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PubMed2006

Light-sensitive motile iridophores and visual pigments in the neon tetra, Paracheirodon innesi.

Although motile iridophores in the longitudinal stripes of neon tetra skin are under control of the sympathetic nervous system, they also respond to light directly and show circadian color changes. Using neon tetra skin, we found that the photoresponse of iridophores depends on light intensity, and that light near 500 nm is most effective. RT-PCR demonstrated the expression of mRNAs encoding rhodopsin and two kinds of cone opsins (Pi-green1 and Pi-green2) in neon tetra skin where the light-sensitive iridophores exist. These mRNAs are also expressed in the lateral eyes. The cone opsin genes, Pi-green1 and Pi-green2, show high similarity with the g101 and g103 genes of unique green cone opsins (belonging to the MWS/LWS group) of the blind Mexican cavefish. These results show that Pi-green1, Pi-green2, and/or rhodopsin may play important roles in the photoresponse of neon tetra iridophores, which are most sensitive to light near 500 nm.

Animals↗
PubMed1987

Qualitative study of chromosomal lesions induced by neutrons and neon ions in human lymphocytes at G0 phase.

Chromosomal lesions, mitotic index and cell cycle progression delay induced by neutron (protons 34 MeV on beryllium) and neon (250 MeV/i) particles are studied in human lymphocytes. The cell cycle progression is slightly decreased at a dose of 1 Gy. Mitotic indexes are significantly decreased after irradiation by the different particles, except neon in 52-h cultures. By comparison to chromosome damages caused by gamma-rays, previously published, it is found that the lesions observed here are frequently more complex: the number of breaks is higher per abnormal mitosis and higher per rearrangement on the average. This complexity is higher for neon ions than for neutron beams.

Cell Cycle↗
PubMed1993

Neon colour spreading with and without its figural prerequisites.

Neon colour spreading has been shown to disappear if certain figural conditions are not met. Evidence is presented which suggests that these conditions are only incidentally related to the neon spreading effect; in particular, that they can be violated as long as the structure remains compatible with the interpretation of a transparent surface. It is proposed that neon spreading and classical colour assimilation share the same basic mechanism, and that the peculiar perceptual attributes of the former derive from the perceptual scissioning of ordinary assimilation colour. This process is identical to that occurring with nonillusory colours in phenomenal transparency.

Attention↗
PubMed1981

Comparative effects of 60Co gamma-rays and neon and helium ions on cycle duration and division probability of EMT 6 cells. A time-lapse cinematography study.

Exponentially growing cultures of EMT 6 cells were irradiated in vitro with neon ions, helium ions or 60Co gamma-rays. Time-lapse cinematography allowed the determination, for individual cells, of cycle duration, success of the mitotic division and the age of the cell at the moment of irradiation. Irradiation induced a significant mitotic delay increasing proportionally with the delivered dose. Using mitotic delay as an endpoint, the r.b.e. for neon ions with respect to 60Co gamma-rays was 3.3 +/- 0.2 while for helium ions it was 1.2 +/- 0.1. Mitotic delay was greatest in those cells that had progressed furthest in their cycle at the time of irradiation. No significant mitotic delay was observed in the post-irradiation generation. Division probability was significantly reduced by irradiation both in the irradiated and in the post-irradiated generation. The reduction in division probability obtained with 3 Gy of neon ions was similar to that obtained after irradiation with 6 Gy of helium ions or 60Co gamma-rays.

Cell Cycle↗
PubMed1997

LET dependence of cell death and chromatin-break induction in normal human cells irradiated by neon-ion beams.

We investigated the LET dependence of cell death and chromatin-break induction in normal human embryo cells irradiated by accelerated neon-ion beams. Neon-ion beams were generated by the Riken Ring Cyclotron (RRC) at the Institute of Physical and Chemical Research, Japan. Chromatin breaks were measured by counting the number of chromatin fragments detected by the premature chromosome condensation (PCC) technique. The results indicated that cell death and the induction of remaining chromatin breaks showed a qualitatively similar LET dependence. The LET RBE curves for both cell death and the induction of remaining chromatin breaks had a broad peak in the LET range of 120-300 keV/microm and steeply downward trend up to 340 keV/microm. These results suggest that there is a good correlation between cell death and the induction of remaining chromatin breaks by neon-ion beams with different LET values.

Cell Death↗
PubMedDate not supplied

[Rationale for using helium-neon laser in medical rehabilitation of patients with atrophy].

