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Biomedical subjects

I Olsson

Publications and source records attributed to I Olsson.

At least 19 recordsLinked to original sources
PubMed1992

The receptors for regulatory molecules of hematopoiesis.

Proliferation and differentiation of hematopoietic cells are controlled by pleiotropic regulatory molecules. While the sequences of these factors are not related, their membrane receptors are restricted to two gene families with homologous domains. The members of the hematopoietic (or cytokine) receptor family (for erythropoietin, interleukins-2, -3, -4, -6 andu-7, granulocyte-macrophage and granulocyte colony-stimulating factor) are composed of multiple subunits necessary for high-affinity binding and cell signalling. Signal transducing mechanisms are largely unknown. The occurrence of variant signal transducers in different tissues could explain the pleiotropy of these regulatory molecules. Members of the receptor tyrosine kinase family bind dimeric forms of macrophage colony-stimulating factor, stem cell factor and platelet-derived growth factor leading to kinase activation and phosphorylation of many substrates involved in production of second messengers. Soluble forms (binding proteins) exist for members of both families. These may be proteolytic cleavage products of transmembrane receptors or naturally secreted products. Such binding proteins can potentially function as inhibitors in feedback regulation and in protection and transport of cytokines and would provide a rational therapy when cytokines are produced in excess. Knowledge of signal transduction mechanisms and of the three-dimensional structure of ligands and receptors can lead to the design of drugs with cell-specific effects.

Animals↗
PubMed1992

Roxithromycin in Lyme borreliosis: discrepant results of an in vitro and in vivo animal susceptibility study and a clinical trial in patients with erythema migrans.

A new semisynthetic macrolide roxithromycin was evaluated for its potential use in the treatment of Lyme borreliosis. Using a macro-dilution broth technique, Borrelia burgdorferi was shown to be susceptible to roxithromycin with a minimal bactericidal concentration (MBC) of 0.06-0.25 microgram/ml. A systemic B. burgdorferi infection was established in gerbils; a dosage of greater than or equal to 25 mg/kg/day roxithromycin for 10 days eliminated the infection. A single blind, randomized multicenter study was performed to evaluate the efficacy of roxithromycin 150 mg b.i.d. versus phenoxymethyl-penicillin 1 g b.i.d. for 10 days in patients with uncomplicated erythema migrans. The study was interrupted when 19 patients had enrolled because of five treatment failures. All 5 patients had received roxithromycin; three patients had persisting or recurrent erythema migrans, one developed a secondary erythema migrans-like lesion and severe arthralgia and one developed neuroborreliosis. B. burgdorferi was isolated from skin biopsies after roxithromycin therapy from two patients with persistent erythema migrans and both isolates were still highly susceptible to roxithromycin (MBC = 0.03 microgram/ml). No treatment failures were seen in 10 patients treated with phenoxymethyl-penicillin. Roxithromycin is thus not recommended for treatment of Lyme borreliosis.

Adult↗
PubMed1992

Involvement of an Asn/Val cleavage site in the production of a soluble form of a human tumor necrosis factor (TNF) receptor. Site-directed mutagenesis of a putative cleavage site in the p55 TNF receptor chain.

Soluble forms of receptors for tumor necrosis factor (TNF) might be important for regulating the actions of TNF. Site-directed in vitro mutagenesis was employed to examine the processing of the p55 tumor necrosis factor receptor chain (TNF-R55) into soluble TNF-binding protein (TNF-R55-BP). An Asn/Val sequence close to the transmembrane region in TNF-R55 was indicated as a putative cleavage site for proteolytic processing. By mutagenesis, Asn and Val were replaced with Gly and Ala, respectively. Expression in Chinese hamster ovary (CHO) cells resulted in identical binding of ligand to mutated receptors as compared to receptors not subjected to mutagenesis. Turnover rates of receptors as judged by disappearance of TNF binding capacity after inhibition of de novo protein synthesis and downregulation in response to incubation with phorbol esters were also identical between wild-type and mutated receptors. However, mutations of the cleavage site resulted in a decreased spontaneous and phorbol ester-induced release of soluble receptor (TNF-R55-BP) which was almost abolished when both Asn and Val were mutated. Our results clearly demonstrate the importance of an Asn/Val sequence for proteolytic processing of the TNF-R55 into soluble TNF-R55-BP and indicate that phorbol ester-induced downregulation of the TNF-R55 may be dissociated from proteolytic cleavage of the receptor.

