Effects of Edta on the Electronic Properties of Passive Film Formed on Fe-20Cr In pH 8.5 Buffer Solution

Cho, EunAe,Kwon, HyukSang,Bernard, Frederic 한국부식방식학회 2003 Corrosion Science and Technology Vol.2 No.4

The electronic properties of the passive film formed on Fe-20Cr ferritic stainless steel in pH 8.5 buffer solution containing 0.05 M EDTA (ethylene diammine tetraacetic acid) were examined by the photocurrent measurements and Mott-Schottky analysis for the film. XPS depth profile for the film demonstrated that Cr content in the outermost layer of the passive film was higher in the solution with EDTA than that in the solution without EDTA, due to selective dissolution of Fe by EDTA. In the solution with EDTA, the passive film showed characteristics of an amorphous or highly disordered n-type semiconductor. The band gap energies of the passive film are estimated to be ∼ 3.0 eV, irrespective of film formation potential from 0 to 700 mV_(SCE) and of presence of EDTA. However, the donor density of the passive film formed in the solution with EDTA is much higher than that formed in the solution without EDTA, due to an increase in oxygen vacancy resulted ti-om the dissolution of Fe-oxide in the outermost layer of the passive film. These results support the proposed model that the passive film formed on Fe-20Cr in pH 8.5 buffer solution mainly consists of Cr-substituted γ-Fe₂0₃.

Poster Session : PS 1003 ; Lactulose Breath Test as Prognostic Factor in Irritable Bowel Syndrome

( Eunae Cho ),( Jong Sun Rew ),( Hyun Soo Kim ),( Chang Hwan Park ),( Seon Young Park ),( Sung Kyu Choi ) 대한내과학회 2014 대한내과학회 추계학술대회 Vol.2014 No.1

Background: Traditional symptom-based therapies of irritable bowel syndrome (IBS) are directed at the relief of individual IBS symptoms. However, prognostic factors for responses to these treatments have not yet been well studied. The purpose of this study was to evaluate predictors for treatment response in patients with IBS. Methods: A total of 183 patients diagnosed with IBS according to Rome III criteria and underwent lactulose breath test (LBT) from October 2010 to June 2014 were reviewed retrospectively. All participants had checked global IBS symptom questionnaire on the day of the LBT. Overall improvement of global IBS symptoms was reassessed after 4 weeks of treatment. Results: Sixty-one subjects (33.3%) were classified as diarrhea-predominant IBS (IBS-D), 38 (20.8%) as constipation-predominant IBS (IBS-C), 17 (9.3%) as mixed-symptoms IBS (IBS-M), and 67 (36.6%) as unspecifi ed type IBS (IBS-U). LBT results were not signifi cantly different in relation to IBS subtypes. One hundred and nineteen patients (65%) had positive LBT, while 64 patients (35%) had negative LBT. Among the 119 patients with positive LBT, overall symptom improvement was observed in 91 patients (76.5%). Subjects with underlying psychological problems were less likely to have symptom improvement (4/28 vs. 3/91 p=0.031). High basal hydrogen level (>20 ppm) was more frequent in the subjects without symptom improvement (6/28 vs. 6/91, p=0.023). However, underlying psychological problems and high basal hydrogen level were not signifi cantly associated with poor treatment response in patients with negative LBT. Conclusions: High basal hydrogen production correlates with poor treatment response in patients with IBS and positive LBT. This result suggests that LBT can be used as a tool for prediction of treatment response in patients with IBS and positive LBT.

Therapeutic implications of cancer epithelial-mesenchymal transition (EMT)

Eunae Sandra Cho,Hee Eun Kang,Nam Hee Kim,Jong In Yook 대한약학회 2019 Archives of Pharmacal Research Vol.42 No.1

The epithelial-mesenchymal transition (EMT)comprises an essential biological process involving cancer progression as well as initiation. While the EMT has been regarded as a phenotypic conversion from epithelial to mesenchymal cells, recent evidence indicates that it plays a critical role in stemness, metabolic reprogramming, immune evasion and therapeutic resistance of cancer cells. Interestingly, several transcriptional repressors including Snail (SNAI1), Slug (SNAI2) and the ZEB family constitute key players for EMT in cancer as well as in the developmental process. Note that the dynamic conversion between EMT and epithelial reversion (mesenchymal-epithelial transition, MET) occurs through variable intermediate-hybrid states rather than being a binary process. Given the close connection between oncogenic signaling and EMT repressors, the EMT has emerged as a therapeutic target or goal (in terms of MET reversion) in cancer therapy. Here we review the critical role of EMT in therapeutic resistance and the importance of EMT as a therapeutic target for human cancer.

