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PubMed1987

Current laser dentistry.

Current laser dentistry since our initial studies in 1964 is reviewed. Three areas are considered: routine dental office practice, tooth restoration, and oral surgery. For tooth restoration and oral surgery, CO2 and neodymium:YAG lasers are used and lasers are used in photodynamic therapy for oral cancer. Dental office practice today is concerned mostly with uncontrolled studies of biostimulation and requires more basic research and controlled clinical studies. The laser industry in the United States should take a more active interest in defining the applications of lasers in dentistry.

Dentistry, Operative↗
PubMed1987

Bone fracture consolidates faster with low-power laser.

Low-power laser radiation is currently used in the treatment of pain and osteoarticular inflammation. However, the mechanisms of the laser biostimulating effects on tissue are still not completely understood. With laser treatment, we have achieved activation of osseous regeneration in human bone fractures. After 7 years of positive clinical control in human beings, we decided to start an experimental study of fractures in the tibia of mice, histologically controlling its reparation after exposure to 632 nm. He/Ne laser in doses of 2.4 Joules in one point was used. The radiation was directly applied to the area of fracture in a series of 12 treatments (one treatment every second day). By optic microscope we observed, in the treated animals, an important increase in vascularization and faster formation of osseous tissue with a dense trabecular net compared to the control group, which presented only chondroid tissue and poor vascularization corresponding to an earlier stage of bone consolidation (controls were also analyzed by electron microscopy). Potentially, the laser effect might modulate the function of osteocytes, promoting faster metabolism and reaction of bone callus.

Animals↗
PubMed1987

Simple and sensitive CO2 laser visual screen.

The present paper describes a simple and sensitive CO2 laser visual screen which is made from silica gel with cobalt chloride as indicator. The screen can directly and almost immediately display a clear mode pattern of an exposing CO2 laser beam, it can respond to laser intensities ranging from 80 mW/cm2 to 26 W/cm2. It is suitable for the observation of both high-power lasers, which are used for surgery, and very low power ones, which are used for biostimulation.

Carbon Dioxide↗
PubMed1989

Effect of helium-neon and infrared laser irradiation on wound healing in rabbits.

We examined the biostimulating effects of helium-neon laser radiation (HeNe; 632.8 nm), pulsed infrared laser radiation (IR; 904 nm), and the two combined on skin wound healing in New Zealand white rabbits. Seventy-two rabbits received either 1) no exposure, 2) 1.65 J/cm2 HeNe, 3) 8.25 J/cm2 pulsed IR, or 4) both HeNe and IR together to one of two dorsal full-thickness skin wounds, daily, for 21 days. Wound areas were measured photographically at periodic intervals. Tissue samples were analyzed for tensile strength, and histology was done to measure epidermal thickness and cross-sectional collagen area. Significant differences were found in the tensile strength of all laser-treated groups (both the irradiated and nonirradiated lesion) compared to group 1. No differences were found in the rate of wound healing or collagen area. Epidermal growth was greater in the HeNe-lased area compared to unexposed tissue, but the difference was not significant. Thus, laser irradiation at 632.8 nm and 904 nm alone or in combination increased tensile strength during wound healing and may have released tissue factors into the systemic circulation that increased tensile strength on the opposite side as well.

Animals↗
PubMed1989

Effect of low-energy laser irradiation on colony formation capability in different human tumor cells in vitro.

Fibroblasts and lymphocytes are the most widely used cells for studying the so-called biostimulative effect of low-power laser in vitro. In contrast, stimulation of cancer cells by laser light has not been investigated extensively. The present study attempted to evaluate whether or not human tumor cells could exhibit an increase in colony-forming capability following low-watt laser irradiation. LoVo and HT29 (colon carcinoma), MCF7 (breast carcinoma), M14 and JR1 (malignant melanoma) cell lines were irradiated at different doses of light delivered from an argon or an argon-dye laser. Radiant exposures between 4.2 and 150 kJ/m2 at irradiances ranging from 35 to 500 W/m2 were delivered. Results were mixed. Of the 41 experiments performed, five showed a significant statistical increase in the number of colonies (P less than 0.05), whereas three showed a decrease (P less than 0.05). Nevertheless, the trend of most data was toward an increase in colony formation, and Wilcoxon's signed-ranks test suggested that light increases tumor cell culture growth (P less than 0.03).

Breast Neoplasms↗
PubMed1990

Laser photobioactivation mechanisms: in vitro studies using ascorbic acid uptake and hydroxyproline formation as biochemical markers of irradiation response.

