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Dive into the research topics where Chulho Oak is active.

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Featured researches published by Chulho Oak.


Respirology | 2011

Asbestos use and asbestos‐related diseases in Asia: Past, present and future

Giang Vinh Le; Ken Takahashi; Eun Kee Park; Vanya Delgermaa; Chulho Oak; Ahmad Munir Qureshi; Syed Mohamed Aljunid

Background and objective:  Although there are growing concerns about the global epidemic of asbestos‐related diseases (ARD), the current status of asbestos use and ARD in Asia is elusive. We conducted a descriptive analysis of available data on asbestos use and ARD to characterize the current situation in Asia.


Oncology Reports | 2013

Methylene blue-mediated photodynamic therapy enhances apoptosis in lung cancer cells.

Eun Jin Lim; Chulho Oak; Jeonghoon Heo; Young-Ho Kim

Combined treatment with a photosensitizer and iodide laser [photodynamic therapy (PDT)] has improved the outcome of various cancers. In this study, we investigated the effects of using the photosensitizer methylene blue (MB) in PDT in human lung adenocarcinoma cells. We found that MB enhances PDT-induced apoptosis in association with downregulation of anti-apoptotic proteins, reduced mitochondrial membrane potential (MMP), increased phosphorylation of the mitogen-activated protein kinase (MAPK) and the generation of reactive oxygen species (ROS). In MB-PDT-treated A549 cells, we observed PARP cleavage, procaspase-3 activation, downregulation of the anti-apoptotic proteins Bcl-2 and Mcl-1, and the reduction of mitochondrial membrane potential (MMP). Western blot data showed that phosphorylation of p38 was increased in MB-PDT-treated A549 cells, indicating that several signaling molecules participate in the apoptotic cascade. Our data also showed that apoptotic cell death in MB-PDT-treated cells occurred through a series of steps beginning with the photochemical generation of ROS. Demonstrating the role of ROS, pretreatment of A549 cells with the antioxidant N-acetylcysteine (NAC) followed by MB-PDT resulted in increased cell viability and reduced proteolytic cleavage of PARP.


International Journal of Pediatric Otorhinolaryngology | 2015

Rabbit model of tracheal stenosis induced by prolonged endotracheal intubation using a segmented tube

Hyoung Shin Lee; Sung Won Kim; Chulho Oak; Yeh-Chan Ahn; Hyun Wook Kang; Bong Kwon Chun; Kang Dae Lee

OBJECTIVE Animal model of tracheal stenosis based on pathophysiology of prolonged endotracheal intubation has been rarely reported. We sought to verify the feasibility of inducing an animal model of tracheal stenosis by segmented endotracheal tube insertion in the New Zealand white rabbit model. METHODS Tracheal stenosis was induced by inserting a segmented endotracheal tube of 1.5cm length which was wrapped with a commercialized absorbable hemostat in 15 New Zealand white rabbits, while sham surgery controls (n=3) underwent tracheotomy and direct closure of tracheal exposure. The tube was removed transorally, 1 week after tube insertion. All rabbits were evaluated endoscopically at 1 week, 2 weeks and 3 weeks after the tube insertion. The rabbits were sacrificed 3 weeks after the surgery, and the excised tissue of trachea was processed along with the procedure of standard hematoxylin eosin staining and observed under a microscope. RESULTS Tracheal stenosis was induced in all rabbits (range 32-84% stenosis) with no death of rabbits during the study. The histological features of tracheal stenosis demonstrated thickening and fibrosis of lamina propria and submucosa with relatively intact cartilage framework. CONCLUSIONS We developed a rabbit model of tracheal stenosis induced by endotracheal intubation using a segmented tracheal tube. Since the model is based on the physiologic condition of prolonged endotracheal intubation, it may be used in variable studies related to tracheal stenosis.


Safety and health at work | 2013

Awareness of Asbestos and Action Plans for Its Exposure can Help Lives Exposed to Asbestos

Hu-Jang Lee; Eun-Kee Park; Donald Wilson; Engin Tutkun; Chulho Oak

Despite the fact that asbestos is a known carcinogen to humans, it is still used in industrialized countries, especially Asian countries. The global incidence of asbestos-related diseases (ARDs) due to the past use of asbestos, continues to increase, although many countries have adopted a total ban on asbestos use. The implementation of effective strategies to eliminate ARDs is therefore an important challenge in Asia, where asbestos is still mined and consumed. Collaborative efforts and strategies at the local and international levels are vital, in the pursuit toward the elimination of ARDs in this region.


Lasers in Surgery and Medicine | 2015

Multimodal imaging using optical coherence tomography and endolaryngeal ultrasonography in a new rabbit VX2 laryngeal cancer model.

