BACKGROUND AND OBJECTIVE: 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.
STUDY DESIGN/MATERIALS AND METHODS: The published peer-reviewed literature was reviewed between 1970 and 2010.
RESULTS: 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 other pulsed modalities used in physical therapy and biomedicine are compared to those used in LLLT.
CONCLUSION: There is some evidence that pulsed light does have effects that are different from those of continuous wave light. However further work is needed to define these effects for different disease conditions and pulse structures.
Near-infrared light therapy is an emerging neurostimulation technology, but its cellular mechanism of action remains unresolved. Using standard intracellular recording techniques, we observed that 5-10 ms pulses of 1889 nm light depolarized the membrane potential for hundreds of milliseconds in more than 85% of dorsal root ganglion and nodose ganglion neurons tested. The laser-evoked depolarizations (LEDs) exhibited complex, multiphasic kinetics comprising fast and slow components. There was no discernable difference in the LEDs in intact ganglion neurons and in acutely isolated neurons. Thus, the LED sensor seems to reside within the neuronal membrane. The near-uniform distribution of responsive neurons increased membrane conductance, and the negative reversal potential value (-41+/-2.9 mV) suggests that LED is unrelated to the activation of heat-sensitive transient receptor potential cation channel subfamily V member 1 channels. The long duration of LEDs favors an involvement of second messengers.
Astrocytes have been identified to actively contribute to brain functions through Ca(2+) signaling, serving as a bridge to communicate with neurons and other brain cells. However, conventional stimulation techniques are hard to apply to delicate investigations on astrocytes. Our group previously reported photostimulation with a femtosecond laser to evoke astrocytic calcium (Ca(2+)) waves, providing a noninvasive and efficient approach with highly precise targeting. In this work, detailed characteristics of astrocytic Ca(2+) signaling induced by photostimulation are presented. In a purified astrocytic culture, after the illumination of a femtosecond laser onto one cell, a Ca(2+) wave throughout the network with reduced speed is induced, and intracellular Ca(2+) oscillations are observed. The intercellular propagation is pharmacologically confirmed to be mainly mediated by ATP through P(2)Y receptors. Different patterns of Ca(2+) elevations with increased amplitude in the stimulated astrocyte are discovered by varying the femtosecond laser power, which is correspondingly followed by broader intercellular waves. These indicate that the strength of photogenerated Ca(2+) signaling in astrocytes has a positive relationship with the stimulating laser power. Therefore, distinct Ca(2+) signaling is feasibly available for specific studies on astrocytes by employing precisely controlled photostimulation.
Studies suggest that high-intensity physical exercise can cause damage to skeletal muscles, resulting in muscle soreness, fatigue, inflammatory processes and cell apoptosis. The aim of this study was to investigate the effects of low-level laser therapy (LLLT) on a decrease in creatine kinase (CK) levels and cell apoptosis. Twenty male Wistar rats were randomly divided into two equal groups: group 1 (control), resistance swimming; group 2 (LLLT), resistance swimming with LLLT. They were subjected to a single application of indium gallium aluminum phosphide (InGaAlP) laser immediately following the exercise for 40 s at an output power of 100 mW, wavelength 660 nm and 133.3 J/cm(2). The groups were subdivided according to sample collection time: 24 h and 48 h. CK was measured before and both 24 h and 48 h after the test. Samples of the gastrocnemius muscle were processed to determine the presence of apoptosis using terminal deoxynucleotidyl transferase (TdT)-mediated deoxyuridine triphosphate (dUTP) nick end labeling. (There was a significant difference in CK levels between groups (P < 0.0001) as well as between the 24 h and 48 h levels in the control group, whereas there was no significant intra-group difference in the LLLT group at the same evaluation times. In the LLLT group there were 66.3 +/- 13.2 apoptotic cells after 24 h and 39.0 +/- 6.8 apoptotic cells after 48 h. The results suggest that LLLT influences the metabolic profile of animals subjected to fatigue by lowering serum levels of CK. This demonstrates that LLLT can act as a preventive tool against cell apoptosis experienced during high-intensity physical exercise.
Studies covered 168 personal computer users, 98 jewelry female polishers, 64 assemblers of metallic ship frameworks. Various doses of laser rays in accordance with work conditions appeared effective for improving upper limbs microcirculation. The suggested method is based on effects of low-intensity laser irradiation.
To the Editor: Despite numerous cases of intractable hiccups, remarkably little is known about its cause and its treatment. Various therapeutic approaches, mostly pharmacological or invasive, have been reported for the treatment of chronic hiccups (1, 2, 3, 4, 5, 6, 7). Nevertheless, there has been no standard management in the treatment of persistent hiccups so far.
