| 1. |
- Gustafsson, G, et al.
(författare)
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The electric field and wave experiment for the Cluster mission
- 1997
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Ingår i: Space Science Reviews. - 0038-6308 .- 1572-9672. ; 79, s. 137-156
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Tidskriftsartikel (refereegranskat)abstract
- The electric-field and wave experiment (EFW) on Cluster is designed to measure the electric-field and density fluctuations with sampling rates up to 36 000 samples s(-1). Langmuir probe sweeps can also be made to determine the electron density and temperature. The instrument has several important capabilities. These include (1) measurements of quasi-static electric fields of amplitudes lip to 700 mV m(-1) with high amplitude and time resolution, (2) measurements over short periods of time of up to five simualtaneous waveforms (two electric signals and three magnetic signals from the seach coil magnetometer sensors) of a bandwidth of 4 kHz with high time resolution, (3) measurements of density fluctuations in four points with high time resolution. Among the more interesting scientific objectives of the experiment are studies of nonlinear wave phenomena that result in acceleration of plasma as well as large- and small-scale interferometric measurements. By using four spacecraft for large-scale differential measurements and several Langmuir probes on one spacecraft for small-scale interferometry, it will be possible to study motion and shape of plasma structures on a wide range of spatial and temporal scales. This paper describes the primary scientific objectives of the EFW experiment and the technical capabilities of the instrument.
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| 2. |
- Berggård, T, et al.
(författare)
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Alpha1-microglobulin chromophores are located to three lysine residues semiburied in the lipocalin pocket and associated with a novel lipophilic compound
- 1999
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Ingår i: Protein Science. - : Wiley. - 0961-8368. ; 8:12, s. 20-2611
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Tidskriftsartikel (refereegranskat)abstract
- Alpha1-microglobulin (alpha1m) is an electrophoretically heterogeneous plasma protein. It belongs to the lipocalin superfamily, a group of proteins with a three-dimensional (3D) structure that forms an internal hydrophobic ligand-binding pocket. Alpha1m carries a covalently linked unidentified chromophore that gives the protein a characteristic brown color and extremely heterogeneous optical properties. Twenty-one different colored tryptic peptides corresponding to residues 88-94, 118-121, and 122-134 of human alpha1m were purified. In these peptides, the side chains of Lys92, Lys118, and Lys130 carried size heterogeneous, covalently attached, unidentified chromophores with molecular masses between 122 and 282 atomic mass units (amu). In addition, a previously unknown uncolored lipophilic 282 amu compound was found strongly, but noncovalently associated with the colored peptides. Uncolored tryptic peptides containing the same Lys residues were also purified. These peptides did not carry any additional mass (i.e., chromophore) suggesting that only a fraction of the Lys92, Lys118, and Lys130 are modified. The results can explain the size, charge, and optical heterogeneity of alpha1m. A 3D model of alpha1m, based on the structure of rat epididymal retinoic acid-binding protein (ERABP), suggests that Lys92, Lys118, and Lys130 are semiburied near the entrance of the lipocalin pocket. This was supported by the fluorescence spectra of alpha1m under native and denatured conditions, which indicated that the chromophores are buried, or semiburied, in the interior of the protein. In human plasma, approximately 50% of alpha1m is complex bound to IgA. Only the free alpha1m carried colored groups, whereas alpha1m linked to IgA was uncolored.
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| 3. |
- Gustafsson, G, et al.
(författare)
-
The electric field and wave experiment for the Cluster mission
- 1997
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Ingår i: SPACE SCIENCE REVIEWS. - : KLUWER ACADEMIC PUBL. - 0038-6308. ; 79:1-2, s. 137-156
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Tidskriftsartikel (refereegranskat)abstract
- The electric-field and wave experiment (EFW) on Cluster is designed to measure the electric-field and density fluctuations with sampling rates up to 36 000 samples s(-1). Langmuir probe sweeps can also be made to determine the electron density and tempera
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| 4. |
- Andréassob, A-Ch, et al.
(författare)
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Characteristics and outcome among patients with a suspected in hospital cardiac arrest
- 1998
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Ingår i: Resuscitation. - : Elsevier Ireland Ltd. - 0300-9572 .- 1873-1570. ; 39:1-2, s. 23-31
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Tidskriftsartikel (refereegranskat)abstract
- AIM: To describe the characteristics and outcome among patients with a suspected in-hospital cardiac arrest. METHODS: All the patients who suffered from a suspected in-hospital cardiac arrest during a 14-months period, where the cardiopulmonary resuscitation (CPR) team was called, were recorded and described prospectively in terms of characteristics and outcome. RESULTS: There were 278 calls for the CPR team. Of these, 216 suffered a true cardiac arrest, 16 a respiratory arrest and 46 neither. The percentage of patients who were discharged alive from hospital was 42% for cardiac arrest patients, 62% for respiratory arrest and 87% for the remaining patients. Among patients with a cardiac arrest, those found in ventricular fibrillation/ventricular tachycardia had a survival rate of 64%, those found in asystole 24% and those found in pulseless electrical activity 10%. Among patients who were being monitored at the time of arrest, the survival rate was 52%, as compared with 27% for non-monitored patients (P= 0.001). Among survivors of cardiac arrest, a cerebral performance category (CPC) of 1 (no major deficit) was observed in 81% at discharge and in 82% on admission to hospital prior to the arrest. CONCLUSION: We conclude that, during a 14-month period at Sahlgrenska University Hospital in Göteborg, almost half the patients with a cardiac arrest in which the CPR team was called were discharged from hospital. Among survivors, 81% had a CPC score of 1 at hospital discharge. Survival seems to be closely related to the relative effectiveness of the resuscitation organisation in different parts of the hospital.
