In the period between 1500 to 1700 in Europe, comprehension of the eye’s anatomy, physiology, and pathology significantly expanded, and the relationship between the human eye and knowledge was also fundamentally reformulated. This dissertation tells the story of this transformation through the intersection between medicine and art, and via the eyes and hands of a group of medical and artisanal practitioners in the German speaking lands. From the sixteenth century onwards, an increasing number of people from diverse social classes and professions were engaged in investigating the structure, workings, and disorders of the eye, including surgeons, artisans, physicians, and natural philosophers. Manifold ways of knowing formed ophthalmic knowledge, from practical making and doing to theoretical construction. The understandings and findings were communicated through a wide range of media, not only in texts, but also frequently via images and objects, such as illustrated books, anatomical models, prostheses, and optical devices. They were widely circulated across Europe and collected by scholars, amateurs, and princely rulers alike. Surgeons and artisans were among the most notable yet understudied groups of investigators in this endeavor. They shared expertise in materials, proficiency in manual work, and modes of investigating nature through bodily engagement. With their close collaboration to create pictures and artifacts, they were instrumental in developing insights about the eye. Their image- and object-making put forward a persistent claim about the value of their embodied and experiential knowledge, through which these practitioners undermined the traditional hierarchy of professional structures and scholarly knowledge systems. Knowledge of the eye not only constituted a critical branch of artistic and medical investigation, but was also of wider cultural and epistemological significance. To understand the structure and function of the eye was to reflect on the very foundation of knowledge.

Although it is well known that the pupil responds dynamically to changes in ambient light levels, the results from this dissertation show for the first time that the pupil also responds dynamically to changes in spatially distributed attention. Using a variety of orientating tasks, subjects alternated between focusing attention on a central stimulus and spreading attention over a larger area. Fourier analysis of the fluctuating pupil diameter indicated that: 1) pupil diameter changed at the rate of attention variation, dilating with broadly spread attention and contracting with narrowly focused attention, and 2) pupillary differences required changes in attentional spread; there were no differences in pupil diameter between sustained broad and sustained spread attention. Given that broadly spread attention increases the relative activation of large receptive fields and narrowly focused attention increases the relative activation of small receptive fields (Balz & Hock, 1997), the results of this study indicate that these attentional effects on receptive field activation can be mediated by changes in pupil diameter. That is, under broad attention, the corresponding pupillary dilation observed would increase spherical aberration, blurring the image thereby reducing high spatial frequency information and decreasing the activation of relatively small cortical receptive fields compared to relatively large receptive fields. This increased perception of low spatial frequencies would be beneficial in cases where attention is spread over a large area. Alternatively, under narrow attention the resulting pupillary constriction reduces spherical aberration sharpening the image and preserving high spatial frequency information resulting in a relatively increased response of small receptive fields. / by Lori B. Daniels. / Thesis (Ph.D.)--Florida Atlantic University, 2010. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2010. Mode of access: World Wide Web.

Bestrophins are a family of calcium (Ca²⁺) -activated chloride (Cl⁻) channels (CaCCs) with functional importance in eye physiology. Mutations to the VMD2 gene, which encodes the Best1 protein, cause an array of degenerative eye disorders called bestrophinopathies, which result from aberrant CaCC activity of the Best1 channel in the pigmented epithelium of the retina. While there are four bestrophin paralogs in mammals (Best1-4), the only current structures are of Best1 homologs. The structure of the prokaryotic homolog of Best1 from Klebsiella pneumonia (KpBest) was previously solved in this lab, representing the first structure of a Best1 homolog at the time. This initial study laid the foundational groundwork in the field and contributed significant knowledge to understanding the bestrophin structure-function relationship. Nevertheless, significant questions remain regarding bestrophin function, such as the molecular determinants underlying its Ca²⁺-dependent gating and anion selectivity. This dissertation uses single-particle cryogenic electron microscopy paired with electrophysiology to probe the structure-function relationship of mammalian bestrophins under different buffer conditions and reveals conformational dynamics involved in gating of wild-type channels. Key regions of the channel contributing to its function are described at the atomic level leading to development of a gating model to explain Ca²⁺-dependent activation and inactivation in mammalian bestrophins.

