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| 2. |
- Centlow, Magnus, et al.
(författare)
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Die in-vitro Perfusion der menschlichen Plazenta mit Eryhtrozyten und Xanthine Oxidase als in vitro Simulation von Praeeklampsie.
- 2009
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Ingår i: Zeitschrift für Geburtshilfe und Neonatologie. - : Georg Thieme Verlag KG. - 0948-2393 .- 1439-1651. ; 213:3, s. 89-95
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND AND PURPOSE: Preeclampsia is a major obstetric problem of unknown etiology. The fact that removal of the placenta is the only cure for preeclampsia, has led to the well-established hypothesis, that the placenta is central in the etiology. Gene profiling and proteomics studies have suggested oxidative stress caused by reperfusion and free oxygen radicals as a potential pathophysiological mechanism in preeclampsia. In this study, the dual placental perfusion model was used in order to evaluate the damaging effects of oxidative stress induced by xanthine/xanthine oxides and free hemoglobin.MATERIAL AND METHODS: The dual placenta perfusion model is a well-established in vitro model for functional placental studies. Placentas were perfused with medium containing either xanthine/xanthine oxidase or erythrocytes as a source of free hemoglobin. Concentration of free hemoglobin in the medium was measured by means of ELISA. Whole genome microarray technique and bioinformatics were used to evaluate the gene expression profile in the two groups.RESULTS: Substantial levels of free adult hemoglobin were detected in the perfusions. A total of 58 genes showed altered gene expression, the most altered were hemoglobin alpha, beta and gamma, tissue factor pathway inhibitor 2 and superoxide dismutase 2. Bioinformatics revealed that biological processes related to oxidative stress, anti-apoptosis and iron ion binding were significantly altered.CONCLUSIONS: The results suggest that perfusion with xanthine/xanthine oxidase and free hemoglobin induce changes in gene expression similar to what has been described for the preeclamptic placenta.
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| 3. |
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| 4. |
- Gram, Magnus, et al.
(författare)
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The lipocalin alpha1-microglobulin protects erythroid K562 cells against oxidative damage induced by heme and reactive oxygen species.
- 2008
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Ingår i: Free Radical Research. - : Informa UK Limited. - 1029-2470 .- 1071-5762. ; 42:8, s. 725-736
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Tidskriftsartikel (refereegranskat)abstract
- Alpha(1)-microglobulin is a 26 kDa plasma and tissue glycoprotein that belongs to the lipocalin protein superfamily. Recent reports show that it is a reductase and radical scavenger and that it binds heme and has heme-degrading properties. This study has investigated the protective effects of alpha(1)-microglobulin against oxidation by heme and reactive oxygen species in the human erythroid cell line, K562. The results show that alpha(1)-microglobulin prevents intracellular oxidation and up-regulation of heme oxygenase-1 induced by heme, hydrogen peroxide and Fenton reaction-generated hydroxyl radicals in the culture medium. It also reduces the cytosol of non-oxidized cells. Endogeneous expression of alpha(1)-microglobulin was up-regulated by these oxidants and silencing of the alpha(1)-microglobulin expression increased the cytosol oxidation. alpha(1)-microglobulin also inhibited cell death caused by heme and cleared cells from bound heme. Binding of heme to alpha(1)-microglobulin increased the radical reductase activity of the protein as compared to the apo-protein. Finally, alpha(1)-microglobulin was localized mainly at the cell surface both when administered exogeneously and in non-treated cells. The results suggest that alpha(1)-microglobulin is involved in the defence against oxidative cellular injury caused by haemoglobin and heme and that the protein may employ both heme-scavenging and one-electron reduction of radicals to achieve this.
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| 5. |
- Gram, Magnus, et al.
(författare)
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Up-regulation of alpha(1)-microglobulin by hemoglobin and reactive oxygen species in hepatoma and blood cell lines.
