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Search Results: 1 - 10 of 13730 matches for " Young-Sam Choi "
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Cornual patency and integrity following laparoscopic cornuotomy for interstitial pregnancy  [PDF]
Young-Sam Choi, Dae-Sook Eun, Yun-Sang Oh, Ji-No Park
Open Journal of Obstetrics and Gynecology (OJOG) , 2012, DOI: 10.4236/ojog.2012.22024
Abstract: Objective: To evaluate cornual patency and integrity following laparoscopic cornuotomy. Study Design: This is a prospective cohort study on seven women who underwent laparoscopic cornuotomy for interstitial pregnancy. The cornual patency and integrity were evaluated using hysterosalpingography (HSG) and magnetic resonance imaging (MRI). On MRI, the entire cornual wall thickness were measured bilaterally at 5-mm intervals. The thickness of the affected and unaffected cornua matched at the corresponding contralateral point in each of the women. Statistically, all possible pairwise 28 comparisons were compared using paired t-tests. Results: Among six eligible women, four women had excellent cornual patency on the affected side. Among seven women (i.e., 28 pairs), no significant difference was observed in cornual thickness compared to the unaffected cornu and no remarkable defects were seen in the endometrial and cornual contour. But there is no statistical significance. Conclusion: Laparoscopic cornuotomy seems to have advantage to preserve the cornu in interstitial pregnancy.
On the Incompressible Limit for the Compressible Flows of Liquid Crystals under Strong Stratification on Bounded Domains
Young-Sam Kwon
Abstract and Applied Analysis , 2013, DOI: 10.1155/2013/253260
Single-Port Access Laparoscopy-Assisted Vaginal Hysterectomy: Our Initial Experiences with 100 Cases
Young-Sam Choi,Kwang-Sik Shin,Jin Choi,Ji-No Park,Yun-Sang Oh,Tae-Eel Rhee
Minimally Invasive Surgery , 2012, DOI: 10.1155/2012/543627
Abstract: Objectives. To present our initial experiences with laparoscopically assisted vaginal hysterectomy performed using homemade transumbilical single-port system. Materials and Methods. We reviewed the medical records of one hundred patients who underwent single-port access laparoscopically assisted vaginal hysterectomy (SPA-LAVH). SPA-LAVH was performed with homemade single port system and conventional rigid laparoscopic instruments. Results. All procedures were successfully completed through the single-port system and vagina without need for extraumbilical puncture or conversion to laparotomy. The median patient age was 48.2 ± 6.5 years. Thirty-three patients had history of past abdominopelvic surgery. The median total operative time, largest dimension of the uterus, and weight of the uterus were 73.1 ± 24.6?min, 10.5 ± 2.1?cm, and 300.8 ± 192.5?gram, respectively. The median decline in the hemoglobin from before surgery to postoperative day 1 was 1.8 ± 0.9?g/dL. Bladder injury in occurred one patient who was repaired through intraoperative laparoscopic suture. The postoperative course was uneventful in most patients except for three who had a transient paralytic ileus, five who had pelvic hematoma, but they were recovered following conservative managements. No port-related complications were noted, and the cosmetic results were excellent. Conclusions. SPA-LAVH is technically safe procedure, and the homemade single-port system offers reliable access for single-port surgery. 1. Introduction To optimize the benefits of minimally invasive procedures, surgeons have attempted to reduce the overall abdominal wall trauma by decreasing either the size of the ports or the number of trocars. In these efforts, transumbilical single-port surgery uses an umbilical single incision technique to access the peritoneal cavity and target organs. Owing to the nature of umbilicus, single-port laparoscopy through the umbilicus offers an exciting opportunity to perform laparoscopic surgery with no visible scar. However, transumbilical single-port laparoscopy is not a new concept in gynecologic surgery [1–5]. In 1969, Wheeless and Thompson first published the technique and the results of a large series of laparoscopic tubal ligations using single-trocar laparoscopy. Later, Wheeless reported a large series of one-incision tubal ligation. Additionally, in 1991, the first laparoscopic total abdominal hysterectomy with bilateral salpingooophorectomy (BSO) using only a single incision was reported by Pelosi and Pelosi III. One year later, four supracervical hysterectomies with BSO
Keap1 Cysteine 288 as a Potential Target for Diallyl Trisulfide-Induced Nrf2 Activation
Sanghyun Kim, Hee-Geum Lee, Sin-Aye Park, Joydeb Kumar Kundu, Young-Sam Keum, Young-Nam Cha, Hye-Kyung Na, Young-Joon Surh
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0085984
