low affinity for agonists). Comparing the PET imaging obtained using an agonist radiotracer, which binds selectively to functional receptors, with the PET imaging obtained using an antagonist radiotracer would therefore provide original information on 5-HT1A receptor impairment during AD. Quantitative autoradiography using [(18)F]F13640 and [(18)F]MPPF, a 5-HT1A agonist and antagonist, respectively, was measured in hippocampi of patients with AD (n = 25, at different Braak stages) and control subjects (n = 9). The neuronal density was measured in the same tissues by NeuN immunohistochemistry. The specific binding of both radiotracers was determined by addition of WAY-100635, a selective 5-HT1A receptor antagonist. The autoradiography distribution of both 5-HT1A PET radiotracers varied across hippocampus regions. The highest binding density was in the pyramidal layer of CA1. Incubation with Gpp(NH)p, a non-hydrolysable analogue of GTP, reduced significantly [(18)F]F13640 binding in hippocampal regions, confirming its preferential interaction with G-coupled receptors, and slightly increased [(18)F]MPPF binding. In the CA1 subfield, [(18)F]F13640 binding was significantly decreased at Braak stages I/II (-19%), Braak stages III/IV (-23%), and Braak stages V/VI (-36%) versus control. In contrast, [(18)F]MPPF binding was statistically reduced only at the most advanced Braak stages V/VI compared to control (-33%). Since [(18)F]F13640 and [(18)F]MPPF can be used in vivo in humans, this

  12. Organometallic Radiopharmaceuticals

    NASA Astrophysics Data System (ADS)

    Alberto, Roger

    Although molecular imaging agents have to be synthesized ultimately from aqueous solutions, organometallic complexes are becoming more and more important as flexible yet kinetically stable building blocks for radiopharmaceutical drug discovery. The diversity of ligands, targets, and targeting molecules related to these complexes is an essential base for finding novel, noninvasive imaging agents to diagnose and eventually treat widespread diseases such as cancer. This review article covers the most important findings toward these objectives accomplished during the past 3-4 years. The two major available organometallic building blocks will be discussed in the beginning together with constraints for market introduction as imposed by science and industry. Since targeting radiopharmaceuticals are a major focus of current research in molecular imaging, attempts toward so-called technetium essential radiopharmaceuticals will be briefly touched in the beginning followed by the main discussion about the labeling of targeting molecules such as folic acid, nucleosides, vitamins, carbohydrates, and fatty acids. At the end, some new strategies for drug discovery will be introduced together with results from organometallic chemistry in water. The majority of the new results have been achieved with the [99mTc(OH2)3(CO)3]+ complex which will, though not exclusively, be a focus of this review.

  13. Radiopharmaceuticals for diagnosis and treatment

    SciTech Connect

    Kuhl, D.E.

    1992-01-01

    We report on our efforts in PET basic radiochemistry, radiopharmaceutical synthesis, and preclinical radiopharmaceutical evaluation. These efforts are focused on three fronts. First predictive abilities in nucleophilic aromatic substitution with [[sup 18]F]fluorination of substituted aromatic rings. Although radiochemical yields can be predicted within a very similar group of compounds with similar leaving groups and substituent patterns, generalization to all nucleophilic substitutions with [[sup 18]F] fluoride is not warranted. Kinetic studies indicate significantly different rates of reactions, depending on ring substituents. Second, preclinical evaluation of new radiopharmaceuticals. We have synthesized and begun the preclinical evaluation of [[sup 11]C]tetrabenazine, a new radioligand based on the vesicular monoamine transport system. Third, our work, on [[sup 18]F]fluorination/decarbonylation reactions, structure-activity relationships in dopamine uptake inhibitors and effects of chronic drugs on radioligand binding is described.

  14. γ-Tilmanocept, a New Radiopharmaceutical Tracer for Cancer Sentinel Lymph Nodes, Binds to the Mannose Receptor (CD206)

    PubMed Central

    Azad, Abul K.; Rajaram, Murugesan V. S.; Metz, Wendy L.; Cope, Frederick O.; Blue, Michael S.; Vera, David R.

    2015-01-01

    γ-Tilmanocept (99mTc-labeled-tilmanocept or [99mTc]-tilmanocept) is the first mannose-containing, receptor-directed, radiolabeled tracer for the highly sensitive imaging of sentinel lymph nodes in solid tumor staging. To elucidate the mannose-binding receptor that retains tilmanocept in this microenvironment, human macrophages were used that have high expression of the C-type lectin mannose receptor (MR; CD206). Cy3-labeled tilmanocept exhibited high specificity binding to macrophages that was nearly abolished in competitive inhibition experiments. Furthermore, Cy3-tilmanocept binding was markedly reduced on macrophages deficient in the MR by small interfering RNA treatment and was increased on MR-transfected HEK 293 cells. Finally, confocal microscopy revealed colocalization of Cy3-tilmanocept with the macrophage membrane MR and binding of labeled tilmanocept to MR+ cells (macrophages and/or dendritic cells) in human sentinel lymph node tissues. Together these data provide strong evidence that CD206 is a major binding receptor for γ-tilmanocept. Identification of CD206 as the γ-tilmanocept–binding receptor enables opportunities for designing receptor-targeted advanced imaging agents and therapeutics for cancer and other diseases. PMID:26202986

  15. Medicinal Radiopharmaceutical Chemistry of Metal Radiopharmaceuticals

    NASA Astrophysics Data System (ADS)

    Saw, Maung Maung

    2012-06-01

    Metal complexes have been used as medicinal compounds. Metals have advantageous features over organic compounds. Significant applications of metal complexes are in the field of nuclear medicine. Radiopharmaceuticals are drugs containing radioisotopes used for diagnostic and therapeutic purposes. The generalized targeting strategy for molecular imaging probe consists of three essential parts: (i) reporter unit or payload, (ii) carrier, and (iii) targeting system. Medicinal radiopharmaceutical chemistry pays special consideration to radioisotopes, as a reporter unit for diagnostic application or as a payload for therapeutic application. Targeting is achieved by a few approaches but the most common is the bifunctional chelator approach. While designing a radiopharmaceutical, a range of issues needs to be considered including properties of metal radioisotopes, bifunctional chelators, linkers, and targeting molecules. Designing radiopharmaceuticals requires consideration of two key words: "compounds of biological interest" and "fit for intended use." The ultimate goal is the development of new diagnostic methods and treatment. Diagnostic metal radiopharmaceuticals are used for SPECT and PET applications. Technetium chemistry constitutes a major portion of SPECT and gallium chemistry constitutes a major portion of PET. Therapeutic radiopharmaceuticals can be constructed by using alpha-, beta minus-, or Auger electron-emitting radiometals. Special uses of medicinal radiopharmaceuticals include internal radiation therapy, brachytherapy, immunoPET, radioimmunotherapy, and peptide receptor radionuclide imaging and therapy.

  16. Binding of ReO[subscript 4];#8722; with an engineered MoO[subscript 4 superscript 2];#8722;-binding protein: towards a new approach in radiopharmaceutical applications

    SciTech Connect

    Aryal, Baikuntha P.; Brugarolas, Pedro; He, Chuan

    2012-05-25

    Radiolabeled biomolecules are routinely used for clinical diagnostics. {sup 99m}Tc is the most commonly used radioactive tracer in radiopharmaceuticals. {sup 188}Re and {sup 186}Re are also commonly used as radioactive tracers in medicine. However, currently available methods for radiolabeling are lengthy and involve several steps in bioconjugation processes. In this work we present a strategy to engineer proteins that may selectively recognize the perrhenate (ReO{sub 4}{sup -}) ion as a new way to label proteins. We found that a molybdate (MoO{sub 4}{sup 2-})-binding protein (ModA) from Escherichia coli can bind perrhenate with high affinity. Using fluorescence and isothermal titration calorimetry measurements, we determined the dissociation constant of ModA for ReO{sub 4}{sup -} to be 541 nM and we solved a crystal structure of ModA with a bound ReO{sub 4}{sup -}. On the basis of the structure we created a mutant protein containing a disulfide linkage, which exhibited increased affinity for perrhenate (K{sub d} = 104 nM). High-resolution crystal structures of ModA (1.7 {angstrom}) and A11C/R153C mutant (2.0 {angstrom}) were solved with bound perrhenate. Both structures show that a perrhenate ion occupies the molybdate binding site using the same amino acid residues that are involved in molybdate binding. The overall structure of the perrhenate-bound ModA is unchanged compared with that of the molybdate-bound form. In the mutant protein, the bound perrhenate is further stabilized by the engineered disulfide bond.

  17. Radiopharmaceuticals for diagnosis and treatment

    SciTech Connect

    Kuhl, D.E.

    1991-01-01

    In this grant period we have continued our efforts in the areas of PE basic radiochemistry, radiopharmaceutical synthesis, and preclinical radiopharmaceutical evaluation. A new synthetic sequence, consisting, of no-carrier-added fluorine-18 labeling of substituted benzaldehydes followed by reductive decarbonylation, has been developed. This new methodology can be applied to the fluorine-18 labeling of a wide variety of drugs not previously accessible through existing fluorine-18 labeling methods. Following up on a literature report that the ability to radiolabel aromatic rings can be predicted by {sup 13}C-NMR chemical shifts, we have examined the generality of this correlation in aromatic rings bearing a variety of substituents. Although the original correlation holds for nitro substituted anisaldehydes, it cannot be extended to other rings substitution patterns. We have examined the relationship of in vivo localization of various fluorine-18 labeled dopamine uptake inhibitors to their in vitro binding affinities and lipophilicities. We have found that remarkably small decreases in binding affinity result in dramatic losses of in vivo binding to the desired high affinity binding sites. In order to probe the effects of endogenous neurotransmitter on the in vivo binding of radiolabeled dopamine uptake inhibitors, we have examined the in vivo regional localization of (18{sub F}) GBR 13119 after acute and chronic drug treatments which alter the endogenous levels of dopamine. We have found that acute changes in dopamine levels do not affect the binding of this radioligand, but chronic depletion of neurotransmitter results in down-regulation of the in vivo binding sites. 16 refs., 2 figs., 1 tab.

  18. Radiopharmaceuticals for diagnosis and treatment. Progress report

    SciTech Connect

    Kuhl, D.E.

    1992-12-01

    We report on our efforts in PET basic radiochemistry, radiopharmaceutical synthesis, and preclinical radiopharmaceutical evaluation. These efforts are focused on three fronts. First predictive abilities in nucleophilic aromatic substitution with [{sup 18}F]fluorination of substituted aromatic rings. Although radiochemical yields can be predicted within a very similar group of compounds with similar leaving groups and substituent patterns, generalization to all nucleophilic substitutions with [{sup 18}F] fluoride is not warranted. Kinetic studies indicate significantly different rates of reactions, depending on ring substituents. Second, preclinical evaluation of new radiopharmaceuticals. We have synthesized and begun the preclinical evaluation of [{sup 11}C]tetrabenazine, a new radioligand based on the vesicular monoamine transport system. Third, our work, on [{sup 18}F]fluorination/decarbonylation reactions, structure-activity relationships in dopamine uptake inhibitors and effects of chronic drugs on radioligand binding is described.

  19. Eleventh international symposium on radiopharmaceutical chemistry

    SciTech Connect

    1995-12-31

    This document contains abstracts of papers which were presented at the Eleventh International Symposium on Radiopharmaceutical Chemistry. Sessions included: radiopharmaceuticals for the dopaminergic system, strategies for the production and use of labelled reactive small molecules, radiopharmaceuticals for measuring metabolism, radiopharmaceuticals for the serotonin and sigma receptor systems, labelled probes for molecular biology applications, radiopharmaceuticals for receptor systems, radiopharmaceuticals utilizing coordination chemistry, radiolabelled antibodies, radiolabelling methods for small molecules, analytical techniques in radiopharmaceutical chemistry, and analytical techniques in radiopharmaceutical chemistry.

  20. Cyclotron produced radiopharmaceuticals

    NASA Astrophysics Data System (ADS)

    Kopička, K.; Fišer, M.; Hradilek, P.; Hanč, P.; Lebeda, O.

    2003-01-01

    Some of the cyclotron-produced radionuclides may serve as important materials for the production of radiopharmaceuticals. This lecture deals with basic information relating to various aspects of these compounds. In comparison with radionuclides/compounds used for non-medical purposes, radiopharmaceuticals are subject to a broader scale of regulations, both from the safety and efficacy point of view; besides that, there are both radioactive and medical aspects that must be taken into account for any radiopharmaceutical. According to the regulations and in compliance with general rules of work with radioactivity, radiopharmaceuticals should only be prepared/manufactured under special conditions, using special areas and special equipment and applying special procedures (e.g. sterilisation, disinfection, aseptic work). Also, there are special procedures for cleaning and maintenance. Sometimes the requirements for the product safety clash with those for the safety of the personnel; several examples of solutions pertaining to these cases are given in the lecture. Also, the specific role of cyclotron radiopharmaceuticals is discussed.

  1. Method for preparing radiopharmaceutical complexes

    DOEpatents

    Jones, Alun G.; Davison, Alan; Abrams, Michael J.

    1989-05-02

    A method for preparing radiopharmaceutical complexes that are substantially free of the reaction materials used to produce the radiopharmaceutical complex is disclosed. The method involves admixing in a suitable first solvent in a container a target seeking ligand or salt or metal adduct thereof, a radionuclide label, and a reducing agent for said radionuclide, thereby forming said radiopharmaceutical complex; coating the interior walls of the container with said pharmaceutical complex; discarding the solvent containing by-products and unreacted starting reaction materials; and removing the radiopharmaceutical complex from said walls by dissolving it in a second solvent, thereby obtaining said radiopharmaceutical complex substantially free of by-products and unreacted starting materials.

  2. Audits of radiopharmaceutical formulations.

    PubMed

    Castronovo, F P

    1992-03-01

    A procedure for auditing radiopharmaceutical formulations is described. To meet FDA guidelines regarding the quality of radiopharmaceuticals, institutional radioactive drug research committees perform audits when such drugs are formulated away from an institutional pharmacy. All principal investigators who formulate drugs outside institutional pharmacies must pass these audits before they can obtain a radiopharmaceutical investigation permit. The audit team meets with the individual who performs the formulation at the site of drug preparation to verify that drug formulations meet identity, strength, quality, and purity standards; are uniform and reproducible; and are sterile and pyrogen free. This team must contain an expert knowledgeable in the preparation of radioactive drugs; a radiopharmacist is the most qualified person for this role. Problems that have been identified by audits include lack of sterility and apyrogenicity testing, formulations that are open to the laboratory environment, failure to use pharmaceutical-grade chemicals, inadequate quality control methods or records, inadequate training of the person preparing the drug, and improper unit dose preparation. Investigational radiopharmaceutical formulations, including nonradiolabeled drugs, must be audited before they are administered to humans. A properly trained pharmacist should be a member of the audit team. PMID:1598931

  3. Process for preparing radiopharmaceuticals

    DOEpatents

    Barak, Morton; Winchell, Harry S.

    1977-01-04

    A process for the preparation of technetium-99m labeled pharmaceuticals is disclosed. The process comprises initially isolating technetium-99m pertechnetate by adsorption upon an adsorbent packing in a chromatographic column. The technetium-99m is then eluted from the packing with a biological compound to form a radiopharmaceutical.

  4. Pharmacovigilance in radiopharmaceuticals

    PubMed Central

    Kumar, Rishi; Kalaiselvan, Vivekanandan; Kumar, Rakesh; Verma, Ravendra; Singh, Gyanendra Nath

    2016-01-01

    Indian Pharmacopoeia Commission is Committed for maintaining the standards of drugs including Radiopharmaceuticals (RPs) by publishing Indian Pharmacopoeia. These RPs are being used in India for diagnostic or therapeutic purpose. RPs though contain relatively small quantities of active ingredient and administered in small volumes could cause some adverse reactions to the patients. The objective of presenting this article is to introduce the system of adverse drug reaction reporting to the nuclear medicine fraternity who are dealing with RPs. PMID:27095855

  5. Transport processes of radiopharmaceuticals and -modulators

    PubMed Central

    2011-01-01

    Radiotherapy and radiology have been indispensable components in cancer care for many years. The detection limit of small tumor foci as well as the development of radio-resistance and severe side effects towards normal tissues led to the development of strategies to improve radio-diagnostic and -therapeutic approaches by pharmaceuticals. The term "radiopharmaceutical" has been used for drugs labeled with radioactive tracers for therapy or diagnosis. In addition, drugs have been described to sensitize tumor cells to radiotherapy (radiosensitizers) or to protect normal tissues from detrimental effects of radiation (radioprotectors). The present review summarizes recent concepts on the transport of radiopharmaceuticals, radiosensitizers, and radioprotectors in cells and tissues, e.g. by ATP-binding cassette transporters such as P-glycoprotein. Strengths and weaknesses of current strategies to improve transport-based processes are discussed. PMID:21645349

  6. Radiopharmaceuticals in nuclear medicine practice

    SciTech Connect

    Kowalsky, R.J.; Perry, J.R.

    1987-01-01

    This book discusses the basic principles and clinical applications of radiopharmaceuticals. Topics include atomic physics as applied to radiopharmaceuticals, radionuclide generator function, nuclear pharmacy and safety, and radiopharmaceutical use in evaluating the major organ systems of the body. For each body system the author explains rationale for use, typical procedures, current agents of choice, and interpretation of results. Images, tables, and graphs illustrate normal and abnormal studies.

  7. Cyclotrons and positron emitting radiopharmaceuticals

    SciTech Connect

    Wolf, A.P.; Fowler, J.S.

    1984-01-01

    The state of the art of Positron Emission Tomography (PET) technology as related to cyclotron use and radiopharmaceutical production is reviewed. The paper discusses available small cyclotrons, the positron emitters which can be produced and the yields possible, target design, and radiopharmaceutical development and application. 97 refs., 12 tabs. (ACR)

  8. Unconventional Nuclides for Radiopharmaceuticals

    PubMed Central

    Holland, Jason P.; Williamson, Matthew J.; Lewis, Jason S.

    2016-01-01

    Rapid and widespread growth in the use of nuclear medicine for both diagnosis and therapy of disease has been the driving force behind burgeoning research interests in the design of novel radiopharmaceuticals. Until recently, the majority of clinical and basic science research has focused on the development of 11C-, 13N-, 15O-, and 18F-radiopharmaceuticals for use with positron emission tomography (PET) and 99mTc-labeled agents for use with single-photon emission computed tomography (SPECT). With the increased availability of small, low-energy cyclotrons and improvements in both cyclotron targetry and purification chemistries, the use of “nonstandard” radionuclides is becoming more prevalent. This brief review describes the physical characteristics of 60 radionuclides, including β+, β−, γ-ray, and α-particle emitters, which have the potential for use in the design and synthesis of the next generation of diagnostic and/or radiotherapeutic drugs. As the decay processes of many of the radionuclides described herein involve emission of high-energy γ-rays, relevant shielding and radiation safety issues are also considered. In particular, the properties and safety considerations associated with the increasingly prevalent PET nuclides 64Cu, 68Ga, 86Y, 89Zr, and 124I are discussed. PMID:20128994

  9. Radiopharmaceuticals for diagnosis and treatment. Progress report

    SciTech Connect

    Kuhl, D.E.

    1991-12-31

    In this grant period we have continued our efforts in the areas of PE basic radiochemistry, radiopharmaceutical synthesis, and preclinical radiopharmaceutical evaluation. A new synthetic sequence, consisting, of no-carrier-added fluorine-18 labeling of substituted benzaldehydes followed by reductive decarbonylation, has been developed. This new methodology can be applied to the fluorine-18 labeling of a wide variety of drugs not previously accessible through existing fluorine-18 labeling methods. Following up on a literature report that the ability to radiolabel aromatic rings can be predicted by {sup 13}C-NMR chemical shifts, we have examined the generality of this correlation in aromatic rings bearing a variety of substituents. Although the original correlation holds for nitro substituted anisaldehydes, it cannot be extended to other rings substitution patterns. We have examined the relationship of in vivo localization of various fluorine-18 labeled dopamine uptake inhibitors to their in vitro binding affinities and lipophilicities. We have found that remarkably small decreases in binding affinity result in dramatic losses of in vivo binding to the desired high affinity binding sites. In order to probe the effects of endogenous neurotransmitter on the in vivo binding of radiolabeled dopamine uptake inhibitors, we have examined the in vivo regional localization of [18{sub F}] GBR 13119 after acute and chronic drug treatments which alter the endogenous levels of dopamine. We have found that acute changes in dopamine levels do not affect the binding of this radioligand, but chronic depletion of neurotransmitter results in down-regulation of the in vivo binding sites. 16 refs., 2 figs., 1 tab.

  10. Receptor-binding radiopharmaceuticals for imaging breast tumors: estrogen-receptor interactions and selectivity of tissue uptake of halogenated estrogen analogs

    SciTech Connect

    Katzenellenbogen J.A.; Carlson, K.E.; Heiman, D.F.; Goswami, R.

    1980-06-01

    Four halogenated estrogen analogs - o-fluorohexestrol, and 1-fluoro-, 1-bromo-, and 1-iodohexestrol - have been prepared and tritium-labeled in high specific activity, to investigate their potential as estrogen-receptor-based agents for imaging breast tumors. These compounds bind with high affinity in vitro to the cytoplasmic uterine estrogen receptor from rat and lamb and sediment as 8S receptor complexes on sucrose gradients. After 1 hr in immature rats, these compounds show high uptake into the uterus, but low uptakes (10 to 25% of the uterine levels) into most nontarget tissues. The uterine uptake is estrogen specific since it is depressed by excess nonradioactive estradiol. Uptake selectivity is greatest for the fluorohexestrols and decreases for the bromo and iodo compounds. In mature rats bearing DMBA-induced mammary tumors, selective uptake by the uterus and tumors is seen with 1-fluoro(/sup 3/H/sub 4/)hexestrol and o-fluoro(/sup 3/H/sub 3/)hexestrol. The studies indicate that these four halogenated hexestrols are promising candidates as estrogen-receptor-based agents for the imaging of human breast tumors.

  11. Instrumentation and radiopharmaceutical validation.

    PubMed

    Zigler, S S

    2009-08-01

    Although the promise of new positron emission tomography (PET) imaging agents is great, the process of bringing these agents to commercialization remains in its infancy. There are no PET products today that have gone through the full clinical and chemistry development process required to gain marketing approval by the US Food and Drug Administration (FDA). The purpose of this paper was to review validation from the perspective of the chemistry, manufacturing and controls (CMC) section of an FDA filing, as well as the validation requirements described in FDA good manufacturing practice (GMP) regulations, guidance documents and general chapters of the US Pharmacopeia (USP). The review includes discussion of validation from development to commercial production of PET radiopharmaceuticals with a special emphasis on equipment and instrumentation used in production and testing. The goal is to stimulate a dialog that leads to the standardization of industry practices and regulatory requirements for validation practices in PET. PMID:19834450

  12. Aptamers as radiopharmaceuticals for nuclear imaging and therapy.

    PubMed

    Gijs, Marlies; Aerts, An; Impens, Nathalie; Baatout, Sarah; Luxen, André

    2016-04-01

    Today, radiopharmaceuticals belong to the standard instrumentation of nuclear medicine, both in the context of diagnosis and therapy. The majority of radiopharmaceuticals consist of targeting biomolecules which are designed to interact with a disease-related molecular target. A plethora of targeting biomolecules of radiopharmaceuticals exists, including antibodies, antibody fragments, proteins, peptides and nucleic acids. Nucleic acids have some significant advantages relative to proteinaceous biomolecules in terms of size, production, modifications, possible targets and immunogenicity. In particular, aptamers (non-coding, synthetic, single-stranded DNA or RNA oligonucleotides) are of interest because they can bind a molecular target with high affinity and specificity. At present, few aptamers have been investigated preclinically for imaging and therapeutic applications. In this review, we describe the use of aptamers as targeting biomolecules of radiopharmaceuticals. We also discuss the chemical modifications which are needed to turn aptamers into valuable (radio-)pharmaceuticals, as well as the different radiolabeling strategies that can be used to radiolabel oligonucleotides and, in particular, aptamers. PMID:26746572

  13. Dosimetry for Radiopharmaceutical Therapy

    PubMed Central

    Sgouros, George; Hobbs, Robert F.

    2014-01-01

    Radiopharmaceutical therapy (RPT) involves the use of radionuclides that are either conjugated to tumor-targeting agents (eg, nanoscale constructs, antibodies, peptides, and small molecules) or concentrated in tissue through natural physiological mechanisms that occur predominantly in neoplastic or otherwise targeted cells (eg, Graves disease). The ability to collect pharmacokinetic data by imaging and use this to perform dosimetry calculations for treatment planning distinguishes RPT from other systemic treatment modalities. Treatment planning has not been widely adopted, in part, because early attempts to relate dosimetry to outcome were not successful. This was partially because a dosimetry methodology appropriate to risk evaluation rather than efficacy and toxicity was being applied to RPT. The weakest links in both diagnostic and therapeutic dosimetry are the accuracy of the input and the reliability of the radiobiological models used to convert dosimetric data to the relevant biologic end points. Dosimetry for RPT places a greater demand on both of these weak links. To date, most dosimetric studies have been retrospective, with a focus on tumor dose-response correlations rather than prospective treatment planning. In this regard, transarterial radioembolization also known as intra-arterial radiation therapy, which uses radiolabeled (90Y) microspheres of glass or resin to treat lesions in the liver holds much promise for more widespread dosimetric treatment planning. The recent interest in RPT with alpha-particle emitters has highlighted the need to adopt a dosimetry methodology that specifically accounts for the unique aspects of alpha particles. The short range of alpha-particle emitters means that in cases in which the distribution of activity is localized to specific functional components or cell types of an organ, the absorbed dose will be equally localized and dosimetric calculations on the scale of organs or even voxels (~5 mm) are no longer sufficient

  14. Preparation of radiopharmaceuticals labeled with metal radionuclides

    SciTech Connect

    Welch, M.J.

    1992-06-01

    We recently developed a useful zinc-62/copper-62 generator and are presently evaluating copper-62 radiopharmaceuticals for clinical studies. While developing these copper-62 radiopharmaceuticals, in collaboration with the University of Missouri Research Reactor, Columbia we have also explored copper-64 radiopharmaceuticals. The PET images we obtained with copper-64 tracers were of such high quality that we have developed and evaluated copper-64 labeled antibodies for PET imaging. The major research activities described herein include: the development and assessment of gallium-68 radiopharmaceuticals; the development and evaluation of a new zinc-62/copper-62 generator and the assessment of copper-62 radiopharmaceuticals; mechanistic studies on proteins labeled with metal radionuclides.

  15. Bioinorganic Activity of Technetium Radiopharmaceuticals.

    ERIC Educational Resources Information Center

    Pinkerton, Thomas C.; And Others

    1985-01-01

    Technetium radiopharmaceuticals are diagnostic imaging agents used in the field of nuclear medicine to visualize tissues, anatomical structures, and metabolic disorders. Bioavailability of technetium complexes, thyroid imaging, brain imaging, kidney imaging, imaging liver function, bone imaging, and heart imaging are the major areas discussed. (JN)

  16. Radiopharmaceuticals for diagnosis. Final report

    SciTech Connect

    Not Available

    1994-03-01

    In the period 1969-1986, this project was directed to the evolution of target-specific labeled chemicals useful for nuclear medical imaging, especially radioactive indicators suited to tracing adrenal functions and localizing tumors in the neuroendocrine system. Since 1986, this project research has focused on the chemistry of positron emission tomography (PET) ligands. This project has involved the evaluation of methods for radiochemical syntheses with fluorine-18, as well as the development and preliminary evaluation of new radiopharmaceuticals for positron emission tomography. In the radiochemistry area, the ability to predict fluorine-18 labeling yields for aromatic substitution reactions through the use of carbon-13 NMR analysis was studied. Radiochemical yields can be predicted for some structurally analogous aromatic compounds, but this correlation could not be generally applied to aromatic substrates for this reaction, particularly with changes in ring substituents or leaving groups. Importantly, certain aryl ring substituents, particularly methyl groups, appeared to have a negative effect on fluorination reactions. These observations are important in the future design of syntheses of complicated organic radiopharmaceuticals. In the radiopharmaceutical area, this project has supported the development of a new class of radiopharmaceuticals based on the monoamine vesicular uptake systems. The new radioligands, based on the tetrabenazine structure, offer a new approach to the quantification of monoaminergic neurons in the brain. Preliminary primate imaging studies support further development of these radioligands for PET studies in humans. If successful, such radiopharmaceuticals will find application in studies of the causes and treatment of neurodegenerative disorders such as Parkinson`s disease.

  17. Radiopharmaceuticals for single-photon emission computed tomography brain imaging.

    PubMed

    Kung, Hank F; Kung, Mei-Ping; Choi, Seok Rye

    2003-01-01

    In the past 10 years, significant progress on the development of new brain-imaging agents for single-photon emission computed tomography has been made. Most of the new radiopharmaceuticals are designed to bind specific neurotransmitter receptor or transporter sites in the central nervous system. Most of the site-specific brain radiopharmaceuticals are labeled with (123)I. Results from imaging of benzodiazepine (gamma-aminobutyric acid) receptors by [(123)I]iomazenil are useful in identifying epileptic seizure foci and changes of this receptor in psychiatric disorders. Imaging of dopamine D2/D3 receptors ([(123)I]iodobenzamide and [(123)I]epidepride) and transporters [(123)I]CIT (2-beta-carboxymethoxy-3-beta(4-iodophenyl)tropane) and [(123)I]FP-beta-CIT (N-propyl-2-beta-carboxymethoxy-3-beta(4-iodophenyl)-nortropane has proven to be a simple but powerful tool for differential diagnosis of Parkinson's and other neurodegenerative diseases. A (99m)Tc-labeled agent, [(99m)Tc]TRODAT (technetium, 2-[[2-[[[3-(4-chlorophenyl)-8-methyl-8-azabicyclo [3,2,1]oct-2-yl]methyl](2-mercaptoethyl)amino]ethyl]amino] ethanethiolato(3-)]oxo-[1R-(exo-exo)]-), for imaging dopamine transporters in the brain has been successfully applied in the diagnosis of Parkinson's disease. Despite the fact that (123)I radiopharmaceuticals have been widely used in Japan and in Europe, clinical application of (123)I-labeled brain radiopharmaceuticals in the United States is limited because of the difficulties in supplying such agents. Development of (99m)Tc agents will likely extend the application of site-specific brain radiopharmaceuticals for routine applications in aiding the diagnosis and monitoring treatments of various neurologic and psychiatric disorders. PMID:12605353

  18. (Radiopharmaceutical and chemotherapeutic drug technology)

    SciTech Connect

    Srivastava, P.C.

    1988-01-14

    The purpose was to undertake a TOKTEN Distinguished Scientist Award assignment sponsored by the United Nations Development Programme (UNDP) in cooperation with the Council of Scientific and Industrial Research (CSIR) of India to conduct research in the areas of nucleosides and protein labeling agents at the Central Drug Research Institute (CDRI), Lucknow, and to help research scientists develop chemotherapeutic drugs in India. His work at CDRI consisted of syntheses of imidazole nucleosides, iodination reactions of nucleosides, synthesis of a bifunctional bismaleimide protein labeling agent, coordination of protein labeling studies with the Membrane Biology Group of CDRI, and initiation of several new collaborative research projects at CDRI. In addition, as a part of the CSIR-UNDP, the traveler visited several academic and industrial research institutions in India, delivered five seminars describing various aspects of radiopharmaceutical development at ORNL, and interacted extensively with scientists in India on current drug and radiopharmaceutical develop technologies in India and abroad.

  19. Radiopharmaceuticals for imaging the heart

    DOEpatents

    Green, M.A.; Tsang, B.W.

    1994-06-28

    Radiopharmaceuticals for imaging myocardial tissues are prepared by forming lipophilic, cationic complexes of radioactive metal ions with metal chelating ligands comprising the Schiff base adducts of triamines and tetraamines with optionally substituted salicylaldehydes. The lipophilic, cationic, radioactive complexes of the invention exhibit high uptake and retention in myocardial tissues. Preferred gallium-68(III) complexes in accordance with this invention can be used to image the heart using positron emission tomography. 6 figures.

  20. Radiopharmaceuticals for imaging the heart

    DOEpatents

    Green, Mark A.; Tsang, Brenda W.

    1994-01-01

    Radiopharmaceuticals for imaging myocardial tissues are prepared by forming lipophilic, cationic complexes of radioactive metal ions with metal chelating ligands comprising the Schiff base adducts of triamines and tetraamines with optionally substituted salicylaldehydes. The lipophilic, cationic, radioactive complexes of the invention exhibit high uptake and retention in myocardial tissues. Preferred gallium-68(III) complexes in accordance with this invention can be used to image the heart using positron emission tomography.

  1. Prospective of 68Ga-Radiopharmaceutical Development

    PubMed Central

    Velikyan, Irina

    2014-01-01

    Positron Emission Tomography (PET) experienced accelerated development and has become an established method for medical research and clinical routine diagnostics on patient individualized basis. Development and availability of new radiopharmaceuticals specific for particular diseases is one of the driving forces of the expansion of clinical PET. The future development of the 68Ga-radiopharmaceuticals must be put in the context of several aspects such as role of PET in nuclear medicine, unmet medical needs, identification of new biomarkers, targets and corresponding ligands, production and availability of 68Ga, automation of the radiopharmaceutical production, progress of positron emission tomography technologies and image analysis methodologies for improved quantitation accuracy, PET radiopharmaceutical regulations as well as advances in radiopharmaceutical chemistry. The review presents the prospects of the 68Ga-based radiopharmaceutical development on the basis of the current status of these aspects as well as wide range and variety of imaging agents. PMID:24396515

  2. Radiation dose estimates for radiopharmaceuticals

    SciTech Connect

    Stabin, M.G.; Stubbs, J.B.; Toohey, R.E.

    1996-04-01

    Tables of radiation dose estimates based on the Cristy-Eckerman adult male phantom are provided for a number of radiopharmaceuticals commonly used in nuclear medicine. Radiation dose estimates are listed for all major source organs, and several other organs of interest. The dose estimates were calculated using the MIRD Technique as implemented in the MIRDOSE3 computer code, developed by the Oak Ridge Institute for Science and Education, Radiation Internal Dose Information Center. In this code, residence times for source organs are used with decay data from the MIRD Radionuclide Data and Decay Schemes to produce estimates of radiation dose to organs of standardized phantoms representing individuals of different ages. The adult male phantom of the Cristy-Eckerman phantom series is different from the MIRD 5, or Reference Man phantom in several aspects, the most important of which is the difference in the masses and absorbed fractions for the active (red) marrow. The absorbed fractions for flow energy photons striking the marrow are also different. Other minor differences exist, but are not likely to significantly affect dose estimates calculated with the two phantoms. Assumptions which support each of the dose estimates appears at the bottom of the table of estimates for a given radiopharmaceutical. In most cases, the model kinetics or organ residence times are explicitly given. The results presented here can easily be extended to include other radiopharmaceuticals or phantoms.

  3. Hot atom chemistry and radiopharmaceuticals

    SciTech Connect

    Krohn, Kenneth A.; Moerlein, Stephen M.; Link, Jeanne M.; Welch, Michael J.

    2012-12-19

    The chemical products made in a cyclotron target are a combined result of the chemical effects of the nuclear transformation that made the radioactive atom and the bulk radiolysis in the target. This review uses some well-known examples to understand how hot atom chemistry explains the primary products from a nuclear reaction and then how radiation chemistry is exploited to set up the optimal product for radiosynthesis. It also addresses the chemical effects of nuclear decay. There are important principles that are common to hot atom chemistry and radiopharmaceutical chemistry. Both emphasize short-lived radionuclides and manipulation of high specific activity nuclides. Furthermore, they both rely on radiochromatographic separation for identification of no-carrieradded products.

  4. Radiopharmaceuticals in PET, progress and promise

    SciTech Connect

    Wolf, A.P.; Fowler, J.S.

    1988-11-01

    It is the intention of this presentation to focus on the current state of radiopharmaceuticals for PET and where this is leading us. PET radiopharmaceuticals can be broken down into perhaps seven categories at present with each being applicable to a different aspect of human biochemistry. These are: metabolic probes, neurochemical probes, enzyme probes, ion channel blockers, blood flow agents, ethical drugs and other positron emitters. 7 refs.

  5. Radiopharmaceuticals in PET, Progress and Promise

    DOE R&D Accomplishments Database

    Wolf, A. P.; Fowler, J. S.

    1988-11-01

    It is the intention of this presentation to focus on the current state of radiopharmaceuticals for PET and where this is leading us. PET radiopharmaceuticals can be broken down into perhaps seven categories at present with each being applicable to a different aspect of human biochemistry. These are: metabolic probes, neurochemical probes, enzyme probes, ion channel blockers, blood flow agents, ethical drugs and other positron emitters.

  6. Rational development of radiopharmaceuticals for HIV-1.

    PubMed

    Lau, Chuen-Yen; Maldarelli, Frank; Eckelman, William C; Neumann, Ronald D

    2014-04-01

    The global battle against HIV-1 would benefit from a sensitive and specific radiopharmaceutical to localize HIV-infected cells. Ideally, this probe would be able to identify latently infected host cells containing replication competent HIV sequences. Clinical and research applications would include assessment of reservoirs, informing clinical management by facilitating assessment of burden of infection in different compartments, monitoring disease progression and monitoring response to therapy. A "rational" development approach could facilitate efficient identification of an appropriate targeted radiopharmaceutical. Rational development starts with understanding characteristics of the disease that can be effectively targeted and then engineering radiopharmaceuticals to hone in on an appropriate target, which in the case of HIV-1 (HIV) might be an HIV-specific product on or in the host cell, a differentially expressed gene product, an integrated DNA sequence specific enzymatic activity, part of the inflammatory response, or a combination of these. This is different from the current approach that starts with a radiopharmaceutical for a target associated with a disease, mostly from autopsy studies, without a strong rationale for the potential to impact patient care. At present, no targeted therapies are available for HIV latency, although a number of approaches are under study. Here we discuss requirements for a radiopharmaceutical useful in strategies targeting persistently infected cells. The radiopharmaceutical for HIV should be developed based on HIV biology, studied in an animal model and then in humans, and ultimately used in clinical and research settings. PMID:24607432

  7. Dopamine D-2 receptor imaging radiopharmaceuticals: synthesis, radiolabeling, and in vitro binding of (R)-(+)- and (S)-(-)-3-iodo-2-hydroxy-6-methoxy-N- ((1-ethyl-2-pyrrolidinyl)methyl)benzamide

    SciTech Connect

    Kung, H.F.; Kasliwal, R.; Pan, S.G.; Kung, M.P.; Mach, R.H.; Guo, Y.Z.

    1988-05-01

    In developing central nervous system (CNS) dopamine D-2 receptor imaging agents, enantiomers, R-(+) and S-(-) isomers, of 3-(/sup 125/I)iodo-2-hydroxy-6-methoxy-N-((1-ethyl-2- pyrrolidinyl)methyl)benzamide, (/sup 125/I)IBZM, were synthesized, and their in vitro binding characteristics were evaluated in rat striatum tissue preparation. The (S)-(-)-(/sup 125/I)IBZM showed high specific dopamine D-2 receptor binding (Kd = 0.43 nM, Bmax = 0.48 pmol/mg of protein). Competition data of various ligands for IBZM binding displayed the following rank order of potency: spiperone greater than (S)-(-)-IBZM greater than (+)-butaclamol much greater than (R)-(+)-IBZM greater than (S)-(-)-BZM greater than dopamine greater than ketanserin greater than SCH23390 much greater than propanolol. The results indicate that (/sup 125/I)IBZM binds specifically to the dopamine D-2-receptor with stereospecificity. The (/sup 125/I)IBZM is potentially useful as an imaging agent for the investigation of dopamine D-2 receptors in humans.

  8. Astatine Radiopharmaceuticals: Prospects and Problems

    PubMed Central

    Vaidyanathan, Ganesan; Zalutsky, Michael R.

    2010-01-01

    For the treatment of minimum residual diseases such micrometastases and residual tumor margins that remain after debulking of the primary tumor, targeted radiotherapy using radiopharmaceuticals tagged with α-particle-emitting radionuclides is very attractive. In addition to the their short range in tissue, which helps minimize harmful effects on adjacent normal tissues, α-particles, being high LET radiation, have several radiobiological advantages. The heavy halogen, astatine-211 is one of the prominent α-particle-emitting radionuclides in practice. Being a halogen, it can often be incorporated into biomolecules of interest by adapting radioiodination chemistry. A wide spectrum of compounds from the simple [211At]astatide ion to small organic molecules, peptides, and large proteins labeled with 211At have been investigated with at least two reaching the stage of clinical evaluation. The chemistry, cytotoxic advantages, biodistribution studies, and microdosimetry/pharmacokinetic modeling of some of these agents will be reviewed. In addition, potential problems such as the harmful effect of radiolysis on the synthesis, lack of sufficient in vivo stability of astatinated compounds, and possible adverse effects when they are systemically administered will be discussed. PMID:20150978

  9. Astatine Radiopharmaceuticals: Prospects and Problems.

    PubMed

    Vaidyanathan, Ganesan; Zalutsky, Michael R

    2008-09-01

    For the treatment of minimum residual diseases such micrometastases and residual tumor margins that remain after debulking of the primary tumor, targeted radiotherapy using radiopharmaceuticals tagged with alpha-particle-emitting radionuclides is very attractive. In addition to the their short range in tissue, which helps minimize harmful effects on adjacent normal tissues, alpha-particles, being high LET radiation, have several radiobiological advantages. The heavy halogen, astatine-211 is one of the prominent alpha-particle-emitting radionuclides in practice. Being a halogen, it can often be incorporated into biomolecules of interest by adapting radioiodination chemistry. A wide spectrum of compounds from the simple [(211)At]astatide ion to small organic molecules, peptides, and large proteins labeled with (211)At have been investigated with at least two reaching the stage of clinical evaluation. The chemistry, cytotoxic advantages, biodistribution studies, and microdosimetry/pharmacokinetic modeling of some of these agents will be reviewed. In addition, potential problems such as the harmful effect of radiolysis on the synthesis, lack of sufficient in vivo stability of astatinated compounds, and possible adverse effects when they are systemically administered will be discussed. PMID:20150978

  10. Radiopharmaceutical and Gene Therapy Program

    SciTech Connect

    Buchsbaum, Donald J.

    2006-02-09

    The objective of our research program was to determine whether novel receptors can be induced in solid cancers as a target for therapy with radiolabeled unmodified peptides that bind to the receptors. The hypothesis was that induction of a high number of receptors on the surface of these cancer cells would result in an increased uptake of the radiolabeled monomeric peptides as compared to published results with radiolabeled antibodies or peptides to naturally expressed antigens or receptors, and therefore a better therapeutic outcome. The following is a summary of published results.

  11. Simplification of Methods for PET Radiopharmaceutical Syntheses

    SciTech Connect

    Kilbourn, Michael, R.

    2011-12-27

    In an attempt to develop simplified methods for radiochemical synthesis of radiopharmaceuticals useful in Positron Emission Tomography (PET), current commercially available automated synthesis apparati were evaluated for use with solid phase synthesis, thin-film techniques, microwave-accelerated chemistry, and click chemistry approaches. Using combinations of these techniques, it was shown that these automated synthesis systems can be simply and effectively used to support the synthesis of a wide variety of carbon-11 and fluorine-18 labeled compounds, representing all of the major types of compounds synthesized and using all of the common radiochemical precursors available. These techniques are available for use to deliver clinically useful amounts of PET radiopharmaceuticals with chemical and radiochemical purities and high specific activities, suitable for human administration.

  12. Diagnostic radiopharmaceuticals for localization in target tissues exhibiting a regional PH shift relative to surrounding tissues

    SciTech Connect

    Blau, M.; Kung, H. F.

    1984-10-02

    A radiopharmaceutical chemical compound comprising a radioactive isotope, other than an isotope of iodine, in chemical combination with at least one amine group. The compound has a lipophilicity sufficiently high at a pH of 7.6 to permit passage of the compound from the blood of a mammal into a target organ or tissue and sufficiently low at a pH of 6.6 to prevent rapid return of the compound from the target organ or tissue to the blood. The compound has a percent protein binding of less than ninety percent. A method for selectively depositing a radiopharmaceutical compound in at least one target tissue or organ of a mammal, which tissue or organ has a significantly different intracellular pH than the blood of the mammal, by introducing the compound of the invention into the bloodstream of the mammal.

  13. Advances in the robotic production of radiopharmaceuticals

    SciTech Connect

    Gaehle, G.; Welch, M.J.

    1994-12-31

    A variety of robotic systems, including Zymark, Hudson Control Group, Anotech, and Questech formerly U.M.I, have been used as a reliable and safe way to produce radiopharmaceuticals. A robotic system`s ability allows it to produce a variety of radiopharmaceuticals on a routine basis including final preparation and quality control. With proper scheduling, a single robotic system can synthesize {sup 18}F-fluorodeoxyglucose, {sup 18}F-estradiol, {sup 11}C-acetate, {sup 68}Ga-citrate and at the same time control black box type syntheses such as {sup 15}O-butanol in a single day. A robotic system`s flexibility allows it to be used in designing and testing new syntheses, thus making the development of the new radiopharmaceuticals safer for the chemist. The development of Windows, a multi-tasking operating system for PC computers, allows a robot controlled by that computer to function simultaneously with a large variety of other systems. This increases the system`s ability to communicate with other systems and it allows for change without replacing the entire system. Improvements in robot technology has increased their reliability while making them competitive in price to other means of automation. Today a robotic system to produce {sup 18}F-fluorodeoxyglucose can cost as little as $55,000 U.S. depending on the cost of the hot cell.

  14. Tc-99m-galactosyl-neoglycoalbumin: in vivo characterization of receptor-mediated binding to hepatocyctes

    SciTech Connect

    Vera, D.R.; Krohn, K.A.; Stadalnik, R.C.; Scheibe, P.O.

    1984-04-01

    The biodistribution and kinetics of a receptor-binding hepatic radiopharmaceutical, Tc-99m-galactosyl-neoglycoalbumin (Tc-NGA), were investigated using mammalian and avian models. The radiopharmaceutical exhibited four significant features associated with receptor-mediated binding at the hepatocyte membrane in mammals: (a) high tissue specificity, (b) high molecular specificity, (c) affinity-dependent uptake, and (d) dose-dependent uptake. Diminished hepatic uptake by the avian model illustrated low nonspecific binding. The kinetic sensitivity to ligand-receptor affinity and stoichiometry illustrated the principal feature of receptor-binding radiopharmaceuticals, namely, quantitative assessment of tissue function based upon the biochemical interaction of a ligand and its specific receptor.

  15. Pitfalls and Limitations of SPECT, PET, and Therapeutic Radiopharmaceuticals.

    PubMed

    Ballinger, James R

    2015-09-01

    Radiopharmaceuticals are widely accepted to be a very safe class of drugs, with very few adverse reactions and unexpected biodistributions. However, problems can arise because of technical issues in manufacture or reconstitution, patient preparation, or drug administration. This review presents highlights of issues that have arisen in the newer classes of radiopharmaceuticals in the last 20 years and expands the scope of the previous report to include PET and therapeutic radiopharmaceuticals. Variations in the "quality" of the eluate of a (99)Mo/(99m)Tc generator remain a major issue. Several of the newer (99m)Tc tracers require a heating step in preparation that can also lead to unacceptably low radiochemical purity. Radiolytic breakdown can be a problem with all classes of radiopharmaceuticals. Many of the newer radiopharmaceuticals localize by receptor- or transporter-mediated processes and thus can be affected by other drugs, making patient preparation more important than ever. Therapeutic radiopharmaceuticals may require coadministration of radioprotectant regimens, such as the use of lysine-arginine infusions with radiopeptide therapy. Extravasation can have serious consequences with therapeutic radiopharmaceuticals. Adverse reactions to newer radiopharmaceuticals remain rare, though may increase because of coadministration of agents such as contrast media. However, there is known to be underreporting of minor adverse reactions. Knowledge of the pitfalls that can occur with radiopharmaceuticals is important in the interpretation of nuclear medicine images and optimal patient care. PMID:26278857

  16. Preparation of Radiopharmaceuticals Labeled with Metal Radionuclides

    SciTech Connect

    Welch, M.J.

    2012-02-16

    The overall goal of this project was to develop methods for the production of metal-based radionuclides, to develop metal-based radiopharmaceuticals and in a limited number of cases, to translate these agents to the clinical situation. Initial work concentrated on the application of the radionuclides of Cu, Cu-60, Cu-61 and Cu-64, as well as application of Ga-68 radiopharmaceuticals. Initially Cu-64 was produced at the Missouri University Research Reactor and experiments carried out at Washington University. A limited number of studies were carried out utilizing Cu-62, a generator produced radionuclide produced by Mallinckrodt Inc. (now Covidien). In these studies, copper-62-labeled pyruvaldehyde Bis(N{sup 4}-methylthiosemicarbazonato)-copper(II) was studied as an agent for cerebral myocardial perfusion. A remote system for the production of this radiopharmaceutical was developed and a limited number of patient studies carried out with this agent. Various other copper radiopharmaceuticals were investigated, these included copper labeled blood imaging agents as well as Cu-64 labeled antibodies. Cu-64 labeled antibodies targeting colon cancer were translated to the human situation. Cu-64 was also used to label peptides (Cu-64 octriatide) and this is one of the first applications of a peptide radiolabeled with a positron emitting metal radionuclide. Investigations were then pursued on the preparation of the copper radionuclides on a small biomedical cyclotron. A system for the production of high specific activity Cu-64 was developed and initially the Cu-64 was utilized to study the hypoxic imaging agent Cu-64 ATSM. Utilizing the same target system, other positron emitting metal radionuclides were produced, these were Y-86 and Ga-66. Radiopharmaceuticals were labeled utilizing both of these radionuclides. Many studies were carried out in animal models on the uptake of Cu-ATSM in hypoxic tissue. The hypothesis is that Cu-ATSM retention in vivo is dependent upon the

  17. Consequences of electroplated targets on radiopharmaceutical preparations

    NASA Astrophysics Data System (ADS)

    Finn, R. D.; Tirelli, S.; Sheh, Y.; Knott, A.; Gelbard, A. S.; Larson, S. M.; Dahl, J. R.

    1991-05-01

    The staff of the cyclotron facility at Memorial Sloan-Kettering Cancer Center is involved in a comprehensive radionuclide preparation program which culminates with the formulation of numerous requested short-lived, positron-emitting radiopharmaceutical agents for clinical investigation. Both the produced radionuclide as well as the final radiolabeled compound are subjected to stringent quality control standards including assays for radiochemical and chemical purity. The subtle chemical consequences resulting from the irradiation of a nickel-plated target for 13N production serve to emphasize some of these potential technical difficulties.

  18. Small Molecule Radiopharmaceuticals – A Review of Current Approaches

    PubMed Central

    Chaturvedi, Shubhra; Mishra, Anil K.

    2016-01-01

    Radiopharmaceuticals are an integral component of nuclear medicine and are widely applied in diagnostics and therapy. Though widely applied, the development of an “ideal” radiopharmaceutical can be challenging. Issues such as specificity, selectivity, sensitivity, and feasible chemistry challenge the design and synthesis of radiopharmaceuticals. Over time, strategies to address the issues have evolved by making use of new technological advances in the fields of biology and chemistry. This review presents the application of few advances in design and synthesis of radiopharmaceuticals. The topics covered are bivalent ligand approach and lipidization as part of design modifications for enhanced selectivity and sensitivity and novel synthetic strategies for optimized chemistry and radiolabeling of radiopharmaceuticals. PMID:26942181

  19. Placental transfer of radiopharmaceuticals and dosimetry in pregnancy

    SciTech Connect

    Russell, J.R.; Stabin, M.G.; Sparks, R.B.

    1999-01-01

    The calculation of radiation dose estimates to the fetus is often important in nuclear medicine. To obtain the best estimates of radiation dose to the fetus, the best biological and physical models should be employed. In this paper, after identification of radiopharmaceuticals often administered to women of childbearing age, the most recent data available on the placental crossover of these radiopharmaceuticals was used (with standard kinetic models describing the maternal distribution and retention and with the best available physical models) to obtain fetal dose estimates for these radiopharmaceuticals were identified as those most commonly administered to women of childbearing years. The literature yielded information on placental crossover of 15 radiopharmaceuticals, from animal or human data. Radiation dose estimates are presented in early pregnancy and at 3-, 6-, and 9-months gestation for these radiopharmaceuticals, as well as for many others used in nuclear medicine (the latter considering only maternal organ contributions to fetal dose). 46 refs., 1 fig., 5 tabs.

  20. Radiopharmaceutical dosage selection for pediatric nuclear medicine

    SciTech Connect

    Shore, R.M.; Hendee, W.R.

    1986-02-01

    To identify the most rational method for adjusting adult radiopharmaceutical dosages for children, four methods of dosage computation were examined from the perspectives of diagnostic adequacy and radiation absorbed dose. For static imaging, information density is the most important factor in study quality, and adjustment of dosage by body weight (Wt) for thick organs, and body surface area (BSA) for thin organs is recommended. Compared with adults, small children receive less radiation exposure if radiopharmaceutical dosages are adjusted by Wt, and slightly greater exposure if dosages are adjusted by BSA. For dynamic imaging studies, dosage requirements are governed by the spatial resolution needed for region of interest assignment, and the statistical reliability of the time-activity data. For dynamic renal imaging, renograms of similar quality are obtained if dosages are adjusted by height (Ht). Dynamic cardiac studies might appear to require dosages even larger than those adjusted by Ht which would result in higher radiation absorbed doses to pediatric patients. However, smaller dosages can be used in children by prolonging the imaging time and accepting lower temporal resolution. Dosage requirements for dynamic studies depend on which physiologic characteristics are measured from the time-activity data. Since the measurements of some characteristics demand higher count rates than others, dosage requirements ultimately depend on which measurements are clinically necessary. Close attention to the factors that determine these requirements may yield significant reduction in dosages, and thus in radiation exposure, for patients of all ages.

  1. Radiopharmaceutical Therapy in the Era of Precision Medicine*

    PubMed Central

    Sgouros, George; Goldenberg, David M.

    2014-01-01

    Precision medicine is the selection of a treatment modality that is specifically tailored to the genetic and phenotypic characteristics of a particular patient’s disease. In cancer, the objective is to treat with agents that inhibit cell signaling pathways that drive uncontrolled proliferation and dissemination of the disease. To overcome the eventual resistance to pathway inhibition therapy, this treatment modality has been combined with chemotherapy. We propose that pathway inhibition therapy is more rationally combined with radiopharmaceutical therapy (RPT), a cytotoxic treatment that is also targeted. RPT exploits pharmaceuticals that either bind specifically to tumors or accumulate by a broad array of physiological mechanisms indigenous to the neoplastic cells to deliver radiation specifically to these cells. Consistent with pathway inhibition therapy and in contrast to chemotherapy, RPT is well tolerated. However, the potential of RPT has not been fully exploited; for the most part, treatment has been implemented without using the ability to customize RPT by imaging and deriving individual patient tumor and normal organ radiation absorbed doses. These are more closely related to biological response and their determination should enable RPT treatment administration to maximum therapeutic benefit by treating to normal organ tolerance or demonstrating futility via tumor dosimetry. This is the essence of precision medicine. PMID:24953565

  2. Manufacture of radiopharmaceuticals-recent advances

    SciTech Connect

    Krieger, J.K.

    1996-12-31

    Trends in radiopharmaceutical manufacturing have been influenced by the demands of the regulatory agencies, the demands of the customers, and the ever-increasing complexity of new products. Process improvements resulting from automation in the production of radionuclides for diagnostic imaging products, {sup 99m}/Tc generators, {sup 67}Ga, and {sup 201}Tl have been introduced to enhance compliance with current good manufacturing practices and to improve worker safety, both by reducing dose in accord with as low as reasonably achievable levels of radiation and by providing an ergonomically sound environment. Tighter process control has resulted in less lot-to-lot variability and ensures reliability of supply. Reduced manufacturing lapse time for {sup 99m}Tc generators minimizes decay and conserves the supply of {sup 99}Mo. Automation has resulted in an even greater degree of remote operation and has led to reductions in dose, improved process control, and faster throughput in the manufacture of radionuclides.

  3. Cancer-targeted therapies and radiopharmaceuticals.

    PubMed

    Rachner, Tilman D; Jakob, Franz; Hofbauer, Lorenz C

    2015-01-01

    The treatment of bone metastases remains a clinical challenge. Although a number of well-established agents, namely bisphosphonates and denosumab, are available to reduce the occurrence of skeletal-related events, additional cancer-targeted therapies are required to improve patients' prognosis and quality of life. This review focuses on novel targets and agents that are under clinical evaluation for the treatment of malignant bone diseases such as activin A, src and endothelin-1 inhibition or agents that are clinically approved and may positively influence bone, such as the mTOR inhibitor everolimus. In addition, the potential of alpharadin, a novel radiopharmaceutical approved for the treatment of prostatic bone disease, is discussed. PMID:26131359

  4. Metallic radionuclides in the development of diagnostic and therapeutic radiopharmaceuticals.

    PubMed

    Bhattacharyya, Sibaprasad; Dixit, Manish

    2011-06-21

    Metallic radionuclides are the mainstay of both diagnostic and therapeutic radiopharmaceuticals. Therapeutic nuclear medicine is less advanced but has tremendous potential if the radionuclide is accurately targeted. Great interest exists in the field of inorganic chemistry for developing target specific radiopharmaceuticals based on radiometals for non-invasive disease detection and cancer radiotherapy. This perspective will focus on the nuclear properties of a few important radiometals and their recent applications to developing radiopharmaceuticals for imaging and therapy. Other topics for discussion will include imaging techniques, radiotherapy, analytical techniques, and radiation safety. The ultimate goal of this perspective is to introduce inorganic chemists to the field of nuclear medicine and radiopharmaceutical development, where many applications of fundamental inorganic chemistry can be found. PMID:21541393

  5. Application of a Small Molecule Radiopharmaceutical Concept to Improve Kinetics.

    PubMed

    Jeong, Jae Min

    2016-06-01

    Recently, large molecules or nanoparticles are actively studied as radiopharmaceuticals. However, their kinetics is problematic because of a slow penetration through the capillaries and slow distribution to the target. To improve the kinetics, a two-step targeting method can be applied by using small molecules and very rapid copper-free click reaction. Although this method might have limitations such as internalization of the first targeted conjugate, it will provide high target-to-non-target ratio imaging of radiopharmaceuticals. PMID:27275356

  6. Receptor-specific positron emission tomography radiopharmaceuticals: /sup 75/Br-labeled butyrophenone neuroleptics

    SciTech Connect

    Moerlein, S.M.; Stoecklin, G.; Weinhard, K.; Pawlik, G.; Heiss, W.D.

    1985-11-01

    Cerebral dopaminergic D/sub 2/ receptors are involved in several common disease states, such as schizophrenia, Parkinson's disease, and Huntington's chorea. The use of radiolabeled D/sub 2/ receptor-binding ligands with positron emission tomography (PET) to noninvasively quantitate D/sub 2/ receptor densities thus has potential application in medicine. Butyrophenone neuroleptics have a high in vitro and in vivo binding affinity for cerebral D/sub 2/ receptors, and due to the useful chemical and nuclear decay properties of /sup 74/Br (76% ..beta../sup +/, half-life = 1.6 h), the authors have evaluated radiobrominated bromospiperone (BSP), brombenperidol (BBP), and bromperidol (BP) as radiopharmaceuticals for use with PET.

  7. Skin contamination by radiopharmaceuticals and decontamination strategies.

    PubMed

    Bolzinger, M A; Bolot, C; Galy, G; Chabanel, A; Pelletier, J; Briançon, S

    2010-12-15

    The aim of the present study was to evaluate the percutaneous penetration of five common radiopharmaceuticals ((99m)Tc, (67)Ga, (125)I, (111)In and (51)Cr) and to evaluate the effect of decontamination by a detergent solution dedicated to hospital institutions for that purpose. The skin kinetic profiles were established by using the in vitro Franz cell method over 24h. The skin distribution in each skin layer was quantified after 6h exposure time and the efficacy of the detergent solution to remove radionuclides was evaluated also after 6h. The most striking result was the repartition into two classes of kinetic profiles: (125)I and (99m)Tc permeated quickly (∼60% of applied activity after 24h) while the 3 other radionuclides permeated slowly (from ∼2.75% for (67)Ga to ∼10% of applied activity for (111)In). The lag times, i.e. the time necessary to cross the skin varied from 20min for (99m)Tc to 5h for (51)Cr, which accumulated in skin compartments. Skin washings with the detergent solution were particularly efficient for this radionuclide, contrary to the others for which the washing procedure should be applied earlier. The permeation of ions was dependent on their chemical and physical forms and on their salting-in or salting-out effects (coordination state and Hofmeister series). PMID:20888404

  8. Stroma Targeting Nuclear Imaging and Radiopharmaceuticals

    PubMed Central

    Shetty, Dinesh; Jeong, Jae-Min; Shim, Hyunsuk

    2012-01-01

    Malignant transformation of tumor accompanies profound changes in the normal neighboring tissue, called tumor stroma. The tumor stroma provides an environment favoring local tumor growth, invasion, and metastatic spreading. Nuclear imaging (PET/SPECT) measures biochemical and physiologic functions in the human body. In oncology, PET/SPECT is particularly useful for differentiating tumors from postsurgical changes or radiation necrosis, distinguishing benign from malignant lesions, identifying the optimal site for biopsy, staging cancers, and monitoring the response to therapy. Indeed, PET/SPECT is a powerful, proven diagnostic imaging modality that displays information unobtainable through other anatomical imaging, such as CT or MRI. When combined with coregistered CT data, [18F]fluorodeoxyglucose ([18F]FDG)-PET is particularly useful. However, [18F]FDG is not a target-specific PET tracer. This paper will review the tumor microenvironment targeting oncologic imaging such as angiogenesis, invasion, hypoxia, growth, and homing, and also therapeutic radiopharmaceuticals to provide a roadmap for additional applications of tumor imaging and therapy. PMID:22685650

  9. (Coordinated research of chemotherapeutic agents and radiopharmaceuticals)

    SciTech Connect

    Srivastava, P.C.

    1991-01-14

    The traveler received a United Nations Development Program (UNDP) Award for Distinguished Scientists to visit Indian Research Institutions including Central Drug Research Institute (CDRI), Lucknow, the host institution, in cooperation with the Council of Scientific and Industrial Research (CSIR) of India. At CDRI, the traveler had meetings to discuss progress and future directions of on-going collaborative research work on nucleosides and had the opportunity to initiate new projects with the divisions of pharmacology, biopolymers, and membrane biology. As a part of this program, the traveler also visited Sanjay Gandhi Post Graduate Institute (SGPI) of Medical Sciences, Lucknow; Board of Radiation and Isotope Technology (BRIT) and Bhabha Atomic Research Center (BARC), Bombay; Variable Energy Cyclotron Center (VECC) and Indian Institute of Chemical Biology, Calcutta. He also attended the Indo-American Society of Nuclear Medicine Meeting held in Calcutta. The traveler delivered five seminars describing various aspects of radiopharmaceutical development at the Oak Ridge National Laboratory (ORNL) and discussed the opportunities for exchange visits to ORNL by Indian scientists.

  10. Auger Emitting Radiopharmaceuticals for Cancer Therapy

    NASA Astrophysics Data System (ADS)

    Falzone, Nadia; Cornelissen, Bart; Vallis, Katherine A.

    Radionuclides that emit Auger electrons have been of particular interest as therapeutic agents. This is primarily due to the short range in tissue, controlled linear paths and high linear energy transfer of these particles. Taking into consideration that ionizations are clustered within several cubic nanometers around the point of decay the possibility of incorporating an Auger emitter in close proximity to the cancer cell DNA has immense therapeutic potential thus making nuclear targeted Auger-electron emitters ideal for precise targeting of cancer cells. Furthermore, many Auger-electron emitters also emit γ-radiation, this property makes Auger emitting radionuclides a very attractive option as therapeutic and diagnostic agents in the molecular imaging and management of tumors. The first requirement for the delivery of Auger emitting nuclides is the definition of suitable tumor-selective delivery vehicles to avoid normal tissue toxicity. One of the main challenges of targeted radionuclide therapy remains in matching the physical and chemical characteristics of the radionuclide and targeting moiety with the clinical character of the tumor. Molecules and molecular targets that have been used in the past can be classified according to the carrier molecule used to deliver the Auger-electron-emitting radionuclide. These include (1) antibodies, (2) peptides, (3) small molecules, (4) oligonucleotides and peptide nucleic acids (PNAs), (5) proteins, and (6) nanoparticles. The efficacy of targeted radionuclide therapy depends greatly on the ability to increase intranuclear incorporation of the radiopharmaceutical without compromising toxicity. Several strategies to achieve this goal have been proposed in literature. The possibility of transferring tumor therapy based on the emission of Auger electrons from experimental models to patients has vast therapeutic potential, and remains a field of intense research.

  11. Relationship between lipophilicity and brain extraction of C-11-labeled radiopharmaceuticals. [Baboons

    SciTech Connect

    Dischino, D.D.; Welch, M.J.; Kilbourn, M.R.; Raichle, M.E.

    1983-11-01

    The brain extraction of fifteen C-11-labeled compounds during a single capillary transit was studied in adult baboons by external detection of these tracers after injection into the internal carotid artery. The log P/sub oct/ (partition coefficient for octanol/water) values of these compounds range from -0.7 to greater than 4.0. A parabolic relationship was found between the log P/sub oct/value of the C-11-labeled compounds and the fraction of the radiopharmaceutical entering the brain. Compounds with log P/sub oct/ values between 0.9 and 2.5 were found to pass freely across the blood-brain barrier at a cerebral blood flow of 100 ml-min/sup -1/-hg/sup -1/. An apparently decreased extraction of very lipophilic compounds was shown to be related to binding of the tracer to blood components and macromolecules (red blood cells, albumin, etc.). These data suggest that a radiopharmaceutical designed to measure blood flow should have a log P/sub oct/ value of between 0.9 and 2.5.

  12. Applications of quantitative whole body autoradiographic technique in radiopharmaceutical research

    SciTech Connect

    Som, P.; Oster, Z.H.; Yonekura, Y.; Meyer, M.A.; Fand, I.; Brill, A.B.

    1982-01-01

    The routine evaluation of radiopharmaceuticals involves dissecting tissue distribution studies (DTDS) and gamma or positron imaging. DTDS have the following disadvantages: since not all tissues can always be sampled, sites of radiopharmaceutical uptake may be missed and because the procedure involves weighing of dissected tissue samples, the spatial resolution of this method is low and determined by the smallest amount that can be weighed accurately. Gamma camera imaging and positron emission tomography though more comprehensive in evaluating the global distribution of a compound, have relative low spatial resolution. Whole body autoradiography of small animals has a much higher spatial resolution as compared to the above and depicts the global distribution of radiopharmaceuticals. A computer-assisted quantification method of WBARG applied to positron, beta, and gamma emitters will complement the method by producing quantitative values comparable to those obtained by dissection and direct tissue counting, with the advantages of depicting the global distribution at high spatial resolution.

  13. Newer positron emission tomography radiopharmaceuticals for radiotherapy planning: an overview

    PubMed Central

    Mukherjee, Anirban

    2016-01-01

    Positron emission tomography-computed tomography (PET-CT) has changed cancer imaging in the last decade, for better. It can be employed for radiation treatment planning of different cancers with improved accuracy and outcomes as compared to conventional imaging methods. 18F-fluorodeoxyglucose remains the most widely used though relatively non-specific cancer imaging PET tracer. A wide array of newer PET radiopharmaceuticals has been developed for targeted imaging of different cancers. PET-CT with such new PET radiopharmaceuticals has also been used for radiotherapy planning with encouraging results. In the present review we have briefly outlined the role of PET-CT with newer radiopharmaceuticals for radiotherapy planning and briefly reviewed the available literature in this regard. PMID:26904575

  14. Preparation of radiopharmaceuticals labeled with metal radionuclides. Progress report, July 1, 1988--June 30, 1992

    SciTech Connect

    Welch, M.J.

    1992-06-01

    We recently developed a useful zinc-62/copper-62 generator and are presently evaluating copper-62 radiopharmaceuticals for clinical studies. While developing these copper-62 radiopharmaceuticals, in collaboration with the University of Missouri Research Reactor, Columbia we have also explored copper-64 radiopharmaceuticals. The PET images we obtained with copper-64 tracers were of such high quality that we have developed and evaluated copper-64 labeled antibodies for PET imaging. The major research activities described herein include: the development and assessment of gallium-68 radiopharmaceuticals; the development and evaluation of a new zinc-62/copper-62 generator and the assessment of copper-62 radiopharmaceuticals; mechanistic studies on proteins labeled with metal radionuclides.

  15. Process for producing astatine-211 for radiopharmaceutical use

    DOEpatents

    Mirzadeh, S.; Lambrecht, R.M.

    1984-04-10

    A process is described for reliably and consistently producing astatine-211 in small controlled volumes of a solution, which is selected from a choice of solvents that are useful in selected radiopharmaceutical procedures in which the At-211 activities are to be applied. 4 figures, 1 table.

  16. Harvard-MIT research program in short-lived radiopharmaceuticals

    SciTech Connect

    Adelstein, S.J.

    1991-01-01

    This report presents research on radiopharmaceuticals. The following topics are discussed: antibody labeling with positron-emitting radionuclides; antibody modification for radioimmune imaging; labeling antibodies; evaluation of technetium acetlyacetonates as potential cerebral blood flow agents; and studies in technetium chemistry. (CBS)

  17. Radioisotope requirements and usage in the radiopharmaceutical industry

    SciTech Connect

    Langton, M.A.

    1995-12-31

    Radioisotopes are used extensively in many different productive and beneficial human endeavors. Amersham International, a U.K.-based company originating in the British Scientific Civil Service during World War II, has been actively involved in many of these activities for more than 50 yr. Today they are one of the world`s largest suppliers of radioactive compounds and scaled radiation sources for use in industrial quality and safety assurance, life science research, and medicine. This paper outlines one of these applications: the use of radioisotopes as radiopharmaceuticals. Radiopharmaceuticals are radioactive nuclides and labeled compounds that have been developed for the diagnosis and treatment of (human) disease. They are manufactured via highly controlled processes and have gone through regulatory scrutiny and approval far in excess of other radioisotopes used in other applications. Radiopharmaceuticals can be conveniently split into two categories. One type is simply an active analog that mimics the physiological behavior of its inactive counterpart in the body. The other involves an actual pharmacological compound that exhibits the desired physiological behavior, which is then labeled with a radionuclide suitable for either imaging or the delivery of a therapeutic radiation dose as appropriate but which plays no part in the mechanism of action of the drug. The latter type, which is the more common of the two, can be supplied either as an active compounded product or as a {open_quotes}cold kit,{close_quotes} which is then labeled with the appropriate radiopharmaceutical-grade radionuclide to yield the final product.

  18. Process for producing astatine-211 for radiopharmaceutical use

    DOEpatents

    Mirzadeh, Saed; Lambrecht, Richard M.

    1987-01-01

    A process for reliably and consistently producing astatine-211 in small controlled volumes of a solution, which is selected from a choice of solvents that are useful in selected radiopharmaceutical procedures in which the At-211 activities are to be applied.

  19. A simple liquid detector for radiopharmaceutical processing systems

    SciTech Connect

    Alexoff, D.L.; Hallaba, K.; Schlyer, D.; Ferrieri, R.

    1995-03-01

    Sensing the presence of liquids in tubing and vessels in radiochemical processing equipment provides information important to the remote or automatic control of the production of clinical doses of radiopharmaceuticals. Although modern commercial automated radiopharmaceutical synthesis machines do not usually include liquid presence as a measured process variable, earlier more complex automated synthesis devices did; and the inclusion of such feedback can increase system reliability and simplify trouble-shooting tasks carried out by computer software or human operators. Commercial liquid level detectors are often designed for large-scale industrial processes and are therefore too large or expensive to be useful in many radiochemical hardware systems. An inexpensive miniature optical liquid detector originally by Kramer and Fuchs has been duplicated here for use in monitoring the presence of liquids in teflon tubing (1/16 in. O.D.) in an enriched oxygen-18 water recovery system.

  20. Freeware for reporting radiation dosimetry following the administration of radiopharmaceuticals.

    PubMed

    Gómez Perales, Jesús Luis; García Mendoza, Antonio

    2015-09-01

    This work describes the development of a software application for reporting patient radiation dosimetry following radiopharmaceutical administration. The resulting report may be included within the patient's medical records. The application was developed in the Visual Basic programming language. The dosimetric calculations are based on the values given by the International Commission on Radiological Protection (ICRP). The software is available in both Spanish and English and can be downloaded at no cost from www.radiopharmacy.net. PMID:26092354

  1. Advancement in treatment and diagnosis of pancreatic cancer with radiopharmaceuticals

    PubMed Central

    Xu, Yu-Ping; Yang, Min

    2016-01-01

    Pancreatic cancer (PC) is a major health problem. Conventional imaging modalities show limited accuracy for reliable assessment of the tumor. Recent researches suggest that molecular imaging techniques with tracers provide more biologically relevant information and are benefit for the diagnosis of the cancer. In addition, radiopharmaceuticals also play more important roles in treatment of the disease. This review summaries the advancement of the radiolabeled compounds in the theranostics of PC. PMID:26909131

  2. Improving radiopharmaceutical supply chain safety by implementing bar code technology.

    PubMed

    Matanza, David; Hallouard, François; Rioufol, Catherine; Fessi, Hatem; Fraysse, Marc

    2014-11-01

    The aim of this study was to describe and evaluate an approach for improving radiopharmaceutical supply chain safety by implementing bar code technology. We first evaluated the current situation of our radiopharmaceutical supply chain and, by means of the ALARM protocol, analysed two dispensing errors that occurred in our department. Thereafter, we implemented a bar code system to secure selected key stages of the radiopharmaceutical supply chain. Finally, we evaluated the cost of this implementation, from overtime, to overheads, to additional radiation exposure to workers. An analysis of the events that occurred revealed a lack of identification of prepared or dispensed drugs. Moreover, the evaluation of the current radiopharmaceutical supply chain showed that the dispensation and injection steps needed to be further secured. The bar code system was used to reinforce product identification at three selected key stages: at usable stock entry; at preparation-dispensation; and during administration, allowing to check conformity between the labelling of the delivered product (identity and activity) and the prescription. The extra time needed for all these steps had no impact on the number and successful conduct of examinations. The investment cost was reduced (2600 euros for new material and 30 euros a year for additional supplies) because of pre-existing computing equipment. With regard to the radiation exposure to workers there was an insignificant overexposure for hands with this new organization because of the labelling and scanning processes of radiolabelled preparation vials. Implementation of bar code technology is now an essential part of a global securing approach towards optimum patient management. PMID:25144560

  3. [Computer simulated images of radiopharmaceutical distributions in anthropomorphic phantoms

    SciTech Connect

    Not Available

    1991-05-17

    We have constructed an anatomically correct human geometry, which can be used to store radioisotope concentrations in 51 various internal organs. Each organ is associated with an index number which references to its attenuating characteristics (composition and density). The initial development of Computer Simulated Images of Radiopharmaceuticals in Anthropomorphic Phantoms (CSIRDAP) over the first 3 years has been very successful. All components of the simulation have been coded, made operational and debugged.

