Photo-biomodulatory response of low-power laser irradiation on burn tissue repair in mice.
- 1Department of Biophysics, School of Life Sciences, Manipal University, Manipal, 576104, India.
- 2Department of Radiation Biology and Toxicology, School of Life Sciences, Manipal University, Manipal, 576104, India.
- 3Department of Biotechnology, MIT, Manipal University, Manipal, 576104, India.
- 4Department of Pathology, KMC Mangalore, Manipal University, Mangalore, 576104, India.
- 5Department of Pathology, KMC Manipal, Manipal University, Manipal, 576104, India.
- 6Department of Pathology, Srinivas Institute of Medical Sciences and Research Centre, Surathkal, Mangalore, 575021, India.
- 7Laser Biomedical Applications and Instrumentation Division, RRCAT, Indore, 452013, India.
- 8Department of Biophysics, School of Life Sciences, Manipal University, Manipal, 576104, India. firstname.lastname@example.org.
The present work reports the photo-biomodulatory effect of red (632.8 nm) and near infrared (785 and 830 nm) lasers on burn injury in Swiss albino mice. Animals were induced with a 15-mm full thickness burn injury and irradiated with various fluences (1, 2, 3, 4, and 6 J/cm2) of each laser wavelength under study having a constant fluence rate (8.49 mW/cm2). The size of the injury following treatment was monitored by capturing the wound images at regular time intervals until complete healing. Morphometric assessment indicated that the group treated with 3-J/cm2 fluence of 830 nm had a profound effect on healing as compared to untreated controls and various fluences of other wavelengths under study. Histopathological assessment of wound repair on treatment with an optimum fluence (3 J/cm2) of 830 nm performed on days 2, 6, 12, and 18 post-wounding resulted in enhanced wound repair with migration of fibroblasts, deposition of collagen, and neovascularization as compared to untreated controls. The findings of the present study have clearly demonstrated that a single exposure of 3-J/cm2 fluence at 830-nm enhanced burn wound healing progression in mice, which is equivalent to 5 % povidone iodine treatment (reference standard), applied on a daily basis till complete healing.
Effects of low level laser therapy on the prognosis of split-thickness skin graft in type 3 burn of diabetic patients: a case series.
- 1Burn Research Center, Iran University of Medical Sciences, Tehran, Iran.
- 2Skin and Stem Cell Research Center, Tehran University of Medical Sciences, Tehran, Iran. email@example.com.
- 3Canadian Optic and Laser Center, Victoria, BC, Canada.
- 4Skin and Stem Cell Research Center, Tehran University of Medical Sciences, Tehran, Iran.
- 5Skin Diseases and Leishmaniasis Research Center, Isfahan University of Medical Sciences, Isfahan, Iran.
Significant populations in burn centers are diabetic burn patients. Healing process in these patients is more difficult due to diabetes complications. The gold standard treatment for patients with grade 3 burn ulcer is split-thickness skin grafting (STSG), but in the diabetic patients, the rate of graft failure and amputation is high due to impaired tissue perfusion. The technique of low level laser therapy (LLLT) improves tissue perfusion and fibroblast proliferation, increases collagen synthesis, and accelerates wound healing. The purpose of this case report is introducing a new therapeutic method for accelerating healing with better prognosis in these patients. The protocols and informed consent were reviewed according to the Medical Ethics, Board of Shahid Beheshti Medical Sciences (IR.SBMU.RAM.REC.13940.363). Diabetic type 2 patients with 13 grade 3 burn ulcers, candidate for amputation, were enrolled in the study. We used a 650-nm red laser light, 2 J/Cm for the bed of the ulcer and an 810-nm infrared laser light 6 J/Cm(2) for the margins along with intravenous laser therapy with a 660-nm red light, before and after STSG for treating grade 3 burn ulcers in 13 diabetic ulcers. The results of this study showed complete healing in the last 8 weeks for all patients who were candidates for amputation. In this case series, we present 13 cases of diabetic ulcer with type 3 burn wound, candidate for amputation, who healed completely using LLLT and STSG. This is the first time that these two techniques are combined for treatment of burn ulcer in diabetic patients. Using LLLT with STSG might be a promising treatment for burn victims especially diabetic patients.
