Low-level Laser Therapy Irradiation Research Articles

Photobiological modulation of hepatoma cell lines and hepatitis B subviral particles secretion in response to 650 nm low level laser treatment

BackgroundChronic hepatitis B virus (HBV) infection is a serious global health concern, with an increased incidence and risk of developing cirrhosis and hepatocellular carcinoma (HCC). Patients chronically infected with HBV are likely to experience chronic oxidative stress, leading to mitochondrial dysfunction. Photobiomodulation is induced by the absorption of low-level laser therapy (LLLT) with a red or infrared laser by cytochrome C oxidase enzyme, resulting in mitochondrial photoactivation. Although it is widely used in clinical practice, the use of LLL as adjuvant therapy for persistent HBV infection is uncommon. This study aimed to investigate the effect of LLLT dosage from 2 J/cm2 to 10 J/cm2 of red diode laser (650 nm) on both hepatoma cell lines (HepG2.2.15 [integrated HBV genome stable cell model] and non-integrated HepG2), with a subsequent impact on HBVsvp production.MethodsThe present study evaluated the effects of different fluences of low-level laser therapy (LLLT) irradiation on various aspects of hepatoma cell behavior, including morphology, viability, ultrastructure, and its impact on HBVsvp synthesis.ResultsIn response to LLLT irradiation, we observed a considerable reduction in viability, proliferation, and HBVsvp production in both hepatoma cell lines HepG2.2.15 and HepG2. Ultrastructural modification of mitochondria and nuclear membranes: This effect was dose, cell type, and time-dependent.ConclusionsThe use of LLLT may be a promising therapy for HCC and HBV patients by reducing cell proliferation, HBVsvp production, and altering mitochondrial and nuclear structure involved in cellular death inducers. Further research is required to explore its clinical application.

Advances in the Bioregulation of Mesenchymal Stem Cells by Low-Level Laser Therapy During Bone Formation: A Narrative Review

This article reviews the progress of research on the modulation of the biological effects of low-level laser therapy (LLLT) on Mesenchymal stem cells (MSC) and the influence of the basic LLLT parameters and irradiation scenarios. A thorough search of the literature in the PubMed, Web of Science and Embase databases, including articles published in peer-reviewed journals, was conducted to collect relevant information on LLLT and MSCs. A comprehensive search of PubMed, Web of Science, and Embase databases was performed using the keywords "Low level laser," "mesenchymal stem cells," " cell proliferation," and "osteogenic differentiation." The search was limited to studies published in English between 2009 and 2022, including in vitro and in vivo studies. LLLT has the potential to promote MSC proliferation and osteogenic differentiation, with significant applications in bone tissue engineering. Factors that influence the biological effects of LLLT on MSC include cell type, culture medium, duration of irradiation, the frequency of laser irradiation, irradiation spot size, and type of light flux distribution. The limitations of this review include heterogeneous experimental conditions and the inability to design experiments that consider all influencing factors simultaneously.

Assessment of the effect of low-level laser therapy (808nm) on the proliferation and migration of fibroblasts from chronic wound tissue

Objectives: 1/To evaluate the morphology and proliferation of cultured dermal fibroblasts derived from patients with chronic wounds. 2/Evaluating the effect of low-level laser therapy (LLLT) 808nm on the proliferation and migration of fibroblasts from chronic wound tissue. Subjects and Methods: A prospective study was conducted on 36 dermal samples from 12 patients with pressure ulcers and diabetic ulcers. Dermal samples were taken in the operating room and fibroblasts were isolated according to the procedure of Freshney RI (2003). Fibroblasts obtained in P3 generation will be cultured on 6 plates and divided into groups of laser irradiation with different energy levels and a control group (without laser). Conduct LLLT projection with energy levels of 5J; 4J; 3.5J; 3J; 2.5J and exposure times were: 60, 48, 42, 36, the 30s, respectively, for 3 consecutive days to evaluate proliferation and migration between the Laser group and the control group. Cells were counted at 24 h after the last laser exposure using the trypan blue experiment. Results: The wound base fibroblasts (position 1) proliferated slowly, showed signs of aging, did not retain their phenotype, died floating on the surface of the culture plate, and could not trypsin to the P4 generation. Fibroblasts at positions 2, and 3 (wound margins and healing skin adjacent to the wound) could be isolated to the P3, P4, and P5 generation and did not change morphology. After LLLT irradiation, the number of cells in the laser group with energy levels: 3.5J; 3J, and 2.5J increased higher than the control group; with the highest increase at the energy level of 3J. LLLT dose of 3J with a corresponding exposure time of 36s increased the migration rate of fibroblasts when compared with the control group, completely covering the culture plate on 3rd day.Conclusion: Fibroblasts derived from patients with pressure ulcers and diabetic ulcers can be isolated from the wound edge and healed skin adjacent to the wound without changing morphology when cultured. After LLLT irradiation (808 nm) on isolated fibroblasts, the effect was dose-dependent. The 3J dose did not change fibroblast morphology; or induce biostimulation, proliferation, and migration of cultured fibroblast samples derived from chronic wound patients.