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| 5. |
- Karlson, BW, et al.
(författare)
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Improvement of ED prediction of cardiac mortality among patients with symptoms suggestive of acute myocardial infarction
- 1997
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Ingår i: American Journal of Emergency Medicine. - : W.B. Saunders Co.. - 0735-6757 .- 1532-8171. ; 15:1, s. 1-7
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Tidskriftsartikel (refereegranskat)abstract
- A study was undertaken to evaluate the 1-year risk of cardiac death for patients with chest pain/suspected acute myocardial infarction in the emergency department (ED) and express the prognosis in a statistical model. Clinical variables and electrocardiogram were correlated to cardiac death during 1 year. Cox regression model was used to estimate the risk of death as a continuous function of a risk score and the time interval. From these, the prognosis for each patient can be calculated. There were 6,794 visits by 5,303 patients followed for 1 year, during which 604 patients died. The absolute risk of cardiac death can be calculated from the independent predictors for cardiac death: age; sex; histories of diabetes mellitus, hypertension, and congestive heart failure; and symptoms, electrocardiographic pattern, and degree of suspicion of acute myocardial infarction on admission. This model allows estimation of the prognosis for every patient with chest pain/suspected acute myocardial infarction from data easily available in the ED.
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| 6. |
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| 7. |
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| 8. |
- Akerström, B, et al.
(författare)
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Binding properties of protein Arp, a bacterial IgA-receptor
- 1991
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Ingår i: Molecular Immunology. - 0161-5890. ; 28:4-5, s. 57-349
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Tidskriftsartikel (refereegranskat)abstract
- A cell surface receptor that binds to the Fc region of IgA is expressed by certain strains of group A streptococci. The physico-chemical properties and binding characteristics of this receptor, called protein Arp, were studied. Like bacterial receptors that bind IgG, protein Arp has an elongated shape and no disulfide bonds. The affinity constant of protein Arp for three different molecular forms of IgA was determined, and was found to be more than ten-fold higher for serum IgA than for two complexed forms of IgA: secretory IgA and IgA bound to alpha 1-microglobulin. Cleavage of protein Arp with CNBr resulted in a peptide corresponding to the region located outside the cell wall, except for the N-terminal 52 amino acids. This CNBr-fragment did not bind IgA, which strongly suggests that the IgA-binding region of protein Arp is located in the N-terminal part of the molecule. In addition to the binding of IgA, protein Arp also binds to IgG weakly. The pH-dependence of these two types of binding is different, with maximal binding of IgA at neutral pH (5-7) and maximal binding of IgG at acidic pH (3-5). Both for IgA and IgG, protein Arp shows strong specificity for immunoglobulins of human origin.
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| 9. |
- Akerström, B, et al.
(författare)
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Protein Arp and protein H from group A streptococci. Ig binding and dimerization are regulated by temperature
- 1992
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Ingår i: Journal of immunology. - 0022-1767. ; 148:10, s. 43-3238
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Tidskriftsartikel (refereegranskat)abstract
- Cell surface proteins that bind to the Fc part of Ig are expressed by many strains of group A streptococci, an important human pathogen. Two such bacterial strains, AP4 and AP1, were shown to bind IgA and IgG, respectively, in a temperature-dependent manner. The binding of radiolabeled Ig to the bacterial cells was lower at 37 degrees C than at 22 and 4 degrees C. Similarly, protein Arp, the IgA-binding protein isolated from strain AP4, and protein H, the IgG-binding protein isolated from strain AP1, displayed a strong Ig-binding at 22 degrees C and lower temperatures, and virtually no binding at all at 37 degrees C. The effect was reversible: lowering of the temperature restored the binding and vice versa. A gradual shift between binding and nonbinding took place between 27 and 37 degrees C. Gel chromatography and velocity sedimentation centrifugation showed that protein Arp and protein H appeared as noncovalently associated dimers at 10 and 22 degrees C, and as monomers at 37 degrees C. These results strongly suggest that the dimerization of protein Arp and protein H, rather than the low temperature itself, yielded the strong Ig-binding of the proteins at 10 and 22 degrees C. Indeed, after covalent cross-linking of the dimers at 10 degrees C by incubation with low concentrations of glutaraldehyde, full Ig-binding was achieved even at 37 degrees C. A carboxyl-terminal proteolytic fragment of protein Arp, which completely lacked the IgA-binding capacity at any temperature, showed the same temperature-dependent dimerization as intact protein Arp, suggesting that the Ig-binding part of the protein is not required for dimerization. The implications of these results for the function of Ig-binding group A streptococcal proteins, and their role in the host-parasite relationship are discussed.
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