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A Functional Role for Intra-Axonal Protein Synthesis during Axonal Regeneration from Adult Sensory Neurons
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One of the most rapidly expanding areas is the development of peptide-based agents for targeted imaging. Metal and halogen radionuclides such as 64Cu, 89Zr, 99mTc, 111In, 18F, and 124I are most commonly used for the design of the agents. Typically, the metal ion coordination chemistry is straightforward and mild. However, it requires attachment of a rather bulky chelator to the vector molecule what may deteriorate the biological activity. Simple direct iodination has been used for decades introducing minor modification at tyrosine amino acid residue though demonstrating poor residualizing of the radioactive iodine catabolites in the cell. On the contrary hydrophilic complexes of radiometals stay trapped in the cell after the degradation of the internalized imaging agent. The incorporation of 18F can be accomplished by the conventional nucleophilic or electrophilic addition, or via prosthetic groups . However, the synthesis might be rather complex with harsh conditions and high macromolecule concentration. A novel method utilizing similarity of Al18F2+ with metal cations and thus possibility of coordination labelling chemistry has potential for kit type production like radiometals . The relatively long half-life (110 min) of 18F enables centralized production and distribution of either the radionuclide or prepared imaging agents to the satellite clinical centres. Most of the PET agents used in clinical studies are 18F-based. Nevertheless, the simpler labelling chemistry of 68Ga and its availability from the generator system which can be used even at distant and isolated medical centres make 68Ga more preferable.
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It is important as a chemical intermediate in the rubber industry, as a corrosion inhibitor, and in the synthesis of optical brighteners, crop protection agents, dyes and drugs.
Prospective of 68Ga-Radiopharmaceutical Development
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The most common and commercially available BFC comprise esters (-nitrophenyl, pentafluorophenyl, -hydroxysuccinimide, sulfo--hydroxysuccinimide), isothiocyanates, maleimides, hydrazides, α-haloamides for the reaction with nucleophilic functional groups (-NH2, -SH, -OH) of vector molecules and formation of amide, urea, thiourea, Schiff-base, or thioester bond . Methods have been developed for the conjugation with peptides by solid-phase peptide synthesis (SPPS) resulting in defined position and number of chelate moieties. The outcome of the conjugation in solution wherein peptides and proteins comprise several reactive sites is very often a mixture of bioconjugate molecules with various content of the chelator. Such heterogeneity may cause the interpretation ambiguity of the performance of such imaging agents. Regioselective conjugation to antibodies was achieved by enzymatic reaction with lysine and glutamine residues using bacterial and human tissue transglutaminase as catalysts .
The labelling with radiometals can be direct or chelator-mediated (tagged). The direct 68Ga-labelling of macromolecules is limited and applies to proteins (e.g. lactoferrin, transferrin, ferritin) designed by nature for iron binding thus utilizing chemistry similarity of Ga(III) and Fe(III) . The direct 68Ga-labelling and formation of low molecular weight complexes is commonly employed for the development of imaging agents for perfusion or for imaging of biological processes where the agent uptake is defined by its charge, lipophilicity, and size. Particulate agents can also be produced by the direct 68Ga-labelling either by co-precipitation (e.g. macroaggregated albumin) or by co-condensation (e.g. 68Ga-carbon nanoparticles) [-]. The chelator mediated 68Ga-labelling, requiring first synthesis of a bioconjugate comprising vector molecule and chelate moiety for the coordination of the radiometal ion, is the most common pathway of imaging agent design. The principle components of such agents are targeting vector, chelator, and radionuclide (Figure A). The modulation of pharmacokinetics, biodistribution, and stability can be achieved by the introduction of pharmacokinetic modifiers (PKM) such as hydrocarbon chain, polyethylene glycol (PEG), carbohydrate, and polypeptide chain. PKM may also serve as linker/spacer between the bulky chelate moiety and the active site of the vector molecule. Thermodynamic and kinetic stability, geometry and lipophilicity of a chelator-metal ion complex are important parameters in the development of radiometal based radiopharmaceuticals.
The Mammalian Ribo-interactome Reveals Ribosome …
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332. Ujula T, Salomaki S, Virsu P, Lankinen P, Makinen TJ, Autio A. . Synthesis, Ga-68 labeling and preliminary evaluation of DOTA peptide binding vascular adhesion protein-1: a potential PET imaging agent for diagnosing osteomyelitis. 2009;36:631-41
134. Knor S, Modlinger A, Poethko T, Schottelius M, Wester HJ, Kessler H. Synthesis of novel 1,4,7,10-tetraazacyclodecane-1,4,7,10-tetraacetic acid (DOTA) derivatives for chemoselective attachment to unprotected polyfunctionalized compounds. 2007;13:6082-90
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described in the Cell journal on 6 ..
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anti-aging products - Lucrece
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anti-aging peptides - Lucrece
Immunosuppressive Drugs for Kidney Transplantation …
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THE CANCER SOLUTION by Dr Robert E. Willner M.D., …
(2007)).Diseases related to C3a desArgregulation of the triglyceride synthesis, glucose transport, insulin regulationand fatty acid not yet been described.Precautions/Toxicity/HazardsThisprotein is purified from human serum and therefore precautions appropriate forhandling any blood-derived product must be used even though the source wasshown by certified tests to be negative for HBsAg, HTLV-I/II, STS, and forantibodies to HCV, HIV-1 and HIV-II.HazardCode: BWGK 3References, A.W.
1993 [word print version] DEDICATION..
It is most important as a chemical intermediate in the rubber industry, in corrosion control, and in the synthesis of a large number of drugs, crop protection agents, dyes and optical brighteners (Texaco, 1986; Heilen et al., 1989).
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