| 1. |
- Escaned, Javier, et al.
(author)
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Safety of the Deferral of Coronary Revascularization on the Basis of Instantaneous Wave-Free Ratio and Fractional Flow Reserve Measurements in Stable Coronary Artery Disease and Acute Coronary Syndromes
- 2018
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In: JACC. - : Elsevier. - 1936-8798 .- 1876-7605. ; 11:15, s. 1437-1449
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Journal article (peer-reviewed)abstract
- OBJECTIVES The aim of this study was to investigate the clinical outcomes of patients deferred from coronary revascularization on the basis of instantaneous wave-free ratio (iFR) or fractional flow reserve (FFR) measurements in stable angina pectoris (SAP) and acute coronary syndromes (ACS). BACKGROUND Assessment of coronary stenosis severity with pressure guidewires is recommended to determine the need for myocardial revascularization. METHODS The safety of deferral of coronary revascularization in the pooled per-protocol population (n = 4,486) of the DEFINE-FLAIR (Functional Lesion Assessment of Intermediate Stenosis to Guide Revascularisation) and iFR-SWEDEHEART (Instantaneous Wave-Free Ratio Versus Fractional Flow Reserve in Patients With Stable Angina Pectoris or Acute Coronary Syndrome) randomized clinical trials was investigated. Patients were stratified according to revascularization decision making on the basis of iFR or FFR and to clinical presentation (SAP or ACS). The primary endpoint was major adverse cardiac events (MACE), defined as the composite of all-cause death, nonfatal myocardial infarction, or unplanned revascularization at 1 year. RESULTS Coronary revascularization was deferred in 2,130 patients. Deferral was performed in 1,117 patients (50%) in the iFR group and 1,013 patients (45%) in the FFR group (p < 0.01). At 1 year, the MACE rate in the deferred population was similar between the iFR and FFR groups (4.12% vs. 4.05%; fully adjusted hazard ratio: 1.13; 95% confidence interval: 0.72 to 1.79; p = 0.60). A clinical presentation with ACS was associated with a higher MACE rate compared with SAP in deferred patients (5.91% vs. 3.64% in ACS and SAP, respectively; fully adjusted hazard ratio: 0.61 in favor of SAP; 95% confidence interval: 0.38 to 0.99; p = 0.04). CONCLUSIONS Overall, deferral of revascularization is equally safe with both iFR and FFR, with a low MACE rate of about 4%. Lesions were more frequently deferred when iFR was used to assess physiological significance. In deferred patients presenting with ACS, the event rate was significantly increased compared with SAP at 1 year. (C) 2018 The Authors. Published by Elsevier on behalf of the American College of Cardiology Foundation.
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| 2. |
- Fager, Cecilia, 1990, et al.
(author)
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Correlating 3D porous structure in polymer films with mass transport properties using FIB-SEM tomography
- 2021
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In: Chemical Engineering Science: X. - : Elsevier BV. - 2590-1400. ; 12
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Journal article (peer-reviewed)abstract
- Porous polymer coatings are used to control drug release from pharmaceutical products. The coating covers a drug core and depending on the porous structure, different drug release rates are obtained. This work presents mass transport simulations performed on porous ethyl cellulose films with different porosities. The simulations were performed on high spatial resolution 3D data obtained using a focused ion beam scanning electron microscope. The effective diffusion coefficient of water was determined using a diffusion chamber. Lattice Boltzmann simulations were used to simulate water diffusion in the 3D data. The simulated coefficient was in good agreement with the measured coefficient. From the results it was concluded that the tortuosity and constrictivity of the porous network increase with decreasing amount of added hydroxypropyl cellulose, resulting in a sharp decrease in effective diffusion. This work shows that high spatial resolution 3D data is necessary, and that 2D data is insufficient, in order to predict diffusion through the porous structure with high accuracy.
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| 3. |
- Antonsson, Jakob, et al.
(author)
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Modeling Colloidal Particle Aggregation Using Cluster Aggregation with Multiple Particle Interactions
- 2024
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In: Journal of Physical Chemistry B. - 1520-6106 .- 1520-5207. ; 128:18, s. 4513-4524
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Journal article (peer-reviewed)abstract
- In this study, we investigate the aggregation dynamics of colloidal silica by generating simulated structures and comparing them to experimental data gathered through scanning transmission electron microscopy (STEM). More specifically, diffusion-limited cluster aggregation and reaction-limited cluster aggregation models with different functions for the probability of particles sticking upon contact were used. Aside from using a constant sticking probability, the sticking probability was allowed to depend on the masses of the colliding clusters and on the number of particles close to the collision between clusters. The different models of the sticking probability were evaluated based on the goodness-of-fit of spatial summary statistics. Furthermore, the models were compared to the experimental data by calculating the structures’ fractal dimension and mass transport properties from simulations of flow and diffusion. The sticking probability, depending on the interaction with multiple particles close to the collision site, led to structures most similar to the STEM data.
