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PubMed2000

Expression of matrix metalloproteinase-2 (MMP-2) and vascular endothelial growth factor (VEGF) in inflammation-associated corneal neovascularization.

Matrix metalloproteinase-2 (MMP-2), matrix metalloproteinase-9 (MMP-9) and vascular endothelial growth factor (VEGF) are all implicated in the development of neovascularization. To investigate the possible role of these factors in corneal neovascularization we have analysed the expression of MMP-2, MMP-9 and VEGF in a rat model of inflammation-associated corneal neovascularization. In this model, corneal neovascularization was induced in Long-Evans rats by krypton laser photocoagulation whereafter eyes were enucleated at 1, 4, 7, 10 and 20 days. Slit-lamp biomicroscopy and histologic analysis revealed a gradual development of corneal neovascularization that peaked 7-10 days after treatment when newly formed vessels could be seen throughout the corneal surface reaching deep into the stroma. Antisense and sense riboprobes were generated using DNA complementary to MMP-2, MMP-9 and VEGF, and mRNA expression was analysed using in situ hybridization. The expression of MMP-2 and MMP-9 in untreated corneas was low or absent whereas VEGF was weakly expressed in the corneal epithelium. MMP-2 expression was increased during corneal neovascularization and was mainly localized to the cells infiltrating areas of new vessel formation. Many of these cells appeared to be inflammatory cells. VEGF expression had a similar overall distribution to MMP-2 during neovascularization with the exception that its expression in the corneal epithelium remained and even increased slightly. MMP-9 was prominently expressed at the border of regenerating corneal epithelium in areas with epithelial wounding but was not detected in the vascularized stroma. Together, the results of the present study support a role for MMP-2 and VEGF in inflammation-associated corneal neovascularization whereas MMP-9 instead appears to be involved in corneal epithelial wound-healing.

Animals↗
PubMed1998

Tunable Far-Infrared Spectroscopy of 82KrD+, 84KrD+, 86KrD+, and 82KrH+

Pure rotational spectra of isotopic species of protonated krypton 82KrD+, 84KrD+, 86KrD+, and 82KrH+ were observed in the 0.75-3.5 THz region, using a tunable far-infrared radiation source. Rotational parameters B, D, and H of these molecular ions were determined. By analyzing the observed frequencies with the previous data on all the isotopic species, the mass independent Dunham parameters Ukl, DeltaKrkl, and DeltaHkl have been improved. Copyright 1998 Academic Press.

Journal Article↗
PubMed2000

Quantum Number Dependence of Lineshift Coefficients Induced by Collisions with Noble Gas Perturbers in the nu(3) Band of NO(2).

To complete our study concerning lineshift in the rovibrational spectrum of (14)N(16)O(2), a pulse-driven three-channel lead salt diode laser spectrometer was applied to record high-resolution spectra at room temperature in the 6.2-µm region corresponding to the nu(3) band at low NO(2) concentrations. The shift was studied for collisions with the noble gases He, Ne, Ar, Kr, and Xe. This paper extends our recently published data in order to analyze the quantum number dependence of the shift effect more precisely. Therefore, in this paper, additionally eight unresolved NO(2) doublets covering an enlarged quantum number range (10 </= N(") </= 34, 2 </= K(")(a) </= 6) were studied. For all doublets, shift coefficients delta(NO(2)-noble gas) and additionally broadening coefficients gamma(NO(2)-noble gas) were determined. Hereby, the experimental data confirm general trends published recently. In this study, in the case of broadening for the lighter rare gases helium, neon, and argon, only a slight decrease of gamma(NO(2)-noble gas) was observed, whereas for the rare gases with a higher atomic weight, i.e., krypton and xenon, a pronounced decrease of gamma(NO(2)-noble gas) with increasing rotational quantum number N(") occurred. All measured lineshift coefficients were negative. The absolute value of the determined lineshift coefficient ||delta(NO(2)-noble gas) || increases with the mass of the noble gas perturber, i.e., ||delta(NO(2)-He) || < ||delta(NO(2)-Ne) || < ||delta(NO(2)-Ar) || < ||delta(NO(2)-Kr) || < ||delta(NO(2)-Xe) ||. Within the studied quantum number range, an increase ||delta(NO(2)-noble gas) || with increase of N(") was observed. A typical trend of the shift and broadening data on the quantum number K(")(a) was not observed. Copyright 2000 Academic Press.

