The Physiological Effects of Radiant Energy

Abstract

Skin.-The specific effects of long wave ultraviolet radiation are different from those of short wave. Following irradiation with energy extending from 320 to 480 mJ.' a marked, deep red erythema is produced. The maximum effect is observed at 385 m,u., with two weaker maxima at 360 and 408 mJ.'. If the intensities are so chosen that the same degree of erythema is produced at 297 and 385 mJ.', that at 385 mJ.' reaches its maximum in two to three hours, while that at 297 mJ.' is just becoming noticeable. Twelve hours after ir radiation both show maximal reddening, but the color obtained at 297 mJ.' is carmine red, at 385 brown red; forty-eight hours after, the erythema produced at 385 mJ.' is brown, that at 297 mJ.' still maximally red. Five weeks later, that at 385 mJ.' is still strongly brown, while that obtained at 297 mJ.' is barely pigmented. A slight erythema at 385 mJ.' produces marked tanning, the same degree of erythema at 297 mJ.' hardly any. The erythema threshold at 385 mJ.' is 500 times greater than at 297 m,u.. The three maxima at 360, 385, and 408 m,u. are probably related to absorption by specific molecules in cells deeper than the horny layer. There is similarity to the absorption maxima of hemin. Irradiation with energy with a maximum at 385 m,u. has special significance in the treatment of tubercular conditions, at 297 mJ.' in the treatment of rickets (48).There are several contributions to thjs relation between spe cific effects of shorter and longer ultraviolet radiation and the pro duction of erythema and tan, including contrasts between the ac tion of sunlight with its wealth of longer ultraviolet rays and its poverty in the shorter, and the energy emitted by various artificial sources (52,71,80,87,113),The pigmentary changes in the skin have been objectively de termined, spectrophotometrically, after irradiation by sunlight (19, 20). The curve of the first effect (hyperemia) indicates active arte rial blood flow; later the curve shows a shift from oxyhemoglobin to reduced hemoglobin indicating blood stagnation and decreasing 21 Annu. Rev. Physiol. 1941.3:21-40. Downloaded from www.annualreviews.org Access provided by University of California -Davis on 02/09/15. For personal use only. Quick links to online content Further ANNUAL REVIEWS

Role of Inflammation in Carcinogenesis

“…In regard to the transformation of benign into malignant tumours, Ewing concludes that some benign growths appear to originate from inflammatory processes and that the involved tissues may present all gradations between single proliferative activity, adenoma, and carcinoma. Laurens (1941) has pointed out that since carcinogenesis by ultra-violet irradiation is usually preceded by severe erythema, it is possible that the production of neoplasia is related to chronic inflammation. In general, *Aided by grants from the U.S. Public Health Service.…”

The Physiological Effects of Radiant Energy

“…Interest in the physiological effects of radiation has been stimu lated in the past fe:w years by further advance in our knowledge of ultraviolet radiation (1,2), by the development of supervoltage x-ray apparatus, and by the invention of the cyclotron with the neutron rays (3) and the large number of temporarily radioactive isotopes provided by it.…”