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PubMed1992

Anaesthesia and the 'inert' gases with special reference to xenon.

Xenon has many of the properties of the ideal anaesthetic agent and has been proposed as a suitable replacement for nitrous oxide in routine clinical anaesthesia. Xenon, krypton and argon are chemically inert under most circumstances, yet all have anaesthetic properties. Xenon is of particular interest because it is the only 'inert' gas which is an anaesthetic under normobaric conditions. Because of this property, xenon has an important place in the history of the development of theories of anaesthetic action and of concepts such as MAC. Cost is likely to be a major impediment to the regular use of xenon.

Anesthesia, Inhalation↗

PubMedDate not supplied

Laser treatment of diffuse retinal pigment epitheliopathy.

The Authors report laser treatment of 18 eyes (14 patients) with a variant of central serous chorioretinopathy associated with widespread decompensation of the retinal pigment epithelium (RPE) in the macula, diffuse retinal pigment epitheliopathy (DRPE). All eighteen eyes with DRPE were treated with Krypton red laser photocoagulation in a grid pattern to leaking RPE in areas of neurosensory retinal detachment. All eyes showed anatomic improvement with resolution of the serous macular detachment and lipid exudation. The visual acuity was stabilized in 15 eyes (83%) at 6 months' follow-up, but only 3 eyes (17%) demonstrated improved visual acuity in the same time interval. At eighteen months, 2 of 15 eyes (13%) retained improved visual acuity, 11 eyes (74%) remained unchanged, and 2 eyes (13%) had visual loss. In this series of patients with DRPE, grid laser photocoagulation treatment was uniformly successful in producing an anatomic improvement in the exudative manifestations of the macula and in preventing or slowing progression of vision loss.

Aged↗

PubMed1979

Ultrafast laser scanner microscope.

Advances in monolayer deposition of cervical cells have removed one of the last serious obstacles to the design of high-resolution automated diagnostic assessment systems. In this article, we describe the design considerations for a system that is capable of acquiring, within 60 sec, a 0.5 micron digitized image of a 4 cm2 area on a standard glass slide. The most feasible approach is found to be a system using a rotating polygon to sweep the focused spot from a laser across a 2-mm scan line while the slide is uniformly translated perpendicular to the scan direction the use of laser sources (a helium-neon laser at 632 nm and a krypton ion laser at 568 and/or 476 nm) as compared to the incoherent light sources used in conventional microscope systems alleviates many of the optical design problems and provides the proper wavelengths needed for recognition of Papanicolaou stained cells. We also find that focus control of the scanning spot should be achievable using a technique involving a holographic grating. Other relevant considerations such as sample heating problems, multiphoton absorption by the sample, detector signal-to-noise ratios, laser amplitude noise control, and the digitization and buffering of the data stream are also discussed.

Computers↗

PubMed1979

Dual-laser flow cytometry of single mammalian cells.

An improved dual-laser flow cytometric system for quantitative analysis and sorting of mammalian cells has been developed using a low-power argon and high-power krypton laser as illumination sources, thus permitting the excitation of fluorescent dyes having absorption regions ranging from the ultraviolet to infrared. Cells stained in liquid suspension with fluorescent dyes enter a flow chamber where they intersect two spatially separated laser beams. Separate pairs of quartz beam-shaping optics focus each beam onto the cell stream. Electro-optical sensors measure fluorescence and light scatter signals from cells that are processed electronically and displayed as frequency distribution histograms. Cells also can be electronically separated and microscopically identified. The ease and versatility of operation designed into this system represent a marked technological improvement for dual-laser excited flow systems. Details of this instrument are described along with illustrative examples of cells stained with mithramycin and rhodamine and analyzed for DNA content, total protein, and nuclear and cytoplasmic diameter.

Animals↗

PubMed1992

UV lasers for flow cytometric analysis: HeCd versus argon laser excitation.