Impact of Scope Exchange from a Long Single Balloon Enteroscope to a Gastroscope during Enteroscopy-Assisted Endoscopic Retrograde Cholangiopancreatography in Patients with Surgically Altered Anatomy

Cho Eunae,Park Chang Hwan,Kim Youngjung,Cho Seo Yeon 거트앤리버 소화기연관학회협의회 2022 Gut and Liver Vol.16 No.2

Background/Aims: Endoscopic retrograde cholangiopancreatography (ERCP) in patients with surgically altered anatomy (SAA) is challenging to gastrointestinal endoscopists. The aim of this study was to evaluate the impact of scope exchange from a long single balloon enteroscope (SBE) to a gastroscope during SBE-assisted ERCP (SBE-ERCP) in patients with SAA. Methods: Patients who underwent SBE-ERCP between February 2019 and October 2020 were retrospectively identified. Intubation success, scope exchange success, cannulation success, and therapeutic success were analyzed along with complications. Results: Fifty-six patients with various SAAs underwent SBE-ERCP procedures, including Billroth II subtotal gastrectomy (B-II, n=13), pylorus-preserving pancreato-duodenectomy (PPPD, n=6), Roux-en-Y hepaticojejunostomy (REY HJ, n=4), and total gastrectomy with REY anastomosis (TG REY, n=33). Overall intubation, cannulation, and therapeutic success rates were 89.3%, 82.1%, and 82.1%, respectively. Therapeutic success rates did not differ significantly among the type of SAA. Successful scope exchange rate after successful intubation was significantly higher in native papilla (B-II and TG REY, 83.3%, 35/42) compared to bilioenteric anastomosis (PPPD and REY HJ, 0%, 0/8, p<0.001). Intubation success, scope exchange, and cannulation success were associated with therapeutic success (p<0.001). In multivariate analysis, successful scope exchange was the only factor related to cannulation success (p=0.02). The major complication rate was 1.8% (one perforation). Conclusions: SBE-ERCP is a safe and effective procedure to treat biliary problems in patients with SAA. Successful scope exchange may lead to higher therapeutic success by way of cannulation success.

A Study on the Electronic Properties of Passive Film Formed on Fe-20Cr by Photoelectrochemical and Mott-Schottky Analysis

Cho, EunAe,Kwon, HyukSang 한국부식방식학회 2002 Corrosion Science and Technology Vol.31 No.4

The electronic properties of passive film formed on Fe-2OCr stainless steel in pH 8.5 buffer solution were examined by the photocurrent measurements and Mott-Schottky analysis of the film. The passive film on Fe-20Cr exhibited an amorphous or highly disordered n-type semiconductor. The photocurrent spectrum for the passive films formed on Fe-20Cr was almost same in shape to that for the passive film of Fe except for the large difference in photocurrent intensity, which demonstrated that the passive film on Fe-2OCr is composed of Cr substituted r-Fe₂O₃,. However, the large difference in photocurrent intensity for passive film between Fe and Fe-2OCr was due presumably to the fact that Cr^3+ ions in passive film act as effective recombination sites of electron-hole pairs. The relatively high intensity of photocurrent and two linear regions on Mott-Schottky plot for the passive film formed at potentials in Cr-transpassive region was associated with Cr^6+ ions present in the film.

Properties and current applications of bacterial cyclic β-glucans and their derivatives

Cho, Eunae,Jeong, Daham,Choi, Youngjin,Jung, Seunho KLUWER ACADEMIC PUBLISHERS 2016 JOURNAL OF INCLUSION PHENOMENA AND MACROCYCLIC CHE Vol. No.

<P>Cyclic beta-glucans are unique constituents that are found in the periplasmic space and extracellular media of Agrobacterium, Rhizobium, Bradyrhizobium, Rhodobacter, Xanthomonas, and Ralstonia species. Based on their glycosidic linkages, they are classified into three groups composed of cyclic beta-(1,2), beta-(1,3)-beta-(1,6), and beta-(1,2)-alpha-(1,6) linked glucans. Their degrees of polymerization vary ranging from 10 to 40 glucose residues, and the backbone structure can be modified with non-sugar moieties. Since the macrocyclic oligosaccharides possess their own characteristics such as inherent three-dimensional structures, hydrogen bonding, and complex-forming abilities, various possible applications would be of interest in the field of green chemistry, separation science, pharmaceutical, and food industries. In this review, we have addressed the properties and current applications of bio-sourced cyclic beta-glucans and their derivatives.</P>

