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Biomedical subjects

U Eriksson

Publications and source records attributed to U Eriksson.

At least 73 records · Page 4Linked to original sources
PubMed1997

In vitro effects of inogatran, a selective low molecular weight thrombin inhibitor.

The thrombin inhibitor inogatran is a synthetic peptidomimetic with a molecular weight of 439 dalton. In vitro studies have shown that inogatran is a classical competitive inhibitor of the active site of thrombin with a Ki of 15 x 10(-9) mol/l. Inogatran doubles the thrombin clotting time in human plasma at 20 x 10(-9) mol/l, APTT at 1.2 x 10(-6) mol/l, and prothrombin time at 4 x 10(-6) mol/l. The effects on rat and dog plasma are similar although slightly weaker. IC50 for inhibition of thrombin-induced aggregation of human platelets is 17 x 10(-9) mol/l. Inogatran has no effect on platelet aggregation induced by ADP or collagen. Up to a concentration of 10 x 10(-6) mol/l inogatran does not inhibit t-PA-induced fibrinolysis as seen in an ECLT system. Inogatran has good selectivity for thrombin as compared to several other serine proteases occurring in the blood. It is concluded that the properties of inogatran in vitro make the compound suitable for further studies in animals and man.

Adenosine Diphosphate↗
PubMed1997

Retinoid binding proteins in mouse yolk sac and chorio-allantoic placentas.

In the adult, as well as in the embryo, a number of specific extra- and intracellular binding proteins such as the plasma retinol binding protein (RBP), the cellular retinol binding protein type I (CRBP I), and also the cellular receptors for RBP are thought to regulate transport and metabolism of retinol (vitamin A). Since the regulation of materno-fetal transport of vitamin A is not well understood, we examined the localization of these proteins during the development of the mouse chorio-allantoic and yolk sac placentas. The labyrinthine region of the chorio-allantoic placenta, where exchange of substances can occur between the maternal and fetal circulations, did not contain RBP (mRNA or protein) or antigen(s) similar to the bovine RBP-receptor p63, whereas the visceral endoderm of the yolk sac placenta, the second site for materno-fetal transport, did. Furthermore, only the endodermal cells of the visceral yolk sac appeared to strongly accumulate radiolabelled retinoids. The cellular retinol binding protein (CRBP I) was detected both in the trophoblast layer of the placental labyrinth closest to the fetal endothelium (layer III), and in the visceral endoderm of the yolk sac. Together, these findings suggest that the yolk sac placenta mediates retinol transfer to the embryo/fetus throughout the entire gestation. The chorio-allantoic placenta, on the other hand, does not appear to have this capacity, while the presence of CRBP I does suggest a retinol-metabolizing capability.

Animals↗
PubMed1997

The Swedish Environmental Specimen Bank--application in trend monitoring of mercury and some organohalogenated compounds.

The Environmental Specimen Bank (ESB) at the Swedish Museum of Natural History, Stockholm, constitutes a base for ecotoxicological research as well as for spatial and trend monitoring of contaminants in Swedish fauna. Since the 1960s, tissue samples from more than 150000 organisms have been collected from different groups of animals, habitats and types of landscape. Samples from the ESB have been utilized for retrospective studies of trace elements, organohalogenated compounds and radionuclides. Among many matrices utilized, eggs of guillemot (Uria aalge) have proven to be an appropriate matrix for assessment of the contamination of the Baltic Sea. Results from time trend studies based on this material showing trends in concentrations of DDT, PCB, PCDD/F, and mercury are presented in this paper.

Animals↗
PubMed1997

Purification and characterization of substance P endopeptidase activities in the rat spinal cord.

