低能激光照射对大鼠梗死后心肌组织的影响

目的 观察低能激光照射(LLLI)对大鼠梗死后心肌组织的影响.方法 冠状动脉结扎法制作雌性SD大鼠心肌梗死模型,3周后,经超声筛选合格心肌梗死大鼠随机分为两组:(1)低能激光照射组(LLLI组);(2)对照组(Control组);另设假手术组(Sham组).LLLI组应用低能激光开胸单次照射后,以逆转录-聚合酶链反应(RT-PCR)法和Western blot法检测LLLI处理区内心肌组织中血管内皮生长因子(VEGF)的表达,照射后1h、1d、1周,分别测定LLLI处理区内心肌组织中超氧化物歧化酶(SOD)活性和丙二醛(MDA)含量.结果 与Control组VEGF mRNA和蛋白的表达(2.12 ±0.58、1.02±0.41)及Sham组VEGF mRNA和蛋白的表达(2.42±0.26、0.92±0.37)比较,LLLI组显著提高了照射区域梗死后心肌组织中VEGF mRNA和蛋白的表达(4.42±2.88、2.62±1.83,P ＜0.05);Sham组与Control组之间比较差异无统计学意义(P＞0.05).在预处理后1h和1d,与Control组比较,LLLI组梗死后心肌组织中SOD的活性[(0.84±0.43)、(0.92±0.34) U/mg)]均显著提高;而MDA的产量[(0.56±0.31)、(0.50 ±0.29) nmol/mg]显著降低(P＜0.05).在预处理后1周,LLLI组与Control组之间上述指标差异无统计学意义(P＞0.05).结论 LLLI处理显著上调梗死后心肌组织中VEGF的表达及SOD的活性,降低了MDA的含量,从而能够改善梗死后心肌微环境,促进梗死后心肌细胞的再生与修复.     

Action of low-level laser therapy on living fatty tissue of rats

Little is known about the action of laser rays on normal adipose cells. The present study attempts to observe the behavior of fatty cells submitted to laser therapy. Dorsal fat pads of normal adult rats were submitted to low-level laser irradiation applied locally through intact skin, with four different dose schedules (4, 8, 12, and 16 J/cm²), with a further group being sham-irradiated. Histology, morphometry, immunofluorescence, and electron microscopy were all used to analyze irradiated tissues. Changes were restricted to the brown fatty tissue, in which a tendency was shown for multivacuolar cells to be transformed into the unilocular type. The number of cells which exhibited enlargement and fusion of small vacuoles was greater in the 4- and 16-J/cm² groups (p<0.05). Increased vascular proliferation and congestion was another more evident finding in laser-treated animals compared to nontreated animals. Low-level laser rays cause brown adipose fat droplets to coalesce and fuse. Additionally, they stimulated proliferation and congestion of capillaries in the extracellular matrix.     

Effects of increased low-level diode laser irradiation time on extraction socket healing in rats

Lasers in Medical Science - In our previous studies, we confirmed that low-level laser therapy (LLLT) with a 980-nm gallium–aluminum–arsenide diode laser was beneficial for the healing...     

Transcranial low-level infrared laser irradiation ameliorates depression induced by reserpine in rats

Transcranial low-level infrared laser is a modality of therapy based on the principle of photons delivered in a non-invasive manner through the skull for the treatment of some neurological conditions such as psychological disorders, traumatic brain injuries, and neurodegenerative diseases among others. In the present study, effects of low-level infrared laser irradiation with different radiation powers (80, 200, and 400 mW, continuous wave) were investigated on normal animals subjected to forced swimming test (FST). Results indicated that there are changes in FST parameters in animals irradiated with laser; the lowest dose provoked a significant increase in animal activity (swimming and climbing) and a significant decrease in animal’s immobility, while the highest laser dose resulted in a complete inverse action by significantly increasing animal immobility and significantly decreasing animal activity with respect to control animals. The lowest dose (80 mW) of transcranial laser irradiation has then utilized on animals injected with a chronic dose of reserpine (0.2 mg/kg i.p. for 14 days) served as an animal model of depression. Laser irradiation has successfully ameliorated depression induced by reserpine as indicated by FST parameters and electrocorticography (ECoG) spectral analysis in irradiated animals. The findings of the present study emphasized the beneficial effects of low-level infrared laser irradiation on normal and healthy animals. Additionally, it indicated the potential antidepressant activity of the low dose of infrared laser irradiation.     

