No description available.

The validity of corneal confocal microscopy (CCM) in assessing peripheral neuropathy has been studied extensively in several studies with a large cohort of subjects with diabetes and in a handful of studies with small sample sizes in subjects with other systemic conditions. The non-invasive nature of this technique as well as its high reproducibility, moderate to high sensitivity and specificity, and ease of use make it an ideal biomarker for diagnosing onset, severity and progression of peripheral neuropathy. This thesis aims to further investigate the potential of CCM by evaluating abnormalities in the corneal sub-basal nerve plexus, Langerhans Cells (LCs) and epithelial cells in neuropathy related to diabetes and cancer. This thesis has established that evaluating the sub-basal nerve plexus in the centre and at the inferior whorl increases the diagnostic performance of CCM. In addition to diagnosing clinical and subclinical neuropathy in children and adults with diabetes CCM can also identify sub-clinical nerve damage in patients with upper gastrointestinal cancer and assess the effects of chemotherapy. CCM also identifies differences in small fibre pathology between diabetic patients with and without painful neuropathy. Although there was an increased prevalence and severity of dry eye and LCs' density, this was not related to an abnormality of corneal nerves in diabetic patients with no or mild neuropathy. Epithelial cell morphology was not associated with corneal nerve damage and did not alter in patients with Type 1 diabetes. In conclusion, CCM has been shown to be an ideal marker for quantifying early small fibre pathology and assessing peripheral neuropathies.

Rationale and hypothesis: Diabetic neuropathy involves dying back of nerve endings that reflects impairment in axonal plasticity and regenerative nerve growth. Metabolic changes in diabetes can lead to a dysregulation of hormonal mediators, such as cytokines. Thus I studied the effect of interleukin-17A (IL-17A), a proinflammatory cytokine produced by T-cells, on the phenotype of sensory neurons derived from control or diabetic rats. I hypothesized that IL-17A induces neurite outgrowth in sensory neurons through signaling pathways that enhance mitochondrial function. IL-17A can also reverse impaired nerve regeneration associated with diabetes Objectives: Determine the ability of IL-17A to enhance neurite outgrowth in cultured sensory neurons. Investigate the signalling pathways activated by IL-17A and mechanistically link to neurite outgrowth. Study the ability of IL-17A to improve mitochondrial function of sensory neurons (since axon outgrowth consumes high levels of ATP). Methodology: Cultured adult dorsal root ganglia (DRG) sensory neurons derived from age matched control or streptozotocin (STZ)-induced type 1 diabetic rats were fixed and stained for fluorescent imaging to determine total neurite outgrowth. Western blotting determined the levels of MAPK and PI-3K activation by IL-17A and for measuring levels of proteins of mitochondrial oxidative phosphorylation pathway. Mitochondrial bioenergetic function was tested in cultured DRG neurons using the Seahorse XF Analyzer. Results: I found that IL-17A (10 ng/ml; P<0.05) significantly increased total neurite outgrowth in cultures derived from both control and STZ-diabetic rat models. This enhancement was mediated by IL-17A-dependent activation of MAPK and PI-3K pathways with maximal effect at 15 minutes (P<0.05). Pharmacological blockade of one of these activated pathways led to total inhibition of neurite outgrowth. IL-17A improved mitochondrial bioenergetic function of sensory neurons. Bioenergetics function was associated with augmented expression of proteins of mitochondrial oxidative phosphorylation. Conclusion: IL-17A enhanced axonal plasticity through activation of MAPK and PI-3K pathways and was associated with augmented mitochondrial bioenergetics function in sensory neurons / October 2014

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1993. / Vita. Abstract. Includes bibliographical references (leaves 114-121). Also available via the Internet.

Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1994. / Vita. Abstract. Includes bibliographical references (leaves 167-187). Also available via the Internet.

Corneal Confocal Microscopy (CCM) is a non-invasive imaging technique to quantify small nerve fibre structure in patients with diabetic somatic and autonomic neuropathy and increasingly other metabolic, hereditary, toxic and inflammatory peripheral neuropathies. This thesis establishes that CCM is indeed a powerful imaging technique which can identify early small fibre degeneration and regeneration in relation to the clinical phenotype of subjects with obesity, impaired glucose tolerance and Type1/2 diabetes. We demonstrate a precise relationship between small fibre neuropathy and erectile dysfunction in subjects with Type 1 diabetes. We also demonstrate the utility of CCM in demonstrating relative protection from small fibre damage in Type 1 patients with extreme duration diabetes (medallists) at baseline and over 3 years and repair in patients undergoing simultaneous pancreas and kidney transplantation. This thesis provides further evidence for the utility of CCM as a marker of early small fibre neuropathy by demonstrating nerve damage in subjects with morbid obesity with and without diabetes and explore the mechanisms underlying nerve damage at baseline and repair following bariatric surgery. We also show that CCM can track dynamic changes in small fibre degeneration and regeneration in subjects with impaired glucose tolerance in relation to change in glucose tolerance status and following continuous subcutaneous insulin infusion in subjects with Type 1 diabetes.

