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At least 127 records · Page 7Linked to original sources
PubMed2005

Helium-neon laser in viability of random skin flap in rats.

BACKGROUND AND OBJECTIVES: The purpose of this study was to determine the role of helium-neon (He-Ne) laser random skin flap viability in rats. STUDY DESIGN/MATERIALS AND METHODS: Experimentally controlled randomized study. Forty-eight Wistar-EPM rats were used, weighed, and divided into 4 groups with 12 rats each. The random skin flap was performed measuring 10 x 4 cm, with a plastic sheet interposed between the flap and the donor site. The Group 1 (control) underwent sham irradiation with He-Ne laser. The Group 2 was submitted to laser irradiation, using the punctual contact technique on the skin flap surface. The Group 3 was submitted to laser irradiation surrounding the skin flap, and the Group 4 was submitted to laser irradiation both on the skin flap surface and around it. The experimental groups were submitted to He-Ne laser irradiation with 3 J/cm(2) energy density immediately after the surgery and for the four subsequent days. The percentage of necrotic area of the four groups was calculated at the 7th post-operative day, through a paper-template method. RESULTS: Group 1 reached an average necrotic area of 48.86%; Group 2, 38.67%; Group 3, 35.34%; and Group 4, 22.61%. After the statistic analysis, results showed that all experimental groups reached statistically significant values when compared to the control group, and Group 4 was the best one, when compared to all groups of this study (P<0.001). CONCLUSION: The He-Ne laser irradiation was efficient to increase random skin flap viability in rats.

Animals↗
PubMed2006

The role of laser fluence in cell viability, proliferation, and membrane integrity of wounded human skin fibroblasts following helium-neon laser irradiation.

BACKGROUND: In medicine, lasers have been used predominantly for applications, which are broadly termed low level laser therapy (LLLT), phototherapy or photobiomodulation. This study aimed to establish cellular responses to Helium-Neon (632.8 nm) laser irradiation using different laser fluences (0.5, 2.5, 5, 10, and 16 J/cm(2)) with a single exposure on 2 consecutive days on normal and wounded human skin fibroblasts. MATERIALS AND METHODS: Changes in normal and wounded fibroblast cell morphology were evaluated by light microscopy. Changes following laser irradiation were evaluated by assessing the mitochondrial activity using adenosine triphosphate (ATP) luminescence, cell proliferation using neutral red and an alkaline phosphatase (ALP) activity assay, membrane integrity using lactate dehydrogenase (LDH), and percentage cytotoxicity and DNA damage using the Comet assay. RESULTS: Morphologically, wounded cells exposed to 5 J/cm(2) migrate rapidly across the wound margin indicating a stimulatory or positive influence of phototherapy. A dose of 5 J/cm(2) has a stimulatory influence on wounded fibroblasts with an increase in cell proliferation and cell viability without adversely increasing the amount of cellular and molecular damage. Higher doses (10 and 16 J/cm(2)) were characterized by a decrease in cell viability and cell proliferation with a significant amount of damage to the cell membrane and DNA. CONCLUSIONS: Results show that 5 J/cm(2) stimulates mitochondrial activity, which leads to normalization of cell function and ultimately stimulates cell proliferation and migration of wounded fibroblasts to accelerate wound closure. Laser irradiation can modify cellular processes in a dose or fluence (J/cm(2)) dependent manner.

Cell Proliferation↗
PubMed1995

Relative blood velocity measurement in individual microvessels using the self-mixing effect in a fiber-coupled helium-neon laser.

A system has been developed for the measurement of relative blood velocity in micro-vessels by using the self-mixing effect of a laser. A helium-neon laser was coupled to a single-mode optical fiber and the pulled fiber tip (approximately 30 microns diameter) was positioned on a single microvessel. The backscattered Doppler-shifted laser light from moving red blood cells enters the laser cavity and modulates the laser output by influencing internal laser parameters. The signal of the laser output intensity change was produced using a fiber-coupled photodiode and processed by a signal processor. This processor yields an output signal proportional to the first moment of the power spectral density, i.e., the mean frequency of the Doppler shift, corresponding to the blood flow velocity on an arbitrary instrument scale. Results of the in vitro experiment demonstrated that the current method can detect moving particles in fluid and moving red blood cells in a small plastic tube. Data from the in vivo study showed that this system is capable of measuring relative blood velocity in arterioles and venules and can easily follow the cardiac cycle up to 360 beats/min. Primary data suggest that, in addition to high sensitivity, good spatial and temporal resolution, and convenience of use, the self-mixing technique may have an even greater capacity for analysis of blood flow in microvessels than explored in this study, since information on the absolute velocity and velocity distribution of red blood cells is available in self-mixing signal. Further study on its hematocrit dependence and particle bias effect is needed.

