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Search Results: 1 - 10 of 25956 matches for " Yong-Kook Kwon "
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Analysis of proteomic profiling of mouse embryonic stem cells derived from fertilized, parthenogenetic and androgenetic blastocysts  [PDF]
Xiang-Shun Cui, Xing-Hui Shen, Chang-Kwon Lee, Yong-Kook Kang, Teruhiko Wakayama, Nam-Hyung Kim
Stem Cell Discovery (SCD) , 2011, DOI: 10.4236/scd.2011.11001
Abstract: Embryonic stem cells (ESCs) are derived from the inner cell mass (ICM) of preimplantation embryos. ESCs exhibit true pluripotency, i.e., the ability to differentiate into cells of all three germ layers in the developing embryo. We used 2-DE MALDI-TOF/TOF to identify differentially expressed proteins among three types of mouse embryonic stem cells (ESCs) derived from ferti-lized, parthenogenetic, and androgenetic (fESC, pESC and aESC, respectively) blastocysts. We detected more than 800 proteins on silver- stained gels of whole protein extracts from each type of ESC. Of these, 52 differentially expressed proteins were identified by the MALDI–TOF/TOF analyzer, including 32 (fESCs vs. pESCs), 28 (fESCs vs. aESCs) and 17 (pESCs vs. aESCs) prominent proteins with significantly higher or lower expression relative to the comparison cells. Among the 32 proteins from fESCs, 12 were significantly increased in expression and 20 were reduced in expression in fESCs com-pared with pESCs. Similarly, 10 of 28 and 8 of 17 proteins were more highly expressed in fESCs and pESCs compared with aESCs, respectively. In contrast, 18 of 28 and 9 of 17 proteins were reduced in expression in fESCs and pESCs compared with aESCs, respectively. Of the eight protein candidates in fESCs, four were in-creased and four were decreased in expression relative to both pESCs and aESCs in the 2-DE analysis. Differential expression of these pro-teins were confirmed by mRNA expression analysis using real time RT-PCR. For three pro-teins, ANXA5, CLIC1 and SRM, Western blot analysis corroborated the expression patterns indicated by the 2-DE results. ANXA5 and CLIC1 were increased in expression and SRM was de-creased in expression in fESCs compared with both pESCs and aESCs. The differentially ex-pressed proteins identified in the present study warrant further investigation towards the goal of their potential application in ESC therapy.
1H NMR-Based Metabolite Profiling of Plasma in a Rat Model of Chronic Kidney Disease
Ju-Ae Kim, Hyo-Jung Choi, Yong-Kook Kwon, Do Hyun Ryu, Tae-Hwan Kwon, Geum-Sook Hwang
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0085445
Abstract: Chronic kidney disease (CKD) is characterized by the gradual loss of the kidney function to excrete wastes and fluids from the blood. 1H NMR-based metabolomics was exploited to investigate the altered metabolic pattern in rats with CKD induced by surgical reduction of the renal mass (i.e., 5/6 nephrectomy (5/6 Nx)), particularly for identifying specific metabolic biomarkers associated with early of CKD. Plasma metabolite profiling was performed in CKD rats (at 4- or 8-weeks after 5/6 Nx) compared to sham-operated rats. Principle components analysis (PCA), partial least squares-discriminant analysis (PLS-DA) and orthogonal partial least squares-discriminant analysis (OPLS-DA) score plots showed a significant separation between the groups. The resulting metabolic profiles demonstrated significantly increased plasma levels of organic anions, including citrate, β-hydroxybutyrate, lactate, acetate, acetoacetate, and formate in CKD. Moreover, levels of alanine, glutamine, and glutamate were significantly higher. These changes were likely to be associated with complicated metabolic acidosis in CKD for counteracting systemic metabolic acidosis or increased protein catabolism from muscle. In contrast, levels of VLDL/LDL (CH2)n and N-acetylglycoproteins were decreased. Taken together, the observed changes of plasma metabolite profiles in CKD rats provide insights into the disturbed metabolism in early phase of CKD, in particular for the altered metabolism of acid-base and/or amino acids.
