Diss. (sammanfattning) Stockholm : Karol inst., 2004. / Härtill 5 uppsatser + appendix.

Submitted by Mario BC (mario@bc.ufrpe.br) on 2016-08-03T13:24:26Z No. of bitstreams: 1 Emanuel Felipe de Oliveira Filho.pdf: 682058 bytes, checksum: 56dfe31080d213c1dac81fc60832e1eb (MD5) / Made available in DSpace on 2016-08-03T13:24:26Z (GMT). No. of bitstreams: 1 Emanuel Felipe de Oliveira Filho.pdf: 682058 bytes, checksum: 56dfe31080d213c1dac81fc60832e1eb (MD5) Previous issue date: 2016-02-22 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The outbreak enzootic ataxia in lambs was recorded in the municipality of Garanhuns, rugged region of the state of Pernambuco, involving 18 sheep (17 females and one male). The animals were raised in extensive system without regular supply in mineral supplementation, grass fed Brachiaria sp. and pangola grass (Digitaria decumbens) as well as water ad libitum. The sheep underwent clinical evaluation, laboratory and pathology. The clinical condition of the animals ranged from one week to 15 days, between the signs are noteworthy apathy, anorexia, weight loss, anemia, change in color of the wool, amaurosis, incoordination of the hind limbs, difficulty in locomotion with weakness of the hind limbs, position of "dog sitting", decreased sensory and motor responses, frequent falls and difficulty to stay in season and episodes of diarrhea. Serum values of Cu was (6.88 ± 4.31 mmol / L) below the reference range (9-15 mmol / L), the concentration of Mo (≤0,05 mmol / L), while the Fe was (44.02 ±28.51 mmol / L) and Zn was (16.13 ± 7.87 mmol / L), were within the normal range for the species. In the analysis of the relation between Fe, Zn and Cu of affected lambs enzootic ataxia, evidence was low negative correlation between the serum concentration of Fe with Cu (r = -0.19) and between serum Zn Cu (r = -0.07). Histopathology vacuolization were observed, the presence of axonal spheroids and myelin debris, which are engulfed by macrophages with foamy cytoplasm, together with mild demyelination of the white matter. The primary deficiency of Cu causes the occurrence of AE in South Agreste region of Pernambuco state, since the deficiency was due to inadequate intake of this trace element in the diet and not by the action of antagonists such as Fe, Zn and Mo. In addition, the lack of Cu in sheep raised in the wild region of Pernambuco is important issue to be considered in mineral nutrition and should be recommended proper supplementation of Cu. Objective was to evaluate the effects of crude glycerin inclusion containing 80.5% glycerol on the blood parameters of lambs in confinement. They were used 39 crossbred lambs without breed standard set, uncastrated male with four months of age and initial body weight of 21 kg ± 0.8 kg, distributed in randomized blocks with four treatments and ten repetitions with inclusion levels 0, 6, 12 and 18% crude glycerine in dry matter (DM) of the diet. Blood samples were taken for analysis of different biomarkers in the penultimate day of the experiment. significant effects of the inclusion of crude glycerin in place of corn in lambs diet for the different biomarkers of protein profile, mineral and enzyme activity were not registered. When the energy profile, it identified significant effect only for the plasma glucose concentration (p = 0.0003). In regression analysis of plasma glucose concentration lambs, depending on the level of consuming crude glycerine associated with urea replacing corn, it was found that the higher the inclusion of crude glycerin in the diet, increased blood glucose levels (r = 0 , 92, p <.0001). The increasing amount of crude glycerin in the diet of lambs growing replacing corn has gliconeogênico character, and that does not cause metabolic changes of parameters related to energy profile, protein, mineral and enzyme activity. The crude glycerin can be provided up to 18% for maintaining the fuel efficiency and promote good metabolic response. / Um surto de ataxia enzoótica em cordeiros foi registrado no município de Garanhuns, região agreste do estado de Pernambuco, acometendo 18 ovinos (17 fêmeas e um macho). Os animais eram criados em sistema extensivo, sem fornecimento regular na suplementação mineral, alimentados com capim Brachiaria sp. e capim pangola (Digitaria decumbens) além de água à vontade. Os ovinos foram submetidos à avaliação clínica, exames laboratoriais e anatomopatológicos. O quadro clínico dos animais variou de uma semana a 15 dias, entre os sinais merecem destaque a apatia, anorexia, emagrecimento, anemia, mudança de coloração da lã, amaurose, incoordenação dos membros pélvicos, dificuldade na locomoção com fraqueza dos membros posteriores, posição de “cão sentado”, diminuição da resposta sensitiva e motora, quedas frequentes e dificuldade para ficar em estação e episódios de diarreia. Os valores séricos obtidos de Cu foi de (6,88±4,31 μmol/L), abaixo dos valores de referência (9-15 μmol/L), a concentração de Mo (≤0,05 μmol/L), enquanto a de Fe foi de (44,02±28,51 μmol/L) e Zn foi de (16,13±7,87 μmol/L), estavam dentro da faixa de normalidade para a espécie. Na análise de relação entre Fe, Zn e Cu dos cordeiros acometidos de ataxia enzoótica, evidenciam-se baixa relação negativa entre a concentração sérica de Fe com Cu (r= -0,19) e entre a concentração sérica de Zn com Cu (r= -0,07). Na histopatologia, foram observados vacuolização, presença de esferoides axonais e restos mielínicos, sendo estes fagocitados por macrófagos com citoplasma espumoso, além de discreta desmielinização da substância branca. A carência primária de Cu acarreta a ocorrência da AE na região Agreste Meridional do estado de Pernambuco, visto que a deficiência foi em consequência à insuficiente ingestão deste elemento traço pela dieta e não pela ação de antagonistas como o Fe, Zn e Mo. Além disto, a carência de Cu em ovinos criados na região agreste de Pernambuco é tema importante a ser considerada na nutrição mineral, devendo ser recomendado a suplementação adequada de Cu. Objetivou-se avaliar os efeitos da inclusão de glicerina bruta contendo 80,5% de glicerol sobre os parâmetros sanguíneos de cordeiros em confinamento. Utilizaram-se 39 cordeiros mestiços, sem padrão de raça definido, machos não castrados, com quatro meses de idade e peso corporal inicial de 21 kg ± 0,8 Kg, distribuídos em blocos casualizado à quatro tratamentos e dez repetições com níveis de inclusão de 0, 6, 12 e 18% de glicerina bruta na matéria seca (MS) da dieta. Coletas de sangue foram realizadas para análise de diferentes biomarcadores no penúltimo dia de experimento. Não foram registrados efeitos significativos da inclusão de glicerina bruta em substituição do milho na dieta de cordeiros em relação aos diferentes biomarcadores do perfil proteico, mineral e da atividade enzimática. Quando ao perfil energético, identificou-se efeito significativo apenas para a concentração plasmática de glicose (p=0,0003). Na análise de regressão da concentração de glicose plasmática de cordeiros, em função do nível de consumindo de glicerina bruta associada à ureia em substituição ao milho, verificou-se que quanto maior a inclusão de glicerina bruta na dieta, maior a glicemia (r =0,92; p<0001). A quantidade crescente de glicerina bruta na dieta de cordeiros em crescimento em substituição ao milho tem caráter gliconeogênico, além de que não provoca alteração metabólica de parâmetros relacionados ao perfil energético, proteico, mineral e de atividade enzimática. A glicerina bruta pode ser fornecida até 18% por manter a eficiência de consumo e promover boa resposta metabólica.