Two enzymes with substance P degrading activity were purified from the membrane bound fraction of the rat spinal cord. The purified enzymes were characterized with regard to biochemical and kinetic properties. One of the enzymes exhibited close similarity to neutral endopeptidase 24.11 (NEP, EC 3.4.24.11), while the other resembled a substance P converting endopeptidase (SPE), which has previously been identified and purified from human cerebrospinal fluid (CSF). Detergent treated spinal cord homogenates from male Sprague Dawley rats were purified by anion-exchange chromatography (DEAE-sepharose CL-6B), hydrophobic-interaction chromatography (phenyl-sepharose CL-4B) and molecular sieving (Sephadex G-50). Two fractions with enzymes differing in size were recovered and allowed for further purification to apparent homogeneity by ion-exchange chromatography and molecular sieving on a micro-purification system (SMART). The enzyme activities were monitored by following the conversion of synthetic substance P using a radioimmunoassay specific for the heptapeptide product, substance P (1-7). By SDS-polyacrylamide gel electrophoresis of the purified enzymes molecular weights of 43 and 70 kDa were estimated for the SPE-like and NEP-like activity, respectively. A K(m) of 5 microM was determined for the conversion of substance P to its (1-7) fragment by the SPE-like activity. Reversed-phase HPLC together with mass spectrometry permitted identification of all fragments released from substance P by the peptidases. The released fragments were for both enzymes identified as substance P (1-7), substance P (8-11), substance P (1-8), substance P (9-11). The NEP-like enzyme preparation also gave substance P (1-6) as a major product.

Animals↗
PubMed1997

Detection of Francisella tularensis in ulcers of patients with tularemia by PCR.

The diagnosis of human cases of tularemia is usually confirmed by the demonstration of an antibody response to Francisella tularensis, which occurs about 2 weeks after the onset of disease. Due to a high risk of infection in the laboratory, cultivation of the causative agent tends to be avoided. During an outbreak in Sweden, the use of PCR for diagnosing the ulceroglandular form of tularemia was evaluated. Extraction and preparation of F. tularensis DNA from swab samples from the wounds of patients with tularemia involved the use of the nuclease inhibitor guanidine thiocyanate. The DNA was detected by multiplex PCR targeting the 16S rRNA gene and a 17-kDa lipoprotein gene of F. tularensis. In 29 of 40 (73%) patients with serologically confirmed tularemia, F. tularensis DNA was successfully amplified. Considering the limitations of current diagnostic procedures, PCR may become useful for the early diagnosis of tularemia.

Adolescent↗
PubMed1996

Primary structure of human 11-cis retinol dehydrogenase and organization and chromosomal localization of the corresponding gene.

The universal chromophore of visual pigments in higher animals is 11-cis retinaldehyde. The final step in the biosynthetic pathway generating this compound is catalyzed by 11-cis retinol dehydrogenase, a membrane-bound enzyme abundantly expressed in the retinal pigment epithelium of the eye. In this work we demonstrate that the primary structure of human 11-cis retinol dehydrogenase is highly conserved with 91% identity to the bovine enzyme. The gene encoding 11-cis retinol dehydrogenase spans over approximately 4.1 kb of DNA and is divided into four translated exons. Analysis of a panel of somatic cells hybrids and fluorescence in situ hybridization on metaphase chromosomes revealed that the gene is located on chromosome 12q13-q14. Due to the unique role of 11-cis retinol dehydrogenase in the generation of visual pigments, it is a candidate gene for involvement in hereditary eye disease.

Alcohol Oxidoreductases↗
PubMed1996

Reversed-phase high-performance liquid chromatography combined with tandem mass spectrometry in studies of a substance P-converting enzyme from human cerebrospinal fluid.

The application of reversed-phase HPLC in combination with micro-electrospray mass spectrometry to study a substance P (SP)-hydrolysing endoprotease in human cerebrospinal fluid (hCSF) is reported. The enzyme was partially purified from the hCSF specimens by ion-exchange chromatography and molecular sieving. During the purification procedure the enzyme activity was monitored by measuring the formation of the SP-fragment 1-7 from SP by radioimmunoassay. Regarding its behaviour upon molecular sieve chromatography, the enzyme was suggested to be associated with an apparent molecular mass of around 100 x 10(3). In subsequent experiments using the partially purified endopeptidase, the hydrolysis of SP was demonstrated by HPLC. The reaction product mixture was resolved in several components including the N-terminal fragments 1-8, 1-7 and 1-6 and the C-terminal fragment 8-11. The identity of these fragments were confirmed by tandem mass spectrometry. It was concluded that the present SP-degrading enzyme is different from those previously identified and purified from hCSF. The applied techniques were proven to be highly efficient for the recovery and identification of the released peptide products.

Animals↗
PubMed1996

Genomic organization of the mouse and human genes for vascular endothelial growth factor B (VEGF-B) and characterization of a second splice isoform.