Applying flow cytometric single cell analysis, we compared the performance of UV excitation from argon ion and HeCd lasers using various UV-excitable fluorochromes of cell kinetic and cell physiological relevance. The AT-specific DNA fluorochromes DAPI, Hoechst 33258, and Hoechst 33342 showed no significant differences of G1-phase resolution and cell cycle distribution. With the HeCd laser, high-resolution cell kinetic analysis applying the novel BrdU/Hoechst-PI quenching technique showed superior resolution and an almost normalized G2M/G1 channel ratio of the first cell cycle. Indo-1 analysis for detection of intracellular free calcium gave similar results for both excitation sources, although the indo-1 ratio of activated cells was lower for HeCd excitation. Monochlorobimane as an indicator fluorochrome of glutathione content could not be excited sufficiently with the 325-nm line of the HeCd laser and exhibited poor resolution between positive and negative cells. However, the second glutathione-specific fluorochrome o-phtalaldehyde gave even better results with the HeCd laser. Our data indicate that air-cooled HeCd lasers are cheap and reliable UV-excitation sources for most UV-excitable fluorochromes, and might be an alternative to the expensive water-cooled argon and krypton laser.

Argon↗

PubMed1986

A new technique for xenon-133 ventilation imaging in the diagnosis of pulmonary embolism.

A new approach to ventilation imaging of the lung using 133Xe in patients with suspected pulmonary embolism is described. Three inhalation images are obtained in the postero-anterior, right posterior oblique and left posterior oblique projections, respectively, and each image contains 140-180 kcounts. The technique is quick and simple and needs neither an oxygen supply nor a spirometer. It combines the multiple views characteristic of krypton imaging with the ease of availability of xenon.

Humans↗

PubMed2002

Real-time color holographic interferometry.

A new optical technique based on real-time color holographic interferometry has been developed for analyzing unsteady aerodynamic wakes in fluid mechanics or for measuring displacements and deformations in solid mechanics. The technique's feasibility is demonstrated here. It uses three coherent wavelengths produced simultaneously by a cw laser (mixed argon and krypton). Holograms are recorded on single-layer panchromatic silver halide (Slavich PFG 03C) plates. Results show the optical setup can be adjusted to obtain a uniform background color. The interference fringe pattern visualized is large and colored and exhibits a single central white fringe, which makes the zero order of the interferogram easy to identify. An application in a subsonic wind tunnel is presented, in which the unsteady wake past a cylinder is recorded at high rate.

Journal Article↗

PubMed2005

Prism-based excitation wavelength selection for multicolor fluorescence coincidence measurements.

We have designed and constructed a prism setup for multiple-color confocal fluorescence experiments. The prism setup permits easy selection of any color or any combination of colors from a multicolor light source, such as a mixed-gas argon-krypton-ion laser. The selected colors emerging from the prism setup are, by design, optimally overlapped in the focus of a high-numerical-aperture objective, such as that commonly used in single-molecule fluorescence experiments. The various excitation powers can be easily adjusted in this setup. We will exemplify the potential of this setup in single-molecule fluorescence emission spectroscopy.

Journal Article↗

PubMed2005

Permanent refractive-index modification in germanium-doped optical fibers by use of red light.

We observed photoinduced birefringence in elliptical-core optical fibers by using a continuous-wave krypton-ion laser. We induced the birefringence by injecting 20 mW of 647-nm or 50 mW of 676-nm light into the fiber at 45 degrees to the slow axis. The rate of change of the refractive index was found to be proportional to the square of the average power. Polarization mode couplers written into the fibers have been stable for more than 2 years and can be erased by use of light polarized perpendicularly to the original writing beam.

Journal Article↗

PubMed1992

Impaired left lower lobe ventilation in patients with cardiomegaly. An isotope study of mechanisms.