A hipomielinização ou leucodistrofia hipomielinizante caracteriza-se por diminuição da produção de mielina e consequente redução significativa e permanente de seu depósito na substância branca cerebral. A ressonância magnética (RM) de encéfalo é essencial para o diagnóstico e revela hipersinal leve a moderado na imagem pesada em T2 e sinal variável na imagem pesada em T1, na dependência da quantidade de mielina formada. Para crianças abaixo de 2 anos de idade, mais de um estudo por RM pode ser necessário para confirmar a ausência de mielinização. As leucodistrofias hipomielinizantes clássicas são: a doença de Pelizaeus-Merzbacher (PMD), a doença de Pelizaeus-Merzbacher símile (PMLD), a síndrome de Cockayne, a síndrome 18q-, e mais recentemente descritas, a hipomielinização com catarata congênita (HCC), a hipomielinização com atrofia dos núcleos da base e cerebelo e a hipomielinização com hipodontia e hipogonadismo hipogonadotrófico (síndrome 4H). O objetivo desta tese foi descrever aspectos clínicos, eletrofisiológicos e de neuroimagem em pacientes com hipomielinização. Vinte e cinco pacientes foram incluídos no estudo, apresentando os seguintes diagnósticos: PMD (5), PMLD (5), HCC (1), síndrome de Cockayne (4), síndrome 18q- (1) e leucodistrofias hipomielinizantes não classificadas (4). A avaliação clínica e por RM foi realizada em todos os pacientes e a maioria destes foram submetidos aos estudos eletrofisiológicos com eletroencefalograma (88%), estudo de neurocondução (84%) e potenciais evocados (84%). Vinte e duas famílias foram envolvidas, com consanguinidade reconhecida em quatro delas. A idade variou de 5-21 anos e o sexo masculino representou 56% da amostra. O quadro neurológico teve início até os 3 anos, habitualmente com nistagmo ou ataxia. Manifestações inespecíficas comumente encontradas foram: curso clínico estático ou lentamente progressivo, atraso do desenvolvimento neuropsicomotor, comprometimento antropométrico, deficiência mental, ataxia, sinais de liberação piramidal, nistagmo e alterações da movimentação ocular. Crises epilépticas e manifestações extrapiramidais foram verificadas com menor frequência. Achados discriminatórios foram: o curso clínico progressivo na síndrome de Cockayne, a piora episódica na síndrome 4H, o nistagmo pendular e o tremor cefálico em PMD e PMLD, os dismorfismos nas síndromes de Cockayne e 18q -, a fotossensibilidade na síndrome de Cockayne, as alterações da dentição e o envolvimento endocrinológico na síndrome 4H. O eletroencefalograma exibiu desorganização difusa da atividade elétrica cerebral em 95% dos pacientes, frequentemente associada à assincronia dos elementos fisiológicos do sono, com ou sem paroxismos epileptiformes. O estudo de neurocondução revelou neuropatia periférica desmielinizante, sensitivo-motora ou puramente motora, em 33% da amostra, incluindo pacientes com HCC, síndrome de Cockayne, síndrome 4H e hipomielinização não classificada. Os potenciais evocados evidenciaram disfunção central das vias visuais (29%), auditivas (57%) e somatossensitivas (67%), sem diferenças entre os grupos. O padrão neurorradiológico de hipomielinização, constante entre os grupos, caracterizou-se por alteração simétrica, difusa, extensa e homogênea da substância branca, com hipersinal em T2 e sinal variável em T1. No entanto, algumas particularidades foram observadas em alguns grupos como: maior mielinização da base em relação ao tegmento da ponte em PMD, em HCC e na síndrome 18q-; maior mielinização do tegmento em relação à base em PMLD; predomínio de mielinização no terço médio ou no esplênio do corpo caloso na síndrome 4H; preservação relativa dos tratos piramidais em PMD e na síndrome 4H; mielinização próxima ao normal no núcleo anterolateral do tálamo em PMD, PMLD e na síndrome 4H; focos de mielinização preservada na síndrome 4H; atrofia moderada a grave no corpo caloso em PMD e PMLD ou em cerebelo e corpo caloso na síndrome 4H; atrofia global acentuada na síndrome de Cockayne e ausência de atrofia na síndrome 18q-. Desta forma, confirmamos a heterogeneidade clínica, eletrofisiológica e de neuroimagem da hipomielinização, com resultados muito similares às descrições originais de cada doença, além de reconhecer padrões clínicos e de neuroimagem específicos para algumas doenças. As principais limitações deste estudo foram o tamanho reduzido da nossa amostra e a ausência de confirmação diagnóstica molecular de alguns pacientes. Com o crescente reconhecimento das leucodistrofias hipomielinizantes, torna-se fundamental a melhor compreensão de sua ampla diversidade etiológica, bem como, de suas diferenças sutis / Hypomyelination or hypomyelinating leukodystrophy is characterized by reduced myelin production, leading to significant and permanent decrease on the amount of myelin on the brain white matter. Brain magnetic resonance imaging (MRI) is essential for its diagnosis and discloses a mild to moderate T2W hypersignal and variable T1W signal, which is dependent on the amount of myelin formed. For children bellow 2 years of age, more than one MRI study might be necessary in order to confirm lack of myelination. Classical hypomyelinating leukodystrophies are: Pelizaeus-Merzbacher disease (PMD), Pelizaeus-Merzbacher-like disease (PMLD), Cockayne syndrome, 18q- syndrome, and the more recently described, hypomyelination and congenital cataract (HCC), hypomyelination with atrophy of the basal ganglia and cerebellum, and hypomyelination with hypodontia and hypogonadotrophic hypogonadism (4H syndrome). The aim of this thesis was to describe clinical, electrophysiological and neuroimaging characteristics of patients with hypomyelination. Twenty-five subjects were included in this study and they presented with the following diagnosis: PMD (5), PMLD (5), HCC (1), Cockayne syndrome (4), 18q- syndrome (1) and unclassified hypomyelinating leukodystrophy (4). Clinical and MRI evaluation were performed in all subjects and most of them were submitted to electrophysiological studies with electroencephalogram (88%), nerve conduction study (84%) and multimodel evoked potentials (84%). Twenty- two families were enrolled and imbreeding was recognized in four of them. The age range was 5 to 21 years and males represented 56% of the sample. The age of onset of neurological symptoms was before 3 years old and was characterized mainly by nystagmus and ataxia. Inespecific manifestations commonly seen were: static or slowly progressive clinical course, neurodevelopmental delay, failure to thrive, mental retardation, ataxia, pyramidal signs, nystagmus and other eye movements abnormalities. Epilepsy and extrapyramidal signs were seldom noticed. Discriminant findings were: progressive clinical decline in Cockayne syndrome, episodic deterioration in 4H syndrome, pendular nystagmus and cephalic tremor in PMD and PMLD, dysmorphisms in Cockayne and 18q- syndromes, photosensitivity in Cockayne