  4. ( sup 111 In-DTPA-D-Phe sup 1 )-octreotide, a potential radiopharmaceutical for imaging of somatostatin receptor-positive tumors: Synthesis, radiolabeling and in vitro validation

    SciTech Connect

    Bakker, W.H.; Albert, R.; Bruns, C.; Breeman, W.A.P.; Hofland, L.J.; Marbach, P.; Pless, J.; Pralet, D.; Stolz, B.; Koper, J.W.; Lamberts, S.W.J.; Visser, T.J.; Krenning, E.P. Sandoz Pharma AG, Basel )

    1991-01-01

    As starting material for a potentially convenient radiopharmaceutical, a diethylenetriaminopentaacetic acid (DTPA) conjugated derivative of octreotide (SMS 201-995) was prepared. This peptide, (DTPA-D-Phe{sup 1})-octreotide (SDZ 215-811) binds more than 95% of added {sup 111}In in an easy, single-step labeling procedure without necessity of further purification. The specific somatostatin-like biologic effect of these analogues was proven by the inhibition of growth hormone secretion by cultured rat pituitary cells in a dose-dependent fashion by octreotide, (DTPA-D-Phe{sup 1})-octreotide and non-radioactive ({sup 115}In-DTPA-D-Phe{sup 1})-octreotide. The binding of ({sup 111}In-DTPA-D-Phe{sup 1})-octreotide to rat brain cortex membranes proved to be displaced similarly by natural somatosatin as well as by octreotide, suggesting specific binding of ({sup 111}In-DTPA-D-Phe{sup 1})-octreotide to somatostatin receptors. The binding of the indium-labeled compound showed a somewhat lower affinity when compared with the iodinated (Tyr{sup 3})-octreotide, but indium-labeled (DTPA-D-Phe{sup 1})-octreotide still binds with nanomolar affinity. In conjunction with in vivo studies, these results suggest that ({sup 111}In-DTPA-D-Phe{sup 1})-octreotide is a promising radiopharmaceutical for scintigraphic imaging of somatostatin receptor-positive tumors.

  5. Peptide Based Radiopharmaceuticals: Specific Construct Approach

    SciTech Connect

    Som, P; Rhodes, B A; Sharma, S S

    1997-10-21

    The objective of this project was to develop receptor based peptides for diagnostic imaging and therapy. A series of peptides related to cell adhesion molecules (CAM) and immune regulation were designed for radiolabeling with 99mTc and evaluated in animal models as potential diagnostic imaging agents for various disease conditions such as thrombus (clot), acute kidney failure, and inflection/inflammation imaging. The peptides for this project were designed by the industrial partner, Palatin Technologies, (formerly Rhomed, Inc.) using various peptide design approaches including a newly developed rational computer assisted drug design (CADD) approach termed MIDAS (Metal ion Induced Distinctive Array of Structures). In this approach, the biological function domain and the 99mTc complexing domain are fused together so that structurally these domains are indistinguishable. This approach allows construction of conformationally rigid metallo-peptide molecules (similar to cyclic peptides) that are metabolically stable in-vivo. All the newly designed peptides were screened in various in vitro receptor binding and functional assays to identify a lead compound. The lead compounds were formulated in a one-step 99mTc labeling kit form which were studied by BNL for detailed in-vivo imaging using various animals models of human disease. Two main peptides usingMIDAS approach evolved and were investigated: RGD peptide for acute renal failure and an immunomodulatory peptide derived from tuftsin (RMT-1) for infection/inflammation imaging. Various RGD based metallopeptides were designed, synthesized and assayed for their efficacy in inhibiting ADP-induced human platelet aggregation. Most of these peptides displayed biological activity in the 1-100 µM range. Based on previous work by others, RGD-I and RGD-II were evaluated in animal models of acute renal failure. These earlier studies showed that after acute ischemic injury the renal cortex displays

  6. Molecular Engineering of Technetium and Rhenium Based Radiopharmaceuticals

    SciTech Connect

    Zubieta, J.

    2003-06-30

    The research was based on the observation that despite the extraordinarily rich coordination chemistry of technetium and rhenium and several notable successes in reagent design, the extensive investigations by numerous research groups on a variety of N{sub 2}S{sub 2} and N{sub 3}S donor type ligands and on HYNIC have revealed that the chemistries of these ligands with Tc and Re are rather complex, giving rise to considerable difficulties in the development of reliable procedures for the development of radiopharmaceutical reagents.

  7. Silver-coated monolithic columns for separation in radiopharmaceutical applications.

    PubMed

    Sedlacek, Ondrej; Kucka, Jan; Svec, Frantisek; Hruby, Martin

    2014-04-01

    In this study, we demonstrate the preparation of a macroporous monolithic column containing anchored silver nanoparticles and its use for the elimination of excess radioiodine from the radiolabeled pharmaceutical. The poly(glycidyl methacrylate-co-ethylene dimethacrylate) monolith was first functionalized with cystamine and the free thiol groups liberated by reaction with borohydride. In-house-prepared silver nanoparticles were then attached by interaction with the surface thiols. The deiodization process was demonstrated with the commonly used radiopharmaceutical m-iodobenzylguanidine labeled with radionuclide iodine-125. PMID:24478196

  8. Dose Assessments to the Hands of Radiopharmaceutical Workers

    SciTech Connect

    Ilas, Dan; Eckerman, Keith F; Sherbini, Sami; Karagiannis, Harriet

    2008-01-01

    This paper describes the characterization of radiation doses to the hands of nuclear medicine technicians resulting from the handling of radiopharmaceuticals. Radiation monitoring using ring dosimeters indicates that finger dosimeters may overestimate or underestimate the radiation doses to the skin that are used to show compliance with applicable regulations depending on the nature of the particular procedure and the radioisotope being handled. To better understand the parameters governing the absorbed dose distributions, a detailed model of the hands was created and used in Monte Carlo simulations of selected nuclear medicine procedures. Simulations on realistic configurations typical for workers handling radiopharmaceuticals were performed for a range of energies of the source photons. The lack of charged-particle equilibrium necessitated full photon-electron coupled transport calculations. The results show that the dose to different regions of the fingers can differ substantially from the dosimeters' readings when the dosimeters are located at the base of the finger. We tried to identify consistent patterns that relate the actual dose to the dosimeter readings. These patterns depend on the specific work conditions and can be used to better assess the absorbed dose to different regions of the exposed skin.

  9. Nuclear medicine and imaging research (quantitative studies in radiopharmaceutical science)

    SciTech Connect

    Cooper, M.D.; Beck, R.N.

    1990-09-01

    This is a report of progress in Year Two (January 1, 1990--December 31, 1990) of Grant FG02-86ER60438, Quantitative Studies in Radiopharmaceutical Science,'' awarded for the three-year period January 1, 1989--December 31, 1991 as a competitive renewal following site visit in the fall of 1988. This program addresses the problems involving the basic science and technology underlying the physical and conceptual tools of radioactive tracer methodology as they relate to the measurement of structural and functional parameters of physiologic importance in health and disease. The principal tool is quantitative radionuclide imaging. The overall objective of this program is to further the development and transfer of radiotracer methodology from basic theory to routine clinical practice in order that individual patients and society as a whole will receive the maximum net benefit from the new knowledge gained. The focus of the research is on the development of new instruments and radiopharmaceuticals, and the evaluation of these through the phase of clinical feasibility. 25 refs., 13 figs., 1 tab.

  10. Process for producing astatine-211 for radiopharmaceutical use

    SciTech Connect

    Mirzadeh, S.; Lambrecht, R.M.

    1987-07-21

    A one-step chemical manipulation is described in combination with a distillation and collection process for producing At-211 comprising; a. providing a target of irradiated Bismuth coated to a predetermined thickness of a backing member, b. providing a vapor-producing still operably connected with a condenser that has a water cooled condensate collector formed of a dry silica gel mesh maintained at a temperature above the freezing point of water, and providing an effluent gas filter that is operably connected to receive effluent gas from the condenser, c. heating the target in the still at a temperature in the range of about 630/sup 0/-680/sup 0/C for a time period in the range of 50 to 80 minutes, to evole At-211 vapor from the target, c. providing a dry carrier gas having an oxygen concentration that is sufficient to form Bi/sub 2/O/sub 3/ thereby to essentially preclude vaporization of Bi metal, passing the carrier gas through the still to carry the At-211 vapor to the condenser, and to carry effluent from the condenser to the effluent gas filter, e. eluting At-211 from the condensate collector of the condenser with a controlled volume of eluent containing predetermined solvents that are compatible with a given desired radiopharmaceutical procedure, and f. collecting the At-211 in the controlled volume of eluent for use in the given radiopharmaceutical procedure.

  11. Cyclotron targets and production technologies used for radiopharmaceuticals in NPI

    NASA Astrophysics Data System (ADS)

    Fišer, M.; Kopička, K.; Hradilek, P.; Hanč, P.; Lebeda, O.; Pánek, J.; Vognar, M.

    2003-01-01

    This paper deals with some technical aspects of the development and production of cyclotronmade radiopharmaceuticals (excluding PET). In this field, nuclear chemistry and pharmacy are in a close contact; therefore, requirements of the both should be taken into account. The principles of cyclotron targetry, separation/recovery of materials and synthesis of active substances are given, as well as issues connected with formulation of pharmaceutical forms. As the radiopharmaceuticals should fulfil the requirements on in vivo preparations, there exist a variety of demands pertaining to Good Manufacturing Practice (GMP) concept, which is also briefly discussed. A typical production chain is presented and practical examples of real technologies based on cyclotron-made radionuclides are given as they have been used in Nuclear Physics Institute of CAS (NPI). Special attention is devoted to the technology of enriched cyclotron targets. Frequently used medicinal products employing cyclotron-produced active substances are characterised (Rb/Kr generators, 123I-labelled MIBG, OIH and MAB's). The cyclotron produced radioactive implants for transluminal coronary angioplasty (radioactive stents) are introduced as an example of a medical device developed for therapeutic application.

  12. New selenium-75 labeled radiopharmaceuticals: selenonium analogues of dopamine

    SciTech Connect

    Sadek, S.A.; Basmadjian, G.P.; Hsu, P.M.; Rieger, J.A.

    1983-07-01

    Selenium-75 labeled selenonium analogues of dopamine, (2-(3,4-dimethoxyphenyl)ethyl)dimethylselenonium iodide and its dihydroxy analogue, were prepared by reducing (/sup 75/Se)selenious acid with sodium borohydride at pH 6.0 and reacting the NaSeH produced with 1-(3,4-dimethoxyphenyl)-2-(p-toluenesulfonyloxy)ethane. Tissue distribution studies in rats given the /sup 75/Se-labeled selenonium agents intravenously demonstrated high initial heart uptake. Prolonged adrenal retention and high adrenal to blood ratio of compound 4 were observed. The high uptake and adrenal to blood ratio suggest the potential use of compound 4 as a radiopharmaceutical for the adrenal gland.

  13. Deterioration of stannous ion in radiopharmaceutical kits during storage.

    PubMed

    McBride, M H; Shaw, S M; Kessler, W V

    1979-10-01

    The deterioration of stannous ion (Sn++) in inhouse-prepared and commercial radiopharmaceutical kits was studied. Sn++ content of three types of nonlyophilized, deoxygenated, aqueous inhouse-prepared kits [diethylenetriamine pentaacetic acid (DTPA), pyrophosphate and glucoheptonate] and of three commercially prepared kits (two lyophilized pyrophosphate kits and one diphosphonate in sealed glass ampul kit) was measured by differential pulse polarography. Inhouse-prepared kits were assayed initially and after storage for 6, 12, 24 and 48 days at 24, 5 and -18 C. Commercial kits were assayed initially and after storage for 12, 24 and 48 days at 5 and 24 C. Of the inhouse-prepared kits, Sn++ stability when stored for 48 days at 5 and 24 C. Freezer storage should be used, when possible, to insure maximum stability of Sn++ in inhouse-prepared, nonlyophilized ratiopharmaceutical kits. The commercial procedures of lyophilization and of sealing the reagent in a sealed glass ampul prolong Sn++ stability. PMID:507080

  14. Relative biological effectiveness of 99mTc radiopharmaceuticals.

    PubMed

    Narra, V R; Sastry, K S; Goddu, S M; Howell, R W; Strand, S E; Rao, D V

    1994-12-01

    The radiotoxicity of three 99mTc-labeled compounds is investigated using spermatogenesis in mouse testis as the experimental model, and spermatogonial cell survival as the biological end point. The radiopharmaceuticals studied are pertechnetate (99mTcO4-), pyrophosphate (99mTc-PYP), and hydroxyethylene diphosphate (99mTc-HDP). The mean lethal doses at 37% survival (D37) are 0.70 +/- 0.06, 0.84 +/- 0.13, and 0.59 +/- 0.08 Gy for 99mTcO4-, 99mTc-PYP, and 99mTc-HDP, respectively. When these results are compared with the D37 value obtained with external x rays or internal gamma rays, the relative biological effectiveness (RBE) of these compounds are 0.94 +/- 0.09, 0.79 +/- 0.13, and 1.1 +/- 0.16, respectively. These results show that the radiotoxicity of 99mTc in mouse testis is essentially similar to that of low-LET radiations (i.e., RBE approximately 1). To understand these results, the distribution of these radiocompounds in the testis is determined and correlated with the observed RBE values. The expected range of RBE values for 99mTc radiopharmaceuticals in organs is 0.95 to 1.5, depending on the fraction of organ activity that is bound to DNA. This suggests that the Auger electrons emitted in the decay of 99mTc are not capable of causing extreme toxicity in vivo. These results provide further support for 99mTc as the radionuclide of choice for imaging in nuclear medicine. PMID:7700199

  15. A rapid and efficient preparation of [123I]radiopharmaceuticals using a small HPLC (Rocket) column.

    PubMed

    Katsifis, Andrew; Papazian, Vahan; Jackson, Timothy; Loc'h, Christian

    2006-01-01

    A simplified method for the rapid and efficient preparation of [(123)I]radiopharmaceuticals is described. Three radiopharmaceuticals, [(123)I]beta-CIT, [(123)I]MIBG and [(123)I]clioquinol, were synthesised and purified as model compounds. The radiotracers were labelled with iodine-123 using electrophilic oxidative conditions and purified by a compact semi-preparative reverse phase column (C-18, 3 microm, 7 x 53 mm, Alltima Rocket, Alltech) using aqueous-ethanol as HPLC solvents that were directly used for radiopharmaceutical formulation. The radiochemical purity of the radioiodinated tracers as assessed by analytical HPLC was higher than 99% with specific activity higher than 3 GBq/nmol. The total preparation time of a radiotracer ranged from 40 to 60 min and, starting from 3.7 GBq of iodine-123, more than 2.5 GBq of formulated radiopharmaceuticals were available for clinical investigations. PMID:16129607

  16. USE OF RADIOPHARMACEUTICALS IN DIAGNOSTIC NUCLEAR MEDICINE IN THE UNITED STATES: 1960–2010

    PubMed Central

    Drozdovitch, Vladimir; Brill, Aaron B.; Callahan, Ronald J.; Clanton, Jeffrey A.; DePietro, Allegra; Goldsmith, Stanley J.; Greenspan, Bennett S.; Gross, Milton D.; Hays, Marguerite T.; Moore, Stephen C.; Ponto, James A.; Shreeve, Walton W.; Melo, Dunstana R.; Linet, Martha S.; Simon, Steven L.

    2014-01-01

    To reconstruct reliable nuclear medicine-related occupational radiation doses or doses received as patients from radiopharmaceuticals over the last five decades, we assessed which radiopharmaceuticals were used in different time periods, their relative frequency of use, and typical values of the administered activity. This paper presents data on the changing patterns of clinical use of radiopharmaceuticals and documents the range of activity administered to adult patients undergoing diagnostic nuclear medicine procedures in the U.S. between 1960 and 2010. Data are presented for 15 diagnostic imaging procedures that include thyroid scan and thyroid uptake, brain scan, brain blood flow, lung perfusion and ventilation, bone, liver, hepatobiliary, bone marrow, pancreas, and kidney scans, cardiac imaging procedures, tumor localization studies, localization of gastrointestinal bleeding, and non-imaging studies of blood volume and iron metabolism. Data on the relative use of radiopharmaceuticals were collected using key informant interviews and comprehensive literature reviews of typical administered activities of these diagnostic nuclear medicine studies. Responses of key informants on relative use of radiopharmaceuticals are in agreement with published literature. Results of this study will be used for retrospective reconstruction of occupational and personal medical radiation doses from diagnostic radiopharmaceuticals to members of the U.S. radiologic technologist’s cohort and in reconstructing radiation doses from occupational or patient radiation exposures to other U.S. workers or patient populations. PMID:25811150

  17. Synthesis and biological studies of positron-emitting radiopharmaceuticals

    SciTech Connect

    Dischino, D.D.

    1983-01-01

    The development and clinical evaluation of two-positron emitting radiopharmaceuticals designed to image myelin in humans is reported. Carbon-11-labeled benzyl methyl ether was synthesized by the reaction of carbon-11-labeled methanol and benzyl chloride in dimethyl sulfoxide containing powdered potassium hydroxide in a radiochemical yield of 43% and a synthesis and purification time of 40 minutes. Carbon-11-labeled diphenylmethanol was synthesized by the reaction of carbon-11-labeled carbon dioxide and phenyllithium followed by the reduction of the carbon-11-labeled intermediate to diphenylmethanol via lithium aluminum hydride in a radiochemical yield of 71% and a synthesis and purification time of 38 minutes. Carbon-11-labeled benzyl methyl ether and diphenylmethanol were each evaluated as myelin imaging agents in three patients with multiple sclerosis via positron-emission tomography. In two out of three patients studied with carbon-11-labeled benzyl methyl ether, the distribution of activity in the brain was not consistent with local lipid content. A new synthesis of carbon-11-labeled-DL-phenylalanine labeled in the benzylic position and the synthesis of fluorine-18-labeled 1-(2-nitro-1-imidazolyl)-3-fluoro-2-propanol, a potential in vivo marker of hypoxic tissue, are reported.

  18. AUTOMATION FOR THE SYNTHESIS AND APPLICATION OF PET RADIOPHARMACEUTICALS.

    SciTech Connect

    Alexoff, D.L.

    2001-09-21

    The development of automated systems supporting the production and application of PET radiopharmaceuticals has been an important focus of researchers since the first successes of using carbon-11 (Comar et al., 1979) and fluorine-18 (Reivich et al., 1979) labeled compounds to visualize functional activity of the human brain. These initial successes of imaging the human brain soon led to applications in the human heart (Schelbert et al., 1980), and quickly radiochemists began to see the importance of automation to support PET studies in humans (Lambrecht, 1982; Langstrom et al., 1983). Driven by the necessity of controlling processes emanating high fluxes of 511 KeV photons, and by the tedium of repetitive syntheses for carrying out these human PET investigations, academic and government scientists have designed, developed and tested many useful and novel automated systems in the past twenty years. These systems, originally designed primarily by radiochemists, not only carry out effectively the tasks they were designed for, but also demonstrate significant engineering innovation in the field of laboratory automation.

  19. The Next Generation of Positron Emission Tomography Radiopharmaceuticals in Oncology

    PubMed Central

    Rice, Samuel L.; Roney, Celeste A.; Daumar, Pierre; Lewis, Jason S.

    2015-01-01

    Although 18F-fluorodeoxyglucose (18F-FDG) is still the most widely used positron emission tomography (PET) radiotracer, there are a few well-known limitations to its use. The last decade has seen the development of new PET probes for in vivo visualization of specific molecular targets, along with important technical advances in the production of positron-emitting radionuclides and their related labeling methods. As such, a broad range of new PET tracers are in preclinical development or have recently entered clinical trials. The topics covered in this review include labeling methods, biological targets, and the most recent preclinical or clinical data of some of the next generation of PET radiopharmaceuticals. This review, which is by no means exhaustive, has been separated into sections related to the PET radionuclide used for radiolabeling: fluorine-18, for the labeling of agents such as FACBC, FDHT, choline, and Galacto-RGD; carbon-11, for the labeling of choline; gallium-68, for the labeling of peptides such as DOTATOC and bombesin analogs; and the long-lived radionuclides iodine-124 and zirconium-89 for the labeling of monoclonal antibodies cG250, and J591 and trastuzumab, respectively. PMID:21624561

  20. New SPECT and PET Radiopharmaceuticals for Imaging Cardiovascular Disease

    PubMed Central

    Sogbein, Oyebola O.; Pelletier-Galarneau, Matthieu; Schindler, Thomas H.; Wei, Lihui; Wells, R. Glenn; Ruddy, Terrence D.

    2014-01-01

    Nuclear cardiology has experienced exponential growth within the past four decades with converging capacity to diagnose and influence management of a variety of cardiovascular diseases. Single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) with technetium-99m radiotracers or thallium-201 has dominated the field; however new hardware and software designs that optimize image quality with reduced radiation exposure are fuelling a resurgence of interest at the preclinical and clinical levels to expand beyond MPI. Other imaging modalities including positron emission tomography (PET) and magnetic resonance imaging (MRI) continue to emerge as powerful players with an expanded capacity to diagnose a variety of cardiac conditions. At the forefront of this resurgence is the development of novel target vectors based on an enhanced understanding of the underlying pathophysiological process in the subcellular domain. Molecular imaging with novel radiopharmaceuticals engineered to target a specific subcellular process has the capacity to improve diagnostic accuracy and deliver enhanced prognostic information to alter management. This paper, while not comprehensive, will review the recent advancements in radiotracer development for SPECT and PET MPI, autonomic dysfunction, apoptosis, atherosclerotic plaques, metabolism, and viability. The relevant radiochemistry and preclinical and clinical development in addition to molecular imaging with emerging modalities such as cardiac MRI and PET-MR will be discussed. PMID:24901002

  1. PET - radiopharmaceutical facilities at Washington University Medical School - an overview

    SciTech Connect

    Dence, C.S.; Welch, M.J.

    1994-12-31

    The PET program at Washington University has evolved over more than three decades of research and development in the use of positron-emitting isotopes in medicine and biology. In 1962 the installation of the first hospital cyclotron in the USA was accomplished. This first machine was an Allis Chalmers (AC) cyclotron and it was operated until July, 1990. Simultaneously with this cyclotron the authors also ran a Cyclotron Corporation (TCC) CS-15 cyclotron that was purchased in 1977. Both of these cyclotrons were maintained in-house and operated with a relatively small downtime (approximately 3.5%). After the dismantling of the AC machine in 1990, a Japanese Steel Works 16/8 (JSW-16/8) cyclotron was installed in the vault. Whereas the AC cyclotron could only accelerate deuterons (6.2 MeV), the JSW - 16/8 machine can accelerate both protons and deuterons, so all of the radiopharmaceuticals can be produced on either of the two presently owned accelerators. At the end of May 1993, the medical school installed the first clinical Tandem Cascade Accelerator (TCA) a collaboration with Science Research Laboratories (SRL) of Somerville, MA. Preliminary target testing, design and development are presently under way. In 1973, the University installed the first operational PETT device in the country, and at present there is a large basic science and clinical research program involving more than a hundred staff in nuclear medicine, radiation sciences, neurology, neurosurgery, psychiatry, cardiology, pulmonary medicine, oncology, and surgery.

  2. Environmental effects on the structure of metal ion-DOTA complexes: An ab initio study of radiopharmaceutical metals.

    SciTech Connect

    Lau, E Y; Lightstone, F C; Colvin, M E

    2006-02-10

    Quantum mechanical calculations were performed to study the differences between the important radiopharmaceutical metals yttrium (Y) and indium (In) bound by DOTA and modified DOTA molecules. Energies were calculated at the MP2/6-31+G(d)//HF/6-31G(d) levels, using effective core potentials on the Y and In ions. Although the minimum energy structures obtained are similar for both metal ion-DOTA complexes, changes in coordination and local environment significantly affect the geometries and energies of these complexes. Coordination by a single water molecule causes a change in the coordination number and a change in the position of the metal ion in In-DOTA; but, Y-DOTA is hardly affected by water coordination. When one of the DOTA carboxylates is replaced by an amide, the coordination energy for the amide arm shows a large variation between the Y and In ions. Optimizations including water and guandinium moieties to approximate the effects of antibody binding indicate a large energy cost for the DOTA-chelated In to adopt the ideal conformation for antibody binding.

  3. In Vitro Assessment of the In Vivo Stability of Cu-64 Radiopharmaceuticals

    SciTech Connect

    Packard, Alan B

    2011-12-15

    Research Plans: The successful development of Cu-64 radiopharmaceuticals depends upon retention of the Cu-64 atom in the radiopharmaceutical. To date, the focus has been on the development of chelators that better retain Cu-64, but there has been no effort to develop an effective method by which improved retention may be measured. In the absence of a suitable analytical method, the stability of Cu-64 radiopharmaceuticals is estimated indirectly, with decreased liver uptake suggesting higher in vivo complex stability. But this approach is inadequate for radiopharmaceuticals, such as radiolabeled antibodies, that are expected to accumulate in the liver even when there is no free Cu-64 present. The absence of such a method has also hampered efforts to systematically evaluate the chemical factors that may give rise to improved retention. The objective of this project is to develop and validate such a method. Accomplishments: The two primary accomplishments of this project will be 1) the development and validation of a method to measure the stability of Cu-64 radiopharmaceuticals and 2) the determination of the chemical factors that define the in vivo stability of Cu 64 radiopharmaceuticals. Because Cu(II) is extremely labile, the in vivo stability of Cu-64 radiopharmaceuticals is not primarily determined by the amount of free Cu that is present at any given time or by the thermodynamic stability constants, but rather by the rate at which Cu is lost from the complex, the dissociation rate constant, kd. The dissociation rate constants of the Cu-64 complexes from a series of bifunctional chelators (BFCs) will be measured using Free Ion Selective Radiotracer Extraction (FISRE), a technique originally developed to measure bioavailable Cu in environmental samples. FISRE will also be applied to the determination of the kd's of a series of reference Cu-64 complexes to determine the chemical factors that define the in vivo stability of Cu-64 radiopharmaceuticals. Potential

  4. Intelligent portal monitor for fast suppression of false positives due to radiopharmaceuticals

    SciTech Connect

    Johnson, M.W.; Butterfield, K.B.

    1985-01-01

    Monitoring the movement of radioactive material through secure or sensitive areas may be complicated by the existence of unanticipated sources of radiation carried by individuals passing through the area. Typical of such sources are radiopharmaceuticals prescribed for a medical procedure. We report here on an apparatus designed to quickly discriminate between in-vivo radiopharmaceuticals and other nuclear materials, based on a pattern-recognition algorithm and a microcomputer. Principles of operation are discussed, and the data base for the pattern-recognition algorithm is displayed. Operating experience with the apparatus in a trial location is also discussed. Our apparatus correctly identifies in-vivo radiopharmaceuticals in over 80% of all trials; challenges with radioisotopes other than radiopharmaceuticals have led the apparatus, without exception, to reject the challenge isotope as incompatible with medical practice. The apparatus thus rapidly discriminates between individuals bearing radiopharmaceuticals and those bearing illicit sources, such as special nuclear materials. Examples of applications are presented. 7 refs., 4 figs., 1 tab.

  5. Hepatic extraction fraction of hepatobiliary radiopharmaceuticals measured using spectral analysis.

    PubMed

    Murase, K; Tsuda, T; Mochizuki, T; Ikezoe, J

    1999-11-01

    Measuring the hepatic extraction fraction (HEF) of a hepatobiliary radiopharmaceutical helps to differentiate hepatocyte from biliary tract diseases, and it is generally performed using deconvolution analysis. In this study, we measured HEF using spectral analysis. With spectral analysis, HEF was calculated from (the sum of the spectral data obtained by spectral analysis--the highest frequency component of the spectrum) divided by (the sum of the spectral data) x 100 (%). We applied this method to dynamic liver scintigraphic data obtained from six healthy volunteers and from 46 patients with various liver diseases, using 99Tcm-N-pyridoxyl-5-methyltryptophan (PMT). We also measured HEF using deconvolution analysis, in which the modified Fourier transform technique was employed. The HEF values obtained by spectral analysis correlated closely with those obtained by deconvolution analysis (r = 0.925), suggesting our method is valid. The HEF values obtained by spectral analysis decreased as the severity of liver disease progressed. The values were 100.0 +/- 0.0%, 94.7 +/- 13.6%, 76.2 +/- 27.4%, 45.7 +/- 15.6%, 82.7 +/- 24.2% and 95.2 +/- 11.8% (mean +/- S.D.) for the normal controls (n = 6), mild liver cirrhosis (n = 16), moderate liver cirrhosis (n = 11), severe liver cirrhosis (n = 5), acute hepatitis (n = 8) and chronic hepatitis groups (n = 6), respectively. The HEF was obtained more simply and rapidly by spectral analysis than by deconvolution analysis. The results suggest that our method using spectral analysis can be used as an alternative to the conventional procedure using deconvolution analysis for measuring HEF. PMID:10572914

  6. Radiopharmaceuticals for diagnosis. [Final] report, 1 January 1991--31 December 1993

    SciTech Connect

    Kuhl, D.E.

    1993-06-01

    Since 1987, this grant has supported the development of new radiochemical methods for use with short-lived, positron-emitting radionuclides; new laboratory techniques for radiochemical syntheses; and development of new radiopharmaceuticals which will be of use in Positron Emission Tomography. For the period 1 January 1991 to 31 December 1993, the authors have continued their efforts in all of these areas, as they feel that an integrated approach to the synthesis and characterization of new PET Radiopharmaceuticals is crucial to the continued growth and application of this imaging technique in modern medicine. Progress in a number of these areas is described in this report.

  7. Lutetium-177 DOTATATE Production with an Automated Radiopharmaceutical Synthesis System

    PubMed Central

    Aslani, Alireza; Snowdon, Graeme M; Bailey, Dale L; Schembri, Geoffrey P; Bailey, Elizabeth A; Pavlakis, Nick; Roach, Paul J

    2015-01-01

    Objective(s): Peptide Receptor Radionuclide Therapy (PRRT) with yttrium-90 (90Y) and lutetium-177 (177Lu)-labelled SST analogues are now therapy option for patients who have failed to respond to conventional medical therapy. In-house production with automated PRRT synthesis systems have clear advantages over manual methods resulting in increasing use in hospital-based radiopharmacies. We report on our one year experience with an automated radiopharmaceutical synthesis system. Methods: All syntheses were carried out using the Eckert & Ziegler Eurotope’s Modular-Lab Pharm Tracer® automated synthesis system. All materials and methods used were followed as instructed by the manufacturer of the system (Eckert & Ziegler Eurotope, Berlin, Germany). Sterile, GMP-certified, no-carrier added (NCA) 177Lu was used with GMP-certified peptide. An audit trail was also produced and saved by the system. The quality of the final product was assessed after each synthesis by ITLC-SG and HPLC methods. Results: A total of 17 [177Lu]-DOTATATE syntheses were performed between August 2013 and December 2014. The amount of radioactive [177Lu]-DOTATATE produced by each synthesis varied between 10-40 GBq and was dependant on the number of patients being treated on a given day. Thirteen individuals received a total of 37 individual treatment administrations in this period. There were no issues and failures with the system or the synthesis cassettes. The average radiochemical purity as determined by ITLC was above 99% (99.8 ± 0.05%) and the average radiochemical purity as determined by HPLC technique was above 97% (97.3 ± 1.5%) for this period. Conclusions: The automated synthesis of [177Lu]-DOTATATE using Eckert & Ziegler Eurotope’s Modular-Lab Pharm Tracer® system is a robust, convenient and high yield approach to the radiolabelling of DOTATATE peptide benefiting from the use of NCA 177Lu and almost negligible radiation exposure of the operators. PMID:27408890

  8. Auger Radiopharmaceutical Therapy Targeting Prostate-Specific Membrane Antigen

    PubMed Central

    Kiess, Ana P.; Hobbs, Robert; Sgouros, George; Mease, Ronnie C.; Pullambhatla, Mrudula; Shen, Colette J.; Foss, Catherine A.; Pomper, Martin G.

    2015-01-01

    Auger electron emitters such as 125I have a high linear energy transfer and short range of emission (<10 μm), making them suitable for treating micrometastases while sparing normal tissues. We used a highly specific small molecule targeting the prostate-specific membrane antigen (PSMA) to deliver 125I to prostate cancer cells. Methods The PSMA-targeting Auger emitter 2-[3-[1-carboxy-5-(4-125I-iodo-benzoylamino)-pentyl]-ureido]-pentanedioic acid (125I-DCIBzL) was synthesized. DNA damage (via phosphorylated H2A histone family member X staining) and clonogenic survival were tested in PSMA-positive (PSMA+) PC3 PIP and PSMA-negative (PSMA−) PC3 flu human prostate cancer cells after treatment with 125I-DCIBzL. Subcellular drug distribution was assessed with confocal microscopy using a related fluorescent PSMA-targeting compound YC-36. In vivo antitumor efficacy was tested in nude mice bearing PSMA+ PC3 PIP or PSMA− PC3 flu flank xenografts. Animals were administered (intravenously) 111 MBq (3 mCi) of 125I-DCIBzL, 111 MBq (3 mCi) of 125I-NaI, an equivalent amount of nonradiolabeled DCIBzL, or saline. Results After treatment with 125I-DCIBzL, PSMA+ PC3 PIP cells exhibited increased DNA damage and decreased clonogenic survival when compared with PSMA− PC3 flu cells. Confocal microscopy of YC-36 showed drug distribution in the perinuclear area and plasma membrane. Animals bearing PSMA+ PC3 PIP tumors had significant tumor growth delay after treatment with 125I-DCIBzL, with only 1 mouse reaching 5 times the initial tumor volume by 60 d after treatment, compared with a median time to 5 times volume of less than 15 d for PSMA− PC3 flu tumors and all other treatment groups (P = 0.002 by log-rank test). Conclusion PSMA-targeted radiopharmaceutical therapy with the Auger emitter 125I-DCIBzL yielded highly specific antitumor efficacy in vivo, suggesting promise for treatment of prostate cancer micrometastases. PMID:26182968

  9. Systemic metabolic radiopharmaceutical therapy in the treatment of metastatic bone pain.

    PubMed

    Paes, Fabio M; Serafini, Aldo N

    2010-03-01

    Bone pain due to skeletal metastases constitutes the most common type of chronic pain among patients with cancer. It significantly decreases the patient's quality of life and is associated with comorbidities, such as hypercalcemia, pathologic fractures and spinal cord compression. Approximately 65% of patients with prostate or breast cancer and 35% of those with advanced lung, thyroid, and kidney cancers will have symptomatic skeletal metastases. The management of bone pain is extremely difficult and involves a multidisciplinary approach, which usually includes analgesics, hormone therapies, bisphosphonates, external beam radiation, and systemic radiopharmaceuticals. In patients with extensive osseous metastases, systemic radiopharmaceuticals should be the preferred adjunctive therapy for pain palliation. In this article, we review the current approved radiopharmaceutical armamentarium for bone pain palliation, focusing on indications, patient selection, efficacy, and different biochemical characteristics and toxicity of strontium-89 chloride, samarium-153 lexidronam, and rhenium-186 etidronate. A brief discussion on the available data on rhenium-188 is presented focusing on its major advantages and disadvantages. We also perform a concise appraisal of the other available treatment options, including pharmacologic and hormonal treatment modalities, external beam radiation, and bisphosphonates. Finally, the available data on combination therapy of radiopharmaceuticals with bisphosphonates or chemotherapy are discussed. PMID:20113678

  10. Design of CGMP Production of 18F- and 68Ga-Radiopharmaceuticals

    PubMed Central

    Chu, Pei-Chun; Chao, Hao-Yu; Shieh, Wei-Chen; Chen, Chuck C.

    2014-01-01

    Objective. Radiopharmaceutical production process must adhere to current good manufacturing process (CGMP) compliance to ensure the quality of precursor, prodrug (active pharmaceutical ingredient, API), and the final drug product that meet acceptance criteria. We aimed to develop an automated system for production of CGMP grade of PET radiopharmaceuticals. Methods. The hardware and software of the automated synthesizer that fit in the hot cell under cGMP requirement were developed. Examples of production yield and purity for 68Ga-DOTATATE and 18F-FDG at CGMP facility were optimized. Analytical assays and acceptance criteria for cGMP grade of 68Ga-DOTATATE and 18F-FDG were established. Results. CGMP facility for the production of PET radiopharmaceuticals has been established. Radio-TLC and HPLC analyses of 68Ga-DOTATATE and 18F-FDG showed that the radiochemical purity was 92% and 96%, respectively. The products were sterile and pyrogenic-free. Conclusion. CGMP compliance of radiopharmaceuticals has been reviewed. 68Ga-DOTATATE and 18F-FDG were synthesized with high radiochemical yield under CGMP process. PMID:25276810

  11. Harvard-MIT research program in short-lived radiopharmaceuticals. Technical progress report, 1991

    SciTech Connect

    Adelstein, S.J.

    1991-12-31

    This report presents research on radiopharmaceuticals. The following topics are discussed: antibody labeling with positron-emitting radionuclides; antibody modification for radioimmune imaging; labeling antibodies; evaluation of technetium acetlyacetonates as potential cerebral blood flow agents; and studies in technetium chemistry. (CBS)

  12. Pharmaceutical and clinical development of phosphonate-based radiopharmaceuticals for the targeted treatment of bone metastases.

    PubMed

    Lange, Rogier; Ter Heine, Rob; Knapp, Russ Ff; de Klerk, John M H; Bloemendal, Haiko J; Hendrikse, N Harry

    2016-10-01

    Therapeutic phosphonate-based radiopharmaceuticals radiolabeled with beta, alpha and conversion electron emitting radioisotopes have been investigated for the targeted treatment of painful bone metastases for >35years. We performed a systematic literature search and focused on the pharmaceutical development, preclinical research and early human studies of these radiopharmaceuticals. The characteristics of an ideal bone-targeting therapeutic radiopharmaceutical are presented and compliance with these criteria by the compounds discussed is verified. The importance of both composition and preparation conditions for the stability and biodistribution of several agents is discussed. Very few studies have described the characterization of these products, although knowledge on the molecular structure is important with respect to in vivo behavior. This review discusses a total of 91 phosphonate-based therapeutic radiopharmaceuticals, of which only six agents have progressed to clinical use. Extensive clinical studies have only been described for (186)Re-HEDP, (188)Re-HEDP and (153)Sm-EDTMP. Of these, (153)Sm-EDTMP represents the only compound with worldwide marketing authorization. (177)Lu-EDTMP has recently received approval for clinical use in India. This review illustrates that a thorough understanding of the radiochemistry of these agents is required to design simple and robust preparation and quality control methods, which are needed to fully exploit the potential benefits of these theranostic radiopharmaceuticals. Extensive biodistribution and dosimetry studies are indispensable to provide the portfolios that are required for assessment before human administration is possible. Use of the existing knowledge collected in this review should guide future research efforts and may lead to the approval of new promising agents. PMID:27496068

  13. Understanding radioxenon isotopical ratios originating from radiopharmaceutical facilities

    NASA Astrophysics Data System (ADS)

    Saey, P. R. J.; Ringbom, A.; Bowyer, T. W.; Becker, A.; de Geer, L.-E.; Nikkinen, M.; Payne, R. F.

    2009-04-01

    It was recently shown that radiopharmaceutical facilities (RPF) are major contributors to the general background of 133Xe and other xenon isotopes both in the northern and southern hemisphere. To distinguish a nuclear explosion signal from releases from civil nuclear facilities, not only the activity concentrations but also the ratios of the four different CTBT relevant radioxenon isotopes (131mXe, 133mXe, 133Xe and 135Xe) have to be well understood. First measurements taken recently in and around two of the world's largest RPF's: NTP at Pelindaba, South Africa and IRE at Fleurus, Belgium have been presented. At both sites, also stack samples were taken in close cooperation with the facility operators. The radioxenon in Belgium could be classified in four classes: the normal European background (133Xe activity between 0 - 5 mBq/m3) on one hand and then the samples where all four isotopes were detected with 133mXe/131mXe > 1. In northern South Africa the Pelindaba RPF is in practice the sole source of radioxenon. It generated a background of 133Xe at the measurement site some 230 km to the west of the RPF of 0 - 5 mBq/m3. In the cases where the air from the Pelindaba facility reached the measurement site directly and in a short time period, the 133Xe was higher, also 135Xe was present and in some samples 133mXe as well. The ratios of the activity concentrations of 135Xe/133Xe vs. 133mXe/131mXe (Multiple Isotope Ratio Plot - MIRC) have been analysed. For both facilities, the possible theoretical ratio's for different scenarios were calculated with the information available and compared with the measurements. It was found that there is an excess of 131mXe present in the European samples compared to theoretical calculations. A similar excess has also been seen in samples measured in northern America. In South Africa, neither the environmental samples nor the stack ones contained 131mXe at measurable levels. This can probably be explained by different processes and

  14. Joint CDRH (Center for Devices and Radiological Health) and state quality-assurance surveys in nuclear medicine: Phase 2 - radiopharmaceuticals

    SciTech Connect

    Hamilton, D.R.; Evans, C.D.

    1986-08-01

    The report discusses survey results on aspects of the quality assurance of radio-pharmaceuticals from 180 nuclear-medicine facilities in the United States. Data were collected from facilities in 8 states. Demographic information about nuclear-medicine operations and quality-assurance programs was gathered by state radiation-control-program personnel. The data collected from the survey show an incomplete acceptance of quality-assurance practices for radiopharmaceuticals. Most of the facilities in the survey indicated that, because an inferior radiopharmaceutical was prepared so infrequently, they did not believe it was cost-effective to perform extensive quality-assurance testing. The Center for Devices and Radiological Health hopes that the information from the survey will stimulate nuclear-medicine professionals and their organizations to encourage appropriate testing of all radiopharmaceuticals.

  15. Radiobiological Optimization of Combination Radiopharmaceutical Therapy Applied to Myeloablative Treatment of Non-Hodgkin’s Lymphoma

    PubMed Central

    Hobbs, Robert F; Wahl, Richard L; Frey, Eric C; Kasamon, Yvette; Song, Hong; Huang, Peng; Jones, Richard J; Sgouros, George

    2014-01-01

    Combination treatment is a hallmark of cancer therapy. Although the rationale for combination radiopharmaceutical therapy was described in the mid ‘90s, such treatment strategies have only been implemented clinically recently, and without a rigorous methodology for treatment optimization. Radiobiological and quantitative imaging-based dosimetry tools are now available that enable rational implementation of combined targeted radiopharmaceutical therapy. Optimal implementation should simultaneously account for radiobiological normal organ tolerance while optimizing the ratio of two different radiopharmaceuticals required to maximize tumor control. We have developed such a methodology and applied it to hypothetical myeloablative treatment of non-hodgkin’s lymphoma (NHL) patients using 131I-tositumomab and 90Y-ibritumomab tiuxetan. Methods The range of potential administered activities (AA) is limited by the normal organ maximum tolerated biologic effective doses (MTBEDs) arising from the combined radiopharmaceuticals. Dose limiting normal organs are expected to be the lungs for 131I-tositumomab and the liver for 90Y-ibritumomab tiuxetan in myeloablative NHL treatment regimens. By plotting the limiting normal organ constraints as a function of the AAs and calculating tumor biological effective dose (BED) along the normal organ MTBED limits, the optimal combination of activities is obtained. The model was tested using previously acquired patient normal organ and tumor kinetic data and MTBED values taken from the literature. Results The average AA values based solely on normal organ constraints was (19.0 ± 8.2) GBq with a range of 3.9 – 36.9 GBq for 131I-tositumomab, and (2.77 ± 1.64) GBq with a range of 0.42 – 7.54 GBq for 90Y-ibritumomab tiuxetan. Tumor BED optimization results were calculated and plotted as a function of AA for 5 different cases, established using patient normal organ kinetics for the two radiopharmaceuticals. Results included AA ranges

  16. Binding Procurement

    NASA Technical Reports Server (NTRS)

    Rao, Gopalakrishna M.; Vaidyanathan, Hari

    2007-01-01

    This viewgraph presentation reviews the use of the binding procurement process in purchasing Aerospace Flight Battery Systems. NASA Engineering and Safety Center (NESC) requested NASA Aerospace Flight Battery Systems Working Group to develop a set of guideline requirements document for Binding Procurement Contracts.

  17. Radiopharmaceutical stannic Sn-117m chelate compositions and methods of use

    DOEpatents

    Srivastava, Suresh C.; Meinken, George E.

    2001-01-01

    Radiopharmaceutical compositions including .sup.117m Sn labeled stannic (Sn.sup.4+) chelates are provided. The chelates are preferably polyhydroxycarboxylate, such as oxalates, tartrates, citrates, malonates, gluconates, glucoheptonates and the like. Methods of making .sup.117m Sn-labeled (Sn.sup.4+) polyhydroxycarboxylic chelates are also provided. The foregoing pharmaceutical compositions can be used in methods of preparing bone for scintigraphical analysis, for radiopharmaceutical skeletal imaging, treatment of pain resulting from metastatic bone involvement, treatment of primary bone cancer, treatment of cancer resulting from metastatic spread to bone from other primary cancers, treatment of pain resulting from rheumatoid arthritis, treatment of bone/joint disorders and to monitor radioactively the skeletal system.

  18. Development of a modular system for the synthesis of PET [(11)C]labelled radiopharmaceuticals.

    PubMed

    Boschi, Stefano; Lodi, Filippo; Cicoria, Gianfranco; Raul Ledesma, Jorge; Knopp, Roger; Rizzello, Anna; Di Pierro, Donato; Trespidi, Silvia; Marengo, Mario

    2009-10-01

    [((11))C]labelled radiopharmaceuticals as N-[(11)C]methyl-choline ([(11)C]choline), l-(S-methyl-[(11)C])methionine ([(11)C]methionine) and [(11)C]acetate have gained increasing importance in clinical PET and for the routine production of these radiopharmaceuticals, simple and reliable modules are needed to produce clinically relevant radioactivity. On the other hand, flexible devices are needed not only for the routine synthesis but also for more complex applications as the development of new tracers. The aim of this work was the adaptation of an Eckert Ziegler modular system for easy routine synthesis of [(11)C]choline, [(11)C]methionine and [(11)C]acetate using components that account for straightforward scaling up and upgrades. PMID:19535255

  19. Internal dose assessment for 211At α-emitter in isotonic solution as radiopharmaceutical

    NASA Astrophysics Data System (ADS)

    Yuminov, O. A.; Fotina, O. V.; Priselkova, A. B.; Tultaev, A. V.; Platonov, S. Yu.; Eremenko, D. O.; Drozdov, V. A.

    2003-12-01

    The functional fitness of the α-emitter 211At for radiotherapy of the thyroid gland cancer is evaluated. Radiation doses are calculated using the MIRD method and previously obtained pharmacokinetic data for 211At in isotonic solution and for 123I as sodium iodide. Analysis of the 211At radiation dose to the thyroid gland suggests that this radiopharmaceutical may be predominantly used for the treatment of the thyroid cancer.

  20. [Computer simulated images of radiopharmaceutical distributions in anthropomorphic phantoms]. Performance report

    SciTech Connect

    Not Available

    1991-05-17

    We have constructed an anatomically correct human geometry, which can be used to store radioisotope concentrations in 51 various internal organs. Each organ is associated with an index number which references to its attenuating characteristics (composition and density). The initial development of Computer Simulated Images of Radiopharmaceuticals in Anthropomorphic Phantoms (CSIRDAP) over the first 3 years has been very successful. All components of the simulation have been coded, made operational and debugged.

  1. Development new radiopharmaceutical based on 5-thio-d- glucose labeled technetium-99m

    NASA Astrophysics Data System (ADS)

    Stasyuk, E. S.; Skuridin, V. S.; Ilina, E. A.; Rogov, A. S.; Nesterov, E. A.; Sadkin, V. L.; Larionova, L. A.; Varlamova, N. V.; Zelchan, R.

    2016-06-01

    The article considers the obtaining and possibility of using 5-thio-D-glucose labeled technetium-99m for the diagnosis of malignant tumors by single photon emission computed tomography. The analysis of the level of international developments of radiopharmaceuticals based on derivatives of glucose has been carried out. Also the article provides information on of using experimental batches of lyophilisate on the basis of 5-thio-D-glucose for preliminary biomedical testing on the mice.

  2. Preparation of gallium-68 radiopharmaceuticals for positron tomography. Progress report, November 1, 1977-October 31, 1980

    SciTech Connect

    Welch, M.J.

    1980-06-01

    Although the germanium-68 ..-->.. gallium-68 generator is probably the only source of positron-emitting radionuclides that could enable the widespread application of positron tomography, the commercially available /sup 68/Ga//sup 68/Ge generator system suffers from several major disadvantages. The most important of these is that the generator is eluted with EDTA, which forms a very strong chelate with gallium. In order to produce radiopharmaceuticals other than /sup 68/Ga-EDTA, it is first necessary to break the stable EDTA complex and remove all traces of EDTA. This procedure adds several steps and a significant amount of time to procedures for preparing /sup 68/Ga-radiopharmaceuticals. We have developed a new generator using a solvent extraction system which will produce /sup 68/Ga-oxine (8-hydroxyquinoline), a weak chelate. Using this agent we have synthesized several /sup 68/Ga-radiopharmaceuticals and tested them in vitro and in vivo. We have also carried out some preliminary studies to compare generator systems which produce /sup 68/Ga in an ionic form. Attempts have been made using polarographic and chromatographic techniques, and in vivo distribution data to investigate the stability of radiogallium complexes with a series of potentially lipophilic complexing agents.

  3. Bone-seeking radiopharmaceuticals as targeted agents of osteosarcoma: samarium-153-EDTMP and radium-223.

    PubMed

    Anderson, Peter M; Subbiah, Vivek; Rohren, Eric

    2014-01-01

    Osteosarcoma is a cancer characterized by formation of bone by malignant cells. Routine bone scan imaging with Tc-99m-MDP is done at diagnosis to evaluate primary tumor uptake and check for bone metastases. At time of relapse the Tc-99m-MDP bone scan also provides a specific means to assess formation of bone by malignant osteosarcoma cells and the potential for bone-seeking radiopharmaceuticals to deliver radioactivity directly into osteoblastic osteosarcoma lesions. This chapter will review and compare a bone-seeking radiopharmaceutical that emits beta-particles, samarium-153-EDTMP, with an alpha-particle emitter, radium-223. The charged alpha particles from radium-223 have far more mass and energy than beta particles (electrons) from Sm-153-EDTMP. Because radium-223 has less marrow toxicity and more radiobiological effectiveness, especially if inside the bone forming cancer cell than samarium-153-EDTMP, radium-223 may have greater potential to become widely used against osteosarcoma as a targeted therapy. Radium-223 also has more potential to be used with chemotherapy against osteosarcoma and bone metastases. Because osteosarcoma makes bone and radium-223 acts like calcium, this radiopharmaceutical could possibly become a new targeted means to achieve safe and effective reduction of tumor burden as well as facilitate better surgery and/or radiotherapy for difficult to resect large, or metastatic tumors. PMID:24924181

  4. In vitro assays for assessing the potential for copper complexes to function as radiopharmaceutical agents.

    PubMed

    Barnard, P J; Bayly, S R; Holland, J P; Dilworth, J R; Waghorn, P A

    2008-09-01

    A series of chemical in vitro assays are described to provide a rapid initial assessment of the in vivo stability and biological behaviour of potential new copper(II) based radiopharmaceutical agents. Chemical challenges using an excess of cysteine, glutathione (GSH) and histidine, which are models of S- and N-donor molecules found in vivo, are used to provide a measure of the potential for loss of the copper(II) ion from the radiopharmaceutical as a result of ligand dissociation. In addition, thiol containing molecules such as cysteine and GSH provide a redox challenge, whereby the copper(II) complex may be reduced to give a copper(I) species. The stability of the copper(I) species toward oxidation, protonation, and ligand dissociation may be crucial in determining the biodistribution, the biological half-life and excretion mechanisms of a potential radiopharmaceutical. Further evaluation of the redox stability is assessed using the ubiquitous biological reductant ascorbic acid. The relative stability of a complex with respect to ligand dissociation in human serum provides one of the most important experiments assessing the potential of a complex to be used in vivo. Further challenge experiments with serum proteins such as thioredoxin and serum albumin can be used to provide more detailed information on the probable fate of the complex in serum. Evaluation of complex stability and speciation over a range of pH values may also be used to obtain information on potential biodistribution. PMID:18551094

  5. Harvard-MIT research program in short-lived radiopharmaceuticals. Final report

    SciTech Connect

    Adelstein, S.J.

    1995-02-01

    The Harvard-MIT Research Program in Short-lived Radiopharmaceuticals was established in 1977 to foster interaction among groups working in radiopharmaceutical chemistry at Harvard Medical School, the Massachusetts Institute of Technology, and the Massachusetts General Hospital. To this was added a group at The Childrens Hospital. From these collaborations and building upon the special strengths of the participating individuals, laboratories and institutions, it was hoped that original approaches would be found for the design of new, clinically useful, radiolabeled compounds. The original thrust of this proposal included: (a) examination of the coordination chemistry of technetium as a basis for rational radiopharmaceutical design, (b) development of an ultrashort-lived radionuclide generator for the diagnosis of congenital heart disease in newborns, (c) synthesis of receptor-site-directed halopharmaceuticals, (d) improved facile labeling of complex molecules with positron-emitting radionuclides. The authors` 1986 proposal was oriented toward organs and disease, emphasizing radiolabeled agents that delineate specific functions and the distribution of receptors in brain, heart, and tumors. In 1989, they further refined their purposes and focused on two major aims: (a) synthesis and utilization of neutral technetium and rhenium complexes of high specific activity, and (b) development of new approaches to the radiolabeling of proteins, peptides, immunoglobulins, and their fragments. In 1992, the authors amended this proposal to concentrate their efforts on biologically active peptides and proteins for targeted radiodiagnosis and therapy.

  6. Traceability from governmental producers of radiopharmaceuticals in measuring (18)F in Brazil.

    PubMed

    Oliveira, A E; Iwahara, A; Silva, C J; Cruz, P A L; Poledna, R; Silva, R L; Laranjeira, A S; Delgado, J U; Tauhata, L; Loureiro, J S; Toledo, B C; Braghirolli, A M S; Andrade, E A L; Silva, J L; Hernandes, H O K; Valente, E S; Dalle, H M; Almeida, V M; Silva, T G; Fragoso, M C F; Oliveira, M L; Nascimento, E S S; Oliveira, E M; Herrerias, R; Souza, A A; Bambalas, E; Bruzinga, W A

    2016-03-01

    Since the inception of its proficiency test program to evaluate radionuclide measurement in hospitals and clinics, the National Metrology Laboratory of Ionizing Radiation-LNMRI, that represents Brazilian National Metrology Institute (NMI) for ionizing radiation has expanded its measurement and calibration capability. Requirements from the National Health Surveillance Agency from Ministry of Health (ANVISA), to producers of radiopharmaceuticals provided an opportunity to improve the full traceability chain to the highest level. Fluorodeoxyglucose (FDG-(18)F) is the only radiopharmaceutical simultaneously produced by all Brazilian radiopharmaceutical production centers (RPCs). By running this proficiency test, LNMRI began to provide them with the required traceability. For evaluation, the ratio of RPC to reference value results and ISO/IEC17043:2010 criteria were used. The reference value established as calibration factor on the secondary standard ionization chamber was obtained from three absolute measurements systems, and routinely confirmed in each round of proficiency test by CIEMAT/NIST liquid scintillation counting. The γ-emitting impurities were checked using a High-Purity Germanium (HPGe) detector. The results show that Brazilian RPCs are in accordance with (accuracy within ±10%) the Brazilian standard for evaluation of measurements with radionuclide calibrators (CNEN NN 3.05., 2013). Nevertheless, the RPCs should improve the methodology of uncertainty estimates, essential when using the statistical criteria of ISO/IEC 17043 standard, in addition to improving accuracy to levels consistent with their position in the national traceability chain. PMID:26688362

  7. SU-E-I-82: PET Radiopharmaceuticals for Prostate Cancer Imaging: A Review

    SciTech Connect

    Fernandes, F; Silva, D da; Rodrigues, L

    2015-06-15

    Purpose: The aim of this work was to review new and clinical practice PET radiopharmaceuticals for prostate cancer imaging. Methods: PET radiopharmaceuticals were reviewed on the main databases. Availability, dosimetry, accuracy and limitations were considered. Results: The following radioisotopes with respective physical half-life and mean positron energy were found: {sup 18}F (109,7 min, 249,8 keV), {sup 89}Zr (78,4 hs, 395,5 keV), {sup 11}C (20,4 min, 385,7 keV) and {sup 68}Ga (67,8 min, 836 keV). {sup 68}Ga was the only one not produced by cyclotron. Radiopharmaceuticals uptake by glucose metabolism ({sup 18}F-FDG), lipogenesis ({sup 11}C-Choline and {sup 11}C-Acetate), amino acid transport (Anti-{sup 18}F-FACBC), bone matrix ({sup 18}F-NaF), prostatespecific membrane antigen ({sup 68}Ga-PSMA and {sup 89}Zr-J591), CXCR receptors ({sup 89}Ga-Pentixafor), adrenal receptors ({sup 18}F-FDHT) and gastrin release peptide receptor (bombesin analogue). Most of radiopharmaceuticals are urinary excretion, so bladder is the critical organ. 11C-choline (pancreas), Anti-{sup 18}FFACBC (liver) and {sup 18}F-FBDC (stomach wall) are the exception. Higher effective dose was seen {sup 18}F-NaF (27 μSv/MBq) while the lowest was {sup 11}CAcetate (3,5 μSv/MBq). Conclusion: Even though {sup 18}F-FDG has a large availability its high urinary excretion and poor uptake to slow growing disease offers weak results for prostate cancer. Better accuracy is obtained when {sup 18}F-NaF is used for bone metastatic investigation although physicians tend to choose bone scintigraphy probably due to its cost and practice. Many guidelines in oncology consider {sup 11}C or {sup 18}F labeled with Choline the gold standard for biochemical relapse after radical treatment. Local, lymph node and distant metastatic relapse can be evaluated at same time with this radiopharmaceutical. There is no consensus over bigger urinary excretion for {sup 18}F labeling. Anti-{sup 18}F-FACBC, {sup 68}Ga-PSMA and {sup

  8. New radiopharmaceutical agents for the treatment of castration-resistant prostate cancer.

    PubMed

    Maffioli, L; Florimonte, L; Costa, D C; Correia Castanheira, J; Grana, C; Luster, M; Bodei, L; Chinol, M

    2015-12-01

    Prostate cancer (PCa) is the fourth most common cancer worldwide in terms of incidence and third among male, but is becoming the most common cancer in developed countries. In many patients the disease will progress despite of castration levels of testosterone, to become castration-resistant PCa (CRPC). Nearly all patients with CRPC show bone metastases. The treatment of patients with bony metastases has dramatically changed during the past three years because of new therapeutic approaches addressed to obtain pain control, reduced skeletal morbidity, and most importantly, increased survival rate. A possible therapy can be based also on the use of radiopharmaceuticals systemically administered to slow or reverse the bone metastatic progression. In facts bone-homing radiopharmaceuticals are taken up in areas of high bone turnover, including areas with high osteoblastic activity. Recently, a bone targeting radiopharmaceutical, Radium-223 dichloride was added to this group of drugs clearly representing a new generation of radiopharmaceutical in bone therapy. Clinical trials had shown that the treatment with Ra-223 allowed the reduction of the risk of death respect to placebo. No other radiometabolic treatment achieved such result, evidentiating the disease-modifying properties of this bone-homing radiopharmaceutical. In an effort to treat patients with disseminated PCa, who became resistant to hormonal therapy, molecular targets have been recently identified. Prostate specific membrane antigen (PSMA) is one attractive target for diagnosis and therapy of metastasized PCa since its expression levels are directly correlated to androgen independence, metastasis, and progression. Gastrin-releasing peptide receptors (GRPr) are also highly overexpressed in PCa. Numerous studies suggest the possibility of a high PCa-specific signal with radiolabeled bombesin analogs targeting GRPr. Low molecular weight peptides directed against these molecular targets have been radiolabeled

  9. Evaluation of [(11)C]N-Methyl Lansoprazole as a Radiopharmaceutical for PET Imaging of Tau Neurofibrillary Tangles.

    PubMed

    Shao, Xia; Carpenter, Garrett M; Desmond, Timothy J; Sherman, Phillip; Quesada, Carole A; Fawaz, Maria; Brooks, Allen F; Kilbourn, Michael R; Albin, Roger L; Frey, Kirk A; Scott, Peter J H

    2012-11-01

    [(11)C]N-Methyl lansoprazole ([(11)C]NML, 3) was synthesized and evaluated as a radiopharmaceutical for quantifying tau neurofibrillary tangle (NFT) burden using positron emission tomography (PET) imaging. [(11)C]NML was synthesized from commercially available lansoprazole in 4.6% radiochemical yield (noncorrected RCY, based upon [(11)C]MeI), 99% radiochemical purity, and 16095 Ci/mmol specific activity (n = 5). Log P was determined to be 2.18. A lack of brain uptake in rodent microPET imaging revealed [(11)C]NML to be a substrate for the rodent permeability-glycoprotein 1 (PGP) transporter, but this could be overcome by pretreating with cyclosporin A to block the PGP. Contrastingly, [(11)C]NML was not found to be a substrate for the primate PGP, and microPET imaging in rhesus revealed [(11)C]NML uptake in the healthy primate brain of ∼1600 nCi/cc maximum at 3 min followed by rapid egress to 500 nCi/cc. Comparative autoradiography between wild-type rats and transgenic rats expressing human tau (hTau +/+) revealed 12% higher uptake of [(11)C]NML in the cortex of brains expressing human tau. Further autoradiography with tau positive brain samples from progressive supranuclear palsy (PSP) patients revealed colocalization of [(11)C]NML with tau NFTs identified using modified Bielschowsky staining. Finally, saturation binding experiments with heparin-induced tau confirmed K d and Bmax values of [(11)C]NML as 700 pM and 0.214 fmol/μg, respectively. PMID:24900410

  10. Harvard--MIT research program in short-lived radiopharmaceuticals

    SciTech Connect

    Not Available

    1991-03-01

    This report describes progress on five projects. The first project showed a 1000 fold concentration of the cationic complex {sup 99m}Tc (MIBI) in heart cell mitochondria vs heart cell cytoplasm, as determined by high resolution electron probe microanalysis. Additional technetium-99m based complexes are being developed and tested. The second project involves evaluating technetium acetylacteonates as potential indicators of cerebral blood flow. An intermediate in the synthesis of a technetium porphyrin complex has been synthesized; an oxotechnetium(V)-2,4-pentanedione complex has been prepared and is currently being characterized. The third project involves using radio labelled antibodies for diagnosis and treatment of cancer. An early discovery was that chloramine-T based iodination protocols resulted in a reversal of the charge on mouse lgGs. Immunoperoxidase-labelled monoclonal antibody MOv 18 was shown to bind specifically to the most frequent ovarian aderon carcinomas, and not to healthy tissue, making this antibody a good candidate for immunotherapy or immunodetection. Work on a specific immunotherapy protocol suffered a setback when one reagent, a {sup 125}I-biotin complex, proved to be unstable in vivo. The fourth project involves labelling antibodies with positron emitting radionuclides. Radiofluorination was accomplished through reductive alkylation of {sup 18}F-aldehyde, or pentafluorophenyl esters. Radioiodination was accomplished using alkyl-tin derivation exchange. The fifth project examined antibody modification for use in radioimmune imaging. Technetium-99m-labelled lgG was shown to be biologically equivalent to Indium-III-labelled lgG for imaging focal sites of inflamation. Also, Indium III labelling of small bioactive peptides was examined as a means of imaging important physiological processes. 44 refs., 2 figs.

  11. Proliferation dangers associated with nuclear medicine: getting weapons-grade uranium out of radiopharmaceutical production.

    PubMed

    Williams, Bill; Ruff, Tilman A

    2007-01-01

    Abolishing the threat of nuclear war requires the outlawing of nuclear weapons and dismantling current nuclear weapon stockpiles, but also depends on eliminating access to fissile material (nuclear weapon fuel). The near-universal use of weapons-grade, highly enriched uranium (HEU) to produce radiopharmaceuticals is a significant proliferation hazard. Health professionals have a strategic opportunity and obligation to progress the elimination of medically-related commerce in HEU, closing one of the most vulnerable pathways to the much-feared 'terrorist bomb'. PMID:17987979

  12. USCEA/NIST measurement assurance programs for the radiopharmaceutical and nuclear power industries

    SciTech Connect

    Golas, D.B.

    1993-12-31

    In cooperation with the U.S. Council for Energy Awareness (USCEA), the National Institute of Standards and Technology (NIST) supervises and administers two measurement assurance programs for radioactivity measurement traceability. One, in existence since the mid 1970s, provides traceability to suppliers of radiochemicals and radiopharmaceuticals, dose calibrators, and nuclear pharmacy services. The second program, begun in 1987, provides traceability to the nuclear power industry for utilities, source suppliers, and service laboratories. Each program is described, and the results of measurements of samples of known, but undisclosed activity, prepared at NIST and measured by the participants are presented.

  13. Calculating patient-specific doses in X-ray diagnostics and from radiopharmaceuticals

    NASA Astrophysics Data System (ADS)

    Lampinen, Juha Sakari

    2000-06-01

    The risk associated with exposure to ionising radiation is dependent on the characteristics of the exposed individual. The size and structure of the individual influences the absorbed dose distribution in the organs. Traditional methods used to calculate the patient organ doses are based on standardised calculation phantoms, which neglect the variance of the patient size or even sex. Methods for patient specific dosimetry in the fields of X-ray diagnostics and diagnostic and therapeutic use of radiopharmaceuticals were proposed in this thesis. A computer program, ODS-60, for calculating organ doses from diagnostic X-ray exposures was presented. The calculation is done in a patient specific phantom with depth dose and profile algorithms fitted to Monte Carlo simulation data from a previous study. Improvements to the version reported earlier were introduced, e.g. bone attenuation was implemented. The applicability of the program to determine patient doses from complex X-ray examinations (barium enema examination) was studied. The conversion equations derived for female and male patients as a function of patient weight gave the smallest deviation from the actual patient doses when compared to previous studies. Another computer program, Intdose, was presented for calculation of the dose distribution from radiopharmaceuticals. The calculation is based on convolution of an isotope specific point dose kernel with activity distribution, obtained from single photon emission computed tomography (SPECT) images. Anatomical information is taken from magnetic resonance (MR) or computed tomography (CT) images. According to a phantom study, Intdose agreed within 3% with measurements. For volunteers administered diagnostic radiopharmaceuticals, the results given by Intdose were found to agree with traditional methods in cases of medium sized patients. For patients undergoing systemic radiation therapy, the results by Intdose differed from measurements due to dynamic biodistribution

  14. Radiopharmaceuticals for radiation synovectomy: Evaluation of two yttrium-90 particulate agents

    SciTech Connect

    Davis, M.A.; Chinol, M.

    1989-06-01

    Radiation synovectomy, a noninvasive therapeutic alternative to surgical synovectomy, has not gained widespread acceptance in the United States because of the lack of a suitable radiopharmaceutical. Two new radioactive particles, (/sup 90/Y)Ca oxalate and (/sup 90/Y)ferric hydroxide macroaggregates (FHMA), were developed in our laboratory and evaluated for size, stability, and joint leakage. More than 90% of the (/sup 90/Y)Ca oxalate particles were in the optimal size range of 1-10 microns, and the unbound activity in serum and synovial fluid was 3.7% to 5.0%. Following injection in rabbit knees, leakage of (/sup 90/Y)Ca oxalate was 5 +/- 2%, with localization primarily in the bone and virtually no uptake by the lymph nodes or liver. Yttrium-90 FHMA particles were larger (95% greater than 10 microns), and at least on a microscopic level, appeared to distribute homogeneously over the articular surface. Leakage of (/sup 90/Y)FHMA was initially less but eventually slightly exceeded that of (/sup 90/Y)Ca oxalate. Nevertheless, both radiopharmaceuticals can provide a satisfactory therapeutic dose to the knee with less than half the leakage and a marked reduction in absorbed dose to nontarget tissues compared to previously tested agents. Ease of preparation, physical characteristics of the /sup 90/Y beta ray, and apparent lack of substantial leakage from the joint make these agents extremely attractive for clinical evaluation in rheumatoid arthritis patients who are unresponsive to medical therapy.

  15. Monte Carlo Assessments of Absorbed Doses to the Hands of Radiopharmaceutical Workers Due to Photon Emitters

    SciTech Connect

    Ilas, Dan; Eckerman, Keith F; Karagiannis, Harriet

    2009-01-01

    This paper describes the characterization of radiation doses to the hands of nuclear medicine technicians resulting from the handling of radiopharmaceuticals. Radiation monitoring using ring dosimeters indicates that finger dosimeters that are used to show compliance with applicable regulations may overestimate or underestimate radiation doses to the skin depending on the nature of the particular procedure and the radionuclide being handled. To better understand the parameters governing the absorbed dose distributions, a detailed model of the hands was created and used in Monte Carlo simulations of selected nuclear medicine procedures. Simulations of realistic configurations typical for workers handling radiopharmaceuticals were performedfor a range of energies of the source photons. The lack of charged-particle equilibrium necessitated full photon-electron coupled transport calculations. The results show that the dose to different regions of the fingers can differ substantially from dosimeter readings when dosimeters are located at the base of the finger. We tried to identify consistent patterns that relate the actual dose to the dosimeter readings. These patterns depend on the specific work conditions and can be used to better assess the absorbed dose to different regions of the exposed skin.

  16. Radiation for bone metastases: conventional techniques and the role of systemic radiopharmaceuticals.

    PubMed

    Janjan, N A

    1997-10-15

    Pain management often is difficult in patients with bone metastases. Metastatic disease represents >40% of oncologic practice, and >70% of patients with metastatic disease have uncontrolled cancer-related pain. Significant morbidity caused by pathologic fracture and spinal cord compression can result from untreated bone metastases. Representing both a manifestation of systemic disease as well as causing localized symptoms, bone metastases require a multidisciplinary therapeutic approach. Radiation therapy provides both localized and systemic treatment options in addition to chemohormonal therapies and surgery. External beam irradiation provides palliation in >70% of patients through tumor regression of a localized lesion. Systemic radiopharmaceuticals treat multifocal disease either alone or as an adjuvant to external beam irradiation. Efficient and comprehensive management of bone metastases is imperative because of the associated symptoms, prior therapies, complex underlying medical problems, and clinical presentations that often require emergent interventions. Intensification of pain may be observed with hormonal therapy and systemic radiopharmaceuticals. Symptomatic relief from antineoplastic therapies generally requires 4-12 weeks and may be related to reossification. Symptoms, occurring due to the disease and/or while awaiting response to therapy, must be aggressively managed. Persistent or recurrent pain after therapy may be due to bony instability or fracture before reossification occurs. An Interdisciplinary Bone Metastases Clinic, with representatives from Diagnostic Radiology, Medical Oncology, Nuclear Medicine, Orthopedic Surgery, Pain and Symptom Management, Physical Medicine and Rehabilitation, and Radiation Oncology, was developed that allows coordinated evaluation, treatment, and symptom management of these complex clinical presentations. PMID:9362430

  17. 18F-Labeled Silicon-Based Fluoride Acceptors: Potential Opportunities for Novel Positron Emitting Radiopharmaceuticals

    PubMed Central

    Bernard-Gauthier, Vadim; Wängler, Carmen; Wängler, Bjoern; Schirrmacher, Ralf

    2014-01-01

    Background. Over the recent years, radiopharmaceutical chemistry has experienced a wide variety of innovative pushes towards finding both novel and unconventional radiochemical methods to introduce fluorine-18 into radiotracers for positron emission tomography (PET). These “nonclassical” labeling methodologies based on silicon-, boron-, and aluminium-18F chemistry deviate from commonplace bonding of an [18F]fluorine atom (18F) to either an aliphatic or aromatic carbon atom. One method in particular, the silicon-fluoride-acceptor isotopic exchange (SiFA-IE) approach, invalidates a dogma in radiochemistry that has been widely accepted for many years: the inability to obtain radiopharmaceuticals of high specific activity (SA) via simple IE. Methodology. The most advantageous feature of IE labeling in general is that labeling precursor and labeled radiotracer are chemically identical, eliminating the need to separate the radiotracer from its precursor. SiFA-IE chemistry proceeds in dipolar aprotic solvents at room temperature and below, entirely avoiding the formation of radioactive side products during the IE. Scope of Review. A great plethora of different SiFA species have been reported in the literature ranging from small prosthetic groups and other compounds of low molecular weight to labeled peptides and most recently affibody molecules. Conclusions. The literature over the last years (from 2006 to 2014) shows unambiguously that SiFA-IE and other silicon-based fluoride acceptor strategies relying on 18F− leaving group substitutions have the potential to become a valuable addition to radiochemistry. PMID:25157357

  18. Improved dose-volume histogram estimates for radiopharmaceutical therapy by optimizing quantitative SPECT reconstruction parameters

    NASA Astrophysics Data System (ADS)

    Cheng, Lishui; Hobbs, Robert F.; Segars, Paul W.; Sgouros, George; Frey, Eric C.

