Introdução: A doença de Huntington é uma doença neurodegenerativa autossômica dominante causada pela expansão de um segmento repetitivo CAG no gene HTT. Caracteriza-se por transtornos do movimento, em especial coreia, alterações comportamentais e declínio cognitivo. A doença tem um curso progressivo e inexorável. Objetivos: Este estudo tem os seguintes objetivos: (1) revisar de forma sistemática os estudos sobre doença de Huntington na América Latina; (2) determinar a proporção de casos brasileiros com fenótipo doença de Huntington que são portadores da expansão no gene HTT; (3) caracterizar as transmissões CAGexp na coorte HTT e determinar se idade do genitor está associado à piora das instabilidades; (4) descrever a progressão das manifestações neurológicas, IMC e concentrações séricas de carnitina livre, valina, leucina e isoleucina durante o período de seguimento; (5) definir se as progressões desses candidatos a biomarcadores acompanham a piora neurológica e podem superar a sensibilidade da escala UHDRS na descrição da progressão da doença. Métodos: Realizamos uma revisão sistemática dos aspectos genéticos da doença de Huntington na América Latina. Em seguida recrutamos pacientes com o fenótipo doença de Huntington de vários centros do país através da Rede Neurogenética e avaliamos a proporção de diagnósticos confirmados. Nas famílias provenientes de nosso centro e dos hospitais São Paulo (UNIFESP) e Gaffrée e Guinle (UNIRIO), recrutamos indivíduos sintomáticos e em risco para caracterizar as transmissões CAGexp e avaliar fatores que determinam as instabilidades. Nos mesmos centros que avaliamos as transmissões, selecionamos um grupo de indivíduos sintomáticos e em risco para determinar as concentrações séricas de carnitina livre, valina, leucina e isoleucina e as correlacionar com variáveis de gravidade da doença (IMC, escala UHDRS). O comportamento desses potenciais biomarcadores foi avaliado de forma prospectiva em um grupo de indivíduos sintomáticos. Resultados: Constatamos a escassez de estudos sobre aspectos moleculares da doença de Huntington na América Latina e Brasil. Das 104 famílias com fenótipo doença de Huntington recrutadas em diversos centros do Brasil, 93 (89,4%) apresentavam expansão CAG no gene HTT; 4 (3,8%) apresentam o diagnóstico de HDL-2 (Huntington’s disease-like 2); 1 (1%) apresentam expansão CAG no gene ATXN2 (SCA2); e 6 (5,8%) ficaram sem diagnóstico. Um número substancial de portadores foi recrutado e permitiu estimar a prevalência mínima da doença, ao menos no Rio Grande do Sul. Além disso, trinta e duas transmissões de genitor para filho (13 paternas e 19 maternas) foram obtidas nessa coorte. As transmissões paternas foram mais instáveis do que as maternas (p=0.005, Mann- Whitney). As transmissões paternas foram mais frequentemente expansões (69,2% expansões) e as maternas foram mais estáveis (57,9% estáveis) (p=0,004, Fisher). Em 51 pares de irmãos incluídos, a idade do progenitor no momento da concepção não pareceu estar relacionada com aumento da instabilidade do CAGexp. Na avaliação dos potenciais biomarcadores, incluímos 116 indivíduos (74 sintomáticos, 20 portadores assintomáticos e 22 não portadores). No baseline, os níveis (mediana/intervalo interquartil) de valina estavam reduzidos tanto em indivíduos sintomáticos (110 / 88,4-131) como nos portadores assintomáticos (101,25 / 79,6-123,5) em comparação com não portadores (123 / 98.65– 164.25) (p=0.018 e p=0.042, Mann-Whitney). Não houve diferença entre os grupos nos níveis de carnitina e isoleucina+leucina (ns, Kruskal-Wallis). Na avaliação de seguimento em 43 indivíduos sintomáticos (mediana=1,08 anos), o escore motor total da UHDRS aumentou 4,8 pontos (p = 0.001, GEE) e a escala funcional TFC reduziu 0,89 pontos (p <0.0001, GEE). O IMC (p=0,52, GEE) e os níveis de valina (p=0,43, GEE) permaneceram estáveis e os níveis de carnitina (p=0,039, GEE) e isoleucina+leucina (p=0,037, GEE) aumentam durante o seguimento. Conclusão: Os resultados desses estudos conseguiram traçar um perfil mais acurado da doença de Huntington no Brasil, tanto do ponto de vista epidemiológico quanto no comportamento das transmissões CAG nas famílias identificadas. A progressão da doença, medida pela UHDRS, foi semelhante à observada em coortes do Hemisfério Norte. Além disso, verificamos que a carnitina livre e os aminoácidos de cadeia ramificada não são bons biomarcadores de progressão na doença de Huntington. / Introduction: Huntington's disease is an autosomal dominant neurodegenerative disease caused by an expansion of a repetitive CAG segment in the HTT gene. Movement disorders (especially chorea), behavioral problems and cognitive decline characterize the disease, which has an inexorable progression. Up to now, there is no disease modifying treatment for Huntington's disease. Objectives: This study aimed to address the following objectives: (1) review, in a systematic manner, studies of Huntington's disease in Latin America; (2) determine the proportion of cases with Huntington's disease phenotype that are carriers of the expansion in the HTT gene; (3) characterize CAGexp transmissions in the HTT cohort and determine a possible association of the age of the parent with further instability of CAGexp; (4) describe the progression of neurological manifestations, BMI and serum concentrations of free carnitine, valine, leucine and isoleucine during a follow-up period; (5) determine whether changes in time of these compounds are correlated with the simultaneous neurological worsening and if they may overcome the sensitivity of the UHDRS scale in describing the progression of the disease. Methods: We performed a systematic review of the genetic aspects of Huntington's disease in Latin America. We then recruit patients with the Huntington's disease phenotype from various centers throughout the country through the Rede Neurogenética and evaluate the proportion of confirmed diagnoses. In families from our center and hospitals São Paulo (UNIFESP) and Gaffrée and Guinle (UNIRIO), we recruit symptomatic and at-risk individuals to characterize CAGexp transmissions and evaluate factors that determine instabilities. In the same centers that evaluated the transmissions, we selected a group of symptomatic and at-risk individuals to determine serum free carnitine, valine, leucine, and isoleucine levels and to correlate them with disease severity variables (BMI, UHDRS scale). The behavior of these potential biomarkers was evaluated prospectively in a group of symptomatic individuals. Results: We found a lack of studies on genetic aspects of Huntington's disease in Latin America and Brazil. Ninety-three (89.4%) out of 104 families with Huntington's disease phenotype recruited in several centers in Brazil had CAG expansion in the HTT gene; 4 (3.8%) had the diagnosis of HDL-2 (Huntington's disease-like 2); 1 (1%) a CAG expansion in the ATXN2 gene (SCA2); and 6 (5.8%) remained undiagnosed. Two hundred and seventy-nine carriers were included in our cohort, allowing to estimate the minimal prevalence of disease in Rio Grande do Sul as 1.85/100,000. Thirty-two transmissions (13 paternal and 19 maternal) were obtained. Parental transmission was more unstable than maternal transmission (p = 0.005, Mann-Whitney). Parental transmission most often expanded (69.2%), and maternal was more often stable (57.9% stable) (p = 0.004, Fisher). In 51 pairs of siblings included, age of the progenitor at conception did not appear to be related to increased instability of CAGexp. A total of 116 individuals (74 symptomatic, 20 asymptomatic carriers and 22 non-carriers) were included in the biomarkers analysis. At baseline, valine (median / interquartile range) levels were reduced in both symptomatic (110 / 88.4-131) and asymptomatic carriers (101.25 / 79.6-123.5) when compared to non-carriers (123 / 98.65- 164.25) (p = 0.018, p = 0.042, Mann-Whitney). There was no difference between groups in their levels of carnitine and isoleucine + leucine (ns, Kruskal-Wallis). In the follow-up evaluation in 43 symptomatic individuals (median = 1.08 years), the total motor score of the UHDRS increased by 4.8 points (p = 0.001, GEE) and the functional TFC scale decreased 0.89 points (p <0.0001, GEE). BMI (p = 0.52, GEE) and valine levels (p = 0.43, GEE) remained stable and levels of carnitine (p = 0.039, GEE) and isoleucine + leucine (p=0.037, GEE) increased during follow-up. Conclusion: The results of these studies drew a more accurate profile of Huntington's disease in Brazil, since they generated both a minimal prevalence in our region and the behavior of CAG transmissions in the Brazilian families. Disease progression as measured by UHDRS was similar to the progression rate observed in cohorts from the North Hemisphere. In addition, we have found that free carnitine and branched-chain amino acids are not suitable to be considered good biomarkers of HD progression.

