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[Light-emitting diodes (LED)].
Abstract
LED home-use is now widely spread. In dermatology, numerous reports have stated their results for many indications: wound healing process, rejuvenation, acne and, of course, photodynamic therapy. Nevertheless, fluence, pulse duration and color of the LED are so variable as it is difficult to bring well codified results. But how should you not be interested in this field? It is already any more a near future but well and truly a therapeutic reality...
... Light emitting diode, LED is a complex semiconductor coverts electrical signal into corresponding light signal. The advantages of using LED are small in size, high radiance which emit lots of light in a small area, high in reliability and can be modulated (turned on and off) at high speed [7].Based on the application that needs to be used, there are several LEDs' performance characteristics that can be determined such as peak wavelength, spectral width, emission pattern, power and speed. The peak wavelength is the wavelength where the source emits most power. ...
... The peak wavelength is the wavelength where the source emits most power. Spectral width is the range of wavelength that light is emitted in practise which also known as spectral width of the source [7]. There are two types of LED structures which are edge emitters and surface emitters. ...
... While surface emitter LED have simple structure and comparatively inexpensive. It offers low to moderate output power levels and low to moderate operating speed [7].LED optical output is approximately proportional to drive current. Temperature is one of the factors that affect the optical output. ...
Previously, many researches had been done on non-invasive using near-infrared sensing. Sia had investigated near-infrared sensing using signal penetrating finger method. However, by using finger penetration, there are no results obtained. He only obtained signal using glucose concentration. Therefore the objectives of this research are to investigate the performance of three different wavelength of sensors; infrared 940nm and 950nm and also near-infrared 1450nm. Sensor that gave the best output had been chosen to design a non-invasive optical blood glucose measurement device. Generally, the overall system consists of three parts including sensor part, signal conditioning circuit, and also numerical display. The initial design tested by considering initial voltage 1.616V to 1.68V which referred to previous research by Sia as the output of the sensor. Then proceed by using test tube which contains various percentage of glucose concentration. The same methods had been used to the human samples fingers instead of test tube. From the experiment, output graph of the 950nm shows more consistent pattern compared to the 940nm. 950nm also has a larger range scale for voltage which from 5.016V to 5.4633V compare to the 940nm voltage range scale which from 5.0327V to 5.4201V. Further test on human finger had been done by using 950nm infrared but the output voltages were too small. The performance of the measurement can be improved by controlling the surrounding condition and fixed the path length between transmitter and receiver. Test using test tube showed that the near infrared and infrared were capable to predict different glucose concentration. By using circuit designed, it can be seen that the voltage reading became higher compared to before meal. Therefore, it can be concluded that the circuit design functions accordingly and also the non-invasive. During human sample test, increment pattern can be seen from fasting to non-fasting condition but the main effect is all samples have different fingers' diameter which each of user needs to be calibrated.
IntroductionLED light therapy with magnetostimulation (magnetoledtherapy) has a vast range of applications in the treatment of neurological, rheumatic and orthopedic illnesses. In some cases it serves as an alternative procedure to pharmacological treatment, in particular to nonsteroidal anti-inflammatory drugs.AimThe aim of this study was to discuss the use of magnetoledtherapy in the rehabilitation of children.Materials and methodsThis article is a review of selected literature and other available source materials.DiscussionDue to biological hysteresis, therapeutic outcomes of magnetoledtherapy appear later than in the case of other physical therapy methods; they last longer, even up to several months after the exposure, thus leading to more beneficial treatment effects. Therapeutic methods available for very young people are limited due to various contraindications. When exposure conditions are carefully considered and accounted for, magnetoledtherapy can be applied even in infants, serving as a beneficial complement to kinesiotherapy. Children willingly participate in such treatment because magnetoledtherapy produces few side effects and has a positive effect on a patient's well-being following the application. Selected indications for the use of this method in children include neuralgias, juvenile rheumatoid arthritis, collagenoses, aseptic necrosis, osteoporosis, tendinitis, tendovaginitis, bursitis, injuries without a disruption in tissue continuity including sprains, bruises and fractures, improvement in the quality and time of healing, burns, effects of exposure to sunlight and laser light, neonatal physiological jaundice, dermatoses including dermatitises, acne, herpes, vitiligo, psoriasis, central nervous system lesions, dental periapical lesions, cerebral palsy, peripheral nerve lesions, especially perinatal brachial plexus palsy, polyneuropathies, amyotrophic lateral sclerosis, spinal muscular atrophy, muscular dystrophies, congenital bone deformations, neuroses, sleep disorders, stress, Attention Deficit Hyperactivity Disorder (ADHD), speech impairment therapy and therapy for children with Down's syndrome. Therefore, this therapy is widely applicable. In the treatment of children, it is indispensible to strictly follow application parameters and observe specifications concerning the size of the area that is exposed to treatment.Conclusions
Magnetoledtherapy is a valuable complement to the comprehensive rehabilitation of children and should be recommended for a wider application.
Saccharina japonica is a brown alga that has been commercially cultured on a large scale in China. Integrating the light condition under seawater
and the adaptation of Saccharina to this condition, it is expected that blue light would be beneficial to Saccharina culture system. Consequently, the detailed effect of blue light on the key stages during indoor seedling culture of S. japonica was investigated in this study. Irradiances and light qualities had little effect on zoospore attachment and germination.