    2013-06-01

    In radiopharmaceutical therapy, an understanding of the dose distribution in normal and target tissues is important for optimizing treatment. Three-dimensional (3D) dosimetry takes into account patient anatomy and the nonuniform uptake of radiopharmaceuticals in tissues. Dose-volume histograms (DVHs) provide a useful summary representation of the 3D dose distribution and have been widely used for external beam treatment planning. Reliable 3D dosimetry requires an accurate 3D radioactivity distribution as the input. However, activity distribution estimates from SPECT are corrupted by noise and partial volume effects (PVEs). In this work, we systematically investigated OS-EM based quantitative SPECT (QSPECT) image reconstruction in terms of its effect on DVHs estimates. A modified 3D NURBS-based Cardiac-Torso (NCAT) phantom that incorporated a non-uniform kidney model and clinically realistic organ activities and biokinetics was used. Projections were generated using a Monte Carlo (MC) simulation; noise effects were studied using 50 noise realizations with clinical count levels. Activity images were reconstructed using QSPECT with compensation for attenuation, scatter and collimator-detector response (CDR). Dose rate distributions were estimated by convolution of the activity image with a voxel S kernel. Cumulative DVHs were calculated from the phantom and QSPECT images and compared both qualitatively and quantitatively. We found that noise, PVEs, and ringing artifacts due to CDR compensation all degraded histogram estimates. Low-pass filtering and early termination of the iterative process were needed to reduce the effects of noise and ringing artifacts on DVHs, but resulted in increased degradations due to PVEs. Large objects with few features, such as the liver, had more accurate histogram estimates and required fewer iterations and more smoothing for optimal results. Smaller objects with fine details, such as the kidneys, required more iterations and less

  19. Improved dose-volume histogram estimates for radiopharmaceutical therapy by optimizing quantitative SPECT reconstruction parameters.

    PubMed

    Cheng, Lishui; Hobbs, Robert F; Segars, Paul W; Sgouros, George; Frey, Eric C

    2013-06-01

    In radiopharmaceutical therapy, an understanding of the dose distribution in normal and target tissues is important for optimizing treatment. Three-dimensional (3D) dosimetry takes into account patient anatomy and the nonuniform uptake of radiopharmaceuticals in tissues. Dose-volume histograms (DVHs) provide a useful summary representation of the 3D dose distribution and have been widely used for external beam treatment planning. Reliable 3D dosimetry requires an accurate 3D radioactivity distribution as the input. However, activity distribution estimates from SPECT are corrupted by noise and partial volume effects (PVEs). In this work, we systematically investigated OS-EM based quantitative SPECT (QSPECT) image reconstruction in terms of its effect on DVHs estimates. A modified 3D NURBS-based Cardiac-Torso (NCAT) phantom that incorporated a non-uniform kidney model and clinically realistic organ activities and biokinetics was used. Projections were generated using a Monte Carlo (MC) simulation; noise effects were studied using 50 noise realizations with clinical count levels. Activity images were reconstructed using QSPECT with compensation for attenuation, scatter and collimator-detector response (CDR). Dose rate distributions were estimated by convolution of the activity image with a voxel S kernel. Cumulative DVHs were calculated from the phantom and QSPECT images and compared both qualitatively and quantitatively. We found that noise, PVEs, and ringing artifacts due to CDR compensation all degraded histogram estimates. Low-pass filtering and early termination of the iterative process were needed to reduce the effects of noise and ringing artifacts on DVHs, but resulted in increased degradations due to PVEs. Large objects with few features, such as the liver, had more accurate histogram estimates and required fewer iterations and more smoothing for optimal results. Smaller objects with fine details, such as the kidneys, required more iterations and less

  20. Current activities in the ICRP concerning estimation of radiation doses to patients from radiopharmaceuticals for diagnostic use

    NASA Astrophysics Data System (ADS)

    Mattsson, S.; Johansson, L.; Leide-Svegborn, S.; Liniecki, J.; Nosske, D.; Riklund, K.; Stabin, M.; Taylor, D.

    2011-09-01

    A Task Group within the ICRP Committees 2 and 3 is continuously working to improve absorbed dose estimates to patients investigated with radiopharmaceuticals. The work deals with reviews of the literature, initiation of new or complementary studies of the biokinetics of a compound and dose estimates. Absorbed dose calculations for organs and tissues have up to now been carried out using the MIRD formalism. There is still a lack of necessary biokinetic data from measurements in humans. More time series obtained by nuclear medicine imaging techniques such as whole-body planar gamma-camera imaging, SPECT or PET are highly desirable for this purpose. In 2008, a new addendum to ICRP Publication 53 was published under the name of ICRP Publication 106 containing biokinetic data and absorbed dose information to organs and tissues of patients of various ages for radiopharmaceuticals in common use. That report also covers a number of generic models and realistic maximum models covering other large groups of substances (e.g. "123I-brain receptor substances"). Together with ICRP Publication 80, most radiopharmaceuticals in clinical use at the time of publication were covered except the radioiodine labeled compounds for which the ICRP dose estimates are still found in Publication 53. There is an increasing use of new radiopharmaceuticals, especially PET-tracers and the TG has recently finished its work with biokinetic and dosimetric data for 18F-FET, 18F-FLT and 18F-choline. The work continues now with new data for 11C-raclopride, 11C-PiB and 123I-ioflupan as well as re-evaluation of published data for 82Rb-chloride, 18F-fluoride and radioiodide. This paper summarises published ICRP-information on dose to patients from radiopharmaceuticals and gives some preliminary data for substances under review.

  1. Overview and perspectives on automation strategies in (68)Ga radiopharmaceutical preparations.

    PubMed

    Boschi, Stefano; Malizia, Claudio; Lodi, Filippo

    2013-01-01

    The renaissance of (68)Ga radiopharmacy has led to great advances in automation technology. The availability of a highly efficient, reliable, long-lived (68)Ge/(68)Ga generator system along with a well-established coordination chemistry based on bifunctional chelating agents have been the bases of this development in (68)Ga radiopharmacy. Syntheses of (68)Ga peptides were originally performed by manual or semiautomated systems, but increasing clinical demand, radioprotection, and regulatory issues have driven extensive automation of their production process. Several automated systems, based on different post-processing of the (68)Ga generator eluate, on different engineering, and on fixed tubing or disposable cassette approaches, have been developed and are discussed in this chapter. Since automatic systems for preparation of radiopharmaceuticals should comply with qualification and validation protocols established by regulations such as current Good Manufacturing Practices (cGMP) and local regulations, some regulatory issues and the more relevant qualification protocols are also discussed. PMID:22918752

  2. Cage-like bifunctional chelators, copper-64 radiopharmaceuticals and PET imaging using the same

    DOEpatents

    Conti, Peter S.; Cai, Hancheng; Li, Zibo; Liu, Shuanglong

    2016-08-02

    Disclosed is a class of versatile Sarcophagine based bifunctional chelators (BFCs) containing a hexa-aza cage for labeling with metals having either imaging, therapeutic or contrast applications radiolabeling and one or more linkers (A) and (B). The compounds have the general formula ##STR00001## where A is a functional group selected from group consisting of an amine, a carboxylic acid, an ester, a carbonyl, a thiol, an azide and an alkene, and B is a functional group selected from the group consisting of hydrogen, an amine, a carboxylic acid, and ester, a carbonyl, a thiol, an azide and an alkene. Also disclosed are conjugate of the BFC and a targeting moiety, which may be a peptide or antibody. Also disclosed are metal complexes of the BFC/targeting moiety conjugates that are useful as radiopharmaceuticals, imaging agents or contrast agents.

  3. Radiopharmaceuticals for assessing ABC transporters at the blood-brain barrier.

    PubMed

    Raaphorst, R M; Windhorst, A D; Elsinga, P H; Colabufo, N A; Lammertsma, A A; Luurtsema, G

    2015-04-01

    ABC transporters protect the brain by transporting neurotoxic compounds from the brain back into the blood. P-glycoprotein (P-gp) is the most investigated ABC (efflux) transporter, as it is implicated in neurodegenerative diseases such as Alzheimer's disease. Altered function of P-gp can be studied in vivo, using Positron Emission Tomography (PET). To date, several radiopharmaceuticals have been developed to image P-gp function in vivo. So far, attempts to image expression levels of P-gp using radiolabeled P-gp inhibitors have not been successful. Improved knowledge of compound behavior toward P-gp from in vitro studies should increase predictability of in vivo outcome. PMID:25669763

  4. In vivo nanoparticle-mediated radiopharmaceutical-excited fluorescence molecular imaging

    PubMed Central

    Hu, Zhenhua; Qu, Yawei; Wang, Kun; Zhang, Xiaojun; Zha, Jiali; Song, Tianming; Bao, Chengpeng; Liu, Haixiao; Wang, Zhongliang; Wang, Jing; Liu, Zhongyu; Liu, Haifeng; Tian, Jie

    2015-01-01

    Cerenkov luminescence imaging utilizes visible photons emitted from radiopharmaceuticals to achieve in vivo optical molecular-derived signals. Since Cerenkov radiation is weak, non-optimum for tissue penetration and continuous regardless of biological interactions, it is challenging to detect this signal with a diagnostic dose. Therefore, it is challenging to achieve useful activated optical imaging for the acquisition of direct molecular information. Here we introduce a novel imaging strategy, which converts γ and Cerenkov radiation from radioisotopes into fluorescence through europium oxide nanoparticles. After a series of imaging studies, we demonstrate that this approach provides strong optical signals with high signal-to-background ratios, an ideal tissue penetration spectrum and activatable imaging ability. In comparison with present imaging techniques, it detects tumour lesions with low radioactive tracer uptake or small tumour lesions more effectively. We believe it will facilitate the development of nuclear and optical molecular imaging for new, highly sensitive imaging applications. PMID:26123615

  5. In vivo nanoparticle-mediated radiopharmaceutical-excited fluorescence molecular imaging.

    PubMed

    Hu, Zhenhua; Qu, Yawei; Wang, Kun; Zhang, Xiaojun; Zha, Jiali; Song, Tianming; Bao, Chengpeng; Liu, Haixiao; Wang, Zhongliang; Wang, Jing; Liu, Zhongyu; Liu, Haifeng; Tian, Jie

    2015-01-01

    Cerenkov luminescence imaging utilizes visible photons emitted from radiopharmaceuticals to achieve in vivo optical molecular-derived signals. Since Cerenkov radiation is weak, non-optimum for tissue penetration and continuous regardless of biological interactions, it is challenging to detect this signal with a diagnostic dose. Therefore, it is challenging to achieve useful activated optical imaging for the acquisition of direct molecular information. Here we introduce a novel imaging strategy, which converts γ and Cerenkov radiation from radioisotopes into fluorescence through europium oxide nanoparticles. After a series of imaging studies, we demonstrate that this approach provides strong optical signals with high signal-to-background ratios, an ideal tissue penetration spectrum and activatable imaging ability. In comparison with present imaging techniques, it detects tumour lesions with low radioactive tracer uptake or small tumour lesions more effectively. We believe it will facilitate the development of nuclear and optical molecular imaging for new, highly sensitive imaging applications. PMID:26123615

  6. Copper complexes of bis(thiosemicarbazones): from chemotherapeutics to diagnostic and therapeutic radiopharmaceuticals.

    PubMed

    Paterson, Brett M; Donnelly, Paul S

    2011-05-01

    The molecules known as bis(thiosemicarbazones) derived from 1,2-diones can act as tetradentate ligands for Cu(II), forming stable, neutral complexes. As a family, these complexes possess fascinating biological activity. This critical review presents an historical perspective of their progression from potential chemotherapeutics through to more recent applications in nuclear medicine. Methods of synthesis are presented followed by studies focusing on their potential application as anti-cancer agents and more recent investigations into their potential as therapeutics for Alzheimer's disease. The Cu(II) complexes are of sufficient stability to be used to coordinate copper radioisotopes for application in diagnostic and therapeutic radiopharmaceuticals. Detailed understanding of the coordination chemistry has allowed careful manipulation of the metal based properties to engineer specific biological activities. Perhaps the most promising complex radiolabelled with copper radioisotopes to date is Cu(II)(atsm), which has progressed to clinical trials in humans (162 references). PMID:21409228

  7. Quantitative autoradiography with radiopharmaceuticals, Part 1: Digital film-analysis system by videodensitometry: concise communication

    SciTech Connect

    Yonekura, Y.; Brill, A.B.; Som, P.; Bennett, G.W.; Fand, I.

    1983-03-01

    A simple low-cost digital film-analysis system using videodensitometry was developed to quantitate autoradiograms. It is based on a TV-film analysis system coupled to a minicomputer. Digital sampling of transmitted light intensities through the autoradiogram is performed with 8-bit gray levels according to the selected array size (128 X 128 to 1024 X 1024). The performance characteristics of the system provide sufficient stability, uniformity, linearity, and intensity response for use in quantitative analysis. Digital images of the autoradiograms are converted to radioactivity content, pixel by pixel, using step-wedge standards. This type of low-cost system can be installed on conventional mini-computers commonly used in modern nuclear medical facilities. Quantitative digital autoradiography can play an important role, with applications stretching from dosimetry calculations of radiopharmaceuticals to metabolic studies in conjunction with positron-emission tomography.

  8. Design Features Of Microfluidic Reactor For [18F]FDG Radiopharmaceutical Synthesis

    NASA Astrophysics Data System (ADS)

    Oh, J. H.; Lee, B. N.; Nam, K. R.; Attla, G. A.; Lee, K. C.; Cjai, J. S.

    2011-06-01

    Microfluidic reactor exhibits advantages for radiopharmaceutical synthesis. Microfluidic chips can reduce the time for radiosynthesis using tiny quantities of chemical compounds. It also has a good heat transfer, performance and provides an integrated system including synthesis, separation, and purification. These advantages make FDG production. So we have designed a microreactor chip which included the whole chemical processing; water evaporation, solvent exchange, radiofluorination and so on. It was designed by using a commercial 3D CAD modeling program CATIA V5, heat transfer performance was analyzed by ANSYS, and CFX was used for analyzing fluid performance. This paper described the design of FDG synthesis system on a microchip, the relevant locations of its parts, both heat and fluid performance efficiency analysis.

  9. Effect of altered thyroid status on the transport of hepatobiliary radiopharmaceuticals

    SciTech Connect

    Pahuja, D.N.; Noronha, O.P.

    1985-10-01

    The effect of induced hypothyroidism (by feeding an antithyroid drug-propylthiouracil) on the transport and clearance of the routinely used hepatobiliary radiopharmaceuticals--radioiodinated iodine- T (131I) rose bengal and technetium-99m-N-(4-n-butylphenylcarbamoylmethyl) iminodiacetate, was studied in the rats. Hypothyroidism was associated with depressed growth and retarded clearance of these radiotracers from the in vivo system. Treatment of the hypothyroid rats with thyroxine (2-5 micrograms/100 g b.w. day) for 6 wk, restored these parameters towards normal values. These data suggest that delayed clearance of these hepatobiliary tracers could be related to reduced metabolic rate accompanied with the hypotonia and hypomotility of intestine normally observed in the hypothyroid state.

  10. Highway accident involving radiopharmaceuticals near Brookhaven, Mississippi on December 3, 1983

    SciTech Connect

    Mohr, P.B.; Mount, M.E.; Schwartz, M.W.

    1985-04-01

    A rear-end collision occurred between a passenger automobile and a luggage trailer carrying 84 packages, 76 of which contained radiopharmaceuticals, on US Highway 84 near Brookhaven, Mississippi on the afternoon of December 3, 1983. The purpose of this report is to document the mechanical circumstances of the accident, confirm the nature and quantity of radioactive materials involved, and assess the nature of the physical environment to which the packages were exposed and the response of the packages. The report consists of three major sections. The first deals wth the nature and circumstances of the accident and findings of fact. The second gives an accounting and description of the materials involved and the consequences of their exposure. The third gives an assessment and analysis of the mechanisms of damage and the conclusions which may be drawn from the investigation. 4 refs., 24 figs., 4 tabs.

  11. Positron emission tomography radiopharmaceutical studies in humans: a guide to regulations for academic researchers.

    PubMed

    Fleming, Ian N; Whelan, Mark; Baxendale, Roy; Gilbert, Fiona J; Matthews, Paul P; Aigbirhio, Franklin I

    2012-09-01

    All clinical trials are covered by a series of regulations that seek to protect the rights, safety and welfare of participating patients. The regulations covering PET studies are especially complex to interpret because of the specialized nature of the language of the regulations and of PET studies themselves. It is often unclear whether the application demands that the radiotracer used be treated as an investigational medical product. This paper is intended to act as a general guide for UK researchers planning to perform PET research in humans by clarifying key aspects of the regulations that may affect the study and/or the radiopharmaceutical manufacturing process, providing links to useful information sources, introducing the concept of a UK Medicines and Healthcare products Regulatory Agency (MHRA) PET expert panel and outlining the value of sharing investigational medical product dossiers. PMID:22773151

  12. Scaling animal to human biodistribution of the radiopharmaceutical [68Ga]Ga-PSMA-HBED-CC

    NASA Astrophysics Data System (ADS)

    Parra, Pamela Ochoa; Veloza, Stella

    2016-07-01

    The radiotracer called 68Ga-labelled Glu-urea-Lys(Ahx)-HBED-CC ([68Ga]Ga-PSMA-HBED-CC) is a novel radiophar-maceutical for the detection of prostate cancer lesions by positron emission tomography (PET) imaging. Setting up a cost-effective manual synthesis of this radiotracer and making its clinical translation in Colombia will require two important elements: the evaluation of the procedure to yield a consistent product, meeting standards of radio-chemical purity and low toxicity and then, the evaluation of the radiation dosimetry. In this paper a protocol to extrapolate the biokinetic model made in normal mice to humans by using the computer software for internal dose assessment OLINDA/EXM® is presented as an accurate and standardized method for the calculation of radiation dosimetry estimates.

  13. Theranostic Radiopharmaceuticals Based on Gold Nanoparticles Labeled with (177)Lu and Conjugated to Peptides.

    PubMed

    Ferro-Flores, Guillermina; Ocampo-García, Blanca E; Santos-Cuevas, Clara L; de María Ramírez, Flor; Azorín-Vega, Erika P; Meléndez-Alafort, Laura

    2015-01-01

    Gold nanoparticles (AuNPs) have been proposed for a variety of medical applications such as localized heat sources for cancer treatment and drug delivery systems. The conjugation of peptides to AuNPs produces stable multimeric systems with target-specific molecular recognition. Lutetium- 177 ((177)Lu) has been successfully used in peptide radionuclide therapy. Recently, (177)Lu-AuNPs conjugated to different peptides have been proposed as a new class of theranostic radiopharmaceuticals. These radioconjugates may function simultaneously as molecular imaging agents, radiotherapy systems and thermal-ablation systems. This article covers advancements in the design, synthesis, physicochemical characterization, molecular recognition assessment and preclinical therapeutic efficacy of gold nanoparticles radiolabeled with (177)Lu and conjugated to RGD (-Arg-Gly-Asp-), Lys(3)-Bombesin and Tat(49-57) peptides. PMID:25771363

  14. (177) Lu-5-Fluorouracil a potential theranostic radiopharmaceutical: radiosynthesis, quality control, biodistribution, and scintigraphy.

    PubMed

    Rasheed, Rashid; Tariq, Saleha; Naqvi, Syed Ali Raza; Gillani, Syed Jawad Hussain; Rizvi, Faheem Askari; Sajid, Muhammad; Rasheed, Shahid

    2016-08-01

    The aim of this study is to develop (177) Lu-5-Flourouracil as a potential cancer therapeutic radiopharmaceutical. 5-Flourouracil (5-FU) is widely accepted as an anticancer drug of broad spectrum fame. The labeling of 5-FU was carried out at different set of experimental conditions using high specific activity of (177) LuCl3 . The optimum conditions for maximum radiochemical yield was set: 5-FU (5 mg), (177) LuCl3 (185 MBq), diethylenetriaminepentaacetic acid (10 µg), reaction volume (2 mL), pH (5.5), temperature (80°C), and reaction time (20 min). The radiochemical labeling was assessed with Whatman No. 2 paper, instant thin layer chromatographic, and radio-HPLC, which revealed >94% labeling results with sufficient stability up to 6 h. Serum stability study also showed (177) Lu-5-FU promising stability. Biodistribution study in normal rats and rabbits showed liver, stomach, kidney, and heart as area of increased tracer accumulation just after injection, which decreased to 1.4%, 0.4%, 0.2%, and 0.39% ID/g, respectively, after 72 h. Glomerular filtration rate and cytotoxicity study results of (177) Lu-5-FU showed it had no adverse effect on renal function and nontoxic to blood cells. The promising characteristics of (177) Lu-5-FU, that is, clever elimination from kidney and nontoxic nature toward blood cells make it the radiopharmaceutical for further testing in patients for therapeutic purposes. PMID:27444959

  15. Implementation and validation of collapsed cone superposition for radiopharmaceutical dosimetry of photon emitters.

    PubMed

    Sanchez-Garcia, Manuel; Gardin, Isabelle; Lebtahi, Rachida; Dieudonné, Arnaud

    2015-10-21

    Two collapsed cone (CC) superposition algorithms have been implemented for radiopharmaceutical dosimetry of photon emitters. The straight CC (SCC) superposition method uses a water energy deposition kernel (EDKw) for each electron, positron and photon components, while the primary and scatter CC (PSCC) superposition method uses different EDKw for primary and once-scattered photons. PSCC was implemented only for photons originating from the nucleus, precluding its application to positron emitters. EDKw are linearly scaled by radiological distance, taking into account tissue density heterogeneities. The implementation was tested on 100, 300 and 600 keV mono-energetic photons and (18)F, (99m)Tc, (131)I and (177)Lu. The kernels were generated using the Monte Carlo codes MCNP and EGSnrc. The validation was performed on 6 phantoms representing interfaces between soft-tissues, lung and bone. The figures of merit were γ (3%, 3 mm) and γ (5%, 5 mm) criterions corresponding to the computation comparison on 80 absorbed doses (AD) points per phantom between Monte Carlo simulations and CC algorithms. PSCC gave better results than SCC for the lowest photon energy (100 keV). For the 3 isotopes computed with PSCC, the percentage of AD points satisfying the γ (5%, 5 mm) criterion was always over 99%. A still good but worse result was found with SCC, since at least 97% of AD-values verified the γ (5%, 5 mm) criterion, except a value of 57% for the (99m)Tc with the lung/bone interface. The CC superposition method for radiopharmaceutical dosimetry is a good alternative to Monte Carlo simulations while reducing computation complexity. PMID:26406778

  16. [A new radiopharmaceutical for bone imaging: experimental study of 99mTc-HEDTMP].

    PubMed

    Hu, Shu; Deng, Houfu; Jiang, Shubin; Luo, Shunzhong; Lei, Yong

    2010-08-01

    The purpose of this study is to prepare 99mTc-HEDTMP [N-(2-hydroxyethyl) ethlenediamine-1,1,2-tri (methylene phosphonic acid), a new kind of bone seeking compound; to investigate its biological properties; and to explore the possibility of using it as a potential radiopharmaceutical for skeleton scintigraphy. HEDTMP was labeled with 99mTc by "pretinning" method, the radiochemical purity was 97.00% +/- 0.34%. 99mTc-HEDTMP was found to be stable in 5 hours in vitro with the radiochemical purity over 95% even after being diluted by physiological saline with the factor of dilution 100. The plane bone scanning of rabbits showed that 99mTc-HEDTMP was principally absorbed by skeletal system. Skull, spine and legs could be observed clearly, and were more legible than the images of 99mTc-MDP. Mice trial also indicated the high bone seeking of 99mTc-HEDTMP. The skeletal uptake was 11.92% ID/g, 13.19% ID/g, 10.14% ID/g, 10.04% ID/g, 7.71% ID/g separately at 30 minutes, 1 hour, 3 hours, 6 hours and 24 hours after the injection. Kidney seemed to be the major excretory organ. The clearance of blood was quick and the retaining amount in non-target organs was small. These results indicate that 99mTc-HEDTMP can be prepared easily, and its biological properties can be compared favorably with the commonly used bone imaging agent, and it is well worth further researching as a promising potential radiopharmaceutical in nuclide diagnosis for skeleton diseases. PMID:20842850

  17. Implementation and validation of collapsed cone superposition for radiopharmaceutical dosimetry of photon emitters

    NASA Astrophysics Data System (ADS)

    Sanchez-Garcia, Manuel; Gardin, Isabelle; Lebtahi, Rachida; Dieudonné, Arnaud

    2015-10-01

    Two collapsed cone (CC) superposition algorithms have been implemented for radiopharmaceutical dosimetry of photon emitters. The straight CC (SCC) superposition method uses a water energy deposition kernel (EDKw) for each electron, positron and photon components, while the primary and scatter CC (PSCC) superposition method uses different EDKw for primary and once-scattered photons. PSCC was implemented only for photons originating from the nucleus, precluding its application to positron emitters. EDKw are linearly scaled by radiological distance, taking into account tissue density heterogeneities. The implementation was tested on 100, 300 and 600 keV mono-energetic photons and 18F, 99mTc, 131I and 177Lu. The kernels were generated using the Monte Carlo codes MCNP and EGSnrc. The validation was performed on 6 phantoms representing interfaces between soft-tissues, lung and bone. The figures of merit were γ (3%, 3 mm) and γ (5%, 5 mm) criterions corresponding to the computation comparison on 80 absorbed doses (AD) points per phantom between Monte Carlo simulations and CC algorithms. PSCC gave better results than SCC for the lowest photon energy (100 keV). For the 3 isotopes computed with PSCC, the percentage of AD points satisfying the γ (5%, 5 mm) criterion was always over 99%. A still good but worse result was found with SCC, since at least 97% of AD-values verified the γ (5%, 5 mm) criterion, except a value of 57% for the 99mTc with the lung/bone interface. The CC superposition method for radiopharmaceutical dosimetry is a good alternative to Monte Carlo simulations while reducing computation complexity.

  18. A Treatment Planning Method for Sequentially Combining Radiopharmaceutical Therapy and External Radiation Therapy;External beam therapy; Radiopharmaceutical therapy; Three-dimensional dosimetry; Treatment planning

    SciTech Connect

    Hobbs, Robert F.; McNutt, Todd; Baechler, Sebastien; He Bin; Esaias, Caroline E.; Frey, Eric C.; Loeb, David M.; Wahl, Richard L.; Shokek, Ori; Sgouros, George

    2011-07-15

    Purpose: Effective cancer treatment generally requires combination therapy. The combination of external beam therapy (XRT) with radiopharmaceutical therapy (RPT) requires accurate three-dimensional dose calculations to avoid toxicity and evaluate efficacy. We have developed and tested a treatment planning method, using the patient-specific three-dimensional dosimetry package 3D-RD, for sequentially combined RPT/XRT therapy designed to limit toxicity to organs at risk. Methods and Materials: The biologic effective dose (BED) was used to translate voxelized RPT absorbed dose (D{sub RPT}) values into a normalized total dose (or equivalent 2-Gy-fraction XRT absorbed dose), NTD{sub RPT} map. The BED was calculated numerically using an algorithmic approach, which enabled a more accurate calculation of BED and NTD{sub RPT}. A treatment plan from the combined Samarium-153 and external beam was designed that would deliver a tumoricidal dose while delivering no more than 50 Gy of NTD{sub sum} to the spinal cord of a patient with a paraspinal tumor. Results: The average voxel NTD{sub RPT} to tumor from RPT was 22.6 Gy (range, 1-85 Gy); the maximum spinal cord voxel NTD{sub RPT} from RPT was 6.8 Gy. The combined therapy NTD{sub sum} to tumor was 71.5 Gy (range, 40-135 Gy) for a maximum voxel spinal cord NTD{sub sum} equal to the maximum tolerated dose of 50 Gy. Conclusions: A method that enables real-time treatment planning of combined RPT-XRT has been developed. By implementing a more generalized conversion between the dose values from the two modalities and an activity-based treatment of partial volume effects, the reliability of combination therapy treatment planning has been expanded.

  19. A new approach to the analysis of radiopharmaceuticals. Final technical report, January 15, 1987--June 30, 1991

    SciTech Connect

    Jones, A.G.; Davison, A.; Costello, C.E.

    1998-03-01

    The objective of this research was to investigate analytical techniques that could be used in the study of both the basic chemistry and the radiopharmaceutical chemistry of {sup 99m}Tc. First funded in 1981, the work focused initially upon the use of high performance liquid chromatography (HPLC) and various forms of mass spectrometry for the identification of technetium species. This funding allowed the authors to combine HPLC and mass spectrometry to identify radiopharmaceuticals which, although in clinical use, had not previously been characterized. Other techniques that have been examined include resonance Raman spectroscopy and, more significantly, {sup 99}Tc nuclear magnetic resonance spectroscopy (NMR), with the latter not only being used in purely chemical experiments but also in biologic studies. In 1985 a grant to the Department of Chemistry at MIT from DOE allowed the purchase of an X-ray diffractometer and access to this instrument has enabled them to broaden the analytical base with routine structural determinations.

  20. Production and Clinical Applications of Radiopharmaceuticals and Medical Radioisotopes in Iran.

    PubMed

    Jalilian, Amir Reza; Beiki, Davood; Hassanzadeh-Rad, Arman; Eftekhari, Arash; Geramifar, Parham; Eftekhari, Mohammad

    2016-07-01

    During past 3 decades, nuclear medicine has flourished as vibrant and independent medical specialty in Iran. Since that time, more than 200 nuclear physicians have been trained and now practicing in nearly 158 centers throughout the country. In the same period, Tc-99m generators and variety of cold kits for conventional nuclear medicine were locally produced for the first time. Local production has continued to mature in robust manner while fulfilling international standards. To meet the ever-growing demand at the national level and with international achievements in mind, work for production of other Tc-99m-based peptides such as ubiquicidin, bombesin, octreotide, and more recently a kit formulation for Tc-99m TRODAT-1 for clinical use was introduced. Other than the Tehran Research Reactor, the oldest facility active in production of medical radioisotopes, there is one commercial and three hospital-based cyclotrons currently operational in the country. I-131 has been one of the oldest radioisotope produced in Iran and traditionally used for treatment of thyrotoxicosis and differentiated thyroid carcinoma. Since 2009, (131)I-meta-iodobenzylguanidine has been locally available for diagnostic applications. Gallium-67 citrate, thallium-201 thallous chloride, and Indium-111 in the form of DTPA and Oxine are among the early cyclotron-produced tracers available in Iran for about 2 decades. Rb-81/Kr-81m generator has been available for pulmonary ventilation studies since 1996. Experimental production of PET radiopharmaceuticals began in 1998. This work has culminated with development and optimization of the high-scale production line of (18)F-FDG shortly after installation of PET/CT scanner in 2012. In the field of therapy, other than the use of old timers such as I-131 and different forms of P-32, there has been quite a significant advancement in production and application of therapeutic radiopharmaceuticals in recent years. Application of (131)I

  1. Cardiac blood-pool scintigraphy in rats and hamsters: comparison of five radiopharmaceuticals and three pinhole collimator apertures

    SciTech Connect

    Pieri, P.; Fischman, A.J.; Ahmad, M.; Moore, R.H.; Callahan, R.J.; Strauss, H.W. )

    1991-05-01

    Preclinical evaluation of cardiac drugs may require evaluation of cardiac function in intact animals. To optimize the quality of radionuclide measurements of ventricular function in small animals, a comparison was made of gated blood-pool scans recorded with five blood-pool radiopharmaceuticals ({sup 99}mTc-labeled human polyclonal IgG, {sup 99}mTc-human serum albumin labeled by two methods, and red blood cells radiolabeled with {sup 99}mTc via in vivo and in vitro methods) in rats and three pinhole apertures in hamsters. The quality of the radiopharmaceuticals was evaluated by comparing count density ratios (LV/BACKGROUND and LV/LIVER) and ejection fractions recorded with each agent. The edge definition of the left ventricle and count rate performance of the 1-, 2-, and 3-mm apertures was evaluated in hamsters. In general, the images obtained with the radiolabeled cells were superior to those obtained with the labeled proteins and no significant differences between the protein preparations were detected. Left ventricular ejection fractions calculated with all five radiopharmaceuticals were not significantly different. The best quality images were obtained with the 1-mm pinhole collimator. Ejection fraction and acquisition time were inversely related to aperture size. A good compromise between resolution and sensitivity was obtained with the 2-mm pinhole collimator.

  2. Development of more efficacious [Tc]-99m organ imaging agents for use in nuclear medicine by analytical characterization of radiopharmaceuticals

    SciTech Connect

    Heineman, W.R.

    1993-05-03

    This research program is detailed at development of more efficacious technetium-99m radiopharmaceuticals for use as imaging agents in diagnostic nuclear medicine. We seek to isolate and develop distinct site imaging agents to provide diagnostic information concerning a given pathological condition. Analytical techniques are being developed to enable complete analysis of radiopharmaceutical preparations so that individual complexes can be characterized with respect to imaging efficacy and to enable a radiopharmaceutical to be monitored after injection into a test animal to determine the species that actually accumulates in an organ to provide the image. Administration of the isolated, single most effective imaging complex, rather than a mixture of technetium-containing complexes, wi-11 minimize radiation exposure to the patient and maximize diagnostic information available to the clinician. This report specifically describes the development of capillary electrophoresis (CE) for characterizating diphosphonate skeletal imaging agents. Advances in the development of electrochemical and fiber optic sensors for Tc and Re imaging agents are described. These sensors will ultimately be capable of monitoring a specific chemical state of an imaging agent in vivo after injection into a test animal by implantation in the organ of interest.

  3. Gallium-68 DOTATATE Production with Automated PET Radiopharmaceutical Synthesis System: A Three Year Experience

    PubMed Central

    Aslani, Alireza; Snowdon, Graeme M; Bailey, Dale L; Schembri, Geoffrey P; Bailey, Elizabeth A; Roach, Paul J

    2014-01-01

    Objective(s): Gallium-68 (Ga-68) is an ideal research and hospital-based PET radioisotope. Currently, the main form of Ga-68 radiopharmaceutical that is being synthesised in-house is Ga-68 conjugated with DOTA based derivatives. The development of automated synthesis systems has increased the reliability, reproducibility and safety of radiopharmaceutical productions. Here we report on our three year, 500 syntheses experience with an automated system for Ga-68 DOTATATE. Methods: The automated synthesis system we use is divided into three parts of a) servomotor modules, b) single use sterile synthesis cassettes and, c) a computerised system that runs the modules. An audit trail is produced by the system as a requirement for GMP production. The required reagents and chemicals are made in-. The Germanium breakthrough is determined on a weekly basis. Production yields for each synthesis are calculated to monitor the performance and efficiency of the synthesis. The quality of the final product is assessed after each synthesis by ITLC-SG and HPLC methods. Results: A total of 500 Ga-68 DOTATATE syntheses (>800 patient doses) were performed between March 2011 and February 2014. The average generator yield was 81.3±0.2% for 2011, 76.7±0.4% for 2012 and 75.0±0.3% for 2013. Ga-68 DOTATATE yields for 2011, 2012, and 2013 were 81.8±0.4%, 82.2±0.4% and 87.9±0.4%, respectively. These exceed the manufacturer's expected value of approximately 70%. Germanium breakthrough averaged 8.6×10-6% of total activity which is well below the recommended level of 0.001%. The average ITLC-measured radiochemical purity was above 98.5% and the average HPLC-measured radiochemical purity was above 99.5%. Although there were some system failures during synthesis, there were only eight occasions where the patient scans needed to be rescheduled. Conclusion: In our experience the automated synthesis system performs reliably with a relatively low incident of failures. Our system had a consistent

  4. Study of potential utility of new radiopharmaceuticals based on technetium-99m labeled derivative of glucose

    NASA Astrophysics Data System (ADS)

    Zeltchan, R.; Medvedeva, A.; Sinilkin, I.; Chernov, V.; Stasyuk, E.; Rogov, A.; Il'ina, E.; Larionova, L.; Skuridin, V.

    2016-08-01

    Purpose: to study the potential utility of 1-thio-D-glucose labeled with 99mTc for cancer imaging in laboratory animals. Materials and method: the study was carried out in cell cultures of normal CHO (Chinese hamster ovary cells CHO) and malignant tissues MCF-7 (human breast adenocarcinoma MCF-7). To evaluate the uptake of 99mTc-1-thio-D-glucose in normal and tumor tissue cells, 25 MBq of 1-thio-D-glucose labeled with 99mTc was added to the vials with 3 million cells and incubated for 30 min at room temperature. After centrifugation of the vials with cells, the supernatant was removed. The radioactivity in vials with normal and tumor cells was then measured. In addition, the study included 40 mice of C57B1/6j lines with tumor lesion of the right femur. For neoplastic lesions, Lewis lung carcinoma model was used. Following anesthesia, mice were injected intravenously with 25 MBq of 99mTc-1-thio-D-glucose. Planar scintigraphy was performed 15 minutes later in a matrix of 512x512 pixels for 5 min. Results: when measuring the radioactivity of normal and malignant cells after incubation with 99mTc-1-thio-D-glucose, it was found that the radioactivity of malignant cells was higher than that of normal cells. The mean values of radioactivity levels in normal and malignant cells were 0.3 ± 0.15 MBq and 1.07 ± 0.6 MBq, respectively. All examined animals had increased accumulation of 99mTc-1-thio-D-glucose at the tumor site. The accumulation of 99mTc-1-thio-D-glucose in the tumor was on average twice as high as compared to the symmetric region. Conclusion: The present study demonstrated that 99mTc-1-thio-D-glucose is a prospective radiopharmaceutical for cancer visualization. In addition, high accumulation of 99mTc-1-thio-D-glucose in the culture of cancer cells and in tumor tissue of animals demonstrates tumor tropism of the radiopharmaceutical.

  5. Experimental study of radiopharmaceuticals based on technetium-99m labeled derivative of glucose for tumor diagnosis

    NASA Astrophysics Data System (ADS)

    Zeltchan, R.; Medvedeva, A.; Sinilkin, I.; Bragina, O.; Chernov, V.; Stasyuk, E.; Rogov, A.; Il'ina, E.; Larionova, L.; Skuridin, V.; Dergilev, A.

    2016-06-01

    Purpose: to study the potential utility of 1-thio-D-glucose labeled with 99mTc for cancer imaging in laboratory animals. Materials and method: the study was carried out in cell cultures of normal CHO (Chinese hamster ovary cells CHO) and malignant tissues MCF-7 (human breast adenocarcinoma MCF-7). To evaluate the uptake of 99mTc-1-thio-D-glucose in normal and tumor tissue cells, 25 MBq of 1-thio-D-glucose labeled with 99mTc was added to the vials with 3 million cells and incubated for 30 minutes at room temperature. After centrifugation of the vials with cells, the supernatant was removed. Radioactivity in vials with normal and tumor cells was then measured. In addition, the study included 40 mice of C57B 1/6j lines with tumor lesion of the right femur. For neoplastic lesions, Lewis lung carcinoma model was used. Following anesthesia, mice were injected intravenously with 25MBq of 99mTc-1-thio-D-glucose. Planar scintigraphy was performed 15 minutes later in a matrix of 512x512 pixels for 5 minutes. Results: when measuring the radioactivity of normal and malignant cells after incubation with 99mTc-1-thio-D- glucose, it was found that the radioactivity of malignant cells was higher than that of normal cells. The mean values of radioactivity levels in normal and malignant cells were 0.3±0.15MBq and 1.07±0.6MBq, respectively. All examined animals had increased accumulation of 99mTc-1-thio- D-glucose at the tumor site. The accumulation of 99mTc-1-thio-D-glucose in the tumor was on average twice as high as compared to the symmetric region. Conclusion: The present study demonstrated that 99mTc-1-thio-D-glucose is a prospective radiopharmaceutical for cancer visualization. In addition, high accumulation of 99mTc-1-thio-D-glucose in the culture of cancer cells and in tumor tissue of animals demonstrates tumor tropism of the radiopharmaceutical.

  6. Evaluation of H2CHXdedpa, H2dedpa- and H2CHXdedpa-N,N'-propyl-2-NI ligands for (64)Cu(ii) radiopharmaceuticals.

    PubMed

    Ramogida, Caterina F; Boros, Eszter; Patrick, Brian O; Zeisler, Stefan K; Kumlin, Joel; Adam, Michael J; Schaffer, Paul; Orvig, Chris

    2016-08-16

    The chiral acyclic "pa" ligand (pa = picolinic acid) H2CHXdedpa (N4O2) and two NI-containing dedpa analogues (H2CHXdedpa-N,N'-propyl-2-NI, H2dedpa-N,N'-propyl-2-NI, NI = nitroimidazole) were studied as chelators for copper radiopharmaceuticals (CHX = cyclohexyl, H2dedpa = 1,2-[[carboxypyridin-2-yl]methylamino]ethane). The hexadentate ligand H2CHXdedpa was previously established as a superb system for (67/68)Ga radiochemistry. The solid state X-ray crystal structures of [Cu(CHXdedpa-N,N'-propyl-2-NI)] and [Cu(dedpa-N,N'-propyl-2-NI)] reveal the predicted hexadentate, distorted octahedral binding of the copper(ii) ion. Cyclic voltammetry of [Cu(dedpa-N,N'-propyl-2-NI)] shows that there is one reversible couple associated with the NI redox, and one irreversible but reproducible couple attributed to the Cu(ii)/Cu(i) redox cycle. Quantitative radiolabeling (>99%) of CHXdedpa(2-) and (dedpa-N,N'-propyl-2-NI)(2-) with (64)Cu was achieved under fast and efficient labeling conditions (10 min, RT, 0.5 M sodium acetate buffer, pH 5.5) at ligand concentrations as low as 10(-6) M. In vitro kinetic inertness studies of the (64)Cu labelled complexes were studied in human serum at 37 °C over 24 hours; [(64)Cu(CHXdedpa)] was found to be 98% stable compared to previously investigated [(64)Cu(dedpa)] which was only 72% intact after 24 hours. PMID:27161975

  7. Sites and Mechanisms of Localization of Technetium-99m Phosphorus Radiopharmaceuticals in Acute Myocardial Infarcts and other Tissues

    PubMed Central

    Buja, L. Maximilian; Tofe, Andrew J.; Kulkarni, Padmakar V.; Mukherjee, Amal; Parkey, Robert W.; Francis, Marion D.; Bonte, Frederick J.; Willerson, James T.

    1977-01-01

    This study was performed to elucidate the localization at the cellular level of technetium-99m phosphorus (99mTc-P) radiopharmaceuticals in acute myocardial infarcts and the mechanisms responsible for 99mTc-P uptake in acute myocardial infarcts and other tissues. In 20 dogs with proximal left anterior descending coronary arterial ligation for 1-3 days, elevated calcium levels were measured at all sites of increased 99mTc-P uptake (acute myocardial infarcts, necrotic thoracotomy muscle, lactating breast, and normal bone); however, a consistent linear relationship between 99mTc-P and calcium levels was not observed. A strong correlation (r = 0.95 and 0.99, n = 2 dogs) was demonstrated between levels of 3H-diphosphonate and 99mTc-P in infarcted myocardium. Autoradiographic studies with 3H-diphosphonate revealed extensive labeling in the infarct periphery which contained necrotic muscle cells with features of severe calcium overloading, including widespread hypercontraction as well as more selective formation of mitochondrial calcific deposits. Autoradiography also demonstrated labeling of a small population of damaged border zone muscle cells which exhibited prominent accumulation of lipid droplets and focal, early mitochondrial calcification. Cell fractionation studies revealed major localization of both 99mTc-P and calcium in the soluble supernate and membrane-debris fractions of infarcted myocardium and less than 2% of total 99mTc-P and calcium in the mitochondrial fractions; however, electron microscopic examination showed that mitochondria with calcific deposits were not preserved in the mitochondrial fractions. In vitro studies evaluating the role of serum protein binding on tissue uptake of 99mTc-P agents demonstrated that, in spite of significant complexing with serum proteins, serum 99mTc-P activity retained the ability to adsorp to calcium hydroxyapatite and amorphous calcium phosphate. In vivo studies showed that concentration of human serum albumin

  8. Production of 64Cu and 67Cu radiopharmaceuticals using zinc target irradiated with accelerator neutrons

    NASA Astrophysics Data System (ADS)

    Kawabata, Masako; Hashimoto, Kazuyuki; Saeki, Hideya; Sato, Nozomi; Motoishi, Shoji; Nagai, Yasuki

    2014-09-01

    Copper radioisotopes have gained a lot of attention in radiopharmaceuticals owing to their unique decay characteristics. The longest half-life β emitter, 67Cu, is thought to be suitable for targeted radio-immunotherapy. Adequate production of 67Cu to meet the demands of clinical studies has not been fully established. Another attractive copper isotope, 64Cu has possible applications as a diagnostic imaging tracer combined with a therapeutic effect. This work proposes a production method using accelerator neutrons in which two copper radioisotopes can be produced: 1) 68Zn(n,x)67Cu and 2) 64Zn(n,p)64Cu using ~14 MeV neutrons generated by natC(d, n) reaction, both from natural or enriched zinc oxides. The generated 64,67Cu were separated from the target zinc oxide using a chelating and an anion exchange columns and were labelled with two widely studied chelators where the labelling efficiency was found to be acceptably good. The major advantage of this method is that a significant amount of 64,67Cu with a very few impurity radionuclides are produced which also makes the separation procedure simple. Provided an accelerator supplying an Ed = ~ 40 MeV, a wide application of 64,67Cu based drugs in nuclear medicine is feasible in the near future. We will present the characteristics of this production method using accelerator neutrons including the chemical separation processes.

  9. Laser stimulation of the acupoint 'Zusanli' (ST.36) on the radiopharmaceutical biodistribution in Wistar rats.

    PubMed

    Frederico, Éric H F F; Santos, Ailton A; Sá-Caputo, Danubia C C; Neves, Rosane F; Guimarães, Carlos A S; Chang, Shyang; Bernardo-Filho, Mario

    2016-03-01

    Laser used to stimulate acupoints is called laser acupuncture (LA). It is generally believed that similar clinical responses to manual acupuncture can be achieved. Here we analysed the effects of the laser (904 nm) at the 'Zusanli' acupoint (ST.36) of the stomach meridian on the biodistribution of the radiopharmaceutical Na(99m)TcO4. Wistar rats were divided into control (CG) and experimental groups (EG). The EG were exposed daily to the laser (904 nm) at ST.36 with 1 joule/min (40 mW/cm(2)) for 1 min. The animals of the CG were not exposed to laser at all. On the 8th day after LA, the animals were sedated and Na(99m)TcO4 was administered. After 10 min, the animals were all sacrificed and the organs removed. The radioactivity was counted in each organ to calculate the percentage of radioactivity of the injected dose per gram (%ATI/ g). Comparison of the %ATI/g in EG and CG was performed by Mann-Whitney test. The %ATI/g was significantly increased in the thyroid due to the stimulation of the ST.36 by laser. It is possible to conclude that the stimulation of ST.36 does lead to biological phenomena that interfere with the metabolism of the thyroid. PMID:26949088

  10. Development of radiodetection systems towards miniaturised quality control of PET and SPECT radiopharmaceuticals.

    PubMed

    Taggart, Matthew P; Tarn, Mark D; Esfahani, Mohammad M N; Schofield, Daniel M; Brown, Nathaniel J; Archibald, Stephen J; Deakin, Tom; Pamme, Nicole; Thompson, Lee F

    2016-04-26

    The ability to detect radiation in microfluidic devices is important for the on-chip analysis of radiopharmaceuticals, but previously reported systems have largely suffered from various limitations including cost, complexity of fabrication, and insufficient sensitivity and/or speed. Here, we present the use of sensitive, low cost, small-sized, commercially available silicon photomultipliers (SiPMs) for the detection of radioactivity inside microfluidic channels fabricated from a range of conventional microfluidic chip substrates. We demonstrate the effects of chip material and thickness on the detection of the positron-emitting isotope, [(18)F]fluoride, and find that, while the SiPMs are light sensors, they are able to detect radiation even through opaque chip materials via direct positron and gamma (γ) ray interaction. Finally, we employed the SiPM platform for analysis of the PET (positron emission tomography) radiotracers 2-[(18)F]fluoro-2-deoxy-d-glucose ([(18)F]FDG) and [(68)Ga]gallium-citrate, and highlight the ability to detect the γ ray emitting SPECT (single photon emission computed tomography) radiotracer, [(99m)Tc]pertechnetate. PMID:27044712

  11. PET radiopharmaceuticals for imaging of tumor hypoxia: a review of the evidence

    PubMed Central

    Lopci, Egesta; Grassi, Ilaria; Chiti, Arturo; Nanni, Cristina; Cicoria, Gianfranco; Toschi, Luca; Fonti, Cristina; Lodi, Filippo; Mattioli, Sandro; Fanti, Stefano

    2014-01-01

    Hypoxia is a pathological condition arising in living tissues when oxygen supply does not adequately cover the cellular metabolic demand. Detection of this phenomenon in tumors is of the utmost clinical relevance because tumor aggressiveness, metastatic spread, failure to achieve tumor control, increased rate of recurrence, and ultimate poor outcome are all associated with hypoxia. Consequently, in recent decades there has been increasing interest in developing methods for measurement of oxygen levels in tumors. Among the image-based modalities for hypoxia assessment, positron emission tomography (PET) is one of the most extensively investigated based on the various advantages it offers, i.e., broad range of radiopharmaceuticals, good intrinsic resolution, three-dimensional tumor representation, possibility of semiquantification/quantification of the amount of hypoxic tumor burden, overall patient friendliness, and ease of repetition. Compared with the other non-invasive techniques, the biggest advantage of PET imaging is that it offers the highest specificity for detection of hypoxic tissue. Starting with the 2-nitroimidazole family of compounds in the early 1980s, a great number of PET tracers have been developed for the identification of hypoxia in living tissue and solid tumors. This paper provides an overview of the principal PET tracers applied in cancer imaging of hypoxia and discusses in detail their advantages and pitfalls. PMID:24982822

  12. Technetium Tc-99m pyrophosphate for cerebrospinal fluid leaks: radiopharmaceutical considerations.

    PubMed

    Ponto, James A; Graham, Michael M

    2014-01-01

    OBJECTIVE To confirm the anticipated image quality and absence of adverse reactions in patients undergoing clinical practice cerebrospinal fluid (CSF) leak imaging procedures using technetium Tc-99m pyrophosphate (PYP). METHODS Following the recent discontinuation of preservative-free calcium trisodium diethylene triamine pentaacetic acid kits, PYP was selected as a suitable alternative for CSF leak imaging procedures. Procedures were established for its preparation and dispensing, paying special attention to safety considerations, and its use in clinical practice was implemented. Medical records, including images, were reviewed for the first 15 patients undergoing clinical practice CSF imaging procedures using Tc-99m PYP to confirm anticipated image quality and absence of adverse effects. RESULTS Review of CSF leak imaging procedures using Tc-99m PYP in 15 patients showed images to be of uniformly high quality. The vast majority of injected radiopharmaceutical remained in the CSF throughout the duration of the imaging procedure, allowing visualization of CSF leaks. Only a small amount of Tc-99m PYP diffused into the blood with resultant uptake on the skeleton and excretion into the urine, which did not interfere with image interpretation. No adverse reactions were noted in any of the patients. CONCLUSION With proper attention to safety considerations, Tc-99m PYP is a safe and effective alternative for performing CSF leak imaging procedures. PMID:24257695

  13. Multi-scale hybrid models for radiopharmaceutical dosimetry with Geant4.

    PubMed

    Marcatili, S; Villoing, D; Garcia, M P; Bardiès, M

    2014-12-21

    The accuracy of radiopharmaceutical absorbed dose distributions computed through Monte Carlo (MC) simulations is mostly limited by the low spatial resolution of 3D imaging techniques used to define the simulation geometry. This issue also persists with the implementation of realistic hybrid models built using polygonal mesh and/or NURBS as they require to be simulated in their voxel form in order to reduce computation times. The existing trade-off between voxel size and simulation speed leads on one side, in an overestimation of the size of small radiosensitive structures such as the skin or hollow organs walls and, on the other, to unnecessarily detailed voxelization of large, homogeneous structures.We developed a set of computational tools based on VTK and Geant4 in order to build multi-resolution organ models. Our aim is to use different voxel sizes to represent anatomical regions of different clinical relevance: the MC implementation of these models is expected to improve spatial resolution in specific anatomical structures without significantly affecting simulation speed. Here we present the tools developed through a proof of principle example. Our approach is validated against the standard Geant4 technique for the simulation of voxel geometries. PMID:25415621

  14. Uncertainty and sensitivity analysis of biokinetic models for radiopharmaceuticals used in nuclear medicine.

    PubMed

    Li, W B; Hoeschen, C

    2010-01-01

    Mathematical models for kinetics of radiopharmaceuticals in humans were developed and are used to estimate the radiation absorbed dose for patients in nuclear medicine by the International Commission on Radiological Protection and the Medical Internal Radiation Dose (MIRD) Committee. However, due to the fact that the residence times used were derived from different subjects, partially even with different ethnic backgrounds, a large variation in the model parameters propagates to a high uncertainty of the dose estimation. In this work, a method was developed for analysing the uncertainty and sensitivity of biokinetic models that are used to calculate the residence times. The biokinetic model of (18)F-FDG (FDG) developed by the MIRD Committee was analysed by this developed method. The sources of uncertainty of all model parameters were evaluated based on the experiments. The Latin hypercube sampling technique was used to sample the parameters for model input. Kinetic modelling of FDG in humans was performed. Sensitivity of model parameters was indicated by combining the model input and output, using regression and partial correlation analysis. The transfer rate parameter of plasma to other tissue fast is the parameter with the greatest influence on the residence time of plasma. Optimisation of biokinetic data acquisition in the clinical practice by exploitation of the sensitivity of model parameters obtained in this study is discussed. PMID:20185457

  15. Development of dopamine receptor radiopharmaceuticals for the study of neurological and psychiatric disorders

    SciTech Connect

    Dr. Jogeshwar Mukherjee

    2009-01-02

    Our goals in this grant application are directed towards the development of radiotracers that may allow the study of the high-affinity state (functional state) of the dopamine receptors. There have been numerous reports on the presence of two inter-convertible states of these (G-protein coupled) receptors in vitro. However, there is no report that establishes the presence of these separate affinity states in vivo. We have made efforts in this direction in order to provide such direct in vivo evidence about the presence of the high affinity state. This understanding of the functional state of the receptors is of critical significance in our overall diagnosis and treatment of diseases that implicate the G-protein coupled receptors. Four specific aims have been listed in the grant application: (1). Design and syntheses of agonists (2). Radiosyntheses of agonists (3). In vitro pharmacology of agonists (4). In vivo distribution and pharmacology of labeled derivatives. We have accomplished the syntheses and radiosyntheses of three agonist radiotracers labeled with carbon-11. In vitro and in vivo pharmacological experiments have been accomplished in rats and preliminary PET studies in non-human primates have been carried out. Various accomplishments during the funded years, briefly outlined in this document, have been disseminated by several publications in various journals and presentations in national and international meetings (Society of Nuclear Medicine, Society for Neuroscience and International Symposium on Radiopharmaceutical Chemistry).

  16. Multi-scale hybrid models for radiopharmaceutical dosimetry with Geant4

    NASA Astrophysics Data System (ADS)

    Marcatili, S.; Villoing, D.; Garcia, M. P.; Bardiès, M.

    2014-12-01

    The accuracy of radiopharmaceutical absorbed dose distributions computed through Monte Carlo (MC) simulations is mostly limited by the low spatial resolution of 3D imaging techniques used to define the simulation geometry. This issue also persists with the implementation of realistic hybrid models built using polygonal mesh and/or NURBS as they require to be simulated in their voxel form in order to reduce computation times. The existing trade-off between voxel size and simulation speed leads on one side, in an overestimation of the size of small radiosensitive structures such as the skin or hollow organs walls and, on the other, to unnecessarily detailed voxelization of large, homogeneous structures. We developed a set of computational tools based on VTK and Geant4 in order to build multi-resolution organ models. Our aim is to use different voxel sizes to represent anatomical regions of different clinical relevance: the MC implementation of these models is expected to improve spatial resolution in specific anatomical structures without significantly affecting simulation speed. Here we present the tools developed through a proof of principle example. Our approach is validated against the standard Geant4 technique for the simulation of voxel geometries.

  17. Complexation study on no-carrier-added astatine with insulin: a candidate radiopharmaceutical.

    PubMed

    Lahiri, Susanta; Roy, Kamalika; Sen, Souvik

    2008-12-01

    No-carrier-added astatine radionuclides produced in the (7)Li-irradiated lead matrix were separated from bulk lead nitrate target by complexing At with insulin, followed by dialysis. The method offers simultaneous separation of At from lead as well as its complexation with insulin. The At-insulin complex might be a potential radiopharmaceutical in the treatment of hepatocellular carcinoma. The stability of At-insulin complex was checked by dialysis against deionized water and Ringer lactate (RL) solution. It has been found that the half-life of At-insulin complex is about approximately 12h, when dialyzed against deionized water and is only 6h, when dialyzed against RL solution having the same composition as blood serum. The 6h half-life of this Insulin-At complex is perfect for killing cancer cells from external cell surfaces as the half-life of internalization of insulin molecule inside the cell is 7-12h. PMID:18674921

  18. Biokinetics and dosimetry of target-specific radiopharmaceuticals for molecular imaging and therapy

    NASA Astrophysics Data System (ADS)

    Ferro-Flores, Guillermina; Torres-García, Eugenio; Gonz&Ález-v&Ázquez, Armando; de Murphy, Consuelo Arteaga

    Molecular imaging techniques directly or indirectly monitor and record the spatiotemporal distribution of molecular or cellular processes for biochemical, biologic, diagnostic or therapeutic applications. 99mTc-HYNIC-TOC has shown high stability both in vitro and in vivo and rapid detection of somatostatin receptor-positive tumors. Therapies using radiolabeled anti-CD20 have demonstrated their efficacy in patients with B-cell non-Hodgkin's lymphoma (NHL). The aim of this study was to establish biokinetic models for 99mTc-HYNIC-TOC and 188Re-anti-CD20 and to evaluate their dosimetry as target-specific radiopharmaceuticals. The OLINDA/EXM code was used to calculate patient-specific internal radiation dose estimates. 99mTc-HYNIC-TOC images showed an average tumor/blood ratio of 4.3±0.7 in receptor-positive tumors with an average effective dose of 4.4 mSv. Dosimetric studies indicated that after administration of 5.8 to 7.5 GBq of 188Re-anti-CD20 the absorbed dose to total body would be 0.75 Gy which corresponds to the recommended dose for NHL therapies.

  19. A Concise Radiosynthesis of the Tau Radiopharmaceutical, [18F]T807

    PubMed Central

    Shoup, Timothy M.; Yokell, Daniel L.; Rice, Peter A.; Jackson, Raul N.; Livni, Eli; Johnson, Keith A.; Brady, Thomas J.; Vasdev, Neil

    2014-01-01

    Fluorine-18 labelled 7-(6-fluoropyridin-3-yl)-5H-pyrido[4,3-b]indole ([18F]T807) is a potent and selective agent for imaging paired helical filaments of tau (PHF-tau) and is among the most promising PET radiopharmaceuticals for this target in early clinical trials. The present study reports a simplified one-step method for the synthesis of [18F]T807 that is broadly applicable for routine clinical production using a GE Tracerlab™ FXFN radiosynthesis module. Key facets of our optimized radiosynthesis include development and use of a more soluble protected precursor, tert-butyl 7-(6-nitropyridin-3-yl)-5H-pyrido[4,3-b]indole-5-carboxylate, as well as new HPLC separation conditions that enable a facile one-step synthesis. During the nucleophilic fluorinating reaction with potassium cryptand [18F]fluoride (K[18F]/K222) in DMSO at 130 °C over 10 min, the precursor is concurrently deprotected. Formulated [18F]T807 was prepared in an uncorrected radiochemical yield of 14 ± 3%, with a specific activity of 216 ± 60 GBq/μmol (5837 ± 1621 mCi/μmol) at the end of synthesis (60 min; n = 3) and validated for human use. This methodology offers the advantage of faster synthesis in fewer steps, with simpler automation which we anticipate will facilitate widespread clinical use of [18F]T807. PMID:24339014

  20. A model of cellular dosimetry for macroscopic tumors in radiopharmaceutical therapy

    PubMed Central

    Hobbs, Robert F.; Baechler, Sébastien; Fu, De-Xue; Esaias, Caroline; Pomper, Martin G.; Ambinder, Richard F.; Sgouros, George

    2011-01-01

    Purpose: In the radiopharmaceutical therapy approach to the fight against cancer, in particular when it comes to translating laboratory results to the clinical setting, modeling has served as an invaluable tool for guidance and for understanding the processes operating at the cellular level and how these relate to macroscopic observables. Tumor control probability (TCP) is the dosimetric end point quantity of choice which relates to experimental and clinical data: it requires knowledge of individual cellular absorbed doses since it depends on the assessment of the treatment’s ability to kill each and every cell. Macroscopic tumors, seen in both clinical and experimental studies, contain too many cells to be modeled individually in Monte Carlo simulation; yet, in particular for low ratios of decays to cells, a cell-based model that does not smooth away statistical considerations associated with low activity is a necessity. The authors present here an adaptation of the simple sphere-based model from which cellular level dosimetry for macroscopic tumors and their end point quantities, such as TCP, may be extrapolated more reliably. Methods: Ten homogenous spheres representing tumors of different sizes were constructed in GEANT4. The radionuclide 131I was randomly allowed to decay for each model size and for seven different ratios of number of decays to number of cells, Nr: 1000, 500, 200, 100, 50, 20, and 10 decays per cell. The deposited energy was collected in radial bins and divided by the bin mass to obtain the average bin absorbed dose. To simulate a cellular model, the number of cells present in each bin was calculated and an absorbed dose attributed to each cell equal to the bin average absorbed dose with a randomly determined adjustment based on a Gaussian probability distribution with a width equal to the statistical uncertainty consistent with the ratio of decays to cells, i.e., equal to Nr-1∕2. From dose volume histograms the surviving fraction of cells

  1. Synthesis and radioiodination of ergoline derivatives: potential in-vivo dopamine receptor site mapping radiopharmaceuticals

    SciTech Connect

    Mikhail, E.A.

    1985-01-01

    The need of a dopamine-receptor based radiopharmaceutical for brain imaging is apparent. If such an agent is made available to physicians, it could provide means for detecting brain tumors, and diagnose such mental disorders as parkinsonism, schizophrenia and psychosis. Currently, such agents are yet to be discovered. Procedures were developed to synthesize and label four ergoline derivatives which could potentially exhibit affinity to dopamine receptors. Labelling with /sup 125/I was accomplished in some cases by displacing a suitably positioned leaving group with /sup 125/I-anion, while in other cases iodine exchange procedures were utilized. Formulations of the labeled derivatives were achieved via the formation of their water soluble tartarate salts. Biodistribution studies in mature Sprague-Dawley rats showed that of the four radioactive compounds injected, the highest uptake in the brain and adrenals was achieved with 8 ..beta..-(I-125)-iodomethyl-6-propylergoline. In addition, high target/nontarget ratios were obtained with the above mentioned compound. On the other hand, the least brain and adrenal uptake as well as the lowest target/nontarget ratios were exhibited by 8 ..beta..-(I-125)-(p-iodobenzenesulfonyl)-lysergol presumably due to its in-vivo instability. A comparative biodistribution study for ergoline derivatives and N-isopropyl-(I-123)-p-iodoamphetamine was conducted. The biodistribution studies showed that the brain to blood ratio for the ergoline derivative 8 ..beta..-(I-125)-iodomethyl-6-propylergoline to be very close to that for /sup 125/I-IMP at 1 minute after dose administration. However after 15 minutes the brain/blood ratio of compound XLVI was half the value of /sup 123/I-IMP. Different mechanisms of brain influx and efflux are known to occur with the amphetamine and ergoline derivatives.

  2. A concise radiosynthesis of the tau radiopharmaceutical, [(18) F]T807.

    PubMed

    Shoup, Timothy M; Yokell, Daniel L; Rice, Peter A; Jackson, Raul N; Livni, Eli; Johnson, Keith A; Brady, Thomas J; Vasdev, Neil

    2013-12-01

    Fluorine-18 labeled 7-(6-fluoropyridin-3-yl)-5H-pyrido[4,3-b]indole ([(18) F]T807) is a potent and selective agent for imaging paired helical filaments of tau and is among the most promising PET radiopharmaceuticals for this target in early clinical trials. The present study reports a simplified one-step method for the synthesis of [(18) F]T807 that is broadly applicable for routine clinical production using a GE TRACERlab™ FXFN radiosynthesis module. Key facets of our optimized radiosynthesis include development and use of a more soluble protected precursor, tert-butyl 7-(6-nitropyridin-3-yl)-5H-pyrido[4,3-b]indole-5-carboxylate, as well as new HPLC separation conditions that enable a facile one-step synthesis. During the nucleophilic fluorinating reaction with potassium cryptand [(18) F]fluoride (K[(18) F]/K222 ) in DMSO at 130 °C over 10 min the precursor is concurrently deprotected. Formulated [(18) F]T807 was prepared in an uncorrected radiochemical yield of 14 ± 3%, with a specific activity of 216 ± 60 GBq/µmol (5837 ± 1621 mCi/µmol) at the end of synthesis (60 min; n = 3) and validated for human use. This methodology offers the advantage of faster synthesis in fewer steps, with simpler automation that we anticipate will facilitate widespread clinical use of [(18) F]T807. PMID:24339014

  3. Integrating bone targeting radiopharmaceuticals into the management of patients with castrate-resistant prostate cancer with symptomatic bone metastases.

    PubMed

    Blacksburg, Seth R; Witten, Matthew R; Haas, Jonathan A

    2015-03-01

    Metastatic castrate-resistant prostate cancer (CRPC) refers to the disease state in which metastatic prostate cancer fails to respond to androgen deprivation therapy (ADT). This can be manifest as a rising PSA, increase in radiographically measurable disease, or progression of clinical disease. Roughly 90 % of men with metastatic prostate cancer have bone metastases, which is a predictor of both morbidity and mortality. Historically, treatment has been palliative, consisting of external beam radiation therapy (EBRT) and pharmacological analgesics for pain control and osteoclast inhibitors, such as bisphosphonates and denosumab to mitigate skeletal-related events. Older radiopharmaceuticals, such as Strontium-89 and Samarium-153, are Beta-emitting agents that were found to provide palliation but were without survival benefit and carried high risks of myelosuppression. Radium-223 is an Alpha-emitting radiopharmaceutical that has demonstrated a significant overall survival benefit in men with metastatic CRPC, delay to symptomatic skeletal events (SSEs), and improvement in pain control, with a favorable toxicity profile compared with placebo. Unlike EBRT, Radium-223 has systemic uptake, with the potential to address several bone metastases concurrently and provides overall survival benefit. It is a simple administration with minimal complexity and shielding requirements in experienced hands. EBRT appears to provide a more rapid and dramatic palliative benefit to any given lesion. Because Radium-223 has limited myelosuppression, the two can be thoughtfully integrated, along with multiple agents, for the treatment of men with CRPC with symptomatic bone metastases. Given its excellent safety profile, there is interest and anecdotal safety combining Radium-223 with therapies, such as abiraterone and enzalutamide. Formal recommendations regarding combination therapies will require clinical trials. The use of Alpha-emitting radiopharmaceuticals in castrate-sensitive disease

  4. 175Yb-TTHMP as a good candidate for bone pain palliation and substitute of other radiopharmaceuticals

    PubMed Central

    Safarzadeh, Laleh

    2014-01-01

    Bone metastasis is one of the most frequent causes of pain in cancer patients. Different radioisotopes such as P-32, Sm-153, Ho-166, Lu-177, and Re-186 with several chemical ligands as ethylenediaminetetramethylene phosphonic acid (EDTMP), 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetramethylene phosphonic acid (DOTMP), and propylenediaminetetramethylene phosphonate (PDTMP) are recommended for bone pain palliation. In this work, 175Yb-triethylenetetraminehexamethylene phosphonic acid (TTHMP) was produced as a proper alternative to other radiopharmaceuticals. Relatively long half-life (T1/2 = 4.18 days), maximum energy beta particle Eβ =470 keV (86.5%), low abundance gamma emission 396 keV (6.4%), 286 keV (3.01%), 113.8 keV (1.88%) and low cost are considered advantageous of Yb-175 are to wider usage of this isotope; in addition, TTHMP is an ideal carrier moiety for bone metastases. Production, quality control, and biodistribution studies of 175Yb-TTHMP were targeted. Yb-175 chloride was obtained by thermal neutron bombardment of a natural Yb2O3 sample at Tehran Research Reactor (TRR), radiolabeling was completed in 1 h by the addition of TTHMP at the room temperature and pH was 7.5-8, radiochemical purity was higher than 95%. Biodistribution studies in normal rats were carried out. The results showed favorable biodistribution features of 175Yb-TTHMP, indicating significant accumulation in bone tissues compared with clinically used bone-seeking radiopharmaceuticals. This research presents 175Yb-TTHMP can be a good candidate for bone pain palliation and substitute of other radiopharmaceuticals, however, further biological studies in other mammals are still needed. PMID:25210277

  5. Analysis of radionuclide concentration in air released through the stack of a radiopharmaceutical production facility based on a medical cyclotron

    NASA Astrophysics Data System (ADS)

    Giardina, M.; Tomarchio, E.; Greco, D.

    2015-11-01

    Positron emitting radionuclides are increasingly used in medical diagnostics and the number of radiopharmaceutical production facilities have been estimated to be growing worldwide. During the process of production and/or patient administration of radiopharmaceuticals, an amount of these radionuclides might become airborne and escape into the environment. Therefore, the analysis of radionuclide concentration in the air released to the stack is a very important issue to evaluate the dose to the population living around the plant. To this end, sampling and measurement of radionuclide concentration in air released through the stack of a Nuclear Medicine Center (NMC), provided with a cyclotron for radiopharmaceuticals production, must be routinely carried out with an automatic measurement system. In this work is presented the air monitoring system realized at "San Gaetano" NMC at Bagheria (Italy) besides the analysis of the recorded stack relesead air concentration data. Sampling of air was carried out continuously and gamma-ray spectrometric measurement are made on-line and for a short time by using a shielded Marinelli beaker filled with sampled air and a gamma detector. The use of this system allows to have 1440 values of air concentration per day from 2002, year of the start of operation with the cyclotron. Therefore, the concentration values are very many and an analysis software is needed to determine the dose to the population. A comparison with the results of a simulation code based on a Gaussian Plume air dispersion modelling allow us to confirm the no-radiological significance of the stack effluent releases in terms of dose to population and to evaluate possible improvements in the plant devices to reduce the air concentration at stack.

  6. Preclinical assessment of dopaminergic system in rats by MicroPET using three positron-emitting radiopharmaceuticals

    NASA Astrophysics Data System (ADS)

    Lara-Camacho, V. M.; Ávila-García, M. C.; Ávila-Rodríguez, M. A.

    2014-11-01

    Different diseases associated with dysfunction of dopaminergic system such as Parkinson, Alzheimer, and Schizophrenia are being widely studied with positron emission tomography (PET) which is a noninvasive method useful to assess the stage of these illnesses. In our facility we have recently implemented the production of [11C ]-DTBZ, [11C ]-RAC, and [18F ]-FDOPA, which are among the most common PET radiopharmaceuticals used in neurology applications to get information about the dopamine pathways. In this study two healthy rats were imaged with each of those radiotracers in order to confirm selective striatum uptake as a proof of principle before to release them for human use.

  7. Preclinical assessment of dopaminergic system in rats by MicroPET using three positron-emitting radiopharmaceuticals

    SciTech Connect

    Lara-Camacho, V. M. Ávila-García, M. C. Ávila-Rodríguez, M. A.

    2014-11-07

    Different diseases associated with dysfunction of dopaminergic system such as Parkinson, Alzheimer, and Schizophrenia are being widely studied with positron emission tomography (PET) which is a noninvasive method useful to assess the stage of these illnesses. In our facility we have recently implemented the production of [{sup 11}C]-DTBZ, [{sup 11}C]-RAC, and [{sup 18}F]-FDOPA, which are among the most common PET radiopharmaceuticals used in neurology applications to get information about the dopamine pathways. In this study two healthy rats were imaged with each of those radiotracers in order to confirm selective striatum uptake as a proof of principle before to release them for human use.

  8. A procedure for the standardization of gamma reference sources for quality assurance in activity measurements of radiopharmaceuticals.

    PubMed

    Oropesa, P; Serra, R; Gutiérrez, S; Hernández, A T

    2002-06-01

    A simplified procedure for the standardization of gamma reference sources, for use in quality assurance of activity measurements during production and application of radiopharmaceuticals in Cuban nuclear medicine laboratories, is described. The method is based on the reliable achievement of consistent measurements by both gamma-spectrometry and ionization chamber techniques, and allows to obtain reference sources with uncertainties lower than 2%. Experimental setup, validation procedure and typical results obtained for 99mTc, 131I, 201Tl and 153Sm are described and discussed. The method will serve also as a secondary reference system for radioactivity measurements in the country. PMID:12102334

  9. MIRD Pamphlet No. 26: Joint EANM/MIRD Guidelines for Quantitative 177Lu SPECT Applied for Dosimetry of Radiopharmaceutical Therapy.

