301
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Accardo A, Tesauro D, Roscigno P, Gianolio E, Paduano L, D'Errico G, Pedone C, Morelli G. Physicochemical properties of mixed micellar aggregates containing CCK peptides and Gd complexes designed as tumor specific contrast agents in MRI. J Am Chem Soc 2004; 126:3097-107. [PMID: 15012139 DOI: 10.1021/ja039195b] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
New amphiphilic molecules containing a bioactive peptide or a claw moiety have been prepared in order to obtain mixed micelles as target-specific contrast agents in magnetic resonance imaging. The first molecule, C(18)H(37)CONH(AdOO)(2)-G-CCK8 (C18CCK8), contains a C18 hydrophobic moiety bound to the C-terminal cholecystokinin octapeptide amide (CCK 26-33 or CCK8). The second amphiphilic compound, C(18)H(37)CONHLys(DTPAGlu)CONH(2) (C18DTPAGlu) or its gadolinium complex, (C18DTPAGlu(Gd)), contains the same C18 hydrophobic moiety bound, through a lysine residue, to the DTPAGlu chelating agent. The mixed aggregates as well as the pure C18DTPAGlu aggregate, in the presence and absence of Gd, have been fully characterized by surface tension measurements, FT-PGSE-NMR, fluorescence quenching, and small-angle neutron scattering measurements. The structural characterization of the mixed aggregates C18DTPAGlu(Gd)-C18CCK8 indicates a spherical arrangement of the micelles with an external shell of approximately 21 A and an inner core of approximately 20 A. Both the DTPAGlu(Gd) complexes and the CCK8 peptides point toward the external surface. The measured values for relaxivity in saline medium at 20 MHz proton Larmor frequency and 25 degrees C are 18.7 mM(-)(1) s(-)(1). These values show a large enhancement in comparison with the isolated DTPAGlu(Gd) complex.
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Affiliation(s)
- Antonella Accardo
- Interuniversitario per la Ricerca sui Peptidi Bioattivi (CIRPeB) & Department of Biological Chemistry, University of Naples Federico II Via Mezzocannone, 6 Naples, I-80134, Italy
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302
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Zhang H, Dai M, Qi C, Li B, Guo X. Synthesis, biodistribution and quantitative structure-activity relationship studies of new 99mTc labeled pseudo-peptide complexes. Appl Radiat Isot 2004; 60:643-51. [PMID: 15082041 DOI: 10.1016/j.apradiso.2003.08.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2002] [Accepted: 02/28/2003] [Indexed: 11/25/2022]
Abstract
Twelve new peptide or pseudo-peptide chelators have been synthesized in the course of our continuing investigation of 99mTc-labelled peptides for application for renal imaging agents. All compounds were characterized on the basis of, IR, 1HNMR, 13CNMR spectroscopy, as well as MS and elemental analysis. All peptides yield stable 99mTc complexes using Sn(II) reactive coupling and exhibit renal uptake. Linear regression analysis between Logarithm of renal uptake value (RU) and the parameters obtained by the ZINDO/1 method was performed. Some equations were obtained which showed that molecular polar and charge have some relationship with their renal uptake.
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Affiliation(s)
- Huabei Zhang
- Department of Chemistry, Beijing Normal University, Beijing 100875, China
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303
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Bolzati C, Refosco F, Cagnolini A, Tisato F, Boschi A, Duatti A, Uccelli L, Dolmella A, Marotta E, Tubaro M. Synthesis, Solution-State and Solid-State Structural Characterization of Monocationic Nitrido Heterocomplexes [M(N)(DTC)(PNP)]+ (M =99Tc, Re; DTC = Dithiocarbamate; PNP = Heterodiphosphane). Eur J Inorg Chem 2004. [DOI: 10.1002/ejic.200300666] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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304
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Varvarigou A, Bouziotis P, Zikos C, Scopinaro F, De Vincentis G. Gastrin-Releasing Peptide (GRP) Analogues for Cancer Imaging. Cancer Biother Radiopharm 2004; 19:219-29. [PMID: 15186603 DOI: 10.1089/108497804323072002] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Small neuropeptides, labeled with gamma- and/or beta-emitting radionuclides, are currently being investigated for their ability to bind to cell-surface receptors, overexpressed in a wide variety of malignant tissues being, thus, potentially useful for radionuclide detection and/or therapy for tumors. Particular attention has been focused on the amphibian peptide, bombesin (BN), and the molecularly related gastrin-releasing peptide (GRP). These peptides act as neurotransmitters and endocrine cancer cell-growth factors on normal tissues as well as on neoplastic cells of various origin. In recent investigations, modification of the native peptide structure has been attempted in order to obtain derivatives, which might easily be labeled with radionuclides. Thus, iodinated (I-125) BN derivatives, as well as Indium (In-111) labeled BN analogs are currently being investigated, presenting satisfactory tumor localization. Also, some new BN analogs containing a 6-carbon linker have been prepared and labeled with Rhenium-188, resulting in positive in vitro binding to prostate cancer cells. More recent studies refer to the Technetium-99m labeling of BN, performed either directly, after attaching proper technetium-chelating groups onto the BN sequence, or indirectly, by coupling BN to a preformed 99mTc-tagging ligand. Both types of conjugates were found to have a high in vitro affinity for cells with BN receptors, also presenting satisfactory in vivo uptake in experimental tumor models. Pilot clinical studies of a new BN-derived, 99mTc-labeled pentadecapeptide indicated significant uptake by breast cancer and invaded lymph nodes, as well as by prostate cancer, small-cell lung carcinoma, gastro-entero-pancreatic tumors, and others, Further studies of this new GRP derivative, as well as of other new BN-like peptides, are intensively performed internationally today.
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Affiliation(s)
- Alexandra Varvarigou
- Radiodiagnostics Institute, National Center for Scientific Research Demokritos, Athens, Greece.
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305
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Banerjee SR, Babich JW, Zubieta J. Bifunctional chelates with aliphatic amine donors for labeling of biomolecules with the {Tc(CO) 3 } + and {Re(CO) 3 } + cores: the crystal and molecular structure of [Re(CO) 3 {(H 2 NCH 2 CH 2 ) 2 N(CH 2 ) 4 CO 2 Me}]Br. INORG CHEM COMMUN 2004. [DOI: 10.1016/j.inoche.2004.01.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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306
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Complexes of the fac-{Re(CO)3}+ core with tridentate ligands derived from arylpiperazines. Inorganica Chim Acta 2004. [DOI: 10.1016/j.ica.2003.11.027] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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307
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Tubaro M, Marotta E, Tisato F, Bolzati C, Porchia M, Refosco F, Tomasin P, Cavazza-Ceccato M, Traldi P. Electrospray mass spectrometry of a series of mixed nitrido 99gTc- heterocomplexes conjugated with bioactive molecules. EUROPEAN JOURNAL OF MASS SPECTROMETRY (CHICHESTER, ENGLAND) 2004; 10:605-611. [PMID: 15531793 DOI: 10.1255/ejms.677] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Electrospray ionization mass spectrometry (ESI-MS) was successfully employed for the identification of six nitrido technetium mixed ligand complexes with a general formula of [99gTc(N)(O,S-BID)(PNP)], where PNP represents a heterodiphosphine and O,S-BID represents a simple dianionic bidentate ligand (compounds 1-3) or a more sophisticated N-substituted O,S-cysteine framework conjugated with a bio- active molecule (BAM) (compounds 4-6). In spite of similar coordination spheres exhibited by all the complexes investigated, simple co-ordination compounds 1-3 displayed collisionally-induced fragmentation processes (MSn) different from those observed in biomolecule-containing compounds 4-6. In the latter, more decomposition channels were observed. This behavior is likely to be associated with some additional intramolecular contacts of the biomolecule (or part of the biomolecule) with pendant group(s) incorporated in the PNP-co-ligand. This view is further supported by the observations arising from both in vitro binding affinity experiments and nuclear magnetic resonance investigations. The presence of cationized forms for all compounds 1-6 and the practical lack of the [2M + Na]+ species for biomolecule-containing compounds 4-6 provided further evidence of a subtly different structural conformation.
