Squamous metaplasia, treatment

Treatment of squamous metaplasia with inhalation of vitamin A... 

Holtz G, Bresnick E. 1988. Ascorbic acid inhibits the squamous metaplasia that results from treatment of tracheal explants with asbestos or benzo[a]pyrene-coated asbestos. Cancer Lett 42 23-28. 

Hall-Craggs M, Brenner DE, Vigorito RD, Sutherland JC. Acute renal failure and renal tubular squamous metaplasia following treatment with streptozotocin. Hum Pathol 1982 13(6) 597-601. 

Topical tretinoin has also been used as an ophthalmic ointment 0.01% in the treatment of squamous metaplasia associated with dry eyes. In 161 patients with either keratoconjunctivitis sicca or conjunctival cicatricial diseases (Stevens-Johnson syndrome, inactive pemphigoid, radiation-induced dry eye, drug-induced pseudopemphigoid, and toxic epidermal necrolysis) there were no beneficial effects in the former, but significant reversal of conjunctival kerati-nization in the temporal bulbar site in the latter (1). Adverse effects were hmited to blepharoconjunctivitis and resolved on withdrawal. 

Inhalation exposure produced maternal effects, but no developmental or fetoxicity effects were reported. Rats have been administered -butylamine hydrochloride by gavage on days 6-15 postcoitum (sperm-positive = day 0), or inhaled -butylamine (whole-body exposure), 6 h day on days 6-19 postcoitum. Oral -butylamine HCl 1000 mg kg reduced maternal feed consumption, increased early postimplantation losses, reduced fetal and placental weight, retarded skeletal development, and produced malformations 100 mg kg was the no-observed-adverse-effect level (NOAEL) for prenatal developmental toxicity. Inhaled -butylamine produced concentration-dependent nasal epithelial hyperplasia and squamous metaplasia, inflammation, and necrosis the maternal NOAEL was less than 17ppm. There were no treatment-related signs of embryo fetotoxicity particularly, no effects on fetal morphology. The developmental NOAEL was 152 ppm. 

Animal studies to date have failed to show consistent evidence of an anticancer action of vitamin C. Holtz and Bresnick (1988) reported that ascorbic acid inhibited the squamous metaplasia that results from the treatment of tracheal explants with asbestos or benzo(a)pyrene-coated asbestos. Liehr et al. (1989) found that vitamin C could inhibit estrogen-induced renal carcinogenesis in male ham-... 

Vitamin A deficiency is characterized by squamous metaplasia of a variety of epithelia with increased cell proliferation and hyperkeratosis. These changes are also features of some benign dermatoses, for example, psoriasis. Once beneficial effects of oral vitamin A were observed, its use spread to the treatment of other diseases of the epidermis and epidermal appendages, including acne, psoriasis, and basal cell carcinoma. Since the hypervitaminosis A syndrome (see Chapter 13) interfered with long-term therapy with vitamin A, the need arose for synthetic derivatives that could be at least as efficacious as vitamin A and yet be less toxic. The use of isotretinoin and etretinate, as described above, represents the first development of this concept in clinical practice. 

The results of this study, in which a synthetic retinoid was found to have a profound beneficial effect in the treatment of disorders of keratinization, should be of importance to areas other than dermatology. For instance, preneoplastic squamous metaplasia of tracheo-bronchial and urinary bladder epithelia may be other keratinizing disorders of man that could be successfully treated with the synthetic retinoids, as suggested by Sporn . Finally, patients with these cutaneous diseases, which have responded to 13-cis retinoic acid, may provide useful information in the evaluation of newer and potentially more potent and less toxic synthetic retinoids. 

Group and Treatment Number of Rats Squamous Cell Hyperplasia Glandular Hyperplasia Intestinal Metaplasia... 

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