Byungjun Kim

Characteristics of felodipine-located poly(ε-caprolactone) microspheres

Felodipine-loaded poly (ε-caprolactone) (PCL) microspheres were prepared by two methods, the conventional emulsion solvent evapouration method and the quenching method. The aim of this work was to investigate the effects of process parameters such as emulsion type, drug loading, molecular-weight of the polymer, types of emulsion stabilizer and dispersed phase solvents, as well as preparation methods. The results show that, when conventional emulsion solvent evapouration method was used, the o/w-method produced smaller mean size and higher encapsulation efficiency compared with the o/o-method. The encapsulation efficiencies increased with an increase in the molecular weight and a decrease in crystallinity of PCL. The size of microspheres varied with the type of emulsion stabilizer used, smaller microspheres with PVA and narrow size distribution with Pol 237. The water solubility of the dispersed phase solvent was one of the critical factors in controlling the encapsulation efficiency and microsphere mean size. When water-soluble solvents such as acetonitrile and ethyl formate were used, the encapsulation efficiencies decreased due to higher evapouration rate. When quenching methods were used, in contrast to the conventional emulsion solvent evapouration method, very narrowly size-distributed but bigger microspheres were obtained.

Thromboembolic Complications in Patients with Clopidogrel Resistance after Coil Embolization for Unruptured Intracranial Aneurysms

BACKGROUND AND PURPOSE: Antiplatelet resistance is known to be associated with symptomatic ischemic complication after endovascular coil embolization. The purpose of our study was to evaluate the relationship between antiplatelet resistance and clinically silent thromboembolic complications using DWI in patients who underwent coil embolization for unruptured intracranial aneurysm. MATERIALS AND METHODS: Between October 2011 and May 2013, 58 patients with 62 unruptured aneurysms who were measured for antiplatelet response using VerifyNow assay and underwent elective coil embolization for an unruptured aneurysm with posttreatment DWI were enrolled. Diffusion-positive lesions were classified into 3 groups according to the number of lesions (n = 0 [grade 0], n < 6 [grade I], and n ≥ 6 [grade II]). The relationship between antiplatelet resistance and diffusion-positive lesions was analyzed. RESULTS: Sixty-two endovascular coiling procedures were performed on 58 patients. Clopidogrel resistance was revealed in 23 patients (39.7%) and diffusion-positive lesions were demonstrated in 28 patients (48.3%); these consisted of 19 (32.8%) grade I and 9 (15.5%) grade II lesions. Clopidogrel resistance was not relevant to the development of any diffusion-positive lesion (grade I and II, P = .789) but was associated with the development of multiple diffusion-positive lesions (grade II, P = .002). In the logistic regression prediction model, clopidogrel resistance showed significant correlation with the development of grade II lesions (P = .001). CONCLUSIONS: Multiple diffusion-positive lesions (≥6 in number) occurred more frequently in patients with clopidogrel resistance after endovascular coiling for unruptured aneurysms.

Preparation of low-fat uptake doughnut by dry particle coating technique

Soybean hull-wheat flour composites were prepared and used a doughnut formulation in order to decrease fat uptake during deep-fat frying. Soybean hulls were microparticulated by jet milling, and wheat flour was air-classified into coarse and fine fraction by an air classifying system. The coarse fraction of wheat flour was dry-coated with the microparticulated soybean hulls by a hybridization system. To investigate the effect on fat uptake, 4 different types of composites were prepared, which contained 0%, 1%, 5%, and 10% of soybean hulls. Doughnuts containing 1%, 5%, and 10% of microparticulated hulls decreased fat contents of 11.5%, 13.6%, and 35.8%, respectively. As soybean hulls content increased, hardness and crispiness increased. However, sensory evaluations demonstrated that there were no significant differences in appearance, flavor, crispiness, taste, and general liking (P < 0.05). Inner crust structures of doughnut showed slight reductions in cell size and improved cellular integrity with shrinkage in the cell membrane as the content of soybean hulls increased. These results show that microparticulated soybean hulls may form a protective layer during frying process, and this process could be used by the food industry for preparing doughnuts with reduced fat uptake.