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Affiliation(s)
- Michela Tubaro
- CNR, Istituto di Scienze e Tecnologie Molecolari, Corso Stati Uniti 4, I-35127 Padova, Italy
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308
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Mundwiler S, Kündig M, Ortner K, Alberto R. A new [2 + 1] mixed ligand concept based on [99(m)Tc(OH2)3(CO)3]+: a basic study. Dalton Trans 2004:1320-8. [PMID: 15252624 DOI: 10.1039/b400220b] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Mixed ligand fac-tricarbonyl complexes of the general formula [M(L1)(L2)(CO)3](M = Re, 99(m)Tc, L1= imidazole, benzyl isocyanide, L2 = 1H-imidazole-4-carboxylic acid, pyridine-2,4-dicarboxylic acid, pyridine-2,5-dicarboxylic acid) have been prepared starting from the precursors [M(OH2)3(CO)3]+. The complexes can be obtained in good yield and purity in a two-step procedure by first attaching the bidentate ligand followed by addition of the monodentate. 99mTc compounds can also be prepared at the tracer level in one-pot procedures with L1 and L2 being concomitantly present. This [2 + 1] approach allows the labeling of bioactive molecules containing a monodentate or a bidentate donor site. Examples given in here are N-(tert-butoxycarbonyl)glycyl-N-(3-(imidazol-1-yl)propyl)phenylalaninamide, 5-((3-(imidazol-1-yl)propyl)aminomethyl)-2'-deoxyuridine and 4-(5-isonitrilpentyl)-1-(2-methoxyphenyl)-piperazine as L1 and N-((6-carboxypyridine-3-yl)methyl)glycylphenylalanine as L2. The corresponding second ligand can be used to influence the physico-chemical properties of the conjugate. The crystal structures of [99Tc(OH2)(imc)(CO)3], [Re(OH2)(2,4-dipic)(CO)3], [Re(bic)(2,4-dipic)(CO)3] and [Re(im)(2,5-dipic)(CO)3] are reported.
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Affiliation(s)
- Stefan Mundwiler
- Institute of Inorganic Chemistry, University of Zürich, 8057 Zürich, Switzerland
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309
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Fernandes C, Patrício L, Moreira R, Cantinho G, Pena H, Campello PC, Santos I. Novel 3+1 mixed-ligand Technetium-99m complexes carrying dipeptides as monodentate ligands. Nucl Med Biol 2004; 31:139-46. [PMID: 14741579 DOI: 10.1016/s0969-8051(03)00129-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Novel mixed ligand oxotechnetium complexes of the type [99mTcO(SSS)(SR)], in which the SR monodentate ligand is derived from dipeptides gly-gly, phe-gly and ala-gly, have been synthesized. These complexes, which have a molecular weight above 300, a lipophilic moiety, [TcO(SSS)]+, and an ionizable group separated from the lipophilic moiety by a spacer, have been obtained in 70-95% radiochemical yield. These compounds were prepared using 99mTc-tartrate as the precursor and Sn2+ as the reducing agent. The identity of the [99mTcO(SSS)(SR)] complexes has been established by HPLC comparison with the analogous oxorhenium complexes. The nature of the monodentate co-ligand strongly affects the stability of the 99mTc-complexes and their biodistribution. Complex 3b is the most stable in vitro presenting the highest blood clearance, a high liver uptake and a selective hepatobiliary excretion (54.5% ID at 15 min post-injection, and 69.3% ID at 60 min post injection). The results obtained show that 3b have reasonable stability and in vivo properties that may be useful for peptide labeling.
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Affiliation(s)
- Célia Fernandes
- Departamento de Química, ITN, Estrada Nacional 10, 2686-953 Sacavém, Codex, Portugal.
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310
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Alberto R, Cowley AR, Dilworth JR, Donnelly PS, Pratt J. Diazenide and hydrazide(2−) derivatives of the [Re(CO)3]+core. Dalton Trans 2004:2610-1. [PMID: 15514740 DOI: 10.1039/b407708c] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Reaction of [ReBr3(CO)3]2- with aryldiazonium salts gives the Re(iii) diazenide complexes [ReBr2(NNC6H4R-4)(CO)2]-. The attachment of a PhNHCS tethering group to pyridyl hydrazine generates a HYNIC related proligand which gives a stable chelated pyridyliumthiocarbazide(2-) derivative of the [Re(I)(CO)3]+ core.
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Affiliation(s)
- Roger Alberto
- Institute of Inorganic Chemistry, University of Zürich, Winterhurerstrasse 190, Switzerland
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311
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Okarvi SM. Peptide-based radiopharmaceuticals: Future tools for diagnostic imaging of cancers and other diseases. Med Res Rev 2004; 24:357-97. [PMID: 14994368 DOI: 10.1002/med.20002] [Citation(s) in RCA: 165] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Small synthetic receptor-binding peptides are the agents of choice for diagnostic imaging and radiotherapy of cancers due to their favorable pharmacokinetics. Molecular modification techniques permit the synthesis of a variety of bioactive peptides with chelating groups, without compromising biological properties. Various techniques have been developed that allow efficient and site-specific labeling of peptides with clinically useful radionuclides such as (99m)Tc, (123)I, (111)In, and (18)F. Among them, (99m)Tc is the radionuclide of choice because of its excellent chemical and imaging characteristics. Recently, many (99m)Tc-labeled peptides have proven to be useful imaging agents. Beside (99m)Tc-labeled peptides, several peptides radiolabeled with (111)In and (123)I have been prepared and characterized. In addition, (18)F-labeled peptides hold clinical potential due to their ability to quantitatively detect and characterize a variety of human diseases using positron-emission tomography. The availability of this wide range of peptides labeled with different radionuclides offers multiple diagnostic and therapeutic applications. Various receptors are over-expressed in particular tumor types and peptides binding to these receptors can be used to visualize tumor lesions scintigraphically. Thus, radiolabeled peptides have potential use as carriers for the delivery of radionuclides to tumors, infarcts, and infected tissues for diagnostic imaging and radiotherapy. Many radiolabeled peptides are currently under investigation to determine their potential as imaging agents. These peptides are designed mainly for thrombus, tumor, and infection/inflammation imaging. This article presents recent developments in small synthetic peptides for imaging of thrombosis, tumors, and infection/inflammation.
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Affiliation(s)
- Subhani M Okarvi
- Cyclotron and Radiopharmaceuticals Department, King Faisal Specialist Hospital and Research Centre, P.O. Box 3354, Riyadh 11211, Kingdom of Saudi Arabia.
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312
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Baril-Robert F, Beauchamp AL. Preparation and electronic properties of rhenium(V) complexes with bis(diphenyl phosphino)ethane. CAN J CHEM 2003. [DOI: 10.1139/v03-143] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Complexes of bis(diphenylphosphino)ethane (dppe) of the types ReOX3(dppe) and ReO(OR)X2(dppe) (with X= Cl or Br, and R = Me, Et, Pr, Ph, cyclohexyl (Cy), or -CH2CH2OH) were prepared to evaluate the influence of ligand changes on the low-energy dd transitions in these Re(V) low-spin d2 systems. Arylimido compounds Re(NR)Cl3(dppe) (with R = Ph and p-ClC6H4) were also obtained. X-ray diffraction studies on ReO(OPr)Cl2(dppe), ReO(OPh)Br2(dppe), and ReO(OCy)Cl2(dppe) confirmed the presence of the trans O=Re-OR unit and showed that the structural characteristics of the Re-O-R segment are not affected by the presence of a bulky cyclohexyl substituent or an aromatic phenyl group. The structure of the arylimido complex Re(p-ClC6H4N)Cl3(dppe) was also determined. The electronic absorption spectra of the ReOX3(dppe) compounds include two low-energy components at ~11 500 and ~16 000 cm1, assigned to the two spin-allowed dd transitions expected for these low-symmetry systems. Substitution of the oxo ligand by an arylimido group has little effect on the lower-energy component, but moves the two components closer together. Replacing the halogen trans to the Re=O bond by an alkoxo group shifts the whole system to higher energies. These variations were found to correlate well with the energies of the frontier orbitals determined from DFT calculations. While attempting to prepare ReOCl3(dppe) from ReOCl3(PPh3)2, the Re(III) compound fac-ReCl3(PPh3){Ph2PC2H4PPh2(O)} was obtained, in which one end of dppe had become a phosphine oxide. Upon standing in DMSO, this compound gave the octahedral compound ReCl4{Ph2PC2H4PPh2(O)}, in which the formation of a chelate ring involving a phosphine and a phosphine oxide was ascertained by X-ray diffraction.Key words: rhenium, crystal structure, DFT calculations, dd electron transitions.