syndrome, dentition abnormalities and endocrine involvement in 4H syndrome. Electroencephalogram displayed diffuse disorganization of brain electrical activity in 95% of the patients, frequently associated with asynchrony of sleep physiological elements, with or without epileptiform paroxysms. Nerve conduction study disclosed sensory-motor or purely motor demyelinating peripheral neuropathy in 33% of the sample, including patients with HCC, Cockayne syndrome, 4H syndrome and unclassified hypomyelinating leukodystrophy. Evoked potentials demonstrated central dysfunction of the visual (29%), auditory (57%) and somatosensory (67%) pathways, without discrimination among the groups. Hypomyelination pattern on brain MRI was constant among the groups and was characterized by symmetrical, diffuse, extensive and homogeneous abnormal white matter, displayed by T2W hypersignal and variable T1W signal. Nevertheless, some particular findings were observed in some groups: increased myelination of basilar portion of pons compared to the tegmental region in PMD, HCC and 18q- syndrome; increased tegmental myelination compared to the basilar portion of pons in PMLD; predominant myelination of corpus callosum truncus and splenium in 4H syndrome; relative sparing of pyramidal tract in PMD and 4H syndrome; close to normal myelination in anterolateral nucleus of the thalamus in PMD, PMLD and 4H syndrome; focal areas of preserved myelination in 4H syndrome; moderate to severe atrophy of corpus callosum in PMD and PMLD, and of cerebellum and corpus callosum in 4H syndrome; global and pronounced brain atrophy in Cockayne syndrome, and no brain atrophy in 18q- syndrome. We were able to confirm the clinical, electrophysiological and neuroimaging heterogeneity in hypomyelination, with findings similar to those of the original descriptions, and to recognize specific clinical and neuroimaging patterns in some conditions. The main limitations of this study were the small size of our sample and the absence of molecular confirmation of diagnosis in some of the patients. As hypomyelinating leukodystrophy is being recognized with increasing frequency, it is imperative to have a better understanding of their broad etiologic diversity and their subtle differences

Friedreich’s ataxia (FRDA) is an autosomal recessive inherited disorder affecting approximately 1 every 40,000 individuals in Western Europe, is characterized by progressive gait and limb ataxia, dysarthria, areflexia, loss of vibratory and position sense, and a progressive weakness of central origin. Additional features particularly include an hypertrophic cardiomyopathy that can cause premature death. A large GAA repeat expansion in the first intron of the FXN gene is the most common mutation underlying FRDA. Patients show severely reduced levels of the FXN-encoded mitochondrial protein frataxin.<p>Frataxin function is not yet completely elucidated. In frataxin deficiency conditions abnormalities of iron metabolism occur: decreased activities of iron-sulfur cluster (ISC) containing proteins, accumulation of iron in mitochondria and depletion in the cytosol, enhanced cellular iron uptake, and, in some models, reduced heme synthesis. <p>Evidence of oxidative stress has also been found in most though not all models of frataxin deficiency. Accordingly, yfh1-deficient yeast and cells from FRDA patients are highly sensitive to oxidants. Respiratory chain dysfunction further aggravate oxidative stress by increasing leakage of electrons and the formation of superoxide. Frataxin deficient cells not only generate more free radicals, but, they also show a reduced ability to mobilize antioxidant defenses, in particular to induce superoxide dismutase 2 (SOD2).<p>Peroxisome proliferator-activated receptor (PPAR) isoform-gamma play a key role in numerous cellular functions and is a key regulator of mitochondrial biogenesis and of the ROS metabolism. Recruitment of the PPAR coactivator-1a (PGC-1a) mediates many effects of the PPAR-γ activation.<p>In a first work we assessed the potential beneficial effects of a potent PPAR-gamma agonist on frataxin expression in primary fibroblasts from healthy controls and FRDA patients, and Neuroblastoma cells. We used the APAF molecule (1-0-hexadecyl-2-azelaoyl-sn-glycero-3-phosphocoline; C33H66NO9P). Our results show that this compound is able to increase frataxin amount both at transcriptional and post-transcriptional level. At a dose of 20µM frataxin mRNA significantly increases in both controls (p=0.03) and FRDA patients (p=0.002) fibroblasts (1). The finding was confirmed in Neuroblastoma cells (p=0.042). According to previous publications APAF, as others PPAR-gamma agonists is able to up-regulate PGC-1a transcription.<p>In a second part of the study we investigate the role of the PPAR-gamma/PGC-1a pathway in the pathogenesis of FRDA. We performed a microarray analysis of heart and skeletal muscle in a mouse model of frataxin deficiency and we found molecular evidence of increased lipogenesis in skeletal muscle and alteration of fiber-type composition in heart, consistent with insulin resistance and cardiomyopathy, respectively. Since the PPAR-gamma pathway is known to regulate both processes, we hypothesized that dysregulation of this pathway could play a key role in frataxin deficiency. We confirmed this by showing a coordinate dysregulation of Pgc1a and the transcription factor Srebp1 in cellular and animal models of frataxin deficiency, and in cells from FRDA patients, who have marked insulin resistance. Particularly, PGC-1a was found significantly reduced (2) in primary fibroblasts and lymphocytes from FRDA patients (p<0.05). Furthermore, PGC-1a mRNA levels strongly correlate with frataxin relative mRNA levels (r2=0.9, p<0.001). According to this observation, in C2C12 myoblasts, PGC-1a and a reporter gene under the control of the PGC-1a promoter are rapidly down-regulated (p<0.05) when frataxin expression is inhibited by an shRNA in vitro. To further investigate this relation, we then generate PGC-1a deficient fibroblasts cells using a specific siRNA; at 72 hours of transfection frataxin was found down-regulate (p<0.05) in control cells. <p>Taken together those data indicate that some mechanism directly links an early effect of frataxin deficiency with reduced PGC-1a transcription in this cell type, and presumably in other cells that also down-regulate PGC-1α when frataxin levels are low.<p>Finally, since PGC-1a has also emerged as a key factor in the induction of many antioxidant programs in response to oxidative stress, both in vivo and in vitro, in particular in neurons, we tested whether the PGC-1a down-regulation occurring in FRDA cells could be in part responsible for the blunted antioxidant response observed in frataxin deficiency.<p>Using primary fibroblasts from FRDA patients we found reduced SOD2 levels (p<0.05), according to PGC1& / Doctorat en Sciences biomédicales et pharmaceutiques / info:eu-repo/semantics/nonPublished

