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Argon Laser (argon + laser)

Distribution by Scientific Domains

Medical Sciences	57%

Terms modified by Argon Laser

argon laser photocoagulation

Selected Abstracts

Near-infrared dyes for six-color immunophenotyping by laser scanning cytometry

CYTOMETRY, Issue 3 2002
Andreas O.H. Gerstner
Abstract Background To adequately analyze the complexity of the immune system and reduce the required sample volume for immunophenotyping in general, more measurable colors for the discrimination of leukocyte subsets are necessary. Immunophenotyping by the laser scanning cytometer (LSC), a slide-based cytometric technology, combines cell detection based on multiple colors with their subsequent visualization without the need for physical cell sorting. In the present study, the filter setting of the LSC was adapted for the measurement of the far-red emitting dye cyanine 7 (Cy7), thereby increasing the number of measurable commercially available fluorochromes. Methods The optical filters of the LSC were replaced,photomultiplier (PMT) 3/allophycocyanin (APC): 740-nm dichroic long pass, and 670-/55-nm bandpass; PMT 4/Cy7: 810-/90-nm bandpass. Peripheral blood leukocytes were stained directly by fluorochrome-labeled antibodies or by indirect staining. The tandem dyes of Cy7 (phycoerythrin [PE]-Cy7, APC-Cy7) and the fluorochromes fluorescein isothiocyanate (FITC), PE, PE-Cy5, and APC were tested alone and in different combinations. Results With the new filter combination and tandem fluorochromes, Cy7 was measurable at 488-nm (argon laser) or 633-nm (helium-neon laser) excitation. Resolution was in the range of FITC for PE-Cy7 but approximately 30% lower for APC-Cy7; spillover into the respective donor fluorochrome channel for both tandem dyes was prominent. A six-color panel for leukocyte subtyping was designed. Conclusions With this adaptation, it is possible to measure the tandem conjugates PE-Cy7 and APC-Cy7. This new setup opens the way for six-color immunophenotyping by LSC. Cytometry 48:115,123, 2002. © 2002 Wiley-Liss, Inc. [source]

Characteristics of microcystin production in the cell cycle of Microcystis viridis

ENVIRONMENTAL TOXICOLOGY, Issue 1 2004
Keishi Kameyama
Abstract The correlation between the content of three microcystins (types LR, RR and YR) and the cell cycle of an axenic strain of Microcystis viridis, NIES-102, was investigated under conditions of high (16 mg L,1) and low (1.0 mg L,1) nitrate (NO3 -N) concentrations. Each phase of the cell cycle was identified using a flow cytometer equipped with a 488-nm argon laser using SYTOX Green dye, which binds specifically to nucleic acids and can be exited by the wavelength (Ex/Em: 504/523 nm on DNA). Microcystin concentration showed a positive linear correlation with DNA concentration. The microcystin content of the cells changed remarkably as the cell cycle process proceeded, with maximum content in the G2/M phase and minimum content in the G0/G1 phase. Under a condition of high NO3 -N concentration, the ratio of the total content in the G0/G1 phase to that in the G2/M phase was about 6:1. In contrast, for the two batch cultures the total content was 1.3-fold greater in the G2/M phase. The compositions of the three microcystins also changed along with the cell cycle process, although there was little difference in composition that was related to NO3 -N concentration. Therefore, there were distinctive compositions specific to each phase of the cycle, and the cell cycle of the M. viridis strain was more strongly responsible for both the quantity and the types of microcystin production than was the effect of NO3 -N concentration. © 2004 Wiley Periodicals, Inc. Environ Toxicol 19: 20,25, 2004. [source]

QUARTZ-TUNGSTEN-HALOGEN AND LIGHT-EMITTING DIODE CURING LIGHTS

JOURNAL OF ESTHETIC AND RESTORATIVE DENTISTRY, Issue 3 2006
Kraig S. Vandewalle DDS
Curing lights are an integral part of the daily practice of restorative dentistry. Quartz-tungsten-halogen (QTH), plasma-arc (PAC), argon laser, and light-emitting diode (LED) curing lights are currently commercially available. The QTH curing light has a long, established history as a workhorse for composite resin polymerization in dental practices and remains the most common type of light in use today. Its relatively broad emission spectrum allows the QTH curing light to predictably initiate polymerization of all known photo-activated resin-based dental materials. However, the principal output from these lamps is infrared energy, with the generation of high heat. Filters are used to reduce the emitted heat energy and provide further restriction of visible light to correlate better with the narrower absorbance spectrum of photo-initiators. The relatively inefficient emission typically requires corded handpieces with noisy fans. PAC lights generate a high voltage pulse that creates hot plasma between two electrodes in a xenon-filled bulb. The irradiance of PAC lights is much higher than the typical QTH curing light, but PAC lights are more expensive and generate very high heat with an inefficient emission spectrum similar to that of QTH bulbs. Light emitted from an argon laser is very different from that emitted from the halogen or PAC lights. The photons produced are coherent and do not diverge; therefore, lasers concentrate more photons of specific frequency into a tiny area. With very little infrared output, unwanted heat is minimized. However, argon lasers are very expensive and inefficient due to a small curing tip. LED curing lights have been introduced to the market with the promise of more efficient polymerization, consistent output over time without degradation, and less heat emission in a quiet, compact, portable device. This review evaluates some of the published research on LED and QTH curing lights. [source]

Étude de l'influence de l'évaporation d'un bac d'eau sur les transferts dans un canal corrugué