I report on a successful nonpharmacological treatment of chronic hiccups using Korean hand acupuncture. Korean hand acupuncture is a special form of acupuncture described by Dr. Yoo (8). A 70-yr-old patient with known coronary heart disease, reflux esophagitis, and hiatal hernia suffered from uncontrollable hiccups for 3 months. One month after the hiccups first occurred, the patient was diagnosed as having a central bronchial carcinoma, and 2 months later a pneumonectomy was performed. When we examined the patient, he was hiccuping continuously throughout the day. Conventional therapy of hiccups performed by the surgeons with chlorpromazine and metoclopramide was unsuccessful. Subsequently we started treatment with Korean hand acupuncture. Acupuncture was performed on both hands at the acupuncture points K-F3 and K-A12. K-F3 is an acupuncture point especially effective for the diaphragm, whereas K-A12 is for basic treatment of gastric disorders. Acupuncture was performed once a day on 5 consecutive days. On the first 2 treatment days, special hand acupuncture needles (0.7 mm in diameter, 15 mm in length) were inserted with a special applicator and were left in place for 30 min. After the needles were extracted, in each acupuncture session, continuous acupressure was applied to point K-F3 for 24 h. This was done with special discs having six raised dots each. The acupressure discs were fixed with an adhesive strip. In the first 24 h after commencement of acupuncture, the intensity and frequency of hiccups diminished; hiccups ceased completely after the second acupuncture treatment. During the next 3 days, prophylactic acupuncture was administered to the above-mentioned points using a low power diode laser (Helbo-Minilaser 2010 F: output 10 mW, wavelength 670 nm). Laser acupuncture was performed once a day for 60 s/point. Acupressure discs were also applied to point K-F3 for 24 h after each laser acupuncture treatment. Therapy was terminated after 5 days. No further hiccups occurred thereafter.
Three months after this treatment with Korean hand acupuncture, a gastroscopic examination was performed. Immediately after gastroscopy the hiccups appeared again. Two weeks later the patient contacted us again and we had two further sessions of Korean hand acupuncture on two consecutive days. Immediately after the first session the hiccups diminished, and after the second session the hiccups stopped completely. Twelve months have passed since then, and no further hiccups have appeared.
In contrast to pharmacological and invasive treatment of chronic hiccups, no side effects are known for Korean hand acupuncture. Because of the lack of side effects and its simplicity, Korean hand acupuncture should be the treatment of choice for chronic hiccups before applying other methods.
Photobiomodulation by light in the red to near infrared range (630â€“1000 nm) using low energy lasers or light-emitting diode (LED) arrays has been shown to accelerate wound healing, improve recovery from ischemic injury in the heart and attenuate degeneration in the injured optic nerve. Recent evidence indicates that the therapeutic effects of red to near infrared light result, in part, from intracellular signaling mechanisms triggered by the interaction of NIR light with the mitochondrial photoacceptor molecule cytochrome c oxidase. We have demonstrated that NIR-LED photo-irradiation increases the production of cytochrome oxidase in cultured primary neurons and reverses the reduction of cytochrome oxidase activity produced by metabolic inhibitors. We have also shown that NIR-LED treatment prevents the development of oral mucositis in pediatric bone marrow transplant patients. Photobiomodulation improves wound healing in genetically diabetic mice by upregulating genes important in the promotion of wound healing. More recent studies have provided evidence for the therapeutic benefit of NIRLED treatment in the survival and functional recovery of the retina and optic nerve in vivo after acute injury by the mitochondrial toxin, formic acid generated in the course of methanol intoxication. Gene discovery studies conducted using microarray technology documented a significant upregulation of gene expression in pathways involved in mitochondrial energy production and antioxidant cellular protection. These findings provide a link between the actions of red to near infrared light on mitochondrial oxidative metabolism in vitro and cell injury in vivo. Based on these findings and the strong evidence that mitochondrial dysfunction is involved in the pathogenesis of numerous diseases processes, we propose that NIR-LED photobiomodulation represents an innovative and non-invasive therapeutic approach for the treatment of tissue injury and disease processes in which mitochondrial dysfunction is postulated to play a role including diabetic retinopathy, age-related macular degeneration, Leberâ's hereditary optic neuropathy and Parkinsonâ's disease.
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 cell death and tissue damage has been known for over forty years since the invention of lasers. Despite many reports of positive findings from experiments conducted in vitro, in animal models and in randomized controlled clinical trials, LLLT remains controversial in mainstream medicine. The biochemical mechanisms underlying the positive effects are incompletely understood, and 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. A biphasic dose response has been frequently observed where low levels of light have a much better effect on stimulating and repairing tissues than higher levels of light. The so-called Arndt-Schulz curve is frequently used to describe this biphasic dose response. This review will cover the molecular and cellular mechanisms in LLLT, and describe some of our recent results in vitro and in vivo that provide scientific explanations for this biphasic dose response.