The incidence and prevalence rates of inflammatory bowel disease (IBD) in Korea are still low com... more The incidence and prevalence rates of inflammatory bowel disease (IBD) in Korea are still low compared with those of the Western countries, but have been increasing rapidly during the past decades. The data from Japan and Korea suggest that westernization in lifestyles including dietary habits as well as environmental changes caused by industrialization and urbanization are probably responsible for the change in the incidence. Also, the results of the genetic studies from Japan and Korea suggest that there may be some differences in candidate genes which predispose to IBD between Asian and Western countries. The prognosis of IBD in Korea seems to be better than that in the Western countries. It is not certain, however, whetherthis difference means intrinsic difference of IBD between Korea and Western countries, or reflects thepresence of some other factors such as temporal bias. Although further studies are needed, current data suggest that the prognosis of IBD in Korea is at least ...
Background The precise role of cytomegalovirus (CMV) in ulcerative colitis (UC) remains disputed.... more Background The precise role of cytomegalovirus (CMV) in ulcerative colitis (UC) remains disputed. We evaluated the association of CMV-specific host immune responses and systemic or local viral replication with responses to systemic steroids in patients with moderate to severe UC. Methods Patients who were hospitalized for moderate to severe UC between April 2015 and June 2016 were enrolled. At baseline, all enrolled patients underwent CMV-specific enzyme-linked immunospot assays, quantitative polymerase chain reaction (qPCR) analysis of blood and colonic tissue for CMV viral load, histopathological testing for CMV in colonic tissue by hematoxylin and eosin staining, and immunohistochemical (IHC) analysis. Clinical responses to steroid therapy based on the Oxford index were assessed on day 3. Results Of the 80 patients evaluated, 28 (35.0%) had poor responses to steroid therapy on day 3 of intensive treatment. The presence of inclusion bodies (32.1%) and high-grade (≥3) positivity on...
Canadian Journal of Gastroenterology and Hepatology, 2014
BACKGROUND: Appendiceal orifice inflammation (AOI) is a common ‘skip lesion’ in patients with ulc... more BACKGROUND: Appendiceal orifice inflammation (AOI) is a common ‘skip lesion’ in patients with ulcerative colitis (UC). However, other skip lesions are less well known.OBJECTIVE: To evaluate the atypical distribution of UC lesions, other than AOI, in terms of their frequency, pattern, risk factors and prognostic implications.METHODS: A retrospective analysis of colonoscopic findings and clinical course of 240 adult UC patients who were initially diagnosed at Asan Medical Center (Seoul, South Korea) was performed.RESULTS: Of 240 patients, 46 (19.2%) showed an atypical distribution of lesions at initial colonoscopy: eight (3.3%) had rectal sparing (segmental-type UC); and 38 (15.8%) had patchy/segmental skip lesions other than AOI. Skip lesions were detected more frequently in proximal segments of the colon than in distal segments (P=0.001). An atypical distribution was more common in patients with AOI (31.3%) than in those without AOI (10.6%; P<0.001). The clinical course of patien...
The incidence of Crohn’s disease (CD) increases steadily in Asia, but is still quite low compared... more The incidence of Crohn’s disease (CD) increases steadily in Asia, but is still quite low compared with Western countries.1 So far, over 140 susceptibility loci to CD have been identified in Caucasians through genome-wide association studies (GWASs) and meta-analyses.2 Recent GWASs in Korean and Japanese populations identified a few more susceptibility loci, but could not replicate many established CD loci.3 ,4 A Japanese large scale replication study consisting of 1311 cases and 6585 controls could replicate less than half of 71 CD susceptibility loci identified in Caucasians.5 Particularly, it aroused concern that such well-established loci as ATG16L1 and NOD2 have not been replicated. It was unclear whether the lack of association was due to limited statistical power, different linkage disequilibrium (LD) structure, …
Postpolypectomy surveillance has become a major indication for colonoscopy as a result of increas... more Postpolypectomy surveillance has become a major indication for colonoscopy as a result of increased use of screening colonoscopy in Korea. In this report, a careful analytic approach was used to address all available evidences to delineate the predictors for advanced neoplasia at surveillance colonoscopy and we elucidated the high risk findings of the index colonoscopy as follows: 3 or more adenomas, any adenoma larger than 10 mm, any tubulovillous or villous adenoma, any adenoma with high-grade dysplasia, and any serrated polyps larger than 10 mm. Surveillance colonoscopy should be performed five years after the index colonoscopy for those without any high-risk findings and three years after the index colonoscopy for those with one or more high risk findings. However, the surveillance interval can be shortened considering the quality of the index colonoscopy, the completeness of polypectomy, the patient's general condition, and family and medical history.