Reduced left lower lobe ventilation (V) in patients with enlarged hearts has been commonly observed on routine isotope ventilation-perfusion lung scanning, and there is evidence to show that this reduction is dependent on posture. Clinically, it may have a role in posture-dependent dyspnea and postoperative left lower lobe changes in cardiomegaly. Previous studies have shown improvement in left lower lobe V in the prone compared with the supine position. In 11 patients showing this phenomenon in krypton 81m V scanning, a mean relative reduction in V of 53 percent occurred at the left base. No significant change in perfusion or in the signal from preinjected technetium 99m macroaggregated albumin was observed between the two positions. No significant change in ventilatory turnover (measured with intravenous xenon 133) was seen either, suggesting that no air trapping takes place. By combining the data from the intravenous 133Xe (which gives the ratio, V/lung volume) and continuously inhaled 81mKr (which reflects regional V), an index of relative volume between the two sides was derived and shown to be significantly reduced at the left base on moving from the prone to supine positions (a mean reduction of 40 percent; p less than 0.02 by Wilcoxon signed rank test). Thus, the mechanism of postural left lower lobe hypoventilation in cardiomegaly is predominantly a regional loss of alveolar volume.

Cardiomegaly↗

PubMed1986

Cardiopulmonary effects of a single oral dose of almitrine at rest and on exercise in patients with hypoxic chronic airflow obstruction.

Almitrine, a new triazine derivative, was studied in a double-blind, randomized, parallel study in 16 patients with hypoxic chronic airflow obstruction (eight almitrine and eight placebo). At rest, compared to placebo, a 3 mg/kg single dose of almitrine given orally significantly increased the partial pressure of oxygen (mean increase: +12.0 +/- SEM 2.1 mm Hg, p less than 0.001) and decreased the partial pressure of carbon dioxide (mean decrease: -6.0 +/- 0.7 mm Hg, p less than 0.001); this improvement in arterial blood gases persisted on exercise. The lack of significant change in ventilation and the decrease in the alveolar-arterial oxygen gradient (mean decrease -10.0 +/- 1.9 mm Hg; p less than 0.001) at rest suggests a change in the distribution of the ventilation-perfusion ratio in the lung; such a change was confirmed by a krypton 81m isotopic study. Pulmonary hemodynamic responses were studied at rest and on exercise; a significant but slight increase in mean pulmonary artery pressure at rest (+4.0 +/- 1.5 mm Hg, p less than 0.05) was found.

Administration, Oral↗

PubMed2006

An aerosolized fluorescent microsphere technique for evaluating particle deposition in the avian respiratory tract.

The objective of this study was to examine the feasibility of using aerosolized fluorescent microspheres to examine particle distribution in the respiratory tract of birds following aerosol exposure. Adult domestic pigeons (Columbia livia domestica; n = 5 birds per microsphere size) were exposed to aerosolized monodispersed populations of various sized carboxylate microspheres (0.5, 1.0, 2.0, 3.0, 6.0, and 10.0 microm) for 30 min. For aerosol-exposure purposes, the birds were anesthetized with injectable anesthetics, intubated, and placed on positive-pressure ventilation using a mechanical ventilator. Immediately following aerosol exposure, the birds were euthanatized, and carcasses were preserved via intravenous infusion of modified paraformaldehyde/gluteraldehyde fixative (pH = 7.2 and 340 mOsm). Initial evaluation of microsphere distribution in air sacs (cranial and caudal thoracic and abdominal) and at the level of the ostia was performed using a stereoscopic microscope with an epifluorescent module. More detailed examination of the distribution of microspheres within the respiratory tract was achieved using a confocal scanning laser microscope with a krypton argon laser and a scanning electron microscope. The results from this study revealed that positive-pressure ventilation resulted in distribution of smaller sized fluorescent microspheres (sizes 1.0, 2.0, and 3.0 microm) throughout the pigeon's respiratory tracts, and these microspheres were in highest concentration in the secondary bronchi and ostia for all of the examined air sacs. The larger sized beads (6.0 and 10.0) were confined to the upper airway (trachea and primary bronchi). The results from this study allow for a better understanding of particle deposition following positive-pressure ventilation and aerosol exposure in birds.

