• Journal of Nutrition and Health
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• v.26 no.7
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• pp.858-866
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• 1993

S.D.rats were fed with 3.4% tyrosine supplemented diet for 5 days. Tyrosine diet had no effects on brain NE and MHPG-SO4 levels in non-stressed rats. When these animals were given 3 hr-immobilization stress, they responded in a manner that coped better to the stress. This was measured by the increase in brain MHPG-SO4 indicating the increase in norepinephrine turnover by the stressed animals. When rats were stressed, fed basal or high-tyrosine diet, brain tyrosine concentration dropped more than 26% over the non-stress control animals. 3-hr immobilization stress also decreased brain NE levels. However, while the stress resulted in a significant decrease(p<0.05) of brain NE in basal diet, the decrease was not significant in high-TYR diet group. And as the stress index, serum corticosterone, glucose, and free fatty acid concentratons also were assayed. In this study, it was found that high-TYR diet prevented the stress-induced depletion of brain NE and suppressed the rise in serum corticosterone, glucose, and free fatty acid. These results suggest that high-TYR diet increases the coping ability of body to stress.

• Korean Journal of Medicinal Crop Science
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• v.17 no.5
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• pp.328-334
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• 2009

Experimental purpose was to evaluate growth characteristic and abscisic acid (ABA) responses against salt/drought stresses. In the shoot biomass, creeping thyme was tolerated in mild NaCl stress, ranging 0 to 100 mM, while it was severely reduced in higher salinity. Under constant drought stress, the shoot biomass of creeping thyme showed a worse value compared to that of 100 mM NaCl treatment. Chlorophyll degradation was more severe in immature leaf than mature leaf under salt and drought stresses. In salt stress, immature leaf produced much amounts of ABA compared to mature leaf and also immature leaf showed faster increase of ABA than that of mature leaf. In drought stress, immature leaf responded to stress within 24 hours by the increase of ABA, while mature leaf responded to at 72 hours. Our results recommended that the optimal salinity level of creeping thyme was 50~100 mM NaCl.

• Journal of Applied Biological Chemistry
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• v.42 no.2
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• pp.66-70
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• 1999

Effects of the enhanced level of L-ascorbic acid (AA) on the water deficit-induced oxidative damage were studied in rice (Oryza sativa L.) seedlings. The seedlings sprayed with 20 to 80 mM L-galactono-${\gamma}$-lactone (GL), a putative precursor of AA, showed 2 to 5-fold higher levels of AA compared with controls. Pretreatment of the seedlings with GL prior to water stress imposition caused virtually no effect on dehydration of tissues during water deficit but substantially mitigated oxidative injury, as accessed by 2-thiobarbituric acid-reactive substances, ${\alpha}$-tocopherol, chlorophylls and ${\beta}$-carotene. Proline accumulation during water stress was also significantly lowered in the treated seedlings. In a complementary experiment, AA retarded photodegradation of ${\alpha}$-tocopherol in isolated thylakoids far more efficiently than glutathione. GL in itself did not show any noticeable reactivity toward ${\alpha}$-tocopheroxyl radical. The results demonstrate the antioxidative function of AA in rice seedlings encountering water-limited environments, suggesting a critical role of AA as a defense against oxidative stress in plants.

• The Journal of Korean Medicine
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• v.17 no.1 s.31
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• pp.146-170
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• 1996

This study aimed to evaluate the anti-stress effects of Walgukhwan, Walgukhwan+Ejintang and Wal gukhwan+Samultang. The experimental animals treated with each extracts during 15 days before the immobilization stress. And each experimental animals were endowed with 12 hours immobilization stress. Then the brain, blood and urine catecholamine contents and serum total cholesterol, triglyceride and free fatty acid levels were studied. The result were as followed; 1. Walgukhwan, Walgukhwan+Ejintang and Walgukhwan+Samultang were not statistically effective to the changes of the body weight. 2. Walgukhwan was statistically effective to the increase of the blood norepinephrine content as compared with control. 3. Walgukhwan+Ejintang was statistically effective to the increase of the blood and urine norepinephrine contents as compared with control. 4. Walgukhwan+Samultang was statisticallv effective to the increase of the brain, blood and urine norepinephrine contents and also to the increase of the blood and urine dopamine contents as compared with control. 5. Walgukhwan was statistically effective to the increase of the serum free fatty acid level as compared with control. 6. Walgukhwan+Ejintang was statistically effective to the increase of the serum triglyceride and free fatty acid levels as compared with control. 7. Walgukhwan+Samultang was statistically effective to the increase of the serum total cholesterol, triglyceride and free fatty acid levels as compared with control.

