INTRODUÇÃO: Sabe-se que a doença periodontal é a doença infecciosa crônica mais prevalente na população adulta, acometendo 1/5 da população em fase ativa de trabalho e causadora de dor. As citocinas e demais substâncias moduladoras da inflamação que promovem e perpetuam a doença periodontal interagem e agravam outras doenças como o diabetes mellitus, aterosclerose e doenças autoimunes. O periodonto, com suas aferências proprioceptivas especializadas, desempenha importante papel de regulação dos movimentos da mastigação. Apesar da região orofacial ter uma ampla área de representação no córtex cerebral não se sabem os efeitos de uma inflamação crônica periodontal nesta representação. Ansiedade e estresse são conhecidos fatores correlacionados à doença periodontal e moduladores de condições dolorosas. Assim, são objetivos deste estudo a avaliação da sensibilidade mecânica em vibrissas, avaliação da ansiedade e o mapeamento do córtex motor de ratos com doença periodontal de 14 e 28 dias de evolução. MÉTODOS: Foram utilizados ratos Wistar machos pesando inicialmente entre 140 e 180 gramas, divididos em 3 grupos principais: grupo controle, grupo sham e grupo de estudo, em que a doença periodontal foi induzida por amarria no primeiro molar inferior direito. Os animais foram avaliados com 14 e 28 dias de doença, sendo a sensibilidade mecânica aferida por filamentos de Von Frey e a ansiedade avaliada por meio do labirinto em cruz elevado. O mapeamento do córtex motor foi realizado por estimulação elétrica epidural de um a dez volts. RESULTADOS: Ambos os períodos de evolução da doença causaram alterações condizentes com doença periodontal. Não houve diferenças no ganho de peso dos animais independente do grupo ao longo do estudo. Nos animais com 28 dias de doença houve maior nocicepção no lado doente com diferença estatística (p=0,042). Os animais do grupo de estudo 14 dias demonstraram mais comportamentos sugestivos de ansiedade nos parâmetros de congelamento (p=0,031), entradas nas extremidades dos braços abertos (p=0,048) e esticamento nos braços abertos (p=0,047) do labirinto em cruz elevado do que os grupos sham e controle. Os animais do grupo de estudo de 28 dias apresentaram maior comportamento de dor e medo observado através da presença do congelamento (p=0,016). O mapeamento do córtex motor evidenciou áreas representativas da mandíbula sobrepostas à área das vibrissas. Foi observada uma expansão da área da mandíbula no grupo da doença periodontal de 14 dias (p=0,038). CONCLUSÃO: A doença periodontal com 14 dias de evolução causou um aumento da resposta motora ipsilateral da mandíbula-mais-vibrissas e alterações de comportamento sugestivas de ansiedade / BACKGROUND: Periodontal disease is the most prevalent chronical infectious disease in adults, affecting 1/5 of people in active phase of labor and causing pain. Cytokines and substances that modulate inflammation promotes and perpetuate de periodontal disease, interacting and worsening other conditions such as diabetes mellitus, aterosclerosis and autoimmune diseases. The periodontium has specialized proprioceptive afferents and plays a role in the regulation of masticatory movements. Despite the wide brain cortical representation area of the orofacial structures, the periodontium has not been described in the literature and the effects of a chronical inflammation in its representation has not been clarified. Anxiety and stress are factors correlated to periodontal disease and modulators of pain. The aim of this study was evaluate vibrissae nociception through mechanical response, anxiety and the motor cortex mapping in rats with periodontal disease after 14 or 28 days of evolution. METHODS: Male Wistar rats (initial weight 140-180 grams) divided into 3 main groups: controls, sham and periodontal disease induced by placement of a cotton ligature in the mandibular right first molar tooth. The evaluations took place after 14 or 28 days of disease. Mechanical response was evaluated by von Frey filaments and anxiety was evaluated through the elevated plus maze. Epidural electrical stimulation (1 to 10 volts) was the method used for the cortical motor mapping. RESULTS: Both evolution periods caused clinical outcomes consistent to periodontal disease. There was no difference in the weight gain of the animals, whatever the group during the study. The animals with 28 days appeared to have a higher nociception in the side affected, with statistical difference (p=0.042). Animals with the disease evolution through 14 days showed more anxious behavior seen by freezing (p=0.031), entries in the extremities of open arms (p=0.048) and stretching in open arms (p=0.047) than the sham and control groups, in the elevated plus maze test. The 28 day disease evolution group showed more pain and fear behavior, seen by freezing (p=0.016). The cortical motor mapping showed an overlapping of jaw and vibrissae areas. There was an expansion of the mandibular area in the 14-day disease group (p=0.038). CONCLUSION: at 14-days, PD led to an expansion of the mandibular-plus-vibrissae motor cortical representation ipsilateral to the disease and behaviors suggestive of anxiety

INTRODUÇÃO: A criocirurgia (crioablação) percutânea em tecidos ósseos próximos da medula espinhal e sistema nervoso periférico tem sido feita na prática clínica, porém sem estudos experimentais que provem sua segurança e eficácia. O objetivo deste trabalho foi desenvolver um modelo experimental suíno in vivo de crioablação vertebral guiada por tomografia computadorizada de feixe cônico (TCFC). Um estudo preliminar de morfometria da coluna vertebral suína por imagens de TCFC foi realizado. Um protocolo específico de crioablação foi criado para adaptar a bola de gelo às dimensões da vértebra suína e testado em modelos in vitro, ex vivo e in vivo. MÉTODOS: O comitê institucional de cuidados com os animais aprovou este estudo. Dezesseis parâmetros anatômicos foram medidos em 36 vértebras lombares suínas e comparados às medidas aferidas nas imagens de TCFC e TC multidetectores (TCMD). Três simuladores in vitro / ex vivo foram desenvolvidos para o posicionamento de sensores de temperatura (termopares) em volta de uma sonda de congelamento. As isotermas foram obtidas durante um protocolo duplo de congelamento-descongelamento de 2-8 minutos. Vinte e duas crioablações vertebrais guiadas por TCFC foram realizadas em oito suínos, mediante termometria e dissecção por dióxido de carbono (CO2) no espaço epidural a fim de proteger os nervos. O seguimento clínico foi realizado até seis dias antes da eutanásia. Os dados clínicos e radiológicos foram correlacionados com o estudo histopatológico à microscopia de luz (n=20) ou eletrônica de transmissão (n=2). RESULTADOS: Na avaliação anatômica da coluna lombar suína a TCFC se mostrou um método de imagem comparável à TCMD e ao estudo anatômico, com correlação significativa (p < 0,05) em todas as variáveis, exceto aquelas que incluiu o tecido cartilaginoso dos planaltos vertebrais. As isotermas registradas foram mais frias no modelo ex vivo imerso em gel (-34 °C e -2 °C; -30 °C e 3 °C; -10 °C e 13 °C, respectivamente), do que nos modelos in vitro (-23 °C e 3 °C; -7 °C e 10 °C; 1 °C e 16 °C) ou ex vivo sem gel (-30 °C e 28 °C). No estudo in vivo, a demonstração das sondas de congelamento no corpo vertebral e do CO2 epidural pelas imagens de TCFC foi bem sucedida em todos os procedimentos. A taxa de complicação maior foi de 4,5%. A distância entre a sonda de congelamento e o canal vertebral (Cp-Sc) foi o parâmetro mais eficiente para categorizar as temperaturas do canal vertebral inferiores a 19 °C à análise do modelo de regressão logística (p < 0,004). Nenhum infiltrado inflamatório perineural foi identificado à microscopia de luz. O suíno cujas vertebras foram submetidas a análise ultraestrutural não apresentou déficit neurológico, embora tenha sido evidenciada a ruptura da bainha de mielina em algumas fibras neurais maiores. CONCLUSÕES: A TCFC foi validada como método de imagens para a análise de vértebras suínas. O modelo ex vivo em gel caracterizou melhor a preservação do frio no tecido ósseo. A combinação de um protocolo específico de congelamento associado a medidas de proteção epidural tornou viável e exequível a crioablação vertebral suína guiada por TCFC. A análise ultraestrutural mostrou