Abstract: Diallyl sulfide, diallyl disulfide, and daillyl trisulfide (DATS) are major volatile components of garlic oil. In this study, we assessed their relative potency in inducing antioxidant enzyme expression. Among the three organosulfur compounds, DATS was found to be most potent in inducing heme oxygenase-1 (HO-1) and NAD(P)H:quinone oxidoreductase-1 (NQO1) in human gastric epithelial (AGS) cells. Furthermore, DATS administration by gavage increased the expression of HO-1 and NQO1 in C57BL/6 mouse stomach. Treatment with DATS increased the accumulation of nuclear factor-erythroid-2-related factor-2 (Nrf2) in the nucleus of cultured AGS cells and in mouse stomach in vivo. The DATS-induced expression of HO-1 and NQO1 was abrogated in the cells transiently transfected with Nrf2-siRNA or in the embryonic fibroblasts from Nrf2-null mice, indicating that Nrf2 is a key mediator of the cytoprotective effects of DATS. Pretreatment of AGS cells with N-acetylcysteine or dithiothreitol attenuated DATS-induced nuclear localization of Nrf2 and the expression of HO-1 and NQO1. Cysteine-151, -273 and -288 of Kelch-like ECH-associated protein-1 (Keap1), a cytosolic repressor of Nrf2, have been considered to act as a redox sensor and play a role in Nrf2 activation. To determine whether DATS could inactivate Keap1 through thiol modification, we established cell lines constitutively expressing wild type-Keap1 or three different mutant constructs in which cysteine-151, -273, or -288 of Keap1 was replaced with serine by retroviral gene transfer. DATS failed to activate Nrf2, and to induce expression of HO-1 and NQO1 only in Keap1-C288S mutant cells. LC-ESI-MS/MS analysis of recombinant Keap1 treated with DATS revealed that the peptide fragment containing Cys288 gained a molecular mass of 72.1 Da equivalent to the molecular weight of mono-allyl mono-sulfide. Taken together, these findings suggest that DATS may directly interact with the Cys288 residue of Keap1, which partly accounts for its ability to induce Nrf2 activation and upregulate defensive gene expression.
Eyelid Squamous Cell Carcinoma in a Dog
Chang-hyun Song1§, Sae-kwang Ku2§, Hwan-soo Jang3, Eun-young Kye, Sung-ho Yun, Kwang-ho Jang and Young-sam Kwon*
Pakistan Veterinary Journal , 2012,
Abstract: A 10-year-old, female, Yorkshire Terrier was presented with a left lower eyelid mass. No other abnormality was detected on affected eye in a general eye examination. The mass was surgically removed and histologically diagnosed as a squamous cell carcinoma. The advancement flap used in this case may be an appropriate therapeutic choice for eyelid squamous cell carcinoma in dogs.
Analogous Mechanisms of Resistance to Benzothiazinones and Dinitrobenzamides in Mycobacterium smegmatis
Ana Luisa de Jesus Lopes Ribeiro, Giulia Degiacomi, Fanny Ewann, Silvia Buroni, Maria Loreto Incandela, Laurent R. Chiarelli, Giorgia Mori, Jaeseung Kim, Monica Contreras-Dominguez, Young-Sam Park, Sung-Jun Han, Priscille Brodin, Giovanna Valentini, Menico Rizzi, Giovanna Riccardi, Maria Rosalia Pasca
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0026675
Abstract: Tuberculosis is still a leading cause of death worldwide. The selection and spread of Mycobacterium tuberculosis multidrug-resistant (MDR-TB) and extensively drug-resistant strains (XDR-TB) is a severe public health problem. Recently, two different classes of chemical series, the benzothiazinones (BTZ) and the dinitrobenzamide (DNB) derivatives have been found to be highly active against M. tuberculosis, including XDR-TB strains. The target of BTZs is DprE1 protein which works in concert with DprE2 to form the heteromeric decaprenylphosphoryl-β-D-ribose 2′-epimerase, involved in Decaprenyl-Phospho-Arabinose (DPA) biosynthesis. Interestingly, it has been shown that the DNBs block the same pathway thus suggesting that both drugs could share the same target. Moreover, in Mycobacterium smegmatis the overexpression of the NfnB nitroreductase led to the inactivation of the BTZs by reduction of a critical nitro-group to an amino-group. In this work several spontaneous M. smegmatis mutants resistant to DNBs were isolated. Sixteen mutants, showing high levels of DNB resistance, exhibited a mutation in the Cys394 of DprE1. Using fluorescence titration and mass spectrometry it has been possible to monitor the binding between DprE1 and DNBs, achieving direct evidence that MSMEG_6382 is the cellular target of DNBs in mycobacteria. Additionally, M. smegmatis mutants having low levels of resistance to DNBs harbor various mutations in MSMEG_6503 gene encoding the transcriptional repressor of the nitroreductase NfnB. By LC/MS2 analysis it has been demonstrated that NfnB is responsible for DNB inactivation. Taken together, our data demonstrate that both DNB and BTZ drugs share common resistance mechanisms in M. smegmatis.
