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Patients with macular degeneration (MD) often fixate with a preferred retinal locus (PRL). Eye movements made while fixating with the PRL (in MD patients) has been observed to be maladaptive compared to those made while fixating with the fovea (normal sighted individuals). For example, in MD patients, PRL eye movements negatively affect fixation stability and re-fixation precision; consequently creating difficulty in reading and limits to their execution of other everyday activities. Abnormal eye movements from the PRL affect research on the physiological adaptations to MD. Specifically, previous research on cortical reorganization using functional magnetic resonance imaging (fMRI), indicates a critical need to accurately determine a MD patient's point of gaze in order to better infer existence of cortical reorganization. Unfortunately, standard MR compatible hardware eye-tracking systems do not work well with these patients. Their reduction in fixation stability often overwhelms the tracking algorithms used by these systems. This research investigates the use of an existing magnetic resonance imaging (MRI) based technique called Predictive Eye Estimation Regression (PEER) to determine the point of gaze of MD patients and thus control for fixation instability. PEER makes use of the fluctuations in the MR signal caused by eye movements to identify position of gaze. Engineering adaptations such as temporal resolution and brain coverage were applied to tailor PEER to MD patients. Also participants were evaluated on different fixation protocols and the results compared to that of the micro-perimeter MP-1 to test the efficacy of PEER. The fixation stability results obtained from PEER were similar to that obtained from the eye tracking results of the micro-perimeter MP-1. However, PEER's point of gaze estimations was different from the MP-1's in the fixation tests. The difference in this result cannot be concluded to be specific to PEER. In order to resolve this issue, advancements to PEER by the inclusion of an eye tracker in the scanner to run concurrently with PEER could provide more evidence of PEER's reliability. In addition, increasing the diversity of AMD patients in terms of the different scotoma types will help provide a better estimate of PEER flexibility and robustness.

Sensory deprivation in one modality can enhance the development of the remaining modalities via mechanisms of synaptic plasticity. Mice of C3H strain suffers from RD1 retinal degeneration that leads to visual impairment at weaning age. Independently on the retinal degeneration there is also present olivocerebellar degeneration caused by Lurcher mutation. This neurodegenerative disorder causes motor deficits, increased CNS excitability as well as changes in synaptic plasticity. The aim of this study was to evaluate a role of whiskers in compensation of the visual deficit and to assess the influence of the olivocerebellar degeneration on this process. To differentiate contribution of the whiskers from other mechanisms that can take part in the compensation, we investigated the effect of both chronic and acute tactile deprivation. We focused on motor skills (rotarod, beam walking test), gait control (CatWalk system), spontaneous motor activity (open field) and the CNS excitability (audiogenic epilepsy). In the seeing mice without olivocerebellar degeneration, the removal of the whiskers had no effect. In the blind animals without olivocerebellar degeneration, chronic tactile deprivation caused changes in gait and impaired the performance in motor tests. Some other compensatory mechanisms were involved but the...

Made available in DSpace on 2015-07-22T20:49:32Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-04-28 / O objetivo deste trabalho é avaliar as anormalidades da esclera, coroide e retina de coelhos induzidas pela dieta hipercolesterolêmica, além da possibilidade de prevenção dessas anormalidades com administração sistêmica de rosiglitazona. Para isto, 54 coelhos new zealand foram distribuídos em quatro grupos: grupo-controle (GC) recebeu dieta normal; grupo 1 recebeu dieta hipercolesterolêmica; grupo 2 recebeu dieta hipercolesterolêmica associada à administração diária de 3 mg de rosiglitazona a partir do 14º dia do início do experimento; e grupo 3 recebeu dieta hipercolesterolêmica associada à administração diária de 3 mg de rosiglitazona desde o início do experimento. Os coelhos foram pesados e submetidos à dosagem sérica de colesterol