modificações precoces das fibras nervosas, sem correlação clínica / INTRODUCTION: Percutaneous spine cryosurgery (cryoablation) close to nerves and spinal cord has been performed in the clinical practice, however without experimental studies proving its safety and efficacy. The aim of this work was to develop an experimental swine model of in vivo cone beam computed tomography (CBCT) guided vertebral cryoablation. A preliminary morphometric study of the porcine spine by CBCT imaging was carried out. A specific cryoablation protocol was proposed to adapt the \"ice ball\" to the swine vertebrae dimensions. Subsequently, the protocol was tested in in vitro, ex vivo and in vivo models. METHODS: The institutional animal care committee approved this study. Sixteen anatomical parameters were measured in 36 lumbar swine vertebrae and compared to the same measurements of the CBCT and multidetector CT (MDCT). Three models of in vitro / ex vivo studies were developed for the positioning of thermocouples around the cryoprobe. Isotherms were obtained from measured temperatures for each minute during a 2-8 minutes double freezing-thawing protocol. Twenty -two CBCT-guided vertebral cryoablations were performed in eight pigs. Epidural thermocouples registered the temperatures while carbon dioxide (CO2) was injected in the epidural space to protect nerves. The clinical follow-up was carried out until six days before euthanasia. Clinical and radiologic data were correlated to the histopathology study with light microscopy (n=20) or electron transmission microscopy (n=2). RESULTS: CBCT was proven to be a comparable imaging method to MDCT with significant correlation (p < 0.05) in all variables, except in those including the cartilaginous tissue of the vertebral plateau. The registered isotherms were colder in the ex vivo model embedded in gel (-34 °C and -2 °C; -30 °C and 3 °C; -10 °C and 13 °C, respectively) than in the in vitro model (-23 °C and 3 °C; -7 °C and 10 °C; 1 °C and 16 °C) or the ex vivo model without gel (-30 °C and 28 °C). In the in vivo study the CBCT imaging was well succeeded to demonstrate the cryoprobes inserted in the vertebral body and the epidural CO2 in all procedures. The major complication rate was 4.5%. The distance between the cryoprobe and the spinal canal (Cp-Sc) was the most efficient parameter to categorize the vertebral canal temperatures below 19 °C in the logistic regression model analysis (p < 0.004). Perineural inflammatory infiltrate was not identified in the light microscopy analysis. One swine did not present neurological deficits, although the ultra-structural analysis has evidenced myelin sheath disruption in some large neural fibers. CONCLUSIONS: The CBCT imaging was validated as an imaging method for the swine vertebrae analysis. The ex vivo model embedded in gel featured better the cold preservation in the bone tissue. The combination of a specific freezing protocol associated with epidural protective measures allowed the feasibility of the CBCT-guided vertebral cryoablation in the swine model. The ultra-structural analysis showed early modifications of the nerve fibers

INTRODUÇÃO: Este estudo tem como objetivo comparar os achados biomecânicos e anatomopatológicos de um modelo animal inédito de tendinopatia do tendão do calcâneo, induzido por injeções seriadas de baixa dose da enzima colagenase bacteriana, com o modelo mais comumente utilizado na literatura, induzido por injeção única de maior dose da enzima, e com os controles. A hipótese é que a utilização de injeções seriadas resultaria em alterações tendíneas mais progressivas e duradouras, similar à doença nos humanos. MÉTODOS: Quarenta e cinco (N=45) coelhos foram randomizados em três diferentes grupos de estudo (A, B e Controles). Animais do Grupo A (n=18) foram submetidos a três injeções seriadas de baixa dose de colagenase (0,1mg), em ambos os tendões do calcâneo, separadas por intervalo de duas semanas. Animais do Grupo B (n=18) foram injetados com dose única de maior dose (0,3mg). Já no Grupo Controle, animais (n=9) foram injetados bilateralmente com três doses seriadas de solução fisiológica 0,9%. Após a última injeção, foi