• Bulletin of the Korean Chemical Society
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• v.27 no.9
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• pp.1335-1340
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• 2006

It has been found that a number of diseases are associated with mutations in the mitochondrial DNA. Therapeutic gene delivery to mitochondria has been suggested as a clinical option for these diseases. In this study, we developed a gene carrier to mitochondria by the conjugation of mitochondrial leader peptide (LP) to polyethylenimine (PEI). Mitochondrial LP conjugated PEI (PEI-LP) was synthesized with low molecular weight PEI (2,000 Da, PEI2K). Gel retardation assay showed that PEI2K-LP formed complexes at a 1.0/1 weight ratio. In addition, PEI2K-LP protected DNA from the enzymatic degradation for at least 60 min, while naked DNA was completely degraded within 20 min. PEI2K-LP was compared with LP conjugated high molecular weight PEI (25,000 Da, PEI25K) in terms of toxicity and delivery efficiency. MTT assay showed that PEI2K-LP had much lower cytotoxicity than PEI25K-LP to 293 cells. In addition, cell-free DNA delivery assay showed that PEI2K-LP delivered more DNA to mitochondria at a 1.8/1 weight ratio than naked DNA or PEI. This result suggests that PEI2K-LP may be useful for the development of mitochondrial gene therapy system with lower cytotoxicity.

• The Korean Journal of Food And Nutrition
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• v.19 no.4
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• pp.358-365
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• 2006

To study simultaneous water and solute transport kinetics during soaking in concentrated solution, the influence of the concentration and molecular weight of the solute(polyethylene glycol(PEG) and NaCl) in the soaking solution and the temperature on the water loss and solute gain rates were observed by using a model vegetable tissue(potato). When potato slices$(4cm{\times}4cm{\times}0.1cm)$ soaked in 60% PEG solutions, the water loss rate of the early phase decreased with increasing of the molecular weight of PEG from 200 to 6,000, while the final water loss increased with increasing the molecular weight of PEG and it reached to 80%. The cell wall of potato tissue was permeable to NaCl and PEGs of which average molecular weight is smaller than 400 but it was not permeable to PEG 600 and larger molecules. PEG which has average molecular weight below 600 induced plasmolysis and those above 600 induced cytorrhysis. The water loss rate of potato sample soaked in smaller molecular weight PEG solution was faster than those soaked in higher molecular weight PEG solution before cytorrhysis happened. The water loss rate was reversed after cytorrhysis happened. The volume change of potato within the first 60 minutes was larger in low molecular PEG solution but the final ratio of decreasing volume was larger in high molecular PEG solutions. In PEG 200 solution, the potato tissue was slightly shrinked without shape change. However, in PEG 4,000 solution, volume of potato was reduced significantly and potato tissue was twisted.

• Journal of Environmental Health Sciences
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• v.24 no.3
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• pp.48-53
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• 1998

Chitin is known as biodegradable natural polymer. But, in spite of various application of chitin from waste marine sources, commercial use of chitin has been limited due to highly resistance to chemicals and the absense of proper solvents. We made various viscosity of chitosan from chitin by change of Mima's method through the deacetylation which is various condition of NaOH concentration, reaction time and temperature. Also, Polyvinyl alcohol/chitosan blend films were prepared by different solution blends containing the ratio of 5, 10, 15 and 20% chitosan and low, medium, high molecular weight of chitosan to find a more useful biodegradable polymer. Thermal and mechanical properties of PVA/chitosan blend films such as DSC, impact strength, tensile strength and morphological changes by SEM were determined. The 10-15% PVA/chitosan(low, medium) blend films were similar to PVA. Also, PVA/chitosan blend films at the laboratory soil test(Pot Test) were completely degraded in month with four kinds of soils by microorganisms.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.36 no.4
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• pp.321-326
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• 2003

Antioxidative activities of low molecular weight biocompounds purified from anchovy (Engraulis japonicus) sauce fermented at $15\pm3^{\circ}C$ for 5 years were investigated. The fermented anchovy sauce showed 5 peaks on gel chromatography pattern. Antioxidant activity of peak 2 was $82.7\%$ followed by $42.6\%$ of peak 1. Main antioxidant compounds of peak 1 were glutamic acid and lysine, but those of peak 2 were not confirmed by amino acid sequence analysis.