dSETDB1 and SU(VAR)3–9 Sequentially Function during Germline-Stem Cell Differentiation in Drosophila melanogaster
Jeongheon Yoon, Kyu-Sun Lee, Jung Sun Park, Kweon Yu, Sang-Gi Paik, Yong-Kook Kang
PLOS ONE , 2008, DOI: 10.1371/journal.pone.0002234
Abstract: Germline-stem cells (GSCs) produce gametes and are thus true “immortal stem cells”. In Drosophila ovaries, GSCs divide asymmetrically to produce daughter GSCs and cystoblasts, and the latter differentiate into germline cysts. Here we show that the histone-lysine methyltransferase dSETDB1, located in pericentric heterochromatin, catalyzes H3-K9 trimethylation in GSCs and their immediate descendants. As germline cysts differentiate into egg chambers, the dSETDB1 function is gradually taken over by another H3-K9-specific methyltransferase, SU(VAR)3–9. Loss-of-function mutations in dsetdb1 or Su(var)3–9 abolish both H3K9me3 and heterochromatin protein-1 (HP1) signals from the anterior germarium and the developing egg chambers, respectively, and cause localization of H3K9me3 away from DNA-dense regions in most posterior germarium cells. These results indicate that dSETDB1 and SU(VAR)3–9 act together with distinct roles during oogenesis, with dsetdb1 being of particular importance due to its GSC-specific function and more severe mutant phenotype.
Notch signaling is required for maintaining stem-cell features of neuroprogenitor cells derived from human embryonic stem cells
Sun-Mi Woo, Janghwan Kim, Hyo-Won Han, Jung-Il Chae, Mi-Young Son, Sunwha Cho, Hyung-Min Chung, Yong-Mahn Han, Yong-Kook Kang
BMC Neuroscience , 2009, DOI: 10.1186/1471-2202-10-97
Abstract: From hESCs, we derived NESs, the in-vitro version of brain-derived neurospheres. NES formation was confirmed by increased levels of various NSC marker genes and the emergence of rosette structures in which neuroprogenitors are known to reside. We found that Notch signaling, which maintains stem cell characteristics of in-vivo-derived neuroprogenitors, is active in these hESC-derived NESs, similar to their in-vivo counterpart. Expression levels of Notch signaling molecules such as NICD, DLLs, JAG1, HES1 and HES5 were increased in the NESs. Inhibition of the Notch signaling by a γ-secretase inhibitor reduced rosette structures, expression levels of NSC marker genes and proliferation potential in the NESs, and, if combined with withdrawal of growth factors, triggered differentiation toward neurons.Our results indicate that the hESC-derived NESs, which share biochemical features with brain-derived neurospheres, maintain stem cell characteristics mainly through Notch signaling, which suggests that the hESC-derived NESs could be an in-vitro model for in-vivo neurogenesis.Neural stem cells (NSCs), which have properties of self-renewal and differentiation into neurons and glias, are usually isolated from fetal and adult brains in the form of floating clonal derivatives of the NSCs placed in culture, known as neurospheres (NSs) [1-3]. NSCs have the potential to be used in cell replacement therapy for neural disorders such as Parkinson's disease and Alzheimer's disease as well as other neurological disorders including spinal cord injuries [4]. For therapy, maintenance and expansion of the NSCs are necessary to provide sufficient amount of cells for patients to be treated.Human NSCs can be obtained from brains and from human embryonic stem cells (hESCs) by a step-wise differentiation procedure [5-8], and such hESC-derived NSCs are usually cultured as NS-like aggregates. However, the NS-like aggregates, also called neuroectodermal spheres (NESs; [9]), differ from the NSs in tha
The EPHX1 rs1051740 Polymorphism Is Associated with Childhood Acute Lymphoblastic Leukemia in a Korean Population  [PDF]
Hee Nam Kim, Nan Young Kim, Li Yu, Il-Kwon Lee, Min-Ho Shin, Hee Jo Baek, Hoon Kook, Hyeoung-Joon Kim
Advances in Bioscience and Biotechnology (ABB) , 2014, DOI: 10.4236/abb.2014.57080
Abstract:

Microsomal epoxide hydrolase (EPHX1) is involved in the activation and detoxification of exogenous chemicals. Genetic polymorphisms in EPHX1 have been associated with the development of leukemia. To investigate an association between single-nucleotide polymorphisms (SNPs) of EPHX1 and risk factors for childhood acute lymphoblastic leukemia (ALL) in Korean children, we genotyped two SNPs, Tyr113His (rs1051740) and His139Arg (rs2234922) in 185 childhood ALL cases and 536 healthy controls. Genotyping for these two SNPs was performed by simplex pyrosequencing assay and high-resolution melt analysis, respectively. We found that the Tyr113His genotype was associated with a decreased risk of childhood ALL (odds ratio, OR = 0.64, 95% confidence interval, CI = 0.43 - 0.93; p = 0.02). There was no association between His139Arg and the combined genotypes and the risk of childhood ALL. These results suggest that the EPHX1 113TyrHis genotype may protect against leukemogenesis in childhood.

