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Diss. (sammanfattning) Umeå : Umeå universitet, 2006. / Härtill 4 uppsatser.

Thesis (Ph. D.)--Michigan State University. Dept. of Neuroscience, 2008. / Title from PDF t.p. (viewed on Aug. 19, 2009) Includes bibliographical references (p. 294-324). Also issued in print.

Synaptic transmission is a mechanism that makes life possible for many organisms. Damaging this crucial process, such as with a buildup of Reactive Oxygen Species (ROS), is extremely detrimental for the entire organism. Previously, the Dawson-Scully lab has determined that exposure of the Drosophila melanogaster neuromuscular junction (NMJ) to ROS accumulation can result in synaptic failure at a faster rate than saline controls (Caplan et al., 2013). To combat such effects, novel three-dimensional Resveramorph compounds were created to act as a neuroprotective agent against the harmful effects of acute oxidative stress (Bollinger et al., 2019; Sial et al., 2019). With the initial Resveramorph compounds demonstrating neuroprotective effects, additional analysis of other Resveramorph compounds were of interest to better understand their role in neuroprotection. Further testing of these compounds allows for the investigation of how chemical structure affects a compound’s neuroprotective activity. / Includes bibliography. / Thesis (MS)--Florida Atlantic University, 2021. / FAU Electronic Theses and Dissertations Collection

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Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / A Pilocarpina à um agonista colinÃrgico caracterÃstico por induzir convulsÃes que evoluem para status epilÃpticus, similar à epilepsia do lobo temporal humana. Neste presente trabalho, nÃs avaliamos a possÃvel aÃÃo neuroprotetora da doxiciclina, uma tetraciclina de segunda geraÃÃo, nas convulsÃes induzidas pela pilocarpina em ratos Wistar machos, que receberam pilocarpina (300mg/kg i.p) presenÃa ou na ausÃncia de doxiciclina (25 à 100 mg/kg) administrada intraperitonealmente uma vez ao dia durante sete dias. ApÃs a injeÃÃo de pilocarpina, foram observados os sinais colinÃrgicos perifÃricos, as latÃncias de 1 convulsÃo e de morte. Foram determinadas as concentraÃÃes de aminoÃcidos no cÃrtex temporal atravÃs de cromatografia lÃquida de alta eficiÃncia HPLC, e a atividade do sistema antioxidante, catalase e as dosagens dos nÃveis de TBARS e nitrito. Os resultados mostraram que a doxiciclina nÃo alterou os sinais colinÃrgicos perifÃricos, contudo aumentou a latÃncia decorrida para a primeira convulsÃo (1.6 a 5 vezes), quando comparada ao grupo (P300). Resultados semelhantes foram demonstrados com a latÃncia de morte, que foi aumentada de 1.9 a 9.9 vezes. Observou - se que o prÃ-tratamento com doxiciclina 50 mg/kg foi capaz de reduzir em 25% os nÃveis de MDA, 64% os nÃveis de nitrito e 67.7% a atividade da catalase no cÃrtex temporal desses animais, demonstrando com clareza seu potencial antioxidante. Interessantemente, a doxiciclina diminuiu as concentraÃÃes de glutamato de 28 a 33%, e aumentou GABA em 112 e 91%, nas dose de 50 e 100mg/kg respectivamente nos animais administrados com P300, Na maior dose, a droga alterou os nÃveis de aspartato e taurina, diminuindo em 61% aspartato enquanto elevou os nÃveis de taurina em cerca de 34%. Surpreendentemente, somente a menor dose alterou os nÃveis de glicina, aumentendo a concentraÃÃo deste aminoÃcido em 132%. Em conclusÃo, mostramos que o inÃcio e a intensidade das convulsÃes induzidas pela pilocarpina foram significativamente reduzidos pela doxiciclina. Portanto, pelo menos em parte, este mecanismo de aÃÃo parece estar relacionado a uma diminuiÃÃo nos nÃveis de aminoÃcidos excitatÃrios e a um aumento nas concentraÃÃes de aminoÃcidos inibitÃrios no cÃrtex temporal desses animais. / Pilocarpine is known to induce convulsions leading to status epilepticus, similar to the temporal lobe epilepsy in humans. In the present work, we evaluated the possible protection affored by doxycyvline, a 2nd generation tetracycline, agaist pilocarpine- induced convulsions in male Wistar rats (P300mg/kg, i.p) in the absence and in the presence of doxicycline (25 to 100 mg/kg i.p.) daily for 7 