Animals↗
PubMed1986

Measurements of n-p correlations in the reaction of relativistic neon with uranium.

We report a preliminary measurement of coincident neutron-proton pairs emitted at 45 degrees in the interaction of 400, 530, and 650 MeV/A neon beams incident on uranium. Charged particles were identified by time of flight and momentum, as determined in a magnetic spectrometer. Neutral particles were detected using a thick plastic scintillator, and their time of flight was measured between an entrance scintillator, triggered by a charged particle, and the neutron detector. The scatter plots and contour plots of neutron momentum vs. proton momentum appear to show a slight correlation ridge above an uncorrelated background. The projections of this plane on the n-p momentum difference axis are essentially flat, showing a one standard deviation enhancement for each of the three beams energies. At each beam energy, the calculated momentum correlation function for the neutron-proton pairs is enhanced near zero neutron-proton momentum difference by approximately one standard deviation over the expected value for no correlation. This enhancement is expected to occur as a consequence of the attractive final state interaction between the neutron and proton (i.e., virtual or "singlet" deuterons). The implications of these measurements are discussed.

Elementary Particles↗
PubMed1988

Proton-proton correlations at small relative momentum in neon-nucleus collisions at E/A=400 and 800 MeV.

Proton-proton small angle correlations have been measured in neon-nucleus collisions, using the 4 pi detector Diogene, at 400 and 800 MeV per nucleon incident energies. Values of the size of the emitting region are obtained by comparison with the Koonin formula, taking into account the biases of the apparatus. The dependence of the density on target mass and incident energy is also analysed.

Carbon↗
PubMed1992

Cytokine production after helium-neon laser irradiation in cultures of human peripheral blood mononuclear cells.

The effects of laser light on the immune system have not been extensively characterized. Low-power laser sources, such as the helium-neon (He-Ne) laser with a wavelength of 632.8 nm, have been found to produce photobiological effects with evidence of interference with immunological functions. We have investigated the effects of He-Ne laser irradiation on Ficoll-Hypaque-isolated human peripheral blood mononuclear cells (PBMC). Cultured cells were irradiated for various times at two selected intensities and then stimulated with different mitogens. The rate of incorporation of 3H-thymidine into the DNA of stimulated cells decreased with increasing energy density. The levels of interleukin-1 alpha (IL-1 alpha), interleukin-2 (IL-2), tumour necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) in supernatants of the cultures were determined (irradiated either before or after stimulation). When stimulating cells after irradiation, significantly increased levels of all cytokines were detected after 30 min of irradiation (18.9 J cm-2), whereas after 60 min of irradiation (37.8 J cm-2) cytokine levels were found to be significantly decreased.

Cell Division↗
PubMed2005

Effects of helium-neon laser on the mucopolysaccharide induction in experimental osteoarthritic cartilage.

OBJECTIVE: To investigate the effects of mucopolysaccharide induction after treatment by low power laser for experimental osteoarthritis (OA). METHODS: Seventy-two rats with three different degrees of papain induced OA over right knee joints were collected for helium-neon (He-Ne) laser treatment. The severity of induced arthritis was measured by 99mTc bone scan and classified into three groups (I-III) by their radioactivity ratios (right to left knee joints). The rats in each group were further divided into study subgroups (Is, IIs, and IIIs) and control subgroups (Ic, IIc, and IIIc) randomly. The arthritic knees in study subgroups received He-Ne laser treatment, and those in controls received sham laser treatment. The changes of arthritic severity after treatment and follow-up 2 months later were measured. The histopathological changes were evaluated through light microscope after disarticulation of sections (H.E. stain), and the changes of mucopolysaccharide density in cartilage matrix were measured by Optimas scanner analyzer after Alcian blue (AB) stain. The densities of mucopolysaccharide induced after treatment in arthritic cartilage were compared and correlated with their histopathological changes. RESULTS: The density of mucopolysaccharide rose at the initial stage of induced arthritis, and decreased progressively in later stages. The densities of mucopolysaccharide in treated rats increased upon complete laser treatment more than those of the controls, which is closely related with the improvement in histopathological findings, but conversely with the changes in arthritic severity. CONCLUSION: He-Ne laser treatment will enhance the biosynthesis of arthritic cartilage, and results in the improvement of arthritic histopathological changes.