Clinical investigations of laser photobioactivation, or biostimulation, might be differently designed and more fruitful if knowledge of basic biochemical mechanisms were better understood. In this investigation, biochemical events identified as responses to 904 nm irradiation included increased ascorbic acid uptake by fibroblasts. These cells also showed increased hydroxyproline formation, and this was increased several-fold by the addition of proline to the medium. Maximum biochemical responses were observed at a pulse frequency of 67 Hz and a pulse width of 150 nsec with an energy density of approximately 7 mJ/cm2 per exposure. Elements in the mitochondrial cytochrome system are proposed as the radiation absorbing chromophore(s). Hypothetically, the energy generated is linked to ascorbic acid uptake, which in turn stimulates collagen synthesis.

Ascorbic Acid↗
PubMed2004

Effect of low-power He-Ne laser irradiation on rabbit articular chondrocytes in vitro.

BACKGROUND AND OBJECTIVES: In the orthopaedic field, the repair of articular cartilage is still a difficult problem, because of the physiological characters of cartilaginous tissues and chondrocytes. To find an effective method of stimulating their regeneration, this in vitro study focuses on the biostimulation of rabbit articular chondrocytes by low-power He-Ne laser. STUDY DESIGN/MATERIALS AND METHODS: The articular chondrocytes isolated from the cartilage of the medial condyle of the femur of the rabbit were incubated in DMEM/HamF(12) medium. The second passage culture were spread on 24 petri dishes and were irradiated with laser at power output of 2-12 mW for 6.5 minutes, corresponding to the energy density of 1-6 J/cm(2). Laser treatment was performed three times at a 24-hour interval. After lasering, incubation was continued for 24 hours. Non-irradiated cells were kept under the same conditions as the irradiated ones. The cell proliferation activity was evaluated with a XTT colorimetric method and the cell secretion activity was analyzed by metachromasia and immunocytochemistry. RESULTS: Irradiation of 4-6 J/cm(2) increased the cell numbers and revealed a considerably higher cell proliferation activity comparing to control cultures. Thereinto, the energy density of 4 and 5 J/cm(2) remarkably increased cell growth, with positive effect on synthesis and secretion of extracellular matrix. CONCLUSIONS: The present study showed that a particular laser irradiation stimulates articular chondrocytes proliferation and secretion. These findings might be clinically relevant, indicating that low-power laser irradiation treatment is likely to achieve the repair of articular cartilage in clinic.

Animals↗
PubMed2004

Low level laser irradiation stimulates mitochondrial membrane potential and disperses subnuclear promyelocytic leukemia protein.

BACKGROUND AND OBJECTIVES: Low level laser irradiation (LLLI) is used to promote wound healing. Molecularly it is known to stimulate mitochondrial membrane potential (MMP), cytokine secretion, and cell proliferation. This study was designed to determine the influence of LLLI on the kinetics of MMP stimulation and decay, specific cytokine gene expression, and subcellular localization of promyelocytic leukemia (PML) protein on HaCaT human keratinocytes. STUDY DESIGN/MATERIAL AND METHODS: The cells were irradiated by a 780 nm titanium-sapphire (Ti-Sa) laser with 2 J/cm(2) energy density. MMP was monitored with Mitotracker, a mitochondrial voltage-sensitive fluorescent dye. Cytokine gene expression was carried out using semi-quantitative-reverse transcription polymerase chain reaction. Subcellular localization of PML protein, a cell-cycle checkpoint protein, was determined using immunofluorescent staining. RESULTS: The fluorescence intensity of MMP was increased immediately after the end of LLLI by 148 +/- 6% over control (P<0.001). Subsequently it decayed, reaching 51 +/- 14% of the control level (P < 0.01) within 200 minutes. This decay was characterized by an exponential curve (R = 0.96) with a lifetime of 79 +/- 36 minutes (P < 0.05). Following irradiation, the expression of interleukin-1alpha, interleukin-6, and keratinocyte growth factor (KGF) genes were transiently upregulated; but the expression of the proinflammatory gene interleukin-1beta, was suppressed. The subnuclear distribution of PML was altered from discrete domains to its dispersed form within less than 1 hour after LLLI. CONCLUSIONS: These changes reflect a biostimulative boost that causes a shift of the cell from a quiescent to an activated stage in the cell cycle heralding proliferation and suppression of inflammation. Further characterization of MMP kinetics may provide a quantitative basis for assessment of the effect of LLLI in the clinical setting.