Effects of red laser, infrared, photodynamic therapy, and green LED on the healing process of third-degree burns: clinical and histological study in rats.
The aim of this study was to evaluate the effects of red laser, infrared, photodynamic therapy, and green light-emitting diode (LED) on the healing process of skin burns through clinical and histopathologic analysis in rats. For this, 100 animals were randomly divided into five groups: G1-untreated control (CTR), G2-red laser (LVER), G3-infrared (LINF), G4-photodynamic therapy (PDT), and G5-green LED. Burn was induced on the dorsum of the rat and the treatment of the experimental groups was red light (10 J/cm2, 10 s, 40 mW, and ?660 nm), infrared (10 J/cm2, 10 s, 40 mW, and ?780 nm), green LED irradiation (60 J/cm2, 10 s, ?520, and 550 nm), and photodynamic therapy (10 J/cm2, 40 mW, and ?660 nm), the latter combined with methylene blue photosensitizer at concentration 0.5 ?g/mL. Applications were performed daily until day prior to sacrifice of the animal at 3, 7, 14, and 21 days with intraperitoneal anesthetic overdose. The specimens collected were clinically examined and soon after processed and stained with hematoxylin-eosin and Picrosirius for analysis under light and polarized light microscopy, respectively. Animals treated with LVER, LINF, PDT (p?<?0.001), and LED (p?<?0.05) stimulated production and maturation of collagen, and increased the consumption of food and water compared to the CTR (p?<?0.001). Laser ?660 nm and ?780 nm showed the largest wound reductions in all groups (p?=?0.001). In conclusion, red laser, infrared, photodynamic therapy, and green LED favored the healing process of third-degree burns in rats.
Effect of low-level laser therapy (660 nm) on the healing of second-degree skin burns in rats.
Department of Biosciences, Federal University of São Paulo, UNIFESP, SP, Brazil. firstname.lastname@example.org
The aim of this study was to investigate the effects of 660 nm laser on the healing of burn wounds made on the backs of rats. Thirty-two Wistar male rats were used. The animals were randomly distributed into 2 groups of 16 animals each: control group (burned rats without treatment) and laser-treated group (burned rats treated with laser therapy). Each group was divided into two different subgroups, euthanized in different periods (subgroup A: 7 days post-surgery and subgroup B: 14 days post-surgery). Histopathological analysis revealed a significant decrease in the necrotic area in the laser-treated group compared to the controls at days 7 and 14 post-injury. COX-2 positive cells were found in a strong pattern in the group submitted to laser therapy after 7 days. Regarding VEGF immunomarker, a significant VEGF immunoexpression was detected in the laser-exposed group after 14 days when compared to the negative control group. Taken together, our results demonstrate that laser therapy is able to promote skin repair of burned rats as a result of decreasing necrotic area and an up-regulation of COX-2 and VEGF immunoexpression.
Cosmet Laser Ther. 2011 Oct 7. [Epub ahead of print]
Effect of incoherent LED radiation on third-degree burning wounds in rats.
Abstract The main physiological characteristics in a burn process are the increase of the capillary permeability and the occurrence of edema and exudation. Light-emitting diode (LED) has been proposed as treatment of burning. This study investigated the effects of LED on the repair process of rat skin submitted to a third-degree burning. The lesions were produced on the dorsal surface of male Wistar rats. Animals were divided into 4 groups (n=6) as follows: L1 and L2 groups as LED-treated burned rats, and received LED therapy along 7 and 15 days with 48 h intervals, respectively; C1 and C2 groups as control, non-treated burned rats. A red LED (640 nm – 30 mW) operating with a fluence of 4 J/cm(2) was used. The wound area was measured daily after irradiation. Animals were euthanized at the 8(th) and 16th days after burning, and the wound fragment was submitted to histology. The inflammatory cells as well as the damaged area at the 8th day after burns were significantly lower for the LED-treated group when compared to control. Furthermore, the LED phototherapy effect on cellular migration was even more pronounced at the 16th day. Our results indicated that the treatment with a LED system was clearly effective in reducing the number of inflammatory cells and improving the healing process in an experimental model of third-degree burnings.
