Biomedical subjects

M Byström

Publications and source records attributed to M Byström.

6 recordsLinked to original sources

PubMed2000

Differences in surface-exposed antigen expression between Helicobacter pylori strains isolated from duodenal ulcer patients and from asymptomatic subjects.

We have analyzed possible qualitative and quantitative differences in antigen expression between Helicobacter pylori strains isolated from the antrum and different locations in the duodenum of 21 duodenal ulcer (DU) patients and 20 asymptomatic subjects (AS) by enzyme-linked immunosorbent assay (ELISA) and inhibition ELISA. Almost all antral and duodenal strains grown in vitro expressed the N-acetyl-neuroaminyllactose-binding hemagglutinin, flagellins (subunits FlaA and FlaB), urease, a 26-kDa protein, and a neutrophil-activating protein. In 75% of both the DU patients and the AS, antral H. pylori strains expressed either the blood group antigen Lewis y (Le(y)) alone or together with the Le(x) antigen. However, duodenal H. pylori strains of DU patients expressed Le(y) antigen more frequently than corresponding strains of AS (P < 0.05). Presence of Le(y) on H. pylori was related to the degree of active duodenitis (P < 0.05). Duodenal H. pylori strains isolated from AS were significantly more often Lewis nontypeable than duodenal strains of DU patients (P < 0.01). Presence of H. pylori blood group antigen-binding adhesin (BabA) was significantly higher on both antral and duodenal strains isolated from DU patients than on corresponding strains isolated from AS (P < 0.05). BabA-positive duodenal H. pylori strains isolated from DU patients were associated with active duodenitis more frequently than corresponding strains isolated from AS (P < 0.01). Infection with H. pylori strains positive for Le(y) and BabA in the duodenum is associated with development of duodenal ulcer formation.

ABO Blood-Group System↗

PubMed1998

Characterization and molecular cloning of vascular neuropeptide Y receptor subtypes in pig and dog.

Cloning with subsequent in vitro and in vivo characterization of vascular neuropeptide Y (NPY) receptor subtypes in porcine and canine peripheral tissues was performed. RT-PCR with Y1 and Y2 receptor-specific primers, indicated expression of Y1 receptors in both kidney and spleen of dog and pig, and expression of Y2 receptors in pig spleen. In pig kidney, expression of Y1 receptor mRNA was located to intrarenal arteries, as demonstrated with in situ hybridization using human probes. The cloned and sequenced canine Y1, porcine Y1 and Y2 receptors revealed high homologies to previously characterized mammalian NPY receptors. Membrane and autoradiographic receptor binding studies showed specific high-affinity binding sites for the purported Y1-selective radioligands 125I-[Leu31Pro34]peptide YY (PYY) and 3H-BIBP 3226 in dog spleen, and for the putative Y2-selective 125I-PYY(3-36) in dog and pig spleen. In the pig in vivo, [Leu31Pro34]PYY, administered i.v., evoked vasoconstriction in spleen and kidney, actions that were potently inhibited by the non-peptide Y receptor antagonist SR 120107A. In contrast, PYY(3-36) evoked vasoconstriction only in spleen and this effect was not influenced by SR 120107A. NPY evoked renal and splenic vasoconstriction in the dog in vivo, vascular responses that were inhibited by both BIBP 3226 and SR 120107A. Furthermore, the Y1 receptor agonist [Leu31Pro34]NPY also caused vasoconstriction in dog kidney and spleen, whereas the putative Y2 agonist N-acetyl[Leu28Leu31]NPY(24-36) evoked no such vascular responses. It is concluded that the pig spleen is likely to contain Y1 and Y2 receptors, both involved in splenic vasoconstriction. In contrast, the Y1 receptor seems to be the sole vascular NPY receptor subtype in pig kidney. Moreover, Y1 receptors predominate in dog spleen and kidney. Furthermore, the cloned canine Y1 receptor and the porcine Y1 and Y2 receptors show great homologies to, and possess ligand requirement profiles in accordance with, the human forms.

Amino Acid Sequence↗

PubMed1997

Expression and characterization of phosphorylated recombinant human beta-casein in Escherichia coli.

