| 1. |
- Kronschläger, Martin, et al.
(författare)
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Caffeine eye drops protect against UV-B cataract
- 2013
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Ingår i: Experimental Eye Research. - : Elsevier BV. - 0014-4835 .- 1096-0007. ; 113, s. 26-31
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this study was to investigate if topically applied caffeine protects against in vivo ultraviolet radiation cataract and if so, to estimate the protection factor. Three experiments were carried out. First, two groups of Sprague-Dawley rats were pre-treated with a single application of either placebo or caffeine eye drops in both eyes. All animals were then unilaterally exposed in vivo to 8 kJ/m(2) UV-B radiation for 15 min. One week later, the lens GSH levels were measured and the degree of cataract was quantified by measurement of in vitro lens light scattering. In the second experiment, placebo and caffeine pre-treated rats were divided in five UV-B radiation dose groups, receiving 0.0, 2.6, 3.7, 4.5 or 5.2 kJ/m(2) UV-B radiation in one eye. Lens light scattering was determined after one week. In the third experiment, placebo and caffeine pre-treated rats were UV-B-exposed and the presence of activated caspase-3 was visualized by immunohistochemistry. There was significantly less UV-B radiation cataract in the caffeine group than in the placebo group (95% confidence interval for mean difference in lens light scattering between the groups = 0.10 +/- 0.05 tEDC), and the protection factor for caffeine was 1.23. There was no difference in GSH levels between the placebo- and the caffeine group. There was more caspase-3 staining in UV-B-exposed lenses from the placebo group than in UV-B-exposed lenses from the caffeine group. Topically applied caffeine protects against ultraviolet radiation cataract, reducing lens sensitivity 1.23 times.
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| 2. |
- Kronschläger, Martin, et al.
(författare)
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Evolution of TUNEL-labeling in the Rat Lens After In Vivo Exposure to Just Above Threshold Dose UVB
- 2013
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Ingår i: Current Eye Research. - : Informa UK Limited. - 0271-3683 .- 1460-2202. ; 38:8, s. 880-885
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Tidskriftsartikel (refereegranskat)abstract
- Purpose/Aim:To quantitatively analyse the evolution of TUNEL-labeling, after in vivo exposure to UVB.Methods:Altogether, 16 Sprague Dawley rats were unilaterally exposed in vivo for 15 min to close to threshold dose, 5 kJ/m(2), of ultraviolet radiation in the 300nm wavelength region. Animals were sacrificed in groups of 4 at 1, 5, 24 and 120 h after exposure. For each animal, both eye globes were removed and frozen. The frozen eye was cryo-sectioned in 10 mm thick midsagittal sections. From each globe, three midsagittal sections with at least five sections interval in between were mounted on a microscope slide. Sections were TUNEL-labeled and counter stained with DAPI. For quantification of apoptosis, a fluorescence microscope was used. In sections with a continuous epithelial cell surface, the number of lens epithelial cell nuclei and the number of TUNEL-positive epithelial cell nuclei was counted. The total number of TUNEL-positive epithelial cell nuclei for all three sections of one lens in relation to the total number of epithelial cell nuclei for all three sections of the same lens was compared between exposed and contralateral not exposed lens for each animal.Results:The relative difference of the fraction of TUNEL-positive nuclei between exposed and contralateral not exposed lens increased gradually, peaked in the time interval 5-120 h after exposure, and then declined.Conclusions:Close to threshold dose of UVB induces TUNEL-labeling that peaks in the time window 5-120 h after exposure to UVB.
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| 3. |
- Kronschläger, Martin, et al.
