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PubMedDate not supplied

Neural control of motile activity of light-sensitive iridophores in the neon tetra.

Experiments with skin pieces revealed that the sympathetic nervous system controls the activity of the light-sensitive iridophores in the stripes of the neon tetra. The spectral peak reflected from the cells was shifted toward longer wavelengths as a result of a direct interaction between norepinephrine and alpha-adrenoceptors present on the cell membrane. Adenosine accelerated the recovery from the effects of the amine. Such regulation seems to operate when fish are in an excited state or under stress. Since alpha-melanophore-stimulating hormone (alpha-MSH), melanin-concentrating hormone (MCH) and melatonin caused the responses only at high concentrations, it is possible that these peptides and amine do not affect the properties of the light-reflecting cells in vivo.

Animals↗
PubMed1982

Changes in spectral reflexions from the iridophores of the neon tetra.

1. The iridescent stripe of the freshwater teleost, the neon tetra, changes from green in the daytime to violet-blue at night. 2. Spectral reflectance measurements were used to follow these colour changes. 3. Light causes a shift in reflectance to longer wavelengths in living fish and in isolated tissue from the lateral stripe. The change is reversed in darkness. 4. The spectral reflectance shifts to longer wavelengths when the fish is disturbed in darkness. No such colour changes were seen in fishes kept alive in 10(-4) M-reserpine. 5. Hypotonic Ringer solution causes a reflectance shift to longer wavelengths and hypertonic solution causes a shift to shorter wavelengths. 6. The iridescent reflexions from the lateral stripe which is continued across the iris originate from iridophores in the dermis. These iridophores contain regular stacks of broad, double-sided hexagonal plates that are about 10 nm thick. Each plate is contained within a pouch in the cytoplasm and is separated from its neighbour by approximately one quarter the wavelength of light. 7. A distinction is drawn between the physiologically active iridophores in the lateral stripe and iris that have broad hexagonal crystal plates which are very thin and the physiologically inactive iridophores that are also found in the iris, but in addition are found on the flanks below the lateral stripe, and on the head. These iridophores contain hexagonal crystals that are usually narrower than the active type, but are about 60-100 nm thick.

Animals↗
PubMed1987

Light-induced colour changes by the iridophores of the Neon tetra, Paracheirodon innesi.

The iridophores of the Neon tetra Paracheirodon innesi consist of alternating layers of guanine and cytoplasm. In the dark-adapted state the reflected light from constructive interference is in the ultraviolet or blue. When exposed to light the cytoplasm layers increase in thickness and as a result the reflections shift to longer wavelengths and the iridophores appear green. The iridophores are thought to contain a rhodopsin-like molecule and we suggest that the colour-change mechanism involves the light-induced opening of sodium channels in the plasma membrane, leading osmotically to an increase in thickness of the cytoplasm layers. Experimental support for this suggestion was obtained by the substitution of choline chloride for sodium chloride in the perfusing medium, which can be done without altering the osmotic strength of the perfusing medium. This procedure almost abolished the light response and makes it seem likely that sodium ions are necessary for the light response to take place.

Animals↗
PubMed2005

The watercolor illusion and neon color spreading: a unified analysis of new cases and neural mechanisms.

Coloration and figural properties of neon color spreading and the watercolor illusion are studied using phenomenal and psychophysical observations. Coloration properties of both effects can be reduced to a common limiting condition, a nearby color transition called the two-dot limiting case, which clarifies their perceptual similarities and dissimilarities. The results are explained by the FACADE neural model of biological vision. The model proposes how local properties of color transitions activate spatial competition among nearby perceptual boundaries, with boundaries of lower-contrast edges weakened by competition more than boundaries of higher-contrast edges. This asymmetry induces spreading of more color across these boundaries than conversely. The model also predicts how depth and figure-ground effects are generated in these illusions.

Adaptation, Ocular↗
PubMed2005

Explanation for neon color effect in achromatic line segments on chromatic inducers based on the multiple interpretation hypothesis.

In van Tuijl's neon configurations, an achromatic line segment on a blue inducer produces yellowish illusory color in the illusory area. This illusion has been explained based on the idea of the complementary color induced by the blue inducer. However, it is proposed here that this illusion can be also explained by introducing the assumption that the visual system unconsciously interprets an achromatic color as information that is constituted by transparent and nontransparent colors. If this explanation is correct, not only this illusion, but also the simultaneous color contrast illusion can be explained without using the idea of the complementary color induction.

Adult↗
PubMed1995

Effect of a helium-neon laser on cutaneous inflammation.