High resolution measurements of helium-neon laser spectra have been conducted about 0.64 mm wavelength. The singlet oxygen photo-generation was demonstrated to be responsible for the bioeffects of this spectral interval. Helium-neon radiation with 0.633 mm wavelength was used for medical rehabilitation of 15 patients with muscular atrophy as a result of wearing immobilizing plaster arm-bends on lower extremity fractures. 50-day hypokinesia of a damaged extremity induced differences in functional indices between damaged and healthy extremities in the same patient. This difference was diminishing more rapidly after laser therapy than in the control group though all patients had adequate rehabilitative treatment. Due to the likelihood of hypokinesia- and weightlessness-induced atrophies, helium-neon laser may be recommended for atrophy prophylaxis and treatment in both cases.

Adolescent↗
PubMed1987

Morphological criteria for comparing effects of X-rays and neon ions on mouse small intestine.

Several techniques have been used to assess changes in different parts of mouse small intestine three days after a single dose of either 16.5 Gy X-rays or 11 Gy neon beam. The doses were chosen to be approximately equivalent in terms of their effect on the number of microcolonies present. In qualitative terms, villous damage was seen after both types of radiation exposure: collared crypts, similar to those seen in biopsies taken from patients suffering from coeliac disease, were conspicuous after neon irradiation. In semi quantitative terms the doses used, although estimated from previous work to give biologically equivalent damage, produced a greater drop in microcolony numbers after X-irradiation. This makes all the more important the fact that significantly greater changes were seen after neon irradiation-a greater drop was seen in the number of villous profiles and the number of goblet cells per villus. There was also greater breakdown in the integrity of the villous basement membrane. Different responses after the two types of irradiation are therefore seen in the cryptal and villous compartment. Progress is being made towards identifying and quantitating radiation induced changes in different populations of cells or tissues in the small intestine.

Animals↗
PubMed1986

[The Helium-neon laser effect on skin and oral mucosal tissue].

The biological effects of the helium-neon (He-Ne) laser on skin and oral mucosa were examined for the first time electron microscopically. Canine epidermis, gingiva and sublingual regions were subjected to treatment by the helium-neon laser with varying exposure times. The exposed tissues were excised immediately after radiation and studied with an electron microscope. Depending on the exposure times, ultrastructural alterations were observed such as cytoplasmic vesiculation and vacuolization, mitochondrial changes, dilation of the endoplasmic reticulum, the Golgi cisternae and other endomembranes of the keratinocytes. Furthermore, ultrastructural changes were seen in stromal cells, endothelial cells of the blood and lymphatic vessels, nerves, muscle cells and in the extracellular compartment of the lamina propria. The ultrastructural alterations of different cell and tissue structures following helium-neon laser radiation were compared with the effects induced by other types of lasers. The results are discussed in light of the stimulation of biological cell processes by low-energy lasers.

Animals↗
PubMed1994

DNA double-strand breaks induced by high-energy neon and iron ions in human fibroblasts. II. Probing individual notI fragments by hybridization.

The initial yields of DNA double-strand breaks induced by energetic heavy ions (425 MeV/u neon and 250, 400 and 600 MeV/u iron) in comparison to X rays were measured in normal human diploid fibroblast cells within three small areas of the genome, defined by NotI fragments of 3.2, 2.0 and 1.2 Mbp. The methodology involves NotI restriction endonuclease digestion of DNA from irradiated cells, followed by pulsed-field gel electrophoresis, Southern blotting and hybridization with probes recognizing single-copy sequences within the three NotI fragments. The gradual disappearance of the full-size NotI fragment with dose and the appearance of a smear of broken DNA molecules are quantified. Assuming Poisson statistics for the number of double-strand breaks induced per NotI fragment of known size, absolute yields of DNA double-strand breaks were calculated and determined to be linear with dose in all cases, with the neon ion (LET 32 keV/microns) producing 4.4 x 10(-3) breaks/Mbp/Gy and all three iron-ion beams (LETs from 190 to 350 keV/microns) producing 2.8 x 10(-3) breaks/Mbp/Gy, giving RBE values for production of double-strand breaks of 0.76 for neon and 0.48 for iron in comparison to our previously determined X-ray induction rate of 5.8 x 10(-3) breaks/Mbp/Gy. These RBE values are in good agreement with results of measurements over the whole genome as reported in the accompanying paper (B. Rydberg, M. Löbrich and P. Cooper, Radiat. Res. 139, 133-141, 1994). The distribution of broken DNA molecules was similar for the various radiations, supporting a random distribution of double-strand breaks induced by the heavy ions over Mbp distances; however, correlated breaks (clusters) over much smaller distances are not ruled out. Reconstitution of the 3.2 Mbp NotI fragment was studied during postirradiation incubation of the cells as a measure of rejoining of correct DNA ends. The proportion of breaks repaired decreased with increasing LET.