Cells, Cultured↗
PubMed2005

Flavins are source of visible-light-induced free radical formation in cells.

BACKGROUND AND OBJECTIVES: It has been hypothesized that reactive oxygen species (ROS) are created by an endogenous photosensitizer during low energy visible light illumination of tissue, and these ROS are responsible for reported biostimulative effects. This study aims to identify the endogenous photosensitizer responsible for ROS production by visible light. STUDY DESIGN/MATERIALS AND METHODS: Electron paramagnetic resonance (EPR) spectroscopy was used to detect oxyradicals produced in cardiac and sperm cells during illumination by a halogen lamp. Oxyradical production was determined as a function of illumination wavelength, cell fraction, and molecular weight. RESULTS: Oxyradicals were created solely by the 400-500 nm range of visible light. The endogenous photosensitizer is found predominantly in the cytosol and is smaller than 12 kD. Flavin mononucleotide produces the same signal at concentrations consistent with reported intracellular free flavin concentrations. CONCLUSIONS: A small, water soluble photosensitizer active only at wavelengths shorter than 500 nm is consistent with a flavin, which reproduces cellular signals at physiological concentrations. Thus, flavins are responsible for the photosensitization of the observed oxyradicals in cells.

Animals↗
PubMed1990

The use of infrared laser therapy in the treatment of venous ulceration.

Management of intractable venous ulceration remains an unrewarding task which is increasingly delegated to the realm of the vascular surgeon. The purpose of this pilot study was to assess the ulcer-healing effects of the newest form of biostimulation--the low power laser. Twelve patients with chronic venous ulcers unresponsive to conservative measures were treated with infrared laser irradiation for twelve weeks. Two ulcers healed completely and there was a 27% (p less than 0.01) reduction in size of the remaining ulcers. Treatment resulted in a 44% (p less than 0.01) increase in ulcer floor area occupied by healthy granulation tissue. The most dramatic effect of laser treatment was the reduction in ulcer pain, from 7.5 to 3.5 (linear analogue scale) (p less than 0.001). Laser irradiation had no effect on TcPO2, number of skin capillaries or pericapillary fibrin deposition in the lipodermatosclerotic area around the ulcer. The results of this pilot study are encouraging and a carefully controlled randomized study is indicated to compare low power laser irradiation to conventional treatment in the management of venous ulcers.

Blood Gas Monitoring, Transcutaneous↗
PubMed1993

Bioremediating herbicide-contaminated soils.

Combinations of landfarming and biostimulation were evaluated for remediating pesticide wastes. Various amounts of soil contaminated with alachlor and trifluralin (> or = 100 mg/kg each) and metolachlor and atrazine (> or = 20 mg/kg each) were applied to field plots, and sewage sludge or corn meal was incorporated into designated plots. Plots were also treated with fresh spray mixtures in amounts similar to those applied as contaminated soil. Soil bioactivity and dissipation of parent herbicides were monitored after the treatments. During 100 d, soil dehydrogenase activities were highest in organic-material-amended plots. During the same period, the levels of alachlor had declined by 85-95% in amended, contaminated soil-treated plots and by 75-85% in corresponding unamended plots. In freshly sprayed plots, 95-100% of the initial doses of alachlor had dissipated in amended plots, and 85-95% was lost in corresponding unamended plots. The levels of trifluralin had declined by 70-80% in corn-meal-amended plots and by 60-75% in unamended plots. There were no significant differences between dissipation of trifluralin applied as contaminated soil or fresh sprays.

Biodegradation, Environmental↗
PubMed2001

The effect of He-Ne laser (632.8 nm) and Solcoseryl in vitro.