Aerosols↗

PubMed2001

Four-color flow cytometric detection of retrovirally expressed red, yellow, green, and cyan fluorescent proteins.

Flow cytometric procedures are described to detect a "humanized" version of a new red fluorescent protein (DsRed) from the coral Discosoma sp. in conjunction with various combinations of three Aequorea victoria green fluorescent protein (GFP) variants--EYFP, EGFP, and ECFP. In spite of overlapping emission spectra, the combination of DsRed with EYFP, EGFP, and ECFP generated fluorescence signals that could be electronically compensated in real time using dual-laser excitation at 458 and 568 nm. Resolution of fluorescence signals from DsRed, EYFP, and EGFP was also readily achieved by single-laser excitation at 488 nm. Since many flow cytometers are equipped with an argon-ion laser that can be tuned to 488 nm, the DsRed/EYFP/EGFP combination is expected to have broad utility for facile monitoring of gene transfer and expression in mammalian cells. The dual-laser technique is applicable for use on flow cytometers equipped with tunable multiline argon-ion and krypton-ion lasers, providing the framework for studies requiring simultaneous analysis of four fluorescent gene products within living cells.

3T3 Cells↗

PubMed2000

Effects of KrF excimer laser irradiation on human dental enamel.

Spectra of human dental enamel was recorded in the 200-400 nm UV region. It showed the weak band at 280 nm which were present in enamel protein. Excimer laser are gas lasers which emit light with photochemical decomposition. The wavelength depends on the 248 nm with krypton-fluoride. The enamel surfaces of extracted human teeth were exposed to KrF excimer laser by an energy density range from 29.6 to 3200 J/cm2. The purpose of this study was to investigate the changes with photo chemical reaction in enamel by light microscopy, SEM and X ray diffraction method. Results of analyses suggested that the observed changes of enamel exposed to this laser were the alpha and beta-tricalcium phosphate (TCP) phase in small amounts. No histological changes were observed in grain boundaries of cross sectioned lased enamel under light microscopy. The SEM examination revealed a roughened surface with bubble formation at 800-3200 J/cm2. SEM of etched enamel surface with 0.1 N HCl after laser irradiation at 400-800 J/cm2 showed the extension along the length of the rods. At 1600-3200 J/cm2, there appeared to be a melting of prism structures, because of conversion of photon energy into thermal energy. These results showed the KrF excimer laser irradiation to dental enamel might be a new type of treatment modality and diagnosis in preventive dentistry.

Calcium Phosphates↗

PubMed1991

Parasympathetic denervation of the ciliary muscle following panretinal photocoagulation.

Cynomolgus monkeys underwent unilateral panretinal scatter photocoagulation (PRP) and/or nasal and temporal horizontal retinal meridional photocoagulation (HRMP) with xenon arc or argon or krypton laser light. Shortly thereafter, in the PRP-treated eyes, accommodative responsiveness to topical eserine and electrical stimulation of the Edinger-Westphal nucleus (EWN) was diminished, accommodative responsiveness to intramuscular (i.m.) pilocarpine was enhanced, and the number of muscarinic receptors in the ciliary muscle was reduced compared to the contralateral controls. In most instances, these parameters returned to normal over 6-12 wks and the abnormalities could be induced again by another round of PRP. However, in some PRP-treated eyes, accommodative responsiveness to EWN stimulation and topical eserine remained subnormal permanently (greater than 1 yr). Shortly after HRMP alone, accommodative responses to i.m. pilocarpine, topical eserine, and central stimulation did not differ markedly in the treated and control eyes. Morphologic studies 1 to 78 wk following PRP revealed that myelinated and unmyelinated nerves within the entire circumference of the choroid and ciliary muscle were severely damaged early on. The number of unmyelinated nerves between the individual ciliary muscle fibers was drastically reduced, those which remained were swollen or deteriorated, and agranular synaptic vesicles were rarely seen. Thereafter, the nerves in the choroid and ciliary muscle gradually regenerated. Following HRMP, only the choroidal nerves which passed through the photocoagulated areas and the ciliary muscle nerves in the corresponding meridians showed signs of deterioration, and there was minimal effect on the physiologic responses examined. These findings collectively indicate that intraocular parasympathetic denervation of the ciliary muscle is produced by PRP, although all nerve types are likely damaged.