J Cosmet Laser Ther. 2011 Jul 20. [Epub ahead of print]
Effect of low level laser therapy (660nm) on the healing of second degree skin burns in rats.
Abstract The aim of this study was to investigate the effects of 660 nm laser on the healing of burn wounds made on the backs of rats. A total of 32 Wistar male rats were used. The animals were randomly distributed into 2 groups of 16 animals each: control group (burned rats without treatment) and laser treated group (burned rats treated with lasertherapy). Each group was divided into two different subgroups, euthanized in different periods (subgroup A: 7 days post-surgery and subgroup B: 14 days post-surgery). Histopathological analysis revealed a significant decrease in the necrosis area in the laser treated group comparing to the controls at days 7 and 14 post-injury. COX-2 positive cells were found in a strong pattern in group submitted to laser therapy after 7 days. Regarding VEGF immunomarker, a significant VEGF immunoexpression was detected in laser exposed group after 14 days when compared to negative control group. Taken together our results demonstrate that lasertherapy is able to promote skin repair of burned rats as a result of decreasing necrosis area and an up-regulation of COX-2 and VEGF immunoexpresion.
Photomed Laser Surg. 2011 Apr 1. [Epub ahead of print]
Effect of Low-Level Treatment with an 80-Hz Pulsed Infrared Diode Laser on Mast-Cell Numbers and Degranulation in a Rat Model of Third-Degree Burn.
Khoshvaghti A, Zibamanzarmofrad M, Bayat M.
1 Anatomy Department, Medical Faculty, Artesh University of Medical Sciences (AUMS) , Tehran, Iran .
Abstract Background Data: Low-level laser therapy (LLLT) has been reported to be capable of changing mast cell numbers and degranulation in experimental burns in rats.
Objective: We conducted a study of the influence of LLLT on mast cells in a rat model of third-degree burn.
Methods: In this study we divided 48 rats equally into two groups of 24 rats each. Third-degree burns were inflicted at three different locations on each rat in each group. The first burn site on rats in group I was treated with 890-nm pulsed laser, 75W peak, 80?Hz, 180?ns, average power 1mW, illuminated area 1?cm(2), 1?mW/cm(2), 856?sec, 0.924?J/cm(2). The second burn site on both groups of rats was treated with 0.2% nitrofurazone cream. Mast cell numbers and degranulation at each burn site on each group of rats were then assessed at 4, 8, 13, and 20 days after the infliction of burns.
Results: Analysis of variance on day 4 showed that the total numbers of mast cells were significantly lower at the laser-treated burn sites than at other burn sites on both groups of rats. On day 8 the total numbers of mast cells were again significantly lower at the laser-treated burn sites than at other burn sites, and on day 13, the numbers of both types 1 and 2 mast cells were significantly lower at the laser-treated burn sites than at other burn sites.
Conclusions: We conclude that LLLT can significantly decrease total numbers of mast cells during the proliferation and remodeling phases of healing in a rat model of third-degree burn.
Effect of photodynamic therapy on the healing of cutaneous third-degree-burn: histological study in rats.
The aim of this study was to conduct a histological assessment of the effect of photodynamic therapy (PDT) on the repairing of third-degree-burn wounds made on the backs of rats with a heated scalpel. Ninety-six rats were divided into groups: G1, control (n = 24), cold scalpel; G2, burned, heated scalpel (n = 24); G3, low-level laser therapy (LLLT) (n = 24), on burns; and G4, photodynamic therapy (PDT) (n = 24), toluidine-O blue (100 microg/ml) and LLLT treatment on burns. The laser (685 nm) was applied in continuous mode, 50 mW, 4.5 J/cm(2), contact mode at nine points (9 s/point). Eight animals in each group were killed at 3 days, 7 days or 14 days after surgery, and tissue specimens containing the whole wounded area were removed and processed for histological analysis; the results were statistically analyzed with Kruskal-Wallis and Dunn’s tests (P < 0.05). The results demonstrated significant differences between G2 and G3, and between G2 and G4, at both 3 days and 7 days, with regard to acute inflammation scores; G1 and G2 showed significant differences when compared with G4 at 3 days, with regard to neo-angiogenesis scores; G1 and G2 were statistically different from G3 and G4 at both 3 days and 7 days, with regard to re-epithelization scores; G2 showed statistically significant differences when compared with G3 and G4 with regard to collagen fiber scores at 7 days. LLLT and PDT acted as a biostimulating coadjuvant agent, balancing the undesirable effect of the burn on the wound healing process, acting mainly in the early healing stages, hastening inflammation and increasing collagen deposition.