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| 4. |
- Fazey, Ioan, et al.
(author)
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Transforming knowledge systems for life on Earth : Visions of future systems and how to get there
- 2020
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In: Energy Research & Social Science. - : Elsevier. - 2214-6296 .- 2214-6326. ; 70
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Journal article (peer-reviewed)abstract
- Formalised knowledge systems, including universities and research institutes, are important for contemporary societies. They are, however, also arguably failing humanity when their impact is measured against the level of progress being made in stimulating the societal changes needed to address challenges like climate change. In this research we used a novel futures-oriented and participatory approach that asked what future envisioned knowledge systems might need to look like and how we might get there. Findings suggest that envisioned future systems will need to be much more collaborative, open, diverse, egalitarian, and able to work with values and systemic issues. They will also need to go beyond producing knowledge about our world to generating wisdom about how to act within it. To get to envisioned systems we will need to rapidly scale methodological innovations, connect innovators, and creatively accelerate learning about working with intractable challenges. We will also need to create new funding schemes, a global knowledge commons, and challenge deeply held assumptions. To genuinely be a creative force in supporting longevity of human and non-human life on our planet, the shift in knowledge systems will probably need to be at the scale of the enlightenment and speed of the scientific and technological revolution accompanying the second World War. This will require bold and strategic action from governments, scientists, civic society and sustained transformational intent.
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| 5. |
- Hamngren Blomqvist, Charlotte, 1984, et al.
(author)
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Interconnectivity imaged in three dimensions : Nano-particulate silica-hydrogel structure revealed using electron tomography
- 2017
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In: Micron. - : Elsevier BV. - 0968-4328 .- 1878-4291. ; 100, s. 91-105
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Journal article (peer-reviewed)abstract
- We have used Electron Tomography (ET) to reveal the detailed three-dimensional structure of particulate hydrogels, a material category common in e.g. controlled release, food science, battery and biomedical applications. A full understanding of the transport properties of these gels requires knowledge about the pore structure and in particular the interconnectivity in three dimensions, since the transport takes the path of lowest resistance. The image series for ET were recorded using High-Angle Annular Dark Field Scanning Transmission Electron Microscopy (HAADF-STEM). We have studied three different particulate silica hydrogels based on primary particles with sizes ranging from 3.6 nm to 22 nm and with pore-size averages from 18 nm to 310 nm. Here, we highlight the nanostructure of the particle network and the interpenetrating pore network in two and three dimensions. The interconnectivity and distribution of width of the porous channels were obtained from the three-dimensional tomography studies while they cannot unambiguously be obtained from the two-dimensional data. Using ET, we compared the interconnectivity and accessible pore volume fraction as a function of pore size, based on direct images on the nanoscale of three different hydrogels. From this comparison, it was clear that the finest of the gels differentiated from the other two. Despite the almost identical flow properties of the two finer gels, they showed large differences concerning the accessible pore volume fraction for probes corresponding to their (two-dimensional) mean pore size. Using 2D pore size data, the finest gel provided an accessible pore volume fraction of over 90%, but for the other two gels the equivalent was only 10–20%. However, all the gels provided an accessible pore volume fraction of 30–40% when taking the third dimension into account.
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| 6. |
- Hamngren Blomqvist, Charlotte, 1984, et al.
