Low-Level Laser Irradiation (InGaAlP-660 nm) Increases Fibroblast Cell Proliferation and Reduces Cell Death in a Dose-Dependent Manner

Background and Objective: Impaired cell metabolism and increased cell death in fibroblast cells are physiological features of chronic tendinopathy. Although several studies have shown that low-level laser therapy (LLLT) at certain parameters has a biostimulatory effect on fibroblast cells, it remains uncertain if LLLT effects depend on the physiological state. Study Design/Material and Methods: High-metabolic immortal cell culture and primary human keloid fibroblast cell culture were used in this study. Trypan blue exclusion and the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) test were used to determine cell viability and proliferation. Propidium iodide stain was used for cell-cycle analysis by flow cytometry. Laser irradiation was performed daily on three consecutive days with a GaAlAs 660-nm laser (mean output: 50 mW, spot size 2 mm(2), power density = 2.5 W/cm(2)) and a typical LLLT dose and a high LLLT dose (irradiation times: 60 or 420 s; fluences: 150 or 1050 J/cm(2); energy delivered: 3 or 21 J). Results: Primary fibroblast cell culture from human keloids irradiated with 3 J showed significant proliferation by the trypan blue exclusion test (p < 0.05), whereas the 3T3 cell culture showed no difference using this method. Propidium iodide staining flow cytometry data showed a significant decrease in the percentage of cells being in proliferative phases of the cell cycle (S/g(2)/M) when irradiated with 21 J in both cell types (hypodiploid cells increased). Conclusions: Our data support the hypothesis that the physiological state of the cells affects the LLLT results, and that high-metabolic rate and short-cell-cycle 3T3 cells are not responsive to LLLT. In conclusion, LLLT with a dose of 3 J reduced cell death significantly, but did not stimulate cell cycle. A LLLT dose of 21 J had negative effects on the cells, as it increased cell death and inhibited cell proliferation.

The effect of low-level laser irradiation (In-Ga-Al-AsP-660 nm) on melanoma in vitro and in vivo

Background: It has been speculated that the biostimulatory effect of Low Level Laser Therapy could cause undesirable enhancement of tumor growth in neoplastic diseases. The aim of the present study is to analyze the behavior of melanoma cells (B16F10) in vitro and the in vivo development of melanoma in mice after laser irradiation. Methods: We performed a controlled in vitro study on B16F10 melanoma cells to investigate cell viability and cell cycle changes by the Tripan Blue, MTT and cell quest histogram tests at 24, 48 and 72 h post irradiation. The in vivo mouse model (male Balb C, n = 21) of melanoma was used to analyze tumor volume and histological characteristics. Laser irradiation was performed three times (once a day for three consecutive days) with a 660 nm 50 mW CW laser, beam spot size 2 mm(2), irradiance 2.5 W/cm(2) and irradiation times of 60s (dose 150 J/cm(2)) and 420s (dose 1050 J/cm(2)) respectively. Results: There were no statistically significant differences between the in vitro groups, except for an increase in the hypodiploid melanoma cells (8.48 +/- 1.40% and 4.26 +/- 0.60%) at 72 h postirradiation. This cancer-protective effect was not reproduced in the in vivo experiment where outcome measures for the 150 J/cm(2) dose group were not significantly different from controls. For the 1050 J/cm(2) dose group, there were significant increases in tumor volume, blood vessels and cell abnormalities compared to the other groups. Conclusion: LLLT Irradiation should be avoided over melanomas as the combination of high irradiance (2.5 W/cm(2)) and high dose (1050 J/cm(2)) significantly increases melanoma tumor growth in vivo.

In vitro analysis of human tooth pulp chamber temperature after low-intensity laser therapy at different power outputs

In vitro studies have provided conflicting evidence of temperature changes in the tooth pulp chamber after low-level laser irradiation of the tooth surface. The present study was an in vitro evaluation of temperature increases in the human tooth pulp chamber after diode laser irradiation (GaAlAs, lambda = 808 nm) using different power densities. Twelve human teeth (three incisors, three canines, three premolars and three molars) were sectioned in the cervical third of the root and enlarged for the introduction of a thermocouple into the pulp chamber. The teeth were irradiated with 417 mW, 207 mW and 78 mW power outputs for 30 s on the vestibular surface approximately 2 mm from the cervical line of the crown. The highest average increase in temperature (5.6A degrees C) was observed in incisors irradiated with 417 mW. None of the teeth (incisors, canines, premolars or molars) irradiated with 207 mW showed temperature increases higher than 5.5A degrees C that could potentially be harmful to pulp tissue. Teeth irradiated with 78 mW showed lower temperature increases. The study showed that diode laser irradiation with a wavelength of 808 nm at 417 mW power output increased the pulp chamber temperature of certain groups of teeth, especially incisors and premolars, to critical threshold values for the dental pulp (5.5A degrees C). Thus, this study serves as a warning to clinicians that ""more"" is not necessarily ""better"".