Spin Operators for Massive Particles
Taeseung Choi,Sam Young Cho
Physics , 2014,
Abstract: How to define a proper relativistic spin operator, as a long-standing problem, has by now become a central task for providing proper concepts and applications of spin in relativistic and non-relativistic quantum mechanics as well as solving emergent inconsistencies in rapidly developing research areas. We rigorously {\it derive} a relativistic spin operator for an arbitrary spin massive particle on the two requirements that a proper spin operator should satisfy (i) the $\mathfrak{su}(2)$ algebra and (ii) the Lorentz-transformation properties as a second-rank spin tensor. These requirements lead to two spin operators, properly giving the second Casimir invariant operator in the Poincar\'e (inhomogeneous Lorentz) group, that provide the two inequivalent representations of Poincar\'e group. We find that the two inequivalent representations are the left-handed and the right-handed representations. Each of the two spin operators generates a Wigner little group whose representation space is composed of spin-$s$ spin states. In the case that the Poincar\'e group is extended by parity, only nonchiral $(s,s)$ representations and direct-sum $(s,s') \oplus (s',s)$ representations are allowed. In the $(1/2,0)\oplus (0,1/2)$ representation, we redrive the covariant Dirac equation by using the covariant parity operator defined by the two spin operators. This derivation deepens our understanding how the Dirac equation describes the spin-$1/2$ massive relativistic particle successfully. We have also discussed some important properties of our relativistic spin operators with arbitrary spin.
Comment on "Aharonov-Casher and Scalar Aharonov-Bohm Topological Effects"
Taeseung Choi,Sam Young Cho
Physics , 2013, DOI: 10.1103/PhysRevLett.112.158901
Abstract: In this Comment we point out (i) that the Hamiltonian, Eq. (17) in the Letter(Phys. Rev. Lett. 108, 070405 (2012)), is not a relativistic Hamiltonian, (ii) then that the conditions in the Letter are irrelevant for a topological AC and SAB effects, and (iii) conclusively that the non-relativistic Hamiltonian employed by Peshkin and Lipkin (Phys. Rev. Lett. 74, 2847 (1995)) has the same $U(1)_{mm}$ gauge structure for a fixed spin and then is not wrong, but their incorrect interpretation of the spin autocorrelations led to the incorrect conclusion.
Entanglement and Berry Phase in Two Interacting Qubits
Ai Min Chen,Sam Young Cho,Taeseung Choi
Physics , 2008,
Abstract: Entanglement and Berry phase are investigated in two interacting qubit systems. The XXZ spin interaction model with a slowly rotating magnetic field is employed for the interaction between the two qubits. We show how the anisotropy of interaction reveals unique relations between the Berry phases and the entanglements for the eigenstates of the system.
A Comparison Study of Input ESD Protection Schemes Utilizing NMOS, Thyristor, and Diode Devices  [PDF]
Jin Young Choi
Communications and Network (CN) , 2010, DOI: 10.4236/cn.2010.21002
Abstract: For three fundamental input-protection schemes suitable for high-frequency CMOS ICs, which utilize protection devices such as NMOS transistors, thyristors, and diodes, we attempt an in-depth comparison on HBM ESD robustness in terms of lattice heating inside protection devices and peak voltages developed across gate oxides in input buffers, based on DC, mixed-mode transient, and AC analyses utilizing a 2-dimensional device simulator. For this purpose, we construct an equivalent circuit model of input HBM test environments for CMOS chips equipped with input ESD protection circuits, which allows mixed-mode transient simulations for various HBM test modes. By executing mixed-mode simulations including up to six active protection devices in a circuit, we attempt a detailed analysis on the problems, which can occur in real tests. In the procedure, we suggest to a recipe to ease the bipolar trigger in the protection devices and figure out that oxide failure in internal circuits is determined by the peak voltage developed in the later stage of discharge, which corresponds to the junction breakdown voltage of the NMOS structure residing in the protection devices. We explain strength and weakness of each protection scheme as an input ESD protection circuit for high-frequency ICs, and suggest valuable guidelines relating design of the protection devices and circuits.
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