Die Reziprozitätsregel in der Photobiologie

Abstract

According to the rule of Bunsen and Roscoe, a photochemical reaction is directly proportional to the total energy dose, irrespective of the time over which this dose is delivered. To date few studies have addressed the validity of this rule in experimental and applied photobiology. Most of these data point to the fact that the rule of reciprocity is invalid or of limited validity for many photobiological reactions. For UV-induced cell death, photocarcinogenesis, psoralen photochemistry, and the effects of low level laser radiation it has been shown that at a constant total dose, the intensity of the source is a major factor that determines quality and quantity of the response. In clinical photomedicine systematic investigations on the reciprocity of exposure time and radiation intensity are lacking. Such studies are urgently needed since it can be concluded from experimental evidence, that their results might lead to therapeutic regimens with an improved therapeutic index, i.e. maximized therapeutic efficacy with minimized adverse reactions.

Photodynamic Inactivation of Mammalian Viruses and Bacteriophages

“…In fact, if the number of photons is higher than this limit, the antimicrobial effect will decrease because the dye in suspension will not absorb all the excess light [160]. Schindl et al [161] referred that the biological effect of light depends on the fluence, irrespective of the time over which this dose is delivered. Maclean et al [162] also indicate that the inactivating light may be applied at high irradiance over a short time or at lower irradiance over a longer time.…”

Photodynamic Therapy with Red Light and 5-Aminolaevulinic Acid for Herpes Simplex Recurrence: Preliminary Results

“…Others studies demonstrate more viral inactivity at lower, compared with higher, fluence rates for the same total fluence (9, 12). Schindl et al (13) reported that the total photodynamic damage of light depends on the fluence, irrespective of the fluence rate. However, it is difficult to compare clinical results obtained using different photosensitizers, light sources and doses of light.…”

Photochemistry — development and achievements

“…There is no reciprocity when a damage (e.g. of DNA) is produced (Schindl et al, 2001). Along with the mentioned, generally valid laws, there are a few rules and principles describing and explaining particular photochemical and photophysical processes.…”