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Exploiting Chemical Protein Synthesis to Study the Role of Tyrosine Sulfation on Anticoagulants from Hematophagous Organisms. Acc Chem Res 2023; 56:2688-2699. [PMID: 37708351 DOI: 10.1021/acs.accounts.3c00388] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/16/2023]
Abstract
Tyrosine sulfation is a post-translational modification (PTM) that modulates function by mediating key protein-protein interactions. One of the early proteins shown to possess this PTM was hirudin, produced in the salivary glands of the medicinal leech Hirudo medicinalis, whereby tyrosine sulfation led to a ∼10-fold improvement in α-thrombin inhibitory activity. Outside of this pioneering discovery, the involvement of tyrosine sulfation in modulating the activity of salivary proteins from other hematophagous organisms was unknown. We hypothesized that the intrinsic instability of the tyrosine sulfate functionality, particularly under the acidic conditions used to isolate and analyze peptides and proteins, has led to poor detection during the isolation and/or expression of these molecules.Herein, we summarize our efforts to interrogate the functional role of tyrosine sulfation in the thrombin inhibitory and anticoagulant activity of salivary peptides and proteins from a range of different blood feeding organisms, including leeches, ticks, mosquitoes, and flies. Specifically, we have harnessed synthetic chemistry to efficiently generate homogeneously sulfated peptides and proteins for detailed structure-function studies both in vitro and in vivo.Our studies began with the leech protein hirudin P6 (from Hirudinaria manillensis), which is both sulfated on tyrosine and O-glycosylated at a nearby threonine residue. Synthetically, this was achieved through solid-phase peptide synthesis (SPPS) with a late-stage on-resin sulfation, followed by native chemical ligation and a folding step to generate six differentially modified variants of hirudin P6 to assess the functional interplay between O-glycosylation and tyrosine sulfation. A one-pot, kinetically controlled ligation of three peptide fragments was used to assemble homogeneously sulfoforms of madanin-1 and chimadanin from the tick Haemaphysalis longicornis. Dual tyrosine sulfation at two distinct sites was shown to increase the thrombin inhibitory activity by up to 3 orders of magnitude through a novel interaction with exosite II of thrombin. The diselenide-selenoester ligation developed by our lab provided us with a means to rapidly assemble a library of different sulfated tick anticoagulant proteins: the andersonins, hyalomins, madanin-like proteins, and hemeathrins, thus enabling the generation of key structure-activity data on this family of proteins. We have also confirmed the presence of tyrosine sulfation in the anticoagulant proteins of Anopheles mosquitoes (anophelins) and the Tsetse fly (TTI) via insect expression and mass spectrometric analysis. These molecules were subsequently synthesized and assessed for thrombin inhibitory and anticoagulant activity. Activity was significantly improved by the addition of tyrosine sulfate modifications and led to molecules with potent antithrombotic activity in an in vivo murine thrombosis model.The Account concludes with our most recent work on the design of trivalent hybrids that tandemly occupy the active site and both exosites (I and II) of α-thrombin, with a TTI-anophelin hybrid (Ki = 20 fM against α-thrombin) being one of the most potent protease inhibitors and anticoagulants ever generated. Taken together, this Account highlights the importance of the tyrosine sulfate post-translational modification within salivary proteins from blood feeding organisms for enhancing anticoagulant activity. This work lays the foundation for exploiting native or engineered variants as therapeutic leads for thrombotic disorders in the future.
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Site-selective photocatalytic functionalization of peptides and proteins at selenocysteine. Nat Commun 2022; 13:6885. [PMID: 36371402 PMCID: PMC9653470 DOI: 10.1038/s41467-022-34530-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Accepted: 10/27/2022] [Indexed: 11/15/2022] Open
Abstract
The importance of modified peptides and proteins for applications in drug discovery, and for illuminating biological processes at the molecular level, is fueling a demand for efficient methods that facilitate the precise modification of these biomolecules. Herein, we describe the development of a photocatalytic method for the rapid and efficient dimerization and site-specific functionalization of peptide and protein diselenides. This methodology, dubbed the photocatalytic diselenide contraction, involves irradiation at 450 nm in the presence of an iridium photocatalyst and a phosphine and results in rapid and clean conversion of diselenides to reductively stable selenoethers. A mechanism for this photocatalytic transformation is proposed, which is supported by photoluminescence spectroscopy and density functional theory calculations. The utility of the photocatalytic diselenide contraction transformation is highlighted through the dimerization of selenopeptides, and by the generation of two families of protein conjugates via the site-selective modification of calmodulin containing the 21st amino acid selenocysteine, and the C-terminal modification of a ubiquitin diselenide.