(author)
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Pore size effects on convective flow and diffusion through nanoporous silica gels
- 2015
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In: Colloids and Surfaces A: Physicochemical and Engineering Aspects. - : Elsevier BV. - 0927-7757 .- 1873-4359. ; 484, s. 288-296
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Journal article (peer-reviewed)abstract
- Material structure has great impact on mass transport properties, a relationship that needs to be understood on several length scales. Describing and controlling the properties of flow through soft materials are both challenges concerning the industrial use of gel structures. This paper reports on how the porous structure in nanoporous materials affects the water transport through them. We used three different silica gels with large differences in the pore sizes but of equal silica concentration. Particle morphology and gel structure were studied using high-resolution transmission electron microscopy and image analysis to estimate the pore size distribution and intrinsic surface area of each gel. The mass transport was studied using a flow measurement setup and nuclear magnetic resonance diffusometry. The average pore size ranged from approximately 500. nm down to approximately 40. nm. An acknowledged limit for convective flow to occur is in the pore size range between 100 and 200. nm. The results verified the existence of a non-linear relationship between pore size and liquid flow at length scales below 500. nm, experimentally. A factor of 4.3 in flow speed separated the coarser gel from the other two, which presented almost identical flow speed data despite a factor 3 in pore size difference. In the setup, the mass transport in the gel with the largest pores was flow dominated, while the mass transport in the finer gels was diffusion dominated. Besides providing new insights into mass transport as a function of pore sizes, we conclude that three-dimensional analysis of the structures is needed for a comprehensive understanding of the correlation between structure and mass transport properties.
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| 7. |
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| 8. |
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| 9. |
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| 10. |
- Klarbring, Anders, 1957-, et al.
(author)
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Residual Stress Fields in Soft Tissues
- 2004
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In: 21st International Congress of Theoretical and Applied Mechanics,2004. ; , s. 20-20
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Conference paper (peer-reviewed)
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| 11. |
- Mellgren, Jonas, 1997, et al.
(author)
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Improved Facial and Skull-base Symmetry Following Osteotomy and Distraction of Unilateral Coronal Synostosis.
- 2024
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In: Plastic and reconstructive surgery. - 1529-4242. ; 153:2, s. 447-456
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Journal article (peer-reviewed)abstract
- Unilateral coronal synostosis (UCS) results in a surgically demanding deformation, as the deformity is asymmetric in the calvarium but also presents with facial scoliosis and orbital dystopia. Traditional cranioplasties correct the forehead but have little effect on the face and orbits. Here, we describe a consecutive series of patients operated for UCS with osteotomy of the fused suture combined with distraction osteogenesis (FOD).Fourteen patients [mean age: 8.0 months (range: 4.3-16.6 months)] were included in this study. We measured and compared the orbital dystopia angle (ODA), anterior cranial fossa deviation (ACFD), and anterior cranial fossa cant (ACFC) between results from preoperative computed tomography and those at distractor removal.Blood loss was 6.1 mL/kg (range: 2.0-15.2 mL/kg), and length of stay was 4.4 days (range: 3.0-6.0 days). We observed significant improvements in the ODA from [median (95% confidence interval)] -9.8° (-12.6° to -7.0°) to -1.1° (-3.7° to -1.5°) (p<0.001), ACFD from 12.9° (9.2-16.6°) to 4.7° (1.5-7.9°) (p<0.001), and ACFC from 2.5° (1.5-3.5°) to 1.7° (0.0-3.4) (p=0.003).The results showed that osteotomy combined with a distractor for UCS straightened the face and relieved orbital dystopia by affecting the nose angle relative to the orbits, correcting the deviation of the cranial base in the anterior fossa, and lowering the orbit on the affected side. Furthermore, this technique demonstrated a favorable morbidity profile with low perioperative bleeding and a short inpatient period, suggesting its potential to improve the surgical treatment of UCS.
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| 12. |
- Michaëlsson, Isak, et al.
(author)
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Circulating Brain-Injury Markers After Surgery for Craniosynostosis
- 2023
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In: World Neurosurgery. - : Elsevier BV. - 1878-8750 .- 1878-8769. ; 173
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Journal article (peer-reviewed)abstract
- Objective: Historically, there have been few quantitative methods for effectively evaluating outcomes after surgery for craniosynostosis. In this prospective study, we assessed a novel approach for detecting possible postsurgery brain injury in patients with craniosynostosis. Methods: We included consecutive patients operated on for sagittal (pi-plasty or craniotomy combined with springs) or metopic (frontal remodeling) synostosis at the Craniofacial Unit at Sahlgrenska University Hospital, Gothenburg, Sweden, from January 2019 to September 2020. Plasma concentrations of the brain-injury biomarkers neurofilament light (NfL), glial fibrillary acidic protein (GFAP), and tau were measured immediately before induction of anesthesia, immediately before and after surgery, and on the first and the third postoperative days using single-molecule array assays. Results: Of the 74 patients included, 44 underwent craniotomy combined with springs for sagittal synostosis, 10 underwent pi-plasty for sagittal synostosis, and 20 underwent frontal remodeling for metopic synostosis. Compared with baseline, GFAP level showed a maximal significant increase at day 1 after frontal remodeling for metopic synostosis and pi-plasty (P = 0.0004 and P = 0.003, respectively). By contrast, craniotomy combined with springs for sagittal synostosis showed no increase in GFAP. For neurofilament light, we found a maximal significant increase at day 3 after surgery for all procedures, with significantly higher levels observed after frontal remodeling and pi-plasty compared with craniotomy combined with springs (P < 0.001). Conclusions: These represent the first results showing significantly increased plasma levels of brain-injury biomarkers after surgery for craniosynostosis. Furthermore, we found that more extensive cranial vault procedures resulted in higher levels of these biomarkers relative to less extensive procedures.
