• 한국세라믹학회지
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• 제35권10호
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• pp.1061-1069
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• 1998

The thermal instability of Al2TiO5 Ceramics was contrlled by solid solution with MgO SiO2 and ZrO2 through electrofusion in an arc furnace. The thermal expansion properties of Al2TiO5 composites show the hysteresis due to the strong anisotropy of The crystal axes of these material. These phenomena are ex-plained by the opening and closing of microcracks. The difference in microcracking temperatures e.g 587.6(ATG2), 405.9(ATG3) and 519.7$^{\circ}C$(ATG4) is caused by the difference in grain size and stabilizer type. The thermal shock behaviour under cyclic conditions between 750-1400-75$0^{\circ}C$ show no change in mi-crostructure and phase assemblage for all three stabilized specimens. After the thermal loading test at 110$0^{\circ}C$ for 100hrs. ATG1 and ATG2 materials decomposes completely to its components corundum and ru-tile in both cases. However with approximatelly 20% retention of the Al2TiO5 Thus in order to prevent decomposition of the stabilized material in the critical temperature range 800-130$0^{\circ}C$ it must be traversed within a short period of time.

• 분석과학
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• 제31권5호
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• pp.208-218
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• 2018

자가소화작용은 세포 내 물질들을 이중막 구조의 자가포식체를 형성하여 라이소좀(lysosome)과 융합한 후 이들을 분해시키는 과정이다. 자가소화작용은 유전적, 세포적, 생화학 수준에서 연구가 진행되어왔지만, 자가포식체의 미세구조 분석 및 정량적 분석은 체계적으로 이루어지지 않았다. 본 연구에서는 먼저, 기초 자가소화작용이 진행되는 환경과 기아상태로 자가소화작용을 유도한 환경의 세포에서 각각 자가포식체 막 형성에 중요한 역할을 하는 ATG5가 결핍된 섬유아세포와 정상 섬유아세포에서의 자가포식체의 미세구조를 비교 관찰 하였다. 정상 섬유아세포에서는 초기 패고포어, 초기 및 후기 자가포식체, 오토라이소좀과 같은 자가포식체의 단계별 미세구조를 확인한 반면, ATG5가 제거된 섬유아세포에서는 이중막 구조가 완성되지 않은 자가포식체 구조가 증가한 것을 확인하여 ATG5가 자가포식체 성숙에 중요한 역할을 함을 다시 한번 검증할 수 있었다. 본 연구를 통해 구축한 자가포식체 미세구조 분석법을 활용하여 확장된 폴리글루타민을 가지는 N-말단 헌팅틴 유전자를 발현시키는 헌팅턴병의 세포학적 모델에서 단계별 자가포식체를 분석하였다. 그 결과, 흥미롭게도 헌팅틴 단백질이 발현된 세포에서 후기 자가포식체가 증가하는 것을 확인할 수 있었으며, 이를 통해 헌팅틴 돌연변이 단백질 응집체 제거에 필요한 자가소화작용 활성화를 위해서 자가포식체와 라이소좀의 결합 단계를 촉진하는 것이 효과적일 가능성에 대해서 유추할 수 있었다. 결론적으로 전자현미경을 활용한 자가포식체의 단계별 미세구조 관찰 및 정량 분석이 다양한 인간 질병모델에 적용되고, 자가소화작용과 연관된 병리 메커니즘 연구에 기여할 수 있을 것으로 생각된다.

• 생명과학회지
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• 제19권5호
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• pp.625-632
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• 2009

결과적으로 본 연구에서 서로 다른 두 집단(RTG, ATG)의 비교시 저항성 트레이닝 집단(RTG)보다 유산소 트레이닝 집단(ATG)에서 산화질소(NO) 농도가 더 높게 나타났으며, 이는 지속적인 유산소 형태의 트레이닝이 간헐적인 저항성 형태의 트레이닝 보다 더 많은 산화질소(NO)가 생성 된다는 것을 알 수 있었다. 또한 심박수(HR)와 혈압(BP), 평균동맵압(MAP)의 감소에도 저항성 트레이닝(RT)보다는 유산소 트레이닝(AT)이 효과적이라는 것을 알 수 있었다. 그러나 유산소 트레이닝(AT)에 비해 저항성 트레이닝(RT)에서 유의하진 않았지만 산화질소(NO) 농도가 증가된 것은 주목할 만한 결과이다. 이러한 결과로 볼 때, 단기간일 지라도 혈관이완 및 자율신경계 도움을 줄 수 있는 것은 유산소 트레이닝(AT) 임을 알 수 있었고 이는 일반적으로 운동을 선택할 시(근력과 근비대를 제외한 운동) 도움을 줄 수 있다고 사료된다. 또한 추후 연구에서는 12주 이상의 장기간의 트레이닝을 통해 저항성 트레이닝(RT)이 혈관이완의 직접적인 척도인 산화질소(NO) 농도에 관한 연구가 필요시 된다.