Neurodegenerative disorders are heterogenous in nature and include a range of ataxias with oculomotor apraxia, which are characterised by a wide variety of neurological and ophthalmological features. This family includes recessive and dominant disorders. A subfamily of autosomal recessive cerebellar ataxias are characterised by defects in the cellular response to DNA damage. These include the well characterised disorders Ataxia-Telangiectasia (A-T) and Ataxia-Telangiectasia Like Disorder (A-TLD) as well as the recently identified diseases Spinocerebellar ataxia with axonal neuropathy Type 1 (SCAN1), Ataxia with Oculomotor Apraxia Type 2 (AOA2), as well as the subject of this thesis, Ataxia with Oculomotor Apraxia Type 1 (AOA1). AOA1 is caused by mutations in the APTX gene, which is located at chromosomal locus 9p13. This gene codes for the 342 amino acid protein Aprataxin. Mutations in APTX cause destabilization of Aprataxin, thus AOA1 is a result of Aprataxin deficiency. Aprataxin has three functional domains, an N-terminal Forkhead Associated (FHA) phosphoprotein interaction domain, a central Histidine Triad (HIT) nucleotide hydrolase domain and a C-terminal C2H2 zinc finger. Aprataxins FHA domain has homology to FHA domain of the DNA repair protein 5’ polynucleotide kinase 3’ phosphatase (PNKP). PNKP interacts with a range of DNA repair proteins via its FHA domain and plays a critical role in processing damaged DNA termini. The presence of this domain with a nucleotide hydrolase domain and a DNA binding motif implicated that Aprataxin may be involved in DNA repair and that AOA1 may be caused by a DNA repair deficit. This was substantiated by the interaction of Aprataxin with proteins involved in the repair of both single and double strand DNA breaks (XRay Cross-Complementing 1, XRCC4 and Poly-ADP Ribose Polymerase-1) and the hypersensitivity of AOA1 patient cell lines to single and double strand break inducing agents. At the commencement of this study little was known about the in vitro and in vivo properties of Aprataxin. Initially this study focused on generation of recombinant Aprataxin proteins to facilitate examination of the in vitro properties of Aprataxin. Using recombinant Aprataxin proteins I found that Aprataxin binds to double stranded DNA. Consistent with a role for Aprataxin as a DNA repair enzyme, this binding is not sequence specific. I also report that the HIT domain of Aprataxin hydrolyses adenosine derivatives and interestingly found that this activity is competitively inhibited by DNA. This provided initial evidence that DNA binds to the HIT domain of Aprataxin. The interaction of DNA with the nucleotide hydrolase domain of Aprataxin provided initial evidence that Aprataxin may be a DNA-processing factor. Following these studies, Aprataxin was found to hydrolyse 5’adenylated DNA, which can be generated by unscheduled ligation at DNA breaks with non-standard termini. I found that cell extracts from AOA1 patients do not have DNA-adenylate hydrolase activity indicating that Aprataxin is the only DNA-adenylate hydrolase in mammalian cells. I further characterised this activity by examining the contribution of the zinc finger and FHA domains to DNA-adenylate hydrolysis by the HIT domain. I found that deletion of the zinc finger ablated the activity of the HIT domain against adenylated DNA, indicating that the zinc finger may be required for the formation of a stable enzyme-substrate complex. Deletion of the FHA domain stimulated DNA-adenylate hydrolysis, which indicated that the activity of the HIT domain may be regulated by the FHA domain. Given that the FHA domain is involved in protein-protein interactions I propose that the activity of Aprataxins HIT domain may be regulated by proteins which interact with its FHA domain. We examined this possibility by measuring the DNA-adenylate hydrolase activity of extracts from cells deficient for the Aprataxin-interacting DNA repair proteins XRCC1 and PARP-1. XRCC1 deficiency did not affect Aprataxin activity but I found that Aprataxin is destabilized in the absence of PARP-1, resulting in a deficiency of DNA-adenylate hydrolase activity in PARP-1 knockout cells. This implies a critical role for PARP-1 in the stabilization of Aprataxin. Conversely I found that PARP-1 is destabilized in the absence of Aprataxin. PARP-1 is a central player in a number of DNA repair mechanisms and this implies that not only do AOA1 cells lack Aprataxin, they may also have defects in PARP-1 dependant cellular functions. Based on this I identified a defect in a PARP-1 dependant DNA repair mechanism in AOA1 cells. Additionally, I identified elevated levels of oxidized DNA in AOA1 cells, which is indicative of a defect in Base Excision Repair (BER). I attribute this to the reduced level of the BER protein Apurinic Endonuclease 1 (APE1) I identified in Aprataxin deficient cells. This study has identified and characterised multiple DNA repair defects in AOA1 cells, indicating that Aprataxin deficiency has far-reaching cellular consequences. Consistent with the literature, I show that Aprataxin is a nuclear protein with nucleoplasmic and nucleolar distribution. Previous studies have shown that Aprataxin interacts with the nucleolar rRNA processing factor nucleolin and that AOA1 cells appear to have a mild defect in rRNA synthesis. Given the nucleolar localization of Aprataxin I examined the protein-protein interactions of Aprataxin and found that Aprataxin interacts with a number of rRNA transcription and processing factors. Based on this and the nucleolar localization of Aprataxin I proposed that Aprataxin may have an alternative role in the nucleolus. I therefore examined the transcriptional activity of Aprataxin deficient cells using nucleotide analogue incorporation. I found that AOA1 cells do not display a defect in basal levels of RNA synthesis, however they display defective transcriptional responses to DNA damage. In summary, this thesis demonstrates that Aprataxin is a DNA repair enzyme responsible for the repair of adenylated DNA termini and that it is required for stabilization of at least two other DNA repair proteins. Thus not only do AOA1 cells have no Aprataxin protein or activity, they have additional deficiencies in PolyADP Ribose Polymerase-1 and Apurinic Endonuclease 1 dependant DNA repair mechanisms. I additionally demonstrate DNA-damage inducible transcriptional defects in AOA1 cells, indicating that Aprataxin deficiency confers a broad range of cellular defects and highlighting the complexity of the cellular response to DNA damage and the multiple defects which result from Aprataxin deficiency. My detailed characterization of the cellular consequences of Aprataxin deficiency provides an important contribution to our understanding of interlinking DNA repair processes.