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| 13. |
- Olsson, Mats, 1960, et al.
(author)
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Carotenoid intake does not mediate a relationship between reactive oxygen species and bright colouration: experimental test in a lizard.
- 2008
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In: The Journal of experimental biology. - : The Company of Biologists. - 0022-0949 .- 1477-9145. ; 211:Pt 8, s. 1257-61
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Journal article (peer-reviewed)abstract
- We performed experiments on male Australian painted dragon lizards (Ctenophorus pictus) to test the hypothesis that carotenoids can scavenge reactive oxygen species (ROS), protecting the organism from oxidative stress, and that this capacity is reflected in skin colours involved in signalling. Subsequent to 4 weeks of carotenoid treatment we used flow cytometry to analyse unspecified ROS (H(2)O(2), singlet oxygen, superoxide and peroxynitrite level), hereafter termed ROS, and baseline superoxide specifically (bSO in peripheral blood cells). Mean background levels of ROS and bSO did not differ between carotenoid-treated and control males. bSO, which represents the superoxide level in un-manipulated blood, was negatively correlated with colour development in all males, regardless of carotenoid treatment. Thus, carotenoid intake does not reduce circulating levels of ROS or bSO, suggesting that carotenoids are inefficient antioxidants in vivo and, therefore, are unlikely to provide a direct link between oxidative stress and colouration.
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| 14. |
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| 15. |
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| 16. |
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| 17. |
- Olsson, Mats, 1960, et al.
(author)
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Free radicals run in lizard families.
- 2008
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In: Biology letters. - : The Royal Society. - 1744-9561 .- 1744-957X. ; 4:2, s. 186-8
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Journal article (peer-reviewed)abstract
- In the ageing individual, the production of reactive oxygen species (ROS) accelerates with cell senescence. Depending on the heritability of the underlying processes that determine net ROS levels, this may influence ageing per se and its evolutionary direction and rate of change. In order to understand the inheritance and evolution of net ROS levels in free-ranging lizards, we used flow cytometry together with ROS-sensitive fluorogenic probes to measure ROS in lizard blood cells. We measured basal levels of (i) non-specific ROS (superoxide, singlet oxygen, H2O2 and peroxynitrite), (ii) superoxide specifically and (iii) superoxide after CCCP treatment, which elevated ROS production in the mitochondria. The cumulative level of non-specific ROS was higher in adults than juveniles and superoxide level showed high heritability and variability among families. We suggest that the evolution of ROS dynamics may be ROS species specific and perhaps depend on the relative degree of uni- or biparental inheritance of ROS main regulatory pathways.
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| 18. |
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| 19. |
- Olsson, Mats, 1960, et al.
(author)
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Haldane rules: costs of outbreeding at production of daughters in sand lizards
- 2004
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In: Ecology Letters. - : Wiley. - 1461-023X .- 1461-0248. ; 7:10, s. 924-928
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Journal article (peer-reviewed)abstract
- Haldane's rule is one of the most widely applicable paradigms in evolutionary biology, stating that in species crossings, the heterogametic sex will suffer more severely in terms of sterility and inviability. We address this in a within-species outbreeding situation by assessing the risk of producing inviable offspring depending on the sex ratio of the clutch produced in between-population crossings in the laboratory. In crossings between male and female sand lizards (Lacerta agilis) from two different sampling regions, one in Sweden, one in central Europe, risk of gametic incompatibility is unaffected by outbreeding, but offspring from between-population crossings show 300% higher malformation frequency and 10% lower hatching success. The risk of having inviable offspring increases with the production of daughters, i.e. the hemizygous sex in this species (ZW). Such sex-specific genetic costs of offspring production need to be incorporated into life history ecology, e.g. sex allocation theory.
