Myungjoon Kim

Blockade of CD40–CD154 Costimulatory Pathway Promotes Long‐Term Survival of Full‐Thickness Porcine Corneal Grafts in Nonhuman Primates: Clinically Applicable Xenocorneal Transplantation

The porcine cornea may be a good solution for the shortage of human donor corneas because its size and refractive properties are comparable to those of the human cornea. However, antigenic differences need to be overcome to apply xenocorneal transplantation in actual clinical practice. We aimed to investigate the feasibility of full‐thickness porcine corneas as human corneal substitutes using a CD40–CD154 costimulatory pathway blocking strategy in a clinically applicable pig‐to‐nonhuman primate corneal transplantation model. As a result, the mean survival time of the xenocorneal grafts in recipients who received anti‐CD154 antibody‐based immunosuppressants (POD318 (n = 4); >933, >243, 318 and >192) was significantly longer than that in controls (POD28 (n = 3); 21, 28 and 29; p = 0.010, log‐rank test). Administration of anti‐CD154 antibodies markedly reduced inflammatory cellular infiltrations (predominantly CD8 T cells and macrophages) into the xenocorneal grafts and almost completely blocked xenoantigen‐triggered increases in Th1‐associated cytokines, chemokines and C3a in the aqueous humor. Moreover, systemic expansion of memory T cells was effectively controlled and responses of anti‐Gal/donor pig‐specific antibodies were considerably diminished by programmed injection of anti‐CD154 antibodies. Consequently, porcine corneas might be promising human corneal substitutes when the transplantation is accompanied by potent immunosuppression such as a CD40–CD154 costimulatory pathway blockade.

Short-time Fourier analysis via optimal harmonic FIR filters

The Fourier coefficients (FCs) of quasiperiodic signals are assumed to be in random walk motion in order to represent a broader class. A state model for such quasiperiodic signals is derived. The optimal short-time estimate of the Fourier coefficients is obtained via the suggested optimal harmonic FIR filter (OHFF) based on this state-space signal model. The optimal harmonic FIR filter can be considered to be a generalization of the discrete Fourier transform (DFT) in the sense that it becomes the same as the DFT when the state model is for periodic signals and the filter length is equal to the order of the state model. The optimal harmonic FIR filter derived from the model, even with nonzero state noise and measurement noise, gives an exact harmonic estimate when an incoming signal is periodic and noiseless. It is shown by examples that the ability to suppress noise and the ability to resolve changes of the Fourier coefficients can be adjusted by the filter length and the noise covariance of the state model. Finally, the suggested scheme is compared with existing short-time Fourier analysis methods in a test signal that has time-varying Fourier coefficients.

Receding Horizon Guidance Laws with No Information on the Time-to-Go

In this paper a modie ed optimal guidance law is proposed that does not use information on the time-to-go. The proposed receding horizon guidance law (RHG) is based on the receding horizon strategy and optimal control theory. In the presence of arbitrary target maneuvers and an initial lateral miss distance (MD) rate between the target and the missile, the proposed RHG is shown to guarantee to keep the lateral MD less than the given value, within which the warhead of the missile is detonated, from the appropriately selected time to the intercept time. Through threesimulation examples theability oftheRHGto interceptthetarget isillustrated. The performanceof theRHGiscompared with theoptimalguidancelawin termsoftheterminal MDwhen thetime-to-goisinaccurate, and in terms of the lateral MD and the missile acceleration when the time-to-go is accurate.

Modified receding horizon guidance law with information on small accurate time-to-go

A modified receding horizon guidance law (MRHG), which is useful when the accurate time-to-go is available only for a short time before the final time, is proposed. The proposed MRHG is based on the receding horizon strategy and optimal control theory. In the presence of arbitrary target maneuvers and an initial lateral miss distance (MD) rate between a target and a missile, it is shown that the proposed MRHG guarantees not only to keep the lateral MD less than a given value, within which the warhead of the missile is detonated, from the appropriately selected time to the intercept time, but also to render the terminal MD zero. Through simulations when the time-to-go is accurate only for a short time, the performance of MRHG is compared with the optimal guidance law (OGL) and the receding horizon guidance law (RHG) in terms of the terminal MD, the lateral MD, and the missile acceleration.

Susceptibility of Porcine Keratocytes to Immune-Mediated Damage in Xeno-Related Rejection

We admixed cultured porcine keratocytes or corneal endothelial cells in the presence of human sera or peripheral blood mononuclear cells (PBMCs) for 4 to 72 hours to investigate their immune-related susceptibilities to xeno-related rejection. We evaluated complement deposition at 48 hours by flow cytometry after staining with the C3 anti-goat cy3 antibody. The inhibition of proliferation of porcine corneal cells by human sera was examined using the 3-[4,5-dimethy/thiazol-2,5-dephenyl tetrazolium bromide (MTT) assay over 24 to 72 hours. The amount of 51chromium (Cr)-release was estimated after a reaction between the porcine cells and human PBMCs for 4 hours. There was greater C3 deposition in keratocytes (60.2%) than in endothelial cells (26.9%; P = .05, Mann-Whitney U test). Both keratocytes and endothelial cells showed significant levels of proliferative inhibition over a period of 72 hours. The number of 51Cr-release cells on interleukin-2 addition was significantly higher among keratocytes (88.0%) than endothelial cells (51.4%) at a 1:100 target:effector ratio (P = .04, Mann-Whitney U test). Our present data suggested that porcine keratocytes might be key target cells in xeno-related rejections when the porcine cornea is transplanted to primates.