Animals↗
PubMed1991

An alloimmunized, thrombocytopenic patient successfully transfused with acid-treated, random-donor platelets.

Alloimmunized, thrombocytopenic patients, refractory to random-donor platelet transfusion, often respond to HLA-identical single-donor platelets. HLA-compatible platelets are expensive, take time to prepare, and donors are sometimes not to be found. We have used random-donor platelets and 'peeled' the HLA-antigen off the platelets, using a modified laboratory method (incubation of platelets with citric acid solution at 0 degrees C). Platelet recovery in two healthy subjects was 72.0% for acid-treated platelets, and 73.5% for untreated control platelets, using 111In-labelled autologous platelets. Survival time (multiple hit) was 6.25 and 7.95 d, respectively. Random-donor platelets that were strongly positive in the crossmatch with serum from a patient became negative after treatment with the acid solution. Furthermore, transfusion of these platelets gave a post-transfusion, platelet-count increment comparable with transfusion of HLA-compatible single-donor platelets.

Blood Component Transfusion↗
PubMed1991

Epidemiology of absence epilepsy. III. Clinical aspects.

Absence epilepsy was studied in a Swedish population, aged 0-15 years, in 1978-1982. Cases were selected by electroencephalographic criteria. In the 134 children with 3 Hz spike-and-wave discharges, 97 (72.4%) had absences alone or in combination with generalized tonic-clonic seizures (grand mal): 56 had absences alone, 31 absences followed by grand mal, and 10 started with initial grand mal. Two distinct groups could be discerned: 1) childhood absence epilepsy: onset before the age of 12, with a quick response to therapy, little or no risk of grand mal, and a high remission rate; 2) juvenile absence epilepsy: onset at the age of 12 or later, a very high risk of grand mal, and usually a good response to therapy, but a high risk of relapses at withdrawal. This classification of absence epilepsy into subgroups may be useful for prognostic guidelines.

Adolescent↗
PubMed1991

Epidemiology of absence epilepsy. II. Typical absences in children with encephalopathies.

A population-based study of absence epilepsy in Swedish children, aged 0-15 years, comprised cases selected on the basis of EEG criteria. Absence epilepsy was found in 119 of the 134 children with 3 Hz spike-and-wave discharges, and 12 of these 119 (10.1%) had typical absences in addition to other generalized seizures and slow irregular spike-and-wave activity on the EEG. The mean annual incidence of this type of absence epilepsy was 0.7/100,000. The median age at onset of absences was 6 years. Eight of the 12 patients had neurological abnormalities and/or severe mental retardation. The patients constitute a heterogeneous group of encephalopathies. They may have a genetic predisposition for absence epilepsy, causing it to appear during the course of a more severe, encephalopathy related, type of epilepsy.

Adolescent↗
PubMed1991

On the binding of tumor necrosis factor (TNF) to heparin and the release in vivo of the TNF-binding protein I by heparin.

Tumor necrosis factor (TNF), a protein released by activated macrophages, is a central mediator of the host response to infection and inflammation. The TNF-binding protein I (TNF-BP-I) is a soluble fragment of the p60 transmembrane TNF receptor and an antagonist to TNF. The level of serum TNF-BP-I was found to be increased in patients with renal insufficiency as a result of a decrease in the glomerular filtration rate. During hemodialysis of patients with renal failure there was a rapid but transient increase in serum TNF-BP-I. This increase was found to be caused by heparin given before dialysis and a similar dose-dependent response to heparin was observed also in healthy individuals. The finding of a repeated release of TNF-BP-I into the circulation with intermittent injections of heparin indicates that TNF-BP-I is present both in a storage pool and in a circulating pool. The mechanism for the heparin-mediated release of TNF-BP-I was not explained; TNF-BP did not show affinity for heparin. On the other hand, TNF was found to have affinity for heparin and it could also be dissociated from heparin by TNF-BP-I. It is suggested that heparin-like molecules of the extracellular matrix can retain TNF in physical proximity with target cells and restrict the actions of TNF and protect against systemic harmful manifestations.

Carrier Proteins↗
PubMed1991

Comparison of four different serological methods for detection of antibodies to Borrelia burgdorferi in erythema migrans.