Journal Article↗
PubMed1994

Double-label immunofluorescence with the laser scanning confocal microscope using cyanine dyes.

The laser scanning confocal microscope, when used with the krypton-argon ion laser, is well suited for the simultaneous detection of pairs of antigens by immunofluorescence. Traditionally, double-label studies have utilized secondary antibodies conjugated to fluorescein isothiocyanate (FITC), excited by the 488-nm line (blue), and to tetramethyl rhodamine isothiocyanate or Texas Red, excited by the 568-nm line (yellow). However, the use of fluorophores excited by the 488 nm line produces unsatisfactory results when tissue contains low wavelength-excitable autofluorescence. In the amphibian cardiac ganglion, for example, autofluorescent granules within parasympathetic neurons obscure cell surface-derived signals and prevent one from analyzing the relative position of acetylcholine receptor clusters and synaptic boutons by double-label immunofluorescence. This problem has been solved by using cyanine 3.18 (Cy3)- and cyanine 5.18 (Cy5)-conjugated secondary antibodies, which are excited efficiently by the 568-nm (yellow) and the 647-nm (red) lines and which emit in the orange/red and in the far-red, respectively, and thus by avoiding the 488-nm line altogether. The resulting images are as good or better than those obtained with FITC and Texas Red, even without consideration of autofluorescence.

Animals↗
PubMedDate not supplied

Diode laser photocoagulation of choroidal neovascular membranes.

BACKGROUND: Krypton or argon laser treatment of choroidal neovascularization (CNV) has been shown to be effective in reducing the incidence of severe visual loss. The usefulness of diode laser in the treatment of many chorioretinal disorders is currently under evaluation. METHODS: Our study involved 42 eyes of 41 patients affected with CNV which were treated with a near infrared diode laser. RESULTS: The mean follow-up was 10.12 months. Visual acuity improved in 12 eyes (28.6%), did not change in 17 eyes (40.5%) and worsened in 13 eyes (30.2%). Mean visual acuity before treatment was 0.23 and 0.21 after treatment. Recurrent CNV was seen in 13 eyes. In a subgroup of 24 well-defined juxtafoveal or extrafoveal CNVs which underwent direct photocoagulation visual acuity improved in 8 eyes (33.3%), was unchanged in 11 (45.8%) and worsened in 5 (20.9%). Five eyes showed recurrent CNV. CONCLUSIONS: Our results appear to support the use of diode laser in the treatment of CNVs. The deeper penetration into the choriocapillaris of the diode wavelength could be effective in blocking CNV by inducing a more extensive chorioretinal atrophy.

Adult↗
PubMed1991

The effect of wavelength on glial fibrillary acidic protein immunoreactivity in laser-induced lesions in rabbit retina.

Rabbit retinas were treated with low-intensity laser coagulation at five different wavelengths. Using an indirect immunocytochemical method, the retinas were stained for glial fibrillary acidic protein (GFAP) at 2, 4, 21 and 32 days after coagulation such that we could follow GFAP expression in the Müller cells during retinal repair. GFAP-positive staining was found in the end feet of the Müller cells at 2 days after laser coagulation. GFAP immunoreactivity was observed throughout the Müller cells, surrounding the central necrotic tissue, at days 4, 21 and 32 after laser coagulation. Scar tissue in the subretinal space at days 21 and 32, which was more pronounced for the longer wavelengths produced by the Krypton and Nd-YAG lasers, also showed GFAP immunoreactivity. The Müller cells remained GFAP-immunoreactive for at least 32 days after laser coagulation.