Animals↗
PubMed2006

Low-energy helium-neon laser induces locomotion of the immature melanoblasts and promotes melanogenesis of the more differentiated melanoblasts: recapitulation of vitiligo repigmentation in vitro.

Helium-neon laser (He-Ne Laser, 632.8 nm) is a low-energy laser that has therapeutic efficacy on various clinical conditions. Our previous study has demonstrated efficacy of He-Ne laser on vitiligo, a disease characterized by skin depigmentation. To regain skin tone on vitiligo lesions, the process began by the migration of the immature melanoblasts (MBs) to the epidermis, which was followed by their functional development to produce melanin. In this study, we investigated the physiologic effects of He-Ne laser irradiation on two MB cell lines: the immature NCCmelb4 and the more differentiated NCCmelan5. The intricate interactions between MBs with their innate extracelluar matrix, fibronectin, were also addressed. Our results showed that He-Ne laser irradiation enhanced NCCmelb4 mobility via enhanced phosphorylated focal adhesion kinase expression and promoted melanogenesis in NCCmelan5. In addition, He-Ne laser decreased the affinity between NCCmelb4 and fibronectin, whereas the attachment of NCCmelan5 to fibronectin increased. The alpha5beta1 integrin expression on NCCmelb4 cells was enhanced by He-Ne laser. In conclusion, we have demonstrated that He-Ne laser induced different physiologic changes on MBs at different maturation stages and recapitulated the early events during vitiligo repigmentation process brought upon by He-Ne laser in vitro.

Animals↗
PubMed1987

Changes in mouse Leydig cell steroidogenesis following infrared and helium-neon laser irradiation.

The effects on mouse Leydig cell steroidogenesis of infrared (IR) laser rays, in the presence or absence of helium-neon (He-Ne) radiations, were investigated. Testosterone (T) production in response to luteinizing hormone (LH) by mouse Leydig cells exposed to IR (4.2 X 10(-3) J/cm2/min) plus He-Ne (8.0 X 10(-7) J/cm2/min) laser radiations was significantly higher than that by control Leydig cells. The Leydig cell responsiveness to LH (T delta %), as well as the secretion of cyclic AMP (cAMP) and androstenedione (A) in response to the highest dose of LH (0.5 mIU), were also significantly increased by the IR plus He-Ne irradiation. In contrast, the He-Ne irradiation (8.0 X 10(-7) J/cm2/min) in the absence of IR rays failed to affect T production by mouse Leydig cells. Similar results were obtained by adding to the He-Ne rays a low dose of IR radiation (3.4 X 10(-3) J/cm2/min), whereas higher doses of IR radiations (4.2 X 10(-3) and 5.1 X 10(-3) J/cm2/min) elicited a similar significant increase of T production by mouse interstitial cells.

Animals↗
PubMed2000

Specific helium-neon laser sensitivity of the purified cytochrome c oxidase.

PURPOSE: In order to gain some insight into the mechanism of interaction between Helium-Neon (He-Ne) laser light and mitochondrial cytochromes, the sensitivity of cytochrome electron transfer activity to He-Ne laser was tested. MATERIALS AND METHODS: Irradiation of solutions containing either purified cytochromes or dissolved rat liver mitochondria was carried out (wavelength 632.8 nm, fluence rate 10 mW cm(-2), fluence 2 J cm(-2)); the irradiation conditions were the ones able to affect cytochrome c oxidase (COX) activity in mitochondria (Pastore et al., 1994). RESULTS: Cytochrome c oxidation catalysed by COX was affected by He-Ne laser irradiation of the purified enzyme. This result was obtained from measurements of the pseudo-first-order kinetic constant and from determinations of the turnover number of the enzyme, performed at different cytochrome c/COX ratios. Consistently, the kinetic parameters of COX changed. On the contrary, no alteration in the rate of electron transfer catalysed by either cytochrome c or bc1 complex was found. CONCLUSIONS: This study shows that purified COX is a specific target of He-Ne laser light; therefore, COX may be considered to be a mitochondrial photo-acceptor.