A Helium-Neon (He-Ne) laser with a wavelength of 632.8 nm is known to have photobiological effects and is widely used for reducing the pain of herpes zoster and accelerating wound healing, however the cellular mechanism and effect of the He-Ne laser are poorly understood. The present study was designed to examine the influence of He-Ne laser irradiation on irritant and allergic contact dermatitis of the mouse ear and on histamine release from rat peritoneal mast cells. Irradiation was applied with a He-Ne laser (12.2 J/cm2) at 1 h, 10 min, 5 min and 0 min before, and 5 min, 6 hs and 24 hs after a challenge of an irritated contact dermatitis (ICD) or allergic contact dermatitis (ACD) was made on the right ears of ICR-mice. Twenty-four hours after the challenge, the swelling of the ear was measured with a dial thickness gauge, and the anti-inflammatory effect of He-Ne laser irradiation was expressed as an ear thickness ratio (ETR). Although the laser did not decelerate the ETR from ICD, the allergic response was decelerated. Irradiation at 5 min after the challenge of contact dermatitis increased the thickness ratio. Next, the influence of the He-Ne laser on histamine release from Wistar-rat peritoneal mast cells was observed. The spontaneous histamine release was inhibited by laser irradiation, while substance P and compound 48/80-induced histamine release were not inhibited. From these results, it can be suggested that He-Ne laser irradiation has an anti-inflammatory effect on cutaneous inflammation.

Animals↗
PubMed1999

Bactericidal effect of 0.95-mW helium-neon and 5-mW indium-gallium-aluminum-phosphate laser irradiation at exposure times of 30, 60, and 120 seconds on photosensitized Staphylococcus aureus and Pseudomonas aeruginosa in vitro.

BACKGROUND AND PURPOSE: Studies have demonstrated a bactericidal effect of laser irradiation when lasers with power outputs of (6 mW are directed toward pathogenic or opportunistic bacteria previously treated with a photosensitizing agent. The purpose of this study was to determine the bactericidal capabilities of irradiation from lasers with power outputs of less than 6 mW on photosensitized microorganisms. METHODS: Two bacteria that commonly infect skin lesions, Staphylococcus aureus and Pseudomonas aeruginosa, were used. The 2 lasers used, the 0.95-mW helium -neon laser and the 5-mW indium-gallium-aluminum-phosphate laser, emit light at a wavelength close to the absorption maxima of the sensitizing agent chosen, toluidine blue O. This agent was used because of its proven effectiveness in sensitizing bacteria. For each bacterial strain, toluidine blue O was added to a 108 cells/mL solution until a 0.01% weight/volume ratio was obtained. These mixtures were spread on agar-coated petri dishes, which were then exposed to 1 of the 2 lasers for 30, 60, and 120 seconds. The cultures were then grown overnight and examined for one or more visible zones of inhibition. The areas surrounding the irradiated zone provided a control for the effects of toluidine blue O alone. To determine the effects of laser irradiation without prior toluidine blue O sensitization, separate plates were established using unsensitized bacteria. RESULTS: Although inconsistencies between plates were noted, both lasers produced at least one zone of inhibition in both bacterial species at all 3 time periods. The 5-mW laser, however, produced a greater number of these zones. CONCLUSION AND DISCUSSION: Laser-induced microbial killing of photosensitized organisms could have clinical applications in the treatment of infected skin lesions, pending in vivo studies.

Colony Count, Microbial↗
PubMed1999

Effect of helium-neon laser on wound healing.

To estimate the biostimulatory effects of low intensity laser radiation on healing of skin wounds, two linear skin wounds were produced on either side of dorsal midline in rats and immediately sutured. Wounds on the left side were irradiated daily with helium neon laser at 4 Joules/sq.cm for 5 min., while those on right side were not exposed and served as controls. The mean time required for complete closure in control group was 7 days while irradiated test wounds took only 5 days to heal (P < 0.01). The mean breaking strength, as measured by the ability of the wound to resist rupture against force, was found to be significantly increased in the test group. Early epithelization, increased fibroblastic reaction, leucocytic infiltration and neovascularization were seen in the laser irradiated wounds. The results establish the biostimulatory effects of low intensity laser radiation on healing of skin wounds.

Animals↗
PubMed1999

[Helium-neon laser radiation in the therapy of urinary bladder and ureteral tuberculosis].

The paper presents a comparative assessment of conventional therapy methods and the author's proposed treatment by using low-intensity helium-neon laser radiation in combination with endovesical submucous administration of tuberculostatics and glucocorticosteroids into the area of lesion in patients with tuberculosis of the bladder and intramural ureter.