Animals↗
PubMed1996

Vitreous laser absorption following fluorescein angiography in diabetic patients.

BACKGROUND: Sodium fluorescein staining of the vitreous following fluorescein angiography may interact with laser photocoagulation. METHODS: We evaluated the laser absorption by fluorescein in the vitreous when photocoagulation is performed following fluorescein angiography in 15 eyes of nine diabetic patients. Axial fluorescein concentration in the vitreous was measured by a scanning vitreal fluorophotometer. The amount of light absorbed by the fluorescein within the vitreous was calculated according to the Lambert-Beer law. RESULTS: The mean fluorescein concentration ranged from 2.93 ng cm-3 to 105.16 ng cm-3 at 1 h after injection of fluorescein and from 8.03 to 188.56 ng cm-3 after 4 h. Maximum laser absorption at 488 nm ranged from 6.79% (after 1 h) to 14.53% (after 4 h); at 514.5 nm it ranged from 0.96% to 2.14%; at 532 nm it ranged from 0.03% to 0.07%. At lambda > 550 nm, laser absorption was found to be negligible. CONCLUSIONS: In order to optimize the effect of photocoagulation, especially during long photocoagulation sessions, argon blue laser (488 nm) should be avoided following fluorescein angiography. Argon green laser (514.5 nm) should be used within 1 h after fluorescein injection. Frequency-doubled Nd:YAG laser (532 nm), krypton laser (647 nm) or semiconductor diode laser (810 nm) may be used at any time.

Absorption↗
PubMed1996

Immunolocalization of basic fibroblast growth factor during wound repair in rat retina after laser photocoagulation.

BACKGROUND: Basic fibroblast growth factor (bFGF) stimulates the mitogenesis of various cells and plays a key role in wound repair. We studied the immunohistochemical localization of bFGF during wound repair in the rat retina after laser photocoagulation. METHODS: Krypton laser photocoagulation was performed on the eyes of pigmented rats. The eyes were enucleated on days 1, 3, 7, 14 and 28 after the photocoagulation, and the immunohistochemical localization of bFGF was assessed. Two different monoclonal antibodies and one polyclonal antibody against bFGF as first antibodies were used. RESULTS: Marked immunoreactivity for bFGF was found in the ganglion cell layer, and weak immunoreactivity for bFGF was found in the retinal pigment epithelial (RPE) cells of the normal adult rat retina. On day 3 after laser photocoagulation, the nuclei and cytoplasm of proliferating RPE cells at the center of the photocoagulated lesion showed intense bFGF immunoreactivity. The nuclei of RPE cells around the lesion showed intense bFGF immunoreactivity. Macrophages that migrated into the lesion showed positive staining for bFGF. These immunoreactivity decreased with time. Controls (0.05 M Tris-HCl buffer, normal serum, or these same antibodies preabsorbed with bFGF) did not show positive staining. CONCLUSION: The finding of an elevated expression of bFGF immunoreactivity in the photocoagulated lesion suggests that bFGF may play a role in wound repair in the rat retina after laser photocoagulation.

Animals↗
PubMed1993

Intrapulmonary gas mixing and pulmonary gas exchange in artificially ventilated dogs.