Cells, Cultured↗
PubMed1992

Endoscopic enhancement of the healing of high-risk colon anastomoses by low-power helium-neon laser. An experimental study.

Recent studies suggest that helium-neon (He-Ne) lasers at low energy can enhance wound healing in intestinal anastomoses. In this experimental study, we tested the strength and collagen concentration of high-risk anastomoses of the rat colon after endoscopic irradiation by helium-neon laser. Our results show that repeated helium-neon laser irradiation (1.9 J/cm2) increases the bursting strength of the anastomoses by almost 100% on the fourth postoperative day. This effect is not observed by increasing the radiation dose (6.4 J/cm2). Differences in collagen (hydroxyproline) concentration did not reach statistical significance.

Anastomosis, Surgical↗
PubMed1986

Demonstration of elevated type I and type III procollagen mRNA levels in cutaneous wounds treated with helium-neon laser. Proposed mechanism for enhanced wound healing.

To assess laser modulation of wound healing, full-thickness cutaneous wounds were produced in the backs of pigs, and subjected to treatment with helium-neon laser. For comparison, some wounds were treated with non-laser energy source (a tungsten light) or left untreated as controls. Type I and type III procollagen mRNA levels were determined in the wounds by molecular hybridization with cDNA probes. The results indicated that type I and type III mRNA levels were markedly increased at days 17 and 28 of the healing in wounds treated with He-Ne laser, when compared to control or tungsten light-treated wounds. The results suggest that helium-neon laser stimulates wound healing by enhancing procollagen gene expression. These observations may have relevance to previous clinical studies suggesting that helium-neon laser stimulates wound healing.

Animals↗
PubMed2002

Neon matrix infrared spectrum of WH(6): a distorted trigonal prism structure.

Reactions of laser-ablated W atoms and H(2) molecules during condensation in excess neon give the WH, WH(2), WH(3), WH(4), and WH(6) hydride products. WH(6) absorptions increase on annealing to allow diffusion and further reaction of H(2) and decrease on photolysis such that six infrared bands can be grouped and assigned to WH(6). Excellent agreement between four observed neon matrix and four DFT calculated W-H stretching modes (two a(1) and two e) and bending and deformation modes (a(1) and e) confirms the present neon matrix preparation of WH(6) and the previous theoretical predictions of a distorted trigonal prism structure which is far from octahedral.

Journal Article↗
PubMed1990

Neon colors illuminate reading units.

The effect of syllable-size reading units on neon color was investigated in 6 experiments. The stimuli consisted of 5- or 7-letter words or pseudowords with a syllable break either just before or just after the middle (target) letter. The target letter was overlaid with a plaid of red and green lines that gave it an ambiguous neon color. The letters preceding the target were overlaid with a monochromatic grid (red or green), and the letters following the target were overlaid with the other color. Ss were significantly more likely to judge the target as more similar to the color of other letters within its syllable than colors of letters outside that unit. The effect was shown not to be an artifact of guessing strategy or eye movements. Word structure determined by orthography and morphology affected neon colors, but no effect was found for purely phonological units.

Adult↗
PubMed2005

Dissociative ionization of neon clusters Ne(n), n=3 to 14: a realistic multisurface dynamical study.

The molecular dynamics with quantum transitions (MDQT) method is applied to study the fragmentation dynamics of neon clusters following vertical ionization of neutral clusters with 3 to 14 atoms. The motion of the neon atoms is treated classically, while transitions between the adiabatic electronic states of the ionic clusters are treated quantum mechanically. The potential energy surfaces are described by the diatomics-in-molecules model in a minimal basis set consisting of the effective 2p orbitals on each neon atom for the missing electron. The fragmentation mechanism is found to be rather explosive, with a large number of events where several atoms simultaneously dissociate. This is in contrast with evaporative atom by atom fragmentation. The dynamics are highly nonadiabatic, especially at shorter times and for the larger clusters. Initial excitation of the neutral clusters does not affect the fragmentation pattern. The influence of spin-orbit coupling is also examined and found to be small, except for the smaller size systems for which the proportion of the Ne+ fragment is increased up to 43%. From the methodological point of view, most of the usual momentum adjustment methods at hopping events are shown to induce nonconservation of the total nuclear angular momentum because of the nonzero electronic to rotation coupling in these systems. A new method for separating out this coupling and enforcing the conservation of the total nuclear momentum is proposed. It is applied here to the MDQT method of Tully but it is very general and can be applied to other surface hopping methods.