Huntington disease (HD) is a degenerative neurological disease that typically onsets in midlife. It leads to progressively severe impairment in cognitive, behavioral, and motor function and premature death. Persons who test positive for the HD gene expansion know they will develop the disease. Research indicates changes are detectable several years before onset. Thus, HD has a long prodromal period (prHD). While researchers are aware of changes, little is known whether persons with prHD or their companions notice changes, or how they make sense of and cope with them. Leventhal and colleagues developed the Common Sense Model of Illness Representation (CSM) to describe how people make sense of illness. According to the CSM, people notice somatic changes, form illness representations, select coping procedures and evaluate them, and reappraise illness representations in an iterative process. The CSM has been used to explore illness representations in a variety of illnesses, including diagnosed HD. The authors of the model state it is also applicable in anticipated illness but this assertion has not been adequately tested. The purpose of this thesis was to use the CSM to explore and describe illness representations in persons with prHD and their companions. The results of this exploration are presented in three papers. The first paper, presented in Chapter 2, was a preliminary study based on interview data from 8 persons and 7 companions. Results of this analysis indicated persons with prHD and companions noticed and made attributions for changes, suggesting they formed illness representations. However, they were unsure whether some changes were related to HD. Results were considered preliminary because participants were not directly asked to make attributions. Data were also limited to changes in work function and the sample size was small. In the next two papers, 23 couples were interviewed. The purpose of the second paper, presented in Chapter 3, was to explore illness representations in persons with prHD and their companions and evaluate the usefulness of the CSM in anticipated illness using prHD as a model. Results supported preliminary findings: Participants noticed changes, made attributions, used coping strategies and evaluated them. Again, they unsure whether some changes were related to HD. Other elements of the CSM were partially supported by the data. The third paper, presented in Chapter 4, used quantitative and qualitative methods to explore coping in persons with prHD and companions. Participants were asked open-ended questions about how they coped with changes and were also verbally administered the Brief COPE scale. Both quantitative and qualitative data showed participants used active coping, acceptance, planning, and social support. Participants rarely used denial or substance abuse. Persons with prHD used more coping strategies than companions. Three major themes from the qualitative interview were identified: trying to fix it, can't fix it, and not broken yet. Qualitative interviews revealed some coping strategies that the Brief COPE did not measure. Findings from these papers may inform interventions to help people with prHD and companions cope with changes. Persons with prHD and companions might benefit from knowing what changes might be related to HD in order to cope more effectively.