Egg formation occurred sooner under blue light than white light. Under optimum irradiances, 95 ± 4% female gametophytes gave
rise to eggs in 6 d under blue light, while it took 12 d for over 90% formation of eggs under white light. Over a culture
period of 3weeks, mean sporeling length and width under blue light was 1.39 and 1.56 times of that under white light, respectively,
while the mean sporeling size obtained under red light was only 25% of that under white light. The higher growth rate under
blue light was largely due to higher photosynthetic efficiency, as indicated by chlorophyll fluorescence of photosystem II.
In addition, the mean ratio of sporeling width to length under blue light was significantly higher than that under white light.
These results suggest that blue light would be superior to white light for indoor seedling culture of S. japonica. Based on these findings, an improved S. japonica seedling culture system is discussed.
KeywordsChlorophyll fluorescence-Gametophyte-Photosynthesis-Sporophyte-Zoospore
Blue-light light-emitting diode (LED) therapy has become widely used for the treatment of inflammatory acne. In this study we evaluated the efficacy of a home use blue-light LED application in improving lesions and shortening their time to clearance.
This was an IRB approved randomized self-control study. For each patient (n = 30), 2 similar lesions, one of each side of the face were chosen for treatment with either a blue-light LED hand-held or sham device. Treatments (n = 4) were conducted twice daily in the clinic and lesions were followed-up till resolution. Reduction in blemishes size and erythema and the overall improvement were evaluated by both the physician and the patients. Time to lesion resolution was recorded.
There was a significant difference in the response of lesions to the blue-light LED application as opposed to the placebo in terms of reduction in lesion size and lesion erythema as well as the improvement in the overall skin condition (p < 0.025). Signs of improvement were observed as early as post 2 treatments. Time to resolution was significantly shorter for the blue-light LED therapy.
The results support the effectiveness of using blue-light LED therapy on a daily basis for better improvement and faster resolution of inflammatory acne lesions.
First commercially introduced in 1990, AlGaInP light emitting
diodes (LEDs) currently are the highest (luminous) efficiency visible
solid-state emitters produced to date in the red through yellow spectral
regime. The attainment of this high-efficiency performance is a result
of the development of advanced metalorganic chemical vapor deposition
crystal growth techniques, which have facilitated the high-quality
growth of this quaternary alloy as well as the implementation of complex
device designs. Furthermore, the highest efficiency family of AlGaInP
devices (based upon a transparent-substrate platform and commercially
introduced in 1994) have been realized as result of the development and
implementation of direct compound semiconductor wafer bonding
technology. As a result, the luminous efficiency of AlGaInP LEDs exceeds
or rivals that of unfiltered incandescent lamps and other conventional
lighting sources. Further improvements in these techniques (and the
realization of efficient, high-power LEDs) are expected to make AlGaInP
LEDs even more competitive with conventional lamp technology, thus
enhancing the position of LED's in many applications as a preferred
lighting source
Uniform current spreading is desirable for both light emitting diodes (LEDs) performance and reliability. It enhances optical efficiency because the joule losses due to current crowding in some parts of the die would be eliminated. The LED design for optimal light extraction and uniform current spreading is therefore a necessity. In this paper we report on preliminary current spreading results obtained from circuit simulation, using Pspice and Aimspice, for LED designs with and without an n-metal ring as well as the epi-up and flip chip LEDs. For the epi-up, both the lateral and vertical resistances of the transparent metals were taken into account. Whereas in the flip chip, the lateral resistance was negligibly small thus only the vertical component contributed to the total p-lump resistance. The n-lateral resistance in the active mesa was critical to uniform current spreading. It was found that the lower the n-lateral resistance, the more uniform the current spreads and flows through the active region. In both the epi-up and flip-chip structures, the contact resistance of the p-metal (including the thin Ni/Au transparent metal) dominated the total p-lump resistance. The larger this value, with fixed n-layer lateral resistance, the more uniform the current spreads in the device. However, high p- contact resistance is not desirable as it reduces the overall efficiency of the device due to excessive heating and increased leakage current. Therefore, for uniform current spreading, the n-lateral resistance should be made small while maintaining an optimum p-lump resistance to achieve a high efficiency.
Background and Objective
The effects of low-level laser light irradiation are still highly contested, and the mechanisms of its action still unclear. This study was conducted to test the effects of low-level laser irradiation at 660 nm on human lymphocytes and to investigate the possible mechanisms by which these effects are produced.Study Design/Materials and Methods
Whole blood obtained by phlebotomy was irradiated at 660 nm by using energy fluences between 0 and 5.0 J/cm2. The lymphocytes were isolated after irradiation of the whole blood. For the control experiment, the lymphocytes were first isolated and then irradiated at the same wavelength and energy fluence for comparison. The proliferation of lymphocytes and the formation of free radicals and lipid peroxides were monitored. Hemoglobin was also irradiated in a cell-free environment to test for the production of lipid peroxides.ResultsLymphocyte proliferation was significantly higher (P < 0.05) as expressed by a Stimulation Index in samples irradiated in the presence of whole blood compared with lymphocytes irradiated after isolation from whole blood. Free radical and lipid peroxide production also increased significantly when samples were irradiated in the presence of red blood cells.Conclusion
The present study supports the hypothesis that one mechanism for the photobiostimulation effect after irradiation at 660 nm is the reaction of light with hemoglobin, resulting in oxygen radical production. Lasers Surg. Med. 27:255–261, 2000 © 2000 Wiley-Liss, Inc.
