Thesis (Ph. D.)--University of Washington, 2006. / Vita. Includes bibliographical references (leaves 88-101).

Cerebral ischemia is defined as a decrease in blood flow to the brain. It is most often caused by obstruction of a cerebral blood vessel, and is recognized by the World Health Organization as the leading cause of serious adult disability and one of the top three causes of adult death worldwide. Most survivors demonstrate partial restitution of function over time, but the underlying recovery mechanism(s) remain unclear especially in a subset of patients with persistent neurological morbidities despite normal-appearing brain on neuroimaging. The optimal way to understand any human disease state is via clinical studies. Unfortunately, well-controlled experiments in humans are difficult due to small patient populations, the presence of numerous confounding variables, and ethical issues associated with invasive or discomforting experimental procedures. Anesthetized animal models of cerebral ischemia afford a means of avoiding the above difficulties. However, anesthesia and physiological perturbations that occasionally follow brain ischemia may affect the reliability of certain tools used to study this disease, such as functional magnetic resonance imaging (fMRI). Therefore, the central goals of this thesis were: 1) to evaluate the feasibility of performing fMRI in anesthetized and awake animals, 2) to assess fMRI responses under various perturbations of cerebral perfusion and tissue oxygenation in order to identify key factors that may modulate functional signal changes following ischemia, and 3) to utilize fMRI, behavioral tests and histology in an anesthetized animal model of transient focal cerebral ischemia to explore postischemic changes in brain pathology/function and how they relate to changes in behavior. In the first study of this dissertation, I report the evaluation of fMRI responses in anesthetized and awake animals. Anesthesia is frequently used in animal models of cerebral ischemia, but is known to alter brain perfusion and metabolism which may, in turn, affect fMRI responsivity. Perfusion-based fMRI was used to evaluate cerebral blood flow (CBF) and blood oxygenation level-dependent (BOLD) responses to hypercapnia in awake and isoflurane-anesthetized rats. Hypercapnia produced significant CBF and BOLD fMRI signal changes throughout the cerebrum in awake and isoflurane-anesthetized groups. These results show that perfusion-based fMRI can successfully detect stimulus-evoked hemodynamic changes in the brains of both conscious and isoflurane-anesthetized animals. The second study of this dissertation: 1) investigates the effects of alterations in cerebral perfusion and oxygenation on fMRI signal changes, and 2) examines the self-consistency of an imaging-based formalism for the calculation of the cerebral metabolic rate of oxygen (CMRO2). Functional MRI responses to a stimulus can be described in terms of relative or absolute signal change. A relative fMRI response is defined as a percent-change relative to its own respective baseline value. An absolute fMRI response is defined as a quantitative change relative to a single fixed baseline value that serves as a control. Thus, an absolute fMRI signal change is largely independent of the baseline state and may more accurately index brain activity when baseline fMRI signals change significantly over time due to, for example, hemodynamic-metabolic disturbances that occur during and/or after brain ischemia. To address these issues, the effects of inspired hypoxic, normoxic, hyperoxic, and hypercapnic gases on baseline and forepaw stimulation-evoked changes in BOLD and CBF fMRI signals were examined in isoflurane-anesthetized rats. Relative fMRI responses to forepaw stimulation varied-whereas. absolute responses were similar--across gas conditions. These results demonstrate that absolute measurements of fMRI signal change may lend a more accurate measure of brain activity during states of altered basal physiology as well as support the self-consistency of the imaging-based CMRO2 formalism under these conditions. The third and last study of this dissertation utilized multimodal MRI, behavioral tests, and histology at acute to chronic periods following transient middle cerebral artery occlusion (tMCAO) in the rat to examine the evolution of pathological, functional, and behavioral parameters following transient focal cerebral ischemia. MRI was used to track the evolution of brain pathology and function following cerebral ischemia, and it was found that the cerebral sensorimotor network, critical for sensory and motor behavioral functions, showed profoundly abnormal signal changes that required up to one day to normalize. Adhesive removal, forepaw placement and beam-walk behavioral tests demonstrated sensorimotor dysfunctions that gradually improved but remained long after the recovery of MRI parameters. Postmortem histology confirmed the presence of selective neural cell death within the sensorimotor network at time points when behavior was abnormal. These results suggest that subtle postischemic pathological changes in the brain undetectable by MRI may be responsible for persistent behavioral deficits-a finding which may be relevant to a clinical subset of patients with persistent neurological morbidities despite negative MRI results following cerebral ischemia.