Animals↗
PubMed1996

Stimulation of ATP synthesis via oxidative phosphorylation in wheat mitochondria irradiated with helium-neon laser.

In order to ascertain whether oxidative phosphorylation in plant mitochondria is sensitive to light, coupled durum wheat (Triticum durum Desf.) mitochondria were irradiated with a low power continuous wave Helium-Neon laser (fluence: 2 Joules/cm2), with measurements made of certain processes related to ATP production. As a result of irradiation, an increase in the rate of ATP synthesis was found, as continuously monitored via luciferine/luciferase, moreover the mitochondrial ATP and ADP endogenous contents were found to increase and decrease, respectively with a 1:1 stoichiometry, as revealed by HPLC measurements. Consistently, an increase in mitochondrial rate of delta psi generation was found as measured by using the fluorescent probe safranine. Thus, this paper gives a first evidence of a novel property of plant mitochondria: the direct light sensitivity of ATP synthesis via oxidative phosphorylation.

Adenosine Triphosphate↗
PubMed1996

In vitro synthesis of prostaglandin E2 by synovial tissue after helium-neon laser radiation in rheumatoid arthritis.

This paper reports the effect of helium-neon laser radiation (power of 5 mW and 632.8 nm wave length) on the synthesis of PGE2 in vitro in synovial tissue of biopsy samples of knee joints in patients with chronic rheumatoid arthritis stages II or III. Twelve patients were studied. Each patient received 15 applications of He-Ne laser. Eleven points for He-Ne laser applications were selected in one of the affected knees. The energy density used was 8 J/cm2 per application point. The He-Ne laser therapy reduced the synthesis of PGE2. The analysis of the data revealed a statistically significant difference between the levels of the synthesis of PGE2 before treatment (17.69 +/- 2.65 ng mg-1 of dry tissue h-1) and after treatment (13.85 +/- 2.73 ng mg-1 of dry tissue h-1), with p < 0.01 comparing mean values. This was also accompanied by relief of pain (91.6%), and a favorable subjective report from the patient. We conclude that PGE2 is a quantifiable parameter that could explain what causes pain relief in patients with rheumatoid arthritis that are treated with He-Ne laser.

Aged↗
PubMed1999

Complex hprt deletion events are recovered after exposure of human lymphoblastoid cells to high-LET carbon and neon ion beams.

Hypoxanthine phosphoribosyltransferase gene (hprt) mutations were induced in human TK-6 lymphoblastoid cells by irradiation at a linear energy transfer (LET) of 250 or 310 keV/micron for carbon and neon ions, respectively. At such a high level of LET, ions will lose most of their total energy and stop shortly after passing through the cell. The hprt mutations were analyzed by multiplex PCR, long-PCR and DNA sequencing of both genomic and cDNA. Over half of the C ion-induced hprt mutations (10 of 19) were point mutations, in contrast to 15% of the mutations induced by Ne ions (three of 20). The remaining 47 and 85% of the C and Ne ion-induced mutants, respectively, are deletion events. The latter events include three complex losses of multiple non-contiguous exon regions in both ion irradiation collections. We note that mutations involving the exon 6 region are frequent in the Ne ion collection: all three of the complex events retained the exon 6 region with flanking deletion of sequence and three other mutants involved deletion of this region. It may be concluded that these high-LET C and Ne ion irradiations produce different mutational spectra.

Carbon↗
PubMed1988

Effect of helium-neon laser irradiation on peripheral sensory nerve latency.

The purpose of this randomized, double-blind study was to determine the effect of a helium-neon (He-Ne) laser on latency of peripheral sensory nerve. Forty healthy subjects with no history of right upper extremity pathological conditions were assigned to either a Laser or a Placebo Group. Six 1-cm2 blocks along a 12-cm segment of the subjects' right superficial radial nerve received 20-second applications of either the He-Ne laser or a placebo. We assessed differences between pretest and posttest latencies with t tests for correlated and independent samples. The Laser Group showed a statistically significant increase in latency that corresponded to a decrease in sensory nerve conduction velocity. Short-duration He-Ne laser application significantly increased the distal latency of the superficial radial nerve. This finding provides information about the mechanism of the reported pain-relieving effect of the He-Ne laser.

Adult↗
PubMed1993

Technique for standardization of panoramic radiographs using helium-neon laser guided positioning.

