Attention-deficit hyperactivity disorder (ADHD) is a common neuropsychiatric disorder with onset at preschool age Approximately 5-10% of school-aged children worldwide have ADHD. Psychostimulants are the most common treatments for ADHD, although the precise etiology and pathological mechanisms underlying ADHD are poorly understood. Animal models could help to elucidate and further the understanding of this disorder. Among the major rodent models of ADHD of the genetic and neurotoxin-exposed animal models, the spontaneously hypertensive rats (SHR) are more extensively studied. Nevertheless, the mechanism of ADHD is complex and the evidence of SHR model for ADHD has been conflicting. Objective. In this work, we combined behavioral, neurochemical, neuroimaging, pharmacological and molecular studies to examine SHR as an animal model of ADHD. At the same time, the results of our studies could help us to explore the potential mechanism of ADHD. Material and methods. We compared the locomotor activity, attention, inhibition, learning and memory of juvenile male SHR with those of age- and gender-matched genetic control Wistar-Kyoto rats (WKY) by using the open field test, Morris water maze and prepulse inhibition test. We employed magnetic resonance imaging (MRI) to measure potential morphological differences between different brain areas of SHR and WKY, and the functional MRI (fMRI) for functional differences in these brain areas. We also measured dopamine concentration and dopamine related genes expression in the different dopamine pathways by using enzyme-linked immunosorbent assay (ELISA) to measure the dopamine concentration and by using real time PCR to assay genes expression. We examined SHR responses to D-amphetamine (D-AMP), which is psychostimulant. These included locomotor activity and inhibition ability during D-AMP treatment, expression of dopamine related genes after D-AMP treatment measured by real time PCR and c-fos protein after repeated treatment of D-AMP by the Western Blotting. Results . Hyperactivity, impulsivity and attention deficit were observed in SHR. Decreased brain volume in caudate-putamen and vermis cerebelli in SHR were demarcated using MRI. Functional MRI (fMRI) and altered c-fos expression indicated plasticity changes of the prefrontal cortex (PFC) in SHR. Dopamine content was found to decrease in mesocortical and mesolimbic dopamine pathways, but increased in the striatum. Dopamine D4 receptors gene and protein expression were decreased in the PFC in SHR. We also found that the expression of the synaptosomal-associated protein 25 (SNAP-25) gene was initially lower in the PFC but higher in the striatum in SHR. However, this disparity of SNAP-25 in the PFC vanished after repeated treatment of D-AMP between SHR and WKY. Conclusions. In the present study, we demonstrated that SHR could be established as an ADHD model by completing complex assessments of face validity, construct validity and prediction validity. We suggested that the "synaptogenesis hypotheses" might contribute to the abnormal release of dopamine and dysfunction of PFC and the striatum in SEER. In conclusion, our results have provided further new information relevant to the understanding of ADHD in human via the analysis of the SHR model. / Li, Qi. / Adviser: David Yen. / Source: Dissertation Abstracts International, Volume: 69-02, Section: B, page: 1375. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (leaves 108-125). / 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, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese. / School code: 1307.

