Made available in DSpace on 2014-06-12T15:50:41Z (GMT). No. of bitstreams: 1 license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2009 / A esquistossomose mansônica, doença causada pelo helminto Schistosoma mansoni afeta cerca de 200 milhões de pessoas em todo o mundo. Decorrente da deposição de ovos do parasita no fígado, a doença pode evoluir da forma mais leve, hepatointestinal (HI), para a mais grave, hepatoesplênica (HEC). Estudos anteriores demonstram uma relação entre o metabolismo lipídico e a forma hepatoesplênica da parasitose, tais como: diminuição dos níveis plasmático de colesterol total, colesterol esterificado e triglicerídeos, aumento dos níveis de fosfolipídeos em pacientes e em primatas não humanos da espécie Callithrix jacchus e alterações na atividade da lecitina: colesterol aciltransferase (LCAT). A LCAT, enzima esterificante do colesterol, é uma glicoproteína sintetizada pelo fígado e exerce importante papel no metabolismo das lipoproteínas plasmática, especialmente na síntese e maturação das HDL circulantes. Neste trabalho, foi avaliada a concentração plasmática e a atividade da LCAT, bem como o perfil lipídico dos pacientes portadores da esquistossomose mansônica nas fases HI e HEC. Os resultados demonstram, em comparação aos indivíduos saudáveis, uma redução significativa nos níveis de colesterol total, colesterol HDL e colesterol éster, bem como na atividade e na concentração da LCAT em pacientes na fase mais crítica da doença. Esta diminuição da atividade catalítica da enzima pode estar associada à redução na síntese e/ou secreção da enzima, uma vez que a LCAT é produzida no fígado, o qual é bastante afetado na esquistossomose. Os resultados sugerem uma correlação direta entre a concentração da enzima LCAT e sua atividade

Little research has focused on the relationship between lecithin:cholesterol acyltransferase (LCAT) activity and cholesterol metabolism in dogs and cats. To study weight loss and cholesterol metabolism in dogs, four experimental weight-loss diets were fed to 12 obese female beagles for 8 wk in a partial crossover design (n = 6). High- (HGI) or low-glycemic index (LGI) starch and diacylglycerol or triacylglycerol oil were combined to compose diets with similar fatty acid (FA) profiles. Body weight was measured weekly. Fasted blood samples were drawn at wk1, wk4, and wk8 to measure plasma total (TC), unesterified (UC), and esterified cholesterol (EC) concentrations, LCAT activity, and FA composition of the phospholipid (PL) and EC fractions. All groups lost weight. UC increased from wk1 to wk4 (p < 0.05). LCAT activity increased from wk1 to wk4 and remained elevated at wk8 (p < 0.05). Plasma PL FA profiles reflected the diets fed with few diet or time effects. Plasma EC FA profiles reflected the specificity of LCAT for linoleic acid (LA) with minimal diet or time effects. We conclude that weight reduction in dogs occurs in conjunction with increased LCAT activity and altered plasma cholesterol fractions but not changes in plasma PL or EC FA profiles. To measure the activity and demonstrate the FA specificity of LCAT in felines fed varying types of fat, 29 female cats were fed diets enriched with high-oleic sunflower (n = 9), menhaden fish (n = 10), or safflower (n = 10) oil (8g oil/100g kibble) for 4 wk. Fasted blood samples were drawn at d0, d14, and d28 for determination of the blood parameters mentioned previously. LCAT and TC showed no time or diet effects. UC decreased at d28 compared to d0 and d14, while EC increased at d28 compared to d0 and d14 (all p < 0.05). Plasma EC FA profiles reflected the specificity of LCAT for LA with many diet and time effects but contained no docosahexanoic acid (DHA). We conclude that feline LCAT has no measurable affinity for DHA, but both feline and canine LCAT demonstrated specificity for LA regardless of diet fed.