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313
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Abstract
The phrase "molecular imaging" is unquestionably current and is receiving ever increasing use. For example, two organizations, the Institute for Molecular Imaging and the Academy of Molecular Imaging have recently been established with molecular imaging as their focus, with journal entitled "Molecular Imaging" and "Molecular Imaging and Biology," respectively. Furthermore, the two leading journals in the field of nuclear medicine have recently added this phrase to their covers-becoming the "European Journal of Nuclear Medicine and Molecular Imaging" and "The Journal of Nuclear Medicine-advancing molecular imaging." The National Institute of Biomedical Imaging and Bioengineering is the newest institute of the NIH. With this degree of attention, it may be surprising that there is as yet no universally accepted definition of molecular imaging. Numerous diverse definitions, some quite complex, have been proposed. With some exceptions, they all refer to imaging in the living animal of function at the cellular or molecular level. Thus molecular imaging may be defined as the observation of biological function at the molecular level in health and disease through some process involving non-invasive imaging of the living mammals.
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Affiliation(s)
- D J Hnatowich
- Division of Nuclear Medicine, Department of Radiology, University of Massachusetts Medical School, Worcester, Massachusetts, USA.
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314
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Wild D, Schmitt JS, Ginj M, Mäcke HR, Bernard BF, Krenning E, De Jong M, Wenger S, Reubi JC. DOTA-NOC, a high-affinity ligand of somatostatin receptor subtypes 2, 3 and 5 for labelling with various radiometals. Eur J Nucl Med Mol Imaging 2003; 30:1338-47. [PMID: 12937948 DOI: 10.1007/s00259-003-1255-5] [Citation(s) in RCA: 217] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2003] [Accepted: 05/24/2003] [Indexed: 10/26/2022]
Abstract
Earlier studies have shown that modification of the octapeptide octreotide in positions 3 and 8 may result in compounds with increased somatostatin receptor affinity that, if radiolabelled, display improved uptake in somatostatin receptor-positive tumours. The aim of a recent research study in our laboratory was to employ the parallel peptide synthesis approach by further exchanging the amino acid in position 3 of octreotide and coupling the macrocyclic chelator DOTA(1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) to these peptides for labelling with radiometals like gallium-67 or -68, indium-111, yttrium-90 and lutetium-177. The purpose was to find radiopeptides with an improved somatostatin receptor binding profile in order to extend the spectrum of targeted tumours. A first peptide, [111In,90Y-DOTA]-1-Nal3-octreotide (111In,90Y-DOTA-NOC), was isolated which showed an improved profile. InIII-DOTA-NOC exhibited the following IC50 values (nM) when studied in competition with [125I][Leu8, d-Trp22, Tyr25]somatostatin-28 (values for YIII-DOTA-NOC are shown in parentheses): sstr2, 2.9 +/- 0.1 (3.3 +/- 0.2); sstr3, 8 +/- 2 (26 +/- 1.9); sstr5, 11.2 +/- 3.5 (10.4 +/- 1.6). Affinity towards sstr1 and 4 was very low or absent. InIII-DOTA-NOC is superior to all somatostatin-based radiopeptides having this particular type of binding profile, including DOTA-lanreotide, and has three to four times higher binding affinity to sstr2 than InIII,YIII-DOTA-Tyr3-octreotide (InIII,YIII-DOTA-TOC). In addition, [111In]DOTA-NOC showed a specific and high rate of internalization into AR4-2J rat pancreatic tumour cells which, after 4 h, was about two times higher than that of [111In]DOTA-TOC and three times higher than that of [111In]DOTA-octreotide ([111In]DOTA-OC). The internalized radiopeptides were externalized intact upon 2 h of internalization followed by an acid wash. After 2-3 h of externalization a plateau is reached, indicating a steady-state situation explained by reactivation of the receptors followed by re-endocytosis. Biodistribution studies in CA 20948 tumour-bearing rats showed rapid clearance from all sstr-negative tissues except the kidneys. At 4 h the uptake of [111In]DOTA-NOC in the tumour and sstr-positive tissues, such as adrenals, stomach and pancreas, was three to four times higher than that of [111In]DOTA-TOC. Differential blocking studies indicate that this is at least partially due to the uptake mediated by sstr3 and sstr5. These very promising preclinical data justify the use of this new radiopeptide for imaging and potentially internal radiotherapy studies in patients.
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Affiliation(s)
- Damian Wild
- Division of Radiological Chemistry, Institute of Nuclear Medicine, Department of Radiology, University Hospital Basel, Basel, Switzerland
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315
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Papachristou M, Pirmettis I, Siatra-Papastaikoudi T, Pelecanou M, Tsoukalas C, Raptopoulou C, Terzis A, Chiotellis E, Papadopoulos M. Synthesis and Characterization of Oxorhenium and Oxotechnetium Complexes with a Novel Tetradentate N3O Bifunctional Agent. Eur J Inorg Chem 2003. [DOI: 10.1002/ejic.200300298] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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316
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Arterburn JB, Bryant BK, Chen D. Synthesis of (pyridin-2-yl)hydrazine conjugates as bifunctional chelates using the Suzuki-Miyaura reaction. Chem Commun (Camb) 2003:1890-1. [PMID: 12932018 DOI: 10.1039/b304153k] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Palladium catalyzed C-C couplings were used to connect (pyridin-2-yl)hydrazine to organic substrates, including a phenylalanine derivative, providing a new method for introducing this important ligand.
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Affiliation(s)
- Jeffrey B Arterburn
- Department of Chemistry & Biochemistry MSC 3C, New Mexico State University, Box 30001, Las Cruces, New Mexico 88003, USA.
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317
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Machura B, Dziȩgielewski J, Kusz J. The synthesis, spectroscopic investigation, crystal and molecular structure of the [ReBrCl2(SbPh3)3] complex. INORG CHEM COMMUN 2003. [DOI: 10.1016/s1387-7003(03)00120-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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318
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Oxorhenium(V) complexes with bis-phosphinite chelating coligands. The crystal structure of [ReOCl2(OMe)L1], [ReOCl3L2], [ReOCl2(OEt)L2] and [ReOCl2{Ph2PO(CH2)2O}{PPh2(OEt)}] [L1=Cy2PO(CH2)2OPCy2, L2=Ph2PO(CH2)2OPPh2]. Polyhedron 2003. [DOI: 10.1016/s0277-5387(03)00334-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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319
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Abstract
In biological systems metal ions promote responses that range from deficiency to toxicity. Some, such as iron and zinc, have a known optimal intake range for normal, healthy individuals. Metal ions contained within well-designed molecules already constitute a great boon for the medicinal pharmacopoeia. However, whether essential or not, the threshold for toxicity can be very low. One of the challenges of designing metal-based drugs is to balance the potential toxicity of an active formulation with the substantial positive impact of these increasingly common therapeutic and diagnostic aids.
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Affiliation(s)
- Katherine H Thompson
- Medicinal Inorganic Chemistry Group, Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, BC V6T 1Z1, Canada
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320
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Kothari KK, Raghuraman K, Pillarsetty NK, Hoffman TJ, Owen NK, Katti KV, Volkert WA. Syntheses, in vitro and in vivo characterization of a 99mTc-(I)-tricarbonyl-benzylamino-dihydroxymethyl phosphine (NP(2)) chelate. Appl Radiat Isot 2003; 58:543-9. [PMID: 12735970 DOI: 10.1016/s0969-8043(03)00030-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Studies were performed to study the complexation chemistry of 99mTc(CO)(+)(3) with a new tridentate amino-dihydroxymethyl phosphine (NP(2)) ligand with the 99mTc(CO)(3)(OH(2))(+)(3) synthon at tracer levels. A single, well-defined 99mTc(CO)(3)NP(2) complex is formed at pH 7.5 within 10 min at 60 degrees C that exhibits high in vitro and in vivo stability.
