Abstract
To investigate the problem of photo sensitization in pellagrins, need has been felt for quantitative in vitro methods. The observations here described were made with the hope of aiding in the development of such methods.
As a sensitizing agent yellow eosin (National Analine and Chemical Company) has been used. The light source was a nitrogen-filled tungsten filament lamp of 1500 watts, operated at 115 volts by alternating current. The suspension of erythrocytes was contained throughout exposure to light and measurement of degree of hemolysis in standard Pyrex test tubes of 16 mm. outside diameter with walls 1.5 mm. thick. Equal exposure of each tube was insured by placing the tubes in a device to be described in detail elsewhere. This apparatus moved tubes in a circle 30 cm. in diameter about the light source at the approximate center, while the tubes were immersed in a constant temperature waterbath at 37.5° C. and received light through plane windows of plate glass 3 mm. thick. The layer of tap water between the tube and the plate glass was 2 mm. where the tube's circumference came closest to the window. Adequate provision for aeration and maintenance of suspension was provided. Human blood from finger prick was allowed to fall into 0.85% NaCl solution made sufficiently alkaline to give a pink color with phenol red by the addition of 0.1 N NaOH and washed by centrifugation 3 times in specimens of the same solution. This cell suspension was added in 0.2 cc. quantities, measured from pipettes of the between-marks type into 5 cc. quantities of the various solutions which were under study. The final concentration of erythrocytes was about 15,000 per mm3; it was kept close to this figure by adjusting the concentration of the heavy suspension as was indicated by photometer readings of the trial dilutions.
Get full access to this article
View all access options for this article.