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| 20. |
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| 21. |
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| 22. |
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| 23. |
- Olsson, Mats, 1960, et al.
(author)
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Sex differences in sand lizard telomere inheritance: paternal epigenetic effects increases telomere heritability and offspring survival
- 2011
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In: PLoS One. - : Public Library of Science (PLoS). - 1932-6203. ; 6:4
-
Journal article (peer-reviewed)abstract
- Background: To date, the only estimate of the heritability of telomere length in wild populations comes from humans. Thus, there is a need for analysis of natural populations with respect to how telomeres evolve. Methodology/Principal findings: Here, we show that telomere length is heritable in free-ranging sand lizards, Lacerta agilis. More importantly, heritability estimates analysed within, and contrasted between, the sexes are markedly different; son-sire heritability is much higher relative to daughter-dam heritability. We assess the effect of paternal age on Telomere Length (TL) and show that in this species, paternal age at conception is the best predictor of TL in sons. Neither paternal age per se at blood sampling for telomere screening, nor corresponding age in sons impact TL in sons. Processes maintaining telomere length are also associated with negative fitness effects, most notably by increasing the risk of cancer and show variation across different categories of individuals (e.g., males vs females). We therefore tested whether TL influences offspring survival in their first year of life. Indeed such effects were present and independent of sex-biased offspring mortality and offspring malformations. Conclusions/Significance: TL show differences in sex-specific heritability with implications for differences between the sexes with respect to ongoing telomere selection. Paternal age influences the length of telomeres in sons and longer telomeres enhance offspring survival.
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| 24. |
- Olsson, Mats, 1960, et al.
(author)
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Sexual differences in telomere selection in the wild
- 2011
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In: Molecular Ecology. ; 20, s. 2085-2099
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Journal article (peer-reviewed)abstract
- Telomere length is restored primarily through the action of the reverse transcriptase telomerase, which may contribute to a prolonged lifespan in some but not all species and may result in longer telomeres in one sex than the other. To what extent this is an effect of proximate mechanisms (e.g., higher stress in males, higher estradiol/estrogen levels in females), or is an evolved adaptation (stronger selection for telomere length in one sex), usually remains unknown. Sand lizard (Lacerta agilis) females have longer telomeres than males and better maintain telomere length through life than males do. We also show that telomere length more strongly contributes to life span and lifetime reproductive success in females than males and that telomere length is under sexually diversifying selection in the wild. Finally, we performed a selection analysis with number of recruited offspring into the adult population as a response variable with telomere length, life span and body size as predictor variables. This showed significant differences in selection pressures between the sexes with strong ongoing selection in females, with these three predictors explaining 63% of the variation in recruitment. Thus, the sexually dimorphic telomere dynamics with longer telomeres in females is a result of past and ongoing selection in sand lizards. Finally, we compared the results from our selection analyses based on Telometric-derived data to the results based on data generated by the software ImageJ. ImageJ resulted in shorter average telomere length, but this difference had virtually no qualitative effect on the patterns of ongoing selection.
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| 25. |
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| 26. |
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| 27. |
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| 28. |
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| 29. |
- Olsson, Tobias, 1977-, et al.
(author)
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Boundary Value Problems of an Initially Stressed Body
- 2004
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Reports (other academic/artistic)abstract
- The initial strain in a body can be described by a two-point tensor that maps tangent vectors between a local stress free configuration (manifolds) and the initially strained configuration. The initial strain tensor can be used to form a metric tensor and this metric can be used to induce a third manifold. The boundary value problem of an elastic body is in this paper formulated on these three manifolds: the induced manifold, the initially strained configuration and the local stress free configuration. Moreover, we consider a hyperelastic body with incompressible properties and we show that in that case, the divergence of the first Piola- Kirchhoff stress tensor defined on the initially strained configuration and on the induced manifold coincide. There-fore, we conclude that for an incompressible material, the boundary value problems stated on the initially strained configuration and on the induced manifold are the same.
