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Biomedical subjects

F Poulsen

Publications and source records attributed to F Poulsen.

14 recordsLinked to original sources
PubMed2000

Effects of topiramate on kainate- and domoate-activated [14C]guanidinium ion flux through GluR6 channels in transfected BHK cells using Cytostar-T scintillating microplates.

PURPOSE: This study was undertaken to test the hypothesis that topiramate (TPM) exerts a negative modulatory effect on some types of alpha-amino-3-hydroxy-5-methylisoxazole-4-proprionic acid (AMPA)/kainate receptors by binding to the site at which protein kinase A (PKA) phosphorylates the receptor-channel complex. METHODS: The effect of TPM on kainate- or domoate-induced [14C]guanidinium ion flux through iGluR6 channels expressed in baby hamster kidney (BHK) cells was evaluated. Because the hypothesis predicts that TPM will bind only in the dephosphorylated state, a variety of experimental conditions were used to either promote or impede the phosphorylation of the receptor-channel complex. These included the use of dibutyryl cyclic adenosine monophosphate (cAMP) and forskolin to activate PKA, H-9 and H-89 to inhibit PKA, and okadaic acid to inhibit protein phosphatases. RESULTS: Kainate (1 microM) induced a gradual accumulation of [14C]guanidinium into the cells that plateaued approximately 30 min after initiation of the reaction, whereas domoate (0.1 microM) caused a rapid accumulation into the cells that peaked within 5 min; thereafter, the amount of [14C]guanidinium in the cells declined gradually. Topiramate, at 0.1 and 100 microM, did not significantly affect the [14C]guanidinium accumulation under any of the experimental conditions used. CONCLUSIONS: The results of this study are not consistent with the hypothesis tested. However, the results must be interpreted cautiously because iGluR6 receptors expressed in the BHK cells and the functional state of proteins that regulate AMPA/receptors (e.g., PSD-95) may not be sufficiently similar to the receptors and functional state in neurons to serve as a true test of the hypothesis.

Animals↗
PubMed1997

The expression of an abscisic acid-responsive glycine-rich protein coincides with the level of seed dormancy in Fagus sylvatica.

By differential screening of a cDNA library constructed from poly (A+) RNA of ABA-treated seeds of Fagus sylvatica L., we have isolated an ABA-responsive clone that is present in dormant seeds and under conditions that maintain dormancy, but it tends to disappear under conditions breaking seed dormancy. A search of the sequence data bases showed that the clone codes for a Glycine-Rich Protein and has sequence similarity to RNA-binding proteins. The clone, which exibits the characteristics of lea-genes, is up-regulated by ABA and down-regulated by GA3. Paclobutrazol abolishes the effect of GA3, which is restored upon addition of GA3. The possible relationship of this Glycine-Rich Protein to seed dormancy in F. sylvatica is discussed.

Abscisic Acid↗
PubMed1996

Immunological aspects of recombinant factor VIIa (rFVIIa) in clinical use.

Patients, receiving rFVIIa for treatment of bleeding disorders, have been followed for specific antibody formation. No antibodies against FVII were demonstrated in 170 patients, with hemophilia, or with acquired inhibitors to clotting factors. Of 6 FVII-deficient patients, one overdosed patient developed antibodies to human FVII. There was no indication of de novo formation of antibodies to potential contaminating foreign protein, which could be correlated to the rFVIIa treatment. Except for the FVII-deficient population, which may represent a risk group, rFVIIa appears to be immunologically safe for use in patient groups with bleeding disorders, including hemophilia A and B patients.

Animals↗
PubMed1993

Enzyme immunoassay for intact human insulin in serum or plasma.