In vitro effect of low-level laser on odontoblast-like cells

The aim of this study was to evaluate the metabolism of odontoblast-like MDPC-23 cells subjected to direct LLL irradiation. The cells were seeded (20,000 cells/well) in 24-well plates and incubated for 24 hours at 37 degrees C. After this period, the culture medium (DMEM) was replaced by fresh DMEM supplemented with 2 or 5% (stress induction by nutritional deficit) or 10% fetal bovine serum (FBS). The cells were exposed to laser doses of 2, 4, 10, 15 and 25 J/cm(2) from a near infrared InGaAsP diode laser prototype (LASERTable; 780 +/- 3 nm, 40 mW). One control group (sham irradiation) was established for each experimental condition (laser dose x FBS supplementation). Three and 72 hours after the last irradiation, cells were analyzed with respect to metabolism, morphology, total protein expression and alkaline phosphatase (ALP) activity. Higher metabolism and total protein expression were observed 72 hours after the last irradiation at the doses of 15 and 25 J/cm(2) (Mann-Whitney; p<0.05). Higher ALP activity was obtained with 5% FBS when the cells were irradiated with doses of 2 and 10 J/cm(2). For the dose of 25 J/cm(2), the highest ALP activity was observed with 10% FBS. It was concluded that the LLLT parameters used in this study stimulated the metabolic activity of the MDPC-23 cells, especially at the doses of 15 and 25 J/cm(2).

Increased Viability of Odontoblast-Like Cells Subjected to Low-Level Laser Irradiation

Studies have shown that the increase of cell metabolism depends on the low level laser therapy (LLLT) parameters used to irradiate the cells. However, the optimal laser dose to up-regulate pulp cell activity remains unknown. Consequently, the aim of this study was to evaluate the metabolic response of odontoblast-like cells (MDPC-23) exposed to different LLLT doses. Cells at 20000 cells/cm(2) were seeded in 24-well plates using plain culture medium (DMEM) and were incubated in a humidified incubator with 5% CO(2) at 37 degrees C. After 24 h, the culture medium was replaced by fresh DMEM supplemented with 5% (stress by nutritional deficit) or 10% fetal bovine serum (FBS). The cells were exposed to different laser doses from a near infrared diode laser prototype designed to provide a uniform irradiation of the wells. The experimental groups were: G1: 1.5 J/cm(2) + 5% FBS; G2: 1.5 J/cm(2) + 10% FBS; G3: 5 J/cm(2) + 5% FBS; G4: 5 J/cm(2) + 10% FBS; G5: 19 J/cm(2) + 5% FBS; G6: 19 J/cm(2) + 10% FBS. LLLT was performed in 3 consecutive irradiation cycles with a 24-hour interval. Non-irradiated cells cultured in DMEM supplemented with either 5 or 10% FBS served as control groups. The analysis of the metabolic response was performed by the MTT assay 3 h after the last irradiation. G1 presented an increase in SDH enzyme activity and differed significantly (Mann-Whitney test, p < 0.05) from the other groups. Analysis by scanning electron microscopy showed normal cell morphology in all groups. Under the tested conditions, LLLT stimulated the metabolic activity of MDPC-23 cultured in DMEM supplemented with 5% FBS and exposed to a laser dose of 1.5 J/cm(2). These findings are relevant for further studies on the action of near infrared lasers on cells with odontoblast phenotype.

Effect of low-level laser irradiation on odontoblast-like cells

Low-level laser therapy (LLLT), also referred to as therapeutic laser, has been recommended for a wide array of clinical procedures, among which the treatment of dentinal hypersensitivity. However, the mechanism that guides this process remains unknown. Therefore, the objective of this study was to evaluate in vitro the effects of LLL irradiation on cell metabolism (MTT assay), alkaline phosphatase (ALP) expression and total protein synthesis. The expression of genes that encode for collagen type-1 (Col-1) and fibronectin (FN) was analyzed by RT-PCR. For such purposes, oclontoblast-like cell line (MDPC-23) was previously cultured in Petri dishes (15000 cells/cm(2)) and submitted to stress conditions during 12 h. Thereafter, 6 applications with a monochromatic near infrared radiation (GaAlAs) set at predetermined parameters were performed at 12-h intervals. Non-irradiated cells served as a control group. Neither the MTT values nor the total protein levels of the irradiated group differed significantly from those of the control group (Mann-Whitney test; p > 0.05). On the other hand, the irradiated cells showed a decrease in ALP activity (Mann-Whitney test; p < 0.05). RT-PCR results demonstrated a trend to a specific reduction in gene expression after cell irradiation, though not significant statistically (Mann-Whitney test; p > 0.05). It may be concluded that, under the tested conditions, the LLLT parameters used in the present study did not influence cell metabolism, but reduced slightly the expression of some specific proteins.

