Soon Man Yoon

Polymeric Nanoparticle-Based Activatable Near-Infrared Nanosensor for Protease Determination In Vivo

We report here a new protease activatable strategy based on a polymer nanoparticle platform. This nanosensor delivers chemically labeled matrix metalloproteinase (MMP)-activatable fluorogenic peptides to the specific MMPs of interest in vivo. Intravenous administration of the nanosensor in an MMP-positive SCC-7 xenograft tumor and a colon cancer mouse model verified the enzyme specificity of the nanosensor in vivo. The design platform of the nanosensor is flexible and can be fine-tuned for a wide array of applications such as the detection of biomarkers, early diagnosis of disease, and monitoring therapeutic efficacy.

Endoscopic submucosal dissection for treatment of rectal carcinoid tumors

BACKGROUND Conventional EMR has been the endoscopic treatment of choice for rectal carcinoid tumors. However, histologically complete resection often cannot be achieved because the carcinoid tumors are located mainly in the submucosal layer. Endoscopic submucosal dissection (ESD), a new method for large colorectal neoplasm resection, may overcome this problem. OBJECTIVE To compare ESD with EMR for the endoscopic treatment of rectal carcinoid tumors. DESIGN A prospective case series with comparison to retrospective controls. SETTING Tertiary-care center. PATIENTS From January 2007 to January 2009 we prospectively enrolled consecutive patients with rectal carcinoid tumors less than 16 mm in diameter and with no regional lymph node enlargement shown by CT or EUS. For comparison, we retrospectively randomly selected patients who had undergone EMR for treatment of rectal carcinoid tumors between March 2000 and December 2006. INTERVENTION We performed ESD of rectal carcinoid tumors in prospectively enrolled patients. MAIN OUTCOME MEASUREMENTS Rate of en bloc resection, rate of histologically complete resection, incidence of complications, and length of procedures. RESULTS The ESD group contained 31 patients (18 male, 13 female; age range 34-65 years), and the EMR group contained 62 patients (42 male, 20 female; age range 22-77 years). Both groups had similar mean rectal carcinoid tumor diameters (ESD 6.8 +/- 2.4 mm, EMR 7.3 +/- 2.2 mm; P = .106). Resection time was longer in the ESD group than in the EMR group (11.4 +/- 3.7 minutes vs 4.2 +/- 3.2 minutes, P < .001). The en bloc resection rate was 100% (31 of 31) in the ESD group and 95.2% (59 of 62) in the EMR group (P = .213). The histologically complete resection rate was 90.3% (28 of 31) in the ESD group and 71.0% (44 of 62) in the EMR group (P = .035). Suspected perforation occurred in 1 ESD patient (3.2%) and in 1 EMR patient (1.6%), and both patients were successfully managed by conservative measures. Immediate bleeding occurred in 1 ESD patient (3.2%) and in 4 EMR patients (6.5%); all instances of bleeding were controlled endoscopically. LIMITATIONS Retrospective control study and limited experience at a single center. CONCLUSION Compared with EMR, ESD resulted in a higher histologically complete resection rate, had a similar complication rate, and took slightly longer to perform. Given the advantages of complete resection, these findings indicate that ESD may be considered for treatment of rectal carcinoid tumors.

Clinical features and long-term prognosis of Crohn's disease in Korea

Abstract Objective. Recent studies have suggested that the clinical characteristics and genetic background of Crohns disease (CD) patients differ between Asian and Caucasian individuals. However, the clinical features and course of CD in Asian patients remain unclear. Therefore, we investigated the clinical features and long-term prognosis of CD in a Korean population. Material and methods. We retrospectively analyzed 278 Korean patients with CD first diagnosed at the Asan Medical Center between March 1991 and February 2007. Results. The male-to-female ratio was 2.2:1 and the median age at diagnosis was 23 years. The median duration of follow-up was 71 months (range, 1–210 months). At diagnosis, 187 patients (67.3%) had disease in both small bowel and colon, 68 (24.4%) had isolated small bowel disease, and 23 (8.3%) had isolated colonic disease. The number of patients with stricturing or penetrating behavior as defined by the Montreal classification increased from 87 (31.3%) at diagnosis to 141 (50.7%) at final evaluation. One hundred and thirty patients (46.8%) experienced perianal fistulas before and/or after diagnosis of CD. A total of 71 patients (25.5%) underwent intestinal resection and the cumulative probability of intestinal resection after 1, 5, and 10 years was 15.5%, 25.0%, and 32.8%, respectively. Conclusions. Korean CD patients differed from Western patients in gender distribution, disease location, and perianal fistula occurrence. Korean CD patients may also have better clinical courses than Western patients, as indicated by the lower intestinal resection rate.