(författare)
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Pharmacokinetics for topically applied caffeine in the rat
- 2014
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Ingår i: Experimental Eye Research. - : Elsevier BV. - 0014-4835 .- 1096-0007. ; 122, s. 94-101
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Tidskriftsartikel (refereegranskat)abstract
- Topically applied caffeine was recently identified as a promising candidate molecule for cataract prevention. Little is known about the pharmacokinetics for topically applied caffeine. Potential toxicity of 72 mM caffeine on the ocular surface and the lens was qualitatively monitored and no toxic effects were observed. The concentration of caffeine was measured in the lens and the blood after topical application of 72 mM caffeine to groups of 10 animals sacrificed at 30, 60, 90 and 120 min after topical application. The lens concentration decreased throughout the observation period while the blood concentration increased up to 120 min. Further, the concentration of caffeine in the lens and blood was measured 30 min after topical application of caffeine, the concentration of caffeine being 0.72, 3.34, 15.51 and 72 mM depending on group belonging, in groups of 10 animals. The caffeine concentration in lens and blood, respectively, increased proportionally to the caffeine concentration topically applied. The rat blood concentrations achieved were far below the equivalent threshold dose of FDA recommended daily dose for humans. This information is important for further development of caffeine eye drops for cataract prevention.
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| 4. |
- Kronschläger, Martin
(författare)
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Prevention of Experimental Cataract Induced by UVR
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Cataract is the leading cause of blindness in the world and is defined by opacification of the normally transparent lens of the eye. The major avoidable cause of cataract is ultraviolet radiation (UVR), but no current strategies have been developed to prevent the onset of cataract. Apoptosis and internal and external antioxidant systems that inhibit apoptosis have been shown to play a significant role in cataractogenesis.The main purposes of this thesis were to study the time evolution of apoptosis, to develop the concept of a protection factor (PF), and to investigate the effect of thioltransferase (Grx1) and topical caffeine in UVR cataract development. Further, to elucidate pharmacokinetics and influence on iris diameter of topical caffeine.Sprague Dawley rats were exposed to UVR and TUNEL staining of the lens sections was analysed. Grx1+/+ and Grx1-/- mice were exposed to 5 sub-doses of UVR. Based on the difference of light scattering between Grx1+/+ and Grx1-/- mice, the concept of the PF was developed. Topical caffeine and a placebo were applied to the eyes of separate groups of Sprague Dawley rats that were exposed to sub-doses of UVR and protective effect was evaluated. Penetration of topical caffeine in Sprague Dawley rats to lens and blood was analysed by high performance liquid chromatography. Pupil diameter was measured in groups of unilaterally and bilaterally caffeine-treated ketamine/xylazine anesthetized Sprague Dawley rats.TUNEL-labeling peaked between 5 and 120 hours after UVR exposure. The PF of Grx1 was 1.3. Moreover, topically administered caffeine protected against UVR-induced cataract development with a PF of 1.23. Topical caffeine peaked at 30 min in the lens, increased up to 120 min in the blood and antagonized ketamine/xylazine-induced mydriasis.In conclusion, UVR induces apoptosis, which is evidenced by the peak of TUNEL-labeling at 24 hours after UVR exposure. The PF is an objective relative measure of protective properties that allows the comparison of different antioxidant systems and administered antioxidant substances. Grx1 and caffeine are protective against UVR-induced cataract. Topically administered caffeine penetrates to the lens and inhibits UVR-induced apoptosis. Additionally, a miotic effect of caffeine is described for the first time.
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| 5. |
- Kronschläger, Martin, et al.