    PubMed

    Ljungberg, Michael; Celler, Anna; Konijnenberg, Mark W; Eckerman, Keith F; Dewaraja, Yuni K; Sjögreen-Gleisner, Katarina; Bolch, Wesley E; Brill, A Bertrand; Fahey, Frederic; Fisher, Darrell R; Hobbs, Robert; Howell, Roger W; Meredith, Ruby F; Sgouros, George; Zanzonico, Pat; Bacher, Klaus; Chiesa, Carlo; Flux, Glenn; Lassmann, Michael; Strigari, Lidia; Walrand, Stephan

    2016-01-01

    The accuracy of absorbed dose calculations in personalized internal radionuclide therapy is directly related to the accuracy of the activity (or activity concentration) estimates obtained at each of the imaging time points. MIRD Pamphlet no. 23 presented a general overview of methods that are required for quantitative SPECT imaging. The present document is next in a series of isotope-specific guidelines and recommendations that follow the general information that was provided in MIRD 23. This paper focuses on (177)Lu (lutetium) and its application in radiopharmaceutical therapy. PMID:26471692

  10. Untangling the web of European regulations for the preparation of unlicensed radiopharmaceuticals: a concise overview and practical guidance for a risk-based approach.

    PubMed

    Lange, Rogier; ter Heine, Rob; Decristoforo, Clemens; Peñuelas, Iván; Elsinga, Philip H; van der Westerlaken, Monique M L; Hendrikse, N Harry

    2015-05-01

    Radiopharmaceuticals are highly regulated, because they are controlled both as regular medicinal products and as radioactive substances. This can pose a hurdle for their development and clinical use. Radiopharmaceuticals are fundamentally different from other medicinal products and these regulations are not always adequate for their production. Strict compliance may have a huge resource impact, without further improving product quality. In this paper we give an overview of the applicable legislation and guidelines and propose a risk-based approach for their implementation. We focus on a few controversial Good Manufacturing Practice topics: cleanroom classification, air pressure regime, cleanroom qualification and microbiological monitoring. We have developed an algorithm to assess the combined risk of microbiological contamination of a radiopharmaceutical preparation process and propose corresponding Good Manufacturing Practice classification levels. In our opinion, the risk of carry-over of radiopharmaceuticals by individuals cannot be contained by pressure differences, and complicated regimes with underpressured rooms are not necessary in most situations. We propose a sterility assurance level of 10 for radiopharmaceuticals that are administered within a working day, irrespective of their use. We suggest the adoption of limits for environmental monitoring of microbial contamination, as proposed by Bruel and colleagues, on behalf of the French Society of Radiopharmacy. Recently launched regulatory documents seem to breathe a more liberal spirit than current legislation and recognize the need for the use of risk assessment. We argue that future legislation be further harmonized and state risk assessment as the gold standard for implementation of drug quality regulations for the preparation of unlicensed radiopharmaceuticals. PMID:25646703

  11. Creation of ORNL NURBS-based phantoms: evaluation of the voxel effect on absorbed doses from radiopharmaceuticals.

    PubMed

    Gardumi, Anna; Farah, Jad; Desbrée, Aurélie

    2013-03-01

    Doses from radiopharmaceuticals absorbed by organs can be assessed using Monte Carlo simulations and computational phantoms. Patient-based voxel phantoms improve the realism of organ topology but present unrealistic stair-stepped surfaces. The goal of this research was to study the voxel effect on the basis of creation and voxelisation of a series of non-uniform rational B-spline (NURBS) reference phantoms issued from the publication of the Oak Ridge National Laboratory (ORNL). Absorbed doses from various radiopharmaceuticals were calculated and compared with the values obtained for the corresponding analytical phantoms for models of an adult male and a 5-y-old child. Dose differences lower than 12.5 % were observed when the critical structure of the skin was excluded. Moreover, the highest differences were noted for small organs and walls. Finally, all NURBS phantoms of the ORNL series, their voxelised version and the corresponding Monte Carlo N-Particle eXtended input files were programmed and are available for further simulations. PMID:22719045

  12. Radiation absorbed dose estimates for oxygen-15 radiopharmaceuticals (H2( V)O, C VO, O VO) in newborn infants

    SciTech Connect

    Powers, W.J.; Stabin, M.; Howse, D.; Eichling, J.O.; Herscovitch, P.

    1988-12-01

    In preparation for measurement of regional cerebral oxygen metabolism by positron emission tomography, radiation absorbed dose estimates for 19 internal organs, blood, and total body were calculated for newborn infants following bolus intravenous administration of H2( V)O and brief inhalation of C VO and O VO. Cumulated activity for each radiopharmaceutical was calculated from a compartmental model based on the known biologic behavior of the compound. Values for mean absorbed dose/unit cumulated activity (S) for internal organs and total body were based on a newborn phantom. S was separately calculated for blood. Total radiopharmaceutical absorbed dose estimates necessary to measure cerebral oxygen metabolism in a 3.51-kg infant based on 0.7 mCi/kg H2( V)O and 1 mCi/kg C VO and O VO were determined to be 1.6 rad to the lung (maximum organ dose), 0.28 rad to the marrow, 0.46 rad to the gonads, and 0.22 rad to total body. These values are similar to those for current clinical nuclear medicine procedures employing /sup 99m/Tc in newborn infants.

  13. [Extravasation of radiopharmaceuticals: preventive measures and management recommended by SoFRa (Société Française de Radiopharmacie)].

    PubMed

    Barré, E; Nguyen, M-L; Bruel, D; Fournel, C; Hosten, B; Lao, S; Vercellino, L; Rizzo-Padoin, N

    2013-07-01

    Radiopharmaceuticals extravasation is rare but may have serious clinical issues. Because no specific recommendations are being proposed to date, the goals of our working group created within the French Society of Radiopharmacy are to determine preventive measures and to establish a pragmatic management of extravasation of these drugs. Our preventive measures are to recognize the symptoms (erythema, venous discoloration, swelling), to know the risk factors (which are related to radiopharmaceutical, patient, site of injection, injection technique) and severity (from erythema to skin necrosis, depending on the radionuclide) and how to avoid them (training and awareness of staff, choice of injection site, route of drug administration test, use of a catheter for administration of therapeutic radiopharmaceuticals). Management should be immediate. It can be facilitated by a specific emergency kit. General measures recommended are the immediate cessation of injection, aspiration of fluid extravasation, delimitation of the extravasated area with an indelible pen, informing the doctor. Specific measures taking into account the radiotoxicity of the radionuclide and the type of radiopharmaceutical were also established. The patient should be informed by the doctor about the risks and how to take care of. Traceability of the incident must be ensured. A multidisciplinary reflexion is essential to manage the extravasation as early and effectively as possible. PMID:23835019

  14. Protein Binding Pocket Dynamics.

    PubMed

    Stank, Antonia; Kokh, Daria B; Fuller, Jonathan C; Wade, Rebecca C

    2016-05-17

    The dynamics of protein binding pockets are crucial for their interaction specificity. Structural flexibility allows proteins to adapt to their individual molecular binding partners and facilitates the binding process. This implies the necessity to consider protein internal motion in determining and predicting binding properties and in designing new binders. Although accounting for protein dynamics presents a challenge for computational approaches, it expands the structural and physicochemical space for compound design and thus offers the prospect of improved binding specificity and selectivity. A cavity on the surface or in the interior of a protein that possesses suitable properties for binding a ligand is usually referred to as a binding pocket. The set of amino acid residues around a binding pocket determines its physicochemical characteristics and, together with its shape and location in a protein, defines its functionality. Residues outside the binding site can also have a long-range effect on the properties of the binding pocket. Cavities with similar functionalities are often conserved across protein families. For example, enzyme active sites are usually concave surfaces that present amino acid residues in a suitable configuration for binding low molecular weight compounds. Macromolecular binding pockets, on the other hand, are located on the protein surface and are often shallower. The mobility of proteins allows the opening, closing, and adaptation of binding pockets to regulate binding processes and specific protein functionalities. For example, channels and tunnels can exist permanently or transiently to transport compounds to and from a binding site. The influence of protein flexibility on binding pockets can vary from small changes to an already existent pocket to the formation of a completely new pocket. Here, we review recent developments in computational methods to detect and define binding pockets and to study pocket dynamics. We introduce five

  15. Evolving nucleotide binding surfaces

    NASA Technical Reports Server (NTRS)

    Kieber-Emmons, T.; Rein, R.

    1981-01-01

    An analysis is presented of the stability and nature of binding of a nucleotide to several known dehydrogenases. The employed approach includes calculation of hydrophobic stabilization of the binding motif and its intermolecular interaction with the ligand. The evolutionary changes of the binding motif are studied by calculating the Euclidean deviation of the respective dehydrogenases. Attention is given to the possible structural elements involved in the origin of nucleotide recognition by non-coded primordial polypeptides.

  16. Design of site specific radiopharmaceuticals for tumor imaging. (Parts I and II)

    SciTech Connect

    Van Dort, M.E.

    1983-01-01

    Part I. Synthetic methods were developed for the preparation of several iodinated benzoic acid hydrazides as labeling moieties for indirect tagging of carbonyl-containing bio-molecules and potential tumor-imaging agents. Biodistribution studies conducted in mice on the derivatives having the I-125 label ortho to a phenolic OH demonstrated a rapid in vivo deiodination. Part II. The reported high melanin binding affinity of quinoline and other heterocyclic antimalarial drugs led to the development of many analogues of such molecules as potential melanoma-imaging agents. Once such analogue iodochloroquine does exhibit high melanin binding, but has found limited clinical use due to appreciable accumulation in non-target tissues such as the adrenal cortex and inner ear. This project developed a new series of candidate melanoma imaging agents which would be easier to radio-label, could yield higher specific activity product, and which might demonstrate more favorable pharmacokinetic and dosimetric characteristics compared to iodochloroquine.

  17. Phenylpiperazine-based radiopharmaceuticals for brain imaging. 3. Synthesis and evaluation of radioiodinated 1-alkyl-4-phenylpiperazines

    SciTech Connect

    Hanson, R.N.; Hassan, M.

    1987-01-01

    As part of our program in radiopharmaceutical chemistry we have prepared and evaluated a series of radioiodinated 1-alkyl-4-phenylpiperazines as potential brain-imaging agents. The compounds were chosen on the basis of their synthetic versatility, activation toward electrophilic substitution, and ease of purification. The intermediates 1-6 were readily obtained and converted to the corresponding radioiodinated products 7-12 in 76-91% isolated radiochemical yields. The tissue distribution in rats indicated that the 1-N-butyl derivative 9 possesses the best combination of brain uptake (0.28-0.35% ID X kg/g), retention, and selectivity (brain/blood greater than 20) over the 4-h evaluation period. A subsequent imaging and tissue distribution study in the dog using 131I-labeled 9 supported the results observed in the rat and suggested the potential of this agent as a brain-imaging agent.

  18. Studying the General Toxicity and Cumulative Properties of a Radiopharmaceutical Nanocolloid, (99m)Tc-Al2O3.

    PubMed

    Varlamova, N V; Churin, A A; Fomina, T I; Ermolaeva, L A; Vetoshkina, T V; Dubskaya, T Yu; Lamzina, T Yu; Fedorova, E P; Neupokoeva, O V; Skuridin, V S; Nesterov, E A; Larionova, L A; Chernov, V I

    2016-07-01

    We studied toxicity of a new Russian radiopharmaceutical Nanocolloid, (99m)Tc-Al2O3. Tests for acute toxicity showed that this agent belongs to a class of moderate-toxicity substances and does not have cumulative properties. The evaluation of subchronic toxicity after subcutaneous injection of this product to rats (0.04, 0.2, and 0.4 ml/kg) and rabbits (0.02 and 0.2 ml/kg) for 7 days did not reveal changes in the general state, temperature, body weight, indices of the peripheral blood and bone marrow, functions of the heart, liver, kidneys, and nervous system, and morphological characteristics of the internal organs in animals. The drug does not produce a local irritant effect. PMID:27502539

  19. Food and Drug Administration process for development and approval of drugs and radiopharmaceuticals: treatments in urologic oncology.

    PubMed

    Ning, Yang-Min; Maher, V Ellen

    2015-03-01

    Regulatory advice and assessment play an important role in the successful development of new drugs and radiopharmaceuticals for the treatment of urologic malignancies. Cooperation between the US Food and Drug Administration (FDA) and the pharmaceutical industry has led to the approval of more than 20 new urologic oncology products in the last 2 decades. Despite these advances, more effective treatments need to be developed and approved for the treatment of urologic malignancies. This review provides general information about the FDA's role in the development of investigational new drugs, with an emphasis on the regulatory process and the requirements for marketing approval. In addition, this review summarizes the products for the treatment of urologic malignancies that were approved by the FDA in the last 30 years and the key issues concerning urologic oncology products that were discussed publicly at Oncologic Drug Advisory Committee meetings in the past 10 years. PMID:25613202

  20. Performance of a Lanthanum Bromide Detector and a New Conception Collimator for Radiopharmaceuticals Molecular Imaging in Oncology

    NASA Astrophysics Data System (ADS)

    Pani, Roberto; Pellegrini, Rosanna; Bennati, Paolo; Cinti, Maria Nerina; Scafè, Raffaele; De Vincentis, Giuseppe; Navarria, Francesco; Moschini, Giuliano; Cencelli, Valentino Orsolini; De Notaristefani, Francesco; Rossi, Paolo

    2009-03-01

    We have realized and tested a new-design compact gamma camera for high resolution SPET (Single Photon Emission Tomography), and small animals' radio-pharmaceutical molecular imaging. The camera is based on a "continuous" Lanthanum tri-Bromide crystal, and a new Low Energy (LE) collimator. The crystal is interfaced to a 2×2 array of Hamamatsu-H8500 position sensitive photo-multipliers. The lead collimator features parallel hexagonal 1.0 mm holes, 18 mm length, 0.2 mm septa and 10×10 cm2 detection area. It was newly designed to fully exploit the high spatial resolution a Lanthanum crystal may provide. To better evaluate its role, we have compared our camera to three other systems with similar crystals and photomultipliers, but employing traditional collimators, either pinhole or parallel. The new camera seems to be complementary to pinhole systems and shows a very attractive trade-off between spatial resolution and detection area.

  1. Reproducibility of quantitative measures of binding potential in rat striatum: A test re-test study using DTBZ dynamic PET studies

    SciTech Connect

    Avendaño-Estrada, A. Lara-Camacho, V. M. Ávila-García, M. C. Ávila- Rodríguez, M. A.

    2014-11-07

    There is great interest in the study of dopamine (DA) pathways due to the increasing number of patients with illnesses related to the dopaminergic system and molecular imaging based in Positron Emission Tomography (PET) has been proven helpful for this task. Among the different radiopharmaceuticals available to study DA interaction, [{sup 11}C]Dihydrotetrabenazine (DTBZ) has a high affinity for the vesicular monoamine transporter type 2 (VMAT2) and its binding potential (BP) is a marker of DA terminal integrity. This paper reports on the intersubject reproducibility of BP measurements in rat striatum with [11C]DTBZ using the Logańs method.

  2. Coordination chemistry of the sup 212 Pb/ sup 212 Bi nuclear transformation: Alpha-emitting radiopharmaceuticals

    SciTech Connect

    Parks, N.J.; Harris, W.R.; Keen, C.L.; Cooper, S.R.

    1992-07-01

    Subdivisions of this project are: (a) the synthesis of prototypical thiolate and dithiocarbamate based hexacoordinate complexes, (b) radiochemical engineering for generation of no-carrier-added lead and bismuth radioelements, (c) the first isolation of bismuth-binding proteins from in vivo studies with cyclotron produced {sup 205/206}Bi tracer, and (d) initial development of transport mechanisms for the intracellular radiobiological study of alpha emitting bismuth, and (e) the initiation of chemical equilibrium studies and biochemical pathways with cyclotron-produced, no-carrier-added, {sup 203}Pb (T{sub 1/2} = 51 hr).

  3. Positron binding to molecules

    NASA Astrophysics Data System (ADS)

    Danielson, J. R.

    2011-05-01

    While there is theoretical evidence that positrons can bind to atoms, calculations for molecules are much less precise. Unfortunately, there have been no measurements of positron-atom binding, due primarily to the difficulty in forming positron-atom bound states in two-body collisions. In contrast, positrons attach to molecules via Feshbach resonances (VFR) in which a vibrational mode absorbs the excess energy. Using a high-resolution positron beam, this VFR process has been studied to measure binding energies for more than 40 molecules. New measurements will be described in two areas: positron binding to relatively simple molecules, for which theoretical calculations appear to be possible; and positron binding to molecules with large permanent dipole moments, which can be compared to analogous, weakly bound electron-molecule (negative-ion) states. Binding energies range from 75 meV for CS2 (no dipole moment) to 180 meV for acetonitrile (CH3CN). Other species studied include aldehydes and ketones, which have permanent dipole moments in the range 2.5 - 3.0 debye. The measured binding energies are surprisingly large (by a factor of 10 to 100) compared to those for the analogous negative ions, and these differences will be discussed. New theoretical calculations for positron-molecule binding are in progress, and a recent result for acetonitrile will be discussed. This ability to compare theory and experiment represents a significant step in attempts to understand positron binding to matter. In collaboration with A. C. L. Jones, J. J. Gosselin, and C. M. Surko, and supported by NSF grant PHY 07-55809.

  4. Metallochaperones: bind and deliver

    SciTech Connect

    Rosenzweig, A.C.

    2010-03-08

    Metallochaperones deliver metal ions directly to target proteins via specific protein-protein interactions. Recent research has led to a molecular picture of how some metallochaperones bind metal ions, recognize their partner proteins, and accomplish metal ion transfer.

  5. Comparison of effective dose and lifetime risk of cancer incidence of CT attenuation correction acquisitions and radiopharmaceutical administration for myocardial perfusion imaging

    PubMed Central

    Szczepura, K; Hogg, P

    2014-01-01

    Objective: To measure the organ dose and calculate effective dose from CT attenuation correction (CTAC) acquisitions from four commonly used gamma camera single photon emission CT/CT systems. Methods: CTAC dosimetry data was collected using thermoluminescent dosemeters on GE Healthcare's Infinia™ Hawkeye™ (GE Healthcare, Buckinghamshire, UK) four- and single-slice systems, Siemens Symbia™ T6 (Siemens Healthcare, Erlangen, Germany) and the Philips Precedence (Philips Healthcare, Amsterdam, Netherlands). Organ and effective dose from the administration of 99mTc-tetrofosmin and 99mTc-sestamibi were calculated using International Commission of Radiological Protection reports 80 and 106. Using these data, the lifetime biological risk was calculated. Results: The Siemens Symbia gave the lowest CTAC dose (1.8 mSv) followed by the GE Infinia Hawkeye single-slice (1.9 mSv), GE Infinia Hawkeye four-slice (2.5 mSv) and Philips Precedence v. 3.0. Doses were significantly lower than the calculated doses from radiopharmaceutical administration (11 and 14 mSv for 99mTc-tetrofosmin and 99mTc-sestamibi, respectively). Overall lifetime biological risks were lower, which suggests that using CTAC data posed minimal risk to the patient. Comparison of data for breast tissue demonstrated a higher risk than that from the radiopharmaceutical administration. Conclusion: CTAC doses were confirmed to be much lower than those from radiopharmaceutical administration. The localized nature of the CTAC exposure compared to the radiopharmaceutical biological distribution indicated dose and risk to the breast to be higher. Advances in knowledge: This research proved that CTAC is a comparatively low-dose acquisition. However, it has been shown that there is increased risk for breast tissue especially in the younger patients. As per legislation, justification is required and CTAC should only be used in situations that demonstrate sufficient net benefit. PMID:24998249

  6. A simple low-cost of liquid I-131 dispenser for routine radiopharmaceutical dispensing at nuclear medicine department, Institut Kanser Negara

    NASA Astrophysics Data System (ADS)

    Said, M. A.; Ashhar, Z. N.; Suhaimi, N. E. F.; Zainon, R.

    2016-01-01

    In routine radiopharmaceutical Iodine-131 (131I) dispensing, the amount of radiation dose received by the personnel depends on the distance between the personnel and the source, the time spent manipulating the source and the amount of shielding used to reduce the dose rate from the source. The novel iRAD-I131 dispenser using recycle 131I liquid lead pot will lead into low cost production, less maintenance and low dose received by the personnel that prepared the 131I. The new fabricated of low cost 131I dispenser was tested and the dose received by personnel were evaluated. The body of lead material is made from 2.5 cm lead shielded coated with epoxy paint to absorb the radiation dose up to 7.4 GBq of 131 I. The lead pot was supported with two stainless steel rod. The Optically Stimulated Luminescence (OSL) nanodot was used in this study to measure the dose rate at both extremities for every personnel who prepared the 131I. Each OSL nanodot was attached at the fingertip. Three different personnel (experienced between one to ten years above in preparing the radiopharmaceuticals) were participated in this study. The average equivalent dose at right and left hand were 122.694 ± 121.637 µSv/GBq and 77.281 ± 62.146 µSv/GBq respectively. This study found that the dose exposure received using iRAD-I131 was less up to seven times compared to the conventional method. The comparison of experimental data using iRAD-I131 and established radiopharmaceutical dispenser was also discussed. The innovation of 131I dispenser is highly recommended in a small radiopharmaceutical facility with limited budget. The novel iRAD-I131 enables implementation of higher output liquid dispensing with low radiation dose to the personnel.

  7. Molecular modeling in the development of metal radiopharmaceuticals. Final progress report, July 15, 1989--July 14, 1993

    SciTech Connect

    Green, M.A.

    1993-10-01

    We began this project with a compilation of a structural library to serve as a data base containing descriptions of the molecular features of metal-labeled radiopharmaceuticals known to efficiently cross the blood-brain barrier. Such a data base is needed in order to identify structural features (size, shape, molecular surface areas and volumes) that are critical in allowing blood-brain barrier penetration. Nine metal complexes have been added to this structural library. We have completed a detailed comparison of four molecular mechanics computer programs QUANTA, SYBYL, BOYD, and MM2DREW to assess their applicability to modeling the structures of low molecular weight metal complexes. We tested the ability of each program to reproduce the crystallographic structures of 38 complexes between nickel(II) and saturated N-donor ligands. The programs were evaluated in terns of their ability to reproduce structural features such as bond lengths, bond angles, and torsion angles. Recently, we investigated the synthesis and characterization of lipophilic cationic gallium complexes with hexadentate bis(salicylaldimine) ligands. This work identified the first gallium-68 radiopharrnaceuticals that can be injected intravenously and that subsequently exhibit significant myocardial uptake followed by prolonged myocardial retention of {sup 68}Ga radioactivity. Tracers of this type remain under investigation as agents for evaluation of myocardial perfusion with positron emission tomography.

  8. Skin dose rate conversion factors after contamination with radiopharmaceuticals: influence of contamination area, epidermal thickness and percutaneous absorption.

    PubMed

    Covens, P; Berus, D; Caveliers, V; Struelens, L; Vanhavere, F; Verellen, D

    2013-06-01

    Skin contamination with radiopharmaceuticals can occur during biomedical research and daily nuclear medicine practice as a result of accidental spills, after contact with bodily fluids of patients or by inattentively touching contaminated materials. Skin dose assessment should be carried out by repeated quantification to map the course of the contamination together with the use of appropriate skin dose rate conversion factors. Contamination is generally characterised by local spots on the palmar surface of the hand and complete decontamination is difficult as a result of percutaneous absorption. This specific issue requires special consideration as to the skin dose rate conversion factors as a measure for the absorbed dose rate to the basal layer of the epidermis. In this work we used Monte Carlo simulations to study the influence of the contamination area, the epidermal thickness and the percutaneous absorption on the absorbed skin dose rate conversion factors for a set of 39 medical radionuclides. The results show that the absorbed dose to the basal layer of the epidermis can differ by up to two orders of magnitude from the operational quantity Hp(0.07) when using an appropriate epidermal thickness in combination with the effect of percutaneous absorption. PMID:23519114

  9. Bone-seeking radiopharmaceuticals for treatment of osseous metastases, Part 1: α therapy with 223Ra-dichloride.

    PubMed

    Pandit-Taskar, Neeta; Larson, Steven M; Carrasquillo, Jorge A

    2014-02-01

    Metastatic disease to bone is commonly seen in the advanced stages of many cancers. The cardinal symptom, pain, is often the cause of significant morbidity and reduced quality of life. Treatment of bone pain includes nonsteroidal analgesics and opiates; however, long-term use of these drugs is commonly associated with significant side effects, and tolerance is common. External-beam radiation therapy is effective mainly in localized disease sites. Bone-targeting radiopharmaceuticals are beneficial in the management of patients with multiple metastatic lesions. This article focuses on the 3 most commonly used agents: the Food and Drug Administration-approved (89)Sr-chloride, (153)Sm-ethylenediaminetetramethylene phosphonic acid (EDTMP), and (223)Ra-dichloride. We will discuss the physical characteristics, clinical data, dosage, and administration of these agents, including optimal patient selection and toxicity associated with their use. These radioactive agents have proven efficacy in the treatment of painful osseous metastases from prostate cancer and breast cancer. Significant recent advances include use of these agents in combination with chemotherapy and the use of the α emitter (223)Ra-dichloride in prostate cancer, primarily to improve survival and skeletal related events. The review is presented in 2 parts. The first will discuss the characteristics and clinical use of (223)Ra-dichloride, and the second will discuss the β emitters (89)Sr and (153)Sm-EDTMP. PMID:24343987

  10. SU-C-303-03: Dosimetric Model of the Beagle Needed for Pre-Clinical Testing of Radiopharmaceuticals

    SciTech Connect

    Shang, M; Sands, M; Bolch, W

    2015-06-15

    Purpose: Large animal models, most popularly beagles, have been crucial surrogates to humans in determining radiation safety levels of radiopharmaceuticals. This study aims to develop a detailed beagle phantom to accurately approximate organ absorbed doses for therapy nuclear medicine preclinical studies. Methods: A 3D NURBS model was created subordinate to a whole body CT of an adult beagle. Bones were harvested and CT imaged to offer macroscopic skeletal detail. Samples of trabecular spongiosa were cored and imaged to offer microscopic skeletal detail for bone trabeculae and marrow volume fractions. Results: Organ masses in the model are typical of an adult beagle. Trends in volume fractions for skeletal dosimetry are fundamentally similar to those found in existing models of other canine species. Conclusion: This work warrants its use in further investigations of radiation transport calculation for electron and photon dosimetry. This model accurately represents the anatomy of a beagle, and can be directly translated into a useable geometry for a voxel-based Monte Carlo radiation transport program such as MCNP6. Work supported by a grant from the Hyundai Hope on Wheels Foundation for Pediatric Cancer Research.

  11. (11)C[double bond, length as m-dash]O bonds made easily for positron emission tomography radiopharmaceuticals.

    PubMed

    Rotstein, Benjamin H; Liang, Steven H; Placzek, Michael S; Hooker, Jacob M; Gee, Antony D; Dollé, Frédéric; Wilson, Alan A; Vasdev, Neil

    2016-08-22

    The positron-emitting radionuclide carbon-11 ((11)C, t1/2 = 20.3 min) possesses the unique potential for radiolabeling of any biological, naturally occurring, or synthetic organic molecule for in vivo positron emission tomography (PET) imaging. Carbon-11 is most often incorporated into small molecules by methylation of alcohol, thiol, amine or carboxylic acid precursors using [(11)C]methyl iodide or [(11)C]methyl triflate (generated from [(11)C]carbon dioxide or [(11)C]methane). Consequently, small molecules that lack an easily substituted (11)C-methyl group are often considered to have non-obvious strategies for radiolabeling and require a more customized approach. [(11)C]Carbon dioxide itself, [(11)C]carbon monoxide, [(11)C]cyanide, and [(11)C]phosgene represent alternative reactants to enable (11)C-carbonylation. Methodologies developed for preparation of (11)C-carbonyl groups have had a tremendous impact on the development of novel PET tracers and provided key tools for clinical research. (11)C-Carbonyl radiopharmaceuticals based on labeled carboxylic acids, amides, carbamates and ureas now account for a substantial number of important imaging agents that have seen translation to higher species and clinical research of previously inaccessible targets, which is a testament to the creativity, utility and practicality of the underlying radiochemistry. PMID:27276357

  12. Preparation and biological evaluation of (99m)Tc-ropinirole as a novel radiopharmaceutical for brain imaging.

    PubMed

    Motaleb, M A; Ibrahem, I T; Ayoub, V R; Geneidi, A S

    2016-04-01

    Noninvasive brain imaging is a process that allows scientists and physicians to view and monitor the areas of the brain. The aim of this study was to formulate a novel radiopharmaceutical for the detection of brain disorders at early stages in susceptible patients. (99m) Tc-ropinirole was prepared by the direct complexation of ropinirole with technetium-99m. The results showed that the radiochemical yield (99m) Tc-ropinirole was 92 ± 2.87% and the radiochemical yield was evaluated by paper chromatography and HPLC. In vitro studies showed that the formed complex was stable for up to 6 h. In vivo uptake of (99m) Tc-ropinirole in the brain was 4.87 ± 0.15% injected dose/g organ at 30 min post-injection, which cleared from the brain with time till it reaches 2.3% at 2 h post-injection indicating that the brain uptake of (99m) Tc-ropinirole is higher than that of the commercially available (99m) Tc-HMPAO, which is 2.25% at 30 min. Pre-dosing mice with cold ropinirole reduced the brain uptake to 0.26 ± 0.01% injected dose/g organ, so this confirms the high specificity and selectivity of this radiotracer for the assessment of the dopamine receptors. PMID:26913705

  13. New pathways to medicare coverage for innovative PET radiopharmaceuticals: report of a Medical Imaging & Technology Alliance (MITA) workshop.

    PubMed

    Hillman, Bruce J; Frank, Richard A; Rodriguez, Gail M

    2012-02-01

    PET and PET/CT have revolutionized the diagnosis, staging, and monitoring of treatment effect or recurrence for a wide range of cancers and shown promise for improving health outcomes for patients with cardiovascular and central nervous system diseases. However, this technology is challenged by insurance coverage policies that hinder patients' access to PET and discourage technologic innovation. Recently, the Medical Imaging & Technology Alliance (MITA), a Washington-based industry association, convened a workshop to consider new pathways for making decisions on Medicare coverage of new PET radiopharmaceuticals and imaging procedures that are currently subject to a national noncoverage decision, or "exclusionary rule." Stakeholders from the government, medical professional societies, academia, patient groups, and industry gathered to brainstorm alternatives to the national noncoverage decision and evaluate their potential to improve access and enhance innovation. Ultimately, MITA, on behalf of the PET community, expects to use the outcomes of the workshop to propose that the Centers for Medicare and Medicaid Services reconsider this current national noncoverage decision for PET and adopt a new framework for coverage. PMID:22192574

  14. New pathways to medicare coverage for innovative PET radiopharmaceuticals: report of a medical imaging & technology alliance (MITA) workshop.

    PubMed

    Hillman, Bruce J; Frank, Richard A; Rodriguez, Gail M

    2012-02-01

    PET and PET/CT have revolutionized the diagnosis, staging, and monitoring of treatment effect or recurrence for a wide range of cancers and shown promise for improving health outcomes for patients with cardiovascular and central nervous system diseases. However, this technology is challenged by insurance coverage policies that hinder patients' access to PET and discourage technologic innovation. Recently, the Medical Imaging & Technology Alliance (MITA), a Washington-based industry association, convened a workshop to consider new pathways for making decisions on Medicare coverage of new PET radiopharmaceuticals and imaging procedures that are currently subject to a national noncoverage decision, or "exclusionary rule." Stakeholders from the government, medical professional societies, academia, patient groups, and industry gathered to brainstorm alternatives to the national noncoverage decision and evaluate their potential to improve access and enhance innovation. Ultimately, MITA, on behalf of the PET community, expects to use the outcomes of the workshop to propose that the Centers for Medicare and Medicaid Services reconsider this current national noncoverage decision for PET and adopt a new framework for coverage. PMID:22178626

  15. Zebularine significantly sensitises MEC1 cells to external irradiation and radiopharmaceutical therapy when administered sequentially in vitro.

    PubMed

    Bryan, Jeffrey N; Kumar, Senthil R; Jia, Fang; Balkin, Ethan R; Lewis, Michael R

    2014-02-01

    Zebularine is a cytidine analogue incorporated into DNA during replication, inhibiting DNA methyltransferase 1 (DNMT1), resulting in demethylation and changes in gene expression. Such modification may improve radiosensitivity in resistant lymphoma cells. The hypothesis of this study was that zebularine and radiation would synergistically inhibit cell growth and viability. Human MEC1 malignant B cells were incubated with 0-200 µM zebularine for 48 h. Media containing zebularine was removed, and the cells were irradiated with 0-2 Gy of either external beam irradiation or (177) Lu-DOTA-TATE, a radiolabelled somatostatin analogue. Concentration and viability were measured over 48-72 h. The proportion of apoptotic cells was identified using an active Caspase 3/7 assay. Zebularine inhibited growth of cells in a dose-dependent manner during exposure. No residual growth inhibition occurred following removal of the drug. Zebularine and external irradiation inhibited cell proliferation in a dose-dependent, synergistic interaction, but the effect on viability was additive. Treatment with zebularine and (177) Lu-DOTA-TATE resulted in less inhibition of proliferation (P = 0.0135), but a synergistic decrease in viability. Apoptotic fraction was much higher in cells irradiated with (177) Lu-DOTA-TATE than external irradiation. External irradiation induces growth arrest rather than apoptosis. Apoptosis is the primary effect of radiopharmaceutical therapy on tumour cells. Treatment with the methylation inhibitor, zebularine, appears to synergistically augment these natural effects in vitro, which could be exploited clinically. PMID:24323360

  16. Zebularine Significantly Sensitizes MEC1 cells to External Irradiation and Radiopharmaceutical Therapy When Administered Sequentially in Vitro

    PubMed Central

    Bryan, Jeffrey N.; Kumar, Senthil R.; Jia, Fang; Balkin, Ethan R.; Lewis, Michael R.

    2014-01-01

    Zebularine is a cytidine analog incorporated into DNA during replication, inhibiting DNA methyltransferase 1 (DNMT1), resulting in demethylation and changes in gene expression. Such modification may improve radiosensitivity in resistant lymphoma cells. The hypothesis of this study was that zebularine and radiation would synergistically inhibit cell growth and viability. Human MEC1 malignant B cells were incubated with 0–200μM zebularine for 48h. Media containing zebularine was removed, and the cells were irradiated with 0–2 Gy of either external beam irradiation or 177Lu-DOTA-TATE, a radiolabeled somatostatin analogue. Concentration and viability were measured over 48-72h. The proportion of apoptotic cells was identified using an active Caspase 3/7 assay. Zebularine inhibited growth of cells in a dose-dependent manner during exposure. No residual growth inhibition occurred following removal of the drug. Zebularine and external irradiation inhibited cell proliferation in a dose-dependent, synergistic interaction, but the effect on viability was additive. Treatment with zebularine and 177Lu-DOTA-TATE resulted in less inhibition of proliferation (P=0.0135), but a synergistic decrease in viability. Apoptotic fraction was much higher in cells irradiated with 177Lu-DOTA-TATE than external irradiation. External irradiation arrests growth arrest rather than apoptosis. Apoptosis is the primary effect of radiopharmaceutical therapy on tumor cells. Treatment with the methylation inhibitor, zebularine, appears to synergistically augment these natural effects in vitro, which could be exploited clinically. PMID:24323360

  17. Single vial kit formulation of DOTATATE for preparation of (177) Lu-labeled therapeutic radiopharmaceutical at hospital radiopharmacy.

    PubMed

    Mukherjee, Archana; Lohar, Sharad; Dash, Ashutosh; Sarma, Haladhar Dev; Samuel, Grace; Korde, Aruna

    2015-04-01

    The clinical applications of radiolabeled somatostatin analogue (177) Lu-DOTA-Tyr(3) -Thr(8) -Octreotide ((177) Lu-DOTATATE) constitute a promising treatment option for patients with disseminated and inoperable neuroendocrine (NET) tumors. Formulation of (177) Lu-DOTATATE in hospital radiopharmacy under aseptic conditions in a safe and reliable manner is a major constraint for its extensive use. The present work was intended to develop a kit for the safe preparation of the therapeutic radiopharmaceutical, viz. (177) Lu-DOTATATE of high quality that can be easily adapted at conventional hospital radiopharmacies. Single vial kits of DOTATATE were formulated and evaluated for suitability for radiolabeling as well as stability on its storage. Patient dose of (177) Lu-DOTATATE (7.4 GBq) could be successfully prepared using semi-automated in-house setup that assures safe handling and high yields of product of pharmaceutical purity suitable for clinical use. Fast clearance of activity via renal route was observed in preclinical biodistribution studies of (177) Lu-DOTATATE carried out in normal Swiss mice. Deployment of in-house produced (177) LuCl3 , cold kits and easy adaptability of synthesis setup at hospital radiopharmacy for preparation is likely to expand applications of peptide receptor radionuclide therapy. PMID:25765604

  18. Inhibition of selectin binding

    DOEpatents

    Nagy, Jon O.; Spevak, Wayne R.; Dasgupta, Falguni; Bertozzi, Caroline

    1999-01-01

    This invention provides compositions for inhibiting the binding between two cells, one expressing P- or L-selectin on the surface and the other expressing the corresponding ligand. A covalently crosslinked lipid composition is prepared having saccharides and acidic group on separate lipids. The composition is then interposed between the cells so as to inhibit binding. Inhibition can be achieved at an effective oligosaccharide concentration as low as 10.sup.6 fold below that of the free saccharide. Since selectins are involved in recruiting cells to sites of injury, these composition scan be used to palliate certain inflammatory and immunological conditions.

  19. Inhibition of selectin binding

    DOEpatents

    Nagy, Jon O.; Spevak, Wayne R.; Dasgupta, Falguni; Bertozzi, Carolyn

    1999-10-05

    This invention provides a system for inhibiting the binding between two cells, one expressing P- or L-selectin on the surface and the other expressing the corresponding ligand. A covalently crosslinked lipid composition is prepared having saccharides and acidic group on separate lipids. The composition is then interposed between the cells so as to inhibit binding. Inhibition can be achieved at an effective oligosaccharide concentration as low as 10.sup.6 fold below that of the free saccharide. Since selectins are involved in recruiting cells to sites of injury, this system can be used to palliate certain inflammatory and immunological conditions.

  20. Inhibition of selectin binding

    DOEpatents

    Nagy, Jon O.; Spevak, Wayne R.; Dasgupta, Falguni; Bertozzi, Caroline

    2001-10-09

    This invention provides compositions for inhibiting the binding between two cells, one expressing P- or L-selectin on the surface and the other expressing the corresponding ligand. A covalently crosslinked lipid composition is prepared having saccharides and acidic group on separate lipids. The composition is then interposed between the cells so as to inhibit binding. Inhibition can be achieved at an effective oligosaccharide concentration as low as 10.sup.6 fold below that of the free saccharide. Since selectins are involved in recruiting cells to sites of injury, these composition scan be used to palliate certain inflammatory and immunological conditions.

  1. Cellulose binding domain proteins

    DOEpatents

    Shoseyov, O.; Shpiegl, I.; Goldstein, M.; Doi, R.

    1998-11-17

    A cellulose binding domain (CBD) having a high affinity for crystalline cellulose and chitin is disclosed, along with methods for the molecular cloning and recombinant production. Fusion products comprising the CBD and a second protein are likewise described. A wide range of applications are contemplated for both the CBD and the fusion products, including drug delivery, affinity separations, and diagnostic techniques. 16 figs.

  2. Cellulose binding domain proteins

    DOEpatents

    Shoseyov, Oded; Shpiegl, Itai; Goldstein, Marc; Doi, Roy

    1998-01-01

    A cellulose binding domain (CBD) having a high affinity for crystalline cellulose and chitin is disclosed, along with methods for the molecular cloning and recombinant production thereof. Fusion products comprising the CBD and a second protein are likewise described. A wide range of applications are contemplated for both the CBD and the fusion products, including drug delivery, affinity separations, and diagnostic techniques.

  3. MD-2 binds cholesterol.

    PubMed

    Choi, Soo-Ho; Kim, Jungsu; Gonen, Ayelet; Viriyakosol, Suganya; Miller, Yury I

    2016-02-19

    Cholesterol is a structural component of cellular membranes, which is transported from liver to peripheral cells in the form of cholesterol esters (CE), residing in the hydrophobic core of low-density lipoprotein. Oxidized CE (OxCE) is often found in plasma and in atherosclerotic lesions of subjects with cardiovascular disease. Our earlier studies have demonstrated that OxCE activates inflammatory responses in macrophages via toll-like receptor-4 (TLR4). Here we demonstrate that cholesterol binds to myeloid differentiation-2 (MD-2), a TLR4 ancillary molecule, which is a binding receptor for bacterial lipopolysaccharide (LPS) and is indispensable for LPS-induced TLR4 dimerization and signaling. Cholesterol binding to MD-2 was competed by LPS and by OxCE-modified BSA. Furthermore, soluble MD-2 in human plasma and MD-2 in mouse atherosclerotic lesions carried cholesterol, the finding supporting the biological significance of MD-2 cholesterol binding. These results help understand the molecular basis of TLR4 activation by OxCE and mechanisms of chronic inflammation in atherosclerosis. PMID:26806306

  4. Sequential memory: Binding dynamics

    NASA Astrophysics Data System (ADS)

    Afraimovich, Valentin; Gong, Xue; Rabinovich, Mikhail

    2015-10-01

    Temporal order memories are critical for everyday animal and human functioning. Experiments and our own experience show that the binding or association of various features of an event together and the maintaining of multimodality events in sequential order are the key components of any sequential memories—episodic, semantic, working, etc. We study a robustness of binding sequential dynamics based on our previously introduced model in the form of generalized Lotka-Volterra equations. In the phase space of the model, there exists a multi-dimensional binding heteroclinic network consisting of saddle equilibrium points and heteroclinic trajectories joining them. We prove here the robustness of the binding sequential dynamics, i.e., the feasibility phenomenon for coupled heteroclinic networks: for each collection of successive heteroclinic trajectories inside the unified networks, there is an open set of initial points such that the trajectory going through each of them follows the prescribed collection staying in a small neighborhood of it. We show also that the symbolic complexity function of the system restricted to this neighborhood is a polynomial of degree L - 1, where L is the number of modalities.

  5. Sequential memory: Binding dynamics.

    PubMed

    Afraimovich, Valentin; Gong, Xue; Rabinovich, Mikhail

    2015-10-01

    Temporal order memories are critical for everyday animal and human functioning. Experiments and our own experience show that the binding or association of various features of an event together and the maintaining of multimodality events in sequential order are the key components of any sequential memories-episodic, semantic, working, etc. We study a robustness of binding sequential dynamics based on our previously introduced model in the form of generalized Lotka-Volterra equations. In the phase space of the model, there exists a multi-dimensional binding heteroclinic network consisting of saddle equilibrium points and heteroclinic trajectories joining them. We prove here the robustness of the binding sequential dynamics, i.e., the feasibility phenomenon for coupled heteroclinic networks: for each collection of successive heteroclinic trajectories inside the unified networks, there is an open set of initial points such that the trajectory going through each of them follows the prescribed collection staying in a small neighborhood of it. We show also that the symbolic complexity function of the system restricted to this neighborhood is a polynomial of degree L - 1, where L is the number of modalities. PMID:26520084

  6. Radioprotective effect of the Barbados Cherry (Malpighia glabra L.) against radiopharmaceutical Iodine-131 in Wistar rats in vivo

    PubMed Central

    2014-01-01

    Background The increasing consumption of fruits and vegetables has contributed to the improvement of populational health, due in part, to the abundance of antioxidants in these foods. Antioxidants reduce the level of oxidative damage to DNA caused by free radicals and ionizing radiation, including the radioisotope iodine-131 (131I). This isotope is used for the diagnosis and treatment of thyroid injuries, such as hyperthyroidism and cancer. Methods This study aimed to evaluate the radioprotective and cytotoxic activity of acute and subchronic treatments with Barbados Cherry (BC) (Malpighia glabra L.) fruit juice (5 mg), which is rich in potent antioxidants such as vitamin C, phenols, carotenoids, anthocyanins and yellow flavonoids and its activity against the mutagenic activity of the therapeutic dose of 25 μCi of radioiodine for hyperthyroidism. The test system used was the bone marrow cells of Wistar rats (Rattus norvegicus) that were treated in vivo by gavage. Results BC showed radioprotective activity in acute treatments, which is most likely due to the joint action of its antioxidant components. In subchronic treatments, the continuous treatment presented an effective radioprotective activity, which was significantly different from treatment with the radiopharmaceutical only. Treatment with BC prior to (PRE) and simultaneous with (SIM) ionizing radiation decreased the number of induced chromosomal alterations, while post-treatment produced no protective effect. In addition, BC exhibited no cytotoxic activity. Conclusions These data serve as evidence that BC can be used as a preventive health measure to improve public health quality by countering the action of inevitable exposure to mutagens, such as 131I. PMID:24479389

  7. Evaluation of deoxyribonucleic acid toxicity induced by the radiopharmaceutical 99mTechnetium-Methylenediphosphonic acid and by stannous chloride in Wistar rats.

    PubMed

    Mattos, José Carlos Pelielo De; Matos, Vanessa Coutinho de; Rodrigues, Michelle Pinheiro; Oliveira, Marcia Betânia Nunes de; Dantas, Flavio José S; Santos-Filho, Sebastião David; Bernardo-Filho, Mario; Caldeira-de-Araujo, Adriano

    2012-01-01

    Radiopharmaceuticals are employed in patient diagnostics and disease treatments. Concerning the diagnosis aspect, technetium-99m (99mTc) is utilized to label radiopharmaceuticals for single photon computed emission tomography (SPECT) due to its physical and chemical characteristics. 99mTc fixation on pharmaceuticals depends on a reducing agent, stannous chloride (SnCl(2)) being the most widely-utilized. The genotoxic, clastogenic and anegenic properties of the 99mTc-MDP(methylene diphosphonate used for bone SPECT) and SnCl(2) were evaluated in Wistar rat blood cells using the Comet assay and micronucleus test. The experimental approach was to endovenously administer NaCl 0.9% (negative control), cyclophosphamide 50 mg/kg b.w. (positive control), SnCl(2) 500 μg/mL or 99mTc-MDP to animals and blood samples taken immediately before the injection, 3, and 24 h after (in the Comet assay) and 36 h after, for micronucleus test. The data showed that both SnCl(2) and 99mTc-MDP-induced deoxyribonucleic acid (DNA) strand breaks in rat total blood cells, suggesting genotoxic potential. The 99mTc-MDP was not able to induce a significant DNA strand breaks increase in in vivo assays. Taken together, the data presented here points to the formation of a complex between SnCl(2) in the radiopharmaceutical 99mTc-MDP, responsible for the decrease in cell damage, compared to both isolated chemical agents. These findings are important for the practice of nuclear medicine. PMID:23117436

  8. Library Binding Manual. Revised Edition.

    ERIC Educational Resources Information Center

    Lakhanpal, S. K.

    This procedural manual is designed to be used in bindery sections in public, university and special libraries. It briefly discusses these general matters: administrative control; selection of a binder; when and what to bind; conventional binding; routines; missing issues; schedule for shipments; temporary binding; rare books, maps and newspapers;…

  9. Alcohol binding to liposomes by 2H NMR and radiolabel binding assays: does partitioning describe binding?

    PubMed Central

    Dubey, A K; Eryomin, V A; Taraschi, T F; Janes, N

    1996-01-01

    Implicit within the concept of membrane-buffer partition coefficients of solutes is a nonspecific solvation mechanism of solute binding. However, (2)H NMR studies of the binding of (2)H(6)-ethanol and [1-(2)H(2)] n-hexanol to phosphatidylcholine vesicles have been interpreted as evidence for two distinct alcohol binding modes. One binding mode was reported to be at the membrane surface. The second mode was reported to be within the bilayer interior. An examination of the (2)H NMR binding studies, together with direct radiolabel binding assays, shows that other interpretations of the data are more plausible. The results are entirely consistent with partitioning (nonspecific binding) as the sole mode of alcohol binding to liposomes, in accord with our previous thermodynamic interpretation of alcohol action in phosphatidylcholine liposomes. PMID:9172754

  10. Carboplatin binding to histidine

    SciTech Connect

    Tanley, Simon W. M.; Diederichs, Kay; Kroon-Batenburg, Loes M. J.; Levy, Colin; Schreurs, Antoine M. M.; Helliwell, John R.

    2014-08-29

    An X-ray crystal structure showing the binding of purely carboplatin to histidine in a model protein has finally been obtained. This required extensive crystallization trials and various novel crystal structure analyses. Carboplatin is a second-generation platinum anticancer agent used for the treatment of a variety of cancers. Previous X-ray crystallographic studies of carboplatin binding to histidine (in hen egg-white lysozyme; HEWL) showed the partial conversion of carboplatin to cisplatin owing to the high NaCl concentration used in the crystallization conditions. HEWL co-crystallizations with carboplatin in NaBr conditions have now been carried out to confirm whether carboplatin converts to the bromine form and whether this takes place in a similar way to the partial conversion of carboplatin to cisplatin observed previously in NaCl conditions. Here, it is reported that a partial chemical transformation takes place but to a transplatin form. Thus, to attempt to resolve purely carboplatin binding at histidine, this study utilized co-crystallization of HEWL with carboplatin without NaCl to eliminate the partial chemical conversion of carboplatin. Tetragonal HEWL crystals co-crystallized with carboplatin were successfully obtained in four different conditions, each at a different pH value. The structural results obtained show carboplatin bound to either one or both of the N atoms of His15 of HEWL, and this particular variation was dependent on the concentration of anions in the crystallization mixture and the elapsed time, as well as the pH used. The structural details of the bound carboplatin molecule also differed between them. Overall, the most detailed crystal structure showed the majority of the carboplatin atoms bound to the platinum centre; however, the four-carbon ring structure of the cyclobutanedicarboxylate moiety (CBDC) remained elusive. The potential impact of the results for the administration of carboplatin as an anticancer agent are described.

  11. Comparison of the Absorbed Dose for 99mTc-Diethylenetriaminepentaacetic Acid and 99mTc-Ethylenedicysteine Radiopharmaceuticals using Medical Internal Radiation Dosimetry

    PubMed Central

    Pirdamooie, Shokufeh; Shanei, Ahmad; Moslehi, Masoud

    2015-01-01

    The aim of this study was the investigation of absorbed dose to the kidneys, spleen, and liver during technetium-99 m ethylene dicysteine and technetium-99 m diethylenetriaminepentaacetic acid (99mTc-EC and 99mTc-DTPA) kidney scan. Patients who had been prepared for the kidney scan, were divided into two groups (Groups 1 and 2). The first group (Group 1) and the second group (Group 2) received intravenous injection of 99mTc-EC and 99mTc-DTP, respectively. A certain amount of radiopharmaceuticals was injected into each patient and was immediately imaged with dual-head gamma camera to calculate the activity through the conjugated view method. Then, the doses of kidney, liver, and spleen were measured using medical internal radiation dosimetry method. Finally, absorbed dose of these organs was compared. Based on these different results (P < 0.05), organs absorbed dose was significantly less with radiopharmaceutical 99mTc-EC as compared with 99mTc-DTPA. PMID:26284173

  12. An experimental model to study the effects of a senna extract on the blood constituent labeling and biodistribution of a radiopharmaceutical in rats

    PubMed Central

    Souza, Deise Elizabeth; Pereira, Marcia Oliveira; Bernardo, Luciana Camargo; Carmo, Fernanda Santos; de Souza da Fonseca, Adenilson; Bernardo-Filho, Mario

    2011-01-01

    ABSTRACT Cassia angustifolia Vahl (senna) is a natural product that contains sennosides, which are active components that affect the intestinal tract and induce diarrhea. Authors have shown that senna produces DNA (deoxyribonucleic acid) lesions in Escherichia coli cultures and can act as an antifungal agent. Natural drugs can alter the labeling of blood constituents with technetium-99m (99mTc) and can affect the biodistribution of radiopharmaceuticals. In this work, we have evaluated the influence of a senna extract on the radiolabeling of blood constituents and on the biodistribution of the radiopharmaceutical sodium pertechnetate (Na99mTcO4) in Wistar rats. Twelve animals were treated with senna extract for 7 days. Blood samples were withdrawn from the animals and the radiolabeling procedure was carried out. The senna extract did not modify the radiolabeling of the blood constituents. A biodistributional assay was performed by administering Na99mTcO4 and determining its activity in different organs and in blood. The senna extract altered the biodistribution of Na99mTcO4 in the thyroid, liver, pancreas, lungs and blood. These results are associated with properties of the chemical substances present in the aqueous senna extract. Although these assays were performed in animals, our findings suggest that caution should be exercised when nuclear medicine examinations using Na99mTcO4 are conducted in patients who are using senna extract. PMID:21552677

  13. An overview of translational (radio)pharmaceutical research related to certain oncological and non-oncological applications

    PubMed Central

    Cona, Marlein Miranda; de Witte, Peter; Verbruggen, Alfons; Ni, Yicheng

    2013-01-01

    Translational medicine pursues the conversion of scientific discovery into human health improvement. It aims to establish strategies for diagnosis and treatment of diseases. Cancer treatment is difficult. Radio-pharmaceutical research has played an important role in multiple disciplines, particularly in translational oncology. Based on the natural phenomenon of necrosis avidity, OncoCiDia has emerged as a novel generic approach for treating solid malignancies. Under this systemic dual targeting strategy, a vascular disrupting agent first selectively causes massive tumor necrosis that is followed by iodine-131 labeled-hypericin (123I-Hyp), a necrosis-avid compound that kills the residual cancer cells by crossfire effect of beta radiation. In this review, by emphasizing the potential clinical applicability of OncoCiDia, we summarize our research activities including optimization of radioiodinated hypericin Hyp preparations and recent studies on the biodistribution, dosimetry, pharmacokinetic and, chemical and radiochemical toxicities of the preparations. Myocardial infarction is a global health problem. Although cardiac scintigraphy using radioactive perfusion tracers is used in the assessment of myocardial viability, searching for diagnostic imaging agents with authentic necrosis avidity is pursued. Therefore, a comparative study on the biological profiles of the necrosis avid 123I-Hyp and the commercially available 99mTc-Sestamibi was conducted and the results are demonstrated. Cholelithiasis or gallstone disease may cause gallbladder inflammation, infection and other severe complications. While studying the mechanisms underlying the necrosis avidity of Hyp and derivatives, their naturally occurring fluorophore property was exploited for targeting cholesterol as a main component of gallstones. The usefulness of Hyp as an optical imaging agent for cholelithiasis was studied and the results are presented. Multiple uses of automatic contrast injectors may reduce costs

  14. Correction Factors Applied to Finger Dosimetry: A Theoretical Assessment of Appropriate Values for Use in Handling Radiopharmaceuticals

    SciTech Connect

    Sherbini, Sami; Ilas, Dan; Eckerman, Keith F; DeCicco, Joseph

    2011-01-01

    United States Nuclear Regulatory Commission (USNRC) regulations limit the dose to the skin to 500 mSv per year. This is also the dose limit recommended by the International Commission on Radiological Protection (ICRP). The operational quantity recommended by ICRP for quantifying dose to the skin is the personal dose equivalent, Hp(0.07) and is identical to NRC s shallow dose equivalent, Hs, also measured at a skin depth of 7 mg cm 2. However, whereas ICRP recommends averaging the dose to the skin over an area of 1 cm2 regardless of the size of the exposed area of skin, USNRC requires the shallow dose equivalent to be averaged over 10 cm2. To monitor dose to the skin of the hands of workers handling radioactive materials and particularly in radiopharmaceutical manufacturing facilities, which is the focus of this work, workers are frequently required to wear finger ring dosimeters. The dosimeters monitor the dose at the location of the sensitive element, but this is not the dose required to show compliance (i.e., the dose averaged over the highest exposed contiguous 10 cm2 of skin). Therefore, it may be necessary to apply a correction factor that enables estimation of the required skin dose from the dosimeter reading. This work explored the effects of finger ring placement and of the geometry of the radioactive materials being handled by the worker on the relationship between the dosimeter reading and the desired average dose. A mathematical model of the hand was developed for this purpose that is capable of positioning the fingers in any desired grasping configuration, thereby realistically modeling manipulation of any object. The model was then used with the radiation transport code MCNP to calculate the dose distribution on the skin of the hand when handling a variety of radioactive vials and syringes, as well as the dose to the dosimeter element. Correction factors were calculated using the results of these calculations and examined for any patterns that may be

  15. Cold Spots in Protein Binding.

    PubMed

    Shirian, Jason; Sharabi, Oz; Shifman, Julia M

    2016-09-01

    Understanding the energetics and architecture of protein-binding interfaces is important for basic research and could potentially facilitate the design of novel binding domains for biotechnological applications. It is well accepted that a few key residues at binding interfaces (binding hot spots) are responsible for contributing most to the free energy of binding. In this opinion article, we introduce a new concept of 'binding cold spots', or interface positions occupied by suboptimal amino acids. Such positions exhibit a potential for affinity enhancement through various mutations. We give several examples of cold spots from different protein-engineering studies and argue that identification of such positions is crucial for studies of protein evolution and protein design. PMID:27477052

  16. DOE SBIR Phase I Grant No. DE-FG02-00ER83067, ''A Flexible and Economical Automated Nucleophilic [{sup 18}F]Fluorination synthesis System for PET Radiopharmaceuticals.'' Final Technical Report

    SciTech Connect

    Padgett, Henry C.

    2001-08-04

    Phase I Final Report. A prototype manual remote synthesis system based on the unit operations approach was designed, constructed, and functionally tested. This general-purpose system was validated by its configuration and initial use for the preparation of the PET radiopharmaceutical [F-18]FLT using [F-18]fluoride ion.

  17. Quarkonium binding and entropic force

    NASA Astrophysics Data System (ADS)

    Satz, Helmut

    2015-05-01

    A bound state represents a balance between repulsive kinetic and attractive potential energy. In a hot quark-gluon plasma, the interaction potential experiences medium effects. Color screening modifies the attractive binding force between the quarks, while the increase of entropy with separation gives rise to a growing repulsion. We study the role of these phenomena for in-medium binding and dissociation. It is found that the relevant potential for binding is the free energy ; with increasing separation, further binding through the internal energy is compensated by repulsive entropic effects.

  18. Rapid brain scanning radiopharmaceutical

    DOEpatents

    Sargent, T.W. III; Shulgin, A.T.; Mathis, C.A.

    1987-03-03

    A method for detecting the blood flow in animals, particularly in the brain, is provided wherein a detectable amount of a novel radioactive compound of the formula 1 is administered to one animal: as given in figure in patent wherein R[sub 1] and R[sub 2] are independently alkyl of 1 to 6 carbon atoms or benzyl; R[sub 3] is alkyl of 1 to 6 carbon atoms, benzyl, cyclopropylalkyl of 4 to 6 carbon atoms, or cyanoalkyl of 2 to 6 carbon atoms; R[sub 4] is hydrogen, benzyl or alkyl of 1 to 6 carbon atoms; with the provisos that R[sub 4] is not isopropyl and when R[sub 4] is methyl, R[sub 3] is not benzyl; and X is a radioactive halogen. 2 figs.

  19. Rapid brain scanning radiopharmaceutical

    DOEpatents

    Sargent, III, Thornton W.; Shulgin, Alexander T.; Mathis, Chester A.

    1987-01-01

    A method for detecting the blood flow in animals, particularly in the brain, is provided wherein a detectable amount of a novel radioactive compound of the formula I is administered to one animal: ##STR1## wherein R.sub.1 and R.sub.2 are independently alkyl of 1 to 6 carbon atoms or benzyl; R.sub.3 is alkyl of 1 to 6 carbon atoms, benzyl, cyclopropylalkyl of 4 to 6 carbon atoms, or cyanoalkyl of 2 to 6 carbon atoms; R.sub.4 is hydrogen, benzyl or alkyl of 1 to 6 carbon atoms; with the provisos that R.sub.4 is not isopropyl and when R.sub.4 is methyl, R.sub.3 is not benzyl; and X is a radioactive halogen.

  20. Stabalized radiopharmaceutical compositions

    SciTech Connect

    Charleson, F.P.

    1989-11-14

    This patent describes a stabilized radiopharmaceutial composition. It comprises: a molecule containing a radioactive iodine atom and a stabilize, selected from the group consisting of ascorbic acid, nicotinamide and its corresponding amides, or a mixture of ascorbic acid and nicotinamide and its amides, in a sufficient amount to stabilize against radiolytic decomposition.

  1. Identification of consensus binding sites clarifies FMRP binding determinants.

    PubMed

    Anderson, Bart R; Chopra, Pankaj; Suhl, Joshua A; Warren, Stephen T; Bassell, Gary J

    2016-08-19

    Fragile X mental retardation protein (FMRP) is a multifunctional RNA-binding protein with crucial roles in neuronal development and function. Efforts aimed at elucidating how FMRP target mRNAs are selected have produced divergent sets of target mRNA and putative FMRP-bound motifs, and a clear understanding of FMRP's binding determinants has been lacking. To clarify FMRP's binding to its target mRNAs, we produced a shared dataset of FMRP consensus binding sequences (FCBS), which were reproducibly identified in two published FMRP CLIP sequencing datasets. This comparative dataset revealed that of the various sequence and structural motifs that have been proposed to specify FMRP binding, the short sequence motifs TGGA and GAC were corroborated, and a novel TAY motif was identified. In addition, the distribution of the FCBS set demonstrates that FMRP preferentially binds to the coding region of its targets but also revealed binding along 3' UTRs in a subset of target mRNAs. Beyond probing these putative motifs, the FCBS dataset of reproducibly identified FMRP binding sites is a valuable tool for investigating FMRP targets and function. PMID:27378784

  2. Reversible calcitonin binding to solubilized sheep brain binding sites.

    PubMed Central

    Sexton, P M; Schneider, H G; D'Santos, C S; Mendelsohn, F A; Kemp, B E; Moseley, J M; Martin, T J; Findlay, D M

    1991-01-01

    In this study we have solubilized and characterized binding sites for calcitonin (CT) from sheep brainstem. Autoradiography of 125I-labelled salmon CT (125I-sCT) binding to sheep diencephalon revealed a similar pattern of binding to that seen in other species, although the extent of distribution was greater in the sheep. CT binding activity could be extracted from membranes with either CHAPS or digitonin, but not with beta-octyl glucoside, 125I-sCT binding was saturable, with a dissociation constant for CHAPS-solubilized membranes of 2.8 +/- 0.5 nM and a maximum binding site concentration of 6.2 +/- 1.6 pmol/mg of protein. In competition binding studies, various CTs and their analogues demonstrated a similar rank order of potency to that seen in other CT receptor systems, Optimal binding occurred in the pH range 6.5-7.5, and was decreased in the presence of NaCl concentrations greater than 200 mM. In contrast with most other CT receptor binding systems, in which binding is poorly reversible, the binding of 125I-sCT to sheep brain binding sites underwent substantial dissociation upon addition of excess unlabelled sCT, with 40% and 46% dissociation after 2 h at 4 degree C in particulate and solubilized membranes respectively. Photoaffinity labelling of the binding site with the biologically active analogue 125I-[Arg11,18,4-azidobenzoyl-Lys14]sCT and analysis on SDS/PAGE under reducing conditions revealed a specific protein band of Mr approximately solubilized and particulate brain membranes. This is in accordance with the molecular size of CT receptors in other tissues where two species of receptor have been identified. one of Mr approximately 71,000 and another of Mr approximately 88,000. These results demonstrate the presence of high concentrations of CT binding sites in sheep brain which display different kinetic properties to those of CT receptors found in other tissues. Images Fig. 1. Fig. 6. PMID:1846527

  3. Evaluation of absorbed and effective doses to patients from radiopharmaceuticals using the ICRP 110 reference computational phantoms and ICRP 103 formulation.

    PubMed

    Hadid, Lama; Gardumi, Anna; Desbrée, Aurélie

    2013-09-01

    In diagnostic nuclear medicine, mean absorbed doses to patients' organs and effective doses are published for standard stylised anatomic models. To provide more realistic and detailed geometries of the human morphology, the International Commission on Radiological Protection (ICRP) has recently adopted male and female voxel phantoms to represent the reference adult. This work investigates the impact of the use of these new computational phantoms. The absorbed doses were calculated for 11 different radiopharmaceuticals currently used in diagnostic nuclear medicine. They were calculated for the ICRP 110 reference computational phantoms using the OEDIPE software and the MCNP extended Monte Carlo code. The biokinetic models were issued from ICRP Publications 53, 80 and 106. The results were then compared with published values given in these ICRP Publications. To discriminate the effect of anatomical differences on organ doses from the effect of the calculation method, the Monte Carlo calculations were repeated for the reference adult stylised phantom. The voxel effect, the influence of the use of different densities and nuclear decay data were also investigated. Effective doses were determined for the ICRP 110 adult reference computational phantom with the tissue weighting factor of ICRP Publication 60 and the tissue weighting factors of ICRP Publication 103. The calculation method and, in particular, the simulation of the electron transport have a significant influence on the calculated doses, especially, for small and walled organs. Overestimates of >200 % were observed for the urinary bladder wall of the stylised phantom compared with the computational phantoms. The unrealistic organ topology of the stylised phantom leads to important dose differences, sometimes by an order of magnitude. The effective doses calculated using the new computational phantoms and the new tissue weighting factors are globally lower than the published ones, except for some

  4. Development of more efficacious Tc-99m organ imaging agents for use in nuclear medicine by analytical characterization of radiopharmaceutical mixtures. Progress report, May 1, 1980-April 30, 1981. [/sup 99m/Tc(NaBH/sub 4/)HEDP

    SciTech Connect

    Heineman, W. R.; Deutsch, E. A.

    1980-12-01

    High performance liquid chromatography (HPLC) was used to efficiently separate and detect the individual components in a radiopharmaceutical mixture. A procedure for separating Tc(NaBH/sub 4/)HEDP radiopharmaceutical analogues by anion exchange HPLC with uv-visible and ..gamma.. detection was developed. Such preparations consist of as many as 7 Tc-containing components, the relative quantities of which are highly dependent on the conditions during preparation and subsequent handling. The in vivo distributions of 3 of the isolated Tc-HEDP species were evaluated as skeletal imaging agents in normal rats. The chromatographically separated Tc-HEDP components exhibit distinctly different biodistributions which are related to the chromatographic characteristics of the individual components. These same Tc-HEDP components were evaluated for uptake in myocardial infarcts using the isoproterenol-induced necrosis model in the rat. The relative uptake of the various components in the infarcted heart parallels the skeletal uptake. An optically transparent thin layer electrochemical flow cell was developed and characterized. This cell enables optical and electrochemical measurements to be made simultaneously on individual Tc-HEDP complexes as they elute from the HPLC. These results demonstrate the potential presence of numerous technetium complexes in radiopharmaceuticals and the efficacy of HPLC as a mode of separation and detection of these complexes. One particular component in the Tc(NaBH/sub 4/)HEDP radiopharmaceutical analogue is more effective than the others for both skeletal and myocardial infarct uptake. This is strongly suggestive that a more efficacious radiopharmaceutical would result from the administration of this single component.

  5. Binding Energy and Enzymatic Catalysis.

    ERIC Educational Resources Information Center

    Hansen, David E.; Raines, Ronald T.

    1990-01-01

    Discussed is the fundamental role that the favorable free energy of binding of the rate-determining transition state plays in catalysis. The principle that all of the catalytic factors discussed are realized by the use of this binding energy is reviewed. (CW)

  6. Cholinergic influences on feature binding.

    PubMed

    Botly, Leigh C P; De Rosa, Eve

    2007-04-01

    The binding problem refers to the fundamental challenge of the central nervous system to integrate sensory information registered by multiple brain regions to form a unified neural representation of a stimulus. Human behavioral, neuropsychological, and functional neuroimaging evidence suggests a fundamental role for attention in feature binding; however, its neurochemical basis is currently unknown. This study examined whether acetylcholine (ACh), a neuromodulator that has been implicated in attentional processes, plays a critical role in feature binding. Using a within-subjects pharmacological design and the cholinergic muscarinic antagonist scopolamine, the present experiments demonstrate, in a rat model, a critical role for the cortical muscarinic cholinergic system in feature binding. Specifically, ACh and the attentional resources that it supports are essential for the initial feature binding process but are not required to maintain neural representations of bound stimuli. PMID:17469916

  7. A strategy for the study of cerebral amino acid transport using iodine-123-labeled amino acid radiopharmaceutical: 3-iodo-alpha-methyl-L-tyrosine

    SciTech Connect

    Kawai, K.; Fujibayashi, Y.; Saji, H.; Yonekura, Y.; Konishi, J.; Kubodera, A.; Yokoyama, A. )

    1991-05-01

    We examined the brain accumulation of iodine-123-iodo-alpha-methyl-L-tyrosine ({sup 123}I-L-AMT) in mice and rats. I-L-AMT showed high brain accumulation in mice, and in rats; rat brain uptake index exceeded that of {sup 14}C-L-tyrosine. The brain uptake index and the brain slice studies indicated the affinity of I-L-AMT for carrier-mediated and stereoselective active transport systems, respectively; both operating across the blood-brain barrier and cell membranes of the brain. The tissue homogenate analysis revealed that most of the accumulated radioactivity belonged to intact I-L-AMT, an indication of its stability. Thus, {sup 123}I-L-AMT appears to be a useful radiopharmaceutical for the selective measurement of cerebral amino acid transport.

  8. A Method to Predict Response of Cell Populations to Cocktails of Chemotherapeutics and Radiopharmaceuticals: Validation with Daunomycin, Doxorubicin, and the Alpha Particle Emitter 210Po

    PubMed Central

    Akudugu, John M.; Howell, Roger W.

    2012-01-01

    There is considerable interest in the use of α-emitting radionuclides in radioimmunotherapy. However, the high toxicity of α-emitting radionuclides often does not permit administration of high activities for fear of normal tissue toxicity. Accordingly, targeting procedures need to be optimized for improved tumor control and minimized normal tissue toxicity. To guide design of effective cocktails of α-emitting radiopharmaceuticals and chemotherapy drugs, approaches that can predict biological response of a cell population on a cell-by-cell basis are needed. Methods Cells were concomitantly treated with the α-particle emitting radiochemical 210Po-citrate and daunomycin, or with 210Po-citrate and doxorubicin. The responses of the treated cell populations were measured with a colony forming assay. The nonuniform cellular incorporation of the radiochemical and drugs was determined simultaneously on a cell-by-cell basis using flow cytometry. Monte Carlo methods were used to simulate cell survival on the of basis individual cell incorporation of each cytotoxic agent and validated by direct comparison with the experimental clonogenic cell survival. Results Both daunomycin and doxorubicin enhanced the toxicity of the α-particles with a magnitude greater than expected based on single-agent toxicities. Cell survival obtained by Monte Carlo simulation was in good agreement with clonogenic cell survival for the combination treatments. Conclusion Flow cytometry assisted Monte Carlo simulations can be used to predict toxicity of cocktails of α-emitting radiopharmaceuticals and chemotherapy drugs in a manner that takes into account the effects of nonuniform distributions of agents within cell populations. PMID:22503536

  9. Development of a rhenium-186-labeled MAG3-conjugated bisphosphonate for the palliation of metastatic bone pain based on the concept of bifunctional radiopharmaceuticals.

    PubMed

    Ogawa, Kazuma; Mukai, Takahiro; Arano, Yasushi; Ono, Masahiro; Hanaoka, Hirofumi; Ishino, Seigo; Hashimoto, Kazuyuki; Nishimura, Hiroshi; Saji, Hideo

    2005-01-01

    Rhenium-186-1-hydroxyethylidene-1,1-diphosphonate (186Re-HEDP) has been used for the palliation of metastatic bone pain. Delayed blood clearance and high gastric uptake of radioactivity have been observed upon injection, due to the instability of (186)Re-HEDP in vivo. In this study, on the basis of the concept of bifunctional radiopharmaceuticals, we designed a stable 186Re-mercaptoacetylglycylglycylglycine (MAG3) complex-conjugated bisphosphonate, [[[[(4-hydroxy-4,4-diphosphonobutyl)carbamoylmethyl]carbamoylmethyl]carbamoylmethyl]carbamoylmethanethiolate]oxorhenium(V) (186Re-MAG3-HBP). As a precursor, [1-hydroxy-1-phosphono-4-[2-[2-[2-(2-tritylmercaptoacetylamino)acetylamino]acetylamino]acetylamino]butyl]phosphonic acid (Tr-MAG3-HBP) was synthesized by the conjugation of N-[(tritylmercapto)acetyl]glycylglycylglycine (Tr-MAG3) with the bisphosphonate analogue. After deprotection of the trityl group of Tr-MAG3-HBP, 186Re-labeling was performed by reacting 186ReO4- with SnCl2 in citrate buffer. After purification by HPLC, 186Re-MAG3-HBP showed a radiochemical purity of over 95%. To compare the stability of 186Re-MAG3-HBP and 186Re-HEDP, these (186)Re complexes were incubated in phosphate buffer. No measurable decomposition of 186Re-MAG3-HBP occurred over a 24-h period, while only approximately 30% of 186Re-HEDP remained intact 24 h postincubation. In biodistribution experiments, the radioactivity level of 186Re-MAG3-HBP in bone was significantly higher than that of (186)Re-HEDP. Blood clearance of 186Re-MAG3-HBP was faster than that of 186Re-HEDP. In addition, the gastric accumulation of 186Re-MAG3-HBP radioactivity was lower than that of 186Re-HEDP. In conclusion, 186Re-MAG3-HBP is expected to be a useful radiopharmaceutical for the palliation of metastatic bone pain. PMID:16029015

  10. Cooperative binding: a multiple personality.

    PubMed

    Martini, Johannes W R; Diambra, Luis; Habeck, Michael

    2016-06-01

    Cooperative binding has been described in many publications and has been related to or defined by several different properties of the binding behavior of the ligand to the target molecule. In addition to the commonly used Hill coefficient, other characteristics such as a sigmoidal shape of the overall titration curve in a linear plot, a change of ligand affinity of the other binding sites when a site of the target molecule becomes occupied, or complex roots of the binding polynomial have been used to define or to quantify cooperative binding. In this work, we analyze how the different properties are related in the most general model for binding curves based on the grand canonical partition function and present several examples which highlight differences between the cooperativity characterizing properties which are discussed. Our results mainly show that among the presented definitions there are not two which fully coincide. Moreover, this work poses the question whether it can make sense to distinguish between positive and negative cooperativity based on the macroscopic binding isotherm only. This article shall emphasize that scientists who investigate cooperative effects in biological systems could help avoiding misunderstandings by stating clearly which kind of cooperativity they discuss. PMID:26319983

  11. (/sup 3/)tetrahydrotrazodone binding. Association with serotonin binding sites

    SciTech Connect

    Kendall, D.A.; Taylor, D.P.; Enna, S.J.