Introdução: A doença de Machado-Joseph (DMJ) ou ataxia espinocerebelar tipo 3 (SCA3) é causada por uma expansão de trinucleotídeos CAG no gene ATXN3, que leva à degeneração de múltiplos sistemas neurológicos. Seu curso é invariavelmente progressivo, não havendo tratamento específico. Objetivos: Descrever novos biomarcadores, aspectos não motores e definir quais escalas clínicas devem ser utilizadas como desfechos principais nos futuros ensaios clínicos randomizados (ECR) para a DMJ/SCA3. Além de avaliar se o tratamento com carbonato de lítio é seguro e efetivo em reduzir a progressão desta condição. Métodos: Em estudo caso-controle avaliamos: 1) a relação dos sintomas depressivos na DMJ/SCA3, pelo inventário de Beck (BDI), com aspectos de gravidade clínica e molecular; 2) alterações no índice de massa corporal (IMC) e sua correlação com aspectos clínico-moleculares e de neuroimagem; e 3) o Sistema Insulina/ IGF-1 (IIS) e o potencial de seus componentes como biomarcadores. Fizemos uma revisão sistemática sobre os aspectos psicométricos das escalas clínicas de SCAs já descritas, para em seguida iniciarmos um ECR, duplo-cego, paralelo, placebo-controlado de fase 2/3. Para este estudo foram randomizados 62 pacientes com diagnóstico molecular prévio de DMJ/SCA3 com marcha independente e ≤ 10 anos de doença (1:1) para tratamento com carbonato de lítio (0.5-0.8mEq/L) ou placebo. Resultados: Os escores do BDI foram mais elevados na DMJ/SCA3 (p= 0.012) e correlacionaram-se significativamente apenas com as escalas SARA (R=0.359, p=0.01) e NESSCA (R=0.412, p=0.003). Os pacientes com DMJ/SCA3 (N=46) apresentaram IMC menor (24.4 ± 4.1) do que os indivíduos controle (N=42, 27.1± 4.5, p=0.01), havendo correlação inversa (R=−0.396, p=0.015) entre o IMC e o tamanho da sequencia repetitiva CAG (CAGn). Encontramos uma maior sensibilidade periférica à insulina (HOMA2-%S, p=0.003, corrigido pelo IMC) e níveis séricos mais elevados da proteína ligante do IGF-1, IGFBP-1 (p=0.001) na DMJ/SCA3. A IGFBP1 correlacionou-se diretamente à CAGn (R=0.452; p = 0.006) e a sensibilidade à insulina inversamente à idade de início dos sintomas (R=-0.444; P = 0.003). Concluímos, na revisão sistemática, que as escalas semi-quantitativas SARA e NESSCA, e as quantitativas SCAFI e CCFS seriam os melhores desfechos para um ECR. O uso de lítio foi seguro após 24 semanas de tratamento, não havendo diferenças no número total de eventos adversos entre os grupos lítio (50,3%) e placebo (49,7%, p=1.00). O grupo placebo apresentou maior progressão (que não foi significativa) nos escores NESSCA (0.35 pontos, 95% IC -1.0 a 1.7, p=0.222, desfecho primário de efetividade) e SARA (0.96 pontos, 95% IC -0.46 a 2.38, p=0.329), após 48 semanas de tratamento. A gravidade da ataxia de marcha (p=0.008), as provas funcionais quantitativas: PATA rate (p=0.002) e Click Test ND (p=0.023), e os escores compostos SCAFI (p=0.015) e CCFS (p=0.029) apresentaram menor progressão no grupo tratado com lítio durante as 48 semanas. Conclusão: Os resultados destes estudos ajudam no entendimento da depressão e alterações nutricionais da DMJ/SCA3 e apontam a IGFBP-1 como biomarcador e a sensibilidade periférica insulínica como modificador do fenótipo. Houve efetividade do tratamento com carbonato de lítio nos desfechos secundários do ECR, sendo necessária confirmação por ensaios clínicos multicêntricos. / Background: Machado-Joseph disease (MJD) or spinocerebellar ataxia type 3 (SCA3) is caused by a CAG repeat expansion at ATXN3 gene, leading to progressive degeneration of multiple neurological systems. MJD/SCA3 is an invariably progressive disorder, with no current treatment. Objectives: To describe new disease biomarkers, non-motor aspects and to define the clinical SCA scales to be utilized as main outcomes in future randomized controlled trials (RCT) on MJD/SCA3. And further assess safety and effectiveness of lithium carbonate in reducing the progression of this condition. Methods: We performed a case-control study to evaluate: 1) the relation of MJD/SCA3 depressive symptoms, through Beck depression Inventory (BDI), with other clinical and molecular findings; 2) the Body Mass Index (BMI) of MJD/SCA3 patients and the correlation with other clinical, molecular and neuroimaging findings; and 3) the Insulin/IGF-1 system (IIS) in MJD/SCA3 and the possible biomarker properties of its components. We further performed a systematic review on the psychometric properties of the described SCAs scales in order to initiate the double-blind, parallel, placebo-controlled phase 2/3 clinical trial. 62 independently ambulatory MJD/SCA3 patients with ≤ 10 years of disease duration were randomly assigned in the RCT (1:1) to lithium (0.5-0.8mEq/L) or placebo. Results: BDI scores were higher in MJD/SCA3 patients (p= 0.012), with significant correlations only with the scales SARA (R=0.359, p=0.01) and NESSCA (R=0.412, p=0.003). MJD/SCA3 patients (N=46) presented lower BMI (24.4 ± 4.1) than control individuals (N=42, 27.1± 4.5, p=0.01). BMI correlated inversely with the length of the expanded CAG repeat (CAGn). We found higher peripheral sensitivity to insulin (HOMA2-%S, p=0.003, corrected for BMI) and serum levels of the IGF-1 binding protein, IGFBP-1 (p=0.001) in MJD/SCA3. IGFBP-1 correlated with CAGn (R=0.452; p = 0.006) and insulin sensitivity with the age of disease onset (R=-0.444; P = 0.003). In the systematic review we concluded that the semiquantitative SCA scales SARA and NESSCA and the quantitative instruments SCAFI and CCFS would be the most appropriate outcomes for the RCT. After 24 weeks, there were no differences in the number of adverse events in lithium (50.3%) and placebo (40.7%) groups (p=1.00) in the RCT. The placebo group presented a non-significant faster progression on NESSCA (0.35 points, 95% CI -1.0 to 1.7, p=0.612, primary effectiveness outcome) and SARA (0.96 points, 95% CI -0.46 to 2.38, p=0.186), after 48 weeks of treatment. Gait ataxia severity (p=0.008), the quantitative performance tasks: PATA rate (p=0.002) and Click Test ND (p=0.023), and the composite scores SCAFI (p=0.015) and CCFS (p=0.029) presented a slower progression under lithium therapy in the overall 48 weeks period. Conclusion: These studies added to the understanding of depressive and nutritional manifestations of MJD/SCA3 and points IGFBP-1 as a biomarker and peripheral insulin sensitivity as a disease phenotype modifier. The effectiveness of lithium carbonate treatment shown in secondary outcomes of the RCT opened a perspective for an effective therapy for this untreatable disorder that must be confirmed by large multicentric clinical trials.