Made available in DSpace on 2014-06-12T15:54:38Z (GMT). No. of bitstreams: 2 arquivo4925_1.pdf: 508056 bytes, checksum: 85e981daa9d6d714824f51e4073a3195 (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2002 / A esquistossomose mansônica apresenta ciclo de infecção, tratamento e reinfecção. A Forma clínica severa da doença promove danos teciduais que afetam órgãos vitais como o fígado e podem levar a alterações no metabolismo lipídico. Neste trabalho, foram avaliadas em Callithrix jacchus as alterações decorrentes de uma segunda infecção após 60 dias da primeira por infestação com 400 cercárias de Schistosoma mansoni. Os níveis de colesterol total, colesterol éster, fosfolipídio total e triglicerídeos foram determinados por método colorimétrico, enquanto o colesterol esterificado formado in vitro pela ação da lecitina: colesterol aciltransferase (LCAT) foi determinado utilizando substrato radioativo contendo [14C]colesterol. Os resultados mostraram redução significativa nos níveis de lipídeos neutros, colesterol total e triglicerídeos, bem como de fosfolipídio total em animais infectados, sendo esta redução significativamente mais acentuada em plasma de animais submetidos à segunda infecção. Similarmente a atividade da LCAT foi significativamente reduzida, após a primeira infecção ocorreu 25% de diminuição na atividade fracional da LCAT em comparação aos animais controles, sendo esta redução ainda maior após a reinfecção (39%). Os resultados indicam que a segunda infecção por S. mansoni promove alterações lipídicas plasmáticas mais acentuadas do que aquelas provenientes da primeira infecção

Lecithin:cholesterol acyltransferase (LCAT) was isolated from hog plasma and basic physicochemical properties and functionally important regions were investigated. Approximately one milligram of the enzyme was purified to apparent homogeneity with approximately a 20,000-fold increase in specific activity. In the plasma, hog LCAT was found to associate with high-density lipoproteins (HDL) probably through hydrophobic interactions with apolipoprotein A-I. HDL was the preferred lipoprotein substrate of the enzyme as its macromolecular substrate. The enzyme was found to contain 4 free sulfhydryl groups; at least one of these appeared to be essential for catalytic activity. The enzyme had a tendency to aggregate at high concentrations. More than half of the tryptophan and none of the tyrosine residues of the enzyme were shown to be exposed to the aqueous environment based on fluorescence and absorbance studies, respectively.

No description available.

Le déficit familial de LCAT (FLD) est une maladie caractérisée par un défaut de l’activité de l’enzyme lecithin:cholesterol acyltransferase (LCAT). Ce défaut résulte en une concentration plasmatique de C-HDL extrêmement basse, des opacités cornéennes prématurées, la présence d’anémie, de protéinurie et d’insuffisance rénale. Nous avons identifié les premiers patients canadiens-français atteints de déficit familial de LCAT. Deux frères, présentant les signes classiques de FLD étaient homozygotes pour une nouvelle mutation du gène de la LCAT: la mutation c.102delG. Cette mutation se traduit au niveau protéique par un changement du cadre de lecture au niveau du codon His35 et l’insertion d’un codon stop en position 61 entraînant une abolition de l’activité LCAT in vitro et in vivo. La présence de cette mutation cause une réduction importante du C-HDL chez les hétérozygotes (22%) et les homozygotes (88%) ainsi qu’une baisse du C-LDL chez les hétérozygotes (35%) et les homozygotes (58%). De plus, le profil lipidique différait de manière importante entre les deux frères atteints de FLD qui présentaient des génotypes APOE différents. Nous suggérons que APOE est un gène qui modifie le phénotype du FLD et pourrait expliquer l’hétérogénéité des profils lipidiques chez les patients atteints de FLD. Nos résultats suggèrent également que l’association du génotype LCAT-/- a un allèle APOE ε2 est un nouveau mécanisme conduisant à la dysbétalipoproteinemie. Finalement nous avons montré des différences importantes dans les sous-populations des HDL chez les deux sujets atteints de FLD. Le porteur de l’allèle APOE ε2 présentait une proportion beaucoup plus importante de HDL immatures (preβ discoïdaux) par rapport a son frère (77.9% vs. 31.0%). / Familial LCAT deficiency (FLD) is a disease characterized by a defect in the enzyme lecithin:cholesterol acyltransferase (LCAT) resulting in low HDL-C, premature corneal opacities, anaemia as well as proteinuria and renal failure. We have identified the first French Canadian kindred with familial LCAT deficiency. Two brothers, presenting classical signs of FLD, were shown to be homozygous for a novel LCAT mutation. This c.102delG mutation occurs at the codon for His35 and causes a frameshift that stops transcription at codon 61 abolishing LCAT enzymatic activity both in vivo and in vitro. It has a dramatic effect on the lipoprotein profile, with an important reduction of HDL-C in both heterozygotes (22%) and homozygotes (88%) and a significant decrease in LDL-C in heterozygotes (35%) as well as homozygotes (58%). Furthermore, the lipoprotein profile differs markedly between the two affected brothers who had different APOE genotypes. We propose that APOE could be an important modifier gene explaining heterogeneity in lipoprotein profiles observed among FLD patients. Our results suggest that a LCAT-/- genotype associated with an APOE ε2 allele could be a novel mechanism leading to dysbetalipoproteinemia. Finally we have identified major differences in the HDL sub-populations of both subjects affected by FLD. The carrier of the APOE ε2 allele presented a much higher proportion of immature HDL particles (discoid preβ) compared to his brother (77.9% vs. 31.0%).