THE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 2 2000
Seghir Maamir
Abstract Les auteurs présentent une étude numérique et expérimentale des transferts qui s'effectuent par convection forcée dans un canal comportant une protubérance sinusoîdale et par convection naturelle dans un bac d'eau. L'étude numérique a été effectuée pour des nombres de Reynolds compris entre 35 et 350, plusieurs densité de flux de chaleur et pour des amplitudes de la protubérance comprises entre 0.005 et 0.02 m. Les résultats montrent que la diffusion de la vapeur d'eau dans l'air modifie le profil des lignes de courant qui devient convexe au-dessus de la surface libre de l'eau. En outre, l'evaporation atténue la perturbation engendrée par la protubérance et augmente les transferts de chaleur dans le canal. La visualisation de l'ecoulement, réalisée à l'aide d'un générateur de fumée d'encens, d'un laser à argon et d'une caméra vidéo à mis en évidence la complexité de l'interaction entre le flux de vapeur engendré par l'évaporation de l'eau du bac, l'écoulement de l'air dans le canal et les déperditions de chaleur à travers les parois latérales. Les résultats théoriques et expéri-mentaux sont en bon accord qualitatif. The authors present a numerical and experimental study on heat and mass transfers by forced convection in a channel with a sinusoidal protuberance and by natural convection in a reservoir full of water. The numerical study has been carried out for Reynolds numbers in a range of 35 to 350, several densities of heat flux and protuberance amplitude range of 0.005 to 0.02 m. Results show that the vapour diffusion in the air modifies the stream function profiles which become convex over the free surface of the water. In addition, the evaporation reduces the perturbation caused by the protuberance and increases the heat transfer rate in the channel. The visualisation of the flow, using smoke, an argon laser and a videocamera, shows the complexity of the interaction between the flow of vapour caused by the evaporation, the flow in the channel and the heat losses across the lateral walls. Theoretical and experimental results are in good qualitative agreement. [source]

4413: Analysis of gene expression in acute ischemic neuroretinas : a genome-wide screen discriminating occlusion (BRVO) versus laser effects in rats

ACTA OPHTHALMOLOGICA, Issue 2010
C OROPESA
Purpose Identification of genes differentially regulated in rat neuroretinas submitted to an experimental acute branch retinal vein occlusion (BRVO), to a laser treatment, or to no treatment at all. Methods We have developed an in vivo experimental model of venous occlusion by photodynamic thrombosis in rat retinas. After anaesthesia, a sodium fluorescein solution was injected in rat tail 15 minutes before laser treatments. To induce ischemia in tested retina, venous sites adjacent to the optic nerve head were photocoagulated with an argon laser. In one group of tested animals, the retina was exposed to laser treatment at sites located between major vessels. As this treatment may have an effect upon choroidal blood flow, control eyes were not subjected to laser treatment. RNAs were isolated from the neuroretina 30 minutes post treatments, and processed for Affymetrix gene-chip analysis. Results Genome-wide screen enabled us to identify 308 and 348 genes which were up- or down-regulated, respectively, by BRVO and laser treatment only. When we compared the transcriptomes of retinas subjected to vessel occlusion or laser treatment to the control one, we found that the expression profiles of, respectively, 116 and 126 genes were specifically modified. The majority of the up- and down-regulated genes encode proteins involved in different aspects of early stress response, neuroprotection, inflammation and apoptosis. Conclusion Our microarray analysis revealed changes in gene expression bearing similarities to gene expression results from other ischemia models. Furthermore, it revealed that laser treatment may have an unreported impact on retina's metabolism. [source]

Intravitreal bevacizumab (Avastin®) for neovascular age-related macular degeneration in treatment-naive patients

ACTA OPHTHALMOLOGICA, Issue 7 2009
Karen Bjerg Pedersen
Abstract. Purpose:, To report the effects of intravitreal bevacizumab (Avastin®) in treatment-naive patients with exudative age-related macular degeneration (ARMD) assessed by visual acuity (VA), optical coherence tomography (OCT) and contrast sensitivity. Methods:, A prospective, uncontrolled, pilot study of 26 eyes of 26 patients, all previously treatment-naive to photodynamic therapy, argon laser or anti-vascular endothelial growth factor (VEGF), were treated with one or more intravitreal injections of 1.25 mg bevacizumab. Of the 26 patients, 15 (57.7%) had occult choroidal neovascularization (CNV), 6 (23.1%) had predominantly classic CNV and 5 (19.2%) had minimally classic CNV. Ophthalmic outcome measures included changes in standardized Early Treatment Diabetic Research Study (ETDRS) VA, contrast sensitivity and OCT. The patients were examined at baseline and 1 week, 6 weeks, 3 months and 6 months after the first injection. Re-treatment was given on an ,as needed' basis. Results:, Twenty-four eyes of 24 patients completed 6 months of follow-up. Two patients chose to discontinue the study. Mean ETDRS VA score improved from 55 letters at baseline to 60 letters at 1 week (P < 0.01) and to 61 letters at 6 weeks (P < 0.01). No significant improvement in VA from baseline was found after 3 and 6 months. Patients with pigment epithelial detachment (PED) had a significantly worse outcome in VA at 6 months. Contrast sensitivity improved from baseline to 3 or 6 months, but this improvement was not statistically significant. Mean macular thickness decreased significantly from baseline to all follow-up examinations (P < 0.01). Conclusion:, Mean ETDRS VA improved significantly after 1 and 6 weeks; thereafter, it remained stable throughout the study period. Macular thickness improved significantly at all time points. The results indicate that 1.25 mg intravitreal bevacizumab is associated with functional as well as morphological improvement among treatment-naive ARMD patients. [source]