A Study of Oxidation Resistant Coating on TiAl alloys by Cr Evaporation and Pack Cementation

Jung, DongJu,Jung, HwanGyo,Kim, KyooYoung 한국부식방식학회 2002 Corrosion Science and Technology Vol.31 No.1

A Cr+Al-type composite coating is applied to improve the properties of aluminide coating layers, TiAl₃, formed on TiAl alloys. This method is performed by Cr evaporation on the TiAl-XNb(X=1,6at%) substrate followed by pack aluminizing. The coating layer formed by the composite coating process consists of the outer layer of AI₄Cr and the inner layer of TiAl₃regardless of the Nb content. However, these coating layers are transtormed to Ti(AI,Cr)₃ layers with Ll₂ structures during oxidation. In particular, as Nb content increases, the grain size of the inner TiAIi layer becomes smaller and the diffusion rate of Cr increases after oxidation. Faster formation of a Ti(AI,Cr)₃ layer with an Ll₂ structure through Nh addition is more effective to improve cracking resistance at the beginning of ohidation of TiAl alloys. However, growth of Ti(Al,Cr)₃fomied on the coating layer becomes slower as the Nh content in the coating layer is increased. As a result, the addition of a large amount of Nb to composite coating layer is not desirable due to poor ductility ofthe coating layer. A Ti (AI,Cr)₃ layer with an Ll₂ structure developed during oxidation showed much better ductility compared with other coating layers.

Wrenchnolol Derivative Optimized for Gene Activation in Cells

Jung, Dongju,Shimogawa, Hiroki,Kwon, Youngjoo,Mao, Qian,Sato, Shin-ichi,Kamisuki, Shinji,Kigoshi, Hideo,Uesugi, Motonari American Chemical Society 2009 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.131 No.13

<P>Naturally occurring transcription factors usually have two independent domains, a DNA-binding domain and an activation domain. In designing a synthetic small molecule that mimics a transcription factor, each of the two domains needs to be replaced by small-molecule counterparts. Results of the present study show that derivatives of wrenchnolol, a synthetic molecule that interacts with Sur-2 coactivator, serve as activation modules and stimulate gene transcription in vitro and in cells when tethered to a DNA-binding molecule. Thirteen derivatives of wrenchnolol were chemically synthesized and tested for their ability to activate transcription in vitro and in cells. When tethered to the GAL4 DNA-binding domain, one derivative increased transcription of a GAL4-responsive reporter gene in cells 9-fold. This optimized derivative also induced up to 45% myogenesis of C2C12 cells when tethered to the DNA-binding domain of myogenic transcription factor MyoD. This optimized derivative may serve as a starting point for designing biological tools or components of fully synthetic transcription factors that permit selective up-regulation of genes.</P>

The Clinicopathological Characteristics of Palpable and Non-palpable Breast Cancer

Dongju Kim,Soo Jung Lee,Byung Kyun Ko,Han-Byoel Lee,Jung Han Yoon,Seok Won Lee,전예원,Bong Kyun Kim,Jina Lee,선우영 한국유방암학회 2020 Journal of Breast Disease Vol.8 No.2

Purpose: Palpability is known to be a poor prognostic factor for breast cancer. The present study analyzed the clinicopathological characteristics and outcomes of palpable and nonpalpable breast cancers using big data. Methods: Between January 2005 and May 2019, a total of 15,141 patients were enrolled. All patients were diagnosed with invasive ductal carcinomas. Patients with unclear medical records, multiple tumors, bilateral breast cancers, inflammatory breast cancers, inoperable breast cancers and distant metastasis were excluded. Patients were divided into the palpable and nonpalpable breast cancer groups based on physicians’ clinical examinations. The clinicopathological characteristics and disease-specific survivals (DSS) were analyzed. Results: Patients with palpable breast cancers were younger, had larger tumors, and higher tumor-node-metastasis stage (p<0.001) than patients with nonpalpable breast cancers. Palpable breast cancer cases had higher rates of lympho-vascular invasion, higher histologic and nuclear grades than nonpalpable breast cancer cases (p<0.001). The positive proportion of hormone receptor was higher in the nonpalpable breast cancer group than in the palpable breast cancer group, but that of human epidermal growth factor receptor 2 was higher in the palpable breast cancer group than in the nonpalpable breast cancer group (p<0.001). The Ki-67 index was higher in the palpable breast cancer group than in the nonpalpable breast cancer group (p<0.001). Total mastectomy and axillary dissection were performed more frequently in the palpable breast cancer group than in the nonpalpable breast cancer group (p<0.001). Adjuvant chemotherapy was administered more frequently in the palpable breast cancer group than in the nonpalpable breast cancer group. However, radiotherapy and hormonal therapy were performed more frequently in nonpalpable breast cancer group than in the nonpalpable breast cancer group (p<0.001). According to a multivariate analysis, younger age, lower body mass index, larger tumor size, tumor location, higher stage, higher histologic grade and higher Ki-67 index were associated with palpability (p<0.001). DSS was significantly lower in the palpable breast cancer group than in the nonpalpable breast cancer group (p<0.001). Conclusion: Palpable breast cancers tend to be triple negative breast cancers and have higher histologic grade and, Ki-67 index and worse prognosis than nonpalpable breast cancers. Therefore, based on the results of the present study, treating palpable breast cancers requires careful attention.