Le déficit familial de LCAT (FLD) est une maladie caractérisée par un défaut de l’activité de l’enzyme lecithin:cholesterol acyltransferase (LCAT). Ce défaut résulte en une concentration plasmatique de C-HDL extrêmement basse, des opacités cornéennes prématurées, la présence d’anémie, de protéinurie et d’insuffisance rénale. Nous avons identifié les premiers patients canadiens-français atteints de déficit familial de LCAT. Deux frères, présentant les signes classiques de FLD étaient homozygotes pour une nouvelle mutation du gène de la LCAT: la mutation c.102delG. Cette mutation se traduit au niveau protéique par un changement du cadre de lecture au niveau du codon His35 et l’insertion d’un codon stop en position 61 entraînant une abolition de l’activité LCAT in vitro et in vivo. La présence de cette mutation cause une réduction importante du C-HDL chez les hétérozygotes (22%) et les homozygotes (88%) ainsi qu’une baisse du C-LDL chez les hétérozygotes (35%) et les homozygotes (58%). De plus, le profil lipidique différait de manière importante entre les deux frères atteints de FLD qui présentaient des génotypes APOE différents. Nous suggérons que APOE est un gène qui modifie le phénotype du FLD et pourrait expliquer l’hétérogénéité des profils lipidiques chez les patients atteints de FLD. Nos résultats suggèrent également que l’association du génotype LCAT-/- a un allèle APOE ε2 est un nouveau mécanisme conduisant à la dysbétalipoproteinemie. Finalement nous avons montré des différences importantes dans les sous-populations des HDL chez les deux sujets atteints de FLD. Le porteur de l’allèle APOE ε2 présentait une proportion beaucoup plus importante de HDL immatures (preβ discoïdaux) par rapport a son frère (77.9% vs. 31.0%). / Familial LCAT deficiency (FLD) is a disease characterized by a defect in the enzyme lecithin:cholesterol acyltransferase (LCAT) resulting in low HDL-C, premature corneal opacities, anaemia as well as proteinuria and renal failure. We have identified the first French Canadian kindred with familial LCAT deficiency. Two brothers, presenting classical signs of FLD, were shown to be homozygous for a novel LCAT mutation. This c.102delG mutation occurs at the codon for His35 and causes a frameshift that stops transcription at codon 61 abolishing LCAT enzymatic activity both in vivo and in vitro. It has a dramatic effect on the lipoprotein profile, with an important reduction of HDL-C in both heterozygotes (22%) and homozygotes (88%) and a significant decrease in LDL-C in heterozygotes (35%) as well as homozygotes (58%). Furthermore, the lipoprotein profile differs markedly between the two affected brothers who had different APOE genotypes. We propose that APOE could be an important modifier gene explaining heterogeneity in lipoprotein profiles observed among FLD patients. Our results suggest that a LCAT-/- genotype associated with an APOE ε2 allele could be a novel mechanism leading to dysbetalipoproteinemia. Finally we have identified major differences in the HDL sub-populations of both subjects affected by FLD. The carrier of the APOE ε2 allele presented a much higher proportion of immature HDL particles (discoid preβ) compared to his brother (77.9% vs. 31.0%).