Existe uma grande preocupação com relação aos efeitos a longo prazo que muitos poluentes químicos possam ter sobre a saúde e o ambiente. Tal é o número de diferentes poluentes e a complexidade de suas interações que seus efeitos não podem ser prontamente definidos em programas de monitoramento que determinam a presença de poluentes no ambiente. Recentemente, pesquisas identificaram um grupo de enzimas conhecidas coletivamente como proteínas antioxidantes, que são induzidas em resposta aos poluentes, como os metais pesados e parecem proteger as células contra os possíveis danos causados por estes agentes. É possível que a análise da indução e acumulação de proteínas antioxidantes e/ou de defesa, possa fornecer um sistema biológico versátil de monitoramento dos efeitos da poluição. E assim, o estudo da atividade enzimática poderá vir a se configurar como um critério de avaliação da fitotoxicidade de metais pesados em plantas. Com esse propósito, foi desenvolvido um trabalho com o objetivo de estudar as alterações de crescimento e bioquímicas causadas pelo efeito do Cádmio (Cd) em arroz. Experimentos foram montados utilizando 8 diferentes genótipos de arroz da espécie Oryza sativa: F222, IAC202, Caipó, J199, IAC165, J79, F133, F35 e mais duas espécies: Arg2 (Oryza latifolia) e Oryza glumaepapulo nos quais foram submetidas a diferentes concentrações de Cd em solução nutritiva (0mM, 0,05mM, 0,5mM) durante um período de 3 e 7 dias para avaliação do efeito desse metal pesado no comprimento do sistema radicular. Foi realizado um segundo ensaio utilizando a cultivar IAC165, submetida a diferentes concentrações de CdCl2 (0mM, 0,01mM, 1,0mM). Nestas concentrações, coletas de folhas e raízes foram feitas em períodos de tratamentos constituídos de 0, 3, 6, 9, 12, 15, 18, 21, 24, 30, 36, 42, 48, 54, 60, 66, 72horas. Com relação ao crescimento radicular do 1° ensaio foram identificados três padrões de resposta: um primeiro, cuja resposta à menor dosagem (0,05 mM de CdCl2) é significativa e esta se mantém na dosagem seguinte (0,5 mM); um segundo, onde também é significativa a resposta à menor dosagem, mas esta se intensifica significativamente com o aumento da dosagem e um terceiro, no qual as linhagens mostraram-se resistentes às dosagens testadas, não sendo afetadas em seu padrão de crescimento de raízes no tempo desse estudo. O parâmetro bioquímico analisado no 2° ensaio foi relativo aos níveis de atividade de enzimas antioxidantes, como Catalase e Glutationa Redutase. que mostraram padrões semelhantes de resposta tanto para Catalase como para Glutationa Redutase, observando-se elevação das atividades dessas enzimas antioxidantes em folhas e raízes, sendo o aumento de atividade da Glutationa Redutase nas raízes altamente significativo, sugerindo que a síntese de Glutationa reduzida possa estar estimulada para subseqüente síntese de fitoquelatinas. / The response of a group of rice genotypes to cadmium exposure was tested using the root growth as a parameter during the time length of the treatment. Three distinct response patterns were identified: a significant initial (0.01 mM) dosage effect, which was maintained with the increase of CdCl2 concentration to 1 mM; a significant initial effect, which was intensified with the increase of CdCl2 concentration, and a group of varieties resistant ot the CdCl2 concentration tested. Significant interactions between dosage and varieties were observed. Enzymatic assays for catalase and gluthatione reductase were also carried out for in plants exposed to CdCl2. Similar response patterns for both enzymes were observed. The activities of catalase and gluthatione reductase in leaves and roots were increased and in the case of gluthatione reductase in roots, such an increase was highly significant, suggesting that the synthesis of reduced gluthatione may be stimulated for subsequent synthesis of phytochelatins.

Ao longo dos processos de imortalização e transformação maligna, as células adquirem inúmeras alterações genéticas, que são causadas por fatores endógenos e exógenos como agentes biológicos e a geração de espécies reativas de oxigênio. Neste trabalho, uma linhagem celular espontaneamente transformada foi clonada a partir de explantes de embriões de camundongos C57bl/6. Esta linhagem mostrou-se produtora de pigmento escuro; a análise citoquímica e ultraestrutural permitiu caracterizar a linhagem como tendo origem melanocítica. A linhagem, denominada Mgal3, mostrou-se tumorigênica quando implantada no tecido subcutâneo de animais singenéicos, apresentando capacidade de disseminação linfática, dando origem a metástases em linfonodos, o que permitiu caracteriza-la como uma linhagem de melanoma murino. O processo de transformação deste melanoma caracterizou-se pela expressão de genes retrovirais endógenos, com expressão do antígeno associado a melanoma (MAA), reconhecido pelo anticorpo monoclonal MM2-9B6; ausência de mutações nos exons 5 a 8 do gene supressor de tumor TP53; e, silenciamento do gene CDKN2a, que codifica duas proteínas que atuam em redes de supressão de tumores, p16INK4a e p19ARF. A perda de expressão de pelo menos um destes produtos gênicos parece associada a mecanismos epigenéticos, uma vez que o tratamento de Mgal3 com o inibidor de DNA metiltransferase 5-Aza-2-deoxicitidina, restaurou a transcrição de pelo menos um dos transcritos do gene CDKN2a. Da mesma forma, observamos que o gene LGALS3, que codifica a lectina animal galectina-3 também é silenciado nesta linhagem, mostrando que esta molécula não está associada à manutenção desta célula transformada em condições de cultivo. / A novel murine melanoma cell line named Mgal3 was generated from embryo explants. This cell line gave rise to metastatic tumors when injected subcutaneously in C57bl/6 mice. Tumor histogenesis was determined at the cytochemical (Fontana Masson staining), immunohistochemical (staining with anti-HMB45 and anti-S100) and ultrastructural levels. Mgal3 produces high amounts of retroviral C particles and was recognized by the mAb MM2-9B6, which reacts with a melanoma associated antigen derived from the envelope of the ecotropic retrovirus MelArv. No mutations were found in TP53 exons 5-8, however loss of CDKN2a expression was observed. Treatment of Mgal3 with the demethylating agent azadeoxycytidine indicated that at least one of the genes encoded at the CDKN2a locus was silenced by promoter hypermethylation. Furthermore, this cell line did not express the animal lectin, galectin-3. The galectin-3 gene promoter seemed to be hypermethylated, since treatment of Mgal3 with azadeoxycytidine led to the de novo expression of the lectin.

