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At least 289 records · Page 16Linked to original sources
PubMed1997

A novel property of adenine nucleotides: sensitivity to helium-neon laser in mitochondrial reactions.

Consideration is made here of the ability of He-Ne laser light to affect both transport and enzymic reactions by acting on substrates. Adenine nucleotides irradiated with 3 Joules/cm2 fluence (10 mW/cm2 fluence rate) showed altered biochemical behaviour when used as substrates for certain mitochondrial reactions in isolated rat liver mitochondria: ADP/ATP antiport and ATP synthase, which allow for oxidative phosphorylation, and adenylate kinase reaction. In order to determine ATP synthase kinetics a specific method was developed which allows for calculation of ADP phosphorylation rate in intact mitochondria. While no change in ATP synthase kinetics was observed as a result of ADP irradiation, adenine nucleotides proved to be sensitive to He-Ne laser irradiation when their interaction with ADP/ATP carrier and adenylate kinase was considered.

Adenine Nucleotides↗
PubMed2004

In vitro effects of helium-neon laser irradiation on human blood: blood viscosity and deformability of erythrocytes.

OBJECTIVE: The purpose of this study was to investigate the in vitro effects of He-Ne laser irradiation on some rheological factors of human blood, such as blood viscosity, erythrocyte deformability, and sedimentation rate. BACKGROUND DATA: The intravascular irradiation of low power laser has been applied in pre-clinical and clinical to treat various pathological processes. However, the mechanism is not fully understood so far. Especially the interaction and related mechanism between the laser and blood are unclear. In this work, by measuring the change of the main rheological factors after laser irradiation, the interaction and mechanism were explored. METHODS: A30-mW He-Ne laser was used for irradiation with a 4-5-mm-diameter beam spot on blood samples, with a fluence rate of about 150 mW/cm.(2) The irradiation time was 60 min, so the total dose of irradiation was 540 J/cm.(2) The pathological samples of blood were obtained from patients (volunteers), and each sample was divided into two tubes for irradiation and control. The blood viscosity, erythrocyte deformability, and sedimentation rate were measured after laser irradiation and compared with un-irradiated control. The blood samples with poor erythrocyte deformability were prepared by adding Ca(2+) to the normal erythrocytes of a healthy person for investigating the laser effect on erythrocyte deformability further. RESULTS: Laser irradiation reduced the erythrocyte sedimentation rate of blood samples, which had a hyper-sedimentation rate originally. The blood viscosity of samples in hyper-values was lowered by laser irradiation in all shear rates measured (10-110 S(-1)), with a relative variation of approximately 10%. The deformability of erythrocytes from pathological samples and Ca(2+)-treated samples was improved after laser irradiation. CONCLUSIONS: The positive effects of laser irradiation on improving the rheological properties of blood were demonstrated in vitro.

Blood Sedimentation↗
PubMed2005

Biological effects of helium-neon laser irradiation on normal and wounded human skin fibroblasts.

OBJECTIVE: This study aimed to investigate a number of structural, cellular, and molecular responses to heliumneon (632.8 nm) laser irradiation following a single dose of 0.5, 2.5, 5, or 10 J/cm2 on normal and wounded human skin fibroblasts. BACKGROUND DATA: Low-level laser therapy (LLLT) is a form of phototherapy, involving the application of low-power monochromatic and coherent light to injuries and lesions to stimulate healing. 1 This therapy has been successfully used for pain attenuation and to induce wound healing in nonhealing defects. 2 METHODS: Changes in normal and wounded fibroblast cell morphology were evaluated by light microscopy. Cellular parameters evaluated cell proliferation, cell viability, and cytotoxicity while molecular parameters assessed the extent of DNA damage. RESULTS: The results clearly demonstrate that LLLT has an effect on normal and wounded(3) human skin fibroblasts. The parameters showed that doses of 0.5, 2.5, 5, and 10 J/cm2 were sufficient to produce measurable changes in fibroblast cells. CONCLUSION: A dose of 10 J/cm2 appeared to produce a significant amount of cellular and molecular damage, which could be an important consideration for other therapies, such as photodynamic therapy.

Cell Proliferation↗
PubMed2005

Helium-neon and nitrogen laser irradiation accelerates the phagocytic activity of human monocytes.

OBJECTIVE: Intracellular survival of mycobacteria within monocytes is a crucial stage in the pathogenesis of tuberculosis. The aim was to check intracellular survival of Mycobacterium fortuitum within the human monocytes exposed to He-Ne and nitrogen laser irradiation. BACKGROUND DATA: Tuberculosis remains one of the most important infectious diseases for developing countries. Low-level laser therapy (LLLT) has been tried to treat tubercular cavitory lung disease with encouraging results. The in vitro photobiological effect of low level laser radiation on the intracellular mycobacteria needs to be evaluated before we could go for large clinical trials. METHODS: The aliquots of human monocytes from peripheral blood of healthy volunteers and tuberculosis cases were exposed to He-Ne or nitrogen laser beam. The non-irradiated monocytes from the same source served as controls. The monocytes were then challenged with M. fortuitum, and surviving mycobacteria within monocytes were subjected to viable counts. RESULTS: Enhanced killing of mycobacterial cells was seen among monocytes exposed to He-Ne and nitrogen laser irradiation. CONCLUSIONS: He-Ne and nitrogen laser irradiation activates the monocytes to increase intracellular killing of mycobacteria.

Helium↗
PubMed1984

Neon-20 depth-dose relations in water.