- 2007
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Ingår i: Free Radical Biology & Medicine. - : Elsevier BV. - 0891-5849. ; 42:6, s. 842-851
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Tidskriftsartikel (refereegranskat)abstract
- alpha(1)-Microglobulin is a 26-kDa glycoprotein synthesized in the liver, secreted to the blood, and rapidly distributed to the extravascular compartment of all tissues. Recent results show that alpha(1)-microglobulin has heme-binding and heme-degrading properties and it has been suggested that the protein is involved in the defense against oxidation by heme and reactive oxygen species. In the present study the influence of hemoglobin and reactive oxygen species (ROS) on the cellular expression of alpha(1)-microglobulin was investigated. Oxy- and methemoglobin, free heme, and Fenton reaction-induced hydroxyl radicals induced a dose-dependent up-regulation of alpha(1)-microglobutin on both mRNA and protein levels in hepatoma cells and an increased secretion of alpha(1)-microglobulin. The up-regulation was reversed by the addition of catalase and ascorbate, and by reacting hemoglobin with cyanide which prevents redox reactions. Furthermore, the blood cell lines U937 and K562 expressed alpha(1)-microglobulin at low levels, and this expression increased up to 11-fold by the addition of hemoglobin. These results suggest that a-l-microglobulin expression is induced by ROS, arising from redox reactions of hemoglobin or from other sources and are consistent with the hypothesis that alpha(1)-microglobulin participates in the defense against oxidation by hemoglobin, heme, and reactive oxygen species. (c) 2007 Elsevier Inc. All rights reserved.
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| 6. |
- Kwasek, Anna, et al.
(författare)
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Production of recombinant human alpha(1)-microglobulin and mutant forms involved in chromophore formation
- 2007
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Ingår i: Protein Expression and Purification. - : Elsevier BV. - 1046-5928. ; 53:1, s. 145-152
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Tidskriftsartikel (refereegranskat)abstract
- alpha-Microglobulin, a 26 kDa lipocalin present in plasma and tissues, carries a set of unknown chromophores, bound to C34, K92, KI 18 and KI 30, which cause its charge and size heterogeneity. In man, the protein is found in two forms, full length and lacking the C-terminal tetrapeptide LIPR (t-alpha(1)-microglobulin), both which are heme-binding and the latter with heme-degrading properties. We report cloning and overexpression of full length alpha(1)-microglobulin (wt protein), t-alpha(1)-microglobulin (wtz LIPR) and the mutants C34S, K(92,118,130)T and C34S/K(92,118,130)T, the latter subsequently abbreviated as K(3)T and C34S/K(3)T, in Escherichia coli. After purification and refolding from inclusion bodies, all proteins were correctly folded as determined by far-UV circular dichroism and radioimmunoassay. As revealed by gel filtration, recombinant alpha(1)-microglobulins had lower tendencies to form dimers than human plasma or urine analogues. All alpha(1)-microglobulin forms displayed higher amounts of the chromophore than bovine serum albumin but significantly lower than the human urine or plasma counterparts. Differences in the absorbance and fluorescence profiles are consistent with a model where the chromophore is formed by a series of reactions with heme or other chromophore precursors and where C34 is essential for binding of the ligand, K92, KI 18 and K130 are involved in transformation into the chromophore and LIPR inhibits the latter reaction. (c) 2006 Elsevier Inc. All rights reserved.
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| 7. |
- Larsson, Mårten, 1972-
(författare)
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Megalin, an Endocytotic Receptor with Signalling Potential
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Megalin is an endocytotic receptor belonging to the low-density lipoprotein family. It has often been viewed only as merely a scavenger receptor of absorptive and secretory epithelia. Recent work has revealed that the megalin intracellular domain contains several motifs potentially binding proteins involved in signal transduction.To find potential intracellular proteins binding to megalin, a yeast two-hybrid screening was initiated with the intracellular tail of megalin as the bait. A partial clone encoding the scaffolding protein postsynaptic protein 95 (PSD-95) was found to bind to megalin with its second PDZ-domain. Co-localization experiments in HEK-293 cells and kidney, placenta and parathyroid tissue confirmed this interaction. The PSD-95 related proteins PSD-93 and SAP102 were also confirmed to bind megalin with their PDZ2-domains, but the corresponding domain from SAP97 did not bind. Mutation analysis revealed that an amino acid residue change Ala to Thr was the cause of this.Megalin has within the central nervous system (CNS) been shown to be expressed only in the ependymal cells and choroid plexus. Nothing has been known about megalin expression in the spinal cord. To study spatio-temporal expression of megalin in the spinal cord, extensive staining of prenatal and postnatal mouse spinal cord was undertaken. Megalin expression was found in the dorsal part of the embryonic spinal cord. Most of these cells also expressed vimentin, suggesting that megalin has a role in the normal development of astrocytes. In the postnatal mouse, megalin seems to be expressed in oligodendrocytes only in the spinal cord white matter, and co-incident with myelination. This suggests that megalin is involved in the formation and maintenance of myelin along long spinal pathways. Megalin staining was clearly seen in the nucleus of these cells, indicating that megalin works in a notch-like signalling pathway.Uptake of retinol to the retina pigment epithelium (RPE) has long been thought to be a diffusion process. Staining for megalin in RPE revealed strong expression, and uptake experiments with 3H-retinol bound to retinol-binding protein and blocking with the LDL-receptor family specific antagonist receptor-associated protein (RAP) showed that megalin is a receptor for uptake of retinol to the RPE.