En el desarrollo de esta tesis doctoral nos hemos centrado en el estudio de diferentes vías de señalización intracelular implicadas en los procesos de supervivencia y muerte neuronal en el contexto de la enfermedad de Huntington, con el objetivo de entender cómo la presencia de la proteína "htt" mutada afecta de forma específica a la normal viabilidad y supervivencia de las neuronas GABAérgicas del núcleo estriado.En un primer trabajo se estudió la implicación de los sistemas glutamatérgicos y dopaminérgicos en la mayor vulnerabilidad de las células estriatales. Los resultados obtenidos nos demostraron que la presencia de la htt mutada potencia la muerte celular inducida por la activación de los receptores glutamatérgicos y dopaminérgicos. Asimismo, demostramos que el efecto neurotóxico asociado a la activación glutamatérgica y dopaminérgica está mediado por una aberrante activación de la vía de la quinasa Cdk5. De esta manera, la htt mutada incrementa la sensibilidad estriatal al glutamato y a la dopamina, modificando una vía de señalización común a ambos sistemas, la vía de Cdk5.En un segundo trabajo se analizó si la alteración en los niveles del receptor TrkB asociada a la expresión de la htt mutada se traduce en una anómala señalización intracelular en respuesta a BDNF. Los resultados obtenidos nos permitieron concluir que en presencia de la htt mutada se produce una específica alteración en la vía de señalización de TrkB-ERK1/2. Además, comprobamos que la menor activación de esta vía intracelular conlleva una mayor susceptibilidad de las células estriatales frente a un estímulo de estrés oxidativo inducido con H2O2.De acuerdo con los resultados obtenidos en esta tesis, la mayor vulnerabilidad de las neuronas estriatales frente a la presencia de la htt mutada podría ser el resultado de (1) una sobreactivación de vías intracelulares con un efecto neurotóxico, como sería, en este caso, la vía de Cdk5 tras una estimulación glutamatérgica y dopaminérgica, y (2) una menor activación de las vías intracelulares involucradas en el mantenimiento de la supervivencia neuronal, como es la vía de ERK1/2.La identificación y caracterización de los diferentes mecanismos moleculares responsables de la selectiva muerte neuronal en la enfermedad de Huntington puede ser de gran utilidad para el futuro diseño de nuevas terapias farmacológicas que permitan retrasar o prevenir la progresión de la enfermedad.

Thèse de doctorat : Biologie : Evry-Val d'Essonne : 2008. / Titre provenant de l'écran-titre.

This case study is in an effort to demonstrate the disastrous effects of modernization via social mobilization and economic development when initiated from above and through foreign intrusion. Initially, this research will examine previous theoretical literature regarding the political phenomenon of modernization and social mobilization. My primary focus will center on the problems that occur when rapid modernization, based on an exogenous model, is forced onto a traditional society by elites and social mobilization outpaces political institutionalization. My case study will focus on the country of Iran, as the political and societal factors of interest seem to be highly illustrative of the period leading up to the revolution. A brief historical analysis will be conducted. I will then analyze Iran from 1953 to 1979 by looking at the policies of the shah and the Western influence of those policies, the evidence of social mobilization that may have taken place, any moves towards urbanization, possible affects on traditional groups, and the state of political institutionalization. This study's central argument is that rapid modernization through social mobilization while lacking political institutionalization results in instability and possibly revolution. This study is being conducted in an effort to demonstrate the validity of this proposed political phenomenon by analyzing Iran in the years leading-up to the revolution.

