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

The expression of two phenotypically-contrasting LDL receptor mutations was characterized in cultured fibroblasts from the genetically-homozygous Afrikaner subjects, FH1a and lb, and FH3a and 3b, respectively. Surface receptor expression and functional activity were studied by ligand (¹²⁵I-LDL) and monoclonal antibody (¹²⁵I-IgG-C7) binding, and c35s]-methionine pulse-chase experiments were used to analyze biosynthesis, processing and degradation of IgG-C7- immunoprecipitable mutant receptors. Cells from the "receptor-negative" subjects, FH3a and 3b exhibited reduced, but significant (40-60% of normal) LDL receptor synthesis rates. Newly-synthesized precursors were processed slowly (t½ 1.5 hours versus normal t½ of approximately 15 minutes) to mature receptors which reached the cell-surface, but were rapidly degraded thereafter with a half-life of approximately 1.7 hours (normal value 12.6 hours) thus representing a new type of LDL receptor defect. Lysosomotropic weak bases such as ammonium chloride partially inhibited rapid degradation of the mutant receptors, suggesting the involvement of proteolysis in acidic compartments such as lysosomes or endosomes. Fibroblasts from FH1a and lb exhibited normal synthesis rates of LDL receptor precursors that were processed at a severely reduced rate (t½ approximately 5 hours) to functionally heterogeneous mature surface receptors. Onethird of the receptors (20% of normal levels) bound ¹²⁵I-LDL with normal affinity at 4°C and 37°C, whereas the majority were able to recognize only ¹²⁵I-IgG-C7, and apparently showed defective internalisation and subsequent degradation of the bound IgG-C7 at 37°C. The existence of the two receptor populations was further supported by selective intracellular trapping and degradation of only the active, LDL-binding population, in the presence of ammonium chloride and LOL. The abnormal form predominated even in newly-synthesized receptors and reached a maximum of 50-70% of normal levels after 48 hours of upregulation. Upregulation kinetics and degradation rates (t½ = 10-11 hours) of both functionally-active and abnormal receptor populations were similar to normal. A progressive increase in apparent molecular weight of the slowly-processed precursor receptors suggested a possible role for abnormal glycosylation in the formation of both "normal" and abnormal conformations of the same receptor molecule.

Thèse (Med.Exp.) -- Université du Québec à Chicoutimi, programme en extension de l'Université Laval, 2006. / La p. de t. porte en outre: Mémoire présenté à la faculté des études supérieures de l'Université Laval comme exigence partielle du programme de maîtrise en médecine expérimentale - génétique des populations humaines offert à l'Université du Québec à Chicoutimi en vertu d'un protocole d'entente avec l'Université Laval pour l'obtention du grade de maître ès sciences (M.Sc.). CaQCU Bibliogr.: f. 63-101. Document électronique également accessible en format PDF. CaQCU

LDL-receptor mutations and familial defective apolipoprotein B-100 (codon 3500) (FOB), the known causes of monogenic hypercholesterolemia (MH), have similar clinical features. The nature of the mutations responsible for MH in South Africans of Indian origin was previously unknown. Similarly, the mutations in the LDL-receptor gene of a South African Black FH homozygote had also not been characterised. The aim of this thesis was to identify and analyse the LDL-receptor mutations in the Indian homozygotes NS, D, AV and AA and in the Black homozygote JL. In addition, the possible importance of FOB as a cause of MH in South Africans was also assessed. The patient NS was characterized as having two "Null" LDL-receptor alleles. His skin fibroblasts expressed no detectable LDL-receptor protein and very low levels of LDL-receptor mRNA of approximately normal size. Since NS' s LDLreceptor promoter sequence was normal, his alleles are likely to harbour exonic point mutations or minor rearrangements that cause premature stop codons. The patient D was found to be a heteroallelic homozygote. Two new point mutations in the LDL receptor, Asp₆₉ -Tyr and Glu₁₁₉-Lys, were identified. D's fibroblasts expressed about 30% of the normal surf ace complement of receptors that bound LDL poorly. This low number could at least be partially explained by their decreased stability. These mutations were not identified in any other Indian FH or