• Journal of Microbiology and Biotechnology
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• 제31권6호
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• pp.833-839
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• 2021

Bacillus subtilis CH3-5 isolated from cheonggukjang secretes a 28 kDa protease with a strong fibrinolytic activity. Its gene, aprE3-5, was cloned and expressed in a heterologous host (Jeong et al., 2007). In this study, the promoter of aprE3-5 was replaced with other stronger promoters (P_cry3A, P₁₀, P_SG1, P_srfA) of Bacillus spp. using PCR. The constructed chimeric genes were cloned into pHY300PLK vector, and then introduced into B. subtilis WB600. The P10 promoter conferred the highest fibrinolytic activity, i.e., 1.7-fold higher than that conferred by the original promoter. Overproduction of the 28 kDa protease was confirmed using SDS-PAGE and fibrin zymography. RT-qPCR analysis showed that aprE3-5 expression was 2.0-fold higher with the P10 promoter than with the original promoter. Change of the initiation codon from GTG to ATG further increased the fibrinolytic activity. The highest aprE3-5 expression was observed when two copies of the P₁₀ promoter were placed in tandem upstream of the ATG initiation codon. The construct with P10 promoter and ATG and the construct with two copies of P10 promoter in tandem and ATG exhibited 117% and 148% higher fibrinolytic activity, respectively, than that exhibited by the construct containing P10 promoter and GTG. These results confirmed that significant overproduction of a fibrinolytic enzyme can be achieved by suitable promoter modification, and this approach may have applications in the industrial production of AprE3-5 and related fibrinolytic enzymes.

• BMB Reports
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• 제53권5호
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• pp.254-259
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• 2020

Increasing evidence suggests the role of miR-449a in the regulation of tumorigenesis and autophagy. Autophagy plays an important role in the malignancy of T-cell lymphoma. However, it is still unknown whether miR-449a is associated with autophagy to regulate the malignancy of T-cell lymp homa. In this study, we for the first time demonstrated that miR-449a enhanced apoptosis of T-cell lymphoma cells by decreasing the degree of autophagy. Further, miR-449a downregulated autophagy-associated 4B (ATG4B) expression, which subsequently reduced the autophagy of T-cell lymphoma cells. Mechanistically, miR-449a decreased ATG4B protein level by binding to its mRNA 3'UTR, thus reducing the mRNA stability. In addition, studies with nude mice showed that miR-449a significantly inhibited lymphoma characteristics in vivo. In conclusion, our results demonstrated that the "miR-449a/ATG4B/autophagy" pathway played a vital role in the malignancy of T-cell lymphoma, suggesting a novel therapeutic target.

• Clinical and Experimental Pediatrics
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• 제58권7호
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• pp.267-269
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• 2015

Antithymocyte globulin (ATG) is used as an immunosuppressive treatment (IST) to deplete clonal suppressor T cells in patients with severe aplastic anemia (SAA). The depletion of suppressor T cells by ATG may affect the activation of B cells, which results in an increased risk for autoimmune conditions. A 12-year-old boy was diagnosed with idiopathic SAA. As he did not have an human leukocyte antigen-matched sibling, he was treated with rabbit ATG (3.5 mg/kg/day for 5 days) and cyclosporine. Five months later, he became transfusion independent. However, 23 months after IST, he complained of mild hand tremors, sweating, weight loss, palpitations, and goiter. Results of thyroid function tests revealed hyperthyroidism (free thyroxine, 3.42 ng/dL; thyroid stimulating hormone [TSH], <0.01 nIU/mL; triiodothyronine, 3.99 ng/mL). Results of tests for autoantibodies were positive for the antimicrosome antibody and TSH-binding inhibitory immunoglobulin, but negative for the antithyroglobulin antibody and antinuclear antibody. He was treated with methimazole, and his symptoms improved. The patient has been disease free for 39 months after IST and 9 months after methimazole treatment. This case report suggests that although rare, rabbit ATG may have implications in the pathogenesis of autoimmune hyperthyroidism. Our findings suggest that thyroid function tests should be incorporated in the routine follow-up of SAA patients treated with ATG.

• 한국동물생명공학회지
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• 제37권3호
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• pp.169-175
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• 2022

Bovine mammary epithelial (MAC-T) cells are commonly used to study mammary gland development and mastitis. Lipopolysaccharide is a major bacterial cell membrane component that can induce inflammation. Autophagy is an important regulatory mechanism participating in the elimination of invading pathogens. In this study, we evaluated the mechanism underlying bacterial mastitis and mammary cell death following lipopolysaccharide treatment. After 24 h of 50 ㎍/mL lipopolysaccharide treatment, a significant decrease in the proliferation rate of MAC-T cells was observed. However, no changes were observed upon treatment of MAC-T cells with 10 ㎍/mL of lipopolysaccharide for up to 48 h. Thus, upon lipopolysaccharide treatment, MAC-T cells exhibit dose-dependent effects of growth inhibition at 10 ㎍/mL and death at 50 ㎍/mL. Treatment of MAC-T cells with 50 ㎍/mL lipopolysaccharide also induced the expression of autophagy-related genes ATG3, ATG5, ATG10, ATG12, MAP1LC3B, GABARAP-L2, and BECN1. The autophagy-related LC3A/B protein was also expressed in a dose-dependent manner upon lipopolysaccharide treatment. Based on these results, we suggest that a high dose of bacterial infection induces mammary epithelial cell death related to autophagy signals.

