123 Application of Biological Feedback Systems and Other Methods of Examinations for Control of Effects of Light Therapy (original) (raw)
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Mechanisms of low level light therapy – an introduction
2006
The use of low levels of visible or near infrared light for reducing pain, inflammation and edema, promoting healing of wounds, deeper tissues and nerves, and preventing tissue damage has been known for almost forty years since the invention of lasers. Originally thought to be a peculiar property of laser light (soft or cold lasers), the subject has now broadened to include photobiomodulation and photobiostimulation using non-coherent light. Despite many reports of positive findings from experiments conducted in vitro, in animal models and in randomized controlled clinical trials, LLLT remains controversial. This likely is due to two main reasons; firstly the biochemical mechanisms underlying the positive effects are incompletely understood, and secondly the complexity of rationally choosing amongst a large number of illumination parameters such as wavelength, fluence, power density, pulse structure and treatment timing has led to the publication of a number of negative studies as well as many positive ones. In particular a biphasic dose response has been frequently observed where low levels of light have a much better effect than higher levels. This introductory review will cover some of the proposed cellular chromophores responsible for the effect of visible light on mammalian cells, including cytochrome c oxidase (with absorption peaks in the near infrared) and photoactive porphyrins. Mitochondria are thought to be a likely site for the initial effects of light, leading to increased ATP production, modulation of reactive oxygen species and induction of transcription factors. These effects in turn lead to increased cell proliferation and migration (particularly by fibroblasts), modulation in levels of cytokines, growth factors and inflammatory mediators, and increased tissue oxygenation. The results of these biochemical and cellular changes in animals and patients include such benefits as increased healing in chronic wounds, improvements in sports injuries and carpal tunnel syndrome, pain reduction in arthritis and neuropathies, and amelioration of damage after heart attacks, stroke, nerve injury and retinal toxicity.
Biological effects of low level laser therapy
Journal of lasers in medical sciences, 2014
The use of low level laser to reduce pain, inflammation and edema, to promote wound, deeper tissues and nerves healing, and to prevent tissue damage has been known for almost forty years since the invention of lasers. This review will cover some of the proposed cellular mechanisms responsible for the effect of visible light on mammalian cells, including cytochrome c oxidase (with absorption peaks in the Near Infrared (NIR)). Mitochondria are thought to be a likely site for the initial effects of light, leading to increased ATP production, modulation of reactive oxygen species, and induction of transcription factors. These effects in turn lead to increased cell proliferation and migration (particularly by fibroblasts).
LASER THERAPY, 2005
best only partly understood is the athermal reaction which accompanies with very few exceptions all photothermal reactions associated with the surgical laser. One particular field where this athermal reaction plays a role at least as important as the thermal reactions is in the application of nonablative light sources in the rejuvenation of photoaged skin. This field is expanding rapidly, but the photobiology behind the processes by which a particular type and dose of light can repair damage (which was actually also caused in the first place by light) is imperfectly understood. Although the main concept of nonablative skin rejuvenation is centred on the creation of a controlled zone of delivered thermal damage (DTD) in the upper dermis under a cooled epidermis, the incident light energy, in the form of photons, does not simply stop at the DTD zone but continues on into the surrounding dermal tissue, mediating athermal photoreactions in the periphery of that thermal effect. These athermal reactions, at a cellular and subcellular level, contribute a great deal to the modulation of the wound healing process instigated by the DTD to produce the final hoped-for results. This article examines the range of athermal photoreactions which occur simultaneously with the thermally-mediated effects in nonablative skin rejuvenation, to a great extent in laser ablative resurfacing and indeed in any surgical application of the laser, and attempts to show the importance of these photobioreactions in achieving good clinical results. This first part of the series may well appear as 'old hat' to experienced users of lasers and light sources, but we feel it is important to start from the basics, rather than having to return to them to try and discover why tissue has failed to react to the incident light in the expected manner, and a possibly unhappy patient as a result. A thorough understanding of the basic properties of light and its parameters is extremely important when trying to appreciate the complexities of light-tissue interaction. Without this understanding, moreover, no-one should be using any form of light source on patients.