Taurine is the second most abundant amino acid in the CNS after glutamate and its functions have been found largely related to intracellular calcium ([Ca2+]i) modulation, osmoregulation, membrane stabilization, reproduction and immunity. The action of taurine has also been implicated in neurotransmission and neuromodulation though its specific sites of action are not fully understood. Isolated retinal neurons from the larval tiger salamanders (Ambystoma tigrinum) were used as a model to study the neuromodulatory role of taurine in the CNS and to gain insights into its potential sites of action. A combination of techniques was used, including whole-cell patch clamp recording to study taurine's regulation of voltage-gated potassium (K+) and Ca2+ channels and Fluo-4AM Ca2+-imaging to study taurine's regulation of glutamate-induced [Ca2+] I,. Taurine was shown to suppress of glutamate-induced [Ca2+] l, in a dose dependent manner. This suppression was mostly sensitive to the glycine rece ptor antagonist Strychnine but insensitive to any GABA receptor antagonist. The remaining strychnine-insensitive effect was inhibited with the protein kinase A (PKA) inhibitor, PKI, suggesting that there was an additional metabotropic pathway. Moreover, using the protein kinase C (PKC) inhibitor, GF109203X, there was an enhancement in strychnine-insensitive taurine's regulation. Taurine inhibits voltage-gated Ca2+ channels in the retinal neurons and has a dual effect on voltage-gated K+ channels. Taurine causes an increase in K+ current amplitude which is further enhanced with PKI and blocked with GF109203X, suggesting that it is through a PKC-dependent pathway negatively controlled by PKA-dependent pathway. / There is a suppression of K+ current by taurine with intracellular application of GF109203X, suggesting that the reduction is through a PKA-dependent pathway. With both PKC and PKA inhibitors there is no longer an enhancement in maximum amplitude but a shift of volt dependence on a hyperpolarizing direction. Taurine's enhancement of K+ current is blocked by the Kv1.3 subtype antagonist Margatoxin, with Kv1.3 accounting for the majority of delayed-rectifier sustained current in bipolar and amacrine cells, as well as 50% of ganglion cells. Interestingly, the enhancement of K+ current by taurine is blocked by 5HT2A antagonist MDL11939, suggesting that activation of PKC is through this metabotropic serotonin receptor subtype. The suppression of voltage-gated Ca2+ channels is reversed with a combination of MDL11939 and the 5HT1A antagonist NAN-190. These results provide the evidence that the natural effect of taurine in the retinal neurons might be dependent on the activation of both 5HT1A and 5HT2A receptors. The high apparent activity of taurine on 5HT receptors could have important implication for the actions of taurine in central brain in which taurine has been known to be beneficial for improving mental health, as well as learning and memory processes. / by Simon Bulley. / Thesis (Ph.D.)--Florida Atlantic University, 2010. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2010. Mode of access: World Wide Web.