Retinopathy of prematurity, a disease characterised by aberrant retinal vascular development in premature neonates, is a leading cause of blindness and visual impairment in childhood. This work sought to examine differences in the susceptibility of inbred rat strains to oxygen-induced retinopathy, a model of human retinopathy of prematurity. The overriding aim was to identify genetic factors in rats that might be generalisable to humans. Newborn rats of six different strains were exposed to alternating cycles of hyperoxia and relative hypoxia for fourteen days. Rats were removed to room air and killed for analysis immediately, to assess oxygen-induced retinal vascular attenuation, or four days later to evaluate the extent of hypoxia-induced vasoproliferation. Whole flat-mounted retinae were stained with fluorophore conjugated isolectin GS-IB4, and measurement of vascular area was conducted using fluorescence microscopy and video-image analysis. A hierarchy of susceptibility to the inhibitory effects of cyclic hyperoxia and relative hypoxia on postnatal retinal vascularization was identified for the rat strains studied. Susceptibility to vascular attenuation was predictive of the subsequent risk of vascular morphological abnormalities. Cross-breeding experiments between susceptible and resistant strains demonstrated that the susceptible phenotype was dominantly inherited in an autosomal fashion. These studies confirmed an association between ocular pigmentation and retinopathy risk, however the finding of differential susceptibility amongst albino rat strains implicated factors in addition to those associated with ocular pigmentation. Quantitative real-time reverse transcription-polymerase chain reaction was used to compare the retinal expression of angiogenic factor genes in susceptible and resistant strains with the aim of identifying a genetic basis for the strain difference. Eight angiogenic factor genes were selected for study: vascular endothelial growth factor (VEGF); VEGF receptor 2; angiopoietin 2; Tie2; pigment epithelium-derived factor; erythropoietin; cyclooxygenase-2 and insulin-like growth factor-1. The most notable difference between strains was the expression of vascular endothelial growth factor (VEGF) during the cyclic hyperoxia exposure period - higher VEGF expression was associated with relative resistance to retinopathy. Other differences in retinal angiogenic factor gene expression between strains, such as higher expression of VEGF receptor 2 and angiopoietin 2 in resistant strains, appeared to be secondary to those in VEGF. Following cyclic hyperoxia, the expression pattern of angiogenic factor genes changed - messenger RNA levels of hypoxia-induced genes, including VEGF, VEGF receptor 2, angiopoietin 2 and erythropoietin, were significantly higher in those strains with larger avascular areas, than in those strains that were relatively resistant to retinopathy. These findings provide firm evidence for hereditary risk factors for oxygen-induced retinopathy in the rat. Differences in the regulatory effects of oxygen on VEGF expression appear to be central to the risk of retinopathy. The potential relevance of these hereditary factors is discussed in the context of the human disease.

Thesis (Ph. D.)--University of Missouri--Columbia, 2003. / Typescript. Vita. Includes bibliographical references (leaves 146-172). Also available on the Internet.

The control of cellular tyrosine phosphorylation levels is of great importance in many biological systems. Among the kinases and phosphatases that modulate these levels, the LAR-RPTPs have been suggested to act in several key aspects of neural development, and in a dysfunctional manner in various pathologies from diabetes to cancer. The aim of this thesis is to describe the physiological functions of one of the members of this subfamily of RPTPs, namely RPTPsigma. First, we showed that glucose homeostasis is altered in RPTPsigma null mice. They are hypoglycemic and more sensitive to exogenous insulin and we proposed that the insulin hypersensitivity observed in RPTPsigma-null mice is likely secondary to their neuroendocrine dysplasia and GH/IGF-1 deficiency. In addition to regulating nervous system development, RPTPsigma was previously shown to regulate axonal regeneration after injury. In the absence of RPTPsigma, axonal regeneration in the sciatic, facial and optical nerves was enhanced following nerve crush. However, myelin-associated growth inhibitory proteins and components of the glial scar such as CSPGs (chondroitin sulfate proteoglycans) have long been known to inhibit axonal regeneration in the CNS, making spinal cord injury irreversible. In collaboration with Dr Samuel David, we unveiled that RPTPsigma null mice are able to regenerate their corticospinal tract following spinal cord hemisections as opposed to their WT littermates. We then isolated primary neurons from both sets of animals and found that the absence of RPTPsigma promotes the ability of the neurons to adhere to certain inhibitory substrates. Finally, in order to better understand the physiological role of RPTPsigma, we used a yeast substrate-trapping approach, to screen a murine embryonic library for new substrates. This screen identified the RhoGAP p250GAP as a new substrate, suggesting a downstream role for RPTPsigma in RhoGTPase signaling. We also identified p130Cas and Fyn as new binding partners. All these proteins have clear functional links to neurite extension. The characterization of RPTPsigma and its signaling partners is essential for understanding its role in neurological development and may one day translate into treatments of neural diseases and injuries.