total, triglicerídeos, high density lipoprotein (HDL) colesterol e glicemia de jejum no início do experimento, no 14º dia e no momento da eutanásia (42º dia). A esclera e coroide foram submetidas à análise histológica e histomorfométrica. A retina foi submetida à análise imuno-histoquímica com o anticorpo monoclonal anticalretinina (CR) e anticorpo anti-glial fibrillary acidic protein (GFAP). Quando positivo para o marcador anticalretinina, duas análises quantitativas foram realizadas. Na primeira, foram contadas todas as células ganglionares imunorreativas. Na segunda, todas as células e elementos celulares imunorreativos foram avaliados pelo exame de morfometria de cores. Os dados foram analisados pelo teste nãoparamétrico de Kruskal-Wallis e teste de Shapiro-Wilks-Testand. Valores abaixo de 0,05 foram considerados estatisticamente significantes. Os resultados referentes ao peso demonstraram significativo aumento nos grupos 1 e 3 em relação ao GC no 14º dia (p<0,009), enquanto no 42º dia os grupos 1, 2 e 3 apresentaram representativamente mais peso que o GC (p<0,023). Quanto às variáveis laboratoriais, destacaram-se o aumento significativo da glicose e colesterol total de G1 em relação ao controle (p<0,001), assim como o acentuado aumento da HDL no G3 em relação aos demais grupos (p<0,001), no 14º dia. A HDL manteve-se expressivamente elevada no G3 em relação aos demais grupos no momento da eutanásia (p<0,001). À análise histomorfométrica da esclera e coroide obteve-se normalidade do GC. Por outro lado, o G1 mostrou marcante aumento da espessura da esclera e coroide em relação ao GC (p=0,008), enquanto que no G3 houve espessamento de esclera e coroide menor que no G1 (p=0,048). Elevado número de histiócitos foi observado na parede escleral do grupo submetido à dieta hipercolesterolêmica (G1), seguido de forma decrescente por G2, G3 e GC. A análise imuno-histoquímica da retina com o anticorpo monoclonal anticalretinina ressaltou número mais alto de células ganglionares imunorreativas no G1 que no G3 (p=0,002). O exame de morfometria de cores revelou significativa imunorreatividade das células e elementos celulares do G1 em relação aos outros grupos (p<0,001). Nesta análise evidenciou-se também acentuada imunorreatividade das células e elementos celulares de G2 e G3 em relação ao GC (p≤0,002). GFAP foi negativo em todos os grupos. Neste modelo, os achados permitem concluir que a hipercolesterolemia provoca anormalidades precoces histomorfométricas e imuno-histoquímicas do complexo esclerocoriorretiniano; e a ativação dos receptores do PPAR gama-ocular, a partir da dieta oral de rosiglitazona, foi efetiva em atenuar tais anormalidades nessas estruturas. / The purpose of this study is to evaluate scleral, choroid and retinal abnormalities in rabbits induced by a hypercholesterolemic diet and the prevention of these abnormalities after oral administration of rosiglitazone in rabbits. Fifty-four new zealand rabbits were divided into four groups: the control group (CG) was fed a normal diet; group 1 G1), a hypercholesterolemic diet; group 2 (G2) a hypercholesterolemic diet associated with daily administration of 3 mg of rosiglitazone from day 14 after the beginning of the diet; and group 3 G3), a hypercholesterolemic diet associated with daily administration of 3 mg of rosiglitazone since the beginning of the experiment. The rabbits were weighed and underwent the following examinations: seric dosages of total cholesterol, triglycerides, cholesterol HDL, and fasting glycemia at the beginning of the experiment, on the 14th day and on the 42nd, the euthanasia day. The sclera and choroid underwent histologic and histomorphometric analyses and the retina underwent immunohistochemical analysis with anti-calretinin (CR) and anti-glial fibrillary acidic protein (GFAP) antibody. When positive for the anti-calretinin marker, two quantitative analyses were performed. In the first analysis, all immunoreactive ganglion cells were counted. In the second analysis, all immunoreactive cells and cell elements were studied with the color morphometry method. The data were evaluated using the nonparametric Kruskal-Wallis and the Shapiro – Wilk tests. Values of p<0.05 were considered statistically significant. The results obtained showed a significant weight increase in Groups 1 and 3 in relation to CG on Day 14 (p<0.009). Additionally, a significant weight increase was observed in G1, G2 and G3 in relation to CG on Day 42 (p<0.023). The lab results showed a significant increase in glucose