A second isoform and the genomic structures of mouse and human vascular endothelial growth factor B are described. Both genes consist of seven coding exons and span about 4 kilobases of DNA. The two identified isoforms of vascular endothelial growth factor B are generated by alternative splicing where different splice acceptor sites in exon 6 introduce a frameshift and a partial use of different but overlapping reading frames. Consequently, the COOH-terminal domains in the two isoforms show no resemblance. Mouse and human cDNA clones for the novel isoform of vascular endothelial growth factor B encoded a secreted protein of 186 amino acid residues. Expression in transfected cells generated a protein of 25 kDa which upon secretion was modified by O-linked glycosylation and displayed a molecular mass of 32 kDa under reducing conditions. The protein was expressed as a disulfide-linked homodimer, and heterodimers were generated when coexpressed with vascular endothelial growth factor. The entirely different COOH-terminal domains in the two isoforms of vascular endothelial growth factor B imply that some functional properties of the two proteins are distinct.

Amino Acid Sequence↗
PubMed1996

Vascular endothelial growth factor B, a novel growth factor for endothelial cells.

We have isolated and characterized a novel growth factor for endothelial cells, vascular endothelial growth factor B (VEGF-B), with structural similarities to vascular endothelial growth factor (VEGF) and placenta growth factor. VEGF-B was particularly abundant in heart and skeletal muscle and was coexpressed with VEGF in these and other tissues. VEGF-B formed cell-surface-associated disulfide-linked homodimers and heterodimerized with VEGF when coexpressed. Conditioned medium from transfected 293EBNA cells expressing VEGF-B stimulated DNA synthesis in endothelial cells. Our results suggest that VEGF-B has a role in angiogenesis and endothelial cell growth, particularly in muscle.

Amino Acid Sequence↗
PubMed1996

Novel human vascular endothelial growth factor genes VEGF-B and VEGF-C localize to chromosomes 11q13 and 4q34, respectively.

BACKGROUND: Vascular endothelial growth factor (VEGF) is an important regulator of endothelial cell proliferation, migration, and permeability during embryonic vasculogenesis as well as in physiological and pathological angiogenesis. The recently isolated VEGF-B and VEGF-C cDNAs encode novel growth factor genes of the VEGF family. METHODS AND RESULTS: Southern blotting and polymerase chain reaction analysis of somatic cell hybrids and fluorescence in situ hybridization (FISH) of metaphase chromosomes were used to assess the chromosomal localization of VEGF-B and VEGF-C genes. The VEGF-B gene was found on chromosome 11q13, proximal to the cyclin D1 gene, which is amplified in a number of human carcinomas. However, VEGF-B was not amplified in several mammary carcinoma cell lines containing amplified cyclin D1. The VEGF-C gene was located on chromosome 4q34, close to the human aspartylglucosaminidase gene previously mapped to 4q34-35. CONCLUSIONS: The VEGF-B locus in 11q13 and the VEGF-C locus in 4q34 are candidate targets for mutations that lead to vascular malformations or cardiovascular diseases.

Base Sequence↗
PubMed1996

Nuclear import of cellular retinoic acid-binding protein type I in mouse embryonic cells.

Using confocal microscopy we show that cellular retinoic acid-binding protein type I (CRABP I), expressed in several embryonic cell types, displays a compartmentalized subcellular distribution. The protein was excluded from the nucleus in some cells, while in others it accumulated in the nucleus. In the rat cerebellar cell line ST15A, which expresses CRABP I, the protein was found in the cytoplasm with a prominent nuclear exclusion. Addition of retinoic acid to embryos in vivo and to ST15 A cells in vitro did not affect the localization of the protein. Localization of CRABP I and CRABP I fused to a nuclear localization signal expressed in transfected cells, suggested that cell-specific factors may regulate nuclear import of CRABP I. The potential role of a CRABP I-controlled nuclear import of retinoic acid is discussed.

Animals↗
PubMed1996

Clinical outcome in four children with metachromatic leukodystrophy treated by bone marrow transplantation.

Four children with metachromatic leukodystrophy (MLD) underwent allogeneic bone marrow transplantation between 1988 and 1993. No effect on the natural course of the disease was observed in two children with late infantile and juvenile MLD. They had moderate neurological symptoms at the time of BMT and were followed for 7 and 6 years, respectively. The third child with the juvenile form of MLD was mildly to moderately affected when transplanted. She had lost some gross motor functions as well as speech and mental abilities at follow-up 3 years later. The fourth case, diagnosed biochemically and presymptomatically as late infantile MLD, had a subtle gait disturbance when grafted at 18 months of age. Demyelination, not observed before BMT, was visualized 1 year later on MRI. This boy's condition has continued to deteriorate 2 years after transplantation. We have adopted recent recommendations that BMT should be considered only in presymptomatic children with late infantile MLD or early in the course of juvenile MLD. In such children, still longer follow-up periods are necessary to evaluate the benefit of BMT.