Decorin, is an extracellular matrix proteoglycan with important biological functions. Decorin deficiency affects collagen fibrillogenesis, airway mechanics, airway-parenchymal interdependence, and airway smooth muscle proliferation and apoptosis. We questioned whether decorin deficiency would alter allergen-induced asthma in a mouse model. Decorin-/- and decorin+/+ mice (C57Bl/6) were sensitized and challenged with ovalbumin. Control animals received saline. Responsiveness was assessed at baseline and after delivery of increasing concentrations of methacholine. Histological analyses were also performed. Decorin deficiency resulted in more modest hyperresponsiveness. Respiratory resistance and elastance along with tissue damping and tissue elastance, were increased in ovalbumin decorin +/+ and decorin-/-, but more so in decorin+/+ . Airway resistance was increased in ovalbumin decorin+/+ only. Inflammation and collagen staining within the airway wall, were increased in ovalbumin decorin+/+ mice only; whereas biglycan was significantly increased in ovalbumin decorin-/- mice only. These results reflect the role of decorin in the development of allergen-induced asthma.

Hypertension is the number one cause of death worldwide. Low-grade inflammation has been identified as one of the mechanisms contributing to blood pressure elevation and remodeling of the vasculature in hypertension. Mechanisms involved in vascular inflammation and hypertension remain elusive. Vasoactive peptides such as endothelin-1 (ET-1) and angiotensin II (Ang II), oxidative stress and infiltration of immune cells are increased in cardiovascular tissues of hypertensive individuals. Since the vasculature is a major regulator of blood pressure levels, the hypothesis has been proposed that vascular inflammatory responses contribute to development of hypertension. / Objectives of this thesis were 1) to investigate the role of T cells in development of vascular inflammation observed in genetically hypertensive rats, 2) to identify vascular sources of reactive oxygen species production in mineralocorticoid-induced hypertension and 3) to study the effect of peroxisome proliferator-activated receptor (PPAR)-gamma activators on vascular pro-inflammatory signaling pathways in Ang II-induced hypertension. / The first study that is part of this thesis shows that the transfer of chromosome 2 from normotensive to hypertensive rats reduces plasma levels of pro-inflammatory cytokines, expression of adhesion molecules and infiltration of T cells in aorta as well as resulting in lower blood pressure levels. These effects are accompanied by increased regulatory T cell mediators. We discovered that regulatory T cells are regulated by chromosome 2 and may be responsible for reducing inflammatory responses in hypertensive rats. / The second study of this thesis demonstrates in DOCA-salt hypertensive rats that superoxide (·O2-) production originates in part from xanthine oxidase activity induced by the ET-1 system and from mitochondrial sources, particularly complex II of the respiratory chain. We thus have uncovered two sources of reactive oxygen species (ROS) that can stimulate inflammatory responses in hypertension, since vascular ·O 2- production in this model was shown to induce vascular inflammation. / The third study of the thesis shows that activators of PPAR-gamma reduce blood pressure levels and signaling pathways including Akt/PKB, SHIP2, ERK1/2, 4E-BP1 in aorta and resistance arteries in Ang II-induced hypertension. PPARy acts as an anti-inflammatory transcription factor, and the present study suggests that Ang II down-regulates PPAR-gamma activity to exert its pro-inflammatory effects. / In conclusion, by targeting inflammatory mediators, it may be possible to reduce blood pressure levels in hypertensive animals. This suggests that inflammatory responses may play a crucial role in development of high blood pressure.

Recent population studies provide evidence that individuals with high circulating insulin levels have a poor prognosis and/or increased risk of cancer development; however, laboratory studies concerning the role of insulin in breast cancer biology are sparse. We compared the growth of 4T1 murine breast cancer allografts in control mice, alloxan-induced hypoinsulinemic mice, and mice treated with the insulin/insulin-like growth factor-1 receptor tyrosine kinase inhibitor BMS-536924. Both interventions significantly decreased tumor growth versus control and decreased pathway activation downstream of the insulin receptor as reflected by Aktser473 phosphorylation status in the neoplastic tissue. Alloxan-treated mice exhibited signs of insulin deficiency, while BMS-536924-treated animals showed only minor metabolic derangements. Skeletal muscle displayed reduced pAktser473 in alloxan-treated mice. In contrast, BMS-536924 treatment increased pAktser473 in muscle. This raises the possibility that the relative lack of metabolic toxicity of BMS-536924 involves varying tissue levels of the drug. These results support the view that host insulin physiology is a potentially modifiable determinant of breast cancer behaviour.

Dissertation (Ph.D.)--University of South Florida, 2007. / Title from PDF of title page. Document formatted into pages; contains 90 pages. Includes vita. Includes bibliographical references.