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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Assessment of new iron chelating agents for treatment of iron-overload

Sarmento, Carlos V., 1980- January 2007 (has links)
Patients with acquired iron overload require chelation therapy using either Desferal or Exjade. Iron in excess may promote free radical formation in the Fenton reaction resulting in severe injuries of heart, liver and endocrine organs. Che1ators that bind ferric iron (Fe+3) in a 1:1 complex (Desferal) sequester it more efficiently than those che1ators that form 2:1 (Exjade) complexes. We initiated synthesis of new chelators derived from the tridentate chelator pyridoxal isonicotinoyl hydrazone (PIH) and its analogs. The aim of the synthesis was to generate chelators that bind iron in a 1:1 complex, which was confirmed for 8LK02, 10LK02, 11LK02 and 15LK03 by spectrophotometry. All novel chelators mobilized iron more efficiently compared to Desferal and Exjade from murine reticulocytes and human myeloid leukemia cells (K562). Additionally, aforementioned four chelators were also more efficient than PIH and were found to be less or equally toxic as Desferal and Exjade.
12

X-ray fluorescence measurements of skin iron using an I-125-based system

Tang, Bobby January 2023 (has links)
Iron overload conditions are a prevalent issue in global healthcare that require the accurate monitoring of iron levels to effectively provide treatment. X-ray fluorescence has emerged as a candidate for a point-of-care measurement tool for the detection of trace elements in vivo. This study explores the feasibility of a portable in vivo x-ray fluorescence (IVXRF) instrument using 125I as a point-of-care device in measuring skin iron levels. The system was calibrated using iron-doped water phantoms for various physiologically-applicable iron concentrations. Measurements were conducted on ex vivo rat skin samples (n = 34), which were then compared to a benchmark laboratory-based XRF system. Monte Carlo modelling using MCNP 6.2 was used to simulate the system in different conditions and provide an estimate of the radiation dose of the system on soft tissue. The R2 value for the calibration line of iron concentration in ppm to normalized iron signal was determined to be 0.985 (p < 0.01). For a measurement period of 1800 s real-time, the minimum detectable limit (MDL) of the system is 3.86 ± 0.06 ppm of iron. The R2 value for the linear regression between the IVXRF and benchmark XRF system normalized iron signals was 0.731 (p < 0.01). The R2 value for the linear regression between the IVXRF normalized iron signal and sample injected iron dose was 0.719 (p < 0.01), meaning the system can distinguish between different iron levels in rat skin. From the Monte Carlo simulations, the expected effective dose contribution from the IVXRF system is 101.68 ± 0.03 nSv. The IVXRF system was shown to accurately measure iron concentrations in ex vivo rat skin samples within the iron concentration ranges found within healthy and iron-overloaded patients. Further work shall be conducted to validate the system in in vivo applications. / Thesis / Master of Science (MSc) / Iron overload is a prevalent issue in healthcare, with many individuals experiencing detrimental symptoms, such as organ damage and heart failure. Modern treatment significantly improves quality of life but must be continuously monitored. This thesis covers the development of a non-invasive, cost-effective, and accurate system that can measure skin iron levels in patients to ensure effective monitoring. The results from this thesis suggest that the system can be used for clinical use to measure patient skin iron levels. It can theoretically measure iron in patients with normal and elevated iron levels. Simulation work suggests that the system will lead to negligible risk from radiation exposure. While this thesis and its findings support the feasibility of the system, further work is required before clinical implementation of the device.
13

Assessment of new iron chelating agents for treatment of iron-overload

Sarmento, Carlos V., 1980- January 2007 (has links)
No description available.
14

Cellular Iron Homeostasis Mechanisms in Erythrocytes and Colon Cells

Teria, Rodney Santos, Jr. January 2021 (has links)
No description available.
15

Caracterização sociodemográfica e clínica de pacientes com talassemia maior e diabetes mellitus de um centro de referência no interior de São Paulo / Sociodemographic and clinical characterization of patients with thalassemia major and diabetes mellitus of a reference center in São Paulo countryside

