Four strains of the swine pathogen Actinobacillus pleuropneumoniae, namely, the type strain (ATCC 27088), the "reference" strain of biotype 2 (Bertschinger 2008/76) and two additional biotype 1 strains, strain BC181, which is less virulent than the type strain, and strain K17 (reference strain of serotype 5A), which was isolated from a lamb, were investigated with respect to iron acquisition. All four strains produced iron-repressible outer membrane proteins. However, only strains ATCC 27088 and Bertschinger 2008/76 could acquire iron from porcine transferrin. No organism could utilize human, bovine or ovine transferrin, or ovine or porcine lactoferrin. Haemoglobin supported good growth of all strains except K17 (which also failed to acquire iron from haemin). In all cases, iron acquisition from transferrin or haemoglobin required direct contact between the organisms and the proteins. Total membranes derived from iron-restricted organisms were subjected to an affinity isolation technique based on biotinylated porcine transferrin and streptavidin-agarose, and the following polypeptides were isolated: 99 kDa and 64 kDa from strain ATCC 27088; 93 kDa from strain Bertschinger 2008/76; 95 kDa (trace amounts) and 60 kDa from strain BC181; none from strain K17. These polypeptides appear to be transferrin receptor components. The 99 kDa polypeptide (TBPl) from the type strain was purified by SDS-PAGE and transferred electrophoretically onto polyvinylidene difluoride membrane. The N-terminal amino acid sequence of the polypeptide was determined commercially. A commercially-synthesized oligonucleotide probe was used to clone the gene encoding the TBPl of the type strain in competent Escherichia coli DH5$ alpha$ cells.

Presented for the degree of Doctor of Science of University of the Uiituatersrand. October, 1964. / ffiy interest in iron metabolism was initially aroused in 1948 by a young patient with idiopathic haemochromatosis who was admitted to Professor Elliott*© ward while I was serving my medical internship, With the support of the Council for Scientific and Industrial Research it was possible to carry out radioisotopic studies on this patient and over the next four years a number of other subjects with the same disease ware investigated. As the study continued, attention was also directed to the siderosis which is so common in adult Bantu, and to the Iron overload which results from the administration of repeated blood transfusions to subjects with refractory anaemias. / IT2018

A dissertation submitted to the Faculty of Medicine, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the Degree Master of Science in Medicine. Johannesburg, 1995 / HLA-linked haemochromatosis is the result of an inborn error of metabolism inherited as an autosomal recessive gene, closely linked to the HLA locus on chromosome six. In this condition iron absorption is inappropriately high leading to iron overload. Integral to the pathogenesis of this disorder and in contrast to other causes of iron overload, is the relatively modest accumulation of iron within cells of both the small intestine and the reticuloendothelial system and the excessive deposition of iron in parenchymal cells of the liver and other organs. This observation has led to the suggestion that the primary defect(s) could be present in either the gut, the liver, the reticuloendothelial system or all three. Abnormalities in iron uptake by cells, iron transport through and between cells and iron storage in cells have all been suggested as possible mechanisms responsible for the abnormal absorption and distribution of iron in haemochromatosis. Malfunction of the iron transport protein transferrin or its receptor could be responsible for abnormal distribution and iron loading while an abnormality of ferritin iron storage could explain why some cells appear to be unable to store iron and others are iron overloaded. / IT2018

No description available.

No description available.

