Evidence Indirectly Confirming That Plasma Glucose Decreases on Storage at - 20 # { 176 } C

nique reported by Paty et al. (2). The procedure is as follows: Concentrate 3 mL of CSF 80-fold in a Minicon CS 15 spinal fluid concentrator (Amicon Corp., Lexington, MA 02173). Apply concentrated CSF equivalent to 12 zg of IgG to a Titan III cellulose acetate plate (Helena Labs., Beaumont, TX 77704), and electrophorese for 45 mm at a constant voltage of 180 V, using high-resolution sodium barbital buffer, pH 8.8 (Gelman Sciences, Inc., Ann Arbor, MI 48106). Stain in a solution consisting of 5 g of Ponceau S and 75 g of trichloroacetic acid in 1 L of water. Destain and clear in the usual way. Photograph the stained, cleared membranes on a background of fixed white glossy photographic paper, using 35-mm Kodalith high-contrast film, 7ASA (Eastman Kodak Co., Rochester, NY 14650) and exposure times of 2 to 4 s in 0.25-s increments, with an aperture of f22. Identify the oligoclonal bands by visual inspection in transmitted light. Figure 1 shows densitometric scans of the stained cleared membranes and of black-and-white negatives, for a normal patient and a patient with multiple sclerosis. Clearly, the photographic enhancement improves the resolution of the ‘y-globulin region. We think that visual inspection of the photographic negative is the best method for detecting oligoclonal bands. Densitometric scanning of the stained membranes with increased gain did not improve the resolution of the bands. The negative provides a permanent record of the results.