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Topical mitomycin C chemotherapy for conjunctival melanoma and PAM with atypia.

AIM: To evaluate topical mitomycin C (MMC) chemotherapy in the treatment of conjunctival melanoma and primary acquired melanosis with atypia. METHODS: In a phase I clinical trial, 10 patients with conjunctival melanoma and/or primary acquired melanosis with atypia were treated with topical MMC 0.04% four times daily. Four patients were given MMC for 28 days as a primary treatment. Six patients were treated with MMC for 7 days after excision and cryotherapy in an effort to improve local control. In this series, 10 patients have been followed for an average of 29 months. RESULTS: All patients were noted to develop transient keratoconjunctivitis during treatment. One patient also developed a transient corneal epithelial defect. Decreased conjunctival pigmentation was noted in the four patients where topical chemotherapy was used as a primary treatment. Nodular tumours were resistant to topical MMC chemotherapy. Of the six patients treated within 2 weeks after primary excision and cryotherapy, there has been no tumour recurrence or symblepharon formation. Nine of the 10 study patients have maintained within one line of their pretreatment visual acuity. No retinal or optic nerve toxicity was noted. CONCLUSION: Since no complications which might preclude further investigation of topical MMC chemotherapy occurred, it was concluded that topical MMC chemotherapy was tolerated as a treatment for conjunctival melanoma and primary acquired melanosis with atypia.

Administration, Topical↗

Representation of mutation pressure and selection pressure by PAM matrices.

This paper analyses the relationship between the mutation data matrix 1PAM/PET91, representing the effect of both mutation and selection pressures exerted on 16130 homologous proteins of different organisms, and a mutation probability matrix (1PAM/MPM) representing the effect of pure mutation pressure on protein coding of the Borrelia burgdorferi genome. The 1PAM/PMP matrix was derived with the help of computer simulations, which used empirical nucleotide substitution rates found for the B. burgdorferi genome. Here, it is shown that the frequency of amino acid occurrence is strongly related to their effective survival time. We found that the shorter the turnover time of an amino acid under pure mutation pressure, the lower its fraction in the proteins coded by the genome and the more protected by selection pressure is its position in proteins. Results of analyses suggest that during evolution the mutational pressure has been optimised to some extent to the selection requirements.

Algorithms↗