Background and Objective
Low-level laser irradiation at certain fluences and wavelengths can enhance the release of growth factors from fibroblasts and stimulate cell proliferation in vitro. We evaluated whether low-level laser irradiation can improve wound healing in diabetes mellitus.Study Design/Materials and Methods
Genetically diabetic mice (C57BL/Ksj/db/db) were used as the animal model for this wound healing study. The experimental animals were divided among four groups: negative control, positive control (topical basic fibroblast growth factor [bFGF] on wound), laser therapy group; and a combination group of laser therapy and topical bFGF. An argon dye laser (Lexel Auora Model 600) at a wavelength of 630 nm and an output of 20 mW/cm2 was used as the light source. The speed of wound closure and histological evaluation were used to analyze the experimental results.ResultsLaser irradiation enhanced the percentage of wound closure over time as compared to the negative control group (58.4 ± 2.6 vs. 40.8 ± 3.4 at day 10 and 95.7 ± 2 vs. 82.3 ± 3.6 at day 20, P < .01). Histological evaluation showed that laser irradiation improved wound epithelialization, cellular content, granulation tissue formation, and collagen deposition in laser-treated wounds as compared to the negative control group (6.4 ± 0.16 vs. 3.8 ± 0.13 at day 10 and 12 ± 0.21 vs. 8.2 ± 0.31, P < .01).Conclusion
This study of laser biostimulation on wound healing in diabetic mice suggests that such therapy may be of great benefit in the treatment of chronic wounds that occur as a complication of diabetes mellitus. Lasers Surg Med 20:56–63, 1997. © 1997 Wiley-Liss, Inc.
Objective
We tested the hypothesis that combined 660 and 890 nm LED phototherapy will promote healing of diabetic ulcers that failed to respond to other forms of treatment.Research Design and MethodsA double-blind randomized placebo controlled design was used to study 23 diabetic leg ulcers in two groups of 14 patients. Group one ulcers were cleaned, dressed with 1% silver sulfadiazine cream and treated with “placebo” phototherapy (<1.0 J cm−2) twice per week, using a Dynatron Solaris 705® device. Group two ulcers were treated similarly but received 3 J cm−2 dose.ResultsAt each of 15, 30, 45, 60, 75, and 90 days of healing, mean ulcer granulation and healing rates were significantly higher for group two than the “placebo” group (P < 0.02). While “placebo” treated ulcers worsened during the initial 30 days, group two ulcers healed rapidly; achieving 56% more granulation and 79.2% faster healing by day 30, and maintaining similarly higher rates of granulation and healing over the “placebo” group all through. By day 90, 58.3% of group two ulcers had healed fully and 75% had achieved 90–100% healing. In contrast, only one “placebo” treated ulcer healed fully by day 90; no other ulcer attained ≥90% healing.Conclusion
Combined 660 and 890 nm light promotes rapid granulation and healing of diabetic ulcers that failed to respond to other forms of treatment. Lasers Surg. Med. 41:433–441, 2009. © 2009 Wiley-Liss, Inc.
Pain is the main acute adverse event during photodynamic therapy of skin lesions. The objective of this randomized study was to evaluate the pain-relieving effect of pauses and cooling during illumination. Twenty-four patients with actinic keratoses were treated with photodynamic therapy in two symmetrical areas and cooled with either cold-water-spray or cold-water-pack (CoolPack). Treatment areas were cooled during either the first or second period of illumination, which were separated by a 3-min pause in illumination. Pain intensity was scored from 0 to 10. Water-spray reduced the mean pain score by 1.2 points (p=0.030) and CoolPack by 1.3 points (p=0.007) during the first half of the illumination. Pain intensity decreased during the pause by 3.7 points in water-spray patients (p<0.0001) and 3.0 points in CoolPack patients (p<0.0001). In conclusion, cooling resulted in a minor reduction in pain intensity, while adding the intermediate pause in illumination reduced the pain considerably. Use of pauses and cooling during illumination is an easy and inexpensive way to make photodynamic therapy more tolerable for the patient.
The purpose of this study was to assess the changes in gene expression of near-infrared light therapy in a model of impaired wound healing. Background Data: Light-Emitting Diodes (LED), originally developed for NASA plant growth experiments in space, show promise for delivering light deep into tissues of the body to promote wound healing and human tissue growth. In this paper we present the effects of LED treatment on wounds in a genetically diabetic mouse model.
Polyvinyl acetal (PVA) sponges were subcutaneously implanted in the dorsum of BKS.Cg-m +/+ Lepr(db) mice. LED treatments were given once daily, and at the sacrifice day, the sponges, incision line and skin over the sponges were harvested and used for RNA extraction. The RNA was subsequently analyzed by cDNA array.
Our studies have revealed certain tissue regenerating genes that were significantly upregulated upon LED treatment when compared to the untreated sample. Integrins, laminin, gap junction proteins, and kinesin superfamily motor proteins are some of the genes involved during regeneration process. These are some of the genes that were identified upon gene array experiments with RNA isolated from sponges from the wound site in mouse with LED treatment.
We believe that the use of NASA light-emitting diodes (LED) for light therapy will greatly enhance the natural wound healing process, and more quickly return the patient to a preinjury/illness level of activity. This work is supported and managed through the Defense Advanced Research Projects Agency (DARPA) and NASA Marshall Space Flight Center-SBIR Program.