• Korean Journal of Human Ecology
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• v.5 no.1
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• pp.75-80
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• 1996

The immunogenecity of low molecular weight ($MW{\le}30,000$) immunogens in laying hens was investigated. Immunogens were insulin derivatives and ${\beta}$-lactoglobulin(${\beta}-Lg$). Insulin derivatives were reduced- carboxymethylated(RCM) insulin, and RCM-A and RCM-B chain of insulin. The yolk antibodies against RCM-A chain of insulin appeared after the first immunization. The yolk antibodies against RCM-B chain of insulin were elicited 5 weeks after the third booster injection. Although the anti-RCM-B chain yolk antibodies recognized native insulin, the anti-RCM-A chain yolk antibodies didn't native insulin. The anti-RCM insulin yolk antibodies were induced after the second booster injection and showed cross-reactivities with native insulin. On the other hand, ${\beta}-Lg$ showed stronger immunogenecity than insulin derivatives. The $anti-{\beta}-Lg$ yolk antibodies were produced after the second booster injection and the peak titer was reached 3 weeks after the third booster injection.

• Nutritional Sciences
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• v.6 no.2
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• pp.94-99
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• 2003

The purpose of this study was to investigate in vivo lipid peroxidation in rats under conditions of streptozotocin-induced oxidative stress and the antioxidant effects of probucol. In vivo lipid peroxidation was observed by measuring low molecular weight aldehydes and related carbonyl compounds in rat urine. Three groups of male Wistar rats weighing 165-190 g were used: normal (N), streptozotocin-induced oxidative stress (OS) and oxidative stress plus probucol treatment (P). following streptozotocin treatment of the rats, a variety of secondary lipid peroxidation products were increased. The levels of butanal, hexanal, hex-2-enal, kept-2-enal, octanal, non-2-enal, deca-2,4-dienal, 4-hydroxyhex-2-enal, 4-hydroxyno n-2-enal, malondi aldehyde(MDA), and unknown carbonyl compounds were significantly increased in the oxidative stress group compared to the control group. Treatment with probucol resulted in significant decreases in buoal, hexanal, hex-2-enal, octanal, deca-2,4-dienal, 4-hydroxyhex-2-enal, MDA and unknown carbonyl compounds. Hept-2-enal, hepta-2,4-dienal and non-2-enal appeared to have a tendency to decrease due to pobucol treatment.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.482-483
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• 2003

We have synthesized a new material of polyoxetane based liquid crystalline polymer/liquid crystal (LCP/LC) for flexible memory or dynamic mode device and characterized the electro-optics behavior of this system. The microscopic dynamic behavior of main chain, side chain, and the low molecular weight LC were characterized by X-ray scattering and time resolved FTIR..

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.312-315
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• 2004

In this paper we investigated the behavior of low molecular weight silicone fluids in silicone rubber by W treatment with solvent-extraction and GPC. It was shown that LMW quantity which was extracted by solvent-extraction was decreased in UV treatment time. $200{\sim}450\;g/mol$ distribution of LMW silicone fluid was contributed to recovery. It was similar to result from corona discharge. Morphological analysis was investigated by scanning electron microscope(SEM) and X-ray diffraction (XRD). The behavior of LMW silicone fluids in silicone rubber which was contributed to recovery was discussed.

• Korean Journal Plant Pathology
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• v.13 no.1
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• pp.1-4
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• 1997

Viroid-like RNA molecules were detected from the low molecular weight RNAs isolated from the Korean peonies which showed typical viroid symptoms of epinasty and dwarfing. Low molecular weight RNAs including viroid RNA molecules were purified by the Qiagen anion exchange minicolumns. Viroid-like RNA molecules showed a single viroid specific band in the native polyacrylamide gel. They were separated into two bands in the denaturing gel conditions. The band of circular form of viroid-like RNAs was crossed over the horizontal band of the linear form of viroid-like RNA molecules in 0~8 M urea gradient gel under the denaturing conditions of 37$^{\circ}C$. The two circular forms of viroid-like RNA molecules were detected in the reverse polyacrylamide gel electrophoresis. The viroid-like RNA molecules purified from the peonies were supposed to be unidentified viroid RNA molecules.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.266-269
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• 2001

This paper investigated the aging characteristic under long-term corona discharge on roan temperature vulcanized silicone rubber, which has been using as a protective coating material for solving the contaminant problem. The applied electrical field is 10kV/cm ac and corona discharge treatment was applied on RTV silicone rubber sheet for maximum 250 hours. With the duration of corona discharge. the diffusible low molecular weight species increased, which was determined the usage of n-hexane extraction method. In addition, the contaminant layer was formed on the treated surface, and then measured the contact angle. We investigated the relation of contact angle and diffusible low molecular weight species. It is found that scissor of main chain PDMS and side chains $(CH_3)$ and the generation of LMW species were occurred by a corona discharge. The improvement of hydrophobicity rate is thought due to the increase of diffusible LMW species.