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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
181

Motives of Log Schemes

Howell, Nicholas 06 September 2017 (has links)
This thesis introduces two notions of motive associated to a log scheme. We introduce a category of log motives à la Voevodsky, and prove that the embedding of Voevodsky motives is an equivalence, in particular proving that any homotopy-invariant cohomology theory of schemes extends uniquely to log schemes. In the case of a log smooth degeneration, we give an explicit construction of the motivic Albanese of the degeneration, and show that the Hodge realization of this construction gives the Albanese of the limit Hodge structure.
182

Randomized controlled clinical trials for the evaluation of efficacy and safety of Chinese medicine in treatment of neurodegenerative diseases

Chua, Ka Kit 14 August 2015 (has links)
Background: Neurodegenerative diseases (NDD) are very common in the aging population, of which Parkinson’s disease (PD) and Alzheimer disease (AD) are the two most common. Since the etiology of the neuronal death in these diseases remains unclear, currently no curative therapy is available. Traditional Chinese medicine (TCM) has been used to treat certain diseases, which based on their symptoms we now know that they are included PD and AD, for thousands of years. However, our pervious systematic review reports that the quality of current TCM clinical trials related to this area had limited internal validity due to methodological flaws and insufficient data reporting. Methods: This study includes two add-on double-blinded randomized controlled trials (RCT), PD full-scale study and AD pilot study. It aims to provide evidence for the efficacy and safety of two specific TCM decoctions, Jia-Wei-Liu-Jun-Zi Tang (JWLJZT) and Di-tan decoction (DTD) in treating PD and AD, respectively. These clinical trials follow the Consolidated Standards of Reporting Trials (CONSORT) as well as the International Conference on Harmonization guidelines on Good Clinical Practice (GCP). Also, this two RCT obtained the approval from the Human and Animal Research Ethics Committee of Hong Kong Baptist University before the study and registered on the Chinese Clinical Trial Registry. Result: In the PD trial, 111 idiopathic PD patients were randomly assigned to receive either JWLJZT or placebo for 32 weeks. Although there was not significant difference in the primary outcome of Movement Disorder Society Sponsored Revision of Unified PD Rating Scale (MDS-UPDRS) Part I total score (p = 0.216), significant improvements was observed in the secondary outcome of Non-motor symptom assessment scale for Parkinson’s disease (NMSS) total score (p = 0.019), subtype of mood/cognition (p = 0.005) and hallucinations (p = 0.024). In addition, post-hoc analysis showed a significant reduction in constipation (p < 0.001). On the other hand, 40 AD patients were randomly assigned to receive either DTD or placebo for 24 weeks in the AD trial. There was an improvement trend in the primary outcome of the cognitive subscale of Alzheimer’s Disease Assessment Scale (ADAS-cog) total score in the DTD group though the difference relative to the placebo group was not statistically significant (p = 0.315). No significant difference was found in the secondary outcomes. Adverse events were mild and comparable between treatment and placebo groups in both trials. Discussion: JWLJZT did show some improvement in non-motor symptoms, including mood, cognition, and constipation, in PD patients, while, DTD did show a reducing trend in the cognitive impairment based on rigorous RCT. Further study focusing on the effective dosage, pharmacologic mechanism of JWLJZT and DTD are needed to give a fuller picture as well as better support for using them in human being as a routine treatment. In fact, JWLJZT and DTD are the only two examples of TCM for treating NDD. These two clinical trials are served as examples of how to evaluate efficacy and safety of TCM for the treatment of various diseases using rigorous RCT methods and standard. Keywords: Randomized Controlled Trials, Parkinson’s disease, Alzheimer disease, Traditional Chinese medicine, Jia-Wei-Liu-Jun-Zi Tang, Di-tan decoction, Efficacy, Safety
183

Differential changes in gene expression in cultured human retinal pigment epithelial cells after beta-amyloid stimulation