Photomodulation is a process that manipulates or regulates cell activity using light sources without thermal effect. Previous studies of LED photomodulation have shown skin textural improvement accompanied by increased collagen deposition with reduced MMP-1 (collagenase) activity in the papillary dermis. The purpose of this study was to investigate a separate cohort of patients (N =93) with a wide range of Fitzpatrick skin types treated by LED photomodulation using the Gentlewaves full panel 590 nm high energy LED array with a specific sequence or code of pulsing in the millisecond domain. Results showed improvement of signs of photoaging in 90%. The majority of patients demonstrated improvement in peri-ocular wrinkles, reduction in Fitzpatrick photoaging classification, global skin texture and background erythema, and pigmentation. No side effects were noted. LED photomodulation is a safe and effective non-painful non-ablative modality for improvement of photoaging.
The chronic metabolic disorder diabetes mellitus is an important cause of morbidity and mortality due to a series of common secondary metabolic complications, such as the development of severe, often slow healing skin lesions. In view of promoting the wound-healing process in diabetic patients, this preliminary in vitro study investigated the efficacy of green light emitting diode (LED) irradiation on fibroblast proliferation and viability under hyperglycemic circumstances.
To achieve hyperglycemic circumstances, embryonic chicken fibroblasts were cultured in Hanks' culture medium supplemented with 30 g/L glucose. LED irradiation was performed on 3 consecutive days with a probe emitting green light (570 nm) and a power output of 10 mW. Each treatment lasted 3 min, resulting in a radiation exposure of 0.1 J/cm2.
A Mann-Whitney U test revealed a higher proliferation rate (p = 0.001) in all irradiated cultures in comparison with the controls.
According to these results, the effectiveness of green LED irradiation on fibroblasts in hyperglycemic circumstances is established. Future in vivo investigation would be worthwhile to investigate whether there are equivalent positive results in diabetic patients.
In this paper we use Aimspice device and circuit simulator to demonstrate that uniform current spreading does not only depend on p-transparent metal and n-GaN layers resistivities but is also a strong function of design. This is demonstrated by modeling two light emitting diode (LED) designs, A and B, which differ in the position and size of the p-contact pad. Design A exhibited better current uniformity than B because of the symmetry in the current spreading length. By keeping the resistivities of p-transparent metal and n-GaN layers fixed, the variation in current uniformity as bias current increases from 20 to 300 mA for design A is only 2% and ∼9.5% for design B. The decrease in current spreading uniformity as the resistances of these layers increase is smaller in design A (2–3.5% as resistance increases from 3.8 to 6.7 ) than design B (9.5–14.5%). A further analysis shows that the current uniformity increases as the p-transparent metal layer resistance decreases from 25 to 3.8 , even though, the n-GaN lateral resistance is fixed at 12 . This suggests better uniform current spreading in flipped chip LED design than top-emitting light emitting diodes, since LED flipped chip configuration uses thick reflective metal on top of p_GaN. Further more, current spreading uniformity increases as the thickness of p-transparent metal layer and in this model it peaked at 94.9% for a thickness of 15 nm. This is where the contact resistance, which dominates the vertical resistance of the network, had the highest value. It therefore means that the current uniformity is a function of contact resistance, which is based on the thickness of the transparent metal and ultimately affects light extraction.
Two portable light sources, comprising light emitting diodes (LEDs) of two different wavelengths, were compared to a standard light box in suppressing and phase shifting nocturnal salivary melatonin. All light sources were equated for illuminance of 2000 lux. Sixty-six volunteers participated in the 2-day study and were randomly allocated to one of four conditions; light box, white LED, blue/green LED, or no light control group. Light was administered to the experimental groups from midnight to 02.00 hr on the first night. Half-hourly saliva samples were collected from 19.00 to 02.00 hr on night 1 and until 01.00 hr on night 2. Percent melatonin suppression on night 1 and dim light melatonin onset (DLMO) for each night were calculated. The experimental groups showed significant melatonin suppression during light stimulation, with the blue/green LEDs producing the greatest (70%) suppression. There was no significant difference between the light box at 63% and white LED at 50% suppression. Similarly, the blue/green LED had a significantly greater DLMO delay of 42 min and no difference between the light box of 23 min and the white LED of 22 min. These data suggest the portable LED light source is an effective way of delivering light to phase shift the melatonin rhythm, with the blue/green LED being the more effective of the two LEDs.
Electrical and optical properties of Nichia double‐heterostructure blue light‐emitting diodes, with In 0.06 Ga 0.94 N:Zn, Si active layer, are investigated over a wide temperature range from 10 to 300 K. Current–voltage characteristics have complex character and suggest the involvement of various tunneling mechanisms. At small voltages (and currents), the peak wavelength of the optical emission shifts with the applied bias across a large spectral range from 539 nm (2.3 eV) up to 443 nm (2.8 eV). Light emission takes place even at the lowest temperatures, indicating that a complete carrier freeze‐out does not occur. © 1996 American Institute of Physics.
The most common side effects of fractional laser skin treatment are erythema and edema. Low-level light therapy and light-emitting diode (LED) devices have been used to stimulate fibroblast activity and hasten wound healing.
To determine whether LED treatment immediately after fractional laser skin resurfacing affects the severity and duration of postoperative eythema.
Twenty patients received treatment with a 590-nm wavelength LED array to randomly selected facial halves immediately after undergoing full-face fractional laser skin resurfacing with a 1,550-nm erbium-doped fiber laser. Differences in erythema between LED-treated and untreated facial halves were recorded at 24, 48, and 96 hours post-treatment.
The LED-treated facial halves were less erythematous in all 20 patients 24 hours postoperatively. The six patients who received the highest mean energy densities during fractional laser treatment continued to exhibit decreased erythema in the LED-treated areas at 48 hours. At 96 hours post-treatment, no discernible differences between facial halves were observed in any patient.
