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Proceedings Paper

Primary, secondary, and tertiary effects of phototherapy: a review
Author(s): Mary Dyson
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Paper Abstract

The classification of the cellular effects of phototherapy into primary, secondary and tertiary types is an aid to understanding variation in the predictability of the events that follow its application. Primary effects are generally restricted to the absorption of photons by cytochromes and catalytic interactions with these and other intracellular molecules. If suprathreshold, they stimulate cell activity, initiating secondary anabolic effects in those cells affected by the photons. These events can also be initiated by nonphotonic stimuli. Some of the secondary effects, such as growth factor secretion, can produce effects in cells that did not absorb photons. It is proposed that this group of effects be classified as tertiary. Primary effects are strongly predictable, secondary effects less so, being dependent on cell sensitivity, while tertiary effects are the least predictable, being affected by variation in both the internal and external environment and by intercellular interactions. The investigation of primary and secondary effects of phototherapy can be used to determine which irradiation parameters are ineffective in vitro and therefore cannot be effective in vivo. Since tertiary effects predominate in vivo only clinical testing can demonstrate which parameters are most likely to be effective, and with what level of predictability. It is essential that all relevant exposure conditions be recorded and disseminated if experimental work is to be of clinical value. It is also essential that all relevant information about the target of phototherapy, be it molecule, organelle, cell, healthy volunteer or patient, be recorded and disseminated.

Paper Details

Date Published: 28 February 2006
PDF: 12 pages
Proc. SPIE 6140, Mechanisms for Low-Light Therapy, 614005 (28 February 2006); doi: 10.1117/12.648449
Show Author Affiliations
Mary Dyson, Kings College London/Univ. of London (United Kingdom)

Published in SPIE Proceedings Vol. 6140:
Mechanisms for Low-Light Therapy
Michael R. Hamblin; Ronald W. Waynant; Juanita Anders, Editor(s)

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