Kurji, Khaliq 05 1900 (has links)
Age related macular degeneration (AMD) is the most common cause of irreversible vision loss in the elderly. At present, there are an estimated one million people in Canada with some form of AMD and this number is expected to double to two million by 2031. These estimates are sobering, and it is predicted that costs for treatment and care of individuals who suffer vision loss from AMD will have significant impact on the social and public health systems in Canada in the next two decades. There are treatments to slow the progression of vision loss, but unfortunately, there are currently no cures available for AMD. In order to develop effective second generation therapies and cures, further insights into how and why AMD develops are greatly needed. Recent studies have provided novel insights into the role of inflammation in the pathogenesis of AMD. Inflammation, or swelling of the retinal tissues, causes harmful processes that promote macular degeneration. The proposed studies will focus on the triggers of inflammation in the retina. It is hypothesized that macular degeneration may be slowed or stopped by eliminating the molecules that cause inflammation in the retina. This study will focus on amyloid beta (Aβ), a toxic molecule that has been implicated in retinal inflammation, and the role that it may play in gene expression of the retinal pigment epithelial cell. Amyloid beta is a well studied peptide in another age related disorder, Alzheimer’s disease. It is the major extracellular deposit in Alzheimer’s disease plaques, and has recently been discovered as a component of drusen, the hallmark extracellular deposits in the retina of patients with the ‘dry’ form of AMD. These studies will allow the development of new treatment regimens that target retinal inflammation and thus minimize the processes that ‘trigger’ the onset of macular degeneration. / Medicine, Faculty of / Graduate
184

On Newton-Okounkov bodies, linear series and positivity

Merz, Georg 08 March 2018 (has links)
No description available.
185

An investigation into the possible neuroprotective or neurotoxic properties of metrifonate

Ramsunder, Adrusha 11 June 2013 (has links)
Alzheimer's disease is a progressive neurodegenerative disorder, in which there is a marked decline in neurotransmitters, especially those of the cholinergic pathways. One of the approaches to the symptomatic treatment of Alzheimer's disease is the inhibition of the breakdown of the neurotransmitter acetylcholine, using an acetylcholinesterase inhibitor. One such drug tested, is the organophosphate, metrifonate. Any drug used for the treatment of neurodegenerative disorders should preferably not induce further neurological damage. Thus, in the present study, we investigated whether or not metrifonate is neuroprotective. The in vivo and in vitro effect of this drug on free radicals generation shows that metrifonate increases the level ofthese reactive species. Lipid peroxidation induced using quinolinic acid (QA) and iron (II) and show that metrifonate increased the peroxidative damage induced by using quinolinic acid. Metrifonate is also able to induce lipid peroxidation both in vivo and in vitro. This was reduced in vitro in the presence of melatonin. Using iron (II), in vi/ro, there was no significant difference in the level of lipid peroxidation in the presence of this drug. An investigation of the activity of the mitochondrial electron transport chain and complex I of the electron transport chain in the presence of metrifonate revealed that metrifonate reduces the activity of the electron transport chain at the level of complex I. The activity of the mitochondrial electron transport chain was restored in the presence of melatonin. Pineal organ culture showed that metrifonate does not increase melatonin production. Histological and apoptosis studies show that tissue necrosis and apoptosis respectively, occur in the presence of this agent, which is reduced in the presence of melatonin. Metal binding studies were performed USing ultraviolet spectroscopy, and electrochemical analysis to examine the interaction of metrifonate with iron (II) and iron (III). No shift in the peak was observed in the ultraviolet spectrum when iron (ll) was added to metrifonate. Electrochemical studies show that there may be a very weak or no ligand formed between the metal and drug. This study shows that while drugs such as metrifonate may be beneficial in restoring cognitive function in Alzheimer's disease, it could also have the potential to enhance neurodegeneration, thus worsening the condition, in the long term. / KMBT_363 / Adobe Acrobat 9.54 Paper Capture Plug-in
186