    1983-05-01

    High (17 nM) and low (603 nM) affinity binding sites for (/sup 3/)tetrahydrotrazodone ((/sup 3/) THT), a biologically active analogue of trazodone, have been identified in rat brain membranes. The substrate specificity, concentration, and subcellular and regional distributions of these sites suggest that they may represent a component of the serotonin transmitter system. Pharmacological analysis of (/sup 3/)THT binding, coupled with brain lesion and drug treatment experiments, revealed that, unlike other antidepressants, (/sup 3/) THT does not attach to either a biogenic amine transporter or serotonin binding sites. Rather, it would appear that (/sup 3/)THT may be an antagonist ligand for the serotonin binding site. This probe may prove of value in defining the mechanism of action of trazodone and in further characterizing serotonin receptors.

  12. Benzodiazepine binding to bovine retina.

    PubMed

    Osborne, N N

    1980-02-01

    [3H]Diazepam binds to membrane preparations of the retina, suggesting that benzodiazepine receptors exist in this tissue. The binding characteristics are similar to those known to occur in the brain, with affinity constants in the same range. Unlike the finding in the brain, [3H]diazepam binding in the retina is not stimulated by GABA and other GABA agonists. These findings indicate that benzodiazepine receptors may have a more general function and not only be associated with anxiety or emotional behaviour. PMID:6302572

  13. Mercury binding on activated carbon

    SciTech Connect

    Bihter Padak; Michael Brunetti; Amanda Lewis; Jennifer Wilcox

    2006-11-15

    Density functional theory has been employed for the modeling of activated carbon (AC) using a fused-benzene ring cluster approach. Oxygen functional groups have been investigated for their promotion of effective elemental mercury binding on AC surface sites. Lactone and carbonyl functional groups yield the highest mercury binding energies. Further, the addition of halogen atoms has been considered to the modeled surface, and has been found to increase the AC's mercury adsorption capacity. The mercury binding energies increase with the addition of the following halogen atoms, F {gt} Cl {gt} Br {gt} I, with the fluorine addition being the most promising halogen for increasing mercury adsorption.

  14. Coordination chemistry of the {sup 212}Pb/{sup 212}Bi nuclear transformation: Alpha-emitting radiopharmaceuticals. Final technical report

    SciTech Connect

    Parks, N.J.; Harris, W.R.; Keen, C.L.; Cooper, S.R.

    1992-07-01

    Subdivisions of this project are: (a) the synthesis of prototypical thiolate and dithiocarbamate based hexacoordinate complexes, (b) radiochemical engineering for generation of no-carrier-added lead and bismuth radioelements, (c) the first isolation of bismuth-binding proteins from in vivo studies with cyclotron produced {sup 205/206}Bi tracer, and (d) initial development of transport mechanisms for the intracellular radiobiological study of alpha emitting bismuth, and (e) the initiation of chemical equilibrium studies and biochemical pathways with cyclotron-produced, no-carrier-added, {sup 203}Pb (T{sub 1/2} = 51 hr).

  15. Superresolution microscopy with transient binding.

    PubMed

    Molle, Julia; Raab, Mario; Holzmeister, Susanne; Schmitt-Monreal, Daniel; Grohmann, Dina; He, Zhike; Tinnefeld, Philip

    2016-06-01

    For single-molecule localization based superresolution, the concentration of fluorescent labels has to be thinned out. This is commonly achieved by photophysically or photochemically deactivating subsets of molecules. Alternatively, apparent switching of molecules can be achieved by transient binding of fluorescent labels. Here, a diffusing dye yields bright fluorescent spots when binding to the structure of interest. As the binding interaction is weak, the labeling is reversible and the dye ligand construct diffuses back into solution. This approach of achieving superresolution by transient binding (STB) is reviewed in this manuscript. Different realizations of STB are discussed and compared to other localization-based superresolution modalities. We propose the development of labeling strategies that will make STB a highly versatile tool for superresolution microscopy at highest resolution. PMID:26773299

  16. When is protein binding important?

    PubMed

    Heuberger, Jules; Schmidt, Stephan; Derendorf, Hartmut

    2013-09-01

    The present paper is an ode to a classic citation by Benet and Hoener (2002. Clin Pharm Ther 71(3):115-121). The now classic paper had a huge impact on drug development and the way the issue of protein binding is perceived and interpreted. Although the authors very clearly pointed out the limitations and underlying assumptions for their delineations, these are too often overlooked and the classic paper's message is misinterpreted by broadening to cases that were not intended. Some members of the scientific community concluded from the paper that protein binding is not important. This was clearly not intended by the authors, as they finished their paper with a paragraph entitled: "When is protein binding important?" Misinterpretation of the underlying assumptions in the classic work can result in major pitfalls in drug development. Therefore, we revisit the topic of protein binding with the intention of clarifying when clinically relevant changes should be considered during drug development. PMID:23650013

  17. SPECT Imaging of Mice with 99mTc-Radiopharmaceuticals Obtained from 99Mo Produced by 100Mo(n,2n)99Mo and Fission of 235U

    NASA Astrophysics Data System (ADS)

    Hashimoto, Kazuyuki; Nagai, Yasuki; Kawabata, Masako; Sato, Nozomi; Hatsukawa, Yuichi; Saeki, Hideya; Motoishi, Shoji; Ohta, Masayuki; Konno, Chikara; Ochiai, Kentaro; Kawauchi, Yukimasa; Ohta, Akio; Shiina, Takayuki; Takeuchi, Nobuhiro; Ashino, Hiroki; Nakahara, Yuto

    2015-04-01

    The distribution of 99mTc-radiopharmaceutical in mouse was determined by single photon emission computed tomography (SPECT) for the first time using 99mTc, which was separated by thermochromatography from 99Mo produced via the 100Mo(n,2n)99Mo reaction with accelerator neutrons. The SPECT image was comparable to that obtained using the fission product 99Mo. Radionuclidic and radiochemical purities of the separated 99mTc and its aluminum concentration met the United States Pharmacopeia regulatory requirements for 99mTc from the fission product 99Mo. These results provide important evidence that the 99mTc-radiopharmaceutical formulated using the (n,2n) 99Mo can be a promising substitute for the fission product 99Mo. The current and forthcoming problem of ensuring a reliable and constant supply of 99Mo in Japan can be partially mitigated.

  18. A Monte Carlo approach to small-scale dosimetry of solid tumour microvasculature for nuclear medicine therapies with (223)Ra-, (131)I-, (177)Lu- and (111)In-labelled radiopharmaceuticals.

    PubMed

    Amato, Ernesto; Leotta, Salvatore; Italiano, Antonio; Baldari, Sergio

    2015-07-01

    The small-scale dosimetry of radionuclides in solid-tumours is directly related to the intra-tumoral distribution of the administered radiopharmaceutical, which is affected by its egress from the vasculature and dispersion within the tumour. The aim of the present study was to evaluate the combined dosimetric effects of radiopharmaceutical distribution and range of the emitted radiation in a model of tumour microvasculature. We developed a computational model of solid-tumour microenvironment around a blood capillary vessel, and we simulated the transport of radiation emitted by (223)Ra, (111)In, (131)I and (177)Lu using the GEANT4 Monte Carlo. For each nuclide, several models of radiopharmaceutical dispersion throughout the capillary vessel were considered. Radial dose profiles around the capillary vessel, the Initial Radioactivity (IR) necessary to deposit 100 Gy of dose at the edge of the viable tumour-cell region, the Endothelial Cell Mean Dose (ECMD) and the Tumour Edge Mean Dose (TEMD), i.e. the mean dose imparted at the 250-μm layer of tissue, were computed. The results for beta and Auger emitters demonstrate that the photon dose is about three to four orders of magnitude lower than that deposited by electrons. For (223)Ra, the beta emissions of its progeny deliver a dose about three orders of magnitude lower than that delivered by the alpha emissions. Such results may help to characterize the dose inhomogeneities in solid tumour therapies with radiopharmaceuticals, taking into account the interplay between drug distribution from vasculature and range of ionizing radiations. PMID:25979209

  19. Development of more efficacious {Tc}-99m organ imaging agents for use in nuclear medicine by analytical characterization of radiopharmaceuticals. Annual technical progress report, September 1, 1992--August 31, 1993

    SciTech Connect

    Heineman, W.R.

    1993-05-03

    This research program is detailed at development of more efficacious technetium-99m radiopharmaceuticals for use as imaging agents in diagnostic nuclear medicine. We seek to isolate and develop distinct site imaging agents to provide diagnostic information concerning a given pathological condition. Analytical techniques are being developed to enable complete analysis of radiopharmaceutical preparations so that individual complexes can be characterized with respect to imaging efficacy and to enable a radiopharmaceutical to be monitored after injection into a test animal to determine the species that actually accumulates in an organ to provide the image. Administration of the isolated, single most effective imaging complex, rather than a mixture of technetium-containing complexes, wi-11 minimize radiation exposure to the patient and maximize diagnostic information available to the clinician. This report specifically describes the development of capillary electrophoresis (CE) for characterizating diphosphonate skeletal imaging agents. Advances in the development of electrochemical and fiber optic sensors for Tc and Re imaging agents are described. These sensors will ultimately be capable of monitoring a specific chemical state of an imaging agent in vivo after injection into a test animal by implantation in the organ of interest.

  20. Cholesterol binding to ion channels

    PubMed Central

    Levitan, Irena; Singh, Dev K.; Rosenhouse-Dantsker, Avia

    2014-01-01

    Numerous studies demonstrated that membrane cholesterol is a major regulator of ion channel function. The goal of this review is to discuss significant advances that have been recently achieved in elucidating the mechanisms responsible for cholesterol regulation of ion channels. The first major insight that comes from growing number of studies that based on the sterol specificity of cholesterol effects, show that several types of ion channels (nAChR, Kir, BK, TRPV) are regulated by specific sterol-protein interactions. This conclusion is supported by demonstrating direct saturable binding of cholesterol to a bacterial Kir channel. The second major advance in the field is the identification of putative cholesterol binding sites in several types of ion channels. These include sites at locations associated with the well-known cholesterol binding motif CRAC and its reversed form CARC in nAChR, BK, and TRPV, as well as novel cholesterol binding regions in Kir channels. Notably, in the majority of these channels, cholesterol is suggested to interact mainly with hydrophobic residues in non-annular regions of the channels being embedded in between transmembrane protein helices. We also discuss how identification of putative cholesterol binding sites is an essential step to understand the mechanistic basis of cholesterol-induced channel regulation. Clearly, however, these are only the first few steps in obtaining a general understanding of cholesterol-ion channels interactions and their roles in cellular and organ functions. PMID:24616704

  1. H2CHXdedpa and H4CHXoctapa-chiral acyclic chelating ligands for (67/68)Ga and (111)In radiopharmaceuticals.

    PubMed

    Ramogida, Caterina F; Cawthray, Jacqueline F; Boros, Eszter; Ferreira, Cara L; Patrick, Brian O; Adam, Michael J; Orvig, Chris

    2015-02-16

    The chiral acyclic ligands H2CHXdedpa (N4O2), H2CHXdedpa-bb (N4O2), and H4CHXoctapa (N4O4) (CHX = cyclohexyl/cyclohexane, H2dedpa = 1,2-[[6-carboxy-pyridin-2-yl]-methylamino]ethane, bb = N,N'-dibenzylated, H4octapa = N,N'-bis(6-carboxy-2-pyridylmethyl)-ethylenediamine-N,N'-diacetic acid) were synthesized, complexed with Ga(III) and/or In(III), and evaluated for their potential as chelating agents in radiopharmaceutical applications. The ligands were compared to the previously studied hexadentate H2dedpa and octadentate H4octapa ligands to determine the effect adding a chiral 1R,2R-trans-cyclohexane to replace the ethylenediamine backbone would have on metal complex stability and radiolabeling kinetics. It was found that [Ga(CHXdedpa)](+) showed very similar properties to those of [Ga(dedpa)](+), with only one isomer in solution observed by NMR spectroscopy, and minimal structural changes in the solid-state X-ray structure. Like [Ga(dedpa)](+), [Ga(CHXdedpa)](+) exhibited exceptionally high thermodynamic stability constants (log KML = 28.11(8)), and the chelate retained the ability to label (67)Ga quantitatively in 10 min at room temperature at ligand concentrations of 1 × 10(-5) M. In vitro kinetic inertness assays demonstrated the [(67)Ga(CHXdedpa)](+) complex to be more stable than [(67)Ga(dedpa)](+) in a human serum competition, with 90.5% and 77.8% of (67)Ga remaining chelate-bound after 2 h, respectively. Preliminary coordination studies of H4CHXoctapa with In(III) demonstrated [In(CHXoctapa)](-) to have an equivalently high thermodynamically stable constant as [In(octapa)](-), with log KML values of 27.16(9) and 26.76(14), respectively. The [(111)In(CHXoctapa)](-) complex showed exceptionally high in vitro kinetic inertness over 120 h in human serum, comparing well with previously reported [(111)In(octapa)](-) values, and an improved stability compared to the current industry "gold standards" 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA

  2. Development of additive [11C]CO2 target system in the KOTRON-13 cyclotron and its application for [11C]radiopharmaceutical production

    NASA Astrophysics Data System (ADS)

    Moon, Byung Seok; Lee, Hong Jin; Lee, Won Kyung; Hur, Min Goo; Yang, Seung Dae; Lee, Byung Chul; Kim, Sang Eun

    2015-08-01

    The KOTRON-13 cyclotron, which was developed in South Korea for the production of medical radioisotopes, has the structural limitation of only one beam-output port, restricting the production of the carbon-11 isotope. In the present study, we investigate the design of a switchable target system and develop an effective carbon-11 target in the KOTRON-13 cyclotron, for combination with the fluorine-18 target. The target system was designed by introducing a sliding-type element between the fluorine-18 and carbon-11 targets, a tailor-made C-11 target and its cooling system. For the efficient production of [11C]CO2, the desirable target shape and internal volume were determined by a Stopping and Range of Ions in Matter (SRIM) simulation program, and the target grid was modified to resist the cavity pressure during beam irradiation. We evaluated the [11C]CO2 production while varying the material and thickness of the target foil, oxygen content of the nitrogen gas, and target loading pressure. Using sliding-type equipment including an additional gate valve and a high vacuum in a beam line, the bi-directional conversion between the fluorine-18 and carbon-11 targets was efficient regarding the accurate beam irradiation on both targets. The optimal [11C]CO2 production for 30 min irradiation at 60 μA (86.6 ± 1.7 GBq in the target at EOB) was observed at a thickness of 19 μm with HAVAR® material as a target foil and a target loading pressure of 24 bar with nitrogen plus 300 ppb of oxygen gas. Additionally, the coolant cavity system in the target grid and target chamber is useful to remove the heat transferred to the target body by the internal convection of water and thereby ensure the stability of the [11C]CO2 production under a high beam current. In the application of C-11 labeled radiopharmaceuticals such as [11C]PIB, [11C]DASB, [11C]PBR28, [11C]Methionine and [11C]Clozapine, the radiochemical yields were shown to be 25-38% (decay corrected) with over 166 GBq/μmol of

  3. Water binding in legume seeds

    NASA Technical Reports Server (NTRS)

    Vertucci, C. W.; Leopold, A. C.

    1987-01-01

    The physical status of water in seeds has a pivotal role in determining the physiological reactions that can take place in the dry state. Using water sorption isotherms from cotyledon and axis tissue of five leguminous seeds, the strength of water binding and the numbers of binding sites have been estimated using van't Hoff analyses and the D'Arcy/Watt equation. These parameters of water sorption are calculated for each of the three regions of water binding and for a range of temperatures. Water sorption characteristics are reflective of the chemical composition of the biological materials as well as the temperature at which hydration takes place. Changes in the sorption characteristics with temperature and hydration level may suggest hydration-induced structural changes in cellular components.

  4. Computational Prediction of RNA-Binding Proteins and Binding Sites

    PubMed Central

    Si, Jingna; Cui, Jing; Cheng, Jin; Wu, Rongling

    2015-01-01

    Proteins and RNA interaction have vital roles in many cellular processes such as protein synthesis, sequence encoding, RNA transfer, and gene regulation at the transcriptional and post-transcriptional levels. Approximately 6%–8% of all proteins are RNA-binding proteins (RBPs). Distinguishing these RBPs or their binding residues is a major aim of structural biology. Previously, a number of experimental methods were developed for the determination of protein–RNA interactions. However, these experimental methods are expensive, time-consuming, and labor-intensive. Alternatively, researchers have developed many computational approaches to predict RBPs and protein–RNA binding sites, by combining various machine learning methods and abundant sequence and/or structural features. There are three kinds of computational approaches, which are prediction from protein sequence, prediction from protein structure, and protein-RNA docking. In this paper, we review all existing studies of predictions of RNA-binding sites and RBPs and complexes, including data sets used in different approaches, sequence and structural features used in several predictors, prediction method classifications, performance comparisons, evaluation methods, and future directions. PMID:26540053

  5. Unusual monoclonal DNA binding immunoglobulin.

    PubMed

    Sawada, S; Iijima, S; Kuwana, K; Nishinarita, S; Takeuchi, J; Shida, M; Karasaki, M; Amaki, I

    1983-03-01

    The monoclonal antibodies directed against DNA were produced by somatic cell hybridization with parental cells (SP-2) and spleen cells from nonimmunized autoimmune MRL/lpr mice. The immunoglobulins were recovered from the culture supernatant from hybridoma by a solid immunoadsorbent and antibody immunoprecipitation. The results from the specificities of DNA binding monoclonal immunoglobulins suggest that the antibodies to DNA have the antibody combining sites for both epitope of double stranded helix and base of DNA and support the concept of the multiple antigen binding potentials of the hybridoma autoantibodies. PMID:6857646

  6. RNA Bind-n-Seq: Measuring the Binding Affinity Landscape of RNA-Binding Proteins.

    PubMed

    Lambert, Nicole J; Robertson, Alex D; Burge, Christopher B

    2015-01-01

    RNA-binding proteins (RBPs) coordinate post-transcriptional control of gene expression, often through sequence-specific recognition of primary transcripts or mature messenger RNAs. Hundreds of RBPs are encoded in the human genome, most with undefined or incompletely defined biological roles. Understanding the function of these factors will require the identification of each RBP's distinct RNA binding specificity. RNA Bind-n-Seq (RBNS) is a high-throughput, cost-effective in vitro method capable of resolving sequence and secondary structure preferences of RBPs. Dissociation constants can also be inferred from RBNS data when provided with additional experimental information. Here, we describe the experimental procedures to perform RBNS and discuss important parameters of the method and ways that the experiment can be tailored to the specific RBP under study. Additionally, we present the conceptual framework and execution of the freely available RBNS computational pipeline and describe the outputs of the pipeline. Different approaches to quantify binding specificity, quality control metrics, and estimation of binding constants are also covered. PMID:26068750

  7. Development of more efficacious Tc-99m organ imaging agents for use in nuclear medicine by analytical characterization of radiopharmaceutical mixtures. Progress report, May 1, 1981-April 30, 1982

    SciTech Connect

    Heineman, W.R.; Deutsch, E.A.

    1981-12-01

    The objectives of this year's research were to develop a method for rapidly determining TcO/sub 4//sup -/ in /sup 99/Mo//sup 99m/Tc generator eluates, to improve the ability to chromatographically determine individual Tc-HEDP complexes in radiopharmaceuticals, and to investigate the effects of TcO/sub 4//sup -/ concentration and electrochemical reduction on the types and relative amounts of Tc-HEDP complexes present in a radiopharmaceutical formulation. A rapid and sensitive high performance liquid chromatographic (HPLC) method for the quantitative determination of pertechnetate (TcO/sub 4//sup -/) was developed. This HPLC-based analysis may be of considerable utility in assessing the history and function of /sup 99/MO/sup 99m/Tc generators as well as in the routine analysis of reduced technetium radiopharmaceuticals for the presence of undesired TcO/sub 4//sup -/. Encouraging results were obtained on a dimethyl amine column using aqueous (NH/sub 4/)/sub 2/SO/sub 4/ as the mobile phase. The preparation of Tc(NaBH/sub 4/) HEDP radiopharmaceutical analogues using varying concentrations of total TcO/sub 4//sup -/ shows a dramatic effect in the number and distribution of Tc-HEDP complexes over a TcO/sub 4//sup -/ concentration range of 10/sup -2/ to 10/sup -8/M. These results suggest that total TcO/sub 4//sup -/ concentration is an important parameter to be considered in the preparation of a specific Tc-HEDP complex to improve skeletal imaging. The preparation of Tc(electrode) HEDP radiopharmaceutical analogues by using electrochemical reduction was explored. The resulting solutions contain Tc-HEDP complexes that are tentatively identified as being the same complexes formed by NaBH/sub 4/ reduction, although the relative concentrations of these complexes are quite different with the two modes of reduction. Thus, electrochemical reduction shows promise as a viable route to the preparation of specific Tc-HEDP complexes for improved skeletal imaging.

  8. Synthetic heparin-binding growth factor analogs

    DOEpatents

    Pena, Louis A.; Zamora, Paul; Lin, Xinhua; Glass, John D.

    2007-01-23

    The invention provides synthetic heparin-binding growth factor analogs having at least one peptide chain that binds a heparin-binding growth factor receptor, covalently bound to a hydrophobic linker, which is in turn covalently bound to a non-signaling peptide that includes a heparin-binding domain. The synthetic heparin-binding growth factor analogs are useful as soluble biologics or as surface coatings for medical devices.

  9. Technetium-99m-d, 1-HM-PAO: a new radiopharmaceutical for imaging regional brain perfusion using SPECT--a comparison with iodine-123 HIPDM

    SciTech Connect

    Leonard, J.P.; Nowotnik, D.P.; Neirinckx, R.D.

    1986-12-01

    A new radiopharmaceutical, technetium-99m hexamethylpropyleneamine oxime (/sup 99m/Tc-d, 1-HM-PAO), has been reported to cross the blood-brain-barrier and to distribute in brain in proportion to regional blood flow. This study reports brain imaging obtained with /sup 99m/Tc-d,1 HM-PAO in 20 subjects; seven without evidence of cerebral disease and 13 with cerebrovascular disorders. In 16 patients comparative data were available with N,N,N'-trimethyl-N'-(2-hydroxy-3-methyl-5-iodobenzyl)-1,3-propanediamine ((/sup 123/I)HIPDM). Technetium-99m-d, 1-HM-PAO is retained sufficiently long to allow single photon emission computed tomography (SPECT) with widely available rotating gamma camera systems. The kinetics demonstrated a rapid brain uptake and prolonged retention of activity in cerebral structures. Good tomographic images are obtained with much higher uptake in gray than in white matter. Blood flow maps are comparable to those achieved with (/sup 123/I)HIPDM and established strokes were clearly seen, with similar details as in HIPDM studies. Delayed studies showed that the distribution in the brain remained virtually unchanged. Technetium-99m-d, 1-HM-PAO imaging appears particularly promising in routine examination of patients with cerebrovascular disorders.

  10. The first experience of using 99mTc-Al2O3-based radiopharmaceutical for the detection of sentinel lymph nodes in cervical cancer patients

    NASA Astrophysics Data System (ADS)

    Sinilkin, I. G.; Chernov, V. I.; Lyapunov, A. Yu.; Medvedeva, A. A.; Zelchan, R. V.; Chernyshova, A. L.; Kolomiets, L. A.

    2016-08-01

    The purpose of the study was to evaluate the feasibility of using 99mTc-Al2O3-based radiopharmaceutical, a novel molecular imaging agent for sentinel lymph node detection in patients with invasive cervical cancer. The study included 23 cervical cancer patients (T1aNxMx-T2bNxMx) treated at the Tomsk Cancer Research Institute. In the 18 hours before surgery, 80 MBq of the 99mTc-Al2O3 in peritumoral injected, followed by single-photon emission computed tomography (SPECT) of the pelvis and intraoperative SLN identification. Twenty-seven SLNs were detected by SPECT, and 34 SLNs were identified by intraoperative gamma probe. The total number of identified SLNs per patient ranged from 1 to 3 (the mean number of SLNs was 1.4 per patient). The most common site for SLN detection was the external iliac region (57.2%), followed by the internal iliac (14%), obturator (14%), presacral and retrosacral regions (14%), and the parametrial region (1%). Sensitivity in detecting SLNs was 100% for intraoperative SLN identification and 79% for SPECT image.

  11. Development of more efficacious Tc-99m organ imaging agents for use in nuclear medicine by analytical characterization of radiopharmaceutical mixtures

    SciTech Connect

    Heineman, W.R.

    1992-01-24

    The long-range objective of this research program is the development of more efficacious technetium-99m radiopharmaceuticals for use as imaging agents in diagnostic nuclear medicine. We seek to isolate and develop distinct site imaging agents, each of which has properties optimized to provide diagnostic information concerning a given pathological condition. The specific objectives during the period (9/1/89 to 8/31/92) include: (1) Development of strategies for improving yields of specific Tc-diphosphonate complexes with optimum imaging properties; (2) Development of electrodes for rapid in situ electrochemical generation of skeletal imaging agents; (3) Development of electrochemical sensors for {Tc} and Re imaging agents; (4) Characterization of stable {Tc}- and Re-diphosphonate complexes obtainable in high yield by structural studies with techniques such as NMR, EXAFS, and Raman spectroscopy; (5) Development of improved separation techniques for the characterization of diphosphonate skeletal imaging agents; (6) Evaluation of the effect of the biological milieu on {Tc}-diphosphonate complexes; and (7) Electrochemical studies of technetium and rhenium complexes synthesized by Professor Deutsch's research group for heart and brain imaging.

  12. The concept of minimum detectable activity of radionuclide activity meters and their suitability for routine quality control of radiopharmaceuticals. An experimental study.

    PubMed

    Zagni, F; Cesarini, F; Lucconi, G; Cicoria, G; Pancaldi, D; Infantino, A; Vichi, S; Marengo, M

    2016-07-01

    Radionuclide activity meters ("dose calibrators") are ionization chambers designed to measure relatively high amount of activities which are normally contained in radiopharmaceuticals. However, in the current radiopharmacy practice, these radiation detectors have been proposed to be used in measurements of samples with lower activity, such as in routine quality control (QC) tests. To check the feasibility of such measurements, in this work we assessed the performance of four different devices in the lower range of detectability, by means of experimental measurements of a radioactive sample. Accuracy and precision of each device was evaluated as a function of the activity contained in the sample in order to estimate a threshold value, or minimum detectable activity (MDA), which, according to our operational definition, may be used to express the concept of Limit of Quantification (LoQ). Moreover, a generalized procedure for the estimation of the MDA was established, which, being device- and radionuclide-independent, it may be adopted by every laboratory. Our results showed a significant variability in the MDA achieved by different activity meters. Hence a single QC test may result feasible with one specific instrument, and not with another one. Moreover, feasibility depends also on the confidence level required for each test. For these reasons, each activity meter should be qualified for its MDA or LoQ by each laboratory according to a procedure such as that described in this paper. PMID:27108071

  13. A novel device for automatic withdrawal and accurate calibration of 99m-technetium radiopharmaceuticals to minimise radiation exposure to nuclear medicine staff and patient.

    PubMed

    Nazififard, Mohammad; Mahdizadeh, Simin; Meigooni, A S; Alavi, M; Suh, Kune Y

    2012-09-01

    A Joint Automatic Dispenser Equipment (JADE) has been designed and fabricated for automatic withdrawal and calibration of radiopharmaceutical materials. The thermoluminescent dosemeter procedures have shown a reduction in dose to the technician's hand with this novel dose dispenser system JADE when compared with the manual withdrawal of (99m)Tc. This system helps to increase the precision of calibration and to minimise the radiation dose to the hands and body of the workers. This paper describes the structure of this device, its function and user-friendliness, and its efficacy. The efficacy of this device was determined by measuring the radiation dose delivered to the hands of the nuclear medicine laboratory technician. The user-friendliness of JADE has been examined. The automatic withdrawal and calibration offered by this system reduces the dose to the technician's hand to a level below the maximum permissible dose stipulated by the international protocols. This research will serve as a backbone for future study about the safe use of ionising radiation in medicine. PMID:22628527

  14. High Yield Production and Radiochemical Isolation of Isotopically Pure Arsenic-72 and Novel Radioarsenic Labeling Strategies for the Development of Theranostic Radiopharmaceuticals.

    PubMed

    Ellison, Paul A; Barnhart, Todd E; Chen, Feng; Hong, Hao; Zhang, Yin; Theuer, Charles P; Cai, Weibo; Nickles, Robert J; DeJesus, Onofre T

    2016-01-20

    Radioisotopes of arsenic are of considerable interest to the field of nuclear medicine with unique nuclear and chemical properties making them well-suited for use in novel theranostic radiopharmaceuticals. However, progress must still be made in the production of isotopically pure radioarsenic and in its stable conjugation to biological targeting vectors. This work presents the production and irradiation of isotopically enriched (72)Ge(m) discs in an irrigation-cooled target system allowing for the production of isotopically pure (72)As with capability on the order of 10 GBq. A radiochemical separation procedure isolated the reactive trivalent radioarsenic in a small volume buffered aqueous solution, while reclaiming (72)Ge target material. The direct thiol-labeling of a monoclonal antibody resulted in a conjugate exhibiting exceptionally poor in vivo stability in a mouse model. This prompted further investigations to alternative radioarsenic labeling strategies, including the labeling of the dithiol-containing chelator dihydrolipoic acid, and thiol-modified mesoporous silica nanoparticles (MSN-SH). Radioarsenic-labeled MSN-SH showed exceptional in vivo stability toward dearsenylation. PMID:26646989

  15. Positive Emotion Facilitates Audiovisual Binding

    PubMed Central

    Kitamura, Miho S.; Watanabe, Katsumi; Kitagawa, Norimichi

    2016-01-01

    It has been shown that positive emotions can facilitate integrative and associative information processing in cognitive functions. The present study examined whether emotions in observers can also enhance perceptual integrative processes. We tested 125 participants in total for revealing the effects of emotional states and traits in observers on the multisensory binding between auditory and visual signals. Participants in Experiment 1 observed two identical visual disks moving toward each other, coinciding, and moving away, presented with a brief sound. We found that for participants with lower depressive tendency, induced happy moods increased the width of the temporal binding window of the sound-induced bounce percept in the stream/bounce display, while no effect was found for the participants with higher depressive tendency. In contrast, no effect of mood was observed for a simple audiovisual simultaneity discrimination task in Experiment 2. These results provide the first empirical evidence of a dependency of multisensory binding upon emotional states and traits, revealing that positive emotions can facilitate the multisensory binding processes at a perceptual level. PMID:26834585

  16. Hebrew as a Binding Force.

    ERIC Educational Resources Information Center

    Fischler, Ben-Zion

    1990-01-01

    The role of the Hebrew language as a cohesive force and the history of modern Hebrew instruction are chronicled. It is proposed that despite the scattering of its speakers and periods of use only as a literary or business language, Hebrew has been a binding force for the Jewish people. It was with considerable struggle that Hebrew gained…

  17. Al(+)-ligand binding energies

    NASA Technical Reports Server (NTRS)

    Sodupe, M.; Bauschlicher, Charles W., Jr.

    1991-01-01

    Ab initio calculations are used to optimize the structure and determine the binding energies of Al(+) to a series of ligands. For Al(+)-CN, the bonding was found to have a large covalent component. For the remaining ligands, the bonding is shown to be electrostatic in origin. The results obtained for Al(+) are compared with those previously reported for Mg(+).

  18. Cellulose binding domain fusion proteins

    DOEpatents

    Shoseyov, O.; Yosef, K.; Shpiegl, I.; Goldstein, M.A.; Doi, R.H.

    1998-02-17

    A cellulose binding domain (CBD) having a high affinity for crystalline cellulose and chitin is disclosed, along with methods for the molecular cloning and recombinant production. Fusion products comprising the CBD and a second protein are likewise described. A wide range of applications are contemplated for both the CBD and the fusion products, including drug delivery, affinity separations, and diagnostic techniques. 16 figs.

  19. Cellulose binding domain fusion proteins

    DOEpatents

    Shoseyov, Oded; Shpiegl, Itai; Goldstein, Marc A.; Doi, Roy H.

    1998-01-01

    A cellulose binding domain (CBD) having a high affinity for crystalline cellulose and chitin is disclosed, along with methods for the molecular cloning and recombinant production thereof. Fusion products comprising the CBD and a second protein are likewise described. A wide range of applications are contemplated for both the CBD and the fusion products, including drug delivery, affinity separations, and diagnostic techniques.

  20. Protein binding assay for hyaluronate

    SciTech Connect

    Lacy, B.E.; Underhill, C.B.

    1986-11-01

    A relatively quick and simple assay for hyaluronate was developed using the specific binding protein, hyaluronectin. The hyaluronectin was obtained by homogenizing the brains of Sprague-Dawley rats, and then centrifuging the homogenate. The resulting supernatant was used as a source of crude hyaluronectin. In the binding assay, the hyaluronectin was mixed with (/sup 3/H)hyaluronate, followed by an equal volume of saturated (NH/sub 4/)/sub 2/SO/sub 4/, which precipitated the hyaluronectin and any (/sup 3/H)hyaluronate associated with it, but left free (/sup 3/H)hyaluronate in solution. The mixture was then centrifuged, and the amount of bound (/sup 3/H)hyaluronate in the precipitate was determined. Using this assay, the authors found that hyaluronectin specifically bound hyaluronate, since other glycosaminoglycans failed to compete for the binding protein. In addition, the interaction between hyaluronectin and hyaluronate was of relatively high affinity, and the size of the hyaluronate did not appear to substantially alter the amount of binding. To determine the amount of hyaluronate in an unknown sample, they used a competition assay in which the binding of a set amount of (/sup 3/H)hyaluronate was blocked by the addition of unlabeled hyaluronate. By comparing the degree of competition of the unknown samples with that of known amounts of hyaluronate, it was possible to determine the amount of hyaluronate in the unknowns. They have found that this method is sensitive to 1 ..mu..g or less of hyaluronate, and is unaffected by the presence of proteins.

  1. The prion protein binds thiamine.

    PubMed

    Perez-Pineiro, Rolando; Bjorndahl, Trent C; Berjanskii, Mark V; Hau, David; Li, Li; Huang, Alan; Lee, Rose; Gibbs, Ebrima; Ladner, Carol; Dong, Ying Wei; Abera, Ashenafi; Cashman, Neil R; Wishart, David S

    2011-11-01

    Although highly conserved throughout evolution, the exact biological function of the prion protein is still unclear. In an effort to identify the potential biological functions of the prion protein we conducted a small-molecule screening assay using the Syrian hamster prion protein [shPrP(90-232)]. The screen was performed using a library of 149 water-soluble metabolites that are known to pass through the blood-brain barrier. Using a combination of 1D NMR, fluorescence quenching and surface plasmon resonance we identified thiamine (vitamin B1) as a specific prion ligand with a binding constant of ~60 μM. Subsequent studies showed that this interaction is evolutionarily conserved, with similar binding constants being seen for mouse, hamster and human prions. Various protein construct lengths, both with and without the unstructured N-terminal region in the presence and absence of copper, were examined. This indicates that the N-terminus has no influence on the protein's ability to interact with thiamine. In addition to thiamine, the more biologically abundant forms of vitamin B1 (thiamine monophosphate and thiamine diphosphate) were also found to bind the prion protein with similar affinity. Heteronuclear NMR experiments were used to determine thiamine's interaction site, which is located between helix 1 and the preceding loop. These data, in conjunction with computer-aided docking and molecular dynamics, were used to model the thiamine-binding pharmacophore and a comparison with other thiamine binding proteins was performed to reveal the common features of interaction. PMID:21848803

  2. Development and characterization of a promising fluorine-18 labelled radiopharmaceutical for in vivo imaging of fatty acid amide hydrolase.

    PubMed

    Sadovski, Oleg; Hicks, Justin W; Parkes, Jun; Raymond, Roger; Nobrega, José; Houle, Sylvain; Cipriano, Mariateresa; Fowler, Christopher J; Vasdev, Neil; Wilson, Alan A

    2013-07-15

    Fatty acid amide hydrolase (FAAH), the enzyme responsible for terminating signaling by the endocannabinoid anandamide, plays an important role in the endocannabinoid system, and FAAH inhibitors are attractive drugs for pain, addiction, and neurological disorders. The synthesis, radiosynthesis, and evaluation, in vitro and ex vivo in rat, of an (18)F-radiotracer designed to image FAAH using positron emission tomography (PET) is described. Fluorine-18 labelled 3-(4,5-dihydrooxazol-2-yl)phenyl (5-fluoropentyl)carbamate, [(18)F]5, was synthesized at high specific activity in a one-pot three step reaction using a commercial module with a radiochemical yield of 17-22% (from [(18)F]fluoride). In vitro assay using rat brain homogenates showed that 5 inhibited FAAH in a time-dependent manner, with an IC50 value of 0.82nM after a preincubation of 60min. Ex vivo biodistribution studies and ex vivo autoradiography in rat brain demonstrated that [(18)F]5 had high brain penetration with standard uptake values of up to 4.6 and had a regional distribution which correlated with reported regional FAAH enzyme activity. Specificity of binding to FAAH with [(18)F]5 was high (>90%) as demonstrated by pharmacological challenges with potent and selective FAAH inhibitors and was irreversible as demonstrated by radioactivity measurements on homogenized brain tissue extracts. We infer from these results that [(18)F]5 is a highly promising candidate radiotracer with which to image FAAH in human subjects using PET and clinical studies are proceeding. PMID:23712084

  3. Mg(+)-ligand binding energies

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles W., Jr.; Partridge, Harry

    1991-01-01

    Ab initio calculations are used to optimize the structures and determine the binding energies of Mg(+) to a series of ligands. Mg(+) bonds electrostatically with benzene, acetone, H2, CO, and NH3 and a self-consistent-field treatment gives a good description of the bonding. The bonding in MgCN(+) and MgCH3(+) is largely covalent and a correlated treatment is required.

  4. Anion binding in biological systems

    NASA Astrophysics Data System (ADS)

    Feiters, Martin C.; Meyer-Klaucke, Wolfram; Kostenko, Alexander V.; Soldatov, Alexander V.; Leblanc, Catherine; Michel, Gurvan; Potin, Philippe; Küpper, Frithjof C.; Hollenstein, Kaspar; Locher, Kaspar P.; Bevers, Loes E.; Hagedoorn, Peter-Leon; Hagen, Wilfred R.

    2009-11-01

    We compare aspects of biological X-ray absorption spectroscopy (XAS) studies of cations and anions, and report on some examples of anion binding in biological systems. Brown algae such as Laminaria digitata (oarweed) are effective accumulators of I from seawater, with tissue concentrations exceeding 50 mM, and the vanadate-containing enzyme haloperoxidase is implicated in halide accumulation. We have studied the chemical state of iodine and its biological role in Laminaria at the I K edge, and bromoperoxidase from Ascophyllum nodosum (knotted wrack) at the Br K edge. Mo is essential for many forms of life; W only for certain archaea, such as Archaeoglobus fulgidus and the hyperthermophilic archaeon Pyrococcus furiosus, and some bacteria. The metals are bound and transported as their oxo-anions, molybdate and tungstate, which are similar in size. The transport protein WtpA from P. furiosus binds tungstate more strongly than molybdate, and is related in sequence to Archaeoglobus fulgidus ModA, of which a crystal structure is known. We have measured A. fulgidus ModA with tungstate at the W L3 (2p3/2) edge, and compared the results with the refined crystal structure. XAS studies of anion binding are feasible even if only weak interactions are present, are biologically relevant, and give new insights in the spectroscopy.

  5. Bone-Targeting Radiopharmaceuticals for the Treatment of Bone-Metastatic Castration-Resistant Prostate Cancer: Exploring the Implications of New Data

    PubMed Central

    Saylor, Philip J.; Everly, Jason J.; Sartor, Oliver

    2014-01-01

    Background. Clinical features of patients with castration-resistant prostate cancer (CRPC) are characterized by a high incidence of bone metastases, which are associated with impairment of quality of life, pain, skeletal-related events (SREs), and a negative impact on prognosis. Advances in the understanding of cancer cell-bone stroma interactions and molecular mechanisms have recently permitted the development of new agents. Purpose. We review the merits, applications, and limitations of emerging data sets on bone-metastatic CRPC with a focus on radium-223, an α-emitting radiopharmaceutical, and its use in therapy for this disease. Methods. References for this review were identified through searches of PubMed and Medline databases, and only papers published in English were considered. Related links in the databases were reviewed, along with relevant published guidelines, recently published abstracts from major medical meetings, and transcripts from a recent round table of clinical investigators. Results. Prior to radium-223, available bone-targeted therapies demonstrated the ability to delay SREs and palliate bone pain in patients with metastatic CRPC but without evidence of improvement in overall survival (OS). In a randomized controlled phase III trial, radium-223 demonstrated the ability to improve OS and delay SREs in docetaxel-pretreated or docetaxel-unfit men with symptomatic bone-metastatic CRPC and was not associated with significantly more grade 3 or 4 adverse events than placebo. Conclusion. Radium-223 has a targeted effect on bone metastases in CRPC and has an important role in docetaxel-pretreated or docetaxel-unfit men with symptomatic bone-metastatic CRPC. PMID:25232039

  6. Production, biodistribution, and dosimetry of 47Sc-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetramethylene phosphonic acid as a bone-seeking radiopharmaceutical

    PubMed Central

    Fathi, Fatemeh; Moghaddam-Banaem, Leila; Shamsaei, Mojtaba; Samani, Ali; Maragheh, Mohammad G.

    2015-01-01

    In this study 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetramethylene phosphonic acid (DOTMP) was used as the polyaminophosphonic acid carrier ligand and the therapeutic potential of the bone seeking radiopharmaceutical 47Sc-DOTMP was assessed by measuring its dosage–dependent skeletal uptake and then the absorbed radiation dose of human organs was estimated. Because of limited availability of 47Sc we performed some preliminary studies using 46Sc. 46Sc was produced with a specific activity of 116.58 MBq/mg (3.15 mCi/mg) and radionuclide purity of 98%. 46Sc-DOTMP was prepared and an activity of 1.258 MBq (34 μCi) at a chelant-to-metal ratio of 60:1 was administered to five groups of mice with each group containing 3 mice that were euthanized at 4, 24, 48, 96 and 192 h post administration. The heart, lungs, liver, spleen, kidneys, intestine, skin, muscle, and a femur were excised, weighed, and counted. The data were analyzed to determine skeletal uptake and source organ residence times and cumulated activities for 47Sc-DOTMP. 46Sc-DOTMP complex was prepared in radiochemical purity about 93%. In vitro stability of complex was evaluated at room temperature for 48 h. Biodistribution studies of complex in mice were studied for 7 days. The data were analyzed to estimate skeletal uptake and absorbed radiation dose of human organs using biodistribution data from mice. By considering the results, 47Sc-DOTMP is a possible therapeutic agent for using in palliation of bone pain due to metastatic skeletal lesions from several types of primary cancers in prostate, breast, etc. PMID:26500402

  7. Erythropoietin binding protein from mammalian serum

    DOEpatents

    Clemons, G.K.

    1997-04-29

    Purified mammalian erythropoietin binding-protein is disclosed, and its isolation, identification, characterization, purification, and immunoassay are described. The erythropoietin binding protein can be used for regulation of erythropoiesis by regulating levels and half-life of erythropoietin. A diagnostic kit for determination of level of erythropoietin binding protein is also described. 11 figs.

  8. Erythropoietin binding protein from mammalian serum

    DOEpatents

    Clemons, Gisela K.

    1997-01-01

    Purified mammalian erythropoietin binding-protein is disclosed, and its isolation, identification, characterization, purification, and immunoassay are described. The erythropoietin binding protein can be used for regulation of erythropoiesis by regulating levels and half-life of erythropoietin. A diagnostic kit for determination of level of erythropoietin binding protein is also described.

  9. Feature-Based Binding and Phase Theory

    ERIC Educational Resources Information Center

    Antonenko, Andrei

    2012-01-01

    Current theories of binding cannot provide a uniform account for many facts associated with the distribution of anaphors, such as long-distance binding effects and the subject-orientation of monomorphemic anaphors. Further, traditional binding theory is incompatible with minimalist assumptions. In this dissertation I propose an analysis of…

  10. Evolution of Protein-binding DNA Sequences through Competitive Binding

    NASA Astrophysics Data System (ADS)

    Peng, Weiqun; Gerland, Ulrich; Hwa, Terence; Levine, Herbert

    2002-03-01

    The dynamics of in vitro DNA evolution controlled via competitive binding of DNA sequences to proteins has been explored in a recent serial transfer experiment footnote B. Dubertret, S.Liu, Q. Ouyang, A. Libchaber, Phys. Rev. Lett. 86, 6022 (2001).. Motivated by the experiment, we investigate a continuum model for this evolution process in various parameter regimes. We establish a self-consistent mean-field evolution equation, determine its dynamical properties and finite population size corrections. In addition, we discuss the experimental implications of our results.

  11. Synthetic heparin-binding factor analogs

    DOEpatents

    Pena, Louis A.; Zamora, Paul O.; Lin, Xinhua; Glass, John D.

    2010-04-20

    The invention provides synthetic heparin-binding growth factor analogs having at least one peptide chain, and preferably two peptide chains branched from a dipeptide branch moiety composed of two trifunctional amino acid residues, which peptide chain or chains bind a heparin-binding growth factor receptor and are covalently bound to a non-signaling peptide that includes a heparin-binding domain, preferably by a linker, which may be a hydrophobic linker. The synthetic heparin-binding growth factor analogs are useful as pharmaceutical agents, soluble biologics or as surface coatings for medical devices.

  12. Localization of the chaperone binding site

    NASA Technical Reports Server (NTRS)

    Boyle, D.; Gopalakrishnan, S.; Takemoto, L.; Spooner, B. S. (Principal Investigator)

    1993-01-01

    The hypothesis derived from models of the multi-oligomeric chaperone complex suggests that partially denatured proteins bind in a central cavity in the aggregate. To test this hypothesis, the molecular chaperone, alpha crystallin, was bound to partially denatured forms of gamma crystallin, and the binding site was visualized by immunogold localization. In an alternative approach, gold particles were directly complexed with gamma crystallin, followed by binding to the alpha crystallin aggregate. In both cases, binding was localized to the central region of the aggregate, confirming for the first time that partially denatured proteins do indeed bind to a central region of the molecular chaperone aggregate.

  13. Unraveling determinants of transcription factor binding outside the core binding site.

    PubMed

    Levo, Michal; Zalckvar, Einat; Sharon, Eilon; Dantas Machado, Ana Carolina; Kalma, Yael; Lotam-Pompan, Maya; Weinberger, Adina; Yakhini, Zohar; Rohs, Remo; Segal, Eran

    2015-07-01

    Binding of transcription factors (TFs) to regulatory sequences is a pivotal step in the control of gene expression. Despite many advances in the characterization of sequence motifs recognized by TFs, our ability to quantitatively predict TF binding to different regulatory sequences is still limited. Here, we present a novel experimental assay termed BunDLE-seq that provides quantitative measurements of TF binding to thousands of fully designed sequences of 200 bp in length within a single experiment. Applying this binding assay to two yeast TFs, we demonstrate that sequences outside the core TF binding site profoundly affect TF binding. We show that TF-specific models based on the sequence or DNA shape of the regions flanking the core binding site are highly predictive of the measured differential TF binding. We further characterize the dependence of TF binding, accounting for measurements of single and co-occurring binding events, on the number and location of binding sites and on the TF concentration. Finally, by coupling our in vitro TF binding measurements, and another application of our method probing nucleosome formation, to in vivo expression measurements carried out with the same template sequences serving as promoters, we offer insights into mechanisms that may determine the different expression outcomes observed. Our assay thus paves the way to a more comprehensive understanding of TF binding to regulatory sequences and allows the characterization of TF binding determinants within and outside of core binding sites. PMID:25762553

  14. Infinite sets and double binds.

    PubMed

    Arden, M

    1984-01-01

    There have been many attempts to bring psychoanalytical theory up to date. This paper approaches the problem by discussing the work of Gregory Bateson and Ignacio Matte-Blanco, with particular reference to the use made by these authors of Russell's theory of logical types. Bateson's theory of the double bind and Matte-Blanco's bilogic are both based on concepts of logical typing. It is argued that the two theories can be linked by the idea that neurotic symptoms are based on category errors in thinking. Clinical material is presented from the analysis of a middle-aged woman. The intention is to demonstrate that the process of making interpretations can be thought of as revealing errors in thinking. Changes in the patient's inner world are then seen to be the result of clarifying childhood experiences based on category errors. Matte-Blanco's theory of bilogic and infinite experiences is a re-evaluation of the place of the primary process in mental life. It is suggested that a combination of bilogic and double bind theory provides a possibility of reformulating psychoanalytical theory. PMID:6544755

  15. Comparing binding site information to binding affinity reveals that Crp/DNA complexes have several distinct binding conformers

    PubMed Central

    Holmquist, Peter C.; Holmquist, Gerald P.; Summers, Michael L.

    2011-01-01

    We show that the cAMP receptor protein (Crp) binds to DNA as several different conformers. This situation has precluded discovering a high correlation between any sequence property and binding affinity for proteins that bend DNA. Experimentally quantified affinities of Synechocystis sp. PCC 6803 cAMP receptor protein (SyCrp1), the Escherichia coli Crp (EcCrp, also CAP) and DNA were analyzed to mathematically describe, and make human-readable, the relationship of DNA sequence and binding affinity in a given system. Here, sequence logos and weight matrices were built to model SyCrp1 binding sequences. Comparing the weight matrix model to binding affinity revealed several distinct binding conformations. These Crp/DNA conformations were asymmetrical (non-palindromic). PMID:21586590

  16. Nucleotide-binding mechanisms in pseudokinases

    PubMed Central

    Hammarén, Henrik M.; Virtanen, Anniina T.; Silvennoinen, Olli

    2015-01-01

    Pseudokinases are classified by the lack of one or several of the highly conserved motifs involved in nucleotide (nt) binding or catalytic activity of protein kinases (PKs). Pseudokinases represent ∼10% of the human kinome and they are found in all evolutionary classes of kinases. It has become evident that pseudokinases, which were initially considered somewhat peculiar dead kinases, are important components in several signalling cascades. Furthermore, several pseudokinases have been linked to human diseases, particularly cancer, which is raising interest for therapeutic approaches towards these proteins. The ATP-binding pocket is a well-established drug target and elucidation of the mechanism and properties of nt binding in pseudokinases is of significant interest and importance. Recent studies have demonstrated that members of the pseudokinase family are very diverse in structure as well as in their ability and mechanism to bind nts or perform phosphoryl transfer reactions. This diversity also precludes prediction of pseudokinase function, or the importance of nt binding for said function, based on primary sequence alone. Currently available data indicate that ∼40% of pseudokinases are able to bind nts, whereas only few are able to catalyse occasional phosphoryl transfer. Pseudokinases employ diverse mechanisms to bind nts, which usually occurs at low, but physiological, affinity. ATP binding serves often a structural role but in most cases the functional roles are not precisely known. In the present review, we discuss the various mechanisms that pseudokinases employ for nt binding and how this often low-affinity binding can be accurately analysed. PMID:26589967

  17. Receptor-binding sites: bioinformatic approaches.

    PubMed

    Flower, Darren R

    2006-01-01

    It is increasingly clear that both transient and long-lasting interactions between biomacromolecules and their molecular partners are the most fundamental of all biological mechanisms and lie at the conceptual heart of protein function. In particular, the protein-binding site is the most fascinating and important mechanistic arbiter of protein function. In this review, I examine the nature of protein-binding sites found in both ligand-binding receptors and substrate-binding enzymes. I highlight two important concepts underlying the identification and analysis of binding sites. The first is based on knowledge: when one knows the location of a binding site in one protein, one can "inherit" the site from one protein to another. The second approach involves the a priori prediction of a binding site from a sequence or a structure. The full and complete analysis of binding sites will necessarily involve the full range of informatic techniques ranging from sequence-based bioinformatic analysis through structural bioinformatics to computational chemistry and molecular physics. Integration of both diverse experimental and diverse theoretical approaches is thus a mandatory requirement in the evaluation of binding sites and the binding events that occur within them. PMID:16671408

  18. 177Lu-DO3A-HSA-Z EGFR:1907: characterization as a potential radiopharmaceutical for radionuclide therapy of EGFR-expressing head and neck carcinomas.

    PubMed

    Hoppmann, Susan; Qi, Shibo; Miao, Zheng; Liu, Hongguang; Jiang, Han; Cutler, Cathy S; Bao, Ande; Cheng, Zhen

    2012-06-01

    Epidermal growth factor receptor 1 (EGFR) is an attractive target for radionuclide therapy of head and neck carcinomas. Affibody molecules against EGFR (Z(EGFR)) show excellent tumor localizations in imaging studies. However, one major drawback is that radiometal-labeled Affibody molecules display extremely high uptakes in the radiosensitive kidneys which may impact their use as radiotherapeutic agents. The purpose of this study is to further explore whether radiometal-labeled human serum albumin (HSA)-Z(EFGR) bioconjugates display desirable profiles for the use in radionuclide therapy of EGFR-positive head and neck carcinomas. The Z(EFGR) analog, Ac-Cys-Z(EGFR:1907), was site-specifically conjugated with HSA. The resulting bioconjugate 1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid (DO3A)-HSA-Z(EGFR:1907) was then radiolabeled with either (64)Cu or (177)Lu and subjected to in vitro cell uptake and internalization studies using the human oral squamous carcinoma cell line SAS. Positron emission tomography (PET), single photon emission computed tomography (SPECT), and biodistribution studies were conducted using SAS-tumor-bearing mice. Cell studies revealed a high (8.43 ± 0.55 % at 4 h) and specific (0.95 ± 0.09 % at 4 h) uptake of (177)Lu-DO3A-HSA-Z(EGFR:1907) as determined by blocking with nonradioactive Z(EGFR:1907). The internalization of (177)Lu-DO3A-HSA-Z(EGFR:1907) was verified in vitro and found to be significantly higher than that of (177)Lu-labeled Z(EFGR) at 2-24 h of incubation. PET and SPECT studies showed good tumor imaging contrasts. The biodistribution of (177)Lu-DO3A-HSA-Z(EGFR:1907) in SAS-tumor-bearing mice displayed high tumor uptake (5.1 ± 0.44 % ID/g) and liver uptake (31.5 ± 7.66 % ID/g) and moderate kidney uptake (8.5 ± 1.08 % ID/g) at 72 h after injection. (177)Lu-DO3A-HSA-Z(EGFR:1907) shows promising in vivo profiles and may be a potential radiopharmaceutical for radionuclide therapy of EGFR-expressing head and neck carcinomas

  19. Comparative efficacy, tolerability, and survival outcomes of various radiopharmaceuticals in castration-resistant prostate cancer with bone metastasis: a meta-analysis of randomized controlled trials

    PubMed Central

    Tunio, Mutahir; Al Asiri, Mushabbab; Al Hadab, Abdulrehman; Bayoumi, Yasser

    2015-01-01

    Background A meta-analysis was conducted to assess the impact of radiopharmaceuticals (RPs) in castration-resistant prostate cancer (CRPC) on pain control, symptomatic skeletal events (SSEs), toxicity profile, quality of life (QoL), and overall survival (OS). Materials and methods The PubMed/MEDLINE, CANCERLIT, EMBASE, Cochrane Library database, and other search engines were searched to identify randomized controlled trials (RCTs) comparing RPs with control (placebo or radiation therapy) in metastatic CRPC. Data were extracted and assessed for the risk of bias (Cochrane’s risk of bias tool). Pooled data were expressed as odds ratio (OR), with 95% confidence intervals (CIs; Mantel–Haenszel fixed-effects model). Results Eight RCTs with a total patient population of 1,877 patients were identified. The use of RP was associated with significant reduction in pain intensity and SSE (OR: 0.63, 95% CI: 0.51–0.78, I2=27%, P,0.0001), improved QoL (OR: 0.71, 95% CI: 0.55–0.91, I2=65%, three trials, 1,178 patients, P=0.006), and a minimal improved OS (OR: 0.84, 95% CI: 0.64–1.04, I2=47%, seven trials, 1,845 patients, P=0.11). A subgroup analysis suggested an improved OS with radium-223 (OR: 0.68, 95% CI: 0.51–0.90, one trial, 921 patients) and strontium-89 (OR: 0.21, 95% CI: 0.05–0.91, one trial, 49 patients). Strontium-89 (five trials) was associated with increased rates of grade 3 and 4 thrombocytopenia (OR: 4.26, 95% CI: 2.22–8.18, P=0.01), leucopenia (OR: 7.98, 95% CI: 1.82–34.95, P=0.02), pain flare (OR: 6.82, 95% CI: 3.42–13.55, P=0.04), and emesis (OR: 3.61, 95% CI: 1.76–7.40, P=0.02). Conclusion The use of RPs was associated with significant reduction in SSEs and improved QoL, while the radium-223-related OS benefit warrants further large, RCTs in docetaxel naive metastatic CRPC patients. PMID:26451085

  20. Synthetic LPS-Binding Polymer Nanoparticles

    NASA Astrophysics Data System (ADS)

    Jiang, Tian

    Lipopolysaccharide (LPS), one of the principal components of most gram-negative bacteria's outer membrane, is a type of contaminant that can be frequently found in recombinant DNA products. Because of its strong and even lethal biological effects, selective LPS removal from bioproducts solution is of particular importance in the pharmaceutical and health care industries. In this thesis, for the first time, a proof-of-concept study on preparing LPS-binding hydrogel-like NPs through facile one-step free-radical polymerization was presented. With the incorporation of various hydrophobic (TBAm), cationic (APM, GUA) monomers and cross-linkers (BIS, PEG), a small library of NPs was constructed. Their FITC-LPS binding behaviors were investigated and compared with those of commercially available LPS-binding products. Moreover, the LPS binding selectivity of the NPs was also explored by studying the NPs-BSA interactions. The results showed that all NPs obtained generally presented higher FITC-LPS binding capacity in lower ionic strength buffer than higher ionic strength. However, unlike commercial poly-lysine cellulose and polymyxin B agarose beads' nearly linear increase of FITC-LPS binding with particle concentration, NPs exhibited serious aggregation and the binding quickly saturated or even decreased at high particle concentration. Among various types of NPs, higher FITC-LPS binding capacity was observed for those containing more hydrophobic monomers (TBAm). However, surprisingly, more cationic NPs with higher content of APM exhibited decreased FITC-LPS binding in high ionic strength conditions. Additionally, when new cationic monomer and cross-linker, GUA and PEG, were applied to replace APM and BIS, the obtained NPs showed improved FITC-LPS binding capacity at low NP concentration. But compared with APM- and BIS-containing NPs, the FITC-LPS binding capacity of GUA- and PEG-containing NPs saturated earlier. To investigate the NPs' binding to proteins, we tested the NPs

  1. DNA Binding Hydroxyl Radical Probes

    PubMed Central

    Tang, Vicky J; Konigsfeld, Katie M; Aguilera, Joe A; Milligan, Jamie R

    2011-01-01

    The hydroxyl radical is the primary mediator of DNA damage by the indirect effect of ionizing radiation. It is a powerful oxidizing agent produced by the radiolysis of water and is responsible for a significant fraction of the DNA damage associated with ionizing radiation. There is therefore an interest in the development of sensitive assays for its detection. The hydroxylation of aromatic groups to produce fluorescent products has been used for this purpose. We have examined four different chromophores which produce fluorescent products when hydroxylated. Of these, the coumarin system suffers from the fewest disadvantages. We have therefore examined its behavior when linked to a cationic peptide ligand designed to bind strongly to DNA. PMID:22125376

  2. Hemoglobin binding to deglycosylated haptoglobin.

    PubMed

    Kaartinen, V; Mononen, I

    1988-04-14

    The carbohydrate portion of polymeric haptoglobin was gradually removed by exoglycosidases in order to investigate its role in complex formation between haptoglobin and hemoglobin. Total removal of sialic acid diminished the haptoglobin-hemoglobin complex formation 15%. Removal of about 25% of the galactose residues from asialohaptoglobin, i.e., about 40% of the total weight of the carbohydrate moiety, totally inhibited the ability of haptoglobin to form complex with hemoglobin and react with haptoglobin-specific antibodies. Liberation of further galactose residues resulted in slow precipitation of the protein. Removal of a similar part of the carbohydrate moiety from haptoglobin-hemoglobin complex did not liberate hemoglobin from it, and the complex reacted with haptoglobin antibodies. The combined data indicate that the carbohydrate portion is essential for the functionally active form of polymeric haptoglobin to complex with hemoglobin, but it hardly has any direct role in the binding event, and other factors are responsible for the stability of the complex. PMID:3128331

  3. Secretin: specific binding to rat brain membranes

    SciTech Connect

    Fremeau, R.T. Jr.; Jensen, R.T.; Charlton, C.G.; Miller, R.L.; O'Donohue, T.L.; Moody, T.W.

    1983-08-01

    The binding of (/sup 125/I)secretin to rat brain membranes was investigated. Radiolabeled secretin bound with high affinity (KD . 0.2 nM) to a single class of noninteracting sites. Binding was specific, saturable, and reversible. Regional distribution studies indicated that the specific binding was greatest in the cerebellum, intermediate in the cortex, thalamus, striatum, hippocampus, and hypothalamus, and lowest in the midbrain and medulla/pons. Pharmacological studies indicated that only secretin, but not other peptides, inhibits binding of (/sup 125/I)secretin with high affinity. Also, certain guanine nucleotides inhibited high affinity binding. These data indicate that rat brain membranes possess high affinity binding sites specific for secretin and that with the use of (/sup 125/I) secretin the kinetics, stoichiometry, specificity, and distribution of secretin receptors can be directly investigated.

  4. An RNA motif that binds ATP

    NASA Technical Reports Server (NTRS)

    Sassanfar, M.; Szostak, J. W.

    1993-01-01

    RNAs that contain specific high-affinity binding sites for small molecule ligands immobilized on a solid support are present at a frequency of roughly one in 10(10)-10(11) in pools of random sequence RNA molecules. Here we describe a new in vitro selection procedure designed to ensure the isolation of RNAs that bind the ligand of interest in solution as well as on a solid support. We have used this method to isolate a remarkably small RNA motif that binds ATP, a substrate in numerous biological reactions and the universal biological high-energy intermediate. The selected ATP-binding RNAs contain a consensus sequence, embedded in a common secondary structure. The binding properties of ATP analogues and modified RNAs show that the binding interaction is characterized by a large number of close contacts between the ATP and RNA, and by a change in the conformation of the RNA.

  5. Binding of TH-iloprost to rat gastric mucosa: a pitfall in performing radioligand binding assays

    SciTech Connect

    Beinborn, M.; Kromer, W.; Staar, U.; Sewing, K.F.

    1985-09-01

    Binding of TH-iloprost was studied in a 20,000 x g sediment of the rat gastric mucosa. When pH in both test tubes for total and non-specific binding was kept identical, no displaceable binding of iloprost could be detected. When no care was taken to keep the pH identical in corresponding test tubes of the binding assay, changes in pH simulated specific and displaceable binding of iloprost. Therefore it is concluded that - in contrast to earlier reports - it is not possible to demonstrate specific iloprost binding using the given method.

  6. Calcium-binding proteins and development

    NASA Technical Reports Server (NTRS)

    Beckingham, K.; Lu, A. Q.; Andruss, B. F.; McIntire, L. V. (Principal Investigator)

    1998-01-01

    The known roles for calcium-binding proteins in developmental signaling pathways are reviewed. Current information on the calcium-binding characteristics of three classes of cell-surface developmental signaling proteins (EGF-domain proteins, cadherins and integrins) is presented together with an overview of the intracellular pathways downstream of these surface receptors. The developmental roles delineated to date for the universal intracellular calcium sensor, calmodulin, and its targets, and for calcium-binding regulators of the cytoskeleton are also reviewed.

  7. Binding Efficiency of Protein-Protein Complexes

    PubMed Central

    Day, Eric S.; Cote, Shaun M.; Whitty, Adrian

    2012-01-01

    We examine the relationship between binding affinity and interface size for reversible protein-protein interactions (PPI), using cytokines from the tumor necrosis factor (TNF) superfamily and their receptors as a test case. Using surface plasmon resonance, we measured single-site binding affinities for the large receptor TNFR1 binding to its ligands TNFα (KD = 1.4 ± 0.4 nM) and lymphotoxin-α (KD = 50 ± 10 nM), and also for the small receptor Fn14 binding to TWEAK (KD = 70 ± 10 nM). We additionally assembled data for all other TNF/TNFR family complexes for which reliable single site binding affinities have been reported. We used these values to calculate the binding efficiency – defined as binding energy per Å2 of surface area buried at the contact interface – for the nine of these complexes for which co-crystal structures are available, and compared the results to those for a set of 144 protein-protein complexes with published affinity values. The results show that the most efficient PPI complexes generate ~20 cal.mol−1/Å2 of binding energy. A minimum contact area of ~500 Å2 is required for a stable complex, required to generate sufficient interaction energy to pay the entropic cost of co-localizing two proteins from 1 M solution. The most compact and efficient TNF/TNFR complex was BAFF/BR3, which achieved ~80% of the maximum achievable binding efficiency. Other small receptors also gave high binding efficiencies, while the larger receptors generated only 44-49% of this limit despite interacting primarily through just a single small domain. The results provide new insight into how much binding energy can be generated by a PPI interface of a given size, and establish a quantitative method to predict how large a natural or engineered contact interface must be to achieve a given level of binding affinity. PMID:23088250

  8. Mutated Leguminous Lectin Containing a Heparin-Binding like Motif in a Carbohydrate-Binding Loop Specifically Binds to Heparin

    PubMed Central

    Abo, Hirohito; Soga, Keisuke; Tanaka, Atsuhiro; Tateno, Hiroaki; Hirabayashi, Jun; Yamamoto, Kazuo

    2015-01-01

    We previously introduced random mutations in the sugar-binding loops of a leguminous lectin and screened the resulting mutated lectins for novel specificities using cell surface display. Screening of a mutated peanut agglutinin (PNA), revealed a mutated PNA with a distinct preference for heparin. Glycan microarray analyses using the mutated lectin fused to the Fc region of human immunoglobulin, revealed that a particular sulfated glycosaminoglycan (GAG), heparin, had the highest binding affinity for mutated PNA among 97 glycans tested, although wild-type PNA showed affinity towards Galβ1-3GalNAc and similar galactosylated glycans. Further analyses of binding specificity using an enzyme-linked immunoadsorbent assay demonstrated that the mutated PNA specifically binds to heparin, and weakly to de-2-O-sulfated heparin, but not to other GAG chains including de-6-O-sulfated and de-N-sulfated heparins. The mutated PNA had six amino acid substitutions within the eight amino acid-long sugar-binding loop. In this loop, the heparin-binding like motif comprised three arginine residues at positions 124, 128, and 129, and a histidine at position 125 was present. Substitution of each arginine or histidine residue to alanine reduced heparin-binding ability, indicating that all of these basic amino acid residues contributed to heparin binding. Inhibition assay demonstrated that heparin and dextran sulfate strongly inhibited mutated PNA binding to heparin in dose-dependent manner. The mutated PNA could distinguish between CHO cells and proteoglycan-deficient mutant cells. This is the first report establishing a novel leguminous lectin that preferentially binds to highly sulfated heparin and may provide novel GAG-binding probes to distinguish between heterogeneous GAG repeating units. PMID:26714191

  9. Radiation abolishes inducer binding to lactose repressor.

    PubMed

    Gillard, Nathalie; Spotheim-Maurizot, Mélanie; Charlier, Michel

    2005-04-01

    The lactose operon functions under the control of the repressor-operator system. Binding of the repressor to the operator prevents the expression of the structural genes. This interaction can be destroyed by the binding of an inducer to the repressor. If ionizing radiations damage the partners, a dramatic dysfunction of the regulation system may be expected. We showed previously that gamma irradiation hinders repressor-operator binding through protein damage. Here we show that irradiation of the repressor abolishes the binding of the gratuitous inducer isopropyl-1-beta-D-thiogalactoside (IPTG) to the repressor. The observed lack of release of the repressor from the complex results from the loss of the ability of the inducer to bind to the repressor due to the destruction of the IPTG binding site. Fluorescence measurements show that both tryptophan residues located in or near the IPTG binding site are damaged. Since tryptophan damage is strongly correlated with the loss of IPTG binding ability, we conclude that it plays a critical role in the effect. A model was built that takes into account the kinetic analysis of damage production and the observed protection of its binding site by IPTG. This model satisfactorily accounts for the experimental results and allows us to understand the radiation-induced effects. PMID:15799700

  10. Evolution of Protein Binding Modes in Homooligomers

    PubMed Central

    Dayhoff, Judith E.; Shoemaker, Benjamin A.; Bryant, Stephen H.; Panchenko, Anna R.

    2009-01-01

    The evolution of protein interactions cannot be deciphered without a detailed analysis of interaction interfaces and binding modes. We performed a large-scale study of protein homooligomers in terms of their symmetry, interface sizes, and conservation of binding modes. We also focused specifically on the evolution of protein binding modes from nine families of homooligomers and mapped 60 different binding modes and oligomerization states onto the phylogenetic trees of these families. We observed a significant tendency for the same binding modes to be clustered together and conserved within clades on phylogenetic trees; this trend is especially pronounced for close homologs with 70% sequence identity or higher. Some binding modes are conserved among very distant homologs, pointing to their ancient evolutionary origin, while others are very specific for a certain phylogenetic group. Moreover, we found that the most ancient binding modes have a tendency to involve symmetrical (isologous) homodimer binding arrangements with larger interfaces, while recently evolved binding modes more often exhibit asymmetrical arrangements and smaller interfaces. PMID:19879880

  11. Fundamental considerations in ski binding analysis.

    PubMed

    Mote, C D; Hull, M L

    1976-01-01

    1. The static adjustment of a ski binding by hand or by available machines is only an adjustment and is neither a static nor a dynamic evaluation of the binding design. Bindings of different design with identical static adjustments will perform differently in environments in which the forces are static or dynamic. 2. The concept of binding release force is a useful measure of binding adjustment, but it is inappropriate as a criterion for binding evaluation. First, it does not direct attention toward the injury causing mechanism, strain, or displacement in the leg. Second, it is only part of the evaluation in dynamic problems. 3. The binding release decision in present bindings is displacement controlled. The relative displacement of the boot and ski is the system variable. For any specified relative displacement the binding force can be any of an infinite number of possibilities determined by the loading path. 4. The response of the leg-ski system to external impulses applied to the ski is independent of the boot-ski relative motion as long as the boot recenters quickly in the binding. Response is dependent upon the external impulse plus system inertia, damping and stiffness. 5. When tested under half sinusoidal forces applied to a test ski, all bindings will demonstrate static and impulse loading regions. In the static region the force drives the binding to a relative release displacement. In the impulse region the initial velocity of the ski drives the binding to a release displacement. 6. The transition between the static and impulse loading regions is determined by the binding's capacity to store and dissipate energy along the principal loading path. Increased energy capacity necessitates larger external impulses to produce release. 7. In all bindings examined to date, the transmitted leg displacement or strain at release under static loading exceeds leg strain under dynamic or impact loading. Because static loading is responsible for many injuries, a skier

  12. Lack of [3H]quinuclidinyl benzylate binding to biologically relevant binding sites on mononuclear cells.

    PubMed

    Adams, E M; Lubrano, T M; Gordon, J; Fields, J Z

    1992-09-01

    We analyzed the binding characteristics of [3H]quinuclidinyl benzylate ([3H]QNB), a muscarinic cholinergic ligand, to rat and human mononuclear cells (MNC). Under various assay conditions, atropine-sensitive, saturable binding occurred with an apparent Kd of 10 nM. Conditions which disrupted the MNC membrane reduced total binding and eliminated specific binding. Muscarinic agonists were unable to inhibit [3H]QNB binding to MNC at concentrations up to 10(-2) M. Stereoisomers dexetimide and levetimide were equipotent inhibitors of binding (IC50 2 x 10(-5) M). We conclude that, although atropine-sensitive binding of [3H]QNB to MNC occurs, the binding is not consistent with the presence of a biologically relevant muscarinic cholinergic receptor. PMID:1392105

  13. New DNA-binding radioprotectors

    NASA Astrophysics Data System (ADS)

    Martin, Roger

    The normal tissue damage associated with cancer radiotherapy has motivated the development at Peter Mac of a new class of DNA-binding radioprotecting drugs that could be applied top-ically to normal tissues at risk. Methylproamine (MP), the lead compound, reduces radiation induced cell kill at low concentrations. For example, experiments comparing the clonogenic survival of transformed human keratinocytes treated with 30 micromolar MP before and dur-ing various doses of ionising radiation, with the radiation dose response for untreated cells, indicate a dose reduction factor (DRF) of 2. Similar survival curve experiments using various concentrations of MP, with parallel measurements of uptake of MP into cell nuclei, have en-abled the relationship between drug uptake and extent of radioprotection to be established. Radioprotection has also been demonstrated after systemic administration to mice, for three different endpoints, namely lung, jejunum and bone marrow (survival at 30 days post-TBI). The results of pulse radiolysis studies indicated that the drugs act by reduction of transient radiation-induced oxidative species on DNA. This hypothesis was substantiated by the results of experiments in which MP radioprotection of radiation-induced DNA double-strand breaks, assessed as -H2AX foci, in the human keratinocyte cell line. For both endpoints, the extent of radioprotection increased with MP concentration up to a maximal value. These results are consistent with the hypothesis that radioprotection by MP is mediated by attenuation of the extent of initial DNA damage. However, although MP is a potent radioprotector, it becomes cytotoxic at higher concentrations. This limitation has been addressed in an extensive program of lead optimisation and some promising analogues have emerged from which the next lead will be selected. Given the clinical potential of topical radioprotection, the new analogues are being assessed in terms of delivery to mouse oral mucosa. This is

  14. Fifth international radiopharmaceutical dosimetry symposium

    SciTech Connect

    Watson, E.E.; Schlafke-Stelson, A.T.