To investigate the effect of incomplete gas mixing between tidal air and residual gas on pulmonary gas exchange, anaesthetized dogs were ventilated artificially with breathing patterns with different durations of the post-inspiratory apnoea (ta = 0, 0.5, 1.0 and 2.0 s), where tidal volume, breathing frequency, inspiratory and expiratory flow patterns were kept constant. We determined the alveolar ventilations (VA) of He and SF6 from the product of end-expiratory lung volume (VL,E') and specific ventilation (VA/VL,E'). VL,E' was determined by the dilution technique and the specific ventilations of the two gases were obtained from their multiple-breath washout. Further, tracer amounts of acetone, ether and enflurane were infused continuously into a peripheral vein and a bolus of a gas mixture of krypton, Freon12 and SF6 was introduced into the peritoneal cavity. We determined the Excretion (E) and Retention (R) of these six gases according to the multiple-inert-gas-elimination technique (MIGET). VA increased with increasing ta, where VA,He was about 14% larger than VA,SF6. For both gases, however, the increase in VA relative to control (VA for ta = 0) was virtually the same: 9, 11 and 19% (mean values) for ta = 0.5, 1.0 and 2.0 s respectively. For all dogs the E/R curve shifted to larger E values with increasing ta. E for the most soluble tracer gas (acetone) increased by 11, 21 and 25% for ta = 0.5, 1.0 and 2.0 s respectively. VA, determined with MIGET from the ventilation/perfusion distribution, increased by almost the same percentages.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetone↗
PubMed1995

Intrapulmonary gas mixing and dead space in artificially ventilated dogs.

In this study we have investigated the effects of breath holding and of the physical properties of gases on four different respiratory dead spaces (VD): the Fowler, the physiological, the washout and the inert gas dead space. The experiments were performed with dogs which were ventilated artificially with breathing patterns with different post-inspiratory breath holding times (ta) of 0, 0.5, 1.0 and 2.0 s. Tracer amounts of acetone, ether and enflurane were infused continuously into a peripheral vein and a bolus of a mixture of krypton, Freon12 and SF6 was introduced into the peritoneal cavity. After reaching steady state, samples of arterial blood, mixed venous blood and mixed expired air were taken simultaneously. From the partial pressures (Pa, PV and PE respectively) we determined the excretion (E = PE/PV), retention (R = Pa/PV) and the physiological dead space fraction (VD,phys/VT = (1- PE/Pa)) for each gas, where VT is tidal volume. Further, we recorded the expirograms of the six tracer gases and of CO2 from which the Fowler dead space fractions (VD,Fowler/VT) of the different gases were determined. Also the washout dead space fractions (VD,washout/VT) for He and SF6 were determined as well as the inert gas dead space fraction (VD,MIGET/VT) with the use of the multiple inert gas elimination technique (MIGET). With the exception of VD,phys/VT for SF6, all dead space fractions decreased with increasing ta. VD,phys/VT for the poorly soluble gas SF6 was considerably larger than VD,phys/VT for the remaining gases. For the highly soluble acetone VFowler/VT was considerably smaller than VD,Fowler/VT for the other gases. VD,washout,SF6/VT was always larger than VD,washout,He/VT and VD,Fowler,SF6/VT. Further, VD,phys/VT was larger than VD,Fowler/VT for SF6 and acetone. However, for gases with intermediate solubility in blood VD,phys/VT tended to be smaller than VD,Fowler/VT. We conclude that the respiratory dead spaces are affected by the breathing pattern and by the physical properties of gases, i.e. their diffusivity in alveolar gas and their solubility in blood or lung tissue.

Animals↗
PubMed1988

Right ventricular performance and pulmonary haemodynamics in adolescent and adult patients with cystic fibrosis.

A combined haemodynamic and radionuclide approach was used to evaluate right ventricular performance in 16 adolescent and adult patients with cystic fibrosis (CF). There were nine patients with mild arterial hypoxaemia (PaO2 greater than 80% of predicted) and normal resting pulmonary artery pressure and seven patients with severe arterial hypoxaemia (PaO2 less than 70% of predicted) and resting pulmonary arterial hypertension (PH). The right ventricular ejection fraction (RVEF) by equilibrium angiocardiography using krypton 81m as a tracer and stroke volume index (SVI) by thermodilution techniques were measured simultaneously and right ventricular end-diastolic and end-systolic volumes were derived. RVEF was normal in CF patients without PH (58.9 +/- 7.2%) but was reduced in those with PH (45.4 +/- 2.6%). There was a statistically significant inverse linear correlation between RVEF and afterload as assessed by mean pulmonary artery pressure (Pap: r = -0.76) and pulmonary vascular resistance (PVR: r = -0.78), indicating that RVEF ist afterload-dependent. Right ventricular function, however, as assessed by right ventricular end-systolic pressure-volume relations was even higher in CF patients with PH, indicating preserved or even increased right ventricular function in the face of an increased afterload stress.