Three different enzyme-linked immunosorbent assays (ELISA) and Western blot were compared in regard to the detection of antibodies to Borrelia burgdorferi in sera from 100 patients with erythema migrans and from 100 controls. For IgG detection, a commercial indirect ELISA kit with flagellum antigen (flagellum ELISA) was significantly more sensitive than the routinely-used indirect ELISA with sonicated whole-cell antigen (sonicate ELISA) (p = 0.008). The difference in positivity in the IgM test was of borderline significance (p = 0.058). An IgM antibody-capture ELISA with sonicated whole-cell antigen (capture ELISA) was significantly more sensitive than either the IgM sonicate ELISA (p less than 0.001) or IgM flagellum ELISA (p less than 0.001). With the Western blot pattern chosen as the criterion for positivity, IgM Western blot was at least equal to IgM capture ELISA in terms of the number of positive erythema migrans sera, but a frequent discrepancy between these two tests was noted as to positivity in individual sera. IgG Western blot was considered to be of less value for the diagnosis of current disease due to a high occurrence of positivity among controls.

Adolescent↗
PubMed1990

Modulation of the constitutive gene expression of the 55 kD tumor necrosis factor receptor in hematopoietic cells.

The expression of the 55 kD human tumor necrosis factor (TNF) receptor gene was investigated. By use of a 1.2 kb cDNA we demonstrated a constitutive expression of a single 2.3 kb transcript in cell lines and fresh blood cells. The TNF receptor gene expression was not affected by phorbol esters, dibutyryl cAMP (dbcAMP), interleukin-1 (IL-1), interferon-gamma (IFN-gamma) or by TNF, agents known to modulate functional TNF receptors. The phosphodiesterase inhibitor 3-isobutyl-1-methyl-xanthine (IBMX) showed a dose dependent inhibition of the TNF receptor gene expression. This inhibition is not mediated by cAMP, since neither dbcAMP nor forskolin had any effects on the expression of the 55 kD receptor gene. The results suggest that the effects of phorbol diesters, IL-1, IFN-gamma, TNF and dbcAMP previously observed on binding of TNF to cells are limited to posttranscriptional regulation of the 55 kD TNF receptor.

1-Methyl-3-isobutylxanthine↗
PubMed1990

Tumor necrosis factor-induced degranulation in adherent human neutrophils is dependent on CD11b/CD18-integrin-triggered oscillations of cytosolic free Ca2+.

We have recently been able to correlate closely the "spontaneous" oscillatory activity of cytosolic free Ca2+ in adherent human neutrophils with the ability of tumor necrosis factor (TNF) to induce secretion of granule proteins from these cells. In the present work we show with a single-cell technique that preincubation of human neutrophils with antibodies to CD18, the common beta chain of leukocyte adhesion proteins, inhibits TNF-induced secretion of lactoferrin in a time- and concentration-dependent manner. Similar effects of CD18 antibodies were found on chemotactic factor (fMet-Leu-Phe)- but not on phorbol 12-myristate 13-acetate-induced secretion, suggesting that cell-surface-receptor-mediated secretion is dependent on integrin-associated signals. Similarly, antibodies to CD11b (alpha chain of macrophage 1) also inhibited TNF- and fMet-Leu-Phe- but not phorbol 12-myristate 13-acetate-stimulated release of lactoferrin. Antibodies to CD11a (alpha chain of lymphocyte function-associated antigen 1) or CD11c (alpha chain of p150,95) had only a minimal effect on agonist-induced secretion. Data obtained in several laboratories, including our own, made us suspect that integrin interaction with the surface is responsible for the oscillatory activity of cytosolic free Ca2+ in adherent cells. Indeed, preincubation with antibodies to either CD18 or CD11b, but not to CD11c, inhibited the oscillations of cytosolic free Ca2+ in adherent neutrophils. This inhibitory effect was evident both as a reduction of the number of responding cells and as a reduction of the oscillatory activity in the cells. In conclusion, the oscillatory activity of cytosolic free Ca2+ in adherent neutrophils is mediated through the CD18/CD11b integrins. The generation of this Ca2+ signal may explain how adherence, by way of the integrins, changes the functional properties of the cell and enables TNF to induce secretion.

Antibodies, Monoclonal↗
PubMed1990

Molecular cloning and expression of human and rat tumor necrosis factor receptor chain (p60) and its soluble derivative, tumor necrosis factor-binding protein.