    1992-05-01

    This meeting was held to exchange information on how to get better estimates of the radiation absorbed dose. There seems to be a high interest of late in patient dosimetry; discussions were held in the light of revised risk estimates for radiation. Topics included: Strategies of Dose Assessment; Dose Estimation for Radioimmunotherapy; Dose Calculation Techniques and Models; Dose Estimation for Positron Emission Tomography (PET); Kinetics for Dose Estimation; and Small Scale Dosimetry and Microdosimetry. (VC)

  15. Quantitative studies in radiopharmaceutical science

    SciTech Connect

    Cooper, M.; Beck, R.N.

    1989-09-01

    The scientific direction of the work in this grant is unchanged and the 12 research projects in the three major categories represent only minor modification from the proposed work given at site visit. Adjustment was necessary in keeping with the award and to accommodate the resignation of Dr. S. John Gatley who took a position at the Brookhaven National Laboratories. Significant progress is being made in each scientific area with principal responsibility in radiochemistry now assumed by J. Mukherjee and S. Murphy, both of whom have contributed major advances in their areas of fluorination of receptor ligands for studies of the dopaminergic system and approaches to studies of the glutamate type II receptors, respectively. C.T. Chen's work in quantitative method approaches to image integration and analysis continues to receive national and international attention. Similar attention is being given to J. Metz and H. deWit with their work on the effects of drugs of dependency on mood and regional brain metabolism. Resource development in the overall program has been substantial. An equipment grant totaling $350,000 was awarded to the Frank Center for Image Analysis of the FMI by the W.M. Keck Foundation through The University of Chicago/Argonne National Laboratory Center for Imaging Science for purchasing computer systems for graphic display, visualization of 2D and 3D image data, and fast computation. We have purchased nine VAXstations, five DECstations, two SUN/SPARCstations, one AT T Pixel Machine system, and the associated communication links for networking. These systems are currently being installed and tested. This facility will provide added computation capabilities for and facilitate the development of the research projects. 39 refs., 4 figs.

  16. Radiopharmaceuticals for SPECT cancer detection

    NASA Astrophysics Data System (ADS)

    Chernov, V. I.; Medvedeva, A. A.; Zelchan, R. V.; Sinilkin, I. G.; Stasyuk, E. S.; Larionova, L. A.; Slonimskaya, E. M.; Choynzonov, E. L.

    2016-08-01

    The purpose of the study was to assess the efficacy of single photon emission computed tomography (SPECT) with 199Tl and 99mTc-MIBI in the detection of breast, laryngeal and hypopharyngeal cancers. A total of 220 patients were included into the study: 120 patients with breast lesions (100 patients with breast cancer and 20 patients with benign breast tumors) and 100 patients with laryngeal/hypopharyngeal diseases (80 patients with laryngeal/hypopharyngeal cancer and 20 patients with benign laryngeal/hypopharyngeal lesions). No abnormal 199Tl uptake was seen in all patients with benign breast and laryngeal lesions, indicating a 100% specificity of 199Tl SPECT. In the breast cancer patients, the increased 199Tl uptake in the breast was visualized in 94.8% patients, 99mTc-MIBI—in 93.4% patients. The increased 199Tl uptake in axillary lymph nodes was detected in 60% patients, and 99mTc-MIBI—in 93.1% patients. In patients with laryngeal/hypopharyngeal cancer, the sensitivity of SPECT with 199Tl and 99mTc-MIBI was 95%. The 199Tl SPECT sensitivity in identification of regional lymph node metastases in the patients with laryngeal/hypopharyngeal cancer was 75% and the 99mTc-MIBI SPECT sensitivity was 17%. The data obtained showed that SPECT with 199Tl and 99mTc-MIBI can be used as one of the additional imaging methods in detection of tumors.

  17. Radiopharmaceuticals for SPECT Cancer Detection

    NASA Astrophysics Data System (ADS)

    Chernov, V. I.; Medvedeva, A. A.; Zelchan, R. V.; Sinilkin, I. G.; Stasyuk, E. S.; Larionova, L. A.; Slonimskaya, E. M.; Choynzonov, E. L.

    2016-06-01

    The purpose of the study was to assess the efficacy of single photon emission computed tomography (SPECT) with 199Tl and 99mTc-MIBI in the detection of breast, laryngeal and hypopharyngeal cancers. Materials and Methods: a total of 220 patients were included into the study. Of them, there were 120 patients with breast lesions (100 patients with breast cancer and 20 patients with benign breast tumors) and '00 patients with laryngeal/hypopharyngeal diseases (80 patients with laryngeal/hypopharyngeal cancer and 20 patients with benign laryngeal/hypopharyngeal lesions). Results: no abnormal 199Tl uptake was seen in all patients with benign breast and laryngeal lesions, indicating a 100% specificity of 199Tl SPECT. In breast cancer patients, increased 199Tl uptake in the breast was visualized in 94.8% patients, 99mTc-MIBI in 93.4% patients. Increased 199Tl uptake in axillary lymph nodes was detected in 60% patients and 99mTc-MIBI in 93.1% patients. In patients with laryngeal/hypopharyngeal cancer, sensitivity of SPECT with 199Tl and 99mTc-MIBI were 95%. The 199Tl SPECT sensitivity in identification of regional lymph node metastases in patients with laryngeal/hypopharyngeal cancer was 75% and the 99mTc-MIBI SPECT sensitivity was 17%. Conclusion: the data obtained show that SPECT with 199Tl and 99mTc-MIBI can be used as one of the additional imaging methods in detection of tumors.

  18. Methods for Improving Aptamer Binding Affinity.

    PubMed

    Hasegawa, Hijiri; Savory, Nasa; Abe, Koichi; Ikebukuro, Kazunori

    2016-01-01

    Aptamers are single stranded oligonucleotides that bind a wide range of biological targets. Although aptamers can be isolated from pools of random sequence oligonucleotides using affinity-based selection, aptamers with high affinities are not always obtained. Therefore, further refinement of aptamers is required to achieve desired binding affinities. The optimization of primary sequences and stabilization of aptamer conformations are the main approaches to refining the binding properties of aptamers. In particular, sequence optimization using combined in silico sequence recombinations and in vitro functional evaluations is effective for the improvement of binding affinities, however, the binding affinities of aptamers are limited by the low hydrophobicity of nucleic acids. Accordingly, introduction of hydrophobic moieties into aptamers expands the diversity of interactions between aptamers and targets. Moreover, construction of multivalent aptamers by connecting aptamers that recognize distinct epitopes is an attractive approach to substantial increases in binding affinity. In addition, binding affinities can be tuned by optimizing the scaffolds of multivalent constructs. In this review, we summarize the various techniques for improving the binding affinities of aptamers. PMID:27043498

  19. Multiple instance learning of Calmodulin binding sites

    PubMed Central

    Minhas, Fayyaz ul Amir Afsar; Ben-Hur, Asa

    2012-01-01

    Motivation: Calmodulin (CaM) is a ubiquitously conserved protein that acts as a calcium sensor, and interacts with a large number of proteins. Detection of CaM binding proteins and their interaction sites experimentally requires a significant effort, so accurate methods for their prediction are important. Results: We present a novel algorithm (MI-1 SVM) for binding site prediction and evaluate its performance on a set of CaM-binding proteins extracted from the Calmodulin Target Database. Our approach directly models the problem of binding site prediction as a large-margin classification problem, and is able to take into account uncertainty in binding site location. We show that the proposed algorithm performs better than the standard SVM formulation, and illustrate its ability to recover known CaM binding motifs. A highly accurate cascaded classification approach using the proposed binding site prediction method to predict CaM binding proteins in Arabidopsis thaliana is also presented. Availability: Matlab code for training MI-1 SVM and the cascaded classification approach is available on request. Contact: fayyazafsar@gmail.com or asa@cs.colostate.edu PMID:22962461

  20. Backbone Dynamics Of Intracellular Lipid Binding Proteins

    NASA Astrophysics Data System (ADS)

    Gutiérrez-González, Luis H.

    2005-04-01

    The family of intracellular lipid binding proteins (iLBPs) comprises a group of homologous 14-15 kDa proteins that specifically bind and facilitate the transport of fatty acids, bile acids, retinoids or eicosanoids. Members of this family include several types of fatty acid binding proteins (FABPs), ileal lipid binding protein, cellular retinoic acid binding proteins and cellular retinoid binding proteins. As a contribution to understanding the structure-function relationship in this protein family, the solution structure and backbone dynamics of human epidermal-type FABP (E-FABP) determined by NMR spectroscopy are reported. Moreover, hydrogen/deuterium exchange experiments indicated a direct correlation between the stability of the hydrogen-bonding network in the β-sheet structure and the conformational exchange in the millisecond-to-microsecond time range. The features of E-FABP backbone dynamics discussed in the present study are compared with those obtained for other phylogenetically related proteins. A strong interdependence with the overall protein stability and possibly also with the ligand-binding affinity for members of the lipid-binding protein family is shown.

  1. Biodiscovery of aluminum binding peptides

    NASA Astrophysics Data System (ADS)

    Adams, Bryn L.; Sarkes, Deborah A.; Finch, Amethist S.; Hurley, Margaret M.; Stratis-Cullum, Dimitra

    2013-05-01

    Cell surface peptide display systems are large and diverse libraries of peptides (7-15 amino acids) which are presented by a display scaffold hosted by a phage (virus), bacteria, or yeast cell. This allows the selfsustaining peptide libraries to be rapidly screened for high affinity binders to a given target of interest, and those binders quickly identified. Peptide display systems have traditionally been utilized in conjunction with organic-based targets, such as protein toxins or carbon nanotubes. However, this technology has been expanded for use with inorganic targets, such as metals, for biofabrication, hybrid material assembly and corrosion prevention. While most current peptide display systems employ viruses to host the display scaffold, we have recently shown that a bacterial host, Escherichia coli, displaying peptides in the ubiquitous, membrane protein scaffold eCPX can also provide specific peptide binders to an organic target. We have, for the first time, extended the use of this bacterial peptide display system for the biodiscovery of aluminum binding 15mer peptides. We will present the process of biopanning with macroscopic inorganic targets, binder enrichment, and binder isolation and discovery.

  2. Haptenation: Chemical Reactivity and Protein Binding

    PubMed Central

    Chipinda, Itai; Hettick, Justin M.; Siegel, Paul D.

    2011-01-01

    Low molecular weight chemical (LMW) allergens are commonly referred to as haptens. Haptens must complex with proteins to be recognized by the immune system. The majority of occupationally related haptens are reactive, electrophilic chemicals, or are metabolized to reactive metabolites that form covalent bonds with nucleophilic centers on proteins. Nonelectrophilic protein binding may occur through disulfide exchange, coordinate covalent binding onto metal ions on metalloproteins or of metal allergens, themselves, to the major histocompatibility complex. Recent chemical reactivity kinetic studies suggest that the rate of protein binding is a major determinant of allergenic potency; however, electrophilic strength does not seem to predict the ability of a hapten to skew the response between Th1 and Th2. Modern proteomic mass spectrometry methods that allow detailed delineation of potential differences in protein binding sites may be valuable in predicting if a chemical will stimulate an immediate or delayed hypersensitivity. Chemical aspects related to both reactivity and protein-specific binding are discussed. PMID:21785613

  3. Nonphysiological binding of ethylene by plants.

    PubMed

    Abeles, F B

    1984-03-01

    Ethylene binding to seedling tissue of Vicia faba, Phaseolus vulgaris, Glycine max, and Triticum aestivum was demonstrated by determining transit time required for ethylene to move through a glass tube filled with seedling tissue. Transit time for ethylene was greater than that for methane indicating that these tissues had an affinity for ethylene. However, the following observations suggest that the binding was not physiological. Inhibitors of ethylene action such as Ag(+) ions and CO(2) did not decrease binding. Mushrooms which have no known sites of ethylene action also demonstrated ethylene binding. The binding of acetylene, propylene, ethylene, propane, and ethane more closely followed their solubility in water than any known physiological activity. PMID:16663455

  4. Nonphysiological Binding of Ethylene by Plants

    PubMed Central

    Abeles, Fred B.

    1984-01-01

    Ethylene binding to seedling tissue of Vicia faba, Phaseolus vulgaris, Glycine max, and Triticum aestivum was demonstrated by determining transit time required for ethylene to move through a glass tube filled with seedling tissue. Transit time for ethylene was greater than that for methane indicating that these tissues had an affinity for ethylene. However, the following observations suggest that the binding was not physiological. Inhibitors of ethylene action such as Ag+ ions and CO2 did not decrease binding. Mushrooms which have no known sites of ethylene action also demonstrated ethylene binding. The binding of acetylene, propylene, ethylene, propane, and ethane more closely followed their solubility in water than any known physiological activity. PMID:16663455

  5. Ethylene binding site affinity in ripening apples

    SciTech Connect

    Blankenship, S.M. . Dept. of Horticultural Science); Sisler, E.C. )

    1993-09-01

    Scatchard plots for ethylene binding in apples (Malus domestica Borkh.), which were harvested weekly for 5 weeks to include the ethylene climacteric rise, showed C[sub 50] values (concentration of ethylene needed to occupy 50% of the ethylene binding sites) of 0.10, 0.11, 0.34, 0.40, and 0.57 [mu]l ethylene/liter[sup [minus]1], respectively, for each of the 5 weeks. Higher ethylene concentrations were required to saturate the binding sites during the climacteric rise than at other times. Diffusion of [sup 14]C-ethylene from the binding sites was curvilinear and did not show any indication of multiple binding sites. Ethylene was not metabolized by apple tissue.

  6. SU-E-CAMPUS-I-05: Internal Dosimetric Calculations for Several Imaging Radiopharmaceuticals in Preclinical Studies and Quantitative Assessment of the Mouse Size Impact On Them. Realistic Monte Carlo Simulations Based On the 4D-MOBY Model

    SciTech Connect

    Kostou, T; Papadimitroulas, P; Kagadis, GC; Loudos, G

    2014-06-15

    Purpose: Commonly used radiopharmaceuticals were tested to define the most important dosimetric factors in preclinical studies. Dosimetric calculations were applied in two different whole-body mouse models, with varying organ size, so as to determine their impact on absorbed doses and S-values. Organ mass influence was evaluated with computational models and Monte Carlo(MC) simulations. Methods: MC simulations were executed on GATE to determine dose distribution in the 4D digital MOBY mouse phantom. Two mouse models, 28 and 34 g respectively, were constructed based on realistic preclinical exams to calculate the absorbed doses and S-values of five commonly used radionuclides in SPECT/PET studies (18F, 68Ga, 177Lu, 111In and 99mTc).Radionuclide biodistributions were obtained from literature. Realistic statistics (uncertainty lower than 4.5%) were acquired using the standard physical model in Geant4. Comparisons of the dosimetric calculations on the two different phantoms for each radiopharmaceutical are presented. Results: Dose per organ in mGy was calculated for all radiopharmaceuticals. The two models introduced a difference of 0.69% in their brain masses, while the largest differences were observed in the marrow 18.98% and in the thyroid 18.65% masses.Furthermore, S-values of the most important target-organs were calculated for each isotope. Source-organ was selected to be the whole mouse body.Differences on the S-factors were observed in the 6.0–30.0% range. Tables with all the calculations as reference dosimetric data were developed. Conclusion: Accurate dose per organ and the most appropriate S-values are derived for specific preclinical studies. The impact of the mouse model size is rather high (up to 30% for a 17.65% difference in the total mass), and thus accurate definition of the organ mass is a crucial parameter for self-absorbed S values calculation.Our goal is to extent the study for accurate estimations in small animal imaging, whereas it is known

  7. Follitropin receptors contain cryptic ligand binding sites.

    PubMed

    Lin, Win; Bernard, Michael P; Cao, Donghui; Myers, Rebecca V; Kerrigan, John E; Moyle, William R

    2007-01-01

    Human choriogonadotropin (hCG) and follitropin (hFSH) have been shown to contact different regions of the extracellular domains of G-protein coupled lutropin (LHR) and follitropin (FSHR) receptors. We report here that hCG and hFSH analogs interact with different regions of an FSHR/LHR chimera having only two unique LHR residues and that binds both hormones with high affinity. hCG and hFSH analogs dock with this receptor chimera in a manner similar to that in which they bind LHR and FSHR, respectively. This shows that although the FSHR does not normally bind hCG, it contains a cryptic lutropin binding site that has the potential to recognize hCG in a manner similar to the LHR. The presence of this cryptic site may explain why equine lutropins bind many mammalian FSHR and why mutations in the transmembrane domain distant from the extracellular domain enable the FSHR to bind hCG. The leucine-rich repeat domain (LRD) of the FSHR also appears to contain a cryptic FSH binding site that is obscured by other parts of the extracellular domain. This will explain why contacts seen in crystals of hFSH complexed with an LRD fragment of the human FSHR are hard to reconcile with the abilities of FSH analogs to interact with membrane G-protein coupled FSHR. We speculate that cryptic lutropin binding sites in the FSHR, which are also likely to be present in thyrotropin receptors (TSHR), permit the physiological regulation of ligand binding specificity. Cryptic FSH binding sites in the LRD may enable alternate spliced forms of the FSHR to interact with FSH. PMID:17059863

  8. Improving Binding Affinity and Selectivity of Computationally Designed Ligand-Binding Proteins Using Experiments.

    PubMed

    Tinberg, Christine E; Khare, Sagar D

    2016-01-01

    The ability to de novo design proteins that can bind small molecules has wide implications for synthetic biology and medicine. Combining computational protein design with the high-throughput screening of mutagenic libraries of computationally designed proteins is emerging as a general approach for creating binding proteins with programmable binding modes, affinities, and selectivities. The computational step enables the creation of a binding site in a protein that otherwise does not (measurably) bind the intended ligand, and targeted mutagenic screening allows for validation and refinement of the computational model as well as provides orders-of-magnitude increases in the binding affinity. Deep sequencing of mutagenic libraries can provide insights into the mutagenic binding landscape and enable further affinity improvements. Moreover, in such a combined computational-experimental approach where the binding mode is preprogrammed and iteratively refined, selectivity can be achieved (and modulated) by the placement of specified amino acid side chain groups around the ligand in defined orientations. Here, we describe the experimental aspects of a combined computational-experimental approach for designing-using the software suite Rosetta-proteins that bind a small molecule of choice and engineering, using fluorescence-activated cell sorting and high-throughput yeast surface display, high affinity and ligand selectivity. We illustrated the utility of this approach by performing the design of a selective digoxigenin (DIG)-binding protein that, after affinity maturation, binds DIG with picomolar affinity and high selectivity over structurally related steroids. PMID:27094290

  9. Bacterial periplasmic sialic acid-binding proteins exhibit a conserved binding site

    SciTech Connect

    Gangi Setty, Thanuja; Cho, Christine; Govindappa, Sowmya; Apicella, Michael A.; Ramaswamy, S.

    2014-07-01

    Structure–function studies of sialic acid-binding proteins from F. nucleatum, P. multocida, V. cholerae and H. influenzae reveal a conserved network of hydrogen bonds involved in conformational change on ligand binding. Sialic acids are a family of related nine-carbon sugar acids that play important roles in both eukaryotes and prokaryotes. These sialic acids are incorporated/decorated onto lipooligosaccharides as terminal sugars in multiple bacteria to evade the host immune system. Many pathogenic bacteria scavenge sialic acids from their host and use them for molecular mimicry. The first step of this process is the transport of sialic acid to the cytoplasm, which often takes place using a tripartite ATP-independent transport system consisting of a periplasmic binding protein and a membrane transporter. In this paper, the structural characterization of periplasmic binding proteins from the pathogenic bacteria Fusobacterium nucleatum, Pasteurella multocida and Vibrio cholerae and their thermodynamic characterization are reported. The binding affinities of several mutations in the Neu5Ac binding site of the Haemophilus influenzae protein are also reported. The structure and the thermodynamics of the binding of sugars suggest that all of these proteins have a very well conserved binding pocket and similar binding affinities. A significant conformational change occurs when these proteins bind the sugar. While the C1 carboxylate has been identified as the primary binding site, a second conserved hydrogen-bonding network is involved in the initiation and stabilization of the conformational states.

  10. The TRPV5/6 calcium channels contain multiple calmodulin binding sites with differential binding properties.

    PubMed

    Kovalevskaya, Nadezda V; Bokhovchuk, Fedir M; Vuister, Geerten W

    2012-06-01

    The epithelial Ca(2+) channels TRPV5/6 (transient receptor potential vanilloid 5/6) are thoroughly regulated in order to fine-tune the amount of Ca(2+) reabsorption. Calmodulin has been shown to be involved into calcium-dependent inactivation of TRPV5/6 channels by binding directly to the distal C-terminal fragment of the channels (de Groot et al. in Mol Cell Biol 31:2845-2853, 12). Here, we investigate this binding in detail and find significant differences between TRPV5 and TRPV6. We also identify and characterize in vitro four other CaM binding fragments of TRPV5/6, which likely are also involved in TRPV5/6 channel regulation. The five CaM binding sites display diversity in binding modes, binding stoichiometries and binding affinities, which may fine-tune the response of the channels to varying Ca(2+)-concentrations. PMID:22354706

  11. Calmodulin Binding Proteins and Alzheimer's Disease.

    PubMed

    O'Day, Danton H; Eshak, Kristeen; Myre, Michael A

    2015-01-01

    The small, calcium-sensor protein, calmodulin, is ubiquitously expressed and central to cell function in all cell types. Here the literature linking calmodulin to Alzheimer's disease is reviewed. Several experimentally-verified calmodulin-binding proteins are involved in the formation of amyloid-β plaques including amyloid-β protein precursor, β-secretase, presenilin-1, and ADAM10. Many others possess potential calmodulin-binding domains that remain to be verified. Three calmodulin binding proteins are associated with the formation of neurofibrillary tangles: two kinases (CaMKII, CDK5) and one protein phosphatase (PP2B or calcineurin). Many of the genes recently identified by genome wide association studies and other studies encode proteins that contain putative calmodulin-binding domains but only a couple (e.g., APOE, BIN1) have been experimentally confirmed as calmodulin binding proteins. At least two receptors involved in calcium metabolism and linked to Alzheimer's disease (mAchR; NMDAR) have also been identified as calmodulin-binding proteins. In addition to this, many proteins that are involved in other cellular events intimately associated with Alzheimer's disease including calcium channel function, cholesterol metabolism, neuroinflammation, endocytosis, cell cycle events, and apoptosis have been tentatively or experimentally verified as calmodulin binding proteins. The use of calmodulin as a potential biomarker and as a therapeutic target is discussed. PMID:25812852

  12. Human liver aldehyde dehydrogenase: coenzyme binding

    SciTech Connect

    Kosley, L.L.; Pietruszko, R.

    1987-05-01

    The binding of (U-/sup 14/C) NAD to mitochondrial (E2) and cytoplasmin(E1) aldehyde dehydrogenase was measured by gel filtration and sedimentation techniques. The binding data for NAD and (E1) yielded linear Scatchard plots giving a dissociation constant of 25 (+/- 8) uM and the stoichiometry of 2 mol of NAD bound per mol of E1. The binding data for NAD and (E2) gave nonlinear Scatchard plots. The binding of NADH to E2 was measured via fluorescence enhancement; this could not be done with E1 because there was no signal. The dissociation constant for E2 by this technique was 0.7 (+/- 0.4) uM and stoichiometry of 1.0 was obtained. The binding of (U-/sup 14/C) NADH to (E1) and (E2) was also measured by the sedimentation technique. The binding data for (E1) and NADH gave linear Scatchard plots giving a dissociation constant of 13 (+/- 6) uM and the stoichiometry of 2.0. The binding data for NADH to (E2) gave nonlinear Scatchard plots. With (E1), the dissociation constants for both NAD and NADH are similar to those determined kinetically, but the stoichiometry is only half of that found by stopped flow technique. With (E2) the dissociation constant by fluorometric procedure was 2 orders of magnitude less than that from catalytic reaction.

  13. Transcription factor binding energy vs. biological function

    NASA Astrophysics Data System (ADS)

    Djordjevic, M.; Grotewold, E.

    2007-03-01

    Transcription factors (TFs) are proteins that bind to DNA and regulate expression of genes. Identification of transcription factor binding sites within the regulatory segments of genomic DNA is an important step towards understanding of gene regulatory networks. Recent theoretical advances that we developed [1,2], allow us to infer TF-DNA interaction parameters from in-vitro selection experiments [3]. We use more than 6000 binding sequences [3], assembled under controlled conditions, to obtain protein-DNA interaction parameters for a mammalian TF with up to now unprecedented accuracy. Can one accurately identify biologically functional TF binding sites (i.e. the binding sites that regulate gene expression), even with the best possible protein-DNA interaction parameters? To address this issue we i) compare our prediction of protein binding with gene expression data, ii) use evolutionary comparison between related mammalian genomes. Our results strongly suggest that in a genome there exists a large number of randomly occurring high energy binding sites that are not biologically functional. [1] M Djordjevic, submitted to Biomol. Eng. [2] M. Djordjevic and A. M. Sengupta, Phys. Biol. 3: 13, 2006. [3] E. Roulet et al., Nature Biotech. 20: 831, 2002.

  14. DNA Triplexes That Bind Several Cofactor Molecules.

    PubMed

    Vollmer, Sven; Richert, Clemens

    2015-12-14

    Cofactors are critical for energy-consuming processes in the cell. Harnessing such processes for practical applications requires control over the concentration of cofactors. We have recently shown that DNA triplex motifs with a designed binding site can be used to capture and release nucleotides with low micromolar dissociation constants. In order to increase the storage capacity of such triplex motifs, we have explored the limits of ligand binding through designed cavities in the oligopurine tract. Oligonucleotides with up to six non-nucleotide bridges between purines were synthesized and their ability to bind ATP, cAMP or FAD was measured. Triplex motifs with several single-nucleotide binding sites were found to bind purines more tightly than triplexes with one large binding site. The optimized triplex consists of 59 residues and four C3-bridges. It can bind up to four equivalents of ligand with apparent Kd values of 52 µM for ATP, 9 µM for FAD, and 2 µM for cAMP. An immobilized version fuels bioluminescence via release of ATP at body temperature. These results show that motifs for high-density capture, storage and release of energy-rich biomolecules can be constructed from synthetic DNA. PMID:26561335

  15. Copper(II) binding properties of hepcidin.

    PubMed

    Kulprachakarn, Kanokwan; Chen, Yu-Lin; Kong, Xiaole; Arno, Maria C; Hider, Robert C; Srichairatanakool, Somdet; Bansal, Sukhvinder S

    2016-06-01

    Hepcidin is a peptide hormone that regulates the homeostasis of iron metabolism. The N-terminal domain of hepcidin is conserved amongst a range of species and is capable of binding Cu(II) and Ni(II) through the amino terminal copper-nickel binding motif (ATCUN). It has been suggested that the binding of copper to hepcidin may have biological relevance. In this study we have investigated the binding of Cu(II) with model peptides containing the ATCUN motif, fluorescently labelled hepcidin and hepcidin using MALDI-TOF mass spectrometry. As with albumin, it was found that tetrapeptide models of hepcidin possessed a higher affinity for Cu(II) than that of native hepcidin. The log K 1 value of hepcidin for Cu(II) was determined as 7.7. Cu(II) binds to albumin more tightly than hepcidin (log K 1 = 12) and in view of the serum concentration difference of albumin and hepcidin, the bulk of kinetically labile Cu(II) present in blood will be bound to albumin. It is estimated that the concentration of Cu(II)-hepcidin will be less than one femtomolar in normal serum and thus the binding of copper to hepcidin is unlikely to play a role in iron homeostasis. As with albumin, small tri and tetra peptides are poor models for the metal binding properties of hepcidin. PMID:26883683

  16. Binding of perlecan to transthyretin in vitro.

    PubMed Central

    Smeland, S; Kolset, S O; Lyon, M; Norum, K R; Blomhoff, R

    1997-01-01

    Transthyretin is one of two specific proteins involved in the transport of thyroid hormones in plasma; it possesses two binding sites for serum retinol-binding protein. In the present study we demonstrate that transthyretin also interacts in vitro with [35S]sulphate-labelled material from the medium of HepG2 cells. By using the same strategy as for purifying serum retinol-binding protein, [35S]sulphate-labelled medium was specifically eluted from a transthyretin-affinity column. Ion-exchange chromatography showed that the material was highly polyanionic, and its size and alkali susceptibility suggested that it was a proteoglycan. Structural analyses with chondroitinase ABC lyase and nitrous acid revealed that approx. 20% was chondroitin sulphate and 80% heparan sulphate. Immunoprecipitation showed that the [35S]sulphate-labelled material contained perlecan. Further analysis by binding studies revealed specific and saturable binding of 125I-transthyretin to perlecan-enriched Matrigel. Because inhibition of sulphation by treating HepG2 cells with sodium chlorate increased the affinity of the perlecan for transthyretin, and [3H]heparin was not retained by the transthyretin affinity column, the binding is probably mediated by the core protein and is not a protein-glycosaminoglycan interaction. Because perlecan is released from transthyretin in water, the binding might be due to hydrophobic interactions. PMID:9307034

  17. Thermodynamic binding constants for gallium transferrin

    SciTech Connect

    Harris, W.R.; Pecoraro, V.L.

    1983-01-18

    Gallium-67 is widely used as an imaging agent for tumors and inflammatory abscesses. It is well stablished that Ga/sup 3 +/ travels through the circulatory system bound to the serum iron transport protein transferrin and that this protein binding is an essential step in tumor localization. However, there have been conflicting reports on the magnitude of the gallium-transferrin binding constants. Therefore, thermodynamic binding constants for gallium complexation at the two specific metal binding sites of human serum transferrin at pH 7.4 and 5 mM NaHCO/sub 3/ have been determined by UV difference spectroscopy. The conditional constants calculated for 27 mM NaHCO/sub 3/ are log K/sub 1/* = 20.3 and log K/sub 2/* = 19.3. These results are discussed in relation to the thermodynamics of transferrin binding of Fe/sup 3 +/ and to previous reports on gallium binding. The strength of transferrin complexation is also compared to that of a series of low molecular weight ligands by using calculated pM values (pM = -log (Ga(H/sub 2/O)/sub 6/)) to express the effective binding strength at pH 7.4.

  18. Improved flow cytometer measurement of binding assays

    DOEpatents

    Saunders, G.C.

    1984-05-30

    The invention relates to a method of measuring binding assays carried out with different size particles wherein the binding assay sample is run through a flow cytometer without separating the sample from the marking agent. The amount of a binding reactant present in a sample is determined by providing particles with a coating of binder and also a known quantity of smaller particles with a coating of binder reactant. The binding reactant is the same as the binding reactant present in the sample. The smaller particles also contain a fluorescent chemical. The particles are combined with the sample and the binding reaction is allowed to occur for a set length of time followed by combining the smaller particles with the mixture of the particles and the sample produced and allowing the binding reactions to proceed to equilibrium. The fluorescence and light scatter of the combined mixture is then measured as the combined mixture passes through a flow cytometer equipped with a laser to bring about fluorescence, and the number and strength of fluorescent events are compared. A similar method is also provided for determining the amount of antigen present in the sample by providing spheres with an antibody coating and some smaller spheres with an antigen coating. (LEW)

  19. Synthesis and evaluation of Lys¹(α,γ-Folate)Lys³(¹⁷⁷Lu-DOTA)-Bombesin(1-14) as a potential theranostic radiopharmaceutical for breast cancer.

    PubMed

    Aranda-Lara, Liliana; Ferro-Flores, Guillermina; Azorín-Vega, Erika; Ramírez, Flor de María; Jiménez-Mancilla, Nallely; Ocampo-García, Blanca; Santos-Cuevas, Clara; Isaac-Olivé, Keila

    2016-01-01

    The aim of this work was to synthesize Lys(1)(α,γ-Folate)-Lys(3)((177)Lu-DOTA)-Bombesin (1-14) ((177)Lu-Folate-BN), as well as to assess its potential for molecular imaging and targeted radiotherapy of breast tumors expressing folate receptors (FR) and gastrin-releasing peptide receptors (GRPR). Radiation absorbed doses of (177)Lu-Folate-BN (74 MBq, i.v.) estimated in athymic mice with T47D-induced breast tumors (positive to FR and GRPR), showed tumor doses of 23.9±2.1 Gy. T47D-tumors were clearly visible (Micro-SPECT/CT images). (177)Lu-Folate-BN demonstrated properties suitable as a theranostic radiopharmaceutical. PMID:26545016

  20. Study of the production yields of 18F, 11C, 13N and 15O positron emitters from plasma-laser proton sources at ELI-Beamlines for labeling of PET radiopharmaceuticals

    NASA Astrophysics Data System (ADS)

    Amato, Ernesto; Italiano, Antonio; Margarone, Daniele; Pagano, Benedetta; Baldari, Sergio; Korn, Georg

    2016-03-01

    The development of novel compact PET radionuclide production systems is of great interest to promote the diffusion of PET diagnostics, especially in view of the continuous development of microfluidics labeling approaches. We studied the feasibility to produce clinically-relevant amounts of PET isotopes by means of laser-accelerated proton sources such that expected at the ELI-Beamlines facility. 18F, 11C, 13N and 15O production yields were calculated through the TALYS software, by taking into account the broad proton spectra expected. With the hypothesized proton fluencies, clinically-relevant amounts of radionuclides can be obtained, suitable to prepare single doses of 18F-, 11C- and 13N-labeled radiopharmaceuticals exploiting fast and efficient microfluidic labeling systems.

  1. Potential pitfalls in the nuclear medicine imaging: Experimental models to evaluate the effect of natural products on the radiolabeling of blood constituents, bioavailability of radiopharmaceutical and on the survival of Escherichia coli strains submitted to the treatment with stannous ion

    NASA Astrophysics Data System (ADS)

    Soares, Scheila F.; Brito, Lavínia C.; Souza, Deise E.; Bernardo, Luciana C.; Oliveira, Joelma F.; Bernardo-Filho, Mario

    2006-12-01

    Single photon emission computed tomography (SPECT) allows studies of physiological or pathological processes. Red blood cells labeled with technetium-99m ( 99mTc-RBC) are used as a radiopharmaceutical in several evaluations. The radiolabeling efficiency and bioavailability of radiopharmaceuticals can be altered by natural/synthetic drugs and may induce pitfalls in the analysis of the nuclear medicine imaging. The labeling with 99mTc requires a reducing agent and stannous chloride (SnCl 2) is widely utilized. However, SnCl 2 presents a citotoxic and/or genotoxic potential in Escherichia coli ( E. coli) strains. The aim of this work was to evaluate the influence of aqueous extracts of Baccharis genistelloides (BG), Terminalia chebula (TC), Maytenus ilicifolia (MI), Cassia angustifolia (CA) and Equisetum arvense (EA) on (i) radiolabeling of blood constituents, (ii) bioavailability of sodium pertechnetate(Na 99mTcO 4) radiopharmaceutical, (iii) survival of E. coli. In vitro labeling of RBC was performed with blood ( Wistar rats) incubated with each extract, SnCl 2 and Na 99mTcO 4. Plasma (P) and blood cells (BC) were isolated, another aliquots precipitated and soluble (SF) and insoluble (IF) fractions isolated and counted. In the bioavailability of Na 99mTcO 4, Wistar rats were treated (7 days) with aqueous extract or with 0.9%NaCl, the radiopharmaceutical was administered, the animals sacrificed, the organs isolated, weighted and radioactivity counted. To evaluate the effect on the bacterial survival, E. coli was treated with: (a) SnCl 2; (b) 0.9% NaCl; (c) vegetal extract; or (d) SnCl 2 and vegetal extract. Radiolabeling efficiency showed a significantly decrease (ANOVA/Tukey post-test, p<0.05) after treatment with BG, TC, MI and CA extracts. The bioavailability results showed that the uptake of Na 99mTcO 4 was altered significantly (unpaired t-student test, p<0.05) in blood, lungs (CA/TC extracts), bone, heart, ovary (EA /TC), spleen, kidney (TC) , pancreas, thyroid

  2. Lipopolysaccharides of Actinobacillus pleuropneumoniae bind pig hemoglobin.

    PubMed Central

    Bélanger, M; Bégin, C; Jacques, M

    1995-01-01

    A previous study indicated that lipopolysaccharides (LPS) extracted from Actinobacillus pleuropneumoniae bind two low-molecular-mass proteins, of approximately 10 and 11 kDa, present in porcine respiratory tract secretions (M. Bélanger, D. Dubreuil, and M. Jacques, Infect. Immun. 62:868-873, 1994). In the present study, we determined the N-terminal amino acid sequences of these two proteins, which revealed high homology with the alpha and beta chains of pig hemoglobin. Some isolates of A. pleuropneumoniae were able to use hemoglobin from various animal species as well as other heme compounds as sole sources of iron for growth, while other isolates were unable to use them. Immunoelectron microscopy showed binding of pig hemoglobin at the surface of all A. pleuropneumoniae isolates as well as labeling of outer membrane blebs. We observed, using Western blotting (immunoblotting), that the lipid A-core region of LPS of all isolates was binding pig hemoglobin. Furthermore, lipid A obtained after acid hydrolysis of LPS extracted from A. pleuropneumoniae was able to bind pig hemoglobin and this binding was completely abolished by preincubation of lipid A with polymyxin B but was not inhibited by preincubation with glucosamines. Fatty acids constituting the lipid A of A. pleuropneumoniae, namely, dodecanoic acid, tetradecanoic acid, 3-hydroxytetradecanoic acid, hexadecanoic acid, and octadecanoic acid, were also binding pig hemoglobin. Our results indicate that LPS of all A. pleuropneumoniae isolates tested bind pig hemoglobin and that lipid A is involved in this binding. Our results also indicate that some A. pleuropneumoniae isolates are, in addition, able to use hemoglobin for growth. Binding of hemoglobin to LPS might represent an important means by which A. pleuropneumoniae acquires iron in vivo from hemoglobin released from erythrocytes lysed by the action of its hemolysins. PMID:7822035

  3. High Affinity Radiopharmaceuticals Based Upon Lansoprazole for PET Imaging of Aggregated Tau in Alzheimer’s Disease and Progressive Supranuclear Palsy: Synthesis, Preclinical Evaluation, and Lead Selection

    PubMed Central

    2014-01-01

    Abnormally aggregated tau is the hallmark pathology of tauopathy neurodegenerative disorders and is a target for development of both diagnostic tools and therapeutic strategies across the tauopathy disease spectrum. Development of carbon-11- or fluorine-18-labeled radiotracers with appropriate affinity and specificity for tau would allow noninvasive quantification of tau burden using positron emission tomography (PET) imaging. We have synthesized [18F]lansoprazole, [11C]N-methyl lansoprazole, and [18F]N-methyl lansoprazole and identified them as high affinity radiotracers for tau with low to subnanomolar binding affinities. Herein, we report radiosyntheses and extensive preclinical evaluation with the aim of selecting a lead radiotracer for translation into human PET imaging trials. We demonstrate that [18F]N-methyl lansoprazole, on account of the favorable half-life of fluorine-18 and its rapid brain entry in nonhuman primates, favorable kinetics, low white matter binding, and selectivity for binding to tau over amyloid, is the lead compound for progression into clinical trials. PMID:24896980

  4. High affinity radiopharmaceuticals based upon lansoprazole for PET imaging of aggregated tau in Alzheimer's disease and progressive supranuclear palsy: synthesis, preclinical evaluation, and lead selection.

    PubMed

    Fawaz, Maria V; Brooks, Allen F; Rodnick, Melissa E; Carpenter, Garrett M; Shao, Xia; Desmond, Timothy J; Sherman, Phillip; Quesada, Carole A; Hockley, Brian G; Kilbourn, Michael R; Albin, Roger L; Frey, Kirk A; Scott, Peter J H

    2014-08-20

    Abnormally aggregated tau is the hallmark pathology of tauopathy neurodegenerative disorders and is a target for development of both diagnostic tools and therapeutic strategies across the tauopathy disease spectrum. Development of carbon-11- or fluorine-18-labeled radiotracers with appropriate affinity and specificity for tau would allow noninvasive quantification of tau burden using positron emission tomography (PET) imaging. We have synthesized [(18)F]lansoprazole, [(11)C]N-methyl lansoprazole, and [(18)F]N-methyl lansoprazole and identified them as high affinity radiotracers for tau with low to subnanomolar binding affinities. Herein, we report radiosyntheses and extensive preclinical evaluation with the aim of selecting a lead radiotracer for translation into human PET imaging trials. We demonstrate that [(18)F]N-methyl lansoprazole, on account of the favorable half-life of fluorine-18 and its rapid brain entry in nonhuman primates, favorable kinetics, low white matter binding, and selectivity for binding to tau over amyloid, is the lead compound for progression into clinical trials. PMID:24896980

  5. In vitro and in vivo studies of an aqueous extract of Matricaria recutita (German chamomile) on the radiolabeling of blood constituents, on the morphology of red blood cells and on the biodistribution of the radiopharmaceutical sodium pertechnetate

    PubMed Central

    Garcia-Pinto, Angélica B.; Santos-Filho, Sebastião D.; Carvalho, Jorge J.; Pereira, Mário J. S.; Fonseca, Adenilson S.; Bernardo-Filho, Mário

    2013-01-01

    Background: Natural products might alter the labeling of blood constituents with technetium-99m (99mTc) and these results may be correlated with modifications of the shape of the red blood cells (RBC). The biodistribution of radiopharmaceuticals can be also altered. Objective: This investigation aimed to determine biological effects of an aqueous extract of chamomile (CE). Materials and Methods: To study the effect of the CE on the labeling of blood constituents with 99mTc, in vitro and in vivo assays were performed. The effect of the CE on the morphology of RBC was observed under light microscope. The images were acquired, processed, and the perimeter/area ratio of the RBC determined. To analyze the effect of the CE on biodistribution of the sodium pertechnetate (Na99mTcO4) in Wistar rats, these animals were treated or not with a CE. Na99mTcO4 was injected, the rats were sacrificed, the organs were removed, weighted and percentage of radioactivity/gram calculated. Result: In the in vitro experiment, the radioactivity on blood cells compartment and on insoluble fractions of plasma was diminished. The shape and the perimeter/area ratio of the RBC were altered in in vitro assays. An increase of the percentage of radioactivity of Na99mTcO4 was observed in stomach after in vivo treatment. Conclusion: These results could be due to substances of the CE or by the products of the metabolism of this extract in the animal organism. These findings are examples of drug interaction with a radiopharmaceutical, which could lead to misdiagnosis in clinical practice with unexpected consequences. PMID:24143045

  6. α-Enolase binds to RNA.

    PubMed

    Hernández-Pérez, Liliana; Depardón, Francisco; Fernández-Ramírez, Fernando; Sánchez-Trujillo, Alejandra; Bermúdez-Crúz, Rosa María; Dangott, Lawrence; Montañez, Cecilia

    2011-09-01

    To detect proteins binding to CUG triplet repeats, we performed magnetic bead affinity assays and North-Western analysis using a (CUG)(10) ssRNA probe and either nuclear or total extracts from rat L6 myoblasts. We report the isolation and identification by mass spectrometry and immunodetection of α-enolase, as a novel (CUG)n triplet repeat binding protein. To confirm our findings, rat recombinant α-enolase was cloned, expressed and purified; the RNA binding activity was verified by electrophoretic mobility shift assays using radiolabeled RNA probes. Enolase may play other roles in addition to its well described function in glycolysis. PMID:21621582

  7. Muscarine binding sites in bovine adrenal medulla.

    PubMed

    Barron, B A; Murrin, L C; Hexum, T D

    1986-03-18

    The presence of muscarinic binding sites in the bovine adrenal medulla was investigated using [3H]QNB and the bovine adrenal medulla. Scatchard analysis combined with computer analysis yielded data consistent with a two binding site configuration. KDs of 0.15 and 14 nM and Bmax s of 29 and 210 fmol/mg protein, respectively, were observed. Displacement of [3H]QNB by various cholinergic agents is, in order of decreasing potency: QNB, dexetimide, atropine, scopolamine, imipramine, desipramine, oxotremorine, pilocarpine, acetylcholine, methacholine and carbachol. These results demonstrate the presence of more than one muscarine binding site in the bovine adrenal gland. PMID:3709656

  8. Relativistic corrections to the triton binding energy

    SciTech Connect

    Sammarruca, F.; Xu, D.P.; Machleidt, R. )

    1992-11-01

    The influence of relativity on the triton binding energy is investigated. The relativistic three-dimensional version of the Bethe-Salpeter equation proposed by Blankenbecler and Sugar (BbS) is used. Relativistic (nonseparable) one-boson-exchange potentials (constructed in the BbS framework) are employed for the two-nucleon interaction. In a 34-channel Faddeev calculation, it is found that relativistic effects increase the triton binding energy by about 0.2 MeV. Including charge dependence (besides relativity), the final triton binding energy predictions are 8.33 and 8.16 MeV for the Bonn A and B potentials, respectively.

  9. Measuring Binding Affinity of Protein-Ligand Interaction Using Spectrophotometry: Binding of Neutral Red to Riboflavin-Binding Protein

    ERIC Educational Resources Information Center

    Chenprakhon, Pirom; Sucharitakul, Jeerus; Panijpan, Bhinyo; Chaiyen, Pimchai

    2010-01-01

    The dissociation constant, K[subscript d], of the binding of riboflavin-binding protein (RP) with neutral red (NR) can be determined by titrating RP to a fixed concentration of NR. Upon adding RP to the NR solution, the maximum absorption peak of NR shifts to 545 nm from 450 nm for the free NR. The change of the absorption can be used to determine…

  10. Two nucleotide binding sites modulate ( sup 3 H) glyburide binding to rat cortex membranes

    SciTech Connect

    Johnson, D.E.; Gopalakrishnan, M.; Triggle, D.J.; Janis, R.A. State Univ. of New York, Buffalo )

    1991-03-11

    The effects of nucleotides on the binding of the ATP-dependent K{sup +}-channel antagonist ({sup 3}H)glyburide (GLB) to rat cortex membranes were examined. Nucleotide triphosphates (NTPs) and nucleotide diphosphate (NDPs) inhibited the binding of GLB. This effect was dependent on the presence of dithiothreitol (DTT). Inhibition of binding by NTPs, with the exception of ATP{gamma}S, was dependent on the presence of Mg{sup 2+}. GLB binding showed a biphasic response to ADP: up to 3 mM, ADP inhibited binding, and above this concentration GLB binding increased rapidly, and was restored to normal levels by 10 mM ADP. In the presence of Mg{sup 2+}, ADP did not stimulate binding. Saturation analysis in the presence of Mg{sup 2+} and increasing concentrations of ADP showed that ADP results primarily in a change of the B{sub max} for GLB binding. The differential effects of NTPS and NDPs indicate that two nucleotide binding sites regulate GLB binding.

  11. Ligand Binding to Macromolecules: Allosteric and Sequential Models of Cooperativity.

    ERIC Educational Resources Information Center

    Hess, V. L.; Szabo, Attila

    1979-01-01

    A simple model is described for the binding of ligands to macromolecules. The model is applied to the cooperative binding by hemoglobin and aspartate transcarbamylase. The sequential and allosteric models of cooperative binding are considered. (BB)

  12. Structure and Function of Lipopolysaccharide Binding Protein

    NASA Astrophysics Data System (ADS)

    Schumann, Ralf R.; Leong, Steven R.; Flaggs, Gail W.; Gray, Patrick W.; Wright, Samuel D.; Mathison, John C.; Tobias, Peter S.; Ulevitch, Richard J.

    1990-09-01

    The primary structure of lipopolysaccharide binding protein (LBP), a trace plasma protein that binds to the lipid A moiety of bacterial lipopolysaccharides (LPSs), was deduced by sequencing cloned complementary DNA. LBP shares sequence identity with another LPS binding protein found in granulocytes, bactericidal/permeability-increasing protein, and with cholesterol ester transport protein of the plasma. LBP may control the response to LPS under physiologic conditions by forming high-affinity complexes with LPS that bind to monocytes and macrophages, which then secrete tumor necrosis factor. The identification of this pathway for LPS-induced monocyte stimulation may aid in the development of treatments for diseases in which Gram-negative sepsis or endotoxemia are involved.

  13. Human Frataxin: Iron And Ferrochelatase Binding Surface

    SciTech Connect

    Bencze, K.Z.; Yoon, T.; Millan-Pacheco, C.; Bradley, P.B.; Pastor, N.; Cowan, J.A.; Stemmler, T.L.

    2009-06-02

    The coordinated iron structure and ferrochelatase binding surface of human frataxin have been characterized to provide insight into the protein's ability to serve as the iron chaperone during heme biosynthesis.

  14. Lamin-Binding Proteins in Caenorhabditis elegans.

    PubMed

    Dobrzynska, Agnieszka; Askjaer, Peter; Gruenbaum, Yosef

    2016-01-01

    The nuclear lamina, composed of lamins and numerous lamin-associated proteins, is required for mechanical stability, mechanosensing, chromatin organization, developmental gene regulation, mRNA transcription, DNA replication, nuclear assembly, and nuclear positioning. Mutations in lamins or lamin-binding proteins cause at least 18 distinct human diseases that affect specific tissues such as muscle, adipose, bone, nerve, or skin, and range from muscular dystrophies to lipodystrophy, peripheral neuropathy, or accelerated aging. Caenorhabditis elegans has unique advantages in studying lamin-binding proteins. These advantages include the low complexity of genes encoding lamin and lamin-binding proteins, advanced transgenic techniques, simple application of RNA interference, sophisticated genetic strategies, and a large collection of mutant lines. This chapter provides detailed and comprehensive protocols for the genetic and phenotypic analysis of lamin-binding proteins in C. elegans. PMID:26778571

  15. Binding of ATP to the progesterone receptor.

    PubMed Central

    Moudgil, V K; Toft, D O

    1975-01-01

    The possible interaction of progesterone--receptor complexes with nucleotides was tested by affinity chromatography. The cytosol progesterone receptor from hen oviduct was partially purified by ammonium sulfate precipitation before use. When progesterone was bound to the receptor, the resulting complex could be selectively adsorbed onto columns of ATP-Sepharose. This interaction was reversible and of an ionic nature since it could be disrupted by high-salt conditions. A competitive binding assay was used to test the specificity of receptor binding to several other nucleotides, including ADP, AMP, and cAMP. A clear specificity for binding ATP was evident from these studies. When ATP was added to receptor preparations, the nucleotide did not affect the sedimentation properties or hormone binding characteristics of the receptor. Although the function of ATP remains unknown, these studies indicate a role of this nucleotide in some aspect of hormone receptor activity. PMID:165493

  16. Universal binding energy relations in metallic adhesion

    NASA Technical Reports Server (NTRS)

    Ferrante, J.; Smith, J. R.; Rose, J. H.

    1981-01-01

    Scaling relations which map metallic adhesive binding energy onto a single universal binding energy curve are discussed in relation to adhesion, friction, and wear in metals. The scaling involved normalizing the energy to the maximum binding energy and normalizing distances by a suitable combination of Thomas-Fermi screening lengths. The universal curve was found to be accurately represented by E*(A*)= -(1+beta A) exp (-Beta A*) where E* is the normalized binding energy, A* is the normalized separation, and beta is the normalized decay constant. The calculated cohesive energies of potassium, barium, copper, molybdenum, and samarium were also found to scale by similar relations, suggesting that the universal relation may be more general than for the simple free electron metals.

  17. Hardware device binding and mutual authentication

    SciTech Connect

    Hamlet, Jason R; Pierson, Lyndon G

    2014-03-04

    Detection and deterrence of device tampering and subversion by substitution may be achieved by including a cryptographic unit within a computing device for binding multiple hardware devices and mutually authenticating the devices. The cryptographic unit includes a physically unclonable function ("PUF") circuit disposed in or on the hardware device, which generates a binding PUF value. The cryptographic unit uses the binding PUF value during an enrollment phase and subsequent authentication phases. During a subsequent authentication phase, the cryptographic unit uses the binding PUF values of the multiple hardware devices to generate a challenge to send to the other device, and to verify a challenge received from the other device to mutually authenticate the hardware devices.

  18. Exciton Binding Energy of Monolayer WS2

    PubMed Central

    Zhu, Bairen; Chen, Xi; Cui, Xiaodong

    2015-01-01

    The optical properties of monolayer transition metal dichalcogenides (TMDC) feature prominent excitonic natures. Here we report an experimental approach to measuring the exciton binding energy of monolayer WS2 with linear differential transmission spectroscopy and two-photon photoluminescence excitation spectroscopy (TP-PLE). TP-PLE measurements show the exciton binding energy of 0.71 ± 0.01 eV around K valley in the Brillouin zone. PMID:25783023

  19. Bilirubin Binding Capacity in the Preterm Neonate.

    PubMed

    Amin, Sanjiv B

    2016-06-01

    Total serum/plasma bilirubin (TB), the biochemical measure currently used to evaluate and manage hyperbilirubinemia, is not a useful predictor of bilirubin-induced neurotoxicity in premature infants. Altered bilirubin-albumin binding in premature infants limits the usefulness of TB in premature infants. In this article, bilirubin-albumin binding, a modifying factor for bilirubin-induced neurotoxicity, in premature infants is reviewed. PMID:27235205

  20. Molecular design of substrate binding sites

    SciTech Connect

    Shelnutt, J.A.; Hobbs, J.D.

    1991-12-31

    Computer-aided molecular design methods were used to tailor binding sites for small substrate molecules, including CO{sub 2} and methane. The goal is to design a cavity, adjacent to a catalytic metal center, into which the substrate will selectively bind through only non-bonding interactions with the groups lining the binding pocket. Porphyrins are used as a basic molecular structure, with various substituents added to construct the binding pocket. The conformations of these highly-substituted porphyrins are predicted using molecular mechanics calculations with a force field that gives accurate predictions for metalloporhyrins. Dynamics and energy-minimization calculations of substrate molecules bound to the cavity indicate high substrate binding affinity. The size, shape and charge-distribution of groups surrounding the cavity provide molecular selectivity. Specifically, calculated binding energies of methane, benzene, dichloromethane, CO{sub 2} and chloroform vary by about 10 kcal/mol for metal octaethyl-tetraphenylporphyrins (OETPPs) with chloroform, dichloromethane, and CO{sub 2} having the lowest. Significantly, a solvent molecule is found in the cavity in the X-ray structures of Co- and CuOETPP crystals obtained from dichloromethane. 5 refs., 3 figs., 3 tabs.

  1. Molecular design of substrate binding sites

    SciTech Connect

    Shelnutt, J.A.; Hobbs, J.D.

    1991-01-01

    Computer-aided molecular design methods were used to tailor binding sites for small substrate molecules, including CO{sub 2} and methane. The goal is to design a cavity, adjacent to a catalytic metal center, into which the substrate will selectively bind through only non-bonding interactions with the groups lining the binding pocket. Porphyrins are used as a basic molecular structure, with various substituents added to construct the binding pocket. The conformations of these highly-substituted porphyrins are predicted using molecular mechanics calculations with a force field that gives accurate predictions for metalloporhyrins. Dynamics and energy-minimization calculations of substrate molecules bound to the cavity indicate high substrate binding affinity. The size, shape and charge-distribution of groups surrounding the cavity provide molecular selectivity. Specifically, calculated binding energies of methane, benzene, dichloromethane, CO{sub 2} and chloroform vary by about 10 kcal/mol for metal octaethyl-tetraphenylporphyrins (OETPPs) with chloroform, dichloromethane, and CO{sub 2} having the lowest. Significantly, a solvent molecule is found in the cavity in the X-ray structures of Co- and CuOETPP crystals obtained from dichloromethane. 5 refs., 3 figs., 3 tabs.

  2. DNA-aptamers binding aminoglycoside antibiotics.

    PubMed

    Nikolaus, Nadia; Strehlitz, Beate

    2014-01-01

    Aptamers are short, single stranded DNA or RNA oligonucleotides that are able to bind specifically and with high affinity to their non-nucleic acid target molecules. This binding reaction enables their application as biorecognition elements in biosensors and assays. As antibiotic residues pose a problem contributing to the emergence of antibiotic-resistant pathogens and thereby reducing the effectiveness of the drug to fight human infections, we selected aptamers targeted against the aminoglycoside antibiotic kanamycin A with the aim of constructing a robust and functional assay that can be used for water analysis. With this work we show that aptamers that were derived from a Capture-SELEX procedure targeting against kanamycin A also display binding to related aminoglycoside antibiotics. The binding patterns differ among all tested aptamers so that there are highly substance specific aptamers and more group specific aptamers binding to a different variety of aminoglycoside antibiotics. Also the region of the aminoglycoside antibiotics responsible for aptamer binding can be estimated. Affinities of the different aptamers for their target substance, kanamycin A, are measured with different approaches and are in the micromolar range. Finally, the proof of principle of an assay for detection of kanamycin A in a real water sample is given. PMID:24566637

  3. Anion binding to the ubiquitin molecule.

    PubMed Central

    Makhatadze, G. I.; Lopez, M. M.; Richardson, J. M.; Thomas, S. T.

    1998-01-01

    Effects of different salts (NaCl, MgCl2, CaCl2, GdmCl, NaBr, NaClO4, NaH2PO4, Na2SO4) on the stability of the ubiquitin molecule at pH 2.0 have been studied by differential scanning calorimetry, circular dichroism, and Tyr fluorescence spectroscopies. It is shown that all of the salts studied significantly increase the thermostability of the ubiquitin molecule, and that this stabilization can be interpreted in terms of anion binding. Estimated thermodynamic parameters of binding for Cl- show that this binding is relatively weak (Kd = 0.15 M) and is characterized by a negative enthalpy of -15 kJ/mol per site. Particularly surprising was the observed stabilizing effect of GdmCl through the entire concentration range studied (0.01-2 M), however, to a lesser extent than stabilization by NaCl. This stabilizing effect of GdmCl appears to arise from the binding of Cl- ions. Analysis of the observed changes in the stability of the ubiquitin molecule in the presence of GdmCl can be adequately described by combining the thermodynamic model of denaturant binding with Cl- binding effects. PMID:9541401

  4. Theoretical studies of binding of mannose-binding protein to monosaccharides

    NASA Astrophysics Data System (ADS)

    Aida-Hyugaji, Sachiko; Takano, Keiko; Takada, Toshikazu; Hosoya, Haruo; Kojima, Naoya; Mizuochi, Tsuguo; Inoue, Yasushi

    2004-11-01

    Binding properties of mannose-binding protein (MBP) to monosaccharides are discussed based on ab initio molecular orbital calculations for cluster models constructed. The calculated binding energies indicate that MBP has an affinity for N-acetyl- D-glucosamine, D-mannose, L-fucose, and D-glucose rather than D-galactose and N-acetyl- D-galactosamine, which is consistent with the biochemical experimental results. Electrostatic potential surfaces at the binding site of four monosaccharides having binding properties matched well with that of MBP. A vacant frontier orbital was found to be localized around the binding site of MBP, suggesting that MBP-monosaccharide interaction may occur through electrostatic and orbital interactions.

  5. Folding and binding energy of a calmodulin-binding cell antiproliferative peptide.

    PubMed

    Almudallal, Ahmad M; Saika-Voivod, Ivan; Stewart, John M

    2015-09-01

    We carry out a computational study of a calmodulin-binding peptide shown to be effective in reducing cell proliferation. We find several folded states for two short variants of different length of the peptide and determine the location of the binding site on calmodulin, the binding free energy for the different conformers and structural details that play a role in optimal binding. Binding to a hydrophobic pocket in calmodulin occurs via an anchoring phenylalanine residue of the natively disordered peptide, and is enhanced when a neighbouring hydrophobic residue acts as a co-anchor. The shorter sequence possesses better binding to calmodulin, which is encouraging in terms of the development of non-peptide analogues as therapeutic agents. PMID:26310499

  6. Fucose-binding Lotus tetragonolobus lectin binds to human polymorphonuclear leukocytes and induces a chemotactic response.

    PubMed

    VanEpps, D E; Tung, K S

    1977-09-01

    Fucose-binding L. tetragonolobus lectin to the surface of human polymorphonuclear leukocytes (PMN) and induces a chemotactic response. Both surface binding and chemotaxis are inhibited by free fucose but not by fructose, mannose, or galactose. The lectin-binding sites on PMN are unrelated to the A, B, or O blood group antigen. Utilization of this lectin should be a useful tool in isolating PMN membrane components and in analyzing the mechanism of neutrophil chemotaxis. PMID:330752

  7. Leukocyte Protease Binding to Nucleic Acids Promotes Nuclear Localization and Cleavage of Nucleic Acid Binding Proteins

    PubMed Central

    Thomas, Marshall P.; Whangbo, Jennifer; McCrossan, Geoffrey; Deutsch, Aaron; Martinod, Kimberly; Walch, Michael; Lieberman, Judy

    2014-01-01

    Killer lymphocyte granzyme (Gzm) serine proteases induce apoptosis of pathogen-infected cells and tumor cells. Many known Gzm substrates are nucleic acid binding proteins, and the Gzms accumulate in the target cell nucleus by an unknown mechanism. Here we show that human Gzms bind to DNA and RNA with nanomolar affinity. Gzms cleave their substrates most efficiently when both are bound to nucleic acids. RNase treatment of cell lysates reduces Gzm cleavage of RNA binding protein (RBP) targets, while adding RNA to recombinant RBP substrates increases in vitro cleavage. Binding to nucleic acids also influences Gzm trafficking within target cells. Pre-incubation with competitor DNA and DNase treatment both reduce Gzm nuclear localization. The Gzms are closely related to neutrophil proteases, including neutrophil elastase (NE) and cathepsin G (CATG). During neutrophil activation, NE translocates to the nucleus to initiate DNA extrusion into neutrophil extracellular traps (NETs), which bind NE and CATG. These myeloid cell proteases, but not digestive serine proteases, also bind DNA strongly and localize to nuclei and NETs in a DNA-dependent manner. Thus, high affinity nucleic acid binding is a conserved and functionally important property specific to leukocyte serine proteases. Furthermore, nucleic acid binding provides an elegant and simple mechanism to confer specificity of these proteases for cleavage of nucleic acid binding protein substrates that play essential roles in cellular gene expression and cell proliferation. PMID:24771851

  8. Recent improvements to Binding MOAD: a resource for protein-ligand binding affinities and structures.

    PubMed

    Ahmed, Aqeel; Smith, Richard D; Clark, Jordan J; Dunbar, James B; Carlson, Heather A

    2015-01-01

    For over 10 years, Binding MOAD (Mother of All Databases; http://www.BindingMOAD.org) has been one of the largest resources for high-quality protein-ligand complexes and associated binding affinity data. Binding MOAD has grown at the rate of 1994 complexes per year, on average. Currently, it contains 23,269 complexes and 8156 binding affinities. Our annual updates curate the data using a semi-automated literature search of the references cited within the PDB file, and we have recently upgraded our website and added new features and functionalities to better serve Binding MOAD users. In order to eliminate the legacy application server of the old platform and to accommodate new changes, the website has been completely rewritten in the LAMP (Linux, Apache, MySQL and PHP) environment. The improved user interface incorporates current third-party plugins for better visualization of protein and ligand molecules, and it provides features like sorting, filtering and filtered downloads. In addition to the field-based searching, Binding MOAD now can be searched by structural queries based on the ligand. In order to remove redundancy, Binding MOAD records are clustered in different families based on 90% sequence identity. The new Binding MOAD, with the upgraded platform, features and functionalities, is now equipped to better serve its users. PMID:25378330

  9. Crystal Structure of the Botulinum Neurotoxin Type G Binding Domain: Insight into Cell Surface Binding

    SciTech Connect

    Stenmark, Pål; Dong, Min; Dupuy, Jérôme; Chapman, Edwin R.; Stevens, Raymond C.

    2011-11-02

    Botulinum neurotoxins (BoNTs) typically bind the neuronal cell surface via dual interactions with both protein receptors and gangliosides. We present here the 1.9-{angstrom} X-ray structure of the BoNT serotype G (BoNT/G) receptor binding domain (residues 868-1297) and a detailed view of protein receptor and ganglioside binding regions. The ganglioside binding motif (SxWY) has a conserved structure compared to the corresponding regions in BoNT serotype A and BoNT serotype B (BoNT/B), but several features of interactions with the hydrophilic face of the ganglioside are absent at the opposite side of the motif in the BoNT/G ganglioside binding cleft. This may significantly reduce the affinity between BoNT/G and gangliosides. BoNT/G and BoNT/B share the protein receptor synaptotagmin (Syt) I/II. The Syt binding site has a conserved hydrophobic plateau located centrally in the proposed protein receptor binding interface (Tyr1189, Phe1202, Ala1204, Pro1205, and Phe1212). Interestingly, only 5 of 14 residues that are important for binding between Syt-II and BoNT/B are conserved in BoNT/G, suggesting that the means by which BoNT/G and BoNT/B bind Syt diverges more than previously appreciated. Indeed, substitution of Syt-II Phe47 and Phe55 with alanine residues had little effect on the binding of BoNT/G, but strongly reduced the binding of BoNT/B. Furthermore, an extended solvent-exposed hydrophobic loop, located between the Syt binding site and the ganglioside binding cleft, may serve as a third membrane association and binding element to contribute to high-affinity binding to the neuronal membrane. While BoNT/G and BoNT/B are homologous to each other and both utilize Syt-I/Syt-II as their protein receptor, the precise means by which these two toxin serotypes bind to Syt appears surprisingly divergent.

  10. RNA binding protein and binding site useful for expression of recombinant molecules

    DOEpatents

    Mayfield, Stephen

    2000-01-01

    The present invention relates to a gene expression system in eukaryotic and prokaryotic cells, preferably plant cells and intact plants. In particular, the invention relates to an expression system having a RB47 binding site upstream of a translation initiation site for regulation of translation mediated by binding of RB47 protein, a member of the poly(A) binding protein family. Regulation is further effected by RB60, a protein disulfide isomerase. The expression system is capable of functioning in the nuclear/cytoplasm of cells and in the chloroplast of plants. Translation regulation of a desired molecule is enhanced approximately 100 fold over that obtained without RB47 binding site activation.

  11. RNA binding protein and binding site useful for expression of recombinant molecules

    DOEpatents

    Mayfield, Stephen P.

    2006-10-17

    The present invention relates to a gene expression system in eukaryotic and prokaryotic cells, preferably plant cells and intact plants. In particular, the invention relates to an expression system having a RB47 binding site upstream of a translation initiation site for regulation of translation mediated by binding of RB47 protein, a member of the poly(A) binding protein family. Regulation is further effected by RB60, a protein disulfide isomerase. The expression system is capable of functioning in the nuclear/cytoplasm of cells and in the chloroplast of plants. Translation regulation of a desired molecule is enhanced approximately 100 fold over that obtained without RB47 binding site activation.

  12. Radiation inactivation reveals discrete cation binding sites that modulate dihydropyridine binding sites

    SciTech Connect

    Bolger, G.T.; Skolnick, P.; Kempner, E.S. )

    1989-08-01

    In low ionic strength buffer (5 mM Tris.HCl), the binding of (3H) nitrendipine to dihydropyridine calcium antagonist binding sites of mouse forebrain membranes is increased by both Na{sup +} and Ca{sup 2+}. Radiation inactivation was used to determine the target size of ({sup 3}H)nitrendipine binding sites in 5 mM Tris.HCl buffer, in the presence and absence of these cations. After irradiation, ({sup 3}H) nitrendipine binding in buffer with or without Na+ was diminished, due to a loss of binding sites and also to an increase in Kd. After accounting for radiation effects on the dissociation constant, the target size for the nitrendipine binding site in buffer was 160-170 kDa and was 170-180 kDa in the presence of sodium. In the presence of calcium ions, ({sup 3}H)nitrendipine binding showed no radiation effects on Kd and yielded a target size of 150-170 kDa. These findings suggest, as in the case of opioid receptors, the presence of high molecular weight membrane components that modulate cation-induced alterations in radioligand binding to dihydropyridine binding sites.

  13. Folding funnels, binding funnels, and protein function.

    PubMed Central

    Tsai, C. J.; Kumar, S.; Ma, B.; Nussinov, R.

    1999-01-01

    Folding funnels have been the focus of considerable attention during the last few years. These have mostly been discussed in the general context of the theory of protein folding. Here we extend the utility of the concept of folding funnels, relating them to biological mechanisms and function. In particular, here we describe the shape of the funnels in light of protein synthesis and folding; flexibility, conformational diversity, and binding mechanisms; and the associated binding funnels, illustrating the multiple routes and the range of complexed conformers. Specifically, the walls of the folding funnels, their crevices, and bumps are related to the complexity of protein folding, and hence to sequential vs. nonsequential folding. Whereas the former is more frequently observed in eukaryotic proteins, where the rate of protein synthesis is slower, the latter is more frequent in prokaryotes, with faster translation rates. The bottoms of the funnels reflect the extent of the flexibility of the proteins. Rugged floors imply a range of conformational isomers, which may be close on the energy landscape. Rather than undergoing an induced fit binding mechanism, the conformational ensembles around the rugged bottoms argue that the conformers, which are most complementary to the ligand, will bind to it with the equilibrium shifting in their favor. Furthermore, depending on the extent of the ruggedness, or of the smoothness with only a few minima, we may infer nonspecific, broad range vs. specific binding. In particular, folding and binding are similar processes, with similar underlying principles. Hence, the shape of the folding funnel of the monomer enables making reasonable guesses regarding the shape of the corresponding binding funnel. Proteins having a broad range of binding, such as proteolytic enzymes or relatively nonspecific endonucleases, may be expected to have not only rugged floors in their folding funnels, but their binding funnels will also behave similarly

  14. Mannose-binding geometry of pradimicin A.

    PubMed

    Nakagawa, Yu; Doi, Takashi; Taketani, Takara; Takegoshi, K; Igarashi, Yasuhiro; Ito, Yukishige

    2013-08-01

    Pradimicins (PRMs) and benanomicins are the only family of non-peptidic natural products with lectin-like properties, that is, they recognize D-mannopyranoside (Man) in the presence of Ca(2+) ions. Coupled with their unique Man binding ability, they exhibit antifungal and anti-HIV activities through binding to Man-containing glycans of pathogens. Notwithstanding the great potential of PRMs as the lectin mimics and therapeutic leads, their molecular basis of Man recognition has yet to be established. Their aggregate-forming propensity has impeded conventional interaction analysis in solution, and the analytical difficulty is exacerbated by the existence of two Man binding sites in PRMs. In this work, we investigated the geometry of the primary Man binding of PRM-A, an original member of PRMs, by the recently developed analytical strategy using the solid aggregate composed of the 1:1 complex of PRM-A and Man. Evaluation of intermolecular distances by solid-state NMR spectroscopy revealed that the C2-C4 region of Man is in close contact with the primary binding site of PRM-A, while the C1 and C6 positions of Man are relatively distant. The binding geometry was further validated by co-precipitation experiments using deoxy-Man derivatives, leading to the proposal that PRM-A binds not only to terminal Man residues at the non-reducing end of glycans, but also to internal 6-substituted Man residues. The present study provides new insights into the molecular basis of Man recognition and glycan specificity of PRM-A. PMID:23832850

  15. Predicting Ca(2+)-binding sites in proteins.

    PubMed Central

    Nayal, M; Di Cera, E

    1994-01-01

    The coordination shell of Ca2+ ions in proteins contains almost exclusively oxygen atoms supported by an outer shell of carbon atoms. The bond-strength contribution of each ligating oxygen in the inner shell can be evaluated by using an empirical expression successfully applied in the analysis of crystals of metal oxides. The sum of such contributions closely approximates the valence of the bound cation. When a protein is embedded in a very fine grid of points and an algorithm is used to calculate the valence of each point representing a potential Ca(2+)-binding site, a typical distribution of valence values peaked around 0.4 is obtained. In 32 documented Ca(2+)-binding proteins, containing a total of 62 Ca(2+)-binding sites, a very small fraction of points in the distribution has a valence close to that of Ca2+. Only 0.06% of the points have a valence > or = 1.4. These points share the remarkable tendency to cluster around documented Ca2+ ions. A high enough value of the valence is both necessary (58 out of 62 Ca(2+)-binding sites have a valence > or = 1.4) and sufficient (87% of the grid points with a valence > or = 1.4 are within 1.0 A from a documented Ca2+ ion) to predict the location of bound Ca2+ ions. The algorithm can also be used for the analysis of other cations and predicts the location of Mg(2+)- and Na(+)-binding sites in a number of proteins. The valence is, therefore, a tool of pinpoint accuracy for locating cation-binding sites, which can also be exploited in engineering high-affinity binding sites and characterizing the linkage between structural components and functional energetics for molecular recognition of metal ions by proteins. Images Fig. 4 PMID:8290605

  16. Molecular interactions and metal binding in the theophylline-binding core of an RNA aptamer.

    PubMed Central

    Zimmermann, G R; Wick, C L; Shields, T P; Jenison, R D; Pardi, A

    2000-01-01

    An RNA aptamer containing a 15-nt binding site shows high affinity and specificity for the bronchodilator theophylline. A variety of base modifications or 2' deoxyribose substitutions in binding-site residues were tested for theophyllinebinding affinity and the results were compared with the previously determined three-dimensional structure of the RNA-theophylline complex. The RNA-theophylline complex contains a U6-A28-U23 base triple, and disruption of this A28-U23 Hoogsteen-pair by a 7-deaza, 2'-deoxy A28 mutant reduces theophylline binding >45-fold at 25 degrees C. U24 is part of a U-turn in the core of the RNA, and disruption of this U-turn motif by a 2'-deoxy substitution of U24 also reduces theophylline binding by >90-fold. Several mutations outside the "conserved core" of the RNA aptamer showed reduced binding affinity, and these effects could be rationalized by comparison with the three-dimensional structure of the complex. Divalent ions are absolutely required for high-affinity theophylline binding. High-affinity binding was observed with 5 mM Mg2+, Mn2+, or Co2+ ions, whereas little or no significant binding was observed for other divalent or lanthanide ions. A metal-binding site in the core of the complex was revealed by paramagnetic Mn2+-induced broadening of specific RNA resonances in the NMR spectra. When caffeine is added to the aptamer in tenfold excess, the NMR spectra show no evidence for binding in the conserved core and instead the drug stacks on the terminal helix. The lack of interaction between caffeine and the theophylline-binding site emphasizes the extreme molecular discrimination of this RNA aptamer. PMID:10836787

  17. Evidence for chemoreceptors with bimodular ligand-binding regions harboring two signal-binding sites

    PubMed Central

    Pineda-Molina, Estela; Reyes-Darias, José-Antonio; Lacal, Jesús; Ramos, Juan L.; García-Ruiz, Juan Manuel; Gavira, Jose A.; Krell, Tino

    2012-01-01

    Chemoreceptor-based signaling is a central mechanism in bacterial signal transduction. Receptors are classified according to the size of their ligand-binding region. The well-studied cluster I proteins have a 100- to 150-residue ligand-binding region that contains a single site for chemoattractant recognition. Cluster II receptors, which contain a 220- to 300-residue ligand-binding region and which are almost as abundant as cluster I receptors, remain largely uncharacterized. Here, we report high-resolution structures of the ligand-binding region of the cluster II McpS chemotaxis receptor (McpS-LBR) of Pseudomonas putida KT2440 in complex with different chemoattractants. The structure of McpS-LBR represents a small-molecule binding domain composed of two modules, each able to bind different signal molecules. Malate and succinate were found to bind to the membrane-proximal module, whereas acetate binds to the membrane-distal module. A structural alignment of the two modules revealed that the ligand-binding sites could be superimposed and that amino acids involved in ligand recognition are conserved in both binding sites. Ligand binding to both modules was shown to trigger chemotactic responses. Further analysis showed that McpS-like receptors were found in different classes of proteobacteria, indicating that this mode of response to different carbon sources may be universally distributed. The physiological relevance of the McpS architecture may lie in its capacity to respond with high sensitivity to the preferred carbon sources malate and succinate and, at the same time, mediate lower sensitivity responses to the less preferred but very abundant carbon source acetate. PMID:23112148

  18. Promoter-distal RNA polymerase II binding discriminates active from inactive CCAAT/ enhancer-binding protein beta binding sites

    PubMed Central

    Savic, Daniel; Roberts, Brian S.; Carleton, Julia B.; Partridge, E. Christopher; White, Michael A.; Cohen, Barak A.; Cooper, Gregory M.; Gertz, Jason; Myers, Richard M.