realizada eutanásia do mesmo número de animais dos Grupos A e B (n=6), com 10 semanas (Subgrupos A1 e B1), 12 semanas (Subgrupos A2 e B2) e 16 semanas (Subgrupos A3 e B3). Todos os animais do Grupo controle foram eutanasiados após 16 semanas. Alterações anatomopatológicas, pelo escore de Bonar, e biomecânicas foram comparadas entre os grupos e dentro de cada grupo, para os diferentes momentos de eutanásia. Valores de p < 0,05 foram considerados estatisticamente significativos. RESULTADOS: Após 16 semanas, o escore anatomopatológico de Bonar foi significativamente maior para ambos os Grupos A (11,8±2,28) e B (5,6±2,51), quando comparados aos controles (2±0,76). Os valores para o grupo A também diferiram do Grupo B (p < 0,001). Para os desfechos biomecânicos, os grupos diferiram quanto à área de secção transversa do tendão (p=0,003), módulo de elasticidade (p=0,024), e tensões no limite da elasticidade (p=0,020) e na resistência máxima (p=0,022), com piores resultados encontrados nos animais do Grupo A. Na semana 12, também houve diferença entre os Grupos A e B para o escore anatomopatológico de Bonar (p=0,028) e para a tensão no limite da elasticidade(p=0,013), novamente com piores resultados no Grupo A. Já na 10a semana, foram os coelhos do Grupo B que demonstraram alterações mais pronunciadas quando comparados aos do Grupo A, com diferença significativa no Escore de Bonar (p=0,033), área de secção transversa do tendão (p=0,038), rigidez (p=0,048), módulo de elasticidade (p=0,024), força, tensão, energia e densidade de energia no limite da elasticidade (p=0,008, p=0,020, p=0,047 e p=0,0015, respectivamente) além de força e tensão no limite da resistência máxima (p=0,004 e p=0,008, respectivamente). A comparação dos desfechos dentro de cada grupo, entre os diferentes subgrupos, apresentou diferenças significativas no escore de Bonar em ambos os grupos A (p=0,012) e B (p < 0,001). Parâmetros biomecânicos não diferiram entre os subgrupos do Grupo A. Já os subgrupos do grupo B apresentaram diferenças na área de secção transversa do tendão (p=0,011), módulo de elasticidade (p=0,024), tensão no limite da elasticidade (p=0,023) e da resistência máxima (p=0,031), assim como na a densidade de energia no limite da elasticidade (p=0,017), com resultados mais pronunciados no subgrupo B1. CONCLUSÃO: O modelo animal de tendinopatia do tendão calcâneo induzida por injeções seriadas de colagenase apresentou alterações anatomopatológicas e biomecânicas mais avançadas na 16a semana, de caráter progressivo e duradouro, similar à doença dos humanos. Tal modelo experimental pode representar uma melhor opção na indução da tendinopatia do tendão do calcâneo, possibilitando a realização de estudos promissores no futuro / INTRODUCTION: This study aims to compare the biomechanical and histological findings of a new animal model of Achilles tendinopathy induced by serial low-dose injections of bacterial collagenase with the most commonly used high-dose single injection and to controls. The hypothesis of the study is that consecutive low-dose injections of collagenase would result in more progressive and long-lasting tendinopathic findings, reproducing better the disease in humans. METHODS: Forty-five (N=45) rabbits were randomly divided into three groups (A, B and Control). Animals in Group A (n=18) underwent three serial low-dose (0,1mg) injections of bacterial type I collagenase in both Achilles tendons, separated by a two-week interval. Animals in Group B (n=18) underwent bilateral single high dose injection (0,3mg) of the same enzyme. In the Control Group, animals (n=9) were injected bilaterally with three consecutive doses of saline solution, separated by a two-week interval. Following the last injection, the same number of rabbits from Groups A and B (n=6) were euthanized after 10 weeks (Subgroups A1 and B1), 12 weeks (Subgroups A2 and B2), and 16 weeks (Subgroups A3 and B3). Animals in the Control Group were all euthanized after 16 weeks. Histological findings, using the Bonar tendinopathy score, and biomechanical properties of the Achilles tendons were compared between the groups and inside each the group, in the different time-points