Publications by authors named "Yong Woo Chung"

While a clear operating field during endoscopy is essential for accurate diagnosis and effective surgery, fogging or biofouling of the lens can cause loss of visibility during these procedures. Conventional cleaning methods such as the use of an irrigation unit, anti-fogging surfactant, or particle-based porous coatings infused with lubricants have been used but proven insufficient to prevent loss of visibility. Herein, a mechanically robust anti-fogging and anti-biofouling endoscope lens was developed by forming a lubricant-infused directly engraved nano-/micro-structured surface (LIDENS) on the lens.

View Article and Find Full Text PDF

Biological responses on biomaterials occur either on their surface or at the interface. Therefore, surface characterization is an essential step in the fabrication of ideal biomaterials for achieving effective control of the interaction between the material surface and the biological environment. Herein, we applied femtosecond laser ablation on electrospun fibrous scaffolds to fabricate various hierarchical patterns with a focus on the alignment of cells.

View Article and Find Full Text PDF

A monolayer of endothelial cells (ECs) aligned along the direction of blood flow plays crucial roles in the regulation of anti-thrombogenic and pro-inflammatory reactions in the blood vessel wall. Thus, many researchers have attempted to mimic the aligned structure of ECs in vascular grafts or tissue-engineered blood vessels. In the present study, we fabricated micro-groove patterned nanofibers using a femtosecond laser ablation technique to recapitulate the densely organized anisotropic architecture of the endothelial layer.

View Article and Find Full Text PDF

Implanted material surfaces make direct contact with body tissues to work on its own purpose. Therefore, studies of the surface properties of implantable materials that determine cell fate are very important for successful implantation. Although numerous studies have addressed the relationship between cells and material surfaces, nonmetallic surfaces and metallic surfaces likely produce different cellular responses because of their intrinsic differences in surface energy, roughness, and chemical composition.

View Article and Find Full Text PDF

Developing an artificial extracellular matrix that closely mimics the native tissue microenvironment is important for use as both a cell culture platform for controlling cell fate and an in vitro model system for investigating the role of the cellular microenvironment. Electrospinning, one of the methods for fabricating structures that mimic the native ECM, is a promising technique for creating fibrous platforms. It is well-known that align or randomly distributed electrospun fibers provide cellular contact guidance in a single pattern.

View Article and Find Full Text PDF

Background/aims: Microscopic colitis (MC) encompasses collagenous and lymphocytic colitis and is characterized by chronic diarrhea. In cases of MC, colonic mucosae are macroscopically normal, and diagnostic histopathological features are observed only upon microscopic examination. We designed a prospective multicenter study to determine the clinical features, pathological distribution in the colon and prevalence of MC in Korea.

View Article and Find Full Text PDF

Background: Inadequate bowel preparation is important because it can result in missed lesions, cancelled procedures, increased procedural time, and a potential increase in complication rates. This prospective study was designed to look at the quality of colon preparation using polyethylene glycol solution and evaluate potential associations between specific patient characteristics and inadequate bowel preparation.

Methods: A total of 362 patients who were compliant with preparation instructions were enrolled.

View Article and Find Full Text PDF

Foreign bodies in the colon are encountered with increasing frequency, but only sporadic reports concerning their management have appeared in the literature. While most ingested foreign bodies usually pass through the gastrointestinal tract uneventfully, sharp foreign bodies such as toothpicks infrequently cause intestinal perforation and may even result in death. We report our experience with a patient with a sigmoid colon pseudodiverticulum formation, a complication of accidental ingestion of a toothpick that was diagnosed and successfully managed colonoscopically.

View Article and Find Full Text PDF

Purpose: Patients with Type 2 diabetes mellitus may be at increased colorectal adenoma and cancer risk. Moreover, chronic insulin therapy may increase the risk of colorectal cancer among patients with Type 2 diabetes mellitus. We investigated to determine whether insulin therapy might increase the risk of colorectal adenoma among clinically confirmed patients with Type 2 diabetes mellitus.

