[Triumf-seminars] TRIUMF Seminar today at 14:00

postmaster at admin.triumf.ca postmaster at admin.triumf.ca
Wed Apr 15 05:00:01 PDT 2009


Date/Time: Wed 2009-04-15 at 14:00

Location:  Auditorium          

Speaker:   Paul Schaffer (General Electric)

Title:     Preclinical Radiotracer Development of Small and Large Molecular Weight Constructs

Abstract: Positron Emission Tomography (PET) and Single Photon Emission Computed Tomography (SPECT) are two critical imaging modalities within the molecular imaging regimen. The future of these imaging techniques relies heavily on the development of new agents that can target specific disease tissues. These radiotracers can be used in several different ways. They can play an important role in the early diagnosis of disease, allow stratification of patients to avoid unnecessary treatments for individuals who will not respond to a current therapeutic option, and serve as a means to monitor treatment response.

Radioisotope incorporation onto macromolecular constructs has been gaining momentum as the number of medical applications for these entities has grown. The natural affinity of peptides and proteins toward various tissues, coupled with their biological compatibility, give these constructs precedence in the move from small molecules to larger targeted compounds. We have demonstrated the radioisotope incorporation and post injection behavior of several peptide/protein scaffolds, ranging in size from 7 kDa to over 200 kDa. In vitro and in vivo model development, bioconjugation chemistry, radiochemistry, biodistribution and metabolism for one specific polypeptide scaffold will be discussed.

Due to their intracellular accessibility, small molecular weight vectors also play a critical role in radiotracer development. To this end, enantiomerically pure (+)-[11C]DTBZ and other DTBZ derivatives, have been widely used in neurological imaging as part of an effort to better understand such debilitating disorders as schizophrenia, Tourette’s syndrome, Parkinson’s, Huntington’s, and Alzheimer’s diseases, as well as the mechanism of narcotics addiction. Driven by this observation, radiolabelled DTBZ derivates have also been used to determine the role of the type 2 vesicular monoamine transporter (VMAT2) in the early stages of diabetes. Unfortunately, all procedures reporting DTBZ preparations to date require the use of enantiomeric resolution in order to produce optically pure DTBZ derivatives. We have established an asymmetric synthesis and radiolabelling protocol for a novel (+)-[18F]DTBZ analogue. The in vitro and in vivo behavior of the lead tracer was examined and established to bind specifically to the VMAT2 receptor. Suitability of this tracer for the early detection of diabetes will be discussed. 



Stimulants available 15 minutes before the talk.

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