The dose from heavy ion beams has been calculated using a one-dimensional transport theory and evaluated for 670 MeV/ amu 20Ne beams in water. The result is presented so as to be applicable to arbitrary ions for which the necessary interaction data are known. The present evaluation is based on the Silberberg - Tsao fragmentation parameters augmented with light fragment production from intranuclear cascades, recently calculated nuclear absorption cross sections, and evaluated stopping power data. Comparison with recent experimental data obtained at the Lawrence Berkeley Laboratory reveals the need for more accurate fragmentation data.

Ions↗
PubMed1996

Low-energy helium-neon laser irradiation stimulates interleukin-1 alpha and interleukin-8 release from cultured human keratinocytes.

Clinical observations have suggested that low-energy lasers might promote wound healing. Evidence suggests that He-Ne laser irradiation induces an increase in the rate of keratinocyte migration and proliferation as compared with nonirradiated controls in vitro. This study sought to determine whether He-Ne laser could induce cytokine production in cultured keratinocytes. The results revealed (i) a significant increase in interleukin-1 alpha and interleukin-8 production and their respective mRNA expression in He-Ne laser-treated groups as compared with nonirradiated controls, and (ii) under 1.5 joules/cm2 irradiation, this stimulating effect of He-Ne laser treatment is concentration-dependent. Because interleukin-1 alpha induces keratinocyte migration, this finding may partially explain the stimulatory effects on the motility of keratinocytes. As both interleukin-1 alpha and interleukin-8 provoke proliferation of keratinocytes, it is not unreasonable to propose that these two cytokines play a profound role in the enhancement of keratinocyte proliferation as a result of He-Ne laser irradiation. Our findings provide further evidence of enhanced wound healing at the cellular and molecular level as a result of the He-Ne laser.

Cells, Cultured↗
PubMed1992

Low-energy helium neon laser irradiation does not alter human keratinocyte differentiation.

There are reports that low-energy HeNe irradiation can enhance wound healing in vivo. We have previously demonstrated that HeNe irradiation increases the motility of human epidermally derived keratinocytes in vitro. Here we investigate whether HeNe irradiation alters normal keratinocyte differentiation, which is essential for the formation of a normal, functioning epidermis. Subconfluent keratinocyte cultures were irradiated three times within 24 h with either 0, 0.8, 3, or 7.2 J/cm2. After cultures reached post-confluence, parameters of growth and differentiation, such as cell number, cornified envelope (CE) formation, and transglutaminase activity were measured. No significant differences were found between the control (0 J) and irradiated cultures in these assays. We also examined the pattern of newly synthesized keratins in cultures irradiated with 7.2 J/cm2 three times within a 24-h period. Both control and irradiated cultures exhibited similar keratin patterns. These results provide evidence that HeNe irradiations of up to 7.2 J/cm2 have no direct deleterious effect on normal keratinocyte differentiation needed for the formation of a functional epidermis. Hence, it is anticipated that the clinical use of the HeNe laser irradiance that enhances keratinocyte migration in vitro (0.8 J/cm2) to promote wound healing in vivo will not alter the ultimate integrity or differentiated function of the epidermis that migrates to cover the wounded area.

Cell Differentiation↗
PubMed1987

Measurement in vitro of pulsatile arterial diameter using a helium-neon laser.

A noncontacting in vitro measurement of pulsatile arterial diameter using a scanning optical micrometer is described. The major component of this system is a He-Ne laser whose beam scans the pulsating artery to be measured. The laser micrometer was integrated into a pulsatile perfusion apparatus that imposed various hemodynamic conditions on excised canine vessels. The laser system reliably tracked the pulsating arterial diameter at a particular longitudinal site as well as at various increments in the presence of an experimentally created stenosis. The He-Ne laser measured the radial motion of canine arteries and various vascular substitutes anastomosed in an end-to-end fashion. From these novel measurements, calculations were made of arterial compliance and bending stress, two biomechanical parameters that are implicated as potential causes of anastomotic intimal hyperplasia and graft failure. Although this device is inherently limited to in vitro use, it is a potentially useful instrument for vascular physiology and biophysics.

Animals↗
PubMedDate not supplied

Effect of long-term aerobic exercise on helium-neon-laser-induced thrombogenesis in rat mesenteric arterioles and platelet aggregation.

We have previously investigated the antithrombotic effect of aerobic exercise in rat arterioles and venules under conditions of variable exercise load. In the present study, rats were subjected to constant exercise of 90% maximal oxygen uptake for 30 min, 5 times a week for 2, 4, 8 or 18 weeks. Thrombotic tendency was assessed by the He-Ne-laser-induced thrombus formation method. Platelet aggregation, platelet adhesion, whole blood clotting time, fibrinogen levels and blood cell count were also measured. The thrombotic tendency in arterioles decreased significantly after 18 weeks training, but not in venules. Thrombotic tendency increased slightly after 2 weeks training though the differences were not significant. A significant decrease in collagen-induced platelet aggregation was observed after 18 weeks training. The results demonstrated that long-term aerobic training decreased the thrombotic tendency in rat arterioles and that this was partly due to decreased platelet aggregability.

Animals↗
PubMedDate not supplied

Poor penetration of infra-red and helium neon low power laser light into the dermal tissue.

The skin transmittance for low power laser light was studied in vitro. The penetration of both He-Ne and infra-red lasers was observed for only a few millimeters. The most important absorption was observed at the depth level of 0.4 and 0.5 mm. These results suggested that the dermal vascular plexus barrier seemed to decrease the penetration at that level. This finding should mean that the laser therapy did not have really direct effects on the deep tissues. However, the effects can be mediated by many different pathways.

Absorption↗