C-reactive protein (CRP) is a serologic activity marker in Crohn's disease (CD), but it may b... more C-reactive protein (CRP) is a serologic activity marker in Crohn's disease (CD), but it may be less useful in evaluating CD activity in ileal CD patients. We aimed to investigate the usefulness of CRP as a disease activity marker in CD according to disease location. Korean CD patients in a single hospital were evaluated. Factors associated with elevated CRP concentration at the time of diagnosis of CD and the association between the…
Cytomegalovirus (CMV) reactivations are frequently observed in patients with active ulcerative co... more Cytomegalovirus (CMV) reactivations are frequently observed in patients with active ulcerative colitis (UC), and ganciclovir therapy is effective in patients with steroid-refractory UC. This study aimed to determine the long-term outcomes of CMV reactivation and the long-term therapeutic efficacy of ganciclovir treatment. This retrospective multicenter study included a cohort of 72 patients with moderate-to-severe UC who were evaluated for CMV reactivation at the time of their initial UC flare. Colectomy, disease relapse, and the recurrence rate of CMV reactivation were investigated. The mean duration of follow-up for the 72 patients was 43.16±19.78 months (range, 1 to 67 months). The cumulative colectomy (log-rank, p=0.025) and disease flare-up rates (log-rank, p=0.048) were significantly higher in the CMV-positive group. Of the 11 patients who were successfully treated with ganciclovir in the initial treatment, three patients (27.3%) experienced CMV reactivation, and six patients ...
The incidence and prevalence rates of inflammatory bowel disease (IBD) in Korea are still low com... more The incidence and prevalence rates of inflammatory bowel disease (IBD) in Korea are still low compared with those of the Western countries, but have been increasing rapidly during the past decades. The data from Japan and Korea suggest that westernization in lifestyles including dietary habits as well as environmental changes caused by industrialization and urbanization are probably responsible for the change in the incidence. Also, the results of the genetic studies from Japan and Korea suggest that there may be some differences in candidate genes which predispose to IBD between Asian and Western countries. The prognosis of IBD in Korea seems to be better than that in the Western countries. It is not certain, however, whetherthis difference means intrinsic difference of IBD between Korea and Western countries, or reflects thepresence of some other factors such as temporal bias. Although further studies are needed, current data suggest that the prognosis of IBD in Korea is at least ...
Background The precise role of cytomegalovirus (CMV) in ulcerative colitis (UC) remains disputed.... more Background The precise role of cytomegalovirus (CMV) in ulcerative colitis (UC) remains disputed. We evaluated the association of CMV-specific host immune responses and systemic or local viral replication with responses to systemic steroids in patients with moderate to severe UC. Methods Patients who were hospitalized for moderate to severe UC between April 2015 and June 2016 were enrolled. At baseline, all enrolled patients underwent CMV-specific enzyme-linked immunospot assays, quantitative polymerase chain reaction (qPCR) analysis of blood and colonic tissue for CMV viral load, histopathological testing for CMV in colonic tissue by hematoxylin and eosin staining, and immunohistochemical (IHC) analysis. Clinical responses to steroid therapy based on the Oxford index were assessed on day 3. Results Of the 80 patients evaluated, 28 (35.0%) had poor responses to steroid therapy on day 3 of intensive treatment. The presence of inclusion bodies (32.1%) and high-grade (≥3) positivity on...