The Pentose Phosphate Pathway as a Potential Target for Cancer Therapy

( Eunae Sandra Cho ),( Yong Hoon Cha ),( Hyun Sil Kim ),( Nam Hee Kim ),( Jong In Yook ) 한국응용약물학회 2018 Biomolecules & Therapeutics(구 응용약물학회지) Vol.26 No.1

During cancer progression, cancer cells are repeatedly exposed to metabolic stress conditions in a resource-limited environment which they must escape. Increasing evidence indicates the importance of nicotinamide adenine dinucleotide phosphate (NADPH) homeostasis in the survival of cancer cells under metabolic stress conditions, such as metabolic resource limitation and therapeu-tic intervention. NADPH is essential for scavenging of reactive oxygen species (ROS) mainly derived from oxidative phosphoryla-tion required for ATP generation. Thus, metabolic reprogramming of NADPH homeostasis is an important step in cancer progres-sion as well as in combinational therapeutic approaches. In mammalian, the pentose phosphate pathway (PPP) and one-carbon metabolism are major sources of NADPH production. In this review, we focus on the importance of glucose flux control towards PPP regulated by oncogenic pathways and the potential therein for metabolic targeting as a cancer therapy. We also summarize the role of Snail (Snai1), an important regulator of the epithelial mesenchymal transition (EMT), in controlling glucose flux towards PPP and thus potentiating cancer cell survival under oxidative and metabolic stress.

A dimyristoyl phosphatidylcholine/polydiacetylene biomimetic assembly for the selective screening of progesterone

Cho, Eunae,Hu, Yiluo,Choi, Youngjin,Jung, Seunho Elsevier 2018 Journal of industrial and engineering chemistry Vol.63 No.-

<P><B>Abstract</B></P> <P>We have reported a hybrid polymer composite, consisting of a supramolecular assembly of polydiacetylene (PDA) and phospholipid, that undergoes chromatic and fluorogenic changes after specific interactions with progesterone, the pregnancy hormone. Progesterone was selectively detected among 10 steroids by the mixed polymer of 1,2-dimyristoyl-sn-glycero-3-phosphocholine and PDA at an optimized ratio of 1:9. The triggering effect of progesterone on the membrane mimetic system were investigated using UV–vis, fluorescence, circular dichroism spectroscopy, Raman scattering, dynamic light scattering, transmission electron microscopy, and computational method. These results offer insight into self-assembly disruption and membrane targeting antibiotics as well as PDA-based sensing technology.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A DMPC/PDA biomimetic assembly is reported as a colorimetric and fluorescent sensory platform for progesterone. </LI> <LI> Progesterone was detected exclusively among 10 different steroid compounds using the biomimetic membrane interface. </LI> <LI> The triggering effect of progesterone on DMPC/PDA membrane mimetic system was evaluated using various analytical tools. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Chiral Separation of Hesperetin and Hesperetin-O-glycoside in Capillary Electrophoresis Using Microbial β-1,2-Glucans

Eunae Cho,Yukyoung Jeon,정선호 대한화학회 2009 Bulletin of the Korean Chemical Society Vol.30 No.8

Solubility Enhancement of Flavonols in the Inclusion Complex with Thioether-bridged Dimeric β-Cyclodextrins

Cho, Eunae,Jeong, Daham,Paik, Hyun-Dong,Jung, Seunho Korean Chemical Society 2014 Bulletin of the Korean Chemical Society Vol.35 No.8

Dimeric ${\beta}$-cyclodextrin linked by a thioether bridge was synthesized from a reaction of mono-6-iodo-6-deoxy-${\beta}$-cyclodextrin with sodium sulfide, and the structure was analyzed using nuclear magnetic resonance spectroscopy and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The effects of thioether-bridged dimeric ${\beta}$-CD on the aqueous solubility of flavonols (myricetin, quercetin, and kaempferol) were investigated by ultraviolet-visible spectroscopy. The aqueous solubility of myricetin, quercetin, and kaempferol were enhanced 33.6-, 12.4-, and 10.5-fold following the addition of 9 mM of thioether-bridged dimeric ${\beta}$-CD. In comparison, the aqueous solubility of myricetin, quercetin, and kaempferol were enhanced 5.4-, 3.3-, and 2.7-fold using the same concentration of monomeric ${\beta}$-cyclodextrin. Furthermore, the formation of flavonol/thioether-bridged dimeric ${\beta}$-CD inclusion complexes was confirmed with nuclear magnetic resonance, Fourier-transform infrared spectroscopy, differential scanning calorimetry, and scanning electron microscopy. The results showed that the nature of the complexes significantly differed from that of free flavonols. Herein, we suggest that the thioether-bridged dimeric ${\beta}$-CD can act as an effective complexing agent for flavonols.