He-Ne laser (632.8 nm) and Solcoseryl (SS), a non-protein calf haemodialysate, were used in the enhancement of wound healing. Nonetheless, a study on the use of He-Ne laser with SS has not been done. The purpose of this study is to determine the effect of He-Ne laser biostimulation in combination with SS on Chinese hamster ovary (CHO) and human skin fibroblast (HSF). A dose response for the cloning efficiency (CE) of CHO and HSF cells in 5% fetal bovine serum in minimum essential medium (FBS-MEM) with 6-125 micrograms/ml SS and He-Ne laser using an optimum power density of 1.25 mW/cm2 and cumulative doses (CD) of 60-600 mJ/cm2 given for three consecutive days, were done. The combined effects of He-Ne laser 180 mJ/cm2 with 6 and 12 micrograms/ml SS were determined. Quadruplicate cultures were done. Student t-test was used to determine differences of treatment groups from controls. CHO and HSF CE were increased using 180 mJ/cm2 laser by 13.1% +/- 4.5% (p < 0.0025) and 39.1% +/- 7.9% (p < 0.0005); SS 6 micrograms/ml by 14.4% +/- 8.7% (p = 0.01) and 20.7% +/- 10.9% (p = 0.01); SS 12 micrograms/ml by 17.7% +/- 6.3% (p = 0.001) and 23.9% +/- 5.6% (p < 0.0025); laser + SS 6 micrograms/ml by 15.1% +/- 8.8% (p < 0.01) and 60.9% +/- 9.4% (p < 0.0001); laser + SS 12 micrograms/ml by 23.0% +/- 1.5% (p < 0.0001) and 70.7% +/- 11.4% (p < 0.0001), respectively. Additional significant increases in CE were observed on CHO using laser + SS 12 micrograms/ml by 8.6% +/- 1.3% (p < 0.025) and on HSF using laser + SS 6 micrograms/ml and laser + SS 12 micrograms/ml by 15.6% +/- 6.8% (p < 0.025) and 22.7% +/- 10.6% (p = 0.01), respectively, when compared to the effect of 180 mJ/cm2 laser. Results suggest that further stimulation can be achieved by using He-Ne laser with SS. This could be exploited as a new treatment modality.

Actihaemyl↗
PubMed2005

[Venous leg ulcers: no improvement of wound healing with 685-nm low level laser therapy. Randomised, placebo-controlled, double-blind study].

INTRODUCTION: Venous leg ulcers (ulcera crurum venosa) are frequently seen in elderly patients. It has been suggested that low level laser irradiation has a biostimulative and wound healing effect; however, this has not yet been clinically verified by controlled studies. STUDY DESIGN: The difference in size reduction of leg ulcers with and without low level laser or placebo laser treatment was measured in 44 patients randomised into two treatment groups (685-nm low level laser and placebo laser) or a control group which served to quantify the effect of laser application. All patients received standardized wound care. OBJECTIVE: The aim of the study was to compare the effectiveness of low level laser irradiation with that of a placebo "light source". The size of the ulcers was planimetrically measured at baseline (day 1), at the end of therapy (day 28) and 2 months later (day 90). The difference in wound size was evaluated. RESULTS: There were no statistically significant differences in reduction of wound size between the three groups, thus suggesting that low level laser light does not have any stimulatory effect on wound healing in ulcera crurum venosa.

Adult↗
PubMed2004

Utilization of microbial biofilms as monitors of bioremediation.

A down-well aquifer microbial sampling system was developed using glass wool or Bio-Sep beads as a solid-phase support matrix. Here we describe the use of these devices to monitor the groundwater microbial community dynamics during field bioremediation experiments at the U.S. Department of Energy Natural and Accelerated Bioremediation Research Program's Field Research Center at the Oak Ridge National Laboratory. During the 6-week deployment, microbial biofilms colonized glass wool and bead internal surfaces. Changes in viable biomass, community composition, metabolic status, and respiratory state were reflected in sampler composition, type of donor, and groundwater pH. Biofilms that formed on Bio-Sep beads had 2-13 times greater viable biomass; however, the bead communities were less metabolically active [higher cyclopropane/monoenoic phospholipid fatty acid (PLFA) ratios] and had a lower aerobic respiratory state (lower total respiratory quinone/ PLFA ratio and ubiquinone/menaquinone ratio) than the biofilms formed on glass wool. Anaerobic growth in these systems was characterized by plasmalogen phospholipids and was greater in the wells that received electron donor additions. Partial 16S rDNA sequences indicated that Geobacter and nitrate-reducing organisms were induced by the acetate, ethanol, or glucose additions. DNA and lipid biomarkers were extracted and recovered without the complications that commonly plague sediment samples due to the presence of clay or dissolved organic matter. Although microbial community composition in the groundwater or adjacent sediments may differ from those formed on down-well biofilm samplers, the metabolic activity responses of the biofilms to modifications in groundwater geochemistry record the responses of the microbial community to biostimulation while providing integrative sampling and ease of recovery for biomarker analysis.

Acetates↗
PubMed1998

Low-temperature bioremediation of a waste water contaminated with anionic surfactants and fuel oil.