INTRODUÇÃO: A microanastomose vascular é um componente importante na cirurgia de transferência livre de tecidos. Atualmente, a técnica de sutura convencional ainda é considerada o padrão ouro, no entanto, ela apresenta alguns inconvenientes por ser tecnicamente difícil, consumir muito tempo e ter uma longa curva de aprendizado. Na busca de uma técnica mais fácil e rápida, métodos alternativos de anastomose são estudados incluindo a cola de fibrina. Apesar dos bons resultados publicados, a sua aceitação na prática clínica ainda é limitada. Controvérsias a cerca de sua trombogenicidade e resistência mecânica geram dúvidas em relação a sua segurança. A ausência de um modelo experimental mais fidedigno impede que os potenciais benefícios de sua aplicação clínica sejam apreciados. O objetivo deste estudo é esclarecer essas controvérsias e estudar os benefícios da aplicação da cola de fibrina em um ambiente que simule a prática clínica. MÉTODOS: O modelo experimental utilizado foi a transferência livre de um retalho inguinal para a região cervical anterior. A circulação do retalho era restaurada através de microanastomoses vasculares entre as artérias femoral e carótida (término-lateral) e entre as veias femoral e jugular externa (término-terminal). Utilizamos 20 coelhos que foram divididos em dois grupos (n= 10) de acordo com a técnica de sutura empregada: Grupo I (sutura convencional) e Grupo II (sutura com cola). RESULTADOS: A aplicação da cola de fibrina reduziu significativamente o número de pontos necessários para se completar as anastomoses, 4 pontos a menos nas artérias e 4,5 pontos a menos nas veias. No Grupo I, a média do tempo de anastomose arterial foi de 17,21 minutos, contra 12,72 minutos no Grupo II. Nas anastomoses venosas, a média de tempo no Grupo I foi de 22,93 minutos, contra 16,57 minutos no Grupo II. A aplicação da cola de fibrina também diminuiu o tempo de isquemia do retalho e o tempo de cirurgia em 11,5 minutos e 15,67 minutos, respectivamente. A taxa de sobrevida do retalho foi de 90% nos dois grupos. CONCLUSÕES: A aplicação da cola de fibrina em microanastomoses vasculares demonstrou ser confiável e eficiente no presente estudo. / INTRODUCTION: Microvascular anastomosis is an important component of the free flap surgical procedure. Currently, the conventional suture is still considered the gold standard technique. However, it presents some problems for being technically demanding, time consuming and with a long learning curve. In looking for an easier and faster technique, alternative methods of anastomosis were studied including the fibrin glue. Despite the good results reported in the literature, its acceptance in the clinical setting is still small Controversies regarding its thrombogenicity and mechanical resistance create some concerns about its safeness. The absence of a more realistic experimental model has not allow a full aprecciation of its potencial benefits in clinical use. The aim of this study is clarify these controversies and demonstrate the advantages of fibrin glue application in an environment that can reproduce the clinical practice. METHODS: A free inguinal flap transfer to the anterior cervical region was used as experimental model. The circulation of the flap was restored by means of microvascular anastomosis between the femoral and carotid arteries (end-to-side) and between the femoral and jugular veins (end-to end). The procedures were performed in 20 rabbits that were divided into two groups (n= 10) according to the anastomosis technique: Group I (conventional) and Group II (fibrin glue). RESULTS: The application of fibrin glue significantly reduced the amount of sutures required to complete the anastomoses: 4 less sutures in the arteries and 4,5 less sutures in the veins. In Group I, the mean arterial anastomosis time was 17,21 minutes against 12,72 minutes in Group II. In the veins, the mean anastomosis time in Group I was 22,93 minutes against 16,57 minutes in Group II. The application of fibrin glue also reduced the flap ischemic time and the total operative time by 11,5 minutes and 15,67 minutes, respectively. The flaps\' survival rate was 90% in both groups. CONCLUSIONS: The application of fibrin glue in microvascular anastomoses was reliable and effective in this study.