Specific serine and threonine residues of recombinant human beta-casein produced in Escherichia coli were shown to be phosphorylated in vivo when human casein kinase II was coexpressed in the same plasmid. All of the phosphorylated forms found in the native protein were also detected in the recombinant protein. The phosphorylation of recombinant human beta-casein was confirmed by immunoblots, fast protein liquid chromatography, urea-polyacrylamide gel electrophoresis, SDS-polyacrylamide gel electrophoresis, and liquid chromatography-mass spectrometry. The results indicate that the substrate specificity of casein kinase II in vivo was unaffected in its recombinant form. This is the first demonstration of in vivo phosphorylation of specific residues of a multiphosphorylated protein produced in E. coli with a single plasmid.

Casein Kinase II↗

PubMed1996

Characterisation of the complex of plasminogen activator inhibitor type 1 with tissue-type plasminogen activator by mass spectrometry and size-exclusion chromatography.

Glycosylated human plasminogen activator inhibitor type 1 (PAI-1), produced in Chinese hamster ovary (CHO) cells, showed a variety of compounds with different molecular weights when subjected to electrospray mass spectrometry (ES-MS), owing to the heterogeneity of the carbohydrate chains. However, non-glycosylated human PAI-1, produced in E. coli, gave rise to a prominent species with a molecular weight of 42,774, consistent with the amino-acid sequence. A non-glycosylated mutant of the proteinase domain (B-chain) of tissue-type plasminogen activator (tPA) produced in C 127 cells, had a molecular weight of 28,168. Full-length, glycosylated, tPA showed a large heterogeneity in molecular mass. For a mass study, a tPA-PAI-1 complex was formed, composed of non-glycosylated PAI-1 and non-glycosylated B-chain. This complex was remarkably stable at room temperature in buffer with a neutral pH. The mass spectrum of the complex provided two main species, a peptide with a mass of 3803 and a dominating species of 67,133. These masses are consistent with a complex where PAI-1 is cleaved at the P1-P1' position. A trace of a species with a molecular mass of 70,942 was also found, corresponding to the complete, non-dissociated complex with PAI-1. Separation of the cleaved peptide, corresponding to the hydrophobic C-terminal 33 amino-acid residues of PAI-1, from the complex, was achieved by size-exclusion chromatography in the presence of 30% acetonitrile. Thus, in the complex between tPA and PAI-1, the proteins are held together by a tight covalent bond, but the C-terminal cleaved peptide of PAI-1 is only bound to the complex by hydrophobic forces. To assess whether this is specific to the tPA B-chain alone, experiments with the complex of full-length, glycosylated tPA and glycosylated PAI-1 were also performed, and it was possible to demonstrate the release of the C-terminal PAI-1 peptide by chromatography, mass spectrometry, as well as by SDS-PAGE.

Amino Acid Sequence↗

PubMed1995

Carbohydrate specificity of the Escherichia coli P-pilus papG protein is mediated by its N-terminal part.

The adherence of pyelonephritic Escherichia coli isolates to mammalian host cells is mediated by the P-pili structures on the bacterial surface. The protein constituting the distal part of the pili structure, papG, interacts with glycan receptors on the host cell. Variation in specificity for different glycoconjugates between the isolates, that may reflect variation in host tropism, has been correlated to three different classes of papG. Truncated variants of the class I, II and III papG adhesins were produced as fusion protein in E. coli and analysed for carbohydrate binding. The results showed that both carbohydrate binding and specificity of the papG adhesin resided in a linear part of the N-terminus of the protein.

Adhesins, Escherichia coli↗

PubMed1995

Acceptable levels of tonal and broad-band repetitive and continuous sounds during the performance of nonauditory tasks.

Three groups of 24 subjects were exposed to a 1000-Hz tone or broad band noise in a sound chamber. During the exposures subjects were engaged in an easy reaction time test or a difficult grammatical reasoning test. For each exposure and work subjects adjusted the noise to a tolerance level defined by its interference with task performance. During the simple reaction-time task significantly higher sound-pressure levels were accepted than during the reasoning test. At the tonal exposure, much lower levels were accepted than during the exposure to broad-band noise. For continuous sound exposures much higher levels were accepted than for noncontinuous exposures. For tonal exposures the difference was approximately 5 dB, for the broad-band exposures approximately 9 dB. In a separate study the effects of the noncontinuity of the noise and pauses were analysed. The raised annoying effect of the noncontinuous noise was not more affected by the noncontinuity of the noise periods than by the noncontinuity of the pauses. The results imply that the annoying reactions to the sound will be increased for repetitive noise and that the reaction is highly influenced by the over-all noncontinuity of the exposure.

Acoustic Stimulation↗