days.After the pilocarpine injection, all groups were observed for cholinergic signs, latency to the first convulsion and latency to death. Besides, amino acid concentrations in temporal cÃrtices were determined by RP-HPLC, as well catalase activity and levels of TBARS and Nitrite. Results showed that doxycycline did not alter cholinergic signs but increased the latency time to the first convulsion (1.6 to 5 times increase), as compared to P300, and the highest effect was observed with the dose of 25 mg/kg. Similar results were demonstrated to death latency that increased from 1.9 to 9.9 times with doxyciclyne at the doses of 25, 50 and 100 mg/kg. In fact we showed that the pre-treatment with doxycycline decreased in 25% MDA levels, 64% nitrite levels and 67.7% catalase activity. Interestingly, doxycycline decreased glutamate concentrations in 28 and 33% and increased GABA in 112 and 91% at the doses of 50 and 100mg/kg respectively. At the higher dose the drug altered aspartate and taurine concentrations, decreased aspartate levels in 61%, while increasing taurine levels in 34%. Surprisingly, only the lower dose altered glycine levels, increasing its concentration by 132%. In conclusion, we showed that the onset and intensity of pilocarpine-induced seizures were significantly reduced by doxycycline. Furthermore, at least in part, its mechanism of action seems to be mediated by the decrease and increase of excitatory and inhibitory aminoacids, respectively. In addiction the doxycycline capacity to reduce the oxidative stress associated with the pilocarpine-induced may also play a role

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Un daño agudo al sistema nervioso central (SNC) desencadena una serie de eventos complejos e interrelacionados, entre los cuales encontramos tres especialmente importantes: excitotoxicidad, estrés oxidativo e inflamación. En particular, el cerebro inmaduro muestra varias características que lo hacen especial en cuanto a sus reacciones frente a lesioned agudas. En este contexto, la presente Tesis contribuye al conocimiento básico de los procesos de estrés oxidativo e inflamación que ocurren luego de una lesión excitotoxica mediada por inyección de NMDA en el cerebro inmaduro. Asimismo, desarrolla estrategias neuroprotectoras mediante la utilización de nuevos vectores de terapia génica combinados con la sobreexpresión de enzimas antioxidantes. Esta Tesis muestra que la expresión de una de las enzimas antioxidantes más importantes, la Cu/Zn superoxide dismutase (SOD), en el cerebro inmaduro normal se observa principalmente en neuronas, pero también en la glia limitans y la pared de los ventrículos cerebrales. Sin embrago, 4 horas después de una lesión excitotóxica, la enzima muestra una importante reducción en las neuronas afectadas por la lesión aguda inicial, ocurriendo esto antes de que estas neuronas iniciaran un proceso de muerte neuronal. A partir del primer día postlesión la expresión de SOD comienza a aumentar en astrocitos reactivos. La nitrotirosina, un producto del peroxinitrito, en el cerebro inmaduro luego de la lesión mostró un incremento en neuronas del núcleo de la lesión, y al día 1 postlesión también se observó en astocitos. Es interesante destacar que los astrocitos nitrados a partir de los 3 días postlesión delimitaban una subpoblación celular mostrando como características principales un alto grado de hipertrófia, elevados niveles de GFAP, expresión de novo de vimentina y SOD, y expresando metalotiooneina I/II, siendo siempre los astrocitos más reactivos. Asimismo, a pesar de encontrarse altamente nitrados y expresar la caspasa 3 activa en su núcleo, estos astrocitos no mostraron ningun signo morfológico de muerte celular ni tinción para TUNEL, lo cual sugiere que estas células no mueren al menos hasta los 7 días postlesión. Esta Tesis se centró seguidamente en el desarrollo de nuevas estrategias de terapia génica basadas en vectores proteicos modulares recombinantes. Cuando estos vectores fueron inyectados intracerebralmente 4 horas luego de la lesión, fueron capaces de transfectar células en toda la zona lesionada del cerebro inmaduro. Asimismo, fueron capaces de transfectar tanto neuronas como astrocitos y