Glucocorticoids↗
PubMed2001

"Neon needles" in a haystack: the advantages of passive surveillance for West Nile virus.

Passive surveillance is usually viewed as less efficient for case ascertainment than active surveillance. However, for diseases with nonhuman animal reservoirs, active surveillance can be like looking for a needle in a haystack and may be prohibitively expensive. Fortunately for surveillance of West Nile virus (WNV) in the northeast US, the dead crows have served as "neon needles in a haystack"--indicators of viral activity that call attention to themselves. In 2000, laboratory testing of dead birds, including all species, birds found singly, with signs of trauma, or no compatible pathology, provided the first confirmation of viral activity in most areas. The surveillance factor most closely associated with the number of human cases was the dead crow density. In 2001, dead crow densities will be used as an additional index for monitoring human risk and need for prevention and control activities. If there are few crows in an area, if their case-fatality rate is reduced, or if there is public complacency about reporting dead crow sightings, this passive surveillance indicator may not be helpful in identifying areas likely to have occasional human cases or an outbreak.

Animals↗
PubMed2003

[A case report. Unconscious patient with neon yellow skin was intoxicated with dipyridamole].

A 66-year old man called for an ambulance from his home because of acute chest pain. When the crew arrived he was unresponsive and hypotensive. Sublingual nitroglycerine was given and subsequently the patient collapsed into circulatory failure and respiratory arrest. He was intubated and transported to the nearest hospital. The severe hypotension was combated with fluids and norepinephrine. During the next few hours his skin gradually turned intensely yellow, as did the urine. Acute myocardial infarction also occurred and renal failure developed. The cause of the neon-yellow colour was a complete mystery until a police patrol sent to his apartment found several empty packages of dipyridamole (Persantin Depot) corresponding to 34 g, an overdose seven times higher than any previous case reported in the literature. This drug has a distinct yellowish colour. The patient's condition gradually improved and he could be extubated within a week. Haemodialysis was needed for two weeks because of acute tubular necrosis after the prolonged period of hypotension, but thereafter he recovered.

Diagnosis, Differential↗
PubMed2004

[Effect of low intensity helium-neon laser and decimeter electromagnetic irradiation on functional indices of immune cells in patients with rheumatoid arthritis].

Clinical, laboratory, and immunoassay of 58 patients with rheumatoid arthritis, first and second degree of activity was carried out. Low-energy helium-neon laser exposure and decimeter electromagnetic radiation (DMEM) of peripheral blood was given along with the use of non-steroidal antiinflammatory drugs and methotrexate. Peculiarities of this magnetic-laser effect on proliferation response and apoptosis of mononuclear leucocytes in vitro and in vivo have been revealed. It was also established that the application of DMEM-therapy brought patients with RA in shorter period of time to clinical improvement evaluated by ACR criteria.

Adolescent↗
PubMed2004

Low-power Helium-Neon laser irradiation enhances the expression of VEGF in murine myocardium.

BACKGROUND: Low-power helium-neon (He-Ne) lasers have been increasingly widely applied in the treatment of cardiovascular diseases, and its vasodilation effect has been proven. The aim of this study was to determine the effects of low-power He-Ne laser irradiation directed at the precardial region of Wistar rats on capillary permeability in the myocardium and the expression of myocardial vascular endothelial growth factor (VEGF). METHODS: Sixteen rats were divided randomly into control and irradiated groups (n = 8, each). A He-Ne laser (632.8 nm) was applied to the irradiated group with a dose of 60.5 J/cm(2). Ferritin was perfused into the left femoral vein and capillary permeability was examined under an electron microscope. VEGF expression in the myocardium was investigated by immunohistochemical methods, RT-PCR, and image analysis. RESULTS: The ultrastructures of the myocardial capillaries were examined. Compared to the control group, more high-density granules (ferritin), which were present within the capillary endothelium and the mitochondrions of myocardial cells in the internal layer of the myocardium, were observed in the irradiated group. VEGF staining of the myocardium was stronger in the irradiated group than that in the control group. The optic density of the irradiated group (0.246 +/- 0.015) was significantly higher than that of the control group (0.218 +/- 0.012, P < 0.05). Finally, the levels of RT-PCR products of VEGF165 mRNA were 2.79 times higher in irradiated rats than in the control rats. CONCLUSIONS: Our study demonstrates that He-Ne laser irradiation (in doses of 60.5 J/cm(2)) increases myocardial capillary permeability and the production of VEGF in myocardial microvessels and in myocardium. Our study provides experimental morphological evidence that myocardial microcirculation can be improved using He-Ne laser irradiation.