Effects of low-level laser therapy and adipose-derived stem cells on the viability of autologous fat grafts: a preliminary study

Background Autologous fat grafts are commonly used in cosmetic and reconstructive surgery, and various methods are used to improve their viability. Low-level laser therapy (LLLT) can enhance the proliferation, growth, and differentiation of various cell lines, including stem cells. Our study investigated and compared the effects of LLLT and the addition of adipose-derived stem cells (ADSCs) on the viability of fat grafts.Methods Twenty nude mice were divided into four groups: control (group 1), LLLT irradiation (group 2), ADSC addition (group 3), and LLLT irradiation+ADSC addition (group 4). ADSCs were combined with the fat tissue. LLLT irradiation was performed once daily for 1 week from the day of grafting. After 8 weeks, the weight, volume, histology, and Western blot findings of the grafted fat tissues were evaluated.Results The retention rate and volume of the fat tissue in groups 2, 3, and 4 were higher than that of group 1, but the difference was not statistically significant. The number of capillaries, histological parameters, and immunofluorescence staining analyses for CD68, CD31, fibroblast growth factor, and vascular endothelial growth factor (VEGF) showed no significant differences among the four groups. The expression level of VEGF was higher in group 2 than in the other groups, but not to a statistically significant level.Conclusions LLLT and ADSCs did not significantly improve the viability of autologous fat grafts. Therefore, further study is necessary to develop safe and effective methods to improve the viability of these grafts for clinical application.

COMPARATIVE EVALUATION OF EFFECT OF IRRADIATION USING LOW- LEVEL LASER THERAPY WITH TWO DIFFERENT WAVELENGTHS ON STABILITY OF DENTAL IMPLANTS

Aim: This study aimed to compare the effect of low-level laser therapy irradiation with two different wavelengths after osteotomy site preparation on the stability of dental implants.
 Materials and Methods: The current study is a double-masked, randomized clinical trial. A total of seven patients of age 25 to 55 years were assigned randomly into two groups. Group I: Osteotomy site irradiated with low-level laser therapy of wavelength 940nm. GROUP II: Osteotomy site irradiated with low-level laser therapy of wavelength 660nm.
 Implant stability was measured after implant placement using the Penguin RFA device. Bone formation was assessed with Cone Beam Computed Tomography.
 Results: The current trial results showed that low-level laser therapy aided in bone formation around the implants, but there is no significant difference between the two different wavelengths.
 Conclusion: Implant stability increased in both groups, but no difference is observed among the groups. Hounsfield units indicating bone formation improved in both the groups with no pronounced difference between the groups. All 14 implants were stable, thus indicating that low-level laser therapy aids bone formation, but the wavelength difference had no significant impact.
 Keywords: Low level laser therapy, Implant Stability, Resonance frequency analysis

Effects of Low-level Laser Therapy on Fibroblast Density in Achilles Tendon Rupture Healing