We describe an enzyme-linked two-site immunoassay for quantitation of intact insulin in human serum and plasma. The method uses two murine monoclonal antibodies that bind to two different epitopes on the insulin molecule. The immunoassay is specific. Human proinsulin is not bound by the antibodies, and the binding of partially processed proinsulin intermediates is believed to be of minor clinical importance. The relative response of human, bovine, and porcine insulin is 1, 1, and 3, respectively. The assay is sensitive (detection limit 5 pmol/L), accurate (101% recovery with 50 pmol/L insulin added to samples, 95% with 100 pmol/L, and 89% with 300 pmol/L), and fast (results within 3 h), and has a high analytical capacity (done in microtiter plates). The working assay range selected is 5-600 pmol/L, corresponding to a clinically useful range. Because of its specificity, this two-site immunoassay gives results that are lower than those obtained by using a competitive radioimmunoassay, both in normal individuals and in non-insulin-dependent diabetics.

Adult↗
PubMed1983

The nature of an iso-antigen of the human sperm membrane.

An iso-antigen has been isolated from tritium-labelled human spermatozoa by detergent solubilization, lectin affinity chromatography and indirect immunoprecipitation using human iso-antisera. Isolated material was characterized by SDS-polyacrylamide gel electrophoresis. With these iso-antisera it was possible to isolate material showing the same electrophoresis pattern, i.e. four polypeptide chains, one of molecular weight 41000, two around 77000 and one about 120000. The same pattern was obtained with an auto-antiserum. Sequential indirect immunoprecipitation showed that iso- and auto-antisera can react against the same antigen.

Antibody Specificity↗
PubMed1983

An improved method for isolation of tritium-labelled auto-antigen I of the human sperm membrane.

The isolation of tritium-labelled auto-antigen I of the human sperm membrane can be improved by including a gel chromatography step on a Sephadex G-200 column in the isolation procedure. The antigen was isolated from tritium-labelled spermatozoa by detergent solubilization, lectin affinity chromatography, gel chromatography and indirect immunoprecipitation. The gel chromatography removed the majority of material which binds non-specifically in the indirect immunoprecipitation and which had complicated the electrophoretic analysis of the isolated antigen. The auto-antigen was found to have a molecular weight greater than 150,000 and to exhibit an electrophoresis pattern of six polypeptide chains with molecular weights of 21,000, 32,000, 41,000, two around 77,000, and 120,000.

Antigens↗
PubMed1981

Analysis of auto-antigens in the human sperm membrane by a F(ab')2 blocking system.

F(ab')2 preparations from human sperm-agglutinating and -immobilizing sera react with the sperm-membrane antigens without exerting immobilizing activity. Therefore, human spermatozoa, treated with such F(ab')2 fragments--and consequently with certain antigens blocked by the fragments--could be used in immobilization experiments with sperm-immobilizing sera. If a serum revealed a significantly reduced immobilizing activity on such F(ab')2-covered spermatozoa, compared with the effect on spermatozoa treated with F(ab')2 fragments from normal human serum, this was taken as evidence that the F(ab')2 fragments and the serum antibodies were directed against the same antigen or closely associated antigenic determinants. By cross-testing a panel of sera against the corresponding F(ab')2 preparations two main patterns of reactivity were observed indicating that at least two different auto- and iso-antigens (antigenic determinants) can be involved in sperm immobilization. Rather unexpectedly the reactivities in the F(ab')2-blocking system were not related to the different modes of agglutination observed with the sera (head-to-head, tail-to-tail or mixed agglutination).

Antigens↗
PubMed1981

Identification of auto-antigens of the human sperm membrane.

Glycoproteins of human sperm membranes were labelled by a galactose oxidase-tritiated-sodium borohydride technique and detergent solubilized. A glycoprotein-enriched-fraction was obtained by lectin affinity chromatography. Subsequently, antigens in this fraction were isolated from the glycoprotein mixture by indirect immunoprecipitation and analysed in SDS-polyacrylamide gel electrophoresis. With some human sera with sperm agglutinating and immobilizing auto-antibodies at least three polypeptide chains were isolated, one with a molecular weight of about 41,000 and two with molecular weights of about 77,000. Other sera with equally strong agglutination and immobilization did not reveal any peaks in SDS-gel electrophoresis. Absorption studies using sequential indirect immunoprecipitation showed that the former group of sera independently of their mode of agglutination reacted with the same antigen(s).

Antigens↗
PubMed1980

Bromelin for liquefaction of cervical mucus in sperm antibody testing: its effect on spermagglutinating immunoglobulin G.