INTRODUÇÃO: A conjuntivite alérgica é a forma mais comum de doença alérgica que afeta o olho. Neste trabalho, desenvolvemos um modelo murino reprodutível e simular a doença humana, para possibilitar o estudo dos mecanismos fisiopatológicos da conjuntivite alérgica crônica. MÉTODOS: Imunizamos os camundongos BALB/c e C57Bl/6 com extrato do ácaro Dermatophagoides pteronyssinus (Dpt). Foi realizada a dissecção dos linfonodos ilíacos e para-aórticos, e a enucleação dos olhos. O plasma obtido pela punção cardíaca foi utilizado para a dosagem de IgE e IgG totais e específicas para Dpt. Os olhos enucleados foram enviados para estudo anátomo-patológico da conjuntiva e córnea. RESULTADOS: 1) Houve uma diferença estatisticamente significante entre as duas linhagens (BALB/c e C57Bl/6) para os grupos imunizados com 5 ?g e 500 ?g na gradação clínica e histopatológica, dosagens de IgE Total e Específica, proliferação de linfócitos específica para Dpt e IgG Específica, e na dosagem das IL-5, IL-8 e IL-13; 2) Os níveis de IgG Total não se mostraram significantes para as duas linhagens nos grupos imunizados com 5 ?g e 500 ?g; 3) Os níveis de IL-4 e IL-10 tiveram uma diferença significante nos animais da linhagem BALB/c imunizados com 5 ?g e 500 ?g, mas não nos camundongos da linhagem C57BI/6; 4) Os níveis de IFN-? foram maiores nos camundongos C57BI/6 que receberam as menores quantidades de antígeno. Porém nos camundongos BALB/c o fenômeno foi o inverso; 5) O exame histológico revelou afilamento corneano, infiltrado linfocítico corneano e conjuntival, degeneração da conjuntiva e úlceras de córnea nos animais que obtiveram as maiores gradações clínicas da doença (camundongos BALB/c imunizados com 500 ?g de Dpt e camundongos C57Bl/6 imunizados com 5 ?g. CONCLUSÃO: Desenvolveu-se um modelo simples e reprodutível de conjuntivite alérgica crônica do Dermatophagoides pteronyssinus depois de repetidas exposições ao antígeno, o qual apresenta manifestações clínicas similares à doença humana, e serve como modelo de estudo dos mecanismos imunológicos envolvidos no desenvolvimento da doença / INTRODUCTION: Allergic conjunctivitis is the most common form of allergic disease that affects the eye. In this study we developed a reproducible mouse model and simulated human disease to enable the study of physiopathologic mechanisms of chronic allergic conjunctivitis. METHODS: We immunized BALB/c and C57B1/6 mice with Dermatophagoides Pteronyssinus (Dpt) dust mite extract. The iliac and paraaortic lymph nodes were dissected and the eyes were enucleated. The plasma obtained by cardiac puncture was used to measure Total and Specific IgE and IgG and Dpt-specific. Lymph node cells were used to measure Dpt specific proliferation cytokine detection in the culture supernatant. Eyes were enucleated for histopathological analysis of the conjunctiva and cornea. RESULTS: 1) There was a statistically significant difference between the 2 strains (BALB/c and C57B1/6) for the 2 groups immunized with 5?g and 500?g in the clinical and histopathological score, Total and Specific IgE dosages, proliferation Dpt-specific lymphocytes, dust mite Specific IgG, and in the levels of IL-5, IL-8 and IL-13; 2) The level of Total IgG was not significantly different between the 2 lineages in the groups immunized with 5?g and 500?g; 3) The levels of IL-4 and IL-10 showed a significant difference in BALB/c mice sensitized with 5?g and 500?g, but not in C57B1/6 mice; 4) The IFN-? levels were higher in C57B1/6 mice that received the smallest quantity of antigen. But among BALB/c mice the phenomenon was inversed; 5) The histological examination revealed that there was a tapering of the cornea, lymphocytic infiltration of the cornea and conjunctiva, conjunctival degeneration and corneal ulcers in the animals that developed the highest clinical scores of disease (BALB/c immunized with 500 ug of Dpt and C57Bl/6 immunized with 5 ?g of Dpt). Conclusion: A simple and reproducible model of chronic allergic conjunctivitis to Dermatophagoide pteronyssinus was developed after repeated exposure to the allergen, which exhibit similar clinical manifestations as human disease, therefore serving as a template to study the immunological mechanisms involved in the development of disease