(författare)
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Protective Effect of The Thioltransferase Gene On In Vivo UVR-300 nm Induced Cataract : In vivo protection of Grx1 against UVR in the lens
- 2012
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Ingår i: Investigative Ophthalmology and Visual Science. - : Association for Research in Vision and Ophthalmology (ARVO). - 0146-0404 .- 1552-5783. ; 53:1, s. 248-252
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Tidskriftsartikel (refereegranskat)abstract
- Purpose. To determine the protection factor (PF) for glutaredoxin-1 (Grx1) with regard to UVR-induced cataract by comparison of in vivo ultraviolet radiation (UVR) lens toxicity between double knockout Grx1−/− and Grx1+/+ mice.Methods. Twenty Grx1+/+ mice and 20 Grx1−/− mice were unilaterally exposed in vivo to UVR for 15 minutes. Groups of four animals each received 0.0, 2.1, 2.9, 3.6, and 4.1 kJ/m2 UVR-300 nm. At 48 hours after UVR exposure, light-scattering in the exposed and contralateral nonexposed lenses was measured quantitatively. Macroscopic lens changes were documented with dark-field illumination photography.Results. UVR-300 nm induced subcapsular and cortical cataract in Grx1−/− and Grx1+/+ mice. In both Grx1−/− and Grx1+/+, the light-scattering intensified with increased in vivo exposure doses of UVR-300 nm. The intensity of forward light-scattering was higher in the lenses of Grx1−/− mice than in the lenses of Grx1+/+ mice. The threshold dose for in vivo UVR-300 nm–induced cataract, expressed as MTD2.3:16, was 3.8 in the Grx1+/+ group and 3.0 in the Grx1−/− group, resulting in a PF of 1.3.Conclusions. The PF is an objective relative measure of protective properties. The Grx1 gene is associated with an in vivo PF of 1.3. This result signifies that the presence of the gene allows a 1.3 times longer in vivo exposure to UVR, at equivalent irradiance, than the absence of the gene before early-onset, UVR-induced cataract occurs. This finding indicates the important role of the Grx1 gene in the oxidation defense system of the lens.
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| 6. |
- Kronschläger, Martin, et al.
(författare)
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Topically applied caffeine induces miosis in the ketamine/xylazine anesthetized rat
- 2014
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Ingår i: Experimental Eye Research. - : Elsevier BV. - 0014-4835 .- 1096-0007. ; 127, s. 179-183
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the present study was to examine if topically applied caffeine influences pupil size in ketamine/xylazine anesthetized animals. Two experiments were carried out. In the first experiment, caffeine was topically applied to one of the eyes of 10 ketamine/xylazine anesthetized animals, while vehicle only was topically applied to the contralateral eye. In the second experiment, caffeine was topically applied to both eyes in one group of 10 ketamine/xylazine anesthetized rats, while in another group both eyes vehicle only was topically applied to both eyes. In both experiments pupil diameter was measured at 0, 10, 20, 40 and 60 min after topical application. In three of the animals, the pupil was dilated with tropicamide 5 mg/ml at 60 min after the topical application of caffeine and the pupil diameter was measured. The first experiment showed a relative miosis in caffeine treated eyes as compared to the vehicle treated eye, that changed over time. The second experiment in line with the first experiment, also showed that topically applied caffeine causes a relative miosis as compared to vehicle only that changes over time. Eyes treated with caffeine reacted with quick dilatation after tropicamide application. Topical caffeine antagonizes ketamine/xylazine anesthesia induced mydriasis in a time dependent manner.
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| 7. |
- Meyer, L. M., et al.
(författare)
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Schleimpflug photography detects alterations in corneal density and thickness in patients with dry eye disease
- 2014
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Ingår i: Der Ophthalmologe. - : Springer Science and Business Media LLC. - 0941-293X .- 1433-0423. ; 111:10, s. 914-919
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Tidskriftsartikel (refereegranskat)abstract
- Dry eye disease is a common ocular surface disease that significantly affects the quality of life. Little is known about a potential impact of the disease on corneal morphology. This study was carried out to investigate for the first time if dry eye disease induces changes in corneal density and thickness. In total 97 patients suffering from dry eye disease and 33 healthy age-matched individuals were included in this prospective, randomized study. Corneal morphology was documented with Scheimpflug photography and analyzed for central corneal thickness and corneal density in five anatomical layers (i.e. epithelium, Bowman membrane, corneal stroma, Descemet membrane and endothelium). Corneal density was significantly reduced in the epithelium (p = 0.0053), Bowman membrane (p = 0.0049) and Descemet's membrane (p = 0.0385) in patients with dry eye syndrome compared to healthy controls. This decrease was age-dependant. Furthermore, central corneal thickness was significantly reduced in patients with dry eye syndrome compared to the control group (p = 0.0495). The change was again dependent on age with lower values at higher age. Central corneal thickness increased with age in the control group. The results of this study indicate that corneal morphology is subject to significant alterations in patients with dry eye disease. Scheimpflug photography provides not only unique information in lens trials but is also able to detect changes of corneal anatomy. However, further investigations with other anterior segment imaging techniques, such spectral domain optical coherence tomography (SD OCT/PentacamA (R)) are necessary to further evaluate the clinical consequences of these findings.
