loop_ _pdbx_investigation_sample.sample_id _pdbx_investigation_sample.investigation_id _pdbx_investigation_sample.poly_descript_id _pdbx_investigation_sample.nonpoly_descript_id _pdbx_investigation_sample.descript_id 1 1 1 1 1 2 1 1 2 1 3 1 2 3 2 4 1 3 4 3