hypercholesterolemic patients. Patients AV and AA were both shown to be homoallelic homozygotes for the Pro₆₆₄ -Leu mutation. This mutation was identified in 4 unrelated Muslim families of Gujerati origin suggesting that the mutation arose from this area in India. Contrary to previous reports (Knight et al. 1990, Soutar et al. 1989), neither LOL nor β-VLDL binding were shown to be affected by this mutation. These mutant receptors were rapidly degraded. Thus the disease FH in these subjects is presumably due to the low steady-state level of mature receptors that are functionally normal but exhibit accelerated turnover. The Pedi FH homozygote, JL, expressed very few LOL receptors due to decreased receptor synthesis associated with low mRNA levels and not due to enhanced degradation. One of JL's LOL receptor alleles has a 3 b.p. deletion in repeat 1 of the promoter (G. Zuilani, H. Hobbs and L.F. de Waal, personal communication). The nature of the defect in his other allele is unknown. The importance of FOB as a cause of monogenic hypercholesterolemia in the South African Indian, "Coloured" and Afrikaner populations was determined by screening hypercholesterolemic subjects with or without xanthomata. The absence of FOB in such patients, in whom the relevant common or founder South African mutations were excluded, suggested that this disorder was rarer in these groups than in North America and Europe. FOB was identified in two different families of mixed British and Afrikaner ancestry. One family contained individuals who were heterozygous for the FOB mutation, as well as the FH Afrikaner-1 and the FH Afrikaner-2 LOL-receptor mutations. In addition, 4 compound heterozygotes, who had both FOB and the FH Afrikaner-1 mutation and one individual whu inherited all 3 defects, were identified. This family allowed us to characterise the compound heterozygotes with one mutant LOLreceptor allele and FOB as having a condition that was probably intermediate in severity between the FH heterozygote and homozygote states.

Diss. (sammanfattning) Linköping : Univ., 2003. / Härtill 4 uppsatser.

A hipercolesterolemia familiar (HF) é caracterizada por concentrações elevadas de LDL-c e alta prevalência de doença arterial coronária (DAC) precoce. Entretanto, o curso da DAC nos portadores de HF é variável e pode ser influenciado por outros fatores de risco. O objetivo foi avaliar parâmetros clínicos e nutricionais de adultos portadores de HF heterozigótica por estudo do tipo transversal. Coletou-se do prontuário dos pacientes resultados de exames laboratoriais, medidas de pressão arterial e diagnósticos clínicos. Verificou-se a concordância ou não entre as categorias de risco pelos escores de Framingham (ERF) e pelos critérios estabelecidos para os portadores de HF. Antecedentes pessoais e familiares para DAC, tabagismo, atividade física, consumo alimentar de gorduras, fibras e bebidas alcoólicas foram obtidos por questionário e medidas antropométricas foram aferidas. Foram comparados os grupos com e sem Síndrome Metabólica (SM) e os grupos com e sem DAC por análise univariada. Após, foram verificados os fatores determinantes para o desenvolvimento da DAC mediante modelo de regressão multivariada. Foram entrevistados 110 pacientes (68 mulheres) com média de idade de 48,9 ± 16,2 anos. A presença de história familiar de DAC precoce foi relatada por 67 (61,5%) pacientes. A hipertensão foi encontrada em 59 (53,6%), SM em 38 (34,9%), DAC em 30 (27,3%), HDL-c baixo em 28 (25,5%), diabete melito em 17 (15,5%), 25 (22,7%) eram ex-fumantes e 12 (10,9%) tabagistas. Com a comparação das categorias de risco observou-se discrepância em 77,5% dos casos entre os ERF e os critérios estabelecidos para a população de HF. Quanto ao estado nutricional, 47 (42,7%) eram pré-obesos e 61 (55,4%) com circunferência da cintura alterada. O consumo de gorduras, fibras e bebidas alcoólicas foi considerado adequado. Encontrou-se grande número de sedentários (77%). O grupo dos pacientes com SM tinha idade mais avançada (55 vs 46 anos; p = 0,002), maior número de mulheres (76,3%; p = 0,02) e portadores de DAC (42,1%; p = 0,013). O grupo dos coronarianos tinha idade mais avançada (55 vs 47 anos; p = 0,004), mais pacientes do sexo masculino (60%; p = 0,004), maior presença de hipertensos (90%; p = 0,001), exfumantes (40%; p = 0,008), com SM (53,3%; p = 0,013), HDL-c baixo (53,3%; p = 0,001) e antecedente de infarto agudo do miocárdio (IAM) em irmãos (50%; p = 