['Inhibition of intercellular adhesion molecule-1 (ICAM-1) expression can ameliorate the inflammation induced by ischemia-reperfusion injury (IRI) in animal models. However, current strategies to reduce ICAM-1 expression have been limited by the lack of stability, poor specificity, and the transient nature of synthesized regulatory molecules (antisense/ribozyme).', 'A chimeric expression vector was generated by fusing a ribozyme targeting sequence against ICAM-1 to stabilizing stem-loop structures and nuclear localization signals that are components of endogenous U1 small nuclear RNA. Oligonucleotide scanning was used to predict accessible sites for targeting within the rat ICAM-1 transcript. Efficacy of the chimeric ribozyme vector was tested by transfection of rat aortic endothelial (RAE) cells (in vitro) and intraportal delivery in a rat hepatic IRI model (in vivo).', 'Transfection of RAE cells with the chimeric ribozyme vector produced potent and specific inhibition of ICAM-1 mRNA and protein levels by >65%. This reduction in ICAM-1 expression was accompanied by a proportional decrease in neutrophil adhesion to RAE cells. In vivo intraportal delivery of the chimeric targeting vector to rats sustaining hepatic IRI produced a marked reduction in ICAM-1 expression on liver endothelium after reperfusion.'] Does a novel chimeric ribozyme vector produce potent inhibition of ICAM-1 expression on ischemic vascular endothelium?