Abstract
The beneficial effects of ultra violet light in the treatment of tuberculosis have been known since the pioneer work of Finsen (Bie). 1 More recently the curative effect in intestinal tuberculosis has attracted attention. Experimental proof of the nature of this action, whether a general constitutional effect or a specific inhibitory influence on the growth of the organisms has not been offered.
The bactericidal action of direct ultra-violet irradiation is well known. Eidinow 2 states that it has been shown that an “erythema dose” of ultra violet light applied to the skin of animals increased the hemo-bactericidal power of the blood. Ultra violet light then appears to have both a direct and an indirect bactericidal action, but whether this bactericidal action is possessed by irradiated photosensitive substances is not known. It has been shown that cholesterol irradiated by ultraviolet light and ingested produces some of the biological effects which are produced by direct irradiation. More recently the effect of the cholesterol has been attributed to a contamination, ergosterol, which is usually present in unpurified cholesterol.
It seemed of interest to test the effect of biologically active (irradiated) impure cholesterol upon the growth of tubercle bacilli in vitro.
Experimental: Cholesterol (Merck) was biologically activated by exposure to ultra violet light for one hour at a distance of 50 cm. The source of ultra violet light was a Hanovia, mercury vapor quartz tube. The cholesterol was dissolved in ether, poured into flat dishes and allowed to dry. In this manner a thin film of cholesterol was exposed to the light. This cholesterol was shown to be biologically active because 15 mg. daily prevented the development of rickets in 3 rats on a rickets-producing diet (Steenbock No. 2965), while 3 rats on the same diet that received the same amount of non-irradiated cholesterol developed severe rickets (histological).
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