The Effects of a 785-nm AlGaInP Laser on the Regeneration of Rat Anterior Tibialis Muscle After Surgically-Induced Injury

Objective: This study aims to investigate the effects of low-level laser therapy (LLLT) on muscle regeneration. For this purpose, the anterior tibialis muscle of 48 male Wistar rats received AlGaInP laser treatment (785 nm) after surgically-induced injury.Background Data: Few studies have been conducted on the effects of LLLT on muscle regeneration at different irradiation doses.Materials and Methods: The animals were randomized into four groups: uninjured rats (UN); uninjured and laser-irradiated rats (ULI); injured rats (IN); and injured and laser-irradiated rats (ILI). The direct contact laser treatment was started 24 h after surgery. An AlGaInP diode laser emitting 75 mW of continuous power at 785 nm was used for irradiation. The laser probe was placed at three treatment points to deliver 0.9 J per point, for a total dose of 2.7 J per treatment session. The animals were euthanized after treatment sessions 1, 2, and 4. Mounted sections were stained with hematoxylin and eosin and used for quantitative morphological analysis, in which the number of leukocytes and fibroblasts were counted over an area of 4480 mu m(2). The data were statistically analyzed by analysis of variance (ANOVA) and the Bonferroni t-test.Results: Quantitative data showed that the number of both polymorphonuclear and mononuclear leukocytes in the inflammatory infiltrate at the injury site was smaller in the ILI(1), ILI(2), and ILI(4) subgroups compared with their respective control subgroups (IN(1), IN(2), and IN(4)) for sessions 1, 2, and 4, respectively (p < 0.05). on the other hand, the number of fibroblasts increased after the fourth treatment session (p < 0.05). With regard to the regeneration of muscle fibers following injury, only after the fourth treatment session was it possible to find muscle precursor cells such as myoblasts and some myotubes in the ILI(4) subgroup.Conclusion: During the acute inflammatory phase, the AlGaInP laser treatment was found to have anti-inflammatory effects, reducing the number of leukocytes at the injury site and accelerating the regeneration of connective tissue.

Effect of GaAlAs Laser Irradiation on the Epiphyseal Cartilage of Rats

Objective: To study the effect of an 830-nm gallium-aluminum-arsenic (GaAlAs) diode laser at two different energy densities (5 and 15 J/cm(2)) on the epiphyseal cartilage of rats by evaluating bone length and the number of chondrocytes and thickness of each zone of the epiphyseal cartilage. Background Data: Few studies have been conducted on the effects of low-level laser therapy on the epiphyseal cartilage at different irradiation doses. Materials and Methods: A total of 30 male Wistar rats with 23 days of age and weighing 90 g on average were randomly divided into 3 groups: control group (CG, no stimulation), G5 group (energy density, 5 J/cm(2)), and G15 group (energy density, 15 J/cm(2)). Laser treatment sessions were administered every other day for a total of 10 sessions. The animals were killed 24 h after the last treatment session. Histological slides of the epiphyseal cartilage were stained with hematoxylin-eosin (HE), photographed with a Zeiss photomicroscope, and subjected to histometric and histological analyses. Statistical analysis was performed using one-way analysis of variance followed by Tukey's post hoc test. All statistical tests were performed at a significance level of 0.05. Results: Histological analysis and x-ray radiographs revealed an increase in thickness of the epiphyseal cartilage and in the number of chondrocytes in the G5 and G15 groups. Conclusion: The 830-nm GaAlAs diode laser, within the parameters used in this study, induced changes in the thickness of the epiphyseal cartilage and increased the number of chondrocytes, but this was not sufficient to induce changes in bone length.

Comparison of the photodynamic fungicidal efficacy of methylene blue, toluidine blue, malachite green and low-power laser irradiation alone against Candida albicans

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Anti-Inflammatory Effects of Low-Level Light Emitting Diode Therapy on Achilles Tendinitis in Rats

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Low power laser radiation at 685 nm stimulates stem-cell proliferation rate in Dugesia tigrina during regeneration

Today's scientific interest in tissue engineering for organ transplantations and regeneration from stem cells, allied with recent observations on biostimulation of tissues and cells by laser radiation, stands as a strong motivation for the present work, in which we examine the effects of the low power laser radiation onto planarians under regenerative process. To investigate those effects, a number of 60 amputated worms were divided in three study groups: a control group and two other groups submitted to daily 1 and 3 min long laser treatment sections at similar to 910 W/m(2) power density. A 685 nm diode laser with 35 mW optical power was used. Samples were sent to histological analysis at the 4th, the 7th and the 15th (lays after amputation. A remarkable increase in stem cells counts for the fourth day of regeneration was observed when the regenerating worms was stimulated by the laser radiation. Our findings encourage further research works on the influence of optical radiation onto stem cells and tissue regeneration. (c) 2005 Elsevier B.V. All rights reserved.

