Dong Lyun Cho

The role of carbonaceous deposits in the skeletal isomerization of 1-butene over ferrierite zeolites

The inner pores of ferrierite (FER) with a Si/Al ratio of 21 have been modified by plasma-polymerized propylene loading and subsequent thermal treatment under a flow of He at 550°C in order to identify the exact role of carbonaceous deposits (coke) in the skeletal isomerization of 1-butene. It was found that even a small weight loading (0.8 wt%) of carbonaceous deposits within the inner pores of FER zeolite was sufficient to modify the pore structure of the zeolite, leading to a noticeable enhancement of the selectivity to isobutene. This may be attributed to the increased spatial constraints inside the pores which restrict undesired side reactions, such as 1-butene dimerization followed by cracking to light hydrocarbons.

Histopathological Comparison among Biolimus, Zotarolimus and Everolimus-Eluting Stents in Porcine Coronary Restenosis Model.

Background and Objectives The aim of this study was to examine the histolopathogical effects among the biolimus, zotarolimus, and everolimus eluting stent (EES) in the porcine coronary restenosis model. Subjects and Methods Pigs were randomized into three groups in which the coronary arteries (15 pigs, 10 coronaries in each group) had either a biolimus A9 eluting stent (BES, n=10), zotarolimus eluting stent (ZES, n=10) or an EES (n=10). Histopathologic analysis was performed at 28 days after stenting. Results There were no significant differences in the injury score among the three groups. There was a significant difference in the internal elastic lamina, lumen area, neointima area, percent area stenosis, and the fibrin and inflammation score among the three groups (4.3±0.53 mm2, 2.5±0.93 mm2, 1.8±1.03 mm2, 40.7±20.80%, 1.7±0.41, 1.4±0.72 in the BES group vs. 5.1±0.55 mm2, 2.3±1.14 mm2, 2.8±1.00 mm2, 55.4±21.23%, 2.0±0.39, 1.6±0.76 in the ZES group vs. 4.4±0.53 mm2, 1.7±1.22 mm2, 2.8±1.23 mm2, 64.0±26.00%, 1.8±0.76, 2.1±0.90 in the EES group, respectively). BES is more effective in inhibiting neointimal hyperplasia compared to ZES and EES (p<0.0001). According to the fibrin and inflammation score, BES and EES are more effective in decreasing the fibrin deposition compared to ZES (p<0.001). Moreover, BES and ZES are more effective in reducing the inflammatory reaction compared to EES (p<0.001). Conclusion The result demonstrates that BES shows better histopathological characteristics than ZES and EES at one month after stenting in the porcine coronary restenosis model.

The long-term clinical results of a platelet glycoprotein IIb/IIIa receptor blocker (Abciximab: Reopro) coated stent in patients with coronary artery disease.

Background : Previously, the inhibition of coronary restenosis with Abciximab (ReoPro®)-coated stent in a porcine model was reported. ReoPro® inhibits platelet aggregation, the proliferation of vascular smooth muscle cells and the inflammatory reaction. Methods : A prospective randomized trial was performed to compare two types of stent for revascularization in the native coronary artery. The primary effective end points were major adverse coronary events (MACE): cardiac death, acute myocardial infarction, target vessel revascularization (TVR) and restenosis at the 6-month clinical and angiographic follow-ups. Results : One hundred and fifty-five patients were enrolled between August 2001 and June 2003. The mean ages (56.0±10.0 vs. 56.9±10.8 years), baseline diameter of stenosis and minimal luminal diameter were no different between the two groups. There was one myocardial infarction and revascularization during the hospital stay in control stent group. During the clinical follow-up there were two myocardial infarctions in control group. Follow-up coronary angiograms were performed in 62.3% (48/77) and 65.4% (51/78) of the coated and control groups, respectively. The diameter of stenosis and late loss were significantly less in the ReoPro®-coated stent group compared with the controls (16.4±5.8% vs. 34.3±6.1%, p=0.009; and 0.33±0.28 mm vs. 0.88±0.41 mm; p=0.002). The restenosis and TVR rates of the ReoPro®-coated stent were relatively lower compared with the control stent [14.6% (7/48) vs. 29.4% (15/51), p=0.062; and 9.2% (7/76) vs. 14.7% (11/75); p=0.327]. Conclusion : A ReoPro®-coated stent is safe, and may be effective in the prevention of coronary restenosis.

Comparison of sirolimus loaded PLGA-PEG Co-polymer coronary stent and bare metal stent in a porcine coronary restenosis model

The aim of this study was to compare the effect of the sirolimus loaded PLGA-PEG co-polymer coronary stent with that of the bare metal stent in a porcine coronary restenosis model. Pigs were randomized into two groups (10 pigs, 10 coronary arteries in each group), in which either the sirolimus loaded PLGA-PEG copolymer stent (SPPS, n=10) or the bare metal stent (BMS, n=10) was implanted in the coronary arteries. Histopathologic analysis was performed at 28 days after stenting. There were no significant differences in the injury score, internal elastic lamina (IEL) area, and inflammation score between the two groups. There were significant differences in the lumen area (3.6±0.42 mm2 in the SPPS group vs. 2.5±0.89 mm2 in the BMS group, p<0.001), in the neointimal area (1.2±0.34 mm2 in the SPPS group vs. 2.5±0.99 mm2 in the BMS group, p<0.001), in the percent area stenosis (26.0±6.58% in the SPPS group vs. 48.6±16.95% in the BMS group, p<0.001) and in the fibrin score (1.2±0.41 in the SPPS group vs. 0.5±0.26 in the BMS group, p<0.001). These results demonstrate that SPPS had a superior effect on suppression of neointimal hyperplasia than BMS at one month after stenting in a porcine coronary restenosis model.