Increased Viability of Odontoblast-Like Cells Subjected to Low-Level Laser Irradiation

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

Effect of low-level laser irradiation on odontoblast-like cells

Low-level laser therapy (LLLT), also referred to as therapeutic laser, has been recommended for a wide array of clinical procedures, among which the treatment of dentinal hypersensitivity. However, the mechanism that guides this process remains unknown. Therefore, the objective of this study was to evaluate in vitro the effects of LLL irradiation on cell metabolism (MTT assay), alkaline phosphatase (ALP) expression and total protein synthesis. The expression of genes that encode for collagen type-1 (Col-1) and fibronectin (FN) was analyzed by RT-PCR. For such purposes, oclontoblast-like cell line (MDPC-23) was previously cultured in Petri dishes (15000 cells/cm(2)) and submitted to stress conditions during 12 h. Thereafter, 6 applications with a monochromatic near infrared radiation (GaAlAs) set at predetermined parameters were performed at 12-h intervals. Non-irradiated cells served as a control group. Neither the MTT values nor the total protein levels of the irradiated group differed significantly from those of the control group (Mann-Whitney test; p > 0.05). on the other hand, the irradiated cells showed a decrease in ALP activity (Mann-Whitney test; p < 0.05). RT-PCR results demonstrated a trend to a specific reduction in gene expression after cell irradiation, though not significant statistically (Mann-Whitney test; p > 0.05). It may be concluded that, under the tested conditions, the LLLT parameters used in the present study did not influence cell metabolism, but reduced slightly the expression of some specific proteins.

A histologic assessment of the influence of low-intensity laser therapy on wound healing in steroid-treated animals

Objective: the aim of the present study was to evaluate the effect of low-intensity laser therapy on the wound healing process treated with steroid. Background Data: Various biological effects have been associated with low-level laser therapy (LLLT). Materials and Methods: Forty-eight rats were used, and after execution of a wound on the dorsal region of each animal, they were divided into 4 groups (n = 12), receiving the following treatments: G1 (control), wounds and animals received no treatment; G2, wounds were treated with LLLT; G3, animals received an intraperitoneal injection of steroid dosage (2 mg/kg of body weight); G4, animals received steroid and wounds were treated with LLLT. The laser emission device used was a GaAIAs (904 nm), in a contact mode, with 2.75 mW gated with 2.900 Hz during 120 sec (33 J/cm(2)). After the period of 3, 7, and 14 days, the animals were sacrificed and the parts sent to histological processing and dyed using hematoxylin and eosin (HE) and Masson trichromium (MT) techniques. Results: the results have shown that the wounds treated with steroid had a delay in healing, while LLLT accelerated the wound healing process. Also, wounds treated with laser in the animals treated with steroid presented a differentiated healing process with a larger collagen deposition and also a decrease in both the inflamatory infiltrated and the delay on the wound healing process. Conclusion: LLLT accelerated healing, caused by the steroid, acting as a biostimulative coadjutant agent, balancing the undesirable effects of cortisone (in the tissue healing process.

Effect of Cycling Exercise at Different Pedal Cadences on Subsequent Muscle Strength

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

The influence of resistance exercise with emphasis on specific contractions (concentric vs. eccentric) on muscle strength and post-exercise autonomic modulation: a randomized clinical trial