Photomodulation with a 590-nm-wavelength LED array can decrease the intensity and duration of postfractional laser treatment erythema.
Photodynamic therapy (PDT) is an effective treatment for actinic keratoses (AKs). Light-emitting diodes (LEDs) offer practical advantages when treating multiple lesions.
To evaluate the efficacy and tolerability of PDT using a LED and topical methyl aminolevulinate (MAL) for treatment of multiple AKs.
One hundred thirty-one patients with four to 10 non-pigmented, previously untreated thin or moderately thick AKs on the face or scalp were enrolled in this multicenter, double-blind, randomized, placebo-controlled study. MAL or matching placebo cream was applied to the débrided lesion surface for 3 hours before illumination with noncoherent red light (630 nm, light dose 37 J/cm(2)). Treatment was repeated 1 week later.
Efficacy was evaluated in 57 patients with 418 lesions treated with MAL PDT and 58 with 414 lesions treated with placebo PDT. Sixteen patients were excluded as protocol violators (not randomized). MAL PDT was superior (p< .001) to placebo PDT in lesion complete response rates (83.3%, 95% confidence interval (CI)=79.3-86.7%, vs 28.7%, 95% CI=24.4-33.4%) and patient complete response rates (all lesions showing complete response; 68.4%, 95% CI=54.8-80.1% vs 6.9%, 95% CI=1.9-16.7%).
Topical MAL PDT using a LED is an effective treatment for multiple AKs.
A light-emitting diode (LED) photomodulation system can produce pulses of amber light expected to induce structural skin changes and reverse the effects of photoaging.
To reproduce the encouraging results already published.
Facial skin was exposed to pulses of 588+/-10-nm-wavelength light from a photomodulation device for 40 seconds once a week for 8 weeks. Photographs, clinical assessment, and a subjective questionnaire were taken at baseline, at the last follow-up, and 1 month after that. Thirty-six patients' pre- and post-treatment photos were arbitrarily scrambled, and 30 independent blinded observers were asked to pick the post-treatment photo. Two time-point comparisons were evaluated.
For every facial characteristic studied and for both time-point comparisons, patients reported highly statistically significant improvements. In extremely sharp contrast, neither the physician's assessment nor the independent observers' evaluation indicated any improvement.
Although subjective findings are comparable between studies, we were unable to reproduce the objective results of efficacy previously reported. Patients genuinely believed that several of their facial features had improved, even though there was no detectable objective change. Our data therefore suggest that the LED photomodulation treatment from the device tested is a placebo.
Chronic wounds resistant to conventional therapy have been treated successfully with low energy lasers and light emitting diodes (LEDs) in the visible and near IR region. It has been proposed that production of low level reactive oxygen species (ROS) following illumination is the first step of photobiomodulation. It was also shown that white light (400-800 nm) has similar stimulatory effects as lasers and LEDs. ROS at higher levels are toxic to cells and bacteria.
In the present study, we examined the phototoxicity of broadband (400-800 nm, 120 J/cm(2)) visible light on the survival of several pathogenic bacteria: Staphylococcus aureus 195, Pseudomonas aeruginosa 1316, Escherichia coli 1313, and Serratia marcescens. These bacteria were chosen due to their high prevalence in infected wounds. The survival of bacterial cells following illumination was monitored by counting the number of colony forming units before and after exposure to light.
Illumination with white light, 120 J/cm(2), caused a reduction of 62%, 83%, and 56% in the colony count of E. coli 1313, S. aureus 195 and S. marcescens, respectively, though no reduction in the viability of P. aeruginosa 1316 was demonstrated. The phototoxic effect was found to involve induction of ROS production by the bacteria. It was also found that illumination of S. aureus 195 and E. coli 1313 in the presence of pyocyanin, known to be secreted by P. aeruginosa, had a stronger bactericidal effect compared to illumination alone.
Visible light at high intensity can kill bacteria in infected wounds. Thus, illumination of infected wounds with intense visible light, prior to low intensity illumination for stimulating wound closure, may reduce infection and promote healing.
—Propionibacterium acnes (P. acnes), grown on Eagles medium with different pH. were irradiated with monochromatic light in the range 320 to 440 nm. Different pH leads to different porphyrin concentrations in the cells. The light sensitivity of the bacteria was estimated from the reduction in their ability to form colonies after radiation. The sensitivity was highest for the lowest wavelength (320 nm). and decreased continuously with increasing wavelength up to 380 nm. In the region between 380 and 440 nm there was a second maximum (at 415 nm) which corresponds to the maximum absorption ol the fluorescing porphyrins in P. acnes. The sensitivity to 415 nm light was found to be dependent on the endogenous porphyrin concentration in the cells. while the sensitivity to 320 nm radiation was independent of the amount of porphyrin present. These results indicate that porphyrins produced by the bacteria are important for the light sensitivity of these bacteria.
Propionibacterium acnes cells were tested for the ability to trigger lysosomal hydrolase release from human polymorphonuclear leukocytes. Representative strains of P. acnes serotype I and II failed to stimulate lysosomal release in the absence of serum. P. acnes growth culture supernatants failed to trigger release under any test condition. Addition of fresh or heat-inactivated human serum resulted in lysosomal hydrolase release directly proportional to the number of P. acnes/PMN. Pooled sera from acne patients, with a high anti-P. acnes titer stimulated release to P. acnes. Preabsorption of this reagent with P. acnes cells reduced the anti-P. acnes titer and produced 93.37 +/- 11.49% inhibition of lysosomal enzyme release compared to unabsorbed anti-serum. Electron microscopy indicated that P. acnes was readily phagocytosed by PMNs when fresh or heated serum was present.
