| 1. |
|
|
| 2. |
|
|
| 3. |
- Janulczyk, Robert, et al.
(författare)
-
Improved pattern for genome-based screening identifies novel cell wall-attached proteins in gram-positive bacteria
- 2001
-
Ingår i: Infection and Immunity. - 1098-5522. ; 69:6, s. 4019-4026
-
Tidskriftsartikel (refereegranskat)abstract
- With a large number of sequenced microbial genomes available, tools for identifying groups or classes of proteins have become increasingly important. Here we present an improved pattern for the identification of cell wall-attached proteins (CWPs), a group of proteins with diverse and important functions in gram-positive bacteria. This tripartite pattern is based on analysis of 65 previously described cell wall-attached proteins and takes into account the three principal requirements for cell wall sorting; a sortase target region (LPXTGX), a membrane-spanning region, and a charged stop-transfer tail. In five different genomes of gram-positive bacteria, the tripartite pattern identified a total of 35 putative CWPs, 19 of which were novel. The specificity and sensitivity of the tripartite pattern are higher than those of the classical pattern, which is based solely on the sortase target region. Several putative CWPs with atypical sortase target regions were identified. In the complete genome of the important human pathogen Streptococcus pyogenes, the tripartite pattern identified 14 putative CWPs. Seven of the putative S. pyogenes proteins were novel, and two of these were a 5' nucleotidase and a pullulanase. This study represents the first whole-genome screening for CWPs, and we conclude that the tripartite pattern is highly suitable for this purpose. Identification of CWPs using this pattern offers important possibilities in the study of the pathogenesis and physiology of gram-positive bacteria.
|
|
| 4. |
- Johansson, Magnus, et al.
(författare)
-
Statistical mechanics of general discrete nonlinear Schrödinger models : Localization transition and its relevance for Klein-Gordon lattices
- 2004
-
Ingår i: Physical Review E - Statistical, Nonlinear, and Soft Matter Physics. - 1539-3755. ; 70:6 2
-
Tidskriftsartikel (refereegranskat)abstract
- A statistical-mechanics description of a general class of discrete nonlinear Schrödinger (DNLS) models, was presented. Simple analytical conditions for the transition into the statistical localization regime, were obtained. Numerical simulation was performed to show the nature of the localization dynamics outside the 'normal' Gibbsian regime for various cases. It is concluded that the results from the DNLS model can be transferred into approximate conditions for statistical formation of long-lived breathers in weakly coupled Klein-Gordon chains.
|
|
| 5. |
- Kongstad Rasmussen, Ole, et al.
(författare)
-
Global and local dispersion of ventricular repolarization: endocardial monophasic action potential mapping in swine and humans by using an electro-anatomical mapping system.
- 2002
-
Ingår i: Journal of Electrocardiology. - : Elsevier BV. - 1532-8430 .- 0022-0736. ; 35:2, s. 159-167
-
Tidskriftsartikel (refereegranskat)abstract
- This article evaluates whether the global dispersion of ventricular repolarization (DVR) can be estimated from measurements between a few adjacent or remote sites. Monophasic action potentials (MAP) were recorded from 61 +/- 18 left (LV) or right ventricular (RV) sites in 10 pigs and 44 +/- 16 LV, or RV sites in 8 patients by using the CARTO mapping system. MAP duration (MAPd) and end-of-repolarization time were calculated at each site and 13 repolarization maps from pigs and 10 from patients were reconstructed. Global dispersions in MAPd and EOR over the LV or RV were compared with the adjacent DVR among 3 - 7 MAPs in areas > or = 0.7 and < or = 1 cm(2) and with the remote DVRs between 2 MAPs with the greatest activation time difference (remote DVR1) and between the apical and laterobasal LV or RV (remote DVR2). The adjacent dispersions in end-of-repolarization and MAPd were significantly smaller than the global ones, 13 +/- 3 and 12 +/- 3 ms vs. 44 +/- 9 and 42 +/- 12 ms in pigs and 13 +/- 7 and 14 +/- 8 ms vs. 72 +/- 24 and 66 +/- 22 ms in patients. The remote DVR1 (30 +/- 8 and 17 +/- 10 ms in pigs and 40 +/- 28 and 28 +/- 17 ms in patients) and remote DVR2 (16 +/- 7 and 11 +/- 10 ms in pigs and 35 +/- 24 and 21 +/- 21 ms in patients) were also significantly smaller than the global DVRs. In conclusion, global DVR is poorly estimated from MAP recordings from a few adjacent or remote sites, suggesting the importance of obtaining global information in evaluating DVR.
|
|
| 6. |
|
|
| 7. |
- Liu, Shaowen, et al.