microglía, sin generar inflamación adicional. Con estos resultados prometedores, una de estos vectores se utilizó para sobreexpresar la SOD 2 horas luego de la lesión. Esta sobreexpresión indujo una disminución en los niveles de nitrotirosina, una disminución en el volúmen de lesión, un aumento en la supervivencia neuronal, y una recuperación funcional significativa cuando se compararon con animales lesionados e inyectados con solución salina control. Sorprendentemente, esta Tesis muestra que estos vectores poseen un potencial neuroprotector endógeno, que es mediado por sus dominios de interacción con integrinas Arg-Gly-Asp (RGD), ya que la inyección in vivo de un pequeño péptido ciclico con la secuencia RGD también resultó neuroprotector a niveles similares. En cultivos celulares mixtos de corteza cerebral, tanto los vectores como el péptido RGD fueron protectores frente a un daño inducido por NMDA, pero no lo fueron en cultivos purificados de neuronas corticales, sugiriendo que el efecto neuroprotector es dependiente de células gliales.Esta Tesis concluye que el estrés oxidativo, y en particular la vía del superóxido/peroxinitrito, contribuyen de manera fundamental al desarrollo de una lesión aguda en el cerebro inmaduro. Asimismo, la sobreepresión de SOD puede ser una interesante estrategia neuroprotectora. Finalmente, concluye que los vectores proteicos recombinantes modulares pueden actuar eficientemente in vivo luego de una lesión aguda al cerebro inmaduro, produciendo niveles terapéuticos de proteinas neuroprotectoras. / Acute central nervous system (CNS) damage consists of a multitude of inter-related and complex events, playing excitotoxicity, oxidative stress and inflammation important roles in the initial and secondary injury. In particular, the immature brain displays several characteristics that make it special in its reactions against acute injuries. In this context, this Thesis contributes to the basic understanding of the oxidative stress and inflammation occurring after an NMDA-mediated excitotoxic lesion to the immature brain, and to the development of neuroprotective gene therapy strategies for reducing immature brain damage by inhibiting oxidative stress. This Thesis shows the in vivo expression and cell localization of one of the most important antioxidant proteins, Cu/Zn superoxide dismutase (SOD), whose expression was observed mainly in neuronal cells, glia limitans and ependyma in the normal immature brain. However, after an excitotoxic lesion, the expression of this enzyme rapidly disappeared (at 4 hours) from the acutely affected neurons before they underwent cell death. One day after, expression of SOD begun to increase in reactive astrocytes, present in the lesion for up to 7 days, the last time studied. Moreover, in the normal brain, the peroxynitrite product nitrotyrosine was observed in neurons and scattered astrocytes, however, after the excitotoxic lesion it was early increased in neurons of the lesion core, and after at 1 day post-lesion it increased also in astrocytes. Interestingly, the nitrated hypertrophied astrocytes from 3 days post-lesion onward represented a separated population of cells sharing several markers such as vimentin, metallothionein, SOD, and high GFAP content and hypertrophy, being always phenotypically the most reactive astrocytes. In addition, although being heavily nitrated and showing activated caspase 3 in their nuclei, nitrated astrocytes did not display any morphological sign of cell death nor TUNEL staining at any time-point studied. The next step of this Thesis was to explore the putative beneficial effects of the overexpression of SOD after the NMDA excitotoxic lesion. This Thesis focused on the development of a new gene therapy strategy based on a non-viral modular recombinant protein vector. These vectors could deliver a transgene to the whole excitotoxically lesioned zone of the immature brain when injected 4 hours after the lesion. Moreover, they could transfect neurons, astrocytes and microglial cells, without generating additional inflammation. With these promising results, one of these protein vectors was used for overexpressing SOD 2 hours after the excitotoxic lesion. SOD overexpressing