Objective: To investigate the effect of low-level laser therapy (LLLT) on fibroblast proliferation as a part of the tendon healing cascade. Methods: This was an unpaired comparative experimental animal laboratory study with one control groups and two experimental groups, each consisted of 10 Sprague Dawley rats. The experimental groups 1 and 2 were given infrared irradiation for 15 minutes and 30 minutes per day, respectively, after having their achilles tendon partially cut. Histological assessment was carried out to assess the fibroblast density in healing site after three weeks on intervention. Results: The median values of fibroblast density in group 1, group 2, and control group were 1, 2, and 1, respectively, with a p-value of 0.014. No significant difference (p = 0.123) was identified on Mann-Whitney test between the fibroblast density of group 1 and group 2. The same was also true forgroup 1 and control group (p = 0.315). A significant difference was found between group 2 and control group (p = 0.005). Conclusions: A regime of LLLT irradiation of 30 min/day for two weeks (1080 J cm-2) improves the fibroblast proliferation amidst tendon healing in a partially injured achilles tendon in a rat model, which is not seen in the regime with a 15 min/day duration. This emphasizes the significance of irradiation time to improve tendon healing, despite the deficient understanding of the mechanism.

Effect of diode laser potentiality on proliferation of dental pulp stem cells (in vitro study)

BackgroundThe field of laser-based photochemical reactions receives a great promising for additional applications especially for targeting cells, pathogens, or molecules. Limited studies have investigated the impact of light-emitting diode on stem cell behavior. Thus, the aim of the present study was to assess the effect of diode laser irradiations on the proliferation of stem cells isolated from the human dental pulp. Isolation procedures were according to previously developed protocols for dental pulp stem cells (DPSCs). Low-level laser therapy irradiation (LLLT) was applied in two doses (0.5 J/cm2 and 1 J/cm2 for 20 s) into 96-well plates by the diode laser device (970 nm) through the fiber optic (SiroLaser fibers 320) at a distance from the opening of the wells to be accurate for equal distribution of the laser irradiation. To assess the proliferation capacity of the isolated stem cells, MTT assay was performed 24 h, 48 h, and 72 h.ResultsThere was no significant difference among the different groups (gp 1 control, gp II dose 0.5 J/cm2, gp III dose 1 J/cm2) on day 1. While on day 2, the optical density of DPSCs subjected to dose 1 was found to be significantly higher than that of those subjected to dose 2. This was also demonstrated on day 3. It was also demonstrated that the proliferation of DPSCs subjected to dose 1 increased compared to that of DPSCs subjected to dose 2 from day 1 to day 2. There was a significant decrease in the cell number in both groups by 72 h.ConclusionIn conclusion, the use of LLLT as a stimulatory factor for enhancing and proliferation of the stem cells is very promising.

INFLUENCE OF LOW-LEVEL LASER IRRADIATION ON ORTHODONTIC MOVEMENT AND PAIN LEVEL - A RANDOMIZED CLINICAL TRIAL

ABSTRACT Introduction The aim of this study was to analyse the orthodontic tooth movement rate and pain sensitivity during maxillary and mandibular canine retraction submitted to irradiation with low-level laser therapy (LLLT) in a monthly dose. Methods Eleven Class I malocclusion patients with extraction of the first maxillary and mandibular premolars were selected. Using a split-mouth, double-blind, placebo-controlled randomized design, LLLT irradiation was applied after canine initial retraction activation, performed with NiTi coil springs. Monthly, a couple of dental casts were obtained before laser application, which was subsequently scanned with the 3Shape Ortho System. The three-dimensional images were evaluated with Ortho Analyser software to measure the amount of movement of the retracted canines. The patients also used a visual analog scale after 12, 24, 48 and 72 hours of initial activation to assess pain sensitivity. Results There was only a significantly greater amount of retraction of the irradiated mandibular canines in the first month of laser application. There was no intergroup difference in pain sensitivity. Conclusion The LLLT application protocol showed only a statistically significant acceleration of tooth movement of the mandibular canines in the first month of application but did not produce any reduction in pain sensitivity.

Management of dry socket with low-level laser therapy.