In neurons, modification by the lipid palmitate regulates trafficking and function of signaling molecules, neurotransmitter receptors and associated synaptic scaffolding proteins. HIP14 (huntingtin interacting protein 14) is the first identified and characterized mammalian palmitoyl transferase that regulates this process. I have shown that HIP14 has striking effects on modulating trafficking and function of many proteins important for synapse formation and plasticity such as PSD-95, a postsynaptic scaffolding molecule. The importance of the finding that HIP14 is a neuronal palmitoyl transferase is further emphasized by our recent discovery that huntingtin protein folding, trafficking and function are regulated by the enzyme HIP14. Expansion of the polyglutamine tract in huntingtin as seen in Huntington Disease (HD) results in reduced association with HIP14 and decreased palmitoylation of huntingtin, which contributes to the formation of inclusion bodies and enhanced neuronal toxicity. By manipulating HIP14 levels through expression or knockdown, we can manipulate the number of huntingtin inclusion bodies and neuronal cell viability. Overall, these discoveries offer novel mechanism for HD pathogenesis and provide new approaches to therapy for HD. The tight association of HIP14 with wild-type huntingtin, which differs from other known enzyme-substrate interactions, indicates that huntingtin serves other functions beyond being a substrate of HIP14. I have discovered that, in vitro, wild-type huntingtin may facilitate activity of HIP14 to palmitoylate other neuronal substrates such as SNAP25, PSD95 and GAD65. By contrast, mutant htt does not act this way, probably due to lack of interaction with HIP14. Furthermore, immunoprecipitated HIP14 from huntingtin+/- mice also exhibits less enzyme activity in palmitoylating GST-SNAP25 in vitro, suggesting that decreased huntingtin expression compromises HIP14 activity. In vivo, using Acyl Biotin Exchange assay, I have also found that palmitoylation of a number of presynaptic and postsynaptic proteins that are involved in neurotransmission are reduced in huntingtin+/- mice. This study not only ascribes an important biochemical function to wild-type huntingtin, but also suggests that defects in protein palmitoylation in general due to mutant huntingtin lack of ability to facilitate HIP14 activity may contribute to the pathogenesis of HD.

In neurons, modification by the lipid palmitate regulates trafficking and function of signaling molecules, neurotransmitter receptors and associated synaptic scaffolding proteins. HIP14 (huntingtin interacting protein 14) is the first identified and characterized mammalian palmitoyl transferase that regulates this process. I have shown that HIP14 has striking effects on modulating trafficking and function of many proteins important for synapse formation and plasticity such as PSD-95, a postsynaptic scaffolding molecule. The importance of the finding that HIP14 is a neuronal palmitoyl transferase is further emphasized by our recent discovery that huntingtin protein folding, trafficking and function are regulated by the enzyme HIP14. Expansion of the polyglutamine tract in huntingtin as seen in Huntington Disease (HD) results in reduced association with HIP14 and decreased palmitoylation of huntingtin, which contributes to the formation of inclusion bodies and enhanced neuronal toxicity. By manipulating HIP14 levels through expression or knockdown, we can manipulate the number of huntingtin inclusion bodies and neuronal cell viability. Overall, these discoveries offer novel mechanism for HD pathogenesis and provide new approaches to therapy for HD. The tight association of HIP14 with wild-type huntingtin, which differs from other known enzyme-substrate interactions, indicates that huntingtin serves other functions beyond being a substrate of HIP14. I have discovered that, in vitro, wild-type huntingtin may facilitate activity of HIP14 to palmitoylate other neuronal substrates such as SNAP25, PSD95 and GAD65. By contrast, mutant htt does not act this way, probably due to lack of interaction with HIP14. Furthermore, immunoprecipitated HIP14 from huntingtin+/- mice also exhibits less enzyme activity in palmitoylating GST-SNAP25 in vitro, suggesting that decreased huntingtin expression compromises HIP14 activity. In vivo, using Acyl Biotin Exchange assay, I have also found that palmitoylation of a number of presynaptic and postsynaptic proteins that are involved in neurotransmission are reduced in huntingtin+/- mice. This study not only ascribes an important biochemical function to wild-type huntingtin, but also suggests that defects in protein palmitoylation in general due to mutant huntingtin lack of ability to facilitate HIP14 activity may contribute to the pathogenesis of HD.

Thèse (M.Sc.)--Université Laval, 2007. / Bibliogr.: f. [68]-74. Publié aussi en version électronique dans la Collection Mémoires et thèses électroniques.

Thesis Erasmus University Rotterdam. / ook verschenen in gedrukte versie. With bibliogr., with a summary in Dutch.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1975. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Bibliographical footnotes.