• Biomolecules & Therapeutics
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• 제21권1호
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• pp.21-28
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• 2013

Microglia play a role in maintaining and resolving brain tissue homeostasis. In pathological conditions, microglia release pro-inflammatory cytokines and cytotoxic factors, which aggravate the progression of neurodegenerative diseases. Autophagy pathway might be involved in the production of pro-inflammatory cytokines and cytotoxic factors in microglia, though details of the mechanism remain largely unknown. In the present study, we examined the role of the autophagy pathway in activated BV2 microglia cells. In BV2 cells, rapamycin treatment activated the formation of anti-LC3-labeled autophagosomes, whereas the ATG5 depletion using siRNA-ATG5 prevented the formation of LC3-labeled autophagosomes, indicating that BV2 cells exhibit an active classical autophagy system. When treated with LPS, BV2 cells expressed an increase of anti-LC3-labeled dots. The levels of LC3-labeled dots were not suppressed, instead tended to be enhanced, by the inhibition of the autophagy pathway with siRNA-ATG5 or wortmannin, suggesting that LPS-induced LC3-labeled dots in nature were distinct from the typical autophagosomes. The levels of LPS-induced expression of iNOS and IL6 were suppressed by treatment with rapamycin, and conversely, their expressions were enhanced by siRNA-ATG5 treatment. Moreover, the activation of the autophagy pathway using rapamycin inhibited cell death of LPS-stimulated microglia. These results suggest that although microglia possess a typical autophagy pathway, the glial cells express a non-typical autophagy pathway in response to LPS, and the activation of the autophagy pathway suppresses the expression of iNOS and IL6, and the cell death of LPS-stimulated microglia.

• Biomolecules & Therapeutics
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• 제30권4호
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• pp.348-359
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• 2022

Gastric adenocarcinoma is among the top causes of cancer-related death and is one of the most commonly diagnosed carcinomas worldwide. Benzyl isothiocyanate (BITC) has been reported to inhibit the gastric cancer metastasis. In our previous study, BITC induced apoptosis in AGS cells. The purpose of the present study was to investigate the effect of BITC on autophagy mechanism in AGS cells. First, the AGS cells were treated with 5, 10, or 15 μM BITC for 24 h, followed by an analysis of the autophagy mechanism. The expression level of autophagy proteins involved in different steps of autophagy, such as LC3B, p62/SQSTM1, Atg5-Atg12, Beclin1, p-mTOR/mTOR ratio, and class III PI3K was measured in the BITC-treated cells. Lysosomal function was investigated using cathepsin activity and Bafilomycin A1, an autophagy degradation stage inhibitor. Methods including qPCR, western blotting, and immunocytochemistry were employed to detect the protein expression levels. Acridine orange staining and omnicathepsin assay were conducted to analyze the lysosomal function. siRNA transfection was performed to knock down the LC3B gene. BITC reduced the level of autophagy protein such as Beclin 1, class III PI3K, and Atg5-Atg12. BITC also induced lysosomal dysfunction which was shown as reducing cathepsin activity, protein level of cathepsin, and enlargement of acidic vesicle. Overall, the results showed that the BITC-induced AGS cell death mechanism also comprises the inhibition of the cytoprotective autophagy at both initiation and degradation steps.

• Journal of Plant Biology
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• 제38권1호
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• pp.107-113
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• 1995

pRLYS1 containing intact rbcL gene of maize (Zea mays L. cv Golden X Bantam T-51; Zm-A) was digested with several restriction enzymes to construct subcones carrying promoter region of rbcL. The DNA fragments of 0.20, 0.19, 0.92 and 1.55 kb among the EcoRI digests, the EcoRI-DdeI digests, the AvaI digests and the EcoRI-BamHI digests of pRLYS1 were subcloned into pBluscriptSK＋and named pRLPS2, pRLPS3, pRLPS14 and pRLPS35, respectively. Four subclones contain the 1.92 kb portion from 136 nucleotide downstream to 1780 nucleotide upstream from the ATG initiation codon of rbcL gene. pRLPS2 (-29 to -229) and pRLPS3 (-239 to -420 from the ATG) were sequenced. When nucleotide sequence of Zm-A was compared with sequence of rbcL promoter region of a different cultivar of maize (Zea mays L. cv WFG TMS X BS7; Zm-B), the difference rate between two cultivars was 4.3%. The mean of sequence divergence between Zm-A and three grass species in the same tribe, Andropogoneae, in the upstream region from 29 to 420 of ATG was 1.8%, whereas between Zm-B and above-mentioned three species was 5.4%. Therefore, Zm-A seems to evolutionarily closer to three other species in Andropogoneae tribe than Zm-B is.