Adolescent↗
PubMed1989

Experimental photoablation of meniscus cartilage by excimer laser energy. A new aspect in meniscus surgery.

Excimer lasers have been demonstrated to provide a very precise and circumscribed ablation of synthetic polymers and biological tissues. We investigated in vitro the use of ultrashort pulsed ultraviolet excimer-laser energy for controlled removal of meniscus cartilage under the aspects of arthroscopic meniscectomy. A krypton-fluorine gas mixture was used to achieve laser emission of 248-nm wavelength. A total of 22 human menisci obtained either by operation or necropsy were irradiated over a range of energy fluence (2.15-3.07 J/cm2/pulse), repetition rates (5-20 Hz), and exposure time (15-60s). Ablation rates of 4.00-5.76 microns per pulse were obtained. Light-microscopic examinations demonstrated tissue ablation without any evidence of pathological changes associated with continuous-wave laser irradiation. Effects of laser energy were clearly limited to the target of the laser beam, and tissue removal proceeded without production of heat or smoke. Due to the lack of pathological alterations observed, excimer-laser irradiation of meniscus cartilage may prove to be advantageous for precisely cutting and removing menisci without injury to the surrounding normal tissue. Clinical application of excimer-laser irradiation includes the development of suitable fiberoptics and laser coupling, as well as modification of fiber tips.

Humans↗
PubMed1992

Induction of SOS repair by ionizing radiation. Results from experiments at accelerators.

beta-galactosidase and alkaline phosphatase activities of Escherichia coli strain PQ37 carrying the fusion gene of sulA and lacZ treated with different types of ionizing radiation were examined. The induction factor (ratio of beta-galactosidase to alkaline phosphatase activity), reflecting the SOS-induction potency, increases significantly with radiation dose. Maximum effectiveness to induce SOS-response has been found for deuterium and helium ions in comparison to gamma-rays, carbon or krypton ions. Increased energy of helium ions leads to greater SOS-induction potency of radiation.

Dose-Response Relationship, Radiation↗
PubMed1976

Nuclear energy: health impact of carbon-14.

Estimates are presented on the carbon-14 generation rates in several reactor types and in peaceful nuclear explosions. If the carbon-14 generated in light water reactors is released, the population radiation dose rate it causes initially will be comparable to that resulting from the krypton-85 and tritium generated in these reactors. Because of the long half-life, the radiation dose commitment and the dose rate resulting from the environmental build-up of carbon-14 are considerably larger than those of the two other radionuclides.

Air Pollution, Radioactive↗
PubMed1996

A dual fluorescence technique for visualization of Staphylococcus epidermidis biofilm using scanning confocal laser microscopy.

A new dual fluorescence technique is described which, when combined with scanning confocal laser microscopy (SCLM), can be used to visualize the components of biofilm produced by Staphylococcus epidermidis. Chemostat cultures of RP62A (a well-characterized slime-producing strain of S. epidermidis) were used to produce mature biofilm on polyvinylchloride (PVC) disks immobilized in a modified Robbins device using a 'seed' and 'feed' model system. Serial horizontal and vertical optical thin sections, as well as three-dimensional computer reconstructions, were obtained on in situ biofilm using the dual fluorescence procedure. Bacteria were visualized by green autofluorescence excited at 488 nm with an Argon laser. Cell-associated and exocellular matrix material (slime) was visualized by red fluorescence excited at 568 nm with a Krypton laser after interaction of the biofilm with Texas Red-labeled wheat germ agglutinin which is a slime-specific lectin marker. Structural analysis revealed that the cocci grew in slime-embedded cell clusters forming distinct conical-shaped microcolonies. Interspersed open channels served to connect the bulk liquid with the deepest layers of the mature, hydrated biofilm which increased overall surface area and likely facilitated the exchange of nutrients and waste products throughout the biofilm. The combined dual fluorescence technique and SCLM is potentially useful as a specific noninvasive tool for studying the effect of antimicrobial agents on the process of biofilm formation and for the characterization of the architecture of S. epidermidis biofilm formed in in vivo and in vitro on medical grade virgin or modified inert polymer surfaces.

