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A review was undertaken of 22 patients originally sensitized by tetrachlorosalicylanilide (T4CS) in 1960-61 to determine the pattern of cross-reactions to tribromosalicylanilide, bithionol and hexachlorophane. Two sets of patch tests were applied, one covered for 48 hr. with black paper, the other irradiated after 24 hr. by a source of "black light". Readings were taken at 48 and 96 hr. Thirteen of 15 patients re-tested have remained sensitive to T4CS. Fifteen of 22 patients tested gave positive photopatch tests to an "impure" form of T3BS, 11 to a laboratory purified form. Half the patients showed positive 48 hr. conventional tests. These were thought likely to be "masked" photo-reactions. There were 9 positive photo-reactions to bithionol, but only 1 "conventional" positive reaction. Hexachlorophane only gave 2 positive photo-reactions. This low incidence is in line with the findings of other investigations. A group of 6 control patients without photodermatitis gave negative reactions to all agents used for testing. "Black light" provides a useful addition to methods of testing for contact photo sensitizers. [ABSTRACT FROM AUTHOR]

This article presents information on the research paper "The Effect of Structural Alterations of the Erythemal Activity of Furocoumarins (Psoralens)," by M.A. Pathek, J.H. Fellman and K.D. Kaufman. Thirty-six furocoumarin derivatives and forty-two coumarin derivatives were tested for photosensitizing action to ultra-violet light. None of the compounds was more active than psoralen itself. Methyl substitution in several positions reduced the activity, as did substitution with methoxy, amino, nitro, acetyl, acetamino, bromo groupings in the 5 or 8 positions.