Studies have shown that low-level laser irradiation increases the proliferation of fibroblasts in cell culture. The mechanism of action is unknown. Basic fibroblast growth factor (bFGF) is a multifunctional polypeptide that has been detected in most tissues and which supports cell proliferation and differentiation. The purpose of this study was to determine whether laser irradiation (660 nm) can stimulate production of bFGF from fibroblast cells in cell culture. Our study showed that fibroblasts irradiated with laser energy at 2.16 J/cm2 demonstrated increased cell proliferation and enhanced production of bFGF, whereas fibroblasts irradiated with laser energy at 3.24 J/cm2 neither demonstrated increased cell proliferation or an enhanced release of bFGF as compared to the control group. These results provide direct evidence that the proliferation of fibroblasts as a result of stimulation by low level laser irradiation may be associated with the autocrine production of bFGF from fibroblasts.
In this study we have evaluated the use of blue light (peak at 415 nm) and a mixed blue and red light (peaks at 415 and 660 nm) in the treatment of acne vulgaris. One hundred and seven patients with mild to moderate acne vulgaris were randomized into four treatment groups: blue light, mixed blue and red light, cool white light and 5% benzoyl peroxide cream. Subjects in the phototherapy groups used portable light sources and irradiation was carried out daily for 15 min. Comparative assessment between the three light sources was made in an observer-blinded fashion, but this could not be achieved for the use of benzoyl peroxide. Assessments were performed every 4 weeks. After 12 weeks of active treatment a mean improvement of 76% (95% confidence interval 66-87) in inflammatory lesions was achieved by the combined blue-red light phototherapy; this was significantly superior to that achieved by blue light (at weeks 4 and 8 but not week 12), benzoyl peroxide (at weeks 8 and 12) or white light (at each assessment). The final mean improvement in comedones by using blue-red light was 58% (95% confidence interval 45-71), again better than that achieved by the other active treatments used, although the differences did not reach significant levels. We have found that phototherapy with mixed blue-red light, probably by combining antibacterial and anti-inflammatory action, is an effective means of treating acne vulgaris of mild to moderate severity, with no significant short-term adverse effects.
Topical aminolevulinic acid is converted into a potent photosensitizer, protoporphyrin, in human hair follicles and sebaceous glands. Photodynamic therapy with topical aminolevulinic acid was tested for the treatment of acne vulgaris, in an open-label prospective human study. Each of 22 subjects with acne on the back was treated in four sites with aminolevulinic acid plus red light, aminolevulinic acid alone, light alone, and untreated control. Half of the subjects were treated once; half were treated four times. Twenty percent topical aminolevulinic acid was applied with 3 h occlusion, and 150 J per cm2 broad-band light (550-700 nm) was given. Sebum excretion rate and auto-fluorescence from follicular bacteria were measured before, and 2, 3, 10, and 20 wk after, treatment. Histologic changes and protoporphyrin synthesis in pilosebaceous units were observed from skin biopsies. Aminolevulinic acid plus red light caused a transient acne-like folliculitis. Sebum excretion was eliminated for several weeks, and decreased for 20 wk after photodynamic therapy; multiple treatments caused greater suppression of sebum. Bacterial porphyrin fluorescence was also suppressed by photodynamic therapy. On histology, sebaceous glands showed acute damage and were smaller 20 wk after photodynamic therapy. There was clinical and statistically significant clearance of inflammatory acne by aminolevulinic acid plus red light, for at least 20 wk after multiple treatments and 10 wk after a single treatment. Transient hyperpigmentation, superficial exfoliation, and crusting were observed, which cleared without scarring. Topical aminolevulinic acid plus red light is an effective treatment of acne vulgaris, associated with significant side-effects. Aminolevulinic acid plus red light causes phototoxicity to sebaceous follicles, prolonged suppression of sebaceous gland function, and apparent decrease in follicular bacteria after photodynamic therapy. Potentially, aminolevulinic acid plus red light may be useful for some patients with acne.
The effects of low-level laser light irradiation are still highly contested, and the mechanisms of its action still unclear. This study was conducted to test the effects of low-level laser irradiation at 660 nm on human lymphocytes and to investigate the possible mechanisms by which these effects are produced.
Whole blood obtained by phlebotomy was irradiated at 660 nm by using energy fluences between 0 and 5.0 J/cm(2). The lymphocytes were isolated after irradiation of the whole blood. For the control experiment, the lymphocytes were first isolated and then irradiated at the same wavelength and energy fluence for comparison. The proliferation of lymphocytes and the formation of free radicals and lipid peroxides were monitored. Hemoglobin was also irradiated in a cell-free environment to test for the production of lipid peroxides.
Lymphocyte proliferation was significantly higher (P<0.05) as expressed by a Stimulation Index in samples irradiated in the presence of whole blood compared with lymphocytes irradiated after isolation from whole blood. Free radical and lipid peroxide production also increased significantly when samples were irradiated in the presence of red blood cells.
The present study supports the hypothesis that one mechanism for the photobiostimulation effect after irradiation at 660 nm is the reaction of light with hemoglobin, resulting in oxygen radical production.