Introdução: A doença de Machado-Joseph (DMJ) ou ataxia espinocerebelar tipo 3 (SCA3) é causada por uma expansão de trinucleotídeos CAG no gene ATXN3, que leva à degeneração de múltiplos sistemas neurológicos. Seu curso é invariavelmente progressivo, não havendo tratamento específico. Objetivos: Descrever novos biomarcadores, aspectos não motores e definir quais escalas clínicas devem ser utilizadas como desfechos principais nos futuros ensaios clínicos randomizados (ECR) para a DMJ/SCA3. Além de avaliar se o tratamento com carbonato de lítio é seguro e efetivo em reduzir a progressão desta condição. Métodos: Em estudo caso-controle avaliamos: 1) a relação dos sintomas depressivos na DMJ/SCA3, pelo inventário de Beck (BDI), com aspectos de gravidade clínica e molecular; 2) alterações no índice de massa corporal (IMC) e sua correlação com aspectos clínico-moleculares e de neuroimagem; e 3) o Sistema Insulina/ IGF-1 (IIS) e o potencial de seus componentes como biomarcadores. Fizemos uma revisão sistemática sobre os aspectos psicométricos das escalas clínicas de SCAs já descritas, para em seguida iniciarmos um ECR, duplo-cego, paralelo, placebo-controlado de fase 2/3. Para este estudo foram randomizados 62 pacientes com diagnóstico molecular prévio de DMJ/SCA3 com marcha independente e ≤ 10 anos de doença (1:1) para tratamento com carbonato de lítio (0.5-0.8mEq/L) ou placebo. Resultados: Os escores do BDI foram mais elevados na DMJ/SCA3 (p= 0.012) e correlacionaram-se significativamente apenas com as escalas SARA (R=0.359, p=0.01) e NESSCA (R=0.412, p=0.003). Os pacientes com DMJ/SCA3 (N=46) apresentaram IMC menor (24.4 ± 4.1) do que os indivíduos controle (N=42, 27.1± 4.5, p=0.01), havendo correlação inversa (R=−0.396, p=0.015) entre o IMC e o tamanho da sequencia repetitiva CAG (CAGn). Encontramos uma maior sensibilidade periférica à insulina (HOMA2-%S, p=0.003, corrigido pelo IMC) e níveis séricos mais elevados da proteína ligante do IGF-1, IGFBP-1 (p=0.001) na DMJ/SCA3. A IGFBP1 correlacionou-se diretamente à CAGn (R=0.452; p = 0.006) e a sensibilidade à insulina inversamente à idade de início dos sintomas (R=-0.444; P = 0.003). Concluímos, na revisão sistemática, que as escalas semi-quantitativas SARA e NESSCA, e as quantitativas SCAFI e CCFS seriam os melhores desfechos para um ECR. O uso de lítio foi seguro após 24 semanas de tratamento, não havendo diferenças no número total de eventos adversos entre os grupos lítio (50,3%) e placebo (49,7%, p=1.00). O grupo placebo apresentou maior progressão (que não foi significativa) nos escores NESSCA (0.35 pontos, 95% IC -1.0 a 1.7, p=0.222, desfecho primário de efetividade) e SARA (0.96 pontos, 95% IC -0.46 a 2.38, p=0.329), após 48 semanas de tratamento. A gravidade da ataxia de marcha (p=0.008), as provas funcionais quantitativas: PATA rate (p=0.002) e Click Test ND (p=0.023), e os escores compostos SCAFI (p=0.015) e CCFS (p=0.029) apresentaram menor progressão no grupo tratado com lítio durante as 48 semanas. Conclusão: Os resultados destes estudos ajudam no entendimento da depressão e alterações nutricionais da DMJ/SCA3 e apontam a IGFBP-1 como biomarcador e a sensibilidade periférica insulínica como modificador do fenótipo. Houve efetividade do tratamento com carbonato de lítio nos desfechos secundários do ECR, sendo necessária confirmação por ensaios clínicos multicêntricos. / Background: Machado-Joseph disease (MJD) or spinocerebellar ataxia type 3 (SCA3) is caused by a CAG repeat expansion at ATXN3 gene, leading to progressive degeneration of multiple neurological systems. MJD/SCA3 is an invariably progressive disorder, with no current treatment. Objectives: To describe new disease biomarkers, non-motor aspects and to define the clinical SCA scales to be utilized as main outcomes in future randomized controlled trials (RCT) on MJD/SCA3. And further assess safety and effectiveness of lithium carbonate in reducing the progression of this condition. Methods: We performed a case-control study to evaluate: 1) the relation of MJD/SCA3 depressive symptoms, through Beck depression Inventory (BDI), with other clinical and molecular findings; 2) the Body Mass Index (BMI) of MJD/SCA3 patients and the correlation with other clinical, molecular and neuroimaging findings; and 3) the Insulin/IGF-1 system (IIS) in MJD/SCA3 and the possible biomarker properties of its components. We further performed a systematic review on the psychometric properties of the described SCAs scales in order to initiate the double-blind, parallel, placebo-controlled phase 2/3 clinical trial. 62 independently ambulatory MJD/SCA3 patients with ≤ 10 years of disease duration were randomly assigned in the RCT (1:1) to lithium (0.5-0.8mEq/L) or placebo. Results: BDI scores were higher in MJD/SCA3 patients (p= 0.012), with significant correlations only with the scales SARA (R=0.359, p=0.01) and NESSCA (R=0.412, p=0.003). MJD/SCA3 patients (N=46) presented lower BMI (24.4 ± 4.1) than control individuals (N=42, 27.1± 4.5, p=0.01). BMI correlated inversely with the length of the expanded CAG repeat (CAGn). We found higher peripheral sensitivity to insulin (HOMA2-%S, p=0.003, corrected for BMI) and serum levels of the IGF-1 binding protein, IGFBP-1 (p=0.001) in MJD/SCA3. IGFBP-1 correlated with CAGn (R=0.452; p = 0.006) and insulin sensitivity with the age of disease onset (R=-0.444; P = 0.003). In the systematic review we concluded that the semiquantitative SCA scales SARA and NESSCA and the quantitative instruments SCAFI and CCFS would be the most appropriate outcomes for the RCT. After 24 weeks, there were no differences in the number of adverse events in lithium (50.3%) and placebo (40.7%) groups (p=1.00) in the RCT. The placebo group presented a non-significant faster progression on NESSCA (0.35 points, 95% CI -1.0 to 1.7, p=0.612, primary effectiveness outcome) and SARA (0.96 points, 95% CI -0.46 to 2.38, p=0.186), after 48 weeks of treatment. Gait ataxia severity (p=0.008), the quantitative performance tasks: PATA rate (p=0.002) and Click Test ND (p=0.023), and the composite scores SCAFI (p=0.015) and CCFS (p=0.029) presented a slower progression under lithium therapy in the overall 48 weeks period. Conclusion: These studies added to the understanding of depressive and nutritional manifestations of MJD/SCA3 and points IGFBP-1 as a biomarker and peripheral insulin sensitivity as a disease phenotype modifier. The effectiveness of lithium carbonate treatment shown in secondary outcomes of the RCT opened a perspective for an effective therapy for this untreatable disorder that must be confirmed by large multicentric clinical trials.

Introdução: A doença de Machado-Joseph (DMJ) ou ataxia espinocerebelar tipo 3 (SCA3) é causada por uma expansão de trinucleotídeos CAG no gene ATXN3, que leva à degeneração de múltiplos sistemas neurológicos. Seu curso é invariavelmente progressivo, não havendo tratamento específico. Objetivos: Descrever novos biomarcadores, aspectos não motores e definir quais escalas clínicas devem ser utilizadas como desfechos principais nos futuros ensaios clínicos randomizados (ECR) para a DMJ/SCA3. Além de avaliar se o tratamento com carbonato de lítio é seguro e efetivo em reduzir a progressão desta condição. Métodos: Em estudo caso-controle avaliamos: 1) a relação dos sintomas depressivos na DMJ/SCA3, pelo inventário de Beck (BDI), com aspectos de gravidade clínica e molecular; 2) alterações no índice de massa corporal (IMC) e sua correlação com aspectos clínico-moleculares e de neuroimagem; e 3) o Sistema Insulina/ IGF-1 (IIS) e o potencial de seus componentes como biomarcadores. Fizemos uma revisão sistemática sobre os aspectos psicométricos das escalas clínicas de SCAs já descritas, para em seguida iniciarmos um ECR, duplo-cego, paralelo, placebo-controlado de fase 2/3. Para este estudo foram randomizados 62 pacientes com diagnóstico molecular prévio de DMJ/SCA3 com marcha independente e ≤ 10 anos de doença (1:1) para tratamento com carbonato de lítio (0.5-0.8mEq/L) ou placebo. Resultados: Os escores do BDI foram mais elevados na DMJ/SCA3 (p= 0.012) e correlacionaram-se significativamente apenas com as escalas SARA (R=0.359, p=0.01) e NESSCA (R=0.412, p=0.003). Os pacientes com DMJ/SCA3 (N=46) apresentaram IMC menor (24.4 ± 4.1) do que os indivíduos controle (N=42, 27.1± 4.5, p=0.01), havendo correlação inversa (R=−0.396, p=0.015) entre o IMC e o tamanho da sequencia repetitiva CAG (CAGn). Encontramos uma maior sensibilidade periférica à insulina (HOMA2-%S, p=0.003, corrigido pelo IMC) e níveis séricos mais elevados da proteína ligante do IGF-1, IGFBP-1 (p=0.001) na