Photomed Laser Surg. 2009 Dec;27(6):959-64.
Low-level laser therapy using 80-Hz pulsed infrared diode laser accelerates third-degree burn healing in rat.
Vasheghani MM, Bayat M, Dadpay M, Habibie M, Rezaei F.
Basic Sciences Department, Paramedical Faculty, Shahid Beheshti University, M.C., and Pathology Department, 501 Army Hospital, Tehran, Iran.
OBJECTIVE: To evaluate 80-Hz pulsed infrared diode low-level laser therapy (LLLT) for third-degree burn healing in rats.
BACKGROUND DATA: Review of the literature indicates that LLLT has a biostimulatory effect on wound healing, although no clear recommendation can be made yet.
METHODS: Forty-eight male rats were divided into groups 1 and 2. On day 0, three third-degree burns were made on the dorsum of each rat using steam. In group 1, the first burn was exposed to an 80-Hz pulsed 890-nm infrared diode laser at 0.396 J/cm2 three times a week. In group 2, the first burn was exposed to the inactivated laser. In both groups, the second burns were treated with topical application of nitrofurazone 0.2%, and third burns did not receive any treatment and were considered as control burns.Burns were clinically examined. The rats were treated for 8, 12, and 20 days in both groups. On days 8, 2, and 20, microbiological samples of burns were collected and analyzed. Data were analyzed using the chi-square method. RESULTS: The paired Student t-test showed that the wound closure rate of laser-treated burns (17.6+/-1.86 days) was significantly longer than that of the control burns (19.6+/-0.81 days) (p=0.007).The number of laser-treated burns that closed was significantly higher than controls. Chi-square tests showed that there was not significant difference between each microorganism (Staphylococcus epidermis, S. aureus and Pseudomonas aeruginosa). CONCLUSION: LLLT using an 80-Hz pulsed infrared diode laser accelerated third-degree burn healing in rat.
Photomed Laser Surg. 2009 Apr;27(2):269-72.
Visible lasers were better than invisible lasers in accelerating burn healing on diabetic rats.
Al-Watban FA, Zhang XY, Andres BL, Al-Anize A.
Laser Research Section, Biological and Medical Research Department, King Faisal Specialist Hospital and Research Centre, Riyadh, Kingdom of Saudi Arabia. email@example.com
OBJECTIVE: This study was designed to assess and compare the efficacy of accelerating burn healing in diabetic rats using low-power visible and invisible lasers. Background Data: Low-level laser therapy (LLLT) has been used in a number of diabetic animal and human studies, with both positive and no effects. MATERIALS AND METHODS: Male Sprague-Dawley rats were used in the study. Streptozotocin (70 mg/kg) was given for diabetes induction. A burn wound was created on the shaved back of the animals using a metal rod heated to 600 degrees C. The study was performed using 532-, 633-, 670-, 810-, and 980-nm diode lasers. Incident doses of 5, 10, 20, and 30 J/cm(2) and a treatment schedule of three times per week were used in the experiments. The burned areas on all rats were measured and plotted on a chart, and the slope values (mm(2)/d) and the percentages of burn healing were compared. RESULTS: The percentage of burn healing on diabetic rats after LLLT was 78.37% for the visible lasers and 50.68% for the invisible lasers. There was a significant difference (p < 0.005) between visible lasers and invisible lasers in the percentage of burn healing on diabetic rats after laser therapy. CONCLUSION: LLLT at the appropriate treatment parameters can accelerate burn healing on diabetic rats using both visible and invisible lasers. The effects of visible lasers were better than those of invisible lasers in accelerating burn healing on diabetic rats in this study.
with control burns.