A distrofina é uma das proteínas que formam o complexo glicoproteico necessário para a integridade da fibra muscular e sua disfunção causa uma doença genética letal para os seres humanos, a distrofia muscular de Duchenne (DMD). Além do papel fundamental no tecido muscular, a distrofina é necessária para a fisiologia da retina e, portanto, para o processamento da informação visual. Estudos anteriores mostraram prejuízo assimétrico no eletrorretinograma (ERG), maior para aumento da luminância (via ON) que para diminuição (via OFF). Além disso, prejuízos na visão de cores e contrastes eram mais frequentes e severos em pacientes com alterações genéticas que comprometem a expressão da isoforma Dp260. O objetivo do presente estudo foi verificar através de protocolos eletrofisiológicos e psicofísicos se existiam diferenças nas respostas mediadas pelas vias visuais ON e OFF em jovens com DMD e como estas se relacionavam com o genótipo. Foram avaliados 19 jovens com DMD (idade média = 15,2 ± 3,4 anos) cujos resultados foram comparados com os de sujeitos controles pareados por idade. Os métodos utilizados foram o ERG de campo total e medidas psicofísicas de sensibilidade ao contraste (SC) espacial e temporal de luminância. Protocolos tradicionalmente empregados foram associados a protocolos cujos estímulos visuais ativam, preferencialmente, a via ON ou a via OFF. Para o ERG de campo total foram utilizados seis protocolos: 1. ERG escotópico, 2. ERG fotópico, 3 e 4. ERG mesópico ON e OFF, 5 e 6. ERG fotópico ON e OFF. Para os quatro últimos foram utilizados estímulos intermitentes com modulação da luminância em dente de serra, com aumento rápido de luminância e diminuição gradual (ON) e o contrário (OFF). Para a avaliação psicofísica foi determinada: 1. SC para grades senoidais e SC temporal, e 2. SC a estímulos de tabuleiro de xadrez com aumento (ON) ou diminuição (OFF) da luminância média relativa ao fundo, apresentados com duração curta (sistema magnocelular) ou longa (sistema parvocelular). Os resultados mostraram redução da amplitude da onda-b dos ERGs escotópico e fotópico e prejuízos na SC espacial e temporal de luminância, concordando com a literatura. A contribuição inédita do presente estudo foi mostrar alteração nos ERGs ON e OFF para atividade dos bastonetes e no ERG ON para atividade exclusiva dos cones. Na avaliação psicofísica, houve redução da SC para os protocolos ON sem diferença entre magnocelular e parvocelular. Em conclusão, as alterações encontradas estão principalmente relacionadas com a atividade ON da retina. A alteração psicofísica da SC espacial de luminância de jovens com DMD deve estar relacionada, ao menos em parte, com prejuízos retinianos devidos à ausência da Dp260 ou da própria distrofina total (Dp427). Estudos futuros devem aprofundar a investigação utilizando protocolos do ERG que estimulam, preferencialmente, as vias magnocelular e parvocelular, e ampliar o número de pacientes avaliados para se obter as correlações entre as alterações genéticas e os prejuízos visuais / The dystrophin is one of the proteins that form the glycoprotein complex necessary for the integrity of the muscular fibers. Its dysfunction causes a genetic disease called the Duchenne Muscular Dystrophy (DMD) which is lethal for humans. Besides its fundamental role in the muscle tissues the dystrophin is also necessary in the physiology of the retina, in the processing of visual information. Previous studies have demonstrated asymmetric deviations in the electroretinogram (ERG) of DMDs with bigger changes to stimuli with increasing (ON pathway) than to decreasing (OFF pathway) luminance. Moreover deficiencies in color vision and contrast sensitivity have been more frequent and severe in patients having genetic alterations related to the expression of the Dp260 isoform. The aim of the present study was to apply electrophysiological and psychophysical protocols to verify the suspected alterations in DMD patients regarding the ON and OFF visual pathways and relate the results to their genotypes. 19 DMD patients (mean age = 15.2 ± 3.4 years) were tested and their results were compared to that of an age-matched control group. Fullfield ERG and spatial and temporal luminance contrast sensitivity tests were used during the examinations. Classical protocols were applied together with the ones preferentially stimulating the ON and the OFF visual pathways. The full-field ERG test consisted of six protocols: 1. Scotopic ERG, 2. Photopic ERG, 3. and 4. Mesopic ON and OFF ERG, 5. and 6. Photopic ON and OFF ERG. For the latter four protocols flicker stimuli were used with sawtooth modulation of rapid increase and slower decrease in luminance (ON) and rapid decrease and slower increase in luminance (OFF). The psychophysical evaluation comprised 1. Spatial contrast sensitivity test with sinusoidal gratings and temporal contrast sensitivity test, and 2. Contrast sensitivity tests with checkerboard stimuli with increasing (ON) and decreasing (OFF) luminance relative to the background. These latter were presented for both short (magnocellular system) and long (parvocellular system) durations. In agreement with the literature the results show reduced amplitudes in the ERGs scotopic and photopic b-waves and also impairment in the spatial and temporal contrast sensitivities. This studys novel contribution was the presentation of the alterations in both rod driven ON and OFF ERGs and solely in the cone driven ON ERG. The psychophysical analysis showed reduced contrast sensitivity in the ON protocol similar for both magno- and parvocellular oriented stimuli. In summary the encountered alterations suggest damages in the ON mechanism of the retina. The changes in spatial luminance contrast sensitivity of DMD patients are related, at least partially, to the lack of Dp260 or to the loss of the entire dystrophin (Dp427). Future studies shall investigate this in more details applying ERG protocols to stimulate magno- and parvocellular activities, and increase the number of patients to be able to determine correlations between visual dysfunctions and genetic mutations