and total cholesterol in G1 in relation to CG (p<0.001) on Day 14, as well as a significant HDL increase in G3, when compared with the other groups (p<0.001) on Day 14. HDL in G3 was significantly high when compared to the other groups, on the euthanasia day (p<0.001). The results obtained regarding weight showed a significant increase in Groups 1, 2 and 3 in relation to CG on Day 14 (p<0.01) and Day 42 (p<0.02). The lab results showed a significant increase in glucose and total cholesterol in Groups 1, 2 and 3 in relation to CG (p<0.01) on Day 14, as well as a significant increase in HDL in G3 when compared with the other groups, on euthanasia day (p<0.01). The histomorphometric analysis of CG sclera and choroid presented normal results. Conversely, G1 showed a significant increase in sclera and choroid thickness in relation to CG (p= 0,008), whereas G3 showed thickness lower than in G1 (p=0,048). A larger number of histiocytes were observed on the scleral wall of the group that was fed the hypercholesterolemic diet (G1), followed, in a descending order, by groups 2 and 3, and the control group. The immunohistochemical analysis of the retina with the anti-calretinin monoclonal antibody showed that G1 presented a larger number of immunoreactive ganglion cells than G3 (p = 0.002). The color morphometry showed significant immunoreactivity of G1 cells and cell elements when compared with the other groups (p<0.001). A significant immunoreactivity of G2 and G3 cells and cell elements in relation to CG was also observed (p<0.002). GFAP results were negative in all groups. The findings of this proposed study model suggest that hypercholesterolemia induces early histomorphometric and immunohistochemical abnormalities in the sclerochorioretinal complex and that the activation of PPAR gamma in ocular cells attenuated these abnormalities with the administration of the oral rosiglitazone diet. / TEDE / BV UNIFESP: Teses e dissertações

Ansamling av amyloid beta (Aβ) i de extracellulära miljöerna är associerad till många svåra sjukdomar som Alzheimers och ålders-relaterad makuladegeneration (AMD). Amyloider karaktäriseras av att de är olösliga, toxiska mot neuron och orsakar därför svår skada. AMD är den ledande orsaken till blindhet och irreversibelt förlorande av skarp syn då Aβ manifesterar i makula. I AMD orsakar Aβ inflammatorisk aktivitet där det retinala pigmentepitelet bryts ned och ljuskänsliga fotoreceptorer dör genom apoptos. Idag lever ca 150 miljoner människor med AMD där mänga har svårt att utföra vardagliga uppgifter till följd av förlust av skarp syn. Idag är Kongo röd en av de vanligaste metoderna för att visualisera amyloider in vitro. Den patogenes som orsakas av amyloider kan analyseras med immunofluorescens och immunohistokemi. Syftet med studien var att undersöka förekomst av amyloider i samband med celldöd i näthinna från gris, undersöka den patogenes som amyloider orsakar med immunofluorescens och immunohistokemi, samt undersöka om det finns korrelation mellan amyloider och celldöd. Resultatet visade att amyloider var förekommande i näthinnan och hade orsakat celldöd och ansamling av aggresomer. Amyloider och den patologi som orsakats kunde visualiseras i det yttre lagret av näthinnan. / Deposition of amyloid beta (Aβ) in the extracellular environment are associated to some severe diseases, like Alzheimer’s disease and age-related macular degeneration (AMD). Amyloids are characterized by insolubility, toxicity towards neuron and are there-for damaging to tissues. AMD is the primary cause of blindness and irreversible loss of central vision through manifestation of Aβ in the macula. In AMD, Aβ drives an inflammatory action that degenerates the retinal pigment epithelium and cause atrophy of photoreceptors. Today ~150 million people live with AMD where many find difficulties performing everyday tasks due to loss of sharp vision. Congo red is a gold standard for visualizing amyloids in vitro and the pathogenesis caused by amyloids can be analyzed by immunofluorescence and immunohistochemistry. The purpose of this study was to show the presence of amyloids relating to cell death in pig retina, show the pathogenesis caused by amyloids by using immunofluorescence and immunohistochemistry, and investigate whether there is correlation between amyloids and cell death. The result showed that amyloids were present in the retina and caused cell death and gathering of aggresomes. Amyloids and the caused pathology could be visualized in the outer layer of the retina.