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| 8. |
- Meyer, Linda, et al.
(författare)
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Ultrastructure of UVR-B-induced cataract and repair visualized with electron microscopy
- 2014
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Ingår i: Acta Ophthalmologica. - : Wiley. - 1755-375X .- 1755-3768. ; 92:7, s. 635-643
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Tidskriftsartikel (refereegranskat)abstract
- PurposeThe aim of the study is to investigate and visualize the ultrastructure of cataract morphology and repair, after in vivo exposure to double threshold dose UVR-B in the C57BL/6 mouse lens.MethodsTwenty-six-week-old C57BL/6 mice received in vivo double threshold dose (6.4 kJ/m2) UVR-B for 15 min. The radiation output of the UVR-source had λMAX at 302.6 nm. After a latency period of 1, 2, 4 and 8 days following UVR-B exposure, the induced cataract was visualized with electron microscopy techniques. Induced, cataract was quantified as forward lens light scattering. Damage to the lens epithelium and the anterior cortex was investigated with light microscopy in toluidine blue-stained semi-thin sections, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and dark field illumination photography.ResultsUVR-B-exposed lenses developed anterior subcapsular and/or cortical and nuclear cataract after 1 day. Lens light scattering peaked 2 days after exposure. Lens epithelial cell damage was seen in TEM as apoptotic cells, apoptotic bodies, nuclear chromatin condensation, and swollen and disrupted anterior cortex fibres throughout the sections of the whole anterior lens surface. These morphologic changes were also visualized with SEM. Within 8 days, anterior subcapsular cataract was repaired towards the anterior sutures.ConclusionUVR-B exposure of double cataract threshold dose induces a subtotal loss of epithelial cells across the whole anterior surface of the lens. This damage to the epithelium is repaired by epithelial cell movement from the equator towards the lens sutures, thus in retrograde direction to regular epithelial cell differentiation.
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| 9. |
- Söderberg, Per G., et al.
(författare)
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Near infrared radiation damage mechanism in the lens
- 2015
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Ingår i: OPHTHALMIC TECHNOLOGIES XXV. - : SPIE. - 9781628413977
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Konferensbidrag (refereegranskat)abstract
- The current data strongly indicates that there is no photochemical effect of in vivo exposure to 1090 nm near IRR radiation within the pupil. Four groups of 20 Sprague-Dawley rats were unilaterally exposed in vivo to 96 W.cm(-2) centered inside the pupil for 10, 18, 33 and 60 min, respectively depending on group belonging. This resulted in radiant exposure doses of 57, 103, 198 and 344 kJ.cm(-2). Temperature evolution at the limbus during the exposure and difference of intensity of forward light scattering between the exposed and the contralateral not exposed eye was measured at 1 week after exposure. The temperature at the limbus was found to increase exponentially towards an asymptote with an asymptote temperature of around 7 degrees C and a time constant (1/k) of around 15 s. No increase of light scattering was found despite that the cumulated radiant exposure dose was [80; 250] times the threshold for photochemically induced cataract suggested by previous empirical data. It is concluded that at 1090 nm near IRR there is no photochemical effect.
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| 10. |
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| 11. |
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| 12. |
- Söderberg, Per, et al.
(författare)
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Photochemical effects in the lens from near infrared radiation?