Surgical Technique Affects the Incidence of Marginal Ulceration after Roux-en-Y in Gastric Bypass  [PDF]
Yong Kwon Lee, Corrigan McBride, Valerie Shostrom, Jon Thompson
Surgical Science (SS) , 2013, DOI: 10.4236/ss.2013.412A001
Abstract:

Background: Marginal ulceration (MU) is a recognized complication of Roux-en-Y gastric bypass (RYGB) surgery. While several possible risk factors have been reported, the mechanism of MU remains incompletely understood. The aim of this study was to compare the effect of surgical technique on the incidence of MU. Methods and Material: This was a retrospective study of 749 patients undergoing RYGB over a ten-year period with at least one year of follow-up. The diagnosis of MU was made based on clinical symptoms and confirmed by postoperative endoscopy (POE). We assessed four different gastric bypass (GBP) techniques: T1—Open, non-divided stomach, circular stapler, non-vagotomy (n = 332); T2—Open, divided stomach, circular stapler, vagotomy (n = 91); T3—Laparoscopic, divided, circular stapler, vagotomy (n = 152); T4—Laparoscopic, divided, linear stapler, vagotomy (n = 174). Results: The four groups were similar with respect to age and mean BMI. The frequency of POE was 16%, 25%, 28% and 27% in groups T1-T4 respectively (NS). The incidence of MU was significantly lower in T1 (2.1%) compared to T2 (5.5%), T3 (15.1%) and T4 (12.6%), p

General Guide for Korean Acupuncture & Moxibustion  [PDF]
Hyo-Jung Kwon, Yong-Suk Kim
Open Journal of Immunology (OJI) , 2015, DOI: 10.4236/oji.2015.53010
Abstract: As ancient Korean and Chinese dynasties held close relationships in politics and culture throughout history, the medicine of the two nations were developed in mutual influence. For instance, the current version of Lingshu, the second half of the Huangdineijing, was transcribed from The Bible of Acupuncture, which was brought to the Chinese Song dynasty from the Korean Koryo dynasty in 1092. While maintained a close relationship with traditional Chinese medicine, Korean medicine had continued to develop unique systems on its own over the history and established typical types of acupuncture methods, which are different from those of traditional Chinese medicine [1]. In the 17th century, a royal physician by the name of Dr. Heo Jun wrote Donguibogam, the first encyclopedia of Korean medicine in Korea. It remained to be a book of instruction for Korean Medicine Doctors. Another book called Donguisusebowon was published in 1901 on the basis of the theory of four constitutions by Dr. Lee Je-Ma at the end of the Chosun dynasty [2]. There were two other representative Korean acupuncture methods: Saam acupuncture and Constitutional acupuncture (Taeguek acupuncture). Theories of Korean acupuncture applied a summarized framework for each individual to diagnose a physical condition, explaining the biologic phenomena within the concept of constitutional medicine [1]. The diagnosis systems of several Korean acupuncture styles were focused on simplifying the understanding of the body’s core imbalances, and the resulting diagnosis enabled practitioners to devise therapeutic strategies that were based on constitutional energy traits. Saam acupuncture used 12 energy (or Qi) traits, mainly controlled by the 12 corresponding Meridians, that underlie diverse superficial biologic phenomena [2] [3]. It was suggested that these 12 energies determined the inclinations of the whole body, and they were targeted to recover the balance of the body’s constancy. Taegeuk acupuncture was identified by Sasang constitutional medicine according to the patient’s innate constitution. Sasang constitutional medicine identified four constitutions according to the individual’s inherent disparities among major Organ energies, expressed as the size of the Organs, all of which determined the physiologic characteristics of the individual patient and served as a major imbalance succeeding diverse pathologic processes. These constitutional traits were suggested to be the source of individual differences in apparently similar physiologic or pathologic reactions [2].