Olivatto, Gabriela Marsola 04 August 2017 (has links)
A maior expectativa de vida dos pacientes com talassemia maior, as repetidas transfusões de concentrado de hemácias como parte do tratamento, podem ocasionar maior deposição de ferro nos órgãos, e consequentemente, as comorbidades. Dessa forma, dentre as comorbidades endócrinas, temos o diabetes mellitus como uma das principais, sendo necessário conhecer o panorama em nossa realidade. O estudo tem como objetivos determinar a prevalência do diagnóstico de diabetes em pacientes com talassemia maior, caracterizar e comparar os pacientes com talassemia maior, e diabetes mellitus, segundo as variáveis sociodemográficas e clínicas.Trata-se de um estudo descritivo e transversal, realizado em um centro de referência no tratamento de talassemia do interior paulista. A amostra foi constituída por 31 pacientes com talassemia maior. Para a coleta de dados utilizou-se um instrumento subdividido em duas partes. Os dados sociodemográficos e clínicos foram obtidos por meio de entrevista dirigida e os resultados de exames laboratoriais pelo prontuário eletrônico do paciente, no período de junho a agosto de 2015. Os dados foram digitados e importados para o programa SPSS for Windows, versão 17.0 e submetidos à análise estatística descritiva. O projeto foi aprovado pelo Comitê de Ética em Pesquisa da Escola de Enfermagem de Ribeirão Preto da Universidade de São Paulo (CEP/EERP-USP), sob Protocolo nº 41912415.3.0000.5393. Dos 31 pacientes com talassemia maior, 5 (16,1%) tinham diabetes mellitus. Em relação as variáveis sociodemográficas, não houve diferenças na distribuição dos pacientes entre os sexos, a maioria eram solteiros e cursaram até o ensino médio completo. A idade variou de cinco a 48 anos, com média de 24,9 anos de idade, a maioria recebia até 10 salários mínimos, eram estudantes e possuíam carteira de trabalho assinada. No que tange às variáveis clínicas, temos que o tratamento utilizado predominante foi o quelante oral deferasirox, e naqueles pacientes com diabetes, além do deferasirox, a maioria utilizava a insulina. O esquema transfusional predominante foi o de 15 a 22 dias. O índice de massa corpórea foi classificado como eutrófico e a pressão arterial, considerada ótima para a maioria dos pacientes. Quanto aos achados dos exames laboratoriais, os pacientes com diabetes e talassemia apresentaram valores alterados de glicemia de jejum e transaminase, já os pacientes sem diabetes apresentaram valores alterados de ferritina sérica. No que se refere aos achados dos exames de imagem, nenhum paciente com diabetes e Talassemia maior apresentou massa óssea adequada, o que reforça a importância de seu monitoramento. Destaca-se o aumento de sobrecarga cardíaca para os pacientes com diabetes e talassemia. Para os pacientes com talassemia e sem diabetes, a maioria apresentou grave sobrecarga de ferro hepático na ressonância magnética do fígado, enquanto para a maioria dos pacientes com diabetes foi considerado normal. Dessa forma, conhecer as características clínicas dos pacientes com talassemia maior e diabetes permite subsidiar a assistência de enfermagem qualificada e contribuir com a saúde dos pacientes com condições crônicas. Contudo, os nossos achados corroboram com as taxas de prevalência de diabetes em pacientes com talassemia maior encontradas na literatura nacional e internacional / The longer life expectancy of patients with thalassemia major, repeated red blood cell transfusions as part of the treatment, may lead to increased iron deposition in the organs, and consequently, comorbidities. Thus, among the endocrine comorbidities, we have diabetes mellitus as one of the main ones, being necessary to know the panorama in our reality. The aim of the study was to determine the prevalence of diabetes in patients with thalassemia major and to characterize and compare patients with thalassemia major, and diabetes mellitus, according to sociodemographic and clinical variables.This is a descriptive and cross-sectional study, carried out in a reference center in thalassemia treatment of São Paulo countryside. The sample consisted of 31 patients with thalassemia major. For data collection, an instrument was divided into two parts. Sociodemographic and clinical data were obtained by means of a directed interview and the laboratory tests results by the patient\'s electronic record, from June to August 2015. Data were loaded into SPSS for Windows software, version 17.0 and submitted to descriptive statistical analysis. The project was approved by the Research Ethics Committee of the University of São Paulo at Ribeirão Preto College of Nursing (CEP / EERP-USP) under Protocol No. 41912415.3.0000.5393. Of the 31 patients with thalassemia major, 5 (16,1%) had diabetes mellitus. Regarding the sociodemographic variables, there were no differences in the distribution of the patients between the sexes, most of them were single and enrolled in high school. The age ranged from five to 48 years, with a mean of 24,9 years of age, the majority received up to 10 minimum wages, were students and had a work contract. Regarding the clinical variables, we have that the predominant treatment was the oral chelator deferasirox, and in those patients with diabetes, in addition to deferasirox, the majority used insulin. The predominant transfusion regimen was 15 to 22 days. Body mass index was classified as eutrophic and blood pressure was considered optimal for most patients. Regarding the laboratory findings, patients with diabetes and thalassemia had altered values of fasting glycemia and transaminase, whereas patients without diabetes had altered values of serum ferritin. Regarding imaging exams findings, no patient with diabetes and major thalassemia presented adequate bone mass, which reinforces the importance of their monitoring. The increase in cardiac overload for patients with diabetes and thalassemia stands out. For patients with thalassemia and without diabetes, the majority had severe hepatic iron overload in the magnetic resonance imaging of the liver, while for most patients with diabetes it was considered normal. Thus, knowing the clinical characteristics of patients with thalassemia major and diabetes allows subsidizing qualified nursing care and contributing to the health of patients with chronic conditions. However, our findings corroborate the prevalence rates of diabetes in patients with thalassemia major found in the national and international literature
16

