Kyung Mi Choi

A three dimensional adaptive finite element method for magnetostatic problems

A three dimensional adaptive finite element method for magnetostatic field problems is presented. Local errors are estimated from the discontinuity of the tangential components of the magnetic field intensity vector at the interfaces between elements in the finite element method, and mesh refinement is carried out by using a three-dimensional bisection method. The elements are refined according to the amount of error estimated. It is shown that the proposed method is easily used and acceptable for three-dimensional magnetostatic field problems. >

Calculation of small current breaking performance of gas circuit breaker considering the real gas properties of SF/sub 6/

The successful numerical analysis of breaking performance of gas circuit breaker (GCB) depends not only on the electric field analysis, but also on the properties of the insulating medium. SF/sub 6/ cannot be assumed to act as an ideal gas due to its imperfect thermodynamic properties. The cold flow simulation considering the real gas properties of SF/sub 6/ is presented in this paper and the dielectric breakdown of gas circuit breaker based on the simulation is also presented with the experimental data.

N-myc downstream-regulated gene 1 is involved in the regulation of cystogenesis in transgenic mice overexpressing human PKD2 gene.

Autosomal dominant polycystic kidney disease (ADPKD) is an inheritable and progressive kidney disease featured by the formation of fluid‐filled cysts. In a previous study, transgenic mice overexpressing human PKD2 gene were produced as an ADPKD animal model. To select genes controlled by PKD2, 2DE was performed using kidney tissues of 12‐ and 18‐month‐old transgenic mice. The protein localization was detected by immunohistochemistry, and 3D culture was utilized to observe in vitro cystogenesis. As a result, N‐myc downstream‐regulated gene 1 (NDRG1) was chosen as a candidate regulator gene of cystogenesis. NDRG1 is an intracellular protein involved in cellular proliferation and differentiation. This gene was expressed much higher in the kidney of hPKD2 TG mice. Also, the high level of NDRG1 protein was detected in the cyst lining epithelial cells. The hypothesis that PKD2 gene regulates NDRG1 expression was supported, and NDRG1 knockdown resulted in attenuation of cyst growth in vitro. Furthermore, NDRG1 knockdown suppressed cellular growth in mouse inner medullary collecting duct‐3 cells. We found that early growth response 1, a transcription factor that binds to the NDRG1 promoter, was mediated in the NDRG1 expression regulation by PKD2. In this study, we found the novel gene that was involved in cystogenesis, which will provide the new insight in ADPKD.

Proteomic analysis of kidneys from selenoprotein M transgenic rats in response to increased bioability of selenium

BackgroundTo characterize changes in global protein expression in kidneys of transgenic rats overexpressing human selenoprotein M (SelM) in response to increased bioabivility of selenium (Sel), total proteins extracted from kidneys of 10-week-old CMV/hSelM Tg and wild-type rats were separated by 2-dimensional gel electrophoresis and measured for changes in expression.ResultsTen and three proteins showing high antioxidant enzymatic activity were up- and down-regulated, respectively, in SelM-overexpressing CMV/hSelM Tg rats compared to controls based on an arbitrary 2-fold difference. Up-regulated proteins included LAP3, BAIAP2L1, CRP2, CD73 antigen, PDGF D, KIAA143 homolog, PRPPS-AP2, ZFP313, HSP-60, and N-WASP, whereas down-regulated proteins included ALKDH3, rMCP-3, and STC-1. After Sel treatment, five of the up-regulated proteins were significantly increased in expression in wild-type rats, whereas there were no changes in CMV/hSelM Tg rats. Only two of the down-regulated proteins showed reduced expression in wild-type and Tg rats after Sel treatment.ConclusionsThese results show the primary novel biological evidences that new functional protein groups and individual proteins in kidneys of Tg rats relate to Sel biology including the response to Sel treatment and SelM expression.

Generation of Non-uniform Meshes for Finite-Difference Time-Domain Simulations

In this paper, an automatic mesh generation algorithm is presented. The method seeks to optimize mesh density with regard to geometries exhibiting both fine and coarse physical structures. Additionally, when generating the mesh, the algorithm attempts to simultaneously satisfy the limiting conditions of maximum mesh spacing and maximum grading ratio

Clusterin is highly expressed in tubular complexes during spontaneous pancreatitis of spontaneous hypertensive rats

Pancreatitis is an inflammatory disorder of pancreas which leads to varying degrees of pancreatic endocrine and exocrine dysfunction and manifests in either acute or chronic forms. Spontaneous pancreatitis in experimental animals has rarely been reported. Here, we found acute to chronic courses of spontaneous pancreatitis in spontaneously hypertensive rats (SHRs), showing the formation of tubular complexes (TCs) and enhanced islet regeneration. We investigated the expression pattern of clusterin in the pancreas of SHRs based on immunohistochemistry (IHC). IHC analysis revealed the strong expression of clusterin in dedifferentiated duct-like cells and regenerative islets of TCs. These results imply that clusterin might be involved in the formation of TCs and parenchymal regeneration during rat pancreatitis.