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1
Wang, Kai. "Involvement of O-glcnacylation in lens development and cataract formation." Thesis, Birmingham, Ala. : University of Alabama at Birmingham, 2008. https://www.mhsl.uab.edu/dt/2010r/wang.pdf.
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Kumar, Bharat. "The Mechanobiology of the Crystalline Lens." The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1587649113548924.
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Jones, Catherine Elizabeth. "Studies of the crystalline lens using magnetic resonance imaging." Queensland University of Technology, 2004. http://eprints.qut.edu.au/15950/.
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The eye lens grows continuously throughout life and changes its shape as the eye changes focus from a distant to a near object (the process of accommodation). These changes are complex because they may affect not only the shape of the lens, but also its refractive index distribution. To date there has been no satisfactory technique for directly and non-invasively measuring these changes. In this study the refractive index distribution through the isolated lens was measured non-invasively using a novel MRI technique. The dependence of the refractive index value of lens tissue on its transverse relaxation rate (R2) was determined empirically from measurements on lens homogenate samples. Using a multi-spin-echo imaging sequence, data were acquired for constructing R2 maps of a central slice through the isolated lens. These R2 maps were transformed to refractive index maps using the empirically determined dependence of refractive index on R2. Using a standard algorithm for ray tracing through gradient index media, the propagation of light rays through the index map were simulated. The optical properties of the lens, such as focal length, were then measured. The technique was validated by also directly measuring the focal length of each lens using laser ray tracing. The subtle changes in refractive index distribution that are responsible for the dramatic change in the optical properties of the isolated lens with age, were observed for the first time. The decrease in surface power of the isolated lens with age accounted only partially for the decrease in total lens power with age, the remainder resulting from a reduction in the gradient of refractive index (GRIN) power. It is likely that this reduction in GFUN power is the mechanism by which the eye maintains emmetropia (good distant vision) with age despite the increasing curvature of its surfaces. The reduction in the GRIN power of the lens was found to be mainly due to a flattening of the refractive index profile in the central region of the lens, accompanied by steepening of the profile near the edge of the lens. In agreement with a previous MRI study of the isolated human eye lens, this study found a decrease in the refractive index of the nucleus with age. However the age related change in this study was not as large and not found to be statistically significant. The results demonstrate that existing simple models for the optics of the eye lens are inadequate to accurately describe its properties. Several more sophisticated models were considered in an attempt to describe better the age-dependent changes that occur in both the power of the lens and its longitudinal aberration. Mathematical modelling was also used to simulate the accommodative process and investigate possible changes in the index distribution of the lens that may occur with accommodation. A preliminary in vivo study was performed aimed at observing the change in the refractive index distribution of the eye lens with age and accommodation. These results demonstrated the feasibility of the technique for in vivo applications and showed that within experimental error there is little change in the central refractive index of the lens with age. However the resolution achievable with standard clinical imaging sequences and signal detection hardware was not optimal for in vivo refractive index mapping of changes in the human eye lens with accommodation. Finally therefore, methods for refining the technique for in vivo applications are discussed which may make it possible to directly and simultaneously measure both the shape and refractive index distribution of the lens with age and accommodation.
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Wilson, Cynthia Nicole. "A Fully Customizable Anatomically Correct Model of the Crystalline Lens." Thèse, Université d'Ottawa / University of Ottawa, 2011. http://hdl.handle.net/10393/20130.
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The human eye is a complex optical system comprised of many components. The crystalline lens, an optical component with a gradient index (GRIN), is perhaps the least understood as it is situated inside the eye and as a result is difficult to characterize. Its complex nonlinear structure is not easily measured and consequently not easily modeled. Presently several models of the GRIN structure exist describing the average performance of crystalline lenses. These models, however, do not accurately describe the performance of crystalline lenses on an individual basis and a more accurate individual eye model based on anatomical parameters is needed. This thesis proposes an anatomically correct, individually customizable crystalline lens model. This is an important tool and is needed both for research on the optical properties of human eyes and to diagnose and plan the treatment of optically based visual problems, such as refractive surgery planning. The lens model consisted of an interior GRIN with a constant refractive index core. The anterior and posterior surface was described by conic sections. To realize this eye model, the optical and biometric properties of mammalian lenses were measured and the correlation relationships between these measurements were used to simplify the model down to one fitting parameter which controls the shape of the GRIN. Using this data, an anatomically correct individualizable model of the lens was successfully realized with varying parameters unique to each lens. Using this customizable lens model, customizable human eye models based on measurements of the entire human eye can be realized.
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Hott, John Lester. "Photochemical alterations of ocular lens proteins." Diss., Georgia Institute of Technology, 1991. http://hdl.handle.net/1853/30087.
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O'Leary, Christine Marie. "Expression of the Ets family in the lens." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file 2.78 Mb., 100 p, 2005. http://wwwlib.umi.com/dissertations/fullcit/1428194.
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Rabie, E. P. "Biometry of the crystalline lens during accommodation." Thesis, University of Manchester, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.378316.
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Chen, Wen-Lung. "Raman spectroscopic/imaging studies of eye lenses and lens proteins." Diss., Georgia Institute of Technology, 1991. http://hdl.handle.net/1853/30431.
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Walker, Marlon LeBrone. "Light scattering and light transmission studies of uv-induced protein crosslinking in separated lens crystallins and whole lenses." Diss., Georgia Institute of Technology, 1988. http://hdl.handle.net/1853/26245.
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Walker, Heather Mhairi. "Investigating the role of the lens in the growth and development of the vertebrate eye." Thesis, University of Aberdeen, 2014. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=225773.