- 2009
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Ingår i: Proceedings of SPIE, the International Society for Optical Engineering. - San José, CA : SPIE. - 0277-786X .- 1996-756X. - 9780819474094 ; 7163, s. 716311-
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Tidskriftsartikel (refereegranskat)abstract
- Conclusion: The current data are consistent with a potential photochemical effect of in vivo exposure of the crystalline lens to near infrared radiation since the onset of cataract after in just above threshold dose was at least 18 hrs delayed after the exposure. Materials and methods: The eyes of 6 weeks old Sprague-Dawley rats were exposed unilaterally in vivo to 1090 nm, 6.2 W quasi-top hat spatial distribution with a 3 mm spot on the anterior lens surface within the dilated pupil. First, four exposure time groups of rats were exposed to increasing exposure times. At 24 hrs after exposure, the difference of light scattering between the lenses from the same animal was measured. Then, based on the first experiment, four post-exposure time groups were exposed unilaterally in vivo to 8 s of 1090 nm, 6.2 W quasi-top hat spatial distribution with a 3 mm spot on the anterior lens surface within the dilated pupil. After, the intended post-exposure time, the difference of light scattering between the lenses from the same animal was measured. Results: A 3 mm spot of 6.2 W induces light scattering in the lens with exposures of at least 8 s. Further, after 8 s of 6.2 W within a 3 mm spot on the lens surface, the light scattering increase in the lens was delayed at least 18 hrs after the exposure.
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| 13. |
- Talebizadeh, Nooshin, 1977-, et al.
(författare)
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Modelling the time evolution of active caspase-3 protein in the rat lens after in vivo exposure to Ultraviolet radiation-B : Model for active caspase-3 expression after in vivo exposure to UVR-300 nm
- 2014
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 9:9, s. e106926-
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To introduce a model for the time evolution of active caspase-3 protein expression in albino rat lens up to 24 hours after in vivo exposure to low dose UVR in the 300 nm wavelength region (UVR-300 nm).Methods: Forty Sprague-Dawley rats were unilaterally exposed in vivo to 1 kJ/m2 UVR-300 nm for 15 minutes. At 0.5, 8, 16, and 24 hours after the UVR exposure, the exposed and contralateral not-exposed lenses were removed and processed for immunohistochemistry. The differences in the probability of active caspase-3 expression at four different time points after exposure were used to determine the time evolution of active caspase-3 expression. A logistic model was introduced for the expression of active caspase-3. The parameters for the exposed and the not exposed lenses were estimated for the observation time points.Results: The exposure to UVR-300 nm impacted on the parameters of the logistic model. Further, the parameters of the model varied with time after exposure to UVR-300 nm.Conclusion: The logistic model predicts the impact of exposure to UVR-300 nm on the spatial distribution of probability of active caspase-3 protein expression, depending on time.
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| 14. |
- Talebizadeh, Nooshin, et al.
(författare)
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Objective automated quantification of fluorescence signal in histological sections of rat lens
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Purpose: To develop an automated method to delineate lens epithelial cells and to quantify expression of fluorescent signal of biomarkers in each nucleus and cytoplasm of lens epithelial cells in a histological section.Methods: An automated algorithm was developed in Matlab™ to localize and quantify fluorescence signal in lens epithelial cells in histological images. A region of interest representing the lens epithelium was manually demarcated in each input image. Individual cell nuclei within the region of interest were automatically delineated based on watershed segmentation and thresholding. Fluorescence signal was quantified within nuclei and cytoplasms. The classification of fluorescence signal was based on local background. Classification of cells as labelled or not labelled was thereafter optimized as compared to visual classification of a limited dataset.The performance of the automated classification was evaluated by asking eleven independent blinded observers to classify all cells (n=395) in one lens image. Time consumed by the automatic algorithm and visual /manual classification of nuclei, was recorded.Results: On an average, 77 % of the cells were correctly classified as compared to the majority vote of the visual observers. The average agreement among visual observers was 83 %. However, variation among visual observers was high, and agreement between two visual observers was as low as 71 % in the worst case. Automated classification was on average 10 times faster than manual scoring.Conclusion: The presented method enables objective and fast detection of lens epithelial cells and quantification of expression of fluorescent signal in a histological section of rat lens, with accuracy comparable to the variability between different visual observers. Furthermore, automated scoring is unbiased and reproducible, and results in a 10-fold increase in throughput.