O papel das mutações do gene HFE  e da sobrecarga de ferro na evolução da hepatite crônica pelo VHC / The role of HFE gene mutations and iron overload in the history of chronic hepatitis C

Silva, Ana Lúcia Bernardes da 16 September 2009 (has links)
Introdução: A infecção pelo VHC é uma epidemia de proporções globais, que se torna crônica em cerca de 85% dos indivíduos. Sobrecarga de ferro secundária a mutações HFE vem sendo proposta como fator agravante na evolução da hepatite crônica C. Objetivos: Avaliar se sobrecarga de ferro, mutações no gene HFE estão associadas a progressão da fibrose hepática e a carcinoma hepatocelular (CHC) em portadores crônicos VHC. Casuística e Métodos: De um banco de 2300 pacientes matriculados nos Ambulatórios de Hepatologia e de Transplante Hepático do HCFMUSP, selecionaram-se 320 portadores de hepatite crônica C. Os homens (55,6%) apresentaram 50,8 anos de idade em média e as mulheres 54,3. Obtiveram-se dados clínicos e laboratoriais da época da biópsia hepática, admissionais ou com pelo menos um ano de wash-out do tratamento antiviral. Considerou-se sobrecarga bioquímica níveis de ferro, saturação da transferrina e ferritina acima dos valores de referência. Sobrecarga de ferro tecidual foi identificada pela coloração de Perls graus 3-4. As mutações HFE C282Y e H63D foram pesquisadas pela técnica de PCR em tempo real, em DNA extraído de sangue total, após assinatura de TCLE aprovado pelo comitê de ética local. A fibrose hepática foi considerada avançada para graus 3-4 da classificação SBH/SBP e Metavir (n=167, 52,2%). CHC foi definido por biópsia ou por imagem típica por 2 métodos e AFP 400 mg/dL (n=45, 14,1%). Investigaram-se antecedentes de etilismo, diabetes mellitus, IMC e esteatose em biópsia hepática. A partir dos resultados de genotipagem HFE, constituiu-se um subgrupo caso-controle (n=182) com os portadores de mutações e pares de idade, sexo, etnia e IMC similares. Procederam-se análises de correlação bivariada e multivariada (IC=95%) nos grupos geral e caso-controle. Resultados: Quando se compararam casos com fibrose leve vs avançada, observaram-se níveis elevados de ferro em 17,7% vs 25,2% (p=0,019); saturação da transferrina em 24,3% vs 36,7% (p=0,001); ferritina em 25,8% vs 32,4% (p=0,040) e sobrecarga de ferro tecidual em 3,6% vs 1,4% (p=0,126). Quanto à mutação C282Y, observaram-se frequências alélicas de 0,9% vs 2,0% (p=0,110) e à H63D 5,0% vs 8,0% (p=0,033). No subgrupo casocontrole, as associações de C282Y e H63D com fibrose avançada ocorreram com significâncias de p=0,072 e 0,008, respectivamente. A análise multivariada, tendo fibrose como variável dependente nesse mesmo subgrupo, confirmou as associações com C282Y (OR=31,45; p=0,006) e H63D (OR=33,70; p=0,001). Neste mesmo subgrupo, a presença de pelo menos um alelo mutante esteve associada à ocorrência de CHC (p=0,015). Não se identificaram outros parâmetros associados a transformação carcinomatosa. Na análise multivariada, foram variáveis associadas a evolução da fibrose idade avançada (OR=2,36; p=0,000), etilismo (OR=2,18; p=0,007), saturação da transferrina (OR=2,11; p=0,010) e mutação H63D (OR=1,97; p=0,03). Discussão e Conclusões: Houve correlação de graus mais avançados de fibrose com níveis elevados de ferro, saturação da transferrina e ferritina; contudo, esses marcadores também podem estar igualmente elevados nos indivíduos com pouca fibrose. Ao contrário, em muitos casos, a sobrecarga bioquímica de ferro pode ser conseqüência da progressão da doença hepática, e não sua causa. As mutações H63D e C282Y ocorreram em associação com maiores graus de alteração arquitetural; mas, como não houve associação entre siderose tecidual e fibrose, é possível que seu papel na agressão hepática não