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Affiliation(s)
- K K Kothari
- Radiopharmaceuticals Chemistry Section, Radiopharmaceuticals Division, Bhabha Atomic Center, Mumbai 400085, India.
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321
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Papagiannopoulou D, Pirmettis I, Pelecanou M, Tsoukalas C, Raptopoulou C, Terzis A, Chiotellis E, Papadopoulos M. Synthesis and structural characterization of a novel Re[P][NN][S][SO] mixed ligand rhenium(III) complex. Inorganica Chim Acta 2003. [DOI: 10.1016/s0020-1693(02)01377-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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322
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Signore A, Annovazzi A, Corsetti F, Capriotti G, Chianelli M, De Winter F, Scopinaro F. Biological imaging for the diagnosis of inflammatory conditions. BioDrugs 2003; 16:241-59. [PMID: 12196038 DOI: 10.2165/00063030-200216040-00002] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Radiopharmaceuticals used for in vivo imaging of inflammatory conditions can be conveniently classified into six categories according to the different phases in which the inflammatory process develops. The trigger of an inflammatory process is a pathogenic insult (phase I) that causes activation of endothelial cells (phase II); there is then an increase of vascular permeability followed by tissue oedema (phase III). Phase IV is characterised by infiltration of polymorphonuclear cells, and a self-limiting regulatory process called apoptosis is observed (phase V). If the inflammatory process persists, late chronic inflammation takes place (phase VI). In some pathological conditions, such as organ-specific autoimmune diseases, chronic inflammation is present early in the disease. The aim of nuclear medicine in the field of inflammation/infection is to develop noninvasive tools for the in vivo detection of specific cells and tissues. This would allow early diagnosis of initial pathophysiological changes that are undetectable by clinical examination or by other diagnostic tools, and could also be used to evaluate the state of activity of the disease during therapy. These potential applications are of great interest in clinical practice. In this review, we describe the various approaches that have been developed in the last 25 years of experience. Recent advances in the diagnosis of inflammatory processes have led to the development of specific radiopharmaceuticals that are intended to allow specific stage-related diagnosis.
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Affiliation(s)
- Alberto Signore
- Department of Clinical Sciences, Nuclear Medicine, 2nd Faculty of Medicine, University of Rome, La Sapienza, Rome, Italy.
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323
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A peptide approach to covalently linked [Ru(bipy)3]2+–ferrocene and [Ru(bipy)3]2+–tyrosine conjugates. Inorganica Chim Acta 2003. [DOI: 10.1016/s0020-1693(02)01339-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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324
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Su ZF, He J, Rusckowski M, Hnatowich DJ. In vitro cell studies of technetium-99m labeled RGD-HYNIC peptide, a comparison of tricine and EDDA as co-ligands. Nucl Med Biol 2003; 30:141-9. [PMID: 12623113 DOI: 10.1016/s0969-8051(02)00390-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
UNLABELLED The level of alpha(V)beta(3) integrins on endothelial cells is elevated in angiogenesis. The high binding specificity to alpha(V)beta(3) integrins of peptides containing Arg-Gly-Asp (RGD) residues suggests that the radiolabeled RGD peptides may be useful as tumor specific imaging agents. In this research, cyclised peptides containing Arg-Gly-Asp (RGD) and Arg-Gly-Glu (RGE, as control) residues were conjugated with HYNIC and labeled with (99m)Tc. OBJECTIVE The goal was to evaluate the influence of co-ligand, either tricine or ethylenediamine-N,N'-diacetic acid (EDDA) on protein and integrin binding and on cellular uptake in culture. METHODS The n-octanol/water partition coefficient, binding to bovine serum albumin (BSA) and human umbilical vein endothelial (HUVE) cells, and cell lysate distributions of the radiolabeled peptides were evaluated. RESULTS The co-ligands had a significant effect on the labeling efficiency of the HYNIC conjugates and on certain properties of the (99m)Tc complexes. The labeling efficiency with tricine was 10 fold higher and BSA binding was over 8 fold greater compared to EDDA. Both RGD labels showed higher (6 to 28 fold) binding to HUVE cells than that of the RGE labels, indicating binding specificity. After cell-lysis, only a small percentage of the total RGD label that accumulated in the cells was found bound to cellular proteins (9% of RGD/tricine and 5% of RGD/EDDA), implying that over 90% of the radiolabeled peptides were internalized for both radiolabeled RGDs. The number of the RGD molecules bound to proteins was estimated to be approximately three per cell, suggesting that only a small number of alpha(V)beta(3) integrin proteins are expressed on the cells. CONCLUSIONS Apart from the differences in radiolabeling, the only important effect of substituting EDDA for tricine as co-ligand on the HYNIC-peptides was the lower degree of serum protein binding. In spite of the lower serum protein binding potential, in vivo tumor accumulation of the RGD/EDDA may not be improved compared to RGD/tricine since quantitation of the cell binding results suggests that the number of alpha(V)beta(3) integrin proteins per cell might be limited.
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Affiliation(s)
- Zi-Fen Su
- Division of Nuclear Medicine, Department of Radiology, University of Massachusetts Medical School, Worcester, MA 01655, USA
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Tsoukalas C, Pirmettis I, Patsis G, Pelecanou M, Bodo K, Raptopoulou CP, Terzis A, Papadopoulos M, Chiotellis E. Novel oxorhenium and oxotechnetium MO(NS)(S)2 complexes in the development of 5-HT1A receptor imaging agents. J Inorg Biochem 2003; 93:213-20. [PMID: 12576284 DOI: 10.1016/s0162-0134(02)00574-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The [NS][S](2) mixed-ligand system was applied to synthesize oxorhenium and oxotechnetium complexes of the general formula MO(o-CH(3)OC(6)H(4)N(CH(2)CH(2))(2)NCH(2)CH(2)S)(p-CH(3)C(6)H(4)S)(2) (M=Re in 1, M=(99)Tc in 2, and M=(99m)Tc in 3). The bidentate [NS] ligand includes the 1-(2-methoxyphenyl)piperazine moiety which is a fragment of the true 5-HT(1A) antagonist WAY 100635. The oxorhenium complex 1 was prepared by a ligand exchange reaction using ReOCl(3)(PPh(3))(2) as precursor while [Bu(4)N][(99)TcOCl(4)] and (99)Tc-gluconate were used as precursors in the synthesis of the oxotechnetium-99 complex 2. Both complexes were characterized by elemental analysis and spectroscopic methods. Crystallographic analysis of 1 showed that the rhenium coordination geometry is trigonal bipyramidal. The basal plane of the trigonal bipyramid is defined by the oxo group and two sulphur atoms, one belonging to the [NS] ligand and the other to an aromatic thiol, while the apical positions are occupied by the nitrogen of the [NS] ligand and the sulphur of the second aromatic thiol. The oxotechnetium-99 complex 2 has almost identical unit cell parameters to those of the oxorhenium complex 1 indicating, in combination with the other analytical data, that the complexes are isostructural. The binding affinity of the oxorhenium complex 1 for the 5-HT(1A) receptor subtype was determined in rat brain hippocampal preparations (IC(50)=106 nM). The oxotechnetium-99m complex 3 was prepared by a ligand exchange reaction using (99m)Tc-glucoheptonate as the precursor. Its structure was established by comparative HPLC studies using the oxotechnetium-99 complex 2 as a reference. Complex 3 was administered by intravenous injection in rats. At 2 min post injection, 0.153% of the injected dose per gram of tissue was measured in rat brain.
