Lafora disease (LD) is an adolescent-onset autosomal recessive progressive myoclonus epilepsy. The main clinical symptoms of the disease are worsening seizures, neurodegeneration and usually death within ten years. No therapeutics or interventions exist for this devastating disease. Mutations in two genes, EPM2A (laforin) and EPM2B (malin) are causative of more than 90 percent of LD. The pathognomonic sign of LD is the presence of abnormal glycogen which precipitates and accumulates into starch-like masses called Lafora bodies (LB). There are two main hypotheses of LB formation. Glycogen is synthesized through the combined activities of glycogen synthase (GS) and branching enzyme (BE). One hypothesis is that LB form due to an overactivation of GS, causing a misbalance between synthesis and branching. Here, malin and laforin regulate levels of GS and other protein(s) involved in glycogen synthesis and when missing, result in their overaccumulation and thus overactivation of synthesis in relation to branching. The second hypothesis is based on evidence of increased phosphorylation of glycogen in LB. In this hypothesis, glycogen becomes abnormal because of the hyperphosphorylation, causing it to precipitate. Laforin is a glycogen phosphatase, and removes phosphate from glycogen. When missing, as in LD, glycogen becomes hyperphosphorylated and forms LB. A role for malin is less clear in this hypothesis. In this thesis, I identify and characterize a third gene, PRDM8, causing an early onset form of LD in a large consanguineous family. I show that it both interacts with laforin and malin and results in their relocation to the nucleus. I also characterize a laforin-interacting protein, Epm2aip1, finding an important role for this previously uncharacterized protein in glycogen metabolism. Epm2aip1-/- mice exhibit hepatic insulin resistance, decreased hepatic glycogen synthesis, increased liver fat, and resistance against obesity in adulthood. Epm2aip1 associates with glycogen synthase (GS), and its absence impairs the allosteric activation of GS by glucose-6-phosphate. Finally, I find that genetically removing PTG, an activator of GS, from mice with Lafora disease results in near-complete disappearance of LB, and resolution of the neurodegeneration and myoclonic epilepsy. This work has revealed a gateway to the treatment of this devastating and fatal disease.

Characterized by excessive myocardial glycogen deposition, cardiac hypertrophy, frequent cardiac arrhythmias and progressive conduction system disease, the PRKAG2 cardiac syndrome stems from a genetic mutation in the γ2-subunit of AMP-activated protein kinase (AMPK). Although functionally diverse, the main role of AMPK is to modulate cardiac metabolism in response to depleted ATP levels. A comprehensive study of the dysfunctional regulation of AMPK activity involved in the progression of the human PRKAG2 cardiac syndrome is hindered by the limitations of in vitro techniques. Positron emission tomography (PET) imaging with the glucose analogue, FDG, offers a quantitative assessment of myocardial glucose uptake non-invasively. The aim of this thesis was to determine the ability of FDG to detect changes in glucose uptake, storage and metabolism in the heart in relation to AMPK activity and provide insights into the mechanism of PRKAG2 cardiac hypertrophy. To achieve this aim, a transgenic AMPK γ2-subunit Arg302Gln mouse model was evaluated with small animal FDG PET with correlation to biochemical assays of cardiac AMPK activity and the glycogen metabolism pathway. Using the vena cava blood input function, FDG myocardial glucose uptake was reliably assessed in mice for the first time with Patlak modeling. Reduced FDG uptake in the Arg302Gln PRKAG2 mouse model suggested a feedback pathway reducing exogenous glucose uptake due to excessive intracellular glycogen stores. Despite an increase in FDG uptake in the skeletal muscle of the PRKAG2 mutant mice following insulin stimulation, there was no change in cardiac uptake, signifying myocardial insulin resistance. Increased reliance on glucose oxidation by TMZ inhibition of fatty acid oxidation reduced glycogen stores, restored cardiac function and eliminated ventricular preexcitation. The observed reduction in mouse myocardial FDG uptake mirrors the reduction previously observed in the human PRKAG2 patients. The potential now exists to evaluate both progression and therapeutic interventions for the PRKAG2 cardiac syndrome with the transgenic mouse model with translation to the affected patients using FDG cardiac imaging.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniversitet, 2006. / Härtill 5 uppsatser.