• Journal of dental hygiene science
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• v.19 no.3
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• pp.198-204
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• 2019

Background: Oxidative stress is a known to be associated with in the pathogenesis of many inflammatory diseases, including periodontitis. Ursolic acid is a pentacyclic triterpenoid with has antimicrobial, antioxidative, and anticancer properties. However, the role of ursolic acid in the regulating of osteogenesis remains undetermined. This study was aimed to elucidate the crucial osteogenic effects of ursolic acid and its ability to inhibit oxidative stress by targeting the immediate early response 3 (IER3)/nuclear factor erythroid 2-related factor 2 (Nrf2) pathway. Methods: Cell proliferation was determined using water-soluble tetrazolium salt assay, cell differentiation was evaluated by alkaline phosphatase (ALP) activity, and formation of calcium nodules was detected using alizarin red S stain. Generation of reactive oxygen species (ROS) was determined using by DCFH-DA fluorescence dye in hydrogen peroxide ($H_2O_2$)-treated MG-63 cells. Expression levels of IER3, Nrf2, and heme oxygenase-1 (HO-1) were analyzed using western blot analysis. Results: Our results showed that ursolic acid up-regulated the proliferation of osteoblasts without any cytotoxic effects, and promoted ALP activity and mineralization. $H_2O_2$-induced ROS generation was found to be significantly inhibited on treatment with ursolic acid. Furthermore, in $H_2O_2$-treated cells, the expression of the early response genes: IER3, Nrf2, and Nrf2-related phase II enzyme (HO-1) was enhanced in the presence of ursolic acid. Conclusion: The key findings of the present study elucidate the protective effects of ursolic acid against oxidative stress conditions in osteoblasts via the IER3/Nrf2 pathway. Thus, ursolic acid may be developed as a preventative and therapeutic agent for mineral homeostasis and inflammatory diseases caused due to oxidative injury.

• Journal of the Korean Society of Clothing and Textiles
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• v.30 no.4 s.152
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• pp.607-614
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• 2006

This study was carried out to suggest the optimal spinning process condition which provides a proper range of tenacity and biodegradability as textile fibers. The effects of the melt spinning speed and heat treatment on the mechanical property and biodegradability of polylactic acid fiber were investigated. Polylactic acid(PLA) was spun in a high spinning speed of $2000{\sim}4000m/min$. Each specimen was heat-treated at $100^{\circ}C$ during 30min. Mechanical properties such as breaking stress and the degree of crystallinity were evaluated using WAXS. Biodegradability was estimated from the decrease of breaking stress, weight loss, and the degree of crystallinity after soil burial. Experimental results revealed that heat treated specimens showed higher breaking stress than untreated specimens, but the increase was not so high as was expected from the remarkable change of crystallinity by heat treatment. It was concluded that breaking stress was more influenced by spinning speed than heat treatment. In the soil burial test, however biodegradability calculated from weight loss was more influenced by heat treatment than spinning speed.

• The korean journal of orthodontics
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• v.24 no.1 s.44
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• pp.105-114
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• 1994

The movement of teeth during orthodontic treatment requires bone remodeling process of bone formation and bone resolution. To find out the changes occuring in the cell itself, mechanical stress was applied to the cell populations involved in the bone metabolism. Bone tissue cell populations were isolated from fetal rat calvaria and divided into OC and OB groups. Following results were obtained from measuring the changes in acid & alkaline phosphatease activity, cyclic AMP and $PGE_2$ production in time lapse after the application of mechanical stress. 1. In case of the marker enzyme of specific bone tissue cell, acid phosphatase activity was high in OC group and alkaline phosphatase activity was high in OB group. 2. After the mechanical stress was applied, acid phosphatase activity was decreased in both OC and OB groups and alkaline phosphatase activity was increase in OB group. 3. When the mechanical stress was applied for 15, 30 and 60 minutes, the production of $PGE_2$ increased in both OC and OB groups, as the time span increased. 4. When the mechanical stress was applied for 20 and 40 minutes, the production of $PGE_2$ increased in both OC and OB groups, as the time span increased.