The aim of this study is to investigate the efficacy of delivering low-level laser therapy (LLLT) in the management of dry socket at University Dental Hospital Sharjah. Forty-five patients with dry socket were divided into two treatment groups. Group I dry socket patients (n = 30) received conventional treatment while group II patients (n = 15) were irradiated with LLLT at a setting of 200-mW, 6-J, continuous-wave mode using an R02 tipless handpiece (Fotona Er:YAG, Europe), on the buccal, lingual, and middle surfaces of the socket for 30s from a delivery distance of 1cm. Pain score and quantification of granulation tissue in the socket were recorded at 0, 4, and 7days post-dry socket treatment. Results showed that the LLLT-irradiated group II sockets showed a much lower VAS pain score of 1-2 as early as day 4, and a richer amount of granulation tissue compared to the conventional treated group I socket. The amount and rate of granulation tissue formation in the dry socket are inversely proportional to the pain score showing significant clinical effectiveness of LLLT on promoting the healing of the dry socket, with improvement in symptoms (P = .001). Conventionally treated dry sockets take at least 7days to match the effective healing of an LLLT-irradiated dry socket. LLLT irradiation influences biomodulation of dry socket healing by dampening inflammation, promoting vascularization, stimulating granulation, and controlling pain symptoms. LLLT may be an additional effective tool for managing dry sockets in general dental practice.

Efficacy of low-level laser therapy on management of Bell's palsy: a systematic review.

The aim of this study is to evaluate the efficacy of low-level laser therapy (LLLT) in patients with Bell's palsy (BP) through a systematic review method. We systematically searched international databases including PubMed, Scopus, and Web of Science to find eligible articles without language limitation. All relevant randomized controlled trials (RCTs) that compared the efficacy of the LLLT with placebo laser, exercise, massage, or no intervention on BP patients were included. Four studies (out of 259) had met our inclusion criteria involving 171 patients and were entered to the systematic review. Full texts of the selected studies were retrieved and critically appraised using Physiotherapy Evidence Database (PEDro) scale. The patients of all trials were in sub-acute (less than 1week) stage. Both of LLLT and control groups showed significant improvement after trials. Two authors reported significant differences between the groups after 6weeks of laser application (830nm, 100mW). In converse, two other authors did not identify any effectiveness following 4weeks and 15days of LLLT application with 670 and 830nm wavelength, sequentially. There is clear lack of information lead to get and evidence-based suggestion for the LLLT application on Bells' palsy; however, the LLLT irradiation with 830nm and 100mW power for a period of 6weeks might be beneficial on recovery for the patients with sub-acute Bell's palsy. There were no reported adverse effects during treatment and/or follow-up sessions.

PROTECTIVE EFFECT OF LOW LEVEL LASER THERAPY ON DORSAL SKIN FLAPS SURVIVAL: RELEVANCE TO CYTOKINES SECRETION.

The loss of skin flaps (SF) due to tissue necrosis can be catastrophic, even with mortality, especially when there is exposure of large vessels or noble structures. This outcome occurs between 2 to 20% of the procedures performed. There is no currently adjuvant treatment that improves the survival of cutaneous flaps, without side effects or significant risks. Recent studies have sought to prove the efficiency of photobiomodulation (PBM) by means of Low Level Laser Therapy (LLLT) and present promising results for increased SF survival.OBJECTIVETo evaluate the effect of LLLT in dorsal skin flaps of mice in terms of tissue necrosis extent as well as biochemical analysis of pro and anti‐inflammatory cytokines.METHODSForty‐eighth Balb/C (20–25 g) male mice were randomly distributed into two groups with twenty‐four animals each; (1) control group that was not submitted to laser irradiation and (2) experimental group that was submitted to laser irradiation on the flap pedicle with a 660 nm wavelength, exposure radiant of 2.25 J/cm2 for a total time of 20 s/point. The treatment started immediately after performing the cranial base random skin flap (3× 1 cm dimension). The animals were euthanized after the evaluation of the percentage of necrosis area, blood and skin tissue was collected for analysis of cytokines and histology on 4th, 7th and 10th postoperative days. Results demonstrated that LLLT irradiation reduced the area of necrosis, significantly decreased IL‐1, IL‐6 and TNF‐α and increased IL‐10 cytokines compared to the non‐irradiated control group. In conclusion, LLLT may improve the healing of skin flaps by decreasing pro‐inflammatory cytokines and increasing the anti‐inflammatory IL‐10.Serum Interleukines after low level laser therapy (gray) versus control group (black). Significant decrease in pro‐inflamatories interleukines 1, 6 and tumor necrosis factor alfa and significant increase in anti‐inflamatory interleukin 10 after 4, 7 and 10 days post‐op.Figure 1