Bone Marrow Transplantation↗
PubMed1995

Epitope mapping of a monoclonal antibody that blocks the binding of retinol-binding protein to its receptor.

To define the receptor binding site of retinol-binding protein (RBP) we have generated monoclonal antibodies (mAbs) to human RBP and examined their ability to interfere with the receptor binding. MAbs to two conserved regions efficiently blocked the binding. No major conformational changes in the protein occurred upon mAb binding, since the mAbs could co-immunoprecipitate the RBP-transthyretin (TTR) complex. One blocking mAb showed reactivity to a synthetic peptide corresponding to one entrance loop of the retinol-binding pocket (amino acid residues 60-70). Thus, our results show that at least one of the entrance loops of the barrel of RBP is located in or close to the receptor binding site. It can also be concluded that the receptor and TTR binding sites involve different regions of RBP.

Antibodies, Monoclonal↗
PubMed1995

The retinal pigment epithelial-specific 11-cis retinol dehydrogenase belongs to the family of short chain alcohol dehydrogenases.

We have isolated and partially characterized a 32-kDa membrane-associated protein (p32), which forms a complex with p63, an abundant membrane protein in bovine retinal pigment epithelium. The sequence of a cDNA clone for p32 revealed an open reading frame encoding 318 amino acid residues. Several hydrophobic regions could be identified, suggesting that p32 is an integral membrane protein. A search of data bases identified p32 as a member of the superfamily of short chain alcohol dehydrogenases. Transcripts for p32 were specifically expressed in retinal pigment epithelium. Overexpression of p32 in Cos cells produced a membrane-bound stereospecific 11-cis retinol dehydrogenase, active in the presence of NAD+ as cofactor but not in the presence of NADP. We propose that p32 is the stereospecific 11-cis retinol dehydrogenase, which catalyzes the final step in the biosynthesis of 11-cis retinaldehyde, the universal chromophore of visual pigments.

Alcohol Oxidoreductases↗
PubMed1995

Retinol-binding protein mediates uptake of retinol to cultured human keratinocytes.

Retinol (vitamin A) circulates in the blood bound to retinol-binding protein (RBP). The process by which target cells acquire retinol is not fully elucidated, although a cell surface receptor for RBP has recently been identified. We show here that retinol is at least an order of magnitude more efficient at blocking the terminal differentiation of cultured normal human keratinocytes when administered as a complex with RBP than when administered free in solution. This inhibition of differentiation by RBP can be reversed by monoclonal antibody P142, reactive toward the RBP-binding membrane protein p63. These results demonstrate, at least in this in vitro system, the importance of the RBP receptor in the generation of a cellular response to retinol.

Cell Differentiation↗
PubMed1995

The cellular retinoic acid binding proteins.

The two cellular retinoic acid binding proteins, CRABP I and CRABP II, belong to a family of small cytosolic lipid binding proteins and are highly conserved during evolution. Both proteins are expressed during embryogenesis, particularly in the developing nervous system, craniofacial region and limb bud. CRABP I is also expressed in several adult tissues, however, in contrast, CRABP II expression appears to be limited to the skin. It is likely that these proteins serve as regulators in the transport and metabolism of retinoic acid in the developing embryo and throughout adult life. It has been proposed that CRABP I sequesters retinoic acid in the cytoplasm and prevents nuclear uptake of retinoic acid. A role in catabolism of retinoic acid has also been proposed. Recent gene targeting experiments have shown that neither of the two CRABPs are essential for normal embryonic development or adult life. Examination of CRABP I expression at subcellular resolution reveals a differential cytoplasmic and/or nuclear localization of the protein. A regulated nuclear uptake of CRABP I implies a role for this protein in the intracellular transport of retinoic acid. A protein mediated mechanism which controls the nuclear uptake of retinoic acid may play an important role in the transactivation of the nuclear retinoic acid receptors.

Amino Acid Sequence↗