Submitted by Ana Maria Fiscina Sampaio (fiscina@bahia.fiocruz.br) on 2016-02-15T14:03:58Z No. of bitstreams: 1 Juliana Stolze Efeito...2015.pdf: 1337321 bytes, checksum: 6fdad9cde6d0cc06bd37fdbe677450ae (MD5) / Approved for entry into archive by Ana Maria Fiscina Sampaio (fiscina@bahia.fiocruz.br) on 2016-02-15T14:04:13Z (GMT) No. of bitstreams: 1 Juliana Stolze Efeito...2015.pdf: 1337321 bytes, checksum: 6fdad9cde6d0cc06bd37fdbe677450ae (MD5) / Made available in DSpace on 2016-02-15T14:04:13Z (GMT). No. of bitstreams: 1 Juliana Stolze Efeito...2015.pdf: 1337321 bytes, checksum: 6fdad9cde6d0cc06bd37fdbe677450ae (MD5) Previous issue date: 2015 / Fundação Oswaldo Cruz, Centro de Pesquisas Gonçalo Moniz. Salvador, BA, Brasil / Introdução: as doenças cardiovasculares acometem milhares de pessoas no mundo. Destas, a doença arterosclerótica está entre as de maior morbimortalidade. Para a avaliação da necessidade de intervenções hemodinâmicas e/ou revascularização miocárdica, há a necessidade da realização do cateterismo (CATE), procedimento de imagem indicado para evidenciar pontos de obstrução e determinar a melhor estratégia cirúrgica. Para a realização do CATE utiliza-se heparina sódica (5000 UI) in bolus. Atualmente, sabe-se que a heparina interfere no remodelamento de partículas lipoproteicas por liberação da lipoproteína lipase (LPL) e da lipase hepática (LH), essa ação pode alterar o transporte reverso do colesterol (TRC), em função de modificações no metabolismo das lipoproteínas. Métodos: foram selecionados por conveniência 20 pacientes, 10 do sexo masculino e 10 do sexo feminino, ambos os sexos, entre 45 e 73 anos, admitidos no Hospital Ana Neri, submetidos à cineangiocoronariografia (CATE). Todas as determinações laboratoriais foram realizadas antes e depois do CATE. Resultados: houve aumento significativo da atividade da lipase e diminuição da concentração dos triglicérides depois do CATE na análise geral e estratificada pelo sexo (p<0,05; Teste t pareado). A razão HDL-C/apoA aumentou significativamente depois do CATE, já a razão LDL-C/apoB não aumentou, nem diminuiu nas análises geral e estratificada por sexo. Enquanto a razão de risco cardiovascular TG/HDL-C diminuiu significativamente, a ApoB/apoA aumentou significativamente na análise geral e estratificada por sexo depois do CATE. As análises de correlações tiveram comportamentos diferentes, sendo a significância estatística encontrada dependente do grupo analisado (geral, masculino e feminino). A concentração do não-HDL-C, semelhante à determinação da haptoglobina, tiveram diminuição significativa na análise geral e no sexo masculino depois do CATE (p<0,05; Teste t pareado), o grupo feminino não mostrou significância. As taxas de incorporação de colesterol livre e fosfolípides não foram significativas depois do CATE. Conclusão: A administração in bolus de heparina sódica interfere no remodelamento de partículas lipoproteicas, sendo este fato evidenciado pelas variações das razões de risco, tais como, HDL-C/apoA, TG/HDL-C. O percentual de incorporação dos fosfolípides e colesterol livre na HDL mostrou-se influenciado em relação ao sexo, o que o torna relevante dado aos resultados encontrados. A utilização de razões de risco e ainda suas correlações mostraram-se melhores indicadores de desfecho sugestivo de doença cardiovascular nessa casuística do que quando avaliados apenas os marcadores séricos do perfil lipídico isoladamente. / Introduction: cardiovascular diseases affect thousands of people worldwide. Of these, the atherosclerotic disease is one of the most morbidity and mortality. To evaluate the need for hemodynamic interventions and / or CABG, the catheterization (CATE) is performed, an imaging procedure to evidence obstruction and to determine the best surgical strategy. To perform CATE, is necessary to use in bolus sodium heparin (5000 IU). Currently, it is known that heparin interferes with the remodeling of the lipoprotein particles by releasing lipoprotein lipase (LPL) and hepatic lipase (HL), this action may alter the reverse cholesterol transport (TRC), by changes in lipoprotein metabolism. Methods: were selected by convenience 20 patients, 10 male and 10 female, both gender, between 45 and 73 years old, admitted to the Hospital Ana Neri, who underwent coronary angiography (CATE). All laboratory measurements were performed before and after CATE. Results: were significant increase in lipase activity and decreased concentration of triglycerides after CATE, in the overall analysis and stratified by sex (p<0.05, paired t test). The HDL-C/apoA ratio increased significantly after CATE, since the LDL-C/apoB ratio has not increased or decreased in the general analysis, and stratified by gender. While TG/HDL-C cardiovascular risk ratio decreased significantly, ApoB/apoA increased significantly in the overall analysis, and stratified by sex after CATE. The correlation analysis had different behaviors, and the statistic significance found, were dependent of the group analyzed (generally male and female). The concentration of non-HDL-C, similar to the determination of haptoglobin, had a significant decrease in the overall analysis and in males after CATE (p<0.05, paired t-test), the female group do not show significance. The free cholesterol and phospholipids incorporation rates were not significant after the CATE. Conclusion: The administration of in bolus sodium heparin interferes in lipoprotein particles remodeling, by evidences from risk ratios variations, such as HDL-C/apoA, and TG/HDL-C. The percentage of phospholipids and free cholesterol incorporation in HDL shows sex influences, which makes it relevant to the obtained results. The use of hazard ratios and their correlations were better surrogate markers at these casuistic of cardiovascular disease than when serum markers of lipid profile were evaluated alone.