Incubation of cervical mucus with the proteolytic enzyme bromelin is known to result in complete liquefaction of the gel. This effect has been used in the detection spermagglutinating antibodies in cervical mucus. However, the well-known papain-like effect of bromelin on human immunoglobulin G (IgG) might be expected to lead to an underestimation of the sperm antibody activity in cervical mucus. This possibility was investigated by studying the effect of bromelin on known amounts of purified IgG from four spermagglutinating sera. Serologic testing of bromelin-treated samples of cervical mucus mixed with purified IgG revealed no effect on spermagglutinin titers, whereas a significant effect was observed on purified IgG alone. Inert proteins in cervical mucus seem to protect the antibodies against degradation, apparently by substrate competition. Liquefaction of cervical mucus by bromelin seems to be a better basis for the assessment of the sperm antibody content of the mucus than extraction procedures, which have been shown to give a deficient yield.

Antibodies↗
PubMed1980

A simple method for the production of F(ab')2 preparations by pepsin digestion of total serum protein.

An easy and rapid method for producing F(ab')2 fragments by pepsin treatment of total serum protein is described. No further purification of the hydrolysate was used. Most serum proteins were degraded to small peptides which were removed by dialysis, the preparations thus being relatively rich in F(ab')2 fragments. The degree of hydrolysis was determined by means of an antiserum against the part of the gamma-chain which is degraded by pepsin. Under optimal conditions for hydrolysis, unsplit IgG could not be detected by double immunodiffusion. Using sperm-agglutinating and immobilizing sera, the F(ab')2 preparations could be characterized functionally. After hydrolysis the agglutinating activity was relatively unchanged, whereas the immobilizing activity had vanished.

Blood Proteins↗
PubMed1978

Reactivity of F(ab)2 fragments of sperm antibodies in agglutination, immobilization and immunofluorescence tests.

The reactivity of F(ab)2 fragments of sperm antibodies was studied in agglutination, immobilization and immunofluorescence tests. Pepsin digestion of full serum was an easy and effective procedure for preparing F(ab)2 fragments. Compared to the reactions with serum, F(ab)2 preparations revealed only a moderate decrease in agglutination titres but a complete loss of immobilizing activity. In immunofluorescence tests, nonspecific background staining was strongly reduced by using F(ab)2 fragments, thereby offering a more reliable basis for the reading of reactions. Even though the titres obtained with serum and F(ab)2 preparations did not differ essentially, it is suggested that the use of F(ab)2 fragments in IF-tests on spermatozoa may help to provide a higher degree of reproducibility.

Antibodies↗
PubMedDate not supplied

The function of acyl-CoA-binding protein (ACBP)/diazepam binding inhibitor (DBI).

Acyl-CoA-binding protein has been isolated independently by five different groups based on its ability to (1) displace diazepam from the GABAA receptor, (2) affect cell growth, (3) induce medium-chain acyl-CoA-ester synthesis, (4) stimulate steroid hormone synthesis, and (5) affect glucose-induced insulin secretion. In this survey evidence is presented to show that ACBP is able to act as an intracellular acyl-CoA transporter and acyl-CoA pool former. The rat ACBP genomic gene consists of 4 exons and is actively expressed in all tissues tested with highest concentration being found in liver. ACBP consists of 86 amino acid residues and contains 4 alpha-helices which are folded into a boomerang type of structure with alpha-helices 1, 2 and 4 in the one arm and alpha-helix 3 and an open loop in the other arm of the boomerang. ACBP is able to stimulate mitochondrial acyl-CoA synthetase by removing acyl-CoA esters from the enzyme. ACBP is also able to desorb acyl-CoA esters from immobilized membranes and transport and deliver these for mitochondrial beta-oxidation. ACBP efficiently protects acetyl-CoA carboxylase and the mitochondrial ADP/ATP translocase against acyl-CoA inhibition. Finally, ACBP is shown to be able to act as an intracellular acyl-CoA pool former by overexpression in yeast. The possible role of ACBP in lipid metabolism is discussed.

Acyl Coenzyme A↗