| 1. |
- Dong, Xiuqin, et al.
(författare)
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Maximum tolerable dose for avoidance of cataract after repeated exposure to ultraviolet radiation in rats
- 2007
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Ingår i: Experimental Eye Research. - : Elsevier BV. - 0014-4835 .- 1096-0007. ; 84:1, s. 200-208
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of the present study was to determine the impact of inter-exposure interval between repeated equivalent exposures of ultraviolet radiation (UVR) on threshold accumulated dose for cataract development. Female Sprague-Dawley rats were randomly divided into 5 inter-exposure interval groups with 20 rats in each group. The inter-exposure intervals were 6 h, 1, 3, 9 and 30 days respectively. Each inter-exposure interval group was divided into 5 dose-subgroups. Only one eye of each rat was exposed to ultraviolet radiation (lambdamax=300 nm). The total dose incident on the cornea, in each subgroup varied between 0 approximately 10 kJ/m2. One week after the second exposure, the rats were sacrificed and both lenses were extracted. The intensity of forward light scattering was measured and macroscopic morphology was documented. Maximum tolerable dose (MTD) for each inter-exposure interval was estimated based on the experimentally determined dose-response function. The difference of intensity of light scattering between exposed and contralateral non-exposed lens decreased as a function of inter-exposure interval between the two equivalent exposures. The accumulated MTD2.3:16 was 5.3, 5.1, 5.4, 5.8, and 6.0 kJ/m2 UVR-B for the 6 h, 1, 3, 9 and 30 day inter-exposure interval between the two exposures, respectively. The shorter the inter-exposure interval between two subsequent exposures, the more damage. The time constant for repair of lens damage after in vivo exposure to close to threshold dose was estimated to be eight days and the fraction of repairable damage to be 20%. The accumulated threshold dose for damage after two repeated equivalent exposures to UVR-B increases as a function of inter-exposure interval up to at least 30 days inter-exposure interval.
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| 2. |
- Dong, Xiuqin, et al.
(författare)
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Maximum tolerable dose for avoidance of cataract induced by ultraviolet radiation-B for 18 to 60 week old rats
- 2005
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Ingår i: Experimental Eye Research. - : Elsevier BV. - 0014-4835 .- 1096-0007. ; 80:4, s. 561-566
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of the present study was to investigate the maximum tolerable dose for avoidance of UVR-B-induced cataract in rats in the age interval 18-60 weeks and establish the functional relationship between age and sensitivity to UVR-B. Four groups of 20 albino Sprague-Dawley rats each, aged 18, 26, 40 or 60 weeks, were included. Each age group was divided into five UVR dose sub-groups. The rats were unilaterally exposed to ultraviolet radiation (lambda(max)=302.6 nm, lambda0.5=4.5 nm). The incident dose on the cornea varied between 0 and 9.2 kJ m(-2). One week after exposure, the rats were sacrificed and both lenses were extracted. The intensity of forward light scattering was measured and photographs were taken. The functional relationship between age and sensitivity to UVR-B was estimated as the maximum tolerable dose based on rats age from 3 to 60 weeks. The maximum tolerable dose for 18, 26, 40, and 60 weeks, respectively, was estimated to 5.2, 4.9, 4.7, and 5.1 kJ m(-2). The sensitivity to UVR-B for Sprague-Dawley rats increases with increasing age during the first third of the rat life span, and then stabilizes to a constant level during the remaining two-thirds.
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| 3. |
- Dong, Xiuqin
(författare)
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Safety limit estimation for cataract induced by ultraviolet radiation
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background: Ultraviolet radiation (UVR) is considered one of the major risk factors for agerelated cataract. UVR-induced cataract follows a continuous dose-response function. The concepts maximum acceptable dose (MAD) and its improvement, maximum tolerable dose (MTD), were developed for estimation of threshold dose for avoidance of UVR-induced cataract. The present report details the results of our research investigating the impact of age, exposure time, and interexposure interval for double exposures on threshold dose. Methods: Lenses from female Sprague-Dawley outbred rats were exposed to UVR type B (UVR-B). The radiation from a high-pressure mercury arc lamp was collimated, passed through a water filter and a double monochromator (lambda(max) =300 nm), and projected in vivo on the cornea or in vitro on the anterior surface of lens. One week after in vivo UVR-B exposure, extracted lenses were photographed and forward light scattering was measured. After in vitro UVR-B exposure, both exposed and nonexposed lenses were cultured. The intensity of forward light scattering was measured daily during week 1 and every second day during weeks 2 and 3. Morphologic changes were documented. Results: The MAD for 3-week-old rats was almost 3 times lower than that for 18-week-old rats (study I). Rats aged 18 to 60 weeks had a stable MTD of approximately 5 kJ/m2 (study II). The data from rats aged 3 to 60 weeks were used to derive a general expression for threshold dose (MTD) as a function of rat life span. It was shown that MTD increases with increasing age in the first third of the life and then remains stable for the remaining two thirds of the life span. The study of lenses exposed in vitro to UVR-B proved that the sensitivity difference between young and old rats does not depend on age-related anatomic differences (study III). With varying exposure times (7.5, 15, 30, 60, or 120 minutes), it was found that there was a lowest threshold dose at 15 minutes of UVR-B exposure (study IV). When varying intervals between 2 repeated exposures at a constant UVR-B dose, it was found that the 1 day interexposure interval was associated with a lower threshold dose than the interexposure intervals 6 hours, and 1, 3, 9, and 30 days (study V).