The purpose of this study was to assess the effects of hyperbaric oxygen (HBO) and near-infrared light therapy on wound healing.
Light-emitting diodes (LED), originally developed for NASA plant growth experiments in space show promise for delivering light deep into tissues of the body to promote wound healing and human tissue growth. In this paper, we review and present our new data of LED treatment on cells grown in culture, on ischemic and diabetic wounds in rat models, and on acute and chronic wounds in humans.
In vitro and in vivo (animal and human) studies utilized a variety of LED wavelength, power intensity, and energy density parameters to begin to identify conditions for each biological tissue that are optimal for biostimulation. Results: LED produced in vitro increases of cell growth of 140-200% in mouse-derived fibroblasts, rat-derived osteoblasts, and rat-derived skeletal muscle cells, and increases in growth of 155-171% of normal human epithelial cells. Wound size decreased up to 36% in conjunction with HBO in ischemic rat models. LED produced improvement of greater than 40% in musculoskeletal training injuries in Navy SEAL team members, and decreased wound healing time in crew members aboard a U.S. Naval submarine. LED produced a 47% reduction in pain of children suffering from oral mucositis.
We believe that the use of NASA LED for light therapy alone, and in conjunction with hyperbaric oxygen, will greatly enhance the natural wound healing process, and more quickly return the patient to a preinjury/illness level of activity. This work is supported and managed through the NASA Marshall Space Flight Center-SBIR Program.
Photomodulation has been described as a process which modifies cell activity using light sources without thermal effect. The objective of this study was to investigate the use of a non-thermal low dose light emitting diode (LED) array for improving the appearance of photoaged subjects.
This prospective study investigated a random cohort of patients (N = 90) with a wide range of photoaged skin treated by LED photomodulation using a full panel 590 nm non-thermal full face LED array delivering 0.1 J/cm(2) with a specific sequence of pulsing. Subjects were evaluated at 4, 8, 12, 18 weeks and 6 and 12 months after a series of 8 treatments delivered over 4 weeks. Data collected included stereotactic digital imaging, computerized optical digital profilometry, and peri-ocular biopsy histologic evaluations for standard stains and well as collagen synthetic and degradative pathway immunofluorescent staining.
Digital imaging data showed a reduction of signs of photoaging in 90% of subjects with smoother texture, reduction of peri-orbital rhytids, and reduction of erythema and pigmentation. Optical profilometry showed a 10% improvement by surface topographical measurements. Histologic data showed markedly increased collagen in the papillary dermis of 100% of post-treatment specimens (N = 10). Staining with anti-collagen I antibodies demonstrated a 28% (range: 10%-70%) average increase in density while staining with anti-matrixmetalloproteinase (MMP)-1 showed an average reduction of 4% (range: 2%-40%). No side effects or pain were noted.
Photomodulation to reverse photoaging is possible with a specific array of LEDs with a specific fluence using a precise pulsing or "code" sequence. Skin textural improvement by digital imaging and surface profilometry is accompanied by increased collagen I deposition with reduced MMP-1 (collagenase) activity in the papillary dermis. This technique is a safe and effective non-painful non-ablative modality for improvement of photoaging.
The effective management of acne remains a challenge; achieving an optimal response whilst minimizing adverse events is often difficult. The rise in antibiotic resistance threatens to reduce the future usefulness of the current mainstay of therapy. The need for alternative therapies remains important. Phototherapy has previously been shown to be effective in acne, with renewed interest as both endogenous and exogenous photodynamic therapies are demonstrated for this condition.
To determine the effect of narrowband blue light in the reduction of inflammatory and non-inflammatory lesions in patients with mild to moderate acne and to evaluate patient tolerance of the therapy.
We performed an open study utilizing a blue LED light source in 30 subjects with mild to moderate facial acne. Two weeks after screening, lesions were counted and recorded by lesion type. Over 4 weeks, patients received eight 10- or 20-minute light treatments, peak wavelength 409-419 nm at 40 mW/cm2. Assessments were taken at weeks 5, 8 and 12 and lesion counts were recorded. Repeated measures-ANOVA and Dunnett's tests, respectively, allowed assessment of the different scores over time and permitted comparison of mean counts.
An overall effect on inflammatory counts was observed at week 5, and a statistically significant decrease in inflamed counts was detected at the week 8 assessments, which continued to week 12. There was little effect on non-inflamed lesions. The treatment was well tolerated with adverse events experienced generally rated as being mild and usually self-limiting.
Eight 10- or 20-minute treatments over 4 weeks with a narrowband blue light was found to be effective in reducing the number of inflamed lesions in subjects with mild to moderate acne. The treatment had little effect on the number of comedones. The onset of the effect was observable at the first assessment, at week 5, and maximal between weeks 8 and 12. Blue light phototherapy using a narrowband LED light source appears to be a safe and effective additional therapy for mild to moderate acne.
Blue light is effective for acne treatment, inducing photodynamic destruction of Propionibacterium acnes (P. acnes). This study was designed to investigate the efficacy of combined blue and red light-emitting diode (LED) phototherapy for acne vulgaris.
Twenty-four patients with mild to moderately severe facial acne were treated with quasimonochromatic LED devices, alternating blue (415 nm) and red (633 nm) light. The treatment was performed twice a week for 4 weeks. Objective assays of the skin condition were carried out before and after treatment at each treatment session. Clinical assessments were conducted before treatment, after the 2nd, 4th, and 6th treatment sessions and at 2, 4, and 8 weeks after the final treatment by grading and lesion counting.