Heidelberg, Univ., Diss., 2007.

Thesis (M.Sc.)--York University, 2009. Graduate Programme in Higher Education. / Typescript. Includes bibliographical references (leaves 76-87). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:MR51589

Thesis (M.S.)--University of Wisconsin--La Crosse, 2002. / Includes bibliographical references.

Made available in DSpace on 2016-02-05T18:29:39Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-04-30. Added 1 bitstream(s) on 2016-02-05T18:33:41Z : No. of bitstreams: 1 000854430_20160430.pdf: 194642 bytes, checksum: bb81f6467dc8e778046a85b1a3883c0d (MD5) Bitstreams deleted on 2016-05-04T13:08:34Z: 000854430_20160430.pdf,. Added 1 bitstream(s) on 2016-05-04T13:09:35Z : No. of bitstreams: 1 000854430.pdf: 866908 bytes, checksum: 304d39176d6ab7c06503c5a80740a3e6 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / A Deficiência da Enzima Ramificadora de Glicogênio (Glycogen Branching Enzyme Deficiency [GBED] em equinos é uma doença hereditária recessiva fatal, caracterizada principalmente por abortos, natimortos e nascimento de potros fracos. A GBED é causada por uma mutação no gene GBE1. Não existem dados acerca da existência de animais com esta mutação no Brasil. O objetivo deste estudo foi verificar a prevalência de animais portadores do alelo mutante da GBED em cavalos da raça Quarto de Milha utilizados em cinco modalidades esportivas equestres no Brasil. Amostras de sangue e pêlo foram obtidas de 740 animais. Após purificação do DNA, foram realizados as reações de PCR, sequenciamento direto automatizado e análise das sequências. Dos 740 animais testados 59 foram considerados heterozigotos para a mutação responsável pela GBED representando uma frequência de 7,97% na população estudada. As prevalências de heterozigotos foram maiores nas linhagens de apartação (20%) e rédeas (10%), seguidos por tambor/baliza (5%) e conformação (3%), não foram encontrados heterozigotos para a modalidade de corrida. Os resultados demostram que a mutação está presente no rebanho brasileiro de cavalos Quarto de milha, e sugere que a doença (homozigotos recessivos) pode estar presente de forma silenciosa. Portanto a GBED deve ser considerada no diagnóstico diferencial nos casos de abortos e morte neonatal em cavalos da raça Quarto de milha no Brasil, e medidas de prevenção da transmissão da mutação devem ser estabelecidas / The deficiency of glycogen branching enzyme [GBED] in horses is a fatal recessive hereditary disease, mainly characterized by abortions, stillbirths and birth of weak foals. The GBED is caused by a mutation in the gene GBE1. The aim of this study was to determine the prevalence of mutation carriers causing GBED in a population of Quarter horse animals used in five equestrian sports practiced in Brazil. Samples of blood and were obtained from 740 animals. After DNA purification, PCR reactions, automated direct sequencing and sequence analysis were performed. Of the 740 animals tested 59 were considered heterozygous for the mutation responsible for GBED representing a prevalence of 7.97% in the population studied. The prevalences of heterozygotes were higher in cutting (20%) and reining (10%) subgroups, followed by barrel racing (5%) and halter (3%), were not found heterozygous for the racing subgroup. The results demonstrate that the mutation is present in the Quarter horse Brazilian herd, and suggests that the disease (homozygous recessive) may be present without being noticed. So the GBED should be considered in the differential diagnosis in cases of abortion and stillbirths in Brazilian Quarter horses and strategies should be developed to prevent transmission of the mutation