    2015-01-01

    Transcription factors (TFs) bind to thousands of DNA sequences in mammalian genomes, but most of these binding events appear to have no direct effect on gene expression. It is unclear why only a subset of TF bound sites are actively involved in transcriptional regulation. Moreover, the key genomic features that accurately discriminate between active and inactive TF binding events remain ambiguous. Recent studies have identified promoter-distal RNA polymerase II (RNAP2) binding at enhancer elements, suggesting that these interactions may serve as a marker for active regulatory sequences. Despite these correlative analyses, a thorough functional validation of these genomic co-occupancies is still lacking. To characterize the gene regulatory activity of DNA sequences underlying promoter-distal TF binding events that co-occur with RNAP2 and TF sites devoid of RNAP2 occupancy using a functional reporter assay, we performed cis-regulatory element sequencing (CRE-seq). We tested more than 1000 promoter-distal CCAAT/enhancer-binding protein beta (CEBPB)-bound sites in HepG2 and K562 cells, and found that CEBPB-bound sites co-occurring with RNAP2 were more likely to exhibit enhancer activity. CEBPB-bound sites further maintained substantial cell-type specificity, indicating that local DNA sequence can accurately convey cell-type–specific regulatory information. By comparing our CRE-seq results to a comprehensive set of genome annotations, we identified a variety of genomic features that are strong predictors of regulatory element activity and cell-type–specific activity. Collectively, our functional assay results indicate that RNAP2 occupancy can be used as a key genomic marker that can distinguish active from inactive TF bound sites. PMID:26486725

  19. Ag(I)-binding to phytochelatins.

    PubMed

    Mehra, R K; Tran, K; Scott, G W; Mulchandani, P; Saini, S S

    1996-02-01

    Phytochelatins (PCs) are glutathione-derived peptides with the general structure (gamma-Glu-Cys)nGly, where n varies from 2 to 11. A variety of metal ions such as Cu(II), Cd(II), Pb(II), Zn(II), and Ag(I) induce PC synthesis in plants and some yeasts. It has generally been assumed that the inducer metals also bind PCs. However, very little information is available on the binding of metals other than Cu(I) and Cd(II) to PCs. In this paper, we describe the Ag(I)-binding characteristics of PCs with the structure (gamma-Glu-Cys)2Gly, (gamma-Glu-Cys)3Gly, and (gamma-Glu-Cys)4Gly. The Ag(I)-binding stoichiometries of these three peptides were determined by (i) UV/VIS spectrophotometry, (ii) luminescence spectroscopy at 77 K, and (iii) reverse-phase HPLC. The three techniques yielded similar results. ApoPCs exhibit featureless absorption in the 220-340 nm range. The binding of Ag(I) to PCs induced the appearance of specific absorption shoulders. The titration end point was indicated by the flattening of the characteristic absorption shoulders. Similarly, luminescence at 77 K due to Ag(I)-thiolate clusters increased with the addition of graded Ag(I) equivalents. The luminescence declined when Ag(I) equivalents in excess of the saturating amounts were added to the peptides. At neutral pH, (gamma-Glu-Cys)2Gly, (gamma-Glu-Cys)3Gly, and (gamma-Glu-Cys)4Gly bind 1.0, 1.5, and 4.0 equivalents of Ag(I), respectively. The Ag(I)-binding capacity of (gamma-Glu-Cys)2Gly and (gamma-Glu-Cys)3Gly was increased at pH 5.0 and below so that Ag(I)/-SH ratio approached 1.0. A similar pH-dependent binding of Ag(I) to glutathione was also observed. The increased Ag(I)-binding to PCs at lower pH is of physiological significance as these peptides accumulate in acidic vacuoles. We also report lifetime data on Ag(I)-PCs. The relatively long decay-times (approximately 0.1-0.3 msec) accompanied with a large Stokes shift in the emission band are indicative of spin-forbidden phosphorescence. PMID

  20. DNA Binding to the Silica Surface.

    PubMed

    Shi, Bobo; Shin, Yun Kyung; Hassanali, Ali A; Singer, Sherwin J

    2015-08-27

    We investigate the DNA-silica binding mechanism using molecular dynamics simulations. This system is of technological importance, and also of interest to explore how negatively charged DNA can bind to a silica surface, which is also negatively charged at pH values above its isoelectric point near pH 3. We find that the two major binding mechanisms are attractive interactions between DNA phosphate and surface silanol groups and hydrophobic bonding between DNA base and silica hydrophobic region. Umbrella sampling and the weighted histogram analysis method (WHAM) are used to calculate the free energy surface for detachment of DNA from a binding configuration to a location far from the silica surface. Several factors explain why single-stranded DNA (ssDNA) has been observed to be more strongly attracted to silica than double-stranded (dsDNA): (1) ssDNA is more flexible and therefore able to maximize the number of binding interactions. (2) ssDNA has free unpaired bases to form hydrophobic attachment to silica while dsDNA has to break hydrogen bonds with base partners to get free bases. (3) The linear charge density of dsDNA is twice that of ssDNA. We devise a procedure to approximate the atomic forces between biomolecules and amorphous silica to enable large-scale biomolecule-silica simulations as reported here. PMID:25966319

  1. Peptide binding at the GLP-1 receptor.

    PubMed

    Mann, R; Nasr, N; Hadden, D; Sinfield, J; Abidi, F; Al-Sabah, S; de Maturana, R López; Treece-Birch, J; Willshaw, A; Donnelly, D

    2007-08-01

    The receptor for GLP-1 [glucagon-like peptide-1-(7-36)-amide] is a member of the 'Family B' of GPCRs (G-protein-coupled receptors) comprising an extracellular N-terminal domain containing six conserved cysteine residues (the N-domain) and a core domain (or J-domain) comprising the seven transmembrane helices and interconnecting loop regions. According to the two-domain model for peptide binding, the N-domain is primarily responsible for providing most of the peptide binding energy, whereas the core domain is responsible for binding the N-terminal region of the peptide agonists and transmitting the signal to the intracellular G-protein. Two interesting differences between the binding properties of two GLP-1 receptor agonists, GLP-1 and EX-4 (exendin-4), can be observed. First, while GLP-1 requires its full length to maintain high affinity, the eight N-terminal residues of EX-4 can be removed with little reduction in affinity. Secondly, EX-4 (but not GLP-1) can bind to the fully isolated N-domain of the receptor with an affinity matching that of the full-length receptor. In order to better understand these differences, we have studied the interaction between combinations of full-length or truncated ligands with full-length or truncated receptors. PMID:17635131

  2. Binding of Dissolved Strontium by Micrococcus luteus

    PubMed Central

    Faison, Brendlyn D.; Cancel, Carmen A.; Lewis, Susan N.; Adler, Howard I.

    1990-01-01

    Resting cells of Micrococcus luteus have been shown to remove strontium (Sr) from dilute aqueous solutions of SrCl2 at pH 7. Loadings of 25 mg of Sr per g of cell dry weight were achieved by cells exposed to a solution containing 50 ppm (mg/liter) of Sr. Sr binding occurred in the absence of nutrients and did not require metabolic activity. Initial binding was quite rapid (<0.5 h), although a slow, spontaneous release of Sr was observed over time. Sr binding was inhibited in the presence of polyvalent cations but not monovalent cations. Ca and Sr were bound preferentially over all other cations tested. Sr-binding activity was localized on the cell envelope and was sensitive to various chemical and physical pretreatments. Bound Sr was displaced by divalent ions or by H+. Other monovalent ions were less effective. Bound Sr was also removed by various chelating agents. It was concluded that Sr binding by M. luteus is a reversible equilibrium process. Both ion exchange mediated by acidic cell surface components and intracellular uptake may be involved in this activity. PMID:16348370

  3. Predicting tissue specific transcription factor binding sites

    PubMed Central

    2013-01-01

    Background Studies of gene regulation often utilize genome-wide predictions of transcription factor (TF) binding sites. Most existing prediction methods are based on sequence information alone, ignoring biological contexts such as developmental stages and tissue types. Experimental methods to study in vivo binding, including ChIP-chip and ChIP-seq, can only study one transcription factor in a single cell type and under a specific condition in each experiment, and therefore cannot scale to determine the full set of regulatory interactions in mammalian transcriptional regulatory networks. Results We developed a new computational approach, PIPES, for predicting tissue-specific TF binding. PIPES integrates in vitro protein binding microarrays (PBMs), sequence conservation and tissue-specific epigenetic (DNase I hypersensitivity) information. We demonstrate that PIPES improves over existing methods on distinguishing between in vivo bound and unbound sequences using ChIP-seq data for 11 mouse TFs. In addition, our predictions are in good agreement with current knowledge of tissue-specific TF regulation. Conclusions We provide a systematic map of computationally predicted tissue-specific binding targets for 284 mouse TFs across 55 tissue/cell types. Such comprehensive resource is useful for researchers studying gene regulation. PMID:24238150

  4. C60 fullerene binding to DNA

    NASA Astrophysics Data System (ADS)

    Alshehri, Mansoor H.; Cox, Barry J.; Hill, James M.

    2014-09-01

    Fullerenes have attracted considerable attention in various areas of science and technology. Owing to their exceptional physical, chemical, and biological properties, they have many applications, particularly in cosmetic and medical products. Using the Lennard-Jones 6-12 potential function and the continuum approximation, which assumes that intermolecular interactions can be approximated by average atomic surface densities, we determine the binding energies of a C60 fullerene with respect to both single-strand and double-strand DNA molecules. We assume that all configurations are in a vacuum and that the C60 fullerene is initially at rest. Double integrals are performed to determine the interaction energy of the system. We find that the C60 fullerene binds to the double-strand DNA molecule, at either the major or minor grooves, with binding energies of -4.7 eV or -2.3 eV, respectively, and that the C60 molecule binds to the single-strand DNA molecule with a binding energy of -1.6 eV. Our results suggest that the C60 molecule is most likely to be linked to the major groove of the dsDNA molecule.

  5. Conformational heterogeneity of the calmodulin binding interface

    PubMed Central

    Shukla, Diwakar; Peck, Ariana; Pande, Vijay S.

    2016-01-01

    Calmodulin (CaM) is a ubiquitous Ca2+ sensor and a crucial signalling hub in many pathways aberrantly activated in disease. However, the mechanistic basis of its ability to bind diverse signalling molecules including G-protein-coupled receptors, ion channels and kinases remains poorly understood. Here we harness the high resolution of molecular dynamics simulations and the analytical power of Markov state models to dissect the molecular underpinnings of CaM binding diversity. Our computational model indicates that in the absence of Ca2+, sub-states in the folded ensemble of CaM's C-terminal domain present chemically and sterically distinct topologies that may facilitate conformational selection. Furthermore, we find that local unfolding is off-pathway for the exchange process relevant for peptide binding, in contrast to prior hypotheses that unfolding might account for binding diversity. Finally, our model predicts a novel binding interface that is well-populated in the Ca2+-bound regime and, thus, a candidate for pharmacological intervention. PMID:27040077

  6. Improved flow cytometer measurement of binding assays

    NASA Astrophysics Data System (ADS)

    Saunders, G. C.

    1984-05-01

    A method of measuring binding assays is carried out with different size particles wherein the binding assay sample is run through a flow cytometer without separating the sample from the marking agent. The amount of a binding reactant present in a sample is determined by providing particles with a coating of binder and also known quantity of smaller particles with a coating of binder reactant. The smaller particles also contain a fluorescent chemical. The particles are combined with the sample and the binding reaction is allowed to occur for a set length of time followed by combining the smaller particles with the mixture of the particles and the sample produced and allowing the binding reactions to proceed to equilibrium. The fluorescence and light scatter of the combined mixture is then measured as the combined mixture passes through a flow cytometer equipped with a laser to bring about fluorescence, and the number of fluorescent events are compared. A similar method is also provided for determining the amount of antigen present in the sample by providing spheres with an antibody coating and some smaller spheres with an antigen coating.

  7. Stretching DNA to quantify nonspecific protein binding

    NASA Astrophysics Data System (ADS)

    Goyal, Sachin; Fountain, Chandler; Dunlap, David; Family, Fereydoon; Finzi, Laura

    2012-07-01

    Nonspecific binding of regulatory proteins to DNA can be an important mechanism for target search and storage. This seems to be the case for the lambda repressor protein (CI), which maintains lysogeny after infection of E. coli. CI binds specifically at two distant regions along the viral genome and induces the formation of a repressive DNA loop. However, single-molecule imaging as well as thermodynamic and kinetic measurements of CI-mediated looping show that CI also binds to DNA nonspecifically and that this mode of binding may play an important role in maintaining lysogeny. This paper presents a robust phenomenological approach using a recently developed method based on the partition function, which allows calculation of the number of proteins bound nonspecific to DNA from measurements of the DNA extension as a function of applied force. This approach was used to analyze several cycles of extension and relaxation of λ DNA performed at several CI concentrations to measure the dissociation constant for nonspecific binding of CI (˜100 nM), and to obtain a measurement of the induced DNA compaction (˜10%) by CI.

  8. Binding of dissolved strontium by Micrococcus luteus

    SciTech Connect

    Faison, B.D.; Cancel, C.A.; Lewis, S.N.; Adler, H.I. )

    1990-12-01

    Resting cells of Micrococcus luteus have been shown to remove strontium (Sr) from dilute aqueous solutions of SrCl{sub 2} at pH 7. Loadings of 25 mg of Sr per g of cell dry weight were achieved by cells exposed to a solution containing 50 ppm (mg/liter) of Sr. Sr binding occurred in the absence of nutrients and did not require metabolic activity. Initial binding was quite rapid (<0.5 h), although a slow, spontaneous release of Sr was observed over time. Sr binding was inhibited in the presence of polyvalent cations but not monovalent cations. Ca and Sr were bound preferentially over all other cations tested. Sr-binding activity was localized on the cell envelope and was sensitive to various chemical and physical pretreatments. Bound Sr was displaced by divalent ions or by H{sup +}. Other monovalent ions were less effective. Bound Sr was also removed by various chelating agents. It was concluded that Sr binding by M. luteus is a reversible equilibrium process. Both ion exchange mediated by acidic cell surface components and intracellular uptake may be involved in this activity.

  9. Aminoglycoside binding to Oxytricha Nova Telomeric DNA

    PubMed Central

    Ranjan, Nihar; Andreasen, Katrine F.; Kumar, Sunil; Hyde-volpe, David; Arya, Dev P.

    2012-01-01

    Telomeric DNA sequences have been at the center stage of drug design for cancer treatment in recent years. The ability of these DNA structures to form four stranded nucleic acid structures, called G-quadruplexes, has been perceived as target for inhibiting telomerase activity vital for the longevity of cancer cells. Being highly diverse in structural forms, these G-quadruplexes are subjects of detailed studies of ligand–DNA interactions of different classes, which will pave the way for logical design of more potent ligands in future. The binding of aminoglycosides were investigated with Oxytricha Nova quadruplex forming DNA sequence (GGGGTTTTGGGG)2. Isothermal Titration calorimetry (ITC) determined ligand to quadruplex binding ratio shows 1:1 neomycin:quadruplex binding with association constants (Ka ) ~ 105M−1 while paromomycin was found to have a two-fold weaker affinity than neomycin. The CD titration experiments with neomycin resulted in minimal changes in the CD signal. FID assays, performed to determine the minimum concentration required to displace half of the fluorescent probe bound, showed neomycin as the best of the all aminoglycosides studied for quadruplex binding. Initial NMR footprint suggests that ligand-DNA interactions occur in the wide groove of the quadruplex. Computational docking studies also indicate that aminoglycosides bind in the wide groove of the quadruplex. PMID:20886815

  10. Conformational heterogeneity of the calmodulin binding interface

    NASA Astrophysics Data System (ADS)

    Shukla, Diwakar; Peck, Ariana; Pande, Vijay S.

    2016-04-01

    Calmodulin (CaM) is a ubiquitous Ca2+ sensor and a crucial signalling hub in many pathways aberrantly activated in disease. However, the mechanistic basis of its ability to bind diverse signalling molecules including G-protein-coupled receptors, ion channels and kinases remains poorly understood. Here we harness the high resolution of molecular dynamics simulations and the analytical power of Markov state models to dissect the molecular underpinnings of CaM binding diversity. Our computational model indicates that in the absence of Ca2+, sub-states in the folded ensemble of CaM's C-terminal domain present chemically and sterically distinct topologies that may facilitate conformational selection. Furthermore, we find that local unfolding is off-pathway for the exchange process relevant for peptide binding, in contrast to prior hypotheses that unfolding might account for binding diversity. Finally, our model predicts a novel binding interface that is well-populated in the Ca2+-bound regime and, thus, a candidate for pharmacological intervention.

  11. Binding dynamics and energetic insight into the molecular forces driving nucleotide binding by guanylate kinase.

    PubMed

    Kandeel, Mahmoud; Kitade, Yukio

    2011-01-01

    Plasmodium deoxyguanylate pathways are an attractive area of investigation for future metabolic and drug discovery studies due to their unique substrate specificities. We investigated the energetic contribution to guanylate kinase substrate binding and the forces underlying ligand recognition. In the range from 20 to 35°C, the thermodynamic profiles displayed marked decrease in binding enthalpy, while the free energy of binding showed little changes. GMP produced a large binding heat capacity change of -356 cal mol(-1) K(-1), indicating considerable conformational changes upon ligand binding. Interestingly, the calculated ΔCp was -32 cal mol(-1) K(-1), indicating that the accessible surface area is not the central change in substrate binding, and that other entropic forces, including conformational changes, are more predominant. The thermodynamic signature for GMP is inconsistent with rigid-body association, while dGMP showed more or less rigid-body association. These binding profiles explain the poor catalytic efficiency and low affinity for dGMP compared with GMP. At low temperature, the ligands bind to the receptor site under the effect of hydrophobic forces. Interestingly, by increasing the temperature, the entropic forces gradually vanish and proceed to a nonfavorable contribution, and the interaction occurs mainly through bonding, electrostatic forces, and van der Waals interactions. PMID:21360614

  12. Ancestral Protein Reconstruction Yields Insights into Adaptive Evolution of Binding Specificity in Solute-Binding Proteins.

    PubMed

    Clifton, Ben E; Jackson, Colin J

    2016-02-18

    The promiscuous functions of proteins are an important reservoir of functional novelty in protein evolution, but the molecular basis for binding promiscuity remains elusive. We used ancestral protein reconstruction to experimentally characterize evolutionary intermediates in the functional expansion of the polar amino acid-binding protein family, which has evolved to bind a variety of amino acids with high affinity and specificity. High-resolution crystal structures of an ancestral arginine-binding protein in complex with l-arginine and l-glutamine show that the promiscuous binding of l-glutamine is enabled by multi-scale conformational plasticity, water-mediated interactions, and selection of an alternative conformational substate productive for l-glutamine binding. Evolution of specialized glutamine-binding proteins from this ancestral protein was achieved by displacement of water molecules from the protein-ligand interface, reducing the entropic penalty associated with the promiscuous interaction. These results provide a structural and thermodynamic basis for the co-option of a promiscuous interaction in the evolution of binding specificity. PMID:26853627

  13. Quantification of Cooperativity in Heterodimer-DNA Binding Improves the Accuracy of Binding Specificity Models.

    PubMed

    Isakova, Alina; Berset, Yves; Hatzimanikatis, Vassily; Deplancke, Bart

    2016-05-01

    Many transcription factors (TFs) have the ability to cooperate on DNA elements as heterodimers. Despite the significance of TF heterodimerization for gene regulation, a quantitative understanding of cooperativity between various TF dimer partners and its impact on heterodimer DNA binding specificity models is still lacking. Here, we used a novel integrative approach, combining microfluidics-steered measurements of dimer-DNA assembly with mechanistic modeling of the implicated protein-protein-DNA interactions to quantitatively interrogate the cooperative DNA binding behavior of the adipogenic peroxisome proliferator-activated receptor γ (PPARγ):retinoid X receptor α (RXRα) heterodimer. Using the high throughput MITOMI (mechanically induced trapping of molecular interactions) platform, we derived equilibrium DNA binding data for PPARγ, RXRα, as well as the PPARγ:RXRα heterodimer to more than 300 target DNA sites and variants thereof. We then quantified cooperativity underlying heterodimer-DNA binding and derived an integrative heterodimer DNA binding constant. Using this cooperativity-inclusive constant, we were able to build a heterodimer-DNA binding specificity model that has superior predictive power than the one based on a regular one-site equilibrium. Our data further revealed that individual nucleotide substitutions within the target site affect the extent of cooperativity in PPARγ:RXRα-DNA binding. Our study therefore emphasizes the importance of assessing cooperativity when generating DNA binding specificity models for heterodimers. PMID:26912662

  14. Binding of the Ah receptor to receptor binding factors in chromatin.

    PubMed

    Dunn, R T; Ruh, T S; Ruh, M F

    1993-03-01

    Dioxin induces biological responses through interaction with a specific intracellular receptor, the Ah receptor, and the subsequent interaction of the Ah receptor with chromatin. We report the binding of the Ah receptor, partially purified from rabbit liver, to receptor binding factors in chromatin. Rabbit liver chromatin proteins (CP) were isolated by adsorption of chromatin to hydroxylapatite followed by sequential extraction with 1-8 M GdnHCl. To assay for receptor binding a portion of each CP fraction was reconstituted to rabbit double-stranded DNA using a reverse gradient dialysis of 7.5 to 0 M GdnHCl. These reconstituted nucleoacidic proteins were then examined for binding to [3H]-2,3,7,8-tetrachlorodibenzo-p-dioxin ([3H]TCDD)-receptor complexes by the streptomycin filter assay. Prior to the binding assay, [3H]TCDD-receptor complexes were partially purified by step elution from DEAE-cellulose columns. CP fractions 2, 5, and 7 were found to bind to the Ah receptor with high affinity. Scatchard analysis yielded Kd values in the nanomolar range. Competition with 2-fold excess unlabeled TCDD-receptor complexes was demonstrated, and binding was reduced markedly when the receptor was prepared in the presence of 10 mM molybdate. Such chromatin receptor binding factors (RBFs) may participate in the interaction of receptor with specific DNA sequences resulting in modulation of specific gene expression. PMID:8384852

  15. Selective polyamine-binding proteins. Spermine binding by an androgen-sensitive phosphoprotein.

    PubMed

    Liang, T; Mezzetti, G; Chen, C; Liao, S

    1978-09-01

    Rat ventral prostate contains an acidic protein which can bind spermine selectively. The relative binding affinities of various aliphatic amines for the protein are, in decreasing order, spermine greater than thermine greater than greater than putrecine greater than 1,10-diaminodecane, cadaverine and 1,12-diaminododecane. The binding protein has an isoelectric point at pH 4.3 and a sedimentation coefficient of 3 S. Its molecular weight is approx. 30 000. Histones and nuclear chromatin preparations of the prostate can interact with the binding protein. The spermine-binding activity of the purified prostate protein can be inactivated by treatment with intestinal alkaline phosphatases. The phosphatase treated preparation can then be reactivated by beef heart protein kinase in the presence of cyclic AMP and ATP. The spermine-binding activity of the prostate cytosol protein fraction decreases after castration, but increases very rapidly after the castrated rats are injected with 5alpha-dihydrotestosterone. This finding raises the possibility that, in the postate, certain androgen actions may be dependent on the androgen-induced increase in the acidic protein binding of polyamines and their translocation to a functional cellular site such as nuclear chromatin. In the prostate cytosol, spermine also binds to 4-S tRNAs and to a unique RNA which has a sedimentation coefficient of 1.5 S. PMID:28786

  16. Characterization of DNA Binding and Retinoic Acid Binding Properties of Retinoic Acid Receptor

    NASA Astrophysics Data System (ADS)

    Yang, Na; Schule, Roland; Mangelsdorf, David J.; Evans, Ronald M.

    1991-05-01

    High-level expression of the full-length human retinoic acid receptor (RAR) α and the DNA binding domain of the RAR in Escherichia coli was achieved by using a T7 RNA polymerase-directed expression system. After induction, full-length RAR protein was produced at an estimated level of 20% of the total bacterial proteins. Both intact RAR molecules and the DNA binding domain bind to the cognate DNA response element with high specificity in the absence of retinoic acid. However, this binding is enhanced to a great extent upon the addition of eukaryotic cell extracts. The factor responsible for this enhancement is heat-sensitive and forms a complex with RAR that binds to DNA and exhibits a distinct migration pattern in the gel-mobility-shift assay. The interaction site of the factor with RAR is localized in the 70-amino acid DNA binding region of RAR. The hormone binding ability of the RARα protein was assayed by a charcoal absorption assay and the RAR protein was found to bind to retinoic acid with a K_d of 2.1 x 10-10 M.

  17. Quantification of Cooperativity in Heterodimer-DNA Binding Improves the Accuracy of Binding Specificity Models*

    PubMed Central

    Isakova, Alina; Berset, Yves; Hatzimanikatis, Vassily; Deplancke, Bart

    2016-01-01

    Many transcription factors (TFs) have the ability to cooperate on DNA elements as heterodimers. Despite the significance of TF heterodimerization for gene regulation, a quantitative understanding of cooperativity between various TF dimer partners and its impact on heterodimer DNA binding specificity models is still lacking. Here, we used a novel integrative approach, combining microfluidics-steered measurements of dimer-DNA assembly with mechanistic modeling of the implicated protein-protein-DNA interactions to quantitatively interrogate the cooperative DNA binding behavior of the adipogenic peroxisome proliferator-activated receptor γ (PPARγ):retinoid X receptor α (RXRα) heterodimer. Using the high throughput MITOMI (mechanically induced trapping of molecular interactions) platform, we derived equilibrium DNA binding data for PPARγ, RXRα, as well as the PPARγ:RXRα heterodimer to more than 300 target DNA sites and variants thereof. We then quantified cooperativity underlying heterodimer-DNA binding and derived an integrative heterodimer DNA binding constant. Using this cooperativity-inclusive constant, we were able to build a heterodimer-DNA binding specificity model that has superior predictive power than the one based on a regular one-site equilibrium. Our data further revealed that individual nucleotide substitutions within the target site affect the extent of cooperativity in PPARγ:RXRα-DNA binding. Our study therefore emphasizes the importance of assessing cooperativity when generating DNA binding specificity models for heterodimers. PMID:26912662

  18. Natural ligand binding and transfer from liver fatty acid binding protein (LFABP) to membranes.

    PubMed

    De Gerónimo, Eduardo; Hagan, Robert M; Wilton, David C; Córsico, Betina

    2010-09-01

    Liver fatty acid-binding protein (LFABP) is distinctive among fatty acid-binding proteins because it binds more than one molecule of long-chain fatty acid and a variety of diverse ligands. Also, the transfer of fluorescent fatty acid analogues to model membranes under physiological ionic strength follows a different mechanism compared to most of the members of this family of intracellular lipid binding proteins. Tryptophan insertion mutants sensitive to ligand binding have allowed us to directly measure the binding affinity, ligand partitioning and transfer to model membranes of natural ligands. Binding of fatty acids shows a cooperative mechanism, while acyl-CoAs binding presents a hyperbolic behavior. Saturated fatty acids seem to have a stronger partition to protein vs. membranes, compared to unsaturated fatty acids. Natural ligand transfer rates are more than 200-fold higher compared to fluorescently-labeled analogues. Interestingly, oleoyl-CoA presents a markedly different transfer behavior compared to the rest of the ligands tested, probably indicating the possibility of specific targeting of ligands to different metabolic fates. PMID:20541621

  19. Estrophilin immunoreactivity versus estrogen receptor binding activity in meningiomas: evidence for multiple estrogen binding sites

    SciTech Connect

    Lesch, K.P.; Schott, W.; Gross, S.

    1987-09-01

    The existence of estrogen receptors in human meningiomas has long been a controversial issue. This may be explained, in part, by apparent heterogeneity of estrogen binding sites in meningioma tissue. In this study, estrogen receptors were determined in 58 meningiomas with an enzyme immunoassay using monoclonal antibodies against human estrogen receptor protein (estrophilin) and with a sensitive radioligand binding assay using /sup 125/I-labeled estradiol (/sup 125/I-estradiol) as radioligand. Low levels of estrophilin immunoreactivity were found in tumors from 62% of patients, whereas radioligand binding activity was demonstrated in about 46% of the meningiomas examined. In eight (14%) tissue samples multiple binding sites for estradiol were observed. The immunoreactive binding sites correspond to the classical, high affinity estrogen receptors: the Kd for /sup 125/I-estradiol binding to the receptor was approximately 0.2 nM and the binding was specific for estrogens. The second, low affinity class of binding sites considerably influenced measurement of the classical receptor even at low ligand concentrations. The epidemiological and clinical data from patients with meningiomas, and the existence of specific estrogen receptors confirmed by immunochemical detection, may be important factors in a theory of oncogenesis.

  20. Opioid binding sites in the guinea pig and rat kidney: Radioligand homogenate binding and autoradiography

    SciTech Connect

    Dissanayake, V.U.; Hughes, J.; Hunter, J.C. )

    1991-07-01

    The specific binding of the selective {mu}-, {delta}-, and {kappa}-opioid ligands (3H)(D-Ala2,MePhe4,Gly-ol5)enkephalin ((3H) DAGOL), (3H)(D-Pen2,D-Pen5)enkephalin ((3H)DPDPE), and (3H)U69593, respectively, to crude membranes of the guinea pig and rat whole kidney, kidney cortex, and kidney medulla was investigated. In addition, the distribution of specific 3H-opioid binding sites in the guinea pig and rat kidney was visualized by autoradiography. Homogenate binding and autoradiography demonstrated the absence of {mu}- and {kappa}-opioid binding sites in the guinea pig kidney. No opioid binding sites were demonstrable in the rat kidney. In the guinea pig whole kidney, cortex, and medulla, saturation studies demonstrated that (3H)DPDPE bound with high affinity (KD = 2.6-3.5 nM) to an apparently homogeneous population of binding sites (Bmax = 8.4-30 fmol/mg of protein). Competition studies using several opioid compounds confirmed the nature of the {delta}-opioid binding site. Autoradiography experiments demonstrated that specific (3H)DPDPE binding sites were distributed radially in regions of the inner and outer medulla and at the corticomedullary junction of the guinea pig kidney. Computer-assisted image analysis of saturation data yielded KD values (4.5-5.0 nM) that were in good agreement with those obtained from the homogenate binding studies. Further investigation of the {delta}-opioid binding site in medulla homogenates, using agonist ((3H)DPDPE) and antagonist ((3H)diprenorphine) binding in the presence of Na+, Mg2+, and nucleotides, suggested that the {delta}-opioid site is linked to a second messenger system via a GTP-binding protein. Further studies are required to establish the precise localization of the {delta} binding site in the guinea pig kidney and to determine the nature of the second messenger linked to the GTP-binding protein in the medulla.

  1. Presence of a highly efficient binding to bacterial contamination can distort data from binding studies

    SciTech Connect

    Balcar, V.J. )

    1990-12-01

    {sup 3}HGABA at low concentrations (5-10 nM) was bound by what appeared to be a GABA receptor binding site in bacterial contamination originating from a batch of distilled water. Under experimental conditions similar to those usually employed in {sup 3}HGABA binding studies, the apparent binding displayed a very high specific component and a high efficiency in terms of {sup 3}HGABA bound per mg of protein. The binding was blocked by muscimol but not by isoguvacine, SR95531 and nipecotic acid. These characteristics suggest that the presence of such spurious binding in the experiments using 3H-labeled ligands in brain homogenates may not always be very obvious and, moreover, it can result in subtle, but serious, distortions of data from such studies, which may not be immediately recognized.

  2. The receptor binding domain of botulinum neurotoxin serotype C binds phosphoinositides.

    PubMed

    Zhang, Yanfeng; Varnum, Susan M

    2012-03-01

    Botulinum neurotoxins (BoNTs) are the most toxic proteins known for humans and animals with an extremely low LD(50) of ∼1 ng/kg. BoNTs generally require a protein and a ganglioside on the cell membrane surface for binding, which is known as a "dual receptor" mechanism for host intoxication. Recent studies have suggested that in addition to gangliosides, other membrane lipids such as phosphoinositides may be involved in the interactions with the receptor binding domain (HCR) of BoNTs for better membrane penetration. Using two independent lipid-binding assays, we tested the interactions of BoNT/C-HCR with lipids in vitro domain. BoNT/C-HCR was found to bind negatively charged phospholipids, preferentially phosphoinositides in both assays. Interactions with phosphoinositides may facilitate tighter binding between neuronal membranes and BoNT/C. PMID:22120109

  3. DNA Origami Seesaws as Comparative Binding Assay.

    PubMed

    Nickels, Philipp C; Høiberg, Hans C; Simmel, Stephanie S; Holzmeister, Phil; Tinnefeld, Philip; Liedl, Tim

    2016-06-16

    The application of commonly used force spectroscopy in biological systems is often limited by the need for an invasive tether connecting the molecules of interest to a bead or cantilever tip. Here we present a DNA origami-based prototype in a comparative binding assay. It has the advantage of in situ readout without any physical connection to the macroscopic world. The seesaw-like structure has a lever that is able to move freely relative to its base. Binding partners on each side force the structure into discrete and distinguishable conformations. Model experiments with competing DNA hybridisation reactions yielded a drastic shift towards the conformation with the stronger binding interaction. With reference DNA duplexes of tuneable length on one side, this device can be used to measure ligand interactions in comparative assays. PMID:27038073

  4. Conformation-controlled binding kinetics of antibodies

    NASA Astrophysics Data System (ADS)

    Galanti, Marta; Fanelli, Duccio; Piazza, Francesco

    2016-01-01

    Antibodies are large, extremely flexible molecules, whose internal dynamics is certainly key to their astounding ability to bind antigens of all sizes, from small hormones to giant viruses. In this paper, we build a shape-based coarse-grained model of IgG molecules and show that it can be used to generate 3D conformations in agreement with single-molecule Cryo-Electron Tomography data. Furthermore, we elaborate a theoretical model that can be solved exactly to compute the binding rate constant of a small antigen to an IgG in a prescribed 3D conformation. Our model shows that the antigen binding process is tightly related to the internal dynamics of the IgG. Our findings pave the way for further investigation of the subtle connection between the dynamics and the function of large, flexible multi-valent molecular machines.

  5. Druggability of methyl-lysine binding sites.

    PubMed

    Santiago, C; Nguyen, K; Schapira, M

    2011-12-01

    Structural modules that specifically recognize--or read--methylated or acetylated lysine residues on histone peptides are important components of chromatin-mediated signaling and epigenetic regulation of gene expression. Deregulation of epigenetic mechanisms is associated with disease conditions, and antagonists of acetyl-lysine binding bromodomains are efficacious in animal models of cancer and inflammation, but little is known regarding the druggability of methyl-lysine binding modules. We conducted a systematic structural analysis of readers of methyl marks and derived a predictive druggability landscape of methyl-lysine binding modules. We show that these target classes are generally less druggable than bromodomains, but that some proteins stand as notable exceptions. PMID:22146969

  6. Conformation-controlled binding kinetics of antibodies.

    PubMed

    Galanti, Marta; Fanelli, Duccio; Piazza, Francesco

    2016-01-01

    Antibodies are large, extremely flexible molecules, whose internal dynamics is certainly key to their astounding ability to bind antigens of all sizes, from small hormones to giant viruses. In this paper, we build a shape-based coarse-grained model of IgG molecules and show that it can be used to generate 3D conformations in agreement with single-molecule Cryo-Electron Tomography data. Furthermore, we elaborate a theoretical model that can be solved exactly to compute the binding rate constant of a small antigen to an IgG in a prescribed 3D conformation. Our model shows that the antigen binding process is tightly related to the internal dynamics of the IgG. Our findings pave the way for further investigation of the subtle connection between the dynamics and the function of large, flexible multi-valent molecular machines. PMID:26755272

  7. Mercury-binding proteins of Mytilus edulis

    SciTech Connect

    Roesijadi, G.; Morris, J.E.; Calabrese, A.

    1981-11-01

    Mytilus edulis possesses low molecular weight, mercury-binding proteins. The predominant protein isolated from gill tissue is enriched in cysteinyl residues (8%) and possesses an amino acid composition similar to cadmium-binding proteins of mussels and oysters. Continuous exposure of mussels to 5 ..mu..g/l mercury results in spillover of mercury from these proteins to high molecular weight proteins. Antibodies to these proteins have been isolated, and development of immunoassays is presently underway. Preliminary studies to determine whether exposure of adult mussels to mercury will result in induction of mercury-binding proteins in offspring suggest that such proteins occur in larvae although additional studies are indicated for a conclusive demonstration.

  8. Binding kinetics of lock and key colloids.

    PubMed

    Colón-Meléndez, Laura; Beltran-Villegas, Daniel J; van Anders, Greg; Liu, Jun; Spellings, Matthew; Sacanna, Stefano; Pine, David J; Glotzer, Sharon C; Larson, Ronald G; Solomon, Michael J

    2015-05-01

    Using confocal microscopy and first passage time analysis, we measure and predict the rates of formation and breakage of polymer-depletion-induced bonds between lock-and-key colloidal particles and find that an indirect route to bond formation is accessed at a rate comparable to that of the direct formation of these bonds. In the indirect route, the pocket of the lock particle is accessed by nonspecific bonding of the key particle with the lock surface, followed by surface diffusion leading to specific binding in the pocket of the lock. The surprisingly high rate of indirect binding is facilitated by its high entropy relative to that of the pocket. Rate constants for forward and reverse transitions among free, nonspecific, and specific bonds are reported, compared to theoretical values, and used to determine the free energy difference between the nonspecific and specific binding states. PMID:25956122

  9. Binding in short-term visual memory.

    PubMed

    Wheeler, Mary E; Treisman, Anne M

    2002-03-01

    The integration of complex information in working memory, and its effect on capacity, shape the limits of conscious cognition. The literature conflicts on whether short-term visual memory represents information as integrated objects. A change-detection paradigm using objects defined by color with location or shape was used to investigate binding in short-term visual memory. Results showed that features from the same dimension compete for capacity, whereas features from different dimensions can be stored in parallel. Binding between these features can occur, but focused attention is required to create and maintain the binding over time, and this integrated format is vulnerable to interference. In the proposed model, working memory capacity is limited both by the independent capacity of simple feature stores and by demands on attention networks that integrate this distributed information into complex but unified thought objects. PMID:11900102

  10. Binding of calcium and carbonate to polyacrylates.

    PubMed

    Tribello, Gareth A; Liew, CheeChin; Parrinello, Michele

    2009-05-21

    Polyacrylate molecules can be used to slow the growth of calcium carbonate. However, little is known about the mechanism by which the molecules impede the growth rate. A recent computational study (Bulo et al. Macromolecules 2007, 40, 3437) used metadynamics to investigate the binding of calcium to polyacrylate chains and has thrown some light on the coiling and precipitation of these polymers. We extend these simulations to examine the binding of calcium and carbonate to polyacrylate chains. We show that calcium complexed with both carbonate and polyacrylate is a very stable species. The free energies of calcium-carbonate-polyacrylate complexes, with different polymer configurations, are calculated, and differences in the free energy of the binding of carbonate are shown to be due to differences in the amount of steric hindrance about the calcium, which prevents the approach of the carbonate ion. PMID:19400592

  11. Flow cytometer measurement of binding assays

    DOEpatents

    Saunders, George C.

    1987-01-01

    A method of measuring the result of a binding assay that does not require separation of fluorescent smaller particles is disclosed. In a competitive binding assay the smaller fluorescent particles coated with antigen compete with antigen in the sample being analyzed for available binding sites on larger particles. In a sandwich assay, the smaller, fluorescent spheres coated with antibody attach themselves to molecules containing antigen that are attached to larger spheres coated with the same antibody. The separation of unattached, fluorescent smaller particles is made unnecessary by only counting the fluorescent events triggered by the laser of a flow cytometer when the event is caused by a particle with a light scatter measurement within a certain range corresponding to the presence of larger particles.

  12. Conformation-controlled binding kinetics of antibodies

    PubMed Central

    Galanti, Marta; Fanelli, Duccio; Piazza, Francesco

    2016-01-01

    Antibodies are large, extremely flexible molecules, whose internal dynamics is certainly key to their astounding ability to bind antigens of all sizes, from small hormones to giant viruses. In this paper, we build a shape-based coarse-grained model of IgG molecules and show that it can be used to generate 3D conformations in agreement with single-molecule Cryo-Electron Tomography data. Furthermore, we elaborate a theoretical model that can be solved exactly to compute the binding rate constant of a small antigen to an IgG in a prescribed 3D conformation. Our model shows that the antigen binding process is tightly related to the internal dynamics of the IgG. Our findings pave the way for further investigation of the subtle connection between the dynamics and the function of large, flexible multi-valent molecular machines. PMID:26755272

  13. How Trp repressor binds to its operator.

    PubMed Central

    Staacke, D; Walter, B; Kisters-Woike, B; von Wilcken-Bergmann, B; Müller-Hill, B

    1990-01-01

    We propose that the generally accepted model of a single Trp repressor dimer binding to a center of symmetry in the natural trp operator (Otwinowski et al., 1988) is wrong. We show here that the Trp repressor binds to a sequence whose center is located four base pairs either to the right or to the left of the central axis of symmetry that was previously identified. We show that: (i) the oligonucleotide used by Otwinowski et al. is not retarded by the Trp repressor in a mobility shift assay under conditions wherein a shorter oligonucleotide carrying our consensus sequence is retarded, (ii) that methylation protection experiments on the full natural operator sequence and the short oligonucleotide protect similar patterns and (iii) that by varying every base in the shorter oligonucleotide, we can demonstrate an optimal sequence for Trp repressor binding. Images Fig. 3. Fig. 4. PMID:2189726

  14. [Water binding of adsorptive immobilized lipases].

    PubMed

    Loose, S; Meusel, D; Muschter, A; Ruthe, B

    1990-01-01

    It is supposed that not only the total water content of lipase preparations but more their state of water binding is of technological importance in enzymatic interesterification reactions in systems nearly free from water. The isotherms at 65 degrees C of two microbial lipases immobilized on various adsorbents as well as different adsorbents themselves are shown. The water binding capacity in the range of water content of technological interest decreases from the anion exchange resin Amberlyst A 21 via nonpolar adsorbent Amberlite XAD-2 to kieselguhr Celite 545. It is demonstrated that water binding by lipases is depending on temperature but is also affected by adsorptive immobilization. Adsorptive immobilized lipases show hysteresis, which is very important for preparing a definite water content of the enzyme preparations. PMID:2325750

  15. Calcium binding in pigmented and albino eyes.

    PubMed Central

    Dräger, U C

    1985-01-01

    The localization of calcium binding sites in eyes was determined autoradiographically after extracting endogenous Ca from tissue sections and replacing it with 45Ca. The strongest labeling was associated with pigmented tissues due to the high concentration of melanin, which was shown to bind Ca effectively and in a pH-dependent fashion. The second strongest binding was over the tapetum lucidum of the cat eye, and moderate labeling was associated with eye muscles and epithelium and endothelium of the cornea. The neural retina was generally more lightly labeled than the surrounding tissue of the eye; here the plexiform layers stood out in comparison to the nuclear layers, as did a band located internal to the photoreceptor outer segments. The possibility that the Ca buffering capacity of melanin may represent the common denominator for the various neurological defects found in hypopigmentation mutants is discussed. Images PMID:3863122

  16. BINOCh: binding inference from nucleosome occupancy changes

    PubMed Central

    Meyer, Clifford A.; He, Housheng H.; Brown, Myles; Liu, X. Shirley

    2011-01-01

    Summary: Transcription factor binding events are frequently associated with a pattern of nucleosome occupancy changes in which nucleosomes flanking the binding site increase in occupancy, while those in the vicinity of the binding site itself are displaced. Genome-wide information on enhancer proximal nucleosome occupancy can be readily acquired using ChIP-seq targeting enhancer-related histone modifications such as H3K4me2. Here, we present a software package, BINOCh that allows biologists to use such data to infer the identity of key transcription factors that regulate the response of a cell to a stimulus or determine a program of differentiation. Availability: The BINOCh open source Python package is freely available at http://liulab.dfci.harvard.edu/BINOCh under the FreeBSD license. Contact: cliff@jimmy.harvard.edu; xsliu@jimmy.harvard.edu Supplementary information: Supplementary data are available at Bioinformatics online. PMID:21551136

  17. Mucin Binding Reduces Colistin Antimicrobial Activity

    PubMed Central

    Huang, Johnny X.; Blaskovich, Mark A. T.; Pelingon, Ruby; Ramu, Soumya; Kavanagh, Angela; Elliott, Alysha G.; Butler, Mark S.

    2015-01-01

    Colistin has found increasing use in treating drug-resistant bacterial lung infections, but potential interactions with pulmonary biomolecules have not been investigated. We postulated that colistin, like aminoglycoside antibiotics, may bind to secretory mucin in sputum or epithelial mucin that lines airways, reducing free drug levels. To test this hypothesis, we measured binding of colistin and other antibiotics to porcine mucin, a family of densely glycosylated proteins used as a surrogate for human sputum and airway mucin. Antibiotics were incubated in dialysis tubing with or without mucin, and concentrations of unbound antibiotics able to penetrate the dialysis tubing were measured over time using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The percentage of antibiotic measured in the dialysate after 4 h in the presence of mucin, relative to the amount without mucin, was 15% for colistin, 16% for polymyxin B, 19% for tobramycin, 52% for ciprofloxacin, and 78% for daptomycin. Antibiotics with the strongest mucin binding had an overall polybasic positive charge, whereas those with comparatively little binding were less basic. When comparing MICs measured with or without added mucin, colistin and polymyxin B showed >100-fold increases in MICs for multiple Gram-negative bacteria. Preclinical evaluation of mucin binding should become a standard procedure when considering the potential pulmonary use of new or existing antibiotics, particularly those with a polybasic overall charge. In the airways, mucin binding may reduce the antibacterial efficacy of inhaled or intravenously administered colistin, and the presence of sub-MIC effective antibiotic concentrations could result in the development of antibiotic resistance. PMID:26169405

  18. Oxygen binding by single crystals of hemoglobin.

    PubMed

    Rivetti, C; Mozzarelli, A; Rossi, G L; Henry, E R; Eaton, W A

    1993-03-23

    Reversible oxygen binding curves for single crystals of hemoglobin in the T quaternary structure have been measured using microspectrophotometry. Saturations were determined from complete visible spectra measured with light linearly polarized parallel to the a and c crystal axes. Striking differences were observed between the binding properties of hemoglobin in the crystal and those of hemoglobin in solution. Oxygen binding to the crystal is effectively noncooperative, the Bohr effect is absent, and there is no effect of chloride ion. Also, the oxygen affinity is lower than that of the T quaternary structure in solution. The absence of the Bohr effect supports Perutz's hypothesis on the key role of the salt bridges, which are known from X-ray crystallography to remain intact upon oxygenation. The low affinity and absence of the Bohr effect can be explained by a generalization of the MWC-PSK model (Monod, Wyman, & Changeux, 1965; Perutz, 1970; Szabo & Karplus, 1972) in which both high- and low-affinity tertiary conformations, with broken and unbroken salt bridges, respectively, are populated in the T quaternary structure. Because the alpha and beta hemes make different projections onto the two crystal axes, separate binding curves for the alpha and beta subunits could be calculated from the two measured binding curves. The approximately 5-fold difference between the oxygen affinities of the alpha and beta subunits is much smaller than that predicted from the crystallographic study of Dodson, Liddington, and co-workers, which suggested that oxygen binds only to the alpha hemes.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8457555

  19. Astaxanthin binding protein in Atlantic salmon.

    PubMed

    Matthews, Sarah J; Ross, Neil W; Lall, Santosh P; Gill, Tom A

    2006-06-01

    The rubicund pigmentation in salmon and trout flesh is unique and is due to the deposition of dietary carotenoids, astaxanthin and canthaxanthin in the muscle. The present study was undertaken to determine which protein was responsible for pigment binding. Salmon muscle proteins were solubilized by sequential extractions with non-denaturing, low ionic strength aqueous solutions and segregated as such into six different fractions. Approximately 91% of the salmon myofibrillar proteins were solubilized under non-denaturing conditions using a protocol modified from a method described by Krishnamurthy et al. [Krishnamurthy, G., Chang, H.S., Hultin, H.O., Feng, Y., Srinivasan, S., Kelleher. S.D., 1996. Solubility of chicken breast muscle proteins in solutions of low ionic strength. J. Agric. Food Chem. 44: 408-415.] for the dissolution of avian muscle. To our knowledge, this is the first time this solubilization approach has been applied to the study of molecular interactions in myofibrillar proteins. Astaxanthin binding in each fraction was determined using an in vitro binding assay. In addition, SDS-PAGE and quantitative densitometry were used to separate and determine the relative amounts of each of the proteins in the six fractions. The results showed that alpha-actinin was the only myofibrillar protein correlating significantly (P<0.05) with astaxanthin binding. Alpha-actinin was positively identified using electrophoretic techniques and confirmed by tandem mass spectroscopy. Purified salmon alpha-actinin bound synthetic astaxanthin in a molar ratio of 1.11:1.00. The study was repeated using halibut alpha-actinin, which was found to have a molar binding ratio of astaxanthin to alpha-actinin of 0.893:1. These results suggest that the difference in pigmentation between white fish and Atlantic salmon is not due to binding capacity in the muscle, but rather differences in the metabolism or transport of pigment. PMID:16644255

  20. Lipid binding capacity of spider hemocyanin.

    PubMed

    Cunningham, M; Gómez, C; Pollero, R

    1999-09-01

    The spider hemocyanin capacity to bind different lipid classes was evaluated by measuring some binding kinetic parameters. A very high lipoprotein (VHDL) which contains hemocyanin, was isolated from Polybetes pythagoricus hemolymph plasma and delipidated. Hemocyanin was bound separately to labelled palmitic acid, phosphatidylcholine, cholesterol, and triolein resulting in several artificial lipoprotein structures. It was possible to corroborate in vitro the lipid-hemocyanin interactions which had been previously observed and, consequently, the apolipoprotein role played by the respiratory pigment of spiders. Lipoproteins were analysed by gel filtration chromatography, and three subfractions with different hemocyanin structures were obtained. The four lipid classes were only bound to the hexameric structure (420 Kda), possibly to low polarity sites. Upon radioactivity measurements of the protein-associated lipids, maximal binding ratios (Mr), dissociation constants (Kd), and the maximal binding effectiveness at low lipid concentrations (Eo) were calculated. Lipid/protein ratios were increased proportionally to each available lipid concentration, following a hyperbolic binding model. Values of saturation, affinity, and maximal binding efficiency to hemocyanin were found to be different for each lipid class assayed. The highest lipid/protein ratio (41.5) was obtained with the free fatty acid and the lowest (7.2) with triolein. Phosphatidylcholine and cholesterol showed the highest relative affinities for hemocyanin (Kd = 63 x 10(-5) M and 74 x 10(-5) M, respectively). Phosphatidylcholine at low concentrations, similar to the physiological ones, presented the highest Eo value. Maximal lipid/protein ratios reached in vitro, were greater than those in P. pythagoricus VHDL, pointing out that hemocyanin could play the apolipoprotein role even under physiological conditions with a very high plasma lipid concentration. J. Exp. Zool. 284:368-373, 1999. PMID:10451413

  1. Dendrimers bind antioxidant polyphenols and cisplatin drug.

    PubMed

    Abderrezak, Amine; Bourassa, Philippe; Mandeville, Jean-Sebastian; Sedaghat-Herati, Reza; Tajmir-Riahi, Heidar-Ali

    2012-01-01

    Synthetic polymers of a specific shape and size play major role in drug delivery systems. Dendrimers are unique synthetic macromolecules of nanometer dimensions with a highly branched structure and globular shape with potential applications in gene and drug delivery. We examine the interaction of several dendrimers of different compositions mPEG-PAMAM (G3), mPEG-PAMAM (G4) and PAMAM (G4) with hydrophilic and hydrophobic drugs cisplatin, resveratrol, genistein and curcumin at physiological conditions. FTIR and UV-visible spectroscopic methods as well as molecular modeling were used to analyse drug binding mode, the binding constant and the effects of drug complexation on dendrimer stability and conformation. Structural analysis showed that cisplatin binds dendrimers in hydrophilic mode via Pt cation and polymer terminal NH(2) groups, while curcumin, genistein and resveratrol are located mainly in the cavities binding through both hydrophobic and hydrophilic contacts. The overall binding constants of durg-dendrimers are ranging from 10(2) M(-1) to 10(3) M(-1). The affinity of dendrimer binding was PAMAM-G4>mPEG-PAMAM-G4>mPEG-PAMAM-G3, while the order of drug-polymer stability was curcumin>cisplatin>genistein>resveratrol. Molecular modeling showed larger stability for genisten-PAMAM-G4 (ΔG = -4.75 kcal/mol) than curcumin-PAMAM-G4 ((ΔG = -4.53 kcal/mol) and resveratrol-PAMAM-G4 ((ΔG = -4.39 kcal/mol). Dendrimers might act as carriers to transport hydrophobic and hydrophilic drugs. PMID:22427960

  2. Salt modulates the stability and lipid binding affinity of the adipocyte lipid-binding proteins

    NASA Technical Reports Server (NTRS)

    Schoeffler, Allyn J.; Ruiz, Carmen R.; Joubert, Allison M.; Yang, Xuemei; LiCata, Vince J.

    2003-01-01

    Adipocyte lipid-binding protein (ALBP or aP2) is an intracellular fatty acid-binding protein that is found in adipocytes and macrophages and binds a large variety of intracellular lipids with high affinity. Although intracellular lipids are frequently charged, biochemical studies of lipid-binding proteins and their interactions often focus most heavily on the hydrophobic aspects of these proteins and their interactions. In this study, we have characterized the effects of KCl on the stability and lipid binding properties of ALBP. We find that added salt dramatically stabilizes ALBP, increasing its Delta G of unfolding by 3-5 kcal/mol. At 37 degrees C salt can more than double the stability of the protein. At the same time, salt inhibits the binding of the fluorescent lipid 1-anilinonaphthalene-8-sulfonate (ANS) to the protein and induces direct displacement of the lipid from the protein. Thermodynamic linkage analysis of the salt inhibition of ANS binding shows a nearly 1:1 reciprocal linkage: i.e. one ion is released from ALBP when ANS binds, and vice versa. Kinetic experiments show that salt reduces the rate of association between ANS and ALBP while simultaneously increasing the dissociation rate of ANS from the protein. We depict and discuss the thermodynamic linkages among stability, lipid binding, and salt effects for ALBP, including the use of these linkages to calculate the affinity of ANS for the denatured state of ALBP and its dependence on salt concentration. We also discuss the potential molecular origins and potential intracellular consequences of the demonstrated salt linkages to stability and lipid binding in ALBP.

  3. Estradiol Binds to Insulin and Insulin Receptor Decreasing Insulin Binding in vitro

    PubMed Central

    Root-Bernstein, Robert; Podufaly, Abigail; Dillon, Patrick F.

    2014-01-01

    Rationale: Insulin (INS) resistance associated with hyperestrogenemias occurs in gestational diabetes mellitus, polycystic ovary syndrome, ovarian hyperstimulation syndrome, estrogen therapies, metabolic syndrome, and obesity. The mechanism by which INS and estrogen interact is unknown. We hypothesize that estrogen binds directly to INS and the insulin receptor (IR) producing INS resistance. Objectives: To determine the binding constants of steroid hormones to INS, the IR, and INS-like peptides derived from the IR; and to investigate the effect of estrogens on the binding of INS to its receptor. Methods: Ultraviolet spectroscopy, capillary electrophoresis, and NMR demonstrated estrogen binding to INS and its receptor. Horse-radish peroxidase-linked INS was used in an ELISA-like procedure to measure the effect of estradiol on binding of INS to its receptor. Measurements: Binding constants for estrogens to INS and the IR were determined by concentration-dependent spectral shifts. The effect of estradiol on INS binding to its receptor was determined by shifts in the INS binding curve. Main Results: Estradiol bound to INS with a Kd of 12 × 10−9 M and to the IR with a Kd of 24 × 10−9 M, while other hormones had significantly less affinity. Twenty-two nanomolars of estradiol shifted the binding curve of INS to its receptor 0.8 log units to the right. Conclusion: Estradiol concentrations in hyperestrogenemic syndromes may interfere with INS binding to its receptor producing significant INS resistance. PMID:25101056

  4. Structural stabilization of GTP-binding domains in circularly permuted GTPases: Implications for RNA binding

    PubMed Central

    Anand, Baskaran; Verma, Sunil Kumar; Prakash, Balaji

    2006-01-01

    GTP hydrolysis by GTPases requires crucial residues embedded in a conserved G-domain as sequence motifs G1–G5. However, in some of the recently identified GTPases, the motif order is circularly permuted. All possible circular permutations were identified after artificially permuting the classical GTPases and subjecting them to profile Hidden Markov Model searches. This revealed G4–G5–G1–G2–G3 as the only possible circular permutation that can exist in nature. It was also possible to recognize a structural rationale for the absence of other permutations, which either destabilize the invariant GTPase fold or disrupt regions that provide critical residues for GTP binding and hydrolysis, such as Switch-I and Switch-II. The circular permutation relocates Switch-II to the C-terminus and leaves it unfastened, thus affecting GTP binding and hydrolysis. Stabilizing this region would require the presence of an additional domain following Switch-II. Circularly permuted GTPases (cpGTPases) conform to such a requirement and always possess an ‘anchoring’ C-terminal domain. There are four sub-families of cpGTPases, of which three possess an additional domain N-terminal to the G-domain. The biochemical function of these domains, based on available experimental reports and domain recognition analysis carried out here, are suggestive of RNA binding. The features that dictate RNA binding are unique to each subfamily. It is possible that RNA-binding modulates GTP binding or vice versa. In addition, phylogenetic analysis indicates a closer evolutionary relationship between cpGTPases and a set of universally conserved bacterial GTPases that bind the ribosome. It appears that cpGTPases are RNA-binding proteins possessing a means to relate GTP binding to RNA binding. PMID:16648363

  5. Free-radical-mediated DNA binding.

    PubMed Central

    O'Brien, P J

    1985-01-01

    Free-radical metabolites can be generated metabolically by a one-electron reductase-catalyzed reaction or a "peroxidase" catalyzed oxidation or by photoactivation of a wide variety of aromatic xenobiotics. Radicals may also be generated during lipid peroxidation. Some radicals can react with DNA or bind covalently or noncovalently as a dismutation product or as a dimer, trimer or polymeric product. Modification to the DNA can result in single-strand breaks, loss of template activity, and crosslinking. The binding can prevent enzymic digestion. In some cases, the radicals react with oxygen, resulting before conversion to DNA reactive oxygen species. Most radicals probably do not interact with DNA. PMID:3007090

  6. Ice-Binding Proteins and Their Function.

    PubMed

    Bar Dolev, Maya; Braslavsky, Ido; Davies, Peter L

    2016-06-01

    Ice-binding proteins (IBPs) are a diverse class of proteins that assist organism survival in the presence of ice in cold climates. They have different origins in many organisms, including bacteria, fungi, algae, diatoms, plants, insects, and fish. This review covers the gamut of IBP structures and functions and the common features they use to bind ice. We discuss mechanisms by which IBPs adsorb to ice and interfere with its growth, evidence for their irreversible association with ice, and methods for enhancing the activity of IBPs. The applications of IBPs in the food industry, in cryopreservation, and in other technologies are vast, and we chart out some possibilities. PMID:27145844

  7. Binding energies of hypernuclei and hypernuclear interactions

    SciTech Connect

    Bodmer, A.R. |; Murali, S.; Usmani, Q.N.

    1996-05-01

    In part 1 the effect of nuclear core dynamics on the binding energies of {Lambda} hypernuclei is discussed in the framework of variational correlated wave functions. In particular, the authors discuss a new rearrangement energy contribution and its effect on the core polarization. In part 2 they consider the interpretation of the {Lambda} single-particle energy in terms of basic {Lambda}-nuclear interactions using a local density approximation based on a Fermi hypernetted chain calculation of the A binding to nuclear matter. To account for the data strongly repulsive 3-body {Lambda}NN forces are required. Also in this framework they discuss core polarization for medium and heavier hypernuclei.

  8. Binding of actin to lens alpha crystallins

    NASA Technical Reports Server (NTRS)

    Gopalakrishnan, S.; Takemoto, L.; Spooner, B. S. (Principal Investigator)

    1992-01-01

    Actin has been coupled to a cyanogen bromide-activated Sepharose 4B column, then tested for binding to alpha, beta, and gamma crystallin preparations from the bovine lens. Alpha, but not beta or gamma, crystallins bound to the actin affinity column in a time dependent and saturable manner. Subfractionation of the alpha crystallin preparation into the alpha-A and alpha-B species, followed by incubation with the affinity column, demonstrated that both species bound approximately the same. Together, these studies demonstrate a specific and saturable binding of lens alpha-A and alpha-B with actin.

  9. Partial characterization of a proacrosin binding protein.

    PubMed

    Yi, L S; Runion, C M; Willand, J L; Polakoski, K L

    1992-01-01

    All of the acid (pH 4.0) extracted proacrosin from porcine epididymal spermatozoa was found to be tightly associated with a specific protein referred to as the binding protein. A combination of gel filterations and gel electrophoresis revealed that the binding protein is composed of a major 28 kd and a minor 29 kd protein. Both of the proteins were shown to be nonproteolytic by gelatin SDS-PAGE analysis and the amino acid composition analysis of the purified 28 kd protein revealed that it is not related to the proteolytic component of the proacrosinacrosin system. PMID:1519775

  10. Photoswitchable precision glycooligomers and their lectin binding

    PubMed Central

    Ponader, Daniela; Igde, Sinaida; Wehle, Marko; Märker, Katharina; Santer, Mark

    2014-01-01

    Summary The synthesis of photoswitchable glycooligomers is presented by applying solid-phase polymer synthesis and functional building blocks. The obtained glycoligands are monodisperse and present azobenzene moieties as well as sugar ligands at defined positions within the oligomeric backbone and side chains, respectively. We show that the combination of molecular precision together with the photoswitchable properties of the azobenzene unit allows for the photosensitive control of glycoligand binding to protein receptors. These stimuli-sensitive glycoligands promote the understanding of multivalent binding and will be further developed as novel biosensors. PMID:25161717

  11. Binding Energy Distribution Analysis Method: Hamiltonian Replica Exchange with Torsional Flattening for Binding Mode Prediction and Binding Free Energy Estimation.

    PubMed

    Mentes, Ahmet; Deng, Nan-Jie; Vijayan, R S K; Xia, Junchao; Gallicchio, Emilio; Levy, Ronald M

    2016-05-10

    Molecular dynamics modeling of complex biological systems is limited by finite simulation time. The simulations are often trapped close to local energy minima separated by high energy barriers. Here, we introduce Hamiltonian replica exchange (H-REMD) with torsional flattening in the Binding Energy Distribution Analysis Method (BEDAM), to reduce energy barriers along torsional degrees of freedom and accelerate sampling of intramolecular degrees of freedom relevant to protein-ligand binding. The method is tested on a standard benchmark (T4 Lysozyme/L99A/p-xylene complex) and on a library of HIV-1 integrase complexes derived from the SAMPL4 blind challenge. We applied the torsional flattening strategy to 26 of the 53 known binders to the HIV Integrase LEDGF site found to have a binding energy landscape funneled toward the crystal structure. We show that our approach samples the conformational space more efficiently than the original method without flattening when starting from a poorly docked pose with incorrect ligand dihedral angle conformations. In these unfavorable cases convergence to a binding pose within 2-3 Å from the crystallographic pose is obtained within a few nanoseconds of the Hamiltonian replica exchange simulation. We found that torsional flattening is insufficient in cases where trapping is due to factors other than torsional energy, such as the formation of incorrect intramolecular hydrogen bonds and stacking. Work is in progress to generalize the approach to handle these cases and thereby make it more widely applicable. PMID:27070865

  12. Can cofactor-binding sites in proteins be flexible? Desulfovibrio desulfuricans flavodoxin binds FMN dimer.

    PubMed

    Muralidhara, B K; Wittung-Stafshede, Pernilla

    2003-11-11

    Flavodoxins catalyze redox reactions using the isoalloxazine moiety of the flavin mononucleotide (FMN) cofactor stacked between two aromatic residues located in two peptide loops. At high FMN concentrations that favor stacked FMN dimers in solution, isothermal titration calorimetric studies show that these dimers bind strongly to apo-flavodoxin from Desulfovibrio desulfuricans (30 degrees C, 20 mM Hepes, pH 7, K(D) = 5.8 microM). Upon increasing the temperature so the FMN dimers dissociate (as shown by (1)H NMR), only one-to-one (FMN-to-protein) binding is observed. Calorimetric titrations result in one-to-one binding also in the presence of phosphate or sulfate (30 degrees C, 13 mM anion, pH 7, K(D) = 0.4 microM). FMN remains dimeric in the presence of phosphate and sulfate, suggesting that specific binding of a divalent anion to the phosphate-binding site triggers ordering of the peptide loops so only one isoalloxazine can fit. Although the physiological relevance of FMN and other nucleotides as dimers has not been explored, our study shows that high-affinity binding to proteins of such dimers can occur in vitro. This emphasizes that the cofactor-binding site in flavodoxin is more flexible than previously expected. PMID:14596623

  13. Coenzyme Q10-Binding/Transfer Protein Saposin B also Binds gamma-Tocopherol.

    PubMed

    Jin, Guangzhi; Horinouchi, Ryo; Sagawa, Tomofumi; Orimo, Nobutsune; Kubo, Hiroshi; Yoshimura, Shinichi; Fujisawa, Akio; Kashiba, Misato; Yamamoto, Yorihiro

    2008-09-01

    gamma-Tocopherol, the major form of dietary vitamin E, is absorbed in the intestine and is secreted in chylomicrons, which are then transferred to liver lysosomes. Most gamma-tocopherol is transferred to liver microsomes and is catabolized by cytochrome p450. Due to the hydrophobicity of gamma-tocopherol, a binding and transfer protein is plausible, but none have yet been isolated and characterized. We recently found that a ubiquitous cytosolic protein, saposin B, binds and transfers coenzyme Q10 (CoQ10), which is an essential factor for ATP production and an important antioxidant. Here, we report that saposin B also binds gamma-tocopherol, but not alpha-tocopherol, as efficiently as CoQ10 at pH 7.4. At acidic pH, saposin B binds gamma-tocopherol preferentially to CoQ10 and alpha-tocopherol. Furthermore, we confirmed that saposin B selectively binds gamma-tocopherol instead of CoQ10 and alpha-tocopherol at every pH between 5.4 and 8.0 when all three lipids are competing for binding. We detected gamma-tocopherol in human saposin B monoclonal antibody-induced immunoprecipitates from human urine, although the amount of gamma-tocopherol was much smaller than that of CoQ10. These results suggest that saposin B binds and transports gamma-tocopherol in human cells. PMID:18818759

  14. Solution structure and binding specificity of the p63 DNA binding domain.

    PubMed

    Enthart, Andreas; Klein, Christian; Dehner, Alexander; Coles, Murray; Gemmecker, Gerd; Kessler, Horst; Hagn, Franz

    2016-01-01

    p63 is a close homologue of p53 and, together with p73, is grouped into the p53 family of transcription factors. p63 is known to be involved in the induction of controlled apoptosis important for differentiation processes, germ line integrity and development. Despite its high homology to p53, especially within the DNA binding domain (DBD), p63-DBD does not show cooperative DNA binding properties and is significantly more stable against thermal and chemical denaturation. Here, we determined the solution structure of p63-DBD and show that it is markedly less dynamic than p53-DBD. In addition, we also investigate the effect of a double salt bridge present in p53-DBD, but not in p63-DBD on the cooperative binding behavior and specificity to various DNA sites. Restoration of the salt bridges in p63-DBD by mutagenesis leads to enhanced binding affinity to p53-specific, but not p63-specific response elements. Furthermore, we show that p63-DBD is capable of binding to anti-apoptotic BclxL via its DNA binding interface, a feature that has only been shown for p53 so far. These data suggest that all p53 family members - despite alterations in the specificity and binding affinity - are capable of activating pro-apoptotic pathways in a tissue specific manner. PMID:27225672

  15. A unique inhibitor binding site in ERK1/2 is associated with slow binding kinetics

    PubMed Central

    Chaikuad, Apirat; Tacconi, Eliana; Zimmer, Jutta; Liang, Yanke; Gray, Nathanael S.; Tarsounas, Madalena; Knapp, Stefan

    2014-01-01

    Activation of the ERK pathway is a hallmark of cancer and targeting of upstream signalling partners led to the development of approved drugs. Recently SCH772984 has been shown to be a selective and potent ERK1/2 inhibitor. Here we report the structural mechanism for its remarkable selectivity. In ERK1/2, SCH772984 induced a so far unknown binding pocket that accommodated the piperazine-phenyl-pyrimidine decoration. This novel binding pocket was created by an inactive conformation of the phosphate binding loop and an outward tilt of helix αC. In contrast, structure determination of SCH772984 with the off-target haspin and JNK1 revealed canonical but two distinct type-I binding modes. Intriguingly, the novel binding mode with ERK1/2 was associated with slow binding kinetics in vitro as well as in cell based assay systems. The described binding mode of SCH772984 with ERK1/2 enables the design of a new type of specific kinase inhibitors with prolonged on-target activity. PMID:25195011

  16. Solution structure and binding specificity of the p63 DNA binding domain

    PubMed Central

    Enthart, Andreas; Klein, Christian; Dehner, Alexander; Coles, Murray; Gemmecker, Gerd; Kessler, Horst; Hagn, Franz

    2016-01-01

    p63 is a close homologue of p53 and, together with p73, is grouped into the p53 family of transcription factors. p63 is known to be involved in the induction of controlled apoptosis important for differentiation processes, germ line integrity and development. Despite its high homology to p53, especially within the DNA binding domain (DBD), p63-DBD does not show cooperative DNA binding properties and is significantly more stable against thermal and chemical denaturation. Here, we determined the solution structure of p63-DBD and show that it is markedly less dynamic than p53-DBD. In addition, we also investigate the effect of a double salt bridge present in p53-DBD, but not in p63-DBD on the cooperative binding behavior and specificity to various DNA sites. Restoration of the salt bridges in p63-DBD by mutagenesis leads to enhanced binding affinity to p53-specific, but not p63-specific response elements. Furthermore, we show that p63-DBD is capable of binding to anti-apoptotic BclxL via its DNA binding interface, a feature that has only been shown for p53 so far. These data suggest that all p53 family members - despite alterations in the specificity and binding affinity - are capable of activating pro-apoptotic pathways in a tissue specific manner. PMID:27225672

  17. Binding Sites Analyser (BiSA): Software for Genomic Binding Sites Archiving and Overlap Analysis

    PubMed Central

    Khushi, Matloob; Liddle, Christopher; Clarke, Christine L.; Graham, J. Dinny

    2014-01-01

    Genome-wide mapping of transcription factor binding and histone modification reveals complex patterns of interactions. Identifying overlaps in binding patterns by different factors is a major objective of genomic studies, but existing methods to archive large numbers of datasets in a personalised database lack sophistication and utility. Therefore we have developed transcription factor DNA binding site analyser software (BiSA), for archiving of binding regions and easy identification of overlap with or proximity to other regions of interest. Analysis results can be restricted by chromosome or base pair overlap between regions or maximum distance between binding peaks. BiSA is capable of reporting overlapping regions that share common base pairs; regions that are nearby; regions that are not overlapping; and average region sizes. BiSA can identify genes located near binding regions of interest, genomic features near a gene or locus of interest and statistical significance of overlapping regions can also be reported. Overlapping results can be visualized as Venn diagrams. A major strength of BiSA is that it is supported by a comprehensive database of publicly available transcription factor binding sites and histone modifications, which can be directly compared to user data. The documentation and source code are available on http://bisa.sourceforge.net PMID:24533055

  18. Non-binding relationship between visual features.

    PubMed

    Rangelov, Dragan; Zeki, Semir

    2014-01-01

    The answer as to how visual attributes processed in different brain loci at different speeds are bound together to give us our unitary experience of the visual world remains unknown. In this study we investigated whether bound representations arise, as commonly assumed, through physiological interactions between cells in the visual areas. In a focal attentional task in which correct responses from either bound or unbound representations were possible, participants discriminated the color or orientation of briefly presented single bars. On the assumption that representations of the two attributes are bound, the accuracy of reporting the color and orientation should co-vary. By contrast, if the attributes are not mandatorily bound, the accuracy of reporting the two attributes should be independent. The results of our psychophysical studies reported here supported the latter, non-binding, relationship between visual features, suggesting that binding does not necessarily occur even under focal attention. We propose a task-contingent binding mechanism, postulating that binding occurs at late, post-perceptual (PP), stages through the intervention of memory. PMID:25339879

  19. Inhibition of histone binding by supramolecular hosts

    PubMed Central

    Allen, Hillary F.; Daze, Kevin D.; Shimbo, Takashi; Lai, Anne; Musselman, Catherine A.; Sims, Jennifer K.; Wade, Paul A.; Hof†, Fraser; Kutateladze, Tatiana G.