(författare)
-
Monophasic Action Potential Mapping in Swine and Humans Using Modified-tip Ablation Catheter and Electroanatomic Mapping System.
- 2002
-
Ingår i: Scandinavian Cardiovascular Journal. - 1651-2006. ; 36:3, s. 161-166
-
Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To evaluate the feasibility of monophasic action potential (MAP) mapping using a modified-tip NaviStar catheter in swine and humans. METHODS: MAP mapping was performed using the modified-tip catheter at 71 +/- 21 atrial and 60 +/- 16 ventricular sites in 10 healthy pigs and at 56 ventricular sites in one patient, and using an ordinary Navi-Star catheter at 30 atrial sites in one patient and 50 +/- 14 ventricular sites in four patients. In an additional 20 patients, MAPs were also recorded at 9 +/- 2 atrial sites using the modified-tip catheter or at 12 +/- 9 atrial sites using the ordinary catheter. RESULTS: In pigs, the plateau amplitudes of the MAPs recorded using the modified-tip catheter were 4.1 +/- 3.2 mV for the atrial and 9.5 +/- 4.3 mV for the ventricular MAPs. In patients, both the ventricular and atrial MAPs recorded using the modified-tip catheter were significantly higher than using the ordinary catheters, 15.7 +/- 8 and 3.0 +/- 0.9 mV vs 9.5 +/- 3.9 and 2.0 +/- 0.6 mV for the ventricular and atrial MAPs, respectively (p < 0.0001). The baseline disturbances were <10% of the MAP amplitude in 95% of the pig and 96% of the patient MAPs. CONCLUSION: A modified-tip Navi-Star catheter could be used in swine and in humans for prompt recording of MAPs with acceptable amplitudes and baselines. MAP mapping using the modified-tip catheter is safe and feasible for clinical use.
|
|
| 8. |
|
|
| 9. |
|
|
| 10. |
|
|
| 11. |
- Nyberg, Patrik, et al.
(författare)
-
SpeB modulates fibronectin-dependent internalization of Streptococcus pyogenes by efficient proteolysis of cell-wall-anchored protein F1.
- 2004
-
Ingår i: Microbiology. - : Microbiology Society. - 1465-2080 .- 1350-0872. ; 150:Pt 5, s. 1559-1569
-
Tidskriftsartikel (refereegranskat)abstract
- SpeB is a cysteine proteinase and virulence determinant secreted by the important human pathogen Streptococcus pyogenes. Recent investigations have suggested a role for SpeB in streptococcal entry into human cells. However, conflicting data concerning the contribution of SpeB to internalization have been presented. Protein F1 is a cell-wall-attached fibronectin (Fn)-binding protein that is present in a majority of streptococcal isolates and is important for internalization. This study shows that protein F1 is efficiently degraded by SpeB, and that removal of protein F1 from the bacterial surface leads to reduced internalization. Whereas M1 protein and protein H, two additional surface proteins of S. pyogenes that bind human plasma proteins, are protected from proteolytic degradation by their ligands, protein F1 is readily cleaved by SpeB also when in complex with Fn. This finding, and the connection between the presence of Fn at the bacterial surface and entry into human cells, suggest that SpeB plays a role in the regulation of the internalization process.
|
|
| 12. |
|
|
| 13. |
|
|
| 14. |
|
|
| 15. |
- Rasmussen, Magnus, et al.
(författare)
-
Genome-based identification and analysis of collagen-related structural motifs in bacterial and viral proteins.
