| PLS | Papillon-Lefevre syndrome; polydactyly-luxation syndrome; preleukemic syndrome; primary lateral scle... |
|---|---|
| PSDA | Patient Self-Determination Act; psychoactive substance abuse and dependence |
| RCS | rabbit aorta-contracting substance; red cell suspension; reticulum cell sarcoma; right coronary sinu... |
| RDS | Raskin Depression Scale; respiratory distress syndrome; reticuloendothelial depressing substance; rh... |
| Rf | in paper or thin-layer chromatography, the distance that a spot of a substance has moved from the po... |