Modern guidance laws via receding horizon control without the time-to-go

A receding horizon guidance law (RHG) is proposed which is useful when the time-to-go is inaccurate or is unavailable, or the accurate time-to-go is difficult to estimate in a sampling time. In the presence of arbitrary target maneuvers and an initial lateral miss distance rate between the target and missile, it is shown that the proposed RHG can make lateral miss distance (MD) below the predescribed value in the prespecified time without the time-to-go. Through simulation, guidance performance of RHG is illustrated and RHG is compared with the optimal guidance law in terms of miss distance and missile acceleration.

Generation of Humanized Liver Mouse Model by Transplant of Patient-Derived Fresh Human Hepatocytes

Some research groups have produced immunodeficient mice with human liver tissue as a model system for the analysis of drug metabolism and liver regeneration. Mouse models are important for research and development of drugs and vaccines for viral infections. Recent progress in developing humanized mouse models permits studies of adaptive immune responses, innate host responses, and therapeutic approaches for several liver diseases of viral etiology. In this study, we generated a humanized liver mouse model by transplant with fresh patient-derived hepatocytes (1 × 10(6) cells/mouse, intrasplenic injection) into preconditioned (50 mg/kg ganciclovir, intraperitoneal injection) mice (herpes simplex virus type 1 thymidine kinase [TK] transgene expressed within the liver of a highly immunodeficient mouse strain [NOG]). Successful reconstitution of human hepatocytes in TK-NOG mouse liver tissues was observed with a strong proliferation of human cells in a time-dependent manner, using cytokeratin 8/18 stain. Similarly, we detected significantly increased human albumin levels in TK-NOG mouse liver tissue and blood sera on immune staining and enzyme-linked immunosorbent assay. Therefore, this humanized liver mouse model provides a biomedical tool for studying human liver physiology, drug metabolism, and liver pathogenesis of viral etiology or liver regeneration.

Effects of Ceria Abrasive Particle Size Distribution below Wafer Surface on In-Wafer Uniformity during Chemical Mechanical Polishing Processing

In this study, the abrasive size distribution of ceria-based slurry below wafer and its effect on in-wafer uniformity were examined. Based on our observation, the abrasive size varies depending on the location on the wafer. Hence process parameters such as pad surface morphology and slurry viscosity were thoroughly investigated to observe their effect on the distribution on the wafer surface. It was found that the small size particles were considerably reduced near the center location of the wafer surface during the pad lifetime with reduced slurry viscosity and high polishing pressure. Hence, the contact conditions and the characteristic of fluid should be simultaneously considered in order to obtain the stable in-wafer uniformity.

Fabrication of three-dimensional scan-to-print ear model for microtia reconstruction

BACKGROUND Microtia is a congenital deformity of the external ear that occurs in 1 of every 5000 births. Microtia reconstruction using traditional two-dimensional templates does not provide highly detailed ear shapes. Here, we describe the feasibility of using a three-dimensional (3D) ear model as a reference. MATERIALS AND METHODS Seven children aged from 11 to 16 (6 grade III and 1 grade II microtia) were recruited from Seoul National University Childrens Hospital, Korea. We generated 3D-computer-aided design models of each patients ear by performing 3D laser scanning for a mirror-transformed cast of their normal ear. The 3D-printed ear model was used in microtia reconstruction surgery following the Nagata technique, and its shape was compared with the casted ear model. RESULTS One patient experienced irritation caused by accidently pouring resin into the external auditory meatus, and another had minor skin necrosis; both complications were successfully treated. The average percentage differences of the superior, inferior, anterior, posterior, and lateral views between the casted and 3D-printed ear models were 1.17%, 1.48%, 1.64%, 1.80%, and 5.44%, respectively (average: 2.31%), where the difference between the casted ear models and traditional two-dimensional templates were 16.03% in average. CONCLUSIONS Our results show that simple microtia reconstruction can be performed using 3D ear models. The 3D-printed ear models of each patient were consistent and accurately represented the thickness, depth, and height of the normal ear. The availability of the 3D-printed ear model in the operating room reduced the amount of unnecessary work during surgery.

Personal Cognitive Characteristics in Affordance Perception: The User Activity Case Study in a Building Lobby

User activities in performing tasks are influenced by the way the user perceives the related surrounding context and environment and determined with user judgment preferences. Physical environment structures afford user activities when these are perceived. Thus, this paper addresses how user activities and perceived affordances are different reflecting personal creativity modes, which are determined by factual-intuitive perception inclination and subjective-objective decision preferences as well as introverted-extroverted nature. To design-in various affordance features for diverse users in varying contexts, understanding on relations between user personal characteristics and affordance perception would be helpful. We conducted a case study in a public space — building lobby — used by many general people. User activities and behaviors were analyzed in several specific tasks given to twenty students in the lobby of a building they have never been to before. The tasks were devised so that various affordance features could be relevant while eliminating other factors affecting the affordance perception than those due to user personal characteristics. User activities can be classified into several different groups for each task based on affordance features involved in their activities. These user activity differences are then compared with their personal creativity modes. For user of less common activities for some tasks, relevant personal cognitive characteristics have been identified.Copyright