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Biomedical subjects

B Nilsson

Publications and source records attributed to B Nilsson.

At least 289 records · Page 16Linked to original sources
PubMed1991

Chlamydia trachomatis and Chlamydia pneumoniae bind specifically to phosphatidylethanolamine in HeLa cells and to GalNAc beta 1-4Gal beta 1-4GLC sequences-found in asialo-GM1 and asial-GM2.

To examine the possible role of lipids as adhesion receptors for infection, Chlamydia trachomatis and Chlamydia pneumoniae were labeled with 125I and layered on thin-layer chromatograms (tlc) of separated lipids isolated from target cells, and bound bacteria were detected by autoradiography. Elementary bodies from both species bound specifically and with high affinity to one lipid in HeLa 229 cells. Purification of this receptor by column chromatography on DEAE Sepharose followed by continuous preparative tlc, and structural analysis by 500-MHz 1H-NMR spectroscopy and fast atom bombardment mass spectrometry confirmed the HeLa cell chlamydial receptor to be phosphatidylethanolamine (PE). The chlamydiae also bound strongly to purified asialo-GM1 and asialo-GM2, but not to other neutral or acidic lipids tested. The relative binding of chlamydiae to human PE and asialo-GM1 was modified in the presence divalent cations, suggesting that chlamydiae have two interrelated receptor binding sites.

Bacterial Adhesion↗
PubMed1991

Secretion incompetence of bovine pancreatic trypsin inhibitor expressed in Escherichia coli.

There is increasing evidence that protein folding and protein export are competing processes in prokaryotic cells. Virtually all secretion studies reported to date, however, have employed proteins that are relatively uncharacterized in terms of their folding behavior and three-dimensional structure. In contrast, the structural and biochemical parameters governing the folding of bovine pancreatic trypsin inhibitor (BPTI) and several of its mutants have been studied intensively. We therefore undertook a study of the secretion behavior in Escherichia coli of recombinant BPTI and its mutants. Wild-type BPTI and two well-characterized folding mutants (C14A, C38A)BPTI and (C30A, C51A)BPTI (missing the 14-38 and 30-51 disulfide bonds, respectively), were investigated by analyzing their expression fused to an E. coli signal sequence or to two synthetic IgG-binding domains of staphylococcal protein A. Both disulfide mutants are destabilized relative to wild-type BPTI and exhibit markedly altered folding kinetics: one (C14A, C38A) folds more slowly than wild-type BPTI and the other (C30A, C51A) unfolds more rapidly. Both mutants were observed to be exported 3-10 times more efficiently than the wild-type molecule. Moreover, the levels of unprocessed preprotein in the cytoplasm were severalfold higher for the wild-type fusion than for the fusion to the two folding mutants. Intracellular degradation of the BPTI moiety was also observed. These results are consistent with traffic of intracellular BPTI preproteins on at least three routes along the secretory pathway: (a) facile secretion of unfolded material, (b) intracellular folding leading to secretion blockage, and (c) degradation followed by export of truncated molecules. A novel feature of these findings is the implication that disulfide bonds can form in the bacterial cytoplasm and lead to secretion incompetence.

Amino Acid Sequence↗
PubMed1991

Structural analysis of a glycosylphosphatidylinositol glycolipid of Leishmania donovani.

A glycosylphosphatidylinositol (GPI) glycolipid antigen recognized by sera from patients with visceral leishmaniasis was isolated from Leishmania donovani promastigotes. The carbohydrate moiety was cleaved from the lipid part by digestion with specific phosphatidylinositol phospholipase C. After separation, structural analysis was carried out on the phosphorylated inositol oligosaccharide and the alkylacyl glycerol. The following major structures were found: [formula: see text] The presence of the conserved sequence Man alpha 1-2Man alpha 1-6Man alpha 1-4GlcN-PI of glycosyl phosphatidylinositol protein anchors in this antigen may be consistent with a precursor role of Leishmania glycosyl phosphatidylinositol anchored proteins for this glycolipid.

Animals↗
PubMed1991

Defective Fc receptor-mediated clearance in patients with primary biliary cirrhosis.

Fc receptor-mediated clearance of immunoglobulin G-coated autologous erythrocytes was studied in patients with primary biliary cirrhosis (n = 14), alcoholic liver cirrhosis (n = 5) and healthy reference individuals (n = 14). The mean half-life of the sensitized erythrocytes was significantly prolonged in patients with primary biliary cirrhosis (85 +/- 25 minutes; P less than 0.001) compared with the corresponding value in patients with alcoholic cirrhosis (16 +/- 2 minutes) and healthy reference individuals (20 +/- 5 minutes), respectively. No correlation between clearance rate and age, liver histopathology, or serum levels of bilirubin, aminotransferases, immunoglobulin G, immunoglobulin A, and Clq binding or C3-containing immune complexes was found. The results presented here indicate a profound disturbance of Fc receptor-mediated immune clearance function in patients with primary biliary cirrhosis.

Antigen-Antibody Complex↗