Thesis (PhD)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: Iron is an essential micronutrient that is an absolute requirement for correct cellular function in all eukaryotic organisms. However, ferrous iron has the ability to catalyze the formation of potentially toxic reactive oxygen species and regulation of iron metabolism is therefore of critical importance. Currently, there is little known about the co-ordinated regulation of the plethora of genes coding for proteins involved in this biochemical pathway, with the exception of the well characterized post-transcriptional IRE/IRP system. Regulation of gene expression in eukaryotic organisms is a highly intricate process. Transcriptional regulation is the first step and is controlled by the presence of specific cis-regulatory regions (cis-motifs), residing within the promoter region of genes, and the functional interactions between the products of specific regulatory genes (transcription factors) and these cismotifs. A combinatorial bioinformatic and functional approach was designed and utilized in this study for the analysis of the promoter architecture of genes of the iron metabolic pathway. The upstream non-coding region (~2 kb) of 18 genes (ACO1, CP, CYBRD1, FTH1, FTL, HAMP, HEPH, HFE, HFE2, HMOX1, IREB2, LTF, SLC11A2, SLC40A1, STEAP3, TF, TFRC, TFR2), known to be involved in the iron metabolism pathway, was subjected to computational analyses to identify regions of conserved nucleotide identity utilizing specific software tools. A subset of nine (CYBRD1, FTH1, HAMP, HFE, HFE2, HMOX1, IREB2, LTF, TFRC) of the genes were found to contain a genomic region that demonstrated over 75% sequence identity between the genes of interest. This conserved region (CR) is approximately 140 bp in size and was identified in each of the promoters of the nine genes. The CR was subjected to further detailed examination with comparative algorithms from different software for motif detection. Four specific cis-motifs were discovered within the CR, which were found to be in the same genomic position and orientation in each of the CR-containing genes. In silico prediction of putative transcription factor binding sites revealed the presence of numerous binding motifs of interest that could credibly be associated with a biological function in this pathway, including a novel MTF-1 binding site in five of the genes of interest. Validation of the bioinformatic predictions was performed in order to fully assess the relevance of the results in an in vitro setting. Luciferase reporter constructs for the nine CRcontaining genes were designed containing: 1) the 2 kb promoter, 2) a 1.86 kb promoter with the CR removed and 3) the 140 bp CR element. The expression levels of these three reporter gene constructs were monitored with a dual-luciferase reporter assay under standard culture conditions and simulated iron overload conditions in two different mammalian cell lines. Results of the luciferase assays indicate that the CR promoter constructs displayed statistically significant variation in expression values when compared to the untreated control constructs. Further, the CR appears to mediate transcriptional regulatory effects via an iron-independent mechanism. It is therefore apparent that the bioinformatic predictions were shown to be functionally relevant in this study and warrant further investigation. Results of these experiments represent a unique and comprehensive overview of novel transcriptional control elements of the iron metabolic pathway. The findings of this study strengthen the hypothesis that genes with similar promoter architecture, and involved in a common pathway, may be co-regulated. In addition, the combinatorial strategy employed in this study has applications in alternate pathways, and could serve as a refined approach for the prediction and study of regulatory targets in non-coding genomic DNA. / AFRIKAANSE OPSOMMING: Yster is ‘n noodsaaklike mikrovoedingstof wat ‘n vereiste is vir korrekte sellulêre funksie in alle eukariotiese organismes. Yster (II) of Fe2+ het egter die vermoë om die vorming van potensiële toksies reaktiewe suurstof spesies te kataliseer en dus is die regulasie van die yster metaboliese padweg van kardinale belang. Tans is daar beperkte inligting oor koördineerde regulasie van die gene, en dus proteïene waarvoor dit kodeer, in hierdie padweg. ‘n Uitsondering is die goed gekarakteriseerde na-transkripsionele “IRE/IRP” sisteem. Regulasie van geenuitdrukking in eukariotiese organismes is ‘n ingewikkelde proses. Transkripsionele regulasie is die eerste stap en word beheer deur die teenwoordigheid van spesefieke cis-regulatoriese elemente (cis-motiewe), geleë in die promotor area van gene, en die funksionele interaksies wat plaasvind tussen die produkte van spesifieke regulatoriese faktore (of transkripsie faktore) en hierdie cis-motiewe. ‘n Gekombineerde bioinformatiese en funksionele benadering was ontwerp en daarna gebruik in dié studie vir die analise van die promotor argitektuur van gene wat ‘n rol speel in die yster metaboliese padweg. Die stroomop nie-koderende streek (~2 kb) van 18 gene (ACO1, CP, CYBRD1, FTH1, FTL, HAMP, HEPH, HFE, HFE2, HMOX1, IREB2, LTF, SCL11A2, SLC40A1, STEAP3, TF, TFRC, TFR2), bekend vir hul betrokkenheid in die yster metabolisme padweg, was bloodgestel aan bioinformatiese analises om die streke van konservering te identifiseer met die hulp van spesifieke sagteware. Slegs nege (CYBRD1, FTH1, HAMP, HFE, HFE2, HMOX1, IREB2, LTF, TFRC) van die geanaliseerde gene het ‘n genomiese area bevat wat meer as 75% konservering getoon het. Hierdie gekonserveerde area (GA) is 140 bp in lengte en is geïdentifiseer in elk van die promotors van die nege gene. Die GA was verder bloodgestel aan analises, met die hulp van spesifieke sgateware, wat gebruik maak van vergelykende algoritmes vir motief karakterisering. Vier cis-motiewe is identifiseer en kom voor in dieselfde volgorde en oriëntasie in elk van die gene. In silico voorspelling van moontlike transkripsie faktor bindingsplekke het getoon dat daar talle bindingsmotiewe van belang teenwoordig is en dié motiewe kan gekoppel word aan biologiese funksies in hierdie padweg, insluitend ‘n nuwe MTF-1 bindingsplek in vyf van die gene van belang. Die bioinformatiese analises is verder gevalideer om die relevansie van die resultate in ‘n in vitro sisteem ten volle te assesseer. Luciferase rapporteerder konstrukte is vir die nege gene ontwerp wat die volgende bevat: 1) die 2 kb promotor, 2) ‘n 1.86 kb promotor met die GA verwyder en 3) die 140 bp GA element. Die vlakke van uitdrukking van hierdie drie rapporteerder konstrukte was genormaliseer met ‘n dubbele-luciferase rapporteerder assay onder standaard kultuur kondisies en gesimuleerde ysteroorlading kondisies in twee verskillende soogdier sellyne. Resultate van die luciferase assays dui aan dat die GA promotor konstrukte statisties betekenisvolle variasie toon in vergelyking met die onbehandelde kontrole konstrukte. Verder, die GA blyk om transkipsionele regulatoriese effekte te medieer via ‘n yster-onafhanklike meganisme. Dit blyk duidelik dat die bioinformatiese voorspellings ook funksioneel getoon kon word en was dus relevant in dié studie en regverdig verdere ondersoek. Hierdie eksperimentele ontwerp verteenwoordig ‘n unieke en omvattende oorsig van nuwe transkripsionele beheer elemente wat voorkom in die yster metaboliese padweg. Die resultate van dié studie versterk die hipotese dat gene met soortgelyke promotor argitektuur en wat betrokke is in ‘n gemene padweg saam gereguleer kan word. Daarbenewens, die gekombineerde strategie wat in hierdie studie gebruik is het toepassings in alternatiewe metaboliese paaie, en kan dien as ‘n verfynde benadering vir die voorspelling en studie van die regulerende teikens in nie-koderende genomiese DNS. / National Research Foundation (Thuthuka) / Stellenbosch University