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Synthesis of Protein-Oligonucleotide Conjugates. Biomolecules 2022; 12:biom12101523. [PMID: 36291732 PMCID: PMC9599799 DOI: 10.3390/biom12101523] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 10/17/2022] [Accepted: 10/18/2022] [Indexed: 11/16/2022] Open
Abstract
Nucleic acids and proteins form two of the key classes of functional biomolecules. Through the ability to access specific protein-oligonucleotide conjugates, a broader range of functional molecules becomes accessible which leverages both the programmability and recognition potential of nucleic acids and the structural, chemical and functional diversity of proteins. Herein, we summarize the available conjugation strategies to access such chimeric molecules and highlight some key case study examples within the field to showcase the power and utility of such technology.
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Cover Picture: Optochemical Control of Therapeutic Agents through Photocatalyzed Isomerization (Angew. Chem. Int. Ed. 28/2022). Angew Chem Int Ed Engl 2022. [DOI: 10.1002/anie.202208067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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5
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Optochemical Control of Therapeutic Agents through Photocatalyzed Isomerization. Angew Chem Int Ed Engl 2022; 61:e202203390. [PMID: 35510306 PMCID: PMC9400970 DOI: 10.1002/anie.202203390] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Indexed: 12/04/2022]
Abstract
A Ru(bpy)3Cl2 photocatalyst is applied to the rapid trans to cis isomerization of a range of alkene‐containing pharmacological agents, including combretastatin A‐4 (CA‐4), a clinical candidate in oncology, and resveratrol derivatives, switching their configuration from inactive substances to potent cytotoxic agents. Selective in cellulo activation of the CA‐4 analog Res‐3M is demonstrated, along with its potent cytotoxicity and inhibition of microtubule dynamics.
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Optochemical Control of Therapeutic Agents through Photocatalyzed Isomerization. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202208067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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7
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Optochemical Control of Therapeutic Agents through Photocatalyzed Isomerization. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202203390] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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8
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Expressed Protein Selenoester Ligation. ANGEWANDTE CHEMIE (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2022; 134:e202200163. [PMID: 38505698 PMCID: PMC10947028 DOI: 10.1002/ange.202200163] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Indexed: 03/21/2024]
Abstract
Herein, we describe the development and application of a novel expressed protein selenoester ligation (EPSL) methodology for the one-pot semi-synthesis of modified proteins. EPSL harnesses the rapid kinetics of ligation reactions between modified synthetic selenopeptides and protein aryl selenoesters (generated from expressed intein fusion precursors) followed by in situ chemoselective deselenization to afford target proteins at concentrations that preclude the use of traditional ligation methods. The utility of the EPSL technology is showcased through the efficient semi-synthesis of ubiquitinated polypeptides, lipidated analogues of the membrane-associated GTPase YPT6, and site-specifically phosphorylated variants of the oligomeric chaperone protein Hsp27 at high dilution.
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Abstract
Herein, we describe the development and application of a novel expressed protein selenoester ligation (EPSL) methodology for the one‐pot semi‐synthesis of modified proteins. EPSL harnesses the rapid kinetics of ligation reactions between modified synthetic selenopeptides and protein aryl selenoesters (generated from expressed intein fusion precursors) followed by in situ chemoselective deselenization to afford target proteins at concentrations that preclude the use of traditional ligation methods. The utility of the EPSL technology is showcased through the efficient semi‐synthesis of ubiquitinated polypeptides, lipidated analogues of the membrane‐associated GTPase YPT6, and site‐specifically phosphorylated variants of the oligomeric chaperone protein Hsp27 at high dilution.