An investigation into the possible neuroprotective properties of phenytoin

Naga, Nishal January 2002 (has links)
Cerebral ischaemia, traumatic injury to the brain, inflammatory neurological disorders and HIV infections are amongst the most prevalent causes of neurodegeneration. Neuroprotective strategies are usually to limit the progressive secondary injury that generally occurs, thus limiting overall tissue damage. Neuroprotective strategies are usually to limit the progressive secondary injury that generally occurs, thus limiting overall tissue damage. Sodium channel blockers have been often used for this matter as they prevent the cascade of events culminating in free radical generation and eventually neuronal apoptosis. Newer compounds, such as antiperoxidants and free radical scavengers, show encouraging experimental results, but their clinical use is still very limited. Phenytoin being a popular drug in the treatment of epilepsy has also been used as a neuroprotectant during certain neurological emergencies and in pharmacological prophylaxis of post-traumatic epilepsy. Furthermore this agent functions by prolonging inactivation of voltage gated sodium channels. In these sets of experiment the neuroprotective properties of phenytoin were examined. The histological study revealed that phenytoin confers protection to the CA1 and CA3 regions of the hippocampus under the insult of QUIN. Cells maintain their characteristic shape and minimal tissue necrosis occurs in the presence of this agent. The in vitro effect of this antiepileptic drug on free radicals generation shows that phenytoin does not reduce or prevent the formation of these reactive species. Lipid peroxidation was induced using QUIN and iron (II), two known neurotoxins. The study reveals that only lipid peroxidation induced using iron (II) is reduced by phenytoin. These experiments were carried out in whole rat brain homogenate. These studies show that phenytoin possesses poor free radical scavenging properties. However, the dose-related reduction of iron-induced lipid peroxidation allows for speculation that phenytoin interacts with iron in order to reduce neuronal damage. Metal binding studies were performed using UV, IR and electrochemical analysis to examine the interaction of phenytoin with iron (II) and iron (III). Phenytoin, when added to iron (II) in solution, first oxidises the latter to iron (III) and maintains it in that form. A shift in the peak was observed in the UV spectrum when iron was added to phenytoin. Moreover, electrochemical studies indicate that the interaction between the metal and the ligand is very weak. The IR analysis it shows that phenytoin may be coordinating with iron through the Nitrogen atom on the phenytoin molecule. These studies show that phenytoin maintains iron in its oxidised form, which is a good property to possess as a neuroprotectants. Pineal organ culture showed that phenytoin does not increase melatonin production but slightly and non-significantly reduces the levels of this pineal hormone. However there is a significant rise in precursor NAS levels. As melatonin is known to possess antioxidant and free radical scavenging properties, this could mean that this drug can cause the CNS to become more susceptible to attacks by reactive oxygen species.
187

Specific Alleles of CLN7/MFSD8, a Protein That Localizes to Photoreceptor Synaptic Terminals, Cause a Spectrum of Nonsyndromic Retinal Dystrophy

Khan, Kamron N., El-Asrag, Mohammed E., Ku, Cristy A., Holder, Graham E., McKibbin, Martin, Arno, Gavin, Poulter, James A., Carss, Keren, Bommireddy, Tejaswi, Bagheri, Saghar, Bakall, Benjamin, Scholl, Hendrik P., Raymond, F. Lucy, Toomes, Carmel, Inglehearn, Chris F., Pennesi, Mark E., Moore, Anthony T., Michaelides, Michel, Webster, Andrew R., Ali, Manir 06 June 2017 (has links)
PURPOSE. Recessive mutations in CLN7/MFSD8 usually cause variant late-infantile onset neuronal ceroid lipofuscinosis (vLINCL), a poorly understood neurodegenerative condition, though mutations may also cause nonsyndromic maculopathy. A series of 12 patients with nonsyndromic retinopathy due to novel CLN7/MFSD8 mutation combinations were investigated in this study. METHODS. Affected patients and their family members were recruited in ophthalmic clinics at each center where they were examined by retinal imaging and detailed electrophysiology. Whole exome or genome next generation sequencing was performed on genomic DNA from at least one affected family member. Immunofluorescence confocal microscopy of murine retina cross-sections were used to localize the protein. RESULTS. Compound heterozygous alleles were identified in six cases, one of which was always p.Glu336Gln. Such combinations resulted in isolated macular disease. Six further cases were homozygous for the variant p.Met454Thr, identified as a founder mutation of South Asian origin. Those patients had widespread generalized retinal disease, characterized by electroretinography as a rod-cone dystrophy with severe macular involvement. In addition, the photopic single flash electroretinograms demonstrated a reduced b- to a-wave amplitude ratio, suggesting dysfunction occurring after phototransduction. Immunohistology identified MFSD8 in the outer plexiform layer of the retina, a site rich in photoreceptor synapses. CONCLUSIONS. This study highlights a hierarchy of MFSD8 variant severity, predicting three consequences of mutation: (1) nonsyndromic localized maculopathy, (2) nonsyndromic widespread retinopathy, or (3) syndromic neurological disease. The data also shed light on the underlying pathogenesis by implicating the photoreceptor synaptic terminals as the major site of retinal disease.
188