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| 4. |
- Dong, Xiuqin, et al.
(författare)
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The effect of exposure time on maximum acceptable dose for avoidance of ultraviolet radiation-induced cataract
- 2005
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Ingår i: Ophthalmic Research. - : S. Karger AG. - 0030-3747 .- 1423-0259. ; 37:4, s. 197-201
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Tidskriftsartikel (refereegranskat)abstract
- The effect of exposure time on maximum acceptable dose (MAD) for avoidance of ultraviolet radiation B (UVRB)-induced cataract was investigated. Sprague-Dawley rats were divided into 5 exposure time groups: 7.5, 15, 30, 60, and 120 min. Each exposure time group was divided into 5 dose subgroups: 0, 1, 2, 4, and 8 kJ/m2. The rats were unilaterally exposed to UVR around 300 nm. One week after the exposure, macroscopic structure was recorded and lens forward light scattering was measured. MAD for avoidance of UVRB-induced cataract was estimated based on the dose-response function. MAD for avoidance of UVRB-induced cataract for 7.5, 15, 30, 60, and 120 min exposures was estimated to be 2.0, 1.4, 1.9, 1.8 and 2.2 kJ/m2, respectively. In the exposure time domain 7.5-120 min, MAD for avoidance of UVRB-induced cataract depends on exposure time.
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| 5. |
- Meyer, Linda M., et al.
(författare)
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Dose dependent cataractogenesis and Maximum Tolerable Dose (MTD(2.3:16)) for UVR 300 nm-induced cataract in C57BL/6J mice
- 2008
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Ingår i: Experimental Eye Research. - : Elsevier BV. - 0014-4835 .- 1096-0007. ; 86:2, s. 282-289
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of the present study was to investigate the in vivo dose response function for UVR 300 nm-induced cataract in the C57BL/6J mouse lens and to establish a cataract threshold estimate expressed as Maximum Tolerable Dose (MTD(2.3:16)) for UVR 300 nm-induced cataract in the C57BL/6J mouse lens. Knowledge of the MTD(2.3:16) in the C57BL/6J mouse will permit quantitative in vivo comparison of UVR-B threshold sensitivity of knockout mice, e.g. animals deficient in key antioxidative enzymes or mice suffering from genetically predetermined eye disease, to wild type animals. Eighty C57BL/6J mice were divided into four dose groups. The animals were exposed unilaterally to 0, 2, 4, or 8 kJ/m(2) UVR 300 nm for 15 min (n=20). The radiation output of the UVR-source had lambda(max) at 302.6 nm with 5 nm full width at half maximum. Two days after exposure cataract was quantified as forward lens light scattering intensity in the exposed and the contralateral non-exposed lens. Morphological lens changes were documented using grid and dark field illumination photography. MTD(2.3:16) was estimated from the forward light scattering measurements. Two days after exposure mainly anterior subcapsular but also cortical and nuclear cataract developed in lenses that had received 2, 4, and 8 kJ/m(2) UVR 300 nm. Forward light scattering intensity increased with increasing UVR 300 nm dose. MTD(2.3:16) for the mouse lens was estimated to 2.9 kJ/m(2) UVR 300 nm. Lens light scattering intensity in the C57BL/6J mouse lens increases with UVR 300 nm in vivo dose in the range 0-8 kJ/m(2). The MTD(2.3:16) of 2.9 kJ/m(2) in the C57BL/6J mouse lens determined here, is essential to quantify and compare in vivo the impact of genetic modulation on lens susceptibility to oxidative stress and plan dose-ranges in future investigations of UVR 300 nm-induced cataract pathogenesis.
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| 6. |
- Meyer, Linda M., et al.
