• YAKHAK HOEJI
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• v.39 no.3
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• pp.283-288
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• 1995

Rapid gas chromatographic profiling method was applied to saliva from healthy subjects for the analysis of free organic acids. Saliva samples were first saturated with NaHCO$_{3}$ and extracted with diethyl ether. The aqueous phase was solid-phase extracted using Chromosorb P as the adsorbent and diethyl ether as the eluent after the acidification and NaCl saturation, followed by triethylamine treatment. The resulting tiiethylammonium salts of acids were directly converted into stable tert.-butyl-dimethylsflyl derivatives, with subsequent analysis by dual-capiuary column gas chromatography and gas chromatograpy -mass spectrometry. From the ten saliva samples studied, twenty eight free organic acids including various fatty acids, hydroxy acids, dicarboxylic acids, md aromatic acids were tentatively identified. Among the acids identified , the concentration of lactic acid was highest for five saliva samples while $\alpha$-hydroxyisocaproic acid was most abundant for me sample, and succinic acid and glycolic acid for two samples. respectively. When the GC profiles were simplified to the corresponding acid retention index spectra of bar graphical form, they presented characteristic patterns for each individual.

• Journal of the Korean institute of surface engineering
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• v.36 no.4
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• pp.317-323
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• 2003

The effect of additives such as complexing agents, stabilzers and boric acid on the bath stability and the deposition rate of electroless black Ni-Zn plating has been examined. The deposits obtained became black and showed an amorphous structure. The significant increasing in the deposition rate was not found when only glycine and citric acid were used as complexing agents. The deposition rate increased up to 3 and 4 times by adding malic acid and glycolic acid as an additional complexing agent, respectively. The stabilizers and the boric acid, however, had little influence on the deposition rate.

• Applied Biological Chemistry
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• v.24 no.2
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• pp.120-125
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• 1981

Organic acids of Kochuzang (red pepper paste) prepared from glutinous rice, polished barley, wheat flour and sweet potato were analyzed by a gas chromatography. Lactic, pyruvic, succinic, fumaric, malic, pyroglutamic and citric acid were identified. And trace amount of oxalic acid was found in the Kochuzang prepared from sweet potato. The dominant organic acid of all samples was pyroglutamic acid, followed by pyruvic and citric acid. The organic acids were lower in Kochuzang from wheat flour than in other samples. The contents of succinic and fumaric acid were highest in Kochuzang prepared from sweet potato and were lowest in polished barley Kochuzang.

• Polymer(Korea)
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• v.34 no.2
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• pp.172-177
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• 2010

Although many researchers have studied the efficacy of paclitaxel (PTX) on many cells during the last two decades, little work has been reported on the importance of release kinetics inhibiting cell proliferation. The aim of this study is to examine the release behavior of the PTX on various biodegradable polymers such as poly(lactic-co-glycolic acid)(PLGA), poly-L-lactide (PLLA), and polycaprolactone (PCL) for drug-eluting stents (DES). The PTX from the fabricated films was released for 8 weeks and the degree of degradation of the films was observed by FE-SEM. Although the degradation time of PCL was the slowest, the PTX release rate was the fastest among them and followed by PLGA and PLLA with the equivalent PTX concentration. It suggests that hydrophobic drug such as PTX from polymer with low $T_g$ like PCL could be moved easily and released rapidly in body temperature.

• Journal of Pharmaceutical Investigation
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• v.40 no.4
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• pp.245-250
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• 2010

Porous poly(lactic-co-glycolic acid) microspheres (PLGA MS) have been utilized as an inhalation delivery system and a matrix scaffold system for tissue engineering. Here, gelatin (type A) is introduced as an extractable pH-responsive porogen, which is capable of controlling the porosity and pore size of PLGA microspheres. Porous PLGA microspheres were prepared by a water-in-oil-in-water ($w_1/o/w_2$) double emulsification/solvent evaporation method. The surface morphology of these microspheres was examined by varying pH (2.0~11.0) of water phases, using scanning electron microscopy (SEM). Also, their porosity and pore size were monitored by altering acidification time (1~5 h) using a phosphoric acid solution. Results showed that the pore-forming capability of gelatin was optimized at pH 5.0, and that the surface pore-formation was not significantly observed at pHs of < 4.0 or > 8.0. This was attributable to the balance between gel-formation by electrostatic repulsion and dissolution of gelatin. The appropriate time-selection between PLGA hardening and gelatin-washing out was considered as a second significant factor to control the porosity. Delaying the acidification time to ~5 h after emulsification was clearly effective to make pores in the microspheres. This finding suggests that the porosity and pore size of porous microspheres using gelatin can be significantly controlled depending on water phase pH and gelatin-removal time. The results obtained in this study would provide valuable pharmaceutical information to prepare porous PLGA MS, which is required to control the porosity.