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| 15. |
- Talebizadeh, Nooshin, 1977-, et al.
(författare)
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Objective automated quantification of fluorescence signal in histological sections of rat lens
- 2017
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Ingår i: Cytometry Part A. - : Wiley. - 1552-4922 .- 1552-4930. ; 91:8, s. 815-821
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Tidskriftsartikel (refereegranskat)abstract
- Visual quantification and classification of fluorescent signals is the gold standard in microscopy. The purpose of this study was to develop an automated method to delineate cells and to quantify expression of fluorescent signal of biomarkers in each nucleus and cytoplasm of lens epithelial cells in a histological section. A region of interest representing the lens epithelium was manually demarcated in each input image. Thereafter, individual cell nuclei within the region of interest were automatically delineated based on watershed segmentation and thresholding with an algorithm developed in Matlab™. Fluorescence signal was quantified within nuclei, cytoplasms and juxtaposed backgrounds. The classification of cells as labelled or not labelled was based on comparison of the fluorescence signal within cells with local background. The classification rule was thereafter optimized as compared with visual classification of a limited dataset. The performance of the automated classification was evaluated by asking 11 independent blinded observers to classify all cells (n = 395) in one lens image. Time consumed by the automatic algorithm and visual classification of cells was recorded. On an average, 77% of the cells were correctly classified as compared with the majority vote of the visual observers. The average agreement among visual observers was 83%. However, variation among visual observers was high, and agreement between two visual observers was as low as 71% in the worst case. Automated classification was on average 10 times faster than visual scoring. The presented method enables objective and fast detection of lens epithelial cells and quantification of expression of fluorescent signal with an accuracy comparable with the variability among visual observers.
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| 16. |
- Talebizadeh, Nooshin, 1977-, et al.
(författare)
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Specific spatial distribution of caspase-3 in normal lenses
- 2014
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Ingår i: Acta Ophthalmologica. - : Wiley. - 1755-375X .- 1755-3768. ; 93:3, s. 289-292
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Tidskriftsartikel (refereegranskat)abstract
- PurposeTo determine the distribution of active caspase-3 in rat eye lens epithelium.MethodsIn total, 120 sagittal sections from forty rats were assessed for active caspase-3 labelling using immunohistochemistry. Lens epithelial cells were counted, and the fraction of active caspase-3 labelled cells and their relative positions were identified in each section.ResultsActive caspase-3 is present in normal lens epithelium. The active caspase-3 expression was higher in the anterior pole of the lens. Probability of radial spatial distribution of labelling was fitted with a logistic model. The increase rate and the inflection point were estimated as CI (0.95) to 23 ± 3 cells and 114 ± 3 cells, respectively.ConclusionThe gradually decreasing active caspase-3 labelling from the anterior pole to the periphery suggests that active caspase-3 may be involved in normal protein turnover caused by, for example, incident light.
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| 17. |
- Talebizadeh, Nooshin, et al.