Effect of low-level laser therapy on bone repair: histological study in rats

BACKGROUND AND OBJECTIVES: Bone remodeling is characterized as a cyclic and lengthy process. It is currently accepted that not only this dynamics is triggered by a biological process, but also biochemical, electrical, and mechanical stimuli are key factors for the maintenance of bone tissue. The hypothesis that low-level laser therapy (LLLT) may favor bone repair has been suggested. The purpose of this study was to evaluate the bone repair in defects created in rat lower jaws after stimulation with infrared LLLT directly on the injured tissue. STUDY DESIGN/MATERIALS AND METHODS: Bone defects were prepared on the mandibles of 30 Holtzman rats allocated in two groups (n = 15), which were divided in three evaluation period (15, 45, and 60 days), with five animals each. control group-no treatment of the defect; laser group-single laser irradiation with a GaAlAs semiconductor diode laser device (lambda = 780 nm; P = 35 mW; t = 40 s; Theta = 1.0 mm; D = 178 J/cm(2); E = 1.4 J) directly on the defect area. The rats were sacrificed at the pre-established periods and the mandibles were removed and processed for staining with hematoxylin and eosin, Masson's Trichrome and picrosirius techniques. RESULTS: The histological results showed bone formation in both groups. However, the laser group exhibited an advanced tissue response compared to the control group, abbreviating the initial inflammatory reaction and promoting rapid new bone matrix formation at 15 and 45 days (P<0.05). On the other hand, there were no significant differences between the groups at 60 days. CONCLUSION: The use of infrared LLLT directly to the injured tissue showed a biostimulating effect on bone remodeling by stimulating the modulation of the initial inflammatory response and anticipating the resolution to normal conditions at the earlier periods. However, there were no differences between the groups at 60 days.     

Effects of near-infrared low-level laser irradiation on microcirculation

BACKGROUND AND OBJECTIVE: Recently, there has been an increase in the clinical application of low-level laser irradiation (LLLI) in various fields. The present study was conducted to explore the effects of LLLI on microcirculation. STUDY DESIGN/MATERIAL AND METHODS: We investigated the effects of LLLI on rat mesenteric microcirculation in vivo, and on cytosolic calcium concentration ([Ca2+]i) in rat vascular smooth muscle cells (VSMCs) in vitro. RESULTS: LLLI caused potent dilation in the laser-irradiated arteriole, which led to marked increases in the arteriolar blood flow. The changes were partly attenuated in the initial phase by the superfusion of 15 microM L-NAME, but they were not affected by local denervation. Furthermore, LLLI caused a power-dependent decrease in [Ca2+]i in VSMCs. CONCLUSION: The circulatory changes observed seemed to be mediated largely by LLLI-induced reduction of [Ca2+]i in VSMCs, in addition to the involvement of NO in the initial phase.     

Effect of low-level laser therapy on healing of tenotomized Achilles tendon in streptozotocin-induced diabetic rats

Diabetes mellitus (DM) is associated with musculoskeletal damage. Investigations have indicated that healing of the surgically tenotomized Achilles tendon was considerably augmented following low-level laser therapy (LLLT) in non-diabetic, healthy animals. The aim of the present study was to evaluate the effect of LLLT on the Achilles tendon healing in streptozotocin-induced diabetic (STZ-D) rats via a biomechanical evaluating method. Thirty-three rats were divided into non-diabetic (n?=?18) and diabetic (n?=?15) groups. DM was induced in the rats by injections of STZ. The right Achilles tendons of all rats were tenotomized 1 month after STZ injections. The two experimental groups (n?=?6 for each group) of non-diabetic rats were irradiated with a helium–neon (He–Ne) laser at 2.9 and 11.5 J/cm² for ten consecutive days. The two experimental groups of diabetic rats (n?=?5 for each group) were irradiated with a He–Ne laser at 2.9 and 4.3 J/cm² for ten consecutive days. The tendons were submitted to a tensiometric test. Significant improvements in the maximum stress (MS) values (Newton per square millimeter) were found following LLLT at 2.9 J/cm² in both the non-diabetic (p?=?0.031) and diabetic (p?=?0.019) experimental groups when compared with their control groups. LLLT at 2.9 J/cm² to the tenotomized Achilles tendons in the non-diabetic and diabetic rats significantly increased the strength and MS of repairing Achilles tendons in our study.     