animals displayed decreased nitrotyrosine formation, reduced lesion volume, increased neuronal survival, and a complete functional recovery after 3 days in relation to NMDA+saline injected animals. Surprisingly control lesioned animals injected with the protein vector overexpressing the transgene for the green fluorescent protein or with the naked protein vector without any DNA, showed also a reduced lesion volume. Finally this Thesis showed that the neuroprotective potential of the protein vectors was mediated by the vectors integrin-interacting Arg-Gly-Asp (RGD) motif, as a cyclic RGD peptide was sufficient to induce this neuroprotection. Accordingly, both the protein vector and the cyclic RGD peptide were neuroprotective against a NMDA mediated injury to mixed cortical cultures. However, none of these molecules were neuroprotective under the same treatment conditions in cortical neuron purified cultures, suggesting that the neuroprotective mechanisms include triggering of a glial derived neurotrophic phenotype. This Thesis concludes that oxidative stress, and in particular the O2-./ONOO- pathway is a mayor contributor to lesion expansion in the acutely injured immature brain, and that the overexpression of SOD is an interesting neuroprotective strategy. In addition, it shows that modular recombinant protein vectors are efficient gene therapy vectors that can be applied to therapeutic interventions to the acutely lesioned immature brain.

Thesis (Ph. D.)--University of Hong Kong, 2010. / Includes bibliographical references (leaves 181-212). Also available in print.

Acute glaucoma is an ocular emergency and sight -threatening disease which is caused by a sudden increase in intraocular ocular pressure (IOP) due to blockage of aqueous humor outflow. Acute glaucoma can result in permanent loss of visual acuity and visual field (VF). Prophylactic or therapeutic medicine is rare for acute glaucoma. In animal studies, a well-established model to investigate this acute IOP spike is by fluid infusion and adjustment of the fluid level to induce high IOP within a few seconds. However, there is no blockage of aqueous outflow and the increase in intraocular pressure is unrealistically rapid. To mimic the IOP profile in human acute glaucoma attack, we propose the use of an ophthalmic viscosurgical device (OVD), Healon 5 (AMO, Santa Ana, CA, USA) which is injected intracamerally to block aqueous outflow. The IOP is allowed to increase naturally inside the globe. We found that Healon 5 can induce an acute elevation in IOP with very similar characteristics to those observed in humans. For example, the IOP profile during the attack, changes in the anterior segment and retinal nerve fibre layer (RNFL) thinning are all consistent with findings in human acute angle closure glaucoma (AACG). We believed that our new model can more accurately reflect acute glaucoma than other animal models. Based on these findings we further tested the neuroprotective effect of Lycium barbarum polysaccharides (LBP) on retinal neurons against an acute rise in IOP (attack) with the new model. L. barbarum is an herb that has been used in Chinese medicine for thousands of years. The fruit of this plant is believed to be good for the health of the eyes. In our study we found that oral administration of LBP preceding an acute glaucoma attack can preserve the visual function of the animals despite the loss of neurons in the retinal ganglion cell layer (RGCL). L. barbarum intake seems to inhibit secondary cell death and progression of the disease. In conclusion, we had successfully established a new acute glaucoma attack animal model by intracameral injection of Healon 5. This model more closely resembles the condition observed in human acute glaucoma. We also found that LBP has a prophylactic neuroprotective effect against an acute glaucoma attack in animals. It can protect the visual function and possibly inhibit secondary cell death. Oral consumption of LBP as a health supplement may provide extra benefit to people who are at high risk of developing acute glaucoma, in addition to the protective effects of LBP against other diseases. / published_or_final_version / Anatomy / Master / Master of Philosophy