Distribution of Light in the Human Retina under Natural Viewing Conditions

Gibert, Jorge C. 12 September 2013 (has links)
Age-related macular degeneration (AMD) is the leading cause of blindness inAmerica. The fact that AMD wreaks most of the damage in the center of the retina raises the question of whether light, integrated over long periods, is more concentrated in the macula. A method, based on eye-tracking, was developed to measure the distribution of light in the retina under natural viewing conditions. The hypothesis was that integrated over time, retinal illumination peaked in the macula. Additionally a possible relationship between age and retinal illumination was investigated. The eye tracker superimposed the subject’s gaze position on a video recorded by a scene camera. Five informed subjects were employed in feasibility tests, and 58 naïve subjects participated in 5 phases. In phase 1 the subjects viewed a gray-scale image. In phase 2, they observed a sequence of photographic images. In phase 3 they viewed a video. In phase 4, they worked on a computer; in phase 5, the subjects walked around freely. The informed subjects were instructed to gaze at bright objects in the field of view and then at dark objects. Naïve subjects were allowed to gaze freely for all phases. Using the subject’s gaze coordinates, and the video provided by the scene camera, the cumulative light distribution on the retina was calculated for ~15° around the fovea. As expected for control subjects, cumulative retinal light distributions peaked and dipped in the fovea when they gazed at bright or dark objects respectively. The light distribution maps obtained from the naïve subjects presented a tendency to peak in the macula for phases 1, 2, and 3, a consistent tendency in phase 4 and a variable tendency in phase 5. The feasibility of using an eye-tracker system to measure the distribution of light in the retina was demonstrated, thus helping to understand the role played by light exposure in the etiology of AMD. Results showed that a tendency for light to peak in the macula is a characteristic of some individuals and of certain tasks. In these situations, risk of AMD could be increased. No significant difference was observed based on age.
189

Avaliação do polimorfismo 'RS10490924' do gene 'LOC387715' em uma população brasileira com degeneração macular relacionada à idade / Assessment of the 'LOC387715' gene polymorphism 'RS10490924' in a brazilian population with age-related macular degeneration

Hirata, Fabio Endo, 1980- 28 August 2018 (has links)
Orientador: Mônica Barbosa de Melo / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas / Made available in DSpace on 2018-08-28T01:54:14Z (GMT). No. of bitstreams: 1 Hirata_FabioEndo_M.pdf: 1885791 bytes, checksum: ccde99235ea9bbbcda8608e4c5aaf996 (MD5) Previous issue date: 2015 / Resumo: Introdução: A degeneração macular relacionada à idade (DMRI) é uma doença crônica degenerativa que afeta a área macular da retina causando diminuição da visão central. É a causa mais comum de perda visual irreversível nos países desenvolvidos. A DMRI é caracterizada pela presença de drusas, anormalidades do epitélio pigmentar da retina (EPR), atrofia geográfica, descolamento do EPR, neovascularização de coróide e cicatriz disciforme. Sua etiologia permanece pouco esclarecida, entretanto fatores genéticos associados a fatores ambientais possuem papel na etiologia e na progressão da doença. Dentre as variações gênicas, uma associação entre o polimorfismo Ala69Ser do gene LOC387715/ARMS2 ( rs10490924 C/T ) e o desenvolvimento da DMRI tem sido relatada em diferentes populações. Objetivo: O objetivo deste estudo foi avaliar se o polimorfismo rs10490924 está associado com a DMRI em uma amostra da população brasileira. Métodos: Cento e vinte e seis pacientes, sem parentesco, com DMRI (idade média de 74,17 ± 7,64) foram comparados com 86 controles saudáveis (idade média 71,82 ± 7,12). Os sujeitos do estudo foram classificados de acordo com o tipo de DMRI em DMRI seca e DMRI exsudativa. O polimorfismo LOC387715/ARMS2 rs10490924 foi avaliado através da reação em cadeia da polimerase e sequenciamento direto. Resultados: A frequência do alelo T foi significativamente maior em pacientes com DMRI do que nos controles (39,6% em comparação com 20,3%, p = 0,00002). O odds ratio (OR) para DMRI foi de 2,05 (IC95 % 1,09-3,89 ) para os heterozigotos (TG) e 8,45 ( IC95 % 2,21-37,82 ) para homozigotos (TT). Conclusões: Os resultados sugerem que há uma contribuição do SNP rs10490924 do gene LOC387715/ARMS2 para susceptibilidade à DMRI nesta amostra da população brasileira / Abstract: Introduction: Age-related macular degeneration (AMD) is a chronic degenerative disease that affects the macular area causing decreased central vision. It is the most common cause of irreversible vision loss in developed countries. It is characterized by the presence of drusen, abnormalities of the retinal pigment epithelium (RPE), geographic atrophy, RPE detachment, choroidal neovascularization, and disciform scar. The etiology of AMD remains poorly understood, but genetic factors associated with environmental factors have a role in the etiology and progression of the disease. Among the analyzed genetic variations, an association between LOC387715/ARMS2 (rs10490924) gene polymorphism and AMD has been reported in different populations. Purpose: The aim of this study was to evaluate whether this polymorphism is associated with AMD in a Brazilian cohort. Methods: A hundred and twenty six unrelated AMD patients (mean age 74.17 ± 7.64) were compared with 86 healthy controls (mean age 71.82 ± 7.12). Study subjects were classified according to the type of AMD in dry and wet AMD. The LOC387715/ARMS2 rs10490924 polymorphism was evaluated through polymerase chain reaction and direct sequencing. Results: The T allele frequency was significantly higher in AMD patients than controls (39.6% compared to 20.3%, p = 0,00002). The odds ratio (OR) for AMD was 2.05 (CI95% 1.09-3.89) for heterozygotes (TG) and 8.45 (CI95% 2.21-37.82) for homozygotes (TT). Conclusions: These results suggest that there is a contribution of the rs10490924 SNP of the LOC387715/ARMS2 gene to AMD susceptibility in this sample of Brazilian population / Mestrado / Oftalmologia / Mestre em Ciências Médicas
190

