L. Washburn, T. T. Sun, B. Byrd
Aug 1, 1979
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Influential Citations
31
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Journal
Journal of Computer Assisted Tomography
Abstract
In animal studies, DL-[carboxyl-14C]tryptophan [DL-Try(C-14)] showed a high specificity for the pancreas, which suggested the potential of DL-[carboxyl-11C]tryptophan [DL-Try(C-11)] for clinical pancreatic inaging. The blood clearance and tissue uptake of the amino acid were very rapid, and no carrier effect was observed through a dose of 5 mg/kg. None of three transplanted hamster pancreatic adenocarcinomas that we studied showed a selective uptake of DL-Try(C-14) by the tumor, and none of the three enzymatic regimens investigated gave significant enhancement of the pancreatic specificity. Commercial L-Try(C-14) gave slightly better pancreatic specificity than the analogous racemic compound but without enough improvement to warrant attempts at optical resolution. DL-Try(C-11) was synthesized in amounts up to 325 mCi using a rapid, high-temperature, high-pressure modification of the Bücherer-Strecker amino acid synthesis. Yields ranged from 30--60%, and a total of 40 min was required for synthesis and chromatographic purification. DL-Try(C-11) thus appears to have significant potential as a clinical pancreas-imaging agent, particularly when used in conjunction with positron computerized transaxial tomography.