(författare)
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Light scattering in the C57BL/6 mouse lens
- 2007
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Ingår i: Acta Ophthalmologica Scandinavica. - : Wiley. - 1395-3907 .- 1600-0420. ; 85:2, s. 178-182
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE To characterize inherent light scattering in the C57BL/6 mouse lens. METHODS Lenses from 20 6-week-old female C57BL/6 mice were extracted from freshly enucleated globes and microsurgically cleaned of remnants of the ciliary body. Lens light scattering was measured quantitatively with a light dissemination meter (LDM). Morphological properties of the mouse lenses were documented using grid- and dark-field illumination photography. Analysis of variance was performed to establish variance for animals, variance between left and right eyes and variance for measurements. RESULTS Average inherent light scattering in the C57BL/6 mouse lens is 0.16 +/- 0.02 tEDC (transformed equivalent diazepam concentration). The mean size of a mouse lens at 6 weeks is 1.9 mm in diameter. Two lenses featured pre-existing cortical lens opacities. Variance for animals was assessed to be 7.9 10(- 4) tEDC(2), variance for measurements was 1.6 10(- 4) tEDC(2), and variance between left and right eyes was 8.8 10(- 4) tEDC(2). The tolerance limit for non-pathological light scattering was determined to 0.26 tEDC. No significant difference in light scattering between left and right mouse lenses was found. The minimum number of C57BL/6 mice required for detection of a 10% experimentally induced change in light scattering intensity was estimated to be 50 for independent group experiments and 25 for paired design experiments. CONCLUSIONS The C57BL/6 mouse is a suitable animal in which to conduct experiments on light scattering or cataractogenesis with high precision at reasonable sample sizes. Before including C57BL/6 mice into a study on cataractogenesis, pre-existing lens opacities such as congenital cataract must be excluded.
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| 7. |
- Meyer, Linda M., et al.
(författare)
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UVR-B induced cataract development in C57 mice
- 2005
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Ingår i: Experimental Eye Research. - : Elsevier BV. - 0014-4835 .- 1096-0007. ; 81:4, s. 389-394
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Tidskriftsartikel (refereegranskat)abstract
- The evolution of the morphological appearance and intensity of light scattering in C57 mice lenses after exposure to ultraviolet radiation type B (UVR-B) was investigated. A total of 80, 6-week-old female C57BL/6 mice were divided into four groups (n=20). One eye in each animal was exposed in vivo to UVR-B in the 300 nm wavelength region (UVR-B-300 nm) to a dose of 5 kJm(-2) for 15 min. The radiation output had lambda(max) at 302 nm with 5 nm [FWHM]. The animals were consecutively sacrificed at 1, 2, 4 and 8 days after the exposure. Macroscopic lens changes were documented using grid- and dark field illumination photography. Light scattering in the exposed and contralateral not exposed lens was measured quantitatively. Morphological lens changes were documented using grid- and dark field illumination photography. In vivo exposure to UVR-B-300 nm induced subcapsular cataract in all exposed lenses and occasionally cortical and nuclear cataract at all investigated time points. Exposed lenses scattered light significantly higher on all investigated days compared to contralateral non-exposed lenses. A transient increase of light scattering peaking at day 2 in exposed as well as in contralateral not exposed lenses was identified. Light scattering of the lenses varies with latency time after exposure. A dose of 5 kJm(-2) UVR-B-300 nm induces light scattering in C57 mice lenses. The increase has a transient peak at 2 days after exposure. The variation of light scattering among days 1, 2, 4, and 8 indicates a dynamic change of scattering characteristics in the mouse lens following unilateral in vivo exposure to 5 kJm(-2) UVR-B-300 nm.
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| 8. |
- Tessem, May-Britt, et al.
(författare)
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Biological response in various compartments of the rat lens after in vivo exposure to UVR-B analyzed by HR-MAS 1H NMR spectroscopy
- 2006
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Ingår i: Investigative Ophthalmology and Visual Science. - : Association for Research in Vision and Ophthalmology (ARVO). - 0146-0404 .- 1552-5783. ; 47:12, s. 5404-5411
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: The purpose of the present study was to investigate metabolic changes in different compartments of the rat lens (anterior, nuclear, posterior, and equatorial) after exposure to an acute double threshold dose of ultraviolet-B radiation (UVR-B) by using high-resolution magic angle spinning (HR-MAS) (1)H nuclear magnetic resonance (NMR) spectroscopy and pattern recognition (PR) METHODS: methods. One eye in each of 28 6-week-old female albino Sprague-Dawley rats was exposed to in vivo 7.5 kJ/m2 UVR-B for 15 minutes. The contralateral eye was left unexposed. One week after irradiation, all rats were killed, and both lenses were isolated. Each lens was cored by a trephine, and the cylinder was sliced into three portions (anterior, nuclear, and posterior). The lens material that remained after the coring process was analyzed as the equatorial region. Analysis of lens metabolism was performed by HR-MAS 1H NMR spectroscopy (14.1 T; Avance DRX600; Bruker BioSpin GmbH, Rheinstetten, Germany), and the metabolic profiles were statistically analyzed by the PR method of principal component analysis (PCA). RESULTS: Metabolic differences were detected among the compartments in the lens, both in samples from the contralateral nonexposed lenses and in samples from lenses exposed to in vivo UVR-B. In the rat lens, exposure to UVR-B caused changes in GSH, phosphocholine, myo-inositol, succinate, formate, and adenosine triphosphate (ATP)/adenosine diphosphate (ADP) and in levels of the amino acids phenylalanine, taurine, hypo-taurine, tyrosine, alanine, valine, isoleucine, and glutamate, that varied among lens compartments. CONCLUSIONS: HR-MAS 1H NMR spectroscopy, combined with PR methods (PCA), is effective for analysis of separate parts of the intact rat lens. To understand the biochemistry of the lens, it is important to divide the lens into sections, representing functionally and anatomically distinct compartments.
