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by Hiu-ming Li. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1993. / Includes bibliographical references (leaves 81-88). / SUMMARY --- p.1 / Chapter CHAPTER 1. --- INTRODUCTION --- p.3 / Chapter CHAPTER 2. --- LITERATURE REVIEW --- p.7 / Chapter 2.1. --- Retinal pigment epithelium --- p.7 / Chapter 2.1.1. --- Embryology / Chapter 2.1.2. --- Anatomy and histology / Chapter 2.1.3. --- Growth and aging / Chapter 2.1.4. --- Macular region / Chapter 2.2. --- The photoreceptor outer segment --- p.12 / Chapter 2.3. --- Lipofuscin --- p.13 / Chapter 2.4. --- Lipofuscin in retinal pigment epithelium and retinal photoreceptor disc shedding --- p.14 / Chapter 2.5. --- Possible mechanism for lipofuscin formation in the RPE --- p.22 / Chapter 2.6. --- Age-related lipofuscin accumulation in the RPE --- p.22 / Chapter 2.7. --- Racial difference of RPE lipofuscin concentration --- p.25 / Chapter 2.8. --- RPE lipofuscin and age-related macular degeneration --- p.26 / Chapter CHAPTER 3. --- MATERIALS AND METHODS --- p.28 / Chapter 3.1. --- Histologic Specimens --- p.28 / Chapter 3.2. --- Measuring equipment --- p.28 / Chapter 3.3. --- Software of measurements --- p.31 / Chapter 3.4. --- Light source and filters --- p.31 / Chapter 3.5. --- Control --- p.31 / Chapter 3.6. --- Measurement of autofluorescent Intensity --- p.32 / Chapter 3.7. --- Bleaching (oxidation) of melanin --- p.39 / Chapter CHAPTER 4. --- RESULTS --- p.42 / Chapter 4.1. --- Bleaching test --- p.42 / Chapter 4.2. --- RPE autofluorescence observation in different age --- p.43 / Chapter 4.3. --- RPE autofluorescence observation within individual eyes --- p.45 / Chapter 4.4. --- Topographic distribution of lipofuscin --- p.49 / Chapter 4.5. --- Lipofuscin content at the Foveola --- p.50 / Chapter 4.6. --- The relationship of age and lipofuscin content in total RPE --- p.51 / Chapter 4.7. --- The relationship of age and lipofuscin content in the macular RPE --- p.57 / Chapter 4.8. --- Relationship of age and lipofuscin content in the posterior pole of RPE --- p.59 / Chapter 4.9. --- Relationship of age and lipofuscin content in the temporal RPE --- p.61 / Chapter 4.10. --- Relationship of age and lipofuscin content in the nasal RPE --- p.63 / Chapter 4.11. --- Age related topographic changes --- p.65 / Chapter 4.12. --- The relationship of age and lipofuscin content in the RPE of male --- p.66 / Chapter 4.13. --- The relationship of age and lipofuscin content in the RPE of female --- p.68 / Chapter 4.14. --- Relationship of lipofuscin content in different sex --- p.70 / Chapter CHAPTER 5. --- DISCUSSION --- p.71 / Chapter 5.1. --- Evaluation of method --- p.71 / Chapter 5.2. --- RPE lipofuscin content in different age --- p.71 / Chapter 5.3. --- Topographic distribution of lipofuscin --- p.74 / Chapter 5.4. --- Lipofuscin and age-related macular degeneration in Chinese --- p.78 / REFERENCES --- p.81

Visual function degrades with increasing age, in absence of frank disease, and affects both photopic and scotopic sensitivity. The mechanisms underlying these impairments may be related to biological (e.g., neural, optical) and environmental (e.g., smoking, dietary) factors. Recent evidence suggests that visual function may be improved following retinal carotenoid supplementation, both, in healthy and diseased eyes. Retinal carotenoids accumulate within the retina to form the macular pigment (MP) - a biomarker of antioxidant status of the eye and retinal disease risk. The objectives of this thesis were manyfold. First, the extent of vision loss (particularly scotopic sensitivity) in healthy ageing was examined. The results of this investigation showed that dark adaptation recovery slows with increasing age despite no significant change in visual acuity or fundus appearance. The technique described had excellent repeatability and correlated well with previous research. The potential link between MP and dark adaptation was also examined. The results showed that macular pigment optical density (MPOD) was correlated with a specific parameter of dark adaptation (S2) - a sensitive marker of functional degradation in normal ageing and retinal disease. The main part of this thesis sought to investigate the effect of MP augmentation on visual function in a large group of observers aged between 50 and 90 years old. The baseline data from this clinical trial revealed very interesting findings with regards to unhealthy lifestyle behaviours, health status and statin use. Subjects taking statins were identified (n = 25) and matched with 25 participants not using statins for age and body mass index. It was found that statin users had a higher proportion of males, higher prevalence of current smoking status and poorer general health (e.g. hypertension, high cholesterol and heart disease). Statin users also had significantly reduced MPOD, prolonged photostress recovery time, and deficits in a number of dark adaptation parameters. In a separate analysis of the whole group (n= 74, mean age 65.51), smokers were found to have reduced MPOD, slower S2, higher prevalence of high cholesterol and lower fruit and vegetable intake. MPOD was also reduced among obese subjects. The impact of MP augmentation on visual function in normal older subjects was assessed (n = 74, mean age 65.51) in a 12 month, randomized, double-blind, placebo-controlled study. Active formulation consisted of 20 mg lutein combined with vitamins and minerals. Data were collected at baseline, 6 months and 12 months. The results showed that, despite a 24% MPOD increase in the active group, there were no significant differences between the two groups over the three visits for any of the visual parameters. Given the increasing size of the older adult population in developed countries, research aimed at slowing or reversing age-related declines in vision is much needed both from an economical and psycho-social perspective. The results of the studies presented in this thesis show that lifestyle, health status and certain medications can adversely affect visual function in normal ageing. MP augmentation, however, had no effect on visual function. Further research is warranted, particularly paying close attention to subjects engaging in several unhealthy lifestyle/dietary behaviours, statin users and those with low MPOD and suboptimal visual function.