Sensory deprivation in one modality can enhance the development of the remaining modalities via mechanisms of synaptic plasticity. Mice of C3H strain suffers from RD1 retinal degeneration that leads to visual impairment at weaning age. Independently on the retinal degeneration there is also present olivocerebellar degeneration caused by Lurcher mutation. This neurodegenerative disorder causes motor deficits, increased CNS excitability as well as changes in synaptic plasticity. The aim of this study was to evaluate a role of whiskers in compensation of the visual deficit and to assess the influence of the olivocerebellar degeneration on this process. To differentiate contribution of the whiskers from other mechanisms that can take part in the compensation, we investigated the effect of both chronic and acute tactile deprivation. We focused on motor skills (rotarod, beam walking test), gait control (CatWalk system), spontaneous motor activity (open field) and the CNS excitability (audiogenic epilepsy). In the seeing mice without olivocerebellar degeneration, the removal of the whiskers had no effect. In the blind animals without olivocerebellar degeneration, chronic tactile deprivation caused changes in gait and impaired the performance in motor tests. Some other compensatory mechanisms were involved but the...

T cells infiltrate the degenerating brain and influence central nervous system (CNS) inflammation and neuronal health. In mice, the choroid plexus and the meninges have been implicated in regulating T cell entry and egress from the CNS, respectively. Further, antigen presenting cells in the mouse meninges present CNS-derived antigens to T cells and may represent a method for the peripheral immune system to sense and respond to CNS immune triggers. However, whether these processes occur in the human choroid plexus and meninges has not been comprehensively studied. Further, the antigens towards which T cells in the degenerating human brain and its borders respond remain unknown. Therefore, I implemented a multi-omics approach using fresh postmortem tissue from patients diagnosed with amyotrophic lateral sclerosis (ALS), Alzheimer’s disease (AD), Parkinson’s disease (PD), and non-neurodegenerative controls to identify not only the T cell-associated changes that occur in the degenerating human CNS and surrounding tissues but also identified a library of putative antigen targets for disease-associated T cell populations. Specifically, using single cell RNA and TCR sequencing information from paired postmortem choroid plexus, leptomeninges, and brain I lineage traced T cells using their TCR information and found that T cell access to leptomeninges and brain is likely limited and controlled by anti-inflammatory macrophage activity at the blood/CSF barrier (BCSFB). Once past the BCSFB, I present evidence that T cells access the CNS where they interact with MHC expressed by microglia. T cells also accumulate in the leptomeninges where they become tissue resident memory T cells. These tissue resident memory T cells likely serve as a reservoir for a rapid antigen-driven immune response to future CNS inflammatory insults. Finally, by performing immunopeptidomics to identify peptides presented by MHC in the same patients’ CNS and border tissues, I identified a library of putative antigenic triggers that may drive high levels of T cell clonal expansion in the brain and surrounding tissues. Altogether, this thesis serves as a resource for understanding the trajectory of T cells as they travel into the degenerating human brain and as a foundation for the development of antigen-specific precision medicines to treat neurodegeneration.

Yes / Microperimetry, also referred to as fundus perimetry or fundus-driven perimetry, enables simultaneous acquisition of visual sensitivity and eye movement data. We present sensitivity data collected from 60 participants with normal vision using gaze-contingent perimetry. A custom designed spatially dense test grid was used to collect data across the visual field within 13° of fixation. These data are supplemental to a study in which we demonstrated a spatial interpolation method that facilitates comparison of acquired data from any set of spatial locations to normative data and thus screening of individuals with both normal and non-foveal fixation (Denniss and Astle, 2016)[1].