Wong, Siu Lun. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (leaves 129-141). / Abstracts in English and Chinese. / Abstract --- p.i / Abstract (Chinese version) --- p.iii / Acknowledgements --- p.iv / List of Abbreviations --- p.v / List of Tables --- p.vii / List of Figures --- p.viii / Chapter 1. --- INTRODUCTION / Chapter 1.1 --- Neurodegenerative disorders - a brief overview --- p.1 / Chapter 1.2 --- Polyglutamine diseases --- p.2 / Chapter 1.3 --- Microscopically visible polyglutamine protein aggregates and its relation to toxicity --- p.7 / Chapter 1.4 --- Polyglutamine protein conformers and their relation to toxicity --- p.10 / Chapter 1.5 --- Modeling polyglutamine diseases in Drosophila / Chapter 1.5.1 --- GAL4/UAS spatial transgene expression system in Drosophila --- p.14 / Chapter 1.5.2 --- Temporal control of GAL4/UAS transgene expression system in Drosophila --- p.16 / Chapter 1.5.3 --- Drosophila as a model to study human pathologies --- p.19 / Chapter 1.5.4 --- Drosophila as a model to study polyglutamine diseases --- p.21 / Chapter 1.6 --- Aims of study --- p.26 / Chapter 2. --- MATERIALS AND METHODS / Chapter 2.1 --- Drosophila culture and manipulation / Chapter 2.1.1 --- Drosophila culture --- p.27 / Chapter 2.1.2 --- Phenotypic examination of adult external eye degeneration --- p.27 / Chapter 2.1.3 --- Pseudopupil assay of adult retinal degeneration and observation of green fluorescent protein in adult eyes --- p.28 / Chapter 2.2 --- Semi-quantitative Reverse Transcription-Polymerase Chain Reaction / Chapter 2.2.1 --- RNA extraction from adult Drosophila heads --- p.30 / Chapter 2.2.2 --- DNase treatment of extracted RNA --- p.31 / Chapter 2.2.3 --- Reverse transcription-Polymerase Chain Reaction (RT-PCR) --- p.31 / Chapter 2.2.4 --- Agarose gel electrophoresis --- p.33 / Chapter 2.3 --- Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophoresis (SDS-PAGE) / Chapter 2.3.1 --- Protein extraction from adult Drosophila heads --- p.33 / Chapter 2.3.2 --- Preparation of SDS-polyacrylamide gel and electrophoresis --- p.34 / Chapter 2.3.3 --- Western blotting --- p.35 / Chapter 2.3.4 --- Immunodetection --- p.36 / Chapter 2.4 --- Immunoprecipitation --- p.38 / Chapter 2.5 --- Filter retardation assay --- p.39 / Chapter 2.6 --- Isolation and solubilization of SDS-insoluble protein --- p.40 / Chapter 2.7 --- Sucrose gradient sedimentation --- p.41 / Chapter 2.8 --- Preparation of Drosophila tissues for immunofluorescence analysis / Chapter 2.8.1 --- Dissection and immunostaining of Drosophila larval imaginal eye discs --- p.42 / Chapter 2.8.2 --- Cryosectioning and immunostaining of adult Drosophila heads --- p.44 / Chapter 2.9 --- Atomic force microscopy --- p.47 / Chapter 2.10 --- Reagents and buffers / Chapter 2.10.1 --- Reagents for Drosophila culture --- p.48 / Chapter 2.10.2 --- Reagents for RT-PCR --- p.52 / Chapter 2.10.3 --- Reagents for SDS-PAGE --- p.54 / Chapter 2.10.4 --- Reagents for immunoprecipitation --- p.57 / Chapter 2.10.5 --- Reagents for filter retardation assay --- p.57 / Chapter 2.10.6 --- Reagents for isolation and solubilization of SDS-insoluble protein --- p.58 / Chapter 2.10.7 --- Reagents for sucrose gradient sedimentation --- p.58 / Chapter 2.10.8 --- Reagents for immunofluorescence --- p.59 / Chapter 3. --- RESULTS / Chapter 3.1 --- Establishment of an inducible transgenic Drosophila model of polyglutamine diseases / Chapter 3.1.1 --- Introduction --- p.60 / Chapter 3.1.2 --- Results / Chapter 3.1.2.1 --- GAL80ts-mediated inducible expression of expanded polyglutamine protein in Drosophila / Chapter 3.1.2.1.1 --- GAL80ts controls GAL4/UAS-mediated polyQ protein expression --- p.61 / Chapter 3.1.2.1.2 --- Inducible expression of SDS-soluble expanded polyglutamine protein --- p.64 / Chapter 3.1.2.1.3 --- Inducible expression of expanded polyglutamine protein accumulates gradually in form of SDS-insoluble protein --- p.66 / Chapter 3.1.2.1.4 --- Inducible expression of expanded polyglutamine protein results in progressive accumulation of microscopically visible aggregates --- p.68 / Chapter 3.1.2.2 --- Inducible expression of expanded polyglutamine protein causes late-onset progressive neuronal degeneration in Drosophila / Chapter 3.1.2.2.1 --- Inducible expression of expanded polyglutamine protein leads to late-onset progressive deterioration of photoreceptor neurons --- p.68 / Chapter 3.1.2.2.2 --- Inducible expression of expanded polyglutamine protein neither causes external eye degenerative phenotype nor disrupts gross retinal morphology despite deterioration of photoreceptor neurons --- p.72 / Chapter 3.1.2.3 --- Co-expression of caspase inhibitor P35 suppresses polyglutamine-induced neuronal degeneration --- p.72 / Chapter 3.1.2.4 --- Co-expression of molecular chaperone Hsp70 suppresses polyglutamine-induced neuronal degeneration --- p.74 / Chapter 3.1.2.5 --- Inducible expression of expanded polyglutamine protein results in biphasic expression of molecular chaperone Hsp70 in Drosophila --- p.76 / Chapter 3.1.3 --- Discussion --- p.76 / Chapter 3.2 --- Involvement of microscopically visible polyglutamine aggregates in neurodegeneration / Chapter 3.2.1 --- Introduction --- p.83 / Chapter 3.2.2 --- Results / Chapter 3.2.2.1 --- Effect of Hsc70-K71S on microscopically