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Affiliation(s)
- Charalambos Tsoukalas
- Institute of Radioisotopes-Radiodiagnostic Products, National Centre for Scientific Research 'Demokritos', 15310 Ag. Paraskevi, Athens, Greece
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326
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Patsis G, Pirmettis I, Tsoukalas C, Pelecanou M, Raptopoulou CP, Terzis A, Papadopoulos M, Chiotellis E. Synthesis and characterization of binuclear μ-oxorhenium mixed ligand complexes containing tridentate (SNSEt) and monodentate (SR) ligands. Inorganica Chim Acta 2003. [DOI: 10.1016/s0020-1693(02)01160-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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327
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Frydman L, Scherf T, Lupulescu A. The acquisition of multidimensional NMR spectra within a single scan. Proc Natl Acad Sci U S A 2002; 99:15858-62. [PMID: 12461169 PMCID: PMC138528 DOI: 10.1073/pnas.252644399] [Citation(s) in RCA: 441] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A scheme enabling the complete sampling of multidimensional NMR domains within a single continuous acquisition is introduced and exemplified. Provided that an analyte's signal is sufficiently strong, the acquisition time of multidimensional NMR experiments can thus be shortened by orders of magnitude. This could enable the characterization of transient events such as proteins folding, 2D NMR experiments on samples being chromatographed, bring the duration of higher dimensional experiments (e.g., 4D NMR) into the lifetime of most proteins under physiological conditions, and facilitate the incorporation of spectroscopic 2D sequences into in vivo imaging investigations. The protocol is compatible with existing multidimensional pulse sequences and can be implemented by using conventional hardware; its performance is exemplified here with a variety of homonuclear 2D NMR acquisitions.
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Affiliation(s)
- Lucio Frydman
- Departments of Chemical Physics and Chemical Services, Weizmann Institute of Science, 76100 Rehovot, Israel Middle East.
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328
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Banerjee SR, Levadala MK, Lazarova N, Wei L, Valliant JF, Stephenson KA, Babich JW, Maresca KP, Zubieta J. Bifunctional single amino acid chelates for labeling of biomolecules with the [Tc(CO)(3)](+) and [Re(CO)(3)](+) cores. Crystal and molecular structures of [ReBr(CO)(3)(H(2)NCH(2)C(5)H(4)N)], [Re(CO)(3)[(C(5)H(4)NCH(2))(2)NH]]Br, [Re(CO)(3)[(C(5)H(4)NCH(2))(2)NCH(2)CO(2)H]]Br, [Re(CO)(3)[X(Y)NCH(2)CO(2)CH(2)CH(3)]]Br (X = Y = 2-pyridylmethyl; X = 2-pyridylmethyl, Y = 2-(1-methylimidazolyl)methyl; X = Y = 2-(1-methylimidazolyl)methyl), [ReBr(CO)(3)[(C(5)H(4)NCH(2))NH(CH(2)C(4)H(3)S)]], and [Re(CO)(3)[(C(5)H(4)NCH(2))N(CH(2)C(4)H(3)S)(CH(2)CO(2))]]. Inorg Chem 2002; 41:6417-25. [PMID: 12444786 DOI: 10.1021/ic020476e] [Citation(s) in RCA: 149] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The reactions of a series of potentially tridentate ligands, derived from single amino acids or amino acid analogues, with [NEt(4)](2)[ReBr(3)(CO)(3)] have been investigated. The model compounds [Re(CO)(3)Br[(2-pyridylmethyl)NH(2)]] (1) and [Re(CO)(3)[(2-pyridylmethyl)(2)NH]]Br (2) were also prepared and structurally characterized. With ligands possessing two pyridyl appendages, (2-pyridylmethyl)(2)NX (X = -CH(2)CO(2)H, -CH(2)CO(2)Et, -CH(2)CH(2)CO(2)H, -CH(2)CH(2)CO(2)Et, -CH(2)CH(2)CH(2)CH(2)CH(NHCO(2)(t)Bu)CO(2)H), complexes of the type [Re(CO)(3)(ligand)]Br (3-6) were isolated. All possess the fac-[Re(CO)(3)N(3)] coordination geometry in the cationic molecular unit. Similarly, the ligands with the imidazolyl arms (2-pyridylmethyl)[2-(1-methylimidazolyl)methyl]NCH(2)CO(2)Et and [2-(1-methylimidazolyl)methyl](2)NCH(2)CO(2)Et, complexes 7 and 8 of the same [Re(CO)(3)(ligand)]Br type, were prepared. Replacement of one pyridyl arm with a thiophene group yielded the complex [Re(CO)(3)[(2-pyridylmethyl)N(CH(2)CO(2))(2-thiophenemethyl)]] (9), while additional substitution of X = -H for -CH(2)CO(2)H yielded [Re(CO)(3)Br[(2-pyridylmethyl)NH(2-thiophenemethyl)]] (10). In both 9 and 10, the thiophene is uncoordinated and pendant, and the derivatives display fac-[Re(CO)(3)N(2)O] and fac-[Re(CO)(3)N(2)Br] coordination geometries, respectively. Crystal data: C(9)H(8)BrN(2)O(3)Re (1), triclinic P1, a = 8.156(1) A, b = 12.077(1) A, c = 12.945(2) A, alpha = 92.183(3) degrees, beta = 107.848(3) degrees, gamma = 100.955(7) degrees, V = 1185.1(3) A, Z = 4; C(15)H(13)BrN(3)O(3)Re (2), tetragonal P4(1), a = 8.6095(3) A, c = 22.228(1) A, V = 1646.9(1) A(3), Z = 4; C(17)H(14)BrN(3)O(5)Re.CH(3)OH (3), monoclinic P2(1)/m, a = 7.4425(3) A, b = 9.7596(4) A, c = 14.0646(6) A, beta = 97.753(1) degrees, V = 1012.26(7) A(3), Z = 2; C(19)H(19)BrN(3)O(5)Re (4), tetragonal P42(1)c, a = 16.895(3) A, c = 15.042(3) A, V = 4293.7(13) A(3), Z = 8; C(18)H(20)BrN(4)O(5)Re.CH(3)OH.H(2)O (7), monoclinic P2(1)/c, a = 10.2816(4) A, b = 30.386(1) A, c = 14.5810(6) A, beta = 99.868(1) degrees, V = 4488.03(3) A(3), Z = 8; C(17)H(21)BrN(5)O(5)Re.0.5CH(2)Cl(2).0.5H(2)O (8), triclinic P1, a = 11.5363(6) A, b = 13.1898(6) A, c = 16.4933(8) A, alpha = 89.356(1) degrees, beta = 74.907(1) degrees, gamma = 76.216(1) degrees, V = 2349.8(2) A(3), Z = 4; C(16)H(13)N(2)O(5)ReS (9), monoclinic P2(1)/c, a = 17.2072(7) A, b = 8.5853(4) A, c = 11.5607(5) A, beta = 101.73(1) degrees, V = 1672.2(1) A(3), Z = 4; and C(14)H(12)N(2)O(3)BrReS (10), triclinic P1, a = 7.5585(3) A, b = 9.7713(4) A, c = 11.7103(4) A, alpha = 109.566(1) degrees, beta = 98.298(1) degrees, gamma = 100.925(1) degrees, V = 779.73(5) A(3), Z = 2.
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Gambino D, Kremer E, Baran EJ. Infrared spectra of new Re(III) complexes with thiourea derivatives. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2002; 58:3085-3092. [PMID: 12511092 DOI: 10.1016/s1386-1425(02)00106-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Complexes of the type [Re(III)L6]X3, with L = thiourea, N-methylthiourea, N-ethylthiourea or N,N'-dimethytlthiourea and X = Cl- or PF6-, were prepared as suitable precursors for the synthesis of new rhenium complexes potentially useful in nuclear medicine. The infrared (IR) spectra of these complexes were recorded and analyzed and a general vibrational pattern for Re(III) complexes with thiourea derivatives could be established. Approximate assignments for N-allylthiourea and N-ethylthiourea are also proposed for the first time. The synthesis of the new complex [Re(III)(N-allylthiourea)6](PF6)3 is also reported, and information about its structural characteristics was obtained comparing its IR spectrum with those of the other complexes of the investigated series.