Contextualização:Ações concêntricas apresentam maior estresse cardiovascular quando comparadas às excêntricas. Entretanto, não se sabe a influência desses tipos de ações no comportamento da modulação autonômica cardíaca durante o processo de recuperação pós-esforço.Objetivo:Comparar o efeito de um treinamento resistido para o grupo extensor do joelho realizado com ênfase concêntrica vs excêntrica sobre a força muscular e a recuperação pós-exercício considerando índices de variabilidade de frequência cardíaca (VFC) em jovens saudáveis.Método:Cento e cinco homens, com idades entre 18 e 30 anos, foram randomizados em quatro grupos: controle concêntrico (CCONC), controle excêntrico (CEXC), treinamento concêntrico (TCONC) e treinamento excêntrico (TEXC). Os grupos CCONC e CEXC realizaram uma sessão de exercício reduzido (ER) para o grupo extensor do joelho [três séries de uma repetição a 100% de uma repetição máxima (1RM)], e os grupos TCONC e TEXC realizaram dez sessões de treinamento. A VFC foi analisada no momento basal e na recuperação após as sessões (T1, T2, T3 e T4).Resultados:Observou-se aumento da força muscular para o grupo TEXC. Em relação à modulação autonômica cardíaca, observou-se, em comparação ao momento basal, aumento dos índices SDNN e SD2 no momento T1 nos grupos CCONC e CEXC e aumento dos índices RMSSD, SD1 e AF (ms2) nos momentos T1, T2 e T4 no grupo TEXC.Conclusões:Conclui-se que o treinamento resistido realizado com ênfase em contrações excêntricas promoveu ganho de força e aumento da modulação vagal cardíaca durante o processo de recuperação em relação à condição basal.

Connective tissue graft associated or not with low laser therapy to treat gingival recession: randomized clinical trial

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

Effects of high and low volume of strength training on muscle strength, muscle volume and lipid profile in postmenopausal women

Changes in lipid profile are considered a risk factor for cardiovascular disease (CVD), especially in postmenopausal woman who have been associated with age-related loss of muscle mass. The beneficial role of aerobic exercise in the prevention of CVD has been well documented. However, the effect of strength training has not been established. The purpose of this study was to determine the changes of lipoprotein levels after 12 weeks of different volumes of strength training and its correlation with strength and muscle volume in postmenopausal women. The participants were randomized into three groups: low volume (LVST; n = 12, 1 set) and high volume of strength training (HVST; n = 11, 3 sets), or control group (n = 12). Training groups performed 12 weeks of supervised strength exercises, 15 maximum repetitions, five times a week, 20 minutes for LVST and 40 minutes for HVST for each training session. Measurements included body composition, strength and muscle volume, as well as blood analysis (glucose, total cholesterol, triglycerides, low-density lipoprotein, and high-density lipoprotein) pre- and post-training. The HVST and LVST improved the one-repetition maximum knee extension strength (p < 0.001), maximal dynamic strength (p < 0.001), and muscle volume (p = 0.048). Post-training triglyceride was lower in HVST when compared to LVST and the control group (p = 0.047). Even though they present the same neuromuscular and morphological adaptations in postmenopausal women, the HVST is more effective than LVST in improving the lipid profile of postmenopausal woman, and can be considered as an ideal program of intervention to reverse changes in lipid metabolism commonly found in this group. Copyright (C) 2014, The Society of Chinese Scholars on Exercise Physiology and Fitness. Published by Elsevier (Singapore) Pte Ltd. All rights reserved.

Short-term low-intensity blood flow restricted interval training improves both aerobic fitness and muscle strength

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Effect of a low-level laser on bone regeneration after rapid maxillary expansion

Introduction: In this study, we evaluated the effects of a low-level laser on bone regeneration in rapid maxillary expansion procedures. Methods: Twenty-seven children, aged 8 to 12 years, took part in the experiment, with a mean age of 10.2 years, divided into 2 groups: the laser group (n=14), in which rapid maxillary expansion was performed in conjunction with laser use, and the no-laser group (n=13), with rapid maxillary expansion only. The activation protocol of the expansion screw was 1 full turn on the first day and a half turn daily until achieving overcorrection. The laser type used was a laser diode (TWIN Laser; MMOptics, Sao Carlos, Brazil), according to the following protocol: 780 nm wavelength, 40 mW power, and 10 J/cm(2) density at 10 points located around the midpalatal suture. The application stages were 1 (days 1-5 of activation), 2 (at screw locking, on 3 consecutive days), 3, 4, and 5 (7, 14, and 21 days after stage 2). Occlusal radiographs of the maxilla were taken with the aid of an aluminum scale ruler as a densitometry reference at different times: T1 (initial), T2 (day of locking), T3 (3-5 days after T2), T4 (30 days after T3), and T5 (60 days after T4). The radiographs were digitized and submitted to imaging software (Image Tool; UTHSCSA, San Antonio, Tex) to measure the optic density of the previously selected areas. To perform the statistical test, analysis of covariance was used, with the time for the evaluated stage as the covariable. In all tests, a significance level of 5% (P<0.05) was adopted. Results: From the evaluation of bone density, the results showed that the laser improved the opening of the midpalatal suture and accelerated the bone regeneration process. Conclusions: The low-level laser, associated with rapid maxillary expansion, provided efficient opening of the midpalatal suture and influenced the bone regeneration process of the suture, accelerating healing. (Am J Orthod Dentofacial Orthop 2012;141:444-50)