Orientadores: Iscia Lopes Cendes, Anamarli Nucci / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas / Made available in DSpace on 2018-08-12T09:01:13Z (GMT). No. of bitstreams: 1 FrancaJunior_MarcondesCavalcante_D.pdf: 2508603 bytes, checksum: 7aaebc55cfad4e78c5723f324d24e71a (MD5) Previous issue date: 2008 / Resumo: A ataxia espinocerebelar tipo 3 ou doença de Machado-Joseph (SCA3/DMJ) é a ataxia autossômica dominante mais freqüente em nosso meio e tem como causa a expansão anormal do tripleto (CAG) no 10º éxon do gene MJD1 situado no cromossomo 14q. Trata-se de uma doença neurológica crônica e incapacitante cuja principal manifestação é a ataxia cerebelar, usualmente associada a disfunções piramidais, extra-piramidais, alterações da motilidade ocular extrínseca e neuropatia periférica (NP). Habitualmente, ocorre o envolvimento de múltiplas populações neuronais, tanto no sistema nervoso central (SNC) quanto periférico (SNP). No entanto, o envolvimento dos nervos periféricos na SCA3/DMJ apesar de freqüente e descrito previamente, é ainda pouco estudado. Nesse contexto, o objetivo desta pesquisa foi estudar o envolvimento do SNP na SCA3/DMJ, com o intuito específico de estimar a relevância de suas repercussões clínicas, determinar seus fatores causais e caracterizar sua história natural. Inicialmente, investigamos manifestações habituais em enfermidades do SNP mas pouco exploradas na SCA3/DMJ, como dor, câimbras e fasciculações,além de queixas de disautonomia. Em uma coorte de 70 indivíduos com SCA3/DMJ, encontramos dor crônica em 47% dos pacientes, na maior parte das vezes de padrão músculo-esquelético. Entretanto, a disfunção periférica também foi um fator associado a esse sintoma já que dois casos apresentaram dor de padrão neuropático em associação com neuropatia sensitiva. Em seguida, direcionamos atenção às câimbras e fasciculações. Estas também foram manifestações comuns na doença, identificadas em 82% e 50% dos pacientes, respectivamente. As câimbras eram, em muitos casos, uma queixa significativa, dificultando o sono e o trabalho. A presença de NP esteve intimamente relacionada com o surgimento de fasciculações, mas aparentemente não com as câimbras. Entretanto, ambas estiveram associadas com anormalidades da excitabilidade dos motoneurônios, expressas por alterações nos parâmetros das ondas F e do reflexo H. Tal fato possivelmente está relacionado com os bons resultados que obtivemos no tratamento das câimbras mediante o uso da carbamazepina, um bloqueador de canais iônicos. Sintomas disautonômicos foram relatados com freqüência na SCA3/DMJ, em particular aqueles relacionados com os sistemas urogenital e sudomotor. O estudo da resposta simpática cutânea mostrou-se um bom instrumento para identificar pacientes com disautonomia significativa. Nesse grupo em particular, verificamos uma maior proporção de pacientes com fenótipo "parkinsoniano" e "neuropático". O próximo passo foi estabelecer o padrão de acometimento do SNP e sua evolução utilizando estudo de eletroneuromiografia (ENMG). NP foi diagnosticada em 54% dos pacientes com SCA3/DMJ; alguns com envolvimento exclusivamente sensitivo, outros sensitivo-motor e poucos exclusivamente motor. As anormalidades neurofisiológicas são compatíveis com uma dupla neuronopatia, afetando motoneurônios alfa e células ganglionares. No estudo pospectivo, verificamos que a neuropatia é um fenômeno idade-dependente na SCA3/DMJ, mas a progressão é mais rápida naqueles indivíduos com maior alelo expandido. De maneira contrária, verificamos que a progressão da ataxia cerebelar não está associada ao tamanho do alelo expandido, mas à idade de início. Isto sugere que os determinantes da progressão da NP e da ataxia possam ser diferentes. Em nossa amostra, o tamanho do alelo expandido foi responsável por quase 70% da variabilidade na idade de início da doença. Como descrito, ele também contribuiu para a evolução da NP, mas seu efeito ficou em torno de 40%. Portanto, outros fatores possivelmente genéticos também devem modificar o fenótipo na SCA3/DMJ. Averigüamos o efeito de dois possíveis candidatos, o alelo normal e a co-chaperona C-terminal heat shock protein 70-interacting protein (CHIP), em modelos de regressão com múltiplas variáveis utilizando a idade de início como dependente. Não observamos efeito que pudesse ser atribuído a proteína CHIP; entretanto, o alelo normal parece oferecer uma pequena, mas significativa contribuição para a determinação da idade de início (cerca de 2%). Resta definir se este efeito estende-se a outros elementos do fenótipo, como a expressão de NP. / Abstract: Machado-Joseph disease or spinocerebellar ataxia 3 (SCA3/MJD) is the most frequent autosomal dominant ataxia in Brazil and caused by an unstable trinucleotide (CAG) repeat expansion in the 10th exon of the MJD1 gene on chromosome 14q. It is a chronic and debilitating neurologic disorder characterized by cerebellar ataxia, pyramidal dysfunction, dystonia, gaze abnormalities and peripheral neuropathy. Different types of neurons both in the central and peripheral nervous system are usually damaged in the disease. Although there are previous reports of peripheral involvement in patients with SCA3/MJD, there are still many unanswered questions. Therefore, we have designed this study aiming to evaluate the damage to the peripheral nervous system in SCA3/MJD, with especial emphasis on its clinical relevance, causative factors and natural history. We first looked at manifestations typically found in peripheral neuropathies, such as pain, muscle cramps, fasciculations, and disautonomia, but frequently overlooked in SCA3/MJD. In a cohort of 70 individuals with SCA3/MJD, we found chronic pain in 47% of patients, most of them with musculoskeletal characteristics. Peripheral dysfunction was also a contributing factor since at least two patients reported neuropathic pain in association with a predominantly sensory polyneuropathy. We then assessed muscle cramps and fasciculations and found that these were also common complaints, present in 82% and 50% of patients, respectively. Cramps were often a major complaint, disturbing sleep or work hours. We reported positive results with carbamazepine in the treatment of cramps in patients with SCA3/MJD. Peripheral neuropathy was clearly related to fasciculations, but not to muscle cramps. However, both manifestations were associated to abnormal excitability of motor neurons, as expressed by F-wave and H-reflex responses. Dysautonomia was another typical feature of patients with SCA3/MJD, and symptoms related to genitourinary and sudomotor systems were particularly frequent. Sympathetic skin response proved to be useful in the screening of patients with severe dysautonomia. We found higher proportions of patients with either "parkinsonian"or "neuropathic" phenotypes among those with severe autonomic impairment. In addition, we used nerve conductions studies and electromyography to determine the pattern of damage to the peripheral nervous system and its course over the time. We showed that overall 54% of patients with SCA3/MJD had peripheral neuropathy. Some of those had exclusive sensory impairment, others sensory-motor, and a few restricted motor involvement. The neurophysiological studies showed that the peripheral neuropathy in SCA3/MJD resembles a double neuronopathy, involving alpha motor neurons and dorsal root ganglia. Prospective data indicate that the peripheral involvement is mostly age-dependent, but progression is faster in individuals with larger (CAG) expansions. By contrast, progression of ataxia was mostly driven by age at onset, rather than length of expanded (CAG) repeat. These findings suggest that the determinants of damage to peripheral and cerebellar neurons may be different. The length of the expanded (CAG) allele explained roughly 70% of the variability in age at onset of the disease. As reported previously, it also contributes to progression of peripheral neuropathy, but this effect is small (40%). Therefore, other factors could exist, possibly genetic factors, which could influence the phenotypic variability in SCA3/MJD. We tested two potential genetic factors as candidates, the normal allele and the gene for the co-chaperone CHIP. We used regression models with age at onset as the dependent variable in the statistical analysis. We failed to show any modulating effect due to the protein CHIP. Nevertheless, the normal allele had a small, but significant contribution to variability in age at onset (about 2%). It remains to be determined whether this effect extends to other aspects of the phenotype, such as the peripheral damage. / Doutorado / Neurologia / Doutor em Ciências Médicas