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Photocatalysis in Chemical Biology: Extending the Scope of Optochemical Control and Towards New Frontiers in Semisynthetic Bioconjugates and Biocatalysis. Helv Chim Acta 2021. [DOI: 10.1002/hlca.202100179] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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11
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Abstract
Hi1a is a venom peptide from the Australian funnel-web spider Hadronyche infensa with a complex tertiary structure. Hi1a has neuroprotective and cardioprotective properties due to its potent inhibition of acid-sensing ion channel 1a (ASIC1a) and is currently being pursued as a novel therapy for acute ischemic events. Herein, we describe the total synthesis of Hi1a using native chemical ligation. The synthetic peptide was successfully folded and exhibited similar inhibitory activity on ASIC1a to recombinant Hi1a.
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Rücktitelbild: Potent Trivalent Inhibitors of Thrombin through Hybridization of Salivary Sulfopeptides from Hematophagous Arthropods (Angew. Chem. 10/2021). Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202101236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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13
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Potent Trivalent Inhibitors of Thrombin through Hybridization of Salivary Sulfopeptides from Hematophagous Arthropods. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202015127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Potent Trivalent Inhibitors of Thrombin through Hybridization of Salivary Sulfopeptides from Hematophagous Arthropods. Angew Chem Int Ed Engl 2021; 60:5348-5356. [PMID: 33345438 DOI: 10.1002/anie.202015127] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Revised: 12/14/2020] [Indexed: 12/20/2022]
Abstract
Blood feeding arthropods, such as leeches, ticks, flies and mosquitoes, provide a privileged source of peptidic anticoagulant molecules. These primarily operate through inhibition of the central coagulation protease thrombin by binding to the active site and either exosite I or exosite II. Herein, we describe the rational design of a novel class of trivalent thrombin inhibitors that simultaneously block both exosites as well as the active site. These engineered hybrids were synthesized using tandem diselenide-selenoester ligation (DSL) and native chemical ligation (NCL) reactions in one-pot. The most potent trivalent inhibitors possessed femtomolar inhibition constants against α-thrombin and were selective over related coagulation proteases. A lead hybrid inhibitor possessed potent anticoagulant activity, blockade of both thrombin generation and platelet aggregation in vitro and efficacy in a murine thrombosis model at 1 mg kg-1 . The rational engineering approach described here lays the foundation for the development of potent and selective inhibitors for a range of other enzymatic targets that possess multiple sites for the disruption of protein-protein interactions, in addition to an active site.
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Back Cover: Potent Trivalent Inhibitors of Thrombin through Hybridization of Salivary Sulfopeptides from Hematophagous Arthropods (Angew. Chem. Int. Ed. 10/2021). Angew Chem Int Ed Engl 2021. [DOI: 10.1002/anie.202101236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Abstract
Interferon-γ (IFN-γ) is a glycoprotein that is responsible for orchestrating numerous critical immune induction and modulation processes and is used clinically for the treatment of a number of diseases. Herein, we describe the total chemical synthesis of homogeneously glycosylated variants of human IFN-γ using a tandem diselenide-selenoester ligation-deselenization strategy in the C- to N-terminal direction. The synthetic glycoproteins were successfully folded, and the structures and antiviral functions were assessed.
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Diselenide–selenoester ligation for chemical protein synthesis. Nat Protoc 2019; 14:2229-2257. [DOI: 10.1038/s41596-019-0180-4] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Accepted: 04/16/2019] [Indexed: 01/30/2023]
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Mosquito-Derived Anophelin Sulfoproteins Are Potent Antithrombotics. ACS CENTRAL SCIENCE 2018; 4:468-476. [PMID: 29721529 PMCID: PMC5920608 DOI: 10.1021/acscentsci.7b00612] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/23/2017] [Indexed: 06/08/2023]
Abstract
The anophelins are small protein thrombin inhibitors that are produced in the salivary glands of the Anopheles mosquito to fulfill a vital role in blood feeding. A bioinformatic analysis of anophelin sequences revealed the presence of conserved tyrosine residues in an acidic environment that were predicted to be post-translationally sulfated in vivo. To test this prediction, insect cell expression of two anophelin proteins, from Anopheles albimanus and Anopheles gambiae, was performed, followed by analysis by mass spectrometry, which showed heterogeneous sulfation at the predicted sites. Homogeneously sulfated variants of the two proteins were subsequently generated by chemical synthesis via a one-pot ligation-desulfurization strategy. Tyrosine sulfation of the anophelins was shown to significantly enhance the thrombin inhibitory activity, with a doubly sulfated variant of the anophelin from A. albimanus exhibiting a 100-fold increase in potency compared with the unmodified homologue. Sulfated anophelins were also shown to exhibit potent in vivo anticoagulant and antithrombotic activity.