Neuroprotective effects of a novel TFEB activator E4 and its self-carried nanoparticles in MPTP-induced Parkinson's disease models

Wang, Ziying 03 September 2019 (has links)
Parkinson's disease (PD) is one of the most common neurodegenerative diseases characterized by cell death in the substantia nigra pars compacta (SNpc) and the appearance of aggregated α-synuclein (α-syn). Autophagosomes accumulation and lysosomal reduction were discovered in PD patients' brain, which indicated the deficiency of autophagy in the progress of PD. TFEB (transcription factor EB) is a member of basic helix -loop-helix-leucine-zipper transcription factors (MiT family) and is a key master monitor for autophagy and lysosome biogenesis. Overexpression of TFEB is able to rescue the dopaminergic neurons (DAs) loss and α-syn aggregated in α-syn transgenic mice model and MPTP PD model. Hence, in recent years, many researchers have considered TFEB as a new therapeutic target for PD In this study, we discovered a novel TFEB activator named E4 by screening synthesized curcumin analogs. We have found that E4 strongly promoted TFEB nuclear translocation and induced autophagy in different cell lines. TFEB is essential for E4-induced autophagy flux. We also demonstrated that the underlying mechanism of E4 activate TFEB is mainly through inhibiting mTORC1 activity. We constitutively activate mTOR by knockdown TSC2 abrogated the increase of LC3-II and decrease of p-TFEB. We further estimated the protective effects of E4 in overexpressed α-syn model and neurotoxins induced cytotoxicity model. Treated with E4 for 48h in N2a transfected with A53T α-synuclein cells dose-dependently reduce the α-synuclein level. At the same time, we established the MPP+ model in PC12 cells which is pre-treated cell with E4 for 6 hours and then co-treated cells with MPP+ for 48 hours. The cell viability results showed that E4 significantly protect PC12 cells against MPP+ cytotoxicity dose-dependently. E4 had shown good neuroprotective effects in PD in vitro models while poor water solubility and low brain permeability restricted its application in PD animal models. Hence, assembling E4 molecules into self-carried nanoparticles (NanoE4) addressed the issue of poor water solubility and intranasal administration solved the problem of low permeability. In order to track NanoE4 release in vitro and in vivo, we further investigated the absorption and emission of NanoE4. However, the absorption fluorescence results showed that NanoE4 exhibits the strong aggregation-caused quenching effect (ACQ) due to π-π stacking of the planar molecule within the NPs. NanoE4 have much weak emission compared with E4 molecules. Therefore, we fabricated E4-TPAAQ NPs by co-reprecipitating E4 molecules with the reported fluorescent organic compound TPAAQ (2,6-Bis[4-(diphenylamino) phenyl] anthraquinone). Next, we developed an intranasal drug delivery system in our lab. After intranasal co-drop nanodrug E4-TPAAQ NPs for 24 hours, we observed strong fluorescence distributed in the brain which indicated that deliver nanoparticles into the brain successfully through nasal-brain system. Therefore, we examined the protective effect of NanoE4 in MPTP-induced PD mice model. In MPTP models, we found autophagy dysfunction, motor function decrease and increase of α-synuclein as reported previously. Treatment with NanoE4 rescued the motor dysfunction induced by MPTP. NanoE4 also increase TH level in the striatum part of midbrain. NanoE4 treatment also decreased the α-synuclein protein aggregate in both SNpc and striatum. Overall, these results demonstrate the neuroprotection NanoE4 against PD. Collectively, our findings 1) discovered a novel TFEB activator E4 that inhibited the mTOR pathway 2) indicated in vitro and in vivo experimental evidence for TFEB activator as the anti-PD drug candidate 3) provide a novel drug develop and delivery system for potential PD that limited by water solubility and BBB (blood-brain barrier) obstacle

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