A distrofina é uma das proteínas que formam o complexo glicoproteico necessário para a integridade da fibra muscular e sua disfunção causa uma doença genética letal para os seres humanos, a distrofia muscular de Duchenne (DMD). Além do papel fundamental no tecido muscular, a distrofina é necessária para a fisiologia da retina e, portanto, para o processamento da informação visual. Estudos anteriores mostraram prejuízo assimétrico no eletrorretinograma (ERG), maior para aumento da luminância (via ON) que para diminuição (via OFF). Além disso, prejuízos na visão de cores e contrastes eram mais frequentes e severos em pacientes com alterações genéticas que comprometem a expressão da isoforma Dp260. O objetivo do presente estudo foi verificar através de protocolos eletrofisiológicos e psicofísicos se existiam diferenças nas respostas mediadas pelas vias visuais ON e OFF em jovens com DMD e como estas se relacionavam com o genótipo. Foram avaliados 19 jovens com DMD (idade média = 15,2 ± 3,4 anos) cujos resultados foram comparados com os de sujeitos controles pareados por idade. Os métodos utilizados foram o ERG de campo total e medidas psicofísicas de sensibilidade ao contraste (SC) espacial e temporal de luminância. Protocolos tradicionalmente empregados foram associados a protocolos cujos estímulos visuais ativam, preferencialmente, a via ON ou a via OFF. Para o ERG de campo total foram utilizados seis protocolos: 1. ERG escotópico, 2. ERG fotópico, 3 e 4. ERG mesópico ON e OFF, 5 e 6. ERG fotópico ON e OFF. Para os quatro últimos foram utilizados estímulos intermitentes com modulação da luminância em dente de serra, com aumento rápido de luminância e diminuição gradual (ON) e o contrário (OFF). Para a avaliação psicofísica foi determinada: 1. SC para grades senoidais e SC temporal, e 2. SC a estímulos de tabuleiro de xadrez com aumento (ON) ou diminuição (OFF) da luminância média relativa ao fundo, apresentados com duração curta (sistema magnocelular) ou longa (sistema parvocelular). Os resultados mostraram redução da amplitude da onda-b dos ERGs escotópico e fotópico e prejuízos na SC espacial e temporal de luminância, concordando com a literatura. A contribuição inédita do presente estudo foi mostrar alteração nos ERGs ON e OFF para atividade dos bastonetes e no ERG ON para atividade exclusiva dos cones. Na avaliação psicofísica, houve redução da SC para os protocolos ON sem diferença entre magnocelular e parvocelular. Em conclusão, as alterações encontradas estão principalmente relacionadas com a atividade ON da retina. A alteração psicofísica da SC espacial de luminância de jovens com DMD deve estar relacionada, ao menos em parte, com prejuízos retinianos devidos à ausência da Dp260 ou da própria distrofina total (Dp427). Estudos futuros devem aprofundar a investigação utilizando protocolos do ERG que estimulam, preferencialmente, as vias magnocelular e parvocelular, e ampliar o número de pacientes avaliados para se obter as correlações entre as alterações genéticas e os prejuízos visuais / The dystrophin is one of the proteins that form the glycoprotein complex necessary for the integrity of the muscular fibers. Its dysfunction causes a genetic disease called the Duchenne Muscular Dystrophy (DMD) which is lethal for humans. Besides its fundamental role in the muscle tissues the dystrophin is also necessary in the physiology of the retina, in the processing of visual information. Previous studies have demonstrated asymmetric deviations in the electroretinogram (ERG) of DMDs with bigger changes to stimuli with increasing (ON pathway) than to decreasing (OFF pathway) luminance. Moreover deficiencies in color vision and contrast sensitivity have been more frequent and severe in patients having genetic alterations related to the expression of the Dp260 isoform. The aim of the present study was to apply electrophysiological and psychophysical protocols to verify the suspected alterations in DMD patients regarding the ON and OFF visual pathways and relate the results to their genotypes. 19 DMD patients (mean age = 15.2 ± 3.4 years) were tested and their results were compared to that of an age-matched control group. Fullfield ERG and spatial and temporal luminance contrast sensitivity tests were used during the examinations. Classical protocols were applied together with the ones preferentially stimulating the ON and the OFF visual pathways. The full-field ERG test consisted of six protocols: 1. Scotopic ERG, 2. Photopic ERG, 3. and 4. Mesopic ON and OFF ERG, 5. and 6. Photopic ON and OFF ERG. For the latter four protocols flicker stimuli were used with sawtooth modulation of rapid increase and slower decrease in luminance (ON) and rapid decrease and slower increase in luminance (OFF). The psychophysical evaluation comprised 1. Spatial contrast sensitivity test with sinusoidal gratings and temporal contrast sensitivity test, and 2. Contrast sensitivity tests with checkerboard stimuli with increasing (ON) and decreasing (OFF) luminance relative to the background. These latter were presented for both short (magnocellular system) and long (parvocellular system) durations. In agreement with the literature the results show reduced amplitudes in the ERGs scotopic and photopic b-waves and also impairment in the spatial and temporal contrast sensitivities. This studys novel contribution was the presentation of the alterations in both rod driven ON and OFF ERGs and solely in the cone driven ON ERG. The psychophysical analysis showed reduced contrast sensitivity in the ON protocol similar for both magno- and parvocellular oriented stimuli. In summary the encountered alterations suggest damages in the ON mechanism of the retina. The changes in spatial luminance contrast sensitivity of DMD patients are related, at least partially, to the lack of Dp260 or to the loss of the entire dystrophin (Dp427). Future studies shall investigate this in more details applying ERG protocols to stimulate magno- and parvocellular activities, and increase the number of patients to be able to determine correlations between visual dysfunctions and genetic mutations

"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.)

This diploma thesis considers with human vision and human eye. It takes into account both anatomic view and physiology standpoints. There is, among others, description of optical processes occurring in the organ of the sight mentioned in the work. The human eye suffers from optical defects – aberrations – that are able to degrade the retinal image and ultimately visual performance. Substantial part of the text deals with these aberrations. There are also analysed possibilities of their elimination using an inverse aberration. Work also assumes opportunity to optical modeling to calculate distorted images from ocular aberration data. Practical part consist of software application created using Matlab environment ver. 6.5 as well as full documentation. The examples of outputs procured using this application are published. Both software application and detail documentation are included on CD.