No description available.

No description available.

Rationale and hypothesis: Diabetic sensory neuropathy involves a distal dying-back of nerve fibers. Neuronal mitochondrial function is impaired in diabetes and Sirtuin 2 (SIRT2) is a sensor of redox state that regulates cellular bioenergetics. The role of SIRT2 in regulating the phenotype of adult sensory neurons derived from both control and diabetic rats or wild type and SIRT2 knockout (KO) mice was studied. It was hypothesized that sensory neurons under a hyperglycemic state would have a lowered NAD+/NADH ratio thus deactivating the SIRT2 pathway. It was further hypothesized that the down regulation of SIRT2 would diminish the activity of the AMP-activated protein kinase (AMPK) pathway resulting in mitochondrial dysfunction. This defect would contribute to distal dying-back of axons observed in diabetes. Methodology: Type 1 diabetes was induced in rodents by streptozotocin (STZ). Adult sensory neurons derived from control or STZ-diabetic rats or control and SIRT2 knockout (KO) mice were cultured in defined media with varying doses of neurotrophic factors and D-glucose. Protein levels were determined by quantitative Western blotting and neurite outgrowth quantified by immunocytochemistry. Plasmid transfection was initiated for overexpression of SIRT2 constructs and Seahorse XF24 analyzer was utilized to measure mitochondrial function of cultured neurons. Results: Overexpression of SIRT2 elevated total neurite outgrowth in cultures derived from control and STZ-diabetic rats. Cultures derived from SIRT2 KO mice exhibited diminished neurite outgrowth. The AMPK pathway was inhibited under high glucose treatment through activation of the polyol pathway. Pharmacological inhibition of the polyol pathway improved mitochondrial bioenergetics and neurite outgrowth in sensory neurons. Augmented expression of electron transport proteins and increased mitochondrial mass was associated with enhanced bioenergetic function. Conclusion: SIRT2 is a key component driving mitochondrial function and axon regeneration through the activation of AMPK pathway. In diabetes this pathway is suppressed via elevated polyol pathway activity. / October 2016