visible polyglutamine aggregates and neuronal degeneration / Chapter 3.2.2.1.1 --- Co-expression of Hsc70-K71S reduces the level of microscopically visible polyglutamine aggregates --- p.83 / Chapter 3.2.2.1.2 --- Co-expression of Hsc70-K71S does not alter polyglutamine transgene expression --- p.84 / Chapter 3.2.2.1.3 --- Co-expression of Hsc70-K71S does not modify polyglutamine-induced neuronal degeneration --- p.87 / Chapter 3.2.2.2 --- Microscopically visible polyglutamine aggregates do not correlate with neuronal degeneration --- p.90 / Chapter 3.2.3 --- Discussion --- p.93 / Chapter 3.3 --- Detection of small SDS-insoluble expanded polyglutamine protein species and its association with neurodegeneration / Chapter 3.3.1 --- Introduction --- p.97 / Chapter 3.3.2 --- Results / Chapter 3.3.2.1 --- Accumulation of SDS-soluble expanded polyglutamine protein does not correlate with neuronal degeneration --- p.98 / Chapter 3.3.2.2 --- Identification of small SDS-insoluble expanded polyglutamine protein species / Chapter 3.3.2.2.1 --- Accumulation of total SDS-insoluble expanded polyglutamine protein positively correlates with progressive neuronal degeneration --- p.99 / Chapter 3.3.2.2.2 --- Accumulation of large SDS-insoluble expanded polyglutamine protein does not correlate with neuronal degeneration --- p.99 / Chapter 3.3.2.2.3 --- Accumulation of small SDS-insoluble expanded polyglutamine protein correlates with neuronal degeneration --- p.104 / Chapter 3.3.3 --- Discussion --- p.107 / Chapter 3.4 --- Biophysical characterization of small SDS-insoluble expanded polyglutamine protein species / Chapter 3.4.1 --- Introduction --- p.109 / Chapter 3.4.2 --- Results / Chapter 3.4.2.1 --- Separation of expanded polyglutamine protein species by sucrose gradient sedimentation --- p.110 / Chapter 3.4.2.2 --- Morphological studies of small SDS-insoluble expanded polyglutamine protein species by atomic force microscopy --- p.112 / Chapter 3.4.3 --- Discussion --- p.118 / Chapter 4. --- GENERAL DISCUSSION --- p.124 / Chapter 5. --- CONCLUSION --- p.127 / Chapter 6. --- REFERENCES --- p.129

Conclusion. The present results indicate that, baicalein with optimal dosage of 30 muM suppressed collagen deposition in AngII stimulated SHR CF cultures. In animal model of hypertension, high dose of baicalein feeding for 12 week showed optimal antifibrotic effect in hypertensive hearts. (Abstract shortened by UMI.) / For in-vivo study, comparing to control group, HW/BW (x1000) of SHR was significantly reduced in 12 weeks-high dose baicalein and (-0.78+/-0.23, p=0.014) 12 weeks-Valsartan group (-0.71+/-0.22, p=0.021), however, no significant change was observed in the LW/BW ratio. / In Blood pressure control, no effects on attenuation of SBP were observed after 4 weeks and 12 weeks daily administration of baicalein, only 12 weeks feeding of Valsartan significantly down-regulated the systolic blood pressure by -19.25+/-10.09 mmHg, p=0.049. / In the in-vivo study, SHR was used as a model of genetic hypertension. The objectives were: firstly, to determine the efficacy of baicalein in the prevention of myocardial fibrosis (interstitial fibrosis) in SHR, & compared with WKY rats as normal controls. Secondly, to determine if over-expression of pro-collagen I (and III, if any) gene in the ventricles could be normalized by baicalein. Thirdly, to determine if left ventricular hypertrophy in SHR is improved by baicalein. Furthermore, to determine if blood pressure and blood biochemistry parameters (plasma level of brain natriuretic peptides (BNP), and serum alanine aminotransferase (ALT), aspartate aminotransferase (AST) level could be alternated by baicalein. Besides, to determine the body weight (BW), heart weight to body ratio (HW/BW), liver weight to body weight ratio (LW/BW), serum AST and ALT level could be alternated by baicalein. Finally to evaluate by echocardiography if there are changes of ivss and ivsd in SHR after administration of baicalein. / Keywords. baicalein, wogonin, collagen, cardiac fibrosis, hypertension / Objectives. In the in-vitro study, cardiac fibroblast culture was prepared from neonatal SHR and WKY rats. The objectives were multi-fold: firstly, to determine over-expression of pro-collagen I mRNA (and III, if any) in cardiac fibroblasts cultures could be normalized by baicalein and wogonin after AngII activation. Secondly, to evaluate the efficacy of baicalein and wogonin on the suppression of total collagen protein production in cardiac fibroblasts cultures after AngII activation. Thirdly, to evaluate the mechanism (in protein level) of baicalein and wogonin on regulating collagen deposition in cardiac fibroblasts after AngII activation. Furthermore, to determine if there were any effects on cytotoxicity and membrane