Tumor necrosis factor-alpha (TNF-alpha), a protein released by activated macrophages, is involved in a wide variety of human diseases including septic shock, cachexia, and chronic inflammation. TNF binding protein (TNF-BP), a glycoprotein with high affinity to TNF-alpha isolated from urine, acts as an inhibitor of TNF-alpha by competing with the cell-surface TNF receptor. We report here the partial amino acid sequencing of human TNF-BP as well as the isolation, sequence, and expression of cDNA clones encoding a human and rat TNF receptor. The calculated Mr of the mature human and rat TNF receptor chains is 47,526 and 48,072, respectively. The extracellular ligand binding domain represents the soluble TNF-BP which is released by proteolytic cleavage. TNF-BP contains 24 cysteine residues and three potential N-glycosylation sites and shows sequence homology to the extracellular portions of TNF-R p80 chain and nerve growth factor receptor. Transfection of the human TNF receptor cDNA into mammalian cells resulted in increased binding capacity for TNF-alpha and increased reactivity with a monoclonal antibody directed against the human TNF receptor chain p60. When a stop codon was introduced into the cDNA at the site corresponding to the carboxyl terminus of TNF-BP, transfected cells secreted a protein that reacted with antibodies raised against natural TNF-BP.

Amino Acid Sequence↗
PubMed1990

Nucleic acid association to human prostasomes.

Human prostasomes isolated from seminal plasma were subjected to phenol extraction and then to absorbance (A) measurements at 260 nm (A260) and 280 nm (A280). The A260/A280 ratio was about 2 for prostasome extract and lower for seminal plasma extract, indicative of the presence of nucleic acid. The ratio of nucleic acid to protein in prostasomes was about 1:100, and the ratio in seminal plasma was 1:1,000. Hence nucleic acid is enriched in prostasomes (compared to seminal plasma of 10). Treatment of prostasome samples with 2% sodium dodecyl sulfate resulted in an efficient dissociation of nucleic acid from prostasomes as demonstrated by electrophoresis. The association of nucleic acids of various sizes (range; 200 to 20,000 base pairs) to prostasome membranes was most probably genuine and not the result of contamination from spermatozoa, erythrocytes, leukocytes, or bacteria. The results of experiments employing nucleic acid-degrading enzymes favored the concept that double-stranded DNA but not RNA is present at the prostasome membrane surface.

DNA↗
PubMed1979

Effects of serum and cations on the selective release of granular proteins from human netrophils during phagocytosis.

The extracellular release from human neutrophils of the primary (azurophil) granule constituents, myeloperoxidase (MPO), chymotrypsin-like cationic protein (CCP), collagenase and lysozyme, and the secondary (specific) granule constituents, lactoferrin and lysozyme, was measured during ingestion of staphylococcus protein-A-IgG complexes. In buffer, lactoferrin release was consistently higher than that of the other protein. In serum, lactoferrin release increased concomitantly with ingestion, whereas the rate of lysozyme and especially of MPO release were stimulated to a higher degree than ingestion. Magnesium (0.5--2 mM) was more potent than calcium (0.5--2 mM) in promoting release but these cations worked synergistically. Zinc (0.5--4 mM) was found to be a potent and selective inhibitor of collagenase release. Manganese (0.25--4 mM), which inhibited the ingestion of SpA-IgG complexes, also inhibited release of CCP, collagenase, lysozyme and MPO, but actually stimulated lactoferrin release. The data suggests that lactoferrin and lysozyme may be confined to distinct granule populations or else released in a different fashion from the granules. When the effects on release of primary granule proteins are concerned it is suggested that the dissociation of binding of various agents to an anionic granule matrix may be affected differently by various cations.

Blood↗
PubMed1979

Blood eosinophils and eosinophil cationic protein after acute myocardial infarction or corticosteroid administration.

Measurements of eosinophil cationic protein in serum (S-ECP) have been made in patients with acute myocardial infarction. In spite of low numbers of blood eosinophils in the acute phase of the disease S-ECP levels fluctuated widely with often markedly raised levels. Peak levels of S-ECP were significantly correlated (P less than 0.001) to peak numbers of blood eosinophils, although the former usually occurred within the first 2-3 d of illness and the latter usually after the sixth day. Intravenous injection of 0.5 g methylprednisolone in healthy individuals reduced blood eosinophil counts for at least 24 h, but S-ECP levels remained within normal limits. These results suggest that ECP is released from eosinophils in vivo. The raised levels of S-ECP in patients with acute myocardial infarction are probably due to the active participation of eosinophils in the inflammatory process.

Acute Disease↗