DMJ/SCA3. A IGFBP1 correlacionou-se diretamente à CAGn (R=0.452; p = 0.006) e a sensibilidade à insulina inversamente à idade de início dos sintomas (R=-0.444; P = 0.003). Concluímos, na revisão sistemática, que as escalas semi-quantitativas SARA e NESSCA, e as quantitativas SCAFI e CCFS seriam os melhores desfechos para um ECR. O uso de lítio foi seguro após 24 semanas de tratamento, não havendo diferenças no número total de eventos adversos entre os grupos lítio (50,3%) e placebo (49,7%, p=1.00). O grupo placebo apresentou maior progressão (que não foi significativa) nos escores NESSCA (0.35 pontos, 95% IC -1.0 a 1.7, p=0.222, desfecho primário de efetividade) e SARA (0.96 pontos, 95% IC -0.46 a 2.38, p=0.329), após 48 semanas de tratamento. A gravidade da ataxia de marcha (p=0.008), as provas funcionais quantitativas: PATA rate (p=0.002) e Click Test ND (p=0.023), e os escores compostos SCAFI (p=0.015) e CCFS (p=0.029) apresentaram menor progressão no grupo tratado com lítio durante as 48 semanas. Conclusão: Os resultados destes estudos ajudam no entendimento da depressão e alterações nutricionais da DMJ/SCA3 e apontam a IGFBP-1 como biomarcador e a sensibilidade periférica insulínica como modificador do fenótipo. Houve efetividade do tratamento com carbonato de lítio nos desfechos secundários do ECR, sendo necessária confirmação por ensaios clínicos multicêntricos. / Background: Machado-Joseph disease (MJD) or spinocerebellar ataxia type 3 (SCA3) is caused by a CAG repeat expansion at ATXN3 gene, leading to progressive degeneration of multiple neurological systems. MJD/SCA3 is an invariably progressive disorder, with no current treatment. Objectives: To describe new disease biomarkers, non-motor aspects and to define the clinical SCA scales to be utilized as main outcomes in future randomized controlled trials (RCT) on MJD/SCA3. And further assess safety and effectiveness of lithium carbonate in reducing the progression of this condition. Methods: We performed a case-control study to evaluate: 1) the relation of MJD/SCA3 depressive symptoms, through Beck depression Inventory (BDI), with other clinical and molecular findings; 2) the Body Mass Index (BMI) of MJD/SCA3 patients and the correlation with other clinical, molecular and neuroimaging findings; and 3) the Insulin/IGF-1 system (IIS) in MJD/SCA3 and the possible biomarker properties of its components. We further performed a systematic review on the psychometric properties of the described SCAs scales in order to initiate the double-blind, parallel, placebo-controlled phase 2/3 clinical trial. 62 independently ambulatory MJD/SCA3 patients with ≤ 10 years of disease duration were randomly assigned in the RCT (1:1) to lithium (0.5-0.8mEq/L) or placebo. Results: BDI scores were higher in MJD/SCA3 patients (p= 0.012), with significant correlations only with the scales SARA (R=0.359, p=0.01) and NESSCA (R=0.412, p=0.003). MJD/SCA3 patients (N=46) presented lower BMI (24.4 ± 4.1) than control individuals (N=42, 27.1± 4.5, p=0.01). BMI correlated inversely with the length of the expanded CAG repeat (CAGn). We found higher peripheral sensitivity to insulin (HOMA2-%S, p=0.003, corrected for BMI) and serum levels of the IGF-1 binding protein, IGFBP-1 (p=0.001) in MJD/SCA3. IGFBP-1 correlated with CAGn (R=0.452; p = 0.006) and insulin sensitivity with the age of disease onset (R=-0.444; P = 0.003). In the systematic review we concluded that the semiquantitative SCA scales SARA and NESSCA and the quantitative instruments SCAFI and CCFS would be the most appropriate outcomes for the RCT. After 24 weeks, there were no differences in the number of adverse events in lithium (50.3%) and placebo (40.7%) groups (p=1.00) in the RCT. The placebo group presented a non-significant faster progression on NESSCA (0.35 points, 95% CI -1.0 to 1.7, p=0.612, primary effectiveness outcome) and SARA (0.96 points, 95% CI -0.46 to 2.38, p=0.186), after 48 weeks of treatment. Gait ataxia severity (p=0.008), the quantitative performance tasks: PATA rate (p=0.002) and Click Test ND (p=0.023), and the composite scores SCAFI (p=0.015) and CCFS (p=0.029) presented a slower progression under lithium therapy in the overall 48 weeks period. Conclusion: These studies added to the understanding of depressive and nutritional manifestations of MJD/SCA3 and points IGFBP-1 as a biomarker and peripheral insulin sensitivity as a disease phenotype modifier. The effectiveness of lithium carbonate treatment shown in secondary outcomes of the RCT opened a perspective for an effective therapy for this untreatable disorder that must be confirmed by large multicentric clinical trials.

Nous présentons ici la description clinique et génétique d’un syndrome neurocutané unique. Le laboratoire du Dr Cossette a entrepris la caractérisation clinique et génétique d'une famille canadienne-française qui a été identifiée par les Drs Giroux et Barbeau en 1972 et qui comprend plus de 100 personnes sur six générations. Les membres atteints de cette famille présentent des lésions typiques d'érythrokératodermie (EK) (OMIM 133190, EKV1 et EKV2), associées à une ataxie spinocérébelleuse pure. Dans cette famille, l'ataxie est caractérisée par des troubles de la coordination et de la démarche causés par une dégénérescence du cervelet et de la moelle épinière. Cette ataxie est transmise selon un mode autosomique dominant. Une étude antérieure de cette variante d'EK avec ataxie avait suggéré une liaison sur le chromosome 1p34-p35, soit la même région que les formes EKV de type 1 et 2, causées respectivement par des mutations dans les gènes connexin-31 (GJB3; OMIM 603324) et connexin-30.3 (GJB4; OMIM 605425). Cependant, aucune mutation n'a été retrouvée dans ces gènes pour la famille canadienne-française. Nous avons récemment recontacté la famille et effectué des examens détaillés, incluant une imagerie par résonance magnétique (IRM) et un électromyogramme (EMG). Les manifestations neurologiques des individus atteints sont compatibles avec une nouvelle forme d’ataxie cérébelleuse pure à transmission autosomique dominante (ADCA de type III dans la classification de Harding) que nous avons appelée SCA34. Une cartographie complète du génome nous a permis de localiser le gène SCA34 sur le chromosome 6p12.3-q16.2. Également, en collaboration avec les Drs Alexis Brice (Hôpital Pitié-La Salpêtrière, Paris) et Alfredo Brusco (Hôpital San Giovanni Battista di Torino, Italie), nous avons confirmé que trois autres familles européennes avec SCA inexpliquée étaient également liées au locus SCA34. Notre laboratoire a récemment entrepris la recherche des mutations responsables de SCA34. Les résultats de ce criblage de gènes candidats sont présentés dans le chapitre 3 de cette thèse. / We present here the clinical and genetic description of a unique neuro-cutaneous syndrome. Dr. Cossette’s laboratory began the clinical and genetic characterization of a French-Canadian family who was identified by Drs. Giroux and Barbeau in 1972 and includes more than 100 people over six generations. The affected members of this family have typical lesions of erythrokeratodermia (EK) (OMIM 133190, and EKV1 EKV2), associated with pure spinocerebellar ataxia. In this family, the clinical phenotype is characterized by gait ataxia caused by degeneration of the cerebellum and spinal cord and the pattern of inheritance is compatible with an autosomal dominant trait. In a previous study of this variant of ataxia with EK, putative linkage was found on chromosome 1p34-p35, the same chromosomal region of EKV1 and EKV2 that are respectively caused by mutations in the connexin-31 gene (GJB3, OMIM 603324) and connexin -30.3 (GJB4, OMIM 605425). However, no mutations have been found in these latter genes for the French-Canadian family. We recently contacted the family and carried out detailed examinations, including a magnetic resonance imaging (MRI) and electromyography (EMG). Neurological manifestations of affected individuals are consistent with a new form of pure autosomal dominant cerebellar ataxia, (ADCA type III in the classification of Harding) that we named SCA34. A whole genome scan allowed us to map the gene on chromosome 6p12.3-q16.2. Interestingly, in collaboration with Dr. Alexis Brice (Hôpital Pitié-La Salpêtrière, Paris), and Alfredo Brusco (San Giovanni Battista Hospital, Turin, Italy), we found that three additional European families with unexplained SCA were also linked to the SCA34 locus. Our laboratory has recently begun the search for mutations causing SCA34. The results of this screening of candidate genes are presented in Chapter 3 of this thesis.