Female mosquitoes of the species, Aedes aegypti (yellow fever mosquito, Diptera), blood feed for oogenesis. Therefore, mosquitoes are exposed to high iron loads and possibly blood-borne pathogens. We are interested in studying iron metabolism in A. aegypti to find methods for controlling mosquito populations, and thereby reduce human exposure to these pathogens. First, we found that the expression of the Aedes ferritin light chain homologue (LCH) is up-regulated by blood feeding. Ferritin LCH and heavy chain homologue (HCH) genes are closely clustered together and both mRNA transcripts increase with iron and oxidative stress (H2O2 and hemin). Second, we show A. aegypti larval cells synthesize and secrete ferritin in response to iron. Cytoplasmic ferritin is maximal at low levels of iron, consists of a specific subunit composition and reflects cytoplasmic iron levels. Secreted ferritin increases in linear relationship to increasing iron dose and is composed of different subunits than cytoplasmic ferritin. HCH and LCH transcripts increase with increasing cytoplasmic iron suggesting transcriptional control of ferritin synthesis. We previously reported that the mosquito HCH mRNA has an iron responsive element (IRE), but LCH mRNA does not have a canonical IRE. We show that iron regulatory protein 1 (IRP1)/IRE binding activity declines in response to increasing cytoplasmic iron levels. These data would indicate that HCH synthesis is controlled at transcription and translation. Third, we report that A. aegypti larval cell cytoplasmic iron concentration does not change temporally with iron treatment. However, membrane iron levels increase with iron over time. Iron temporally up-regulates both HCH and LCH mRNA. Ferritin secretion increases with time in response to iron and reflects that most of the intracellular ferritin is found in the membrane fraction. Membrane ferritin has the same subunit composition as cytoplasmic ferritin. Finally, membrane ferritin is found in both non-iron and iron-treated cells. This suggests a mechanism to store iron from a blood meal in membrane ferritin. These results indicate Aedes ferritin could act as an antioxidant and holoferritin secretion is likely the mechanism whereby mosquito cells protect against iron overload and, thus reduce the intracellular potential for iron-mediated oxidative stress during blood feeding.

