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Biomedical subjects

P M Choi

Publications and source records attributed to P M Choi.

At least 19 recordsLinked to original sources
PubMed1995

Role of antineutrophil cytoplasmic antibodies in an ethnically distinct population: Korean patients with ulcerative colitis.

OBJECTIVES: Studies have suggested that antineutrophil cytoplasmic antibodies (ANCA), known as a useful diagnostic marker in patients with ulcerative colitis (UC), may have a genetic basis, particularly in association with HLA class II genes. Because most studies examining the role of ANCA in UC have been performed in ethnically undefined populations, we have analyzed ANCA status in an ethnically distinct group of patients with UC. METHODS: Serum samples from 24 Korean patients with a known diagnosis of UC and 58 healthy Koreans were examined for the presence of ANCA, using a fixed neutrophil enzyme-linked immunosorbent assay. ANCA-binding patterns were examined by indirect immunofluorescence. RESULTS: The incidence of ANCA in 83.3% of Korean patients with UC was significantly higher than in controls (p < 0.0001). The mean binding level at a 1:100 dilution and the titer of ANCA were significantly higher in patients with UC than in controls. Among UC patients with ANCA, there was also a high incidence of perinuclear binding pattern. In contrast, there was no relationship between ANCA and age of patients, duration, activity, or extent of disease. CONCLUSIONS: High sensitivity and specificity of ANCA in an ethnically distinct group of patients with UC show that ANCA expression may not be ethnically determined, and they confirm the utility of ANCA as a useful diagnostic indicator of UC in an ethnically diverse groups of patients.

Adult↗
PubMed1995

Colon cancer surveillance.

Colorectal cancer is one of the most important risk factors affecting the long-term outcome of patients with ulcerative colitis. Therefore, an extensive effort has been devoted to prevent and reduce the mortality related to colorectal cancer through cancer surveillance programs. Studies have demonstrated that cancer surveillance can lead to an improved outcome in patients who go on to develop cancer. Given increasing reports of cancer risk in Crohn's disease, further studies examining the potential impact of a similar program in Crohn's disease should be considered.

Biomarkers↗
PubMed1994

Immunomodulator therapy in inflammatory bowel disease.

The introduction of immunomodulator therapy in the treatment of patients with inflammatory bowel disease (IBD) has provided an important tool in modifying the mucosal immune system thought to be important in the pathogenesis of IBD. Currently available immunomodulating agents include azathioprine, 6-mercaptopurine, cyclosporin, and methotrexate. Recent clinical trials have demonstrated that these agents have an important therapeutic role in the treatment of patients who are either refractory or intolerant to traditional medical therapy. They are useful in the induction and maintenance of remission for both ulcerative colitis and Crohn's disease. However, these agents have significant toxicities and limited efficacy. In addition, potential risks of malignancy and infection limit their indiscriminate use. Thus, with the better understanding of the molecular basis of mucosal immunity, innovative immune-modifying therapies, such as antagonists of cytokines and inhibitors of T-cell activation, are being developed. It is likely that these exciting developments will soon result in specific immune modulating therapy with improved efficacy and reduced toxicity in the treatment of patients with IBD.

Antibodies, Monoclonal↗
PubMed1994

Cholangiocarcinoma and Crohn's disease.

Cholangiocarcinoma is an infrequent complication of inflammatory bowel disease. Although increasing numbers of cholangiocarcinomas are being reported in association with ulcerative colitis, the occurrence of this disease in patients with Crohn's disease is rare. To understand this complication better, we have reported the case of a patient with Crohn's disease in whom cholangiocarcinoma subsequently developed and reviewed the literature.

Cholangiocarcinoma↗
PubMed1994

Similarity of colorectal cancer in Crohn's disease and ulcerative colitis: implications for carcinogenesis and prevention.

Colorectal cancer is the most frequent malignant complication in patients with inflammatory bowel disease. Eighty patients with colorectal cancer complicating Crohn's disease (CD) or ulcerative colitis (UC) with median ages at diagnosis of colorectal cancer of 54.5 years and 43.0 years respectively were studied. The median duration of disease to the diagnosis of cancer was long (CD 15 years; UC 18 years). Most cancers developed after more than eight years of disease (CD 75%; UC 90%). Patients with multiple carcinomas at diagnosis were equally common (CD 11%; UC 12%). Carcinoma occurred in the area of macroscopic disease in most patients (CD 85%; UC 100%). Mucinous and signet ring histological features were equally common (CD 29%; UC 21%). Dysplasia was present with similar frequency in both diseases (CD 73%; UC 79%). The overall five year survival rates were also similar (CD 46%; UC 50%). These findings show that carcinomas complicating CD and UC have strikingly similar clinicopathological features and suggest that a common underlying process, such as chronic inflammation, maybe important in the pathogenesis of colorectal carcinoma.