Accommodation, Ocular↗

PubMed1996

Expression of basic fibroblast growth factor mRNA in developing choroidal neovascularization.

PURPOSE: Basic fibroblast growth factor (bFGF) is an angiogenic peptide that may be important in the pathogenesis of choroidal neovascularization. We attempted to determine the transcription of the bFGF gene during the development of experimentally induced choroidal neovascularization. METHODS: Rat bFGF cDNA was inserted in the pBluescript to prepare antisense and sense riboprobes. Multiple krypton laser burns were applied to the posterior poles of the eyes of pigmented rats according to a protocol described for producing subretinal neovascularization in these animals. At intervals of up to 4 weeks after photocoagulation, the eyes were removed and cut into thin sections. The sections were subjected to histopathological analysis, cell proliferation study, or in situ hybridization with digoxigenin (DIG)-labeled single-strand riboprobes synthesized from rat bFGF cDNA. RESULTS: In normal adult rat retinas, bFGF mRNA expression was mainly observed in the ganglion cell layer and the inner nuclear layer. After laser photocoagulation, proliferation of RPE cells, fibroblast-like cells and cells in the choroid in the lesions were observed. Expression of bFGF mRNA was observed in the lesions 3 days to 2 weeks after laser treatment. Signals of bFGF mRNA were detected in the proliferating RPE-like cells, choroidal vascular endothelial cells and fibroblast-like cells, all of which are essential for neovascularization. However, bFGF mRNA expression was no longer detectable in these cells 4 weeks after photocoagulation. CONCLUSIONS: Our findings indicate that bFGF is normally transcribed in ganglion cells and the inner nuclear cell layer. During the neovascularization that followed laser photocoagulation, bFGF mRNA expression was detected within the laser lesions. It is thus probable that bFGF acts as a mediator in the neovascularization process.

Animals↗

PubMed1982

The effects of ultra-violet laser radiation on cancer.

A group of mice implanted with squamous cell carcinoma (CA1025) and melanoma (B16) were irradiated with a cw krypton laser using 3374A (total dosage 346 j/cm2, and 660 j/cm2), and 3507A (total dosage 367 j/cm2), and a pulse N2 laser 3371a (total dosage 471 j/cm2, 660 j/cm2, and 165 j/cm2). In all groups, tumorous mice were used as controls. Regression of tumors was observed at wavelengths of 3374A and 3371A (total dosage 471 j/cm2 and 660 j/cm2). No regression was observed at 3507A. The regression in some cases was very impressive. The preliminary work on N2 laser irradiation of basal cell carcinoma (in human beings) and of BEL 7404 liver carcinoma cells in vitro and irradiation of one patient with an N2 laser performed in China will also be reported.

Animals↗

PubMedDate not supplied

Choroidal neovascularization in children: report of five cases and literature review.

Choroidal neovascularization is rare in the pediatric population. It has been associated in this age group with a variety of conditions. Increasing ability to treat these neovascular lesions with laser photocoagulation makes early recognition very important for visual preservation. An overview is presented, including an updated list of conditions associated with choroidal neovascularization in children and adolescents. Guidelines to recognition, parent and patient instructions, and the selective use of fluorescein angiography are emphasized. Five illustrative cases are highlighted, including a 10-year-old boy successfully treated with krypton laser photocoagulation near the fovea.

Adolescent↗