ocorra diretamente por meio da sobrecarga de ferro. Os portadores de mutações HFE apresentam CHC com maior frequência que seus casos-controle. / Introduction: HCV infection is an epidemic of global proportions, which becomes chronic in about 85% of individuals. Iron overload due to HFE mutations has been proposed as aggravating factor in the evolution of chronic hepatitis C. Objectives: To assess whether iron overload, mutations in the HFE gene are associated with progression of liver fibrosis and hepatocellular carcinoma (HCC) in chronic HCV. Patients and Methods: From a database of 2300 patients enrolled in the outpatient clinics of Hepatology and Liver Transplantation, HCFMUSP, 320 patients with chronic hepatitis C were selected. Men (55.6%) were 50.8 years old on average and women 54.3. Admissional clinical and laboratory data at the time of liver biopsy were obtained; when patient had been previously treated with antiviral drugs, the wash-out period required was of at least one year. Biochemical iron overload was defined as iron, ferritin and transferrin saturation above the reference values. Tissue iron overload was identified by Perls staining of grades 3-4. The HFE C282Y and H63D mutations were searched by real-time PCR technique in DNA extracted from whole blood, after signing of FICT approved by the local ethics committee. The liver fibrosis was considered advanced for grades 3-4 in the classification SBH/SBP and METAVIR(n = 167, 52.2%). HCC was defined by biopsy or by typical image by 2 methods and AFP 400 mg / dL (n = 45, 14.1%). Personal history of alcoholism, diabetes mellitus, BMI and steatosis in liver biopsy were obtained. A casecontrol group was constituted based on the results of HFE genotyping (n = 182), subjects were paired by age, gender, ethnicity and BMI. Bivariate correlation and multivariate analysis (CI = 95%) groups in general and case-control were carried-out. Results: When comparing patients with mild vs advanced fibrosis, biochemical high levels of iron were detected in 17.7% vs 25.2% (p = 0.019), transferrin saturation in 24.3% vs 36.7% (p = 0.001), ferritin in 25.8% vs 32.4% (p = 0.040) and tissue iron overload in 3.6% vs 1.4% (p = 0.126). Regarding to HFE mutations, the allelic frequencies of C282Y were 0.9% vs 2.0% (p = 0.110); and of H63D, 5.0% vs 8.0% (p = 0.033). In casecontrol group, associations of C282Y and H63D with advanced fibrosis occurred with significance of p=0.072 and 0.008, respectively. Multivariate analysis with fibrosis as the dependent variable in that group, confirmed the associations with C282Y (OR = 31.45, p = 0.006) and H63D (OR = 33.70, p = 0.001). In this same subgroup, the presence of at least one mutant allele was associated with occurrence of HCC (p = 0.015). There were not any other parameters found in association with carcinomatous transformation. The multivariate analysis using fibrosis as dependent variable showed association with age (OR = 2.36, p = 0.000), alcoholism (OR = 2.18, p = 0.007), transferrin saturation (OR = 2.11, p = 0.010) and H63D mutation (OR = 1.97, p = 0.03). Discussion and Conclusions: Advanced degrees of fibrosis were correlated with high levels of iron, transferrin saturation and ferritin; however, these markers can also be elevated in individuals with slight fibrosis. In contrary, in many cases, the biochemistry of iron overload may be a consequence of progression of liver disease. C282Y and H63D mutations occurred in association with more advanced fibrosis. However, as there was not any correlation between tissue siderosis and fibrosis, it might be possible that liver injury occurs not by the iron overload pathway. Finally, carriers of HFE mutations were found with HCC more frequently than their casecontrol.
17