of euthanasia. Findings at 16 weeks were considered primary outcomes. P-values < 0,05 were considered significant. RESULTS: After 16 weeks, the Bonar score was significantly increased for both Groups A (11,8±2,28) and B (5,6±2,51), when compared to controls (2±0,76). Group A has also differed from Group B (p < 0,001). Regarding biomechanical findings, groups differed in cross-sectional area of the Achilles tendon (p=0,003), Young\'s modulus (p=0,024), Yield stress (p=0,020) and ultimate tensile strength (p=0,022), with the worst results in animals from Group A. At 12 weeks, comparison between Groups A and B have shown significant differences for Bonar score (p=0,028) and Yield stress (p=0,013), again with worse results in Group A. Conversely, at 10 weeks, rabbits in Group B showed worse results when compared to Group A, with significant differences in the Bonar score (p=0,033), cross sectional area of the tendon (p=0,038), stiffness (p=0,048), Young\'s modulus (p=0,024), Yield tension (0,008), Yield stress (p=0,020), energy Yield (p=0,047), ultimate tension (p=0,004), ultimate stress (p=0,008) and yield strain energy density (p=0,015). The comparison of outcomes inside each group, in the different time-points of follow-up, demonstrated significant differences in the Bonar score for Group A (p=0,012) and Group B (p < 0,001). Regarding biomechanical properties, Group A showed no differences between the subgroups for any of the parameters evaluated. Subgroups in Group B differed for cross-sectional area of the tendon (p=0,011), Young\'s modulus (p=0,024), Yield stress (p=0,023), ultimate stress (p=0,031) and yield strain energy density (p=0,017), with worst results in the earliest follow-up (Subgroup B1). CONCLUSIONS: The animal model of Achilles tendinopathy induced by consecutive injections of collagenase showed worse histological and biomechanical properties after 16 weeks, demonstrating more progressive and long lasting tendinopathic findings, reproducing better the disease in humans. This novel experimental model can represent a better option to induce Achilles tendinopathy, allowing promising future research on the subject

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

Protein kinase A (PKA) is an important enzyme inside the body; it is responsible for phosphorylation of gene regulatory elements and thus regulation of gene expression inside the nucleus. Malfunction of PKA affects transcriptional and translational levels of cell signaling ligands, leading to abnormal activity of various signaling pathways. PKA holoenzyme is composed of two regulatory and two catalytic subunits; four main regulatory subunit isoforms (R1α, R1β, R2α and R2β) and four main catalytic subunit isoforms (Cα, Cβ, Cγ and Prkx) of PKA have been identified. Mutations in these subunits lead to altered total PKA activities and PKAT-I to PKAT-II ratios, leading to diseases both in human and mice. These diseases include Carney Complex (CNC), fibrous dysplasia (FD) and Cushing syndrome. We studied the effect of PKA subunit mutations on intracellular PKA activities, PKAT-I to PKAT-II ratios, and bone and adrenal gland phenotypes in transgenic mouse models. Firstly, we generated whole-body transgenic mice single or double heterozygous for PKA regulatory subunits. Tail vertebral bone lesions including osteosarcomas, osteochondromas and osteochondrosarcomas were found in these mice and we found that mutations in different PKA subunits affect bone lesion formation, new bone generation, and bone organization and mineralization in mouse tail vertebrae. Elevated Cβ subunit expression in Parkar1a+/-Prkar2a+/- and Prkar1a+/-Prkar2b+/-double heterozygous mice leads to a less severe vertebral bone lesion phenotype, an increased osteogenic activity and a better bone regeneration activity. We then studied mice with tissue specific knock out of Prkar1a, the gene coding for type I regulatory subunit, specifically in adrenal cortex (AdKO). AdKO mice developed pituitary-independent Cushing syndrome with increased PKA activity. They also demonstrated increased plasma corticosterone levels resistant to dexamethasone suppression. Dietary treatment of both mice with bone lesions and mice with adrenal lesions with COX2 inhibitor Celecoxib led to partial rescue of phenotypes; this is due to inhibition of the positive feedback loop between PKA signaling and inflamasome pathway at COX2 induction level by Celecoxib. / 蛋白激酶A（PKA）是人體中重要的蛋白酶， 它通過燐酸化基因調控元件來實現對細胞核內基因表達的調節。