Pusan National University

About: Pusan National University is a education organization based out in Busan, South Korea. It is known for research contribution in the topics: Population & Catalysis. The organization has 24124 authors who have published 45054 publications receiving 819356 citations. The organization is also known as: Busan National University & Pusan University.

The wound healing response after laser in situ keratomileusis and photorefractive keratectomy: elusive control of biological variability and effect on custom laser vision correction.

Abstract: Biological diversity in the wound healing response is thought to be a major factor limiting the predictability of the outcome of refractive surgical procedures such as laser in situ keratomileusis and photorefractive keratectomy. Corneal wound healing is critical to the success of topography-linked or wave front-linked excimer laser ablation to optimize visual performance. This is because of the importance of retaining subtle features of custom ablation and the tendency of epithelial hyperplasia and stromal remodeling to obscure these features following either procedure. The corneal wound healing response is exceedingly complex. Keratocyte apoptosis, which occurs in response to epithelial injury, is the earliest observable event in the wound healing cascades and is therefore an excellent target for pharmacological intervention. Alterations of surgical technique can be designed to limit keratocyte apoptosis and the subsequent events in corneal wound healing. Abnormalities of the cascades could contribute to the pathogenesis of corneal diseases. For example, recent data have suggested that perturbation of the keratocyte apoptosis/mitosis balance could underlie the development of keratoconus in a proportion of patients.

Role of Oncogenic K-Ras in Cancer Stem Cell Activation by Aberrant Wnt/β-Catenin Signaling

Abstract: BACKGROUND Adenomatous polyposis coli (APC) loss-of-function mutations and K-Ras gain-of-function mutations are common abnormalities that occur during the initiation and intermediate adenoma stages of colorectal tumorigenesis, respectively. However, little is known about the role these mutations play in cancer stem cells (CSCs) associated with colorectal cancer (CRC) tumorigenesis. METHODS We analyzed tissue from CRC patients (n = 49) to determine whether K-Ras mutations contributed to CSC activation during colorectal tumorigenesis. DLD-1-K-Ras-WT and DLD-1-K-Ras-MT cells were cultured and evaluated for their ability to differentiate, form spheroids in vitro, and form tumors in vivo. Interaction between APC and K-Ras mutations in colorectal tumorigenesis was evaluated using APC (Min/+)/K-Ras (LA2) mice and DLD-1-K-Ras-WT and DLD-1-K-Ras-MT cell xenografts. (n = 4) Group differences were determined by Student t test. All statistical tests were two-sided. RESULTS The sphere-forming capability of DLD-1-K-Ras-MT cells was statistically significantly higher than that of DLD-1-K-Ras-WT cells (DLD-1-K-Ras-MT mean = 86.661 pixel, 95% confidence interval [CI] = 81.701 to 91.621 pixel; DLD-1-K-Ras-WT mean = 42.367 pixel, 95% CI = 36.467 to 48.267 pixel; P = .003). Moreover, both the size and weight of tumors from DLD-1-K-Ras-MT xenografts were markedly increased compared with tumors from DLD-1-K-Ras-WT cells. Expression of the CSC markers CD44, CD133, and CD166 was induced in intestinal tumors from APC (Min/+)/K-Ras (LA2)mice, but not K-Ras (LA2) mice, indicating that APC mutation is required for CSC activation by oncogenic K-Ras mutation. CONCLUSIONS K-Ras mutation activates CSCs, contributing to colorectal tumorigenesis and metastasis in CRC cells harboring APC mutations. Initial activation of β-catenin by APC loss and further enhancement through K-Ras mutation induces CD44, CD133, and CD166 expression.

Clustering of peptidoglycan recognition protein-SA is required for sensing lysine-type peptidoglycan in insects.

Abstract: Recognition of lysine-type peptidoglycan by peptidoglycan recognition protein (PGRP)-SA provokes the activation of the Toll and prophenoloxidase pathways. Here we reveal that a soluble fragment of lysine-type peptidoglycan, a long glycan chain with short stem peptides, is a potent activator of the Drosophila Toll pathway and the prophenoloxidase activation cascade in the beetle Tenebrio molitor. Using this peptidoglycan fragment, we present biochemical evidence that clustering of PGRP-SA molecules on the peptidoglycan is required for the activation of the prophenoloxidase cascade. We subsequently highlight that the lysozyme-mediated partial digestion of highly cross-linked lysine-type peptidoglycan dramatically increases the binding of PGRP-SA, presumably by inducing clustering of PGRP-SA, which then recruits the Gram-negative bacteria-binding protein 1 homologue and a modular serine protease containing low-density lipoprotein and complement control protein domains. The crucial role of lysozyme in the prophenoloxidase activation cascade is further confirmed in vivo by using a lysozyme inhibitor. Taken together, we propose a model whereby lysozyme presents a processed form of lysine-type peptidoglycan for clustering of PGRP-SA that recruits Gram-negative bacteria-binding protein 1 and the modular serine protease, which leads to the activation of both the Toll and prophenoloxidase pathways.