Caracterização sociodemográfica e clínica de pacientes com talassemia maior e diabetes mellitus de um centro de referência no interior de São Paulo / Sociodemographic and clinical characterization of patients with thalassemia major and diabetes mellitus of a reference center in São Paulo countryside

Gabriela Marsola Olivatto 04 August 2017 (has links)
A maior expectativa de vida dos pacientes com talassemia maior, as repetidas transfusões de concentrado de hemácias como parte do tratamento, podem ocasionar maior deposição de ferro nos órgãos, e consequentemente, as comorbidades. Dessa forma, dentre as comorbidades endócrinas, temos o diabetes mellitus como uma das principais, sendo necessário conhecer o panorama em nossa realidade. O estudo tem como objetivos determinar a prevalência do diagnóstico de diabetes em pacientes com talassemia maior, caracterizar e comparar os pacientes com talassemia maior, e diabetes mellitus, segundo as variáveis sociodemográficas e clínicas.Trata-se de um estudo descritivo e transversal, realizado em um centro de referência no tratamento de talassemia do interior paulista. A amostra foi constituída por 31 pacientes com talassemia maior. Para a coleta de dados utilizou-se um instrumento subdividido em duas partes. Os dados sociodemográficos e clínicos foram obtidos por meio de entrevista dirigida e os resultados de exames laboratoriais pelo prontuário eletrônico do paciente, no período de junho a agosto de 2015. Os dados foram digitados e importados para o programa SPSS for Windows, versão 17.0 e submetidos à análise estatística descritiva. O projeto foi aprovado pelo Comitê de Ética em Pesquisa da Escola de Enfermagem de Ribeirão Preto da Universidade de São Paulo (CEP/EERP-USP), sob Protocolo nº 41912415.3.0000.5393. Dos 31 pacientes com talassemia maior, 5 (16,1%) tinham diabetes mellitus. Em relação as variáveis sociodemográficas, não houve diferenças na distribuição dos pacientes entre os sexos, a maioria eram solteiros e cursaram até o ensino médio completo. A idade variou de cinco a 48 anos, com média de 24,9 anos de idade, a maioria recebia até 10 salários mínimos, eram estudantes e possuíam carteira de trabalho assinada. No que tange às variáveis clínicas, temos que o tratamento utilizado predominante foi o quelante oral deferasirox, e naqueles pacientes com diabetes, além do deferasirox, a maioria utilizava a insulina. O esquema transfusional predominante foi o de 15 a 22 dias. O índice de massa corpórea foi classificado como eutrófico e a pressão arterial, considerada ótima para a maioria dos pacientes. Quanto aos achados dos exames laboratoriais, os pacientes com diabetes e talassemia apresentaram valores alterados de glicemia de jejum e transaminase, já os pacientes sem diabetes apresentaram valores alterados de ferritina sérica. No que se refere aos achados dos exames de imagem, nenhum paciente com diabetes e Talassemia maior apresentou massa óssea adequada, o que reforça a importância de seu monitoramento. Destaca-se o aumento de sobrecarga cardíaca para os pacientes com diabetes e talassemia. Para os pacientes com talassemia e sem diabetes, a maioria apresentou grave sobrecarga de ferro hepático na ressonância magnética do fígado, enquanto para a maioria dos pacientes com diabetes foi considerado normal. Dessa forma, conhecer as características clínicas dos pacientes com talassemia maior e diabetes