Chulho Oak; Yeh-Chan Ahn; Sung-Jin Nam; Maan Hong Jung; Sang Seok Hwang; Yu-Gyeong Chae; Hyoung Shin Lee; Kang Dae Lee; Min Jung Jung; Bong Kwon Chun; Hae Young Lee; Eun-Kee Park; Sung Won Kim

Optical coherence tomography (OCT) provides ultrahigh‐resolution imaging of tissues within a depth of a few millimeters, whereas ultrasonography provides good imaging further below the surface. We aimed to develop a minimally invasive rabbit model of VX2 laryngeal cancer, suitable for these two imaging modalities through a transoral approach. We also sought to study the utility of combined OCT and endolaryngeal ultrasonography (EUS) for evaluation of early and advanced laryngeal cancer, using this model.


Biomedical Optics Express | 2014

Optical imaging of subacute airway remodeling and adipose stem cell engraftment after airway injury

Yeh-Chan Ahn; Sung Won Kim; Sang Seok Hwang; Yu-Gyeong Chae; Andrew Sungwan Lee; Maan Hong Jung; Bong Kwon Chun; Sang Joon Lee; Eun-Kee Park; Chulho Oak

Acquired airway injury is frequently caused by endotracheal intubations, long-term tracheostomies, trauma, airway burns, and some systemic diseases. An effective and less invasive technique for both the early assessment and the early interventional treatment of acquired airway stenosis is therefore needed. Optical coherence tomography (OCT) has been proposed to have unique potential for early monitoring from the proliferative epithelium to the cartilage in acute airway injury. Additionally, stem cell therapy using adipose stem cells is being investigated as an option for early interventional treatment in airway and lung injury. Over the past decade, it has become possible to monitor the level of injury using OCT and to track the engraftment of stem cells using stem cell imaging in regenerative tissue. The purpose of this study was to assess the engraftment of exogenous adipose stem cells in injured tracheal epithelium with fluorescent microscopy and to detect and monitor the degree of airway injury in the same tracheal epithelium with OCT. OCT detected thickening of both the epithelium and basement membrane after tracheal scraping. The engraftment of adipose stem cells was successfully detected by fluorescent staining in the regenerative epithelium of injured tracheas. OCT has the potential to be a high-resolution imaging modality capable of detecting airway injury in combination with stem cell imaging in the same tracheal mucosa.


Lasers in Surgery and Medicine | 2017

Rabbit model of tracheal stenosis using cylindrical diffuser

Hyoung Shin Lee; Sung Won Kim; Chulho Oak; Hyun Wook Kang; Junghwan Oh; Min Jung Jung; Sung Bin Kim; Jun Hee Won; Kang Dae Lee

Variable methods of animal model have been introduced to develop tracheal stenosis. However, none of the prior models allow for predictable determination of the grade of stenosis. This study sought to establish an animal model of tracheal stenosis by using a cylindrical diffuser and to evaluate the feasibility of a reproducible model.


Lasers in Surgery and Medicine | 2016

Preliminary study of optical coherence tomography imaging to identify microscopic extrathyroidal extension in patients with papillary thyroid carcinoma.

Hyoung Shin Lee; Sung Won Shin; Jung Kweon Bae; Woong Gyu Jung; Sung Won Kim; Chulho Oak; Bong Kwon Chun; Yeh-Chan Ahn; Byung-Joo Lee; Kang Dae Lee

We evaluated the feasibility of using optical coherence tomography (OCT), to identify microscopic extrathyroidal extension (mETE) in ex vivo thyroidectomy specimens of patients who underwent thyroidectomy for the treatment of papillary thyroid carcinoma (PTC).


Journal of The Optical Society of Korea | 2015

In vivo Optical Coherence Tomography Imaging of the Mesothelium Using Developed Window Models

Yeh-Chan Ahn; Yu-Gyeong Chae; Sang Seok Hwang; Bong-Kwon Chun; Maan Hong Jung; Sung Jin Nam; Hae-Young Lee; Jae Min Chung; Chulho Oak; Eun-Kee Park

The mesothelium is an essential lining for maintaining the normal homeostasis of the closed body cavity and a central component of pathophysiologic processes. The mesothelium has been known as the end target for asbestos which induces asbestos-related lung diseases. Malignant mesothelioma (MM) is a rare and fatal neoplasm predominantly due to asbestos exposure. Adaptation of an advanced and reliable technology is necessary for early detection of MM because it is difficult to diagnose this disease in its early stages. Optical coherence tomography (OCT) provides cross-sectional images of micro-tissue structures with a resolution of


Journal of Photochemistry and Photobiology B-biology | 2015

The potential application of photodynamic therapy in drug-resistant tuberculosis

Ji-Eun Chang; Chulho Oak; Nackmoon Sung; Sanghoon Jheon

2-10{\mu}m

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Yeh-Chan Ahn

Pukyong National University

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Sang Seok Hwang

Pukyong National University

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Yu-Gyeong Chae

Pukyong National University

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