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Biomedical subjects

A Olsson

Publications and source records attributed to A Olsson.

At least 91 records · Page 5Linked to original sources
PubMed1990

The specificity and cellular origin of phenylethanolamine N-methyltransferase (PNMT)-like immunoreactivity in psoriatic skin.

Phenylethanolamine N-methyltransferase (PNMT)-like immunoreactivity has been found in psoriatic skin and in this study, PNMT-like immunoreactivity was investigated in the involved and uninvolved skin of six patients with lichen planus and four patients with lichen simplex. No PNMT immunoreactivity was observed in these diseases. Studies were carried out using cultured fibroblasts from two patients with psoriasis from uninvolved and involved areas of skin and from two controls using antibodies to PNMT, as well as antibodies to the chemical messengers somatostatin, substance P, parathyroid hormone and peptide histidine isoleucine amide. No immunoreactivity to these substances was found, and fibroblasts are unlikely to be the cellular origin of the PNMT-like immunoreactivity as seen in psoriatic skin.

Adolescent↗
PubMed1990

CD8+ T lymphocyte subset in giant cell arteritis and related disorders.

Median percentage and number of circulating CD8+ T lymphocytes (suppressor/cytotoxic T lymphocytes) are markedly decreased in patients with giant cell arteritis (GCA). We assessed the diagnostic usefulness of CD8+ T cell values, in 108 patients who had a temporal artery biopsy during a 3 year period. Histologic evidence of GCA was found in 26 patients. Negative biopsy patients were divided into 2 groups, one with 49 patients and a probable GCA syndrome (polymyalgia rheumatica with a negative biopsy) and a group with non-GCA (33 patients). Median percentage and number of CD8+ T cells were significantly decreased with definite GCA (CD8+% 10.0, CD8+ cells 0.221 x 10(9)/l), and probable GCA syndrome (CD8+% 10.0, CD8+ cells 0.197 x 10(9)/l) compared with non-GCA (CD8+% 22.0, CD8+ cells 0.527 x 10(9)/l) and controls (CD8% 21, CD8+ cells 0.518 x 10(9)/l). Significantly low CD8+ T cell values were found in nearly 80% of patients with active untreated GCA or GCA syndrome and in 15% of patients with non-GCA. Positive predictive value of a significant low CD8+ T cell value is 85% while the likelihood of no GCA or GCA syndrome with normal CD8+ T cell values is 60%.

Biopsy↗
PubMed1989

Differential IgG-binding characteristics of staphylococcal protein A, streptococcal protein G, and a chimeric protein AG.

Various Gram-positive bacteria express different types of IgG-binding receptors, each of which displaying certain unique binding properties. To evaluate specificity and avidity aspects of the differential binding pattern, a set of competitive binding assays was employed, by using staphylococcal protein A (SPA), streptococcal protein G (SPG), and a chimeric protein AG. These receptors were analyzed, in a reciprocal fashion, for binding and inhibition of binding to a selected panel of polyclonal and monoclonal Ig. Results of the study reveal that a majority of the determinants on human and bovine IgG, recognized by SPA and SPG, are either coextensive or closely overlapping. Accordingly, a minor portion of the determinants appear to be unique in the sense that a particular determinant(s) is selectively identified by one of the two receptors. Binding assays involving purified Fc fragments from human IgG, suggest that SPG shows exclusive specificity for an Fab region determinant(s) not recognized by SPA, whereas the Fc determinants for SPA and SPG are identical or overlapping. Furthermore, one of the IgG subclasses of bovine origin appears to be seen by the SPG receptor only. The competition study also demonstrates that the novel chimeric protein AG receptor shows higher or equal avidity for variants of human IgG molecules compared to the best of its parental constituents. It can thus be deduced that chimeric receptors might be useful as optimized tools for immunologic applications.

Animals↗
PubMed1988

The 5' flanking region of the gene for the Epstein-Barr virus-encoded nuclear antigen 2 contains a cell type specific cis-acting regulatory element that activates transcription in transfected B-cells.

We have recently identified the promoter that positions the initiation (cap) site for RNA encoding the Epstein-Barr virus (EBV) determined nuclear antigen 2 (EBNA2) in transfected COS-1 cells. The cells were transfected with recombinant vectors that contained the BamHI WYH region of the EBV genome. In order to delineate regulatory DNA sequences required for the expression of EBNA2 the 5' flanking region of the gene was linked to reporter genes in expression vectors and transfected into EBV genome-negative lymphoid DG75 cells. We demonstrate that several cis-acting elements contribute to a transcriptional enhancer activity found in the region between nucleotides-553 and -86 relative to the cap site. The enhancer was active in lymphoid DG75 cells but not in HeLa cells and stimulated transcription also from the heterologous thymidine kinase (TK) and beta-globin promoters. Nuclear extracts of lymphoid cells contained protein factors that bound to the enhancer. The in vitro introduction of a mutation in the enhancer sequence that substantially reduced the transcription stimulatory activity concurrently blocked the binding of one of the factors.

Animals↗
PubMed1988

Solid phase DNA sequencing using the biotin-avidin system.

A novel method for solid-phase DNA sequencing is described. A plasmid vector, pRIT27, has been designed to allow directional immobilization of double stranded plasmid to avidin agarose. The strategy involves enzymatic incorporation of 11-bio-dUTP into the plasmid and strand specific elution using alkali. The immobilized single stranded DNA is used as template for sequencing reactions and the resulting labelled oligonucleotides are eluted by alkali. The affinity gel containing the immobilized template is consecutively used for the four different dideoxy-nucleotide reactions. The solid-phase technique can be used for both primer specific or extension specific labelling. The possibility to use the system in automated DNA sequencing is discussed.

