Technetium-99m exchange labeling of sensitive molecules

Conference · Sun Jan 01 04:00:00 EST 1984 · J. Nucl. Med.; (United States)

OSTI ID:6854148

Kramer, A V; Epps, L A; Place, D A; Burns, H D; Zemyan, S E

Considerable interest hnas been shown by researchers in radiolabelling biologically interesting and often complex molecules with technetium-99m (Tc-99m) to detect and study various disease states in vivo. Examples of such molecules include enzymes, metabolic substrates such as glucose, ligands that bind to inter- and extracellular receptors, and monoclonal antibodies. Unfortunately many of these potentially useful compounds contain functional groups essential for maintaining biological activity which do not tolerate conventional Tc-99m labeling techniques that employ reducing conditions. The authors report on a new labeling technique which avoids having to expose sensitive target molecules to reducing agents. Moreover, the technique has the potential for being applied to a wide variety of biologically useful molecules. The method employs the concept of exchange labeling. A strong chelator which is covalently bound to the target molecule extracts the metal from a suitable labile Tc-99m complex in which the metal exists in a reduced oxidation state. The authors have found, for example, that the technetium(V) moiety in the no carrier added N-methyl N,N'-bis(2-hydroxyethyl)ethylenediamine complex is transferred quantitatively to functionalized, N,N '-bis(2-mercaptoethyl)ethylenediamine ligands within an hour at concentrations below l0/sup -6/M. The optimum choice of chelate, labile Tc-99m complex, and exchange conditions depends upon a variety of factors which are currently being studied and evaluated.

• Research Organization: The Johns Hopkins Medical Institutions, Baltimore, MD
• OSTI ID: 6854148
• Report Number(s): CONF-840619-
• Conference Information: Journal Name: J. Nucl. Med.; (United States) Journal Volume: 25:5
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400202 -- Isotope Effects
Isotope Exchange
& Isotope Separation
550601* -- Medicine-- Unsealed Radionuclides in Diagnostics
62 RADIOLOGY AND NUCLEAR MEDICINE
AMINES
ANTIBODIES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CHELATES
CHEMICAL PREPARATION
CHEMICAL REACTIONS
CHEMISTRY
COMPLEXES
ENZYMES
HOURS LIVING RADIOISOTOPES
IN VIVO
INTERMEDIATE MASS NUCLEI
ISOMERIC TRANSITION ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
LABELLING
LIGANDS
MEMBRANE PROTEINS
MOLECULES
MONOCLONAL ANTIBODIES
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
OXIDATION
PROTEINS
QUANTITY RATIO
RADIOCHEMISTRY
RADIOISOTOPES
RECEPTORS
REDUCING AGENTS
SYNTHESIS
TECHNETIUM 99
TECHNETIUM ISOTOPES
TRACER TECHNIQUES
YEARS LIVING RADIOISOTOPES