0,012). As medidas antropométricas, o consumo alimentar e a atividade física não foram diferentes entre os grupos. Após análise de regressão multivariada os fatores de risco determinantes para o desenvolvimento da DAC foram HDL-c baixo (OR 8,4; IC 95% 2,7-27,6), sexo masculino (OR 7,3; IC 95% 2,1-24,7), história de IAM em irmãos (OR 3,4; IC 95% 1,1-10,5) e idade avançada (OR 1,06; IC 95% 1,02-1,1). Em nossa população, HDL-c baixo, sexo masculino, história de IAM em irmãos e idade foram fatores independentes para o desenvolvimento da DAC. / Familial hypercholesterolaemia (FH) is characterized by raised concentrations of LDL-c and high prevalence of premature coronary artery disease (CAD). However, the course of the CAD in the FH is variable and can be influenced by other risk factors. The aim of the study was to assess clinical and nutritional parameters in adults with heterozigous FH by a cross sectional study. Laboratory exams, blood pressure measurement and clinical diagnosis were collected. Agreement or not between the categories of risk by Framingham scores and for established criteria for the FH subjects was verified. Personal and familial history for CAD, smoken habit, physical activity, fats, fibers and alcohol consumption were assessed by questionnaire and anthropometric measurement were verified. The groups with and without Metabolic Syndrome (MS) and groups with and without CAD were compared by univariated analysis. After, multivaried analysis (MVA) was used to assess the significance of differences in risk factors. The sample was composed by 110 patients (68 women) with average of age of 48.9 ± 16.2 years. The presence of familial history of premature CAD was detected in 67 (61.5%)subjects. Hypertension was found in 59 (53.6%), MS in 38 (34.9%), CAD in 30 (27.3%), low HDL-c in 28 (25.5%), diabetes in 17 (15.5%), 25 (22,7%) and 12 (10,9%) were respectively former and current smokers. In the comparison of the risk categories discrepancy was observed in 77.5% of the cases between the Framingham scores and the established criteria for the FH population. Analyzing the nutritional profile, 47 (42.7%) were overweight and 61 (55.4%) had increased waist circumference. The consumption of fats, fibers and alcohol were considered satisfactory. A great number of sedentary subjects was found (77%). The patients with MS were older (55 vs. 46 years; p = 0.002), had a greater number of women (76.3%; p = 0.02) and CAD (42.1%; p = 0.013). CAD subjects were older (55 vs. 47 years; p = 0.004), had a higher prevalence of males (60%; p = 0.004), hypertension (90%; p = 0.001), former smokers(40%; p = 0.008), MS (53.3%; p = 0.013), low HDL-c (53.3%; p = 0.001) and history of myocardial infarction in brothers (50%; p = 0.012). There were no differences between the groups regarding anthropometric measurements, consumption of fats, fiber and alcohol and physical activity. After MVA, independent risk factors for CAD were low HDL-c (OR 8.4; CI 95% 2.7-27.6), male gender (OR 7.3; CI 95% 2.1-24.7), history of myocardial infarction in brothers (OR 3.4; CI 95% 1.1-10.5) and advanced age (OR 1.06; CI 95% 1.02-1.1). In our population, low HDL-c, male gender, history of myocardial infarction in brothers and age were independently associated with the risk of CAD.

A hipercolesterolemia familiar (HF) é caracterizada por concentrações elevadas de LDL-c e alta prevalência de doença arterial coronária (DAC) precoce. Entretanto, o curso da DAC nos portadores de HF é variável e pode ser influenciado por outros fatores de risco. O objetivo foi avaliar parâmetros clínicos e nutricionais de adultos portadores de HF heterozigótica por estudo do tipo transversal. Coletou-se do prontuário dos pacientes resultados de exames laboratoriais, medidas de pressão arterial e diagnósticos clínicos. Verificou-se a concordância ou não entre as categorias de risco pelos escores de Framingham (ERF) e pelos critérios estabelecidos para os portadores de HF. Antecedentes pessoais e familiares para DAC, tabagismo, atividade física, consumo alimentar de gorduras, fibras e bebidas alcoólicas foram obtidos por questionário e medidas antropométricas foram aferidas. Foram comparados os grupos com e sem Síndrome Metabólica (SM) e os grupos com e sem DAC por análise univariada. Após, foram verificados os fatores determinantes para o desenvolvimento da DAC mediante modelo de regressão multivariada. Foram entrevistados 110 pacientes (68 mulheres) com média de idade