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The eye forms through complex tissue interactions, and it still only partly understood. The developing vertebrate lens however, is crucial for coordinating eye development and eye growth, through releasing signals to surrounding eye structures. It is thought that the lens controls the growth of the eye through the production of the vitreous- the jelly-like substance that fills the main cavity of the eye and maintains the eye in its correct shape. Many components of the vitreous are produced by a region of the peripheral retina known as the ciliary body, and so it is believed that the lens controls eye growth through controlling the development of the ciliary body and thus, indirectly, the vitreous. This project addresses this concept. I have identified a previously unknown functional link between the lens and Vitamin A metabolism. The lens is important for maintaining retinoic acid production within the developing chick eye through controlling the expression of RDH10 in the presumptive ciliary body. RDH10 is important for the first step in retinoic acid synthesis, the conversion of Vitamin A into retinal, which is then converted into retinoic acid. The loss of RDH10 within the presumptive ciliary body is associated with a reduction in expression of other genes known to be involved in ciliary body development, BMP7, WNT2B and OTX1 along with a reduction in the growth of the eye. The reduction in retinoic acid production within the eye as a result of lens removal, in turn affects the synthesis of Collagen IX from the ciliary body, a major component of the vitreous. The data suggests that the lens controls retinoic acid production within the eye, through maintaining gene expression in the developing ciliary body. Retinoic acid signalling controls the synthesis of components of the vitreous, such as Collagen IX. The proper accumulation of the vitreous within the eye is crucial for the correct growth of the chick eye.
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Wang, Zaiqi. "Lens calcium homeostasis and selenite cataract." Diss., This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-05042006-164509/.
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Banks, Eric A. "Connexin 45.6 in lens development : a dissertation /." San Antonio : UTHSC, 2007. http://proquest.umi.com/pqdweb?did=1400957401&sid=1&Fmt=2&clientId=70986&RQT=309&VName=PQD.
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Li, Dongyun. "The effect of UV-laser radiation on lenses and lens proteins." Thesis, Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/27271.
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Hook, Darren W. A. "Protection of enzymes by the molecular chaperone #alpha#-Crystalline." Thesis, University of Oxford, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.300133.
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Taube, Jennifer Remington. "Regulation of beta-B1 crystallin expression." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file 8.90 Mb., 227 p, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:3200530.
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Neveling, Lauren Leigh. "Probing the kinetics of unfolding and aggregation of human gamma-D crystallin at low PH using Fourier transform infrared spectroscopy /." Connect to online version, 2007. http://ada.mtholyoke.edu/setr/websrc/pdfs/www/2007/212.pdf.
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Hawse, John R. "Identification and functional characterization of cataract-specific gene expression changes reveals important pathways for human lens maintenance, aging and disease." Morgantown, W. Va. : [West Virginia University Libraries], 2004. https://etd.wvu.edu/etd/controller.jsp?moduleName=documentdata&jsp%5FetdId=3365.
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Thesis (Ph. D.)--West Virginia University, 2004.Title from document title page. Document formatted into pages; contains x, 201 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 185-201).
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Bergbauer, Katrina L. "Laser raman spectroscopic studies of ocular lens aging and cataractogenesis." Diss., Georgia Institute of Technology, 1991. http://hdl.handle.net/1853/30031.
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Schultz, Kristin E. "Accommodative microfluctuations, crystalline lens tension, ciliary body thickness, and refractive error in children." Columbus, Ohio : Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1240445960.
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Grant, Edwin Arthur. "Immuno-Labeling of Yes-associated Protein in the Crystalline Lens." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1460499774.
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Travers, Margaret J. "Structural correlates of shape change in the primate crystalline lens." Thesis, City University London, 1990. http://openaccess.city.ac.uk/7669/.
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Cytological changes associated with accommodation in macaques and man were investigated using light and scanning electron microscopy to examine lenticular fibre modification and the role of the lens capsule. Accommodation was simulated monocularly in one animal with local administration of 1/4% phospholine iodide and by dislocation in another followed by fixation by perfusion. Three types of junctional structures were observed: angle processes were found at all depths, ball and sockets in outer lens zones, and tongue and grooves in the deeper lens. Interfaces lacking junctional structures were not present and the concept of sliding between fibre layers to permit curvature changes was rejected. The hypothesis of intracellular redistribution of cytoplasm within lens fibres was tested, by comparing fibre cross sectional area throughout the posterior half of accommodated and unaccommodated lenses. In one animal evidence for cytoplasmic flow was found throughout the lens but was greatest in the nucleus. In the other, showing less curvature difference, evidence was restricted the nucleu and superficial cortex. The thin superficial cortex is probably of little significance in effecting shape change. Consequently the results support the notion of greater nuclear than cortical action in accommodative shape changes. The fibres of the intermediate and deep cortex are remarkably thin and indented and are arguably less conducive to cytoplasmic flow. Lens capsule thickness was measured in 23 monkey and 11 human lenses in situ and detached, giving similar results. Profiles were recorded of unfixed monkey lenses with and without capsules. An annular zone of flattening, nearly coincident with maximum capsular thickness, giving the classical 'lenticonus" form, reduced on decapsulation. The young human and monkey capsule thickness variation was consistent with classical rather than more recent data thinnest at the posterior pole and thickest near, not at the equator. The results demonstrate a role for capsular shaping of the accommodated lens (with or without local moulding), effected by cytoplasmic flow most marked in the nucleus.
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Beck, Claire. "The characterisation of fluorescent proteins in the diabetic crystalline lens." Thesis, University of Warwick, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.404870.
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Knight, Grady C. "The molecular chaperone α-crystallin protects proteins from UV-induced aggregation." Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/30486.
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Barron, Brent Christian. "Characterization of normal aging and cataractous processes in the eye lens by laser raman spectroscopy." Diss., Georgia Institute of Technology, 1988. http://hdl.handle.net/1853/30052.
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Lehman, Bret M. "Validation of Optical Coherence Tomography-Based Crystalline Lens Thickness Measurements in Children." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1242248244.
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Koivula, Annemari. "Long-term results of phakic refractive lenses for correction of myopia and hyperopia /." Stockholm, 2007. http://diss.kib.ki.se/2007/978-91-7357-424-2/.
