Epithelial cell dysplasia

Dysplasia is a special type of cell adaptation that literally means disordered growth, and it is usually associated with neoplasia or preneoplastic changes. Dysplasia implies a loss in the uniformity of the individual cells and a loss in the normal tissue growth pattern. For example, a dysplastic area involving the epidermal layers of the skin might contain jumbled, atypical epithelial cells with loss of their normal polarity and orderly differentiation. 

Huang, M.T., Deschner, E.E., Newmark, H.L., Wang, Z.-Y, Eerraro T.A., and Conney, A.H., Effect of dietary curcumin and ascrobyl pahnitate on azoxymethanol-induced colonic epithelial cell proliferation and focal areas of dysplasia. Cancer Lett., 64, 117, 1992. 

FIGURE 14.1 A, High-grade dysplasia in Barrett esophagus typically shows strong and diffuse nuclear staining with p53 (B). However, there can be substantial overlap of the patterns of p53 reactivity in epithelial cells that are reactive and those that show low-grade dysplasia. 

Because oral hygienic products are used on a daily basis and some of their contents may be swallowed or absorbed locally, there is always a concern that long-term effects may occur. One noteworthy example was the association of the use of Sanguinaria canadensis root-extract mouthwashes with the development of hyperorthokeratosis, epithelial atrophy, and epithelial atypia/mild dysplasia and an associated squamous cell carcinoma (Allen, 1999 Damm et al., 1999). This phenomenon has been called the sanguinaria-associated leukoplakia syndrome, and evaluation of the 143 known cases... 

A chronic inhalation MRL of 0.008 ppm was derived based on a minimal LOAEL of 0.24 ppm for histological evidence of mild damage to the nasal epithelial tissue (squamous metaplasia, loss of ciliated cells, goblet cell hyperplasia, and mild dysplasia in biopsied tissue) in formaldehyde exposed chemical workers (Holmstrom et al. 1989c). To derive the MRL, the minimal LOAEL was divided by an uncertainty factor of 30 (3 for the use of a minimal LOAEL and 10 for human variability). 

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