To Evaluate the Efficacy of 780 nm Low Level Laser Therapy for the Treatment of Plantar Fasciitis in South Western Ethiopia

Objective: By definition plantar fasciitis (PF)is an inflammation of the plantar fascia. Present study evaluates the effects of 780 nm Low Level Laser Therapy (LLLT)in the treatment of plantarfasciitis &establishes the status of LLLT as a cost effective modality for the treatment of plantar fasciitis. Method: 80 subjects were selected on the basis of the inclusion and exclusion criteria andwere recruited randomly to either 780nm LLLT (experimental group) or sham irradiation (placebo control group). Result: Overall results showed significant difference in Visual Analogue Scale (VAS), Foot Function Index (FFI) andDorsiflexion (DF) from 0 week to 4th week inGroup A indicating that the rate of improvement in Group A was more than Group B. Hence concluding the positive contribution of therapeutic modality for pain relief, increasing functional ability and increasing dorsiflexion Range of Motion(ROM) Conclusion: The present study finds that LLLT at the parameters shown is a safe, potent and cost effective conservative treatment method for the patients having plantar fasciitis.

Low-Level Laser Therapy Stimulates Proliferation in Head and Neck Squamous Cell Carcinoma Cells.

Objectives: Low-level laser therapy (LLLT) is a promising non-invasive treatment option for oropharyngeal mucositis, which is a common side effect of many oncological treatments. LLLT is known for its wound healing properties due to the stimulation of cellular processes, such as proliferation, migration and differentiation. Controversy exists on the possible stimulatory effect of LLLT on head and neck cancer (HNSCC) cells in patients treated with radiotherapy. The aim of this study was to evaluate the biostimulatory effect together with the underlying mechanisms of LLLT on HNSCC cancer cells and normal epithelial cells.Materials and methods: HNSCC cell lines (SCC154, SQD9, and SCC61) and human tonsil epithelial cells were exposed to a Gallium-Aluminum-Arsenide diode laser (830 nm, 150 mW) with energy densities of 0, 1, and 2 J/cm2. The proliferation potential of the cells was assessed by Sulforhodamine B assay, immunoblotting (mitogenic pathways), immunocytochemistry (Ki67), and flow cytometry (PI cell cycle staining).Results: Cell proliferation was increased in HNSCC cell lines after laser irradiation with 1 J/cm2, whereas no significant increase was seen after laser irradiation with 2 J/cm2. In contrast, no effect on cell proliferation was seen in the human tonsil epithelial cells after laser irradiation with any of the energy densities. The increased proliferation was associated with elevated levels of pAKT, pERK, and Ki67 protein expression and cell cycle progression.Conclusion: Our results show that LLLT increases cell proliferation in a dose-dependent manner in HNSCC cells but not in normal epithelial tonsil cells. These results suggest that LLLT has to be used with caution when treating oropharyngeal mucositis in HNSCC patients since tumor cells present in the LLLT irradiation field could be triggered by LLLT.

Determination of Optimum Operation Parameters for Low-Intensity Pulsed Ultrasound and Low-Level Laser Based Treatment to Induce Proliferation of Osteoblast and Fibroblast Cells

The aim of this study was to determine the optimum operating parameters (pulse duration, energy levels, and application time) to promote induction of osteoblast and fibroblast cell proliferation and to maintain cell viability treated with low-intensity pulsed ultrasound (LIPUS) and low-level laser therapy (LLLT). The positive effects of LIPUS and LLLT on cellular activity have been reported in recent years. Comparisons between experimental parameters of previous studies are difficult because scientific studies reported frequencies and the duty cycles of LIPUS and wavelengths and doses of LLLT in a wide range of parameters. However, optimum amount of energy and optimum time exposure must be determined to induce bone and tissue cell proliferation for effective healing process and to avoid cell damage. Fibroblast and osteoblast cell cultures were irradiated with LIPUS (10-50% pulse and continuous mode at 1 and 3 MHz for 1, 3, and 5 min) and LLLT (4, 8, and 16 J at 50, 100, 200, 300, 400, and 500 mW). Cell cultures were analyzed using XTT assay. For both cell types, LIPUS treatment with 10% pulse (1:9 duty cycle), 3 MHz, and for 1 min and LLLT treatment over 100 mV for 4, 8, and 16 J modalities contributed to the growth, and may help bone repair and tissue healing process optimally. Bio-stimulating effects of LLLT irradiation promote proliferation and maintain cell viability better than LIPUS treatment without causing thermal response for both cell types, and the therapeutic modality above 200 mV has maximum effectiveness.