PKA異常影響細胞內信號傳遞因子的基因轉錄和蛋白翻譯水平，從而導致各細胞信號通路的異常活動。PKA全酶由兩個調節亞基和兩個催化亞基組成，目前已經發現的有四個調節亞基 (R1α, R1β, R2α 和R2β) 以及四個催化亞基(Cα, Cβ, Cγ和Prkx)。發生在這些亞基中的基因突變會改變總的PKA活動水平，PKA-I 和PKA-II的比例，在人類和實驗鼠中引起疾病。這些疾病包括卡尼綜合症 （CNC），骨纖維性發育不良（FD）和庫欣綜合症。我們在轉基因鼠模型中研究PKA亞基突變對細胞中PKA總活性， PKA-I和PKA-II比例的影響，以及由此帶來的骨和腎上腺表型的改變和病變。我們首先製造了有一個或兩個PKA亞基雜合性缺失的全身轉基因鼠。在這些轉基因鼠中，我們發現了包括骨肉瘤，骨軟骨瘤和骨軟骨肉瘤在內的尾椎骨病變。研究發現在不同PKA亞基中的基因變異對實驗鼠尾椎骨病變的發生，新骨的形成和骨的結構和纖維化均有影響。在Prkar1a+/-Prkar2a+/-和Prkar1a+/-Prkar2b+/-實驗鼠中我們發現了較高的Cβ催化亞基表達，這兩個基因型因此具有更輕度的骨病變和更強的骨再生能力。我們繼續研究了在腎上腺中敲除了標記PKA 第一調節亞基的Prkar1a基因的實驗鼠 （AdKO）。AdKO實驗鼠中產生了與垂體無關的庫欣綜合症，並伴隨PKA活性的增加。它們還表現出耐地塞米松抑制的血漿皮質酮水平增加。對骨病變或腎上腺病變的實驗鼠通過飲食進行COX2抑制劑塞來昔布的治療可以部分緩解病變表型。這是由對PKA和炎性體的正反饋機制在COX2誘導步驟的抑制造成的。 / Liu, Sisi. / Thesis Ph.D. Chinese University of Hong Kong 2015. / Includes bibliographical references (leaves 115-130). / Abstracts also in Chinese. / Title from PDF title page (viewed on 09, September, 2016). / Detailed summary in vernacular field only.

<p>Intrauterusna restrikcija rasta (IUGR) se odnosi na stanje u kojem fetus nije u mogućnosti da ostvari svoj genetski potencijal za rast. IUGR je ozbiljan klinički problem i nedavno je povezan sa bolestima odraslog doba kao &scaron;to su hipertenzija, insulin nezavistan diabetes melitus, dislipidemije i ishemijske bolesti srca. Eritropoetin je glavni regulator proliferacije i diferencijacije eritroidnih progenitorskih ćelija zahvaljujući svojoj antiapoptotičkoj aktivnosti. Cilj istraživanja je bio da se ispita uticaj IUGR na bubrege, kao i uticaj eritropotina na bubrege sa IUGR. Eksperimentalna studija je sprovedena u gajili&scaron;tu Pasterovog zavoda u Novom Sadu na 60 mi&scaron;eva rase NMRI. IUGR je izazivana aplikacijom deksametazona gravidnim ženkama. Po rođenju su mladunci bili podeljeni u sedam grupa. Mladuncima je u 1. i 7. danu života davan darbepoetin alfa (DA) u dozama od 1, 4 i 10&mu;g/kg. Dve grupe su predstavljale potomke majki koje su tokom trudnoće dobile DA. Nakon 4 nedelje su uzimani uzorci bubrega i vr&scaron;ena je morfolo&scaron;ka i stereolo&scaron;ka analiza glomerula. Aplikacija deksametazona (100 &mu;g/kg) trudnim mi&scaron;icama dovodi do potomstva sa IUGR. Primena DA kod novorođenih mi&scaron;eva sa IUGR dovodi do bržeg porasta telesne mase u prvih 7 dana života (&bdquo;catch-up― rasta). Mi&scaron;evi rođeni sa IUGR imaju manju povr&scaron;inu glomerula bubrega. Primena DA nakon rođenja i u 7. danu života (4 i 10 &mu;g/kg) kod novorođenih mi&scaron;eva sa IUGR dovodi do hipertrofije glomerula bubrega. IUGR nema uticaja na broj glomerula bubrega mi&scaron;eva. Primena DA nema uticaja na broj glomerula bubrega mi&scaron;eva. Mi&scaron;evi rođeni sa IUGR imaju manju debljinu korteksa bubrega. Primena DA (4 i 10 &mu;g/kg) kod mi&scaron;eva rođenih sa IUGR dovodi do povećanja debljine korteksa bubrega. Davanje DA kod IUGR značajno povećava povr&scaron;inu glomerula i debljinu korteksa bubrega.</p> / <p>Intrauterine growth restriction (IUGR) refers to a condition in which a foetus is not able to achieve its genetic potential for growth. IUGR is a serious clinical problem, and has recently been linked with diseases of adulthood, such as hypertension, insulin-independent diabetes mellitus, dyslipidemia, and ischemic heart disease. Erythropoietin is the major regulator of proliferation and differentiation of erythroid progenitor cells, thanks to its anti-apoptotic activities. The aim of this study was to investigate the effect of IUGR on the kidneys, and the impact of erythropoietin on the kidneys with IUGR. The experimental study was conducted in Pasteur Institute of Novi Sad on 60 mice of NMRI race. IUGR has been imposed with the application of dexamethasone to pregnant females. After birth, the pups were divided into seven groups. DA was administered to the pups on the 1st and 7th day of life (dose 1, 4 and 10 &mu;g/kg). Two groups represented the