A consensus Development Conference was held at the National Institutes of Health from September 29-October 1, 1980, to address issues concerning the role of carcinoembryonic antigen (CEA) as a marker in the management of cancer. The panel met following formal presentations and discussions to assess the issues based on the evidence presented. These issues included: Should CEA be used in cancer screening? Is CEA helpful in cancer diagnosis? What does CEA tell about the extent and outcome of cancer? Is CEA helpful in monitoring cancer treatment? This paper constitutes the panel's findings.
Molecular structural characteristics of thyroid hormones which influence binding to the erythrocyte membranes were investigated by competitive binding experiments. The ability of thyroid hormone analogs to displace 131 I-L-thyroxine and 131 I-L-triiodothyronine from the membranes was considered evidence of their competitive binding. The diphenyl ether linkage (thyronine) was essential as compounds with a single aromatic ring were weakly competitive. The presence of three iodine atoms at 3, 5 and 3' positions on thyronine was optimal for maximal competitive binding. There was weak competitive binding of analogs if chlorine or bromine was substituted for iodine. The alanine side chain was required for optimal binding as N-acetyl-l-thyroxine and various deaminated analogs were poor competitors compared to T4 and T3. L-isomers of T4 and T3 showed greater competitive binding to erythrocyte membranes than the corresponding d-isomers.
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