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| 30. |
- Olsson, Tobias, 1977-
(author)
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Modeling Residual Stress Fields in Soft Tissues : with Application to Human Arteries
- 2004
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Licentiate thesis (other academic/artistic)abstract
- Biomechanics or Mechanics of Biology comprises many different fields. This thesis deals with soft tissues or living tissues and the fact that these materials live in a pressurized environment. This means that an unloaded tissue may not be stress free. The stress in an unloaded body is usually called residual stress. This thesis consist of an introduction to continuum mechanics and to soft tissues, and three research papers.The first paper deals with a zero stress configuration and the question of compatibility. It is shown that the zero stress configuration not necessarily constitutes a compatible body. The condition for compatibility is analyzed and exemplified on a cylinder and a sphere.In the second paper a model for residually stressed arteries based on local deformations is developed. The material properties for a human aorta is identified by the solution to an optimization problem. The resulting initial strains show a non constant behavior and this behavior cannot be described by the commonly used opening- angle model.The last paper is about formulating boundary value problems for initially stressed bodies in three different reference configurations. Firstly, the equilibrium equation and constitutive relation are stated on the unloaded residually stressed body. Secondly, all material points are relieved from stress by a tangent map and the new stress free configuration, which may be incompatible, is used to state the boundary value problem. Thirdly; we use the relieving tangent map to induce a new metric on the body. This induced metric is in general non Euclidean. Finally, we formulate the boundary value problem on this manifold.
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| 31. |
- Olsson, Tobias, 1977-
(author)
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Soft Tissue Mechanics with Emphasis on Residual Stress Modeling
- 2007
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Doctoral thesis (other academic/artistic)abstract
- This thesis concerns residual stress modeling in soft living tissues. The word living means that the tissue interacts with surrounding organs and that it can change its internal properties to optimize its function. From the first day all tissues are under pressure, due, for example, to gravity, other surrounding organs that utilize pressure on the specific tissue, and the pressure from the blood that circulates within the body. This means that all organs grow and change properties under load, and an unloaded configuration is never present within the body. When a tissue is removed from the body, the obtained unloaded state is not naturally stress free. This stress within an unloaded body is called residual stress. It is believed that the residual stress helps the tissue to optimize its function by homogenizing the transmural stress distribution.The thesis is composed of two parts: in the first part an introduction to soft tissues and basic modeling is given and the second part consist of a collection of five manuscripts. The first four papers show how residual stress can be modeled. We also derive evolution equation for growth and remodeling and show how residual stress develops under constant pressure. The fifth paper deals with damage and viscosity in soft tissues.
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| 32. |
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| 33. |
- Sagvik, Jörgen, 1972, et al.
(author)
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A genetic component of resistance to fungal infection in frog embryos.
- 2008
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In: Proceedings. Biological sciences / The Royal Society. - : The Royal Society. - 0962-8452. ; 275:1641, s. 1393-6
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Journal article (peer-reviewed)abstract
- The embryo has traditionally been considered to completely rely upon parental strategies to prevent threats to survival posed by predators and pathogens, such as fungi. However, recent evidence suggests that embryos may have hitherto neglected abilities to counter pathogens. Using artificial fertilization, we show that among-family variation in the number of Saprolegnia-infected eggs and embryos in the moor frog, Rana arvalis, cannot be explained by maternal effects. However, analysed as a within-females effect, sire identity had an effect on the degree of infection. Furthermore, relatively more eggs and embryos were infected when eggs were fertilized by sperm from the same, compared with a different, population. These effects were independent of variation in fertilization success. Thus, there is likely to be a significant genetic component in embryonic resistance to fungal infection in frog embryos. Early developmental stages may show more diverse defences against pathogens than has previously been acknowledged.
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| 34. |
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| 35. |
- Sagvik, Jörgen, 1972, et al.
(author)
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Intraspecific variation in resistance of frog eggs to fungal infection
- 2007
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In: Evolutionary Ecology. - : Springer Science and Business Media LLC. - 1573-8477 .- 0269-7653. ; Online
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Journal article (peer-reviewed)abstract
- Documenting sources of variation in host viability at pathogen exposure within and among populations is an important task in order to predict host-pathogen evolutionary dynamics. In the present study, we investigated family and population variation in the degree of embryonic infection of the pathogenic fungus Saprolegnia spp., by infecting moor frog (Rana arvalis) eggs from six populations and exposing them to two different temperatures. We found a significant family effect on the degree of Saprolegnia-infection of eggs and embryos, suggesting that there is genetic variation in resistance among embryos, or variation among females in some aspect of maternally induced resistance. Furthermore, infection level differed significantly between temperatures, with most families having more infected eggs in the relatively colder temperature. However, eggs and embryos from the different populations showed different degrees of Saprolegnia-infection in the two temperatures, i.e., there was a significant population × temperature interaction on the proportion of infected eggs. Thus, the degree of Saprolegnia-infection is sensitive to variation at the level of the family, population and environmental conditions, suggesting that responses to fungal outbreaks will vary geographically and will be difficult to predict.