permite subsidiar a assistência de enfermagem qualificada e contribuir com a saúde dos pacientes com condições crônicas. Contudo, os nossos achados corroboram com as taxas de prevalência de diabetes em pacientes com talassemia maior encontradas na literatura nacional e internacional / The longer life expectancy of patients with thalassemia major, repeated red blood cell transfusions as part of the treatment, may lead to increased iron deposition in the organs, and consequently, comorbidities. Thus, among the endocrine comorbidities, we have diabetes mellitus as one of the main ones, being necessary to know the panorama in our reality. The aim of the study was to determine the prevalence of diabetes in patients with thalassemia major and to characterize and compare patients with thalassemia major, and diabetes mellitus, according to sociodemographic and clinical variables.This is a descriptive and cross-sectional study, carried out in a reference center in thalassemia treatment of São Paulo countryside. The sample consisted of 31 patients with thalassemia major. For data collection, an instrument was divided into two parts. Sociodemographic and clinical data were obtained by means of a directed interview and the laboratory tests results by the patient\'s electronic record, from June to August 2015. Data were loaded into SPSS for Windows software, version 17.0 and submitted to descriptive statistical analysis. The project was approved by the Research Ethics Committee of the University of São Paulo at Ribeirão Preto College of Nursing (CEP / EERP-USP) under Protocol No. 41912415.3.0000.5393. Of the 31 patients with thalassemia major, 5 (16,1%) had diabetes mellitus. Regarding the sociodemographic variables, there were no differences in the distribution of the patients between the sexes, most of them were single and enrolled in high school. The age ranged from five to 48 years, with a mean of 24,9 years of age, the majority received up to 10 minimum wages, were students and had a work contract. Regarding the clinical variables, we have that the predominant treatment was the oral chelator deferasirox, and in those patients with diabetes, in addition to deferasirox, the majority used insulin. The predominant transfusion regimen was 15 to 22 days. Body mass index was classified as eutrophic and blood pressure was considered optimal for most patients. Regarding the laboratory findings, patients with diabetes and thalassemia had altered values of fasting glycemia and transaminase, whereas patients without diabetes had altered values of serum ferritin. Regarding imaging exams findings, no patient with diabetes and major thalassemia presented adequate bone mass, which reinforces the importance of their monitoring. The increase in cardiac overload for patients with diabetes and thalassemia stands out. For patients with thalassemia and without diabetes, the majority had severe hepatic iron overload in the magnetic resonance imaging of the liver, while for most patients with diabetes it was considered normal. Thus, knowing the clinical characteristics of patients with thalassemia major and diabetes allows subsidizing qualified nursing care and contributing to the health of patients with chronic conditions. However, our findings corroborate the prevalence rates of diabetes in patients with thalassemia major found in the national and international literature
18