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Solid-phase synthesis of peptide selenoesters via a side-chain anchoring strategy. Chem Commun (Camb) 2018; 53:5424-5427. [PMID: 28462972 DOI: 10.1039/c7cc00823f] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Peptide selenoesters have recently emerged as key building blocks for the ligation-based assembly of large polypeptides and proteins. Herein, we report an efficient solid-phase method for the high yielding and epimerisation-free synthesis of peptide selenoesters using a side-chain immobilisation strategy.
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Abstract
Combining modern synthetic and molecular biology toolkits, native chemical ligation and expressed protein ligation enables robust access to modified proteins.
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22
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Synthesis and evaluation of phenoxymethylbenzamide analogues as anti-trypanosomal agents. MEDCHEMCOMM 2015. [DOI: 10.1039/c4md00406j] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The synthesis of a compound library based on a high throughput screening hit led to the discovery of several potent anti-trypanosomal agents.
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Abstract
The groupings of taxa in a phylogenetic tree cannot represent all the conflicting signals that usually occur among site patterns in aligned homologous genetic sequences. Hence a tree-building program must compromise by reporting a subset of the patterns, using some discriminatory criterion. Thus, in the worst case, out of possibly a large number of equally good trees, only an arbitrarily chosen tree might be reported by the tree-building program as "The Tree." This tree might then be used as a basis for phylogenetic conclusions. One strategy to represent conflicting patterns in the data is to construct a network. The Buneman graph is a theoretically very attractive example of such a network. In particular, a characterization for when this network will be a tree is known. Also the Buneman graph contains each of the most parsimonious trees indicated by the data. In this paper we describe a new method for constructing the Buneman graph that can be used for a generalization of Hadamard conjugation to networks. This new method differs from previous methods by allowing us to focus on local regions of the graph without having to first construct the full graph. The construction is illustrated by an example.
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The AAPM/RSNA physics tutorial for residents: internal radiation dosimetry: principles and applications. Radiographics 2000; 20:533-46; quiz 531-2. [PMID: 10715348 DOI: 10.1148/radiographics.20.2.g00mc33533] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Internal dose calculations in nuclear medicine normally use the techniques, equations, and resources provided by the Medical Internal Radiation Dose (MIRD) Committee of the Society of Nuclear Medicine. The MIRD schema uses a unique set of symbols and quantities to calculate the absorbed dose of radiation in any target organ per radioactive decay in any source organ. The calculations involve the energy emitted per radioactive decay, the fraction of the emitted energy that is absorbed in various target organs, the masses of these organs, and both the physical decay and biologic clearance of the injected radioactive material. Standardized mathematical models (phantoms) of the human body and standardized biokinetic models are also used. A computer program, MIRDose, calculates dose tables per unit administered activity of various radiopharmaceuticals. Special care must be taken when nuclear medicine procedures involve pregnant or lactating patients. New methodologies are becoming available to calculate doses to individual patients.
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Stability of meperidine in an implantable infusion pump using capillary gas chromatography-mass spectrometry and a deuterated internal standard. J Pharm Biomed Anal 1999; 21:577-83. [PMID: 10701424 DOI: 10.1016/s0731-7085(99)00149-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
A capillary gas chromatographic-mass spectrometric (GC MS) method is described for the analysis of meperidine using 3,3,5,5-[2H4]-meperidine as an internal standard. Chromatography was performed on a (5% phenyl) methylpolysiloxane column (30 m x 0.32 mm I.D., 0.25 microm film thickness) operated at 195 degrees C; helium carrier gas-50 cm/s(-1), tR = 2.3 min. Ionization was by electron impact (EI) and detection by selected ion monitoring of the molecular ions. The method provided high response linearity (mean r = 0.9982) and precision (< 6.5% C.V.). Application of this method to a pilot study of aqueous meperidine x HCl (10 mg/ml(-1)) stability in a surgically implantable infusion pump at 37 degrees C for 90 days revealed no demonstrable drug degradation.