(författare)
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Time evolution of active caspase-3 labelling after in vivo exposure to UVR-300 nm
- 2014
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Ingår i: Acta Ophthalmologica. - : Wiley. - 1755-375X .- 1755-3768. ; 92:8, s. 769-773
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE:To determine the time evolution of active caspase-3 protein expression in albino rat lens after in vivo exposure to low-dose UVR-300 nm, as detected by immunofluorescence.METHODS:Forty Sprague-Dawley rats were unilaterally exposed in vivo to 1 kJ/m2 UVR-300 nm for 15 min. At 0.5, 8, 16 and 24 hr after the UVR exposure, the exposed and contralateral nonexposed lenses were removed and processed for immunohistochemistry. Three mid-sagittal sections from each lens were stained. The cells labelled for active caspase-3 in each section of both the exposed and nonexposed lenses were counted and recorded three times. The difference of the proportion of labelling between the exposed and contralateral nonexposed lenses within each animal was calculated. The differences of active caspase-3 labelling at four different time-points after exposure were used to determine the time evolution of active caspase-3 expression.RESULTS:Caspase-3 expression was higher in the exposed than in contralateral nonexposed lenses. The mean difference between the exposed and contralateral nonexposed lenses, including all lenses from all time intervals, was 0.12 ± 0.01 (= CI 95%). The mean differences between the exposed and contralateral nonexposed lenses were 0.11 ± 0.02, 0.13 ± 0.02, 0.14 ± 0.01 and 0.09 ± 0.03 (= CI 95%) for the 0.5-, 8-, 16- and 24-hr time groups, respectively. The orthogonal comparison showed no difference in the expression of active caspase-3 between the 0.5- and the 24-hr groups (Test statistic 1.50, F1,36 = 4.11, p < 0.05) or between the 8- and the 16-hr groups (test statistic 0.05, F1,36 = 4.11, p < 0.05). There was a difference when comparing the 0.5- and 24-hr groups to the 8- and 16-hr groups (test statistic 7.01, F1,36 = 4.11, p < 0.05).CONCLUSION:The expression of active caspase-3 in the lens epithelium increases after UVR exposure. There is a peak of expression approximately 16 hr after the exposure.
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| 18. |
- Yu, Zhaohua, 1983-, et al.
(författare)
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1090 nm infrared radiation at close to threshold dose induces cataract with a time delay
- 2015
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Ingår i: Acta Ophthalmologica. - : Wiley. - 1755-375X .- 1755-3768. ; 93:2, s. e118-e122
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Tidskriftsartikel (refereegranskat)abstract
- PurposeTo investigate if infrared radiation induced cataract is instant or is associatedwith a time delay between the exposure and the onset of lens light scattering after anexposure to just above threshold dose.MethodsSix-weeks-old albino Sprague-Dawley female rats were unilaterally exposedto 197 W/cm2 infrared radiation at 1090 nm within the dilated pupil. In the firstexperiment, the animals were exposed with four exposure times of 5, 8, 13 and 20 s,respectively. At 24 h after exposure, the light scattering in both exposed andcontralateral not exposed lenses was measured. Based on the first experiment, fourpost exposure time groups were exposed unilaterally to 1090 nm infrared radiation of197 W/cm2 for 8 s. At 6, 18, 55 and 168 h after exposure, the light scattering in bothlenses was measured.ResultsA 197 W/cm2 infrared radiation induced light scattering in the lens withexposures of at least 8 s. Further, after exposure to infrared radiation of 197 W/cm2for 8 s, the light scattering increase in the lens was delayed approximately 16 h afterthe exposure.ConclusionThere is a time delay between the exposure and the onset of cataract afterexposure to close to threshold dose implicating that either near infrared radiationcataract is photochemical or there is a time delay in the biological expression ofthermally induced damage.
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| 19. |
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| 20. |
- Yu, Zhaohua, 1983-, et al.
(författare)
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Measuring temperature in the lens during experimental heat load indirectly as light scattering increase rate
- 2017
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Ingår i: Journal of Biomedical Optics. - 1083-3668 .- 1560-2281. ; 22:1
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Tidskriftsartikel (refereegranskat)abstract
- The current study aims to experimentally estimate the temperature in the lens due to heat load indirectly from the measurement of increase rate of temperature-induced light scattering. The lens was extracted from Sprague-Dawley rats and put into a temperature-controlled cuvette filled with balanced salt solution. Altogether, 80 lenses were equally divided on four temperature groups. Each lens was exposed for 5 minutes to temperature depending on group belonging while the intensity of forward light scattering was recorded. The inclination coefficient of light scattering increase at the temperature 37, 40, 43, and 46 ºC was estimated as a CI(0.95), 3.1±0.8, 4.4±0.8, 5.5±0.9 and 7.0±0.8 x10-4 tEDC/s, respectively. The Arrhenius equation implies that the natural logarithm of the inclination coefficient is linearly dependent on the inverse of the temperature. The proportionality constant and the intercept were 9.6±2.4 x103 K and 22.8±7.7. The activation energy was 8.0±2.0 x101 kJ·mol-1. The current experiment implies that if averaging 20 measurements of inclination coefficients in a new experiment at constant heat load, the confidence limits for predicted temperature correspond to ±1.9 °C. With the proportionality constant and the intercept estimated in the current experiment, the in vivo temperature in the lens can be determined retrospectively with sufficient resolution.