Autoanalysis↗
PubMed1988

Chimeric IgG-binding receptors engineered from staphylococcal protein A and streptococcal protein G.

Chimeric Fc receptors, consisting of the IgG-binding domains of both staphylococcal protein A and streptococcal protein G, were constructed. An efficient bacterial expression system was used to produce the recombinant proteins, which vary in size and number of IgG-binding domains. The purified receptors were analyzed by immunodiffusion and a competitive enzyme-linked immunosorbent assay to establish the relative binding strength to various polyclonal and monoclonal immunoglobulins from different species. The results demonstrate that protein A and protein G have complementary binding patterns and that the chimeric receptors retain the binding capacities of both the parental constituents. This suggests that these novel chimeric receptors might be versatile reagents for immunochemical assays.

Animals↗
PubMed1987

Structure and evolution of the repetitive gene encoding streptococcal protein G.

The complete sequence of the structural gene encoding the immunoglobulin G binding protein from Streptococcus G148 has been determined, as well as its 5' and 3' flanking sequences. The sequence reveals an open reading frame encoding a putative preprotein with a relative molecular mass of 63294. N-Terminal sequencing of the mature protein, spontaneously released from streptococcal cells, demonstrates that the signal peptide consists of 33 amino acids. The DNA sequence reveals extensive internal homologies similar to other cell-wall-bound receptors from gram-positive bacteria. Comparisons with a related gene previously isolated from another strain of streptococci revealed large differences in size, due to variations in the number of internal repeats. The structure of the gene suggests an evolution through multiple duplications.

Amino Acid Sequence↗
PubMed1987

Expression of human insulin-like growth factor I in bacteria: use of optimized gene fusion vectors to facilitate protein purification.

Several fusions between the gene for human insulin-like growth factor I (IGF-I) and the genes for different IgG-binding fragments of staphylococcal protein A were assembled and compared regarding expression, secretion, and purification of the peptide hormone. After IgG affinity purification of the fusion proteins from the growth medium of Staphylococcus aureus or Escherichia coli, native IGF-I was released by cleavage of an Asn-Gly peptide bond with hydroxylamine. An optimized expression system based on a modified synthetic IgG-binding domain (z), resistant to hydroxylamine, gave the highest yield of fusion protein. After cleavage, the hormone could be separated from the IgG-binding moiety and from noncleaved fusion protein by a second passage through the IgG affinity column. The biological activity and the purity of the IGF-I obtained were confirmed by a radioreceptor assay, N-terminal sequence analysis, polyacrylamide gel electrophoresis, isoelectric focusing, and high-performance liquid chromatography.

Cloning, Molecular↗
PubMed1987

Phenylethanolamine N-methyltransferase-like immunoreactivity in psoriasis. An immunohistochemical study on catecholamine synthesizing enzymes and neuropeptides of the skin.

Immunoreactivity for phenylethanolamine N-methyltransferase (PNMT), the enzyme involved in the conversion of norepinephrine to epinephrine, was present in the basal epidermis and upper dermis in 16 patients with psoriasis. The amount of immunoreactivity was increased tenfold in involved compared to uninvolved skin as characterized by computer-assisted image analysis. In skin from healthy volunteers no immunoreactivity could be found. In our subjects, no immunoreactivity was observed for the other catecholamine synthesizing enzymes (tyrosine hydroxylase; dopa-decarboxylase; dopamine-beta-hydroxylase), apart from single tyrosine hydroxylase positive adrenergic vascular nerves. Furthermore, in psoriasis, the immunoreactivity pattern of the peptides somatostatin, substance P, vasoactive intestinal polypeptide and bombesin was in agreement with skin from healthy volunteers.

Adult↗
PubMed1986

Structure of the IgG-binding regions of streptococcal protein G.

The gene encoding the IgG-binding protein G from Streptococcus G148 was isolated by molecular cloning. A subclone containing a 1.5-kb insert gave a functional product in Escherichia coli. Protein analysis of affinity-purified polypeptides revealed two gene products, both smaller than protein G spontaneously released from streptococci, but with identical IgG-binding properties. The complete nucleotide sequence of the insert revealed a repeated structure probably evolved through duplications of fragments of different sizes. The deduced amino acid sequence revealed an open reading frame extending throughout the insert, terminating in a TAA stop codon. Analysis of the two gene products by N-terminal amino acid determination suggests that two different TTG codons are recognized in E. coli for initiation of translation to yield the two products. Based on these results several truncated gene constructions were expressed and analysed. The results suggest that the C-terminal part of streptococcal protein G consists of three IgG-binding domains followed by a region which anchors the protein to the cell surface. Structural and functional comparisons with streptococcal M protein and staphylococcal protein A have been made.

Amino Acid Sequence↗
PubMed1986

Sequencing and heterologous expression of the gene encoding penicillin V amidase from Bacillus sphaericus.

The Bacillus sphaericus gene encoding penicillin V amidase, which catalyzes the hydrolysis of penicillin V, has been characterized. The entire nucleotide sequence of the coding region, as well as 5'- and 3'-flanking regions, was determined using an improved sequencing strategy. The deduced amino acid sequence suggests a protein consisting of 338 residues with an Mr of 37,500. The ATG initiator codon is preceded by a putative ribosome-binding site, typical for genes of Gram-positive origin. High expression of the gene was obtained in Escherichia coli using an inducible promoter, showing that the gene product is stable in this heterologous host.

Amidohydrolases↗