Iron status and dietary iron intake were examined in thirteen non-anemic menstruating competitive female cyclists training greater than 150 miles/week. Serum ferritin was 37.6 ± 49.1 ng/ml (mean ± SD), iron stores were 241 ± 92 and serum iron was 124.0 ± 64. Four subjects (30.8%) presented with iron deficiency, 30.7% had iron stores less than zero mg and 23.1% had iron stores less than -100 mg. Mean energy intake was 1625 ± 376 Kcal. Mean total iron intake (food + multivitamins) was 18.8 ± 6.9 mg/day, and absorbable iron intake was 1.5 ± 1.2 mg/day. Seven athletes (47%) consumed less than the RDA (18 mg/day) while 73% (11) consumed less than 1.8 mg/day of absorbable iron. The results suggest that insufficient iron intake, either total or absorbable, contributes to a high prevalence of iron deficiency among female cyclists.

by Maria Wan-Yin Lau Wong. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1990. / Bibliography: leaves 121-133. / SUMMARY --- p.1 / INTRODUCTION --- p.3 / Chapter CHAPTER 1 --- IRON METABOLISM --- p.7 / Chapter 1.1 --- EXCRETION --- p.7 / Chapter 1.2 --- ABSORPTION --- p.8 / Chapter 1.3 --- IRON TRANSPORT AND STORAGE --- p.11 / Chapter 1.3.1 --- TRANSFERRIN --- p.11 / Chapter 1.3.2 --- STORAGE --- p.14 / Chapter CHAPTER 2 --- DISEASES ASSOCIATED WITH IRON DEFICIENCY OR OVERLOAD --- p.16 / Chapter 2.1 --- IRON DEFICIENCY ANEMIAS --- p.16 / Chapter 2.1.1 --- NUTRITIONAL DEFICIENCY --- p.17 / Chapter 2.1.2 --- IMPAIRED ABSORPTION --- p.17 / Chapter 2.1.3 --- INCREASED IRON REQUIREMENTS --- p.18 / Chapter 2.1.4 --- INCREASED IRON LOSS --- p.19 / Chapter 2.2 --- IRON OVERLOAD --- p.20 / Chapter 2.2.1 --- INCREASED IRON ABSORPTION --- p.21 / Chapter 2.2.2 --- PARENTERAL IRON OVERLOAD --- p.25 / Chapter 2.2.3 --- FOCAL IRON DEPOSITION --- p.26 / Chapter 2.2.4 --- NEONATAL HEMOCHROMATOSIS --- p.27 / Chapter 2.2.5 --- IRON STATUS IN HONG KONG POPULATION --- p.28 / Chapter 2.2.6 --- PREVALENCE OF IRON OVERLOAD IN VARIOUS REGIONS --- p.28 / Chapter 2.3 --- IRON STORAGE DISEASE --- p.29 / Chapter CHAPTER 3 --- ASSESSMENT OF IRON OVERLOAD --- p.31 / Chapter 3.1 --- SERUM PARAMETER --- p.31 / Chapter 3.1.1 --- SERUM IRON --- p.31 / Chapter 3.1.2 --- TRANSFERRIN SATURATION --- p.31 / Chapter 3.1.3 --- SERUM FERRITIN --- p.32 / Chapter 3.2 --- NON-SERUM PARAMETER --- p.34 / Chapter 3.2.1 --- HLA TYPING --- p.34 / Chapter 3.2.2 --- HEPATIC IRON CONCENTRATION --- p.35 / Chapter 3.2.3 --- HISTOLOGICAL ASSESSMENT --- p.35 / Chapter 3.2.3(i) --- HEPATIC MORPHOLOGY --- p.36 / Chapter 3.2.4 --- NON-INVASIVE PROCEDURE --- p.38 / Chapter CHAPTER 4 --- MATERIALS AND METHODS --- p.39 / Chapter METHOD 1: --- HAEMATOXYLIN AND EOSIN STAIN --- p.43 / Chapter METHOD 2: --- PERLS' PRUSSIAN BLUE --- p.44 / Chapter METHOD 3: --- ROWE'S HISTOLOGICAL GRADING SYSTEM OF IRON DEPOSITION --- p.45 / Chapter METHOD 4: --- SEARLE'S IRON GRADING SYSTEM --- p.47 / Chapter METHOD 5: --- PARAFFIN REMOVAL --- p.48 / Chapter METHOD 6: --- CHEMICAL DETERMINATION OF IRON CONCENTRATION BY ATOMIC ABSORPTION SPECTROPHOTOMETRY --- p.49 / Chapter CHAPTER 5 --- RESULTS --- p.50 / Chapter 5.1 --- CHEMICAL DETERMINATION --- p.50 / Chapter 5.2 --- CONTROL GROUP --- p.53 / Chapter 5.3 --- HISTOLOGICAL STUDY --- p.54 / Chapter 5.3.1 --- NEONATES AND INFANTS --- p.55 / Chapter 5.3.2 --- CHILDREN AND ADOLESCENCE --- p.56 / Chapter 5.3.3 --- ADULT IRON STORAGE --- p.56 / Chapter 5.4 --- SEX DISTRIBUTION --- p.57 / Chapter 5.5 --- AGE DISTRIBUTION --- p.58 / Chapter 5.6 --- ASSOCIATION BETWEEN SIDEROSIS IN HEPATOCYTES AND KUPFFER CELLS --- p.58 / Chapter 5.7 --- ASSOCIATION OF HEPATOCYTIC IRON WITH FIBROSIS --- p.59 / Chapter 5.8 --- SYSTEMIC TISSUES --- p.59 / Chapter 5. 11 --- HEPATOCYTIC IRON DETERMINED BY SEARLE'S METHOD --- p.61 / TABLES AND FIGURES --- p.63 / Chapter CHAPTER 6 --- DISCUSSION --- p.102 / Chapter 6.1 --- CORRELATION BETWEEN HISTOLOGICAL AND CHEMICAL DETERMINATION OF IRON IN THE LIVER --- p.102 / Chapter 6.2 --- IRON CONTENT OF NEONATES --- p.105 / Chapter 6.3 --- IRON CONTENT OF THE ADOLESCENCE AND CHILDREN GROUP --- p.106 / Chapter 6.4 --- IRON CONTENT OF THE ADULT GROUP --- p.106 / Chapter 6.5 --- RELATIONSHIP OF SIGNIFICANT IRON DEPOSITION WITH SEX --- p.108 / Chapter 6.6 --- ASSOCIATION OF SIFNIFICANT IRON DEPOSITION WITH AGE --- p.108 / Chapter 6.7 --- MODE OF IRON DISTRIBUTION IN THE LIVER --- p.109 / Chapter 6.8 --- ASSOCIATION WITH FIBROSIS --- p.111 / Chapter 6.9 --- RELATIONSHIP WITH SYSTEMIC TISSUES --- p.112 / Chapter 6.10 --- THE CONTROL GROUP --- p.114 / Chapter 6.11 --- SEARLE'S IRON GRADING --- p.115 / Chapter 6.12 --- SIDEROSIS IN THE HONG KONG POPULATION --- p.116 / Chapter CHAPTER 7 --- CONCLUSION --- p.119 / REFERENCES --- p.121