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| 9. |
- Wang, Jing, et al.
(författare)
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Dose-response relationship for alpha-tocopherol prevention of ultraviolet radiation induced cataract in rat
- 2011
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Ingår i: Experimental Eye Research. - : Elsevier BV. - 0014-4835 .- 1096-0007. ; 93:1, s. 91-97
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this study is to establish the dose response relationship for alpha-tocopherol protection of ultraviolet radiation (UVR) induced cataract in the rat. Four groups of 20 six-week-old albino Sprague Dawley rats received 5, 25, 50, and 100 IU/day alpha-tocopherol, whilst another group of 20 rats without any alpha-tocopherol feeding was the control group. After 4 weeks of feeding, each rat was unilaterally exposed to 8 kJ/m(2) UVR-300 nm for 15 min. At 1 week after exposure, the rats were sacrificed and lens light scattering was measured quantitatively. Lens total reduced (GSH) and oxidized (GSSG) glutathione; glutathione reductase (GR) and peroxidase (GPx) were determined spectrophotometrically. The UVR-exposed lenses in the alpha-tocopherol fed groups developed superficial cataract, whereas lenses in the control group developed cortical and equatorial opacities. Light scattering in lenses from the alpha-tocopherol-supplemented rats was lower than in lenses from the control group. The difference of light scattering between the exposed and contralateral non-exposed lens decreased with increasing doses of alpha-tocopherol to an asymptote level. UVR-exposure caused a significant depletion of lens GSH in rats without or at low alpha-tocopherol supplementation. The depletion of GSH became less with higher alpha-tocopherol supplementation. There was no detectable difference in lens GSSG, GR or GPx at any level of alpha-tocopherol supplementation. Orally administered alpha-tocopherol dose dependently protects against UVR-induced cataract. The protection is associated with an alpha-tocopherol dose-dependent GSH depletion secondary to UVR exposure. UVR-induced light scattering only occurs if the GSH depletion exceeds a threshold.
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| 10. |
- Wang, Jing, et al.
(författare)
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Evolution of light scattering and redox balance in the rat lens after in vivo exposure to close-to-threshold dose ultraviolet radiation
- 2010
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Ingår i: Acta Ophthalmologica. - : Wiley. - 1755-3768 .- 1755-375X. ; 88:7, s. 779-785
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To investigate the evolution of cataract development and glutathione redox balance in the rat lens after in vivo close-to-threshold dose exposure to ultraviolet radiation (UVR) around 300 nm. Methods: Three groups of 10 Sprague-Dawley rats were unilaterally exposed to 8 kJ/m(2) UVR-300 nm for 15 min, and a fourth group of 10 rats was kept without UVR exposure as nonexposed control animals. The exposed animals were killed at 1, 3 and 7 days after exposure. Both lenses from all animals were extracted and photographed and the intensity of forward light scattering was measured quantitatively. Thereafter, the lenses were homogenized. The concentration of reduced glutathione (GSH) and oxidized glutathione (GSSG), and the activity of glutathione reductase (GR) and glutathione peroxidase (GPx), respectively, were determined spectrophotometrically. The mean paired differences between exposed and nonexposed lenses were used as primary data in the statistical analyses. Results: All exposed lenses developed cataract. Lens light scattering increased throughout the 7 days after UVR exposure. GSH concentration and GPx rate transiently increased at 1 day after exposure and then decreased throughout follow-up, with GSH concentration having a negative balance at the end. GSSG concentration and GR activity did not change after UVR exposure. Conclusion: In vivo close-to-threshold UVR exposure induces a gradual increase in rat lens opacification/cataract development and time dependently alters the redox balance in the lens.
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