• Macromolecular Research
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• v.11 no.4
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• pp.207-223
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• 2003

For last five years, we are developing the novel local drug delivery devices using biodegradable polymers, especially polylactide (PLA) and poly(D,L-lactide-co-glycolide) (PLGA) due to its relatively good biocompatibility, easily controlled biodegradability, good processability and only FDA approved synthetic degradable polymers. The relationship between various kinds of drug [water soluble small molecule drugs: gentamicin sulfate (GS), fentanyl citrate (FC), BCNU, azidothymidine (AZT), pamidronate (ADP), $1,25(OH)_2$ vitamin $D_3$, water insoluble small molecule drugs: fentanyl, ipriflavone (IP) and nifedipine, and water soluble large peptide molecule drug: nerve growth factor (NGF), and Japanese encephalitis virus (JEV)], different types of geometrical devices [microspheres (MSs), microcapsule, nanoparticle, wafers, pellet, beads, multiple-layered beads, implants, fiber, scaffolds, and films], and pharmacological activity are proposed and discussed for the application of pharmaceutics and tissue engineering. Also, local drug delivery devices proposed in this work are introduced in view of preparation method, drug release behavior, biocompatibility, pharmacological effect, and animal studies. In conclusion, we can control the drug release profiles varying with the preparation, formulation and geometrical parameters. Moreover, any types of drug were successfully applicable to achieve linear sustained release from short period ($1{\sim}3$ days) to long period (over 2 months). It is very important to design a suitable formulation for the wanting period of bioactive molecules loaded in biodegradable polymers for the local delivery of drug. The drug release is affected by many factors such as hydrophilicity of drug, electric charge of drug, drug loading amount, polymer molecular weight, the monomer composition, the size of implants, the applied fabrication techniques, and so on. It is well known that the commercialization of new drug needs a lot of cost of money (average: over 10 million US dollar per one drug) and time (average: above 9 years) whereas the development of DDS and high effective generic drug might be need relatively low investment with a short time period. Also, one core technology of DDS can be applicable to many drugs for the market needs. From these reasons, the DDS research on potent generic drugs might be suitable for less risk and high return.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.32 no.4
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• pp.295-307
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• 2006

Styela clava, called non-native tunicate or sea squirt, is habitat which include bays and harbors in Korea and several sites in the sea faced world. We fabricate cellulose membrane nerve conduit (CMNC) from this native sea squirt skin, and evaluate the capacity of promoting peripheral nerve regeneration in the rat sciatic nerve defect model. After processing the pure cellulose membrane from the sea squirt skin as we already published before, CMNC was designed as a non-tubular sheet with 14 mm length and 4 mm width. Total eleven male Spraque-Dawley rats (12 weeks, weighing 250 to 300g) were divided into sham group (n=2), silicone tube grafted control group (n=3) and experimental group (n=6). Each CMNC grafted nerve was evaluated after 4, 8 and 12 weeks in the experimental group, and after 12 weeks, sciatic function was evaluated with sciatic function index (SFI) and gait analysis, and histomorphology of nerve conduit and the innervated tissues of sciatic nerve were all examined using image analyzer and electromicroscopic methods in the all groups. The regenerated axon and nerve sheath were found only in the inner surface of the CMNC after 4 weeks and became more thicker after 8 and 12 weeks. In the TEM study, CMNC grafted group showed more abundant organized myelinated nerve fibers with thickened extracellular matrix than silicone conduit grafted group after 12 weeks. The sciatic function index (SFI) and ankle stance angle (ASA) in the functional evaluation were $-47.2{\pm}3.9$, $35.5^{\circ}{\pm}4.9^{\circ}$ in CMNC grafted group (n=2) and $-80.4{\pm}7.4$, $29.2^{\circ}{\pm}5.3^{\circ}$ in silicone conduit grafted group (n=3), respectively. And the myelinated axon was 41.59% in CMNC group and 9.51% in silicone conduit group to the sham group. The development of a bioactive CMNC to replace autogenous nerve grafts offers a potential and available approach to improved peripheral nerve regeneration. As we already published before, small peptide fragment derived from the basement membrane matrix proteins of squirt skin, which is a kind of anchoring protein composed of glycocalyx, induced the effective axonal regeneration with rapid growth of Schwann cells beneath the inner surface of CMNC. So the possibilities of clinical application as a peripheral nerve regeneration will be able to be suggested.

• Journal of Periodontal and Implant Science
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• v.37 no.4
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• pp.719-732
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• 2007

Purpose: Various bone graft materials are being used for periodontal tissue regeneration. Th materials are being developed continuously for ideal clinical effects. Therefore, it is necessary to identify the clinical characteristics of each bone graft material through comparing the various bone graft materials statistically and in doing so, proposing a more efficient bone graft material. In this study, the following results were attained through comparing the clinical effects among the bone graft materials, using the statistical method based on the clinical studies published at the department of periodontology of Yonsei hospital. Materials and Method: 6 selected studies of department of Periodontology at Yonsei University Hospital were based on clinical study of bone grafting in intrabony defects. It was compared the clinical parameters among the 6 clinical studies, using the statistical META analysis. Result: When comparing the probing depth reduction, there was a relatively great amount of decease when using the xenograft, Anorganic Bovine Derived Hydroxapatite Bone Matrix/Cell Binding Peptide(ABM/P-15: PepGen $P-15^{(R)}$) and the autogenous bone and absorbable membrane, d, 1-alctide/glycolide copolymer(GC: $Biomesh^{(R)}$). The allogfrafts showed a relatively low decrease in the probing depth and clinical attachment change. It also showed a slight decrease in the bone probing depth. The allografts showed various results according to different bone graft materials. When comparing the ABM/P-15 and bovine bone $powder(BBP^{(R)})$, ABM/P-15 showed a relatively high clinical attachment level and the bovine bone powder showed a relatively high clinical attachment level. The probing depth change and gingival recession change showed a lower value than the mean value between the two bone graft materials. The synthetic bone showed a relatively high decrease in clinical attachment level and periodontal probing depth change. There was a relatively larger amount of gingival recession when using Bioactive Glass(BG) but a relatively low bone regeneration effect was seen. Conclusion: Good restorative results of the periodontal tissue can be attained by applying the various bone graft materials being used today after identifying the accurate clinical effects.

• Korean Journal of Poultry Science
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• v.45 no.4
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• pp.261-272
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• 2018

This study was conducted to evaluate the difference in the quality of chicken thigh meat from conventional and animal welfare farms during refrigeration storage over 9 days. Chicken thigh meat from conventional (CTC, n = 30) and animal welfare farms (CTW, n = 30) was tested. The pH value was significantly lower in CTW (6.28) than in CTC (6.37) on day 1; however, no significant differences were found on subsequent days. The yellowness of CTW was higher than that of CTC on day 1, but CTW showed lower yellowness than did CTC on day 7 and 9. The cooking loss, water holding capacity, lightness, redness, and coliform levels of CTC did not show any significant difference when compared with CTW during storage. The shear force of CTW was significantly higher than that of CTC on day 1, 3, 7, and 9. Total microorganism and coliform in CTC and CTW increased with increasing storage days. On day 7 and 9, the total microorganism level of CTW was lower than that of CTC. The thiobarbituric acid value of CTW was lower than that of CTC on day 9. The volatile basic nitrogen (VBN) of CTW was lower than that of CTC during storage. Anserine content and 1,1-diphenyl-2-picryl-hydrazyl(DPPH) scavenging activity of CTW was significantly higher than CTC on day 1. These results suggest that CTW stayed fresher for longer than did CTC because of low total microorganism level on day 7 and 9, and VBN during refrigerated storage.