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வியாழன், ஆகஸ்ட் 23, 2012

Low-Power Laser Therapy

Low-Power Laser Therapy
Tiina I. Karu
Institute of Laser and Information Technologies
Russian Academy of Sciences
Troitsk, Moscow Region, Russian Federation

In low-power laser therapy, the question is no longer whether light has biological effects but rather  how radiation from therapeutic lasers and LEDs works at the cellular and organism levels and what the optimal light parameters are for different uses of these light sources.
This chapter is organized as follows.
First, Section 48.2 briefly reviews clinical applications and considers one of the most topical issues in low-power-laser medicine today, i.e., whether coherent and polarized light has additional benefits in comparison with noncoherent light at the same wavelength and intensity.
Second, direct activation of various types of cells via light absorption in mitochondria is described.
Primary photoacceptors and mechanisms of light action on cells as well as mechanisms of cellular signaling are considered (Section 48.3). Section 48.4 describes enhancement of cellular metabolism via activation of nonmitochondrial photo acceptors and possible indirect effects via secondary cellular messengers, which are produced by cells as a result of direct activation.
This chapter does not consider systemic effects of low-power laser therapy.
CONTENTS:
48.1 Introduction ................
48.2 Clinical Applications and Effects of Light Coherence and Polarization...........
Coherence of Light • Coherence of Light Interaction with Biomolecules, Cells, and Tissues
48.3 Enhancement of Cellular Metabolism via Activation of Respiratory Chain: A Universal  Photobiological Action Mechanism ...........................................................
Cytochrome c Oxidase as the Photoacceptor in the Visible-to-Near-Infrared Spectral Range • Primary Reactions after Light Absorption • Cellular Signaling (Secondary Reactions) • Partial Derepression of Genome of Human Peripheral Lymphocytes: Biological Limitations of Low-Power Laser Effects
48.4 Enhancement of Cellular Metabolism via Activation of Nonmitochondrial Photoacceptors:
Indirect Activation/Suppression....................................
48.5 Conclusion......................................................................
Coherent properties of laser light are not manifested at the molecular level by light interaction with biotissue. The absorption of low-intensity laser light by biological systems is of a purely noncoherent (i.e., photobiological) nature. At the cellular level, biological responses are determined by absorption of light with photoacceptor molecules. Coherent properties of laser light are unimportant when the cellular monolayer, the thin layer of cell suspension, and the thin layer of tissue surface are irradiated. In these cases, the coherent and noncoherent light with the same wavelength, intensity, and dose provides the same biological response. Some additional
(therapeutic) effects from coherent and polarized radiation can occur only in deeper layers of bulk tissue.
Acknowledgments.....................................................................
References ..................................................................................
http://andreannarainville.com/pdf/Karu-2003.pdf

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