Endovascular treatment of unruptured ophthalmic artery aneurysms: clinical usefulness of the balloon occlusion test in predicting vision outcomes after coil embolization

Background Endovascular coil embolization for ophthalmic artery (OphA) aneurysms has the latent risk of occlusion of the OphA during the procedure, which can lead to loss of vision. We report clinical and angiographic results of endovascular treatment of OphA aneurysms together with the efficacy of the balloon occlusion test (BOT). Methods From August 2005 to December 2013, 31 consecutive patients with 33 OphA aneurysms were treated in our institution. The patients were classified into two groups according to the location of the OphA within the aneurysmal sac. The BOT was performed in 28 patients using a hypercompliant balloon before endovascular coiling. Collateral circulation between the external carotid artery and the OphA was examined and visual function tests were performed before and after treatment. Patient demographics, angiographic and clinical outcomes were reviewed. Results Among the 28 patients who underwent the BOT, intact collateral circulation was demonstrated in 26 (92.9%) patients and complete occlusion of the OphA was obtained in three patients after coiling. Retrograde filling of the OphA with choroidoretinal blush was observed on post-procedural angiography and no specific visual symptoms were reported during the follow-up period. Complete embolization was achieved in 30 lesions (96.8%) and only five patients (16.1%) had minor recanalization. Conclusions Endovascular treatment of OphA aneurysms can be performed safely and effectively in conjunction with BOT. The BOT may give useful information to predict visual outcome in patients whose OphA is likely to be threatened by the coiling procedure and to determine the optimal treatment strategy.

Rescue Stenting for Failed Mechanical Thrombectomy in Acute Ischemic Stroke: A Multicenter Experience

Background and Purpose— Effective rescue treatment has not yet been suggested in patients with mechanical thrombectomy (MT) failure. This study aimed to test whether rescue stenting (RS) improved clinical outcomes in MT-failed patients. Methods— This is a retrospective analysis of the cohorts of the 16 comprehensive stroke centers between September 2010 and December 2015. We identified the patients who underwent MT but failed to recanalize intracranial internal carotid artery or middle cerebral artery M1 occlusion. Patients were dichotomized into 2 groups: patients with RS and without RS after MT failure. Clinical and laboratory findings and outcomes were compared between the 2 groups. It was tested whether RS is associated with functional outcome. Results— MT failed in 148 (25.0%) of the 591 patients with internal carotid artery or middle cerebral artery M1 occlusion. Of these 148 patients, 48 received RS (RS group) and 100 were left without further treatment (no stenting group). Recanalization was successful in 64.6% (31 of 48 patients) of RS group. Compared with no stenting group, RS group showed a significantly higher rate of good outcome (modified Rankin Scale score, 0–2; 39.6% versus 22.0%; P=0.031) without increasing symptomatic intracranial hemorrhage (16.7% versus 20.0%; P=0.823) or mortality (12.5% versus 19.0%; P=0.360). Of the RS group, patients who had recanalization success had 54.8% of good outcome, which is comparable to that (55.4%) of recanalization success group with MT. RS remained independently associated with good outcome after adjustment of other factors (odds ratio, 3.393; 95% confidence interval, 1.192–9.655; P=0.022). Follow-up vascular imaging was available in the 23 (74.2%) of 31 patients with recanalization success with RS. The stent was patent in 20 (87.0%) of the 23 patients. Glycoprotein IIb/IIIa inhibitor was significantly associated with stent patency but not with symptomatic intracranial hemorrhage. Conclusions— RS was independently associated with good outcomes without increasing symptomatic intracranial hemorrhage or mortality. RS seemed considered in MT-failed internal carotid artery or middle cerebral artery M1 occlusion.

Consensus Statements by Korean Society of Interventional Neuroradiology and Korean Stroke Society: Hyperacute Endovascular Treatment Workflow to Reduce Door-to-Reperfusion Time

Recent clinical trials demonstrated the clinical benefit of endovascular treatment (EVT) in patients with acute ischemic stroke due to large vessel occlusion. These trials confirmed that good outcome after EVT depends on the time interval from symptom onset to reperfusion and that in-hospital delay leads to poor clinical outcome. However, there has been no universally accepted in-hospital workflow and performance benchmark for rapid reperfusion. Additionally, wide variety in workflow for EVT is present between each stroke centers. In this consensus statement, Korean Society of Interventional Neuroradiology and Korean Stroke Society Joint Task Force Team propose a standard workflow to reduce door-to-reperfusion time for stroke patients eligible for EVT. This includes early stroke identification and pre-hospital notification to stroke team of receiving hospital in pre-hospital phase, the transfer of stroke patients from door of the emergency department to computed tomography (CT) room, warming call to neurointervention (NI) team for EVT candidate prior to imaging, NI team preparation in parallel with thrombolysis, direct transportation from CT room to angiography suite following immediate decision of EVT and standardized procedure for rapid reperfusion. Implementation of optimized workflow will improve stroke time process metrics and clinical outcome of the patient treated with EVT.