Si-Yeol Kim

The Protection of the Retina from Ischemic Injury by the Free Radical Scavenger EGb 761 and Zinc in the Cat Retina

We investigated the effects of a free radical scavenger (EGb 761) and zinc in experimentally induced ischemic injury in the cat retina. Total retinal ischemia for 90 min was produced in the left eyes of 40 cats by raising intraocular pressure. In group 1, 10 cats were used as control. The free radical scavenger (EGb 761, 100 mg/kg) in group 2 (10 cats) and zinc chloride (250 μg/kg) in group 3 (10 cats) were administered intravenously at the end of ischemia. In group 4, both EGb 761 (100 mg/kg) and zinc chloride (250 μg/kg) were injected into 10 cats. ERG and a histologic study were performed 1 h, 1 day, 3 days, 1 week and 2 weeks after ischemia. The amplitude of the ERG b-wave was 62.73±0.32, 84.31±6.10, 83.65±12.23 and 102.4±14.27%, and the summed amplitude of oscillatory potentials was 66.16±16.42, 99.44±14.92, 95.45±6.42 and 99.62±12.32% in each group 2 weeks after ischemia. There was no significant effect in animals that received zinc alone (group 3) by the end of 1 week but some additive effect in combining EGb 761 and zinc chloride (group 4) 1 h after ischemia. These findings suggest that the free radical scavenger EGb 761 may efficiently protect the retina from ischemic injury and zinc may have an additive effect when combined with a radical scavenger.

Changes of calretinin, calbindin D28K and parvalbumin-immunoreactive neurons in the superficial layers of the hamster superior colliculus following monocular enucleation

We studied the effects of monocular enucleation on the patterned distribution of calretinin-, calbindin D28K- and parvalbumin-immunoreactive (IR) neurons in the superficial layers of the hamster superior colliculus (SC). The calcium-binding proteins were localized using antibody immunocytochemistry. Almost complete depletion of the calretinin-IR fibers in the superficial layers of the contralateral SC was found following unilateral enucleation. Quantitative analysis showed that on the experimental side of the SC, an enormous number of calretinin-IR cells newly appeared (716%). On the experimental side of the SC, the number of parvalbumin-IR cells also increased (32%). By contrast, on the experimental side of the SC, the number of calbindin D28K-IR cells exhibited a reduction (43%). Two-color immunofluorescence revealed that none of the newly appeared calretinin-IR cells were labeled with antibodies to calbindin D28K or parvalbumin. The present results demonstrate that retinal projection may control the activity of the expression of these calcium-binding proteins in the hamster SC but in different manners. The results also show that the patterned change of calretinin and parvalbumin in the hamster SC is comparable with other animals, but the change of calbindin D28K is not identical.

A novel design of one-side coated biodegradable intrascleral implant for the sustained release of triamcinolone acetonide

The purpose of this study was to evaluate the efficacy and safety of biodegradable intrascleral implants for the slow release of triamcinolone acetonide (TA). Intrascleral implant (1 mm thick; 3 mm diameter) was made of PLA (poly(D,L-lactide)) containing 6.4 mg of TA with one-side coating of high molecular weight PLA to render unidirectional drug absorption through the sclera. In vitro TA release was evaluated by liquid chromatography-mass spectroscopy for 90 days. In vivo release of TA was measured in aqueous humor, vitreous, and retina-choroid at 1, 2, 4, 8, and 12 weeks after intrascleral implantation in 20 rabbit eyes. Implant toxicity and biocompatibility were evaluated by slit lamp examinations, indirect ophthalmoscopy, intraocular pressure measurements, electroretinography, and histological examinations. In vitro studies demonstrated that the implants released TA in a controlled manner over 90 days. In vivo, TA was detected in aqueous humor until 4 weeks and in retina-choroid until 8 weeks after implantation, but was detected constantly over 12 weeks in vitreous. No significant retinal toxicity was observed. These results suggest that the devised intrascleral implant offers a promising controlled release system for the delivery of TA to the posterior segment of the eye.

Generation of anti-tumour immune response using dendritic cells pulsed with carbonic anhydrase IX-Acinetobacter baumannii outer membrane protein A fusion proteins against renal cell carcinoma

Carbonic anhydrase IX (CA9), a specific molecular marker for renal cell carcinoma (RCC), serves as a potential target for RCC‐specific immunotherapy using dendritic cells (DCs). However, pulsing of DCs with CA9 alone is not sufficient for generation of a therapeutic anti‐tumour immune response against RCC. In this study, in order to generate a potent anti‐tumour immune response against RCC, we produced recombinant CA9‐Acinetobacter baumannii outer membrane protein A (AbOmpA) fusion proteins, designated CA9‐AbOmpA, and investigated the ability of DCs pulsed with CA9‐AbOmpA fusion proteins in a murine renal cell carcinoma (RENCA) model. A recombinant CA9‐AbOmpA fusion protein was composed of a unique proteoglycan‐related region of CA9 (1–120 amino acids) fused at the C‐terminus with transmembrane domain of AbOmpA (1–200 amino acids). This fusion protein was capable of inducing DC maturation and interleukin (IL)‐12 production in DCs. Interaction of DCs pulsed with CA9‐AbOmpA fusion proteins with naive T cells stimulated secretion of IL‐2, interferon (IFN)‐γ and tumour necrosis factor (TNF)‐α in T cells. Lymphocytes harvested from mice immunized with DCs pulsed with CA9‐AbOmpA fusion proteins secreted IFN‐γ and showed a specific cytotoxic activity against CA9‐expressing RENCA (RENCA‐CA9) cells. Administration of CA9‐AbOmpA‐pulsed DC vaccine suppressed growth of RENCA‐CA9 cells in mice with an established tumour burden. These results suggest that DCs pulsed with CA9‐AbOmpA fusion proteins generate a specific anti‐tumour immune response against RCC, which can be utilized in immunotherapy of RCC.