• Journal of Microbiology and Biotechnology
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• v.28 no.1
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• pp.109-114
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• 2018

Coxsackievirus Type B3 (CVB3) is an enterovirus that belongs to the Picornaviridae and causes various diseases such as myocarditis and hand-foot-mouth disease. However, an effective antiviral drug is still not developed. In this study, we looked for potential inhibitors of CVB3 replication by examining the survival of CVB3-infected HeLa cells. We detected an antiviral effect by cholic acid and identified it as a candidate inhibitor of CVB3 replication. Cholic acid circulates in the liver and intestines, and it helps the digestion and absorption of lipids in the small intestine. HeLa cells were cultured in 12-well plates and treated with cholic acid (1 and $10{\mu}g/ml$) and $10^6PFU/ml$ of CVB3. After 16 h post-infection, the cells were lysed and subjected to western blot analysis and RT-PCR. The production of the viral capsid protein VP1 was dramatically decreased, and translation initiation factor eIF4G1 cleavage was significantly inhibited by treatment with $10{\mu}g/ml$ cholic acid. Moreover, cholic acid inhibited ERK signaling in CVB3-infected HeLa cells. RT-PCR showed that the amounts of the CVB3 RNA genome and mRNA for the ER stress-related transcription factor ATF4 were significantly reduced. These results showed that cholic acid strongly reduced ER stress and CVB3 proliferation. This compound can be developed as a safe natural therapeutic agent for enterovirus infections.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.28 no.1
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• pp.42-57
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• 2002

본 연구는 널리 알려져 있는 항산화제들의 세포 수준에서의 anti-oxidative stress 효과 및 그 기작을 알아보기 위한 연구이다. 연구에 사용한 항산화제로는 지용성인 retinol, $\alpha$-tocopherol, propyl gallate(PG) 및 butylated hydroxy toluene(BHT)과 수용성인 ascorbic acid, $\alpha$-glucosyl rutin 및 green tea extract를 사용하였으며 이들 항산화제들의 시간별 세포 생존율을 NR assay 로 측정한 후 적정 농도에서 DCFH-DA(2', 7'-dichlorofluorescin-diacetate) 를 이용하여 항산화제들의 anti-oxidative stress 억제 효과를 시간별로 측정하였다. 또한 이들 항산화제의 항산화 기작을 알아보기 위하여 NBT(Nitro-blue-tetrazolium) 및 DPPH(Diphenyl-picry-hydrazl)도 병행하여 실시하였다. Anti-oxidative stress 실험에서 지용성 항산화제들은 전반적으로 수용성 항산화제에 비하여 세포에 대한 독성이 상대적으로 강하여 retinol 의 경우에는 0.01%에서 oxidative stress 억제 효과를 관할할 수 있었으며 1 시간경과 후 측정시 53.1%의 억제 효과를 보여 주었다. PG 의 경우에는 0.1%에서 2 시간 경과 후 측정시 50%의 oxidative stress 억제 효과를 보여주었다. 수용성 항산화제인 green tea extract 및 $\alpha$-glucosyl rutin의 경우에는 1%에서 1시간 경과 후 측정시 각 각 51.6% 및 69.7%의 oxidative stress 억제 효과를 관찰할 수 있었다. 또한 시료처리 후 자외선 조사시 oxidative stress 억제 효과의 경우 수용성 항산화제인 ascorbic acid, $\alpha$-glucosyl rutin 및 green tea extract 와 지용성 항산화제 중에서는 $\delta$-tocopherol 에서만 oxidative stress 억제 효과가 관찰되었으나 자외선을 조사 하지 않았을 때 보다 약 20%-40%까지 억제 효과가 감소되었다. 그리고 PG 및 retinol 의 경우에는 자외선 조사시 독성이 증가하여 oxidative stress 억제 효과를 측정할 수 없었다. NBT실험에서 $\alpha$-glucosyl rutin, $\alpha$-tocopherol 및 PG 1%에서 70%이상의 superoxide anion 생성 억제 효과를 보였으며 DPPH 실험에서는 ascorbic acid 와 PG 1%에서 98%의 hydroxyl radical 생성 억제 효과를 보여 주었다. 본 실험을 통하여 BHT 를 제외하고 전반적으로 세포 수준에서의 oxidative stress 에 대한 억제 효과를 확인해 볼 수 있었으며 특히 수용성 항산화제들에서 두드러진 효과를 보여 주었다.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.5
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• pp.181-187
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• 2000

Fatigue tests under acid fog environment were carried out to investigate the effect of acid fog on the corrosion fatigue strength of SM55C in comparison with distilled water. Main results obtained are as follows. The fatigue strength of SM55C under acid fog environment are remarkably decreased as compared with that of distilled water specimen. The corrosive effect of acid fog on fatigue strength are more serious under low stress amplitude level than under high stress amplitude level, and this leads to continuous reduction of fatigue strength. Under acid fog environment in early stage of crack growth. because the corrosive components dissolve the crack face offensively. the unstable fracture surface appears. But, the stable corrosion precipitation and products layer are formed on the fracture surface in accordance with the time pass.