View Article and Find Full Text PDF

Groove pancreatitis is a rare form of chronic pancreatitis in which scarring is found mainly in the groove between the head of the pancreas, duodenum, and common bile duct. The pathogenesis of groove pancreatitis is still unclear but seems to be caused by the disturbance of pancreatic outflow through Santorini duct. It is often difficult to differentiate preoperatively between groove pancreatitis and pancreatic head carcinoma.

View Article and Find Full Text PDF

Background: The incidence of H. pylori-negative, idiopathic peptic ulcer disease (IPUD) seems to be increasing with the changing trends of PUD and H. pylori infection in some developed countries.

View Article and Find Full Text PDF

Lymphangiomas are rare, benign tumors of the lymphatic system, usually present in children aged 5 years and younger. Because they are asymptomatic until the mass enlarges to cause symptoms, most lymphangiomas are diagnosed at adulthood incidentally. We experienced a case of a 60-year-old man diagnosed with a cystic lymphangioma of the gallbladder, which was successfully resected without any complication.

View Article and Find Full Text PDF

Colorectal cancer is one of the leading causes of cancer death in the United States and Europe. Recently, the incidence of colorectal cancer has been increasing remarkably in Korea. To reduce the high incidence, screening of colorectal cancer in asymptomatic individuals has been advocated.

View Article and Find Full Text PDF

The Mucosa-associated lymphoid tissue (MALT) lymphoma, which was first described in 1983, is known to be caused by chronic Helicobacter pylori (HP) infection, which triggers lymphoid infiltration and formation of organized lymphoid tissue. In approximately two thirds of cases of MALT, the lymphoma has been observed to regress after treatment of H. pylori infection; this provides strong evidence of a causative role of HP in the etiology of MALT.

View Article and Find Full Text PDF

CyberKnife is an image-guided robotic system designed for stereotactic radiosurgery. It uses the combination of robotics and image guidance to deliver concentrated and accurate beams of radiation to intracranial and extracranial targets. Although the frameless nature of the CyberKnife allows tumors in the chest and abdomen to be treated as well, complications associated with CyberKnife treatment have not been established yet due to its short clinical experience.

View Article and Find Full Text PDF

The peroxisome proliferator-activated receptor gamma (PPARgamma) is a nuclear receptor highly expressed in the colon and playing an anti-inflammatory role through inhibition of the NF-kappaB pathway. Toll-like receptor 4 (TLR4) has been known to mediate LPS-induced cellular signaling through activation of NF-kappaB pathway in intestinal epithelial cells. The aims of this study were to evaluate attenuation of inflammation by PPARgamma in intestinal epithelial cells and to study the possible relation between PPARgamma and TLR4.

View Article and Find Full Text PDF

Macroenzymes are normal enzymes complexed with an immunoglobulin (usually IgG, rarely IgA or IgM). A number of macroenzymes have been reported in the literature. Among them, macro-AST has been detected in diseases such as acute and chronic hepatitis, various malignancies and autoimmune diseases, but usually not associated with any specific disease.

View Article and Find Full Text PDF

Percutaneous liver biopsy is well established for the diagnosis and follow-up of many liver diseases. Although it is rather safe, major complications, such as bleeding into the peritoneal or thoracic cavity, hemobilia, enteric perforation and intrahepatic hematoma, have been reported related to the procedure. Recently, incidence of such major complications has been decreased since the introduction of ultrasonography-guided liver biopsy.

View Article and Find Full Text PDF

Background/aims: The number of patients with ulcerative colitis has steadily increased since the mid-1980s. As the risk of colon cancer increases with duration and extents, colitic cancers are expected to increase in number in Korea. We surveyed the current status of colitic cancers and provided the perspectives in Korea.

View Article and Find Full Text PDF

Xanthogranulomatous inflammation (XGI) is a well-recognized disease process in the kidney and gallbladder. However, involvement of the colon is extremely rare. On the other hand, it is important to recognize that clinically and radiologically, XGI could be misinterpreted as an infiltrative cancer.

View Article and Find Full Text PDF