In vitro effects of low-level laser irradiation at 660 nm on peripheral blood lymphocytes

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/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. RESULTS: 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. 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.     

The effects of vanadium treatment on bone in diabetic and non-diabetic rats

Vanadium-based drugs lower glucose by enhancing the effects of insulin. Oral vanadium drugs are being tested for the treatment of diabetes. Vanadium accumulates in bone, though it is not known if incorporated vanadium affects bone quality. Nine- to 12-month-old control and streptozotocin-induced diabetic female Wistar rats were given bis(ethylmaltolato)oxovanadium(IV) (BEOV), a vanadium-based anti-diabetic drug, in drinking water for 12 weeks. Non-diabetic rats received 0, 0.25 or 0.75 mg/ml BEOV. Groups of diabetic rats were either untreated or treated with 0.25-0.75 mg/ml BEOV as necessary to lower blood glucose in each rat. In diabetic rats, this resulted in a Controlled Glucose group, simulating relatively well-managed diabetes, and an Uncontrolled Glucose group, simulating poorly managed diabetes. Plasma insulin, glucose and triglyceride assays assessed the diabetic state. Bone mineral density (BMD), mechanical testing, mineral assessment and histomorphometry measured the effects of diabetes on bone and the effects of BEOV on non-diabetic and diabetic bone. Diabetes decreased plasma insulin and increased plasma glucose and triglycerides. In bone, diabetes decreased BMD, strength, mineralization, bone crystal length, and bone volume and connectivity. Treatment was effective in incorporating vanadium into bone. In all treated groups, BEOV increased osteoid volume. In non-diabetic bone, BEOV increased cortical bone toughness, mineralization and bone formation. In controlled glucose rats, BEOV lowered plasma glucose and improved BMD, mechanical strength, mineralization, bone crystal length and bone formation rate. In poorly controlled rats, BEOV treatment slightly lowered plasma glucose but did not improve bone properties. These results suggest that BEOV improves diabetes-related bone dysfunction primarily by improving the diabetic state. BEOV also appeared to increase bone formation. Our study found no negative effects of vanadium accumulation in bone in either diabetic or non-diabetic rats at the dose given.     

Comparative study of the effects of low-intensity pulsed ultrasound and low-level laser therapy on bone defects in tibias of rats

The aim of this study was to investigate and to compare the effects of low intensity ultra-sound (LIPUS) and low-level laser therapy (LLLT) during the process of bone healing by means of histopathological and morphometric analysis. The animals were randomly distributed into three groups of 30 animals each: the control group (bone defect without treatment); the laser-treated group: (bone defect treated with laser), and the LIPUS-treated (bone defect treated with ultrasound). Each group was further divided into three different subgroups (n = 10) and on days 7, 13, and 25 post-injury, rats were killed with an intra-peritoneal injection of general anesthetic. The rats were treated with a 30-mW/cm² low-intensity pulsed ultrasound and a 830-nm laser at 50 J/cm². The results showed intense new bone formation surrounded by highly vascularized connective tissue presenting a slight osteogenic activity, with primary bone deposition being observed in the group exposed to laser in the intermediary (13 days) and late stages of repair (25 days). This was confirmed by morphometric analysis in which significant statistical differences (p < 0.05) were noticed when compared to the control. No remarkable differences were noticed in the specimens treated with ultrasound with regard to the amount of newly formed bone in comparison to the control group. Taken together, our results indicate that laser therapy improves bone repair in rats as depicted by histopathological and morphometric analysis, mainly at the late stages of recovery. Moreover, it seems that this therapy was more effective than US to accelerate bone healing.     