Effect of the clinical application of the GaAlAs laser in the treatment of dentine hypersensitivity

Objective: the aim of this study was to evaluate the effectiveness of the clinical use of the gallium-aluminum-arsenium (GaAlAs) laser at the maximum and minimum energies recommended by the manufacturer for the treatment of dentine hypersensitivity.Background Data: Dentine hypersensitivity (DH) is a response to a stimulus that would not usually cause pain in a healthy tooth. It is characterized by sharp pain of short duration from the denuded dentin. Its etiology is unknown. The dentin only begins to show sensitivity when exposed to the buccal environment. This exposure can result after removal of the enamel and/or dental cement, or after root denudation. Different treatments are proposed for this disorder.Materials and Methods: In this study, 25 patients, with a total number of 106 cases of DH, were treated with GaAlAs low-level laser therapy (LLLT). 65% of the teeth were premolars; 14% were incisors and molars; 6.6% were canines. The teeth were irradiated with 3 and 5 J/cm(2) for up to six sessions, with an interval of 72 It between each application, and they were evaluated initially, after each application, and at 15 and 60 days follow-up post-treatment.Results: the treatment was effective in 86.53% and 88.88% of the irradiated teeth, respectively, with the minimum and maximum energy recommended by the manufacturer. There was a statistically significant difference between DH and after a follow-up of 60 days for both groups. The difference among the energy maximum and minimum was not significant.Conclusion: the GaAlAs low-level laser was effective in reducing initial DH. A significant difference was found between initial values of hypersensitivity and after 60 days follow-up post-treatment. No significant difference was found between minimum (3 J/cm(2)) and maximum (5 J/cm(2)) applied energy.

Dynamics of Tm-Ho energy transfer and deactivation of the F-3(4) low level of thulium in fluorozirconate glasses

The mechanism involved in the Tm3+ (F-3(4))-->Ho3+ (I-5(7)) energy transfer and Tm3+ (H-3(4), H-3(6))-->Tm3+ (F-3(4), F-3(4)) cross relaxation as a function of the donor and acceptor concentrations was investigated in Tm-Ho-codoped fluorozirconate glasses. The experimental transfer rates were determined for the Tm-->Ho energy transfer from the best fit of the acceptor luminescence decay using an expression which takes into account the Inokuti-Hirayama model and localized donor-to-acceptor interaction solution. The original acceptor solution derived from the Inokuti-Hirayama model fits well the acceptor luminescence transient only for low-concentrated systems. The results showed that a fast excitation diffusion that occurs in a very short time (t<Tm cross relaxation and Tm-->Ho energy transfer ions from H-3(4) and F-3(4) thulium states, respectively. (C) 2004 American Institute of Physics.

Photosensitization of different Candida species by low power laser light

The aim of this study was to evaluate the effects of the laser radiation (685 nm) associated with photosensitizers on viability of different species of Candida genus. Suspensions of Candida albicans, Candida dubliniensis, Candida krusei and Candida tropicalis, containing 106 viable cells per milliliter were obtained with the aid of a Neubauer's chamber. From each species, 10 samples of the cell suspension were irradiated with diode laser (685 nm) with 28 J/cm(2) in the presence of methylene blue (0.1 mg/ml), 10 samples were only treated with methylene blue, 10 samples were irradiated with laser in the absence of the dye, 10 samples were treated with the dye and irradiated with laser light and 10 samples were exposed to neither the laser light nor to the methylene blue dye. From each sample, serial dilutions of 10(-2) and 10(-3) were obtained and aliquots of 0.1 ml of each dilution were plated in duplicate on Sabouraud dextrose agar. After incubation at 37 degrees C for 48 h, the number of colony-forming units (CFU/ml) was obtained and data were submitted to ANOVA and Tukey's test (p < 0.05). Laser radiation in the presence of methylene blue reduced the number of CFU/ml in 88.6% for C. albicans, 84.8% for C. dubliniensis, 91.6% for C krusei and 82.3% for C tropicalis. Despite of this, only laser radiation or methylene blue did not reduce significantly the number of CFU/ml of Candida samples, except for C tropicalis. It could be concluded that the photo activation of methylene blue by the red laser radiation at 685 nm presented fungicide effect on all Candida species studied. (c) 2006 Elsevier B.V. All rights reserved.

Low intensity laser therapy (LILT) in vivo acts on the neutrophils recruitment and chemokines/cytokines levels in a model of acute pulmonary inflammation induced by aerosol of lipopolysaccharide from Escherichia coli in rat

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Laser 904 nm action on bone repair in rats with osteoporosis

The aim of the present study was to determine the action of AsGA laser irradiation on bone repair in the tibia of osteopenic rats. The animals were randomly divided into eight experimental groups according to the presence of ovarian hormone (sham group) or the absence of the hormone (OVX group), as well as being irradiated or non-irradiated. Low-level 904-nm laser (50 mJ/cm(2)) accelerated the repair process of osteopenic fractures, especially in the initial phase of bone regeneration.Introduction The development of new techniques to speed the process of bone repair has provided significant advances in the treatment of fractures. Some attention recently focused on the effects of biostimulation on bone.Methods Forty-eight adult rats were randomly divided into eight experimental groups (six animals in each group) according to the presence of ovarian hormone (sham group) or absence of the hormone (ovariectomized (OVX) group) as well as being irradiated or non-irradiated. For the application of low-level laser therapy, the animals were anesthetized with one third of the dose sufficient to immobilize the animal and irradiated with AsGa laser (904 nm, 50 mJ/cm(2) for 2s, point form and in contact). The control animals received the same type of manipulation as the irradiated animals, but with the laser turned off. Half of the animals were killed 7 days following the confection of the bone defect, and the other half were killed 21 days after the surgery. After complete demineralization, the tibias were cut cross-sectionally in the central region of the bone defect and embedded in paraffin blocks. The blocks were then cut in semi-seriated slices and stained with hematoxylin and eosin.Results There was new bone formation in the animals in the OVX group with laser treatment killed after 7 days (p<0.001). The lowest percentage of bone formation was observed in the OVX without laser killed after 7 days (p>0.05). All animals killed after 21 days exhibited linear closure of the lesion.Conclusion Low-level 904-nm laser (50 mJ/cm(2)) accelerated the repair process of osteopenic fractures, especially in the initial phase of bone regeneration.