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Affiliation(s)
- Dinorah Gambino
- Cátedra de Química Inorgánica, Facultad de Química, Universidad de la República, 1300-Montevideo, Uruguay
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330
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Jones JR, Lu SY, Shevchenko VP, Nagaev IY, Myasoedov NF, Susan AB, Anderskerskevitz R, Birke FW, Switek KH, Wiegerinck P, Post O, Hofstede L, van den Heuvel M, Pleiss U, Seidel D, Switek KH, Braunger H, Seidel D, Schlecker R, Moenius T, Seiler MP, Nozulak J, Burtscher P, Almi M, Guelfi S, Navacchia ML, Felicini C, Giribone D, Pignatti A, Fontana E, Pignatti A, Fontana E, McGrath JW, Peric Simov B, Preusser W, Quinn JP, Schmidt S, Woschek A, Wuggenig F, Hammerschmidt F, Spies H, Maas J, Krone V, Diehl F, Coy J, Hoheisel J, Doeberitz MVK, Nees M, Klett A. 10th Conference of the Central European Division e.V. of the International Isotope Society. J Labelled Comp Radiopharm 2002. [DOI: 10.1002/jlcr.658] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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331
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Sharma V, Luker GD, Piwnica-Worms D. Molecular imaging of gene expression and protein function in vivo with PET and SPECT. J Magn Reson Imaging 2002; 16:336-51. [PMID: 12353250 DOI: 10.1002/jmri.10182] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Molecular imaging is broadly defined as the characterization and measurement of biological processes in living animals, model systems, and humans at the cellular and molecular level using remote imaging detectors. One underlying premise of molecular imaging is that this emerging field is not defined by the imaging technologies that underpin acquisition of the final image per se, but rather is driven by the underlying biological questions. In practice, the choice of imaging modality and probe is usually reduced to choosing between high spatial resolution and high sensitivity to address a given biological system. Positron emission tomography (PET) and single-photon emission computed tomography (SPECT) inherently use image-enhancing agents (radiopharmaceuticals) that are synthesized at sufficiently high specific activity to enable use of tracer concentrations of the compound (picomolar to nanomolar) for detecting molecular signals while providing the desired levels of image contrast. The tracer technologies strategically provide high sensitivity for imaging small-capacity molecular systems in vivo (receptors, enzymes, transporters) at a cost of lower spatial resolution than other technologies. We review several significant PET and SPECT advances in imaging receptors (somatostatin receptor subtypes, neurotensin receptor subtypes, alpha(v)beta(3) integrin), enzymes (hexokinase, thymidine kinase), transporters (MDR1 P-glycoprotein, sodium-iodide symporter), and permeation peptides (human immunodeficiency virus type 1 (HIV-1) Tat conjugates), as well as innovative reporter gene constructs (herpes simplex virus 1 thymidine kinase, somatostatin receptor subtype 2, cytosine deaminase) for imaging gene promoter activation and repression, signal transduction pathways, and protein-protein interactions in vivo.
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Affiliation(s)
- Vijay Sharma
- Molecular Imaging Center, Mallinckrodt Institute of Radiology and Department of Molecular Biology and Pharmacology, Washington University Medical School, St. Louis, Missouri 63110, USA
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332
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Bolzati C, Boschi A, Uccelli L, Tisato F, Refosco F, Cagnolini A, Duatti A, Prakash S, Bandoli G, Vittadini A. Chemistry of the strong electrophilic metal fragment [(99)Tc(N)(PXP)](2+) (PXP = diphosphine ligand). A novel tool for the selective labeling of small molecules. J Am Chem Soc 2002; 124:11468-79. [PMID: 12236761 DOI: 10.1021/ja0200239] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Monosubstituted [M(N)Cl(2)(POP)] [M = Tc, 1; Re, 2] and [M(N)Cl(2)(PNP)] [M = Tc, 3; Re, 4] complexes were prepared by reaction of the precursors [M(N)Cl(4)](-) and [M(N)Cl(2)(PPh(3))(2)] (M = Tc, Re) with the diphosphine ligands bis(2-diphenylphosphinoethyl)ether (POP) and bis(2-diphenylphosphinoethyl)methoxyethylamine (PNP) in refluxing dichloromethane/methanol solutions. In these compounds, the diphosphine acted as a chelating ligand bound to the metal center through the two phosphorus atoms. Considering also the weak interaction of the heteroatom (N or O) located in the middle of the carbon backbone connecting the two P atoms, we found that the coordination arrangement of the diphosphine ligand could be viewed as either meridional (m) or facial (f), and the resulting geometry as pseudooctahedral. The heteroatom of the diphosphine ligand was invariably located trans to the nitrido linkage, as established by X-ray diffraction analysis of the representative compounds 2m and 4f. Density functional theoretical calculations showed that in POP-type complexes the mer form is favored by approximately 6 kcal mol(-1), whereas mer and fac isomers are almost isoenergetic in PNP-type complexes. A possible role of noncovalent interactions between the phosphinic phenyl substituents in stabilizing the fac-isomer was also highlighted. The existence of fac-mer isomerism in this class of complexes was attributed to the strong tendency of the two phosphorus atoms to occupy a reciprocal trans-position within the pseudooctahedral geometry. The switching of P atoms between cis- and trans-configurations was confirmed by the observation that the fac isomers, 1f and 2f, were irreversibly transformed, in solution, into the corresponding mer isomers, 1m and 2m, thus suggesting that fac complexes are more reactive species. Theoretical calculations supported this view by showing that the lowest unoccupied orbitals of the fac isomers are more accessible to a nucleophilic attack with respect to those of the mer ones. Furthermore, the large participation of the Cl orbitals to the HOMO, which is a metal-ligand pi* antibonding in the complex basal plane, shows that the Tc-Cl bonds are labile. As a consequence, facial isomers could be considered as highly electrophilic intermediates that were selectively reactive toward substitution by electron-rich donor ligands. Experimental evidence was in close agreement with this description. It was found that fac-[M(N)Cl(2)(PXP)] complexes easily underwent ligand-exchange reactions with bidentate donor ligands such as mercaptoacetic acid (NaHL(1)), S-methyl 2-methyldithiocarbazate (H(2)L(2)), diethyldithiocarbamate sodium salt (NaL(3)), and N-acetyl-L-cysteine (H(2)L(4)) to afford stable asymmetrical heterocomplexes of the type fac-[M(N)(L(n))(POP)](+/0) (5-8) and fac-[M(N)(L(n))(PNP)](+/0) (9-14) comprising two different polydentate chelating ligands bound to the same metal center. In these reactions, the bidentate ligand replaced the two chloride atoms on the equatorial plane of the distorted octahedron, leaving the starting fac-[M(N)(PXP)](2+) (X = O, N) moieties untouched. No formation of the corresponding symmetrical complexes containing two identical bidentate ligands was detected over a broad range of experimental conditions. Solution-state NMR studies confirmed that the structure in solution of these heterocomplexes was identical to that established in the solid state by X-ray diffraction analysis of the prototype complexes fac-[M(N)(HL(2))(POP)][BF(4)] [M = Tc, 7; Re, 8] and fac-[Tc(N)(HL(2))(PNP)][BF(4)], 11. In conclusion, the novel metal fragment fac-[M(N)(PXP)](2+) could be utilized as an efficient synthon for the preparation of a large class of asymmetrical, nitrido heterocomplexes incorporating a particular diphosphine ligand and a variety of bidentate chelating molecules.
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Chryssou K, Pelecanou M, Pirmettis IC, Papadopoulos MS, Raptopoulou C, Terzis A, Chiotellis E, Stassinopoulou CI. New oxorhenium(V) complexes from the widely used diaminedithiol (DADT) ligand system. Inorg Chem 2002; 41:4653-63. [PMID: 12206688 DOI: 10.1021/ic020247s] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Synthesis of the 2,9-dimethyl-4,7-diaza-4-alkyl-2,9-decanedithiol (1, alkyl = morpholinylethyl in a, and alkyl = pyrrolidinylethyl in b), following a widely used synthetic scheme for diaminedithiol (DADT) ligands, led to the isolation of 1-alkyl-2-(1'-methyl-1'-sulfanylethyl)-3-(2' '-methyl-2' '-sulfanylpropyl)diazolidine (3) as the major product. Both ligands 1 and 2 gave complexes with the oxorhenium ReO(V) core. Ligand 1 gave the expected ReO[SNNS] complex (2) with the side chain on nitrogen in the syn configuration. Ligand 3 gave, in the presence of a monodentate aromatic thiol, complexes of the ReO[SNN][S][S] (4) and ReO[SNN][S] type (5), respectively, in which the diazolidine ring has rearranged to a thiazolidine ring. Crystallographic analysis showed that in 4 the coordination geometry about the metal is distorted octahedral where the equatorial plane is defined by the sulfur and one of the nitrogen atoms of the ligand and the two sulfurs of the aromatic thiols, while the axial positions are occupied by the oxygen of the ReO core and the second nitrogen of the ligand. Specifically, complex 4a crystallizes in space group P2(1)/c, a = 15.63(1) A, b = 15.28(2) A, c = 16.07(1) A, beta = 113.78(2) degrees, V = 3512(5) A(3), Z = 4. Complex 4b crystallizes in space group P2(1)/n, a = 14.560(9) A, b = 14.804(9) A, c = 19.85(1) A, beta = 90.94(2) degrees, V = 4278(1) A(3), Z = 4. In 5b, the coordination geometry is distorted square pyramidal with the SNN donor atom of the ligand and the aromatic thiol defining the equatorial plane and the doubly bonded oxygen occupying the apex of the pyramid. Complex 5b crystallizes in space group P(-)1, a = 9.387(5) A, b = 11.306(5) A, c = 14.040(6) A, alpha = 84.51(1) degrees, beta = 84.45(2) degrees, gamma = 87.17(1) degrees, V = 1475(1) A(3), Z = 2. All isolated complexes are neutral and lipophilic. Complete assignments of (1)H and (13)C NMR resonances are reported.
