A weighted scoring system (Dental Panoramic Radiograph Score) taking into consideration the nature, extent, and site of osseous and dental changes on dental panoramic radiographs in familial adenomatous polyposis is described. The weighting takes into consideration the incidence of the anomaly in the general population. The reliability of the system was tested by application to 85 people known to be affected by clinical or mutation analysis, 30 people lacking mutation in the adenomatous polyposis gene, and 19 people shown to be at low risk (<1%) by linkage analysis. Using the highest thresholds, a specificity of 100% and sensitivity of -68% was obtained. Ifall positive findings were considered as significant, sensitivity was increased to -82% but the specificity was reduced to -88%. Significant DPRS findings were observed at a significantly higher frequency in patients aged over 20 compared to the patients aged 20 and under. Overall, 68% ofthe affected subjects had significant changes, and -18% had normal appearance on DPR, with the remainder having changes classified as minimal or equivocal.(J Med Genet 1995;32:458-464)
Stem cells are responsible for maintaining differentiated cell numbers during normal physiology and at times of tissue stress. They have the unique capabilities of proliferation, self-renewal, clonogenicity and multi-potentiality. It is a widely held belief that stem-like cells, known as cancer stem cells (CSCs), maintain tumours. The majority of currently identified intestinal stem cell populations appear to be rapidly cycling. However, quiescent stem cell populations have been suggested to exist in both normal intestinal crypts and tumours. Quiescent CSCs may have particular significance in the modern management of colorectal cancer making their identification and characterisation a priority. In this review, we discuss the current evidence surrounding the identification and microenvironmental control of stem cell populations in intestinal crypts and tumours as well as exploring the evidence supporting the existence of a quiescent stem and CSC population in the gut and other tissues.
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