Lecithin:cholesterol acyltransferase (LCAT) was purified 30,000-fold from hog plasma in a homogeneous state as indicated by polyacrylamide gel electrophoresis. The purified enzyme had an apparent molecular weight of 66,000 and was found to contain about 21.4 percent (w/w) carbohydrate. The properties of hog LCAT including amino acid composition were compared with human LCAT. High density lipoprotein (HDL) was isolated from the hog plasma by an immunoaffinity column chromatography. The isolated HDL showed nearly identical lipid-protein composition although it contained additional protein components when it was compared to HDL isolated by a traditional method involving ultracentrifugation.

The physiological role of LCAT has been the subject of a number of recent articles (Glomset, 1979; Nilsson-Ehle et al., 1980). According to most current theories, the enzyme functions in combination with high-density lipoproteins in the reverse cholesterol transport pathway which presumably returns peripheral cholesterol to the liver where cholesterol catabolism takes place. Despite the exciting potential for studies on the catalytic function and the nature of the enzyme-substrate complex, the mechanism of action of LCAT remains largely unexplored. The relatively slow progress in the elucidation of the LCAT reaction mechanism is likely to be due to the difficulties in the isolation of the enzyme in sufficient quantities. Consequently, considerably less is known about the physical and chemical properties of the enzyme. Therefore, the first objective of this investigation was to isolate and purify sufficient amount of enzyme for subsequent characterization studies. The second objective of this investigation was to characterize the physical properties of the enzyme by techniques including analytical ultracentrifugation, ultraviolet spectroscopy, and circular dichroism and fluorescence spectroscopy. The third objective of this investigation was to characterize the chemical properties of the enzyme which deals with the amino acid and carbohydrate composition and with some basic structural features that are related to the chemical composition of LCAT.