Effects of the combination of low-level laser irradiation and recombinant human bone morphogenetic protein-2 in bone repair

Low-level laser irradiation (LLLI) and recombinant human bone morphogenetic protein type 2 (rhBMP-2) have been used to stimulate bone formation. LLLI stimulates proliferation of osteoblast precursor cells and cell differentiation and rhBMP-2 recruits osteoprogenitor cells to the bone healing area. This in vivo study evaluated the effects of LLLI and rhBMP-2 on the bone healing process in rats. Critical bone defects were created in the parietal bone in 42 animals, and the animals were divided into six treatment groups: (1) laser, (2) 7?μg of rhBMP-2, (3) laser and 7?μg of rhBMP-2, (4) 7?μg of rhBMP-2/monoolein gel, (5) laser and 7?μg rhBMP-2/monoolein gel, and (6) critical bone defect controls. A gallium-aluminum-arsenide diode laser was used (wavelength 780?nm, output power 60?mW, beam area 0.04?cm(2), irradiation time 80?s, energy density 120?J/cm(2), irradiance 1.5?W/cm(2)). After 15?days, the calvarial tissues were removed for histomorphometric analysis. Group 3 defects showed higher amounts of newly formed bone (37.89%) than the defects of all the other groups (P?相似文献   

Effects of low-level laser irradiation on human blood lymphocytes in vitro

Low-level laser irradiation (LLLI) has various effects on cultured human lymphocytes in vitro, but little is known about such effects in whole blood. This study investigated whether LLLI affected lymphocyte count in human whole blood in vitro. A total number of 130 blood samples were collected from apparently healthy adult patients through venipuncture into tubes containing EDTA. Each sample was divided into two equal aliquots to be used as a non-irradiated control sample and an irradiated sample. The irradiated aliquot was subjected to laser wavelengths of 405, 589, and 780 nm with different fluences of 36, 54, 72, and 90 J/cm², at a fixed irradiance of 30 mW/cm². A paired student t test was used to compare between non-irradiated and irradiated samples. The lymphocyte counts were measured using a computerized hematology analyzer and showed a significant (P?<?0.02) maximum increase (1.6%) at a fluence of 72 J/cm² when compared with non-irradiated samples. This increase in lymphocyte count upon irradiation was confirmed by flow cytometry. At a wavelength of 589 nm and fluence of 72 J/cm², irradiation of whole blood samples showed a significant increase in CD45 lymphocytes and natural killer (NK) (CD16, CD56) cells, but no significant changes in CD3 T lymphocytes, T-suppressor (CD3, CD8) cells, T-helper (CD3, CD4) cells, and CD19 B lymphocytes when compared with their non-irradiated counterparts. Our results clearly demonstrate that NK cell count is altered by irradiation, which ultimately affects the whole lymphocyte count significantly.     

The effect of low-level laser irradiation on dog spermatozoa motility is dependent on laser output power

Biological tissues respond to low-level laser irradiation and so do dog spermatozoa. Among the main parameters to be considered when a biological tissue is irradiated is the output power. We have studied the effects on sperm motility of 655 nm continuous wave diode laser irradiation at different output powers with 3.34 J (5.97 J/cm²). The second fraction of fresh dog sperm was divided into five groups: control, and four to be irradiated with an average output power of 6.8 mW, 15.4 mW, 33.1 mW and 49.7 mW, respectively. At 0 min and 45 min after irradiation, pictures were taken and a computer aided sperm analysis (CASA) performed to analyse different motility parameters. The results showed that different output powers affected dog semen motility parameters differently. The highest output power showed the most intense effects. Significant changes in the structure of the motile sperm subpopulation were linked to the different output powers used.     

Study on the selection of laser wavelengths in the intravascular low-level laser irradiation therapy

According to the absorption spectra of blood and hemoglobin, a photon-bond energy formula is established using physical methods and the effects on hemoglobin of low-level laser at different wavelengths are analyzed. The results show that lasers with the peak wavelengths of 200～240, 275, and 342 nm in the whole blood absorption spectra curve are easy to destroy protein molecules and then lead to hemoglobin lose biological activity. While lasers with wavelengths longer than 800 nm will reduce the oxygen carrying capacity of blood, only lasers with wavelengths between 630 and 670 nm have the best efficacy.