Effect of polymer-free TiO2 stent coated with abciximab or alpha lipoic acid in porcine coronary restenosis model.

BACKGROUND Polymer-free drug-eluting stents (DES) may overcome the shortcomings of polymer-based DES. The aim of this study was to examine the effect of the polymer-free TiO2 film-coated stent with abciximab or alpha lipoic acid in a porcine coronary overstretch restenosis model. METHODS Pigs were randomized into four groups in which the coronary arteries (24 pigs, 48 coronaries in each group) had TiO2 film-coated stent with abciximab (TCA, n = 12), TiO2 film-coated stent with alpha lipoic acid (TCALA, n = 12), biolimus A9-eluting stents with biodegradable polymer (BES, n = 12), and TiO2 film-coated stent (TCstent, n = 12). Histopathologic analysis was performed at 28 days after stenting. RESULTS There was no significant difference in the injury score and internal elastic lamina (IEL) among the four groups. There were significant differences in the lumen area, neointima area, percent area stenosis, fibrin score, and inflammation score among the four groups [2.7 ± 1.0mm(2), 2.6 ± 0.94 mm(2), 48.9 ± 16.25%, 1.0 (range 0.0-3.0), 1.0 (range 0.0-2.0) in TCA stent group vs. 2.7 ± 1.24 mm(2), 2.9 ± 0.83 mm(2), 53.5 ± 17.19%, 1.0 (range 0.0-2.0), 1.0 (range 0.0-2.0) in TCALA stent group vs. 2.7 ± 1.30 mm(2), 2.6 ± 1.06 mm(2), 50.1 ± 23.20%, 2.0 (range 1.0-3.0), 2.0 (range 1.0-3.0) in BES group vs. 1.7 ± 0.63 mm(2), 3.3 ± 0.58 mm(2), 60.2 ± 10.12%, 0.5 (range 0.0-2.0), 1.0 (range 0.0-2.0) in TC stent group, respectively]. CONCLUSION TCA and TCALA are more effective to reduce neointimal hyperplasia compared to TC. Moreover, fibrin and inflammation scores are significantly lower in TCA and TCALA than BES in porcine coronary restenosis model.

Novel abciximab-Kruppel-like factor 4-plasmid dual-delivery titanium dioxide-coated coronary stent

a Department of Cardiology, Chonnam National University Hospital, Gwangju, Republic of Korea b Heart Research Center, Chonnam National University Hospital, Gwangju, Republic of Korea c Department of Molecular Medicine and Advanced Chemical & Engineering, Chonnam National University Graduate School, Gwangju, Republic of Korea d Center for Functional Nano Fine Chemicals & School of Applied Chemical Engineering, Chonnam National University, Gwangju, Republic of Korea e Institute of Interventional Medicine, M.I. Tech Co., Ltd., Pyeongtaek, Republic of Korea

Effect of Atorvastatin-Eluting Stents in a Rabbit Iliac Artery Restenosis Model

Statins have pleiotropic effects, which include the inhibition of neointima hyperplasia, the inhibition of vascular inflammation, and platelet inhibition. The aim of this study was to examine the effect of an atorvastatin-eluting stent (AES) in a rabbit iliac artery overstretch restenosis model. Ten rabbits were used in this study (10 rabbits, 10 iliac arteries for each stent). An AES and paclitaxel-eluting stent (PES) were implanted in the left and right iliac arteries in a rabbit (2 stents in each rabbit). The stents were deployed with oversizing (stent/artery ratio 1.3:1), and histopathologic analysis was assessed at 28 days after stenting. There were no significant differences in the injury score, lumen area, or inflammation score. There were significant differences in the neointimal area (0.7±0.18 mm2 in the AES group vs. 0.4±0.25 mm2 in the PES group, p<0.01), in the percentage stenosis area (14.8±5.06% in the AES group vs. 10.5±6.80% in the PES group, p<0.05), and in the fibrin score (0.4±0.51 in the AES group vs. 2.7±0.48 in the PES group, p<0.001). Although the AES did not suppress neointimal hyperplasia compared with the PES, it showed a superior arterial healing effect in a rabbit iliac artery overstretch restenosis model.

Development of Blood Compatible Alpha-lipoic acid Coated Stent with a Good Adhesive by Low Temperature Plasma Polymerization

Neointimal hyperplasia is a main cause for in-stent restenosis after stent-implantation and is triggered by inflammatory response to foreign materials. It can be inhibited if the stent is modified to have good blood compatibility by coating drug compounds. Low temperature plasma polymerization of 1, 2-diaminocyclohexane was performed to prepare more adhesive polymeric thin film onto the metallic stent. Then, the chemical grafting of α-lipoic acid (ALA) was carried out to improve blood compatibility of stent. Drugs containing carboxylic groups can be chemically grafted through the formation of amide bond in the presence of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide methiodide onto the DACH deposited stent surface. ALA grafted film showed good mechanical stability and blood compatibility.