Journal Article↗
PubMed2006

Fragmentation dynamics of ionized neon clusters (Ne(n), n=3-14) embedded in helium nanodroplets.

We report a theoretical study of the nonadiabatic fragmentation dynamics of ionized neon clusters embedded in helium nanodroplets for cluster sizes up to n=14 atoms. The dynamics of the neon atoms is modeled using the molecular dynamics with quantum transitions method of Tully [J. Chem. Phys. 93, 1061 (1990)] with the nuclei treated classically and transitions between electronic states quantum mechanically. The potential-energy surfaces are derived from a diatomics-in-molecules model to which induced dipole-induced dipole interactions are added. The effect of the spin-orbit interaction is also discussed. The helium environment is modeled by a friction force acting on charged atoms whose speed exceeds the critical Landau velocity. The dependence of the fragment size distribution on the friction strength and on the initial nanodroplet size is investigated. By comparing with the available experimental data obtained for Ne3+ and Ne4+, a reasonable value for the friction coefficient, the only parameter of the model, is deduced. This value is then used to predict the effect of the helium environment on the dissociation dynamics of larger neon clusters, n=5-14. The results show stabilization of larger fragments than in the gas phase, but fragmentation is not completely caged. In addition, two types of dynamics are characterized for Ne4+: fast and explosive, therefore leaving no time for friction to cool down the process when dynamics starts on one of the highest electronic states, and slower, therefore leading to some stabilization by helium when it starts on one of the lowest electronic states.

Journal Article↗
PubMed1991

Illusory depth from moving subjective figures and neon colour spreading.

If a pattern of concentric circles, interrupted so as to produce the perception of a subjective bar extending from the centre to the periphery of the pattern, was slowly rotated in a plane perpendicular to the line of sight, observers reported seeing the bar slanted in depth and moving over complete and stationary concentric circles. When the interrupted concentric circles were completed by red segments--thereby giving rise to a neon colour-spreading effect--observers reported seeing a reddish bar, which sometimes appeared to be slanted in depth, moving behind the plane of the concentric circles. A combination of the two patterns was found to originate a compelling percept of a unitary bar slanted in depth: part of the bar (the subjective half) appeared to be located in front of its inducing elements, whereas the other part (the neon-like half) appeared to continue behind them. When translatory instead of rotary motion was used, the bars did not look slanted in depth: however, the neon bar appeared either behind or in front of the inducing lines, depending on the luminance contrast between the segments and the inducing lines themselves.

Attention↗
PubMed1998

Assimilation of achromatic color cannot explain the brightness effects in the achromatic neon effect.

If the mouths of the pacmen of a Kanizsa square are colored, for example red, then an illusory red transparent square is seen. In many visual theories such 'neon color spreading' is explained by assimilation of chromatic and achromatic color. In this paper the achromatic case was investigated. In a two-alternative forced-choice task thirty observers judged the brightness of achromatic neon figures. The results suggest that assimilation of achromatic color inside and/or outside of the illusory figures cannot explain the brightness effects seen in achromatic neon color spreading. Although these displays may produce assimilation, it appears that contrast (perhaps acting nonlocally) is a stronger influence on their perceived brightness.

Color Perception↗
PubMed2006

Solar wind neon from Genesis: implications for the lunar noble gas record.

Lunar soils have been thought to contain two solar noble gas components with distinct isotopic composition. One has been identified as implanted solar wind, the other as higher-energy solar particles. The latter was puzzling because its relative amounts were much too large compared with present-day fluxes, suggesting periodic, very high solar activity in the past. Here we show that the depth-dependent isotopic composition of neon in a metallic glass exposed on NASA's Genesis mission agrees with the expected depth profile for solar wind neon with uniform isotopic composition. Our results strongly indicate that no extra high-energy component is required and that the solar neon isotope composition of lunar samples can be explained as implantation-fractionated solar wind.

Journal Article↗