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| 36. |
- Sagvik, Jörgen, 1972, et al.
(author)
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Outbreeding depression in the common frog, Rana temporaria
- 2005
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In: Conservation Genetics. - : Springer Science and Business Media LLC. - 1566-0621 .- 1572-9737. ; 6:2, s. 205-211
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Journal article (peer-reviewed)abstract
- Theory suggests that parental relatedness is a continuous variable with a fitness optimum that we heretoforth will refer to as 'optimal outbreeding. In the present paper, we test this proposition from a conservation (translocation) perspective. Amphibians are facing a global decline and many amphibian populations are today small and threatened by extinction. Because genetic differentiation is often high between amphibian populations, they could be particularly sensitive to outbreeding depression, e.g. due to breakdown of locally adapted gene complexes. We tested if outbreeding would reduce fitness in common frogs, Rana temporaria, crossed from a large and an isolated, small population, separated by 130 km, using artificial fertilization. For females from the large population, tadpoles were significantly smaller and more malformed in crosses with males from the small population, than with males from the large population. For the small population, however, no significant paternal genetic effects could be found. The difference in response to outbreeding between populations was accompanied with significant differences in the importance of maternal effects. We conclude that care should be taken when translocating frogs between distantly related populations to avoid outbreeding depression.
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| 37. |
- Schwartz, TS, et al.
(author)
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Complex selection associated with Hox genes in a natural population of lizards
- 2011
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In: Journal of Evolutionary Biology. - 1010-061X. ; 24:11, s. 2520-2524
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Journal article (peer-reviewed)abstract
- Hox genes are recognized for their explanatory power of bilateral development. However, relatively little is known about natural variation in, and the evolutionary dynamics of, Hox genes within wild populations. Utilizing a natural population of sand lizards (Lacerta agilis), we screened HoxA13 for genetic variation and an association with incidence of offspring malformations. We found significant effects of parental genetic similarity and offspring sex, and their interaction, on risk of hatching malformed as an offspring. We also found within population genetic variation in HoxA13, and identified a significant effect of a three-way interaction among Hox genotype, parental genetic similarity, and offspring sex on the risk of hatching malformation. Since malformed offspring in this population do not survive to maturity, this study reveals complex and ongoing selection associated with Hox genes in a wild reptile population. Importantly, this demonstrates the utility of natural populations in unveiling microevolutionary processes shaping variation in highly conserved genes.
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| 38. |
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| 39. |
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| 40. |
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| 41. |
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| 42. |
- Söfteland, Madiha Bhatti, 1977, et al.
(author)
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Correction of Unicoronal Synostosis With Springs: Two Patients With Improved Facial Symmetry
- 2024
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In: JOURNAL OF CRANIOFACIAL SURGERY. - 1049-2275 .- 1536-3732. ; 35:1, s. 10-12
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Journal article (peer-reviewed)abstract
- Objective: Surgical correction of unicoronal synostosis (UCS) entails extensive cranioplasties which do not address facial scoliosis. This paper presents the first results with springs that motivated the shift from extensive cranioplasties to dynamic techniques for surgical correction of UCS.Methods: Two cases of UCS were operated with a linear osteotomy combined with springs. The deviation in facial symmetry (orbital dystopia angle) and skull base angles were measured on pre and postoperative computed tomography scans until 3 years of age.Results: The facial scoliosis was corrected. At spring removal, the orbital dystopia angle had gone from a 9.2 to 13.2-degree deviation preoperatively to a 0.5 to 0.9-degree overcorrection compared with the ideal 0-degree deviation. Also, the skull base deviation improved.Conclusion: Linear osteotomy combined with springs corrects the facial scoliosis in UCS. These cases indicate that dynamic methods may be beneficial for improving the results of surgical correction of UCS.
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| 43. |
- Townsend, Philip, 1991, et al.