We conducted a laboratory study at 10 degrees C on the biological decontamination of the waste water from a garage and car-wash that was contaminated with anionic surfactants (57 mg 1(-1)) and fuel oil (184 mg hydrocarbons 1(-1)). The indigenous microorganisms degraded both contaminants efficiently after biostimulation by an inorganic nutrient supply. After 7 days at 10 degrees C, the residual contaminations were 11 mg anionic surfactants 1(-1) and 26 mg hydrocarbons 1(-1). After 35 days, only the anionic surfactants had been further reduced to 3 mg 1(-1). Bioaugmentation of the unfertilized waste water with a cold-adapted inoculum, able to degrade both hydrocarbons (diesel oil) and anionic surfactants (sodium dodecyl sulphate), resulted in a significant increase of the hydrocarbon biodegradation during the first 3 days of decontamination, whereas biodegradation of anionic surfactants was inhibited during the first 21 days following inoculation. Bioaugmentation of the nutrient-amended waste water was without any effect.

Biodegradation, Environmental↗
PubMed2006

Different photoresponses of Staphylococcus aureus and Pseudomonas aeruginosa to 514, 532, and 633 nm low level lasers in vitro.

Low Level Light irradiation (LLLI) may proliferate cell growth at certain conditions during a set of photochemical reactions called biostimulation. However, phototoxic inhibitory reactions after irradiating natural or artificially inoculated cells are possible. The purpose of this study was to determine these effects on Pseudomonas aeruginosa and Staphylococcus aureus. Ar ion laser at 514 nm was used to determine the effect of various energy densities of green light on these bacteria. The most effective energy densities of Ar ion laser were chosen to irradiate both bacteria with He-Ne (633 nm) and SHG Nd:YAG (532 nm) lasers to compare the effect of red and green lights on the growth. Irradiation of Pseudomonas aeruginosa for both He-Ne and SHG Nd:YAG lasers in the presence of toluidine blue O or safranine O as photosensitizers was also studied. All energy densities of Ar ion laser showed a proliferative effect on Pseudomonas aeruginosa and inhibitory effect on Staphylococcus aureus. Similarly, SHG Nd:YAG and He-Ne lasers with chosen energy densities were again proliferating for Pseudomonas aeruginosa and inhibitory for Staphylococcus aureus and SHG Nd:YAG was more effective than He-Ne in both cases. Irradiation of Pseudomonas aeruginosa in the presence of both photosensitizers led to the decrease of the cell population compared to the control.

Argon↗
PubMed1999

Ultrastructural study of the destructive and repair processes in pulmonary inflammation and following endobronchial laser therapy.

Examination of 127 biopsy specimens from 45 patients with inflammatory lung diseases showed changes consistent with increased permeability of the capillary endothelial cells as an initial stage in the development of the inflammatory reaction. Associated interstitial oedema, deformation of the interalveolar septa, and structural disorganization of alveolar epithelium cells occur, and local microcirculatory problems result in tissue hypoxia and fibrosis. The ultimate morphological picture is determined largely by the intensity of repair. Laser biostimulation minimizes the inflammation and stabilizes fibroplastic process.

Bronchi↗
PubMed2005

Evaluation of different bioremediation protocols to enhance decomposition of organic polymers in harbour sediments.

The response of the microbial community (in term of abundance and enzymatic activity) was investigated to test the effect of different bioremediation protocols to naturally enhance decomposition of organic polymers in harbour sediments (Genoa Harbour, Italy, N-W Mediterranean). Bioremediation techniques tested were bioaugmentation (5 different microorganisms' inocula), biostimulation (air supply), and natural attenuation. The coupling bioaugmentation/biostimulation was also tested. After 60 days, following the bioaugmentation protocol, bacterial densities correlated to the quantities of inocula amended to the boxes, suggesting that allochthonous community was able to survive and multiply. However, while bioaugmentation alone seems not to be able to carry out significative degradation, its coupling with air insufflations produced the best response: here bacterial densities increased, especially in the water (from 2.3 x 10(7) to 3.50 x 10(8) cells ml(-1)), average cell size and enzymatic activities increased, and sedimentary organic matter was significantly depleted (PRT 5-folds reduction, CHO 1.5-folds reduction). The strong coupling observed between the sediment and water compartments together with the greatest microbial response observed in this latter suggest that the sediment-water interface may constitute a key compartment for the occurring of biodegradation processes in organic-rich sediments.

Bacteria↗