offspring of the mothers who during pregnancy received DA. After 4 weeks, kidney samples were taken and morphological and stereological analysis of the glomeruli was performed. The application of dexamethasone (100 &mu;g/kg) to pregnant mice leads to their offspring with IUGR. Application of DA to newborn mice with IUGR leads to faster weight gain in the first 7 days of life (&quot;catch-up&quot; growth). Mice born with IUGR have a reduced glomerular surface. Application of DA after birth and on the 7th day of life (4 and 10 &mu;g/kg) in mice with IUGR leads to hypertrophy of the kidney glomeruli. IUGR has no effect on the number of kidney glomeruli. Application of DA has no effect on the number of kidney glomeruli. Mice born with IUGR have a reduced cortical thickness. Application of DA (4 and 10 &mu;g/kg) in mice born with IUGR leads to increased thickness of the kidney cortex. Application of DA to mice with IUGR significantly increases the surface area of the kidney glomeruli and cortical thickness.</p>

INTRODUÇÃO: O transplante hepático é o único tratamento efetivo para uma variedade de doenças hepáticas irreversíveis. No entanto, o número limitado de doadores pediátricos leva ao uso de enxertos hepáticos de doadores adultos, com necessidade de anastomoses vasculares mais complexas. Essas anastomoses tornam-se complicadas pela diferença no calibre dos vasos entre o doador e o receptor, resultando em alterações do fluxo sanguíneo, estenose da anastomose venosa ou arterial e trombose. Os efeitos para regeneração hepática decorrentes da privação do fluxo sanguíneo pela veia porta ou pela artéria hepática não estão completamente elucidados. Experimentalmente, quando um lobo do fígado não recebe o fluxo venoso portal, é observada atrofia deste segmento e hipertrofia do restante do órgão perfundido. Embora existam vários modelos experimentais para estudo da regeneração hepática, poucos são focados em animais em crescimento. Além disso, os efeitos regenerativos de drogas como o tacrolimus e a insulina precisam ser pesquisados, com o objetivo de encontrar um tratamento ideal para a insuficiência hepática ou um método de estimular a regeneração do fígado após ressecções ou transplantes parciais. O objetivo do presente estudo é descrever modelos de regeneração hepática em ratos em crescimento com: 1) ausência de fluxo hepático arterial e 2) redução do fluxo portal. Adicionalmente, o estudo avalia o efeito pró-regenerativo do tacrolimus e da insulina nesses modelos descritos. MÉTODOS: cento e vinte ratos (entre 50 e 100g de peso) foram divididos em 6 grupos, de acordo com o tipo de intervenção cirúrgica: Grupo 1, incisão abdominal sem intervenção hepática; Grupo 2, hepatectomia a 70%; Grupo 3, hepatectomia a 70% + estenose de veia porta; Grupo 4, hepatectomia a 70% + ligadura da artéria hepática; Grupo 5, hepatectomia a 70% + estenose de veia porta + insulina; Grupo 6, hepatectomia a 70% + estenose de veia porta + tacrolimus. Os animais dos grupos 1 ao 4 foram subdivididos em 5 subgrupos de acordo com o momento da morte: 1, 2, 3, 5 e 10 dias após a intervenção cirúrgica. Os animais dos grupos 5 e 6 foram subdividos em 2 subgrupos de acordo com o momento da morte: 2 e 10 dias após a intervenção cirúrgica. Os lobos hepáticos remanescentes foram submetidos à análise histomorfométrica, imuno-histoquímica e molecular. RESULTADOS: Verificou-se que no grupo com hepatectomia a 70% houve recuperação do peso do fígado no terceiro dia com aumento da atividade mitótica, enquanto que no grupo com estenose portal não se observou esse fenômeno (p < 0,001). A insulina e o tacrolimus promoveram aumento do peso do fígado e do índice mitótico. A atividade mitótica foi considerada aumentada nos animais dos grupos hepatectomia, hepatectomia + ligadura da artéria, insulina e tacrolimus; e esse parâmetro estava reduzido no grupo submetido à hepatectomia + estenose portal (p < 0,001). A expressão de interleucina 6 estava presente em todos os animais, sendo significativamente maior nos grupos hepatectomia, hepatectomia + ligadura da artéria e significativamente menor no grupo hepatectomia + estenose portal. Entretanto, a administração de