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Tuten, William Scott. "Anterior Segment Optical Coherence Tomography-Based Phakometry Measurements in Children." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1243629782.
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Nisa, Georgette. "The prevalenceof anterior segment and crystalline lens changes in a Nicaraguan population." Thesis, Linnéuniversitetet, Institutionen för medicin och optometri (MEO), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-54213.
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Abstract Aim: The purpose of this study was to find the prevalence of different ocular changes in the anterior segment of the eye and changes in the crystalline lens among Nicaraguan population. Method: The study was done during a journey to Nicaragua with the organization VFA and Synoptik that lasted for two weeks in March/April. There were a total of 134 participants with 71 females and 63 males. The average age of the study participants was 50 (±20) years and the age ranged from 7 to 97 years. The total sample size was collected in the three towns that we visited during the journey: Ticuantepe, Léon and Estéli. The changes were evaluated by direct ophthalmoscopy. Conjunctiva was examined by asking the patients to look into different gaze directions. Cornea and crystalline lens was examined by asking the patient to look directly at the ophthalmoscope. Results: 31% out of the participants enrolled in this study were healthy with no visible ocular changes. The remaining 69% had ocular changes with majority of them having either cataract, pterygium or pinguecula. The prevalence of cataract was 24%, pterygium 20%, pinguecula 10%. There were other minor ocular changes such as red eye in 4%, arcus senilis in 4%, ptosis in 1%, and aphakia in 1% seen in these participants. Conclusion: The UV related changes had the highest prevalence. This study like previous studies have shown that cataract was most prevalent ocular change in this population.
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Eckes, Melissa. "Shroom3 Localization and Apical Constriction during the Development of the Crystalline Lens in Mouse Embryos." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1492728223255337.
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Nankivil, Derek. "A Second Generation Ex-Vivo Accommodation Simulator: Design and Calibration." Scholarly Repository, 2008. http://scholarlyrepository.miami.edu/oa_theses/161.
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Presbyopia is the progressive decrease in accommodative ability with age, and it implies a major loss of visual function. Presbyopia is the only condition of the eye which affects everyone who lives beyond 50 years of age. As part of a joint effort, the Ophthalmic Biophysics Center at the Bascom Palmer Eye Institute and the Vision Cooperative Research Centre at the University of New South Wales, developed two different ex-vivo accommodation simulators (EVAS) to examine the mechanisms of accommodation and presbyopia, and to test and validate new ophthalmic surgical procedures such as lens refilling. The purpose of this thesis is to mechanically and optically calibrate the second generation instrument (EVASII), and to compare it to the first generation design (EVASI). To validate the optical measurements of EVASII, an optical calibration has been performed, yielding a lens power measurement system with a mean accuracy of ±0.56D. To enhance the optical capabilities and tissue dissection options, the mechanics of mounting the tissue has been improved by using magnetic mounts, and the mechanical calibration of EVASII, yielded a force measurement system with a mean uncertainty of ±0.81g Also, a comparison of EVASII and EVASI has been performed, showing that the results of the two systems are significantly different; however, both systems successfully simulate accommodation. Thus, general trends concerning efficacy and optimization of surgical procedures as well as age related accommodative changes can be compared for each individual system.
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Li, Yi. "Cell proliferation as a biomarker of aging and effect of caloric restriction in mouse lens /." Thesis, Connect to this title online; UW restricted, 1997. http://hdl.handle.net/1773/6328.
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Borja, David. "Dynamic Optical Model of the Primate Crystalline Lens and Implications for the Restoration of Accommodation." Scholarly Repository, 2008. http://scholarlyrepository.miami.edu/oa_dissertations/355.
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The human crystalline lens is a complex, inhomogeneous and dynamic optical element which enables the eye to adjust focus in a process known as accommodation. Age related changes in the optical and mechanical properties of the lens cause a loss in accommodative ability leading to a condition known as presbyopia. Several experimental surgical techniques are under development for the correction of presbyopia. The goal of this dissertation is to better understand the relationship between the crystalline lens shape, its non-uniform refractive index gradient and its optical power and their changes with age and accommodation. In this study direct lens power and shape measurements were acquired on isolated lenses, and on lenses mounted in a lens stretching system designed to simulate accommodation. Several lens shape and power measurement techniques were developed for this study including a Scheimpflug camera system optimized for imaging the crystalline lens. Direct measurements of lens shape and power were used to develop an age-dependent optical-mechanical model of the lens during accommodation. The study shows that the normal growth of the lens is a major contributor to the progressive loss of accommodation amplitude, independent of changes in the elastic properties of the lens. These findings suggest that accommodation can be restored by refilling the lens with a material having a uniform refractive index.
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Parker, Nicole Renee. "The role of kynurenine and UV light in lens protein modification." Access electronically, 2005. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20060720.111305/index.html.
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Thesis (Ph.D.)--University of Wollongong, 2005.Typescript. EMBARGOED - This thesis is subject to a 12 month embargo (07/03/06 to 07/03/07) and may only be viewed and copied with the permission of the author. For further information please Contact the Archivist. Includes bibliographical references: leaf 236-266.
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Cheng, Man-hei. "The novel mouse [gamma]A-crystallin mutation leads to misfolded protein aggregate and cataract." Click to view the E-thesis via HKUTO, 2009. http://sunzi.lib.hku.hk/hkuto/record/B43572108.
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Michael, Ralph. "Development and repair of cataract induced by ultraviolet radiation /." Basel ; Stockholm : Karger, 2000. http://diss.kib.ki.se/2000/3-8055-7044-9/.
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Chiu, Kin. "Immune modulation on retinal ganglion cell survival in experimental glaucoma." Click to view the E-thesis via HKUTO, 2008. http://sunzi.lib.hku.hk/hkuto/record/B40987693.
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Mizdrak, Jasminka. "Human lens chemistry: UV filters and age-related nuclear cataract." Australia : Macquarie University, 2007. http://hdl.handle.net/1959.14/16855.