The optical density of human macular pigment was measured for 50 observers ranging in age from 10 to 90 years. The psychophysical method required adjusting the radiance of a 1°, monochromatic light (400–550 nm) to minimize flicker (15 Hz) when presented in counterphase with a 460 nm standard. This test stimulus was presented superimposed on a broad-band, short-wave background. Macular pigment density was determined by comparing sensitivity under these conditions for the fovea, where macular pigment is maximal, and 5° temporally. This difference spectrum, measured for 12 observers, matched Wyszecki and Stiles's standard density spectrum for macular pigment. To study variation in macular pigment density for a larger group of observers, measurements were made at only selected spectral points (460, 500 and 550 nm). The mean optical density at 460 nm for the complete sample of 50 subjects was 0.39. Substantial individual differences in density were found (ca. 0.10–0.80), but this variation was not systematically related to age.

Aged-related macular degeneration (AMD) is a common eye condition among people older than 65 years and is a leading cause of vision loss. It gradually destroys the macula, the part of the eye that provides sharp, central vision needed for seeing objects clearly. This study aims to test the hypothesis that the morphology of retina pigment epithelium, a key site of AMD pathology, can reflect the various stresses aging and AMD progression impose. We first identify and separate the young and old age group for mouse eyes. Then we classify, the mouse eyes using two genotypes (C57BL/6L, RD10), and two age group (young, old).We show that without dimensional reduction, the cell area and shape measures do not provide good classification of the mouse eyes. But with the dimension reduction at the eye level, the cell area and shape measures provide excellent classification for mouse genotype and age.

Phytochemical composition, antioxidant activity, pigment stability, bioactive properties, and in-vitro absorption of polyphenolics in acai fruit (Euterpe oleracea Mart.) were investigated. Detailed characterization of phenolic compounds present in acai fruit, acai fruit pulp, and a polyphenolic-enriched acai oil were conducted by HPLCESI- MSn analyses and their stability and influence on antioxidant capacity determined. Anthocyanins were predominant in acai fruits, which also contained several flavone and flavonol glycosides, flavanol derivatives, and phenolic acids. In-vitro absorption and antiproliferative effects of phytochemical extracts from acai pulp and acai oil were determined as a function of chemical composition. Polyphenolic mixtures from both acai pulp and acai oil extracts significantly inhibited HT-29 colon cancer cell proliferation, also inducing the generation of reactive oxygen species. In-vitro intestinal absorption using Caco-2 cell models demonstrated that phenolic acids and monomeric flavanol derivatives are readily transported through cell monolayers in-vitro. The influence of polyphenolic cofactors on the stability of anthocyanins in acai fruit under varying conditions of temperature and pH was evaluated. Significant time, temperature, and pH-dependent anthocyanin losses were observed in all models, yet the presence of phenolic acids, procyanidins, and flavone-C-glycosides had a positive influence on anthocyanin stability. External addition of flavone-C-glycosides significantly enhanced visual color, increased anthocyanin stability during exposures to high pH or storage temperatures, and had comparable effects to those of a commercial anthocyanin enhancer. Anthocyanin polymerization reactions occurring during storage of acai fruit juice models were investigated and potential mechanisms and reaction products identified. Polymeric anthocyanin fractions contained several anthocyanin-flavanol adducts based on cyanidin or pelargonidin aglycones and their presence was related to increased anthocyanin sulfite bleaching resistance and to the appearance of large, unresolved peaks in HPLC chromatograms. A reaction mechanism involving the nucleophilic addition of anthocyanins in their hydrated form to flavanol carbocations resulting from cleavage of interflavanic bonds was proposed for the formation of flavanol-anthocyanin adducts in acai fruit juices. Antiproliferative activity and in-vitro absorption of monomeric and polymeric anthocyanin fractions were also evaluated. Both fractions inhibited HT-29 colon cancer cell growth in a similar, concentration-dependent manner, yet in-vitro absorption trials using Caco-2 intestinal cell monolayers indicated the presence of anthocyanin polymers may influence anthocyanin absorption in acai fruit products.

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To determine whether exposure to simulated microgravity (SMG) affects cranial neural crest (CNC)-derived tissues, zebrafish embryos were exposed to SMG starting at one of three developmental stages corresponding to CNC migration. Juvenile and adult fish were analyzed after exposure to SMG using statistics and geometric morphometrics for changes in melanophore surface area and number, and changes in skull morphology. Analyses reveal an initial increase in the surface area of melanophores present on the dorsal view of the juvenile skull and a decrease in melanophore number over the period of a week. Additionally, buckling is observed in CNC-derived frontal bones in juvenile fish after exposure. The effects on the melanophores are transient and the effects on CNC-derived bones are short-term. Surprisingly, severe long-term effects occurred in mesoderm-derived bones, such as the parasphenoid. In summary, exposure to SMG affects both CNC- and mesoderm-derived tissues in the juvenile and adult zebrafish head.

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Typescript. / Thesis (Ph. D.)--University of Hawaii at Manoa, 1984. / Bibliography: leaves 181-186. / Microfiche. / lMaster negative: Microfiche MS33173. / xiii, 186 leaves, bound ill. 29 cm