DETERMINATION OF FERRITIN AND HEMOSIDERIN IRON IN PATIENTS WITH NORMAL IRON STORES AND IRON OVERLOAD BY SERUM FERRITIN KINETICS

NAOE, TOMOKI, HAYASHI, HISAO, MAEDA, HIDEAKI, OHASHI, HARUHIKO, TOMITA, AKIHIRO, SAITO, HIROSHI 02 1900 (has links)
No description available.
19

Measurement, modelling and potential clinical applications of spatial variations in magnetic resonance proton transverse relaxation rates in iron-loaded liver and heart tissue

Pontre, Beau January 2006 (has links)
[Truncated abstract. Formulae and special characters in this field can only be approximated. See PDF version for accurate reproduction.] Magnetic resonance imaging (MRI) has been developed over the past two and a half decades to enable non-invasive assessment of soft tissues in the human body. MRI provides images of the tissues in the body with intensities weighted by nuclear magnetic relaxation properties of the tissue. Recent advances have utilised MRI as a quantitative tool with the nuclear magnetic relaxation rates in tissues being accurately quantified. One clinical application of quantitative MRI has been in the quantification of body iron stores in the management of iron overload diseases. MR images also contain information about the spatial variations of relaxation rates, which could be clinically useful. In the quantification of liver iron concentrations, proton transverse relaxation rate (R2) maps have been used not only to quantify iron concentrations but also to visualise the spatial variations. The work in this thesis addresses the use of spatial information from proton transverse relaxation rate maps in clinical practice. The quantitative spatial information contained in these maps is analysed in two clinically important settings, namely the non-invasive assessment of liver fibrosis and the assessment of magnetic susceptibility artefacts in cardiac proton transverse relaxometry. Spatial distributions of liver R2 maps were quantified using texture measures based on grey-tone spatial dependence (GTSD) matrices. Some of these measures gave a statistically significant distinction between patients with minimal or no fibrosis and those with fibrosis or cirrhosis. Distinction of fibrosis using this technique was enhanced in subjects with iron overload diseases, suggesting that iron is required as a contrast agent for sufficient sensitivity of image texture to fibrosis. In subjects with low tissue iron concentrations, tissue hydration was observed to also have an influence on R2. In patients with end stage liver disease, a model combining tissue iron concentration and tissue hydration gave a better prediction of R2 than iron concentration alone. A model combining several of the texture measures was developed using logistic regression and was found to improve distinction of high-grade fibrosis from low-grade fibrosis. For the distinction of F0 and F1 fibrosis stages (as assessed by the METAVIR system) from F2 and above the area under the receiver-operating characteristic (ROC) curve was 0.75. As this model was developed using a cohort of subjects with varying pathologies, the performance of the model is expected to improve if only iron-loaded subjects are considered.
20

Mutation analysis of four genes implicated in iron homeostasis in porphyria cutanea tarda (PCT) patients

Panton, Nicola 03 1900 (has links)
Thesis (MSc (Genetics))--University of Stellenbosch, 2008. / The porphyrias are a group of genetic diseases resulting from the accumulation of haem precursors due to defective enzyme activity in either one of the last seven enzymes in the haem biosynthesis pathway. One of the common hepatic porphyrias, porphyria cutanea tarda (PCT), arises from the inhibition of uroporphyrinogen decarboxylase (UROD) activity. It is characterised by excessive urinary and hepatic excretion of uroporphyrinogens and manifests cutaneously in the form of dermatitis. Two main forms of PCT have been described, namely familial PCT (fPCT) and sporadic PCT (sPCT). PCT is a complex disease and a few genetic (including modifier loci) and environmental precipitating factors have been implicated in the aetiology of PCT. An important exacerbating factor, iron overload, is observed in the majority of PCT patients. The aim of this study was to determine whether DNA sequence variation in the 5' untranslated regulatory region of four genes involved in iron metabolism i.e. CP, CYBRD1, HAMP and SLC40A1 may in any way be associated with PCT. The study cohort consisted of 74 patients from three diverse South African populations including 15 Black (eight males and seven females), 30 Caucasian (13 male and 17 females) and 29 Coloured (18 males and 11 females) individuals as well as 132 population-matched controls. The promoter region of the selected genes were screened for variation utilising the techniques of polymerase chain reaction (PCR) amplification, heteroduplex single-stranded conformational polymorphism (HEX-SCCP) analysis, restriction fragment length polymorphism (RFLP) analysis and bi-directional semi-automated DNA sequencing. Twenty three previously described and eleven novel variants were identified. The novel variants comprised CYBRD1: -1540G/A, -1474G/A, -1452T/C, -1346T/C, -1272T/C, -645T/C; G(T)8G(T)nG(T)nG(T)9; HAMP: -429G/T and SLC40A1: -1461T/C, -1399G/A, -524C/T. Statistically significant associations were observed at a number of loci. In silico analysis revealed several putative transcription factor binding sites (TFBSs) spanning the regions of variation. The disruption of an existing (or creation of a novel) TFBS is thought to occur in the presence of a variant in a number of instances. This may lead to the manipulation of transcription rates, thereby depicting a possible mechanism for gene dysregulation. The study presented here was undertaken as a preliminary investigation to determine the contribution (if any) of variants in the regulatory regions of candidate genes in iron metabolism in South African PCT patients. Considering the increasing incidence of PCT, in particular the Black South African population, it is necessary to elucidate the underlying mechanisms of iron overload in PCT patients. The propitious findings signified in the study, in conjunction with phenotypegenotype correlations, will assist in clarifying the association between iron overload and PCT. / jfl2010 / Imported from http://etd.sun.ac.za April 2010.

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