A Study of Drug Content and Cell Cytotoxicity of Paclitaxel-eluting Stents Coated with Various Biopolymer / 의학물리

In this study, the paclitaxel eluting stent (PES) was prepared by coating a biliary stent with paclitaxel using various biopolymer such as poly (vinyl acetate) (PVAc), poly (lactic-co-glycolic acid) (PLGA), Silicone rubber for restenosis prevention in gastrointestinal disease by a dip-coating method. Drug contents of PES were increased as surface area of stent, concentration and molecular weight of coating polymer increase. In 1H-NMR specta, we know that drug did not change by confirming specific peaks of paclitaxel in PES. As shown in SEM image, PES prepared using various biopolymer is coated clearly and regularly except Silicone rubber coating polymer. In in vitro cell cytotoxicity test, bare stent showed low cytotoxic effect against CT-26 colon carcinoma cell line on 3 day. However, PES coated with PLGA 502H showed the highest cytotoxicity because PLGA 502H is biodegradable polymer and has less molecular weight than other coating polymer. These results suggest that PES coated various biopolymer can be prevented restenosis in gastrointestinal disease.

Detection of Transferrin Receptor Over-Expression in a Rodent Model of Myocardial Ischemia/Reperfusion Injury Using Novel 99mTc Transferrin Conjugates: A Pilot Study

BACKGROUND AND OBJECTIVES: Reperfusion of ischemic myocardium is necessary to salvage tissue from eventual death. However, new pathophysiological changes are initiated after reperfusion. The aim of this study was to investigate one of the mechanisms of ischemia/reperfusion (I/R) injury, and we focused on transferrin. MATERIALS AND METHODS: Male Spragre-Dawley (SD) rats were used for the I/R model. Myocardial ischemia was produced by occlusion of the left anterior descending coronary artery for 30 minutes. 99mTc Transferrin-Chitosan-hydrazino nicotinate hydrochloride (HYNIC) (Tfc) (/37 MBq/mL) was injected once after the reperfusion was finished. Autoradiography, hematoxylin and eosin (H & E) staining and determination of the tissue myeloperoxidase (MPO) activity were performed. RESULTS: Autoradiography showed remarkable 99mTc-Tfc uptake in the left ventricular myocardium at the reperfusion period from 0 to 1.5 hours, whereas no uptake was demonstrated at 3 hours. The uptake was increased again at 6 and 24 hours. Western blotting showed that the transferrin receptor (TfR) proteins were increased at 0 to 1.5 hours compared with that of the control; this expression of TfR disappeared at 3 hours, and it showed up for the second time at 6 and 24 hours. The MPO activity only at 24 hours was significantly higher than that of the control and those MPO activities at 0 to 6 hours (p=0.001). CONCLUSION: In the rodent model of 30 minutes occlusion and reperfusion, our study revealed, with using 99mTc-Tfc, that the TfR expression increased in the myocardium till 3 hours after reperfusion. TfR-mediated entry of iron into the cardiomyocytes may represent that this process plays a role in the I/R injury during the early reperfusion period.