Clinical characteristics of ulcerative colitis associated with primary sclerosing cholangitis in Korea.

Background: Primary sclerosing cholangitis (PSC) is well known as one of the extraintestinal manifestations of ulcerative colitis (UC). However, the prevalence of PSC in UC patients together with the clinical characteristics and outcomes of UC associated with PSC (UC‐PSC) are not clear in Asians. Methods: We retrospectively reviewed the medical records of UC patients who were registered and followed up at the Asan Medical Center. The prevalence of PSC in UC and the clinical features of UC‐PSC compared with matched UC without PSC were investigated. Results: A total of 1849 patients diagnosed with UC between July 1977 and September 2009 were reviewed. Among these, 21 UC‐PSC patients (1.1%) were identified. The cumulative probability of PSC after diagnosis of UC was 0.71% after 1–5 years, 1.42% after 10 years, 2.59% after 15 years, and 3.35% after 20–25 years. Compared with 63 matched UC alone patients, UC‐PSC showed pancolitis (95.2%), rectal sparing (38.1%), and backwash ileitis (42.9%) more frequently (P < 0.001). During follow‐up, three of 21 UC‐PSC patients (14.3%) were diagnosed with colorectal neoplasia and three patients (14.3%) died of PSC‐associated complications. UC‐PSC patients were associated with increased probability of colorectal neoplasia development (P = 0.036) and a trend toward increased mortality compared with the UC alone group. Conclusions: The prevalence of PSC in Korean UC patients appears to be lower than that of Western patients. Similar to Caucasians, UC‐PSC shows unique colonoscopic features and is associated with more frequent colorectal neoplasia development and poor prognosis in Korea. (Inflamm Bowel Dis 2010;)

Combined aberrant expression of E-cadherin and S100A4, but not β-catenin is associated with disease-free survival and overall survival in colorectal cancer patients

Background/AimsEpithelial-to-mesenchymal transition (EMT) in cancers is related to metastasis, recurrence, and poor prognosis. We evaluated whether EMT-related proteins can act as prognostic biomarkers in colorectal cancer (CRC) patients.MethodsWe evaluated the expression of E-cadherin, β-catenin, and S100A4 by immunohistochemistry (IHC) in 333 CRC tissues from the tumor center and invasive margin. Tumor budding, cell grade, tumor stage, type of tumor growth, peritumoral lymphocyte infiltration (TLI), and perineural- or lymphovascular invasion were evaluated as pathological parameters. mRNA levels of E-cadherin, N-cadherin, β-catenin, and S100A4 from 68 specimens from the same set were analyzed by real time quantitative RT-PCR.ResultsLoss of E-cadherin, nuclear β-catenin, and gain of S100A4 were higher in the invasive margin than in the tumor center. Loss of E-cadherin was associated with cell grade, macroscopic type, perineural invasion, and tumor budding, β-catenin with microsatellite instability and tumor site, and S100A4 with growth type, macroscopic type, AJCC stage, lymphovascular invasion, and perineural invasion. The aberrant expression of E-cadherin and S100A4 not β-catenin in the invasive margin was a significant and independent risk factor for disease-free and overall-survival by multivariate analysis, along with AJCC stage and perineural invasion. mRNA levels of β-catenin and S100A4 were correlated with the IHC findings at the tumor invasive margin. E-cadherin and N-cadherin showed a weak inverse correlation.ConclusionsThe combination of loss of E-cadherin and gain of S100A4 in the tumor invasive margin can be used to stratify patients with the same AJCC stage into different survival groups.Virtual slidesThe virtual slides for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/9398289629244673

Western-style diets induce macrophage infiltration and contribute to colitis-associated carcinogenesis.