J Rehabil Res Dev. 2009;46(4):543-54.
Low-level laser therapy with pulsed infrared laser accelerates third-degree burn healing process in rats.
Ezzati A, Bayat M, Taheri S, Mohsenifar Z.
Shahid Beheshti University, MC, Tehran, Iran.
This study investigated the influence of pulsed low-level laser therapy (LLLT) on the healing of a third-degree burn in a rat model. Two third-degree burns (distal and proximal) were made in the skin of 74 rats. Rats were divided into four groups. In group 1, the distal burn received LLLT with laser switched off; in groups 2 and 3, distal burns were treated with a 3,000 Hz-pulsed infrared diode laser with 2.3 and 11.7 J/cm(2) energy densities, respectively. In group 4, the distal burns were treated topically with 0.2% nitrofurazone. The proximal burn of all groups was considered a control burn. We assessed the response to treatment both microbiologically and macroscopically. The chi-square test showed that the incidence of Staphylococcus epidermidis, Lactobacillus, and diphtheria decreased significantly in laser-treated groups compared with other groups. Independent sample t-test showed that LLLT with 11.7 J/cm(2) energy density significantly increased wound-closure rate at 3 and 4 weeks after burning compared with their relevant control burns (p = 0.018 and p = 0.01, respectively). Pulsed LLLT with 11.7 J/cm(2)/890 nm of a third-degree burn in a rat model significantly increased wound-closure rate compared with control burns.
Photomed Laser Surg. 2008 Feb;26(1):47-54.
Effectiveness of laser photobiomodulation at 660 or 780 nanometers on the repair of third-degree burns in diabetic rats.
Meireles GC, Santos JN, Chagas PO, Moura AP, Pinheiro AL.
Laser Center, School of Dentistry, Department of Propedeutics and Integrated Clinics, Universidade Federal da Bahia, Salvador, Brazil.
OBJECTIVE: The aim of this investigation was to compare by light microscopy the effects of laser photobiomodulation (LPBM) at lambda = 660 nm and lambda = 780 nm on third-degree burns in diabetic Wistar rats. BACKGROUND DATA: Burns are severe injuries that result in fluid loss, tissue destruction, infection, and shock, that may result in death. Diabetes is a disease that reduces the body’s ability to heal properly. LPBM has been suggested as an effective method of improving wound healing. MATERIALS AND METHODS: A third-degree burn measuring 1.5 x 1.5 cm was created in the dorsum of each of 55 animals, and they were divided into three groups that were or were not treated with LPBM (lambda = 660 nm or lambda = 780 nm, 35 mW, varphi = 2 mm, 20 J/cm(2)). The treatments were started immediately post-burn at four points within the burned area (5 J/cm(2)) and were repeated at 24-hour intervals over 21 d. The animals were humanely killed after 3, 5, 7, 14, and 21 d by an overdose of intraperitoneal general anesthetic. The specimens were routinely cut and stained and analyzed by light microscopy. RESULTS: We found that healing in the animals receiving 660-nm laser energy was more apparent at early stages, with positive effects on inflammation, the amount and quality of granulation tissue, fibroblast proliferation, and on collagen deposition and organization. Epithelialization and local microcirculation were also positively affected by the treatment. CONCLUSION: The use of 780-nm laser energy was not as effective as 660-nm energy, but it had positive effects at early stages on the onset and development of inflammation. At the end of the experimental period the primary effect seen was on the amount and quality of the granulation tissue. The 660-nm laser at 20 J/cm(2), when used on a daily basis, was more effective than the 780-nm laser for improving the healing of third-degree burns in the diabetic rats beginning at the early stages post-burn.
Photomed Laser Surg. 2008 Feb;26(1):1-5.
Effect of low-level laser therapy on mast cells in second-degree burns in rats.
Vasheghani MM, Bayat M, Rezaei F, Bayat A, Karimipour M.