Introdução: Escorpionismo é um problema de saúde no Brasil e em outras regiões do mundo. Em 2015, no Brasil, foram relatados 74.598 acidentes e 119 mortes. Neste estudo, foram descritos aspectos clínicos, epidemiológicos, laboratoriais e de vulnerabilidade nestes acidentes. Métodos: Trata-se de estudo clínico prospectivo e observacional conduzido no Hospital Municipal de Santarém (HMS), de Abril de 2008 a Janeiro de 2014. Os pacientes incluídos no estudo foram admitidos pelo autor e não representam o total de pacientes internados no HMS. Além disso, foi realizado estudo qualitativo com base teórica no conceito de vulnerabilidade que inclui as dimensões individual, social e programática. Resultados: Foram descritos 58 acidentes, presumivelmente, causados por T. obscurus na Amazônia Brasileira. A maioria dos acidentes ocorreu durante o trabalho, a maioria dos pacientes incluídos era do sexo masculino 39 (67,2%). Os principais locais de picada foram as extremidades (pés e mãos) com uma frequência de 51 (90%). Os pacientes relataram sensação de \"choques elétricos\" que podem durar horas. A grande maioria dos pacientes apresenta quadro clínico compatível com disfunção cerebelar aguda, que pode ter início minutos e durar até dois dias após a ocorrência do acidente. Apresentaram ataxia cerebelar, disdiadococinesia, dismetria, disartria, dislalia, naúseas e vômitos. Além disso, alguns pacientes, aprentaram mioclonias e fasciculações que também podem ser atribuídas à disfunção cerebelar aguda ou talvez à ação direta sobre o músculo esquelético. Seis pacientes apresentaram rabdomiólise e dois injúria renal aguda. O quadro clínico observado na maioria dos pacientes consiste, principalmente, em disfunção cerebelar aguda e manifestações neuromusculares anormais, que não foram descritos em qualquer outra região do mundo. Também foram realizadas 28 entrevistas quanti-qualitativas com pacientes vítimas de acidente escorpiônico, as quais foram submetidas à técnica de análise de discurso. Pacientes eram, em sua maioria, homens que moravam na área rural e que trabalhavam como agricultores e viviam em condições sócio demográficas desfavoráveis. Discussão: As manifestações apresentadas por esses pacientes são compatíveis com disfunção cerebelar aguda que pode ser explicada, provavelmente, porque algumas toxinas de T. obscurus (da região de Santarém), não só tem a capacidade de atravessar rapidamente, em poucos minutos, a barreira hemato-encefálica, mas também devem apresentar elevada afinidade por canais iônicos presentes nas membranas de células do cerebelo. As mioclonias e fasciculações podem ser atribuídas à disfunção muscular ou cerebelar. A vulnerabilidade individual e social foi evidenciada em vários aspectos: pouco conhecimento em relação ao comportamento de escorpiões e também às medidas preventivas, baixa escolaridade (incluindo analfabetismo), baixa qualificação profissional, trabalho informal, condições precárias de vida (falta de água encanada, energia elétrica, esgoto). Em relação à dimensão programática foi constatada dificuldade de acesso aos serviços de saúde e a falta de antiveneno no centro de referência. Portanto, o estudo destaca as particularidades do escorpionismo em Santarém e os aspectos mais importantes da vulnerabilidade destes pacientes / Introduction: Scorpionism is a health problem in Brazil and in another regions of the world. In 2015, in Brazil 74,598 accidents and 119 deaths were reported. In this study, were described clinical, epidemiologic, laboratory and vulnerability aspects of these unique scorpion accidents. Methods: A prospective and observational study was conducted in the MHS, from April, 2008 to January, 2014. Patients included in the study were admitted by the authors and do not represent the total number of hospitalized patients in the MHS. In addition, a qualitative study was conducted with the theoretical basis of the vulnerability concept, that includes individual, social and programmatic dimension. Results: We described 58 accidents presumably caused by T. obscurus in Brazilian Amazonia. Most patients were stung during work activities and the majority was male 39 (67.2%). The main sites of stung were the extremities (feet and hands), with a frequency of 51 (90%).Patients reported a sensation of \"electric shocks\" which could last hours. The vast majority of patients presented a clinical picture compatible with acute cerebellar dysfunction, that started in minutes and could last up to two days after the accident. They presented cerebellar ataxia, dysdiadocokinesia, dysmetry, dysarthria, dyslalia, nausea and vomiting. Also, some patients presented myoclonus and fasciculation which can also be attributed to cerebellar dysfunction or perhaps the result of direct action on skeletal muscle. Six patients had developed rhabdomyolysis and two acute kidney injury. The clinical picture observed in most of our patients consisted mainly from an acute cerebellar dysfunction and abnormal neuromuscular manifestations which is not described in any other region of the world. Twenty-eight quantitative and qualitative interviews with scorpion sting victims. Each patient was submitted to discourse analysis technique. The majority patients were men who live in rural areas, small farmers with unfavorable socio-demographic conditions. Discussion: The manifestations presented by these patients are compatible with acute cerebellar dysfunction which could be explained probably because some toxins from T. obscurus from Santarém region, have not only the capacity to cross quickly, within minutes, the blood-brain and also must have high affinity for ionic channels present in some cerebellar cell membranes. Myoclonus and fasciculation can be attributed to cerebellar or muscle dysfunction. The individual and social vulnerability was demonstrated in several ways: little knowledge about the scorpion behavior and about the preventive measures, low education level (including illiteracy), low-skilled, informal work, precarious living conditions (lack of running water, electricity, basic sanitation). Regarding the programmatic dimension it was found difficult access to health services and lack of antivenom serum in the reference center. Therefore, the study highlights the particularities of scorpionism in Santarem and the most important aspects of vulnerability of these patients