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| 8. |
- Lindberg, Daniel, 1974-
(författare)
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Molecular Genetic Studies of Sporadic and MEN1-Associated Endocrine Pancreatic Tumors
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Pancreatic endocrine tumors (PETs) may cause typical syndromes of hormone excess, or appear clinically non-functioning without hormonal symptoms. PETs occur sporadically, in association with the multiple endocrine neoplasia type 1 (MEN1) syndrome, or rarely the von Hippel-Lindau syndrome. Molecular genetic investigations may reveal pathways important for tumor development, and be of clinical use.The aim of this thesis was to investigate regulation of different genes involved in cell proliferation, and relate findings to signs of malignancy in PETs.The MEN1 gene on chromosome 11q13 was mutated in three out of eleven sporadic malignant PETs. Two nonsense mutations, causing truncation of the protein, and one missense mutation were found.Relation of allelic loss at 11q13 and 3p25 to malignant behavior was observed in sporadic PETs. Allelic loss at 18q21 was found in a subset of sporadic and MEN1-associated PETs, and mutation analysis of Smad4 excluded a tumor suppressor gene function.In PETs with allelic loss on chromosome 3p25, mutation analysis of WNT7A and HDAC11 excluded function as tumor suppressor genes.Menin, encoded by the MEN1 gene, was reported to regulate expression of the cyclin-dependent kinase inhibitors CDKN2C/p18, CDKN1B/p27, and CDKN2B/p15 in mouse pancreatic islet tumor models. Here, the mRNA expression of these genes was not related to MEN1 gene mutations in human PETs.Cyclin-dependent kinase 4 (CDK4) and the protooncogene c-Myc were found to be overexpressed regardless of MEN1 gene mutational status of the PETs. The CDK4 gene was neither amplified nor mutated. Targeting of CDK4 may present an alternative to traditional chemotherapy of PETs in the future.
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| 9. |
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Lipocalins
- 2006
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Samlingsverk (redaktörskap) (övrigt vetenskapligt/konstnärligt)abstract
- Less than a decade has elapsed since the publication in 2000 of the first anthology devoted to lipocalins (Biochim Biophys Acta 1482, 2000), and only a few years since the first Lipocalin International Symposium in Copenhagen in 2003 (Benzon Symposium no. 50 “The Lipocalin Protein Superfamily,” Copenhagen, 2003) and the introduction of a public lipocalin website (http://www.jenner.ac.uk/lipocalins.htm). In spite of all these recent joint actions from the lipocalin community, the need for another anthology has been expressed. Many new exciting publications have been issued during the past five years, partially outdating the 2000 BBA lipocalin anthology. Likewise, the three events mentioned above have undoubtedly had a positive effect upon lipocalin research and the exchange of research information. As a result the community of lipocalin researchers is highly motivated to continue such pan-lipocalin activities. Several of the chapters in this volume are reviews of groups of lipocalins with a similar phylogenetic or tissue distribution (Chapters 4-6, 12 and 13). Furthermore, two chapters discuss the evolutionary and structural relationships between the lipocalins (Chapters 2 and 3) and the penultimate three chapters are treatises on themes in lipocalin research: receptors, allergy, and clinical diagnosis (Chapters 14-16); the final chapter discusses how lipocalin research might go in future.
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| 10. |
- Lögdberg, Bengt, et al.
(författare)
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Lipocalins in clinical medicine
- 2006
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Ingår i: Lipocalins. - 9781587062971 ; , s. 187-187
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Bokkapitel (populärvet., debatt m.m.)
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