WHEN HAIR infected with Microsporum audouini is boiled in water to which a small amount of potassium hydroxide has been added, the fluorescent substance is removed and the remaining hair is lusterless and free from pigment. Spectrophotometric studies show a striking similarity between the spectra of hair infected with M. audouini and those of noninfected gray hair. These studies indicate that a chemical reaction occurs between the normal pigment of the hair and the invading fungus. In vitro studies show that melanin is produced by the action of tyrosine and tyrosinase, and that this reaction is inhibited by M. audouini or by the elaboration of some inhibiting substance produced by this organism when grown on artificial media (Table).
The liquid dextrose Sabouraud's medium used in this series of experiments contained: 1% Neopeptone: 2% dextrose; 0.2% agar, and 0.1% yeast extract. Twenty-five cubic centimeters was placed in each of six
ROBINSON HM, FIGGE FHJ, BERESTON ES. INHIBITION OF TYROSINE-TYROSINASE REACTION BY MICROSPORUM AUDOUINI: Preliminary Report. AMA Arch Derm Syphilol. 1953;68(4):428–429. doi:10.1001/archderm.1953.01540100068011
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