In a previous study1 the average fasting serum carotene in normal persons estimated by the White and Gordon method2 was reported as 0.109 mg. per hundred cubic centimeters. In diabetic patients the average was 0.262 mg. per hundred cubic centimeters. In the present study all the diabetic patients had clinical evidence of carotenemia, as shown by pigmentation of the palms of the hands, soles of the feet or subconjunctival fat. The blood was taken three hours after the break fast meal. We have found that the serum carotene does not rise after a meal unless a significant amount of carotene is taken with the meal.3 then made up to a volume of from 10 to 20 cc, depending on the intensity of color. The extracted carotene was read in a photo-electric colorimeter.4 A blue Jena glass filter BG 12 with a maximum transmission at approximately 425 millimicrons was used, as this was nearest to the maximum absorption band of carotene.
Calibration curves done with crystalline carotene (S. M. A.) both in petroleum ether (boiling point from 40 to 60 C.) and cyclohexane (boiling point 81 C), showed the extinction values to be the same in the two solvents (table 1). Cyclohexane is superior as a solvent because of its slower rate of evaporation. The accompanying chart is a plot of the concentration of crystalline carotene against the percentage of absorption of light.
STUECK GH, FLAUM G, RALLI EP. THE SERUM CAROTENE IN DIABETIC PATIENTS: WITH CLINICAL EVIDENCE OF CAROTENEMIA AS DETERMINED BY THE PHOTO-ELECTRIC COLORIMETER. JAMA. 1937;109(5):343–344. doi:10.1001/jama.1937.02780310021006
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