Mathematical Analysis of Melanocyte Patterns on Danio rerio.

The study of zebrafish skin pattern development could lead to a better understanding of how these patterns are generated and how they evolved. To compare and contrast wild-type (WT) striped and leopardt1 mutant spotted patterns, photographs were taken of the developing fish. Initial observations led to the hypothesis that the black melanocyte spots in leopardt1 mutants were not randomly distributed, but rather were located in "dashed" stripes. To test this, melanocyte-spot-sized transparent grids were overlaid onto photographs and the location of melanocyte clusters was recorded. The grid maps were used to identify whether a black, melanocyte positive, grid area was present adjacent to each melanocyte cluster in each cardinal and intercardinal direction. In addition, Python-based computer programs were used to analyze the photographs at the pixel level. When analyzed using analysis of variance and logistic regression models, the striped and spotted patterns expressed more similarities than expected. In the leopardt1 zebrafish, the spots were organized into dashed stripes that had similar locations to the WT stripes. This research suggests that spotted and striped patterns are related. Further, the leopardt1 spots were farther apart along the dorsal-ventral axis than in the anterior-posterior direction, suggesting that different mechanisms control spacing along these two axes.

Chemoprevention of colorectal cancer: slow, steady progress.

In population-based observational studies, people had lower rates of colorectal cancer if they were taking various agents, including nonsteroidal anti-inflammatory drugs, calcium, and folate. In placebo-controlled trials in patients with familial adenomatous polyposis and in patients with sporadic colon adenomas, nonsteroidal anti-inflammatory drugs reduced the rates of adenomas, and there is a biologic rationale that they would be effective in reducing colorectal cancer as well. Randomized trials of chemopreventive agents are underway in the general population.

Abnormal p53 immunohistochemistry is associated with an increased colorectal cancer-related mortality in patients with ulcerative colitis.

OBJECTIVE: Immunohistochemical evaluation of p53 staining patterns has been considered as a complementary test for dysplasia in ulcerative colitis-related colorectal cancer surveillance, but usefulness would be particularly important if it were a marker associated with a poor prognosis. The aim of this study was to determine whether abnormal p53 staining of the tumor correlated with cancer-related mortality in ulcerative colitis patients. METHODS: An historical cohort study was designed to examine all ulcerative colitis patients who developed colorectal cancer between 1978 and 1997 and who had tumor tissue blocks available for staining. Tissue was recut and stained for abnormal p53 immunohistochemistry using the DO-7 antibody. Tumors were considered to be p53 positive if at least 5% of nuclei in a high power field were positive for staining. RESULTS: Among 75 patients entered in the study, 38 (50.7%) had p53 positive tumors. Fourteen patients (36.8%) with p53 positive tumors died from colorectal cancer, compared to five (13.5%) with p53 negative tumors (p < 0.04, log-rank test). The adjusted relative risk of cancer-related death among patients with p53 positive tumors was 3.03 (95% CI = 1.05-8.73). CONCLUSIONS: Abnormal p53 immunohistochemistry of tumors is associated with a poor prognosis among ulcerative colitis patients who develop colorectal cancer. As such, p53 immunohistochemical staining could be a useful histological marker to complement routine histology in cancer surveillance programs in ulcerative colitis patients.