190 .JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS g'- •.:.::'i:...x"':. : .... -?•. • "•'• .... •%":%•'. -•. •:.,• •5-• ' .?. -:.•: - , -* -* •:. .-• ._•-• '.":. • '• "- ,:. .-,¾.4?:: ...' .......... -5 .... .:: " ... ., , ..,:.a"'*: .. :. •7..*• '*': . '. ' * .... .,• . -- ....: ......... . ..... .z ....... ./%*. •.•%. ._ . ..... .. •' :•:.... '•..:..." -- .,--- ........•?...... . .... :• '..• , : ."? e . ..... .•. •,. ,½•.•(•.•' .,: .,,•.::.. Figure I. Illustrations of guinea pig sloughing produced by increasing i•lcrcments of P. oi/ale cells added to artificial sebum. Photographs taken 5 days after initial application of the cell plus lipid mixture. Quadrant numbers refer to snbjectivc severity score in each quadrant

MODEL SYSTEM FOR DANDRUFF INVESTIGATION 191 of sloughing being recorded 5 days after application. The sloughing re- action was graded subjectively on a 0-4 scale after the treated areas were reclipped, with the most severe reactions being given the highest score. Photographs showing' the severity of sloughing relative to scores are shown in Fig. 1. Oleic acid (reagent grade) was applied to the test sites at the indicated concentrations in a propylene glycol vehicle. Control sites indicated that the vehicle was not irritating. Organisms Representative strains of the major constituents of the scalp microbial population were utilized in this study. These strains were isolated from scalp washings obtained by placing a glass collar (25-mm diameter) firmly in place on the scalp and scrubbing with 5 ml of 0.05M phosphate buffer (pH 7.0) for 30 sec. Fresh cell preparations harvested from broth media were routinely used. The P. ovale strain was isolated using the medium described in Table II. Table II Formula of Medium for Growth of P. o•ale and Scalp Diphtheroid g/1. Tryp ticase soy broth (BBL) 30.0 Tween 40 1.0 Oleic acid 0.1 1N Lactic acid 20.0 Streptomycin sulfate • 0. 005 Penicillin G a 0. 045 Cycloheximide • 0. 025 pH 6.0 Omitted from diphtheroid medium. For growth and maintenance of pure cultures, the antibiotics in the above formulation were omitted. Incubation was normally for approxi- mately 14 days at 37øC at which time the cells were harvested by centrif- ugation or filtration. Diphtheroids were cultured on the above medium minus antibiotics. In every instance, these organisms were grown anaerobically at $7øC and harvested by centrifugation after 5 days of incubation. These cultures have been identified as Corynebacterium aches.