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Affiliation(s)
- Katerina Chryssou
- Institute of Biology, Demokritos National Centre for Scientific Research, Athens 15310, Greece
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Aly AA, Strasser A, Vogler A. Synthesis and spectroscopic properties of (oxytetracycline)tricarbonylrhenium(I) chloride. Inorganica Chim Acta 2002. [DOI: 10.1016/s0020-1693(02)00872-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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336
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La Bella R, Garcia-Garayoa E, Langer M, Bläuenstein P, Beck-Sickinger AG, Schubiger PA. In vitro and in vivo evaluation of a 99mTc(I)-labeled bombesin analogue for imaging of gastrin releasing peptide receptor-positive tumors. Nucl Med Biol 2002; 29:553-60. [PMID: 12088725 DOI: 10.1016/s0969-8051(02)00314-1] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
A new radiolabeled bombesin analogue, [99mTc(I)-PADA-AVA]bombesin (7-14), was synthesized and in vitro and in vivo characterized. High affinity and rapid internalization were obtained in binding assays. A specific binding towards gastrin releasing peptide receptors-positive tissues, pancreas and tumor, was observed in CD-1 nu/nu mice bearing PC-3 prostate adenocarcinoma xenografts. We therefore conclude that [99mTc(I)-PADA-AVA]bombesin (7-14) might have promising characteristics for applications in nuclear medicine, namely for diagnosis of GRP receptor overexpressing tumors.
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Affiliation(s)
- Roberto La Bella
- Center for Radiopharmaceutical Science, Paul Scherrer Institute, CH-5232 Villigen, Switzerland.
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337
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Zhang J, Vittal JJ, Henderson W, Wheaton JR, Hall IH, Hor T, Yan YK. Tricarbonylrhenium(I) complexes of phosphine-derivatized amines, amino acids and a model peptide: structures, solution behavior and cytotoxicity. J Organomet Chem 2002. [DOI: 10.1016/s0022-328x(02)01200-7] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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338
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Mévellec F, Lepareur N, Roucoux A, Noiret N, Patin H, Bandoli G, Porchia M, Tisato F. Chelated hydrazido(3-)rhenium(V) complexes: on the way to the nitrido-M(V) core (M = Tc, Re). Inorg Chem 2002; 41:1591-7. [PMID: 11896729 DOI: 10.1021/ic0110979] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Neutral and asymmetrical hydrazido(3-)rhenium(V) heterocomplexes of the type [Re(eta(2)-L(4))(L(n))(PPh(3))] (eta(2)-L(4) = NNC(SCH(3))S; H(2)L(1) = S-methyl beta-N-((2-hydroxyphenyl)ethylidene)dithiocarbazate, 1, H(2)L(2) = S-methyl beta-N-((2-hydroxyphenyl)methylidene)dithiocarbazate, 2) are prepared via ligand-exchange reactions in ethanolic solutions starting from [Re(V)(O)Cl(4)](-) in the presence of PPh(3) or from [Re(V)(O)Cl(3)(PPh(3))(2)]. The distorted octahedral coordination sphere of these compounds is saturated by a chelated hydrazido group, a facially ligated ONS Schiff base, and PPh(3). Reduction-substitution reactions starting from [NH(4)][Re(VII)O(4)] in acidic ethanolic mixtures containing PPh(3) and H(2)L(n) (or its dithiocarbazic acid precursor H(3)L(4)) produce another example of chelated hydrazido(3-) rhenium(V) derivative, namely [Re(eta(2)-L(4))Cl(2)(PPh(3))(2)], 3. On the contrary, the N-methyl-substituted dithiocarbazic acid H(2)L(3) reacts with perrhenate to give the known nitrido complex [Re(N)Cl(2)(PPh(3))(2)]. Rhenium(V) complexes incorporating the robust eta(2)-hydrazido moiety represent key intermediates helpful for the comprehension of the reaction pathway which generates nitridorhenium(V) species starting from oxo precursors. An essential requirement for the stabilization of such chelated hydrazido-Re(V) units is the triple deprotonation at the hydrazine nitrogens, thereby providing efficient pi-electron circulation in the resulting five-membered ring. The thermal stability of these units is affected by the nature of the anchoring donor, thione sulfur ensuring stronger chelation than nitrogen and oxygen. The eta(2)-hydrazido complexes are characterized by conventional physicochemical techniques, including the X-ray crystal structure determination of 1 and 3.
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Affiliation(s)
- Franck Mévellec
- Laboratoire de Chimie des Biomolécules et des Systèmes Organisés, CNRS UMR 6052, Ecole Nationale Supérieure de Chimie de Rennes (ENSCR), 35700 Rennes, France
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339
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Bergmann R, Scheunemann M, Heichert C, Mäding P, Wittrisch H, Kretzschmar M, Rodig H, Tourwé D, Iterbeke K, Chavatte K, Zips D, Reubi JC, Johannsen B. Biodistribution and catabolism of (18)F-labeled neurotensin(8-13) analogs. Nucl Med Biol 2002; 29:61-72. [PMID: 11786277 DOI: 10.1016/s0969-8051(01)00284-0] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
4-([(18)F]fluoro)benzoyl-neurotensin(8-13) ((18)FB-Arg(8)-Arg(9)-Pro(10)-Tyr(11)- Ile(12)-Leu(13)-OH, 1) and two analogs stabilized in one and two positions ((18)FB-Arg(8)psi(CH(2)NH)Arg(9)-Pro(10)-Tyr(11)- Ile(12)-Leu(13)-OH, 2, (18)FB-Arg(8)psi(CH(2)NH)Arg(9)-Pro(10)-Tyr(11)-Tle(12)-Leu(13)-OH, 3) were synthesized in a radiochemical yield of 25-36% and a specific activity of 5-15 GBq/mmol. The peptides were evaluated in vitro and in vivo for their potential to image tumors overexpressing neurotensin receptor 1 (NTR1) by positron emission tomography (PET). All analogs exhibited in vitro binding affinity in the low nanomolar range to NTR1-expressing human tumors, measured by quantitative receptor autoradiography, HT-29 and WiDr cells, and to sections of tumors derived from these cell lines in mice. The radiotracers were internalized in the cells in vitro, and the fluorinated peptides were able to mobilize intracellular Ca(2+) of WiDr cells. In in vivo studies in rats and in mice bearing HT-29 cell tumors, only a moderate uptake of the radioligands into the studied tumors was observed, presumed to be due to degradation in vivo and fast elimination by the kidneys. In comparison with the other analogs, the specific tumor uptake expressed as tumor-to-muscle relation was highest for the radioligand 3. The blood clearance of 3 was reduced by co-injection of peptidase inhibitors. The catabolic pathways of the radiofluorinated peptides were elucidated. The results suggest that the high binding affinity to NTR1 and the stabilization against proteolytic degradation are not yet sufficient for tumor imaging by PET.