Biofilms↗
PubMed1997

Vascular endothelial growth factor expression in choroidal neovascularization in rats.

BACKGROUND: The pathogenesis of choroidal neovascularization is largely unknown. We investigated vascular endothelial growth factor (VEGF) expression in laser-induced choroidal neovascularization (CNV) in rats. METHODS: Intense krypton laser photocoagulation was applied to the posterior poles of the eyes of pigmented rats to induce CNV, which was confirmed by fluorescein angiography and histopathology. The eyeballs were enucleated 1, 3, 7, 14 and 28 days after laser photocoagulation. Cryostat sections were prepared for immunofluorescence staining using anti-VEGF and macrophage marker (ED1) antibodies. The posterior segments of eyeballs pooled from photocoagulated and control rats were submitted for immunoprecipitation and immunoblotting by the anti-VEGF antibody, and reverse transcriptase-polymerase chain reaction (RT-PCR) amplification of VEGF mRNA. RESULTS: Very weak immunoreactivity for anti-VEGF antibody was found in the ganglion cell layer, inner nuclear layer, and retinal pigment epithelium (RPE) in the normal retina. In the development of CNV, strong positive staining for anti-VEGF antibody was found in photocoagulated areas in the subretinal space and choroid. Double immunofluorescence staining showed that many cells in lasered lesions were positive both for anti-VEGF and macrophage marker ED1 antibody staining in the early stage of this model. Immunoblots showed a positive band for the VEGF molecule in treated but not control animals. RT-PCR results demonstrated upregulation of VEGF transcripts in the CNV model compared with normal animals. CONCLUSIONS: Our findings showed the upregulation of VEGF expression in experimentally induced CNV, where it may be involved in promoting choroidal angiogenesis. Macrophages may be one of the main sources of VEGF in the early stage of the disease.

Animals↗
PubMed1986

Low-energy long-exposure laser therapy in the management of choroidal melanoma.

Low-energy (0.2-0.4 W) long-exposure (10-30 s) argon green and krypton red laser applications were used in the treatment of 29 selected choroidal melanomas. In 11 cases laser treatment was the only therapy used. In 18 cases laser was used as an adjunct to local surgical resection of the tumour. The technique gives promise of being useful in the management of relatively flat choroidal melanomas of up 4 mm in thickness.

Choroid Neoplasms↗
PubMed1986

The treatment of difficult retinal detachments with an expanding gas bubble without vitrectomy.

In a prospective study on the use of perfluorocarbon gases (CF4, C2F6, C3F8) without prior mechanical vitrectomy, 51 retinal detachments that were not suitable for scleral buckling were treated by injection of a small bubble of gas into the vitreous to form a tamponade. There were 23 patients with giant tears, 16 with posterior holes, 9 with breaks at different latitudes, and 3 in whom the gas was used for diagnostic purposes. The gases were sustained at therapeutic volumes for 10-70 days. The tears were sealed with argon or krypton laser. The overall reattachment rate was 71%. Postoperative visual acuity improved or remained the same in all patients with reattached retina. In a follow-up of 1 year-38 months there were no late complications, such as cataract, glaucoma, keratopathy, or subsequent visual deterioration.

Adolescent↗