tacrolimus ou insulina recuperou os níveis teciduais de interleucina 6 no grupo com estenose portal. CONCLUSÕES: No presente estudo foi padronizado um modelo simples e facilmente reprodutível para estudar a regeneração hepática em ratos em crescimento com redução do fluxo arterial ou venoso para o fígado. Foi demonstrado que a administração de insulina ou tacrolimus é capaz de reverter os efeitos deletérios da estenose portal na regeneração hepática. A obstrução do fluxo arterial não afetou a capacidade regenerativa hepática / BACKGROUND/PURPOSE: Liver transplantation is an effective treatment for a variety of irreversible liver diseases. However, the limited number of pediatric donor livers leads to the use of adult livers, which usually require more complex vascular anastomoses. These anastomoses are complicated by differences in vessel caliber between donors and recipients, resulting in vascular flow anomalies, stenosis of the venous or arterial anastomosis and thrombosis . The effects of portal vein or hepatic arterial flow privation in hepatic regeneration have not been completely elucidated. Experimentally, when a liver lobe is deprived of portal vein flow, atrophy is observed with hypertrophy of the other perfused parts of the organ, and interleukin-6 (IL-6) is required for normal liver regeneration. Although several experimental models are currently used to study the liver regeneration mechanisms, few studies have focused on the growing animal. In addition, the regenerative effects of drugs (e.g., tacrolimus and insulin) have been experimentally studied, aiming to find an ideal treatment for hepatic failure or a method of stimulating liver regeneration after extensive resection or partial transplants. The aim of the present investigation was to describe the new models of liver regeneration in growing rats with: 1) absence of arterial blood hepatic inflow and 2) reduced portal flow. Additionally, it was studied whether tacrolimus or insulin could have any pro-regenerative effect under such conditions. METHODS/MATERIALS: one hundred and twenty rats (50-100 g body weight) were divided into 6 groups based on the intervention type: Group 1 (sham), abdominal incision without intervention; Group 2, 70% hepatectomy; Group 3, 70% hepatectomy + portal vein stenosis; Group 4, 70% hepatectomy + ligation of the hepatic artery; Group 5, 70% hepatectomy + portal vein stenosis + insulin; and Group 6, 70% hepatectomy + portal vein stenosis + tacrolimus. Animals in groups 1 to 4 were subdivided into 5 groups according to the moment of death: 1, 2, 3, 5 and 10 days after surgical intervention. The animals in groups 5 and 6 were subdivided into 2 other groups according to the moment of death: 2 and 10 days after surgical intervention. The remnant liver lobes were harvested for morphological, histological histomorphometric, immunohistochemical and molecular analyses. RESULTS: it was verified that the hepatectomy group regained liver weight on the third day and had increased mitotic activity, and the portal vein stenosis prevented these phenomena, as well as the increased mitotic index (P < 0.001). In addition, insulin and tacrolimus promoted a significant increase of liver weight. Mitotic activity was considerably increased in the hepatectomy, hepatectomy + arterial ligature, insulin and tacrolimus groups and this parameter was reduced by portal vein stenosis. The expression of the interleukin-6 (IL-6) gene was present in all the animal groups. Tissue levels of IL- 6 were significantly increased by hepatectomy and hepatectomy + hepatic artery ligature; portal vein stenosis prevented this change. However, the administration of tacrolimus or insulin could recuperate the tissue levels of IL-6. CONCLUSION: In the present study a simple and highly reproducible model was standardized to study liver regeneration with portal vein or hepatic artery blood inflow reduction in growing rats. It was demonstrated that insulin or tacrolimus administration may partially reverse the harmful effects of portal vein stenosis. The obstruction of the arterial flow did not affect liver regeneration

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.