Mycobacterium tuberculosis DNA Detection and Molecular Drug Susceptibility Test in AFB-stained Sputum Slides

Dongju Jung,Hyeyoung Lee,Sangjung Park 대한의생명과학회 2016 Biomedical Science Letters Vol.22 No.1

Tuberculosis (TB) remains an unsolved community health problem since identification of its causing microorganism called Mycobacterium tuberculosis (MTB) by Robert Koch in 1882. Annually, eight million TB cases are newly reported and 2~3 million patients die from TB. Pulmonary TB is highly infectious and untreated pulmonary TB patients are believed to infect >10 people in a year. The conventional methods for diagnosis of TB are chest X-ray and isolation of the causing microorganisms from patient specimens. Screening of TB is conducted with smeared sputum in slides, and TB is confirmed by identification of MTB in cultured specimens. One of the fatal pitfalls of screening detection for smeared sputum is that it is impossible to distinguish MTB and other acid-fast bacilli (AFB) because they are stained equally with Ziehl-Neelsen (ZN) stain. Culture of MTB is the most reliable method for diagnosis of TB but it takes 4~8 weeks. In this report, we suggest a fast and highly-reliable MTB detection method that distinguishes AFB in sputum samples. Purified DNA from the AFB stained slide samples offered by The Korean Institute of Tuberculosis were used to detect infected MTB in patients. PCR, real-time PCR and reverse blot hybridization assay (REBA) methods were applied to purified DNA. Conclusively, the real-time PCR method was confirmed to produce high sensitivity and we were able to further detect drug-resistant MTB with REBA.

Association Analysis between Genes’ Variants for Regulating Mitochondrial Dynamics and Fasting Blood Glucose Level

Dongju Jung,Hyun-Seok Jin 대한의생명과학회 2016 Biomedical Science Letters Vol.22 No.3

Maintenance of fasting blood glucose levels is important for glucose homeostasis. Disruption of feedback mechanisms are a major reason for elevations of glucose level in blood, which is a risk factor for type 2 diabetes mellitus that is mainly caused by malfunction of pancreatic beta-cell and insulin. The fasting blood glucose level has been known to be influenced by genetic and environmental factors. Mitochondria have many functions for cell survival and death: glucose metabolism, fatty acid oxidation, ATP generation, reactive oxygen species (ROS) metabolism, calcium handling, and apoptosis regulation. In addition to these functions, mitochondria change their morphology dynamically in response to multiple signals resulting in fusion and fission. In this study, we aimed to examine association between fasting blood glucose levels and variants of the genes that are reported to have functions in mitochondrial dynamics, fusion and fission, using a cohort study. A total 416 SNPs from 36 mitochondrial dynamics genes were selected to analyze the quantitative association with fasting glucose level. Among the 416 SNPs, 4 SNPs of PRKACB, 13 SNPs of PPP3CA, 6 SNPs of PARK2, and 3 SNPs of GDAP1 were significantly associated. In this study, we were able to confirm an association of mitochondrial dynamics genes with glucose levels. To our knowledge our study is the first to identify specific SNPs related to fasting blood glucose level.