Animals↗
PubMedDate not supplied

[Use of helium-neon laser device LTM-01 in the treatment of patients with chronic suppurative otitis media].

The all-purpose small-sized portable helium-neon laser unit LTM-I has been tested in a clinic. The unit is constructed on the basis of a quantum generator of 0.5-1.0 mW with a wave length of 632.8 nm. The unit is provided with special appliances allowing emission to be brought to the external auditory passage and the tympanic cavity. The unit was used to treat 110 patients with chronic purulent middle otitis. Exposure lasted 10-12 min. The treatment course consisted of 7-12 sessions. The favourable effect was noted by the 6-7th day of treatment in 52 patients with chronic purulent mesotympanitis with a protracted torpid course. Improvement of the cytological picture, disappearance of the microbial flora, normalization of immunological indices made it possible to arrive at a conclusion on the existence of a certain adaptogenic mechanism of action of laser emission.

Adolescent↗
PubMed2006

Effect of low level helium-neon (He-Ne) laser therapy in the prevention & treatment of radiation induced mucositis in head & neck cancer patients.

BACKGROUND & OBJECTIVES: Oral mucositis is a common debilitating complication of radiotherapy occurring in about 60 per cent of cancer patients. Considerable buccal toxicity of radiotherapy or chemotherapy in cancer patients to become discouraged and can affect their quality of life. In addition, such toxicity can alter the treatment plan. At present, there is no clinically appropriate prophylaxis efficacious antidote for mucositis. The low level laser (LEL) appears to be a simple, non-traumatic technique for the prevention and treatment of radiation induced mucositis. Therefore the present study was carried out to find out the effect of low-level helium-neon (He-Ne) laser in the prevention and treatment of radiation induced mucositis in head and neck cancer patients. METHODS: The patients with carcinoma of oral cavity with stages II-IV a being uniformly treated with curative total tumour dose of 66 Gy in 33 fractions over 6 wk were selected for the study. The patients were divided based on computer generated randamosization into laser (study group) and control groups with 25 patients in each group. Both study and control groups were comparable in terms of site of the lesion, stage of the cancer and histology. The study group patients were treated with He-Ne laser (wavelength 632.8 nm and output of 10mW) and control group patients were given oral analgesics, local application of anaesthetics, 0.9 per cent saline and povidine wash during the course of radiotherapy. RESULTS: All patients tolerated the laser treatment without any adverse effect or reactions. The result showed a significant difference in pain and mucositis (P<0.001) between the two groups. At the end of radiotherapy (after 6 wk) mean pain sure and mucositis grade were significantly lower (P<0.001) in the study group compared to control. INTERPRETATION & CONCLUSION: The low-level He-Ne laser therapy during the radiotherapy treatment was found to be effective in preventing and treating the mucositis in head and neck cancer patients. Further studies need to be done on a larger sample to find the mechanism.

Female↗
PubMed1991

[The treatment of suppurative and atonic wounds with the CO2 laser and the helium-neon laser].

The doctrine on wounds is the most important and current one in general surgery and reflects the level and development of medicine. Each surgeon should be well acquainted with all processes and stages of wound healing, because treatment of a suppurative wound requires keen knowledge and art. The basic principle of the local treatment of a septic wound is the thorough knowledge on the objective criteria underlying the course of the wound process and on the etiopathogenetic therapy. Laser therapy of wounds accomplishes adequate necrotomy, acts aseptically on the wound surfaces, inhibits the wound microbial flora and stimulates the regeneration processes. The authors record their experience in CO2 laser and helium-neon treatment of 120 patients with suppurative, atonic and decubital wounds over the period 1984-1990.

Adult↗
PubMedDate not supplied

[Histochemistry of proteins and their functionally active groups in the skin of the neck and mucous membrane of the oral cavity of white rats in the zone exposed to a helium-neon laser].

The author made experiments on 49 white rats exposing their cervical skin ano oral cavity mucous membrane to the irradiation beam of a 40 mvt helium-neon laser (lambda 6328A) during 10-15 minutes. The reactive capacity of proteins was found to have intensified and the content of functionally active groups, especially SH. to have increased as well as well as the activity of the cytochromozydase. When the exposition to laser irradiation was raised to 30 minutes pronounced morphohistochemical lesions were noted in the cervical skin and oral cavity mucous membrane. The data received may be useful in clinical practice for the application of low-power laser irradiation of 6328A wave length for stimulation of metabolic processes.

Animals↗