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Affiliation(s)
- Ralf Bergmann
- Institut fuer Bioanorganische und Radiopharmazeutische Chemie, Forschungszentrum Rossendorf, Germany
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340
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Alves S, Paulo A, Correia JDG, Domingos Â, Santos I. Coordination capabilities of pyrazolyl containing ligands towards the fac-[Re(CO)3]+ moiety. ACTA ACUST UNITED AC 2002. [DOI: 10.1039/b207164a] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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341
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Woods M, Kovacs Z, Sherry A. Targeted Complexes of Lanthanide(III) Ions as Therapeutic and Diagnostic Pharmaceuticals. ACTA ACUST UNITED AC 2002. [DOI: 10.1016/s1472-7862(02)00072-2] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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342
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Kothari KK, Gali H, Prabhu KR, Pillarsetty N, Owen NK, Katti KV, Hoffman TJ, Volkert WA. Synthesis and characterization of (99m)Tc- and (188)Re-complexes with a diamido-dihydroxymethylenephosphine-based bifunctional chelating agent (N(2)P(2)-BFCA). Nucl Med Biol 2002; 29:83-9. [PMID: 11786279 DOI: 10.1016/s0969-8051(01)00280-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A diamido-dihydroxymethylenephosphine (N(2)P(2)) bifunction chelating agent (BFCA) was shown to form well-defined (99m)Tc- and (188)Re-chelate structures. The 4, 4-bis [bis-hydroxymethyl-phosphonyl-propylcarbonmoyl]-butyric acid bifunctional chelating agent (N(2)P(2)-BFCA) formed stable complexes with (99m)Tc and (188)Re in >95% yield with high radiochemical purity (RCP). The biodistribution of the (99m)Tc- and (188)Re-N(2)P(2)-BFCAs after intravenous injection studied in normal mice showed the activity was excreted primarily via renal-urinary pathway indicating their use for labeling peptides with (99m)Tc and (188)Re.
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Affiliation(s)
- K K Kothari
- Radiopharmaceuticals Division, Bhabha Atomic Research Center, Mumbai, India.
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343
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344
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Valliant JF, Riddoch R, Hughes DW, Roe DG, Fauconnier TK, Thornback JR. The solid phase synthesis and NMR spectroscopy of a 99Tc chelate–bombesin derived peptide conjugate. Inorganica Chim Acta 2001. [DOI: 10.1016/s0020-1693(01)00637-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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345
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Tisato F, Refosco F, Porchia M, Bandoli G, Pilloni G, Uccelli L, Boschi A, Duatti A. Technetium and rhenium heterocomplexes containing the diphenylphosphinoferrocenyl fragment. J Organomet Chem 2001. [DOI: 10.1016/s0022-328x(01)00917-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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346
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Gali H, Sieckman GL, Hoffman TJ, Owen NK, Chin DT, Forte LR, Volkert WA. In vivo evaluation of an 111In-labeled ST-peptide analog for specific-targeting of human colon cancers. Nucl Med Biol 2001; 28:903-9. [PMID: 11711309 DOI: 10.1016/s0969-8051(01)00276-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In vitro competitive binding studies of In-DOTA-NCS-6-Ahx-Phe(19)-ST[1-19] vs. 125I-Tyr(5)-6-Ahx-Phe(19)-ST[1-19] with guanylate cyclase -C (GC-C) receptors on human colon cancer LS-180 cells revealed an IC(50) value of 7.7 +/- 0.1.6 nM. The in vitro cellular residualization studies of the 111In-DOTA-NCS-ST peptide and GC-C receptor mediated stimulated cGMP production with LS-180 cells demonstrates that this peptide selectively binds to LS-180 cells in an agonistic fashion. In vivo biodistribution studies in LS-180 tumor bearing SCID mice demonstrates that the 111In-DOTA-NCS-ST peptide targets the tumor with a specific uptake of 0.94 +/- 0.31%ID/g at 1 hr p.i. and approximately 23% was retained by the tumor at 4 hrs p.i. The radioactivity cleared rapidly from the blood stream with 84.5 +/- 3.4%ID at 1h p.i. found in the urine. High activity in urine and kidney, and minimal activity in liver and intestines, demonstrates preferential clearance of the radioactivity through the renal/urinary pathway. The specific in vitro and in vivo accumulation of the radioactivity by LS-180 human colonic cancer cells highlights the potential of radiometallated-DOTA-ST analogs as diagnostic/therapeutic radiopharmaceuticals.
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Affiliation(s)
- H Gali
- Department of Radiology, University of Missouri-Columbia, Columbia, MO 65211, USA
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347
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Murugesa S, Shetty SJ, Srivastava TS, Noronha OP, Samuel AM. A technetium-99m-labelled cyclam acid porphyrin (CAP) for tumour imaging. Appl Radiat Isot 2001; 55:641-6. [PMID: 11573797 DOI: 10.1016/s0969-8043(01)00113-0] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A new water-soluble cyclam acid porphyrin (CAP), 5,10,15,20-tetrakis [4-[4',8',11'-tris(carboxymethyl)-1'-(1',4',8',11'-tetraazacyclotetradecane)amidomethyleneoxy]phenyl] porphyrin has been synthesised, characterised and labelled with 99mTc. In vivo distribution studies were performed in C6-gliomas and N-nitroso-N-methylurea (NMU) induced mammary tumour bearing rats and scintiimages were obtained at 5 h post-administration of the labelled ligand using gamma camera computer system. Tumour to muscle (T/M) ratios were determined and compared with currently available tumour seeking radiopharmaceuticals such as 99mTc(V)-DMSA, 99mTc-Citrate and 201TlCl. In the case of NMU induced mammary tumour rats the ratios were 6.93, 1.97, 5.30 and 3.29; while in the case of C6-gliomas the ratios were 5.58, 2.18, 3.96 and 3.02 for 99mTc-CAP, 99mTc(V)-DMSA, 99mTc-Citrate and 203TlCl, respectively.
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Affiliation(s)
- S Murugesa
- Radiation Medicine Centre, Tata Memorial Hospital Annexe, Parel, Mumbai, India.
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348
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Wong E, Bennett S, Lawrence B, Fauconnier T, Lu LF, Bell RA, Thornback JR, Eshima D. Tuftsin receptor-binding peptide labeled with technetium: chemistry and preliminary in vitro receptor-binding study. Inorg Chem 2001; 40:5695-700. [PMID: 11599972 DOI: 10.1021/ic010462t] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- E Wong
- Department of Chemistry, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada, L8S 4M1, Canada.
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349
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Abstract
The past several years have seen marked advances in technetium/rhenium chemistry applicable to the preparation of new 99mTc-labeled radiopharmaceuticals. This article focuses on recent developments in technetium chemistry, including the preparation of "3 + 1" complexes, the preparation and use of (99mTc[CO]3)+ complexes for labeling biomolecules, the preparation of rhenium steroid inclusion complexes, improvements in both hydrazinonicotinamide labeling chemistry and in the preformed 99mTc complex method of labeling biomolecules, and new solid-phase separation techniques that may allow the isolation of high specific-activity radiopharmaceuticals in a clinical setting.
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Affiliation(s)
- R C Mease
- Department of Diagnostic Radiology, University of Maryland School of Medicine, Baltimore 21201, USA
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350
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Rossin R, Blok D, Visentin R, Feitsma RI, Giron MC, Pauwels EK, Mazzi U. 99mTc-labeling experiments on CCK(4) by a direct method. Nucl Med Biol 2001; 28:865-73. [PMID: 11578909 DOI: 10.1016/s0969-8051(01)00254-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
99mTc-labeling studies have been performed on CCK(4) fragment of cholecystokinin, starting from 99mTc-pertechnetate, by using tin(II)pyrophosphate or tin(II)gluconate as reducing agents, together with NaBH(4) acting as a stabilizing agent of tin(II). Gluconate has been used as exchange ligand in the carrier added experiments and in the syntheses of 99Tc-CCK(4) and Re-CCK(4) complexes to be able to reproduce at macroscopic level the same chemical reactions occurring at non carrier added conditions. 99mTc-labeling yields higher than 95% have been achieved depending on Sn(II) concentration, CCK(4)/gluconate ratio, reaction time and applied temperature. The species produced with 99mTc, 99Tc, and cold rhenium nuclides have been compared by means of HPLC measurements, which showed similar retention times and thus probably the same species in the three situations.
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Affiliation(s)
- R Rossin
- Department of Pharmaceutical Sciences, University of Padova, via F. Marzolo 5, 35131, Padova, Italy
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