Association of the TREML2 and HTR1E Genetic Polymorphisms with Osteoporosis

Dongju Jung,Hyun-Seok Jin 대한의생명과학회 2015 Biomedical Science Letters Vol.21 No.4

Osteoporosis is one of the diseases caused by accumulation of effects from complex interactions between genetic and environmental factors. Aging is the major cause for osteoporosis, which normally increases skeletal fragility and bone fracture especially among the elder. "Omics" refers to a specialized research field dealing with high-throughput biological data, such as genomics, transcriptomics, proteomics or metabolomics. Integration of data from multi-omics has been approved to be a powerful strategy to colligate biological phenomenon with multiple aspects. Actually, integrative analyses of "omics" datasets were used to present pathogenesis of specific diseases or casual biomarkers including susceptible genes. In this study, we evaluated the proposed relationship of novel susceptible genes (TREML2, HTR1E, and GLO1) with osteoporosis, which genes were obtained using multi-omics integration analyses. To this end, SNPs of the susceptible genes in the Korean female cohort were analyzed. As a result, one SNP of HTR1E and five SNPs of TREML2 were identified to associate with osteoporosis. The highest significant SNP was rs6938076* of TREML2 (OR=0.63, CI: 0.45~0.89, recessive P=0.009). Consequently, the susceptible genes identified through the multi-omics analyses were confirmed to have association with osteoporosis. Therefore, multi-omics analysis might be a powerful tool to find new genes associated with a disease. We further identified that TREML2 has more associated with osteoporosis in females than did HTR1E.

Construction of a Cell-Adhesive Nanofiber Substratum by Incorporating a Small Molecule

Dongju Jung 대한의생명과학회 2013 Biomedical Science Letters Vol.19 No.1

Electrospun nanofibers are being widely used as a substratum for mammalian cell culture owing to their structural similarity to collagen fibers found in extracellular matrices of mammalian cells and tissues. Especially, development of diverse synthetic polymers has expanded use of electrospun nanofibers for constructing cell culture substrata. Synthetic polymers have several benefits comparing to natural polymer for their structural consistency, low cost, and capability for blending with other polymers or small molecules to enhance their structural integrity or add biological functions. PMGI (polymethylglutarimide) is one of the synthetic polymers that produced a rigid nanofiber that enables incorporation of small molecules, peptides, and gold nanoparticles through co-electrospinning process, during which the materials are fixed without any chemical modifications in the PMGI nanofibers by maintaining their activities. Using the phenomenon of PMGI nanofiber, here I introduce a construction method of a nanofiber substratum having cell-affinity function towards a pluripotent stem cell by incorporating a small molecule in the PMGI nanofiber.

Gene Expression Analysis from the Normal Stomach Cells Treated with a Cancer Inducer N-methyl-N"-nitro-N-nitrosoguanidine, MNNG

Dongju Jung,Yoonjung Cho,Tae Ue Kim,Sang-Hee Jeong 대한의생명과학회 2017 Biomedical Science Letters Vol.23 No.1

N-methyl-N"-nitro-N-nitrosoguanidine (MNNG) is a carcinogen made of modified guanine on which alkyl group is added on 6th oxygen. It has been used for inducing different types of cancers experimentally in vivo and in vitro. Stomach cancer might be the best well established particular cancer induced with MNNG. Comparative analysis of gene expression between normal stomach cell and MNNG-treated stomach cell could give much information to understand cancer formation in stomach. To this end, normal human stomach cells HS738 were treated with DMSO or MNNG. Genetic comparison was conducted with purified RNA from the treated cells for 6 hours or 24 hours. Total 13 genes were selected based on their high induction folds and comprehensible function to cancer formation. Some of the genes were cancer-promoting whereas the others were anti-cancer genes. These results could give important information of genetic changes in stomach cells during MNNG-induced stomach cancer formation.

2차냉매로서 상변화물질을 사용한 냉동시스템의 특성에 관한 연구

정동주(Dongju Jung),최병권(Byoungkwon Choi),최은수(Eunsoo Choi),남기영(Giyoung Nam),박인규(Ingyu Park) 대한설비공학회 2004 대한설비공학회 학술발표대회논문집 Vol.2004 No.-

아이스 슬러리의 수송 및 냉열이용에 관한 연구

정동주(Dongju Jung),조봉현(Bonghyun Cho),최은수(Eunsoo Choi) 대한설비공학회 2001 대한설비공학회 학술발표대회논문집 Vol.2001 No.-