Ulcerative Colitis: Lam SK

Ouyang Q, Tandon R, Goh KL, Pan GZ, Fock KM, Fiocchi C, Lam SK, Xiao SD. · Department of Gastroenterology, West China Hospital, Sichuan University, Chengdu, China. · J Gastroenterol Hepatol. · Pubmed #17074013 No free full text.

Abstract: At the present there are no large-scale epidemiologic data on inflammatory bowel disease (IBD) in the Asia-Pacific region, but several studies have shown an increased incidence and prevalence of IBD in this region. Compared to the West, there appears to exist a time lag phenomenon. With regard to the two main forms of IBD, ulcerative colitis (UC) is more prevalent than Crohn's disease (CD). In addition to geographic differences, ethnic differences have been observed in the multiracial Asian countries. Moreover, the genetic backgrounds are different in the Asian compared to Western patients. For instance, NOD2/CARD15 variants have not been found in Asian CD patients. In general, the clinical course of IBD seems to be less severe in the Asia-Pacific region than in Western countries. Diagnosis of IBD in this region poses special problems. The lack of a gold standard for the diagnosis of IBD, and the existence of a variety of infectious enterocolitis with similar manifestations to those of IBD make the differential diagnosis particularly difficult. So far, Western diagnostic criteria have been introduced for the diagnosis of IBD. A stepwise approach to exclude non-IBD enterocolitis also must be introduced, and a definite diagnosis must include typical histological features. In some patients, follow up and therapeutic trials might be necessary to obtain a definitive diagnosis. A better understanding of the pathogenesis of IBD will allow the development of better diagnostic markers. The management of IBD also poses some special problems in the Asia-Pacific Region. There is often a delay in using proper medications for IBD, and alternative local remedies are still widely used. With a combination of Western guidelines and regional experiences, similar principles can be used for induction and maintenance of remission. A stepwise selection of medications is advocated depending on the extent, activity and severity of the disease. Comprehensive and individualized approaches are suggested for different IBD patients. Deeper understanding of disease pathogenesis and the unique characteristics of IBD in the Asia-Pacific region, combined with reasonable and practical guidelines for drug management and the future use of biological agents would improve the therapeutic outlook of IBD in this region.

Wang WP, Guo X, Koo MW, Wong BC, Lam SK, Ye YN, Cho CH. · Department of Pharmacology, Faculty of Medicine, The University of Hong Kong, Hong Kong, People's Republic of China. · Am J Physiol Gastrointest Liver Physiol. · Pubmed #11447040 links to  free full text

Abstract: Preliminary studies showed that the inducible form of heme oxygenase (HO-1) was induced and played a protective role in the process of inflammation. The present study investigated the possible role of HO-1 in 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced colitis in rats. We measured HO-1 activity in TNBS-induced colitis in rats and analyzed the severity of colitis along with altered HO activity by assessing lesion area and myeloperoxidase activity. HO-1 mRNA and protein expressions were determined at different time points after TNBS induction. Free radical production and inducible nitric oxide synthase (iNOS), which participate in oxidative injury, were also assayed. HO activity and HO-1 gene expression increased markedly after TNBS induction. Administration with tin mesoporphyrin (SnMP), a HO inhibitor, potentiated the colonic damage along with a reduction in HO-1 activity. Furthermore, the reduction of HO-1 expression by SnMP also enhanced reactive oxygen species and iNOS expression, both of which were dramatically increased after the TNBS enema. L-Arginine pretreatment further aggravated the injurious action of SnMP. Our results indicate that HO-1 plays a protective role in the colonic damage induced by the TNBS enema, and the preventive effects probably result from decreased free radical production and inhibition of iNOS expression in colonic tissues.