- 2003
-
Ingår i: Journal of Biological Chemistry. - 1083-351X. ; 278:34, s. 32313-32316
-
Tidskriftsartikel (refereegranskat)abstract
- Collagens are extended trimeric proteins composed of the repetitive sequence glycine-X-Y. A (c) under bar ollagen- related (S) under bar tructural (m) under bar otif (CSM) containing glycine-X-Y repeats is also found in numerous proteins often referred to as collagen-like proteins. Little is known about CSMs in bacteria and viruses, but the occurrence of such motifs has recently been demonstrated. Moreover, bacterial CSMs form collagen-like trimers, even though these organisms cannot synthesize hydroxyproline, a critical residue for the stability of the collagen triple helix. Here we present 100 novel proteins of bacteria and viruses (including bacteriophages) containing CSMs identified by in silico analyses of genomic sequences. These CSMs differ significantly from human collagens in amino acid content and distribution; bacterial and viral CSMs have a lower proline content and a preference for proline in the X position of GXY triplets. Moreover, the CSMs identified contained more threonine than collagens, and in 17 of 53 bacterial CSMs threonine was the dominating amino acid in the Y position. Molecular modeling suggests that threonines in the Y position make direct hydrogen bonds to neighboring backbone carbonyls and thus substitute for hydroxyproline in the stabilization of the collagen-like triple-helix of bacterial CSMs. The majority of the remaining CSMs were either rich in proline or rich in charged residues. The bacterial proteins containing a CSM that could be functionally annotated were either surface structures or spore components, whereas the viral proteins generally could be annotated as structural components of the viral particle. The limited occurrence of CSMs in eubacteria and lower eukaryotes and the absence of CSMs in archaebacteria suggests that DNA encoding CSMs has been transferred horizontally, possibly from multicellular organisms to bacteria.
|
|
| 16. |
- Rasmussen, Magnus, et al.
(författare)
-
Proteolysis and its regulation at the surface of Streptococcus pyogenes.
- 2002
-
Ingår i: Molecular Microbiology. - : Wiley. - 1365-2958 .- 0950-382X. ; 43:3, s. 537-544
-
Forskningsöversikt (refereegranskat)abstract
- Pathogenic bacteria often produce proteinases that are believed to be involved in virulence. Moreover, several host defence systems depend on proteolysis, demonstrating that proteolysis and its regulation play an important role during bacterial infections. Here, we discuss how proteolytical events are regulated at the surface of Streptococcus pyogenes during infection with this important human pathogen. Streptococcus pyogenes produces proteinases, and host proteinases are produced and released as a result of the infection. Streptococcus pyogenes also recruits host proteinase inhibitors to its surface, suggesting that proteolysis is tightly regulated at the bacterial surface. We propose that the initial phase of a S. pyogenes infection is characterized by inhibition of proteolysis and complement activity at the bacterial surface. This is achieved mainly through binding of host proteinase inhibitors and complement regulatory proteins to bacterial surface proteins. In a later phase of the infection, massive proteolytic activity will release bacterial surface proteins and degrade human tissues, thus facilitating bacterial spread. These proteolytic events are regulated both temporally and spatially, and should influence virulence and the outcome of S. pyogenes infections.
|
|
| 17. |
- Rasmussen, Magnus, et al.
(författare)
-
SclA, a novel collagen-like surface protein of Streptococcus pyogenes
- 2000
-
Ingår i: Infection and Immunity. - 1098-5522. ; 68:11, s. 6370-6377
-
Tidskriftsartikel (refereegranskat)abstract
- Surface proteins of Streptococcus pyogenes are important virulence factors. Here we describe a novel collagen-like surface protein, designated SclA (streptococcal collagen-like surface protein). The sclA gene was identified in silico using the Streptococcal Genome Sequencing Project with the recently identified protein GRAB as the probe. SclA has a signal sequence and a cell wall attachment region containing the prototypic LPXTGX motif. The surface-exposed part of SclA contains a unique NH(2)-terminal domain of 73 amino acids, followed by a collagen-like region. The sclA gene was found to be positively regulated by Mga, a transcriptional activator of several S. pyogenes virulence determinants. A mutant lacking cell wall-associated SclA was constructed and was found to be as effective as wild-type bacteria in platelet aggregation, survival in fresh human blood, and adherence to pharyngeal cells. The sclA gene was found in all 12 S. pyogenes strains that were investigated using PCR. Sequence analysis revealed that the signal sequence and the cell wall attachment region are highly conserved. The collagen-like domain is variable in its NH(2)-terminal region and has conserved repeated domains in its COOH-terminal part. SclA proteins from most strains have additional proline-rich repeats spacing the collagen-like domain and the cell wall attachment sequence. The unique NH(2)-terminal region is hypervariable, but computer predictions indicate a common secondary structure, with two alpha helices connected by a loop region. Immune selection may explain the hypervariability in the NH(2)-terminal region, whereas the preserved secondary structure implies that this region has a common function. These features and the Mga regulation are shared with the M protein of S. pyogenes. Moreover, as with the gene encoding the M protein, phylogenetic analysis indicates that horizontal gene transfer has contributed to the evolution of sclA.