Orientador: Gabriel Hessel / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas / Made available in DSpace on 2018-08-09T01:55:34Z (GMT). No. of bitstreams: 1 Banin_MarciaRegina_M.pdf: 2211563 bytes, checksum: e16e20135efbf828907adc92ed40ba6b (MD5) Previous issue date: 2007 / Resumo: Racional - As doenças de depósito de glicogênio compreendem um grupo de doenças geneticamente determinadas e classificadas em 11 tipos, de acordo com as deficiências enzimáticas identificadas. Há pouca informação sobre a evolução dessas doenças. Objetivos - Descrever as características clínicas e laboratoriais, na admissão e evolução, de pacientes com doença de depósito de glicogênio. Pacientes e métodos ¿ Participaram do estudo 22 pacientes com diagnóstico de glicogenose hepática, sendo 11 (50%) do sexo feminino. O estudo foi descritivo e longitudinal. A ficha de coleta de dados constituiu-se de informações iniciais de: quadro clínico, peso, estatura, índice de massa corporal (IMC) e resultados dos exames laboratoriais (hemograma, enzimas hepáticas, colesterol total e frações, triglicérides, glicemia, ácido úrico, uréia e creatinina). Selecionou-se os momentos 1 (admissão), 3 (12 meses de evolução) e 7 (36 meses de evolução) para coleta dos seguintes dados: peso, estatura, IMC, ácido úrico, glicemia, colesterol e triglicérides. Também, foram comparados os resultados de antropometria e exames bioquímicos dos pacientes em dois momentos: admissão e última consulta. Para as variáveis peso e estatura, calculou-se o Z escore sendo considerado déficit quando o valor se situava abaixo do segundo desvio padrão. A velocidade de crescimento foi calculada a partir da 2ª e 1ª consulta (V1) e a partir da última e penúltima consulta (V2). A taxa de aderência foi determinada pela porcentagem de absenteísmo das consultas da seguinte forma: boa: se absenteísmo menor que 20%; regular: se absenteísmo entre 20% e 40% e ruim: se absenteísmo maior que 40%. Utilizou-se como teste estatístico a análise de variância e os testes de Kruskal-Wallis, Mann-Whintney e Wilcoxon, sendo o nível de significância adotado de 5%. Resultados - A média da idade de início dos sintomas foi de 10,7 meses e do diagnóstico de 28,18 meses. O tempo médio de seguimento foi de 105 meses. As manifestações clínicas iniciais mais freqüentes foram: hepatomegalia em 21 (95%), abdômen protuberante em 19 (86%), face de boneca em 14 (64%), diarréia em 10 (45%) e história de hipoglicemia em 8(36%). Nos exames laboratoriais, observou-se, na maioria dos casos, aumento das enzimas hepáticas, hipercolesterolemia, hipertrigliceridemia e hipoglicemia. Na admissão, o déficit de peso/idade foi de 26% (5/19) e de estatura/idade foi de 35% (7/20). Não houve diferença estatística na comparação do Z escore de peso/idade, estatura/idade, índice de massa corporal e exames laboratoriais na admissão, com 12 e 36 meses. Entre a admissão e a última consulta, observou-se diferença significativa no índice de massa corporal, enzimas hepáticas, glicemia e triglicérides, o que não aconteceu com Z escore de peso/idade, estatura/idade e os exames de ácido úrico e colesterol. A taxa de aderência foi considerada boa em 64% dos pacientes. Na comparação da velocidade de crescimento, observou-se tendência de aumento comparando V1 com V2. Conclusões ¿ Houve demora no encaminhamento ao centro de referência para o diagnóstico das glicogenoses. As manifestações clínicas mais freqüentes foram abdômen protuberante e hepatomegalia e as alterações laboratoriais mais significativas foram a elevação dos triglicérides, colesterol e diminuição da glicemia. Na evolução, não houve diferença nos parâmetros antropométricos, mas uma tendência de melhora de velocidade de crescimento. O tratamento melhorou o desarranjo metabólico / Abstract: Background ¿ Glycogen storage diseases comprise a group of genetic diseases determined and classified into 11 types, according to the identified enzymatic deficiency. There is little information regarding the disease evolution. Aim ¿ Describe clinical and laboratorial characteristics in the admission and evolution of patients with glycogen storage disease. Patients and methods ¿ Twenty-two patients with hepatic glycogen diagnosis participated in the study, 11 (50%) of which were female. The study was descriptive and longitudinal. The collected data file consisted of admission information: clinical features, weight, height, body mass index (BMI) and laboratorial exam results: hemogram, hepatic enzymes, total cholesterol and fractions, triglycerides, glycemia, uric acid, urea and creatin. Afterwards, the following phases were selected: 1 (admission), 3 (12 months of evolution) and 7 (36 months of evolution) for the weight, height, BMI and laboratorial tests: uric acid, glycemia, total cholesterol and triglycerides. The antropometric data, hepatic enzymes and mentioned tests were compared during 2 moments: admission and last appointment of each patient. The score Z was utilized to evaluate the weight and height of patients, considered if the standard deviation was under 2. The growth velocity was calculated among the second and first consult and the last and the penultimate consult. The adherence percentage was determined by the appointment absence percentage: Good: absenteeism minor 20%; regular: absenteeism major 20% and minor 40%; bad: absenteeism major 40%. The statistical tests applied were ANOVA, Kruskal-Wallis, Mann-Whintney, and Wilcoxon. The significance level was 5%. Results - The mean time during the first symptoms was 10,73 months and the mean time up to diagnosis was 28,18 months. The mean time of follow-up was 105 months. The most frequent initial clinical manifestations were: hepatomegaly in 21 (95%), protuberant abdomen in 19 (86%), doll face in 14 (64%), diarrhea in 10 (45%) and history hypoglycemia in 8 (36%). In the admission the deficit of the weight to age was 26% (5/19) and height to age was 35% (7/20), In the initial biochemical tests showed elevation of hepatic enzymes, hypercholesterolemia, hypertriglyceridemia, hypoglycemia. There was no statistical difference among the score Z weight to age, score Z height to age, body mass index and laboratorial tests of admission within 12 and 36 months. Significant differences were observed in BMI, hepatic enzymes, glycemia and triglycerides between the first and the last appointments, opposing to the score Z weight to age, score Z height to age, uric acid and cholesterol exam results. In the comparison of the growth velocity there was elevation tendency between the V1 and V2. There was difference significative of the growth velocity among the first and second versus the penultimate and the last consult. The adherence percentage was considered good in 64%. Conclusions - The patients delayed in seeking the reference center for glycogenosis early diagnosis. The most frequent clinical manifestations were protuberant abdomen, hepatomegaly, elevation of triglycerides and cholesterol, and glycemia reduction. In the evolution, there wasn¿t difference statistic in the antropometric parameters, but there was improvement tendency on the growth velocity. The treatment has improved the metabolic derangement / Mestrado / Saude da Criança e do Adolescente / Mestre em Saude da Criança e do Adolescente