The final mean percentage improvements in non-inflammatory and inflammatory lesions were 34.28% and 77.93%, respectively. Instrumental measurements indicated that the melanin levels significantly decreased after treatment. Brightened skin tone and improved skin texture were spontaneously reported by 14 patients.
Blue and red light combination LED phototherapy is an effective, safe and non-painful treatment for mild to moderately severe acne vulgaris, particularly for papulopustular acne lesions.
Light-emitting diode (LED) photomodulation increases dermal collagen and reduces inflammation. This study evaluated the use of LED photomodulation in the prevention of radiation-induced dermatitis in breast cancer.
Patients (n=19) were treated with LED photomodulation (Gentlewaves, Light BioScience, LLC, Virginia Beach, VA) after each of a series of intensity-modulated radiation treatments (IMRT). Skin reactions were monitored weekly with National Cancer Institute (NCI) criteria. Age-matched controls (n=28) received IMRT without LED photomodulation.
In LED-treated patients, 18 (94.7%) had grade 0 or 1 reaction and 1 (5.3%) had grade 2 reaction. Among controls, 4 (14.3%) had a grade 1 reaction, 24 (85.7%) had a grade 2 or 3 reaction. One LED-treated patient (5.3%) and 19 controls (67.9%) had to interrupt treatment.
LED photomodulation treatments immediately after IMRT reduces the incidence of NCI grades 1, 2, and 3 skin reactions in patients with breast cancer treated by radiation therapy (RT) postlumpectomy.
The role of radiotherapy in ophthalmic practice continues to grow. This growth has seen an expansion of indications for radiotherapy, a refinement of the modalities that can be used and a reduction in the ocular and adnexal complications that result from this form of therapy. The compendium of indications for radiotherapy in ophthalmology continues to grow and now includes many conditions such as the treatment of lid and adnexal disease, ocular surface disorders and both benign and malignant disease of the posterior segment and optic pathways. The radiotherapeutic modalities employed to manage these conditions are numerous and include both radioactive plaques (brachytherapy) and external beam radiation techniques. New techniques such as stereotactic radiosurgery are delivering benefits in the management of conditions such as optic nerve sheath meningioma, where the treatment of this blinding and occasionally life-threatening intracranial neoplasm now results in fewer adverse affects. The purpose of this review is to give a brief overview of the indications and treatment modalities, and a more in-depth discussion of the potential side-effects when radiotherapy is used for ocular and periorbital disease.
Light-emitting diodes (LEDs) are considered to be effective in skin rejuvenation. We investigated the clinical efficacy of LED phototherapy for skin rejuvenation through the comparison with three different treatment parameters and a control, and also examined the LED-induced histological, ultrastructural, and biochemical changes. Seventy-six patients with facial wrinkles were treated with quasimonochromatic LED devices on the right half of their faces. All subjects were randomly divided into four groups treated with either 830nm alone, 633nm alone, a combination of 830 and 633nm, or a sham treatment light, twice a week for four weeks. Serial photography, profilometry, and objective measurements of the skin elasticity and melanin were performed during the treatment period with a three-month follow-up period. The subject's and investigator's assessments were double-blinded. Skin specimens were evaluated for the histologic and ultrastructural changes, alteration in the status of matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs), and the changes in the mRNA levels of IL-1ss, TNF-alpha, ICAM-1, IL-6 and connexin 43 (Cx43), by utilizing specific stains, TEM, immunohistochemistry, and real-time RT-PCR, respectively. In the results, objectively measured data showed significant reductions of wrinkles (maximum: 36%) and increases of skin elasticity (maximum: 19%) compared to baseline on the treated face in the three treatment groups. Histologically, a marked increase in the amount of collagen and elastic fibers in all treatment groups was observed. Ultrastructural examination demonstrated highly activated fibroblasts, surrounded by abundant elastic and collagen fibers. Immunohistochemistry showed an increase of TIMP-1 and 2. RT-PCR results showed the mRNA levels of IL-1ss, TNF-alpha, ICAM-1, and Cx43 increased after LED phototherapy whereas that of IL-6 decreased. This therapy was well-tolerated by all patients with no adverse effects. We concluded that 830 and 633nm LED phototherapy is an effective approach for skin rejuvenation.
Recent work suggests that injuries can heal faster if treated by lasers emitting 670-nm red light. LED lights emitting 670-nm light are now available. This suggests that inexpensive and easy-to-use 670-nm LED lights might help accelerate cutaneous wound healing.
The objective was to evaluate the effect of 670-nm LED light on wound healing in SKH-1 hairless mice.
To study 670-nm light effects on incisional injury, animals were left unexposed or exposed to equal doses of high-, medium-, or low-flux light. Burn injuries were treated with high-flux light or left unexposed. Healing was assessed by measurement of the burn area and the gap remaining to closure of incisional injury.
Mice exposed to 670-nm red light showed significantly faster healing than control mice. High, medium, and low fluxes of light were all effective after incisional injury. In burn injury, there was improvement in wound healing initially, but the time to repair was unchanged.
A 670-nm LED red light source accelerates healing in skin of SKH-1 hairless mice after incisional injuries, but is not as effective for burn injuries. These data that suggest red light exposure may be helpful in postoperative wound repair.
Introduction to Device modeling and circuit simulation
- T A Fjeldly
- T Ytterdal
- M Shur
T. A. Fjeldly, T. Ytterdal, M. Shur, "Introduction to Device modeling and circuit simulation", Wiley & Sons,
Inc.