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"A thesis submitted in partial fulfillment of the requirements for the award of the degree of Doctor of Philosophy".Thesis (PhD) -- Macquarie University, Division of Environmental and Life Sciences, Dept. of Chemistry and Biomolecular Sciences, 2007.
Bibliography: p. 243-277.
Introduction -- A convenient synthesis of 30HKG -- Facile synthesis of the UV filter compounds 30HKyn and AHBG -- Synthesis, identification and quantification of novel human lens metabolites -- Modification of bovine lens protein with UV filters and related metabolites -- Effect of UV light on UV filter-treated lens proteins -- Conclusions and future directions.
The kynurenine-based UV filters are unstable under physiological conditions and undergo side chain deamination, resulting in α,β-unsaturated carbonyl compounds. These compounds can react with free or protein bound nucleophiles in the lens via Michael addition. The key sites of the UV filters kynurenine (Kyn) and 3-hydroxykynurenine (3OHKyn) modification in human lenses include cysteine (Cys), and to a lesser extent, lysine (Lys) and histidine (His) residues. Recent in vivo studies have revealed that 3-hydroxykynurenine-O-β-D-glucoside (3OHKG) binds to Cys residues of lens crystallins in older normal human lenses. As a result of this binding, human lens proteins become progressively modified by UV filters in an age-dependent manner, contributing to changes that occur with the development of age-related nuclear (ARN) cataract. Upon exposure to UV light, free UV filters are poor photosensitisers, however the role of protein-bound species is less clear. It has been recently demonstrated that Kyn, when bound to lens proteins, becomes more susceptible to photo-oxidation by UV light. Therefore, the investigation of 3OHKG binding to lens proteins, and the effect of UV light on proteins modified with 3OHKG and 3OHKyn, were major aims of this study. As a result of the role of these compounds as UV filters and their possible involvement in ARN cataract formation, it is crucial to understand the nature, concentration and modes of action of the UV filters and their metabolites present in the human lenses. Therefore, an additional aim was to investigate human lenses for the presence of novel kynurenine-based human lens metabolites and examine their reactivity.--As 3OHKG is not commercially available, to conduct protein binding studies, an initial aim of this study was to synthesise 3OHKG (Chapter 2). Through the expansion and optimisation of a literature procedure, 3OHKG was successfully synthesised using commercially available and inexpensive reagents, and applying green chemistry principles, where toxic and corrosive reagents were replaced with benign reagents and solvent-free and microwave chemistry was used. A detailed investigation of different reaction conditions was also conducted, resulting in either the improvement of reaction yields or reaction time compared to the literature method. Applying the same synthetic strategy, and using key precursors from the synthesis of 3OHKG, the UV filters 3OHKyn and 4-(2-amino-3-hydroxyphenyl)-4-oxobutanoic acid-O-β-D-glucoside (AHBG), were also successfully synthesised (Chapter 3).
Chapter 4 describes the investigation of both normal and cataractous human lenses in an attempt to identify novel human lens metabolites derived from deaminated Kyn and 3OHKyn (Chapter 4, Part A). Initially, 4-(2-aminophenyl)-4-oxobutanoic acid (AHA), glutathionyl-kynurenine (GSH-Kyn), kynurenine yellow (Kyn yellow), 4-(2-amino-3-hydroxyphenyl)-4-oxobutanoic acid (AHB), glutathionyl-3-hydroxykynurenine (GSH-3OHKyn) and 3-hydroxykynurenine yellow (3OHKyn yellow) were synthesised and human lenses were examined for their presence. AHA and AHB were synthesised from similar precursors to those used in the synthesis of 3OHKG, while the GSH adducts and yellow compounds were synthesised from Kyn and 3OHKyn via base induced deamination. Following isolation and structural elucidation, AHA, AHB and GSH-Kyn were confirmed as novel human lens metabolites. They were quantified in low pmol/mg lens (dry mass) levels in normal and cataractous lenses of all ages, while GSH-3OHKyn, Kyn yellow and 3OHKyn yellow were not detected. In contrast to AHA, the lens metabolites AHB, GSH-Kyn and GSH-3OHKyn were found to be unstable at physiological pH. The spectral properties of these compounds suggest that they may act as UV filters. --Chapter 4 (Part B) also describes the identification and characterisation of a novel human lens UV filter, cysteinyl-3-hydroxykynurenine -O-β-D-glucoside (Cys-3OHKG). An authentic standard was synthesised via Michael addition of cysteine to deaminated 3OHKG. Cys-3OHKG was detected in low pmol/mg lens (dry mass) levels in normal lenses only after the 5th decade of life and was absent in cataractous lenses. Cys-3OHKG showed rapid decomposition at physiological pH.