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MIRD pamphlet No. 17: the dosimetry of nonuniform activity distributions--radionuclide S values at the voxel level. Medical Internal Radiation Dose Committee. J Nucl Med 1999; 40:11S-36S. [PMID: 9935083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023] Open
Abstract
The availability of quantitative three-dimensional in vivo data on radionuclide distributions within the body makes it possible to calculate the corresponding nonuniform distribution of radiation absorbed dose in body organs and tissues. This pamphlet emphasizes the utility of the MIRD schema for such calculations through the use of radionuclide S values defined at the voxel level. The use of both dose point-kernels and Monte Carlo simulation methods is also discussed. PET and SPECT imaging can provide quantitative activity data in voxels of several millimeters on edge. For smaller voxel sizes, accurate data cannot be obtained using present imaging technology. For submillimeter dimensions, autoradiographic methods may be used when tissues are obtained through biopsy or autopsy. Sample S value tabulations for five radionuclides within cubical voxels of 3 mm and 6 mm on edge are given in the appendices to this pamphlet. These S values may be used to construct three-dimensional dose profiles for nonuniform distributions of radioactivity encountered in therapeutic and diagnostic nuclear medicine. Data are also tabulated for 131I in 0.1-mm voxels for use in autoradiography. Two examples illustrating the use of voxel S values are given, followed by a discussion of the use of three-dimensional dose distributions in understanding and predicting biologic response.
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The MIRD perspective 1999. Medical Internal Radiation Dose Committee. J Nucl Med 1999; 40:3S-10S. [PMID: 9935082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023] Open
Abstract
The MIRD schema is a general approach for medical internal radiation dosimetry. Although the schema has traditionally been used for organ dosimetry, it is also applicable to dosimetry at the suborgan, voxel, multicellular and cellular levels. The MIRD pamphlets that follow in this issue and in coming issues, as well as the recent monograph on cellular dosimetry, demonstrate the flexibility of this approach. Furthermore, these pamphlets provide new tools for radionuclide dosimetry applications, including the dynamic bladder model, S values for small structures within the brain (i.e., suborgan dosimetry), voxel S values for constructing three-dimensional dose distributions and dose-volume histograms and techniques for acquiring quantitative distribution and pharmacokinetic data.
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Abstract
This paper presents a short history of the development of medical internal dosimetry. It reviews the evolution of the equations and discusses the development of various mathematical models used to improve radiation absorbed dose estimates. The contributions of Leonidas Marinelli, Edith Quimby, William Mayneord, Robert Loevinger, Walter Snyder, and others are emphasized.
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Abstract
The MIRD scheme is not restricted to calculating mean absorbed doses in organs but can be extended to any tissue for which distribution and retention data can be obtained and for which a reasonably accurate mathematical description of the source and target tissues can be determined. The development of more accurate absorbed dose estimates and the correlation of these estimates with radiation effects will lead to a better understanding of the results from radiotherapeutic agents such as radiolabeled monoclonal antibodies. Therefore, radiobiologists and internal dosimetrists need to combine their efforts and work toward the common goal of improving the treatment of malignant diseases.
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30
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MIRD dose estimate no. 15: radiation absorbed dose estimates for radioindium-labeled autologous platelets. J Nucl Med 1992; 33:777-80. [PMID: 1569490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
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31
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Radiation dosimetry for the adult female and fetus from iodine-131 administration in hyperthyroidism. J Nucl Med 1991; 32:808-13. [PMID: 2022987] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Through a study of the iodine kinetics of 127 patients, we have developed radiation dose estimates to major organs and the fetus for patients with varying degrees of hyperthyroidism. We observed a negative correlation between maximum thyroid uptake and biologic half-time of iodine in the thyroid and used this correlation to predict the biologic half-time at fixed values of maximum thyroid uptake. Dose estimates to the bladder, gonads, marrow, thyroid, uterus, and whole body were estimated for maximum thyroid uptakes from 20% to 100%. Bladder dose varied from 0.6 to 1.0 mGy/MBq and dose to the uterus varied from 0.036 to 0.063 mGy/MBq under different model assumptions. Dose estimates to the fetus and fetal thyroid were approximated at all stages of pregnancy. Average fetal dose was a maximum between 0 and 2 mo of pregnancy, with the maximum ranging from 0.048 mGy/MBq to 0.083 mGy/MBq, depending on model assumptions. Some radiation risks for irradiation of the fetus and the fetal thyroid are discussed.