Kwan Pui-Chun. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references (leaves 140-155). / Abstracts in English and Chinese. / Chapter Chapter 1 --- Introduction / Chapter 1.1 --- Overview --- p.1 / Chapter 1.2 --- Iron homeostasis --- p.5 / Chapter 1.3 --- Natural Resistance Associated Marcophage Protein (Nramp) Family --- p.15 / Chapter 1.4 --- Divalent Metal Transporter 1 (DMT1) --- p.18 / Chapter 1.5 --- Iron Responsive Element (IRE) and Iron Regulatory Protein (IRP) --- p.23 / Chapter 1.6 --- Expression and localization of DMT-1 in human --- p.27 / Chapter 1.7 --- Iron and the developing feus --- p.31 / Chapter 1.8 --- Objectives of the study --- p.36 / Chapter Chapter 2 --- Materials and Method / Chapter 2.1 --- Study population --- p.37 / Chapter 2.2 --- Procedure of surgical termination of pregnancy --- p.38 / Chapter 2.3 --- Tissues collection and preparation --- p.39 / Chapter 2.4 --- Semi-quantitative Reverse Transcription-Polymerase Chain Reaction --- p.44 / Chapter 2.5 --- Immunohistochemistry --- p.49 / Chapter 2.6 --- Statistical analysis --- p.55 / Chapter Chapter 3 --- Results / Chapter 3.1 --- Description of subjects --- p.56 / Chapter 3.2 --- Existence of human DMT-1 isoforms at early pregnancy --- p.58 / Chapter 3.3 --- Relative expression of DMT-1 isoforms to β -actin mRNA expression at different week gestation --- p.67 / Chapter 3.4 --- Cellular localization of DMT-1 isoforms at early pregnancy --- p.91 / Chapter 3.5 --- Relative expression of DMT-1 proteins at early pregnancy --- p.101 / Chapter Chapter 4 --- Discussion / Chapter 4.1 --- Existence of DMT-1 at early pregnancy --- p.116 / Chapter 4.2 --- Expression of DMT-1 isoforms at early pregnancy at gene level --- p.118 / Chapter 4.3 --- Expression of DMT-1 isoforms at early pregnancy at protein level --- p.120 / Chapter 4.4 --- "Comparison expression of DMT-1 between human fetus, human adult and animal studies" --- p.121 / Chapter 4.5 --- Functional importance of DMT-1 at developing fetus at early pregnancy --- p.130 / Chapter 4.6 --- Conclusion --- p.138 / Chapter 4.7 --- Further study --- p.139 / Chapter Chapter 5 --- Reference --- p.140 / Appendix I: Calculation of EM --- p.156