Photomedicine and Laser Surgery
Photomedicine and laser surgery
Objective: Visible light irradiations at doses of 5 and 12 J/cm 2 were applied to carp buffy coat leukocytes. Materials and Methods: The leukocytes response was measured by a chemiluminescence (CL) assay as basal (spontaneous) bCL and Ca ionophore-induced stimulated CL (StCL). Results: The irradiation caused a significant decrease in bCL in six out of 14 fish (susceptible fish) and rendered eight out of 14 fish unsusceptible. An inhibitory effect of light intensity dependence was more pronounced at 12 J/cm 2 . Furthermore, this inhibitory effect of irradiation on bCL was found in fish which displayed higher (433 ± 90 cpm/mL) pre-irradiation bCL, compared to unsusceptible subjects (88 ± 30 cpm/mL, p < 0.05). Similar differences in the intensity of preirradiation StCL were found between these fish groups (13,053 ± 5086 as compared to 1077 ± 294, p = 0.03). Moreover, the time-to-peak of StCL was significantly shorter in susceptible fish, indicating their hyperreactivity. Conclusion: These data show the inhibitory effect of visible light irradiation on blood leukocyte CL response in fish. These results suggest the prevention of host hyper-response which may occur under natural conditions of fish life. An Electron Paramagnetic Resonance (EPR) study of illuminated carp blood cells reveals the formation of Ascorbate free radicals (AFR) that may explain the decrease in reactive oxygen species (ROS) concentration following irradiation. 265
The Nuts and Bolts of Low-level Laser (Light) Therapy
Annals of Biomedical Engineering, 2012
Soon after the discovery of lasers in the 1960s it was realized that laser therapy had the potential to improve wound healing and reduce pain, inflammation and swelling. In recent years the field sometimes known as photobiomodulation has broadened to include light-emitting diodes and other light sources, and the range of wavelengths used now includes many in the red and near infrared. The term ''low level laser therapy'' or LLLT has become widely recognized and implies the existence of the biphasic dose response or the Arndt-Schulz curve. This review will cover the mechanisms of action of LLLT at a cellular and at a tissular level and will summarize the various light sources and principles of dosimetry that are employed in clinical practice. The range of diseases, injuries, and conditions that can be benefited by LLLT will be summarized with an emphasis on those that have reported randomized controlled clinical trials. Serious life-threatening diseases such as stroke, heart attack, spinal cord injury, and traumatic brain injury may soon be amenable to LLLT therapy.
Effect of pulsing in low-level light therapy
Lasers in surgery and medicine, 2010
Low level light (or laser) therapy (LLLT) is a rapidly growing modality used in physical therapy, chiropractic, sports medicine and increasingly in mainstream medicine. LLLT is used to increase wound healing and tissue regeneration, to relieve pain and inflammation, to prevent tissue death, to mitigate degeneration in many neurological indications. While some agreement has emerged on the best wavelengths of light and a range of acceptable dosages to be used (irradiance and fluence), there is no agreement on whether continuous wave or pulsed light is best and on what factors govern the pulse parameters to be chosen. The published peer-reviewed literature was reviewed between 1970 and 2010. The basic molecular and cellular mechanisms of LLLT are discussed. The type of pulsed light sources available and the parameters that govern their pulse structure are outlined. Studies that have compared continuous wave and pulsed light in both animals and patients are reviewed. Frequencies used in...
After the discovery of laser therapy it was realized it has useful application of wound healing and reduce pain, but due to the poor understanding of the mechanism and dose response this technique remained to be controversial for therapeutic applications. In order to understand the working and effectiveness different experiments were performed to determine the laser beam effect at the cellular and tissue level. This article discusses the mechanism of beam interaction at tissues and cellular level with different light sources and dosimetry principles for clinical application of low level laser therapy. Different application techniques and methods currently in use for clinical treatment has also been reviewed.