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Dosimetry of swallowed non-absorbed technetium 99m radiopharmaceuticals in paediatric patients. EUROPEAN JOURNAL OF NUCLEAR MEDICINE 1991; 18:288-92. [PMID: 2070807 DOI: 10.1007/bf00186655] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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A model of the peritoneal cavity for use in internal dosimetry. J Nucl Med 1989; 30:2002-11. [PMID: 2585102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Several therapeutic and diagnostic techniques involve injection of radioactive material into the peritoneal cavity. Estimation of the radiation dose to the surface of the peritoneum or to surrounding organs is hampered by the lack of a suitable source region in the phantom commonly used for such calculations. We have modified the Fisher-Snyder phantom to include a region representing the peritoneal cavity which may be employed to estimate such radiation doses. A geometric model is described which is coordinated with the existing organ regions in the phantom. Specific absorbed fractions (derived by Monte Carlo techniques) for photon emissions originating within the cavity are listed. Photon S-values for several radionuclides which have been administered intraperitoneally are shown. Dose conversion factors for electrons irradiating the peritoneal cavity wall, from either a thin plane or volume source of activity within the cavity, are also given for several nuclides.
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Radiation absorbed dose from technetium-99m-labeled bone imaging agents. Task Group of the Medical Internal Radiation Dose Committee, The Society of Nuclear Medicine. J Nucl Med 1989; 30:1117-22. [PMID: 2544697] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
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35
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Abstract
Biodistribution, kinetics and dosimetry of 9Tcm-albumin colloid labeled leukocytes (TAC-WBC) is described. A practical method of planar image data acquisition and processing is discussed. This method was used to obtain biodistribution data in 11 patients, two of whom were children. Dosimetry was calculated for fetuses, children and adults. The spleen is the critical organ, receiving 2.5 rad per 5 mCi procedure in adults and 3.6 rad per 2.15 mCi procedure in a 5-year-old child. These absorbed doses are about one-sixth of that absorbed from 111In-leukocytes procedures utilizing one-tenth the administered activity of TAC-WBC. The liver and red marrow are approximately equivalent secondary target organs, each receiving about 20% of the spleen dose. Fetal doses at any stage of gestation are similar, averaging about 14 mrad per mCi of TAC-WBC administered to the mother. The dosimetry of TAC-WBC is favorable enough to permit its use in children, adults and during pregnancy.
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Abstract
Initial clinical trials using strontium-89 (Sr-89) chloride for the treatment of painful skeletal metastases have observed minimal or no hematological depression secondary to the radiostrontium. A patient with marked bone marrow depression temporally related to the administration of the Sr-89 is reported, and the need for close hematological monitoring is emphasized. Bone marrow tumor replacement may predispose patients to marrow depression from radiostrontium, and such patients should be treated with caution.
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Pediatric radiation dose from [111In]leukocytes. J Nucl Med 1986; 27:1220-1. [PMID: 3088225] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
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A new osmium-191/iridium-191m radionuclide generator system using activated carbon. J Nucl Med 1986; 27:380-7. [PMID: 3712057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
A new osmium-191/iridium-191m (191Os/191mIr) radionuclide generator system has been developed based on the absorption of K2OsCl6 (Os-IV) on 140-230 mesh heat-treated activated carbon. The generator is eluted with pH 2 saline solution containing 0.25 g/l Kl to give 191mIr in good yield. The generator eluent is neutralized to physiologic pH and isotonicity with Tris buffer immediately prior to i.v. injection. No scavenger column is required. As an example, elution of the prototype generator with a 2-ml bolus results in elution of 191mIr in approximately 18% yield with an 191Os breakthrough of only 2 X 10(-4)%/bolus. The prototype generator has consistent performance over a 2-wk period with no change in 191mIr yield or 191Os breakthrough. Loading of up to 1.5 Ci of 191Os results in no observed radiolysis. Continuous elution of this system is also possible with a mean 191mIr yield of 3.7%/ml and a mean 191Os breakthrough of 2 X 10(-5)%/ml at a flow rate of 12 ml/min. This new system represents a readily available source of 191mIr for radioangiography. Adsorbed radiation dose calculations indicate a total-body dose of only 3.9 mrad for a 100 mCi injected bolus.