Paramedical Faculty, Shaheed Beheshti University, M.C., Tehran, Iran.
OBJECTIVE: This study sought to investigate whether low-level laser therapy (LLLT) with a helium-neon (He-Ne) laser would affect mast cell number and degranulation in second-degree burns in rats. Background Data: LLLT has been recently applied to stimulate the wound healing process.
MATERIALS AND METHODS: Sixty-five rats were randomly allocated to one of five groups. A deep second-degree burn was inflicted on all rats except those in the control group. In the sham-exposed group burns remained untreated. In the two laser-treated groups, the burns were irradiated every day by LLLT, with energy densities of 1.2 and 2.4 J/cm(2). In the fifth group the burns were treated topically with 0.2% nitrofurazone cream every day. The unburned skin of the rats in the control group were used for baseline study. The effects on mast cell number and degranulation were assessed by counting the number of intact and degranulated mast cells in sections fixed in formalin and stained with toluidine blue.
RESULTS: On the seventh and 16th days post-burn, the type 1 mast cell count in the 2.4-J/cm(2) laser-treated group was significantly higher than that of the control group. On the 30th day, the total numbers of mast cells in the laser-treated groups were lower than those in the control and sham-exposed groups.
CONCLUSION: LLLT of deep second-degree cutaneous burns in rats significantly increased the number of intact mast cells during the inflammatory and proliferative phases of healing, and decreased the total number of mast cells during the remodeling phase.
J Photochem Photobiol B. 2006 May 1;83(2):87-93. Epub 2006 Feb 7.
Effect of low-level helium neon laser therapy on the healing of third-degree burns in rats.
Bayat M, Vasheghani MM, Razavi N.
Cell and Molecular Biology Research Center, Department of Anatomy, School of Medicine, Shaheed Beheshti University of Medical Sciences, P.O. Box 19395/4719, Tehran, Evin 1985717443, Iran. firstname.lastname@example.org
This paper presents the results of a study on the effects of low-level helium-neon laser therapy (LL He-Ne LT) on the healing of burns. Seventy-eight adult male rats, having been subjected to third-degree burns, were randomly divided into four groups: two laser treated groups (n=20, each), one control group (n=19) and one nitrofurazone treated group (n=19). In the two laser treated groups, the burns were treated on a daily basis with LL He-Ne LT with an energy density of 1.2 and 2.4 J/cm(2), respectively. The response to treatment was assessed histologically at 7, 16 and 30 days after burning, and microbiologically at day 15. Analysis of variance showed that the mean of blood vessel sections in the 1.2J/cm(2) laser group was significantly higher than those in the other groups and the mean of the depth of new epidermis in the 2.4 J/cm(2) laser group on day 16 was significantly lower than in the nitrofurazone treated group (P=0.025, P=0.047, respectively). When Staphylococcus aureus and Pseudomonas aeruginosa grew in more than 50% of samples obtained from control group, there were no S. aureus and P. aeruginosa in the samples of 2.4 J/cm(2) laser group. It is concluded that LL He-Ne LT induced the destruction of S. aureus and P. aeruginosa in third-degree burns of rats, yet at the same time our histological findings showed that LL He-Ne LT caused a significant increase in the mean of blood vessel sections on day 7 after third degree burns and a decrease in the mean of the depth of new epidermis on day 16 after the same burns in rats.
|J Photochem Photobiol B. 2005 Feb 1;78(2):171-7.|
Effect of low-level laser therapy on the healing of second-degree burns in rats: a histological and microbiological study.
Bayat M, Vasheghani MM, Razavi N, Taheri S, Rakhshan M.