A limitation of the use of panoramic radiography in implant dentistry has been variations in patient positioning, which can produce dissimilar radiographs and is a serious problem in longitudinal investigations. Previous techniques to standardize panoramic radiographs have been cumbersome and technique sensitive. Bilateral helium-neon lasers were mounted on two-axis micrometer translation stages and projected as cross-hairs on a phantom skull. The cross-point of each pattern was superimposed on a facial soft tissue landmark on either side of the skull. Laser coordinates were recorded and an initial radiograph was produced for each of three experimental groups. Two investigators repeated radiographs for each group six times using the original settings. The radiographs were digitized and the variance calculated and compared using a video digital analysis program. Repeat radiographs were compared to the originals by superimposing each pair and measuring the variance in radiographic markers. The variance ranged from 0.1 to 2.2 mm with the experimental groups and from 2.5 to 38.7 mm with the control group. Repeated measures analysis of variance showed no statistical significance (P > 0.125) among each of the experimental groups using the laser system and a significant difference (P < 0.001) when the control group is included in the analysis. Variance for experimental groups was not significant between the examiners (P > 0.45). A laser repositioning system may have application in implant dentistry by standardizing panoramic radiographs for comparisons in long-term investigations.

Analysis of Variance↗
PubMed1993

Sensitisation of cariogenic bacteria to killing by light from a helium-neon laser.

Suspensions of the cariogenic bacteria Streptococcus mutans, S. sobrinus, Lactobacillus casei and Actinomyces viscosus were exposed to light from a 7.3-mW helium-neon laser in the presence of toluidine blue O. A substantial killing rate (c. 10(6) cfu) of all four species was achieved with a dye concentration of 50 micrograms/ml and a light energy dose of 33.6 J/cm2. This was achieved in 60 s, an exposure time that is clinically acceptable. Exposure to laser light in the absence of the dye did not significantly affect the viability of any of the organisms. This approach may be useful in dentistry to sterilise a carious lesion prior to its repair.

Actinomyces viscosus↗
PubMed1990

Low-energy helium-neon laser irradiation increases the motility of cultured human keratinocytes.

Helium-neon (HeNe) laser irradiation is known to stimulate wound healing. We investigated whether the biostimulatory effects of HeNe irradiation result from enhancement of keratinocyte proliferation or motility. HeNe effects on keratinocyte motility were evaluated by irradiating a "wounded" culture with 0.8 J/cm2 3 times over a 20-h period. At 20 h post-irradiation, videocinemicroscopy and sequential quantitative measurements of the leading edge were taken over a 6-h period. There was a significant difference in migration of the leading edge in irradiated "wounds" compared to non-irradiated "wounded" controls (12.0 microns/h vs 4.0 microns/h, p less than 0.0001). To determine if the increase in migration observed in irradiated cultures resulted from a proliferative effect of HeNe irradiation, subconfluent human keratinocyte cultures were irradiated with single or multiple doses of different fluences of HeNe irradiation (0.4 to 7.2 J/cm2) and evaluated 72 h post-irradiation. Irradiated and non-irradiated keratinocyte cultures grown on a microporous membrane surface were co-cultured with irradiated and non-irradiated fibroblasts to determine if HeNe irradiation induced a paracrine effect on keratinocyte proliferation. No significant increase in keratinocyte proliferation was demonstrated in any of these treatments. The biostimulatory effects of HeNe irradiation may now be extended to include enhancement of keratinocyte motility in vitro; this may contribute to the efficacy of HeNe irradiation in wound healing.

Cell Division↗
PubMed1992

Comparison of infrared and helium-neon lasers in the measurement of blood flow in human skin by the laser-Doppler technique.

Histamine-induced changes in blood flow in normal human skin were assessed by laser-Doppler velocimetry using 2 lasers of different wavelengths: 780 nm infrared and 633 nm helium-neon. The visible flare response in skin was also measured by planimetry. Laser-Doppler velocimetry was shown to detect both the magnitude of the change in blood flow caused by histamine and also the extent of the changes in the skin. Both parameters were related to the dose of histamine, which ranged between 25 and 750 pmol/site. There was good correlation between the magnitude of the histamine-induced blood flow change and the extent of the response. The flare induced by histamine and measured by planimetry was similar in extent to the blood flow change recorded by laser-Doppler velocimetry. No difference in either the magnitude or the extent of blood flow changes in response to histamine, as measured by laser-Doppler velocimetry, were found when lasers of different wavelengths were used.

Adult↗