integrity of baicalein and wogonin towards cardiac fibroblasts cultures. Finally, to determine the optimal concentration of baicalein and wogonin for the above actions in-vitro. / Results. For in-vitro study, incubation of AngII resulted in significant up-regulation of COL-I and COL-III mRNA and total collagen protein production. Addition of either baicalein or wogonin significantly suppressed the mRNA synthesis and total collagen protein in CF with an optimal dosage of 30 muM. No effects on viability and membrane integrity were observed on baicalein and wogonin towards cardiac fibroblasts cultures. / Kong, Kam Chuen Ebenezer. / Advisers: Cheuk-Man Yu; Gabriel W. K. Yip. / Source: Dissertation Abstracts International, Volume: 71-01, Section: B, page: 0242. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 176-204). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese.

As exogenously administered RA suppressed the expression of the RA synthesizing enzymes, further investigation on whether this would lead to deficiency in endogenous RA concentrations was conducted. Results showed that exogenously administered RA significantly reduced the endogenous RA level in the head region with C57 embryos showing a greater reduction than ICR embryos. / In addition, detailed morphological and histological studies were conducted to determine if RA treatment caused early embryonic changes with strain difference. When compared with ICR embryos, C57 embryos exhibited more pronounced responses to RA, including developmental retardation, underdevelopment of the anterior neural plate and absence of or smaller optic pit/optic vesicle formation. However, RA treatment did not cause abnormal apoptosis in the early stages in both strains. / Since the teratogenic effect of RA is highly developmental stage-dependent, it is possible that there is a difference in the developmental stage between these 2 mouse strains at the time of RA injection. Indeed, it was found that the developmental stage of ICR embryos was approximately 6 hours ahead of C57 embryos. However, the role that this factor plays in the differential strain susceptibility to RA can be excluded since C57 fetuses were still 3 times more susceptible to developing anophthalmia/microphthalmia than ICR fetuses that were subject to RA treatment at equivalent developmental stages. Comparison of susceptibility to RA-induced anophthalmia/microphthalmia was also made among heterozygous fetuses obtained from reciprocal matings between C57 and ICR male and female mice, and those in homozygous ICR and C57 fetuses. Results showed that the C57 strain has conferred both genetic predisposition and maternal effects in increasing the embryo's susceptibility to RA-induced ocular defects. / Since the type of RA-induced ocular defects mimic those that developed in Raldh2 null mutant embryos, the effect of RA treatment on the expression of RA synthesizing enzymes, Raldh2 and Raldh3, and the RA-inducible gene Cyp26a1, as well as some early eye development genes were examined. Exogenously administered RA reduced the mRNA expression levels of Raldh2, Raldh3 and Cyp26a1 in the head region, with C57 embryos showing a greater reduction than ICR embryos. / Taken together, results of this thesis suggest that there is a strain difference in susceptibility to RA-induced ocular defects in which exogenously applied RA suppresses the expression of RA synthesizing enzymes and leads to endogenous RA deficiency. This finding may shed light on understanding why both excess and deficiency of RA can lead to similar types of ocular defects. / To determine if there are strain differences in the susceptibility to RA-induced ocular defects, two mouse strains were used. They are C57BL/6J (C57), mice that spontaneously develop ocular defects and ICR mice, which are not prone to developing ocular defects. Detailed time and dose response studies were conducted and eye defects were examined in near-term fetuses. C57 fetuses were found to be significantly more susceptible to RA-induced anophthalmia/microphthalmia than ICR fetuses. / Vitamin A (retinol) and its most active metabolite, all- trans retinoic acid (RA) is essential for vision in the adult and for eye development in the embryo. It is well documented that in humans, excess intake or deficiency of vitamin A or RA is associated with congenital ocular defects such as microphthalmia. However, the underlying mechanism remains unclear. The aim of this study is to examine the pathogenic mechanism of RA-induced developmental ocular defects. / Lau, Wing Sze Josephine. / Source: Dissertation Abstracts International, Volume: 71-01, Section: B, page: 0240. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 186-211). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese.