• Polymer(Korea)
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• v.37 no.3
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• pp.323-331
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• 2013

Hesperidin (Hes) has known to having some functions like protection of blood circulatory system, anti-tumor effect, antioxidant effect and anti-inflammatory effect. The goal of this study is to demonstrate the relationship between Hes and inflammatory through in vitro and in vivo studies using poly(lactic-co-glycolic acid) (PLGA) film including Hes as a tissue engineered scaffold. To confirm the proliferation of cells on fabricated scaffold, cells (RAW 264.7 and NIH/3T3) were seeded on PLGA/Hes film then analyzed with MTT and SEM at 1 and 3 days after seeding. The results from ELISA, RT-PCR, and FACS for anti-oxident and anti-inflammatory effect showed that inflammatory response of PLGA/Hes film decreased more than that of PLGA film. Also, in vivo result confirmed that inflammatory response by implanted PLGA/Hes film decreased more comparing with PLGA film. This is because of anti-inflammatory effect of Hes reducing induced inflammatory cell and accumulation of fibrous capsule. The results showed that PLGA/Hes film's capacity on reducing inflammatory is better than PLGA film because of Hes.

• Archives of Plastic Surgery
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• v.34 no.3
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• pp.298-304
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• 2007

Purpose: This study was undertaken to investigate the osteogenic induction potential of PGA & FBS mixture on a calvarial defect in the rabbit. Methods: Twenty New zealand white rabbit, weighing from 3.5-4kg were allocated into each of the three groups. Four 8 mm sized bone defects were made on the parietal bone by drilling. In group I, the bony defects were implanted with $50{\mu}m$ thickness film containing mixture of PGA and FBS. In group II, with PGA only film, & in group III, the bony defects were left with no implants. Results were evaluated by using morphologic change, radiographic study, biochemical study and histologic examination at 1 week (group I n=7, group II n=7, group III n=14), 2 weeks (group I n=6, group II n=6, group III n=12) and 3 weeks (group I n=7, group II n=7, group III n=14) following implantation. Results: In the morphologic & radiographic study, the formation and corticalization of callus were observed earlier in group I than in groups II and III (p < 0.05). In histological examination, group I showed more abundant and faster new bone formation than in group II and III. In biochemical analysis, group I displayed more activity than in group II and III. Group I also showed more abundant osteopontin, osteocalcin than groups II and III. Conclusion: In conclusion, the results demonstrate that the mixture of PGA and FBS has an effect on osteoblastic formation in the rabbit model. It is considered that further evaluation of long term results on resorption, immunologic tissue reaction and response of applied mixture in the human model will be needed.

• Polymer(Korea)
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• v.37 no.5
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• pp.632-637
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• 2013

It has been widely accepted that costal cartilage cells (CCs) have more excellent initial proliferation capacity than articular cartilage cells as well as the easiness for isolation and collection. This study demonstrated that CCs might be one of the substitutes for articular cartilage cells by tissue engineered cartilage. Poly(lactic-co-glycolic acid) (PLGA) has been extensively tested and used as scaffold material but it was limited by the low attachment of cells and the induction of inflammatory cells. Base on previous our studies, we confirmed demineralized bone particle (DBP) had the power of the reduction of inflammatory reaction and the stimulation proliferation of cells. We fabricated PLGA scaffold loaded with 10, 20, 40 and 80 wt% DBP and then tested the possibility of the regeneration of cartilage using CCs. Assays of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and scanning electron microscope (SEM) carried out to evaluate the attachment and proliferation of CCs in DBP/PLGA scaffolds. Glycosaminoglycan (sGAG) and collagen contents assay were conducted to confirm the effects of DBP on formation of extracellular matrix. This study demonstrated that DBP/PLGA scaffolds showed significant positive effects on cell growth and proliferation due to the vitality of DBP as well as the possibility of the application of CCs for tissue engineered cartilage.

• Polymer(Korea)
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• v.38 no.2
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• pp.156-163
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• 2014

Hydroxyapatite has osteoconductivity, biocompatibility and noninflammatory, and it has been used clinically as artificial bone. In this study, we prepared hydroxyapatite/poly(lactic-co-glycolic acid) (PLGA) scaffolds using 0, 10, 20, 40 and 60 wt% of hydroxyapatite. We analyzed compressive strength, SEM analysis and FTIR for mechanical property of 3D hydroxyapatite/PLGA scaffolds. For biocompatibility tests, cell proliferation and viability were measured via MTT assay and SEM. We analyzed RT-PCR, FACS, histology (H&E, ED-1) for anti-inflammatory effect. This study showed that hydroxyapatite hybrid scaffolds have low inflammatory reaction compared with the PLGA. This result has a potential for the application of artificial bone graft material.

• Journal of Life Science
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• v.31 no.9
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• pp.849-855
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• 2021

Recently, as nanotechnology has been introduced and used in various fields, the development of new drugs has been accelerating. Nanoparticles have maintained blood drug concentration for extended periods of time with a single administration of the drug. The drug can then be selectively released only at the pathological site, thereby reducing side effects to other non-pathological sites. In addition, nanoparticles can be modified for selective target sites delivery for other specific diseases, with polymers being widely used in the manufacture of these nanoparticles. Poly (D,L-lactic-co-glycolic acid ) (PLGA) is one of the most extensively developed biodegradable polymers. PLGA is widely used in drug delivery for a variety of applications. It has also been approved by the FDA as a drug delivery system and is widely applied in controlled release formulations, such as in gene therapy treatments. PLGA nanoparticles have been developed as delivery systems with high efficiency to specific cell types by using passive and active targeting methods. After the development of a drug delivery system using PLGA nanoparticles, the drug is selectively delivered to the target site, and the effective blood concentration for extended periods of time is optimized according to the disease. In this review paper, we focus on ways to improve cell-specific treatment outcomes by examining the development of astrocyte selective nanoparticles based on PLGA nanomaterials for gene therapy.