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- Agbaje, Oluwatoosin B. A., et al.
(författare)
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Biomacromolecules in recent phosphate-shelled brachiopods : identification and characterization of chitin matrix
- 2021
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Ingår i: Journal of Materials Science. - : Springer Nature. - 0022-2461 .- 1573-4803. ; 56:36, s. 19884-19898
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Tidskriftsartikel (refereegranskat)abstract
- Phosphate-shelled brachiopods differ in filter-feeding lifestyle, with Lingula anatina an active infaunal burrower, and Discinisca tenuis a shallow marine epibenthic animal. The shells of these animals are built of organophosphatic constituents, the organic fibres/sheets reinforced with calcium phosphate to provide a sophisticated ultrastructural robustness. This investigation examined the nature of the organic fibres in order to improve understanding of how living organisms produce hierarchically structured biomaterials. Unlike powdered samples commonly used in previous studies, organic fibres were isolated for the first time and the shell fractions were purified, in order to study the content and nature of the biopolymer fibres. Biochemical methods including Calcofluor staining revealed a chitin matrix. Ultrastructural analysis, thermal gravimetric analysis, and spectroscopic analyses show that the core polysaccharide framework is composed of layers of β-chitin sheets and/or fibrils that are coated with a fibrous organic matrix. There is more chitin matrix in the L. anatina shells (26.6 wt.%) compared to the D. tenuis shells (12.9 wt.%). Taken together, the data show that the chitin matrix contributes to increased skeletal strength, making L. anatina highly adapted for life as an active burrower. In comparison, D. tenuis contains less chitin and lives as attached epibenthos in a shallow marine environment.
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- Ament, A, et al.
(författare)
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Cost-Effectiveness of Pneumococcal Vaccination of Older People: A Study in 5 Western European Countries
- 2000
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Ingår i: Clinical infectious diseases. - : The University of Chicago Press. - 1537-6591 .- 1058-4838. ; 31:2, s. 444-450
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Tidskriftsartikel (refereegranskat)abstract
- Pneumococcal vaccination of older persons is thought to be cost-effective in preventing pneumococcal pneumonia, but evidence of clinical protection is uncertain. Because there is better evidence of vaccination effectiveness against invasive pneumococcal disease, we determined the cost-effectiveness of pneumococcal vaccination of persons aged ≥65 years in preventing hospital admission for both invasive pneumococcal disease and pneumococcal pneumonia in 5 western European countries. In the base case analyses, the cost-effectiveness ratios for preventing invasive disease varied from ∼11,000 to ∼33,000 European currency units (ecu) per quality-adjusted life year (QALY). Assuming a common incidence (50 cases per 100,000) and mortality rate (20%-40%) for invasive disease, the cost-effectiveness ratios were <12,000 ecu per QALY in all 5 countries. For preventing pneumococcal pneumonia, vaccinating all elderly persons would be highly cost-effective to cost saving. Public health authorities should consider policies for encouraging pneumococcal vaccination for all persons aged ≥65 years.
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- Allerbring, E. B., et al.
(författare)
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Unexpected T-cell recognition of an altered peptide ligand is driven by reversed thermodynamics
- 2012
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Ingår i: European Journal of Immunology. - : Wiley. - 0014-2980 .- 1521-4141. ; 42:11, s. 2990-3000
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Tidskriftsartikel (refereegranskat)abstract
- The molecular basis underlying T-cell recognition of MHC molecules presenting altered peptide ligands is still not wellestablished. A hierarchy of T-cell activation by MHC class I-restricted altered peptide ligands has been defined using the T-cell receptor P14 specific for H-2Db in complex with the immunodominant lymphocytic choriomeningitis virus peptide gp33 (KAVYNFATM). While substitution of tyrosine to phenylalanine (Y4F) or serine (Y4S) abolished recognition by P14, the TCR unexpectedly recognized H-2Db in complex with the alanine-substituted semiagonist Y4A, which displayed the most significant structural modification. The observed functional hierarchy gp33 > Y4A > Y4S = Y4F was neither due to higher stabilization capacity nor to differences in structural conformation. However, thermodynamic analysis demonstrated that while recognition of the full agonist H-2Db/gp33 was strictly enthalpy driven, recognition of the weak agonist H-2Db/Y4A was instead entropy driven with a large reduction in the favorable enthalpy term. The fourfold larger negative heat capacity derived for the interaction of P14 with H-2Db/gp33 compared with H-2Db/Y4A can possibly be explained by higher water entrapment at the TCR/MHC interface, which is also consistent with the measured opposite entropy contributions for the interactions of P14 with both MHCs. In conclusion, this study demonstrates that P14 makes use of different strategies to adapt to structural modifications in the MHC/peptide complex.
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- Andrews, David J., et al.