Chapter 5 describes the identification and quantification of amino acids involved in covalent binding of 3OHKG to lens proteins. Model studies with bovine lens proteins and 3OHKG at pH 7.2 and 9.5 were undertaken. The amino acid adducts were identified via total synthesis and spectral analysis, and subsequently quantified upon acid hydrolysis of the modified lens proteins. Under both pH conditions, 3OHKG was found to react with lens proteins predominantly via Cys residues with low levels of binding also detected at Lys residues. Comparative studies with Kyn (pH 9.5) and 3OHKyn (pH 7.2 and 9.5) resulted in modified lens proteins at Cys residues, with only minor modification at Lys residues at pH 9.5. The extent of modification was found to be significantly higher at pH 9.5 in all cases. His adducts were not identified. 3OHKG-, Kyn- and 3OHKyn-modified lens proteins were found to be coloured and fluorescent, resembling those of aged and ARN cataractous lenses. In contrast, AHB and AHA, which can not form α,β-unsaturated carbonyl compounds, resulted in non-covalent modification of lens proteins. AHB may contribute to lens colouration and fluorescence as further reactions of this material yielded species that have similar characteristics to those identified from 3OHKyn modification. These species are postulated to arise via auto-oxidation of the o-aminophenol moiety present in both 3OHKyn and AHB.--In Chapter 6, the potential roles of 3OHKG and 3OHKyn, and the related species AHA and AHB, in generating reactive oxygen species and protein damage following illumination with UV light was examined. The UV filter compounds were examined in both their free and protein-bound forms. Kyn-modified proteins were used as a positive control. Exposure of these compounds to UV light (λ 305-385 nm) has been shown to generate H2O2 and protein-bound peroxides in a time-dependent manner, with shorter wavelengths generating more peroxides. The yields of peroxides were observed to be highly dependent on the nature of the UV filter compound and whether these species were free or protein bound, with much higher levels being detected with the bound species. Thus, protein-bound 3OHKyn yielded higher levels of peroxide than 3OHKG, with these levels, in turn, higher than for the free UV filter compounds. AHB-treated lens proteins resulted in formation of low but statistically significant levels of peroxides, while AHA-treated lens proteins resulted in insignificant peroxide formation. The consequences of these photochemical reactions have been examined by quantifying protein-bound tyrosine oxidation products (3,4-dihydroxyphenylalanine [DOPA], di-tyrosine [di-Tyr]) and protein cross-linking. 3OHKG-modified proteins gave elevated levels of di-Tyr, but not DOPA, whereas 3OHKyn-modified protein gave the inverse. DOPA formation was observed to be independent of illumination and most likely arose via o-aminophenol auto-oxidation. AHB- and AHA-treated lens proteins resulted in statistically insignificant di-Tyr formation, while a light independent increase in DOPA was observed for both samples. Both reducible (disulfide) and non-reducible cross-links were detected in modified proteins following illumination. These linkages were present at lower levels in modified, but non-illuminated proteins, and absent from unmodified protein samples.
This work has provided an optimised synthetic procedure for 3OHKG and other lens metabolites (Chapters 2 and 3). Four novel lens metabolites have been identified and quantified in normal and cataractous human lenses (Chapter 4). Subsequent experiments, described in Chapter 5, identified the major covalent binding sites of 3OHKG to lens proteins, while AHA and AHB showed non-covalent binding. Further work described in Chapter 6 showed that protein-bound 3OHKG, Kyn and 3OHKyn were better photosensitisers of oxidative damage than in their unbound state. Together, this research has provided strong evidence that post-translational modifications of lens proteins by kynurenine-based metabolites and their interaction with UV light appear, at least in part, responsible for the age-dependent colouration of human lenses and an elevated level of oxidative stress in older lenses. These processes may contribute to the progression of ARN cataract.
Mode of access: World Wide Web.
xxxix, 308 p. ill. (some col.)
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Ruggeri, Marco. "Extended Depth Optical Coherence Tomography for Anterior Segment and Accommodation Imaging in Real-Time." Scholarly Repository, 2011. http://scholarlyrepository.miami.edu/oa_dissertations/686.
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The changes in the human crystalline lens shape and its internal structure during accommodation and with aging are a fundamental component of the dynamic mechanism of accommodation and presbyopia, the loss of near vision with age. A better understanding of the crystalline lens changes during accommodation will help in developing new treatments to correct for presbyopia. The goal of this dissertation is to design and develop an imaging system to study the dynamic changes in lens shape during accommodative response. An imaging system based on spectral domain optical coherence tomography (SD-OCT) was developed with long axial range, high axial and lateral resolution and high speed for in vivo imaging the anterior segment along its entire length at video-rate. A slit-lamp mounted optical delivery scanning device for the extended depth SD-OCT system was developed. The delivery system was combined with a custom made unit that provides accommodation and disaccommodation step stimuli. A method to correct for the distortions of the OCT images was also developed that provides corrected two dimensional biometric data at different accommodative states.
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Chandler, Heather Lynn. "Epithelial-mesenchymal transition in the anterior segment of the eye." Columbus, Ohio : Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1154533588.
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Wejde, Gisela. "Posterior capsule opacification and postoperative endophthalmitis following cataract surgery : predictive and protective factors /." Stockholm : Karolinska institutet, 2005. http://diss.kib.ki.se/2005/91-7140-291-8/.
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Cheng, Man-hei, and 鄭文熙. "The novel mouse [gamma]A-crystallin mutation leads to misfolded protein aggregate and cataract." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2009. http://hub.hku.hk/bib/B43572108.
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Meyer, David. "A critical appraisal of the etiology of adult human lenticular opacification and an investigation into the role of metabolic factors in its pathogenesis." Thesis, Stellenbosch : Stellenbosch University, 2001. http://hdl.handle.net/10019.1/52069.