Abnormal expression of the eukaryotic translation elongation factor 1A (eEF1A) has been implicated in disease states such as motor neuron degeneration and cancer. Two variants of eEF1A are found in mammals, named eEF1A1 and eEF1A2. These two variants are encoded by different genes, produce proteins which are 92% identical but have very different patterns of expression. eEF1A1 is almost ubiquitously expressed while eEF1A2 is expressed only in specialised cell types such as motor neurons and muscle. A spontaneous mutation in eEF1A2 results in the wasted mouse phenotype which shows similar characteristics in the mouse to those seen in human motor neuron degeneration. This mutation has been shown to be a 15.8kb deletion resulting in the complete loss of the promoter region and first non coding exon of eEF1A2 which completely abolishes protein expression. The main aim of this project was to further investigate the role of eEF1A2 in motor neuron degeneration. Firstly, although the wasted phenotype is considered to be caused by a recessive mutation, I established a cohort of aged heterozygote mice to evaluate whether any changes are seen later in life that might model late onset motor neuron degeneration. A combination of behavioural tests and pathology was used to compare wild type and heterozygous mice up to 21 months of age. Whilst results indicate that there is no significant difference between ageing heterozygotes and wildtype controls, there is an indication that female heterozygote mice perform slightly worse that wildtype controls on the rotarod (a behavioural test for motor function). Secondly, I aimed to investigate the primary cause of the wasted pathology by generating transgenic wasted mice expressing neuronal eEF1A2 only. This would complement previous experiments in the lab which studied transgenic wasted mice expressing eEF1A2 in muscle only. Unfortunately the expression of eEF1A2 in the transgenic animals was not neuronal specific. However a transgenic line with expression of eEF1A2 in neurons and skeletal muscle but not cardiac muscle has been generated which clearly warrants further investigation. Thirdly, I wished to assess whether eEF1A2 has any role in human motor neuron degeneration. To achieve this, eEF1A2 expression was investigated in spinal cords from human motor neuron disease (MND) patients. Preliminary data suggests that motor neurons from some MND patients express significantly less eEF1A2 than motor neurons of control samples. Further work is required to confirm these findings. Finally, I investigated the individual roles of eEF1A1 and eEF1A2 in the heat shock response. I used RNAi to ablate each variant separately in cells and subsequently measured the ability of each variant individually to mount a heat shock response. Results indicate a clear role for eEF1A1 but not eEF1A2 in the induction of heat shock. This may explain in part why motor neurons exhibit a poor heat shock response as they express eEF1A2 and not eEF1A1. These experiments shed light on our understanding of the role of eEF1A2 in motor neuron degeneration and uncover many new avenues of future investigation.

Thesis (MScMedSc)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Ataxia telangiectasia (AT) is a well-characterized neurodegenerative disease resulting from a genetic defect in the Atm gene causing an absence or very low expression of the ATM protein. As AT patients are prone to the development of insulin resistance and atherosclerosis, the aim or the current study was to investigate the importance of the ATM protein in the endothelium and its role in the signalling pathways of nitric oxide (NO) production. To accomplish this, the first objective was to establish an in-house endothelial cell isolation technique harvested from normal and insulin resistant animals. Unfortunately, these cultures, although staining positive with an endothelial cell specific stain, were not pure enough and did not express endothelial NO synthase (eNOS), the central enzyme in NO production. The remainder of the study utilized commercial aortic endothelial cells (AECs) and found that there was a significant increase in NO production when the ATM protein was inhibited by the specific inhibitor, Ku-60019. The beneficial impact of increased NO production includes maintaining vascular homeostasis, promoting angiogenesis, initiating DNA repair by activating p53 and inhibiting smooth muscle cell proliferation. On the other hand, reactive oxygen species (ROS) and reactive nitrogen species (RNS) also generated by high levels of NO, can exert both protective and harmful effects. Examples of these include cell death due to high concentrations of ROS. However, Ku-60019 did not result in