A confocal scanning laser ophthalmoscope (CSLO) was used to image the axonal and dendritic aborizations of RGCs in the Thy-1 YFP mice. With quantitative analysis of cell body area, axon diameter, dendritic field, number of terminal branches, total dendritic branch length, branching complexity, symmetry and distance from the optic disc, the morphologies of RGCs and the patterns of axonal and dendritic degeneration were analyzed. After optic nerve crush, RGC damage was observed prospectively to begin with progressive dendritic shrinkage, followed by loss of the axon and the cell body. Similar pattern of RGC degeneration was observed after 90 minutes of retinal ischemia although no morphological changes were detected when the duration of ischemia was shortened to 30 minutes. The rate of dendritic shrinkage was variable and estimated on average 2.0% per day and 11.7% per day with linear mixed modeling, after optic nerve crush and retinal ischemic injury, respectively. RGCs with a larger dendritic field had a slower rate of dendritic shrinkage. / In summary, we demonstrated that dendritic shrinkage could be evident even before axonal degeneration after optic nerve crush and retinal ischemic injury. We have established a methodology for in vivo and direct visualization of RGCs and retinal microglia, which could provide reliable and early markers for neuronal damage. Measuring the rate of dendritic shrinkage and tracking the longitudinal activation of microglia would provide new paradigms to study the mechanism of neurodegenerative diseases and offer new insights in testing novel therapies for neuroprotection. / Progressive neuronal cell death and microglial activation are the key pathological features in most neurodegenerative diseases. While investigating the longitudinal profiles of neuronal degeneration and microglial activation is pertinent to understanding disease mechanism and developing treatment, analyzing progressive changes has been obfuscated by the lack of a non-invasive approach that allows long term, serial monitoring of individual neuronal and microglial cells. Because of the clear optical media in the eye, direct visualization of the retinal ganglion cells (RGCs) and microglia is possible with high resolution in vivo imaging technique. In this study, we developed experimental models to visualize and characterize the cellular morphology of RGCs and retinal microglia in vivo in the Thy-1 YFP and the CX3CR1 +/GFP transgenic mice, described the patterns of axonal and dendritic shrinkage of RGCs, discerned the dynamic profile of microglial activation and investigated the relationship between RGC survival and microglial activation after optic nerve crush and retinal ischemic injury induced by acute elevation of intraocular pressure. / The longitudinal profile of microglial activation was investigated by imaging the CX3CR1GFP/+ transgenic mice with the CSLO. Activation of retinal microglia was characterized with an increase in cell number reaching a peak at a week after optic nerve crush and retinal ischemic injury, which was followed by a gradual decline falling near to the baseline at the 4 th week. The activation of retinal microglia was proportional to the severity of injury. The number of RGCs survival at 4 weeks post-injury was significantly associated with the number of activated retinal microglia. / Li, Zhiwei. / Adviser: Leung Kai Shun. / Source: Dissertation Abstracts International, Volume: 73-02, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 50-66). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

Baicalin, which is a flavonoid, was previously shown to exert neuroprotective effects against ischemic injury and oxidative insults. In this study, baicalin was found to induce neuronal differentiation on both C17.2 NSC and primary mouse NSC originated from hippocampuses of E14.5 mouse embryos. The baicalin-mediated differentiation of C17.2 NSC was noted in dose- and time-dependent manners. Baicalin-treated NSC displayed long processes of neurites. The gene expression of neuronal markers, NF-L, TUBB3 and MAP2 was also significantly increased after treated with 20 to 50 muM baicalin on C17.2 NSC. Treating C17.2 NSC with baicalin significantly increased the number of TUBB3 positive cells by 300%. A significant increase in the gene expression of TUBB3 was also observed on primary NSC upon baicalin treatment at 5 to 10 muM. The number of TUBB3 positive cells was increased by 100% after treating with 10 muM baicalin. C17.2 NSC treated with baicalin also increased the gene expression of GABAergic and serotonergic neuronal subtype specific enzymes GAD1 and TPH1. / Nature provides a vast pool of natural compounds with neuroprotection and neurotrophism. A few of these compounds can induce the differentiation of neural stem cells (NSC). There are ample opportunities to discover more natural compounds with differentiation inducing effect on NSC. One of the objectives of this project is to look for novel natural compounds showing neurogenic effect on NSC. This project has established a platform for screening medicinal materials and natural compounds with neural differentiation promoting effect on C17.2 mouse