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Thesis (PhD)--Stellenbosch University, 2001ENGLISH ABSTRACT: The eye is that biological instrument which conveys the light of the external world into the inner world of the mind, wherein we receive the miraculous gift of vision. So precious is this gift, that Science must search for ways to keep this portal clear for the flow of light. Indeed, Science is called upon to “make war upon the bloody tyrant, Time.” (Shakespeare W. Sonnet No. 16). For, in the course of ageing, the lens grows cloudy and cataractous. In this battle between Science and Time, we are fortunate to live in an era in which Science is uncovering the molecular basis for the various obstacles to vision. The question arises, whether or not, the ruinous hand of time can be stayed. Due to unrelenting, progressive lens opacification, most of the elderly are destined to be subjected to loss of vision and with passage of time, even blindness. Globally the cataract surgery rate is inadequate to keep pace with the ever growing demand on financial and human resources created by the cataract problem. An immense challenge therefore is directed to primary eye care: “Can cataract be prevented or can its onset at least be postponed?” This laudable ultimate aim can only be achieved once the etiology of cataractogenesis is well understood. This dissertation seeks to examine two previously unrecognized etiological aspects that, if correctly understood and managed, have the potential to achieve preventive ophthalmological goals that may indeed help to stay the ‘ruinous hand of time’. The first aspect deals with the role of lipids and was examined using a study group of dyslipidemic subjects. The first part of the study concluded that dyslipidemic patients develop cortical lens opacities more frequently and at an earlier age than the normal population, and that cortical lens opacities should be regarded as one of the most reliable clinical signs of dyslipidemia. Furthermore, an extremely strong correlation was found to exist between low HDL Cholesterol levels and the development of opacities. Below a HDL-Cholesterol level of 1,5mmol/l, subjects had more than seven-fold higher risk of falling in the lens opacity subgroup than those with HDLCholesterol levels above 1,5mmol/l. An equally strong correlation was demonstrated between high (>5) LDLHDL ratios and the development of lens opacities. Subjects with a LDL:HDL-C ratio below 5 possessed a 2.35 times greater risk of having lenticular opacities than the group with a LDL:HDL-C ratio greater than 5. The prevention or retardation of dyslipidemia associated lens opacities is therefore possible, provided patients with a genetic predisposition are detected early and their blood lipids managed adequately. The second aspect deals with the relationship between age related cataracts and the acetylation status of the individual. This study compellingly submits that the slow acetylator pheno- and genotype may be regarded as a genetic indicator of risk for age related cataract. The ability accurately to classify a patient genotypically and phenotypically, may henceforth be useful in health counseling since, if an individual is identified as being a slow acetylator, additional preventative and precautionary measures may be taken, i.e. the prevention of UVexposure to the eye and caution with the ingestion of xenobiotics like caffeine, commercial dyes, food preservatives, and drugs. Furthermore, such a finding should be taken into account in the long term therapeutic management of glaucoma, with special regard to carbonic anhydrase inhibitors which are sulphonamide-related drugs and totally dependent on the N-acetyltransferase pathway for metabolism. These drugs may accumulate in the slow acetylator over time and exert toxic effects intra-ocularly, conceivably including cataractogenesis. The search for genetic and metabolic mechanisms that may contribute to human cataractogenesis should be pursued with great enthusiasm. This endeavour may help Science to achieve its primary objective, ablate the effects of Time and really aid in preventing cataracts in man.
AFRIKAANSE OPSOMMING: Die wondergawe van visie word vir ons moontlik gemaak deur die oog wat as biologiese instrument die lig van die buitewereld inlaat na die binnewereld van die brein. So kosbaar is hierdie gawe dat die Wetenskap deurgaans moet poog om die poort oop te hou. Inteendeel, die Wetenskap word gemaan deur Shakespeare in sy Sonnet nommer 16 om “oorlog te maak teen die bloeddorstige tiran, Tyd”. Soos ‘n mens ouer word, word die lens dof en ‘n katarak mag vorm. Ten spyte van hierdie stryd tussen ‘Wetenskap’ en ‘Tyd’ leef ons in die gelukkige era waarin die Wetenskap meer en meer leer van die verskeie obstruksies tot visie. Die vraag ontstaan of die rinnewerende hand van ‘Tyd’ gestuit sal kan word. Vanwee ongenaakbare, progressiewe lensvertroebeling is die meeste bejaardes bestem om aan visie verlies, en met verloop van tyd selfs blindheid, te ly. Die wereldwye katarakchirurgie tempo is nie voldoende om by te hou by die immergroeiende finansiele en mannekrag eise wat deur die katarak probleem gestel word nie. Daar word dus ‘n reuse uitdaging aan primere oogsorg gestel naamlik: “Kan katarakte nie eerder voorkom of die aanvang daarvan ten minste uitgestel word nie?” Hierdie prysenswaardige doelwit kan nie bereik word alvorens die etiologie van kataraktogenese goed verstaan word nie. Hierdie tesis ondersoek twee voorheen onerkende etiologiese aspekte wat, indien hulle korrek verstaan en hanteer word, beslis die potensiaal het om die gemelde voorkomende doelwitte te bereik en sekerlik te kan bydrae om die rinnewerende hand van Tyd te stuit. Die eerste aspek spreek die rol van lipiede aan deur te kyk na 'n studiegroep van dislipidemiese persone. Die eerste deel van die studie kom tot die gevolgtrekking dat dislipidemiese pasiente kortikale lens opasiteite meer dikwels en op ‘n vroeer ouderdom ontwikkel as die normale populasie en dat sulke opasiteite beskou moet word as een van die mees betroubare kliniese tekens van dislipidemie. Daar is ook ‘n baie sterk korrelasie gevind tussen lae HDL cholesterol vlakke en die voorkoms van opasiteite. Persone in die studie met ‘n HDL cholesterol vlak laer as 1,5mmol/l het ‘n sewe keer hoer kans gehad om in die lensopasiteit subgroep te val as die met ‘n HDL cholesterol vlak laer as 1,5mmol/l. ‘n Sterk korrelasie tussen ‘n hoe (>5) LDLHDL verhouding en die voorkoms van lens opasiteite is ook gevind. Persone met ‘n LDLHDL verhouding >5 het ‘n 2.35 maal groter risiko gehad om lensopasiteite te he as die met ‘n LDL:HDL verhouding van <5. Die voorkoming of vertraging van dislipiedemie geassosieerde lens opasiteite is dus moontlik, solank persone met ‘n genetiese geneigdheid daartoe vroeg ontdek en hulle bloedlipiede voldoende beheer word. Die tweede deel van die tesis handel oor die verhouding tussen ouderdoms verwante katarakte en die asetilasie status van die individu. Met oortuiging kom hierdie studie tot die gevolgtrekking dat die stadige asetilator fenoen genotipe as 'n genetiese merker vir ouderdoms verwante katarakte beskou moet word. Die vermoe om ‘n individu beide genotipies en fenotipies akkuraat te klassifiseer mag voorts bruikbaar wees in gesondheidsraadgewing. Indien ‘n individu geTdentifiseer is as ‘n stadige asetileerder, kan addisionele voorsorg maatreels getref word soos bv. die voorkoming van blootstelling van die oog aan UV lig sowel as omsigtigheid met die inname van xenobiotika soos kaffei'ene, kleurstowwe, voedsel preserveermiddels en geneesmiddels. Hierdie bevinding moet ook in berekening gebring word in die langtermyn terapeutiese hantering van gloukoom. Die koolsuuranhidrase inhibitore, dikwels gebruik in die behandeling van gloukoom, is sulfonamied-agtige middels en dus totaal afhanklik van die N-asetieltransferase pad vir hulle metabolisme. Hierdie middels kan ophoop in die stadige asetileerder en gegewe genoeg tyd, bes moontlik toksiese intra-okulere effekte tot gevolg he. Die soeke na genetiese en metaboliese meganismes wat mag bydra tot menslike kataraktogenese behoort nagestreef te word met groot entoesiasme. Hierdie strewe mag dalk net vir die 'Wetenskap' bystaan om sy primere mikpunt te bereik, die effek van ‘Tyd’ te neutraliseer en te help om katarakte werklik te voorkom.