(författare)
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Oblique reflections in the Mars Express MARSIS data set : Stable density structures in the Martian ionosphere
- 2014
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Ingår i: Journal of Geophysical Research-Space Physics. - 2169-9380. ; 119:5, s. 3944-3960
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Tidskriftsartikel (refereegranskat)abstract
- The Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) onboard the European Space Agency's Mars Express (MEX) spacecraft routinely detects evidence of localized plasma density structures in the Martian dayside ionosphere. Such structures, likely taking the form of spatially extended elevations in the plasma density at a given altitude, give rise to oblique reflections in the Active Ionospheric Sounder data. These structures are likely related to the highly varied Martian crustal magnetic field. In this study we use the polar orbit of MEX to investigate the repeatability of the ionospheric structures producing these anomalous reflections, examining data taken in sequences of multiple orbits which pass over the same regions of the Martian surface under similar solar illuminations, within intervals lasting tens of days. Presenting three such examples, or case studies, we show for the first time that these oblique reflections are often incredibly stable, indicating that the underlying ionospheric structures are reliably reformed in the same locations and with qualitatively similar parameters. The visibility, or lack thereof, of a given oblique reflection on a single orbit can generally be attributed to variations in the crustal field within the ionosphere along the spacecraft trajectory. We show that, within these examples, oblique reflections are generally detected whenever the spacecraft passes over regions of intense near-radial crustal magnetic fields (i.e., with a cusp-like configuration). The apparent stability of these structures is an important feature that must be accounted for in models of their origin.
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- Candinas, R, et al.
(författare)
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Impact of fusion avoidance on performance of the automatic threshold tracking feature in dual chamber pacemakers: A multicenter prospective randomized study
- 2002
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Ingår i: PACE. - : Wiley. - 1540-8159. ; 25:11, s. 1540-1545
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Tidskriftsartikel (refereegranskat)abstract
- The Autocapture algorithm enables automatic capture verification on a beat-by-beat basis by recognizing the evoked response signal following each pacemaker stimulus. The algorithm intends to increase patient safety while decreasing energy consumption. However, the occurrence of fusion beats, particularly during dual chamber pacing, may limit the energy saving effect of Autocapture. The aim of this multicenter, prospective, randomized study was to evaluate the impact of the Fusion Avoidance (FA) algorithm on the incidence of fusion beats. Thirty-eight patients (mean age 69 +/- 13 years) with intrinsic AV conduction who were implanted with an Affinity DR were studied. After programming a PV/AV delay of 120/190 ms, patients were randomized to FA On or Off. Each group was further randomized with respect to activation of the AutoIntrinsic Conduction Search (AICS) algorithm. The total number of beats, ventricular paced beats, fusion beats, backup pulses, and threshold searches were analyzed from 24-hour Holter recordings. The number of total beats was comparable in both FA groups. The number of total ventricular paced beats, fusion beats, backup pulses, and threshold searches were significantly reduced in the FA On group (% reduction: 68% P < 0.001, 75% P < 0.01, 95% P < 0.01, and 94% P < 0.05, respectively). The number of ventricular paced beats with full capture was significantly reduced when AICS was activated (P < 0.05). In conclusion, the FA algorithm substantially reduces the amount of ventricular paced beats, fusion beats, unnecessary backup pulses and threshold searches, and therefore, provides added benefits in energy saving obtained by Autocapture.
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- Carrick, Richard T., et al.
(författare)
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Implantable cardioverter defibrillator use in arrhythmogenic right ventricular cardiomyopathy in North America and Europe
- 2024
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Ingår i: European Heart Journal. - : OXFORD UNIV PRESS. - 0195-668X .- 1522-9645.
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Tidskriftsartikel (refereegranskat)abstract
- Background and Aims Implantable cardioverter-defibrillators (ICDs) are critical for preventing sudden cardiac death (SCD) in arrhythmogenic right ventricular cardiomyopathy (ARVC). This study aims to identify cross-continental differences in utilization of primary prevention ICDs and survival free from sustained ventricular arrhythmia (VA) in ARVC.Methods This was a retrospective analysis of ARVC patients without prior VA enrolled in clinical registries from 11 countries throughout Europe and North America. Patients were classified according to whether they received treatment in North America or Europe and were further stratified by baseline predicted VA risk into low- (<10%/5 years), intermediate- (10%-25%/5 years), and high-risk (>25%/5 years) groups. Differences in ICD implantation and survival free from sustained VA events (including appropriate ICD therapy) were assessed.Results One thousand ninety-eight patients were followed for a median of 5.1 years; 554 (50.5%) received a primary prevention ICD, and 286 (26.0%) experienced a first VA event. After adjusting for baseline risk factors, North Americans were more than three times as likely to receive ICDs {hazard ratio (HR) 3.1 [95% confidence interval (CI) 2.5, 3.8]} but had only mildly increased risk for incident sustained VA [HR 1.4 (95% CI 1.1, 1.8)]. North Americans without ICDs were at higher risk for incident sustained VA [HR 2.1 (95% CI 1.3, 3.4)] than Europeans.Conclusions North American ARVC patients were substantially more likely than Europeans to receive primary prevention ICDs across all arrhythmic risk strata. A lower rate of ICD implantation in Europe was not associated with a higher rate of VA events in those without ICDs.
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