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| 21. |
- Yu, Zhaohua, 1983-, et al.
(författare)
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Ocular temperature elevation induced by threshold in vivo exposure to 1090 nm infrared radiation and associated heat diffusion
- 2014
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Ingår i: Journal of Biomedical Optics. - 1083-3668 .- 1560-2281. ; 19:10, s. 105008-
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Tidskriftsartikel (refereegranskat)abstract
- An in vivo exposure to 197 W/cm2 1090 nm infrared radiation (IRR) requires a minimum 8 s for cataract induction. The present study aims to determine the ocular temperature evolution and the associated heat flow at the same exposure conditions. Two groups of 12 rats were unilaterally exposed within the dilated pupil with a close to collimated beam between lens and retina. Temperature was recorded with thermocouples. Within 5 min after exposure, the lens light scattering was measured. In one group, the temperature rise in the exposed eye, expressed as CI(0.95), was 11±3 ºC at the limbus, 16±6 ºC in the vitreous behind lens and 16±7 ºC on the sclera next to the optic nerve, respectively. In the other group, the temperature rise in the exposed eye was 9±1 ºC at the limbus and 26±11 ºC on the sclera next to the optic nerve, respectively. The difference of forward light scattering between exposed and contralateral not exposed eye was 0.01±0.09 tEDC. An exposure to 197 W/cm2 1090 nm IRR for 8 s induces a temperature increase of 10 °C at the limbus and 26 °C close to the retina. IRR cataract is probably of thermal origin.
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| 22. |
- Yu, Zhaohua, 1983-, et al.
(författare)
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Temperature-controlled in vivo ocular exposure to 1090-nm radiation suggests that near-infrared radiation cataract is thermally induced
- 2015
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Ingår i: Journal of Biomedical Optics. - 1083-3668 .- 1560-2281. ; 20:1
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Tidskriftsartikel (refereegranskat)abstract
- The damage mechanism for near infrared radiation induced (IRR) cataract is unclear. Both a photochemical and a thermal mechanism were suggested.The current paper aims to elucidate a photochemical effect based on investigation of irradiance-exposure time reciprocity.Groups of 20 rats were unilaterally exposed to 96 W/cm2 IRR at 1090 nm within the dilated pupil accumulating 57, 103, 198, 344 kJ/cm2 respectively. Temperature was recorded at the limbus of the exposed eye. Seven days after exposure, the lenses were macroscopically imaged and light scattering was measured quantitatively.The average maximum temperature increase for exposure time 10, 18, 33, 60 minutes was expressed as CI(0.95); 7.0±1.1, 6.8±1.1, 7.6±1.3, 7.4±1.1 ºC at the limbus of the exposed eye. The difference of light scattering in the lenses between exposed and contralateral not exposed eyes was 0.00±0.02, 0.01±0.03, -0.01±0.02, -0.01±0.03 tEDC, respectively and no apparent morphological changes in the lens were observed.An exposure to 96 W/cm2 1090 nm IRR projected on the cornea within the dilated pupil accumulating radiant exposures up to 344 kJ/cm2 does not induce cataract if the temperature rise at the limbus is below 8 °C. This is consistent with a thermal damage mechanism for IRR induced cataract.
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