A Comparative Evaluation of Interleukin 1 Beta and Prostaglandin E2 with and without Low-level Laser Therapy during En masse Retraction.

Background and Objectives:Orthodontic forces are known to produce mechanical damage and inflammatory mediators such as prostaglandins (PGs) and interleukin (IL)-1, in the periodontium and dental pulp. Low-level laser therapy (LLLT) is a stimulator of the on-going biological process in tissue and found to be effective in modulating cell activity, which is involved in orthodontic tooth movement. Here, a humble effort has been made to study two such cytokines, namely IL-1 β and PG E2 (PGE2) which are partially responsible for bone turnover. The purpose of this study was to compare the changes occurring in the values of IL-1 β and PGE2 in the gingival crevicular fluid (GCF) during en masse retraction with and without LLLT.Methodology:GCF was collected using micropipettes from the distal ends of upper canines. The experimental side was exposed to biostimulation using 810 nm gallium-aluminum-arsenide diode laser and the contralateral side taken as control. A total of 10 irradiations for 10 s per site were given, five on the buccal side and five on the palatal side, to cover the entire periodontal fibers and the alveolar process around the tooth. After 7 days and 21 days of retraction, GCF sample was collected. Quantitative analysis of IL-1 β and PGE2 in the GCF samples was assessed using a commercially available Raybiotech® IL-1 β and Human PGE2.Results:(1) IL-1 β and PGE2 levels showed significant results from baseline to 21 days after LLLT irradiation. (2) LLLT-assisted retraction was significantly faster than conventional retraction.Interpretation and Conclusion:It was concluded from the study that IL-1 β and PGE2 levels peaked after LLLT. The difference in the levels of both cytokines was statistically significant.

Exploring the effects of low-level laser therapy on fibroblasts and tumor cells following gamma radiation exposure.

Ionizing radiation (IR) induces DNA damage and low-level laser therapy (LLLT) has been investigated to prevent or repair detrimental outcomes resulting from IR exposure. Few in vitro studies, however, explore the biological mechanisms underlying those LLLT benefits. Thus, in this work, fibroblasts and tumor cells are submitted to IR with doses of 2.5Gy and 10Gy. After twenty-four-h, the cells are exposed to LLLT with fluences of 30Jcm-2 , 90Jcm-2 , and 150Jcm-2 . Cellular viability, cell cycle phases, cell proliferation index and senescence are evaluated on days 1 and 4 after LLLT irradiation. For fibroblasts, LLLT promotes - in a fluence-dependent manner - increments in cell viability and proliferation, while a reduction in the senescence was observed. Regarding tumor cells, no influences of LLLT on cell viability are noticed. Whereas LLLT enhances cell populations in S and G2 /M cell cycle phases for both cellular lines, a decrease in proliferation and increase in senescence was verified only for tumor cells. Putting together, the results suggest that fibroblasts and tumor cells present different responses to LLLT following exposure to gamma-radiation, and these promising results should stimulate further investigations. Senescence of tumor cells and fibroblasts on the 4th day after ionizing radiation (IR) and low-level laser therapy (LLLT) exposures. The number of senescent cells increased significantly for tumor cells (a) while for fibroblasts no increment was observed (b). The blue collor indicates senescence activity.