The Phenomenon of High Hardness Values on the S-Phase Layer of Austenitic Stainless Steel via Screen Plasma Nitriding Process  [PDF]
Sang-Gweon Kim, Kook-Hyun Yeo, Yong-Ki Cho, Jae-Hoon Lee, Masahiro Okumiya
Advances in Materials Physics and Chemistry (AMPC) , 2018, DOI: 10.4236/ampc.2018.86017
Abstract: The purpose of this study is to improve the surface properties of austenitic stainless steel using the double-folded electrode screen plasma nitriding (SPN) process. In general, the S-phase is well-known for its excellent properties such as improved hardness and wear resistance along with sustained corrosion resistance. The concentrated nitrogen via SPN process was injected to form S-phase with time at 713 K. This study was carried out under the conditions of 44 at% of nitrogen injection, which was higher than 25 at% known as the condition of no precipitation of S-phase formed by the SPN process, and 20 K higher than the maximum temperature without precipitation phase. The hardness analysis of stainless steel sample treated by the SPN process at 713 K showed a much higher value than the typical nitriding hardness at a depth of lower nitrogen than the maximum nitrogen concentration. The SPN 20 hr treated specimen showed the average value of 2339 HV while 40 hr showed the average value of 2215 HV. The result is attributed to the concentrated nitrogen formed in the SPN process reacting with the alloying elements contained in the base material to form fine precipitates
Clonal evolution of hepatitis B virus polymerase gene mutations during lamivudine-adefovir combination treatment
Soon Young Ko,Byung Kook Kim,So Young Kwon,Kyun-Hwan Kim
World Journal of Gastroenterology , 2012, DOI: 10.3748/wjg.v18.i44.6437
Abstract: AIM: To identify hepatitis B virus polymerase gene mutations during antiviral therapy using lamivudine-adefovir sequential monotherapy followed by lamivudine-adefovir combination therapy. METHODS: The patient cohort included four adult chronic hepatitis B patients who had undergone sequential monotherapy, first with lamivudine (LMV) and then, after developing viral breakthrough, with adefovir (ADV) therapy. All of the patients had non-response or viral breakthrough after LMV-ADV sequential monotherapy, which resulted in the switching of their antiviral regimen to LMV-ADV combination therapy. Eleven serum samples from the four patients who showed non-response to rescue LMV-ADV combination therapy were collected sequentially at a time before the antiviral treatment and then during the LMV monotherapy, ADV monotherapy, and LMV-ADV combination therapy. For the genotypic analysis, the whole 1310-bp polymerase gene region was amplified, cloned and sequenced. RESULTS: All patients had been previously treated with 100 mg of LMV once daily for a 15- to 26-mo period. The emergence of resistance mutations to LMV, such as rtM204V/I and/or rtL180M, were found in all patients. Their antiviral regimens were switched to ADV monotherapy as the second line treatment. All patients had viral breakthrough or non-response after the LMV-ADV sequential monotherapy. ADV-resistant mutations were detected after 13 to 19 mo of LMV-ADV sequential monotherapy. The rtA181V/T mutations were predominantly identified during the ADV treatment in the LMV-resistant patients. Twenty-seven of 38 clones were combined with an amino acid change at rt181; three clones had mutations in rt236 and one clone had a combined mutation. The rtA181V/T mutations were not suppressed by the LMV-ADV combination therapy. Thirty-nine of 64 clones showed an rtA181V/T mutation and six clones showed combined mutations in rt181 and rt236. Mutations in rt204 re-emerged during the combination treatment. The rt181 and rt204 mutations did not co-exist in one clone. CONCLUSION: Add-on lamivudine therapy with adefovir for adefovir resistance may not suppress the pre-existing adefovir-resistant mutation that develops during lamivudine-adefovir sequential monotherapy.
Silkworm Hemolymph Down-Regulates the Expression of Endoplasmic Reticulum Chaperones under Radiation-Irradiation
Kyeong Ryong Lee,Seung-Whan Kim,Young Kook Kim,Kisang Kwon,Jong-Soon Choi,Kweon Yu,O-Yu Kwon
International Journal of Molecular Sciences , 2011, DOI: 10.3390/ijms12074456
Abstract: We demonstrated that up-regulation of gene expression of endoplasmic reticulum (ER) chaperones (BiP, calnexin, calreticulin, ERp29) and ER membrane kinases (IRE1, PERK, ATF6) was induced by radiation in neuronal PC12 cells. However, addition of silkworm, Bombyx mori, hemolymph to irradiated cells resulted in an obvious decrease in expression of these genes, compared with a single radiation treatment. In contrast, one of the ER chaperones, “ischemia-responsive protein 94 kDa” (irp94), was up-regulated by radiation. However, addition of silkworm hemolymph resulted in no change in the expression of irp94, with an expression pattern that differed from that of ER chaperones. Based on these results, we propose that silkworm hemolymph contains factors that regulate a decrease in the expression of ER chaperones under radiation-irradiation conditions, with the exception of irp94, which is not down-regulated. We suggest that this difference in the molecular character of irp94 may provide a clue to the biological functions associated with ER stress pathways, particularly the effects of radiation.
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