Characterized by excessive myocardial glycogen deposition, cardiac hypertrophy, frequent cardiac arrhythmias and progressive conduction system disease, the PRKAG2 cardiac syndrome stems from a genetic mutation in the γ2-subunit of AMP-activated protein kinase (AMPK). Although functionally diverse, the main role of AMPK is to modulate cardiac metabolism in response to depleted ATP levels. A comprehensive study of the dysfunctional regulation of AMPK activity involved in the progression of the human PRKAG2 cardiac syndrome is hindered by the limitations of in vitro techniques. Positron emission tomography (PET) imaging with the glucose analogue, FDG, offers a quantitative assessment of myocardial glucose uptake non-invasively. The aim of this thesis was to determine the ability of FDG to detect changes in glucose uptake, storage and metabolism in the heart in relation to AMPK activity and provide insights into the mechanism of PRKAG2 cardiac hypertrophy. To achieve this aim, a transgenic AMPK γ2-subunit Arg302Gln mouse model was evaluated with small animal FDG PET with correlation to biochemical assays of cardiac AMPK activity and the glycogen metabolism pathway. Using the vena cava blood input function, FDG myocardial glucose uptake was reliably assessed in mice for the first time with Patlak modeling. Reduced FDG uptake in the Arg302Gln PRKAG2 mouse model suggested a feedback pathway reducing exogenous glucose uptake due to excessive intracellular glycogen stores. Despite an increase in FDG uptake in the skeletal muscle of the PRKAG2 mutant mice following insulin stimulation, there was no change in cardiac uptake, signifying myocardial insulin resistance. Increased reliance on glucose oxidation by TMZ inhibition of fatty acid oxidation reduced glycogen stores, restored cardiac function and eliminated ventricular preexcitation. The observed reduction in mouse myocardial FDG uptake mirrors the reduction previously observed in the human PRKAG2 patients. The potential now exists to evaluate both progression and therapeutic interventions for the PRKAG2 cardiac syndrome with the transgenic mouse model with translation to the affected patients using FDG cardiac imaging.

No description available.