Effect of the transdermal low-level laser therapy on endothelial function

The effect of low-level laser therapy (LLLT) on the cardiovascular system is not fully established. Since the endothelium is an important endocrine element, establishing the mechanisms of LLLT action is an important issue.The aim of the study was to evaluate the effect of transdermal LLLT on endothelial function.In this study, healthy volunteers (n = 40, age = 20–40 years) were enrolled. N = 30 (14 female, 16 male, mean age 30 ± 5 years) constituted the laser-irradiated group (LG). The remaining 10 subjects (6 women, 4 men, mean age 28 ± 5 years) constituted the control group (CG). Participants were subjected to LLLT once a day for three consecutive days. Blood for biochemical assessments was drawn before the first irradiation and 24 h after the last session. In the LG, transdermal illumination of radial artery was conducted (a semiconductor laser λ = 808 nm, irradiation 50 mW, energy density 1.6 W/cm2 and a dose 20 J/day, a total dose of 60 J). Biochemical parameters (reflecting angiogenesis: vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF), angiostatin; antioxidative status: glutathione (GSH) and the nitric oxide metabolic pathway: symmetric dimethylarginine (SDMA), asymmetric dimethylarginine (ADMA) and l-arginine) were assessed. In the LG, a significant increase in GSH levels and considerable decrease in angiostatin concentration following the LLLT were observed. No significant differences in levels of the VEGF, FGF, SDMA, ADMA were observed.LLLT modifies vascular endothelial function by increasing its antioxidant and angiogenic potential. We found no significant differences in levels of the nitric oxide pathway metabolites within 24 h following the LLLT irradiation.

Acute effects of low-level laser therapy irradiation on blood lactate and muscle fatigue perception in hospitalized patients with heart failure-a pilot study.

The objective of the present study is to evaluate the acute effects of low-level laser therapy (LLLT) on functional capacity, perceived exertion, and blood lactate in hospitalized patients with heart failure (HF). Patients diagnosed with systolic HF (left ventricular ejection fraction <45%) were randomized and allocated prospectively into two groups: placebo LLLT group (n = 10)-subjects who were submitted to placebo laser and active LLLT group (n = 10)-subjects who were submitted to active laser. The 6-min walk test (6MWT) was performed, and blood lactate was determined at rest (before LLLT application and 6MWT), immediately after the exercise test (time 0) and recovery (3, 6, and 30min). A multi-diode LLLT cluster probe (DMC, São Carlos, Brazil) was used. Both groups increased 6MWT distance after active or placebo LLLT application compared to baseline values (p = 0.03 and p = 0.01, respectively); however, no difference was observed during intergroup comparison. The active LLLT group showed a significant reduction in the perceived exertion Borg (PEB) scale compared to the placebo LLLT group (p = 0.006). In addition, the group that received active LLLT showed no statistically significant difference for the blood lactate level through the times analyzed. The placebo LLLT group demonstrated a significant increase in blood lactate between the rest and recovery phase (p < 0.05). Acute effects of LLLT irradiation on skeletal musculature were not able to improve the functional capacity of hospitalized patients with HF, although it may favorably modulate blood lactate metabolism and reduce perceived muscle fatigue.

Bisphosphonate-related osteonecrosis of the jaw: a review of the potential efficacy of low-level laser therapy.

Osteonecrosis of the jaw (ONJ) resulting from administration of bisphosphonates (BP) or denosumab is a rare but severe complication in cancer patients. Complete remission depends on the stage of ONJ; it can be estimated in the range of 20-30%. Low-level laser therapy (LLLT) is a logical additional option, as it has been recognized effective for the management of chemotherapy and/or radiotherapy-induced mucositis. LLLT irradiation has anti-inflammatory actions and thus can help to control pain, as well as biostimulating properties with favorable actions on bacterial control and wound healing. We review the results of seven published studies of LLLT in BP-associated ONJ. LLLT results in an overall response rate of 55% superior to that observed in controls (30%). Our review suggests that there might be an advantage to add LLLT to the "classical" management of ONJ. This therapy is easy to administer and is not associated with any known side effects. Further research is needed to remove any doubt of protection or enhancement of carcinogenic processes. We believe that prospective well-controlled studies of LLLT in ONJ are warranted. If the positive results are confirmed, it would represent a great improvement for the quality of life of many patients.

Study on the selection of laser wavelengths in the intravascular low-level laser irradiation therapy.

According to the absorption spectra of blood and hemoglobin, a photon-bond energy formula is established using physical methods and the effects on hemoglobin of low-level laser at different wavelengths are analyzed. The results show that lasers with the peak wavelengths of 200∼240, 275, and 342 nm in the whole blood absorption spectra curve are easy to destroy protein molecules and then lead to hemoglobin lose biological activity. While lasers with wavelengths longer than 800 nm will reduce the oxygen carrying capacity of blood, only lasers with wavelengths between 630 and 670 nm have the best efficacy.