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Meyer, Linda Maren. "Cataract from ultraviolet radiation in the mouse /." Stockholm, 2005. http://diss.kib.ki.se/2005/91-7140-583-6/.
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Chiu, Kin, and 趙健. "Immune modulation on retinal ganglion cell survival in experimental glaucoma." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2008. http://hub.hku.hk/bib/B40987693.
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Oriowo, Olanrewaju Matthew. "A study of ultraviolet radiation effects on porcine crystalline lens and development of a new assay methodology for UV cataractogenesis investigation." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0027/NQ51219.pdf.
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Zhao, Haotian. "Exploring the role of fibroblast growth factor (FGF) signaling in mouse lens fiber differentiation through tissue-specific disruption of FGF receptor gene family." Connect to this title online, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1072722841.
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Thesis (Ph. D.)--Ohio State University, 2004.Title from first page of PDF file. Document formatted into pages; contains xii, 203 p.; also includes graphics (some col.) Includes bibliographical references (p. 179-203). Available online via OhioLINK's ETD Center
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Dong, Xiuqin. "Safety limit estimation for cataract induced by ultraviolet radiation /." Stockholm, 2005. http://diss.kib.ki.se/2005/91-7140-451-1/.
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Sjödal, My. "Specification of the lens and olfactory placodes and dorsoventral patterning of the telencephalon /." Umeå : Univ, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-1347.
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D'Antin, Justin Christopher. "Lens capsule tissue culture for the investigation and prevention of posterior capsule opacification." Doctoral thesis, Universitat Autònoma de Barcelona, 2020. http://hdl.handle.net/10803/670465.
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Les cataractes són la principal causa de ceguesa al món i es deuen a una opacificació progressiva del cristal·lí. Encara que les cataractes siguin fàcils de tractar, en molts casos la mateixa cirurgia pot donar lloc a una segona pèrdua de la visió, coneguda com a opacificació de la càpsula posterior (OCP). La OCP es desenvolupa a causa d'una combinació de la proliferació, migració i transdiferenciació de les cèl·lules residuals que queden a la càpsula del cristal·lí després de la cirurgia de cataractes, el que resulta en una pèrdua progressiva de la visió.
Hi ha molts estudis sobre la prevenció de l'OCP, des d'ajustos de les tècniques i materials quirúrgics, fins a tractaments farmacològics. Actualment, l'opció més efectiva és evitar mecànicament que les cèl·lules envaeixin l'eix visual. Malgrat aquests avenços, l'OCP i segueix sent una complicació postquirúrgica que afecta molts pacients.
En aquesta tesi, hem utilitzat un model in vitro de teixit capsular per estudiar el desenvolupament i la possible prevenció d'OCP. En el nostre primer estudi, fem veure la progressió natural de l'OCP in vitro i posteriorment tractem de prevenir-la amb diferents substàncies. No obstant això, tot i utilitzar un tractament agressiu de peròxid d'hidrogen, es va desenvolupar OCP en la meitat dels casos. Això va destacar la impressionant resistència d'aquestes cèl·lules i la dificultat de prevenir el seu desenvolupament.
En el nostre segon estudi, mostres d'OCP que s'havien desenvolupat in vivo, van ser comparades amb les nostres mostres in vitro anteriors per comprendre millor el desenvolupament de l'OCP. Concloem que l'OCP es deu al procés fallit per part de les cèl·lules residuals de regenerar el cristal·lí.
Això ens va fer tornar a avaluar el nostre enfocament sobre la prevenció de l'OCP. En lloc d'estudiar diferents formes de prevenir el desenvolupament de l'OCP farmacològicament, ara pretendre estudiar si les cèl·lules poguessin regenerar un cristal·lí transparent. La idea de regenerar el cristal·lí no és nova, però només s'ha observat i estudiat en animals i nadons, mai en humans adults.
Amb aquest nou objectiu en ment, primer volíem estudiar si els casos avançats d'OCP desenvolupen de forma natural teixit transparent, tot i semblar opac quan s'observa clínicament. Per fer això, vam extraure mostres avançades d'OCP de teixit ocular de donants ex vivo i les seccionem gruixudament per analitzar-les sagitalmente. Observem que en la majoria dels casos una porció significativa del teixit intern era transparent. Això va donar suport encara més la nostra idea de la regeneració del cristal·lí com una possible opció de tractament futur.
Finalment, vam desenvolupar un nou model de cultiu in vitro que considerem que afavorís el desenvolupament de cèl·lules normals del cristal·lí en lloc de cèl·lules fibròtiques. Realitzem canvis en la preparació quirúrgica de les mostres per augmentar el nombre inicial de cèl·lules, reduir l'estrès cel·lular i millorar el contacte entre les càpsules anterior i posterior. No obstant això, no vam aconseguir la regeneració del cristal·lí, però disminuïm alguns factors relacionats amb l'OCP fibròtica. Això ressalta la complexitat d'aquest nou enfocament.
