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Biomedical subjects

S Fredriksson

Publications and source records attributed to S Fredriksson.

9 recordsLinked to original sources
PubMed1999

Inversion of in situ synthesized oligonucleotides: improved reagents for hybridization and primer extension in DNA microarrays.

Oligonucleotides synthesized in array format suffer from contamination by truncated species. We have developed a method to invert DNA molecules in situ after completed synthesis. Reactive functions at the 5'-ends of the oligonucleotides are permitted to react with functions on the support before the 3'-ends are released, in effect reversing the orientation of full-length oligonucleotides, while any 5'-truncated molecules are lost. This strategy serves both to purify in situ synthesized reagents and to reorient the oligonucleotides, causing them to expose free 3'-hydroxyls. In situ inverted oligonucleotides can be used in assays based on DNA polymerase-assisted extension of immobilized primers, and we demonstrate their utility in minisequencing and in pyrosequencing.

Base Sequence↗
PubMed1994

Imaging human erythrocyte spectrin with atomic force microscopy.

Isolated spectrin covalently attached to a surface in a liquid environment as well as dried on mica has been studied with a contact-mode atomic force microscope. Both pyramidal and conical-type cantilever tip facets were used in the AFM. Our images show structures and give dimensions that correlate well with previous structural studies using transmission electron microscopy.

Erythrocyte Membrane↗
PubMed1993

Optic neuritis and multiple sclerosis: anti-MBP and anti-MBP peptide antibody-secreting cells are accumulated in CSF.

Monosymptomatic unilateral optic neuritis (ON) is a common first manifestation of multiple sclerosis (MS) in which increased numbers of autoimmune T and B cells, recognizing different myelin autoantigens including myelin basic protein (MBP) and its peptides, have been implicated in a hypothetical immunopathogenesis. Using an immunospot assay to detect specific antibodies secreted by individual cells, we analyzed the B-cell repertoire to MBP and its amino acid residues 1-20, 63-88, 110-128, and 148-165 in blood and CSF from patients with ON and MS, and from controls. There were cells secreting IgG antibodies to MBP and the four peptides in blood at mean numbers of 0.9 to 4.6 per 10(5) mononuclear cells, without differences between the three patient groups. Mostly, more than 100-fold more B cells with these specificites per 10(5) cells were found in CSF from the patients with ON and MS, without differences between these two groups but with many fewer in CSF from controls. None of the four included MBP peptides represented an immunodominant B-cell epitope in either ON or MS, and the B-cell response was not more restricted in ON than in MS. The autonomy of the autoimmune B-cell response in CSF was further supported by the pronounced asynchrony of the repertoire to the four MBP peptides in CSF compared with blood in individual patients. The large numbers of MBP- and MBP peptide-reactive B cells in CSF in early MS, as manifested by ON, could play a major role in the immunopathogenesis and perpetuation of MS. Alternatively, they could represent myelin breakdown or restoration.

Adult↗
PubMed1989

Leukocyte types in cerebrospinal fluid and peripheral blood enumerated immunoenzymatically in aseptic meningitis and the Guillain-Barré syndrome.

To study celltype distribution simultaneously in peripheral blood (PB) and cerebrospinal fluid (CSF) from patients with aseptic meningitis (AM) (n = 14) and Guillain-Barré syndrome (GBS) (n = 9) we used an immunoenzymatic method that enabled the use of several monoclonal antibodies, also in CSF samples with normal cellcounts. In both patient groups a different cell-distribution in CSF compared to PB was found with regard to pan T cells (CD5+/anti-Leu1+), T cell subpopulations (CD4+/anti-Leu3+, CD8+/anti-Leu2+), B cells (OKB2+, OKB7+), monocytes/macrophages (CD11+/OKM1+) and HLA/DR expressing cells, whereas the distribution of HLA/DC+ cells was similar in CSF and PB. Thus, the CSF cell distribution does not reflect the distribution in PB. The proportion of T cells was higher and the proportion of B-cells was lower in CSF than in PB in both patient groups, which is a finding similar to that in patients with multiple sclerosis. The OKT9 marker, labelling proliferating cells expressing the transferrin receptor, was not useful as marker of local proliferation.

Adult↗
PubMed1978

Isoelectric focusing of the phosphoprotein of rat-incisor dentin in ampholine and acid pH gradients. Evidence for carrier ampholyte-protein complexes.

Rat-incisor phosphoprotein (RIP) has been subjected to isoelectric focusing at 4 degrees in (a) an Ampholine pH gradient of 2.5-4 and (b) an acid pH gradient created by electrolysis of a system of acids and acidic ampholytes and covering the pH range 0.5-3.5. In the Ampholine gradient, the RIP unexpectedly formed several adjacent and strongly opalescent bands in the pH range 2.5-3.1. These bands, which migrated slowly toward the anode on prolonged focusing, are interpreted as being the result of an interaction between the amino groups of the Ampholine and the numerous phosphate groups of the protein. In the acid pH gradient, the RIP focused into one narrow zone corresponding to an isoelectric pH of 1.1 at 4 degrees. This value is consistent with the amino-acid composition and the phosphate content of the protein,

Animals↗
PubMed1975

Scanning isoelectric focusing in small density-gradient columns. IV. The use of deuterium oxide for preparing the density gradient and its effects on isoelectric points of proteins.

The use of deuterium oxide as a substitute for sucrose in preparing density gradients for small isoelectrofocusing columns has been investigated. A density gradient was created directly in a 1.5-ml column by free inter-diffusion of three deuterium oxide solutions for 3 min. The resulting deuterium oxide concentration course (as shown by measurement of the refractive-index gradient) had a very high degree of linearity. Test runs with beta-lactoglobulin and sperm-whale myoglobin showed that the strength and stability of the deuterium oxide density gradient should normally be sufficient for stabilization of protein zones against convection during isoelectric focusing. The isoelectric points of beta-lactoglobulins A and B were found to increase as the concentration ratio of deuterium oxide to water at focusing level increased. Within the limits of experimental error, the pI shift corresponding to a given change in solvent composition was equal for both components. These findings are accounted for in terms of the deuterium isotope effect on the dissociation constants of protolytic groups and the shift in the asymmetry potential of the glass electrode in deuterium oxide as compared with water. The spontaneous reduction of sperm-whale metmyoglobin to ferrous myoglobin, which occurs on prolonged isoelectric focusing, is discussed, as are the benefits and drawbacks of deuterium oxide as a density-gradient solute.

Animals↗