    2015-01-01

    The tandem PHD (plant homeodomain) fingers of the CHD4 (chromodomain helicase DNA-binding protein 4) ATPase are epigenetic readers that bind either unmodified histone H3 tails or H3K9me3 (histone H3 trimethylated at Lys9). This dual function is necessary for the transcriptional and chromatin remodelling activities of the NuRD (nucleosome remodelling and deacetylase) complex. In the present paper, we show that calixarene-based supramolecular hosts disrupt binding of the CHD4 PHD2 finger to H3K9me3, but do not affect the interaction of this protein with the H3K9me0 (unmodified histone H3) tail. A similar inhibitory effect, observed for the association of chromodomain of HP1γ (heterochromatin protein 1γ) with H3K9me3, points to a general mechanism of methyl-lysine caging by calixarenes and suggests a high potential for these compounds in biochemical applications. Immunofluorescence analysis reveals that the supramolecular agents induce changes in chromatin organization that are consistent with their binding to and disruption of H3K9me3 sites in living cells. The results of the present study suggest that the aromatic macrocyclic hosts can be used as a powerful new tool for characterizing methylation-driven epigenetic mechanisms. PMID:24576085

  20. The Cultural Bind on the American Male

    ERIC Educational Resources Information Center

    Chenoweth, Gene

    2012-01-01

    In this article, the author talks about the cultural bind on the American male. The process starts with conception. If the spermatozoid that fertilizes the egg contains only X chromosomes a girl will be produced. If a single Y chromosome out of the 24 produced by the father is included, the baby will be a boy. From this point on the girls have a…

  1. The complex binding of PRDM9

    PubMed Central

    2013-01-01

    A recent study investigates the in vitro DNA binding behavior of PRDM9, a zinc finger protein involved in the localization of recombination hotspots in mammals. Please see related research article: http://genomebiology.com/2013/14/4/R35 PMID:23651476

  2. [Carbohydrate-binding proteins of marine invertebrates].

    PubMed

    Luk'ianov, P A; Chernikov, O V; Kobelev, S S; Chikalovets, I V; Molchanova, V I; Li, W

    2007-01-01

    The information on the carbohydrate specificity and molecular organization of some carbohydrate-binding proteins (lectins) of marine invertebrates is reported. Antiviral activity of some of the lectins against human immunodeficiency virus has been studied. Lectins of marine invertebrates are promising tools for studying natural glycoconjugates and cell effectors in vitro. PMID:17375673

  3. The Binding Properties of Quechua Suffixes.

    ERIC Educational Resources Information Center

    Weber, David

    This paper sketches an explicitly non-lexicalist application of grammatical theory to Huallaga (Huanuco) Quechua (HgQ). The advantages of applying binding theory to many suffixes that have previously been treated only as objects of the morphology are demonstrated. After an introduction, section 2 outlines basic assumptions about the nature of HgQ…

  4. Dynamics of Transcription Factor Binding Site Evolution

    PubMed Central

    Tuğrul, Murat; Paixão, Tiago; Barton, Nicholas H.; Tkačik, Gašper

    2015-01-01

    Evolution of gene regulation is crucial for our understanding of the phenotypic differences between species, populations and individuals. Sequence-specific binding of transcription factors to the regulatory regions on the DNA is a key regulatory mechanism that determines gene expression and hence heritable phenotypic variation. We use a biophysical model for directional selection on gene expression to estimate the rates of gain and loss of transcription factor binding sites (TFBS) in finite populations under both point and insertion/deletion mutations. Our results show that these rates are typically slow for a single TFBS in an isolated DNA region, unless the selection is extremely strong. These rates decrease drastically with increasing TFBS length or increasingly specific protein-DNA interactions, making the evolution of sites longer than ∼ 10 bp unlikely on typical eukaryotic speciation timescales. Similarly, evolution converges to the stationary distribution of binding sequences very slowly, making the equilibrium assumption questionable. The availability of longer regulatory sequences in which multiple binding sites can evolve simultaneously, the presence of “pre-sites” or partially decayed old sites in the initial sequence, and biophysical cooperativity between transcription factors, can all facilitate gain of TFBS and reconcile theoretical calculations with timescales inferred from comparative genomics. PMID:26545200

  5. Metal binding components in human amniotic fluid

    SciTech Connect

    Paterson, P.G.; Zlotkin, S.H.; Sarkar, B. )

    1990-02-26

    Amniotic fluid is a potential source of both nutritionally essential and toxic metals for the fetus. As the binding pattern of these metals in amniotic fluid may be one of the determining factors in their availability to the fetus, the objective of this study was to investigate metal binding in vitro. The binding of six trace metals, Mn(II), Ni(II), Zn(II), Cu(II), Cd(II), and Fe(III), to components of human amniotic fluid was studied by Sephadex G-100 gel filtration at physiological pH, using radioisotopes as tracers and 50 mM TRIS/HCl as the elution buffer. The amniotic fluid was collected at 16-16.5 weeks gestation by amniocentesis and pooled for analysis. Extensive amounts of Fe, Cu, Zn, and Cd and small amounts of Mn and Ni were bound to high molecular weight proteins with elution patterns similar to those seen for the binding of these metals in serum. In addition, large amounts of Fe, Mn, Ni and Cd and small amounts of Zn and Cu were associated with low molecular weight component(s). The identity of these latter components is unknown, but they play an important biological role in amniotic fluid.

  6. The Double Bind: The next Generation

    ERIC Educational Resources Information Center

    Malcom, Lindsey E.; Malcom, Shirley M.

    2011-01-01

    In this foreword, Shirley Malcom and Lindsey Malcom speak to the history and current status of women of color in science, technology, engineering, and mathematics (STEM) fields. As the author of the seminal report "The Double Bind: The Price of Being a Minority Woman in Science", Shirley Malcom is uniquely poised to give us an insightful…

  7. Nucleic acids encoding a cellulose binding domain

    DOEpatents

    Shoseyov, Oded; Shpiegl, Itai; Goldstein, Marc A.; Doi, Roy H.

    1996-01-01

    A cellulose binding domain (CBD) having a high affinity for crystalline cellulose and chitin is disclosed, along with methods for the molecular cloning and recombinant production thereof. Fusion products comprising the CBD and a second protein are likewise described. A wide range of applications are contemplated for both the CBD and the fusion products, including drug delivery, affinity separations, and diagnostic techniques.

  8. Nucleic acids encoding a cellulose binding domain

    DOEpatents

    Shoseyov, O.; Shpiegl, I.; Goldstein, M.A.; Doi, R.H.

    1996-03-05

    A cellulose binding domain (CBD) having a high affinity for crystalline cellulose and chitin is disclosed, along with methods for the molecular cloning and recombinant production. Fusion products comprising the CBD and a second protein are likewise described. A wide range of applications are contemplated for both the CBD and the fusion products, including drug delivery, affinity separations, and diagnostic techniques. 15 figs.

  9. Nebulin binding impedes mutant desmin filament assembly

    PubMed Central

    Baker, Laura K.; Gillis, David C.; Sharma, Sarika; Ambrus, Andy; Herrmann, Harald; Conover, Gloria M.

    2013-01-01

    Desmin intermediate filaments (DIFs) form an intricate meshwork that organizes myofibers within striated muscle cells. The mechanisms that regulate the association of desmin to sarcomeres and their role in desminopathy are incompletely understood. Here we compare the effect nebulin binding has on the assembly kinetics of desmin and three desminopathy-causing mutant desmin variants carrying mutations in the head, rod, or tail domains of desmin (S46F, E245D, and T453I). These mutants were chosen because the mutated residues are located within the nebulin-binding regions of desmin. We discovered that, although nebulin M160–164 bound to both desmin tetrameric complexes and mature filaments, all three mutants exhibited significantly delayed filament assembly kinetics when bound to nebulin. Correspondingly, all three mutants displayed enhanced binding affinities and capacities for nebulin relative to wild-type desmin. Electron micrographs showed that nebulin associates with elongated normal and mutant DIFs assembled in vitro. Moreover, we measured significantly delayed dynamics for the mutant desmin E245D relative to wild-type desmin in fluorescence recovery after photobleaching in live-cell imaging experiments. We propose a mechanism by which mutant desmin slows desmin remodeling in myocytes by retaining nebulin near the Z-discs. On the basis of these data, we suggest that for some filament-forming desmin mutants, the molecular etiology of desminopathy results from subtle deficiencies in their association with nebulin, a major actin-binding filament protein of striated muscle. PMID:23615443

  10. Cross-Modal Binding in Developmental Dyslexia

    ERIC Educational Resources Information Center

    Jones, Manon W.; Branigan, Holly P.; Parra, Mario A.; Logie, Robert H.

    2013-01-01

    The ability to learn visual-phonological associations is a unique predictor of word reading, and individuals with developmental dyslexia show impaired ability in learning these associations. In this study, we compared developmentally dyslexic and nondyslexic adults on their ability to form cross-modal associations (or "bindings") based…

  11. Stabilized sulfur binding using activated fillers

    DOEpatents

    Kalb, Paul D.; Vagin, Vyacheslav P.; Vagin, Sergey P.

    2015-07-21

    A method of making a stable, sulfur binding composite comprising impregnating a solid aggregate with an organic modifier comprising unsaturated hydrocarbons with at least one double or triple covalent bond between adjacent carbon atoms to create a modifier-impregnated aggregate; heating and drying the modifier-impregnated aggregate to activate the surface of the modifier-impregnated aggregate for reaction with sulfur.

  12. Oxytocin binding sites in bovine mammary tissue

    SciTech Connect

    Zhao, Xin.

    1989-01-01

    Oxytocin binding sites were identified and characterized in bovine mammary tissue. ({sup 3}H)-oxytocin binding reached equilibrium by 50 min at 20{degree}C and by 8 hr at 4{degree}C. The half-time of displacement at 20{degree}C was approximately 1 hr. Thyrotropin releasing hormone, adrenocorticotropin, angiotensin I, angiotensin II, pentagastrin, bradykinin, xenopsin and L-valyl-histidyl-L-leucyl-L-threonyl-L-prolyl-L-valyl-L-glutamyl-L-lysine were not competitive. In the presence of 10 nM LiCl, addition of oxytocin to dispersed bovine mammary cells, in which phosphatidylinositol was pre-labelled, caused a time and dose-dependent increase in radioactive inositiol monophosphate incorporation. The possibility that there are distinct vasopressin receptors in bovine mammary tissue was investigated. ({sup 3}H)-vasopressin binding reached equilibrium by 40 min at 20{degree}. The half-time of displacement at 20{degree}C was approximately 1 hr. The ability of the peptides to inhibit ({sup 3}H)-vasopressin binding was: (Thr{sup 4},Gly{sup 7})-oxytocin > Arg{sup 8}-vasopressin > (lys{sup 8})-vasopressin > (Deamino{sup 1},D-arg{sup 8})-vasopressin > oxytocin > d (CH{sub 2}){sub 5}Tyr(Me)AVP.

  13. Binding of NAD+ to pertussis toxin.

    PubMed

    Lobban, M D; Irons, L I; van Heyningen, S

    1991-06-24

    The equilibrium dissociation constant of NAD+ and pertussis toxin was determined by equilibrium dialysis and by the quenching of the protein's intrinsic fluorescence on titration with NAD+. A binding constant, Kd, of 24 +/- 2 microM at 30 degrees C was obtained from equilibrium dialysis, consistent with the previously determined value for the Michaelis constant, Km, of 30 +/- 5 microM for NAD+ (when the toxin is catalysing the ADP-ribosylation of water and of dithiothreitol). The intrinsic fluorescence of pertussis toxin was quenched by up to 60% on titration with NAD+, and after correction for dilution and inner filter effects, a Kd value of 27 microM at 30 degrees C was obtained, agreeing well with that found by equilibrium dialysis. The binding constants were measured at a number of temperatures using both techniques, and from this the enthalpy of binding of NAD+ to toxin was determined to be 30 kJ.mol-1, a typical value for a protein-ligand interaction. There is one binding site for NAD+ per toxin molecule. PMID:1648404

  14. Universal binding energy relations in metallic adhesion

    NASA Technical Reports Server (NTRS)

    Ferrante, J.; Smith, J. R.; Rose, J. J.

    1984-01-01

    Rose, Smith, and Ferrante have discovered scaling relations which map the adhesive binding energy calculated by Ferrante and Smith onto a single universal binding energy curve. These binding energies are calculated for all combinations of Al(111), Zn(0001), Mg(0001), and Na(110) in contact. The scaling involves normalizing the energy by the maximum binding energy and normalizing distances by a suitable combination of Thomas-Fermi screening lengths. Rose et al. have also found that the calculated cohesive energies of K, Ba, Cu, Mo, and Sm scale by similar simple relations, suggesting the universal relation may be more general than for the simple free electron metals for which it was derived. In addition, the scaling length was defined more generally in order to relate it to measurable physical properties. Further this universality can be extended to chemisorption. A simple and yet quite accurate prediction of a zero temperature equation of state (volume as a function of pressure for metals and alloys) is presented. Thermal expansion coefficients and melting temperatures are predicted by simple, analytic expressions, and results compare favorably with experiment for a broad range of metals.

  15. The Case against Binding Interest Arbitration.

    ERIC Educational Resources Information Center

    Ecker, Charles I.

    1984-01-01

    The author contends that districts should reject binding interest arbitration as a means of resolving an impasse in contract negotiations, charging that it hampers good faith bargaining, adversely affects fiscal and operational management of the school system, and diminishes the governing role of the board of education. (MJL)

  16. Predicting ligand binding affinity with alchemical free energy methods in a polar model binding site

    PubMed Central

    Boyce, Sarah E.; Mobley, David L.; Rocklin, Gabriel; Graves, Alan P.

    2009-01-01

    We present a combined experimental and modeling study of organic ligand molecules binding to a slightly polar engineered cavity site in T4 lysozyme (L99A/M102Q). For modeling, we computed alchemical absolute binding free energies. These were blind tests performed prospectively on 13 diverse, previously untested candidate ligand molecules. We predicted that eight compounds would bind to the cavity and five would not; 11 of 13 predictions were correct at this level. The RMS error to the measurable absolute binding energies was 1.8 kcal/mol. In addition, we computed relative binding free energies for six phenol derivatives starting from two known ligands: phenol and catechol. The average RMS error in the relative free energy prediction was 2.5 (phenol) and 1.1 (catechol) kcal/mol. To understand these results at atomic resolution, we obtained x-ray co-complex structures for nine of the diverse ligands and for all six phenol analogs. The average RMSD of the predicted pose to the experiment was 2.0Å (diverse set), 1.8Å (phenol derived predictions) and 1.2Å (catechol derived predictions). We found that to predict accurate affinities and rank-orderings required near-native starting orientations of the ligand in the binding site. Unanticipated binding modes, multiple ligand binding, and protein conformational change all proved challenging for the free energy methods. We believe these results can help guide future improvements in physics-based absolute binding free energy methods. PMID:19782087

  17. Exploration of dimensions of estrogen potency: parsing ligand binding and coactivator binding affinities.

    PubMed

    Jeyakumar, M; Carlson, Kathryn E; Gunther, Jillian R; Katzenellenbogen, John A

    2011-04-15

    The estrogen receptors, ERα and ERβ, are ligand-regulated transcription factors that control gene expression programs in target tissues. The molecular events underlying estrogen action involve minimally two steps, hormone binding to the ER ligand-binding domain followed by coactivator recruitment to the ER·ligand complex; this ligand·receptor·coactivator triple complex then alters gene expression. Conceptually, the potency of an estrogen in activating a cellular response should reflect the affinities that characterize both steps involved in the assembly of the active ligand·receptor·coactivator complex. Thus, to better understand the molecular basis of estrogen potency, we developed a completely in vitro system (using radiometric and time-resolved FRET assays) to quantify independently three parameters: (a) the affinity of ligand binding to ER, (b) the affinity of coactivator binding to the ER·ligand complex, and (c) the potency of ligand recruitment of coactivator. We used this system to characterize the binding and potency of 12 estrogens with both ERα and ERβ. Some ligands showed good correlations between ligand binding affinity, coactivator binding affinity, and coactivator recruitment potency with both ERs, whereas others showed correlations with only one ER subtype or displayed discordant coactivator recruitment potencies. When ligands with low receptor binding affinity but high coactivator recruitment potencies to ERβ were evaluated in cell-based assays, elevation of cellular coactivator levels significantly and selectively improved their potency. Collectively, our results indicate that some low affinity estrogens may elicit greater cellular responses in those target cells that express higher levels of specific coactivators capable of binding to their ER complexes with high affinity. PMID:21321128

  18. Binding Site Graphs: A New Graph Theoretical Framework for Prediction of Transcription Factor Binding Sites

    PubMed Central

    Reddy, Timothy E; DeLisi, Charles; Shakhnovich, Boris E

    2007-01-01

    Computational prediction of nucleotide binding specificity for transcription factors remains a fundamental and largely unsolved problem. Determination of binding positions is a prerequisite for research in gene regulation, a major mechanism controlling phenotypic diversity. Furthermore, an accurate determination of binding specificities from high-throughput data sources is necessary to realize the full potential of systems biology. Unfortunately, recently performed independent evaluation showed that more than half the predictions from most widely used algorithms are false. We introduce a graph-theoretical framework to describe local sequence similarity as the pair-wise distances between nucleotides in promoter sequences, and hypothesize that densely connected subgraphs are indicative of transcription factor binding sites. Using a well-established sampling algorithm coupled with simple clustering and scoring schemes, we identify sets of closely related nucleotides and test those for known TF binding activity. Using an independent benchmark, we find our algorithm predicts yeast binding motifs considerably better than currently available techniques and without manual curation. Importantly, we reduce the number of false positive predictions in yeast to less than 30%. We also develop a framework to evaluate the statistical significance of our motif predictions. We show that our approach is robust to the choice of input promoters, and thus can be used in the context of predicting binding positions from noisy experimental data. We apply our method to identify binding sites using data from genome scale ChIP–chip experiments. Results from these experiments are publicly available at http://cagt10.bu.edu/BSG. The graphical framework developed here may be useful when combining predictions from numerous computational and experimental measures. Finally, we discuss how our algorithm can be used to improve the sensitivity of computational predictions of transcription factor

  19. Predicting binding within disordered protein regions to structurally characterised peptide-binding domains.

    PubMed

    Khan, Waqasuddin; Duffy, Fergal; Pollastri, Gianluca; Shields, Denis C; Mooney, Catherine

    2013-01-01

    Disordered regions of proteins often bind to structured domains, mediating interactions within and between proteins. However, it is difficult to identify a priori the short disordered regions involved in binding. We set out to determine if docking such peptide regions to peptide binding domains would assist in these predictions.We assembled a redundancy reduced dataset of SLiM (Short Linear Motif) containing proteins from the ELM database. We selected 84 sequences which had an associated PDB structures showing the SLiM bound to a protein receptor, where the SLiM was found within a 50 residue region of the protein sequence which was predicted to be disordered. First, we investigated the Vina docking scores of overlapping tripeptides from the 50 residue SLiM containing disordered regions of the protein sequence to the corresponding PDB domain. We found only weak discrimination of docking scores between peptides involved in binding and adjacent non-binding peptides in this context (AUC 0.58).Next, we trained a bidirectional recurrent neural network (BRNN) using as input the protein sequence, predicted secondary structure, Vina docking score and predicted disorder score. The results were very promising (AUC 0.72) showing that multiple sources of information can be combined to produce results which are clearly superior to any single source.We conclude that the Vina docking score alone has only modest power to define the location of a peptide within a larger protein region known to contain it. However, combining this information with other knowledge (using machine learning methods) clearly improves the identification of peptide binding regions within a protein sequence. This approach combining docking with machine learning is primarily a predictor of binding to peptide-binding sites, and is not intended as a predictor of specificity of binding to particular receptors. PMID:24019881

  20. Perturbation Approaches for Exploring Protein Binding Site Flexibility to Predict Transient Binding Pockets.

    PubMed

    Kokh, Daria B; Czodrowski, Paul; Rippmann, Friedrich; Wade, Rebecca C

    2016-08-01

    Simulations of the long-time scale motions of a ligand binding pocket in a protein may open up new perspectives for the design of compounds with steric or chemical properties differing from those of known binders. However, slow motions of proteins are difficult to access using standard molecular dynamics (MD) simulations and are thus usually neglected in computational drug design. Here, we introduce two nonequilibrium MD approaches to identify conformational changes of a binding site and detect transient pockets associated with these motions. The methods proposed are based on the rotamerically induced perturbation (RIP) MD approach, which employs perturbation of side-chain torsional motion for initiating large-scale protein movement. The first approach, Langevin-RIP (L-RIP), entails a series of short Langevin MD simulations, each starting with perturbation of one of the side-chains lining the binding site of interest. L-RIP provides extensive sampling of conformational changes of the binding site. In less than 1 ns of MD simulation with L-RIP, we observed distortions of the α-helix in the ATP binding site of HSP90 and flipping of the DFG loop in Src kinase. In the second approach, RIPlig, a perturbation is applied to a pseudoligand placed in different parts of a binding pocket, which enables flexible regions of the binding site to be identified in a small number of 10 ps MD simulations. The methods were evaluated for four test proteins displaying different types and degrees of binding site flexibility. Both methods reveal all transient pocket regions in less than a total of 10 ns of simulations, even though many of these regions remained closed in 100 ns conventional MD. The proposed methods provide computationally efficient tools to explore binding site flexibility and can aid in the functional characterization of protein pockets, and the identification of transient pockets for ligand design. PMID:27399277

  1. Detergent binding as a sensor of hydrophobicity and polar interactions in the binding cavities of proteins.

    PubMed

    Peyre, Véronique; Lair, Virginie; André, Virginie; le Maire, Guerric; Kragh-Hansen, Ulrich; le Maire, Marc; Møller, Jesper V

    2005-09-13

    To evaluate the role of hydrophobic and electrostatic or other polar interactions for protein-ligand binding, we studied the interaction of human serum albumin (HSA) and beta-lactoglobulin with various aliphatic (C10-C14) cationic and zwitterionic detergents. We find that cationic detergents, at levels that do not cause unfolding, interact with a single site on beta-lactoglobulin and with two primary and five to six secondary sites on HSA with an affinity that is approximately the same as that with which zwitterionic (dimethylamineoxide) detergents interact, suggesting the absence of significant electrostatic interactions in the high-affinity binding of these compounds. The binding affinity for all of the groups of compounds was dependent upon hydrocarbon chain length, suggesting the predominant role of hydrophobic forces, supported by polar interactions at the protein surface. A distinct correlation between the binding energy and the propensity for micelle formation within the group of cationic or noncharged (nonionic and zwitterionic) detergents indicated that the critical micellar concentration (CMC) for each of these detergent groups, rather than the absolute length of the hydrocarbon chain, can be used to compare their hydrophobicities during their interaction with protein. Intrinsic fluorescence data suggest that the two primary binding sites on serum albumin for the zwitterionic and cationic compounds are located in the C-terminal part of the albumin molecule, possibly in the Sudlow II binding region. Comparisons with previous binding data on anionic amphiphiles emphasize the important contribution of ion bond formation and other polar interactions in the binding of fatty acids and dodecyl sulfate (SDS) by HSA but not by beta-lactoglobulin. Electrostatic interactions by cationic detergents played a significant role in destabilizing the protein structure at high binding levels, with beta-lactoglobulin being more susceptible to unfolding than HSA. Zwitterionic

  2. CD36 Binds Oxidized Low Density Lipoprotein (LDL) in a Mechanism Dependent upon Fatty Acid Binding*

    PubMed Central

    Jay, Anthony G.; Chen, Alexander N.; Paz, Miguel A.; Hung, Justin P.; Hamilton, James A.

    2015-01-01

    The association of unesterified fatty acid (FA) with the scavenger receptor CD36 has been actively researched, with focuses on FA and oxidized low density lipoprotein (oxLDL) uptake. CD36 has been shown to bind FA, but this interaction has been poorly characterized to date. To gain new insights into the physiological relevance of binding of FA to CD36, we characterized FA binding to the ectodomain of CD36 by the biophysical method surface plasmon resonance. Five structurally distinct FAs (saturated, monounsaturated (cis and trans), polyunsaturated, and oxidized) were pulsed across surface plasmon resonance channels, generating association and dissociation binding curves. Except for the oxidized FA HODE, all FAs bound to CD36, with rapid association and dissociation kinetics similar to HSA. Next, to elucidate the role that each FA might play in CD36-mediated oxLDL uptake, we used a fluorescent oxLDL (Dii-oxLDL) live cell assay with confocal microscopy imaging. CD36-mediated uptake in serum-free medium was very low but greatly increased when serum was present. The addition of exogenous FA in serum-free medium increased oxLDL binding and uptake to levels found with serum and affected CD36 plasma membrane distribution. Binding/uptake of oxLDL was dependent upon the FA dose, except for docosahexaenoic acid, which exhibited binding to CD36 but did not activate the uptake of oxLDL. HODE also did not affect oxLDL uptake. High affinity FA binding to CD36 and the effects of each FA on oxLDL uptake have important implications for protein conformation, binding of other ligands, functional properties of CD36, and high plasma FA levels in obesity and type 2 diabetes. PMID:25555908

  3. Nucleolin is a calcium-binding protein.

    PubMed

    Gilchrist, James S C; Abrenica, Bernard; DiMario, Patrick J; Czubryt, Michael P; Pierce, Grant N

    2002-01-01

    We have purified a prominent 110-kDa protein (p110) from 1.6 M NaCl extracts of rat liver nuclei that appears to bind Ca2+. p110 was originally identified by prominent blue staining with 'Stains-All' in sodium dodecyl sulfate-polyacrylamide gels and was observed to specifically bind ruthenium red and 45Ca2+ in nitrocellulose blot overlays. In spin-dialysis studies, purified p110 saturably bound approximately 75 nmol Ca2+/mg protein at a concentration of 1 mM total Ca2+ with half-maximal binding observed at 105 microM Ca2+. With purification, p110 became increasingly susceptible to proteolytic (likely autolytic) fragmentation, although most intermediary peptides between 40 and 90 kDa retained "Stains-All", ruthenium red, and 45Ca2+ binding. N-terminal sequencing of intact p110 and a 70-kDa autolytic peptide fragment revealed a strong homology to nucleolin. Two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE)/IEF revealed autolysis produced increasingly acidic peptide fragments ranging in apparent pI's from 5.5 for intact p110 to 3.5 for a 40 kDa peptide fragment. Intact p110 and several peptide fragments were immunostained with a highly specific anti-nucleolin antibody, R2D2, thus confirming the identity of this protein with nucleolin. These annexin-like Ca2+-binding characteristics of nucleolin are likely contributed by its highly acidic argyrophilic N-terminus with autolysis apparently resulting in largely selective removal of its basic C-terminal domain. Although the Ca2+-dependent functions of nucleolin are unknown, we discuss the possibility that like the structurally analogous HMG-1, its Ca2+-dependent actions may regulate chromatin structure, possibly during apoptosis. PMID:11948683

  4. Molecular anatomy of the antibody binding site.

    PubMed

    Novotný, J; Bruccoleri, R; Newell, J; Murphy, D; Haber, E; Karplus, M

    1983-12-10

    The binding region of immunoglobulins, which includes the portion of the molecule having the most variability in its amino acid sequence, is shown to have a surprisingly constant structure that can be characterized in terms of a simple, well-defined model. The binding region is composed of the antigen combining site plus its immediate vicinity and arises by noncovalent association of the light and heavy chain variable domains (VL and VH, respectively). The antigen combining site itself consists of six polypeptide chain segments ("hypervariable loops") which comprise some 80 amino acid residues and are attached to a framework of VL and VH beta-sheet bilayers. Having analyzed refined x-ray crystallographic coordinates for three antigen-binding fragments (Fab KOL (Marquart, M., Deisenhofer, J., and Huber, R. (1980) J. Mol. Biol. 141, 369-391), MCPC 603 (Segal, D., Padlan, E. A., Cohen, G. H., Rudikoff, S., Potter, M., and Davies, D. R. (1974) Proc. Natl. Acad. Sci. U. S. A. 71, 4298-4302), and NEW (Saul, F. A., Amzel, L. M., and Poljak, R. J. (1978) J. Biol. Chem. 253, 585-597] we use the results to introduce a general model for the VL-VH interface forming the binding region. The region consists of two closely packed beta-sheets, and its geometry corresponds to a 9-stranded, cylindrical barrel of average radius 0.84 nm with an average angle of -53 degrees between its two constituent beta-sheets. The barrel forms the bottom and sides of the antigen combining site. The model demonstrates that the structural variability of the binding region is considerably less than was thought previously. Amino acid residues which are part of the domain-domain interface and appear not to be accessible to solvent or antigen contribute to antibody specificity. PMID:6643494

  5. Metal binding stoichiometry and isotherm choice in biosorption

    SciTech Connect

    Schiewer, S.; Wong, M.H.

    1999-11-01

    Seaweeds that possess a high metal binding capacity may be used as biosorbents for the removal of toxic heavy metals from wastewater. The binding of Cu and Ni by three brown algae (Sargassum, Colpomenia, Petalonia) and one green alga (Ulva) was investigated at pH 4.0 and pH 3.0. The greater binding strength of Cu is reflected in a binding constant that is about 10 times as high as that of Ni. The extent of metal binding followed the order Petalonia {approximately} Sargassum > Colpomenia > Ulva. This was caused by a decreasing number of binding sites and by much lower metal binding constants for Ulva as compared to the brown algae. Three different stoichiometric assumptions are compared for describing the metal binding, which assume either that each metal ion M binds to one binding site B forming a BM complex or that a divalent metal ion M binds to two monovalent sites B forming BM{sub 0.5} or B{sub 2}M complexes, respectively. Stoichiometry plots are proposed as tools to discern the relevant binding stoichiometry. The pH effect in metal binding and the change in proton binding were well predicted for the B{sub 2}M or BM{sub 0.5} stoichiometries with the former being better for Cu and the latter preferable for Ni. Overall, the BM{sub 0.5} model is recommended because it avoids iterations.

  6. Development of more efficacious Tc-99m organ imaging agents for use in nuclear medicine by analytical characterization of radiopharmaceutical mixtures. Progress report, September 1, 1989--January 31, 1992

    SciTech Connect

    Heineman, W.R.

    1992-01-24

    The long-range objective of this research program is the development of more efficacious technetium-99m radiopharmaceuticals for use as imaging agents in diagnostic nuclear medicine. We seek to isolate and develop distinct site imaging agents, each of which has properties optimized to provide diagnostic information concerning a given pathological condition. The specific objectives during the period (9/1/89 to 8/31/92) include: (1) Development of strategies for improving yields of specific Tc-diphosphonate complexes with optimum imaging properties; (2) Development of electrodes for rapid in situ electrochemical generation of skeletal imaging agents; (3) Development of electrochemical sensors for {Tc} and Re imaging agents; (4) Characterization of stable {Tc}- and Re-diphosphonate complexes obtainable in high yield by structural studies with techniques such as NMR, EXAFS, and Raman spectroscopy; (5) Development of improved separation techniques for the characterization of diphosphonate skeletal imaging agents; (6) Evaluation of the effect of the biological milieu on {Tc}-diphosphonate complexes; and (7) Electrochemical studies of technetium and rhenium complexes synthesized by Professor Deutsch`s research group for heart and brain imaging.

  7. Multiple Binding Poses in the Hydrophobic Cavity of Bee Odorant Binding Protein AmelOBP14.

    PubMed

    Pechlaner, Maria; Oostenbrink, Chris

    2015-12-28

    In the first step of olfaction, odorants are bound and solubilized by small globular odorant binding proteins (OBPs) which shuttle them to the membrane of a sensory neuron. Low ligand affinity and selectivity at this step enable the recognition of a wide range of chemicals. Honey bee Apis mellifera's OBP14 (AmelOBP14) binds different plant odorants in a largely hydrophobic cavity. In long molecular dynamics simulations in the presence and absence of ligand eugenol, we observe a highly dynamic C-terminal region which forms one side of the ligand-binding cavity, and the ligand drifts away from its crystallized orientation. Hamiltonian replica exchange simulations, allowing exchanges of conformations sampled by the real ligand with those sampled by a noninteracting dummy molecule and several intermediates, suggest an alternative, quite different ligand pose which is adopted immediately and which is stable in long simulations. Thermodynamic integration yields binding free energies which are in reasonable agreement with experimental data. PMID:26633245

  8. Structural analysis of ibuprofen binding to human adipocyte fatty-acid binding protein (FABP4)

    PubMed Central

    González, Javier M.; Fisher, S. Zoë

    2015-01-01

    Inhibition of human adipocyte fatty-acid binding protein (FABP4) has been proposed as a treatment for type 2 diabetes, fatty liver disease and atherosclerosis. However, FABP4 displays a naturally low selectivity towards hydrophobic ligands, leading to the possibility of side effects arising from cross-inhibition of other FABP isoforms. In a search for structural determinants of ligand-binding selectivity, the binding of FABP4 towards a group of small molecules structurally related to the nonsteroidal anti-inflammatory drug ibuprofen was analyzed through X-ray crystallography. Several specific hydrophobic interactions are shown to enhance the binding affinities of these compounds, whereas an aromatic edge-to-face interaction is proposed to determine the conformation of bound ligands, highlighting the importance of aromatic interactions in hydrophobic environments. PMID:25664790

  9. Structure of the RNA-Binding Domain of Telomerase: Implications For RNA Recognition and Binding

    SciTech Connect

    Rouda,S.; Skordalakes, E.

    2007-01-01

    Telomerase, a ribonucleoprotein complex, replicates the linear ends of eukaryotic chromosomes, thus taking care of the 'end of replication problem.' TERT contains an essential and universally conserved domain (TRBD) that makes extensive contacts with the RNA (TER) component of the holoenzyme, and this interaction is thought to facilitate TERT/TER assembly and repeat-addition processivity. Here, we present a high-resolution structure of TRBD from Tetrahymena thermophila. The nearly all-helical structure comprises a nucleic acid-binding fold suitable for TER binding. An extended pocket on the surface of the protein, formed by two conserved motifs (CP and T motifs) comprises TRBD's RNA-binding pocket. The width and the chemical nature of this pocket suggest that it binds both single- and double-stranded RNA, possibly stem I, and the template boundary element (TBE). Moreover, the structure provides clues into the role of this domain in TERT/TER stabilization and telomerase repeat-addition processivity.

  10. Binding of transition metals to S100 proteins.

    PubMed

    Gilston, Benjamin A; Skaar, Eric P; Chazin, Walter J

    2016-08-01

    The S100 proteins are a unique class of EF-hand Ca(2+) binding proteins distributed in a cell-specific, tissue-specific, and cell cycle-specific manner in humans and other vertebrates. These proteins are distinguished by their distinctive homodimeric structure, both intracellular and extracellular functions, and the ability to bind transition metals at the dimer interface. Here we summarize current knowledge of S100 protein binding of Zn(2+), Cu(2+) and Mn(2+) ions, focusing on binding affinities, conformational changes that arise from metal binding, and the roles of transition metal binding in S100 protein function. PMID:27430886

  11. Evidence for an intrinsic binding force between dodecaborate dianions and receptors with hydrophobic binding pockets.

    PubMed

    Warneke, Jonas; Jenne, Carsten; Bernarding, Johannes; Azov, Vladimir A; Plaumann, Markus

    2016-05-01

    A gas phase binding study revealed strong intrinsic intermolecular interactions between dianionic halogenated closo-dodecaborates [B12X12](2-) and several neutral organic receptors. Oxidation of a tetrathiafulvalene host allowed switching between two host-guest binding modes in a supramolecular complex. Complexes of β-cyclodextrin with [B12F12](2-) show remarkable stability in the gas phase and were successfully tested as carriers for the delivery of boron clusters into cancer cells. PMID:27087168

  12. Binding of fluorescent lanthanides to rat liver mitochondrial membranes and calcium ion-binding proteins.

    PubMed

    Mikkelsen, R B; Wallach, D F

    1976-05-21

    (1) Tb3+ binding to mitochondrial membranes can be monitored by enhanced ion fluorescence at 545 nm with excitation at 285 nm. At low protein concentrations (less than 30 mug/ml) no inner filter effects are observed. (2) This binding is localized at the external surface of the inner membrane and is unaffected by inhibitors of respiration or oxidative phosphorylation. (3) A soluble Ca2+ binding protein isolated according to Lehninger, A.L. ((1971) Biochem. Biophys. Res. Commun. 42, 312-317) also binds Tb3+ with enhanced ion fluorescence upon excitation at 285 nm. The excitation spectrum of the isolated protein and of the intact mitochondria are indicative of an aromatic amino acid at the cation binding site. (4) Further characterization of the Tb3+-protein interaction revealed that there is more than one binding site per protein molecule and that these sites are clustered (less than 20 A). Neuraminidase treatment or organic solvent extraction of the protein did not affect fluorescent Tb3+ binding. (5) pH dependency studies of Tb3+ binding to the isolated protein or intact mitochondria demonstrated the importance of an ionizable group of pK greater than 6. At pH less than 7.5 the amount of Tb3+ bound to the isolated protein decreased with increase in pH as monitored by Tb3+ fluorescence. With intact mitochondria the opposite occurred with a large increase in Tb3+ fluorescence at higher pH. This increase was not observed when the mitochondria were preincubated with antimycin A and rotenone. PMID:6061

  13. Chloramphenicol binding to human serum albumin: Determination of binding constants and binding sites by steady-state fluorescence

    NASA Astrophysics Data System (ADS)

    Ding, Fei; Zhao, Guangyu; Chen, Shoucong; Liu, Feng; Sun, Ying; Zhang, Li

    2009-07-01

    The interaction between chloramphenicol and human serum albumin (HSA) was studied by fluorescence, UV/vis, circular dichroism (CD) and three-dimensional fluorescence spectroscopy. Fluorescence data revealed that the fluorescence quenching of HSA by chloramphenicol was the result of the formation of drug-HSA complex, and the effective quenching constants ( Ka) were 2.852 × 10 4, 2.765 × 10 4, 2.638 × 10 4 and 2.542 × 10 4 M -1 at 287, 295, 303 and 311 K, respectively. The thermodynamic parameters, enthalpy change (Δ H) and entropy change (Δ S) for the reaction were calculated to be -3.634 kJ mol -1 and 72.66 J mol -1 K -1 according to van't Hoff equation. The results indicated that the hydrophobic and electrostatic interactions played a major role in the binding of drug to HSA. The distance r between donor and acceptor was obtained to be 3.63 nm according to Förster's theory. Site marker competitive experiments indicated that the binding of drug to HSA primarily took place in subdomain IIA. The alterations of HSA secondary structure in the presence of chloramphenicol were confirmed by the evidences from synchronous fluorescence, CD and three-dimensional fluorescence spectra. In addition, the effect of common ions on the binding constants of drug-HSA complex was also discussed.

  14. Biogenic and synthetic polyamines bind cationic dendrimers.

    PubMed

    Mandeville, Jean-Sebastian; Bourassa, Phillipe; Thomas, Thekkumkattil John; Tajmir-Riahi, Heidar-Ali

    2012-01-01

    Biogenic polyamines are essential for cell growth and differentiation, while polyamine analogues exert antitumor activity in multiple experimental model systems, including breast and lung cancer. Dendrimers are widely used for drug delivery in vitro and in vivo. We report the bindings of biogenic polyamines, spermine (spm), and spermidine (spmd), and their synthetic analogues, 3,7,11,15-tetrazaheptadecane.4HCl (BE-333) and 3,7,11,15,19-pentazahenicosane.5HCl (BE-3333) to dendrimers of different compositions, mPEG-PAMAM (G3), mPEG-PAMAM (G4) and PAMAM (G4). FTIR and UV-visible spectroscopic methods as well as molecular modeling were used to analyze polyamine binding mode, the binding constant and the effects of polyamine complexation on dendrimer stability and conformation. Structural analysis showed that polyamines bound dendrimers through both hydrophobic and hydrophilic contacts with overall binding constants of K(spm-mPEG-G3) = 7.6 × 10(4) M(-1), K(spm-mPEG-PAMAM-G4) = 4.6 × 10(4) M(-1), K(spm-PAMAM-G4) = 6.6 × 10(4) M(-1), K(spmd-mPEG-G3) = 1.0 × 10(5) M(-1), K(spmd-mPEG-PAMAM-G4) = 5.5 × 10(4) M(-1), K(spmd-PAMAM-G4) = 9.2 × 10(4) M(-1), K(BE-333-mPEG-G3) = 4.2 × 10(4) M(-1), K(Be-333-mPEG-PAMAM-G4) = 3.2 × 10(4) M(-1), K(BE-333-PAMAM-G4) = 3.6 × 10(4) M(-1), K(BE-3333-mPEG-G3) = 2.2 × 10(4) M(-1), K(Be-3333-mPEG-PAMAM-G4) = 2.4 × 10(4) M(-1), K(BE-3333-PAMAM-G4) = 2.3 × 10(4) M(-1). Biogenic polyamines showed stronger affinity toward dendrimers than those of synthetic polyamines, while weaker interaction was observed as polyamine cationic charges increased. The free binding energies calculated from docking studies were: -3.2 (spermine), -3.5 (spermidine) and -3.03 (BE-3333) kcal/mol, with the following order of binding affinity: spermidine-PAMAM-G-4>spermine-PAMMAM-G4>BE-3333-PAMAM-G4 consistent with spectroscopic data. Our results suggest that dendrimers can act as carrier vehicles for delivering antitumor polyamine analogues to target tissues

  15. Binding of TATA Binding Protein to a Naturally Positioned Nucleosome Is Facilitated by Histone Acetylation

    PubMed Central

    Sewack, Gerald F.; Ellis, Thomas W.; Hansen, Ulla

    2001-01-01

    The TATA sequence of the human, estrogen-responsive pS2 promoter is complexed in vivo with a rotationally and translationally positioned nucleosome (NUC T). Using a chromatin immunoprecipitation assay, we demonstrate that TATA binding protein (TBP) does not detectably interact with this genomic binding site in MCF-7 cells in the absence of transcriptional stimuli. Estrogen stimulation of these cells results in hyperacetylation of both histones H3 and H4 within the pS2 chromatin encompassing NUC T and the TATA sequence. Concurrently, TBP becomes associated with the pS2 promoter region. The relationship between histone hyperacetylation and the binding of TBP was assayed in vitro using an in vivo-assembled nucleosomal array over the pS2 promoter. With chromatin in its basal state, the binding of TBP to the pS2 TATA sequence at the edge of NUC T was severely restricted, consistent with our in vivo data. Acetylation of the core histones facilitated the binding of TBP to this nucleosomal TATA sequence. Therefore, we demonstrate that one specific, functional consequence of induced histone acetylation at a native promoter is the alleviation of nucleosome-mediated repression of the binding of TBP. Our data support a fundamental role for histone acetylation at genomic promoters in transcriptional activation by nuclear receptors and provide a general mechanism for rapid and reversible transcriptional activation from a chromatin template. PMID:11158325

  16. How Does Confinement Change Ligand-Receptor Binding Equilibrium? Protein Binding in Nanopores and Nanochannels.

    PubMed

    Tagliazucchi, Mario; Szleifer, Igal

    2015-10-01

    We present systematic studies for the binding of small model proteins to ligands attached to the inner walls of long nanochannels and short nanopores by polymeric tethers. Binding of proteins to specific ligands inside nanometric channels and pores leads to changes in their ionic conductance, which have been exploited in sensors that quantify the concentration of the proteins in solution. The theoretical predictions presented in this work are aimed to provide a fundamental understanding of protein binding under geometrically confined environments and to guide the design of this kind of nanochannel-based sensors. The theory predicts that the fraction of the channel volume filled by bound proteins is a nonmonotonic function of the channel radius, the length of the tethers, the surface density of the ligands and the size of the proteins. Notably, increasing the density of ligands, decreasing the size of the channel or increasing the size of the protein may lead to a decrease of the fraction of the channel volume filled by bound proteins. These results are explained from the incomplete binding of proteins to the ligands due to repulsive protein-protein and protein-ligand steric interactions. Our work suggests strategies to optimize the change in conductance due to protein binding, for example: (i) proteins much smaller than the radius of the channel may effectively block the channel if tethers of appropriate length are used, and (ii) a large decrease in conductance upon protein binding can be achieved if the channel and the protein are oppositely charged. PMID:26368839

  17. Being a binding site: characterizing residue composition of binding sites on proteins.

    PubMed

    Iván, Gábor; Szabadka, Zoltán; Grolmusz, Vince

    2007-01-01

    The Protein Data Bank contains the description of more than 45,000 three-dimensional protein and nucleic-acid structures today. Started to exist as the computer-readable depository of crystallographic data complementing printed articles, the proper interpretation of the content of the individual files in the PDB still frequently needs the detailed information found in the citing publication. This fact implies that the fully automatic processing of the whole PDB is a very hard task. We first cleaned and re-structured the PDB data, then analyzed the residue composition of the binding sites in the whole PDB for frequency and for hidden association rules. Main results of the paper: (i) the cleaning and repairing algorithm (ii) redundancy elimination from the data (iii) application of association rule mining to the cleaned non-redundant data set. We have found numerous significant relations of the residue-composition of the ligand binding sites on protein surfaces, summarized in two figures. One of the classical data-mining methods for exploring implication-rules, the association-rule mining, is capable to find previously unknown residue-set preferences of bind ligands on protein surfaces. Since protein-ligand binding is a key step in enzymatic mechanisms and in drug discovery, these uncovered preferences in the study of more than 19,500 binding sites may help in identifying new binding protein-ligand pairs. PMID:18305831

  18. Granzyme A binding to target cell proteins. Granzyme A binds to and cleaves nucleolin in vitro.

    PubMed

    Pasternack, M S; Bleier, K J; McInerney, T N

    1991-08-01

    The physiologic substrates of cytotoxic T lymphocyte granule-associated serine esterases (referred to hereafter as proteases or "granzymes"), and the role of these enzymes in cell-mediated activity remain unclear. We have developed an assay for possible ligands of the trypsin-like dimeric serine protease granzyme A based on Western immunoblotting techniques. This protein-binding assay demonstrates the selective binding of granzyme A to several proteins present in the target cell P815. The binding specificity is preserved when enzyme binding is performed in the presence of excess competing proteins, including such cationic species as lysozyme and RNase. Enzyme binding is inhibited, however, by heat or detergent inactivation of granzyme A. Subcellular fractionation of target cells shows that the nuclear fraction contains most granzyme A binding reactivity, which is recovered in the nuclear salt wash fraction. A protein with Mr = 100,000 and two closely migrating proteins with Mr = 35,000 and 38,000 are the predominant reactive moieties, and the N-terminal sequence of the 100-kDa protein confirmed that this protein was murine nucleolin. Incubation of granzyme A with nucleolin generates a discrete proteolytic cleavage product of Mr = 88,000. Since nucleolin is known to shuttle between nucleus and cytoplasm, the interaction of granzyme A and nucleolin may be important in the process of apoptosis which accompanies cytotoxic T lymphocyte-mediated lysis of target cells. PMID:1860869

  19. Amphetamine binding to synthetic melanin and scatchard analysis of binding data.

    PubMed

    Gautam, Lata; Scott, Karen S; Cole, Michael D

    2005-01-01

    Previous research into drug-hair binding shows that hair color affects drug-hair binding. There are no structural disparities in hair of different colors other than the type and content of melanin present. For this reason, this investigation focuses on synthetic eumelanin as a site for drug interaction using amphetamine as the candidate drug. The binding study was carried out at room temperature. The interaction between synthetic eumelanin and amphetamine was monitored using UV-Vis spectrophotometry at 257.2 nm. As the molecular weight of melanin is unknown, the number of binding sites could not be calculated directly. Hence the ratio of the number of mumoles of drug bound and the dry weight of melanin in mug was considered. Equilibrium was reached when approximately 32% of the drug was bound to melanin. Hence this study proves that amphetamine binds to synthetic eumelanin in vitro. Data interpretation using Scatchard analysis yielded a curvilinear plot with upward concavity indicating multiple binding sites on melanin and negative cooperativity. PMID:16105258

  20. CLIPZ: a database and analysis environment for experimentally determined binding sites of RNA-binding proteins

    PubMed Central

    Khorshid, Mohsen; Rodak, Christoph; Zavolan, Mihaela

    2011-01-01

    The stability, localization and translation rate of mRNAs are regulated by a multitude of RNA-binding proteins (RBPs) that find their targets directly or with the help of guide RNAs. Among the experimental methods for mapping RBP binding sites, cross-linking and immunoprecipitation (CLIP) coupled with deep sequencing provides transcriptome-wide coverage as well as high resolution. However, partly due to their vast volume, the data that were so far generated in CLIP experiments have not been put in a form that enables fast and interactive exploration of binding sites. To address this need, we have developed the CLIPZ database and analysis environment. Binding site data for RBPs such as Argonaute 1-4, Insulin-like growth factor II mRNA-binding protein 1-3, TNRC6 proteins A-C, Pumilio 2, Quaking and Polypyrimidine tract binding protein can be visualized at the level of the genome and of individual transcripts. Individual users can upload their own sequence data sets while being able to limit the access to these data to specific users, and analyses of the public and private data sets can be performed interactively. CLIPZ, available at http://www.clipz.unibas.ch, aims to provide an open access repository of information for post-transcriptional regulatory elements. PMID:21087992

  1. Mapping the Ligand-Binding Region of Borrelia hermsii Fibronectin-Binding Protein

    PubMed Central

    Brenner, Christiane; Bomans, Katharina; Habicht, Jüri; Simon, Markus M.; Wallich, Reinhard

    2013-01-01

    Many pathogenic microorganisms express fibronectin-binding molecules that facilitate their adherence to the extracellular matrix and/or entry into mammalian cells. We have previously described a Borrelia recurrentis gene, cihC that encodes a 40-kDa surface receptor for both, fibronectin and the complement inhibitors C4bp and C1-Inh. We now provide evidence for the expression of a group of highly homologues surface proteins, termed FbpA, in three B. hermsii isolates and two tick-borne relapsing fever spirochetes, B. parkeri and B. turicatae. When expressed in Escherichia coli or B. burgdorferi, four out of five proteins were shown to selectively bind fibronectin, whereas none of five proteins were able to bind the human complement regulators, C4bp and C1-Inh. By applying deletion mutants of the B. hermsii fibronectin-binding proteins a putative high-affinity binding site for fibronectin was mapped to its central region. In addition, the fibronectin-binding proteins of B. hermsii were found to share sequence homology with BBK32 of the Lyme disease spirochete B. burgdorferi with similar function suggesting its involvement in persistence and/or virulence of relapsing fever spirochetes. PMID:23658828

  2. Sequence similarity between the erythrocyte binding domain of the Plasmodium vivax Duffy binding protein and the V3 loop of HIV-1 strain MN reveals a functional heparin binding motif involved in binding to the Duffy antigen receptor for chemokines

    PubMed Central

    2011-01-01

    Background The HIV surface glycoprotein gp120 (SU, gp120) and the Plasmodium vivax Duffy binding protein (PvDBP) bind to chemokine receptors during infection and have a site of amino acid sequence similarity in their binding domains that often includes a heparin binding motif (HBM). Infection by either pathogen has been found to be inhibited by polyanions. Results Specific polyanions that inhibit HIV infection and bind to the V3 loop of X4 strains also inhibited DBP-mediated infection of erythrocytes and DBP binding to the Duffy Antigen Receptor for Chemokines (DARC). A peptide including the HBM of PvDBP had similar affinity for heparin as RANTES and V3 loop peptides, and could be specifically inhibited from heparin binding by the same polyanions that inhibit DBP binding to DARC. However, some V3 peptides can competitively inhibit RANTES binding to heparin, but not the PvDBP HBM peptide. Three other members of the DBP family have an HBM sequence that is necessary for erythrocyte binding, however only the protein which binds to DARC, the P. knowlesi alpha protein, is inhibited by heparin from binding to erythrocytes. Heparitinase digestion does not affect the binding of DBP to erythrocytes. Conclusion The HBMs of DBPs that bind to DARC have similar heparin binding affinities as some V3 loop peptides and chemokines, are responsible for specific sulfated polysaccharide inhibition of parasite binding and invasion of red blood cells, and are more likely to bind to negative charges on the receptor than cell surface glycosaminoglycans. PMID:22122911

  3. Simultaneous optimal experimental design for in vitro binding parameter estimation.

    PubMed

    Ernest, C Steven; Karlsson, Mats O; Hooker, Andrew C

    2013-10-01

    Simultaneous optimization of in vitro ligand binding studies using an optimal design software package that can incorporate multiple design variables through non-linear mixed effect models and provide a general optimized design regardless of the binding site capacity and relative binding rates for a two binding system. Experimental design optimization was employed with D- and ED-optimality using PopED 2.8 including commonly encountered factors during experimentation (residual error, between experiment variability and non-specific binding) for in vitro ligand binding experiments: association, dissociation, equilibrium and non-specific binding experiments. Moreover, a method for optimizing several design parameters (ligand concentrations, measurement times and total number of samples) was examined. With changes in relative binding site density and relative binding rates, different measurement times and ligand concentrations were needed to provide precise estimation of binding parameters. However, using optimized design variables, significant reductions in number of samples provided as good or better precision of the parameter estimates compared to the original extensive sampling design. Employing ED-optimality led to a general experimental design regardless of the relative binding site density and relative binding rates. Precision of the parameter estimates were as good as the extensive sampling design for most parameters and better for the poorly estimated parameters. Optimized designs for in vitro ligand binding studies provided robust parameter estimation while allowing more efficient and cost effective experimentation by reducing the measurement times and separate ligand concentrations required and in some cases, the total number of samples. PMID:23943088

  4. A thermodynamic signature for drug-DNA binding mode.

    PubMed

    Chaires, Jonathan B

    2006-09-01

    A number of small molecules bind directly and selectively to DNA, acting as chemotherapeutic agents by inhibiting replication, transcription or topoisomerase activity. Two common binding modes for these small molecules are intercalation or groove-binding. Intercalation results from insertion of a planar aromatic substituent between DNA base pairs, with concomitant unwinding and lengthening of the DNA helix. Groove binding, in contrast, does not perturb the duplex structure to any great extent. Groove-binders are typically crescent-shaped, and fit snugly into the minor groove with little distortion of the DNA structure. Recent calorimetric studies have determined the enthalpic and entropic contributions to the DNA binding of representative DNA binding compounds. Analysis of such thermodynamic data culled from the literature reveals distinctive thermodynamic signatures for groove-binding and intercalating compounds. Plots of the binding enthalpy (DeltaH) against binding entropy (-TDeltaS) for 26 drug-DNA interactions reveal that groove-binding interactions are clustered in a region of the graph with favorable entropy contributions to the free energy, while intercalators are clustered in a region with unfavorable entropy but favorable enthalpy contributions. Groove-binding is predominantly entropically driven, while intercalation in enthalpically driven. The molecular basis of the contrasting thermodynamic signatures for the two binding modes is by no means clear, but the pattern should be of use in categorizing new DNA binding agents. PMID:16730635

  5. Copper binding in the prion protein.

    PubMed

    Millhauser, Glenn L

    2004-02-01

    A conformational change of the prion protein is responsible for a class of neurodegenerative diseases called the transmissible spongiform encephalopathies that include mad cow disease and the human afflictions kuru and Creutzfeldt-Jakob disease. Despite the attention given to these diseases, the normal function of the prion protein in healthy tissue is unknown. Research over the past few years, however, demonstrates that the prion protein is a copper binding protein with high selectivity for Cu(2+). The structural features of the Cu(2+) binding sites have now been characterized and are providing important clues about the normal function of the prion protein and perhaps how metals or loss of protein function play a role in disease. The link between prion protein and copper may provide insight into the general, and recently appreciated, role of metals in neurodegenerative disease. PMID:14967054

  6. Competitive protein binding assay for piritrexim

    SciTech Connect

    Woolley, J.L. Jr.; Ringstad, J.L.; Sigel, C.W. )

    1989-09-01

    A competitive protein binding assay for piritrexim (PTX, 1) that makes use of a commercially available radioassay kit for methotrexate has been developed. After it is selectively extracted from plasma, PTX competes with ({sup 125}I)methotrexate for binding to dihydrofolate reductase isolated from Lactobacillus casei. Free drug is separated from bound drug by adsorption to dextran-coated charcoal. Piritrexim is measurable over a range of 0.01 to 10.0 micrograms/mL in plasma with a coefficient of variation less than 15%. The limit of sensitivity of the assay is approximately 2 ng/mL. An excellent correlation between this assay and a previously published HPLC method was found.

  7. The Sunscreen Octyl Methoxycinnamate Binds to DNA

    NASA Astrophysics Data System (ADS)

    Norrell, Johannes; Vohra, Shikhar; Nordlund, T. M.

    2000-03-01

    Sunscreens are designed to prevent skin cancer by absorbing ultraviolet radiation from the sun before it gets to the DNA in skin cells. The purpose of this work is to determine whether or not octyl methoxycinnamate, an active ingredient in many sunscreens, will bind to DNA. If so, the sunscreen could transfer the energy it absorbed from the sun to the DNA and cause damage. To determine this, we prepared samples with varying concentrations of cinnamate added to herring sperm DNA, sonicating the mixture to disperse the hydrophobic sunscreen into solution. Absorption and fluorescence spectra of the mixtures showed (i) much more sunscreen was dispersed into solution when DNA was present, and (ii) the spectra of both DNA and sunscreen differed from those of the separate solutions. We conclude that the octyl methoxycinnamate can indeed bind to DNA in aqueous solution. Energy transfer experiments from DNA to sunscreen and from sunscreen to 2-aminopurine- (a fluorescent DNA base) labeled DNA will be presented.

  8. Triazatriangulene as binding group for molecular electronics.

    PubMed

    Wei, Zhongming; Wang, Xintai; Borges, Anders; Santella, Marco; Li, Tao; Sørensen, Jakob Kryger; Vanin, Marco; Hu, Wenping; Liu, Yunqi; Ulstrup, Jens; Solomon, Gemma C; Chi, Qijin; Bjørnholm, Thomas; Nørgaard, Kasper; Laursen, Bo W

    2014-12-16

    The triazatriangulene (TATA) ring system was investigated as a binding group for tunnel junctions of molecular wires on gold surfaces. Self-assembled monolayers (SAMs) of TATA platforms with three different lengths of phenylene wires were fabricated, and their electrical conductance was recorded by both conducting probe-atomic force microscopy (CP-AFM) and scanning tunneling microscopy (STM). Similar measurements were performed for phenylene SAMs with thiol anchoring groups as references. It was found that, despite the presence of a sp(3) hybridized carbon atom in the conduction path, the TATA platform displays a contact resistance only slightly larger than the thiols. This surprising finding has not been reported before and was analyzed by theoretical computations of the transmission functions of the TATA anchored molecular wires. The relatively low contact resistance of the TATA platform along with its high stability and directionality make this binding group very attractive for molecular electronic measurements and devices. PMID:25426950

  9. Programmable DNA-binding Small Molecules

    PubMed Central

    Blackledge, Meghan S.; Melander, Christian

    2013-01-01

    Aberrant gene expression is responsible for a myriad of human diseases from infectious diseases to cancer. Precise regulation of these genes via specific interactions with the DNA double helix could pave the way for novel therapeutics. Pyrrole-imidazole polyamides are small molecules capable of binding to pre-determined DNA sequences up to 16 base pairs with affinity and specificity comparable to natural transcription factors. In the three decades since their development, great strides have been made relating to synthetic accessibility and improved sequence specificity and binding affinity. This perspective presents a brief history of early seminal developments in the field and highlights recent reports of the utility of polyamides as both genetic modulators and molecular probes. PMID:23665141

  10. Odorant-binding proteins in insects.

    PubMed

    Zhou, Jing-Jiang

    2010-01-01

    Our understanding of the molecular and biochemical mechanisms that mediate chemoreception in insects has been greatly improved after the discovery of olfactory and taste receptor proteins. However, after 50 years of the discovery of first insect sex pheromone from the silkmoth Bombyx mori, it is still unclear how hydrophobic compounds reach the dendrites of sensory neurons in vivo across aqueous space and interact with the sensory receptors. The presence of soluble polypeptides in high concentration in the lymph of chemosensilla still poses unanswered questions. More than two decades after their discovery and despite the wealth of structural and biochemical information available, the physiological function of odorant-binding proteins (OBPs) is not well understood. Here, I review the structural properties of different subclasses of insect OBPs and their binding to pheromones and other small ligands. Finally, I discuss current ideas and models on the role of such proteins in insect chemoreception. PMID:20831949

  11. Quantifying drug-protein binding in vivo.

    SciTech Connect

    Buchholz, B; Bench, G; Keating III, G; Palmblad, M; Vogel, J; Grant, P G; Hillegonds, D

    2004-02-17

    Accelerator mass spectrometry (AMS) provides precise quantitation of isotope labeled compounds that are bound to biological macromolecules such as DNA or proteins. The sensitivity is high enough to allow for sub-pharmacological (''micro-'') dosing to determine macromolecular targets without inducing toxicities or altering the system under study, whether it is healthy or diseased. We demonstrated an application of AMS in quantifying the physiologic effects of one dosed chemical compound upon the binding level of another compound in vivo at sub-toxic doses [4].We are using tissues left from this study to develop protocols for quantifying specific binding to isolated and identified proteins. We also developed a new technique to quantify nanogram to milligram amounts of isolated protein at precisions that are comparable to those for quantifying the bound compound by AMS.

  12. Preferred Metal Binding Site of Aniline

    NASA Astrophysics Data System (ADS)

    Kumari, Sudesh; Sohnlein, Brad; Yang, Dong-Sheng

    2012-06-01

    Group III metal-aniline complexes, M-aniline (M = Sc, Y, and La), were produced by interactions between laser-vaporized metal atoms and aniline vapor in a pulsed molecular beam source, identified by photoionization time-of-flight mass spectrometry, and studied by pulsed-field ionization zero electron kinetic energy (ZEKE) spectroscopy and density functional theory calculations. Adiabatic ionization energies and several vibrational intervals were measured from the ZEKE spectra. Metal binding sites and electronic states were determined by combining the ZEKE measurements and theoretical calculations. Although aniline has various possible sites for metal coordination, the preferred site was determined to be phenyl ring. The metal binding with the phenyl ring yields syn and anti conformers. In these conformers, the neutral complexes are in doublet ground states and the corresponding singly charged cations in singlet states.

  13. DNA Triplexes That Bind Several Cofactor Molecules.

    PubMed

    Vollmer, Sven; Richert, Clemens

    2015-12-14

    Invited for the cover of this issue are Sven Vollmer and Clemens Richert of the University of Stuttgart. The cover image hints at the analogy between a honey comb, as a macroscopic storage device, and DNA triplexes with designed binding sites, as molecular storage motifs that can release ATP to fuel a bioluminescence reaction. Read the full text of the article at 10.1002/chem.201503220. PMID:26534779

  14. Cadmium-binding protein (metallothionein) in carp.

    PubMed Central

    Kito, H; Ose, Y; Sato, T

    1986-01-01

    When carp (Cyprinus carpio) were exposed to 5 and 30 ppm Cd in the water, the contents of Cd-binding protein, which has low molecular weight, increased in the hepatopancreas, kidney, gills and gastrointestinal tract with the duration of exposure. This Cd-binding protein was purified from hepatopancreas, kidney, gills, and spleen of carp administered 2 mg/kg Cd (as CdCl2), intraperitoneally for 6 days. Two Cd-binding proteins were separated by DEAE-Sephadex A-25 column chromatography. These proteins had Cd-mercaptide bond, high cysteine contents (ca. 29-34%), but no aromatic amino acids or histidine. From these characteristics the Cd-binding proteins were identified as metallothionein. By using antiserum obtained from a rabbit to which carp hepatopancreas MT-II had been administered, immunological characteristics between hepatopancreas MT-I, II and kidney MT-II were studied, and a slight difference in antigenic determinant was observed among them. By immunological staining techniques with horseradish peroxidase, the localization of metallothionein was investigated. In the nontreated group, metallothionein was present in the acinar cells of hepatopancreas and renal convoluted tubules. In the Cd-treated group (2 mg/kg IP daily for 3 days), metallothionein was present in the nuclei, sinusoids, and extracellular space of hepatopancreas, in addition to the acinar cells. Carp were bred in 1 ppm Cd, 5 ppm Zn solution, and tap water for 14 days, following transfer to 15 ppm Cd solution, respectively. The survival ratio was the highest in the Zn group followed by Cd-treated and control groups. The metallothionein contents increased in hepatopancreas and kidney in the order: Zn greater than Cd greater than control group. Images FIGURE 5. FIGURE 6. PMID:3519201

  15. Tight Binding Models in Cold Atoms Physics

    NASA Astrophysics Data System (ADS)

    Zakrzewski, J.

    2007-05-01

    Cold atomic gases placed in optical lattice potentials offer a unique tool to study simple tight binding models. Both the standard cases known from the condensed matter theory as well as novel situations may be addressed. Cold atoms setting allows for a precise control of parameters of the systems discussed, stimulating new questions and problems. The attempts to treat disorder in a controlled fashion are addressed in detail.

  16. Gene encoding herbicide safener binding protein

    SciTech Connect

    Walton, J.D.; Scott-Craig, J.S.

    1999-10-26

    The cDNA encoding safener binding protein (SafBP), also referred to as SBP1, is presented. The deduced amino acid sequence is provided. Methods of making and using SBP1 and SafBP to alter a plant's sensitivity to certain herbicides or a plant's responsiveness to certain safeners are also provided, as well as expression vectors, transgenic plants or other organisms transfected with vectors and seeds from the plants.

  17. Shiga toxin binds to activated platelets.

    PubMed

    Ghosh, S A; Polanowska-Grabowska, R K; Fujii, J; Obrig, T; Gear, A R L

    2004-03-01

    Hemolytic uremic syndrome (HUS) is associated with acute renal failure in children and can be caused by Shiga toxin (Stx)-producing Escherichia coli. Thrombocytopenia and formation of renal thrombi are characteristic of HUS, suggesting that platelet activation is involved in its pathogenesis. However, whether Shiga toxin directly activates platelets is controversial. The present study evaluates if potential platelet sensitization during isolation by different procedures influences platelet interaction with Shiga toxin. Platelets isolated from sodium citrate anticoagulated blood were exposed during washing to EDTA and higher g forces than platelets prepared from acid-citrate-dextrose (ACD) plasma. Platelet binding of Stx was significantly higher in EDTA-washed preparations relative to ACD-derived platelets. Binding of Stx was also increased with ACD-derived platelets when activated with thrombin (1 U mL-1) and exposure of the Gb3 Stx receptor was detected only on platelets subjected to EDTA, higher g forces or thrombin. EDTA-exposed platelets lost their normal discoid shape and were larger. P-selectin (CD62P) exposure was significantly increased in EDTA-washed preparations relative to ACD-derived platelets, suggesting platelet activation. Taken together, these results suggest that direct binding of Stx occurs only on 'activated' platelets rather than on resting platelets. The ability of Stx to interact with previously activated platelets may be an important element in understanding the pathogenesis of HUS. PMID:15009469

  18. Cellulose-binding domains: biotechnological applications.

    PubMed

    Levy, Ilan; Shoseyov, Oded

    2002-11-01

    Many researchers have acknowledged the fact that there exists an immense potential for the application of the cellulose-binding domains (CBDs) in the field of biotechnology. This becomes apparent when the phrase "cellulose-binding domain" is used as the key word for a computerized patent search; more then 150 hits are retrieved. Cellulose is an ideal matrix for large-scale affinity purification procedures. This chemically inert matrix has excellent physical properties as well as low affinity for nonspecific protein binding. It is available in a diverse range of forms and sizes, is pharmaceutically safe, and relatively inexpensive. Present studies into the application of CBDs in industry have established that they can be applied in the modification of physical and chemical properties of composite materials and the development of modified materials with improved properties. In agro-biotechnology, CBDs can be used to modify polysaccharide materials both in vivo and in vitro. The CBDs exert nonhydrolytic fiber disruption on cellulose-containing materials. The potential applications of "CBD technology" range from modulating the architecture of individual cells to the modification of an entire organism. Expressing these genes under specific promoters and using appropriate trafficking signals, can be used to alter the nutritional value and texture of agricultural crops and their final products. PMID:14550028

  19. The aesthetic experience of 'contour binding'.

    PubMed

    Casco, Clara; Guzzon, Daniela

    2008-01-01

    To find the diagnostic spatial frequency information in different painting styles (cubism, impressionism and realism), we have compared sensitivity (d') in distinguishing signal (subject of the painting) from noise with normal, high-pass and low-pass filtered images at long (150 ms) and short (30 ms) exposure. We found that for cubist-style images, d' increases with high-pass filtering compared with normal and low-pass filtered images, but decreases with low-pass filtering compared with normal images. These results indicate that channels with high spatial resolution provide the diagnostic information to solve the binding problem. Sensitivity for images in impressionist style was instead reduced by both low- and high-pass filtering. This indicates that both high and low spatial frequency channels play a role in solving the binding problem, suggesting the involvement of large collator units that group the response of small channels tuned to the same orientation. The difference between realism, which shows higher sensitivity for low-frequency filtering at short durations and cubism in which the binding problem is solved by high spatial frequency channels, has a corresponding difference in aesthetic judgment: the probability of judging a painting as 'intriguing' is larger with low-pass filtering than with high-pass filtering in realism, while the opposite is true for cubism. This suggests that the aesthetic experience is available during early processing of an image, and could preferentially influence high-level categorization of the subject of a painting. PMID:18534105

  20. Cooperative substrate binding by a diguanylate cyclase.

    PubMed

    Oliveira, Maycon C; Teixeira, Raphael D; Andrade, Maxuel O; Pinheiro, Glaucia M S; Ramos, Carlos H I; Farah, Chuck S

    2015-01-30

    XAC0610, from Xanthomonas citri subsp. citri, is a large multi-domain protein containing one GAF (cGMP-specific phosphodiesterases, adenylyl cyclases and FhlA) domain, four PAS (Per-Arnt-Sim) domains and one GGDEF domain. This protein has a demonstrable in vivo and in vitro diguanylate cyclase (DGC) activity that leads to the production of cyclic di-GMP (c-di-GMP), a ubiquitous bacterial signaling molecule. Analysis of a XacΔ0610 knockout strain revealed that XAC0610 plays a role in the regulation of Xac motility and resistance to H2O2. Site-directed mutagenesis of a conserved DGC lysine residue (Lys759 in XAC0610) resulted in a severe reduction in XAC0610 DGC activity. Furthermore, experimental and in silico analyses suggest that XAC0610 is not subject to allosteric product inhibition, a common regulatory mechanism for DGC activity control. Instead, steady-state kinetics of XAC0610 DGC activity revealed a positive cooperative effect of the GTP substrate with a dissociation constant for the binding of the first GTP molecule (K1) approximately 5× greater than the dissociation constant for the binding of the second GTP molecule (K2). We present a general kinetics scheme that should be used when analyzing DGC kinetics data and propose that cooperative GTP binding could be a common, though up to now overlooked, feature of these enzymes that may in some cases offer a physiologically relevant mechanism for regulation of DGC activity in vivo. PMID:25463434