Adolescent↗
PubMed1994

Safety of surveillance colonoscopy in long-standing ulcerative colitis.

OBJECTIVE: Because of the increased risk of colorectal cancer in patients with long-standing ulcerative colitis, colonoscopic surveillance for the detection of dysplasia is currently recommended as a method of identifying high-risk patients. However, the hazard of colonoscopy with multiple biopsies in such patients is not well known. Our objective was to assess the safety of surveillance colonoscopy in patients with long-standing ulcerative colitis. METHODS: To accomplish our objective, we conducted a retrospective analysis of results and follow-up of surveillance colonoscopies. RESULTS: A total of 6,727 biopsies were obtained during 384 colonoscopies, with a median of 17 biopsies per colonoscopy. Nineteen studies were performed in a setting of underlying stricture. A single complication of a silent perforation occurred in a patient with an underlying stricture. No instances of bleeding, infection, respiratory distress, myocardial infarction, or death resulted from the procedure. CONCLUSION: Our findings suggest that surveillance colonoscopy with multiple biopsies is a relatively safe procedure. Given increasing evidence of the survival benefit derived from the procedure, we believe these results render further support for the current practice of surveillance colonoscopy in patients with ulcerative colitis.

Adult↗
PubMed1993

Colonoscopic surveillance reduces mortality from colorectal cancer in ulcerative colitis.

BACKGROUND: To control the increased risk of colorectal carcinoma in patients with long-standing ulcerative colitis, surveillance colonoscopy is widely recommended. METHODS: To assess the role of colonoscopic surveillance in affecting colorectal carcinoma-related mortality, an outcome analysis was performed. RESULTS: Among the total of 41 patients who developed carcinoma associated with ulcerative colitis, 19 patients were under colonoscopic surveillance and 22 patients were not. Carcinoma was detected at a significantly earlier Dukes' stage in the surveillance group (P = 0.039). Four patients in the surveillance group died, compared with 11 patients in the no-surveillance group. The 5-year survival rate was 77.2% for the surveillance group and 36.3% for the no-surveillance group (P = 0.026). CONCLUSIONS: These results suggest that colonoscopic surveillance reduces colorectal carcinoma-related mortality by allowing the detection of carcinoma at an earlier Dukes' stage.

Adolescent↗
PubMed1991

The modulation of growth by HMBA in PKC overproducing HT29 colon cancer cells.

To examine whether protein kinase C (PKC) plays a role in mediating growth inhibitory effects of hexamethylene bisacetamide (HMBA) we compared a control H29 colon cancer cell line to a derivative, HT29-PKC7, that overexpresses high levels of PKC beta 1. We found that although HMBA markedly inhibited the growth of the control cells, no inhibition was seen with the HT29-PKC7 cells. On the other hand the tumor promoter 12-0-tetradecanoyl-phorbol-13 acetate inhibited the growth of HT29-PKC7 cells, but no inhibition was seen with the control cells. Maximum inhibition of the growth of both cell lines was obtained by combined treatment with HMBA and TPA. These results may be relevant to the use of HMBA in combination with other agents in the therapy of specific cancers.

Acetamides↗
PubMed1990

Overexpression of protein kinase C in HT29 colon cancer cells causes growth inhibition and tumor suppression.

By using a retrovirus-derived vector system, we generated derivatives of the human colon cancer cell line HT29 that stably overexpress a full-length cDNA encoding the beta 1 isoform of rat protein kinase C (PKC). Two of these cell lines, PKC6 and PKC7, displayed an 11- to 15-fold increase in PKC activity when compared with the C1 control cell line that carries the vector lacking the PKC cDNA insert. Both of the overexpresser cell lines exhibited striking alterations in morphology when exposed to the tumor promoter 12-O-tetradecanoyl-phorbol-13-acetate (TPA). Following exposure to TPA, PKC6 and PKC7 cells displayed increased doubling time, decreased saturation density, and loss of anchorage-independent growth in soft agar; but these effects were not seen with the C1 cells. Also, in contrast to the control cells, the PKC-overproducing cells failed to display evidence of differentiation, as measured by alkaline phosphatase activity, when exposed to sodium butyrate. In addition, the PKC-overexpresser cells displayed decreased tumorigenicity in nude mice, even in the absence of treatment with TPA. These results provide the first direct evidence that PKC can inhibit tumor cell growth. Thus, in some tumors, PKC might act as a growth-suppressor gene.

Animals↗