Nuclear DNA analysis of genetics of cancer and dysplasia complicating ulcerative colitis

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1)Assessment of optimum thickness of the sections : This study assessed the optimum thickness of the paraffin embedded sections to determine the true DNA content with a cytophofometric technique in 35 colonic samples from 23 patients with ulcerative colitis and 10 non-colitic patients with colorectal cancer. The 4 ,7 ,10 sections were cut from each samples. The cellular DNA values of these sections were compared with smears from cells detached from the same paraffin embedded tissue. The modal DNA values of the four methods were similar. On the contrary, the frequency of the cells with DNA content higher than 6C value (polyploid cells) did not coincide. The frequency of false negative cases which had polyploid cells in smears but hadn't in sections was 8.6, 0, 5.7 in 4, 7, 10 respective. The frequency of false positive cases was 14.3, 20, 25.7, but 6.3, 6.7, 18.8 in the inactive specimens. Therefore 7 section showed higher sensitivity and specificity. We suqqest that micro spectrophotom … More etric DNA content in ulcerative colitis is better analized with 7 section.2)Application for cancer and dysplasia diagnpsis : The DNA content was measured by microspectrophotometry from 100 specimens in 60 patients with ulcerative colitis including six complicating carcinoma. In dysplastic 23 (77%) of 30 samples showed aneuploidy or polyploidy, whereas in non-dysplastic tissues 50 (94%) of 53 samples were diploid, the difference being statistically significant. Polyploidy was often observed in the non-dysplastic mucosa of the patients complicating cancer or dysplasia. In non-dysplastic patients all sample with inflammation showed diploidy, however 10% of samples without inflammation showed polyploidy. A good correlation was found between the incidence of polyploid cells and the grade of dyspasia. From this study it was assumed that microspectrophotometric measurement of DNA content is useful in the assessment and siagnosis of dysplasia in ulcerative colitis and can be available in the screening of high-risk patients. Less