Aquesta tesi i la idea de la regeneració del cristal·lí com a tractament obren moltes noves vies d'estudi interessants i tenim tota la intenció de continuar per aquest nou camí.Las cataratas son la principal causa de ceguera en el mundo y se deben a una opacificación progresiva del cristalino. Aunque las cataratas sean fáciles de tratar, en muchos casos la misma cirugía puede dar lugar a una segunda pérdida de la visión, conocida como opacificación de la cápsula posterior (OCP). La OCP se desarrolla debido a una combinación de la proliferación, migración y transdiferenciación de las células residuales que quedan en la cápsula del cristalino tras la cirugía de cataratas, lo que resulta en una pérdida progresiva de la visión. Hay muchos estudios sobre la prevención de la OCP, desde ajustes de las técnicas y materiales quirúrgicos, hasta tratamientos farmacológicos. Actualmente, la opción más efectiva es evitar mecánicamente que las células invadan el eje visual. A pesar de estos avances, la OCP y sigue siendo una complicación postquirúrgica que afecta a muchos pacientes. En esta tesis, hemos utilizado un modelo in vitro de tejido capsular para estudiar el desarrollo y la posible prevención de OCP. En nuestro primer estudio, simulamos la progresión natural de la OCP in vitro y posteriormente tratamos de prevenirla con diferentes sustancias. Sin embargo, a pesar de utilizar un tratamiento agresivo de peróxido de hidrógeno, se desarrolló OCP en la mitad de los casos. Esto destacó la impresionante resistencia de estas células y la dificultad de prevenir su desarrollo. En nuestro segundo estudio, muestras de OCP que se habían desarrollado in vivo, fueron comparadas con nuestras muestras in vitro anteriores para comprender mejor el desarrollo de la OCP. Concluimos que la OCP se debe al proceso fallido por parte de las células residuales de regenerar el cristalino. Esto nos hizo reevaluar nuestro enfoque sobre la prevención de la OCP. En lugar de estudiar distintas formas de prevenir el desarrollo de la OCP farmacológicamente, ahora pretendimos estudiar si las células pudieran regenerar un cristalino transparente. La idea de regenerar el cristalino no es nueva, pero solo se ha observado y estudiado en animales y bebés, nunca en humanos adultos. Con este nuevo objetivo en mente, primero queríamos estudiar si los casos avanzados de OCP desarrollan de forma natural tejido transparente, a pesar de parecer opaco cuando se observa clínicamente. Para hacer esto, extrajimos muestras avanzadas de OCP de tejido ocular de donantes ex vivo y las seccionamos gruesamente para analizarlas sagitalmente. Observamos que en la mayoría de los casos una porción significativa del tejido interno era transparente. Esto apoyó aún más nuestra idea de la regeneración del cristalino como una posible opción de tratamiento futuro. Finalmente, desarrollamos un nuevo modelo de cultivo in vitro que consideramos que favoreciera el desarrollo de células normales del cristalino en lugar de células fibróticas. Realizamos cambios en la preparación quirúrgica de las muestras para aumentaron el número inicial de células, reducir el estrés celular y mejorar el contacto entre las cápsulas anterior y posterior. Sin embargo, no logramos la regeneración del cristalino, pero disminuimos algunos factores relacionados con la OCP fibrótica. Esto resalta la complejidad de este nuevo enfoque. Esta tesis y la idea de la regeneración del cristalino como tratamiento abren muchas nuevas vías de estudio interesantes y tenemos toda la intención de continuar por este nuevo camino.
Cataracts are the world's leading cause of blindness and are due to a progressive opacification of the eye lens. Fortunately, cataracts are easy to treat, however in many cases surgery can lead to a secondary loss of vision, known as posterior capsule opacification (PCO). PCO develops due to a combination of the proliferation, migration, and transdifferentiation of residual lens cells left in the lens capsule, after cataract surgery, resulting in a progressive loss of vision. Many approaches for PCO prevention have been studied, from adjustments to surgical techniques and materials, to pharmacological treatment. Currently the most effective option is to mechanically prevent cells from invading the visual axis. Despite these advances, the development of PCO is still a common post-surgical complication that affects many patients. In this thesis, we used an in vitro lens capsule tissue model to study the development and possible prevention of PCO. In our first study, we simulated the natural progression of PCO in vitro and subsequently tried to prevent it with different substances. However, despite using an aggressive approach of hydrogen peroxide, PCO still developed in half of the cases. This highlighted the impressive resilience of these cells and why prevention is such a difficult task. In our second study, samples of PCO developed in vivo, were compared to our previous in vitro samples in order to better understand the development of PCO. We concluded that PCO is due to a failed attempt of the residual lens cells to regenerate the lens. This made us reevaluate our approach to PCO prevention. Instead of studying ways to prevent the development of PCO pharmacologically, we intended to study whether residual lens epithelial cells could regenerate a transparent lens. The idea of regenerating the lens isn't new, but it has only ever been observed and studied in animals and infants, never in human adults. With this new goal in mind, we first wanted to study whether advanced cases of PCO naturally developed any transparent tissue, despite appearing opaque when observed clinically. In order to do this, we extracted advanced PCO tissue samples from ex vivo donor eye globes and thickly sectioned them in order to analyze them sagittally. We observed that in most cases a significant portion of the inner tissue is transparent. This further supported our idea of adult lens regeneration as a possible future treatment option. Finally, we developed a new in vitro culture model that we believed would favor the development of normal lens cells instead of fibrotic cells. We made changes to the surgical preparation of the samples to increase residual lens cells, reduce the stress to these and improve the contact between the anterior and posterior capsules. However, lens regeneration was not achieved, but we did decrease some factors related to fibrotic PCO. This highlights the complexity of this new approach. This thesis and the idea of lens regeneration as a treatment option, opens up many new interesting avenues of study and we intend to continue along this new path.
Universitat Autònoma de Barcelona. Programa de Doctorat en Biologia Cel·lular
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Long, Amy Carise. "Influence of environmental and chemical factors on cellular signaling in lens epithelial cells." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1186677862.
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