|
|
| 18. |
- Rasmussen, Magnus
(författare)
-
Studies on cell wall-attached proteins of Streptococcus pyogenes
- 2001
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Cell wall-attached proteins (CWPs) are important for the virulence of Gram-positive bacteria, but are also targets for the host immune system. CWPs have a conserved COOH-terminal region, responsible for cell wall-sorting. A pattern based on this conserved region was developed. The pattern identifies genes encoding CWPs, with high sensitivity and specificity, in whole genomes of Gram-positive bacteria. In genomes of five Gram-positive bacterial species, 19 previously unknown putative CWPs were identified. Three novel CWPs were identified and characterised in Streptococcus pyogenes, an important Gram-positive human pathogen. One CWP, GRAB, binds the human proteinase inhibitor alpha2-macroglobulin to the S. pyogenes surface, thus protecting other CWPs from proteolysis. Moreover, two novel CWPs (SclA and SclB) with regions similar to collagen were studied. These CWPs have a hypervariable NH2-terminal region and a more conserved COOH-terminal collagen-like region. The genes encoding GRAB and the Scl proteins are present in almost all S. pyogenes strains, indicating that these CWPs have important functions. The sclA gene is regulated by Mga, a transcriptional activator of many S. pyogenes genes related to virulence. In contrast, expression of SclB is regulated by repeated DNA sequences affecting protein translation. The repeated sequences facilitate genetic variation and mediate phase variation of SclB. In addition, insertion sequences could also contribute to genetic variation. One insertion sequence, IS1562, was identified in a region of the S. pyogenes chromosome encoding virulence factors.
|
|
| 19. |
- Rasmussen, Magnus, et al.
(författare)
-
Unique regulation of SclB - a novel collagen-like surface protein of Streptococcus pyogenes
- 2001
-
Ingår i: Molecular Microbiology. - : Wiley. - 1365-2958 .- 0950-382X. ; 40:6, s. 1427-1438
-
Tidskriftsartikel (refereegranskat)abstract
- Slipped-strand mispairing at sites containing so-called coding repeats (CRs) can lead to phase variation of surface proteins in Gram-negative bacteria. This mechanism, believed to contribute to virulence, has so far not been identified in a Gram-positive bacterium. In the genome of the Gram-positive human pathogen Streptococcus pyogenes, we identified pentanucleotide CRs within a putative signal sequence of an open reading frame (ORF) encoding a novel collagen-like surface protein, denoted SclB. In 12 S. pyogenes strains, the number of CRs in the sclB gene varied from three to 19, rendering the start codon in frame with the downstream ORF in four strains and out of frame in eight strains. A protein reacting with anti-SclB antibodies could only be solubilized from three strains, all containing an intact sclB gene. Variations in the number of CRs were observed within strains of the same M serotype and occurred during growth of S. pyogenes in fresh human blood, but not in medium. The SclB protein has a hypervariable N-terminal part, a collagen-like central part and a typical cell wall sorting sequence containing the LPXTGX motif. SclB is related to the collagen-like SclA and is, like SclA, involved in the adhesion of S. pyogenes bacteria to human cells. However, the Mga protein, known to upregulate sclA and several additional genes encoding virulence factors of S. pyogenes, downregulates sclB transcription. This observation and the potential of SclB to phase vary by slipped-strand mispairing emphasize the unique regulation of this novel S. pyogenes surface protein.
|
|
| 20. |
- Sundbom, Magnus, et al.
(författare)
-
[Hepatic trauma--a 10-year Swedish study. Conservative treatment generally the best option when the circulation is stable].