increased cell death of AECs. We demonstrated for the first time, a relationship between endothelial ATM protein kinase and the generation of NO. The signalling pathways involved in NO production and glucose utilization form a network of interrelationships. Central to both pathways is the activity of two protein kinases, PKB/Akt and AMPK. Both these kinases are known to phosphorylate the eNOS enzyme to produce NO on the one hand and AS160 to induce GLUT 4 translocation and glucose uptake on the other hand. Activation of the ATM protein is postulated to be a prerequisite for PKB/Akt activation and it may also result in activation of AMPK. However, using insulin to stimulate ATM, we could not show that inhibition of ATM in endothelial cells affected expression or insulin-stimulated activation of PKB/Akt while the PI3-K inhibitor wortmannin, inhibited the latter. In addition, inhibition of ATM negatively regulated the phospho/total ratio of AMPK. We therefore postulate that the NO production elicited by inhibition of ATM, may not be as result of eNOS activity. A second important observation was that inhibition of ATM significantly enhanced phosphorylation of the p85 regulatory subunit of PI3-K. This would imply that ATM normally has an inhibitory effect on p85 phosphorylation and therefore PI3-K activation. We base this assumption on previous publications showing that Ku-60019 does not inhibit PI3K. This again indicates that ATM has a hitherto unexplored regulatory role in endothelial function. / AFRIKAANSE OPSOMMING: Ataxia telangiectasia (AT) is a goed-gekarakteriseerde neurodegeneratiewe siekte a.g.v. ‘n genetiese afwyking in the Atm geen wat lei tot ‘n afwesige of lae uitdrukking van die ATM proteïen. Aangesien AT pasiënte geneig is om insulienweerstandigheid en aterosklerose te ontwikkel, was die doel van hierdie studie om die belang van die ATM proteïen in die endoteel, en sy rol in die seintransduksiepaaie betrokke by stikstofoksied (NO) produksie, te ondersoek. Om dit te bereik, was die eerste mikpunt om ‘n eie endoteelsel isolasie-tegniek (ge-oes van normale en insulienweerstandige diere) te vestig. Ongelukkig was hierdie selkulture nie suiwer genoeg nie.Ten spyte daarvan dat hulle positief getoets het met ‘n endoteelsel-spesifieke kleurstof kon geen uitdrukking van eNOS, die sentrale ensiem verantwoordelik vir NO produksie, waargeneem word nie. Die res van die studie het van kommersiële aorta endoteelselle (AES) gebruik gemaak, en daar is gevind dat die inhibisie van die ATM proteïen met die spesifieke inhibitor, Ku-60019, tot ‘n beduidende toename in NO produksie gelei het. Die voordelige impak van verhoogde NO produksie sluit die handhawing van vaskulêre homeostase, bevordering van angiogenese, inisiëring van DNA herstel deur p53 aktivering en inhibisie van gladdespiersel proliferasie in. Reaktiewe suurstofspesies (ROS) en reaktiewe stikstofspesies (RNS) wat ook a.g.v.verhoogde NO gegenereer word, kan egter beide beskermende sowel as skadelike effekte uitoefen. Voorbeelde sluit seldood a.g.v. hoë ROS konsentrasies in. Ku-60019 het egter nie tot ‘n toename in seldood van die AES gelei nie. Hierdie studie het vir die eerste keer aangetoon dat daar ‘n verwantskap tussen die endoteel ATM proteïen kinase en die produksie van NO bestaan. Die seintransduksie paaie betrokke by NO produksie en glukose verbruik vorm ‘n interafhanklike netwerk. Die aktiwiteit van twee proteïen kinases, PKB/Akt en AMPK, is sentrale rolspelers in beide paaie. Albei hierdie kinases is daarvoor bekend dat hulle die eNOS ensiem fosforileer om NO te produseer, maar terselfdertyd ook lei tot AS160 fosforilering, wat tot GLUT 4 translokering en glukose opname lei. Dis is voorgestel dat aktivering van die ATM proteïen ‘n voorvereiste vir PKB/Akt aktivering mag wees en verder kan dit ook tot aktivering van AMPK lei. Ons kon nie aantoon dat inhibisie van ATM in endoteelselle die uitdrukking of insulien-geïnduseerde aktivering van PKB/Akt onderdruk nie, terwyl die PI3-K inhibitor, wortmannin, wel laasgenoemde geïnhibeer het. Verder het die inhibisie van ATM die fosfo/totale AMPK verhouding negatief gereguleer. Ons postuleer dus dat die NO produksie waargeneem tydens ATM inhibisie, moontlik nie die gevolg van eNOS aktiwiteit was nie. ‘n Tweede belangrike waarneming was dat die inhibisie van ATM die fosforilering van die p85 regulatoriese subeenheid van PI3-K beduidend laat toeneem het. Dit impliseer dat ATM normaalweg ‘n inhibitoriese effek op p85 fosforilering, en dus PI3-K aktivering, het. Hierdie aanname word gemaak n.a.v. vorige publikasies wat getoon het dat Ku-60019 nie PI3-K inhibeer nie. Dit dui weer eens daarop dat ATM ‘n tot nog toe onbekende regulatoriese rol in endoteelfunksie het.