Anatomy Department, Medical Faculty, Cell and Molecular Biology Research Center, Shaheed Beheshti University of Medical Sciences, P.O. Box 19395/4719, Tehran, Iran. email@example.com
This paper presents the results of a study on the effects of two different doses of low-level laser therapy on healing of deep second-degree burns. Sixty rats were randomly allocated to one of four groups. A deep second-degree burn was inflicted in each rat. In the control group burns remained untreated; in two laser treated groups the burns were irradiated daily with low-level helium-neon laser with energy densities of 1.2 and 2.4 J/cm2, respectively. In the fourth group the burns were treated topically with 0.2% nitrofurazone cream every day. The response to treatments was assessed histologically at 7, 16 and 30 days after burning, and microbiologically at Day 15. The number of macrophages at day 16, and the depth of new epidermis at day 30, was significantly less in the laser treated groups in comparison with control and nitrofurazone treated groups (P=0.000). Staphylococcus epidermidis was found in the 70% of rat wounds in the laser treated groups in comparison with 100% of rats in the control group. S. aureus was found in the 40% rat wounds in the nitrofurazone treated group, but there was not found in the wounds of laser treated, and control groups. It is concluded that low-level laser therapy of deep second-degree burn caused significant decrease in the number of macrophage and depth of new epidermis. In addition, it decreased incidence of S. epidermidis and S. aureus.
Photomed Laser Surg. 2005 Jun;23(3):245-50.
Burn healing with a diode laser: 670 nm at different doses as compared to a placebo group.
Al-Watban FA, Delgado GD.
Laser Medicine Section, Biological and Medical Research, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia. firstname.lastname@example.org
OBJECTIVE: A study on burn healing in rats was initiated using a diode laser at varied doses for determination of optimum dosimetry and treatment schedule. MATERIALS AND METHODS: A number of male Sprague-Dawley rats were randomly assigned to several groups. Anesthesia (a mixture of ketamine HCl and Xylocaine) was administered intraperitoneally. Burn on both flanks was created using a preheated metal probe and measured daily using a caliper. The right side of the treated rats was irradiated five times and three times per week. Slopes from the actual burn areas were obtained and compared against the control with the healing rate calculated and expressed in percent. RESULTS: In reference to the control group, no significant difference in healing was observed. In comparing both treatment schedules, there was likewise no significant difference at any day in both age-groups. Notably in younger rats, accelerated healing was observed with the highest rate in the lower range of doses (1 and 5 J/cm2), 12.4% and 11.6%, respectively. CONCLUSION: This experiment affirms that the beneficial effect on burn healing in rats is indeed affected by an interplay of several factors.
|J Clin Laser Med Surg. 2004 Feb;22(1):59-66.|
Effect of low-intensity polarized visible laser radiation on skin burns: a light microscopy study.
Ribeiro MS, Da Silva Dde F, De Araujo CE, De Oliveira SF, Pelegrini CM, Zorn TM, Zezell DM.
Center for Lasers and Applications, IPEN-CNEN/SP, Cidade Universitaria, Sao Paulo, Brazil. email@example.com
OBJECTIVE: This study was carried out to investigate the influence of low-intensity polarized visible laser radiation on the acceleration of skin wound healing. Background Data: Low-level laser therapy (LLLT) at adequate wavelength, intensity, and dose can accelerate tissue repair. However, there is still unclear information about light characteristics, such as coherence and polarization. Some studies indicate that linearly polarized light can survive through long propagation distance in biological tissue. MATERIALS AND METHODS: Three burns about 6 mm in diameter were created on the back of rats with liquid N(2). Lesion “L(//)” was irradiated by He-Ne laser (lambda = 632.8 nm), D= 1.0 J/cm(2), with linear polarization parallel to the spinal column of the rat. Lesion “L(inverted v)” was irradiated using the same laser and dose, but the light polarization was aligned perpendicularly to the relative orientation. Lesion “C” was not irradiated in order to be considered as control. The animals were sacrificed at day 3-17 after lesion creation. Samples were collected and prepared for histological analysis. RESULTS: Histological analysis showed that the healing of irradiated wounds was faster than that of non-irradiated wounds. Moreover, it was observed that skin wound repair is dependent on polarization orientation with respect to a referential axis as the animal’s spinal column. Consequently, “L(//)” was completely healed after 17 days, whereas “L (perpendicular) ” showed a moderate degree of healing after the same period. CONCLUSIONS: These results indicate that the relative direction of the laser polarization plays an important role in the wound healing process when highly coherent He-Ne laser is used.