- 2002
-
Ingår i: Läkartidningen. - 0023-7205 .- 1652-7518. ; 99:10, s. 1063-5, 1068
-
Tidskriftsartikel (refereegranskat)abstract
- We studied retrospectively 60 patients with hepatic injuries, 30 of which were referrals. Blunt trauma dominated (90%). Twelve unstable patients had immediate surgery and 41 an initial CT-scan. The injury was graded according to the Liver Injury Scale (AAST). Moderate injuries (grade I-II) were seen in 40 patients, of which 29 had successful conservative treatment. Fifteen of the severe injuries required surgery. Minimally invasive techniques facilitated management of postoperative complications. In all, 16 died, 4 due to the hepatic injury. The material presented is small and heterogeneous, but our results are similar to those reported internationally. A multidisciplinary approach facilitates management.
|
|
| 21. |
- Toppel, AW, et al.
(författare)
-
Contribution of protein G-related alpha(2)-macroglobulin-binding protein to bacterial virulence in a mouse skin model of group a streptococcal infection
- 2003
-
Ingår i: Journal of Infectious Diseases. - 1537-6613. ; 187:11, s. 1694-1703
-
Tidskriftsartikel (refereegranskat)abstract
- Protein G-related alpha(2)-macroglobulin-binding (GRAB) protein is a cell wall-attached determinant of group A streptococcus (GAS) that interacts with the human protease inhibitor a 2-macroglobulin (alpha(2)-M). Of 86 clinical isolates tested, 23% could bind a alpha(2)-M. However, all strains tested contained the grab gene. High levels of anti-GRAB antibodies were found in the serum of convalescent GAS-infected patients, a finding that indicates that this protein is expressed during the infection process. Among the alpha(2)-M-binding strains, 80% were skin isolates, and 20% were throat isolates, findings that suggest that the skin environment is a preferential site for expression of alpha(2)-M-binding activity. To test this possibility, we determined the role of GRAB in a mouse model of GAS skin infection. The wild-type strain KTL3, which interacts with alpha(2)-M, showed high virulence. The isogenic mutant of KTL3, MR4, devoid of surface-bound GRAB, was attenuated in virulence, compared with the wildtype strain. Thus, mice infected with MR4 survived longer, developed smaller skin lesions, and exhibited lower levels of bacterial dissemination than did those infected with KTL3. These results emphasize the role of GRAB as a virulence factor of GAS.
|
|
| 22. |
|
|
| 23. |
- Yuan, Shiwen, et al.
(författare)
-
Global repolarization sequence of the ventricular endocardium: Monophasic action potential mapping in swine and humans
- 2001
-
Ingår i: PACE. - : Wiley. - 1540-8159. ; 24:10, s. 1479-1488
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to evaluate the global sequence of repolarization over the ventricular endocardium. Disturbances in myocardial repolarization are associated with the genesis of arrhythmias. However, little is known about the global sequence of repolarization. Monophasic action potentials (MAPs) were recorded from 61 +/- 18 LV and/or RV sites in ten healthy pigs and from 43 +/- 15 LV or RV sites in eight patients using the CARTO system. Local activation time (AT), end-of-repolarization (EOR) time, and MAP duration were calculated and three-dimensional global maps of AT, EOR, and MAP duration constructed. LV maps were obtained from all ten pigs and RV maps from three pigs. Five RV maps and five LV maps were obtained from the eight patients. (1) EOR sequence was recognizable in 12 of 13 pig maps and in all the patient maps. (2) EOR followed the sequence of activation in 12 of 13 pig maps and 8 of 10 patient maps. (3) The longest MAPs were recorded in or near the earliest activation area, and the shortest ones in or near the latest activation area in all the pig maps and in nine of ten and eight of ten patient maps, respectively. (4) In all maps, MAP duration and AT were negatively correlated, and EOR and AT positively correlated. In conclusion, repolarization gradients exist over the pig and the human ventricular endocardium. The activation sequence is a determinant for the repolarization sequence. The magnitude of the progressive MAP shortening with progressively later activation, relative to local AT, is a critical factor governing the direction and pattern of the EOR.
|
|
| 24. |
|
|