(author)
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Tessellation-based stochastic modelling of 3D coating structures imaged with FIB-SEM tomography
- 2021
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In: Computational Materials Science. - : Elsevier BV. - 0927-0256 .- 1879-0801. ; 197
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Journal article (peer-reviewed)abstract
- To facilitate printing, coatings are typically applied to paperboard used for packaging to provide a good surface for application. To optimise the performance of the coating, it is important to understand the relationship between the microstructure of the material and its mass transport properties. In this work, three samples of paperboard coating are imaged using combined focused ion beam and scanning electron microscope (FIB-SEM) tomography data appropriately segmented to characterise the internal microstructure. These images are used to inform a parametric, tessellation-based stochastic three-dimensional model intended to mimic the irregular geometry of the particles that can be seen in the coating. Parameters for the model are estimated from the FIBSEM image data, and we demonstrate good agreement between the real and virtual structures both in terms of geometrical measures and mass transport properties. The development of this model facilitates exploration of the relationship between the structure and its properties.
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| 47. |
- Uller, Tobias, 1977, et al.
(author)
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Crosses between frog populations reveal genetic divergence in larval life history at short geographic distance
- 2006
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In: Biological Journal of the Linnean Society. - : Oxford University Press (OUP). - 0024-4066. ; 89:1, s. 189-195
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Journal article (peer-reviewed)abstract
- A number of studies have documented interpopulation divergence in amphibian larval life-history traits across latitudes. Because many frogs are philopatric and have a patchy habitat distribution, genetic divergence could also exist on a much smaller geographical scale, revealed by recent estimates of population divergence using molecular markers. Whether this divergence is reflected in phenotypic traits is virtually unknown. Using artificial fertilization, individuals of the common frog, Rana temporaria, were crossed from two populations situated 130 km apart and differing in population size. The pattern of size at metamorphosis showed evidence of non-additive effects, as demonstrated by a significant interaction between male and female population of origin. Outbreeding resulted in an increase in metamorph size when eggs from the small population were fertilized with sperm from the large population. In the reciprocal cross, however, the pattern was in the opposite direction, with no significant effect of male population of origin. Genetic divergence of populations separated by a relatively short geographical distance may be more common in frogs than previously acknowledged, with potential implications for conservation of declining amphibian species.
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| 48. |
- Uller, Tobias, 1977, et al.
(author)
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Direct exposure to corticosterone during embryonic development influences behaviour in an ovoviviparous lizard
- 2006
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In: ETHOLOGY. - : Wiley. - 0179-1613 .- 1439-0310. ; 112:4, s. 390-397
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Journal article (peer-reviewed)abstract
- It is becoming increasingly clear that conditions experienced during embryonic development can be of major importance for traits subsequent to parturition or hatching. For example, in mammals, offspring from stressed mothers show a variety of changes in behavioural, morphological, and life-history traits. The effects of maternal stress on trait development are believed to be mediated via transfer of glucocorticoids, the main hormones released during the stress response, from mother to offspring. However, also other physiological maternal responses during stress could be responsible for changes in offspring phenotype. We investigated the direct effects of corticosterone on offspring development, without other confounding factors related to increased maternal stress, by injection of corticosterone in eggs of the ovoviviparous lizard Lacerta vivipara. Corticosterone-manipulated offspring did not show impaired development, reduced body size or body condition at parturition. However, corticosterone-treated offspring showed altered anti-predator behaviour, as measured by the time required to emerge from shelter after a simulated predator attack. Differential steroid exposure during development, possibly mediated by maternal stress response, may explain some of the variation in behaviour among individuals in natural populations.
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| 49. |
- Uller, Tobias, 1977, et al.
(author)
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Ectoparasite susceptibility in lizards from populations sympatric and allopatric with ticks
- 2004
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In: Ecoscience. - 1195-6860. ; 11:4, s. 428-432
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Journal article (peer-reviewed)abstract
- Theory suggests that host-parasite interaction should lead to local adaptation of parasites to their hosts and vice versa. The degree of local adaptation depends on, for example, migration, relative generation time of host and parasite, and the number of host species. Furthermore, in any coevolutionary process, local adaptation of one species is dependent on the evolution of sympatric and allopatric populations of the other species, and the degree of gene flow. The tick Ixodes ricinus is a generalist tick feeding on hosts of a variety of taxa. We contrasted populations of common lizards (Lacerta vivipara) differing in their evolutionary history of exposure to ticks. Juvenile lizards were raised in a common garden experiment. We monitored growth rate, physiological performance, and aspects of immune function in tick-exposed and control offspring. There were no differences in response to tick infestation between host populations, with both sympatric and allopatric hosts showing impaired growth and endurance under parasite exposure. Ticks were marginally more engorged on allopatric hosts (P = 0.06); hence, our results do not support the hypothesis of local adaptation of parasites.
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