de 48,9 ± 16,2 anos. A presença de história familiar de DAC precoce foi relatada por 67 (61,5%) pacientes. A hipertensão foi encontrada em 59 (53,6%), SM em 38 (34,9%), DAC em 30 (27,3%), HDL-c baixo em 28 (25,5%), diabete melito em 17 (15,5%), 25 (22,7%) eram ex-fumantes e 12 (10,9%) tabagistas. Com a comparação das categorias de risco observou-se discrepância em 77,5% dos casos entre os ERF e os critérios estabelecidos para a população de HF. Quanto ao estado nutricional, 47 (42,7%) eram pré-obesos e 61 (55,4%) com circunferência da cintura alterada. O consumo de gorduras, fibras e bebidas alcoólicas foi considerado adequado. Encontrou-se grande número de sedentários (77%). O grupo dos pacientes com SM tinha idade mais avançada (55 vs 46 anos; p = 0,002), maior número de mulheres (76,3%; p = 0,02) e portadores de DAC (42,1%; p = 0,013). O grupo dos coronarianos tinha idade mais avançada (55 vs 47 anos; p = 0,004), mais pacientes do sexo masculino (60%; p = 0,004), maior presença de hipertensos (90%; p = 0,001), exfumantes (40%; p = 0,008), com SM (53,3%; p = 0,013), HDL-c baixo (53,3%; p = 0,001) e antecedente de infarto agudo do miocárdio (IAM) em irmãos (50%; p = 0,012). As medidas antropométricas, o consumo alimentar e a atividade física não foram diferentes entre os grupos. Após análise de regressão multivariada os fatores de risco determinantes para o desenvolvimento da DAC foram HDL-c baixo (OR 8,4; IC 95% 2,7-27,6), sexo masculino (OR 7,3; IC 95% 2,1-24,7), história de IAM em irmãos (OR 3,4; IC 95% 1,1-10,5) e idade avançada (OR 1,06; IC 95% 1,02-1,1). Em nossa população, HDL-c baixo, sexo masculino, história de IAM em irmãos e idade foram fatores independentes para o desenvolvimento da DAC. / Familial hypercholesterolaemia (FH) is characterized by raised concentrations of LDL-c and high prevalence of premature coronary artery disease (CAD). However, the course of the CAD in the FH is variable and can be influenced by other risk factors. The aim of the study was to assess clinical and nutritional parameters in adults with heterozigous FH by a cross sectional study. Laboratory exams, blood pressure measurement and clinical diagnosis were collected. Agreement or not between the categories of risk by Framingham scores and for established criteria for the FH subjects was verified. Personal and familial history for CAD, smoken habit, physical activity, fats, fibers and alcohol consumption were assessed by questionnaire and anthropometric measurement were verified. The groups with and without Metabolic Syndrome (MS) and groups with and without CAD were compared by univariated analysis. After, multivaried analysis (MVA) was used to assess the significance of differences in risk factors. The sample was composed by 110 patients (68 women) with average of age of 48.9 ± 16.2 years. The presence of familial history of premature CAD was detected in 67 (61.5%)subjects. Hypertension was found in 59 (53.6%), MS in 38 (34.9%), CAD in 30 (27.3%), low HDL-c in 28 (25.5%), diabetes in 17 (15.5%), 25 (22,7%) and 12 (10,9%) were respectively former and current smokers. In the comparison of the risk categories discrepancy was observed in 77.5% of the cases between the Framingham scores and the established criteria for the FH population. Analyzing the nutritional profile, 47 (42.7%) were overweight and 61 (55.4%) had increased waist circumference. The consumption of fats, fibers and alcohol were considered satisfactory. A great number of sedentary subjects was found (77%). The patients with MS were older (55 vs. 46 years; p = 0.002), had a greater number of women (76.3%; p = 0.02) and CAD (42.1%; p = 0.013). CAD subjects were older (55 vs. 47 years; p = 0.004), had a higher prevalence of males (60%; p = 0.004), hypertension (90%; p = 0.001), former smokers(40%; p = 0.008), MS (53.3%; p = 0.013), low HDL-c (53.3%; p = 0.001) and history of myocardial infarction in brothers (50%; p = 0.012). There were no differences between the groups regarding anthropometric measurements, consumption of fats, fiber and alcohol and physical activity. After MVA, independent risk factors for CAD were low HDL-c (OR 8.4; CI 95% 2.7-27.6), male gender (OR 7.3; CI 95% 2.1-24.7), history of myocardial infarction in brothers (OR 3.4; CI 95% 1.1-10.5) and advanced age (OR 1.06; CI 95% 1.02-1.1). In our population, low HDL-c, male gender, history of myocardial infarction in brothers and age were independently associated with the risk of CAD.