neural stem cell line. Screening results identified total Sanqi saponins, total Renshen saponins, Huangqin extracts and baicalin as potent candidates for inducing this differentiation of NSC. / This project also aims at characterizing the mechanisms involved in the neuronal differentiation effect of baicalin on NSC. Annotation from microarray analysis indicated that baicalin treatment on C17.2 NSC is related to development of tissue and nervous system. qPCR study attested the increased gene expression of nerve growth factor-beta, neurotrophin-3, pro-neural transcriptional factors Ngn1, Ngn2 and NeuroD2. Western blotting showed that baicalin activated ERK1/2 MAP kinase but not JNK and p38 MAP kinases. / This project demonstrated the neurogenic potential of natural resources on NSC. A novel neuronal induction effect of baicalin on NSC was also demonstrated with its mechanisms characterized. This project also revealed that baicalin can be used for promoting functional recovery of post-ischemia animals. / This study showed for the first time that baicalin exerts neuronal differentiation inducing effect on NSC. Another objective of this project is to study whether baicalin can promote functional recovery of animals with ischemia brain injury. Mice having undergone transient occlusion of the bilateral common carotid arteries with blood-reperfusion to induce global cerebral ischemia were treated with baicalin and/or EGFP-NSC. Ischemia animals received implantation of EGFP-NSC into the caudate putamen and/or intravenous injection of baicalin on alternate days for two-week on day seven post-ischemia displayed significant improvement of the cognitive function in terms of the incident of error and escape time in the water T-maze task compared to the control arm of ischemia mice. Data of the study suggested that the therapeutic effect of baicalin would be comparable to that of neural stem cell transplant in improving the cognitive function in a mouse ischemic stroke model. / Li, Ming. / Adviser: P. C. Shaw. / Source: Dissertation Abstracts International, Volume: 73-01, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 199-232). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

In this study, the brain of senescence accelerated mouse prone 8 (SAMP8) mice model was adopted to investigate PTMs state (especially methylation patterns) of core histones (H2A, H2B, H3 and H4). Seven methylated sites (H3K24, H3K27, H3K36, H3K79, H3R128, H4K20 and H2A R89) were detected by tandem matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF/TOF MS) analysis. The methylation of H3K27 and H3K36 demonstrated a modulating relationship and methylated H3K27 might contribute to the hypermethylation state and gene repression in aged brain. Western blotting results showed that mono-methylated H4K20 decreased during SAMP8 mice aging and di-methylated H3K79 decreased in the brain of 12-month-old SAMP8 mice compared with age-matched senescence accelerated-resistant mouse (SAMR1) control. Di-methylated H3K79 could express in neuron cells of cerebral cortex and hippocampus. Whereas, the number of H3K79 methylation negative cells was higher in the cortex of 12-month old SAMP8 mice than that of age-matched control SAMR1 mice. Chromatin immunoprecipitation (ChIP) result indicated homeodomain transcription factor Pbx1 isoform 1 (Pbx1), transcription factors and transcriptional regulator proteins, such as T-box isoform 20, TetR family precursor BAZ2B and ribosomal protein, were recruited to methylated H3K79 site. Therefore, a model of methylated H3K79 on gene transcriptional regulation was proposed. Furthermore, the consequences of decreased H3K79 methylation in Neuro-2a (N2a) cells were investigated via transfection with Dot1 (disruptor of telomeric silencing) siRNA. After transfection, N2a cells displayed shorter neurite and less dendrite. Proteomic change in the N2a cells provided convincing evidence for the multi-function of decreased H3K79 methylation on transcriptional regulation, protein translation and folding, stress response and DNA breaks repair, which would contribute to brain dysfunction during neurodegenerative disease or aging. / Nowadays, many countries including China are experiencing aging populations. Aging has become the major risk factor for many diseases, such as neurodegenerative disease. The studies on the role of epigenetics in the aging process have grown tremendously in recent years. However, no systematic investigations have provided the information on histone post-translational modifications (PTMs) in aged brain and the roles of histone PTMs in brain aging are still unknown. / This study gave a new insight into the link between histone PTMs and brain aging. It could provide the experimental evidence for future studies and help us to better understand aging or neurodegenerative disease at epigenetic level. Furthermore, it could benefit for setting up the strategies for epigenetic therapy to neurodegenerative disease. / Wang, Chunmei. / Adviser: Ngai Saiming. / Source: Dissertation Abstracts International, Volume: 73-01, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaf 136). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.