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Contribution of contaminant indium-114m/indium-114 to indium-111 oxine blood dosimetry. J Nucl Med 1985; 26:1091-3. [PMID: 3928839] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Indium-114m and 114In appear as contaminants in commercial preparations of [111In]oxine at a level of about 0.05% at time of calibration (TOC). The contribution of these contaminants to the radiation absorbed dose from [111In]oxine leukocyte, platelet, and erythrocyte imaging procedures has been evaluated. When the absorbed dose from these contaminants is expressed as a percent of the 111In dose to the same organ from a given procedure, the contaminants contribute an additional 0.16 to 12% of the 111In dose, and in one case, that of the spleen from [111In]oxine labeled erythrocytes, they contribute an additional 33%. Commercial samples of aqueous-based [111In]oxine contain levels of 114mIn/114In sufficient to result in a mild to moderate increase in the absorbed radiation dose to the patient. Strict quality control procedures must be maintained by suppliers to prevent higher contamination levels. It is advisable to avoid using 111In products of this nature later than about 3 days after the time of calibration.
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40
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Radiation dosimetry and chemical toxicity considerations for 99Tc. HEALTH PHYSICS 1984; 46:418-422. [PMID: 6319333] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
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41
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Cell labeling: radiation dose and effects. J Nucl Med 1983; 24:637-40. [PMID: 6864318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
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42
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Abstract
Two methods for calculating the radiation dose from remaining body activity have been suggested. One requires correction of the cumulated activities so that they reflect the activity uniformly distributed in the total body. The other method requires correction of the S values so that a value of S for the target organ from the remainder of the body is obtained. These two methods give the same answer. We have examined these methods and the number of steps required to calculate the radiation dose in each case. Our results show that the method of correcting the cumulated activities is preferred, especially if the number of source and target organs is large and a computer equipped with the necessary software is not available.
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Abstract
Histologic studies of liver tissue from 27 patients given up to 395 mCi (cumulative) of intravenous colloidal 198Au showed no definite radiation injury and no correlation between hepatic abnormalities and dose. Demonstration of aggregates of colloidal gold in the Kupffer cells was inconsistent, suggesting slow removal or dispersion. Although the liver ordinarily receives the highest radiation dose, the critical organ is the marrow. Results support the recent introduction of 198Au to supplement teletherapy for certain neoplasms diffusely infiltrating the liver. Apparently the beta distribution minimizes endothelial injury in large vessels, which has been shown to be the cause of radiation hepatitis.
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Abstract
The radiation dose to the lungs from 133Xe in lung air is directly proportional to the time integral of 133Xe concentration; i.e., the cumulated concentration in the lungs. Using kinetic models developed to fit clinical observations, we have studied the effect of retention on cumulated concentration in lung air. The models studied were (1) equal exponential washin and washout rate constants, (2) unequal exponential washin and washout rate constants, and (3) single-compartment washin and two-compartment washout. Our results show that the radiation dose varies greatly with the model chosen. A simplified method for calculating the average dose to the lungs from activity in lung air is presented. Although we have applied this method only to studies where xenon is rebreathed at constant volume and then washed out, the technique can be adapted to other protocols.
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45
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Radiation dose to the liver from 201Ti. J Nucl Med 1975; 16:1089-90. [PMID: 1185273] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
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46
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Whole-body retention of 67Ga-citrate. J Nucl Med 1973; 14:840-2. [PMID: 4743042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
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47
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Calculating the radiation dosage to an organ. J Nucl Med 1973; 14:53-5. [PMID: 4682153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
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48
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Industrial casework. THE TRANSACTIONS OF THE SOCIETY OF OCCUPATIONAL MEDICINE 1967; 17:109-13. [PMID: 6047559 DOI: 10.1093/occmed/17.3.109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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49
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Measuring plutonium in wounds: advantages of using the americium gamma ray. HEALTH PHYSICS 1967; 13:811-813. [PMID: 6026829] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
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