Background and Aim:  A Western‐style diet (WD) is known to play an important role in inflammatory bowel disease and colon carcinogenesis. The purpose of this study was to understand the role of macrophages in WD‐induced colitis associated with carcinogenesis.

Eradication Rates of Helicobacter pylori in Korea Over the Past 10 years and Correlation of the Amount of Antibiotics Use: Nationwide Survey.

The efficacy of proton‐pump inhibitor–amoxicillin–clarithromycin therapy for H. pylori eradication has decreased over time.

Clinical features and predictors of clinical outcomes in Korean patients with Crohn's disease: A Korean Association for the Study of Intestinal Diseases multicenter study

Although differences in genetic susceptibility and the clinical features of Crohns disease (CD) have been reported between Asian and Caucasian patients, the disease course and predictors of CD in Asians remains poorly defined. The study therefore aimed to investigate factors predictive of the clinical outcomes of patients with CD in a Korean population.

Near-Infrared Fluorescence Imaging Using a Protease-Specific Probe for the Detection of Colon Tumors

BACKGROUND/AIMS Early tumor detection is crucial for the prevention of colon cancer. Near-infrared fluorescence (NIRF) imaging using a target-activatable probe may permit earlier disease detection. Matrix metalloproteinases (MMPs) participate in tumorigenesis and tumor growth. The aim of this study was to determine whether NIRF imaging using an MMP-activatable probe can detect colon tumors at early stages. METHODS WE UTILIZED TWO MURINE COLON CANCER MODELS: a sporadic colon cancer model induced by azoxymethane (AOM), and a colitis-associated cancer model induced by a combination of AOM and dextran sodium sulfate (DSS). Colonic lesions were analyzed by histologic examination, Western blotting, immunohistochemical staining, and NIRF imaging using an MMP-activatable probe. RESULTS Multiple variable-sized tumors developed in both models and progressed from adenomas to adenocarcinomas over time. At the early stage of the AOM/DSS model, diffuse inflammation was observed within the tumors. MMP expression increased progressively through normal, inflammation, adenoma, and adenocarcionoma stages. NIRF signal intensities were strongly correlated with each tumor stage from adenoma to adenocarcinoma. NIRF imaging also distinguished tumors from inflamed mucosa. CONCLUSIONS NIRF imaging using a protease-activatable probe may be a useful tool for early tumor detection. This approach could translate to improve the endoscopic detection of colon tumors, especially in patients with inflammatory bowel disease.

Prospective Randomized Trial of Six-Month versus Nine-Month Therapy for Intestinal Tuberculosis

ABSTRACT Intestinal tuberculosis (TB) continues to be a common disease worldwide. However, the optimal duration of anti-TB medication has not been well established. We therefore compared the efficacy of 6-month and 9-month therapy in the treatment of intestinal TB. Ninety patients definitely diagnosed with intestinal TB were randomized into 6-month (n = 45) or 9-month (n = 45) treatment groups, prospectively. The primary end point was complete response, defined as endoscopic healing of active lesions. Patients were followed up monthly for 3 months after therapy initiation, then every 3 months until the end of therapy, and finally 1 year later. Relapse was assessed 1 year after the end of therapy by patient interview and colonoscopy. Baseline characteristics were similar in the 6-month and 9-month groups. Intention-to-treat analysis revealed no significant differences between the two groups in complete response (6-month group, 93.3%; 9-month group, 91.1%; P = 1.00) or recurrence rate (6-month group, 2.4%; 9-month group, 0.0%; P = 1.00). Median follow-up duration was 39 months in the 6-month group and 32 months in the 9-month group. No surgery was performed on any patient in either group. In conclusion, the 6-month therapy was as effective as 9-month therapy in patients with intestinal TB and may have the additional benefits of reduced treatment cost and increased compliance.