Canadian Journal of Gastroenterology and Hepatology, 2014
BACKGROUND: Appendiceal orifice inflammation (AOI) is a common ‘skip lesion’ in patients with ulc... more BACKGROUND: Appendiceal orifice inflammation (AOI) is a common ‘skip lesion’ in patients with ulcerative colitis (UC). However, other skip lesions are less well known.OBJECTIVE: To evaluate the atypical distribution of UC lesions, other than AOI, in terms of their frequency, pattern, risk factors and prognostic implications.METHODS: A retrospective analysis of colonoscopic findings and clinical course of 240 adult UC patients who were initially diagnosed at Asan Medical Center (Seoul, South Korea) was performed.RESULTS: Of 240 patients, 46 (19.2%) showed an atypical distribution of lesions at initial colonoscopy: eight (3.3%) had rectal sparing (segmental-type UC); and 38 (15.8%) had patchy/segmental skip lesions other than AOI. Skip lesions were detected more frequently in proximal segments of the colon than in distal segments (P=0.001). An atypical distribution was more common in patients with AOI (31.3%) than in those without AOI (10.6%; P<0.001). The clinical course of patien...
The incidence of Crohn’s disease (CD) increases steadily in Asia, but is still quite low compared... more The incidence of Crohn’s disease (CD) increases steadily in Asia, but is still quite low compared with Western countries.1 So far, over 140 susceptibility loci to CD have been identified in Caucasians through genome-wide association studies (GWASs) and meta-analyses.2 Recent GWASs in Korean and Japanese populations identified a few more susceptibility loci, but could not replicate many established CD loci.3 ,4 A Japanese large scale replication study consisting of 1311 cases and 6585 controls could replicate less than half of 71 CD susceptibility loci identified in Caucasians.5 Particularly, it aroused concern that such well-established loci as ATG16L1 and NOD2 have not been replicated. It was unclear whether the lack of association was due to limited statistical power, different linkage disequilibrium (LD) structure, …
Postpolypectomy surveillance has become a major indication for colonoscopy as a result of increas... more Postpolypectomy surveillance has become a major indication for colonoscopy as a result of increased use of screening colonoscopy in Korea. In this report, a careful analytic approach was used to address all available evidences to delineate the predictors for advanced neoplasia at surveillance colonoscopy and we elucidated the high risk findings of the index colonoscopy as follows: 3 or more adenomas, any adenoma larger than 10 mm, any tubulovillous or villous adenoma, any adenoma with high-grade dysplasia, and any serrated polyps larger than 10 mm. Surveillance colonoscopy should be performed five years after the index colonoscopy for those without any high-risk findings and three years after the index colonoscopy for those with one or more high risk findings. However, the surveillance interval can be shortened considering the quality of the index colonoscopy, the completeness of polypectomy, the patient's general condition, and family and medical history.
C-reactive protein (CRP) is a serologic activity marker in Crohn's disease (CD), but it may b... more C-reactive protein (CRP) is a serologic activity marker in Crohn's disease (CD), but it may be less useful in evaluating CD activity in ileal CD patients. We aimed to investigate the usefulness of CRP as a disease activity marker in CD according to disease location. Korean CD patients in a single hospital were evaluated. Factors associated with elevated CRP concentration at the time of diagnosis of CD and the association between the…
Cytomegalovirus (CMV) reactivations are frequently observed in patients with active ulcerative co... more Cytomegalovirus (CMV) reactivations are frequently observed in patients with active ulcerative colitis (UC), and ganciclovir therapy is effective in patients with steroid-refractory UC. This study aimed to determine the long-term outcomes of CMV reactivation and the long-term therapeutic efficacy of ganciclovir treatment. This retrospective multicenter study included a cohort of 72 patients with moderate-to-severe UC who were evaluated for CMV reactivation at the time of their initial UC flare. Colectomy, disease relapse, and the recurrence rate of CMV reactivation were investigated. The mean duration of follow-up for the 72 patients was 43.16±19.78 months (range, 1 to 67 months). The cumulative colectomy (log-rank, p=0.025) and disease flare-up rates (log-rank, p=0.048) were significantly higher in the CMV-positive group. Of the 11 patients who were successfully treated with ganciclovir in the initial treatment, three patients (27.3%) experienced CMV reactivation, and six patients ...
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Papers by Suk-kyun Yang